U.S. patent application number 15/932172 was filed with the patent office on 2021-05-20 for integrated system for the infixion and retrieval of implants.
The applicant listed for this patent is David S. Goldsmith. Invention is credited to David S. Goldsmith.
Application Number | 20210145445 15/932172 |
Document ID | / |
Family ID | 1000005564991 |
Filed Date | 2021-05-20 |
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United States Patent
Application |
20210145445 |
Kind Code |
A9 |
Goldsmith; David S. |
May 20, 2021 |
Integrated system for the infixion and retrieval of implants
Abstract
Described are coordinated apparatus and methods for drug
targeting, clearing the lumen, placing implants within the wall of,
and stenting, as necessary, any tubular anatomical structure with
single luminal entry. Miniature balls, or miniballs, are introduced
into the wall aeroballistically from within the lumen, or small
arcuate bands called stays inserted through the outer tunic by
means of a hand tool. When miniballs must be placed too closely
together to be controlled by hand, a positional control system
assists in discharge. Implantation within or proximal to diseased
tissue targeting, and thus concentrating the medication in that
tissue, miniballs and stays can be used to deliver and controllably
release multiple drugs, a radionuclide, or an open or closed loop
smart-pill, for example. A glossary of terms follows the
specification. Balance of abstract appended to the section entitled
Summary of the Invention.
Inventors: |
Goldsmith; David S.;
(Atlanta, GA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Goldsmith; David S. |
Atlanta |
GA |
US |
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Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20190247050 A1 |
August 15, 2019 |
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Family ID: |
1000005564991 |
Appl. No.: |
15/932172 |
Filed: |
February 14, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13694835 |
Jan 9, 2013 |
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15932172 |
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11986021 |
Nov 19, 2007 |
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13694835 |
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60860392 |
Nov 21, 2006 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2017/0065 20130101;
A61B 17/0057 20130101; A61B 17/3468 20130101; A61B 17/00491
20130101; A61B 18/18 20130101; A61B 2017/1205 20130101; A61B
2017/00411 20130101; A61F 2/82 20130101; A61B 17/12181 20130101;
A61B 17/12118 20130101; A61B 2017/00876 20130101 |
International
Class: |
A61B 17/12 20060101
A61B017/12; A61F 2/82 20060101 A61F002/82; A61B 17/34 20060101
A61B017/34; A61B 17/00 20060101 A61B017/00; A61B 18/18 20060101
A61B018/18 |
Claims
1. A jacket for encircling a tubular anatomical structure, said
structure itself a product of nature not claimed, wherein said
jacket comprises complementary open-ended semi cylindrical shells
fastened together along one long edge by spring-loaded hinges to
urge said semi cylindrical shells into a cylindrical conformation
when closed, said jacket lined with a shape-compliant material and
incorporating material magnetized perpendicularly to the long axis
of said tubular anatomical structure to draw magnetically
susceptible matter within said structure abaxially outward toward
said jacket.
2. A jacket according to claim 1 wherein said jacket derives its
magnetism by incorporation from the group of magnetic materials
comprising an intrinsically magnetic metal, an intrinsically
magnetic polymer, small permanent magnets fastened about the outer
surface of said jacket, and these in combinations to draw
magnetically susceptible matter from a ferrofluid coursing through
said lumen of said tubular anatomical structure and hold said
matter up against the lumen lining of said structure.
3. A jacket according to claim 1 wherein said jacket uses magnetism
obtained by selection from the group comprising an intrinsically
magnetic metal, and intrinsically magnetic polymer, and small
permanent magnets fastened about the outer surface of said jacket
to exercise a stenting function by drawing small magnetically
susceptible bodies infixed within the wall of said tubular
anatomical structure radially outward.
4. A jacket according to claims 1 and 2 wherein said jacket uses
said source of magnetism to draw magnetically susceptible matter
from a ferrofluid coursing through said lumen and hold said matter
up against the lumen lining of said structure.
5. A jacket according to claims 1 and 2 wherein said jacket uses
magnetism provided by electromagnets fastened about the outer
surface of said jacket to draw magnetically susceptible matter from
a ferrofluid coursing through said lumen and draw said matter into
the lumen wall of said structure.
6. A jacket according to claims 1, 2 , and 5 wherein said
electromagnets are adjusted in field strength in response to a
prescription program executed by a microprocessor.
7. A catheter with a muzzle at its distal end, enabling said
catheter when connected to an airgun, to aeroballistically
discharge small magnetically susceptible bodies according to claim
3 when spherical at an acute forward angle from within the lumen
into the wall surrounding the lumen of a tubular anatomical
structure such that said bodies are infixed within said wall in a
uniform pattern as is imperative to avoid nonuniformities in the
relative positioning of said small magnetically susceptible bodies,
so that a magnetic force applied abaxially toward said wall with an
extravascular tractive magnet draws said wall uniformly outward
over the area of said force as is essential to avoid a concentrated
focus of said force on few said bodies as would tear said wall.
8. A hand tool for infixing to a uniform depth small strip-shaped
bodies of magnetically susceptible matter according to claim 3
through the outer surface of the wall surrounding the lumen of said
tubular anatomical structure, enabling the operator to separately
position said strips quickly in a uniform pattern over the area of
an abaxially applied magnetic field as is imperative to avoid a
concentration of said force as would ohterwise tear said wall, said
tool delivering said strips from a stacked queue under static
spring force into a way for consecutive ejection as in a
stapler.
9. A catheter with small sockets arranged about its outer
circumference for receiving snap-in elevation and retraction
platforms, said platforms accepting insert tools so that said tools
can be raised into working position to allow the injection of said
spherical bodies according to claims 3 and 7 while fluid in a
uniform pattern as is essential to prevent a focused projection of
magnetic force on few magnetically susceptible spherical bodies as
would otherwise tear said wall and for preparing the internal
surface of said wall, itself a product of nature not claimed, in
preparation for the infixion of small magnetically susceptible
bodies, thereby allowing an encircling jacket exerting an
attractive force thereupon according to claims 1 and 2 to exercise
a stenting function by drawing said bodies radially outward,
wherein said tool inserts are selected from the group comprising
shavers, abraders, and injectors.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of parent
application Ser. No. 11/986,021, filed on 19 Nov. 2007 and
published on 11 Nov. 2010 as 20100286791 under the title Integrated
System for the Ballistic and Nonballistic Infixion and Retrieval of
Implants and also continuation-in-part application Ser. No.
13/694,835, filed on 9 Jan. 2013 and published on 12 Jun. 2014 as
2014/0163664 under the title Integrated System for the Ballistic
and Nonballistic Infixion and Retrieval of Implants with or without
Drug Targeting. Parent application Ser. No. 11/986,021 succeeded
and claimed the benefit of Disclosure Document 565662, filed on 21
Nov. 2004, and Provisional Patent Application 60/860,392, filed on
21 Nov. 2006 under 35 U.S.C. 119(e), the content of these earlier
disclosures incorporated by reference. This continuation-in-part
application supersedes parent application Ser. No. 11/986,021 and
continuation-in-part application Ser. No. 13/694,835, these earlier
applications herewith abandoned.
TABLE-US-00001 TABLE OF CONTENTS CROSS REFERENCE TO RELATED
APPLICATION TABLE OF CONTENTS BACKGROUND OF THE INVENTION 1. Field
of the invention 2. Preliminary description of the invention 3.
Terminology 4. Concept of the ductus-intramural implant 4a. Tissue
acceptance of ductus-intramural implant 4a(1). Significance of
sterile antixenic immune tissue reaction 4a(2). Duration, extent,
and outcome of sterile tissue reaction 4a(3). Tissue reaction
ameliorative measures 4b. Medicinal and medicated miniballs and
stays 4b(1). Drug-releasing and irradiating miniballs, stays, and
ferrofluids 4b(2). Local release of drugs by miniballs and stays
4b(3). Use of drug-releasing ductus-intramural implants to locally
counteract or reinforce angiogenic or other systemic medication
4b(4). System implant magnetic drug and radiation targeting 4b(5).
Circulating drug-blocking and drug interaction avoidance 4b(6).
Drug-targeting miniballs and stays 4c. Implants that radiate heat
on demand 4d. Chemical adjuvants and precautionary measures 4d(1).
Administration of target and target-adjacent
implantation-preparatory substances 4d(2). Ductus wall tumefacients
4d(3). Nontumefacient enabled attainment of implantable
ductus-intramural thickness 4e. Stabilization of the implant
insertion site 4e(1). Gross positional stabilization
(immobilizaton) of the implant insertion site 4e(2). Tissue
stabilization at the treatment site 4e(2)(a). Temperature
stabilization 4e(2)(b). Removal of vulnerable plaque or accreted
material at the implant insertion site 4f. Abrupt closure with
thrombus and vasospasm 4f(1). Risk of abrupt closure with thrombus
and vasospasm 4f(2). Prevention of abrupt closure with thrombus and
vasospasm 4g. Emergency recovery of miniballs and stays 5. Means
for the placement of ductus-intramural implants 6. Endoluminal
prehension of miniballs and ferrofluids 7. Comparison with prior
art angioplasty 8. Concept of the extraluminal stent 8a. Basic
strengths and weaknesses of prior art stenting in vascular,
tracheobronchial, gastrointestinal, and urological interventions
8b. The extraluminal stent 8b(1). The intraductal component of the
extraluminal stent and the means for its insertion 8b(1)(a). Types
of ductus-intramural implants used for stenting 8b(1)(b). Use of
ductus-intramural implants for stenting 8b(2). The extraductal
component of the extraluminal stent and the means for its insertion
8b(2)(a). Types of stent-jacket 8b(2)(a)(i). Extrinsically
magnetized stent-jackets 8b(2)(a)(ii). Intrinsically magnetized
stent-jackets 8b(2)(a)(iii). Hybrid extrinsically and intrinsically
magnetized stent-jackets 8b(2)(a)(iv). Quasi-intrinsically
magnetized stent-jackets 8b(2)(a)(v). Laminated stent-jackets
8b(2)(a)(vi). Spine and ribs-type stent-jackets 8b(2)(a)(vii).
Absorbable stent-jackets 8b(2)(a)(viii). Radiation shield-jackets
and radiation shielded stent-jackets absorbable and nonabsorbable
8c. Placement of the extraluminal stent 8c(1). Considerations as to
access 8c(2). Means for the placement of the stent-jacket 8d.
Closer comparison of extraluminal to endoluminal, or conventional,
stenting 8e. Accommodation of the adventitial vasculature,
innervation, and perivascular fat 8f. Necrosis and
atherogenesis-noninducing conformation of stent-jackets 8g. Means
for accommodating the vasa and nervi vasora with special reference
to the end-arterial form and neovascularization of the corronary
arteries 8h. Requirement for moisture barrier-coated viscoelastic
polyurethane foam linings 8i. Positional stabilization of implants
8i(1). Use of solid protein solders 8i(2). Means for inducing the
formation of a strong implant-tissue bond 9. Minimizing the risk of
rebound 10. Concept of ballistic insertion 11. Use of a positional
control system 12. Concept of the impasse-jacket 13. Concept of the
magnet-wrap 14. Concept of the nonjacketing side-entry connector
15. System requirements 16. System features
[0002] OBJECTS OF THE INVENTION
[0003] SUMMARY OF THE INVENTION
[0004] BRIEF DESCRIPTION OF THE DRAWINGS
[0005] DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0006] I. STENT-JACKETS AND STENT-JACKET SUPPORTING ELEMENTS
[0007] I1. General considerations to include insertion
[0008] I2. Structural and functional considerations
[0009] I3. Order of stent-jacket placement
[0010] I3a. Circumstances recommending the use of a shield-jacket
or preplacement of the stent-jacket
[0011] I3b. Sequence of stent-jacket placement and implantation
[0012] I3c. Sequence of stent-jacket placement and implantation in
relation to trap-extractor (recovery) electromagnet susceptibility
and field intensity
[0013] I4. Internal environment-resistant base-tube polymers,
metals, and combinations thereof
[0014] I5. Protective encapsulation of the stent-jacket
[0015] I6. Stent-jackets with sling string pull opener
[0016] I7. Stent and shield-jacket protective linings
[0017] I7a. Double-wedge stent- and shield-jacket rebound-directing
linings
[0018] I7a(1). Conformation of double-wedge linings
[0019] I7a(2). Functional background to double-wedge linings
[0020] I7a(3). Materials suitable for rebound-directing
double-wedge linings
[0021] I7a(4). Nonmagnetized base-tube and double-wedge
shield-jackets
[0022] I7b. Stent- and shield-jacket moisture barrier-coated
viscoelastic polyurethane foam linings
[0023] I7c. Stent- and shield-jacket anti-migration linings
[0024] I8. Radiation shielded stent-jackets
[0025] I9. Jacket end-ties and side-straps
[0026] I9a. Form of end-ties
[0027] I9b. Use of end-ties
[0028] I10. Absorbable extraluminal magnetic stent-jackets and
materials
[0029] I10a. Absorbable base-tube and stent-jacket, miniball, stay,
and clasp-magnet matrix materials
[0030] I10b. Noninvasive dissolution on demand of absorbable
stent-jackets, base-tubes, radiation shields, and miniballs
[0031] I10c. Absorbable and nonabsorbable periductal jackets with
medicated linings
[0032] I11. STENT-JACKET EXPANSION INSERTS
[0033] I11a. Expansion inserts absorbable, meltable, and
comminutable for time-discrete decremental contraction of
stent-jackets
[0034] I11b. Intracavitary infusion of fluid for lithotriptor
dissolution of long-term controlled destruction-time expansion
inserts or a final stone base-tube bonded layer in multilayered
expansion inserts
[0035] I11c. Absorbable stent-jacket expansion insert materials
with relatively short breakdown times
[0036] I11d. Lithotriptor-destructible stone stent-jacket expansion
inserts and differentially destructible expansion insert layers
[0037] I11e. Expansion insert bonding agents (adhesives)
[0038] I11e(1). Intrinsic shorter-term insert-to-base-tube and
segment-to-segment bonding agents
[0039] I11e(2). Longer-term expansion insert-to-base-tube and
layer-to-layer bonding agents
[0040] I11e(3). Extrinsic shorter-term (absorbable) to longer-term
(stone) layer bonding agents
[0041] I12. Retardation in the dissolution of absorbable
stent-jackets, stent-jacket expansion inserts, and stays
[0042] I13. Alternative procedure to the use of expansion
inserts
[0043] I14. SECTIONAL, OR CHAIN-STENTS, SEGMENTED AND
ARTICULATED
[0044] I14a. Purposes and types of chain-stent
[0045] I14b. Procedure for placement of a chain-stent
[0046] I15. MINIBALL AND FERROFLUID-IMPASSABLE JACKETS, OR
IMPASSE-JACKETS
[0047] I15a. Uses of impasse-jackets
[0048] I15b. Structure of impasse-jackets
[0049] I15c. Braced, compound, and chain impasse-jackets
[0050] I15d. Cooperative use of impasse-jackets in pairs and
gradient arrays
[0051] I15e. Direct lines from the body surface to and from
impasse- and other type jackets
[0052] I15f. Single and plural circuit pumping through direct lines
to jackets
[0053] I16. STENT-JACKET INSERTION TOOLS
[0054] I16a. Insertion tool structure
[0055] I16b. Use of the stent-jacket insertion tool
[0056] II. CLASP-MAGNETS
[0057] II1. Subcutaneous, suprapleural, and other organ-attachable
clasp- or patch-magnets
[0058] II2. Chemical isolation of patch-magnet and other implanted
components
[0059] III. MAGNET-WRAPS
[0060] III1. Use of a magnet-wrap
[0061] III2. Magnet-wrap structure
[0062] IV. CLASP-PATCHES AND CLASP-WRAPS
[0063] IV1. Creation of a magnetically retractable surface
layer
[0064] IV2. Use of a clasp-wrap
[0065] IV3. Clasp-wrap-alternative methods for achieving adhesion
to the outer surface of the ductus
[0066] IV3a. Stays configured and/or coated to promote tissue
infiltration and adhesion
[0067] IV3b. Injectable magnetic fluids
[0068] V. MINIBALLS
[0069] V1. Miniature ball implants
[0070] V2. Miniball types, radiation-emitting, medication,
drug-eluting magnetized, and magnetized
[0071] V3. Medication (nonstent) implants and medication-coated
miniballs, implants, and prongs
[0072] V4. Medication-coated miniballs, stays, and prongs with a
heat-activated (-melted, -denatured) tissue adhesive-hardener or
binder-fixative
[0073] V5. Heating control over implants and coated implants, to
include miniballs, stays, and prongs
[0074] V5a. Heating of implants and coated implants, to include
miniballs, stays, and prongs using implant-passive ductus-external
or extrinsic means
[0075] V5b. Extracorporeal energization of intrinsic means for
radiating heat from within medication implants and medication
and/or the tissue bonding-coatings of implants
[0076] V6. Chemical control over implants and coated implants, to
include miniballs, stays, and prongs
[0077] V7. Radiation-emitting (brachytherapeutic,
endocurietherapeutic, sealed source radiotherapeutic, internal
radiation therapy) miniballs
[0078] V8. Temporary (absorbable) ferromagnetic miniballs and other
implants
[0079] VI. ROTARY MAGAZINE CLIPS
[0080] VII. BARREL-ASSEMBLIES
[0081] VII1. Types and capabilities of barrel-assemblies
[0082] VII1a. Types of barrel-assemblies
[0083] VII1b. Capabilities of different type barrel-assemblies
[0084] VII2. Ablation and angioplasty-incapable
barrel-assemblies
[0085] VII2a. Simple pipe barrel-assemblies
[0086] VII2b. Simple pipe ablation and angioplasty-incapable
barrel-assembly muzzle-heads
[0087] VII2b(1). Simple pipe barrel-assembly with bounce-plate
[0088] VII2b(1)(a). Intracorporeally nondeployable nor adjustable
bounce-plate attachment
[0089] VII2b(1)(b). Intracorporeally controllable bounce-plates
[0090] VII2b(1)(b)(i). Intracorporeally controllable bounce-plate
with limited adjustability in elevation
[0091] VII2b(1)(b)(ii). Intracorporeally controllable bounce-plate
with precision adjustment in rebound elevation and rotation
[0092] VII2b(2). Trap and extraction recovery tractive
electromagnets for the recovery of loose and extraction of
mispositioned miniballs
[0093] VII2c. Application of simple pipe-type barrel-assembly to
the magnetic correction of tracheal and bronchial collapse
(veterinary)
[0094] VII2c(1). Treatment of tracheal collapse in the cervical
segments, i.e., cephalad or anterior to the thoracic inlet
[0095] VII2c(1)(a). Use of a magnet-wrap about the esophagus to
treat tracheal collapse in a small dog, for example
[0096] VII2c(1)(b). Use of a simple pipe barrel-assembly to treat
tracheal collapse in a small dog, for example
[0097] VII2c(2). Treatment of tracheal collapse in the thoracic
segments, i.e., caudad, or posterior, to the thoracic inlet
[0098] VII2d. Ablation and angioplasty-incapable radial discharge
barrel-assemblies
[0099] VII2d(1). Limited purpose single barrel (monobarrel) radial
discharge barrel-assembly
[0100] VII2d(2). Multiple radial discharge barrel-assemblies with
one- to four- or more-way radial discharge muzzle-heads
[0101] VII2d(3). Ablation and angioplasty-incapable radial
discharge barrel-assembly muzzle-heads
[0102] VII2d(3)(a). Monobarrel radial discharge barrel-assembly
muzzle-head
[0103] VII2d(3)(a)(i). Structure of monobarrel radial discharge
barrel-assemblies
[0104] VII2d(3)(a)(ii). Materials of radial discharge
barrel-assemblies
[0105] VII2d(3)(b). Muzzle-head turret-motor
(turret-servomotor)
[0106] VII2d(3)(c). Muzzle-head servomotor (turret-motor)
desiderata
[0107] VII2d(3)(d). Turret-motor operational modes
[0108] VII2d(3)(d)(i). Turret-motor rotational mode
[0109] VII2d(3)(d)(ii). Turret-motor oscillatory mode
[0110] VII2d(3)(d)(iii). Turret-motor heating mode
[0111] VII2d(3)(e). Radial discharge barrel-assembly working
arc
[0112] VII2d(3)(f). Rotation of working arc
[0113] VII2d(3)(g). Control of muzzle-head turret-motor angle
within working arc
[0114] VII2d(3)(h). Factors that affect muzzle-head nosing length
or reach, steerability, and trackability
[0115] VII2d(3)(i). Trap and extraction recovery tractive
electromagnets in radial discharge barrel-assemblies for the
recovery of loose and extraction of mispositioned miniballs
[0116] VII2d(3)(j). Blood-grooves on muzzle-heads for use in blood
vessels
[0117] VII2d(4). Forward drive and sag leveling and stabilizing
device
[0118] VII2d(4)(a). Use of a forward drive stabilizer
[0119] VII2d(4)(b). Structure of forward drive stabilizing and
leveling extension linkage
[0120] VII2d(5). Direction of radial discharge barrel-assembly
muzzle-head on discharge as antegrade (advancing, forward, distad)
or retrograde (withdrawing, backward, proximad)
[0121] VII2e. Simple pipe and radial discharge barrel-assembly
common elements
[0122] VII2e(1). Barrel-catheters, barrel-tubes, and
barrel-assemblies
[0123] VII2e(2). Connectors (couplings) for quick release and
reconnection of the barrel-assembly to the airgun with proper
alignment
[0124] VII2e(3). Twist-to-stop and lock connector (twist lock
connector, keyed spring lock connector)
[0125] VII2e(4). Engagement of the barrel-assembly in the
airgun
[0126] VII2e(5). Barrel-assembly end-plate
[0127] VII2e(6). Electrical connection of the barrel-assembly to
the airgun
[0128] VII2f. Radial discharge barrel-assembly elements
[0129] VII2f(1). Tube polymer nonintrinsic barrel-catheter
flexibility (bendability, trackability) setting and altering
elements
[0130] VII2f(1)(a). Tubing materials for barrel-catheters and
radial discharge barrel-tubes
[0131] VII2f(1)(b). Centering devices (centering disks)
[0132] VII2f(2). Embolic trap filter in radial discharge
muzzle-heads for use in the vascular tree
[0133] VII2f(2)(a). Trap filter deployment and retrieval
mechanism
[0134] VII2f(2)(b). Automatic disabling of implant-discharge,
radial projection units, and turret-motor
[0135] VII2f(3). Blood-tunnels
[0136] VII2f(4). Incorporation of a bounce-plate into radial
discharge barrel-assemblies
[0137] VII2f(5). Use of minimally and fully angioplasty-capable
radial discharge barrel-assemblies
[0138] VII2f(6). Ablation and angioplasty-incapable barrel-assembly
controls on the airgun
[0139] VII2g. Minimally ablation or ablation and
angioplasty-capable barrel-assemblies
[0140] VII2g(1). Minimally thermal ablation or angioplasty-capable
barrel-assemblies
[0141] VII2g(2). Minimally ablation or ablation and
angioplasty-capable barrel-assembly side-socket
[0142] VII2g(3). Minimally and fully (airgun-independent) ablation
or ablation and angioplasty-capable radial discharge
muzzle-heads
[0143] VII2g(3)(a). Rapid cooling catheter and cooling capillary
catheter for cooling heated turret-motor, electrically operated
radial projection unit lifting thermal expansion wires and heaters,
and recovery magnets
[0144] VII2g(3)(b). Turret-motor and recovery electromagnet
insulation, leads, and control of winding temperatures when used as
a heating elements in ablation or ablation and angioplasty-capable
barrel-assemblies
[0145] VII2g(3)(c). Thermal conduction windows (heat-windows) and
insulation of the muzzle-head body in minimally or fully thermal
ablation and thermal ablation and angioplasty-capable
(independently usable) barrel-assemblies
[0146] VII2g(3)(d). RADIAL PROJECTION UNITS
[0147] VII2g(3)(d)(i). Structure of radial projection units
[0148] VII2g(3)(d)(i)(1). Structure of electrically operated radial
projection units
[0149] VII2g(3)(d)(i)(2). Structure of fluidically and
microfluidically operated radial projection units
[0150] VII2g(3)(d)(i)(3). Extended projection scissors
lift-platform mechanism
[0151] VII2g(3)(e). RADIAL PROJECTION UNIT TOOL-INSERTS
[0152] VII2g(3)(e)(i). Types and functions of radial projection
unit tool-inserts, electrical and fluidic or Piped
[0153] VII2g(3)(e)(ii). Self-contained electrical/fluid
system-neutral tool-inserts, to include injection and ejection
syringes
[0154] VII2g(3)(e)(iii). Self-contained electrical/fluid
system-neutral tool-insert internal stopping membranes and lifting
springs
[0155] VII2g(3)(e)(iv). Electrical and electrochemical
tool-inserts, to include gas discharged injection and ejection
syringes
[0156] VII2g(3)(e)(v). Temperature control in electrical
tool-inserts
[0157] VII2g(3)(e)(vi). Fluid-operated tool-inserts, to include
ejector-irrigator-aspirators and injectors
[0158] VII2g(3)(e)(vii). Use of flow-reversible tool-inserts for
microaspiration
[0159] VII2g(3)(e)(viii). Temperature control in fluid (piped)
tool-inserts
[0160] VII2g(3)(e)(ix). Doublet irrigator-aspirator tool-inserts,
or point-washers
[0161] VII2g(3)(e)(x). Elimination of gases from fluid radial
projection unit lines
[0162] VII2g(3)(f). Radial projection unit control and control
panels, elecrical and fluidic or piped
[0163] VII2g(3)(g). Coordinated use of aspiration and piped radial
projection units to remove diseased tissue or obtain tissue samples
for analysis
[0164] VII2g(4). Minimally ablation and ablation and
angioplasty-capable barrel-assembly control panels
[0165] VII2h. ABLATION AND ABLATION AND ANGIOPLASTY-CAPABLE
BARREL-ASSEMBLIES
[0166] VII2h(1). Distinction in ablation or ablation and
angioplasty-capable barrel-assemblies as unitary or bipartite
[0167] VII2h(2). Specific advantages in the elimination or
minimization of connection to the airgun (tethering)
[0168] VII2h(3). The radial discharge barrel-assembly as a separate
and independent angioplasty device
[0169] VII2h(4). Componentry required for airgun-independent
use
[0170] VII2h(5). Thermal ablation and angioplasty-(lumen wall
priming searing- or cautery-) capable barrel-assemblies
[0171] VII2h(6). Ablation and ablation and angioplasty-capable
barrel-assembly end-sockets
[0172] VII2h(7). Ablation and ablation and angioplasty-capable
barrel-assembly side-socket s
[0173] VII2h(8). BARREL-ASSEMBLY POWER AND CONTROL HOUSING
[0174] VII2h(8)(a). Connection of the power and control housing to
the airgun
[0175] VII2h(8)(b). Slidable ablation or ablation and
angioplasty-capable barrel-assembly power and control housing
[0176] VII2h(8)(c). Universal barrel-assembly power and control
housing
[0177] VII2h(8)(d). Rechargeable battery pack local to the
electrical terminals
[0178] VII2h(9)(e). Ablation and ablation and angioplasty-capable
onboard barrel-assembly control
[0179] VII2h(9)(f). Ablation and ablation and angioplasty-capable
barrel-assembly onboard control Panel
[0180] VII2h(10). Control of transluminal rate of translation
[0181] VII2i. Procedure for the extraluminal stenting of a smaller
vas using the apparatus described herein
[0182] VII2j. THROUGH-BORE, OR COMBINATION-FORM,
BARREL-ASSEMBLIES
[0183] VII2j(1). Incorporation of adscititious capabilities into
barrel-assemblies
[0184] VII2j(2). Accommodation of rotational ablating and
atherectomizing side-cutting devices in combination-forms
[0185] VII2j(3). Types of combination-form barrel-assemblies
[0186] VII2j(4). Forward-directed clearing (ablation and
angioplasty) means for integration into the muzzle-Head
[0187] VII2j(5). Barrel-assembly with built in excimer laser
[0188] VII2j(6). Barrel-assembly with exchangeable or built in
rotational atherectomy burr
[0189] VII2j(7). Flow-through barrel-assembly for use in blood
vessels
[0190] VII2j(8). Widely applicable barrel-assembly
[0191] VIII. RADIAL PROJECTION CATHETERS
[0192] VIII1. Types of radial projection catheters
[0193] VIII2. Simple, or noncombination-form, radial projection
catheters
[0194] VIII3. THROUGH-BORE, OR COMBINATION-FORM, RADIAL PROJECTION
CATHETERS
[0195] VI114. Slidable projection catheter power and control
housing
[0196] VI115. Fabrication of radial projection catheters
[0197] IX. SIDE-PORTS
[0198] IX1. Proximal side-ports in angioplasty-capable
barrel-assemblies
[0199] IX2. Proximal side-ports in combination-form
barrel-assemblies and combination-form radial projection
catheters
[0200] IX3. Distal side-ports in combination-form barrel-assemblies
and combination-form radial projection catheters
[0201] X. Steering and emergency recovery of implants with the aid
of an external (extracorporeal) Electromagnet
[0202] X1. Use of an external electromagnet to assist in steering
or in freeing the muzzle-head
[0203] X2. Use of an external electromagnet to assist in mishap
recovery
[0204] X2a. Interception and recovery of a miniball entering the
circulation
[0205] X2a(1). Midprocedural interception and recovery of a
miniball entering the circulation
[0206] X2a(2). Postprocedural recovery of a miniball in the
vascular tree
[0207] X2b. Stereotactic resituation of a mispositioned
miniball
[0208] X2c. Stereotactic arrest and extraction of a circulating,
dangerously mispositioned, or embolizing miniball
[0209] X2d. Downstream disintegration of a circulating miniball
[0210] X3. Perforations along the gastrointestinal tract
[0211] XI. HYPDXIA AND ISCHEMIA-AVERTING ELEMENTS
[0212] XI1. Blood-grooves
[0213] XI2. Blood-tunnels
[0214] XI3. Flow-through bore in combination-form barrel-assemblies
and combination-form radial projection catheters used in blood
vessels
[0215] XI4. Push-arm radial projection unit tool-inserts
[0216] XII. SERVICE-CATHETERS
[0217] XII1. Service-catheters, service-channels, and use of the
barrel-assembly as a guide-catheter
[0218] XII2. Muzzle-head access through a service-channel without
the aid of and by means of inserting a service-catheter
[0219] XII3. Cyanoacrylate cement injection service-catheter
[0220] XII4. Service-channel adhesive delivery line
[0221] XII5. Cooling catheters (temperature-changing
service-catheters)
[0222] XII6. Preparation of service-catheters for use as
transbarrel-assembly hypotubes
[0223] XII7. Use of the barrel-assembly as an aspirator or
transluminal extraction catheter for the removal of soft plaque or
mispositioned miniballs
[0224] XII8. Use of the barrel-assembly as an aspirator or
transluminal extraction catheter to retrieve biopsy samples
[0225] XII9. Rotation of muzzle-heads with unused barrel-tubes for
use as a guide-catheters
[0226] XII10. Delivery of a measured quantity of a liquid through a
service-channel
[0227] XII11. Delivery of a measured quantity of a gas through a
service-channel
[0228] XII12. Delivery of a measured quantity of a powder through a
service-channel
[0229] XII13. Midprocedural delivery of lubricant to the
muzzle-head
[0230] XIII. AIRGUNS
[0231] XIII1. Operational requirements
[0232] XIII2. Modification of commercial airguns
[0233] XIII2a. Simple airgun modified to allow limited
application
[0234] XIII2b. Simple airgun modified to allow wider
application
[0235] XIII2c. Control of propulsive force (exit velocity) by means
of a calibrated slide cover over a slit cut into the valve body
[0236] XIII2d. Docking stations for modified commercial airguns
[0237] XIII2e. Positioning modes of operation
[0238] XIII2e(1). Positioning with a simple pipe
[0239] XIII2e(2). Automated positioning with a radial discharge
barrel-assembly
[0240] XIII3. DEDICATED INTERVENTIONAL AIRGUNS
[0241] XIII3a. Operational requirements
[0242] XIII3b. Interventional airgun with liquid
vaporization-upon-release cartridge or compressed gas cylinder
connected directly to the valve body inlet suitable for use over a
range of exit velocities (forces of penetration) in quick
succession with moderate redundancy as to points of control over
discharge
[0243] XIII3c. Interventional airgun suitable for procedures
involving the treatment of different tissues to different depths in
quick succession with redundant points of control to adjust the
exit velocity
[0244] XIII3d. Interventional airgun with multiple exit velocity
control points for quick midprocedural adjustment, using rotary
magazine clips, and with an automatic positional control system
suitable for implanting the wall of a blood vessel
[0245] XIII3e. Linear positioning stage or table airgun mount
[0246] XIII3f. Positioning of the barrel-assembly with the linear
positioning table and turret-motor
[0247] XIII3f(1). Type and efficiency of control
[0248] XIII3f(2). Airgun control panel
[0249] XIII3f(3). Relation of control panels to the turret-motor
and airgun linear positioning table axes, to discharge, and to one
another
[0250] XIII3f(4). Automatic close-formation pattern
implantation
[0251] XIII4. Pairing of barrel-assembly and airgun
[0252] XII15. Remote controls
[0253] XIV. MODES OF FAILURE
[0254] XIV1. Failure to properly discharge
[0255] XIV2. Shallow termination into the lumen wall or other
tissue of the trajectory
[0256] XIV3. Perforations
[0257] XIV4. Jamming
[0258] XIV5. Premature follow-on discharge
[0259] XIV6. Endothelial cling and seizure
[0260] XIV7. Radial projection unit lift-platform malfunction
[0261] XIV8. Entry of a miniball into the bloodstream
[0262] XV. ARCUATE STAYS
[0263] XV1. Medication or radiation (nonstent), and
medication-coated stays
[0264] XV2. Arcuate stent-stays (stent-ribs) for use with magnetic
stent-jackets
[0265] XV3. Structure of stays
[0266] XV4. Partially and completely absorbed stays
[0267] XV5. Circumstances dissuading or recommending the use of
stays
[0268] XV6. Stays coated with a heat-activated (-melted,
-denatured) tissue adhesive-hardener, or binder-fixative
[0269] XV7. Stays coated with a solid protein solder coating and
cyanoacrylate cement
[0270] XV8. Use of cement and solder coated stays
[0271] XV9. Specification of cyanoacrylate tissue sealants and
bonding agents
[0272] XV10. Practitioner preference for cyanoacrylate tissue
sealant
[0273] XVI. STAY INSERTION TOOLS
[0274] XVI1. Stay insertion tool structure
[0275] XVI2. Stay insertion tool inmate stay recall (retraction)
and recovery electromagnet
[0276] XVI3. Stay insertion tool inmate tissue sealant and/or
medication delivery line
[0277] XVI4. Sealing of stay insertion incisions
[0278] XVI4a. Cement-before insertion (cement-ahead operation)
[0279] XVI4b. Sealant cartridges and sealants (adhesives)
[0280] XVI4c. Mechanism for adjustment in stay insertion tool
ejection cycle inmate cement delivery Interval
[0281] XVI4d. Control over the quantity of fluid discharged
[0282] XVI4e. Mechanism for switching from cement-ahead to
cement-follower operation
[0283] XVI5. Stay insertion tool with pivoting base
[0284] XVI6. Butt-pad with retractable slitting edge
[0285] XVII. Stay insertion tool-inserts and extension devices
[0286] XVI8. Use of multiple component adhesives with a stay
insertion tool
[0287] XVI9. Powered stay insertion tool holder for the attachment
of medication or tissue sealant syringes whether single, dual, or
multi-chambered as supplied, for tool slave-follower or independent
use
[0288] XVI9a. Use of commercial syringes and extension tubes
[0289] XVI9b. Avoidance of remote syringe placement and long
adhesive delivery lines
[0290] XVI9c. STAY INSERTION TOOL AUXILIARY SYRINGES
[0291] XVI9c(1). Control of auxiliary syringes
[0292] XVI9c(2). Tissue sealant syringe holder (holding frame) and
attachment
[0293] XVI9c(3). Structure of tissue sealant syringe holder
[0294] XVI9c(4). Stay insertion tool auxiliary syringe holding
frame attachment
[0295] XVI9c(5). Connection of the holding frame to the stay
insertion tool
[0296] XVI9c(6). Supporting arm and connecting cable
[0297] XVI9c(7). Control of auxiliary syringe eject-ahead or
eject-after with determinate timing
[0298] XVI9c(8). Independent and subordinated control of a stay
insertion tool auxiliary syringe holding Frame
[0299] XVI10. BINDING OF LINES AND CABLES ALONGSIDE THE STAY
INSERTION TOOL
[0300] XVI10a. Uses of stay insertion tool mounting clips and
bands
[0301] XVI10b. Use of stay insertion tool side mounting clips to
juxtaposition (fasten alongside) an endoscope
[0302] XVI10c. Use of stay insertion tool side mounting clips to
juxtaposition (fasten alongside) a vacuum (aspiration, suction)
line
[0303] XVI10d. Use of stay insertion tool side mounting clips to
juxtaposition (fasten alongside) a CO2 cylinder or cold air gun
line
[0304] XVI11. USE OF STAY INSERTION TOOL
[0305] XVII. TESTING AND TESTS
[0306] XVII1. Need of a means for testing the resistance to
puncture, perforation, and delamination of tissue requiring
treatment
[0307] XVII2. Midprocedural preinsertion testing
[0308] XVII3. Confirmation of terminus
[0309] XVII4. In situ test on endoluminal approach for
susceptibility of the ductus wall to puncture, penetration, and
perforation
[0310] XVII5. In situ test on endoluminal approach for intra- or
inter-laminar separation (delamination, laminar avulsion)
[0311] XVII6. Endoluminal approach test for intra- or inter-laminar
separation following the insertion of a test miniball
[0312] XVII7. In situ test on extraluminal approach for intra- or
inter-laminar separation (delamination, avulsion)
[0313] XVII8. In situ test on endoluminal approach for intra- or
inter-laminar separation following the insertion of a test
miniball
[0314] XVII9. In situ test on extraluminal approach for resistance
to centrifugal pull-through
[0315] XVII10. Interconvertibility of results among tests
[0316] XVII11. In situ muzzle-head adhesion test
[0317] XVIII. Followup examination
[0318] XIX. STERILIZATION
[0319] XX. EXEMPLARY CHANNEL OF CONTROL IN A FULLY IMPLANTED
AMBULATORY ADAPTIVE HIERARCHICAL CONTROL SYSTEM FOR AUTOMATIC
RESPONSE TO A COMORBID CONDITION
[0320] XXI. FULLY IMPLANTED AMBULATORY ADAPTIVE HIERARCHICAL
CONTROL SYSTEMS FOR AUTOMATIC RESPONSE TO A COMORBID CONDITION
[0321] XXII. GLOSSARY OF TERMS
[0322] CLAIMS
[0323] ABSTRACT OF THE DISCLOSURE
BACKGROUND OF THE INVENTION
1. Field of the invention
[0324] The apparatus and methods to be described are intended for
use by veterinary specialists, pulmonologists, interventional
radiologists and cardiologists, cardiovascular, thoracic, and
neurological surgeons, gastroenterologists, and urologists to:
[0325] 1. Target medication and/or therapeutic substances into the
wall surrounding a lumen by radially directed or side-looking
injection from within the lumen, with retention by radially outward
attraction by a magnetized jacket, or by embedding tiny implants
within this or any other diseased tissue. Few drugs released into
the circulation have a natural affinity for the organ or tissue
intended as iodine has for the thyroid gland. Instead, the drug is
delivered to all the tissues of the body at the dose required to
treat the intended organ or tissue, even though exposure to the
drug of other tissue may be harmful. This is usually the cause of
adverse side effects, drug-drug, and drug-food interactions.
Moreover, when not targeted, efficacy necessitates that the dose
required be much larger and therefore more costly. Accordingly, one
object here is to provide means that allow squarely targeting a
specific organ, segment along a tubular anatomical structure, or
tissue.
[0326] 2. Ablate diseased and/or obstructive tissue from or
angioplasty the walls surrounding a bodily conduit, that is, the
passageway or lumen through a tubular anatomical structure, whether
that of a blood vessel, a duct, ureter, vas deferens, fallopian
tube, the gut, trachea, or a bronchus, for example, any of which
may be properly referred to as a vas, vessel, ductus, duct, canal,
or channel
[0327] 3. Position increasingly magnetized spherules, stays,
impasse-, or stent-jackets along a ductus in the antegrade
(anterograde) direction to draw and concentrate ferromagnetic
carrier-bound drugs from the passing circulation into the lumen
wall.
[0328] 4. Position these minute implants so as to target a specific
segment of a ductus or an organ, and if necessary.
[0329] 5. Embed implants containing sufficient ferromagnetic
material to serve as the intraductal component of an extraluminal
stent, where any or all of the foregoing functions can be
accomplished in any combination or sequence with single entry.
Small implants consisting almost entirely of medication can be
implanted in any tissue, to include the wall surrounding a lumen,
or can be positionally stabilized inside the lumen alongside a
diseased segment.
[0330] 6. Target drugs within supply conduits, such as arteries, by
suspending these as magnetically susceptible carrier
superparamagnetic nanoparticles or microparticles within a magnetic
jacket encircling the conduit, either a stent-jacket, or if to be
extracted to the perivascular space, an impasse-jacket, so that the
drug or drugs are drawn against or into the lesioned wall of the
lumen, or if contained within a miniball or microsphere shell but
not inseparably bound to the magnetically susceptible particles, or
ferro co-bound, the drug or drugs are released into the lumen. More
specifically, as will be described, when a drug is to be directly
delivered to the target organ, tissue, or segment along a tubular
anatomical structure through the circulation, uptake from an
infused or injected drug dispersed in a ferrofluid is through a
port at the body surface, thence through a fluid line leading to
the tissue with uptake by detention at the target segment and and
absorption through the endothelium or urothelium, for example, by
means of an impasse-jacket. An electromagnetized jacket allows the
drug to be drawn into the intima or suburothelium, for example.
When the drug is to be delivered to an organ, for example, delivery
is into the lumen of the organ blood supply through a ductus
side-entry jacket or if into the parenchyma, a nonjacketing
side-entry connector as described in copending applications
specified below.
[0331] 7. Where the substance, usually a drug must be prevented
from further circulation, position a final impasse-jacket
downstream or at the outflow, such as venous, of the target organ
to suspend within the lumen a reversal agent (counteractant,
antidote, neutralizing agent) to the drug released by the upstream
implant or by positioning increasingly magnetized implants about
the lumen to truncate its continued flow to nontargeted tissue.
[0332] Presented here will be a form of magnetic stenting which is
fundamentally superior to any endoluminal or intravascular magnetic
stent, or any endoluminal stent intended to be attracted to a
magnetic field generated from outside the stented conduit, or
ductus. More specifically, the type stent described is superior to
any endouminal stent magnetic or not. That is, whether the lumen of
a blood vessel, the airway, the digestive tract, urogenital (or
urinogenital), tract, or an endocrine duct, magnetically
susceptible endoluminal stents and coiled stents positioned inside
the lumen to achieve the pushing outward of the wall surrounding an
inflamed, constricted, or obstructed lumen when attracted to an
extraluminal magnet are fundamentally inferior to the intramural,
or infixed within the lumen wall, means described herein. The
reasons for this superiority are sufficiently pertinent from a
medical standpoint as to warrant preliminary comment.
[0333] First, where intramurally positioned implants, ordinarily
distributed uniformly about the lumen wall for attraction to a
magnetized jacket surrounding the ductus or conduit, uniformly
expand the lumen radially outward in all directions, endoluminal
magnetic stents only pull at the substrate conduit or ductus in the
direction of attraction. The tiny magnetically susceptible
intramural implants used to impart patency to a constricted lumen,
which can incorporate or be coated with medication of any kind, are
positioned entirely about the lumen wall, and rather than drawn to
an extracorporeal magnet, are surrounded by an implanted foam-lined
jacket (collar, mantle) in immediate contact with the substrate
ductus. When spherical, these implants are referred to as
miniballs; when band (strip, tang)-shaped, the term used is stays.
In comparison, endoluminal magnetic stents are incapable of
treating the radial asymmetries or eccentricities characteristic of
angiosclerotic lesions or plaques discriminately, instead covering
over unaffected radii about the arterial wall.
[0334] The jacket is magnetized perpendicularly to the long axis of
the conduit or ductus and may be rolled from magnetized stainless
steel sheet, or as shown in FIGS. 2 thru 6, comprise a polymeric
base-tube having small permanent magnets or electromagnets affixed
thereto. When drawn to an outside magnet, an endoluminal magnetic
stent is drawn up against the ipsilateral luminal wall, imposing a
significant indenting force thereupon in excess of the outward
force an endoluminal stent must exert to prevent migration under
any circumstances. This is a potential source of serious
complications that a stent having no part within the lumen can
never present. Recovery of an endoluminal stent is by reentry and
surgical cut-down, which is why once placed, an endoluminal stent
is removed only when removal cannot be avoided.
[0335] An endoluminal stent has one means for avoiding
migration--protrusion into the surrounding lumen lining. The struts
of a scaffold type stent or the wire of a coiled stent must be made
thinner to further protrude into the lining Properly placed, an
intraluminal stent cannot migrate. The intraluminal component is
embedded within the lumen wall, and located outside the substrate
ductus or vessel, the magnetized stent-jacket can be fixed in
position in several ways. Small optional suture loops or eyelets
integral with the jacket allow suture to be passed through for
fixation to neighboring tissue.
[0336] When suture is riveted or already connected by suture loops
to the ends of the jacket (referred to as end-ties) as
manufactured, the suture can be used as indicated, wrapped about
the substrate ductus beyond the jacket margins, or both. Where
vasotonic is pronounced or the activity of the patient is conducive
to displacement, one or two outrigger or dummy collars, shown as
parts of an impasse-jacket described below in sections 12 entitled
Concept of the Impasse-jacket and I15 entitled Miniball and
Ferrofluid-impassable Jackets, or Impasse-jackets can be provided,
and both the stent-jacket proper and the outriggers can be fastened
as stated with suture.
[0337] Magnetically susceptible endoluminal stents are usually
widely open pitched (space wound, open wound) non-overwound coils,
that is, single turn or single wrap coils having wide gaps between
the consecutive turns (winds, wraps), precluding drug elution as a
partially remediating measure for the chronic irritation caused. A
distinct irritant, endoluminal stents in the vascular tree--of all
kinds, but especially those susceptible to a magnetic field--have
the potential not only to stimulate intimal hyperplasia leading to
restenosis, but accelerate atherosclerosis, better endoluminal
stents ameliorating the problem with drugs such as everolimus.
[0338] Rapamycin-derived drugs such as everolimus are used
primarily as immunosuppressants, of special benefit with an
endoluminal stent, which to prevent migration, must maintain firm
contact with the surrounding luminal wall, thereby provoking a
foreign body adverse tissue reaction or immune response. Even in a
nonallergic patient, such reactions are unavoidable; however, the
contact area with the surrounding tissue of miniballs and stays is
much less than that of an endoluminal stent, and these too can be
coated with drugs such as everolimus. In most cases, the immune
system will encapsulate the protrusive surfaces of a foreign body
such as an endoluminal stent or an intraluminal implant in a
vascular and collagenous fibrous capsule, the process known as the
foreign body response or foreign body granuloma.
[0339] However, formation of this isolating layer is typically
50-200 micrometers in thickness--enough to isolate an implant
chemically, but even with the high level of motion about a stent to
stimulate an increase in this thickness, not enough to afford
sufficient protection against the mechanical forces imposed upon
the tissue in contact with the stent (see, for example, de la
Oliva, N., Navarro, X., and Del Valle, J. 2018. "Time Course Study
of Long-term Biocompatibility and Foreign Body Reaction to
Intraneural Polyimide-based Implants," Journal of Biomedical
Materials Research. Part A 106(3):746-757; Klopfleisch, R. and
Jung, F. 2017. "The Pathology of the Foreign Body Reaction Against
Biomaterials," Journal of Biomedical Materials Research. Part A
105(3):927-940; Wang, Y., Vaddiraju, S., Gu, B.,
Papadimitrakopoulos, F., and Burgess, D. J. 2015. "Foreign Body
Reaction to Implantable Biosensors: Effects of Tissue Trauma and
Implant Size," Journal of Diabetes Science and Technology
9(5):966-977; Wazen, R. M., Currey, J. A., Guo, H., Brunski, J. B.,
Helms, J. A., and Nanci, A. 2013. "Micromotion-induced Strain
Fields Influence Early Stages of repair at Bone-implant
Interfaces," Acta Biomaterialia 9(5):6663-6674; Morais, J. M.,
Papadimitrakopoulos, F., and Burgess, D. J. 2010.
"Biomaterials/Tissue Interactions: Possible Solutions to Overcome
Foreign Body Response," American Association of Pharmaceutical
Scientists Journal 12(2): 188-196).
[0340] It is during the granulation and maturation phase leading up
to formation of the capsule--variable in duration depending upon
the material used, but generally taking about 2 to 4 weeks--that
the tissue in contact with the stent is especially vulnerable.
"Biomaterial surface properties play an important role in
modulating the foreign body reaction in the first two to four weeks
following implantation of a medical device, even though the foreign
body reaction at the tissue/material interface is present for the
in vivo lifetime of the medical device." (Anderson, J. M.,
Rodriguez, A., and Chang, D. T. 2008. "Foreign Body Reaction to
Biomaterials," Seminars in Immunology 20(2):86-100).
[0341] However, the fibrous tissue with an endoluminal stent will
be continuous over the length of the stent, interfering with
endothelial or urothelial function, and only the endoluminal stent
will remain within the lumen to pose the risk of migration and
present a distinct obstruction to any later transluminal procedure.
Before fibrous encapsulation forms, a stent placed within any
native lumen presents the potential for ischemia-inducing
intramedial protrusion, which can lead to an erosion, incision, and
fistulation (fistulization) responsive to continuous irritation of
physiologically active tissue. That this is virtually certain with
a direct blow and impossible when no stent is in the lumen is
clear.
[0342] Endoluminal stents are potentially more injurious than
medicinal treatment without stenting; local adaptation
notwithstanding, continued force of indentation, aggravated by the
normal intrinsic vasotonic and pulsatile or peristaltic motility of
the conduit increases the risk of infection, interferes with,
impairs the function of, and injures the endothelium, urothelium,
or other lining, thereby interfering with normal endothelial,
urothelial, or digestive enzymatic function, and creating the risks
of fistulation and perforation. In the arterial tree, such risk
includes incisions, aneurysm, pseudoaneurysm, and migration. The
guide wire used to deliver an endoluminal stent to the target level
is itself a source of numerous complications to include
perforations, fracture, and migration, to which the blunt or
bull-nosed leading tip of the delivery means described here--a
barrel-assembly--is not. To recover an errant endoluminal stent or
guidewire can involve greater surgical risk than the risk the stent
was placed to ameliorate.
[0343] Endothelial dysfunction is central in causing coronary
artery disease and other expressions of chronic arterial
inflammation. In any situation where the force of the magnetic
field would adversely extract spherical implants, wide band- or
tongue-shaped implants are used, the means for the insertion
thereof--stay insertion tools--described herein. Where an
endoluminal stent is in contact with the surrounding lumen wall, it
blocks not only endothelial effusion into the lumen of
prostacyclin, endothelin, and locally controlling angiotensin-II,
but the vasodilator nitric oxide. Also denied over the contact area
is access to the passing luminal contents, those native, blood,
urine, endocrine secretion, gametes, or food, enzymes, hormones,
other proteins, and therewith, nonendogenous agents, meaning
medication.
[0344] Whether coiled or scaffold in type, when attracted by an
external magnet, an endoluminal stent is pulled further into the
lumen wall. In marked contrast to such endoluminal stents,
intramural stents lie outside the lumen; the magnetically
susceptible component comprises a uniformly spaced grouping of tiny
implants infixed within the lumen wall where the nonliving
connective tissue elastic laminae protect the other laminae (tissue
layers, tunics) consisting of living cells which comprise the lumen
wall from injury. Migration or dislodgement a serious risk with any
endoluminal stent, such is not possible when no stent is inside the
lumen. That the tiny intramurally positioned susceptible implants
are uniformly distributed over the area stented is of fundamental
significance.
[0345] Disposed thus, attraction by an external magnet, rather than
concentrating the attractive force over a small contact area
between the stent and the lumen wall, uniformly lifts the wall
abaxially or outward as a continuous sheet over the completely
surrounding area of the stent rather than concentrating a force of
indentation in excess of that imposed by an endoluminal stent under
any circumstances over a restricted area, increasing the risks of
injury and incision. Such a stent can, however, accommodate
eccentric or asymmetrical lesions according to the distribution of
the implants. In most cases, however, the jacket entirely
surrounding the substrate native conduit or ductus, the magnetic
attraction is uniformly exerted entirely about the conduit or
ductus. Accordingly, rather than for the stent to be forcibly
attracted into the lumen wall, intramurally positioned implants
lift the lumen wall uniformly round and about toward the
surrounding magnetized jacket.
[0346] In the trachea, where an intramural magnetically susceptible
stent as described herein is superior to the considerably traumatic
conventional surgical procedure for correction, an endoluminal
stent obstructs mucociliary clearance, facilitating the
accumulation of debris, increasing the risk of infection. In a
neonate, in whom tracheomalacia infrequently appears as a condition
encountered when the tracheal cartilages remain premature at birth,
the short-term placement of an endoluminal stent when there is a
risk of suffocation then prudent. However, in veterinary practice,
where any of numerous animals in whom tracheal collapse is
progressive and the conventional remedy is surgical, an endoluminal
stent that must be placed in lieu of surgery because the animal is
too debilitated to tolerate the procedure must remain in place
indefinitely as an increasingly injurious obtrusion.
[0347] That a magnetic intraluminal stent avoids both the problems
of an endotracheal stent and the need for critically more traumatic
surgery is clear. Unless springy with restorative force such that
the contralateral side of the stent remains in contact with the
contralateral wall, the contralateral side of the stent is drawn
away from the contralateral wall and further into the lumen. This
adaxial shifting only increases interference with free luminal
flow-through of any endoluminal stent. Even when remaining in flush
contact with the contralateral wall, numerous problems arise from
the presence in a native lumen of a foreign object, interference if
not prevention of subsequent transluminal treatment not the least
of these. For this reason, the advantage in an extraluminal stent
increases in proportion to the probability that the patient will
require a followup transluminal intervention.
[0348] The incorporation of magnetically susceptible matter in an
implant allows the implant not only to attracted to a magnet, but
when placed in a radiofrequency alternated magnetic field, allows
the implant to be heated. Thermoplastic ablation by impregnating a
neoplasm with susceptible implants and placing the patient in such
a field has long been standard practice. The application of heat of
value in numerous other contexts--site specifically controlling
drugs or surgical adhesives, for example--scaffold or coiled
endoluminal stents heat the lumen wall not uniformly, but
disproportionately where the struts or turns are in direct contact
with the lumen wall. Moreover, even though the lesion to be heated
is eccentric, such stents are limited to the application of heat in
this disjointed way without deviation from radial or rotational
symmetry, thus heating sectors of the ductus not beneficially and
perhaps adversely affected thus. By contrast, intramural stenting
allows discretionary eccentric or radially asymmetrical
heating.
[0349] The miniballs, or tiny spherules, and bands, or stays,
referred to herein can consist of magnetically susceptible matter,
usually encapsulated, medication, radiation emitting `seeds,` or
any of these in combination. To impart targetability to medication
spherules, for example, a magnetized ductus side-entry jacket or
nonjacketing connector is positioned at the target site, and
magnetically susceptible matter, usually magnetite, maghemite, or
iron powder, added to the spherules. Ferrofluids conveying
magnetically carried drugs ratioactive or not can thus be steered
to the treatment site without the need for intrinsic affinity, such
as that of iodine for the thyroid gland. All drugs harbor adverse
side effects and have toxic dose limits. Two types of drugs in
particular are, however, more injurious when admitted into the
general circulation.
[0350] These are immunosuppressives, which expose the patient to
infection, and anticancer drugs, which are toxic to normal as well
as malignant tissue. Minimally invasive and minor surgical
procedures make possible the implantation of magnetically
susceptible drug-carrier releasing and attracting implants that
allow treatments intermediate between medical management and open
surgery. More specifically, by allowing the circumscription of
target tissue for the delivery of drugs or other therapeutic
substances, minor surgery to place such implants can be used to
significantly expand the reach of medical management. The methods
described herein represent a level of treatment intermediate
between medical management and surgery, that of medical surgery, or
surgery to enable or facilitate medical management.
[0351] The presupposition that surgery should always be considered
the last resort so that the administration of drugs, all
potentially harmful, to temporarily alleviate the symptoms of
chronic disorders on a long-term if not life-long basis is superior
therapy compared to performing a one-time relatively safe surgical
procedure is often micsonceived. Examples are many and apply to
almost if not all drugs used thus, the most common being:
[0352] a. Antacids in lieu of endoscopic repair of an hiatus
hernia, and/or highly selective vagotomy, or the placement of a
special esophagogastric collar about the lower esophageal
sphincter, or transoral incisionless endoscopic fundoplication
(see, for example, Fass, R. 2017. "An Overview of Transoral
Incisionless Fundoplication and Magnetic Sphincter Augmentation for
GERD," Gastroenterology and Hepatology (New York, N.Y.)
13(1):50-52; Trad, K. S., Fox, M. A., Simoni, G., Shughoury, A. B.,
Mavrelis, P. G., and 3 others 2017. "Transoral Fundoplication
Offers Durable Symptom Control for Chronic GERD: 3-year Report from
the TEMPO [Transoral incisionless fundoplication] EsophyX vs
Medical Proton Pump Inhibitor Open Label Trial] Randomized Trial
with a Crossover Arm," Surgical Endoscopy 31(6):2498-2508; Huang,
X., Chen, S., Zhao, H., Zeng, X., Lian, J., Tseng, Y., and Chen, J.
2017. "Efficacy of Transoral Incisionless Fundoplication (TIF) for
the Treatment of GERD: A Systematic Review with Meta-analysis,"
Surgical Endoscopy 31(3):1032-1044; Stefanidis, G., Viazis, N.,
Kotsikoros, N., and Tsoukalas, N., Lala, E., and 3 others 2017.
"Long-term Benefit of Transoral Incisionless Fundoplication Using
the Esophyx Device for the Management of Gastroesophageal Reflux
Disease Responsive to Medical Therapy," Diseases of the Esophagus
30(3):1-8; Fass, R. 2017. "An Overview of Transoral Incisionless
Fundoplication and Magnetic Sphincter Augmentation for GERD,"
Gastroenterology and Hepatology (New York, N.Y.) 13(1):50-52; Trad,
K. S., Barnes, W. E., Simoni, G., Shughoury, A. B., Mavrelis, P.
G., and 4 others 2015. "Transoral Incisionless Fundoplication
Effective in Eliminating GERD Symptoms in Partial Responders to
Proton Pump Inhibitor Therapy at 6 Months: the TEMPO Randomized
Clinical Trial," Surgical Innovation 22(1):26-40; Bonavina, L.,
Saino, G., Lipham, J. C., and Demeester, T. R. 2013. "LINX(.RTM.)
Reflux Management System in Chronic Gastroesophageal Reflux: A
Novel Effective Technology for Restoring the Natural Barrier to
Reflux," Therapeutic Advances in Gastroenterology 6(4):261-268) to
alleviate gastroesophageal reflux or to cure an ulcer, which at the
least allows the administration of such drugs to be significantly
reduced in dose and frequency.
[0353] Chronic use of antacids can lead to achlorhydria, the
absence, or hypochlorhydria, a deficiency, of hydrochloric acid in
the gastric juice, defeating an important mechanism of the immune
system for eradicating pathogenic microbiota from food, which can
lead to bacterial overgrowth of the small intestine, interfering
with the absorption of iron and other nutrients, and promoting
intestinal metaplasia, degenerative conversion of the stomach
lining to resemble that of the small intestine, or atrophic
gastritis. The overgrowth is likely to lead to gastric infection,
the interference with iron absorption to iron deficiency anemia,
possibly pica, the interference with vitamin B.sub.3 (niacin)
absorption to pellagra, and the metaplasia to additional
malabsorption such as the loss of parietal cells, hence, gastric
intrinsic factor needed to absorb vitamin B.sub.12 (cobalamin).
[0354] This then can lead to pernicious anemia, megaloblastic
anemia, and gastric adenocarcinoma, as well as open the way for
numerous additional gastrointestinal, neuropsychiatric, and
systemic disorders. Untreated, this degenerative cascade results in
death. However, the administration of antibiotics to compensate for
infectious consequences of the reduction in stomach acidity also
destroys beneficial intestinal microbiota (dysbiosis,
dysbacteriosis), risking leaky gut syndrome. This also allows
pathogenic microbiota unaffected by the antibiotic to survive,
reproduce, and become more resistant to the antibiotic, a
misapplication of antibiotics that contributes to the growing
problem of drug resistant pathogens, and may prompt the
administration of probiotics to repopulate the gut with beneficial
microbiota.
[0355] Especially in patients with health problems, probiotics
occasionally cause adverse sequelae, to include undesirable gene
transfer, digestive problems, systemic infections, equivocally,
endocarditis, bloating, flatulence, in larger doses, diarrhea, an
increase in gastroesophageal reflux, and/or other problems (see,
for example, Aaron, J. G., Sobieszczyk, M. E., Weiner, S. D.,
Whittier, S., and Lowy, F. D. 2017. "Lactobacillus rhamnosus
Endocarditis after Upper Endoscopy," Open Forum Infectious Diseases
4(2):ofx085; Isidro, R. A., Lopez, A., Cruz, M. L., Gonzalez Tones,
M. I., Chompre, G., Isidro, A. A., and Appleyard, C. B. 2017. "The
Probiotic VSL#3 Modulates Colonic Macrophages, Inflammation, and
Microflora in Acute Trinitrobenzene Sulfonic Acid Colitis," Journal
of Histochemistry and Cytochemistry 65(8):445-461; Encarnacion, C.
O., Loranger, A. M., Bharatkumar, A. G., and Almassi, G. H. 2016.
"Bacterial Endocarditis Caused by Lactobacillus acidophilus Leading
to Rupture of Sinus of Valsalva Aneurysm," Texas Heart Institute
Journal 43(2):161-164.; Doron, S. and Snydman, D. R. 2015. "Risk
and Safety of Probiotics," Clinical Infectious Diseases 60
Supplement 2:S129-S134; Verna, E. C. and Lucak, S. 2010. "Use of
Probiotics in Gastrointestinal Disorders: What to Recommend?,"
Therapeutic Advances in Gastroenterology 3(5):307-319; Marteau, P.
and Seksik, P. 2004. "Tolerance of Probiotics and Prebiotics,"
Journal of Clinical Gastroenterology 38(6 Supplement):S67-S69).
[0356] Upon discontinuation after daily use, nonsteroidal antacids
such as proton pump inhibitors educe pronounced rebound acid
hypersecretion sensed as `heartburn` (see, for example, Zdilla, M.
J. 2015. "Metformin with Either Histamine H2-receptor Antagonists
or Proton Pump Inhibitors: A Polypharmacy Recipe for Neuropathy via
Vitamin B.sub.12 Depletion," Clinical Diabetes 33(2):90-95; Reimer,
C., Sondergaard, B., Hilsted, L., and Bytzer, P. 2009. "Proton-pump
Inhibitor Therapy Induces Acid-related Symptoms in Healthy
Volunteers after Withdrawal of Therapy," Gastroenterology
137(1):80-87, 87.e1; Nwokolo, C. U., Smith, J. T., Sawyerr, A. M.,
and Pounder, R. E. 1991. "Rebound Intragastric Hyperacidity After
Abrupt Withdrawal of Histamine H2 Receptor Blockade," Gut
32(12):1455-1460).
[0357] Proton pump inhibitors such as omeprazole have been linked
to the development of dementia (see, for example, Clouston, S. A.
P., Shapira, O., Kotov, R., Lei, L., Waszczuk, M., Bromet, E. J.,
and Luft, B. J. 2017. "Proton Pump Inhibitors and the Risk of
Severe Cognitive Impairment: The Role of Posttraumatic Stress
Disorder," Alzheimers and Dementia (New York, N.Y.) 3(4):579-583;
Wijarnpreecha, K., Thongprayoon, C., Panjawatanan, P., and
Ungprasert, P. 2016. "Proton Pump Inhibitors and Risk of Dementia,"
Annals of Translational Medicine 4(12):240), Gomm, W., von Holt,
K., Thome, F., Broich, K., Maier, W., and 3 others 2016.
"Association of Proton Pump Inhibitors with Risk of Dementia: A
Pharmacoepidemiological Claims Data Analysis," Journal of the
American Medical Association Neurology 73(4):410-416;
hypomagnesemia and kidney disease (see, for example,
Toth-Manikowski, S. and Grams, M. E. 2017. "Proton Pump Inhibitors
and Kidney Disease--GI Upset for the Nephrologist?," Kidney
International Reports 2(3):297-301; Cheungpasitporn, W.,
Thongprayoon, C., Kittanamongkolchai, W., Srivali, N., Edmonds, P.
J. and 4 others 2015. "Proton Pump Inhibitors linked to
Hypomagnesemia: A Systematic Review and Meta-analysis of
Observational Studies," Renal Failure 37(7):1237-1241), . . . .
"Clostridium difficile infection, community-acquired pneumonia,
fractures of the hip and spine." (Toth-Manikowski, S. and Grams, M.
E. 2017, Op cit., cites references for each).
[0358] As to C. difficile (see, for example, Oshima, T., Wu, L.,
Li, M., Fukui, H., Watari, J., and Miwa H. 2018. "Magnitude and
Direction of the Association Between Clostridium difficile
Infection and Proton Pump Inhibitors in Adults and Pediatric
Patients: A Systematic Review and Meta-analysis," Journal of
Gastroenterology 53(1):84-94; Trifan, A., Stanciu, C., Girleanu,
I., Stoica, O. C., Singeap, A. M., and 4 others 2017. "Proton Pump
Inhibitors Therapy and Risk of Clostridium difficile Infection:
Systematic Review and Meta-analysis," World Journal of
Gastroenterology 23(35):6500-6515; Scarpignato, C., Gatta, L.,
Zullo, A., Blandizzi, C.; with 9 collaborators 2016. "Effective and
Safe Proton Pump Inhibitor Therapy in Acid-related Diseases--A
position Paper Addressing Benefits and Potential Harms of Acid
Suppression," BioMed Central Medicine 14(1): 179).
[0359] Histamine H.sub.2 receptor antagonists (cimetidine,
ranitidine, famotidine, nizatidine) risk numerous adverse side
effects and drug interactions (see, for example, Upadhyay, K. J.,
Parmar, S. J. 1, Parikh, R. P. 1, Gauswami, P. K., Dadhaniya, N.,
and Surela, A. 2015. "Intravenous Ranitidine: Rapid Bolus Can Lead
to Cardiac Arrest," Journal of Pharmacology and
Pharmacotherapeutics 6(2):100-102; Zdilla, M. J. 2015. "Metformin
with Either Histamine H2-receptor Antagonists or Proton Pump
Inhibitors: A Polypharmacy Recipe for Neuropathy via Vitamin B12
Depletion," Clinical Diabetes 33(2):90-95; Lee, T. H., Vega, K. J.,
and El Khoury, J. G. 2010. "Ranitidine Induced Hepatitis," Journal
of Gastrointestinal and Liver Disease 19(3):337-338; Ramrakhiani,
S., Brunt, E. M., and Bacon, B. R. 1998. "Possible Cholestatic
Injury from Ranitidine with a Review of the Literature," American
Journal of Gastroenterology 93(5):822-826; Garcia Rodriguez, L. A.,
Wallander, M. A., and Stricker, B. H. 1997. "The Risk of Acute
Liver Injury Associated with Cimetidine and Other Acid-suppressing
Anti-ulcer Drugs," British Journal of Clinical Pharmacology
43(2):183-188; Kallal, S. M. and Lee, M. 1996. "Thrombotic
Thrombo-cytopenic Purpura Associated with Histamine H2-receptor
Antagonist Therapy," Western Journal of Medicine 164(5):446-448;
Garcia Rodriguez, L. A. and Jick, H. 1994. "Risk of Gynaecomastia
Associated with Cimetidine, Omeprazole, and Other Antiulcer Drugs,"
British Medical Journal (clinical research) 308(6927):503-506;
Sabesin, S. M. 1993. "Safety Issues Relating to Long-term Treatment
with Histamine H2-receptor Antagonists," Alimentary Pharmacology
and Therapeutics 7 Supplement 2:35-40; Vial, T., Goubier, C.,
Bergeret, A., Cabrera, F., Evreux, J. C., and Descotes, J. 1991.
"Side Effects of Ranitidine," Drug Safety 6(2):94-117; Andersen, M.
and Schou, J. S. 1991. "Adverse Effects of Ulcer drugs before and
after Release of Cimetidine, Ranitidine and Sucralfate for
Over-the-counter Sale," (in Danish with abstract in English at
Pubmed), Ugeskrift for Laeger [Weekly Journal for Physicians]
153(20):1410-1413; Berardi, R. R., Tankanow, R. M., and Nostrant,
T. T. 1988. "Comparison of Famotidine with Cimetidine and
Ranitidine," Clinical Pharmacy 7(4):271-284; Aymard, J. P., Aymard,
B., Netter, P., Bannwarth, B., Trechot, P., and Streiff, F. 1988.
"Haematological Adverse Effects of Histamine H2-receptor
Antagonists," Medical Toxicology and Adverse Drug Experience
3(6):430-448; Lewis, J. H. 1987. "Hepatic Effects of Drugs Used in
the Treatment of Peptic Ulcer Disease," American Journal of
Gastroenterology 82(10):987-1003; Schunack, W. 1987. "What are the
Differences Between the H2-receptor Antagonists?," Alimentary
Pharmacology and Therapeutics 1 Supplement 1:493S-503S; Black, M.
1987. "Hepatotoxic and Hepatoprotective Potential of Histamine
(H2)-receptor Antagonists," American Journal of Medicine
83(6A):68-75; Sax, M. J. 1987. "Clinically Important Adverse
Effects and Drug Interactions with H2-receptor Antagonists: An
Update," Pharmacotherapy 7(6 Part 2):110S-115S; Penston, J. and
Wormsley, K. G. 1986. "Adverse Reactions and Interactions with
H2-receptor Antagonists," Medical Toxicology 1(3):192-216; Kirch,
W., Spahn, H., Kohler, H., and Mutschler, E. 1983. "Accumulation
and Adverse Effects of Metoprolol and Propranolol after Concurrent
Administration of Cimetidine," Archives of Toxicology. Supplement
6:379-383; Hughes, J. D., Reed, W. D., and Serjeant, C. S. 1983.
"Mental Confusion Associated with Ranitidine," Medical Journal of
Australia 2(1):12-13; Tosi, S., and Cagnoli, M. 1982. "Painful
Gynecomastia with Ranitidine," Lancet 2(8290):160; Schifman, C.
1983. "Gynecomastia and Bradycardia: Side Effects of Ranitidine?,"
Clinical Pharmacy 2(3):209; Camarri, E., Chirone, E., Fanteria, G.,
and Zocchi, M. 1982. "Ranitidine-induced Bradycardia," Lancet
2(8290): 160).
[0360] Patient specific allergic reactions such as urticaria, or
hives, dyspnea, and facial swelling, for example, aside, famotidine
is less prone to provoke adverse side effects than other drugs in
its class but is not without its own risks (see, for example,
Gupta, N., Patel, C., and Panda, M. 2009. "Hepatitis Following
Famotidine: A Case Report," Cases Journal 2009 2(1):89; Scheinfeld,
N., Wesson, K., Perry, P., and Weinberg, J. 2003. "Acute
Generalized Exanthematous Pustulosis Resembling Toxic Epidermal
Necrolysis Caused by Famotidine," Acta Dermato-venereologica
83(1):76-77; Marcus, E. L., Clarfield, A. M., Kleinman, Y., Bits,
H., Darmon, D., Da'as, N. 2002. "Agranulocytosis Associated with
Initiation of Famotidine Therapy," Annals of Pharmacotherapy
36(2):267-271; von Einsiedel, R. W., Roesch-Ely, D., Diebold, K.,
Sartor, K., Mundt, C., and Bergemann, N. 2002. "H(2)-histamine
Antagonist (Famotidine) Induced Adverse CNS Reactions with
Long-standing Secondary Mania and Epileptic Seizures,"
Pharmacopsychiatry 35(4):152-154; Yuan, R. Y., Kao, C. R., Sheu, J.
J., Chen, C. H., and Ho, C. S. 2001. "Delirium Following a Switch
from Cimetidine to Famotidine," Annals of Pharmacotherapy
35(9):1045-1048; Rodgers, P. T. and Brengel, G. R. 1998.
"Famotidine-associated Mental Status Changes," Pharmacotherapy
18(2):404-407; Odeh, M. and Oliven, A. 1998. "Central Nervous
System Reactions Associated with Famotidine: Report of Five Cases,"
Journal of Clinical Gastroenterology 27(3):253-254; Brunner, M.,
Vardarman, E., Goldermann, R., Goerz, G., Niederau, D., Merk, H.
F., and Scharffetter-Kochanek, K. 1995. "Toxic Epidermal Necrolysis
(Lyell Syndrome) Following Famotidine Administration," British
Journal of Dermatology 133(5):814-815; Ament, P. W., Roth, J. D.,
and Fox, C. J. 1994. "Famotidine-induced Mixed Hepatocellular
Jaundice," Annals of Pharmacotherapy 28(1):40-42; Ahmad, S. 1991.
"Famotidine and Cardiac Arrhythmia," Drug Intelligence and Clinical
Pharmacy: The Annals of Pharmacotherapy 25(3):315; Norwood, J.,
Smith, T. M., and Stein, D. S. 1990. "Famotidine and Hyperpyrexia,"
Annals of Internal Medicine 112(8):632; Henann, N. E., Carpenter,
D. U., and Janda, S. M. 1988. "Famotidine-associated Mental
Confusion in Elderly Patients," Drug Intelligence and Clinical
Pharmacy 22(12):976-978). Famotidine induces urticaria in those
allergic but has value in the treatment of urticaria (Fedorowicz,
Z., van Zuuren, E. J., and Hu, N. 2012. "Histamine H2-receptor
Antagonists for Urticaria," Cochrane Database of Systematic Reviews
(3):CD008596; Watson, N. T., Weiss, E. L., and Harter, P. M. 2000.
"Famotidine in the Treatment of Acute Urticaria," Clinical and
Experimental Dermatology 25(3):186-189).
[0361] Famotidine may be of greater value for off-label than
conventional use (Joe, S., Kim, E., Park, J., Lee, D., Son, J., and
Kim, H. 2017. "Famotidine-induced Reversal of Meperidine-related
Serotonin Syndrome: A Case Report" Korean Journal of Anesthesiology
70(2):221-223; Meskanen, K., Ekelund, H., Laitinen, J., Neuvonen,
P. J., Haukka, J., Panula, P., and Ekelund, J. 2013. "A Randomized
Clinical Trial of Histamine 2 Receptor Antagonism in
Treatment-resistant Schizophrenia," Journal of Clinical
Psychopharmacology 33(4):472-478; Rosenberg, P. B., Rosse, R. B.,
John, S. K., Kendrick, K., Fay-McCarthy, M., and 4 others 1996.
"Smooth Pursuit Eye Movements in the Evaluation of Famotidine
Adjunctive Therapy of Schizophrenia: A Preliminary Report,"
Clinical Neuropharmacology 19(3):276-281).
[0362] b. Nasal decongestants in lieu of balloon rhinoplasty or
outfracture of the swollen lower turbinates with widening of the
nasal passages through cautery. Oxymetazoline hydrochloride, for
example, is associated with numerous systemic side effects (see,
for example, Dokuyucu, R., Gokce, H., Sahan, M., Sefil, F., Tas, Z.
A., and 4 others 2015. "Systemic Side Effects of Locally Used
Oxymetazoline," International Journal of Clinical and Experimental
Medicine 8(2):2674-2678; Ramey, J. T., Bailen, E., and Lockey, R.
F. 2006. "Rhinitis Medicamentosa," Journal of Investigational
Allergology and Clinical Immunology 16(3):148-155; Graf, P. 1997.
"Rhinitis Medicamentosa: Aspects of Pathophysiology and Treatment,"
Allergy 52(40 Supplement):28-34; Graf, P. and Hallen, H. 1996.
"Effect on the Nasal Mucosa of Long-term Treatment with
Oxymetazoline, Benzalkonium Chloride, and Placebo Nasal Sprays,"
Laryngoscope 106(5 Part 1):605-609; Graf, P., Hallen, H., and Juto,
J. E. 1995. "Four-week Use of Oxymetazoline Nasal Spray (Nezeril)
Once Daily at Night Induces Rebound Swelling and Nasal
Hyperreactivity," Acta Otolaryngologica 115(1):71-75).
[0363] Most nasal decongestants provoke rebound vasodilative
congestive swelling of the mucosa, or rhinitis medicamentosa. Other
side effects of al adrenergic receptor agonists and .alpha.2
adrenergic receptor partial agonists such as oxymetazoline,
xylometazoline, naphazoline, and phenylephrine are drowsiness,
epistaxis (nosebleed), rebound inflammation, nasal dryness, and
some effect on hearing (Teixeira, M. S., Alper, C. M., Martin, B.
S., Helal, N., Doyle, B. M., and Doyle, W. J. 2016. "Oxymetazoline
Applied Topically to the Nasal Mucosa Decreases Trans-mucosal
Nitrous Oxide Exchange for the Middle Ear," Annals of Otology,
Rhinology, and Laryngology 125(5):400-407). Phenylephrine
hydrochloride can cause bradycardia. (Farkas, A., Dempster, J., and
Coker, S. J. 2008. "Importance of Vagally Mediated Bradycardia for
the Induction of Torsade de Pointes in an In Vivo Model," British
Journal of Pharmacology 154(5): 958-970).
[0364] Steroid nasal sprays can cause burning, itching, and dryness
of the nasal and pharyngeal mucosae, cephalalgia, or headache,
epistaxis, or nosebleed, running nose, sneezing, immunosuppression
leading to infection, serious effects on vision such as glaucoma,
hives, angioedema, anaphylaxis, dysmenorrhea, and endocrine
problems such as weight gain (Mangan, T. 2017. "Side Effects of
Nasal Steroid Spray," at
https://www.livestrong.com/article/234291-types-of-prescription-nasal-spr-
ays/). Discrete organs can be targeted with any drug that can be
prepared for delivery to and release by an impasse-jacket placed at
an inlet to the organ such as the renal artery to target a kidney
or other inlet such as a ureter to target the bladder. If take-up
of the drug by the target organ would leave a potentially harmful
residue pass into the outflow, then an impasse-jacket at the outlet
is used to release a reversal agent, thus circumscribing a
delimited portion of the circulation and its territory for exposure
to the drug.
[0365] These examples are cited to make the general point that
minor surgery should not perfunctorily be relegated to the course
of last resort, without regard to remedies for these conditions
specifically using means described herein, conventional measures
for alleviating hyperacidity and nasal congestion without the use
of drugs specified above. Endogenous histamine type H.sub.2 is a
causative agent for hyperchlorhydria (hyperacidity, `heat burn`)
(see, for example, Mejia, A. and Kraft, W. K. 2009. "Acid Peptic
Diseases: Pharmacological Approach to Treatment," Expert Review of
Clinical Pharmacology 2(3):295-314; Scarpignato, C., Pelosini, I.,
and Di Mario, F. 2006. "Acid Suppression Therapy: Where Do We Go
From Here?," Digestive Diseases (Basel, Switzerland) 24(1-2):11-46;
Beales, I. L. 2002. "Easy as 1, 2, 3? Histamine Receptors and
Gastric Acid," Gut 50(6):747-748).
[0366] Histamine Types H.sub.1 and H.sub.3 are the causative agents
for swollen nasal membranes (see, for example, Bosma, R., Witt, G.,
Vaas, L. A. I., Josimovic, I., Gribbon, P., and 3 others 2017. "The
Target Residence Time of Antihistamines Determines Their Antagonism
of the G Protein-Coupled Histamine H1 Receptor," Frontiers in
Pharmacology 8:667; Procopiou, P. A., Ford, A. J., Gore, P. M.,
Looker, B. E., Hodgson, S. T., and 7 others 2017. "Design of
Phthalazinone Amide Histamine H1 Receptor Antagonists for Use in
Rhinitis," American Chemical Society Medicinal Chemistry Letters
8(5):577-581; Khanfar, M. A., Affini, A., Lutsenko, K., Nikolic,
K., Butini, S., and Stark, H. 2016. "Multiple Targeting Approaches
on Histamine H3 Receptor Antagonists," Frontiers in Neuroscience
10:201; Slack, R. J., Russell, L. J., Hall, D. A., Luttmann, M. A.,
Ford, A. J., and 5 others 2011. "Pharmacological Characterization
of GSK1004723, a Novel, Long-acting Antagonist at Histamine H(1)
and H(3) Receptors," British Journal of Pharmacology
164(6):1627-1641; Lieberman, P. 2009. "The Role of Antihistamines
in the Treatment of Vasomotor Rhinitis," World Allergy Organization
Journal 2(8):156-161; Taylor-Clark, T., Sodha, R., Warner, B., and
Foreman, J. 2005. "Histamine Receptors that Influence Blockage of
the Normal Human Nasal Airway," British Journal of Pharmacology
144(6):867-874).
[0367] For most conditions, the means described herein provide
alternatives to the administration of potentially harmful drugs on
a long-term if not lifelong basis. Less serious conditions, where
surgical access to the nidal site or sites is relatively direct,
are treated by connecting a jacket for the directly targeted
release of drugs, for example, into one or more supply arteries
proximate to the affected organ or tissue. Alternatively, a tissue
surface connector is affixed to the surface of the affected organ
or tissue so that the styloid device it mounts, such as a hollow
needle, angioscope, charge coupled device camera (charge coupled
device camera, or fluorescence lifetime imaging microscopy (see
below in section 4d(3), entitled Nontumefacient Enabled Attainment
of Implantable Ductus-intramural Thickness), intravascular
ultrasound probe, high intensity forcused ultrasound probe, or
excimer laser, is stably oriented, or aimed, within the substrate
organ or tissue. Therapeutic and diagnostic apparatus using a
nonimplanable conrol console are attached to the implant system
through a socket in the body surface port.
[0368] The placement of these involves relatively minor surgery
performed under local anesthesia. More serious conditions warrant
more intricate surgery under general anesthesia; however, in all
cases, the fact that drugs and other treatment modalities are
directly targeted means that adverse side effects are minimized if
not eliminated. This may make possible the problem-free use of long
available drugs to which many patients have an adverse reaction
over time and for which certain patients have little if any
tolerance when the drugs are systemically circulated. Similar to
opting for the use of nontargeted, systemically circulated drugs is
the use of appliances that pose the risk of complications.
[0369] c. In veterinary practice, for example, the postponing of
surgery, instead opting for the use of a tracheal stent to suppress
the symptoms associated with tracheal collapse (the progressive
loss in resilience of the tracheal cartilage rings) interferes with
mucociliary clearance, promoting the accumulation of mucus and the
inviting of infection. In this case, however, the conventional
surgical remedy calls for extensive incision, dissection, and
stitching. While requiring general anesthesia, the alternative
remedy set forth herein, delineated below in sections VII2c(1)(a)
and VII2c(1)(b), for the alleviation of tracheal collapse involves
minimal surgery. This condition, which presents in animals, is not
the same as the trachemalacia occasionally seen in an infant The
latter spontaneously resolves of its own accord as the tracheal
rings, premature and lacking in resilience at birth, develop
resilience so that no surgical remedy should be attempted. In this
instance, the short-term placement of a stent with close monitoring
of the condition is justified to eliminate the risk of
suffocation.
[0370] d. Another example of the eventual harm which can accrue if
effective measures are not taken at the outset is the placement of
a conventional stent or stent-graft to correct a more severe
coarctation of the aorta where surgical reconstruction ab initio,
while itself subject to adverse sequelae, is currently still the
more reliable approach for long term repair, especially in the
young if not too ill to tolerate the surgery, then justifying the
placement of a covered stent or stent-graft (see, for example,
Promphan, W. and Qureshi, S. A. 2016. "What Interventional
Cardiologists are Still Leaving to the Surgeons?," Frontiers in
Pediatrics 4:59; Torok, R. D., Campbell, M. J., Fleming, G. A., and
Hill, K. D. 2015. "Coarctation of the Aorta: Management from
Infancy to Adulthood," World Journal of Cardiology 7(11):765-775;
Bruckheimer, E. and Pedra, C. A. C. 2013. "Stenting Options for
Coarctation of the Aorta," Interventional Cardiology Clinics
2(1):115-129; Luijendijk, P., Bouma, B. J., Groenink, M.,
Boekholdt, M., Hazekamp, M. G., and 4 others 2012. "Surgical Versus
Percutaneous Treatment of Aortic Coarctation: New Standards in An
Era of Transcatheter Repair," Expert Review of Cardiovascular
Therapy 10(12):1517-1531; Kische, S., Schneider, H., Akin, I.,
Ortak, J., Rehders, T. C., Chatterjee, T., Nienaber, C. A., and
Ince, H. 2010. "Technique of Interventional Repair in Adult Aortic
Coarctation," Journal of Vascular Surgery 51(6):1550-1559; Egan, M.
and Holzer, R. J. 2009. "Comparing Balloon Angioplasty, Stenting
and Surgery in the Treatment of Aortic Coarctation," Expert Review
of Cardiovascular Therapy 7(11):1401-1412), would prove more
sufficient and durable.
[0371] Often effective for avoiding a more radical coarctoplasty or
coarterectomy in an adult, in a neonate or infant, conventional
covered self-expanding stents or stent grafts may not hold fast and
migrate as the aorta grows, migration occasionally occuring in an
adult as well (see, for example, Rad, E. M., Mortezaeian, H.,
Pouraliakbar, H. R., and Hijazi, Z. M. 2017. "Pitfalls of Stenting
Coarctation of an Angulated Right Circumflex Aortic Arch in
Goldenhar Syndrome," Annals of Pediatric Cardiology 10(2):194-196;
Jha, N. K., Tofeig, M., Kumar, R. A., ElTahir, A., Athar, S. M.,
AlHakami, A., Khan, A., and Khan, M. D. 2016. "Stent Dilatation of
Atretic Aortic Coarctation in an Adult--Case report and Literature
Review," Journal of Cardiothoracic Surgery 11:10; Forbes, T. J. and
Gowda, S. T. 2014. "Intravascular Stent Therapy for Coarctation of
the Aorta," Methodist Debakey Cardiovascular Journal 10(2):82-87;
Ang, H. L., Lim, C. W., Hia, C., Yip, J., and Quek, S. C. 2014.
"Coarctation of the Aorta: Nonsurgical Treatment Using Stent
Implantation," Singapore Medical Journal 55(6):302-304; Ringel, R.
E., Vincent, J., Jenkins, K. J., Gauvreau, K., Moses, H., Lofgren,
K., and Usmani, K. 2013. "Acute Outcome of Stent Therapy for
Coarctation of the Aorta: Results of the Coarctation of the Aorta
Stent Trial," Catheterization and Cardiovascular Interventions
82(4):503-510; Yaylali, Y. T., Evrengul, H., and Uludag, B. 2013.
"Successful Management of a Proximally Migrated Stent in a
Middle-aged Woman with Unnoticed Native Aortic Coarctation,"
International Journal of Cardiology 168(1):e19-21; Kannan, B. R.
and Srinivasan, M. 2012. "Stent Migration During Transcatheter
Management of Coarctation of Aorta," Catheterization and
Cardiovascular Interventions 79(3):408-413; Nikolov, D., Grigorova,
V., Petrov, I., and Ivanov, V. 2011. "Emergency Surgical
Intervention After Unsuccessful Percutaneous Transluminal
Angioplasty and Stenting of Aortic Coarctation," Interactive
Cardiovascular and Thoracic Surgery 13(1):98-100; Forbes, T. J.,
Garekar, S., Amin, Z., Zahn, E. M., Nykanen, D., and 19 others
2007. "Procedural Results and Acute Complications in Stenting
Native and Recurrent Coarctation of the Aorta in Patients over 4
Years of Age: A Multi-institutional Study," Catheterization and
Cardiovascular Interventions 70(2):276-285; Karl, T. R. 2007.
"Surgery is the Best Treatment for Primary Coarctation in the
Majority of Cases," Journal of Cardiovascular Medicine (Hagerstown,
Md.) 8(1):50-56). Coarctation is further addressed below.
[0372] While in an adult, growth is not a risk for dislodgement so
that stenting is more dependable than in an infant, in the young,
stenting may be chosen as a bridging (holding, salvaging) strategy
until the patient, usually very ill, is ready to undergo
reconstructive surgery (see, for example, Bugeja, J., Cutajar, D.,
Zahra, C., Parascandalo, R., Grech, V., and DeGiovanni, J. V. 2016.
"Aortic Stenting for Neonatal Coarctation of the Aorta--When Should
this be Considered?," Images in Paediatric Cardiology 18(3):1-4;
Haponiuk, I., Chojnicki, M., Steffens, M., Jaworski, R.,
Szofer-Sendrowska, A., and 5 others 2013. "Miniinvasive
Interventional Bridge to Major Surgical Repair of Critical Aortic
Coarctation in a Newborn with Severe Multiorgan Failure"
Wideochirurgia Inne Techniki Maloinwazyjne [Videosurgery and Other
Miniinvasive Techniques] 8(3):244-248; Sreeram, I., Sreeram, N.,
and Bennink, G. 2012. "Palliative Stent Implantation for
Coarctation in Neonates and Young Infants," Annals of Pediatric
Cardiology 5(2): 145-150).
[0373] Other growth-related problems threaten the young patient
following surgical repair: especially when ductal (ductus
arteriosus) tissue is not completely resected, surgery is not
necessarily free of numerous growth-related adverse sequelae
(Torok, R. D., Campbell, M. J., Fleming, G. A., and Hill, K. D.
2015. "Coarctation of the Aorta: Management from Infancy to
Adulthood," World Journal of Cardiology 7(11):765-775; Vergales, J.
E., Gangemi, J. J., Rhueban, K. S., and Lim, D. S. 2013.
"Coarctation of the Aorta--The Current State of Surgical and
transcatheter Therapies," Current Cardiology Reviews 9(3):211-219;
Rosenthal, E. 2005. "Coarctation of the Aorta from Fetus to Adult:
Curable Condition or Life Long Disease Process?," Heart (journal of
the British Cardiac Society) 91(11):1495-1502; Head, C. E., Jowett,
V. C., Sharland, G. K., and Simpson, J. M. 2005. "Timing of
Presentation and Postnatal Outcome of Infants Suspected of Having
Coarctation of the Aorta During Fetal Life," Heart (journal of the
British Cardiac Society) 91(8):1070-1074; Backer, C. L., Mavroudis,
C., Zias, E. A., Amin, Z., and Weigel, T. J. 1998. "Repair of
Coarctation with Resection and Extended End-to-end Anastomosis,"
Annals of Thoracic Surgery 66(4):1365-1371; Van Son, J. A., Falk,
V., Schneider, P., Smedts, F., and Mohr, F. W. 1997. "Repair of
Coarctation of the Aorta in Neonates and Young Infants," Journal of
Cardiac Surgery 12(3):139-146; Rajasinghe, H. A., Reddy, V. M., van
Son, J. A., Black, M. D., McElhinney, D. B., Brook, M. M., and
Hanley, F. L. 1996. "Coarctation Repair Using End-to-side
Anastomosis of Descending Aorta to Proximal Aortic Arch," Annals of
Thoracic Surgery 61(3):840-844; Rubay, J. E., Sluysmans, T.,
Alexandrescu, V., Khelif, K., Moulin, D., Vliers, A., Jaumin, P.,
and Chalant, C. H. 1992. "Surgical Repair of Coarctation of the
Aorta in Infants Under One Year of Age. Long-term Results in 146
Patients Comparing Subclavian Flap Angioplasty and Modified
End-to-end Anastomosis," Journal of Cardiovascular Surgery (Turin,
Italy) 33(2):216-222), this in addition to the risks besides
abnormal blood pressure following surgery for adults (see, for
example, Bruckheimer, E. and Pedra, C. A. C. 2013, Op cit.).
[0374] e. Yet another example of the eventual harm which accrues if
effective measures are not taken at the outset is reconstruction of
a severely malformed neonate or infant heart when a replacement is
available. No repair of more complex congenital heart defects
however skilled achieves normal circulatory function, surgical
remediation often properly relegated to a bridging procedure until
a replacement heart can be found. So long as development continues
with a badly defective heart, the lack of normal circulation is
propagated throughout the body as a chronic hypoxia that results in
progressive multiple, indeed global, organ damage, severely
affecting the brain, liver, and kidneys, and a life limited by a
continuous and inexorable increase in left ventricular load that
comes with growth to add to the intrinsic antecedent dysfunction
until left ventricular overload can no longer be withstood.
[0375] That following replacement, using the means described
herein, immunosuppressive, antimicrobial, and anti-inflammatory
drugs can be automatically and directly targeted to the transplant
substantially diminishes the quality of life-degrading need for the
patient to self-administer these for life, and the fact that drug
delivery is directly pipe-targeted to the transplant with or
without a background systemic dose means that the severe side
effects of immunosuppressives with increased exposure to infection
is minimized if not eliminated.
[0376] Prompt replacement of a univentricular or otherwise severely
malformed and not adequately repairable heart in the young has
inadequate durability. Although less so with increasing
pharmaceutical experience, remedial procedures only alter, but do
not dispel, the pulmonary vascular resistance and hypertension that
makes the condition harmful and precarious. By instantly and
precisely responding to alterations in adverse pulmonary arterial
indicia with new and improved drugs, an automatic prosthetic
disorder response system should significantly lessen hypertension
at every stage in treatment, extend the periods between successive
stages in surgical correction, and if not accomplished at the
outset, transplantation and if still necessary, retransplantation.
The overall result is an extended and less oppressive life.
[0377] A completed Fontan repair ameliorates but does not alleviate
the key problem of pulmonary vascular resistance, and its
reinstatement following transplantation combined with growth will
eventually necessitate retransplantation (see, for example, Hauck,
A., Porta, N., Lestrud, S., and Berger, S. 2017. "The Pulmonary
Circulation in the Single Ventricle Patient," Children (Basel,
Switzerland) 4(8). pii: E71; Egbe, A. C., Connolly. H. M., Miranda,
W. R., Ammash, N. M., Hagler, D. J., Veldtman, G. R., and Borlaug,
B. A. 2017. "Hemodynamics of Fontan Failure: The Role of Pulmonary
Vascular Disease," Circulation. Heart Failure 10(12). pii: e004515;
Kindel, S. J. and Everitt, M. D. 2016. "A Contemporary Review of
Paediatric Heart Transplantation and Mechanical Circulatory
Support," Cardiology in the Young 26(5):851-859; Fredenburg, T. B.,
Johnson, T. R., and Cohen, M. D. 2011. "The Fontan Procedure:
Anatomy, Complications, and Manifestations of Failure,"
Radiographics 31(2):453-463; Maxwell, B. G., Sheikh, A. Y.,
Ajuba-Iwuji, C. C., Heitmiller, E. S., and Vricella, L. A. 2015.
"Pulmonary Vascular Resistance Index and Mortality after Paediatric
Heart Transplant," Cardiology in the Young 25(6):1141-1147; Snarr,
B. S., Paridon, S. M., Rychik, J., and Goldberg, D. J. 2015.
"Pulmonary Vasodilator Therapy in the Failing Fontan Circulation:
Rationale and Efficacy," Cardiology in the Young 25(8):1489-1492;
Michielon, G., Carotti, A., Pongiglione, G., Cogo, P., anf Parisi,
F. 2011. "Orthotopic Heart Transplantation in Patients with
Univentricular Physiology," Current Cardiology Reviews 7(2):85-91;
Gazit, A. Z. and Canter, C. E. 2011. "Impact of Pulmonary Vascular
Resistances in Heart Transplantation for Congenital Heart Disease,"
Current Cardiology Reviews 7(2):59-66).
[0378] Even with banding of the pulmonary artery to suppress
hypertension and a superior cavopulmonary connection operation,
leaving otherwise untreated a univentricular heart results in the
progressive degradation and maldevelopment of all organ systems
from the moment of birth (Al-Dairy, A., Dehaki, M. G., Omrani, G.,
Sadeghpour, A., Jalali, A. H., and 3 others 2017. "The Outcomes of
Superior Cavopulmonary Connection Operation: A Single Center
Experience," Brazilian Journal of Cardiovascular Surgery
32(6):503-507; Kalantre, A., Sunil, G. S., and Kumar, R. K. 2016.
"Pulmonary Venous Hypertension May Allow Delayed Palliation of
Single Ventricle Physiology with Pulmonary Hypertension," Annals of
Pediatric Cardiology 9(2):147-152; Alsoufi, B., McCracken, C.,
Schlosser, B., Sachdeva, R., Well, A., and 3 others 2016. "Outcomes
of Multistage Palliation of Infants with Functional Single
Ventricle and Heterotaxy Syndrome," Journal of Thoracic and
Cardiovascular Surgery 151(5):1369-1377.e2; Alsoufi, B., Manlhiot,
C., Ehrlich, A., Oster, M., Kogon, B., and 4 others 2015. "Results
of Palliation with an Initial Pulmonary Artery Band in Patients
with Single Ventricle Associated with Unrestricted Pulmonary Blood
Flow," Journal of Thoracic and Cardiovascular Surgery
149(1):213-220; Schwartz, M. C., Sullivan, L., Cohen, M. S., Russo,
P., John, A. S., Guo, R., Guttenberg, M., and Rand, E. B. 2012.
"Hepatic Pathology May Develop Before the Fontan Operation in
Children with Functional Single Ventricle: An Autopsy Study,"
Journal of Thoracic and Cardiovascular Surgery 143(4):904-909;
Alsoufi, B., Manlhiot, C., Awan, A., Alfadley, F., Al-Ahmadi, M.,
and 3 others 2012. "Current Outcomes of the Glenn Bidirectional
Cavopulmonary Connection for Single Ventricle Palliation," European
Journal of Cardiothoracic Surgery 42(1):42-49; Bove, E. L. 1986.
"Cardiac Surgery for the Adolescent with Univentricular Heart,"
Pediatrician 13(4):171-179), essentially forcing either a Fontan
procedure to ameliorate but not eliminate the progressive
degradation, or if a replacement heart is available, a heart
transplantation, which conventionally supported, substantially
discontinues most organ system breakdown and provided the baby is
closely monitored and the drug regimen adhered to, reduces but does
not eliminate pulmonary vascular resistance.
[0379] Because it responds instantly and precisely at any time in
any place with repair, usually a Fontan, modified, or hybrid,
superior cavopulmonary connection operation (see, for example,
Al-Dairy, A., Dehaki, M. G., Omrani, G., Sadeghpour, A., Jalali, A.
H., and 3 others 2017, Op cit.), or septation procedure to divide
the one functional ventricle (Bove, E. L. 1986, Op cit.), or a
transplant, an automatic adaptive disorder response system as
delineated in sections XX and XX below will provide better support
before or with any resolution.
[0380] More specifically, the controlling program adaptive, once
placed in a prenate or neonate, the system will continuously
optimize medicinal therapy at every succeeding stage in the disease
and its treatment, to include that preceding any treatment, that
following preliminary procedures such as banding and cavopulmonary
connection, and any measures applied thereafter to include
Fontan-preparatory (Norwood, Hemi-Fontan, or Glenn) (see, for
example, Liang, F., Senzaki, H., Yin, Z., Fan, Y., Sughimoto, K.,
and Liu, H. 2013. "Transient Hemodynamic Changes upon Changing a
BCPA [bidirectional cavopulmonary (Glenn) anastomosis] into a TCPC
[total cavopulmonary connection] in Staged Fontan Operation: A
Computational Model Study," Scientific World Journal 2013:486815;
Podzolkov, V. P., Zelenikin, M. M., Yurlov, I. A., Kovalev, D. V.,
Mchedlishvili, K. A., Putiato, N. A., and Zaets, S. B. 2011.
"Immediate Results of Bidirectional Cavopulmonary Anastomosis and
Fontan Operations in Adults," Interactive Cardiovascular and
Thoracic Surgery 12(2):141-145; Giglia, T. M. and Humpl, T. 2010.
"Preoperative Pulmonary Hemodynamics and Assessment of Operability:
Is There a Pulmonary Vascular Resistance that Precludes Cardiac
Operation?," Pediatric Critical Care Medicine 11(2
Supplement):S57-S69), then a Fontan, and with the means described
herein, best followed by a transplant.
[0381] That is, the will adaptively dispense medication to optimize
circulation before repair or replacement. Quick to adapt, it
therefore better sustains the pre- and post-Fontan or other repair
in preparation for a transplant, and then better sustains the
transplant, extending the time until--at the present state in
development of transplant support--the effects of residual
pulmonary hypertension necessitate retransplantation. In favorable
circumstances and with optimized pharmacy, the need for a
retransplantation might be avoided.
[0382] Deferral of transplantation following a Fontan repair can
actually preclude transplantation (see, for example, Dijkstra, H.,
Wolff, D., van Melle, J. P., Bartelds, B., Willems, T. P., and 6
others 2017. "Diminished Liver Microperfusion in Fontan Patients: A
Biexponential DWI [iffusion-weighted imaging] Study," Public
Library of Science One 12(3):e0173149; Greenway, S. C., Crossland,
D. S., Hudson, M., Martin, S. R., Myers, R. P., and 3 others 2016.
"Fontan-associated Liver Disease: Implications for Heart
Transplantation," Journal of Heart and Lung Transplantation
35(1):26-33; Michielon, G., Carotti, A., Pongiglione, G., Cogo, P.,
and Parisi, F. 2011, Op cit.--"It is erroneous to assume that
because a Fontan patient is alive, the pulmonary vascular
resistance is low enough to tolerate an OHT [orthotopic heart
transplantation];" see also Giglia, T. M. and Humpl, T. 2010, Op
cit.). Moreover, the combination of nontargeted immunosuppressive
and pulmonary impairment promotes infection (Michielon, G.,
Carotti, A., Pongiglione, G., Cogo, P., anf Parisi, F. 2011, Op
cit.--"Intolerance to Fontan physiology with prolonged pleural
effusions, ascites, lymphopenia and protein dispersion can
predispose to life-threatening infections that are triggered by
post-OHT immunosuppression").
[0383] While it is possible to support a Fontan procedure with such
an implanted automatic adaptive response system to deliver
respiration and circulation supportive drugs (see, for example,
Dasse, K. A., Petit, P. C., Fine, D. H., and Vasquez, G. 2017.
Method and Apparatus for Administering Nitric Oxide with
Supplemental Drugs, World Intellectual Property Organization Patent
Application 2017/116,776; Oldenburger, N. J., Mank, A., Etnel, J.,
Takkenberg, J. J., and Helbing, W. A. 2016. "Drug Therapy in the
Prevention of Failure of the Fontan Circulation: A Systematic
Review," Cardiology in the Young 26(5):842-850; Mori, H., Park, I.
S., Yamagishi, H. 1, Nakamura, M., Ishikawa, S., and 5 others 2016.
"Sildenafil Reduces Pulmonary Vascular Resistance in Single
Ventricular Physiology," International Journal of Cardiology
221:122-127; Butts, R. J., Chowdhury, S. M., Baker, G. H.,
Bandisode, V., Savage, A. J., and Atz, A. M. 2016. "Effect of
Sildenafil on Pressure-volume Loop Measures of Ventricular Function
in Fontan Patients," Pediatric Cardiology 37(1):184-191; Bosc, L.
V. G., Maston, L. D., and Rest, T. 2016. Compositions and Methods
for Treatment of Pulmonary Hypertension, World Intellectual
Property Organization Patent Application 2016/176,399; Coyle, K.,
Coyle, D., Blouin, J., Lee, K., Jabr, M. F., and 4 others 2016.
"Cost Effectiveness of First-line Oral Therapies for Pulmonary
Arterial Hypertension: A Modelling Study," PharmacoEconomics
34(5):509-520; Hebert, A., Mikkelsen, U. R., Thilen, U., Idorn, L.,
Jensen, A. S., and 4 others 2014. "Bosentan Improves Exercise
Capacity in Adolescents and Adults after Fontan Operation: The
TEMPO (Treatment with Endothelin Receptor Antagonist in Fontan
Patients, a Randomized, Placebo-controlled, Double-blind Study
Measuring Peak Oxygen Consumption) Study," Circulation
130(23):2021-2030; Chen, Y. F., Jowett, S., Barton, P., Malottki,
K., Hyde, C., and 5 others 2009. "Clinical and Cost-effectiveness
of Epoprostenol, Iloprost, Bosentan, Sitaxentan and Sildenafil for
Pulmonary Arterial Hypertension within Their Licensed Indications:
A Systematic Review and Economic Evaluation," Health Technology
Assessment (Winchester, England) 13(49):1-320; Simmonds, J., Burch,
M., Dawkins, H., and Tsang, V. 2008. "Heart Transplantation after
Congenital Heart Surgery: Improving Results and Future Goals,"
European Journal of Cardiothoracic Surgery 34(2):313-317), when a
replacement heart is available, it is preferable to replace the
defective heart ab initio.
[0384] However, if a replacement is unavailable, since it is likely
that the speed and accuracy of response will better sustain a
Fontan until a replacement heart becomes available, the system is
best implanted to support the Fontan and then reprogrammed to
support the new heart. Such reprogramming does not include the drug
response to the pulmonary hypertension induced by the
pretransplantation pulmonary vascular resistance, to which the
adaptive system will spontaneously adjust, but rather the addition
of immunosuppressives and anti-inflammatories, for example, as
pertinent.
[0385] An automatic prosthetic disorder response system as
delineated below in sections XX entitled Exemplary Channel of
Control in a Fully Implanted Ambulatory Adaptive Hierarchical
Control System for Automatic Response to a Comorbid Condition and
XXI entitled Fully Implanted Ambulatory Adaptive Hierarchical
Control Systems for Automatic Response to a Comorbid Condition in
combination with new and improved drugs for immunosuppression also
beneficiates transplantation otherwise jeopardized by two other key
deterrents--drug regimen noncompliance and imunosuppresive side
effects.
[0386] This is because the system directly pipe-targets the drugs
to the treatment site, sparing other organs and tissue--and regimen
noncompliance the second most significant cause of failure--because
it dispenses the drugs the moment the need therefor is reported by
the implanted sensors to the implanted microprocessor--anywhere,
anytime--in the middle of the night while the baby is asleep,
before the baby senses any experiential correlate, before there is
any realization of such need, and without a clinician present.
Equally important, the system adaptively dispenses the drugs on the
basis of the previous diagnostic-to-medication relationship data it
has accumulated, thus assuring not only immediate but theranostic
drug delivery under any circumstances.
[0387] More specifically, since the system is adaptive, this
applies with the system placed in the neonate or infant prior to
and following surgical repair, then following heart transplantation
if applicable, and in some cases, liver transplantation, the system
designed to remain in place with the ability to accommodate growth
for years. Some babies will require a replacement heart, liver, and
lungs, which should be staged over intervals sufficient for full
recovery. The sites of flexibility that allow for growth are
summarized below toward the end of section XXI, for example,
entitled Fully Implanted Ambulatory Adaptive Hierarchical Control
Systems for Automatic Response to a Comorbid Condition.
[0388] However, in contrast to attempts at surgical repair, prompt
transplantation with proper pharmaceutical management of pulmonary
vascular resistance better supports early development where a
nominally repaired and still defective heart does not, and later
transplantation of an inadequately repaired congenital heart can
never return to normal all other organ systems that had been left
to develop abnormally (see, for example, Kelly, C. J., Makropoulos,
A., Cordero-Grande, L., Hutter, J., Price, A., and 15 others 2017.
"Impaired Development of the Cerebral Cortex in Infants with
Congenital Heart Disease is Correlated to Reduced Cerebral Oxygen
Delivery," Scientific Reports 7(1):15088; Puelz, C., Acosta, S.,
Riviere, B., Penny, D. J., Brady, K. M., and Rusin, C. G. 2017. "A
Computational Study of the Fontan Circulation with Fenestration or
Hepatic Vein Exclusion," Computers in Biology and Medicine
89:405-418; Goldberg, D. J., Surrey, L. F., Glatz, A. C., Dodds,
K., O'Byrne, M. L., and 6 others 2017. "Hepatic Fibrosis is
Universal Following Fontan Operation, and Severity is Associated
with Time from Surgery: A Liver Biopsy and Hemodynamic Study,"
Journal of the American Heart Association 6(5); Dijkstra H., Wolff,
D., van Melle, J. P., Bartelds, B., Willems, T. P., and 6 others
2017, Op cit.; Ohuchi, H. 2017. "Where is the "Optimal" Fontan
Hemodynamics?," Korean Circulation Journal 47(6):842-857; Morton,
P. D., Korotcova, L., Lewis, B. K., Bhuvanendran, S., Ramachandra,
S. D., and 7 others 2017. "Abnormal Neurogenesis and Cortical
Growth in Congenital Heart Disease," Science Translational Medicine
9(374). pii: eaah7029; Fidai, A., Dallaire, F., Alvarez, N., Balon,
Y., Clegg, R., and 11 others 2017. "Non-invasive Investigations for
the Diagnosis of Fontan-associated Liver Disease in Pediatric and
Adult Fontan Patients," Frontiers in Cardiovascular Medicine 4:15;
Hilscher, M. B., Johnson, J. N., Cetta, F., Driscoll, D. J. 3,
Poterucha, J. J., and 3 others 2017. "Surveillance for Liver
Complications after the Fontan Procedure," Congenital Heart Disease
12(2):124-132; Oh, C., Youn, J. K., Han, J. W., Kim, G. B., Kim, H.
Y., and Jung, S. E. 2016. "Hepatocellular Carcinoma after the
Fontan Procedure in a 16-year-old Girl: A Case Report," Medicine
(Baltimore, Md.) 95(41):e4823; Josephus Jitta, D., Wagenaar, L. J.,
Mulder, B. J., Guichelaar, M., Bouman, D., and van Melle, J. P.
2016. "Three Cases of Hepatocellular Carcinoma in Fontan Patients:
Review of the Literature and Suggestions for Hepatic Screening,"
International Journal of Cardiology 206:21-26; Takuma, Y., Fukada,
Y., Iwadou, S., Miyatake, H., Uematsu, S., and 7 others 2016.
"Surgical Resection for Hepatocellular Carcinoma with Cardiac
Cirrhosis after the Fontan Procedure," Internal Medicine (Tokyo,
Japan) 55(22):3265-3272; Chen, B., Schreiber, R. A., Human, D. G.,
Potts, J. E., and Guttman, O. R. 2016. "Assessment of Liver
Stiffness in Pediatric Fontan Patients Using Transient
Elastography," Canadian Journal of Gastroenterology and Hepatology
2016:7125193; Wolff, D., van Melle, J. P., Dijkstra, H., Bartelds,
B., Willems, T. P., and 5 others 2016. "The Fontan Circulation and
the Liver: A Magnetic Resonance Diffusion-weighted Imaging Study,"
International Journal of Cardiology 202:595-600; Kwon, S., Scovel,
L., Yeh, M., Dorsey, D., Dembo, G., and 6 others 2015. "Surgical
Management of Hepatocellular Carcinoma after Fontan Procedure,"
Journal of Gastrointestinal Oncology 6(3):E55-E60; Wu, F. M.,
Jonas, M. M., Opotowsky, A. R., Harmon, A., Raza, R., and 6 others
2015. "Portal and Centrilobular Hepatic Fibrosis in Fontan
Circulation and Clinical Outcomes," Journal of Heart and Lung
Transplantation 2015 34(7):883-891; Assenza, G. E., Graham, D. A.,
Landzberg, M. J., Valente, A. M., Singh, M. N., and 6 others 2013.
"MELD-XI [Model for End-stage Liver Disease eXcluding International
Normalization Ratio score] Score and Cardiac Mortality or
Transplantation in Patients after Fontan Surgery," Heart (British
Cardiac Society) 99(7):491-496; Rychik, J., Veldtman, G., Rand, E.,
Russo, P., Rome, J. J., and 4 others 2012. "The Precarious State of
the Liver after a Fontan Operation: Summary of a Multidisciplinary
Symposium," Pediatric Cardiology 33(7):1001-1012; Goldberg, C. S.,
Mussatto, K., Licht, D., and Wernovsky, G. 2011. "Neurodevelopment
and Quality of Life for Children with Hypoplastic Left Heart
Syndrome: Current Knowns and Unknowns," Cardiology in the Young 21
Supplement 2:88-92; Ghaferi, A. A. and Hutchins, G. M. 2005.
"Progression of Liver Pathology in Patients Undergoing the Fontan
Procedure: Chronic Passive Congestion, Cardiac Cirrhosis, Hepatic
Adenoma, and Hepatocellular Carcinoma," Journal of Thoracic and
Cardiovascular Surgery 129(6): 1348-1352).
[0389] Nevertheless, the prompt replacement of a severely defective
heart in utero or shortly postpartum averts operative and
postoperative complications which can result from preceding
attempts at reconstruction, to include the adverse respiratory
effects of Fontan circulation, obscuring scarring, adhesions
(Lamour, J. M., Kanter, K. R., Naftel, D. C., Chrisant, M. R.,
Morrow, W. R., Clemson, B. S., and Kirklin, J. K. 2009. "The Effect
of Age, Diagnosis, and Previous Surgery in Children and Adults
Undergoing Heart Transplantation for Congenital Heart Disease,"
Journal of the American College of Cardiology 54(2):160-165), as
well as delay a proper correction as damage caused by faulty
circulation continues to accumulate, significantly increasing the
need while decreasing the prospects for successful transplantation
at a later time (see, for example, Alsoufi, B., Mahle, W. T.,
Manlhiot, C., Deshpande, S., Kogon, B., McCrindle, B. W., and
Kanter, K. 2016. "Outcomes of Heart Transplantation in Children
with Hypoplastic Left Heart Syndrome Previously Palliated with the
Norwood Procedure," Journal of Thoracic and Cardiovascular Surgery
151(1):167-175.el-e2; Schumacher, K. R. and Goldberg, D. J. 2016.
"Biomarkers and the Fontan Circulation," Journal of the American
Heart Association 5(1). pii: e002926; Lang, S. M., Frazier, E. A.,
and Collins, R. T. 2nd 2016. "Aortic Complications following
Pediatric Heart Transplantation: A Case Series and Review," Annals
of Pediatric Cardiology 9(1):42-45; Alsoufi, B., Deshpande, S.,
McCracken, C., Kogon, B., Vincent, R., Mahle, W., and Kanter, K.
2015. "Results of Heart Ttransplantation Following Failed Staged
Palliation of Hypoplastic Left Heart Syndrome and Related Single
Ventricle Anomalies," European Journal of Cardiothoracic Surgery
48(5):792-799, also cited below; Kanter, K. R., Mahle, W. T.,
Vincent, R. N., and Berg, A. M. 2011. "Aortic Complications after
Pediatric Cardiac Transplantation in Patients with a Previous
Norwood Reconstruction," Seminars in Thoracic and Cardiovascular
Surgery. Pediatric Cardiac Surgery Annual 14(1):24-28; Simmonds,
J., Burch, M., Dawkins, H., and Tsang, V. 2008, Op cit.).
[0390] To the foregoing can be added the preference in every
instance for endoluminal over extraluminal stents, the deterrent
consisting of the need for a small incision and some relatively
minor dissection to proceed directly to the level along the ductus
to be treated. The added trauma to gain access is compensated for
by an outcome more reliable over the long term. When the lumen
contains no stent, in-stent restenosis, for example, is impossible,
this but one of numerous risks associated with the use of
guidewires and allowing a foreign object to remain in the lumen, as
will be delineated herein. For example, the presence of a stent in
the lumen jeopardizes the subsequent use of an atherectomy
rotablator which can jam and deform the stent so that it no longer
serves its purpose. Rotablator jamming is addressed below in
section VII2j(1) entitled Incorporation of Adscititious
Capabilities into Barrel-assemblies.
[0391] Blocked by the sternum, direct access to the right coronary
artery or branch thereof for placement of an extraluminal stent is
not through a more traumatic median sternotomy (midsternal
thoracotomy, "zipper" incision), but rather through a trephine
sternotomy with a low speed, high torque trephine drill under
saline irrigation, the plug returned to the opening upon withdrawal
and closing. Means for minimizing the risk of adverse events
sequelary to penetration of the sternum are available (see, for
example, Asakura, Y., Kinoshita, M., Kasuya, Y., Sakuma, S., and
Ozaki, M. 2017. "Ultrasound-guided Sternal Bone Marrow Aspiration,"
Blood Research 52(2):148-150; Friedlis, M. F. and Centeno, C. J.
2016. "Performing a Better Bone Marrow Aspiration," Physical
Medicine and Rehabilitation Clinics of North America
27(4):919-939).
[0392] Broadly, poor outcomes often eventuate with transluminal
procedures opted for purely on the basis of minimal invasiveness.
For a debilitated patient less able or unable to tolerate an open
procedure, less traumatic procedures are approariate. However, when
this is not the case, an open procedure more likely to finally end
the problem is to be preferred, some added trauma notwithstanding.
This applies to small arterial stents and aortic sent grafts as
addressed below. The misguided approach is clearly seen when
failure of the transluminal repair necessitates open repair later
anyway--when the patient has further deteriorated.
[0393] Adverse sequelae to surgical breech of the sternum, such as
pericardial tamponade, are rare and have established remedies (see,
for example, Golota, J. J., Orlowski, T., Iwanowicz, K., Snarska,
J. 2016. "Air Tamponade of the Heart," Kardiochirurgia i
Torakochirurgia Polska [Polish Journal of Cardiothoracic Surgery]
13(2):150-153; Santavy, P., Troubil, M., and Lonsky, V. 2013.
"Pericardial Tamponade: A Rare Complication of Sternal Bone Marrow
Biopsy," Hematology Reports 5(3):e13; Inoue, H., Nakasato, T.,
Yamauchi, K., Nakamura, Y., Oshida, S., and Ehara, S. 2010. "Risk
Factors Concerning Sternal Bone Marrow Aspiration and Patient
Safety in Japan," Internal Medicine (Tokyo, Japan)
49(12):1089-1095; Jarry, J., Lang-Lazdunski, L., Perez, J. P.,
Barthelemy, R., Berets, O., and Jancovici, R. 2004. "A Serious
Complication of Sternal Puncture: Ppenetrating Injury of the
Ascending Thoracic Aorta," in French with Engish abstract at
Pubmed, Presse Medicale 33(1):22-24).
[0394] Relative efficacy as between minimally invasive transluminal
procedures and surgical intervention is not static but subject to
new developments, is gradually shifting in favor of more
conservative transluminal approaches over time. For example,
carotid endarterectomy, which may be untenably risky with severely
impaired patients posing a significant surgical risk, has been
found to result in better outcomes than does carotid artery
stenting, which is better tolerated, and coronary artery bypass
grafting has historically provided better outcomes than does
balloon angioplasty. This is, however, gradually changing with the
advent of improved medical management and apparatus such as drug
eluting stents and cerebral embolic protective devices, addressed
below in several sections but especially in section 4d(2) entitled
Ductus Wall Tumefacients, and flow reversal, addressed below in
section X2b entitled Stereotactic Resituation of a Mispositioned
Miniball.
[0395] The prepositioning of impasse-jackets described herein and
ductus side-entry jackets as described in copending application
Ser. No. 14/121,365 published as 20160051806, on pedicles or stumps
in organ transplantation allows the targeted delivery of graft
sustaining antigenotherapy and if necessary, immunosuppressive
drugs, and thus significant reduction if not elimination in the
systemic dose of potentially harmful immunosuppressive drugs such
as aclizumab, basiliximab, eculizumab, daclizumab, infliximab,
alemtuzumab, and other immunosuppressives which reduce patient
resisance to infectious disease (see, for example, Shao, M., Tian,
T., Zhu, X., Ming, Y., Iwakiri, Y., Ye, S., and Ye, Q. 2017.
"Comparative Efficacy and Safety of Antibody Induction Therapy for
the Treatment of Kidney: A Network Meta-analysis," Oncotarget
8(39):66426-66437; Zheng, J. and Song, W. 2017. "Alemtuzumab Versus
Antithymocyte Globulin Induction Therapies in Kidney
Transplantation Patients: A Systematic Review and Meta-analysis of
Randomized Controlled Trials," Medicine (Baltimore, Md.)
96(28):e7151; Hill, P., Cross, N. B., Barnett, A. N., Palmer, S.
C., and Webster, A. C. 2017. "Polyclonal and Monoclonal Antibodies
for Induction Therapy in Kidney Transplant Recipients," Cochrane
Database of Systematic Reviews 1:CD004759; Haynes, R., Harden, P.,
Judge, P., Blackwell, L., Emberson, J., Landray, M. J., Baigent,
C., Friend, P. J., and 154 collaborators 2014. "Alemtuzumab-based
Induction Treatment Versus Basiliximab-based Induction Treatment in
Kidney Transplantation (the 3C [Campath, Calcineurin Inhibitor
Reduction and Chronic Allograft Nephropathy] Study): A Randomised
Trial," Lancet 384(9955):1684-1690; Vazquez, J. A., Miceli, M. H.,
and Alangaden, G. 2013. "Invasive Fungal Infections in Transplant
Recipients," Therapeutic Advances in Infectious Disease
1(3):85-105; Hanaway, M. J., Woodle, E. S., Mulgaonkar, S., Peddi,
V. R., Kaufman, D. B., First, M. R., Croy, R., and Holman, J. 2011.
"Alemtuzumab Induction in Renal Transplantation," New England
Journal of Medicine 364(20):1909-1919; Safdar, N., Smith, J.,
Knasinski, V, Sherkow, C., Herrforth, C., Knechtle, S., and Andes,
D. 2010. "Infections After the Use of Alemtuzumab in Solid Organ
Transplant Recipients: A Comparative Study," Diagnostic
Microbiology and Infectious Disease 66(1):7-15) with an antibiotic
or antiviral when indicated, such as when the donor is
cytomegalovirus-seropositive and the recipient
cytomegalovirus-seronegative, azathioprine, basiliximab,
cyclosphosphamide, cyclosporine, tacrolimus, everolimus, sirolimus,
steroids, and so on, or radionuclides with or without an inherent
affinity for the organ, to only the transplanted organ without
suppression of the immune system for other disease, eliminates the
need for separate incisional access.
[0396] Generally, even though the directly targeted dose can be
more highly concentrated than if dispersed through the general
circulation, any fraction not taken up within the treatment site or
nidus will quickly become so diluted within the bloodstream as not
to pose the prospect of injury to upsteam tissue. If this is not
so, as when the drug is radioactive, the drug is delivered in
magnetically susceptible form so that the residue is stopped from
furher travel downstream by forcible detention, either against the
endothelium or urothelium. If the passing blood is not
significantly irradiated, the downstream ductus side-entry
impasse-jacket includes a permanent magnet sub-shell layer
magnetized perpendicular to the bloodstream to hold the drug
against the endothelium.
[0397] When drug delivery is directly pipe or feedline-targeted to
the nidus or lesion, medication that is radioactive or otherwise
potentially harmful introduced through the pipe or feedline in a
ferrofluid bypasses the upstream circulation and the tissue it
supplies. If radioactive, the feedline, as shown in copending
applications Ser. No. 14/121,365, FIGS. 5, 6, and Ser. No.
14/998,495 FIGS. 10A and 10B is shielded. If administration of the
drug is to continue over a long term, a small port at the body
surface is used as the drug entry point. If uptake at the lesion is
not complete and a radioactive residue is not to continue past the
drug delivery target, the residue is curtailed from continuation
through the bloodstream by a sub-shell electromagnet layer in the
side-entry jacket, piped impasse-jacket, or nonjacketing side-entry
connector to project an attractive field perpendicular or normal to
the long central axis of the substrate vessel.
[0398] The field strength of the electromagnet layer is set to no
greater than is necessary to draw the drug into the intima or
equivalent layer. If the drug is not harmful to normal tissue and
is to be drawn against rather than through the endothelium or
urothelium, for example, an impasse-jacket with permanent magnet
layer as shown in FIGS. 16A, 16B, and 16C and described below in
sections 12 and I15 is used. If harmful to normal tissue aside from
the target lesion, the magnetically carried residue can be
extracted through the grid of the impasse-jacket into the
perivascular far or equivalent tissue with the aid of a powerful
external (extracorporeal) tractive electromagnet.
[0399] A nonradioactive but potentially harmful residue is
neutralized through the release through a downstream ductus
side-entry jacket of a reversal agent. If delivery is automatic by
a microprocessor as addressed below in sections XX and XXI, then
the delivery of both the drug and the reversal agent or antidote is
automated. If not, then the residue is manuially introduced
immediately after the drug. If no reversal agent is available,
further passage through the bloodstream is prevented by introducing
the drug as magnetically carried for recovery by a downstream
impasse-jacket. Nanoparticulate drugs can be indissolubly or
dissolubly encapsulated to prevent or detain dissolution.
[0400] Because drugs are directly pipe-targeted to the treatment
site, were the the donor cytomegalovirus-seropositive and the
recipient cytomegalovirus-seronegative, for example, then provided
the efficacy of such treatment had been established, antivirals and
immunosuppressive drugs such as azathioprine, basiliximab,
cyclosphosphamide, cyclosporine, everolimus, tacrolimus, sirolimus,
methotrexate, steroids, and/or radionuclides with or without an
inherent affinity for the organ, can be targeted to the graft
without injury to other tissue or impairment to the immune system
as would expose the patient to pathogens.
[0401] Means for the automatic delivery of antimicrobial and
rejection-counteractive substances to sustain a transplant on a
continuous basis and alleviate dependency upon potentially toxic
systemic doses of immunosuppressive drugs are described in
copending application Ser. No. 14/121,365 published as 20160051806,
entitled Ductus Side-entry Jackets and Prosthetic Disorder Response
Systems, which describes a belt-supported power, control, and
pump/reservoir pack that delivers drugs through a small port at the
body surface, and application Ser. No. 14/998,495 published as
20170197028 entitled Nonjacketing Side-entry Connectors and
Prosthetic Disorder Response Systems, which describes the
implantation of these components with transdermal energy transfer
for closed body ambulatory operation and telemetric data transfer
to the clinic.
[0402] Such communication can transmit both command and diagnostic
signals (see, for example, Mirbozorgi, S. A., Bahrami, H., Sawan,
M., Rusch, L. A., and Gosselin, B. 2016. "A Single-Chip Full-duplex
High Speed Transceiver for Multi-site Stimulating and Recording
Neural Implants," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Circuits and Systems 10(3):643-653;
Hannan, M A., Abbas, S. M., Samad, S. A., and Hussain, A. 2012.
"Modulation Techniques for Biomedical Implanted Devices and Their
Challenges," Sensors (Basel, Switzerland) 12(1):297-319). While a
centralized computer to administer patient-specific prescription
programs would eliminate the need for a microcontroller implant in
each patient or included in a carried power and control pack,
current telemetric communication between the centralized controller
and each patient falls far short of the dependability required in
such an arrangement.
[0403] The same may be said for transdermal or transcutaneous
charging of the implanted or carried battery, distance
considerations for the transmission of power thus currently
limiting charging to an at-home or clinic function. Eventually,
large regions may be administered by centralized computers. The
current state of the medical data telemetric and transcutaneous
charging capabilities is addressed below in the section entitled
Exemplary Channel of Control in a Fully Implanted Ambulatory
Adaptive Hierarchical Control System for Automatic Response to a
Comorbid Condition.
[0404] Ductus side-entry jackets and nonjacketing side-entry
connectors are adaptations of the jackets or collars described
herein, to allow the direct piping of drugs, metabolites, enzymes,
hormones, temperature sensor/heating or cooling devices, and
miniature cabled devices, such as lasers, electrostimulatory, or
neuromodulatory, electrodes, intravascular ultrasound viewing, or
high-intensity focused ultrasound, or ultrasonic histotripsy,
ablation, probes to be fully implanted and stably positioned over
an indefinitely long period. Piping is addressed below in section
I15e entitled Direct Lines from the Body Surface to and from
Impasse- and Other Type Jackets. An exemplary automatic disorder
response system is addressed in section XX below and FIG. 107, with
the control of such an implanted arrangement addressed in section
XXI and FIG. 108.
[0405] Using magnetic force to restrict delivery of graft antigens,
counteractive antibodies and immunosuppressive medication to and
concentrate these in a targeted segment or organ, for example,
leaves the rest of the body substantially immunocompetent, reducing
the risk of transplant infection with an
immunosuppression-opportunistic cytomegalovirus, Epstein-Barr
virus, which poses the threat of post transplantation
lymphoproliferative disease that can lead to non-Hodgkin's lymphoma
and death (see, for example, Martinez, O. M. and Krams, S. M. 2017.
"The Immune Response to Epstein Barr Virus and Implications for
Posttransplant Lymphoproliferative Disorder," Transplantation
101(9):2009-2016; Bishnoi, R., Bajwa, R., Franke, A. J., Skelton,
W. P. 4th, Wang, Y., and 4 others 2017. "Post-transplant
Lymphoproliferative Disorder (PTLD): Single Institutional
Experience of 141 Patients," Experimental Hematology and Oncology
6:26; Das, B., Morrow, R., Huang, R., and Fixler, D. 2016.
"Persistent Epstein-Barr Viral Load in Epstein-Barr Viral Naive
Pediatric Heart Transplant Recipients: Risk of Late-onset
Post-transplant Lymphoproliferative Disease," World Journal of
Transplantation 6(4):729-735; "Dharnidharka, V. R., Webster, A. C.,
Martinez, O. M., Preiksaitis, J. K., Leblond, V. 5., and Choquet,
S. 2016. "Post-transplant Lymphoproliferative Disorders," Nature
Reviews. Disease Primers 2:15088; Jha, H. C., Pei, Y., and
Robertson, E. S. 2016. "Epstein-Barr Virus: Diseases Linked to
Infection and Transformation," Frontiers in Microbiology 7:1602;
Lynch, J. P. 3rd, Sayah, D. M., Belperio, J. A., and Weigt, S. S.
2015 "Lung Transplantation for Cystic Fibrosis: Results,
Indications, Complications, and Controversies," Seminars in
Respiratory and Critical Care Medicine 36(2):299-320; San-Juan, R.,
Manuel, O., Hirsch, H. H., Fernandez-Ruiz, M., Lopez-Medrano, F.,
and 4 others with 105 collaborators 2015. "Current Preventive
Strategies and Management of Epstein-Barr Virus-related
Post-transplant Lymphoproliferative Disease in Solid Organ
Transplantation in Europe. Results of the ESGICH [European Study
Group of Infections in Compromised Hosts] Questionnaire-based
Cross-sectional Survey," Clinical Microbiology and Infection
21(6):604.e1-9; San-Juan, R., Comoli, P., Caillard, S., Moulin, B.,
Hirsch, H. H., and Meylan, P. 2014. "Epstein-Barr Virus-related
Post-transplant Lymphoproliferative Disorder in Solid Organ
Transplant Recipients," Clinical Microbiology and Infection 20
Supplement 7:109-118; Green, M. and Michaels, M. G. 2013.
"Epstein-Barr Virus Infection and Posttransplant
Lymphoproliferative Disorder," American Journal of Transplantation
13 Supplement 3:41-54; Allen, U. D., Farkas, G., Hebert, D.,
Weitzman, S., Stephens, D., and 6 others 2005. "Risk Factors for
Post-transplant Lymphoproliferative Disorder in Pediatric Patients:
A Case-control Study," Pediatric Transplantation 9(4):450-455;
Allen, U., Alfieri, C., Preiksaitis, J., Humar, A., Moore, D., and
8 others 2002. "Epstein-Barr Virus Infection in Transplant
Recipients: Summary of a Workshop on Surveillance, Prevention, and
Treatment," Canadian Journal of Infectious Diseases 13(2):89-99;
Aris, R. M., Maia, D. M., Neuringer, I. P., Gott, K., Kiley, S.,
Gertis, K., and Handy, J. 1996. "Post-transplantation
Lymphoproliferative Disorder in the Epstein-Ban Virus-naive Lung
Transplant Recipient," American Journal of Respiratory and Critical
Care Medicine 154(6 Part 1):1712-1717).
[0406] Polyoma papovavirus, usually BK virus [from the initials of
a renal transplant patient]), or Polyomavirus hominis type 1
infection is another significant threat (see, for example,
Ambalathingal, G. R., Francis, R. S., Smyth, M. J. 2, Smith, C.,
and Khanna, R. 2017. "BK Polyomavirus: Clinical Aspects, Immune
Regulation, and Emerging Therapies," Clinical Microbiology Reviews
30(2):503-528; Abend, J. R., Changala, M., Sathe, A., Casey, F.,
Kistler, A., Chandran, S., Howard, A., and Wojciechowski, D. 2017.
"Correlation of BK Virus Neutralizing Serostatus with the Incidence
of BK Viremia in Kidney Transplant Recipients," Transplantation
101(6):1495-1505; Kable, K., Davies, C. D., O'connell, P. J.,
Chapman, J. R., and Nankivell, B. J. 2017. "Clearance of BK Virus
Nephropathy by Combination Antiviral Therapy with Intravenous
Immunoglobulin," Transplantation Direct 3(4):e142; Sharma, R.,
Tzetzo, S., Patel, S., Zachariah, M., Sharma, S., and Melendy, T.
2016. "BK Virus in Kidney Transplant: Current Concepts, Recent
Advances, and Future Directions," Experimental and Clinical
Transplantation 14(4):377-384; Jamboti, J. S. 2016. "BK Virus
Nephropathy in Renal Transplant Recipients," Nephrology (Carlton,
Victoria, Austrailia) 21(8):647-654; Vigil, D., Konstantinov, N.
K., Barry, M., Harford, A. M., Servilla, K. S., and 4 others 2016.
"BK Nephropathy in the Native Kidneys of Patients with Organ
Transplants: Clinical Spectrum of BK Infection," World Journal of
Transplantation 6(3):472-504; Umbro, I., Tinti, F., Muiesan, P.,
and Mitterhofer, A. P. 2016. "Different Behaviour of BK-virus
Infection in Liver Transplant Recipients," World Journal of
Gastroenterology 22(4):1532-1540; Huang, G., Wang, C. X., Zhang,
L., Fei, J. G., Deng, S. X., and 5 others 2015. "Monitoring of
Polyomavirus BK Replication and Impact of Preemptive
Immunosuppression Reduction in Renal-transplant Rrecipients in
China: A 5-year Single-center Analysis," Diagnostic Microbiology
and Infectious Disease 81(1):21-26; Pham, P. T., Schaenman, J., and
Pham, P. C. 2014. "BK Virus Infection Following Kidney
Transplantation: An Overview of Risk Factors, Screening Strategies,
and Therapeutic Interventions," Current Opinion in Organ
Transplantation 19(4):401-412; Huang, G., Zhang, L., Liang, X.,
Qiu, J., Deng, R., and 4 others 2014. "Risk Factors for BK Virus
Infection and BK Virus-associated Nephropathy Under the Impact of
Intensive Monitoring and Pre-emptive Immunosuppression Reduction,"
Transplantation Proceedings 46(10):3448-3454; Hirsch, H. H. and
Snydman, D. R. 2005. "BK Virus: Opportunity Makes a Pathogen,"
Clinical Infectious Diseases 41(3):354-360; Finberg, R. and
Fingeroth, J. 2005. "Infections in Transplant Recipients," Chapter
117 in Harrison's Principles of Internal Medicine, 16th Edition,
New York, N.Y.: McGraw-Hill, pages 781-789; Koukoulaki, M.,
Grispou, E., Pistolas, D., Balaska, K., Apostolou, T., and 7 others
2009. "Prospective Monitoring of BK Virus Replication in Renal
Transplant Recipients," Transplant Infectious Disease 11(1):1-10),
resulting in irremediable graft sloughing.
[0407] The Merck Manual of Diagnosis and Therapy, Edition 18,
Chapter 166, "Transplantation," page 1369 enumerates viral,
bacterial, fungal, and parasitic organisms found to infect
immunocompromised recipients. If necessary, the same or another
impasse-jacket at the arterial inlet is used to release a viricide.
Regardless of the projected time or times for release, the
impasse-jacket or jackets are fixed in position just after the
organ is removed and before completing the graft. Thereafter,
release using any of several mechanisms addressed in sections
herein on impasse-jackets can be preemptive, prophylactic, or
both.
[0408] Transplant harvesting preserves sufficient connections or
pedicles including major arteries and veins to allow the placement
of entry (inlet, inflow) and exit (outlet, outflow)
impasse-jackets, so that these are introduced having already been
applied to the target organ. A kidney, for example, is harvested
with its renal artery, renal vein, and ureter remaining attached.
Perigraft infection should it ensue can be treated using the same
impasse-jacket or jackets. When graft antigens, counteractive
antibodies, immunosuppressive, and antibiotic drugs, for example,
must be delivered to different ductus, Ommaya-type reservoirs,
subcutaneous infusion set cannulae with catheters leading to the
respective jackets, or similar access portals at the body surface
are spaced apart to reduce the chance for human error in
administering the medication.
[0409] Direct piping from the body surface, addressed below in the
sections entitled Direct Lines from the Body Surface to and from
Impasse- and Other Type Jackets and Single and Plural Circuit
Pumping through Direct Lines to Jackets makes it possible to
selectively target each impasse-jacket with the substance intended
by direct piping. Syringe refill cartridges or portable miniature
metering pumps connected to the access portals or infusion cannulae
at the body surface selectively supply the drug for each target
impasse-jacket. Access to intermittent segments along a ductus,
such as unresected skip lesions of Crohn's disease, or regional
enteritis, or with atherosclerotic plaques where remodeling
discourages transluminal treatment, the chronic condition warrants
the implantation of fluid feedlines with a small port at the body
surface.
[0410] Branching the feedline distal to the port opening allows the
use of a single opening in the port at the body surface. If
medication is to be administered automatically, then a controlling
microprocessor and associated components as appropriate and
delineated in sections XX and XXI below are implanted. When the
delivery line is branched, the microprocessor actuates the one
small flat drug reservoir pump to medicate the lesions at once.
Likewise to reserve port openings for other drugs in comorbidity,
when a given drug or other therapeutic substance would best be
delivered to separate points in a particular order, successive side
branches from a common line may be used, whether the takeoffs
follow in anterograde or retrograde order.
[0411] An unmagnetized inlet jacket directly piped to from a portal
at the body surface can deliver a drug and when necessary, an
outlet jacket similarly piped can deliver a reversal agent. Where
dosing would best respond quickly to changing physiological
criteria such as pulse rate or blood pressure, sensors placed to
transmit the pertinent data to the pump can be used to administer
the medication automatically. Direct line feed to impasse-jackets
and/or their outriggers or dummy collars from the body surface is
addressed below in the section of like title. Either or both
impasse-jackets and dummy collars can be directly supplied or lumen
contents drawn by a portable pump connected to an infusion set
cannula with catheter leading to the jacket or an Ommaya reservoir
type connector implanted at the body surface.
[0412] Single, dual, and multipump circuits are delineated below in
the section entitled Single and Plural Circuit Pumping through
Direct Lines to jackets. The jackets and/or other implants
described herein, to include patch-magnets, and magnet-wraps, and
bonding of the drug to the magnetic drug carrier then serve to
steer the medication into the lumen wall, the anastomosis, or
parenchyma. Broadly, impasse-jackets for later use are easily
prepositioned as a part of any open procedure where an eventual
need for drug targeting is probable--essentially, always. When the
initial medication requires only an entry jacket but the
prospective need for another drug that would generate a residue
requiring reversal or neutralization is present, an exit jacket is
prepositioned without being charged, or loaded with the reversal
agent.
[0413] Magnetic drug-targeting implants applied to the ileum and
colon, for example, make it possible to direct corticosteroids,
immunomodulators, antiinfectives, gene therapy vehicles, vaccines,
antineoplastic drugs, enzymes, cytokines, whether as `smart pills,`
for example, to only those segments affected by regional enteritis
most often seen as ileocolitis or Crohn's disease, in high
concentration with minimal delivery to the rest of the body. When
tight control over distribution is not critical, passive
apportionment among a number of jackets is sometimes possible at
less risk and expense; however, when it is essential, more extended
coverage is achieved by direct line delivery to any or all of a
plurality of impasse-jackets. The strength of magnetization or
degree of tractive force from collar to collar is increased in the
Proximodistal, or antegrade, direction.
[0414] Particles with a greater mass of ferromagnetic or
susceptible content will generally decrease from jacket to jacket.
When the particles are equally susceptible, the distribution
results from chance proximity to each pole traversed. Provided care
is given to avoiding interactions between different ductus treated
thus and recurving of the same ductus, this allows a range of
tractive force over the distance covered by the array or arrays at
different levels along the ductus. While the contingency of
drug-carrier particle proximity to each collar along the gut
requires that the apportionment of the drug among the collars
deviate from the ideally uniform or aliquot, the statistical
apportionment among collars of the array gradient is sufficient to
treat each segment affected. Once placed, the jackets are
prepositioned for followup dosage at any later time.
[0415] Ending the array with a jacket, an exit-jacket, that
releases a reversal agent allows drugs so highly toxic that even a
residue in the bloodstream can prove problematic, notably those
chemotherapeutic, to be restricted to the target segment with an
exit impasse-jacket or exit jacket to release a reversal agent to
eliminate any residue when a recommended precaution. Similarly,
placing a drug trapping and releasing impasse-jacket at the inlet
to an organ and an exit jacket at the outlet allows the selective
targeting of that organ. Whether impasse-jackets, addressed below
in the sections entitled Concept of the Impasse-jacket, Miniball
and Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets, and Cooperative Use of Impasse-jackets in Pairs
and Gradient Arrays, or stent-jackets, addressed below in the
section entitled Stent-jackets and Stent-jacket Supportng Elements,
a collar side-slot accommodates a running attachment of connective
tissue, for example.
[0416] When it is realized that many ailments can be treated
through the differential delivery of drugs to ductus such as blood
vessels as these enter and depart a target organ, a lesioned
segment, or different segments of a lumen, the potential
significance of such means becomes clear. When the medication is
encapsulated in the form of microspheres or miniballs, it is also
possible with the aid of an external electromagnet to extract these
should some mishap occur or some unforeseen eventuality arise. The
term `barrel-assembly` used to denote a catheteric extension to the
barrel of a specially adapted, or interventional, airgun and
`muzzle-head`or `muzzle-probe,` its distal terminus, when the
medication is in the form of a ferrofluid, recovery is by means of
an endoscope with a magnetized tip or the recovery tractive
electromagnets in the muzzle-head of a barrel-assembly, as will be
described.
[0417] Although treatment is targeted at a certain organ or
segment, associated symptoms, however remote, induced by the
primary pathology, that is, secondary or sequelary, derived from
those primary, rather than parallel or pleiotropic, are inhibited
from spreading as well. With respect to the Crohn's example, the
disease appears to involve an abnormal immune response of
multifactorial genetic basis to the normal flora occupying the gut,
so that associated symptoms, to include those concomitant or
antecedent, however remote, would appear to be co-original.
[0418] Bowel disorders briefly addressed below, extraintestinal
symptoms, more frequent with perianal Crohn's disease (see, for
example, Mahmoud, N. N., Halwani, Y., Montbrun, S., Shah, P. M.,
Hedrick, T. L. and 8 others 2017. "Current Management of Perianal
Crohn's Disease," Current Problems in Surgery 54(5):262-298; Klag,
T., Goetz, M., Stange, E. F., and Wehkamp, J. 2015. "Medical
Therapy of Perianal Crohn's Disease," Viszeralmedizin (Visceral
Medicine) 31(4):265-272; Freidman, S. and Blumberg, R. S. 2005.
"Inflammatory Bowel Disease," "in Harrison's Principles of Internal
Medicine, 16th Edition, New York, N.Y.: McGraw-Hill, page 1783;
Galandiuk, S., Kimberling, J., Al-Mishlab, T. G., and Stromberg, A.
J. 2005. "Perianal Crohn Disease: Predictors of Need for Permanent
Diversion," Annals of Surgery 241(5):796-802), include those
ocular, arthritic, hepatic, hematologic, and cobalamin (vitamin
B.sub.12) deficiency (Babior, B. M. and Bunn, H. F. 2005.
"Megaloblastic Anemias," in Harrison's op cit., Page 604), posing a
risk for atrophic gastritis, and if not corrected, gastric
adenocarcinoma, magaloblastic anemia, achlorhydria predisposing to
salmonellosis, and neurologic dysfunction, among others (see, for
example, Del Valle, J. 2005. "Peptic Ulcer Disease and Related
Disorders," in Harrison's op cit., Page 1761; The Merck Manual of
Diagnosis and Therapy, 18th Edition, 2006, Section 2,
Gastrointestinal Disorders, Subsection 18, "Inflammatory Bowel
Disease," page 149 and Section 14, Infectious Diseases, Subsection
167, "Biology of Infectious Diseases," page 1387).
[0419] Extraintestinal symptoms appearing before frank ileocolitis
should prompt consideration of placing collars to preemptively
inhibit spread of the disease to the mesentery, for example. Such
implants also allow the controlled and targeted release and
suppression of released drugs or other substances from outside the
body. Different layers or concentric shells of drugs in miniball or
microsphere implants as well as those applied as coatings to other
type implants such as absorbable stent-jackets and magnet-wraps, to
be described herein can be released by:
[0420] 1. Spontaneous dissolution at body temperature, accelerated
by the blood washing over the implant when suspended in the
bloodstream.
[0421] 2. Exposing the layer to another agent whether released from
a second such implant whether by the same or different means, such
as infused, injected, or ingested, that induces the dissolution of
the layer.
[0422] 3. With the use of an alternating magnetic or
electromagnetic field, induction heating each successive
magnetically susceptible nanoparticle-bound drug or radioisotope
carrier-incorporating layer to its respective temperature of
dissolution
[0423] 4. When the implant is sufficiently stable in position,
using a constant magnetic field to break up each layer. 5.
Providing each layer or shell with a proportionally distinct mass
of magnetically susceptible matter to allow that layer to be
disintegrated through a combination of heating, traction, and/or
exposure to another chemical in any combination.
[0424] Stent- and impasse-jackets provide such a constant magnetic
field and allow endoluminally implanted drugs to be aligned to
lesions. If placed near to the body surface, noninjurious heating
can be accomplished by means of an aquathermia pad, hot air gun, or
hand held blow dryer. In addition to thermoelectric heat induction
by placement in a radiofrequency alternating magnetic field, the
dissolution of more deeply placed biodegradable (absorbable)
implants with or without the release of therapeutic substances,
such as those encapsulated or entrapped within a polyanhydride, can
be effected with conventional electromagnetic eddy current
induction heating (see, for example, Hartshorn, L. 1949.
Radio-frequency Heating, London, England: Allen and Unwin).
[0425] Since ductus-intramural implants incorporate sufficient
ferrous content to allow their magnetic relocation or extraction at
any moment if necessary, the ferrous content is usually sufficient
for heat induction as well. The potential applications for the
heating of implants are numerous and will be specified. Where
arrestability and recoverability of a miniball that enters the
circulation are satisfied by the incorporation of sufficient
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder, induction more effective with larger grains. Powder
and grains both present sufficient surface area for quick
absorption at a subtoxic level. The formulation of
ductus-intramural implants and miniballs in particular, is
addressed below in the section entitled Noninvasive Dissolution on
Demand of Absorbable Stent-jackets, Base-tubes, Radiation Shields,
and Miniballs.
[0426] With release controllable from outside the body, the layers
can represent doses of the same drug, or a drug, chemical, or
enzyme, for example, released to supplement or counteract one
released earlier. Sequential release from the same implant, such as
a ductus-intramurally implanted stay or miniball or a lumen
suspended miniball can then be coordinated between and among any
such implants. Different implants can be controlled in a
coordinated and timed manner to release chemicals that combine to
form a therapeutic compound or mixture or which act
synergistically. Such capability is expected to prompt the
development of magnetically susceptible nanoparticle bound drugs
specially formulated for such delivery. Situating magnetized
miniballs, stays, arrays thereof, or jackets along a section of a
ductus allows targeting a drug or drugs to that segment for
controlled uptake from outside the body with or without such timed
and coordinated release.
[0427] Once the blood-borne overload passing through the liver
reaches a threshold, the significance of iron as a carcinogen is
established; however, here thr blood concentration of iron cannot
rise to the level of toxicity, even when the tiny miniballs or
stays are not encapsulated within a polymeric outer jacket or
shell; using the methods described herein should not release an
absolute amount of iron into the bloodstream as would even rise to
the level of medical significance. Much pertinent research is open
to question in any event (see, for example, Deugnier, Y. and
Loreal, O. 2000. "Iron as a Carcinogen," Chapter 22, pages 239-249
in Barton, J. C. and Edwards, C. Q. (eds.), Hemochromatosis:
Genetics, Pathophysiology, Diagnosis and Treatment, Cambridge,
England: Cambridge University Press. When containing radioisotopes,
an absorbable radiation shield-jacket with dissolution time keyed
to the half-life of the radioisotope is used, as addressed below in
the section entitled Radiation Shield-jackets and Radiation
Shielded Stent-jackets Absorbable and Nonabsorbable.
[0428] Due to dilution, any conventional drug that is highly
concentrated for the lesioned segment that may continue in the
circulation will be innocuous. Reciprocally, dependency upon
circulation of the drug eliminated, first pass or presystemic
metabolic reduction is avoided so that its concentration or dose
can be keyed to that optimal for direct delivery to the lesion
without a need to reduce the level to avoid adverse side effects
risked when it is circulated. When available, unconventional drugs
that despite dilution would be toxic are neutralized by the release
from a segment exit or outlet jacket of a reversal or neutralizing
agent, as addressed below in the section entitled Cooperative Use
of Impasse-jackets in Pairs and Higher Combinations, among others
allows a concentraton of the drug in the lesion.
[0429] For toxic antineoplastic drugs, release is initiated at the
start of the segment or inlet of the organ to be treated. Provided
a counteractant is available, any residue can be neutralized by a
counteractant released from an exit jacket at the end of the
segment or outlet of the organ. Targeted chemotherapy through the
application of magnetic force, with or without surgery or radiation
to treat localized (nondisseminated, nonmetastazized,
nonmetastatic) as opposed to a systemic disease thus averts the
need to moderate the dose, instead allowing the drug to be
administered at the optimal concentration for the lesion in
virtually any patient regardless of performance status. Whether
given as neoadjuvant, or before surgery to enhance resectability
and/or preserve local organ function (Merck Manual of Diagnosis and
Therapy, 18th edition, page 1167), or additionally administered as
a precaution, only the backup or adjuvant chemotherapeutic level of
the drug circulated requires the application of toxicity-averting
dose-interval strategy that currently dominates the use of such
drugs.
[0430] Equally important, the elimination or substantial
elimination of a drug from the bloodstream also avoids the liver
and eliminates drug-drug interactions, not only allowing
concomitant treatment of a systemic comorbidity with a drug that
must be circulated, but keeping the bloodstream free of a drug that
would later become a deterrent to the use of another drug to treat
an unforeseeable intercurrent systemic disease. Drug-drug
interactions are then limited to the targeted lesion. The use of
drug miniballs, stays, and impasse-jackets to treat a local area by
direct breakdown, elution, or attracting a magnetized carrier-bound
drug from the passing blood, and impasse-jackets in pairs, for
example, to mark off a segment of a ductus or an entire organ is
not intended to affect liver metabolism or the systemic serum level
of a constituent or constituents known harmful for the diseased
area defined thus, but rather to block the transport of these
harmful substances across cell membranes at the locus, segment, or
organ.
[0431] The apparatuses described herein are determined in size by
the diameter of the lumen to be treated and ultimately limited in
this regard by the degree of miniaturization that can be achieved.
While implantation within the walls of lumina is specifically
addressed, limitation to such use and not to other organs is not to
be imputed. Embodiments for use in the trachea, bronchi, or
gastrointestinal tract, which are relatively large, can incorporate
components which for use in smaller blood vessels and ureters, for
example, will demand greater miniaturization over time. Such
components include plural implant discharge channels, or
barrel-tubes, to allow the delivery of multiple implants per
discharge, and a central passageway to accommodate a commercial
cabled device, such as an endoscope, laser, or rotational tool.
Where possible, control electronics that can compensate for
components too large to fit inside the endoluminal portion of the
apparatus are relegated to an extracorporeal power and control
housing.
[0432] An example is the use of an embedded mixed-signal
microcontroller to regulate the temperature of heating elements
using the equivalent direct electrical current, thus eliminating
the need to position temperature feedback sensors inside the
catheteric member. Suitable microcontrollers are produced by
Microchip Technology, Atmel, Freescale Semiconductor, and Texas
Instruments corporations, for example. Remote control by a
centralized computer and charging of the implanted battery by
distributed charging stations is briefly addressed above in this
section and below in the section entitled Exemplary Channel of
Control in a Fully Implanted Ambulatory Adaptive Hierarchical
Control System for Automatic Response to a Comorbid Condition.
[0433] The applicability of the system described herein to ductus
with weak, disease-weakened or malacotic walls, such as of veins
and atheromatous arteries, wherewith remodeling has atrophied the
media (see, for example, Glagov, S., Weisenberg, E., Zarins, C. K.,
Stankunacius, R., and Kolettis, G. J. 1987. "Compensatory
Enlargement of Human Atherosclerotic Coronary Arteries," New
England Journal of Medicine 316(22):1371-1375), and the tunica
adventitia (tunica externa) appears too weak to compensate
(Haurani, M. J. and Pagano, P. J. 2007. "Adventitial Fibroblast
Reactive Oxygen Species as Autacrine and Paracrine Mediators of
Remodeling: Bellwether for Vascular Disease?," Cardiovascular
Research 75(4):679-689), for example, is extended by the capability
to include a suitable thickness of tissue surrounding the
ductus.
[0434] Calcification introduces a factor of unpredictability that
requires testing of the vessel or other ductus wall strength as
addressed below in section XVII entiled Testing and Tests (see also
Kolossvary, M., Szilveszter, B., Merkely, B., and Maurovich-Horvat,
P. 2017. "Plaque Imaging with CT--A Comprehensive Review on
Coronary CT Angiography Based Risk Assessment," Cardiovascular
Diagnosis and Therapy 7(5):489-506; Obaid, D. R., Calvert, P. A.,
Gopalan, D., Parker, R. A., Hoole, S. P., and 4 others 2013.
"Atherosclerotic Plaque Composition and Cclassification Identified
by Coronary Computed Tomography: Assessment of Computed
Tomography-generated Plaque Maps Compared with Virtual Histology
Intravascular Ultrasound and Histology," Circulation.
Cardiovascular Imaging 6(5):655-664; Matsuo, Y., Takumi, T.,
Mathew, V., Chung, W. Y., Barsness, G. W., and 8 others 2012.
"Plaque Characteristics and Arterial Remodeling in Coronary and
Peripheral Arterial Systems," Atherosclerosis 223(2):365-371). If
necessary, some thickness of the tissue surrounding the ductus can
be hardened, or sclerosed, and made strongly adherent to the
adventitia by microinjection with a tissue adhesive-hardener or
binder-fixative effectively increasing the thickness and
strengthening the wall. The least effective magnetic force used,
this will often allow the lumen wall to accommodate and retain
magnetically retracted ductus-intramural implants without
delamination, or the separation or avulsion of the tunics or tissue
layers of the ductus, here veins.
[0435] Tissue which surrounds and participates in the physiology of
the ductus as to support normal function as addressed below in the
section entitled Accommodation of the Adventitial Vasculature,
Innervation, and Perivascular Fat, is usually not to be treated
thus; however, perivascular fat that is responsible for endothelial
dysfunction is best included in the hardened tissue thus adding
thickness and reducing the adverse effect at the same time (see,
for example, Kennedy, S. and Salt, I. P. 2017. "Molecular
Mechanisms Regulating Perivascular Adipose Tissue--Potential
Pharmacological Targets?," British Journal of Pharmacology
174(20):3385-3387; Zaborska, K. E., Wareing, M., and Austin, C.
2017. "Comparisons Between Perivascular Adipose Tissue and the
Endothelium in Their Modulation of Vascular Tone," British Journal
of Pharmacology 174(20):3388-3397; Akoumianakis, I., Tarun, A., and
Antoniades, C. 2017. "Perivascular Adipose Tissue as a Regulator of
Vascular Disease Pathogenesis: Identifying Novel Therapeutic
Targets," British Journal of Pharmacology 174(20):3411-3424;
Ayala-Lopez, N. and Watts, S. W. 2017. "New Actions of An Old
Friend: Perivascular Adipose Tissue's Adrenergic Mechanisms,"
British Journal of Pharmacology 174(20):3454-3465; Nosalski, R. and
Guzik, T. J. 2017. "Perivascular Adipose Tissue Inflammation in
Vascular Disease," British Journal of Pharmacology
174(20):3496-3513; Srikakulapu, P., Upadhye, A., Rosenfeld, S. M.,
Marshall, M. A., McSkimming, C., and 6 others 2017. "Perivascular
Adipose Tissue Harbors Atheroprotective IgM-Producing B Cells,"
Frontiers in Physiology 8:719; Horimatsu, T., Kim, H. W., and
Weintraub, N. L. 2017. "The Role of Perivascular Adipose Tissue in
Non-atherosclerotic Vascular Disease," Frontiers in Physiology
8:969; Ramirez, J. G., O'Malley, E. J., and Ho, W. S. V. 2017.
"Pro-contractile Effects of Perivascular Fat in Health and
Disease," British Journal of Pharmacology 174(20):3482-3495; Li,
C., Wang, Z., Wang, C., Ma, Q., and Zhao, Y. 2015. "Perivascular
Adipose Tissue-derived Adiponectin inhibits Collar-induced Carotid
Atherosclerosis by Promoting Macrophage Autophagy," Public Library
of Science One 10(5):e0124031; Villacorta, L. and Chang, L. 2015.
"The Role of Perivascular Adipose Tissue in Vasoconstriction,
Arterial Stiffness, and Aneurysm," Hormone Molecular Biology and
Clinical Investigation 21(2):137-147; Manka, D., Chatterjee, T. K.,
Stoll, L. L., Basford, J. E., Konaniah, E S , and 6 others 2014.
"Transplanted Perivascular Adipose Tissue Accelerates
Injury-induced Neointimal Hyperplasia: Role of Monocyte
Chemoattractant Protein-1," Arteriosclerosis, Thrombosis, and
Vascular Biology 34(8):1723-1730; Payne, G. A. 2010. Contribution
of Perivascular Adipose Tissue to Coronary Vascular Dysfunction,
Dissertation, Indiana University; Payne, G. A., Bohlen, H. G.,
Dincer, U. D., Borbouse, L., and Tune, J. D. 2009. "Periadventitial
Adipose Tissue Impairs Coronary Endothelial Function via
PKC-beta-dependent Phosphorylation of Nitric Oxide Synthase,"
American Journal of Physiology. Heart and Circulatory Physiology
297(1):H460-H465; Payne, G. A., Borbouse, L., Bratz, I. N., Roell,
W. C., Bohlen, H. G., Dick, G. M., and Tune, J. D. 2008.
"Endogenous Adipose-derived Factors Diminish Coronary Endothelial
Function via Inhibition of Nitric Oxide Synthase," Microcirculation
15(5):417-426; Dick, G. M., Katz, P. S., Farias, M. 3rd, Morris,
M., James, J., Knudson, J. D., and Tune, J. D. 2006. "Resistin
Impairs Endothelium-dependent Dilation to Bradykinin, but Not
Acetylcholine, in the Coronary Circulation," American Journal of
Physiology. Heart and Circulatory Physiology
291(6):H2997-H3002).
[0436] A small or miniature spine and ribs type stent-jacket,
described below in the section entitled Spine and Ribs-type
Stent-jacket, is used to avoid any blood vessels or nerves. The
fast initial setting and curing times of long chain cyanoacrylate
cements allows the incorporation into stay insertion tools of an
applicator to coat each stay with cement on ejection. Testing
methods to assist in determining whether preparatory remedial
measures are necessary to stent an artery weakened by disease, for
example, are delineated below in the section entitled Testing and
Tests.
[0437] In instances where arterial shrinkage and enlargement
produce irregularity in the luminal diameter or radial symmetry of
the luminal wall (see, for example, de Groot, P. and Veldhuizen, R.
W. 2006. "Human Coronary Artery Remodeling, Beginning and End of
the Atherosclerotic Process," Public Library of Science One 1:e91;
Smits, P. C., Bos, L. Quarles van Ufford, M. A., Eefting, F. D.,
Pasterkamp, G., and Borsta, C. 1998. "Shrinkage of Human Coronary
Arteries is an Important Determinant of de Novo Atherosclerotic
Luminal Stenosis: An in Vivo Intraductal Ultrasound Study," Heart
79(2):143-147; Prati, F., Mallus, M. T., Parma, A., Lioy, E.,
Pagano, A., and Boccanelli, A.1998. "Incidence of Compensatory
Enlargement and Paradoxical Shrinkage of Coronary Arteries in
Presence of Atherosclerotic Lesions: An Intracoronary Ultrasound
Study Based on Multiple Cross-section Analysis Per Artery,"
Giornale Italiano di Cardiologia 28(10):1063-1071; Birnbaum, Y.,
Fishbein, M. C., Luo, H., Nishioka, T., and Siegel, R. J. 1997.
"Regional Remodeling of Atherosclerotic Arteries: A Major
Determinant of Clinical Manifestations of Disease," Journal of the
American College of Cardiology 30(5):1149-1164), an extraluminal
stent with foam lining and spring hinge enabled expandability can
maintain patency with less trauma and disruption to normal
physiology than can an endoluminal stent.
[0438] To accommodate a tapered segment along a ductus and its
lumen, an endoluminal or intravascular stent may flex to some
extent, but the margins and body must exert sufficient outward
force to prevent migration. If to complement the lumen, the ends
were made unequal in diameter, the sides would incline between the
two diameters; by contrast, extraluminal stent-jackets can adjust
for variation in the diameter of the substrate ductus the jacket
encircles by altering the strength of ,mgnetization along the
length of the jacket, which is uniform in diameter from end to
end.
[0439] That is, while ordinarily made to standard dimensions and
field strengths rather than customized, extraluminal stent-jackets
conform to all but the most pronounced changes in diameter of the
substrate ductus due to the compliance of the foam lining, and past
that degree of change in diameter, itself unlikely, the jacket can
be differentially magnetized from one segment to another along the
jacket length without affecting stent diameter. An extraluminal
stent does not have margins unlike or less flexible than
intervening segments and can be adjusted in strength of
magnetization in any segment. The ductus-intramural implants for
insertion in the arterial tree contain sufficient ferrous content
to assure retrieval by prepositioned means. Such implants can
incorporate medication, non-drug therapeutic substances, a
radiation emitting seed, or protein solder, for example, in any
combination.
[0440] When not specifically encapsulated to prevent dissolution,
iron-containing absorbable implants described herein will leave an
iron residue too small to produce iron overload. When the sum
quantity of iron would exceed the 5 or so grams that induce
exogenous or secondary acquired iron overload with tissue damage
(hemochromatosis), the ferromagnetic material is chemically
isolated by encapsulation metallic or polymeric. The source of iron
overload known, limited, and temporary rather than diagnostic for
chronic defective hematopoesis, anemia, (The Merck Manual of
Diagnosis and Therapy, 18th edition, pages 1131-1133) or infection,
so long as deposition remains at a concentration too small to do
tissue damage (hemosiderosis), treatment is not necessary.
[0441] Laser welding surgical tissue solder polymers (see, for
example, ACS [American Chemical Society] News Service Weekly
PressPac 2013. "Improved Material for `Laser Welding` of Tissue in
Intestinal Surgery," ACS News Service Weekly PressPac Wed May 8, at
https://www.acs.org/content/acs/en/pressroom/presspacs/2013/acs-presspac--
may-8-2013/improved-mater-ial-for-laser-welding-of-tissue-in-intestinal-su-
rgery.html) can release therapeutic drugs not altered by the heat
used to flow the solder (see, for example, Prosperi, D., Colombo,
M., Zanoni, I., and Granucci, F. 2017. "Drug Nanocarriers to Treat
Autoimmunity and Chronic Inflammatory Diseases," Seminars in
Immunology 34:61-67; Mundargi, R. C., Babu, V. R., Rangaswamy, V.,
Patel, P., d Aminabhavi, T. M. 2008 "Nano/Micro Technologies for
Delivering Macromolecular Therapeutics Using
Poly(D,L-lactide-co-glycolide) and Its Derivatives," Journal of
Controlled Release 125(3):193-209; Perugini, P., Genta, I., Conti,
B., Modena, T., and Pavanetto, F. 2001. "Long-term Release of
Clodronate from Biodegradable Microspheres," Pharm Sci Tech
2(3):E10). Small miniballs and stays can include or consist of
long-term drug release microspheres (see, for example, Varde, N. K.
and Pack, D. W. 2004. "Microspheres for Controlled Release Drug
Delivery, Expert Opinion on Biological Therapy 4(1):35-51) or nano
or microparticles (see, for example, Ravi Kumar, M. N. 2000. "Nano
and Microparticles as Controlled Drug Delivery Devices," Journal of
Pharmacy and Pharmaceutical Sciences 3(2): 234-58).
[0442] As used here, the term medication includes those--all of
which pose the risk of adverse side effects that if directly
targeted through use of the means described herein--would be
significantly lessened, antiangiogenic (antivasofactive),
proangiogenic, proneurogenic, chemotherapeutic, oncolytic viral,
antibiotic, precursory (prodrug, proenzyme, prohormone),
nanomedical, gene therapeutic to include ataxia-telangiectasia
mutated protein activating (see, for example, Comunanza, V. and
Bussolino, F. 2017. "Therapy for Cancer: Strategy of Combining
Anti-angiogenic and Target Therapies," Frontiers in Cell and
Developmental Biology 5:101; Kachaamy, T., Gupta, D., Edwin, P.,
and Vashi, P. 2017. "Safety of Endoscopy in Cancer Patients on
Antiangiogenic Agents: A retrospective Multicenter Outcomes Study,"
Public Library of Science One 12(5):e0176899; Tanabe, K., Maeshima,
Y., Sato, Y., and Wada, J. 2017. "Antiangiogenic Therapy for
Diabetic Nephropathy," BioMed Research International 2017:5724069;
Rajabi, M. and Mousa, S. A. 2017. "The Role of Angiogenesis in
Cancer Treatment," Biomedicines 5(2). pii: E34; Cao, Y. 2016.
"Future Options of Anti-angiogenic Cancer Therapy," Chinese Journal
of Cancer 35:21; Zhang, Q., Cao, J., Xue, K., Liu, X., Ji, D., Guo,
Y., and Hong, X. 2016. "Recombinant Human Endostatin in Combination
with CHOP [cyclophosphamide, doxorubicin, vincristine and
prednisone] Regimen for Peripheral T cell Lymphoma," OncoTargets
and Therapy 10:145-151; Vecchio, D. and Frosina, G. 2016.
"Targeting the Ataxia Telangiectasia Mutated Protein in Cancer
Therapy," Current Drug Targets 17(2):139-153; Kumar, A., Purohit,
S., and Sharma, N. K. 2016. "Aberrant DNA Double-strand Break
Repair Threads in Breast Carcinoma: Orchestrating Genomic Insult
Survival," Journal of Cancer Prevention 21(4):227-234; Ye, B., Hou,
N., Xiao, L., Xu, Y., Xu, H., and Li, F. 2016. "Dynamic Monitoring
of Oxidative DNA Double-strand Break and Repair in Cardiomyocytes,"
Cardiovascular Pathology 25(2):93-100; Farooqi, A. A., Attar, R.,
Arslan, B. A., Romero, M. A., ul Haq, M. F., and Qadir, M. I. 2014.
"Recently Emerging Signaling Landscape of Ataxia-telangiectasia
Mutated (ATM) Kinase," Asian Pacific Journal of Cancer Prevention
15(16):6485-6488; Andrs, M., Korabecny, J., Nepovimova, E., Jun,
D., Hodny, Z., and 3 others 2014. "The Development of Ataxia
Telangiectasia Mutated Kinase Inhibitors," Mini Reviews in
Medicinal Chemistry 14(10):805-811; Vasudev, N. S. and Reynolds, A.
R. 2014. "Anti-angiogenic Therapy for Cancer: Current Progress,
Unresolved Questions, and Future Directions," Angiogenesis
17(3):471-494; Elice, F. and Rodeghiero, F. 2012. "Side Effects of
Anti-angiogenic Drugs," Thrombosis Research 129 Supplement
1:S50-S53; Elice, F. and Rodeghiero, F. 2010. Bleeding
Complications of Antiangiogenic Therapy: Pathogenetic Mechanisms
and Clinical Impact," Thrombosis Research 125 Suppl 2:S55-S57;
Abdollahi, A. and Folkman, J. 2010. "Evading Tumor Evasion: Current
Concepts and Perspectives of Anti-angiogenic Cancer Therapy," Drug
Resistance Updates 13(1-2):16-28; Alexander, A., Cai, S. L., Kim,
J., Nanez, A., Sahin, M., and 9 others 2010. "ATM
[ataxia-telangiectasia mutated] Signals to TSC2 [tuberin, tuberous
sclerosis complex 2 protein encoded by the TSC2 gene] in the
Cytoplasm to Regulate mTORC1 [mammalian, or mechanistic, target of
rapamycin complex 1 protein] in Response to ROS [reactive oxygen
species]," Proceedings of the National Academy of Sciences of the
United States of America; Sordet, O., Redon, C. E.,
Guirouilh-Barbat, J., Smith, S., Solier, S., and 8 others 2009.
"Ataxia Telangiectasia Mutated Activation by Transcription- and
Topoisomerase I-induced DNA Double-strand Breaks," European
Molecular Biology Organization Reports 10(8):887-893; Morio, T. and
Kim, H. 2008. "Ku, Artemis, and Ataxia-telangiectasia-mutated:
Signalling Networks in DNA Damage," International Journal of
Biochemistry and Cell Biology 40(4):598-603; Juang, S. H., Lung, C.
C., Hsu, P. C., Hsu, K. S., Li, Y. C., and 16 others 2007.
"D-501036, a Novel Selenophene-based Triheterocycle Derivative,
Exhibits Potent in Vitro and in Vivo Antitumoral Activity which
Involves DNA Damage and Ataxia Telangiectasia-mutated Nuclear
Protein Kinase Activation," Molecular Cancer Therapeutics
6(1):193-202; Ismail, I. H., Nystrom, S., Nygren, J., and
Hammarsten, O. 2005. "Activation of Ataxia Telangiectasia Mutated
by DNA Strand Bbreak-inducing Agents Correlates Closely with the
number of DNA Double Strand Breaks," Journal of Biological
Chemistry 280(6):4649-4655).
[0443] Also included is in vivo magnetic assisted transfection of
small interfering (short interfering, silencing, knockdown)
ribonucleic acid (see, for example, Covarrubias, S., Robinson, E.
K., Shapleigh, B., Vollmers, A., Katzman, S., and 4 others 2017.
"CRISPR/Cas [clustered regularly-interspaced short palindromic
repeats/CRISPR-associated]-based Screening of Long Non-coding RNAs
(lncRNAs) in Macrophages with an NF-.kappa.B [nuclear factor
kappa-light-chain-enhancer of activated B cells] Reporter," Journal
of Biological Chemistry 292(51):20911-20920; Unniyampurath, U.,
Pilankatta, R., and Krishnan, M. N. 2016. "RNA Interference in the
Age of CRISPR: Will CRISPR Interfere with RNAi?," International
Journal of Molecular Sciences 17(3):291; Mykhaylyk, O.,
Sanchez-Antequera, Y., Vlaskou, D., Cerda, M. B., Bokharaei, M.,
and 3 others 2015. "Magnetic Nanoparticle and Magnetic Field
Assisted siRNA [small interfering or interference] Delivery in
Vitro," Methods in Molecular Biology (Clifton, N.J.) 1218:53-106;
Boettcher, M. and McManus, M. T. 2015. "Choosing the Right Tool for
the Job: RNAi [RNA interference], TALEN [transcription
activator-like effector nucleases], or CRISPR [clustered
regularly-interspaced short palindromic repeats]," Molecular Cell
58(4):575-585; Laurentt, N., Sapet, C., Le Gourrierec, L.,
Bertosio, E., and Zelphati, O. 2011. "Nucleic Acid Delivery Using
Magnetic Nanoparticles: The Magnetofection Technology," Therapeutic
Delivery 2(4):471-482; Plank, C., Zelphati, O., and Mykhaylyk, O.
2011. "Magnetically Enhanced Nucleic Acid Delivery. Ten Years of
Magnetofection-progress and Prospects," Advanced Drug Delivery
Reviews 63(14-15):1300-1331; Mykhaylyk, O., Zelphati, O.,
Hammerschmid, E., Anton, M., Rosenecker, J., and Plank, C. 2009.
"Recent Advances in Magnetofection and Its Potential to Deliver
siRNAs siRNA [small interfering or interference] in Vitro," Methods
in Molecular Biology (Clifton, N.J.) 487:111-146; Mykhaylyk, O.,
Zelphati, O., Rosenecker, J., and Plank, C. 2008. "siRNA Delivery
by Magnetofection," Current Opinion in Molecular Therapeutics
10(5):493-505; Kawakami, S. and Hashida, M. 2007. "Targeted
Delivery Systems of Small Interfering RNA by Systemic
Administration," Drug Metabolism and Pharmacokinetics
22(3):142-151), mutant human tumor necrosis factor (Liu, X., Zhang,
X. F., Zheng, Z. W., Lu, H., Wu, X., Huang, C., Wang, C., and
Guang, G. 2004. "The Effect of Chemotherapy Combined with
Recombination Mutant Human Tumor Necrosis Factor on Advanced
Cancer," Journal of Translational Medicine 2(1):33), glutamate
antagonistic, and/or irradiating.
[0444] Whether containing an irradiating seed, the surface of stay
and miniball implants, metallic, absorbable, or having an outer
absorbable layer or layers can be prepared to emit radiation (see,
for example, Cardoso, R. M., de Souza, C. D., Rostelato, M. E., and
Araki, K. 2017. "Highly Efficient Method for Production of
Radioactive Silver Seed Cores for Brachytherapy," Applied Radiation
and Isotopes 120:76-81; Li, Z. Y., Langhans, L., Klausen, T. L.,
Tvedskov, T. F., Talman, M. L., Oturai, P. S., Vejborg, I., Kroman,
N., and Hesse, B. 2016. "Preparation and Administration of I-125
Labeled Seeds for Localization of Nonpalpable Breast Lesions,"
Current Radiopharmaceuticals 9(2):143-149; Gao, H. B., Deng, X. S.,
Zhou, L., Zhang, W. H., Han, L. G., Jin, X. H., and Cui, H. P.
2015. "Preparation of (103)Pd Brachytherapy Seeds by Electroless
Plating of (103)Pd onto Carbon Bars," Applied Radiation and
Isotopes 103:128-130; Lee, J. H., Choi, K. H., and Yu, K. H. 2014.
"Surface Treatments of Silver Rods with Enhanced Iodide Adsorption
for I-125 Brachytherapy Seeds," Applied Radiation and Isotopes
85:96-100; Otani, Y., Yamada, T., Kato, S., Shikama, N., Funakoshi,
K., and 5 others 2013. "Source Strength Assay of Iodine-125 Seeds
Sealed within Sterile Packaging," Journal of Applied Clinical
Medical Physics 2013 14(2):4082; Fischell, T. A. and Hehrlein, C.
1998. "The Radioisotope Stent for the Prevention of Restenosis,"
Herz 23(6):373-379; Sekina, T., Watanabe, S., Osa, A., Ishioka, N.,
Koizumi, M. and 8 others 2001. "Xenon 133 Radioactive Stent for
Preventing Restenosis of Blood Vessels and a Process for Producing
the Same," U.S. Pat. No. 6,192,095). Apparatus according to the
invention allow the targeted delivery of medication into luminal
lesions endoluminally.
[0445] One type, barrel-assemblies, are catheteric extensions to
the barrel of a modified or special purpose interventional airgun.
This introduces the medication in the form of tiny spherules or
miniballs. Another type, radial projection assemblies or catheters
deliver medication endoluminally using side-looking, or luminal
wall-directed, injection microsyringes or hypotubers. Yet another
apparatus is a stay insertion hand tool that allows injection
extraluminally. The endoluminal types include barrel assemblies
such as shown in FIGS. 31 thru 35, and 38 thru 49 and 71b, and
radial projection catheters such as shown in FIG. 71a.
[0446] As shown in FIG. 71, which shows how these need not be
mutually exclusive, the radial projection catheter in FIG. 71a, for
example, devised to slide over, thereby to ensheath the
barrel-assembly of complementary conformation shown in FIG. 71b to
constitute a composite, duplex, or bipartite combination radial
projection catheter/barrel-assembly shown in FIG. 71c such the the
two can be used separately or as unitized. In numerous alternative
configurations where these are independent, either can include
features of the other. Such multifeatured transluminal catheters
are always ablation and angioplasty capable. The implants can
consist purely of medication or of ferrous cores or
radiation-emitting seeds enveloped within layers of medication, for
example.
[0447] By including ferromagnetic material, implants that are
mispositioned, dropped, or due for removal because the period for
treatment has ended are made retrievable or prevented from
continued movement with the aid of a magnet. Where barrel
assemblies are transluminal devices that introduce spherical
implants into the wall surrounding the lumen radially outward and
forward at an acute angle by aeroballistic ejection from within the
lumen, stay insertion devices insert tiny band shaped implants into
the luminal wall from outside the ductus. As addressed in section
XV5 below entitled Circumstances Dissuading or Recommending the Use
of Stays, this ability of the integrated system set forth herein to
accomplish implantation either from within or without the ductus
makes possible the secure and well placed positioning of the
implants in any anatomical context.
[0448] Since the stent-jacket must be placed from outside the
ductus in any event, the use of stays eliminates the need for
double, or transluminal approach, as well. In some anatomical and
pathological situations, one and the same ductus might best be
treated in part by either type device. As explicated herein,
provided it is warranted by the severity of the condition, the
advantages of a periductal stent-jacket over a conventional
endoluminal stent justify the dissection required to place the
jacket. By the same token, the endoluminal/extraluminal double
approach provided by the system described means that often,
extensive perivascular dissection to place magnetically susceptible
implants can be avoided. This double approach capability also means
that implantation can span the length of the defect and avoid
problems of conventional stenting, such as migration.
[0449] Endoluminal stent migration is no less a risk in the aortic
arch (see, for example, Rad, E. M., Mortezaeian, H., Pouraliakbar,
H. R., and Hijazi, Z. M. 2017, Op cit.; van den Hoven, A. T.,
Duijnhouwer, A. L., Eicken, A., Aboulhosn, J., de Bruin, C., and 9
others 2017. "Adverse Outcome of Coarctation Stenting in Patients
with Turner Syndrome," Catheterization and Cardiovascular
Interventions 89(2):280-287; Yaylali, Y. T., Evrengul, H., and
Uludag, B. 2013. "Successful Management of a Proximally Migrated
Stent in a Middle-aged Woman with Unnoticed Native Aortic
Coarctation," International Journal of Cardiology 168(1):e19-21;
Kannan, B. R. and Srinivasan, M. 2012. "Stent Migration During
Transcatheter Management of Coarctation of Aorta," Catheterization
and Cardiovascular Interventions 79(3):408-413; Forbes, T. J.,
Garekar, S., Amin, Z., Zahn, E. M., Nykanen, D., and 19 others
2007, Op cit.).
[0450] Whether additionally coated with medication or radioactive,
for example, miniballs, stays, magnet-jackets, stent-jackets, and
impasse-jackets can all be used to concentrate a drug carrier
nanoparticle or ferrofluid-bound drug or other therapeutic
substance such as small interfering ribonucleic acid passing in the
circulation and draw the drug abaxially (away from the long axis,
lateral, peripheral, outward) through the lumen wall into the
lesion. Permanent encirclement of the ductus by an expandable
collar, or stent-jacket, having a lining to protect the fine
vessels and nerves that surround the ductus and tiny magnets
mounted about its outer surface allows the implants to serve as the
intraductal component of an extraluminal stent. A structure
requiring stenting may have collapsed, become constricted
(stenosed, stenotic, stegnotic, strictured, coarctated, narrowed),
or have been alleviated of constriction or occlusion (blockage)
where the patency achieved must now be sustained.
[0451] Validation of stenting as efficacious in the treatment of
coarctation of the aorta extends the application of stents to this
congenital or `native` form of narrowing (stenosis, stricture,
constriction) (Bassiri, H. A., Abdi, S., Shafe, O., and Sarpooshi,
J. 2017. "Early and Midterm Results Following Interventional
Coarctoplasty: Evaluation of Variables that Can Affect the
Results," Korean Circulation Journal 47(1):97-106; Georgescu, A.,
Onorato, E., Nicolae, S., and Balnescu, S. 2015. "Aortic
Coarctation Treated by PTA and Stenting: A Case Presentation and
Literature Review," Maedica (Bucharest, Roma{circumflex over
(n)}ia) 10(4):342-347; Forbes, T. J. and Gowda, S. T. 2014, Op
cit.; Forbes TJ, Kim DW, Du W, Turner D R, Holzer R. J., Amin Z,
Hijazi Z, and 18 others 2011. "Comparison of Surgical, Stent, and
Balloon Angioplasty Treatment of Native Coarctation of the Aorta:
An Observational Study by the CCISC (Congenital Cardiovascular
Interventional Study Consortium)," Journal of the American College
of Cardiology 58(25):2664-2674; Holzer, R. J., Qureshi, S.,
Ghasemi, A., Vincent, J., Sievert, H., Gruenstein, D., Weber, H.,
and 6 others 2010. "Stenting of Aortic Coarctation: Acute,
Intermediate, and Long-term Results of a Prospective
Multi-institutional Registry--Congenital Cardiovascular
Interventional Study Consortium (CCISC)," Catheterization and
Cardiovascular Interventions 76(4):553-563).
[0452] If not conclusively successful, such application pertains
not only to neonates but to critically ill premature infants as a
bridging measure pending surgical reconstruction or recorrection
thereof where an earlier coarctectomy or repair of the interrupted
aortic arch had failed. Imperiling the left ventricle, which in an
effort of compensation to pass sufficient blood into the systemic
circulation, progressively weakens and hypertrophies, prominently
presenting as syncope, dyspnea, epistaxis, vertigo, hypertension of
the arms and hypotension of the legs, as well as other indications
of weakness (van den Hoven, A. T., Duijnhouwer, A. L., Eicken, A.,
Aboulhosn, J., de Bruin, C., and 9 others 2017. "Adverse Outcome of
Coarctation Stenting in Patients with Turner Syndrome,"
Catheterization and Cardiovascular Interventions 89(2):280-287;
Gorenflo, M., Boshoff, D. E., Forbes, T. J. and Gowda, S. T. 2014.
"Intravascular Stent therapy for Coarctation of the Aorta,"
Methodist Debakey Cardiovascular Journal 10(2):82-87; Heying, R.,
Eyskens, B., Rega, F., Meyns, B., and Gewillig, M. 2010. "Bailout
Stenting for Critical Coarctation in
Premature/Critical/Complex/Early Recoarcted Neonates,"
Catheterization and Cardiovascular Interventions 75(4):553-561;
Bentham, J., Shettihalli, N., Orchard, E., Westaby, S., and Wilson,
N. 2010. "Endovascular Stent Placement is an Acceptable Alternative
to Reoperation in Selected Infants with Residual or Recurrent
Aortic Arch Obstruction," Catheterization and Cardiovascular
Interventions 76(6): 852-859)
[0453] Pediatric application has also been successfully extended to
coronary and venous stenoses (see, for example, Aldoss, O., Arain,
N., Menk, J., Kochilas, L., and Gruenstein, D. 2014. "Endovascular
Stent Provides More Effective Early Relief of SVC [superior vena
caval Obstruction Compared to Balloon Angioplasty," Catheterization
and Cardiovascular Interventions 83(7):E272-E276; Bratincsak, A.,
Salkini, A., El-Said, H. G., and Moore, J. W. 2012. "Percutaneous
Stent Implantation into Coronary Arteries in Infants,"
Catheterization and Cardiovascular Interventions 79(2):303-311;
Stanfill, R., Nykanen, D. G., Osorio, S., Whalen, R., Burke, R. P.,
and Zahn, E. M. 2008. "Stent Implantation is Effective Treatment of
Vascular Stenosis in Young Infants with Congenital Heart Disease:
Acute Implantation and Long-term Follow-up Results,"
Catheterization and Cardiovascular Interventions 71(6):831-841;
Moodie, D. 2008. "Stent Implantation as Effective Treatment of
Vascular Stenosis in Young Infants with Congenital Heart Disease:
Acute Implantation and Follow-up," Catheterization and
Cardiovascular Interventions 71(6):842;). With an extraluminal
stent of the kind to be described, ferromagnetic implants
positioned beneath or subjacent to the outer fibrous coat or tunic
if not within deeper, that is, more adluminal or medial, tissue of
a tubular anatomical structure can be placed under the sustained
retractive force of minute surrounding magnets to maintain the
patency and thus sustain the movement of contents through the
structure.
[0454] The subject of stent migration addressed below, extraluminal
stents are easily provided with suture loops or suture eyelets and
end-ties for use as necessary to reinforce the positional stability
afforded by the spring hinges joining the half-cylinders and the
resistance to sliding afforded by the foam jacket lining. Except in
large gastrointestinal stents, such collateral tethering is not
possible when the stent is endoluminal, conventional stents
sometimes migrating to pose significant danger (see, for example,
Orellana-Barrios, M., Patel, N., Arvandi, A., Paone, R., and
Santana, D. 2017. "Venous Stent Migration into Right Ventricle,"
Cureus 9(8):e1583; Hayashi, T., Akhtar, S., and Alwi, M. 2017.
"Stent Migration After Right Ventricular Outflow Tract Stenting in
the Severe Cyanotic Tetralogy of Fallot Case," Annals of Pediatric
Cardiology 10(2):206-208; Garbey, M., Salmon, R., Fikfak, V., and
Clerc, C. O. 2016. "Esophageal Stent Migration: Testing Few
Hypothesis with a Simplified Mathematical Model," Computers in
Biology and Medicine 79:259-265; Moltzer, E., Ouhlous, M.,
Roos-Hesselink, J. W., Bogers, A. J., and Witsenburg, M. 2013.
"Proximal Aortic Stent Migration," Netherlands Heart Journal
21(11):517-519; Kobayashi, D., Singh, H. R., Turner, D. R., Forbes,
T. J., and Gowda, S. T. 2012. "Transcatheter Retrieval and
Repositioning of Embolized Stent from the Right Ventricle in an
Infant," Texas Heart Institute Journal 39(5):639-643).
[0455] For ductus that require clearing prior to stenting
implantation, the endoluminal apparatus incorporates radially
protrusible tools that can prepare the wall for treatment by
injection or wetting, for example, then shave, abrade, or scrape
(curet, evide) away adhesions or plaque along the lumen wall. The
extraluminal stents described herein eliminate the need to situate
a foreign object within the lumen and are intended to be usable in
any vas or ductus of any vertebrate that is wide enough in diameter
to admit the apparatus used to place the implants and provides a
wall thickness sufficient to accommodate these. That an endoluminal
stent must clog in the airway, especially when used for a chronic
congestive condition such as bonchiectasis, is indisputable. Any
endoluminal stent, regardless of the type ductus in which it is
placed, is susceptible to accretions, irritation, occlusion, and
migration (dislocation, displacement), and any of these, much less
its fracture, can result in serious consequences.
[0456] In the digestive tract, an endoluminal stent is often pushed
along by the passing contents as well as peristalsis, making
migration common unless the stent is fixed in position by stapling
or the use of more than one stent. Just as endoluminal stents,
extraluminal stents can be used to alleviate the symptoms of
tracheal or bronchial stenosis or collapse, obturate fistulas,
preserve the patency of blood vessels, and maintain the patency of
ureters and gamete transporting ducts, for example. Stenotic
conditions amenable to treatment with a stent exclude noncompliant
constrictions of the lumen due to a congenital malformation.
Elimination from the lumen eliminates contact with the healing
endothelium as well as the risks assocated with migration,
fracture, or fragmentation, and allows the stent to expand and
contract without stressing or deforming the ductus.
[0457] Intrinsically and quasi-intrinsically magnetized
stent-jackets, addressed below in the section entitled Types of
Stent-jacket, eliminate permanent magnets mounted about the outer
surface of a stent-jacket. The thinner stent-jacket with no outward
projections can be fitted to arteries ensheathed within muscle,
notably, to treat peripheral artery disease. Prepositioned
impasse-jackets allow continued drug targeting at any level along
any ductus to include such locations, as well as protect against
embolism by a miniball whether mid- or postprocedurally, and
whether the result of human error or a direct blow. Medicated and
irradiated stent-jackets are less and less limited to the
palliative and more and more able to effect an actual cure.
2. Preliminary Description of the Invention
[0458] Brief summaries are provided above in the abstract and below
in the section entitled Summary of the Invention. The invention
pertains to means for ablation or angioplasty as appropriate, the
targeting of drugs, and the infixion of tiny implants within organs
and in particular, into the walls of tubular anatomical structures,
to treat lesions or pathological conditions thereof, such as
stenosis or collapse. Whether the contents are medicinal,
irradiating, and/or ferromagnetic, the implants meant for infixion
within tissue such as ductus-intramural are distinguished by type
based upon conformation as either miniature balls, or miniballs,
which are spherules introduced from within the lumen, or as small
arcuate bands, or stays, which are introduced from outside the
outer fibrous jacket or tunic, the tunica fibrosa or adventitia, of
the organ, vessel, or duct. Such implants can be used for drug
delivery, drug targeting, and/or to stent.
[0459] Other implants to be described are collars or jackets for
placement about ductus which are used with these infixed implants
to retract the implants and thus act as a stent and/or to attract
drug delivery nanoparticles, microspheres, or miniballs via the
lumen. Miniballs and stays are alike only in positioning and
general functions. Miniballs are quickly placed from within the
lumen without the need for local access through a small or
laparoscopic incision. Placement thereof is prompted when an
antecedent procedure such as an angioplasty necessitates
transluminal (transcatheter) treatment in any event. Spheroidal for
ballistic delivery but poor for magnetic susceptibility, miniballs
are placed in relatively tight formation to uniformly distribute
the tractive force and avoid pull-through or delamination.
[0460] An extraluminal stent in the vascular tree leaves no foreign
object in the lumen, which is the central source of adverse
sequelae with endoluminal stents, to include reocclusion. Unless
placed in a surgical field opened for another reason, stays are
less quickly placed through an incision at the body surface than
are miniballs. Stenting with stays or miniballs not only avoids the
need to situate a foreign object in the lumen, but avoids the lumen
entirely. The result is a stent which is less likely to perpetuate
the chronic endothelial dysfunction that led to inflammation and
atheroma, fibroatheroma, or more complicated lesion, which
intervention and endoluminal stenting reinforces (see, for example,
Cui, Y., Liu, Y., Zhao, F., Shi, D., and Chen, K. 2016.
"Neoatherosclerosis after Drug-Eluting Stent Implantation: Roles
and Mechanisms," Oxidative Medicine and Cellular Longevity
2016:5924234; Veerasamy, M., Bagnall, A., Neely, D., Allen, J.,
Sinclair, H., and Kunadian, V. 2015. "Endothelial Dysfunction and
Coronary Artery Disease: A State of the Art review," Cardiology in
Review 23(3):119-129; Komiyama, H., Takano, M., Hata, N., Seino,
Y., Shimizu, W., and Mizuno, K. 2015. "Neoatherosclerosis: Coronary
Stents Seal Atherosclerotic Lesions but Result in Making a New
Problem of Atherosclerosis," World Journal of Cardiology
7(11):776-783; Rudolph, A., Teske, M., Illner, S., Kiefel, V.,
Sternberg, K., and 3 others 2015. "Surface Modification of
Biodegradable Polymers Towards Better Biocompatibility and Lower
Thrombogenicity," Public Library of Science One 10(12):e0142075;
Wang, X., Zachman, A, L., Chun, Y. W., Shen, F. W., Hwang, Y. S.,
and Sung, H. J. 2014. "Polymeric Stent Materials Dysregulate
Macrophage and Endothelial Cell Functions: Implications for
Coronary Artery Stent," International Journal of Cardiology
174(3):688-695; "Murase, S., Suzuki, Y., Yamaguchi, T., Matsuda,
O., Murata, A., and Ito, T. 2014. "The Relationship Between
Re-endothelialization and Endothelial Function After DES
[drug-eluting stent] Implantation: Comparison Between
Paclitaxcel-eluting Stent and Zotarolimus-eluting Stent,"
Catheterization and Cardiovascular Interventions 83(3):412-417;
Minami, Y., Kaneda, H., Inoue, M., Ikutomi, M., Morita, T., and
Nakajima, T. 2013. "Endothelial Dysfunction Following Drug-eluting
Stent Implantation: A Systematic Review of the Literature,"
International Journal of Cardiology 165(2):222-228; Gutierrez, E.,
Flammer, A. J., Lerman, L. O., Elizaga, J., Lerman, A., and
Fernandez-Aviles, F. 2013. "Endothelial Dysfunction Over the Course
of Coronary Artery Disease," European Heart Journal
34(41):3175-3181; Nakazawa, G., Otsuka, F., Nakano, M., Vorpahl,
M., Yazdani, S. K., and 4 others 2011. "The Pathology of
Neoatherosclerosis in Human Coronary Implants Bare-metal and
Drug-eluting Stents," Journal of the American College of Cardiology
57(11):1314-1322; Kim, J. W., Suh, S. Y., Choi, C. U., Na, J. O.,
Kim, E. J., and 4 others 2008. "Six-month Comparison of Coronary
Endothelial Dysfunction Associated with Sirolimus-eluting Stent
Versus Paclitaxel-eluting Stent," Journal of thd American College
of Cardiology Cardiovascular Interventions 1(1):65-71; Caramori, P.
R. A.; Lima, V. C.; Seidelin, P. H.; Newton, G. E; Parker, J. D;
Adelman, A. G. 1999. "Long-term Endothelial Dysfunction after
Coronary Artery Stenting," Journal of the American College of
Cardiology 34(6):1675-1679; van Beusekom, H. M., Whelan, D. M.,
Hofma, S. H., Krabbendam, S. C., van Hinsbergh, V. W., Verdouw, P.
D., and van der Giessen, W. J. 1998. "Long-term Endothelial
Dysfunction is More Pronounced after Stenting than after Balloon
Angioplasty in Porcine Coronary Arteries," Journal of the American
College of Cardiology 32(4): 1109-1117).
[0461] Some endothelial dysfunction is to be expected from
intervention of any kind (see, for example, Borovac, J. A.,
D'Amario, D., and Niccoli, G. 2017. "Neoatherosclerosis and Late
Thrombosis After Percutaneous Coronary Intervention: Translational
Cardiology and Comparative Medicine from Bench to Bedside," Yale
Journal of Biology and Medicine 90(3):463-470; Rudolph, A., Teske,
M., Illner, S., Kiefel, V., Sternberg, K., and 3 others 2015, Op
cit.); however, this should be significantly less with extraluminal
means, and remedial meaures are becoming apparent (see, for
example, Liu, H., Ba, P., Li, L., Wang, Y., Xu, C., Deng, M.,
Zhang, J., and Zhao, X. 2017. "Pitavastatin Nanoparticle-engineered
Endothelial Progenitor Cells Repair Injured Vessels," Scientific
Reports 7(1):18067; Lu, Q., Ye, F., Yang, X., Gu, Q., Wang, P.,
Zhu, J., Shen, L., and Gong, F. 2015. "Accelerated Recovery of
Endothelium Function After Stent Implantation with the Use of a
Novel Systemic Nanoparticle Curcumin," Biomed Research
International 2015:291871; Cerrato, E., Echavarria-Pinto, M.,
Tandjung, K., Macaya, C., and Escaned, J. 2014. "Optimizing Vessel
Healing Following Drug Eluting Stent Implantation with
Biodegradable Polymer DES [drug-eluting stent]," Minerva
Cardioangiologica 62(5):407-420; Hu, C. H., Ke, X., Chen, K., Yang,
D. Y., Du, Z. M., and Wu, G. F. 2013. "Transplantation of Human
Umbilical Cord-derived Endothelial Progenitor Cells Promotes
Re-endothelialization of the Injured Carotid Artery After Balloon
Injury in New Zealand White Rabbits," Chinese Medical Journal (in
English) 126(8):1480-1485; van den Heuvel, M., Sorop, O., van
Beusekom, H. M., and van der Giessen, W. J. 2009. "Endothelial
Dysfunction After Drug Eluting Stent Implantation," Minerva
Cardioangiologica 57(5):629-643).
[0462] Extended circumferentially and parallel to the substrate
ductus, stays provide more continuous expansive lifting and have
greater retentive ability, especially when coated with a cement
that prevents ductus wall failure. Nonabsorbable miniballs and
stays to be integrated into the surrounding tissue are provided
with an undercut textured surface. Stays are automatically coated
with a cement when ejected from the insertion tool that
incorporates tissue stimulating substances to encourage the gradual
infiltration and supplantation of the cement by tissue. To deliver
the cement with miniballs without fouling the airgun requires
followup injection with the aid of side-looking radial projection
unit injection tool-inserts, as addressed below in the section
entitled Self-contained Electrical/Fluid System-neutral
Tool-inserts, to Include Injection and Ejection Syringes or a
service catheter hypotube injector, as mentioned below in the
section entitled Risk of Abrupt Closure with Thrombus and
Vasospasm.
[0463] This depiction of a stent-jacket in FIG. 5 with small
permanent magnets mounted about its outer surface is presented for
clarity of the underlying concept; most stent-jacket achieve
uniformity of the magnetic tractive force without outward
protrusion of discrete magnets by embedding the magnetized material
within the jacket, as explained below in the section entitled Types
of Stent-jacket. Any of the implants to be described can be
magnetized for drug-targeting. If accidently dropped or
mispositioned, medicinal and/or irradiating miniballs and stays
include sufficient superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder to allow instant arrest and
retrieval using the recovery electromagnets of the recovery and
extraction miniball electromagnet assembly built into the insertion
apparatus, a separate caheteric probe with magnetized tip,
impasse-jackets prepositioned downstream precisely to truncate
further migration, or if necessary such as if embolizing, a
powerful external electromagnet positioned to suddently pull the
implant outside of the ductus or other structure.
[0464] Stent-jackets, addressed in the sections below entitled
Concept of the Extraluminal Stent and The Extraductal Component of
the Extraluminal Stent and the Means for Its Insertion among
others, rib-jackets addressed in the section below entitled Spine
and Ribs-type Stent-jackets, and magnet-jackets, or magnet-wraps,
addressed below in the section entitled Concept of the Magnet-wrap
represent a graduated series of type jackets based upon firmness or
backing firmness. Stent-jackets must possess the longitudinal and
circumferential firmness to stent, that is, to not flex inward
under the magnetic attractive force needed to draw the encircled or
substrate ductus-intramural implants radially outward.
Stent-jackets need not, however, be more firm than is necessary to
accomplish this as is based upon the retractive force needed to
keep the ductus patent.
[0465] Rib jackets are firm or firmly backed circumferentially but
not longitudinally as complies with peristalsis along the
gastrointestinal tract, or in miniature form, ureters and fallopian
tubes. Magnet jackets are stretchable in all directions as allows
complete compliance with the intrinsic movement within the
substrate ductus where the attractive force is applied at a
distance to affect magnetically susceptible implants fastened to or
infixed within distant tissue or draw susceptible matter such as
miniballs or nanoparticles from the substrate lumen contents where
that ductus is not collapsed, malacotic, or constricted. In
magnetic stenting or tissue retraction applications, the
ductus-intramural or intraductal implants include nonmagnetized
magnetically susceptible (ferrous) material, and are attracted or
drawn rather than attracting or drawing. That this relationship
might be reversed so that the implants were magnetized is
considered obvious. Miniballs and stays are not limited to magnetic
stenting or the retraction of tissue using magnetic force.
[0466] Either can incorporate ferromagnetic material for use with a
magnetic stent-jacket, medication, concentric layers of different
medication, a radionuclide, or a protein solder, for example, in
any combination, as well as include magnetically attracting or
attracted material for retrievability if dropped or mispositioned.
Implants to be fully absorbed omit magnetized content, which a
toxic lanthanoid (see, for example, Donohue, V. E., McDonald, F.,
and Evans, R. 1995. "In Vitro Cytotoxicity Testing of
Neodymium-Iron-Boron Magnets," Journal of Applied Biomaterials
6(1):69-74), is encapsulated for chemical isolation, usually with
gold plate, which is further treated to eliminate any voids or
surface residue, as addressed below in the section entitled
Stent-jackets and Stent-jacket Supportng Elements and is preferred
to the poly(p-xylylene.RTM.) AF-4 polymer (Paralyne) passivation
thin film commonly used to coat stents or polytetrafluoroethylene
(see, for example, Oje, A. M. and Ogwu, A. A. 2017. "Chromium Oxide
Coatings with the Potential for Eliminating the Risk of Chromium
Ion Felease in Orthopaedic Implants," Royal Society Open Science
4(7):170218; Aramesh, M., Tong, W., Fox, K., Turnley, A., Seo, D.
H., Prawer, S., and Ostrikov, K. K. 2015. "Nanocarbon-coated Porous
Anodic Alumina for Bionic Devices," Materials (Basel, Switzerland)
8(8):4992-5006; Liao, W. H., Lin, C. R., Wei, D. H., Shen, Y. R.,
Li, Y. C., Lee, J. A., and Liang, C. Y. 2012. "Concurrent
Improvement in Biocompatibility and Bioinertness of Diamond-like
Carbon Films with Nitrogen Doping," Journal of Biomedical Materials
Research. Part A 100(11):3151-3156; Wang, G. and Zreiqat, H. 2010.
"Functional Coatings or Films for Hard-tissue Applications,"
Materials (Basel, Switzerland) 3(7):3994-4050; Hinuber, C.,
Kleemann, C., Friederichs, R. J., Haubold, L., Scheibe, H. J., and
3 others 2010. "Biocompatibility and Mechanical Properties of
Diamond-like Coatings on Cobalt-chromium-molybdenum Steel and
Titanium-aluminum-vanadium Biomedical Alloys," Journal of
Biomedical Materials Research. Part A 95(2):388-400; Roy, R. K. and
Lee, K. R. 2007. "Biomedical Applications of Diamond-like Carbon
Coatings: A Review," Journal of Biomedical Materials Research. Part
B, Applied Biomaterials 83(1):72-84; Ahmad, K. A., Drummond, J. L.,
Graber, T., and BeGole, E. 2006. "Magnetic Strength and Corrosion
of Rare Earth Magnets," American Journal of Orthodontics and
Dentofacial Orthopedics 130(3):275.e11-5; Noar, J. H., Wahab, A.,
Evans, R. D., and Wojcik, A. G. 1999. "The Durability of Parylene
Coatings on Neodymium-iron-boron Magnets," European Journal of
Orthodontics 21(6):685-693).
[0467] Not limited to the walls of ductus, miniballs and stays can
be implanted anywhere in the body. The major categories of
miniballs and stays are absorbable (temporary, usually medicinal),
combination absorbable-nonabsorbable, which have a permanent or
intravascular ferromagnetic core, and nonabsorbable or permanent
used to secure a magnetic extraluminal stent of the kind to be
described. Temporary (absorbed) miniballs contain medication,
adhesives, or both. Temporary (absorbed) stays made of the same
materials that are used to make absorbable suture and tissue
engineering scaffolds can be used as buttress supports to sustain
the patency of a collapsed or stenosed lumen over the dissolution
period.
[0468] Any kind of stay can incorporate or be coated with
medication, foreign body tissue reaction suppressive substances,
such as dexamethasone, or an adhesive, or any combination of these.
Including sufficient ferromagnetic material such as magnetite or
maghemite nanoparticles or finely grained powder in an absorbable
stay or miniball assures retractability with a magnet.
Ductus-intramural implants (stays and miniballs) used as the
intraductal component of a magnetic stent contain a ferromagnetic
material, usually in the form of a core encapsulated within a
biocompatible chemical isolation layer. The core can be overlain
with additional layers of medication, a tumefacient, sclerosant,
adhesive, or any combination of these.
[0469] Such constituents can be dispersed or noncontinuous and
intermingled, so that rather than homogeneous, each layer might
include particles, microspheres, or nanorods of various therapeutic
substances (see, for example, Nabar, G. M., Mahajan, K. D.,
Calhoun, M. A., Duong, A. D., Souva, M. S., and 6 others 2018.
"Micelle-templated, Poly(lactic-co-glycolic Acid) Nanoparticles for
Hydrophobic Drug Delivery," International Journal of Nanomedicine
13:351-366; Zhu, X., Liu, C., Duan, J., Liang, X., Li, X., Sun, H.,
Kong, D., and Yang, J. 2016. "Synthesis of Three-arm Block
Copolymer Poly(lactic-co-glycolic Acid)-poly(ethylene Glycol) with
Oxalyl Chloride and Its Application in Hydrophobic Drug Delivery,"
International Journal of Nanomedicine 11:6065-6077; Cho, H., Gao,
J., and Kwon, G. S. 2016. "PEG-b-PLA Micelles and PLGA-b-PEG-b-PLGA
Sol-gels for Drug Delivery," Journal of Controlled Release
240:191-201; McKenzie, M., Betts, D., Suh, A., Bui, K., Tang, R.,
and 4 others 2016. "Proof-of-concept of Polymeric Sol-Gels in
Multi-Drug Delivery and Intraoperative Image-guided Surgery for
Peritoneal Ovarian Cancer," Pharmaceutical Research
33(9):2298-2306; Mundargi, R. C., Babu, V. R., Rangaswamy, V.,
Patel, P., and Aminabhavi, T. M. 2008. "Nano/Micro Technologies for
Delivering Macromolecular Therapeutics Using
Poly(D,L-lactide-co-glycolide) and Its Derivatives," Journal of
Controlled Release 125(3):193-209). The entire implant or its outer
layer can release a chemotherapeutic drug that also radiosensitizes
the targeted tissue, such as cisplatin, nimorazole, or cetuximab.
Just as with prior art seeds, radiation stays can incorporate
metals to aid in targeting intensity-modulated radiation therapy
(IMRT), for example.
[0470] Stays containing a radioactive seed also contain
ferromagnetic material, which if sufficient allows these to be used
as the intraductal component of a magnetic stent. Such stays can
likewise be coated with concentric layers each containing a drug or
drugs and/or other therapeutic substances. In the trachea and
bronchi, gastrointestinal tract, and many muscular arteries,
ferrous content allows any number of irradiating seed stays of
higher dose-rate than could be used if irretrievable to be
recovered at any time. Moreover, seed stays are implantable in
ductus walls more quickly than could be accomplished using
conventional means when these are even capable of placement thus.
Furthermore, unlike conventional seed implant devices, regardless
of its content, only the miniball or stay enters the tissue to be
treated, so that the penetration path or trajectory is no larger in
cross-section than is the implant itself.
[0471] By entering suddenly at high velocity, miniballs preempt the
evasive receding of flaccid tissue to effect infixion with minimal
tearing or stretching injury through a trajectory no wider than the
miniball itself. The sudden extraction or evulsion of a miniball as
addressed in section X2c below entitled Stereotactic Arrest and
Extraction of a Circulating, Dangerously Mispositioned, or
Embolizing Miniball is similarly intended to reverse the action of
aeroballistic infixion by preempting any ability of intervening
tissue to resist perforation. Loaded with sharp stays, a quick
action of the hand on the insertion tool produces the same result.
Properly applied, perforations of the ductus wall should seldom
occur. Stent-jacket and stay insertion tools generally incorporate
clips not included in the drawing figures for attaching alongside a
fine gauge endocscope with illumination, aspiration, cautery,
cryogenic, or heating line, or laser, for example, as
necessary.
[0472] Regardless of content, wider stays with a nonabsorbable
exterior and/or nonmagnetic can be used to maintain the patency of
a collapsed ductus by acting as mechanical supporting buttresses
without the need for a circumductal or extravascular collar type
stent component. In a magnetic stent, the ferromagnetic material in
the implant is attracted to small chemically isolated neodymium
iron boron lanthanoid magnets mounted:
[0473] 1. About an encircling (periductal, perivascular,
circumductal, circumvascular) stent-jacket, or
[0474] 2. To small platform base plates with prongs described below
in the section entitled Subcutaneous, Suprapleural, and Other
Organ-attachable Clasp- or Patch-magnets, or
[0475] 3. To magnet-wraps, described below in the section of like
title. As addressed below in the section entitled Significance of
SterileAntixenic Immune Tissue Reaction, to delay if not prevent a
foreign body reaction, implants and prongs that penetrate tissue to
secure implant backings in place are coated with
reaction-suppressive substances, such as phosphorylcholine,
dexamethasone, and/or curcumin.
[0476] The various components used may be classified as 1.
Transluminal, to include special catheters used as airgun barrels
(some also made angioplasty capable); 2. Intraductal, to include
miniballs and stays; or 3. Extraductal, to include stent-jackets,
clasp-wraps, and magnet-wraps. Completely extracorporeal are
modified commercial and dedicated interventional airguns and stay
insertion tools, to be described. Stent-jackets may be made
adaptive to the reduction in caliber of vasa with subsidence
(detumescence, regression) in an initially enlarged condition
thereof, while stays may be adaptive in partial or complete
dissolution over a controllable period. Stays and miniballs can
additionally be made to release medication or radiation. FIG. 1
shows the interrelations among the different type implants
described herein.
[0477] Pursuant to 37 CFR 1.475, the apparatus and methods go to a
group of interrelated devices and procedures that respond to a
single generative inventive concept and so conform to the
requirement for unity of invention. According to the medical
necessity, each and every element of the invention can have an
immediate and compulsory relation of combination with any of the
others, and none is used with devices not included in the system.
Self-contained and independent from the prior art, the system
provides all of the means essential to accomplish the type of
implantation it makes possible, to include site preparation,
implant infixion, and the implants themselves. Site preparation
includes the delivery of medication, atherectomy (atherotomy),
angioplasty, and ablation.
[0478] Other means described herein are ancillary but essential to
support these type implants, whether as insertion tools, adjuvant
medication, or as means for pretesting patient tissue in situ in
order to ascertain as best one might the prospective safety in
using these means, for example. Consistent with this unity in
conception, the various instruments and supplies described herein
can be combined in different ways, the medical circumstances
determining such use. That the attracting and attracted elements
described herein, specifically, magnets and nonmagnetized
ferromagnetic miniballs and stays respectively, could be reversed
to obtain the same result is considered obvious.
[0479] Implantation of miniballs by means of a specially adapted,
or interventional, airgun not only overcomes tissue flaccidity but
affords an implant loading point that proximate to the operator or
an assistant, allows immediate adaptation to the conditions
actually encountered following entry without the need to withdraw.
The implants tiny, such work is generally accomplished under
magnification, any accidental perforations quickly sealed
interventionally if not spontaneously. In most instances, the
implants will consist entirely of medication or of
radiation-emitting seeds with surrounding coats of medication for
localized placement within a circumscribed area, usually within the
wall of a tubular anatomical structure. The dose is thus
concentrated in or adjacent to the targeted tissue and minimized
for nontargeted tissue, whether by diffusion or through the
circulation. Reducing systemic dispersion before take-up allows
considerable reduction in the overall dose.
[0480] Delivery in this manner allows medication currently high in
cost, such as time-released trastuzumab with paclitaxel, for
example, conventionally administered by intravenous infusion with a
cremophore-containing vehicle that can cause hypersensitivity
reactions injection, or by release from an endoluminal drug-eluting
stent to treat an atheromatous lesion (Sauseville, E. A. and Longo,
D. L. 2005. "Principles of Cancer Treatment: Surgery, Chemotherapy,
and "Biologic Therapy," in Kaspar, D. L, Braunwald, E., Fauci, A.
S., Hauser, S. L., Longo, D. L., and Jameson, J. L., Harrison's
Principles of Internal Medicine, 16th Edition, New York, N.Y.:
McGraw-Hill, page 477), to be used efficiently, kept away from
nontargeted tissue, and applied to lesions surrounding lumina not
previously targetable. Dose minimization by targeting also results
in a reduction in side effects.
[0481] The use of an impasse-jacket as a holding jacket, as
addressed below in the section entitled Endoluminal Prehension of
Miniballs and Ferrofluids, to retain or draw a drug such as
paclitaxel administered in the form of a drug carrier nanoparticle
containing ferrofluid or in encapsulated microspheres from the
bloodstream for local infusion into an atheromatous plaque or
carcinoma is addressed in the sections below entitled Concept of
the Impasse-jacket and Interception and Recovery of a Miniball
Entering the Circulation. Implants containing ferromagnetic
material can be retrieved if dropped or if used to fully or
paritally encircle a ductus so that its wall can be retracted by
means of a mantling (periductal, perivascular, circumductal,
circumvascular) pliant jacket with a slit along one side having
tiny permanent magnets mounted about its outer surface.
[0482] The implants then constitute the intraductal or
ductus-intramural component of an extraluminal stent, the
extraductal component consisting of the immediately periductal
stent-jacket having the small permanent magnets mounted about it or
of small but slightly more powerful magnets implanted at a greater
distance by means of patch-magnets or magnet-jackets to be
described. To freely expand with the pulse and not interfere with
the contractive waves of peristalsis passing through, stent-jackets
are sized for the quiescent outer diameter of the ductus to be
treated, and for minimal mass and intracorporeal obstrusiveness as
might encroach upon or abrade neighboring structures, the bar
magnets mounted about the outer surface of the resilient segment of
tubing, or the base-tube, part number 5 in the drawing figues, are
of high energy product neodymium iron boron, which allows these to
be small and unobtrusive.
[0483] When properly matched to the collapsed or stenotic ductus,
the stent-jacket retracts the implanted wall outwards to the proper
quiescent diameter. Elastic, the jacket expands up to the maximum
diameter of the ductus (such as on the systoles). Because veins are
substantialliy inert, stent-jackets, clasp-wraps, and
magnet-jackets placed on veins, unlike arteries and peristaltic
ductus, can be coated on the inner surface with a surgical adhesive
when placed. A stent-jacket used as a circumvascular or
circumtracheal stent can be inserted through one or two incisions
that are smaller than the incisions required by conventional open
procedures and secured by means of end-ties (addressed below).
Because repair tends to be deferred until the patient is older and
impaired, the lesser trauma is significant.
[0484] The nontransluminally delivered extraductal components to be
described herein--stent-jackets, stays, clasp-wraps, and so
on--allow passage through an entry wound smaller in size than does
conventional open repair, typically a small (stab, "keyhole,"
"bandaid," or laparoscopic) incision, or microincision. Applied to
a procedure of like objective as a surgical atherectomy, an
atherectomy accomplished transluminally avoids the need for an
incision, and also allows extraluminal stenting through such a
small incision. When for any reason ballistic implantation is
contraindicated, a plurality of arcuate stent-stays containing
ferrous metal or a clasp-wrap, likewise used with a stent-jacket,
can be manually inserted into the wall of the ductus through a
local incision, stays by means of special hand tools to be
described.
[0485] Endoluminal and extraluminal tests are provided in the
sections below entitled In Situ Test upon Endoluminal Approach for
Intra- or Inter-laminar Separation (Delamination, Laminar Avulsion)
and in Situ Test upon Extraluminal Approach for Intra- or
Inter-laminar Separation (Delamination, Avulsion) for separation
within a tunic (intralaminar or intratunical separation) or between
tunics (interlaminar or intertunical separation, dilaceration, or
avulsion, decollement; delamination), such as between the
adventitia and the media. The test is intended to determine whether
spherules, stays, or a clasp-wrap, can be used at all, if so, at
what depth into the ductus wall the type that is most suitable
should be implanted, with or without the aid of a surgical
adhesive. The result may determine, for example, that no type of
implant can be placed subadventitially, so that the implant must be
implanted within the media.
[0486] When transluminal access is best avoided, stays, which are
placed inside the ductus wall, or a clasp-wrap, which that
encircles and engages the ductus from without, each of which is
inserted through the same local incision as the stent-jacket, are
used. A clasp-wrap, as addressed below in the section of like
title, is an alternative means for introducing ferromagnetic
implants into the wall of a ductus when the adventitia is too
weakened (softened, malacotic, malacic) for ballistic implantation.
Clasp-wraps are similar to stays in being applied from outside the
ductus, which eliminates the need for transluminal access. However,
these differ in attaching the ferromagnetic implants to an elastic
backing that aids retention by a weakened adventitia, and in
applicability only to ductus which can be fully encircled.
[0487] In most situations, especially when to serve as the
intraductal component of a magnetic stent, either miniballs or
stays will be better suited to the condition presented, the use of
both exceptional, and in the same ductus, seldom to be expected;
however, individual implants of the kind chosen can differ in
medication or other therapeutic substances contained. When an open
surgical field has not already been cleared, to implant stays
requires access to the target ductus through a small incision from
outside the body. Approach thus avoids the lumen entirely both
during placement and as infixed. This means that no foreign object
is inserted into the lumen, and that in a blood vessel, the
compresence of an infectious pathogen bacterial, mycotic, or viral,
will not provide a pathway into the ductus wall.
[0488] For the placement of medication implants which are fully
absorbed, access through an external incision is generally less
attractive than is the endoluminal delivery of miniballs. For
stenting, however, especially where an angioplasty is unnecessary,
the intraductal component is usually permanent, and to place the
stent-jacket requires an incision from the outside anyway, making
the use of stays overall less intrusive. Unless the miniball or
stay subadventital or subfibrosal implants are drawn outwards
towards the inner surface of the stent-jacket noncompressively with
little damage to vasa and nervi vasorum, the adverse sequelae of
endothelial dysfunction, atheromatous lesioning, and a loss in wall
strength will ensue. Damage to the vasa vasorum in third stage
syphilis, for example, results in aortic aneurysm.
[0489] Lining the side-slitted and perforated jacket with moisture
barrier-coated nonbiodegradable or bioresistant moisture barrier
moisture protection-coated visco-elastic polyurethane, or
viscoelastic polyurethane foam, for example, averts perivascular or
periductal compression of the microvasculature and small nerves
about the periphery of the ductus, and providing cutouts
(perforations, portals), allows some nonenclosure of the outer
surface of the ductus, allowing gas exchange and evaporation from
the outer surface of the ductus, or adventia.
[0490] While shape memory is not synonymous with fine shape
accommodation or compliance, alternative shape-memory materials are
under development which do or should eventually satisfy this
requirement (see, for example, Zhang, K., Feng, X., Ye, C.,
Hempenius, M. A., and Vancso, G. J. 2017. "Hydrogels with a Memory:
Dual-Responsive, Organometallic Poly(ionic Liquid)s with Hysteretic
Volume-Phase Transition," Journal of the American Chemical Society
139(29):10029-10035; Lowenberg, C., Balk, M., Wischke, C., Behl,
M., and Lendlein, A. 2017. "Shape-memory Hydrogels: Evolution of
Structural Principles to Enable Shape Switching of Hydrophilic
Polymer Networks," Accounts of Chemical Research 50(4):723-732;
Landsman, T. L., Touchet, T., Hasan, S. M., Smith, C., Russell, B.,
and 3 others 2017. "A Shape Memory Foam Composite with Enhanced
Fluid Uptake and Bactericidal Properties as a Hemostatic Agent,"
Acta Biomaterialia 47:91-99; Walker, R. M., Gillespie, B. M.,
Thalib, L., Higgins, N. S., and Whitty, J. A. 2017. "Foam Dressings
for Treating Pressure Ulcers," Cochrane Database of Systematic
Reviews 10:CD011332; Chan, B. Q., Low, Z. W., Heng, S. J., Chan, S.
Y., Owh, C., and Loh, X. J. 2016. "Recent Advances in Shape Memory
Soft Materials for Biomedical Applications," American Chemical
Society Applied Materials and Interfaces 8(16):10070-10087; Hardy,
J. G., Palma, M., Wind, S. J., and Biggs, M. J. 2016. "Responsive
Biomaterials: Advances in Materials Based on Shape-memory
Polymers," Advanced Materials (Deerfield Beach, Fla.)
28(27):5717-5724; Ebara, M. 2015. "Shape-memory Surfaces for Cell
Mechanobiology," Science and Technology of Advanced Materials
16(1):014804).
[0491] Absorbable materials of this kind are also under development
(see, for example, Balk, M., Behl, M., Wischke, C., Zotzmann, J.,
and Lendlein, A. 2016. "Recent Advances in Degradable Lactide-based
Shape-memory Polymers," Advanced Drug Delivery Reviews
107:136-152). Absorbable stent and impasse-jackets use
biodegradable shape memory foam (Peterson, G. I., Dobrynin, A. V.,
and Becker, M. L. 2017. "Biodegradable Shape Memory Polymers in
Medicine," Advanced Healthcare Materials 6(21); Singhal, P., Small,
W., Cosgriff-Hernandez, E., Maitland, D. J., and Wilson, T. S.
2014. "Low Density Biodegradable Shape Memory Polyurethane Foams
for Embolic Biomedical Applications," Acta Biomaterialia
10(1):67-76).
[0492] The moisture barrier prevents the breakdown products of the
viscoelastic polyurethane foam from being released into the
surrounding tissue and bloodstream where it is toxic, as was the
problem with earlier breat implants. Any polymerization process
residue or plasticizer must be thoroughly removed. The presence of
toxic residues from polymerization of moisture barrier-coated
viscoelastic polyurethane foam linings can be averted with suitable
preliminary cleaning of the material (see Maxwell, G. P. and
Gabriel, A. 2017. "Breast Implant Design," Gland Surgery
6(2):148-153; Daka, J. N. and Chawla, A. S. 1993. "Release of
Chemicals from Polyurethane Foam in the M me Breast Implant,"
Biomaterials, Artificial Cells, and Immobilization Biotechnology;
21(1):23-46).
[0493] The polyurethane foam used in stent- and impasse-jackets is
enveloped within a shape compliant moisture barrier that affords
additional protection from any breakdown products of the primary
component. Even were the same polyurethane foam used as that in the
breast implants withdrawn from the market in 1991, the release of
2,4-toluenediamine (TDA) from the foam lining of a stent-jacket,
impasse-jacket, or outrigger, which is minute in amount compared to
that in a breast implant, would be too little to act as a
carcinogen. That is, the absolute volume of the material in any of
the jackets described herein is minute compared to that in a breast
implant, making it improbable that its degredation would release an
amount of the material that would accede to a toxic burden (see,
for example, Pompei, S., Evangelidou, D., and Ferrante, G. 2017.
"Comments on "Commentary On: The Modern Polyurethane-coated Implant
in Breast Augmentation: Long-term Clinical Experience," Aesthetic
Surgery Journal 37(5):NP56-NP57; Frame, J. 2016. "Commentary On:
The Modern Polyurethane-coated Implant in Breast Augmentation:
Long-term Clinical Experience," Aesthetic Surgery Journal
36(10):1130-1132; Pompei, S., Evangelidou, D., Arelli, F., and
Ferrante, G. 2016. "The Modern Polyurethane-coated Implant in
Breast Augmentation: Long-term Clinical Experience," Aesthetic
Surgery Journal 36(10):1124-1129; Vazquez, G. and Pellon, A. 2007.
"Polyurethane-coated Silicone Gel Breast Implants Used for 18
Years," Aesthetic Plastic Surgery 31(4):330-336; Kulig, K. 1998.
"Lifetime Risk from Polyurethane Covered Breast Implants,"
Environmental Health Perspectives 106(11):A526-A527; Hester, T. R.
Jr., Ford, N. F., Gale, P. J., Hammett, J. L., Raymond, R.,
Turnbull, D., Frankos, V. H., and Cohen, M. B. 1997. "Measurement
of 2,4-toluenediamine in Urine and Serum Samples from Women with M
me or Replicon Breast Implants," Plastic and Reconstructive Surgery
100(5):1291-1298). Signifiantly, as addressed below in the sections
entitled Absorbable Base-tube and Stent-jacket; Miniball, Stay, and
Clasp-magnet Matrix Materials; Significance of Sterile Antixenic
Immune Tissue Reaction; and Materials Suitable for
Rebound-directing Double-wedge Linings, among others, means for
encouraging or forestalling attack by the immune system allow the
rate of breakdown and persistence of implanted polyurethane to be
widely adjusted.
[0494] Furthermore, a rate of chemical breakdown of 0.8 percent per
year (Benoit, F. M. 1993. "Degradation of Polyurethane Foams Used
in the M me Breast Implant," Journal of Biomedical Materials
Research 27(10):1341-1348) or alteration in cushioning properties
exhibited by existing materials allows many years of use, and the
presence of TDA or any other toxic product of foam degradation is
readily detectable through urinalysis (Shanmugam, K., Subrahmanyam,
S., Tarakad, S. V., Kodandapani, N., and Stanly, D. F. 2001.
"2,4-Toluene Diamines--Their Carcinogenicity, Biodegradation,
Analytical Techniques and an Approach towards Development of
Biosensors," Analytical Sciences 17(12):1369-1374; Santerre, J. P.,
Woodhouse, K., Laroche, G., and Labow, R. S. 2005. "Understanding
the Biodegradation of Polyurethanes: From Classical Implants to
Tissue Engineering Materials," Biomaterials 26(35):7457-7470). Soy
based foam is rejected as allergenic. Continued work should further
improve the longevity of polyurethane foam (see, for example,
Puskas, J. E. and Luebbers, M. T. 2012. "Breast Implants: The Good,
the Bad and the Ugly. Can Nanotechnology Improve Implants?," Wiley
Interdisciplinary Reviews. Nanomedicine and Nanobiotechnology
4(2):153-168, bottom left page 155; Handel, N. 2006. "Long-term
Safety and Efficacy of Polyurethane Foam-covered Breast Implants,"
Aesthetic Surgery Journal 26(3):265-274).
[0495] As used here, tissue reaction and infiltration into the
closed cell material should not be problems as require surface
treatment to lessen if not prevent; the foam is not embedded within
but merely makes contact with the tissue, and the tissue contacted
is intact, not injured, or granulated, and rapidly proliferating to
heal at the interface with the foam. The same nonembedded condition
that tends to retard the spontaneous absorption of absorbable
materials also alleviates degradation of the urethane.
[0496] Furthermore, the junction between adventitia and foam is not
compressive as with `negative pressure wound therapy` where bandage
lining ingrowth discourages the use of urethane. Whether to use
miniballs or stays is determined on the basis of the overall
medical considerations to include site accessibility. When not
practically accessible from without (extracorporeally),
implantation is of miniballs transluminally by means of a special
catheter devised to serve as an extension to the barrel of a
specially adapted semiautomatic gas-operated implant insertion
airgun.
[0497] Such a specialized catheter, consisting of a unitized
barrel-catheter and distal muzzle-head, is referred to as a
barrel-assembly. Practical barrel-assemblies encompass multiple
endoluminal capabilities. The airgun projects the spherules through
the barrel-assembly and out the muzzle-head at its distal end at an
acute forward angle, preferably to a point subjacent to
(underlying) the outer fibrous sheath of the ductus, the tunica
adventitia or tunica fibrosa in the trachea, or the tunica
adventitia or tunica externa in blood vessels, for example. When
the discharge velocity is set within the allowable range, which is
tested beforehand, the elastic layers in the wall of the ductus
prevent puncture. The miniballs are so small that unless the
patient has been heavily anticoagulated, spontaneous sealing is
prompt. Also, the risk of injury to neighboring tissue is
negligible. Exceptionally, the implants are placed more deeply
(adluminally, medially).
[0498] Viscoelastic polyurethane foam linings are addressed below
in the sections entitled Requirement for Moisture Barrier-coated
Viscoelastic Polyurethane Foam Linings and Stent- and Shield-jacket
Moisture Barrier-coated Viscoelastic Polyurethane Foam Linings.
When placed in a wet location, such linings have a typically
vapor-deposited or sputtered moisture barrier. Not introduced into
the bloodstream, stays reduce if not eliminate the need for
systemic medication to suppress clotting, and are therefore to be
preferred when the prospect of surgery is pronounced. When such is
not the case, the length of the segment to be implanted is
extensive, and procedural time with general anesthesia would best
be minimized, miniballs are preferable to stays.
[0499] In that case, combinations of a systemically circulated
anticoagulant where each implant has been coated with a reversal
agent for hemostasis in the event of an accidental
perforation--such as warfarin-vitamin K as phytonadione,
anti-inhibitor coagulant complexes, or systemic heparin with
protamine sulfate--will be too slow-acting. Provided it is
sufficiently pliant to comply in investing the small vessels and
nerves about the ductus, the hermetic, such as chemical vapor
deposited highly plasticized (Parylene.RTM. C or N), coating, which
completely biocompatible, is used to coat numerous implants such as
stents (see, for example, Schwarz, J. A., Contescu, C. I., and
Putyera, K. 2004. Dekker Encyclopedia of Nanoscience and
Nanotechnology, Volume 1, page 263, Boca Raton, Fla.: Chemical
Rubber Company Press), protects the foam from moisture
breakdown.
[0500] The same treatment when applied to the outside of the
jackets described herein will inhibit the deposition of clot, and
prevent the catching onto or abrasion of neighboring tissue, as
well as prevents fluid infiltration. In the mainlines, this
prevents extravasation, and in the sidelines, fluid infiltration or
leakage, assuring that dosing is accurate. Such a physical vapor
deposited coating can be provided by several companies to include
Acree Technologies Incorporated, Concord, Calif., Para-Coat
Technologies, Johnstown, Pa., and KDF Electronic and Vacuum
Services Incorporated, Rockleigh, N.J. Where the ductus is
sufficiently exposed to serous fluid, for example, as to be quite
wet, a hand dryer is used to remove most of the moisture before
placing the side-entry jacket or nonjacketing side-entry
connector.
[0501] Instead, a systemic antiplatelet blocker is administered and
the miniballs coated with a fast-acting reversal agent or hemostat,
such as kaolin (Al2Si2O5(OH)4) (Trabattoni, D., Gatto, P., and
Bartorelli, A. L. 2012. "A New Kaolin-based Hemostatic Bandage Use
after Coronary Diagnostic and Interventional Procedures,"
International Journal of Cardiology 156(1):53-54; Kheirabadi, B.
S., Scherer, M. R., Estep, J. S., Dubick, M. A., and Holcomb, J. B.
2009. "Determination of Efficacy of New Hemostatic Dressings in a
Model of Extremity Arterial Hemorrhage in Swine," Journal of Trauma
67(3):450-460; Politi, L., Aprile, A., Paganelli, C., Amato, A.,
Zoccai, G. B., and 5 others 2011. "Randomized Clinical Trial on
Short-time Compression with Kaolin-filled Pad: A New Strategy to
Avoid Early Bleeding and Subacute Radial Artery Occlusion after
Percutaneous Coronary Intervention," Journal of Interventional
Cardiology 24(1):65-72; Griffin, J. H. 1978. "Role of Surface in
Surface-dependent Activation of Hageman Factor (Blood Coagulation
Factor XII;" Proceedings of the National Academy of Sciences of the
United States of America 75(4):1998-2002; Walsh, P. N. 1972. "The
Effects of Collagen and Kaolin on the Intrinsic Coagulant Activity
of Platelets. Evidence for an Alternative Pathway in Intrinsic
Coagulation Not Requiring Factor XII," British Journal of
Haematology 22(4):393-405) or methyl prednisolone (Qureshi, A. I.
and Suri, M. F. 2008. "Acute Reversal of Clopidogrel-related
Platelet Inhibition Using Methyl Prednisolone in a Patient with
Intracranial Hemorrhage," American Journal of Neuroradiology
29(10):e97).
[0502] More specifically, the coating includes adenosine
diphosphate, fibrin, and a kaolinite-derived aluminosilicate
nanoparticlate. The insoluble kaolin coagulant is chemically inert
and becomes embedded within the surrounding tissue. In an
extraction from an impasse-jacket using a powerful external
electromagnet, the extraction is stereotactically oriented to avoid
any vulnerable structures. In blood vessels no anticoagulant is
administered, and sealing occurs quickly. In other type ductus,
problematic leakage can be averted by placing an absorbable
shield-jacket. If the application involves the placement of a
circumvascular jacket, the extent of dissection is much the same
whether stays or miniballs are used. Accidental perforation through
the ductus wall by a miniball discharged at too high a velocity or
normal (perpendicular) to the axis of the ductus ordinarily seals
spontaneously as to pose no threat. If, however, a vulnerable
neighboring structure such as a ganglion might be struck or septic
contents allowed to spill out of the lumen, a shield-jacket is
used. Radiation shield-jackets can be used with seed stays as well
as miniballs.
[0503] Broadly, the apparatus used to place the implants of the
ductus-intramural component of the extraluminal magnetic stents to
be described and the applications most suited to various
embodiments of these fall into three categories:
[0504] 1. The air pistol as modified for interventional use,
addressed below in the section entitled Modification of Commercial
Airguns, with a simple pipe-type barrel-assembly, addressed below
in the section entitled Simple Pipe Type Barrel-assemblies,
suitable, for example, for use in the airway where a. The anatomy
is differentiated or structured, b. The implants must be accurately
placed in relation thereto with the exit port easily viewed, c. The
larger size of the lumen allows the apparatus to be positioned
without injury to the lumen wall, and d. Sufficient speed with
precision does not require multiple discharge. To make possible the
accuracy required, a simple pipe will usually have a fiberoptic
endoscope, or angioscope, permanently attached, or where the
viewing device is costly and wanted for use with more than one
barrel-assembly, lashed alongside. As with the wires for the
recovery electromagnet and any bounce-plate device as shown in
FIGS. 35, 36, and 37, these cannot continue into the airgun barrel.
The electrical connection for the electromagnet is of the form
shown in FIG. 75.
[0505] 2. The dedicated interventional airgun with a radial
discharge barrel-assembly, generally for use in a lumen that unlike
the trachea, for example, is relatively undifferentiated or uniform
in structure, wherein the need for speed is greatest in blood
vessels, the carotid and coronary arteries in particular. Ablation
and ablation and angioplasty-capable barrel-assembly muzzle-heads
enclose the barrel-tubes within a torpedo-shaped outer shell and
discharge radially, or more accurately, frontoradially. To be
usable in blood vessels, barrel-assemblies must include gas
pressure diversion channels. Thus, a barrel-assembly capable of
performing an angioplasty will always be capable of performing an
ablation in a ductus of arterial diameter. Ablation and ablation
and angioplasty-capable barrel-assemblies are also classified
according to whether these are for use during and solely as an
adjunct to discharge while engaged in and dependent upon the airgun
for power and control, or whether these can be used as standalone
means for ablation or angioplasty.
[0506] 3. The manual insertion of stays, which inserted from
outside the ductus, avoids not only the numerous disadvantages of
placement of a foreign body within the lumen but also any
complications that might arise from the ballistic placement of
miniballs in a lumen carrying infectious or septic contents. Placed
with less speed, stays avoid the lumen entirely, can often be
placed laparoscopically under a local anesthetic, and therefore
mitigate the need for speed.
[0507] A more detailed breakdown of barrel-assemblies by type is
provided below in the section entitled Types of Barrel-assemblies.
An ablation or ablation and angioplasty-capable barrel-assembly is
equipped to perform an endoluminal ablation or an angioplasty or
atherectomy independently of and without connection to an airgun.
Another device, a radial projection catheter, addressed below in
the section entitled Radial projection catheters, when matched in
size to the barrel-assembly, can be slid over to ensheath, or
ensleeve, the barrel-assembly, thereby supplementing the number of
side-looking (lumen wall-radially directed) ablation or angioplasty
tool lift-shafts integral to the barrel-assembly muzzle-head.
[0508] To allow discharge at a greater distance down a narrowing
lumen, the portion of the muzzle-head distal to or forward of the
miniball discharge exit-port or ports is kept short. Keeping the
muzzle-head small in diameter allows access to lumina of smaller
caliber and allows the pulse to force blood past a muzzle-head that
completely occludes the lumen of a nonarteriosclerosed elastic
artery. Bipartite or duplex radial projection catheters can be slid
over the barrel-catheter of a barrel-assembly to add radial
projection units or be used separately to perform an angioplasty.
In nonelastic arteries, occlusive diameter must be compensated for
with blood-grooves that run the length of the muzzle-head, for
example. Radial projection unit push-arm tool-inserts can nudge the
muzzle-head to a side to let blood pass.
[0509] Combination-forms with side-ports can pass blood through the
bore, and provided the lumen wall stength test addressed below
under the section entitled In Situ Test on Endoluminal Approach for
Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation indicates that the ductus is unlikely to incur
stretching or dissection injury, a hand-held external electromagnet
as specified below in the section entitled Use of an External
Electromagnet to Assist in Steering or in Freeing the Muzzle-head
can be used as addressed below in this section to increase or
create a gap for lumen contents to pass. Multiple push-arm type
radial projection unit tool-inserts, addressed below in the
sections entitled Push-arm Radial Projection Unit Tool-inserts and
Ablation and Angioplasty-incapable Radial Discharge Barrel-assembly
Muzzle-heads, among others can be used to like effect.
[0510] Such a combination constitutes a bipartite or duplex
ablation or ablation and angioplasty-capable barrel-assembly, in
which the apportionment of side-looking tool lift-shafts, or radial
projection units, as between the muzzle-head and radial projection
catheter vary inversely within the sum total for the two as a unit.
Thus, at one extreme, the muzzle-head might include so large a
number of radial projection units as never to require
supplementation by ensheathment within a radial projection
catheter, while at the opposite extreme, the muzzle-head includes
no radial projection units, so that any must be obtained through
ensheathment. A radial projection catheter at this level of
sufficiency can perform an ablation or an angioplasty as an
independent device; however, it is not a barrel-assembly and cannot
implant miniballs.
[0511] To minimize hindrance in steering, and tracking, the
unsheathed component of a bipartite or duplex barrel-assembly is
usually first positioned at the treatment site, after which the
matching radial projection cathetetic component is slid over the
barrel-catheter using it as a guide wire to abut against the rear
of the muzzle-head. The radial projection catheter can then be
withdrawn and replaced with the same or another sheath without
moving the muzzle-head. Unless the radial projection catheter is of
the through-bore or combination-form type, it must be withdrawn to
allow a barrel-assembly to be introduced for initiating stenting
discharge.
[0512] By contrast, whether an ablation or an ablation and
angioplasty-capable barrel-assembly achieves this capability with
radial projection units built into its muzzle-head or by acquiring
these through the addition of a radial projection catheter, it need
not be withdrawn from the ductus and reinserted through the
introducer sheath before the muzzle-head at its distal end is
passed transluminally to the segment to be treated to initiate
stenting implantation. Radial projection catheters are addressed
below in the section of like title. Following treatment with the
ablation or ablation and angioplasty-capable barrel-assembly while
unconnected to the airgun, the free (proximal, extracorporeal) end
of an barrel-assembly is inserted into the barrel of the
airgun.
[0513] Such a barrel-assembly to which is added a
through-and-through passageway or central channel along the central
axis and an extracorporeal end- or side-socket through which to
pass a cable from a control console is referred to as a
through-bore or combination-form barrel-assembly. Such a
barrel-assembly allows the insertion through the central bore of a
fiberoptic or video endoscope, rotational atherectomy burr, or
excimer laser, for example. Even though a negligible accumulation
of debris generally exerts little practical effect on miniball exit
velocity, the barrel-assembly must be configured to minimize the
entry of debris through the exit ports during transluminal
advancement.
[0514] To minimize the risk of hypoxia, gas embolism, traumatizing
parectasia (overdistention, overstretching), and dissections, a
barrel-assembly for use in the vascular tree must further
incorporate internal gas pressure relief and other features to be
described, platelet blockade used to prevent the formation of
microthrombi at the sites of miniball entry. Venting the column of
air in the barrel-tube or tubes also reduces resistance to miniball
travel, especially when the barrel-assembly is inserted against the
flow and discharged during the pulse, thereby allowing the use of
an airgun that generates expulsive force less than would be
necessary otherwise.
[0515] Transluminal movement to another site for implantation is
usually by means of a stepper or 3-phase brushless synchronous iron
core linear motor-driven precision machining linear positioning
stage (linear stage, translation stage, linear table). Positional
control also makes it possible to lay down tight formations of
miniballs for the more uniform distribution of magnetic pull, and
if the miniballs are coated, then a more even distribution and
accurate targeting of the coating substances. Conventional vascular
cryoplasty and thermoplasty consist of running chilled or heated
fluid through an angioplasty balloon with the primary object of
structurally degrading the plaque so that dissections are minimized
and the dilatation forces exerted by the balloon meet with less
resistance to produce a more uniform distention.
[0516] If sufficiently hot, the balloon probably does destroy some
potentially embolizing debris that would have been discharged were
a vulnerable or unstable plaque (see Maseri, A. and Fuster, V.
2003. "Is There a Vulnerable Plaque?," Circulation
107(16):2068-2071) to rupture; however, the plaque is mostly just
crushed against the lumen wall (see, for example, Algowhary, M.,
Matsumura, A., Hashimoto, Y., and Isobe, M. 2006. "Poststenting
Axial Redistribution of Atherosclerotic Plaque into the Reference
Segments and Lumen Reduction at the Stent Edge: A Volumetric
Intravascular Ultrasound Study," International Heart Journal 47(2):
159-171; American Journal of Cardiology 89(4):368-371; Hong, M. K.,
Park, S. W., Lee, C. W., Kim, Y. H., Song J. M., and 4 others 2002.
"Relation Between Residual Plaque Burden after Stenting and
Six-month Angiographic Restenosis," Honda, Y., Yock, P. G., and
Fitzgerald, P. J. 1999. "Impact of Residual Plaque Burden on
Clinical Outcomes of Coronary Interventions," Catheterization and
Cardiovascular Interventions 46(3):265-276; Alfonso, F., Garcia,
P., Pimentel, G., Hernandez, R., Sabate, M., Escaned, J., Banuelos,
C., Fernandez, C., and Macaya, C. 2003. "Predictors and
Implications of Residual Plaque Burden after Coronary Stenting: An
Intravascular Ultrasound Study," American Heart Journal
145(2):254-261).
[0517] The failure to actually remove plaque not only impairs
healing, exacerbates the disease, and promotes restenosis, but can
result in the prolapse of residual tissue through the stent struts,
as addressed below in the section entitled Basic Strengths and
Weaknesses of Prior Art Stenting in Vascular, Tracheobronchial,
Gastrointestinal, and Urological Interventions, among others. When
the plaque and subjacent tissue are too hard to be smashed or
reduced, the balloon accomplishes luminal dilation by tearing
circumferential fibers. This is often the basis for the stretching
injury which results in endothelial dysfunction and induces the
intimal (endangial) and medial hypoplasia that ensue.
[0518] The means to be described removes plaque through cutting,
abrasion, thermoplasty, cryoplasty, or any combination of these.
Theremoplasty, for example, is routinely used to destroy
potentially embolizing debris that might be discharged by the
rupture of erodable fibrous, vulnerable, or unstable plaque by the
passing muzzle-head. In Barrel-assemblies which incorporate
fluidically operated radial projection units, addressed below in
the section entitled Radial Projection Units, cryoplasty, believed
to retard intimal (internal lining, Bichat's tunic) hyperplasia, is
also available. Where disease is extensive, thermoplasty is used as
a precaution over the entire length of the artery, usually not as a
preliminary procedure but just in advance of implant discharge.
[0519] When the application of any of these ablative or angioplasty
means to include heat, cold, abrasion, and cutting or shaving is
continuous over a significant length of the lumen, the speed of
travel, or rate of transluminal advancement of the muzzle-head over
the internal surface of the ductus, is set for the prescribed time
of exposure for the diagnosis. Cryoplasty, for example, is
performed at minus 10 degrees centigrade for 20 seconds. Executing
a tightly controlled rate of travel, hence, time of exposure is
usually entrusted to a variable speed linear positioning stage.
Off-pump use in the coronaries and use in the carotids especially
demands a muzzle-head that least interferes with perfusion. Despite
the features incorporated into the muzzle-head to minimize
obstruction summarized below in the section entitled Hypoxia and
Ischemia-averting Elements, a muzzle-head of a diameter suitable
for use in a peripheral artery of the same diameter would be too
large.
[0520] At the same time, minimizing procedural duration and
achieving uniformity of implant placement are all the more
important in these arteries, making the use of multibarrel-tube
barrel-assemblies, which must be larger in diameter, under
automatic machine control desirable. Vasodilators can be used to
reduce the limitation on gauge of the muzzle-head and minimize if
not eliminate the need for extracorporeal oxygenation. The
concurrent use of nonvasodilating (nonantgiotensive,
nonvasotensive) inotropic medication to increase the force of the
heart contraction without interfering with the vasodilation is
additionally helpful. When the degree of dilation sought is
greater, more extended in length, and more demanding in terms of
speed, the medication is administered by infusion.
[0521] Otherwise, the muzzle-head can itself be used to deliver
medication as it approaches, the rate of advancement adjusted to
accommodate the medication response time. Vasospasm reflexive to
the presence of the muzzle-head, for example, should it arise, is
prevented through the site specific release of antispasmodic or
spasmolytic drugs. Ordinarily through an open-ended service
catheter to preserve use of the barrel-tube for miniball discharge
or ballistic implantation, the muzzle-head could be used to deliver
liver metabolism nondependent vasodilators highly localized to the
treatment site, such as adenosine, nitrates (nitroglycerin,
nitroprusside, isosorbide mono or dinitrate), mannitol, hydralazine
hydrochloride, nicardipine, nesiritide, nimodipine, verapamil,
milrinone, trimethaphan, fasudil, and colforsin daropate, as well
as platelet blockade or heparin, for example.
[0522] Application thus can be accomplished in any of several ways,
to include ejection by ejection tool-inserts, injection by
injection tool-inserts, and ejection by open or injection by
hypotube-ended service catheter syringes, all to be addressed.
Prepositioned impasse-jackets whether used to prepare a segment of
a ductus for discharge implantation in advance in the manner
addressed in the sections below entitled Concept of the
Impasse-jacket and Miniball and Ferrojluid-borne
Particle-impassable jackets, or Impasse-jackets, do not interfere
with the use of a barrel-assembly. With the availability in the
form of impasse-jacket held miniballs of a counteractant or
reversal, that is, neutralizing or scavenging agent, such as
mannitol dehydrogenase or mannitol 2-dehydrogenase, the localized
(nonsystemic, targeted) application of mannitol, for example, can
be delivered at a high dose as localized that is systemically
minute.
[0523] Delivered peripherally or otherwise distant from the
coronary arteries, mannitol, for example, can be administered to
patients with advanced coronary disease, if distant from the heart,
to those with heart failure, if distant from the kidneys, to those
with renal insufficiency, and if distant from the lungs, to those
with pulmonary vascular congestion, (see, for example, The Merck
Manual of Diagnosis and Therapy, 18th Edition, 2006, page 2578),
while avoiding unwanted side-effects such as diarrhea (Merck
Manual, pages 78 and 84), gastric upset (nausea, vomiting),
diuresis, for which the dose of mannitol as a dehydrating agent and
osmotic diuretic must be larger, headache, confusion,
hyperglycemia, and allergic reactions, among others. Unlike a
radially symmetrical balloon, the muzzle-head, which is contrast
marked to assist in its orientation, can be used to treat radially
asymmetrical, or eccentric, lesions in a discretionary manner
provided these can be clearly seen.
[0524] Impasse-jackets can suspend drug carrier nanoparticles in a
ferrofluid or medication miniballs, to include those comprising
`smart pills,` in the lumen that will release medication only when
signaled or stimulated to do so from outside the body. The jacket
is then reloaded as necessary. Self-reloading of the
impasse-jacket, magnetized miniballs, stays, arrays thereof,
patch-magnet, or magnet-jacket of a drug carrier nanoparticulate or
miniballs outside the clinic to reach a level along the
gastrointestinal tract is by ingestion, with a followup triggering
substance administered likewise as needed. Magnetically susceptible
nanoparticle-bound drugs that can be ingested to pass through the
gut and liver and into the bloodstream are under development.
Secondary triggering as needed or prescribed makes it possible for
the patient to initiate the release of a prepositioned drug outside
the clinic preferably by ingesting or otherwise injecting a
triggering substance or solvent and/or by applying heat at the
treatment site for example.
[0525] Delivery to the trachea and bronchi is by inhalation of the
nanoparticulate-bound drug as a metered dose inhaler-delivered
aerosol. Charging and triggering along the vascular tree are
preferably by ingestion, or if necessary, by injection or
subcutaneously implanted access portals (ports, portacaths) or
peripherally entered central catheters (The Merck Manual of
Diagnosis and Therapy, page 1161), these latter also suited to
allow direct access to urinogenital (urogenital, genitourinary)
ductus. Recharging and triggering are addressed below in the
sections entitled System Implant Magnetic Drug and Radiation
Targeting and Cooperative Use of Impasse-jackets in Pairs and
Gradient Arrays, among others.
[0526] Unlike the implantation of spherules (miniature balls,
miniballs), stays, or implants in the form of tiny arcuate bands,
are nonballistically inserted into the wall of the ductus from the
outside by means of a special hand tool to be described. When the
ductus to receive the implants is already exposed or can be
accessed with trauma justified within the medical context, a hand
tool is used to implant the stay or stays through an incision
little more than microscopic in length. Existing means for
delivering drugs ballistically are not endoluminal (see, for
example, Kendall, M. A. 2010. "Needle-free Vaccine Injection,"
Handbook of Experimental Pharmacology(197):193-219; Liu, Y. 2007.
"Impact Studies of High-speed Micro-particles Following Biolistic
Delivery," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Engineering. 54(8):1507-1513; Kendall,
M., Mitchell, T., and Wrighton-Smith, P. 2004. "Intradermal
Ballistic Delivery of Micro-particles into Excised Human Skin for
Pharmaceutical Applications," Journal of Biomechanics
37(11):1733-1741), which distinction is critical for the treatment
of disease affecting any tubular structure (see, for example,
Kendall, M., Mitchell, T., and Wrighton-Smith, P. 2004, Op
cit.).
[0527] The terms ballistic or biolistic in relation to gene
alteration and treatments with gene guns and the delivery of drugs
through the skin are thus unrelated to the content herein. An
extraluminal stent leaves the lumen free and clear of any foreign
object and is substantially compliant with the functional changes
in gauge of the ductus. It therefore less alters flow-through, does
not contact, much less chronically irritate the lumen lining, and
less interferes with subsidence in inflammation and healing.
Avoiding the implantation of a foreign object within the lumen and
interference with the expansion, contraction, and flexion of the
ductus is critical for accommodating normal physiology while
maintaining patency. The citation of drugs herein is for the
purpose of suggesting applications related to the apparatus
described and not an endorsement or recommendation.
[0528] Veterinary drugs are regulated by the Department of
Agriculture Center for Veterinary Biologics, or the Food and Drug
Administration Center for Veterinary Medicine, and may not undergo
multiple extensive clinical trials; as is applied to drugs for use
in man, drug testing results obtained with animals is tentative.
While the propulsive force specified herein is supplied as in most
airguns by pressurized gas, such as compressed air or carbon
dioxide (CO.sub.2) delivered from a cylinder (which may be referred
to as a tank, canister, powerlet, pistolet, capsule, or cartridge),
alternative propulsive means, such as a spring-piston or an
internal air column that is pressurized by a hand pump as in
pneumatic airguns could be similarly applied. Some stents can
release medication as they disintegrate. Whether this effects a
cure depends upon the lesion and the patient. With the exception
that stents which release medication and/or radiation have the
potential to effect a cure, to the extent they are mechanical
scaffolds, stents are nosotropic or symptomatically corrective
through mechanical means, not etiotropic or curative.
[0529] No claim beyond this is made for any of the means to be
described. However, patency is always essential to sustain function
and life, making the capability to do so with fewer sequelae over a
long period important. Stenting does not supplant but complements
concurrent medical management; the decision to insert a stent to
maintain luminal patency in cases of bronchiectasis, for example,
will depend upon the variable symptoms of specific patients.
Moreover, noninvasive management cannot duplicate the remedial
effect of a stent, is seldom any more able to effect a cure, and
always carries the risk of side effects. The apparatus to be
described targets medication at or into the lesion, minimizing the
dose and promoting local uptake thus avoiding the circulation, and
is able to apply various therapeutic treaments as well as introduce
the intraductal component of an extraluminal stent.
[0530] While never used in extraluminal stents, magnets have been
used intracorporeally to induce compression necrosis, anastomosis,
and other purposes for decades and continues in use (see, for
example, Jansen, A., Keeman, J. N., Davies, G. A., and Klopper, P.
J. 1980. "Early Experiences with Magnetic Rings in Resection of the
Distal Colon," Netherlands Journal of Surgery 32(1):20-27; Cope, C.
1995. "Creation of Compression Gastroenterostomy by Means of the
Oral, Percutaneous, or Surgical Introduction of Magnets:
Feasibility Study in Swine," Journal of Vascular and Interventional
Radiology 6(4):539-545; Yamanouchi, E., Kawaguchi, H., Endo, I.,
and Arakawa, H., Yamaguchi, T., Sakuyama, K, et al. 1998. "A New
Interventional Method: Magnetic Compression Anastomosis with
Rare-earth Magnets," Cardiovascular and Interventional Radiology
21(Supplement1):S155; Okajima, H., Okajima, H., Kotera, A.,
Takeichi, T., Ueno, M., Ishiko, T., and 4 others 2005. "Magnet
Compression Anastomosis for Bile Duct Stenosis after Duct-to-duct
Biliary Reconstruction in Living Donor Liver Transplantation,"
Liver Transplantation 11(4):473-475; Kaidar-Person, O., Rosenthal,
R. J., Wexner, S. D., Szomstein, S., and Person, B. 2008.
"Compression Anastomosis: History and Clinical Considerations,"
American Journal of Surgery 195(6):818-826; Jamshidi, R.,
Stephenson, J. T., Clay, J. G., Pichakron, K. O., and Harrison, M.
R. 2009. "Magnamosis: Magnetic Compression Anastomosis with
Comparison to Suture and Staple Techniques," Journal of Pediatric
Surgery 44(1):222-228; Jang, S. I., Kim, J. H., Won, J. Y., Lee, K.
H., and 4 others 2011. "Magnetic Compression Anastomosis is Useful
in Biliary Anastomotic Strictures after Living Donor Liver
Transplantation," Gastrointestinal Endoscopy 74(5):1040-1048).
3. Terminology
[0531] `Proximal` and `distal` are used in relation to the
operator, not the treatment site. `Vessel,` `vas,` `ductus,` and
`conduit` all denote tubular anatomical structures, but `vessel` is
generally understood and is used here to refer to blood vessels
rather than to other kinds of vessels. Terms derived from `vessel,`
such as `intravascular,` extravascular,' `intravasated,` and
`extravasated` pertain to blood vessels. `Ductus` is used to refer
to any kind of tubular structure and not just a duct leading away
from a gland, for example, and the terms `intraductal` and
`extraductal` are used with respect to any type ductus. `Miniball`
as used herein refers to millimetric range spherules for
implantation to treat disease with no relation to ammunition.
[0532] The term `base-tube` denotes a platform for magnets;
nonplatform jackets such as intrinsically susceptible to magnetic
tractive force are not base-tubes but stent-jackets in themselves.
Where greater tractive force is required to draw the susceptible
matter into the wall of the ductus, either type jacket can be used.
The context will make it plain whether use of the term `flow
reversal` pertains to a. Carotid angioplasty and stenting,
addressed below in section VII2j(1) entitled Incorporation of
Adscititious Capabilities into Barrel-assemblies, b. Aortic
regurgitation on the diastoles due to aortic valve impairment, or
c. Switching from outflow, ejection, or irrigation to inflow or
aspiration in the use tool-inserts, addressed below in section
VII2g(3)(e)(vi), entitled Fluid-operated Tool-inserts, to Include
Ejector-irrigator-aspirators and Injectors.
[0533] Terms pertaining to detailed parts of components are
presented in the respective section describing the component and
not anticipated. The superior thoracic aperture is the thoracic
inlet of the anatomist and thoracic outlet of the clinician.
Reference herein to the thoracic inlet is to designate this axial
level in a dog or other quadruped with tracheal collapse. The term
`propulsive force` applies to the momentum imparted to a miniball
by the gas pressure that drives it forward through the
barrel-assembly and to the force imparted to a bolus advanced
through the digestive tract, the context making which meaning
pertains clear. `Thermoplastic` and `thermoplasty` pertain to
thermal angioplasty, not viscosity, hardness, or cosmetic surgery.
Consistent therewith, while any tubular anatomical structure may be
referred to as a vas or ductus, the term `endovascular,` for
example, because it is derived from `vascular,` implies limitation
to an arterial or a venous stent and is therefore avoided.
[0534] When used as an anatomical term, the plural for ductus is
ductus (pronounced ducktoose, not "ducti)." An implant placed
within the wall of a ductus is in the ductus but not within the
lumen of the ductus, which distinction is here significant. `Wider`
is short for larger in diameter, and `narrower` for smaller in
diameter, gauge, or caliber. `Hypoxia` is used to denote an
insufficiency of oxygen due to obstruction whether caused by
intrinsic endoluminal deformation or by apparatus in the airway or
the bloodstream, whereas `ischemia` refers only to obstruction of
the blood supply.
[0535] As used herein, the term `implant` denotes solid objects or
pre-solid infusions or injections that aggregate together and cure
to become solid or semisolid objects introduced and/or positioned
using means set forth herein. Such placement is either within the
wall surrounding a lumen or other tissue, or is in surrounding, or
periductal, relation to the native tubular anatomical structure or
condit, as is the case with stent- and impasse-jackets. Unless
absorbable, implants are to remain inside the body following
placement. Nonperiductal, or intralmural, implants consist of
medication and/or magnetically susceptible matter in the relative
proportion optimal for the site of treatment. In this context,
optimization comprises structural correction, medical remediation,
and the inclusion of only so much magnetically susceptible content
as is necessary to assure implant retractability or recoverability
should the need arise.
[0536] Not referred to as `implants` are tools used to place
implants, to include stay insertion devices, barrel-assemblies, and
combination form barrel-assemblies. The lack of prior art for
methods and means of treatment directed toward the placement of
implants within the walls of ductus is reflected in an inadequacy
of established terms. `Endoluminal,` indicates that the referent
(usually a stent) is not simply intraductal but within the lumen;
when dealing with extraluminal stents, which include a collective
or distributed intraductal component which is extraluminal as
situated within the lumen wall but otherwise external to the ductus
as consisting of a circumvascular component, the term `endoluminal`
serves to distinguish prior art stents from the extraluminal stents
described herein.
[0537] Except in using the standard term `intraductal
brachytherapy,` intraductar is used to mean within the wall of the
ductus, not passed through its lumen. Because the recognized terms
`intraductal,` `intratubal,` `intraluminal,` or applying the term
more generally than to the subarachnoid or subdural spaces,
`intrathecal,` do not distinguish `within a ductus from `within the
lumen of the ductus, here the more recently recognized (included in
medical dictionaries) but long commonly used and immediately
understood terms `endoluminal` and `extraluminal` are used. The
term `intraluminal` had already been accepted, but its complement,
`extraluminal,` had not.
[0538] The term `endoluminal` is not widely recognized as combining
a Greek prefix with a Latin stem word or root, but the term
`endovascular (endoluminal vascular),` of like composition, has
more recently been accepted through common use as necessary and
obvious in meaning. Suture loops, or suture eyelets, are small
optional handles integral with the stent-jacket for passing through
suture in order to stabilize the stent-jacket in position by
attachment to neighboring tissue in locations where pronounced
vasotonic, peristaltic, or bodily movement might otherwise cause
the stent-jacket to become displaced, or migrate. End-ties are
suture, usually prefastened to the stent-jacket, either with rivets
or through suture loops or suture eyelets for wrapping about the
ends of a stent-jacket to the substrate ductus beyond the end
margins to fix the stent-jacket in position.
[0539] `Endomural` and `endoparietal` likewise combine a Greek
prefix with Latin suffixes, and are not conventionally applied to
ductus, so that an implant within the wall of a ductus is left to
be `intramural` or `intraparietal,` the conventional pertinence to
a wall surrounding a cavity forgone. The recognized term
`endoprosthesis` and unrecognized term `endostent` as a contraction
for endovascular or endoluminal, stent to denote a conventional or
intraluminal stent, can be used for brevity; however, since an
extraluminal stent of the kind to be described herein is not
entirely extraductal, the contractions `extrastent` and `exostent`
are rejected as misleading in addition to lacking acceptance.
[0540] An `extraluminal` stent consists of subadventitial
(perimedial) or medial, hence, intraductal but extraluminal
spherule implants, and an extraductal, specifically circumductal or
periductal, a fortiori, extraluminal, stent-jacket, magnet-jacket
(magnet-wrap), or otherwise, subcutaneous or suprapleural
clasp-magnets. The term "external stent" as previously used applies
to various cuffs and sheaths that in application, structure, and
function are fundamentally different from the extraluminal stents
to be described herein. A ductus is effectively `stented` whether
the extraluminal intraductal component consists of ferromagnetic
miniballs, stays, a clasp-jacket, or a combination of these, and
whether the extraductal component consists of a periductal
(circumductal) stent-jacket, more remotely placed patch-magnets,
magnet-wraps, or a combination of these.
[0541] `Abluminar` means `more distant from the ductus or its
central axis. Inside the lumen, `abluminal` means farther from the
longitudinal central axis, hence, closer to the lumen wall, whereas
outside the ductus, `abluminal` means farther from the lumen wall.
`Adluminal` `means the opposite--closer to the ductus or to its
central axis; outside the ductus, `adluminal` means closer to the
lumen wall or outer tunic, and within the lumen, away from the
lumen wall or inner tunic and toward the lumen axis. `Luminal`
means of or about the lumen; `adluminal,` never "luminal" used
herein to denote closer to the central axis of the lumen. These
terms are purely directional, hence, nonspecific as to the layer,
depth, or distance.
[0542] The terms `circumluminal` and `periluminal` are neither
recognized nor clear in distinguishing whether the surrounding is
of or along the internal surface of the lumen, within the wall
about the lumen, or about the ductus as a whole. The term
`subadventitial` as used herein denotes the depth into the lumen
wall at which the material of the wall becomes the peripheral
connective tissue comprised of the external elastic lamina (lamina
elastica externa) just outside of the smooth muscle and inside the
tunica adventitia or outer fibrous jacket. `Ferromagnetic` denotes
drawn to a magnet, or magnetizable. The term `magnetized` denotes
intrinsic magnetization or provided with magnets.
[0543] A barrel-assembly uses a narrow pliant catheter to extend
the muzzle of an airgun forward or distad allowing transluminal
passage and endoluminal discharge. Since the effective muzzle is no
longer that of the airgun, the term `muzzle-head` is used to denote
the displaced or effective muzzle, `exit port` or `exit-hole` to
denote the aperture of projectile release, and `exit velocity` used
in lieu of muzzle velocity. The term `bore` is not literally
applicable to the internal diameter of a barrel-tube, which is an
extrusion, but is nevertheless useful to denote the lumen or
diameter (gauge, caliber) thereof `Port` and `portal` refer to the
entry incision or wound, not a sleeve inserted to expedite passage
therethrough. While no guidewire is used, the terms `steerability`
and `trackability` are used to denote the same attributes in
relation to a barrel-assembly or radial projection catheter.
[0544] `Torqueability` denotes the resistance of a catheter to
twisting or helical deformation when rotated at the manipulated or
proximal end. Parenthetically, in the present context, when the
need for steerability outweighs the need for torqueability, the
pliancy required results in a loss of torqueability, necessitating
the incorporation of a hard-wire remotely controlled electrical
motor to rotate the distal muzzle-head of the barrel-assembly.
`Injectant` is used to refer to any substance to be injected--not
just an allergen. The term `orthosis` suggestive of artificial
limbs, the term `prosthesis` is used to denote a device that does
not necessarily replace, but rather augments or supports a part
that failed due to disease, such use conventional. `Thermal-window`
and `heat-window` denote a temperature changing window whether used
for heating or chilling.
[0545] Most often the term `heat-window` will refer to a heat
conduction plate overlying an electrical winding used as the heat
source. The term `ablation` as conventionally used is not limited
to the removal of tissue by means of cutting, and here, consistent
therewith, denotes the destruction of tissue protrusive into a
lumen whether by means of thermal (thermocautery) or cryogenic
cautery (cryocautery) or by cutting (shaving) or abrasive action.
The term "barrel" as denoting a cylindrical form or cylindrically
formed part of a larger structure is in standard use relative to
guns, eyelets, rivets, syringes, springs, and plating equipment,
all directly involved herein, the context making it clear which of
these meanings is intended.
[0546] Most often the term `barrel` will pertain to that of a
commericial airgun or the primary vertical member in a control
syringe-type stay insertion tool. Exceptionally, the `barrel` in an
ejection or injection tool-insert refers to function as a piston or
plunger receiving component, regardless of cross section, which can
be other than circular. The term `barrel-catheter` as used herein,
if not unique, is believed to have little prior use, but the term
`barrel-assembly` is commonly used with respect to firearms,
extruders, hydraulic pistons, microscopes, syringes, door curtain
supports, and many other devices not related to the apparatus to be
described.
[0547] Depending upon the context, `clip` denotes a magazine clip
used to load spherule implants in an interventional airgun for
discharge, strips of stays for loading into and sequential ejection
from a stay insertion tool in a manner analogous to office staples,
or spring clips for fastening attachments alongside a stay
insertion tool, all to be described. Even though clasp-magnets and
clasp-wraps attach to tissue with clasps or prongs, these are not
referred to as `clips.` The term `magazine` used alone likewise
refers to a container for a load of projectible implants queued for
discharge from an airgun or a stay insertion tool. The term
`eccentric` with respect to vascular lesions denotes radially
asymmetrical, and with respect to the axle in a miniature fluid
damper-valve to be described, off-center.
[0548] `Impasse-jacket` denotes an impasse-jacket with any
associated dummy collars or outriggers. An `airgun` or `air gun`
discharges implants as projectiles; a vortex tube-based cooling and
heating device is referred to by the standard industrial term `cold
air gun.` `Applicator` herein refers to a syringe, such as one used
to dispense a surgical cement or tissue sealant as a whole and not
just the nozzle, outlet tube, or `tip` thereof, nor a separate
spatula or brush for spreading a cement, or to a tool-insert type
syringe, as will be described. The traditional meaning of
`percutaneous` as passing through without breaking the skin
(transcutaneous; transdermic; diadermic) is no longer restricted in
meaning thus, the very term `percutaneous transluminal coronary
angioplasty` for procedures that require entry by incision and
arteriotomy making the point.
[0549] The unrecognized terms `permural` and `perparial` are
commonly used to refer to the walls of body cavities and organs but
not the walls of ductus. `Parietal` as it pertains, for example, to
cells of the stomach lining, (parietal cells, acid cells, oxyntic
cells) is used to refer to the lining of a ductus when an
outpocketing of a cavity, such as the inside of the stomach, but
not the vascular endothelium or intima. The term
`ductus-intramural` is used herein to denote a position within the
wall about a lumen. Until changed by adjustment of the controller
(indexer) or changing the step mode at the driver (amplifier), a
stepper motor rotates by a consistent angle as would move or
`increment` a linear positioning table (linear positioning stage)
by the equivalent constant linear distance, here along the lumen of
a ductus.
[0550] To distinguish between these `increments` as elementary
rotatory steps set by the step-angle from the overall segment or
distance along the lumen traversed as the sum of these elementary
steps, the term `step` is limited to the action of the stepper
motor, and the term `increment` applied to the transluminal segment
traversed as the sum of these steps. The term `torquer` is used to
describe both a kind of electrical motor and knobs used to rotate
catheters, the term `cure` used for the setting time of an adhesive
and the time to heal, the context making it clear which of these
meanings is intended. The specification of a stepper motor as
linear stage driver is based upon the prevalence of such
application and not to be taken in a limiting sense. `Atherectomy`
denotes a form of angioplasty that unlike the compression of plaque
by a balloon, cuts the plaque away.
[0551] Thermal and laser catheters actually remove (ablate,
atherectomize) rather than merely crush plaque or effect luminal
distention by tearing circumferential fibers, but cutting as
suggested by the suffix -`ectomy` is uninvolved, so that these
methods are usually referred to as forms of angioplasty. The
angioplasty-capable barrel-assemblies and radial projection
catheters to be described can eliminate plaque by different means,
to include cutting action with radial projection unit tool-inserts,
which constitutes a form of atherectomy literally understood, but
also by thermal, cryogenic, or laser action, for example, which are
more accurately referred to as types of angioplasty. Since the term
`angioplasty` is applied to atherectomy but the reverse is not
true, the one term that covers both actions of a barrel-assembly
used as an independent plaque-removal device is `angioplasty,`
prompting the term `angioplasty-capable barrel-assembly` or
`angioplasty barrel-assembly.`
[0552] The term `cavitation` in engineering denotes the generation
of bubbles in a fluid medium, whereas in medical use, the same term
denotes the formation of vacuities, vacuoles, or cavities whether
normal or pathological. The term `sweep,` as in `side-sweeper,` is
used to mean to pass over, to sweep past or across, whether with a
hot gas, fluid medication, a shaving or an abrading head, only the
last of these applying a brushing action and not necessarily using
bristles. The term `recovery` applied to electromagnets denotes
applicability to retrieve dropped (intravasated, escaped) or
extract mispositioned miniballs or stays, sparing all of `recovery
and extraction miniball electromagnet assembly.`
[0553] Whereas the electronic components in positional control
systems were once separate and distinct, miniaturization has led to
miniaturized combinations of these that obscure the functional
distinctness of each component. These include a manually operated
positional command (set point, zero point) input device, or
control, such as a digital encoder or an analogue (resolver or
synchro), a programmed motion instruction director or controller, a
differential (comparator), servomotor (actuator), machine table,
shaft, or other driven member, and output or positional difference
(displacement) measuring device, usually of the same kind as the
command input device, that provides the signal fed back to the
differential.
[0554] This combination and integration has resulted in much
confused terminology, such as use of the term `amplifier,` normally
synonymous with `driver,` to denote an apparatus that actually
includes the control or controller. Herein, the terms `controller`
or `servocontroller` denote the set point positional director or
controller, and the other terms are specific, so that `amplifier`
or `servoamplifier` denotes the amplifier, `differential` the
differential, and so on. The simplest barrel-assemblies consist of
only a ballistic component. More advanced barrel-assemblies add
components inside of, that is, centrally or medially to, and/or
outside of, that is, peripherally to, the ballistic component. The
ballistic component consists of the barrel-tube or tubes, one or
more recovery tractive electromagnets, and in barrel-assemblies for
use in the bloodstream, gas pressure relief or diversion
channels.
[0555] In a radial projection catheter, which specifically lacks a
ballistic component, there are only inner and outer components.
When more than one barrel-tube is present, the gas pressure
diversion channel is usually shared by and positioned between or
amid the barrel-tubes. While central and referred to as the central
canal, it is not a central component but rather part of the
ballistic component. To allow for the incorporation of a central
component, the gas pressure diversion channel is divided as to be
respective of each barrel-tube, displacing these ballistic
components peripherally, as seen in an edge-discharge
barrel-assembly. When displaced peripherally thus, a single central
gas pressure diversion channel, or central canal, is no longer
present.
[0556] A central component is a commercial device, such as a laser
or atherectomy cutting tool, to which is applied the least
modification that will allow it to be incorporated into the
ballistic catheter, or barrel-assembly. A barrel-asembly that
includes a central channel for a permanent central component or
interchageable central components is a combination-form
barrel-assembly, the central component occupying the central
channel, passage, or passageway. Combination-form barrel-assemblies
include central and ballistic components, and unless omitted to
allow additional cross sectional area for these, a peripheral
component. Thus, only a combination-form barrel-assembly can
include a central, and therewith, all three components. A
peripheral component consists of radial projection units, which
belong to one or more circuits electrical and/or fluidic.
[0557] The term `fluidic` herein is applied not only to a fluid
circuit but to components that are inserted into a fluid line. When
the ballistic component is omitted, the apparatus is not a
barrel-assembly but a specialized radial projection catheter and
the terms central, ballistic, and peripheral do not apply.
Structurally isolated from other components, such is no longer a
component or peripheral. However, if a central component in the
form of a laser, thrombectomizer, or atherectomizer, for example is
incorporated into a radial projection catheter, central and
peripheral components are included in a catheteric device which is
not a barrel-assembly. `Stereotactic` or `stereotaxic` denotes the
precise positioning of a removal path for a miniball to be
relocated or removed through the use of three-dimensional
coordinates, suitable imaging machine, contrast dye, and a powerful
extracorporeal electromagnet.
[0558] Such extended use to parts of the body other than the brain
appears in use of the term `stereotactic mammography,` for example.
A ballistic catheter includes only the ballistic component, making
terms pertaining to relative position among components
inapplicable. A ballistic catheter can be a simple pipe or a radial
discharge barrel-assembly, which consists of a barrel-tube or tubes
jacketed about to avoid injury to narrow ductus. Simple pipes and
radial discharge barrel-assemblies with a single barrel-tube are
monobarrels. Radial discharge monobarrels and multibarrels for use
in the bloodstream include one or more gas pressure diversion
channels. Since the jacket and gas diversion channels are parts of
the ballistic component, a basic radial discharge barrel-assembly,
even when a multibarrel, includes only a ballistic component.
[0559] `Gas-operated` in the present context denotes only that
pressurized gas rather than a spring mechanism, for example, is
used to propel the miniball implants, and not that the exhaust gas
of the preceding discharge is used to chamber the next miniball as
in the blowback operation of a firearm. Use of the term `discharge`
to denote actions so different as the sudden expulsion of miniballs
and the relatively quiescent release of substances from syringes
accords with convention. The terms `aspiration` and
`microaspiration` as used herein denote and are consistent with the
processes used to study embryos, for example, and not factors in
pulmonary or airway disease.
[0560] Miniball-impassable jackets, or magnetized impasse-jackets,
are singular or simple; simple-extended or braced when effectively
elongated for positional stability through the addition of
unmagnetized dummy-collars fastened by rigid bridging arms at
either or both ends; compound when two magnetized jackets are
included, or chained when including more than two, such latter
triple, quadruple, and so on. Since the addition of dummy-collars
imparts both stabilizing elongation and multipartedness, braced
jackets are technically compound and compound jackets `braced;`
however, it being superfluous, compound impasse-jackets are not
referred to as braced nor braced jackets as compound.
[0561] `Chain` jackets refers to impasse-jackets that include more
than two dummy-collars and `compound` jackets that include two or
more constituent jackets. `Composite` or `mixed` refers to compound
or chain jackets in which one or more of the constituent jackets is
used to trap any passing miniball, that is, as a `trap-jacket,`
while one or more is used to retain a radiation or drug-releasing
miniball or miniballs at a certain level in the lumen as a `holding
jacket.` `Gastrointestinal` as used herein refers to the entire
digestive tract inferior to the cricoid cartilage, and not just the
stomach and intestines as the literal meaning would suggest.
4. Concept of the Ductus-Intramural Implant
[0562] The four methods for placing magnetically susceptible
implants within the wall surrounding the lumen of a tubular
anatomical structure (conduit, ductus, vas, vessel) are specified
below in section XXII, entitled Glossary of Terms. Clotting,
problem bleeding following the administration of anticlotting
drugs, and accidental intraysation or the entry of a miniball into
the circulation are addressed in several sections. Provided the
protective measures indicated are employed, these potential
deterrents will be kept to a minimum if not eliminated and should
pose no greater hazard than do existing standard of care
measures.
[0563] Miniballs and stays can be placed in a preliminary procedure
and allowed to become integrated into, that is, infiltrated or
ingrown by and adherent to the surrounding tissue; over an
interval, the use of tissue binding agents and cellular
proliferation-accelerating substances applied when the need for
stenting is urgent. Since stays used to stent are introduced
through the same small access portal (keyhole incision,
laparascopic entry wound) as is the stent-jacket, to place both
during a single procedure is preferred. When necessary, however,
the incision is left to heal by tertiary intention or delayed
primary closure, thus preserving access without the need for
reincision to introduce the stent-jacket at a later date.
[0564] Local subcutaneous injection of methylprednisolone acetate
(Depo-Medrol.RTM. Pfizer) synthetic glucocorticosteoid can be used
to further retard union, oral retinoids (Wicke, C., Halliday, B.,
Allen, D., Roche, N. S., Scheuenstuhl, H., Spencer, M. M., Roberts,
A. B., and Hunt, T. K. 2000. "Effects of Steroids and Retinoids on
Wound Healing," Archives of Surgery 135(11):1265-1270) and/or
possibly the infusion of IGF-I into the wound chamber (Suh, D. Y.,
Hunt, T. K., and Spencer, E. M. 1992. "Insulin-like Growth Factor-I
Reverses the Impairment of Wound Healing Induced by Corticosteroids
in Rats," Endocrinology 131(5):2399-2403) used to reverse the
effect if necessary. Properly used and disinfected, the risk of
infection is slight even if months pass until the stent-jacket is
inserted.
[0565] 4a. Tissue Acceptance of Ductus-Intramural Implants
[0566] 4a(1). Significance of Sterile Antixenic Immune Tissue
Reaction
[0567] An adverse or allergic tissue reaction that is not temporary
will result in implantation failure, making materials testing
critical. Ductus-intramural implants include miniballs and stays.
The immune response to sterile implants is not confined to
individual hypersensitivity or allergic reactions to certain
proteins but can occur upon introduction of any implant into the
body as foreign (see, for example, Malik, A. F., Hogue, R., Ouyang,
X., Ghani, A., Hong, E., and 8 others 2011. "Inflammasome
Components Asc and Caspase-1 Mediate Biomaterial-induced
Inflammation and Foreign Body Response," Proceeding of the National
Academy of Sciences of the United States of America 108(50):
20095-20100; Anderson, J. M., Rodriguez, A., and Chang, D. T. 2008.
"Foreign Body Reaction to Biomaterials," Seminars in Immunology
20(2):86-100; Wilson, C. J., Clegg, R. E., Leavesley, D. I., and
Pearcy, M. J. 2005. "Mediation of Biomaterial-cell Interactions by
Adsorbed Proteins: A Review," Tissue Engineering 11(1-2):1-18; Hu,
W-J., Eaton, J. W., Ugarova, T. P., and Tang, L. 2001. "Molecular
Basis of Biomaterial-mediated Foreign Body Reactions," Blood
98(4):1231-1238; Kao, W. J., Lee, D., Schense, J. C., and Hubbell,
J. A. 2001. Fibronectin Modulates Macrophage Adhesion and FBGC
Formation: The Role of RGD, PHSRN, and PRRARV Domains," Journal of
Biomedical Materials Research 55(1):79-88; Jenney, C. R. and
Anderson, J. M. 2000. "Adsorbed Serum Proteins Responsible for
Surface Dependent Human Macrophage Behavior," Journal of Biomedical
Materials Research 49(4):435-447; van der Giessen, W. J., Lincoff,
A. M., Schwartz, R. S., van Beusekom, H. M., Serruys, P. W.,
Holmes, D. R. Jr., Ellis, S. G., and Topol, E. J. 1996. "Marked
Inflammatory Sequelae to Implantation of Biodegradable and
Nonbiodegradable Polymers in Porcine Coronary Arteries,"
Circulation 94(7):1690-1697; Tang, L. and Eaton, J. W. 1995.
"Inflammatory Responses to Biomaterials," American Journal of
Clinical Pathology 103(4):466-471).
[0568] Immune system macrophage attack of implanted polyurethanes
in nonductus-intramural implants such as base-tubes and the linings
thereof is inhibited by means addressed below in the sections below
entitled Internal Environment-resistant Base-tube Polymers, Metals,
and Combinations Thereof and Materials Suitable for
Rebound-directing Double-wedge Linings. For medication implants
that will be dissipated or assmilated through dissolution,
enzymatic action, and sometimes hydrolysis and not subject to
tractive force except when any must be recovered, tissue reactions
are usually temporary and of negligible consequence. For stenting
stays, which will be subjected to mild tractive force, where a
treatment unrelated weakening condition following insertion is
anticipated, the stays are coated with a tissue hardening and
bonding agent, wetted with an adverse tissue reaction
counteractant, and time time allowed for tissue integration until
placement of the stent-jacket in a second procedure.
[0569] Counteractants are addressed below in the section entitled
Tissue Reaction Ameliorative Measures. Various means for warming
the site to accelerate the release of stay contents and uptake are
addressed herein, and keeping the site warm should accelerate
healing and tissue acceptance. The interval between placement of
the stays and placement of the stent-jacket must be sufficient to
allow tissue integration and not just acceptance and healing.
Unless deterred, a foreign body reaction to a nonabsorbable implant
can be acute and chronic, resulting in implant failure and harm to
the patient. Stenting is but one application for miniballs, which
have multiple drug, radiation, and other therapeutic agent-delivery
applications that may or may not include stenting.
[0570] All ductus-intramural implants contain sufficient
ferromagnetic content to allow retrieval should any be dropped,
mispositioned, or reauire emergency recovery. Miniballs used for
magnetic drug-targeting and/or to stent generally require more
magnetically susceptible content. While it should seldom prove
necessary, if the mass of lanthanoid needed to achieve the magnetic
susceptibility required were to demand miniballs too large for the
application, then any other space-taking agent coatings to be
delivered in other miniballs or would be introduced not as outer
layers but rather through endoluminal injection by tool-inserts, as
addressed below in the section entitled Radial Projection Unit
Tool-inserts, a coating of protein solder being an exception. Not
subsumed by stenting, implantation and miniballs should be
considered as capable of supporting stenting as but one application
therefor.
[0571] Prepositioning of the stent-jacket, addressed below in the
section entitled Circumstances Recommending the Use of a
Shield-jacket or Preplacement of the Stent-jacket, usually
restricted to the use of wide stays with greater adherent surface
than miniballs in any event, will be limited to wide stays where
healing time is extended and it is sought to avoid the long term
systemic administration of resolvent (anti-inflammatory)
medication. A coating containing microspheres of time-released
dexamethasone, for example, to defer a foreign body reaction is
valuable in allowing an interval for recovery from the immediate
trauma associated with insertion; however, a coating of implant
fibrinogin adsorption-averting serum, albumin, or
hypofibrinogenemic plasma can ameliorate if not eliminate such a
reaction (Hu, W-J., Eaton, J. W., Ugarova, T. P., and Tang, L.
2001. "Molecular Basis of Biomaterial-mediated Foreign Body
Reactions," Blood 98(4):1231-1238).
[0572] An additional measure for deterring if not eliminating a
detrimental reaction, surface modification, is applicable to the
permanent outer surface of miniballs to serve as the intravascular
component of a magnetic stent even when overlain by an absorbable
layer or layers (Nair, A., Zou, L., Bhattacharyya, D., Timmons, R.
B., Tang, L. 2008. "Species and Density of Implant Surface
Chemistry Affect the Extent of Foreign Body Reactions," Langmuir
24(5):2015-2024; Anderson, J. M. and Jones, J. A. 2007. "Phenotypic
Dichotomies in the Foreign Body Reaction," Biomaterials
28(34):5114-5120), perhaps the simplest being polishing (De
Scheerder, I., Verbeken, E., and Van Humbeeck, J. 1998. "Metallic
Surface Modification," Seminars in Interventional Cardiology
3(3-4):139-144).
[0573] The need to further defer the onset of a foreign body
reaction with systemic medication will depend upon the risk of
stent failure due to such a reaction; integration of the sterile
intraductal implants should allow a gradual toughening of the
tissue between the implant and the magnet (references at the
section entitled Stent-jacket Expansion Inserts), whereas an
application of excessive tractive force while the tissue remains
unaccepting of the implant increases the risk of pull-through or
delamination.
[0574] 4a(2). Duration, Extent, and Outcome of Sterile Tissue
Reaction
[0575] The duration, extent, and outcome of tissue reaction must be
considered over the range of variability for different individuals,
tissues, and pathology for implants with a surface of bare metal, a
protein solder doped onto a polymer scaffold, the same impregnated
with any of many different types of medication in any of a number
of different particulate conformations or combinations thereof, and
any of the foregoing with an outer coating of a given surgical
cement. Depending upon the specific application, the impact upon
the implants and any coatings of the tissue response and internal
environment over the long term must be considered (see, for
example, Kirkpatrick, C. J., Krump-Konvalinkova, V., Unger, R. E.,
Bittinger, F., Otto, M., and Peters, K. 2002. "Tissue Response and
Biomaterial Integration: The Efficacy of in Vitro Methods,"
Biomolecular Engineering 19(2-6):211-217).
[0576] Miniballs and stays that emit radiation can also be
prepared, for example, by ion surface engineering (see, for
example, Fortin, M. A., Paynter, R. W., Sarkissian, A., and
Stansfield, B. L. 2006. "Radioactive Sputter Cathodes for 32P
Plasma-based Ion Implantation," Applied Radiation and Isotopes
64(5):556-562). Implants that emit radiation superimpose upon the
foregong additional variables consisting of the numerous
differences among individuals in the reaction of different tissues
to radiation (see, for example, Li, X. A., O'Neill, M., and
Suntharalingam, M. 2005. "Improving Patient-specific Dosimetry for
Intravascular Brachytherapy," Brachytherapy 4(4):291-297; Bentzen,
S. M. and Overgaard, J. 1994. "Patient-to-Patient Variability in
the Expression of Radiation-Induced Normal Tissue Injury." Seminars
in Radiation Oncology 4(2):68-80). Variables arise when the
radiation responds to carcinoma (see, for example, Andreassen, C.
N. and Alsner, J. 2009. "Genetic Variants and Normal Tissue
Toxicity after Radiotherapy: A Systematic Review," Radiotherapy and
Oncology 92(3):299-309).
[0577] Predictive capability for individual reaction differences
not sufficiently developed (see, for example, Bentzen, S. M.,
Parliament, M., Deasy, J. O., Dicker, A., Curran, W. J., Williams,
J. P., and Rosenstein, B. S. 2010. "Biomarkers and Surrogate
Endpoints for Normal-Tissue Effects of Radiation Therapy: The
Importance of Dose-volume Effects," International Journal of
Radiation Oncology, Biology, and Physics 76(3 Supplement):S145-150;
Popanda, O., Marquardt, J. U., Chang-Claude, J., and Schmezer, P.
2009. "Genetic Variation in Normal Tissue Toxicity Induced by
Ionizing Radiation," Mutation Research 667(1-2):58-69; Williams, J.
R., Zhang, Y., Zhou, H., Russell, J., Gridley, D. S., Koch, C. J.,
and Little J. B. 2008. "Genotype-dependent Radiosensitivity:
Clonogenic Survival, Apoptosis and Cell-cycle Redistribution,"
International Journal of Radiation Oncology, Biology, and Physics
84(2):151-164; Williams, J. R., Zhang, Y., Zhou, H., Gridley, D.
S., Koch, C. J., Slater, J. M., and Little J. B. 2008. "Overview of
Radiosensitivity of Human Tumor Cells to Low-dose-rate
Irradiation.," International Journal of Radiation Oncology,
Biology, and Physics 72(3):909-917), whenever possible, preliminary
testing should be done using long established methods.
[0578] In empirical pretesting, a miniball of the kind contemplated
for use can also be implanted in superficial skeletal muscle or in
the submandibular salivary gland, which relatively superficial,
includes much smooth muscle tissue. The internal anal spincter
provides superficial smooth muscle of sufficient thickness and
continuity for testing but is adversely located from the standpoint
of risking infection. The inclusion of superparamagnetic magnetite
or maghemite nanoparticles or finely grained powder allows quick
retrieval of the test miniball. For testing, miniballs of identical
composition as the stays actually proposed are used (Sigler, M.,
Paul, T., and Grabitz, R. G. 2005. "Biocompatibility Screening in
Cardiovascular Implants," Zeitschrift fur Kardiologie
94(6):383-391).
[0579] 4a(3). Tissue Reaction Ameliorative Measures
[0580] Substances incorporated into implants or the coatings
thereof may be distinguished as either therapeutic or as intended
to counteract an adverse tissue response evoked by the implant
itself. Since the outer surface of each implant can consist of bare
metal or layers and an outer coating of substances that are
different and numerous, the duration for tissue subsidence and
accommodation or acceptance and integration will be variable. While
controlled release from the implants can extend the term over which
dexamethasone, for example, can continue to be delivered, eventual
exhaustion may require systemic administration (see, for example,
Vacanti, N. M., Cheng, H., Hill, P. S., Guerreiro, J. D., Dang, T.
T., and 5 others 2012. "Localized Delivery of Dexamethasone from
Electrospun Fibers Reduces the Foreign Body Response,"
Biomacromolecules 13(10):3031-3038; Bhardwaj, U., Sura, R.,
Papadimitrakopoulos, F., and Burgess, D. J. 2010. "PLGA/PVA
Hydrogel Composites for Long-term Inflammation Control Following S.
C. [Subcutaneous] implantation," International Journal of
Pharmaceutics 384(1-2):78-86; Patil, S. D., Papadmitrakopoulos, F.,
and Burgess, D. J. 2007. "Concurrent Delivery of Dexamethasone and
VEGF for Localized Inflammation Control and Angiogenesis," Journal
of Controlled Release 117(1):68-79; Patil, S. D.,
Papadimitrakopoulos, F., and Burgess, D. J. 2004.
"Dexamethasone-loaded Poly(lactic-co-glycolic) Acid
Microspheres/Poly(vinyl alcohol) Hydrogel Composite Coatings for
Inflammation Control," Diabetes Technology and Therpeutics 6(6):
887-897).
[0581] However, the implant itself or nearby magnetized miniballs,
stays, impasse-jackets, magnet-wraps, and patch-magnets, for
example, can attract a magnetically susceptible drug carrier bound
nanoparticlate, for example, that incorporates any of numerous
adverse tissue response counteractants from the passing blood or
other luminal contents for concentration at the area required, as
addressed below in the sections entitled Concept of the
Impasse-jacket and Cooperative Use of Impasse-jackets in Pairs and
Gradient Arrays, among others. More specifically, strongly
magnetized implants, such as magnet-wraps generally and miniballs,
stays, and impasse-jackets positioned to attract drug carrier
binding nanoparticles will attract such a counteractant whether
administered separately from or as cobound with a primary agent,
whereas stent-jackets, which must be less strongly magnetized to
avoid delamination and pull-through are initially coated with the
agent and supplemented at the sides with more strongly magnetized
miniballs or stays for this purpose.
[0582] When the ductus-intramural or intravascular component of the
extraluminal stent consists of miniballs, the outriggers are most
easily placed at the start and end of implantation discharge; when
stays, the more strongly magnetized stays are placed at the distal
and proximal sides of the other stays. When a preparatory
angioplasty or ablation can be avoided, the use of stays
exclusively allows avoiding the lumen entirely; however, if
miniball implantation follows a transluminal step, then stays are
just as easily placed to either side of the stent-jacket when it is
introduced. Broad stays afford a volume that allows these to be
coated with other reaction countering and other biological and/or
nonbiological pharmaceuticals. The outer surface of the implants
will often require a coating that incorporates multiple substances,
typically, one to avert inter or intratunical delamination, another
infection, and yet another to moderate any adverse tissue
reaction.
[0583] One solution is to incorporate substances that pure or
admixed, will not break down when one constituent, such as an outer
coating of a solid protein solder formulated to flow or denature at
a low temperature, still has a relatively high melting point (see
Bogni, S., Stumpp, O., Reinert, M., and Frenz, M. 2010. "Thermal
Model for Optimization of Vascular Laser Tissue Soldering," Journal
of Biophotonics 3(5-6):284-295). Current solders into which other
substances have been blended may still impose the risk of injury
when used to bond arteries (Bregy, A., Bogni, S., Bernau, Vajtai,
I., and 6 others 2008. "Solder Doped Polycaprolactone Scaffold
Enables Reproducible Laser Tissue Soldering," Lasers in Surgery and
Medicine 40(10):716-725). Protein solders usually consist of bovine
serum albumin containing a dye to enhance laser absorption at the
wavelength employed (see Maitz, P. K. M., Trickett, R. I. Tos, P.
Lanzetta, M. Owen, E. R., Dekker, P. Dawes, J. M., and Pipet, J. A.
2000. ""Tissue Repairs Using a Biodegradeable Laser-activated Solid
Protein Solder," IEEE Lasers and Electro-Optics Conference
Proceedings, pages 446-447; Maitz, P. K., Trickett, R. I., Dekker,
P., Tos, P., Dawes, J. M., Piper, J. A., Lanzetta, M., and Owen, E.
R. 1999. "Sutureless Microvascular Anastomoses by a Biodegradable
Laser-activated Solid Protein Solder," Plastic and Reconstructive
Surgery 104(6):1726-1731).
[0584] Any proteinaceous material that thermally denatures upon
heating can be used as a soldering agent, to include any serum
protein, such as albumin, fibronectin, Von Willebrand factor,
vitronectin, or any mixture of proteins or peptides (Gregory, K. W.
1998. "Method of Producing Biomaterials," Patent WO/1998/036707).
Any or all of these materials can evoke an adverse tissue reaction.
For cohesion and pliability, the proteinaceous material is applied
or doped onto a synthetic polymer such as glycolic
(alpha-hydroxyacetic) acid as a scaffold (backing, basement layer).
Such scaffolding will usually contain alpha-hydroxy polyesters
(see, for example, Andrade, M. G. S., Weissman, R., and Reis, S. R.
A. 2006. "Tissue Reaction and Surface Morphology of Absorbable
Sutures after in Vivo Exposure," Journal of Materials Science:
Materials in Medicine 17(10):949-961 Bostman, O., Partio E.,
Hirvensalo, E., and Rokkanen, P. 1992. "Foreign-body Reactions to
Polyglycolide Screws: Observations in 24/216 Malleolar Fracture
Cases," Acta Orthopaedica 63(2):173-176). Solders that heat by
photosensitizing absorption of light at a certain frequency
recommend the use of combination-form barrel-assembly or radial
projection catheter with a fiber optic catheter or fiberoptic
endoscope, or angioscope, can be used to activate a photosensitive
ingredient. The same action at the same or a different frequency
can be used to release medication.
[0585] Curcumin has been demonstrated to reduce the inflammatory
response associated with poly(L-lactic acid (Dende, C., Meena, J.,
Nagarajan, P., Nagaraj, V. A., Panda, A. K., and Padmanaban, G.
2017. "Nanocurcumin is Superior to Native Curcumin in Preventing
Degenerative Changes in Experimental Cerebral Malaria," Scientific
Reports 7(1):10062; Flora, G., Gupta, D., and Tiwari, A. 2013.
"Nanocurcumin: A Promising Therapeutic Advancement Over Native
Curcumin," Critical Reviews in Therapeutic Drug Carrier Systems
30(4):331-368; Jurenka, J. S. 2009. "Anti-inflammatory Properties
of Curcumin, a Major Constituent of Curcuma Longa: A Review of
Preclinical and Clinical Research" Alternative Medicine Review
14(2):141-53; erratum at 14(3):277; Su, S. H., Nguyen, K. T.,
Satasiya, P., Greilich, P. E., Tang, L., and Eberhart, R. C. 2005.
"Curcumin Impregnation Improves the Mechanical Properties and
Reduces the Inflammatory Response Associated with Poly(L-lactic
Acid) Fiber," Journal of Biomaterials Science. Polymer Edition
16(3):353-370; Chainani-Wu, N. 2003. "Safety and Anti-inflammatory
Activity of Curcumin: A Component of Tumeric (Curcuma Longa),"
Journal of Alternative and Complementary Medicine 9(1):
161-168).
[0586] As with any substance to be implanted, to minimize if not
avert an adverse tissue response to the solder, its coatings, or
inclusions, the patient is pretested for sensitivity to various
formulations of these materials. Adverse tissue reactions can be
forestalled and possibly moderated if not eliminated to afford an
implant to dissolve, become absorbed, or intentionally extracted
through an impasse-jacket, for example, or to permit an initial
interval for tissue integration, by jacketing the implants within a
coating of scaffold material containing or itself coated with
substances such as phosphorylcholine, and/or dexamethasone, or
curcumin.
[0587] When fluid, these are used to wet implants such as
miniballs, stays, and stent-, impasse-, and magnet-jackets.
Otherwise, the retardant is prepared in the form of implant-coated
or embedded particles, microspheres, or nanorods (see, for example,
Mercanzini, A., Reddy, S. T., Velluto, D., Colin, P., Maillard, A.,
Bensadoun, J. C., Hubbell, J. A., and Renaud, P. 2010. "Controlled
Release Nanoparticle-embedded Coatings Reduce the Tissue Reaction
to Neuroprostheses," Journal of Controlled Release 145(3):196-202;
Bhardwaj, U., Papadimitrakopoulos, F., and Burgess, D. J. 2008. "A
Review of the Development of a Vehicle for Localized and Controlled
Drug Delivery for Implantable Biosensors," Journal of Diabetes
Science and Technology 2(6):1016-1029; Bhardwaj, U., Sura, R.,
Papadimitrakopoulos, F., and Burgess D. J. 2007. "Controlling Acute
Inflammation with Fast Releasing Dexamethasone-PLGA Microsphere/PVA
Hydrogel Composites for Implantable Devices," Journal of Diabetes
Science and Technology 1(1):8-17; Patil, S. D.,
Papadimitrakopoulos, F., and Burgess, D. J. 2004.
"Dexamethasone-loaded Poly(lactic-co-glycolic) Acid
Microspheres/Poly(vinyl alcohol) Hydrogel Composite Coatings for
Inflammation Control," Diabetes Technology and Therapeutics
6(6):887-897; Hickey, T., Kreutzer, D., Burgess, D. J., and Moussy,
F. 2002. "In Vivo Evaluation of a Dexamethasone/PLGA Microsphere
System Designed to Suppress the Inflammatory Tissue Response to
Implantable Medical Devices," Journal of Biomedical Materials
Research 61(2):180-187). See also the section below entitled
Medication Implants and Medicated Implants and Prongs.
[0588] For miniballs and stays, which actually penetrate through
the substrate tissue, surface treatment to moderate the reaction
that ensues following the initial adsorption of endogenous proteins
is difficult to avoid but is likely to prove critical for tissue
acceptance (see, for example, Nilsson, B., Korsgren, O., Lambris,
J. D., and Ekdahl, K. N. 2010. "Can Cells and Biomaterials in
Therapeutic Medicine be Shielded from Innate Immune Recognition?,"
Trends in Immunology 31(1):32-38; Jones, K. S. 2008. "Effects of
Biomaterial-induced Inflammation on Fibrosis and Rejection,"
Seminars in Immunology 20(2):130-136; Tang, Land Hu, W-J. 2005.
"Molecular Determinants of Biocompatibility," Expert Review of
Medical Devices. 2(4):493-500; Hu, W-J., Eaton, J. W., Ugarova, T.
P., and Tang, L. 2001. "Molecular Basis of Biomaterial-mediated
Foreign Body Reactions," Blood 98(4):1231-1238; Tang, L. and Eaton,
J. W. 1995. "Inflammatory Responses to Biomaterials," American
Journal of Clinical Pathology 103(4):466-471).
[0589] Protein adhesion a given, the surface chemistry and
topography of miniballs and stays is devised to maximize tissue
acceptance (see, for example, Morais, J. M., Papadimitrakopoulos,
F., and Burgess, D. J. 2010. "Biomaterials/Tissue Interactions:
Possible Solutions to Overcome Foreign Body Response," American
Association of Pharmaceutical Scientists Journal 12(2):188-196;
Zaveri, T. D., Dolgova, N. V., Chu, B. H., Lee, J., Wong, J., Lele,
T. P., Ren, F., and Keselowsky, B. G. 2010. "Contributions of
Surface Topography and Cytotoxicity to the Macrophage Response to
Zinc Oxide Nanorods," Biomaterials 31(11):2999-3007 Kalasin, S. and
Santore, M. M. 2009. "Non-specific Adhesion on Biomaterial Surfaces
Driven by Small Amounts of Protein Adsorption," Colloids and
Surfaces. B. Biointerfaces 73(2):229-236; Lee, J., Kang, B. S.,
Hicks, B., Chancellor, T. F Jr., Chu, B. H., Wang, H. T.,
Keselowsky, B. G., Ren, F., and Lele, T. P. 2008. "The Control of
Cell Adhesion and Viability by Zinc Oxide Nanorods," Biomaterials
29(27):3743-3749; Thevenot, P., Hu, W., and Tang, L. 2008. "Surface
Chemistry Influences Implant Biocompatibility," Current Topics in
Medicinal Chemistry 8(4):270-280; Tang, L. and Hu, W. 2005.
"Molecular Determinants of Biocompatibility," Expert Review of
Medical Devices 2(4):493-500; Kao, W. J., Liu, Y., Gundloori, R.,
Li, J., Lee, D., Einerson, N., Burmania, J., and Stevens, K. 2002.
"Engineering Endogenous Inflammatory Cells as Delivery Vehicles,"
Journal of Controlled Release 78(1-3):219-233; Jenney, C. R. and
Anderson, J. M. 1999. "Alkylsilane-modified Surfaces: Inhibition of
Human Macrophage Adhesion and Foreign Body Giant Cell Formation,"
Journal of Biomedical Materials Research 46(1):11-21; Kao, W. J.,
Hubbell, J. A., and Anderson, J. M. 1999. "Protein-mediated
Macrophage Adhesion and Activation on Biomaterials: A Model for
Modulating Cell Behavior," Journal of Materials Science. Materials
in Medicine 10(10/11):601-605).
[0590] 4b. Medicinal and Medicated Miniballs and Stays
[0591] 4b(1). Drug-Releasing and Irradiating Miniballs, Stays, and
Ferrofluids
[0592] The means described herein allow the placement of implants
in the form of miniballs or stays in locations, such as within the
walls of muscular arteries and the ureters, inaccessible to any
means of the prior art such as endoscopic. Placed thus, these
implants can be used to release any therapeutic substance which can
be prepared for release thus, or to stent, or both. Depending upon
the specific application, long- or short-term (absorbed), miniballs
and stays may be made capable of spontaneously adaptive (`smart,`
closed-loop, self-adjusted) drug release in response to the instant
milieu, or, based upon the results of follow-up examinations,
controlled from outside the body. Implants within atheromas and
tumors, for example, can be used to release antiangiogenic
medication or nanoprobes from successive or interleaved layers or
shells, for example.
[0593] Control using direct or induced heat is addressed below in
the sections entitled Implants that Radiate Heat on Demand;
Medication-coated Miniballs, Stays, and Prongs with a
Heat-activated (-melted, -denatured) Tissue Adhesive-hardener or
Binder-fixative; Heating Control over Implants and Coated Implants,
to Include Miniballs, Stays, and Prongs; Heating of Implants and
Coated Implants, to Include Miniballs, Stays, and Prongs Using
Implant-passive Ductus-external or Extrinsic Means; Extracorporeal
Energization of Intrinsic Means for Radiating Heat from Within
Medication Implants and Medication and/or the Tissue
Bonding-coatings of Implants; and Chemical Control over Implants
and Coated Implants, to Include Miniballs, Stays, and Prongs; among
others.
[0594] The stent-unrelated, or drug delivery applications of the
miniballs and stays, or ductus-intramural implants to be described,
for example, will allow medication to be released from within or
adjacent to a lesion in the wall of an anatomical structure. The
implants to be described herein can incorporate irradiating seeds
and/or medication, whether time released (prolonged release), for
insertion within a ductus wall. By contrast, long-term or sustained
delivery of a drug would require an invasive procedure for each
dose, so that for this purpose, the implants are magnetized and
placed once to attract the magnetically susceptible
nonoparticle-bound or cobound drug or drugs, as will be addressed.
While individual miniballs and stays can serve more than one
purpose, such as to stent, release, and attract medication and/or
radiation, these functions are more economically assigned to
neighboring, less specialized implants.
[0595] Noncombinatory implants are readily producible in large
numbers at relatively little cost, allow a larger dose to mass
ratio, and can be arranged in pattern, making these more versatile
than specially formulated implants. All of the drug targeting means
and procedures described herein have the object of medical
management where minor surgery is essential to gain access to the
treatment site. The interventional means for administering
medication to be described extend to new pharmacological agents, to
include gene therapeutic and nanotechnological, for example, thus
extending for the foreseeable future the continuation of
interventional methods. Ballistic implantation not only allows
temporary or permanent seed-containing miniballs to be placed where
conventional seeds can only with difficulty if at all, but reduces
the cross sectional area of the penetration path to that of the
miniball.
[0596] Drug delivering implants can be used independently of or in
conjunction with a magnetic stent-jacket (see, for example, Faxon,
D. P. (ed.) 2001. Restenosis: A Guide to Therapy, London, England:
Martin Dunitz/Informa Health Care. ISBN: 1-85317-897-7; Gruberg,
L., Waksman, R., Satler, L. F., Pichard, A. D., and Kent, K. M.
2000. "Novel Approaches for the Prevention of Restenosis," Expert
Opinion on Investigational Drugs 9(11):2555-2578) or drug-eluting
(drug coated, medicated) (see, for example, Moses, J. W.,
Kipshidze, N., and Leon, M. B. 2002. "Perspectives of Drug-eluting
Stents: The Next Revolution," American Journal of Cardiovascular
Drugs 2(3):163-172; Nowak, B., Meyer, J. M., Goergen, T., Fluehs,
D., Block, S., Guenther, R. W, Hoecker, H., and Buell U. 2001.
"Dosimetry of a 188rhenium-labeled Self-expanding Stent for
Endovascular Brachytherapy in Peripheral Arteries," Cardiovascular
Radiation Medicine 2(4):246-253). Miniballs and stays can be open
or closed-loop `smart pills,` for permanent or temporary placement
(Bawa, P., Pillay, V., Choonara, Y. E., and du Toit, L. C. 2009.
"Stimuli-responsive Polymers and Their Applications in Drug
Delivery," Biomedical Materials 4(2):022001; Alvarez-Lorenzo, C.
and Concheiro, A. 2008. "Intelligent Drug Delivery Systems:
Polymeric Micelles and Hydrogels," Mini Reviews in Medicinal
Chemistry 8(11):1065-1074); Traitel, T., Goldbart, R., and Kost, J.
2008. "Smart Polymers for Responsive Drug-delivery Systems,"
Journal of Biomaterials Science. Polymer Edition 19(6):755-767;
Moschou, E. A., Madou, M. J., Prescott, J. H., Lipka, S., Baldwin,
S., Sheppard, N. F. Jr, and 5 others 2006. "Chronic, Programmed
Polypeptide Delivery from an Implanted, Multireservoir Microchip
Device," Nature Biotechnology 24(4):437-438; Bachas, L. G., and
Daunert, S. 2006. "Voltage-switchable Artificial Muscles Actuating
at Near Neutral pH," Sensors and Actuators B: Chemical
115(1):379-383; Xu, H., Wang, C., Wang, C., Zoval, J., and Madou,
M. 2006. "Polymer Actuator Valves Toward Controlled Drug Delivery
Application," Biosensors and Bioelectronics 21(11):2094-2099).
[0597] In addition to drugs already mentioned, numerous other
substances have been implemented or proposed for inhibiting intimal
(endarterial) thickening, to include growth factor blockers (see,
for example, Asada, Y., Tsuneyoshi, A., Marutsuka, K, and
Sumiyoshi, A. 1994. "Suramin Inhibits Intimal Thickening Following
Intimal Injury in the Rabbit Aorta in Vivo," Cardiovascular
Research 28(8):1166-1169), policosanol (Noa, M., Mas, R., and Mesa,
R. 1998. "Effect of Policosanol on Intimal Thickening in Rabbit
Cuffed Carotid Artery," International Journal of Cardiology
67(2):125-132; Noa, M., Mas, R., and Lariot, C. 2007. "Protective
Effect of Policosanol on Endothelium and Intimal Thickness Induced
by Forceps in Rabbits," Journal of Medicinal Food 10(3):452-459),
glycoprotein IIb/IIIa receptor antagonists, nitric oxide (nitrogen
monoxide, an endothelium-derived relaxing factor) donors (see
Lefkovits, J. and Topol, E. J. 1997. "Pharmacological Approaches
for the Prevention of Restenosis after Percutaneous Coronary
Intervention," Progress in Cardiovascular Diseases 40(2):141-158),
and vascular neutral endopeptidase (Barber, M. N., Kanagasundaram,
M., Anderson, C. R., Burrell, L. M., and Woods, R. L. 2006.
"Vascular Neutral Endopeptidase Inhibition Improves Endothelial
Function and Reduces Intimal Hyperplasia," Cardiovascular Research
71(1): 179-188). Vascular endothelial growth factor receptor 2 has
been found to retard atherogenesis in mice (Hauer, A. D., van
Puijvelde, G. H., Peterse, N., de Vos, P., and eight other authors,
2007. "Vaccination Against VEGFR2 Attenuates Initiation and
Progression of Atherosclerosis," Arteriosclerosis, Thrombosis, and
Vascular Biology 27(9):2050-2057).
[0598] Except when accidently released, dropped, or mispositioned,
implants other than temporary irradiating seeds, which are
exceptional, are not intended for recovery. If necessary, any
miniball or stay can include ferrous matter and be recovered using
the recovery electromagnet built into same barrel-assembly or that
of the same stay insertion tool that was used to place the implant,
whether immediately as when mispositioned, or at a later date, such
as with a temporary seed on the basis of results at an interval
following placement. Provided sufficient continuous ferromagnetic
material is incorporated into a medication miniball, for example,
the miniball can be remotely, noninvasively, heated by placing the
patient in a radiofrequency alternating magnetic or electromagnetic
field. Induction heating further allows the noninvasive detection
of implant temperature by means of an equivalent temperature
calibrated eddy current detector.
[0599] In extraluminal stent-jackets, this allows the
postprocedural thermoplasty of reobstructive hyperplasia by
noninvasive heating of the jacket with the temperature
noninvasively read by means of an equivalent temperature calibrated
eddy current detector. Moreover, because the intensity of induction
can be increased as necessary, stent-jackets intended to be
noninvasively heatable need not coordinate the number of
`breathing` perforations seen as 119 in FIGS. 6, 13, 14, and 15
with resistance to eddy current circuits. Dipolar polymers such as
acetates, polyvinyl chrloride, and polyamides, notably nylon, which
are likewise heated when placed in a radio frequency alternating
magnetic or electromagnetic field are avoided when their
resilience, springiness, or shape-restorative property is used.
[0600] When heated in the internal environment, some plastics may
additionally release harmful degradation products. Stretched
segments anticipated to reocclude can thus be preemptively jacketed
to counter this eventuality even where no ductus-intramural
implants have been placed. The noninvasive heating of nonabosrbable
and absorbable implants has many applications, to include on-demand
dissolution, release of medication, accelerated drug uptake and
healing, pain reduction, and reducing the setting and curing times
of a surgical cement, and. Unless rippled to increase the surface
area for quicker dissolution, nonpermanent or absorbable implants,
usually medicinal, are smooth and include ferrous material only to
allow magnetic recovery if necessary.
[0601] In absorbable implants such as medication miniballs and
stays, the polymer of the matrix or polymers of the layers thereof,
or the medication or layers thereof whether time-released, or any
combination of the foregoing, set the period or successive
intervals for dissolution. The depth of the layer that incorporates
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder, for example, depends upon the potential need to
retrieve what remains of the implant were it to become
mispositioned. That is, retrievability is lost upon dissolution of
the deepest layer containing ferromagnetic material. Implants
intended for use as the intraductal component of an extraluminal
magnetic stent require a higher proportion of ferrous material,
generally not dispersed superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder, but rather conformed for
optimal susceptibility to magnetic tractive force and chemically
isolated as a core for permanence.
[0602] A stent, or stenting, miniball can be given outer layers of
therapeutic substances, of course. Such substances when present
directly support implantation, and typically include antiseptics,
antibiotics, lubricants, tissue cements, protein solders, and
numerous others singly or severally. Permanent implants include the
intravascular components of magnetic stents and/or nontemporary
(low dose-rate) irradiating seeds, which can also be enclosed
within layers of therapeutic agents. The permanent or nonabsorbable
surface of a permanent implant is given a deeply textured surface
and otherwise treated to encourage tissue adhesion, infiltration,
and integration. To the extent that a dense and deep surface
texture allows propulsive gas to escape about the miniball
periphery during discharge, the loss in expulsive force must be
compensated for by increasing the exit velocity (`muzzle
velocity`). To offset losses in exit velocity due to leakage or
adjust for differences in tissue hardness, an interventional airgun
must allow regulation of the expulsive force.
[0603] This capability also allows reducing the velocity to control
the depth of miniball penetration and avoid perforations. Where the
length of the ductus to be implanted with medication or radiation
seeds, for example, is large, but focused drug targeting or
irradiation is wanted, nonstenting medication or radiation seed
miniballs, which do not require local percutaneous entry either to
gain access as do stays nor to place a jacket, are used. This
eliminates any extensive percutaneous access. Whereas to place any
number, size, or type of miniballs necessitates single percutaneous
entry and withdrawal and can be accomplished with accuracy in a
relatively short time, the prior art alternative of placing
multiple endoluminal stents requires but single femoral, cubital,
or brachial (radial) entry, but repeated withdrawal and reentry to
separately place each stent.
[0604] Repeated withdrawal and entry increases the risk of entry
wound hematoma and infection and increases procedural time. If the
miniballs are to be used for stenting, then depending upon how
closely together extraluminal stents are to be placed, a separate
access incision at the body surface allows placement of from 1 to 3
extraluminal stents without repeated irritation of a single entry
wound. With a barrel-assembly equipped with a built-in wide angle
fiberoptic endoscope or angioscope or a combination-form
barrel-assembly with such a device inserted through its central
channel to afford a clear view, miniballs can be accurately placed.
If the ductus is malacotic, determined by the means described in
the section below entitled Testing and Tests, implantation by
ballistic means may be discounted and stays, which involve no
transluminal component to place, are used.
[0605] If the number of ductus-intramural implants is relatively
few, a malacotic ductus may be implanted if first treated to
strengthen or bind it, as addressed below in the section entitied
Medication-coated Miniballs, Stays, and Prongs with a
Heat-activated (-melted, -denatured) Tissue Adhesive-hardener or
Binder-fixative. If only slightly malacotic, a tissue hardener and
prepositioned double-wedge stent-jacket rebound-directing lining
insert, as addressed below in the section of like title may be used
to prevent perforations. The terms `tissue hardener` and
`sclerosant` in this context refer to stiffening agents that
indurate malacotic tissue, not to agents used to embolize a
varicosity or a polyp, for example. The means to be described
provide additional methods of treatment using radiation
(brachytherapy endocurietherapy, sealed source radiotherapy).
[0606] Currently, high dose-rate treatment is applied with a remote
afterloader, which has limited organ applicability, and must be
withdrawn leaving no radioactive substance in the patient. This
denies the ability to terminate the treatment based upon
reexaminations at intervals without the need to repeat the
procedure. The embedding and suturing of multiple interstitial high
dose-rate catheter sleeves or trocars and the passing therethrough
of source guides, for example, is sufficiently intricate as to
discourage repeated treatments thus. Aside from the relative
difficulty, longer procedural time, and greater trauma of
introducing conventional seeds, especially into the walls of
lumina, low dose-rate conventional seeds, as well as stents, are
implanted with no expectation of recovery following treatment,
limiting the dose-rate.
[0607] Affording comparable results at greater convenience to the
patient, the use of a higher dose-rate has been recommended over
lower dose-rate brachytherpy in the treatment of cervical cancer,
for example (see, for example, Wang, X., Liu, R., Ma, B., Yang, K.,
Tian, J., and 7 others 2010. "High Dose Rate Versus Low Dose Rate
Intracavity Brachytherapy for Locally Advanced Uterine Cervix
Cancer," Cochrane Database of Systematic Reviews (online)
7:CD007563; Viani, G. A., Manta, G. B., Stefano, E. J., and de
Fendi, L. I. 2009. "Brachytherapy for Cervix Cancer: Low-dose Rate
or High-dose Rate Brachytherapy--A Meta-analysis of Clinical
Trials," Journal of Experimental and Clinical Cancer Research
5;28:47). In addition to directly targeted treatment, malignant
tumors that shed `daughter` cells which travel through the
bloodstream to induce metastases elsewhere in the body, and persist
after the primary tumor has been eliminated, require systemic
chemotherapy.
[0608] However, because nontargeted tissue is little exposed, the
less so when a counteractant is available, a directly targeted
tumor can be treated with more concentrated and if appropriate,
radioactive medication As addressed above in the section entitled
Field of the Invention and in the sections below in order entitled
Drug-releasing and Irradiating Miniballs, Stays, and Ferrofluids,
Drug-targeting Miniballs and Stays, 80 and Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays, among others,
isolated lesions can be magnetically targeted for chemotherapy as
well as radiation and/or surgery and for neoadjuvant chemotherapy
preparatory to surgical resection of a tumor. The spherical seed
miniballs are magnetically extracted through penetration paths no
greater in cross sectional area than the seeds. If the coating of
platelet blockade about the seed-miniballs is not sufficient to
suppress thrombosis on insertion, then systemic medication is
required as when the miniballs are eventually recovered.
[0609] Higher dose-rates have also been shown more effectively
palliative for the treatment of advanced carcinoma (see, for
example, Skowronek, J., Piotrowski, T., and Zwierzchowski, G. 2004.
"Palliative Treatment by High-dose-rate Intraluminal Brachytherapy
in Patients with Advanced Esophageal Cancer," Brachytherapy
3(2):87-94; Skowronek, J., Piotrowski, T., Mlynarczyk, W., and
Ramlau, R. 2004. "Advanced Tracheal Carcinoma--Therapeutic
Significance of HDR Brachytherapy in Palliative Treatment,"
Neoplasma 51(4):313-318; Churn, M., Jones, B., and Myint, A. S.
2002. "Radical Radiotherapy Incorporating a Brachytherapy Boost for
the Treatment of Carcinoma of the Thoracic Oesophagus: Results from
a Cohort of Patients and Review of the Literature," Clinical
Oncology (Royal College of Radiology). 14(2):117-122; Sur, R. K.,
Donde, B., Levin, V. C., and Mannell, A. 1998. "Fractionated High
Dose Rate Intraluminal Brachytherapy in Palliation of Advanced
Esophageal Cancer," International Journal of Radiation Oncology,
Biology, and Physics 40(2):447-453). Used in arteries, radioactive
stents have been found to cause narrowing at the margins and
substantially eliminated from use (Waksman, R. 2006.
"Catheter-Based Radiation," in Ellis, S. G. and Holmes, D. R. Jr.
Strategic Approaches in Coronary Intervention, Philadelphia, Pa.:
Lippincott Williams and Wilkins, page 161).
[0610] Intermediate dose-rate implants are not introduced with the
expectaton of retrieval based upon followup diagnostics at
intervals following implantation. Additionally, whereas an
irremovable dose-rate limited irradiating stent is endoluminal and
interferes with vasomotility and the passing through of contents, a
radiation emitting seed-stay is extraluminal (ductus-intramural).
Irradiating miniballs, whether containing a seed-core or a
radiactive coating, can be implanted in the walls of the
gastrointestinal tract, for example, then recovered with slight
trauma based upon the results of followup examinations. By
contrast, once decayed, conventional seeds are left implanted.
[0611] The Cordis Checkmate.TM. System--P990036 uses seeds to treat
in-stent restenosis (see, for example, Waksman, op cit, page 162).
Unlike radiation seeds, which left in place, are limited to low
dose-rates or radionuclides (radioisotopes) of short half-life such
as Xenon-133 (see, for example, Sekine, T., Watanabe, S., Osa, A.,
Ishioka, N., and nine other inventors, 2001. "Xenon-133 Radioactive
Stent for Preventing Restenosis of Blood Vessels and a Process for
Producing the Same," U.S. Pat. No. 6,192,095), ductus-intramurally
placed stays and miniballs are practicably recoverable and thus
usable for delivering medication or radiation in higher doses for a
limited period.
[0612] In more advanced disease, external beam radiation may be
essential to supplement the radiation provided by seeds. In the
irradiaton intervening tissue, this negates the key benefit in the
use of seeds over external irradiaton or delivery through the
systemic circulation by infusion or ingestion. The means to be
described assume the recoverable implantation of variable dose-rate
miniballs or stays, making extended exposure to radiation possible
without the need to introduce additional irrecoverable seeds or
stents, and without the need for any foreign object in the lumen
where it interferes with the pulse or peristalsis and can result in
numerous complications.
[0613] Existing nominally permanent seeds implanted in patients
previously treated for a malignancy can, if infrequently, demand
periodic reexamination or surgical excision (see, for example,
Sachdeva, S., Udechukwu, N. S., Elbelasi, H., Landwehr, K. P., St
Clair, W. H., and Winkler, M. A. 2016. "Prostate Brachytherapy Seed
Migration to the Heart Seen on Cardiovascular Computed Tomographic
Angiography," Radiology Case Reports 12(1):31-33; Calvert, A. D.,
Dyer, A. W., and Montgomery, V. A. 2016. "Embolization of Prostatic
Brachytherapy Seeds to Pulmonary Arteries: A Case Study," Radiology
Case Reports 12(1):34-38; Nguyen, B. D., Schild, S. E., Wong, W.
W., and Vora, S. A. 2009. "Prostate Brachytherapy Seed Embolization
to the Right Renal Artery," Brachytherapy 8(3):309-312; Stewart, A.
J., O'Farrell, D. A., Mutyala, S., Bueno, R., Sugarbaker, D. J.,
Cormack, R. A., and Devlin, P. M. 2007. "Severe Toxicity after
Permanent Radioactive Seed Implantation for Mediastinal Carcinoid
Tumors," Brachytherapy 6(1):58-61; Ankem, M. K., DeCarvalho, V. S.,
Harangozo, A. M., Hartanto, V. H., Perrotti, M., and 8 others 2002.
"Implications of Radioactive Seed Migration to the Lungs after
Prostate Brachytherapy," Urology 59(4):555-559).
[0614] The miniballs or stays can contain a seed-core, carry a
radioactive coating, or have a surface that has been ion
impregnated. Stay insertion tools as shown in FIGS. 87, 88 thru 91,
with a detailed view provided in FIG. 95 and described in section
below entitled XVI. Stay Insertion Tools, incorporate a surgical
cyanoacrylate cement stay coater to positionally stabilize each
stay, extending the time for fibrous encapsulation. Almost all
miniballs and stays incorporate sufficient ferromagnetic material
to allow recovery. The use of these in high motility ductus such as
the gastrointestinal tract makes possible, for example, the
placement of higher dose-rate seeds on a temporary basis. Another
advantage of implants other than irretrievable endoluminal stents
are adaptability to normal growth, changes in the pathology, or
both.
[0615] Existing radioactive seeds and stents are not readily
adapted for use in the luminal walls of most structures, such as
the great vessels and heart (see, for example, Talukder, M. Q.,
Deo, S. V., Maleszewski, J. J., and Park, S. J. 2010. "Late
Isolated Metastasis of Renal Cell Carcinoma in the Left Ventricular
Myocardium," Interactive Cardiovascular and Thoracic Surgery
11(6):814-816; Omura, A., Tobe, S., Yoshida, K., and Yamaguchi, M.
2008. "Surgical Treatment for Recurrent Pulmonary Artery Sarcoma,"
General Thoracic and Cardiovascular Surgery 56(1):28-31 Rastan, A.
J., Walther, T., Mohr, F. W., and Kostelka, M. 2004.
"Leiomyosarcoma--An Unusual Cause of Right Ventricular Outflow
Tract Obstruction," Thoracic and Cardiovascular Surgeon
52(6):376-377; Sanchez-Munoz, A., Hitt, R., Artiles, V., Lopez, A.,
Hernandez, R., Cortes-Funes, H., and Colomer, R. 2003. "Primary
Aortic Sarcoma with Widespread Vascular Embolic Metastases,"
European Journal of Internal Medicine 14(4):258-261; Ceccaldi, B.,
Dourthe, L. M., Garcin, J. M., Vergeau, B., Chanudet, X., and
Larroque, P. 2000. "Leiomyosarcome cardiaque du ventricule droit
[Leiomyosarcoma of the Right Ventricle]," (in French with abstract
in English at Pubmed) Bulletin du Cancer (Bulletin of Cancer)
87(7-8):547-550; al-Robaish, A., Lien, D. C., Slatnik, J., and
Nguyen, G. K. 1995. "Sarcoma of the Pulmonary Artery Trunk: Report
of a Case Complicated with Hemopericardium and Cardiac Tamponade,"
Canadian Journal of Cardiology 11(8):707-709; Thijs, L. G., Kroon,
T. A., and van Leeuwen, T. M. 1974. "Leiomyosarcoma of the
Pulmonary Trunk Associated with Pericardial Effusion," Thorax
29(4):490-494).
[0616] Within an artery, the traveling radial excursion and return
of the wall by the pulse is not large enough to result in
significant implant mispositionings. Moreover, in a coronary
artery, the muzzle-head moves closely enough with the beating heart
that wobble does not affect implant positioning to any significant
extent. Thus, as with conventional interventional apparatus,
substantially conjoint movement with the containing coronary artery
allows procedures to be performed off-pump. The movement of blood
past the muzzle-head by the pulse is dependent upon the diameter
and length of the muzzle-head, whether the muzzle-head incorporates
a bypass groove or grooves, is of the combination-form type with an
unoccupied bore to allow blood to pass through, the elasticity of
the artery, and the blood pressure.
[0617] By contrast, the insertion of stays in a coronary artery
must be performed on-pump. Except in the trachea and
gastrointestentstinal tract, to which access does not require
incision, the administration of medication in the form of miniballs
or stays is normally undertaken as secondary to and supportive of
an antecedent or primary reason for entry, usually to ablate and/or
stent; generally, only a localized and exigent condition such as a
tumor justifies administration thus. Unlike parenteral
administration whether oral, by injection, or infusion, medicinal
implants of the kind to be described impart the ability to target
diseased tissue within the wall of a ductus, for example, at too
awkward an angle and in too small as size as would allow injection
endoscopically. This allows the use of a small but concentrated
dose with less systemic dispersion. Existing methods do not allow
injection much less quick shot-delivery into the walls of small
lumina.
[0618] The ability to target medication poses benefits in terms of
efficacy and reducing side effects, as well as in economy and
efficiency, and should continue to be of benefit long past the age
of mechanical intervention for most other purposes when
nanotechnological and gene therapeutic modalities will be
prevalent. The simplest and least expensive barrel-assemblies
provide this capability. Whether a miniball introduced from within
the lumen or a stay introduced through the outer tunic, the lesion
or tissue targeted implant is formulated using methods already
known in the pharmaceutical field to release different contents at
the same or different intervals and rates. Following placement, the
implant can be acted upon extracorporeally such as through the
application of heat, to effect its dissolution or the release of
constituents in a temperature selective manner, for example. The
concentric layering of medication for differential release after
infixion when desired by magnetic force, heat, or chemical
exposure, for example, are all possible.
[0619] The selective breakdown of microspheres or nanotubes within
layers or of continuous layers one or more at a time at later dates
allows medication to be prepositioned for dispersal as periodic
followup reevaluations indicate. The combination of medication
miniballs, and magnetically susceptible drug carrier bound
nanoparticles introduced in a ferrofluid, for example, with
impasse-jackets expands the scope of drug delivery. Different forms
of drug targeting are described. Miniballs and stays can deliver a
drug or other therapeutic substance from a point by simple or
time-prolonged (time-released) dissolution or by elution. Miniballs
and stays include sufficient superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder or magnetically
susceptible content for retrieval if misplaced, and increasing this
content allows initiating and/or accelerating drug delivery by
direct or induction heating.
[0620] Since an invasive procedure is required and the site of
release cannot be replenished at will as can an impasse-jacket,
this form of drug targeting is almost always limited to incidental
or adjunct application during a primary invasive procedure
catheteric or through open exposure that is essential. Miniballs
that consist of a drug or drugs can be interspersed among stenting
miniballs, for example. Whereas implanted miniballs and stays are
embedded within the diseased tissue, limiting followup access to
these by absorption through the lumen wall or injection with the
aid of radial projection unit (side-looking) injection
tool-inserts, a miniball, for example, suspended in the lumen by an
impasse-jacket remains accessible to substances administered at a
later time whether orally or by injection to end or modify its
action.
[0621] That is, an impasse-jacket allows follow-up access to the
suspendant and is rechargeable (replenishable) to allow continued
or adjusted administration of a drug or drugs as necessary.
Injected miniballs, microspherules, and prospectively, ingested
drug carrier nanoparticles can be trapped and suspended in the
lumen by an impasse-jacket to deliver a drug through any of the
foregoing processes repeatedly at any time. Lumen side-looking
injectors, radial discharge barrel-assemblies, and impasse-jackets
able to deliver mediation into the wall surrounding a delimited
segment of even a small ductus where no means could do so before,
the facility of treatment may be critically augmented. With certain
conditions, this can justify the invasive procedure to place the
jacket.
[0622] Atherosclerosis consists of a systemic inflammation
throughout the arterial tree but most prominent and vulnerable at
discrete sites where the forces generated by lumen conformation and
flow produces lesions the location of which are predictable at
bifurcations. The object in treatment should be to reinstate normal
endothelial function and the healing of frank lesions. This is
accomplished with a statin (3-hydroxy-3-methylglutaryl-coenzyme A
(or HMG-CoA) reductase inhibitor) in the systemic circulation and
the singling out lesions for special treatment. While mildly
inflamed intima treated only medically should re-endothelialize and
recover without scarring or the formation of neointima, severely
diseased tissue warrants elimination to avert an acute event
despite the probability that the condition itself and the treatment
will detain if not preclude eventual healing of which the lesion
was probably incapable in any event.
[0623] One means for the spot treatment of lesions that reduces the
risk for thrombogenesis is thermoplasty (see, for example,
Lawrence, J. B., Prevosti, L. G., Kramer, W. S., Smith, P. D.,
Bonner, R. F., Lu, D. Y., and Leon, M. B. 1992. "Pulsed Laser and
Thermal Ablation of Atherosclerotic Plaque: Morphometrically
Defined Surface Thrombogenicity in Studies Using an Annular
Perfusion Chamber," Journal of the American College of Cardiology
19(5):1091-1100; Lawrence, J. B., Prevosti, L. G., Kramer, W. S.,
Lu, D. Y., and Leon, M. B. 1989. "Platelet Adherence and Thrombus
Formation with Flowing Human Blood on Atherosclerotic Plaque:
Reduced Thrombogenicity of Watanabe-heritable Hyperlipidemic Rabbit
Aortic Subendothelium," Thrombosis Research 54(2):99-114).
[0624] Targeted statin delivery, for which impasse-jackets, for
example, can be pre-positioned, allows a considerably reduced serum
or systemic background level of a statin to be administered,
minimizing adverse side effects, while segments which are already
or can be predicted to become severely atheromatous can be given a
concentrated dose. The background or systemically circulated statin
enhances the catabolism of low density lipoprotein by the liver,
whereas that targeted at the atheromatous lesion delivers other
beneficial effects of the statin.
[0625] In atherosclerosis, endothelial activation and dysfunction
lead to chronic intimal inflammation and atheromatous lesioning
(Alom-Ruiz, S. P., Anilkumar, N., and Shah, A. M. 2008. "Reactive
Oxygen Species and Endothelial Activation," Antioxidants and Redox
Signaling 10(6): 1089-1100). Atheromatous lesions and transluminal
interventions are both associated with endothelial dysfunction
(Padfield, G. J., Newby, D. E., and Mills, N. L. 2010.
Understanding the Role of Endothelial Progenitor Cells in
Percutaneous Coronary Intervention," Journal of the American
College of Cardiology 55(15):1553-1565; Caramori, P. R. A.; Lima,
V. C.; Seidelin, P. H.; Newton, G. E; Parker, J. D; Adelman, A. G.
1999. "Long-term Endothelial Dysfunction after Coronary Artery
Stenting," Journal of the American College of Cardiology 34(6):
1675-1679).
[0626] However, if reinstatable to normal endothelial function,
sites of vulnerable plaque may take a long time to do so, and in
the meantime pose an immediate risk of rupture with dangerous
consequences, as to demand active intervention. Whether intimal
tissue in a state of chronic inflammation or frankly atheromatous
has the potential to recover to a state of normal endothelial
function with treatment would appear to depend upon how severe are
the disease and how traumatizing the treatment. Statins having been
shown to exert a considerable healing effect on diseased intima,
searing and/or targeting of atheromatous lesions with a statin at a
concentration higher than should be circulated with a background of
circulated statin to treat chronically inflamed intima is an
approach that the inventive system makes possible.
[0627] A statin applied directly to an atheromatous segment without
passing through or being limited to the liver provides direct
benefits for the consequences of protracted elevated serum
cholesterol and not just a reduction in serum cholesterol
production as such, as well as exercises a demonstrable healing
function in vascular tissue (see, for example, Mitsuhashi, T.,
Uemoto, R., Ishikawa, K., Yoshida, S., Ikeda, Y., and 4 others
2018. "Endothelial Nitric Oxide Synthase-independent Pleiotropic
Effects of Pitavastatin against Atherogenesis and Limb Ischemia in
Mice," Journal of Atherosclerosis and Thrombosis 25(1):65-80;
Gavazzoni, M., Gorga, E., Derosa, G., Maffioli, P., Metra, M., and
Raddino, R. 2017. "High-dose Atorvastatin Versus Moderate Dose on
Early Vascular Protection after ST-elevation Myocardial
Infarction," Drug Design, Development, and Therapy 11:3425-3434;
Balan, A., Szaingurten-Solodkin, I., Swissa, S. S., Feinshtein, V.,
Huleihel, M., and 3 others 2017. "The Efects of Pravastatin on the
Normal Human placenta: Lessons from ex-vivo models," Public Library
of Science One 12(2):e0172174; Akarsu, M., Saygun, O., Aydinuraz,
K., Aydin, O., Daphan, C. E., and 3 others 2017. "The Effects of
Simvastatin on Ischemia Reperfusion Injury in an Experimental Colon
Anastomosis Model," Indian Journal of Surgery 79(5):390-395; Owens,
A. P. 3rd, Passam, F. H., Antoniak, S., Marshall, S. M., McDaniel,
A. L., Rudel, L., Williams J. C., and 15 others 2012. "Monocyte
Tissue Factor-dependent Activation of Coagulation in
Hypercholesterolemic Mice and Monkeys is Inhibited by Simvastatin,"
Journal of Clinical Investigation 122(2):558-568; Silverstein, R.
L. 2012. "Teaching an Old Dog New Tricks: Potential
Antiatherothrombotic Use for Statins," Journal of Clinical
Investigation 122(2):478-481; Marzilli, M. 2010. "Pleiotropic
Effects of Statins: Evidence for Benefits Beyond LDL-cholesterol
Lowering.," American Journal of Cardiovascular Drugs 10 Supplement
1:3-9; Pedersen, T. R. 2010. "Pleiotropic Effects of Statins:
Evidence Against Benefits Beyond LDL-cholesterol Lowering,"
American Journal of Cardiovascular Drugs 10 Supplement 1:10-17;
Smaldone, C., Brugaletta, S., Pazzano, V., and Liuzzo, G. 2009.
"Immunomodulator Activity of 3-hydroxy-3-methilglutaryl-CoA
Inhibitors," Cardiovascular and Hematological Agents in Medicinal
Chemistry 7(4):279-94; Ii, M. and Losordo, D. W. 2007. "Statins and
the Endothelium," Vascular Pharmacology 46(1):1-9; Dilaveris, P.,
Giannopoulos, G., Riga, M., Synetos, A., and Stefanadis, C. 2007.
"Beneficial Effects of Statins on Endothelial Dysfunction and
Vascular Stiffness," Current Vascular Pharmacology 5(3):227-237;
Calabr , P. and Yeh, E. T. 2005. "The Pleiotropic Effects of
Statins," Current Opinion in Cardiology 20(6):541-546).
[0628] The pleiotropic or liver metabolism-independent/local
application potential of relatively new drugs, such as proprotein
convertase subtilisin/kexin type 9 (PCSK9) inhibitors and
investigatory or experimental small interference RNA PCSK9
messenger RNA inhibitor (inclisiran) (see, for example, Fitzgerald,
K., White, S., Borodovsky, A., Bettencourt, B. R., Strahs, A., and
10 others 2017. "A Highly Durable RNAi Therapeutic Inhibitor of
PCSK9," New England Journal of Medicine 376(1):41-51; Ray, K. K.,
Landmesser, U., Leiter, L. A., Kallend, D., Dufour, R., and 8
others 2017. "Inclisiran in Patients at High Cardiovascular Risk
with Elevated LDL Cholesterol," New England Journal of Medicine
376(15):1430-1440; Hadjiphilippou, S. and Ray, K. K. 2017. "PCSK9
Inhibition and Atherosclerotic Cardiovascular Disease Prevention:
Does Reality Match the Hype?," Heart (British Cardiac Society)
103(21):1670-1679; Shah, P., Glueck, C. J., Goldenberg, N., Min,
S., Mahida, C., and 4 others 2017. "Efficacy, Safety, Low Density
Lipoprotein Cholesterol Lowering, and Calculated 10-year
Cardiovascular Risk Reduction of Alirocumab and Evolocumab in
Addition to Maximal Tolerated Cholesterol Lowering Therapy: A
Post-commercialization Study," Lipids in Health and Disease
16(1):19; Choi, J., Khan, A. M., Jarmin, M., Goldenberg, N.,
Glueck, C. J., anf Wang, P. 2017. "Efficacy and Safety of
Proprotein Convertase Subtilisin-Kexin Yype 9 (PCSK9) Inhibitors,
Alirocumab and Evolocumab, a Post-commercialization Study," Lipids
in Health and Disease 16(1):141; Wici ski, M., ak, J., Malinowski,
B., Popek, G., and Grze k, G. 2017. "PCSK9 Signaling Pathways and
Their Potential Importance in Clinical Practice," European
Predictive Medicine Association Journal 8(4):391-402; Schulz, R.
and Schluter, K. D. 2017. "PCSK9 Targets Important for Lipid
Metabolism," Clinical Research in Cardiology Supplements
12(Supplement 1):2-11; Glerup, S., Schulz, R., Laufs, U., and
Schluter, K. D. 2017. "Physiological and Therapeutic Regulation of
PCSK9 Activity in Cardiovascular Disease," Basic Research in
Cardiology 112(3):32; Seidah, N. G. 2016. "New Developments in
Proprotein Convertase Subtilisin-Kexin 9's Biology and Clinical
Implications," Current Opinion in Lipidology 27(3):274-281; Gupta,
S. 2016. "Development of Proprotein Convertase Subtilisin/Kexin
Type 9 Inhibitors and the Clinical Potential of Monoclonal
Antibodies in the Management of Lipid Disorders," Vascular Health
and Risk Management 12:421-433; McDonagh, M., Peterson, K.,
Holzhammer, B., and Fazio, S. 2016. "A Systematic Review of PCSK9
Inhibitors Alirocumab and Evolocumab," Journal of Managed Care and
Specialty Pharmacy 22(6):641-653q; Zhang, L., Song, K., Zhu, M.,
Shi, J., Zhang, H., Xu, L., and Chen, Y. 2016. "Proprotein
Convertase Subtilisin/Kexin Type 9 (PCSK9) in Lipid Metabolism,
Atherosclerosis, and Ischemic Stroke," International Journal of
Neuroscience 126(8):675-680; Urban, D., Poss, J., Bohm, M., and
Laufs, U. 2013. "Targeting the Proprotein Convertase
Subtilisin/Kexin Type 9 for the Treatment of Dyslipidemia and
Atherosclerosis," Journal of the American College of Cardiology
62(16):1401-1408; Steinberg, D. and Witztum, J. L. 2009.
"Inhibition of PCSK9: A Powerful Weapon for Achieving Ideal LDL
Cholesterol Levels," Proceedings of the National Academy of
Sciences of the United States of America 106(24):9546-9547),
cholesterylester transfer protein (CETP) inhibitors (see, for
example, Han, S., Levoci, L., Fisher, P., Wang, S. P., and 7 others
2012. "Inhibition of Cholesteryl Ester Transfer Protein by
Anacetrapib Does Not Impair the Anti-inflammatory Properties of
High Density Lipoprotein," Biochimica et Biophysica Acta December
23 pii: S1388-1981(12)00262-00264; Nicholls, S. J., Brewer, H. B.,
Kastelein, J. J., Krueger, K. A., Wang, M. D., and 4 others 2011.
"Effects of the CETP Inhibitor Evacetrapib Administered as
Monotherapy or in Combination with Statins on HDL and LDL
Cholesterol: A Randomized Controlled Trial," Journal of the
American Medical Association 306(19):2099-2109), such as
anacetrepib (Merck), evacetrapib (Lilly), currently under clinical
trials, or isolated ethyl eicosapentaenoic acid (Vascepa.RTM.
(Amarin), Epadel.RTM. (Mochida) to function locally or
pleiotropically as do statins appears not as yet to have been
investigated.
[0629] In addition to raising high density lipoprotein, this class
of drugs appears to decrease low density lipoprotein more than the
reduction obtained with a statin alone, and may prove valuable on
that basis. However, the drug-induced high density lipoprotein
produced appears dissimilar from that originated in the gut and
liver (see, for examples, Rader, D. J. and Hobbs, H. H., 2005.
"Disorders of Lipoprotein Metabolism," Chapter 335, page 2288, in
Harrison's Principles of Internal Medicine, New York, N.Y.:
McGraw-Hill) and relatively ineffective at recovering cholesterol
and other lipids, to include that within atheromatous tissue, and
transporting it to the liver for reformulation or breakdown and
disposal, which subject is under study (see, for example, Nicholls,
S. J., Gordon, A., Johannson, J., Ballantyne, C. M., Barter, P. J.,
Brewer, H. B., Kastelein, J. J., Wong, N. C., Borgman, M. R., and
Nissen, S. E. 2012. "ApoA-I Induction as a Potential
Cardioprotective Strategy: Rationale for the SUSTAIN and ASSURE
Studies," Cardiovascular Drugs and Therapy 26(2): 181-187).
[0630] Rather than to force the natural production of defective
high density lipoprotein, one approach would be to directly
synthesize a molecule identical to natural high density lipoprotein
and directly pipe it to the circulatory system through a
nonmagnetized or magnetized jacket from a portal implanted at t he
body surface as described herein. Awareness of the pleiotropic
effects of statins has existed for years (Lahera, V., Goicoechea,
M., de Vinuesa, S. G., Miana, M., de las Heras, N., Cachofeiro, V.,
and Luno, J. 2007. "Endothelial Dysfunction, Oxidative Stress and
Inflammation in Atherosclerosis: Beneficial Effects of Statins,"
Current Medicinal Chemistry 14(2):243-248; Sipahi, I., Nicholls, S.
J., Tuzcu, E. M., and Nissen, S. E. 2006. "Coronary Atherosclerosis
Can Regress with Very Intensive Statin Therapy," Cleveland Clinic
Journal of Medicine 73(10):937-944; Nissen, S. E., Nicholls, S. J.,
Sipahi, I., Libby, P., Raichlen J. S, Ballantyne C M, Davignon J,
and 9 other ASTEROID Trial Investigators 2006. "Effect of Very
High-intensity Statin Therapy on Regression of Coronary
Atherosclerosis: The ASTEROID Trial," Journal of the American
Medical Association 295(13):1556-1565; Arnaud, C., Veillard, N. R.,
Mach, F. 2005. "Cholesterol-independent Effects of Statins in
Inflammation, Immunomodulation and Atherosclerosis," Current Drug
Targets. Cardiovascular and Haematological Disorders 5(2):127-134;
Sorrentino, S. and Landmesser, U. 2005. "Nonlipid-lowering Effects
of Statins," Current Treatment Options in Cardiovascular Medicine
7(6):459-466; Calabr , P. and Yeh, E. T. 2005. "The Pleiotropic
Effects of Statins," Current Opinion in Cardiology 20(6):541-546;
Davignon, J. 2004. "Atherosclerosis: Evolving Vascular Biology and
Clinical Implications. Beneficial cardiovascular pleiotropic
effects of statins," Circulation 109(23 Supplement 1):III39-III43;
Walter, D. H., Zeiher, A. M., and Dimmeler, S. 2004. "Effects of
Statins on Endothelium and Their Contribution to Neovascularization
by Mobilization of Endothelial Progenitor Cells," Coronary Artery
Disease 15(5):235-242; Walter, D. H., Rittig, K., Bahlmann, F. H.,
Kirchmair, R., Silver, M., and 5 others 2002. "Statin Therapy
Accelerates Reendothelialization: A Novel Effect Involving
Mobilization and Incorporation of Bone marrow-derived Endothelial
Progenitor Cells," Circulation 105(25):3017-3024).
[0631] That the non-LDL-Cholesterol-lowering or pleiotropic effects
of statins, to include anti-inflammatory, immunomodulatory, and
antithrombotic, may not reduce the incidence of acute events (see,
for example, Robinson, J. G., Smith, B., Maheshwari, N., and
Schrott, H. 2005. "Pleiotropic Effects of Statins: Benefit Beyond
Cholesterol Reduction? A Meta-Regression Analysis," Journal of the
American College of Cardiology 46(10):1855-1862) may not equate to
a lack of benefit for reducing inflammation leading to healing in
less severely diseased and iatrogenically affected tissue. The
benefits of statins by direct application are also addressed below
in the section entitled Cooperative Use of Impasse-jackets in Pairs
and Gradient Arrays.
[0632] Vascular endothelial growth factor (see, for example,
Asahara, T., Bauters, C., Pastore, C., Kearney, M., Rossow, S.,
Bunting, S., Ferrara, N., Symes, J. F., and Isner, J. M.1995.
"Local Delivery of Vascular Endothelial Growth Factor Accelerates
Reendothelialization and Attenuates Intimal Hyperplasia in
Balloon-injured Rat Carotid Artery," Circulation 91(11):2793-2801),
thrombospondin blockade (see Chen, D., Asahara, T., Krasinski, K.,
Witzenbichler, B., Yang, J., and 5 others 1999. "Antibody Blockade
of Thrombospondin Accelerates Reendothelialization and Reduces
Neointima Formation in Balloon-injured Rat Carotid Artery,"
Circulation 100(8):849-854), estrogen receptor alpha (see Brouchet,
L., Krust, A., Dupont, S., Chambon, P., Bayard, F., and Arnal, J.
F. 2001. "Estradiol Accelerates Reendothelialization in Mouse
Carotid Artery through Estrogen Receptor-alpha but Not Estrogen
Receptor-beta," Circulation 103(3):423-428), estrogen receptor
modulators (see, for example, Christodoulakos, G. E.,
Lambrinoudaki, I. V., and Botsis, D. C. 2006. "The Cardiovascular
Effects of Selective Estrogen Receptor Modulators," Annals of the
New York Academy of Sciences 1092:374-384; Savolainen-Peltonen, H.,
Luoto, N. M., Kangas, L., and Hayry, P. 2004. "Selective Estrogen
Receptor Modulators Prevent Neointima Formation after Vascular
Injury," Molecular and Cellular Endocrinology 227(1-2):9-20; Yue,
T. L., Vickery-Clark, L., Louden, C. S., Gu, J. L., Ma, X. L.,
Narayanan, P. K., and 6 others "Selective Estrogen Receptor
Modulator Idoxifene Inhibits Smooth Muscle Cell Proliferation,
Enhances Reendothelialization, and Inhibits Neointimal Formation in
Vivo after Vascular Injury," Circulation 2000 102(19 Supplement
3):III281-III288) and endothelial progenitor cells (see Chen L, Wu
F, Xia W H, Zhang Y Y, Xu S Y, and 5 others 2010. "CXCR4 Gene
Transfer Contributes to in Vivo Reendothelialization Capacity of
Endothelial Progenitor Cells," Cardiovascular Research
88(3):462-470) as well as other substances have been found to
expedite healing in lower mammals.
[0633] The capability for impasse-jackets, medication
ductus-intramural implants, patch-magnets, and magnet-jackets to
implement the local delivery of medication is a primary object of
the inventive system as delineated in the sections respective of
each type implant. Analogously, local and regional cancer is
treated with radiation and surgery, whereas systemic cancer is
treated by chemotherapy. The benefits of statins have been noted as
pleiotropic for the treatment of cancer as well as atheromatous
disease (see, for example, Gazzerro P, Proto M C, Gangemi G,
Malfitano A M, Ciaglia E, and 4 others. 2012. "Pharmacological
Actions of Statins: A Critical Appraisal in the Management of
Cancer," Pharmacological Reviews 64(1):102-146; Zeichner, S.,
Mihos, C. G., and Santana, O. 2012. "The Pleiotropic Effects and
Therapeutic Potential of the Hydroxy-methyl-glutaryl-CoA Reductase
Inhibitors in Malignancies: A Comprehensive Review," Journal of
Cancer Research and Therapeutics 8(2):176-183). The toxicity and
adverse side effects of chemotherapy are serious and can begin with
extravasation during infusion of a vesicant drug that leads to
tissue necrosis (see, for example, Ener, R. A., Meglathery, S. B.,
and Styler, M. 2004. "Extravasation of Systemic Hemato-oncological
Therapies," Annals of Oncology 15(6):858-862).
[0634] However, magnetized miniballs, stays, impasse-jackets, and
patch-magnets make it possible to isolate a tumor in a context of
systemic disease for receiving a high concentration of the
anticancer drug, thus allowing the systemic dose to be reduced,
while local and regional tumors can be treated by targeted
chemotherapy by means of magnetic force that allows the systemic
dose to be eliminated. Magnetically targeted chemotherapy may seek
to kill tumor cells directly--through mitotoxity, cytotoxicity,
antiangionicity, metabolic mechanism, and so on by antineoplastic
drugs otherwise delivered systemically--or indirectly, by enhancing
susceptibility of tumor cells to radiation, or both, again using
known systemic drugs for the purpose.
[0635] Implanting medication miniballs and stays to deliver a
statin or an antineoplastic drug, for example, makes it possible to
concentrate the drug or drugs within the wall surrounding a
susceptible segment, allowing a background serum level of the drug
if any, and therewith, unwanted side effects, to be reduced
accordingly, the overall reduction in the amount of the drug used
considerable. For drugs needed over a brief period to treat a
temporary condition, the sum dose that can be delivered within the
lumen wall of a more acutely affected segment by medication
miniballs or stays, whether at once or time-released, can often be
made sufficient to allow effective treatment. However, the
administration of a statin and other drugs to treat a condition
that results from a metabolic disorder, even when concentrated at
the lesion and formulated for release at a slow rate or only when
heated, will not provide a beneficial effect unless sustained
indefinitely, as is the disorder.
[0636] To deliver drugs on a sustained basis, the implants are not
used to release the drugs but rather to attract the drugs from the
passing lumen contents. The magnetized implants are placed in a
one-time invasive procedure that will allow the effective targeting
of a certain segment indefinitely, whenever the drug is taken,
preferably by mouth. The magnetically susceptible carrier-bound
drugs may be added to food for treating an esophageal neoplasm or
formulated into capsules that will release a ferrofluid which will
pass into the bloodstream to be trapped along a more severely
diseased segment of an artery. Once in the bloodstream, the
nanoparticle carrier ferrobound drug moves until it reaches the
segment that has the magnetized miniballs, stays, impasse-jackets,
stent-jackets, or magnet-wrap. To define a segment, the implants
are arranged along that segment or if the lesion is eccentric, then
according to the eccentricity, in order of increased strength of
magnetization in the antegrade direction.
[0637] A more even distribution of the drug is also obtained when
the drug carrier is likewise graduated in magnetic susceptibility.
The carrier-bound drug is then drawn from the passing blood into
the wall surrounding the segment defined for treatment. Any
residue, indeed, the entire dose, of any conventional drug that
continues past the target segment, even though concentrated for the
segment, will be so diluted as rarely if ever pose a risk of
unwanted side effects. The addition of a terminal or exit
impasse-jacket (exit-jacket) allows the release of a reversal agent
to counteract a drug so toxic or radioactive that even the diluted
residue might do harm. Such a drug will usually be an anticancer
chemotherapeutic, but might also be a drug needed to treat a
localized nematodiasistic, protozoan, mycotic, or other infection
that is resistant to conventional therapy, for example. An exit
jacket is placed and charged or loaded with the reversal agent or
counteractant first.
[0638] Since any local point of release or reversal can be
initially or subsequently affected through the application of heat,
irreversible electroporation, or by administering other substances,
the possibilities comprehended are too numerous to enumerate in any
detail. For example, different melting points or fracture
resistances to a magnetic field of the superparamagnetic magnetite
or maghemite nanoparticles or finely grained powder-including
encapsulating layer can be used to cause a prepositioned implant to
release a layer of medication. This makes it possible to release
selectable medication from a prepositioned locus in response to
diagnostic testing according to a prescribed timetable as dictated
by the course of the condition.
[0639] The overall dose of each constituent at a given interval is
determined by the number of implants placed at the site and the
concentration and rates of release of the different constituents,
the selective release of each limited only by the kinds and
intensities of energy used to release it. If noncritical and simply
accomplished, the patient can be contacted to perform the necessary
action at home. Releasing a selectable number of layers allows
controlling the dose or the specific medication or medications
according to the results of periodic diagnostic testing. Combining
separate hemispheres to make the miniballs or separate halves to
make stays doubles the absolute number of substances that might be
released from each implant and allows different substances to be
released together and simultaneously or sequentially.
[0640] Extracorporeal control over the dissolution of
medication-containing implants or side-looking syringe injector
tool-insert injectants previously introduced into a tumor or
plaque, for example, can be used to generate heat within and
thereby release an antitumor agent within or ablate a tumor (see,
for example, Thomas, C. R., Ferris, D. P., Lee, J. H., Choi, E.,
Cho, M. H., and 5 others 2010. "Noninvasive Remote-controlled
Release of Drug Molecules in Vitro Using Magnetic Actuation of
Mechanized Nanoparticles," Journal of the American Chemical Society
132(31):10623-10625; Hayashi, K., Ono, K., Suzuki, H., Sawada, M.,
Moriya, M., Sakamoto, W., and Yogo, T. 2010. "High-frequency,
Magnetic-field-Responsive Drug Release from Magnetic
Nanoparticle/Organic Hybrid Based on Hyperthermic Effect," American
Chemical Society Applied Materials and Interfaces 2(7):1903-1911;
Richter, H., Kettering, M., Wiekhorst, F., Steinhoff, U., Hilger,
I., and Trahms, L. 2010. "Magnetorelaxometry for Localization and
Quantification of Magnetic Nanoparticles for Thermal Ablation
Studies," Physics in Medicine and Biology 55(3):623-633; Hilger,
I., Hiergeist, R., Hergt, R., Winnefeld, K., Schubert, H., and
Kaiser, W. A. 2002. "Thermal Ablation of Tumors Using Magnetic
Nanoparticles: an in Vivo Feasibility Study," Investigative
Radiology 37(10):580-586; Babincova, M., Cicmanec, P Altanerova,
V., Altaner, C., and Babinec, P. 2002. "AC-magnetic Field
Controlled Drug Release from Magnetoliposomes: Design of a Method
for Site-specific Chemotherapy," Bioelectrochemistry
55(1-2):17-19).
[0641] Any of the implants and means for implanting these described
herein can be used for magnetic hyperthermia apart from the flowing
of any outer layers. Several methods for the release on command of
drugs previously implanted exist. Where the inclusion within the
implants of ferromagnetic material precludes the use of magnetic
force with distinctions in field strength as would allow either
retrieval of the intact implant or the release of a drug from
within it, externally applied heating such as with ultrasound can
be used to effect the release of therapeutic agents on a selective
basis (see, for example, Frenkel, V. 2008. "Ultrasound Mediated
Delivery of Drugs and Genes to Solid Tumors," Advanced Drug
Delivery Reviews 60(10):1193-1208; Dromi, S., Frenkel, V., Luk, A.,
Traughber, B., Angstadt, M., and 6 others 2007. "Pulsed-high
Intensity Focused Ultrasound and Low Temperature-Sensitive
Liposomes for Enhanced Targeted Drug Delivery and Antitumor
Effect," Clinical Cancer Research 13(9):2722-2727; Iga, K., Ogawa,
Y., and Toguchi, H. 1992. "Heat-induced Drug Release Rate and
Maximal Targeting Index of Thermosensitive Liposome in
Tumor-bearing Mice," Pharmaceutical Research 9(5):658-662).
[0642] Release triggering also includes activation following
placement using ultrasound (see, for example, Tachibana, K., Feril,
L. B. Jr., and Ikeda-Dantsuji, Y. 2008. "Sonodynamic Therapy,"
Ultrasonics 48(4):253-259; Staples, M., Daniel, K., Cima, M. J.,
and Langer, R. 2006. "Application of Micro- and
Nano-electromechanical Devices to Drug Delivery," Pharmaceutical
Research 23(5):847-863; Liu, Y., Miyoshi, H., and Nakamura, M.
2006. "Encapsulated Ultrasound Microbubbles: Therapeutic
Application in Drug/Gene Delivery," Journal of Controlled Release
114(1):89-99; Tachibana, K. 2004. "Emerging Technologies in
Therapeutic Ultrasound: Thermal Ablation to Gene Delivery," Human
Cell 17(1):7-15; Unger, E. C., Hersh, E., Vannan, M., Matsunaga, T.
O., and McCreery, T. 2001. "Local Drug and Gene Delivery through
Microbubbles," Progress in Cardiovascular Diseases 44(1):45-54;
Tachibana, K. and Tachibana, S. 1998. "Application of Ultrasound
Energy as a New Drug Delivery System," (in Japanese with abstract
in English at Pubmed), Nippon Rinsho [Japanese Journal of Clinical
Medicine] 56(3):584-588).
[0643] As with photosensitizer inclusive protein solder, where
adequate absorption can be achieved, a combination-form
barrel-assembly or radial projection catheter with a fiberoptic
endoscope, angioscope, or laser can be used to activate a
photosensitive ingredient (see, for example, Cheng, F. Y., Su, C.
H., Wu, P. C., and Yeh, C. S. 2010. "Multifunctional Polymeric
Nanoparticles for Combined Chemotherapeutic and Near-infrared
Photothermal Cancer Therapy in Vitro and in Vivo," Chemical
Communications 46(18):3167-3169).
[0644] 4b(2). Local Release of Drugs by Miniballs and Stays
[0645] Antiangiogenic drugs such as interferon alpha,
antiangiogenic antithrombin, angiostatin, endostatin,
vasculostatin, and so on, have two distinct applications in
connection with the implants to be described herein. The first is
for incorporation into or the coating of miniballs and stays for
subadventitial implantation at the site of an atheromatous plaque
or tumor for the purpose of inhibiting neovascularization of the
vasa vasorum. The systemic administration of such drugs typically
covers a period of months, its timing a central consideration (see,
for example, Duda, D. G. 2007. "American Association for Cancer
Research 98th Annual Meeting. Angiogenesis and Anti-angiogenesis in
Cancer," IDrugs 10(6):366-369; Goh, P. P., Sze, D. M., and
Roufogalis, B. D. 2007. "Molecular and Cellular Regulators of
Cancer Angiogenesis," Current Cancer Drug Targets 7(8):743-758; van
Kempen, L. C. and Leenders, W. P. 2006. "Tumours Can Adapt to
Anti-angiogenic Therapy Depending on the Stromal Context: Lessons
from Endothelial Cell Biology," European Journal of Cell Biology
85(2):61-68; Novak, K. 2002. "Angiogenesis Inhibitors Revised and
Revived at the AACR" [American Association for Cancer Research],
Nature Medicine 8(5):427). The controlled release of such agents
close to or at the site of the lesion with focal concentration
should allow the use of much less of the agent relative to body
mass, minimizing any side effects and reducing the cost of
treatment. Whether due to disease or normal function, where the
luminal contents are infectious or septic, stays, described below,
which are inserted from outside the ductus, are used.
[0646] Proangioangenic, neurogenic, and antineuropathic drugs with
wide application for promoting healing will more often be
associated with absorbable implants that consist solely of
medication. Growth trajectory-determining proteins have both
mitogenic and mitoinhibitory potential (see, for example, Wilson,
B. D., M., Park, K. W., Suli, A., Sorensen, L. K., and 11 other
authors, 2006. "Netrins Promote Developmental and Therapeutic
Angiogenesis," Science 313(5787):640-644; Park, K. W., Crouse, D.,
Lee, M., Karnik, S. K., Sorensen, L. K., Murphy, K. J., Kuo, C. J.,
and Li, D. Y. 2004. "The Axonal Attractant Netrin-1 is an
Angiogenic Factor," Proceedings of the National Academy of Sciences
of the United States of America 101(46):16210-16215). Local or
short path targeting, that is, placement of the implant within or
adjacent to the lesion, of oncolytic viruses (see, for example,
Kinoh, H. and Inoue, M. 2008. "New Cancer Therapy Using
Genetically-engineered Oncolytic Sendai Virus Vector," Frontiers in
Bioscience 13:2327-2334; Davydova, J., Le, L. P., Gavrikova, T.,
Wang, M., Krasnykh, V., and Yamamoto, M. 2004.
"Infectivity-enhanced Cyclooxygenase-2-based Conditionally
Replicative Adenoviruses for Esophageal Adenocarcinoma Treatment,"
Cancer Research 64(12):4319-4327) avoids systemic dispersion,
concentrates a small dose in the target tissue, minimizes the
action onset interval, or delay before the agent takes effect,
reduces systemic dispersal, and therefore the likelihood of
unwanted side-effects.
[0647] The number of implants used is one factor in determining the
local dosage. Once expended, drug-containing miniballs and stays
are fully absorbed and left in place, superparamagnetic magnetite
or maghemite nanoparticles or finely grained powder included to
allow recovery if necessary likewise dissipated. Targeted
administration should reduce the neovascularization already
undergone as an inherent result of the disease process and any
interventional measures, and where applicable, to counteract the
effect of more widely dispersed angiogenic medication. The other
application of antiangiogenic drugs is as a coating on
ferromagnetic miniballs and stays for reducing any
neovascularization following placement of a stent-jacket. The
citation of statins herein as affording benefits when locally
targeted to avoid the liver and systemic circulation is exemplary
of innumerable other drugs administered to smaller populations. Due
to the size of the population prescribed statins, the incidence of
side effects in absolute numbers is considerable despite relatively
infrequent occurrence by percent.
[0648] Drugs cited as specifically antiatherogenic in collared
hypercholesterolemic rabbits include isradipine and lacidipine
(Donetti, E., Fumagalli, R., Paoletti, R., and Soma, M. R. 1997.
"Direct Antiatherogenic Activity of Isradipine and Lacidipine on
Neointimal Lesions Induced by Perivascular Manipulation in
Rabbits," Pharmacological Research 35(5):417-422), bosentan
(Marano, G., Palazzesi, S., Bernucci, P., Grigioni, M., Formigari,
R., and Ballerini, L. 1998. "ET(A)/ET(B) Receptor Antagonist
Bosentan Inhibits Neointimal Development in Collared Carotid
Arteries of Rabbits," Life Sciences 63(18):PL259-266, TAK-044;
Reel, B., Ozkal, S., Islekel, H., Ozer, E., Oktay G, and five other
authors, 2005. "The Role of Endothelin Receptor Antagonism in
Collar-induced Intimal Thickening and Vascular Reactivity Changes
in Rabbits," Journal of Pharmacy and Pharmacology
57(12):1599-1608), the selective estrogen receptor modulator
raloxifene (Bellosta, S., Baetta, R., Canavesi, M., Comparato, C.,
and 6 others, 2007. "Raloxifene Inhibits Matrix Metalloproteinases
Expression and Activity in Macrophages and Smooth Muscle Cells,"
Pharmacological Research 56(2):160-167), and lercanidipine (Soma,
M. R., Natali, M., Donetti, E., Baetta, R., and five other authors,
1998. "Effect of Lercanidipine and Its (R)-enantiomer on
Atherosclerotic Lesions Induced in Hypercholesterolemic Rabbits,"
British Journal of Pharmacology 1998 125(7):1471-1476).
[0649] Drugs that have been cited as inhibiting atherogenesis
include, among others, bevacizumab (Stefanadis, C., Toutouzas, K.,
Stefanadi, E., Tsiamis, E., Vavuranakis, M., and Kipshidze, N.
2008. "Avastin-eluting Stent: Long-term Angiographic and Clinical
Follow-up," Hellenic Journal of Cardiology 49(3):188-90), statins
(Moulton, K. S., Heller, E., Konerding, M. A., Flynn, E., Palinski,
W., and Folkman, J. 1999. Angiogenesis Inhibitors Endostatin or
TNP-470 Reduce Intimal Neovascularization and Plaque Growth in
Apolipoprotein E-deficient Mice," Circulation 99(13):1726-1732;
Wilson, S. H., Herrmann, J., Lerman, L. O., Holmes, D. R. Jr.,
Napoli, C., Ritman, E. L., and Lerman, A. 2002. "Simvastatin
Preserves the Structure of Coronary Adventitial Vasa Vasorum in
Experimental Hypercholesterolemia Independent of Lipid Lowering,"
Circulation 105(4):415-418; Baetta, R., Camera, M., Comparato, C.,
Altana, C., Ezekowitz, M. D., and Tremoli, E. 2002. "Fluvastatin
Reduces Tissue Factor Expression and Macrophage Accumulation in
Carotid Lesions of Cholesterol-Fed Rabbits in the Absence of Lipid
Lowering," Arteriosclerosis, Thrombosis, and Vascular Biology
1;22(4):692-698) the anti-inflammatory dexamethazone (Hagihara et
al. 1991, cited above), antioxidants (see, for example, Wu, T. C.,
Chen, Y. H., Leu, H. B., Chen, Y. L., Lin, F. Y., Lin, S. J., and
Chen, J. W. 2007. "Carvedilol, a Pharmacological Antioxidant,
Inhibits Neointimal Matrix Metalloproteinase-2 and -9 in
Experimental Atherosclerosis," Free Radical Biology and Medicine
43(11):1508-1522), and/or estrogen (see Akishita, M., Ouchi, Y.,
Miyoshi, H., Kozaki, K., Inoue, S., Ishikawa, M., Eto, M., Toba,
K., and Orimo, H. 1997. "Estrogen Inhibits Cuff-induced Intimal
Thickening of Rat Femoral Artery: Effects on Migration and
Proliferation of Vascular Smooth Muscle Cells," Atherosclerosis
130(1-2):1-10). Drug miniballs and stays can release drugs in situ
and magnetized ones and impasse-jackets can be used to draw
magnetized carrier-bound drugs from the passing blood.
[0650] Selective Inhibitors of Protein Kinase C may be used to
inhibit the proliferation of smooth muscle cells (see, for example,
Tardif, J. C. 2010. "Emerging High-density Lipoprotein Infusion
Therapies: Fulfilling the Promise of Epidemiology?," Journal of
Clinical Lipidology 4(5):399-404; Newby, A. C., Lim, K., Evans, M.
A., Brindle, N. P. J., and Booth, R. F. G. 1995. "Inhibition of
Rabbit Aortic Smooth Muscle Cell Proliferation by Selective
Inhibitors of Protein Kinase C," British Journal of Pharmacology
114(8):1652-1656). More recently, apolipoprotein A-1 in a single
low dose has been cited as inhibiting acute common carotid artery
inflammation in normocholesterolemic Dow Corning Silastic.RTM.
collared rabbits (see, for example, Tardif, J. C., Heinonen, T.,
and Noble, S. 2009. "High-density Lpoprotein/Apolipoprotein A-I
Infusion Therapy," Current Atherosclerosis Reports 11(1):58-63;
Puranik, R., Bao, S., Nobecourt, E., Nicholls, S. J., Dusting, G.
J., Barter, P. J., Celermajer, D. S., and Rye, K. A. 2008. "Low
Dose Apolipoprotein A-I Rescues Carotid Arteries from Inflammation
in Vivo," Atherosclerosis 196(1):240-247; Nicholls, S. J., Dusting,
G. J., Cutri, B., Bao, S., Drummond, G. R., Rye, K. A., Barter, P.
J. 2005. "Reconstituted High-density Lipoproteins Inhibit the Acute
Pro-oxidant and Proinflammatory Vascular Changes Induced by a
Periarterial Collar in Normocholesterolemic Rabbits," Circulation
111(12):1543-1550).
[0651] The efficacy of lipoprotein A-1 for reversing
atherosclerosis in man has not been established. As an alternative
to transluminal approach, whereby miniballs are implanted
ballistically from within the lumen producing minute puncture and
trajectory wounds impelling the use of antiplatelet medication,
when the lumen would best be avoided entirely, speed is not
critical, and the anatomy and apparatus permit, stays are implanted
by extraductal approach. Miniballs can, however, include
antithrombogenic medication, usually as an outer coating.
[0652] Other substances proposed for the prevention and possible
treatment of atherosclerosis as can be mediated by segment or organ
delivery by impasse-jackets in concentrated and replenishable
dosage within circumscribed sites averting side effects include,
among others, lacidipene (Soma, M. R., Donetti, E., Seregni, R.,
Barberi, L., Fumagalli, R., Paoletti, R., and Catapano, A. L. 1996.
"Effect of Lacidipine on Fatty and Proliferative Lesions Induced in
Hypercholesterolaemic Rabbits," British Journal of Pharmacology
118(2):215-219) isradipine (Donetti, E. et al. op cit. 1997),
lercanidipine (Soma, M. R., et al. op cit. 1998), carvedilol (Wu,
T. C., Chen, Y. H., Leu, H. B., Chen, Y. L., Lin, F. Y., Lin, S.
J., and Chen, J. W. 2007. "Carvedilol, A Pharmacological
Antioxidant, Inhibits Neointimal Matrix Metalloproteinase-2 and -9
in Experimental Atherosclerosis," Free Radical Biology and Medicine
43(11):1508-1522), probucol (Donetti, E., Soma, M. R., Barberi, L.,
Paoletti, R., Fumagalli, R., Roma, P., and Catapano, A. L. 1998.
"Dual Effects of the Antioxidant Agents Probucol and Carvedilol on
Proliferative and Fatty Lesions in Hypercholesterolemic Rabbits,"
Atherosclerosis 141(1):45-51; Kuzuya, M. and Kuzuya, F. 1993.
"Probucol as An Antioxidant and Antiatherogenic Drug," Free Radical
Biology and Medicine 14(1):67-77), BO-653
(2,3-dihydro-5-hydroxy-2,2-dipentyl-4,6-di-tert-butylbenzofuran)
(Cynshi O, Kawabe Y, Suzuki T, Takashima Y, Kaise H, Nakamura M,
and 12 others 1998. "Antiatherogenic Effects of the Antioxidant
BO-653 in Three Different Animal Models," Proceedings of the
National Academy of Sciences of the United States of America
95(17):10123-10128), and gene transfer administered interleukin 10
(von der Thusen, J. H., Kuiper, J., Fekkes, M. L., de Vos, P., van
Berkel, T. J., and Biessen, E. A. 2001. "Attenuation of
Atherogenesis by Systemic and Local Adenovirus-mediated Gene
Transfer of Interleukin-10 in LDLr-/- Mice," Federation of American
Societies for Experimental Biology Journal 15(14):2730-2732).
[0653] 4b(3). Use of Drug-Releasing Ductus-Intramural Implants to
Locally Counteract or Reinforce Angiogenic or Other Systemic
Medication
[0654] The reciprocal use of drugs that are released from tiny
miniball or stay conformed implants at fixed sites to locally
inhibit or counteract the action of an injected or intravenously
infused drug that diffuses through the region has no less
potential. As with any medication or combination thereof, the
miniballs or stays can be open or closed-loop sources. The focused
use of counteractants or inhibitors to blank out or exclude a
delimited site has numerous potential applications. For example,
atherogenesis involves the elaboration of the vasa vasorum with the
proliferation of microvessels into the plaque for commensurate
perfusion and drainage as a plaque continues to develop.
[0655] Any substance in liquid or semiliquid form can also be
introduced at a preferred temperature into the lumen by
side-looking ejection syringes, or ejectors, or into the lumen wall
by side-looking injection syringes, or radial projection unit
tool-insert injectors, whether electrical/fluid system-neutral or
operated fluidically, as addressed below in the section entitled
Radial Projection Units. These disease process generated
microvessels tend to be weak and probably render the plaque more
readily susceptible to rupture or erosion. The rupture or erosion
of such a vulnerable or unstable plaque produces a breach in the
intima that prompts the formation of a thrombus, which if not the
direct cause, can nevertheless precipitate an acute cardiac event,
most often through the release of embolizing debris (see, for
example, Frink, R. J., Trowbridge, J. O., and Rooney, P. A. Jr.
1978. "Nonobstructive Coronary Thrombosis in Sudden Cardiac Death,"
American Journal of Cardiology 42(1):48-51).
[0656] Thus, in direct intramyocardial injection of an angiogenic
agent such as vascular endothelial growth factor or its genetic
precursor (see, for example, Kleiman, N. S., Patel, N. C., Allen,
K. B., Simons, M., Yla-Herttuala, S., Griffin, E., and Dzau, V. J.
2003. "Evolving Revascularization Approaches for Myocardial
Ischemia," American Journal of Cardiology 92(9B):9N-17N) to
encourage the development of collateral circulation, the ability to
place implants that release antiangiogenic medication
ductus-intramurally, that is, within the wall of an atherosclerosed
coronary artery situated at the vulnerable or unstable plaque,
makes it possible to suppress the concomitant neovascularization of
the vasa vasorum. The coexpression of a counteractant to exclude
certain targets from reaction is exhibited by malignant tumors,
which release antiangiogenic factors that suppress the growth of
metastases while releasing vascular endothelial growth factor to
stimulate the proximate formation of vessels essential for the
primary tumor to expand.
[0657] The ability to differentially eliminate a response of plaque
vasa vasora to angiogenetic agents administered to treat vascular
disease by blocking out local areas has potential value even where
surgery is uninvolved (see, for example, Yla-Herttuala, S. and
Baker, A. H. 2017. "Cardiovascular Gene Therapy: Past, Present, and
Future," Molecular Therapy 25(5):1095-1106; Stewart, D. J., Hilton,
J. D., Arnold, J. M., Gregoire, J., and sixteen other authors 2006.
"Angiogenic Gene Therapy in Patients with Nonrevascularizable
Ischemic Heart Disease: A Phase 2 Randomized, Controlled Trial of
AdVEGF(121) (AdVEGF121) [vascular endothelial growth factor
delivered in adenovirus] Versus Maximum Medical Treatment," Gene
Therapy 13(21):1503-1511; Penny, W. F. and Hammond, H. K. 2004.
"Clinical Use of Intracoronary Gene Transfer of Fibroblast Growth
Factor for Coronary Artery Disease," Current Gene Therapy
4(2):225-230; Mukherjee, D. 2004. "Current Clinical Perspectives on
Myocardial Angiogenesis," Molecular and Cellular Biochemistry
264(1-2):157-167; Freedman, S. B. 2002. "Clinical Trials of Gene
Therapy for Atherosclerotic Cardiovascular Disease," Current
Opinion in Lipidology 13(6): 653-661).
[0658] Generally, the ability to block out a circumscribed segment
of a vessel wall from uptake of a regionally diffused drug has
numerous potential applications in the gastrointestinal tract and
airway as well as in the vascular tree. In bypass graft vessels,
for example, placing angiogenic agent time-releasing implants at
the anastomoses can encourage revascularization of the graft or
grafts while other implants that release antiangiogenic agents
prevent neovascularization of the vasa vasorum of nonoperated
arteries (see, for example, George, S. J., Channon, K. M., and
Baker, A. H. 2006. "Gene Therapy and Coronary Artery Bypass
Grafting: Current Perspectives," Current Opinion in Molecular
Therapeutics 8(4):288-294). Similarly, in hybrid revascularization
combining bypass surgery with angioplasty (see, for example, Byrne,
J. G., Leacche, M., Vaughan, D. E., and Zhao, D. X. 2008. "Hybrid
Cardiovascular Procedures," Journal of the American College of
Cardiology Cardiovascular Interventions 1(5):459-468) where the use
of endothelial growth factor is favorable for the bypass but not
for the balloon dilation-stressed or stretched artery, the ability
to differentially suppress neovascularization of the vessel plaque
vasa vasora is advantageous.
[0659] Implanted perpendicularly to the longitudinal axis of the
ductus, stays do not interfere with smooth muscle function, and
nonabsorbed drug-releasing stays with a deeply textured surface
become integrated so as never to require recovery once the
medication has been expended. Miniballs of like function could also
remain. Unlike radiation seeds, which left in place, are limited to
low dose-rates or radionuclides (radioisotopes) of short half-life
such as Xenon-133 (see, for example, Sekine, T., Watanabe, S., Osa,
A., Ishioka, N., and nine other inventors, 2001. "Xenon-133
Radioactive Stent for Preventing Restenosis of Blood Vessels and a
Process for Producing the Same," U.S. Pat. No. 6,192,095),
ductus-intramurally placed stays and miniballs are practicably
recoverable and thus usable for delivering medication or radiation
in higher doses for a limited period. In more advanced disease,
external beam radiation may be essential to supplement the
radiation provided by seeds. In the irradiaton intervening tissue,
this negates the key benefit in the use of seeds over external
irradiaton or delivery through the systemic circulation by infusion
or ingestion.
[0660] In transmyocardial laser revascularization (see, for
example, Bhimji, S. 2006. "Transmyocardial Laser
Revascularization," eMedicine) performed in conjunction with
coronary artery bypass surgery (see, for example, Allen, K. B.,
Kelly, J., Borkon, A. M., Stuart, R. S., Daon, E., Pak, A. F.,
Zorn, G. L., and Haines, M. 2008. "Transmyocardial Laser
Revascularization: From Randomized Trials to Clinical Practice. A
Review of Techniques, Evidence-based Outcomes, and Future
Directions," Anesthesiology Clinics 26(3):501-519; Atluri, P.,
Panlilio, C. M., Liao, G. P., Suarez E E, and seven other authors,
2008. "Transmyocardial Revascularization to Enhance Myocardial
Vasculogenesis and Hemodynamic Function," Journal of Thoracic and
Cardiovascular Surgery 135(2):283-291; Horvath, K. A. 2008.
"Transmyocardial Laser Revascularization," Journal of Cardiac
Surgery 23(3):266-276; Spiegelstein, D., Kim, C., Zhang, Y., Li,
G., Weisel, R. D., Li, R. K., and Yau, T. M. 2007. "Combined
Transmyocardial Revascularization and Cell-based Angiogenic Gene
Therapy Increases Transplanted Cell Survival," American Journal of
Physiology. Heart and Circulatory Physiology 293(6):H3311-H3316);
Horvath, K. A., Lu, C. Y., Robert, E., Pierce, G. F., Greene, R.,
Sosnowski, B. A., and Doukas, J. 2005. "Improvement of Myocardial
Contractility in a Porcine Model of Chronic Ischemia Using a
Combined Transmyocardial Revascularization and Gene Therapy
Approach," Journal of Thoracic and Cardiovascular Surgery
129(5):1071-1077; Heilmann, C. A., Attmann, T., von Samson, P.,
Gobel, H., Marme, D., Beyersdorf, F., and Lutter, G. 2003.
"Transmyocardial Laser Revascularization Combined with Vascular
Endothelial Growth Factor 121 (VEGF121) Gene Therapy for Chronic
Myocardial Ischemia--Do the Effects Really Add Up?," European
Journal of Cardiothoracic Surgery 23(1):74-80), for example, the
direct, nondiffuse, fully contained or circumscribed if not
time-released introduction of an angiogenic agent such as matrix
metalloproteinase-9 (Johnson, C., Sung, H. J., Lessner, S. M.,
Fini, M. E., and Galis, Z. S. 2004. "Matrix Metalloproteinase-9 is
Required for Adequate Angiogenic Revascularization of Ischemic
Tissues: Potential Role in Capillary Branching," Circulation
Research 94(2):262-268) into the myocardium overlooking the left
ventricle would further encourage the formation of capillaries
about the lased channels and at the ends of the anastomoses.
[0661] Then diffusion to the vasa vasorum of the left anterior
descending coronary artery, for example (whether untreated,
angioplastied, or stented), would be avoided; however, continued
administration of angiogenic agents could be systemic, and if so,
likely to encourage further harmful expansion of the vasa vasorum
supplying the plaques of the ungrafted, unaffected, or
angioplastied arteries. The graft itself will most likely be an
internal thoracic artery, which little dependent upon a vasa
vasorum, should not require antiangiogenic implants. In this
situation, the ability to inhibit an angiogenic response locally
within the walls of the coronary arteries by prepositioning
artery-intramural implants releasing angiogenic agent inhibitor at
the sites of the vasa vasora would assist to truncate continued
atheromatous lesioning.
[0662] If the nongrafted arteries had been angioplastied, then this
procedure may itself have promoted vasal neovascularization. Were a
means found for causing the channels to remain patent (see, for
example, Krabatsch, T., Schaper, F., Leder, C., Tulsner, J.,
Thalmann, U., and Hetzer, R. 1996. "Histological Findings after
Transmyocardial Laser Revascularization," Journal of Cardiac
Surgery 11(5):326-331) if not expand into sinuses as earlier
postulated, then the epithelialization of the sinuses would likely
serve more functional perfusion. Then artery-intramural
antiangiogenic implants at the sites or potential sites of plaques
would serve to counteract the angiogenic agent or agents while
angiogenic agent releasing implants at the anastomoses of the graft
or grafts would allow local zones of reinforcement to the
angiogenic agent or agents injected or infused to promote
revascularization.
[0663] 4b(4). System Implant Magnetic Drug and Radiation
Targeting
[0664] Whether additionally coated with medication or radioactive,
for example, magnetized miniballs, stays, clasp-jackets, and all
stent-jackets, impasse-jackets, and magnet-jackets can be used to
concentrate a drug carrier particle or nanoparticle-bound drug
and/or radionuclide passing through the circulation, food or chyme
bolus, gland exudate, or urine, for example, and draw the drug
abaxially through the lumen wall into the lesion (see, for example,
Alexiou, C., Jurgons, R., Schmid, R. J., Bergemann, C., Henke, J.,
and 3 others, 2003. "Magnetic Drug Targeting--Biodistribution of
the Magnetic Carrier and the Chemotherapeutic Agent Mitoxantrone
after Locoregional Cancer Treatment," Journal of Drug Targeting
11(3):139-149; Alexiou, C., Schmid, R. J., Jurgons, R., Bergemann,
C., Arnold, W., and Parak, F. G. 2003. "Targeted Tumor Therapy with
`Magnetic Drug Targeting:` Therapeutic Efficacy of Ferrofluid Bound
Mitoxantrone," in Odenbach, S. (ed.), Ferrofluids: Magnetically
Controllable Fluids and their Applications, Lecture Notes in
Physics 594:233-251; Lubbe, A. S., Alexiou, C., and Bergemann, C.
2001. "Clinical Applications of Magnetic Drug Targeting," Journal
of Surgical Research 95(2):200-206; Alexiou, C., Arnold, W., Klein,
R. J., Parak, F. G., Hulin, P., and 4 others, 2000. "Locoregional
Cancer Treatment with Magnetic Drug Targeting," Cancer Research
60(23):6641-6648; Deleporte, A., Flamen, P., and Hendlisz, A. 2010.
"State of the Art: Radiolabeled Microspheres Treatment for Liver
Malignancies," Expert Opinion on Pharmacotherapy 11(4):579-586;
Vente, M. A., Hobbelink, M. G., van Het Schip, A. D., Zonnenberg,
B. A., and Nijsen, J. F. 2007. "Radionuclide Liver Cancer
Therapies: From Concept to Current Clinical Status," Anticancer
Agents in Medicinal Chemistry 7(4):441-459).
[0665] Medication miniballs and stays can thus release medication
within the implanted tissue or when suspended within an
impasse-jacket, as addressed below in the section entitled Concept
of the Impasse-jacket, or within a magnet-wrap, addressed below in
the section entitled Concept of the magnet-wrap, or a stent-jacket,
and highly magnetized miniballs and stays can be used to attact
drugs bound to or with magnetically susceptible carriers. The use
of magnetized ductus-intramural implants to define a segment of a
ductus for delivery of a drug or drugs is the same as described
below for impasse-jackets in the section entitled Cooperative Use
of Impasse-jackets in Pairs and Gradient Arrays and same for
magnet-wraps, which are limited to large ductus.
[0666] The drawing from the circulation of magnetically susceptible
drug carrier nanoparticles by a stent- or impasse-jacket, for
example, can be used to deliver a drug into the adluminal lesion or
simply to prevent the drug from continued travel through the
circulation. Interception of a drug before reaching the liver or
another structure or organ is one approach to minimizing adverse
drug interactions. As addressed below in the section entitled
Cooperative Use of Impasse-jackets in Pairs and Gradient Arrays,
whether through miniball or stay insertion, lumen segment
specification, or magnetic, drug-targeting allows the focused
delivery of medication into a lesion that if circulated would
indiscrimately disperse the drug throughout the entire body, allow
it to interact with other drugs and food, in all cases increasing
the risks for producing adverse side-effects.
[0667] With a systemic condition such as atherosclerosis where
certain segments are accutely affected, a statin is both circulated
and concentrated in the lesions by binding only a fraction of the
dose to magnetic dose carrier nanoparticles. Situating
progressively more strongly magnetized jackets proximadistad, or in
order of increasing strength along the bloodstream, some of the
drug is delivered to each jacket. In this way, the magnetic field
strength of any jacket is kept beneath the value that would cause
the lumen to become clogged. Equally contributing to differential
delivery when necessary, the drug carrier particles consist of a
mixture of separately preprared portions or fractions, each
differing in its magnetically susceptible content.
[0668] Magnetic marker monitoring (see, for example, Laulicht, B.,
Gidmark, N. J., Tripathi, A., and Mathiowitz, E. 2011.
"Localization of Magnetic Pills," Proceedings of the National
Academy of Sciences of the United States of America
108(6):2252-2257 Weitschies W, Blume H, Monnikes H. 2010. "Magnetic
Marker Monitoring: High Resolution Real-time Tracking of Oral Solid
Dosage Forms in the Gastrointestinal Tract," European Journal of
Pharmaceutics and Biopharmaceutics 74(1):93-101; Bergstrand, M.,
Soderlind, E., Weitschies, W., and Karlsson, M. O. 2009.
"Mechanistic Modeling of a Magnetic Marker Monitoring Study Linking
Gastrointestinal Tablet Transit, in Vivo Drug Release, and
Pharmacokinetics," Clinical Pharmacology and Therapeutics
86(1):77-83; Cora, L. A., Romeiro, F. G., Americo, M. F., Oliveira,
R. B., Baffa, O., Stelzer, M., and Miranda, J. R. 2006.
"Gastrointestinal Transit and Disintegration of Enteric Coated
Magnetic Tablets Assessed by AC Biosusceptometry," European Journal
of Pharmaceutical Sciences 27(1):1-8) makes it possible to identify
the level or levels along the gastrointestinal tract for optimal
absorption of magnetic drug-targeting ferrofluid-bonded drugs (see,
for example, Saravanan, M., Bhaskar, K., Maharajan, G., and Pillai,
K. S. 2011. "Development of Gelatin Microspheres Loaded with
Diclofenac Sodium for Intra-articular Administration" Journal of
Drug-targeting 19(2):96-103).
[0669] Optimization of these agents for absorption will make oral
administration possible (see, for example, Cai, Z., Wang, Y., Zhu,
L. J., and Liu, Z. Q. 2010. "Nanocarriers: A General Strategy for
Enhancement of Oral Bioavailability of Poorly Absorbed or
Pre-systemically Metabolized Drugs," Current Drug Metabolism
11(2):197-207; Yamanaka, Y. J. and Leong, K. W. 2008. "Engineering
Strategies to Enhance Nanoparticle-mediated Oral Delivery," Journal
of Biomaterials Science. Polymer Edition 19(12):1549-1570;
Florence, A. T. 2004. "Issues in Oral Nanoparticle Drug Carrier
Uptake and Targeting," Journal of Drug-targeting 12(2):65-70;
Florence, A. T. and Hussain, N. 2001. "Transcytosis of Nanoparticle
and Dendrimer Delivery Systems: Evolving Vistas," Advanced Drug
Delivery Reviews 50(Supplement 1):569-889; Florence, A. T. 1997.
"The Oral Absorption of Micro- and Nanoparticulates: Neither
Exceptional nor Unusual," Pharmaceutical Research 14(3):259-266;
Thomas, N. W., Jenkins, P. G., Howard, K. A., Smith, M. W.,
Lavelle, E. C., Holland, J., and Davis, S. S. 1996. "Particle
Uptake and Translocation across Epithelial Membranes," Journal of
Anatomy 189 (Part 3):487-490).
[0670] Insertion of a magnetized endoluminal stent for the purpose
of targeting drug carrier particles into a lesion or neoplasm
appears in the literature no later than 2004 (see, for example,
Chen, H., Ebner, A. D., Rosengart, A. J., Kaminski M. D., and
Ritter, J. A. 2004. "Analysis of Magnetic Drug Carrier Particle
Capture by a Magnetizable Intravascular Stent: 1. Parametric Study
with Single Wire Correlation," Journal of Magnetism and Magnetic
Materials 284:181-194; Chen, H., Ebner, A. D., Kaminski M. D.,
Rosengart, A. J., and Ritter, J. A. 2005. "Analysis of Magnetic
Drug Carrier Particle Capture by a Magnetizable Intravascular
Stent: 2: Parametric Study with Multi-wire Two-dimensional Model,"
Journal of Magnetism and Magnetic Materials 293(1): 616-632;
Aviles, M. O., Chen, H., Ebner, A. D., Rosengart, A. J., Kaminski,
M. D., and Ritter, J. A. 2007. "In Vitro Study of Ferromagnetic
Stents for Implant Assisted-magnetic Drug-targeting," Journal of
Magnetism and Magnetic Materials 311(1):306-311, Proceedings of the
Sixth International Conference on the Scientific and Clinical
Applications of Magnetic Carriers).
[0671] While entailing a minor surgical procedure, an extraluminal
magnetic stent or impasse-jacket as described herein leaves the
lumen clear, the stent not within the lumen so that it attracts the
drug carrier nanoparticle-bound drug to itself but rather draws the
drug into the lesion or neoplasm, and can usually occupy the
spatial volume needed to bring far greater local field intensity
than the endoluminal space would allow (see, for example, Polyak,
B. and Friedman, G. 2009. "Magnetic Targeting for Site-specific
Drug Delivery: Applications and Clinical Potential," Expert Opinion
on Drug Delivery 6(1):53-70, also cited above in the section
entitled Concept of the Impasse-jacket and that below entitled
Interception and Recovery of a Miniball Entering the
Circulation).
[0672] By comparison, an endoluminal paclitaxel eluting stent
allows the blood to wash away some of the drug. With a magnetized
implant such as an impasse-jacket, magnet-wrap, patch-magnet, or
magnetized miniball, stay or array thereof positioned to target the
treatment site, ingestible drugs formulated for such use in the
vascular tree will free magnetic drug-targeting from the need for
an external magnet or magnets and therewith, the clinic. Other
routes for vascular or other system ductus delivery amenable to
self-admnistration are subcutaneously implanted direct and central
catheter access injection and/or infusion portals. Then, while to
emplace a patch-magnet, stent-jacket, or impasse-jacket, for
example, will involve a minor surgical procedure, once
accomplished, it will be possible to administer a magnetically
targetable drug by mouth that on circulating, will be drawn from
the bloodstream to the lesion or neoplasm targeted.
[0673] In single stage magnetic drug-targeting, a magnetized collar
such as a stent- or impasse-jacket is placed in encircling relation
to the segment of an artery to be treated, for example. Since the
jacket is placed circumadventitially, it draws the ferromagnetic or
superparamagnetic drug carrier nanoparticules, for example, into
the lesion in the wall of the artery, not to an in the way
endoluminal stent. The latter blocks the further passage of the
drug into the lesion and is too limited in available space to
generate a high gradient local field.
[0674] In dual or 2-stage magnetic drug-targeting as an example of
multistage magnetic drug-targeting, a first extraluminal intrinsic
motion compliant stent or impasse-jacket assists to draw the orally
administered drug with carrier nanoparticles toward the villi of an
optimal segment of the gastrointestinal tract for passage into the
bloodstream (see, for example, Cherry, E. M., Maxim, P. G., and
Eaton, J. K. 2010. "Particle Size, Magnetic Field, and Blood
Velocity Effects on Particle Retention in Magnetic Drug-targeting,"
Medical Physics 37(1):175-182; Shaw, S. and Murthy, P. V. S. N.
2010. "Magnetic Drug-targeting in the Permeable Blood Vessel--The
Effect of Blood Rheology," Journal of Nanotechnology in Engineering
and Medicine 1(2):021001-021012; Cheng, J., Teply, B. A., Yoon
Jeong, S., Yim, C. H., Ho, D., Sherifi, I., and 4 others, 2006.
"Magnetically Responsive Polymeric Microparticles for Oral Delivery
of Protein Drugs," Pharmaceutical Research 23(3):557-564; des
Rieux, A., Fievez, V., Garinot, M., Schneider, Y. J., and Preat, V.
2006 "Nanoparticles as Potential Oral Delivery Systems of Proteins
and Vaccines: A Mechanistic Approach," Journal of Controlled
Release 116(1):1-27; Ito, R., Machida, Y., Sannan, T., and Nagai,
T. 1990. "Magnetic Granules: A Novel System for Specific Drug
Delivery to Esophageal Mucosa in Oral Administration,"
International Journal of Pharmaceutics 61(1-2): 109-117), and a
second such implant placed about the target segment along the
ductus draws the nanoparticles into the lesion or neoplasm.
[0675] The first implant does not allow passage through the villi
that the chemistry and shape of the nanoparticles would disallow or
disfavor but rather accelerates the congregation over the villi
surfaces of the particles and prevents the loss of particles by
continued passage through the gastrointestinal tract. Similarly, a
duct, artery, or vein of a gland or organ can be collared with an
extraluminal magnetic stent-jacket, impasse-jacket, or magnet-wrap
(magnet-jacket) to target a hormone, enzyme, or the section
associated with that structure. The avoidance of clogging or
embolization is achieved by administration in sub-embolic doses.
Nonmetallic stent-jackets and impasse-jackets are nonabsorbable;
limited-term administration of such medication may use an
absorbable jacket as addressed below in the sections on stent and
impasse-jackets.
[0676] Significantly, stent-jacket, impasse-jackets, and
magnet-jackets can all be used to draw and concentrate magnetic
drug carrier particles, which most often will be moving through the
blood vessel these encircle even though havng been implanted with
no forethought as to such use. The multimodal potential offered by
nanotubules, nanoparticles, and microspheres containing iron oxide
or magnetically susceptible metals (cobalt, iron, or cobalt-iron)
for concurrent nanoimaging, magnetic drug-targeting, and
extracorporeal or remote heat induction applies to miniballs,
stays, and the other implants described herein. Extracorporeal
heatability in turn enables the release or accelerated release of a
drug from a drug eluting or drug coated implant, or accelerated
uptake of a drug or increased rate of chemical action of a
therapeutic substance in the tissue treated.
[0677] Heating a miniball or stay, for example, can be used to
accelerate the denaturing of a proteinaceous coating such as a
tissue solder or the initial setting or curing of a surgical
adhesive, for example. Miniballs can implant and radial projection
unit side-looking injection tool-inserts can inject medication
ductus-intramurally independently of magnetic force, and as
addressed below in the section entitled Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays, impasse-jackets can
be paired as entry and exit jackets to stipulate the starting and
stopping points (levels) for exposure of the lumen to a drug. These
techniques allow the local release or the extraction and
accumulation from the circulation of a drug or drugs that if
circulated would be toxic. Statins are used as exemplary of closely
targeted drug delivery, because of the prevalence of arterial
disease; virtually every therapeutic substance poses a risk of
unwanted side effects if allowed access to the tissue susceptible
thus.
[0678] Magnetic drug and/or radioisotope (radionuclide) targeting
can compensate for or eliminate the requirement for the intrinsic
affinity or normal uptake of the drug or therapeutic substance by
the target organ or tissue such as radiolabeled iodine by the
thyroid gland. Other examples that might be cited are the systemic
administration of bevacizumab to target endoglin, thereby to
suppress angiogenesis in colon and lung cancer (Wood, L. M., Pan,
Z. K., Guirnalda, P., Tsai, P., Seavey, M., and Paterson, Y. 2011.
"Targeting Tumor Vasculature with Novel Listeria-based Vaccines
Directed against CD105," Cancer Immunolology and Immunotherapy
60(7):931-942), and the use of Listeria-based vaccines to target
breast cancer (Kim, S. H., Castro, F., Paterson, Y., and Gravekamp,
C. 2009. "High Efficacy of a Listeria-based Vaccine against
Metastatic Breast Cancer Reveals a Dual Mode of Action," Cancer
Research 69(14) :5860-5866).
[0679] That an impasse-jacket will stop any magnetically
susceptible matter regardless of its chemistry or physiological
association means that drugs and/or others pharmaceuticals or
therapeutic substances can be delivered to it in any combination in
any sequence. Varying the susceptible content of the miniball
and/or the strength of magnetization of successive impasse-jackets
allows some measure of direction to one of several impasse-jackets
when present; however, multiple jackets are reliably addressed by
direct injection. Until means for the oral administration of the
substance or load intended for delivery to a given jacket are
available, Impasse-jackets used at the inlet and outlet of a
luminal segment, organ, or gland that necessitate frequent dosing
will require a lead-in catheter with injection portal at the body
surface. Application to the thyroid gland is briefly mentioned in
the sections below entitled Stent-jackets and Stent-jacket
Supportng Elements: Structural and Functional Considerations and
Subcutaneous, Suprapleural, and Other Organ-attachable Clasp- or
Patch-magnets.
[0680] Radionuclide carrier nanoparticles or microspheres, for
example, can be introduced by infusion or injection upstream from a
stent-, impasse-, magnet-jacket, or patch-magnet, for example, to
be drawn from the passing blood up against and into the lesion.
Clasp- or patch-magnets applied to the surface of an organ can be
used to draw drug carrier nanoparticles from the blood. This
brute-force approach can be used to deliver antineoplastic drugs to
the affected organ with or without matter for concurrent or
subsequent radiofrequency hyperthermia or thermablation. This
differs from the metabolic targeting of an organ to deliver
radiofrequency heatable particles in necessitating a preliminary
invasive procedure to place the magnetic implants, which can,
however, be made to disintegrate without necessitating a second
procedure to remove it.
[0681] By comparison, metabolic targeting is completely
noninvasive, but dependent upon the development of substances
naturally drawn to the target organ (see, for example, Kennedy, L.
C., Bickford, L. R., Lewinski, N. A., Coughlin, A. J., Hu, Y., Day,
E. S., West, J. L., and Drezek, R. A. 2011. "A New Era for Cancer
Treatment: Gold-nanoparticle-mediated Thermal Therapies," Small
7(2):169-183; Cherukuri, P. and Curley, S. A. 2010. "Use of
Nanoparticles for Targeted, Noninvasive Thermal Destruction of
Malignant Cells," Methods in Molecular Biology 624:359-373;
Cherukuri, P., Glazer, E. S., and Curley, S. A. 2010. "Targeted
Hyperthermia Using Metal Nanoparticles," Advanced Drug Delivery
Reviews 62(3):339-345; Cardinal, J., Klune, J. R., Chory, E.,
Jeyabalan, G., Kanzius, J. S., Nalesnik, M., and Geller, D. A.
2008. "Non-invasive Radiofrequency Ablation of Cancer Targeted by
Gold Nanoparticles," Surgery 144(2):125-132; Curley, S. A.,
Cherukuri, P., Briggs, K., Patra, C. R., Upton, M., Dolson, E., and
Mukherjee, P. 2008. "Noninvasive Radiofrequency Field-induced
Hyperthermic Cytotoxicity in Human Cancer Cells Using
Cetuximab-targeted Gold Nanoparticles," Journal of Experimental
Therapeutics and Oncology 7(4):313-326; Gannon, C. J., Cherukuri,
P., Yakobson, B. I., Cognet, L., Kanzius, J. S., Kittrell, C.,
Weisman, B., Pasquali, M., Schmidt, H. K., Smalley, R. E., and
Curley, S. A. 2007. "Carbon Nanotube-enhanced Thermal Destruction
of Cancer Cells in a Noninvasive Radiofrequency Field," Cancer
110(12):2654-2665; Klune, J. R., Jeyabalan, G., Chory, E., Kanzius,
J. S., and Geller, D. A. 2007. "Pilot Investigation of a New
Instrument for Non-invasive Radiowave Ablation of Cancer," Journal
of Surgical Research 137:263).
[0682] Seed and irradiated stays or miniballs implanted within or
close to the lesion ab initio can emit radiation as well. Except
for those with a punched (perforated) base-tube, a stent-jacket can
provide not only the magnetic field for use with an implant or an
injected or infused drug and/or radioisotope-bound
nanoparticle-containing ferrofluid, for example, but can be coated
with tissue-isolating radiation shielding. The shielding, to which
body tissues will be exposed if incorporated into the absorbable
matrix of an absorbable stent-jacket, for example, once dissipated,
can consist of an overlapping gold or platinum particulate. Other
shielding materials, tungsten, iridium, and osmium, are toxic and
require nonabsorbable encapsulation for chemical isolation such as
with gold.
[0683] Bioabsorbable polymers are numerous and addressed below in
the section entitled Absorbable Base-tube and Stent-jacket,
Miniball, Stay, and Clasp-magnet Matrix Materials. To allow
addition to any preexisting stent-jacket, the shielding is glued to
the outer surface of the stent-jacket as an elastic polymeric
matrix layer containing one or a combination of the foregoing
materials embedded as an overlapping particulate. If the
stent-jacket is absorbable, then the matrix of the shield layer is
absorbable as well. Unlike gold compounds administered orally in
the form of a powder, residual elemental gold or platinum are not
absorbed and not toxic. If an absolute amount of a potentially
toxic particulate is used in an absorbable implant such as a
stent-jacket, then it is chemically isolated by nonabsorbable
encapsulation, metallic or polymeric.
[0684] If the use of large or multiple absorbable shielded stents
pose the risk of toxicity and the particulate is not to remain as a
residue but be absorbed at a rate subtoxic for the specific
substance, then different thicknesses of a shield
particle-encapsulating coating polymer and/or polymers with
different rates of absorption are used to stage dissolution in
fractions. The same measures pertain to the dissipation of
ferromagnetic particulate embedded in an absorbable stent-jacket,
which if iron must be controlled in rate and if sintered lanthanoid
must be permanently encapsulate, as addressed below in the section
entitled Absorbable Base-tube and Stent-jacket, Miniball, Stay, and
Clasp-magnet Matrix Materials. Within the size constraints imposed,
plastic radiation barriers do not afford adequate shielding.
Radiation shielding for higher dose-rate emissive material is also
addressed below in the section entitled Stent-jackets and
Stent-jacket Supportng Elements.
[0685] The thickness of the shielding layer applied to the
base-tube is varied in proportion to the level of radiation to be
shielded up to the point where pliancy sufficient to comply with
the intrinsic action in the substrate ductus is significantly
degraded. An impasse-jacket encircles the ductus in a magnetized
grid that allows the use of a powerful external (extracorporeal)
electromagnet to extract a trapped miniball or any magnetically
susceptible residue. Where circumductal space is inadequate, the
fine gauge and round contour of the wires of the extraction grid,
both of which factors may militate against achieving the required
field strength to stop a passing microsphere or nanoparticle
containing magnetically susceptible matter when intrinsically
magnetized, even with a magnetized coating, a chemical
isolation-encapsulated neodymium bar magnetized normal to the lumen
axis is fused or bonded to the exterior surface of the grid in long
coaxial relation and aside from the potential extraction path.
[0686] If necessary, more distant but more powerful patch-magnets
can also be placed with magnetic field oriented perpendicularly to
the jacket. Like stent-jackets, impasse and magnet-jackets can also
include some tissue surrounding the ductus. For stenting, this
allows the use of a tissue hardener to allow placing the
intravascular component of the extraluminal stent or
ductus-intramural implants (miniballs or stays) when the wall of
the ductus is too thin to be implanted or too weak to withstand the
tractive force applied to the ductus-intramural implants to open
the lumen. Unless a stent-jacket is absorbable so that an
underlying extraction grid will be exposed upon its dissolution, it
cannot, as does an impasse-jacket, allow a suspended miniball to be
noninvasively extracted, but can incorporate radiation
shielding.
[0687] High dose-rate stays, or seed-stays, and the shield-jacket
or shielded stent-jacket are placed and removed through the same
local percutaneous incision, so that even though the stays must be
inserted first, the time other tissue is exposed to the radiation
is slight. Since the radiation shield-jacket or shielded
stent-jacket encloses the stays, removal of the stays would
ordinarily require that the jacket be removed first;. However, the
need for recovery is avoided by using an absorbable shield and
absorbable stays, of which the toxic shielding particles, usually
tungsten, are encapsulated in gold. Radiation shielded
stent-jackets can be incorporated into a chain with any other type
stent or impasse-jackets where each jacket is selected to treat the
segment it encircles.
[0688] When miniballs, placement requires triple access,
transluminal for the miniballs, through a local incision for the
local shielding stent-jacket, and another incision to place a
second shielded stent-jacket or impasse-jacket with absorbable
shield downstream to trap any miniball that accidentally enters the
bloodstream. The latter is placed first, the local shielding jacket
second, and the miniballs last. Reasons for placing the jacket
first, primarily to serve as a barrier to protect against a
perforation or radiation on discharge, are addressed below in the
section entitled Sequence of Stent-jacket Placement and
Implantation. A nonabsorbable local stent-jacket with a radiation
shield can be left in place after nonabsorbable seed miniballs have
recovered with the tractive electromagnets in the muzzle-head.
[0689] When not supported by a downstream external electromagnet to
arrest and extract a miniball and/or impasse trap-jacket that
accidently enters the circulation, radiation shield-jackets and
seed miniballs contain sufficient ferrous matter to assure that the
miniballs will remain fixed in place without exerting deflective
force on the muzzle-head. Thus, while radiation or seed miniballs
that are encapsulated in gold need never be removed, local and
usually downstream jackets are still placed for shielding and for
positional security. Nonabsorble radiation shield-jackets and
shielded stent-jackets can likewise be left in place, or
alternatively, these jackets can be made to be absorbed.
[0690] Inasmuch as noninvasive extraction necessitates an
uninterrupted path from the adventitia to the extraction end-point
outside the ductus or to the exterior, an impasse-jacket provides
an extraction grid of fine wire strongly magnetized at a strength
normal to the longitudinal axis that drops off moving away to
either side from the center. In an impasse-jacket to serve as a
trap-jacket, the strength of magnetization about the circumference
may be uniform, or to favor attraction to the arc closer to the
body surface through which a prospective extraction would be
performed, eccentric. Similarly, in impasse-jackets to draw
medication from the passing luminal contents, the strength of
magnetization is eccentric according to the arcuate distribution of
the lesion targeted. A radiation shield, however, must be
continuous, so that when the shield is nonabsorbable, the
requirements for radiation shielding and extractability directly
conflict.
[0691] For this reason, the radiation shield is usually made to
break up after the radiation has become depleted or is made
noninvasively destructible on demand through the inclusion of
continuous ferrous matter to allow magnetic or electromagnetic heat
induction, as addressed above in the sections entitled Field of the
Invention and Implants that Radiate Heat On Demand, among others
Destruction thus requires that the shield layer incorporate
sufficient continuous ferrous matter to allow noninvasive
dissolution by magnetic or electromagnetic heat induction. An
absorbable stent-jacket can incorporate an extraction grid, but
practical extraction grids must usually be made of magnetizable
stainless steel, which unlike magnesium, for example, is not
absorbable.
[0692] To avoid tunical delamination or pull-through or the
extraction of the ductus-intramural implants through the
adventitia, stent-jackets should exert the least magnetic tractive
force, whereas impasse-jackets must provide sufficient force to
extract relatively low susceptibility particles, for example.
Neodymium magnets should not demagnetize over time as to
necessitate compensatory overmagnetization for use in the very
young. If after decades this becomes a concern, the stent-jacket
should be recovered and replaced. Thus, stent-jackets but not
impasse-jackets, which are devised to allow extraction out the
sides, can be shielded. To strengthen the tractive force, the gauge
of the grid wire in an impasse-jacket must be increased.
[0693] An impasse-jacket of this kind can also serve as a
stent-jacket only so long as this increase does not significantly
affect its compliance with the action in the ductus. That requires
dispensing with an intrinsically flexible base-tube and instead
using spring hinges as used in impasse-jackets generally. Where
injury to the surrounding tissue is not a concern, such as when the
segment treated extends past the jacket margins and the lesion is
thick enough to absorb the radiation, an impasse-jacket can be used
with high dose-rate miniballs to expedite extraction following
short-term exposure. However, it is not able to provide shielding.
Depending upon the surrounding anatomy, retrieval can be
conventional through the grid with the use of a high power external
electromagnet or transluminal using the recovery electromagnets in
the barrel-assembly muzzle-head.
[0694] Shielding is, however, compatible with the application of a
high intensity radiofrequency alternating magnetic field for the
purpose of heating implants containing ferrous and/or
cobalt-chromium alloy matter, for example, encircled within the
shielded stent-jacket to accelerate the release and/or uptake of a
drug applied as a coating to miniballs, for example, as addressed
below in the section entitled Extracorporeal Energization of
Intrinsic Means for Radiating Heat from within Medication Implants
and Medication and/or the Tissue bonding-Coatings of Implants.
Unless exceptionally the stent-jacket has been placed solely to
attract and shield against radiation emitting matter for a limited
time after which it is intended to be removed, the incorporation of
a shielding layer or layers in the base-tube is practicably
incompatible with direct extraction.
[0695] Instead, the recovery electromagnets in a barrel-assembly
would have to extract the implants endoluminally, requiring
reentry. An impasse-jacket is configured to allow radially outward
extraction of a miniball from within the lumen to the exterior with
the aid of an extracorporeal electromagnet and cannot be
continuously shielded over any portion of the circumference
essential for extraction. Because it still presents obstructive
areas at the surface, even a stent-jacket without a continuous
layer of shielding and having a punched base-tube is unsuited to
the direct extraction of miniballs or carrier nanoparticles.
[0696] 4b(5). Circulating Drug-Blocking and Drug Interaction
Avoidance
[0697] Drug-targeting through local release and uptake not only
focuses drug delivery in the diseased tissue, but by substantially
withholding the drug from the circulation, minimizes the potential
for adverse interactions with any other drug or nutrient in the
circulation. Reciprocally, an unpaired impasse-jacket, for example,
can be positioned to remove a drug from the circulation thereby
preventing a lesion or structure from exposure to that drug.
Provided the substances essential are available, a segment of an
artery, the liver, or a kidney, for example, can be targeted for
receiving or for not receiving a drug, for example.
[0698] Removal can be through the release of a second substance
such as by the infusion, injection, or injection of a third
substance and/or heat that reverrses, counteracts, or neutralizes
the first or by extracting the first substance by the magnetic
field of the magnetized miniball, stay, array thereof, impasse-,
stent-, or magnet-jacket, or patch-magnet. The avoidance of adverse
side effects and drug-drug interactions is addressed above in the
section entitled Field of the Invention and below in the section
entitled Cooperative Use of Impasse-jackets in Pairs and Gradient
arrays, among others.
[0699] Magnetic drug carrier nanoparticles used to treat lesions in
the lumen wall are ferrobound so that upon release from a miniball
suspended in the lumen by an impasse-jacket, for example, upon
dissolution by the passing blood, infusion of another substance,
and/or the application of heat, the drug is drawn by the
magnetically susceptible component against the lumen wall and into
the lesion. By contrast, particles used to treat organs can be
ferro co-bound so that only the susceptible component of or
enclosed with the particles are drawn to the impasse-jacket, while
the drug or radionuclide is carried forward in the bloodstream, for
example, into the target organ.
[0700] A second impasse-jacket at the end of the treatment segment
or target organ can release a reversal or neutralizing substance,
whether released by the first substance or another chemical or an
enzyme. The ability to selectively pass and prevent certain drugs
from continued passage to or from the liver in particular has
profound drug interaction implications. If the dose is large enough
to risk clogging an impasse- or stent-jacket, for example, then
successive jackets along the artery, for example, are positioned in
order of increasing field strength for the expected range in blood
pressure.
[0701] The field strength produced by the jackets must also take
the blood pressure, velocity, and posture into account (see, for
example, Cherry, E. M., Maxim, P. G., and Eaton, J. K. 2010, op
cit; Haverkort, J. W., Kenjeres, S., and Kleijn, C. R. 2009.
"Computational Simulations of Magnetic Particle Capture in Arterial
Flows," Annals of Biomedical Engineering 37(12):2436-2448).
Magnetic drug-targeting, for example, is addressed above in the
section entitled Drug-targeting Miniballs and Stays and below in
the sections entitled Concept of the Impasse-jacket and Miniball
and Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets, among others.
[0702] That drugs posing a risk to a certain organ or lesion can be
prevented from reaching that part where drug interaction is
uninvolved is obvious. The blocking of a particular organ or
luminal lesion from exposure to a drug in the circulation by
removing the drug before it reaches that structure pertains to
larger lumina and structures so that where the drug is not
re-released past the structure, collateral circulation should still
deliver the drug past that blocked out. Adverse interaction
avoidance is pertinent whether the drugs are to treat the same
condition, the condition is ductus situated, to treat independent
and unrelated (trans-nosological), or interactive (trans-syndromal)
comorbidity (see, for example, McCarthy, C., Clyne, B., Corrigan,
D., Boland, F., Wallace, E., and 5 others 2017. "Supporting
Prescribing in Older People with Multimorbidity and Significant
Polypharmacy in Primary Care (SPPiRE): A Cluster Randomised
Controlled Trial Protocol and Pilot," Implementation Science
12(1):99; Stokes, J., Kristensen, S. R., Checkland, K.,
Cheraghi-Sohi, S., and Bower, P. 2017. "Does the Impact of Case
Management Vary in Different Subgroups of Multimorbidity? Secondary
Analysis of a Quasi-experiment," BioMed Central Health Services
Research 17(1):521; Smith, S. M., Wallace, E., O'Dowd, T., and
Fortin, M. 2016. "Interventions for Improving Outcomes in Patients
with Multimorbidity in Primary Care and Community Settings,"
Cochrane Database of Systatic Reviews 3:CD006560; Valderas, J. M.,
Starfield, B., Sibbald, B., Salisbury, C., and Roland, M. 2009.
"Defining Comorbidity: Implications for Understanding Health and
Health Services," Annals of Family Medicine 7(4):357-363). Care in
comorbidity may differ in a system of socialized medicine (see, for
example, Meranius, M. S. and Josefsson, K. 2017. "Health and Social
Care Management for Older Adults with Multimorbidity: A
Multiperspective Approach," Scandinavian Journal of Caring Sciences
31(1):96-103).
[0703] The risk of rhabdomyolysis when both statins and fibrates
and/or niacin are administered, for example, is addressed below in
the section entitled Cooperative Use of Impasse-jackets in Pairs
and Gradient Arrays. Numerous methods are provided herein for
accelerating uptake, to include drug carrier nanoparticles that
allow not only drawing the drug toward an impasse-jacket
surrounding the lesioned segment, for example, but also allow the
medication to be heated with the aid of a high intensity
alternating magnetic field, as addressed in in the section below
entitled System Implant Magnetic Drug and Radiation Targeting,
among others. Unlike a radio frequency alternating magnetic field,
high intensity focused ultrasound directly heats tissue rather than
a target containing ferrous or titanium matter implanted within the
tissue.
[0704] 4b(6). Drug-Targeting Miniballs and Stays
[0705] Miniballs and stays that generate a magnetic field of the
required strength can be used to attract magnetic drug and/or
radionuclide carrier nanopaticles, microspheres, or miniballs
containing such particles from the passing luminal contents. This
is especially valuable along the bloodstream, but also along a
peristaltic ductus such as the digestive tract, where an
endoluminal stent fails to comply with if not resists peristalsis,
and usually causes significant chronic irritation at the margins.
An endoluminal stent is also likely to have too little space to
include sufficient magnetic material and draws the drug carrier
particles to itself, obstructing and thus minimizing if not
preventing delivery to the target tissue behind (outside, beyond,
surrounding) it.
[0706] A holding impasse-jacket can be used, for example, to
preposition a smart pill by suspension within the circulation for
response to a programmed condition of blood chemistry should such
arise, without the need for monitoring. Unlike those suspended in
the bloodstream by means of impasse-jackets, addressed below in the
section entitled Concept of the Impasse-jacket, miniballs and stays
used without a holding jacket must be implanted
ductus-intramurally. Magnetized stays and miniballs can be used in
multistage drug targeting where the other components placed at
intervals along the lumen are impasse-jackets or patch-magnets, for
example.
[0707] Other sections herein pertaining to this include, in order,
System Implant Magnetic Drug and Radiation Targeting, Circulating
Drug Blocking and Drug Interaction Avoidance, Endoluminal
Prehension of Miniballs and Ferrofluids, Concept of the
Impasse-jacket, Uses of Impasse-jackets, Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays, and Chemical Control
over Implants and Coated Implants, to Include Miniballs, Stays, and
Prongs. To achieve the least weight and size that will be fully
dependable; neodyimium iron boron, that material currently known
with the highest energy product, or magnetic field strength per
unit mass, is incorporated, usually as a continuous core.
[0708] This material toxic and an outer layer aiding to produce a
deeply textured surface, magnetized miniballs and stays are
biocompatibly coated by plating, Microfusion.RTM., as addressed
below in the section entitled Stent-jackets and Stent-jacket
Supporting Elements, or polymeric encapsulation. Except for a
coating of surgical cement, the space constraints will usually
disallow any significant outer layering with medication. All
miniballs and stays for retentive infiltration by the surrounding
tisssue are given a deeply textured surface which also helps to
retain any cement used and gradually replaced by the tissue. Once a
miniball with deep surface texture becomes infiltrated with tissue,
an impasse-jacket allows its extraction with the aid of an external
electromagnet; otherwise, such miniballs should be left in place.
If a need for resonance imaging arises, the miniball is extracted
by means of a sudden pulse from a powerful external
electromagnet.
[0709] Magnetized miniballs are oriented to be attracted by, that
is, for opposite polarity to, an external electromagnet as might
later be needed to extract these. Immediately after placement, an
external magnet is used to orient the miniball or miniballs before
the surrounding cellular exudate has the time to congeal, or
coagulate. All but the largest stays are magnetized along their
average or implied long axis, so that attractants are drawn to
their tips. Such stays can also incorporate separate magnets toward
the tips. Longitudinally extended and allowing some clearance from
the outer surface of the ductus, a magnetized collar or
extraluminal stent, whether an impasse-jacket or a stent-jacket
with tiny magnets mounted about its outer surface, does not have
the flexibility to conform to the passing constrictive wave as the
outer surface of the gut, for example, is drawn inward (centrally)
away from the collar.
[0710] Although the stent-jacket base-tube or the impasse-jacket
wire mesh does not conform to the inward or central excursion of
peristalsis, it does comply with any outward excursion and is
therefore nonconstrictive. The increase in field strength required
to keep the susceptible matter within range due to wall recession
as the wave passes is insignificant even for the treatment of
Crohn's disease, much less esophageal cancer. For nonadvanced
regional enteritis, it can be significant. In critical contrast to
an extraluminal stent, an endoluminal stent draws drug/or
radionuclide carrier particles entirely through the lumen wall;
however, the abluminal tractive reach limited by the force exerts,
a magnetized miniball or stay does not draw carrier particles
beyond (radially outward from) its own position as would an
impasse-jacket that encircled the ductus.
[0711] For intramural delivery, the drug carrier particles or
microspheres are formulated for quick dissolution and release,
whereas for delivery beyond the stent requires a fraction or a
separate dose formulated for delayed release. If disease would
spread from the outer surface of the gut to the mesentery (The
Merck Manual of Diagnosis and Therapy, 18th Edition, 2006, Section
2, Gastrointestinal Disorders, Section 18, "Inflammatory Bowel
Disease," page 152), for example, an extraluminal chain-stent,
because it substantially surrounds the lesion, reduces access of
the disease to healthy tissue outside the stent. With respect to
the Crohn's example mentioned in the section above entitled Field
of the Invention, extraintestinal symptoms resulting from the
spread of disease from the gut are restrained, but not symptoms
that appear separately.
[0712] The systemic medication necessary to suppress the separate
symptoms should be less. As any magnetic drug carrier particle
attractor, intravascular, miniballs and stays draw carrier
particles up to the radial distance at which these are infixed but
then obstruct the drug and/or radionuclide from being drawn beyond
itself to the exterior surface of the ductus, much less beyond. So
long as disease is confined to portions of the ductus adluminal to
the miniballs or stays, drug-targeting magnetic miniballs or stays
should suffice for medical management. Here too, either an initial
nonmagnetic coating or delayed dissolution and release of the
magnetic carrier bound drug allows the delivery of the drug or
drugs radially outward from the stay or miniball as the target.
Disease that is transmural, that is, which has progressed to
involve the ductus wall through and through justifies the addition
of an extraluminal stent through a small laparoscopic entry portal
local to the lesion.
[0713] Miniballs should be marked to indicate the north pole, and
the magnetic orientation of intraluminal and extralumal implants
should be coordinated. In the gut, the barrel-assembly is
introduced rectally as is an endoscope with no incision involved.
Individual drug-targeting stays are placed laparoscopically with a
suitable pliars-configured or stay insertion tool as described
below in the section of like title. Miniballs and stays have no
significant longitudinal extension, so that used in a peristaltic
ductus, whether the gut, a ureter, or gamete tube, both comply with
the passing wave while drawing magnetically susceptible matter from
the passing lumen contents, but except as indicated above, no
farther radially than their own position. Miniballs and stays that
are dropped are readily recovered with the immediately present tool
that is used to place these, that is, the recovery electromagnets
in the barrel-assembly muzzle-head or the stay insertion tool, or a
magnet-tipped catheter, or probe.
[0714] Magnetized miniballs and stays coated with an initial dose
to treat the abluminal portions of the ductus or achieve good
concentration at the treatment site immediately can be left in
place and thereafter used to attract subsequent doses whenever
administered, whether by infusion, injection, or ingestion. A
multiple radial discharge barrel-assembly with the recovery
electromagnets momentarily switched off driven by a linear
positioning stage can place miniballs in a close or high density
formation to concentrate the substance or substances drawn into a
lesion having longitudinal extension. Using miniballs, an external
electromagnet is used to align the field of each before the landing
point of each has had the opportunity to coagulate or congeal.
Asymmetrical, the fields of stays spontaneously align.
[0715] 4c. Implants that Radiate Heat on Demand
[0716] Implants, to include those ductus-intramural, or miniballs
and stays, containing continuous ferromagnetic material such as in
the form of encapsulated plates can be heated by placing the
patient in a radiofrequency alternating magnetic or electromagnetic
field, the temperature noninvasively monitored by means of an
equivalent temperature-calibrated eddy current detector. While more
pertinent to stent-jackets, ductus-intramural implants that radiate
heat on demand from outside the body can also be used for
hyperthermic therapy, to apply followup thermoplasty to
noninvasively debulk postprocedural hyperplasia, accelerate the
dissolution and/or uptake of drugs at the implant site, initiate or
accelerate the dissolution of an absorbable implant, and/or to
release or accelerate the setting time of an adhesive or protein
solder, for example.
[0717] Stent-jackets for noninvasive heating incorporate as many
gas exchange perforations as necessary, resistance posed to the
eddy currents compensated for by increasing the intensity of
induction. Implants encompass both those circumductal, such as
stent-jackets, impasse-jackets, and clasp-magnets, as well as those
ductus-intramural, consisting of miniballs and stays. Shallow
implants are usually warmed (or chilled) directly with the aid of a
vortex tube-based, nominally `cold,` air gun, which is equally
usable for heating, or an electrical hand dryer, for example, while
remote heating of more deeply placed implants is usually by means
of induction in a ferromagnetic particulate embedded within the
material of the implant by placing the patient in a radiofrequency
alternating magnetic field, the means for accomplishing this
magnetically addressed below in the section entitled Heating of
Implants and Coated Implants, to Include Miniballs, Stays, and
Prongs Using Implant-passive Ductus-external or Extrinsic
Means.
[0718] This property in a temporary or absorbable implant can be
used to direct dissolution of the implant on demand. While most
often pertinent to stent-jackets, remote warming and dissolution
apply to every type implant described herein. The eventual object
of oral administration will allow self medication by the patient
away from the clinic, without the need for infusion or injection
through a subcutaneously implanted portal, as addressed above in
the section above entitled System Implant Magnetic Drug and
Radiation Targeting and in the section below entitled Cooperative
use of impasse-jackets in pairs and gradient arrays. When the
implant collars about the ductus, drug carrier nanoparticles, for
example, injected upstream will be drawn up against the lumen wall
within the collared segment.
[0719] Absorbable implants that are made to radiate heat on demand
can also be dissipated on demand, with drugs or other therapeutic
substances incorporated into the absorbed matrix released as well.
To do this, heating is not to the tissue injuring melting point but
to only the temperature needed to release bound water with or
without dissolution enzymes from a hydrogel likewise embedded in
the matrix. Implants remotely energized to radiate heat in situ are
addressed below in the section entitled Extracorporeal Energization
of Intrinsic Means for Radiating Heat from within Medication
Implants and Medication and/or the Tissue Bonding-coatings of
Implants.
[0720] The same nanoparticles that allow heating in an alternating
magnetic field produced with a magnetic resonance machine or high
amplitude alternating magnetic field generator make possible
magnetic drug-targeting in a nonalternating magnetic field. With an
extraluminal stent encircling the ductus (usually a blood vessel)
without, rather than an endoluminal stent, which inside the lumen
draws drug carrier nanoparticles, for example, to itself rather
than into the tissue adluminal to it, the drug is drawn into the
diseased tissue. The distinction between heating implants by
radiation or conduction from an extrinsic heat source and including
means within the implants that allow intrinsic heat generation is
addressed below in the section entitled Extracorporeal Energization
of Intrinsic Means for Radiating Heat from within Medication
Implants and Medication and/or the Tissue Bonding Coatings of
Implants.
[0721] Thus, miniballs and drug carrier nanoparticles are first
drawn to the stent-jacket, holding jacket, or magnet-jacket
collaring about a blood vessel, for example, whereupon heating the
jacket and apposed drug delivery agent or agents implants
accelerates the dissolution and uptake of the medication by the
lesion. When the core of a miniball with multiple layers of
medication or other therapeutic substance such as a surgical
cement, for example, is made to radiate heat, the layer having the
lowest breakdown or melting point will liquify or melt first,
allowing drugs or other therapeutic substances with different
breakdown points to be sequenced for delivery. Applying the
medication or other therapeutic substance with the lowest melting
point as the outermost layer results in the release of that
substance first. By shutting off and restarting the alternating
magnetic field, each successive layer can be heat-released at any
interval desired. Alternatively, each layer can be formulated to
dissolve at successive intervals postoperatively.
[0722] The use of a magnetic resonance machine or a high amplitude
alternating magnetic field applicator to heat the implants
described herein is also addressed below in the section entitled
Extracorporeal Energization of Intrinsic Means for Radiating Heat
from within Medication Implants and Medication and/or the Tissue
bonding-Coatings of Implants. Made of or coated to include
materials that can be excited when placed in an extracorporeal
magnetic field alternated at a radiofrequency, the implants
described herein, to include miniballs, stays, and holding jackets,
for example, can be made to radiate heat through oscillation and
eddy current induction. In such use, the impasse-jacket is given an
absorbable polymeric coating that incorporates the nanoparticles.
When this matrix can be raised in temperature to a sufficiently
molten or fluid state, physical alternation of the nanoparticles
also contributes to heating.
[0723] Remote heating by such means has been widely studied (see,
for example, Purushotham, S., Chang, P. E., Rumpel, H., Kee, I. H.,
Ng, R. T., Chow, P. K., Tan, C. K., and Ramanujan, R. V. 2009.
"Thermoresponsive Core-shell Magnetic Nanoparticles for Combined
Modalities of Cancer Therapy," Nanotechnology 20(30):305101. Luo,
Y. L., Fan, L. H., Gao, G. L., Chen, Y. S., and Shao, X. H. 2009.
"Fe3O4/PANI/P(MAA-co-NVP) Multilayer Composite Microspheres with
Electric and Magnetic Features: Assembly and Characterization,"
Journal of Nanoscience and Nanotechnology 9(11):6439-6452; Dennis,
C. L., Jackson, A. J., Borchers, J. A., Hoopes, P. J., Strawbridge,
R. and 4 others 2009. "Nearly Complete Regression of Tumors via
Collective Behavior of Magnetic Nanoparticles in Hyperthermia,"
Nanotechnology 20(39):395103; Li, F. R., Yan, W. H., Guo, Y. H.,
Qi, H., and Zhou, H. X. 2009. "Preparation of
Carboplatin-Fe@C-loaded Chitosan Nanoparticles and Study on
Hyperthermia Combined with Pharmacotherapy for Liver Cancer,"
International Journal of Hyperthermia 25(5):383-391; Maier-Hauff,
K., Rothe, R., Scholz, R., Gneveckow, U., Wust, P., and 6 others
2007. "Intracranial Thermotherapy Using Magnetic Nanoparticles
Combined with External Beam Radiotherapy: Results of a Feasibility
Study on Patients with Glioblastoma Multiforme," Journal of
Neuro-oncology 81(1):53-60; Baker, I., Zeng, Q., Weidong, L., and
Sullivan, C. R. 2006. "Heat Deposition in Iron Oxide and Iron
Nanoparticles for Localized Hyperthermia," Journal of Applied
Physics 99(8) 08H106-08H109; Zhao, D. L., Zhang, H. L., Zeng, X.
W., Xia, Q. S., and Tang, J. T. 2006. "Inductive Heat Property of
Fe3O4/Polymer Composite Nanoparticles in an AC Magnetic Field for
Localized Hyperthermia," Biomedical Materials 1(4):198-201;
Kawashita, M., Tanaka, M., Kokubo, T., Inoue, Y., Yao, T., Hamada,
S., and Shinjo, T. 2005. "Preparation of Ferrimagnetic Magnetite
Microspheres for in Situ Hyperthermic Treatment of Cancer,"
Biomaterials 26(15):2231-2238; Ramachandran, N. and Mazuruk, K.
2004. "Magnetic Microspheres and Tissue Model Studies for
Therapeutic Applications," Annals of the New York Academy of
Sciences 1027:99-109; R., DeNardo, S. J., Daum, W., Foreman, A. R.,
Goldstein, R. C., Nemkov, V. S., and DeNardo, G. L. 2005.
"Application of High Amplitude Alternating Magnetic Fields for Heat
Induction of Nanoparticles Localized in Cancer," Clinical Cancer
Research 11(19 Part 2):7093s-7103s; Muraoka, A., Takeda, S.,
Matsui, M., Shimizu, T., Tohnai, I., Akiyama, S., and Nakao, A.
2004. "Experimental Study of a Novel Thermotherapy for
Hepatocellular Carcinoma Using a Magnesium Ferrite Complex Powder
that Produces Heat under a Magnetic Field," Hepatogastroenterology
51(60):1662-1666; Kobayashi, T., Tanaka, T., Kida, Y., Matsui, M.,
and Ikeda, T. 1989. "Interstitial Hyperthermia of Experimental
Brain Tumor Using Implant Heating System," Journal of
Neuro-oncology 7(2):201-208).
[0724] Ordinarily, ferromagnetic implants disallow the use of
magnetic resonance equipment. This is because the axial field
places tractive force on the implants risking injury, while the
radiofrequency alternating field induces heat that results in
burns. However, use of an alternating magnetic field only can also
serve as a means for intentionally heating an implant directly or
by exciting a resonant circuit embedded within the implant (Niwa,
T., Takemura, Y., Inoue, T., Aida, N., Kurihara, H., and Hisa, T.
2008. "Implant Hyperthermia Resonant Circuit Produces Heat in
Response to MRI Unit Radiofrequency Pulses," British Journal of
Radiology 81(961):69-72, available at
http://bjr.birjournals.org/cgi/content/ful1/81/961/69; Morita, M.,
Inoue, T., Yamada, T., Takemura, Y., and Niwa, T. 2005. "Resonant
Circuits for Hyperthermia Excited by RF Magnetic Field of MRI,"
INTERMAG Asia Magnetics Conference 953-954). Digests of the IEEE
International).
[0725] The resonant circuit is interposed or sandwiched between a
double layered mesh in the half-cylinder to be placed more deeply
or on the side that will lie more distant from the external
extraction electromagnet, for example. Unlike stent-jackets, which
use multiple miniballs implanted relatively close to the outer
tunic of the ductus where each is drawn by a magnetic force which
is close and normal to it, a holding jacket will often secure but a
single miniball within the lumen through which contents flow over
the additional distance that separates the perimedial from an
endoluminal position when the magnetized segment of the jacket is
central and less extended.
[0726] For use in the gastrointestinal tract, ureters, and
gamete-tranporting ductus, the magnetic strength must be
additionally strong enough to overcome the adaxial (toward the long
axis, medial, central, inward) increase in distance due to
retraction by the passing contractive waves. In the esophagus and
gut, the immediately preceding passage of the bolus poses yet an
additional force promoting dislodgement. However, the
impasse-jacket strength of magnetization must not be so great as to
interfere with ductus-intrinsic muscular action to a degree that
would induce dyspagia, for example. Whether a radially symmetrical
arrangement of miniballs suspended within the lumen would less
likely produce disabling consequences warrants study.
[0727] 4d. Chemical Adjuvants and Precautionary Measures
[0728] 4d(1). Administration of Target and Target-Adjacent
Implantation-Preparatory Substances
[0729] Radial projection unit injection tool-inserts allow the
local injection of therapeutic substances such as drugs, hormones,
enzymes, or a surgical cement into the target and nearby tissue to
prepare the ductus for ballistic implantation. Avoidance of the
lumen a key object in the use of stays, the extraluminal
application of medication is preferred with stays. Therapeutic
substances can also be administered systemically or released onto
the endothelium through a noninjecting ejection tool-inserts or
through a barrel-tube or tubes used as service channels. In
addition to conventional types of medication such as antibiotics
and antithrombogenics, to better resist migration, delamination, or
pull-through, tissue hardening agents that induce the formation of
strong tissue about the implants and strong adhesion of the tissue
to the implants is used.
[0730] Due to the thrombogenicity (thromboplasticity) of
introducing multiple punctures through the intima and media,
miniballs for implantation into the walls of arteries are given an
outer coating of an antiplatelet agent, such as a glycoprotein
IIB/IIA inhibitor (abciximab, eptifibatide, tirofiban, lamifiban),
or adenosine uptake inhibitor (dipyridamole), and those for veins
with an anticoagulant or `blood thinner,` such as the vitamin K
antagonists or coumarins (warfarin and/or heparin) and non vitamin
K antagonists (see, for example, De Caterina, R., Husted, S.,
Wallentin, L., Andreotti, F., Arnesen, H., and 11 others 2012. "New
Oral Anticoagulants in Atrial Fibrillation and Acute Coronary
Syndromes: ESC [European Society of Cardiology] Working Group on
Thrombosis-Task Force on Anticoagulants in Heart Disease Position
Paper," Journal of the American College of Cardiology 2012
59(16):1413-1425; Weitz, J. I. 2012. "New Oral Anticoagulants: A
View from the Laboratory," American Journal of Hematology 87
Supplement 1:S133-S136; Bauer, K. A. 2011. "Recent Progress in
Anticoagulant Therapy: Oral Direct Inhibitors of Thrombin and
Factor Xa," Journal of Thrombosis and Haemostasis 9 Supplement
1:12-9; Weitz, J. I., Hirsh, J., and Samama, M. M. 2004. "New
Anticoagulant Drugs," Chest 126(3):Supplement 265S-286S), thus
allowing the systemic dose to be reduced relative to that
conventional, and reducing the risk for prolematic bleeding. On
healing an extraluminal, with no presence within the lumen, ceases
to pose a threat of thrombosis.
[0731] Ductus prone to swell if struck from within necessitate the
use of miniballs that also contain anti-inflammatory medication,
the NSAIDs diclofenac, indometacin, ibuprofen and sulindac, for
example, having been found to additionally exert an
antiproliferative effect on the smooth muscle cells of the media
(Munoz, E., Valero, R. A., Quintana, A., Hoth, M., N nez, L., and
Villalobos, C. 2011. "Nonsteroidal Anti-inflammatory Drugs Inhibit
Vascular Smooth Muscle Cell Proliferation by Enabling the
Ca2+-dependent Inactivation of Calcium Release-activated
Calcium/Orai Channels Normally Prevented by Mitochondria," Journal
of Biological Chemistry 286(18):16186-16196; Brooks, G., Yu, X. M.,
Wang, Y., Crabbe, M. J., Shattock, M. J., and Harper, J. V. 2003.
"Non-steroidal Anti-inflammatory Drugs (NSAIDs) Inhibit Vascular
Smooth Muscle Cell Proliferation via Differential Effects on the
Cell Cycle," Journal of Pharmacy and Pharmacology 55(4):519-526).
To reduce the risk of infection-mediated pull-through, the implants
are additionally coated with an antibiotic, a dose adjusted
systemic antibiotic administered as well.
[0732] Other measures for reducing the risk of pull-through include
use of the minimal retractive magnetic field strength, implants
having a textured surface to encourage tissue adhesion and
infiltration, or ingrowth, the application of phosphorylcholine
and/or dexamethasone or curcumin (referencees provided below in the
section entitled Tissue Reaction Ameliorative Measures), and
various bonding agents, such as protein solder or tissue cement,
dependent upon the response to be expected for the type and depth
of tissue based upon the results of pretesting as addressed below
in the section entitled Testing and Tests. Due to the constant
replenishment of tissue, adhesives are chosen that will allow
infiltration during dissolution so that the implant will become
securely anchored and integrated in position.
[0733] In the form of smaller miniballs or stays, these substances
are solid and can consist of a single or multiple drugs. The
heating of solder coated implants following insertion can be used
both to release drugs and bind tissue. To minimize the exposure of
surrounding tissue to this heat, electrically or fluidically heated
heat-windows, as addressed below in the section entitled Thermal
Conduction Windows (Heat-windows) and Insulation of the Muzzle-head
Body, or syringe solder injectors, as addressed below under the
heading Radial Projection Units are used. Alternatively, external
ultrasound can be used for heating. Other preparatory agents allow
the intentional swelling of the ductus wall, as next addressed, to
make thin-walled ductus easier if not possible to implant.
[0734] The moisture barrier protected viscoelastic polyurethane
(memory) foam lining of the stent-, impasse, and magnet-jackets
described facilitate the inclusion of adherent tissue surrounding
the outer ductus when thin-walled due to normal anatomy or disease.
The treatment of short segments will often recommend the use of
stays, as addressed below in the section entitled Circumstances
Dissuading or Recommending the Use of Stays. When the same means
for inserting ferromagnetic implants to draw a magnetic
stent-jacket can be used to introduce the preparatory medication,
the treatment site can often be targeted with negligible systemic
dispersion. When the drug action response time allows, use of the
same barrel-assembly allows single entry and withdrawal.
[0735] When a pretest reveals that the wall of the ductus is
susceptible to inter or intralaminal separation, small implants
consisting of an absorbable and tissue infiltatable solid protein
solder can be implanted adjacent to the site to be implanted with
the solder melted (denatured) and made to flow by muzzle-head or
piped radial projection unit heat-windows, by feeding heated gas
down a barrel-tube, or through use of external ultrasound.
Following any step involving heating, a cooling catheter, as
addressed below in the section entitled Cooling Catheters
(Temperature-changing Service-catheters), can be used to hasten the
return of heated tissue to body temperature. When the cooling
catheter is prepared by having been stored filled with water in a
freezer and the same barrel-tube is to be used for discharge, the
cooling catheter should be capped to prevent melt water from
entering the barrel-tube.
[0736] Deeply textured implants can deliver surface depression
adherent liquid or semiliquid substances forward into the ductus
wall. Using a barrel-assembly, a service-catheter, as addressed
below in the section of like title, and using a stay insertion
tool, auxiliary syringes, as addressed below in the section
entitled Stay Insertion Tool Auxiliary Syringes, make it possible
to supplement or coat implants. Outside the bloodstream, a
service-catheter also allows the delivery of a gas or an aerosol
(mist) whether irradiated or having a fine powder dispersed in it.
With the latter, cohesiveness among particles or adhesion to the
barrel-tube as service channel without a service-catheter will
result in clogging, limiting continued use of any one
barrel-tube.
[0737] Barrel-tubes as service channels and service-catheters can
deliver compatible substances jointly, but unless more than one
service-channel--as addressed below in the sections entitled
Muzzle-head Access through a Service-channel without the Aid of and
by Means of Inserting a Service-catheter and Thermal Ablation or
angioplasty- (Lumen Wall Priming Searing- or Cautery-) capable
Barrel-assemblies--is available, to deliver substances to be kept
separated during delivery requires separation through the use of
separate service-channels or service-catheters in sequence.
[0738] 4d(2). Ductus Wall Tumefacients
[0739] Whether the result of disease, an angioplasty, or an
atherectomy, excessive thinness of the luminal wall can prohibit
implantation to introduce medication or to apply a magnetic stent.
Otherwise, numerous vessels, especially veins and elastic arteries
having a thin wall and media, even a carotid, may prove difficult
or impossible to implant thus. In some instances, implantation is
made possible by producing a short-lived or reversible increase in
medial thickness. Provided the tenuity is not so extreme or
intrinsic strength so lacking that upon subsidence, the implants,
even with a fill-coat of protein solder, would perforate through
the adventitia, into the lumen, or both, some walls can be brought
up to an implantable thickness if tumefied (swollen).
[0740] Long-term fillers as opposed to short term swellants are
addressed below in the section entitled The Extraductal Component
of the Extraluminal Stent and the Means for its Insertion.
Administration of a tumefacient specified in this section and drugs
specified in the section that follows is begun sufficiently in
advance of the procedure that requires it. In muscular arteries,
tumefacients, or swelling agents, which increase lumen wall
thickness by contracting the smooth muscle cells, are
vasoconstictors that will reduce the diameter of the lumen. This
can be a consideration in selecting a barrel-assembly or radial
projection catheter of given caliber but will rarely if ever affect
the use of stays. Tumefacients not only increase the thickness of
the luminal wall allowing it to be implanted but affect other
properties of the ductus.
[0741] Tumefacients that work by inducing the contraction of medial
smooth muscle, for example, increase resistance of the wall to
perforation and reduce the luminal diameter. Tumefacients that work
in other ways may not affect luminal diameter but will affect the
mechanical properties of the luminal wall. In some instances, the
primary object in using a tumefacient may be unrelated to wall
thickness. This interaction of key determinants as to the
barrel-assembly and exit velocity to be used means that the tests
described below in the section entitled Testing and Tests should be
performed both before and after any tumefacient contemplated is
applied. Tumefacients that affect the ductus over a longer interval
that wanted must have an associated counteractant. This can be done
to thicken a wall that is or is not too thin to implant but not too
weak to retain an implant once inserted.
[0742] Tumefaction does not involve the permanent implantation of
autologous tissue or a polymer between the intima and adventitia
but swelling that is temporary to allow or expedite insertion.
Otherwise, liposuctioned fat, for example, can be injected through
a service-catheter (qv.) with a hypotube, or with an injection
tool-insert (qv.) before implantation. Depending upon lumen
caliber, the tumefacient can be released along the lumen wall
through the working channel of a fiberoptic endoscope, a
barrel-tube used as a service-channel, a service catheter routed
through a barrel-tube, or an ejection tool-insert. If not extremely
thin-walled, the use of an injection tool-insert or
service-catheter with a hypotube at the distal end is possible.
[0743] Following the procedure, the wall reverts to its
preprocedural condition, the implant or implants retained for a
time if necessary with the aid of a surgical cement or protein
solder outer layer pending tissue integration. Low melting point
solder on miniballs or stays and cyanoacrylate cement on stays can
be heated endoluminally by muzzle-head heat-windows or hot-plate
tool-inserts. Heating thus is focused or aimed and relatively
circumscribed. Heating from outside the body using ultrasound, for
example, is unfocused and contraindicated for any site close to a
developmental ossification or nervous center, for example. When
stays are to be used or the ductus is to be stented so that
extraluminal access will be required in any event, the tumefacient
can be applied to or through the adventitia.
[0744] Various approaches to thickening the media include inducing:
a. A buildup of osmotic pressure that causes the smooth muscle of
the media to contract (see, for example, Ding, Y., Schwartz, D.,
Posner, P., and Zhong, J. 2004. "Hypotonic Swelling Stimulates
L-type Ca2+ Channel Activity in Vascular Smooth Muscle Cells
Through PKC [Protein Kinase]," American Journal of Physiology. Cell
Physiology 2004 287(2):C413-C421); b. A short-lived or reversible
swelling reaction to a drug or combination of drugs; c. Sterile
inflammation as an immune response; d. Reaction to a change in
temperature, e. Reaction to a flow of current at the target site,
f. Mechanical irritation through brief oscillation of the target
site, and injection of a nonirritating absorbable filler such as
used in facial cosmetic surgery.
[0745] In an atheromatous artery to receive miniballs, embolic
protective devices such as proximal and distal balloon occluders
and embolic filters (see, for example, section 4d(2) entitled
Ductus Wall Tumefacients and Kobayashi, T. anf Giri, J. 2017. "The
Role of Embolic Protection in Carotid Stenting Progress in
Cardiovascular Diseases (PCVD)," Progress in Cardiovascular
Diseases 59(6):612-618; Velasco, A. and Mosimann, P. J. 2013.
"Distal Cerebral Protection Device Filled with Calcified Plaque
Debris after Carotid Stenting," Journal of the American College of
Cardiology. Cardiovascular Interventions 6(4):e22-e23; Macdonald,
S. 2011. "New Embolic Protection Devices: A Review," Journal of
Cardiovascular Surgery (Turin, Italy) 52(6):821-827; Eskandari, M.
K. 2005. "Cerebral Embolic Protection," Seminars in Vascular
Surgery 18(2):95-100; Sangiorgi, G. and Colombo, A. 2003. "Embolic
Protection Devices," Heart (London, England) 89(9):990-992) that
is, a potentially embolizing atheromatous debris-intercepting
trap-filter or balloon deployed from the nose of the muzzle-head
can be prepositioned proximal or distal to or downstream from the
site to be treated.
[0746] No embolization device completely eliminates the passage of
microemboli; however, the number which pass is much reduced (Vos,
J. A. 2017. "Evidence Overview: Benefit of Cerebral Protection
Devices During Carotid Artery Stenting," Journal of Cardiovascular
Surgery (Turin, Italy) 58(2):170-177; Kassavin, D. S. and Clair, D.
G. 2017. "An Update on the Role of Proximal Occlusion Devices in
Carotid Artery Stenting," Journal of Vascular Surgery
65(1):271-275; Knur, R. 2014. "Technique and Clinical Evidence of
Neuroprotection in Carotid Artery Stenting," VASA. Zeitschrift fur
Gefasskrankheiten [Journal for Vascular Diseases] 43(2):100-112;
Atkins, M. D. and Bush, R. L. 2007. "Embolic Protection Xevices for
Carotid Artery Stenting: Have They Made a Significant Difference in
Outcomes?," Seminars in Vascular Surgery 20(4):244-251). Walls too
thin to implant must first be made thicker. Since injection of the
ductus wall with a tumefacient or fill-tissue will affect its
mechanical properties, the applicable pretest or pretests are
performed at the site following injection to thicken, for example.
Testing is addressed below in the section entitled Testing and
Tests. The results of testing will determine the need for a target
tissue binder or hardener, implants with a layer of protein solder
or tissue cement, for example, then used.
[0747] 4d(3). Nontumefacient Enabled Attainment of Implantable
Ductus-Intramural Thickness
[0748] Infrequently, a disease condition, such as inflammation as
swelling, a lesion, or inflammation that follows treatment of the
lesion will result in a wall thickness sufficient for implantation,
although this will usually be at the expense of strength. A
malacotic condition can be overcome by using a radial projection
catheter to inject an absorbable tissue hardener or fixative, or
filler of the kind used in facial cosmetic surgery. An
intravascular ultrasound probe, charge coupled device camera, or
fluorescence lifetime imaging microscopy, or angioscope--either as
a separate device or incorporated into a combination form
barrel-assembly--can be used to examine the reaction of the lumen
wall to the procedure just completed (see, for example, Savastano,
L. E. and Seibel, E. J. 2017. "Scanning Fiber Angioscopy: A
Multimodal Intravascular Imaging Platform for Carotid
Atherosclerosis," Neurosurgery 64(CN Supplement 1):188-198;
Savastano, L. E., Chaudhary, N., Murga-Zamalloa, C., Wang, M.,
Wang, T., and Thompson, B. G. 2017. "Diagnostic and Interventional
Optical Angioscopy in Ex Vivo Carotid Arteries," Operative
Neurosurgery (Hagerstown, Md.) 13(1):36-46; Savastano, L. E., Zhou,
Q., Smith, A., Vega, K., Murga-Zamalloa, C., and 11 others 2017.
"Multimodal Laser-based Angioscopy for Structural, Chemical and
Biological Imaging of Atherosclerosis," Nature Biomedical
Engineering 1. pii: 0023; Savastano, L. E., Smith, A., Vega, K.,
Murga-Zamalloa, C., Gordon, D., and 4 others 2016. "Multimodal
Endovascular Endoscopy in Carotid Atherosclerotic Disease,"
Neurosurgery 63 Supplement 1:146; Packard, R. R., Zhang, X., Luo,
Y., Ma, T., Jen, N., and 7 others 2016. "Two-point Stretchable
Electrode Array for Endoluminal Electrochemical Impedance
Spectroscopy Measurements of Lipid-laden Atherosclerotic Plaques,"
Annals of Biomedical Engineering 44(9):2695-2706; Ma, T., Yu, M.,
Li, J., Munding, C. E., Chen, Z., Fei, C., Shung, K. K., and Zhou,
Q. 2015. "Multi-frequency Intravascular Ultrasound (IVUS) Imaging,"
Institute of Electrical and Electronics Engineers Transactions on
Ultrasonics, Ferroelectrics, and Freqency Control 62(1):97-107;
McVeigh, P. Z., Sacho, R., Weersink, R. A., Pereira, V. M.,
Kucharczyk, W., Seibel, E. J., Wilson, B. C., and Krings, T. 2014.
"High-resolution Angioscopic Imaging During Endovascular
Neurosurgery," Neurosurgery 75(2):171-180; Suter, M. J., Nadkarni,
S. K., Weisz, G., Tanaka, A., Jaffer, F. A., Bouma, B. E., and
Tearney, G. J. 2011. "Intravascular Optical Imaging Technology for
Investigating the Coronary Artery," Journal of the American College
of Cardiology. Cardiovascular Imaging 4(9):1022-1039; Chou, T. M.,
Fitzgerald, P. J., and Yock, P. G. 2000. "Intravascular
Ultrasound," Chapter 19 in Baim, D. S. and Grossman, W., Grossman's
Cardiac Caherterization, Angiography, and Intervention,
Philadelphia, Pa.: Lippincott Williams and Wilkins). With a
combination-form radial projection catheter, a small intravascular
ultrasound probe passed down the bore pre or midprocedurally can be
used to observe the effect on wall thickness of the atherectomy
just completed using the projection catheter, an angioscope useful
to examine the lumen interior.
[0749] The administration of a nominally nontumefacient drug
specified in this section is begun sufficiently in advance to
obtain the desired effect by the time of the procedure. If
additional thickness is necessary, projection catheter radial
projection unit injection tool-inserts, for example, can be used to
deliver a tumefacient and the intravascular ultrasound or
angioscope used to confirm the result. The ultrasound cable is then
withdrawn and the barrel-assembly passed down through the bore to
initiate miniball discharge. In this process, the radial projection
catheter is not withdrawn but remains as both atherectomy device
and guide catheter. If the pretest prescribed below in the section
entitled Testing and Tests indicates a lack of strength that will
subside on healing, consideration may be given to using a
quick-acting tissue binder-hardener rather than aborting
implantation.
[0750] The use of a bipartite combination-form angioplasty-capable
barrel-assembly represents a reciprocal arrangement, whereby the
barrel-assembly is used to perform the atherectomy or other
treament with a viewing probe in its bore. However, in this case,
the probe need not be withdrawn; if additional radial projection
units are need, a matching combination-form radial projection
catheter is slid over the barrel-catheter as guide wire.
Vasodilators relax the walls of vessels, which temporarily reduces
the intimal-medial thickness, while vasoconstictors (vasopressors)
effectively toughen the media, due both to increased medial
thickness and vasotension.
[0751] Here the application of medication is targeted, the
tumefacient, as can any other fluid or semifluid therapeutic
substance, injected into the site along the lumen wall to be
treated by an injection syringe tool-insert, as addressed below in
the section entitled Radial Projection Unit Tool-Inserts, so that
the hypertensive effect is substantially confined to the treatment
site, making the use of potent hypertensives applicable to patients
in whom the systemic use of the same drugs would be ill-advised and
avoiding vasoconstriction that reducing the luminal diameter, would
hinder intervention. Where apposite, preparatory systemic
medication may be prescribed to increase vascular tonus and wall
thickness.
[0752] Over time, some vasoconstrictors, such as urotensin II,
directly stimulate cell proliferation rather than produce this
result only indirectly as a consequence of having increased the
blood pressure (see, for example, Zhang, Y. G., Li, J., Li, Y. G.,
and Wei, R. H. 2008. "Urotensin II Induces Phenotypic
Differentiation, Migration, and Collagen Synthesis of Adventitial
Fibroblasts from Rat Aorta," Journal of Hypertension
26(6):1119-1126; Tamura, K., Okazaki, M., Tamura, M., Isozumi, K.,
Tasaki, H., and Nakashima, Y. 2003. "Urotensin II-induced
Activation of Extracellular Signal-regulated Kinase in Cultured
Vascular Smooth Muscle Cells: Involvement of Cell Adhesion-mediated
Integrin Signaling," Life Sciences 72(9): 1049-1060).
[0753] Where its systemic use is not contraindicated, urotensin II
may effectively contribute needed strength in the airway, for
example, (see, for example, Chen, Y. H., Zhao, M. W., Yao, W. Z.,
Pang, Y. Z., and Tang, C. S. 2004. "The Signal Transduction Pathway
in the Proliferation of Airway Smooth Muscle Cells Induced by
Urotensin II," [in English] Chinese Medical Journal 117(1):37-41).
Systemic hypertensives are not used where hypertension and stenosis
are primary complaints; however the one-time and highly localized
use of a quick-acting tonus-increasing drug poses little risk. The
object is to thicken and effectively strengthen the arterial wall
so that it can be implanted and not to strengthen the wall
postprocedurally. The short-term and localized hypertension
subsides following the procedure and does not represent the
postprocedural strength of the vessel wall, which is measured using
procedures described below in the section entitled Testing and
Tests.
[0754] Testing is performed in preparation for implantation
following angioplasty or atherectomy, if applicable, and before and
after administering the drug. The postprocedural administration of
a systemic vasoconstrictor is unacceptable with most vascular
disease. An alternative approach for sustaining strength long
enough to allow tissue recovery without delamination or
pull-through is to surround the implant with a surgical cement or
protein solder that bonds the implant to and hardens the
surrounding tissue. Any stiffening in the ductus wall is tightly
focused with little effect on the intrinsic motility of the smooth
muscle.
[0755] Drugs distinct in pharmacological action, response time, and
persistence with the individual or combined potential to cause the
ductus wall to increase in thickness more quickly when applied
topically (through a service-catheter or auxiliary syringe to be
described) include zymosan; carrageenan, dextran, uric acid,
adrenalin, tumor necrosis factor-alpha, sterile lipopolysaccharide
and lipo-oligo-saccharide endotoxins (see, for example, Kitazawa,
M., Oddo, S., Yamasaki, T. R., Green, K. N., and LaFerla, F. M.
2005. "Lipopolysaccharide-induced Inflammation Exacerbates Tau
Pathology by a Cyclin-dependent Kinase 5-mediated Pathway in a
Transgenic Model of Alzheimer's Disease," Journal of Neuroscience
25(39):8843-8853). If necessary, once the thickness will admit
implants, the implants can carry a coating of these.
[0756] Endotoxins should be kept away from the bloodstream.
Antidotes are discussed in the literature (see, for example, Jiang,
Z., Hong, Z., Guo, W., Xiaoyun, G., Gengfa, L., Yongning, L., and
Guangxia, X. 2004. "A Synthetic Peptide Derived from
Bactericidal/Permeability-increasing Protein Neutralizes Endotoxin
in Vitro and in Vivo," International Immunopharmacology
4(4):527-537; Bhor, V. M., Thomas, C. J., Surolia, N., and Surolia,
A. 2005. "Polymyxin B: An Ode to an Old Antidote for Endotoxic
Shock," Molecular BioSystems 1(3):213-222; Ren, J. D., Gu, J. S.,
Gao, H. F., Xia, P. Y., and Xiao, G. X. 2008. "A Synthetic Cyclic
Peptide Derived from Limulus Anti-lipopolysaccharide Factor
Neutralizes Endotoxin in Vitro and in Vivo," International
Immunopharmacology 8(6):775-781).
[0757] Other drugs with the potential to cause an increase in
intimal-medial thickness as ligands that bind to Toll-like
receptors and thus activate immune cell responses include
midazoquinoline, loxoribine, bropirimine, sterile profilin, sterile
flagellin (see, for example, Neish, A. S. 2006. "TLRS [Toll-like
Receptors] in the Gut. II. Flagellin-induced Inflammation and
Antiapoptosis," American Journal of Physiology. Gastrointestinal
and Liver Physiology 292(2):G462-G466), and polyglycolic acid (see,
for example, Ceonzo, K., Gaynor, A., Shaffer, L., Kojima, K.,
Vacanti, C. A., and Stahl, G. L. 2006. "Polyglycolic Acid-induced
Inflammation: Role of Hydrolysis and Resulting Complement
Activation," Tissue Engineering 12(2):301-308).
[0758] Yet other drugs with the potential to cause an increase in
intimal-medial thickness are oxysterols (oxidized cholesterol)
(see, for example, Lemaire-Ewing, S., Prunet, C., Montange, T.,
Vejux, A., and six other authors 2005. "Comparison of the
Cytotoxic, Pro-oxidant and Pro-inflammatory Characteristics of
Different Oxysterols," Cell Biology and Toxicology 2005
21(2):97-114; Joffre, C., Leclere, L., Buteau, B., Martine, L., and
seven other authors 2007. "Oxysterols Induced Inflammation and
Oxidation in Primary Porcine Retinal Pigment Epithelial Cells,"
Current Eye Research 32(3):271-280), thromboxane B.sub.2,
aldosterone (see, for example, Sun, Y., Zhang, J., Lu, L., Chen, S.
S., Quinn, M. T., and Weber, K. T. 2002. "Aldosterone-induced
Inflammation in the Rat Heart: Role of Oxidative Stress," American
Journal of Pathology 161(5):1773-1781), and prostaglandin E.sub.2
(see, for example, Lees, P., McKellar, Q. A., Foot, R., and
Gettinby, G. 1998. "Pharmacodynamics and Pharmacokinetics of
Tolfenamic Acid in Ruminating Calves: Evaluation in Models of Acute
Inflammation," Veterinary Journal 155(3):275-288; Sidhu, P. K.,
Landoni, M. F., and Lees, P. 2006. "Pharmacokinetic and
Pharmacodynamic Interactions of Tolfenamic Acid and Marbofloxacin
in Goats," Research in Veterinary Science 80(1):79-90).
[0759] Both miniballs and stays can consist of a single drug or
aggregations or concentric layers of drugs and can be implanted
adjacent or proximal to the site for implantation making it
possible to deliver a concentrated dose to a targeted location.
Still other drugs with the potential to cause an increase in
intimal-medial thickness are fibrinogen, sterile lipoproteins,
glycolipids, lipteichoic acid, heparan sulphate fragments,
hyaluronic acid fragments, and imiquimod.
[0760] 4e. Stabilization of the Implant Insertion Site
[0761] 4e(1). Gross Positional Stabilization (Immobilizaton) of the
Implant Insertion Site
[0762] Peristalsis and the pulse change the radial distance between
the target and the longitudinal axis of the lumen, changing the
miniball aiming point or the stay insertion site. This must be
considered for both arteries and contactile ducti from within the
lumen for miniballs and from outside the ductus for stays.
Generally, the pulse is frequent but can seldom result in
misplacements of any significance, even when implantation is under
unpaced automatic positional and discharge control. A reduction in
motility can be brought about by numerous drugs, mechanical
interventions, and changes in temperature, which latter can be used
to reduce motility at the gross, histologic, and metabolic
levels.
[0763] The use of temperature is addressed below in the section
entitled Temperature Stabilization. Where the pulse interferes, a
primary method for slowing the heart is chilling; where local
anesthesia cannot be used in any event, this method should be
considered. Even when treating a coronary artery or vein graft,
on-pump operation should seldom prove necessary. Gastrointestinal
tract, ureteric, bile, and gamete conduit duct (vasa deferentia,
fallopian tubes) peristalsis, however, generate displacements that
can result in the longitudinal misplacement of miniballs and the
misplacement in depth of stays.
[0764] However, peristalsis, while different in form in different
type ductus (see, for example, Woodburne, R. T. and Lapides, J.
1972. "The Ureteral Lumen during Peristalsis," American Journal of
Anatomy 133(3):255-258), is intermittent and if necessary, readily
suppressed. With stays, peristalsis is less problematic, because it
is usually quelled as an inherent consequence of manipulating the
ductus. When access to the outside of the ductus has not been
created to insert a stent-jacket, medication is used. In the gut,
the contractive waves are slow enough to avoid, and if necessary,
temporary suppression or immobilization by neural blockade or a
drug such as glucagon or Valeant Pharmaceuticals International
Motofen.RTM. is accepted practice.
[0765] The coronary arteries not only pulsate but move with the
heart, except in the most practiced hands, precluding the off-pump
use of stays. On the systoles, the highly elastic pulmonary artery
expands 20-25 percent in diameter (see, for example, Lin, K. and
Can, J. C. 2015. "MR Imaging of the Coronary Vasculature: Imaging
the Lumen, Wall, and Beyond," Radiologic Clinics of North America
53(2):345-353; Ishida, M. and Sakuma, H. 2014. "Magnetic Resonance
of Coronary Arteries: Assessment of Luminal Narrowing and Blood
Flow in the Coronary Arteries," Journal of Thoracic Imaging
29(3):155-162; Lin, K., Lloyd-Jones, D. M., Liu, Y., Bi, X., Li,
D., and Carr, J. C. 2011. "Noninvasive Evaluation of Coronary
Distensibility in Older Adults: A Feasibility Study with MR
Angiography," Radiology 261(3):771-778; Weissman, N. J., Palacios,
I. F., and Weyman, A. E. 1995. "Dynamic Expansion of the Coronary
Arteries: Implications for Intravascular Ultrasound Measurements,"
American Heart Journal 130(1):46-51; Shelton, D. K. Jr. and Olson,
R. M. 1972. "A Nondestructive Technique to Measure Pulmonary Artery
Diameter and Its Pulsatile Variations," Journal of Applied
Physiology 33(4):542-544.). A muscular artery more amenable of
stenting as the treatment by the means described herein expands to
a lesser degree, and less still when sclerosed (see, for example,
Numao, T., Ogawa, K., Fujinuma, H., and Furuya, N. 1997. "Pulsatile
Diameter Change of Coronary Artery Lumen Estimated by Intraductal
Ultrasound." Journal of Cardiology (Amsterdam, Holland) 30(1):1-8
(in Japanese with abstract in English at Pubmed).
[0766] The difference in miniball impact force required to
perforate rather than to penetrate the luminal wall of most ductus
is sufficiently large that perforations should seldom occur. Except
in the gastrointestinal tract, where to prevent infection, a
perforation demands immediate intervention, such tiny perforations
self seal quickly. Because the targeted application of
anti-clotting medication allows the systemic dose to be minimized
if not eliminated, bleeding should not be a problem. If
stent-jacketed, over or under-shots beyond the intended margins can
be recovered or made functional by extending the stent-jacket. The
discharge control described herein is usually accomplished as an
auxiliary function of the automatic positioning system and not
synchronized to the phase of the pulse at the aiming point.
[0767] To provide an automatic ballistic triggering system to
actively adapt the timing of discharge to the instantaneous
position of the aiming point can be achieved by controlling both
the heart rate and discharge by pacing circuitry. This may become
necessary with a pulse too irregular for the operator to negotiate
manually. Disease may further complicate the variability in
frequency, amplitude, and tonicity of smooth muscle action. More
significantly, such a system is adaptable to the discharge of the
airgun, with which it is not essential, but not a stay insertion
tool, which is manually triggered based upon touch. Stabilization
of an insertion site may involve retarding the rate of
intracellular chemical activity as well as gross immobilization. If
needed, current cardiopulmonary bypass machines filter out the
microembolisms responsible for postperfusion syndrome.
[0768] If not to synchronize the action of the smooth muscle
itself, automatic means for effecting discharge would have to
synchronize to that action, which is achievable but should seldom
prove essential. In an artery, absolute radial displacement of the
wall by a pulse of reasonably normal amplitude will be too slight
to cause the target lesion to be missed, so that unsynchronized or
mistimed discharges are seldom likely to result in mispositioning
in such degree as to necessitate recovery of the implant. While a
hampering pulse is ordinarily dealt with using, automatic means for
controlling both the pulse and discharge of miniballs based upon
pacemaking circuitry avoids the need for sensing and synchronizing
discharge to the intrinsic motility as an adaptive function. The
use a bypass machine is avoided when possible but may be necessary
to avert hypoxia by luminal obstruction of the barrel-assembly as
well as to achieve stabilization.
[0769] Such circuitry can achieve a speed of discharge that
compensates for the loss in time had discharge to be limited to the
diastoles as with manual triggering. Thus, in most situations,
whether because the action is slow enough that the operator can
adapt, or, as is usual, the level (position along the ductus) of
placement is not so critical that the phase angle at the instant of
discharge must be taken into account, or because the intensity
and/or frequency can be suppressed with drugs or mechanical means,
the need for either an automatic sensing and triggering system for
adapting to peristalsis can be avoided whether stays or miniballs
are used. When miniballs must be positioned precisely, mistiming
the discharge in relation to the pulse phase will result in
mispositioning; however, the end positions of the miniballs will
not be affected by the infolding or pleating of the intima during
diastoles.
[0770] The difference in the mechanical properties of ductus in the
elderly, especially in the arterial tree (see, for example, Fonck,
E., Prod'hom, G., Roy, S., Augsburger, L., Rufenacht, D. A., and
Stergiopulos, N. 2007. "Effect of Elastin Degradation on Carotid
Wall Mechanics as Assessed by a Constituent-based Biomechanical
Model," American Journal of Physiology. Heart and Circulatory
Physiology 292(6):H2754-763; Samila, Z. J. and Carter, S. A. 1981.
"The Effect of Age on the Unfolding of Elastin Lamellae and
Collagen Fibers with Stretch in Human Carotid Arteries," Canadian
Journal of Physiology and Pharmacology 59(10):1050-1057) are
inherently adjusted for by the preliminary, in situ testing
prescribed below in the section entitled Testing and Tests.
[0771] The avoidance of instrumentation affords considerable
simplification. The stay insertion tool is weighted and made with a
base (working end, distal end) configured to effect subadventitial
insertion when passively resting upon the ductus and elevated by
the pulse. Even when the surrounding tissue encroaches upon or
clings to the tool alterring its effective weight (which can be
eliminated through use of a lubricant), the pulse, transmitted as
tactual feedback, is clearly superimposed upon the restraint,
adjustment accomplished if not spontaneously, then with the aid of
a tonometric or pressure sensing device. Extension or retraction of
the entry wound should not be necessary.
[0772] The pulse is felt over an interval sufficient to anticipate
successive peaks despite any extrasystoles, ectopic beats, or other
arrhythmial (arrhythmical) concomitant. Should a rapid or erratic
pulse not have responded to medication given in preparation for the
procedure and make it necessary, a hemostat (hemostatic clamp,
arterial forceps) introduced through a second laparoscopic incision
is used to clamp off the segment to be treated no longer than it
takes to insert one stay; the recovery of a mispositioned stay
posing no need to move the insertion tool or to suppress the pulse,
clamping is immediately released following ejection of the stay.
Ballistic insertion is normally guided visually, adjustment for the
delay of airgun chamber to treatment site transit time spontaneous
and the practical effect of inaccuracies insignificant.
[0773] Arteries are implanted on the pulse and the gastrointestinal
tract aside from any contractive wave. Unless tissue to the sides
is permitted to interfere with the passive resting of the tool on
the ductus, the stays enter to the correct depth without lifting or
downward force by the operator. Stay insertion tools are made in
different sizes and weighted for the median bearing force
ordinarily required to implant ductus of given types to
subadventital or subfibrosal depth. Certain positions, pathology,
and the use of attachments such as auxiliary syringes necessitate
adjustment in the weight or bearing force, which is applied by the
operator spontaneously or with the aid of a tonometer or pressure
gauge.
[0774] Greater precision in the size of adjustment to the passive
weight required can be achieved with the aid of a tonometer or
pressure gauge as described below in the section entitled In situ
test on extraluminal approach for proper stay insertion bearing
force. Since removing weights will not adjust for the weight of
attachments, the adjustment is applied with the aid of the same
force gauge used to conduct the test. To minimize inadvertent
changes in bearing force during tool actuation, the tool presents
the least resistance possible, and to allow the range of adjustment
necessary to treat ductus of given size and type regardless of
condition, control by test and touch, or if necessary, with the aid
of a pressure measuring device, is preferred to remote
triggering.
[0775] The difference in downward force to infix the stay to a
significantly greater depth is sufficiently large that the variance
in downward force resulting from the attachment of auxiliary
syringes and, unless excessive, that applied by the operator,
should rarely result in excessively adluminal insertion much less
penetration into the lumen. Remote actuation in order to avoid
excessive weight from being brought to bear down on the tool is
therefore unnecessary. If necessary, verification of depth can be
obtained with the aid of intravascular ultrasound; however, this
negates an advantage in the use of stays, which is complete
avoidance of the lumen.
[0776] Similarly, a catheteric device is not introduced into the
lumen to support the arterial wall from within. This is done,
however, in the gastrointestinal tract where entry is
nonincisional. In blood vessels, increased resistance to
compression can often be accomplished merely by pinching the ductus
without the trauma of entry. Since stay insertion is best timed to
the distention maxima or outward force exerted by the smooth
muscle, smooth muscle suppressive measures, whether relaxants,
cuffing, or clamping, are best avoided in arteries but may be
advantageous in the ureters or gastrointestinal tract.
[0777] Unless otherwise inadvisable, when the pulse is weak or the
artery sclerosed, as addressed below in the section entitled
Blood-grooves on Muzzle-heads for Use in Blood Vessels, medication
to raise the blood pressure is beneficial (see, for example,
McEniery, C. M., Yasmin, K., Maki-Petaja, M., McDonnell, B. J.,
Munnery, M., and 4 others 2010. "The Impact of Cardiovascular Risk
Factors on Aortic Stiffness and Wave Reflections Depends on Age:
The Anglo-Cardiff Collaborative Trial (ACCT III)," Hypertension
2010 56(4):591-597; Vyssoulis, G. P., Pietri, P. G., Karpanou, E.
A., Vlachopoulos, C. V., and 4 others 2010. "Differential Impact of
Metabolic Syndrome on Arterial Stiffness and Wave Reflections:
Focus on Distinct Definitions," International Journal of Cardiology
138(2):119-125; Haynes, F. W., Ellis, L. B., and Weiss, S. 1936.
"Pulse Wave Velocity and Arterial Elasticity in Arterial
Hypertension, Arteriosclerosis, and Related Conditions," American
Heart Journal 11(4):385-401; Bramwell, J. C. McDowall, R. J. S.,
and McSwiney, B. A. 1923. "The Variation of Arterial Elasticity
with Blood Pressure in Man (Part I)," Proceedings of the Royal
Society of London. Series B, 94(656):i-vi).
[0778] Ballistic insertion, from within the ductus, is timed
reciprocally for the maximum resistance looking radially outward.
Peristaltic action is usually slow enough to allow insertion with
stays or miniballs without drugs (spasmolytics, antispasmodics,
antispasmogenics--loperamide, salbutamol, co-phenotrope,
dicyclomine, hyoscyamine, propantheline bromide, atropine sulfate,
and opioids). When the onset time of the drug allows, the procedure
may commence with the implanting of stays or miniballs that consist
of or include this medication. If necessary, the rate and force of
peristalsis can be adjusted. Adjustment in the rate and force of
peristalsis may be necessary to achieve precise placement during
ductus-intramural implantation or to propel drug carrier
nanoparticles, for example, past less to more strongly magnetized
impasse-jackets placed at intervals along the tract.
[0779] Adjustment takes the form of medication, which can be
locally introduced in a targetd manner by injection syringe
tool-inserts or as medication miniballs, for example, or the
introduction of contents into the lumen. In the digestive tract,
the latter will usually involve simply ingesting ordinary food
supplemented to include agents that support the procedure. Whether
in the gastrointestinal tract, ureters, or gamete transport
conduits, peristalsis is rarely so fast as to interfere with
miniball discharge when adequate viewing means are present, or stay
insertion using touch. When the ductus is manipulable, merely
handling it will often suppress peristalsis. Arresting movement in
any ductus through upsteam clamping should not be necessary.
Ateries can usually be clamped long enough for each stay to be
inserted.
[0780] Applied from within the lumen, ballistic implantation
preparatory to the placement of a magnetic stent allows
prepositioning of the stent-jacket, which can then serve as a
motility restraining mantle or cuff; the stent-jacket side-straps,
or belt-straps, are tightened only so long as it is necessary to
prevent the slide-slit or side-slot from opening in response to the
pulse. Once implantation has been completed, the barrel-assembly is
withdrawn and the fabric backed hook and loop (such as Velcro.RTM.,
made by the firm of the same name) belt-straps loosened or cut off
to allow the side-slit or side-slot to comply with the pulse. For
ballistic implantation, cuffing in this manner is better than
clamping, because it eliminates movement of the lumen wall without
completely cutting off circulation past the cuff as well as
protects against the possibility of a perforation if the exit
velocity has been set too high.
[0781] The use of a cuff to suppress a problematic pulse requires
that the muzzle-head be small enough in diameter to allow some
blood to move past it through the stent-jacketed segment containing
the muzzle-head while tightened without injury to the lumen wall.
Adenosine and various drugs, such as esmolol allow slowing the
pulse, others slow peristalsis, and opioids can stop peristalsis
outright. Such a drug can be introduced into the lumen wall as a
stay, radial projection unit injection tool-insert injectant, or
fully absorbable medication miniball preceding stenting
implantation proper. In a bypass-angioplasty mixed procedure where
the chest is open, the use of a stabilizer apparatus is standard,
and a coronary artery can usually be further stabilized by lifting
it away from the surface of the heart and securing it in position
with tape or stitches.
[0782] When the pulse is erratic, one way to avoid the use of
circuitry to automatically synchronize discharge to the pulse
during automatic (machine-controlled) discharge in an artery is to
make the incision for inserting the stent-jacket prior to
discharge, then using a mosquito (Halsted, Kelly, Rochester)
forceps or hemostat, for example, to compress or clamp the artery
only so much and briefly enough to suppress the pulse. This is not
recommended when a barrel-assembly is used to implant medication
and/or other therapeutic substance-containing miniballs, which does
not necessitate outside access or incision at any time to place
implants which are completely absorbed.
[0783] The use of stays necessitates access by means of a local
incision in any event. Initiating a .beta..sub.1- or
cardioselective beta-blocker (beta adrenergic blocker), such as
atenolol (Tenormin.RTM.); a calcium channel blocker, such as
diltiazam (Cardizem.RTM., Dilacor.RTM.) or verapamil (Calan.RTM.,
Isoptin.RTM.); or digoxin (Lanoxin.RTM.) over the period
preparatory to the procedure serves to moderate a problematically
fast or erratic heart rate or high blood pressure (see, for
example, Landauer, A. A., Pocock, D. A., and Prott, F. W. 1979.
"Effects of Atenolol and Propranolol on Human Performance and
Subjective Feelings," Psychopharmacology 60(2):211-215).
[0784] 4e(2). Tissue Stabilization at the Treatment Site
[0785] 4e(2)(a). Temperature Stabilization
[0786] Thermal and cryogenic methods to include thermoplasty and
cryoplasty have long been used to remove diseased tissue. However,
subinjurious chilling of targeted tissue can also be used to
increase its mechanical and chemical, or metabolic, stability, that
is, reduce:
[0787] 1. The mobility (plasticity, deformability, nonfixation) of
soft tissue such as mucosal as a hindrance to shaving or abrasive
removal (Chick, H. and Lubrzynska, E. 1914. "The Viscosity of Some
Protein Solutions," Biochemical Journal 8(1): 59-69), and the rate
of chemical activity within the tissue (see, for example, Yang, W.
J. and Mochizuki, S. 2003. "Low Temperature and Cryogenic
Applications in Medicine and Surgery," in Kakac, S., Avelino, M. R.
and Smirnov, H. F. Low Temperature and Cryogenic Refrigeration,
Dordrecht Holland: Kluwer Academic Publishers).
[0788] 2. The magazine clip to slightly reduce miniballs in
diameter.
[0789] 3. The muzzle-head, or
[0790] 4. The entire barrel-assembly can be used to promote luminal
contraction about the muzzle-head as wll as reduce the rate of
metabolic activity in the cells.
[0791] Change in temperature, whether an increase or decrease,
stimulates smooth muscle to contract (see, for example, Tsai, C. S.
and Ochillo, R. F. 1989. "Low Temperature and Muscarinic Receptor
Activities," Cryobiology 26(5):485-95; Holzer, P. and Lembeck, F.
1979. "Longitudinal Contraction of Isolated Guinea-pig Ileum
Induced by Rapid Cooling," Naunyn-Schmiedeberg's Archives of
Pharmacology 310(2):169-174). Such contraction is usually transient
rather than sustained as seen in refractory vasospasm. Should
vasospasm ensue with the barrel-assembly endoluminal, nitrates
and/or calcium channel blockers can be locally injected by radial
projection unit injection syringe tool-inserts, service-catheter
hypotubes, or released along the internal surface of the lumen by
radial projection unit emission syringe tool-inserts or through an
available barrel-tube used as a service-channel
[0792] Local release allows targeting a much smaller amount of a
drug at a lesion in a much higher concentration than might be
administered systemically so that the entire body would be exposed.
In a harvested graft, contraction responsive to change in
temperature can be blocked with glyceryl trinitrate (apaverine and
calcium channel blockers less effective, and phenoxybenzamine
ineffective) (Oo, A. Y., Conant, A. R., Chester, M. R., Dihmis, W.
C., and Simpson, A. W. M. 2007. "Temperature Changes Stimulate
Contraction in the Human Radial Artery and Affect Response to
Vasoconstrictors," Annals of Thoracic Surgery 83(1): 126-132).
[0793] However, hypoxia or the release of endogenous prostanoids
may also effect a radial artery that has been harvested for a
coronary graft (Perrault, L. P. and Mommerot, A. 2007. "Invited
Commentary" [on Oo, Conant, et al. 2007, op cit. this paragraph],
Annals of Thoracic Surgery 83(1):132-133; see also Conant et al.
2003 in the section below entitled Risk of Abrupt Closure).
Reduction in temperature can be used to proportionally reduce the
rate of drug uptake. The chilling means described herein can be
used to lower the temperature of drugs delivered through injection
tool-inserts and hypotubes. Projection of the cold to the
surrounding lumen wall is prevented when preferred by using
insulated components.
[0794] For the insertion of stay implants from outside the ductus,
a cold air delivery catheter (thermal catheter, `cooling`-catheter)
whether connected to a CO.sub.2 cylinder or cold air gun, for
example, is easily fastened by means of the clips addressed below
in the section entitled Use of Stay Insertion Tool Side Mounting
Clips to Juxtaposition (Fasten Alongside) a CO.sub.2 Cylinder or
Cold Air Gun Line alongside the stay insertion tool. While the
sustained exposure of skin to a stream of pressurized CO2 will
result in frostbite, the momentary exposure of miniballs to
chilling during propulsion from this source is not significant.
[0795] Firming the target tissue and chilling, slightly reducing
the miniball in diameter, yields `cleaner` trajectories but may
require supplementation with a tumefaciant as addressed above in
the section entitled Ductus Wall Tumefacients. Together, these
measures will often make possible the implanting of a ductus wall
that would otherwise be too thin to implant at body temperature.
Heat-windows, the heating of turret-motor and recovery
electromagnet windings, `cooling` catheters (temperature changing
catheters which actually allow heating no less than cooling),
connection of a cold air gun, and so on are addressed below.
Discharge concurrent with thermal or cryogenic ablation or
angioplasty can be used to introduce medication.
[0796] 4e(2)(b). Removal of Vulnerable Plaque or Accreted Material
at the Implant Insertion Site
[0797] Except for protrusive angiosteosic (calcified) plaque which
must first be removed, the force of impact of the miniball is
sufficient to penetrate the lumen wall despite the presence of any
but stony intervening material, lumen contents, or contraction in
the lumen wall. However, the miniballs must enter without
delivering adherent matter in any significant degree and must be as
well positioned as possible. Minimizing if not averting
mispositioning due to the pulse or smooth muscular action is
addressed in the section immediately preceding. The force of impact
of the miniball is sufficient to penetrate almost any debris at the
lumen surface, certainly when harder debris has already been
removed by an angioplasty or an atherectomy.
[0798] A higher exit velocity averts a failure to penetrate or to
rebound (ricochet), and in most instances, the spherical contour
will minimize the adhesion and carrying forward into the lumen wall
of debris. The effect is minimal when the miniball has a metal
surface that is additionally wetted; however, when the miniball has
an outer surface that is deeply textured or tacky, it is possible
for its leading face to carry debris that was within or at the
internal surface of the lumen into the wall, although infected
blood would inoculate the wall in any event. The high exit velocity
of the miniball also minimizes exposure to the blood for adhesion
by clotting and militates against the adhesion of pathogens in
infected blood. Coatings of an antibiotic, antiviral, and
thrombolytic must follow from the clinical situation.
[0799] Combination-form barrel-asemblies use an edge-discharge
muzzle-head that unlike a center-discharge muzzle-head, makes the
central canal available. The central canal can permanently or
interchangeably channel an imaging device, commercially available
laser, or any of a number of atherectomy or thrombectomy devices.
In addition to the multiple components provided for atherectomy in
angioplasty-capable barrel-assemblies, the bores of
combination-form barrel-assemblies, as addressed below in the
section entitled Through-bore, or Combination-form,
Barrel-assemblies, and combination-form radial projection
catheters, as addressed in the section below entitled Through-bore,
or Combination-form, Radial Projection Catheters, allow the
insertion therethrough of various cabled atherectomy devices, to
include a laser or directional cutter, for example.
[0800] The use of either type combination-form significantly
increases the ability to minimize any residual debris or mineral
deposits, obtain a biopsy sample, or use the barrel-assembly as a
guide-catheter for administering medication, for example, without
the need to withdraw and reenter before initiating stenting
discharge. With respect to any ductus, the preliminary removal of
obstructive tissue from the lumen reduces the internal diameter of
the stent-jacket to which the wall must be outwardly retracted.
With arteries, a transluminal angioplasty or atherectomy
additionally reduces the risk of erosion or rupture of thin-capped
fibroatheromatous plaques with the release of potentially
embolizing debris.
[0801] Less forceful retraction reduces interference with normal
smooth muscle function and increases the minimum magnetic field or
tractive strength exerted on the implants essential to preserve
patency. Ideally, the wall is not retracted beyond its quiescent or
diastolic diameter. Less forceful retraction also reduces the risk
of miniball pull-through or delamination, preserving the usability
of miniballs where otherwise, as in stenting without previous
angioplasty or atherectomy, wide stent-stays would be needed.
[0802] 4f. Abrupt Closure with Thrombus and Vasospasm
[0803] 4f(1). Risk of Abrupt Closure with Thrombus and
Vasospasm
[0804] Abrupt closure can result in infarction, necessitate
emergency bypass surgery, and result in death. The use of prior art
apparatus and methods results in mid or postprocedural abrupt
closure in some four percent of angioplasties and atherectomies
overall. Following incisions caused by balloon overinflation,
abrupt closure results when a loose flap suddenly occludes the
lumen, whereas following directional atherectomy, for example,
obstruction usually results from the formation of a thrombus (see,
for example, Topol, E. J. 2003. Textbook of Interventional
Cardiology, Philadelphia, Pa.: Saunders, pages 528-530). The
muzzle-head is slippery and blunt-nosed so as not to catch, snag,
or gouge, making incisions improbable, and the use of medication to
control clotting should further reduce if not eliminate the risk of
abrupt closure.
[0805] Most vasospasms and outer diametrical contracture is found
with incipient atherosclerosis (Hong, M. K., Park, S. W., Lee, C.
W., Ko, J. Y., Kang, D. H., Song, J. K, Kim, J. J., Mintz, G. S.,
Park, S. J. 2000. "Intraductal Ultrasound Findings of Negative
Arterial Remodeling at Sites of Focal Coronary Spasm in Patients
with Vasospastic Angina," American Heart Journal 140(3):395-401).
Antiproliferative medication to treat atheromas or neoplasms that
induce vasospasm unresponsive to nitrates (nitrovasodilators), such
as nitroglycerin, or glyceryl trinitrate, and calcium channel
blockers (see, for example, The Merck Manual of Diagnosis and
Therapy, 18th Edition, page 599) usually require stenting.
[0806] With balloon angioplasty, arterial dissections occurr more
frequently with calcified plaques (see Potkin, B. N., Keren, G.,
Mintz, G. S., Douek, P. C., Pichard, A. D., Satler, L. F., Kent, K.
M., and Leon, M. B. 1992. "Arterial Responses to Balloon Coronary
Angioplasty: An Intravascular Ultrasound Study," Journal of the
American College of Cardiology 20(4):942-951), making beneficial
the removal of such plaque with an ultrasonic catheter or
rotational atherectomizer, which can be incorporated into a
combination-form barrel-assembly, as addressed below in the section
entitled Comparison with Prior Art Angioplasty. These conditions
should be treatable with less injury to the vessel by extraluminal
stenting.
[0807] Vasospasm can lead to more serious consequences than angina
and can kill even in the absence of arterial disease (see, for
example, Alcalde, O., Domingo, E., and Figueras, J. 2010.
"Recurrent Severe Acute Pulmonary Edema Caused by Transient Left
Ventricular Insufficiency with Mitral Regurgitation Related to
Severe Coronary Artery Spasm," Circulation. Heart Failure
3(2):332-335; Igarashi, Y., Tamura, Y., Suzuki, K., Tanabe, Y.,
Yamaguchi, T., Fujita, T., Yamazoe, M., Aizawa, Y., and Shibata, A.
1993. "Coronary Artery Spasm is a Major Cause of Sudden Cardiac
Arrest in Survivors without Underlying Heart Disease," Coronary
Artery Disease 4(2):177-185). The use of a balloon is suspected
also to evoke postprocedural vasospasm, or vasoconstriction
(Fischell, T. A., Nellessen, U., Johnson, D. E., and Ginsburg, R.
1989. "Endothelium-dependent Arterial Vasoconstriction after
Balloon Angioplasty," Circulation 79(4):899-910; Fischell, T. A.,
Derby, G., Tse, T. M., and Stadius, M. L. 1988. "Coronary Artery
Vasoconstriction Routinely Occurs after Percutaneous Transluminal
Coronary Angioplasty. A Quantitative Arteriographic Analysis,"
Circulation 78(6):1323-1334), with injury to the smooth muscle of
the media (Fischell, T. A., Grant, G., and Johnson, D. E. 1990.
"Determinants of Smooth Muscle Injury during Balloon Angioplasty,"
Circulation 82(6):2170-2184).
[0808] As addressed below in the section entitled Strengths and
Weaknesses of Prior Art Stenting in Vascular, Tracheobronchial, and
Urological Interventions, conventional endoluminal stents (see, for
example, Celik, T., lyisoy, A., Yuksel, U. ., Bugan, B., and Ersoy,
I. 2009. "Stent-edge Vasospasm after Bare Metal Stent Implantation:
A Case Report and Review of the Literature," Gulhane Tip Dergisi
51:174-176; Wong, A., Cheng, A., Chan, C., and Lim, Y. L. 2005.
"Cardiogenic Shock Caused by Severe Coronary Artery Spasm
Immediately after Coronary Stenting," Texas Heart Institute Journal
32(1):78-80), and not just those drug-eluting (see, for example,
Tomassini, F., Varbella, F., Gagnor, A , Infantino, V., Luceri, S.,
and Conte, M. R. 2009. "Severe Multivessel Coronary Spasm after
Sirolimus-eluting Stent Implantation," Journal of Cardiovascular
Medicine (Hagerstown) 10(6):485-488; Brott, B. C., Anayiotos, A.
S., Chapman, G. D., Anderson, P. G., and Hillegass, W. B. 2006.
"Severe, Diffuse Coronary Artery Spasm after Drug-eluting Stent
Placement," Journal of Invasive Cardiology 18(12):584-592; Togni,
M. and Eberli, F. R. 2006. "Vasoconstriction and Coronary Artery
Spasm after Drug-eluting Stent Placement," Journal of Invasive
Cardiology 18(12):593), are used to suppress vasospasm (see, for
example, Van Spall, H. G., Overgaard, C. B., and Abramson, B. L.
2005. "Coronary Vasospasm: A Case Report and Review of the
Literature," Canadian Journal of Cardiology 21(11):953-957), but,
as can guide wires, induce vasospasm on insertion, and those
drug-eluting, well afterwards.
[0809] While an endoluminal stent can sometimes control spasm (see,
for example, Warner, J. J. and Bashore, T. M. 2001. "Diagnostic and
Interventional Cardiac Catheterization," in Estafanous, F. G.,
Barash, P. G., and Reves, J. G. (eds.), Cardiac Anesthesia:
Principles and Clinical Practice, Philadelphia, Pa.: Lippincott
Williams and Wilkins, page 136), one implanted to suppress a
refractory spasm constrains the spasm up to its distal margins,
inflicting injury and endothelial dysfunction (see, for example,
Celik, T. et al. 2009 op cit.). Atheromatous lesions increase the
odds for aneurysm and vasospasm, and are the direct cause of
negative remodeling. In negatively remodeled arteries following the
removal of diseased tissue by the means described herein, smooth
muscle proliferation, or neointimal hyperplasia (see, for example,
Guerin, P., Rondeau, F., Grimandi, G., Heymann, M. F., and 6 others
2004. "Neointimal Hyperplasia after Stenting in a Human Mammary
Artery Organ Culture," Journal of Vascular Research 2004
41(1):46-53), should be less than tends to ensue following balloon
angioplasty.
[0810] While vasospasm is commonly associated with abrupt closure
(see, for example, Fischell et al. 1989 op cit.), it can arise as a
separate entity, even remotely from the treatment site (see, for
example, Tomassini, F., Varbella, F., Gagnor, A., Infantino, V.,
Luceri, S., and Conte, M. R. 2009. "Severe Multivessel Coronary
Spasm after Sirolimus-eluting Stent Implantation" Journal of
Cardiovascular Medicine (Hagerstown) 10(6):485-488; Tani, S.,
Watanabe, I., Kida, T., Ishikawa, K., Iida, K., and 7 others 2005.
"Unexpected Coronary Vasospasm of a Contralateral Artery during
Balloon Angioplasty" Heart and Vessels 20(2):82-84) and therefore
remains as a threat.
[0811] Vasospasm is usually alleviated by nitrates and calcium
channel blockers; however, when not prevented, vasospasm can
disable a magnetic stent by delamination of the vascular tunics or
pull-through, that is, the perforation of a miniball or miniballs
through the adventitia resulting in a loss of lumen-patenting
retraction. The risk of incisions by a muzzle-head of unsuitable
size or of thrombosis as the result of introducing small punctures
and narrow trajectories through the intima and media should be
significantly less than it is with the guide wires and the
catheteric means in conventional use. Because the lumen is never
entered, medication stays or stent-stays implanted without an
angioplasty avoid the risk of thrombosis. Antithrombic medication
administered to protect against accidental perforation into the
lumen is can be delivered locally as a coating on the stays rather
than systemically as could create a problem with bleeding.
[0812] Similarly, using miniballs, the puncture sites are
thrombogenic; however, miniballs coated with antithrombogenic
medication should allow significant reduction in the systemic dose.
The propensity for abrupt closure with or without thrombogenesis
and/or reflexive recoil or spasm responsive to ballistic entry if
any, with and without preprocedural administration of nitrates and
calcium channel blockers, for example, has not been established.
The availability of numerous spasmogenic drugs notwithstanding, the
range of actual or absolute forces generated in vasospasm with and
without various drugs having been administered is unaddressed in
the literature, probably because nitroglycerin succeeds in
suppressing most spasm. Anti spasmodics for use in other type ducti
include beladonna in the gastrointestinal tract and hyocine in the
biliary and urinary as well as the gastrointestinal tract, for
example.
[0813] Chemically mediated within the wall (see, for example,
Humphrey, J. D., Baek, S., and Niklason, L. E. 2007.
"Biochemomechanics of Cerebral Vasospasm and Its Resolution: I. A
New Hypothesis and Theoretical Framework," Annals of Biomedical
Engineering. 35(9):1485-1497 and "II. Constitutive Relations and
Model Simulations," 35(9):1498-1509), vasospasm may be forcibly
resisted by an endoluminal stent, but not without trauma at the
margins. Neither is mitigation in remodelling and the vasospasm
that remodelling is suspected to engender (see, for example, Zhang,
Z. D. and Macdonald, R. L. 2006. "Contribution of the Remodeling
Response to Cerebral Vasospasm," Neurological Research
28(7):713-720; Hong, M. K., Park, S. W., Lee, C. W., Ko, J. Y.,
Kang, D. H., Song, J. K, Kim, J. J., Mintz, G. S., Park, S. J.
2000. "Intraductal Ultrasound Findings of Negative Arterial
Remodeling at Sites of Focal Coronary Spasm in Patients with
Vasospastic Angina," American Heart Journal 140(3):395-401) to be
expected.
[0814] Complete dependency upon any kind of stent to control
continued spasm such as of variant angina that persists past
eradication of the lesion or lesions with which it is associated is
likely to result in trauma to the artery if not failure of the
stent, the need for lifelong maintenance medication indicated. An
extraluminal stent intended to resist spasmodic constriction
without delamination or pull-through is best full-round with the
intravascular (intraductal) component preferably cyanoacrylate
cement-coated wide stays placed more deeply adluminal than where
spasm is medically suppressible and not of immediate concern.
Placement subjacent (adluminally) with respect to the bulk of the
contractile tissue reduces the risks of delamination or
pull-through.
[0815] Only stays can be coated with cyanoacrylate cement prior to
implantation, although immediate followup injection by hypotube
service catheter or radial projection unit injection syringe
tool-insert allows such treatment with miniballs. Contrast dye is
essential to achieve proximity to the implant. Side-looking
(radially directed) injection tool-insert can also inject
nitroglycerin, for example. Miniballs can be coated with a solid
protein solder and a glyceryl trinitrate, for example, a brief
interval allowed for nitrate uptake, then the solder denatured
(liquified) by heat-windows in the muzzle-head. The heat-windows do
not approach the autoignition temperature of nitroglycerin, which
is 270 degrees Celsius or 518 degrees Fahrenheit, even before the
addition of desensitizing additives.
[0816] Medical preparations of nitroglycerin are effectively
nonexplosive. Broad stays coated with cyanoacrylate cement will
resist delamination, and miniballs coated with protein solder
pull-through, up to a certain restraining (radially outward
pulling) force, beyond which one of the other will disable the
stent; however, an extraluminal stent cannot fracture and migrate
as have endoluminal stents under the force of contraction that
drives the stent margins into the intima and can even crush the
stent. Rather than used to apply a coating of cement, the built in
stay insertion tool coating mechanism can be used to further cover
solder-coated stays with nitroglycerin ointment, for example.
[0817] A radially symmetrical extraluminal stent requires a slitted
or narrowly slotted fully encircling (complete, full-round)
stent-jacket, so that dissection to free the outside of the ductus
in order to place broad stays along the far (opposite, deep) side
should not necessitate additional dissection. Where an artery gives
off plunging branches to be left intact at intervals too small to
allow its rotation for proper positioning of the stay insertion
tool without the imposition of torsion trauma, miniballs are placed
in the far side. Segmented stent-jackets as addressed in the
section below entitled Sectional, or Chain-stents, Segmented and
Articulated, afford versatility in clearing plunging offshoots as
well as far-side running attachments.
[0818] 4f(2). Prevention of Abrupt Closure with Thrombus and
Vasospasm
[0819] While not a balloon, an ablation or angioplasty-capable
barrel-assembly can be equipped with radial projection unit blank
push-arm tool-inserts, addressed in the section below entitled
Comparison with Prior Art Angioplasty, among others, to exert
radially outward force when using a microwave probe (applicator,
antenna) or laser, for example. Such a cabled device can be built
into a noncombination-form barrel-assembly or temporarily inserted
in the central channel of a combination-form type. With balloon
angioplasty and to a lesser extent with rotational atherectomy
devices, abrupt closure usually results when a flap created by
incisions occludes the lumen, usually bolstered by thrombus and
spasmic contracture, or vasoconstriction.
[0820] Reducing if not eliminating the thrombus and spasm reduces
the obstruction. The risk of and amelioration of abrupt closure
when timy puncture wounds are placed in the intima and media of a
muscular artery must be taken into account. Stretching injury
(parectasia, parectasis) and dissections resulting from use of the
apparatus of invention are improbable; however, thrombus remains a
threat that justifies the use of a platelet blockade. The
preprocedural administration of systemic platelet blockade to avert
thrombogenesis, nitroglycerin or an alternative vasorelaxant as
specified below to avert spasm, and optionally, a thrombolytic, is
routine.
[0821] By insertion in the central channel, barrel-assemblies can
incorporate radiofrequency (Barry, K. J., Kaplan, J., Connolly, R.
J., Nardella, P., Lee, B. I., Becker, G. J., Waller, B. F., and
Callow, A. D. 1989. "The Effect of Radiofrequency-generated Thermal
Energy on the Mechanical and Histologic Characteristics of the
Arterial Wall in Vivo: Implications for Radiofrequency
Angioplasty," American Heart Journal 117(2):332-341), laser
(Cheong, W. F., Spears, J. R., and Welch, A. J. 1991. "Laser
Balloon Angioplasty," Critical Reviews in Biomedical Engineering
19(2-3):113-146), and microwave (Landau, C., Currier, J. W.,
Haudenschild, C. C., Minihan, A. C., Heymann, D., and Faxon, D. P.
1994. "Microwave Balloon Angioplasty Effectively Seals Arterial
Dissections in an Atherosclerotic Rabbit Model," Journal of the
American College of Cardiology 23(7):1700-1707; Nardone, D. T.,
Smith, D. L., Martinez-Hernandez, A., Consigny, P. M., Kosman, Z.,
Rosen, A., and Walinsky, P. 1994. "Microwave Thermal Balloon
Angioplasty in the Atherosclerotic Rabbit," American Heart Journal
127(1):198-203; see also the section below entitled System
Features) thermal angioplasty or thermoplasty devices claimed
capable of fusing or welding loose flaps, which along with other
benefits claimed would reduce if not eliminate the incidence of
abrupt closures.
[0822] The ability to target the area for treatment with
medication-coated implants midprocedurally, however, allows a
significant reduction in the preprocedural systemic dose. Placement
of the stent-jacket prior to introducing the barrel-assembly, which
is slippery and without projections, as addressed below in the
section entitled Circumstances Recommending the Use of a
Shield-jacket or Preplacement of the Stent-jacket, should also aid
in reducing if not eliminating the risk of mid or postprocedural
abrupt closure. Vasospasm due to Prinzmetal (variant, vasospastic)
angina that recurs well after angioplasty despite the eradication
of triggering plaque at the time of the procedure is primarily
controlled with nitrates.
[0823] Vasospasm as a factor contributing to abrupt closure (see,
for example, Kern, M. J. 2004. The Interventional Cardiac
Catheterization Handbook, Philadelphia, Pa.: Mosby Elsevier, pages
163-175; Landau, C., Lange, R. A., and Hillis, L. D. 1994.
"Percutaneous Transluminal Coronary Angioplasty," New England
Journal of Medicine 330(14):981-993; Lazzam, C., Forster, C
Gotlieb, A., Dawood, F., Schwartz, L., and Liu, P. 1992. "Impaired
Vascular Reactivity Following Angioplasty is Mainly Due to
Endothelial Injury," Experimental and Molecular Pathology
56(2):153-162; Laurindo, F. R., da Luz, P. L., Uint, L., Rocha, T.
F., Jaeger, R. G., and Lopes, E. A. 1991. "Evidence for Superoxide
Radical-dependent Coronary Vasospasm after Angioplasty in Intact
Dogs," Circulation 83(5):1705-1715) can be ameliorated if not
eliminated with an antispasmodic, or angiotonic relaxant
(vasodilator, angiotensin counteractant, angiorelaxant,
spasmolytic, hypotensive agent), such as nitroglycerin
(short-acting), isosorbide dinitrate (long-acting), verapamil,
adenosine, nitroprusside, papaverine or hydralazine
(apresoline).
[0824] Unless administered for a collateral purpose, the direct
targeting obtained through the use of coated stays or miniballs or
radial projection unit injection syringe tool-inserts in the
barrel-assembly muzzle-head or radial projection catheter allow the
elimination or a significant reduction in the preprocedural or
preparatory systemic dose. Miniballs and stays can be jacketed with
solid-state drugs, and through use of the exit-coating feature of
the stay insertion tool, stays can additionally be given a coating
of any drug in a semiliquid state. Stays with a deeply textured
surface are used to retain much of the coating even when insertion
is resistive. To resist if not avert vasospasm mid- and for an
interval post-procedurally, broad stays or miniballs implanted are
coated with one or more of these drugs for targeted delivery.
[0825] With transluminal approach, the use of side-looking
(radially directed) injection tool-inserts, as addressed below in
the section entitled Radial Projection Unit Tool-inserts, allows a
significant increase in a targeted dose of these drugs in liquid or
semiliquid form. The retractive field strength of a stent-jacket
must be kept less than would result in the extraction of the
miniballs through the adventitia or in the delamination of the
lumen wall. This strength may be less than that required to
maintain the vessel patent mid-spasm, so that the contractive force
of vasospasm which a stent-jacket can overcome must be limited.
When vasospasm is refractory or resistant to suppression by drugs,
broad stays coated with cyanoacrylate cement are preferred, because
these are subjacent to and bondable and attracted over the largest
area cutting through the lines of force.
[0826] Broad stays can therefore be subjected to stronger field
strengths without failure and are the most resistant to being
pulled through under the spasmic constrictive force (contractive
force of the spasm). Reduction in the effectively retractive field
strength also recommends application of relaxant medication to the
implants if not systemically. Means for testing the resistance to
delamination of the lumen wall and pullout through the adventitia
are addressed below in the section entitled Testing and Tests. The
use of a muzzle-head not so large in diameter as to stretch the
lumen wall as might a balloon and less occlusive should reduce in
incidence if not eliminate abrupt closures. While the
barrel-assembly remains endoluminal, the muzzle-head is positioned
to prevent any significant constriction, and the muzzle-head
remains within the segment until the circumferentially full
complement of miniballs has been placed.
[0827] As with endoluminal stenting, the stent itself can often
maintain patency once placed. Continued vasospasm that proves
refractory to routine thrombolytic and antispasmodic or
vasorelaxant medication and appears sufficiently strong to cause
pull-through or delamination leading to retractive failure is
treated with Bosentan.RTM. (Actelion Pharmaceuticals) (Krishnan,
U., Win, W., and Fisher, M. 2010. "First Report of the Successful
Use of Bosentan in Refractory Vasospastic Angina," Cardiology
116(1):26-28), and if nonextensive, may in some instancees justify
crushing or severing vasa vasora over a very limited segment before
stenting of any kind is abandoned.
[0828] In addition to intimal injury, abrupt closure is associated
with and medial injury and elevation in myocardial band (MB) serum
creatine kinase (CK, phosphocreatine kinase, creatine
phosphokinase) isoenzyme, and troponin T, but a cause or effect
relationship between abrupt closure and elevated CK-MB has not been
determined (Cavallini, C., Rugolotto, M., Savonitto, S. 2005.
"Prognostic Significance of Creatine Kinase Release after
Percutaneous Coronary Intervention," Italian Heart Journal
6(6):522-529). The prevention of a thrombogenic component in abrupt
closure is sought through the administration of drugs that can be
applied to the miniball and stay implants described herein or
prepared in liquid form for injection by means of injection
tool-inserts for targeted delivery, if necessary, in combination
with systemic administration which can then be of lower dose, the
highly localized concentration serving to reduce the risk of
bleeding problems.
[0829] Conventional antithrombogenic measures include the use of
antiplatelet (antithrombocyte) medication (platelet receptor
blockers, inhibitors; platelet antiaggregants, aggregation
counteractants), such as aspirin, clopidogrel, ticlopidine,
thienopyridines, and glycoprotein IIb/IIIa (gpIIb/IIIa, integrin
.alpha..sub.IIb.beta..sub.3) receptor antagonists or inhibitors,
such as abciximab, eptifibatide and tirofiban. In arteries,
clotting is less inhibited by anticoagulants, such as warfarin,
intravenous heparin (or argatroban, efegatran, inogatran,
napsagatran, fondaparinux, or idraparinux); while a spasmodic
component is suppressed with vasodilatory drugs, such as glyceryl
trinitrate (nitroglycerin), phenoxybenzamine, papaverine, and
calcium channel blockers, or antagonists, such as diltiazem,
verapamil, and nifedipine.
[0830] If refractory to calcium channel blockers, then (per
Skillings at http://www.medscape.com/viewarticle/413564)
amiodarone: (Rutitzky, B., Girotti, A. L., Rosenbaum, M. B. 1982.
"Efficacy of Chronic Amiodarone Therapy in Patients with Variant
Angina Pectoris and Inhibition of Ergonovine Coronary
Constriction," American Heart Journal 103(1):38-43), or if pregnant
or subject to become pregnant, the .alpha.2 adrenergic agonist
clonidine, or guanethidine (Frenneaux, M., Kaski, J. C., Brown, M.,
and Maseri, A. 1988. "Refractory Variant Angina Relived by
Guanethidine and Clonidine," American Journal of Cardiology 62(10
Part 1):832-833) is used.
[0831] Whether during or following an angioplasty, an atherectomy,
or stenting, that thrombogenesis is a central factor in abrupt
closure is attested to by the effectiveness of such antithrombotic
(antithrombogenic) drugs such as aspirin, abciximab, and
dipyridamole in reducing the gravity of this complication. (see,
for example, Heintzen, M. P., Heidland, U. E., Klimek, W. J.,
Leschke, M., and five other authors, 2000. "Intracoronary
Dipyridamole Reduces the Incidence of Abrupt Vessel Closure
Following PTCA: A Prospective Randomised Trial," Heart
83(5):551-556; Schillinger, M. and Minar, E. 2007. Complications in
Peripheral Vascular Interventions, London, England: Informa
Healthcare, page 190).
[0832] When angioplasty is opted against, the use of stays avoids
luminal entry entirely. Vasospasm, or vasoconstriction, induced by
endothelial injury are also implicated (see, for example, Lazzam,
C., Forster, C., Gotlieb, A., Dawood, F., Schwartz, L.,and Liu, P.
1992. "Impaired Vascular Reactivity Following Angioplasty is Mainly
Due to Endothelial Injury," Experimental and Molecular Pathology
56(2):153-162; Vassanelli, C., Menegatti, G., Zanolla, L.,
Molinari, J., Zanotto, G., and Zardini, P. 1994. "Coronary
Vasoconstriction in Response to Acetylcholine after Balloon
Angioplasty: Possible Role of Endothelial Dysfunction," Coronary
Artery Disease 5(12):979-986). Whether thermoplasty, cryoplasty, or
electrical discharge have any particular effect that would serve to
incite and predesensitize and thus suppress if not prevent abrupt
closure is elusive of a testing method and unaddressed in the
literature.
[0833] Using conventional apparatus, trauma responsive vasospasm
can arise as the result of a more extended dissection due to
balloon overinflation during angioplasty or with directional
atherectomy, where injury due to the bulkiness of older models of
such a device has been hypothesized to result in an increased rate
of distal embolization (Abdelmeguid, A. E., Whitlow, P. L., Sapp,
S. K., Ellis, S. G., and Topol, E. J. 1995. "Long-term Outcome of
Transient, Uncomplicated, In-laboratory Coronary Artery Closure
Circulation 91(11):2733-2741, whose attribution to spasm as weakly
predictive of acute sequelae compared to elevation in serum muscle
enzyme levels is at odds with the findings of Piana, R. N., Ahmed,
W. H., Chaitman, B., Ganz, P., Kinlay, S., Strony, J., Adelman, B.,
and Bittl, J. A. 1999. "Effect of Transient Abrupt Vessel Closure
During Otherwise Successful Angioplasty for Unstable Angina on
Clinical Outcome at Six Months," Journal of the American College of
Cardiology 33(1):79-81) in both instances, especially when
insufficient glycoprotein IIb/IIIa antagonist (inhibitor) has been
administered to deter platelet-rich thrombi.
[0834] When the object of the procedure is to stent the vessel,
abrupt closure at levels (stretches, segments) beyond that to be
stented poses the greater risk. Based upon the occasional
appearance of an abrupt closure in an untreated artery, a certain
percentage of abrupt closures during angioplasty or stenting may be
unavoidable regardless of the apparatus used (see, for example,
Moukarbel, G. V. and Dakik, H. A. 2003. "Diffuse Coronary Artery
Spasm Induced by Guidewire Insertion," Journal of Invasive
Cardiology 15(6):353-354; Takahashi, M., Ikeda, U., Sekiguchi, H.,
Fujikawa, H., Shimada, K., and Ri, T. 1996. "Guide Wire-induced
Coronary Artery Spasm During Percutaneous Transluminal Coronary
Angioplasty. A Case Report," Angiology 47(3):305-309; additional
references, to include Lauribe et al. 1993, below in this
section).
[0835] However, plaque-crushing and/or circumferential fiber
tearing angioplasty is more likely to produce dissections and
induce coronary vasospasm than is touching the lumen wall, much
less in a different artery, with a guidewire, which is rare, and
vasodilators as specified below in this section are available to
ameliorate if not dispel vasospasm as a complication. The tiny
puncture wounds produced by the miniballs as these enter the intima
and the trajectories through the media are quite unlike dissections
in extent or form, and the barrel-assembly, while larger in
diameter than a balloon while uninflated, is fully rounded and
smooth surfaced as not to gouge, nor is it so large as to seize
onto or stretch the lumen wall.
[0836] Absent dissection that leads to an abrupt closure, balloon
(compressive, atheroma-crushing) angioplasty still injures the
endothelium, and "endothelial dysfunction can promote both
restenosis and coronary spasm" (Chandrasekar, B., Nattel, S., and
Tanguay, J. F. 2001. "Coronary Artery Endothelial Protection After
Local Delivery of 17Beta-Estradiol During Balloon Angioplasty in a
Porcine Model: A Potential New Pharmacologic Approach to Improve
Endothelial Function," Journal of the American College of
Cardiology 38(5): 1570-1576).
[0837] The injury produced by ballistic implantation or stay
insertion, which is discontinuous and small in extent, is
considerably less than that of intentional subintimal or of vessel
size-adapted angioplasty. A subintimal recanalization, or
percutaneous intentional extraluminal recanalization (or
revascularization) (PIER), which produces far larger puncture
wounds through the lumen wall, may be performed in a lower
extremity (such as in the iliac artery to salvage a kidney or leg)
even when, albeit difficult, a strictly endoluminal angioplasty is
possible.
[0838] Nevertheless, extraluminal recanalization is gaining in
acceptance relative to strictly endoluminal angioplasty, despite
the puncture wounds (see, for example, Scott, E. C., Biuckians, A.,
Light, R. E., Scibelli, C. D., Milner, T. P., Meier, G. H. 3rd, and
Panneton, J. M. 2007. "Subintimal Angioplasty for the Treatment of
Claudication and Critical Limb Ischemia: 3-year Results," Journal
of Vascular Surgery 46(5):959-964; Ko, Y. G., Kim, J. S., Choi, D.
H., Jang, Y., Shim, W. H. 2007. "Improved Technical Success and
Midterm Patency with Subintimal Angioplasty Compared to
Intraluminal Angioplasty in Long Femoropopliteal Occlusions,"
Journal of Endovascular Therapy 14(3): 374-381; Cho, S .K., Do, Y.
S., Shin, S. W., Park, K. B., Kim, D. I., Kim, Y. W., Kim, D. K.,
Choo, S. W., and Choo, I. W. 2006. "Subintimal Angioplasty in the
Treatment of Chronic Lower Limb Ischemia" Korean Journal of
Radiology 7(2):131-138; Mishkel, G. and Goswami, N. J. 2005. "A
Practical Approach to Endovascular Therapy for Infrapopliteal
Disease and the Treatment of Critical Leg Ischemia: Savage or
Salvage Angioplasty?," Journal of Invasive Cardiology
17(1):45-51).
[0839] Specific risks with `therapeutic dissections` and
size-adapted angioplasty are addressed below in the section
entitled Basic Strengths and Weaknesses of Prior Art Stenting in
Vascular, Tracheobronchial, and Urological Interventions.
"Cocktails" of verapamil, heparin, and nitroglycerin (Saland, K.
E., Cigarroa, J. E., Lang,e R. A., and Hillis, L. D. 2000.
"Rotational Atherectomy," Cardiology in Review 8(3):174-179) and
nicardipine and adenosine (Fischell, T. A., Haller, S., Pulukurthy,
S., and Virk, I. S. 2008. "Nicardipine and Adenosine "Flush
Cocktail" to Prevent No-reflow During Rotational Atherectomy,"
Cardiovascular Revascularization Medicine 9(4):224-228) recommended
for use during rotational atherectomy may suppress a tendency to
thrombogenic vasospasm with abrupt closure.
[0840] Essentially the same technique as a subintimal
recanalization, or percutaneous intentional extraluminal
recanalization (or revascularization) in a peripheral artery,
subintimal tracking and reentry is gaining acceptance for use in
coronary arteries that have become completely blocked Colombo, A.,
Mikhail, G. W., Michev, I., Iakovou, I., Airoldi, F., Chieffo, A.,
Rogacka, R., Carlino, M., Montorfano, M., Sangiorgi, G. M.,
Corvaja, N., Stankovic, G. 2005. "Treating Chronic Total Occlusions
Using Subintimal Tracking and Reentry: The STAR Technique,"
Catheterization and Cardiovascular Interventions 64(4):407-412) and
controlled antegrade and retrograde subintimal tracking (Katoh, O.
and Ogata, W. 2007. "Recanalizing Occluded Vessels Using Controlled
Antegrade and Retrograde Tracking," World Intellectual Property
Organization Patent WO/2007/095191; Surmely, J. F., Tsuchikane, E.,
Katoh, O., Nishida, Y., Nakayama, M., Nakamura, S., Oida, A.,
Hattori, E., and Suzuki, T. 2006. "New Concept for CTO [Chronic
Total Occlusion] Recanalization Using Controlled Antegrade and
Retrograde Subintimal Tracking: The CART Technique," Journal of
Invasive Cardiology 18(7):334-338).
[0841] At least as traumatizing as the apparatus and methods
described herein, atheromatous arteries have been claimed to
demonstrate the potential for recovery from the more severe
intraparietal, or ductus-intramural, laminar separations,
perforations, and dissections imposed by the preceding techniques
(Schroeder, S., Baumbach, A., Mahrholdt, H., Haase, K. K.,
Oberhoff, M., Herdeg, C., Athanasiadis, A., and Karsch, K. R. 2000.
"The Impact of Untreated Coronary Dissections on Acute and
Long-term Outcome after Intraductal Ultrasound guided PTCA,"
European Heart Journal 21(2):137-145 and 21(2):92-94; Schroeder,
S., Baumbach, A., Haase, K. K., Oberhoff, M., Marholdt, H., Herdeg,
C., Athanasiadis, A., and Karsch, K. R. 1999. "Reduction of
Restenosis by Vessel Size Adapted Percutaneous Transluminal
Coronary Angioplasty Using Intraductal Ultrasound," American
Journal of Cardiology 83(6):875-879) and adapt to sustained
forcible distention (Dirsch, O., Dahmen, U., Fan, L. M., Gu, Y. L.,
Shen, K., Wieneke, H., and Erbel, R. 2004. "Media Remodeling--The
Result of Stent Induced Media Necrosis and Repair," Vasa
33(3):125-129).
[0842] Comparative data for relative frequency of vasospasm
attendant upon arterial thermoplasty or cryoplasty do not appear in
the literature; however, considering spasm has been known to arise
where the vessel has not even been touched, endothelial injury due
to balloon compressive, atheroma-crushing angioplasty would appear
equally if not more likely to induce vasospasm. While rare, a
mechanical force exerted in an artery other than that treated (see,
for example, Lauribe, P., Benchimol, D., Duclos, F., Benchimol, A.,
Bonnet, J., Levy, S., and Bricaud, H. 1993. "Spasme occlusif d'une
artere coronaire non abordee au cours d'une angioplastie. A propos
d'une observation" ["Occlusive Spasm of a Coronary Artery Not
Treated During Angioplasty. Apropos of a Case"], Annales de
cardiologie et d'angeiologie 42(2):89-92) can induce spasm. Such an
aberration aside, spasm often follows stretching injury.
[0843] The mechanism has been hypothesized to involve the imparting
of hyper-reactivity to acetylcholine (Nishijima, H. Meno, H.,
Higashi, H., Yamada, K., Hamanaka, N., and Takeshita, A. 1996.
"Coronary Vasomotor Response to Acetylcholine Late After
Angioplasty," Japanese Circulation Journal 60(10):789-796; Osborn,
L. A. and Reynolds, B. 1998. "Vagally Mediated Multivessel Coronary
Artery Spasm During Coronary Angiography," Catheterization and
Cardiovascular Diagnosis 44(4):423-426), perhaps by relation to the
superoxide radical (see for example, Laurindo, F. R., da Luz, P.
L., Uint, L., Rocha, T. F., Jaeger, R. G., and Lopes, E. A. 1991.
"Evidence for Superoxide Radical-dependent Coronary Vasospasm after
Angioplasty in Intact Dogs," Circulation 83(5):1705-1715; Ferrer,
M., Tejera, N. Marin, J. and Balfagon, G. 1999. "Androgen
Deprivation Facilitates Acetylcholine-induced Relaxation by
Superoxide Anion Generation," Clinical Science 97(6): 625-631;
Rubanyi, G. M. and Vanhoutte, P. M. 1986. "Superoxide Anions and
Hyperoxia Inactivate Endothelium-derived Relaxing Factor," American
Journal of Physiology 250(5 Part 2):H822-H827). This is the likely
explanation for the occurrence of vasospasmodic response with
angioplasty even in another artery, much less when dissection has
not occured (see Fischell, T. A. 1990. "Coronary Artery Spasm After
Percutaneous Transluminal Angioplasty: Pathophysiology and Clinical
Consequences," Catheterization and Cardiovascular Diagnosis
19(1):1-3).
[0844] The causes for abrupt closure when using conventional means
aside, the appearance of vasospasm is usually deterrable through
the preprocedural inception of systemic arterial spasmodic
counteractive drugs, such as nitrovasodilators (glyceryl
trinitrate, nitroglycerin, intracoronary infusion of isosorbide
dinitrate) (see, for example, Moukarbel, G. V. and Dakik, H. A.
2003. "Diffuse Coronary Artery Spasm Induced by Guidewire
Insertion," Journal of Invasive Cardiology 15(6):353-354; Lauribe
et al. 1993, cited above), calcium antagonists (calcium channel
blockers), such as diltiazem (e.g., Cardizem.RTM., Dilzem.RTM.,
Herben.RTM., Viazem.RTM.) or verapamil (e.g., Bosoptin.RTM.,
Calan.RTM., Isoptin.RTM., Verelan.RTM.) (see, for example,
Pomerantz, R. M., Kuntz, R. E., Diver, D. J., Safian, R. D., and
Baim, D. S. 1991. "Intracoronary Verapamil for the Treatment of
Distal Microvascular Coronary Artery Spasm Following PTCA,"
Catheterization and Cardiovascular Diagnosis 24(4):283-285; Caputo,
M., Nicolini, F., Franciosi, G., and Gallotti, R. 1999. "Coronary
Artery Spasm after Coronary Artery Bypass Grafting," European
Journal of Cardiothoracic Surgery 15(4):545-548) or a dilute
intravenous solution of an opium alkaloid such as papaverine and a
calcium channel blocker such as nicardipine, as well as platelet
glycoprotein IIb/IIIa antagonist. Injection a local dose by means
of radial projection unit injection syringe tool-inserts allows
significant reduction if not elimination of the preprocedural
systemic dose. Alpha blocker antispasmodics include
phenoxybenzamine (Dibenzyline.RTM.), Doxazosin (Cardura.RTM.), and
Prazosin (Minipress.RTM.).
[0845] For reducing spasm in radial artery grafts, recent papers
incline toward a preference for verapamil-glycerine tri-nitrate
solution (see, for example, Attaran, S., John, L., and El-Gamel, A.
2008. "Clinical and Potential Use of Pharmacological Agents to
Reduce Radial Artery Spasm in Coronary Artery Surgery," Annals of
Thoracic Surgery (4):1483-1489; Yoshizaki, T., Tabuchi, N., and
Toyama, M. 2008. "Verapamil and Nitroglycerin Improves the Patency
Rate of Radial Artery Grafts," Asian Cardiovascular and Thoracic
Annals 16(5):396-400). Others find phenoxybenzamine preferable as
having prolonged duration of action (Kulik, A., Rubens, F. D.,
Gunning, D., Bourke, M. E., Mesana, T. G., and Ruel, M. 2007.
"Radial Artery Graft Treatment with Phenoxybenzamine is Clinically
Safe and May Reduce Perioperative Myocardial Injury," Annals of
Thoracic Surgery 83(2):502-509; Mussa, S., Guzik, T. J., Black, E.,
Dipp, M. A., Channon, K. M., and Taggart, D. P. 2003. "Comparative
Efficacies and Durations of Action of Phenoxybenzamine,
Verapamil/Nitroglycerin Solution, and Papaverine as Topical
Antispasmodics for Radial Artery Coronary Bypass Grafting," Journal
of Thoracic and Cardiovascular Surgery 126(6):1798-1805; Taggart,
D. P., Dipp, M., Mussa, S., and Nye, P. C. G. 2000.
"Phenoxybenzamine Prevents Spasm in Radial Artery Conduits for
Coronary Artery Bypass Grafting," Journal of Thoracic and
Cardiovascular Surgery 120:815-817).
[0846] Still others warn against the use of phenoxybenzamine (Pai,
R. K., Conant, A. R., and Dihmis, W. C. 2008. "Treatment with
Phenoxybenzamine May Lead to Loss of Endothelial Viability in
Radial Artery," Annals of Thoracic Surgery 86(1):350-351 in
response to Kulik et al. above with reply by author following;
Conant, A. R., Shackcloth, M. S., Oo, A. Y., Chester, M. R.,
Simpson, A. W. M., and Dihmis, W. C. 2003. "Phenoxybenzamine
Treatment is Insufficient to Prevent Spasm in the Radial Artery:
The Effect of Other Vasodilators," Journal of Thoracic and
Cardiovascular Surgery 126:448-454). The evidence implicates
lumen-obstructing flaps with thrombus as the primary cause of
abrupt closure with vasospasm an an aggravating but secondary
factor.
[0847] That abrupt closure is often accompanied by but never
reducible to vasospasm as might be induced by the sudden impact of
a projectile is also suggested by evidence that heparin
anticoagulation as measured by the activated clotting time appears
to reduce the risk of abrupt closure during angioplasty in
proportion to the dosage without increasing the risk of major
bleeding complications (Narins, C. R., Hillegass, W. B., Jr,
Nelson, C. L., Tcheng, J. E., Harrington, R. A., Phillips, H. R.,
Stack, R. S., and Califf, R. M. 1996. "Relation Between Activated
Clotting Time During Angioplasty and Abrupt Closure," Circulation
93(4):667-671; Bittl, J. A. and Ahmed, W. H. 1998. "Relation
Between Abrupt Vessel Closure and the Anticoagulant Response to
Heparin or Bivalirudin during Coronary Angioplasty," American
Journal of Cardiology 82(8B):50P-56P). The use of both heparin and
abciximab reduce the incidence of abrupt closure and implicate
thrombus as a factor.
[0848] However, with the sudden impact of a projectile, both
heparin anticoagulant-induced thrombocytopenia can remain threats
(see, for example, Ahmed, I., Majeed, A., and Powell, R. 2007.
Heparin Induced Thrombocytopenia: Diagnosis and Management Update,"
Postgraduate Medical Journal 83(983):575-582) and platelet blockade
nonanticoagulant-induced thrombocytopenia (see, for example,
Jubelirer, S. J., Koenig, B. A., and Bates, M. C. 1999. "Acute
Profound Thrombocytopenia Following C7E3 Fab (Abciximab) Therapy:
Case Reports, Review of the Literature and Implications for
Therapy," American Journal of Hematology 61(3):205-208).
[0849] The use of a direct thrombin inhibitor appears to reduce the
risk of this complication should it arise (see, for example, Gurm,
H. S. and Bhatt, D. L. 2005. "Thrombin, An Ideal Target for
Pharmacological Inhibition: A Review of Direct Thrombin
Inhibitors," American Heart Journal 149(1 Supplement):543-53; Di
Nisio, M., Middeldorp, S., and Buller, H. R. 2005. "Direct Thrombin
Inhibitors," New England Journal of Medicine 353(10):1028-1040,
erratum 353(26):2827; Arora, U. K. and Dhir, M. 2005. "Direct
Thrombin Inhibitors (Part 1 of 2)," Journal of Invasive Cardiology
17(1):34-38, "Direct Thrombin Inhibitors (Part 2 of 2),"
17(2):85-91; French, M. H. and Faxon, D. P. 2002. "Current
Anticoagulation Options in Percutaneous Intervention: Designing
Patient-specific Strategies," Reviews in Cardiovascular Medicine
3(4): 176-182).
[0850] In addition to systemic administration, miniballs can be
coated with antithrombogenic, anti-inflammatory, and/or intimal
hyperplasia-suppressing medication, for example, as described below
in the section entitled Medication (Nonstent) Implants and
Medication-coated Miniballs, Implants, and Prongs. The risk of
mortality and complications, to include cerebral hemorrhage, is
stated to be reduced the earlier coronary reperfusion is initiated
(Cannon, C. P. 2001. "Importance of TIMI-3 Flow," Circulation
104(6):624-626). Should such a response occur, miniballs with an
outer coating to deliver these drugs in situ are used, with any
collateral intravenous or oral dosage restricted to subhypotensive
levels. Counterintuitively, because it is instantaneous, clean,
bloodless, and limited to the tissue within and immediately
surrounding the trajectory, implantation by such means should
eventuate as minimally traumatizing with secondary swelling if any
moderate and manageable.
[0851] 4g. Emergency Recovery of Miniballs and Stays
[0852] The loss of a miniball into the lumen whether from the exit
port or recovery magnet miniball trap or antechambers at the front
of the muzzle-head is precluded both by the pull of the
electromagnets and the fact that the antechambers are closed off by
spring-loaded doors, and such an eventuality is immediately
arrestable and the miniball recoverable by magnetic interception
and recovery, as addressed in this section as well as several
others. When a trapped miniball could be lost due to brushing
against the lumen wall or due to jerking of the muzzle-head, the
resting field strength is increased. Miniballs and stays include
sufficient ferromagnetic content to allow retrieval regardless of
the inclusion thereof for drug-targeting and/or stenting.
[0853] If an immediate need for stenting is not evident, the
applicaton of a stent-jacket is deferred to a later procedure
contingent upon confirmation of the need therefor. When the
eventual need for a stent-jacket can be discounted with relative
confidence, the superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder content of the miniballs or
stays is to allow recovery and can be dispersed through the
miniball or stay in an absorbable matrix. The spherical form and
small size of a miniball, even one made entirely of a magnetic
stainless steel, for example, requires the use of a powerful
magnetic field in order to apprehend it.
[0854] When loss would pose a risk, medication miniballs discharged
for interspersal among stenting miniballs and stays positioned
likewise to be encircled within a stent-jacket, and radiation
seed-miniballs and stays to be encircled within a radiation
shielded stent-jacket must have sufficient ferromagnetic content to
allow retrieval but not so much as would induce pull-through or
delamination; recovery applies greater field strength than does
static traction. When the eventual need for a stent-jacket cannot
be discounted, the ferrous content of the miniballs or stays
preplaced initially should be nonabsorbably encapsulated, no
stent-jacket placed until a later procedure following confirmation
of the need therefor.
[0855] Broadly then, antiproliferative or chemotherapeutic
medication is delivered in the form of miniballs or stays that
preposition ferrous material for the eventual placement of a
stent-jacket, with no placement of a stent-jacket until the need
therefor has been confirmed. Once a miniball or stay with a deep
surface texture becomes infiltrated by and integrated into the
surrounding tissue, it is innocuous, and does not demand
extraction. If the threat of burning surrounding tissue during
essential magnetic resonance imaging arises, the stabilized
miniball is extracted by means of a sudden pulse from a powerful
external electromagnet. Nonabsorbed portions of miniballs or stays
can remain implanted indefinitely, so that precautionary
implantation never compels the placement of a stent-jacket not
otherwise required.
[0856] When, as in a smaller artery, the miniballs or stays cannot
be large or numerous enough to provide the dose-rate desired in
addition to the prepositioned ferrous cores, an irradiating
stent-jacket, as addressed below in the section entitled Radiation
Stent-jackets, is used. Briefly, in a radiation stent-jacket, which
can be provided with an absorbable surrounding shield as described
below in the section entitled Radiation Shield-jackets and
Radiation Shielded Stent-jackets Absorbable and Nonabsorbable, if
necessary, the seeds are bonded in interleaved or sandwiched
relation between the lining and the base-tube. Thus, in an artery,
a stent-jacket is used only when needed for retraction to
counteract shrinkage and/or for antiproliferative irradiation when
irradiating miniballs or stays would be too small and/or
numerous.
[0857] In descending order of preference, the six means provided
for preventing the loss of a miniball in the circulation are: 1.
The recovery electromagnets built into the muzzle-head of every
radial discharge barrel-assembly; 2. An impasse-jacket
prepositioned downstream from the treatment site; 3. The
coincidental presence of a downstream stent-jacket or magnet-jacket
that would seize the miniball in any event; 4. An external
electromagnet to intercept and if necessary, extract the miniball;
5. Aspiration through a barrel-tube or fluid operated aspiration
tool-insert, and 6. A run-ahead embolic trap-filter, which distal
to the nose of the muzzle-head, is well removed from the line of
discharge.
[0858] Midprocedurally, a downstream stent-jacket or magnet-jacket
allows endoluminal recovery with the recovery electromagnets in the
muzzle-head; however, unlike an impasse-jacket, these are not
configured to allow extraction with the aid of an external
electromagnet. This means that postprocedurally, a barrel-assembly
would have to be introduced to retrieve a miniball from within a
stent-jacket. Since a stent-jacket 1. Primarily serves to draw
stenting miniballs radially outward toward itself; 2. The miniballs
are introduced at an acute angle and seated subadventitially; and
3. The miniballs are conformed and treated for optimal integration
into and adhesion to the surrounding tissue, the odds that a
miniball would be released into the bloodstream postprocedurally
are slight. Nevertheless, different methods for intercepting and
retrieving a dropped miniball are addressed below.
[0859] Especially when a multiple discharge barrel-assembly is
used, an impasse-jacket should be prepositioned downstream to trap
any miniballs that enter the circulation. Midprocedurally,
miniballs or stays are normally retrieved with the recovery
electromagnets immediately present as built into the muzzle-head of
every barrel-assembly and stay insertion tool. Removal by recovery
electromagnet seizure directly from the lumen or from the
downstream impasse-jacket is preferred as completely endoluminal,
substantially atraumatic, and avoiding the need for transmural
extraction (through the lumen wall and out the side).
Impasse-jackets are dependable, but any barrel-assembly used to
remove a miniball from an impasse-jacket must have recovery
electromagnets with the field strength necessary to overcome the
hold of the impasse-jacket.
[0860] For postprocedural emergency recovery, the risk of trauma to
the ductus is minimized by prepositioning a miniball-impassable
collar, or impasse-jacket, downstream from the implantation site.
The postprocedural extraction of miniballs trapped in an
impasse-jacket, if necessary, is best accomplished with the aid of
an external electromagnet as the least complicated, noninvasive,
and quickest method; the use of a barrel-assembly then only
slightly less traumatic, an new entry incision and introducer
sheath required. Barring malfunctioning of the apparatus preferred,
the use of a spare barrel-tube or fluid tool-insert suction line to
recover a loose miniball through aspiration is not recommended as
awkward, undependable, and obscured by drawing in blood as
well.
[0861] While unlikely, the accidental introduction of a miniball
into the bloodstream by a barrel-assembly in use in another ductus
due to an airgun malfunction or human error is responded to by the
noninvasive extraluminal means for recovery next to be described.
For midprocedural emergency recovery under adverse circumstances,
such as when the ductus follows a deep and/or tortuous course, a
powerful and tightly focused external electromagnet is
prepositioned and when possible, pre-energized in addition to the
trap-jacket. Either the jacket or the electromagnet then stops the
miniball, with the external magnet used to extract the miniball
from the trap-jacket if necessary. Miniball-impassable jackets are
addressed below in the section entitled Miniball and
Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets.
[0862] Applied and positioned without luminal entry, stays are not
likely to enter the lumen, but may be defectively positioned.
Ordinarily, a mispositioned stay can be disregarded. However, means
must be provided for the removal of a stay that would detract from
or pose a risk to proper function. Stays not completely ejected
from the insertion tool can be retracted by the electromagnet built
into the tool for this purpose. If completely ejected into an
objectionable position, a more powerful extracorporeal
electromagnet is used to pull the stay into a safe location. That
miniballs, which tiny and spherical, can be extracted entirely
outside the body with little risk may be intuited, stays, have
pointed ends that would appear to require resituation to a safer
position inside the body.
[0863] However, stays are also tiny and while more incisive during
a forcible extraction than miniballs, are little capable of
imparting significant trauma. Stays and miniballs generally have a
surface texture to retain fluid coatings such as drugs and to
encourage tissue integration for positional stability.
Postprocedural extraction of miniballs associated with a
stent-jacket that has failed due to pull-through, or of miniballs
or stays where failure resulted from delamination so that the
implants remain inside the stent-jacket, require that the
stent-jacket be removed first, which must be accomplished
surgically. The use of wide stays coated with bonding agents such
as surgical cement or protein solder should make such occurences
rare.
[0864] Whereas a miniball that enters the lumen of a ureter, the
gut, or fallopian tube, for example, will usually not become
embedded in the lumen wall but be swept through and passed (voided)
without the need for intervention, one released into a blood vessel
will eventually reach its luminal diameter and occlude. When
miniballs are implanted in the wall of an artery, midprocedural or
postprocedural embolization must be prevented. To this end, an
impasse-jacket used as a trap- or guard-jacket is prepositioned
downstream. The noninvasive extraction of a miniball well before it
reaches the level of embolization mid or postprocedurally otherwise
requires the use of a powerful extracorporeal electromagnet, as
addressed below in section X2c entitled Stereotactic Arrest and
Extraction of a Circulating, Dangerously Mispositioned or
Embolizing Miniball.
[0865] The midprocedural and nonemergency postprocedural
interception and recovery by extraction, or evulsion, of miniballs
that escape into the bloodstream is noninvasive, an external
electromagnet used to withdraw the miniball through the lumen wall
and mesh to a safe location, as explained just below. Endoluminal
means for the recovery of miniballs mispositioned midprocedurally
are not only the recovery tractive electromagnets built into the
muzzle-head but include additional means summarized in the section
below entitled Use of the Barrel-assembly as an Aspirator or
Transluminal Extraction Catheter for the Removal of Soft Plaque or
Mispositioned Miniballs.
[0866] The pertinent apparatus is also covered in respective
sections directed to recovery electromagnets, trap-filters, and the
use of a free barrel-tube or service-channel for aspiration. While
medication miniballs that completely dissolve are uniformly seeded
with superparamagnetic magnetite or maghemite nanoparticles or
finely grained powder for midprocedural extraction or given a
ferromagnetic core, for optimized magnetic susceptibilty,
nonabsorbable stenting miniballs meant for long-term or permanent
implantation best include a prismoidal core. A miniball caught in
an impasse-jacket is noninvasively retracted to a safe location,
generally just outside the treatment ductus, by means of a powerful
external electromagnet.
[0867] When an angioplasty or atherectomy is unavoidable or the
circumstances recommend endoluminal treatment with miniballs rather
than stays, extraction is usually accomplished most quickly with
the recovery tractive electromagnets built into the muzzle-head.
Such circumstances may include an anomalous coronary artery that
tunnels through the subjacent myocardium to be bridged over by a
band of superjacent myocardium for more than 20 millimeters at a
depth of more than 5 millimeters (See, for example, Garde, P. S.,
Karandikar, A. A., Tavri, O. J., Patkar, D. P. and Dalal, A. K.
2006. "Tunneled CoronaryArtery: Case Report," Indian Journal of
Radiology and Imaging 16(3):283-284; additional references cited
below in the section entitled Considerations as to Access) or a
ductus that pursues a normal course through a connective sheath
that passes amid skeletal muscles as in the extremities.
[0868] When the degree of accuracy required for implantation is
uninvolved significantly reducing if not eliminating the need for
extraction, extraction by an extraluminal route is manipulatively
simpler and quicker. Except when the need for retrieval arises
midprocedurally with the barrel-assembly endoluminal, extraction
through the lumen wall is quicker to achieve, noninvasive, and less
susceptible to mishaps. Moreover, since the trajectory of
retraction is the same diameter as the miniball itself and
spontaneously closes in behind the passing miniball to seal the
tiny trajectory path, forcible extraction of a miniball through the
lumen wall to a safe location is not only noninvasive but minimally
traumatizing.
[0869] The diameters of the miniballs and impasse-jackets used to
treat a given ductus or segment thereof proportional in dimensions
and magnetic properties, unless the ductus wall is inordinately
resistant to perforation as with advanced sclerosis or hard
lesioning, the open mesh of an impasse-jacket is little larger than
the diameter of the the largest miniball placed upstream. For this
reason, the retractive force exerted on a miniball to be extracted
by an external electromagnet does not pull a significant area of
the ductus wall through the mesh stretching or notching it. Rather,
the tractive force is effective at the intended puncture site. This
results in a clean perforation, making nonendoluminal
(nontransluminal) approach preferable for recovery.
[0870] When no stent-jacket must be recovered, irradiating and
medication miniballs containing ferrous matter such as
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder for the express purpose of recovery may be retrieved
noninvasively through the application of a powerful external
magnetic field, stereotactic arrest and extraction used when
exceptionally necessary to avoid injury to structures along the
retraction path. The use of an external electromagnet to interdict
and/or extract a problem miniball is addressed below in the section
entitled Steering and Emergency Recovery of Implants with the Aid
of an External (Extracorporeal) Electromagnet. Miniballs for use
with a magnetic stent-jacket generally release neither radiation
nor drugs.
[0871] Whether implanting elemental superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder in the wall of a
ductus would in practice reach a level that resulted in a
functionally significant iron overload, hemosiderosis, or
hemochromatosis, or additional iron resulting from the
extravasation of erythrocytes from the vasa vasora of larger
arteries during insertion could produce such a result is unlikely.
Gold specified herein is not in compound form, is noble or
nonreactive, and without toxic potential. Since erroneously placed
ferromagnetic miniballs will seldom interfere with normal function,
those mispositioned in preparation to place a stent-jacket can
usually be left as is. The likelihood of mispositioning the
stent-jacket is slight, but provided with a moisture barrier-coated
viscoelastic polyurethane foam or other slide-resistant lining and
end-ties to prevent migration, the jacket will require reentry to
correct.
[0872] Outside the vascular tree, the miniature balls and stays to
be described can omit magnetic content when the use thereof for
retrieval will be unnecessary. The implants then consist purely of
medication, which can incorporate time-released layers, for
example, or radiation-emitting seeds coated with medication whether
multiple which is unaffected by the radiation. Conventional seeds
are not absorbed, but absorbable polymers can be coated or
impregnated with radioactive nuclides for complete absorption. Such
combinations are considered minor variants substantially consistent
with established pharmaceutical practice. Similarly, stent-jackets
are most often, but not always, of the magnetic type. In FIG. 1,
the relation shown between implants that attract or draw and those
attracted or drawn is often reversible; that the components in
either column may represent either the magnets or the components
attracted to the magnets is considered obvious.
5. Means for the Placement of Ductus-Intramural Implants
[0873] The intraductal elements consist of miniballs, placed with a
barrel-assembly, and arcuate stays, placed with a stay insertion
hand tool, all addressed below in the respective section of like
title. With sufficient ferrous content, miniballs and stays can
serve as the intraductal component of a magnetic extraluminal
stent; however, neither miniballs nor stays need have any relation
to stenting. Either type intraductal element can consist of
medication and/or other therapeutic substances, such as tissue
bonding, or surgical, cement, hardening (sclerotic), or swelling
(tumefacient) agents, and the nonintraductal implants described
herein can also be coated thus. For recoverability with the aid of
an external electromagnet if unintentionally released (dropped) or
mispositioned, virtually all of these implants, to include those
fully absorbable, contain some ferrous matter.
[0874] The luminal diameter, and if containing axially protrusive
hard (calcified, petrous, angiosteosic) matter, the degree of
luminal obstruction, will set a limit to the diameter of the
barrel-assembly that can pass, while the strength and tortuosity of
the ductus wall, if any, will determine how flexible the
barrel-assembly must be. The treatment required determining the
kind of radial projection units needed, both the limitation on
diameter and flexibility will determine whether the barrel-assembly
can be of the multibarrel type; or ensheathed within a matching
combination-form radial projection catheter, and/or be of the
combination-form type, and whether ensheathment can be accomplished
before rather than after the muzzle-head has been moved to the
treatment site.
[0875] To the extent that the foregoing determinants allow, radial
projection units of the kind and range of functional capability
needed can be integral to the muzzle-head, or the need for
bendability may require that a luminally size-matched
combination-form radial projection catheter be added after the
unsheathed barrel-assembly muzzle-head has been positioned at the
treatment site. Thus, small gauge lumina, those surrounded by weak
or tortuous walls, and those obstructed are first negotiated with a
barrel-assembly of small diameter having at least a thermoablating
heat-window at the nose. If rock-hard calcified plaque obstructs a
lumen too narrow to accommodate a combination-form barrel-assembly
with a rotational or linear cutter inserted, then a separate cutter
is used prior to insertion of the barrel-assembly. Less highly
calcified plaque can also be removed with an excimer laser or
ultrasonic probe. It will now be understood that any increment in
diameter and wall strength will admit of a significant increase in
the means described herein for treating the ductus.
6. Endoluminal Prehension of Miniballs and Ferrofluids
[0876] Impasse-jackets, addressed below in the section entitled
Concept of the Impasse-jacket and Miniball and Ferrofluid-borne
Particle-impassable Jackets, or Impasse-jackets among others, serve
primarily as downstream guard- or stopping-jackets to trap a loose
miniball or miniballs and thus interdict these from further passage
through the circulation. The impasse-jacket is designed to comply
with the intrinsic motility in the ductus and is placed to encircle
the ductus with minimal injury to the adventitia or fibrosa.
Circumferentially magnetized normal to its central axis and having
a cylindrical open mesh body, the impasse-jacket used as a
stopping-jacket allows a trapped miniball to be extracted with the
aid of an external electromagnet through the ductus wall to a
location outside the ductus with minimal trauma.
[0877] Other means for retrieving loose miniballs in the
circulation include the recovery electromagnets built into the
muzzle-head of the miniball implanting barrel-assembly itself, the
use of a prepositioned external electromagnet, and if so equipped,
the aspirators incorporated into the radial projection system.
Impasse-jackets also serve as holding jackets for suspending a
medication or radiation-emitting miniball in the lumen or for
attracting a drug or nucleotide-bound ferrofluid, for example,
within the lumen at the level desired. In order to direct the
medication into the arc containing the lesion to be treated, these
are more likely to incorporate asymmetrical magnetization; however,
their use as trap-jackets is unaffected, the trapped miniball or
miniballs directed to the arc of greater field strength.
[0878] Magnetic drug-targeting is addressed in the section above
entitled System Implant Magnetic Drug and Radiation Targeting and
in the sections below entitled Concept of the Impasse-jacket and
Miniball and Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets, among others. While the extraluminal stent
requires minor surgery to place, it is superior to an endoluminal
stent for the drawing drug carrier magnetized particles and
nanoparticles, because it leaves the lumen clear, can present a far
more powerful magnetic field than an endoluminal stent can achieve
within such a limited space, and outside the ductus pulls the
ferrofluid-bound drug into the lesion or neoplasm. With an external
extraction electromagnet, an accidental or idopathic overdose can
be withdrawn instantly through the mesh of the holding jacket.
[0879] Holding jackets are addressed below in the section entitled
Miniball and Ferrofluid-borne Particle-impassable-jackets, or
Impasse-jackets. Holding jackets allow medication miniballs
containing statin drugs, for example, to be suspended within the
bloodstream. In this way, treatment is targeted at the endothelium
within an artery, for example. Such dosing is generally repetitive
over a limited term, recommending the use of absorbable materials
that eliminate the need for recovery once placed through a small
incision. To leave no magnetized material once its useful life has
passed, the jacket mesh is made of an absorbable polymer and its
magnetization is of the polymer-incorporated biocompatible
particulate of which the mesh consists or is coated.
[0880] As addressed below in the section entitled Implants that
Radiate Heat on Demand, an impasse-jacket can also incorporate
means for generating heat when energized from outside the body.
Small-scale and substantially lesion-restricted drug-targeting
within a lesioned blood vessel, for example, allows drug
concentrations that if circulated would be toxic. Either the
endothelium or deeper layers can be targeted over a defined segment
in any of several ways. Treatment of the endothelium is by
positioning an impasse-holding jacket as an exit jacket to suspend
a miniball with a central core or distributed array of tissue
compatibly encapsulated ferrous matter at the end of the segment so
that the miniball dissolves to release a substance or substances
that directly disable or reverse, counteract, or neutralize the
drug or drugs injected or infused upstream at the start of the
segment.
[0881] In this case, magnetism serves only to retain the
neutralizing miniball in position, the drugs used conventional. The
drug targeting of a defined segment of a ductus or an organ is
addressed below in the section entitled Cooperative Use of
impasse-jackets in Pairs and Gradient Arrays, among others. To free
the patient from the clinic, the inception of the segment can also
be represented by an entry-jacket, which once implanted, can then
be made to retain a miniball suspended therein for breakdown and
the release of medication on demand such as when the patient
ingests a miniball-disintegrating or activating substance. When
necessary, the drug is self-administered by injection or infusion
through a subcutaneously implanted portal.
[0882] In the digestive tract, for example, contents are also
needed to carry the medication forward; when necessary to achieve
the necessary propulsive force relative to the degree of magnetic
susceptibility, the ductus may be injected with a substance to fill
it and/or accelerate or intensify the force of its motility.
Depending upon the function of the medication, however, dissolution
of the start of segment miniball may be too slow. Then accelerating
release from the entry jacket and/or activating the drug to
intensify or deactivating the drug to mollify its effect may
necessitate the addition of another agent by injection, infusion,
and/or heating by placement in an alternating magnetic field, for
example, conventionally tied to the clinic.
[0883] That miniballs or their contents in either or both entry and
exit jackets can be affected in the time of drug release or that
the properties of the therapeutic and if used, neutralizing drug
can often be adjusted in effective concentration, for example, by
introducing an additional agent or heat is obvious, as is the fact
that start of segment sites difficult to reach by direct injection
or infusion may warrant the preplacement of an entry-jacket. To
treat deeper or abluminal layers along a defined segment of a
ductus, usually a blood vessel, the medication introduced at the
start of the segment is locally injected as a ferrofluid or as
absorbable microspheres or miniballs containing drug carrier
particles or nanoparticles.
[0884] Since the drug-component is bound to the carrier particle,
the drug in such a ferrofluid is described as ferrobound and is
drawn to an impasse-jacket by relative strength of the vectors that
result from contents propulsion that would push the particles past
the impasse-jacket and the magnetic field strength which would
attract the particles, which is incrementally increased in the
antegrade direction. When the drug released from a disintegrating
miniball is intended for uptake into a lesion within the lumen wall
against the propulsive force of the lumen contents by attraction to
perivascular iimpasse-jackets, or is intended for uptake by an
organ that does not normally take up the drug or substance to which
the drug is bound, the drug is ferrobound.
[0885] By contrast, drugs confined but not combined with or bound
to the susceptible particlulate component in the ferrofluid,
microspheres, or shell of the miniball, for example, as to be
separated and carried forward when released are described as ferro
co-bound, which are not drawn to impasse-jackets. Drugs for
treating the internal surface of the lumen or an organ will often
be of this type without magnetic susceptibility. The use of an
absorbable drug-releasing endoluminal stent as the start of segment
drug release device is not preferred, primarily because of the
interference with intrinsic motility it causes and the sequelae to
which this can lead. While a more precise starting point
necessitates the preplacement of a microsphere or
miniball-suspending holding jacket, when accessible, direct
injection or infusion upstream from the first impasse-jacket is
used. The point of infusion or injection may not represent the
start of the segment to be treated but only the entry point for
loading or charging the entry-jacket.
[0886] When a ferrobound drug, for example, is released, the
initial fraction taken up by the entry jacket itself is that least
magnetically susceptible, each successive fraction targeted
distally more susceptible and/or each successive jacket moving
distad more strongly magnetized. So that to the extent possible
successive fractions will be drawn into the lumen wall by the
progressively stronger impasse-jackets encountered in the correct
proportion, the particles are graduated in magnetic susceptibility,
and if necessary, the jackets increased in strength of
magnetization. Used in these ways, impasse-jackets make possible
the targeting of a selectable segment, not just a focal point of a
ductus, and can accomplish this for magnetic drug-targeting using
ferrofluids and drug and/or radioactive miniball guidance on a very
small-scale.
[0887] A holding jacket for use to suspend microspheres or a
miniball will generally tend to concentrate the magnetization at
its longitudinal center, whereas one for use with ferrofluids will
generally be uniformly magnetized along its length. As but one
example of such use, statins (3-hydroxy-3-methylglutaryl coenzyme A
reductase inhibitors) are suspected by some to reduce the
inflammation of atherosclerosis through mechanisms not dependent
upon a reduction in serum cholesterol or triglycerides, and in so
doing, are accepted to preserve the remaining kidney function in
diabetics. The application of holding jackets to the use of statins
is addressed below in the section entitled Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays. Atherosclerosis is a
systemic condition that will usually call for a background systemic
dose of the statin; however, the ability to target acute lesions
has therapeutic value.
7. Comparison with Prior Art Angioplasty
[0888] Crushing plaque and subjecting the luminal wall to
stretching injury, conventional balloon angioplasty promotes
neointimal hyperplasia and medial cell proliferation, which the
irritation of an endoluminal stent probably increases. The methods
and apparatus described herein are intended to reduce
reinflammation, lesioning, and restenosis. Compliant with intrinsic
expansion and contraction, and not excessively distending the
ductus to preclude migration, an extraluminal stent is not a
chronic irritant that promotes reocclusion and is susceptible to
clogging. Removing most if not all of the stimulus to restenosis
can be further supported through the use of medicated or
time-released medicated ductus-intramural implants, or
lesion-targeted injection using syringe injector tool-inserts, as
will be described.
[0889] The higher concentration of drugs than might be introduced
into the systemic circulation allowed by the drug targeting means
described herein should reduce the need for stenting of any kind.
By avoiding balloon injury to an artery as may result in
inflammation entirely through its wall, an atherectomy performed by
the means to be described facilitates treatment by the extraluminal
stenting means to be described, which include stent-stays and
clasp-wraps that avoid the lumen entirely. Balloon angioplasty
compresses soft atheroma more than hard plaque, leaving an
irregular surface that induces turbulent flow increasing
thrombogenicity. The compressed tissue often `recoils,` that is,
resiliently re-expands, to partially re-obstruct the lumen.
[0890] To this partial closure is then added the intimal
hyperplasia induced by balloon stretching injury (see, for example,
Luo; H., Nishioka; T., Eigler; N. L., Forrester; J. S., Fishbein;
M. C., Berglund; H., and Siegel, R. J. 1996. "Coronary Artery
Restenosis after Balloon Angioplasty in Humans is Associated with
Circumferential Coronary Constriction," Arteriosclerosis,
Thrombosis, and Vascular Biology.16(11):1393-1398; Currier, J. W.
and Faxon, D. P. 1995. "Restenosis after Percutaneous Transluminal
Coronary Angioplasty: Have We Been Aiming at the Wrong Target?,"
Journal of the American College of Cardiology 25(2):516-520), and
the degree of closure becomes significant even without completion
by an embolism (atheroembolism). Balloon stretching can produce
restenosis, incisions, abrupt closure, and vasospasm.
[0891] Whereas the conventional reduction of obstructive tissue
within arteries by balloon angioplasty differs from the ablative
means conventionally used with other type ductus, the inventive
apparatus consistently ablates obstructive tissue in arteries as
well by any of a number of means to include thermoplasty,
curettage, and cryoplasty. The newer devices for use in arteries
which actually ablate rather than merely crush atheromatous
lesions, such as cutting balloons, rotational atherectomizers,
directional atherectomizers, and excimer lasers, have become
several, but require that the angioplasty be completed in an
initial transluminal pass before reentry to stent can commence.
[0892] Neither do these allow the targeted application of
medication or other agents to or into the luminal wall, much less
during angioplasty or stenting. Means for performing a thermal
angioplasty (thermoplasty, thermocautery angioplasty) are
incorporated into angioplasty-capable barrel-assemblies and radial
projection catheters and can be incorporated into minimally
angioplasty-capable barrel-assemblies. The object is to prevent the
erosion of fibrous plaque exposed to low density lipoprotein heavy
blood that would prove thrombogenic or release embolizing debris on
rupturing vulnerable plaque.
[0893] A preemptive pass, preferably not separate but integrated,
is performed at 85 to 90 degrees centrigrade to destroy the plaque
and its contents by cautery (Post, M. J., de Graaf-Bos, A. N.,
Posthuma, G., de Groot, P. G., Sixma, J. J., and Borst, C. 1996.
"Interventional Thermal Injury of the Arterial Wall: Unfolding of
von Willebrand Factor and Its Increased Binding to Collagen After
55 Degrees C[elsius] Heating," Thrombosis and Haemostasis
75(3):515-519; Nardone, D. T., Smith, D. L., Martinez-Hernandez,
A., Consigny, P. M., Kosman, Z., Rosen, A., and Walinsky, P. 1994.
"Microwave Thermal Balloon Angioplasty in the Atherosclerotic
Rabbit," American Heart Journal 127(1):198-203). Preferably, the
cautery is accomplished in the same pass as any other therapeutic
process the radial projection catheter or barrel-assembly is used
for.
[0894] This temperature is based upon the literature, and if in
need of correction, the content hereof is not dependent thereupon.
A distal embolic trap-filter to catch debris is redundant but can
be used if deployed far enough ahead of the nose heat-window.
Angioplasty-capable barrel-assemblies can also accept connection to
sources of cold fluid to perform a cryoplasty through service
catheters passed through barrel-tubes and/or fluid-operated
tool-inserts. Angioplasty systemic, a preemptive pass as continuous
or applied to sites of vulnerable plaque is addressed below in the
section entitled Thermal Ablation and Angioplasty- (Lumen Wall
Priming Searing- or Cautery-) Capable Barrel-assemblies.
[0895] Endothelial dysfunction and atherosclerosis as an
inflammatory process both systemic, function is impaired on
presentation, leaving the issue of the extent of impairment or
additional impairment to result from treatment problematic. The
ablation and angioplasty means provided herein include radially
outward-directed or side-looking cutting, heating (thermoplasty),
and chilling (cryoplasty) radial projection unit tool-inserts or
canisters attachable to the barrel-assembly or to the radial
projection assembly, and barrel-assembly-incorporated excimer
(excited dimer) lasers or rotatatory blade atherectomizers,
described in sections to follow. If not inherently eradicated by
such means, removed tissue is aspirated or trapped beneath the
cutting tool.
[0896] By contrast, conventional balloon angioplasty does not
remove but rather redistributes plaque to clear a passageway or
channel through the lumen by crushing the plaque between the
endothelium and the internal elastic lamina, injuring both (see,
for example, the background section in Chigogidze, N. A. 1997.
"Device and Method for Dynamic Dilation of Hollow Organs with
Active Perfusion and Extraction," U.S. Pat. No. 5,695,508) and
inducing luminally obstructive cell proliferation, consisting
primarily of intimal hyperplasia (see, for example, Harnek, J.,
Zoucas, E., Stenram, U., Cwikiel, W. 2002. "Insertion of
Self-expandable Nitinol Stents without Previous Balloon Angioplasty
Reduces Restenosis Compared with PTA Prior to Stenting,"
Cardiovascular and Interventional Radiology 25(5):430-436).
[0897] Rotational atherectomy, which can be incorporated into a
combination-form barrel-assembly or a radial projection catheter,
as addressed below in sections of like title, not only allows the
removal of higly calcified plaque, but is claimed to stimulate
intimal hyperplasia to a lesser degree (McKenna, C. J., Wilson, S.
H., Camrud, A. R., Berger, P. B., Holmes, D. R. Jr., and Schwartz,
R. S. 1998. "Neointimal Response Following Rotational Atherectomy
Compared to Balloon Angioplasty in a Porcine Model of Coronary
In-stent Restenosis," Catheterization and Cardiovascular Diagnosis
45(3):332-336). Some methods in actual practice impose greater
trauma and risk of complications than do the means for
accomplishing an angioplasty and stenting described herein.
[0898] Those documented in the literature include percutaneous
intentional extraluminal recanalization (revascularization,
subintimal angioplasty) (see Scott et al. 2007, Ko et al. 2007, Cho
et al. 2006, Mishkel et al. 2005 referred to under the section
above entitled Risk of Abrupt Closure) and vessel size-adapted
angioplasty pursuant to a concept of `therapeutic dissections,`
addressed below in the section below entitled Basic Strengths and
Weaknesses of Prior Art Stenting in Vascular, Tracheobronchial,
Gastrointestinal, and Urological Interventions, among others. Other
cabled cabled devices that can be included in a combination-form
barrel-assembly for removing calcified plaque include lasers and
ultrasonic probes.
[0899] The inability of a laser catheter to remove more than
moderately calcified plaque by cavitation, thermal breakdown, and
vaporization (see, for example, Vorwerk, D., Zolotas, G.,
Kohnemann, R., Hessel, S., Adam, G., and Gunther, R. W. 1990.
"Laserangioplastie und Abtragung kalzifizierter Plaques, Eine
In-vitro-Studie" [Laser Angioplasty and the Removal of Calcified
Plaques. An in Vitro Study], in German with abstract in English at
Pubmed, RoFo.: Fortschritte auf dem Gebiete der Rontgenstrahlen und
der Nuklearmedizin (RoFo [Rontgenstrahlen Fortschritte]: Advances
in the Field of X-rays and Nuclear Medicine) 152(6):693-697) and of
a 2.1 micron holmium laser to do so at fluences per pulse of less
than 205 Joules per square centimeter (see Vorwerk, D., Zolotas,
G., Hessel, S., Adam, G., Wondrazek, F., and Gunther, R. W. 1991.
"In Vitro Ablation of Normal and Diseased Vascular Tissue by a
Fiber-transmitted Holmium Laser," Investigative Radiology
26(7):660-664) has been contradicted by others (see Ben-Dor, I.,
Maluenda, G., Pichard, A. D., Satler, L. F., Gallino, R., Lindsay,
J., and Waksman, R. 2011. "The Use of Excimer Laser for Complex
Coronary Artery Lesions," Cardiovascular Revascularization Medicine
12(1):69.e1-e8; Bilodeau, L., Fretz, E. B., Taeymans, Y., Koolen,
J., Taylor K., and Hilton, D. J. 2004. "Novel Use of a High-energy
Excimer Laser Catheter for Calcified and Complex Coronary Artery
Lesions," Catheterization and Cardiovascular Interventions 62(2):
155-161).
[0900] Another cabled device that can be incorporated into a
combination-form barrel-assembly is an ultrasonic catheter,
likewise claimed effective at removing calcified plaque (Siegel, R.
J. 1996. Ultrasound Angioplasty, Boston, Mass.: Kluwer Academic
Publishers/Springer; Siegel, R. J., Gaines, P., Crew, J. R., and
Cumberland, D. C. 1993. "Clinical Trial of Percutaneous Peripheral
Ultrasound Angioplasty," Journal of the American College of
Cardiology 22(2):480-488; Chikada, M. 2004. "An Experimental Study
of Surgical Ultrasonic Angioplasty: Its Effect on Atherosclerosis
and Normal Arteries," Annals of Thoracic Surgery 77(1):243-246;
Gavin, G. P., McGuinness, G. B., Dolan, F., and Hashmi, M. S. J.
2005. "Development and Performance Characteristics of an Ultrasound
Angioplasty Device," Dublin Institute of Technology School of
Manufacturing and Design Engineering, Bioengineering Conference
Papers, available at http://arrow.ditie/engschmanconn/2; Wylie, M.,
McGuinness, G. B., and Gavin, G. P. 2009. "Therapeutic Ultrasound
Angioplasty: The Risk of Arterial Perforation. An in Vitro Study,"
Dublin Institute of Technology School of Manufacturing and Design
Engineering, Bioengineering Conference Papers, available at
http://arrow.ditie/engschmanconn/7).
[0901] Applied to a chronic total occlusion of a coronary artery,
revascularization by such means is more likely to result in
restenosis concurrent with atrophy of the collateral circulation
that developed to adapt to the occlusion, with the consequence
catastrophic (see, for example, Pohl, T., Hochstrasser, P.,
Billinger, M., Fleisch, M., Meier, B., and Seiler, C. 2001.
"Influence on Collateral Flow of Recanalising Chronic Total
Coronary Occlusions: A Case-control Study," Heart 86(4):438-443).
Abrupt closure with vasospasm, or vasoconstriction, as the result
of balloon overstretching or followng placement of a drug-eluting
stent is addressed above in the section entitled Risk of Abrupt
Closure with Thrombus and Vasospasm. Passage of severely stenosed
and tortuous stretches by a barrel-assembly muzzle-head of suitable
diameter is by slippage (slip-through, slide-through), the nose
convex or spheroconical (torpedo or bullet-nosed) and
lubricious.
[0902] The risk of abrupt closure with or without concomitant
vasospasm using the apparatus described herein is addressed in the
section above of like title. If not creating a flap that results in
an abrupt closure, balloon angioplasty with an oversized balloon or
overinflation can produce stretching injury, dissections, and
thrombus, and with underinflation too narrow a lumen, in either
contingency, leading to subacute closure (Cheneau, E., Mintz, G.
S., Leborgne, L., Kotani, J., Satler, L. F., Ajani, A. E.,
Weissman, N. J., Waksman, R., and Pichard, A. D. 2004. "Intraductal
Ultrasound Predictors of Subacute Vessel Closure After Balloon
Angioplasty or Atherectomy," Journal of Invasive Cardiology
16(10):572-574; Cheneau, E., Leborgne, L., Mintz, G. S., Kotani,
J., Pichard, A. D., Satler, L. F., Canos, D., Castagna, M.,
Weissman, N. J., and Waksman, R. 2003. "Predictors of Subacute
Stent Thrombosis: Results of a Systematic Intraductal Ultrasound
Study," Circulation 108(1):43-47).
[0903] Removal of tissue protrusive into the lumen is primarily
through the application of heat directed, or of cutting or abrasive
tools projected, radially outward from the muzzle-head or radial
projection catheter. Cold is obtained by attaching a source of
CO.sub.2 or a chilled liquid to the barrel-assembly. Eliminating a
guidewire eliminates the potential for guidewire breakage, which
can result in the intra-arterial loss of a fragment and gouging or
rupture of the vessel wall. Such incidents and the complications to
which these give rise are rare but continue to be reported in the
literature (references provided below under the section entitled
Strengths and Weaknesses of Conventional Interventions). Additional
complications from guidewires are addressed below in this section.
Using the apparatus to be described, plaque is removed rather than
crushed, which is injurious when a balloon is overinflated.
[0904] Atherectomy performed by any of the foreoing means with
medical follow-up actually removes the plaque or other occlusive
matter, and therefore would appear to have the potential to reduce
if not eliminate the need for stenting (see Sharma, S. K., Kini,
A., Mehran, R., Lansky, A., Kobayashi, Y., and Marmur, J. D. 2004.
"Randomized Trial of Rotational Atherectomy versus Balloon
Angioplasty for Diffuse In-stent Restenosis (ROSTER)," American
Heart Journal 147(1):16-22; Shafique, S., Nachreiner, R. D.,
Murphy, M. P., Cikrit, D. F., Sawchuk, A. P., and Dalsing, M. C.
2007. "Recanalization of Infrainguinal Vessels: Silverhawk, Laser,
and the Remote Superficial Femoral Artery Endarterectomy," Seminars
in Vascular Surgery 20(1):29-36).
[0905] In practice, however, no means for reinstating patency
completely avoids the risk of restenosis. Endoluminal stenting may
serve balloon angioplasty by covering over any dissections, to
include loose flaps that would induce an abrupt closure, that may
have resulted from overinflation and by retaining or `tacking up`
debris compressed against the lumen wall, thus preventing debris
greater in diameter than 5 micrometers, which is too large to pass
through capillaries, from passing downstream. By contrast,
extraluminal stenting as described herein does not achieve patency
by endoluminal scaffolding and therefore does not simply force
debris up against the lumen wall merely to counteract balloon
damage and its sequelae of hyperplasia, shrinkage, and spasm.
[0906] Combined nonatherectomizing angioplasty and endoluminal
stenting usually results in the inward protrusion through the stent
struts of the unremoved atheroma. The advent of absorbable
endoluminal stents may discourage this practice, since any residual
diseased tissue that had been compressed could be released to
embolize downstream as the stent is absorbed. Since in some
patients, even with medication, the sites, such as bifurcations and
oscula, but not the interval preceding the development of lesions
can be predicted, absorbable stents cannot be used preventively. By
contrast, the extraluminal stents described herein can be placed at
any time, retain patenting effectiveness indefinitely, and can
therefore be prepositioned to preventive effect. Drugs such as
statins alone can reduce the inflammation associated with arterial
disease and detain the emergence but not dissolve atheromas.
[0907] Omitting a preliminary angioplasty may interfere with
absorption of the stent into the luminal wall. The minimally
invasive use without an antecedent angioplasty of an
everolimus-eluting absorbable stent, for example, therefore
recommends either an angioplasty prior to insertion or that the
stent also be irradiated. The more invasive implantation of
irradiating seeds to suppress restenosis before the stent is
absorbed is unrealistic, a suitable means for introducing such
necessitating the use of a stay insertion tool or barrel-assembly
as described herein. The barrel-assemblies described herein include
ablative capability in a type device that can be used with single
entry and withdrawal for that limited purpose or to implant any
luminal wall with medication and/or ferromagnetic material as well
at any moment in any order. Such supplants the need for a separate
and inherently inferior form of angioplasty and the use of an
inherently inferior endoluminal stent.
[0908] Moreover, by changing the magazine clip or removing the
barrel-assembly from one airgun and inserting it into another, the
type miniball implants as medicinal, consisting of or containing
binding agents, tissue hardeners, tumefacients, irradiating seeds,
or any combination thereof can be changed in an instant. Similarly,
stays can be loaded into the insertion tool in any sequence or a
tool containing one type stay can be withdrawn and another
introduced. Not intended to trap smashed atheromas up against lumen
walls in order to secondarily compensate for a deficiency of
balloon angioplasty, extraluminal stenting is paired primarily with
thermoablation and vibratory cutting tools, which can be used in
combination and do not apply outward radial force against the wall
of the lumen merely to crush, rather than to actually remove,
plaque or obstructive tissue (see, for example, Heintzen, M. P.,
Aktug, O., and Michel, C. J. 2002. "Debulking Prior to Stenting--A
Worthwhile Effort?," Zeitschrift fur Kardiologie 91 Suppl
3:72-76).
[0909] The actual removal of diseased tissue such as atheromata or
plaque (atheroablation), as opposed to its mere crushing and
displacement through balloon angioplasty preferable, and
endoluminal stenting being a multirisk-laden underpinning or
`crutch` for balloon angioplasty as an inferior method for clearing
the lumen, the pairing of a photoablative laser with extraluminal
stenting comprehends major improvements of both, making the
accommodation by the barrel-assembly of a laser beneficial. Since
thermoplasty and oscillatory ablative capabilities are built into
ablation and ablation and angioplasty-capable barrel-assemblies,
atherectomy and implantation of the intraductal component of the
extraluminal stent is accomplished with single entry. Cutting tools
if any retracted, the turret-motor drive can be programmed for
oscillation to assist passage through tortuous stretches, and
trackability can be further expedited through the release of a
lubricant from the muzzle-head.
[0910] The release of fluid substances into the lumen wall using
radial projection units is addressed below in the section entitled
Radial Projection Unit Tool-inserts and in sections pertaining to
injection tool-inserts. Release into the lumen is through
electrically, electrochemically, or fluidically operated
tool-insert ejection syringes or a barrel-tube. The barrel-assembly
provides multiple means for removing plaque or other diseased
tissue and/or adherent material in other type ductus. Through-bore
or combination-form barrel-assemblies and radial projection
catheters can incorporate a laser for photoablation or a rotational
cutting tool for atherectomy. For use as a separate device, an
ablation or ablation and angioplasty-capable barrel-assembly
demands free and independent mobility.
[0911] To this end, the power and control housing can be slid along
the barrel-catheter into position just short of the length of the
barrel-assembly that will be inserted into the barrel of the
airgun. A control panel for ablative and angioplastic functions is
mounted to the side of the housing. When mated to an ensheathing,
or ensleeving, radial projection catheter thereby to constitute a
duplex (composite, bipartite) barrel-assembly, the power and
control housings of each can be slid along the shafts of both in
adjacent relation. These ballistic implantation-preparatory or
end-purpose ablation or angioplasty controls include those for
heating the turret-motor stator and for heating either or both of
the recovery electromagnet windings, deploying the radial
projection unit tool-inserts, rotating the turret-motor, and thus
directing (rotating) an eccentric (slot or slit shaped)
turret-motor heat-window and/or radial projection unit
tool-inserts, for example.
[0912] Encouraging preemptive thermoplasty by nose and other
heat-windows in the muzzle-head is the finding that an acute event
most often results from sudden thrombogenic occlusion attendant
upon the release of necrotic core material following the rupture of
a fatty atheromatous plaque or a thin fibrous capped atheroma, or
fibroatheroma, exposed to low density lipoprotein laden blood
(Virmani, R., Burke, A. P., Farb, A., and Kolodgie, F. D. 2006.
"Pathology of the Vulnerable Plaque," Journal of the American
College of Cardiology 47(8 Supplement):C13-18; Virmani, R., Burke,
A. P., Kolodgie, F. D., and Farb, A. 2002. "Vulnerable Plaque: The
Pathology of Unstable Coronary Lesions," Journal of Interventional
Cardiology 15(6):439-446; Burke, Farb, A., Malcom, G. T., Liang, Y.
H., Smialek, J., and Virmani, R. 1997. "Coronary Risk Factors and
Plaque Morphology in Men with Coronary Disease Who Died Suddenly,"
New England Journal of Medicine 336(18):1276-1282Farb, A., Burke,
A. P., Tang, A. L., Liang, T. Y., Mannan, P , Smialek, J., and
Virmani, R. 1996. "Coronary Plaque Erosion Without Rupture into a
Lipid Core. A Frequent Cause of Coronary Thrombosis in Sudden
Coronary Death," Circulation 93(7):1354-1363;) or the rupture of
vulnerable plaque where the reduction in flow has not yet been
compensated for by the development of collateral circulation; by
contrast, a gradual cutoff of flow through the lumen due to a
plaque that has gradually come to protrude into the lumen to a
greater extent is so compensated. For this reason, a vessel with
chronic total occlusion can be asymptomatic and one slightly
protrusive can cause death. An angioplasty that discourages the
development of collateral circulation can be counterproductive.
[0913] Smashing plaque that is not vulnerable but merely protrudes
into the lumen can actually cause an infarction, and this
consequence is more likely when the plaque is indeed vulnerable
(Waksman, R. Serruys, P. W., and Schaar, J. 2007. Handbook of the
Vulnerable Plaque, London, England: Informa Healthcare; Waxman, S.,
Ishibashi, F., and Muller, J. E. 2006. "Detection and Treatment of
Vulnerable Plaques and Vulnerable Patients: Novel Approaches to
Prevention of Coronary Events," Circulation 114(22):2390-2411;
Naghavi, M.; Libby, P; Falk, and 55 others 2003. "From Vulnerable
Plaque to Vulnerable Patient: A Call for New Definitions and Risk
Assessment Strategies: Part I," Circulation 108(14):1664-1672;
Libby, P. and Aikawa, M. 2002. "Stabilization of Atherosclerotic
Plaques: New Mechanisms and Clinical Targets," Nature Medicine
8(11)1257-1262, erratum 9(1):146; Moreno, P. R. 2001.
"Pathophysiology of Plaque Disruption and Thrombosis in Acute
Ischemic Syndromes," Journal of Stroke and Cerebrovascular Disease
10(2 Part 2):2-9; Muller, J. E. Abela, G. S. Nesto, R. W. and
Tofler, G. H. 1994. "Triggers, Acute Risk Factors and Vulnerable
Plaques: The Lexicon of a New Frontier," Journal of the American
College of Cardiology 23(3):809-813; Ley, O. and Kim, T. 2007.
"Calculation of Arterial Wall Temperature in Atherosclerotic
Arteries: Effect of Pulsatile Flow, Arterial Geometry, and Plaque
Structure," Biomedical Engineering Online 6:8; ten Have, A. G.,
Gijsen, F. J., Wentzel, J. J., Slager, C. J., and van der Steen, A.
F. 2004. "Temperature Distribution in Atherosclerotic Coronary
Arteries: Influence of Plaque Geometry and Flow (a Numerical
Study)," Physics in Medicine and Biology 49(19):4447-4462; Shah, P.
K. 2002. "Pathophysiology of Coronary Thrombosis: Role of Plaque
Rupture and Plaque Erosion," Progress in Cardiovascular Diseases
44(5):357-368).
[0914] When collateral circulation is insufficient, reperfusion or
recanalization to the Thrombolysis in Myocardial Infarction
study-defined Grade III (TIMI III, normal) flow is known to produce
a more favorable prognosis the more promptly it is accomplished.
However, when collateral circulation is sufficient, even coronary
total occlusion (see, for example, Waksman, R. (ed.) 2009. Chronic
Total Occlusions, Hoboken, N.J.: Wiley-Blackwell) may be disserved
by angioplasty, which given a heavy burden of plaque, can reduce if
not eliminate the collateral circulation by involution (Pohl, T.,
Hochstrasser, P., Billinger, M., Fleisch, M., Meier, B., and
Seiler, C. 2001. "Influence on Collateral Flow of Recanalising
Chronic Total Coronary Occlusions: A Case-control Study," Heart
86(4):438-443) or embolization (Meier, B. 1989/2005. "Angioplasty
of Total Occlusions: Chronic Total Coronary Occlusion Angioplasty,"
Catheterization and Cardiovascular Diagnosis 17(4):212-217; Kahn,
J. K. 1995/2005. "Collateral Injury by Total Occlusion Angioplasty:
Biting the Hand that Feeds Us," Catheterization and Cardiovascular
Diagnosis 34 (3): 65-66; Ha, J. W., Cho, S. Y., Chung, N., Choi, D.
H., Choi, B. J., Jang, Y., Shim, W. H., and Kim, S. S. 2002. "Fate
of Collateral Circulation After Successful Coronary Angioplasty of
Total Occlusion Assessed by Coronary Angiography and Myocardial
Contrast Echocardiography," Journal of the American Society of
Echocardiography 15(5):389-395; Waser, M., Kaufmann, U., and Meier,
B. 1999. "Mechanism of Myocardial Infarction in a Case with Acute
Reocclusion of a Recanalized Chronic Total Occlusion: A Case
Report," Journal of Interventional Cardiology 12 (2), 137-140.
Stone, G. W., Kandzari, D. E., Mehran, R., Colombo, A., and 23
Other Authors 2005. "Percutaneous Recanalization of Chronically
Occluded Coronary Arteries: A Consensus Document, Part I,"
Circulation 112(15):2364-2372).
[0915] Thus, the need for stenting is often the direct result of
and used to cover over inadequacies of balloon angioplasty, which
rather than to remove, only crushes plaque and can subject the
lumen wall to stretching injury and dissections that can resit in
an abrupt closure (see, for example, cases 3-5 in Farb, A.,
Lindsay, J. Jr., and Virmani, R. 1999. "Pathology of Bailout
Coronary Stenting in Human Beings," American Heart Journal 137(4
Part 1):621-631 and 579-581; Marti, V., Montiel, J., Aymat, R. M.,
Garcia, J., Guiteras, P., Kozak, F., and Auge, J. M. 1999.
"Expanding Subintimal Coronary Dissection Under a Stent-covered
Arterial Segment: Serial Intraductal Ultrasound Observations,"
Catheterization and Cardiovascular Interventions 48(3):308-311
Alfonso, F., Hernandez, R., Goicolea, J., Segovia, J.,
Perez-Vizcayno, M. J., Banuelos, C., Silva, J. C., Zarco, P., and
Macaya, C. 1994. "Coronary Stenting for Acute Coronary Dissection
after Coronary Angioplasty: Implications of Residual Dissection,"
Journal of the American College of Cardiology 24(4):989-995) that
stimulate constrictive remodeling, or arterial shrinkage as " . . .
the predominant factor responsible for luminal narrowing after
balloon angioplasty" and the stimulant for intimal hyperplasia
(Pasterkamp, G., Mali, W. P., and Borst, C. 1998. "Application of
Intraductal Ultrasound in Remodelling Studies," Seminars in
Interventional Cardiology 2(1):11-18); see also Smits, P. C., Bos,
L. Quarles van Ufford, M. A., Eefting, F. D., Pasterkamp, G., and
Borsta, C. 1998. "Shrinkage of Human Coronary Arteries is an
Important Determinant of de Novo Atherosclerotic Luminal Stenosis:
An in Vivo Intraductal Ultrasound Study," Heart 79(2):143-147;
Narins, C. R., Holmes, D. R. Jr., and Topol, E. J. 1998. "A Call
for Provisional Stenting: The Balloon is Back!," Circulation
97(13):1298-1305; Teo, K. K. 1998. "Clinical Review: Recent
Advances, Cardiology," British Medical Journal
316(7135):911-915).
[0916] Unlike balloon angioplasty, which crushes vulnerable or
unstable plaque, allowing it to release embolizing debris,
ablation, such as through thermoablation, destroys the debris,
reducing the risk of inducing an ischemic event. Occlusive events
range from the stunned myocardium (postischemic contractile
dysfunction, or if stunned repeatedly, prolonged postischemic
ventricular dysfunction of viable myocardium) (see, for example,
Braunwald, E. and Kloner, R. A. 1982. "The Stunned Myocardium:
Prolonged, Postischemic Ventricular Dysfunction," Circulation
66(6):1146-1149; Bolli, R. 1992. "Myocardial `Stunning` in Man,"
Circulation 86(6):1671-1691) to a cardiac arrest or a myocardial
infarction; from a temporary ischemic attack to a cerebral
infarction (stroke); or to an infarction elsewhere in the body.
[0917] Some endorse `therapeutic dissections` whereby " . . .
substantial dissections following PTCA [percutaneous transluminal
coronary angioplasty using `vessel size-adapted PTCA;` that is,
dilation using a large balloon based upon measurements gained by
intraductal ultrasound], which do not diminish antegrade blood
flow, do not lead to an increase in acute or long-term events,"
(Schroeder, S., Baumbach, A., Mahrholdt, H., Haase, K. K.,
Oberhoff, M., Herdeg, C., Athanasiadis, A., and Karsch, K. R. 2000.
"The Impact of Untreated Coronary Dissections on Acute and
Long-term Outcome after Intraductal Ultrasound guided PTCA,"
European Heart Journal 21(2):137-145 and 21(2):92-94; Schroeder,
S., Baumbach, A., Haase, K. K., Oberhoff, M., Marholdt, H., Herdeg,
C., Athanasiadis, A., and Karsch, K. R. 1999. "Reduction of
Restenosis by Vessel Size Adapted Percutaneous Transluminal
Coronary Angioplasty Using Intraductal Ultrasound," American
Journal of Cardiology 83(6):875-879). However, dissection resulting
in abrupt closure can occur even with a smaller balloon (references
above in the section entitled Risk of Abrupt Closure), as can a
ductus-intramural or intraparietal hematoma (see Werner, G. S.,
Figulla, H. R., Grosse, W., and Kreuzer, H. 1995. "Extensive
Intramural Hematoma as the Cause of Failed Coronary Angioplasty:
Diagnosis by Intraductal Ultrasound and Treatment by Stent
Implantation," Catheterization and Cardiovascular Diagnosis 36(2):
173-178).
[0918] More aggressive angioplasty can also produce a
pseudoaneurysm (see, for example, Lell, E., Wehr, G., and Sechtem,
U. 1999. "Delayed Development of a Coronary Artery Pseudoaneurysm
after Angioplasty," Catheterization and Cardiovascular
Interventions 47(2):186-190), followup stenting notwithstanding
(see, for example, Cafri, C., Gilutz, H., Kobal, S., Esanu, G.,
Weinstein, J. M., Abu-Ful, A., and Ilia, R. 2002. "Rapid Evolution
from Coronary Dissection to Pseudoaneurysm after Stent
Implantation: A Glimpse at the Pathogenesis Using Intraductal
Ultrasound," Journal of Invasive Cardiology 14(5):286-289; Kitzis,
I., Kornowski, R., and Miller, H. I. 1997. "Delayed Development of
a Pseudoaneurysm in the Left Circumflex Artery Following
Angioplasty and Stent Placement, Treated with Intraductal
Ultrasound-guided Stenting," Catheterization and Cardiovascular
Diagnosis 42(1):51-53), aneurysm (see, for example, Berkalp, B.,
Kervancioglu, C., and Oral, D. 1999. "Coronary Artery Aneurysm
Formation after Balloon Angioplasty and Stent Implantation,"
International Journal of Cardiology 69(1):65-70), and an aneurysm
that ruptured (see, for example, Chou, T. M., Amidon, T. M., and
Ports, T. A. 1993. "Contained Rupture Following Percutaneous
Transluminal Coronary Angioplasty: Long-term Outcome,"
Catheterization and Cardiovascular Diagnosis 28(2):152-154). An
intrinsic defect of some balloons remains focal expansion, or
disproportionate expansion over the surface of the balloon so that
different areas of the vessel wall are subjected to greater outward
radial force (see, for example, Kokish, A. 2002. "Balloon with the
Variable Radial Force Distribution," U.S. Pat. No. 6,391,002).
[0919] The outer shell of the muzzle-head is made of or coated with
a low friction fluoropolymer and has a bullet or torpedo-configured
nose to move through the lumen without catching (seizing, clinging)
or pulling. If necessary, the muzzle-head is wetted with a
lubricant during use with an interventional lubricant by means
within it, such as those specified in the section below entitled
Sectional, or Chain-stents, Segmented and Articulated, for example.
Furthermore, the vibratory or oscillatory mode discussed under the
sections below entitled Turret-motor Operational Modes among others
is also available to assist in negotiating tight curves otherwise
difficult to traverse. Thus, in contrast to the expansion of a
balloon to apply outward force against the lumen wall, the highly
lubricious (slippery, slick) and nonexpanding muzzle-head does not
cause stretching injury, even when negotiating sharp curves and
tortuous stretches.
[0920] While the superiority of atherectomy over balloon
angioplasty has been argued against (see, for example, Douglas, J.
S. Jr. and King, S. B. III 2008. "Percutaneous Cornonary
Intervention," in Fuster, V., O'Rourke, R. A., Walsh, R.,
Poole-Wilson, P., (eds.), Hurst's The Heart, New York, N.Y.:
McGraw-Hill; Bittl, J. A., Chew, D. P., Topol, E. J., Kong, D. F.,
and Califf, R. M. 2004. "Meta-analysis of Randomized Trials of
Percutaneous Transluminal Coronary Angioplasty versus Atherectomy,
Cutting Balloon Atherotomy, or Laser Angioplasty," Journal of the
American College of Cardiology 43(6):936-942; Mauri, L., Reisman,
M., Buchbinder, M., Popma, J. J., Sharma, S. K., Cutlip, D. E., Ho,
K. K., Prpic, R., Zimetbaum, P. J., and Kuntz, R. E. 2003.
"Comparison of Rotational Atherectomy with Conventional Balloon
Angioplasty in the Prevention of Restenosis of Small Coronary
Arteries: Results of the Dilatation vs Ablation Revascularization
Trial Targeting Restenosis (DART)," American Heart Journal
145(5):847-854), this may have been due to inadequacy in the volume
of tissue removed (Haager, P. K., Schiele, F., Buettner, H. J.,
Garcia, E., and ten other authors 2003. "Insufficient Tissue
Ablation by Rotational Atherectomy Leads to Worse Long-term Results
in Comparison with Balloon Angioplasty Alone for the Treatment of
Diffuse In-stent Restenosis: Insights from the Intraductal
Ultrasound Substudy of the ARTIST Randomized Multicenter Trial,"
Catheterization and Cardiovascular Interventions 60(1):25-31;
Safian, R. D., Freed, M., Lichtenberg, A., May, M. A., Juran, N.,
Grines, C. L., and O'Neill, W. W. 1993. "Are Residual Stenoses
after Excimer Laser Angioplasty and Coronary Atherectomy Due to
Inefficient or Small Devices? Comparison with Balloon Angioplasty,"
Journal of the American College of Cardiology 22(6):
1628-1634).
[0921] However, if trauma is the cause of restenosis (see, for
example, Ahn, S. S. and Ro, K. M. 2004. "Peripheral Atherectomy,"
in Hobson, R. W. II, Wilson, S. E. and Veith, F. J., Vascular
Surgery Principles and Practice, New York, N.Y.: Marcel Dekker
Division, Taylor and Francis, pages 359-360), then the medication
and/or radiation used to suppress restenosis warrant further study.
While at least for use in the carotid arteries reservations appear
in the literature (see, for example, Vijayvergiya, R., Otaal, P.
S., Bagga, S., and Modi, M. 2010. "Symptomatic Carotid Vasospasm
Caused by a Distal-Protection Device during Stent Angioplasty of
the Right Internal Carotid Artery," Texas Heart Institute Journal
37(2):226-229; Schirmer, C. M., Hoit, D. A., and Malek, A. M. 2008.
"Iatrogenic Vasospasm in Carotid Artery Stent Angioplasty with
Distal Protection Devices," Neurosurgical Focus 24(2):E12; Iyer,
V., de Donato, G., Deloose, K., Peeters, P., Castriota, F.,
Cremonesi, A., Setacci, C., and Bosiers, M. 2007. "The Type of
Embolic Protection Does Not Influence the Outcome in Carotid Artery
Stenting.," Journal of Vascular Surgery 46(2):251-256), another
problem with directional atherectomy, embolization by debris, can
be ameliorated through the use of a distal embolic protective
filter (see, for example, section 4d(2) entitled Ductus Wall
Tumefacients and Shammas, N. W., Deppel, E. J., Coiner, D.,
Shammas, G. A., Jerin, M., and Kumar, A. 2008. "Preventing Lower
Extremity Distal Embolization Using Embolic Filter Protection:
Results of the PROTECT Registry," Journal of Endovascular Therapy
15(3):270-282).
[0922] Combination-form barrel-assemblies and radial projection
catheters, addressed below in sections of like respective title,
can accommodate a rotational atherectomy cutting head. The problem
is less pronounced, but a filter would likely prove of benefit with
a rotatory burr as well (see, for example, Friedman, H. Z.,
Elliott, M. A., Gottlieb, G. J., and O'neill, W. W. 1989.
"Mechanical Rotary Atherectomy: The Effects of Microparticle
Embolization on Myocardial Blood Flow and Function," Journal of
Interventional Cardiology 2(2):77-83). At least immediately
following the procedure, the actual excision of plaque by
atherectomy results in a larger luminal cross-sectional area than
does balloon angioplasty (Ikeno, F., Braden, G. A., Kaneda, H.,
Hongo, Y., Hinohara, T., Yeung, A. C., Simpson, J. B., and
Kandzari, D. E. 2007. "Mechanism of Luminal Gain with Plaque
Excision in Atherosclerotic Coronary and Peripheral Arteries:
Assessment by Histology and Intraductal Ultrasound," Journal of
Interventional Cardiology 20(2):107-113), and the gain appears to
be attributable to the removal of plaque rather than its
compression at the cost of luminal stretching (Marsico, F., Kubica,
J., De Servi, S., Angoli, L., Bramucci, E., Costante, A. M., and
Specchia, G. 1995. "Influence of Plaque Morphology on the Mechanism
of Luminal Enlargement after Directional Coronary Atherectomy and
Balloon Angioplasty," British Heart Journal 74(2): 134-139).
[0923] In concept, atherectomy should eventually prove inherently
superior in terms of long-term results as well (see, for example,
Garcia, L. A. and Lyden, S. P. 2009. "Atherectomy for Infrainguinal
Peripheral Artery Disease," Journal of Endovascular Therapy 16(2
Supplement 2):II105-II115; Repetto, A., Ferlini, M., Ferrario, M.,
Angoli, L., and Bramucci, E. 2005. "Directional Coronary
Atherectomy in 2005," Italian Heart Journal 6(6):494-497).
Directional atherectomy is also able to deal with openings (ostia)
and bifurcations that a balloon cannot articulate (Favero, L.,
Simpson, J. B., and Reimers, B. 2004. "Treatment of an Ostial and a
Bifurcation Lesion with a New Directional Atherectomy Device,"
Heart 90(8):e46; Ho, G. H. and Moll, F. L. 1999. "Disobliteration
Techniques," in White, R. A. and Fogarty, T. J. (eds.), Peripheral
Endovascular Interventions, New York, N.Y.: Springer).
[0924] Almost always incorporated into the muzzle-head will also be
two or more radial projection units containing side-looking
(side-sweeping, stiff brush, or ecouvillonage) type tool-inserts,
as addressed below in the section entitled Radial Projection Units.
Side-sweeping or brush type tool-inserts have variously configured
tips on shafts of variable length similar to bristles or blades.
Brush and swab (ecouvillon) type tool-inserts are limited to the
removal of material adherent to or beneath the intima softer than
calcified plaque or oxalate salt, for example. Any kind of radial
projection unit tool-insert can be deployed during manual or linear
positioning stage mediated advancement or withdrawal of the
barrel-assembly. An angioplasty-capable barrel-assembly, as
addressed below in the section of like title, can incorporate a
run-ahead protective embolic filter.
[0925] Then, to preclude downstream embolization by debris
generated by the tool-inserts, the same switch used to deploy and
retract the radial projection unit tool-inserts can be made to
control a run-ahead embolic trap-filter that is stowed (stored)
within a sheath or silo in the nose of the muzzle-head when not
deployed. Addressed below in the section entitled Ablation or
Ablation and Angioplasty-capable Barrel-assembly Onboard Control
Panel, these switches are included in the barrel-assembly ablation
or angioplasty control panel. Side-sweeping tool-inserts or
side-sweepers, addressed below under the section entitled Radial
Projection Unit Tool-inserts, can be configured as cytological
sample collection brushes, for example. To avoid the need to
withdraw the barrel-assembly in order to recover the tissue sample,
the brushed surface is aspirated.
[0926] To do this, the closest barrel-tube or, when the sample
would not be drawn out through the barrel-tube under a slight
vacuum, then a barrel-tube insert lining, or service-catheter, is
passed over the brushed surface to aspirate additional tissue for
analysis. In order of increased control over the vacuum force used,
this is done by bulb or syringe pipetting, a bulb expelled of air,
or a suction (aspiration) pump. Aspiration is also possible through
fluidically operated, or piped, radial projection units, as
addressed in the section of like title. Depending primarily upon
tissue hardness, the radial projection units positioned about the
muzzle-head can be engaged with tool-inserts having bristle
projections of different length and tip shape or razor edges, so
that one type, for example, can be used to obtain a tissue sample
for brush or slide cytology prior to resuming the procedure, as
others are used to remove plaque.
[0927] Using fluidically operated tool-insert or barrel-tube
aspiration, endoluminal lavage for washing and/or, diagnosis, or
antisepsis can be performed midprocedurally without withdrawal
before or after this action, as addressed below in the section
entitled Service-catheters and Use of the Barrel-assembly as a
Guide-catheter. When stenting is to follow angioplasty or
atherectomy without withdrawal, a barrel-assembly is used;
otherwise, a radial projection catheter can be used. A benefit in
the use of an ablation or ablation and angioplasty-capable
barrel-assembly, and a combination-form barrel-assembly in
particular, is that it contains multiple tools for dealing with
differently diseased tissues or plaque.
[0928] The operator can therefore proceed from one segment to the
next with the means for dealing with differing plaque already
available without the need for withdrawal and reentry. While a
muzzle-head with radial projection unit brush and razor edge
tool-inserts can accomplish the removal of soft plaque, the
combination-form barrel-assemblies as described below in the
section entitled Through-bore, or Combination-form,
Barrel-assemblies: Barrel-assemblies which Accommodate or
Incorporate Means for Ablation, Thrombectomy, Atherectomy,
Atherotomy, and/or Endoscopy, can accommodate a laser catheter,
directional, or rotational atherectomy burr.
[0929] These allow the prominences when hardened, confluent, and
protruding into the lumen to be removed, while radial projection
unit tool-inserts of a bristle hardness or tip type selected for
the specific plaque are used to reduce the plaque that tends to
include discrete particulate calcifications beneath the lumen
surface where it is more amenable to being swept and aspirated
away. As most arteries are too narrow to use a combination form
barrel-assembly that incorporates a laser; the use of a laser often
necessitate an initial entry with a conventional (independent)
laser prior to insertion of the barrel-assembly. Laser atherectomy
is able to remove moderately calcified lesions by actually
cavitating, disintegrtating, and vaporizing the occlusive
material.
[0930] Also in an artery too small to pass a combination-form
barrel-assembly, when plaque is so calcified that a laser cannot
remove it, the preceding use of a rotational burr is indicated.
However, when a combination-form will pass, a laser can be
withdrawn and replaced by a rotational burr without withdrawing the
barrel-assembly. Calcification of plaque tending to increase
adaxially, or the more toward the long axis of the lumen, when the
degree of calcification does not disallow, a laser catheter
incorporated into the barrel-assembly as described in the section
below on combination-forms is used in a forward direction, or
distad, without deployment of the side-brushes and trap-filter.
When the direction is reversed to proximad, side-brushes, embolic
filter, and optionally, the turret-motor or miniball recovery and
extraction tractive electromagnets for thermal angioplasty, are
actuated.
[0931] Otherwise unused barrel-tubes or fluidic tool-inserts can be
used to aspirate. Accomplished thus, the forward pass addresses
plaque more adaxial (central) in the lumen, while the return pass
addresses that more abaxial (peripheral). When the plaque is stony,
a rotational burr is used for the first or distad pass. Since the
embolic filter cannot be deployed ahead of a laser, the concurrent
use of side-brushes with the laser requires that the laser destroy
any debris liberated by the side-brushes. Thus, normally whenever
the laser and side-brushes are actuated together, the simultaneous
deployment of the trap-filter with the side-brushes is
electronically overriden. Otherwise, the trap-filter is separately
actuable for deployment as desired.
[0932] Mineralization at the cap has been hypothesized by some to
make plaque less and by other more vulnerable (see, for example,
Li, Z. Y., Howarth, S., Tang, T., Graves, M., U-King-Im, J., and
Gillard, J. H. 2007. "Does Calcium Deposition Play a Role in the
Stability of Atheroma? Location May be the Key," Cerebrovascular
Disease 24(5):452-459), and by others, less vulnerable (see, for
example, Miralles, M., Merino, J., Busto, M., Perich, X., Barranco,
C., and Vidal-Barraquer, F. 2006. "Quantification and
Characterization of Carotid Calcium with Multi-detector
CT-Angiography," European Journal of Vascular and Endovascular
Surgery 32(5):561-567). Different imaging methods allow the
distribution of calcium to be detected (see, for example,
Moselewski, F., O'Donnell, C. J., Achenbach, S., Ferencik, M.,
Massaro, J., Nguyen, A., Cury, R. C., Abbara, S., Jang, I. K.,
Brady, T. J., and Hoffmann, U. 2005. "Calcium Concentration of
Individual Coronary Calcified Plaques as Measured by Multidetector
Row Computed Tomography," Circulation 111(24):3236-3241; Wexler,
L., Brundage, B., Crouse, J., Detrano, R., Fuster, V., Maddahi, J.,
Rumberger, J., Stanford, W., White, R., and Taubert K. 1996.
"Coronary Artery Calcification: Pathophysiology, Epidemiology,
Imaging Methods, and Clinical Implications," Circulation 94(5):
1175-1192).
[0933] The apparatus suitable for use with plaque depends upon the
degree and distribution of mineralization revealed by electron
beam, helical (spiral) computed tomography, or optical coherence
tomography (see, for example, Kubo, T., Imanishi, T., Takarada, S.,
Kuroi, A., and nine other authors 2007. "Assessment of Culprit
Lesion Morphology in Acute Myocardial Infarction: Ability of
Optical Coherence Tomography Compared with Intraductal Ultrasound
and Coronary Angioscopy," Journal of the American College of
Cardiology 50(10):933-939). A combination-form barrel-assembly,
radial projection catheter, or either component in a duplex
(composite, bipartite) barrel-assembly, as addressed below in the
section entitled Distinction in Ablation or Ablation and
Angioplasty-capable Barrel-assemblies as Unitary or Bipartite, can
thus serve midprocedurally, in effect, as a kind of guide catheter
for original equipment manufacturer cabled devices.
[0934] Depending upon the type ductus and barrel-assembly, these
include a laser, rotational burr or cutting blade, suction hose,
aspiration line, as a passageway through which a outlet hose
connected to the muffler of a vortex tube can be passed to direct
either chilled or heated air at the rear surface of the muzzle-head
nose for performing a precautionary angioplasty, for example, or as
a channel to allow blood to flow through and past. When unoccupied
by a cabled device such as for atherectomy or thrombectomy, the
bore through the combination-form barrel-assembly, or its central
channel, can accommodate the silo for stowing an embolic
trap-filter and its actuating direct current powered plunger
(push-type, reciprocating armature or slug, punching, linear)
solenoid, which is simpler and less expensive to produce than an
off-center silo, as will be described in the section below entitled
Embolic Trap Filter in Radial Discharge Muzzle-heads for Use in the
Vascular Tree.
[0935] Used manually apart from an airgun, a radial projection
catheter or a barrel-assembly with radial projection unit
tool-inserts such as side-sweepers with or without a trap-filter
and a heatable turret-motor can serve as an independent apparatus
for mechanical atherectomy and thermal angioplasty. The
barrel-catheter of a duplex barrel-assembly allows size-matched, or
complementary, projection catheters to be slid over the
barrel-assembly as a sleeve that can be retracted to exchange the
tool-inserts midprocedurally without the need to withdraw the
barrel-assembly. The reverse arrangement, passing a barrel-assembly
though the bore of a combination-form radial projection catheter,
is possible but space demanding, awkward, and having limited
application. Certain embodiments allow a carbon or nitrous oxide
cartridge to be plugged into the proximal end-plate for
cryoablation (cryocautery) or the chilling of tissue for metabolic
stabilization (chemical retardation).
[0936] The incorporation of a laser catheter allows a
barrel-assembly to remove plaque that is somewhat calcified and a
rotational atherectomy burr plaque that is stony (hydroxyapatite).
An angioplasty-capable barrel-assembly could be used to prepare the
lumen for the introduction of a conventional or endoluminal stent.
However, it is intended to prepare for an extraluminal stent, then
to implant the intraductal component of that stent with single
entry and withdrawal. Not expandable as is a balloon, for
angioplasty, the body or shell of the muzzle-head is limited to
lumina that match or slightly exceed it in diameter and are
affected by soft atheromatous lesions. Although paths are provided
for blood to pass the muzzle-head even when these diameters match,
below a certain minimum diameter, obstruction to the flow of blood
using a muzzle-head must prove unavoidable.
[0937] Even when flow-around is good, minimizing intracorporeal
time should lead to better results, and several features have been
incorporated to accomplish this. When the diameter of the
muzzle-head is the same or slightly smaller than the diameter of
the lumen, deploying the radial projection units around the
muzzle-head allows an abrasive scrubbing or scraping (curettage,
evidement) action of the surrounding lumen wall. Reciprocal
movement of the barrel-assembly, radial projection catheter, or
duplex barrel-assembly by hand or with the aid of a linear
positioning stage then scrubs down the internal surface of the
lumen in a manner analogous to that of a test-tube brush.
[0938] Depending upon the relative diameter of the apparatus and
lumen, the material properties and adhesion of the lesion, and the
tip type of the brush or side-sweeper type tool-inserts engaged in
the radial projection units, addressed below in the section
entitled Radial Projection Unit Tool-inserts, a side-sweeping type
tool-insert, with or without the aid of an external electromagnet
to urge it against a preferred arc of the surrounding lumen wall,
can be used to obtain a powerful scrubbing or scraping action over
the surrounding wall or an arc thereof. An extracorporeal
electromagnet can aid in steering the muzzle-head or radial
projection catheter, making it easier to pass curved segments.
[0939] As an adjunct to the capabilities for performing an
angioplasty built into the barrel-assembly, an external magnet can
be used with the turret-motor or rotation by hand to urge a certain
arc of the muzzle-head against a certain arc of the lumen wall. The
same does not apply to an independent radial projection catheter
and is not used to ensleeve a barrel-catheter as the duplex
counterpart thereto, which does not have a turret-motor. If the
muzzle-head has clearance all around, this will consolidate and to
the extent short of injury, increase the cross section for blood to
pass. When applied to the proximate side, extension allows
increasing the force applied to the working (cutting, shaving,
abrading, or swabbing) face of the tool-insert on the opposite
side, and when applied to retraction on the near side, reducing
this force.
[0940] Extension of near side push-arm (blank) tool-inserts and
those with brush-like tips too dense to perforate the lumen wall
can be used to push the muzzle-head or projection catheter in the
opposite direction and/or to allow blood to pass. When using an
external magnet, the abruptness of magnetic attraction when the
effective tractive force is reached risks stretching injury and
dissection, recommending restriction of the field strength. The use
of an external electromagnet is therefore limited to ductus or
lengths thereof which have not become significantly weakened by
disease orsignificantly larger in diameter than the muzzle-head or
projection catheter. Excessive distance between the outside of the
apparatus and the wall of the lumen can allow a buildup of momentum
sufficient to deliver a blow to the lumen wall.
[0941] If desired, however, an external magnet allows urging the
muzzle-head against the inside of the lumen wall with greater
force. Depending upon the relative diameter of the lumen and the
muzzle-head or projection catheter and the distance to which the
radial projection unit or units can be extended on the near side,
the application of mild pressure to the opposite lumen wall can be
accomplished with less force than through the use of an external
magnet. In contrast, however, the use of an external magnet to stop
and extract a loose miniball is accomplished least traumatically
the more suddenly the tissue is penetrated; slower extraction is
liable to pull, stretch, or tear the adjacent tissue.
[0942] Accordingly, to extract a miniball, the field strength is
set at the maximum, extraction entirely outside the body or to a
safe location outside the ductus determined by the duration, rate,
and number of pulsed magnet energizations. Whether the same or
different magnets are used for such purposes, the controls should
permit the kinds of adjustments indicated. Further to avoid
dissections and tears, steering of the muzzle-head with the aid of
an extracorporeal hand-held electromagnet or the probe of a large
electromagnet is limited to plaque that does not present calcified
prominences and does not pose excessive resistance to pass. Another
limitation is that setting the field strength too high risks the
extracting of miniballs already implanted on the opposite side.
[0943] The barrel-assembly incorporates several means for
accomplishing angioplasty to ameliorate the limitations imposed by
the restrictedness of the lumen diameter and the hardness of some
lesions. The deployment of radial projection units along any arc of
the barrel-assembly or radial projection catheter can also be used
to nudge the muzzle-head in the opposite direction. When the radial
projection units do not encircle the muzzle-head or are not
situated along the radii desired, the turret-motor is used to
rotate the muzzle-head before the tool-inserts are extended. This
allows the working or blank face of the radial projection unit
tool-insert on the opposite side to be applied with greater force
against the lumen wall but must not be used for steering.
[0944] Radial projection tool-inserts are addressed below under the
section of like title and include electrically and fluidically
operated ejection types that can release a lubricant, liquid drugs,
and/or other therapeutic substances against the lumen wall, as can
unused barrel-tubes. Based upon a preliminary determination of the
distribution and character, that is, the histology, pathology, and
hardness of the plaque (usually by computed tomography), radial
projection unit abradmg or brush type tool-inserts having, for
example, bristles of suitable stiffness and tip conformation are
mounted in the radial projection unit wells (sockets, recesses)
about the muzzle-head.
[0945] Then, using controls onboard the barrel-assembly or the
radial projection catheter rather than an external electromagnet,
the deployment of the radial projection unit or units to one side
of the muzzle-head or catheter allows it to be nudged in the
opposite direction. This allows applying the working or blank faces
of the radial projection unit tool-inserts extended on that side to
be applied with greater force against the lumen wall. Erosive or
ablative action can also be intensified by using the turret-motor
to quickly rotate the muzzle-head or oscillate it by means of
vibratory motion that has been programmed or obtained through servo
destabilization, as discussed below in the section entitled
Turret-motor Operational Modes.
[0946] When different type tool-inserts, such as shavers (skivers)
and brushes, are inserted into the radial projection unit
lift-platforms about the muzzle-head, differential deployment
followed by rotation using the turret-motor or by hand enables the
bringing to bear of tool-inserts in any available combination or
sequence to a given lesion. To avoid perforating the wall, this is
generally limited to flat-faced (push-arm, blank) tool-inserts and
those with aristae or bristles without sharp tips, and those too
dense to puncture. With or without additional force, the
side-sweeper type radial projection unit tool-inserts in an
ablation and angioplasty-capable barrel-assembly or a radial
projection catheter, whether brushes as such or cutting tools, can
be used to perform an ablation or an angioplasty with the
barrel-assembly or catheter moved transluminally by hand or with
the aid of a linear positioning stage.
[0947] When the apparatus is a barrel-assembly, the tool-inserts
can be rotated at any level manually or with the turret-motor,
which primarily to support the use of injection syringe
tool-inserts, also allows fine adjustment in rotational angle. With
the barrel-assembly not removed from the airgun, which would free
its proximal end and length adjacent thereto for manual use, the
airgun linear positioning table (linear positioning stage) can be
used to move the muzzle-head. The base upon which the linear
positioning stage is mounted positions the airgun in the
proximodistal direction. Thus, provided the barrel-assembly is not
already fully intromittent (intracorporeal), an additional length
of barrel-catheter needed to further advance transluminally is made
available by shifting the airgun mounting closer to the patient
with the positioning stage.
[0948] Angioplasty or any other treatment, such as injection or
ablation, can therefore be resumed with the barrel-assembly left in
the airgun, that is, without detaching the barrel-assembly after it
has already been inserted into the airgun: Most ablation and
angioplasty can be accomplished manually with the barrel-assembly
separate from an airgun; adjustment in transluminal positioning
requiring precision as to recommend mechanical positioning pertains
primarily to discharge and further discharge in a uniform dense
pattern. When the barrel-assembly is already fully intromittent up
to the power and control housing and must be advanced further
distally, the housing is shifted back, or slid proximally, along
the barrel-catheter to provide an additional length of
barrel-catheter to its fore for intromission.
[0949] The opposite situation of requiring continued withdrawal of
the muzzle-head past the retractive range of the linear stage is
handled the same way but in the opposite direction. The linear
positioning stage used should have a sufficient range (throw, bed
length) to move the barrel-assembly muzzle-head or the radial
projection catheter across the entire treatment site. However, if
the stage, which supports and is attached to the airgun, has
already reached the distal limit of its range, resumption in the
use of the linear stage requires shifting the base upon which the
stage is mounted closer to the patient.
[0950] Whether to shift the stage base distally (forward) or
backward (proximally), this action must be accomplished without
disturbing or affecting the transluminal position of the
muzzle-head. To do this, the otherwise stationary base or bed of
the linear stage, which is slidably joined to the stage, must be
repositioned in the distal direction (closer to the patient)
without affecting the position of the airgun or the stage. The
simplest way to accomplish this is by gently lifting the airgun
with attached linear stage free of the cart surface manually, and
then using the stage control to shift (translate) the base of the
linear stage distally (closer to the patient) leaving the airgun
unaffected in position.
[0951] That is, whereas with the linear stage in contact with the
cart the base remains stationary and drives the stage with attached
airgun, by lifting the base free of the cart, the airgun with
attached linear stage remain stationary as the base moves forward.
When the airgun with stage and mounting are set down, the stage
will be positioned to allow a resumption in forward (distal)
motion. To accomplish the same action without manual intervention,
the linear stage must be provided with an additional joint or
planar interface on its underside, that without affecting the
position of the airgun, allows the separate linear translation of
the base between the stage above and cart below. To do this, the
base is attached down to a position controllable motorized carriage
or creeper with a continuous loop or full track conveyor belt
beneath that circulates between pulleys at either end.
[0952] Such a device, effectively an inverted linear stage which is
not limited in range of linear motion, could replace the linear
stage, but is less precise than a stage, not a standard component
for motional control applications, and is not needed when the
distance to be covered falls within the range of the stage, as is
usual. The upper stage repositions the airgun to a point in its
range that will allow continued travel in the direction required
while the base mover simultaneously repositions the upper stage in
the opposite direction. The result is that the upper stage is
shifted as needed without movement of the airgun. To carry the
stage and airgun, the motor used to drive the base must be as or
slightly more powerful than that built into the stage. Both motors,
usually stepper motors, are controlled by the same signal.
[0953] The base can now crawl or creep along the surface of the
cart in synchrony with the corresponding (equal but opposite)
repositioning of the stage, thus repositioning the stage to resume
movement of the barrel-catheter past either the proximal or distal
limit of its integral bed. The additional axis and control
electronics therefor add complexity and expense viewed as
nonessential. Ablation and ablation and angioplasty-capable
barrel-assemblies include components, to include radial projection
units, heatable turret-motors, and recovery (tractive)
electromagnet windings, that can be used to perform an ablation,
atherectomy, or angioplasty by hand with the barrel-assembly
separate from the airgun. As opposed to its heating or thermal mode
of operation, the turret-motor positioning and oscillatory
functions are disabled during discharge.
[0954] Heating during discharge will, however, necessitate
adjustment in the propulsive force of discharge, which to avert
human error, is best incorporated into the control circuitry as
automatic. While oscillatory movement can be programmed, the
oscillatory capability of the turret-motor inheres in closed loop
control by intentional overamplification and does not require
additional parts or modifications. Driven as is a membrane
peeler-cutter or microscissors for intraocular surgery, the viscous
or dashpot damped trap-filter plunger (punching, push-type,
reciprocating armature or slug) solenoid in the nose of the
muzzle-head can be made to linearly reciprocate at a high frequency
in the longitudinal axis. Such action can be used to add a
reciprocating oscillatory component at the nose of the muzzle-head
to that rotatory obtained through use of the turret-motor.
[0955] Alternative methods for inducing oscillation of the
muzzle-head include movably mounting each recovery electromagnet so
that the pull of each acts upon the other and sidewise upon the
plunger solenoid as it reciprocates to vibrate the nose of the
muzzle-head. Positional control of the turret-motor defines the
limits of rotation that if exceeded would cause distortion of the
barrel-tubes leading to constriction or jamming during discharge.
Stops on the shell of the muzzle-head further protect against
excessive rotation in the event of a malfunction. Control within
the permissible rotational angle of the muzzle-head during an
angioplasty, for example, allows eccentric lesions to be targeted
for treatment with adjacent arcs affected less if at all.
[0956] With adequate contrast, the point of injection can be
adequately limited, whereas less focused treatments, such as the
application of heat or cold, will spread or spill over in
proportion to the intensity thereof. Control over the turret-motor,
thus the muzzle-head rotational angle, allows directing a
heat-window or windows or a tool-insert or inserts to a certain
arc. Programmed vibratory motion with the rate of reciprocation
controlled or intentionally induced turret-motor control circuit
servo-oscillation can be used to provide a scrubbing or swabbing
action for use with deployed (extended, projected) abrading,
cutting, or swabbing tool-inserts as appropriate.
[0957] The same action can be used to assist in passing a tortuous
stretch of ductus with or without the release of a catheteric
lubricant from ejection tool-inserts, through barrel-tubes, or if a
combination-form barrel-assembly or radial projection catheter, the
central bore or channel Suitable lubricants are specified in the
section below entitled Multiple Radial Discharge Barrel-assemblies
with One- to Four- or More-way Radial Discharge Muzzle-heads. By
comparison, a balloon used for arterial thermoplasty or cryoplasty
is not compartmentalized to deal with eccentric lesions. By
definition, an ablation or angioplasty-capable barrel-assembly must
be self-contained for use independently of an airgun without regard
to previous or subsequent use for ballistic implantation.
[0958] Such capability necessitates an onboard control panel and
electrical power source. An onboard rechargeable lithium-ion
polymer electrolyte (lithium polymer, Li-poly, LiPo) battery pack,
preferably of the thin film kind for increased charge-discharge
cycles, allows an ablation or ablation and angioplasty-capable
barrel-assembly to be used independently of the airgun or other
power supply and without a power cord. Angioplasty or ablation with
the barrel-assembly is thus performed manually without restraint
due to connection at the rear. When matched with a combination-form
radial projection catheter to constitute a duplex or bipartite
ablation or angioplasty-capable barrel-assembly, the control
housings of the two components, each slidable along the length of
its respective component, are placed in apposite or ganged
relation.
[0959] In addition to these ablation and angioplasty-supporting
operational modes of the turret-motor, both it and the tractive
electromagnets within the barrel-assembly support discharge,
recommending the incorporation of controls on a panel mounted to
the outside of the airgun with an independent power source housed
within. Whether duplicated on the airgun, mounted onboard the
barrel-assembly, these controls allow directing the turret-motor to
execute changes in rotational angle for aiming or targeting, and
allow separate variability in the field strength of either tractive
electromagnet within the barrel-assembly for recovery or extractive
use. The barrel-assembly is used apart from the airgun for ablation
or angioplasty and must be inserted into the airgun only to
discharge miniballs, whether stenting or therapeutic.
[0960] The manual use of a separate combination-form radial
projection catheter that is the complement to a duplex
barrel-assembly which remains engaged in the airgun and is passed
through the projection catheter so that the muzzle-head is brought
to the position at which discharge is to be initiated as necessary
is also possible. The proximal end of an ablation or
angioplasty-capable barrel-assembly can be inserted into the
interventional airgun for stenting at any time during as well as
following a preparatory angioplasty performed manually with the
same apparatus. If the angioplasty is performed using the
positional control system, then the barrel-assembly will already
have been engaged in the airgun.
[0961] While balloon angioplasty alone can return the lumen to
substantial concentricity, the sites of harder lesions experience
greater radial force, sometimes resulting in dissections leading to
increased arterial shrinkage, or constrictive remodelling, and
intimal hyperplasia. A preliminary reduction of prominences by
means of cutter balloon or rotational, directional, ultrasonic, or
laser-catheter atherectomy reduces the risk of this eventuality,
and this has encouraged the development of catheter-based devices
that cut and then reduce rather than merely smash plaque whether a
stent is then used, which can serve to hold the resultant debris in
place. Especially when equipped with radial projection units or as
combination-forms that incorporate a laser or cutting tool,
ablation or ablation and angioplasty-capable barrel-assemblies can
be used to perform an ablation or an angioplasty or atherectomy
independently of an airgun.
[0962] Using either an edge- or center-discharge muzzle-head, these
differ from the use of balloons in ways that as an alternative
technology and methodology, offer advantages as compared to the use
of balloons. Not inflated and not over-inflatable, provided it is
properly sized, the muzzle-head is less prone to cause dissections
and does not require to be withdrawn through the introducer sheath
for reentry to introduce a stent. Instead, stenting is initiated
without a second radial inflation against the lumen wall in order
to expand an endoluminal stent with sufficient force to prevent
migration; to initiate stenting, the free end of the
barrel-assembly is plugged into the airgun. By the same token, the
muzzle-head is not deflatable, which capability of a balloon
reduces the risk of tears and ischemia.
[0963] Commercial cabled devices incorporated into a
barrel-assembly, radial projection catheter, or a combination-form
thereof with a central bore, such as a laser or rotational
atherectomizer requiring connection to an original manufacturer
equipment control console will continue to necessitate cabling.
Tethering by means of a loose cable connected to the rear (proximal
end) of the barrel-assembly is less restraining than is
immobilization of the proximal end by virtue of insertion into the
airgun barrel. When the barrel-assembly incorporates a laser or
atherectomy device, the cable for these is used as well. Directly
connecting the components in the barrel-assembly to the airgun
power supply by means of a cable without the need to insert the
barrel-assembly into the airgun barrel allows the barrel-assembly
to be made at lower cost.
[0964] However, this difference is generally not considered
sufficient to offset the loss in the barrel-assembly as a
stand-alone or independent device. Otherwise, cabled devices can
almost always be adapted to incorporate the control electronics and
power source within the onboard control housing. Accordingly, in an
ablation or ablation and angioplasty-capable barrel-assembly which
can be used separately from the airgun, the controls for use of the
components included are located on a control panel mounted to the
side of the onboard power and control housing. These controls allow
heating the turret-motor stator, deploying radial projection unit
tool-inserts, and the use of any other components. Control panels
are addressed below in the section entitled Ablation and Ablation
and Angioplasty-capable Barrel-assembly Onboard Control Panel and
the housing below in the section entitled Barrel-assembly Power and
Control Housing.
[0965] Radial projection catheters have a similar housing and
control panel, which is adjacent to that of the barrel-assembly
when these are mated in a duplex type barrel-assembly. For heating
the turret-motor, the motor drive electronics that ordinarily
convert the applied dc into 3 phase current is bypassed. A radial
projection catheter is capable of performing any endoluminal
procedure, and an ablation or angioplasty-capable barrel-assembly
can also place (implant) the intravascular component of any number
of extraluminal stents. Neither uses a guide wire. The
deflatability of a balloon minimizes the risk of occlusive hypoxia
and enhances movement past stenotic and tortuous stretches, but is
associated with the need for a guide wire and the risks a guide
wire carries.
[0966] Neither does a balloon make possible the integration of
additional function beyond thermoplasty by running a heated liquid
or cryoplasty by running a chilled liquid through it. A cutting
balloon can also atherectomize, but no balloon can perform an
angioplasty or an atherectomy and then stent without the need to
withdraw and reenter, thus reducing the risk of entry wound
complications. A balloon can stent without an angioplasty, but, the
endoluminal stent it places will often create problems later that
an extraluminal stent will not. By the same token, the endoluminal
stent does not require extraluminal as well as endoluminal access.
Catheter-based devices currently in use do not lend themselves to
such a combination of functions or to the ability to place multiple
stents. Apart from difficulties in integrating the devices
mechanically, some are not reusable.
[0967] A distinguishing attribute of the apparatus to be described
is the possibility of integrating numerous therapeutic functions.
While relaxed or having had the normal angiotensive or contractive
force exerted by the smooth muscle in the wall of the vessel
reduced by administering medication, the lumen wall allows
transluminal access to narrower portions of the vascular tree with
a barrel-assembly of given diameter. Once placed, however, an
extraluminal stent should require relatively little medication. A
barrel-assembly that is wider in diameter can incorporate more
features and deliver more miniballs per discharge, reducing
procedural time. The narrowness of the lumina in the vascular tree
makes a safe means of dilatation advantageous.
[0968] The blunt and slippery nose of the muzzle-head poses little
risk of perforations, and made of tough, flexible, and strongly
bonded polymer tubing, the entire apparatus less still of
fractures. The barrel-assembly is thus capable of traversing
tortuous stretches of vessels that a guide wire could perforate.
Without a guidewire, the application of an off-the-shelf magnetic
navigation system such as provided by Stereotaxis, Inc., St. Louis,
Mo. and IntraLuminal Therapeutics Division, Kensey Nash, Inc.,
Carlsbad, Calif., now Spectranetics, Inc., Colorado Springs, Colo.,
is to the muzzle-head itself, which can be coordinated with the
positional control system.
[0969] Except in certain combination-form barrel-assemblies, the
elimination of a guidewire offers the benefit of eliminating
various complications, which infrequent, can prove catastrophic
when these occur, to include:
[0970] a. Perforations (see, for example, Storger, H. and Ruef, J.
2007. "Closure of Guide Wire-induced Coronary Artery Perforation
with a Two-component Fibrin Glue," Catheterization and
Cardiovascular Interventions 70(2):237-240; Shirakabe, A., Takano,
H., Nakamura, S., and thirteen other authors 2007. "Coronary
Perforation During Percutaneous Coronary Intervention,"
International Heart Journal 48(1):1-9; Axelrod, D. J., Freeman, H.,
Pukin, L., Guller J., and Mitty, H. A. 2004. "Guide Wire
Perforation Leading to Fatal Perirenal Hemorrhage from
Transcortical Collaterals after Renal Artery Stent Placement,"
Journal of Vascular and Interventional Radiology 15(9):985-987;
Naik, M., Lau, K.-W., and Chua Y.-L. 2001. "Guidewire Perforation
during PTCA with Subsequent Off-Pump Bypass Surgery," Texas Heart
Institute Journal 2001 28(1):70-71; Witzke, C. F., Martin-Herrero,
F., Clarke, S. C., Pomerantzev, E., and Palacios, I. F. 2007. "The
Changing Pattern of Coronary Perforation During Percutaneous
Coronary Intervention in the New Device Era," Journal of Invasive
Cardiology 16(6):257-301; Kent, J. and Nedumpara, T. 2007.
"Perforation of the Gall Bladder by a Peripherally Inserted Central
Catheter Guidewire: `If it Can Happen it Will,` Australia-New
Zealand Journal of Surgery 77(3):190-191; Ogino, H., Miki, S.,
Ueda, Y., Tahata, T., Morioka, K., and Sakai, T. 1995. "A Rare Case
of Coronary Artery Perforation by a PTCA Guide Wire Complicated by
Postinfarction Cardiac Rupture after Thrombolytic Therapy," (in
Japanese) Nippon Kyobu Geka Gakkai Zasshi 43(8):1151-1154).
[0971] b. Fractures (see, for example, Kilic, H., Akdemir, R., and
Bicer, A. 2008. "Rupture of Guide Wire During Percutaneous
Transluminal Coronary Angioplasty, a Case Report," International
Journal of Cardiology 128(3):e113-e114; Collins, N., Horlick, E.,
and Dzavik, V. 2007. "Triple Wire Technique for Removal of
Fractured Angioplasty Guidewire," Journal of Invasive Cardiology
19(8):E230-234; Vrolix, M., Vanhaecke, J., Piessens, J., and De
Geest, H. 2005. "An Unusual Case of Guide Wire Fracture during
Percutaneous Transluminal Coronary Angioplasty," Catheterization
and Cardiovascular Diagnosis 15(2):99-102; Gavlick, K. and
Blankenship, J. C. 2005. "Snare Retrieval of the Distal Tip of a
Fractured Rotational Atherectomy Guidewire: Roping the Steer by its
Horns," Journal of Invasive Cardiology 17(12):E55-E58; Kim, J. Y.,
Yoon, J., Jung, H. S., Kim, W. J., Yoo, B. S., Lee, S. H., and
Choi, K. H. 2005. "Broken Guidewire Fragment in the Radio-brachial
Artery During Transradial Sheath Placement: Percutaneous Retrieval
via Femoral Approach," Yonsei Medical Journal
28;46(1):166-168).
[0972] c. Fractures necessitating emergency surgical retrieval
(see, for example, Modi, A., Zorinas, A., Vohra, H. A., and Kaarne,
M. 2011. "Delayed Surgical Retrieval of Retained Guidewire
Following Percutaneous Coronary Intervention," Journal of Cardiac
Surgery 26(1):46-48;.Demirsoy, E., Bodur, H. A., Arbatli, H., Ya
an, N., Yilmaz, O., Tukenmez, F., Ozturk, S., and Sonmez, B. 2005.
"Surgical Removal of Fractured Guidewire with Ministernotomy," (in
English) Anadolu Kardiyoloji Dergisi (Anatolian Journal of
Cardiology) 5(2): 145-477 (available at
http://www.anakarder.com/sayilar/21/2005-145-147.pdf).
[0973] d. Entrapment with or without fracture necessitating
emergency surgical extraction and a coronary artery bypass graft
(Capuano, F., Simon, C., Roscitano, A., and Sinatra, R. 2008.
"Percutaneous Transluminal Coronary Angioplasty Hardware
Entrapment: Guidewire Entrapment," Journal of Cardiovascular
Medicine (Hagerstown) 9(11):1140-1141; Darwazah, A. K., Abu Sham'a,
R. A., Yassin, I. H., and Islim, I. 2007. "Surgical Intervention to
Remove an Entrapped Fractured Guidewire during Angioplasty,"
Journal of Cardiac Surgery 22(6):526-528; Kim, C. K., Beom Park,
C., Jin, U., and Ju Cho, E. 2006. "Entrapment of Guidewire in the
Coronary Stent During Percutaneous Coronary Intervention," Thoracic
and Cardiovascular Surgeon 54(6):425-426).
[0974] e. Fractures with entrapment (see, for example Marti, V. and
Markarian, L. 2007. "Atrapamiento de la guia de angioplastia
despues de la implantacion de un stent: Descripcion de dos casos y
revision de la literatura," ("Angioplasty Guidewire Entrapment
Following Implantation of a Stent: Description of Two Cases and a
Review of the Literature") Archivos de cardiologia de Mexico
77(1):54-57; Kim, C. K., Beom Park, C., Jin, U., and Ju Cho, E.
2006. "Entrapment of Guidewire in the Coronary Stent During
Percutaneous Coronary Intervention," Thoracic and Cardiovascular
Surgeon 54(6):425-426; Ozkan, M., Yokusoglu, M., and Uzun, M. 2005.
"Retained Percutaneous Transluminal Coronary Angioplasty Guidewire
in Coronary Circulation," Acta Cardiologica 60(6):653-654;
Khambekar, S., Hudson, I., and Kovac, J. 2005. "Percutaneous
Coronary Intervention to Anomalous Right Coronary Artery and
Retained Piece of Guidewire in the Coronary Vasculature," Journal
of Interventional Cardiology 18(3):201-204;
[0975] f. Fractures with entrapment necessitating emergency
percutaneous retrieval (see, for example Khong, P. L. and John, P.
R. 1997. "Percutaneous Retrieval of a Fractured Biliary Guidewire
from a Reduced Liver Graft," Pediatric Radiology 27(3):253-254;
Pande, A. K. and Doucet, S. 1998. "Percutaneous Retrieval of
Transsected Rotablator Coronary Guidewire Using Amplatz "Goose-Neck
Snare"," Indian Heart Journal 50(4):439-442; Savas, V., Schreiber,
T., and O'Neill, W. 1991. "Percutaneous Extraction of Fractured
Guidewire from Distal Right Coronary Artery," Catheterization and
Cardiovascular Diagnosis 22(2): 124-126).
[0976] g. Fractures with entrapment necessitating emergency
surgical intervention (see, for example, Darwazah, A. K., Abu
Sham'a, R. A., Yassin, I. H., and Islim, I. 2007. "Surgical
Intervention to Remove an Entrapped Fractured Guidewire During
Angioplasty," Journal of Cardiac Surgery 22(6):526-528; Goksin, I.,
Baltalarli, A., Semiz, E., Gurses, E., Sacar, M., Ozcan, V., and
Sungurtekin, H. "Catheter Entrapment During Balloon Angioplasty in
Patient with In-stent Restenosis: An Unusual Complication and Its
Surgical Management," Journal of Cardiac Surgery 2007
22(2):160-162).
[0977] A similar set of risks pertains to balloon catheters (see,
for example, Hung, C. L., Tsai, C. T., and Hou, C. J. 2004.
"Percutaneous Transcatheter Retrieval of Retained Balloon Catheter
in Distal Tortuous Coronary Artery: A Modified Double-helix
Approach," Catheterizaton and Cardiovascular Interventions
62(4):471-475; Hwang, M. H., Hsieh, A. A., Silverman, P., and Loeb,
H. S. 1994. "The Fracture, Dislodgement and Retrieval of a Probe
III Balloon-on-a-Wire Catheter," Journal of Invasive Cardiology
6(5):154-156). Thus, whenever a combination-form barrel-assembly
can be made to duplicate the function of a normally independent
guidewire-directed device, it is preferred to incorporate the
function into the barrel-assembly without the guidewire. Numerous
such devices, to include radio frequency ablative guidewires and
excimer lasers can be readily incorporated without a guidewire.
[0978] A combination-form barrel-assembly with side-socket can
nevertheless be used with proprietary devices such as the optical
coherence reflectometry-guided Safe-Cross.RTM. Radiofrequency Total
Occlusion Crossing System from Spectranetics, Incorporated. Except
through tortuous stretches, such function would more often be
obtained through use of a laser that has been built into an
ablation and angioplasty-capable or inserted into a
combination-form barrel-assembly or radial projection catheter. The
use of an extracorporeal electromagnet, hand-held or mounted, is
described below in the section entitled Steering and Emergency
Recovery of Implants with the Aid of an External (Extracorporeal)
Electromagnet. The magnet is adjusted to the minimal field strength
sufficient to act as an aid to steering. Such use is addressed
above in the section entitled Administration of Target and
Target-adjacent Implantation Preparatory Substances.
[0979] In addition to the use of an external electromagnet, the
muzzle-head, while greater in mass as to necessitate a stronger
magnetic field, is compatible with recent advancements in magnetic
navigation (see, for example, Rivero-Ayerza, M., Jessurun, E.,
Ramcharitar, S., van Belle, Y., Serruys, P. W., and Jordaens, L.
2008. "Magnetically Guided Left Ventricular Lead Implantation Based
on a Virtual Three-dimensional Reconstructed Image of the Coronary
Sinus," Europace 10(9):1042-1047; Kiemeneij, F., Patterson, M. S.,
Amoroso, G., Laarman, G., and Slagboom, T. 2008. "Use of the
Stereotaxis Niobe Magnetic Navigation System for Percutaneous
Coronary Intervention: Results from 350 Consecutive Patients,"
Catheterization and Cardiovascular Interventions 71(4):510-517;
Schneider, M. A., Hoch, F. V., Neuser, H., Brunn, J., and 5 others,
2008. "Magnetic-guided Percutaneous Coronary Intervention Enabled
by Two-dimensional Guidewire Steering and Three-dimensional Virtual
Angioscopy: Initial Experiences in Daily Clinical Practice,"
Journal of Interventional Cardiology 21(2):158-166).
[0980] A magnetic navigation system can also be coordinated with
the use of the positional control system. The latter does not steer
but rather transluminally moves the muzzle-head while controlling
its angular orientation. Such use is appropriate when the
muzzle-head is narrower than the lumen and drawing the exit port
flush against the lumen wall does not irremediably compress the
lumen wall so that it is too narrow to implant, as will be
addressed. The relative merits of femoral and radial access have
been widely studied (see, for example, Archbold, R. A., Robinson,
N. M., Schilling, R. J. 2004. "Radial Artery Access for Coronary
Angiography and Percutaneous Coronary Intervention," British
Medical Journal 329(7463):443-446; Louvard, Y., Lefevre, T.,
Allain, A., and Morice, M. 2001. "Coronary Angiography through the
Radial or the Femoral Approach: The CARAFE Study," Catheterization
and Cardiovascular Interventions 52(2):181-187; Kiemeneij, F.,
Laarman, G. J., Odekerken, D., Slagboom, T., van der Wieken, R.
1997. "A Randomized Comparison of Percutaneous Transluminal
Coronary Angioplasty by the Radial, Brachial and Femoral
Approaches: The Access Study," Journal of the American College of
Cardiology 29(6):1269-1275. Angioplasty preceding stenting is
preferably accomplished with an angioplasty-capable
barrel-assembly, which can proceed from or switch between the one
process and other without the need to withdraw and reenter.
[0981] Whenever preceded by a conventional (balloon) angioplasty,
access, whether percutaneous or open, is preferably at the same
groin (inguinal, femoral) entry wound as was used for the
angioplasty, with the administration of heparin having been
stopped. This is because 1. Proximal, meaning brachial or
`axillary` (high brachial), much less radial access poses a greater
risk of complications, 2. Groin (femoral artery or vein)
compression closure aids such as the
FemoStop.RTM.Plus,Angio-Seal.RTM.STS Plus and Millenium platforms,
and Perclose.RTM.A-T have become available to deal with oozing or
hematoma, 3. Stenting almost always follows balloon angioplasty or
rotational (rotablation), directional, or transluminal extraction
coronary atherectomy, and requiring withdrawal and reentry takes
more time and can aggravate the entry wound, 4. The muzzle-head at
the end of the barrel-assembly is generally 8-10 French,
recommending an entry wound of larger size, 5. A point of entry
other than inguinal increases the possibilities for puncture site
complications and postoperative morbidity. When the angioplasty is
accomplished using an angioplasty-capable barrel-assembly, removal
of one catheter and insertion of another is unnecessary.
8. Concept of the Extraluminal Stent
[0982] Three basic types of extravascular (circumvascular,
circumductal, periductal, perivascular) stent component are
addressed. These include ordinary stent-jackets, which are based
upon a length of elastic tubing that if not intrinsically
magnetized, laminated, or encased within a coating that
incorporates a magnetized lanthanoid, for example, are provided
with small permanent magnets mounted about the outer surface.
Intrinsically and quasi-intrinsically magnetized components
offering no visible indication of magnetization, for clarity,
extrinsic magnets are shown in the drawing figures; however, for
compactness and to avoid encroaching upon neighboring tissue, most
practical components are intrinsically or quasi-intrinsically
magnetized.
[0983] A second type is the longitudinally segmented, or spine and
ribs-configured stent-jacket for use along peristaltic ductus,
where a stent-jacket that is able to comply only circumferentially
would lack the flexibility needed to comply with longitudinally
consecutive extremes in radial excursion. Impasse-jackets are
primarily devised for use other than to keep a lumen patent, but
when necessary or beneficial, can also be used to stent. A fourth
type, the magnet-jacket, is devised to be placed about a substrate
ductus for directing magnetic force radially outward; if used for
its inward force, it is a stent-jacket. In many locations, a
nonabsorbable endoluminal stent that will be needed over a longer
period than an absorbable stent would last is practically
irretrievable.
[0984] This is due more to the trauma that recovery would produce
than it is to a desire to avoid subjecting the patient to a second
invasive procedure, despite the potential harm that leaving the
stent in might cause and the benefit that removing it would
provide. The chronic irritation and physiological disruption caused
by an endoluminal stent stimulates the ductus to adapt; however,
adaptation equates to suboptimal function, can itself cause
complications, may be inadequate, or prove adequate for only a
limited time. The advent of absorbable endoluminal stents will
eliminate some problems encountered with nonabsorbable endoluminal
stents, but introduce others. Once absorbed, the patient is left
entirely and interminably dependent upon a statin, and for about a
year following, a platelet blocker.
[0985] A chronic condition such as vasospasm refractory to drugs or
a condition that for pathophysiological or genetic reasons is
predicted but not as to time, cannot be preempted at potential
points of critical blockage by prepositioning an absorbable stent.
As a mechanical means for maintaining patency without interfering
with intrinsic motility, an extraluminal stent affords a measure of
protection against restenosis that should allow reducing the
frequency of drug use. This is especially true when the
intravascular component consists of stays, which are introduced
from outside the artery so that the lumen is entered only when a
preparatory angioplasty is performed. Stays may allow.the use of a
platelet blocker to be avoided.
[0986] The use of impasse-jackets as delineated below in the
sections entitled Concept of the Impasse-jacket and Cooperative Use
of Impasse-jackets in Pairs and Gradient Arrays, among others,
presents means that allow the highly localized administration of a
statin in higher concentration than could be introduced into the
systemic circulation without risking liver and muscle
complications. Platelet blockers such as clopidogrel, aspirin, and
others indicated above in the section entitled Prevention of Abrupt
Closure with Thrombus and Vasospasm should be avoided with a
patient prone to peptic ulcer disease and/or hypersensitivity to
these. Clopidogrel and similar drugs pose a risk of intracranial
hemorrhage, can create a bleeding problem for emergency surgery,
and can cause hypertension, hypercholesterolemia, upper respiratory
or urinary tract infection, bronchitis, chest and/or
musculoskeletal pain, headache, dizziness, diarrhea, epistaxis,
purpura, pruritis, rash, edema, nausea, and emesis.
[0987] Vorapaxar (Merck Sharp Dohme/Schering-Plough), a thrombin
receptor antagonist, can cause bleeding as may disallow use in
patients with a history of stroke. Unlike an implantable
cardioverter-defibrillator, for example, an absorbable stent is not
prepositionable to protect against a post absorption condition for
which the patient is at risk or when the need for a stent can be
predicted, as will become more significant when genomic diagnosis
attains confidence. An absorbable stent is also useless with a
condition that proves refractory to medication as do some cases of
coronary vasospasm. Where an absorbable stent is indicated, an
absorbable extraluminal stent can be used, as addressed above in
the section entitled Absorbable Stent-jackets, among others.
[0988] Furthermore, the development of endoluminal stents that are
absorbed more slowly will not change the basic mechanics, although
these might leave the ductus having adapted with limited ability to
readapt when the stent is gone. By contrast, once healed, an
extraluminal stent does not disrupt function, certainly not
approaching that of an endoluminal stent, so that the patient
seldom gains benefit from its removal. Moreover, since absorbable
extraluminal stens can be provided, even the negligible disruption
an extraluminal stent might induce can be avoided. That once the
ductus fully heals an extraluminal stent would seldom warrant
removal attests to a compliance with physiological function and
avoidance of chronic irritation such that to remove it would not
benefit the patient.
[0989] Ordinary stent-jackets are addressed below in the section
entitled Stent-jackets and Stent-jacket Supportng Elements among
others; rib and spine-type stent-jackets for use along the
digestive tract, in the section below entitled The Extraductal
Component of the Extraluminal Stent and the Means for its
Insertion, among others; and impasse-jackets, used to hold or trap
miniballs or drug carrier bound drugs, in the sections entitled
Concept of the Impasse-jacket and Miniball and Ferrofluid-borne
Particle-impassable Jackets, or Impasse-jackets, among others. The
primary advantage in extraluminal or circumductal stents is the
elimination from within the lumen of a foreign object, which is the
source of the adverse sequelae experienced with these.
[0990] Absence from the lumen means that no obstruction to future
transluminal treatment has been introduced. This is true not only
of stent-jacket but impasse-jackets as well. Extraluminal stents
can incorporate radioisotope and medicinal means to suppress
reocclusion. Where these are inadequate and the adventitial or
fibrosal and abaxial tissue subjacent thereto would not be
irrecoverably injured, another major advantage is that the
extraluminal stent can incorporate sufficient continuous
magnetically permeable material that reocclusion in the mantled
segment can later be cleared by noninvasive thermoplasty
accomplished by placing the patient in a high frequency alternating
magnetic or lower frequency electromagnetic induction field.
[0991] Stent-jackets must not be so strongly magnetized as to pull
miniballs through the adventitia or fibrosa or cause the wall of a
ductus to delaminate. Use with clasp-wraps requires stronger
magnetization, making stent-jackets used to stent incompatible with
these. The use of a stent-jacket to attract susceptible matter from
the lumen likewise tends to require stronger magnetization than is
used to pull the miniball or stay ductus-intramural implants
radially outward, making such application dependent upon the
magnetic susceptibility of the dispersant within the lumen. At the
same time, such warming can be used to accelerate the uptake of
therapeutic substances, such as a statin drug. Uptake can be
further accelerated by attaching the drug to magnetically
susceptible drug carrier particles or nanoparticles.
[0992] Where injury to the intervening adventitia is risked,
reocclusion is can be reduced by periodic imaging and the
application of the inductive field to raise the temperature to no
higher than needed to arrest mitosis (see, for example, Sushkov, F.
V. and V. V. Portugalov 1975. "Temperature Limits of Mitosis in
Mammalian Cell Cultures," Bulletin of Experimental Biology and
Medicine 80(6):1491-1493, Suga, E., Kenji, K., Futami, H.,
Yamashita, E., and Arai, T. 2005. "Prevention of Intimal
Hyperplasia Using Short-period Vascular Heating Without Surrounding
Tissue Injury: In Vitro/In Vivo Experiments and Thermal Conduction
Calculation," Society of Photo-Optical Instrumentation Engineers
Conference Volume 5686, Photonic Therapeutics and Diagnostics
5686:48-446; Edwards, M. J., Mulley, R., Ring, S., and Wanner, R.
A. 1974. "Mitotic Cell Death and Delay of Mitotic Activity in
Guinea-pig Embryos Following Brief Maternal Hyperthermia," Journal
of Embryology and Experimental Morphology 32(1):593-602).
[0993] The onset of restenosis following transluminal procedures is
immediate and usually realized fully within the succeeding six
months (see, for example, Tamai, H., Berger, P. B., Tsuchikane, E.,
Suzuki, T., Nishikawa, H., Aizawa, T., and 6 others 2004.
"Frequency and Time Course of Reocclusion and Restenosis in
Coronary Artery Occlusions after Balloon Angioplasty versus Wiktor
Stent Implantation: Results from the Mayo-Japan Investigation for
Chronic Total Occlusion (MAJIC) Trial," American Heart Journal
147(3):E9; Nakagawa, Y., Iwasaki, Y., Kimura, T., Tamura, T.,
Yokoi, H., and 4 others 1996. "Serial Angiographic Follow-up after
Successful Direct Angioplasty for Acute Myocardial Infarction,"
American Journal of Cardiology 78(9):980-984). Subsequent chilling
allows mitotic arrest by means of heat shock (see, for example,
Bergan, P. 1960. "Blocking of Mitosis by Heat Shock," Nature
186:905-906; Vidair, C. A., Doxsey, S. J., and Dewey, W. C. 1993.
"Heat Shock Alters Centrosome Organization Leading to Mitotic
Dysfunction and Cell Death," Journal of Cellular Physiology
154(3):443-455; Connolly, E. M., Kelly, C. J., Chen, G., O'grady,
T., Kay, E., Leahy, A., and Bouchier-Hayes, D. J. 2003.
"Pharmacological Induction of HSP27 Attenuates Intimal Hyperplasia
in Vivo," European Journal of Vascular and Endovascular Surgery
25(1):40-471).
[0994] The application of heat has many other uses palliative and
therapeutic, as addressed below in the section entitled Laminated
Stent-jackets, for example. Field strength, or frequency and
amplitude versus temperature data are provided with the implant,
which may be any of those described herein, to include
stent-jackets, impasse-jackets, magnet-wraps, clasp-magnets,
miniballs, and stays. That extraluminal placement eschews the
drawbacks of endoluminal placement means that extraluminal
placement offers preventive measures not available using
conventional means. For example, the operator who stretches a
segment of the ductus can preposition a chain-stent over the
affected segment less corresponding ductus-intramural implants,
allowing later thermoplasty to remedy the reocclusion due to
hyperplasia that is predictable in such a case.
[0995] If necessary, the stent prepositioned for thermoplasty can
be supplemented by placing the miniballs that had been omitted so
that the jacket is secondarily converted into the extraductal
(extravascular) component of an extraluminal stent. In situations
where a permanent endoluminal stent as a preventive measure would
be contraindicated, an absorbable endoluminal stent could be
applied only if the period it would be required and its persistence
were known. In such situation, an extraluminal stent, the presence
of which should rarely pose the risk of complications, can be used.
A uniform subadventitial distribution of superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder would
evenly distribute the tension on the retracted tissue under the
force of the magnets, but to accomplish implantation thus is
needlessly complex.
[0996] Unencapsulated elemental iron in the body is readily
oxidized, dispersed, and absorbed and therefore requires a
protective coating regardless of conformation. When an
intrinsically or impregnated coating magnetized stent-jacket cannot
be used, small neodymium magnets are used not to obtain forceful
fields, but to minimize the size of the magnets necessary to
produce the usually mild pulling force required. With the
extraluminal stents described herein, the ductus is neither
compressed nor stretched (forcibly dilated, forcibly distended) but
held to its normal quiescent or diastolic outer diameter to expand
with the pulse or to allow peristaltic contraction within.
[0997] A permanent elastic polyester or polyether-polyurea
copolymeric (spandex, Elastane.RTM., Lycra.RTM., etc.) jacket can
also be applied to prevent the growth in an incipient aneurysm; in
this case, however, the jacket is secured in place by means
described below in the section entitled Jacket End-ties and
Side-straps, without ferromagnetic implants introduced into the
arterial wall. In treating an artery with negative remodeling,
stenosis which prompts stenting that includes a reduction in outer
diameter, as a precaution, some miniballs or portions thereof will
usually include antiproliferative or antirestenotic medication
and/or a radioisotope as well as encapsulated nonabsorbable
ferromagnetic content (usually superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder) used to draw the
ductus wall out to the stent-jacket. Situated entirely outside the
lumen, an extraluminal stent used to treat atheromatous tissue is
not subject to in-stent restenosis, so that antiproliferative
medication can be reduced if not eliminated.
[0998] By contrast, endoluminal stents that do not release
antiproliferative medication tend to become clogged through
in-stent restenosis, even though the antiproliferative elutants
themselves or their polymeric platforms can induce vasospasm (see,
for example, Watanabe, K., Nakamura, N. Kikuta, K., Matsubara, J.,
Okuyama E., and Katayama, T. 2010. "A Case of Newly Demonstrated
Coronary Spasm 4 Months after Paclitaxel-eluting Stent Implantation
for In-stent Restenosis," Journal of Cardiology Cases 1(1):
e33-e36; Tomassini, F., Varbella, F., Gagnor, A , Infantino, V.,
Luceri, S., and Conte, M. R. 2009. "Severe Multivessel Coronary
Spasm after Sirolimus-eluting Stent Implantation," Journal of
Cardiovascular Medicine 10(6):485-488; Lee, T. K., Lee, H. C.,
Hwang, K. W., Chun, K. J., Hong, T. J., and Shin, Y. W. 2008. "A
Case of Late Recurrent Vasospasm after Sirolimus-eluting Stent
Implantation," Korean Circulation Journal 38(3):174-178).
[0999] 8a. Basic Strengths and Weaknesses of Prior Art Stenting in
Vascular, Tracheobronchial, Gastrointestinal, and Urological
Interventions
[1000] To prevent dislodgement, or migration, an endoluminal stent
must exert circumferentially outward force. Whether in an artery or
different structure, it acts as a chronic local restraint upon the
ability of the substrate segment to adjust in gauge. Unless it is
absorbable, this restraint will persist, whether the stent becomes
endothelialized and incorporated into the lumen wall or not. That
the artery can adapt by remodeling does not equate to a normal end
condition. Moreover, often more than a single stent must be placed.
Endoluminal stenting is less adaptable than is extraluminal
stenting to the ductus and its condition. This results in a
uniformity and simplicity that comes with the lack of an option
selection process pertaining to the kind of stent and means of
insertion to be used.
[1001] All but ureteral endoluminal stents are structurally alike
and placed with a balloon in the same manner, reducing the
learining curve.' However, this simplicity only reflects an
inability to tailor the stent to the actual condition. Whether
following a balloon angioplasty, to place a conventional or
endoluminal stent is in itself a one step procedure and requires
but one, not two entry points, which imposes less trauma than
alternative treatments to include placement of an extraluminal
stent. Metal stents used for single entry stenting, or stenting
without an angioplasty, compress and trap the plaque against the
lumen wall.
[1002] The stent then remains to pose a permanent risk of fracture,
migration, and other complications. An extraluminal stent- or
impasse-jacket can be made nonabsorbable or absorbable. Existing
absorbable stents lack sufficient strength and require an
antecedent angioplasty or atherectomy. When the time needed for any
implant described herein is limited, the implant is preferably
either absorbable or allowed to remain indefinitely. Placement when
recovery will necessitate a second invasive procedure is justified
when the reason for intervention warrants. The removal of an
extraluminal stent can be deferred until well after placement.
[1003] Unlike an endoluminal stent which must parectasically press
into the luminal wall exerting high circumferential stresses to
avoid migrating (dislodging, displacement) and is substantially
static rather than compliant with ductus expansion and contraction,
disrupting the physiology and potentially aiding the spread of
infection into the dutus wall, an extraluminal stent dynamically
expands and contracts with the ductus (see, for example, Moore, J.
E. Jr. "Biomechanical Issues in Endovascular Device Design,"
Journal of Endovascular Therapy 2009 16 Supplement 111-11; Bedoya,
J., Meyer, C. A., Timmins, L. H., Moreno, M. R., and Moore, J. E.
2006. "Effects of Stent Design Parameters on Normal Artery Wall
Mechanics," Journal of Biomechanical Engineering 128(5):757-765;
Cervera, J. J. B. 2006. Stent Design and Arterial Mechanics:
Parameterization Tools Using the Finite Element Method, Thesis,
Biomechanical Engineering, Texas Agriculture and Mining University;
Holzapfel, G. A., Stadler, M., and Gasser, T. C., 2005. "Changes in
the Mechanical Environment of Stenotic Arteries during Interaction
with Stents: Computational Assessment of Parametric Stent Designs,"
Journal of Biomechanical Engineering 127(1):166-180; Vernhet, H.,
Demaria, R., Perez-Martin, A., Juan, J. M., Oliva-Lauraire, M. C.,
Marty-Double, C., Senac, J. P., and Dauzat, M. 2003. "Wall
Mechanics of the Stented Rabbit Aorta: Long-term Study and
Correlation with Histological Findings," Journal of Endovascular
Therapy 10(3):577-584; Rolland, P. H., Charifi, A. B., Verrier, C.,
Bodard, H., Friggi, A., Piquet, P., Moulin, G., and Bartoli, J. M.
1999. "Hemodynamics and Wall Mechanics after Stent Placement in
Swine Iliac Arteries: Comparative Results from Six Stent Designs,"
Radiology 213(1):229-246).
[1004] This is typified by the fact that, an absorbable copolymer,
not magnesium, which lacks the mechanical properties essential for
dynamic performance, is used in a temporary extraluminal stent.
Outside the ductus, the extraluminal stent is less constrained in
diameter, and an absorbable stent or impasse-jacket can leave
behind nontoxic constitutents that would embolize if released into
the bloodstream. Not constantly washed over by blood, the period
pending dissolution can be longer, and ingredients can be
incorporated that will allow dissolution controlled from outside
the body. Magnesium in an absorbable extraluminal, as opposed to an
endoluminal stent (see, for example, Erbel, R., Di Mario, C.,
Bartunek, J., Bonnier, J., and 12 other authors 2007. "Temporary
Scaffolding of Coronary Arteries with Bioabsorbable Magnesium
Stents: A Prospective, Non-randomised Multicentre Trial," Lancet
369(9576): 1839-1840), lacks the pliancy, resilience, fatigue
endurance limit, nontoxically alloyed, the strength required, and
as an electromagnetic shielding material inconsistent with the
ability to warm the implant by induction heating.
[1005] A functional stent of magnesium basis would have to be
alloyed for resilience and embedded with encapsulated magnetized
rare earth (lanthanoid) for magnetic strength. Neither can an
absorbable stent be used to protect against plaques that are likely
to appear at a later date, as addressed in the section below
entitled Comparison of Extraluminal with Endoluminal, or
Conventional, Stenting. The small luminal calibers in the vascular
tree make any approach that removes a prosthesis from the lumen and
resituates it to the perivascular space superior. There are basic
physiological and medical advantages, first in the removal and then
in the resituation to a location outside the vessel that allows
more material to be used.
[1006] For example, even made with neodymium, currently the highest
energy product material available for a magnet, an endoluminal
stent must be too small to contain enough of the material to
generate the field strength required to attract blood borne
ferromagnetically susceptible drug carrier nanoparticles. Instead,
a powerful external magnet must be used to induce the field within
the body. An endoluminal stent also stands between the drug and the
lesion to be treated and attracts the drug to itself. Any
robustness in the stent from added thickness means that to preserve
a minimum luminal cross section, the stent must press more into the
lumen wall. Historically, endoluminal stents offered distinct
advantages over treatment that necessitated open exposure.
[1007] However, an extraluminal stent can usually be introduced
through a small incision. The superior efficacy of an extraluminal
magnetic stent that draws or releases drugs from the bloodstream or
the intravascular component of the stent, meaning miniballs or
stays, compared to a drug-eluting endoluminal stent is addressed
below in several sections, to include that entitled Miniball and
Ferrofluid-borne Particle-impassable Jackets, or Impasse-jackets.
An endoluminal stent promotes the need for revascularization, which
procedure it will also hinder. If magnetized, it draws a drug
carrier nanoparticle or ferrofluid-bound drug to itself, diverting
the drug from the lesion abluminal to (outside, beyond, behind)
it.
[1008] In marked contrast, an extraluminal stent or impasse-jacket
leaves the lumen free of any foreign object, and positioned outside
the ductus, usually an artery, can usually take whatever volume of
space is required to present the field strength necessary to
attract the ferrofluid through the endothelium and into the plaque
or other lesion to any depth within the lumen wall. Since it
generates as high gradient a field as necessary at the treatment
site, no external magnet is necessary to induce a high gradient
field in an endoluminal stent deep within the body. Once emplaced,
the patient thereafter appears as necessary for a ferrofluid
injection and is free to depart.
[1009] Occasional injury from balloon overinflation or a special
insertion device notwithstanding, placed transluminally,
conventional or endoluminal stents are prosthetic linings that
compared to open surgery, confer luminal patency and symptomatic
palliation with serious trauma rare. An endoluminal stent is more
easily introduced into any deep-lying vessel or ductus that is
connected to neighboring tissue that should be left intact or
closely surrounded by tissue such as skeletal muscle and has a
lumen large enough to admit it. Endoluminal stents are also more
widely applicable to veins, often too thinly walled and
inappositely located to be stented by the extraluminal means
described herein; however, larger veins may be treated thus, and
the endoluminal processes possible with angioplasty-capable
barrel-assemblies and radial projection catheters described herein
are applicable to veins.
[1010] Endoluminal stents make possible telemetric monitoring (see,
for example, Ferguson, J. E. and Redish, A. D. 2011. "Wireless
Communication with Implanted Medical Devices Using the Conductive
Properties of the Body," Expert Review of Medical Devices
8(4):427-433; Chow, E. Y., Chlebowski, A. L., Chakraborty, S.,
Chappell, W. J.,and Irazoqui, P. P. 2010. "Fully Wireless
Implantable Cardiovascular Pressure Monitor Integrated with a
Medical Stent," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Engineering 57(6):1487-1496). Telemetric
feedback from an extraluminal stent would originate from a vantage
point outside and out of contact with the blood or other luminal
contents. However, the pressure within the lumen is no less
measurable from outside the ductus. Not only can an extraluminal
stent concentrate a drug carrier nanoparticle-bound drug passing in
the circulation and draw the drug abaxially through the lumen wall
into the lesion, but magnetized miniballs, stays, magnet-jackets,
and impasse-jackets can also be used thus, and any of these can
also be coated with medication or radioactive.
[1011] When excessive periadventitial fat, tunneling, or a lack of
clearance that necessitates much dissection interferes with the
placement of an extraluminal jacket, the degree of urgency, the age
and the condition of the patient will determine whether the
superior function of an extraluminal stent over time should be
chosen over an endoluminal stent as more expedient. Lower in the
body, the femoral, popliteal, and tibial arteries are often
affected by vascular disease. Ensheathed amid muscle, these
necessitate dissection to encircle. For vessels and ducts that lack
circumvascular clearance and require dissection, a purely
transluminal approach, with or without the introduction of an
endoluminal stent, is preferable, adverse sequelae then less
likely. This admits of using a radial projection catheter with
side-looking syringe tool-inserts to inject lesions along the lumen
wall or a barrel-assembly to implant medication miniballs into
lesions within such ductus, but disallows the application of an
extraluminal stent.
[1012] As the pulse or peristaltic wave traverses the stent, the
noncompliant margins of the stent can `dig into` and otherwise
irritate the lumen wall (see, for example, Kim, S. M. and Park, S.
Y. 2006. "A Study on the Stent Expansion Behavior of the Human
Artery Based on Finite Element Analysis," Key Engineering Materials
326-328:747-750; Ballyk, P. D. 2006. "Intramural Stress Increases
Exponentially with Stent Diameter: A Stress Threshold for
Neointimal Hyperplasia," Journal of Vascular and Interventional
Radiology 17(7):1139-1145; Gunn, J., Arnold, N., Chan, K. H.,
Shepherd, L., Cumberland, D. C., and Crossman, D. C. 2002.
"Coronary Artery Stretch Versus Deep Injury in the Development of
In-stent Neointima," Heart 88(4):401-405; Taylor, A. J., Gorman, P.
D., Kenwood, B., Hudak, C., Tashko, G., and Virmani, R. 2001. "A
Comparison of Four Stent Designs on Arterial Injury, Cellular
Proliferation, Neointima Formation, and Arterial Dimensions in an
Experimental Porcine Model," Catheterization and Cardiovascular
Interventions 53(3):420-425).
[1013] Depending upon the specific condition, location, and
clearance available for placing an intrinsically magnetized thin
stainless stent-jacket, the arteries in the extremities, which
course through sheaths amid muscles, will be better served by an
extraluminal stent with a thinner intrinsically or
quasi-intrinsically magnetized stent-jacket, as described below in
the section entitled Types of Stent-jacket, than an endoluminal
stent. Patient age is a significant factor in deciding whether the
clear lumen and superior performance over time of the extraluminal
stent justifies surgical access. A lack of circumvascular clearance
would interfere with compliance of the stent-jacket to the movement
of the ductus, which is a key advantage in the use of an
extraluminal stent.
[1014] Rather than to compress the substrate ductus with inadequate
clearance, the stent-jacket serves precisely to prevent
compression. It can also be used to prevent rubbing by neightboring
tissue, prevent and seal a fistula, and protect against
strangulation by a vascular ring. Sufficient clearance assumes that
there is no encroachment upon a neighboring nerve or vein. The
types of stent-jacket, the shape and distribution of magnets when
used, and the compressibility of skeletal muscle even when flexed
mean that clearance should almost always be sufficient. The
extraluminal stenting of anomalous coronary arteries which course
or tunnel through the myocardium where it is bridged over by
myocardial tissue over a length greater than 20 millimeters, then
emerges onto the epicardium, is best accomplished without
dissection.
[1015] The tunneled segment tends not to be susceptible to
atherosclerosis but may be to spasm (references cited below in the
section entitled Considerations as to Access). Patch-magnets on the
pericardium can serve to attract miniballs placed in the anterior
(ventral) wall of the artery. Inserting stays requires dissection
sufficient to expose the outer surface of the artery. If the age of
the patient and spasmodic or stenotic condition justify it, the
artery is shallow and relatively simple to free, and clearance can
be created for a stent-jacket, then a tunneling coronary artery
should be considered for dissecting free. Means exist to locate the
artery (see Kikuchi, K., Makuuchi, H., Murakami, H., Suzuki, T.,
Oono, M., and Chiba, K. 2006. "Use of an Audible Ultrasonic
Flowmeter to Locate Deeply Buried Coronary Arteries for Off-pump
Coronary Artery Bypass Grafting.," Japanese Journal of Thoracic and
Cardiovascular Surgery 54(2):75-77).
[1016] Use of the magnetic stenting to be described, which
necessitates the implantation of ferromagnetic miniballs or stays
within the wall of the ductus also necessitate that the ductus wall
have a at least minimal thickness and strength, for which testing
methods are addressed below in the section entitled Testing and
Tests. An endoluminal stent can be used despite delamination (tunic
avulsion) without leakage or a moderate degree of malacia in the
wall of a blood vessel, although this is less of a concern in the
trachea, for example. Whereas modern endoprostheses and stents are
made of materials such as titanium and polymers that are
nonferromagnetic or are at most weakly ferromagnetic as not to
disallow the use of magnetic resonance imaging (MRI), the present
means inherently demand the use of ferromagnetic materials that
once applied disallow the use of magnetic resonance imaging when
heating the implants is contraindicated.
[1017] However, where appropriate, the nonintrusive heating of the
implants has considerable potential to accelerate the release and
uptake of drugs, subject diseased tissue to cytotoxic temperatures
as a deliberate means of interstitial magnetic hyperthermic
therapy, denature coatings, such as solid protein solders,
accelerate the initial setting time of surgical adhesives, and has
other applications. While able to reduce restenosis, drug-eluting
stents remain susceptible to thrombosis and impaired
re-endothelialization (Inoue, T., Croce, K., Morooka, T., Sakuma,
M., Node, K., and Simon, D. I. 2011. "Vascular Inflammation and
Repair: Implications for Re-endothelialization, Restenosis, and
Stent Thrombosis," Journal of the American College of Cardiology.
Cardiovasc Interventions 4(10):1057-1066; Pilgrim, T. and
Windecker, S. 2009. "Drug-eluting Stent Thrombosis," Minerva
Cardioangiologica 57(5):611-620; Gupta, S. and Gupta, M. M. 2008.
"Stent Thrombosis," Journal of the Association of Physicians of
India 56:969-979; Garg, P. and Mauri, L. 2007. "The Conundrum of
Late and Very Late Stent Thrombosis Following Drug-eluting Stent
Implantation," Current Opinion in Cardiology 22(6):565-571;
Kawaguchi, R., Angiolillo, D. J., Futamatsu, H., Suzuki, N., Bass,
T. A., and Costa, M. A. 2007. "Stent Thrombosis in the Era of Drug
Eluting Stents," Minerva Cardioangiologica 55(2):199-211; Daemen,
J., Wenaweser, P., Tsuchida, K., Abrecht, L., and 12 other authors,
2007. "Early and Late Coronary Stent Thrombosis of Sirolimus
(rapamycin)-eluting and Paclitaxel-eluting Stents in Routine
Clinical Practice: Data from a Large Two-institutional Cohort
Study," Lancet 369(9562):667-678; Urban P. and De Benedetti, E.
2007. "Thrombosis: The Last Frontier of Coronary Stenting? [Comment
on Daemen et al., preceding]" Lancet 369(9562):619-621); Iakovou,
I., Schmidt, T, Bonizzoni, E., Ge, L., and 12 other authors,
A.2005. "Incidence, Predictors, and Outcome of Thrombosis After
Successful Implantation of Drug-eluting Stents," Journal of the
American Medical Association 293(17): 2126-2130).
[1018] More recent literature brings into question the sustained
efficacy of drug eluting stents on several grounds (see, for
example, Tung, R., Kaul, S., Diamond, G. A., and Shah, P. K. 2006.
"Narrative Review: Drug-eluting Stents for the Management of
Restenosis: A Critical Appraisal of the Evidence," Annals of
Internal Medicine 144(12):913-919). Any endoluminal stent remains
within the vessel where it can prompt thrombosis at any time
following insertion (see, for example, Kaul, S., Shah, P. K., and
Diamond, G. A. 2007. "As Time Goes By: Current Status and Future
Directions in the Controversy over Stenting," Journal of the
American College of Cardiology 50(2):128-137). Such a consequence
may not appear for years. While rare, this proves fatal in one
third of cases (http://www.ptca.org/des.html). Protection against
late thrombosis necessitates the long-term administration of
antiplatelet medication, which can induce an allergic reaction or
gastrointestinal erosion (gastritis, ulcer) and create a bleeding
problem.
[1019] By contrast, the implants to be described herein are not
contained within the lumen, are not exposed to and not in contact
with the blood flowing past, are incapable of movement relative to
the ductus wall, and so cannot be thrombogenic, rub, or dislodge.
Once placed, an endoluminal stent in a coronary artery and the
supportive medication it requires complicates surgery any surgery
to follow (see, for example, Wijeysundera, D. N., Wijeysundera, H.
C., Yun, L., Wasowicz, M., Beattie, W. S., Velianou, J. L., and Ko,
D. T. 2012. "Risk of Elective Major Noncardiac Surgery after
Coronary Stent Insertion: A Population-based Study," Circulation
126(11):1355-1362; Dweck, M. R. and Cruden, N. L. 2012. "Noncardiac
Surgery in Patients with Coronary Artery Stents," Archives of
Internal Medicine 172(14):1054-1055; Gupta, A. D., Streiff, M.,
Resar, J., and Schoenberg, M. 2012. "Coronary Stent Management in
Elective Genitourinary Surgery," British Journal of Urology
International 110(4):480-484; Gandhi, N. K., Abdel-Karim, A. R.,
Banerjee, S., and Brilakis, E. S. 2011. "Frequency and Risk of
Noncardiac Surgery after Drug-eluting Stent Implantation,"
Catheterization and Cardiovascular Interventions 77(7):972-976;
Albaladejo, P., Marret, E., Samama, C. M., Collet, J. P., Abhay,
K., and 6 others 2011. "Non-cardiac Surgery in Patients with
Coronary Stents: The RECO Study," Heart 97(19):1566-1572;
Savonitto, S., Caracciolo, M., Cattaneo, M., and De Servi, S. 2011.
"Management of Patients with Recently Implanted Coronary Stents on
Dual Antiplatelet Therapy Who Need to Undergo Major Surgery,"
Journal of Thrombosis and Haemostasis 9(11):2133-2142; Sonobe, M.,
Sato, T., Chen, F., Fujinaga, T., Shoji, T., Sakai, H., and 4
others 2011. "Management of Patients with Coronary Stents in
Elective Thoracic Surgery," General Thoracic and Cardiovascular
Surgery 59(7):477-482; Berger, P. B., Kleiman, N. S., Pencina, M.
J., Hsieh, W. H., and 6 others 2010. "Frequency of Major Noncardiac
Surgery and Subsequent Adverse Events in the Year after
Drug-eluting Stent Placement Results from the EVENT (Evaluation of
Drug-Eluting Stents and Ischemic Events) Registry," Journal of the
American College of Cardiology. Cardiovascular Interventions
3(9):920-927; Cruden, N. L., Harding, S. A., Flapan, A. D., Graham,
C., Wild, S. H., Slack, R., Pell, J. P., and Newby, D. E. 2010.
"Previous Coronary Stent Implantation and Cardiac Events in
Patients Undergoing Noncardiac Surgery," Catheterization and
Cardiovascular Interventions 3(3):236-242; Savonitto, S., D'Urbano,
M., Caracciolo, M., Barlocco F., and 4 others 2010. "Urgent Surgery
in Patients with a Recently Implanted Coronary Drug-eluting Stent:
A Phase II Study of `Bridging` Antiplatelet Therapy with Tirofiban
during Temporary Withdrawal of Clopidogrel," British Journal of
Anaesthesia 104(3):285-291; Schouten, O., Bax, J. J., and
Poldermans, D. 2007. "Management of Patients with Cardiac Stents
Undergoing Noncardiac Surgery," Current Opinion in Anaesthesiology
20(3):274-278; Brilakis, E. S., Banerjee, S., and Berger, P. B.
2007. "The Risk of Drug-eluting Stent Thrombosis with Noncardiac
Surgery," Current Cardiology Reports 9(5):406-411).
[1020] The use of a stent, necessarily oversized and substantially
noncompliant, inside an artery presumes a narrowing of the lumen as
the result of negative remodeling, and in most instances, an
antecedent angioplasty or atherectomy to have reduced that stenosis
(constriction, narrowing). Alternatively, a stent may be placed to
avert abrupt flap thrombosis and/or spasmodic closure. A healthy
artery that has not been angioplastied much less balloon injured
appears able to adapt to an oversized endoluminal stent (Dirsch,
O., Dahmen, U., Fan, L. M., Gu, Y. L., Shen, K., Wieneke, H., and
Erbel, R. 2004. "Media Remodeling--The Result of Stent Induced
Media Necrosis and Repair," Vasa 33(3):125-129). While
complication-free insertion of an endoluminal stent is routinely
less traumatic than is the placement of an extraluminal stent, an
endoluminal stent must be fixed in position by exerting outward
force against the surrounding wall of the ductus, which ipso facto
will have been diseased and usually angioplastied.
[1021] In an extraluminal stent, the lumen wall is drawn against
the internal surface of the stent-jacket, which prevents a
dissection or rupture. Drug-eluting stents reduce the need for
reintervention but have not demonstrated a long-term reduction in
subsequent myocardial infarction or death (Steinberg, D. H. and
Satler, L. F. 2008. "Drug-eluting Stent Thrombosis," Minerva
Cardioangiologica 56(1):127-137; Chen, J. P. 2008. "Safety and
Efficacy of the Drug-eluting Stent: A Double-edged Sword?,"
Southern Medical Journal 101(2):174-178; 123-124; Jaffe, R. and
Strauss, B. H. 2007. "Late and Very Late Thrombosis of Drug-eluting
Stents: Evolving Concepts and Perspectives," Journal of the
American College of Cardiology 50(2):119-127; Valimigli, M. 2006.
High-Risk Percutaneous Intervention in the Drug-Eluting Stent Era,
Doctoral Dissertation, Erasmus University, Rotterdam, Holland).
[1022] Drug eluting stents, notably those that deliver sirolimus
(rapamycin, Rapamune.RTM.), have also been reported to fracture and
become partially if not fully occluded (see, for example, Canan, T.
and Lee, M. S. 2010. "Drug-eluting Stent Fracture: Incidence,
Contributing Factors, and Clinical Implications," Catheterization
and Cardiovascular Interventions 75(2):237-245; Chhatriwalla, A.
K., Cam, A., Unzek, S., Bhatt, D. L., and 6 others 2009.
"Drug-eluting Stent Fracture and Acute Coronary Syndrome,"
Cardiovascular Revascularization Medicine 10(3):166-171; Jin, X.,
Zhang, S., Xie, H., Wang, C., Fan, Z., Zeng, Y., Shen, Z., and
Fang, Q. 2007. "Strut Fracture of DES: An Increasing Problem?,"
International Journal of Cardiology 118(2):e54-e56; Kim, E. J.,
Rha, S. W., Wani, S. P., Suh, S. Y., Choi, C. U., Kim, J. W., Park,
C. G., Seo, H. S., and Oh, D. J. 2007. "Coronary Stent Fracture and
Restenosis in the Drug-eluting Stent Era: Do We Have Clues of
Management?," International Journal of Cardiology 120(3):417-419;
Lee, M. S., Jurewitz, D., Aragon, J., Forrester, J., Makkar, R. R.,
and Kar, S. 2007. "Stent Fracture Associated with Drug-eluting
Stents: Clinical Characteristics and Implications," Catheterization
and Cardiovascular Interventions 69(3): 387-394).
[1023] Drug-eluting stents also appear to lead to a weakening of
the arterial wall that can result in an aneurysm (see, for example,
Luthra, S., Tatoulis, J., and Warren, R. J. 2007. "Drug-eluting
Stent-induced Left Anterior Descending Coronary Artery Aneurysm:
Repair by Pericardial Patch--Where Are We Headed?," Annals of
Thoracic Surgery 83(4):1530-1532; Panja, M., Basu, S., and Mondol,
S. 2005 "A Case of Giant Aneurysm Following Percutaneous Coronary
Intervention," Indian Heart Journal 7(6):731-733). Endoluminal
stents containing nonferrous metals, drug-eluting or not, can
elicit a severe allergic reaction (see Almpanis, G. C., Tsigkas, G.
G., Koutsojannis, C., Mazarakis, A., Kounis, G. N., and Kounis, N.
G. 2010. "Nickel Allergy, Kounis Syndrome and Intracardiac Metal
Devices," International Journal of Cardiology 145(2):364-365), and
in association with allergic inflammatory reactions, drug-eluting
stents can induce thrombosis (Virmani, R, Guagliumi, G., Farb, A.,
Musumeci, G., Grieco, N., Motta, T., Mihalcsik, L., Tespili, M.,
Valsecchi, O., and Kolodgie, F. D. 2004. "Localized
Hypersensitivity and Late Coronary Thrombosis Secondary to a
Sirolimus-Eluting Stent: Should We Be Cautious?," Circulation
109(6):701-705. The action associated with the placement of a
conventional endoluminal stent can produce the conditions that
result in restenosis (see, for example, Anderson, H. V. and
Carabello, B. A. 2000. "Provisional versus Routine Stenting:
Routine Stenting is Here to Stay," Circulation 102(24):2910-2914),
and once placed, the stent that was required for sequelae which
were the direct result of balloon angioplasty is not just
susceptible to but becomes itself an additional factor that
provokes restenosis.
[1024] By comparison, a stent with no endoluminal presence cannot
clog, much less stimulate a response that would clog it. In order
to minimize the risk of migration whenever the artery expands, an
endoluminal stent must exceed the lumen in its expanded diameter.
In the gastrointestinal tract, a ureter, or gamete duct, the stent
must exceed the resting diameter, thus interfering with
peristalsis. Endoluminal stents for use in the gastrointestinal
tract will usually have pronounted prominences about the
circumference to avert migration by peristalsis. Not allowing
either an artery or the gut to contract, an endoluminal stent
remains as a chronic source of noncompliance or nonadaptive
restraint and irritation.
[1025] If temporary (absorbable), the rate of dissolution is not
likely to match that required, even when this period can be
predicted. Moreover, if underexpanded in an artery, sub-acute
thrombosis can develop in the gaps that separate the stent from the
vessel wall. In contrast, an extraluminal stent-jacket, is pliable
and matched in diameter to the resting diameter of the substrate
ductus. It then expands and contracts along with the pulse and
frees the gut to contract inside it. At least in the carotid
arteries, the disruption of forced distention imposed by an
endoluminal stent appears to subside during the first few weeks
following placement, vessels suited to higher pressures apparently
able to adapt (see, for example, Dirsch et al. 2004, cited
above).
[1026] Adapted to or not, the widened diameter of the lumen and
resistance to migration imparted by overexpansion (see, for
example, Rogers, C., Tseng, D. Y., Squire, J. C., and Edelman, E.
R. 1999. "Balloon-Artery Interactions During Stent Placement: A
Finite Element Analysis Approach to Pressure, Compliance, and Stent
Design as Contributors to Vascular Injury," Circulation Research
84(4):378-83) do little to reduce thrombosis and restenosis (Lally,
C., Dolan, F., and Prendergast, P. J. 2004. "Cardiovascular Stent
Design and Vessel Stresses: A Finite Element Analysis," Journal of
Biomechanics 38(8):1574-1581; Rogers, C. and Edelman, E. R. 1995.
"Endovascular Stent Design Dictates Experimental Restenosis and
Thrombosis," Circulation 91(12):2995-3001; Gunn, J., Arnold, N.,
Chan, K. H., Shepherd, L., Cumberland, D. C., and Crossman, D. C.
2002, cited in the preceding paragraph).
[1027] Furthermore, the clinical results seen in the coronary
arteries may differ markedly from those obtained with peripheral
arteries (see, for example, Dube, H., Clifford, A. G., Barry, C.
M., Schwarten, D. E., and Schwartz, L. B. 2007. "Comparison of the
Vascular Responses to Balloon-Expandable Stenting in the Coronary
and Peripheral Circulations: Long-term Results in an Animal Model
Using the TriMaxx Stent," Journal of Vascular Surgery
45(4):821-827; Krueger, K. D., Mitra, A. K., DelCore, M. G.,
Hunter, W. J. 3rd, and Agrawal, D. K. 2006. "A Comparison of
Stent-induced Stenosis in Coronary and Peripheral Arteries,"
Journal of Clinical Pathology 59(6):575-579, which agree as to
there being differences but contradict one another as to whether
the severity is greater in peripheral than in coronary
arteries).
[1028] In the vasculature, chronic contact with the luminal
endothelium probably excites the subjacent layers to
proliferate--"It is believed that the central role of the vascular
endothelium is to maintain quiescence of the underlying media and
adventitia" (Aoki, J., Serruys, P. W., van Beusekom, H., Ong, A.
T., McFadden, E. P., Sianos, G., van der Giessen, W. J., Regar, E.,
de Feyter, P. J., Davis, H. R., Rowland, S., and Kutryk, M. J.
2005. "Endothelial Progenitor Cell Capture by Stents Coated with
Antibody Against CD34: The HEALING-FIM (Healthy Endothelial
Accelerated Lining Inhibits Neointimal Growth-First In Man)
Registry," Journal of the American College of Cardiology
45(10):1574-1579).
[1029] Whether in the vascular tree, the tracheobronchial tree, the
bile, or urinogenital ducts, endoluminal stents cover over and
compress portions of the internal surface or endothelium of the
lumen, necessarily interfering with normal lumen wall physiology at
every level from the biochemical, to the microscopic, to the gross
anatomical. The portions of the lumen wall in contact with the
stent are blocked off from the normal chemical and physiological
environment at the same time that the portions of the stent in
contact with the contents flowing through serve as a platform for
the deposition of occlusive matter, whether salts in the ureters or
platelets and fat in the bloodstream.
[1030] An endoluminal stent forcibly interferes with normal
vasomotion, and to this, a drug-eluting stent can add chemical
interference (see, for example, Tomassini, F., Varbella, F.,
Gagnor, A., Infantino, V., Luceri, S., and Conte, M. R. 2009.
"Severe Multivessel Coronary Spasm after Sirolimus-eluting Stent
Implantation," Journal of Cardiovascular Medicine 10(6):485-488;
Brott, B. C., Anayiotos, A. S., Chapman, G. D., Anderson, P. G.,
and Hillegass, W. B. 2006. "Severe, Diffuse Coronary Artery Spasm
after Drug-eluting Stent Placement," Journal of Invasive Cardiology
18(12):584-592; Hamilos, M., Sarma, J., Ostojic, M., Cuisset, T.,
Sarno, G., and 9 others 2008. "Interference of Drug-eluting Stents
with Endothelium-dependent Coronary Vasomotion: Evidence for
Device-specific Responses," Circulation. Cardiovascular
Interventions 2008 1(3):193-200; El-Bialy, A., Shenoda, M., and
Caraang, C. 2006. "Refractory Coronary Vasospasm Following
Drug-eluting Stent Placement Treated with Cyproheptadine," Journal
of Invasive Cardiology 18(2):E95-98). Endoluminal stents also pose
a risk of late thrombosis that necessitates the long term
administration of platelet blockade medication.
[1031] Endoluminal stents placed to treat vasospastic angina may
induce or displace spasm at the margins (see, for example, Kaku,
B., Honin, K., Horita,Y., Uno, Y., Yamazaki, T., Funada, A., and
Ohka, T. 2005. "The Incidence of Stent-edge Spasm after Stent
Implantation in Patients with or without Vasospastic Angina
Pectoris," International Heart Journal 46(1):23-33; Celik, T.,
Iyisoy, A., Yuksel, U. ., Bugan, B., and Ersoy, I. 2009.
"Stent-edge Vasospasm after Bare Metal Stent Implantation: A Case
Report and Review of the Literature," Gulhane Tip Dergisi
51:174-176). Unlike an extraluminal stent with the aid of suitable
medication such as nicorandil, trihexyphenidyl hydrochloride, or
denopamine., an endoluminal stent is susceptible to deformation
from severe spasm (Yoshida, T., Kobayashi, Y., Nakayama, T.,
Kuroda, N., Komiyama, N., and Komuro, I. 2006. "Stent Deformity
Caused by Coronary Artery Spasm," Circulation Journal
70(6):800-801). Neither would an extraluminal stent be likely to
induce thrombosis or spasm as have drug-eluting endoluminal stents
(Brott, B. C., Anayiotos, A. S., Chapman, G. D., Anderson, P. G.,
and Hillegass, W. B. 2006. "Severe, Diffuse coronary Artery Spasm
after Drug-eluting Stent Placement," Journal of Invasive Cardiology
18(12):584-592).
[1032] In the airway, contact of the lumen wall with the stent
blocks out oxygenated air abaxially (inward through the
endothelium), secretion adaxially (outward from the endothelium
onto the internal surface of the lumen), as well as transport along
the lumen wall. Similarly, a stent in the vasculature obliterates
the two-way blood-endothelial interface, resulting in long term
endothelial dysfunction (see, for example, Celik et al. 2009 op
cit.; Caramori, P. R., Lima, V. C., Seidelin, P. H., Newton, G. E.,
Parker, J. D., and Adelman, A. G. 1999. "Long-term Endothelial
Dysfunction after Coronary Artery Stenting," Journal of the
American College of Cardiology 34(6): 1675-1679;). Endothelial
secretory dysfunction is a significant factor in much vascular
pathology.
[1033] Where endothelial dysfunction exits due to an antecedent
acute cardiac event, an endoluminal stent is likely to add further
to the dysfunction (Akcakoyun, M., Kargin, R., Tanalp, A. C., Pala,
S., Ozveren, O., Akcay, M., Barutcu, I., and Kirma, C. 2008.
"Predictive Value of Noninvasively Determined Endothelial
Dysfunction for Long-term Cardiovascular Events and Restenosis in
Patients Undergoing Coronary Stent Implantation: A Prospective
Study," Coronary Artery Disease 19(5):337-343). Broadly, a
mechanical expedient essential to meet the priimary requirement of
maintaining patency, endoluminal stents are otherwise noncompliant
with and disruptive of ductus physiology in every way.
[1034] In the airway, secretory and mucociliary (mucociliary
`escalator`) action, the action of alveolar macrophages and tissue
histiocytes, normal exposure to oxygen and moisture, other chemical
interaction at the surface of the lumen such as the local secretion
of immunoglobulins (The Merck Manual of Diagnosis and Therapy, 18th
Edition, page 1387), and smooth muscle action are all disrupted.
Interference with the normal physiology of the tracheobronchial
tree can exert a significant nonmechanical secondary effect in
impairing immunomodulatory function. The thicker walls along the
gastrointestinal tract accommodate ductus-intramural implants
without the need for tumefacients, for example.
[1035] Whether in the vascular or bronchial tree, the minimum
caliber of a ductus tractable to the placement of an extraluminal
stent primarily depends upon the ability of the ductus wall to
accept and retain the implants and secondarily upon the
availability of a barrel-assembly or stay insertion tool small
enough to accomplish implantation. Wall insufficiency will
generally precede the inability to produce a muzzle-head small that
is enough to fit. In the bronchial tree, the tertiary bronchi,
which must adapt in gauge necessitating smooth muscle, usually
represent this limit. An extraluminal stent that leaves the lumen
clear avoids the restriction to smooth muscle action, blockage to
secretion, and functioning of the mucociliary escalator. The
vasospasm of asthma affects the bronchioles at the junction with
the alveoli where the size and distribution of the tissue affected
rule out treatment by means other than the use of drugs.
[1036] Stenting has, however, been used to treat asthma comorbidity
(see, for example, Ernst, A., Majid, A., Feller-Kopman, D.,
Guerrero, J., Boiselle, P., and 6 others, 2007. "Airway
Stabilization with Silicone Stents for Treating Adult
Tracheobronchomalacia: A Prospective Observational Study," Chest
132(2):609-616). Endoluminal stents in the airway often cause
chronic irritation and are subject to fracture (Mittleman, E.,
Weisse, C., Mehler, S. J., and Lee, J. A. 2004. "Fracture of an
Endoluminal Nitinol Stent Used in the Treatment of Tracheal
Collapse in a Dog," Journal of the American Veterinary Medical
Association 225(8): 1196, 1217-1221; Woo, H. M., Kim, M. J., Lee,
S. G., Nam, H. S., Kwak, H. H., Lee, J. S., Park, I. C., and Hyun,
C. 2007. "Intraluminal Tracheal Stent Fracture in a Yorkshire
Terrier," Canadian Veterinary Journal 48(10):1063-1066) and some
types are liable to migrate (see, for example, Noppen, M., Meysman,
M., Claes, I., D'Haese, J., and Vincken, W. 1999. "Screw-thread vs
Dumon Endoprosthesis in the Management of Tracheal Stenosis," Chest
115(2):532-535; Kitanosono, T., Honda, M., Matsui, S., Hashimoto,
T., Munechika, H., Hishida, T., Okubo, K., and Koizumi, K. 1997.
"Migration of Gianturco Expandable Metallic Stents in the Upper
Trachea," Cardiovascular and Interventional Radiology
20(3):216-218).
[1037] In the trachea or bronchi, much less the gut, a conventional
stent, in contrast to subfibrosally implanted minispheres or stays,
which are substantially isolated from the lumen and its contents,
can serve as a scaffold for the spread of infection to include
tubercular (Casal, R. F. 2010. "Update in Airway Stents," Current
Opinionin Pulmonary Medicine 16(4):321-328; Agrafiotis, M.,
Siempos, I. I., and Falagas, M. E. 2009. "Infections Related to
Airway Stenting: A Systematic Review," Respiration 78(1):69-74;
Park, K. Y. and Park, C. H. 2005. "Candida Infection in a Stent
Inserted for Tracheal Stenosis after Heart Lung Transplantation,"
Annals of Thoracic Surgery 79(3):1054-1056; Bautista, M.,
Greenberg, A., and Weissman, P. 2002. "Expansion of a Lung Abscess
after Stent Closure of a Bronchoesophageal Fistula,"
Gastrointestinal Endoscopy 55(2):281-283).
[1038] In muscular arteries, the use of stays avoids the lumen
entirely, eliminating direct contact with the bloodstream as an
avenue for the systemic spread of infection (see, for example,
Chambers, C. E., Eisenhauer, M. D., McNicol, L. B., Block, P. C.,
Phillips, W. J., Dehmer, G. J., Heupler, F. A., and Blankenship, J.
C. 2006. "Infection Control Guidelines for the Cardiac
Catheterization Laboratory: Society Guidelines Revisited,"
Catheterization and Cardiovascular Interventions 67(1):78-86;
Ramsdale, D. R., Aziz, S., Newall, N., Palmer, N., and Jackson, M.
2004. "Bacteremia Following Complex Percutaneous Coronary
Intervention," Journal of Invasive Cardiology 16(11):632-634,
available at http://www.invasivecardiology.com/article/3330;
Culver, D. A., Chua, J., Rehm, S. J., Whitlow, P., and Hertzer, N.
R. 2002. "Arterial Infection and Staphylococcus Aureus Bacteremia
after Transfemoral Cannulation for Percutaneous Carotid Angioplasty
and Stenting," Journal of Vascular Surgery 35(3):576-579; Munoz,
P., Blanco, J. R., Rodriguez-Creixems, M., Garcia, E., Delcan, J.
L., and Bouza, E. 2001. "Blood Stream Infections after Invasive
Nonsurgical Cardiology Procedures," Archives of Internal Medicine
161(17):2110-2115; Samore, M. H., Wessolossky, M. A., Lewis, S. M.,
Shubrooks, S. J. Jr., and Karchmer, A. W. 1997. "Frequency, Risk
Factors, and Outcome for Bacteremia after Percutaneous Transluminal
Coronary Angioplasty," American Journal of Cardiology
79(7):873-877; Shea, K. W., Schwartz, R. K., Gambino, A. T., Marzo,
K. P., and Cunha, B. A. 1995. "Bacteremia Associated with
Percutaneous Transluminal Coronary Angioplasty," Catheterization
and Cardiovascular Diagnosis 36(1):5-10).
[1039] In any lumen, an endoluminal stent accumulates debris and
pathogens, increasing the risk of infection, local and spreading.
Esophageal stents have been suspected to spread infection to the
spine (see, for example, Mullen, T. D., Sharma, A. K., and Varma,
A. K. 2012. "Cervical Osteomyelitis after Placement of a
Self-expanding Plastic Stent for Palliation of Dysphagia Associated
with Chemoradiation-induced Esophageal Strictures," Head and Neck
in press February 2012; Li, C. Y., Chen, W. C., Yang, S. H., and
Lee, Y. C. 2009. "A Rare Complication of Esophageal Stent: Spinal
Epidural Abscess," Annals of Thoracic Surgery 88(5):1700-1702Lloyd,
D. and Smith, D. 2002. "Cervical Discitis in a Patient with an
Oesophageal Stent for Carcinoma," Rheumatology 41(12): 1453,
although the spread of infection to the meninges can occur
following a spontaneous perforation of the esophagus (Boerhaave's
syndrome) (Jurani, C. C., Early, G. L., and Roberts, S. R. 2002.
"Spontaneous Esophageal Perforation Presenting as Meningitis,"
Annals of Thoracic Surgery 3(4):1294-1296), and may be promoted by
poststenting chemoradiation (Christie, N. A., Buenaventura, P. O.,
Fernando, H. C., Nguyen, N. T., Weigel, T. L., Ferson, P. F., and
Luketich, J. D. 2001. "Results of Expandable Metal Stents for
Malignant Esophageal Obstruction in 100 Patients: Short-term and
Long-term Follow-up," Annals of Thoracic Surgery
71(6):1797-1802).
[1040] The risk of migration that necessitates a large diameter
with outward radial force to disrupt function and assist in
inoculating the ductus wall should the stent become infected is
primarily the result of the propulsive or propagative action of the
contents passed. Mass flow through the stent undiminished, even
when expanded just enough to preclude migration, an endoluminal
stent interrupts and thus interferes with the radial movements in
the ductus wall beginning at both the proximal and distal stent
margins. In the vascular tree and ureters, the endoluminal stent
acts as a scaffold for the deposition of matter out of the passing
fluid. In a ureter, urinary salts accrete on the stent, which to
prevent total occlusion must be replaced every few months.
[1041] In the vascular tree, an endoluminal stent disrupts laminar
or streamline flow, the turbulence predisposing to thrombus
formation and rarely, infection (see, for example, Gonda, E.,
Edmundson, A., and Mann, T. 2007. "Late Coronary Stent Infection: A
Unique Complication after Drug-eluting Stent Implantation," Journal
of Invasive Cardiology 19(10):E307-E308 Kaufmann, B. A., Kaiser,
C., Pfisterer, M. E., and Bonetti, P. O. 2005. "Coronary Stent
Infection: A Rare but Severe Complication of Percutaneous Coronary
Intervention," Swiss Medical Weekly 135(33-34):483-487; Chambers,
S. T. 2005. "Diagnosis and Management of Staphylococcal Infections
of Vascular Grafts and Stents," Internal Medicine Journal 35
Supplement 2:S72-S78; Dieter, R. S. 2000. "Coronary Artery Stent
Infection," Clinical Cardiology 23(11):808-810; Latham, J. A. and
Irvine, A. 1999. "Infection of Endovascular Stents: An Uncommon but
Important Complication," Cardiovascular Surgery 7(2):179-182;
Deiparine, M. K., Ballard, J. L., Taylor, F. C., and Chase, D. R.
1996. "Endovascular Stent Infection," Journal of Vascular Surgery
23(3):529-533). An extraluminal stent avoids the foregoing
problems.
[1042] Additionally providing support from about the outer surface
and interposing a shield or physical barrier between the ductus and
surrounding tissue, an extraluminal stent interferes with the
spread of infection and reduces the risk of rupture as typified by
the carotid blowout syndrome (see, for example, Broomfield, S. J.,
Bruce, I. A., Luff, D. A., Birzgalis, A. R., and Ashleigh, R. J.
2006. "Endovascular Management of the Carotid Blowout Syndrome,"
Journal of Laryngology and Otology 120(8):694-697; Chaloupka, J.
C., Putman, C. M., Citardi, M. J., Ross, D. A., and Sasaki, C. T.
1996. Endovascular Therapy for the Carotid Blowout Syndrome in Head
and Neck Surgical Patients: Diagnostic and Managerial
Considerations," American Journal of Neuroradiology 17(5):843-852).
Moreover, as addressed below in the section entitled Radiation
Shield-jackets and Radiation Shielded Stent-jackets Absorbable and
Nonabsorbable, an extraluminal stent can provide radiation
shielding (see, for example, McDonald, M. W., Moore, M. G., and
Johnstone, P. A. 2012. "Risk of Carotid Blowout after Reirradiation
of the Head and Neck: A Systematic Review," International Journal
of Radiation Oncology Biology Physics 82(3):1083-1089). The impulse
to prevent migration by overly expanding a stent in particular can
result in chronic restraint-irritation and injury of the ductus
leading to delayed and long term sequelae.
[1043] More specifically, an endoluminal stent introduces wave
reflection sites at the stent entrance and exit (see, for example,
Alderson, H. and Zamir, M. 2004. "Effects of Stent Stiffness on
Local Haemodynamics with Particular Reference to Wave Reflections,"
Journal of Biomechanics 37(3):339-348; Seo, T., Schachter, L. G.,
and Barakat, A. I. 2005. "Computational Study of Fluid Mechanical
Disturbance Induced by Endovascular Stents," Annals of Biomedical
Engineering 33(4):444-456; Bedoya, J., Meyer, C. A., Timmins, L.
H., Moreno, M. R., and Moore, J. E. 2006. "Effects of Stent Design
Parameters on Normal Artery Wall Mechanics," Journal of
Biomechanical Engineering 128(5):757-765), centrifugally agitating
platelets and other blood cells that normally move axially in
laminar flow (see, for example, He, Y., Duraiswamy, N., Frank, A.
O., and Moore, J. E. Jr. 2005. "Blood Flow in Stented Arteries: A
Parametric Comparison of Strut Design Patterns in Three
Dimensions," Journal of Biomechanical Engineering 127(4):637-647;
Porth, C. M. 2004. Pathophysiology: Concepts of Altered Health
States, Philadelphia, Pa.: Lippincott Williams and Wilkins),
therewith inducing the thrombogenicity associated with turbulent
flow.
[1044] With a stent that lies entirely outside the lumen, the
lifelong use of a statin drug that results from this turbulence is
avoided. Essentially, an endoluminal stent not only obstructs,
occludes, irritates, and creates stenosis, but forces the
propulsive forces in the lumen wall to make the ductus injure
itself. Practically irrecoverable, endoluminal stents can be
life-saving upon insertion only to produce serious if not
life-threatening complications later. A stent within an artery,
especially one made of metal, encourages the clotting and adhesion
to its surface of blood, prompting the administration of platelet
blockade or anticoagulants to high levels conducive to bleeding
problems.
[1045] Except where an absorbable stent can be used (see, for
example, Erbel, R., Di Mario, C., Bartunek, J., Bonnier, J., and 12
other authors 2007. "Temporary Scaffolding of Coronary Arteries
with Bioabsorbable Magnesium Stents: A Prospective, Non-randomised
Multicentre Trial," Lancet 369(9576): 1839-1840), once placed, an
endoluminal stent is removed when it must but is then usually
replaced, prompting the administration of antiplatelet medication
on an extended if not lifelong basis. While configured unlike a
vascular stent but much longer in the form of a catheter, a
ureteric stent likewise encourages the deposition and accretion of
debris upon it, in this case, calcium oxalate, calcium phosphate,
and ammonium magnesium phosphate salts.
[1046] Situated thus, the contents, if not positively induced to
precipitate onto the foreign surface, can additionally be trapped
inside and clog the stent. Unlike endoureteral stents, an
extraureteral stent is not susceptible to encrustation, bacterial
colonization, clogging, or enstonement that necessitates
replacement every three months, which can be operatively difficult
if not painful. Except for those made of tantalum or platinum,
endoluminal stents are poorly radiopaque, and should one in the
arterial tree be dropped from the balloon (Hubner, P. J. B. 1998.
Guide to Coronary Angioplasty and Stenting, Amsterdam, Holland:
Harwood Academic Publishers, page 108), will usually prove
difficult if not impossible to locate much less retrieve without
open exploratory surgery. Historically, the main problem with
stenting in the vascular tree--restenosis--was to an extent
ameliorated with the appearance of the Palmaz-Schatz stent.
[1047] However, the central joint or articulation in this
endoluminal stent, which is provided to allow some flexion for
trackability, is a point of weakness that fails to adequately
retain the subjacent lumen wall, which under intraductal ultrasound
is seen to prolapse into the joint and constrict the lumen (see,
for example, Kim, S. W., Mintz, G. S., Ohlmann, P., Hassani, S. E.,
Fernandez, S., Lu, L., Chu, W. W., and 9 others 2006. "Frequency
and Severity of Plaque Prolapse within Cypher and Taxus Stents as
Determined by Sequential Intravascular Ultrasound Analysis,"
American Journal of Cardiology 98(9):1206-1211; Prendergast, P. J.,
Lally, C., Daly, S., Reid, A. J., Lee, T. C., Quinn, D., and Dolan,
F. 2003. "Analysis of Prolapse in Cardiovascular Stents: A
Constitutive Equation for Vascular Tissue and Finite-Element
Modelling," Journal of Biomechanical Engineering
125(5):692-699).
[1048] In fact, " . . . the stent has poor trackability and is best
used for proximal lesions in straight vessels, free from disease
down to the lesion," (Hubner, Op. cit., page 107). Such a
consequence also speaks to the advantage of plaque removal through
atherectomy rather than balloon crushing, with medical and not just
mechanically adverse consequences of the merely displaced plaque
addressed in the sections above entitled Drug-releasing and
Irradiating miniballs, Stays, and Ferrofluids, and Basic Strengths
and Weaknesses of Prior Art Stenting in Vascular, Tracheobronchial,
Gastrointestinal, and Urological Interventions, among others.
[1049] In the effort to suppress the restenosis of an endovascular
stent, an angiotensin converting enzyme inhibitor (angiotensin
receptor antagonist or blocker--see for example, Traub, Y. and
Shapiro, A. P. 1997, "Management of Hyertension with Particular
Attention to the Renin-Angiotensin System," in Glew, R. H. and
Ninomiya, Y., Clinical Studies in Medical Biochemistry, New York,
N.Y.: Oxford University Press), such as valsartan)(Diovan.RTM., an
angiotensin receptor blocker that acts as a cytokine gene
expression inhibitor, such as tacrolimus; or candesartan cilexetil;
or an angiotensin II receptor antagonist or blocker and cytostatic
immunosuppressant, such as sirolimus (rapamycin, Rapamune.RTM.) is
often administered, even though the efficacy in long term use of
immunosuppressants or anti-hypertensives for this purpose remains
unproven.
[1050] A more recent version of the Palmaz-Schatz stent, the
Palmaz-Schatz Crown stent, has two spiral articulations, and while
more trackable, still suffers from the common problems associated
with endoluminal vascular placement, as do the most advanced
endovascular stents. If the lumen is obstructed, some tend to drop
from the balloon. If the stent becomes stuck and an effort is made
to withdraw it, or if the balloon is withdrawn, single wire coil
stents may uncoil, and rarely, catheter components, to include
guidewires, Rotablator.RTM. Systems, and stents, become entrapped
during cardiologic interventions, causing life-threatening
complications and the need for emergency cardiac surgery (Alexiou,
K., Kappert, U., Knaut M., Matschke, K., and Tugtekin, S. M. 2006.
"Entrapped Coronary Catheter Remnants and Stents: Must They Be
Surgically Removed?," Texas Heart Institute Journal
33(2):139-142.
[1051] With several endovascular stents, the delivery catheter
balloon may fail to deflate, making withdrawal difficult. In some
instances, this has led to serious complications requiring coronary
artery bypass surgery or to death. One factor in the promotion of
intimal hyperplasia by an endoluminal stent is that it creates an
abrupt change in the internal diameter of the lumen (see, for
example, Adam, A., Dondelinger, R. F., and Mueller, P. R. (editors)
1997. Textbook of Metallic Stents, London, England: Informa
HealthCare, page 179). In any endoluminal stent, a larger mesh or
grid gap improves side branch accessibility to a guidewire, but
only at the risk of lumen wall prolapse due to a lack of support
(Hubner, op cit. page 114). Furthermore, situated at or beside the
ostium, the grid is more thrombogenic, making a large mesh risky
for spanning a side branch. Inducing patency by extraluminal means
will not eschew all limitations and sequelae, but it will
these.
[1052] The thrombogenic, spasm inducing, and narrowing that can
result from allowing a rare fractured guidewire to remain in a
coronary artery demand surgical removal (Demirsoy, E., Bodur, H.
A., Arbatli, H., Ya an, N., Yilmaz, O., Tukenmez, F., Ozturk, S.,
and Sonmez, B. 2005. "Surgical Removal of Fractured Guidewire with
Ministernotomy," (in English) Anatolian Journal of Cardiology
(Anadolu Kardiyoloji Dergisi) 5(2):145-147, also cited above).
Radially and longitudinally rigid and continuous in structure, most
endoluminal stents are noncompliant to physiological changes in
vascular gauge and unaccommodating of gross movement. Thus, to span
or straddle branches or to bend, separate stents must be used to
either side of the branch or point of flexion, presenting the
multiple thrombogenic edges, or margins, of two or more stents.
Even rimless, or uniform in gauge out to the edges, an endoluminal
stent compresses the tissue it restrains, creating inconsistencies
in lumen diameter and turbulent flow at either end.
[1053] The tendency for the edges of endovascular (endoluminal)
stents to irritate and induce the formation of thrombi is increased
with multiple stents, as when used to anchor the ends of an
endovascular graft (see Parodi, J. C., Veith, F. J., and Marin, M.
L. 1998. Endovascular Grafting Techniques, Baltimore, Md.: Williams
and Wilkins, page 128, figure 15.5), or in treating either
intermittent segments of vessels diseased over lengths considered
too small and not sufficiently deteriorated to justify excision and
anastomosis or the insertion of a graft, or segments to either side
of a branch or point of flexion. Largely dependent upon caliber,
that the margins of an endovascular stent are noncompliant both
inwardly and outwardly means that the stent will act as a factor in
its restenosis and then make the transluminal removal of the
blockage difficult.
[1054] Lacking a side-hole wherewith to straddle or span
T-junctions of which the orifices (ostia, entries) are notably
susceptible to atherogenesis, endoluminal stents necessitate the
use of two stents, thus leaving the segment of the vessel wall
opposite and subtended by the opening to the branch, or ostium,
unstented. Since the proximating ends of endoluminal stents to
either side of the branch opening usually maintain the diameter of
the lumen past the opening over the distance separating the two,
this usually is not problematic. Even then, however, placing
endoluminal stents to either side of a T-branch also results in the
presentation of four thrombogenic edges in positions of maximum
nonlaminar flow and shear stress favorable to the formation of
thrombi and lesions.
[1055] Furthermore, "evidence is emerging that the abrupt
compliance mismatch that exists at the junction between the stent
ends and the host arterial wall disturbs both the vascular
hemodynamics and the natural wall stress distribution" (Berry, J.
L., Manoach, E., Mekkaouri, C., Rolland, P. H., Moore, J. E., and
Rachev, A. 2002. "Hemodynamics and Wall Mechanics of a Compliance
Matching Stent: in Vitro and in Vivo Analysis," Journal of Vascular
and Interventional Radiology 13(1):97-105; for the effect of shear
stress on in-stent restenosis, see Wentzel, J. J., Krams, R.,
Schuurbiers, J. C. H.; Oomen, J. A. Kloet, J., van der Giessen, W.
J., Serruys, P. W., and Slager, C. J., 2001. "Relationship between
Neointimal Thickness and Shear Stress after Wallstent Implantation
in Human Coronary Arteries," Circulation 103(13):1740-1745 and
Sanmartin, M., Goicolea, J., Garcia, C., Garcia, J., Crespo, A.,
Rodriguez, J., and Goicolea, J. M. 2006. "Influencia de la tension
de cizallamiento en la reestenosis intra-stent: estudio in vivo con
reconstruccion 3D y dinamica de fluidos computacional," [Influence
of Shear Stress on in-Stent Restenosis: in Vivo Study Using 3D
Reconstruction and Computational Fluid Dynamics]," Revista espanola
de cardiologia (Spanish Journal of Cardiology) 59(1):20-27, in
Spanish with abstract in English at Pubmed).
[1056] Arteries that support a pronounced pulse are stated to adapt
to forced distention over time (see, for example, Dirsch, O.,
Dahmen, U., Fan, L. M., Gu, Y. L., Shen, K., Wieneke, H., and
Erbel, R. 2004. "Media Remodeling--The Result of Stent Induced
Media Necrosis and Repair," Vasa 33(3):125-129); however, this is
but one of several abnormal conditions imposed by an endoluminal
stent. Endoluminal stents are incapable of treating the radial
asymmetries or eccentricities characteristic of angiosclerotic
lesions discriminately, instead covering over unaffected portions
entirely about the arterial wall. A distinct irritant, endoluminal
stents in the vascular tree not only stimulate intimal hyperplasia
leading to restenosis, but accelerate atherosclerosis, and can
result in ischemiatizing intramedial protrusion sometimes leading
to erosions, fistulization, or fistulation, responsive to the
chronic irritation of physiologically active tissue or infection,
and interference with normal intrinsic (vasotonic and pulsatile)
motility.
[1057] An extraluminal stent is not susceptible to adhesion of
luminal contents, clogging, tumor ingrowth whether during adjuvant
therapy, or erosion, ulceration, perforation, or fistulatization of
the substrate (encircled, underlying) ductus, for example, with or
without infection, and is not capable of " . . . compressive action
of the stent into the mediastinum leading to more disease invasion
and metastatic spread in addition to more difficult resection . . .
." (Griffiths, E. A. and Powell, S. L. 2012. "Comment Re Gastric
Ulceration Following Oesophageal Stent Migration [Markar et al.
2012 cited below] Interactive Cardiovascular Thoracic Surgery
15(2):322; van Hooft, J. E., Bemelman, W. A., Oldenburg, B.,
Marinelli, A. W., Holzik, M. F., and 4 others 2011. "Colonic
Stenting Versus Emergency Surgery for Acute Left-sided Malignant
Colonic Obstruction: A Multicentre Randomised Trial," Lancet
Oncology 12(4):344-352). Griffiths and Powell wrote to dissuade the
use of stents in the digestive tract entirely.
[1058] Metastasis is more effectively averted when stays, which
avoid the lumen altogether, are used as the intravascular
component. Neither might the intravascular component of an
extraluminal stent (miniballs or stays) migrate, and proper
securing of the stent-jacket precludes its migration. Where
clearance is slight, the jacket is minimized in thickness to avert
encroachment upon or abrasion of adjacent tissue. Endoluminal
stents in the trachea or esophagus interfere with normal function
inside and within (through) the lumen wall in every way. The
literature seldom limited to a single complication, a
categorization is at best based upon relative stress.
[1059] Endoluminal stents in the gastrointestinal tract that must
be left in place over an extended rather than a brief interval
(see, for example, van Boeckel, P. G., Dua, K. S., Weusten, B. L.,
Schmits, R. J., Surapaneni, N., Timmer, R., Vleggaar, F. P., and
Siersema, P. D. 2012. "Fully Covered Self-expandable Metal Stents
(SEMS), Partially Covered SEMS and Self-expandable Plastic Stents
for the Treatment of Benign Esophageal Ruptures and Anastomotic
Leaks," BMC [BioMed Central (London)] Gastroenterology 12:19; van
Boeckel, P. G., Sijbring, A., Vleggaar, F. P., and Siersema, P. D.
2011. "Systematic Review: Temporary Stent Placement for Benign
Rupture or Anastomotic Leak of the Oesophagus," Alimentary
Pharmacology and Therapeutics 33(12):1292-1301; Langer, F. B.,
Schoppmann, S. F., Prager, G., Tomaselli, F., Pluschnig, U., Hejna,
M., Schmid, R., and Zacherl, J. 2010. "Temporary Placement of
Self-expanding Oesophageal Stents as Bridging for Neo-adjuvant
Therapy," Annals of Surgical Oncology 17(2):470-475; Small, A. J.,
Coelho-Prabhu, N., and Baron, T. H. 2010. "Endoscopic Placement of
Self-expandable Metal Stents for Malignant Colonic Obstruction:
Long-term Outcomes and Complication Factors," Gastrointestinal
Endoscopy 71(3):560-572) risk numerous complications directly
attributable to occupancy within the lumen that an extraluminal
stent avoids (see, for example, Park, S., Shin, S. J., Ahn, J. B.,
Jeung, H-C., and 3 others 2009. "Benefits of Recurrent Colonic
Stent Insertion in a Patient with Advanced Gastric Cancer with
Carcinomatosis Causing Colonic Obstruction," Yonsei Medical Journal
50(2): 296-299; Soto, S., Lopez-Roses, L., Gonzalez-Ramirez, A.,
Lancho, A., Santos, A., and Olivencia, P. 2006. "Endoscopic
Treatment of Acute Colorectal Obstruction with Self-expandable
Metallic Stents: Experience in a Community Hospital," Surgical
Endoscopy 20(7):1072-1076; Homs, M. Y., Steyerberg, E. W., Kuipers,
E. J., van der Gaast, A., Haringsma, J., van Blankenstein, M., and
Siersema, P. D. 2004. "Causes and Treatment of Recurrent Dysphagia
after Self-expanding Metal Stent Placement for Palliation of
Esophageal Carcinoma," Endoscopy 36(10):880-886; Cheng, Y. S., Li,
M. H., Chen, W. X., Chen, N. W., Zhuang, Q. X., and Shang, K. Z.
2004. "Complications of Stent Placement for Benign Stricture of
Gastrointestinal Tract," World Journal of Gastroenterology
10(2):284-286; Patel, S., Patwardhan, R. and Levey, J. 2003.
"Endoscopic Stenting: An Overview of Potential Complications,"
Practical Gastroenterology 27(6):44-54; Singh, S. and Gagneja, H.
K. 2002. "Stents in the Small Intestine," Current Gastroenterology
Reports 4(5):383-391; Christie, N. A., Buenaventura, P. O.,
Fernando, H. C., Nguyen, N. T., Weigel, T. L., Ferson, P. F., and
Luketich, J. D. 2001. "Results of Expandable Metal Stents for
Malignant Esophageal Obstruction in 100 Patients: Short-term and
Long-term Follow-up," Annals of Thoracic Surgery 71(6):1797-1802),
to include:
[1060] a. Migration (dislocation, displacement) (see, for example,
Macdonald, A. J., Drummond, R. J., and Wright, D. M. 2007.
"Migration of a Metal Esophageal Stent Presenting as Obstruction at
the Ileocecal Valve 2 Years Postinsertion," Endoscopy 39 Supplement
1:E190; Maetani, I., Isayama, H., and Mizumoto, Y. 2007.
"Palliation in Patients with Malignant Gastric Outlet Obstruction
with a Newly Designed Enteral Stent: A Multicenter Study,"
Gastrointestinal Endoscopy 66(2):355-360; Ho, H. S. and Ong, H. S.
2004. "A Rare Life-threatening Complication of Migrated Nitinol
Self-expanding Metallic Stent (Ultraflex)," Surgical Endoscopy
18(2):347; Di Fiore, F., Lecleire, S., Antonietti, M., Savoye, G.,
and Savoye-Collet C, and 4 others 2003. "Spontaneous Passage of a
Dislocated Esophageal Metal Stent: Report of Two Cases," Endoscopy
35:(3)223-225; De Palma G D, Iovino P, and Catanzano C. 2001.
"Distally Migrated Esophageal Self-expanding Metal Stents: Wait and
See or Remove? Gastrointestinal Endoscopy 53:(1)96-98).
[1061] b. Migration of a primary gastrointestinal or enteral stent
(one originally placed in rather than migrating into the digestive
tract) resulting in perforation (see, for example, Morikawa, S.,
Suzuki, A., Nakase, K., and Yasuda, K. 2012. "Palliation of
Malignant Upper Gastrointestinal Obstruction with Self-expandable
Metal Stent," Korean Journal of Radiology 13 Supplement 1:S98-103;
Havemann, M. C., Adamsen, S., and Wojdemann, M. 2009. "Malignant
Gastric Outlet Obstruction Managed by Endoscopic Stenting: A
Prospective Single-centre Study," Scandinavian Journal of
Gastroenterology 44(2):248-251; Mosler, P., Mergener, K. D.,
Brandabur, J. J., Schembre, D. B., and Kozarek, R. A. 2005.
"Palliation of Gastric Outlet Obstruction and Proximal Small Bowel
Obstruction with Self-expandable Metal Stents: A Single Center
Series," Journal of Clinical Gastroenterology 39(2):124-128;
Thumbe, V. K., Houghton, A. D., and Smith, M. S. 2000. "Duodenal
Perforation by a Wallstent," Endoscopy 32(6):495-497; von
Schonfeld, J. 2000. "Endoscopic Retrieval of a Broken and Migrated
Esophageal Metal Stent," Zeitschrift fur Gastroenterologie
38(9):795-798). Duodenal perforation by migration of a biliary
stent is addressed below.
[1062] c. Migration resulting in fistulization (Melendez, J., Chu,
D., Bakaeen, F. G., and Casal, R. F. 2011. "Tracheoesophageal
Fistula Due to Migration of a Self-expanding Esophageal Stent
Successfully Treated with a Silicone "Y" Tracheobronchial Stent,"
Journal of Thoracic and Cardiovascular Surgery 141(6):e43-e44;
Furlong, H., Nasr, A., and Walsh, T. N. 2009. "Gastropleural
Fistula: A Complication of Esophageal Self-expanding Metallic Stent
Migration," Endoscopy 41 Supplement 2:E38-E39).
[1063] d. Migration resulting in ulceration (Markar, S. R., Ross,
A., and Low, D. E. 2012. "Gastric Ulceration Following Oesophageal
Stent Migration Complicating Surgical Management of Oesophageal
Cancer," Interactive Cardiovascular and Thoracic Surgery
15(2):320-322; Rao, K. V., Beri, G. D., and Wang, W. W. 2010.
"Trimming of a Migrated Metal Stent for Malignant Colonic Stricture
Using Argon Plasma Coagulation," World Journal of Gastrointestinal
Endoscopy 2(2):75-76; Molina-Infante, J., Mateos-Rodriguez, J. M.,
Fernandez-Bermejo, M., Perez-Gallardo, B., and Hernandez-Alonso, M.
2010. "Endoscopic Trimming of an Embedded Distally Migrated
Metallic Rectal Stent with Argon Plasma Coagulation," Surgical
Laparoscopy, Endoscopy and Percutaneous Techniques
20(2):e73-e75).
[1064] e. Direct (in place, at the location where originally
implanted, nonmigratory) perforation (Dittmar, Y., Rauchfuss, F.,
Schmidt, C., and Settmacher, U. 2011. "Abdominothorakale
Osophagusresektion wegen Osophagusstentperforation bei
metastasiertem Magenkarzinomrezidiv im Stadium der kompletten
Remission--eine Kasuistik," [Palliative Abdominothoracic Resection
for Stent-induced Perforation of the Oesophagus in a Patient with
Recurrent Metastatic Gastric Cancer with Complete Remission--A Case
Report] Zentralblatt fur Chirurgie 6 April ISSN 1438-9592; Jung, G.
S., Park, S. D., and Cho, Y. D. 2008. "Stent-induced Esophageal
Perforation: Treatment by Means of Placing a Second Stent after
Removal of the Original Stent," Cardiovascular and Interventional
Radiology 31(3):663-668; Ely, C. A. and Arregui, M. E. 2003. "The
Use of Enteral Stents in Colonic and Gastric Outlet Obstruction,"
Surgical Endoscopy 17(1):89-94; Christie et al. 2001 op cit.).
[1065] f. Direct fistulization (Guarner-Argente, C.,
Chandrasekhara, V., Levine, M. S., Marcotte, P. J., Weinstein, G.
S., and Ginsberg, G. G. 2011. "Esophageal Stent-induced
Fistulization to an Anterior Cervical Plate," Gastrointestinal
Endoscopy 74(1):219-221; Han, Y., Liu, K., Li, X., Wang, X., Zhou,
Y., and 6 others 2009. "Repair of Massive Stent-induced
Tracheoesophageal Fistula," Journal of Thoracic and Cardiovascular
Surgery 137(4): 813-817; Schowengerdt, C. G. 1999.
"Tracheoesophageal Fistula Caused by a Self-expanding Esophageal
Stent," Annals of Thorac Surgery 67(3):830-831).
[1066] g. Direct ulceration (Wei, W., Ramaswamy, A., de la Torre,
R., and Miedema, B. W. 2012. "Partially Covered Esophageal Stents
Cause Bowel Injury when Used to Treat Complications of Bariatric
Surgery," Surgical Endoscopy 27 June [e-publication ahead of
print]; Wai, C. T., Khor, C., Lim, S. E., and Ho, K. Y. 2005.
"Post-metallic Stent Placement Bleeding Caused by Stent-induced
Ulcers," World Journal of Gastroenterology 11(36):5739-5741).
[1067] h. Tumor ingrowth that can make removal of the stent
impossible without much dissection (Griffiths, E. A. and Powell, S.
L. 2012 op cit.] Interactive Cardiovascular Thoracic Surgery
15(2):322; Lopera, J. E. and de Gregorio, M. A. 2010. "Fluoroscopic
Management of Complications after Colorectal Stent Placement," Gut
and Liver 4(Supplement 1):59-518; Kang, S-G., Jung, G. S., Cho, S.
G., Kim, J. G., Oh, J. H., Song, H. Y., and Kim, E. S. 2002. "The
Efficacy of Metallic Stent Placement in the Treatment of Colorectal
Obstruction," Korean Journal of Radiology 3(2):79-86; Scheider, D.
M., Siemens, M., Cirocco, M., Haber, G. B., Kandel, G., Kortan, P.,
and Marcon, N. E. 1997. "Photodynamic Therapy for the Treatment of
Tumor Ingrowth in Expandable Esophageal Stents," Endoscopy
29(4):271-274).
[1068] i. The accumulation of detritus and clogging or impaction
(see, for example, Loffeld, R. J. L. F. and Dekkers, P. E. P. 2012.
"Palliative Stenting of the Digestive Tract: A Case Series of a
Single Centre." Journal of Gastrointestinal Oncology August
[available at http://www.thejgo.org/article/view/497]; de Gregorio,
M. A., Laborda, A., Tejero, E., Miguelena, J. M., Carnevale, F. C.,
and 4 others 2011. "Ten-year Retrospective Study of Treatment of
Malignant Colonic Obstructions with Self-expandable Stents,"
Journal of Vascular and Interventional Radiology 22(6):870-878; de
Gregorio, M. A., Mainar, A., Rodriguez, J., Alfonso, E. R., and 4
others 2004. "Colon Stenting: A Review," Seminars in Interventional
Radiology 21(3):205-216).
[1069] Endoluminal biliary stents require to be changed every 3 to
6 months and bring complications to include those associated with
primary enteral stents (see, for example, Kida, M., Miyazawa, S.,
Iwai, T., Ikeda, H., Takezawa, M., and 4 others 2011. "Endoscopic
Management of Malignant Biliary Obstruction by Means of Covered
Metallic Stents: Primary Stent Placement Vs. Re-intervention,"
Endoscopy 43(12):1039-1044; Brinkley, M., Wible, B. C., Hong, K.,
and Georgiades, C. 2009. "Colonic Perforation by a Percutaneously
Displaced Biliary Stent: Report of a Case and a Review of Current
Practice," Journal of Vascular and Interventional Radiology
20(5):680-683; Arhan, M., Odemi , B., Parlak, E., Ertu rul, I., and
Ba ar, O. 2009. "Migration of Biliary Plastic Stents: Experience of
a Tertiary Center," Surgical Endoscopy 23(4):769-775; Lee, T. H,
Park, D. H., Park, J. Y., Lee, S. H., Chung, I. K., Kim, H. S.,
Park, S. H., and Kim, S. J. 2008. "Aortoduodenal Fistula and Aortic
Aneurysm Secondary to Biliary Stent-induced Retroperitoneal
Perforation," World Journal of Gastroenterology 14(19):3095-3097;
Namdar, T., Raffel, A. M., Topp, S. A., Namdar, L. and 4 others
2007. "Complications and Treatment of Migrated Biliary
Endoprostheses: A Review of the Literature," World Journal of
Gastroenterology 13(40):5397-5399; Suk, K. T., Kim, J. W., Kim, H.
S., Baik, S. K., Oh, S. J., and 5 others 2007. "Human Application
of a Metallic Stent Covered with a Paclitaxel-incorporated Membrane
for Malignant Biliary Obstruction: Multicenter Pilot Study,"
Gastrointestinal Endoscopy 66(4):798-803; Paikos, D., Gatopoulou,
A., Moschos, J., Soufleris, K., Tarpagos, A., and Katsos, I. 2006.
"Migrated Biliary Stent Predisposing to Fatal ERCP-related
Perforation of the Duodenum," Journal of Gastrointestinal and Liver
Diseases 15(4):387-388; Matsushita, M., Takakuwa, H., Nishio, A.,
Kido, M., and Shimeno, N. 2003. "Open-biopsy-forceps Technique for
Endoscopic Removal of Distally Migrated and Impacted Biliary
Metallic Stents," Gastrointestinal Endoscopy 58(6):924-927;
Galandi, D., Schwarzer, G., Bassler, D., and Allgaier, H. P. 2002.
"Ursodeoxycholic Acid and/or Antibiotics for Prevention of Biliary
Stent Occlusion," Cochrane Database of Systematic Reviews
(3):CD003043; Yau, K. K., Tang, C. N., Chau, C. H., Siu, W. T.,
Fung, K. H., and Li, M. K. 2000. "Nonoperative Management of
Biliary Stent-induced Duodenal Perforation," Endoscopy 32(8):S47;
Yarze, J. C., Poulos, A. M., Fritz, H. P., and Herlihy, K. J. 1997.
"Treatment of Metallic Biliary Stent-induced Duodenal Ulceration
Using Endoscopic Laser Therapy," Digestive Diseases and Sciences
42(1):6-9).
[1070] Obstruction or perforation of the gut by a biliary stent
that migrated is heavily reported in the literature (see, for
example, Bharathi, R. S., Rao, P. P., and Ghosh, K. 2008.
"Intra-peritoneal Duodenal Perforation Caused by Delayed Migration
of Endobiliary Stent: A Case Report," International Journal of
Surgery 6(6):478-480; Melita, G., Curr , G., Iapichino, G.,
Princiotta, S., and Cucinotta, E. 2005. "Duodenal Perforation
Secondary to Biliary Stent Dislocation: A Case Report and Review of
the Literature," Chirurgia Italiana 57(3):385-388). Attempts to
devise an endoluminal biliary stent less susceptible to clogging
(Raju, G. S., Sud, R., Elfert, A. A., Enaba, M., Kalloo, A., and
Pasricha, P. J. 2006. "Biliary Drainage by Using Stents Without a
Central Lumen: A Pilot Study," Gastrointestinal Endoscopy
63(2):317-320) appear to pose greater risk of incisions and
perforations.
[1071] Side by side placement poses inordinate difficulty and risks
(Lee, T. H., Park, D. H., Lee, S. S., Choi, H. J., Lee, J. K. and 5
others 2012. "Technical Feasibility and Revision Efficacy of the
Sequential Deployment of Endoscopic Bilateral Side-by-Side Metal
Stents for Malignant Hilar Biliary Strictures: A Multicenter
Prospective Study," Digestive Diseases and Sciences, e-pub ahead of
print August 2011). Stents with side holes has been tried and did
not eliminate clogging (Coene, P. P., Groen, A. K., Cheng, J., Out,
M. M., Tytgat, G. N., and Huibregtse, K. 1990. "Clogging of Biliary
Endoprostheses: A New Perspective," Gut 31(8):913-917).
[1072] Notwithstanding, endoluminal stenting of the
gastrointestinal tract to include the esophagus and small intestine
is often effectively palliative for treating malignant stenosis
(see, for example, Mergener, K. and Kozarek, R. A. 2002. "Stenting
of the Gastrointestinal Tract," Digestive Diseases 20(2):173-181;
Guo, J. H., Teng, G. J., Zhu, G. Y., He, S. C., Fang, W., Deng, G.,
and Li, G. Z. 2008. "Self-expandable Esophageal Stent Loaded with
125 I Seeds: Initial Experience in Patients with Advanced
Esophageal Cancer," Radiology 247(2):574-581). However, no
limitation to malignancies should be assumed even for metal stents
(see, for example, Small, A. J., Young-Fadok, T. M., and Baron, T.
H. 2008. "Expandable Metal Stent Placement for Benign Colorectal
Obstruction: Outcomes for 23 Cases," Surgical Endoscopy
22(2):454-462; Evrard, S., Le Moine, O., Lazaraki, G., Dormann, A.,
El Nakadi, I., and Deviere, J. 2004. "Self-expanding Plastic Stents
for Benign Esophageal Lesions," Gastrointestinal Endoscopy
60(6):894-900; Dormann, A. J., Deppe, H., and Wigginghaus, B. 2001.
"Self-expanding Metallic Stents for Continuous Dilatation of Benign
Stenoses in Gastrointestinal Tract--First Results of Long-term
Follow-up in Interim Stent Application in Pyloric and Colonic
Obstructions," (in English) Zeitschrift fur Gastroenterologie
39(11):957-960).
[1073] Whether due to primary deformity or pathological
deterioration, protracted impairment in physiological function from
immobilization over time further destroys normal structure and
function in the lumen wall. Even though the smooth muscle has
deteriorated or atrophied, a stent that complies in expansion and
contraction without irritation assists to preserve what normal
vascular physiology remains. The thrombogenic turbulent flow at its
margins aggravated by the thrombophilic metal surface of every
practical endoluminal stent from the moment of placement poses the
risk of thrombosis as long as the stent remains, which almost
always, is to the end of life (see for example, Manjappa, N.,
Agarwal, A., and Cavusoglu, E. 2006. "Very Late Bare-metal Stent
Thrombosis. A Case Report and Review of the Literature," Journal of
Invasive Cardiology 18(7): E203-E206).
[1074] An endoluminal stent thus requires antithrombotic
(antithrombogenic) medication in addition to the statin that would
be necessary to control the dyslipidemic (hypercholesterolemic)
etiological condition in any event. An extraluminal stent allows
dispensing with the lifelong administration of antithrombotic
medication and the bleeding problems to which this can predispose.
Furthermore, magnetic drug targeting makes it possible to limit
exposure to the statin to localized segments. For a younger
patient, this allows the myopathic effect associated with long term
use of a statin to be avoided. In addition to disrupting
endothelial function, endoluminal stents conflict with autonomic
(vasotonic angiotonic) adjustment in lumen diameter to adjust the
blood pressure (arterial tension) by direct mechanical
interference.
[1075] Compliance in caliber is indissociable from changes in the
pulse. The presence of an endoluminal stent can interfere with the
re-treatment that will most often be due to the etiology, which no
stent, even one drug-eluting or radiation-emitting, can ordinarily
more than palliate, and the stent may itself have aggravated if not
precipitated the condition. Retrieval, however, usually bodes
significant trauma. Thousands of references on file at the U.S.
National Library of Medicine document the fracture, fragmentation,
migration, clogging, and susceptibility to act as a scaffold for
the deposition of constituents out of the passing fluid of an
endoluminal stent of any kind in any kind of ductus. In producing
these consequences, endoluminal stents introduce mechanical as well
as physiological complications that often precipitate the need for
a second procedure, sometimes involving open surgery, to effect
their removal.
[1076] 8b. The Extraluminal Stent
[1077] An extraluminal stent consists of an intravascular
component, which is multiple, and a singular extravascular
component that mantles about or ensheaths the intravascular
component. The intravascular component consists of stays or
miniballs. The extravascular component, or stent-jacket, is used to
maintain the stenosed or collapsed ductus at its normal quiescent
caliber without interfering with its normal expansion and
contraction. If stenosed as plaque laden, an angioplasty is
normally performed so that the lumen will be adequate. Nonvascular
ductus are analogously rid of obstructive matter or tissue through
ablation. The magnetic function is directed inward, or adaxially,
using the axially directed poles of the permanent magnets about the
jacket, with the jacket itself limiting expansion to the extent
normal.
[1078] The radially outward attractive field generated by a
stent-jacket are seldom used, and then with the aid of
ferromagnetic implants placed in the tissue to be pulled at,
whether to pull either the other structure or the encircled or
substrate ductus itself aside when one or the other follows a
course correctible thus or encroaches on adjacent tissue, for
example. Only tissue to be acted upon as positioned along the
magnetic path or circuit, not an encircled ductus used as a magnet
mounting platform to pull or be pulled, need have ferromagnetic
implants. That by incorporating nonmagnetized bars, pellets, disks,
or if quasi-intrinsic, an embedded particulate, stent-jackets and
magnet-wraps which use the substrate ductus only as a mounting
platform can serve as the attracted rather than the attracting
component, is obvious. Attraction is then in the direction set by
the magnetized magnet-wrap, patch-magnet, or stent-jacket used to
attract the nonmagnetically mantled ductus.
[1079] A stent-jacket placed about a nearby vessel or duct can also
be used, for example, to concentrate drug carrier particles in an
organ or a certain area within that organ. Radially outward
function in larger vessels and ducts is accomplished with the aid
of a discrete magnet stent-jacket, or if more distant, then a
magnet-wrap, which is essentially a stent-jacket that has been
modified to incorporate larger discrete magnets. When the mounting
platform for effecting distant retraction or drug targeting is not
tubular, patch-magnets are used. In order to encircle (girdle,
mantle, jacket, or grasp about) a tubular structure or ductus of
which the deep side would best be left attached, the side-slit of
the base-tube is expanded into a side-slot wide enough to clear
(straddle) the attachment.
[1080] A side-slot constitutes an enlarged side-slit or
longitudinal expansion gap that is usually but not always situated
at the deep side. Such a stent-jacket with a longitudinal strip
removed is a partial stent-jacket. Unlike an endoluminal stent, the
extraluminal stent need not impose sufficient radially outward
force at the margins to prevent dislodgement (migration). Small
branches at the slit can be accommodated either with a cutout at
the slit or by expanding the slit into a slot, that is, extending
the cutout sideways out to the ends. Cutouts to clear larger
branches and expansion inserts to clear a swollen ductus apply
equally to full and partial stent-jackets. By contrast, existing
endoluminal stents are continuous in structure and unable to retain
structural integrity when a void must be introduced to span a
branch, for example.
[1081] Complementary thereto, in placing an intravascular component
consisting of miniballs, a void is accommodated by temporarily
replacing a rotary magazine clip feeding multiple radially directed
barrel-tubes in the airgun chamber with one that blanks out the
barrel-tubes directed toward the void of the ostium (the opening
into the branch). While the angle separating the exit-ports about
the muzzle-head is not variable, the exit-ports that discharge at a
given time is instantly changeable. For a given arrangement of
exit-ports, blanking out the hole in the rotary clip for loading
the miniballs for each to exit through its corresponding
barrel-tube allows each barrel-tube to be fed or left unfed per
discharge on discharge by discharge discretionary basis.
[1082] This allows changing the discharge pattern as to arcuate
distribution at any moment such as to target or to avoid an
eccentric lesion or ostium, for example. Significantly, it does
this without the need to withdraw one radial discharge
barrel-assembly and replace it with another. A barrel-assembly is
generally made to a certain gauge, any additional features provided
to allow use in the vascular tree. Barrel-assembly versatility
means sufficiency that eliminates the need for withdrawal and
reentry, which expedites completion of a procedure, significantly
reduces the risks of hematoma and infection at the entry wound, and
materially reduces the number of different Barrel-assemblies which
must be produced or purchased. Stays are similarly placed to avoid
the blanked out area.
[1083] In treating eccentric lesions, note is taken of the
positions of the lesions throughout the course of the vascular
system to be treated and the choice of a fully radially discharging
muzzle assembly with occasional blanked out rotary magazine clips
or partially radially discharging muzzle assembly with exit ports
at a different, usually smaller angle, made on this basis.
Minimizing the duration of the procedure and any further trauma to
the usually inguinal or brachial point of entry, the choice is
based upon avoiding the need to withdraw one barrel-assembly and
replace it with another. To keep the size and mass of the
stent-jacket to a minimum as least to encroach upon or rub against
adjacent tissue, the magnets should be as diminutive as possible
consistent with the magnetic force required.
[1084] To this end, small sintered neodymium iron boron
(Nd.sub.2Fe.sub.14B) permanent bar magnets of megagauss oersted
(MGO) 50 or higher grade material are used. The magnets are
magnetized parallel to their thickness, or normal to their plane;
that is, the lines of force run radial in relation to the long axis
of the ductus to be treated. Readily corroded, neodymium iron boron
magnets are often available already nickel plated in a length that
spans the implanted miniballs lengthwise, or running parallel to
the axis of the tubing. However, commercially available neodymium
magnets are not made in the tiny sizes required, and neither
neodymium iron boron nor nickel is biocompatible (see International
Standards Organization standard series 10993, Biological Evaluation
of Medical Devices.
[1085] Bioinertness is attained by overlayment or encapsulation of
the bar magnets in gold, tantalum, titanium, or any of the large
number of nondegrading bioinert plastic polymer resins. The use of
other noble metals, such as platinum, rhodium, and alloys of
platinum and rhodium are needlessly expensive. The magnets are
drilled through toward each of their ends or perimeters prior to
being coated or encapsulated for bioinertness, then fastened to the
base-tube with rivets or eyelets. Since placing the stent-jacket
about the ductus with the insertion tool to be described may
necessitate the application of lateral force to the sides the
magnets with end of a probe, and the magnets must not come loose
during application or at any time thereafter, wider flange rivets
or eyelets are used.
[1086] Tantalum coating the magnets enhances radiopacity making
radiological visualization and if necessary, retrieval, easier. The
cylindrical base-tube is relatively stiff lengthwise, but unless
too thick, long, or made of stiffer material, flexible
circumferentially about the side-slit as to comply with the pulse.
Within the constraints imposed by the need to generate sufficient
field strength, this isolates longer magnets from flexing forces,
allowing the use of magnets that are thin for clearance and to
avoid encroachment upon neighboring tissue. Otherwise, the
brittleness of sintered neodymium iron boron, even when nickel
plated and encapsulated for bioinertness in gold plate further
sputter coated or microfused would allow thin magnets to quickly
fail.
[1087] The lack of sufficient strength is more pronounced for gross
movement at points of flexion where the material and dimensions do
not add sufficient ultimate strength or resistance to breaking
stress for the bending load. Resistance to magnet fracture and
longitudinal flexibility without resistance to bending by a long
base-tube that spans a point of flexion is obtained by segmenting
the stent-jacket, as addressed below in the section entitled
Sectional, or Chain-stents, Segmented and Articulated. However,
whether preaneurysmally, where disease has weakened the arterial
wall, longitudinal segmentation of the magnets on an especially
flexible continuous and longer base-tube can offer compliance with
the pulse while jacketing about the vessel to prevent its
rupture.
[1088] Compliance with the pulse or smooth muscle action is
obtained through the use of suitable stent-jacket base-tube
materials, which may be coextruded or as addressed below in the
section entitled Laminated Stent-jackets, laminated (layered),
varying the relative thicknesses of the layers, and if necessary,
using shorter bar magnets or segmented stent-jackets. If necessary,
the magnets can be strengthened by using thicker and/or stronger
encapsulation materials of gold, tantalum, titanium, and a bioinert
plastic polymer resin, alone or in combination posing a spectrum of
choices. Endoluminal stents cannot be used to reduce the risk of
rupture and are noncompliant with intrinsic movement.
[1089] 8b(1). The Intraductal Component of the Extraluminal Stent
and the Means for its Insertion
[1090] 8b(1)(a). Types of Ductus-Intramural Implants Used for
Stenting
[1091] The intraductal component of a magnetic extraluminal stent
consists of an array of miniballs or stays containing sufficient
magnetically susceptible material, typically ferromagnetic, to
maintain the lumen in a patent condition. Stenting miniballs and
stays can include drugs, other therapeutic substances, bonding
agents, or a radiation-emitting seed.
[1092] 8b(1)(b). Use of Ductus-Intramural Implants for Stenting
[1093] Miniballs are implanted with a barrel-assembly, stays with a
stay insertion tool. Ductus-intramural implants and implantation
for stenting are no different than when stenting is uninvolved, the
differences pertaining to higher ferromagnetic content and the
additional need to place a stent-jacket. Stays used to attract a
drug carrier particulate must also contain more ferromagnetic
content, which must be magnetized. For stenting, miniballs are
attracted, not attracting. Stays, however, which asymmetical, pose
no problem of magnetic orientation, can atttract a ferrous
stent-jacket, but unless also used to attract a drug carrier
particulate, are contituted as would miniballs.
[1094] Each type apparatus is variously configurable for different
purposes, as addressed below in sections on each type apparatus.
When the lumen wall is weakened, wide stays coated with
cyanoacylate cement when ejected from the stay insertion tool are
used. Either type implant can include medication, any of numerous
other therapeutic substances, and/or incorporate a radionuclide
with or without radiation shielding. Stays highly magnetized
radially in relation to the long axis of the ductus can also be
used to draw magnetically susceptible drug carrier nanoparticles
from the passing contents, the ductus usually an artery and the
contents blood. Miniballs are not used thus due to the need to
orient these with an external electromagnet, risking
extraction.
[1095] If the stays emit radiation, then the surrounding tissue and
nanoparticles can be irradiated upon arriving in the target lesion.
The density, or number of implants per unit area of the wall, is
proportional to the reduction in wall strength and coordinated with
the extraluminal component to avoid the concentration of tractive
force on any one stay. A ductus too weak to be stented in this way
is probably too weak to be stented in any way, and should be
replaced with a graft. When the outer layer of a ductus lacks
sufficient strength to sustain the tractive force needed to
maintain patency, a ferromagnetic wrap-surround is engaged by means
of ferromagnetic stainless steel or superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder impregnated
plastic prongs (anchors, clasps) into the tunica media to provide a
prosthetic adventitia.
[1096] Implantation at body temperature of medicated miniballs with
a thermal or cryogenic ablation or ablation and angioplasty-capable
barrel-assembly makes implantation followup measures immediately
available without the need for withdrawal and reentry. Whether
following a thermal or cryogenic ablation or angioplasty, thermal
or cryogenic use of the same barrel-assembly can be used to
initiate the release of medication or time-release medication from
implanted miniballs, to accelerate the dissolution of either by
melting or contraction fracture of a miniball coating, or by the
use of heat to accelerate the dissolution of the implant through
the hydrolysis of ester bonds, for example.
[1097] The same processes are applicable to stays and stent-jacket
expansion inserts as addressed below in the section entitled
Expansion Inserts Absorbable, Meltable, and Comminutable for
Time-discrete Decremental Contraction of Stent-Jackets. These
various implants can be not only irradiative and/or coated with
medication, but incorporate agents to control their dissolution,
which agents can also liberate medication. Stays and miniballs to
serve as irradiating seeds need not contain ferromagnetic material
as is necessary for use with a stent-jacket. However, the inclusion
of ferrous material such as superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder in seeds makes it
possible to recover the seeds after any interval with the aid of a
magnet stronger than those placed about stent-jackets.
[1098] From the standpoint of timing, miniballs and stays that
incorporate ferrous material can be placed for use as seeds, and
once depleted of radiation, whereupon the neoplasm should have
subsided, can be used as the intraductal components of a
stent-jacket. Conventional seeds imaged ultrasonographically or by
means of computed tomography, seed-stays not conventionally marked
or coated for radiopacity can be encapsulated with a layer that
includes a gamma emitting isotope for gamma camera viewing. Within
the size constraints, stays can be encapsulated with medicine.
Miniballs of like purpose can be of like composition as stays.
[1099] The use of the methods and apparatus described herein to
implant spherules that consist solely of medication and/or serve as
a substrate for the emission of radiation from a highly localized
site within the wall of a tubular anatomical structure, for
example, are addressed above in the section entitled Drug-releasing
and Irradiating Ductus-intramural Implants and below in the
sections entitled Radiation-emitting (Brachytherapeutic,
Endocurietherapeutic, Sealed source Radiotherapeutic, Internal
Radiation Therapy) Miniballs and Medication Miniballs.
[1100] Any barrel-tube can be used to infix a medicated, multiple
concentric medicated, and/or irradiating implant along the wall of
a ductus thus causing the medication to be eluted or radiation to
be emitted in a highly localized, discretionary manner, rather than
circulated throughout the bloodstream. In the coronary arteries,
most other vessels, and other type narrow gauge ductus, the
transluminal advancement of a multibarrel radial discharge
barrel-assembly by means of an automatic positional control system,
as will be described, allows a higher density and uniform spacing
between adjacent miniballs than might be achieved with direct
manual control.
[1101] A uniform distribution of millimetric or smaller miniballs
draws the diseased or weakened wall of the ductus more as a sheet,
minimizing the concentration of tractive force on certain
miniballs, and thus reduces for any of these to be pulled entirely
through the adventitia, referred to as pull-through, or avulse the
abaxial tunic or tunics, referred to as delamination. Failure by
pull-through or delamination of a threshold proportion of miniballs
produces stent failure (breakdown, loss of retractiion). High
density ductus-intramural implantation also allows placement within
the same area of a larger number, hence greater diversity of
miniballs to allow a larger amount or variety of medication and/or
other therapeutic substances.
[1102] Miniballs can be formulated to spontaneously release
medication known to be effective or to become released and
physiologically activated only in response to external control on
an as needed basis through direct or induction heating or the
ingestion, injection, or infusion of another substance as
appropriate, these various methods of attack delineated in sections
of appropriate title. Since it better resists pull-through, the use
of a larger number of miniballs to cover the same area is less
susceptible to deterioration of the stent and the patency the stent
will continue to provide. When apposite, a thermal angioplasty
performed after discharge can be used to flow a solid protein
solder outer shell applied to miniballs with an undercut-textured
surface.
[1103] Protein solder or any other bonding agent used in the body
will eventually be dissipated and lose all bonding value; however,
through the infiltration and replacement of the solder by tissue
that fills the fissures or channels at the surface, the miniballs
become integrated into the tissue. When the condition permits, this
process is allowed to be completed before the stent-jacket is
applied. By allowing successive discharges to be made quickly and
accurately, the use of a positional control system allows the use
of a barrel-assembly having the largest number of barrel-tubes that
the diameters of the miniballs and ductus to be implanted will
allow. With the possible exception of off-pump warm treatment in
the coronary or carotid arteries, the resulting reduction in
procedural time is considerable and should allow operation under
conditions of brief if substantial occlusion.
[1104] Since the miniball implants are encapsulated for
bioinertness and small (typically 0.4-1.0 millimeter in a ureter or
artery, for example), a perforation is quickly and spontaneously
sealed; unless septic contents are released, the loss of a miniball
into the surrounding body cavity, for example, will have little
significance. Also militating against pull-through in an artery is
the fitting of the stent-jacket for the diastoles or as little more
distended than any post ablation, angioplasty or atherectomy
residual narrowing of the lumen will allow. In the gastrointestinal
tract, the release of cell contents along the trajectory of the
miniball contributes tack that congeals and is gradually replaced
so that the miniball is left integrated into healthy tissue.
[1105] One or more barrels, or barrel-tubes, housed within an gas
embolism-averting gas pressure equalizing enclosure, or
barrel-catheter, discharge forward and radially through a distal
muzzle-probe or muzzle-head. The leading, or distal, component
through which the spherules are discharged, or muzzle-head, is
usually placed in flush or slightly less than flush relation to the
wall of an arterial lumen (channel, passageway), the passing pulse
expands the vessel about the muzzle-head. The muzzle-head also has
grooves to allow blood to pass, albeit with some impedance and
shear stress compared to the unobstructed condition.
[1106] However, the procedure is completed too quickly to allow
shear much less stretching injury, especially when discharge is
semiautomatic. Multiple discharge capability and the application of
a positional control system also serve to minimize procedural time.
When the muzzle-head is of the kind that delivers a plurality of
spherule implants each in a different direction with each
discharge, eccentricity of the muzzle-head within the lumen on
passage of the pulse has little effect upon the spherule impact
force. In most instances, the density of implants will also
compensate for minor differences in the aiming point that results
from excursion of the lumen wall about the muzzle-head.
[1107] 8b(2). The Extraductal Component of the Extraluminal Stent
and the Means for its Insertion
[1108] 8b(2)(a). Types of Stent-Jacket
[1109] So that the operator or a technician can adapt standardized
stent- and perforation shield-jackets to the conditions
encountered, these are generally supplied without expansion inserts
or straight-line and double-wedge linings inserted. Expansion
inserts to be bonded along one or both edges of the side-slit or
side-slot and lap over a length of the outer surface for bonding
without encroaching upon the lining along the inner surface are
likewise supplied separately for preprocedural selection as
appropriate. Unless used other than to prevent a perforation from
striking neighboring tissue, such as to provide warming by neat
induction at a later date, shield-jackets are placed only
midprocedurally, so that an expansion insert is not pertinent to
this type jacket. The incorporation of silicon-iron crystal into
implants to be magnetically susceptible affords reduction in the
mass and space taken up by both the attracting jacket or its bar
magnets or electromagnets and the attracted implant and is
therefore taken advantage of to the extent possible.
[1110] Nonmagnetic shield-jackets and magnetic stent-jackets must
incorporate a side slit or slotted elastic sheath, a component to
exert magnetic force over the surface of the sheath, and a moisture
barrier-coated viscoelastic polyurethane foam lining, the latter
perforated in alignment but not encapsulated with the others and
left out of consideration as to whether a stent-jacket is
categorized as laminated. Provided the ductus will not be adversely
affected by denial of exposure to the chemical milieu, any
stent-jacket can have a radiation shield added by lamination. When
the period for shielding is limited, even a shielded jacket can be
made to absorbed, either spontaneously or by dissolution on demand,
as addressed below. The layers less moisture barrier-coated
viscoelastic polyurethane foam lining are usually encapsulated
within a chemically isolating and cushioning coating of a
plastisol-like or rubbery polymer or copolymer.
[1111] For a single layer to provide both the sheath and magnetism,
it must be intrinsically or quasi-intrinsically magnetized. To the
extent that a magnet-wrap, or magnet-jacket, addressed below in the
section entitled Magnet-wraps, is used to direct tractive force
radially inward toward the long axis of the lumen (adaxially,
axipetally, centripetally), it is a kind of stent-jacket, addressed
above in the section entitled Concept of the Extraluminal Stent and
below in the section entitled Stent-jackets and Stent-jacket
Supporting Elements, or impasse-jacket, as addressed below in the
sections entitled Concept of the Impasse-jacket and Miniball and
Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets.
[1112] Abaxial or centrifugal traction, that is, toward a
periductal sheath-mounted magnet, from the long axis of the lumen
and jacket, as opposed to adaxial or centripetal traction toward
the magnet and axis from the surrounding area is relegated to
magnet-wraps and seldom other than an inherent byproduct of using a
stent- or impasse-jacket. Stent- and impasse-jackets differ from
magnet-wraps in having a backing that is more resilient, slit or
slotted to allow the expansion and contraction of the encircled or
substrate ductus, and usually, in magnetization entirely about the
circumference. The intentional use of a magnet-wrap,
impasse-jacket, or stent-jacket for the tractive force at both
adaxial and abaxial poles is practicable but exceptional, the use
of a stent- or impasse-jacket for its adaxial attraction even more
so.
[1113] A stent-jacket must maintain luminal patency without contact
between, significant stress to, or deformation of the internal
(endothelial) surface of the lumen. If to remain in use
temporarily, as during healing, the stent-jacket is not retrieved
invasively but absorbed. Absorbable stent-jackets are addressed
below in the section entitled Absorbable Base-tube and
Stent-jacket, Miniball, Stay, and Clasp-magnet Matrix Materials. If
the period for the need of a stent is known not to be permanent but
broadly indeterminable, then the stent-jacket is chemically
formulated to dissolve noninvasively on demand, as addressed below
in the section entitled Noninvasive Dissolution on Demand of
Absorbable Stent-jackets Base-tubes and Radiation Shields.
[1114] When an intrinsically or quasi-intrinsicaly magnetized
stent-jacket or a radiation shield is bonded to a polymeric
base-tube to produce an extrinsically magnetized stent-jacket, the
whole is a laminated stent-jacket, addressed below. A shielded
stent-jacket can also be made absorbable, but the `breathing`
perforations of the underlying stent layer will be closed over.
This reduction in exposed surface lengthens the spontaneous
absorption time, further prompting means for directing dissolution
from outside the body. The term `stent-jacket` denotes a device
that incorporates all of the properties essential in the
extravascular component of an extraluminal stent. When added for
magnetization such a layer may not be suitable for use alone as an
intrinsically or quasi-intrinsically magnetized stent-jacket as
lacking resilience.
[1115] An intrinsically or quasi-intrinsically magnetized layer in
an extrinsically magnetized stent-jacket is generally specialized
for supplementary or complementary use and depends upon the
base-tube layer for the nonmagnetic properties. Reciprocally,
adding a layer to a self-sufficient stent-jacket will result in
stiffness and/or a strength of magnetization as would risk
pull-through. Even though it does not add to the magnetic strength
and can be made pliant, the addition of a a radiation shield must
take this into account. By contrast, a stand-alone single-layer
intrinsically or quasi-intrinsically magnetized stent-jacket
provides all of the properties required. Devised for different
treatment sites, the need to laminate an intrinsically or
quasi-intrinsically magnetized stent-jacket for increased magnetic
strength, resilience, or both, as by laminating two of the same or
similar stent-jackets would be exceptional.
[1116] The addition of a radiation shielding layer is seldom
required, and always produces a laminated base-tube mounting
discrete magnets or a laminated stent-jacket. Stent-jackets
suitable for radiation shielding are intrinsically,
quasi-intrinsically, or lamination-magnetized, but not
extrinsically magnetized. Others are extrinsically magnetized, one
layer, the base-tube, an elastic sheath described as discretely
magnetized when it mounts bar magnets about its outer surface and
laminated, if it mounts an intrinsically or quasi-intrinsically
magnetized layer. Discretely, intrinsically, and
quasi-intrinsically magnetized stent-jackets are unlaminated.
Lamination can also be used to increase the elasticity and/or the
magnetic force of an intrinsically or a quasi-intrinsically
magnetized stent-jacket.
[1117] Lamination may include layers both of which provide
magnetization and elasticity where the combination serves to adjust
these values; otherwise intrinsically and quasi-intrinsically
magnetized stent-jackets are not laminated. The addition or
radiation shielding yields a laminated stent-jacket wherein to
avoid excessive thickness, the other layer is almost always
intrinsically or quasi-intrinsically magnetized. These various
alternatives make it possible to achieve any practical combination
of properties in the thickness needed for circumductal clearance.
The rate of spontaneous demagnetization of current permanent
magnets allows permanent implantation. Magnetic stent-jackets are
also characterized as slit, or full-round, or slotted, or partially
round.
[1118] 8b(2)(a)(i). Extrinsically Magnetized Stent-Jackets
[1119] Extrinsically magnetized stent- and impasse-jackets derive
tractive force through the fastening about the outer surface of the
jacket base-tube of permanent or electromagnets. Where a consistent
minimal field force is to be increased for certain attractants
infused in a ferrofluid, small electromagnets are added to the
permanent magnets to comprise a hybrid type jacket. Control of
electromagnets is by an implanted microprocessor as addressed below
in sections XXI and XXII. Mounting tiny bar magnets about a length
of elastic tubing with the tractive force oriented perpendicularly
(radially) to the tube, or base-tube, provides a circumductal
(periductal, circumvascular, perivascular) sheath (sleeve,
surround), or stent-jacket.
[1120] Slit along one side, such a sleeve is able to expand and
contract, hence, comply with changes in the diameter or gauge of a
tubular structure whether tonic, pulsatile, or peristaltic. To
avoid gouging of the surrounding tissue, the magnets are flattened,
and to prevent abrasion, the edges are rounded and encapsulated.
The surrounding tissue in contact with the ductus adapted to comply
with its intrinsic movement, where such contact exists, the magnets
are surface textured to encourage tissue adhesion, infiltration,
and stabilization, thus warding off abrasive irritation.
Nonabsorbable stent-jackets are encapsulated in a chemically
isolating biocompatible polymeric coating and lined with moisture
barrier-coated viscoelastic polyurethane foam.
[1121] An intrinsically magnetized stent-jacket of stainless steel
has the distinct advantage of immunity to the development of
microfractures with a consequent loss in resilience or a loss in
magnetization either of which would result in a loss of function.
The vessel or duct is kept patent by a mild outward pull upon the
lumen wall toward the internal surface of the surrounding
circumvascular stent-jacket. The ability of an extraluminal stent
to move with the intrinsic movement in the ductus stands in marked
contrast to the fixation in diameter and outward radial force
against the lumen wall imposed by endolumnal stents.
[1122] While endoscopic coagulation or embolization remain
preferable for treating ectasic (distended, dilated) blood vessels
where collateral circulation allows these to be eliminated, an
extravascular stent with or without magnetization, as appropriate,
is applicable to reducing the luminal diameter of other ectasic
ductus, whereas an endoluminal stent is not. A general awareness as
to the potential of percutaneously introduced circumvascular
sheaths to treat embedded vessels is evidenced by the awarding by
the Radiological Society of North America of research grants in
2001 and 2002 for a project entitled Percutaneous Placement of
Extraluminal Stent-Graft: A New Concept for Treatment of Occlusive
Disease in the Superficial Femoral Artery. To date, the project has
not yielded published results.
[1123] Such anastomosis and containment by extraductal sheaths,
stents, or stent-grafts does not include bar magnets on the outer
surface or ferromagnetic ductus intramural implants and has little
if any relation to the stent-jackets to be described herein. A
base-tube with spaced apart or discrete bar magnets applied to its
outer surface, or an extrinsically magnetized stent-jacket, has the
advantages of 1. Virtually unlimited magnetic force for
applications such as attracting drug carrier nanoparticles from a
ferrofluid with slight if any effect upon jacket elasticity, 2.
Avoiding the need to a. Impregnate the polymeric base-tube itself
with a magnetized particulate, thus reducing the relative
proportion of continuous tubing material essential for longer life
in a jacket of given thickness; or b. Adding another layer
consisting of intrinsically magnetized metal tubing or a magnetized
particulate-impregnated polymeric layer, which laminated, adds to
the thickness of the base-tube, and 4. Assembly from off-the-shelf
or standard components.
[1124] For high visiblity, when encapsulated for chemical isolation
within gold, for example, the tiny bar magnets are contrast marked
with a coating of tantalum, for example. When the magnets and
substrate base-tube are encapsulated together, the marking material
such as tantalum is used to outline the magnets by vapor or sputter
deposition onto the outer surface of the outer coating of the
polyethylene terephthalate, for example, used to encapsulate the
stent-jacket for chemical isolation. In no instance is the moisture
barrier-coated viscoelastic polyurethane foam lining encapsulated.
A polymeric base-tube laminated with intrinsically magnetized metal
tubing or a magnetized particulate-impregnated polymeric layer is
also extrinsically magnetized; however, lamination is its most
salient characteristic and used to classify it as extrinsically
magnetized laminated, or extrinsic laminated.
[1125] A nonlaminated, extrinsically magnetized stent-jacket has
the disadvantages of at least slight protrusion radially outwards
of the magnets, creating the potential for the jacket to rub
against and abrade the surrounding tissue, nonuniform distribution
of the tractive force over the base-tube, a conformation unamenable
to the addition of a radiation shield by lamination, and if the
magnets are stronger, can deflect the muzzle-head interfering with
discharge accuracy forcing the use of an intrinsically or
quasi-intrinsically magnetized stent-jacket or the use of stays
rather than miniballs. The thinness of intrinsically and
quasi-intrinsically magnetized stent-jackets is advantageous where
completely uniform slight to moderate field strength is
required.
[1126] Such pertains, for example, to stenting of the coronary
arteries, which course through a thin layer of fatty connective
tissue between the visceral pericardium or epicardium and the
myocardium, and peripheral arteries that course through a sheath
amid the muscles of the limb. Because it eliminates these
deterrents, a quasi-intrinsically magnetized stent-jacket,
addressed below, which additionally eschews the pliancy-thickness
to achieve the ferromagnetic mass required factor posed by of an
intrinsically magnetized stent-jacket such as one made of thin
stainless steel sheet, is that most widely applicable. The
extrinsic type is that shown in the drawing figures for reasons of
pictorial clarity. Whether discrete magnets are advantageous or
disadvantageous depends upon the need for concentrating the
tractive force. When magnets and implants are properly aligned and
it is desired that the traction be concentrated on these implants,
and/or a drug carrier particulate is to be drawn, the use of
discrete magnets is beneficial.
[1127] However, discrete magnets generally distribute magnetic
traction less evenly about the ductus, so that if the magnets and
susceptible miniballs or stays are not radially aligned, tangential
vectors will urge the miniballs or stays sideways as well as
radially outwards. If pronounced, this will interfere with
compliance of the stent to the expansion and contraction of the
ductus. The fewer and more clearly marked are magnets and
miniballs, the less difficult will it be to align these, but the
greater will be the concentration of traction. When a multibarrel
radial discharge barrel-assembly under the control of a positional
control system is used to lay down a tight formation of miniballs
for the purpose of evenly distributing the traction on diseased or
malacotic tissue, the misalignment of those more axial
ductus-intramural implants will be less, but the greater will be
the traction on the miniballs aligned to the axes or poles of the
magnets.
[1128] Nonuniform tractive force increases the risk for
pull-through, or pulling the miniballs entirely out the side of the
ductus wall resulting in stent failure. Spaced apart magnets will
also yield the uneven uptake of a magnetic carrier
particle-delivered drug into the ductus wall. The term `base-tube`
denotes a platform for magnets; nonplatform stent-jackets such as
intrinsic, addressed next, are properly designated not base-tubes
but stent-jackets. Generally, extrinsically laminated stent-jackets
include a discretely magnetized layer only when the circumductal or
perivascular clearance poses no concern for abrasion of the
surrounding tissue.
[1129] Affording adjustability of the tractive force exerted on
magnetically susceptible implants and constituents within
ferrofluids, jackets rendered magnetic by affixing electromagnets
about the outside of the base-tube are of special value in stent-
and impasse-jackets. As with permanent magnet jackets,
progressively increasing the field strength moving along the jacket
as a gradient array allows a more uniform uptake along the luminal
wall of a susceptible component introduced into the circulation as
superparamagnetic iron oxide nanoparticles or microparticles, for
example, and whereas the tractive force exerted is fixed with
permanent or bar magnets, intrinsically magnetized base-tubes, and
these combined in hybrid jackets, direct current electromagnets
allow adjustment in the tractive force exerted by each of the
successive magnets in accordance with the susceptibility of the
attractant.
[1130] An important factor in avoiding patient discomfort,
electromagnets for implantation, especially when wound with silver
wire, can be made to generate considerable field strength while
much lighter in weight than the equivalent neodymium magnets, for
example. Unlike permanent and intrinsic/permanent stent- and
impasse-jackets, electromagnets are not limited to a minimum
residual field force beyond a slight bias following degaussing, or
demagnetization, easily obtained by automatically passing direct
current through the magnets in reverse. That is, compelled to
project a minimum field, permanent and hybrid intrinsic/permanent
and intrinsic/electromagnet jackets are limited in adjustability at
the low end to some positive value, and since almost any intended
field strength would be greater, this represents a considerable
limitation.
[1131] The ability to effectively eliminate the magnetic field is
important in allowing infusants to pass jackets magnetized thus and
instead continue through the circulation, urinary, or digestive
tract to the jacket at the treatment site intended. The
adjustability in field strength of electromagnets allows
susceptible infusants and treatment sites to be matched in
attracter/attractant pairs, so that each susceptible infusant in a
`cocktail` of infusants or numerous infusants consecutively
administered effectively seek out the jacket at the treatment site
for which that infusant is intended. Selective targeting thus is of
particular value in the treatment of comorbidity where numerous
drugs must be targeted to different organs or tissues and the
atradtion of any of these to the wrong jacket could result in
complications.
[1132] When necessary to minimize outward protrusion about the
jacket, electromagnets are wound with silver wire and the
attractant or attractants provided with only so much subembolic
micrometric Si-Fe crystal as sufficiently enhances magnetic
susceptibility for the electromagnets to draw these into the lumen
wall, for example. Adjustability in field strength allows fine
tuning or `trimming` for the susceptibility of the attractant and
conditions such velocity of passage through the bloodstream and
intermingling with food without the need to impose upon the patient
to first purge the digestive tract with polyethelene glycol and
electrolytes, for example.
[1133] Control over the shape of traction to meet the instant need
is structural and established by the angle at which the jacket is
applied to the substrate ductus, which the force to exerted
responsive to a given infusant is encoded in the prescription
program. The efficiency of stent and impasse-jackets, allowing
their minimization in size and mass, is economically increased by
including silicon-iron crystal in the attractants. To treat
eccentric lesions, both permanent and electromagnets can be aligned
along one side of the jacket; otherwise, the magnets are arranged
however best responds to the conformation of the lesion to be
treated. When remodeling or the antecedent therpy alters the
conformation of the lesion, a distribution of magnets about the
jacket can be changed in energization to complement the concomitant
geometry.
[1134] Electromagnets allow such flexibility where intrinsically
magnetic jackets do not. Conventional solenoid electromagnets are
conformed for attachment to the base-tube with the coil winding
arranged lengthwise, allowing it to be rounded flush to the
base-tube for minimal radially outward protrusion; compactness in
implants vitiates the risk of abrading contact with neighboring
tissue, producing chronic irritation and raising concerns for
fistulation and other complications. The coils are always enclosed
within a shell to cover over sharp edges, corners, and any
protrusions.
[1135] Depending upon the space constraints, electromagnets can be
conventional solenoid, spiral, bifilar, or Ayrton-Perry wound
bifilar (see, for example, Caverhill-Godkewitsc, S. 2015. Modeling
of Integrated Microfluidics-CMOS Lab-on-chip Technology, Thesis,
Department of Electrical and Computer Engineering, University of
Alberta, section 3.8.1. "CMOS Spiral Electromagnet," page 52;
Santra, A., Chakraborty, N., and Ganguly, R. 2009. "Analytical
Evaluation of Magnetic Field by Planar Micro-electromagnet Spirals
for MEMS [microelectromechanical systems] Applications," Journal of
Micromechanics and Microengineering 19(8):10 pages, online;
Beyzavi, A. and Nguyen, N.-T. 2008. "Modeling and Optimization of
Planar Microcoils," Journal of Micromechanics and Microengineering
18(9):8 pages, online; Choi, J. W., in Minteer, S. D. (ed.) 2006.
Microfluidic Techniques: Reviews and Protocols, Totowa, N.J.:
Humana Press, section 3, page 70; Lund-Olesen 2005. Integrated
Microfluidic Mixer and Magnetic Bead Separator, Thesis, Institute
of Micro and Nanotechnology, Technical University of Denmark; Choi,
J. W., Liakopoulos, T. M., and Ahn, C. H. 2001. "An On-chip
Magnetic Bead Separator Using Spiral Electromagnets with
Semi-encapsulated Permalloy," Biosensors and Bioelectronics
16(6):409-416; Kirschvink, J. L. 1992. "Uniform Magnetic Fields and
Double-wrapped Coil Systems: Improved Techniques for the Design of
Bioelectromagnetic Experiments," Bioelectromagnetics
13(5):401-411). To present a minimized cross section as not to
encroach upon neighboring tissue, these are rounded for flush
application around the outer surface of the base-tube.
[1136] Where the function of the stent-jacket is substantially
consistent with an occasional need for increased tractive force,
electromagnets can be added to an intrinsically magnetized jacket
to constitute a type of hybrid stent-jacket as addressed below in
section 8b(2)(a)(iii), entitled Hybrid Extrinsically and
Intrinsically Magnetized Stent-jackets. Electromagnets added to an
extrinsically magnetized jacket with permanent magnets allow
discriminatory adjustments in field strength to differentially draw
attractants of different susceptibility. When the individual
components, both intrinsic jackets and electromagnets, are in
regular production, such a hybrid can be made smaller in size and
mass and at less expense. An intrinsically magnetic jacket can be
magnetized to treat an eccentric lesion. The addition of small
electromagnets to an intrinsically magnetic jacket, however, allows
adjusting the jacket to treat the lesion following remodeling or a
subsidence in eccentricity.
[1137] As addressed below in sections XX, entitled Exemplary
Channel of Control in a Fully Implanted Ambulatory Adaptive
Hierarchical Control System for Automatic Response to a Comorbid
Condition and XXI, entitled Fully Implanted Ambulatory Adaptive
Hierarchical Control Systems for Automatic Response to a Comorbid
Condition, exclusively and hybrid electromagnet stent-jackets can
be controlled by an implant microprocessor. Such control is
governed by a prescription-program that automatically adjust each
electromagnet of the stent-jacket in accordance wity the medication
or agent administered through a small port at the body surface.
[1138] When the microprocessor directs the outlet motors of
implanted small flat drug reservoirs to release the medication so
that the identity and dose of each drug is known to it, the
prescription program automatically adjusts the field strength of
the magnets accordingly. When the drugs are injected through the
body surface port, the identity and dose of each drug is typed into
the microcontroller with a computer tablet. Electromagnets also
represent an additional mode of susceptible matter recovery,
especially important were a potentially embolizing miniball to pass
into the circulation, other methods of recovery addressed at
numerous points herein.
[1139] 8b(2)(a)(ii). Intrinsically Magnetized Stent-Jackets
[1140] In an intrinsically magnetized stent-jacket, the tubing
material is itself magnetized and does not require the addition of
magnetic material whether in the form of permanent magnets mounted
about the outer surface or, as in a quasi-intrinsically magnetized
stent-jacket, by embedding, laminating, or adding a coating of
another susceptible material. Intrinsically magnetized
stent-jackets uniformly project tractive magnetic force over the
length of the jacket. This is suitable for radially symmetrical but
not eccentric lesions, adjustability obtained by adding small
neodymium permanent or elecgtromagnets, for example.
[1141] Numerous magnetic polymers and metals available and under
development can be used (see, for example, Gi ynski, K., Lee, T.,
and Grzybowski, B. A. 2017. "Dynamic Self-assembly of
Magnetic/Polymer Composites in Rotating Frames of Reference,"
Advanced Materials (Deerfield Beach, Fla.) 29(33); Kalia, S.,
Kango, S., Kumar, A., Haldorai, Y., Kumari, B., and Kumar, R. 2014.
"Magnetic Polymer Nanocomposites for Environmental and Biomedical
Applications," Colloid and Polymer Science 292(9):2025-2052;
Thevenot, J., Oliveira, H., Sandre, O., and Lecommandoux, S. 2013.
"Magnetic Responsive Polymer Composite Materials," Chemical Society
Reviews 42(17):7099-7116; Philippova, O., Barabanova, A.,
Molchanov, V., and Khokhlov, A. 2011. "Magnetic Polymer Beads:
Recent Trends and Developments in Synthetic Design and
Applications," European Polymer Journal 47(4):542-559; Nishide, H.
and Suga, T. 2011. "Magnetic Polymers," Encyclopeda of Polymer
Science and Technology online at
http://onlinelibrary.wiley.com/doi/10.1002/0471440264; Masi, J. V.
2007. "New Magnetic Polymers," in Institute of Electrical and
Electronics Engineers 2007 Electrical Insulation Conference and
Electrical Manufacturing Expo[sition] at
http://ieeexplore.ieee.org/document/4562641/; Zaidi, N. A., Giblin,
S. R., Terry, I., and Monkman, A. P. 2004. "Room Temperature
Magnetic Order in an Organic Magnet Derived from Polyaniline,"
Polymer 45(16):5683-5689).
[1142] To augment its magnetic force, iron powder dispersed in a
polyvinyl acetate matrix can be coated onto an otherwise
intrinsically magnetized thin stainless steel or polymeric core.
Rolled magnetic or nonmagnetic stainless steel or polymer sheet can
be laminated with iron powder in a matrix of polyvinyl acetate, for
example, encapsulated for chemical isolation and this in turn
supplemented with permanent or electromagnets.
[1143] Materials currently under development may make it possible
to consolidate an intrinsically magnetized base-tube and foam
lining in a single material (see, for example, Fafenrot, S.,
Grimmelsmann, N., Wortmann, M., and Ehrmann, A. 2017.
"Three-dimensional (3D) Printing of Polymer-metal Hybrid Materials
by Fused Deposition Modeling," Materials (Basel, Switzerland)
10(10). Eventually, a single material may also be capable of drug
release, although nonreplenishably, that is, to a finite limit
(see, for example, Alhijjaj, M., Belton, P., and Qi, S. 2016. "An
Investigation into the Use of Polymer Blends to Improve the
Printability of and Regulate Drug Release from Pharmaceutical Solid
Dispersions Prepared via Fused Deposition Modeling (FDM) 3D
Printing," European Journal of Pharmaceutics and Biopharmaceutics
108:111-125).
[1144] Intrinsically and quasi-intrinsically magnetized
stent-jackets can eliminate a clearance problem that would present
were an extrinsically magnetized stent-jacket used. Unlike
austenitic or nickel-containing 300 series stainless steels,
martensitic and most precipitation carbon hardenable nickel free
stainless steels, to include types 410, 416, 420, 440B, 440C, and
17-4, when magnetized in the hardened condition, are capable of
permanent magnetization. A less strongly magnetizable stainless
spring steel such as 18-8 at spring temper may require the addition
of a nonabsorbable polymer coating with embedded chemically
isolated neodymium granules.
[1145] An intrinsically magnetized stent-jacket is cut from a
length of thin martensitic stainless steel flat sheet stock cold
worked to impart a mildly shape restorative or springy character,
uniformly pre-magnetized, and thereafter formed into the short tube
so that the tractive force is oriented radially or normal to the
long axis of the base-tube and the ductus it is to encircle.
Intrinically magnetized stent-jackets can be made of very thin
sheet or tubing to achieve the thnnest profile of any such jacket.
This increases the applicability of these and quasi-intrinsically
magnetized stent-jackets next to be described, which are almost as
thin, to peripheral arteries, for example, where circumvascular
clearance makes the placement of discretely magnetized jackets
inadvisable.
[1146] Unlike discrete magnet stent-jackets, which produce a
nonuniform field with a focus at each of the magnets, intrinsically
and quasi-intrinsically magnetized stent-jackets produce a field
that is uniform and well matched to a dense formation of miniballs
used precisely to avoid a concentration of tractive force on one or
a few implants as might then pull through or result in
delamination. Shaping into a tube is by forming over a mandrel
while heating to a sub-Curie temperature of about 200 to 300
degrees centigrade, then oil quenching. The temperature will depend
upon the metallurgy and thickness, but should be less than 310 to
400 degrees centigrade for Nd.sub.2Fe.sub.14B (sintered) or 800
degrees centigrade for Sm(Co, Fe, Cu, Zr) (sintered).
[1147] In some instances exceeding the Curie temperature will not
prevent the spontaneous recovery of doman alignment and
magnetization once the material cools. The slit or slot where the
long edges oppose serves as the expansion joint. The sheet must be
sufficiently resilient to compensate for the repulsion of like
poles in diametric opposition entirely about the jacket. The same
material can be punched and magnetized in halves to form the
extraction grid of an impasse-jacket. The primary considerations
are compliance with the motility of the substrate (treated) ductus
and use of the least magnetic force that will maintain the lumen in
an undistended or stretched patent condition.
[1148] Since jacket resilience and the repulsion should balance out
leaving the pulse or peristalsis as the driving force, the primary
objective of compliance should not significantly limit the
resilience or restorative force of the jacket needed to compensate
for the circular repulsion whether due to its thickness or
metallurgy. It has the advantages of unobtrusive thinness and a
substantially even distribution of magnetic force entirely about
the ductus as complements a close and even distribution of
miniballs placed by a multibarrel radial discharge barrel-assembly
under the control of a positional control system. This is generally
less important for application along the gastrointestinal tract
where the forces, thickness and strength of the tissue, and
clearance afforded are considerable but critical for the treatment
of a diseased artery, for example.
[1149] Such uniformity of the tractive force may be essential when
treating a diseased ductus that would otherwise be further
aggravated and/or a malacotic ductus that would be ruptured.
However, due to the thinness essential for flexibility, the mass of
ferromagnetic material is limited and the special magnetization
required must be accomplished upon manufacture. Nevertheless, with
diseased and/or malacotic tissue, mild stenting traction may be
suitable. An intrinsically magnetized stent-jacket can represent a
component layer in a laminated stent-jacket, referred to as
intrinsically magnetized laminated, or intrinsic laminated, wherein
the other layer is usually polymeric or quasi-intrinsically
magnetized, and discretely magnetized only when the circumductal
clearance poses no concern for abrasion of the surrounding
tissue.
[1150] The development of magnetic polymers that can be made to
specified mechanical properties at room temperature and implanted
with or without a chemically isolating encapsulating outer layer
will make possible not only novel microspheres and nanoparticles
but intrinsically magnetized stent-jackets of a polymeric rather
than metallic basis (see, for example, Fu, H. H., Yao, K. L., and
Liu, Z. L. "Magnetic Properties of Very-high-Spin Organic
Pi-conjugated Polymers Based on Green's Function Theory," Journal
of Chemical Physics 2008 129(13):134706; Naveed, A., Zaidi, S. R.,
Giblin, I., Terry, and Monkman, A. P. 2004. "Room Temperature
Magnetic Order in an Organic Magnet Derived from Polyaniline,"
Polymer 45(16): 5683-5689; Rajca, A., Wongsriratanakul, J., Rajca,
S., and Cerny, R. L. 2004. "Organic Spin Clusters: Annelated
Macrocyclic Polyarylmethyl Polyradicals and a Polymer with Very
High Spin S=6-18," Chemistry 10(13):3144-3157; Rajca, A.,
Wongsriratanakul, J., and Rajca, S. 2001. "Magnetic Ordering in an
Organic Polymer", Science 294(5546):1503-1505; Thorpe, M. F. 1976.
"Magnetic Polymers," in Proceedings, 34th Conference, American
Institute of Physics, Issue 5, Volume 22, page 13, Ann Arbor,
Mich.: University of Michigan Press). This would allow increased
latitude in the relation between strength of magnetization and
stent-jacket thickness and elasticity while eliminating the
surrounding clearance limitation with extrinsically magnetized
stent-jackets.
[1151] 8b(2)(a)(iii). Hybrid Extrinsically and Intrinsically
Magnetized Stent-Jackets
[1152] Hybrid extrinsically and intrinsically magnetized
stent-jackets are briefly addressed above in section 8b(2)(a)(i),
entitled Extrinsically Magnetized Stent-jackets. Intrinsically
magnetic jackets represent the form factor of least mass and volume
but generally limited in field strength, intrinsically magnetic
jackets may necessitate the incorporation of silicon-iron crystal
in the attractant. This is of cardinal importance in applications
involving small children and wherever the jacket, even though
encapsulated to smooth over sharp edges and corners would otherwise
encroach on neighboring tissue.
[1153] 8b(2)(a)(iv). Quasi-Intrinsically Magnetized
Stent-Jackets
[1154] A quasi-intrinsically magnetized stent-jacket incorporates
magnetic material by embedment, lamination, or jacketing rather
than by mounting permanent magnets about its outer surface. As it
substantially distributes the tractive force uniformly
notwithstanding the minimal number and size of perforations to
expose the underlying tissue to its normal milieu, is readily
laminated, does not tie flexibility to the thickness required to
achieve the necessary magnetic strength, can be made with smooth
faces, and affords numerous options in detailed formulation, this
is the most common form of stent-jacket. A quasi-intrinsically
magnetized stent-jacket consists of a length of polymeric flat
sheet stock with a ferromagnetic particulate embedded in the
polymer or copolymer which is then sectioned with each section
formed into a mildly resilient side-slit or slotted cylinder with a
side-slit or side-slot, the heat used to form the tubes well below
the Curie temperature.
[1155] Intrinsically and quasi-intrinsically magnetized
stent-jackets are superior to the discrete magnet type when uniform
magnetization and traction are desired. Magnetization while the
material remains flat allows the particulate to be uniformly
magnetized and oriented, so that the tractive force will be exerted
radially or normal to the long axis of the base-tube entirely about
the circumference and thus entirely about the ductus it will
encircle. The particulate is added while the polymer matrix remains
amorphous (semimolten, fluid). When the matrix material resists
shaping into mildly resilient tubes by applying heat, the tubes are
formed ab initio by extrusion, then temporarily held opened flat to
uniformly magnetize the ferrous particulate added to the mix while
amorphous. For a given thickness, the discontinuity among embedded
particles less reduces jacket flexibility than does the continuous
metal in an intrinsically magnetized stent-jacket.
[1156] Radiation shielding can be integrated into the jacket in the
form of particulate tungsten, for example, which nonmagnetic, will
not affect the magnetic character of the jacket but necessarily
continuous, will add to jacket thickness and resilience as it
relates to ductus compliance as the primary requirement. To reduce
the number of distinctive stent-jackets and for simplicity,
radiation shielding is applied by laminating a preexisting
quasi-intrinsic stent-jacket with a separate layer of shielding
material, usually tungsten. The sandwiching with or addition of an
intrinsically magnetized stent-jacket to a polymeric jacket or to a
quasi-intrinsically magnetized stent-jacket yields a compound
intrinsically and polymeric or quasi-intrinsically magnetized
laminated stent-jacket. Extrinsic magnetization is used when
greater magnetic force must be exerted in a targeted manner.
[1157] For uniform distribution of the tractive force, thinness,
and amenability to lamination such as to add a radiation shield
layer, most stent-jackets are single layered, or intrinsically or
quasi-intrinsically magnetized. These retain the limitation on the
thickness of the intrinsically magnetized component that will allow
the degree of flexibility required. Lamination of a
quasi-intrinsically magnetized stent-jacket with a plain polymeric
layer yields a quasi-intrinsically magnetized laminated, or
quasi-intrinsic laminated stent-jacket. The other layer is discrete
extrinsic magnetized only when the circumductal clearance poses no
concern for abrasion of the surrounding tissue. If the
quasi-intrinsically magnetized stent-jacket is absorbable, then
seeds other than the magnetized particulate embedded within the
base-tube may be used to accelerate its dissolution when heated,
for example. One such approach is to prompt a chemical reaction
that releases water within the jacket, expediting its dissolution
through hydrolysis.
[1158] Other polymers may call for the release of an enzyme, for
example. An absorbable quasi-intrinsically magnetized stent-jacket
normally uses magnesium as the metal matrix. The magnetized
particulate is a compound of iron or a lanthanoid. Extraluminal,
the iron and any nontoxic magnesium alloy ingredients for imparting
resilience to the magnesium are not absorbed through the gut and
dissolve at a rate too slow to reach a serum concentration that is
toxic. An abosorbable stent-jacket can be used with absorbable
stays or miniballs, likewise consisting of a glycolic acid derived
polymer or copolymer, such as polylactic coglycolic polymer with
embedded ferrous matter encapsulated as necessary for chemical
isolation. Larger total amounts of iron or a more toxic
particulate, such as one of neodymium iron boron, must be overlain
with a nonabsorbable polymeric coating suitable for
implantation.
[1159] 8b(2)(a)(v). Laminated Stent-Jackets
[1160] Lamination allows adding numerous capabilities,
modifications, or combinations of these to a base layer or an
existing stent-jacket. These include increased resilience by adding
another simple, compound, particulate and/or mesh-containing
polymeric and/or metallic layer. Adding a layer containing
sufficiently continuous electrically conductive ferromagnetic
material allows remote, noninvasive, heating of the jacket by
placing the patient in a radiofrequency alternating magnetic or
electromagnetic field. The material is added by mixing granular
elemental iron or small ferrous plates into the amorphous polymer
matrix before extrusion.
[1161] The temperature attainable depends upon the strength and
frequency of the magnet as well as the overall mass, continuity,
and distribution of the iron. The same composition pertains to
other components such as miniballs, as addressed below in the
section entitled Noninvasive Dissolution on Demand of Absorbable
Stent-jackets, Base-tubes, Radiation Shields, and Miniballs.
Encapsulation in an absorbable jacket is essential only if the
potential serum concentration of iron might obtain. The frequency
and amplitude of the heat generating eddy current inducing
alternating magnetic or electromagnetic field must be increased to
compensate for resistance due to particulate discontinuity and the
number of `breathing` perforations in the stent-jacket to allow gas
exchange.
[1162] Remote heatability can be used to release or accelerate the
release of a drug, of water and/or an enzyme thereby enabling the
dissolution on demand of the layer itself or of an absorbable
jacket as a whole; reduce pain or discomfort as heat or
hyperthermic therapy; accelerate drug uptake and healing, reduce
surgical adhesive setting and curing times; flow a protein solder
of low denaturing temperature; or these in any combination. This
property is valuable for applying thermoplasty where followup
examination reveals reobstruction such as due to intimal or medial
hyperplasia. More specifically, incorporating ferrous plates or
adding a layer containing overlapped elevated temperature-tolerant
chemical isolation-encapsulated tungsten particulate in a
nonresilient matrix layer need not significantly reduce the
flexibility, hence, compliance with the motility of the substrate
ductus, while providing remote heatability and radiation shielding
in a layer that can be nonabsorbable for long term use, absorbable,
or absorbable on demand.
[1163] An added layer can be used to increase the strength of
magnetization of and/or add a radiation shield to a base-layer
intrinsically or quasi-intinsically magnetized stent-jacket. Adding
a second intrinsically or quasi-intinsically magnetized layer to an
existing intrinsically or quasi-intrinsically magnetized
stent-jacket of like polarity can be used to increase, or if of
opposing polarity, then to reduce, the magnetic strength. This
ability to supplement or modify an existing stent-jacket allows
greater versatility at less cost than producing myriad specialized
single-layer stent-jackets, and can be used to avoid the protrusion
of discrete magnets mounted about the outer surface of the
base-tube. When necessary; lamination allows adding resilience;
however, the compliance of the resulting combination to the
autonomic action in the substrate ductus must not be significantly
degraded.
[1164] Extrinsic magnetization or the use of permanent magnets
pertains when the circumductal clearance poses no concern for
abrasion of the surrounding tissue, the addition of an outer lamina
is uninvolved, and contrast marking the magnets is unproblematic.
When the jacket as a whole is radiopaque, contrast marking,
generally with tantalum, is applied to the outer coating applied
for chemical isolation. The magnets tiny, rounded in peripheral
contour, and cushioned by the encapsulating coating, encroachment
is seldom a problem. If absorbable, an additional embedded
particulate can be incorporated into the stent-jacket to accelerate
its dissolution such as when heated. If metal, the base-tube
consists of magnesium alloyed for resilience where the alloy
substances are nontoxic. A radiation shielded stent-jacket is
laminated. The material of the shield layer is intrinsic, such as
tungsten, or is quasi-intrinsic as embedded in a matrix.
[1165] 8b(2)(a)(vi). Spine and Ribs-Type Stent-Jackets
[1166] Spine and ribs-type stent-jackets are a variant of the
segmented stent-jacket of the kind shown in FIG. 13 where the width
of the segments is smaller or the rate of interruption increased to
allow the ribs to better comply with peristalsis and accommodate
vessels or nerves that would pass through the intervening spaces.
The viscoelastic polyurethane lining and division into radiating
fingers or ribs at intervals serve to reduce encroachment upon the
small nerves, microvasclature, and vasa recta (see, for example,
Kolton, W. A. and Pappas, T. N. 1997. "Anatomy and Physiology of
the Small Intestine," in Greenfield, L. J., Mulholland, M. W.,
Oldham, K. T., Zelenock, G. B., and Lillemoe, K. D. (eds.),
Surgery: Scientific Principles and Practice, Section D, Small
Intestine, Chapter 26, pages 805-817) associated with
gastrointestinal tract as might precipitate dysphagia or
odynophagia. The esophagus, for example, is profusely innervated by
branches and plexus of the vagus nerve.
[1167] The distance of excursion posed by peristalsis significant
along the gastrointestinal tract, for example, spine and
ribs-configured stent-jacket or rib jacket is intended to provide
highly resolved compliance to the intrinsic motion of the ductus in
the longitudinal direction. Compliance thus is essential to avoid
dysphagia, for example. Miniature versions of this kind of
stent-jacket can be applied to vessels where preservation of vessel
support as acts to sustain endothelial function is important.
Conforming to any of the variants described above in the section
entitled Types of Stent-jacket, most often, such a stent-jacket
will be intended for application to larger ductus such as those
comprising the digestive tract. The spine is configured to allow
the degree of flexion necessary. For such application, the
stent-jacket will usually consist of an elastic (flexible, flexile,
pliant) continuous longitudinal connecting or communicating bridge
or band with elastic side fingers at intervals to reach about the
substrate ductus which is used to encircle the ductus at its
quiescent outer diameter.
[1168] In essence, it is a stent-jacket with slits or slots along
the length added to that longitudinal for increased compliance
notwithstanding being monolithic, that is, cut into a single piece
of material. Because each longitudinally successive pair of fingers
contracts and expands independently of the others, more highly
resolved compliance in gauge along the stent-jacket is obtained
than might be obtained from a length of continuous elastic tubing.
This sequential flexibility makes a spine and ribs-configured
stent-jacket suitable for placement along the digestive tract,
wherein the form of peristalsis consists of successive traveling
contractive waves that propel the lumen contents forward, often
producing a bulge ahead of the contraction. Spine and ribs type
stent-jackets can be radiation shielded. Extension of the jacket
beyond the source of radiation at either end allows some negligible
breathing or exchange of gases to the ductus surface, as addressed
below in the section entitled Radiation Shield-jackets and
Radiation Shielded Stent-jackets Absorbable and Nonabsorbable.
[1169] The resolution of compliance is set by the width of and the
distance that separates the consecutive ribs or fingers, which like
the contractive waves accommodated, are equidistant. Lined with
moisture barrier-coated viscoelastic polyurethane foam, the ribs or
fingers are widely variable in width, present no sharp edges, and
have free ends slightly recurved to minimize injury to neighboring
tissue. The dual agonistic and antagonistic action of factors
released by periadventitial adipose tissue and the disruption in
endothelial function when fat is excessive are addressed below in
the section entitled Accommodation of the Adventitial Vasculature,
Innervation, and Perivascular Fat. To assist in dissecting away
excess surrounding fat and thus eliminate prominences from within
the stent-jacket while leaving a uniform thickness of proximate fat
that may contribute to endothelial function, a miniature spine and
ribs-type stent-jacket for placement about an artery can be
provided with razor sharp edges. The ribs are placed to avoid any
significant vasa or nervora, the foam lining also serving to
accommodate the gradual reduction in diameter along the gut.
[1170] Reference to such a form as a `jacket` despite continuity
limited to the connecting spine is prompted by its function as a
unit and by analogy with elastic tube-type stent-jackets. Such a
stent-jacket is usually cut from a continuous length of thin and
pliant magnetizable stainless steel tubing by numerically
controlled hydrojet, then lined with moisture barrier-coated
viscoelastic polyurethane foam as necessary. Where compliance
demands a thinness that is inconsistent with the strength of
magnetization required, the metal form is coated with a polymer
having particles of neodymium iron boron or other lanthanoid, for
example, embedded. Polymeric materials of rubbery consistency are
too soft and lack sufficient resilience for such use; however, if
coated with an outer layer containing magnetized particles, any
biocompatible harder plastic material of suitable flexibility and
thickness can be used. In that case, the stent can be produced as a
continuous strip analogous to a segmented stent-jacket.
[1171] Distinction among stent-jackets by the form of magnetization
is addressed above in the section entitled Types of Stent-jacket.
While most often intrinsically or quasi-intrinsically magnetized as
are other stent-jackets, spine and ribs-configured stent-jackets
can also be extrinsically magnetized or magnetized by lamination,
as dictated by the clearance surrounding the treated segment. A
stainless steel that can be magnetized to the field strength
required within the thickness that provides the proper resilience
is suitable. A moisture barrier-coated viscoelastic polyurethane
foam lining is provided to protect the fine nerves and vessels that
enter and depart from the outer surface of the ductus. If used to
stent, the restorative force of the stent material should be no
more than is necessary to retain the external surface of the
substrate ductus flush against the foam lining. Also to prevent
pull-through, broad stays, which pose greater resistance to
pull-through than do miniballs, are used.
[1172] Then insertion of both the ductus-intramural and
extravascular components is through a local access portal usually
an incision of 5 centimeters, the need for endoluminal access
eliminated and therewith, any deflection of the muzzle-head as the
magnetized arms are passed as could detract from discharge
accuracy. If used to attract drug carrier nanoparticles from a
passing ferrofluid, then no more resistance to flexion than would
induce dysphagia is applied. Insertion is thorugh a laparoscopic
portal, the ribs sufficiently retracted and held open by spanning
these over the outer surface of the spine with pressure sensitive
tape with a nonadherent tab at one end. Once positioned with the
internal surface of the spine lining against the ductus, the tape
is peeled away by grasping the tab with a tweezers or biopsy
forceps to free the ribs to close about the ductus. All of the
absorbable components addressed herein, whether ductus-intramural
implants, jackets, or shield-jackets, can be formulated to break
down spontaneously by hydrolysis and/or enzymatic action or
incorporate substances susceptible to solvents that allow early or
discretionary dissolution on demand.
[1173] 8b(2)(a)(vii). Absorbable Stent-Jackets
[1174] Absorbable stent-jackets and other type implants described
herein must be exposed to hydrolytic and enzymatic breakdown and
are not encapsulated in a chemically isolating and cushioning
nonabsorbable polymeric capsule, casing, or coating. Chemical
isolation is therefore limited to encapsulating any particulates
embedded within a quasi-intrinsic stent-jacket as matrix or applied
to a base-tube as a coating thereto that are toxic, adversely
reactive, or abrasive, such as magnetic lanthanoid or sintered
osmium powder particulate used as radiation shielding, which
spontaneously oxidizes to osmium tetroxide, which is toxic.
[1175] Absorbable extraluminal magnetic stent-jackets and
base-tubes are addressed below in the sections entitled Absorbable
Extraluminal Magnetic Stent-jackets and Materials and Absorbable
Base-tube and Stent-jacket, Miniball, Stay, and Clasp-magnet Matrix
Materials. Absorbable materials are always subject to premature
dissolution under conditions of fever, infection, or an
accumulation of aqueous fluid as in edema or ascites. An absorbable
jacket that both retracts subadventitial implants and provides
radiation shielding is laminated of bonded or fused component
lamina of which the inner provides stenting and the outer
shielding.
[1176] A fully absorbable extraluminal stent can also use
absorbable implants in or to abut againstbthe lumen wall. These can
be placed with any kind of barrel-assembly as shown in FIGS. 31,
32, 38, 39, 48, 49, 65, 66, 71, and 78 or any kind of stay
insertion device as shown in FIGS. 87 thru 91 Alternatively, when
an intravascular component is to dissolve while in abutting
relation with the lesion, a permanent magnet stent-jacket is first
endoscopically positioned about the substrate ductus and the
intraluminal component infused as microspherules or in a ferrofluid
as fused superparamagnetic iron oxide nanoparticles.
[1177] When the intravascular component is to be drawn into the
lumen wall, the stent-jacket is provided with small electromagnets.
To minimize outward protrusion about the jacket, these
electromagnets are wound with silver wire and the implants
incorporate only so much subembolic micrometric Si-Fe crystals as
sufficiently enhances attractability for the electromagnets to draw
these into the lumen wall. Any of these temporary stent
intravascular components can and usually do incorporate
anti-inflammatory and other medication.
[1178] 8b(2)(a)(viii). Radiation Shield-Jackets and Radiation
Shielded Stent-Jackets Absorbable and Nonabsorbable
[1179] A radiation shield or absorbable radiation shield can be
applied to any stent-jacket, whether extrinsically, intrinsically,
or quasi-intrinsically magnetized and whether the underlying
stent-jacket consists of a length of elastic tubing or is of the
spine and ribs configuration. Since the field strength required to
attract a ferromagnetic nanoparticle, microspherule, or miniball
dispersant will ordinarily result in pull-through or delamination
with stent failure, the use of a stent-jacket with shield is
substantially limited to highly sclerosed ductus. When directly
laminated to the underlyiing stent-jacket, the increased resilience
of combined layers must be taken into account, as must the breach
in shielding created by the slit and potential damage to the fine
vessels and nerves of the adventitia that may result from
ensheathment within a not otherwise perforated, `breathing`
restrictive if not eliminating covering that does not break down
with depletion of the radiation.
[1180] Atherosclerotic sequelae, for example, are avoided by using
an absorbable radiation shield that will break down spontaneously
or sooner by direction from outside the body. The underlying
stent-jacket itself perforated and slit, the interposition between
the outer surface of the stent-jacket and internal surface of the
encircling shield allows the stent-jacket an extent of movement
independently of the shield, providing a method for reducing
overall resilience other than changes in materials or thicknesses
of the layers. Since the gap between stent-jacket and shield allows
the stent-jacket to expand within, the shield can be bonded shut;
however, it still must be sufficiently pliant to allow encirclement
of the ductus. Newer open cell materials do allow gases to pass
through, but for the present application, do so to a practical
extent only when limited to cuffs toward the end margins,
interposed between the inner jacket and outer shield. For most
purposes here, closed cell material is preferable as minimizing
infiltration with blood, serous fluid, or tissue. At least in a
spine and ribs type stent-jacket, increasing the thickness of these
cuffs allows the ribs to move more freely and the adventitia to
breath.
[1181] Because the shield must be compliant, a stony, stiff, or
rigid monolithic structure can be used only when space permits the
interposition of a sufficient thickness of a sufficiently gas
permeable foam lining to accommodate movement intrinsic in the
substrate ductus. Then only may lithotripsy be used to effect
dissolution. The ability to limit exposure allows the use of higher
dose-rate seed miniballs or stays than might otherwise be
allowable. Absorption on demand is addressed below in the section
entitled Noninvasive Dissolution on Demand of Absorbable
Stent-jackets and Base-tubes, and applies no less to the matrix of
a radiation shield. The ability to segregably disintegrate a
radiation shield needed only until the radioactive seed miniballs
or stays decay such that the underlying stent-jacket lamina with
perforations can be exposed on demand is accelerated by means of
heat alternating magnetic or electromagnetic eddy current heat
induction is addressed below in the section entitled Noninvasive
Dissolution on Demand of Absorbable Stent-jackets, Base-tubes,
Radiation Shields, and Miniballs.
[1182] Radiation seed miniballs can be left in place when expended,
which always pertains when a stenting function is present as well,
or be retrieved endoluminally with the recovery electromagnets in a
barrel-assembly muzzle-head--usually the same barrel-assembly used
to place the miniballs--or extraluminally by means of an
extracorporeal electromagnet, both addressed herein. Stays are not
recovered, but except for the seed contained, can be absorbable.
The addition of shielding should least detract from the flexibility
or add to the thickness of the stent-jacket. Mass and thickness are
minimized by using the heaviest materials, such as tungsten, gold,
platinum, iridium, osmium, and platinum-osmium alloy, only the
elemental noble or nonreactive metals not requiring chemical
isolation encapsulation. Tungsten has the added advantage that when
placed in a radiofrequency alternating magnetic or electromagnetic
field, the shield can also be heated, whether to accelerate the
metabolic rate, healing, relieve discomfort, rate of drug release
and/or uptake, or the rate of prompt dissolution of the layer if
absorbable.
[1183] Heating can release bound water embedded within the layer
itself or that to which it is bonded. Lamina devised to
disintegrate or release medication are bonded to the base layer by
means of an adjesive. Lamina such as nonabsorbable radiation
shields not susceptible to degradation or disintegration by heating
can be bonded by any of a number of long established methods, to
include induction welding by doping the layer with a ferromagnetic
particulate and heating the layers in an induction furnace, for
example. Provided the particulate is chemically isolation-coated as
to remain such, the toxicity of these materials does not preclude
their use for radiation shielding when embedded within an
absorbable matrix layer. When not administered in the form of
powdered compounds, gold and platinum have the advantage of being
nonreactive or noble, hence, nontoxic. To allow flexibility
consistent with continuity, the protectively encapsulated particles
are embedded within the polymeric matrix in overlapping relation
within a nonresilient polymeric matrix.
[1184] The addition of a radiation shield, addressed above in the
section entitled System Implant Magnetic Drug and Radiation
Targeting, is by lamination to an existing stent-jacket. This
affords versatility, the alternative being the production of
special shielded quasi-intrinsic stent-jackets that include both
shielding and magnetized particulates, for example. Lamination is
to an intrinsically, quasi-intrinsically, or absorbable
quasi-intrinsically magnetized stent-jacket, lamination to a
stent-jacket with discrete magnets avoided as yielding unwanted
thickness. An absorbable radiation shield can be laminated to an
absorbable or a permanent stent-jacket that is to continue as a
stent, but an absorbable stent-jacket is always laminated with an
absorbable shield. Lamination is by adhesive bonding, methods such
as the use of heat or plastic welding usually inapplicable.
Radiation shielding is addressed below in the section entitled
Radiation Shielding Stent-jackets.
[1185] 8c. Placement of the Extraluminal Stent
[1186] 8c(1). Considerations as to Access
[1187] An advantage afforded by an ablation or angioplasty-capable
barrel-assembly being the capability to perform an ablation or
angioplasty without the need for withdrawal in order to stent,
points of entry are mentioned above in the section entitled
Comparison with Prior Art Angioplasty. Laparoscopic techniques have
made it possible to access vessels and ducts without extensive
incision, making the placement of stays and stenting that
necessitates local entry for circumvascular access less
objectionable than when more extensive exposure was necessary.
Rarities such as tunneling coronary arteries not amenable to being
dissected free excepted, practically any ductus can be
extraluminally stented; seldom if ever will a ductus or its sheath
be so closely surrounded by skeletal muscle or other tissue that an
intrinsically magnetized thin stainless steel or soft and
biocompatible polymer-coated stent-jacket or other extraluminal
implant described herein of smooth outer contour would result in
abrasion or encroachment.
[1188] Neither are most ductus unsuitably positioned or weak-walled
over a length such that the remedial measures to be described
herein cannot be applied. Dissection for circumvascular application
of a stent or impasse-jacket should seek to minimize compression or
abrasion of the adjacent tissue. Extraluminal stenting of the
trachea requires access by `keyhole` incision and of the bronchi by
`keyhole` thoracotomy or trephine sternotomy to place the
stent-jacket, which carries some risk (Walser, E. M. 2005. "Stent
Placement for Tracheobronchial Disease," European Journal of
Radiology 55(3):321-330) and is no less susceptible to bacterial
colonization (Noppen, M., Pierard, D., Meysman, M., Claes, I. and
Vincken, W. 1999. "Bacterial Colonization of Central Airways after
Stenting," American Journal of Respiratory and Critical Care
Medicine 1999 160(2):672-677). Luminal obstruction that results
purely from internal swelling, such as ashtma or bronchitis, is a
matter for medical management and not suitable for extraluminal
stenting, which should seldom if ever be used to distend a ductus
beyond its normal outer diameter. Also not targeted is the
bronchomalacia of infants, which seldom fails to resolve
spontaneously and does not justify percutaneous access.
[1189] However, where the condition involves collapse or weakening,
such as a persistent adult tracheomalacia (see, for example,
Kandaswamy, C. and Balasubramanian, V. 2009. "Review of Adult
Tracheomalacia and its Relationship with Chronic Obstructive
Pulmonary Disease," Current Opinion in Pulmonary Medicine
15(2):113-119; Murgu, S. D. and Colt, H. G. 2006. "Treatment of
Adult Tracheobronchomalacia and Excessive Dynamic Airway Collapse:
an Update," Treatments in Respiratory Medicine 5(2):103-115), an
extraluminal stent, because it leaves the lumen clear, will not
promote the development of granulation tissue that can bury an
endoluminal stent its precluding removal (Anton-Pacheco, J. L.,
Cabezali, D., Tejedor, R., Lopez, M., Luna, C., Comas, J. V., and
de Miguel, E. 2008. "The Role of Airway Stenting in Pediatric
Tracheobronchial Obstruction," European Journal of Cardiothoracic
Surgery 33(6):1069-1075, Section 3.3. Complications; Filler, R. M.,
Forte, V., and Chait, P. 1998. "Tracheobronchial Stenting for the
Treatment of Airway Obstruction," Journal of Pediatric Surgery
33(2):304-311) and should not interfere with respiratory epithelial
secretion and the immune function of the mucociliary
`escalator.`
[1190] To avert migration, endoluminal bronchial stents must have
posts, rings, or struts that protrude into and thus anchor or brace
the stent in the airway lining. Tracheal collapse can affect any
avian or mammalian species. Several are referenced in the section
below entitled Application of Simple Pipe-type Barrel-assembly to
the Magnetic Correction of Tracheal and Bronchial Collapse
(Veterinary). Valuable zoo specimens, livestock, and mammals kept
as pets are often the subjects of corrective procedures. Compared
to the extent and complexity of dissection required to place a
graft, that required to place an implant described herein is
slight. Access to the external surface of the ductus to be treated
is essential to apply a stent-jacket, stays, or a clasp-jacket.
[1191] About 27 percent of coronary arteries are surrounded by
muscle, the consequence for the development of atherosclerosis in
dispute (see, for example, Ishikawa, Y., Kawawa, Y., Kohda, E.,
Shimada, K., and Ishii, T. 2011. "Significance of the Anatomical
Properties of a Myocardial Bridge in Coronary Heart Disease,"
Circulation Journal 75(7):1559-1566; Saidi, H., Ongeti, W. K., and
Ogeng'o, J. 2010. "Morphology of Human Myocardial Bridges and
Association with Coronary Artery Disease," African Health Sciences
10(3):242-247; Ishikawa, Y., Akasaka, Y., Suzuki, K., Fujiwara, M.,
Ogawa, T., and 20 others 2009. "Anatomic Properties of Myocardial
Bridge Predisposing to Myocardial Infarction," Circulation
120(5):376-383; Duygu, H., Zoghi, M., Nalbantgil, S., Kirilmaz, B.,
Turk, U., Ozerkan, F., Akilli, A., and Akin, M. 2007. "Myocardial
Bridge: A Bridge to Atherosclerosis," [in English] Anadolu
Kardiyoloji Dergisi 7(1):12-16; Ishii, T., Asuwa, N., Masuda, S.,
and Ishikawa, Y. 1998. "The Effects of a Myocardial Bridge on
Coronary Atherosclerosis and Ischaemia," Journal of Pathology
185(1):4-9), tunneling considered to be anomalous remains
intramyocardial for more than 20 millimeters at a depth of greater
than 5 millimeters.
[1192] The arteries in the extremities are ensheathed and will
usually provide sufficient clearance to be encircled by at least a
very thin intrinsically magnetized stainless stent-jacket. Access
to the coronary arteries is through a small, typically less than 5
centimeter, left or right, third or fourth intercostal minimal port
or `keyhole` mini-thoracotomy (see, for example, Landreneau, R. J.,
Mack, M. J., Magovern, J. A., Acuff, T. A., Benckart, D. H.,
Sakert, T. A., Fetterman, L. S., and Griffith, B. P. 1996.
"Keyhole" Coronary Artery Bypass Surgery," Annals of Surgery
224(4).453-462), small or burr sternotomy, or ministernotomy.
Another angle of approach is directly through the sternum by means
of a craniotome or trephine (surgical hole saw). If necessary, an
accessory intercostal port is used for video assist. The one access
site allows both stays and a stent-jacket to be applied, so that
when preparatory treatment such as an angioplasty is excluded, the
artery is never entered; "direct stenting" is addressed above in
the section entitled Closer Comparison of Extraluminal to
Endoluminal, or Conventional, Stenting.
[1193] Anomylous arteries that course through muscle, specifically
submyocardial tunneling or `myocardial bridging` coronary arteries
(Alegria, J. R., Herrmann, J., Holmes, D. R. Jr., Lerman, A., and
Rihal, C. S. 2005. "Myocardial Bridging," European Heart Journal
26:1159-1168); Sundaram, B., Patel, S., Bogot, N., and Kazerooni,
E. A. 2009. "Anatomy and Terminology for the Interpretation and
Reporting of Cardiac MDCT: Part 1, Structured Report, Coronary
Calcium Screening, and Coronary Artery Anatomy," American Journal
of Roentgenology 192(3):574-583) should not be stent-jacketed.
However, these arteries appear not to exceed 12 percent (Ricciardi,
M. J., Beohar, N., and Davidson, C. J. 2005. "Cardiac Catherization
and Coronary Angiography," in Rosendorff, C. (ed.), Essential
Cardiology: Principles and Practice, Totowa, N.J.: Humana Press,
page 208), and with a radial projection catheter or barrel-assembly
containing sufficient radial projection units, can be angioplastied
and/or otherwise treated with any tool or therapeutic
substance.
[1194] For conditions that reduce the outer diameter of the ductus,
primarily tracheal or bronchial collapse, arterial shrinkage
(negative remodeling, contracture), and persistent localized
arterial vasospasm, the immediate advisability of applying outward
traction may warrant the placement of an extraluminal stent ab
initio. Access to place a stent of the kind described is less
traumatic than the open surgical procedure that must be performed
to place a tracheal extraluminal stent made of rings cut from an
injection syringe or to place a graft or stent-graft; however, it
is more traumatic than the transluminal delivery of an endoluminal
stent, which is, however, basically inferior.
[1195] 8c(2). Means for the Placement of the Stent-Jacket
[1196] The stent-jacket is placed through a laparoscopic entry
wound a few centimeters long. When the risk of injury to underlying
structures is higher, entry with a trocar should be avoided. Once
incised, a trocar can be inserted to retract the tissue surrounding
the incision. Existing surgical and microsurgical instruments are
not configured for expeditious placement of a stent-jacket and
require extension of the entry wound. For that reason, special hand
tools, described below in the section entitled Stent-Jacket
Insertion Tools, are provided. The same tools are used to place any
type stent or impasse-jacket.
[1197] 8d. Closer Comparison of Extraluminal to Endoluminal, or
Conventional, Stenting
[1198] Two critical distinctions between an endoluminal and an
extraluminal stent are that an extraluminal stent avoids the
numerous complications associated with sustained intrusion in the
lumen, and unlike the endoluminal stent, complies with movement or
muscular action in the wall of the ductus. The use of stays can
make it possible to avoid entry into the lumen entirely. In the
circulatory system, the problems produced by an endoluminal stent
include immune rejection and adverse tissue reaction responses to
the presence of alien matter, an initial immune followed by an
adaptation response to the obtrusive presence of a foreign object,
and misinterpretation by cytokines that the source of localized
tubrbulent flow represents a breach. With an extraluminal stent,
the dyslipidemia associated with the atherosclerosis will continue
to require the use of a statin, but anticoagulative medication need
not be taken for life.
[1199] Where an endoluminal stent must exert radially outward force
to prevent migration, an extraluminal stent provides radially
inward support of the already diseased ductus, which may
additionally have undergone an atherectomy or angioplasty, further
weaking it. In an artery, this can be the difference between
encouraging and preventing aneurysmal failure. Situated outside the
lumen, an extraluminal stent avoids the clogging, migration, loss,
fracture, deformation, and other hazards that persist with the use
of endoluminal stents and guidewires (references below). When a
preparatory angioplasty is waived, stays eliminate the need for
entry into the lumen altogether. Once implanted along the vascular
tree, an extraluminal stent averts thrombogenic disruption to the
streamline or laminar flow of blood and chronic irritation as
induces in-stent restenosis.
[1200] Balloon expansion not preceded by in situ testing, the
endoluminal stent affords slight if any ability to adjust the force
of patenting restraint to that least necessary. Diseased or healing
tissue is intruded upon by a hard and noncompliant scaffold that
protrudes into, stretches, and irritates it. An endoluminal stent
always protrudes into the intima and can even protrude into tissue
surrounding the ductus. When this results in chronic irritation as
sustained pressure or tissue on tissue rubbing, an erosive lesion
or fistula can form. Endoluminal stents in adjacent relation, such
as segments of the trachea and the esophagus, are infrequently
required, but can place the structures in a rubbing and erosive
relation. By contrast, extraluminal stent-jackets in adjacent
relation can no more than rub against one another, each enclosing
its responective substrate adventitia, holding it at a distance
from its neighbor, and thus preventing abrasion.
[1201] Additional hazards include deformation, fracture, and
migration, all more likely should the stent incur an accidental
impact. Regardless of the cause, protracted impairment in
physiological function due to chronic immobilization of the
treatment site (motional interference, motile suppression) induces
a tissue reaction, first of immune rejection, then of adaption, and
destroys normal structure and function in the lumen wall. Even
though the smooth muscle had deteriorated or atrophied, a stent
that is able to comply in expandability and contractility can be
significant in preserving residual vascular physiology, and if
sufficient, even promote recovery. In any ductus, the fact that no
foreign object occupies the lumen means that the passage of
contents is less if at all impeded and the mechanics of the wall
little if at all affected.
[1202] In end to end anastomotic tuboplasty, for example, where an
endoluminal stent can migrate (see, for example, Jurema, M. W. and
Vlahos, N. P. 2003. "An Unusual Complication of Tubal Anastomosis,"
Fertility and Sterility79(3):624-627) and plain
polytetrafluoroethylene tubing may be used as an endoluminal stent
(see, for example, Roland, M. and Leisten, D. 1977. "Advances in
Tuboplasty," Acta Obstetricia et Gynecologica Scandinavica
56(4):419-426), or following balloon tuboplasty where swelling that
would obstruct the lumen is prevented by placing a stent (see, for
example, Kerin, J. F. and Surrey, E. S. 1992. "Tubal Surgery from
the Inside Out: Falloposcopy and Balloon Tuboplasty," Clinical
Obstetrics and Gynecology. 35(2):299-312), the reinstatement of
normal function at every level to include peristalsis, much less
the recovery of fertility, remains impossible until the endothelium
overlying and rigid tubing is removed, whereupon swelling and
constriction might occur or reoccur.
[1203] By contrast, an extraluminal stent leaves the lumen free and
clear and can be left in place to preserve patency indefinitely.
Where an antecedent procedure that interrupted fertility was
uninvolved, as in the treatment of salpingitis or a tuboovarian
abcess where the chance of obstruction is a concern, an
extraluminal stent in conjunction with the administration of
antibiotics does not disrupt ovarian steroid production that can
reduce swelling and improves the odds for preserving fertility
(Wiesenfeld, H. C and Sweet, R. L. 1993. "Progress in the
Management of Tuboovarian Abscesses," Clinical Obstetrics and
Gynecology.36(2):433-444; Akyol, D., Ozcan, U., Ekin M., Gungor,
T., and Gokmen, O. 1998. "Tubo Ovarian Abscess: Risk Factors and
Clinical Features in Turkish Population," Turkish Journal of
Medical Sciences 28:691-692). The intraductal component of the
extraluminal stent can consist of or include stays or miniballs
that incorporate medication and/or irradiating seeds to treat the
lesion and maintain patency.
[1204] Even if not significantly injured, angioplasty in itself
stimulates the proliferation of smooth muscle cells in and
infiltration of leukocytes into the media, and endoluminal stenting
induces inflammation that predisposes toward in-stent lesion
development (Miyahara, T., Koyama, H., Miyata, T., Shigematsu, H.,
Inoue, J., Takato, T., and Nagawa, H. 2006. "Inflammatory Responses
Involving Tumor Necrosis Factor Receptor-associated Factor 6
Contribute to In-stent Lesion Formation in a Stent Implantation
Model of Rabbit Carotid Artery," Journal of Vascular Surgery
43(3):592-600).
[1205] With an extraluminal stent, in-stent restenosis as the
result of the same forces impossible. Leaving the lumen clear, an
extraluminal stent used in place of an endoluminal stent following
an angioplasty that resulted in a dissection, for example, tends
less to induce proliferative or thrombogenic sequelae as contribute
to the need for, complicate, and interfere with retreatment for
restenosis. When the extraluminal stent uses stays, which are
inserted from outside of the ductus and through the adventitia or
fibrosa, the avoidance of contact with the inner surface of the
lumen wall leaves the endothelium substantially if not completely
intact. An extraluminal stent poses no obstruction to any later
transluminal procedure. An extraluminal stent in the airway or
gastrointestinal tract cannot accumulate detritus.
[1206] The recovery of an endoluminal stent that has migrated,
fractured, or is repeatedly clogged or lined with accreted matter
or detritus is seldom practicable (see, for example, Liermann, D.
and Kirchner, J. 2004. "Foreign Body and Stent Retrieval," Chapter
26 in Heuser, R. R. and Henry, M., Textbook of Peripheral Vascular
Interventions, London, England: Informa Health Care; Almeida, R. M.
S. de, Bastos, L. C., Lima, J. D. Jr., and Jorge, A. C. 1997.
""Retrieval of a Migrated Coronary Stent by Cardiopulmonary
Bypass," Internet Journal of Thoracic and Cardiovascular Surgery
2(1):18). Instead, when necessary, the stent is repositioned and
fixed in place with a second stent (see, for example, Meisel, S. R,
DiLeo, J., Rajakaruna, M., Pace, B., Frankel, R., and Shani, J.
2000. "A Technique to Retrieve Stents Dislodged in the Coronary
Artery Followed by Fixation in the Iliac Artery by Means of Balloon
Angioplasty and Peripheral Stent Deployment," Catheterization and
Cardiovascular Interventions 49(1):77-81), thus further aggravating
normal function.
[1207] Avoiding the need for extraductal access, endoluminal stents
are more widely applicable than are extraluminal stents and involve
less trauma to place; however, endoluminal stents, especially in
the ureters, for example, are short-lived, obstructive, smooth
muscle-restraining, endothelium and lamina propria irritants, hence
palliative, but only at considerable expense. For the purpose of
implanting medication-eluting or irradiating seed miniballs or
stays and/or stays as buttresses within the wall of a lumen where
the need for an extraluminal component or stent-jacket does not
exist, location of a lesion that precludes encirclement by a
stent-jacket or patch-magnets does not limit use of the means
described. To prevent migration, any endoluminal stent, to include
those absorbable pending absorption, must exert radially outward
force over the entire circumference. This precludes the design
latitude essential to configure the stent to accommodate lesion
eccentricities as well as interferes with endothelial function.
[1208] Neither do endoluminal absorbable stents allow preventive
use by allowing preplacement at points where reocclusion is likely
to ensue due to cellular proliferation despite the use of a statin
drug, such as bifurcations in the arterial tree (see, for example,
Koutouzis, M., Paraskevas, K. I., Rallidis, L. S., Barbatis, C.,
Nomikos, A., and 7 others 2008. "Statin Treatment, Carotid
Atherosclerotic Plaque Macrophage Infiltration and Circulating
Inflammatory Markers," Open Cardiovascular Medicine Journal
2:110-114; Shukla, A., Sharma, M. K., Jain, A., and Goel, P. K.
2005. "Prevention of Atherosclerosis Progression Using Atorvastatin
in Normolipidemic Coronary Artery Disease Patients--A Controlled
Randomized Trial," Indian Heart Journal 57(6):675-680; Nicolaides,
A., Beach, K. W., Kyriacou, E., and Pattichis (eds.) 2012.
Ultrasound and Carotid Bifurcation Atherosclerosis, London,
England: Springer; Suri, J. S., Kathuria, C., and Molinari, F.
(eds.) 2010. Atherosclerosis Disease Management, New York, N.Y.:
Springer), or where a progressive condition of collapse is
encountered, such as in the airway, as addressed below in the
section entitled Magnetic Correction of Airway Collapse and
described beginning with the section below entitled Treatment of
Tracheal Collapse in the Cervical Segments, i.e., Cephalad, or
Anterior, to the Thoracic Inlet.
[1209] The need for stenting substantially pertinent to ductus with
an exclusive supply territory (without collateral circulation)
where magnetic stenting is uninvolved so that the application of a
circumvascular stent-jacket is not required, stays can be used
regardless of the lumen diameter, and miniballs can be implanted
within any ductus large enough to admit the barrel-assembly. The
ductus-intramural implants leave the lumen clear, and when placed
for stenting, are attracted radially outward or centrifugally by a
magnetic field no stronger than is necessary to maintain patency.
Coating the internal or adluminal surface of the stent-jacket with
a surgical cement is unnecessary and discouraged as immobilizing.
The use of cements for other nonimmobilizing purposes is addressed
below under such sections as that entitled Sealing of Stay
Insertion Incisions with Cyanoacrylate Cement, and the use of
protein solders below under the section entitled Use of Solid
Protein Solder.
[1210] Whether congenital or the result of dissection or infection,
for example, eccentric lesions other than atheromatous, can also
appear in any ductus or blood vessel (see, for example, Russo, C.
P. and Smoker, W. R. 1996. "Nonatheromatous Carotid Artery
Disease," Neuroimaging Clinics of North America 6(4):811-830).
Numerous conditions prompt hyperplasia, and previous radiotherapy
or chemotherapy can induce hardening. Fluid infiltration,
hypervascularization, atrophy, and pyogenic arteritis can produce
malacia (softening). All of these alterations tend to be radially
asymmetrical, or eccentric. The neovascularized artery is usually
eccentric (see, for example, Hayden, M. R. and Tyagi, S. C. 2004.
"Vasa Vasorum in Plaque Angiogenesis, Metabolic Syndrome, Type 2
Diabetes Mellitus, and Atheroscleropathy: A Malignant
Transformation," Cardiovascular Diabetology 4;3:1). In fact,
different type lesions in differernt type ductus, to include
atheromatous and neoplastic, before and after treatment, tend to be
radially asymmetrical, or eccentric, with the ductus wall variable
in tenderness and strength about the circumference.
[1211] Diseased tissue tending toward eccentricity, an improved
stent should allow eccentricities to be dealt with in a
discriminate manner. Unlike endoluminal stents, extraluminal stents
can accommodate side branches, attachments, and lesions which are
eccentric, as is usually the case. Unless intracranial or otherwise
denying circumvascular clearance, the vessel will be accessible to
encirclement with a stent-jacket. Furthermore, continuous
variability characterizing diseased tissue, the need for in situ
testing to evaluate the puncture and penetration resistance of the
lesion in the patient is clear. An improved stent should also
provide the means to test the mechanical properties of lesions.
Testing methods and apparatus are addressed below in the section
entitled Testing and Tests. The turret-motor allowing immediate
change in the rotational angle of the muzzle-head and thus rotation
of the exit-port or ports, and the rotary magazine clip instantly
changed to blank out any barrel-tube or tubes and thus arc,
eccentric lesions are readily avoided or implanted with
miniballs.
[1212] This remains the case even with lesions that change in
circumferential placement longitudinally, that is, spread to or
recede from the adjacent arcs from segment one segment or level to
the next. Muzzle-heads with muzzle-ports separated by less than 45
degrees are therefore not only unchangeable midprocedurally without
withdrawal and reentry but nonessential. Vessels too small in gauge
to admit a multibarrel barrel-assembly are negotiated with a radial
discharge monobarrel equipped with a turret-motor. With an imaging
technique that allows distinguishing arcs about the lumen, the
angioplasty, atherectomy, and implantation means provided herein
complement these capabilities. Leaving the lumen clear, an
extraluminal stent affords discriminatory treatment of eccentric
lesions both during angioplasty or atherectomy and any subsequent
therapy.
[1213] The magnetic extraluminal stents described herein differ
from endoluminal stents not only in the ability to include or avoid
areas about the lumen in an absolute sense, but in the ability to
apply differential patenting force (magnetic field strength) to
different arcs at different levels; an magnetic extraluminal stent
can apply tractive force asymmetrically both longitudinally and
circumferentially. Such can serve to increase the retractive force
acting upon a stricture with the strength to retain the
ductus-intramural implants, or to minimize irritation to diseased
or healing tissue. This is accomplished simply by varying the
ferromagnetic content or number of the implants and/or the
strengths or number of the magnets about the base-tube. Depending
upon the pattern of the lesions and lumen wall strength, limited
areas of the wall can be omitted from subjection to a tractive
patenting force if increasing the force on neighboring areas will
serve to maintain patency. Strength pattern coordinated
ductus-intramural implants and stent-jackets asymmetical with
respect to magnetic strength are marked to assure proper
orientation.
[1214] Eccentric and pathologically distinct lesions within the
same vessel or duct can also be dealt with through the use of
differently medicated or irradiative miniball implants. Eccentric
and pharamacologically differential treatment can usually be
accomplished without the need to withdraw one barrel-assembly and
replace it with another having a differently configured
muzzle-head. Not only does this reduce procedural time, but the sum
duration of transient ischemia due to blockage of the vessel by the
apparatus and of injury to the inguinal or brachial point of entry
is significantly reduced. Whereas endoluminal stenting imposes some
clotting for endothelial recovery, stays avoid the lumen. Properly
inserted stays produce no endothelial injury or exposure of
collagen that leads to scarring. An endoluminal stent, especially
one with a bare metal surface, facilitates the thrombogenicity
associated with any antecedent angioplasty that resulted in a
dissection of the lumen wall, additionally promoting intimal
hyperplasia and constrictive remodelling.
[1215] An endoluminal stent in the airway or the esophagus can
serve as a scaffold for the spread of infection; the stent
accumulates detritus, and if protruding into, chronically
irritating, and thus eventually breaking through the lumen lining,
will inoculate the lumen wall. Sterile miniballs and stays
implanted subadventitiously or subfibrosally under sterile
conditions will cannot act to spread infection. The means described
herein necessitate the administration of clot-preventing medication
(platelet blockade); however, without a metal object left within
the lumen, the duration for such treatment is much shorter.
Absorbable endoluminal stents avoid protracted thrombogenicity also
but should not be used for combined or single pass stenting
angioplasty, and cannot be used to prevent stenoses at locations
where these can be anticipated, as addressed below in this
section.
[1216] In contrast to an endoluminal stent, a circumvascular
elastic stent that complies with changes in caliber of the
substrate vessel or duct wthout compressing the adventitia is not a
constant source of irritation. Especially for vasculopathy that
calls for stenting alone, extraluminal stenting, because it leaves
the lumen clear, is less susceptible to adverse sequelae. The
measures employed to avert embolism are discussed below. The
typically submillimetric, sometimes no larger than 0.4 millimeter
or 400 micrometer trajectories of miniballs quickly seal and
quickly heal, and even though recommending the short-term
administration of anti-platelet agents and anti-coagulants, do not
represent a source of continued irritation or thrombogenicity.
Necessarily depending upon the dimensions of the ductus where
potential applications encompass those pediatric and veterinary,
those in the vascular tree, the airway, and the gastrointestinal
tract, estimated in the abstract, miniballs, for example, can range
in diameter anywhere from around 0.1 to 4.0 millimeters.
[1217] Stenting of the superior vena cava that avoids the lumen
without encroaching upon the ascending aorta, for example, can
avert the adverse sequelae of endoluminal stenting, to include
aortic perforation, migration, reocclusion (Kappert, U., Schulz, C.
G., Waldow, T., Tugtekin, S. M., Alexiou, C., and Matschke, K.
2006. "Perforation of the Ascending Aorta: A Late Complication of
Superior Vena Cava Stenting," Thoracic and Cardiovascular Surgeon
54(1):63-65), albeit rare, pericardial tamponade (Martin, M.,
Baumgartner, I., Kolb, M., Triller, J., and Dinkel, H. P. 2002.
"Fatal Pericardial Tamponade after Wallstent Implantation for
Malignant Superior Vena Cava Syndrome," Journal of Endovascular
Therapy 9(5):680-684), and similar injuries (Recto, M. R.,
Bousamra, M., and Yeh, T. Jr. 2002. Late Superior Vena Cava
Perforation and Aortic Laceration after Stenting to Treat Superior
Vena Cava Syndrome Secondary to Fibrosing Mediastinitis," Journal
of Invasive Cardiology 14(10):624-629).
[1218] While inflammation is often pan-arteritic (see, for example,
Higuchi, M. L., Gutierrez, P. S., Bezerra, H. G., Palomino, S. A.,
Aiello, V. D., Silvestre, J. M., Libby, P., Ramires, J. A. 2002.
"Comparison Between Adventitial and Intimal Inflammation of
Ruptured and Nonruptured Atherosclerotic Plaques in Human Coronary
Arteries," Arquivos Brasileiros Cardiologia 79(1):20-24), and prior
to atherectomy, adventitial inflammation might conceivably
contribute to plaque instability (see, for example, Hu, C L ,
Xiang, J. Z., Hu, F. F., and Huang, C. X. 2007. "Adventitial
Inflammation: A Possible Pathogenic Link to the Instability of
Atherosclerotic Plaque," Medical Hypotheses 68(6):1262-1264),
avoidance of the lumen eschews the many additional complications
that may arise within the lumen and is advantageous in certain
conditions that involve inflammation of the intima, such as
Takayasu disease (Takayasu arteritis, brachiocephalic arteritis,
Martorell;'s syndrome, reversed coarctation, pulseless disease,
aortic arch syndrome, occlusive thromboaortopathy) when in-stent
restenosis could otherwise pose a problem (Mieno, S., Horimoto, H.,
Arishiro, K., Negoro, N., Hoshiga, M., Ishihara, T., Hanafusa, T.,
and Sasaki, S. 2004. "Axillo-axillary Bypass for in-Stent
Restenosis in Takayasu Arteritis," International Journal of
Cardiology 94(1):131-132) and antiphospholipid (Hughes) syndrome
(see, for example, Ben-Ami, D., Bar-Meir, E., and Shoenfeld, Y.
2006. "Stenosis in Antiphospholipid Syndrome: A New Finding with
Clinical Implications," Lupus 15(7):466-472).
[1219] Outside the lumen. not interfering with flow-through and
little if at all with motility, an extraluminal stent in the gut,
unlike an endoluminal stent, does not serve as a scaffold for the
accumulation if not accretion of debris, and outside the forceful
contractive waves, is inherently less susceptible to migration
(Suzuk,i N., Saunders, B. P., Thomas-Gibson, S., Akle, C.,
Marshall, M., and Halligan, S. 2004. "Colorectal Stenting for
Malignant and Benign Disease: Outcomes in Colorectal Stenting,"
Diseases of the Colon and Rectum 47(7):1201-1207). End-ties,
end-straps, and sectional stent-jackets increase resistance to
displacement. The advantage in an absorbable stent being that it
does not remain as a permanent irritant and cause of adverse
sequelae, no endoluminal stent is suited to preventing stenoses at
locations where the appearance of a threatening lesion can be
anticipated.
[1220] The ability to do so is of long standing, based upon such
factors as hemodynamic sheer stress (see, for example, Malek, A.
M., Alper, S. L., and Izumo, S. 1999. "Hemodynamic Shear Stress and
Its Role in Atherosclerosis," Journal of the American Medical
Association 282(21):2035-2042; Malek, A. M. and Izumo, S. 1995.
"Control of Endothelial Cell Gene Expression by Flow," Journal of
Biomechanics 28(12):1515-1528; Hugh, A. E. and Fox, J. A. 1970.
"The Precise Localisation of Atheroma and Its Association with
Stasis at the Origin of the Internal Carotid Artery--A Radiographic
Investigation," British Journal of Radiology 43(510):377-383) and
wall structure (see, for example, Langheinrich, A. C., Michniewicz,
A., Bohle, R. M., and Ritman, E. L. 2007. "Vasa Vasorum
Neovascularization and Lesion Distribution Among Different Vascular
Beds in ApoE-/-/LDL-/- Double Knockout Mice," Atherosclerosis
191(1):73-81; Tracy, R. E. 2005. "Evidence Concerning Resistance to
Atheroma by Media-like Islands in the Intima of Coronary Arteries,"
Atherosclerosis 178(1):49-56).
[1221] Current absorbable stents also tend to lack adequate
strength and disintegrate too slowly, restenosis rates are high,
and making these drug-eluting will likely result in additional
endothelial dysfunction. Whereas endoluminal stents are placed
transluminally with only one entry portal required, the
extraluminal stents to be described require direct access to the
treatment site to place stays and the stent-jacket. Where a
preliminary ablation or angioplasty is not performed, those using
stays involve no transluminal component and require no separate
radial, brachial, or femoral entry. Those that use miniball
implants require both transluminal access and separate direct entry
through a small incision and dissection to allow the vessel or duct
to be mantled about with the stent-jacket, clasp-jacket, or
impasse-jacket.
[1222] Extraluminal stenting is unintended for use with ductus
invested within tissue, such as the pancreatic duct or an
anomalously submyocardial coronary artery that courses (tunnels,
bridges) through muscle. However, ablation and ablation and
angioplasty-capable barrel-assemblies can be used to ablate or
atherectomize, and/or implant medication or irradiating seeds
within the walls of ductus however intimately surrounded by tissue.
When more distantly mounted patch or clasp-magnets or a
magnet-jacket, as addressed below in sections of like title, cannot
be used, an endoluminal stent must be used instead.
[1223] The uncomplicated placement of an extraluminal stent
initially imposes more trauma than does the uncomplicated insertion
of a properly sized endoluminal stent; however, this trauma heals
quickly, and once placed, the extraluminal stent remains
substantially risk-free. Improved outcomes can justify incisional
over transluminal procedures (see, for example, Derksen, W. J.,
Gisbertz, S. S., Pasterkamp, G., De Vries, J. P., and Moll, F. L.
2008. "Remote Superficial Femoral Artery Endarterectomy," Journal
of Cardiovascular Surgery (Turin, Italy) 49(2):193-198). By
contrast, the trauma associated with the placement of an
endoluminal stent consists of injury to the intima; however, if the
long-term prognosis is essentially the same, the ability to avoid
surgery is an advantage.
[1224] The trauma of inserting an extraluminal stent consists of
the small incision and dissection to gain access to the tunica
fibrosa or adventitia of the ductus to be stented, and injury,
rarely significant, to the periductal vasculature and
innervation--in blood vessels, the vasa and nervi vasora, which
will usually be too profuse, dispersed, and obscured to avoid
completely, especially since the vasa vasorum of a diseased vessel
is likely to have become elaborated through neovascularization
(see, for example, Di Stefano, R., Felice, F., and Balbarini, A.
2009. "Angiogenesis as Risk Factor for Plaque Vulnerability,"
Current Pharmaceutical Design 15(10):1095-1106; Doyle, B. and
Caplice, N. 2007. "Plaque Neovascularization and Antiangiogenic
Therapy for Atherosclerosis," Journal of the American College of
Cardiology 49(21):2073-2080; Jain, R. K., Finn, A. V., Kolodgie, F.
D., Gold, H. K., and Virmani, R. 2007. "Antiangiogenic Therapy for
Normalization of Atherosclerotic Plaque Vasculature: A Potential
Strategy for Plaque Stabilization," Nature Clinical Practice.
Cardiovascular Medicine 4(9):491-502; Ritman, E. L. and Lerman, A.
2007. "The Dynamic Vasa Vasorum," Cardiovascular Research
75(4):649-658; Moreno, P. R., Purushothaman, K. R., Zias, E., Sanz,
J., and Fuster, V. 2006. "Neovascularization in Human
Atherosclerosis," Current Molecular Medicine 6(5):457-447; Virmani,
R., Kolodgie, F. D., Burke, A. P., Finn, A. V., Gold, H. K.,
Tulenko, T. N., Wrenn, S. P., and Narula, J. 2005. "Atherosclerotic
Plaque Progression and Vulnerability to Rupture: Angiogenesis as a
Source of Intraplaque Hemorrhage," Arteriosclerosis, Thrombosis,
and Vascular Biology 25(10):2054-2061; Heistad, D. D. and
Armstrong, M. L. 1986. "Blood Flow Through Vasa Vasorum of Coronary
Arteries in Atherosclerotic Monkeys," Arteriosclerosis
6(3):326-331).
[1225] Since at least 1996, the application of an external stent
has been known to reduce intimal thickening in vein grafts (Izzat,
M. B., Mehta, D., Bryan, A. J., Reeves, B., Newby, A. C., and
Angelini, G. D. 1996. "Influence of External Stent Size on Early
Medial and Neointimal Thickening in a Pig Model of Saphenous Vein
Bypass Grafting," Circulation 94(7):1741-1745; Angelini, G. D.,
Izzat, M. B., Brya,n A. J., and Newby, A. C. 1996. "External
Stenting Reduces Early Medial and Neointimal Thickening in a Pig
Model of Arteriovenous Bypass Grafting," Journal of Thoracic and
Cardiovascular Surgery 112(1):79-84; Vijayan, V., Shukla, N.,
Johnson, J. L., Gadsdon, P., Angelini, G. D., Smith, F. C., Baird,
R., and Jeremy, J. Y. 2004. "Long-term Reduction of Medial and
Intimal Thickening in Porcine Saphenous Vein Grafts with a
Polyglactin Biodegradable External Sheath," Journal of Vascular
Surgery 40(5):1011-1019; Jeremy, J. Y., Bulbulia, R., Johnson, J.
L., Gadsdon, P., Vijayan, V., Shukla, N., Smith, F. C., and
Angelini, G. D. 2004. "A Bioabsorbable (Polyglactin),
Nonrestrictive, External Sheath Inhibits Porcine Saphenous Vein
Graft Thickening," Journal of Thoracic and Cardiovascular Surgery
127(6):1766-1772. The effect is probably due to structural
reinforcement by the stent of the graft vessel wall, which
eliminates the need for adaptive strengthening by proliferation of
smooth muscle cells.
[1226] Such external stents, absorbable or simple tubes that are
usually made of woven polyethylene terephthalate (polyester,
Terylene.RTM., Dacron.RTM.), are fundamentally different than the
stent-jackets described herein, and none of the claims appended
hereto would read upon any such prior art device. Prior art
external stents, some absorbable, are inwardly restraining but not
lumen-patenting, and those made of solid plastic tubing are
incapable of adapting to and remaining with the substrate ductus
while complying with its autonomic movement during overall
enlargement (expansion) or reduction (contraction). By contrast,
the extraluminal stents to be described are elastic and restrained
inwardly, in minimal diameter, while compliant outwardly.
[1227] Specifically, such a stent girds about an artery at its
diastolic (narrowest, quiescent) diameter and complies with, that
is, expands in response to, the outward force exerted by the pulse.
In the esophagus and gut, a special spine and ribs or reach-around
arms configured stent-jacket as described above in the sections
entitled Concept of the Extraluminal Stent, Spine and Ribs Type
Stent-jackets, and The Extraductal Component of the Extraluminal
Stent and the Means for its Insertion is matched in diameter to the
guage of the ductus when contracted but expands to the larger
quiescent diameter and even that of an expanding bolus without
physiologically significant resistance. The outward retractive
force imposed by the stent is easily overcome by that of the
peristaltic waves that pass therethrough.
[1228] However, in structure, function, and application, the
circumductal (periductal), specifically venous as well as arterial
circumvascular (perivascular, periductal) stents to be described
herein are fundamentally different from the various cuffs and
sheaths to which similar terminology has been applied in the past
(see, for example, Zou, R. J., Zou, L. J., Huang, S. D., Wang, Y.,
Han, L., Ji, G. Y., and Xu, Z. Y. 2007. "Effect of External Stents
on Prevention of Intimal Hyperplasia in a Canine Vein Graft Model,"
Chinese Medical Journal (in English) 120(24):2264-2267; Izzat, M.
B., Teng, Z. Z., Ji, G. Y., Chu, H. J., Li, Z. Y., Zou, L. J., Xu,
Z. Y., and Huang, S. D. 2007. "Does PGA External Stenting Reduce
Compliance Mismatch in Venous Grafts?," Biomedical Engineering
Online 6:12; Jeremy et al. 2004 cited above; Izzat et al. 1996
cited above; Froehlich, P., Seid, A. B., Kearns, D. B., Pransky, S.
M., and Morgon, A. 1995. "Use of Costal Cartilage Graft as External
Stent for Repair of Major Suprastomal Collapse Complicating
Pediatric Tracheotomy," Laryngoscope 105(7 Part 1):774-775).
[1229] While free to expand and contract and thus comply with
pulsatile and vasotonic-autonomic-renin-angiotensin system
regulated changes in gauge, the elastic circumvascular
stent-jacket, in marked contrast to a conventional endoluminal
stent, is not susceptible to deformation with possible migration,
deformation or ensuing migration induced abrupt closure and
infarction (see, for example, Nakahara, T., Sakamoto, S., Hamasaki,
O., and Sakoda, K. 2003. "Double Wire Technique for Intracranial
Stent Navigation," Journal of Vascular and Interventional Radiology
14(5):667-668), and thrombogenesis from an impact, the intromission
of a catheter (Brilakis, E. S., Roesle, M., and Banerjee, S. 2007.
"Stent Deformation after Catheter Advancement through a Recently
Deployed Self-expanding Stent: Diagnosis, Mechanism and
Correction," Journal of Invasive Cardiology 19(1):46), or during
balloon expansion if not spontaneously following placement
(Yallampalli, S., Zhou, W., Lin, P. H., Bush, R. L., and Lumsden,
A. B. 2006. "Delayed Deformation of Self-expanding Stents after
Carotid Artery Stenting for Postendarterectomy Restenoses," Journal
of Vascular Surgery 44(2):412-415; Rosenfield, K., Schainfeld, R.,
Pieczek, A., Haley, L., and Isner, J. M. 1997. "Restenosis of
Endovascular Stents from Stent Compression," Journal of the
American College of Cardiology 1997 29(2):328-338; Johnson, S. P.,
Fujitani, R. M., Leyendecker, J. R., and Joseph, F. B. 1997. "Stent
Deformation and Intimal Hyperplasia Complicating Treatment of a
Post-carotid Endarterectomy Intimal Flap with a Palmaz Stent,"
Journal of Vascular Surgery 25(4):764-768). Extraluminal, a
stent-jacket can be flexible and compliant in any length, can be
varied in thickness from end to end or side-slit edge to side-slit
edge, or can be varied thus by heat treatment, meaning mold-shape
biased to provide flexibility or compliance that is nonuniform or
eccentric even through curves.
[1230] Implantation with stays avoids the lumen entirely. A recent
trend favoring stenting without a preceding angioplasty ("direct
stenting") (see, for example, Kiemeneij, F, Serruys P W, Macaya C,
Rutsch W, Heyndrickx G, and 10 other authors, 2001. "Continued
Benefit of Coronary Stenting Versus Balloon Angioplasty: Five-year
Clinical Follow-up of Benestent-I Trial," Journal of the American
College of Cardiology 37(6):1598-1603; Versaci, F., Gaspardone, A.,
Tomai, F., Proietti, I., Ghini, A. S., Altamura, L., And , G.,
Crea, F., Gioffre, P. A., and Chiariello, L. 2004. "A Comparison of
Coronary Artery Stenting with Angioplasty for Isolated Stenosis of
the Proximal Left Anterior Descending Coronary Artery: Five Year
Clinical Follow-up," Heart 90(6):672-675; Versaci, F., Gaspardone,
A., Tomai, F., Crea, F., Chiariello, L., and Gioffre, P. A. 1997.
"A Comparison of Coronary-artery Stenting with Angioplasty for
Isolated Stenosis of the Proximal Left Anterior Descending Coronary
Artery," New England Journal of Medicine 336(12):817-822) minimizes
if it does not eliminate endothelial injury, and would be enhanced
were the transluminal step eliminated entirely. Minimizing the
number of passes through the entry wound reduces operating time and
probably the potential for injury to the endothelium and irritation
of the access wound (see, for example, Archbold, R. A., Robinson,
N. M., Schilling, R. J. 2004. "Radial Artery Access for Coronary
Angiography and Percutaneous Coronary Intervention," British
Medical Journal 329(7463):443-446).
[1231] 8e. Accommodation of the Adventitial Vasculature,
Innervation, and Perivascular Fat
[1232] Larger ductus may have an adventitial vasculature that must
not be constricted or injured longer than would quickly recover.
The coronary arteries in particular, have vasa vasora that
centrally implicated in the development of atherosclerosis and
atherothrombosis (see, for example, Langheinrich, A. C,
Kampschulte, M., Buch, T., and Bohle, R. M. 2007. "Vasa Vasorum and
Atherosclerosis--Quid novi?," Thrombosis and Haemostasis
97(6):873-879; Langheinrich, A. C., Michniewicz, A., Sedding, D.
G., Walker, G., Beighley, P. E., Rau, W. S., Bohle, R. M., and
Ritman, E. L. 2006. "Correlation of Vasa Vasorum Neovascularization
and Plaque Progression in Aortas of Apolipoprotein
E(-/-)/Low-density Lipoprotein(-/-) Double Knockout Mice,"
Arteriosclerosis, Thrombosis, and Vascular Biology 26(2):347-352),
must be accommodated and not induced to perpetuate disease through
compression by a continuous collar.
[1233] Perivascular fat, support vasa and nervora of which the
function is essential to the health of the substrate ductus is
avoided through the use of a small segmented or spine and ribs type
stent-jacket. This way, only so much of the surrounding tissue as
is necessary to gain thickness and hardenable tissue for
ductus-intramural implantation is included with the ductus in the
stent. Perivascular fat appears to be essential to normal
endothelial function but harmful when excessive (Szasz, T. and
Webb, R. C. 2012. "Perivascular Adipose Tissue: More than Just
Structural Support," Clinical Science (London) 122(1):1-12; Miao,
C. Y. and Li, Z. Y. 2012. "The Role of Perivascular Adipose Tissue
in Vascular Smooth Muscle Cell Growth," British Journal of
Pharmacology 165(3):643-658; Lu, C., Su, L. Y., Lee, R. M., and
Gao, Y. J. 2010. "Mechanisms for Perivascular Adipose
Tissue-mediated Potentiation of Vascular Contraction to
Perivascular Neuronal Stimulation: The Role of Adipocyte-derived
Angiotensin II," European Journal of Pharmacology 634(1-3):107-112;
Payne et al. Op cit., section above entitled Field of the
Invention; Gao, Y. J. 2007. "Dual Modulation of Vascular Function
by Perivascular Adipose Tissue and Its Potential Correlation with
Adiposity/Lipoatrophy-related Vascular Dysfunction," Current
Pharmaceutical Design 13(21):2185-2192).
[1234] For a defined segment, the relative contribution to
endothelial function by periadventital fat as a sum over the
arterial tree and that local to the segment longitudinally and
radially has not been defined. In this circumstance, a coronary
artery heavily invested in fat is dissected free of all the fat but
that proximate before jacketed. The difficulty of access due to
tunneling, adhesions, or a lack of clearance, and the extent of
dissection allowed must rest upon clinical judgment. In an elderly
patient, the expediency of endoluminal stenting will normally
override the object of imparting better function over the long
term. To expedite placement by eliminating prominences of
nonadventitial tissue surrounding the ductus which would compress
the ductus if included within the stent-jacket, the edges of the
stent-jacket can be made incisive. If metal, the tips of the ribs
in a spine and ribs configured stent-jacket can be honed, for
example.
[1235] Atherosclerosis of the coronary arteries being the condition
most often demanding the reinstatement and sustainment of luminal
patency, these arteries are at the same time those ductus most
likely to benefit from and challenging to extraluminal stenting.
Even though the adventitia and perivascular fat are actively
involved in vascular physiology and pathology, a stent outside the
flow of contents, without radially outward protrusion into the
intima, and posing negligible perivascular compression should prove
overall advantageous. Provided the extraluminal stent is properly
configured, is compliant both circumferentially and longitudinally,
and is nonconstricting, the injured tissue regenerates and adapts
to its presence. Supported medically, generally to include a statin
drug, the disease-angioproliferated vasa vasorum should
regress.
[1236] Applied to a coronary artery, for example, use of the
minimal effective magnetic field strength, inclusion of
side-openings (perforations, fenestrae), and a base-tube of
suitable resilience in the correct internal diameter with cushion
lining as addressed below in the section entitled Necrosis- and
Atherogenesis-noninducing Conformation, results in the imposition
of little if any compressive force against the adventitial
microvasculature. Further to avoid compressing the vasa vasorum if
necessary, extraluminal segmental or chain-stents, addressed below
in the section entitled Sectional, or Chain-stents, Segmented and
Articulated, which subdivide a continuous stent into short sections
or substents, can be used. Regardless of the type or size ductus
treated, the continuous span (length) of adventitia enclosed can be
minimized by using a stent-jacket with perforations through the
base-tube and cushion lining and/or one divided longitudinally into
an articulated train of sub-stents, as addressed below in the same
section.
[1237] A foam lining allows slight protrusions of the jacket
adaxially that would otherwise irritate the substrate ductus and
accommodates deviation from cylindricality of the segment to be
encircled. For the present purpose, it allows some tissue
surrounding the ductus to be included within the stent- or
impasse-jacket whether perivascular fat surrounding an artery or
tissue surrounding a vein, as addressed below in the section
entitled Stent- and Shield-jacket Moisture barrier-coated
viscoelastic polyurethane foam Linings. An extraluminal stent of
larger internal diameter can be chosen to allow a uniform layer of
white perivascular (periadventitial) fat through which the vasa
vasorum courses to be included without hypoxic consequence or loss
in intrinsic vasodilatory (vasohypotonic) support; indeed, the fat
contributes additional cushioning.
[1238] Incised vasa vasora regenerate (see, for example, Santilli,
S. M., Wernsing, S. E., and Lee, E. S. 2000. "Transarterial Wall
Oxygen Gradients at a Prosthetic Vascular Graft to Artery
Anastomosis in the Rabbit," Journal of Vascular Surgery
31(6):1229-1239). With a stent-jacket that minimally interferes
with healing, unavoidable trauma to the perivascular
microvasculature should prove sustainable and heal in less than two
months. Much if not all of the vasa vasorum and vascular
innervation invested within periadventitial fat can be included
within the stent-jacket. Alternatively, based upon the
`perivascular adipose tissue dysfunction` concept (Guzik, T. J.,
Marvar, P. J., Czesnikiewicz-Guzik, M., and Korbut, R. 2007.
Perivascular Adipose Tissue as a Messenger of the Brain-vessel
Axis: Role in Vascular Inflammation and Dysfunction," Journal of
Physiology and Pharmacology 58(4):591-610), and provided that to do
so would not result in untenable injury upon the substrate artery
of the vasa vasorum, functionally altered and pathologically
destructive fat can be removed before the stent-jacket is applied
(see Chaldakov, G. N., Tonchev, A. B., Stankulov, I. S., Ghenev, P.
I. Fiore, M., Aloe, L., Rancic, G., Panayotov, P., and Kostov, D.
D. 2007. "Periadventitial Adipose Tissue (Tunica Adiposa): Enemy or
Friend Around?," Archives of Pathology and Laboratory Medicine
131(12):1766-1767; Pagano, P. J. and Gutterman, D. D. 2007. "The
Adventitia: The Outs and Ins of Vascular Disease," Cardiovascular
Research 75(4):636-639; Gao, Y. J., Lu, C., Su, L. Y., Sharma, A.
M., and Lee, R. M. 2007. "Modulation of Vascular Function by
Perivascular Adipose Tissue: The Role of Endothelium and Hydrogen
Peroxide," British Journal of Pharmacology 151(3):323-331; Stern,
N. and Marcus, Y. 2006. "Perivascular Fat: Innocent Bystander or
Active Player in Vascular Disease?," Journal of the Cardiometabolic
Syndrome 1(2): 115-120).
[1239] In the rabbit carotid artery, opening the sides of the
collar when the inlet and outlet remain flush to the adventitia
does not avert neointimal thickening (De Meyer, G. R. Y., Van Put,
D. J., Kockx, M. M., Van Schil, P., Bosmans, R., Bult, H.,
Buyssens, N., Vanmaele, R., and Herman, A. G. 1997. "Possible
Mechanisms of Collar-induced Intimal Thickening," Arteriosclerosis,
Thrombosis, and Vascular Biology 17(10):1924-1930). Neither
constriction nor constraint toward the margins apply to the
extraluminal stent described herein, which should not induce
neointimal thickening.
[1240] Residual muscle cell proliferation and neovascularization
left by the disease which did not spontaneously regress over time
is reduced with the aid of drugs. Once placed, an extraluminal
stent avoids the inner (adluminal) laminae of the lumen wall and
should become integrated into the tissue as to cause little if any
irritation. In an artery, avoidance of the lumen and minimization
of irritation afford the intima and media the opportunity to heal
from intrinsic as well as responding iatrogenic insults. Any ductus
that requires treatment is likely to present an adluminal condition
that makes preferable the placement of a stent peripheral or
abluminal thereto and away from the passage of contents.
[1241] 8f. Necrosis and Atherogenesis-Noninducing Conformation of
Stent-Jackets
[1242] The advantages in using stays to avoid the lumen or
miniballs to minimize its involvement once placed notwithstanding,
the fact that collaring the normal rabbit carotid artery with a
closed silicone elastomer (Dow Corning Silastic.RTM.) collar is
precisely a standard method for quickly inducing atherosclerosis in
the laboratory (see, for example, Hirosumi, J., Nomoto, A., Ohkubo,
Y., Sekiguchi, C., Mutoh, S., Yamaguchi, I., and Aoki, H. 1987.
"Inflammatory Responses in Cuff-induced Atherosclerosis in
Rabbits," Atherosclerosis 64(2-3):243-254; Booth, R. F. G., Martin,
J. F., Honey, A. C., Hassall, D. G., Beesley, J. E., and Moncada,
S. 1989. "Rapid Development of Atherosclerotic Lesions in the
Rabbit Carotid Artery Induced by Perivascular Manipulation,"
Atherosclerosis 76(2-3):257-268; Kockx, M. M., De Meyer, G. R. Y.,
Jacob, W. A., Bult, H., and Herman, A. G. 1992. "Triphasic Sequence
of Neointimal Formation in the Cuffed Carotid Artery of the
Rabbit," Arteriosclerosis and Thrombosis 12(12):1447-1457; Puranik,
R., Bao, S., Nobecourt, E., Nicholls, S. J., Dusting, G. J.,
Barter, P. J., Celermajer, D. S., and Rye, K. A. 2008. "Low Dose
Apolipoprotein A-I Rescues Carotid Arteries from Inflammation in
Vivo," Atherosclerosis 196(1):240-247), would appear to nullify any
potential benefit from a circumvascular stent (see also von der
Thusen, J. H., van Berkel, T. J. C., and Biessen, E. A. L. 2001.
"Induction of Rapid Atherogenesis by Perivascular Carotid Collar
Placement in Apolipoprotein E-deficient and Low-density Lipoprotein
Receptor-deficient Mice," Circulation 103(8):1164-1170; Reel, B.,
Ozkal, S., Islekel, H., Ozer, E., and 5 others 2005. "The Role of
Endothelin Receptor Antagonism in Collar-induced Intimal Thickening
and Vascular Reactivity Changes in Rabbits," Journal of Pharmacy
and Pharmacology 57(12):1599-1608).
[1243] However, even though medial smooth muscle cell
proliferation, negligible interruption to transmural flow (De
Meyer, G. R. Y., Van Put, D. J., Kockx, M. M., Van Schil, P.,
Bosmans, R., Bult, H., Buyssens, N., Vanmaele, R., and Herman, A.
G. 1997. "Possible Mechanisms of Collar-induced Intimal
Thickening," Arteriosclerosis, Thrombosis, and Vascular Biology
17(10):1924-1930), and the infiltration of leukocytes into the
media (Hagihara, H., Nomoto, A., Mutoh, S., Yamaguchi, I., and Ono,
T. 1991. "Role of Inflammatory Responses in Initiation of
Atherosclerosis: Effects of Anti-inflammatory Drugs on Cuff-induced
Leukocyte Accumulation and Intimal Thickening of Rabbit Carotid
Artery," Atherosclerosis 91(1-2):107-116) might not be completely
eliminated, a perivascular collar with open sides and wider ends
was found to minimize if not eliminate the adverse consequences
obtained when the collar was close-sided with ends that fit flush
to the artery (De Meyer et al. 1997).
[1244] Unlike atherogenesis inducing collars, the stent-jackets,
clasp-jackets, and impasse-jackets described herein are not flush
fit at the ends thus, and are lined with viscoelastic or
low-resilience polyurethane foam (moisture barrier-coated
viscoelastic polyurethane foam). The cushioned vasa vasorum should
adapt to negligible variation in pressure with the pulse, and the
fibrous adventitia proper should see little if any variation as
would excite a proliferative response at all (see, for example,
Haurani, M. J. and Pagano, P. J. 2007. "Adventitial Fibroblast
Reactive Oxygen Species as Autacrine and Paracrine Mediators of
Remodeling: Bellwether for Vascular Disease?," Cardiovascular
Research 75(4):679-689). With a suitably configured jacket, smooth
muscle cell proliferation and obstruction to transmural fluid
transport as leads to the retention of toxic metabolites and/or
cytokines (De Meyer et al. 1997) should not occur. The
susceptibility to medical management of adverse sequelae in the
rabbit model is addressed below in the section entitled Local
Release of Drugs by Miniballs and Stays.
[1245] That the vasa vasorum must not be stripped away (Wilens, S.
L., Malcolm, J. A., and Vasquez. J. M 1965. "Experimental
Infarction (Medial Necrosis) of the Dog's Aorta," American Journal
of Pathology 47(4):695-711) compressed (Ritman, L. and Lerman, A.
2007. "The Dynamic Vasa Vasorum," Cardiovascular Research
75(4):649-658) or obstructed (see, for example, Ravnskov, U. and
McCully, K. S. 2009. "Review and Hypothesis: Vulnerable Plaque
Formation from Obstruction of Vasa Vasorum by Homocysteinylated and
Oxidized Lipoprotein Aggregates Complexed with Microbial Remnants
and LDL Autoantibodies," Annals of Clinical and Laboratory Science
39(1):3-16; Martin, J. F., Booth, R. F., and Moncada, S. 1991.
"Arterial Wall Hypoxia Following Thrombosis of the Vasa Vasorum is
an Initial Lesion in Atherosclerosis," European Journal of Clinical
Investigation 21(3):355-359; Martin, J. F., Booth, R. F., and
Moncada, S. 1990. "Arterial Wall Hypoxia Following Hyperfusion
Through the Vasa Vasorum is an Initial Lesion in Atherosclerosis,"
European Journal of Clinical Investigation 20(6):588-592; with
additional references to follow) imposes severe constraints on the
design of a perivascular stent.
[1246] Probably anything that interferes with the release of nitric
oxide from the endothelium initiates atherosclerosis, and the
arterial walls of the coronary and carotid artery are subject to
inflammation and occlusion from both outside (vasa vasora) and
inside (from within the lumen). Compression from outside not only
deprives the substrate vessel of oxygen and nutrients but nitric
oxide. Endoluminally, the shear stress at bifurcations such as at
the branching of the common into the internal and external carotids
and the abdominal aorta into the iliac and then again into the
right and left internal and external iliac arteries likewise pose
compression inimical to the unimpeded delivery of saturated blood
to which the incidence of plaque at these sites attest.
[1247] For this reason, stent-jackets always incorporate a moisture
barrier moisture protected lining of viscoelastic polyurethane foam
to gently envelope rather than compress the fine vessels serving
substrate ductus. Sufficient retractive force must be exerted to
preserve luminal patency without compressing the vasa vasorum of
blood vessels or the small vessels that supply the walls of larger
vessels, the airway, esophagus, and gut, for example. Absent means
for preventing compression of its peripheral blood supply, no
segment of any ductus greater in extent than receives collateral
circulation should be compressed.
[1248] The avoidance of mechanical distortion by compression or
distention, perhaps the more so in a coronary artery with its
profuse and endarterially configured (citations below) vasa vasorum
(see Kwon, H. M., Sangiorgi, G., Ritman, E. L., Lerman, A.,
McKenna, C., Virmani, R., Edwards, W. D., Holmes, D. R., and
Schwartz, R. S. 1998. "Adventitial Vasa Vasorum in Balloon-injured
Coronary Arteries: Visualization and Quantitation by a Microscopic
Three-dimensional Computed Tomography Technique," Journal of the
American College of Cardiology 32(7):2072-2080), necessitates the
use of minimal magnetic field intensity combined with side openings
and a base-tube lined with a suitable cushioning material such as a
high density moisture barrier-coated viscoelastic polyurethane foam
(viscoelastic flexible polyurethane foam, slow recovery foam,
temper foam) of lower indentation force deflection (indentation
load deflection) and higher phase relaxation (phase change)
temperature in a thickness sufficient to minimize if not eliminate
perivascular compression.
[1249] The use of chain-stents also serve to minimize the extent of
adventitia closed off from its normal surrounding. While the
mechanism whereby the collar induces intimal thickening remains to
be fully elucidated, the substantial alleviation in adverse
consequences of placing a collar about an artery when the collar is
open-sided or perforated has been well established empirically (De
Meyer et al. 1997); George, S. J., Izzat, M. B., Gadsdon, P.,
Johnson, J. L., Yim, A. P., Wan, S., Newby, A. C., Angelini, G. D.,
and Jeremy, J. Y. 2001. "Macro-porosity is Necessary for the
Reduction of Neointimal and Medial Thickening by External Stenting
of Porcine Saphenous Vein Bypass Grafts," Atherosclerosis
155(2):329-336; Mehta, D., George, S. J., Jeremy, J. Y., Izzat, M.
B., Southgate, K. M., Bryan, A. J., Newby, A. C., and Angelini, G.
D. 1998. "External Stenting Reduces Long-term Medial and Neointimal
Thickening and Platelet Derived Growth Factor Expression in a Pig
Model of Arteriovenous Bypass Grafting," Nature Medicine
4(2):235-239).
[1250] With the extraluminal form of stenting described,
differential movement between the stent-jacket and the adventitia
is minimized, so that rather than to pulsate within a substantially
stationary collar, for example, the artery pulsates with little
resistance from the circumvascular stent, which acts as if it were
a part of the vessel wall, the pulse seeing no significant
resistance passing through the stented segment. Perforation and
segmentation of longer base-tubes, to include the foam lining, into
a train of joined substents, or a chain-stent, allows the
adventitia contact with the surrounding environment but reduces the
resilience of the base-tube, weakens it, and if not encapsulated
within a protective polymeric coating, exposes more of its surface
to chemical attack.
[1251] Breakdown of the base-tube not only interferes with stent
function but can initiate a pathogenic cascade that can lead to
necrosis. Exposure to the acidity and enzymes of the internal
environment places a demand upon the material of the base-tube for
retaining chemical integrity and pliancy. A thicker base-tube or
one made of a more resilient material or combination of materials
such as a suitable coextrusion is used. Newer materials suitable
for making base-tubes able to withstand the internal environment
for a long time are specified below in the section entitled
Internal Environment-resistant Base-tube Polymers,Metals, and
Combinations Thereof.
[1252] 8g. Means for Accommodating the Vasa and Nervi Vasora with
Special Reference to the End-Arterial Form and Neovascularization
of the Coronary Arteries
[1253] Even an extraluminal stent that is fully compliant with
pulsatile and tonic function and nonconstrictive is likely to be
more challenging to apply to a coronary artery than to any other
type ductus, to include other arteries, because:
[1254] a. The vasa vasora of the coronary arteries tend to be even
more profuse than are those of arteries generally (Hildebrandt, H.
A., Gossl, M., Mannheim, D., Versari, D., and seven other authors
2008. "Differential Distribution of Vasa Vasorum in Different
Vascular Beds in Humans," Atherosclerosis 2008 199(1):47-54;
Galili, O., Herrmann, J., Woodrum, J., Sattler, K. J., Lerman, L.
O., and Lerman, A. 2004. "Adventitial Vasa Vasorum Heterogeneity
Among Different Vascular Beds," Journal of Vascular Surgery
40(3):529-535; Galili, O., Sattler, K. J., Herrmann, J., Woodrum,
J., Olson, M., Lerman, L. O., and Lerman, A. 2005. "Experimental
Hypercholesterolemia Differentially Affects Adventitial Vasa
Vasorum and Vessel Structure of the Left Internal Thoracic and
Coronary Arteries," Journal of Thoracic and Cardiovascular Surgery
129(4):767-772), and,
[1255] b. The vessels of coronary artery vasa vasora are
end-arterial, or tree-, rather than network- or plexus-configured
(Gossl, M., Malyar, N. M., Rosol, M., Beighley, P. E., and Ritman,
E. L. 2003. "Impact of Coronary Vasa Vasorum Functional Structure
on Coronary Vessel Wall Perfusion Distribution," American Journal
of Physiology. Heart and Circulatory Physiology 285(5):H2019-H2026;
Gossl, M., Rosol, M., Malyar, N. M., Fitzpatrick, L. A., Beighley,
P. E., Zamir, M., and Ritman, E. L. 2003. "Functional Anatomy and
Hemodynamic Characteristics of Vasa Vasorum in the Walls of Porcine
Coronary Arteries," Anatomical Record. Part A, Discoveries in
Molecular, Cellular, and Evolutionary Biology 272(2):526-537; Kwon
et al. 1998. "Adventitial Vasa Vasorum in Balloon-injured Coronary
Arteries: Visualization and Quantitation by a Microscopic
Three-dimensional Computed Tomography Technique," Journal of the
American College of Cardiology 32(7):2072-2080; Jarvilehto, M. and
Tuohimaa, P. 2009. "Vasa Vasorum Hypoxia: Initiation of
Atherosclerosis," Medical Hypotheses 73(1):40-41; Ravnskov and
McCully 2009 op cit.), and
[1256] c. An artery suited for treatment with the means described
herein will almost always be atheromatous, the vasa vasorum having
already undergone neovascularization (Granada, J. F. and Feinstein,
S. B. 2008. "Imaging of the Vasa Vasorum," Nature Clinical
Practice. Cardiovascular Medicine Supplement 2:S18-S25; Kerwin, W.
S., Oikawa, M., Yuan, C., Jarvik, G. P., and Hatsukami, T. S. 2008.
"MR Imaging of Adventitial Vasa Vasorum in Carotid
Atherosclerosis," Magnetic Resonance in Medicine 59(3):507-514;
Goertz, D. E., Frijlink, M. E., Krams, R., de Jong, N., and van der
Steen, A. F. 2007. "Vasa Vasorum and Molecular Imaging of
Atherosclerotic Plaques Using Nonlinear Contrast Intraductal
Ultrasound," Netherlands Heart Journal 15(2):77-80), making the
vasa vasorum more difficult to mantle about.
[1257] An end-arterial blood supply connotes a lesser degree if not
a complete lack of overlap in the perfusion areas or territories of
adjacent root segments of the vasa vasorum tree, hence, a relative
lack of collateral circulation in the perfusion and drainage areas
of the substrate arterial wall. Apparently unique in this regard,
even if experiments on the aorta, carotid, or internal thoracic
arteries, for example, disclosed an ability to adapt to a properly
configured extraluminal stent, these results would not necessarily
apply to the coronary arteries. The moisture barrier-coated
viscoelastic polyurethane foam sufficiently accommodates the vasa
so that the vasa can adapt to the small force applied to it by the
stent. When unavoidable, a special coronary arterial chain-stent
consisting of millimetric-gauged substents strung along a flexible
tie line is contemplated.
[1258] However, this requires that the operator, working with the
aid of a high magnification varifocal binocular endoscope
(boroscope), sequentially position each substent, sliding it along
the tie line to a position to least encroach upon the vasa before
setting that substent in position around the substrate artery. To
avoid the profuse vasa would, however, be a tedious and almost
certainly imperfect exercise that would significantly increase
procedural time. For this reason, the placement of a longitudinally
continuous stent-jacket with lining and side openings or
perforations as adequately accommodates and does not completely
obstruct the vasa vasorum so that it can adaptively recover is
preferred.
[1259] 8h. Requirement for Moisture Barrier-Coated Viscoelastic
Polyurethane Foam Linings
[1260] The implants described herein have a lining of
nonbiodegradable or bioresistant viscoelastic polyurethane moisture
barrier-coated viscoelastic polyurethane foam. Such a lining not
only cushions the substrate (treated) ductus, allowing some
latitude in the design of the implant, which can therefore include
slight adaxial protrusions if necessary, but protects the tissue at
the outer surface of the ductus and spontaneously adapts to out of
round and noncylindrical ductus without necessitating the custom
making of devices to accommodate these. The microvasculature of the
adventitia such as the vasa vasora and and small nerves of larger
vessels to include the nervi vasora and plexuses of larger vessels,
such as those of the common, internal, and external carotid
arteries, must be protected from compression or tamponade as would
obstruct the supply of oxygen and nutrients to the cells of the
luminal wall and remove wastes.
[1261] As indicated by the results of experiments cited above in
the section entitled Necrosis and Atherogenesis-noninducing
Conformation of Stent-jackets, an unfenestrated silicone
elastomeric cuff placed about the common carotid artery of a rabbit
plays a role in initiating the atherogenetic process. Obstruction
to the fine subsidiary vessels supplying a larger artery, whether
the consequence of protracted elevated serum cholesterol in the
vasa vasora, encroachment upon the microvasculature that supplies
the esophagus or trachea by an adjacent tumor, possibly
constriction by a vascular ring, or a noncompliant stent-jacket is
likely to aggravate the disease. Likewise, sustained compression of
the fine nerves of the outer tunic will impair medial smooth muscle
function within the wall.
[1262] Stent and impasse-jackets are fenestrated and provided with
a special lining. Existing viscoleastic polyurethane foams, or
`memory` foams, have a useful life proportional to the material
density of many years and newer such material can be made with
closed cells that minimize infiltration with blood, serous fluid,
or tissue, gas exchange with the internal environment or
`breathing` accomplished with the fenestrae, eliminating the need
for open cell material. The foam lining provides numerous benefits
related to eliminating the need for complete complementarity of
conformation at the interface between the internal surface of the
jacket and external surface of the ductus. The lining prevents
compression of the fine vessels and nerves by holding the internal
surface of the base-tube or radially outward lining at a distance.
To maximize perforations through the stent-jacket thereby exposing
the adventitia to its normal milieu as much as possible, the
moisture barrier-coated viscoelastic polyurethane foam lining is as
discontinuous as its function in the specific stent-jacket will
allow.
[1263] A similar lining is used in an impasse-jacket wherein it is
confined to the margins. The atrophy, hypoxia, and toxicity of
obstructing the microvasculature is especially true of the coronary
arteries, which have vasa vasora that end-arterial, afford
relatively little collateral circulation and in atherosclerosis
will have grown dense. The foam lining accommodates reductions in
gauge following a subsidence in swelling too slight to require the
use of an expansion insert, minor changes in gauge due to flaring,
and allows impasse-jacket designs that call for some slight inward
protrusions of the jacket. Another purpose of the moisture
barrier-coated viscoelastic polyurethane foam lining with an
expansion insert and/or somewhat larger base-tube is to allow for
growth in a younger patient by using a thicker growth compensating
layer of the foam to take up the space between the adventitia and
the internal surface of the stent-jacket oversized pending
acquisition of the adult gauge.
[1264] The same latitude will accommodate hyperplasia or swelling
at a later time regardless of the cause. Except for a rare
pediatric patient with a progeroid syndrome, the pathology will be
other than atherosclerotic. The ductus must afford sufficient
circumvascular clearance for an adult sized stent-jacket to be
placed. The same accommodation would apply were the ductus subject
to later inflammation. Yet another value in a foam lining is that
it allows the application to the internal surface of an
intrinsically magnetized stent or impasse-jacket of non-round
material to increase the the tractive force exerted. Moisture
barrier-coated viscoelastic polyurethane foam linings are addressed
above in the section entitled Preliminary Description of the
Invention and below in the section entitled Stent- and
Shield-jacket Moisture barrier-coated viscoelastic polyurethane
foam Lnings.
[1265] 8i. Positional Stabilization of Implants
[1266] Reduction in the risk of stent failure by adventitial or
medial delamination or the loss of retention of miniballs or stays
as the ductus-intramural intravascular component of an extraluminal
stent under the constant if minimized outward pulling force of the
stent-jacket, can be enhanced by giving these a surface texture
that encourages tissue infiltration. Miniballs can be coated with a
solder made to flow when placed in an alternating magnetic field,
and stays can be treated thus and/or coated with cement on ejection
from the stay insertion tool. The bonding agent is not intended to
survive the internal environment, but rather to allow the
surrounding tissue to infiltrate and replace it, thereby
perpetuating cohesion. Dense connective tissue, such as tendons,
which strengthen under stress, consist of parallel type I collagen
fibers bound together by other proteins.
[1267] The adventitial or fibrosal tunic, which consists largely of
type I collagen fibers at different angles and elastin fibers in
proportion to the elasticity of the ductus, should likewise respond
to the transverse magnetic field force on the implants by
strengthening and aligning to better resist the centrifugal
(sideways, axifugal) force imposed. Means for testing the strength
of the ductus wall and a tendency to delaminate are provided below
in the section entitled Testing and Tests. A nonoriented
arrangement of fibers may necessitate an interim augmentation in
retentive strength that affords sufficient elasticity for the
intrinsic fibers to adapt. Bonding agents eliminate elasticity in
their immediate vicinity but not in adjacent tissue. Stays offer
the advantage of insertability with a coating of surgical cement at
room temperature that if necessary, can be reduced in curing time
by warming.
[1268] An accessory syringe holder can be attached to the stay
insertion tool to deliver cements that consist of more than one
component. Miniballs jacketed within a layer of a quick setting
surgical cement formulated to melt when warmed, or a protein solder
to denature (flow), at a temperature low enough to avoid weakening
the intrinsic fibers following insertion are options. Another is to
use electrically or fluidically heated injection syringe
tool-inserts, as addressed below in the section Radial Projection
Units, to deliver fluid cement or a molten solder before or after
implantation. The bonding agent is kept warm by a coil in the
syringe before use, targeted injection and the thermal insulation
value of the polymeric body of the tool-insert serving to minimize
the heat distributed to the surrounding tissue.
[1269] Except in a blood vessel where ischemia is a constant
threat, an interval for initial setting can be gained by leaving
the barrel-assembly in position following injection during which
the stent-jacket is applied. The barrel-assembly is thus
prepositioned so that a slight transluminal retrraction places the
discharge exit port or ports at the site for implantation. The need
for short initial setting and curing times encourages the use of
cyanoacrylate cements over alternative bonding agents, although
some others set quickly when heated. The conduction of potentially
thrombogenic temperatures is abated by means of a cooling catheter
or by passing chilled fluid past a syringe type heated injector
when a fluid system is used. Made of heat-resistant polysiloxanes
or silicone polymer, for example, the body of the injector is
inherently insulated.
[1270] When the implants are miniballs, such immediate coordination
between heated tool-insert injection syringes and the discharge of
miniballs is an example of the single entry and withdrawal
advantage provided by a barrel-assembly having the radial
projection units needed built into it or ensheathable in a
size-matched slip-over combination-form radial projection catheter
to constitute a bipartite or duplex barrel-assembly, as addressed
below in the section entitled Distinction in Ablation or Ablation
and Angioplasty-capable Barrel-assemblies as Unitary or Bipartite.
In the same way, a barrel-assembly equipped with one or more
injection tool-inserts can introduce a quick acting tumefacient to
allow a lumen wall that has become too thin due to remodelling to
be implanted without the need to withdraw and reenter. Similarly,
when discharge implantation is uninvolved, a radial projection
catheter (radial projection assembly), allows the application of
whatever therapeutic means are appropriate, eliminating the need to
withdraw one assembly and reenter with another, much less having to
repeatedly alternate between two or more.
[1271] 8i(1). Use of Solid Protein Solders
[1272] Several means for overcoming delamination or laminar
avulsion under the tractive force placed on the ductus-intramural
implants are provided. This risk inheres in perimedial or medial
placement with the ductus-intramural implants under constant if
minimal outward tractive force where it does not pertain to an
endoluminal stent. However, an endoluminal stent poses more
numerous and serious problems, to include endothelial dysfunction
and clogging. Susceptibility to delamination is evaluated by a
pretest described below in the section entitled Testing and Tests,
and prevented through use of one or a combination of special
measures to be described. The stays or miniballs can, for example,
be coated with a eutectic solid protein solder that is heated to
flow (melt when denatured) with means for applying heat that are
incorporated into the apparatus or by placement in an alternating
magnetic field, for example. Solders are addressed below in
numerous sections, to include Medication-coated Miniballs, Stays,
and Prongs with a Heat-activated (-melted, -denatured) Tissue
Adhesive-hardener or Binder-fixative and Stays Coated with a Solid
Protein Solder Coating and Cyanoacrylate Cement.
[1273] Since the avoidance of higher temperatures is desirable in
all solder tissue bonding (see, for example, McNally, K. M., Sorg,
B. S., Welch, A. J., Dawes, J. M., and Owen, E. R. 1999.
"Photothermal Effects of Laser Tissue Soldering," Physics in
Medicine and Biology 44(4):983-1002; erratum 44(6):1579; Soller, E.
C., Hoffman, G. T., McNally-Heintzelman, K. M. 2002. "Use of an
Infrared Temperature Monitoring System to Determine Optimal
Temperature for Laser-solder Tissue Repair," Biomedical Sciences
Instrumentation 38:339-344), the continued development of solders
with lower melting points is critical to their use and may be
considered a certainty. For ductus outside the vascular tree, newer
eutectic solders that flow at lower, less injurious temperatures
are under development (Lauto, A., Hook, J., Doran, M., Camacho, F.,
Poole-Warren, L. A., Avolio, A., and Foster L. J. 2005. "Chitosan
Adhesive for Laser Tissue Repair: In Vitro Characterization,"
Lasers in Surgery and Medicine 36(3):193-201). Advancement is also
being made with respect to increasing bond strength (Lauto, A.,
Foster, L. J., Ferris, L., Avolio, A., Zwaneveld, N., and
Poole-Warren, L. A. 2004. "Albumin-genipin Solder for Laser Tissue
Repair," Lasers in Surgery and Medicine 35(2): 140-145).
[1274] Differentially melting the solder layer about a miniball or
stay in vivo without causing heat injury to the surrounding tissue
is made possible, for example, by including different additives or
inclusions in the solder. Targeted heating can be achieved using
focused ultrasound (see, for example, O'Neill, B. E. and Li, K. C.
2008. "Augmentation of Targeted Delivery with Pulsed High Intensity
Focused Ultrasound," International Journal of Hyperthermia
24(6):506-520). Another approach uses the differential absorption
of laser generated near-infrared radiation by multiwalled carbon
nanotubes (see Ghosh, S., Dutta, S., Gomes, E., Carroll, D.,
D'Agostino, R. Jr., Olson, J., Guthold, M., and Gmeiner, W. H.
2009. "Increased Heating Efficiency and Selective Thermal Ablation
of Malignant Tissue with DNA-encased Multiwalled Carbon Nanotubes,"
ACS [American Chemical Society] Nano 3(9):2667-2673).
[1275] Other processes which involve the use of magnetism may
dictate placement of the stent-jacket only after placement of the
implants, precluding use of a stent-jacket or a specially adapted
stent-jacket as a heat shield or as addressed in the section below
entitled Double-wedge Stent and Shield-jacket Rebound-directing
Linings as a means for preventing perforations during airgun
implantation (see, for example, Steinke, F., Andra, W., Heidec, R.,
Wernera, C., and Bellemann, M. E. 2007. "Rotating Magnetic
Macrospheres as Heating Mechanism for Remote Controlled Drug
Release," Journal of Magnetism and Magnetic Materials
311(1):216-218). Solder coated miniballs can be heated from
without, which heats intervening tissue, or magnetically excited by
an external source to radiate heat from within.
[1276] Using the latter, a solder with a low melting point makes it
possible to denature (melt) the solder coating while minimizing the
diffusion of heat to the surrounding tissue. Where unavoidable,
potentially injurious heat is quickly lowered to body temperature
by passing chilled gas down a barrel-tube. In a blood vessel, this
is done with a temperature-changing, or `cooling` catheter such as
a rod kept in a refrigerator or freezer which does not use or emit
gas. Cooling catheters pertain equally to barrel-assemblies and
stay insertion tools, which include side mounted spring clips for
attaching auxiliary lines or cables for fiberoptic endoscopes,
lasers, or cooling catheters, for example. Cooling catheters are
addressed below in the section entitled Cooling Catheters
(Temperature-changing Service-catheters).
[1277] Soldering is performed at between 50 and 100 degrees
centigrade (Hoffman, G. T., Byrd, B. D., Soller, E. C.,
Heintzelman, D. L., and McNally-Heintzelman, K. M. 2003. "Effect of
Varying Chromophores Used in Light-activated Protein Solders on
Tensile Strength and Thermal Damage Profile of Repairs," Biomedical
Sciences Instrumentation 39:12-17), and thus spans a temperature of
90 degrees centigrade at which thrombogenesis appears to be minimal
(Post, M. J., de Graaf-Bos, A. N., Posthuma, G., de Groot, P. G.,
Sixma, J. J., and Borst, C. 1996. "Interventional Thermal Injury of
the Arterial Wall: Unfolding of von Willebrand Factor and its
Increased Binding to Collagen after 55 Degrees C Heating,"
Thrombosis and Haemostasis 75(3):515-519). The temperature stated
herein is based upon the references cited and not to be interpreted
in a limiting sense.
[1278] 8i(2). Means for Inducing the Formation of a Strong
Implant-Tissue Bond
[1279] Specific substances for inducing the formation of a strong
implant-tissue bond are addressed in several sections below, to
include those entitled Specification of Cyanoacrylate Tissue
Sealants and Bonding Agents and Medication-coated Miniballs, Stays,
and Prongs with a Heat-activated (-melted, -denatured) Tissue
Adhesive-hardener or Binder-fixative. A strong ductus-intramural
implant-tissue bond discourages migration, delamination, and
pull-through. Such an agent must strengthen the surrounding tissue
and not just provide a strongly adherent bond at the implant-tissue
interface. The implants generally are given a textured surface that
includes undercuts to improve initial adhesion, then tissue
infiltration, and when applicable, the uptake of medication
incorporated into or applied beneath the outer bonding agent.
[1280] While wiped away from the outermost prominences of the stay
as it enters, the deep surface texture of the stays retains and
carries the coating to the implantation site. The inclusion or
collateral implantation of a drug or drugs to toughen the
surrounding tissue and thus impart resistance to pull-through by
inducing cell proliferation, the formation and transport of
fibroblasts, or the thickening of connective tissue fibers, for
example, cannot be depended upon. This is because a. For the drug
or drugs to exert the desired effect takes too long, b. To implant
the drug or drugs through an intrusive procedure as a pretreatment
at an earlier date unduly imposes upon the patient, d. May detain
therapy needed promptly, and d. The toughening obtained might
subside as the drug is dissipated. The use of tissue hardening and
bonding agents with an immediate fixative and stabilizing effect is
thus preferable.
[1281] If not intended to increase initial retentive strength but
rather to impart additional strength over time, various substances
are available (see, for example, Hunter, W. L., Gravett, D. M.,
Toleikis, P. M., Maita, A., Signore, P. E., Liggins, R. T., and
Guan, D. 2007. "Medical Implants and Fibrosis-inducing Agents,"
U.S. Pat. No. 7,166,570). `Fibrosing` as incorrectly denoting
scarring would, however, be weakening. By contrast, tissue
hardening and bonding agents as discussed below can be formulated
to provide an immediate increase in strength and encourage
infiltration and gradual replacement by the surrounding tissue. A
service-catheter used in a barrel-assembly can similarly be
multiluminal, and fed from separate syringes, reservoirs, or
containers can be open or hypotube-ended. With miniballs, more than
one service-channel may be disallowed as restricting the size of
the miniballs that can be used; however, a multiluminal catheter
will always provide an adequate flow rate for any fluid substance
passed therethrough with sufficient force.
[1282] Whether encapsulated within solder, stays are readily coated
with any other fluid agent or combination thereof by separately
controlled auxiliary syringe holding frames, as addressed below in
the section entitled Stay Insertion Tool Auxiliary Syringes. An
insertion tool with two holding frames attached is especially
versatile for combining various liquid or semiliquid substances as
adjunctive to implantation. For example, a tunica media swelling
agent can be delivered from an auxiliary syringe attached at one
side of the tool, and a tissue hardener from an auxiliary syringe
attached at the other side. Using a stay insertion tool, the
delivery of a gas, aerosol, gas with a fine powder dispersed in it,
or a slurry is accomplished by attaching a delivery line (catheter)
to the tool with spring clips provided on the tool, as described
below in the section entitled Stay Insertion Tool Mounting Spring
Clips.
[1283] Compatible liquid or semiliquid substances from separate
syringes can be delivered together through the one line leading
from either holding frame to the tool. The same limitation in size
pertains to auxiliary syringe holding frame delivery tubes or
service catheters affixed to one or both sides of a stay insertion
tool by means of spring clips, which must have outlet ends small
enough to position over the stay ejection slot. When the contents
of the holding frame to either side must be deposited on the stays
as each is ejected, then both holding frames must feed open tubes
or injection needle-ended hypotubes suspended over the stay or the
same single or multilumen line as it is emitted. Unless each
holding frame feeds one of the two lumens in a distal segment of
the line made of dual lumen tubing or the tube ends are small
enough to be juxtaposed, the exit tip of one must be nudged aside
to allow the overlying position for the other.
[1284] As with discretionary injection, this requires a larger
access incision. However, even though the diameter is limited,
whether a service catheter in a barrel-tube or attached alongside a
stay insertion tool, each lumen in a multiple lumen tube can be
supplied from a separate syringe, canister, or other source. The
distal or working ends of the syringe delivery or service catheters
wet the stays as these are ejected or can end as hypotube injection
needles ridgidly angled for injection with each stay as it is
inserted. The distal segment of the hypotube can also be left
flexible for discretionary use. Discretionary will require a larger
entry wound to accommodate a hemostat or other forcep, pliars, or
tweezer-configured tool for maneuvering the injection needle.
[1285] Unlike a stay coating line, a hypotube injection lines and
open ended service catheters used to eject or spray fluid into the
entry portal are not limited by the space available over the stay
ejection slot hence, in diameter and rate of outflow.
Interchangeable ending segments, open and hypotube soft and
angle-ended, are more versatile and no more demanding on entry
portal size than would be a separate line likewise adapted to
accept ejection and injection distal segments. Connection of a
narrower open ended tube to a hypotube line is by means of a size
adapter. Injection tool-inserts in barrel-assemblies and radial
projection catheters can likewise be used to deliver any fluid
substance or substances in any combination. Miniballs must likewise
have a deeply textured surface for wetting just prior to insertion
to be carried to the implant site; otherwise, miniballs incorporate
constituents as solids. Versatility in wet coating upon insertion
is, however, a relatively minor consideration in choosing stays
over miniballs.
9. Minimizing the Risk of Rebound
[1286] To minimize the risk of rebounding from, penetration, or
puncture of the fibrous outer layer or sheath of the vessel or duct
while taking advantage of the elasticity of the lumen wall,
miniball discharge is at a 45 degree or less, i.e., acute, angle.
Compared to a trajectory perpendicular to the lumen surface,
penetration at an acute angle aids implantation by undercutting the
media with less risk of perforating the tunica adventitia, which
includes collagen fibers at angles and is tougher than the
subjacent tissue. The longer trajectory extends the resultant
trauma and inflammation; however, the reobstruction if not abrupt
closure that appears to vary with the extent of vessel wall damage
by balloon over-inflation and dissection is quite different in form
and much more extensive than is the suddenly introduced and highly
circumscribed penetration of the intima and media by the miniature
balls.
[1287] An adventitia weakened by disease can sometimes be
strengthened chemically and/or bolstered through the application of
an elastic clasp-jacket of which the lining is coated with a tissue
hardener-adhesive. A double-wedge lined stent-jacket, as addressed
below in the section entitled Double-Wedge Stent- and Shield-jacket
Rebound-Directing Linings, placed before initiating discharge both
prevents perforations and redirects the miniball away from the
lumen and into the lumen wall. Few bonding or hardening agents will
hold up to the internal environment wherein enzymes, oxidation, and
constant tissue replacement will eventually eliminate most; the use
of these substances applies when the healing process is expected to
re-establish the strength that had been lost to disease. Success is
optimized by efficient technique that minimizes operating time. As
in conventional endovascular interventions, general anesthesia is
usually unnecessary.
[1288] In patients for whom an antecedent angioplasty has recovered
adequate luminal diameter and throughflow, the apparatus is devised
to implant the miniballs in the least amount of time. Positioning
the muzzle-head and exit-ports to place the miniball implants in a
tight uniform pattern too difficult and time-consuming for manual
control, function thus is relegated to a semiautomatic positional
control and discharge system. Whether control is manual or
automatic, superior steerability, rotatability, ability to place
multiple implant miniballs per discharge and contrast enhancement
for clear viewability of the angular and transluminal position of
the muzzle-head and implants allow efficient positioning that
likewise reduce procedure times.
[1289] Hence the incorporation into the muzzle-head of a flexible
joint and turret-motor, for example. One means for urging the
muzzle-head toward a certain arc of the wall if necessary is
addressed above in the sections entitled Comparison of Extraluminal
with Endoluminal, or Conventional, Stenting and Steering and
Emergency Recovery of Implants with the Aid of an External
(Extracorporeal) Electromagnet. This measure reduces the likelihood
of completely cutting off the circulation during the ballistic
implantation of an artery. As addressed below in the section
entitled Double-wedge Stent- and Shield-jacket Rebound-directing
Linings, when the risk of rebound is pronounced or intolerable, a
special stent-jacket lining is employed. Such a lining can be
wetted with a coagulant, other therapeutic substance or substances,
and/or medication.
[1290] Wherever a risk of rebound into the circulation of an
implant or tissue sealant exists, a means for countering this risk
is provided, to include the incorporation of innocuous ferrous
matter to allow magnetic removal. Should a miniball enter the
circulation, it is immediately trapped and held in an
impasse-jacket prepositioned upstream or with the aid of an
external electromagnet, such use addressed in sections of
appropriate title. Impasse-jackets incorporate an extraction grid
to allow pulsing a powerful extracorporeal electromagnet to move
the trapped miniball to a distance outside the ductus or entirely
outside of the body, which rarely if ever necessary, can be
accomplished safely.
10. Concept of Ballistic Insertion
[1291] Ballistic implantation and its opposite, sudden extraction
using a powerful extracorporeal electromagnet are intended to
overcome the puncture and penetration resistance of the target
tissue so suddenly and forcefully that an elastic reaction of
displacement and resistance to stretching around the entry hole and
the penetration trajectory is eliminated and injury to the
circumjacent cells minimized. The lumen wall is struck too suddenly
to displace or deform; that is, the rate of deformation or strain
rate is exceeded, precluding compression of the tissue rather than
its sudden puncture and penetration, even without affecting the
temperature of the tissue. Moreover, the diameter of the wound
trajectory is that of the miniball implant alone without increase
due to the need for an insertion instrument.
[1292] Stent implantation by such means should affect only the
tissue in and immediately surrounding the trajectory, the latter
closing in and releasing exudate to contain the miniball implant
and commence the healing process. In addition to extracorporeal
means of imaging, the devices used to accomplish ballistic
insertion, barrel-assemblies,incorporate aids to the obtaining of a
clear view such as an angioscope or intravascular ultrasound probe
within the state of miniaturization. FIG. 66 shows an
edge-discharge muzzle-head configured to allow the axial insertion
of a cabled device to include those used to assist viewing. An
adapted semiautomatic repeat action gas-operated airgun with single
or multiple barrel-tube barrel-assembly can be made to affect
miniball implantation with relatively tight control over the exit
velocity and impact force.
[1293] Above a certain exit velocity, the miniball will perforate
entirely through the wall of the ductus. For the purpose of
extraction, this level of momentum is always applied, but in pulses
brief enough to allow control over the distance the miniball is
drawn with each pulse, the absolute distance changing according to
the type and condition of the tissue traversed. For infixion,
however, there will be a range of lower exit velocities and
momentum such that the adaxial layers or tunics in the ductus wall
will dissipate some of the momentum to more impede the miniball the
further it penetrates with the fibrous outer layer bringing the
miniball to a stop.
[1294] In an artery, for example, the layers of the vessel wall
include the smooth muscle of the tunica media, the internal elastic
lamina inside (surrounded by, medial or adaxial to) the tunica
media, and the external elastic lamina outside (surrounding,
external or abaxial to) the tunica media, each posing resistance to
penetration (Holzapfel, G. A. and R. W. Ogden 2010. "Constitutive
Modelling of Arteries," Proceedings of the. Royal Society, Series
A. Mathematical, Physical & Engineering Sciences 466(2118):
1551-1597). The tunica adventitia or outer fibrous layer of the
vessel then poses an additional layer of resistance to penetration
which prevents the miniball from perforating. Anoher moderating
factor is discharge at an acute forward or distal abaxial angle,
which increases the distance through the wall and reduces the
perpendicular vector.
[1295] Continued travel down the interface between the media and
the adventitia will have been predetermined and compensated for.
The cells in the trajectory are crushed, with the cytoplasm and
membranes troweled against the sides or wall of the trajectory. The
release of fluid contents and inflammatory swelling quickly
backfill the trajectory and seal the miniball at the terminus.
Provided a type tissue is disease-free, the range of variation in
mechanical properties from one conspecific or congeneric individual
to the next will be small; the tissue having to satisfy the same
physiological requirements in both individuals (Humphrey, J. D.
2003. "Review Paper: Continuum Biomechanics of Soft Biological
Tissues," Proceedings of the. Royal Society, Series A.
Mathematical, Physical & Engineering Sciences 459(2029)3-46;
Fung, Y.-C. 1993. Biomechanics: Mechanical Properties of Living
Tissues, New York, N.Y.: Springer-Verlag).
[1296] Allowing for age, behavior, and genetics, this is even true
across vertebrate classes. Bulk and shear modulus, elasticity,
resistance to puncture and penetration, and so on, establish a
range of exit velocities for properly seating the miniballs in
normal tissue. However, disease-free tissue almost never warrants
implantation, while diseased tissue is associated with a breakdown
in physiological function, hence, deviation from the normal range
of values for tissue strength, making in situ testing at the
prospective implantation site imperative. Based upon in situ tissue
testing as addressed below in the section entitled Testing and
Tests, the discharge velocity is set to penetrate to and be stopped
by the adventitia. Only diseased tissue requires medication or the
application of retractive force for restoration to a functional
conformation. Unlike healthy tissue, diseased tissue varies over a
wide range of hardness and strength from malacotic to sclerotic or
indurated.
[1297] For example, treatment of an artery with ductus-intramural
implants, especially those to be subjected to the tractive force of
a magnetic field, warrants cautious application to patients
susceptible to spontaneous rupture of the elastic laminae and those
in whom an antecedent conventional angioplasty resulted in balloon
overstretching. The in situ tests provided will uncover such a
condition. The progressive mineralization of vascular plaque by
calcification can make it as hard as concrete, necessitating a
preliminary atherectomy, usually with a rotatory grinding burr type
cutting tool. That in direct stenting, stays, which are inserted
from outside the adventitia can avoid such preparatory treatment of
the internal surface of the ductus, which carries the risk of
perforation, is mentioned above in the section entitled
Circumstances Dissuading or Recommending the Use of Stays. Wide
variation in tissue hardness is no less pertinent to implantation
of medication miniballs as miniballs that represent or additionally
represent the intraductal component of a magnetic stent.
[1298] To test diseased tissue of the same kind and degree of
advancement in different subjects immediately upon death as to
minimize the effects of autolysis indicates the range in exit
velocity to implant and not perforate for that condition, and such
results for different conditions over the malacotic-sclerotic range
establish the overall gross range for the initial control settings
required by the apparatus. Within this overall range, different
pathology and individual variation will dictate the resolution or
fine adjustment required. Even tissue immediately adjacent to a
lesion will not exhibit the same mechanical properties as will the
lesion itself. Even though miniballs are bioinert, and with the
exception of the largest for use in the gastrointestinal tract,
airway, and organs, tiny, so that a perforation would not result in
serious injury, testing is not accomplished through test
discharges.
[1299] The reason is that while a single test discharge could do
little injury, but multiple test discharges could do serious
injury. Accordingly, methods and apparatus for establishing the
penetration, perforation, and patenting forces best to apply along
different areas about the circumference of the diseased ductus
tissue to be implanted are obtained. Distinctions among arcs are
ascertained because these can be translated into a discretionary
distribution of forces to be applied to each area, the means
employed not limited to a uniform application of forces all around.
If to be stented, the intrinsic magnetization of the thin stainless
stent-jacket or of the small bar magnets mounted about the outer
surface of the polymeric stent-jacket can be varied in magnetic
force or some can be omitted. The base-tube can be varied in
thickness, in material or materials, hence, resilience, can be
perforated, or a side-slot used to clear an attachment.
[1300] Any type ductus may present an eccentric condition best
treated were medication and/or radiation closely targeted at a
certain arc. Any barrel-assembly can accomplish eccentric
discharge. With a simple pipe type, rotation is manual. In radial
discharge barrel-assemblies, one or more exit-ports about the
circumference of the muzzle-head can be rotated clockwise or
counterclockwise with the turret-motor, and the rotary magazine
clips can be instantly changed to change which barrel-tubes
discharge a miniball. To clear an attachment of connective tissue,
for example, the holes in the rotary clip feeding the barrel-tube
or tubes directed at the area are left blank or plugged. If
stenting is involved, then a stent-jacket with a cut out or a wider
side-slit, or side-slot, is used to straddle the omitted or blanked
out arc. Concerns pertinent to miniballs include perforations,
pulling through the superjacent tissue under the constant if weak
tractive force of the stent-jacket resulting in stent failure,
mispositionings, entry into the lumen, and if the lumen of a blood
vessel, then embolization.
[1301] Wide stays coated with cyanoacrylate cement, which are not
likely to pull through, are more appropriate for weaker tissue; but
were this to occur, retrieval would require minor surgery. All are
responded to with multiple preventive and corrective measures, and
none pertain to any meaningful extent to stays. Implanted
ballistically, the use of miniballs arouses concern that either
because of proximity to neighboring structures, a perforation with
continued travel of the miniball would pose an inordinate risk, or
that the arterial wall may have already become (see, for example,
Richardson, P. D. 2003. "Elliptic Delamination as an Early Stage in
Atherosclerotic Plaque Evolution: Fluid Mechanical Aspects,"
Biorheology 40(1-3):417-421) or will become so weakened as to
become susceptible to rupture, stretching, or aneurysmal failure.
Weakening of the lumen wall is more likely to arise when a
positional control system has been used to place the miniballs in a
close formation.
[1302] Means for preventing adverse consequences are incorporated
in the inventive system in the form of emergency recovery means,
such as the recovery electromagnets in the muzzle-head or stay
insertion tool, the prepositioning of stent-jackets and downstream
impasse-jackets, and a method for adapting a magnetic resonance
machine for emergency interception and resituation or extraction of
a problem miniball specified in section X2c below entitled
Stereotactic Arrest and Extraction of a Circulating, Dangerously
Mispositioned, or Embolizing Miniball. Emergency extraction
consists of pulling the miniball from its instant position whether
moving or having been stopped by a jacket or embolic filter with a
powerful external electromagnet stereotactically positioned to
extract the miniball through the least injurious trajectory into
neighboring tissue where it will be harmless, to a more accessible
location for recovery, or entirely outside the body.
[1303] When trapped by the recovery electromagnets in the
muzzle-head, no further action is required. Pull-through relates to
miniballs and delamination to ductus-intramural implants of any
kind. Vulnerable structures along the trajectory will be apparent,
the absolute size of the projectile limits the injury that can
result, and perforations tend to seal quickly. A primary reason for
ballistic implantation is precisely the fact that the access path
is no larger than that of the implant itself, is therefore
minimally injurious, quickly seals, and quickly heals. While
perforation by the largest miniballs might injure a ganglion,
nerve, lymph node, or blood vessel, regeneration and redundancy
would make permanent damage even from these, much less smaller
miniballs, virtually impossible. Smaller miniballs shot entirely
through the adult body should produce little damage.
[1304] For a miniball to gain entry into the lumen of a blood
vessel other than that treated is improbable, for the level of
embolization by the minute miniball to be associated with an
exclusive territory so that tissue supplied is dependent upon it as
lacking collateral circulation is improbable, and for the miniball
not to be instantly extractable through the use of an external
magnet before any significant injury resulted is impossible. More
specifically, a perforation will tear through capillaries, venules,
muscle and nerve fibers along the trajectory, but due to the
absolute diameter of the trajectory, produce negligible trauma.
Interposed vessels and organs that were perforated would quickly
seal themselves and heal, and the severing of nerve fibers that
produced some functional impairment internally or that resulted in
an area of cutaneous numbness would soon regenerate. Even without
the multiple precautionary elements built into the apparatus, a
loose miniball that entered the bloodstream, could be stopped with
an extracorporeal hand-held electromagnet.
[1305] When the muzzle-head is not too large in diameter to
approach the miniball where the external extracorporeal
electromagnet intercepted it, raising the current to the inmate
tractive electromagnets in the muzzle-head while deenergizing the
external magnet will force the miniball into the antemagnet
chamber. Viewed throughout with suitable contrast and imaging
equipment, were the exit velocity set too low so that miniballs
failed to penetrate the lumen wall, for these to intravasate or
enter the bloodstream unseen and not otherwise noticed is
improbable, and for a miniball to move past the partially energized
recovery electromagnets much less an embolic filter (trap-filter)
at the front of the muzzle-head is more improbable. For a miniball
to move past an impasse-jacket that had been designed and
prepositioned precisely to stop and hold it is virtually
impossible, and for retrieval to take more than a few seconds is
most improbable.
[1306] To maximize miniball selectivity, the probe of the
stereotactic extraction armature is drawn down to a fine needle.
Nevertheless, so that miniballs successfully placed, especially in
a tight formation, are not also extracted or dislodged,
stereotactic extraction is best reserved for a miniball
sufficiently distant from any others. However, the first discharge
is that most susceptible to miscalculation in the exit velocity, so
that the problem miniball will tend to be isolated. Also, to reduce
the risk of the miniball implants being pulled entirely through the
adventitia by the stent-jacket as would result in stent failure,
the tractive force applied to the miniballs is kept to the minimum
and evenly distributed by positioning the miniballs in a uniform
pattern as would tend to lift the wall as a sheet without the
tractive force concentrated on one or a few ductus-intramural
implants.
[1307] To accomplish uniform distancing between adjacent miniballs
at the small dimensions involved, especially at high speed to
minimize hypoxia, exceeds the precision that can be achieved under
manual control and therefore necessitates the use of an automatic
positional control system, as addressed in the section to follow
among others. Perforations can be prevented by preplacing the
stent-jacket. A miniball that perforates through a stent-jacket or
impasse-jacket encircled, or substrate, ductus on discharge or at a
later time due to pull-through becomes embedded in the moisture
barrier-coated viscoelastic polyurethane foam lining of the jacket
and is not a chronic irritant for the adventitia. More
specifically, were a miniball to pull through the adventitia to
become insinuated between the adventitia and the lining of the
stent-jacket despite the uniform positioning that deters
disproportionate traction on one or a few miniballs afforded by
positional system controlled discharge, then irritation to the
adventitia is at most short lived.
[1308] If the miniball remains aligned to the exit-hole, then
continued traction pulls the miniball away from the adventitia and
into the moisture barrier-coated viscoelastic polyurethane foam
lining of the stent- or shield-jacket, allowing the adventitia to
seal behind it. If gravity or movement of the surrounding tissue
causes the miniball move aside from the exit-hole, then the outward
force exerted by the adventitia and traction drive the miniball
into the lining. Embedded within the lining, the bioinertly
encapsulated submillimetric miniball is innocuous. Hence, once the
stent-jacket has been placed, the gradual pull-through of one or a
few miniballs is unlikely to produce chronic irritation or failure
of the stent.
[1309] Even without a stent-jacket prepositioned to prevent
perforation, the actual hazard posed by a miniball of millimetric
diameter that perforates is nugatory. Rebound into the lumen when
penetration into the base-tube is incomplete is addressed below in
the section entitled Double-wedge Stent- and Shield-jacket
Rebound-directing Linings. Provided the use of anticlotting
medication has not been excessive, a perforation through an artery
seals quickly, the prepositioned stent-jacket also absorbing any
minor leak. A change in moisture barrier-coated viscoelastic
polyurethane foam lining conformability due to the absoption of
blood which then dries and hardens is reduced by coating the inner
surface with enzymes and hydrogen peroxide. Potentially septic
leaks from the gut, for example, are treated conventionally by
suturing or cementing the perforation shut when the site is
approached to place the stent-jacket.
[1310] Perforations of the gut or vessels containing infectious
blood, for example, are implanted with stays, significantly
reducing the risk of perforations, or with miniballs with the
stent-jacket, a shield-jacket, or impasse-jacket within an
absorbable shield-jacket prepositioned over the segment to be
treated. Coating the internal surface of the stent-jacket with a
surgical cement or tissue sealant is not preferred as obviating the
conformability of the moisture barrier-coated viscoelastic
polyurethane foam lining desired to protect the microvasculature
and nervelets that enter and depart from the outer surface or
adventitia of the ductus. Provided the test prescribed below in the
section entitled In Situ Test upon Endoluminal Approach for
Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation is conducted, a perforation that occurred nevertheless
would require an error in adjusting the exit velocity or in having
selected points for testing that missed a transition to a softer
condition. Misaiming and improper setting of the exit velocity will
usually be the result of inadequate knowledge or skill.
[1311] Other causes can relate to airgun malfunctions, but with the
means for prevention provided, most causes will be the result of
human error. Airgun malfunctions are dealt with in the section
below entitled Modes of Failure. Given that the stent-jacket can be
prepositioned to preclude such an eventuality, the extent of the
diseased segment based upon testing can be confirmed through gross
inspection and the collateral use of contrast dye in imaging, and
can be further confirmed through the detection of fine differences
in temperature and electrical properties, misjudging the resistance
to perforation at the treatment site is unlikely. Unless
irradiated, a sterile and biocompatibly encapsulated miniball can
do no damage in the surrounding body cavity. The recovery of
radioactive and medication miniballs is addressed below. To injure,
much less puncture or penetrate a neighboring structure or
penetrate into the lumen of a neighboring ductus, the miniball
would have to retain the momentum needed.
[1312] Miniballs and stays can be coated with a cyanoacrylate
cement that quickly achieves an initial set to preserve wall
integrity pending healing. Whereas stays are coated as each is
ejected from the insertion tool, miniballs must not be coated with
a liquid glue until after discharge by injection using an injection
tool-insert or a hypotube-ended service catheter run through an
available barrel-tube used as a service channel following
placement. Midprocedural entry into the lumen is immediately
corrected using the recovery electromagnets in the muzzle-head of
the barrel-assembly, the embolic filter if the barrel-assembly is
so equipped and the filter is deployed, and a prepositioned
extracorporeal electromagnet. Mid- and postprocedural interception,
even in the circulation, such as might result from disease
progression or the contracting of a secondary condition, is
accomplished by the prepositioning upstream of an
impasse-jacket.
[1313] As can the primary stent-jacket, an impasse-jacket can also
be used at any later time for magnetic drug targeting. When
magnetic drug targeting would necessitate a field strength that
would pull the miniballs through the superjacent adventitia, the
magnetic susceptibility of the drug carrier particles is increased
by providing these with higher ferrous content. The midprocedural
loss of a miniball into a nonvascular lumen is instantly
correctible using the system components indicated. The
postprocedural extracton of a miniball stopped in the circulation
by an impasse-jacket is noninvasive, an external electromagnet
pulsed to extract the miniball from the jacket to a safe location
in increments or left energized to suddenly remove it from the body
altogether. The entry of a miniball into the gastroinstestinal
tract has little significance, and one loose in the airway or a
ureteter, for example, is quickly extractable at a clinic. When a
clinic will not be available, an impasse-jacket is placed.
[1314] Constant movement of the lumen wall is prevented from making
discharge or other treatment under direct manual control
excessively difficult by means addressed below in the section
entitled Gross Positional Stabilization (Immobilizaton) of the
Implant Insertion Site. Up to the peak systolic diameter, the
cross-sectional area of the lumen not taken up by the muzzle-head
will be available for blood to pass, and the barrel-assembly
incorporates blood passing features, as addressed below in sections
respective of each and summarized in the section entitled Hypoxia
and Ischemia-averting Elements. Discharge is effected during
diastole, the systoles used to reposition the muzzle-head. However,
as prepositioning and tightening the stent-jacket may be used when
an arrhythmic (irregular) or tachycardic (accelerated) pulse makes
timing discharge difficult, the muzzle-head must be of an outer
diameter that allows it to be repositioned with the stent-jacket
tightened.
[1315] While some oxygenated blood is able to pass whether the
muzzle-head is stationary or in motion, ischemia will limit the
narrowness of the vessel that can be treated; however, small
vessels do not develop plaques. Reduction in diameter or length of
the muzzle-head will reduce it as an obstruction to the flow of
blood but reduce the angioplasty and atherectomy components it can
incorporate. Reduction in size will also reduce the maximum
diameter or number of barrel-tubes, hence, the number of miniballs
that can be discharged simultaneously, which factor reduces the
implantation rate. It will also require the turret-motor windings
to be increased in length in order to generate a given torque
output, and reduce the maximum field strength that can be developed
by the recovery electromagnets, whose windings are not amenable of
lengthening.
[1316] This is because in any barrel-assembly for use in the
bloodstream, the recovery electromagnets must be distal to the
exit-ports. Lengthening these lengthens the nose and thus reduces
the forward reach of the muzzle-head, that is, reduces the distance
to which the exit-ports can be advanced down a narrowing vessel to
align the exit-ports with tissue to be implanted. With a
monobarrel, which is suited to use in more narrow vessels,
positioning the exit-port against the arc to be implanted distends
the wall in contact with the muzzle-head to no more than its
systolic displacement, with the luminal cross-section for blood to
pass shifted toward the arc not in contact with the muzzle-head.
This allows relative movement between the muzzle-head and the wall
to be suppressed stabilizing (immobilizing) the lumen wall during
discharge while increasing the passage of blood past other
side.
[1317] The temporary stabilization of the lumen wall at the
treatment site also allows ablation or brush cytology, for example,
to be accomplished and avoids the difficulties and uncertainties of
synchronizing discharge to the pulse. Abaxial angular shifting of
the muzzle-head and applying pressure against the lumen wall can be
aided by radial projection unit push-arm tool-inserts, an external
magnet, or an inmate steering system. For the purpose of
stabilizing the wall to implant it, this urging is best kept least
compressive as possible. The use of these is, however, primarily
intended as an aid to angioplasty or atherectomy. The external
electromagnet, which can be hand-held, attracts the cores or
armatures in the muzzle-head, which unlike the silver windings,
must be ferromagnetic.
[1318] For use in the bloodstream, resistance to the advancement of
the miniballs by the air trapped in the barrels demands pressure
relief to prevent air or propulsive gas, normally CO.sub.2, from
entering the bloodstream during discharge. It is also important to
minimize any inflow of blood into the muzzle-head through the exit
ports during the intervals between discharges. In vascular
applications, the ballistic implantation of miniballs, whether as a
method for introducing medication, a radionuclide, and/or other
therapeutic substances, and/or as the intravascular component of an
extraluminal stent, usually follows an angioplasty or atherectomy,
whether thermal, cryogenic, or mechanical. An angioplasty-capable
barrel-assembly can be used to apply any of these and then be
engaged within the interventional airgun to effect discharge
implantation without the need for withdrawal.
[1319] When stenting is to be direct, or not preceded by an
angioplasty as not to require entry into the lumen, then the use of
stays rather than miniballs allows the lumen to be avoided for
stenting as well. When stays are used to target medication,
radiation, and/or for stenting so that the lumen is avoided, the
need for platelet blockade is periprocedural and eliminated shortly
thereafter. With ballistic implantation, the thrombogenic period
associated with intimal healing is longer, so that antiocoagulative
medication is given longer. However, once healed, no stent occupies
the lumen, and this medication is stopped. Otherwise, the methods
described herein warrant the perioperative management prompted by
transluminal procedures.
[1320] This includes medication for managing the sequelae normally
associated with catheter-based procedures, such as the
administration of a calcium antagonist to reduce risk of coronary
artery spasm. Whereas relaxation in an artery is associated with
contraction, in peristalsis, expansion is associated with
relaxation or distention due to the passage of a large bolus. While
the timing and form of peristalsis in different type ductus such as
the gastrointestinal tract and ureters differs, for a certain
target location, the muzzle-head is repositioned during
contraction, with discharge effected at the moments of relaxation.
Means for facilitating implantation whether under direct manual or
semiautomatic control are addressed below in the section entitled
Motional Stabilization of the Implant Insertion Site.
11. Use of a Positional Control System
[1321] The use of a stepper motor to advance a catheter goes back
at least to the mid-1970s (see, for example, Clark, J. S. and and
Fan, F. L 1978. "Alveolar Gas Sampling System and Method," [U.S.
Pat. No. 4,220,162]; Bradley, W. E Klatt, W. M., Kuyava, C. C., and
Dreher, R. D. 1980. "Urethral Catheter Puller," [U.S. Pat. No.
4,233,991], and a catheter-based transducer through the lumina of
vessels at millimetric intervals was accomplished not later than
1994 (Matar, F. A., Mintz, G. S., Douek, P., Farb, A., Virmani, R.,
Javier, S. P., Popma, J. J., Pichard, A. D., Kent, K. M., Satler,
L. F., Keller, M. and Leon, M. B. 1994. Coronary Artery Lumen
Volume Measurement Using Three-dimensional Intraductal Ultrasound:
Validation of a New Technique," Catheterization and Cardiovascular
Diagnosis 33(3):214-220; Liu, J. B., Bonn, J., Needleman, L.,
Chiou, H. J., Gardiner, G. A. Jr., and Goldberg, B. B. 1999.
"Feasibility of Three-dimensional Intraductal Ultrasonography:
Preliminary Clinical Studies," Journal of Ultrasound in Medicine
18(7):489-495).
[1322] The application of a positional control system to the
transluminal and rotatory control of a catheter as an aid to
intravascular or endoluminal intervention, however, does not appear
in the literature. Since the degree of precision needed for
conventional procedures is less, this is to be expected. To the
extent possible, the object is to have multiple implants together
lift the lumen wall as a uniform sheet, so that even though magnet
pole foci of attraction exist, the force of attraction on any one
implant, even at the magnetic poles or apices of the foci, will not
be sufficiently disproportionate to pull implants through or tear
the adventitia and media if implanted therein, or prompt an
avoidance of placing implants within areas of focal field
intensity.
[1323] For placing miniballs to serve as the intravascular
component of a magnetic extraluminal stent, a close and uniform
spacing of miniballs more evenly distributes the magnetic traction,
reducing the likelihood for pull-through. To achieve fine
incremental repositioning with uniform spacing, much less quickly
to minimize procedural time, exceeds manual ability even with the
benefit of high resolution imaging equipment. Another application
for implants in tighter formations is to allow implants that
consist entirely or peripherally of medication and/or radionuclide
miniballs (radiation emitting seeds) to deliver a higher dose over
a circumscribed area. However, precisely uniform spacing is not
essential for these, the absolute distance between adjacent
miniballs will be larger, and the sum of these will usually be
relatively few in number.
[1324] Another use for fine control over the positioning of
implants is to make possible the dispersal of miniballs so as to
minimize the resistance to penetration of medication through
atherosclerotic or neoplastic tissue (see, for example, Ghosn, M.
G., Carbajal, E. F., Befrui, N. A, Tellez, A., Granada, J. F., and
Larin, K. V., 2008. "Permeability of Hyperosmotic Agent in Normal
and Atherosclerotic Vascular Tissues," Journal of Biomedical Optics
13(1): 010505; Larin, K. V., Ghosn, M. G., Ivers, S. N., Tellez,
A., and Granada, J. F., 2007. "Quantification of Glucose Diffusion
in Arterial Tissues by Using Optical Coherence Tomography, Laser
Physics Letters 4(4):312-317). The character of the tissue to be
implanted determines the dispersal pattern as to uniform,
nonuniform, concentrated at or about a focal point, or some
combination thereof. The distribution at controlled interrelated
distances throughout a tumor, for example, of miniballs that
release various drugs, combinations of drugs in various doses,
other therapeutic substances and/or radiation avoids the need for
diffusion through the circulatory system.
[1325] The object therewith is to establish a local or more
extended field for the placement of medication or other therapeutic
miniballs in a pattern that will compensate for an impeding
delivery diffusion gradient. Each miniball releases a dose or
radiation dose-rate that is taken up proportionally less as it
diffuses away from the point of origin or focal source. Dissolution
or disintegration of medication implants can be by conventional
time-release formulation or by extracorporeal action at intervals
based upon periodic diagnostic results, as addressed in the section
below entitled Extracorporeal Energization of Intrinsic Means for
Radiating Heat from within Medication Implants and Medication
and/or the Tissue Bonding-coatings of Implants, to Include
Miniballs, Stays, and Prongs, such as to control the dissolution
thereof.
[1326] When miniballs for stenting are medicated, uniformity of
distribution takes precedence; if a focused gradient for the
associated medication is desired, then the dose applied to the
miniballs is progressively reduced moving outward from the focal
center. It is simpler to adjust the dose in each miniball than to
implant an intricate formation. While the endoscopic placement of
irradiating seeds in the gastrointestinal tract has long been
practiced, implantation by the means described herein is more
precise and allows individual seeds to be placed in close proximity
through trajectories or entry paths that no larger than the
implants themselves, quickly seal and heal. The delivery of
medication other than by injection allows considerably greater
control over the area exposed to the drug and the delivery rate.
The release of medication can be time delayed and the density of
implants can be used as one way to control the dose.
[1327] A related but distinct purpose for using an automatic
positional control system is to place the exit velocity as well as
the linear stage and turret-motor under control, thus making
possible side-looking discharge of medication and/or radiation seed
miniballs at a high rate and in a pattern of variable depth and
sidewise or abaxial deviation. Miniballs for uniform placement are
almost always implanted within uniform tissue without the need to
adjust the exit velocity from one to the next. If needed, the
adjustments are accomplished manually. The distribution at
controlled relative distances throughout a tumor, for example, of
miniballs that release various drugs, combinations of drugs in
various doses, other therapeutic substances and/or radiation is
presaged in the carcinolytic radioactive seeding of organs, the
prostate gland being that most familiar. Use thus essentially adds
depth of penetration as the third dimension to the two dimensions
involved in achieving uniform distribution to the same depth within
the lumen wall.
[1328] For tumor-seeding, the pattern of placement in depth and
lateral displacement is the object, with uniform distancing but one
possible pattern of distribution sought. For drug and/or radiation
tumor-seeding, the barrel-assembly is usually a monobarrel, or one
with only a single barrel-tube, and achieving a certain pattern of
distribution in depth and lateral displacement is the object. The
distribution pattern is based upon the constituents of the
miniballs, with uniform distance but one possible pattern. Once
implanted, each miniball releases its medication or other substance
within the tumor at a predetermined distance from the others, and
the contribution of each may relate to that of the others as
providing dose uniformity, a combined effect, or adjuvant action,
usually, in proportion to the relative proximity of each to the
others. Since the barrel-assembly uses the lumen as its track so
that endoluminal containment stabilizes the muzzle-head in position
relative to the atheroma or neoplasm, the concept pertains
primarily to tumors of ductus or vessel walls.
[1329] When judged unsuitable for immediate excision, as in late
stage metastatic disease or when chemotherapy and/or radiation are
thought capable of effecting a cure, such lesions include
colorectal and extrahepatic bile duct carcinomas, secondary
metastases to blood vessels, and other periductal tumors which have
depth, are relatively small, and/or awkwardly situated for access
with an endoscope (which is not capable of the treatment modality
indicated in any event), and tend to resist penetration or
infiltration by medication (see Qiao, Y., Huang, X., Nimmagadda,
S., Bai, R., Staedtke, V., Foss, C. A., and 9 others 2011. "A
Robust Approach to Enhance Tumor-selective Accumulation of
Nanoparticles," Oncotarget 2011 2(1-2):59-68; Baish, J. W.,
Stylianopoulos, T., Lanning, R. M., Mamoun, W. S., Fukumura, D.,
Munn, L. L., and Jain, R. K. 2011. "Scaling Rules for Diffusive
Drug Delivery in Tumor and Normal Tissues," Proceedings of the
National Academy of Sciences of the United States of America
108(5): 1799-1803; Tredan, O., Galmarini, C. M., Patel, K., and
Tannock, I. F. 2007. "Drug Resistance and the Solid Tumor
Microenvironment," Journal of the National Cancer Institute
99(19):1441-1454; Kyle, A. H., Huxham, L. A., Yeoman, D. M., and
Minchinton, A. I. 2007. "Limited Tissue Penetration of Taxanes: A
Mechanism for Resistance in Solid Tumors," Clinical Cancer Research
13(9):2804-2810; Minchinton, A. I. and Tannock, I. F. 2006. "Drug
Penetration in Solid Tumours," Nature Reviews. Cancer 6(8):583-592;
Grantab, R., Sivananthan, S., and Tannock, I. F. 2006. "The
Penetration of Anticancer Drugs through Tumor Tissue as a Function
of Cellular Adhesion and Packing Density of Tumor Cells," Cancer
Research 66(2):1033-1039; Tannock, I. F., Lee, C. M., Tunggal, J.
K., Cowan, D. S. M., and Egorin, M. J. 2002. "Limited Penetration
of Anticancer Drugs through Tumor Tissue: A Potential Cause of
Resistance of Solid Tumors to Chemotherapy," Clinical Cancer
Research 8(3):878-884; Lankelma, J. 2002. "Tissue Transport of
Anti-cancer Drugs," Current Pharmaceutical Design
8(22):1987-1993).
[1330] Provided a motorized positioning system is available, the
implantation of nonstenting miniballs can benefit from
semiautomatic discharge when this added capability is available,
but if not, these can be precisely targeted manually on an
individual basis. That is, while both stenting and nonstenting
discharge benefit from semiautomatic machine control support,
precise positioning of the airgun exit-hole or holes usually
demands a degree of precision and speed that necessitates automatic
support where the discharge of medication miniballs or postioning
of tool-inserts for an angioplasty, for example, do not.
Accordingly, for higher density implantation at a higher rate,
machine support must afford the additional capability of
semiautomatic discharge sequencing keyed to transluminal or linear
stage and rotatory or turret-motor displacement whereby the
operator can trigger a uniformly spaced pattern of miniballs at one
time rather than the discharge of a single miniball or shot-group.
The need for an automatic positional control system is thus not
created by a need for close spacing in general but rather uniform
close point to point spacing at a high rate.
[1331] The controls provided for the operator are addressed below
in the sections entitled Ablation and Ablation and
Angioplasty-capable Barrel-assembly Onboard Control Panel and
Barrel-assembly Power and Control Housing, among others. Antecedent
to any use of automatic control, the stepper motor-driven linear
positioning stage or table is signalled to advance or retreat and
the turret-motor to assume a rotatory angle in timed coordination
with the successive discharges of an interventional airgun or if
precise motional control is necessary, for positioning a
tool-insert injector or abrader, for example. The airgun is mounted
on a linear positioning stage, which typically allows continuous
movement of about 15 centimeters without the need for
repositioning. This distance is generally greater than that needed
to move from one lesion to the next over the affected segments of a
vessel but may be needed when the benefit of additional angioplasty
or the administration of a drug by injection tool-insert, for
example, becomes apparent after miniball discharge has been
intitiated.
[1332] The airgun settings for moment of discharge, and when
adjusted, the exit velocity, are controlled as auxiliary functions
of the automatic positioning control system. At normal
(nontachycardic) heart rates to which the operator or an assistant
can respond manually, complex synchronization circuitry such as
that incorporated in cardioverter defibrillators or the use of
imaging machines (see, for example, Souchon, R., Gennisson, J. L.,
Tanter, M., Salomir, R., Chapelon, J. Y., and Rouviere, O. 2012.
"Measurement of Pulsatile Motion with Millisecond Resolution by
MRI," Magnetic Resonance in Medicine 67(6):1787-1793), for example,
should not be needed. If the area for secondary or touch-up
treatment is more extended, then repositioning can be accomplished
by disengaging the barrel-assembly from the airgun freeing it for
independent manual advancement or withdrawal, then reinserting it
in the airgun.
[1333] Provided the view afforded is adquate, direct manual control
of the linear (transluminal) stepper and turret motors will usually
allow fine adjustments in position sufficient for precise such
miniball targeting or injection by an injector tool-insert, for
example, without the aid of a positional control system much less
one under automatic control. As one factor in reducing procedural
times, rotary magazine clips that provide ten or more discharges of
four or more shots to the shot-group per discharge, for example,
support the loading requirements for high-density implantation.
However, even with multiple implants delivered per discharge, to
minimize intraluminal time also requires speed and accuracy of
discharge while, moreover, withdrawing or advancing the
barrel-assembly by quick steps.
[1334] This, and if necessary, the release from injection
tool-inserts of a lubricant and/or nitric oxide, serve to minimize
any tendency toward endothelial cling (adhesion) or impedance from
encroachment against the sides of the muzzle-head by the lumen wall
as could result in stretching injury if not a perforation.
Semiautomatic discharge consists of the operator manually
triggering a sequence of discharges that proceeds automatically.
During stenting miniball discharge, to achieve uniform positioning
of implants in a close formation, the control of transluminal
positioning, whether discharge is triggered manually or
semiautomatically, is generally relegated to a linear positioning
stage, and rotatory positioning to the turret-motor. Due to the
small angular adjustments that may be required, semiautomatic
discharge usually includes control over the turret-motor.
[1335] In arteries, stays are inserted on the systoles, miniballs
on the diastoles. The rate of discharge is not significantly
impeded when the immediately preceding miniballs or sequence
thereof must be allowed to seat, or reach the trajectory end-points
or termini during a diastole, before the following discharge is
triggered on the next diastole. The coordinated use of imaging
equipment and resynchronization technology makes possible the
automatic synchronization of discharge to the pulse or peristalsis;
however, even without means for adapting to the physiological
action when arrhyhtmic (erratic), to do this necessitates a level
of complexity and expense that should seldom prove necessary.
Repositioning of the muzzle-head over distances of several
centimeters is usually accomplished manually whether the
barrel-assembly remains inserted in the airgun barrel.
[1336] When the condition of the lumen wall is nonuniform, each
discharge is confirmed as satisfactory before proceeding to the
next. When the lumen wall is uniform, the discharge sequence,
usually that provided by the rotary magazine clip, is confirmed.
Each rotary clip can completely change the type and number of the
miniballs, no two of which need be the same except in caliber,
those of the barrel-tubes not changeable midprocedurally without
withdrawal and reentry. Whether the miniballs are discharged
manually or semiautomatically, to allow the immediate application
of remedial measures in the event of a mishap, it is preferred that
each discharge or discharge sequence be visually confirmed as
having been properly placed before proceeding to the next
discharge.
[1337] When the stent-jacket or segmental stent-jacket is
prepositioned to prevent a perforation, imaging includes an
endoluminal viewing device, such as a fiberoptic endoscope or
angioscope built into the barrel-assembly or inserted through the
central channel of a combination-form barrel-assembly to emerge
through the nose-hole thereof. A fine gauge intravascular
ultrasound catheter can be incorporated thus but is costly. These
are described in the section below entitled Types of
Barrel-assemblies. The rate of sequence discharge is not
significantly affected by barrel-tube transit time or the transit
therein of two or more miniballs therethrough at the same time. For
simplicity, the section below entitled Positioning of the
Muzzle-assembly with the Linear Positioning Table and Turret-motor
recommends a pulse synchronization that is most comfortable to the
operator based upon the available view.
[1338] While food intake can be stopped in advance, and drugs are
available to reduce or stop movement in the gut, peristalsis is
usually not so fast as to thwart calculating predictive discharge.
The specific procedure as including implant insertion, ablation, or
injection, for example, will determine whether the flaccidity of
drug induced enteroparesis or the tonus sustained by its avoidance
will best serve. To accomplish fine incremental advancement or
withdrawal, the patient and barrel-assembly are positioned on the
same height from the floor as the airgun barrel. A
semiautomatically operated single-axis linear positioning stage or
linear positioning table with the airgun to mounted atop it is used
to withdraw or advance the barrel-assembly by a distance
(increment, interval) with each discharge, usually the same
distance.
[1339] When discharges follow in rapid succession, implantation
follows each triggering of the airgun by the short interval that it
takes for the projectile implants to transit the barrel-tubes and
reach the trajectory end-point. Incremental movement of the linear
positioning table and discharge need not be detained for each such
recurrence. For simplicity and safety, successive manual triggering
of each discharge and incrementing of the table are timed to
confirm the proper seating of the implants before continuing.
Discharge when the ductus is relatively quiescent reduces the
continuous fluctuations in target position and mechanical
properties but a flaccid condition that equates to laxness of the
smooth muscle can effectively reduce the hardness and penetrability
of the tissue.
[1340] When used in an artery, greater control and precision is
attained when discharge occurs during the end-diastoles than when
the wall expands during systoles, which intervals expedite and are
used for repositioning of the muzzle-head and allowing blood to
pass. In smaller vessels, the limited number of barrel-tubes that
can be used underscores the value in automated positional control
for optimizing the rate of discharge as well as achieving precision
in close formation of the implants at a much higher rate than might
be achieved by manual targeting, thus minimizing the risk of
inducing ischemia during implant delivery. The synchronization of
implantation to the intrinsic motility in the ductus during
discharge of the airgun under direct manual control is facilitated
through means addressed in the section below entitled Stabilization
of the Implant Insertion Site.
[1341] The positional control to be described is primarily used to
execute brief, usually repetative, point-to-point discharge-move
(advance, withdraw, and/or rotate)-discharge patterns with a
dimensional resolution that exceeds manual ability. Otherwise, the
apparatus is fully responsive to the instant command of the
operator, who triggers the execution of each such pattern. Control
thus is semi-rather than fully automatic. Fully automatic control
is seldom employed as relinquishing operator discretion, and as
with any machine action, can be halted instantly by pressing the
cancel or `kill` switch on the control panel. The action can then
be resumed where it was left off or terminated.
[1342] Because both the implants and stent-jacket are inserted
through the same small incision, `direct stenting` of an
atheromatous artery or a partially encrusted ureter, for example,
by implanting stent-stays without endoluminal preparation through
ablation, atherectomy, or an angioplasty, eliminates the need for a
transluminal procedural component altogether. A test for wall
strength is provided below in the section entitled Testing and
Tests. Concerns for a lumen wall that having been angioplastied
requires support to preserve patency but is too weak to withstand
outward retraction is to avert implant pull-through or a rupture by
placing a magnetic stent-jacket coated internally with a surgical
cement or tissue sealant first and using broad cyanoacrylate coated
stent-stays instead or deferring ballistic implantation to a later
date. A cement almost in the internal environment is broken down
over time; however, this should allow sufficient time for
healing.
12. Concept of the Impasse-Jacket
[1343] Impasse-jackets, addressed below in the section entitled
Miniball and Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets, are magnetized collars for prepositioning about a
ductus to trap loose, or to hold, a miniball or microspherules in
the bloodstream or along the digestive or reproductive tract, for
example, or to attract magnetic drug or radionuclide carrier bound
nanoparticles from the passing lumen contents, usually blood. That
an impasse-jacket will stop any magnetically susceptible matter
means that drugs and/or others pharmaceuticals or therapeutic
substances can be delivered to it in any combination in any
sequence. As is true of stent-jackets used with stays and
clasp-jackets, impasse-jackets are placed without endoluminal
entry. The potential applications of impasse-jackets to reduce the
risk of occlusion which the family history and genome indicate that
risk approaches certainty is high are many.
[1344] For example, the prepositioning of impasse-jackets on the
carotids of adlolescent heterozygous familial hypercholesterolemics
and sitosterolemics, or phytosterolemics, to locally release a
statin thereby supplementing the systemic with a concentrated local
dose, can be used to reduce the risk of stroke while avoiding a
systemic level that induces adverse side effects. Such direct
delivery to an affected segment, for example, takes advantage of
the nonhepatic benefits afforded by statins as addressed above in
the section entitled Drug-releasing and Irradiating Miniballs,
Stays, and Ferrofluids, among others, and may avert the need for an
endarterectomy in later life. If a reversal agent is necessary, a
downstream impasse-jacket is used to release 3-hydroxy
3-methylglutaryl coenzyme A reductase to take up any residual
portion of its inhibitor.
[1345] An impasse-jacket can be positioned upstream of a
stent-jacket to release a statin or other therapeutic substance to
flow over the lumen wall thereby to treat the stented segment. The
releasant if drug carrier nanoparticle bound is drawn into the
stented segment; if not, then the statin flows over the stented
lumen surface. If a statin, then any residue can be allowed to add
to the systemic dose, or if to be neutralized, then a second
impasse-jacket downstream from the stent-jacket can release
3-hydroxy-3-methylglutaryl-coenzyme A reductase as a reversal agent
to take up the inhibitor, as well as stand positioned to trap any
miniball that might enter from upstream. Analogous applications are
numerous. Unless fully charged or loaded, any holding jacket will
trap a passing miniball, and any trap-jacket with the loading space
available can be used to release medication as a holding
jacket.
[1346] In most if not all such applications, the last, or reversal
agent-releasing, and trap-jacket jacket is implanted first. To
avert migration without constricting the substrate ductus, the
impasse-jacket is selected for an internal diameter that matches
the quiescent or end-diastolic outer diameter of the artery or
other type ductus, closes under the restorative force of a
spring-loaded hinge, and is lined with nonbiodegradable or
bioresistant viscoelastic polyurethane moisture barrier-coated
viscoelastic polyurethane foam. The impasse-jacket thus expands and
contracts with the substrate ductus, as do stent-jackets,
clasp-wraps, and magnet-wraps. Impasse-jackets differ from
stent-jackets in attracting miniballs against rather than within
the lumen wall. Impasse-jackets used protectively to interdict a
loose miniball in the bloodstream from embolizing downstream or
limit the transit of a medication miniball that should not be
allowed past a certain level are trap-jackets.
[1347] Holding jackets will retain a `smart pill` or miniball for
the targeted release of a drug or drugs at a later time when needed
by external control, magnetic, electromagnetic, microwave, or the
ingestion, injection, or infusion, such as central venous or
subclavian, of a triggering substance. Those used for medicinal
rather than protective purposes catch and hold medication miniballs
delivered through the lumen are structurally the same of very
similar and referred to as holding jackets. The distinction between
trapping and holding is intended only to indicate a primary
function; trap-jackets hold, and holding jackets trap, but some
trap-jackets are intended only to trap, and so on. The ability to
target a drug therapeutically also constitutes an in vivo
pharmacological development test for the effect of the drug on a
particular normal or diseased tissue organ, or a tumor.
[1348] Magnetic components such as impasse-jackets can be used to
target a segment of a ductus or an organ for the receipt or the
sequestration (isolation) from a particular drug or other
therapeutic substance. The impasse-jacket is configured to allow
the trapped or suspended medication and/or radiation releasing
miniball to be noninvasively extracted at any time by a powerful
extracorporeal magnet, usually with relatively short term and
minimal interference with the intrinsic action in the ductus. In a
blood vessel, an impasse-jacket serves to trap a loose miniball
from continued movement through the circulation and/or acts to draw
magnetic drug carrier particles from the blood into the wall of the
lumen it encircles. An impasse-jacket placed about an incipient or
early stage aneurysm will both restrain its enlargement and serve
as a drug releasing point.
[1349] Placement along the arterial tree sets the territory
supplied with the drug, so that placed about the aorta, the
systemic circulation carries the drug to the body with little sent
to the lungs, whereas placement about the pulmonary artery targets
the lungs. Similarly, placing the jacket about the superior or
inferior mesenteric artery would target the portion of the gut
supplied. Depending upon whether the drug is dissolubly bound to
the drug carrier nanoparticle, it can be drawn into the wall or
released into the circulation. Aeurysms are exceptional in
susceptibility only to systemically distributed antihypertensives,
beta and/or angiotensin II receptor blockers with a statin helpful
from the standpoint of lowing blood fats; however, most
nonaneurysmal lesions affecting ductus can be locally targeted.
[1350] Impasse-jackets can be made to be absorbed when no longer
needed. In an absorbable impasse-jacket, the extraction grid is
made of a magnesium alloy of appropriate life in the internal
environment, magnetization is by means of chemical
isolation-encapsulated granular neodymium lanthanoid that will be
innocuous when a residue, and the moisture barrier-coated
viscoelastic polyurethane foam is treated to encourage
disintegration by the immune system. An absorbable impasse-jacket
such as one placed to suspend medication miniballs at a certain
level over a limited period is, however, the exception; most must
remain to guard against future embolization should a stenting
miniball enter the bloodstream as the result of a direct blow, for
example, or the jacket may need to be recharged with medication
miniballs for an indeterminate period into the future.
[1351] Direct lines to impasse-jackets and/or their outriggers or
dummy collars from the body surface is addressed below in the
sections entitled Direct Lines from the Body Surface to and from
Impasse- and Other Type Jackets and Single and Plural Circuit
Pumping through Direct Lines to Jackets. Stent-jackets can also
trap and retain susceptible mniballs or a ferrofluid to interdict
further passage or allow spontaneous or controlled release of the
contents; however, these do not incorporate a grid or grate barrel
that allows the use of a powerful magnetic field to extract the
susceptible matter to a position outside the ductus, and most exert
field strength only sufficient to exert the minimum tractive force
on the miniballs used to preserve luminal patency without tunical
delamination or pull-through. Miniballs in noncirculatory ductus
are readily recoverable, so that the use of impasse-jackets as
traps is substantially confined to the circulatory system.
[1352] Unlike impasse-jackets, stent-jackets are not configured to
allow the noninvasive removal of a suspended miniball or
microsphere at any time. The perforated collar required disallows
the addition of a radiation attenuating shield, for example.
Medication and/or time-release medication miniballs, microspheres,
drug carrier particle-containing ferrofluid, or spherules
containing these always include sufficient ferrous content to
assure recoverability. These are infused or injected directly into
the bloodstream upstream to the jacket. For use in the digestive
tract, this material is swallowed. A medication miniball or
microsphere intentionally directed to and held suspended in an
impasse-jacket may be used to initiate the release of a
ferrous-unattached drug or other therapeutic substance into the
circulation at that level, or to release magnetic drug-carrier
particles for direct attraction into the surrounding lumen wall by
the impasse-jacket that encircles the wall.
[1353] Impasse-jackets and stent-jackets that can be used as
suspension or holding jackets can be used to trap ferrofluid-bound
drugs and/or radionuclides, and encapsulated microspheres or
miniballs incorporating these approaching through the bloodstream.
Release of a drug from a microsphere or miniball can take any of
numerous forms, to include time separated dissolution of the shells
thereof, and can do so in response to a number of inducing
conditions ranging from the mere flow of blood to the injection of
a breakdown or dissolution agent, and/or the application of heat.
When prepositioned to inhibit a disease of known course from
spreading, a drug held within the lumen encircled by an
impasse-jacket can be activated at any later time to serve a
preventive, abating, or palliative function.
[1354] Since an unmetered or abrupt filling (loading, charging) of
a holding jacket by a large number of miniballs might obstruct it,
the medication is ordinarily concentrated in small sphericles,
vesicles, or a fluid vehicle. Like stent-jackets, impasse-jackets
can be chained, with each sub jacket selected for the segment of
the ductus will appose and treat before it is connected into the
chain, and a chain can incorporate both stent-jackets and
impasse-jackets thereby gaining the special capabilities of either
type jacket as specified above in the section entitled System
Implant Magnetic Drug and Radiation Targeting, among others.
Midprocedurally, an impasse-jacket prepositioned upstream from the
treatment site can be used to intercept a miniball loose in the
bloodstream, and when necessary, an external electromagnet with
probe directed toward the impasse-jacket can be used to extract the
miniball or other ferrous matter containing contents intercepted
and held by the jacket.
[1355] The field strength exerted by the jacket-centered
semicircumferentially magnetized magnet or magnets is chosen for
the least magnetically susceptible miniball or drug carrying
microsphere or particles to be stopped. Because the suddenness of
extraction does not allow the miniball to pull at and tear away
adjacent tissue, even when an external magnet alone is used to
extract a miniball loose in the circulation, the exit perforation
through the lumen wall will be relatively `clean` and little if at
all productive of debris. By framing about the miniball, the grid
of an impasse-jacket further protects the tissue surrounding the
extraction trajectory from stretching injury. The cellular exudate
released and any neighboring body fluid spontaneously seal the
perforation. The risk of thrombosis is reduced by coating the
miniball with platelet blockade and usually, administering a
systemic antithrombogenic agent.
[1356] Miniball interception and suspension within a trap-jacket
does not equate to a need to extract the miniball; when there is no
interference with circulation and the strength of retention is
sufficient, the miniball can be left in the jacket interminably or
for removal at a later date. Much of the utility of impasse-jackets
will be realized as a result of the ongoing development of orally
administered magnetically susceptible carrier nanoparticle-bound
drugs. As opposed to the injection of a ferrofluid and use of a
powerful external electromagnet to draw the drug carrier particles
into the tissue to be treated, an immediately prepositioned
magnetized jacket is present continuously, dispensing with the need
for a properly adjusted extracorporeal magnet available only at a
clinic; however, regardless of the magetic source employed, drug
administration that requires injection or infusion will continue to
depend upon self-administration through a subcutaneously implanted
portal or tie the patient to the clinic.
[1357] Until orally administered magnetically and/or metabolically
targeted drugs appear, administration is usually by upstream
injection directly into the artery or other ductus. How close to
the stopping point the medication is introduced is determined by
the rate of spontaneous dissolution if applicable, the degree of
invasiveness required, and the benefit in avoiding the upstream
circulation. Except in an open surgical field, the extravascular
implants described herein such as impasse-jackets are introduced
through a laparoscopic stab or `keyhole` incision. By minimizing
stretching about the exit-hole, the wire grid-surround favors clean
extraction. The grid-surround should not be so elastic as to
collapse or the grid perforation borders so lacking in stiffness
(rigidity) or elastic as not to further suppress stretching injury
during extraction.
[1358] However, this necessitates that it be sufficiently robust to
not collapse under the pull of the extraction electromagnet. This
strength requirement has no effect on small impasse-jackets, which
are inserted with the length normal to and through a keyhole
incision. However, to collapse for insertion through a small
incision, a large impasse-jacket, such as one with an internal
diameter of 7 centimeters for placement about the colon, must be
collapsible. The simplest resolution for these contradictory
requirements is to insert the the grid-surround with end bumpers
through the entry incision as four cylindrical quadrant hinged
bifolds that are placed to progressively encircle the ductus by
connection together with hinges. Once completed, the cylinder is
encircled by hinged snap rings (hinged key rings, looseleaf book
rings) held in channels continuous around the bifolds once
assembled about the ductus.
[1359] Whether an impasse-jacket or a stent-jacket, when made of
material intrinsically magnetized, each half cylinder is magnetized
by rotation before the magnetizer separately; continued rotation of
a complete cylinder would partially demagnetize the opposite half
cylinder. Unlike magnetized miniballs and stays, addressed above in
the section entitled Drug-targeting Miniballs and Stays, which can
be used to like purpose, an impasse-jacket eliminates the need to
introduce implants ductus-intramurally. This factor makes it
possible to use impasse-jackets with tissue too weakened by
diseased to retain these. The impasse-jacket can be used to draw
any therapeutic substance, such as a tissue hardener,
ductus-intramurally. In situ tests for ductus wall strength are
addressed below in the section entitled Testing and Tests.
[1360] Once placed, the jacket is positioned for any later
administration of suitably formulated medication or other
therapeutic substance, such as a radionuclide, hormone, or enzyme.
The same is true of a stent-jacket, which lacking suitable openings
does not, however, permit miniball extraction, cannot incorporate a
radiation shield for use with a radionuclide of high dose rate, and
generally must exert less magnetic strength for stenting. Since the
wire grid surround must allow the use of an external magnet to
extract a miniball held within the jacket without collapsing
despite its opposing polarization, and making it of stock that is
rectilinear in cross section could result in the catching hold and
trapping of a miniball on the adluminal face, a rounded interface
is used.
[1361] Similarly to the magnets mounted about the base-tube of a
stent-jacket, the impasse-jacket grid surround is magnetized
axipetally (radially, centripetally) to its central longitudinal
axis, which will be that of the lumen to be encircled. With
intrinsically magnetized stent and impasse-jackets, thickness,
flexibility, and magnetized face contour must be coordinated.
Increasing the thickness of the magnetized portion of the jacket
reduces flexibility and may necessitate machining longitudinal
furrows to allow the degree of flexion needed. For ease of
manufacture, intrinsically magnetized stent and impasse-jackets are
made of sheet stock with the perforations punched therein, then
rolled to produce the side-slitted or -slotted cylinder. The flat
but rounded conformation is more effective for reducing stretching
of the tissue surrounding the exit trajectory but less effective
for exerting tractive force.
[1362] The interposition of a moisture barrier-coated viscoelastic
polyurethane foam lining between the adventitia and the internal
surface of the jacket allows flat-faced slats or stock generally
pyramidal with the apices directed toward the long axis of the
lumen to be applied internally but adds expense. The gauge of
cylindrical stock in a practical grid must support the magnetic
strength required; the wire grid shown in FIG. 16 conforms to the
performance conditions required at the treatment site for which it
is intended. By placing the patient in an alternating magnetic
field, ductus intramurally implanted medication or medicated
miniballs and miniballs suspended in the bloodstream in an impasse
or stent holding jacket containing magnetically susceptible nano-
or microparticle-bound drugs can be heated. Thus, depending upon
the specific drugs, any coatings, and/or the medium in which the
drugs are suspended, the dissolution temperature can be raised to
control or accelerate the release of each drug.
[1363] Unless thermally -insulated by a polymeric coating, the
magnetic material of stent- and impasse-jackets and the mesh of an
impasse-jacket when magnetically susceptible will also warm the
ductus from the outside. Upon cessation of the alternating magnetic
field, the traction exerted by the jacket accelerates layer
breakup, drawing the particle bound drug or radionuclide against
and into the diseased tissue. When the ferrous matter in the jacket
is also heated, the combination of tissue warming and magnetic
attraction will usually further enhance local uptake of the drug or
drugs released. Particles, microspheres, and miniballs in tissue or
suspended in the lumen, and impasse-jackets themselves, can be
heated to release coatings and contents, or to apply magnetic
hyperthermia. The jacket outside the lumen wall, the effect does
not apply to thermoablation.
[1364] The temperatures involved in heating thus fall well below
the Curie temperature that would demagnetize the jacket. An
absorbable stent-jacket of polylactic coglycolic acid can
incorporate magnetized iron particulate that will provide the
magnetic force and when noninvasively heated by placing the patient
in a radiofrequency alternating magnetic field, will be heated to
melt a coating on the particulate that will enzymatically or
hydrolytically effect the breakdown or accelerate the dissipation
of of the jacket or other absorbable components when extraluminal
where the spontaneous rate of dissolution is usually less. In
nonabsorbable jackets, embedment thus can be used for hyperthermia,
to initiate or accelerate the release of a drug or its rate of
uptake, or to heat drug carrier nanoparticles once drawn into the
lumen wall whether as hyperthermia, to initiate or increase the
rate of drug uptake, or to dissipate or, or any of these purposes
in combination, for example.
[1365] The same pertains to other implants such as stays and
miniballs where it can be used to flow a bonding agent such as a
eutectic protein solder or release a drug as well as accelerate its
uptake, and miniballs whether ductus-intramurally implanted or
suspended in an impasse-jacket. Where ductus-intramural layer and
or melting point distinct dissolution is temperature controlled,
ductus-intramural miniballs and stays and endoluminal miniballs can
be used in coordination for timed delivery of different drugs or
combinations of drugs, those successive combining with,
supplementing, reversing, or counteracting such as by breaking down
to inactivate or neutralize, those released previously, as
addressed below in the section entitled Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays.
[1366] The system described herein allows temperature control
through multiple means, to include `cooling` catheters, which are
equally usable to raise the temperature in a barrel-tube, addressed
below in the sections entitled Rapid Cooling Catheter and Cooling
Capillary Catheter for Cooling Heated Turret-motor, Electrically
Operated Radial Projection Unit Lifting Thermal Expansion Wires and
Heaters, and Recovery Magnets and Cooling Catheters
(Temperature-Changing Service-catheters), among others, and inmate
heat-windows, addressed below in the section entitled Thermal
Conduction Windows (Heat-windows) and Insulation of the Muzzle-head
Body in Minimally or Fully Thermal Ablation and Thermal Ablation
and Angioplasty-capable (Independently Usable) Barrel-assemblies,
among others.
[1367] Although the miniballs, stays, stent-jackets,
impasse-jackets, and patch-magnets described herein are novel, that
these implants when containing ferrous matter or a resonant circuit
would be heated by placement in a magnetic field alternated at
radio frequency is uninventive. All of the magnetized implants
described herein, to include impasse-jackets, stent-jackets,
magnet-jackets, and patch-magnets support the magnetic drug and/or
radionuclide targeting of a length along a lumen or an entire
organ. With an endoluminal lesion, the drug is drawn against the
endothelium and directly into the lesion with or without the
addition of heat. For attraction against and into the lumen wall,
the drug, radionuclide, or other therapeutic agent is ferrobound,
that is, bound to magnetically susceptible carrier nanoparticles
and therefore drawn along with the susceptible carrier, which can,
for example, be contained in a ferrofluid or within the absorbable
envelope of a miniball that is dissolved by the introduction of
another substance and/or heat, for example.
[1368] When intended for release into the circulation, the
substance for targeted delivery is ferro co-bound, that is, not
indissolubly bound to magnetically susceptible particles, as this
would draw the substance against and into the lumen wall encircled
within the jacket. Instead, the delivering container, such as a
miniball or microspheres with an absorbable outer layer,
incorporate a magnetically susceptible core. The dissolution of the
outer layer that liberates the substance may be formulated to be
dissolved by the passing blood, with the subsequent, hence, time
controllable, administration of an agent that acts as a solvent, or
by heating at the level for release, such as by a heat-window or a
heat noninsulated tool-insert. Jacketing an artery that supplies an
organ, for example, allows the release of drugs, nutrients, or
other substances at the level of the jacket.
[1369] If the substance to be restricted to only the targeted
tissue is not taken up by it, that is, not assimilated, absorbed,
or catabolized within the parenchyma, then the outflow through the
jugular veins is jacketed when necessary to eliminate any unwanted
residue by releasing a drug molecule-cleaving, binding, inverse
agonist acting, or otherwise neutralizing or inactivating substance
(reversal agent). Impasse-jackets used to treat the brain are
solely for whole-brain treatment with one jacket releasing
medication from miniballs it holds at the inlet (internal carotid
artery) and when necessary, another jacket at the outlet (the
jugulars) to release a reversal agent, counteractant, or
neutralizing substance. Also, for incorporation into microspherules
or miniballs, the drugs must be capable of high concentration. The
uses of impasse-jackets is, then, fundamentally different in
application from those of percutaneous transluminal microcatheters,
which are passed up into a vessel within the brain to target a
glioblastoma with a large volume of a mannitol and after a few
minutes, an antiangiogenic drug, for example.
[1370] A stereotactic magnetic guidance system for the delivery of
drugs within the brain is based upon a separate technology (see,
for example, Abrishamkar, S., Moin, H., Safavi, M., Honarmand, A.,
Hajibabaie, M., Haghighi, E. K., and Abbasifard, S. 2011. "A New
System for Neuronavigation and Stereotactic Biopsy Pantograph
Stereotactic Localization and Guidance System," Journal of Surgical
Technique and Case Report 3(2):87-90; Leach, J. H. 2003. Magnetic
Targeted Drug Delivery, Masters Thesis, Virginia Polytechnic
Institute and State Universiry, Blacksburg, Va.; McNeil, R. G.,
Ritter, R. C., Wang, B., Lawson, M. A., Gillies, G. T., Wika, K.
G., Quate, E. G., Howard, M. A., III, and Grady, M. S. 1995.
"Functional Design Features and Initial Performance Characteristics
of a Magnetic-Implant Guidance System for Stereotactic
Neurosurgery," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Engineering 42(8):793-801; McNeil, R.
G., Ritter, R. C., Wang, B., Lawson, M. A., Gillies, G. T., Wika,
K. G., Quate, E. G., Howard, M. A., III, and Grady, M. S. 1995.
"Characteristics of an Improved Magnetic-implant Guidance System,"
Institute of Electrical and Electronics Engineers Transactions on
Biomedical Engineering 42(8):802-808). If implemented, the helmet
based system would be limited to the administration of drugs in the
clinic.
[1371] Once an impasse-jacket has been implanted, a drug can be
released directly into the bloodstream noninvasively with a quicker
response time obtained by collateral intramuscular injection. A
patient could, for example, trigger the release of an
anticonvulsant by warming the implantation site with an electrical
heater or by self injection. The prepositioning of different drugs
using such means is intended toallow targeted, quicker, finer, and
tighter control over the release of drugs, usually on a small
scale, than can be achieved through intramuscular injection. Tiny
patch-magnets used to hold miniballs of which the contents can be
released by heating or by exposure to another chemical, for
example, can be inserted within a parenchyma during open surgery
when the organ has been exposed if not entered for a primary
procedure.
[1372] A drug-binding ferrofluid released upsteam into the
circulation, whether by intravenous infusion, injection, or
ingestion, or microspheres or miniballs suspended within entry
impasse-jackets placed about the internal carotid arteries, for
example, will upon dissolution release drugs into the bloodstream.
If the outflow from the brain contains any of the drug but the drug
is neutralized, this substantially isolates and targets the brain,
the reduction in exposure of other head and neck structures to the
medication dependent upon the proximity to the brain along the
common then internal carotid artery. Limitation of delivery to the
brain will not avert psychological or hormonal side-effects that
also originate within the brain; however, avoiding the systemic
circulation substantially eliminates brain-unrelated side effects,
as well as allows the overall dose to be significantly reduced.
Isolation of the brain contemplates the use of antineoplastic,
germicidal, and antiparasitic drugs.
[1373] Thus, most of the adverse side effects associated with
antipsychotic or neuroleptic drugs, such as tardive dyskinesia,
weight gain, and akathisia, originate in or involve the brain;
however, non-brain-derived side effects such as agranulocytosis may
be avoidable if the systemic circulation is avoided. Other organs
can be isolated in an analogous manner. Closer approximation to the
brain along the internal carotid artery increases the dissection
needed to place the jacket. However, less proximate placement, even
though it less minimizes delivery to the non-brain parts of the
head and neck, avoids the greater trauma of more proximate
placement and still allows a signficant reduction in overall dose
compared to that required for delivery through the systemic
circulation. Release of the drug from an entry jacket must be
justified on this basis.
[1374] Whether released into the systemic circulation or at the
inlet to the brain, the drug must then be drawn into the brain.
Magnetic means alone will not overcome the blood-brain and blood
cerebrospinal fluid barriers, although in some instances, such
means can be adapted to accelerate the uptake of a drug carrier
substance such as nanoparticle-bound leukotriene C4 to temporarily
disrupt the barrier and/or a drug formulated to pass the barrier.
When no brain tissue has been removed, patch- or clasp-magnets are
placed in a sulcus (fissure, anfractuosity) between gyri or in a
subarachnoid cistern. In situations where tissue has been resected
or there is sufficient atrophy, intracranial (endoencephalic) space
will already have been created.
[1375] The feasibility of using an intracranial implant for
infusing medication directly into the brain, referred to as
intracranial or subarachnoid pharmacotherapy, goes back two decades
(see, for example, Smith, D. C., Krahl, S. E., Browning, R. A., and
Barea, E. J. 1993, "Rapid Cessation of Focally Induced Generalized
Seizures in Rats through Microinfusion of Lidocaine Hydrochloride
into the Focus," Epilepsia 34(1):43-53). However, compared to the
impasse-jackets and patch-magnets described herein, the apparatus
used was massive (see, for example, Fischell, R. E. Fischell, D. R.
and Upton, A. R. M. 2000. "Responsive Implantable System for the
Treatment of Neurological Disorders," U.S. Pat. No. 6,134,474;
Ludvig, N. and Kovacs, L. 2002. "Hybrid Neuroprosthesis for the
Treatment of Brain Disorders," U.S. Pat. No. 6,497,699; Ludvig, N.
2010. "Subarachnoid Pharmacotherapy for Maximizing Recovery after
Cortical Ischemic Stroke," Journal of Experimental Stroke and
Translational Medicine 3(2): 13-21; Ludvig, N., Medveczky, G.,
French, J. A., Carlson, C., Devinsky, O, and Kuzniecky, R. I. 2010.
"Evolution and Prospects for Intracranial Pharmacotherapy for
Refractory Epilepsies: The Subdural Hybrid Neuroprosthesis,"
Epilepsy Research and Treatment Hindawi Publishing 2010:1-11; Kahn,
A. R., Chow, E. Y., Abdel-Latief, O., and Irazoqui, P. P. 2010.
"Low-power, High Data Rate Transceiver System for Implantable
Prostheses," International Journal of Telemedicine and Applications
2010:563903).
[1376] Drugs to pass through the barrier can be bound to a glucose
or amino acid carrier or a large lipophilic moiety, for example,
(see, for example, de Boer, A. G. and Gaillard, P. J. 2007.
"Strategies to Improve Drug Delivery across the Blood-brain
Barrier," Clinical Pharmacokinetics 46(7):553-576; Nestler, E. J.,
Hyman, S. E., and Malenka, R. C. 2001. Molecular Neuropharmacology:
A Foundation for Clinical Neuroscience, New York, N.Y.:
McGraw-Hill, pages 29-32; Pardridge, W. M. 1998. "CNS Drug Design
Based on Principles of Blood-Brain Barrier Transport" Journal of
Neurochemistry 70(5):1781-1782).
[1377] That passage through the barrier of a magnetically
susceptible drug carrier nanoparticle-bound lipophilic molecule,
such as nitorosoureas or procarbazine (Fetell, M. R., 1995.
"Gliomas," in Rowland, M. P. (ed.), Merritt's Textbook of
Neurology, Media, Pa.: Williams and Wilkins, pages 341-342) would
be accelerated without the aid of adjuvant nitric oxide-generating
compounds, leukotriene C4, cyclic guanosine monophosphate-specific
phossphodiesterase 5 inhibitors through the oral administration of
sildenafil or vardenafil (see, for example, Black, K. L., Yin, D.,
Ong, J. M., Hu, J., Konda, B. M., and 7 others 2008. "PDE5
Inhibitors Enhance Tumor Permeability and Efficacy of Chemotherapy
in a Rat Brain Tumor Model," Brain Research 1230:290-302) or
bradykinin, and/or calcium-activation of potassium channels with
metastatic brain tumors (see, for example, (see, for example, Hu,
J., Yuan, X., Ko, M. K., Yin., D., Sacapano, M. R., and 7 others
2007. "Calcium-activated Potassium Channels Mediated Blood-brain
Tumor Barrier Opening in a Rat Metastatic Brain Tumor Model,"
Molecular Cancer March 14; 6:22), for example, is not
suggested.
[1378] The use of prepositioned precursory drugs (see, for example,
Rautio, J., Laine, K., Gynther, M., and Savolainen, J. 2008.
"Prodrug Approaches for CNS Delivery," American Association of
Pharmaceutical Scientists Journal10(1):92-102), is addressed below
in the section entitled Chemical Control over Implants and Coated
Implants, to Include Miniballs, Stays, and Prongs. When uptake is
incomplete as to leave a residue best prevented from entry into the
systemic circulation, drug carrier nanoparticles or microspheres or
miniballs containing these, for example, suspended within exit
impasse-jackets placed about the jugular veins proximate to the
outflow from the brain can be used to chemically and/or thermally
neutralize the residue, such as by binding with or cleaving the
drug or drugs.
[1379] By reducing the accumulation of drug carrier nanospheres in
neighboring nontargeted, healthy or less severely diseased tissue,
the use of small magnetized implants should also increase the
efficacy as well as the sufficiency of treatment (see, for example,
Pathan, S. A., Iqbal, Z., Zaidi, S. M, Talegaonkar, S., and 7
others 2009. "CNS Drug Delivery Systems: Novel Approaches," Recent
Patents on Drug Delivery and Formulation 3(1):71-89; Silva, G. A.
2008. "Nanotechnology Approaches to Crossing the Blood-brain
Barrier and Drug Delivery to the CNS," BioMed Central Neuroscience
10;9 Supplement 3:S4; Brigger, I., Morizet, J., Aubert, G., Chacun,
H., Terrier-Lacombe, M. J., Couvreur, P., and Vassal, G. 2002.
"Poly(ethylene Glycol)-coated Hexadecylcyanoacrylate Nanospheres
Display a Combined Effect for Brain Tumor Targeting," Journal of
Pharmacology and Experimental Therapeutics 303 (3): 928-936).
[1380] Even without complete absorption or catabolic breakdown by
the target tissue or organ, or neutralization of an outflow
residue, the dose, generally tiny compared to the equivalent
systemic dose even when much more highly concentrated for the
target segment or organ, once entering the systemic circulation is
quickly diluted to an innocuous level. Thus, when the agent used
has no neutralizing substance and is resistant to heat, dilution by
release into the systemic circulation can almost always be relied
upon without the use of an exit-jacket. Such means are capable of
targeting medication in a more focused manner than can an
intrathecal pump. Moreover, administration is without the internal
storage, potential for mechanical malfunctioning, and medical
complications associated with a pump implant. Similarly, using a
jacket on the renal artery and another on the renal vein, a kidney
can be selectively targeted to the substantial exclusion of the
systemic circulation. Keeping furosemide from reaching the cochleae
nullifies its potential as an ototoxin, the number of potential
examples myriad.
[1381] The need for a magnetic drug carrier attracting clasp or
patch-magnet on the organ fibrosa or the equivalent between the
entry, and if necessary, an exit-jacket, exists when the pathology
itself does not result in a reduction in the level of resistance to
penetration by and uptake of the drug. For example, while the
blood-brain barrier appears to prevent oncolytic drugs such as
paclitaxel from reaching therapeutic levels in normal brain tissue,
therapeutic levels are achieved with gliomas (Shen, Y., Pi, Z.,
Yan, F., Yeh, C. K., Zeng, X., and 5 others 2017. "Enhanced
Delivery of Paclitaxel Liposomes Using Focused Ultrasound with
Microbubbles for Treating Nude Mice Bearing Intracranial
Glioblastoma Xenografts," International Journal of Nanomedicine
12:5613-5629; Heimans, J. J., Vermorken, J. B., Wolbers, J. G.,
Eeltink, C. M., Meijer, O. W., Taphoorn, M. J., and Beijnen, J. H.
1994. "Paclitaxel (Taxol) Concentrations in Brain Tumor Tissue,"
Annals of Oncology 5(10):951-953).
[1382] Where tumor uptake is less, pressure within the tumor and
its effect on blood flow phenomena may limit penetration (Stewart,
D. J. 1994. "A Critique of the Role of the Blood-brain Barrier in
the Chemotherapy of Human Brain Tumors," Journal of Neurooncology
20(2):121-139). Restricted perfusion can to an extent be
compensated for by increasing the strength of magnetization of the
patch-magnet or magnets. Entry or inflow, and if necessary, exit or
outflow jackets, can thus be used to concentrate a taxane, for
example, in the brain while substantially sparing the rest of the
body from exposure to such an antimitotic drug. A mitosis inhibitor
or antimitotic suppresses cell division, and thus the division of
tumor and intimal hyperlastic cells, but also other cells with a
higher turnover rate, producing adverse side effects.
[1383] The high rate of cell division in hair follicles, for
example, results in the alopecia or hair loss seen during
chemotherapy with vinblastine, paclitaxel, and docetaxel, for
example (The Merck Manual of Diagnosis and Therapy, 18th edition,
Table 149-2). Significantly reducing if not eliminating the amount
of drug that reaches the hair follicles should eliminate this side
effect along with others of like cause. Contrariwise, drugs best
prevented from entering the brain include ifosfamid, fludarabine
phosphate, cisplatin, and nitrosourea carmustine, for example
(Fetell, M. R. and Balmaceda, C. M. 1995. "Complication of Cancer
Chemotherapy," in Rowland, M. P. (ed.), Merritt's Textbook of
Neurology, Media, Pa.: Williams and Wilkins, page 984).
[1384] Thus, by using a higher concentration than could be used
systemically and substantially restricting the release of the drug
to the brain by placing the entry impasse-jackets on the internal
carotids and releasing magnetic drug carrier bound medication from
encapsulated microspheres seized from the passing blood, the
neutropenia, anemia, myelosuppression, neutrotoxicity, peripheral
neuropathy presenting as numbness of the skin on the hands and
feet, paresthesia, bradycardia, and rarely, heartblock, which can
be induced by paclitaxel; the fatigue, nausea, and rash sometimes
induced by gemcitabine; and the constipation, nausea, diarrhea,
myelosuppression, neuropathy, dizziness, hypersensitivity reactions
in the form of bronchospasm, dyspnea, and hypotensionfluid
retention, rash, and stomatitis associated with docetaxal
(Sauseville, E. A. and Longo, D. L. 2005. "Principles of Cancer
Treatment: Surgery, Chemotherapy, and "Biologic Therapy," in
Kaspar, D. L, Braunwald, E., Fauci, A. S., Hauser, S. L., Longo, D.
L., and Jameson, J. L., Harrison's Principles of Internal Medicine,
16th Edition, New York, N.Y.: McGraw-Hill, page 477), for example,
if not eliminated, should be significantly reduced, along with the
hair loss and other possible side-effects of anticancer drugs.
[1385] That this means can be used to prevent drugs from reaching
the liver is especially significant for the reduction of adverse
side effects. Exit jackets are generally reserved for releasing
reversal agents or substances to neutralize or otherwise counteract
those released at the start of segment or organ inlet or inflow
when necessary. Such a substance may have been released to
accelerate the dissolution of a miniball or miniball coating in the
entry jacket when the use of heat was best avoided or may have been
used in combination with heat. Focused and able to deliver a higher
concentration of a drug, targeting remains applicable despite
metastasis, in which case, impasse-jackets and/or clasp-magnets are
applied to the other sites, and a collateral systemic dose
administered to restrain further spread of the disease. When
impasse-jackets are spaced at intervals along a ductus, the drug is
preferably introduced upsteam of each impasse-jacket rather than
upstream of the entire array.
[1386] Alternatively, injection or infusion upstream of the array
or a subset of jackets for auto-apportionment requires that the
drug carrier magnetic susceptibility, density of these, and the
tractive force of each jacket allow the blood pressure to drive
some microspheres or miniballs forward to the next impasse-jacket.
To this end, different fractions of the injectant can be made to
differ in magnetic susceptibility, and/or successive jackets can be
made to exert a stronger magnetic field than that preceding. A rate
of microsphere or miniball delivery that could clog a jacket for
more than a moment before the pulse force the miniball forward is
avoided. Since until metabolized, drugs magnetically held within
the targeted tissue will remain, and any residue that passes
through the target segment or organ would be immediately diluted,
an exit impasse-jacket to release a neutralizing substance is often
unnecessary.
[1387] Applicable no less to a delimited segment of a ductus or its
luminal endothelium than to an organ, targeting allows the use of a
drug to treat plaque, a tumor, or other lesion, and at a
concentration that if circulated would be toxic. In all
applications, the release of drugs and/or radiation from layered
miniballs using differential temperature and magnetic targeting can
be used. As addressed below in the section entitled Miniature Ball
Implants, an alternating magnetic field can be used to achieve
extracorporeal noninvasive control on a time-coordinated basis.
Release at the inflow jacket can be through spontaneous or time
released dissolution into the passing blood, or the drug can be
formulated to dissolve in a controllable manner in response to the
addition of a second drug, a nondrug chemical agent, and/or heat.
These possibilities make possible follow-up treatment at any time
over the period that the original miniball persists.
[1388] After that, continued treatment requires the infusion or
injection of another miniball, whether one of like or of different
formulation. That release can be triggered over a variable interval
allows prepositioning for scheduled dosing over an indefinite
period or emergency use. Release or accelerated release and uptake
through placement of the patient in an alternating magnetic field
to remotely heat the miniballs ties the patient to the clinic, but
another chemical administered orally as preferred or by injection
or infusion through a subcutaneously implanted portal to effect
dissolution of the trapped miniball does not. Impasse-jackets and
other magnetized implants are described and their applications
delineated; however, the potential number of combinations and
permutations of drugs, release or triggering mechanisms at both
inflow or entry and outflow or exit jackets, and the anatomical
structures to which these apply is potentially limitless so as not
to be ennumerable herein.
13. Concept of the Magnet-Wrap
[1389] A magnet-jacket, or magnet-wrap, comprises an array of small
permanent magnets mounted on a spandex backing with hook and loop
fasteners for wrapping about the ductus. It is usually intended to
optimize the radially outward directed attractive force over a
relatively large distance. It can be used to pull another ductus
toward it or to pull the ductus it encircles toward the attracting
magnet-wrap, patch-magnet, or simple magnetized and coated tab
inserted under the outer layer of other tissue. Applied thus, a
magnet-wrap, like a patch-magnet, must exert tractive force over a
greater distance than must a stent-jacket placed in close proximity
to the miniballs or stays it is to draw. A magnet-wrap is different
than a stent-jacket in that the stretchable backing provided to
allow longitudinal and circumferential compliance with motility in
the substrate ductus supplants a more rigid backing as is necessary
to draw ductus-intramural implants toward it, urging the ductus
into luminal patency.
[1390] Stretchability also requires the use of discrete magnets, as
defined above in the section entitled Types of Stent-jacket. In
general, a magnet-wrap or patch-magnet is more strongly magnetized
than is a stent-jacket. That either or both the structure attracted
and attracting can be magnetized is obvious. That if to be drawn to
a side or diverted in response to force imposed by a magnet or
magnets over a distance the jacket need not incorporate magnets but
only magnetically susceptible material is obvious. The radially
inward directed poles of the magnets can also be used to attract
underlying ductus-intramural implants or drug carrier
nanoparticles, but such use is extraordinary, just as is the use of
a stent-jacket for its outward directed poles.
[1391] Just as the contradictory distinctions in function that
distinguish stent- from impasse-jackets makes the attempt to
consolidate these into a single form inadvisable by degrading
performance in both functions, attempting to mechanically optimize
the form of an encircling sleeve for optimal use of both its inward
and outward directed poles yields a device suboptimal for both. A
stent-jacket can be used as a magnet mount to divert the vessel it
encircles or to draw other tissue radially inward or adaxially
toward it, and a magnet-wrap to attract in the radially outward or
abaxial direction. Magnet-wraps used to attract the clasps of a
clasp-wrap or miniballs over a distance may be strongly magnetized
and used for large ductus where extraction will not be necessary.
As is generally true of the components described herein, either the
miniballs or the jacket can represent the magnetized or the
susceptible factor. In the digestive or the urinary tract, the
release of a magnetized miniball or miniballs from a ferromagnetic
jacket through demagnetization would result in its spontaneous
elimination.
[1392] However, while the temperature required could be reached by
placing the patient in a radiofrequency alternating magnetic field,
for example, the demagnetizing or Curie temperature will be too
high for use inside the body, no material, much less one
functionally compatible with the need for absorption or elution,
for example, available that would insulate a core heated to 590
degrees Fahrenheit. When usable for this auxiliary purpose as well,
stays, which have a conformation better suited to sustaining a
magnetic circuit of high flux density than miniballs, will usually
be needed. The ductus wall must be confirmed as able to support the
increased tractive force involved. However, more reliable function
in the radially outward or adaxial direction (which uses the
abaxially facing pole) is obtained with a magnet-wrap
(magnet-jacket, magnet-collar, magnet-sleeve, magnet-cuff,
magnet-mantle, magnet-wrap-surround, magnet-bandage).
[1393] In contrast to stent- and impasse-jackets, a magnet-wrap
uses the outward facing or abaxial poles of discrete magnets to
exert tractive force in the radially inward (adaxial, axipetal,
centripetal) direction. This force is applied to ferromagnetic
implants infixed within another structure, discrete magnets
providing the mass necessary to act over a distance. Unlike jackets
for optimizing application of the inward looking poles to treat the
substrate ductus itself, a magnet-wrap is unslit, without resilient
backing, and almost never magnetized over more than a restricted
arc about its circumference. It uses the substrate or encircled
(ensheathed, mantled, enwrapped) ductus as but a mounting platform,
itself not ordinarily under treatment.
[1394] The adaxial poles of themagnets can of course be used as
well, to attract a drug carrier particulate, for example, but
abaxial force is more uniformly applied by a stent- or
impasse-jacket. The tissue drawn may be that of another ductus
implanted with miniballs or stays or encircled by a clasp-wrap,
described below in the section of like title, or nonductal tissue
implanted with magnetically susceptible matter, which can consist
of as a simple iron tab with or without a chemically isolating
coating infixed within it. Since an affected ductus would normally
be treated with a stent-jacket, and a stent-jacket can be used to
exert ductus wall retractive force entirely about the circumference
or over any arc desired, a magnet-wrap is used either to deflect
either the platform or drawn ductus from its course or to draw
nonductal tissue.
[1395] For example, within the constraint imposed upon the amount
of force that may be used by the need to avert dysphagia, a
magnet-wrap might be used to encircle the esophagus, thereby to
exert patenting force on the trachea when collapsed or stenosed.
Here it is ordinarily the roof or dorsal ligament (dorsal membrane)
of the trachea that drops down into and obstructs the airway
because the cartilage `rings` have lost or not gained the strength
required to support it, so that retractive or lifting force between
apposite, or juxtaposed, sides of the two ductus would clear the
airway. The stent-jacket can retract any arc about a ductus wall or
draw it outwards circumferentially, and concentric, is closest,
allowing the local use of the smallest possible ferromagnetic
elements.
[1396] However, in some situations, alternative means for the
support of the magnets will be necessary, specifically, for
example, when traction that entirely surrounds the vessel or duct
to be treated is not necessary and embedment within the surrounding
tissue, attachment, or adhesions preferred left in place
necessitates excessive dissection for the ductus to be approached
and encircled. Such a ductus can be implanted with miniballs
transluminally, and drawn from without by means of a magnet-wrap,
clasp-magnet, or a simple tab magnet implant. In other use, the
ductus, other tissue, either the substrate ductus or the structure
drawn may have developed or become deviated, displacing or
encroaching upon other tissue where the passage of magnetic lines
of force through intervening tissue achieves the same retraction or
fixation as would surgery but with less trauma, suture incapable of
direct traction thus.
[1397] When, for example, the presence of an intervening structure
precludes fixation with suture in the direction preferred, placing
a clasp-wrap, ductus-intramual implants (miniballs or stays) or
introducing ferromagnetic suture (see, for example, Slatter, D. H.
2002. Textbook of Small Animal Surgery, Oxford, England: Elsevier
Health Sciences/Saunders, page 146) or staples, for example, allows
the use of a magnet-wrap or clasp-magnets to retract the tissue
instead. A collapsed ductus secured by connective tissue along one
side as not to require retraction in that direction requires
tractive force that is arcuate or directed rather than
circumvascular. For example, having longitudinal muscle and diffuse
connective tissue peripherally rather than a harder outer layer,
the esophagus, as can be true of any diseased malacotic vessel,
does not lend itself to implantation.
[1398] Nevertheless, a magnet-wrap can be used, for example, to
suspend miniballs implanted along dorsolateral lines of the
collapsed trachea in a toy breed dog from ventrolateral magnets
along complementary parallel lines of magnets held within a
magnet-jacket or jackets wrapped around the esophagus. Eccentric
lesions in the vasculature are generally not anchored along one
side so that tugging at a vessel would, arising concern for the
affect on hydrodynamic blood flow through the ductus, its
endothelial or vasotonic function, as well as compression on tissue
bounding the side pulled. With other ductus, the concern will be
the possibility of disrupting peristalsis. If not sufficiently
immobile, the mounting platform looked to for positional stability
may require some sutures or a more powerful permanent magnet to
fixate. Then, depending which ductus is fixated, either the
magnet-wrapped ductus or that drawn by it can be aligned or
diverted.
[1399] Unless the field is already exposed for another surgical
procedure, a magnet-wrap, clasp-wrap, and stays are inserted by
laparoscopic entry. Such a less traumatic solution can be used to
defer surgery until the patient can tolerate it or as a palliative
measure for a patient with little time left. Traction exerted by a
magnet-wrap used thus will almost always apply in a
circumferentially limited (eccentric, radially asymmetrical) way as
not to require magnets or magnetized content entirely about the
circumference. Accordingly, adaxial or magnet-wraps differ from
abaxial stent- and impasse-jackets in having a nonslitted and less
resilient backing and far more often, exertion of magnetic force
that is circumscribed or arcuate rather than entirely about the
circumference. Magnet-wraps are addressed below in the section of
like title. Generally not anchored along one side, tugging at a
vessel with an eccentric lesion may affect hydrodynamic blood flow
through the vessel, its endothelial or vasotonic function, as well
as compress the tissue at the pulled side.
14. Concept of the Nonjacketing Side-Entry Connector
[1400] Ductus side-entry jackets about either or both internal
carotid arteries allow the directly pipe-targeted delivery to the
brain of any drug, whether psychotropic or oncolytic, for example,
to the brain, for example. Brain tumors commonly require treatment
with detumescent and anticonvulsant as well as chemotherapeutic
medication. The side-entry connector can deliver drugs or
electrostimulation with any pattern of stimulatory pulsation, such
as alternating electric field therapy through an electrode and/or
the semicircular needles used to anchor the connector. Once placed,
drug delivery and fluid aspiration are not through the scalp but
rather through the fluid lines connected to one or more subdermally
placed small drug reservoir pumps and/or electrical lines entered
through a small surface port addressed below.
[1401] More circumscribed targeting should seldom prove necessary,
but can be accomplished by trephination and attachment of a
nonjacketing side-entry connector directly to the surface of the
dura mater or the cortex itself. Aside from the automatic control
system with which a side-entry connector, unlike an Ommaya
reservoir, is compatible, the connector itself is more versatile,
in that it can deliver targeted molecular as well as well as
electrostimulatory, cautery, hormonal, nanoengineered enzyme,
and/or cytotoxic therapy. The catheter can be used as might an
Ommaya reservoir to aspirate or release drugs into intraventricular
cerebrospinal fluid, or the tip of the catheter, probe, cautery
device, electrode, laser, fiber optic endoscopic viewer, or other
miniature cabled device can be aimed at or inserted into a tumor
such as an astrocytoma or glioblastoma multiforme. Automatic
adaptive disorder response systems are addressed in sections XX.
and XXI. below.
[1402] Use thus of a nonjacketing side-entry connector is described
and illustrated in copending application Ser. No. 14/998,495, FIGS.
13A and 13B. As shown in FIGS. 14 thru 16 therein, any catheteric
or styloid device can be motorized to gradually pass into or
through the tumor. Bidirectional fluid lines for aspiration and
drug delivery and electrical lines are led from a small drug entry
port or, if no electrical lines are required, a conventional
portacath or mediport implanted subdermally in the pectoral region
to the connector beneath the dermis and scalp. When an electrical
socket and one or more button cell batteries are needed, a port of
the kind shown in copending application Ser. No. 14/121,365, FIGS.
27 and 28 is used.
[1403] Whether adjunctive to primary external beamed radiation, to
convey radioactive substances of small to moderate dose rates, the
nonjacketing connector can be radiation shielded as shown in FIGS.
10A and 10B of the same application. The connector thus allows
radiation as well as chemotherapy. For attachment to the cortex,
the semicircular anchoring needles can be replaced with prongs to
obtain positional stability with minimal penetration. As shown in
copending application Ser. No. 14/121,365, FIGS. 9 and 11, the
anchoring needles can be hollow to inject drugs into the substrate
tissue and/or electrified to deliver electrostimulation. If not
manual by injection into the subdermal port, the timing of drug
delivery through the main catheter or stylus and/or the anchoring
needles is governed by the prescription program executed by a
microprocessor, which controls the tiny outlet pumps of the drug
reservoirs to which the opening in the surface port are connected
by catheters.
[1404] When the surface port is used only for injection, the
openings are subdermal with tiny tattoos to indicate the injection
points. A surface port to house a battery and/or serve for
aspiration is mounted on the skin. The prescription program can
coordinate the automatic treatment local to the brain with that
systemic and/or involving other tissues or organs. This capability
is beneficial when a brain tumor, for example, has metastasized
from another part of the body, most often, a lung, which would
similarly be treated locally, as well as with circulated
chemotherapeutics and external beam therapy, and so on, to truncate
further metastasis. Such an automatic disorder response system can
administer drugs locally and systemically to treat comorbid
conditions whether malignant or benign in a coordinated manner as
to best maintain homeostasis. This capability expands upon
conventional means for targeting nidi or lesions and functions
independently of the ability of the patient to adhere to a
treatment regimen, especially one complicated as comorbidity
demands.
15. System Requirements
[1405] The essential system requirements are best set forth in
terms of use in the vasculature as presenting that environment most
demanding. Use in the respiratory, gastrointestinal, urinary, and
genital tracts will encompass a subset of features, and use to
introduce implants into tissue not lining a ductus will dispense
with most of these requirements. In arteries, especially the
coronaries and the internal carotids, the essential requirements
for the apparatus and methods include minimizing the risk of a
midprocedural crisis due to perforations, dissections, or ischemia
due to obstruction of the lumen, whether the result of occlusion by
the apparatus itself, an abrupt closure, thrombus, thromboembolism,
gas embolism, swelling, and/or vasospasm whether the result of
aeroballistic implantation. An angioplasty-capable barrel-assembly
must be capable of performing an angioplasty by different means, to
include cutting, shaving, abrasion by brushing or scraping
(curettage, evidement), and those thermoplastic, radiofrequency and
laser methods optional.
[1406] In veins, minimizing the potential for protracted
obstruction, to include blockage by the apparatus, thrombus,
embolism, and gas embolism is imperative. Embolism includes that
intrinsic (thromboembolitic or coagulative), that due to a release
of debris from a ruptured plaque, that due to intravasation or
accidental entry of a miniball into the bloodstream, and the
foregoing in any combination. Thromobogenicity is reduced by
minimizing or eliminating metal surfaces in contact with the blood,
avoiding thrombogenic operating temperatures, preventing blood from
entering and clotting in the openings of the muzzle-head, and the
use as necessary of adjuvant medication, such as a platelet
blockade, nitrates, and/or an anticoagulant. To reduce the risk of
perforations and dissections, the muzzle-head must be free of any
protrusions, present a blunt-ended torpedo nose and rounded contour
over the trailing shell. The muzzle-head must and slippery and not
seize, pull, gouge, or cling to the endothelium.
[1407] Intravasated miniballs must be instantly arrested and
recovered, and mispositioned or embolizing miniballs must be
immediately recoverable. To allow precise aiming in the
structurally differentiated tracheal lumen, an easily viewed
singular exit-port at the distal end is essential. Such a simple
pipe type muzzle-head is without the torpedo-shaped shell or
envelope needed for transluminal movement within a smaller and
structurally undifferentiated ductus such as a blood vessel or
ureter. Except for use in the airway, the muzzle-head is contained
within a torpedo shaped shell and can be made capable of delivering
multiple implants per discharge. Pull-through denoting the gradual
penetration and eventual perforation through the tunica adventitia
or fibrosa of a miniball under the sustained magnetic traction
needed to retract a stenosed lumen wall and/or to attract a
magnetic drug-carrier from the passing contents of the lumen
(usually blood), the forces involved in airgun discharge and
magnetic traction must be minimized to prevent perforations during
and pull-through following discharge.
[1408] To this end, the system must be capable of placing miniballs
ductus-intramurally at close and uniformly spaced intervals as will
evenly distribute rather than concentrate the tractive force on any
one or a few. Such precise placement cannot be achieved under
manual control, much less at a rate to minimize procedural time. To
overcome this limitation necessitates the application of a
positional control system. The apparatus must make possible the use
of tissue bonding agents to overcome delamination in the form of
inter- or intratunical separation and pull-through, both of which
would result in stent failure. An ablation-capable barrel-assembly
must be capable of ablating hyperplastic or neoplastic tissue and
accreted matter obstructive of the lumen by those means stated for
an angioplasty-capable barrel-assembly. The barrel-assembly must be
sufficiently flexible to track and steer without winding or
twisting when torqued.
[1409] To optimize the reach of a muzzle-head of given size down a
narrowing ductus, the miniball discharge exit-port or ports
(exit-holes) must be placed as far distad (forward) as the
incorporation of recovery electromagnets will allow. Almost all
muzzle-heads will also incorporate a front end heat-window, and
many, a fiberoptic endoscope, angioscope, laser photoablater,
and/or an embolic filter stowed in the part of the muzzle-head
forward of the exit-port or ports, or the nose. Extraluminal stents
must comply with angiotensive adjustments in caliber of the
encircled vessel and with expansion and contraction in the
encircled ductus, whether peristaltic, tonic, or pulsatile.
Intrinsically magnetized stent-jackets must exert sufficient
tractive force on the miniball or stay implants to maintain luminal
patency while remaining thin enough to comply with expansion and
contraction in the substrate ductus.
[1410] Polymeric stent-jacket base-tubes must resist chemical
breakdown and not lose pliancy in the internal environment as to
necessitate revision (replacement) at intervals of less than
several years. A moisture barrier-coated viscoelastic polyurethane
foam lining is essential to provide the encircled ductus with
clearance for the passage of small nerves and vessels into and out
of the adventitia. The stent-jacket lining must impose no more than
negligible and adaptable pressure against this perivascular
microvasculature, or vasa vasora, and nervelets, or nervi vasora.
An expansion insert is necessary to allow adjustment to a reduction
in swelling over time. All of the materials used must be bioinert,
sterilizable, or disposable, and capable of remaining implanted
over a period of years. The essential design of a type
barrel-assembly should be capable of enlargement or miniaturization
without significant degradation in performance.
[1411] Means must be provided for testing the penetration and
puncture resistance of the actual tissue to be implanted with
miniballs. This information will assist to determine whether
miniballs can be used, and if so, the setting for the airgun exit
velocity. Stays are essential for tissue that is too malacotic to
retain miniballs. Testing must be provided to gauge the resistance
to delamination and pull-through of the actual tissue to be
implanted with stays. This will determine whether stays can be
used, if so, how wide the stays should be, and whether coating the
stays with a tissue bonding agent is necessary to prevent tunical
delamination. Mispositioned stays must be instantly recoverable.
The stay insertion tool must minimally interfere with the use of
imaging equipment to confirm the substantial concentricity of
ductus-intramural insertion. Interventional airguns must be capable
of quickly repeating discharge (or `firing` rate) without deviation
in exit velocity. Except where the type of miniballs used is to be
changed, the need for reloading should be minimized.
16. System Features
[1412] The capabilities imparted by the system apparatus and
methods exceed these requirements. For use in a structured lumen or
to target an organ, the barrel-assembly has the form of a pipe
which is usually curved toward the distal end. The pipe is in
effect a singular barrel-tube, the portion of the pipe distal to
the curve representing the muzzle-head and its open distal tip the
exit-port. For use in a generally small-diameter undiffentiated
lumen wherein one or more miniballs can be released with each
discharge, the barrel-tube or tubes are enclosed within a
protective shell having a rounded torpedo contour that serves to
reduce the risk of perforations or incisions. Gas is prevented from
entering the bloodstream during discharge by equalizing differences
in internal pressure, which is maintained to prevent the inflow of
blood into the exit-ports (exit-holes) and airgun gas pressure
relief channels where it would coagulate to form clots and affect
performance.
[1413] The use of a muzzle-head inmate turret-motor allows rotation
without torquing, hence, sufficient flexibility for tracking and
steering. The barrel-assembly can be used to target lesions for the
delivery of miniballs containing any medication and/or numerous
other therapeutic substances which may or may not relate to
stenting, thus eliminating the dilution and risk of side-effects of
a larger and more costly dose injected or infused into the
circulation rather than targeted. Ablation or angioplasty-capable
barrel-assemblies can function independently to perform an ablation
or an angioplasty, and then be inserted into an airgun to deliver
miniballs without the need to withdraw and reenter. This factor not
only reduces procedural time but minimizes entry wound irritation
and the risk of hematoma and infection. Medication miniballs are
implanted into or adjacent to circumscribed lesions, tissue
strength pretesting used to determine the exit velocity needed for
placement at the desired depth.
[1414] Miniballs can be radioactive seeds, magnetized, and/or
release any therapeutic substance to include a magnetic drug
carrier-binding particles in a ferrofluid to be drawn into tissue
between the releasing and a magnetized stay or stays, miniball,
patch-magnet, of any combination of these. The ferrofluid can also
be administered by infusion, injection, or orally to treat one or
more circumscribed sites, which the implants can also be used to
warm. Stenting miniballs are placed subadventitially or
perimedially in ductus and subfibrosally in organs. When not
precluded by the structured anatomy of the lumen, procedural
duration is also reduced by discharging multiple miniballs
simultaneously. Mounting the airgun on a linear positioning stage
moved by a positional control system not only speeds up
implantation but makes possible a degree of transluminal precision
that is essential but unattainable with manual control, the
successive discharges implantable uniformly at millimetric
intervals.
[1415] An ablation or ablation and angioplasty-capable
barrel-assembly can be made as two complementary components, each
usable independently of one another or an airgun. Such a duplex
composite or bipartite barrel-assembly consists of a radial
discharge barrel-assembly and a size-matched combination-form
radial projection catheter with a central channel used to ensheath
the barrel-assembly. To change the tool-inserts midprocedurally
with relatively little irritation to the entry wound, the outer
sheath or radial projection catheter is withdrawn and reintroduced
using the stationary barrel-assembly as a guide. A slidable
ablation or ablation and angioplasty-capable barrel-assembly power
and control housing allows the quick addition to or removal from
the barrel-assembly of a combination-form radial projection
catheter and the ability to grasp the barrel-assembly at a
consistent distance from the introducer sheath while eliminating
joints in the barrel-tube or tubes. Providing each apparatus with
its own control panel significantly reduces the chances for human
error.
[1416] By omitting miniballs, an extraluminal stent can omit weaker
portions of the lumen wall from patenting traction. Attachments and
ostia can be accommodated. Radial projection units can accept
tool-inserts that eject any therapeutic substance into the lumen,
or inject any therapeutic substance into, heat, chill, ablate, or
abrade the lumen wall. Spring-released or electrical/fluid
system-neutral syringe radial projection unit tool-inserts allow
fluid medication or other therapeutic substances to be delivered
through electrically operated radial projection units whether the
radial projection units are in the barrel-assembly muzzle-head, in
an ensheathing combination-form radial projection catheter, or in a
separate radial projection catheter. The incorporation of direction
of flow-driven fluid resistors allows the same fluid-operated
tool-inserts to irrigate with water or a therapuetic fluid, deliver
a therapeutic fluid, or irrigate or aspirate intermittently or
continuously as necessary. Incorporating two or more fluid radial
projection circuits allows concurrent irrigation and
aspiration.
[1417] A fluid-operated tool-insert can be preloaded to deliver an
initial dose of medication and thereafter be used to irrigate with
water or a therapeutic fluid or deliver a therapeutic fluid,
irrigate or aspirate intermittently or continuously as necessary.
The muzzle-head can be furnished with spring-released or
electrical/fluid system-neutral syringe radial projection unit
tool-inserts which can be used to coat the lumen wall with a
lubricant. A lubricant can also be spread onto the lumen wall by
means of a piston plunger or elongated injection syringe type
service catheter having a membrane slit at its distal end. The
service catheter is inserted (run, snaked) through an unused
barrel-tube. Turret-motor functionality is optimized by using its
windings as heating elements and to oscillate the muzzle-head. The
lubricant can be used with the oscillatory modes of the
turret-motor to expedite passage through tortuous stretches. The
recovery electromagnet windings are also used as heating
elements.
[1418] The heating elements have multiple uses, to include
accelerating the setting of cements, the rate of drug uptake, and
thermoplasty (thermal angioplasty). The barrel-assembly itself
and/or the lumen into which it is inserted can also be heated or
chilled by attaching a nitrous oxide or carbon dioxide cartridge or
a vortex tube `cold` air gun connected to a tank of compressed air
to a socket on the side or proximal end of barrel-assumbly. In any
ductus, heat can be used for thermoablation and cold for
cryoablation. An ablation or angioplasty-capable barrel-assembly
can thus remove diseased tissue from the lumen by mechanical or
temperature means. The motion and temperature functions have
separate clearly marked controls, so that sending current to the
windings of the electromechanical actuators within the muzzle-head,
which are also used for positional control and implant recovery
respectively, does not promote operator errors. With identical
radial projection unit lifting mechanisms in a given electrical or
fluid circuit, variable lifting or projection force is relegated to
the radial projection unit tool-inserts.
[1419] Electrically operated ejection and injection tool-inserts
can warm their contents. Electrical tool-inserts can be hot plates,
and fluid operated tool-inserts can be hot or cold plates. Using a
turret-motor to rotate the muzzle-head allows the barrel-assembly
the flexibility needed for tracking and steering. The ability to
achieve oscillatory action is prompted by the fact that whereas
slower machine speeds tend to promote snagging with stretching and
incisions, high speeds and sharp cutting, shaving, or abrading tool
edges reduce the risk of trauma. An elastomeric flexible joint in
the muzzle-head enhances trackability and supports turret-motor
induced muzzle-head oscillation as programmed or through
intentional derivative gain overdrive through damping and
compliance. Rotation its only degree of freedom, oscillation of the
turret-motor supports radial projection tool-inserts having
circumferentially but not longitudinally oriented cutting edges or
working faces.
[1420] Unless driven by a linear motor eliminating the need to
convert to linear motion, the limitation to rotation also applies
to the linear stage motor, of which the rotation is fixedly
(structurally, kinematically) converted to longitudinal with high
stiffness, or little if any play. Transluminal or reciprocating
oscillation of tool-insert working faces or cutting edges is
therefore obtained by intentionally overdriving the linear
positioning stage motor regardless as to type as direct current
closed loop (nonstepping), stepper, or linear. When the motor and
stage are capable of achieving oscillatory frequencies in response
to control instructions, transluminal or reciprocating motion to
support tranluminally oriented cutting or abrasive action can be
obtained by incorporation into the instruction set or programming
To avert injury to the vasa and nervi vasora of arteries and the
equivalent fine structures about the outer tunic of other kinds of
ductus treated, the extraluminal component of the magnetic stent,
or stent-jacket, is lined with polyurethane moisture barrier-coated
viscoelastic polyurethane foam.
[1421] So that the caliber of the stent-jacket will change in pace
with the substrate ductus, stent-jackets can be provided with
expansion inserts that are absorbed or crushed on demand as
swelling or inflammation of the ductus subsides. The system
provides multiple implant recovery and `bailout` strategies, to
include recovery electromagnets in muzzle-heads and stay insertion
tools, impasse-jackets, and adaptation of an external
electromagnet. A combination-form barrel-assembly has a central
bore or channel for incorporating a cabled device such as a
rotational or directional atherectomy or a thrombectomy cutter or
an excimer laser. Such devices can be exchanged midprocedurally
without withdrawal or any one such device can be installed
permanently.
[1422] A radial discharge barrel-assembly with a built in
angioscope or fiberoptic endoscope or laser, for example, is
technically a combination-form, although the term pertains more to
use of the central channel interchangeably and mostly to
incorporate rotational tools such as atherectomizers and
thrombectomizers. Whether a given cabled device is installed
permanently or interchangeably with others depends upon the number
of its applications where switching to another cabled device
midprocedure is unnecessary. When the cabled devices are
permanently installed, one barrel-assembly must be withdrawn and
another inserted, which is not preferred. Cabled devices that can
be built into or interchanged in barrel-assemblies for
thermoangioplasty include those using radiofrequency, laser, and
ultrasound. Those using fulgurating (electrofulgurating,
electrodessicating) electrode based thermoablation are suitable for
use in nonvascular ductus such as to perform a bronchial
thermoplasty.
[1423] A radiofrequency thermoplasty probe can serve not only to
eliminate vulnerable plaque, but to reduce the degree of
restenosis, yield a larger lumen, and fuse ductus-intramural
delaminations and dissections, to include flaps that induce abrupt
closures. Microwave balloon angioplasty is likewise claimed to seal
arterial dissections (Landau, C., Currier, J. W., Haudenschild, C.
C., Minihan, A. C., Heymann, D., and Faxon, D. P. 1994. "Microwave
Balloon Angioplasty Effectively Seals Arterial Dissections in an
Atherosclerotic Rabbit Model," Journal of the American College of
Cardiology 23(7):1700-1707) and yield increased luminal diameter
(Nardone, D. T., Smith, D. L., Martinez-Hernandez, A., Consigny, P.
M., Kosman, Z., Rosen, A., and Walinsky, P. 1994. "Microwave
Thermal Balloon Angioplasty in the Atherosclerotic Rabbit,"
American Heart Journal 127(1): 198-203).
[1424] More specifically, with the lumen wall under low compression
(see, for example, Fram, D. B., Gillam, L. D., Aretz, T. A.,
Tangco, R. V., Mitchel, J. F., and 5 others named, et al. 1993.
"Low Pressure Radiofrequency Balloon Angioplasty: Evaluation in
Porcine Peripheral Arteries," Journal of the American College of
Cardiology 21(6):1512-1521) achieved through the use of an
oversized muzzle-head and preplaced stent-jacket, radiofrequency
thermoplasty fuses or welds tunics (see, for example, Kaplan, J.,
Barry, K. J., Connolly, R. J., Nardella, P. C., Hayes, L. L., Lee,
B. I., Waller, B. F., Becker, G. J., and Callow, A. D. 1993.
"Healing after Arterial Dilatation with Radiofrequency Thermal and
Nonthermal Balloon Angioplasty Systems," Journal of Investigative
Surgery 6(1):33-52; Becker, G. J., Lee, B. I., Waller, B. F.,
Barry, K. J., Kaplan, J., Connolly, R., Dreesen, R. G., and
Nardella, P. 1990. "Potential of Radio-frequency Balloon
Angioplasty: Weld Strengths, Dose-response Relationship, and
Correlative Histology," Radiology 174(3 Part 2):1003-1008; Lee, B.
I., Becker, G. J., Waller, B. F., Barry, K. J., Connolly, R. J.,
Kaplan, J., Shapiro, A. R., and Nardella, P. C. 1989. "Thermal
Compression and Molding of Atherosclerotic Vascular Tissue with Use
of Radiofrequency Energy: Implications for Radiofrequency Balloon
Angioplasty," Journal of the American College of Cardiology
13(5):1167-1175; Barry, K. J., Kaplan, J., Connolly, R. J.,
Nardella, P., Lee, B. I., Becker, G. J., Waller, B. F., and Callow,
A. D. 1989. "The Effect of Radiofrequency-generated Thermal Energy
on the Mechanical and Histologic Characteristics of the Arterial
Wall in Vivo: Implications for Radiofrequency Angioplasty,"
American Heart Journal 117(2):332-341) confirmed by imaging to have
delaminated, which condition left untreated precludes magnetic
extraluminal stenting.
[1425] Laser thermoplasty has been credited with these benefits as
well (see, for example, Cheong, W. F., Spears, J. R., and Welch, A.
J. 1991. "Laser Balloon Angioplasty," Critical Reviews in
Biomedical Engineering 19(2-3):113-146; Geschwind H. 1989. "Laser
Angioplasty," in French with English abstract at Pubmed, Annales de
cardiologie et d'angeiologie. (Paris, France) 38(8):445-448) as has
thermoplasty with the aid of an ultrasound probe (Rosenschein, U.
und Budde-Schwartzman, B. 1997. "Koronare Ultraschallangioplastie:
Standpunkt und neue klinische Aspekte," ("Ultrasound Coronary
Angioplasty: State of the Art and New Clinical Aspects"), in German
with English abstract at Pubmed, Herz (Heart) 22(6):308-317).
OBJECTS OF THE INVENTION
[1426] 1. A central object of the invention is to make possible the
targeting of medication, another therapeutic substance, and/or a
radioactive seed into any tissue, but especially into, adjacent to,
or past a lesion in the wall surrounding a lumen, thus avoiding
systemic dispersal with the indiscriminate exposure of other tissue
and the risk of side effects.
[1427] 2. Another object of the invention is to provide for
magnetic extraluminal stenting that eliminates the need to place a
foreign object within a diseased lumen, thus avoiding a chronic
irritant and scaffold for accumulating occlusive matter.
[1428] 3. Yet another object of the invention is to reduce the need
for a percutaneous transluminal reintervention or surgical
revascularization made necessary by the intimal hyperplasia that
follows luminal stretching by a balloon through the use of
alternative means for performing an angioplasty, which uninflated,
are less likely to cause incisions that result in an abrupt
closure.
[1429] 4. Another object of the invention is to provide
extraluminal stents and ductus-intramural implants that also allow
magnetic drug-targeting by exerting magnetic force to extract a
ferrofluid-bound drug from the passing blood, thus concentrating
the drug in the lesion encircled by the stent.
[1430] 5. Another object of the invention is to augment the
treatment options for the many conditions that stenose, weaken, or
collapse the different types of tubular anatomical structures.
[1431] 6. A further object of the invention is to provide a long
term if not permanent stent, which vasomotility compliant, can be
used preventively by extension to portions of the ductus expected
to necessitate treatment in the future.
[1432] 7. Yet another object of the invention is to provide a stent
that can adapt to changes in caliber of the treated ductus.
[1433] Further objects of the invention include the provision
of:
[1434] 8. Implantation by means of a special airgun of spherules,
or miniature balls, containing therapeutic ingredients whereby
penetration is so sudden that tissue trauma and implant
mispositioning are minimized, the entry punctures, no wider than
the implants, immediately sealing and quickly healing.
[1435] 9. Peradventitial rather than ballistic infixion of
ductus-intramural implants containing ferrous matter and
optionally, therapeutic substances, for release into the
surrounding tissue in the form of stays, which can be circumfugally
attracted to stent, and additionally used to attract
ferrofluid-bound drug carrier particles from the passing blood
while avoiding the lumen entirely.
[1436] 10. Implantation with repeatable control over the force of
impact, so that allowing for the variability in mechanical
properties of diseased tissue, a consistency in depth of
penetration can be achieved that to attempt to duplicate with a
hand tool would pose difficulty and prompt hesitancy likely to
result in increased injury.
[1437] 11. Simple in situ tissue testing and procedural means that
intuitive and empirical, eliminate complications such as the need
for computation, and are quickly accomplished pre- or
midprocedurally, thus minimizing the chances for human error.
[1438] 12. Apparatus that is intuitive and simple to use thereby
minimizing the chances for human error.
[1439] 13. Angioplasty catheters that do not use a balloon and can
be inserted into an airgun to initiate the discharge of miniballs
to implant and/or to draw and concentrate medication and/or to
serve as the ductus-intramural component of an extraluminal
magnetic stent immediately, without the need to withdraw and
introduce a second stent delivering balloon catheter, thus averting
luminal stretching as well as repeated passage through and
irritation to the entry wound.
[1440] 14. Angioplasty catheters which incorporate components that
allow atheroablation and can additionally incorporate a prior art
cabled device, such as a laser or rotational burr for removing
calcified plaque, rather than crushing plaque up against the lumen
wall, thus yielding an overall result more durable than that
obtained through prior art angioplasty and atherectomy.
[1441] 15. Systems and methods that adapt the stenting means
described herein for alleviating tracheal collapse in small dogs,
for example, thus averting the need for an open surgical procedure
that demands extensive dissection and poses jeopardy to the
tracheal vasculature and neurology at a time when the operative
risk is greatest and the trauma least tolerable.
[1442] 16. Further to alleviate collapsed trachea without the need
for a thoracotomy, a new form of stent that is placed through a
small incision to encircle the trachea, and thus not susceptible to
the accumulation of mucus that necessitates frequent reinspection,
withdrawal, and revision (replacement).
[1443] 17. Systems and methods that reduce or eliminate the
sequelae associated with endoluminal stenting, to include
restenosis in vessels and reocclusion in other tubular anatomical
structures to which the stent is itself a contributing factor if
not the triggering or sole cause, fracture, fragmentation,
migration as intact or following breakage, clogging, and erosive
irritation to the portions of the lumen in contact with the stent,
thereby achieving stenting action that remains trouble-free even to
the end of life.
[1444] 18. Interventional procedures that compared to ablation or
angioplasty and stenting by conventional means, yield a relatively
low incidence of adverse sequelae, and compared to open surgery,
are significantly less traumatizing, making these procedures
applicable to a larger patient population.
[1445] 19. Limited purpose interventional airguns at relatively low
cost through modification of off the shelf airguns.
[1446] 20. Special interventional airguns that provide finer
control through multiple control points that reduce the dependency
of adjustment on any single control point and make possible the
quick and precise adjustment of the exit velocity and force of
penetration.
[1447] 21. Interventional apparatus and procedures that allow
angioplasty, atherectomy, and stenting with single endoluminal
entry, minimizing intracorporeal time and entry wound trauma and
complications.
[1448] 22. Apparatus for use in the vascular tree that affords
operative speed with minimal ischemia and without a thrombogenic
metal in the lumen.
[1449] 23. Extraluminal stenting that complies with the intrinsic
motility in the ductus wall, leaves the lumen clear of any foreign
object in the form of an artificial lining, or stent, that can
clog, fracture, migrate, migrate and induce an abrupt closure that
could result in an infarction and death, is a source of chronic
irritation, interferes with normal function, and perpetuate the
need for adjunctive medication such as antithrombogenic,
anticoagulative, or thrombolytic posing a bleeding threat that
would complicate any surgical procedure to follow.
[1450] 24. Targeted implantation in the walls of ductus of
radioactive seeds, which low dose-rate, can be left in place or
high dose-rate, can be recovered at will, using the same apparatus
that was used to implant the seeds.
[1451] 25. A periductal or circumductal prosthesis that expands and
contracts with the arterial wall so as to cause the least low
oscillating shear stress and turbulence in the flow of blood and
does not compress the vasa vasora to induce atheromatous lesioning
(as seen in .sup.Silastic.RTM. collar experiments), and which when
applied to other type ductus, complies with peristalsis, and
remains chemically isolated from the surrounding environment. 26.
Prepositioned means for preventing embolization or the spread to
nontargeted tissue of radiation or medication by any miniballs that
should enter the lumen.
[1452] 27. Apparatus for use in the vascular system that allows
lower doses and periprocedural limiting of anticlotting drugs,
hence, shorter infusion of abciximab and oral administration of
clopidogrel times of platelet inhibitor-type antithrombogenics, or
aggregation counteractants and anti-inflammatory corticosteroids,
for example.
[1453] 28. The foregoing where the use of conventional stenting
poses the risks of bleeding or stent thrombosis for surgery
following stent placement.
[1454] 29. Methods and apparatus that afford fine discretionary
control over the location and intensity of treatment, thereby
minimizing iatrogenic interference with the intrinsic potential of
the vessel or organ to heal and recover normal function.
[1455] 30. Lay the groundwork for the direct piping to the
treatment site through stent-jackets as described herein as
modified in copending application Ser. No. 14/121.365 to receive
drug and other agent feedlines from a small port a the body
surface, for example, as well as through tissue surface connectors
as described in copending application Ser. No. 14/998,495.
[1456] 31. Lay the groundwork for the application of adaptive
hierarchical control to the automatic treatment of morbidity and
coordinated treatment of comorbidities.
[1457] 32. Set forth the concept of adaptive hierarchical control
systems for the automatic treatment of a morbid disorder and
coordinated treatment of comorbidities which fully implanted or
nearly so, are ambulatory, with implanted sensors able to detect
the earliest indications of deviations from the normal range in
therapeutically relevant physiological functions and initiate the
directly targeted delivery of drugs to reverse these, often before
symptoms appear to consciousness, in accordance with the
prescription program executed by the implanted microprocessor.
[1458] These and other objects and advantages of the invention will
become apparent from the following specification and accompanying
drawings. Further scope in the applicability of the invention will
become apparent from the detailed descriptions of the preferred
combinations of components, assemblies, and methods, or the
embodiments to be described herein. Since various modifications in
keeping with the concept and scope of the invention will be
evident, the detailed specification is given only by way of
illustration. The invention accordingly comprises the features of
construction, combination of elements, and arrangement of parts
exemplified in the constructions hereinafter set forth, and the
scope of the invention will be indicated in the claims.
[1459] All drugs which can be put in biocompatible solution can be
pipe-targeted, to include include glycoprotein IIb/IIIa receptor
blockade or antagonist (abciximab), and lower doses of thrombolytic
drugs, thus reducing the risk of bleeding complications (see also,
for example, Lebozec, K., Jandrot-Perrus, M., Avenard, G.,
Favre-Bulle, O., and Billiald, P. 2017. "Design, Development and
Characterization of ACT017, a Humanized Fab that Blocks Platelet's
Glycoprotein VI Function Without Causing Bleeding Risks,"
Monoclonal Antibodies 9(6):945-958; Bosch, X., Marrugat, J., and
Sanchis, J. 2013. "Platelet Glycoprotein IIb/IIIa Blockers During
Percutaneous Coronary Intervention and as the Initial Medical
Treatment of Non-ST Segment Elevation Scute Coronary Syndromes,"
Cochrane Database of Systematic Reviews (11):CD002130; Lenderink,
T., Boersma, E., Ruzyllo, W., Widimsky, P., Ohman, E. M.,
Armstrong, P. W., Wallentin, L., Simoons, M. L. 2004. "Bleeding
Events with Abciximab in Acute Coronary Syndromes Without Early
Revascularization: An Analysis of GUSTO IV-ACS [Global Utilization
of Strategies To open Occluded arteries-Intravasular-Acute Coronary
Syndrome-intravascular-acute coronary syndrome]," American Heart
Journal 147(5):865-873; Cote, A. V, Berger, P. B., Holmes, D. R.,
Scott, C. G., and Bell, M. R. 2001. "Hemorrhagic and Vascular
Complications after Percutaneous Coronary Intervention with
Adjunctive Abciximab," Mayo Clinic Proceedings 76(9):890-896; Jong,
P., Cohen, E. A., Batchelor, W., Lazzam, C., Kreatsoulas, C.,
Natarajan, M. K., and Strauss, B. H. 2001. "Bleeding Risks with
Abciximab After Full-dose Thrombolysis in Rescue or Urgent
Angioplasty for Acute Myocardial Infarction," American Heart
Journal 141(2):218-225). In lower doses, these drugs are of
critical value perioperatively (see, for example, Tcheng, J. E.,
Kandzari, D. E., Grines, C. L., and 11 other authors 2003.
"Benefits and Risks of Abciximab Use in Primary Angioplasty for
Acute Myocardial Infarction: The Controlled Abciximab and Device
Investigation to Lower Late Angioplasty Complications (CADILLAC)
Trial," Circulation 108(11):1316-1323).
SUMMARY OF THE INVENTION
[1460] The foregoing objects as pertain to stenting are
accomplished in accordance with the invention by means of miniature
balls called miniballs or arcuate bands called stays. These include
ferrous matter and are implanted just beneath the outer tunic of a
ductus or organ. This position is outside the physiologically more
active inner layers, and inside the more fibrous outer layers that
serve to retain the miniballs or stays. Miniballs and stays can
consist primarily of a therapeutic substance, time-released drug or
drugs, or a radionuclide in any combination, the ferrous content
allowing the quick recovery of any miniballs or stays that are
dropped or mispositioned. The apparatus for infixing each type
implant is described. Implanting stays avoids the lumen entirely.
The apparatus for implanting miniballs incorporates non-balloon
means for performing an ablation or an angioplasty, allowing the
lumen to be prepared and implanted with single entry and
withdrawal.
[1461] Provided with a short side connector or connectors, stent
and impasse-jackets as described herein, as well as those described
in copending applications Ser. No. 14/121,365 and Ser. No.
14/998,495, can be connected by catheter or catheters to a small
port at the body surface with protected openings to allow the
directly targeted infusion of different drugs, for example, in
isolation from one another, the bloodstream, and tissue along the
route to different jackets and connectors. Delivery thus can be
placed under the control of an automatic drug delivery response
system wherein an implanted microprocessor taking inputs from
sensor implants directs the dispensing of drugs according to the
prescription program it executes, monitors the results, and
registers this data, thus implementing an adaptive hierarchical
control system. In this way, drug delivery is coordinated to
approximate normal homeostasis as can best be accomplished given
the overall condition of the patient. By connection to the blood
supply and/or the organ or tissue itself, these jackets and
connectors allow the direct delivery of drugs to any organ or
tissue.
[1462] (Balance of abstract) System components make possible drug
targeting by implantation within the walls surrounding lumina, a
segment of a ductus, an entire organ, or a portion thereof.
Implants that include ferromagnetic material can be recovered or
used for extraluminal stenting. A magnetic extraluminal stent
consists of an intravascular component in the form of perimedially
or medially implanted miniballs or stays and an extravascular
magnetized collar or mantle that is pliant, protectively lined, and
slit along one side. The use of more distant magnet implants
likewise leaves the lumen free of any foreign object. The
unrestraining and vasomotion-compliant stent can remain in place
indefinitely and be applied, for example, to as yet unaffected
segments of an artery to prevent a need for revascularization;
however, should another transluminal procedure be needed, the lumen
will be clear. Extraluminal stents can be used to attract magnetic
drug or radioisotope carrier particles, adapted to allow for
changes in caliber, and linked to negotiate bends or accommodate
flexion.
[1463] Delivery targeted, the dose is optimal with dispersion to
nontargeted tissue and side effects minimized. When magnetized,
these and the other type implants described can be used to attract
drug carrier particles passing through the lumen. When drawn
radially outward toward a compliant mantle that is itself
magnetized or has magnets mounted about its outer surface, the
implants are drawn to the mantle and therefore draw the wall of a
stenosed or collapsed ductus outward with a force just sufficient
to maintain the lumen patent. The ductus-intramural implants then
act as the intravascular and the mantle as the extravascular
components of an extraluminal stent that leaves the lumen free of
any foreign object. Multiple means for preventing a miniball loose
in the circulation from embolizing are provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[1464] A more complete understanding of the invention can be
obtained by reference to the accompanying drawings of which:
[1465] FIG. 1 depicts the interrelations among the various
components described herein as constituting an integrated
system.
[1466] FIG. 2 is a diagrammatic longitudinal section view of a vas
or ductus such as the trachea with ferromagnetic spherules
implanted just within the tunica adventitia or tunica fibrosa which
are drawn outward toward a circumvascular jacket of the extrinsic
spaced apart magnet type with tiny magnets mounted about its outer
surface. For simplicity and generalization to allow applicablility
to different type ductus, histological detail has been omitted.
[1467] FIG. 3 is a diagrammatic longitudinal section view of a
vessel, such as an artery or ureter, mantled about by a side-slit
or side-slotted circumvascular stent-jacket of the extrinsic spaced
apart magnet type, the increased density and uniform distribution
of ferromagnetic miniball implants accomplished with the aid of a
positional control system serving to reduce the risk of
pull-through. For simplicity and generalization to allow
applicablility to different type ductus, histological detail has
been omitted.
[1468] FIG. 4 is a diagrammatic cross sectional view of the lumen
taken along line A-A' in FIGS. 2 and 3 with ferromagnetic spherules
or miniballs implanted just inside the fibrous outermost layer, or
tunica adventitia, which is mantled about by a stent-jacket of the
extrinsic spaced apart magnet type as shown in FIGS. 2 and 3.
[1469] FIG. 5 is an angular perspective show-through or ghost view
of the full-round extraductal stent-jacket component of an
extraluminal stent for a vessel or duct that can be fully encircled
as shown in FIGS. 2 and 3 showing the apposed or facing relation
between the subadventitial implants and the magnets surrounding the
base-tube in the extrinsic spaced apart magnet type stent-jacket
with gas exchange apertures or perforations as shown in FIG. 6
omitted for clarity.
[1470] FIG. 6 is an angular perspective view of a stent-jacket for
a vessel or ductus which cannot be fully encircled without a
widened slde-slit, or side-slot, for clearing a connective tissue
attachment wished preserved or a branch or branches, for example,
of the treated ductus. The gas-exchange or `breathing` perforations
shown can be of any shape or number and incorporated into any
stent-jacket.
[1471] FIG. 7 is an angular perspective view of a stent-jacket with
a nonlayered expansion insert in its side-slit or side-slot to
allow approximation of the side-slit or side-slot apposing edges
once swelling of the ductus subsides. Magnets as shown in FIGS. 2
thru 6, `breathing` holes as shown in FIG. 6, and optional
side-straps shown as in FIGS. 13 thru 15 have been omitted.
[1472] FIG. 8 is a cross-sectional detail view taken along line
B-B' in FIG. 7 of a bilaterally symmetrical multilayered
stent-jacket expansion insert for insertion in the side-slit or
side-slot of a stent-jacket that opens at the center to accommodate
expansion of the substrate ductus, wherein the more medial layers
are absorbed at progressively slower rates and the more lateral
layers are lithotriptor-destructible on demand.
[1473] FIG. 9 is a cross sectional view taken along line B-B' in
FIG. 7 of an extended stent-jacket expansion insert wherein the
medial layers are absorbable and the lateral layers
lithotriptor-destructible on demand. The quasi-intrinsically
magnetized stent-jacket incorporates encapsulated neodymium iron
boron granules (not depicted).
[1474] FIG. 10 is a diagrammatic longitudinal section view through
a stent-jacket of the extrinsic spaced apart permanent bar magnet
type with a longitudinally noninclined lining of moisture
barrier-coated viscoelastic polyurethane foam showing a miniball
that has perforated through the adventitia and rebounded off the
internal surface of the base-tube without sufficient residual
momentum to escape entrapment within the moisture barrier-coated
viscoelastic polyurethane foam and penetrate into the lumen.
[1475] FIG. 11 is a diagrammatic longitudinal section view through
a stent-jacket of the extrinsic spaced apart magnet type with a
longitudinally noninclined lining of moisture barrier-coated
viscoelastic polyurethane foam showing a miniball that has forced
the adventitia through the foam lining up against the internal
surface of the base-tube with sufficient momentum that the miniball
has rebounded into the lumen.
[1476] FIG. 12 is a diagrammatic longitudinal section view through
a stent-jacket of the extrinsic spaced apart magnet type with a
base-tube that increases in thickness from one end to the other and
an angularly complementary or wedge-shaped moisture barrier-coated
viscoelastic polyurethane foam lining where a miniball has forced
the adventitia through the foam lining against the internal surface
of the base-tube with sufficient momentum to rebound toward the
lumen but deflected at the equal but opposite angle by the inclined
surface to become embedded within the ductus wall rather than
perforate into the lumen.
[1477] FIG. 13 is a perspective view of a chain stent-jacket of the
segmented extrinsic spaced apart magnet type in the form of an
iterative module substents along a continuous length of base-tubing
from which one or more stent-jacket modules can be snipped off
midway between the side-straps.
[1478] FIG. 14 is a longitudinal side view of a single
extrinsically magnetized stent-jacket module segment or substent
which has been cut from the continuous segmented stent-jacket shown
in FIG. 13 by placing cuts midway between the adjacent
end-straps.
[1479] FIG. 15 is a side view showing a nonmagnetized jacket, which
can be a module cut from a segmented chain-stent, that varies in
that the straps used to gird about or cinch the ductus are
side-straps rather than end-straps, hence, suitable for containing
an incipient aneurysm.
[1480] FIG. 16A is a perspective view of the proximal stabilizing
dummy collar, or outrigger, of a compound impasse-jacket shown in
its entirety in FIG. 16B.
[1481] FIG. 16B is a perspective view of a compound impasse-jacket
shown in its entirety.
[1482] FIG. 16C is a perspective view of one of the bendable
bridges used to join stabilizing dummy collars, that proximal shown
in FIG. 16A, of a compound impasse-jacket to the impasse-jacket
proper shown in FIG. 16B.
[1483] FIG. 17 is a side view of a long-handle tweezers- or
tongs-configured (thumb forceps) stent-jacket applicator, or
base-tube slit-expansion and mantling hand tool for use with deep
lying ductus, in which the restorative or spring force intrinsic in
the junction joining the arms forces open the stent-jacket for
placement about the ductus when compression of the tool arms
between the thumb and index finger is released.
[1484] FIG. 18 is a side view of a short-handle tweezers or
tongs-type (thumb forceps) stent-jacket insertion tool, applicator,
or base-tube slit-expansion and mantling hand tool for use with
ductus that lie close to the surface of the body, in which the
restorative or spring force intrinsic in the junction joining the
arms forces open the stent-jacket for placement about the ductus
when compression of the tool arms between the thumb and index
finger is released.
[1485] FIG. 19 is a side view of a short forceps-type or scissors,
crile, or needle holder-configured stent-jacket insertion tool,
applicator, or base-tube slit-expansion tool, for use with ductus
that lie near the body surface.
[1486] FIG. 20 is a side view of a long-handle forceps or scissors,
crile, or needle holder-configured stent-jacket insertion tool,
applicator, or base-tube slit-expansion and stent- or
impasse-jacket mantling tool for use with deep lying ductus.
[1487] FIG. 21A is a full face-on view of an unwrapped, laid opened
flat magnet-wrap.
[1488] FIG. 21B is a left edge-on longitudinal section view taken
along line C-C' in FIG. 21A showing the plies separated and
moisture barrier-coated viscoelastic adventitia or
fibrosa-protective polyurethane foam lining to the right.
[1489] FIG. 22 is a full-face view of an open clasp-wrap.
[1490] FIG. 23 is a detailed overhead or plan view of a single
clasp in the clasp-wrap shown in FIG. 22.
[1491] FIG. 24 is a detailed cross-sectional view along line D-D'
of the individual clasp shown in FIG. 23 with moisture
barrier-coated viscoelastic polyurethane foam lining.
[1492] FIG. 25 is a full face overhead or plan view of a patch- or
clasp-magnet for attracting ferromagnetic ductus-intramural
implants, drug-carrier nanoparticles, or a clasp-wrap by attachment
suprapleurally or to epimycial or visceral fascia whether
subcutaneous, for example.
[1493] FIG. 26 is cross sectional view taken along line E-E' in
FIG. 25 of a patch-magnet shown without the moisture barrier-coated
viscoelastic polyurethane foam lining, for attracting ferromagnetic
ductus-intramural implants, drug-carrier nanoparticles, or a
clasp-wrap by attachment suprapleurally or to epimycial or visceral
fascia whether subcutaneous, for example.
[1494] FIG. 27 is a cross-sectional view through a miniball which
contains magnetically susceptible ferrous matter and can include a
radiation-emitting seed or a heat-radiating radiofrequency
alternating magnetic field resonant circuit as or within its
ferromagnetic core and concentric layers of medication.
[1495] FIG. 28 is a cross-sectional view through a miniball which
can incorporate a radioactive seed or a heat-radiating
radiofrequency alternating magnetic field resonant circuit in the
core (not shown) such as that shown in FIG. 27, with additional
sequentially released layers of medication, other therapeutic
substances, and a solid protein solder outer envelope that flows
when heated.
[1496] FIG. 29 is a full-face view of a 7-shot rotary magazine clip
for use in a single barrel (single barrel-tube, monobarrel) radial
discharge barrel-assembly.
[1497] FIG. 30 is a full-face view of a 10-multishot rotary
magazine clip for use in a four barrel-tube or four-way radial
discharge barrel-assembly.
[1498] FIG. 31 is a longitudinal section view of a simple pipe-type
monobarrel barrel-assembly suitable for use in the tracheobroncial
tree, wherein the anatomy is structurally differentiated or where
each miniball implant should be precisely located in relation to
the lesion, shown without side-clips for attaching a laser sight
and fiberoptic bronchoscope or endoscope.
[1499] FIG. 32 is a longitudinal section view of a simple pipe-type
barrel-assembly with a deflection- or bounce-plate attachment for
reversing the direction of the trajectory of a miniball at an angle
equal and opposite to that of the initial impact against the
bounce-plate, shown without side-clips for attaching a laser sight
and fiberoptic bronchoscope or endoscope.
[1500] FIG. 33 is a detailed view longitudinal section through the
miniball recovery electromagnet enclosure and recovery
electromagnet affixed within the concavity of the distal curve of a
simple pipe type barrel-assembly such as those shown in FIGS. 31
and 32.
[1501] FIG. 34 is a perspective detail view, partly in section, of
the muzzle-head of the simple pipe barrel-assembly with a slip-on
type bounce-plate seen in the overall view of FIG. 32, showing the
reversal of the miniball trajectory at an angle equal and opposite
to that of the strike against the bounce-plate.
[1502] FIG. 35 shows a side view of a simple pipe barrel-assembly
such as that shown in FIG. 31, equipped with an endoluminal
bounce-plate deployment and retraction control mechanism of the
kinds shown in greater detail in FIGS. 36 and 37.
[1503] FIG. 36 is a longitudinal section through a curved
spring-steel, or spring-plate type bounce-plate mechanism for use
in a simple pipe-type barrel-assembly, which can be deployed,
rotated, and retracted, but not adjusted in deflection angle while
the pipe is endoluminal or intracorporeal, the bounce-plate
straightened when retracted or ensheathed.
[1504] FIG. 37 shows a longitudinal section through a simple pipe
barrel-assembly bounce-plate mechanism that hinged, allows the
bounce-plate not only to be deployed, rotated, and retracted but
adjusted in deflection angle while endoluminal or
intracorporeal.
[1505] FIG. 38 is a longitudinal section view through the
barrel-catheter of a single barrel, or monobarrel, radial-discharge
barrel-assembly, the muzzle-head shown externally to allow its
parts to be defined. An optional forward drive and sag leveling and
stabilizing device distal to the twist-to-lock connecting flange is
shown in FIGS. 77 and 78.
[1506] FIG. 39 is a longitudinal section through the
barrel-catheter of a 2- or 4-barrel-tube multibarrel ablation or
angioplasty-incapable (plain discharge, limited purpose)
radial-discharge barrel-assembly, with a nearer than median view of
the muzzle-head without a convoluted joining section and radial
projection units of an ablation or an ablation and
angioplasty-capable barrel-assembly as seen in FIGS. 48 and 49,
showing the parts within the muzzle-head. An optional forward drive
and sag leveling and stabilizing device distal to the twist-to-lock
connecting flange is shown in FIGS. 77 and 78.
[1507] FIG. 40 is a cross-sectional view through the mniball
recovery magnet chambers of a barrel-assembly taken along line H-H'
in FIG. 39 with the muzzle-head rotated by 90 degrees.
[1508] FIG. 41 is a mid-longitudinal-section detail of the internal
structure of a barrel-catheter as shown in FIG. 39 which has been
longitudinally condensed to include both a blood-tunnel as in the
plane indicated by line F-F' in FIG. 39 and a centering device as
in the plane indicated by line G-G' in FIG. 39.
[1509] FIG. 42 is a view partly in cross-section along line G-G' in
FIG. 41 through a centering device perforated by blood-tunnels
which are depicted perspectively as receding into the distance in
an ablation or angioplasty-incapable four-barrel radial discharge
barrel-assembly.
[1510] FIG. 43 is a full-face cross-section view along line G-G' in
FIG. 41 through a centering device in a center-discharge ablation
or angioplasty-incapable four barrel-tube radial discharge
barrel-assembly wherein the barrel-catheter is relatively large in
diameter.
[1511] FIG. 44 is a full-face cross-sectional view as if taken
along line G-G' in FIG. 41 through a centering device in an
ablation or angioplasty-incapable four-barrel radial discharge
barrel-assembly suitable for use in an edge-discharge
barrel-assembly or in a barrel-assembly that places the
barrel-tubes more distant radially from the longitudinal axis of a
relatively large diameter barrel-catheter.
[1512] FIG. 45 is a full-face cross-sectional view as if taken
along line G-G' in FIG. 41 through a centering device of a
center-discharge ablation or angioplasty-incapable four-barrel
radial discharge barrel-assembly that places the barrel-tubes less
distant radially from the longitudinal axis of a relatively small
diameter barrel-catheter.
[1513] FIG. 46 is a perspectival view of an airgun valve-body that
incorporates a sliding pressure-bleed valve.
[1514] FIG. 47 shows a detail view of the sliding pressure-bleed
valve shown in FIG. 46.
[1515] FIG. 48 is a mid-longitudinal section through a 2- or
4-barrel-tube ablation or angioplasty-incapable center-discharge
muzzle-head with recovery electromagnets oriented or chambered
normal to the long axis of the barrel-assembly.
[1516] FIG. 49 is a mid-longitudinal section through a 2- or
4-barrel-tube ablation and angioplasty-capable center-discharge
muzzle-head with radial projection units and recovery
electromagnets oriented or chambered normal to the long axis of the
barrel-assembly, and equipped with an embolic trap-filter which as
shown in FIG. 50 is deployed or in this Fig. unstowed (retracted,
stowed) by means of the plunger solenoid 172 at the bottom of the
filter silo in the extended nose.
[1517] FIG. 50 is a diagrammatic detail view of the nose of a
barrel-assembly muzzle-head showing the embolic trap-filter 173 and
plunger solenoid 172 used to unstow or deploy and stow or retrieve
the trap-filter shown in FIG. 49 with the trap-filter deployed.
[1518] FIG. 51A is an exploded or breakout schematized detail view
of a radial projection unit, the hatch lines indicating its
position in the ablation and angioplasty-capable center-discharge
muzzle-head shown in FIG. 49, part number 174 designating a
tool-insert raised into projected working position by coiled
thermal expansion wire 177.
[1519] FIG. 51B is a diagrammatic view of the first of four
differently configured projection bristles or aristae working tips
of a curettage (evidement, scraper abrader-type) tool-insert shown,
the action of which depends upon the motion imparted to it by the
turret motor, such as rotational or oscillatory.
[1520] FIG. 51C is a diagrammatic view of the second of four
differently configured projection bristles or aristae working tips
of a curettage (evidement, scraper abrader-type) tool-insert shown,
the action of which depends upon the motion imparted to it by the
turret motor, such as rotational or oscillatory.
[1521] FIG. 51D is a diagrammatic view of the third of four
differently configured projection bristles or aristae working tips
of a curettage (evidement, scraper abrader-type) tool-insert shown,
the action of which depends upon the motion imparted to it by the
turret motor, such as rotational or oscillatory.
[1522] FIG. 51E is a diagrammatic view of the fourth of four
differently configured projection bristles or aristae working tips
of a curettage (evidement, scraper abrader-type) tool-insert shown,
the action of which depends upon the motion imparted to it by the
turret motor, such as rotational or oscillatory.
[1523] FIG. 52A is a diagrammatic longitudinal section view through
an expansion wire-lifted electrically operated radial projection
unit with curettage (evidement, scraper abrader-type) tool-insert
shown in FIG. 51C engaged within the holding and lift-platform
raised slightly short of the upward limit.
[1524] FIG. 52B is a diagrammatic longitudinal section view through
a fluidically operated radial projection unit with the same
curettage or evidement tool-insert shown in FIG. 51C engaged within
the holding and lift-platform as that shown in FIG. 52A raised
slightly short of the upward limit.
[1525] FIG. 52C is a nonprojecting or stationary fluidically
operated ejection-irrigation aspiration unit, which unlike the
interchangeable tool-insert accepting bidirectional units shown in
FIGS. 59, 60, and 63, can aspirate only once the supply line and
inflow and outflow chambers have been emptied.
[1526] FIG. 53A shows an exploded perspective view of the expansion
wire electrically operated radial projection unit shown in FIG. 52A
with the lift-shaft 174 lumen-adaxial (at the bottom), the
tool-insert holding and lift platform 176 radially outward thereto
(above the lift-shaft, at the center), and evidement or scraper
abrader-type ablation interchangeable tool-insert 184 lumen-abaxial
thereto adintimal, adendothelial (at the top of the figure)
inserted into lift-shaft 176 at the center of the figure.
[1527] FIG. 53B shows an alternatively insertable cutter-shaver
type tool-insert 184 in lieu of that shown in FIG. 53A.
[1528] FIG. 53C shows a blank or push-arm type tool-insert used to
push against the intima thereby to nudge the barrel-assembly
muzzle-head (or radial projection catheter if so equipped) in the
opposite direction.
[1529] FIG. 54 shows a thermal expansion wire electrically operated
(tool-insert lifting and lowering) radial projection unit with a
spring discharged electrical/fluid system-neutral injection syringe
tool-insert engaged in the tool-insert holding and lift-platform.
The tool-insert is not in use and retracted but positioned flush
against the lumen wall, having been lifted by the thermal expansion
wire at the bottom of the lift-shaft. The electrical socket in the
lift-platform is provided for use with other interchangeable
tool-inserts that require electrical power to operate internal
functions.
[1530] FIG. 55 shows an electrically operated (tool-insert lifting
and lowering) radial projection unit with a mechanical ejection
syringe tool-insert inserted therein, so that lifting is by the
coiled thermal expansion wire at the bottom, the electrical socket
for use with other interchangeable tool-inserts and therefore not
used.
[1531] FIG. 56 shows a compound mechanical-electrochemically
operated radial projection unit with an electrochemically lifted
and discharged injection syringe tool-insert engaged, wherein the
lifting expansion coil at the bottom of the lift-shaft beneath the
lifting platform is not energized, the tool-insert instead lifted
when contact of the needle point against the intima closes a
circuit that causes current arriving through the socket to be
passed through and melt the wax barrier separating chemicals that
liberate a gas when mixed.
[1532] FIG. 57 depicts a series, rather than parallel or
independently wired electrically energized tool-inserts,
specifically, that of the compound mechanical-electrochemical
tool-insert with gas generating reactive chemicals separated by a
wax barrier melting wire such as one made of nichrome shown in FIG.
56, into which series-parallel paths and additional circuit
elements can be introduced to energize alike or differentially one
or more electrically or fluidically operated (lifted) radial
projection unit tool-inserts or an electrochemically discharged
injection tool-insert as shown in FIG. 56 or tool-inserts that heat
their contents, for example.
[1533] FIG. 58 depicts the equivalent fluidic circuit to the series
wired electrical circuit shown in FIG. 57, such that all
tool-inserts in the series must irrigate or aspirate in unison,
whereas separate circuits would allow one, alternate, or all but
one tool-inserts, for example, to flush the lumen wall at the same
time that another, alternate, those following the irrigators, or
others downstream aspirate the irrigation fluid whether water or a
therapeutic solution.
[1534] FIG. 59 shows a fluidically operated radial projection unit
with a spring discharged compound mechanical electrical/fluid
system-neutral injection syringe inserted therein.
[1535] FIG. 60 shows a fluidically operated radial projection unit
with an initial prefill-delivering and thereafter fluid line
flow-through fed injection tool-insert inserted therein, the arrows
designating the antegrade direction of flow, which would be
reversed during retrograde flow.
[1536] FIG. 61 is a detail of a perforated passive fluid resistor
roof-plate for the outlet chamber of a fluid radial projection unit
lifting mechanism as incorporated into the fluidically operated
radial projection units shown in FIGS. 59 and 60, which is hinged
and has a wing or foil to pull the plate down and close it during
injection (antegrade, forward) flow and partially push up to lift
it up out of the fluid path during aspiration (retrograde, reverse)
flow, thereby increasing the interval the resistor remains
unclogged by a buildup of debris.
[1537] FIGS. 62 panel A and 62 panel B show a perforated
damper-configured passive fluid resistor ejection-aspiration
switching valve as incorporated into the fluid operated radial
projection units shown in FIGS. 59, 60, and 63, hinged to cant
adaxially or downward toward the fluid supply line during
aspiration, as shown in FIG. 62 panel B, thus avoiding clogging by
debris, but to swing upward until stopped during ejection when
needed as a fluid resistor, as shown in FIG. 62 panel A.
[1538] FIG. 63 shows a fluidically operated radial projection unit
with an initial prefill-delivering and thereafter fluid line
flow-through fed delivering ejection-irrigation-aspiration
tool-insert inserted therein, the arrows designating the antegrade
direction of flow, which would be reversed during retrograde
flow.
[1539] FIG. 64 is a full face external view of acenter-discharge
ablation and angioplasty-capable center-discharge muzzle-head body
such as that shown in FIG. 49 to show slit (rather than all-around)
type heat-windows overlying the turret-motor and forward recovery
and filter deployment plunger solenoid electromagnets.
[1540] FIG. 65 is a mid-longitudinal or median section through the
center-discharge muzzle-head of a 2- or 4-barrel-tube ablation and
angioplasty-capable barrel-assembly equipped with radial projection
units, recovery electromagnets oriented in parallel relation to the
long axis of the barrel-assembly with miniball recovery magnet
trap-chambers or antechambers oriented as shown in the
cross-section of FIG. 67 (not shown as lying perpendicular to the
plane of section), and a trap-filter as shown in FIGS. 49 and 50
that is unstowed or deployed from and retracted into or stowed in a
silo within the nose of the muzzle-head by a plunger solenoid.
[1541] FIG. 66 is a mid-longitudinal or median section through the
edge-discharge muzzle-head of a 2- or 4-barrel-tube
combination-form ablation and angioplasty-capable edge-discharge
barrel-assembly equipped with radial projection units, miniball
recovery electromagnets and trap-chambers or antechambers oriented
in parallel relation to the long axis of the barrel-assembly with
recovery magnet trap antechambers oriented as shown in the
cross-section of FIG. 67 (not shown as lying outside the plane of
section), passed through the central channel
[1542] FIG. 67 is a diagrammatiic cross-section through the distal
section of the muzzle-head in an ablation and angioplasty-capable
combination-form (edge-discharge) barrel-assembly such as that
shown in FIG. 66 along line J-J' showing the eccentric (off-axis,
lateral) location of the trap-filter silo when the central channel
is taken up by a fiberoptic endoscope, cabled ablation, or
atherectomy device, whether the miniball recovery electromagnets
are parallel or perpendicular to the longitudinal axis of the
muzzle-head.
[1543] FIG. 68 is a mid-longitudinal or median section through a
capped side-emitting type cooling catheter.
[1544] FIG. 69 is a cross-section along line I-I' through the
cooling catheter of FIG. 68.
[1545] FIG. 70 is a diagrammatic mid-longitudinal or median section
through a heat-window created by passing a `cooling`
(temperature-changing) catheter connected to a vortex tube `cold`
air gun down the central channel of an edge-discharge type
muzzle-head such as shown in FIG. 66 to the nose.
[1546] FIG. 71A is a radial projection catheter with its own
unitized power and control housing allowing its use separately from
the barrel-assembly shown in FIG. 71B, but also combinable
therewith to constitute the duplex, or bipartite, ablation and
angioplasty-capable barrel-assembly shown in FIG. 71C.
[1547] FIG. 71B is a barrel-assembly with its own unitized power
and control housing complementary or matched in size to the radial
projection catheter shown in FIG. 71A so that when slid over and
along the proximal end of barrel-catheter 44, the combination of
the radial projection catheter shown in FIG. 71A and the
barrel-assembly shown in FIG.71B constitute the duplex, or
bipartite, ablation and angioplasty-capable barrel-assembly shown
in FIG. 71C.
[1548] FIG. 71C is a duplex or bipartite ablation and
angioplasty-capable barrel-assembly comprised of the radial
projection catheter shown in FIG. 71A and the barrel-assembly shown
in FIG. 71B.
[1549] FIG. 72 is a detailed view of the proximal end-plate of a
double barrel-tube radial discharge barrel-assembly showing the
proximal terminal for the electrical connection of the components
internal to the barrel-assembly, such as the recovery
electromagnets and radial projection units, connection established
when the barrel-assembly is engaged within the airgun chamber.
[1550] FIG. 73 is a detailed perspective view of a push and
twist-to-lock connecting flange or flat bayonet type connector
affixed to the muzzle of the airgun into which the male part of the
connector is inserted then rotated to be engaged, such a connector
used to lock a barrel-assembly of any kind within the barrel of any
kind of interventional airgun with or without a forward drive and
sag leveling and stabilizing device.
[1551] FIG. 74 is a longitudinal sectional view of the
barrel-catheter of a double barrel-tube radial discharge
barrel-assembly having an airgun connector such as that shown in
FIG. 73 locked in position within the chamber of the airgun.
[1552] FIG. 75 is a longitudinal view, partly external and partly
in section, of a side-socket electrical, fluid, or electrical and
fluid connection as alternative or additional to the end-plate
connection shown in FIGS. 73 and 74, which distal to and separate
from the connection of the barrel-assembly made by engagement in
the airgun chamber, can be used, for example, to render an ablation
or ablation and angioplasty-capable barrel-assembly
airgun-independent for power while allowing immediate access for
coupling fluid lines or inserting cables such as endoscopic, laser,
or cutting tool midprocedurally.
[1553] FIG. 76A is a side view of a scissors extension-type forward
drive and sag leveling and stabilizing linkage device for
interposition between the airgun and the barrel-assembly power and
control housing for extension over the barrel-catheter to prevent
sagging or sideways deviation when said device is expanded whether
the airgun is moved by hand or a linear positioning stage as shown
in FIG. 78C.
[1554] FIG. 76B is an overhead view of the scissors extension-type
forward drive and sag leveling and stabilizing linkage device shown
in FIG. 76A.
[1555] FIG. 77A shows an alternative forward drive, sag-leveling,
and stabilizing linkage device to that shown in FIGS. 76A and 76B
when fully extended, or expanded.
[1556] FIG. 77B shows the forward drive, sag-leveling, and
stabilizing linkage device shown extended in FIG.77A when fully
retracted, or contracted.
[1557] FIG. 77C shows a cross section of the forward drive,
sag-leveling, and stabilizing linkage device shown in FIGS. 77A and
77B taken along line K-K' in FIG. 77B.
[1558] FIG. 78A shows the duplex or bipartite ablation and
angioplasty-capable barrel-assembly comprised of the radial
projection catheter shown in FIG. 71A and the barrel-assembly shown
in FIG. 71B then shown combined in FIG. 71C before being further
integrated into the forward drive, sag-leveling, and stabilizing
linkage device shown in FIGS. 77B and 77C airgun barrel as shown in
FIG. 78C for stabilized precise control to allow the laying down of
a tight shot group pattern into the intima to avoid inequalities in
spacing and tension that would facilitate incisions.
[1559] FIG. 78B is a side view of the forward drive, sag-leveling,
and stabilizing linkage device shown in FIGS. 77B and 77C engaged
in the linear stage extension and retraction driver before
insertion of the barrel of the duplex, or bipartite, ablation and
angioplasty-capable barrel-assembly shown in FIGS. 71C and 78A.
[1560] FIG. 78C is a side view of the duplex, or bipartite,
ablation and angioplasty-capable barrel-assembly shown in FIGS. 71C
and 78A and the forward drive, sag-leveling, and stabilizing
linkage device engaged in the linear stage extension and retraction
driver when fully assembled.
[1561] FIG. 79 shows a simple control panel for a combination-form
ablation or ablation and angioplasty-capable barrel-assembly such
as shown in FIGS. 71 and 78 with heatable turret-motor stator,
heat-windows, evidement radial projection units, independently
heatable recovery or electromagnet windings, which allows the
insertion of an excimer laser, directional or rotary burr
atherectomizer, or a fiberoptic endoscope, for example, in the
central canal.
[1562] FIG. 80 shows a diagrammatic representation of the control
components and connections within the power and control housing of
a combination-form ablation or ablation and angioplasty-capable
barrel-assembly such as shown in FIGS. 71 and 78, wherein each
function is assigned to a separate rather than joint
microcontroller, the onboard control panel shown in FIG. 79.
[1563] FIG. 81 shows a longitudinal section view of a gravity fed
single barrel (single barrel-tube; monobarrel) interventional
airgun which incorporates plural control points for adjusting the
exit velocity over a range that allows its use for different
tissues at different angles and to different depths in quick
succession, shown with a plunger or dead-man switch type
trigger.
[1564] FIG. 82 shows a longitudinal section view of a gravity fed
single barrel (single barrel-tube; monobarrel) interventional
airgun with exit velocity control points in addition to those
incorporated into the airgun shown in FIG. 81 to allow quick
midprocedural adjustments, shown with a plunger or dead-man switch
dead-man switch type trigger.
[1565] FIG. 83 shows a diagrammatic representation of an automatic
positional control system for an interventional airgun, which can
be a gravity fed monobarrel such as those shown in FIGS. 81 and 82
or equipped with a rotary clip magazine such as those shown in
FIGS. 31 and 32 for use with multiple barrel-tube
barrel-assemblies, which advances, withdraws, and rotates the
muzzle-head in coordination with discharge to allow the uniform
implantation of miniballs in close-formation.
[1566] FIG. 84 shows a diagrammatic representation of the timing
and positional componentry used to coordinate the automatic
discharge as an auxiliary function and instantaneous positioning in
transluminal displacement and rotational angle of the muzzle-head
of an airgun such as those shown in FIGS. 81 and 82 but equipped
with a rotary clip magazine such as those shown in FIGS. 31 and 32
for use with multiple barrel-tubes to allow the accurate implantion
of miniballs in a close formation.
[1567] FIG. 85 shows a simple interventional airgun control panel
suitable for use with an airgun such as that shown in FIG. 81
having multiple barrel-tubes and supported by componentry such as
that shown in FIGS. 83 and 84 to allow the timing of discharges to
be coordinated with the instantaneous rotational and transluminal
position of the muzzle-head as an auxiliary function of the
positional control system, the additional controls for plunger
solenoid current and expulsive gas pressure as applies to the more
capable airgun shown in FIG. 82 not shown.
[1568] FIG. 86 shows a diagrammatic perspectival view of a ductus
that has been implanted with stays, whether ferromagnetic for
encirclement by a stent-jacket, medicinal, radiation seeds, some
combination thereof, or as structural buttresses, absorbable or
nonabsorbable.
[1569] FIG. 87 shows a right side-view partly in section as well as
a detailed view of the lower or working end of a control
syringe-configured depress-to-eject tissue
sealant/release-to-insert a stay, insertion passive-type stay
insertion tool which allows tissue sealant to be applied to the
stays upon ejection and the force of insertion to be set by the
restorative force of the plunger or slide return compression spring
but also allows force to be reduced or increased manually (front
and side mounting spring clips not shown).
[1570] FIG. 88 shows a full face front view of the upper portion of
the control syringe-configured stay insertion tool shown in FIG.
87.
[1571] FIG. 89 shows a longitudinal section through a
pistol-configured pull-type, active, or pull trigger to eject
tissue sealant, then inject a stay-type stay insertion tool.
[1572] FIG. 90 shows an enlarged view of the working or ejection
end of a stay insertion tool whether of the control
syringe-configured release to eject type shown in FIG. 87 or the
pistol-configured pull-trigger to eject type shown in FIG. 88 at
the end of the stay loading phase of the ejection cycle with stay
ejection blade fully retracted.
[1573] FIG. 91 shows a further enlarged view of the working or
ejection end of the stay insertion tool shown in FIG. 90 to allow
the parts thereof to be clearly seen.
[1574] FIG. 92 further enlarges the working end of the stay
insertion tool shown in FIG. 91 to show the articulation of a stay
by the tip of the stay ejection blade (stay ejection tongue,
plunger blade) at the working or ejection end of stay insertion
tools whether of the control syringe-configured release to eject
type shown in FIG. 87 or the pistol-configured pull-trigger to
eject type shown in FIG. 88.
[1575] FIG. 93 shows a longitudinal section through two consecutive
stent-stays, or stays containing ferromagnetic cores, in a refill
strip, showing the binding agent used to hold the stay refill in
one continuous strip from which the stay at the bottom is the next
to be ejected.
[1576] FIG. 94 shows a diagrammatic longitudinal sectional view of
a portion of a stay refill strip showing various layered coatings
that can be applied to a stay wherein the thickness of each layer
is exaggerated for clarity.
[1577] FIG. 95 shows a detailed section view of the sliding hole
pressure relief mechanism used to reverse the direction of the
starting height at which the cement or medication chamber
pressurization piston in a stay insertion tool exerts air pressure
on the column of cement or medication in the cement refill
cartridge, thus initiating ejection of the cement or
medication.
[1578] FIG. 96 shows a sectional side view of the
cement-ahead/cement-after subminiature sprocket and up or down run
of sprocket chain selection switching mechanism used to reverse the
direction as up or down of the cement pressurization piston which
is permanently fastened to one side of the chain when the
thumb-ring, and thus the small catch arm on the plunger-rod
(plunger-slide, slide, thumb rod, thumb shaft; thumb plunger; thumb
plunger-rod; plunger shaft; thumb plunger shaft), is rotated from
one side of the chain to the other.
[1579] FIG. 97 shows an overall side sectional view of the
cement-ahead/cement-after selection switching mechanism shown in
FIG. 96.
[1580] FIG. 98 shows an enlarged detailed sectional view at the
sprocket level of the cement ahead/cement-after selection switching
mechanism shown in FIGS. 96 and 97.
[1581] FIG. 99 is a cross-section through the upper portion of a
control syringe-configured release to inject stay insertion tool
along line L-L' in FIG. 87.
[1582] FIG. 100 shows a cross-section of the cement
ahead/cement-after switching mechanism along line M-M' in FIGS. 97
and 98.
[1583] FIG. 101A is a full-face frontal longitudinal section view
through a stay insertion tool auxiliary syringe holder mounting
frame and motor for attaching a commercial tissue sealant or
medication syringe which provides latitude in the number of
syringes or syringe chambers.
[1584] FIG. 101B is a face-on view of the right side of the stay
insertion tool auxiliary syringe holder mounting frame and motor
shown in FIG. 101A for attaching a commercial tissue sealant or
medication syringe which provides latitude in the number of
syringes or syringe chambers.
[1585] FIG. 102 shows a side view, as in FIG. 87, showing the
attachment to a stay insertion tool of an auxiliary syringe holding
frame and motor such as that shown in FIG. 101 by means of a
mounting cable-delivery extension line such as that shown in FIGS.
104 and 105, with the connection socket at the rear shown in FIG.
106.
[1586] FIG. 103 shows a left side sectional view of a stay
insertion tool auxiliary syringe holding frame and motor such as
shown in FIG. 102, showing at the bottom of the drawing, the
attachment of the frame and motor to the mounting cable-delivery
extension line.
[1587] FIG. 104 shows a detailed longitudinal sectional view of a
stay insertion tool auxiliary syringe mounting cable-delivery
extension line such as shown in FIGS. 102 and 103.
[1588] FIG. 105 shows a cross-section through the stay insertion
tool auxiliary syringe holding frame supporting arm and connecting
cable shown in FIGS. 102, 103, and 104.
[1589] FIG. 106 shows a detailed view of the right side and full
face rear views of the socket used to connect the auxiliary syringe
shown in FIGS. 101 thru 103 to a stay insertion tool showing the
break-contact terminals used to initiate the timing of tissue
sealant and/or medication delivery by controlling the electrical
current to the dual interval delay/on-timing module in slave
mode.
[1590] FIG. 107 shows a schematic for a single channel of control
in a fully implanted ambulatory adaptive hierarchical control
system for automatic response to a comorbid condition, wherein
medication is automatically dispensed from flat reservoirs placed
subdermally in the pectoral region for targeting directly to
side-entry jackets along one or more organ systems through piping,
this channel one of a number under adaptive or `self tuned`
hierarchical control of which the governing prescription program is
discharged by an implanted microcontroller.
[1591] FIG. 108 shows the overall plan of a fully implanted
adaptive ambulatory prosthetic disorder response system governed by
a control system organized hierarchically to provide a dedicated
channel of control to each of several different treatment sites or
organ systems as components of a comorbid condition, such control
discharged by an implanted microcontroller according to a
prescription program that coordinates the directly targeted
delivery of drugs to side-entry jackets such as that shown in FIG.
107, coordination among the channels directed to the optimal
sustainment of homeostasis.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[1592] FIG. 1 depicts the interrelations among the different types
of implants, and FIGS. 2 thru 5 one end-condition sought through
use of the methods and apparatus to be described. To apply to any
tubular anatomical structure, viz. any vas (vessel), or ductus
(duct), of adequate diameter, the figures omit histological detail.
Accordingly, FIGS. 2, 4, and 5 may be taken to represent the lumen
of a ureter, the esophagus, colon, trachea, or bronchus, and FIGS.
3, 4 and 5, which use the same part numbers for equivalent parts,
show the lumen of an artery or vein following treatment with the
apparatus and method to be described. Such treatment is not limited
to implantation, but depending upon the specific apparatus, can
include or consist of an ablation or an angioplasty using any or a
combination of several means, and the application or injection of
medication and/or any other fluid therapeutic substance, to include
a test solution, stain (dye, contrast), or a cement for
example.
[1593] FIG. 2 shows the extravascular component of an extraluminal
magnetic stent, or stent-jacket, with intravascular component
consisting of miniballs or stays about a generalized ductus, such
as a ureter, FIG. 3 the same with a more dense formation of
implants in a generalized vas, such as an artery or vein with the
stent-jacket about the vas or ductus, in longitudinal section,
while FIG. 4 shows this in cross section.
[1594] With a barrel-assembly that incorporates radial projection
units and heat-windows--and if a combination-form barrel-assembly,
a cabled device, such as an excimer laser, ultrasound angioplasty
probe, or directional or rotational cutting tool atherectomy
device--stenting discharge is initiated following preparation of
the lumen immediately, without the need to withdraw and reenter. A
simple barrel-assembly allows stenting without preparatory
treatment, or direct stenting, or stenting following ablation or
conventional balloon angioplasty, atherectomy, or both.
[1595] In FIGS. 2 thru 5, vas or ductus 1 has implanted just inside
the outer fibrous layer, whether tunica fibrosa or adventitia 2 of
its wall 7, ferromagnetic spherules or miniballs 3. Pulled outward
by small bar magnets 4, usually made of neodymium iron boron
lanthanoid mounted about the outer surface of surrounding length of
pliant tubing, or base-tube 5, miniballs 3 draw the ductus wall 7
outward and so maintain the passageway or channel that courses
through the ductus 8, or its lumen, open, or patent. Extravascular
or extraductal stent component, referred to as a stent-jacket, 6
consists of base-tube 5 with moisture barrier-coated viscoelastic
polyurethane foam lining 5a and magnets 4.
[1596] The magnets are magnetized in the radial direction and
mounted longitudinally with a cement that extends the bond beyond
tangent contact. An alternative stent-jacket (not shown) consists
of a short length of thin tubing made of magnetizable stainless
steel, for example. This is slit along one side and magnetized
normal to the long axis. When the elasticity required calls for
tubing too thin and/or not sufficiently magnetizable to support the
magnetic field strength required, it is given an outer layer of a
polymeric matrix with embedded neodymium iron boron particles prior
to magnetization. The addition of a second such outer layer to
serve as radiation shield for use with radiation-emitting stays or
miniballs must likewise not detract from compliance as primary.
[1597] Ferromagnetic stays relate to the stent-jacket just as do
miniball type implants but are inserted from outside the ductus
allowing the lumen to be avoided during and following stenting, so
that in direct stenting without antecedent atherectomy or
angioplasty, the lumen is avoided entirely with stenting sustained
by extraluminal components. An alternative stent-jacket consists of
a length of thin intrinsically magnetized spring stainless steel
tubing as addressed below in the section entitled Stent-jackets and
Stent-jacket Supportng Elements. To allow flexibility, longer
stent-jackets, whether polymeric with tiny permanent magnets
mounted about the outer surface, or metal, consist of a series of
elastic tubes joined or articulated by Palmaz-Schatz-type
connections, as described below under the section entitled
Sectional, or Chain-stents, Segmented and Articulated. Such a
stent-jacket can be made to any length.
[1598] Ordinarily; the magnets are equal in strength and positioned
uniformly about the base-tube; however, the strength of the magnets
or magnetization over an affected area can be keyed to the
subjacent condition, and for eccentric lesions, only those areas
superjacent to the unaffected or affected area of the ductus need
be subjected to tractive force to be drawn outwards. The magnetic
field strength is strong enough to urge the adventitia 2 into
contact with it but not to significantly interfere with the smooth
muscle action in the ductus wall 7. The different kinds of
stent-jacket are described above in the section entitled Types of
Stent-jacket. The stent-jacket base-tube 5 is pliant and slit 9
longitudinally along one side but not so pliant that the lumen 8
can revert to its former stenosed or constricted condition.
[1599] The object is not merely to reinstate passability through
the lumen of the air, blood, food, urine or other substance that is
obstructed, but to do so with the least trauma essential to obtain
results that will not pose complications over a longer term than
does conventional or endoluminal stenting. A basically cylindrical
conformation can be flared. Branches and bends are conformed to
with chain-stents. To allow compliance to the pulse or intrinsic
motility of the ductus and to avert the inducement of atheromatous
lesioning by constriction of the microvessels and nerves of the
adventita, base-tube 5 of stent-jacket 6, described below, is slit,
or if more clearance is needed, then slotted, and perforated.
[1600] The essential compliance will almost always be achieved with
elastomeric or metal tubing of appropriate flexibility, thickness,
and perforation pattern, but can also use compound or plied tubing
of different materials or a compound extrusion, or coextrusion.
Unless the tissue is severely malacotic or sclerotic, the number
and distribution pattern of the magnets mounted about the
stent-jacket is adapted to attract the intravascular miniballs or
stays in a uniform manner. When a spring metal stent-jacket with
intrinsic magnetization as will be described is used, such openings
are likewise necessary. Perforation of the base-tube other than to
adjust its restorative force, such as to allow the adventitia to
`breathe,` engage in ion exchange, and allow tissue infiltration to
avert migration, when more extensive, will reduce its restorative
force, which must not require a thickness that with magnets
unacceptably encroaches upon the adjacent tissue.
[1601] Base tubes may comprise a polymeric tube to the surface of
which have been fastened permanent bar magnets or smaller encased
electromagnets. Smaller thickness, of value where any protrusion
abaxially from the long central axis of the base tube would
encroach upon and press or rub against neighboring tissue is
obtained through use of a base tube comprising a thin magnetizable
metal, for example, magnetized perpendicularly to the long axis of
the substrate ductus. Base-tube perforations are usually open. By
serving as a matrix or scaffold for infiltration by the surrounding
tissue, absorbable adhesives and protein solders can be used for
migration resisting adhesion followed by tissue integration.
[1602] These methods are capable of bolstering fixation
periadventitially, and contact permitting, at the outer surface of
the stent-jacket. Side-straps, described below in the sections
entitled Jacket End-ties and Side-straps, The Extraductal Component
of the Extraluminal Stent and the Means for its Insertion and Gross
Positional Stabilization (Immobilizaton) of the Implant Insertion
Site, allow adjustment in the cinching tautness of the jacket.
End-ties, described below in the section entitled Jacket end-ties
and Side-straps substantially eliminate the chance of migration,
even should the stent take a direct blow.
[1603] Miniballs and stays likewise have external treatments to
encourage integration into the surrounding tissue. For these
subadventitially (perimedially) placed implants to become dislodged
and enter the lumen before becoming integrated into the surrounding
tissue is, based on this position, improbable. When such is a
concern, an impasse-jacket, addressed above in the section entitled
Concept of the Impasse-jacket and below in the section entitled
Miniball and Ferrojluid-borne Particle-impassable Jackets, or
Impasse-jackets, prepositioned downstream will stop and retain any
miniballs indefinitely. Notwithstanding, any miniballs that do
become trapped in an impasse-jacket can be noninvasively extracted
at a later date if desired, as explained in the same sections.
[1604] The primary purpose of impasse-jackets, which applies to an
extent to stent-jackets, magnet-jackets, and patch-magnets,
however, is small-scale drug targeting a certain segment of a
ductus or an organ. Unmagnetized base-tubes and spandex
wrap-surrounds can be used, for example, to reduce an aneurysm
incidentally diagnosed during imaging while still incipient but
confirmed enlarging. When reducible thus, the shear forces within
the weakened segment are restored to the essentially normal, and
the jacket expands and contracts with the pulse. The restorative
force used to contract the weakened artery to a smaller diameter is
intrinsic in the materials of the base-tube, which can, however, be
modified by incorporating perforations for `breathing` or a
mechanical or medication retaining texture embossed on the internal
surface. The elastic side-straps used to prevent migration can be
tightened to adjust jacket compliance.
[1605] Such base-tubes differ are made to a prescribed elasticity
or resilience for compliance with the pulse or smooth muscle action
and in incorporating apertures and a moisture barrier-coated
viscoelastic polyurethane foam lining. To achieve the desired
restorative force within the desired dimensions, selection of the
base-tube material on the basis of intrinsic elasticity and
resilience must therefore consider the most effective internal
surface conformation, which may include undercuts, etching, or
deeper texture for increased bonding surface area of an expansion
insert, texturing or embossing for tissue infiltration and
integration, perforations for gas exchange or breathing, for better
adhesion of a surface film of medication, adhesive, perforation
sealant, and so on, as described below.
[1606] In stent-jackets intended for noninvasive heating to reverse
postprocedural reocclusion due to hyperlasia by means of
noninvasive thermoplasty, the number, size, and distribution of
`breathing` holes as a source of resistance to eddy currents is
compensated for when the temrperature is noninvasively measured by
means of an equivalent temperature calibrated eddy current
detector. Stent-jackets placed before initiating discharge in order
to avoid the risk of a perforation can be conventional or as
addressed below in the section entitled Double-wedge Stent and
Shield-jacket Rebound-directing Linings, but whose presence risks
miniball rebound into the lumen, are made with a softer
stent-jacket internal surface layer that is textured to serve the
purposes indicated, and is backed by a flat-faced layer of greater
resilience which is inclined distoradially to direct rebounds
subadventitially or medially to remain functional for stenting and
thus away from the lumen and toward a functional subadventitial or
medial location for stenting purposes.
[1607] More specifically, as seen in FIG. 10, a miniball discharged
through error at an exit velocity significantly greater than the
results of the testing method provided in the section below
entitled Testing and Tests indicates will perforate through the
ductus wall, become embedded, and trapped within the foam lining.
However, as in FIG. 11, at less excessive levels of momentum, the
miniball can drive the wall of the ductus into the foam lining
compressing it against the more resilient internal surface of the
stent-jacket without perforating it. In that case, it is likely to
rebound at the equal but opposite angle into the lumen.
[1608] For the exit velocity to have been set so erroneously high
that the miniball having perforated the ductus wall and entered the
foam lining would have sufficient remaining momentum to rebound off
the internal surface of the base-tube and then reperforate the
ductus wall in the opposite direction and then rebound into the
lumen is essentially impossible with nonmetal base-tubes and
improbable even with metal ones; few if any miniballs are entirely
metal; coatings of medication, and other therapeutic substances
usually impart a softer, less resilient surface. A double-wedge
lining as shown in FIG. 12 is intended steer the rebounding
miniball away from the lumen and thereby preserve the functionality
of a miniball that drives the ductus wall against the internal
surface of the base-tube. The double-wedge lining accomplishes this
by redirecting the miniball to a point farther down but still
within the ductus wall and jacket.
[1609] In the circulatory system, a powerful extracorporeal
electromagnet and/or an impasse-jacket is always prepositioned
downstream to trap any miniball that might enter the circulation.
In a double-wedge stent-jacket, a more resilient layer, which
becomes thinner moving distad, is placed subjacent (outside,
lateral, centrifugal) to its superjacent (inner) softer layer,
which becomes thicker moving distad, so that these layers together
constitute one continuous layer of which these halves are
complementary to form a layer of uniform thickness. In a
nonsubminiature or readily manipulable size, the inner layer would
seem relatively `hard.` A miniball rebounded off of the distally
receding harder backing layer thus does so at an angle that is more
acute in relation to the central axis of the lumen than were the
reflecting surface parallel to the axis. The prepositioning of a
stent-jacket solely to insulate a site for thermal angioplasty is
unnecessary, and necessitates access to the treatment site through
a second incision at the treatment site, needlessly increasing the
procedural time.
[1610] A miniball that strikes the more resilient layer through the
softer layer and rebounds at the equal and opposite angle will now
be directed abaxially in relation to the angle that would have
resulted were the surface rebounded off of parallel to the central
axis of the lumen. When the area to be treated is extended, an
extraluminal stent-jacket consisting of a train of sections
connected by Palmaz-Schatz type stent connections, for example, can
be made in any length. When the condition varies along the length,
the individual sub-stents are varied accordingly. While
intrinsically magnetized and thin neodymium magnets make possible
extraluminal stents that encroach on neighboring structures
minimally if at all, when perivascular placement should be avoided,
an alternative to a surrounding stent-jacket is the magnet-wrap, or
wrap-surround. A magnet-wrap is placed about a neighboring
structure with magnets or if sufficiently proximate, intrinsic
magnetization directed toward the miniballs or stays within the
target ductus.
[1611] Application thus will usually respond to a need for radially
asymmetrical or eccentric retraction of the ductus wall as in
tracheal collapse, for example. However, both stent-jackets and
magnet-wraps can be prepared to treat the ductus wall whether the
condition is symmetrical or asymmetrical. A clasp-wrap
(clasp-jacket, wrap-surround), addressed below in the section of
like title, is in effect an artificial adventitia or fibrosa with
ferromagnetic clasps for placement about a ductus that lacks an
outer layer of sufficient intrinsic strength to retain implanted
miniballs or stays under even a mild tractive force. Small opposing
clasps, which may be coated with cyanoacrylate cement, mounted to a
wrap made of spandex secured with hook and loop side-straps, for
example, are used both to anchor the wrap into the outer surface of
the ductus and substitute for the intravascular component of the
extraluminal stent. The clasps are usually much more closely spaced
together than are miniballs or stays, but can be asymmetrically to
accommodate an asymmetrical condition.
[1612] When even this distribution would fail to prevent the mild
tractive force from pulling the clasp-wrap away from the
adventitia, a bonding agent that includes cyanoacrylate cement and
is formulated to encourage tissue infiltration is applied to the
internal surface of the wrap, thereby avoiding the need for a
preliminary procedure to place the jacket and wait for integration
to develop. The use of a clasp-wrap is also applicable when the
diameter of the ductus makes the use of miniballs or stays too
difficult. As does insertion by anastomosis of a graft, a
clasp-wrap necessitates local access, but is applied much more
quickly and with less trauma. Avoiding the risks of a graft and
involving no entry as could leak or introduction of a foreign
object into the lumen as would accumulate accreted matter, the use
of a clasp-wrap or compound clasp-wrap with branches should be
considered even when these alternatives are not
contraindicated.
[1613] Just as miniballs and stays, a clasp-wrap can be used with
either an immediately circumvascular stent-jacket, usually for
all-around or almost all-around retraction, or with a magnet-wrap,
usually for retraction from a distance of an arc of a stenotic or
collapsed vessel or duct when intervening tissue in abuting
relation to that to be drawn interferes with the placement of a
stent-jacket, A stent-jacket can also accommodate asymmetrical or
eccentric retraction and is indicated to prevent vasospasm, which
demands circumferential retention. Magnetic force is able to
retract and fixate ductus and tissues as not to encroach on
neighboring tissue, for example, through intervening structures and
along lines and over distances that suture cannot traverse.
[1614] A stent-jacket limits the radially outward excursion of the
miniballs due to the magnetic or patenting force, hence, the
resultant expansion or dilatation of the ductus due to this force,
eliminating any risk of stretching injury. The stent-jacket is also
elastic to accommodate the expansion and contraction of the ductus.
A more resilient stent-jacket to limit expansion is readily
producible but exceptional. If the tractive force is too great,
either will pull through subadventital or subfibrosal implants or
avulse (pull away) a clasp-jacket causing the stent to fail.
Patch-magnets placed subcutaneously or suprapleurally, as described
below in the section entitled Subcutaneous, Suprapleural, and Other
Organ-attachable Clasp- or Patch-magnets can also be used for
eccentric or arcuate retraction.
[1615] Once tissue alongside the sagging dorsal membrane (ligament)
of the collapsed trachea in a small dog, for example, has been
implanted with miniballs clear of the recurrent laryngeal nerves,
the membrane can be lifted out of the lumen, alleviating the
obstruction. This can be accomplished by magnets in a stent-jacket
immediately surrounding the trachea, or situated along longitudinal
ventrolateral lines of a magnet-wrap surrounding the esophagus, or
placed subcutaneously along the neck and shoulders, or
suprapleurally above the ceiling of a collapsed bronchus.
[1616] Where dysphagia is less of a risk, magnetized miniballs can
be implanted along longitudinal ventrolateral lines within the
esophagus itself. This variability in the components expedites
treatment of tracheal segments both above and below the thoracic
inlet. One example of the combined use of these variants is the
application of jointed (articulated or segmented) stent-jackets to
support the dorsal membrane of the trachea anterior to the thoracic
inlet with subcutaneously or suprapleurally placed magnets used to
support the ceiling when collapse extends into the bronchi where
these are embedded in lung tissue and no longer encircleable by a
stent-jacket.
[1617] I. Stent-Jackets and Stent-Jacket Supportng Elements
[1618] I1. General Considerations to Include Insertion
[1619] Stent-jackets are placed in encircling relation to ductus
with the aid of stay insertion hand tools, as addressed below in
the section entitled Stent-jacket Insertion Tools. Stent-jackets
and impasse-jackets, as addressed below in the sections entitled
Concept of the Impasse-jacket and Miniball and Ferrofluid-borne
Particle-impassable-jackets, or Impasse-jackets overlap in
function, but only an impasse-jacket is devised to allow the
extraction of a miniball it has suspended within the lumen by means
of an external electromagnet, for example. The extraductal or
extravascular component, the stent-jacket, consists of a sleeve of
resilient tubing that is slit along one side and when not
magnetized intrinsically, by coating, or lamination, has tiny
permanent magnets,currently made of neodymium iron boron
lanthanoid, mounted about its outer surface. Temporary
shield-jackets and stent-jackets are placed with the aid of a
stent-jacket expansion or insertion tool, addressed below in the
section of like title.
[1620] The tool is made with side-slit edge-engaging (hooking,
working) ends for jackets of a certain thickness; the lining
continues to the edge of the side-slit or side-slot, so that the
jacket does not provide unlined edges or segments along the edges
to accommodate an insertion tool with edge-engaging ends of one and
the same size. In an extraluminal stent that is also to allow the
extraction from the blood, for example, of magnetically susceptible
drug carrier nanoparticles, for example, to achieve the tractive
force required, the magnets will generally be somewhat larger. The
magnets, which will normally consist of toxic neodymium lanthanoid,
are first encapsulated for chemical isolation and cushioning with a
coating of a plastisol-like or rubbery polymer or copolymer, then
marked, usually by means of vapor deposition or sputtering, with an
imaging marker, such as tantalum, tungsten, gold, molybdenum, and
alloys thereof, or a biostable biocompatible radiopaque
polymer.
[1621] The stent-jacket is introduced through a small incision and
placed about the vessel or duct in encircling (perivascular,
circumvascular) relation. The (intravascular) component of the
stent consists of subadventitially or perimedially placed spherule
or stay implants. The magnets mounted about the outer surface of a
magnetic stent-jacket exert the minimum static centrifugal
(circumferentially outward) magnetic retractive force on the
intraductal (intravascular, ductus-intramural) component necessary
to draw the adventitia of the ductus at its quiescent (resting,
end-diastolic, unexpanded, smallest) outer diameter up against the
inner surface of the stent-jacket, which is cushioned with a
moisture barrier-coated viscoelastic polyurethane foam lining to
minimize injury to any perivascular vessels and nerves.
[1622] The elastic and side-slit stent-jacket thus poses little
resistance to the vasotonic and pulsatile expansion and contraction
of arteries or the transit of the contractive waves of peristalsis.
When the sole object is to preserve patency, the stent-jacket is
fitted to the ductus so that the surface of the moisture
barrier-coated viscoelastic polyurethane foam lining is maintained
flush to the adventitia under the least effective force of
attraction by the magnets surrounding the base-tube, the
adventitial blood and nervous supplies impressed within the
moisture barrier-coated viscoelastic polyurethane foam. Providing
the highest energy product currently available, such magnets
deliver adequate ductus wall retractive force in tiny sizes that
suitably shaped and chemically isolated by encapsulation cause
little if any irritation to neighboring tissue.
[1623] For use with arteries, a polymeric base-tube with magnets
mounted about its outer surface can sometimes be replaced with a
tube of thin sheet stock stainless steel that is intrinsically
magnetized normal (radially in relation to) its long axis and slit
to allow compliance with the pulse. Various strategies for building
up the tractive force of the tube through the application of
coatings that incorporate lanthanoid to allow the tube to remain
thin for elasticity are addressed below in the section entitled
Stent-jackets and Stent-jacket Supportng Elements. However, in a
peristaltic ductus, the retractive force must be small enough and
the stent-jacket base-tube pliant enough to pose minimal resistance
to the inward excursion of the traveling contractive wave, which is
usually more powerful than the stenosis or constriction produced by
a disease without or following surgical treatment.
[1624] The internal diameter of the stent-jacket is matched to the
external diameter of the ductus when quiescent, so that this
retraction restores luminal patency. Intrinsic motility in the
esophagus is not simply inward but involves the squeezing downward
by the traveling wave of contraction of larger boli that produce an
outward bulging of the esophagus just ahead of (addressed below)
the contractive wave. The action travels down the organ as a
circumferential expansion followed by a contraction. Irritation
free conformity to this continuous action is elusive to any means
of mechanical compliance or tracking; however, in the esophagus,
the action occurs only during deglutition (swallowing). Lower in
the tract, compliance is difficult due to the absolute excursion
rather than the more clearly defined character of the action.
[1625] Compliance with this action without resistance as would
induce dysphagia demands a long fatigue life thin walled polymeric
base-tube with elasticity in the long dimension such as of an open
mesh polyester reinforcing braid incorporated within the walls of
silicone tubing as produced by NewAge Industries, Southampton, Pa.
or Aesthetic and Reconstructive Technologies, Reno, Nev., for
example, or of tubing made of a nickel titanium rings attached by
longitudinal elastic ribs of plastic, for example, fastened about a
tube of elastic polyester or polyurethane-polyurea copolymer
spandex (Elastane.RTM. Lycra.RTM.), for example (see for example,
Watanabe, M., Sekine, K., Hori, Y., Shiraishi, Y., Maeda, T.,
Honma, D., Miyata, G., Saijo, Y., and Yambe, T. 2005. "Artificial
Esophagus with Peristaltic Movement," Journal of the American
Society for Artificial Internal Organs 51(2): 158-161), magnets
with longitudinal extension as does not interfere with this
flexion, and application of the optimal magnet strength to maintain
the retractive force required.
[1626] The noncollapsible, flexible, and side-slitted
circumvascular stent-jacket limits closure of the substrate vas or
ductus to the smallest normal diameter while allowing the ductus to
expand. More specifically, the descending bulge and contraction of
the esophagus during swallowing can be conformed to by a
stent-jacket in the form of reach-around arms (ribs, tracheal
cartilages) consisting of incomplete rings or broken bands of
magnetized spring steel encapsulated for chemical inertness or
magnetizable spring stainless steel, for example connected by a
narrow spine located diametrically opposite to the aligned breaks
in the rings. To allow optimal flexibility of the reach-around
arms, the spine is kept proportionally narrow.
[1627] Expansion of the stent-jacket to position it about the
esophagus requires that the breaks in the bands, that is, the space
separating the free edges at the ends of the ribs, or side-slots,
be aligned, and to preclude migration and present as a unit for
expeditious placement, the bands must be longitudinally connected.
Any rounding contour will interfere with band flexibility. The
bands are therefore ground smooth at the edges. The appliance can
be rotated to treat an eccentric lesion or made as long as
necessary. Whether inserted by means of a stay insertion tool or
barrel-assembly, the ductus-intramural implants are prepositioned
to match the fitting of the appliance to the lesion.
[1628] When a bolus passes, the changes in distance between
adjacent edges of neighboring bands increases as the free ends of
the side-slots are approached, and is reduced as the spine is
approached. The spine is therefore made as flexible in the
longitudinal direction as possible, but will define the center of
the least compliant arc. The circumferential positioning of the
spine, whether it and the portions of the spines beside it are
magnetized and the subjacent substrate ductus is implanted in
radial alignment thereto depends upon the amenability or tolerance
of the lesioned tissue to such treatment. When the lesion is
eccentric (radially asymmetrical), the spine and adjacent portions
of the ribs will therefore not mount magnets, have been
intrinsically magnetized, or overly implanted tissue, and will be
positioned diametrically opposite to the lesion.
[1629] When reduced compliance along the spine is not a problem and
some retractive force is desirable to maintain luminal patency, the
spine is made sufficiently magnetic for this purpose. Such a
stent-jacket is suitable for stenting other portions of the
gastrointestinal tract, for example. Accordingly, the breaks, or
side-slots, in the thin-stock bands are situated diametrically
opposite to the spine and are large enough to allow the bands to
contract with the esophagus as the descending wave propels the
bolus downward passes. The bands likewise pose little resistance to
expansion by a large bolus and resumption of the quiescent
diameter.
[1630] When the bands cannot be intrinsically magnetized to exert
sufficient tractive force sufficient to maintain luminal patency
and contract with the intrinsic action, small permanent magnets are
mounted about the outer surface of each band in radial alignment to
the ductus-intramurally implanted miniballs or stays. The elastic
stent-jacket thus complies with pulsatile, tonic, or peristaltic
expansion and allows the discretionary treatment of eccentric
lesions. When the ductus is enlarged or swollen, a stent-jacket is
chosen that incorporates an absorbable or percutaeous ultrasonic
lithotriptor-destructible expansion insert. Expansion inserts are
addressed below in the section entitled Expansion Inserts
Absorbable, Meltable, and Comminutable for Time-discrete
Decremental Contraction of Stent-Jackets.
[1631] An expansion insert glued along one side of the side slit so
that the stent-jacket can still comply as slightly expanded allows
the stent-jacket to contract in step with subsidence (regression,
resolution) in the enlarged (dilated, distended, swollen, or
ectasic) ductus. The advent of endoscopic means to minimize the
trauma of exposure significantly augments the practicability and
preferability of circumvascular over endoluminal stents in many
locations and treatment situations. Access to the coronary
arteries, for example, no longer necessitates a median sternotomy
(midsternal thoracotomy, "zipper" incision), clamshell,
anterolateral, or hemiclamshell thoracotomy. In the chest, remotely
controlled robotic means materially advance the capability to
minimize the access portal through a ministerotomy.
[1632] Access to the external surface of a coronary artery is
usually direct through the divided sternum but can be accomplished
with a craniotome or trephine. When possible, a minimal incision
thoracotomy, such as is used in minimally invasive direct coronary
artery bypass (MIDCAB; limited access coronary artery bypass;
`keyhole` incision heart surgery) to expose the left anterior
descending artery and its diagonal branches on the front of the
heart, is performed. Robotically assisted coronary artery bypass
(RACAB) allows access to the coronary arteries without the need for
a midsternal thoracotomy that would increase trauma and healing
time. For endoscopic and robotic technology to allow the placement
of a stent-jacket, magnet-surround, or miniball-surround requires
configuration of the insertion tool for such use.
[1633] Retention of the wall of the ductus by means of
subadventitial implants peripheral to the more vital tissue of the
lumen lining under minimal retractive force averts compression
necrosis and fistulization; subjected to strong mechanical forces,
fibrous connective tissue substantially omits living cells. The
extraluminal stent accomplishes this while leaving the lumen free
and clear of any foreign object. The risks of necrosis and
fistulization rise in proportion to an increase in adluminal
placement, prompting means such as the application of an adhesive
to prevent delamination within the lumen wall. The unobstructed and
object free lumen is less likely to restenose, and should
reintervention become necessary, the lumen will not be obstructed
by a stent. The catheter-based apparatus described may be used with
the patient inside the tunnel (gantry, bore) of a tomograph.
[1634] In structure, function, and application, the extraluminal
stents to be described herein are fundamentally different from the
various cuffs and sheaths to which such terminology has been
applied in the past (see, for example, Zou, R. J., Zou, L. J.,
Huang, S. D., Wang, Y., Han, L., Ji, G. Y., and Xu, Z. Y. 2007.
"Effect of External Stents on Prevention of Intimal Hyperplasia in
a Canine Vein Graft Model," Chinese Medical Journal (in English)
120(24):2264-2267; Izzat, M. B., Teng, Z. Z., Ji, G. Y., Chu, H.
J., Li, Z. Y., Zou, L. J., Xu, Z. Y., and Huang, S. D. 2007. "Does
PGA External Stenting Reduce Compliance Mismatch in Venous
Grafts?," Biomedical Engineering Online 6:12; Jeremy et al. 2004
cited above; Izzat et al. 1996 cited above; Froehlich, P., Seid, A.
B., Kearns, D. B., Pransky, S. M., and Morgon, A. 1995. "Use of
Costal Cartilage Graft as External Stent for Repair of Major
Suprastomal Collapse Complicating Pediatric Tracheotomy,"
Laryngoscope 105(7 Part 1):774-775).
[1635] Compression of the microvasculature and tiny nerves that
supply the outer tunics, or vasa and nervi vasora, is minimized by
lining the stent-jacket with biocompatible padding in the form of a
viscoelastic polyurethane foam (moisture barrier-coated
viscoelastic polyurethane foam). Necrosis is also minimized by the
tiny size of the intraductal implants, such that the immune system
is able to eliminate the consequences of cells crushed during
implantation or by mechanical stress. The size and mass of the
magnets used in stent-jackets, magnet-wraps, and patch-magnets is
minimized through the use of high energy product sintered neodymium
iron boron (Nd.sub.2Fe.sub.14B; NIB; NdFeB, or "neo") magnets. Such
magnets are commonly available with a plating of nickel and outer
plating of gold.
[1636] With sufficient compliance to accommodate normal (tonic,
pulsatile, or peristaltic) changes in caliber, a stent-jacket sized
for the normal diameter of an artery will also contain and adjust
to the reduction in ductus diameter of an incipient aneurysm as the
aneurysm heals and subsides (shrinks, subsides resolves,
regresses). A jacket without magnets or intraductal implants can be
used to contain an incipient aneurysm before a more advanced
fusiformation or sacculation that if left untreated would become
lined with a laminar thrombus, or to shield against the striking of
neighboring tissue by a miniball that perforates when discharged,
for example. Unlike a noncompliant external stent of the prior art
that must be secured with sutures at points over its entire
surface, the stent-jacket is secured by means of elastic
side-straps that do not add to the length of the small laparoscopic
entry portal required for insertion. If the ductus to be stented is
curved or must flex, a sectional or chain-stent, that is, one
segmented or articulated is used.
[1637] By definition, an incipient aneurysm poses no risk of
obstruction due to involution (infolding) or rupture when reduced
by the stent-jacket, which can therefore include perforations or
breathing holes to allow access to the outer surface of the artery,
often the aorta. Even though circumvascular placement averts
numerous drawbacks to endoluminal placement, in the case of an
aneurysm, unless diagnosed before progressed to the point that
placement is difficult if not dangerous, the use of an extraductal
stent is to be avoided. Unlike an endoluminal stent-graft, use of a
circumvascular stent to contain an aneurysmal artery becomes more
difficult, less feasible, and less effective as the condition
progresses. The larger the diameter of the aneurysm, the more
difficult is opening a stent-jacket of suitable diameter to
surround it, and the greater the risk of rupture, as well as the
risk of reducing a thrombus within that could result in complete
obstruction and the liberation of embolizing debris.
[1638] If there is no accumulation within, then the wall becomes
too slack and subject to obstructive infolding if reduced from
without. Whether the result of a fistula, accidental perforation,
or incision, surgical repair and not a stent-jacket is used to seal
a leaking ductus. Application of an external jacket without an
intraductal component is addressed in the section above entitled
Stent-jackets Used with Miniballs, this section, and the sections
to follow entitled Means for Inducing the Formation of a Strong
Implant-Tissue Bond, Description of the Preferred Embodiments,
Expansion Inserts Absorbable, Meltable, and Comminutable for
Time-discrete Decremental Contraction of Stent-Jackets, and
Alternative Procedure to the Use of Expansion Inserts.
[1639] However, if initially sized to accommodate autonomic
expansion in an already enlarged condition, then following
subsidence, the end internal diameter of the stent-jacket will
remain too large. The stent-jacket should not remain larger in
internal diameter than the outer diameter in its resting phase of
the ductus once healed. When the aneurysm is larger within the
healable range, a stent-jacket with an expansion insert, as
addressed below in the section entitled Expansion Inserts
Absorbable, Meltable, and Comminutable for Time-discrete
Decremental Contraction of Stent-Jackets, is used. With such an
insert, the initial diameter of the stent-jacket accommodates the
ductus and gradually contracts with the ductus to its end diameter.
The use of a larger stent-jacket that would leave the stent-jacket
slightly oversized once healing is complete is not preferred.
[1640] When the ending diameter of the ductus exceeds that expected
by not more than 20 percent, the lack of full encirclement exerts a
negligible effect on the ability of the stent to comply with the
movement intrinsic in the ductus. If end-ties for preventing
migration, as will be described, are contraindicated, but
sufficient lengths of healthy tissue extend beyond the ends of an
affected segment, then bridging or overextension of the
stent-jacket or articulated stent-jacket onto the healthy tissue
allows magnets and implants to be used over such nonaneurysmal or
otherwise unaffected segments, and in contrast to an endoluminal
stent used in a similar way, without encroachment upon the
physiologically more active inner layers of the vessel. The use of
a chain-stent, as addressed below in the section entitled
Sectional, or Chain-stents, Segmented and Articulated, is
indicated.
[1641] If the quiescent diameter of the ductus following healing
might exceed the normal by more than 20 percent, an expansion
insert that is spontaneously absorbed and/or can be actively
reduced at a controlled rate over the period predicted for
subsidence is used. This adaptability in diameter obviates the need
to choose between a stent-jacket that fits initially but will be
too small or too large following subsidence. Enclosing the vessel
or duct within a compliant mantle that retracts the wall round and
about both maintains the lumen patent and restrains the ductus from
outward collapse or rupture. An extraluminal stent can therefore be
used for structural failure whether inward or outward, and supports
the wall during expansion and contraction with either. When
significant, accurate placement of the miniballs requires that
discharge be timed to the pulse. The momentum of discharge negates
any resistance to penetration by the small infoldings or pleats
that line the lumen on contraction.
[1642] When an additional object is to use the stent-jacket for
followup magnetic drug-targeting, the magnetic force of the magnets
about the base-tube is increased to the level necessary to attract
the magnetically susceptible ferrobound particles passing through
the bloodstream, usually injected in the form of a ferrofluid.
Concerns about tunical delamination warrant testing as addressed
below in the section entitled In Situ Test on Endoluminal Approach
for Intra- or Inter-laminar Separation (Delamination, Laminar
Avulsion). Delamination propensity testing and countermeasures
addressed in the sections below entitled Use of Solid Protein
Solders and Stays Coated with a Solid Protein Solder Coating and
Cyanoacrylate Cement among others have been devised for application
at the time of implantation to obviate the need for reentry.
[1643] When the drug or drugs are most effectively delivered to the
treatment site at a concentration too high for systemic dispersal,
the stent-jacket is provided with magnets strong enough to also
support drug-targeting. A degenerative condition that would bode
delamination at a later date if left untreated generally warrants
the use of medication and/or brachytherapeutic implants with this
capability. Only in situ testing will allow the strength of
magnetization that would not pull through or cause
delamination.
[1644] Should delamination occur, a barrel-assembly with a
muzzle-head that is magnetically susceptible for steering, as
addressed in the section below entitled Use of an External
Electromagnet to Assist in Steering or in Freeing the Muzzle-head,
and/or equipped with push-arm radial projection units, as addressed
below in the section entitled Push-arm Radial Projection Unit
Tool-inserts, or a radial projection catheter similarly equipped,
as addressed in the section below entitled Radial Projection
Catheters, is used to push the lumen wall radialliy outward after
the same apparatus has been used to inject a cement into the
delamination interface. If prepositioned, the stent-jacket can be
used to back up the wall brought flush against the base-tube lining
to compress the separated layers.
[1645] When the ductus expands during systoles or peristalsis and
contracts during the passage of peristaltic waves, the
microvasculature and innervation are accommodated within the
moisture barrier-coated viscoelastic polyurethane foam lining and
by the flexibility of the base-tube. The thickness of the lining is
selected to minimize if not eliminate the long-term restriction or
compression associated with expansion. This action demands a
base-tube material capable of constant flexion in the internal
environment with no significant loss in pliancy. Materials
currently available that allow this are specified in the section
below entitled Internal Environment-resistant Base-tube Polymers,
Metals, and Combinations Thereof.
[1646] While not a direct object of the present invention, recent
research indicates that a static magnetic field, previously thought
to be completely noninteractive with tissue, reduces inflammation
(see Morris, C. E. and Skalak, T. C. 2008. "Acute Exposure to a
Moderate Strength Static Magnetic Field Reduces Edema Formation in
Rats," American Journal of Physiology. Heart and Circulatory
Physiology 294(1):H50-H57; Morris, C. E. and Skalak, T. C. 2007.
"Chronic Static Magnetic Field Exposure Alters Microvessel
Enlargement Resulting from Surgical Intervention," Journal of
Applied Physiology 103(2):629-636; Morris, C. E. and Skalak, T. C.
2005. "Static Magnetic Fields Alter Arteriolar Tone in Vivo,"
Bioelectromagnetics 26(1): 1-9).
[1647] It has been asserted that subjection to a static magnetic
field reduces vasotonicity (see Gmitrov, J. 2013. "Static Magnetic
Field Effect on Microcirculation, Direct Versus Baroreflex-mediated
Approach," Electromagnetic Biology and Medicine 32(4):448-462;
Albuquerque, W. W., Costa, R. M., Fernandes Tde, S., and Porto, A.
L. 2016. "Evidences of the Static Magnetic Field Influence on
Cellular Systems," Progress in Biophysics and Molecular Biology
121(1):16-28; Gmitrov, J. 2010. "Static Magnetic Field Blood
Pressure Buffering, Baroreflex vs. Vascular Blood Pressure Control
Mechanism," International Journal of Radiation Biology
86(2):89-101; Gmitrov, J. 2007. "Static Magnetic Field Effect on
the Arterial Baroreflex-mediated Control of Microcirculation:
Implications for Cardiovascular Effects Due to Environmental
Magnetic Fields," Radiation and Environmental Biophysics
46(3):281-290; Gmitrov, J. 2007. "Geomagnetic Field Modulates
Artificial Static Magnetic Field Effect on Arterial Baroreflex and
on Microcirculation," International Journal of Biometeorology
51(4):335-345; Gmitrov, J., Ohkubo, C., and Okano, H. 2002. "Effect
of 0.25 T Static Magnetic Field on Microcirculation in Rabbits,"
Bioelectromagnetics 23(3):224-229; Gmitrov, J., Ivanco, I., and
Gmitrova, A. 1990. "Magnetic Field Effect on Blood Pressure
Regulation," [in English] Physiologia Bohemoslovaca
39(4):327-334).
[1648] The detailed configuration of stent-jackets in dimensions,
width of side-slit or side-slot, positioning about the outer
surface of magnets, and whether the base-tube is sectional or
segmental is keyed to the application. An adavantageous attachment
of the ductus is not dissected but accommodated by being straddled
or spanned over with a side-slot. Eliminating ductus-intramural
implants and magnets at the attachment not only preserves the
attachment but averts the risk of erosive injury or fistula
generative irritation to the tissue at and about the attachment.
The side-slot is not targeted and not a likely area for a
perforation. A stent-jacket that does not accommodate an attachment
fully encircles the substrate ductus and can be provided with
ductus wrap-around hook and loop straps, or side-straps
(belt-straps, straps, side-belts).
[1649] addressed below in the section entitled Gross Positional
Stabilization (Immobilizaton) of the Implant Insertion Site, when a
fast or erratic pulse makes gauging the diastoles difficult, the
stent-jacket, of which the internal diameter should match the outer
diameter of the artery, is prepositioned with side-straps fastened
to prevent the side-slit or side-slot from opening. Temporarily
reducing or eliminating expansion and contraction allows greater
accuracy in placing the implants, and temporarily reducing or
eliminating expansion of the side-slit reduces or eliminates the
risk of perforation therethrough. Following discharge, the straps
are loosened so that the stent-jacket is free to expand with the
artery. Accordingly, the barrel-assembly should allow blood to pass
at the end-diastoles. Despite the measures addressed below in the
section entitled Hypoxia and Ischemia-averting Elements, this
factor will limit the muzzle-head that can be used in outer
diameter.
[1650] End-ties, as addressed below in the section entitled Jacket
end-ties and Side-straps, are end-tethers of suture which are
fastened to the base-tube by sewing or riveted at or near to the
ends of the base-tube. Stent-jackets with nonabsorbable suture
end-ties can be tied around the substrate ductus at or beyond the
sides of the base-tube or sutured to neighboring tissue. With large
ductus, the end-ties can be passed through connecting tissue and
self-attached with the hook and loop fasteners provided. A
side-slot can also be used to blank out a longitudinal arc along a
side of the base-tube that would abut on tissue which should be
avoided. Magnets that despite their minute size, soft outer
coating, and rounded edges arouse concern for encroachmemt upon and
irritation of neighboring tissue are situated aside from the
side-slot.
[1651] This will usually be the case with a coronary artery where
the magnets would abut upon the heart. Following healing and
cessation in the use of platelet blockades in arteries or
anticoagulants in veins, an extraluminal stent is athrombogenic.
Exceptionally, all types of thrombotic accidents warrant
antiplatelet blockade for prevention (Adams, RD., Victor, M., and
Ropper, A. H. 1997. "Cerebrovascular Diseases," Chapter 34, pages
819-821), but anticoagulants rather than platelet blockades are
used with established stoke (Adams, R. D. et al. 1997, op cit.,
page 819; Yatsu, F. M. 1995. "Treatment and Prevention of Stroke,"
in Rowland, L. P. (ed.), Merritt's Textbook of Neurology, Media,
Pa.: Williams and Wilkins, page 273).
[1652] Numerous problems encountered with endoluminal stents are
addressed above in the section entitled Background of the
Invention. 2. Preliminary Description of the Invention. Introduced
from outside the ductus, three types of device to be described,
stays, clasp-wraps, and impasse-jackets, avoid the lumen entirely.
When used in the vascular tree, these avoid the problems associated
with placement of a foreign object in the lumen, disruption to the
flow of blood, and the adverse consequences such disruption can
induce (see, for example, Shive, M. S., Salloum, M. L., and
Anderson, J. M. 2000. "Shear Stress-induced Apoptosis of Adherent
Neutrophils: A Mechanism for Persistence of Cardiovascular Device
Infections," Proceedings of the National Academy of Sciences of the
United States of Amerca 97(12):6710-6715; Shive, M. S., Brodbeck,
W. G., Anderson, J. M. 2002. "Activation of Caspase 3 During Shear
Stress-induced Neutrophil Apoptosis on Biomaterials," Journal of
Biomedical Materials Research 62(2):163-168).
[1653] The ability to stent a ductus without the need to enter the
lumen when using stays eliminates the potential for adverse
sequelae, to include the reduction if not elimination of elastic
recoil, stretching, dissection injury, and the ability to treat and
maintain patent a lumen too tortuous to have been tracked
transluminally. The means to be described for magnetic extraluminal
stenting are equally usable for inserting implants that consist
entirely of medication or irradiating seeds into the wall of any
ductus. The ability to quickly implant one or several drugs and/or
seeds having localized action with little effect on neighboring
tissue can eliminate the need for systemic administration that
would disperse medication throughout the body or extracorporeal
administration that would demand a higher dose.
[1654] Since it compresses the lumen wall from within, tearing
circumferential fibers or crushing any prominences and trapping
debris between the stent and the intima, endoluminal stenting is
more often applicable than is extraluminal stenting to stenting
without first performing an angioplasty. In ballistic implantation,
the muzzle-head could dislodge debris, whereas using stays, the
lumen would not be entered at all. Since imaging cannot be depended
upon to rule out the risk of liberating potentially embolizing
debris, endoluminal stenting in the arterial tree assumes its
previous removal (see the section below entitled Thermal ablation
and angioplasty--(Lumen Wall Priming Searing- or Cautery-) capable
Barrel-assemblies). Neither would insufficiency of intimal-medial
thickness needed to place ductus-intramural implants be suitably
remedied by allowing plaque to remain.
[1655] In this circumstance, the plaque is eliminated and
sufficient wall thickness obtained with the aid of tumefacient
drugs that temporarily cause the lumen wall to swell providing the
needed thickness, or injectable fillers, such as collagen,
hyaluronic acid, a gelatin powder-autologous blood mixture, or fat,
which preserve wall thickness for months, or polycrylamide-water,
viscid silicone oil, polymethylmethacrylate bead-collagen, and
polyalkylimide-water mixtures, which for such application, must be
highly viscous to provide a long term effect. Provided the
ductus-intramural implants have become integrated into the tissue,
that repeated compression on the systoles can eventually disperse
and flatten the injectant is of nugatory consequence. Such
injection is performed with radial projection unit injection
tool-inserts, as addressed below in the section entitled Radial
Projection Unit Tool-Inserts.
[1656] The use of an absorbable endoluminal stent (see, for
example, Bundhun, P. K., Janoo, G., Yanamala, C. M., and Huang, F.
2017. "Adverse Cardiovascular Events Associated with Biodegradable
Polymer Drug-eluting Stents and Durable Polymer Everolimus-eluting
Stents: A Systematic Review and Meta-analysis of 10 Randomized
Controlled Trials," Medicine (Baltimore, Md.) 96(28):e7510;
Bundhun, P. K., Yanamala, C. M., and Huang, W. Q. 2017. "Comparing
Stent Thrombosis Associated with Zotarolimus Eluting Stents Versus
Everolimus Eluting Stents at 1 Year Follow up: A Systematic Review
and Meta-analysis of 6 Randomized Controlled Trials," BioMed
Central Cardiovascular Disorders 17(1):84; Bundhun, P. K., Bhurtu,
A., Pursun, M., Soogund, M. Z. S., Teeluck, A. R., and Huang, W. Q.
2017. "Long-term (2-5 years) Adverse Clinical Outcomes Associated
with ZES [zotarolimus-eluting stents] versus SES [sirolimus-eluting
stents], PES [paclitaxel-eluting stents] and EES
[everolimus-eluting stents]: A Meta-Analysis," Scientific Reports
7(1):6385; Kalra, A., Rehman, H., Khera, S., Thyagarajan, B.,
Bhatt, D. L., Kleiman, N. S., and Yeh, R. W. 2017. "New Generation
Coronary Stents: Current Data and Future Directions," Current
Atherosclerosis Reports 19(3):14; Alraies, M. C., Darmoch, F.,
Tummala, R., and Waksman, R. 2017. "Diagnosis and Management
Challenges of In-stent Restenosis in Coronary Arteries," World
Journal of Cardiology 9(8):640-651; Cui, Y., Liu, Y., Zhao, F.,
Shi, D., and Chen, K. 2016. "Neoatherosclerosis after Drug-Eluting
Stent Implantation: Roles and Mechanisms," Oxidative Medicine and
Cellular Longevity 2016:5924234 (also cited above in the section
entitled Backgrond of the Invention. 2. Preliminary Description of
the Invention); Pandya, B., Gaddam, S., Raza, M., Asti, D., and
Nalluri, N., 2016. "Biodegradable Polymer Stents vs Second
Generation Drug Eluting Stents: A Meta-analysis and Systematic
Review of Randomized Controlled Trials," World Journal of
Cardiology 8(2):240-246; Araki, T., Nakamura, M., and Sugi, K.
2014. "Characterization of In-stent Neointimal Tissue Components
Following Drug-eluting Stent Implantation According to the Phase of
Restenosis Using a 40-MHz Intravascular Ultrasound Imaging System,"
Journal of Cardiology 64(6):423-429; Ramcharitar, S. and Serruys,
P. W. 2008. "Fully Biodegradable Coronary Stents: Progress to
Date," American Journal of Cardiovascular Drugs 8(5):305-314; Di
Mario, C. and Ferrante, G. 2008. "Biodegradable Drug-eluting
Stents: Promises and Pitfalls," Lancet 371(9616):873-874; Ormiston,
J. and Webster, M. 2007. "Absorbable coronary stents," Lancet
369(9576):1839-1840) is not preferred, in part, because this
requires the use of a balloon following withdrawal of the
barrel-assembly.
[1657] In many instances, the use of stays can allow avoiding
luminal entry altogether, which the use of an endoluminal stent
negates. In a patient with atherosclerosis, plaque not already
present is likely to develop at predictable locations, such as at
branches, the carotid a prominent example. Since it will be
absorbed, even if the patient is undergoing treatment in the
catheterization laboratory, a drug-eluting biodegradable or
absorbable stent cannot be placed as a preventive or ameliorative
measure for plaque not yet materialized. The stent might detain or
reduce the inflammation for a time but then disappear, allowing the
progressive blockage to resume unimpeded. To the extent that
dependence for attenuating the disease process is placed upon the
drug eluted from a nonabsorbable stent, only a finite amount of the
drug will be available.
[1658] Broadly, while absorbable stents of magnesium (see, for
example, Waksman, R., Erbel, R., Di Mario, C., Bartunek, J., de
Bruyne, B., and 10 other authors, 2009. "Early- and Long-term
Intraductal Ultrasound and Angiographic Findings after
Bioabsorbable Magnesium Stent Implantation in Human Coronary
Arteries," Journal of the American College of Cardiology:
Cardiovascular Interventions 2(4):312-320) are for this purpose
depleted over a suitable interval, polymer stents (see, for
example, Stinson, J. S. 2001. "Bioabsorbable Self-expanding Stent,"
U.S. Pat. No. 6,245,103) generally do so slowly. A subsidiary
application of the present invention contemplates the use of a
stent-jacket base-tube with end-ties (addressed below) and without
magnets to truncate an incipient aneurysm from further distention.
The incipient aneurysm will not encroach on adjacent structures or
noticeably pulsate.
[1659] Asymptomatic, it must be detected during imaging for an
unrelated purpose or specifically to catch subclinical pathology.
When spontaneous or treated subsidence is improbable, the cost of
repeated tomography or ultrasonography high, the trauma to enter
deemed warranted, and the risk of enlargement high, active
suppression by placement of a stent-jacket must be cosidered
preferable to active surveillance (previously referred to as
`watchful waiting`). In such use, the resilient base-tube can be
inserted and maneuvered into circumvascular position through one or
two relatively small incisions. The quantity of periadventitial or
perivascular fat about the aorta often substantial, only so much
fat is trimmed away as will keep the aorta from being constricted
under the retentive force of the nonmagnetic stent-jacket.
[1660] The availability of less radical procedures encourages
earlier intervention. Placement of a stent-graft, much less
conventional open repair, posing a poor risk to benefit ratio and
the odds for rupture slight so long as the condition has not
advanced, accepted doctrine is that an abdominal aortic aneurysm be
monitored until it attains a diameter of five centimeters or more,
produces discomfort, or enlarges. These can, however, arise at any
time, the need for periodic reexamination is open-ended. A simpler
endoscopic repair allows this abiding concern to be reduced with
reexamination needed only to confirm that the integrity and
placement of the reducing wrap persist. If not detected and treated
earlier, the condition may progress until markedly fusiform or
saccular, in some cases having accumulated a laminated thrombus
lining.
[1661] The thrombus affords no protection against rupture adjacent
to the sac, and once thrombosed, intervention of any kind risks
embolization. FIG. 15 shows a constraint for laparoscopic insertion
that can be placed before a diameter that warrants surgical repair
is attained. Aneurysms do not resolve spontaneously, and except for
an accumulation of thombus that may obstruct rupture, preserve the
rate of flow-through, blood pressure, and luminal diameter
preventing thromboembologenic turbulence, any change will be for
the worse. Worse still, the mortality rate at 10 years following
surgical repair is up to 50 percent (The Merck Manual of Diagnosis
and Therapy, 18th Edition, Section 7, Cardiovascular Disorders,
section 79, "Aneurysms," page 741). For that reason, intervention
in a young patient while the aneurysm is still small enough to be
reduced without serious risk of complications is prudent.
[1662] To reduce the chances for an asymptomatic aneurysm to go
unnoticed, thoracic imaging should specifically check for such a
condition. The jacket must be lined with nonbiodegradable or
bioresistant viscoelastic polyurethane, or moisture barrier-coated
viscoelastic polyurethane foam, and include perforations to expose
the outer tunic to the surrounding gas. A cloth bandage if used to
reduce an incipient aneurysm is critically lacking in that it may
`breath,` but as addressed above in the section entitled
Accommodation of the Adventitial Vasculature, Innervation, and
Perivascular Fat, will induce atherosclerosis quickly if it
constricts supportive microvessels and nerves.
[1663] Early detection and containment with less trauma would
truncate the degenerative process and the risk of rupture. So long
as the enlargement has not spread to the common iliac arteries or
become thrombosed and the available length of aorta superior and
inferior to the aneurysm, or `necks,` `are at least 1.5
centimeters, an elasic base-tube without ductus-intramural
ferromagnetic or magnet implants and including cut-outs to clear
any branches can be maneuvered into position. While limited to
aneurysms diagnosed prior to any significant enlargement, such a
stent-jacket is not limited to an aneurysm in any particular
location, so that an abdomnal aortic aneurysm, for example, need
not be infrarenal. Not a magnetic stent, minimizing the thickness
of the base-tube and magnets to avoid rubbing against the
surrounding tissue is not a factor.
[1664] While the matter remains in dispute as to reintervention,
the realization is increasing that compared to conventional
surgical repair the endovascular treatment of an aneurysm should
commence promptly (Deery, S. E., O'Donnell, T. F. X., Bodewes, T.
C. F., Dalebout, B. A., Pothof, A. B., and 3 others 2018. "Early
Reintervention after Open and Endovascular Abdominal Aortic
Aneurysm Repair is Associated with High Mortality," Journal of
Vascular Surgery 67(2):433-440.el; Qiu, J., Shu, C., Cai, W., Li,
M., and Li, Q. 2017. "Early Intervention Effects of Open Repair and
Endovascular Aortic Repair on Patients Suffering from 40-54 mm
Abdominal Aortic Aneurysms: Single Center Experience," Minerva
Chirurgia 72(5):391-396; Deery, S. E., Soden, P. A., Zettervall, S.
L., Shean, K. E., Bodewes, T. C., and 3 others 2017. "Sex
Differences in Mortality and Morbidity Following Repair of Intact
Abdominal Aortic Aneurysms," Journal of Vascular Surgery
65(4):1006-1013; Ulug, P., Sweeting, M. J., von Allmen, R. S.,
Thompson, S. G., Powell, J. T. and 8 collaborators 2017.
"Morphological Suitability for Endovascular Repair,
Non-intervention Rates, and Operative Mortality in Women and Men
Assessed for Intact Abdominal Aortic Aneurysm Repair: Systematic
Reviews with Meta-analysis," Lancet 389(10088):2482-2491; Canadian
Task Force on Preventive Health Care 2017. "Recommendations on
Screening for Abdominal Aortic Aneurysm in Primary Care," Canadian
Medical Association Journal 189(36):E1137-E1145; Zarins, C. K.,
Crabtree, T., Bloch, D. A., Arko, F. R., Ouriel, K., and White, R.
A. 2006. "Endovascular Aneurysm Repair at 5 Years: Does Aneurysm
Diameter Predict Outcome?," Journal of Vascular Surgery
44(5):920-931; Flores, J., Kunihara, T., Shiiya, N., Yoshimoto, K.,
Matsuzaki, K., and 8 others 2005. "Importance of Early Repair of
Isolated Abdominal Aortic Dissecting Aneurysm," Vasa 34(2):118-122)
a conventional endovascular stent-graft can cause as many problems
as it alleviates (below and see, for example, Rutherford, R. B.
2006. "Randomized EVAR [endovascular aneurysm repair] Trials and
Advent of Level I Evidence: A Paradigm Shift in Management of Large
Abdominal Aortic Aneurysms?," Seminars in Vascular Surgery
19(2):69-74) recommending early intervention all the more.
Segmented and articulated or jointed stent-jackets allow flexion
and the clearing of side branches without resistance, bulging, or
buckling regardless of length, allowing application to any conduit
however extended is the ectasia in length.
[1665] The placement of a stent-jacket along the abdominal aorta,
where the pulse, hence, vasotonic migratory forces are marked, is
positionally stabilized by passing suture through suture loops, or
suture eyelets, integral with the jacket, usually with suture
end-ties prefastened thereto to anchor the jacket to surrounding
tissue at several points above and below where the suture is of
sufficient elasticity (see, for example, Branco, P. S., Cardoso
Junior, M., Rotbande, I., Ciraudo, J. A., Silva, C. R., and Leal,
P. C. 2017. "Elastic Suture (Shoelace Technique) for Fasciotomy
Closure after Treatment of Compartmental Syndrome Associated to
Tibial Fracture," Revista Brasileira de Ortopedia [Brazilian
Journal of Orthopedics] 52(1):103-106; Lambertz, A., Vogels, R. R.,
Busch, D., Schuster, P., Jockenhovel, S., and 3 others 2015.
"Laparotomy Closure Using an Elastic Suture: A Promising Approach,"
Journal of Biomedical Materials Research. Part B, Applied
Biomaterials 103(2):417-423; Simon-Allue, R., Perez-Lopez, P.,
Sotomayor, S., Pena, E., Pascual, G., Bellon, J. M., and Calvo, B.
2014. "Short- and Long-term Biomechanical and Morphological Study
of New Suture Types in Abdominal Wall Closure," Journal of the
Mechanical Behavior of Biomedical Materials 37:1-11; Bellon, J. M.,
Perez-Lopez, P., Simon-Allue, R., Sotomayor, S., Perez-Kohler, B.,
and 3 others 2014. "New Suture Materials for Midline Laparotomy
Closure: An Experimental Study," BioMed Central Surgery 14:70) as
not to significantly pull at and injure the tissue.
[1666] The need for outrigger stabilizers or dummy collars as shown
in FIG. 16, part number 124 in addition to suture loops (or suture
eyelets), or end-ties should prove seldom necessary. By comparison,
endoluminal stents provide no way to prevent migration other than
by protrusion of relatively thin struts, wire, or prongs into the
endothelium or urothelium, for example, which then acts as a
chronic irritant to the substrate ductus.
[1667] Without stabilizing means, migration is a problem whether
the means of aneurysmal containment is extra or endoluminal (see,
for example, Filis, K. A., Galyfos, G., Sigala, F., Tsioufis, K.,
Tsagos, I., and 3 others 2017. "Proximal Aortic Neck Progression:
Before and After Abdominal Aortic Aneurysm Treatment," Frontiers in
Surgery 4:23; Spanos, K., Karathanos, C., Saleptsis, V., and
Giannoukas, A. D. 2016. "Systematic Review and Meta-analysis of
Migration after Endovascular Abdominal Aortic Aneurysm Repair,"
Vascular 24(3):323-336; Pintoux, D., Chaillou, P., Azema, L.,
Bizouarn, P., Costargent, A., Patra, P., and Goueffic, Y. 2011.
"Long-term Influence of Suprarenal or Infrarenal Fixation on
Proximal Neck Dilatation and Stentgraft Migration after EVAR
[endovascular aortic repair]," Annals of Vascular Surgery
25(8):1012-1019; Benharash, P., Lee, J. T., Abilez, O. J.,
Crabtree, T., Bloch, D. A., and Zarins, C. K. 2007. "Iliac Fixation
Inhibits Migration of Both Suprarenal and Infrarenal Aortic
Endografts," Journal of Vascular Surgery 45(2):250-257; Litwinski,
R. A., Donayre, C. E., Chow, S. L., Song, T. K., Kopchok, G.,
Walot, I., and White, R. A. 2006. "The Role of Aortic Neck Dilation
and Elongation in the Etiology of Stent Graft Migration after
Endovascular Abdominal Aortic Aneurysm Repair with a Passive
Fixation Device," Journal of Vascular Surgery 44(6):1176-1181;
Zarins, C. K., Bloch, D. A., Crabtree, T., Matsumoto, A. H., White,
R. A., and Fogarty, T. J. 2003. "Stent Graft Migration after
Endovascular Aneurysm Repair: Importance of Proximal Fixation,"
Journal of Vascular Surgery 38(6):1264-1272).
[1668] Not requiring tissue perforation with suture or incision,
infection is less likely, and sealing the aneurysmal segment round
and about, continued enlargement (see, for example, Nakai, M.,
Ikoma, A., Sato, H., Sato, M., Nishimura, Y., and Okamura, Y. 2015.
"Risk Factors Associated with Late Aneurysmal Sac Expansion after
Endovascular Abdominal Aortic Aneurysm Repair," Diagnostic and
Interventional Radiology 21(3):195-201; Dubenec, S. R., White, G.
H., Pasenau, J., Tzilalis, V., Choy, E., and Erdelez, L.2003.
"Endotension. A Review of Current Views on Pathophysiology and
Treatment," Journal of Cardiovascular Surgery (Turin, Italy)
44(4):553-557) is counteracted.
[1669] Continued enlargement is suppressed whether the cause is
endoleakage or endotension, the latter hypothesized to result from
either an imperceptible endoleak (Lin, P. H., Bush, R. L., Katzman,
J. B., Zemel, G., Puente, O. A., Katzen, B. T., Lumsden, A. B.
2003. "Delayed Aortic Aneurysm Enlargement Due to Endotension after
Endovascular Abdominal Aortic Aneurysm Repair," Journal of Vascular
Surgery 38(4):840-842; Veith, F. J. and Baum, R. A. (eds.) 2002.
Endoleaks and Endotension: Current Consensus on Their Nature and
Significance, New York, N.Y.: Informa HealthCare) or increased
graft permeability (Kougias, P., Lin, P. H., Dardik, A., Lee, W.
A., El Sayed, and H. F., Zhou, W. 2007. "Successful Treatment of
Endotension and Aneurysm Sac Enlargement with Endovascular Stent
Graft Reinforcement," Journal of Vascular Surgery 46(1):
124-127).
[1670] Certain circumstances do recommend endovascular repair (see,
for example, Zettervall, S. L., Ultee, K. H., Soden, P. A., Deery,
S. E., Shean, K. E., and 3 others 2017. "Predictors of Renal
Dysfunction after Endovascular and Open Repair of Abdominal Aortic
Aneurysms," Journal of Vascular Surgery 65(4):991-996; Spanos, K.,
Karathanos, C., Athanasoulas, A., Saleptsis, V., Vasilopoulos, I.,
and 3 others 2017. "Renal Function Impairment in Patients
Undergoing Elective EVAR vs. Elective Open Repair During Follow up
Period: A Systematic Review of the Literature," Current Vascular
Pharmacology 15(2): 103-111).
[1671] Where the kidneys are distant, however, likely the result of
presuming that with a transluminal procedure available, an open
procedure should be avoided at all costs, a failure to fully
envelop the aneurysm within a nonself-expanding, unyielding,
nonstretchable jacket (which can be curved for use in the thorax or
bifurcated for use in the abdomen) or by conventional open surgical
repair, using a conventional endoluminal stent graft, continued
enlargement and even rupture of both abdominal and thoracic aortic
aneurysms is indeed possible (see, for example, Ultee, K. H. J.,
Zettervall, S. L., Soden, P. A., Darling, J., Verhagen, H. J. M.,
and Schermerhorn, M. L. 2017. "Perioperative Outcome of
Endovascular Repair for Complex Abdominal Aortic Aneurysms,"
Journal of Vascular Surgery 65(6):1567-1575; Ultee, K. H., Soden,
P. A., Zettervall, S. L., Darling, J., Verhagen, H. J., and
Schermerhorn, M. L. 2016. "Conversion from Endovascular to Open
Abdominal Aortic Aneurysm Repair," Journal of Vascular Surgery
64(1):76-82; Kasahara, H., Hayashi, I., and Haijima, N. 2015.
"Aneurysm Growth after Late Conversion of Thoracic Endovascular
Aortic Repair," SAGE [Publications] Open Medical Case Reports
3:2050313X14565422; Dalainas, I. and Xiromeritis, K. 2010. "Aortic
Neck Dilatation and Endograft Migration after EVAR [endovascular
aortic repair]," Journal of Endovascular Therapy 17(6):685-686;
Oberhuber, A., Schwarz, A., Hoffmann, M. H., Klass, O., Orend, K.
H., and Muhling, B. 2010. "Influence of Different Self-expanding
Stent-graft Types on Remodeling of the Aortic Neck after
Endovascular Aneurysm Repair," Journal of Endovascular Therapy
17(6):677-684; Moulakakis, K. G., Dalainas, I., Mylonas, S.,
Giannakopoulos, T. G., Avgerinos, E. D., and Liapis, C. D. 2010.
"Conversion to Open Repair after Endografting for Abdominal Aortic
Aneurysm: A Review of Causes, Incidence, Results, and Surgical
Techniques of Reconstruction," Journal of Endovascular Therapy
17(6):694-702; Thomas, B. and Sanchez, L. 2009. "Proximal Migration
and Endoleak: Impact of Endograft Design and Deployment
Techniques," Seminars in Vascular Surgery 22(3):201-206; Orra, H.
A., Puech-Leao, P., Silva, E. S., and Silva, D. G. 2008. "Aneurysm
Pulsatility after Endovascular Exclusion--An Experimental Study
Using Human Aortic Aneurysms," Clinics (Sao Paulo, Brazil)
63(1):67-70; Lin, P. H., Bush, R. L., Katzman, J. B., Zemel, G.,
Puente, O. A., Katzen, B. T., and Lumsden, A. B. 2003. "Delayed
Aortic Aneurysm Enlargement Due to Endotension after Endovascular
Abdominal Aortic Aneurysm Repair," Journal of Vascular Surgery
38(4):840-842).
[1672] While an incipient aneurysm would shrink if bypassed or
excluded with a stent-graft, under the guidelines stated above, it
would not be treated at this early stage. The aneurysmal wall is
reduced to some extent with an endovascular lining (endograft,
internal bypass graft; endoprosthesis) in place, but recovery is
necessarily without exposure to the flow of blood, and the various
means stated are for all practical purposes irrecoverable once
applied. Neither is there reason to assume that the earliest
intervention would allow an aneurysm to actually heal and regain
wall strength rather than just shrink so that a temporary
(absorbable) stent-jacket could be used to contain it only so long
as sufficient strength took to develop. Indeed, the repair of an
aneurysm at one location may lead to another at the next weakest
point along the vessel. Circumductal (periductal) stents, with or
without implants or circumvascular bonding but with a side-slit and
thus compliant with smooth muscle action, can also be used to close
off fistulae.
[1673] In veterinary practice, a less radical than conventional
highly traumatic procedure for the repair of tracheal collapse
would likewise encourage intervention before this invariably
progressive condition could result in asphyxia. Whereas the
preceding applications involve containment, stenotic conditions, to
include tracheal collapse, require that the wall of the ductus be
retracted radially outwards. The radical surgery normally performed
to accomplish this is avoided by laproscopically inserting wide,
usually cyanoacrylate cement-coated, ferromagnetic stays along and
to either side of the collapsed dorsal ligament and a base-tube
surrounding the ductus having tiny magnets with which to draw the
spherules outwards. Since the flaccidity tends to gain in length,
the segment included is deliberately overextended. Implantation
from within the lumen into the wall of the ductus of small
ferromagnetic spherules requires greater skill.
[1674] To reduce the risk of migration, the stent-jacket:
[1675] 1. Resiliently grasps about the vessel or duct with the
least magnetic force.
[1676] 2. Can often be safely extended over a greater length than
an endoluminal stent. 3. Can thus have a greater contact area while
less aggressively maintaining the ductus patent.
[1677] 4. Is lined with a moisture barrier-coated viscoelastic
polyurethane foam cushion, firmer but nonincisive projections,
gauze, or a surface that is textured, which also increases the
surface area for tissue integration by infiltration and adhesion of
a sealant, adhesive, antibiotic, or other medicated coating.
[1678] 5. Can be bonded in whole or part to the outer surface of
the substrate ductus regardless of the lining used, and
[1679] 6. Have wrap-around straps or ties (end-ties, end tethers)
at one or both ends. An individual stent-jacket spans side branches
with a hole at the end of a slit cut from the side-slit or
side-slot with no risk as there is with an endoluminal stents that
the lumen wall might prolapse through the mesh.
[1680] Alternatively, articulated and special purpose stent-jackets
can span side-branches, attachments, bends, and points of flexion
with no less compliance to peristalsis or the pulse. The spherules
and/or the internal surface of the stent-jacket can be medicated or
irradiating. The stent-jacket lining is bonded inside the base-tube
by ultrasonic welding or an adhesive. Adhesives for bonding gauze
within the stent-jacket, for example, are specified below in the
section entitled Stent- and Shield-jacket Anti-migration Linings.
The apparatus to be described includes means for adding a tough
outer layer about a weak or malacotic vas or ductus without the
strength required to support a tractive magnetic force, means for
recovering loose and for extracting mispositioned spherules or
stays, for testing airgun control settings for the force of impact
necessary to seat the spherule implants in the diseased tissue
encountered in situ quickly, and for motorization of the
muzzle-head.
[1681] The ability to induce an implant to generate heat
noninvasively has numerous applications. Applying such function to
a ductus not open to the exterior and precluded from the use of
magnetic resonance for imaging where collateral heating of the
implant could prove harmful (see, for example, Prasad, S. K. and
Pennell, D. J. 2004. "Safety of Cardiovascular Magnetic Resonance
in Patients with Cardiovascular Implants and Devices," Heart
90(11):1241-1244), demands an assessment as to the prospective need
for such imaging and the difficulty of recovering the implant in
that event; recovery like placement necessitates exposure through a
small incision and the need to dissect the ductus to allow its
partial or complete encirclement by the stent-jacket, or
extraductal component of an extraluminal stent.
[1682] Older technology pacemaker and cardioverter defibrillator
implants may require any device incorporating a permanent magnet to
be kept at a minimum distance. When undesirable, heating can be
reduced if not eliminated (see, for example, McElcheran, C. E.,
Yang, B., Anderson, K. J., Golenstani-Rad, L., and Graham, S. J.
2015. "Investigation of Parallel Radiofrequency Transmission for
the Reduction of Heating in Long Conductive Leads in 3 Tesla
Magnetic Resonance Imaging," Public Library of Science One
10(8):e0134379).
[1683] I2. Structural and Functional Considerations
[1684] A description of stent-jackets in terms of parts is provided
in the sections above entitled The Extraductal Component of the
Extraluminal Stent and the Means for its Insertion and Description
of the Preferred Embodiments. The materials of and various
modifications to stent-jackets are no less significant. In an
extrinsic stent-jacket, the magnets are preferably unitized with
the base-tube before the lining is bonded to its internal surface
by dip or spin coating polymer encapsulation. To allow portions of
the base-tube to be snipped away to clear attachments, for example,
the base-tube must be approved for implantation without the
protective coating.
[1685] Stent-jackets consist of a base-tube, part number 5 in FIGS.
2 thru 7, made of rolled, intrinsically magnetized, metal sheet, or
comprise polymer sheet with small permanent or electromagnets
fastened about the outer surface. When the intraluminal susceptible
matter, usually consisting of microspherules comprising compacted
superparamagnetic iron oxide nanoparticles, a stent-jacket with
permanent magnets is used to cause the microspherules to abut in
pressing relation against the endothelium or urothelium, for
example.
[1686] When the intraluminal susceptible matter is to be drawn into
the intima, the stent-jacket has small electromagnets fastened
about the outer surface of the base-tube. Further structural
details pertaining to stent-jackets and the means for imparting
high tractive force to small electromagnets appear herein in
several locations. A radial projection catheter can be used to
inject susceptible matter with or without medication adherent to or
impregnated therein into the intima with any type stent-jacket or
impasse-jacket.
[1687] Pending unitization thus, the magnets are tacked in position
with cyanoacrylate cement, or if larger in diameter, a viscous
cement that will take up the nontangent interface between the
magnet edges and the base-tube. Since removal to fit may approach
the magnets, these must have been chemically isolated such as by
vapor deposition or plating with titanium or gold, for example,
before encapsulation, and the tacking cement must have been
approved for implantation. Loctite Hysol Cool Melt.RTM., which
melts at 250 degrees Fahrenheit, well below the Curie temperature
of neodymium iron boron magnets, to cite but one commercial
adhesive, and cyanoacrylate cements generate relatively negligible
exothermic heat during polymerization (setting), which varies as
the setting time, can be used.
[1688] The surface of the base-tube to which the magnets are to be
bonded are etched or scored with surface undercuts for more secure
adhesion. The magnets should not require to be specially molded to
create an arcuate internal surface or the base-tube specially
extruded or machined with longitudinal planar arcs for attachment
of the magnets; when the thickness of the stent-jacket must be
minimized, the use of an intrinsically magnetized stent-jacket is
indicated. The base-tube 5 with magnets 4 and any rivets is
chemically isolated by polymeric dip-coating encapsulation before
the lining is bonded to its internal surface.
[1689] Once completed, individual stent-jackets may be strung
together into a linked succession of stent- and/or impasse-jackets
of like or different kinds as dictated by the medical requirements.
To assure the versatility demanded, such a linked succession, as
addressed below in the sections entitled Sectional, or
Chain-stents, Segmented and Articulated and Braced, Compound, and
Chain Impasse-jackets, is not presequenced and chemically isolated
as an intact train of manufacture but is freely assembled. For
inserting rivets to secure jacket to jacket connecting wires,
jackets to be connected are punched with a single pair of bilateral
holes toward the ends of the base-tube, breaking the chemically
isolating seal of the encapsulating coating.
[1690] To provide chemical isolation for the chain, flat flanged
short straight barrel rivets of titanium anodized aluminum, another
nonferrous metal, or nonmagnetic stainless steel are used to attach
the thin bilateral nonmagnetic stainless steel wires used to
connect one jacket to the next. Further protection against a break
in the isolating seal is attained through the use of base-tube
materials approved for medical use by the Food and Drug
Administration, such as Polymer Technology Group, Incorporated
Bionate.RTM. polycarbonate based polyurethane copolymer of
durometer D-scale 55 and silicone-urethane copolymers. Since
pressing the rivets closed is likely to produce microfractures in a
plated surface exposing a non-biocompatible substrate, material,
conventional electroplating is avoided, although certain types of
vapor deposition such as addressed below in this section may prove
satisfactory.
[1691] The rivets should be pressed in with enough force to draw
the heads on the internal surface of the base-tube up into the
lining and flush to the inner surface as not to protrude through
the lining and into the encircled adventitia or fibrosa. Consistent
with the need for compliance with expansion and contraction of the
substrate ductus and to minimize tangent separation at the magnet
ends, the magnets are applied to the outer surface of the base-tube
longitudinally along the length of the base-tube. The magnets or
intrinsic magnetization of the jacket is normal to the long axis.
Within the constraint that the flexibility of the base-tube should
not significantly impeded, using more expansive magnets reduces the
criticality of magnet positioning relative to the miniball or stay
implants.
[1692] Since stays have circumferential extension, these are easier
to overlay with magnets mounted to a base-tube than are miniballs.
When magnet overlay alignment is problematic, an additional measure
is to use an intrinsically magnetized stent-jacket. Distinctions in
magnetic strength along a single stent-jacket to accommodate
variability in the retentive strength (resistance to pull-through)
of the tissue treated is seldom appropriate; wide differences in
the magnetic strength suitable for proximate locations bode not
just implant local pull-through but more extensive rupture, so that
only the least functional strength is uniformly applied.
Disease-weakened eccentric (radially asymmetrical) tissue is
omitted from implantion and subjection to tractive force, the
stent-jacket with a magnet-blanked area positioned with the aid of
continuous fluoroscopic monitoring.
[1693] Offset stretches of a stenosed ductus that vary in wall
strength among affected segments are treated with a segmented or
chain-stent wherein the sub-stents are selected for the safe
strength to be used as are questions of least functional strength
generally, based upon the results of the in situ test described
below in the section entitled Testing and Tests. If distinctions in
magnetic strength along a single stent-jacket are felt justified,
placing miniballs or stays of different magnetic strength and then
positioning a stent-jacket with uniformly strong magnets is easier
and more economical than is the opposite of apposing magnets of
different strength to designated ductus-intramural implants. Either
approach demands the use of continuous fluoroscopic monitoring to
reveal the position of the ductus-intramural implants as the jacket
is placed and allow the apposition required.
[1694] Expansion inserts are addressed below in the section
entitled Expansion Inserts Absorbable, Meltable, and Comminutable
for Time-discrete Decremental Contraction of Stent-Jackets and
shown in FIGS. 7 thru 9. A side-slot provides a greater width than
a side-slit to allow the stent-jacket to clear a connective tissue
attachment or adhesion wanted preserved, so that the slot is
unavailable for an expansion insert. When clearance must be
provided to pass a nervelet, for example, a portion of the
base-tube bordering the edge of the slit is nibbled or snipped
away. Expansion inserts are intended to be temporary and most are
intended to be disintegrated by exposure to the internal
environment, so that these are applied only after the base-tube
with magnets has been encapsulated as are linings
[1695] Stent-jackets and articulated stent-jackets placed in
locations that pose conditions with inordinate potential to
displace these have side-straps and/or end-ties as described below
as an additional precaution against migration (lateral displacement
along the substrate ductus). Stent-jackets serve the primary
purpose of maintaining the patency of the substrate ductus and can
serve a secondary purpose in attracting and thus targeting magnetic
drug carriers into the encircled wall. Where stenting is
uninvolved, impassable holding jackets, as addressed above in the
section entitled Endoluminal Prehension of Miniballs and
Ferrofluids, among others, and/or strongly magnetized miniballs or
stays, as addressed above in the section entitled Drug-targeting
Miniballs and Stays, among others, are preferable for attracting,
trapping, or suspending drug delivering miniballs and attracting
magnetic drug carrier particles.
[1696] As addressed above in the section entitled Concept of the
Extraluminal Stent and the Means for its Placement, the use of an
extraluminal magnetic stent to include both the extravascular and
intravascular components, is generally limited to conditions that
make its use advantageous if not imperative, usually to maintain
patency of the affected ductus with minimal impact on normal
function. Once placed in a minor surgical procedure involving a
local incision without a transluminal component, the extravascular
component of an extraluminal stent, consisting of the polymeric
base-tube with magnets or a magnetized jacket alone can thereafter
be used as would an impasse-jacket for magnetic drug or
radionuclide targeting.
[1697] Should the ductus become stenosed, the intravascular
component of the magnetic stent consisting of stenting miniballs
can be placed transluminally at any later date. Stays, by contrast,
whether medicinal, magnetized, radiation-emitting, and/or to serve
as the intravascular component of a magnetic stent, are placed
through the same access portal as the stent-jacket and then blocked
from access unless the interposed stent-jacket is removed. As the
circumductal (perivascular) component of an extraluminal magnetic
stent, stent-jackets can be used to maintain the patency of any
tubular anatomical structure that can be encircled (collared,
mantled) without the need for more dissection than a side-slot or
cut-outs would allow.
[1698] Virtually all stent-jackets, whether polymeric with applied
bar magnets or made of magnetized metal, include apertures to
provide contact between the adventitia or fibrosa and the
surrounding chemical milieu as well as to discourage atherogenesis
(see, for example, De Meyer, G. R. Y., Van Put, D. J., Kockx, M.
M., Van Schil, P., Bosmans, R., Bult, H., Buyssens, N., Vanmaele,
R., and Herman, A. G. 1997. "Possible Mechanisms of Collar-induced
Intimal Thickening," Arteriosclerosis, Thrombosis, and Vascular
Biology 17(10):1924-1930). Apertures are omitted from FIG. 5 to
allow the intraductal miniballs to be seen through the
stent-jacket.
[1699] Any stent- or impasse-jacket can be prepositioned about the
site of an incipient, advanced, or anticipated lesion or neoplasm,
or one pending or following excision or resection to apply or
support treatment not involving the placement of intraductal
miniballs for an indeterminate period, if ever. Unlike an
absorbable stent, once placed alone, a stent-jacket can be used at
any future time. Unlike an endoluminal stent, an extraluminal stent
leaves the lumen clear so that magnetic drug carrier particle or
nanoparticle medication or radiation, for example, is not drawn to
the stent but rather up against and into the lesion. Leaving the
lumen clear, transluminal procedures are not hampered by the
earlier placement of even several extraluminal stents.
[1700] For use with radiation-emitting miniballs and ferrofluids,
the tissue of the ductus wall must be confirmed to be strong enough
to prevent pull-through. A barrel-assembly can pass without
obstruction other than might be posed by the lesion itself, which
the barrel-assembly is equipped to negotiate by ejecting a
lubricant, oscillating the muzzle-head, and/or through thermal or
mechanical ablation. Any stent-jacket can have an outer radiation
shield heat or adhesive bonded or plastic welded to it as a
flexible outer layer containing overlapping shielding particulates
of tungsten, platinum, gold, or an alloy thereof in a polymeric
matrix, as addressed above in the section entitled System Implant
Magnetic Drug and Radiation Targeting. Due to toxicity and
scarcity, osmium and osmium-iridium alloys are not used.
[1701] Materials preferred for radiation shielding exclude lead,
depleted uranium, and depleted plutonium as toxic, the first also
decidedly suboptimal in shielding efficiency for the tiny
dimensions involved. The shielding particulate is tightly but
flexibly embedded in overlapping relation within a chemically
isolating matrix layer of a rubbery polymer. Such a shield serves
both to reduce the dose received by the ductus from externally
applied radiation and to protect the tissue surrounding the ductus
from radiation emitted by radioactive miniballs or stays, for
example. Depending upon the type of radiation, a shield of
overlapping particulate tungsten should almost never interfere with
the ability to heat the magnets mounted about the base-tube of a
polymeric or a ferrous metal base-tube for the purpose of warming
the adventitia.
[1702] A radiofrequency alternating magnetic field can be used to
warm the jacket and therewith, the adventitia with imaging used to
view the muzzle-head, which can be aligned to the stent-jacket
within the lumen to heat the lumen wall from within at the same
time or for applying any emissive, ejective, ablative, or
angioplastic process of which it is possible. Stent- and
impasse-jackets can be heated to warm the encircled ductus for
magnetic hyperthermia, or to heat miniballs or microspheres
suspended by a jacket in the lumen to initiate or accelerate the
release of a drug or its rate of uptake, or to heat drug carrier
nanoparticles once drawn into the lumen wall whether as
hyperthermia, to initiate or increase the rate of drug uptake, or
to dissipate or accelerate the dissipation of absorbable
components, or any of these purposes in combination.
[1703] Heat may be used to flow a bonding agent such as a protein
solder or release a drug from a miniball or stay, for example.
Outside the lumen, an absorbable jacket or component thereof is
less exposed to the enzymatic and hydrolytic action that causes its
breakdown. The application of heat can be used to dissipate or
accelerate the rate of chemical action involved in its dissipation
and thus compensate for the reduced exposure of extraluminal
placement. Absorbable elements can be seeded, doped, or chemically
incorporate a substance that when warmed is released and dissolves
the breakdown of the structure incorporating it. Whereas a
stent-jacket with a polymeric base-tube inherently provides thermal
insulation for circumvasclar tissue when the muzzle-head is used to
apply heat, an intrinsically magnetized stent-jacket must have a
polymeric layer added to its outer surface; conversely, the latter
can serve as a bidirectional heat-sink when desired.
[1704] With or without a radiation shield, the outer surface of a
stent-jacket with a polymeric base-tube can be increased in thermal
insulation by adding a suitable polymeric coating. If drawing
magnetically susceptible drug- or radiation-emitting carrier
particles or nanoparticles by the jacket without magnetic
retraction and thus without a transluminal component fails to
preclude stenosis, then a barrel-assembly is used to introduce
miniballs to stent the ductus with or without continuing the same
or different medication and/or radiation. If miniballs are placed
immediately, then the stent-jacket will also serve to draw
supportive medication infused upstream. The advent of orally
administered magnetic drug-targeting as addressed above in the
section entitled System Implant Magnetic Drug and Radiation
Targeting, will increase the applications for impasse- and
stent-jackets.
[1705] Such prepositioning is accomplished when a ductus
lumen-intramural lesion such as cancerous or atheromatous, for
example, is discovered and to stage treatment by deferring a
transluminal procedure until necessary, would spare the patient
discomfort. To include larger ductus, such as the abdominal aorta,
trachea, and gastrointestinal tract, a shielding stent-jacket can
be used to protect the ductus from radiation applied externally to
treat circumvascular tissue, or reciprocally, to protect the
surrounding tissue from radiation, such as applied to the wall of
the ductus. Involving no a transluminal component, the
prepositioned jacket can be used to trap an oncolytic radionuclide-
(radioisotope-) when infused upstream in microspheres or a
ferrofluid. Once placed the jacket need not be recovered but can
remain in place indefinitely where it will support retreatment at a
later date.
[1706] Magnetic drug and radionuclide-bound drug carrier
nanoparticle or microsphere targeting can be used to supplement or
eliminate the requirement for intrinsic affinity-based chemical,
physiological, or metabolic uptake of the drug or therapeutic
substance by the target organ or tissue. The placement of small
neodymium patch-magnets beside the lobes of the thyroid gland, for
example, allows limitation to iodine-125 or iridium-192 isotope,
for example, to be expanded to any magnetically susceptible or
susceptibly carried substance (see, for example, Kaufman, H. L,
Wadler, S., and Antman, K. (eds.) 2008. Molecular Targeting in
Oncology, Totowa, N.J.: Humana Press) and a nonphysiologic agent
used instead. By the same token, the bonding of a radionuclide to a
substance normally assimilated by a certain organ, such as is
Iodine-125 or 131 by the thyroid gland, historically intentional,
can be averted were it introduced before it reaches the thyroid and
drawn into other tissue.
[1707] Uptake by the thyroid gland could be much reduced if not
eliminated and redirected to a kidney by injecting the
ferrofluid-borne iodine isotope-bound drug carrier nanoparticulate
directly into the renal artery, for example, with uptake by the
kidney mechanically enhanced by a clasp-magnet or magnets,
addressed above in the section entitled Clasp-magnets, fixed to the
renal fibrosa. The delivery of drugs to the thyroid gland with or
without iodine is by fastening tiny patch-magnets to the fascia
overlying the infrahyoid and if necessary, sternocleidomastoideus
muscles. These implants can be almost entirely absorbable, only
small spherules of neodymium iron boron within a chemically
isolating shell remaining. Incorporating ferrous metal in these
spherules makes it further possible to use a powerful external
electromagnet to extract these entirely out of the body, the tiny
perforations readily disinfected and healing.
[1708] Extraction thus is effected with a very powerful pulse that
accelerates the spherules to a velocity that shock perforates the
integument at the triangle rather than pulls the tissue abaxially
until its bursting strength is exceeded. If the condition treated
warrants deeper dissection, impasse-jackets are placed at the
inlets to the gland on the paired superior and inferior thyroid
arteries and infrequently, the unpaired or paired thyroidea ima
(artery of Neubauer, thyroid artery of Neubauer, lowest thyroid
artery). These vessels anastomose over the surface of the gland;
however, by singling out a particular artery for impasse-jacketing
and/or the placement of a patch-magnet if applicable, the drug can
be skewed toward the area predominantly supplied by that
vessel.
[1709] Placement follows the condition treated, a unilateral
condition generally suited to the unilateral placement of a holding
jacket. Impasse-jackets to release a reversal agent to counter any
residueare placed on the superior and inferior thyroid veins only
to prevent adverse side effects when necessary. Where the drug or
drugs must be administered three times a day, local release from a
holding jacket is not feasible, the oral route requiring
introduction as a ferrofluid devised to pass through the gut, the
liver, and into the systemic circulation. Drugs not requiring
frequent dosing can be directly injected into the external carotid
and if necessary, the thyrocervical trunk, again based upon the
regional concentration desired within the thyroid.
[1710] The severity of the condition must justify laparoscopic
placement of a clasp-magnet or impasse-jacket; however, once
accomplished, either can be left in place indefinitely for later
use to cause the uptake by the kidney of the same of any other
magnetic drug carrier bound substance. When the need for future
reimaging is prognostic, Iodine 123 used for myocardial perfusion
imaging can be concentrated with magnetic targeting that uses an
impasse-jacket or clasp-magnet. Shielded stent-jackets, addressed
above in the section entitled System Implant Magnetic Drug and
Radiation Targeting, also allow the use of miniballs and stays of
higher dose-rate, but lacking the grid of an impasse-jacket
provided to allow noninvasive extraction with the aid of an
external electromagnet, constitute an obstruction if these are to
be extracted prior to decaying.
[1711] Unlike impasse-jackets, stent-jackets are not configured for
extraction of the trapped or held miniball or miniballs through an
open mesh wire grid with the aid of an external electromagnet, nor
can these incorporate a radiation shield. Since a shielded jacket
must be accessed for retrieval through a local incision and the
radiation miniballs, whether ductus-intramural or suspended within
the lumen can only be safely recovered with the recovery
electromagnets in a barrel-assembly muzzle-head, local reentry for
retrieval is is avoided and vacated shielded stent-jacket left in
place. Vascular radiation is typically obtained from phosphorus,
yttrium, strontium, and rhenium radioisotopes, for example.
[1712] The shielding and extraction described herein accordingly
allow dispensing with repeated invasive treatment in order to
employ more intensive radiation (see, for example, Wade, J.,
Krause, B. J., Nusser, T., Kochs, M., and Hoher, M. 2006. "Repeat
Intracoronary Beta-brachytherapy Using a Rhenium-188-filled Balloon
Catheter for Recurrent Restenosis in Patients who Failed
Intracoronary Radiation Therapy," Cardiovascular Revascularization
Medicine 7(1):2-6; Chu, W. W., Torguson, R., Pichard, A. D.,
Satler, L. F., Chan, R., and 4 others 2005. "Drug-eluting Stents
Versus Repeat Vascular Brachytherapy for Patients with Rrecurrent
In-stent Restenosis after Failed Intracoronary Rradiation," Journal
of Invasive Cardiology 17(12):659-662; Kuchulakanti, P., Torguson,
R., Canos, D., Satler, L. F., Suddath, W., and 8 others 2005.
"Optimizing Dosimetry with High-dose Intracoronary Gamma Radiation
(21 Gy) for Patients with Diffuse In-stent Restenosis,"
Cardiovascular Revascularization Medicine 6(3):108-112; Eeckhout,
E., Roguelov, C., Berger, A., Lyon, X., Imsand, C., Girod, G., and
Coucke, P. 2005. "Repeated Beta Irradiation for Failed
Intracoronary Radiation Therapy in Patients with In-stent
Restenosis," Heart 91(6):823-824; Waksman, R., Lew, R., Ajani, A.
E., Pichard, A. D., Satler, L. F., and 9 others 2003. "Repeat
Intracoronary Radiation for Recurrent In-stent Restenosis in
Patients Who Failed Intracoronary Radiation," Circulation 108(6):
654-656).
[1713] An endoluminal stent difficult and risky to retrieve, a
shielded jacket allows the use of more intense radiation than an
endoluminal stent can be allowed to emit (see, for example,
Cervinka, P., Stasek, J., Costa, M. A., Stursa, J., Fiser, M., and
5 others 2004. "Intravascular Ultrasound Study of the Effect of
Beta-emitting ((55)Co) Stents on Vascular Remodeling and Intimal
Proliferation," Catheterization and Cardiovascular Interventions
61(3):320-325; Cervinka, P., St'asek, J., Costa, M. A., Stursa, J.,
Fiser, M., and 5 others 2004. The "Edge Effect" after Implantation
of Beta-emitting (55Co) Stents with High Initial Activity," Acta
Medica (Czech Republic) 47(1):37-42; Wardeh, A. J., Albiero, R.,
Kay, I. P., Knook, A. H., Wijns, W., and 7 others 2002.
"Angiographical Follow-up after Radioactive "Cold Ends" Stent
Implantation: A Multicenter Trial," Circulation 105(5):550-553;
Kay, I. P., Wardeh, A. J., Kozuma, K., Foley, D. P., Knook, A. H.,
and 5 others 2001. "Radioactive Stents Delay But Do Not Prevent
In-stent Neointimal Hyperplasia," Circulation 103(1):14-17;
Albiero, R. and Colombo, A. 2000. "European High-activity (32)P
radioactive Stent Experience," Journal of Interventional Cardiology
12(8):416-421; Coen, V. L., Knook, A. H., Wardeh, A. J., van der
Giessen, W. J., De Pan, C., and 6 others 2000. "Endovascular
Brachytherapy in Coronary Arteries: The Rotterdam Experience,"
Cardiovascular Radiation Medicine 2000 2(1):42-50; Hehrlein, C. and
Kubler, W. 1997. "Advantages and Limitations of Radioactive
Stents," Seminars in Interventional Cardiology 2(2):109-113;
Hehrlein, C., Gollan, C., Donges, K., Metz, J., Riessen, R.,
Fehsenfeld, P., von Hodenberg, E., and Kubler, W. 1995. "Low-dose
Radioactive Endovascular Stents Prevent Smooth Muscle Cell
Proliferation and Neointimal Hyperplasia in Rabbits," Circulation
92(6):1570-1575).
[1714] Once placed, a stent-jacket as well as a magnet-jacket and
an impasse-jacket, designed for the purpose, can serve as a holding
jacket, as addressed above in the section entitled Concept of the
Impasse-jacket, and below in the section entitled Miniball and
Ferrojluid-borne Particle-impassable Jackets, or Impasse-jackets,
that allows:
[1715] 1. The magnetic targeting of drug carrier nanoparticles, as
addressed above in the section entitled System Implant Magnetic
Drug and Radiation Targeting, differential targeting achieved by
graduating the amount of magnetically susceptible content of the
drug carrier particles and/or the strength of magnetization of the
stent-, magnet-, and/or impasse-jackets along the ductus, and
[1716] 2. Stopping and retaining any miniball that enters the
circulation upstream. Shcould this occur midprocedurally, the
barrel-assembly will be positioned to move through the
prepositioned stent-jacket using its recovery electromagnets to
retrieve the seized miniball; otherwise, a stent-jacket is not
confirgured for extraction.
[1717] If the radioisotope has a longer half-life than would decay
within a safe interval, it is is removed postprocedurally with the
recovery electromagnets in a barrel-assembly. Once placed, a
stent-jacket, impasse-jacket, or magnet-jacket constitutes a
prepositioned magnetic drug-carrier particle targeting device (see,
for example, Kumar, A., Jena, P. K., Behera, S., Lockey, R. F.,
Mohapatra, S., and Mohapatra S. 2010. "Multifunctional Magnetic
Nanoparticles for Targeted Delivery," Nanomedicine 6(1):64-69). In
this capacity, it may be used alone or with other such jackets for
staged targeting, as addressed above in the section entitled System
Implant Magnetic Drug and Radioisotope Targeting. The magnetic
strength required to extract bloodborne drug carrier nanoparticles
is greatest.
[1718] The magnetic strength required to extract blood-borne drug
carrier nanoparticles is greatest. If the strength required exceeds
that of pull-through obtained by testing as addressed below in the
section entitled Testing and Tests, then an impasse-jacket is used.
A stent-jacket placed as a radiation shield is thus seldom used
with ductus-intramural implants to stent. An impasse-jacket is not
designed for stenting and is used without ductus-intramural
implants. Impasse-jackets, or impasse and extraction jackets, are
not configured to present a local magnetic field of uniform
magnitude from one end of the jacket to the other. While the two
types of jacket share some capabilities such as supporting magnetic
drug-targeting requiring less tractive force, attempting to
consolidate the two into a single device only degrades the special
capabilities of both.
[1719] When despite smooth encapsulation, because of its thickness
and/or prominences, a stent-jacket mounting magnets about a length
of polymeric tubing such as shown in FIGS. 2 thru 7 would encroach
upon and irritate tissue surrounding the ductus, an alternative
base-tube made of spring strip metal intrinsically magnetized
normal (radially, perpendicularly) to the longitudinal axis of the
ductus is used. Such a base-tube, coated or encapsulated for
chemical isolation if necessary, allows the small magnets used with
a polymeric base-tube to be eliminated, giving a thinner profile or
cross-section. When compliance with the action in the ductus
requires the intrinsically magnetized stent-jacket to be made of
stock too thin to provide the strength of magnetization required,
the base-tube or another of more compliant plastic is encapsulated
within a polyme layer containing magnetized neodymium iron boron
lanthanoid.
[1720] Reciprocally, when the strength of magnetization required in
all metal stent-jacket necessitates the use of tube stock that is
too thick to comply with the action in the ductus and the coating
method alluded to above is not employed, the jacket must
incorporate spring hinges as in ordinary impasse-jackets. Where a
somewhat greater thickness can be fitted, a metallic stent-jacket
with intrinsic magnetization can enclose a radiofrequency resonant
circuit between inner and outer surfaces that can be heated by
means of an extracorporeal source of radiofrequencies, the heat
used to treat the ductus or miniballs implanted within it. Another
method for achieving the compliance required is that addressed just
below as applied to impasse-jackets whereby spring-hinges join two
semicylindrical base-tube halves which need not be flexible and can
therefore be made as thick as the magnetization requires.
[1721] That hybrid type stent-jackets with spring hinges and a
surrounding or outer layer of polymer embedded lanthanoid or
another that consists of a length of lanthanoid-embedded polymer
tubing are also possible is considered obvious. With openings to
reduce enclosure of the adventita, such stent-jackets resemble
impasse-jackets, as addressed below in the section entitled
Miniball and Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets; however, impasse-jackets must provide the
resistance to deformation under the pull of a powerful external
electromagnet required for miniball extraction, and are limited to
magnetization that to prevent the loss of a suspended miniball
increases toward the longitudinal center and does not extend out to
the ends, or margins. For application where the open mesh wire grid
can be adequately magnetized over a sufficient length for stenting
and strong enough to allow extraction, such an impasse-jacket can
serve as a stent-jacket without radiation shield.
[1722] Broadly, attempting to combine the features of
stent-jackets, made to retract implants within the lumen wall, and
impasse-jackets, made to suspend miniballs and magnetically
susceptible particles within the lumen and allowing these to be
noninvasively extracted, into a single device has the effect of
degrading the performance of the device for both functions.
Distinct and hybrid types all require a moisture barrier-coated
viscoelastic polyurethane foam lining. Made of stock sufficiently
thin, an intrinsically magnetized metal base-tube is preferable for
use where there may be little clearance around the ductus for even
small magnets with rounded corners, as arises, for example, in
peripheral arteries, which course through a compartmentalized
sheath amid other fascial compartments. Access is by dissection
that to the extent possible moves to the pertinent septum with
minimal cutting of muscle.
[1723] Such strip-spring ferrous metal base-tubes with intrinsic
magnetization oriented transversely to the long axis of the tube
are not to be conflated with the alternative spring strip
nonmagnetic metal alloy and polymer combinations for use with
magnets mentioned below. All stent- and shield-jackets as well as
some magnet- and clasp-jackets are provided with a moisture
barrier-coated viscoelastic polyurethane foam lining, and all but
shielded apertures, and side-straps, and/or end-ties to prevent
migration as necessary, and are inserted with a stent-jacket
insertion tool. Thin spring metal stock can be used to make a
base-tube or used as an internal reinforcement to an outer layer or
layers of the polymeric materials to be specified.
[1724] Nonmagnetic magnet-mounting metallic base-tube materials
made of cobalt-nickel-based or copper-beryllium alloy strip
sheeting, for example, with good fatigue resistance can be used as
base-tube materials, as can a specialty nonmagnetic stainless strip
spring steel such as Sandvik Aktiebolag 13RM19. Encapsulation for
chemical isolation is based upon potential toxicity. That to
achieve the desired restorative force, for example, the base-tube
might combine layers of different metallic and polymeric materials
is obvious. A ferrous metal strip spring base-tube magnetized
normal to the longitudinal axis of the ductus and encapsulated for
chemical isolation allows elimination of the small magnets used
with a polymeric base-tube.
[1725] A polymeric layer applied to the outer surface of a
stent-jacket whether shielded but not an impasse-jacket provides
thermal insulation for the surrounding tissue when the jacket is
intentionally heated (well below the Curie temperature) by
placement in a radiofrequency alternating magnetic field.
Increasing the thickness of the encapsulation coating can serve
this purpose as well. Heating can be to warm the ductus
noninvasively for hyperthermia, accelerate the dissolution and
uptake of medication held by the jacket within the lumen, flow a
protein solder outer coating or accelerate the initial setting time
of a cement applied to the miniballs or stays, or accomplish
followup thermoplasty to eliminate intimal or medial hyperplasia,
for example.
[1726] Whether the base-tube is metallic, polymeric, or layers of
each, the need for apertures and a lining of moisture
barrier-coated viscoelastic polyurethane foam as explained in the
sections above entitled Summary Description of the Invention and
Accommodation of the Adventitial Vasculature, Innervation, and
Perivascular Fat applies. Individual subsidiary stents, or
sub-stents, chain-stent as addressed in the section below entitled
Sectional, or Chain-stents, Segmented and Articulated, can have
base-tubes of different materials. A chain-stent is assembled of
sub-stents each selected on the basis of the segment it is to
encircle. A chain combines the antimigrative value of each
component. That is, each sub-stent and/or impasse-jacket
contributes to the rententive forces stabilizing the formation as a
whole. At the same time, it allows each sub-stent or impasse-jacket
to be matched to the medical condition at its respective
location.
[1727] Numerous materials are available for use as the base-tube,
and sensitivity reactions to different materials through patch
testing should be performed before implanting the jacket or
jackets. Since the foam lining prevents contact with the substate
ductus, contact is substantially limited to the outer surface of
the jacket when the magnetized content is not embedded or
sandwiched in the base-tube. Direct contacy easily avoided,
complications that arise with base-tubes made of polymeric
materials such as silicone elastomer involve contact of the
material directly upon cut tissue surfaces, especially in a patient
who is allergic to the material (see, for example, Lee, Y., Song,
S. E., Yoon, E. S., Bae, J. W., and Jung, S. P. 2017. "Extensive
Silicone Lymphadenopathy after Breast Implant Insertion Mimicking
Malignant Lymphadenopathy," Annals of Surgical Treatment and
Research 93(6):331-335; Zambacos, G. J., Molnar, C., and Mandrekas,
A. D. 2013. "Silicone Lymphadenopathy after Breast Augmentation:
Case Reports, review of the Literature, and Current Thoughts,"
Aesthetic Plastic Surgery 37(2):278-289; Winkler, P. A, Herzog, C.,
Weiler, C., and Krishnan, K. G. 2000. "Foreign-body Reaction to
Silastic Burr-hole Covers with Seroma Formation: Case Report and
Review of the Literature," Pathology Research and Practice
196(1):61-66), and the lack of openings along the sides (De Meyer,
G. R. Y., Van Put, D. J., Kockx, M. M., Van Schil, P., Bosmans, R.,
Bult, H., Buyssens, N., Vanmaele, R., and Herman, A. G. 1997.
"Possible Mechanisms of Collar-induced Intimal Thickening,"
Arteriosclerosis, Thrombosis, and Vascular Biology
17(10):1924-1930), none of which applies to the base-tubes
described herein, which if ever made of a silicone elastomer, would
be isolated from the surrounding tissue.
[1728] The issue of adverse tissue reaction when the implant is
sterile is addressed above in the section entitled Significance of
SterileAntixenic Immune Tissue Reaction. A separate stent-jacket
consisting of a single length of side-slit tubing is referred to as
simple, one of a succession of separate stents connected together
in a chain as articulated or jointed with each component
stent-jacket a substent, and a succession of stent-jackets cut into
a continuous length of tubing, segmented. Whereas an articulated
chain-stent is assembled or compiled of individual stent-jackets as
manufactured for the individual application, a segmented stent is
manufactured as continuous thus and trimmed for the individual
application. Trimming consists of snipping away nonessential
intervening substents, snipping away a strip of material adjacent
to the side-strip to create a side-slot, or cutting a single or
successive number of substents off the continuous length as
manufactured, for example.
[1729] Thus, both simple and jointed stent-jackets can include full
round substents to fully encircle the ductus, and partially round
or eliminations of substents to avoid attachments or adhesions to
substrate or adjacent tissue, for example. To prevent injury to the
vasculature supplying the ductus, stent- and impasse-jackets are
lined with visco-elastic, usually, polyurethane moisture
barrier-coated viscoelastic polyurethane foam. This lining leaves
clear perforations or grid openings, so that in a stent-jacket,
only `air holes` are not lined, whereas in an impasse-jacket, the
lining is placed only at the margins and a few circumferential grid
lines as necessary to prevent contact with the adventitia.
[1730] The base-tube is elastic, slit along the side, and sized to
accommodate the pulse or peristalsis. The diameter of the jacket is
based upon the quiescent diameter of the ductus and must expand to
the maximum distended diameter without posing resistance. The
magnetic traction exerted upon the ductus intramural implants
(miniballs or stays) is no more than that essential to preserve
retraction of the ductus against the internal surface of the
stent-jacket. Exceptionally, when the jacket is additionally to
draw drug-carrier particles or miniballs from the lumen contents,
usually blood, the magnetic strength is increased as necessary but
not so much that pull-through or tunical delamination would
result.
[1731] The untreated resistance of the tissue to failure thus is
obtained by means of in-situ testing as addressed below in the
section entitled Testing and Tests, and the prospective resistance
following different treatments through previous experimentation.
When the malacotic condition is more extensive, avoiding
pull-through may necessitate the use of a clasp-jacket lined with a
surface texture and a bonding agent that includes tissue
engineering scaffolding material to support tissue infiltration and
encourage the development of a permanent bond. The clasp-jacket is
entended lengthwise to encircle tissue of normal strength.
[1732] The spandex base should include perforations as not to
completely close off the surface of the ductus. Since both a ductal
component consisting of a clasp-jacket or stays and the extraductal
stent-jacket can be inserted through a single incision, the need
for a second procedure to allow sufficient time for the necessary
strength of adhesion to develop before the stent-jacket can be
inserted is sought to be avoided. When the malacotic condition is
less extensive, stays can be coated with tissue infiltration and
bonding agents such as delineated in the section below entitled
Medication-coated Miniballs, Stays, and Prongs with a
Heat-activated (-melted, -denatured) Tissue Adhesive-hardener or
Binder-fixative, among others.
[1733] If deeply situated and used with a stent-jacket having a
base-tube of intrinsically magnetized spring metal, then placing
the patient in a radiofrequency alternating magnetic field can be
used to accelerate bonding by warming the jacket once in position.
If not too deep, warming is by electrical blow drying. As the
initial retractive force required to overcome the stenosis or
collapse increases, the risk that the adventitia will delaminate
from the subjacent tissue increases as well. However, the mild
resistive force of stenting retraction should cause the smooth
muscle and connective tissue in a ductus that had stenosed to
strengthen.
[1734] Furthermore, whether the intrinsic strength of the wall will
eventually become sufficient to preserve the integrity of the wall
without any exogenous means of support, to reduce the risk of
inter- or intratunical delamination, various tissue hardener and
binder fixative agents, to include cements, protein solders and the
use of implants with surface textures devised to encourage tissue
infiltration are provided. Coating the internal surface of the
base-tube with a cement that becomes inelastic upon setting should
be disallowed as reducing the freedom of expansion and contraction.
The moisture barrier-coated viscoelastic polyurethane foam lining
and in some instances, the addition of a soft gauze lining as an
additional antimigratory measure also contribute to mobility.
[1735] Furthermore, given the adaptive responses exhibited by many
ductus, notably arteries (see, for example, Dirsch, O., Dahmen, U.,
Fan, L. M., Gu, Y. L., Shen, K., Wieneke, H., and Erbel, R. 2004.
"Media Remodeling--The Result of Stent Induced Media Necrosis and
Repair," Vasa 33(3):125-129), depending upon the medical condition
and previous treatment of the artery, any patenting restraint at
the interface separating the adventitia from the outer surface or
magnetic field-projecting layer in the base-tube is likely to
prompt a compensatory strengthening of the ductus. Some
strengthening of the smooth muscle to less than a hyperplastic
extent is desirable. Patenting restraint will tend to be less at
the side-slit or side-slot. A through-thickness magnetized
stainless steel base-tube can be made thinner to avoid encroachment
on neighboring tissue, and lined with polyurethane foam, is less
likely to provoke local adverse tissue reactions.
[1736] Strengthening should result in some thickening of the wall
phenotype but not a substantial proliferative hyperplasia (see, for
example, Richard, M. N., Deniset, J. F., Kneesh, A. L., Blackwood,
D., and Pierce, G. N. 2007. "Mechanical Stretching Stimulates
Smooth Muscle Cell Growth, Nuclear Protein Import, and Nuclear Pore
Expression Through Mitogen-activated Protein Kinase Activation,"
Journal of Biological Chemistry 282(32):23081-23088; Qu, M. J.,
Liu, B., Wang, H. Q., Yan, Z. Q., Shen, B. R., and Jiang, Z. L.
2007. "Frequency-dependent Phenotype Modulation of Vascular Smooth
Muscle Cells Under Cyclic Mechanical Strain," Journal of Vascular
Research 2007 44(5):345-353). The stent-jacket lining and miniballs
or stays can be coated with counterproliferative medication (see,
for example, Sakamoto, K., Murata, T., Chuma, H., Hori, M., and
Ozaki, H. 2005. "Fluvastatin Prevents Vascular Hyperplasia by
Inhibiting Phenotype Modulation and Proliferation Through
Extracellular Signal-regulated Kinase 1 and 2 and p38
Mitogen-activated Protein Kinase Inactivation in Organ-cultured
Artery," Arteriosclerosis, Thrombosis, and Vascular Biology 25(2):
327-333).
[1737] The material of the internal surface of the base-tube can be
treated to suppress sliding migration along the ductus by
incorporating a frictional base-tube lining that is textured or
made of gauze, for example. The application of a tissue sealant to
the internal surface of the base-tube, such as to seal a
perforation left by a fistula, can prevent movement between the
ductus and base-tube at and around the bond, and is likely to
disintegrate according to the turnover rate of the tissue; the
approach is can be used to gain time where the temporary fixation
would allow healing. Where potentially fistulizing friction against
an adjacent ductus is a possibility, the stent-jacket with bar
magnets if any can be encapsulated as perforated within a tissue
compatible and enzyme resistant cushioning coat of a rubbery or
plastisol-like material.
[1738] A soft silicone rubber or thermoplastic polyurethane, such
as Bayer Material Science Texin or Desmopan.RTM. can also
incorporate ferrous particulate to expedite warming as well as
chemically isolate the base tube. Such a coating can be formulated
to adjust the elasticity of the base-tube. At a curing temperature
of around 350 degrees Fahrenheit, such a coating is applied at well
below the Curie temperature of the magnets, which depending upon
the exact lanthanoid, is around 590 degrees Fahrenheit. Although
durable materials are used for the base-tube, in a young patient,
such a barrier can be used to further forestall any breakdown and
the formation of base-tube microfractures that would progressively
reduce its resilience, and if containing embedded particles, for
example, break the chemically isolating seal.
[1739] Such an outer coating can also be used to a. Cushion the
already rounded edges of the magnets, further protecting against
abrasive injury, b. Whether to cover the entire surface of the
stent-jacket as by adding barium sulphate to the resin, or limited
to its ends, side-slit, and/or magnets as with tantalum,
incorporate radiological contrast dye markings, c. Contain embedded
lanthanoid or radiation shielding particles such as tungsten, and d
Enhance adhesion to the internal surface of a lining, such as one
consisting of a solid protein solder tissue adhesive as addressed
below in the section entitled Specification of Cyanoacrylate Tissue
Sealants and Bonding Agents and/or a double-wedge lining as
addressed below in the section entitled Double-wedge Stent- and
Shield-jacket Rebound-directing Linings.
[1740] The linings prescribed herein are sufficiently compliant
circumferentially that an internal suface need not be made of a low
friction fluoropolymer, for example, to accommodate the free
movement of the ductus when changing in gauge as would bode against
antimigratory stability. Implantable coatings continue to be
advanced (see, for example, Ding, N. 2007. "Poly(vinyl Acetal)
Coatings for Implantable Medical Devices," U.S. Pat. No.
7,294,329). The restorative force of the stent-jacket base-tube,
which is the product of the intrinsic elastomeric properties of the
material and its thickness, or if a coextrusion, the combination of
materials and thicknesses, is selected for close compliance with
the pulse or smooth muscle action passing through the ductus and
not so resistant to such action that the margins (end rims) dig
into the outer surface of the ductus. In some instances,
chain-stents are used to achieve this action.
[1741] The stent-jacket lining must possess the elasticity to yield
at the point of impact of the miniballs when placed at the correct
angle at the correct exit velocity prior to implantation and not
present a mechanical or chemical irritant on its inner surface or
at its margins. Linings to protect against perforations resulting
from errors in these factors are addressed below in the section
entitled Double-wedge Stent- and Shield-jacket Rebound-directing
Linings. The avoidance of the lumen made possible by using stays
averts significant sequelae (see, for example, Tesfamariam, B.and
DeFelice, A. F. 2007. "Endothelial Injury in the Initiation and
Progression of Vascular Disorders," Vascular Pharmacology
46(4):229-237). Stay insertion tools are designed to allow stay
insertion with minimal if any compression of the ductus as would
bend the intima. The deformation in the cross section of a vessel
by atheromatous tissue that can promote thrombogenic turbulent flow
is reduced by magnetic traction to the circular internal surface of
the stent-jacket.
[1742] The base-tube of an extraluminal stent-jacket can be punched
or slotted to expose the outer surface of the ductus to its normal
environment or to reduce the resilience of a base-tube when
encapsulated or equipped with a lining, or to provide clearance for
a portion of the tunica fibrosa or adventitia, for example.
Ideally, both the base-tube and encapsulating layer added to the
base-tube to provide a softer outer surface and unitize the magnets
and base-tube consist of materials established to remain inert in
the internal environment and free of adverse tissue reactions, as
addressed above in the section entitled Tissue Acceptance of
Ductus-Intramural Implants. Should the underlying base-tube be
implicated in adverse tissue reactions, then rather than to expose
the base-tube, the outer layer is applied after apertures or
perforations have been punched or cutouts for nerves or vessels
nibbled away. Suitable materials are addressed below in the section
entitled Internal Environment-resistant Base-tube Polymers,Metals,
and Combinations Thereof.
[1743] A side-slit or full-round stent-jacket is shown in FIGS. 2
thru 5, 7 and 9, the parts thereof enumerated in the section above
entitled Description of the Preferred Embodiments. A full round
stent-jacket is used when the vessel or duct can be completely
encircled, allowing miniballs or stays to be subadventitially or
medially implanted and retract the ductus wall entirely about the
periphery. When stenosis or collapse is eccentric, a full found
stent-jacket is still placed as countermigratory. A partial
stent-jacket, or partially round or side-slotted stent-jacket,
consists of the same parts with a side-slit widened as a slot, and
is shown in FIG. 6 with a perforated base-tube. When the side-slot
is used to avoid needlessly dissecting subjacent tissue such as to
straddle a running attachment, for example, the tissue interposed
in the side-slot stabilizes the jacket. Other countermigratory
measures include, as necessary, side-straps, end-ties, and
nonsliding linings.
[1744] In the trachea, for example, depending upon the suitability
of a stent-jacket or chain-stent over the affected segment,
subcutaneous or suprapleural patch-magnets, as addressed below in
the section entitled Subcutaneous, Suprapleural, and Other
Organ-attachable Clasp- or Patch-magnets, can be used to retract
miniball or stay implants. Tangential traction is avoided through
radial alignment of the subadventitially or medially placed
miniballs or stays and the bar magnets mounted about the base-tube.
A benefit in the use of an intrinsically magnetized base-tube is
the radial neutrality that eliminates any need for radial
alignment, making such a base-tube more convenient to place when
retraction is to be eccentric (not radially symmetrical).
[1745] With a discretely magnetized stent-jacket, radially aligning
more sparsely placed subadventitial or medial miniballs or stays
with the bar magnets mounted about the base-tube minimizes
nonradial or tangential vectors. To reduce the risk of tunical
delamination and pull-through, the radially aligned magnets should
exert the least functional tractive force as determined by in situ
testing, addressed below in the section entitled Testing and Tests.
An advantage of intrinsically or quasi-intrinsically magnetized
stent-jackets, as described above in the section entitled Types of
stent-jacket, is uniform magnetic traction over the entire surface
of the stent-jacket. In an intrinsically magnetized stent-jacket,
the magnetic tractive force is due to the magnetic mass and domains
of the ferromagnetic material, which in quasi-intrinsically
magnetized stent-jackets, is contained within the particulate
embedded in the matrix.
[1746] Whether contained within particles, domains are in effect
many more and more closely juxtaposed permanent magnets that
project force with a uiniformity that is unapproachable using
discrete bar magnets. The uniformity of magnetization in a
quasi-intrinsically magnetized stent-jacket depends upon the
density and distribution pattern of the embedded magnetized
particulate. A large number and proximity of poles reduces the
magnitude of the tractive force and minimizes the concentration of
traction on those ductus-intramural implants radially axial to each
pole and circumjacent thereto. Except in exceptional circumstances
where the tractive force is intended to be focused, this eliminates
the need to radially align the magnetic poles to the implants,
making such a base-tube more convenient to place.
[1747] If lesion eccentricity or a malacotic condition recommend
avoiding implantation in a certain arc or segment, then that area
is not implanted, and the use of a stent-jacket which more
uniformly distributes a mild tractive force, that is, one
intrinsically or quasi-intrinsically magnetized, is used to reduce
pulling at the affected area by the adjacent implants. Absorbable
base-tube and matrix materials with the mechanical properties
needed are addressed below in the section entitled Absorbable
Base-tube and Stent-jacket, Miniball, Stay, and Clasp-magnet Matrix
Materials. In any stent-jacket or base-tube, sufficiency of
resilience denotes synchronous expansion and contraction with the
ductus, hence, continuous apposition of ductus and jacket with
countermigratory contact and constancy of tractive force
maintained.
[1748] While expansion inserts, as addressed below in the section
entitled Expansion Inserts Absorbable, Meltable, and Comminutable
for Time-discrete Decremental Contraction of Stent-Jackets, have
been shown as applied to side-slit, or full-round stent-jackets,
these are no less applicable to side-slotted, or partially-round
stent-jackets. In using a multiple barrel-tube barrel-assembly,
less than fully circumferential discharge can be accomplished by
blanking out one or more of the barrel holes in the rotary magazine
clip. The manufacture of barrel-assemblies with muzzle-heads having
eccentric muzzle-ports or muzzle-ports limited to a certain arc
about the periphery is negated by the ability of the turret-motor
to rotate the muzzle-head with or without multiple
muzzle-ports.
[1749] When diagnosed early, a nonmagnetic loosely woven spandex or
perforated resilient polymer based stent-jacket with a side-slit
and stretch compliant side-straps as shown in FIG. 15 can be
applied to an incipiently aneurysmal abdominal aorta, for example.
A jacket of this kind applied thus are ancillary to the central
content addressed herein. The object in such treatment is to
actively truncate enlargement preserving nonthrombogenic laminar
flow rather than to passively watch and wait, depending upon the
cause, allow the vessel an opportunity to recover, and avoid the
eventual need for insertion of an endoluminal stent-graft with the
risks of an endoleak, kinking, thrombosis, angulation, and
migration, or excision and insertion of a synthetic graft (The
Merck Manual of Diagnosis and Therapy, 18th edition, page 740).
[1750] Usually associated with distributed vascular disease, early
correction should not affect a propensity for spread or the
separate appearance of an iliac or femoral aneurysm. A
circumvascular jacket is not susceptible thus, leaves the lumen
free of a foreign object, need flex to a lesser extent, can have
small side branches should the aneuraysm extend to the renal
arteries, and is removable. It has been demonstrated in an
endovascular stent-graft bifurcated for extension down into the
iliac arteries that the ability to flex improves the outcome of an
abdominal aortic aneurysm (Arko, F. R., Lee, W. A., Hill, B. B.,
Cipriano, P., Fogarty, T. J., and Zarins, C. K. 2001. "Increased
Flexibility of AneuRx Stent-graft Reduces Need for Secondary
Intervention Following Endovascular Aneurysm Repair," Journal of
Endovascular Therapy 8(6):583-591). Flexion should not be confused
with laxity that allows continued enlargement of the aneurysm, as
addressed above in section I1 entitled General Considerations to
Include Insertion.
[1751] Such nonmagnetic wrap-surround stent-jackets can be
longitudinally split and optionally connected together to straddle
points of flexion. Peripheral arterial aneurysms are not reported
to appear at points of flexion. In a magnetic stent-jacket, the
resilience of the base-tube for longitudinally mounting the tiny
bar magnets varies with the material and its dimensions. The tubing
can be simple or compound (coextruded), expanding the range of
properties to include the restorative force. The addition of an
internal layer within a stent-jacket to moderate rebound when the
stent-jacket is placed prior to discharge in order to prevent
perforation, for example, is addressed below in the section
entitled Sequence of Stent-jacket Placement and Implantation.
[1752] Means for preventing the escape of a miniball are addressed
below in the sections entitled Multiple Radial Discharge
Barrel-assemblies with One- to Four- or More-way Radial Discharge
Muzzle-heads and Embolic Trap Filter in Radial Discharge
Muzzle-heads for Use in the Vascular Tree. Prior to placement about
the implanted site, the inner surface of the stent-jacket can be
wetted with a coagulant, antibiotic, anti-inflammatory, tissue
reaction counteractant, or other medication, the use of an adhesive
generally temporary. Unless made of an intrinsically magnetized
material, one encapsulated within a soft bioinert plastic resin
that sufficiently blunts the exposed edges of the bar magnets, or
the latter with embedded magnetized particulate, the edges the
magnets are rounded prior to plating and replating, or plating and
Microfusion.RTM..
[1753] The latter is a proprietary plasma-based ion deposition or
physical vapor thin film vacuum coating form of metastable phase
synthesis available from Implant Sciences Corporation, Wakefield,
Mass. Replating or a process such as sputtering or
Microfusion.RTM., for example, can be used to cover over any
microfractures that remain following plating, as well as to
internsify radiopacity (see Sahagian, R. 1999. "Critical Insight:
Marking Devices with Radiopaque Coatings," Medical Device and
Diagnostic Industry Magazine, Canon Communications, May 1999
available at http://www.devicelink.com/mddi/archive/99/05/011.html
and http://www.implantsciences.com/pdf/orthodontic.pdf).
[1754] Microfusion.RTM. or a similar process is an outgrowth of
nonplasma (discrete, directed beam) ion deposition (see, for
example, Hirvonen, J. K. 1991. "Ion Beam Assisted Deposition,"
Material Science Reports 6 (6):215-274; Nastasi, M. A., Mayer, J.
W., and Hirvonen, J. K. 1996. Ion-Solid Interactions: Fundamentals
and Applications, New York, N.Y.: Cambridge University Press). Both
plating and ion deposition are convenient methods for bringing
implants up to a certain mass to adjust the discharge momentum, for
example. Compared to replating, Microfusion.RTM. or a similar
process generally allows equal if not finer control over deposition
thickness, hence, mass.
[1755] Such a process can be used for the primary object of
providing high radiopacity markings in lieu of painting or banding,
the inclusion in components of a metal powder based paint such as
barium or tungsten, electroplating, chemical vapor desposition,
high vacuum thin film coating, cold process physical vapor
deposition, plasma vapor, or sputter-coating, for example, wherever
the marking of components described herein is necessary. A ductus
that varies in diameter or treatable condition along its length can
be treated with a sectional or chain stent-jacket, which can also
incorporate impasse-jackets as necessary, mentioned above.
[1756] Such a train consists of distinct unit jackets, so that
ordinarily, a change in diameter of the treated ductus is not
treated with a continuous jacket of flaring diameter but sub-stents
of different diameter at intervals. Where a continuous jacket is
necessary, one longer with a thicker moisture barrier-coated
viscoelastic polyurethane foam lining is used. The rate of change
must be high to require that the thickness of the foam lining be
cut to change likewise. Atheromatous disease tends to favor entries
into bifurcations and openings to side branches, or ostia, as
points of increased shear stress. To clear a side-branch, the
stent-jacket expansion slit is nibbled away with complementary
semicircles into the opposing edges.
[1757] This is generally done at the time of insertion when the
jacket can be placed against the ductus to confirm the diameter and
position of the hole required. To clear a bifurcation, a separate
stent-jacket is positioned about each branch; however, when to
properly fit these makes it necessary, a Y-shaped jacket with a
Y-shaped side-slit is used. Similarly, stent-jackets can be made in
shapes other than cylindrical, such as one tee-shaped to encircle a
trunk and branch. Silicone-urethane copolymers are antioxidative,
elastic, and resilient at body temperature as to exhibit `memory,`
have a coefficient of friction that combined with the other
countermeasures to be described are consistent with resistance to
migration, and have already met the federally mandated criteria for
implantable material.
[1758] Bioinert polymeric materials suitable for the base-tubes of
stent-jackets with magnets mounted to the outer surface are
numerous, and include silicone, expanded polytetrafluororethylene,
polyfluoroethylene, other fluoropolymers, polyetherurethane,
polycarbonateure-thane, polysiloxaneurethane, silicone-polyurethane
copolymers and hydrogenated poly(styrene-butadiene) copolymer.
Recent improvements in these materialssuch as those addressed below
in the section entitled Internal Environment-resistant Base-tube
Polymers, Metals, and Combinations Thereof mean that replacement
should not become necessary for years if ever. Clearance by the
neighboring anatomy permitting, varying the restorative force
required to fit the ductus treated is readily accomplished by
changing the material or wall thickness of the tubing.
[1759] I3. Order of Stent-Jacket Placement
[1760] I3a. Circumstances Recommending the Use of a Shield-Jacket
or Preplacement of the Stent-Jacket
[1761] An absorbable (temporary) or nonabsorbable shield-jacket,
stent-jacket, or impasse-jacket with absorbable shield can be
placed prior to initiating discharge. In addition to serving as a
physical barrier or shield, the jacket can be made remotely
heatable, allowing the ductus to be warmed, the release or uptake
of a drug to be accelerated, or the jacket to be disintegrated on
demand, for example. Preplacement of the jacket can serve to
avert:
[1762] 1. Perforation (the penetration through-and-through) or
puncture (partial penetration) through the ductus wall. 2. The
striking of a vulnerable structure, such as a nerve, ganglion, or
vessel near to the treated ductus on perforation or by
approximation of the adventitia at the point where the lumen wall
has been struck or punctured within.
[1763] 3. Rebound of the miniball to a nonfunctional
(nonretracting) location or even the lumen, avertable through the
use of a stent-jacket with double-wedge lining described below in
the section entitled Double-wedge Stent- and Shield-jacket
Rebound-directing Linings; or to
[1764] 4. Counteract abrupt closure with or without vasospasm, or
reflexive contracture, whether due to endothelial dysfunction,
reflexive of ballistic insertion, or both when vasodilators alone
cannot be depended upon; or
[1765] 5. Provide a backing against which the adhesive or tissue
hardening agent injected wall can be compressed by the injecting
barrel-assembly or radial projection catheter within the lumen made
necessary by internal weakening or delamination within the wall of
the ductus. The prevention of perforation is most important when
the lumen contents are septic, as in the colon or an artery when
the blood is infected or suspected to transport metastatic cells
shed by a primary tumor. The risk of perforation is much less with
stays, which are inserted from outside the ductus.
[1766] Other reasons for placing the stent-jacket prior to
discharge are to:
[1767] 6. Take advantage of the outward tractive force exerted by
the stent-jacket in order to prevent the dislodging of an implanted
miniball, especially when the need arises to pass an implanted
miniball with the tractive recovery electromagnets energized.
[1768] 7. Take advantage of a tantalum coated stent-jacket as an
imaging marker of high radiopacity to reduce any difficulty in
locating and observing the work site.
[1769] 8. Preclude a weakening of the luminal wall by implantation
sufficiently dense, such as miniball discharge under automatic
positional and discharge control to evenly distribute the field
force, that if eccentric could progress to a saccular, or if
circumferential, a fusiform aneurysm.
[1770] 9. Magnetically attract drug carrier nanoparticles or
magnetically susceptible microspheres at any time after
placement.
[1771] 10. Shield the surrounding tissue from radiation when the
stent-jacket includes radiation shielding and is used to support
magnetically targeted radioisotope-bound drug carrier magnetically
susceptible nanoparticles or microspheres.
[1772] 11. Cinch about the ductus with a jacket having side-straps,
thereby reducing its motility, allowing greater discharge accuracy;
and
[1773] 12. To allow the use of an oversized muzzle-head for
compression under heat supplied by a nose radiofrequency probe or
other type thermoplasty window when used with a preplaced
stent-jacket to fuse the laminae, when imaging confirms
delamination in the wall of the ductus (see, for example, Kaplan,
J., Barry, K. J., Connolly, R. J., Nardella, P. C., Hayes, L. L.,
and 4 others 1993. "Healing after Arterial Dilatation with
Radiofrequency Thermal and Nonthermal Balloon Angioplasty Systems,"
Journal of Investigative Surgery 6(1):33-52; Resar, J. R., Wolff,
M. E., Hruban, R. H., and Brinker, J. A. 1993. "Endoluminal Sealing
of Vascular Wall Disruptions with Radiofrequency-heated Balloon
Angioplasty," Catheterization and Cardiovascular Diagnosis
29(2):161-167; Barry, K. J., Kaplan, J., Connolly, R. J., Nardella,
P., Lee, B. I., Becker, G. J., Waller, B. F., and Callow, A. D.
1989. "The Effect of Radiofrequency-generated Thermal Energy on the
Mechanical and Histologic Characteristics of the Arterial Wall in
Vivo: Implications for Radiofrequency Angioplasty," American Heart
Journal 117(2):332-341).
[1774] The increase in susceptibility of an already diseased ductus
wall to aneurismal failure following an atherectomy and/or the
placement of ductus intramural implants is unpredictable; however,
such risk is minimized by preplacement of the stent-jacket, which
can precede not only ballistic (but not stay) implantation, but
angioplasty. This condition is most prominent when miniballs are
implanted in a close formation under machine control precisely to
achieve a uniform distribution of the tractive force, in which case
an intrinsically or quasi-intrinsically magnetized stent-jacket is
preplaced as the complement to field uniformity. In such instances,
the foam lining should be rather firm to support the weakened wall.
Outward failure in the form of delamination is likewise
discouraged.
[1775] An endoluminal stent is incapable of providing inward
constraint, and since it must exert radially outward force to avoid
migration, would promote failure. The multiple reasons for
preplacement notwithstanding, in locations when perforation is of
less concern, placing the jacket only after discharge eliminates
the possibility of rebound, which may require extraction,
increasing procedural time. Thus, preplacement of a stent-jacket
may serve purposes related or unrelated to extraluminal magnetic
stenting; depending upon the application, such placement can be
accomplished where no ductus-intramural implants are to be placed,
or at any time before or after ductus-intramural implants are
placed, whether drug or radiation miniballs or magnetically
susceptible nanoparticle-bound radiation drugs, for example,
introduced into the bloodstream, for example.
[1776] Stent-jacket placement can be followed by the infixion of
miniballs or introduction of drug carrier nanoparticles, for
example, immediately or at any later date. When part of a magnetic
stent, this makes possible the targeting of followup adjuvant
medication, for example, at any time without the need for any
additional measure. A temporary (absorbable) stent-jacket placed
solely to shield against a perforation or punching injury is best
eliminated prior to withdrawal by accelerating dissolution through
the use of the heating elements in the muzzle-head, to include
heat-windows. The preplacement of a more strongly magnetized or
magnetically susceptible stent-jacket reduces the risk of miniball
rebound into the lumen, making the preplacement of a radiation
shielded stent-jacket a valuable precaution when magnetically
targeted radioisotope-bound drug carrier nanoparticles or
radioactive stays or miniballs are used.
[1777] Due to the small diameter of miniballs and the intrinsic
ability of most ductus to seal a perforation quickly, a
perforation, should it occur, should seldom pose a problem.
Absorbable stent- and impasse-jackets leave behind the moisture
barrier-coated viscoelastic polyurethane foam lining as an
innocuous vestige. Those that include radiation shielding can be
made fully absorbable, as addressed above in the section entitled
System Implant Magnetic Drug and Radiation Targeting, among others.
Melting a solder coating applied to a ductus-intramural implant may
require heat shielding to protect the surrounding tissue, for
example. Preplacement of a stent-jacket can therefore be used to
shield surrounding tissue from an injurious temperature or
radiation, whether along a certain arc or entirely about the
substrate ductus.
[1778] In arteries, however, platelet blockade will have been
administered to avert the risk of thromboembolism due to the
rupture of vulnerable plaque or the punctures at the points of
miniball entry, and the peak in blood pressure with each systole
means that a perforation could result in bleeding (extravasation,
exsanguination) that must be prevented. A stent-jacket placed prior
to miniball discharge is usually intended to block or shield
against any miniball that would perforate through the outer
fibrosal or adventitial tunic and into the surrounding tissue or
body cavity. Should a miniball perforate, it becomes trapped in the
foam lining, and embedded therein, will not irritate the ductus.
More often, the stent-jacket absorbs much of the impact so that a
perforation is prevented.
[1779] When higher discharge velocities are required predisposing
toward rebound, a prepositioned double-wedge-lined stent-jacket,
addressed below in the section entitled Double-wedge Stent- and
Shield-jacket Rebound-directing Linings, is used to deflect the
miniball toward a functional ductus-intramural location rather than
reentry into the lumen. The release of blood into the lining of the
stent-jacket as the result of a perforation is unlikely to exert
any significant or persistent alteration in its mechanical
properties. Minimizing the entry of blood into the lining of a
prepositioned stent-jacket will depend upon the condition of the
blood due to the administration of an anticoagulant or platelet
blockade for the procedure. If a concern, then prior to placement,
the lining is wetted or coated with a coagulant, such as chitosan
(Celox.RTM., Medtrade Biopolymers Incorporated, Crewe, England)
and/or a synthetic derivative of volcanic rock (QuikClot.RTM.,
Z-Medica Corporation, Wallingford, Conn.). The same applies whether
the stent-jacket is double-wedge lined.
[1780] I3b. Sequence of Stent-Jacket Placement and Implantation
[1781] Perforation with continued travel into the surrounding
tissue or cavity should rarely if ever result in a longer term
adverse consequence; however, the transaction of a nerve fiber can
cause short-term numbness or partial dysfunction. Weighing this
risk in context and the relative benefit and detractions in using a
protective shield during discharge must be on a case by case basis.
Preplacement of the stent-jacket does not apply to the use of
stays, which inserted from outside the ductus through the
adventitia, must be placed before the stent-jacket, which if placed
first would block access. When the only reason prompting
preplacement is to avoid a perforation, the use of stays may be
considered. When another reason, such as to be able to
noninvasively warm the substrate (treated) ductus by induction
heating the stent-jacket before initiating or during discharge
implantation, then ab initio, stays have been discounted.
[1782] However, a stent-jacket applied after stays have been
inserted can be heated at any later date. Various circumstances
recommend placing the stent-jacket before initiating miniball
discharge. These include preventing perforations, reducing the risk
of punctures through the intima that result in continued travel
between separated layers through the ductus wall by applying
temporary compression reducing the extent of any inter- or
intralaminal separations as might occur, and compensating for
weakness or a malacotic condition predisposing to the development
of an aneurysm; the stent-jacket may be placed first to
structurally support a segment weakened by pathology, and in so
doing, shield against perforations through the segment. Acting on
the basis of in situ testing and careful examination of the initial
discharge, the penetrability of the lesioned and adjacent areas to
be implanted dictate the exit velocities appurtenant of each and
the need to preplace the stent-jacket.
[1783] The preplacement of a stent-jacket, addressed above in the
section entitled Circumstances Recommending the Use of a
Shield-jacket or Preplacement of the Stent-jacket, can also serve
to insulate and increase the conduction of heat delivered by the
barrel-assembly heat-windows or heated gas delivery connections,
such as when used to accelerate the setting of a surgical cement or
flow a solid protein solder coating on a miniball. If it
incorporates continuous ferrous material, the stent-jacket can be
independently heated noninvasively by heat induction by placing the
patient in an alternating magnetic or electromagnetic field, as
addressed above in the section entitled Implants that Radiate Heat
on Demand, among others. To the extent possible, the aim should be
to use components that are absorbable and extracorporeally
(noninvasively) controllable, or `smart.`
[1784] When a perforation could result in the striking of a
ganglion or the perforation and entry into the lumen of a
neighboring vessel, the stent-jacket should be placed prior to
implantation. While an effective method for preventing such
eventualities, when it obstructs a clear view of the work area,
preplacement is not recommended. A stent-jacket to treat a radially
asymmetrical or eccentric lesion along a ductus wall will usually
limit magnetization to the arc affected. Unless the need to
preplace such an eccentric stent-jacket is compelling, placement is
deferred until after the miniballs have been placed. Even when the
stent-jacket is preplaced, so long as the strength of magnetization
is not high, the muzzle-head is not significantly smaller in
diameter than the lumen, the arc to be implanted is not too
compressed to be implanted, and only the treated arc is to be
implanted with miniballs, the attraction of the muzzle-head, which
contains the ferromagnetic cores of the turret-motor and recovery
electromagnets, toward this arc is seldom a problem.
[1785] A drug avoidance means for reducing the intensity and radial
excursion of intrinsic movement in the lumen wall that interferes
with accuracy is to preplace the stent-jacket, if necessary, with
the belt-straps temporarily adjusted to retain the side-slit flush.
Noninvasive heating of a stent-jacket by heat induction in an
alternating magnetic or electromagnetic field to melt a coating
such as an adhesive or release and accelerate the uptake of a
therapeutic substance such as a drug requires that the stent-jacket
have already been put into position. A stent-jacket preplaced to
guard against perforation when nonstenting medication miniballs are
used should be absorbable, preferably, absorbable on demand by
means of noninvasive heat induction when desired, as addressed
above in the section entitled Implants that Radiate Heat on Demand,
among others.
[1786] When the miniballs include a radioactive seed, the jacket
can also include an absorbable radiation shield, as addressed above
in the section entitled Radiation Shield-jackets and Radiation
Shielded Stent-jackets Absorbable and Nonabsorbable. The need to
control miniball rebound is determined by applying the delamination
susceptibility testing procedure provided below in the section
entitled Testing and Tests, and one means for achieving such
control addressed above in the section entitled Double-wedge Stent-
and Shield-jacket Rebound-directing Linings. The risk of
delamination between or within tunics is increased when miniballs
are discharged in close proximity by an automatic positional
control system. While perforation (through-and-through penetration
and extraductal emergence) of a miniball is always to be avoided,
the diameter of the miniballs is so small that a perforation does
not result in significant injury.
[1787] Due to the small diameter of miniballs, perforations are
spontaneously sealed immediately by proteinaceous exudation,
endoplasmic or serous, axons regenerate at about one millimeter per
day, nerve cell nuclei have redundancy sufficient to overcome the
small scale damage, and spillage from the gut, addressed in the
section below entitled Uses of Impasse-jackets, is slight and
manageable. Larger diameter miniballs are inappropriate for use in
arteries; if used where coagulation expedites the sealing of a
perforation (hemostasis), preplacement of a stent-jacket allows
doses of platelet blockade and anticoagulant to be reduced thus
reducing the risk of unwanted bleeding Application of a topical
coagulant to the internal surface of the jacket or to the exterior
of the vessel exerts no effect upon the concurrent circulation of a
platelet blocker or anticoagulant as to reduce the risk of
thrombogenesis within the lumen. The permanent lodging within the
foam lining of a stent-jacket or tissue of a sterile bioinert
miniball is innocuous.
[1788] Embolization by entry into the circulation is prevented by a
number of means using magnetic arrest and recovery, such as
delineated above in section 4g entitled Emergency Recovery of
Miniballs and Stays. The propensity of the layers within the ductus
wall for separation can be predetermined through the test described
below in the section entitled In Situ Test on Extraluminal Approach
for Intra- or Inter-laminar Separation (Delamination). When
proximity to a vulnerable neighboring structure such as a ganglion
does dictate, perforation is prevented from leading to the puncture
of the neighboring structure that would ensue were the perforation
not trapped within the moisture barrier-coated viscoelastic
polyurethane foam lining outside the adventitia. In such use, the
innermost moisture barrier-coated viscoelastic polyurethane foam
lining of the stent- or shield-jacket exhibits the yielding or
nonresilience to minimize rebound, which could result in the entry
of a miniball into the lumen as well as the shape memory to protect
the vasa and nervi vasorum.
[1789] A magnetic stent-jacket also assists in minimizing if not
eliminating rebound and in retaining the implanted miniballs in
position by magnetic traction; from this standpoint, a stent-jacket
functions as a less powerfully magnetized impasse-jacket. Another
use for placing the jacket first is to damp discharge-induced
asymmetrical jerking of the ductus. Provided the muzzle-head
contacts the lumen wall round and about, even eccentric discharge,
or discharge not force counterbalanced, produces no appreciable
abrupt accelerations (jerking, recoil) as might dislodge a properly
seated miniball or shake loose one trapped between the muzzle-port
and the lumen wall. In this circumstance, to reduce the risk of ing
implanted miniballs, the stent-jacket is placed prior to
withdrawal. Yet another reason for placing the stent-jacket prior
to initiating discharge is to take advantage of the site-marking
radiopacity of a stent-jacket coated with contrast, such as of
tantalum.
[1790] When it is desired to chill a ductus with a stent-jacket
preplaced to prevent a perforation or reinforce a weak portion of
the wall of the ductus, for example, during transluminal ballistic
discharge, then chilling must be provided by the barrel-assembly.
This can be accomplished with a capless cooling catheter, as
addressed below in the section entitled Cooling Catheters
(Temperature-changing Service-catheters, connected to a cold air
gun or liquified gas cartridge as addressed below in the section
entitled Turret-motor Operational Modes, that discharges cold air,
another gas, or water against the nose heat-window of an
edge-discharge barrel-assembly). Whether implanted with miniballs
or stays, when the ductus is not yet mantled about, cold line
access can be from outside the vessel through the same incision as
will be used to insert the stent-jacket.
[1791] Even though the implants may be miniballs, a stay insertion
tool with lamp or endoscope and cold air line attached, as
described below in the section entitled Binding of Lines and Cables
Alongside the Stay Insertion Tool, can be inserted through the
incision to effect chilling. Whether this should preclude placement
of the stent-jacket prior to discharge must be left to clinical
judgment. A stent-jacket placed prior to discharge will safely trap
within its lining outside the adventitia a miniball that perforates
due to an unexpected deviation in wall strength. If the
stent-jacket is more strongly magnetized, a miniball that does not
fully puncture through the adventitia will be held where the
tractive electromagnets can be used to recover it rather than
allowed to rebound into the lumen.
[1792] In the vascular tree, an impasse-jacket positioned
downstream to will avert entry into the circulation of a miniball.
Miniballs are generally small in diameter as not to embolize tissue
without collateral circulation and are readily retrievable, as
addressed above in section 4g entitled Emergency Recovery of
Miniballs and Stays and below in section X2a(1) entitled
Midprocedural Interception and Recovery of a Miniball Entering the
Circulation, among others. That precaution taken, a stent-jacket or
a separate shield-jacket, addressed below in the section entitled
Nonmagnetized Base-tubes and Double-Wedge Shield-jackets, with a
double-wedge lining, addressed below in the section entitled
Double-wedge Stent- and Shield-jacket Rebound-directing Linings,
intended to redirect a rebounded miniball back into the lumen wall,
can eliminate the need for recovery.
[1793] Whether placed before or after discharge, wetting the
interior of the stent-jacket with a vascular hemostat, such as
vasopressin, epinephrine, or gamma-aminobutyric acid, and/or a
plasma coagulant, such as thrombin, will arrest bleeding from a
perforation that the systemic (circulating) anticoagulant and/or
platelet blockade administered would otherwise perpetuate. Whether
in direct stenting without ablation or angioplasty or following
ablation or angioplasty immediately or after an interval, disease
process induced circumferential eccentricities and longitudinal
inconsistencies (differences, nonuniformities) in the mechanical
properties of the ductus wall will include strength, elasticity,
and resilience.
[1794] When implantation is ballistic, the initial or tentative
settings for the airgun controls are determined by means of testing
addressed below in the section entitled Testing and Tests, with
confirmation of the settings as achieving the desired result by
means of test discharges. Since most lesions are eccentric and
manual control allows the procedure to be discontinued at any
moment to allow the results of each discharge to be evaluated for
perforations or delamination, the first few discharges are
triggered manually and examined whether discharge is to be manual
or thereafter accomplished at a high rate under machine control.
Testing discharges should be few but cover different arcs and
levels along the segment to be implanted. When only absorbable,
such as medicinal, miniballs are to be implanted, the dose will be
too small and the consequences in terms of trauma too
insiginificant to justify the use of a temporary shield-jacket.
[1795] In most cases, the exit velocity will not require adjustment
from the lowest effective setting; while in others, the need for
adjustment should be few. While a temporary shield-jacket or
stent-jacket can be used during either manual or machine discharge,
when testing reveals significant deviations in mechanical
properties with a propensity for an occasional perforation at the
lowest effective exit velocity, implantation discharge when
automatic at high density that would tolerate a few misses is
usually performed uniformly at that exit velocity with a temporary
shield-jacket or preplaced stent-jacket to take up any
perforations. If manual, then discharge is usually stopped and the
adjustment made as necessary.
[1796] When significant differences are noted, implantation should
be manual, allowing not only the exit velocity to be adjusted but
the miniballs to be varied in magnetically susceptible content,
keeping stent-jackets uniform in strength of magnetization reducing
the cost of production. By contrast with this discretionary
approach, conventional or endoluminal stents are radially
symmetrical, and except for the margins, longitudinally uniform, so
that even when the stent will yield beyond a certain resistance,
all portions of the lumen lining surrounding the stent are treated
nondifferentially. Using the various means described herein, the
condition of the lumen interior can be differentially treated, and
it is this capability that prompts detailed examination and
testing.
[1797] The availability of intravascular ultrasound (IVUS) to allow
evaluation of the vessel wall can serve as a valuable adjunct to
angioscopy, which allows evaluation of the lumen, except this will
generally add time to the procedure, albeit negligible. When
placing nonabsorbable miniballs, based upon the uniform appearance
of the lumen, the in situ test, and a test discharge that confirms
the airgun settings as correct, the risk and/or consequence of a
perforation is considered slight as not to warrant more detailed
examination, whether to use a temporary shield-jacket or preplace
the stent-jacket with hemostat-wetted lining is a clinical
decision. If the miniballs are absorbable such as medicinal so that
only a transluminal approach is necessary, then precautions such as
intravascular ultrasound and the use of any kind of jacket may be
dispensed with.
[1798] Since cytoplasm from the broken cells immediately runs into
the penetration path or trajectory, a pinhole-sized perforation
through the wall of an artery seals quickly without the precaution
of a hemostat-wetted jacket lining, even though a systemic platelet
blocker and/or anticoagulant and blood pressure-reducing medication
have been administered. In an open surgical field or when an access
incision has been made that allows the ductus to be visually
examined, most locations will allow a deliberate perforation to
confirm that sealing is quick. Unless immediately retrievable or
posing a risk of problematic enstonement, errant miniballs as may
have dropped into or landed in the pericardial space or a body
cavity remain innocuous as boinert and best disregarded.
[1799] More numerous eccentricities in the medical condition and
mechanical properties of the ductus wall can be dealt with without
the need to withdraw and reenter, irritating the entry wound by
changing the exit velocity and/or rotary magazine clip in the
airgun chamber to allow separate implantation into the differing
segments or arcs thereof. Each rotary clip can load a different
number, diameter, and/or type of miniballs for discharge together
as a shot-group, the turret-motor and the use of a barrel-assembly
with at least 3 barrel-tubes allows discharge in any radius, and
the rotary clips can be changed for each discharge, unneeded rotary
clip holes left out of the clip or plugged to conserve the
propulsive force.
[1800] That is, a barrel-assembly with a given number of
barrel-tubes can discharge a miniball into each sector or arc of
the surrounding lumen wall, where the sectors are defined according
to the circumferential spacing between the exit-holes. A four-way
barrel-assembly with exit-holes evenly spaced about the
circumference, for example, will discharge one miniball into the
center of each quadrant. Avoiding certain sectors requires only
that the corresponding hole in the shot-group on the rotary clip be
blanked out. With rotation by the turret-motor, traversing tighter
bends in the anatomy that would preclude bodily rotation or
torquing of the barrel-assembly as a whole can have little if any
effect on the ability to rotate the muzzle-head and therewith, the
angle of each successive discharge.
[1801] Unlimited choice of miniballs, rotary magazine clips, and
continuous variability in the exit velocity, combined with the
ability to rotate the muzzle-head eliminates any need for
barrel-assemblies with radially asymmetrical or eccentric
exit-holes. A four-way radial discharge barrel-assembly having
already been introduced into the lumen, for example, allows
changing from single or one-way miniball discharge to three-way or
triple discharge with each rotary magazine clip. This allows
successive circumferences to be implanted with unlimited
variability in the miniballs delivered, while adjusting the exit
velocity allows corresponding adjustment in the force of
penetration. The exit velocity can be adjusted for each shot group
within a rotary magazine clip but not each shot within a shot
group.
[1802] With multiple variables involved and ultimate control
unattainable, the ability to preplace a shield or stent-jacket to
protect against inadvertent perforations is a significant
consideration to justify a discharge by discharge discretionary
approach. If the number of spots that warrant testing is
prohibitive and changes must be frequent so that uncertainties
persist, such as then control over discharge should be manual with
a shield-jacket or preplaced stent-jacket in position.
Alternatively, the use of wide stays, which are not susceptible to
perforation, are inserted one at a time under the direct control of
the operator, and can differ in numerous ways from one to the
next.
[1803] Stays are also considerably less susceptible to
pull-through, are not subject to differences in the force required
to achieve insertion worthy of note, and thus avoid the
uncertainties associated with discharge implantation. When the
lumen is not characterized by numerous and marked differences,
machine control with a gravity fed chamber rather than rotary
magazine clips, as shown in the accompanying drawing figures of
interventional airguns, can lay down a dense formation of miniballs
of like diameter and mass at high speed to achieve uniform
distribution of the tractive force, especially when combined with
an intrinsic or quasi-intrinsic stent-jacket.
[1804] A proportion of these like sized miniballs can differ in
composition such as to include or consist of medication, thus
allowing uniformity in the delivery of a drug, for example, but not
uniformity at a level equal to coating every miniball alike. When
the wall of the ductus is too thin or tenuous to use either
miniballs or stays, a clasp-jacket is applied with the inner
surface coated with a surgical adhesive-sealant. Clasps that must
enter the lumen of a blood vessel because the wall has become so
thin must be nonthrombogenic, that is, polymeric, not metallic. In
this case, placement of the stent-jacket must follow immediately
rather than deferred to later date.
[1805] I3c. Sequence of Stent-Jacket Placement and Implantation in
Relation to Trap-Extractor (Recovery) Electomagnet Susceptibility
and Field Intensity
[1806] A more strongly magnetized stent-jacket may suddenly deflect
the muzzle-head even with the recovery electromagnets turned off,
and attempting to offset or balance the pull will prove difficult
and usually ineffective. Miniballs will also be accelerated by the
pull, and if a magnetized stent-jacket rather than a nonmagnetized
shield-jacket with double-wedge lining is used, the resilienc of
the materials of the double-wedge must the added acceleration on
approach and deceleration on rebound, as addressed below in the
section entitled Stent- and Shield-jacket Moisture barrier-coated
viscoelastic polyurethane foam Linings The procedure will be
simplified and reduced in duration when the permanent or absorbable
magnetized stent-jacket can be placed ab initio. The section below
entitled Nonmagnetized Base-tubes and Double-Wedge Shield-jackets
addresses jackets placed temporarily during discharge implantation
to protect against perforations.
[1807] To minimize abrupt deflections of the muzzle-head as would
detract from accuracy, the stent-jacket, usually one intrinsically
or quasi-intrinsically magnetized, is magnetized uniformly.
Intrinsic and quasi-intrinsic stent-jackets present a more dense,
evenly distributed, and radially symmetrical magnetization, making
these preferable to the use of discrete or spaced apart magnet type
stent-jackets when, albeit exceptional, magnetic strength of a
field intensity as would deflect the muzzle-head is required.
Eccentric retraction of a collapsed or stenosed lumen wall is
accomplished by placing the ductus-intramural implants in
conformity to the eccentricity without complementary eccentricity
in the stent-jacket also reduces the need for specially configured
stent-jackets to treat different eccentric conditions and the
greater cost to produce these.
[1808] The need for such strength is greater when the magnetization
is radially asymmetrical or eccentric as is associated with
placement to attract drug carrier nanoparticles in a ferrofluid
passing through the lumen against or into a lesion, and rarely if
ever with the degree of tractive force necessary to maintain
patency in a stenosed lumen. Intended to act over a distance, a
magnet-wrap or magnet-jacket usually incorporates more powerful
spaced apart magnets; however, it is not ordinarily used in
encircling relation to miniballs and therefore not transluminally
or intromission traversed by a muzzle-head. When encircled by more
powerful magnets, sudden displacement of the muzzle-head and
compression of the contact tissue will occur regardless how axially
centered or flush to the internal surface of the lumen wall the
muzzle-head appears fluoroscopically or otherwise
radiologically.
[1809] There are, however, circumstances in which it is preferrable
to place the stent-jacket before initiating discharge. For example,
the attractive force on the muzzle-head can be used to achieve
flush or even compressive placement of the muzzle-head against the
lumen wall, such as to flow and hold flush separated lamina pending
setting of a protein cement used as a tissue binder while heated by
a heat-window in the muzzle-head and/or heat induction of the
stent-jacket. In some cases, a stent-jacket with more powerful
separated magnets may be preplaced precisely to take advantage of
this detention at intervals, which is readily amplified to achieve
variability in the compressive force by adjusting the recovery
electromagnets in field strength and polarity as necessary.
[1810] Broadly, when discharge implantation is involved and the
pathology has produced marked differences in tissue penetrability
about the lumen wall, then the stent-jacket, which will present
magnetization conformant to this eccentricity, rather than
contributing yet another eccentricity by virtue of pulling at the
muzzle-head, should be placed after implantation. When offsetting
factors justify preplacement of the jacket despite this difficulty,
then counteracting magnetic repulsion supplied by the tractive
electromagnets or an external electromagnet may of assistance. The
coordinated use of two or more moving magnetic fields must
anticipate abrupt sidewise deflections.
[1811] To avoid abrupt shifts of the muzzle-head, which contains
magnetically susceptible matter such as the ferromagnetic cores of
the turret-motor and recovery electromagnet, as it moves among the
magnetic fields of an extrinsically magnetized stent-jacket with
stronger spaced apart bar magnets mounted about the outer surface
of the base-tube, the stent-jacket is usually placed after the
miniballs. The effect of stronger separate bar magnets mounted
about the outer surface of the base-tube on the muzzle-head can to
some extent be moderated by varying the polarity and intensity of
the fields generated by the miniball recovery tractive
electromagnets, (trap-extractor) magnets.
[1812] When the stent-jacket is placed prior to discharge
implantation, access to the ductus from the outside will have been
established, allowing the use of the recovery electromagnet in a
stay insertion tool to steer the muzzle-head when it would be drawn
aside by another less powerful magnetic field. Rotating an
eccentric stent-jacket about an artery to steer a muzzle-head or
another catheteric device is difficult, injures the adventitial
innervation and vascularization, and when an external electromagnet
can be used to obtain the same control noninvasively, is
unnecessary. Where this factor is contextually less significant, as
in implanting the trachea of a small dog with a collapsed dorsal
ligament, care must still be given to avoid the recurrent laryngeal
nerve.
[1813] So long as the effect of compression with any offsetting or
countering attractive forces can be duplicated and evaluated before
discharge by in situ testing described below in the section
entitled Testing and Tests and is not so forceful as precludes
implantation, the nonuniformity in exit velocity to achieve
penetration is treated no differently than are differences in
impact force required by pathology. Implantation is keyed to
preserving patency, which normally requires retraction of the
obstructive lesion. Generally, stenting miniballs that include
medication and/or radiation are infixed within the lesion, while
those used purely to retract are infixed alongside or opposite the
lesion.
[1814] If muzzle-head deflection is significant and a monobarrel
radial discharge muzzle-head that resists rotation by the
turret-motor or a multiple radial discharge barrel-assembly is to
implant medication miniballs, for example, in another arc, then a
midprocedurally lubricated muzzle-head of larger diameter or a
stent-jacket with opposing magnetization is used. A muzzle-head
with ferrous material omitted could be made, for example, by
transfer-molding and machining polytetrafluoroethylene. Omitting
recovery electromagnets and a turret-motor, such a muzzle-head
would avert not only the unfavorable but also the favorable effects
of magnetic attraction and do so with a critical loss in
controllability.
[1815] A combination-form barrel-assembly with an empty through and
through central channel using such a muzzle-head would allow the
insertion of a service catheter with iron head (distal end) as
needed to allow the use of an external electromagnet to assist in
steering the muzzle-head through tighter curves or to bring the
muzzle-head into contact or closer contact with the tissue to be
treated. However, even though such a device could be torqued to the
rotator angle needed and alternative measures described herein
would still allow the arrest and recovery of a dropped miniball,
the loss of recovery electromagnet and turret-motor function is
insupportable. The steering and abutting use of an external
electromagnet is no less applicable to a fully appointed
muzzle-head, but is unusable with any kind of muzzle-head when the
tractive force required would result in the dislodgement or
extraction of miniballs.
[1816] I4. Internal Environment-Resistant Base-Tube Polymers,
Metals, and Combinations Thereof
[1817] The primary object in base-tube and nonabsorbable
stent-jacket matrix structure is to achieve the required compliance
with smooth muscle action over a long service life. For a
stent-jacket to encircle a ductus embedded or invested within
tissue rather than situated within a body cavity, structural
breakdown with the formation of tiny cracks that progressively
reduce the elasticity and resilience of an implanted polymer is
accelerated. When chemical isolation and magnetization are imparted
by encapsulation within a nonreactive outer coating, any material
or combination of materials that afford the requisite elasticity
and resilience are also suitable.
[1818] Base-tube, part number 5 in FIGS. 2 thru 7, may comprise
intrinsically magnetizable rounded polymeric or metal sheet stock,
or nonmagnetizable rounded polymeric sheet stock to which small
permanent, usually neodymium magnets encapsulated to assure
chemical isolation of the toxic neodymium shown as part number 4 in
FIGS. 2 thru 7, or small electromagnets are fastened about the
outer surface. Magnetization is perpendicular to the longitudinal
axis of the substrate conduit or ductus, meaning the conduit or
ductus the jacket is positioned to encircle.
[1819] Base-tubes are perforated entirely through the outer shell
and closed cell viscoelastic polyurethane foam part number 5a in
FIGS. 2 thru 7 lining down to the outer surface of the substate
ductus with holes, or fenestrae, sufficiently large to assure shape
compliance, or shape accommodation, with the vasa vasora and
nervora that would otherwise be compressed and obstructed from the
environment, and to assure gas exchange between the substrate
adventitia and the surrounding internal environment, communication
thus essential to avoid the prompt inducement of atherosclerotic
degeneration (see, for example, De Meyer, G. R. Y., Van Put, D. J.,
Kockx, M. M., Van Schil, P., Bosmans, R., Bult, H., Buyssens, N.,
Vanmaele, R., and Herman, A. G. 1997. "Possible Mechanisms of
Collar-induced Intimal Thickening," Arteriosclerosis, Thrombosis,
and Vascular Biology 17(10):1924-1930). The fenestrae can be any
shape but should be as large as possible.
[1820] With any material, as the base-tube is made thicker,
flexibility is reduced along and by extension outward from the
longitudinal line opposite the side-slit or side-slot. Suitable
encapsulation materials must also therefore not only exhibit
resistance to phagocytic, hydrolytic and enzymatic breakdown but
afford flexibility consistent with compliance to the smooth muscle
action in the substrate ductus and do so in a thickness that will
withstand frequent flexion without fatigue for a period of years,
and preferably, to the end of life. A nonencapsulated stent-jacket
base-tube with encapsulated bar magnets mounted about its outer
surface and a nonencapsulated nonabsorbable matrix of a
quasi-intrinsically magnetized stent-jacket must be made of
implantable tubing that withstands the intracorporeal
environment.
[1821] Whereas an intrinsically magnetized stent-jacket of thin
ferromagnetic stainless spring steel is likely to last throughout
life, a loss in polymeric base-tube resilience due to the
development of microfractures and chemical breakdown in the
internal environment will disable an extraluminal stent of the
spaced apart magnet or quasi-instrincally magnetized types
described above in the section entitled Types of stent-jacket. The
moisture barrier-coated viscoelastic polyurethane foam lining of
stent- or shield-jacket also has a life of many years inside the
body. Moreover, this degradation will be accelerated in proportion
to the size and number of perforations provided to allow gas and
other chemical exchange at the outer surface of the ductus.
[1822] In considering uncoated or bare base-tube materials, inert
silicone elastomers such as those of polydimethylsiloxane sold by
Dow Corning under the trade name Silastic and Bluestar Silicones
under the trade name Silbione have a long record of extended life
without significant foreign body reaction when implanted (see, for
example, Sincoff, E. H., Liu, J. K., Matsen, L., Dogan, A., Kim,
I., McMenomey, S. O., and Delashaw, J. B. Jr. 2007. "A Novel
Treatment Approach to Cholesterol Granulomas. Technical Note,"
Journal of Neurosurgery 107(2):446-450; Machler, H. E., Schmidt, C.
H., Neuner, P., Iberer, F., Anelli-Monti, M., Dacar, D., Rigler,
B., and Kraft-Kinz, J. 1993. Twenty-four Years' Implant Duration of
the Aortic Starr-Edwards Silastic Ball Prosthesis: A Valve of the
Past?," European Journal of Cardiothoracic Surgery 7(3):114-116).
Means for discouraging the formation of foreign body giant cells on
materials containing polyurethane are addressed below in the
section entitled Materials Suitable for Rebound-directing
Double-wedge Linings.
[1823] The reputation of silicone is due at least in part to
leakage from breast implants and the injection of nonmedical grade
material for cosmetological purposes, often by incompetent
practitioners (see, for example, Schwartzfarb, E. M., Hametti, J.
M., Romanelli, P., and Ricotti, C. 2008. "Foreign Body Granuloma
Formation Secondary to Silicone Injection," Dermatology Online
Journal 14(7):20; Narins, R. S. and Beer, K. 2006. "Liquid
Injectable Silicone: A Review of Its History, Immunology, Technical
Considerations, Complications, and Potential," Plastic and
Reconstructive Surgery 118(3 Supplement):77S-84S). However, the
attribution of adverse results to impurity and/or incompetency of
liquid silicone has been cited as exaggerated (Chasan, P. E. 2007.
The History of Injectable Silicone Fluids for Soft-tissue
Augmentation," Plastic and Reconstructive Surgery
120(7):2034-2043).
[1824] Other more recent materials are significantly increasing
potential longevity within the internal environment (see, for
example Pinchuk, L. 1998. "Biostable Elastomeric Polymers Having
Quaternary Carbons," U.S. Pat. No. 5,741,331). Materials found
lacking under the more stringent requirements imposed on a
prosthetic tricuspid valve, for example, are still likely to prove
adequate in a base-tube, which outside the bloodstream, is not
constantly washed over by blood or subject to calcification, for
example (see, for example, Wang, Q., McGoron, A. J., Bianco, R.,
Kato, Y., Pinchuk, L., and Schoephoerster, R. T. 2010. "In-vivo
Assessment of a Novel Polymer (SIBS) Trileaflet Heart Valve,"
Journal of Heart Valve Disease 19(4):499-505) or load-bearing, for
example (see Pinchuk, L., Wilson, G. J., Barry, J. J.,
Schoephoerster, R. T., Parel, J. M., and Kennedy, J. P. 2008.
"Medical Applications of
Poly(styrene-block-isobutylene-block-styrene) ("SIBS"),"
Biomaterials 29(4):448-460).
[1825] Tubing that is able to withstand the salinity of the
intracorporeal environment can be extruded from pellets or diced
Bionate.RTM. polycarbonate-urethane copolymer (see, for example,
Ward, R. S. 2000. "Thermoplastic Silicone-Urethane Copolymers: A
New Class of Biomedical Elastomers," Medical Device and Diagnostic
Industry 22(4):68-77), produced by the Polymer Technology Group,
Inc., Berkeley, Calif., previously sold under the tradename
Corethane.RTM. Polycarbonate by Corvita, Inc. Other prospective
base-tube polymers from the same company include Biospan.RTM.
segmented polyurethane, Elasthane.RTM. thermoplastic
polyetherurethane, PurSil.RTM., silicone polyether urethane, and
Carbosil.RTM. silicone polycarbonate urethane, and from Thoratec,
Inc., Pleasanton, Calif., Thoralon.RTM. segmented
polyetherurethaneurea blended with a siloxane that includes a
surface-modifying additive. One such material exhibits a durometer
D-scale per ASTM D2240-02 test, Shore A reading at 15 seconds of 55
(see also Muller-Glauser, W., Lehmann, K. H., Bittmann, P., Bay,
U., Dittes, P., von Segesser, L., and Turina, M. 1988. "A Compliant
Small-diameter Vascular Prosthesis Lined with Functional Venous
Endothelial Cells," American Society for Artificial Internal Organs
Transactions 34(3):528-531).
[1826] Implanted AorTech International, Wahroonga, New South Wales,
Australia subsidiary AorTech Medical Devices, Rogers, Minnesota
Elast-Eon.TM. 2 80A, synthesized using poly(hexamethylene oxide)
(PHMO) and poly(dimethylsiloxane) (PDMS) macrodiols, has been
demonstrated to stand up well and with tolerable alteration in
mechanical properties over time (Simmons, A., Hyvarinen, J., Odell,
R. A., Martin, D. J., Gunatillake, P. A., Noble, K. R., and
Poole-Warren, L. A. 2004. "Long-term in Vivo Biostability of
Poly(dimethylsiloxane)/Poly(hexamethylene Oxide) Mixed
Macrodiol-based Polyurethane Elastomers," Biomaterials
25(20):4887-4900; Martin, D. J., Warren, L. A., Gunatillake, P. A.,
McCarthy, S. J., Meijs, G. F., and Schindhelm, K. 2000. "
Polydimethylsiloxane/Polyether-mixed Macrodiol-based Polyurethane
Elastomers: Biostability," Biomaterials 21(10): 1021-1029).
[1827] Macrodiol-based polyurethane elastomers also withstand
sterilization well, whether using gas plasma, steam, vapour phase
liquid chemical, or even multiple cycles using ethylene oxide or
gamma-irradiation (Simmons, A., Hyvarinen, J., and Poole-Warren, L.
2006. "The Effect of Sterilisation [sic] on a
Poly(dimethylsiloxane)/Poly(hexamethylene oxide) Mixed
Macrodiol-based Polyurethane Elastomer," Biomaterials
27(25):4484-4497.
[1828] The exposure of the base-tube or the matrix of a
quasi-intrinsically magnetized stent-jacket placed about an artery
within a sheath coursing through skeletal muscle, for example, is
less than that of a polymer exposed to digestive or catabolic
enzymes, for example. For this reason, the extraluminal component
of the stent described herein is able to supplant endoluminal
stents regardless of situation. However, the inner diameter of the
base-tube or extraluminal component exceeds that of the outer
diameter of the ductus by the thickness of the moisture
barrier-coated viscoelastic polyurethane foam lining, and to allow
the extraluminal component to encircle and expand and contract with
the substrate artery, it is longitudinally slit along one side.
[1829] Since placed within a sheath, the outer corners of the bar
magnets in an extrinsically magnetized stent-jacket of the discrete
or spaced apart magnet type would pulsate against the enveloping or
apposing tissue, for situation thus, a quasi-intrinsically
magnetized stent-jacket is used instead. When protrusion by
discrete magnets into the surrounding tissue is less prominent,
abrasive or probing injury is avoided because the outer corners of
the magnets are rounded and the magnets encapsulated together with
the base-tube in a rubbery polymer of plastisol-like softness for
bioinertness, hence longer life, and to prevent separation. An
extraluminal stent in an extremity can be used not only to stent
but to attract drug carrier nanoparticles from the passing blood
into the wall of the artery, something an endoluminal stent
cannot.
[1830] When the magnetic strength required of a stent-jacket or an
impasse-jacket used for drug targeting in an extremity is greater
than the space within the sheath would allow, the stent-jacket is
worn externally. A cuff of this kind is a magnet-wrap used as an
impasse-jacket and can be also be used as a kind of stent, such as
temporarily to palliate tracheomalacia in an infant or collapsed
trachea in a veterinary patient. The base-tubes of discrete magnet
type and the matrixes of quasi-intrinsically magnetized
stent-jackets can be extruded of individual or coextruded of
different materials laminated or blended to obtain any functional
restorative force.
[1831] I5. Protective Encapsulation of the Stent-Jacket
[1832] In an extrinsically magnetized stent-jacket, the magnets are
bonded or fastened to the base-tube and the two encapsulated
together as a unit before the moisture barrier-coated viscoelastic
polyurethane foam lining is bonded inside. This adds an additional
layer of protection against a release of toxic lanthanoid, thermal
insulation, and reinforces the magnet-base-tube bond to prevent
disconnection due to deterioration over time, a direct blow, or
exposure to extremes of temperature. Tantalum contrast is applied
to this outer coating.
[1833] This outer coating or casing can consist of
biaxially-oriented polyethylene terephthalate (boPET) is applied
(see, for example, Drobota, M., Aflori, M. and Barboiu, V. 2010.
"Protein Immobilization on Poly(Ethylene Terephthalate) Films
Modified by Plasma and Chemical Treatments," Digest Journal of
Nanomaterials and Biostructures 5(1): 35-42), such as by
heat-shrinking and heat sealing, the temperature thereof not high
enough to affect the elasticity of the base-tube or magnetization
of the bar magnets. Further jacketing within polyethylene to
enhance puncture resistance is usually nonessential. Intrinsically
and quasi-intrinsically magnetized stent-jackets seldom require
encapsulation.
[1834] I6. Stent-Jackets with Sling String Pull Opener
[1835] The hook ends of stent-jacket insertion tools pivot to allow
use at awkward angles. When the location makes retraction of the
side-slit or side-slot and encirclement of the ductus difficult
despite this, pull-strings can be attached. The pull-strings of
higher tensile strength absorbable (such as
glycolide-dioxanone-trimethylene carbonate) or nonabsorbable
braided suture include strands or monofilaments that diverge or fan
out hammock-style to attach to a strip of tape with a strong
pressure sensitive backing. Prior to insertion, one strip of tape
is attached parallel to and at a slight interval from each side of
the slit or slot or side-slot. The pull-strings and a stent-jacket
insertion tool are seldom used at the same time.
[1836] Both strings are pulled by one hand to open the stent-jacket
and the tip of a probe, pliars, or hemostat, for example, used to
press against the stent-jacket opposite the slit around the ductus.
If awkward adjustments in angle make it necessary, surgical pliars
are used to pull at one or more of the strands. Once the
stent-jacket has been placed, the suture if nonabsorbable can be
snipped away or if absorbable can be more thoroughly disintegrated
if swabbed with hydrogen peroxide just prior withdrawal and
closure. Absorbable materials are always subject to premature
dissolution under conditions of fever, infection, or an
accumulation of aqueous fluid as in edema or ascites.
[1837] I7. Stent and Shield-Jacket Protective Linings
[1838] I7a. Double-Wedge Stent- and Shield-Jacket Rebound-Directing
Linings
[1839] I7a(1). Conformation of Double-Wedge Linings
[1840] Miniballs used in arteries are so small that a perforation
quickly seals even with the platelet blocker administered. Those
used in the gut are larger but proportionally so small that
perforation does not result in leakage necessitating reentry.
Prepositioned perforation shielding jackets are provided as an
extra precaution in instances where perforation would pose a
greater risk. Double-wedge stent-jacket linings have an inclined
interface between an outer resilient or rubbery and a complementary
inner moisture barrier-coated viscoelastic polyurethane foam layer.
Alternatively, as shown in FIG. 12, when the base-tube is itself of
suitable resilience and increases in thickness from one end to the
other, then no resilient wedge-shaped layer between the base-tube
and the complementary wedge-shaped moisture barrier-coated
viscoelastic polyurethane foam lining may be necessary, the latter
referred to as a wedged lining
[1841] Thus, the outer wedge can be the base-tube of an
extrinsically or matrix of a quasi-intrinsically magnetized
stent-jacket or it can be an additional wedge of a rubbery polymer
interposed between the base-tube and the foam inner lining.
Although varying the thickness, material, and the use of
coextrusions allow jacket elasticity for compliance to the
expansion and contraction of the substrate (treated, encircled)
ductus to be adjusted, a double-wedge insert lining segregates the
properties that contribute to this physiological compliance from
those that give the internal surface a resilience suitable for
redirecting rebounds. The wedged layers can be directly molded or
made from flat sheet stock razor shaved to the angle of inclination
specified, then thermoformed into a tube with side-slit or slot as
needed representing the gap between the sides as short of
flush.
[1842] Any additional ingredients for cross-linking must be
suitable for implantation. While the overall thickness of a lining
intended to assist in the control of rebounds is unaffected, the
density of the moisture barrier-coated viscoelastic polyurethane
foam and more resilient outer wedge or internal surface of the
base-tube must meet the primary desiderata of reducing the momentum
of and redirecting or steering rebounds, which calls for certain
relations between the material and surface geometry of both lining
materials, and this is accomplished by means of a layer that
consists of two sublayers at complementary angles as described. A
segmented sectional stent-jacket, or one made from a continuous
length of flexible tubing such as that shown in FIG. 13, is not of
the latter type, which necessitates costly machining to manufacture
but composed of individual unit or modular jackets wherein each has
inserted within it a double-wedge of which the outer is not
identical with the continuous tube.
[1843] Stent-jacket linings are devised to incorporate
anti-migration, tissue infiltration or integration encouraging, and
perforation preventing features in one and the same lining, a
disproportionate requirement for one of these as opposed to the
others arising infrequently. Moisture barrier-coated viscoelastic
polyurethane foam, especially when treated to encourage
infiltration serves these purposes. As addressed above in the
section entitled Sequence of Stent-jacket Placement and
Implantation, when the stent-jacket is placed prior to initiating
discharge, a resilient lining of suitable conformation can avert
the rebound of a perforating miniball into the lumen. Depending
upon the force of impact (momentum) and resilience of the lining, a
parallel or noninclined foam lining will trap a less forceful
miniball but if backed by a rubbery base-tube, can rebound a more
forceful one distally and medially, into the lumen.
[1844] A double-wedge can trap the one and redirect the rebound to
implant the ductus wall shortly distal to the point intended but
still functional for medicating or stenting the wall, for example.
In the vascular tree, protection from the risk of embolization
obtained by prepositioning a stent-jacket with a double-wedge
lining can be reinforced by the additional preplacement downstream
of an impasse-jacket, as addressed in the section above entitled
Concept of the Impasse-jacket and below in the section entitled
Miniball and Ferrofluid-borne Particle-impassable Jackets, or
Impasse-jackets.
[1845] The need for additional percutaneous access to place a
shield-jacket or impasse-jacket can be dispensed with when a
powerful extracorporeal electromagnet with probe strategically
aimed downstream to arrest a miniball loose in the bloodstream and
extract it to a point outside the ductus to a location where it
will be least risky to do so can be used, as addressed in section
X2c below entitled Stereotactic Arrest and Extraction of a
Circulating, Dangerously Mispositioned, or Embolizing Miniball. If
the lines of force are directional and the probe distant from the
intended implantation site, this has the added benefit of not
risking dislodgement of nearby implants.
[1846] I7a(2). Functional Background to Double-Wedge Linings
[1847] A double-wedge lined radiation shield-jacket protects
against perforation into the tissue surrounding the ductus of
radiation seed-miniballs, although such use only expedites recovery
if accidentally rebounding into the lumen; a trap impasse-jacket or
jackets and prepositioned external electromagnet make such use
additionally precautionary. While an impasse-jacket used strictly
as a downstream trap is generally absorbable, one positioned over a
lesioned segment to serve both immediately as a trap and to attract
drug carrier nanoparticles into the vessel wall at any later date
is nonabsorbable. An impasse-jacket originally placed for the
purpose of drug targeting will generally negate the need to place
an impasse-jacket as a protective trap in support of a later
procedure.
[1848] This dual functionality is imparted by the facts that
miniballs will always be of a diameter proportional to that of the
vessel, and both trapping and drug targeting necessitate a strength
of magnetization greater than that appropriate in most
stent-jackets. By comparison, stent-jackets are intended to impose
no greater tractive force than is needed to maintain patency
without delamination or pull-through and are not conformed to allow
immediate extraction of a trapped miniball with the aid of an
extracorporeal electromagnet. The invasive factor of creating two
or three entry incisions, one to insert the barrel-assembly, the
second to insert the stent-jacket, and third to insert the
impasse-jacket, is weighed against the small size of these implants
and the paths required to gain access to the treatment site.
[1849] Application with an open surgical field makes placing
stopping and stent-jackets a minor task. A double-wedge
shield-jacket for placement about the segment to be implanted
before initiating discharge to contain any perforations consists of
a base-tube with double-wedge lining without magnetization whether
with extrinsic discrete tiny bar magnets about the outer surface of
the base-tube or by lamination with an outer quasi-intrinsically
magnetized layer. It is suited to protecting against perforations,
but unlike a shield-jacket with a thinner lining, less efficient at
warming the substrate segment through heat induction when desired.
The need for a shield-jacket purely to protect against perforations
is seldom necessary; due to the small size of most miniballs,
perforations pose little if any risk of significant much less
serious injury.
[1850] Exceptional situations such as the possibility of striking a
recurrent laryngeal nerve, for example, make provision of a shield
necessary. Unpredictable with diseased tissue, a propensity for
wall failure necessitates preliminary in situ testing as described
in the section below entitled In situ Test on Endoluminal Approach
for Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation. When an immediate source or sources of medication
and/or radiation within the ductus wall would be advantageous over
systemic or more dispersed treatment, miniballs that consist purely
of medication and/or emit radiation can be implanted. When
miniballs are chosen over placement of an impasse-jacket,
precautions should be taken to prevent the loss of a miniball
downstream and embolization.
[1851] This can take the form of an impasse-jacket prepositioned
downstream and/or a double-wedge lined shield-jacket As is the case
with prostatic brachytherapy, radiation spherules (seed miniballs,
miniball seeds) are allowed to remain permanently, the
thrombogenicity and invasiveness of a second procedure to remove
these (through use of the recovery electromagnets) unnecessary.
Medication miniballs are absorbed over time and any remainder of
seeds left within the wall, and not released downstream. If the
luminal wall is malacotic, then to implant medication miniballs
should be discounted in favor of medication stays, which require
only permural access, while ballistic implantation requires
transluminal and additional permural access to insert a
precautionary double-wedge shield and/or downstream trap
impasse-jacket.
[1852] The inner wedge moisture barrier-coated viscoelastic
polyurethane foam lining averts migration, and can be chosen and
further treated to encourage tissue ingrowth and adhesion and can
absorb and retain more of a perforation sealant and/or antibiotic,
for example. The more acute is the angle of discharge in relation
to the internal surface of the ductus, the weaker in magnitude is
the vector normal to the intima that causes the miniball to
penetrate the ductus wall and the greater the forward or down-lumen
vector. Too acute an angle of discharge risks failure to penetrate,
and a sclerotic condition, lesion, or mineral deposit of
hydroxyapatite (hydroxylapatite) or salt increases the possibility
for a glancing rebound. The angle of discharge is therefore limited
and determines the angle of inclination of the double-wedge lining
used with a given muzzle-head.
[1853] In increasing order of unwanted outcome with respect to an
artery, nonfunctional discharges are those that terminate too far
distad, perforate, or rebound into the lumen. Given the need to
minimize the jacket diameter in order to avoid encroaching upon
adjacent structures, the foam cannot simply be made so thick that
it would retain any rebound within a jacket of smaller diameter.
While consideration here is to an outer wedge of a resilience that
preserves momentum to support rebound with reentry into the ductus,
the conformation of elements described makes it no less possible to
choose a material for the foam backing resilient surface that is
absorbent thereby reducing the chance that a perforating miniball
will reenter the ductus at any point.
[1854] Accordingly, a means for redirecting forcible rebounds so
that the angle of rebound will not allow the miniball to penetrate
into the lumen is necessary. Correction of the rebound angle
necessitates an inclined resilient rebound surface outside the
moisture barrier-coated viscoelastic polyurethane foam lining of
complementary distolaterally increasing thickness base-tube. When a
double-wedge lined shield-jacket is used with the placement of
medicinal miniballs, only those with a trajectory terminus too
distal in relation to the lesion to be treated will be
nonfunctional. To impart an angle of rebound that will redirect the
miniball to a functional or stent-encircled location requires the
interposition of a resilient surface that distolaterally inclined,
shifts the rebound abluminally.
[1855] When stenting miniballs are placed, the first object in the
use of a double-wedge lined shield-jacket or stent-jacket is to
prevent a miniball from rebounding into the lumen, and the second
to redirect the miniball to a ductus-intramural location that
although distal relative to the location intended, is still
functional in falling within the stent-jacket. Reducing the
acuteness of discharge thus reduces the tendency toward such
nonfunctional discharges. The use of a double-wedge lining offsets
a more stringent limitation on acuteness by imparting an angle of
rebound that is sufficiently more acute than that of discharge to
redirect the miniball to a point distal but still
ductus-intramural; these considerations demand that the angle of
discharge and the inclination of the lining be coordinated to
result in a redirection of the miniball that is still
functional.
[1856] Provided the lumen wall is not at the same time compressed
as to be made too thin to implant, using an external electromagnet
to draw the exit-hole flush against the endothelium may allow the
angle of discharge to be made more acute; however, the magnetic
field should be highly directional and care given not to extract
implanted miniballs. Resistance to compression is usually present
because the wall is sclerosed or contains a firm lesion.
Energization of the facing recovery electromagnet during discharge
can be used to slightly bend the trajectory, but the use of a high
amplitude similarly risks the dislodging or extracting of nearby
implants. An advantage in the arrest of a miniball downstream is
distance from neighboring implants.
[1857] A powerful external electromagnet, as addressed in the
preceding section entitled Conformation of Double-wedge Linings,
can both arrest and extract a miniball from the lumen, while an
impasse-jacket will trap and retain a miniball, which if necessary,
can be extracted with the aid of a powerful external electromagnet.
Stent-jackets and shield-jackets with or without a double-wedge
lining do not allow extraction thus. When a high exit velocity
and/or loss in intrinsic elasticity of the ductus wall due to
disease increase the chance for a perforation or rebound into the
lumen, the shield-jacket or stent-jacket is placed prior to
initiating discharge. The use of a double-wedge lining is based
upon the results of in situ testing, addressed below in the section
entitled Testing and Tests, and complications to which the the
conditions present predispose.
[1858] With increasing momentum and suddenness of impact, wall
resilience less predisposes to rebound but the chance of
perforation is increased. Placing a jacket without a cushion lining
about the ductus provides a rebound surface to prevent perforations
but which must be angled to avoid the most unwanted consequence,
which is a rebound into the lumen. The moisture barrier-coated
viscoelastic polyurethane foam lining slows and can trap a miniball
preventing rebound. Absent pathology that hardens the wall, such as
a neoplasm or firm plaque, the wall will be compressible, so that a
firm backing does not contribute to penetrability as would allow
the exit velocity to be reduced; unless a miniball impacts with
perforative force, the preplacement of the stent-jacket will make
little difference. Moisture barrier-coated viscoelastic
polyurethane foam linings are addressed below in the section
entitled Stent and Shield-jacket Moisture barrier-coated
viscoelastic polyurethane foam Linings.
[1859] The density, shock impact response, and thickness of the
laminae of the wall and foam all contribute to the result, and
since the tissue of the ductus may vary from one point to the next
and the thickness of the foam must continuously change according to
the angle of inclination dictated by the angle of discharge,
complete control over the result of discharge can never be
achieved. The additional layers of the shield or stent-jacket
encircling the ductus can be produced to a high standard of
consistency. However, the variability of the tissue and the fact
that the double-wedge must be inclined for the angle of discharge
so that it varies in thickness at every point along its length,
means that slightly different conditions pertain depending upon the
exact point of impact.
[1860] Every element subject to multiple variables, the complexity
of the overall physical system, because it includes tissue
consisting of laminae having different properties further altered
by disease, precludes attaining certainty of outcome, but not
predictability sufficient to allow effective treatment. Backed by a
compliant foam lining, the residual momentum of the miniball, the
strength and elasticity of the adventitia, and the density, shock
impact response, and thickness of the foam lining, along the
trajectory determine the result of discharge. The thickness of the
inclined foam different for every point and angle of entry along
the length of the jacket, these factors determine whether the
miniball is:
[1861] 1. Stopped without perforating the adventitia to remain
subadventitial as desired.
[1862] 2. Forcibly drives the adventitia through the foam lining to
rebound off the resilient surface behind the foam lining without
perforating but imparting negligible stretching injury to the
adventitia.
[1863] 3. Perforates the adventitia to become trapped in the lining
with little rebound.
[1864] 4. Does so but delivers a blow to the adventitia; or
[1865] 5. Continues after rebound with sufficient residual momentum
to perforate and reenter the ductus.
[1866] The angle, residual momentum, and penetrability of each
layer of the ductus now determine whether the miniball is trapped
within the ductus wall or reperforates into the lumen. If due to an
irregularity such as a mineral deposit, the angle of rebound is
deviated from equally and oppositely acute to obtuse, then entry
into the lumen may result. If the residual momentum is high enough,
such irregularities may be forced aside or perforated by the
miniball. However, if the momentum has been dissipated and the
irregularity larger, deflection will result. While the
barrel-assembly is equipped with recovery electromagnets and a
run-ahead trap-filter that would recover the miniball, and
additional measures to include the prepositioning downstream of an
impasse-jacket and/or extracorporeal electromagnet will be
described, it is preferable to minimize if not eliminate
nonfunctional discharges.
[1867] Thus, at every point along the trajectory, the angle of
travel and the mechanical properties and the strength and thickness
of each material encountered determine the exact path the
trajectory will describe. The inclined and therefore continuously
varying angle and thickness of the foam lining and its resilient
backing of complementary or reciprocal inclination are based upon
the angle of discharge to slow and steer the miniball away from the
lumen. The thinner the foam at the point of impact, the less is the
momentum depleted and the higher the likelihood for overextended
travel. Consequently, a given muzzle-head must be used with
double-wedge jackets devised for its angle of discharge. The angle
of discharge for each exit-hole in a multiple barrel radial
discharge barrel-assembly is the same.
[1868] However, provided the testing procedure reveals the
conditions to confront and the probable result of discharge, the
odds that significant deviations will go undetected will be less as
the number of points tested is increased. Moreover, in situ testing
precedes and can therefore determine the choice of a muzzle-head of
a certain discharge angle, hence, the inclination of the
double-wedge lining. Furthermore, the foam along the length of the
shield or jacket can be varied to offset differences in thickness.
Histological variability is usually not immutable, in situ testing
also indicating the suitability of preparatory treatment with a
sclerosant, tumefacient, or sealant, for example, which an ablation
or angioplasty-capable barrel-assembly or a radial projection
catheter can release into the lumen, swab onto the intima, or
locally inject alone or in any combination.
[1869] In situ testing to establish the proper discharge
exit-velocty that includes numerous testing points along the lumen
wall will usually reveal any weak spots. Testing allows the
discharge exit-velocty to be correctly set, so that perforations
should seldom if ever occur. Provided a weak spot is missed and the
trajectory passes through it, then a perforation will occur.
Ordinarily, the small size and composition of a miniball means that
a perforation will be innocuous, at worst nicking a nerve or
ganglion or severing a nervelet resulting in temporary partial or
localized dysfunction, or a larger vessel that because the puncture
is small, promptly seals even with anticoagulant and/or
antiplatelet blockade having been administered, or a small vessel,
resulting in localized hemorrhage at a level where collateral
circulation abundant. Nevertheless, certain circumstances
necessitate means for preventing a perforation.
[1870] For example, high concentration dose medicinal or
radiation-emitting miniballs, that perforate must be prevented from
coming to rest in tissue where the medication or radiation would
have the potential to do harm. Perforation can be prevented through
the temporary placement of a shield-jacket or by prepositioning the
stent-jacket. The problem then becomes preventing rebound into the
lumen or infixion at a location too far distad to fall within the
stent-jacket or to achieve the proximity required for effective
uptake by the targeted lesion or segment of the medication or
radiation; placing a shield prior to discharge prevents must not
simply take the momentum that would have perforated to produce an
outcome that is worse. The muzzle-head is configured to discharge
at an acute angle, which is less amenable to perforation than
would, to cite the extreme, discharge normal to the lumen wall.
[1871] The more acute is the angle of discharge, the less likely is
a perforation, but a trajectory containing a uncharacteristically
disproportionate amount of soft tissue can allow a perforation even
though the exit velocity is properly set for the tissue as a whole.
In general, provided the exit-velocity is high enough to overcome
differences of tissue hardness along the trajectory, the angle of
rebound off a hypothetical flat plate positioned parallel to the
lumen would be substantially equal and opposite to the angle of
impact. Even though rebound is equally and oppositely acute, if the
momentum of the rebound is high enough and impedance by the media
and internal elastic lamina inadequate, the miniball, could
penetrate into the lumen. Angling the plate distolaterally shifts
the angle of impact so that the equal but opposite rebound is
likewise displaced distolaterally, hence shifted away from the
lumen.
[1872] The internal surface of the actual shield not flat but
circular, rebound is in two dimensions, but the vertical dimension
will seldom if ever be that problematic. If rebound causes the
miniball to continue into the ductus, a small concretion is
unlikely to redirect a miniball with increased distal direction and
sufficient momentum into the lumen. The distomedial reorientation
of the rebound recovery leg is likely to bring the miniball to a
terminus distal to that desired but within the wall. If this brings
a medicinal miniball to distal to the target lesion, for example,
or a stenting miniball to a point beyond the distal margin of the
stent-jacket, then placement is nonfunctional. Thus, the odds of a
problematic terminus are reduced and the operator afforded the
opportuinty to reduce the exit velocity with little harm before
resuming discharge.
[1873] The next miniball may still not seat at a functional point;
however, entry into the lumen should not result. By incorporating
an inclined surface of suitable resilience to redirect the miniball
with reduced momentum so that upon rebounding, the miniball will
seat medially or subadventitially (perimedially), the risk of entry
into the lumen should be all but eliminated. In a stent-jacket with
double-wedge, the moisture barrier-coated viscoelastic polyurethane
foam component of the inner or adluminal of the double-wedge
protects the microstructures about the ductus, negating the
compression on these that the magnetic field would otherwise
impose. At its thinnest point proximally, the foam wedge must
therefore be thick enough to accommodate the fine vessels and
nerves of the adventitia or fibrosa.
[1874] Neither should the inner foam layer be so thick or resilient
at the distal end that it prevents the miniball-displaced
adventitia from contact with the inclined surface of the
wedge-insert to provide rebound redirection without perforation of
the adventitia. If the foam-wedge is too thick, the miniball is
more likely to perforate the adventitia and come to rest in the
foam where it would be harmless but nonfunctional. It is preferable
to conserve the functionality resulting from each discharge as well
as minimize the risk of perforation. The availability of materials
that cover a wide range of resilience makes the thickness required
of the outer or abluminal deflection bumper or bounce-wedge less
stringent.
[1875] The angles of impact and inclination of the planar surface
junction between the complementary wedges determine the angle of
miniball rebound, while the firmness and shock response of both
layers determine the effect on miniball momentum. If driving the
adventitia into the outer bounce-wedge with a force of impact that
is subperforating, the miniball does not enter the foam-wedge but
is rebounded at an acute forward angle without escaping from within
the wall of the ductus. The interposition of tissue, much less
tissue that has been altered by disease, represents a given element
of uncertainty that necessitates in situ testing, addressed below
in the section entitle Testing and Tests.
[1876] A tendency of the ductus wall to delaminate, as addressed
below in the section entitled In Situ Test upon Endoluminal
Approach for Intra- or Inter-laminar Separation (Delamination)
should be gauged as should its susceptibility based upon hardness
as addressed below in the section entitled In Situ Testpon
Endoluminal Approach for Susceptibility of the Ductus Wall to
Puncture, Penetration, and Perforation. Provided a medicinal
miniball that reenters the ductus wall does not stop too far beyond
the lesion, it will still be functional. Similarly, so long as it
does not pass the distal end of the stent-jacket, a stenting
miniball will remain functional.
[1877] If partially perforating the adventitia without passing
through it, then the miniball may eventually be pulled into the
foam-wedge by the attraction of the magnets; if perforating, then
the miniball is trapped within the foam and the adventitia returns
to its predischarge average position with a tiny puncture wound
that should soon heal and close. Both eventualities represent
nonfunctional results. The foam-wedge can be wetted and infiltrated
with an antibiotic, anti-inflammatory, antithrombogenic, or any
other medication in liquid form. The use of an antibiotic thus in a
spine and rib type stent-jacket for the gut, for example, militates
against infection consequent to a minor spilling of contents.
[1878] Trapped within the foam, the miniball does not protrude into
or rub against the adventitia as it would were the internal surface
of the base-tube applied directly to the adventita. In manufacture,
straight-line, that is, noninclined or nonwedged and double-wedge
insert linings of different angles are produced for shield-jackets
and stent-jackets of different internal diameter. Regardless of
type, the jacket together with any added layer or bar magnets
mounted to its outer surface is first encapsulated for chemical
isolation. The insert is then introduced and bonded with an
adhesive or by ultrasonic welding. The adhesive and use of heat to
bond the wedge insert to the internal surface of the base-tube
depends upon the materials, low viscosity Loctite.RTM. Indigo.TM.
3554.TM. usable for most.
[1879] Typically, the material of the rebound or bounce-wedge is
silicone rubber or a thermoplastic polyurethane polymer with a
durometer value, resilience, and shape selected for rebound and
razor die cut to the angle or rebound desired. The ductus is tested
before placing a shield-jacket or stent-jacket, and if perforated
in testing, then with stent-jackets having linings that differ in
resilience, the rebound imparted to the test rod translated into
equivalent rebound of the miniball proposed for use. To achieve
accurate discharge and minimize perforations, shield-jackets and
stent-jackets are specified for a certain range of test
results.
[1880] A ductus determined by testing, as will be described below,
to include malacotic areas (areas that have become softened,
weakened, by disease), which increase the chances for perforations,
is treated by injection of a tissue binder and mantled about with a
shield-jacket or stent-jacket before discharge. Such jackets are
usually of the double-wedge type. Other measures to assist in
achieving discharge accuracy apply regardless of the type jacket if
any. For example, to avoid the motion as well as the increase in
density, hence, effective hardness of the smooth muscle in the wall
of a ductus during peristaltic contraction (rigor, contracture,
stiffness) discharge is performed with the ductus quiescent, the
discharges synchronized to the passage of the contractive waves, or
when aperiodic as reduces the confidence of anticipation, with the
ductus anesthetized.
[1881] If necessary, peristalsis can be subdued or slowed down with
drugs such as loperamide, diphenoxylate, or arrested with
spasmolytics such as butylbromide (hyoscine
butylbromide/Buscopan.RTM.), hexamethonium, epinephrine, or
sufentanil, with reversal by means of a prokinetic (properistaltic)
such as metoclopramide (Paspertin.RTM.), cerulein, or neostigmine
(see, for example, Thaina, P., Poonpanang, P. and Sawangjaroen, K.
2005. "Comparison of Spasmolytic Activities of Piper Longum, P.
Sarmentosum and Quercus Infectoria Extracts with Loperamide and
Verapamil in Rat and Guinea Pig Intestinal Tissues," in Acta
Horticulturae 680: III, Secretariat of the International Union of
Biological Sciences, International Society for Horticultural
Science, World Conference on Medicinal and Aromatic Plants, Volume
6: Traditional Medicine and Nutraceuticals, 680:183-189 [available
at http://www.actahort.org/books/680/680_28.htm]. See also the
section below entitled Motional Stabilization of the Implant
Insertion Site.
[1882] In arteries, discharge is triggered on the diastoles, where
the resistance to penetration and perforation attributable to
changes in vasotonicity are reflected in the results of testing as
described in the section below entitled In situ Test on Endoluminal
Approach for Susceptibility of the Ductus Wall to Puncture,
Penetration, and Perforation. Means for dealing with an excessive
rate and/or an arrythmia are addressed below in the section
entitled Motional Stabilization of the Implant Insertion Site. When
the shield or stent-jacket is placed prior to initiating discharge,
there should be no effect on expansion with the pulse, and
compression of the foam lining should be slight. To limit expansion
on the systoles, a shield-, stent-, or other type jacket with a
non-double-wedge moisture barrier-coated viscoelastic polyurethane
foam lining and side-straps can be temporarily tightened during
discharge, even to overlap the edges of the side-slit, but only if
the lining is not compressed too thinly to trap a miniball that
perforates.
[1883] This is less often permissible with a double-wedge lining
where the thinner proximal end of foam wedge is usually compressed
too thin. Since only expansion is constrained, this is of little
value for stabilizing peristaltic action. The moisture
barrier-coated viscoelastic polyurethane foam can be coated or
suffused with such medication, as addressed below in the section
entitled Double-wedge Stent- and Shield-jacket Rebound-directing
Linings. When a miniball impacts against the adventitia with
sufficient force to compress the moisture barrier-coated
viscoelastic polyurethane foam flush against the internal surface
of the base-tube but not to perforate the adventitia, the shock
response, indentation force deflection, and recovery rate, or rate
sensitivity, of the foam absorb the shock, with additional
absorption of momentum or shock reduction provided by the resilient
surface relatively small.
[1884] This averts perforation through the adventitia, so that the
miniball remains contained within the wall of the ductus. As shown
in FIG. 10, a miniball that strikes the adventitia with sufficient
force to perforate it will compress the moisture barrier-coated
viscoelastic polyurethane foam lining, rebound off of the resilient
inclined surface behind, come to rest, and remain trapped within
the moisture barrier-coated viscoelastic polyurethane foam lining.
If the momentum of the miniball on rebounding adluminally is not
sufficient to perforate the intima, the miniball is retained within
the wall of the ductus, and depending upon the strength of the wall
layers, typically stopped perimedially (subadventitially) or in the
media. However, as shown in FIG. 11, when the striking-point along
the diseased ductus is atypical in having lost hardness or the
momentum of rebound is great enough, the miniball can continue
through the wall to perforate into the lumen.
[1885] Perforation with a foam-lined shield in position has less
potential for complications than does containment within the wall.
The miniball may drive the foam flush against the resilient
inclined surface, which sustains sufficient momentum to allow
perforation into the lumen. A conventional stent-jacket with only a
parallel foam lining would trap the miniball preventing it from
entering the lumen, but lack the ability to redirect a miniball to
a location that would preserve a portion of its function. Whereas
the extra-adventitial trapping of a miniball eliminates any risk it
could pose, it does so with an increase in jacket diameter and
fails to preserve the medicinal, radioactive, and/or magnetic
attractive functionality of the discharge.
[1886] Whether this or the relative security of entrapment within
the foam with little chance for a rebound into the lumen is a
clinical judgment. When the adventitia has the elasticity and
strength to thwart perforation so that the miniball forces the
striking-point and surrounding tissue through the foam against the
internal surface of the base-tube, a stent-jacket with a
distolaterally (distoabluminally) inclined lining as shown in FIG.
12 can often redirect the rebound to a location within the wall of
the ductus so that a medicinal miniball still comes to rest close
enough to the targeted area to medicate it or a stenting miniball
will still be enclosed by the stent-jacket.
[1887] I7a(3). Materials Suitable for Rebound-Directing
Double-Wedge Linings
[1888] Circumstances recommending the use of a shield-jacket or
preplacement of a stent-jacket with a double-wedge lining are
addressed above in the section of like title. Double-wedge lined
shield-jackets and stent-jackets for placement before initiating
discharge are intended primarily to reduce the incidence of
nonfunctional miniball placement and secondarily to prevent a
perforation in exceptional circumstances when vulnerable anatomy
might be struck. Jacket linings must exclude material that could
fragment and injure neighboring tissue or introduced into the lumen
by a rebound. The inner inclined layer or wedge is made of
viscoelastic polyurethane moisture barrier-coated viscoelastic
polyurethane foam, addressed above in the section entitled Necrosis
and atherogenesis-noninducing conformation of stent-jackets, having
properties suitable for the ductus.
[1889] This wedge may consist of a proximal-distal formation of
adjacent sections of moisture barrier-coated viscoelastic
polyurethane foam having miniball impact accommodation or shape
compliance that varies in proportion to the thickness of that
section. The adhesive used to bond the inner foam wedge to the
outer more resilient wedge should be soft enough when cured that a
miniball which strikes the outer layer without sufficient momentum
to rebound will be trapped at the interface, whether moving along
the interface before coming to a stop. The rebound characteristics
at all points of impact along the double-wedge should be uniform.
This will necessitate graduation in one or both the inner foam and
outer bounce wedge components from proximal to the distal end. For
both inner and outer wedges, polymers and copolymers that resist
degradation in resilience due to cracking within the internal
environment are required.
[1890] The outer or bounce-wedge can consist of silicone-urethane,
for example. Assembling the inner foam wedge of sections graduated
for rebound consistency will usually eliminate the need to
similarly assemble the outer bounce-wedge of sections. The outer
bounce-wedge or bumper should exhibit a firmer rubber-like hardness
on the order of 70 Shore durometer A scale at normal body
temperature (Yu, J-H., Dillard, D. A., and Lefebvre, D. R. 2001.
"Pressure and Shear Stress Distributions of an Elastomer
Constrained by a Cylinder of Finite Length," International Journal
of Solids and Structures 38(38-39):6839-6849). Double bond
polyurethane, available from Griffith Polymers Incorporated,
Tualatin, Oregon, can also be used, as can the material specified
in the section above entitled Internal Environment-resistant
Base-tube Polymers, Metals, and Combinations Thereof in the
appropriate hardness and resilience, which is more pertinent when
the outer wedge is integral with the base-tube as its inner
surface.
[1891] The inner layer should seldom if ever require any additional
anti-migration surface treatment as addressed below in the section
entitled Stent- and Shield-jacket Anti-migration Linings. Since the
double-wedge lining is placed prior to initiating discharge, it
must not contain any substance structural or coated thereon that
might do harm were it inoculated into the wall of the ductus when a
miniball rebounded to become embedded therein. To reduce the risk
of migration, the internal surface of the double-wedge base-tube
insert can be embossed or textured, but only to the extent that
such relief or depression exercises little if any effect upon
function and the direction of rebound.
[1892] The wedges are produced by dicing a sheet of the wedge
material having a thickness equal to the length of the wedges with
a razor-edged steel rule foam cutting die configured as a grid with
numerous rectangles each diagonally bisected to create the
complementary acute right triangular wedges in the cutting press.
The use of heat or laser cutting should not be necessary for
materials of appropriate density. The complementary halves must be
bonded with an adhesive that upon curing will not fragment if
subjected to relatively high density implantation by a multiple
barrel radial discharge barrel-assembly in automatic discharge
mode.
[1893] The complementary wedges can be bonded together and inserted
into a tube if not the actual base-tube or shield-jacket to cure,
although the extent of displacement at the interface when the wedge
halves are rolled following curing of the adhesive should usually
be too slight to require that the two be bonded only after having
been rolled into a tube shape. Suitable adhesives include
biocompatibly plasticized 2-octylcyanoacrylate, n-butyl, or a
longer chain cyanoacrylate cement. Biocompatible plasticizers
include acetyl tri-n-butyl citrate, acetyl trihexyl citrate, butyl
benzyl phthalate, dibutyl phthalate, dioctyl phthalate, n-butryl
tri-n-hexyl citrate, and diethylene glycol dibenzoate (Greff, R. J.
and Byram, M. M. 1998. "Cyanoacrylate Compositions Comprising an
Antimicrobial Agent," U.S. Pat. No. 5,783,177). The base-tube is
not opened flat to insert the double-wedge lining.
[1894] Instead, the double-wedge lining is bonded having been
inserted within the actual base-tube, or if a laminated jacket,
then within a tube of equivalent diameter. Alternatively, the
double-wedge lining is manually rolled around a mandrel that is
slightly larger in diameter than the internal diameter of the
equivalent base-tube and held in place with a tab of
pressure-sensitive tape. Whether made as such or for insertion when
needed by the operator, the outer surface of the double-wedge is
coated with adhesive, and the base-tube or if a laminated type
jacket, then a tube of equivalent diameter opened just enough to
insert the lining so that the ends of the lining and base-tube
align.
[1895] To inhibit the adhesion of macrophages and formation of
foreign body giant cells that would degrade any implant with an
outer surface of polyurethane (Labow, R. S., Sa, D., Matheson, L.
A., Dinnes, D. L., and Santerre, J. P. 2005. "The Human Macrophage
Response During Differentiation and Biodegradation on
Polycarbonate-based Polyurethanes: Dependence on Hard Segment
Chemistry," Biomaterials 26(35):7357-7166; Visai, L., Rindi, S.,
Speziale, P., Petrini, P., Fare, S., and Tanzi, M. C. 2002. "In
Vitro Interactions of Biomedical Polyurethanes with Macrophages and
Bacterial Cells," Journal of Biomaterials Applications
16(3):191-214) without at the same time impairing immune function
that would continue to ward off infection throughout the life of
the implant, polyurethanes in base-tubes, wedges, and outer
encapsulating coatings thereof incorporate silicone into the soft
segments and/or such surface modifying endgroups as further
research will establish to be effective (Matheson, L. A., Santerre,
J. P., and Labow, R. S. 2004. "Changes in Macrophage Function and
Morphology Due to Biomedical Polyurethane Surfaces Undergoing
Biodegradation," Journal of Cellular Physiology 199(1):8-19; Jones,
J. A., Dadsetan, M., Collier, T. O., Ebert, M., Stokes, K. S.,
Ward, R. S., Hiltner, P. A., and Anderson, J. M. 2004. "Macrophage
Behavior on Surface-modified Polyurethanes," Journal of
Biomaterials Science, Polymer Edition 15(5):567-584; Christenson,
E. M., Dadsetan, M., and Hiltner, A. 2005. "Biostability and
Macrophage-mediated Foreign Body Reaction of Silicone-modified
Polyurethanes," Journal of Biomedical Materials Research Part A
74(2):141-155; McBane, J., Santerre, P., and Labow, R. 2005. "Role
of Protein Kinase C in the Monocyte-derived Macrophage-mediated
Biodegradation of Polycarbonate-based Polyurethanes," Journal of
Biomedical Materials Research Part 74(1):1-12).
[1896] To kill any bacteria that adhere to the implant after
removal from the sterile package and before insertion, the implant
is wetted with an antiseptic that specifically omits ciclosporin
(cyclosporine) or any other immunosuppressant (see, for example,
Thorat, S. P., Thane, U. M., Pai, N., and Dahanukar, S. A. 1994
"Inhibition of Phagocytes by Cyclosporin in Vitro," Quarterly
Journal of Medicine 87(5):311-314). Closely related research that
relates to controlling the rate rather than the warding off of
degradation pertains to materials for replacement through breakdown
and cellular infiltration for tissue integration or where the
object is to accelerate absorption (see, for example, Hong, Y.,
Guan, J., Fujimoto, K. L., Hashizume, R., Pelinescu, A. L., and
Wagner, W. R. 2010. "Tailoring the Degradation Kinetics of
Poly(ester Carbonate Urethane)Urea Thermoplastic Elastomers for
Tissue Engineering Scaffolds," Biomaterials 31(15):4249-4258;
McBane, J. E., Santerre, J. P., and Labow, R. 2009. "Effect of
Phorbol Esters on the Macrophage-mediated Biodegradation of
Polyurethanes via Protein Kinase C Activation and Other Pathways,"
Journal of Biomaterials Science. Polymer Edition
20(4):437-453).
[1897] I7a(4). Nonmagnetized Base-Tube and Double-Wedge
Shield-Jackets
[1898] As shown in FIGS. 4, 5, and 10, to protect the fine vessels
and nerves of the adventitia, the stent-jacket is provided with a
lining of visco-elastic polyurethane, or temper moisture
barrier-coated viscoelastic polyurethane foam. Placement of the
jacket may result in injury to few in circumferential complexes in
the way of the edges of the side-slit or side slot, not the
majority that arise in the lumen and run longitudinally along the
surface of the ductus wall, and those injured soon regenerate. The
fenestrations or perforations through the jacket afford clearance
for fine structured aligned to these. Further to leave intermittent
segments of the ductus unencircled with no fine structures in these
segments, the stent-jacket can be sectional as addressed below in
the section entitled Sectional Extraluminal Stents, Segmented and
Articulated or Chain-stents.
[1899] For durability and retention of mechanical properties, the
foam is of high density. In a specific application, the foam can be
surface-wetted or saturated with any liquid medication or coated
with any in the form of a paste. Ordinarily, the stent-jacket is
placed after the intraductal implants have been placed and
therefore plays no part in the physics of ballistic implantation.
Means for the recovery of a miniball when the jacket is
nonmagnetized include the recovery electromagnets, a trap-jacket
and/or an extracorporeal electromagnet with probe prepositioned
downstream, and an embolic filter. Unlike a stent-jacket, the
resilience and/or thickness of the polymers of each wedge or the
adjacent segments comprising each wedge in a double-wedge insert
lining for a shield-jacket need not be specified for the strength
of magnetization.
[1900] Reasons for placing the stent-jacket before initiating
discharge are addressed above in the section entitled Circumstances
Recommending Preplacement of the Stent-jacket. Preplacing a
stent-jacket with more powerful magnetization can result in abrupt
displacements (yanking, jerking, deflection) of the muzzle-head,
interfering with the accuracy of discharge. The problem is more
likely with a stent-jacket having more powerful spaced apart
(discrete extrinsic) bar magnets mounted about the outer surface of
the base-tube, the need for which is exceptional and can often be
avoided by using a more uniformly magnetized intrinsically or
quasi-intrinscally magnetized stent-jacket. When the stent-jacket
is the end-implant and its magnetization does not pull at the
muzzle-head as interferes with achieving accuracy, it is preferable
to preposition it from the outset, avoiding the additional risk of
adventitial injury and irritation to the access wound.
[1901] Otherwise, a nonmagnetized temporary shield which has to be
removed and replaced with the magnetized end-implant stent-jacket
before closing is used. Using a muzzle-head of larger diameter
reduces but does not eliminate abrupt yanking, but in some
arteries, will obstruct circulation forcing hurried completion and
withdrawal or cardiopulmonary bypass. When a multibarrel
radial-discharge barrel-assembly is moved and discharged at high
rate under the control of a positional control system, the
preplaced stent-jacket will almost invariably be
quasi-intrinsically and therefore more uniformly magnetized to no
greater strength than is necessary to retract the lumen wall,
reducing the problem to a level that can be adapted to and
tolerated.
[1902] When it does occur, such deflection is sudden and unexpected
as to permit response only after encountered and sometimes with
limited ability to be counteracted by carefully repositioning the
muzzle-head, adjusting the recovery electromagnets in the
muzzle-head or with the aid of an extracorporeal electromagnet, or
if necessary, withdrawing and reentering with a larger muzzle-head.
When greater retractive force is required, however, the number of
miniballs discharged and not positioned as desired may be
significant, placing miniballs too closely together or bunched,
causing a perforation. The field strengths (amplitudes,
intensities) of the recovery electromagnets are continuously and
separately adjustable and the polarities reversible, but bipolar.
This is inherent and essential to allow the fields to be directed;
however, bipolarity is eccentric rather than circumferential or
radially symmetrical.
[1903] Unless exactly counterbalancing the pull, adjustments to
greater field strengths than those of the jacket will only reverse
the direction of the deflection and risk the extraction of
miniballs already placed. Therefore, absent a compelling reason,
such as those addressed above in the section entitled Circumstances
Recommending Preplacement of the Stent-jacket, preplacement of a
magnetized stent-jacket is deferred until after implantation, the
provisions of the section above entitled Sequence of Stent-jacket
Placement and Implantation in Relation to Trap-extractor (Recovery)
Electomagnet Susceptibility and Field Intensity tried, or a
temporary nonmagnetized shield-jacket used. When the only reason
for placing a magnetized jacket, that is, a stent-jacket, prior to
initiating discharge is to protect against perforations, the
consequences of a perforation should be assessed, and if the
preceding measures are decided against, the use of stays should be
considered.
[1904] When higher density circumferential implantation is desired
to obtain a more closely and uniformly placed formation of
miniballs that will distribute the tractive force more evenly, the
use of a perforation shield-jacket may be justified. This is
usually the case when discharge is automatically executed under
machine control at a rate that precludes stopping in time to
intervene before many miniballs have been discharged. A perforation
type shield-jacket is a temporary nonmagnetized base-tube or
double-wedge lined jacket placed during implantation discharge and
replaced with the magnetized stent-jacket as the absorbable or
nonabsorbable end-implant before closing. Shield-jackets that
include sufficient continuous ferromagnetic matter can provide
warming of the substrate ductus by magnetic or electromagnetic heat
induction.
[1905] Perforation shield-jackets are unusable as radiation
shield-jackets, which are usually introduced as the outer
absorbable layer of a laminated stent-jacket that must remain until
decay has progressed to a level safe for surrounding tissue,
whether dissolution is spontaneous or on demand, as addressed above
in the sections entitled Implants that Radiate Heat on Demand and
Noninvasive dissolution on demand of absorbable stent-jackets,
base-tubes, radiation shields, and miniballs. Nonmagnetized
radiation and perforation shield-jackets for use along the vascular
tree usually depend upon a downstream external electromagnet and/or
an impasse-jacket to intercept a miniball that accidently enters
the circulation.
[1906] I7b. Stent- and Shield-Jacket Moisture Barrier-Coated
Viscoelastic Polyurethane Foam Linings
[1907] Viscoeleastic polyurethane foam is addressed above in the
sections entitled Presliminary Description of the Invention and
Requirement for Moisture barrier-coated viscoelastic polyurethane
foam Linings. Stent-jackets, shield-jackets, the inner wedge of
double-wedge linings, impasse-jackets, and some magnet- and
clasp-jackets have an inner lining of higher density moisture
barrier-coated viscoelastic polyurethane foam. Even in
nonhyperlipidemic subjects, obstruction of the vasa vasora by
compression results in medial and intimal hypoxia and the
undernutrition of cells in the luminal wall that leads to cellular
necrosis and its associated immune response whereby leukocytes
infiltrate the intima producing the chronic inflammation of
atherosclerosis and endothelial dysfunction that impairs vasotonic
control (references provided above in the section entitled
Accommodation of the Adventitial Vasculature, Innervation, and
Perivascular Fat).
[1908] Avoiding this disease process initiated by circumvascular
compression is accomplished by providing the stent-jacket with a
slit so that it expands and contracts with the ductus and affords
an opening to the surrounding medium; perforations along the side;
and by lining the stent-jacket with moisture barrier-coated
viscoelastic polyurethane foam (low resilience polyurethane foam,
visco-elastic polyurethane foam), which enfolds rather than
compresses the vasa vasora and nervi vasora, whether the foam
itself is compressed. Regardless of type, the lining is bonded to
the inner surface of the outer layer or layers of the jacket after
those have been encapsulated together for chemical isolation as an
added precaution against any leakage of lanthanoid and attack by
the immune system. The unencapsulated inner layer of moisture
barrier-coated viscoelastic polyurethane foam is protected by the
chemical Materials Suitable for Rebound-directing Double-wedge
Linings.
[1909] The shape compliance of the foam is enhanced by the warmth
of the internal environment and at the outer surface of the
encircled ductus. Especially dense vasa provide greater warmth and
are least disturbed or stifled by heat entrapment through the use
of stent-jackets that minimize ensheathment by providing apertures
or chain-stents that link the substents at intervals where the
ductus is not encircled. The lining provides several advantages, to
include accommodating small structural projections that as part of
the stent-, impasse-, or shield-jacket would otherwise protrude
into the adventitia, accommodating the out of roundness along a
larger stent-jacket expansion insert used when the ductus is
interim swollen.
[1910] This is addressed below in the section entitled Stent-jacket
Expansion Inserts, and latitude in diameter that eliminates the
need to recover a deliberately oversized jacket placed in later
childhood for replacement following growth. In some instances where
the wall of the ductus is too thin or weak to accommodate the
placement of an extraluminal stent but is intimately associated
with and adherent to surrounding tissue, it is possible to include
a thickness of the surrounding tissue within the stent or jacket.
One method for predetermining such a condition is intravascular or
intraductal ultrasound. Thin walled veins are not susceptible to
atherosclerosis; however, veins are suitable for the placement of
impasse-jackets, which can include some surrounding adherent tissue
when the vein itself is weak or weakened by disease.
[1911] The no-touch technique for harvesting the saphenous vein
(see, for example, Sepehripour, A. H., Jarral, O. A., Shipolini, A.
R., and McCormack, D. J. 2011. "Does a `No-touch` Technique Result
in Better Vein Patency?," Interactive Cardiovascular and Thoracic
Surgery 13(6):626-630; Dashwood, M. R., Savage, K., Tsui, J. C.,
Dooley, A., Shaw, S. G., Fernandez Alfonso, M. S., Bodin, L., and
Souza, D. S. 2009. "Retaining Perivascular Tissue of Human
Saphenous Vein Grafts Protects Against Surgical and
Distention-induced Damage and Preserves Endothelial Nitric Oxide
Synthase and Nitric Oxide Synthase Activity," Journal of Thoracic
and Cardiovascular Surgery 138(2):334-340; Rueda, F., Souza, D.,
Lima Rde, C., Menezes, A., Johansson, B., and 5 others 2008. "Novel
No-touch Technique of Harvesting the Saphenous Vein for Coronary
Artery Bypass Grafting," [in English] Arquivos Brasileiros de
Cardiologia 90(6):356-362) would appear to recommend minimizing
direct contact with and handling of the vein even when unaffected
by disease. For placing an impasse-jacket, the incision is not more
than a few centimeters in length and a small fraction the length
required to harvest the vein.
[1912] Conditions that would recommend the use of a stent in very
young patients are rare and seldom long term. When the stent-jacket
is placed prior to discharge, the interaction between the jacket,
the diseased tissue it encircles, and the forces generated by
discharge make for a more complex set of variables than when a
jacket is uninvolved. Susceptibility to perforation due to
degradation in the elasticity of the ductus is determinable using
the testing procedure described below in the section entitled Test
upon Endoluminal Approach for Susceptibility of the Ductus Wall to
Puncture, Penetration, and Perforation and agents for causing the
ductus wall to thicken under the section below entitled Attainment
of Implantable Intramural Thickness. The jacket is made to a high
standard of consistency, but missing a significant spot in in situ
testing can result in nonfunctional positioning of miniballs if not
entry into the lumen.
[1913] In any stent-jacket or perforation type shield-jacket, the
moisture barrier-coated viscoelastic polyurethane foam lining must
be thick enough to entrap a perforating miniball without allowing
it to rebound. A double-wedge lining has the more complex function
of trapping and decelerating a miniball that enters with
insufficient momentum to rebound, but imparting a functional angle
without excessive deceleration of a miniball that enters with
sufficient momentum to rebound. A functional angle of rebound is
imparted by the more resilient bounce-surface of the outer wedge of
the double-wedge insert lining, and less often, by the inclined
inner surface of the base-tube so that the insert lining includes
only the foam wedge. In either case, the inner wedge of moisture
barrier-coated viscoelastic polyurethane foam is of continuously
changing thickness where the momentum on entry determines whether
the miniball will be trapped or rebounded into the wall of the
ductus.
[1914] Notwithstanding this variation in thickness, the foam must
be thick enough to trap and retain a miniball that enters without
protrusion into the adventitia, but thin enough to avoid absorbing
too much momentum as would trap or improperly redirect a miniball
of sufficient residual momentum to be rebounded to a functional
location in the wall. To achieve this uniformity and avoid the need
for a jacket of larger diameter as would encroach upon the
surrounding tissue, when necessary, the foam wedge is assembled
from adjacent segments of density to offset the difference in
thickness. The resilience and/or thickness of the moisture
barrier-coated viscoelastic polyurethane foam in a double-wedge
lining insert must take into account whether the insert is to be
used in a magnetized stent- or a nonmagnetized shield-jacket. The
contribution to acceleration of a miniball nearing and deceleration
when rebounding away from more powerful magnets vary according to
the strength of magnetization.
[1915] If significant, the magnetic force can retard a rebound that
would otherwise have resulted in a functional positioning of the
miniball. To avoid such interference due to a needlessly powerful
magnetic field, as well as to minimize the risk of pull-through or
delamination, magnet selection is primarily based upon achieving
luminal patency on a long-term basis with the minimum field
strength necessary to maintain and secondarily on obtaining
uniformity of attraction over the segment encircled. The resilience
and/or thickness of the polymers of each wedge or the adjacent
segments comprising each wedge in a double-wedge insert lining for
a stent-jacket must be specified for the strength of magnetization.
Neither the internal inclined or rebound surface of the outer wedge
or of the base-tube nor the inner or outer surfaces of the foam
wedge need ever require lamination with or an additional layer of
another material to increase or decrease its resilience.
[1916] I7c. Stent- and Shield-Jacket Anti-Migration Linings
[1917] Migration is a concern with stent-jackets, which are
implanted to remain in place for an indeterminate period if not
life, but not temporary jackets such as perforation shield-jackets,
which remain in use during discharge and perhaps a relatively short
ensuing period when a shield-jacket capable of being warmed by heat
induction is used for that additional purpose. When the outer
surface of the stent- or shield-jacket is not in contact with
neighboring tissue that moves in relation to it, the moisture
barrier-coated viscoelastic polyurethane foam lining, end-ties,
side-straps, and if a stent-jacket, the magnetic attraction on of
the ductus-mural implants prevent migration, or the longitudinal
displacement of the jacket along the ductus.
[1918] In most instances, the moisture barrier-coated viscoelastic
polyurethane foam lining alone will afford sufficient resistance to
lateral displacement so that no additional anti-migratory measures
such as impressing the surface of the foam with a deep surface
texture or overlaying the foam with gauze is necessary. Guaze used
for this purpose should readily stretch and detract from the
ability of the moisture barrier-coated viscoelastic polyurethane
foam to enwrap the adventitial microstructures as little as
possible. However, when the outer surface of the jacket is in
moving contact against neighboring tissue so that side-straps rub
against and abrade the tissue, the risk of erosion or fistulization
to the neighboring tissue and migration of the jacket become
concerns. If necessary, as when end-ties are not wanted,
nonallergenic gossamer grade woven surgical gauze is bonded by
means of a plastic adhesive to the inner surface of the moisture
barrier-coated viscoelastic polyurethane foam regardless of whether
the foam is the inner wedge of a rebound-redirecting
double-wedge.
[1919] To avoid brittleness that would cause the gauze to become
stiff, irritate the adventitia, and eventually disintegrate through
the accumulation of microfractures, a surgically acceptable
adhesive that remains pliable after curing, such as one
polyurethane based (see, for example, Marois, Y. and Guidoin, R.
2001. "Biocompatibility of Polyurethanes," in Vermette, P.,
Griesser, H. J., Laroche, G. and Guidoin, R. (eds.), Biomedical
Applications of Polyurethanes, Austin, Tex.: Landes Bioscience) is
used. The adhesive should be absorbed into or adsorbed onto the
fabric of the gauze without filling the interstices as too thick or
filming due to surface tension as too thin. The adhesive is applied
to the gauze at isolated spots at the periphery of the lining, the
number kept to the minimum to least detract from the ability of the
foam to comply with the surface anatomy of the adventitia, any
filming over of gauze openings removed.
[1920] Suitable adhesives are specified below in this section. The
delayed healing that has been observed with polyurethanes may be
pertinent only when a stent-jacket with gauze covered lining is
positioned prior to discharge. Accordingly, end-ties and where
nonencroaching on neighboring tissue side-straps are preferable for
prepositioned stent-jackets. When the jacket is placed after
implantation, stay incision flaps or any perforations created
during discharge will already have sealed. The stay incisions would
already have been bonded shut by the tissue bonding agent dispensed
by the tool onto the emerging stay, and a perforation would have
been sealed almost entirely by the endoplasm released by the cells
along the trajectory, blood, or serous fluid.
[1921] Thus, before the stent-jacket is placed, the external
surface of the ductus recovers to a condition sufficiently intact
to place the jacket despite previous microincisions or
perforations. A perforation shield-jacket placed just prior to
discharge or following stay insertion which contains sufficient
continuous ferrous content to heat noninvasively by heat induction
can be warmed to accelerate the coagulation of the exudates and
body fluids that enter the perforation trajectories or the initial
setting of the stay insertion incision bonding (infibulating,
fusing) adhesive. The gauze is taken up by the foam but presents a
grating in contact with the adventitia that resists migration, and
may be enhanced by tissue infiltration. The base-tube is provided
with `breathing` holes or perforations for exposure to the
environment.
[1922] When, exceptionally, a perforation could lead to a serious
consequence such as striking a vulnerable ganglion, a
rebound-directing or double-wedge lining, as described in the
section above entitled Double-wedge Stent- and Shield-jacket
Rebound-directing Linings, is used. With a ureter, which has an
outer fibrosa, or a fallopian tube, an outer serosa, for example,
the outer layer is not so densely innervated or supplied with
vessels that a foam lining is necessary to protect this fine
structure. The lining then serves as a perforation trap and
anti-migration feature, whether in a straight line or double-wedge
stent-jacket. For this reason, stent- and shield-jackets include a
foam insert lining rather than an internal surface that is made
only resistant to displacement by having been rib or ridge textured
through embossing or the insertion and bonding of a grid, for
example.
[1923] Imparting a deeply textured internal surface to the foam by
relief or embossing increases its anti-migratory traction. When the
stent-jacket is positioned prior to initiating discharge, the
materials and conformation of a straight line lining prevents
rebounding by entrapping the miniball. If of the double-wedge type,
lower momentum miniballs are trapped but higher momentum ones
rebounded to a ductus-intramural terminus that preserves function.
The protective foam lining should come up to the edges of the
side-slit or side-slot. Since any stent-jacket should include a
protective lining that extends entirely to the edges of the
side-slit or side-slot, the expansion insert is bonded along the
slit or slot interface and a lapped over portion that extends a
short distance along the outer surface of the jacket.
[1924] Expansion inserts of greater length include a straight-line,
not a double-wedge, moisture barrier-coated viscoelastic
polyurethane foam lining. An anti-migration deep texture surface
pattern can be cut into the inner polyurethane moisture
barrier-coated viscoelastic polyurethane foam layer of a double
wedge lining or gossamer gauze applied to its adventitial contact
inner surface. When the base-tube of the stent-jacket is made, for
example, of Bionate.RTM. thermoplastic polycarbonate urethane
copolymer tubing and a rebound lining as described above is not to
be inserted, the gauze can be glued directly to the inner surface
of the foam lining.
[1925] Suitable adhesives for bonding the gauze to the surface at a
few isolated spots include plasticized long carbon chain
cyanoacrylate cements, such as 2-octylcyanoacrylate, 4
Meta/MMA-TBB.RTM. 4-metacryloyloxyethyl trimellitate anhydride
(4-META), prepared using methylmetacrylate (MMA) as monomers and
tri-n-butyl borane (TBB) as an initiator, Histoacril.RTM.
2-cyanobutylacrylate, and Bucrylate.RTM. isobutylcyanoacrylate.
Cyanoacrylate cement used to seal adventitial entry incisions
produced by stay insertion (addressed below) are eventually broken
down or absorbed and can be drug-releasing before infiltrated and
replaced by tissue.
[1926] The placement of a double-wedge stent- or shield-jacket
lining with a textured or gauze overlain surface to serve as an
anti-migration lining prior to discharge in order to prevent a
perforation from striking neighboring tissue should take into
account the effect, if any, of the gauze or textured pattern on the
rebound and trapping characteristics on the miniball. Different
gauzes, mesh thicknesses, hole sizes, and adhesives can produce
different rebound characteristics. If the range of rebound variance
exceeds that tolerable or results in unacceptable rebounds in too
high a percent, end-ties, addressed in the section that follows,
must be depended upon to prevent migration.
[1927] I8. Radiation Shielded Stent-Jackets
[1928] Radiation shield-jackets, addressed above in the section
entitled System Implant Magnetic Drug and Radiation Targeting, are
distinct, whereas radiation shielding stent-jackets have an outer
laminated layer bonded about an intrinsically or
quasi-intrinsically magnetized stent-jacket. Shield-jackets used to
prevent a perforating miniball from striking adjacent tissue rather
than to allow postprocedural warming by noninvasive magnetic or
electromagnetic heat induction are removed after discharge
implantation before irradiation is allowed an interval for
antiproliferative (antimitotic) or antiangiogenic or other
antineoplastic uptake and are not radiation shielded.
[1929] The shield layer comprises an absorbable or degradable
matrix containing heavy metal shielding particulate. To allow
compliance when the shield is directly laminated to the outer
surface of the stent-jacket, the shield must also be slit and
rotated to the side opposite the source of radiation. The problem
of a shield that to be compliant must leak is reduced by
interposing closed cell moisture barrier-coated viscoelastic
polyurethane foam cuffs at either end between stent-jacket and a
larger diameter shield that does not expand and contract along with
the stent-jacket it encircles and by extending the jacket and
shield beyond the segment affected, gas exchange or `breathing`
afforded by the fenestrae.
[1930] Such a shield must be slit to fit over the ductus, but the
slit is sealed with a suitable cement, usually cyanoacrylate. The
digestive tract having to expand during the course of normal
function, sufficient clearance is usually available to place such a
larger diameter closed shielded stent. In a spine and
ribs-configured stent-jacket placed along the esophagus, provided
the thickness of the cuffs accommodate the expansion of a passing
bolus, this allows the free and independent movement of the ribs
within the outer shield. The matrix must be elastic for compliance
with the expansion and contraction of the ductus, slit or slotted
in alignment with the subjacent stenting, and the particulate
elongated and overlapped or imbricated as least to detract from
elasticity.
[1931] The particulate can consist of tungsten, gold, and/or
osmium, for example, but not lead, platinum, or rhodium, which in
such small quantity lack sufficient shielding effect. A shield for
high dose-rate ductus-intramural implants with a long half-life to
be the removed in a followup procedure at a time to be determined
by imaging inspection so that the time is not predictable
incorporates ferrous wire to allow breakdown on demand by heat
induction. Brachytherapy that confines radiation to the lesion most
damages targeted hyperproliferative and least damages nontargeted
normoproliferative cells. The radiation can be delivered by seed
stays or miniballs implanted within the wall of the ductus or by
seed miniballs arrested in place within the lumen by a strongly
magnetized stent-jacket with a radiation shield.
[1932] An impasse-jacket is designed to allow the noninvasive
extraction of miniballs whether endoluminally suspended or
ductus-intramurally implanted and is compatible with an the outer
radiation shield layer only when the outer layer is destructible on
demand by heat induction to expose the extraction grid to the
extracorporeal extraction electromagnet, as addressed below in the
section entitled Stereotactic Resituation of a Mispositioned
Miniball, among others. Impasse- and more strongly magnetized
stent-jackets with or without a radiation shield are suitable for
suspending miniballs that release chemotherapeutic agents at the
target segment. If the drug is carrier nanoparticle bound, the
jacket will suspend the miniballs in place, may assist in miniball
dissolution, and draw the drug into the wall of the ductus.
Combined radiation and chemotherapy are obtained by interspersing
seed and drug-releasing ductus-intramural implants.
[1933] I9. Jacket End-Ties and Side-Straps
[1934] A stent-jacket to be positioned at a site especially prone
to migration has side-straps and/or end-ties added toward either
end. Side-straps wrap around the jacket to elastically cinch and
tighten its grip. Unlike end-ties or end-straps which stabilize the
jacket in longitudinal position by tying directly to the ductus off
to the sides of the jacket, side-straps tie about the jacket.
Side-straps must therefore be fitted with the ductus quiescent and
adjusted to not detract from compliance to expansion by adding
significant resistance. Temporarily tightening a collar about a
ductus such as side-straps, end-ties, or end-straps is a local or
targeted means for suppressing ductus intrinsic or pulsatile
motility that detracts from accuracy during discharge
implantation.
[1935] A shield-jacket is rarely left in place long enough for
migration to result. A shield- or stent-jacket with side-straps,
end-straps, or end-ties placed before initiating discharge for the
primary purpose of stopping and containing a perforating miniball
can serve a secondary purpose of stabilizing the ductus to allow
greater accuracy of implantation discharge, as well as a third
purpose of allowing the jacket to be warmed by induction heating
when the jacket contains sufficient continuous ferrous material.
Side-straps can be rotated at the rivet fastening these to the
jacket to serve as end-straps; however, to do so fails to achieve
more secure stabilization or satisfy the requirement of end-ties,
which is to achieve stabilization with little increase in jacket
diameter.
[1936] Side-straps are made of braided multifilament spandex fabric
woven loosely as to least interfere with breathability as a backing
for hook and loop (touch-, burr-, Velcro.RTM.) fasteners, the hooks
at the end on one side and loops on the other side of the backing.
The spandex in side-straps should add as little as possible to
resistance of the jacket to expansion. Side-straps are generally
lined with segments of moisture barrier-coated viscoelastic
polyurethane foam on the internal surface of the spandex backing
that separate if the spandex is stretched.
[1937] End-ties are off-to-either-end outrigger tethers or
end-tethers used as longitudinal position stabilizers at sites with
inadequate periductal clearance for side-straps, which become
thicker when not stretched and would protrude into, rub against,
possibly erode, or even fistulize neighboring tissue. Only the hook
and loop fastening end tab of the suture end-tie is made as are
side-straps, and end-ties are fastened off to the sides rather than
around the jacket. Except for the end fastening tab, end-ties are
made of soft braided and loosely woven multifilament suture, such
as Neobond.RTM., coated polyester, or Durasil.RTM. silk suture,
which is specified for absorbability (spontaneous dissolution
responsive to enzymatic or hydrolytic action) or nonabsorbability,
as is the jacket to which the end-ties are connected.
[1938] I9a. Form of End-Ties
[1939] Where a lack of clearance prompts the avoidance of
side-straps, end-ties of woven (braided, multifilament, stranded)
suture are used. Silk suture exhibits good elasticity but must be
avoided in silk hypersensitive (allergic) patients, synthetic
suture used in lieu thereof. The use of hard monofilament suture is
discouraged. For a jacket of given length, end-ties pose the
disadvantage of requiring a longer entry incision to apply. Other
disadvantages of end-ties as compared to side-straps is that more
time is necessary to fix the jacket in position with forceps.
Suture is used only for tie lines, never to attach directly to the
ductus, which even when attached with multiple turns, is likely to
constrict, irritate, and could even strangulate the ductus.
[1940] As are lining and expansion inserts, side-straps and
end-ties are usually attached to a jacket on an as needed basis.
This allows tailoring of the jacket to the specific site and jacket
standardization that reduces the production cost. Spandex
side-straps and end-tie suture are fastened to the jacket, and
end-tie suture fastened to the spandex end-tab that grasps the
ductus, in the same way. The end connecting tabs of end-ties are
made of the same layers as are the end-straps of a segmented stent
but are attached not to the jacket but rather to suture that is
attached to the jacket, and to clearly distinguish the two, are
referred to as end-tabs, not end-straps. The term `outrigger` also
pertains to off at the ends impasse-jacket anchors, and should be
qualified as pertaining to end-tie or impasse-jacket
outriggers.
[1941] End-tabs A punch and riveting hand tool is used to insert
wide-head nonbioabsorbable biocompatible rivets, such as of
tantalum, toward the ends of the jacket or end-tab. To anchor the
spandex band of a side-strap, the spandex is flush riveted against
the jacket, and the suture of an end-tie wound about and knotted
beneath the rivet head before the rivet is closed. The wires used
to connect the jackets in articulated type chain stents are
fastened toward the ends of the separate sections or substents in
the same way as are end-straps to the extension tabs, the suture to
the base-tube and to the ductus connecting, the difference between
end-ties and segmental jacket connecting wires being that end-ties
are made of suture.
[1942] The end-tabs of end-ties that cinch about the ductus must
not be so narrow that the spandex backing digs into, cuts into, or
constricts the ductus or is able to slide along the ductus without
being made too tight or so that too few hooks and loops secure the
straps in position. End-tie end-tabs for cinching the suture about
the ductus are no different than side-straps in having a
stretchable backing of spandex, hooks and loops on opposite sides
and opposite ends of the tab, with portions of the tab in contact
with the ductus lined with moisture barrier-coated viscoelastic
polyurethane foam segmented as necessary to stretch with the
spandex and faced with heavy gauged gossamer gauze to hold fast. As
depicted in FIGS. 13 and 14, a unit stent-jacket cut from a
continuous segmented-type chain-stent has tabs that project past
the rest of the ends of the base-tube.
[1943] Such hook and loop end-tab fastening straps are made as are
side-straps and fastened to the base-tube extension tab at each end
by means of rivets, but cinching about the ductus rather than the
jacket, are not side-straps, and not made of suture, are not
end-ties, but rather end-straps. As many jacket segments as
necessary are cut from the continuous strip, so that such a
segmented jacket is able to follow an inflamed ductus however long
or bending although increased length and bends necessitate wider
exposure. To preclude the end corners and edges of the extension
tabs from protruding into the adventitia, the moisture
barrier-coated viscoelastic polyurethane foam lining with or
without gauze facing within the main or circular part of the
elastic polymeric base-tube is not discontinued along the inside of
the tab.
[1944] Side-straps and end-straps may be singular so as to wrap
entirely about the ductus and secure with hooks at the inside end
of the strap and loops along the outside over the length where the
hooks attach or double, so that the inner end segment of one has
hooks and the outer face of the other loops. Since these are added
for the application, either singular (unilateral) or double
(bilateral, opposed) straps are chosen as allows placement most
efficiently for the specific site. Whether one-sided (unilateral)
or opposed (bilateral), straps or end-tie connecting tabs are kept
as short as allows the ductus to be cinched securely and
nonconstrictively without nonessential doubling or overlapping.
[1945] This is especially the case when the connecting hook and
loop segments include the moisture barrier-coated viscoelastic
polyurethane foam layer, which detracts from stretchability, hence,
compliance to the action in the ductus as well as detracts from the
surrounding clearance. For this reason, straps placed where
clearance is minimal should be no longer than allows secure
fastening, with the moisture barrier-coated viscoelastic
polyurethane foam layer omitted from the hook and loop connecting
segments. So that a nonoverlapped portion will be free to stretch
in compliance, strap length is set for the quiescent circumference
of the ductus. Due to the force of expansion of the ductus and the
lack of resistance to the force of the side-slit or side-slot, a
stent-jacket can vary over a range of elasticity without
significant effect upon the substrate ductus, making stent-jackets
usable with different type ductus of suitable diameter.
[1946] I9b. Use of End-Ties
[1947] The operator fastens the belt-straps when the ductus is
quiescent or, if an artery, during diastole, being certain not to
pull at so as to stretch the spandex-backing before engaging the
hooks and loops. As addressed below in the section entitled
Motional Stabilization of the Implant Insertion Site, when
miniballs rather than stays are used so that the jacket can be
positioned prior to implantation discharge, the stent-jacket can be
used with or without drugs to suppress a pulse that is too fast
and/or irregular to allow accuracy. The jacket is temporarily
tightened during discharge and thereafter loosened to the
functional tautness, which is confirmed before closing.
[1948] For this reason, the concurrent use of a cardioplegic or
autonomic function suppressing drug such as an opioid or
anticholininggic is deferred until the long-term tautness has been
ascertained. Magnetic stent-jackets generally use end-ties or if
segmented, end-straps, which are located past the ends of the
jacket and fastened directly onto the substrate ductus, whereas
nonmagnetic stent-jackets use side-straps, which gird about the
stent-jacket itself. Unlike shield- and stent-jackets, to which
straps and ties are added only when the location for positional
stabilization poses a greater risk of migration, clasp-wraps and
magnet-wraps lack a resilient layer and the binding value of
attraction between intravascular and extravascular components, and
are therefore secured by means of side-straps included in their
basic structure.
[1949] When a stent-jacket had included an expansion insert since
absorbed or lithotripsied as described below in the section
entitled Expansion Inserts Absorbable, Meltable, and Comminutable
for Time-discrete Decremental Contraction of Stent-Jackets, to have
used side-straps toward the ends of the base-tube would add the
strap stretching resistance to the resistance to expansion of the
base-tube, and following contraction, the belt-straps would be
loose. Since side-straps are not compatible with expansion inserts,
end-ties are used instead. Also incompatible are side-straps that
overlap rather than pass between discrete or separate magnets
mounted about the outer surface of the base-tube, although, the
fact that side-straps close about the jacket rather than the
ductus, and for that reason, can often be made narrow enough to do
this.
[1950] Side-straps that lap over the magnets will often produce an
outer diameter for which sufficient clearance is lacking, and if
too tight, can cause a thin base-tube to bulge inward. Spaced apart
magnets are used where intense field strength is required; more
often the distribution of evenly distributed minimal attractive
force is appropriate and obtained with a quasi-intrinsically or
intrinsically magnetized stent-jacket, which will usually admit of
the added diameter. When side-straps would add too much to the
diameter or affect the resultant resistance to stretching or the
effective resilience of the jacket in response to the intrinsic
expansion of the ductus, end-ties are used instead; the thickness
or material of the base-tube is not changed to offset the use of
thicker side-straps.
[1951] Articulated type chain-stents attached by wires usually
stabilize each other; however, if intermediate anti-migration
anchoring is desired, side-straps are connected with the same wide
head rivets as fastens the wires or strong suture used to connect
the substents. An chain-stent positioned along a flexing ductus is
generally tethered at both its intermediate and terminal or end
stent-jackets (end-stents) by end-straps if segmented or by
terminal end-ties and if necessary, intermediate side-straps if
articulated. The same wide-head rivets are used to secure both the
side-straps and interjacket connecting wires. To prevent premature
hook and loop connection during placement, a strip of
pressure-sensitive tape is applied to either the hooks or loops
before the jacket is inserted through the entry portal. As is the
stent-jacket itself, side-straps are fitted to the ductus during
diastole or smooth muscle inaction for expansion with the pulse or
peristalsis as pertinent.
[1952] I10. Absorbable Extraluminal Magnetic Stent-Jackets and
Materials
[1953] I10a. Absorbable Base-Tube and Stent-Jacket, Miniball, Stay,
and Clasp-Magnet Matrix Materials
[1954] An absorbable extraluminal magnetic stent-jacket is intended
to maintain luminal patency without contact, the imposition of
significant stress upon, or deformation of the internal
(endothelial) surface of the lumen while the ductus heals and then
disintegrate. It consists of subadventitially or subfibrosally
placed miniballs and a stent-jacket that consist of an absorbable
polymeric material of the kind used to make tissue enginnering
scaffolding and absorbable suture, as specified in the section
below entitled Absorbable Stent-jacket Expansion Insert Materials
with Relatively Short Breakdown Times, among others (see, for
example, Nair, L. S. and Laurencin, C. T. 2006. "Polymers as
Biomaterials for Tissue Engineering and Controlled Drug Delivery,"
Advances in Biochemical Engineering and Biotechnology 102:47-90;
Gunatillake, P. A., and Adhikari, R. 2003. "Biodegradable Synthetic
Polymers for Tissue Engineering," European Cells and Materials
5:1-16, available at
http://www.ecmjournal.org/journal/papers/vol005/pdf/v005a01.pdf).
[1955] The miniballs include nonmagnetized superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder and
the stent-jacket small magnetized neodymium lanthanoid grains or
particulate encapsulated for permanent chemical isolation, usually
within gold. Absorption may be spontaneous or as addressed in the
section that follows, forced on demand. The need for an outer
magnetized base-tube or stent-jacket is associated with a stenting
and/or a drug carrier nanoparticle-attracting function. The large
number of biocompatibility absorbable polymers afford a range of
persistence in the internal environment, or degradation profiles
that include bulk and surface erosion, sufficiently extensive to
negate the need to modify these.
[1956] These include materials used in absorbable suture and tissue
engineering scaffolding, addressed below in the section entitled
Stent-jacket Expansion Inserts, which consist of polyesters,
primarily homopolymers and copolymers of poly(lactic acid) and
poly(glycolic acid) to poly(amino acids), polyanhydrides,
polyorthoesters, polyurethanes, polycarbonates, copolyesters of
e-caprolactone, trimethylene carbonate, and para-dioxanone. In
order of increasing interval pending disintegration sought,
polyurethane elements, to include the moisture barrier-coated
viscoelastic polyurethane foam lining in an absorbable or
absorbable on demand jacket, is treated to encourage, is not
treated, or is treated to prevent the formation of foreign body
giant cells that would effect its breakdown.
[1957] A light dusting of the lining with virtually any foreign
proteinaceous matter to which the patient has been determined not
to be hypersensitive will invite attack reducing persistence, while
means for discouraging the formation of foreign body giant cells on
materials containing polyurethane, such as moisture barrier-coated
viscoelastic polyurethane foam linings, are addressed above in the
section entitled Materials Suitable for Rebound-directing
Double-wedge Linings. Such treatment must be compatible with any
medication that the lining is to release. When the period required
for healing is predictable, the material of the base-tube or matrix
of a disintegrable radiation shield-jacket is selected on the basis
of spontaneously disintegrating at about the same time.
[1958] When the period required for healing is indeterminate,
materials are incorporated into the absorbable stent so that it can
be noninvasively disintegrated on demand, as addressed in the
following section. For temporary conditions, absorbable endoluminal
are preferable to nonabsorbable stents. Absorbable radiation
shields can also be used to encircle an impasse-jacket, allowing
extraction of radiation seed miniballs once depleted. Absorbable
base-tube and matrix materials with the elasticity and resilience
required are not intrinsically magnetizable (ferromagnetic),
necessitating the addition of ferromagnetic material by embedment,
doping, lamination, or coating.
[1959] Magnesium is suitable for use in a minimally compliant or
noncompliant endoluminal stent (see, for example, Erbel, R., Di
Mario, C., Bartunek, J., Bonnier, J., and 12 otherrs 2007.
"Temporary Scaffolding of Coronary Arteries with Bioabsorbable
Magnesium Stents: A Prospective, Non-randomised Multicentre Trial,"
Lancet 369(9576):1839-1840, also referred to above in the section
entitled Basic Strengths and Weaknesses of Prior Art Stenting in
Vascular, Tracheobronchial, Gastrointestinal, and Urological
Interventions).
[1960] The release of drugs during dissolution of absorbable
materials is well over a decade in the making and under continued
development (see, for example, Zhang, C., Chen, X., Liu, G., Chen,
R., and Guo, S. 2016. "Mechanism and Kinetics of Drug Release from
Poly( -Caprolactone) Based Extrudates Prepared by Hot-melt
Extrusion," Journal of Macromolecular Science. Part B, Physics
55(3):285-298; Lenzi, E. K., Novatski, A., Farago, P. V., Almeida,
M. A., Zawadzki, S. F., and Menechini Neto, R. 2016. "Diffusion
Processes and Drug Release: Capsaicinoids--Loaded Poly
(.epsilon.-caprolactone) Microparticles," Public Library of Science
One 11(6):e0157662; Almeida, M. A., Nadal, J. M., Grassiolli, S.,
Paludo, K. S., Zawadzki, S. F., and 3 others 2014. "Enhanced
Gastric Tolerability and Improved Anti-obesity Effect of
Capsaicinoids-loaded PCL [polycaprolactone] Microparticles,"
Materials Science and Engineering. C, Materials for Biological
Applications 40:345-356; Miladi, K., Ibraheem, D., Iqbal, M., Sfar,
S., Fessi, H., and Elaissari, A. 2014. "Particles from Preformed
Polymers as Carriers for Drug Delivery," Experimental and Clinical
Sciences Journal 13:28-57; Seremeta, K. P., Chiappetta, D. A., and
Sosnik, A. 2013. "Poly(.epsilon.-caprolactone), Eudragit.RTM. RS
100 and Poly(.epsilon.-Caprolactone)/Eudragit.RTM. RS 100 Blend
Submicron Particles for the Sustained Release of the Antiretroviral
Efavirenz," Colloids and Surfaces. B, Biointerfaces 102:441-449;
Puga, A. M., Rey-Rico, A., Magarinos, B., Alvarez-Lorenzo, C., and
Concheiro, A. 2012. "Hot Melt
Poly-.epsilon.-caprolactone/Poloxamine Implantable Matrices for
Sustained Delivery of Ciprofloxacin," Acta Biomaterialia
8(4):1507-1518; Lin, M., Meng, S., Zhong, W., Li, Z., Du, Q., and
Tomasik, P. 2008. "Novel Biodegradable Blend Matrices for
Controlled Drug Release," Journal of Pharmaceutical Sciences
97(10):4240-4248; Huatan, H., Collett, J. H., Attwood, D., and
Booth, C. 1995. "Preparation and Characterization of
Poly(epsilon-caprolactone) Polymer Blends for the Delivery of
Proteins," Biomaterials 16(17): 1297-1303).
[1961] Heat inductive and chemical means addressed in the following
section entitled Noninvasive Dissolution on Demand of Absorbable
Stent-jackets, Base-tubes, Radiation Shields, and Miniballs can be
used to release chemicals such as solvents incorporated into these
materials within small capsules to accelerate dissolution and/or to
release drugs, or the latter first when embedded at the surface.
Magnesium can be alloyed to convert it from paramagnetic to
ferromagnetic allowing its use in an absorbable impasse-jacket
extraction-grid, but however alloyed while still remaining
absorbable, magnesium lacks the sustained elasticity required for
compliance with ductus motility required of an extraluminal stent,
radiation shield matrix, or any other component that must not
impede the expansion and contraction of the substrate ductus.
[1962] No single material that would allow making a stent-jacket
which is intrinsically magnetized, absorbable without the
incorporation of a second material, and flexible currently
available, an absorbable quasi-intrinsically magnetized
extraluminal stent with or without an outer absorbable radiation
shield laminated is used to treat a ductus wall that is expected to
require stenting only over a limited interval. For spontaneous
dissolution, such a jacket consists of an absorbable polymeric or
copolymeric material matrix selected on the basis of prospective
absorption time with magnetized grains of lanthanoid such as of
neodymium iron boron encapsulated for chemical isolation with gold,
for example, embedded.
[1963] An absorbable radiation shield-jacket differs in
incorporating isolation encapsulated grains of tungsten or osmium,
for example, in overlapping relation to allow flexion. Since
shielding materials are not magnetizable, an absorbable jacket to
both retract subadventitial implants and to provide radiation
shielding is laminated by bonding or fusing component lamina where
the inner provides stenting and the outer shielding. Lamination and
bonding must yield a jacket or chain type jacket of suitable
flexibility for compliance with the least resistance to the
movement in and of the ductus. The absolute sum mass of elemental
iron particulate, for example, used in the implants depends upon
the size of the ductus, the field strength required to maintain it
patent, and the number of stents required.
[1964] When to allow complete absorption, iron particulate in the
miniballs or stays is not encapsulated, the iron left behind
following dissolution of the matrix or base will become toxic at
about 350 micrograms per deciliter serum iron level (The Merck
Manual of Diagnosis and Therapy, 18th edition, pages 2667-2668),
which circumstance limits the sum mass in terms of number and size
of unencapsulated iron miniballs that should be used in stenting.
Iron toxicity is avoided by encapsulating the fraction of iron
particulate that would exceed this level for chemical isolation
within an outer shell of gold, for example.
[1965] Encapsulated particulate or grains are deep surface textured
to allow and coated to encourage tissue integration. If small
enough, the entire miniball or stay is treated thus.
[1966] Alternatively, the iron particulate can be coated with
polymers that are absorbable but differ in dissolution time and/or
thickness, thus pre-staging in fractions the release of the overall
burden and reducing the rate of uptake to less than that toxic.
Magnetizable spring stainless steel particulate is not absorbed but
remains after the absorbable matrix or base has disappeared;
innocuous, no further treatment to remove the residue is needed.
Whether applied by dipping, spraying, sputtering, vapor deposition,
plating, or a combination of these, magnetic lanthanoid residue is
toxic and encapsulated within a chemically inert and isolating
nonabsorbable polymeric or metallic coating, usually of gold.
Neodymium iron boron lanthanoid particulate, for example, allows
replacing a much larger mass of an alternative material, but like
those materials, must be nonabsorbably and biocompatibly
encapsulated.
[1967] In an absorbable quasi-intrinsically magnetized stent-jacket
or absorbable shield, the absorbable substance of the matrix is a
glycolic acid-based copolymer, such as polylactic-coglycolic acid
with the glycolide content increased as the brevity of intact life
or persistence desired, and the resilience determined by the
intrinsic properties of the copolymer, thickness of the layer or
layers, the number and size of perforation, and whether the jacket
is indented or fissured to create a hinging line of flexion.
Whether disintegrated spontaneously or on demand as addressed in
the section to follow, a temporary stent-jacket is not
intrinsically magnetizable as are certain stainless steels and must
be magnetized by adding bar magnets. These can consist of tiny
magnets embedded within a matrix as in quasi-intrinsically
magnetized permanent and destructible on demand stent-jackets or
magnets mounted about the outer surface of the jacket.
[1968] As strongly magnetizable material is not absorbable, these
are left behind after the matrix or base-tube disintegrates.
However, neodymium iron boron lanthanoid magnets, with rounded
corners if larger, encapsulated in gold are so small that
irritation to neighboring tissue should seldom not arise. If it
does, then the magnets are resituated or extracted by the
stereotactic means addressed above in section entitled 4g Emergency
Recovery ofMiniballs and Stays and below in section X2c entitled
Stereotactic Arrest and Extraction of a Dangerously Circulatinh,
Mispositioned, or Embolizing Miniball. Encapsulation in gold plate,
for example, is treated for surface contaminants and rid of surface
defects such as microfractures and voids, if any, by means
addressed in the section below entitled Miniature Ball
Implants.
[1969] Encapsulated for chemical isolation, unless removed, the
magnets may preclude the postimplantation use of magnetic resonance
imaging; however, these need not be retrieved to accommodate more
recent pacemaker or cardioverter resynchronization implants. The
decision to use a permanent or absorbable jacket depends upon the
prospects for the subsidence of occlusive proliferation and/or the
recovery of wall strength. Inasmuch as the reduction or shrinking
that usually follows treatment of an aneurysm is not associated
with an eventual recovery of wall strength that would justify the
explantation (removal) of an enlargement restraining jacket, a
jacket to contain an incipient aneurysm, for example, should be
nonabsorbable.
[1970] The same pertains to a stent-jacket used to restrain a
collapsed trachea in veterinary practice, which will likewise
remain weak. A magnetless side-slit polymeric base-tube affords
greater strength, uniformity of inward restraint over the encircled
segment than can an alternative wrap (bandage), and does so without
concession to compliance with the pulse. In an abdominal aortic
aneurysm where the surrounding clearance is adequate, for example,
the jacket is secured with side-straps; otherwise, end-ties as
addressed above in the section entitled Jacket End-ties and
Side-straps are used.
[1971] I10b. Noninvasive Dissolution on Demand of Absorbable
Stent-Jackets, Base-Tubes, Radiation Shields, and Miniballs
[1972] A miniball may require to be eliminated for a number of
reasons, some with the miniball positioned close to others, or
because it has entered the bloodstream. This section will address
both eventualities. The preceding section entitled Absorbable
Extraluminal Magnetic Stent-jackets and Materials specified
numerous absorbable materials suitable for use in an extraluminal
stent. Situated outside the lumen, an extraluminal absorbable stent
encircling a vessel is not constantly washed over by blood to
accelerate its breakdown by hydrolytic and enzymatic action as
would an endoluminal stent of like formulation. Moreover, unlike an
endoluminal stent, which to exert the radially outward force
necessary to prevent migration must be substantially noncompliant,
the materials in an extraluminal stent must comply with the
expansion and contraction of the ductus.
[1973] The required combination of elasticity, resilience, and
absorbability to do this without leaving a toxic residue or
revealing inadequate fatigue endurance eliminates most materials,
to include magnesium and its alloys, for example. Materials that
are absorbable on demand are absorbable materials which have been
modified or supplemented to allow their immediate dissolution prior
to reaching the normal term for spontaneous dissolution or which
have been modified to extend the period for spontaneous dissolution
as well as allow their immediate dissolution prior to reaching the
extended term for spontaneous dissolution. One approach to varying
the spontaneous interval preceding disintegration, addressed in the
last section above, is a jacket or matrix formulation of glycolic
acid-based copolymer, such as polylactic-coglycolic acid, with the
glycolide content increased as the brevity of intact life or
persistence desired.
[1974] A term exceeding that of a suitable absorbable material is
then obtained by incorporating an agent of dissolution within a
material that would otherwise be nonabsorbable. When not deeply
implanted, the rate of dissolution of the material, whether
absorbable or nonabsorbable, can be accelerated by direct heating
over one or more intervals where the temperature is kept well below
most actual melting points, which would injure tissue. For implants
positioned more deeply as does not allow the direct application of
heat, the implant is modified to remotely radiate heat from within
by induction when the patient is placed in a radiofrequency
alternating magnetic or electromagnetic field. This will induce
heat in any ferrous object within the field, which will be limited
in the extent to which it can be focused to select only one of a
number of like miniballs, for example, for disintegration.
[1975] Where the need to disintegrate one of a number of otherwise
similar implants is more likely, that implant is formulated to
disintegrate at a lower temperature by means such as addressed
below in this section. A miniball that is disintegrable on demand
without significant insoluble or toxic residue affords the option
of eliminating it from an accidental embolizing situation without
the need for an impasse-jacket, as addressed below in the section
entitled Miniball and Ferrofluid-impassable Jackets, or
Impasse-jackets. Such modification consists of incorporating iron
having sufficient continuity to support the induction of the eddy
currents necessary to generate the temperature required. When the
rate of dissolution responsive to a safe amount of heat alone is
too low, the heat is used to first melt a biocompatible solvent
which has been mixed into the matrix or jacket material in
dispersed beads, or laminated with the matrix or jacket.
[1976] Using such means, provided both the material and solvent are
biocompatible, nominally nonabsorbable materials can be rendered
effectively absorbable. The most common example water for
dissolving homopolymers and copolymers of polylactic and
polyglycolic acid, a solvent liquid at room temperature must be
kept separate until dissolution is initiated. A gel that releases
water when heated or a biocompatible coating of a material with a
lower melting point than the material of the matrix or jacket is
used to contain the solvent. The solvent, here water, can also be
released from dispersed beads by containment within a capsule or
casing material of lower melting point than the solvent it
contains. With water as a liquid solvent, encapsulation is within
silicone wax with a melting point of 127 degrees.
[1977] The rate of absorption of an absorbable component, whether
an extraluminal stent or a radiation shield needed only
temporarily, for example, can be increased by chemically altering
the polymer, and the absolute time required to effect dissolution,
by introducing or increasing the number and area of perforations or
increasing the thickness. Adjustments in chemistry, composition,
and/or dimensions that affect resilience must be counterbalanced or
offset to preserve compliance to the ductus motility or compensated
for by the impressing of an indenting line (fissure, furrow, flex
line, hinging line) or lines for increased flexion. For a given
material, thickness, and proportion of perforations, the primary
determinant of dissolution rate is the extent and type of tissue
contact; in a body cavity, contact may be negligible compared to
the relative lack of space surrounding a peripheral artery, for
example.
[1978] The surface activity or metabolic rate of tissue is greater
within tissue, such as the parenchyma or medulla of the organ than
outside where a stent-jacket or absorbable patch-magnet, for
example, would most often be placed. The longer rate of dissolution
of a given absorbable material when contact with active tissue is
less prompts the application of a method for inducing dissolution
from outside the body on demand. Unlike the dissolution of an
expansion insert, the dissolution of an absorbable stent-jacket or
any other implant described herein is not incremental by virtue of
addressing different layers used for this purpose but is absolute,
to be effected at once.
[1979] Accordingly, whether the material is inherently absorbable
or is nonabsorbable but adapted as indicated, when radiological
examination reveals that the material has not degraded, it is
actively disintegrated. If the jacket or matrix is made of a
polylactic coglycolic acid, for example, it can be seeded for the
noninvasive discretionary dissolution on demand with small pockets
of bound or encapsulated water released when heated. The rate of
dissolution is further accelerated when the solvent or enzyme is
contained within a laminated layer and further accelerated still
when the jacket or matrix is enclosed within an outer jacket
containing the solvent or enzyme. The same method can be applied to
numerous alternative materials where dissolution is effected
through the discretionary timed release of a solvent or enzyme, for
example.
[1980] One way to do this is to include a hydrogel along with
ferromagnetic, medicinal, shielding, and/or any other particulates
in a polylactic-coglycolic acid absorbable polymer matrix while in
the amorphous or semimolten phase for extrusion. The
hypoimmunologically processed gelatin-based hydrojel, for example,
will retain its bound water when passed through the extruder. Using
the hydrogel can provide the additional benefit that the material
itself is absorbable. When the absorbable base-tube or radiation
shield in which the water or other solvent binding gel is
incorporated is later heated to its melting point below that of the
surrounding matrix, the jel will release the solvent, which can
include an enzyme, drug, or other therapeutic substance not
destroyed during warming and extrusion.
[1981] Using this method, dissolution on demand is noninvasive
whether the implant is placed shallow enough to heat directly with
a hand dryer or placed more deeply, necessitaties the inclusion of
heat inductible matter and placing the patient in a radiofrequency
alternating magnetic field. Invasively effecting dissolution by
direct wetting with water, enzyme, or a chemical solvent is
substantially limited to application in an open surgical field. The
polymer matrix and/or the gel can incorporate medication released
as the matrix is dissolved, and the water bound in the gel can
include glycolytic enzymes and lactase, which will act to break
down the polylactic coglycolic matrix, for example, but not the
hydrogel. Biodegradable anhydrides have long been used to release
drugs and bioactive substances incorporated within the polymer by
entrapment or encapsulation.
[1982] Dissolution on demand applied to radiation shields,
addressed in the section above entitled Radiation Shield-jackets
and Radiation Shielded Stent-jackets Absorbable and Nonabsorbable,
pertains to the matrix; if toxic, the particulate is encapsulated
for chemical isolation. Formulating the solvent and or its outer
coating in each implant, such as a miniball, to flow at a different
temperature and/or incorporating different amounts of ferrous
matter in each will allow the differential selection of all those
that disintegrate at and below a certain temperature but will not
select among these. The incorporation within a tiny miniball, for
example, of a tuned circuit (Niwa, T., Takemura, Y., Inoue, T.,
Aida, N., Kurihara, H., and Hisa, T. 2008. "Implant Hyperthermia
Resonant Circuit Produces Heat in Response to MRI Unit
Radiofrequency Pulses," British Journal of Radiology 81(961):69-72,
available at http://bjr.birjournals.org/cgi/content/full/81/961/69)
faces the problems of inadequate space and incomplete
absorbability.
[1983] For selectively destroying a miniball close to others, the
tapered probe at the end of a powerful electromagnet with its
polarity reversed at a radiofrequency will induce heat in any
object containing ferrous material of sufficient continuity but,
even though these are marked with bright contrast, may not be
aimable with sufficient accuracy to assure the selectability of one
miniball, for example, amid or proximate to others for
disintegration. Provided a miniball incorporates ferrous content
and means for its disintegration on demand by heat induction, an
electromagnet energized with current continuously alternated at
high frequency preprocedurally positioned downstream can
disintegrate a miniball which escapes into the bloodstream
regardless of its exact location, as addressed below in the section
entitled Downstream Disintegration of a Circulating Miniball.
[1984] I10c. Absorbable and Nonabsorbable Circumvascular Jackets
with Medicated Linings
[1985] Atherosclerosis appearing at least in part adventitial in
origin, as addressed above in the section entitled Accommodation of
the Adventitial Vasculature, Innervation, and Perivascular Fat and
below in this section, a moisture barrier-coated viscoelastic
polyurethane foam lining can be wetted with a medicinal or
bioactive liquid or facially impregnated with a cream or gel with
negligible effect on its mechanical properties. While it would
succeed in targeting a particular segment along the outer or
adventitial surface of the ductus, the use of a magnetless
nonabsorbable jacket is not preferred as requiring percutaneous
access first to implant and then to recover or explant the jacket;
single femoral, brachial, or cubital (radial) entry with
transluminal placement of medication mniballs is preferred as less
invasive.
[1986] When access is not difficult, a fully absorbable magnetless
or nonmagnetic stent-jacket with the elasticity to comply with the
autonomic action of the ductus or stays that consist exclusively of
medication and are completely absorbed also eliminate the need for
reentry at a later date. An absorbable stent-jacket with medicated
lining and sufficiently susceptible medication miniballs or stays
will release medication adventitially without and within, if
indicated, under compressive force determined by the strength of
jacket magnetization. The drugs used with absorbable jackets and
absorbable medication stays would typically include or consist of
statins, steroids, and antibiotics.
[1987] Fully absorbable jackets can be used with absorbable or
nonabsorbable ferromagnetic miniballs. More aggressive treatment of
a segment is simultaneously endoluminal as well as circumvascular
through the use a holding impasse-jacket, as addressed above in the
section entitled Concept of the Impasse-jacket and in the section
to follow entitled below entitled Miniball and
Ferrojluid-impassable Jackets, or Impasse-jackets. More powerfully
magnetized stent-jackets, impasse-jackets, miniballs, and stays can
be used in any combination to further attract drug carrier
nanoparticles into the lesion. Where the localized circumvascular
release of medication would be therapeutic, the use of an
absorbable stent-jacket with a medicated lining may be
indicated.
[1988] The progressively emerging implication of the adventitia in
atherosclerosis and the adverse sequelae associated with its
treatment make this probable (see, for example, Xu, X., Lin, H.,
Lv, H., Zhang, M., and Zhang, Y. 2007. "Adventitial Lymphatic
Vessels--An Important Role in Atherosclerosis," Medical Hypotheses
69(6):1238-1241; Stern, N. and Marcus, Y. 2006. "Perivascular Fat:
Innocent Bystander or Active Player in Vascular Disease?," Journal
of the Cardiometabolic Syndrome 1(2):115-120; Plekhanova, O. S.,
Stepanova, V. V., Ratner, E. I., Bobik, A., Tkachuk, V. A., and
Parfyonova, Y. V. 2006. "Urokinase Plasminogen Activator in Injured
Adventitia Increases the Number of Myofibroblasts and Augments
Early Proliferation," Journal of Vascular Research 43(5):437-446).
Wilcox, J. N., Okamoto, E. I., Nakahara, K. I., and
Vinten-Johansen, J. 2001. "Perivascular Responses after Angioplasty
which May Contribute to Postangioplasty Restenosis: A Role for
Circulating Myofibroblast Precursors?," Annals of the New York
Academy of Sciences 947:68-92; Wilcox, J. N. and Scott, N. A. 1996.
"Potential Role of the Adventitia in Arteritis and
Atherosclerosis," International Journal of Cardiology 54
Supplement: S21-35).
[1989] Pathology that results from balloon overinflation injury
should not pertain to the angioplasty apparatus described herein
(see, for example, Wallner, K., Sharifi, B. G., Shah, P. K.,
Noguchi, S., DeLeon, H., and Wilcox, J. N. 2001. "Adventitial
Remodeling After Angioplasty is Associated with Expression of
Tenascin mRNA by Adventitial Myofibroblasts," Journal of the
American College of Cardiology 37(2):655-661). The foregoing means,
to include the use of stent-jackets with a medication-coated or
impregnated lining and holding impasse-jackets, allow medication to
be delivered to the targeted segment in far higher concentration
than might be allowed to circulate.
[1990] Where therapeutic doses of a glucocorticosteroid to treat
inflammation associated with a ductus, as in a regional enteritis,
produces side effects of a severity that justifies placing a
holding impasse-jacket or jackets, treatment as addressed in the
section below entitled Chemical Control over Implants and Coated
Implants, to Include Miniballs, Stays, and Prongs allows the
systemic circulation, hence, the side effects, to be avoided.
Acutely affected segments in systemic disorders such as
panarteritis (polyarteritis nodosa, periarteritis nodosa,
Kussmaul's disease, necrotizing arteritis), segmental arterial
mediolysis, Churg-Straus disease, and microscopic polyangiitis, for
example, can thus be provided with the focused delivery of
corticosteroids, usually prednisone or prednisolone, in addition to
the systemic medication essential to treatment, which can therefore
be reduced, averting the onset of hypertension, for example.
[1991] Smaller doses can be time released. The use of strongly
magnetized stent- and holding jackets allows the drug or drugs to
be replenished through the periodic infusion or direct vascular
injection of drug carrier nanoparticles. Given that bacteria such
as Chlamydia pneumoniae may play a role in arteritis and
atherosclerosis (see, for example, Hu, C. L., Xiang, J. Z., Hu, F.
F., and Huang, C. X. 2007. "Adventitial Inflammation: A Possible
Pathogenic Link to the Instability of Atherosclerotic Plaque,"
Medical Hypotheses 68(6):1262-1264.), the medication targeted with
a concurrent background of reduced system dose when possible can
include or consist of antibiotics.
[1992] Perforations for avoiding complete enclosure that would
obstruct gas and other chemical exchange at the outer surface of
the vessel are included in the sections below on various
circumvascular jackets. When the adventitia is diseased or injured,
the stent-jacket can be placed prior to discharge or stays
consisting of medication implanted. Absorbable stent-jackets can be
continuously extruded and sliced or formed by transfer molding of
materials specified under the section below entitled Stent-jacket
expansion insert materials having relatively short breakdown
times.
[1993] I11. Stent-Jacket Expansion Inserts
[1994] I11a. Expansion Inserts Absorbable, Meltable, and
Comminutable for Time-Discrete Decremental Contraction of
Stent-Jackets
[1995] Saliently, the entire subject of size adaptability with no
loss in compliance with expansion and contraction of the ductus is
nonexistent with endoluminal stents. The insertion of an oversized
absorbable endoluminal stent in a dilatated (extatic, distended)
lumen is temporary. An expansion insert is intended to allow a
stent- or impasse-jacketed ductus that is temporarily swollen or
distended by disease to better accommodate the ductus by
contracting in pace with the reduction in swelling, whereupon the
stent-jacket remains as the extravascular component of the stent.
The object in temporarily expanding the stent-jacket is to allow
the placement of a stent-jacket that will continuously accommodate
a substrate ductus which, any anti-inflammatory medication
notwithstanding, will subside (resolve, detumesce, recede, regress)
from an initially swollen condition over an extended period.
[1996] Following treatment, vessels swollen by disease,
implantation, as the result of reperfusion, or incipiently
aneurysmal should gradually revert to substantially normal
dimensions. Elastic and lined with viscoelastic foam, stent-jackets
adjust to reductions in ductus cross-sectional area or caliber over
a limited range. This intrinsic latitude combined with
physiological compliance throughout the period of subsidence is a
significant advantage of an extraluminal over an endoluminal stent.
Use of a somewhat oversized stent-jacket with thicker lining
extends this spontaneous adaptability as well as allows for future
growth in a child, but only up to a point. Beyond that point, to
provide a self-contracting stent that will eliminate the need for a
second procedure to place a smaller jacket requires the use of an
expansion insert.
[1997] Contraction of the stent-jacket base-tube is due to the
gradual dissolusion and loss in compressive strength of the
absorbable insert segment materials used. Ideally, dissolution
proceeds without reintervention, and any need for reintervention is
minimized as to degree of invasiveness. The swelling may be the
result of the pathology treated, a tumefacient used to expand the
lumen wall for implantation, as addressed above in the section
entitled Ductus Wall Tumefacients, or implantation. Whether the
substrate ductus or a segment thereof is enlarged due to
inflammation resulting from chronic disease, injury associated with
angioplasty, the direct result of injury associated with ballistic
implantation, or some combination of these, a stent-jacket with
expansion insert is devised to contract in step with subsidence in
the temporary swelling.
[1998] A similar need for contraction over time may ensue when
antiangiogenic medication, radiation, or ionizing
radiopharmaceuticals in the form of irradiating miniballs and/or
the stent-jacket lining, for example, are used to destroy
neoplastic tissue that extends into the lumen. Materials to shrink
in step with the subsidence in swelling of a ductus while
maintaining consistent mechanical properties whether spontaneously
or in response to heating remain to be developed. In this
circumstance, an expansion insert effectively renders the
stent-jacket self-contracting. Due to the resilience required of a
stent-jacket, the ability to encircle a swollen ductus with a
stent-jacket sized for the normal gauge without circumferential
pressure points is limited and necessitates strong bonding of the
expansion insert.
[1999] Layered (sectional, segmented) expansion inserts such as
those shown FIGS. 8 and 9 can consist, for example, of but a single
polyester such as polylactic acid interleaved with hydrogel
water-releasing segments, bisected at either end or at the midline,
and fastened to the free edges of the side-slit with absorbable
ethyl 2-cyanoacrylate cement. Due to the doubling of free ends,
midsectioning a bilaterally symmetrical succession of segments
yields an acceleration in the rate of dissolution for each like
pair of segments, whereas perforating only specified segments
accelerates the rate for that segment alone. Incorporation of
magnetically susceptible matter into a unitary (monolithic,
nonsectional) expansion insert to allow dissolution to be
accelerated is seldom advisable.
[2000] This is because the radio frequency alternating magnetic
field used to effect heat induction will similarly affect other
elements such as temporary stent-jackets, miniballs, and stays
nonselectively (nonaddressably, nondiscriminately), the latter
better claiming this option. Ferrous content to expedite arrest and
recovery of a lost part with the aid of an impasse trap-jacket or
external electromagnet, for example, is also better applied to
parts which might enter the bloodstream, would prove more difficult
to locate if dropped, or pose greater risk to remove.
Alternatively, the expansion insert consists of a unitary
succession of bonded segments, each capable of reducing expansion
by a measured increment in a given chemical environment wherein
each segment can be accelerated in rate of dissolution through
bilateral symmetry or by perforation or the inclusion of
magnetically susceptible matter.
[2001] The possible combinations of spontaneously and deliberately
or on-demand disintegrated material types and dimensions are many
and afford wide variability in the rate of dissolution, making it
possible to accommodate conditions of inflammation, edema, or
enlargement due to any cause where these resolve over widely
different intervals. The range of such adaptation limited by
material properties and geometry, expansion inserts where swelling
is more considerable are used with an oversized stent-jacket with
thicker moisture barrier-coated viscoelastic polyurethane foam
lining Stent-jacket expansion inserts, shown in FIGS. 7 thru 9, can
be used with stent-jackets of any type, whether intrinsically,
quasi-intrinsically, or extrinsically magnetized, or segmental, as
shown without insert in FIG. 13. The minimization of complications
demands that the stent-jacket be adaptable in size as well as
dependable in maintaining patency.
[2002] To develop materials that vary gradually in composition from
end to end so that a nonsegmented insert will dissolve along a
gradient would allow nonincremental or continuous shrinkage;
however, the approximation of continuity that can be attained
incrementally serves the need, and the cost to develop such
materials for this limited purpose is unjustified. Disintegration
on demand is obtained through the use of nonabsorbable layers when
the subsidence and expansion period exceeds that obtainable using
absorbable materials, and justifies a second procedure, which is
preferably noninvasive through the application of heat directed
from outside the body when the not deep or by induction in an
alternating field. Nonabsorbable materials such as stone, are
disintegrated noninvasively, while polymers are usually dissolved
through the minimally invasive direct injection of a solvent.
[2003] Stone to absorbable polymer bonds are generally made with
implantable grade cyanoacrylate cement. The need for a followup
procedure of any kind least preferred and one that is invasive less
preferred still, spontaneous dissolution should be used whenever
the term for subsidence falls within the period attainable using
absorbable materials. In a follow-up lithotripsy, unless the
continuity through the depth of the tissue serves to relate the
source of excitation to the insert as target, intracavitary
infusion is necessary for the lithotriptor to pulverize the stone
insert or the final stone segment. Pulsed laser lithotripsy through
a laparoscopic sized entry wound should not be necessary. In most
instances, negligible swelling can be accommodated by increasing
the thickness of the moisture barrier-coated viscoelastic
polyurethane foam lining in a jacket of larger duaneter.
[2004] Upon subsidence, the ductus may then expand and contract
within the thickness of the foam without opening and closing the
side-slit or slot. Intermittent separation at the adventitial-foam
interface due to slower conformation recovery is is probably
innocuous if not beneficial. The use of an oversized jacket with
thicker foam lining is thus an additional measure if not an
alternative to the use of an expansion insert. Were the thickness
of the foam increased to the point where the strength of
magnetization would have to be increased to offset the increase in
the radial distance, then upon shrinking of the ductus with
compression of the foam, the field strength could result in
pull-through or delamination.
[2005] Since the mechanical properties of the ductus will change
during healing as to defy prediction, the magnetic strength should
be kept to little more than clinical judgment if not the actual
testing of nearby like tissue shows can be withstood. While not
shown in FIG. 9, the material or materials of the expansion insert
must allow for an arcuate or bowed form to encircle without
tangentially encroaching upon, pressing into, and irritating the
swollen ductus. Bursting of a monolithic insert, or the bonds
between the segments of a multisegment insert under the restorative
force of the stent-jacket and autonomic function of the ductus is
compensated for by increasing the bonding surface as shown in FIG.
8 and if necessary, the use of stronger materials. Before adjusting
the formulation or the dimensions of the materials, which may alter
the absorption time, different bonding surface angles are tested
for bonding strength.
[2006] Whether pending or following subsidence, an out of round
condition diametrically from the slit or slot or approaching and
alongside the stent-jacket side-slit or side-slot can usually be
disregarded. When felt preferable to more evenly distribute the
forces, voids are accommodated by proportionally increasing the
moisture barrier-coated viscoelastic polyurethane foam lining in
thickness. Foam linings are addressed above in the sections
entitled Requirement for Stent- and Shield-jacket Moisture
barrier-coated viscoelastic polyurethane foam Lining and Stent- and
Shield-jacket Moisture barrier-coated viscoelastic polyurethane
foam Linings. Upon subsidence, this small added thickness of foam
is readily compressed so that the jacket can return to a round
cross section. Stent- and shield-jackets are packaged with
expansion insert segments, or strips of various materials in
different dimensions to be bonded side to side with cyanoacrylate
cement for speed, and strips of moisture barrier-coated
viscoelastic polyurethane foam to take up the out of round
circumference toward the insert slit or slot.
[2007] Situated outside the bloodstream, the rate at which
absorbable layers in an expansion insert disintegrate is slower
than were the same material placed constantly washed over by the
blood. When necessary, this is compensated for by incorporating
constituents in the layer that will accelerate its dissolution when
heated. Expansion inserts may be slit at the center, slit to one
side, or exceptionally, glued shut after placement, pending initial
absorption to produce free edges. Heating and the injection of a
solvent, for example, change a layer or segment of the insert that
would have been spontaneously or passively dissipated to one of
controlled removal. When the insert material is absorbable,
controlled removal induces absorption earlier in response to a
radiological finding of early subsidence. When not absorbable,
controlled removal is by means of comminution, as addressed below
in the section that follows.
[2008] So that the operator or a technician can tailor a
stent-jacket to the actual conditions encountered, as well as to
reduce costs, stent-jackets are standardized based upon gauge.
Since the spines in a spine and ribs type stent-jacket must expand
and contract independently, an expansion insert for such a
stent-jacket must be sectioned, or divided longitudinally, by
independent bonding to each rib. As with the option to insert
straight-line or double-wedge linings, expansion inserts are sold
apart from the base stent-jacket. To allow the lining insert to
extend to the edges of the side-slit or side-slot, the expansion
insert is bonded along the facing edges of the slit or slot, the
strength of bonding increased by lapping over and gluing the inset
onto the outer surface of the stent-jacket alongside the slit or
slot to the distance necessary.
[2009] A shield-jacket placed to allow warming by magnetic or
electromagnetic heat induction postprocedurally is seldom temporary
but rather a long-term if not permanent end-implant, for which the
addition of an expansion insert may be appropriate. A shield-jacket
used as a temporary implant, that is, used to prevent a perforation
from striking neighboring tissue during discharge and removed prior
to closing is sized for the gauge needed when used. When swelling
is minor and expected to resolve quickly after a reasonably
predictable interval, the expansion insert is relatively narrow,
absorbable, usually a single layer or monolithic piece of an
absorbable suture or tissue engineering scaffold material such as
polyglycolic acid glued to the base-tube or the intrinsically or
quasi-intrinsically magnetized stent-jacket.
[2010] When the term pending subsidence or resolution is brief, the
expansion insert is usually bonded along one opposing edge of the
side-slit or side-slot. Whether the slit in the insert is
longitudinally centered or situated to one side, the segments or
layers of the insert must dissipate in the order of removal from
the slit. Since a center-slit allows layers of the same material to
either side rather than a layer of double the width or thickness to
one side, each successive layer can be halved, for example, in
width or thickness with double the bonded edges. For this reason a
center-slit generally provides greater dependability. When the
insert slit is in the longitudinal center, the materials to either
of its sides may be the same or different but must dissipate in the
order of proximity to the respective free edge of the jacket
slit.
[2011] By the same token, the materials and thicknesses of the
expansion layers or segments to either side need not be the same,
or bilaterally symmetrical. When swelling is more pronounced, the
wider expansion insert required calls for the increased
dependability of a center slit insert. When subsidence is
anticipated to be in stages or incremental, the width of the layers
is keyed to the anticipated duration of the stages. When the
interval for subsidence is overall brief, the insert will usually
be made to open along one edge. Longer intervals that call for
wider layers are better divided to either side of a center-slit.
When swelling is considerable, a wide insert such as shown in FIGS.
8 and 9 is center-slit, that is, made to open along the
longitudinal center, receding laterally from which are
progressively less quickly absorbed layers, usually polymeric.
[2012] When the overall time for subsidence is unpredictable or the
prediction undependable, the layers for later stages of
dissolution, which consecutively more approximate the free edges of
the stent-jacket to one or both sides in the order of increasing
durability or duration, are made for dissolution on demand. Such
materials may be accelerated in breakdown time or initiated in
breakdown by exposure to heat or an injectant. For dissolution on
demand only, that is, where the interval for expansion cannot be
predicted but will likely take a long time, the layers need not be
absorbable at all but rather made of stone that allows
discretionary removal by the clinician with the aid of a
lithotriptor. Layer bonding agents are addressed below in this
section. Since the absorbable components addressed herein are not
embedded within tissue but rather positioned outside the ductus,
exposure to serous fluid is present, but exposure to enzymes that
would effect dissolution is not.
[2013] For this reason, another approach to dissolution on demand
is the incorporation by embedment into the matrix of the expansion
insert material of a solvent respective of the insert layer, which
is liberated by remote heat induction. Such means are delineated
above in the section entitled Noninvasive Dissolution on Demand of
Absorbable Stent-jackets and Base-tubes, among others, and applies
no less to the matrix of any absorbable component described herein,
whether an expansion insert, layer thereof, stent-jacket, or
radiation shield, for example. To allow the stent-jacket to expand
and contract with the involuntary movement in the ductus throughout
the period of subsidence, when the other side is to open, the
expansion insert is placed inside and glued to the base-tube along
one opposing edge of the side-slit or side-slot. When the center is
to open, it is glued at both opposing edges.
[2014] Most expansion inserts are homogeneous, consisting of an
absorbable material such as polylactic coglycolic polymer for
dissolution over a certain relatively brief interval. When
contraction is to be incremental over an extended period, the
layers are bonded side to side in order of dissolution beginning
with that first to disperse at the unglued end or ends. Spontaneous
dissolution is only controllable to the extent that the layer or
segment thickness affects the dissolution time, and the material
can be modified to increase this interval. This assumes that the
gap is large enough for the material to maintain parity with the
rate of subsidence. Greater control is attained with materials
having a longer dissolution time where dissolution can be
accelerated by applying heat, a solvent, or some combination of
these, for example.
[2015] In situations where subsidence cannot be predicted to occur
within the interval for spontaneous dissolution of a material, a
permanent material that can be disintegrated on demand is used
where the material is susceptible to dissolution in reaction to a
safe dissolvent or lithotriptor induced fragmentation. In addition
to providing contraction that is spontaneous over a reasonably
predeterminable interval, or controllable responsive to action by
the operator, the materials can be combined for early spontaneity
and later contol. Materials rendered absorbable when warmed, for
example, such as by a heat-window or windows in the muzzle-head of
a minimally or fully ablation or angioplasty-capable
barrel-assembly, are used for discretionary reduction in diameter
contingent upon the confirmation of subsidence by imaging.
[2016] Stony materials provide expansion in diameter that will
persist until such layers are disintegrated by lithotripsy
(extracorporeal litholapaxy, ultrasonic lithotresis, mechanical
litholysis, or lithodialysis) during a follow-up procedure. The
dissolution of stony layers in an expansion insert can also be
effected chemically. For this purpose, a solvent such as potassium
citrate (see, for example, Frang, D. 1978. "A Comparative Study of
Three Different Citrate Combinations of Litholytic Action,"
International Urology and Nephrology 10(3):195-199) or sodium
bicarbonate is applied directly by injection under fluoroscopic
observation rather than systemically over time. Quick dissolution
for response to specified agents may necessitate synthetic stone
specially formulated for the purpose.
[2017] The stent-jacket surrounding the ductus so that endoluminal
access would necessate perforating the lumen wall, a litholytic
solution can be injected locally from outside the body.
Exceptionally, where the transluminal placement of a conventional
(endoluminal) absorbable stent to temporarily support an enlarged
or collapsed ductus pending subsidence is impossible and entry by
means of an angiotomy would result in greater trauma, completely
absorbable stays used without a circumvascular stent-jacket, as
will be described, may be preferred. Any instance of absorption can
include the release of medication. The stent-jacket with expansion
insert consisting of one or several expansion strips and
eccentricity gap filling strips of moisture barrier-coated
viscoelastic polyurethane foam can be prepared before the
procedure, or, if the duration and rate and/or caliber required is
not certain until entry, midprocedurally.
[2018] When the ductus is expected to recover to a normal condition
with slight reduction in gauge following the temporary need for
stenting, the extraluminal stent is devised to disintegrate over
the period allowed for subsidence. Magnetic stents of the latter
type are addressed above in the section entitled Absorbable
Magnetic Stent-jackets with the miniballs used addressed Temporary
(Absorbable) Ferromagnetic Miniballs and Other Implants. When
continued stenting is needed and the reduction in gauge is slight,
the foam lining in a permanent stent will accommodate the reduction
in gauge. Expansion inserts can be made to disintegrate using heat,
extracorporeal shock wave lithotripsy, or percutaneous (endoscopic)
intracorporeal lithotripsy whether ultrasonic, electrohydraulic,
laser, or pneumatic mechanical.
[2019] Intracorporeal (invasive) lithotripsy should be reserved for
only those instances that do not respond to extracorporeal
(noninvasive) lithotripsy where contraction of the stent-jacket is
judged sufficiently important to justify it. Stone that can be
prepared with a suitable chemical composition for safe dissolution
with a solvent can be removed by injection, by release of the
solvent from within the stent when heated from outside the body, or
when heat induced in the stent when placed in a radio frequency
alternating magnetic field. An extraluminal stent placed in
childhood remain functional for many years.
[2020] Eventual failure will most likely result from a loss of
base-tube resiliency, pull-through or delamination after much time
less likely due to trajectory closure, tissue infiltration, and
mechanosensory function (see, for example, Chiquet, M., Gelman, L.,
Lutz, R., and Maier, S. 2009. "From Mechanotransduction to
Extracellular Matrix Gene Expression in Fibroblasts," Biochimica et
Biophysica Acta 1793(5):911-920; Von Offenberg Sweeney, N.,
Cummins, P. M., Cotter, E. J., Fitzpatrick, P. A., Birney, Y. A.,
Redmond, E. M., and Cahill, P. A. 2005. "Cyclic Strain-mediated
Regulation of Vascular Endothelial Cell Migration and Tube
Formation," Biochemical and Biophysical Research Communications
329(2):573-582; Sarasa-Renedo, A. and Chiquet, M. 2005. "Mechanical
Signals Regulating Extracellular Matrix Gene Expression in
Fibroblasts," Scandinavian Journal of Medical Science in Sports
15(4):223-230; Shukla, A., Dunn, A. R., Moses, M. A., and Van
Vliet, K. J. 2004. "Endothelial Cells as Mechanical Transducers:
Enzymatic Activity and Network Formation under Cyclic Strain,"
Mechanics and Chemistry of Biosystems 1(4):279-290; Silver, F. H.
and Siperko, L. M. 2003. "Mechanosensing and Mechanochemical
Transduction: How is Mechanical Energy Sensed and Converted into
Chemical Energy in an Extracellular Matrix?," Critical Reviews in
Biomedical Engineering 31(4):255-331).
[2021] In addition to relatively short-term expansion inserts that
allow for the initial resolution of swelling, expansion inserts can
incorporate materials to be disintegrated by deliberate action.
Expansion insert or insert layer materials to persist until
intentionally removed on the basis of radiological findings
generally consist of stone for destruction by lithotripsy. To
prevent other components of the stent-jacket from being shocked or
jarred possibly causing delamination of the adventitia or media and
therewith patenting failure, the material or layers of the
expansion insert are formulated or selected for greater
susceptibility to disintegration. With or without loss of function,
nonabsorbable stent-jackets that remain past the need for patenting
can usually be left in place.
[2022] A loss in base-tube resilience, pull-through, or
delamination do not predispose to the entry of miniballs into the
circulation; the adaxial lamina will have long since healed behind
the abaxial miniballs. However, where stone layers for removal by
lithotripsy have been included, wide stays are used instead, or
discounting the use of stays, an impasse-jacket is placed
downstream from the miniballs at the same time that the
stent-jacket is placed. Materials for destruction on demand are
addressed below in the section entitled Lithotriptor-destructible
Stone Stent-jacket Expansion inserts and Differentially
Destructible Expansion insert Layers. For differential and
therefore selectable destructability, harder or stony materials
must exhibit a marked frangibility at the frequency of the pulses
and level of power used.
[2023] Stent-jackets for use with an expansion insert that will
undergo lithotripsy should be intrinsically or quasi-intrinsically
magnetized, or if extrinsically magnetized, then should use magnets
that are not susceptible to damage due to lithotripsy. A
stent-jacket with stony layer should be oriented with the side-slit
placed to expedite lithotripsy. When the positioning of a side-slot
must conform to a prior requirement, such as to straddle a
frenulum, this will not be possible, nor will rotating the jacket
about the ductus with the aid of an external electromagnet. If
readily accessible through a small incision, the expansion insert
is removed manually by direct access. It will not be possible to
rotate the stent-jacket about the substrate ductus by means of
exerting tractive force on its discrete magnets with an external
electromagnet. Base-tube expandability is limited by the increase
in resistance to further expansion and in distortion from
round.
[2024] The percent expansion is limited not only by the fact that
the stent-jacket must sufficiently conform to the ductus once
subsided but by the fact that magnetization must not be extended to
the insert. Since the insert resists the restorative force of the
base-tube, the capacity of the base-tube for further expansion in
compliance with muscle action in the ductus in its swollen
condition is reduced; that is, the use of an expansion insert
partially uses and deducts from the overall expandability of the
base-tube. This can be compensated for through the use of a larger
diameter base-tube with thicker foam lining within the range of
thickness that does not require an increase in strength of
magnetization as could result in pull-through or delamination. In
some instances, a larger jacket can be used alone.
[2025] Expansion inserts are bisected lengthwise as extend the
base-tube in circumference while providing a side-slit or
side-slot. As shown in FIG. 7, to allow the stent-jacket insertion
tool (addressed below) to be slid along the edges upon insertion
and avoid any inward protrusions as would irritate the ductus, the
expansion insertion is bonded along the free edges of the side-slit
or side-slot and lapped over onto the outer surface to provide a
larger bonding surface. The free edges in any practical
stent-jacket or any other implant described herein are always
rounded. Any cut-outs in the stent-jacket that would be needed to
clear anatomical side branches of the target ductus should be
positioned away from the insert to avoid weakening it. Initial
enlargement in a ductus can result from coexisting (comorbid,
compounded, overlapping) conditions of which the period for the
subsidence of each is separate in time so that the ductus recedes
in steps.
[2026] Secondary enlargement in gauge of the ductus due to growth
or hyperplasia generally recommends the use of a larger jacket with
thicker foam lining and an expansion insert. When the time for
these successive regressions is reasonably predictable, the object
is to time the contraction of the stent to the reduction schedule
anticipated. The time of dissolution of the adhesive used to bond
each successive layer need not exhibit an absorption time equal to
that of the material of its respective layer. While to make the
base-tube itself of a material that shrinks at a desired average
rate would sustain superior circumvascular circularity during
subsidence, the material would at the same time have to present the
correct combination of resilience or restorative force and shape
memory, permanence, implantability, and dependability as to
diameter when fully contracted to the end diameter.
[2027] The use of a temporary expansion insert based upon an
absorbable material or layers of absorbable materials is indicated
when 1. The condition is familiar as to afford a rate of subsidence
that is substantially predictable, 2. Subsidence will occur over a
relatively short interval, 3. The reduction in size will be
relatively small, and 4. The potential consequences of
miscalculation in timing and gauge are limited to a range that can
be tolerated. Materials vary in degree of absorption time
predictability. The dependability of the time of stent contraction
as the result of dissolution of the expansion insert as a whole or
in stages is increased by incorporating polyester-based materials
that are more predictable than gut as to time of absorption as well
as nonallergenic.
[2028] Similarly, absorbable adhesives used to bond expansion
inserts to the free ends and outer surface of the stent-jacket
side-slit and to bond different segments within the insert when
present are better predictable as to dissolution time as well as
tissue compatibility when consisting of a polyester-based synthetic
such as specified below rather than a natural material, such as
collagen, gelatin-resorcinol pentanedial, or gelatin-resorcinol
ethanedial. The insert is glued along the side-slit or slot on one
side, or if to open at an intervening point, then at both sides,
allowed to cure, and bisected. For a base-tube of given elasticity,
the breadth or reach of the expansion insert across the gap of the
open side-slit will be limited by the need for the side-slit when
expanded by the insertion tool to clear the diameter of the ductus
without risk of the insert breaking loose or fracturing.
[2029] This can be overcome by using a base-tube having a somewhat
larger diameter with a thicker foam lining rather than changing to
a base-tube that lacks perforations believed beneficial for
`breathing,` is thinner, or made of less resilient material. The
primary requirement of the base-tube is that it achieve good
compliance with the smooth muscle function of the ductus without
avoidable irritation or interference. Since for a given material,
base-tube flexibility results from the intrinsic elasticity of the
base-tube material, its thickness, and the shape and area of any
perforations, preserving adequate resilience without going to a
different material or larger base-tube necessitates increasing
base-tube thickness and reducing or eliminating any perforations as
the extent of expansion is increased.
[2030] Whether the insert is absorbable or destructible, inward
protrusion as would protrude into the substrate ductus must be
avoided. When a radial thickness of an insert segment of an
irreplaceable material is needed as would extend radially outward
to irritate neighboring tissue, no more of the segment should
extend inward from the internal surface of the base-tube than can
be accommodated by a separate moisture barrier-coated viscoelastic
polyurethane foam lining. The overlap onto the outer surface of the
base-tube to increase the bonding surface must not be so thick that
it protrudes into neighboring tissue. Nor should it extend onto the
external surface to a distance from the free edge that it displaces
perforations which impart the resilience desired as well as allow
the adventitia to `breath.`
[2031] Also not to be displaced are any extrinsic magnets, which
should remain radially aligned to their respective
ductus-intramural implants during subsidence. The magnetic force
between the intravascular and extravacular components will
compensate for some loss in resilience or shape memory of the
base-tube over time. Depending upon the exposure to the agents of
dissolution, most often water and proteolytic enzymes, absorbable
materials can include dried sugars, syrups, absorbable suture
polymers, and less often, collagen (gut). The persistence of gut is
increased through treatment with aldehyde solution and chromic
salts (chromium trioxide), as is conventional with chromic catgut
suture. As compared to synthetic materials, gut is more tolerant of
variability in the surrounding environment giving it a wider range
of application but less predictable in dissolution time.
[2032] The chemical environment of the expansion insert is,
however, quite different than and more widely variable than that of
suture, which unlike the expansion insert, courses through and
remains in intimate contact with the surrounding tissue over its
entire surface area, which is proportionately large in relation to
its volume. The mechanical factors pertinent to suture also differ
in that the edges of the tissue to be united remain coapted or are
held in apposition despite swelling, and in that tensile strength,
amenability to knotting, and capillarity that would permit entry by
bacteria into the penetrated tissue are important. The expansion
insert segments or layers and any agents for the dissolution of
these to be embedded in them for release by heating, for example,
are selected on the basis of the chemical environment at the
side-slit.
[2033] Heating can be induced in a radio frequency alternating
magnetic field or by using the heat-windows or feeding hot gas
through an ablation or ablation or angioplasty-capable
barrel-assembly. The former is preferable as noninvasive with the
heat induced and radiated within the insert or insert layer, where
the surrounding matrix provides thermal insulation. Yet another
relatively unobtrusive technique is intracavitary (intraperitoneal,
intrapericardial) fluid infusion such as used in ultrasonography
with saline solution, where the fluid (water) contains the solvent
or enzyme for dissolution. Heating if not of such long duration as
to tax the patient can often prove effective to accelerate the
dissolution of aborbable materials without the need for a
heat-released embedded solvent or different solvents in each
layer.
[2034] Water and native enzymes at the site break down their
respective substrate insert or its layers. Unlike most implants,
the stent-jacket is exposed to serous fluid and exudates rather
than the enzymes within tissue. When a uniform exposure of the
different portions of a given insert or its layers to the same
chemical environment cannot be depended upon, compensatory
increases in rate of dissolution can be embedded with encapsulated
solvents that if necessary can be released to effect the
dissolution of that layer. Agents of dissolution for absorbable
layers include water and enzymes. Absorbable layers or segments
with different dissolution times are sequenced in order of the
quickest to dissolve at the free end and that next quick adjacent
to it and closer to the bonded end.
[2035] When imaging reveals that a layer or layers should be
eliminated before the period for spontaneous absorption has
elapsed, a solvent respective of each such layer or segment is
embedded within that layer for liberation by heating. Such
dissolution agents generally consist of water to hydrolyze ester
bond-based polymers and acid hydrolytic and proteolytic
(collagenolytic) enzymes for gut (catgut, collagen);
physiologically exposed polyglycolide is ordinarily broken down by
enzymes that exhibit esterase activity. With either gut or
polymers, a hydrogel may be used for the release of water to
activate chemically constituent or mechanically included (enclosed,
embedded) proteolytic enzymes or to nonenzymatically hydrolyze the
ester bonds of alpha-polyester polymers.
[2036] Provided it has the requisite strength and bonding strength,
a water releasing hydrogel adhesive or layers thereof interleaved
among absorbable layers may be used to bond layers of
water-degraded materials where each such layer moving toward the
surface of the stent-jacket has a progressively longer degradation
time. The adhesive hydrogel may additionally release medication to
accelerate healing and subsidence, for example (see, for example,
Vieira, V. M. P., Hay, L. L., and Smith, D. K. 2017.
"Multi-component Hybrid Hydrogels--Understanding the Extent of
Orthogonal Assembly and Its Impact on Controlled Release," Chemical
Science 8(10):6981-6990; Chivers, P. R. A. and Smith, D. K. 2017.
"Spatially-resolved Soft Materials for Controlled Release--Hybrid
Hydrogels Combining a Robust Photo-activated Polymer Gel with an
Interactive Supramolecular Gel," Chemical Science 8(10):7218-7227;
Kioomars, S., Heidari, S.1, Malaekeh-Nikouei, B., Shayani Rad, M.,
Khameneh, B., and Mohajeri, S. A. 2017. "Ciprofloxacin-imprinted
Hydrogels for Drug Sustained Release in Aqueous Media,"
Pharmaceutical Develeopment and Technology 22(1):122-129; Nakata,
R., Osumi, Y., Miyagawa, S., Tachibana, A., and Tanabe, T. 2015.
"Preparation of Keratin and Chemically Modified Keratin Hydrogels
and Their Evaluation as Cell Substrate with Drug Releasing
Ability," Journal of Bioscience and Bioengineering 120(1):111-116;
Omranipour, H. M., Sajadi Tabassi, S. A., Kowsari, R., Rad, M. S.,
and Mohajeri, S. A. 2015. "Brimonidine Imprinted Hydrogels and
Evaluation of Their Binding and Releasing Properties as New Ocular
Drug Delivery Systems," Current Drug Delivery 12(6):717-725;
Cornwell, D. J., Okesola, B. O., and Smith, D. K. 2014.
"Multidomain Hybrid Hydrogels: Spatially Resolved Photopatterned
Synthetic Nanomaterials Combining Polymer and Low-molecular-weight
Gelators," Angewandte Chemie [Applied Chemistry] (International
edition in English) 53(46):12461-12465; Lauren, P., Lou, Y. R.,
Raki, M., Urtti, A., Bergstrom, K., and Yliperttula, M. 2014.
"Technetium-99m-labeled Nanofibrillar Cellulose Hydrogel for In
Vivo Drug Release," European Journal of Pharmaceutical Sciences
65:79-88; Liechty, W. B., Kryscio, D. R., Slaughter, B. V., and
Peppas, N. A. 2010. "Polymers for Drug Delivery Systems," Annual
Review of Chemical and Biomolecular Engineering 1:149-173; van
Bommel, K. J., Stuart, M. C., Feringa, B. L., and van Esch, J.
2005. "Two-stage Enzyme Mediated Drug Release from LMWG [low
molecular weight gelator] Hydrogels," Organic and Biomolecular
Chemistry 3(16):2917-2920; Roorda, W. E., Bodde, H. E., de Boer, A.
G., Bouwstra, J. A., and Junginger, H. E. 1986. "Synthetic
Hydrogels as Drug Delivery Systems," Pharmacy World and Science
[Pharmaceutisch Weekblad. Scientific Edition] 8(3):165-189). By
embedment or interleaving within collagen or absorbable polymers,
medication can also be released upon dissolution of the absorbable
materials. FIGS. 7, 8, and 9 show different expansion inserts, that
in FIG. 7 short and those in FIGS. 8 and 9 long, where both are
bisected to open at the point midway between the opposing edges of
a stent-jacket side-slit.
[2037] Materials available having widely variable spontaneous
dissolution times, or that are susceptible to breakdown on demand
with the application of an agent of dissolution by embedment or
layer apposition, or that can be disintegrated by lithotripsy, and
an ability to combine these materials in different ways, expansion
inserts can be provided to span over the expanded side-slit even
when curved or wide, as shown in FIGS. 8 and 9. Requiring only to
shrink in step with the postoperative resolution in swelling, most
expansion inserts are simple in consisting of a single segment or
layer rather than compound, and relatively narrow. When the
persistence of swelling is factor is unpredictable, dissolution on
demand materials are used. Smaller expansion inserts such as shown
in FIG. 7 when layered as shown in FIG. 8 are intended to
disintegrate in shorter or more tightly controlled intervals of
equal or different duration.
[2038] When one or more of the layers are susceptible to on-demand
(active, controlled) dissolution through the application of heat or
disintegration by lithotripsy, allowing for a period of subsidence
following the dissolution or disintegration of that layer requires
that the remaining layers have the material and bonding strength to
withstand the destruction process. In FIG. 7, the small insert is
materially and geometrically bilaterially symmetrical. Bisection
where one side or bridging arm is not encased within a layer of
another material has no effect on the free-to-bonded-end order of
dissolution of the materials; however, bisection at a point
intervening between the bond to the free edge of the base-tube
makes it possible to encapsulate the segments to the one side or
the other so that dissolution on that side will commence or be
initiated only after the other side has disintegrated.
[2039] While the stone layer will be the only one remaining of the
one expansion insert, agitation of lithotripsy can accelerate the
dissolution of a spontaneously absorbed elements impanted
elsewhere. Reciprocally, agitation can be used to accelerate the
dissolution of absorbable segments, although an ordinary hand
vibrator serves the purpose. Artificial stone can be used to encase
or envelop one arm or side so that its period for disintegration
will commence only after the other side has already disintegrated.
Alternatively, the casing or envelope can consist of a heat melted
matrix with or without a heat released solvent or induction
heatable particulate embedded. Artificial stone can also be
formulated for differential stone segment disintegration where
distinct periods of a duration too long for absorbable materials is
expected.
[2040] Substances that dissolve in serous fluid are dispersed most
quickly, with materials used to make absorbable suture absorbed
more slowly and formulable to shrink or waste at a rate that
assures persistence beyond the probable period for subsidence. The
latter incorporate a solvent embedded as small encapsulated
inclusions released when heated. The direct injection of a solvent
and vibration will also accelerate dissolution of absorbable
materials. The dissolution times of both kinds of material are
reduced by increasing the surface area by perforation or
dimensioning or increased by presentation as a block of greater
thickness. When subsidence is expected to take longer still or
never, stone is used. The different materials and shapes can be
sequenced and mixed to control the rate of stent-jacket contraction
in accordance with the reduction in diameter anticipated.
[2041] In FIGS. 8 and 9, free-edge or free-end segments or layers
113 and 114 can consist, for example, of crystalline sucrose (rock
candy') curved as to lap over the outer enzyme releasing hydrogel
adhesive, for example. In FIGS. 8 and 9, free-end segments 113 and
114 can also consist of polyglycolic acid, backed by layers 115 and
116 of hydrogel adhesive, for example, then base-tube fastened
segments 117 and 118 of glycolic-lactide copolymer, layers of
hydrogel adhesive, polycaprolactone, and layers of hydrogel
adhesive. Suitable stones for shock wave lithotripsy include
crystaline calcium oxalate monohydrate or dihydrate, calcium
phosphate, and ammonium magnesium phosphate salts synthesized for
disintegration by lithotriptor-generated shock waves (for such
distinctions in lithotriptor dosage essential to achieve the
breaking up of different stones, see for example, Bouropoulos, N.,
Mouzakis, D. E., Bithelis, G., and Liatsikos, E. 2006. "Vickers
Hardness Studies of Calcium Oxalate Monohydrate and Brushite
Urinary Stones," Journal of Endourology 20(1):59-63, and Johrde, L.
G. and Cocks, F. H. 1985. "Fracture Strength Studies of Renal
Calculi," Journal of Materials Science Letters
4(10):1264-1265).
[2042] An expansion insert or segment thereof that overlays a
lithotriptor-destructible material with a layer of an absorbable
material is considered equivalent to positioning an absorbable
layer side-slit free edge proximad to a gapward stone. When
subsidence nor the rate of subsidence can be predicted, consecutive
segments devised for selective destructability or differential
disintegration are used. Nonabsorbable, the layers of the insert
are prepared for selective disintegration, and when stone, need not
chemically duplicate stones of endogenous origin. Differential
resistance to ultrasonic disintegration is obtained by chemistry,
dimensioning, and extent of gas entrapment Vakil, N. and Everbach,
E. C. 1991. "Gas in Gallstones: Quantitative Determinations and
Possible Effects on Fragmentation by Shock Waves," Gastroenterology
101(6): 1628-1634).
[2043] To facilitate pulverization (disintegration, fragmentation),
stone inserts or layers thereof can be prebored or
pre-lithotripsied (pre-lithotresed). Lithotripsy cannot span an air
gap and requires continuity of medium for transmission from the
shockwave generator or source of excitation to the target. Unless
fluid-filled, the intervention of a body cavity will truncate
transmission of the waves, which must ensonify the target. To
affect the dissolution of an expansion insert material in a
stent-jacket surrounding an artery, synchronization to the systolic
pulse should not be necessary, and the process should work with
veins. In addition to pulverizing stony materials, lithotripsy can
accelerate the dissolution of nearby absorbable materials, which
can be used to advantage.
[2044] Since these neighboring non-stone materials can also release
medication, agitation by means of ultrasonic, and possibly pulse
laser lithotripsy can be used to release medication. Miniballs,
stays, and expansion inserts or the segments of these can consist
entirely of or incorporate absorbable materials that include
medication. However, any application of lithotripsy must not
dislodge miniballs or stays that have already been implanted within
the wall of the substrate ductus. Sufficient superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder can
be incorporated into any kind of miniball to allow its recovery by
means of the recovery electromagnets in the muzzle-head or
repositioning or holding in place with the aid of an extracorporeal
hand-held or probe extension from an imaging electromagnet, as
addressed above in section 4g entitled Emergency Recovery of
Miniballs and Stays and section X below entitled Steering and
Emergency Recovery of Implants with the aid of an External
(Extracorporeal) Electromagnet, among others.
[2045] Stent-jacket expansion inserts are simple when consisting of
a single span of uniform material and compound when consisting of
segments of different materials. The apposition and bonding of
segments of uniform internal composition affords sufficient
incremental control in any situation, individual segments
constituted for incremental dissolution internally unnecessary.
Depending upon the chemistry and configuration of the material or
materials of the insert and the medical condition of the patient,
the rate in breakdown or absorption will vary whether attributable
to enzymatic proteolysis (gut, collagen), hydrolysis (synthetics),
liquid infiltration, or chemical combination. Perforations to allow
the free passage of gas between the milieu and adventitia
significantly reduce strength and increase the surface area, hence,
the rate of dissolution.
[2046] These factors must be offset by the material used. In most
instances, single ply Type A (plain, nonchromic) catgut sheet in
the thickness needed to compensate for strength lost to any
`breathing` holes will achieve the breakdown time required, with
mild or light chromic catgut (Type B), medium chromic catgut (Type
C), or extra or heavy chromic (Type D) of like conformation
extending the breakdown period for a stent-jacket to be placed
about a small artery by about seven to ten additional days each in
the order stated. While absorbable suture must possess tensile
rather than compressive strength, experience with suture and more
particularly tissue engineering scaffolding indicates the
variability in persistence in different thicknesses of absorbed
implantable materials under various medical conditions.
[2047] The chemical environment, can be significantly altered in
disease and at a site of disease expression in particular, a given
absorbable material can vary in rate of dissolution. Materials
ordinarily used in absorbable suture vary in rate of dissolution
among individuals, and more so in patients with disease. Adding to
the unpredictability as to timing of subsidence, natural materials
(collagen, usually bovine or sheep gut, whether treated with
aldehyde solution and chromium trioxide to extend absorption time
as `chromic catgut`), degrade by proteolytic enzyme breakdown and
vary more in absorption time than do polyester based synthetics,
which degrade by nonenzymatic hydrolysis of ester bonds. Synthetics
are thus preferred as reducing overall unpredictability as to the
mean dissolution time of the materials to constitute the
stent-jacket expansion insert.
[2048] The volume and concentration of water and enzymes under
conditions of increased or reduced exudation or secretion, for
example, may be significantly altered. For example, a significant
factor in selecting short-term dissolution materials for
incorporation into the temporary expansion absorbable insert is
that the free water and enzymatic composition of serous fluid
differs in disease (see, for example, Ben-Horin, S., Shinfeld, A.,
Kachel, E., Chetrit, A., and Livneh, A. 2005. "The Composition of
Normal Pericardial Fluid and Its Implications for Diagnosing
Pericardial Effusions," American Journal of Medicine
118(6):636-640). Temperature also affects the rate of dissolution,
a high fever accelerating, and an ice table to lessen fever, for
example, reducing the rate.
[2049] When an extended period necessitates the use of an insert
material or materials that ultrasonic agitation would not
disintegrate, laser lithotripsy is used. Selecting the material and
dimensions of insert segments allows these to be arranged so that
base-tube contraction occurs in planned increments. An enlarged
ductus will ordinarily revert to the normal or nearly normal
diameter with healing over time. The same is true of an incipiently
aneurysmal elastic artery where the stent-jacket is essentially an
elastic bandage that consists of an ordinary polymeric or
copolymeric base-tube or a spandex backing with hook and loop
spandex straps without magnets or ductus intramural implants where
the mild constraint prevents the ductus from further enlargement
and encourages reduction.
[2050] To not seal off the outer surface of the ductus from the
surrounding cavity, the base-tube of an extrinsically magnetized
stent-jacket and the stent-jacket itself when intrinsically or
quasi-intrinsically magnetized is perforated and lined with
viscoelastic or moisture barrier-coated viscoelastic polyurethane
foam. When the internal surface of the expansion insert is in
contact with the ductus, these should be incorporated into the
expansion insert as well. When the swelling or the extent thereof
whether the result of implantation cannot be predicted with
confidence, implantation can precede placement of the stent-jacket,
which is the normal sequence and allows an interval to observe
whether swelling ensues. However, as addressed above in the section
entitled Circumstances Recommending the Use of a Shield-jacket or
Preplacement of the Stent-jacket, when implantation is ballistic,
there are numerous reasons for placing the stent-jacket before
initiating discharge. In that situation, an oversized stent-jacket
with thicker foam lining is used with or without expansion
insert.
[2051] The stent-jacket is supplied with different unitary or
monolithic expansion inserts to dissolve over different overall
periods. Expansion inserts to yield different increments and/or
overall periods for subsidence are also provided. These can be
preassembled; however, it is much more flexible or adaptable to a
given condition to provide an assortment of insert segments of
different materials and dimensions with suitable cements for local
assembly. Especially when high density implantation is used to
uniformly and more widely distribute the magnetic traction in order
to reduce the risk of pull-through or perforation of the ductus
wall, which may lack normal hardness, swelling may ensue,
necessitating wider retraction. If the ductus is so malacotic that
ballistic implantation is contraindicated, the use of stays should
be considered before replacement or bypass grafting.
[2052] I11b. Intracavitary Infusion of Fluid for Lithotriptor
Dissolution of Long-Term Controlled Destruction-Time Expansion
Inserts or a Final Stone Base-Tube Bonded Layer in Multilayered
Expansion Inserts
[2053] The use of stone to allow lithotripsy for controlling
stent-jacket contraction requires a second procedure, is suited to
sites where disintegration fragments can be retrieved or would be
innocuous if not retrieved, and is therefore undertaken only when
necessary. Long-term temporary stays used without a stent-jacket
are never made of stone. The use of electrohydraulic probes to
accomplish the lithotripsy is inadmissible. When not interposed by
a body cavity (potential space), lithotripsy coupling is
conventional (percutaneous, extracorporeal). This will rarely be
the case, vasa treated by the means herein described running just
beneath visceral serosae, and thus requiring cavitary infusion of a
shock wave propagation medium to achieve coupling.
[2054] Cavitary infusion is achieved either by injecting and
afterwards aspirating away the coupling medium with water or by
inserting a tightly rolled empty silicone cushion membrane through
a local laparoscopy sized entry wound, injecting the intracavitary
membrane with the medium, when so contained, preferably
ultrasonography jelly (Cartledge, J. J., Cross, W. R., Lloyd, S.
N., and Joyce, A. D. 2001. "The Efficacy of a Range of Contact
Media as Coupling Agents in Extracorporeal Shockwave Lithotripsy,"
British Journal of Urology International 88(4):321-324).
Postlithotripsy, the medium is suctioned (aspirated) away and the
cushion membrane if any retracted. Due to the risk of injury to the
subjacent adventitia of shock wave destruction, stone inserts are
recessed from the internal surface of the stent-jacket or
base-tube.
[2055] I11c. Absorbable Stent-Jacket Expansion Insert Materials
with Relatively Short Breakdown Times
[2056] Shorter-term materials in order of increased time for
dissolution or loss of compressive strength include:
[2057] 1. Glucose, dextran-40 and disodium
(1-4)-2-deoxy-2-sulfoamino- -D-glucopyranuronan (S-chitosan).
[2058] 2. Poly(ethylene glycol) and sugar (Wang, X., Yan, Y.,
Zhang, R., Fan, Y. W., Cui, F. Z., Feng, Q. L., and Liang, X. D.
2004. "Anastomosis of Small Arteries Using a Soluble Stent and
Bioglue," Journal of Bioactive and Compatible Polymers
19(5):409-419); and in order of increasing degradation.
[2059] 3. Polyglycolic acid.
[2060] 4. Polylactic acid.
[2061] 5. Polycaprolactone (Benicewicz, B. C. and Hopper, P. K.
1990. "Polymers for Absorbable Surgical Sutures--Part I," Journal
of Bioactive and Compatible Polymers 1(5):453-472; W. J. Ciccone
II, C. Motz, C. Bentley, and J. P. Tasto 2001. "Bioabsorbable
Implants in Orthopaedics: New Developments and Clinical
Applications," Journal of the American Academy of Orthopedic
Surgery 9(5): 280-288). Gut is not preferred, primarily because it
is less predictable as to its breakdown time. Other suitable
biocompatible and absorbable (biodegraded) aliphatic polyesters
include, for example,
[2062] 6. Poly D,L-lactic-co-glycolic acid, polyvalerolactone,
polyhydroxybutyrate, polyhydroxyvalerate,
polyhydroxybutyrate-hydroxyvalerate, and
polyhydroxybutyrate-hydroxyvalerate copolymer reinforced with
polyglactin 910 fibers.
[2063] Other stent-jacket expansion insert materials based upon
materials used in bioabsorbable suture, staples, endoluminal
stents, and tissue engineering scaffolds include: 1. Polyglactin
910, which can be treated for more rapid breakdown; 2.
Polydioxanone; 3. Poliglecaprone 25 (copolymer of glycolide and
E-caprolactone); and 4. Woven and various blends of polyglycolic
acid. Others such materials include Poly(lactide-co-glycolide) and
Poly(glycolide/L-lactide) (see also Jeong, S. I.; Kim, S. H.; Kim,
Y. H.; Jung, Y.; Kwon, J. H.; et al. 2004. "Biodegradable PLCL
Scaffolds for Mechano-active Vascular Tissue Engineering," Journal
of Biomaterials Science-Polymer Edition 15(5):645-660; Grayson, A.
C. R., Voskerician, G., Lynn. A., Anderson, J. M., Cima, M. J., et
al. 2004. "Differential Degradation Rates in Vivo and in Vitro of
Biocompatible Poly(lactic acid) and Poly(glycolic acid) Homo- and
Co-polymers for a Polymeric Drug-delivery Microchip," Journal of
Biomaterials Science-Polymer Edition 15 (10): 1281-1304; and Lee,
S. J., Lee, I. W., Lee, Y. M., Lee, H. B., and Khang, G. 2004.
"Macroporous Biodegradable Natural/Synthetic Hybrid Scaffolds as
Small Intestine Submucosa Impregnated
Poly(D,L-lactide-co-glycolide) for Tissue-engineered Bone," Journal
of Biomaterials Science-Polymer Edition 15(8):1003-1017);
polyhydroxybutarate valerate; polyorthoester; and
polyethylenoxide/polybutylene terephthalate.
[2064] I11d. Lithotriptor-Destructible Stone Stent-Jacket Expansion
Inserts and Differentially Destructible Expansion Insert Layers
[2065] When subsidence is premature or cannot be predicted, the
expansion insert or segments (layers) thereof must be dispersible
on demand. The object is to the extent possible to make the
stent-jacket self-contracting with the need for reintervention
forestalled if not eliminated but readily possible if necessary. To
avoid the need for further intervention, when subsidence is
predictable, the expansion insert or first to go segments thereof
are absorbable. Without further intervention, such as warming or
injection of a solvent, an expansion insert dissipated through
absorption will break down over a period that varies with the
chemical environment. Absorbable segments dissolve without
intervention but if necessary, can be dissipated on demand, as
addressed in the preceding section. When the term for subsidence
might exceed the persistence of absorbable materials, the expansion
insert is made of stone.
[2066] Intermediate levels of predictability are reflected in the
sequencing of segments, where only that terminal, made of stone,
may require intervention at a much later date, if ever. For a given
expansion insert, any absorbable segments will have been dispersed
before the stone layer remains; however, when other absorbable
elements are present, the effect upon these of the agitation
induced by lithotripsy must be taken into account, as must the
effect of energy and frequency or firing rate levels on
pull-through and delamination, and shock wave induced injury to a
vulnerable substrate ductus. Differential destructibility of
absorbable segments is based upon differential susceptibility to a
certain solvent, and/or heat, and/or vibration. Differential
destructibility of stone segments is based upon differential
susceptibility of different natual stones or differentially
formulated artificial stone to lithotriptor types as
electrohydraulic, laser, or pneumatic and settings.
[2067] To this end, natural or synthetic stone has the equivalent
of weakening microcracks introduced into it in a density and in an
intersecting pattern keyed to coalesce or nucleate so as to induce
failure after a time interval, and when applicable, in a layer
sequence preferred (Lokhandwalla, M. and Sturtevant, B. 2000.
"Fracture Mechanics Model of Stone Comminution in ESWL
[extracorporeal shock-wave lithotripsy] and Implications for Tissue
Damage," Physics in Medicine and Biology 45(7):1923-1940;
Rassweiler, J. J., Tailly; G. G., and Chaussy, C. 2005 "Progress in
Lithotriptor Technology," European Association of Urologists Update
Series 3(1):17-36; Zhu, S., Cocks, F. H., Preminger, G. M., and
Zhong, P. 2002. "The Role of Stress Waves and Cavitation in Stone
Comminution in Shock Wave Lithotripsy," Ultrasound in Medicine and
Biology 28(5):661-671; Cleveland, R. O and McAteer, J. A. 2007.
"The Physics of Shock Wave Lithotripsy," Part IV, Chapter 38 in
Smith, A. D., Badlani, G. H., Bagley, D. H., Clayman, R. V.,
Docimo, S. G. and 6 others (eds.), Smith's Textbook of Endourology,
St Louis, Mo.: Quality Medical Publishing Company, pages 326-328).
Such micropassages can be cut through the insert or a layer thereof
by means of pulsed laser microdrilling under multiaxial positional
control (see, for example, Clarke, J. A. and Profeta, J. III 2004.
"Laser Micro-Drilling Applications," in Roessler, D. and Uddin, N.,
Proceedings of the 2004 Advanced Laser Applications Conference and
Exposition, Volume 2, Saline, Michigan, available at
http://www.aerotech.com/pressbox/pdf/clarke_alac.pdf. and
http://www.metalase.com/Clarke-Profeta%20Paper.pdf).
[2068] Injury to tissue is reduced by lowering the amplitude and
frequency of shock wave delivery (Evan, A. P., McAteer, J. A.,
Connors, B. A., Blomgren, P. M., and Lingeman, J. E. 2007. "Renal
Injury During Shock Wave Lithotripsy is Significantly Reduced by
Slowing the Rate of Shock Wave Delivery," British Journal of
Urology International 100(3):624-628). Injury to tissue and blood
due to cavitation (see, for example, Bailey, M. R., Cleveland, R.
O., Colonius, T., Crum, L. A., Evan, A. P. and 4 others 2003. " The
Role of Cavitation in Tissue Injury and Stone Comminution in Shock
Wave Lithotripsy," Session 1H-2, Institute of Electrical and
Electronics Engineers International Ultrasonics Symposium
Proceedings, Transactions of the Institute of Electrical and
Electronics Engineers Ultrasonics, Ferroelectrics, and Frequency
Control Society) is additionally suppressed when the shock waves
are administered with a pressure release reflector insert placed in
the standard brass ellipsoid reflector (Evan, A. P., Willis, L. R.,
McAteer, J. A., Bailey, M. R., Connors, B. A., and 5 others 2002.
"Kidney Damage and Renal Functional Changes are Minimized by
Waveform Control that Suppresses Cavitation in Shock Wave
Lithotripsy," Journal of Urology 2002 168(4 Part 1):1556-1562). As
does the use of the use of lower frequencies (McAteer, J. A., Evan,
A. P., Williams, J. C. Jr., and Lingeman, J. E. 2009. "Treatment
Protocols to Reduce Renal Injury During Shock Wave :ithotripsy,"
Current Opinion in Urology 19(2):192-195), the use of a wide angle
focal zone lithotriptor evidently improves the effectiveness of
shock wave delivery at low frequency and amplitude levels (Evan, A.
P., McAteer, J. A., Connors, B. A., Pishchalnikov, Y. A., Handa,
and 5 others 2008. "Independent Assessment of a Wide-focus,
Low-pressure Electromagnetic Lithotripter: Absence of Renal
Bioeffects in the Pig," British Journal of Urology International
101(3):382-388).
[2069] Expansion inserts or segments for eventual extracorporeal
shock wave lithotripsy are generally in the multimillimetric if not
millimetric size range. Machined stones of biological or geological
origin provide sufficient material for many. Gallstones
(choleliths), which consist primarily either of cholesterol, or of
bilirubin and calcium salts, and urinary tract (kidney, ureteric,
and bladder) stones, which consist of calcium oxalate monohydrate
(whewellite) or dihydrate (weddellite); magnesium ammonium
phosphate hexahydrate (struvite), struvite-carbonate apatite, uric
acid, calcium phosphate, or cystine, are routinely harvested by
slaughter houses. Large urinary calculi such as renal staghorn
calculi and large gallstones are economically harvested at
lithotomy.
[2070] Natural stone tending to include defects, direct machining
yields numerous rejects. Therefore, when natural stone is used, it
is preferred to crush and reconstitute the stone under high
pressure using a biocompatible polymer binder such as polylactic
acid. The cost of different molds is avoided by producing a
standard sized block which is sectioned into differently sized
briquette blanks. Each blank is then micromachined to
specification, to include the disintegration micropassages or
tunneling indicated above. Provided it exhibits the brittleness or
lack of elasticity to fail when lithotripsied, a mineral such as
crushed hydroxyapatite (hydroxylapatite), obtainable in particulate
form for molding, allows the preliminary process of reconstitution
to be eliminated.
[2071] The adaptation of tissue engineering scaffold preparation
techniques even allows casting with interconnected channels (see,
for example, Ott, A. and Irlinger, F. 2009. "Hydroxyapatite Powder
Used for Rapid Prototyping in Medical Engineering," International
Journal of Computer Applications in Technology 36(1):32-37; Yang,
S., Leong, K. F., Du, Z., and Chua, C. K. 2001. "The Design of
Scaffolds for Use in Tissue Engineering. Part I. Traditional
Factors," Tissue Engineering 7(6):679-689). To allow differential
lithotripsy and thus controlled reduction in stent-jacket expansion
at intervals determined on the basis of diagnostic imaging of the
residual enlargement of the ductus, harvested and synthesized
calculi for use in multi-stone layered stent-jacket expansion
inserts, wherein the layers have different shock wave exposure
breakdown times, can be chosen based upon composition.
[2072] Breakdown times are addressed in the literature (see, for
example, Pelander, W. M. and Kaufman, J. M. 1980. "Complications of
Electrohydraulic Lithotresis," Urology 16(2):155-157). The greater
resistance to lithotripsy of calcium oxalate monohydrate compared
to dihydrate, for example, has long been recognized. Naturally
formed calculi can be modified in mechanical properties through
chemical treatment (see, for example, Johrde, L. G. and Cocks, F.
H. 1986. "Effect of pH on the Microhardness of Renal Calculi,"
Journal of Biomedical Materials Research 20(7):945-950). The
persistence of a change in hardness following implantation of a
calculus obtained from nature as the result of having been
chemically treated warrants investigation.
[2073] The extracorporeal preparation (synthesis) of calculi (see,
for example, Grases, F., Millan, A., and Conte, A. 1990.
"Production of Calcium Oxalate Monohydrate, Dihydrate or
Trihydrate," Urological Research 18(1):17-20; Lepage, L. and
Tawashi, R. 1982. "Growth and Characterization of Calcium Oxalate
Dihydrate Crystals (Weddellite)," Journal of Pharmaceutical
Sciences 71(9):1059-1062) can emulate the physiological conditions
under which these are produced in the body (see, for example,
Balaji, K. C. and Menon, M. 1997. "Mechanism of Stone Formation,"
Urologic Clinics of North America 4(1):1-11; Mandel, N. 1996.
"Mechanism of Stone Formation," Seminars in Nephrology
16(5):364-374) or can introduce extracorporeal innovations such as,
biocompatibility allowing, exercising control over the
morphological development of calcium oxalate dihydrate crystals
(see, for example, Zhang, D., Qi, L., Ma, J., and Cheng, H. 2002.
"Morphological Control of Calcium Oxalate Dihydrate by a
Double-Hydrophilic Block Copolymer," Chemistry of Materials 14
(6):2450-2457).
[2074] I11e. Expansion Insert Bonding Agents (Adhesives)
[2075] I11e(1). Intrinsic Shorter-Term Insert-to-Base-Tube and
Segment-to-Segment Bonding Agents
[2076] Where the materials to be bonded allow, an alternative to
the use of an adhesive is ultrasonic welding (Troughton, M. J.
(ed.) 2008. Handbook of Plastics Joining, a Practical Guide,
"Ultrasonic Welding," Norwich, N.Y.: William Andrew Publishing,
page 15). The strength of cement bonds is strengthed by scoring or
roughing up the surfaces and the cement chosen for the materials to
be bonded. Nonabsorbed cements must remain innocuous if left intact
and not break down into harmful degradation products. Cyanoacrylate
cements in accordance with the guidelines stated below in the
section entitled Extrinsic Shorter-term (Absorbable) to Longer-term
(Stone) Layer Bonding Agents have wide applicability. Absorbable
adhesives include polylactic acid (Ren, J. (ed.) 2010.
Biodegradable Poly (Lactic Acid): Synthesis, Modification,
Processing and Applications, Beijing, China: Tsinghua University
Press/Springer Verlag; Petrie, E. M. 2010. "Polylactic Acid
Biopolymer Adhesives," SpecialChem 24 Mar. 2010, at
http://www.specialchem4adhesives.com/resources/articles/article.aspx?id=3-
534), and polycaprolactone (Choi, W. Y., Lee, C. M., and Park, H.
J. 2006. "Development of Biodegradable Hot-melt Adhesive Based on
Poly-.epsilon.-caprolactone and Soy Protein Isolate for Food
Packaging System," LWT [Lebensmittel Wissenschaft and Technologie,
Schweizerische Gesellschaft fur]--Food Science and Technology
39(6):591-597).
[2077] At established temperatures and with suitable catalysts if
necessary, these and other absorbable materials commonly used for
suture and tissue engineering scaffolding as specified above, when
constituting the expansion insert segments to be bonded, exhibit
tackiness that makes these materials suitable for direct fusion as
hot-melt adhesives negating the need for an extrinsic glue (Ren, J.
Op. cit, Chapter 6, Section 6.5, "Biodegradable Hot Melt Adhesive
Based on PLA [Polylactic Acid] and Other Biodegradable Polymers,
pages 229-233; Stolt, M., Viljanmaa, M., Sodergard, A., and
Tormala, P 2003. "Blends of Poly(-caprolactone-b-lactic acid) and
Poly(lactic acid) for Hot-melt Applications," Journal of Applied
Polymer Science 91(1): 196-204; Viljanmaaa, M., Sodergardc, A., and
Tormalaa, P. 2002. "Lactic Acid Based Polymers as Hot Melt
Adhesives for Packaging Applications," International Journal of
Adhesion and Adhesives 22(3): 219-226; Leadbetter, K. J. and
Shalaby, S. W. 1993. "Study of Interfacial Bonding in Fiber
Reinforced Absorbable Composites," Journal of Bioactive and
Compatible Polymers 8(2):132-141). In addition to synthetic glues
and sealants such as cyanoacrylate, fibrin sealants and genetically
engineered polymer protein glues are also available.
[2078] I11e(2). Longer-Term Expansion Insert-to-Base-Tube and
Layer-to-Layer Bonding Agents
[2079] Longer-term insert-to-base-tube and layer-to-layer bonding
agents for bonding expansion inserts to persist over a longer
period, such as polymethyl methacrylate, must, as must shorter term
or absorbable adhesives, break down into harmless degradation
products or remain intact but innocuous. The maximum time of
segment persistence and the chemical environment of the material
used to bond the expansion insert to the base-tube and segments
together will be the primary determinants of the adhesive
dissolution time, so that expansion inserts in less intimate
contact with the environment are more likely to necessitate
noninterventional interventional measures as indicated above due to
persistence beyond the period desired. Long-term bonding agents are
thus better suited to the bonding of stone inserts to be actively
destroyed whenever desired. Persistence of adhesion in stone-to
base-tube polymer bonds is thus pertinent.
[2080] I11e(3). Extrinsic Shorter-Term (Absorbable) to Longer-Term
(Stone) Layer Bonding Agents
[2081] Long carbon chain cyanoacrylate adhesives as short as butyl
2-cyanoacrylate (B2-CA) can be used to bond one absorbable segment
to another, whether in the expansion insert or at the insert to
stent-jacket base-tube interface. Exceptionally,
isobutyl-2-cyanoacrylate (bucrylate) has been cited as a potential
carcinogen (Haber 2004; Nursal et al. 2004; and Samson and Marshall
1986, cited above in the section above entitled Specification of
Cyanoacrylate Tissue Sealants and Bonding Agents; Vinters, H. V.
Balil, K. A., Lundie, M. J. and Kaufmann, J. C. 1985. "The
Histotoxicity of Cyanoacrylates," Neuroradiology 27(4):279-291;
Vinters, H. V., Debrun, G., Kaufmann, J C , and Drake C. G. 1981.
"Pathology of Arteriovenous Malformations Embolized with
Isobutyl-2-cyanoacrylate (Bucrylate). Report of Two Cases," Journal
of Neurosurgery 55(5):819-825), and should not be used. The use of
cyanoacrylate cements is addressed below in the section entitled
Specification of Cyanoacrylate Tissue Sealants and Bonding agents,
as well as in other sections.
[2082] Depending upon the specific materials to be bonded and the
area and conformation of the contact surface, this kind of adhesive
will usually allow the bonding of an absorbable polymeric or
copolymeric segment to a stone segment, a stone segment to another
stone segment, or a stone segment to a stent-jacket base-tube. The
bonding of an absorbable polymer to stone as is used, for example,
when the stent-jacket is to remain for an indeterminate time. A
layer of stone can be deposited onto such a polymer (see, for
example, Yokoyama, Y., Oyane, A., and Ito, A. 2007. "Biomimetic
Coating of an Apatite Layer on Poly(L-lactic Acid); Improvement of
Adhesive Strength of the Coating," Journal of Materials Science:
Materials in Medicine 18(9): 1727-1734).
[2083] I12. Retardation in the Dissolution of Absorbable
Stent-Jackets, Stent-Jacket Expansion Inserts, and Stays
[2084] Whether used to make stent-jackets, stent-jacket expansion
inserts, or stays, absorbable materials suitable for implantation
can be modified to retard dissolution (see, for example, Maquet,
V., Boccaccini, A. R., Pravata, L, Notingher, I., Jerome, R. 2004.
"Porous Poly(alpha-hydroxyacid)/Bioglass Composite Scaffolds for
Bone Tissue Engineering. I: Preparation and In Vitro
Characterisation," Biomaterials 25(18):4185-4194; Maquet, V.,
Boccaccini, A. R., Pravata, L., Notingher, I., and Jerome, R. 2003.
"Preparation, Characterization, and In Vitro Degradation of
Bioresorbable and Bioactive Composites Based on Bioglass-filled
Polylactide Foams," Journal of Biomedical Materials Research. Part
A 66(2):335-346; Slivka, M. A. and Chu, C. C. 1997. "Fiber-matrix
Interface Studies on Bioabsorbable Composite Materials for Internal
Fixation of Bone Fractures. II. A New Method Using Laser Scanning
Confocal Microscopy," Journal of Biomedical Materials Research
37(3):353-362; Ibnabddjalil, M., Loh, I. H., Chu, C. C.,
Blumenthal, N., Alexander, H., and Turner, D. 1994. "Effect of
Surface Plasma Treatment on the Chemical, Physical, Morphological,
and Mechanical Properties of Totally Absorbable Bone Internal
Fixation Devices," Journal of Biomedical Materials Research
28(3):289-301; Assimos, D. G., Smith, C., Schaeffer, A. J., Carone,
F. A., and Grayhack, J. T. 1984. "Efficacy of Polyglycolic Acid
(PGA) Tubing Stents in Ureteroureterostomies," Urological Research
12(6):291-293, and this in conjunction with the timed release of
medication (see, for example, Tarcha, P. J. 1999. Polymers for
Controlled Drug Delivery, Boca Raton, Fla.: Chemical Rubber Company
Press division, Taylor & Francis). The immediate chemical
environment of the material as used in stays or expansion inserts,
for example, will be the primary determinant of the dissolution
time. In little if any contact with tissue, expansion inserts, for
example, are more likely to necessitate interventional measures due
to persistence beyond the period desired.
[2085] I13. Alternative Procedure to the Use of Expansion
Inserts
[2086] The use of an oversized jacket with thicker foam lining with
or without an expansion insert is addressed in the section above
entitled Expansion Inserts Absorbable, Meltable, and Comminutable
for Time-discrete Decremental Contraction of Stent-jackets. As an
alternative to the use of stent-jackets with expansion inserts, an
off-the-shelf absorbable endoluminal stent with an appropriate
dissolution time is placed for the period during which the ductus
is expected to remain swollen following discharge implantation
(see, for example, Waksman. R. 2007. "Promise and Challenges of
Bioabsorbable Stents," Catheterization and Cardiovascular
Interventions 2007 70(3):407-414; Waksman, R. 2006. "Biodegradable
Stents: They Do Their Job and Disappear," Journal of Invasive
Cardiology 18(2):70-74; Waksman, R. 2006. "Update on Bioabsorbable
Stents: From Bench to Clinical," Journal of Interventional
Cardiology 19(5):414-421.
[2087] Absorbable stents designed to minimize thrombogenesis and
the release of embolizing debris have already been described (see,
for example, Tamai, H., Igaki, K., Tsuji, T., Kyo, E., and four
other authors 1999. "A Biodegradable Poly-l-lactic Acid Coronary
Stent in the Porcine Coronary Artery," Journal of Interventional
Cardiology 12(6):443-450; Stack, R. S. and Klopovik, Z. P. 1994.
"Absorbable Stent," U.S. Pat. No. 5,306,286). Upon confirmation
that the temporary device has completely disappeared as by computed
tomography or intraductal ultrasound, a stent-jacket of the
presumptive healed or end-condition internal diameter is placed in
a followup procedure. If made, for example, of biodegradable
poly-l-lactic acid, the second procedure would generally follow the
first in about five months. In an artery, to reduce the risk of
restenosis into the absorbable stent as it disintegrates, whereby
substantial reocclusion would precede complete absorption making a
transluminal approach risk embolism, the stent should incorporate
in-stent intimal hyperplasia-suppressive medication (see for
example, Tsuji, T. 1., Tamai, H. 1., Igaki, K., Kyo, E. and seven
other authors 2003. "Biodegradable Stents as a Platform to Drug
Loading," International Journal of Cardiovascular Interventions
5(1): 13-16).
[2088] Other ductus present similar considerations (see, for
example, Tanaka, T., Takahashi, M., Nitta, N., Furukawa, A., Andoh,
A., Saito, Y, Fujiyama, Y., and Murata, K. 2006. "Newly Developed
Biodegradable Stents for Benign Gastrointestinal Tract Stenoses: A
Preliminary Clinical Trial," Digestion 74(3-4):199-205; Saito Y,
Tanaka T, Andoh A, Minematsu H, Hata K, Tsujikawa T, Nitta N,
Murata K, Fujiyama Y. 2007. "Usefulness of Biodegradable Stents
Constructed of Poly-l-lactic Acid Monofilaments in Patients with
Benign Esophageal Stenosis," World Journal of Gastroenterology
13(29):3977-3980). An absorbable endoluminal stent can release
medication such as steroidal to reduce any swelling. The absorbable
stent will usually be coated with anesthetic and antiplatelet or
anticoagulant medication as well. Medication is addressed below in
the section entitled Medicated and Medication Miniballs.
[2089] The incorporation into absorbable stents of medication is
under development (see, for example, Bunger, C. M., Grabow, N.,
Sternberg, K., Kroger, C., and seven other authors 2007.
"Sirolimus-eluting Biodegradable Poly-L-lactide Stent for
Peripheral Vascular Application: A Preliminary Study in Porcine
Carotid Arteries," Journal of Surgical Research 139(1):77-82.
Uurto, I., Mikkonen, J., Parkkinen, J., Keski-Nisula, L.,
Nevalainen, T., Kellomaki, M., Tormala, P., and Salenius J P. 2005.
"Drug-eluting Biodegradable Poly-D/L-lactic Acid Vascular Stents:
An Experimental Pilot Study," Journal of Endovascular Therapy
12(3):371-379; Tsuji, T., Tamai, H., Igaki, K., Kyo, E., and seven
other authors 2003. "Biodegradable Stents as a Platform to
Drug-loading," International Journal of Cardiovascular
Interventions 5(1):13-16). Exceptionally, in a ureter, where
standard practice calls for the placement of a nonabsorbable metal
endoluminal stent that clogs and must be replaced every few months
and the interim use of an absorbable stent is not an option,
implantation and the placement of an extraluminal stent are
accomplished ab initio. The lumen is then free of any foreign
object that would promote clogging and interfere with transluminal
recanalization or recannulation.
[2090] I14. Sectional, or Chain-Stents, Segmented and
Articulated
[2091] I14a. Purposes and Types of Chain-Stents
[2092] A sectional or chain-stent comprises a succession or train
of tied substents as intermittent or serial. The subsidiary
stent-jackets or substents connected by flexible ties, the stent as
a whole is able to follow a curved segment of a ductus without
distorting structure, and to accommodate movement about a hinge
joint (ginglymus) or ball and socket joint (enarthrosis,
spheroidea). Such a stent is intended to minimize interference with
normal physiology and simplify extension to as yet unaffected
(unlesioned) portions of a diseased ductus. As with a unitary
extraluminal stent, a sectional stent overall and in each of its
substents is comprised of intravascular and circumvascular
components. Ordinarily, the ductus-intramural implants (miniballs
or stays) are placed in apposite or complementary relation to the
substents; however, when speed is essential, as when wishing to
avoid the need for cardiopulmonary bypass, miniballs placed with
the aid of machine-controlled transluminal advancement and
discharge are laid down in a continuous formation.
[2093] As always, not all of the miniballs or stays associated with
a given stent-jacket, here a substent-jacket, need be of like
constitution. Miniballs can be placed before or after the
stent-jacket, whereas stays must be placed first. Advantages in the
use of articulated or chain-stents include entry through a single
incision, eliminating the need for separate entry and locating the
treatment site for each in a number of separate stent-jackets.
Sectional or chain-stents are either segmented or connected end to
end by suture or wire. Segmented chain-stents are cut into a
continuous length of tubing with a narrow bridge portion left to
connect the otherwise separate segments so that a given number can
be snipped off or trimmed as needed. The tubing can be discretely,
intrinsically, or quasi-intrinsically magnetized or laminated.
[2094] To resist the straightening urge of the elastic tubing, the
bridge portions of a segmented stent are kept narrow. While the
sub-stents in a segmented stent differ only in length or interval,
the sub-stents in such an assembled chain-stent can differ in any
or all properties. Substents in a segmented chain-stent will
ordinarily be alike in length and distance from one to the next.
Variability among substents is achieved by the free sequencing of
separate jackets as modules or links into a chain connected end to
end by suture or wire. In an assembled or nonsegmented chain-stent,
the interval separating the substents is based upon the diagnosis
and freely changeable from one substent to the next, each
sustent-jacket in the train is presequenced to overly its intended
location.
[2095] The variability among substents in a chain includes the
internal and external diameters and length of each, whether the
foam lining of each is wetted with the same or different drugs or
other therapeutic substances, stent-jacket resilience, type as
intrinsically, quasi-intrinsically, or extrinsically magnetized,
the field strength and medication of each, and the distance
separating each substent from the substent to its front and back.
Except for segmented chain-stents, which are cut from a continuous
length of tubing, the individual jackets or substents in a chain
can be distinct in virtually any way that one jacket can differ
from another, to include the use of side-straps, inclusion of an
expansion insert, and so on.
[2096] Moreover, a chain can include impasse- as well as radiation
shield-jackets and stent-jackets where each is matched to the
condition of the ductus at its respective site. This allows the
capability of each type jacket specified in the section above
entitled System Implant Magnetic Drug and Radiation Targeting to be
applied so as to maintain the ductus patent, drug-targeted, with
the impasse-jacket-suspended medicinal miniball or miniballs, for
example, noninvasively extractable to a safe location outside the
ductus or entirely out of the body. Additional advantages of serial
connection include multiple contact areas or anchoring that
prevents migration and can expedite the locating of a failed
substent if necessary.
[2097] Relatively free of the detractions pertaining to endoluminal
stents, a chain-stent arouses less concern for complications in
extension for prevention, such as to preempt a changing pattern of
vasospasm (see, for example, Wada, M., Hara, H., and Nakamura, M.
2006. "A Change in the Pattern of Vasospasm after Stenting in a
Patient with Vasospastic Angina," Heart and Vessels 21(6):388-391;
Li, Y., Honye, J., Takayama, T., and Saito, S. 2007. "Generalized
Spasm of the Right Coronary Artery after Successful Stent
Implantation Provoked by Intracoronary Administration of
Ergonovine," International Journal of Cardiology 119(2):251-254;
Kaku, B., Honin, I. K., Horita, Y., Uno, Y., Yamazaki, T., Funada,
A., and Ohka, T. 2005. "The Incidence of Stent-edge Spasm after
Stent Implantation in Patients with or without Vasospastic Angina
Pectoris," International Heart Journal 46(1):23-33), without added
risk thus averting the need for later procedure.
[2098] Not limited to a diameter slightly greater than that of the
lumen, an extraluminal stent to include a chain-stent is more
adapable than consecutive endoluminal stents. Unless an angioplasty
is to precede placement, the use of stays eliminates a transluminal
procedural component. At the same time, the lumen wall is nowhere
restrained as prevents normal movement and overlain as prevents
normal blood-endothelial chemical, such as hormonal, exchange. Not
interfering with normal function and thus posing the risk of
inducing pathology, extension for prevention using segmental and
preventive use more generally, using separate extraluminal stents,
are accomplished with less hesitancy. The same applies to other
type ductus where the prognosis indicates that additional lesions
are likely to appear in certain locations.
[2099] Another advantage in a segmented extraluminal stent wherein
each substent can differ in length and distance from its neighbors
is the ability to ride and/or straddle portions of ductus that flex
or are more densely supplied with small blood vessels, for example.
Articulated` chain stent-jackets are separately made stent-jackets
that are secondarily connected or strung together into a train or
chain, whereas `segmented` stent-jackets are cut into a continuous
length of tubing, with a connecting tab or band of the tube wall,
the bridge, running continuously from one segment to the next from
end to end. In an articulated or chain-stent, the ends of the
sub-stent connecting wires are secured by short barrel wide head
rivets situated toward the edges of the adjacent base-tubes so that
the wires pass from the outer surface of one sub-stent to the
next.
[2100] The distance from the end edges of adjacent sub-stent
base-tubes that the rivets are placed depends upon the resistance
to tearing of the base-tube based upon the strength and thickness,
of the base-tube material. Expansion inserts can be used with any
or every substent in a chain-stent of any kind. The rivets for the
connecting wires must be longitudinally and circumferentially
offset from the area of attachment of an expansion insert if
present. Somewhat oversized segmented stent-jackets that
incorporate thicker moisture barrier-coated viscoelastic
polyurethane foam linings allow placement in childhood that need
not be replaced to accommodate growth. Adjacent sub-stents render
the chain less susceptible to migration; in most instances, the use
of end-ties as addressed above in the section entitled Jacket
end-ties and Side-straps is not necessary.
[2101] In the harsh internal environment, the yield strength of the
bridge portions in a segmental chain-stent, with a large surface
area-to-volume ratio may, depending upon the material of which the
base-tube and integral bridge are made, degrade and fail. To
prevent this and the migration that would ensue, a fine wire of
nonmagnetic stainless steel attached by staples of the same metal
at intervals is run across the outer surface of the segmented stent
from end to end over the bridges. When the stent-jacket mounts
magnets, a wire runs parallel to the sides of these along the
bridges. The wire makes snipping off the number of substents needed
a little more difficult but assists in advancing the segmented
stent through the entry portal as addressed in the section to
follow. However, the bridges are not strengthened by lamination
with another layer of an elastic material nor increased in width,
since this either reduces the flexibility of the chain.
[2102] The addition of a wire requires that the number of
sub-stents to be used are cut off the continuous strip of substents
with wire cutters rather than scissors. Other sectional stents are
assembled for the specific application, the queue including jackets
connected with suture or stainless steel wire and rivets in
whatever sequence is wanted. The connecting wires extraluminal,
similarity to a jointed Palmaz-Schatz stent is meaningless. In
contrast to other sectional stent-jackets, segmented stent-jackets
are identical from one to the next. The miniballs or stays
associated with each substent-jacket, however, need not be the
same. The potential range of therapeutic variability from one to
the next is thus considerable, but less than that of other
sectional stent-jackets, which are more costly and must be
specially assembled for each patient.
[2103] To alter consecutive substent-jackets, as by varying the
strength of magnetization from one to the next, undoes the economy
of uniformity as an off the shelf device. As shown in FIG. 13, a
segmented chain-stent-jacket base-tube is provided in the form of a
continuous length of tubing 120 with the repetitive pattern of
substent-jackets having been cut into it. Continuous connecting
strip or bridge 121 runs along the top of the tube to connect the
substent-jackets in the segmented stent-jacket. The material of the
tube as shown is elastomeric with extrinsic magnets; however, a
segmented stent-jacket can be intrinsically magnetized, in which
case it is made of thin magnetizable stainless steel,
quasi-intrinsically magnetized, or magnetized by lamination or
coating, the constitution of each type addressed above in the
section entitled Types of Stent-jacket.
[2104] Jacket antimigration cinching straps or belts 122, referred
to as end-straps when fastened to connecting strip or bridge 121
portion cut off from a segmented chain-stent as shown in FIG. 14
and thus not overlapping the jacket, and side-straps when wrapping
about the jacket as shown in FIG. 15, are ordinarily strips of hook
and loop surfaced spandex. End and side-straps are fastened to the
stent-jacket with wide-head rivets 123. To cut off one or as many
continuous substent-jackets as the longitudinal extension or
potential extension of the condition warrants, tube 120 with
repetitive substent segments is cut with scissors or wire cutter
midway between the end-straps 122.
[2105] I14b. Procedure for Placement of a Chain-Stent
[2106] In placing a segmented chain-stent, the ductus is imaged as
necessary, any vessels or nerves to be left intact noted, and the
ductus freed of surrounding tissue as necessary. Unless the length
of the segment requiring treatment is extended, requires studied
dissection, or the number of vessels or nerves to be avoided
significant, two entry points are used. That proximal is used to
insert and advance the first or most distal substent, which is
moved past or advanced to lie directly beneath the more distal
entry point. Using one of the hand tools described in the section
below entitled Stent-jacket Insertion Tools, each successive
substent is opened around the ductus beneath the distal
incision.
[2107] The distal entry point is positioned to overlie a structure
to be avoided when present, the substents provided with a side-slot
of adequate width to pass the structure and one if not both
side-straps removed at the substent junction to straddle the
structure before entry. The insertion tool with illuminating
endoscope lashed alongside as necessary is introduced through this
second distal entry point where the leading substent is opened to
encircle the ductus. When the vessel or nerve to be avoided is deep
and not seen, the substents are marked to indicate the angle that
places the side-slot on the far side so that it will straddle or
clear and slide past the structure with the least contact.
[2108] The foam lining of the substents is wetted with a lubricant
such as ACS Microslide , Medtronic Enhance.RTM., Bard Pro/Pel.RTM.
or Hydro/Pel.RTM., Cordis SLX.RTM., or Rotaglide.RTM. if necessary,
so that once in encircling relation, pulling the first substent
while pushing the extracorporeal retinue or train of substents
forward or farther distal slides the second substent into position
for encirclement. The segmented stent is advanced by pushing the
proximal while pulling the distal end-substent to slide the stent
forward along the ductus until the next substent is positioned
beneath the incision. Buckling when pushing the promial end is
lessened by using a segmented stent with stainless steel wires
running along the top of the substent junctions of bridge sections.
When possible, drugs and any other therapeutic substances are
applied in a form that also contributes to lubricity or is
compatible with the lubricant.
[2109] The bridge sections can be of any length but are not
increased in length to allow these to be pulled away from the
underlying ductus for slipping one jaw of the cutting tool
underneath; instead, the bridge sections should be cut through
perpendicularly with only so much separation from the adventitia as
is needed to prevent injury thereto. The substents are slid past
the subsidiary structure until the substent junction or bridge
segment with side-straps removed straddles the structure leaving it
in the clear. When another subsidiary structure at a different
angle is to be avoided, the incision for insertion of the chain is
placed distal to it. Subsidiary structure that enter and depart the
substrate ductus at different angles are accommodated by cutting
the bridge between the adjacent substents and rotating these to
allow passage of the subsidiary ductus at the side-slot of
each.
[2110] The end side strap of one can be used to cinch the ductus
and that of the other to attach to the other side-strap after
having been trimmed of nonessential slack. Made with a spandex
backing and covered with hooks and loops, the terminal side-straps
of adjacent jackets that are separate with a subsidiary structure
between them can be fastened directly to one another, thereby
reducing any tendency to migrate. The number of substents required
along any one segment is not cut off the strip until closing. An
articulated chain-stent in a similar application is placed in the
same way. However, since the number of substents are made for the
application, a dummy proximal extension may be added if necessary
toassist in pushing the substents along. Also when such a
chain-stent must be advanced by pushing and pulling it along the
ductus, wires of sufficient inflexibility to allow the chain to
pushed forward are used.
[2111] I15. Miniball and Ferrofluid-Impassable Jackets, or
Impasse-Jackets
[2112] I15a. Uses of Impasse-Jackets
[2113] Impasse-jackets, or impasse and extraction jackets, serve
either of two purposes, and compound miniball-impassable jackets
usually include at least one jacket to serve each purpose. One
purpose is to act as a prepositioned endarterial, intravenous, or
intrabronchial trap or guard, termed a trap-, guard-, stopping-
-jacket or -collar, that will seize and prevent further passage of
a miniball or miniballs that enter the circulation upsteam. The
other purpose is as a holding jacket to suspend susceptible
miniballs and nanoparticles in the lumen, this type more likely to
be radially asymmetrical as to magnetic field strength to draw a
drug carrier bound drug, for example, into an eccentric tumor, for
example. Drug nanoparticles and drug carrier nanoparticles can be
introduced upstream in a ferrofluid or released from a
miniball.
[2114] Magnetically susceptible matter is drawn into the ductus
wall while the nonsusceptible is carried forward. Thus, a miniball
is drawn up against the ductus wall where it can initiate the timed
release of drug carrier nonoparticles that will be drawn into the
ductus wall over a segment contingent upon the holding jacket
strength of magnetization or medication from that level for passage
downstream. An impasse-jacket must not only stop but facilitate the
extraction of a miniball without injury to the substrate (treated)
ductus, almost always an artery. To avert the stopping of a
miniball precariously at the ends of the jacket or the sudden
levering or end-pushing of the jacket under the pull of the
external extraction electromagnet, magnetization of the jacket is
concentrated at its center and the jacket extended to encircle a
longer segment of the ductus.
[2115] Moisture barrier-coated viscoelastic polyurethane foam
end-cuff linings in the impasse-jacket and similarly lined
dummy-collars or outriggers as described below, securely fit the
jacket to the ductus while affording additional flexibility in
ductus and/or jacket diameter resulting in good compliance while
preventing injury to the ductus from the mesh. Dummy-collar type
outriggers differ from end-tie outriggers or end-tabs in being
braced, that is, bridged by stainless steel bridge pieces as seen
in FIG. 16, extending the anti-levering stabilization out to the
ends of the triad. The need for inflexibly or hard-braced
impasse-jacket type outrigger anchors to resist levering or
end-suture tethered end-tie type end-tabs (end-collars) to prevent
migration along the ductus depends upon the preexisting strength of
the connection of the ductus to the surrounding tissue.
[2116] A miniball loose in any other type ductus, such as in the
airway, is not swept forward and is therefore quickly apprehended,
rarely if ever allowing the need to preposition a trap-jacket
downstream. Continued movement of a miniball through the
circulation may bode the misdirection of radiation, medication, or
another bioactive substance to tissue downstream from the level
intended, and whether a permanent miniball or one absorbable but
not disintegrable on demand, embolization. Of these, blockage poses
the least risk; due to the small size of miniballs in proportion to
the level along the vascular tree to which these are targeted, were
a miniball loose in the circulation to proceed unchecked,
embolization would result well downstream.
[2117] At this level, collateral circulation is almost always
abundant, dispelling significant risk, and retraction to a safe
internal location or extraction from the body relatively simple and
safe, as addressed below in the section entitled Stereotactic
Resituation of a Mispositioned Miniball. Whether to place an
impasse-jacket is thus a matter of judgment based upon the
potential adverse consequences of mispositioning a miniball of
specific content. Impasse-jackets not only prevent such an
eventuality midprocedurally, but if nonabsorbable, indefinitely.
Any stent-, impasse-, or magnet-jacket can attract magnetically
susceptible-bound matter and thus serve for magnetic drug-targeting
when appropriate.
[2118] In some instances, the requirement for magnetic strength to
accomplish this may disallow the concurrent use of the jacket for
stenting, because the more powerful traction might result in
pull-through and/or delamination. An impasse-jacket includes at
least one ductus-encircling member, or jacket, which is magnetized
in the radial direction relative to the long axis of the jacket.
Since an impasse-jacket must trap a miniball that approaches it,
impasse-jackets are chained only when a single jacket may lack the
necessary space for plural mijniballs and the blood is sufficient
to force miniballs forward to the next jacket. When the jacket must
allow the miniball trapped within it, usually one nonabsorbable, to
be extracted, the strength of jacket magnetization is greatest at
the center and dropped off moving toward the ends.
[2119] In longer specimens, the end segments are not magnetized. To
prevent injury to the substrate ductus as the result of levering in
a powerful magnetic field used for extraction, magnetization thus
and the addition of securing and anti-levering outrigger jackets
(end-cuffs, end-collars) essentially snipped off from the ends of
the impasse-jacket or of the kind used with end-ties are applied.
That is, these measures combine to secure and stabilize the ends of
the impasse-jacket during an extraction so that the long axis of
the jacket remains perpendicular or normal to the electromagnet and
aligned, rather than levering, in relation to the substrate ductus.
As gratuitously disallowing other uses in the future once placed,
uniform magnetization end to end is generally discounted, even when
the immediate application involves only absorbable miniballs.
[2120] Accordingly, the prospects for future treatment of the
specific patient should decide whether an impasse-jacket will be
absorbable or magnetized over its entire length. Extraction applies
to the removal of a miniball that should be removed, such as one
containing a radioisotope or a potent drug that was to have been
targeted. A miniball trapped by the jacket having been dislodged
upstream as the result of a direct blow or passing through a strong
magnetic field, for example, can often be left in the jacket
indefinitely. An impasse-jacket for use with high dose-rate seed
miniballs can be provided with a radiation shield formulated to
disintegrate on demand, thus exposing the underlying cribriform or
sieve configured extraction grid (filter screen, grating) to allow
extraction, as addressed above in the section entitled Noninvasive
Dissolution on Demand of Absorbable Stent-jackets, Base-tubes, and
Radiation Shields.
[2121] The mesh material of a nonabsorbable extraction grid can be
made as is an intrinsically magnetized stent-jacket of spring
stainless flat sheet stock, as addressed above in the section
entitled Intrinsically Magnetized Stent-jackets. If the grid is to
be coated, such as with a neodymium impregnated polymer, then the
mesh size on die punching must take into account the reduction in
mesh size imparted by the coating. Magnetization then is not
uniform as in the case of the stent-jacket but rather stronger at
the center and reduced moving out toward either end. The magnetized
sheet is then sectioned with a shears and the halves of the
impasse-jacket formed on a mandrel. Alternatively, each
half-cylinder of the jacket can be magnetized separately.
[2122] The entire internal and external surfaces at and about the
central circumference are of like polarity and repel so long as
either side does not form a closed local magnetic circuit through
miniballs within the jacket to either side. Accordingly, the
restorative force of the spring-hinge that closes the jacket about
the ductus is selected to overcome the tendency for opening due to
the repulsion of the opposing poles at every diameter. Except for
the removal of a high dose-rate seed or potent drug miniball,
extraction is seldom if ever necessary. Moreover, even in the
bloodstream, the jacket will retain a number of miniballs
indefinitely, extraction needed to preclude obstruction when the
result of improperly introducing a larger number of miniballs not
destructible on demand than the jacket was designed to retain.
[2123] Impasse-jackets thus suspend radiation or medication
miniballs in the circulation or prevent emergencies, allowing
resituation or extraction of miniballs in unusual circumstances if
and when these pose a risk. Provided extraction through the wall of
the ductus is unlikely to spread sepsis that could not be quickly
eradicated, an external electromagnet allows a miniball or
miniballs trapped or held in an impasse-jacket--to be extracted
noninvasively through the wall of the ductus and mesh, the
extraction grid or extraction grating, of the impasse-jacket to a
point outside the ductus where the miniball would be innocuous, or
entirely to the magnet outside the body.
[2124] The means to accomplish this are addressed above in the
section entitled Emergency Recovery of Miniballs and Stays and in
section X2c below entitled Stereotactic Arrest and Extraction of a
Circulating, Dangerously Mispositioned, or Embolizing Miniball.
Whether the primary or later as an unforeseen object, once placed,
a stent-jacket, impasse-jacket, or magnet-jacket constitutes not
only a prepositioned magnetic miniball trap, but can be used as a
radiation or drug-targeting device. In this capacity, it may be
used alone or with other such jackets for staged targeting, as
addressed below in the section entitled Cooperative Use of
impasse-jackets in Pairs and Gradient Arrays.
[2125] Extraluminal, a stent- or impasse-jacket can incorporate a
larger mass of magnetized material to present a much more powerful
magnetic field than might a radiation-emitting endoluminal stent.
The extraluminal stent is not only able to attract drug carrier
nanoparticles, for example, from a ferrofluid infused upstream, but
critically, because it is located behind rather than in front of
the lesion such as a plaque in the lumen wall, the jacket draws the
drug carrier nanoparticles, for example, into the lesion rather
than stands between, attracts, and therefore precisely blocks the
direct transendothelial path into the lesion.
[2126] An absorbable such as polyurethane based miniball or stay
that releases ribonucleic acid nanoparticles resistant to enzymatic
breakdown such as gene silencing can be directly infixed in the
lumen wall to accomplish nonmagnetic transfection of small
interfering ribonucleic acid, for example, in vivo (see, for
example, Nelson, C. E., Gupta, M. K., Adolph, E. J., Shannon, J.
M., Guelcher, S. A., and Duvall, C. L. 2012. "Sustained Local
Delivery of siRNA from an Injectable Scaffold," Biomaterials
33(4):1154-1161; Tokatlian, T. and Segura, T. 2010. "siRNA
Applications in Nanomedicine," Wiley Interdisciplinary Reviews.
Nanomedicine and Nanobiotechnology 2(3):305-315; Higuchi, Y.,
Kawakami, S., and Hashida, M. 2010. "Strategies for in Vivo
Delivery of siRNAs: Recent progress," BioDrugs: Clinical
Immunotherapeutics, Biopharmaceuticals, and Gene Therapy
24(3):195-205).
[2127] A ductus-intramural miniball or stay or a miniball
formulated thus suspended within the lumen by a holding or
stent-jacket can be used to release magnetic drug carrier-bound
gene silencing ribonucleic acid nanoparticles thereby causing the
medication to be drawn into the lesion or tumor by magnetically
assisted transfection (see, for example, Plank, C., Zelphati, O.,
and Mykhaylyk, O. 2011. "Magnetically Enhanced Nucleic Acid
Delivery. Ten Years of Magnetofection--Progress and Prospects,"
Advanced Drug Delivery Reviews 63(14-15):1300-1331; McBain S C, Yiu
H H, Dobson J. 2008. "Magnetic Nanoparticles for Gene and Drug
Delivery," International Journal of Nanomedicine 3(2):169-180;
Bertram, J. 2006. "MATra--Magnet Assisted Transfection: Combining
Nanotechnology and Magnetic Forces to Improve Intracellular
Delivery of Nucleic Acids," Current Pharmaceutical Biotechnology
7(4)277-285; Takeda, S., Terazono, B., Mishima, F., Nakagami, H.,
Nishijima, S., and Kaneda, Y. 2006. "Novel Drug Delivery System by
Surface Modified Magnetic Nanoparticles," Journal of Nanoscience
and Nanotechnology 6(9-10):3269-3276; Morishita N, Nakagami H,
Morishita R, Takeda S, Mishima F, and 4 others 2005. "Magnetic
Nanoparticles with Surface Modification Enhanced Gene Delivery of
HVJ-E Vector," Biochemical and Biophysical Research Communications
334(4):1121-1126; Plank, C., Schillinger, U., Scherer, F.,
Bergemann, C., Remy, J. S., Krotz, F., Anton, M., Lausier, J., and
Rosenecker, J. 2003. "The Magnetofection Method: Using Magnetic
Force to Enhance Gene Delivery," Biological Chemistry
384(5):737-747).
[2128] Reference to silencing ribonucleic acid should not be taken
to exclude the transfection of nucleic acid in other forms, to
include deoxyribonucleic acid, messenger, double stranded, small or
short hairpin ribonucleic acid, oligodeoxyribonucleotide, and that
virus-bound. Single stage and multistage magnetic drug-targeting
are addressed above in the section entitled System Implant Magnetic
Drug and Radiation Targeting. An impasse-jacket that releases
radiation and/or is used to retain radioactive miniballs at a
certain level or segment of the ductus includes an encircling
radiation shield. The shield is formulated either to spontaneously
disintegrate according to the duration of irradiation prescribed or
upon effective depletion of the radiation source seed-miniball or
to be disintegrable on demand, as addressed above in the section
entitled Noninvasive Dissolution on Demand of Absorbable
Stent-jackets, Base-tubes, Radiation Shields, and Miniballs.
[2129] Most miniballs and stays are too small to incorporate a
tuning or segregably addressable function such that only one in a
group might be selectively disintegrated or otherwise controlled
such as to steer it. Differential steerability, for example, would
allow miniballs to be distributed to different points about the
luminal circumference encircled by an impasse-jacket to preserve
patency as a temporary stent with absorbable components or one for
long term use where the miniballs are extracted. Graduating the
magnetically susceptible content in miniballs affords a degree of
selectability for entrapment within one in a succession of
impasse-jackets where each exerts greater tractive force than that
preceding it. Miniballs are addressed by aiming a magnetic field
and limited to the focus thereof.
[2130] The interposition of tissue disallows the use of lasers and
infrared transmission, for example, to control miniballs. An
impasse-jacket can be used to trap and suspend in the lumen
medicinal or irradiating miniballs at a selected level of a ductus,
usually a blood vessel, in order to target treatment at and/or
downstream from that level. The noninvasive disintegrability on
demand if medicinal and/or extractability at will of the miniball
or miniballs suspended thus also distinguish this approach from the
use of either an internal or an external radiation or medication
emitting collar or stent and makes possible the short-term use of a
dose-rate higher than that of conventional seeds, which left to
decay, must be limited in dose-rate and life.
[2131] Miniballs injected into an artery upstream of the jacket
incorporate sufficient ferrous content for magnetic arrest, and
when to be noninvasively heatable, this content has continuity.
Upon reaching the jacket, the miniball is drawn against the lumen
wall. With increased magnetic strength, the miniball pushes the
wall outward, exerting a patenting or stenting effect without the
need for ductus-intramural placement, but uncontrolled as to
circumferential position. Where this does not matter, an isolated
vasculitis-induced potentially necrotizing atresia, for example,
can be held patent thus with both the impasse-jacket and miniball
disintegrated when no longer needed.
[2132] The magnetic strength of an impasse-jacket is not set so
high that an intact miniball would be drawn into a ductus-intramual
lesion risking delamination and pull-through; rather, the drug
carrier nanoparticles the miniball releases are drawn into the
lesion. By heating a holding jacket used thus as addressed above in
the section entitled Implants that Radiate Heat on Demand, it is
possible to accelerate the dissolution of a drug or other
therapeutic substance coating of the suspended miniball and the
uptake or other action of this substance by the diseased tissue.
The miniball can itself be made disintegrable on demand, as
addressed above in the section entitled Noninvasive Dissolution on
Demand of Absorbable Stent-jackets, Base-tubes, Radiation Shields,
and Miniballs.
[2133] Holding jackets allow held medication miniballs to be
extracted at any time. Suspended miniballs can dissolve
spontaneously or on demand. Releasing a counteractant or
neutralizer from a miniball or miniballs suspended by a holding
jacket or holding jackets downstream from the releasing miniball or
mniballs holding jacket makes it possible to mark off lengths of a
ductus for targeted treatment by drugs in different combinations
and in higher concentration than could be infused to circulate
throughout the body. Shallow miniballs can be heated locally from
outside the body and deep miniballs remotely to control the rate of
drug release, and the segments jacketed can be heated to accelerate
drug uptake. When extracorporeally energized by eddy-current
induction or radiofrequency resonance, holding jackets, just as
miniballs and stays, can be made to radiate heat.
[2134] Unless miniballs that can be controlled from outside the
body or that spontaneously respond to the condition of the blood
flowing past are used negating the need therefor, extraction
permits instant extractability in the event of an adverse drug
reaction. Assigning miniballs releasing different drugs to
different holding jackets allows the discretionary extraction of
any one drug or if one drug is divided among miniballs, reduction
in the dose. Other methods for quickly retrieving a medication,
bioactive substance, or radiation miniball which induces an adverse
reaction are addressed in the section below entitled Cooperative
Use of Impasse-jackets in Pairs and Gradient Arrays.
[2135] Except in dimensions, simple impasse-jackets and individual
jackets in braced; compound (doubled, doublet); and chain, or
triple or more impasse-jackets, addressed below in the section
entitled Braced, Compound, and Chain Impasse-jackets, are identical
in structure whether used to trap or to hold miniballs.
Impasse-jackets for suspending drug and/or radiation delivery
miniballs in the bloodstream, for example, can be made absorbable
with a polymeric mesh (extraction grid, extraction grating) and
magnetized with a chemically isolated lanthanoid (rare earth)
substance, usually neodymium iron boron. A permanent mesh in a
jacket less strongly magnetized can be made of magnetizable
stainless steel wire magnetized in the centrally concentrated
pattern indicated. Strongly magnetized impasse-jackets can be made
of a nonabsorbable polymer which is impregnated or overlain with
the encapsulated neodymium in the centrally concentrated pattern
indicated.
[2136] In an absorbable impasse-jacket, the magnetized
ferromagnetic material at the jacket midpoint must be encapsulated
for chemical isolation upon breakdown. While isolated, the
magnetized material is nonabsorbable, and the mesh grid wires
cannot be made as fine as when made of intrinsically magnetized
stainless steel. Should an absorbable device be preferred, suitable
polymers for use in absorbable implants, to include impasse-jackets
which can release substances on dissolution, are specified, for
example, in the section above entitled Absorbable Base-tube and
Stent-jacket, Miniball, Stay, and Clasp-magnet Matrix Materials and
that below entitled Absorbable Stent-jacket Expansion Insert
Materials with Relatively Short Breakdown Times, among others.
[2137] One-time dose applications should be supported by absorbable
jackets with a life expectancy somewhat in excess of the interval
for drug release. Ballistic delivery allows absorbable miniballs to
be implanted in a dense formation. In order not to remain as a
residue, an absorbable jacket hinge-spring must also be made of an
absorbable polymer with intrinsic and/or conformation-imparted
resilience and shape-memory. The moisture barrier-coated
viscoelastic polyurethane foam lining is treated to encourage
macrophage degradation, as addressed above in the section entitled
Materials Suitable for Rebound-directing Double-wedge Linings, the
absolute amount of 2,4-toluenediamine residue trapped within the
barrier and far too little to act as a carcinogen, as addressed
above in the section entitled Preliminary Description of the
Invention.
[2138] To best fit the ductus treated, the individual jackets in a
given compound or chain impasse-jacket can differ in length and
diameter, for example, and those in a chain jacket can differ in
the interval separating these constituent jackets. Impasse-jackets
can be interposed among stent- or shield-jackets in a chain wherein
every unit differs or serves a different purpose. For emergency
interception and extraction midprocedurally using a preplaced
impasse-jacket or an external electromagnet, sufficient
ferromagnetic material must be dispersed throughout an absorbed, to
include a drug-releasing miniball, so that its magnetic
susceptibility does not degrade with its dissolution to the point
where it is no longer extractable. For arrest and extraction, the
ferrous material is ordinarily superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder; for heat
induction, iron grains.
[2139] Uniform distribution also affords greater iron particulate
surface area for absorption and eliminates any need to extract a
relatively large core. When uniformly dispersed through the
miniball, the residual iron content essential to preserve magnetic
susceptibility attrites in step with the medication, the reduced
mass and volume necessitating less tractive force to prevent being
carried forward in the circulation. To allow immediate extraction
to a safe location or extraction entirely out of the body at any
moment, the extraction grid mesh size must be slightly larger than
the original diameter of the miniball. More specifically, to allow
the immediate removal of any miniball that might enter the jacket
and to accommodate radioactive miniballs which do not dissolve, the
mesh size of each impasse-jacket along a given ductus should be
large enough to extract the largest miniball that might necessitate
extraction from that jacket.
[2140] Miniballs that might enter the jacket are those for which a
given jacket of reference will be that first encountered. Types and
combinations of medication which can be incorporated into miniballs
are generally indicated in the section above entitled Field of the
Invention, and basic terms used to describe the different types of
impasse-jackets defined at the end of the section above entitled
Terminology. Individual impasse-jackets in simple and compound
jackets and those incorporated into chains with stent-jackets are
structually alike but can differ in mesh size, overall dimensions,
and function. Simple or non-compound impasse-jackets used to trap a
miniball loose in the circulation are referred to functionally as
simple-trap-jackets, while those used to suspend medication or a
radioactive source in the lumen, even when drawn from the passing
contents and thus trapped, are functionally referred to as simple
holding jackets.
[2141] Trap and holding jackets may be structurally
indistinguishable, but an asymmetrical holding jacket is
eccentrically magnetized to draw medication into an eccentric
lesion, whereas a trap-jacket is eccentrically magnetized to
situate the trapped miniball or miniballs toward the body surface
for extraction with the aid of an external electromagnet. However,
when the lesion is medial (toward the midsaggital plane) or
midfrontal (toward the midcoronal plane), the jacket is oriented
accordingly, the field strength increased to pull the trapped
miniball through the extraction grid along the greater distance
from the opposite side of the body. While extraction can withdraw
the miniball entirely outside the body, it is rarely beyond the
closest safe location outside the ductus.
[2142] Either type impasse-jacket may omit magnetized content over
all but a small arc entirely. Compound impasse-jackets used to hold
medication are compound holding jackets, and compound holding
jackets that include one or more trap-jackets are composite or
mixed jackets. Numerous alternative terms for a simple holding
jacket are possible, to include simple retention-jacket, simple
retention-collar, simple holding-collar, simple-retainer, and
simple holder, simple binding-jacket, and simple-binder. When not
simple or simple-extended (braced), the terms compound, chain, and
mixed or composite are substituted for `simple.` Thus, one can have
a simple-extended or braced impasse-jacket that includes only one
trap or one holding jacket, a compound impasse-jacket that includes
two trap or two holding jackets, a mixed compound jacket that
includes one trap and one holding jacket, or a mixed chain that
includes at least one trap and one holding jacket, the terms collar
and jacket interchangeable.
[2143] For this reason, chain jackets can be triple traps, triple
holders, or mixed triple, quadruple, and so on. With a holding
jacket, radioactive miniballs introduced upstream can be suspended
at jacket level in the lumen to emit radiation at that level, which
depending upon the depth of radiation penetration, can involve the
contents of the lumen, if any, the tunics of the lumen wall, and
tissue surrounding the lumen wall. Radioactive and medicinal
miniballs suspended in the vascular tree at the approach to a
certain organ can medicate or irradiate the blood bound for that
organ, for example. The need for a larger dose than one or a few
miniballs can deliver, or the advisability of isolating each
distinct type of therapeutic miniball is satisfied through the use
of a compound hold and trap chain impasse-jacket, as addressed in
the section to follow.
[2144] Isolation in a separate holding jacket allows differential
access for extraction and post-insertion interaction such as by
injecting substances just upstream from the isolating jacket.
Compound and chain jackets can include component jackets to trap
any miniballs that might, for example, be unintentionally released
into the bloodstream during discharge or intentionally released to
charge the jacket with a medication miniball, for example, by
direct injection just upstream to the jacket. Impasse-jackets thus
have primary functions as the object of implantation and afford
protection from the loss downstream of a miniball during and
following insertion. An impasse-jacket used as a guard or trap
where the number of upstream miniballs could not occlude it need be
no more than singular whether simple, braced, or a unit member in a
compound.
[2145] While the release into the circulation of a miniball is
unlikely, the strength of magnetization of any one trap-jacket
should not be so extreme that the jacket could become occluded if
overwhelmed by the entry of multiple miniballs over a brief
interval. The ideal strength of magnetization allows both the
retention of miniballs and attraction of drug carrier
nanoparticles. The propulsive force of the contents must shortly
dislodge those at the center of the lumen forcing these through the
jacket to the next trap-jacket downstream. A situation whereby more
miniballs are introduced into the bloodstream than the jackets
available could accommodate is impermissible, no upstream number of
miniballs should be allowed in any one unit member or component
holding jacket in a compound impasse-jacket that would not be
safely trapped by the next downstream component trap-jacket in the
compound, and so on.
[2146] Broadly, no one jacket should be given potential exposure to
more miniballs than it or the jacket which immediately follows it
could stop without becoming obstructed. In a composite
impasse-jacket used to maximize the dose by using a sufficient
number of miniballs, or to clearly demarcate each type therapeutic
agent by segregation into separate holding jackets, holding and
trap jackets will usually alternate and the miniballs will be
introduced by injection into the holding jackets through separate
hypodermic syringes or catheters fitted with a hypotube at the
distal tip between the proximate ends of the jacket fore and aft,
that is, at the bridges which serve to connect the consecutive
jackets in the compound.
[2147] The bridging in braced, compound, and mixed impasse-jackets
allows spanning past anatomy such as attachments best left intact
and points of flexion that would interfere with extending a simple
jacket lengthwise for improved stability in an extraction. When the
number of miniballs to be injected, whether a greater distance
upstream or in the trap-jacket immediately preceding is small
enough and the probability of a need for interception slight, only
the last or most downstream of the component impasse-jackets need
serve as a trap. Since a compound impasse-jacket is inherently
elongated, hence, stabilized or braced, adding nonmagnetized
dummy-collars or outriggers at either end of the compound as might
be needed to stabilize an isolated unit impasse-jacket through
connection by means of rigid in-line mesh-edge to edge bridge-arms
should not be necessary.
[2148] Unlike a compound or chain impasse-jacket which contains
consecutive holding jackets, a compound or chain guard (chain
guard-jacket, chain guard-collar) or chain-trap (chain trap-jacket,
chain trap-collar) seldom has two or more impasse-jackets in
succession; whether an isolated unit or member of a composite
impasse-jacket, each trap-jacket must be capable of preventing the
passage of any miniball that would otherwise pass. A compound
impasse-jacket may thus contain more than one trap-jacket where
each is intended to prevent the passage of miniballs released by
the constituent holding jacket in the compound immediately upsteam
to it should any be released during injection. Exceptionally, a
compound jacket can use consecutive constitutent-jackets as traps
when the first could become occluded.
[2149] In that case, the strength of magnetization of the first
trap must be less than would be able to retain miniballs at the
long axial center against the advancing force of the luminal
contents, usually, that exerted by the blood pressure. Increasing
the strength of jacket magnetization can be accomplished by using a
thicker and/or more strongly magnetizable fabric (mesh material) or
by coating the mesh with a polymer that incorporates an
encapsulated lanthanoid particulate, usually of neodymium iron
boron. In the bronchi, with embolization little threatening and
readily remedied, the tractive and retentive field strength
required is proportionally less. While impasse-jackets are intended
primarily for use in the vascular tree, suitably configured
impasse-jackets are no less applicable to other type ductus,
regardless of the purpose intended or the conditions
encountered.
[2150] For example, in the gut, where peristalsis exerts powerful
contractive forces behind the bolus, which expands the ductus, an
impasse-jacket is kept shorter to less restrain the longitudinal
action under the relatively greater strength of magnetization
required to keep the miniball or miniballs held in the lumen by the
holding jacket from being pulled from the jacket and swept away by
the passing bolus. The duration and longitudinal extent of the
disruption relative to the severity of the disorder must determine
each case on an individual basis. In the gastrointestinal tract,
expulsion spontaneous, extraction of a mispositioned or dropped
miniball that does not emit radiation should never be necessary.
Nonabsorbable miniballs lodged in a diverticulum or ruga may
require extraction, which can be accomplished transluminally.
[2151] If realized midprocedurally, recovery is with the same
barrel-assembly used to discharge the miniball; if
postprocedurally, the a barrel-assembly or a magnet probe ended
catheter is used. When the injury risked is slight, a miniball
containing potent medication that should not be misdirected or a
high dose-rate miniball to have been suspended in a holding jacket
with absorbable radiation shield with the potential to injure
healthy tissue may require immediate transmural extraction raising
concerns for the release of septic contents into the surrounding
body cavity. When the holding impasse-jacket is placed prior to
discharge, the radiation shield will also act as a perforation
shield to prevent a perforating miniball from carrying septic
contents out of the tract.
[2152] Even when the miniball does perforate into the cavity or
must be transmurally extracted, the absolute amount of bacterial
inoculum spread into the exit wound, much less any spillage into
the surrounding cavity will be minute, certainly in relation to
conventional procedures that incise an suture or staple (see, for
example, Watanabe, A., Kohnoe, S., Shimabukuro, R., Yamanaka, T.,
Iso, Y., and 7 others 2008. "Risk Factors Associated with Surgical
Site Infection in Upper and Lower Gastrointestinal Surgery,"
Surgery Today 38(5):404-412). The use of impasse-jackets as traps
to extract loose miniballs from a ductus wherein the contents are
septic, such as in the intestines or a vessel conveying infected
blood, is therefore contingent upon the ability of the immune
system and antibiotics to ward off infection.
[2153] Antimicrobials (antibiotics, viricides, fungicides or
mycocides, and/or fungistats) can be delivered on and/or within the
miniball itself as well as by other routes. Nonabsorbable miniballs
are usually given a deeply textured surface to encourage tissue
infiltration and adhesion. These tiny trenches retain a liquid such
as an antibiotic wetted onto the surface by capillarity. When the
perforation might liberate not just sepsis but metastatic seed
cells, nonintrusive transluminal extraction with the aid of a
powerful external (extracorporeal) electromagnet is discounted,
recovery then transluminal with a catheter having a magnet at the
tip or the recovery electromagnets in a radial discharge
barrel-assembly.
[2154] The use of impasse-jackets to retain irradiating or
medicinal miniballs at certain levels in the gut or in the
treatment of a carcinoma in any ductus should always contemplate
the need for emergency extraction using transluminal means. In
situations where the dislodging of the miniball would pose the risk
of adverse consequences, a perforation shield is used and the
strength of magnetization increased. In a blood vessel, a
nonabsorbable miniball that embolizes will do so at a gauge with
collateral circulation, so that extraction is based on the
discomfort or dysfunction experienced. If the miniball delivered
medication or radiation where it would be harmful, it is
extracted.
[2155] Introduced at a sharp angle to undercut and lodge beneath
abluminal tissue, drawn outward by the stent-jacket, having a
surface devised for infiltration by the surrounding tissue,and
optionally bonded in position by means of a protein solder made to
flow immediately after placement or a quick-setting surgical
cement, a miniball or a radoiactive seed core thereof, for example,
is unlikely to enter the lumen. Nevertheless, a midprocedural
equipment malfunction, human error during discharge, the rebound
into the lumen off of the lining of a stent-jacket prepositioned to
avert a perforation, later disease, or a direct blow, such as to a
carotid or coronary artery, could result in luminal entry.
[2156] Such a circumstance warrants the downstream prepositioning
of a means for preventing a miniball from passing a limit point and
retaining it in a safe position for removal with minimal trauma.
Postprocedural extraction is by trapping the miniball in a
downstream impasse-jacket and using an external electromagnet to
noninvasively pull the miniball out through the lumen wall and the
magnetized mesh-surround (extraction grid) of the impasse-jacket to
a safe location. A stent-jacket could trap and retain a miniball in
a fixed position within the lumen, but its perforations are not
configured to allow extraction. A trap-jacket is placed before the
stent-jacket and initiating implantation discharge. However
improbable the necessity, an impasse-jacket downstream from a stent
with multiple miniballs must have the potential to remain fully
functional despite repeated extractions, and without significant
injury to the substrate ductus.
[2157] An impasse-jacket must not deform nor a chain-guard or chain
impasse-jacket bow despite repeated extractions. Whether to serve
as a trap (guard) or luminal retention device, the diameter of an
impasse-jacket, which always has marginal or end cuff linings of
moisture barrier-coated viscoelastic polyurethane foam, is chosen
to allow the adventitial microvasculature, small nerves, and
perivascular fat to be encircled without significant compression.
The warmth of the tissue enhances the property of the foam of
enwrapping or investing these surface features. While veins
normally collapse during diastole, the foam end cuff linings are
sized to prevent migration, even when the caliber at each end
reflects tapering. Absorbable and nonabsorbable impasse-jackets can
be used in coordination with or independently of ductus
wall-infixed miniballs or stays.
[2158] The medication positioned can be layered, time-released,
adjuvant or neutralizing in relation to drugs or bioactive
substances systemic or released from other sources, and/or include
a radioactive seed miniball at a fixed level. Holding jackets that
release medication from suspended miniballs to work in a
coordinated manner can define a segment of any length in the
vascular tree where the downstream jacket may release a substance
to neutralize that released by the first so as to define the
intervening segment for treatment, or the second jacket can release
an agent to activate the first for treatment initiated at its
location. When this segment is relatively short, both or all
jackets can be strung together in a chain. The constancy of
circulation makes such coordinated use optimal in the circulatory
system.
[2159] Placement of an impasse-jacket about a vessel is local using
laparoscopic technique without a transluminal component, and the
introduction upstream of the radioactive and/or medicinal miniball
or miniballs is by injection. The gastrointestinal tract affords a
corresponding washing over effect only when boli sweep past, but
allows jacket charging and supplementation with other substances
noninvasively through ingestion. While requiring laparoscopic
insertion, an impasse-jacket can be used, for example, to position
a radioactive seed-miniball alongside a tumor or inside the artery
or arteries that supply it, then noninvasively extracted whenever
desired, allowing a higher dose-rate than would the use of an
endoluminal irradiating stent or seed, which left in place, must
decay within a limited time, and will continue to disallow
compliance with the pulse when the artery may itself have become
diseased.
[2160] For example, rather than to ligate the gastroduodenal and/or
hepatic arteries, a radioactive seed held within one or both
vessels is used to irradiate blood going to the liver (see, for
example, Bacchetti, S., Pasqual, E., Crozzolo, E., Pellarin, A.,
and Cagol, P. P. 2009. "Intra-arterial Hepatic Chemotherapy for
Unresectable Colorectal Liver Metastases: A Review of Medical
Devices Complications in 3172 Patients," Medical Devices (Auckland,
New Zealand) 2:31-40; Homsi, J. and Garrett, C. R. 2006. "Hepatic
Arterial Infusion of Chemotherapy for Hepatic Metastases from
Colorectal Cancer," Cancer Control 13(1):42-47; Lee, Y. T. 1978.
"Nonsystemic Treatment of Metastatic Tumors of the Liver--A
Review," Medical and Pediatric Oncology 4(3):185-203; Fortner, J.
G., Mulcare, R. J., Solis, A., Watson, R. C., and Golbey, R. B.
1973. "Treatment of Primary and Secondary Liver Cancer by Hepatic
Artery Ligation and Infusion Chemotherapy," Annals of Surgery
178(2):162-172). Local irradiation rather than ligation of the
supply may prove safer (see, for example, Kanashima, R., Nagasue,
N., Kobayashi, M., and Inokuchi, K. 1977. "Tumor Embolism in the
Right Atrium after Hepatic Artery Ligation for Hepatoma," Japanese
Journal of Surgery 7(4):246-252). Alternative methods require
recovery of a strongly irradiating source surgically, and
percutaneous needle injection of a radionuclide into the liver
disperses without eradicating migratory cancer stem cells before
these reach the liver.
[2161] Similarly, while primary carcinoma of a blood vessel is
uncommon (see, for example, Blackmon, S. H., Rice, D. C., Correa,
A. M., Mehran, R., and 8 others 2009. "Management of Primary
Pulmonary Artery Sarcomas," Annals of Thoracic Surgery
87(3):977-984; Lygidakis, N. J., Bhagat, A. D., Sharma, S. K.,
Kefalourous, H., Porfiris, T., and 7 others 2007. "Leiomyosarcoma
of the Inferior Vena Cava--An Unusual Case,"
Hepatogastroenterology. 54(75):710-717), to reduce the risk of
metastasis to a supplied organ, the site of the lesion and a point
or points along its drainage are irradiated. Migratory cancer stem
cells (see, for example, Davis, S. J., Divi, V., Owen, J. H.,
Bradford, C. R., Carey, T. E., Papagerakis, S., and Prince, M. E.
2010. "Metastatic Potential of Cancer Stem Cells in Head and Neck
Squamous Cell Carcinoma," Archives of Otolaryngology--Head and Neck
Surgery 136(12):1260-1266) approaching an organ supplied through
this artery are irradiated in transit, with the `seed` miniball or
miniballs noninvasively extracted on depletion.
[2162] Additionally placing a radiation emitting jacket with
radiation shield fitted affords aggressive treatment. The
impasse-jacket is inserted laparoscopically. For use along a ductus
closed off to the exterior, such as a blood vessel, ureter, or vas
deferencs, miniballs to be suspended within the holding jacket are
introduced by direct injection just upstream to the respective
jacket, the procedure involving no transluminal component. The
addition of miniballs may be deferred to a later procedure wherein
the bright contrast dye marked jacket or jackets are located
fluoroscopically, for example. Ordinary saline solution is used to
advance the miniball or miniballs to be suspended within a given
jacket to the tip of the hypodermic needle. The miniball or
miniballs delivered through a given needle need be alike only in
diameter; however, visibility wanting, each miniball whether the
same is injected separately.
[2163] A single impasse-jacket on the esophagus or gut is charged
by ingestion of food containing the miniball or miniballs. To pass
a first or proximal jacket in order to charge one distal thereto
requires the use of an endoscope, whereas tracheobronchial
placement is accomplished with the aid of a tracheoscope or
bronchoscope. When a compound or chain impasse-jacket that includes
plural holding jackets is used to accommodate a larger number of
miniballs or to isolate different medicinal or radioactive
miniballs in different individual jackets, each miniball or load of
miniballs is separately injected at a point along the component
jacket-to-jacket bridge-arm just upstream from each respective
target holding jacket.
[2164] A barrel-assembly may be used to the load a holding jacket
placed about a ductus that should not be perforated by injection;
however, multiple recharging is better accomplished through
injection at more distant locations upstream. For one or a few
charges, an absorbable impasse-jacket is used, while for treatments
at any future time, a nonabsorbable impasse-jacket is used. In a
holding impasse-jacket, the magnetic force retains the miniball in
suspension, and when the miniball releases drug carrier
nanoparticles, it attracts the nanoparticles into the ductus wall;
otherwise, the drug is moved downstream. Since impasse-jackets have
no endovascular component, these can be placed around a thin-walled
vein or over a segment of a ductus too diseased to be implanted
with miniballs or stays.
[2165] Such a jacket can be used to deploy and hold a radioactive
seed, medicinal, or combination miniball introduced with the aid of
a barrel-assembly to target a lesioned segment without infixion of
the miniball within the lumen wall, allowing treatment of a ductus
too malacotic for ductus-intramural implantation. Medicinal
miniballs that dissolve in the passing blood are taken up according
to their metabolic significance, so that some may be absorbed by
the endothelium, which others taken up by a certain organ or gland.
The dose progressively depleted thus, it is much reduced if not
eliminated once cycled through the circulatory system. The choice
of an absorbable or nonabsorbable impasse-jacket is based upon the
duration of the longest prospective treatment and need for
retreatment.
[2166] Absorbable impasse-jackets are made of neodymium iron boron
particulate-impregnated materials such as those specified above in
the sections entitled Field of the Invention and Absorbable
Base-tube and Stent-jacket, Miniball, Stay, and Clasp-magnet Matrix
Materials, and that below entitled Absorbable Stent-jacket
Expansion insert Materials with Relatively Short Breakdown Times,
among others, and provide the advantage of not requiring surgical
recovery. To assure uniform magnetization, each half-cylinder
comprising the impasse-jacket with encapsulated neodymium embedded
in the absorbable matrix is rotated before the magnetizer.
[2167] In general, nonabsorbable miniballs and those absorbable
re-administered over a long period are supported downstream by a
nonabsorbable impasse-jacket, whereas absorbable miniballs
containing only medicinal or other therapuetic ingredients to
disintegrate postprocedurally are supported by an absorbable
impasse-jacket. A miniball can be prevented from continued travel
past a trap-jacket only so long as the impasse-jacket remains
intact; were it to appear that this interval had been
underestimated, the miniball could be extracted immediately in the
same manner as would a stenting miniball stopped by a permanent
impasse-jacket. An impasse-jacket must remain functional as long as
it is reqired to prevent the loss downstream of a miniball.
[2168] Thus, when the period that a miniball with a dissolution
time greater than the maximum that might be required is used and
the time it is to be suspended is indeterminable, an absorbable
impasse-jacket with a dissolution time in excess of the life of the
miniball and not just the maximum prospective duration the drug
will be required should apply. A nonabsorbable impasse-jacket is
made with an extraction grid of fine magnetizable stainless steel
wire. When the wire itself cannot be magnetized to provide the
required field strength, chemically isolated premagnetized
lanthanoid granules embedded in an adherent matrix polymer is
coated onto the wire in the centrally concentrated pattern
indicated, care taken to occlude as few mesh (extraction grid)
openings as possible.
[2169] For use with a radiation emitting seed miniball, the holding
jacket is provided with an absorbable radiation shield that
protects the surrounding tissue and disintegrates to expose the
underlying extraction grid when the miniball is to be noninvasively
extracted to a point outside the ductus or the body with minimal
trauma. Retrievability allows the use of an unconventionally high
dose-rate. When multiple seed miniballs must be used in succession,
the persistence of the shield extends over the succession and is
then eliminated spontaneously or on demand to clear the way for the
depleted miniballs to be removed. An absorbable impasse-jacket is
itself absorbed or disintegrated, disallowing future use but
eliminating any need for reinvasive retrieval. It must persist
longer than the radioactive seed or successive seeds it is to
retain, then the dissolution of its radiation shield, allow the
seed or seeds to be noninvasively extracted.
[2170] An absorbable mesh is made of an absorbable polymer or
copolymer such as those specified above in the section entitled
Absorbable Base-tube and Stent-jacket, Miniball, Stay, and
Clasp-magnet Matrix Materials, formulated for optimal strength and
incorporating lanthanoid granules, for example. Comminutable and
meltable materials are addressed below in the sections entitled
Expansion Inserts Absorbable, Meltable, and Comminutable for
Time-discrete Decremental Contraction of Stent-Jackets and
Absorbable Stent-jacket Expansion insert Materials with Relatively
Short Breakdown Times. Absorbable impasse-jackets are the same in
configuration as the equivalent nonabsorbable impasse-jackets, to
include the outriggers of braced impasse-jackets described below in
the section entitled Braced, Compound, and Chain
Impasse-jackets.
[2171] To protect against human error, such as mispositioning the
needle when injecting miniballs for suspension in holding jackets
or improperly setting the discharge velocity as to result in
rebound into the lumen following discharge for ductus-intramural
implantation, the release of any miniball in the vascular tree best
takes the added precaution of prepositioning an adjustable external
electromagnet downstream, which can stop and extract these, as
addressed in the section above entitled Emergency Recovery of
Miniballs and below in the section entitled Use of an External
Electromagnet to Assist in Mishap Recovery. Whereas absorbable
stent-jackets can be allowed to disintegrate following a treatment
period during which the ductus heals whether ductus-intramural
implants were absorbable or nonabsorbable, absorbable
impasse-jackets without the backup of nonabsorbable trap
impasse-jackets downstream must not be allowed that would
disintegrate postprocedurally while a miniball remains suspended
within it.
[2172] The mesh size should just frame about and allow the largest
miniball to be suspended to pass through. During an extraction with
an extracorporeal electromagnet prepositioned downstream, a
trap-jacket restrains the ductus from being pulled, twisted, and
stretched until the shear strength or resistance to extraction
perforation of the wall is exceeded and the miniball is forced
through. Significantly, since the strength of the magnetic field
that can be directed at the miniball is extreme, a suddenness of
outward acceleration that would fail to preclude any ability of the
ductus wall to pose self-traumatizing resistance by stretching is a
distinct improbability. Accordingly, the need for a jacket is
proportional to the susceptibility of the ductus to injury. An in
situ perforation resistance test to indicate suitable mesh size and
the tractive force range essential to extract a miniball of given
diameter at that point is provided below in the section entitled
Testing and Tests.
[2173] Shock penetration through the sudden application of a
powerful magnetic extractive force is essentially the opposite of
ballistic insertion and prompted for the same reasons as specified
above in the section entitled Preliminary Description of the
Invention. Whereas the emergency interception and extraction of a
miniball loose in the circulation by means of an external
electromagnet with or without an impasse-jacket is noninvasive,
placement of the impasse-jacket is invasive, as addressed above in
the section entitled Emergency Recovery of Miniballs, and in
section X2c below entitled Stereotactic Arrest and Extraction of a
Dangerously Circulating, Mispositioned, or Embolizing Miniball.
Usually a length of downstream ductus will be available for
prepositioning a powerful external electromagnet that is well able
to withstand extraction without the need for an impasse-jacket;
however, once placed the jacket will continue to guard against
embolizing miniballs and suspend any introduced for treatment.
[2174] While the miniball to be extracted is usually withdrawn in
increments to a safe location just outside the ductus by pulsing
the electromagnet, provided no vulnerable structure such as a
ganglion is situated along the prospective extraction path, removal
can be entirely outside of the body. If moved to a location
unintended but safe, the miniball is allowed to remain. If lodged
behind bone, tendon, or ligament, the miniball can usually be left
in place; if not, then it is extracted in a different direction.
Since the perforation path or trajectory is minute in diameter,
usually about 0.4 millimeters, quickly seals, the electromagnet is
adjustable to a field strength high enough to extract the miniball
directly, and systemic platelet blockade is minimized as the
targeting capability of the apparatus allows, small vessels
intervening along the path that are torn soon heal.
[2175] The possibility that the a miniball on discharge with
perforation or extraction will punture and enter the lumen of a
second vessel to enter the circulation is eliminated by the
strength of the magnetic field, which pulls the miniball entirely
through the intervening ductus regardless of the blood pressure, or
in the gut, for example, the effective increase in tissue strength
due to contraction or the propulsive force the bolus. Even polymer
coated, the mesh in a nonabsorbable or absorbable impasse-jacket
poses no issue of obtrusive thickness as would encroach upon or
abrade neighboring tissue. It can therefore be made of strong
materials in sufficient thickness and strongly magnetized.
[2176] The miniball must be extractable through the lumen wall and
the mesh by a magnetic field of sufficient force to effect such
action, which will depend primarily upon the strength of the ductus
wall, for which an in situ test is provided in the section below
entitled Testing and Tests. Stretching injury to the ductus is
reduced when the mesh size as coated is just large enough to allow
the miniball to pass through. In an artery, the impasse-jacket can
be positioned as closely to the stent-jacket as any significant
interaction between the magnetic fields of a prospective extraction
electromagnet (qv.), the stent, and impasse-jacket would allow. A
benefit in close placement or including both stent- and
impasse-jackets as a braced pair is that both the stent and
impasse-jacket can be inserted through the same if elongated entry
wound.
[2177] To minimize injury to the substrate ductus and to the
neighboring tissue, the impasse-jacket must not lurch or lever
under the magnetic force that the extraction electromagnet must
exert to overcome the perforation resistance of the lumen wall.
Unless a mineralized deposit intervenes, this condition is easily
met, even when the ductus is severly sclerosed due to disease. In
the arterial tree, wherein the antegrade caliber of the vessels
progressively diminishes centrifugally, or from the heart to the
periphery, placement of the impasse-jacket as close as practicable
to the stent-jacket can stop the miniball at a level where the
impasse-jacket, whether simple or braced, can be longer and
stronger both structurally and in magnetization and the miniball is
still small in diameter relative to the caliber of the ductus.
Extraction at this level is also located farther upstream from the
level of eventual embolization and where the artery is more
robust.
[2178] While generally thin-walled and unsuited to
ductus-intramural or intraparietal implantation, these relations
are reversed in veins, where continued antegrade travel moves the
miniball through levels of increasing caliber. In the venous tree,
positioning the impasse-jacket at a greater distance from the
stent-jacket stops the miniball where it is closer to the center
where the vein is larger, so that an extraction poses less risk of
trauma at the immediate location and is more easily viewed. If the
miniball did lodge in a lung, at about 0.4 at millimeters in
diameter, its emergency extraction path, would almost certainly
close spontaneously never to require extraction, and even if
extraction, which from a lung must be passed thuough the pleura,
were required, the risk of a pneumothorax or pneumoserothorax for a
perforation of this diameter may be discounted.
[2179] Exceptionally, the use of a stent-jacket with
rebound-directing lining in an artery, as addressed above in the
section entitled Double-wedge Stent and Shield-jacket
Rebound-directing Linings, may warrant backup by a
miniball-impasse-jacket situated downstream from the stent-jacket
to stop any miniball that rebounded into the lumen despite the
intervening double-wedge. Symptoms improbable, prospective or
prognostic consequences determine whether periodic imaging is
advisable to detect the presence of a stopped miniball in an
impasse-jacket that would justify extraction; provided the miniball
is small for the lumen and tightly held by the magnetic field, it
can usually be left.
[2180] Lkewise in a vein, the average gauge of the ductus over the
treatment segment, diameter of the miniballs used, and mesh size of
the impasse-jacket will be proportional, and the degree of
positional stability required of the impasse-jacket during an
extraction dependent upon the force to be exerted by the extraction
electromagnet. The extraction grid is intended to restrain the
miniball from stretching To minimize the force of extraction needed
and movement of the impasse-jacket, the mesh size with any coating
should be optimized for the diameter of the miniball in relation to
the perforation resistance of the ductus wall. While each case must
differ in the degree of extractive force required, to ensure that
the impasse-jacket and any bracing will not fracture, bow, or
otherwise deform despite an unexpectedly untested sclerosed area of
the wall, the material strength and thickness of the mesh is
overrated.
[2181] Each half of the impasse-jacket magnetized normal to its
long axis, its radially outward polarity will be uniform about the
circumference of the completed jacket. The jacket thus presents a
net repulsive moment in relation to the tractive force exerted by
the external extraction electromagnet. This repulsion serves to
push the impasse-jacket back against the subjacent tissue as the
same force extracts the miniball. This stabilization by repulsion
prevents traumatic levering, wrenching, kinking, stretching or
choking off of the lumen at the jacket margins as well as the
tearing of any underlying attachment desired to be kept intact.
Stabilization by suturing, which would have to be deep, awkward
through the small access portal, and increase the risk of
infection, is thus unnecessary.
[2182] Since the extraction grid or mesh is configured for the
least resistance to passage therethrough, the miniball is
essentially restrained only by the resistance posed by the lumen
wall that stands between it and the extraction electromagnet. Too
large a mesh can allow a more elastic wall to resist extraction by
stretching, for example. Properly sizing the mesh to the diameter
of the miniball minimizes stretching injury to the wall. Extraction
with the least tractive force reduces the risk of excessive jacket
repulsion that could injure the ductus and/or damage the
impasse-jacket itself. Jackets used to attract drug carrier
nanoparticles must present greater field stength than those used to
attract mniballs, which can include a much larger amount of
susceptible content; however, only miniballs require
extraction.
[2183] The strength of impasse-jacket magnetization may be limited
by proximity to other implants susceptible to a magnetic field.
This may force the prepositioning of an impasse-jacket in the
arterial tree, for example, farther downstream and/or set a limit
to how strongly the jacket can be magnetized. A jacket to be
capable of attracting susceptible nanoparticles may have to be
positioned farther downstream. However, the strength of
magnetization must always be sufficient for the maximum momentum of
a miniball or susceptible particulate that might enter the lumen
upstream, in an artery, at the systolic blood pressure. More
specifically, for a miniball of given mass and diameter, the
maximum propulsive force exerted by the pulse depends upon the
blood pressure and the effect of gravity at the location and
position of the implantation site.
[2184] In the esophagus, the downward driving force on the bolus is
the determinant. Most often, the application of stent and stopping
jackets is not accomplished during open surgery, but rather through
a laparoscopic entry wound or `keyhole` incision of a few
centimeters. Small joint arthroscopic type instruments--and
exceptionally when a wider impasse-jacket is inserted with its two
sides then having to be folded to encircle the ductus, a
stent-jacket insertion tool, as described below--are used to insert
and position the jacket. Access thus restricting the manipulative
range of the operator, the conformation and placement of
impasse-jackets are devised to minimize the manipulation needed
even with braced impasse-jacket secured off to either end by a
dummy-collar or outrigger, as will be described.
[2185] For example, to expedite placement where working space is
lacking, any dummy-collars, or outriggers needed to reduce
levering, as addressed below in the section entitled Braced
Impasse-jackets, are structurally unitized with the impasse-jacket
at the center and inserted as a unit. If placed with an open
surgical field, end-tie type end-tabs can be used. Increased
susceptibility to the tractive magnetic force exerted by the
external extraction electromagnet on a miniball results from the
concurrent repulsive force applied to the mesh, or extraction grid.
Containing relatively little susceptible mass, the force required
to extract drug carrier nanoparticles is higher. The distributed
ferromagnetic grains or particulate within the miniball are
advantageously given a prismatic conformation and adequate
thickness.
[2186] The mesh size of the extraction grid is selected to allow
the largest miniball to be used to pass through. How small a
miniball directed to the same impasse-jacket depends upon the
susceptibility to stretching injury of the ductus wall. The
magnetized length of the impasse-jacket must brake and arrest any
miniball that approaches. Thus, the mesh size must be matched to
the ductus wall strength and miniball diameter so that it is not so
small that excessive tractive force would be required to overcome
the shear strength of the ductus wall nor so large that extraction
would allow mesh pull-through with stretching or incision injury of
the wall--factors that can be tested, as addressed belowi in the
section entitled Testing and Tests.
[2187] The distortive straightening of a tortuous ductus to allow
the use of a longer or braced impasse-jacket to counter levering
should seldom be necessary, because, whether anomalous or varicose,
a ductus formed thus has the slack and mobility to comply with
levering without the need for end stabilizers in the form of dummy
collar or by bracing. For that reason, the need for continuous
dissection to free the ductus round and about should be
unnecessary. The articulating wires or bridges of an impasse-jacket
in a chain can span across segments that whether for mechanical,
circulatory, or neurological reasons, would best be left attached.
Once stopped by an impasse-jacket, the miniball is unable to
proceed to a second impasse-jacket.
[2188] However, when the combined strength of magnetization of a
jacket and the susceptible mass contained by a miniball is too
slight, the blood pressure or bolus will propel the miniball
through that jacket to the next. To a limited extent, and with the
understanding that the increment in flux from one jacket to the
next must be large, it is thus possible to target miniballs to
different impasse-jackets in a chain, wherein the impasse-jackets
are articulated as are stent-jackets. Accordingly, when the
impasse-jackets in a chain increase in magnetic flux in antegrade
sequence, the jackets are uniformly loaded or charged by
successively introducing miniballs of less and less magnetic
susceptibility. While not impasse-jackets, dummy-collars, or
outriggers, can stabilize a chain or braced impasse-jacket by
straddling segments not jacketed.
[2189] I15b. Structure of Impasse-Jackets
[2190] Just as all implants described herein must contain
sufficient ferrous content to allow their quick retrieval if
necessary, all impasse-jackets must support the extraction of a
miniball or miniballs with an extraction grid and by virtue of
secure attachment. Impasse-jackets are simple or compound. A simple
impasse-jacket is positioned where no need for stabilization
through bracing exists and the single jacket can accommodate the
maximum load that may be required of it. This requires firm and
strong adhesion or connection to neighboring tissue in lieu of
outriggers or dummy-collars to secure either end and is therefore
exceptional. A compound impasse-jacket consists of a magnetized
impasse-jacket at the center connected by bridging arms to one or
more unmagnetized dummy-collars, or outriggers, off to either end,
or fore and aft.
[2191] An adhesive such as cyanoacrylate cement will not persist
and must not be used to tack down the ductus off to either end of
the jacket. The use of suture or when the interval pending use of
the jacket allows, deliberately induced adhesions may serve as a
useful adjunct. Compound jackets use bridging arms to join an
individual impasse-jacket to unmagnetized dummy-collars or to other
magnetized impasse- or stent-jackets in a series or chain, in which
each jacket can differ from the others. When done for bracing, the
implant overall is elongated or extended, or not compound, then
provided with dummy-collars, and if necessary, sutured, to resist
sudden traumatic displacements that could injure the substrate
ductus in an extraction. When compounding is to allow more
miniballs to be held in the lumen, a number of magnetized
impasse-jackets are bridged together, in which case, stabilization
is inherently provided as well.
[2192] FIG. 16 shows an impasse-jacket having dummy-collars or
outrigger stabilizers 124 and therefore referred to as braced. By
securing the jacket off to either end, these prevent sudden pulling
and wrenching of the ductus during an extraction should it become
necessary. The impasse-jacket proper at the center 125 consists of
two mesh half-tubes, 126 and 127, that when closed form a complete
tube for encircling the ductus, spring-hinges 128 which fasten the
half-tubes together, and cuff-linings, 129 toward either end. Large
jackets and outriggers of braced and compound jackets, addressed in
the section to follow, can be made with a spring hinge or hinges
integrally molded, as Weatherchem, Incorporated makes in
polypropylene, for example.
[2193] The extraction grid then is made ferromagnetic by coating or
lamination. The impasse-jacket is preferably press die cut or
punched into thin gauge martensitic or precipitation carbon
hardenable nickel free stainless steel flat sheet stock that is
magnetized while still flat and before forming into a cylinder
about a mandrel. Mesh fabric that is diagonal or cross-hatched but
edged with right angular framing is not used, because when cut to
size, such material does not provide a straight or right angular
framing border. Any sharp protrusions about the edges must be
ground away and burnished to provide a smooth outer border.
Alternatively, fine gauge filter stock (screening, sieving) of like
metallurgy can be used, if necessary with each intersection in the
mesh, depending primarily on the dimensions, furnace brazed, braze
welded, or resistance welded for increased strength and
stiffness.
[2194] The material strength and gauge of the mesh, or extraction
grid, follow from the strength that the grid will need to resist
deformation in an extraction. The gauge is also a determinant in
the amount of ferrous content, hence, the strength of magnetization
the grid can sustain for retaining a miniball against the expulsive
or dislodging force of the material propelled through the lumen. In
an artery, that results from the pressure and viscosity of the
blood. When the mesh is made from wire, the intersections may be
twisted around to achieve increased magnetization and stiffness.
Whether punched or made of screening, when the mesh or gridwork is
to be overlain with a polymer incorporating ferromagnetic particles
for increased magnetization and/or heat inducibility, for example,
the bare metal mesh size must be increased to allow for the
reduction in the openings by the overlain polymer.
[2195] Whether press die cut or made from screening fabric, the
magnetized mesh is formed into a cylinder over a mandrel with the
aid of heat as necessary. If the Curie temperature is exceeded and
the strength of magnetization fails to return to its preheated
value on cooling, then the cylinder is remagnetized in the two
opposing complementary flush-fitting open-ended longitudinal mesh
half-cylinders 126 and 127 into which the cylinder is cut. Another
way to produce the extraction grid when existing mesh fabric of the
required mesh size, gauge, and stiffness is unavailable, is to
fabricate the mesh out of thin gauge iron or ferromagnetic
noncorroding steel solid round stock (wire) with good stiffness,
such as a 400 series hardened martensitic stainless.
[2196] The wire is bonded to create the bidirectional open geogrid
mesh by furnace brazing or braze or resistance welding, for
example. Each half-cylinder is hinged to its opposite as the last
step in manufacture, that is, only after brazing or welding if
involved, the addition of coatings if any, magnetization, and the
insertion of moisture barrier-coated viscoelastic polyurethane foam
cuff-linings. Bridges and outriggers are included when bonding to
yield a unitized and fracture-resistant brazement or weldment. When
the heat of bonding exceeds the Curie temperature so that
magnetization of the mesh stock while still flat is not fully
recovered on cooling, the mesh (extraction-grid) is prepared,
impasse-jacket formed, end-cuff linings (of moisture barrier-coated
viscoelastic polyurethane foam at the ends of the jacket) glued
inside, and the application of a polymer when applicable,
accomplished prior to hinging the half-tubes together and
magnetization.
[2197] The all but magnetized and hinged together half-tubes are
separately magnetized so that the external surfaces of each will be
repelled by the field of the external extraction electromagnet. The
mesh half-tubes are fastened together along their adjacent long
side edge frame by crimping the side frames together with miniature
eyeglass case type spring steel hinges of the kind that short of
closing, gently complete the closing action. The complementary mesh
half-tubes close together to form the hollow open-ended mesh tube
of the jacket. For placement on a tapered ductus where the moisture
barrier-coated viscoelastic polyurethane foam lining cannot
accommodate the taper, a mandrel of like taper is used to fabricate
the mesh half-tubes. Just as a stent-jacket, an impasse-jacket is
sized for the diastolic or quiescent diameter of the artery and
must expand with the pulse without resistance.
[2198] Peristaltic ductus are likewise sized for the quiescent
diameter. There is no special type impasse-jacket for use along the
gastrointestinal tract, which can also be fitted with a magnet-wrap
for the same purpose. Compliance without compression of the
adventitia over the uncuffed segment of the mesh is afforded
through the use of hinge springs not greater in restorative force
than yields to the pulse, and cuff-linings of moisture
barrier-coated viscoelastic polyurethane foam afford additional
flexibility in jacket diameter and pulse compliance. Increasing the
thickness of the foam cuff linings also lifts the uncuffed or
cuff-intervening portions of the mesh away from the adventitia. The
jacket should be properly matched in size to the ductus.
[2199] Tightly rolling and pressing the edges that meet when the
jacket is closed perpendicularly to the mesh or extraction grid or
fastening small tabs along the closing edges of the jacket by
crimping or with cyanoacrylate cement, for example, eliminates an
overlapping of sharp edges when the jacket is oversized. Moisture
barrier-coated viscoelastic polyurethane foam cuff linings of
adequate thickness will also prevent significant overclosure at the
edges that meet when the jacket is closed and noncompliance with
the pulse or compression of vasa and nervi vasora and perivascular
fat as a result. However, oversizing increases the distance to
susceptible matter in the lumen and may require to be compensated
for with increased strength of magnetization.
[2200] An undersized impasse-jacket is one that does not fully
close despite the clearance provided by the foam cuff linings. The
portion of the circumference where the closing edges do not meet
will lack directly radial tractive coverage for susceptible matter
in the lumen. If the strength of magnetization is high, the jacket
will exert some compressive force on the ductus, interfering with
the pulse and compressing the vasa and nervi vasora and
perivascular fat or the equivalent in a nonvascular ductus.
Impasse-jackets are not placed with a stent-jacket insertion tool
but inserted with the jacket and if present, outriggers in the open
position and placed to encircle the treatment ductus.
[2201] Moisture barrier-coated viscoelastic polyurethane foam cuff
mesh half cuff linings 129 provide:
[2202] 1. Flexibility in fitting according to lining thickness,
hence some latitude for application to ductus that are uneven in
diameter, become swollen, or have been fitted with a jacket that is
slightly oversized.
[2203] 2. A reduction in contact if not a slight separation of the
mesh from the adventia that assists to
[2204] a. Prevent compression of the outer tunic, adventitial
vasculature, innervation, and perivascular fat, and
[2205] b. Further implement compliance with the pulse even though
the jacket is sized for the diastolic (quiescent or resting)
diameter.
[2206] 3. Loop suture around mesh strands over the cuff-linings
when necessary to reduce any subjacent space without tying down the
jacket so tightly that compliance with the pulse results thus
preventing a blow under the repulsion of the extraction
electromagnet.
[2207] 4. Resistance to migration through sliding of the jacket
along the ductus.
[2208] 5. Cushioning against levering or pushing forces at the
margins of the jacket when an external electromagnet is used to
extract the trapped miniball through the lumen wall and surrounding
mesh to a safe location outside the lumen, and
[2209] 6. Reduces contact between the bridges described below and
the adventitia, thus allowing less stingent tissue acceptance
criteria to govern the use of some shape memory materials to
include polymers and alloys.
[2210] Biocompatible and implantable shape memory alloys and
polymers have attained an advanced stage of development (see, for
example, Hassani, F. A., Peh, W. Y. X., Gammad, G. G. L., Mogan, R.
P., Ng, T. K. 5., and 5 others 2017. "A 3D Printed Implantable
Device for Voiding the Bladder Using Shape Memory Alloy (SMA)
Actuators," Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
4(11):1700143; Miao, S., Zhu, W., Castro, N. J., Leng, J., and
Zhang, L. G. 2016. "Four-dimensional Printing Hierarchy Scaffolds
with Highly Biocompatible Smart Polymers for Tissue Engineering
Applications," Tissue Engineering. Part C, Methods 22(10):952-963;
van Hove, R. P., Sierevelt, I. N., van Royen, B. J., and Nolte, P.
A. 2015. "Titanium-Nitride Coating of Orthopaedic Implants: A
Review of the Literature," BioMed Research International
2015:485975; Tarni , D., Tarni , D. N., B zdoac , N., M ndril , I.,
and Vasilescu, M. 2009. "Properties and Medical Applications of
Shape Memory Alloys," Romanian Journal of Morphology and Embryology
50(1):15-21; Yeung, K. W., Poon, R. W., Chu, P. K., Chung, C. Y.,
Liu, X. Y., and 5 others 2007. "Surface Mechanical Properties,
Corrosion Resistance, and Cytocompatibility of Nitrogen
Plasma-implanted Nickel-titanium Alloys: A Comparative Study with
Commonly Used Medical Grade Materials," Journal of Biomedical
Materials Research. Part A 82(2):403-414; Es-Souni, M., Es-Souni,
M., and Fischer-Brandies, H. 2005. "Assessing the Biocompatibility
of NiTi Shape Memory Alloys Used for Medical Applications,"
Analytical and Bioanalytical Chemistry 381(3):557-567; Li, Xia,
Tang et al. below).
[2211] For relatively shallow but critical arteries such as the
external carotids, pseudoelasticity that imparts instant reversion
to the original conformation may be crucially important were the
patient to receive a direct blow to the neck, for example. Shape
memory alloys used on the external carotids do not (normally)
require midprocedural bending to be fitted. Shape memory alloys are
not preferred for more deeply situated arteries since midprocedural
bending allows such tailoring by the operator without the need to
precast the bridges with different curves. The dissolution of an
absorbable impasse- or stent-jacket leaves behind the moisture
barrier-coated viscoelastic polyurethane foam mesh as a residue,
and an absorbable braced impasse-jacket as described below also
leaves outrigger half-tube cuff linings; however, as addressed
above in the section entitled Summary Description of the Invention,
this residue will be far short of the quantity that could act as a
carcinogen.
[2212] Exceptionally, radiation shielded stent-jackets for use with
magnetically targeted drug or irradiating drug carrier-bound
nanoparticles are not absorbable. Following fabrication and before
any additional coating and magnetization, the magnetic field of the
mesh half-tubes can often be increased in intensity if coated or
plated with a ferromagnetic material such as nickel-iron (Li, X.
P., Seet, H. L., Zhao, Z. J., and Kong, Y. K. 2005. "Development of
High Permeability Nanocrystalline Ferromagnetic Materials by Pulse
Plating," Journal of Metastable and Nanocrystalline Materials
23:163-166) amorphous Fe.sub.75Si.sub.15B.sub.10 powder (Parker, F.
T., Spada, F. E., Berkowitz, A. E., Vecchio, K. S., Lavernia, E.
J., and Rodriguez, R. 2001. "Thick Amorphous Ferromagnetic Coatings
via Thermal Spraying of Spark-eroded Powder," Materials Letters
48(3-4):184-187). Thereafter, the impasse-jacket can be further
encapsulated, irradiated, or drug elution coated.
[2213] A polymer coating itself can incorporate ferromagnetic
nanoparticles (Srikanth, H., Poddar, P., and Gass, J. 2005.
"Materials Processing and Tunable Magnetism in Polymer
Nanocomposites," in Gupta, M., Srivatsan, T. S., Lim, C. Y. H., and
Varin, R. A. (eds.), Processing and Fabrication of Advanced
Materials XIII, Volume 1, Singapore: Stallion Press, pages
367-376). A more strongly magnetizable polymer coating incorporates
neodymium iron boron lanthanoid, for example. Especially if the
polymer and impasse-jacket it coats are absorbable, and as safe
practice in general, the lanthanoid is encapsulated for chemical
isolation when eventually or unexpectedly released. When applied to
enclose the vessel, the impasse-jacket should fit no more snugly
than is necessary to prevent its migration by sliding along the
ductus.
[2214] I15c. Braced, Compound, and Chain Impasse-Jackets
[2215] Moderately repelled by the extraction electromagnet,
lengthening the impasse-jacket adds moments of resistance to
suppress levering or margin-repulsion against the substrate ductus
and/or subjacent tissue during an extraction. Lengthwise extension
of the impasse-jacket that would distortively straighten a ductus
which is normally tortuous or that would require extended
continuous dissection to free the ductus round and about or from a
subjacent attachment or adhesion, is avoided by straddling such
segments. To these ends, the central magnetized stopping jacket is
rigidly bridged margin to margin to nonmagnetized dummy jackets, or
outriggers, placed in encircling relation to the segments situated
beyond the unused or unusable intervening segments.
[2216] All impasse-jackets with outriggers are braced but referred
to as chained only when connected to more than one outrigger at
either end. The outriggers are the same in construction as the
impasse-jacket proper but serving as stabilizers, are usually
shorter. Outriggers can serve not only for antilevering
stabilization but also as inlets and outlets for direct connection
to an Ommaya-like reservoir or infusion set cannula at the body
surface with catheter leading to the outrigger for direct delivery
to the lumen of a drug, magnetic drug carrier ferrofluid-bound
drug, or other therapeutic substance. Typically, the drug is
infused through the upstream or entry outrigger, and if needed, a
reversal agent through the distal segment of the jacket or
downstream outrigger.
[2217] Unless the patient is alone and mentally impaired,
infrequent dosing is by syringe. Otherwise, dosing is by means of a
portable pump. Impasse-jackets are not chained as are stent-jackets
wherein each substent is functional; to span over or straddle a
segment that flexes, only one magnetized or functional
impasse-jacket is used, outriggers when present provided as
stabilizers. A braced impasse-jacket usually has the form of a
unitized threesome, but more extended, can be a fivesome, for
example. The appelation `chain` still describes such an interrupted
and concatenated conformation. Bridging utilizes a center
magnetized impasse-jacket of maximum length for the anatomy.
[2218] Single-piece bridges rigidly connect the stopping jacket to
the outrigger fore and aft, and if a second outrigger is included,
the first to the second outrigger. An impasse-jacket in a chain
otherwise comprised of stent-jackets is stabilized at each side by
connection to the adjacent jackets, which may in turn be stabilized
by means of side-straps, or if an end-stent, then an end-tie.
Impasse-jackets can also be stabilized or rendered additionally
resistant migration to migration by end-ties as are used with
stent-jackets. In ordinary nonabsorbable braced impasse-jackets,
bridges 130 consist of nonmagnetic stainless steel bridging arm 132
and edge-rims, or mesh half-tube edge-rims, 131.
[2219] Where beneficial, reduced mass without significant loss in
biocompatibility, strength, noncorrodability, nonsusceptibility to
the magnetic field, and permanence, the bridge pieces are cast from
titanium alloy (see, for example, Lukomska-Symanska, M.,
Brzezinski, P. M., Zieli ski, A., and Sokolowski, J. 2010. "The
Connective Tissue Response to Ti, NiCr and AgPd Alloys," Folia
Histochemica et Cytobiologica 30;48(3):339-345; Lautenschlager, E.
P. and Monaghan, P. 1993. "Titanium and Titanium Alloys as Dental
Materials," International Dental Journal 43(3):245-253). Such
alloys and presumably those exhibiting pseudoelasticity appear to
be improved in biocompatibility when coated with a diamond-like
carbon coating (Li, Q., Xia, Y. Y., Tang, J. C., Wang, R. Y., Bei,
C. Y., and Zeng, Y. 2010. "In Vitro and In Vivo Biocompatibility
Investigation of Diamond-like Carbon Coated Nickel-titanium Shape
Memory Alloy," Artificial Cells, Blood Substitutes, and
Immobilization Biotechnology 39(3): 137-142).
[2220] Alternately, a nonmagnetic stainless steel can be used. In
FIG. 16, the braced impasse-jacket is assembled in two steps, the
first consisting of connecting the ordinarily three half-tubes
representing one half or one side of the completed cylindrical
triple jacket together, and the second step of joining together two
of these half triple cylinders into a spring loaded openable
cylinder. Assembly thus allows uniform magnetization of the two
halves in relation to the field of an extraction electromagnet that
may be needed before fastening the two triple jacket half cylinders
together. The triple mesh half cylinders are fastened together by
connecting the approximating (neighboring, facing) end-edges or
margins of the mesh half cylinders together by means of
bridge-pieces or bridge-braces 130.
[2221] Fusion together of the mesh half-tubes to the semicircular
arms 131 of brace bridges 130 is by furnace brazing or resistance
welding. Outriggers 124 are constructed as is the impasse-jacket
proper 125 at the center, to include end-margin cuff linings of
moisture barrier-coated viscoelastic polyurethane foam 129, but are
usually shorter. Now a unitized weldment, the three half-tubes
representing each half or side of the completed cylindrical triple
jacket is magnetized so that the outer surface of the completed
impasse-jacket will have the same polarity as the extraction
electromagnet.
[2222] So that the impasse-jacket and two outriggers will open and
close along the same line, bridge arms 131 and the mesh half
cylinder to either side are aligned. Once the three two mesh triple
half cylinders have been magnetized with the same polarity, each is
fastened to the other by crimping on spring-hinges 128 along one
longitudinal meeting edge of each as defined by one end of the
brace arms 131. Absorbable braced impasse-jackets are likewise made
unitized of absorbable suture and tissue scaffold materials
specified, for example, in the section above entitled Absorbable
Stent-jacket Expansion Insert Materials with Relatively Short
Breakdown Times.
[2223] Since the absolute distance separating the impasse-jacket
from the outriggers is usually small enough, the chain-guard can be
inserted as a unit with center jacket and outriggers in open
position through a single access incision at the body surface and
most likely without the need to lengthen the incision. All of the
elements of an absorbable braced impasse-jacket, except for the
moisture barrier-coated viscoelastic polyurethane foam cuff-linings
of the center magnetized jacket and the complete foam linings of
the outriggers, are absorbable, to include the mesh sheeting, rims
and rim-connecting braces, which are made from one or more of the
polymers specified above for the magnetizable steel mesh coatings
of steel mesh jackets and in other sections herein. Following
absorption, the moisture barrier-coated viscoelastic polyurethane
foam cuff-linings remain as an innocuous residue, as explained
above in the section entitled Summary Description of the
Invention.
[2224] I15d. Cooperative Use of Impasse-Jackets in Pairs and
Gradient Arrays
[2225] The use of magnetized ductus-intramural implants to define a
segment of a ductus for delivery of a drug or drugs is the same as
described in this section for impasse-jackets, patch-magnets and
magnet-wraps, the latter limited to large ductus. Any of these
arranged along a ductus can be used to define a segment for
treatment by attracting a drug from the passing lumen contents.
Segment and organ targeting, addressed above in sections entitled
Field of the Invention and Concept of the Impasse-jacket among
others, are discussed in relation to jackets and impasse-jackets in
particular, because these afford more utility where the need for a
reversal agent exists. An entry jacket at the inlet, usually
arterial, allows targeting an organ with a drug.
[2226] If any outflow of the drug must be prevented, then an
exit-jacket is placed at the outlet, usually venous to release a
counteractant. The drug sequencing and targeting means addressed
herein, and the use of exit-jackets in particular are intended to
prompt the development of new pharmaceuticals. Other arrangements
analogous to Halbach cylinders where the conformation of the field
rather than high field strength is sought may be contemplated (see,
for example, Coey, M. and Weaire, D. 1998. "Magnets, Markets, and
Magic Cylinders" Industrial Physicist, September 34-36; Zhu, Z. Q.
2000. "Powder Alignment System for Anisotropic Bonded NdFeB Halbach
Cylinders" Institute of Electrical and Electronics Engineers
Transactions on Magnetics 36(5) :3349-3352).
[2227] Usually too strongly magnetized, miniballs and stays and
arrays thereof used to attract susceptible matter from the lumen
are seldom integrable into a formation of miniballs or stays used
for stenting. Magnetized stays are automatically oriented upon
introduction; magnetized miniballs are delivered with the substrate
ductus while temporarily encircled within a susceptible jacket
which causes the miniballs to self-orient in the cytoplasm at the
trajectory terminus. The use of magnetized miniballs, stays, and
impasse-jackets for targeted chemotherapy or neoadjuvant
chemotherapy preparatory to surgical resection through the
application of magnetic force is addressed above in the section
entitled Drug-releasing and Irradiating Miniballs, Stays, and
Ferrofluids.
[2228] In terms of existing medication, the use of evenly spaced
miniballs or stays along a ductus, arranged in order of increasing
strength of magnetization in the antegrade direction, or of two or
more impasse-jackets used thus to achieve selective segmental
concentration of a drug. Usually the carrier will likewise include
particles that are graduated in magnetic susceptibility. When
passing such an array, the drug, a statin, or
3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase
inhibitor, for example, is drawn into the diseased segment. The
carrier-bound drug is preferably administered orally in the form of
a capsule but otherwise self-administered through a subcutaneously
implanted infusion port placed to free the patient from the
clinic.
[2229] Although concentrated for the treatment segment, a portion
of the statin dose that might pass the array will be innocuous. The
addition of an exit jacket to release a reversal agent or
counteractant, however, introduces the possibility of using
substances or concentrations previously considered too toxic for
therapeutic use. The following section addresses direct lines to
jacket whether magnetized. Most anticancer chemotherapeutics in
common use are cytotoxic or vesicant (Verboom, M. C., Ouwerkerk,
J., Steeghs, N., Lutjeboer, J., Martijn Kerst, J., and 4 others
2017. "Central Venous Access Related Adverse Events after
Trabectedin Infusions in Soft Tissue Sarcoma Patients; Experience
and Management in a Nationwide Multi-center Study," Clinical
Sarcoma Research 7:2; Theman, T. A., Hartzell, T. L., Sinha, I.,
Polson, K., Morgan, J., and 3 others 2009. "Recognition of a New
Chemotherapeutic Vesicant: Trabectedin (Ecteinascidin-743)
Extravasation with Skin and Soft Tissue Damage," Journal of
Clinical Oncology 27(33):e198-200; Ener, R. A., Meglathery, S. B.,
and Styler, M. 2004. "Extravasation of Systemic Hemato-oncological
Therapies," Annals of Oncology 15(6):858-862). The statin or other
drug may or may not prevail against a background of the same or an
adjuvant or counteracting drug introduced into the general
circulation.
[2230] For example, atherosclerosis a systemic disease (see, for
example, Toutouzas, K., Drakopoulou, M., Mitropoulos, J., Tsiamis,
E., Vaina, S., and 4 others 2006. "Elevated Plaque Temperature in
Non-culprit de Novo Atheromatous Lesions of Patients with Acute
Coronary Syndromes," Journal of the American College of Cardiology
47(2):301-306), statins can evoke unwanted side effects as
specified below, but have been recognized as exerting beneficial
effects locally and not just when delivered through the bloodstream
by inhibiting cholesterol biosynthesis in the liver that would
otherwise be released into the systemic circulation (see, for
example, Nissen, S. E., Tuzcu, E. M., Schoenhagen, P., Crowe, T.,
Sasiela, W. J., and 5 others 2005. "Statin Therapy, LDL
Cholesterol, C-reactive Protein, and Coronary Artery Disease," New
England Journal of Medicine 352(1):29-38; Erl, W. 2005.
"Statin-induced Vascular Smooth Muscle Cell Apoptosis: A Possible
Role in the Prevention of Restenosis?," Current Drug Targets.
Cardiovascular and Haematological Disorders 5(2):135-144).
[2231] Substantially restricting exposure to a statin to only
diseased tissue may allow individuals with adverse side effects to
the drug when circulated at greater than a threshold concentration
to avoid the unwanted effect. When the disease is systemic but
acutely affects only circumscribed tissue, systemic delivery of the
drug can be reduced while local delivery is raised to a level that
if circulated would induce the side effects if not prove toxic
(see, for example, McCarey, D. W., McInnes, I. B., Madhok, R.,
Hampson, R., Scherbakov, O., Ford, I., Capell, H. A., and Sattar,
N. 2004. "Trial of Atorvastatin in Rheumatoid Arthritis (TARA):
Double-blind, Randomised Placebo-controlled Trial," Lancet
363(9426):2015-2021; Klareskog, L. and Hamsten, A. 2004. "Statins
in Rheumatoid Arthritis--Two Birds with One Stone?," Lancet
363(9426):2011-2012).
[2232] Drugs can also be concentrated for uptake by impasse-jacket
straddled organs, for example. The cooperative use of
impasse-jackets or stent-jackets, which can also be used to stent
the drug the inlet or drug release segment and outlet or drug
counteractant release segment, in pairs and higher combinations
extends drug-targeting capability to definable lengths of ductus.
The segment for treatment is defined by a start-of-segment entry
jacket and an end-of-segment exit-jacket. Stent-jackets,
patch-magnets, magnet-jackets, and magnetized stays and miniballs
can be incorporated into a succession of carrier particle
attracters or retainers along a ductus for dual or multistage
drug-targeting.
[2233] In paired or plural use, impasse-jackets are positioned to
mark off and thus define a treatment segment or stretch of a ductus
using at least one jacket at the start and at least one at the end
to define and treat the segment. Longer segments generally call for
an entry jacket followed, according to the local need, by
intervening jackets that are uniformly or nonuniformly spaced and
contribute an additional complement of the same or a different drug
before the exit jacket is reached. For drugs that can be directly
counteracted (reversed, inactivated, neutralized) safely by another
agent used as a direct chemical counteractant to be released from
the exit jacket with or without heat, jackets can be paired to
define the starting and ending levels along the lumen therebyto
target only the segment selected for treatment.
[2234] Sequencing impasse-jackets with or without stent-jackets is
addressed above in the section entitled System Implant Magnetic
Drug and Radiation Targeting and Concept of the Impasse-jacket and
below in the section Alternative Procedure to the Use of Expansion
Inserts. Heating can be by direct contact at the treatment site,
which is not tied to the clinic or by the placement of miniballs,
stays, impasse-jackets, and stent-jackets in an alternating
magnetic field which is. Since all of the implants will include
magnetically susceptible content, differential heating if necessary
is limited to elevated temperatures. When released by spontaneous
dissolution, ingestion, or self-infusion through an implanted
portal of a second agent, and/or by direct heating where a specific
jacket need not or can be targeted or discriminated, the
counteracting or neutralization of a drug released from a holding
jacket or otherwise approaching from upstream is freed from the
clinic.
[2235] Ionizing radiation is effective at breaking some chemical
bonds, but only at levels much higher than can be generated within
a tiny circumductal (circumvascular) collar. In additive
interactive application, a drug released upon dissolution of or
elution from a miniball held by a holding jacket upstream can be
irradiated or combined with another drug farther downstream as the
drug passes a radioactive or another drug-emitting miniball held in
a downstream holding jacket. Whether the miniballs and holding
jacket are unheated or heated from without and/or within, the
holding jackets can suspend miniballs in the lumen that release
drugs which will be absorbed through the adluminal layers
separating the luminal from the implanted miniballs or stays
thereby to produce the desired therapeutic effect by
endoluminal/ductus-intramural interaction.
[2236] This could, but usually would not pertain to the component
unit holding jackets of the same compound impasse-jacket with only
a small interval between them. A compound impasse-jacket wherein
consecutive individual impasse-jackets are used to retain a larger
number of miniballs to increase the dose, or to isolate different
type therapeutic substances, such as irradiating, medicating, or
different containing drugs, is referred to as a composite or mixed
impasse-jacket and is understood to be compound or paired, as
addressed below. Such a jacket allows the differential extraction
of the miniball or miniballs assigned to each jacket. The
drug-targeting means described herein include the direct
implantation of miniballs and stays, magnetic drug-targeting, and
segment definition through suspension in the lumen of miniballs or
ferrofluid-bound drugs by means of impasse-jackets, for
example.
[2237] For drugs for which there is a counteractant that chemically
acts directly on the drug rather than pharmacokinetically or
metabolically (through drug-drug or drug-food interaction primarily
in the liver) to yield innocuous products, the dose can be reduced
or effectively stopped at the end of the segment; by positioning
the holding jacket with the drug upstream from the holding jacket
with its counteractant, only the intervening segment is medicated.
In this way, a segment of almost any extent along a ductus, and not
just a focal point, can be defined and targeted for treatment.
[2238] For experimental purposes, the ability to target a
prescribed segment of an artery in vivo for exposure to a drug
allows distinguishing between local and systemic or metabolic
effects of the drug. Statins are among the most widely prescribed
drugs, in iself indicating strong benefits and low incidence of
adverse side effects; however, the size of the population also
means that many patients (diabetics, pregnant and breastfeeding
women) may be denied these benefits. One example of value in the
ability to target a chosen segment of a ductus for medication with
a much higher dose than could be allowed in the circulation as a
general concept is that of statin drugs.
[2239] The ability to restrict exposure to high concentrations of
statins in the renal arteries of diabetics to avert the myopathy or
rhabdomyolysis associated with high doses in the circulation while
preserving renal function (see, for example, Paulsen, L.,
Matthesen, S. K., Bech, J. N., Starklint, J., and Pedersen, E. B.
2010. "Acute Effects of Atorvastatin on Glomerular Filtration Rate,
Tubular Function, Blood Pressure, and Vasoactive Hormones in
Patients with Type 2 Diabetes," Journal of Clinical Pharmacology
50(7):816-822; Romayne Kurukulasuriya, L., Athappan, G., Saab, G.,
Whaley Connell, A., and Sowers, J. R. 2007. "HMG CoA Reductase
Inhibitors and Renoprotection: The Weight of the Evidence,"
Therapeutic Advances in Cardiovascular Disease 1(1):49-59) warrants
study.
[2240] While disputed for a population with established coronary
artery disease rather than for the prevention of acute cardiac
events in those with incipient dyslipidemia and only for the
systemic dosage levels allowed, (see, for example, Robinson, J. G.,
Smith, B., Maheshwari, N., and Schrott, H. 2005. "Pleiotropic
Effects of Statins: Benefit Beyond Cholesterol Reduction? A
Meta-regression Analysis," Journal of the American College of
Cardiology 46(10):1855-1862), statins are at least tentatively
accepted by some as able to ameliorate atheromatous inflammation
through mechanisms not necessarily tied to a reduction serum
cholesterol (see, for example, Jones, P. H. and Farmer, J. A. 2008.
"Adjunctive Interventions in Myocardial Infarction: The Role of
Statin Therapy," Current Atherosclerosis Reports 10(2):142-148;
Devaraj, S., Rogers, J., and Jialal, I. 2007. "Statins and
Biomarkers of Inflammation," Current Atherosclerosis Reports
9(1):33-41; de Lorenzo, F., Feher, M., Martin, J., Collot-Teixeira,
S., Dotsenko, O., and McGregor, J. L. 2006. "Statin
Therapy--Evidence Beyond Lipid Lowering Contributing to Plaque
Stability," Current Medicinal Chemistry 13(28):3385-3393;
Rutishauser, J. 2006. "The Role of Statins in Clinical
Medicine--LDL--Cholesterol Lowering and Beyond," Swiss Medical
Weekly 136(3-4):41-49; Bellosta, S., Ferri, N., Arnaboldi, L.,
Bernini, F., Paoletti, R., and Corsini, A. 2000. "Pleiotropic
Effects of Statins in Atherosclerosis and Diabetes," Diabetes Care
23 Supplement 2:B72-B78).
[2241] Holding jackets allow a statin drug, for example, in a
concentration that if circulated would be myotoxic and in a
diabetic could prove renotoxic, to be released at the start, and if
desired, stopped at the end of a certain length (stretch, segment)
of an artery that is lesioned or especially lesioned. Assuming its
reduction in inflammation is not due entirely to the lowering in
serum cholesterol but involves a direct mechanism or mechanisms as
well (Glynn, R. J., Koenig, W., Nordestgaard, B. G., Shepherd, J.,
and Ridker, P. M. 2010. "Rosuvastatin for Primary Prevention in
Older Persons with Elevated C-reactive Protein and Low to Average
Low-density Lipoprotein Cholesterol Levels: Exploratory Analysis of
a Randomized Trial," Annals of Internal Medicine 152(8):488-496,
W174; Ridker, P. M., Danielson, E., Fonseca, F. A., Genest, J.,
Gotto, A. M. Jr., and 9 others; JUPITER Study Group 2008.
"Rosuvastatin to Prevent Vascular Events in Men and Women with
Elevated C-reactive Protein," New England Journal of Medicine
359(21):2195-2207, available at
http://www.nejm.org/doi/full/10.1056/NEJMoa0807646#t=article Top;
Furberg, C. D. 1999. "Natural Statins and Stroke Risk," Circulation
99(2):185-188, available at
http://circ.ahajournals.org/cgi/content/full/99/2/185), local
release substantially confined to a defined segment would allow
exposure to a statin drug, for example, with a local concentration
far higher than could be prescribed for systemic administration but
with an overall dose still minute and required over a shorter
term.
[2242] Also, as addressed above in the section entitled Circulating
Drug Blocking and Drug Interaction Avoidance, targeting a statin,
notably, simvastatin, to a limited segment of an arterial lumen
wall with a calcium channel blocker such as diltiazem or verapamil
in the circulation or itself targeted for the coronary arteries,
for example, should eliminate the myotoxic much less rhabdomyolytic
consequences of the two when circulated together. The direct and
circumscribed targeting of a segment of an artery with a statin
avoids binding the statin in the gut by cholestyramine or
colestipol, for example, as when both are administered orally.
Drugs such as carnitine and coenzyme Q10 (ubiquinone,
ubidicarenone) used systemically to counteract statin overdose
resulting in myopathy, for example, tend to be large and continued
over time. As pertains to almost any adverse drug-drug interaction
dependent upon drugs where both are introduced into the
bloodstream, so long as one does not require to be metabolized by
the liver, that drug can be delivered directly to the lesion thus
substantially if not entirely eliminating it from the circulation
and therewith eliminating the interaction as well. With respect to
statins, for example, to counter the elevated serum cholesterol and
triglycerides that result as a side effect of a protease inhibitor
given to treat hepatitis C or human immunodeficiency virus, the
protease inhibitor is often co-administered with a statin for
systemic circulation.
[2243] However, some statins used thus are associated with
drug-drug interaction that results in a manyfold increase in statin
exposure that can induce myopathy and even rhabdomyolysis leading
to significant kidney damage or death ("FDA Drug Safety
Communication: Interactions between Certain HIV or Hepatitis C
Drugs and Cholesterol-lowering Statin Drugs Can Increase the Risk
of Muscle Injury," available at
http://www.fda.gov/Drugs/DrugSafety/ucm293877.htm). Magnetized
miniballs, stays, arrays thereof, and impasse-jackets make it
possible to directly target atheromas with any statin
contraindicated for co-circulation in any concentration. Statins
specified as contraindicated for co-circulation with these protease
inhibitors include atorvastatin (Lipitor.RTM., Torvast.RTM.,
Cardipill-LS.RTM.), lovastatin (Mevacor.RTM., Altocor.RTM.,
Altoprev.RTM., Lipistat), rosuvastatin (Crestor.RTM.), and
simvastatin (Zocor.RTM., Lipex.RTM.).
[2244] Accordingly, using the means described herein allows the
concentrated application of any disallowed statin directly at and
substantially limited to the athermomatous segment treated at the
same time that one of the statins approved for co-administration,
specifically, pitavastatin (Livalo.RTM., Pitava.RTM.) or
pravastatin (Pravachol.RTM., Selektine.RTM., Lipostat.RTM.), is
circulated with the protease inhibitor to counter an elevation in
cholesterol and triglycerides levels without a concomitant surge in
statin exposure as an unwanted side effect. Using a holding jacket
or holding jackets, dosing can be continued using consecutively
time-released miniballs in the number required. Using an entry
impasse-jacket, an especially diseased and/or occluded segment of a
ductus can be differentially treated.
[2245] For example, a statin drug in much higher concentration than
could be prescribed systemically can be released locally at the
start of the segment and either allowed to lose concentration by
continued flow with the circulation, or, with the addition of an
exit-jacket, can be removed as the exit-jacket is passed, the exit
jacket dose usually adjusted to counteract the dose released at the
entry-jacket. Furthermore, the use of impasse-jackets that
incorporate extracorporeally energizable internal heating as
addressed below makes it possible to heat the lumen wall and the
medication releasing miniball or miniballs held by the entry jacket
for accelerated dissolution and uptake, and if appropriate, to
substantially extinguish these effects on passing the exit jacket
of the pair.
[2246] Adverse sequelae have been associated with the metabolic
mechanism that interferes with cholesterol synthesis (possibly as
the result of overdosing), to include myositis and myalgia (see,
for example, Joy, T. R. and Hegele, R. A. 2009. "Narrative Review:
Statin-related Myopathy," Annals of Internal Medicine
150(12):858-868), possible liver damage in patients otherwise
compromised (see, for example, Liu, Y., Cheng, Z., Ding, L., Fang,
F., Cheng, K. A., Fang, Q., and Shi, G. P. 2010.
"Atorvastatin-induced Acute Elevation of Hepatic Enzymes and the
Absence of Cross-toxicity of Pravastatin," International Journal of
Clinical Pharmacology and Therapeutics 48(12):798-802), as well as
other adverse effects (see, for example, Kiortsis, D. N.,
Filippatos, T. D., Mikhailidis, D. P., Elisaf, M. S., and
Liberopoulos, E. N. 2007. "Statin-associated Adverse Effects Beyond
Muscle and Liver Toxicity," Atherosclerosis 195(1):7-16).
[2247] Targeting a statin to minimize pancreatic exposure may also
reduce the 9 percent risk, primarily in older adults, of inducing
type 2 diabetes (Sattar, N., Preiss, D., Murray, H. M., Welsh, P.,
and 29 collaborators 2010. "Statins and Risk of Incident Diabetes:
A Collaborative Meta-analysis of Randomised Statin Trials," Lancet
375(9716):735-742). The benefit of statins as attriibutable to a
reduction in plasma cholesterol has been disputed and even claimed
to be harmful (see, for example, Ravnskov, U., Allen, C., Atrens,
D., Enig, M. G., Groves, B., Kauffman, J. M., Kroneld, R., and 6
others 2002. "Studies of Dietary Fat and Heart Disease," Science
295(5559):1464-1466, available at
http://www.ravnskov.nu/cholskept.links.responsetoGrundy.htm;
Morrell, S. F. and Enig, M. G. 2000. "The Skinny on Fats," at
http://www.westonaprice.org/know-your-fats/526-skinny-on-fats.html).
[2248] The inducement of liver damage in the absence of existing
disease has not been conclusively determined (see, for example,
Lewis, J. H. 2012. "Clinical Perspective: Statins and the
Liver--Harmful or Helpful?," Digestive Diseases and Sciences May
12; Bergmann, O. M., Kristjansson, G., Jonasson, J. G., and
Bjornsson, E. S. 2011. "Jaundice Due to Suspected Statin
Hepatotoxicity: A Case Series," Digestive Diseases and Sciences
November 11; Bader, T. 2010. "The Myth of Statin-induced
Hepatotoxicity," American Journal of Gastroenterology
105(5):978-980; Rajaram, M. 2009. "Hepatitis, Rhabdomyolysis and
Multi-organ Failure Resulting from Statin Use," British Medical
Journal Case Reports February 2009), but statin-associated
hepatotoxicity as aggravating existing disease (see, for example,
Calderon, R. M., Cubeddu, L. X., Goldberg, R. B., and Schiff, E. R.
2010. "Statins in the Treatment of Dyslipidemia in the Presence of
Elevated Liver Aminotransferase Levels: A Therapeutic Dilemma,"
Mayo Clinic Proceedings 85(4):349-356; Russo, M. W., Scobey, M.,
and Bonkovsky, H. L. 2009. "Drug-induced Liver Injury Associated
with Statins," Seminars in Liver Disease 29(4):412-22) is seldom
disputed for specific preexisting conditions (see, for example,
Madhoun, M. F. and Bader, T. 2010. "Statins Improve ALT Values in
Chronic Hepatitis C Patients with Abnormal Values," Digestive
Diseases and Sciences 55(3):870-871; Sorokin, A., Brown, J. L., and
Thompson, P. D. 2007. "Primary Biliary Cirrhosis, Hyperlipidemia,
and Atherosclerotic Risk: A Systematic Review," Atherosclerosis
194(2):293-299; Lowyck, I. and Fevery, J. 2007. "Statins in
Hepatobiliary Diseases: Effects, Indications and Risks," Acta
Gastroenterologica Belgica 70(4):381-388).
[2249] Administration of a statin in this targeted manner dispels
the long-standing and unresolved concerns for teratogenic risk
(see, for example, Taguchi, N., Rubin, E. T., Hosokawa, A., Choi,
J., Ying, A. Y., Moretti, M. E., Koren, G., and Ito, S. 2008.
"Prenatal Exposure to HMG-CoA Reductase Inhibitors: Effects on
Fetal and Neonatal Outcomes," Reproductive Toxicology
26(2):175-177; Petersen, E. E., Mitchell, A. A., Carey, J. C.,
Werler, M. M., Louik, C., and Rasmussen, S. A. 2008. "Maternal
Exposure to Statins and Risk for Birth Defects: A Case-Series
Approach," American Journal of Medical Genetics. Part A
146A(20):2701-2705; Kazmin, A., Garcia-Bournissen, F., and Koren,
G. 2007. "Risks of Statin Use during Pregnancy: A Systematic
Review," Journal of Obstetrics and Gynaecology Canada
29(11):906-908).
[2250] However, entry jackets on the carotids and exit-jackets on
the jugulars as addressed above in the sction entitled Concept of
the Impasse-jacket, should allow the prenatal use of thalidomide,
other sedative-hypnotics, and any other kind of drug that must be
kept from reaching the placenta. While an invasive procedure to
place the trap array for the sole purpose of allowing the use of a
statin will normally be discounted, the ability to use many other
drugs in selected patients will justify the procedure. Also, since
the drug is eliminated without being metabolized, adverse drug
interactions are substantially eliminated, allowing drugs to be
used together that otherwise would interact as to pose a risk.
[2251] There is no need to avoid prescribing antibiotics,
antimycotics, antidepressants, immunosuppressants, colchicine
(Sarullo, F. M., Americo, L., Di Franco, A., and Di Pasquale, P.
2010. "Rhabdomyolysis Induced by Co-administration of Fluvastatin
(Lescol.RTM.) and Colchicine," Monaldi Archives for Chest Disease
74(3):147-149), fenofibrate (Buyukhatipoglu, H., Sezen, Y.,
Guntekin, U., Kirhan, I., and Dag, O. F. 2010. "Acute Renal Failure
with the Combined Use of Rosuvastatin and Fenofibrate, Renal
Failure 32(5):633-635), and gemfibrozil (Jones, P. H. and Davidson,
M. H. 2005. "Reporting Rate of Rhabdomyolysis with
Fenofibrate+Statin Versus Gemfibrozil+Any Statin," American Journal
of Cardiology 95(1):120-122), for example, or advising the patient
to avoid grapefruit or grapefruit juice, which impede statin
metabolism resulting in higher plasma levels and can result in
muscle damage, liver damage, and death.
[2252] If for some unforeseeable reason a statin counteractant is
desired, the choice indicated is no more
3-hydroxy-3-methylglutaryl-coenzyme A reductase (Brown, M. S.,
Dana, S. E., Dietschy, J. M., and Siperstein, M. D. 1973.
"3-Hydroxy-3-methylglutaryl Coenzyme A Reductase. Solubilization
and Purification of a Cold-sensitive Microsomal Enzyme," Journal of
Biological Chemistry 248(13):4731-4738, available at
http://www.jbc.org/content/248/13/4731.full.pdf+html) than could be
necessary to take up the reductase inhibitor. Similarly,
pharmaceuticals such as enzymes that act upon a substrate
substance, as does an inhibitor on a reductase, the substrate
itself may serve as the reversal agent. Where a background of
systemically distributed statin is wanted for the systemic
condition, an impasse-jacket allows supplementing the systemic dose
over an especially affected segment with no exit jacket used to
counteract or neutralize the statin released locally.
[2253] 5-fluorouracil formulated for delivery to an entry jacket or
jacket-array along the gastrointestinal tract for magnetically
targeted chemotherapy of the surrounding wall, for example, can be
counteracted through the release from an exit jacket of
Vistonuridine.RTM. (Wellstat Therapeutics Corporation). Leucovorin
(folinic acid) alone and with glucarpidase (carboxypeptidase),
thymidine, and folinic acid act counter to methotrexate. The number
of reversal agents suitable for release from an exit jacket should
increase over time. This sectioning off of the ductus (usually a
blood vessel) into segments to define treatment zones for
differential dosing, druging, or other chemical treatment can be
continued over much of the length of the ductus.
[2254] When necessary, a nonabsorbable jacket is used to allow for
the reinjection of medication or radiation miniballs at intervals
beyond the life expectancy of an absorbable jacket. A peripheral
artery, for example, can be marked off in segments for differential
medication and/or dosing of each segment, using jackets spaced at
intervals that span past lesions such as atheromatous or as
otherwise desired. If necessary, these jackets are nonabsorbable.
Re-charging or re-dosing of any type holding jacket is currently by
conventional hypodermic injection upstream from the holding jacket
and used to increase, continue, or chemically disable the drug.
Oral administration should become possible in the near future.
Continued delivery is also possible by placing drug-eluting
miniballs with consecutive release times at the entry level.
[2255] I15e. Direct Lines from the Body Surface to and from Impasse
and Other Type Jackets
[2256] Without means for creating safe, nonleaking, harmless, and
smooth continuity between catheteric and native lumina to connect
fluid and electrical lines, a standard to which indwelling
catheters do not remotely rise, and tissue surface fluid and
electrical line connectors likewise noninjurious, to provide a
fully implanted automatic disorder response system capable of
operating for many years is impossible. Direct piping to and from a
tubular anatomical structure, or ductus, through a catheteric line
entered from outside the body through a portal implanted at the
body surface to a ductus side-entry or impasse-jacket for
connection to a ductus or to a nonjacketing side-entry connector
fastened to the surface of tissue or an organ can be conceived of
as expanding upon the concept of a laparoenterostomy or a
jejunostomy, for example, where a tube is surgically connected to
the gut to provide nutrients when the digestive tract is obstructed
proximad-, meaning above, or drainage when the bowel is obstructed
below, or distad.
[2257] Copending applications 2016/0051806 and 20170197028 describe
and illustrate the drug feedlines, connectors, and body surface
ports used to effect connections far the directly pipe targeted
delivery of drugs and other therapeutic substances. This drug
targeting by means of direct piping applies to the jackets and
wraps described herein as well as applications 2016/0051806 and
20170197028 An exemplary arm or channel of control in a
hierarchically organized automatic disorder response system
emplaced to treat comorbid conditions is addressed in section XX
below and FIG. 107, with the organization and componentry addressed
in section XXI and FIG. 108. Delivery of the drug, radionuclide, or
other therapeutic substance to an impasse-jacket is preferably
passive, that is, by injection, infusion, or ingestion followed by
normal passage through the lumen. The need for direct delivery is
satisfied by infusion through the surface port and into the
feedline, thence to the target tissue whether a ductus, which is
unsuitable for administration on an ongoing basis.
[2258] To treat interactive (trans-syndromal) and noninteractive
(trans-nosological) conditions in comorbidity, a small port at the
body surface, usually in the pectoral region with multiple openings
for different drugs to admit drugs into subdermally positioned
reservoirs for dispensing to any of a number of ductus side-entry
jackets responsive to signals received from sensors processed by a
prescription program driven microcontroller is administered by a
fully implanted automatic adaptive hierarchical ambulatory
prosthetic disorder response control system. Such a system, which
can incorporate the telemetric transmission of data to the clinic
(see, for example, Ferguson, J. E. and Redish, A. D. 2011, Op
cit.), is described in copending application 20160051806, Ser. No.
14/121,365 entitled Ductus Side-entry Jackets and Prosthetic
Disorder Response Systems and below in the sections entitled
Exemplary Channel of Control in a Fully Implanted Ambulatory
Adaptive Hierarchical Control System for Automatic Response to a
Comorbid Condition and Fully Implanted Ambulatory Adaptive
Hierarchical Control System for Automatic Response to a Comorbid
Condition. Direct piping to each of a number of jackets also allows
different segments of the same ductus to receive different drugs,
doses, or both.
[2259] The direct metered delivery of each drug to its target
jacket eliminates the potential vagaries of passive delivery where
control is limited. Direct lines to and from magnetized
impasse-jackets and other jackets from an infusion set cannula or
cannulae at the body surface for connecting a syringe or pump serve
to draw medication into the wall surrounding the lumen. By
comparison, nonmagnetized jackets allow the direct delivery of
therapeutic substances and the withdrawal of samples of luminal
contents for analysis with little if any penetration into the
surrounding wall. When not in use, the portal is sprayed with
disinfectant and covered with a single use flesh colored bandage
with pressure sensitive adhesive backing when dry. Driving the
prescribed dose of each therapeutic substance ahead of a column of
water assures that no portion of the dose is left within or can
clog the line.
[2260] The syringe barrel refill cartridge or infusion pump
delivers a measured volume of the therapeutic substance followed by
a measured volume of water. Different substances can be brought by
dilution with water, for example, to the same viscosity. In the
clinic, the use of transparent tubing and contrast can assist to
confirm that the thereapuetic substance has been administered. When
possible, the portal at the body surface are situated at a level
higher than that of the jackets. An impasse-jacket and/or dummy
collar with side-access (side-entry, side inlet, side-outlet)
connector is used when the need for continuous or frequent dosing
with the same or different drugs is known or likely to ensue.
Aspiration to provide samples for analysis at any jacketed level
along the ductus is practicable as well.
[2261] The direct piping of a lavage solution to an upstream jacket
whether of the impasse-, stent-, magnet, or clasp-jacket type
allows irrigation or samples to be drawn from any jacket
downstream. Nonmagnetized jackets and dummy-collars can also be
used thus. The dummy-collar braced downstream to an impasse-jacket
can thus serve as a take-off for samples to confirm drug uptake
within or release at the impasse-jacket. The inlet, and if a
reversal agent is necessary, an outlet jacket can be unmagnetized.
An impasse-jacket, its dummy collar or collars, or both can be
provided with side-access lines for direct injection from a syringe
through an Ommaya-like reservoir or infusion by a portable
miniature pump through an infusion set cannula at the body surface
of substances such as drug carrier nanoparticles, for example.
[2262] An independent direct line feed to each of several
impasse-jackets overcomes the problem of selectively targeting each
jacket with a different substance or substances, as well as
simplifies higher rate intermittent or continuous administration of
drugs to the segments, organ, or gland the impasse-jackets bound
and define. A side-access connector can be incorporated into any
impasse-jacket and/or dummy collar or outrigger, but unless needed,
such use is uneconomic. Because it must be harvested, properly
stitched in place, may stenose, shrink, occlude, increases the risk
of infection, and makes attachment to the synthetic components more
complicated, an autologous vein graft is not preferred for use as
an impasse-jacket side-access line.
[2263] These steps introduce additional complications and risks and
significantly protract a procedure. Many ductus treatable with one
or more impasse-jackets are small, necessitating the use of
microsurgical techniques. When directed not to the ductus but
rather to an impasse-jacket or dummy collar, incorporation of a
polymeric catheter connector in the jacket or collar eliminates the
need for midprocedural steps. Instead, the jacket with connector is
preassembled, insertion then consisting only of placing the jacket
about the ductus. However, when connection of a side-access line is
from the body surface to the ductus itself up- or downstream from
the jacket, an autologous graft is preferred. The side-access
connector consists of a length of transparent polymeric tubing only
so long as as extends from the internal surface of the lumen to a
length beyond the outer tunic sufficient to connect a line.
[2264] The inner or or ductus-ward rim about the luminal or adaxial
end of the catheter connector tube is sharp and has a luminal-end
valve that consists of a resilient polymer slit membrane which
opens to the lumen only when drawn by a retrograde vacuum or pushed
by antegrade pressure greater than that of the blood or other
pressure in the lumen. So that a point of thrombogenic turbulence
will not be created along the internal surface of the lumen wall,
the sharp distal tip or rim is level with, not protrusive beyond,
the slit membrane valve, and both are level with the internal
surface of the ductus once the ductus wall is cut through and the
wall plug extracted. On manufacture, the slit membrane is bonded
within the end of the connector tube so that it will not tear loose
under the antegrade, or forward, and retrograde, or aspirative,
pressure to which the valve will be subjected.
[2265] The pressure will be imposed by a syringe or pump connected
tothe connection point at the surface of the body, such as an
Ommaya-like reservoir or infusion set cannula and patch. A round
hole to admit the connector tube is cut through the extraction grid
and foam lining, and a flange surrounding the hole having a neck
extending perpendicularly outward to afford a larger surface area
for bonding to the tube is bonded to the extraction grid about the
hole but not to the connector. The connector tube, and the inner or
ductus-ward tip of the connector tube slid through the hole so that
its distal or ductus-ward tip is brought flush level with the
internal surface of the foam lining. Until placement, the connector
tube fits through the hole in the flange, extraction grid, and foam
lining through which it passes only so tightly as prevents it from
falling out, and remains slidable therethrough.
[2266] Impasse-jacket compliance or expansion and contraction as
the pulse passes is provided by the foam lining, and in excess of
that permitted by the foam lining, by the spring-loaded hinge
joining the halves so that these can open and close. Since the slit
membrane valve is flush or level to the internal surface of the
vessel or intima, while the foam lining and hinge are outside the
adventitia, the point where the line leading from the connection
point at the body surface enters the jacket can be placed anywhere
but where the halves part. On placement, the outer surface of the
ductus is wetted with contrast, the impasse-jacket or outrigger
placed about the ductus, the adaxial end of the connector tube
pushed flush against the outer surface of the ductus, and an
aspiration line connected to the abaxial or radially outward end of
the connector tube.
[2267] The adaxial end of the connector tube is slid through the
flange into contact with the outer surface of the ductus, and the
aspiration line used to cause the sharp rim of the connector tube,
which protrudes forward when the resilient membrane is drawn
backward, to incise into the wall of the ductus. The force of
aspiration is raised until the plug cut into the ductus wall is
drawn out through the membrane slit, the contrast and transparence
of the connection tube allowing this process to be observed. This
method for insertion of the supply or aspiration line through the
side of the ductus with simultaneous plug extraction and line
insertion allows application to an artery with little bleeding or
hemodynamic interruption, and to the gut with little if any leakage
of septic matter, and since it avoids the need to interrupt
perfusion through clamping, ligature, or serrenoeuding, as well as
allows contact at limited to the treatment point with single-sided
approach, can be applied to a coronary or a carotid artery, for
example.
[2268] The inner or adaxial end of the connector tube is then slid
through the flange so as to be flush level with the internal
surface of the lumen wall, and the flange, having been bonded to
the extraction grid when manufactured, is then bonded to the
connection tube. The outer or abaxial end of the side-connector now
extends out of the side of the impasse-jacket to a length no
greater than allows a body surface infusion set cannula connection
catheter to be securely connected to it. The use of a quickly
setting cyanoacrylate cement to bond the connection tube to the
internal surface of the neck of the surrounding flange once its
inner end has been brought flush to the internal surface of the
lumen allows connection to the catheter supply line that will lead
to the infusion set cannula and patch or Ommaya-like reservoir type
connection at the body surface in a single procedure.
[2269] Whether or not connected to a catheteric supply and
aspiration line during the procedure, the protruding end of the
side connector has rounded and smoothed edges. When not connected,
the surrounding tissue is additionally protected by placing tape
over the exposed end until needed. Referring now to FIG. 16, it
should now be clear that either end collar 124 can be accessed from
the body surface through a side-access connector, so that if not
completely taken up during the intervening segment and leaving a
residue that could cause adverse side effects if carried beyond the
diseased segment, a drug or other therapeutic substance introduced
through the upstream collar can be neutralized or reversed by a
reversal agent released from the downstream collar.
[2270] To allow an additional substance or substances to be
delivered directly to it, impasse-jacket proper 125 can also be
connected to the body surface. The use of plural side-access
connectors to or from collars 124 or jacket 125 is plainly possible
but not likely to be necessary. Magnetizing the adaxial end or
segment by using a ferromagnetic flange or laminating or coating
the connection tube with a polymer layer containing magnetized
inclusions allows a magnetic nanoparticle carrier bound drug be
held abaxially or short of the slit membrane outside of the ductus
lumen, then forced through the slit membrane when the pressure
imposed by the syringe or pump is sufficient to force it open. If
prepositioned thus to avert a future accident but never needed, the
prestored drug or other substance can be drawn for laboratory
analysis by aspiration at the body surface conector.
[2271] Magnetic drug carrier particles that are ferro cobound, or
indissolubly and/or temperature-independently bound to the
medicinal component, are drawn toward the source of the magnetic
force, and since the impasse-jacket surrounds the ductus, the
particles are drawn into the wall surrounding the lumen. By
comparison, drug carrier particles that are ferro-bound are
released to flow upstream, the magnetic force drawing only the
ferromagnetic component of the conjoined ferrous and medicinal
particles into the wall. To treat a discrete organ such as a
kidney, the entry impasse-jacket is placed along the renal artery,
the ferro-bound drug freed to pass into the parenchyma. If a
residue is to be eliminated, then a jacket to release a reversal
agent is placed along the renal vein.
[2272] Access and clearance sufficient to place these jackets
requires dissection through the renal fat pad, artery, and, special
care given to not transect the first branches of the artery and
vein, which support the adrenal gland. Unlike a healthy artery free
of atheromatous, dissecting, or other lesions, wherein the
constituents of the blood, such as leukocytes and blood fats flow
along the surrounding wall as it were a conduit with few such
constituents drawn therein, in the kidney, flow is intrinsically to
the parenchymal tissue, which may be diseased. In a diseased
artery, however, encirclement with a magnetized jacket serves to
draw the ferrobound drug into the diseased wall. With disease of
the cortex, however, patch-magnets attached to the outer fibrous
capsule, or with respect to organs more generally, the involucrum,
will actively draw the drug outward and into the diseased
tissue.
[2273] A substance piped from a syringe can be adjusted in
temperature before delivery, one from a portable pump warmed by
heating at or by the pump, and/or the impasse-jacket can be
remotely warmed by placing the patient in a radiofrequency
alternated magnetic field, as addressed in section X2c below
entitled Stereotactic Arrest and Extraction of a Dangerously
Circulating, Mispositioned, or Embolizing Miniball, among others.
Stent-, impasse-, magnet-, and clasp-jackets large enough to
incorporate conductive wire such as nichrome can be heated by wire
connection at the body surface connector. Innumerable combinations
of medicinal fluids additionally allow carrier release or
neutralizing dissolution with continuation downstream.
[2274] The potential for iron overburden through accumulation of
the carrier is addressed above in the section entitled Field of the
Invention and should not be associated with the risk of
transfusional hemosiderosis where the iron content is far higher.
Iron overload might arise with a small patient in whom drug
carrier-bound drugs are continually distributed to multiple
jackets. In this event, monitoring and treatment by deferoxamine
injection Desferal.RTM., phlebotomy (see, for example, The Merck
Manual of Diagnosis and Therapy, 18th Edition, pages 1132-1133)
and/or chelation therapy (see, for example, Harrison's Priciples of
Internal Medicine, 16th Edition, page 600) constitute the standard
of care response measures.
[2275] Fully implanted ambulatory adaptive hierarchical control
systems for automatic response to comorbid conditions and an
exemplary channel of control in an ambulatory adaptive hierarchical
control system for automatic response to comorbid impairment are
described in copending application Ser. No. 14/121,365 published as
20160051806 entitled Ductus Side-entry Jackets and Prosthetic
Disorder Response Systems and below in the sections entitled Fully
Implanted Ambulatory Adaptive Hierarchical Control Systems for
Automatic Response to Comorbid Conditions and An Exemplary Channel
of Control in an Ambulatory Adaptive Hierarchical Control System
for Automatic Response to Comorbid Impairment.
[2276] I15f. Single and Plural Circuit Pumping through Direct Lines
to Jackets
[2277] For placement along the vascular tree, a syringe or portable
infusion pump delivers the substance to the impasse-jacket or
dummy-collar. Depending upon the form of bond between the carrier
and the drug, the jacket actively draws the magnetic drug carrier
with the drug from the blood into the lumen wall or only the
carrier is drawn to the jacket and the drug released to continue
downstream. The strength of magnetization along the jacket,
distance separating the carriers from the jacket, susceptibility of
the carrier, and direction and pressure of the bloodstream thus set
the direction, rate, and take-up of the carrier with the drug. If
the drug is released to proceed upstream, then carrier separation
rate must be considered. Drugs bound with the carrier to obtain
both types of targeting can be included in the same or consecutive
suspensions.
[2278] With conditions that present separated segments which
require like treatment such as does regional enteritis and
atheromatous plaques, multiple portals are not implanted at the
body surface; rather, a wider diameter trunk coming off the surface
portal branches to each jacket. The diameter of each branch allows
differential distribution of a therapeutic substance to each
segment. Physiological factors such as the blood pressure and pulse
rate are not ordinarily manipulated for this purpose, distribution
along the lumen wall left to the magnetic field strength at a given
level relative to carrier distance and susceptibility and
concentration at a given level. However concentrated, when the drug
carrier is uniformly attached to the drug in one-for-one relation,
the drug carriers and concentration are inherently matched, so that
the rate and level of extraction from the passing blood is
relatively constant on passing through an impasse-jacket of given
magnetization gradient.
[2279] The point of entry of the delivery catheter, which can serve
as a supply or aspiration line, into the jacket is ordinarily
toward the upstream (entry, proximal) margin of the jacket.
Hypothetically, this one-for-one relation should allow a given
combination of a jacket and drug carrier with any drug and the
complete uptake of a drug to be limited to a jacketed segment
without continuation through the general circulation. The
preferability to eliminate an unwanted residue, if any, from
continuing downstream can be satisfied by placing a downstream
impasse-jacket or a jacket with a magnetized, rather than a dummy
exit collar with piped reversal agent, or a magnetized downstream
outrigger to release a reversal agent.
[2280] Furthermore, because the risk of clogging the jacket
disallows more than a moderate mass of a drug to be delivered at a
given rate, and dilution within the circulation is high. These
factors mean that the need for a reversal agent is exceptional. If
advisable, a reversal agent can be piped through a second line
entering the impasse-jacket toward its downstream end or the
downstream outrigger or dummy-collar of the jacket. Similarly, the
drug or radionuclide carrier can be delivered to its upstream
dummy-collar or the upstream segment of the jacket. Ductus that can
be briefly clamped to define a certain segment can be lavaged over
that segment by introduction of plain water, antiseptic, or
antifungal solution through a jacket whether magnetized at either
end and its removal at the opposite end of the segment.
[2281] I16. Stent-Jacket Insertion Tools
[2282] I16a. Insertion Tool Structure
[2283] Stent-jacket insertion tools (stent-jacket openers,
stent-jacket applicators, stent-jacket placement tools,
stent-jacket implant tools, base-tube retractors, side-slit
expanders, side-slit retractors, side-slot retractors, side-slit
expanders, etc.), such as those shown in FIGS. 16 thru 19 are made
of nonmagnetic metal or plastic and provided in a range of sizes to
expand stent-jackets of different diameters and thicknesses for
placement about (in surrounding relation to) vessels or ducts at
different depths. The terms `tube retractor` and `tube expander`
already in use for unrelated devices, terms such as `base-tube
(slit) expander` or `base-tube slit-edge retractor` are necessary
to distinguish such a stent-jacket base-tube expansion and
placement device. Stent-jacket insertion tools are used to pry open
the elastic jacket to encircle the ductus.
[2284] Impasse-jackets are inserted through the access incision
while open, an insertion tool then limited to assisting in making
adjustments following initial placement. Stent-jacket and stay
nsertion tools include side-clips for attaching an endoscope,
laser, aspiration line, or other cabled ancillary device. When a
separate incision is necessary to access the outside of a tubular
structure that is inaccessible from outside the body, the
minimization of trauma requires that the incision be small and that
the component to be inserted be practically manipulable through the
incision. Small joint arthroscopic tools are available, but not
suited to opening the stent-jacket through the incision.
Accordingly, special tools are provided to minimize the size of the
access wound needed to apply a stent-jacket.
[2285] Compared to the length of the incision needed to suture
prosthetic rings at intervals about the trachea, for example, that
needed to insert and place a stent-jacket is small. To minimize
procedural and general anesthetic time as well as trauma, even
larger stent-jackets, chain-stents, and chain-guards (braced
guards) must insert through minimal entry portals and do so
readily. Stent-jacket insertion tools must be nonmagnetic, hence
made, for example, of austenitic stainless steel, such as 18-8,
304, or 316 amenable of hardening in smaller thicknesses. Due to
the need for absolute and dependable stiffness in the arms of these
tools, the unacceptability of the parts coming apart in use, and
the need to avoid any protrusions by joints or tightening screws,
for example, the use of adapters to fit over the arms of existing
surgical instruments is discounted.
[2286] For use in a robot, the `fingers` of the claw hand are
configured as are the arms of the insertion tool as described
below. Such tools are made to conform to the many dimensional
requirements of base-tubes having different thicknesses and the
need for handles of a length adequate to access deeper locations
within the body. To allow passage through as small an incision as
possible, the tools are long-handled and narrow but with burnished
edges and in a gauge unlikely to injure anatomy that must be moved
aside to reach to target ductus. While any number of complex
linkages, ratchets, or pulleys could be incorporated into such a
tube slit expansion device, any of which could further be made
adjustable for use with stent-jackets over a range of sizes, for
the least expense and greatest dependability, the use of simple
tools is preferred.
[2287] That stent-jacket insertion tools can be provided with
handles suitable for use with a robot is considered obvious. That
shown in FIG. 17 is essentially a small spring-tongs similar to a
Finsen-type retractor for shallow placement, but with continuously
flat and curved spatula-shaped blades 10 as in a Deaver retractor.
Blades 10 are reversed or everted so that the major convex surfaces
face outwards and the distal ends of the scoop-shaped blades are
recurved or bent around to produce unciform, or hooking, ends 13 as
seen in profile. Hooking ends 13 engage the edges of slit 9 in
base-tube 5 as seen in FIG. 5. The minor convex surfaces of hooking
ends 13 face medially inward toward one another and thus reversely
relative to the balance of the blades 10.
[2288] In any spring type tongs or tweezers-configured stent-jacket
insertion tool, rotary joints to facilitate access to the exterior
of the ductus to be treated through a keyhole incision can be
provided. These joints, which are placed just short of the distal
point where the blades begin to curve outward at the working end on
each side of the handle, allow the operator to forcibly pivot the
blades together to either side perpendicularly to the direction of
blade opposition. The rotary friction joints consist of a tight
rivet with beryllium copper or austenitic stainless steel wave
spring washer, for example. For a stent-jacket of given diameter,
insertion tools are made in different lengths. Making hooking ends
13 somewhat rounded and open facilitates use of a single tool with
base-tubes of different thickness without resistance to release of
the side-slit or side-slot when the base-tube is to be
released.
[2289] In most instances, however, there will not be sufficient
space behind the ductus to allow disengagement thus, so that the
tool must be be gently pushed forward and slid off one or the other
side edge. To prevent the hook-ends from catching into the moisture
barrier-coated viscoelastic polyurethane foam lining will usually
necessitate pre-wetting the lining with a lubricant such as ACS
Microslide.RTM., Medtronic Enhance.RTM., Bard Pro/Pel.RTM. or
Hydro/Pel.RTM., Cordis SLX.RTM., or Rotaglide..RTM. This action is
carried out with minimal injury to the peripheral blood and nervous
supplies foremost; one reason to use a compound stent is the
reduced distance to the side edges to disengage the insertion tool
from any one sub-stent. That shown in FIG. 16 is a springs tong
type for deeper lying ductus.
[2290] The tools are made of heavy gauge spring steel, which may be
plated for corrosion resistance. Stent-jacket insertion tools for
jacketing vessels, for example, are generally 2 to 3 millimeters in
side-on thickness or width expanding to 4 to 5 millimeters across
the hook ends. Those for expanding larger stent-jackets are
proportional in thickness relative to overall dimensions. To avoid
being caught along when slid over the edges of the stent-jacket
side-slit during application to the ductus, the edges of the
insertion tool hooking ends are rounded, and the hooking ends of
smaller tools are coated with polytetrafluoroethylene. To prevent
the snagging of neighboring anatomical structures, the outer edges
are rounded as well. However, the incorporation of rollers to line
the hook is not preferred as unnecessarily difficult to manufacture
and costly.
[2291] The conformation of hooking tips 13 must allow free
disengagement from the free edges of the stent-jacket side-slit by
a quick forward movement. Nonmagnetic polytetrafluoroethyene coated
hooking tips 13 retain the width of the blades 10 proximal or
leading up to these. The handles or arms 11 are configured and
united below at a junction 12, and since the tools would normally
be made of one continuous piece of metal, this would usually be at
least one but here shown as two sharp bends where the handles of
the two sides join to enhance the outward springiness or
restorative force that acts to expand the base-tube slit when not
forcibly closed by squeezing the sides together.
[2292] Finger rests, or widened portions along handles 11 for the
thumb and index finger to pinch the arms together could be added,
but have not, because at uniformly five millimeters in width for a
tool of average length, the lever handles are wide enough that the
tool will not rotate between the fingers, especially when covered
with gloves of neoprene, synthetic polyisoprene latex, or latex. To
incorporate sliding finger rests that would allow taking advantage
of the optimal moments of force in the surgical layout involved
would be more a hindrance than aid, the operator intuitively moving
to the position affording the best leverage. The working or blade
portions distal to the crook in the handles can be joined to the
straight portions of the handles by a rivet to create a swivel
joint (not shown) that allows the angle between the straight
portions and the working ends to be varied.
[2293] The rivets are tightened enough to prevent the ends from
unintentional rotation. The stent-jacket placement tool shown in
FIG. 18 is a scissors-tongs rather than a spring-tongs or
tweezer-type configured embodiment for shallow placement that is
similar to a Weitlaner type retractor just as the tweezers type is
similar to a Finsen-type retractor, except that it is designed to
pull in only two rather than three directions. The continuous
flattened spoon or scoop-shaped retractor blades 14 are the same as
those of the tongs-type retraction tool described immediately
above. In any scissors or pliers-configured stent-jacket insertion
tool, rotary joints to allow the blades to pivot perpendicularly to
the direction of blade opposition consist of a tight rivet on each
side of the handle positioned distal to the main rotary joint that
joins and allows rotation of the handles.
[2294] The handles 15, made as single parts, are reversely bent so
that closing the finger holes 16 opens rather than closes the end
hooks 17. The scissors-tongs can be urged either open or closed by
means of torsion or leaf springs, as is well known in the
scissors-making industry. While the stent-jacket insertion tool
shown in FIGS. 18 and 19 are not shown in an edge-on view, tools
for jacketing vessels, for example, are generally 2 to 3
millimeters in side-on thickness or width expanding to 4 to 5
millimeters across the hook ends, while those for expanding larger
stent-jackets are proportional in thickness relative to overall
dimensions.
[2295] As with the tweezers type tool of FIGS. 16 and 17, to
minimize the length of the incision necessary to access the vessel
or duct from the outside for placement of the stent-jacket, the
working ends distal to the handles can be joined to the handles by
rotary joints or rivets 158 in FIG. 18 to create swivel joints that
allow the angle between the handles and the hook-like tips 17 for
engaging the free edges of the base-tube side-slit or slot to be
varied when a probe is used to prod the base-tube to the angle
required. The rivets are tightened enough to prevent the ends from
other than intentional rotation. An embodiment configured as shown
in FIG. 18 or as a pistol grip, for example, can be made with a
ring that allows use of the index finger to adjust the angle of the
working ends (not shown). The finger-ring retracts or pushes
forward a rod connected to lever arms joined to the working ends
distal to the swivel joints to change the working angle. The design
of surgical retractors make such configurations familiar.
[2296] I16b. Use of the Stent-Jacket Insertion Tool
[2297] In use, the stent-jacket is placed on the insertion tool so
that the free edges of the stent-jacket are held within the
recurved distal working hook tips 17 of the tool and the side-slit
is directed forward. In preliminary testing prior to application,
depending upon its pliancy and length, the stent-jacket when pulled
open at its midpoint will open sufficiently for placement along its
entire length or only over the segment proximal to the hooking ends
of the insertion tool. Tho expedite the release of the hook ends 13
from the edges of the stent-jacket, the end of the tool can be
wetted with any suitable lubricant such as Medtronic
Enhance.RTM..
[2298] If expansion is limited in length, then the ease with which
the hooking tips slide along the cut edges of the stent-jacket
side-slit or side-slot with one end of the stent-jacket fixed in
position is checked prior to insertion, and if,
polytetrafluoroethylene coating notwithstanding, the tool resists
being slid along the pulled apart edges of the side-slit, the
working ends of the insertion tool are wetted with a lubricant
(antiadherent, glidant) such as those specified above in the
preceding section entitled Sectional Extraluminal Stents, Segmented
and Articulated or Chain-stents. The stent-jacket can be expanded
(pulled open) for placement either prior to entry or upon reaching
the target ductus.
[2299] Depending upon the angle of approach, length, the need to
clear neighboring structures, and resilience of the stent-jacket,
the end-hooks of the insertion tool are used to pull open the
stent-jacket at its center or close to one or the other of its
ends, ideally, prior to introduction through the entry wound. The
stent-jacket is introduced through a small incision (microincision,
`keyhole,` bandaid; or laparoscopic incision) close to if not
directly overlying the location for placement. The width of the
entry wound required depends upon the size of the stent-jacket,
whether it is pulled open prior to entry, and whether it can be
inserted parallel to the handles of the insertion tool. Entry with
the stent-jacket pulled open and parallel to the handles of the
insertion tool allows passage through a smaller incision.
[2300] Whether the stent-jacket has been expanded prior to
insertion, entry can be parallel to surface of the body, with one
side of the stent-jacket placed through the entry wound at a time.
Since the insertion tool hook-tips are rotatable, a sterile wooden
stick probe can be used along the path to the target ductus to
angle the stent-jacket as necessary to avoid neighboring
structures. When the side-slit is proximal, facing, parallel to the
target ductus, and the stent-jacket can be sufficiently expanded to
apply it without further effort, it is pushed forward to encircle
the substrate ductus. When the stent-jacket is longer or more
pliant, use of the stent-jacket insertion tool can be made
difficult by the tendency of the base-tube to contract over too
short a length to the sides of the tool working tips.
[2301] More often a probe held against the closed end or one of the
bar magnets will be needed to stabilize or push the stent-jacket so
that the insertion tool hook ends slide along the free edges of the
base-tube side-slit to progressively pull the stent-jacket open
along its entire length for encirclement of the target ductus. That
is, the insertion tool is slid along the free edges of the
stent-jacket side-slit, or the free edges of the stent-jacket
side-slit are slid through the hook-ends of the insertion tool, or
these movements are used in combination as the anatomy and forces
involved dictate.
[2302] II. Clasp-Magnets
[2303] II1. Subcutaneous, Suprapleural, and Other Organ-Attachable
Clasp- or Patch-Magnets
[2304] Clasp- or patch-magnets for exerting attractive force over
greater distances mount discrete magnets on clasps for fastening to
tissue. This is the type shown in FIGS. 25 and 26. For use over
shorter distances, the clasp itself is magnetized and
biocompatibility encapsulated for chemical isolation, various
polymers, noble metals, and nonmagnetic stainless steels available
for this purpose. Clasp-magnets are made as unobtrusive and with
rounded edges to be as nonabrading to surrounding tissue as
possible, hence, flatly conformed with rounded edges.
[2305] Clasp-magnets for attachment to tissue that includes small
vessels and nerves or which diseased, for example, must not be
compressed, are lined with viscoelastic polyurethane `memory` foam
as are the magnet-wrap shown in FIG. 21 and clasp-wrap shown in
FIG. 24. Patch-magnets fastened to the outer layers of a discrete
organ such as a kidney or the spleen can be used to draw a drug,
and/or other therapeutic substances irradiating or not from the
bloodstream into the parenchyma. For this purpose, biocompatibly
encapsulated neodymium iron boron is strongly magnetized in a
patch-magnet of the maximum dimensions as avoids significant
encroachment on the surrounding tissue. Drug delivery by
minispheres and nanoparticles is already well developed.
[2306] Magnets to remain in place indefinitely are internally
undivided, whereas those to disintegrate as part of an absorbable
implant consist of magnetized particles, ordinarily containing
neodymium iron boron, bonded together but separately encapsulated
for chemical isolation following disintegration with clasps made of
absorbable material such as those specified in the section below
entitled Stent-jacket Expansion Inserts, which enumerates
substances that spontaneously disintegrate over a shorter period
through hydrolytic and enzymatic action and long-term materials to
be broken down by lithotripsy. Fastened at any level along the
digestive tract the heart, or other organ, for example, by
introducing the prongs or clasps through the outer serosal or
pericardial layer, a clasp-magnet will trap and hold miniballs that
incorporate sufficient ferrous or magnetically susceptible matter
passing through the lumen.
[2307] While more quickly placed than an impasse-jacket to perform
this function, the clasp-magnet is not configured to allow
extraction with the aid of a powerful external electromagnet. In
such use, the clasp-magnet or magnets can detain miniballs that are
absorbable or contain a drug precursor released when exposed to a
chemical activator or heat, for example, with others downstream
holding miniballs that release a reversal agent when similarly
activated, as addressed above in the section entitled Concept of
the impasse-jacket and below in the section entitled Miniball and
Ferrojluid-impassable Jackets, or Impasse-jackets, among
others.
[2308] Clasp-magnets are used to effect a structural adjustment
such as ductus patenting, ductus deflection, or tissue deflection
in combination with any other implant described herein and with
drug carrier bound nanoparticles ordinarily delivered in a
ferrofluid to attract the drug into the substrate tissue. Used
structurally, clasp-magnets placed circumtracheally to treat
tracheal collapse can be situated suprapleurally or subcutaneously.
Used for drug targeting, clasp-magnets are attached to the outside
of an organ to draw drug carrier nanoparticles from the blood or
other contents passing through a lumen, such as along the
gastrointestinal tract.
[2309] These drugs are typically antineoplastic, and whether
antimycotic (mycetogenetic, antifungal, fungicidal), antibacterial
(bactericidal), antiprotozoal, antiviral (viricidal), antihelmintic
(anthelminthic, anthelmintic, vermicide, verifuge), or
broad-spectrum antibiotic or anti-infective, where the infection is
localized to or concentrated in the organ, whether a background
systemic dose, often reducible responsive to such targeting, is
also administered. While muscle fascia is ill-defined from the
subjacent epimycial fascia, so that pinching skeletal muscle fascia
does not, for example, lift the fascia away from the underlying
muscle, the integument is substantially free to move in relation to
underlying skeletal muscle.
[2310] That is, the integument is loosely attached as to easily
slide over the underlying muscle, which is stable in average
position relative to the skeleton. Therefore, a thin permanent
magnet with rounded corners that project at the top and sides
attached to the muscle fascia moves with the muscle, the internal
surface of the integument freely sliding over it. Like
magnet-wraps, clasp-magnets are generally at a distance from the
implants to be attracted, and therefore incorporate discrete
permanent, rather than intrinsic, quasi-intrinsic, or laminated
magnets, as described above in the section entitled Types of
stent-jacket, which are, however, no less applicable in closer
placement. The use of a moisture barrier-coated viscoelastic
polyurethane foam lining in a patch-magnet depends upon the
presence of microvasculature or nervelets on the surface of the
substrate tissue.
[2311] A primary application of clasp- or patch-magnets is
attachment to the surface of an organ to attract drug carrier
nanoparticles from the blood, thereby overcoming the need to find
substances that are naturally drawn to the organ as is iodine to
the thyroid gland, for example. Natural attraction has the
advantage of being noninvasive; however, the practical application
of this approach depends upon the development of substances
spontaneously drawn to the target organ. This use of clasp-magnets
is addressed above in the section entitled System Implant Magnetic
Drug and Radiation Targeting. In FIGS. 25 and 26, a patch-magnet is
shown mounting a tiny permanent magnet, that is, as extrinsically
magnetized, rather than in the form of a clasp made of
intrinsically magnetized material.
[2312] While clasp-magnets can support a lesser strength of
magnetization for use in stent-jackets, for example, where the
magnetic energy product, or magnetic field strength per unit mass,
of neodymium iron boron permanent magnets serves miniaturization
for unobtrusiveness, here this material is used as much to produce
a strong field to attract over a distance or to draw magnetically
susceptible drug carrier nanoparticles from the blood or other
luminal contents. Clasp-magnets as most of the other system
components described herein can be provided in a form sufficiently
disintegrable to be described as absorbable where dissolution of a
chemically isolated encapsulated residue poses no problem.
[2313] The stent-jacket shown in FIGS. 1 thru 6 and 13 and the
magnet-clarity wrap shown in FIG. 21 are likewise shown with
permanent magnets mounted not only for for illustrative but because
the aligned domains within an integral permanent magnet allow for
greater field strength essential to attract the susceptible implant
over a distance. In actuality and in particular, when less field
strength is required, intrinsically and quasi-intrinsically
magnetized components, as defined above in the section entitled
Types of stent-jacket, which are compact and free of protrusions,
are used. Thus, the magnet-wrap shown in FIG. 21 might incorporate
magnetized beads woven onto the backing, for example. Unless the
permanent magnets are very small to include encapsulation for
chemical isolation, clasp-magnets and magnet-wraps using these are
not made to be absorbed.
[2314] Clasp-magnets for use with adjacent tissue can be produced
in laminated form with an intrinsically or quasi-intrinsically
magnetized layer, radiation shield, or absorbable radiation shield,
as addressed above in the section entitled Noninvasive dissolution
on demand of absorbable stent-jackets, base-tubes, radiation
shields, and miniballs. The dissolution of any absorbable implant
or part thereof can be used to release a drug or other therapeutic
substance. Whether suspension is by means of patch-magnets,
implants, or jackets, to avoid placing disruptive forces on the
anterior (ventral) wall of the esophagus, the strength of the
magnetic pull should be no greater than is necessary to prevent the
dorsal membrane from being drawn down by the tidal flow of
respiration.
[2315] A collapsed bronchial ceiling can thus be suspended using
subcutaneous clasp-magnets, or patch-magnets, situated over the
affected membrane to draw implanted miniballs or stays out of the
lumen. In dogs, with collapsed bronchi, the insertion of
ductus-intramural implants and patch-magnets involves little trauma
and eliminates the need for endoluminal stents that must be
reexamined and cleaned or replaced often. To accomplish the same
end surgically requires a throracotomy. The magnets must be
positioned so that the esophagus limits the distance that the
tracheal ceiling can be drawn, and lung tissue limits the distance
that the bronchi can be drawn and selected for a pulling force that
effects suspension without imposing unnecessary force on these
limiting tissues.
[2316] In such application, the magnets are attached to the outside
of the skeletal muscle or to pleura above the bronchi to run
parallel with the underlying miniball implants.Since the
subcutaneous implants are more readily interchanged to ascertain
the best strength magnet to use at points superjacent to the
miniballs, the internal implants are generally placed first and the
magnets placed thereafter. Since the miniballs are implanted with
the patient supine, and have little mass, collapse is not
aggrevated during the interval until the magnets have been placed.
Unless there has been asphyxiation, it should be possible to
perform the implantation in one an initial procedure, and placement
of the magnets in another. By pressing the magnets down to the
level these would occupy once attached, this can be accomplished
before incision.
[2317] Just before closing, the area surrounding the prongs is
treated with a long-effect local anesthetic, such as lidocaine
(lignocaine; Xylocaine.RTM.). Prongs 36 are preferably made of
elgiloycobalt-chromium-nickel steel and perforated or deep-textured
for tissue infiltration and wetted with phosphorylcholine, for
example, to suppress an adverse tissue response. Retention of the
clasp-magnet is mechanical and without the aid of an adhesive.
While the opposition of the prongs toward either end of the
clasp-magnet, or patch-magnet, makes dislodgement improbable, the
prongs can also be coated with a solder that encourages tissue
infiltration, the solder denatured by warming the patch-magnet once
placed the efficacy of using a laser to denature the solder
contingent upon the number and position of the prongs.
[2318] Because it immediately surrounds the affected ductus and
inherently but flexibly limits wall excursion, when not otherwise
contraindicated, the use of subadventitially implanted miniballs
with a stent-jacket is preferred to alternative methods such as the
use of a miniball jacket with stent-jacket, minimagnet with a
miniball jacket or with implanted miniballs, or subcutaneous or
superpleural magnets. Where a stent-jacket cannot be used, such
placement can afford a suitable location for peripheral magnets to
act upon more deeply implanted miniballs. Subcutaneous placement
also allows retrieval with relatively little difficulty, but may
require preventing the patient from lying beside some objects made
of ferrous metal, such as a filing cabinet.
[2319] Referring now to FIGS. 24 and 25, shown is a patch-magnet or
clasp-magnet that incorporates disk magnet 34 for attachment to the
muscle fascia or pleura. The magnet 34 is bonded to subjacent
strips 35, preferably made of an austenitic stainless steel such as
18-8, 304, or 316, cold-worked to full hardness to induce
shape-memory or restorative force so as to act as a small
nonmagnetic leaf-spring. These strips 35 run beneath and in
tangential relation to the magnet 34 along its undersides and are
cambered, with the magnet surmounting the center convexity on the
upper surfaces. In manufacture, the die cut includes perforations
in parts to contact tissue, especially the clasps, which typically
penetrate the substrate tissue to a depth of 3-4 millimeters, which
is intended to allow tissue inflitration and integration for
increased retentive tenacity.
[2320] Since these elements will be completely encapsulated and
isolated within a bioinert plastic jacket, the adhesive used to
bond these elements pending encapsulation is not significant, but
can be, for example, a cyanoacrylate cement or Loctite Hysol Cool
Melt.RTM., or a DYMAX Corporation 200-CTH-series cement. The
encapsulated magnets are consistently mounted to the strips with
either the north or south poles directed downwards. As is seen in
FIG. 25, strips 35 end in recurved tines or prongs 36 with pointed
sharp ends sized and configured for fastening the patch-magnet to
the surface of the overlying fascial sheet by no deeper than to
undercut and catch hold of or clasp the superficial muscle fascia,
innervation avoided, causing the patient the least discomfort.
[2321] In use, an incision is cut into the integument only so large
as necessary to introduce the magnet, which is then positioned, and
pushed down, depressing the leaf spring supports. Upon releasing
the downward force on the magnet, the leaf-spring seeks to recover
to the curved form, engaging the end-prongs under the fascia. Some
force on the prongs and possibly pinching of the fascia when the
magnet is set in place are necessary to fully engage the prongs.
The prongs stimulate the generation of cicatricial (scar) or
fibrotic tissue that uninnervated, is numb, and sufficiently tough,
resists shear, preventing further incision and discomfort. However,
if following a suitable interval for healing, irritation due to the
prongs persists, then the subcutaneous or suprapleural magnets are
removed and the determination made whether to suture these in place
would remedy the problem.
[2322] If not, then esophageal tacking (magnetic esophageal
tracheopexy) to a magnet-wrap as described above is accomplished.
The bonded magnet 34 and strips 35 unit is then encapsulated by
dip-coating in a plastciser free nondegradable, hence biocompatible
plastic, such as polyvinyl chloride, which depending upon finer
chemical details, has a melting point that ranges from 175 to 212
degrees Fahrenheit, or higly polymerized (high molecular weight)
polypropylene with a melting point of 320 degrees Fahrenheit. These
are sub-demagnetizing melting points for the neodymium iron boron
magnets, which depending upon the exact lanthanoid material, have a
Curie temperature of around 590 degrees Fahrenheit.
[2323] The higher melting point of polypropylene has the additional
advantage of allowing the maker to sterilize the magnet-patch by
steam autoclave before placing it in the sterile package. The
previously presumed nonbiocompatibility of the plasticizers used to
make phthalate esters and polyvinyl chloride pliable has since been
discredited by the American Council on Science and Health 1999 and
the European Commission on Health and Consumer Protection
Directorate-General 2002. In manufacture, once cured, the incisive
ends of the prongs are exposed (denuded) by stripping away this
coating. To gold anodize more than the exposed prongs of the
unitized magnet with clip mounting prior to dip-coating is
considered redundant for use in this subcutaneous environment,
which in a patient free of subcutaneous disease, is substantially
noncorrosive, nondegradative, and pathogen free.
[2324] II2. Chemical Isolation of Patch-Magnet and Other Implanted
Components
[2325] Encapsulation to impart bioinertness to the miniballs,
stent-jackets, miniball-magnets (magnetized miniballs; magnetized
spherules) and subcutaneously or suprapleurally implanted
patch-magnets (clasp-magnets) described in connection with
extraluminal stenting is accomplished by overlayment with gold,
tantalum, titanium, or a bioinert plastic polymer resin applied by
dip-coating or lamination between sheets. Encapsulation to
chemically isolate toxic inclusions is addressed in relation to
clasp- or patch-magnets as usually incorporating a larger volume of
magnetized; such matter must always be isolated. This is no less
true when the material is incorporated as discontinuous to allow
breakdown in an implant otherwise absorbable. The radiopacity of
the miniballs notwithstanding, the tiny size of these encourages
improvement through the addition of an outer coating of
tantalum.
[2326] The further encapsulation of the tantalum layer with a
medium, such as starch or sugar-based, for delivering medication
upon dissolution does not detract from radiopacity. Of the various
methods for applying a coating of gold to these components,
conventional electrolytic barrel plating may produce a microporous
surface not entirely free of plating bath solution chemicals (see
Sahagian, R. 1999. "Critical Insight: Marking Devices with
Radiopaque Coatings," Medical Device and Diagnostic Industry
Magazine, Canon Communications, May 1999), in which case the
coating fails to provide the biocompatibility that was its object.
The materials and chemical isolation of the various components
described herein are further addressed under the section devoted to
each. Processes used to apply coatings to stents that are
applicable to the coating of miniballs include, for example,
ultrasonic spray technology such as the MediCoat and MicroMist
systems developed by Sono-Tek Corporation, Milton, N.Y.
[2327] III. Magnet-Wraps
[2328] A magnet-wrap or magnet-jacket such as that shown in FIGS.
22 thru 24 is configured as is a stent-jacket in as many types but
is generally larger with a shape-nonretentive or stretchable, such
as spandex, backing. If laminated, the magnetized layer when not
itself stretchable is segmented to allow expansion, putting it in
the discretely magnetized category, as addressed above in the
section entitled Types of Stent-jacket. A magnet-wrap can be used
as can a stent-jacket, to attract susceptible implants or passing
particles which it encircles or that lie outside and at a distance
from it; however, the use of a magnet-wrap to attract encircled
matter limits the pliancy of the backing, which is urged toward the
susceptible matter and limits the field strength that can be
used.
[2329] The magnetic poles along the wrap are usually uniform in
orientation. The magnet-wrap is intended primarily for application
of its radially outward tractive force on distant ferromagnetic
implants using the ductus it encircles as a mounting platform.
Concurrent use to treat the encircled ductus must coordinate the
force requirements for these different functions. In unusual
situations where the axially outward, or abaxial force of the
inwardly, or adaxially directed poles of a stent-jacket and the
axially inward, or adaxial, function of the outwardly or abaxially
directed poles of a magnet-wrap are both desired, the relative
prominence of either function and site suitability will determine
which type jacket is to be used. Exceptionally, a magnet-wrap used
as a cuff about an arm or leg, for example, is configured as a
magnet-wrap even though it functions as a stent-jacket.
[2330] External placement avoids the need for dissection to locally
encircle the ductus, usually an artery or vein. This is especially
the case when relatively large magnets are needed to draw drug
carrier particles from the blood into the ductus wall for a limited
time, after which the cuff is removed, Magnet-wrap function is
addressed above in the section entitled Concept of the Magnet-wrap.
A magnet-wrap looks like a small cuff and is secured about the
ductus used as a mounting platform by means of hook and loop
straps. It is used, for example, when intervening structures
preclude the use of suture to pull along the direction desired and
when subcutaneous or suprapleural patch-magnets or clasp-magnets,
addressed below in the section entitled Clasp-magnets, cannot be
positioned as desired.
[2331] III1. Use of a Magnet-Wrap
[2332] Considerations that pertain to the fitting of a magnet-wrap
to the substrate ductus are discussed in the previous section
entitled Jacket End-ties and Side-straps. The dimensions of
magnet-wraps vary with the size of the ductus to be encircled. For
most blood vessels, magnet-wraps are fifteen millimeters in wrap
around length and provided in two millimeter increments and
generally mount bar magnets that exert a tractive force
proportional to their dimensions. The width of the magnet-wrap is
determined by the length of the segment of the substrate ductus to
be encircled. The magnetic suspension of a collapsed dorsal
tracheal membrane is discussed in this section, as well as those
below entitled Subcutaneous and Suprapleural Clasp-magnets
(Patch-magnets, Treatment of Tracheal Collapse in the Cervical
Segments, i.e., Cephalad, or Anterior, to the Thoracic Inlet, and
Use of a Magnet-wrap about the Esophagus to Treat Tracheal Collapse
in a Small Dog.
[2333] The magnet-wrap is selected according to the circumference
and length of the substrate support ductus to exert the minimum
tractive force sufficient to attract the miniballs over the gap
present. The tightly rolled magnet-wrap is inserted through a local
incision or trocar portal. It is then unrolled and wrapped about
the substrate structure only so taut that the elastic webbed
surgical gauze 19, preferably made of polypropylene (Prolene.RTM.)
is not impeded from compliance to the smooth muscle movements of
the substrate vessel or duct and so that the magnets are directed
toward the target implants. Finally, the paper release strip is
stripped away from the hooks or loops, and end-flaps 24 are wrapped
around the underlying substrate structure securing the magnet-wrap
in place, the webbed texture of the gauze also assisting to reduce
the risk of migration.
[2334] When necessary, adding end-ties of hook and loop backed by
loosely braided multifilament spandex fabric specially woven for
breathability elastomer strapping, or as described in the section
on stent-jackets above, Durasil.RTM. suture (not shown), affords
added resistance to migration. It is considered obvious that the
attracted and attracting parts, herein magnets and ferromagnetic
pieces, such as in any wrap device described herein, could be
reversed in position to obtain a similar if not identical result.
In man, esophageal tracheopexy (tracheofixation) for tracheal
collapse, if not magnetic, is not without precedent (see, for
example, Masters, I. B. and Chang, A. B. 2005. "Interventions for
Primary (Intrinsic) Tracheomalacia in Children," Cochrane [Online]
Database of Systematic Reviews 19(4):CD005304; Cohen, D. 1981.
"Tracheopexy--Aorto-tracheal Suspension for Severe Tracheomalacia,"
Austrailian Paediatric Journal 17(2):117-21; Morabito, A.,
MacKinnon, E., Alizai, N., Asero, L., and Bianchi, A. 2000. "The
Anterior Mediastinal Approach for Management of Tracheomalacia,"
Journal of Pediatric Surgery 35(10):1456-1458).
[2335] Such can be accomplished by suspending the dorsal membrane
of the trachea once implanted with ferrous miniballs or stays from
the esophagus, whether the latter is provided with a magnet-wrap as
preferred or has magnetized miniballs or stays implanted. While
unconventional, a magnetic esophageal tracheopexy to treat collapse
or strictures of the airway seen in small dogs and small horses,
for example, as cited in the section above entitled Magnetic
Correction of Airway Collapse and described beginning with the
section below entitled Treatment of Tracheal Collapse in the
Cervical Segments, i.e., Cephalad, or Anterior, to the Thoracic
Inlet, has precedents in esophagopexy (esophagofixation),
tracheopexy, and the use of the esophagus to patch a tracheal
defect to treat many different conditions (see, for example, (Han,
Y., Liu, K., Li, X., Wang, X., Zhou, Y., and 6 others 2009. "Repair
of Massive Stent-induced Tracheoesophageal Fistula," Journal of
Thoracic and Cardiovascular Surgery 137(4):813-817; Freeman, D. E.
2005. "Surgery for Obstruction of the Equine Oesophagus and
Trachea," Equine Veterinary Education 17(3):135-141; Lillich, J.
D., Frees, K. E., Warrington, K., van Harreveld, P. D., Gaughan, E.
M., and Beard, W. L. 2001. "Esophagomyotomy and Esophagopexy to
Create a Diverticulum for Treatment of Chronic Esophageal Stricture
in 2 Horses," Veterinary Surgery 30(5):449-453).
[2336] The trauma associated with the implantation of sterile
miniballs in the esophagus to accomplish a magnetic tracheopexy
over the course of the esophagus dorsal to the trachea where no
injury or pathology had affected the esophagus is too discontinuous
to result in odynophagia, chest pain, or fibrotic or cicatricial
contracture and stricture as more expansive infection and serious
injury can produce in horses, for example (see, for example,
Waguespack, R. W., Bolt, D. M., and Hubert, J. D. 2007. "Esophageal
Strictures and Diverticula," Compendium: Equine Edition July/August
2007; Todhunter, R., Stick, J. A., Trotter, G. W., and Bowles, C.
1984. "Medical Management of Esophageal Stricture in Seven Horses,"
Journal of the American Veterinary Medical Association 185(7):
784-787).
[2337] Extraluminal stenting of Esophageal strictures following
injury, much as a sabre trachea, will usually prove too resistant
to alleviate by means of stenting (see, for example, Waguespack
2007 op cit: "Chronic strictures usually have progressed too far,
and the cicatrix is too firm to yield to dilation;" Lillich, J. D.,
Frees, K. E., Warrington, K., Van Harreveld, P. D., Gaughan, E. M.,
and Beard, W. L. 2001. "Esophagomyotomy and Esophagopexy to Create
a Diverticulum for Treatment of Chronic Esophageal Stricture in 2
Horses," Veterinary Surgery 30(5):449-453; Craig, D. and Todhunter,
R. 1987: "Surgical Repair of an Esophageal Stricture in a Horse,"
Veterinary Surgery 16(4):251-254; Nixon, A. J., Aanes, W. A.,
Nelson, A. W., and Messer, N. T. 1983. "Esophagomyotomy for Relief
of an Intrathoracic Esophageal Stricture in a Horse," Journal of
the American Veterinary Medical Association 183(7):794-796). Since
if extended, the tracheopexy may induce esophageal dysphagia, the
length is limited to only the obstructive portion of the dorsal
ligament, or membrane. The flaccid dorsal membrane of the trachea
should accommodate the passage of a bolus and prove an annoyance
only then. Placing the implants aside of the membrane minimizes
stretching. The field force is set to allow more pronounced
distention of the esophagus to momentarily separate the two.
[2338] III2. Magnet-Wrap Structure
[2339] As shown in FIG. 21, which shows the inner or substrate
ductus-directed face of a discrete magnet magnet-wrap and a
vertical section therethrough as seen edge on to its left side as
drawn, that is, with the outer surface facing toward the left hand
side, a magnet-wrap mounts magnets 18 that for minimum size, hence,
least obtrusiveness or encroachment upon neighboring structures,
are preferably made of high energy product sintered neodymium iron
boron which have been encapsulated for biocompatibility as
described below in the section on miniballs. A magnet-wrap to be
placed about a ductus with an external or adventitial tunic with
microvessels or nerves that must not be subjected to sustained
compression must be provided with a moisture barrier-coated
viscoelastic polyurethane foam lining, which is included in FIG.
21.
[2340] Four magnets 18 are shown only in an exemplary sense, the
size, number per unit area, and shape of the magnets of sintered
neodymium iron boron core for the maximum tractive force-to-magnet
mass and size ratios all varying according to the application.
Regardless of shape, magnets 18 are fixed in position by the same
running stitch 23 which is reversed to fill in gaps of the first
run for added strength, thus binding together the four plies of the
magnet-wrap, two behind and two in front of the magnets. The
backing or bandage portion of the magnet-wrap must be sufficiently
elastic to move with the outer surface of the substrate ductus
without loosening, bunching or migrating. Stitching 23 preferably
consists of nonabsorbable synthetic, strength retaining,
nonallergic thread or suture, single strand, or monofilament, to
discourage colonization, preferably made of polypropylene
(Prolene.RTM.) or nylon (Ethilon.RTM.) suture.
[2341] The two layers or plies to the rear (facing inside; toward
the outer surface of the substrate support ductus) consisting of
soft and elastic nonabsorbable, nonallergenic, and
colonization-resistant fiber-based gossamer grade woven surgical
gauze 19, preferably made of polypropylene. The inner of the two
outer layers consists of a loosely braided multifilament spandex
fabric layer 20 that is specially woven for breathability. The
outer layer consists of a breathable biocompatible fabric, such as
an open nylon webbing. The inner surface of the outer layer, which
serves to wrap around the ductus and secure the magnet-wrap on the
side opposite the magnets, is divided to omit the portion of the
underlying spandex layer 20 that overlies magnets 18.
[2342] The portions of the outer layer divided thus are stitched
against the outer surface of and toward the ends of spandex
(elastane, Lycra.RTM., Linel.RTM., Elaspan.RTM. and Dorlastan.RTM.)
layer 20. Small loops 21 on the outside (facing away from the outer
surface of the substrate support ductus) and hooks 22 mounted on
backing 24, usually made of nylon (polyamide, Zytel.RTM.) on the
inside (facing toward the outer surface of the substrate support
ductus) allow the end-ties or the two portions of the outer layer
to be wrapped entirely around and securely fastened behind the
substrate ductus. A silicone or wax coated paper release strip (not
shown) is applied by means of a thin layer of an adhesive with low
bond strength, such as corn starch, to either the hooks or loops to
prevent unintended fastening during placement.
[2343] IV. Clasp-Patches and Clasp-Wraps
[2344] IV1. Creation of a Magnetically Retractable Surface
Layer
[2345] Clasp-wraps (clasp wrap-surrounds, clasp-jackets,
clasp-bandages)are bandages or wrap-surrounds with ferromagnetic
clasps for engaging the outer tunic or tunics fastened to the inner
surface. A clasp-wrap is used to encircle a larger ductus that due
to disease, has collapsed or become stenostic and malacotic in its
outer layers. A clasp-patch does not wrap around the ductus but is
rather a local patch for fastening to the underlying tissue whether
fascial, adventitial, fibrosal, capsular, or pericardial, for
example. Clasp-wraps and the more localized clasp-patches are in
effect artificial adventitial or fibrosal tunics, or outer
capsules, lined when necessary with viscoelastic polyurethane foam
to protect small vessels and nerves and with ferromagnetic clasps
for fastening to the underlying tissue so that tissue can be
magnetically retracted.
[2346] While stays have many uses unrelated to stenting, a
clasp-wrap essentially duplicates the function of wide stays used
for stenting that are fastened to a mantle or wrap-surround for
encircling larger ductus to prevent pull-through of the
ductus-intramural implants under the magnetic tractive force used
to retract or distend and maintain the patency of the ductus.
Absent the means for inducing tissue infiltration and adhesion
described herein, miniballs have the least retentive potential,
that is, the greatest propensity toward pull-through. Placing a
miniball, then surrounding the ductus with a nonconstrictive
elastic wrap compresses the tissue overlying the miniball, and
reduces the tendency toward delamination.
[2347] Wetting the miniball with cement achieves adhesion only to
the tissue in direct contact with the miniball without adding
strength to the surrounding tissue. Additionally coating the inner
surface of the wrap with a tissue hardening agent will make the
overlying tissue less yielding or penetrable, reducing the tendency
toward pull-through. Finally, fastening the miniball to the inner
surface of the wrap by means of a small arm or clasp would impart
additional retentive strength in relation to the tractive force
imposed by a retracting magnet. However, the miniball is configured
for ballistic insertion, making it less resistant to pull-through,
and is introduced from within the lumen, making connection or
bracing thus unfeasible. Stays have extension circumferentially and
longitudinally to present significantly greater surface area for
retention and attraction than does a miniball, and stays are
introduced from outside the lumen.
[2348] However, inserted at an off-circumferential angle,
connection to an arm perpendicular to the plane of entry following
insertion followed by connection of the outer end of the arm to the
inner surface of a wrap-surround is not feasible. Alternative
approaches for imparting tunical integrity sufficient to allow
retractive stenting are addressed below in the section entitled
Clasp-wrap-Alternative Methods for Achieving Adhesion to the Outer
Surface of the Ductus. FIGS. 22 thru 24 show a clasp-wrap. The
clasps are oriented in a pattern that allows undercutting the outer
layers of the ductus while mildly urged by the spandex backing in
opposition The clasps are configured and can be coated to encourage
tissue ingrowth, and the inner surface of the wrap can be coated
with a cement that will provide temporary adhesion during tissue
infiltration.
[2349] In a hypothetical situation where miniballs should not be
coated with drugs to encourage tissue ingrowth or a cement and an
interval would best be allowed before placement of the stent-jacket
in a followup procedure, a clasp-wrap may allow stenting in one
procedure. This is not the case with stays, since both the stays
and stent-jacket are placed from outside the ductus through the
same incision or access portal, which does eliminate the need for
transluminal access and disruption to the inner tunics. Among
ductus-intramural implants, wide stays, especially when configured
with a deep outer texture that provides undercuts and ingrowth
channels, have greater retentivity or resistance to pull-through,
even without the stays and internal surface of the wrap wetted with
an adhesive.
[2350] The magnetically susceptible material need not be confined
to the clasps but can consist of threads incorporated into the
stretchable backing, for example. As shown in FIG. 22, which shows
the inner or substrate ductus directed surface-of a clasp-wrap,
FIG. 23, which shows one of the ferromagnetic metal or ferrous
metal particulate impregnated plastic clasps in detail, and FIG.
24, which shows a clasp in section, mechanical fastening is
accomplished through the use of clasps 26, each with a single very
sharp prong tip directed downward at an angle for undercutting the
more superficial layers of the substrate ductus. In overall
conformation, the prong is similar to but usually much smaller than
those used in athletic bandages. A moisture barrier-coated
viscoelastic polyurethane foam lining for placement about a ductus
of which the vascular and nervous supply must not be subjected to
sustained compression is shown at the bottom of FIG. 24.
[2351] Prongs 26 are preferably made of a magnetically susceptible
stainless steel or elgiloy cobalt-chromium-nickel steel and
perforated or deep-textured for tissue infiltration and wetted with
phosphorylcholine, for example, to suppress an adverse tissue
response. The application of a tissue cement is considered
unnecessary. While the opposition of the prongs toward either end
of the clasp-wrap makes dislodgement improbable, the prongs can
also be coated with a solder that encourages tissue infiltration,
the solder denatured by warming the clasp-wrap once placed, the
efficacy of using a laser to denature the solder contingent upon
the number and position of the prongs.
[2352] Due to cell turnover, coating the internal surface of such a
wrap with an adhesive is a only a temporary measure for achieving
adhesion to the adventitia or fibrosa until the clasps become
ingrown by the surrounding tissue. The clasp-wrap can be retracted
by a stent-jacket or clasp- or patch-magnets positioned about the
periphery. The latter usually use larger neodymium magnets and can
be positioned at a greater distance. This can be of value when
clearance is a problem and/or a clear field is wished preserved for
a prospective surgical procedure. The need for a clasp-wrap is
usually due to weakness in the outer layers of the substrate ductus
as disallows the retention of ductus-intramural implants. Any
adhesive used to coat the inner surface of a clasp-wrap must be
stretchable when cured.
[2353] The clasps used to engage the outer surface of the substrate
ductus may be magnetically susceptible, or the intervening
material, usually spandex, may be woven of magnetically susceptible
coated fibers. When the collapse or stenosis is radially
asymmetrical, the clasp-wrap can be made susceptible for use with
clasp-magnets, magnet-wrap, or a stent-jacket of like asymmetry or
asymmetrical positioning. A claspless wrap-surround incorporating
magnetically susceptible and radially asymmetrically might be used
to. A clasp-wrap must not arouse an adverse tissue reaction or
disrupt autonomic function. Unless woven to be absorbable, of
glycolic acid-based fibers, for example, with absorbable clasps of
such matter in solid form, the wrap must not disintegrate.
[2354] While the clasps themselves are shown as the magnetically
susceptible component, a clasp-wrap that incorporated magnetically
susceptible matter by coating or lamination with encapsulation for
chemical isolation of the toxic material following breakdown is an
obvious alternative, as is making clasps and the material of the
wrap itself susceptible. Such requires that it be sufficiently
elastic to move with the surface during intrinsic and gross
movement, and remain permeable to gas and moisture. A clasp-wrap to
be placed about a ductus with a fibrosal (external, adventitial)
tunic supplied by a microvasculature or nerves susceptible to
injury from compression under a wrap-surround must be provided with
a moisture barrier-coated viscoelastic polyurethane foam
lining.
[2355] The use of clasp-wraps and magnet-wraps is subject to the
results of the adventitia-media or intra- or inter-laminar
separation (delamination) test described below under the section
entitled In Situ Test on Extraluminal Approach for Intra- or
Inter-laminar Separation (Delamination). As is true of
stent-jackets and stays, a clasp-wrap has as one basic object
compliance with the intrinsic movement in the wall of the vessel or
duct. Clasp-wraps are used with more strongly magnetized
components, namely magnet-wraps, patch-magnets, and more strongly
magnetized impasse-jackets, and seldom if ever with stent-jackets
and magnetized miniballs, stays, and arrays thereof, which are too
weakly magnetized to attract clasp-wraps.
[2356] Clasp-wraps for temporary use, to include the clasps, are
made entirely of absorbable materials such as those specified in
the section entitled Absorbable Stent-jacket Expansion Insert
Materials with Relatively Short Breakdown Times, among others. A
clasp-wrap can be used with a stent-jacket to exert tractive force
either eccentrically or entirely around the ductus with equal or
different tractive forces over different arcs. Retracted by means
of a distant rather than encircling source of magnetic attraction,
such as a magnet-jacket (magnet-wrap) or a subcutaneous or
suprapleural clasp magnet or by a plurality or some combination of
these, the attractive field is angularly limited and therefore
eccentric. When the ductus is malacotic (softened, weakened),
miniballs and stays with too little contact area to adequately
distribute or divide the force of attraction are likely to pull
through.
[2357] When the malacia or intra- or inter-laminar separation
(delamination) is superficial (peripheral, adventitial), the use of
a conventional (endoluminal) stent (because it is medial or deep to
the diseased outer layers) is indicated. When the diseased tissue
is more medial (deeper in relation to the outside surface), an
endoluminal stent should be avoided. A diseased ductus that is not
implantable without perforation, pull-through, or intralaminar
separation or delamination using less densely spaced apart implants
can sometimes be grasped about through use of a clasp-wrap, which
more evenly distributes the tractive force and thus is better able
to resist detachment. Such use is especially appropriate where the
ductus wall will remain in need of support after healing with the
weakened condition having subsided, where the use of a wrap-around
graft of stronger tissue would demand much time to heal, and an
anastomotic graft would pose a risk of leakage as well as take time
to heal.
[2358] More specifically, to avoid a lengthy preliminary interval
for healing before a second procedure to implant miniballs or stays
can be performed that the urgency of the condition may not allow,
such a synthetic exogenous patch material is preferable to even an
autogenous graft. Furthermore, any donor tissue would have to
exhibit the properties of strength and elasticity substantially
unique to the type tissue of the ductus. Made entirely of
nonallergenic synthetics, a stent-jacket likewise requires no
antecedent procedure and poses no risk of rejection. Without a
second operator to harvest the donor tissue, the use of synthetic
materials saves even more operating time as well as avoids
specifically harvesting trauma. Approaches that would so strengthen
the outer layers of a diseased ductus that miniball or stay
implants could be used without the need for a clasp-jacket require
further development.
[2359] These include a bioinert penetrating and hardening resin for
wetting the outer surface of the ductus that would have sufficient
pliancy upon curing as not to interfere with autonomic motility,
and the use of radio frequency treated collagen (see, for example,
Shields, C. A., Schechter, D. A., Tetzlaff, P., Baily, A. L.,
Dycus, S., and Cosgriff, N. 2004. "Method for Creating Ideal Tissue
Fusion in Soft-tissue Structures Using Radio Frequency (RF)
Energy," Surgical Technology International 13:49-55; Mohr, L. G.
Jr. and Edwards, S. D. 1999. "Treating Aneurysms by Applying
Hardening/Softening Agents to Hardenable/Softenable Substances,"
U.S. Pat. No. 5,921,954 (expired Jul. 16, 2003 for nonpayment of
maintenance fees). The many tissue fixatives developed for
microscopy do not exhibit both the pliancy and tissue compatibility
essential for the present purpose.
[2360] Provided the ductus is not too malacotic, a clasp-wrap with
a sufficient number of ferromagnetic clasps per unit area to
undercut the outer layers of the ductus, especially when bonded to
the surface of the ductus with a stretchable tissue adhesive and
devised to allow tissue infiltration to compensate for the
inevitable breakdown in the adhesive over time, can adhere longer
than is allowed through the use of an adhesive alone. In the
adverse chemical milieu inside the body, an adhesive breaks down
quickly when the surface of the tissue to which it is bonded is
replaced through normal cell turnover. Considerations pertinent to
the securing of a clasp-wrap to the substrate ductus are addressed
above in the section entitled Jacket End-ties and Side-straps.
[2361] The clasps alone are used to retain the clasp-wrap against
the outer surface of the ductus; alternatively, the clasp-wrap, to
include the prongs, can be coated entirely with an adhesive,
preferably one that exhibits elasticity upon curing, or partially
with an adhesive and partially with phosphorylcholine to reduce
tissue reaction, or provided with hook and loop extension at either
side to assist in retention. Clasp-wraps generally do not require
supplementary stabilization by means of side-tethers as might
stent-jackets. Synthetic and cleaned of any polymerization or
environmental contaminants, spandex elastomer, which is a block
copolymer of polyurethane segments alternating with segments of
polyethylene glycol, is non-sensitizing and nonallergenic. A
spandex backing to comply with expansion and contraction in the
substrate ductus is applied for the quiescent diameter and can be
used to expedite far side clasping on placement. As seen in FIG.
22, the clasp groups are oriented in opposition.
[2362] This not only produces a secure attachment once placed but
facilitates placement by allowing the operator to pull at the ends
with the spandex backing stretched while moving the wrap behind the
ductus from side to side so that all clasps will remain engaged
when the wrap is released. Care must be given to not strentching
the backing to the degree that the ductus will be compressed while
quiescent. Alternatively, the operator can pull at one end so the
restorative force assists to engage the clasps with points facing
in the same direction. Where the substrate structure is a cord or
sheath of constant diameter, the restorative force of the spandex
backing is used only to expedite clasping during placement and not
for compression. As shown in FIGS. 21 thru 23, the clasp-jacket is
made of layers of spandex or elastane 24. Spandex is sold under the
trade names of Lycra.RTM., Linel.RTM., Elaspan.RTM. and
Dorlastan.RTM..
[2363] Such material is less susceptible to microfracture and
brittleness over time than is natural rubber, and is thus able to
resist the chemical insults associated with circumvascular
placement for a long time. Spandex effectively does not
disintegrate in circumvascular placement. It is considered obvious
that the attracted and attracting parts, herein magnets and
ferromagnetic pieces, such as in any wrap device described herein,
could be reversed in position to obtain a similar if not the same
result. As shown in FIG. 21, formations of individual clasps are
mounted on woven stretchable backing 27 of spandex, which allows
air to reach the surface of the substrate ductus. Backing 27 can
also be made of plies of spandex alternating with plies of surgical
gauze.
[2364] Alternatively, the inner surface of the minball-jacket can
be coated with a highly tacky pressure-sensitive
hypoimmunologically processed adhesive consisting of a mixture of
synthetic rubber, which has high initial bond strength that tends
to degrade over time, and pressure sensitive acrylic emulsion
polymer adhesive, which tends to increase in bond strength over
time. Improved breathability is obtained by introducing small
perforations in the backing. For such an adhesive to bond well may
require that the outer surface of the ductus be dried with a blow
dryer or by swabbing with an absorbent cloth. Clasps 30 with
mutually facing prongs can be arranged in different formations, to
include placing all facing in one direction as a group on one side
of the internal surface with those facing in the opposite direction
on the opposite side of the internal surface, or in rows wherein
the prongs of adjacent clasps face one another in pairs.
[2365] As shown in FIGS. 22 and 23, an individual ferromagnetic
clasp consists of a single prong 26 bent when die-cut to be
continuous with a small stoop-like tab containing a hole. The
dimensions of the stoop-tab 29 are determined by the properties of
the spandex (elastane) or other stretchable and breathable clasp
backing material 27 used, being made large the softer, more pliant
so that the clasp is overly inclined under the tractive force of
the magnets, and more subject to being torn is the intervening
material. Rivet 28 is passed through this hole, through the
intervening spandex sheeting and a flange cover-plate on the outer
surface. Tab-stoop of prong 26, flange cover-plate 25, and rivet 28
thus cooperate to clamp spandex layer 27 and fix prong 26 in
position.
[2366] The prongs, which depending upon the condition of the ductus
are chosen in length to penetrate the adventitia or media (but not
perforate into the lumen), are textured and fenestrated or punched
to encourage tissue infiltration and are encapsulated for
bioinertness as specified in the sections on miniballs and stays.
Flange cover-plate 25, to include fenestrae and bends, and prongs
26 are die-cut, the angle of the bends varying with the overall
dimensions according to the type substrate ductus and depth of
penetration desired. Whereas a magnet-wrap need not firmly adhere
to the outer surface of the neighboring ductus it mantles about, a
clasp-wrap must adhere to the outer surface of its substrate ductus
immediately upon placement despite magnetic traction on the clasps.
To prevent irritation to the substrate ductus, all surfaces of the
clasps facing inward, and to prevent irritation to neighboring
tissue, all surfaces of the clasps facing outward, must be flat and
smooth.
[2367] IV2. Use of a Clasp-Wrap
[2368] The clasp-wrap is inserted through a small incision in the
body wall while still tightly rolled, and an adhesive if any
lightly coated onto the fascia cleaned surface of the ductus. The
clasp-wrap is then positioned perpendicularly to the ductus,
stetched only enough to allow the prongs to fully engage the outer
layers of the ductus without perforating into the lumen or
restraining the intrinsic motility, then pushed down gently with a
fingertip to assure good contact and adhesion. Provided the ductus
is motile upon application, the use following the clearing away of
diffuse fascia of a long-chain methacrylate cement in a light film
to bond the clasp-jacket to the outer surface of the ductus need
little impede stretching of backing 27 nor smooth muscle motility;
the stretching of backing 27 notwithstanding, adhesion generally
succeeds at a sufficient number of points to maintain the bond
until such time as tissue integration of the prongs takes over
adhesion when this is eventually lost due to tissue replacement. In
some instances, the methacrylate is applied with a multi-dot
applicator for improved spandex stretch compliance.
[2369] IV3. Clasp-Wrap-Alternative Methods for Achieving Adhesion
to the Outer Surface of the Ductus
[2370] IV3a. Stays Configured and/or Coated to Promote Tissue
Infiltration and Adhesion
[2371] Stays are addressed below in the section entitled Arcuate
Stays. A malacotic ductus may be unsuited to treatment by ballistic
means, and a severly malacotic or otherwise weakened ductus will be
untreatable by any of the means and methods described herein with
the possible exception of widely configured versions of
nonferromagnetic stays with a broken surface to encourage tissue
infiltration, adhesion, and cement as described below, all of the
other means necessitating some resistance to tractive force applied
from without. If endoluminal stenting must also be discounted, then
a bypass graft is indicated. When malacia would not allow ballistic
implantation but is not so severe or expected to progress to the
degree that the wall of the ductus must not be grasped and retained
under tension sufficient to maintain patency, then various
nonballistic, or stay, methods and means, as addressed below in the
section entitled Arcuate Stays, may apply.
[2372] IV3b. Injectable Magnetic Fluids
[2373] Existing injectable magnetic fluids (not ferrofluids) are
meant for temporary use to assist in manipulation during delicate
ophthalmic procedures (Dailey, J. P. Phillips, J. P., Li, C.; and
Riffle, J. S. 1999. "Synthesis of Silicone Magnetic Fluid for Use
in Eye Surgery," Journal of Magnetism and Magnetic Materials
194(1):140-148(9); and U.S. Pat. Nos. 6,464,968, 654,636, and
6,612,311). Quickly dissipated, such means are inapplicable for the
present purposes. At the time of filing, a bioinert and therefore
permanent injectable magnetic fluid was not available.
[2374] V. Miniballs
[2375] V1. Miniature Ball Implants
[2376] Miniballs (miniballs, spherules, minispheres) for use in
simple pipe-type barrel-assemblies generally range in diameter from
0.7 to 2.4 millimeters, while those for use in radial discharge
barrel assemblies for use other than in the airway range between
0.14 and 2.4 millimeters. With ferromagnetic miniballs, sphericity
presents a poor gap for magnetic flux. This is compensated for
through the use of neodymium iron boron lanthanoid magnets to
attract these. Neodymium magnets afford the highest energy product
and thus the smallest size and mass for the field strength exerted.
The availability of minute magnets minimizes if not completely
eliminates encroachment upon and abrasion against neighboring
structures. Discomfort to the patient and the sequelae that can
result from chronic irritation are thus eschewed.
[2377] At the same time, ballistic implantation, as described
herein, is as clean, i.e., as bloodless and atraumatic as possible,
while readily lending itself to aseptic delivery. Miniballs to
serve as the intraductal component of a permanent extraluminal
magnetic stent usually have a solid core of ferromagnetic metal
that is encapsulated for chemical isolation. Otherwise, the
miniball can contain ferromagnetic pieces dispersed in an
absorbable matrix such as sugar where the matrix can include
therapeutic substances, such as drugs, and the pieces are shaped to
present proportionally more lateral surface area for magnetic
attraction but include projecitons shaped to stop extraction
through the adventitia under the magnetic force. Those for
temporary magnetic stents have superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder dispersed in an
absorbable matrix, such as polyglycolic acid.
[2378] Miniballs to be infixed at locations from which dislodgement
is a possibility, especially along the arterial tree, are secured
not only by being wedged in position but by tissue infiltration or
by deliberately coating the miniball with an irritant to prompt the
body to isolate or entrap the implant much as a cyst, with or
without an adhesive outer coating that temporarily fixes the
implant in position and contains the substance or substances to
encourage such a reaction. Moreover, multiple means will be
described for preventing a miniball that despite these measures
enters the circulation from forming an embolism. A prepositioned
impasse-jacket will arrest and retain a loose miniball mid- or
postprocedurally and allow the miniball to be extracted to a safe
location or outside the body.
[2379] Upon dissolution of the absorbable miniball, the iron is
assimilated by the body. Magnetized miniballs can be used to
attract drug and/or radionuclide carrier nanoparticles or
microspheres, for example. The stenting, or ferrous, component of
the miniballs, usually a unitary spherical core, is encapsulated to
be biochemically inert, and may be outer-layered or coated with
anti-inflammatory, antibiotic, blood coagulation-related,
antiangionic, chemotherapeutic, or other medication, with or
without a radionuclide or irradiated seed component. Drugs for
delivery as miniballs to achieve focused concentration likewise
have superparamagnetic magnetite or maghemite nanoparticles or
finely grained powder dispersed to allow any mispositioned
miniballs to be retrieved.
[2380] Absorbable miniballs can also be made to liberate medication
during dissolution, and numerous combinations of medication and
other type stays are possible. Recovery electromagnets are always
situated in the muzzle-head proximate to the points of miniball
insertion. Whether for sustained attraction, arrest and/or
recoverability if entering the circulation, or for induction
heating, virtually all miniballs contain ferrous content.
Generally, absorbable miniballs consisting of medicinal or other
therapeutic substances contain dispersed superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder which
is gradually released as the miniballs dissolve, while permanent,
or stenting, miniballs contain a core or larger distributed
particles of rectangular prismoidal conformation for greater
magnetic susceptibility.
[2381] Magnetic susceptibility is satisfied with the inclusion of
sufficient superparamagnetic magnetite or maghemite nanoparticles
or finely grained powder, which presenting a maximized surface
area, is absorbed quickly. Incorporating larger grains of iron
whether by sintering the powder allows heating a miniball by
magnetic or electromagnetic induction. Heat has numerous
applications, to include palliative warming of the surrounding
tissue, accelerating its healing time, releasing and accelerating
the uptake of a drug or other bioactive substance, and effecting
and accelerating the disintegration of an absorbable miniball
itself. If absorbable, the larger grains whether sintered still
present much surface area for relatively quick uptake.
[2382] Miniballs for placement along the vascular tree as the
intraductal component of an extraluminal magnetic stent have small
projections at different angles with an undercut-textured surface
which are embedded within a spherical outer casing or jacket such
as one containing a sugar which is absorbed following placement.
Once anchored by tissue infiltration, a direct blow that crushed or
severed the vessel ending the flow of blood therethrough would not
dislodge the tissue fused miniball. The site must then be entered
for repair, whereupon the miniball is easily extracted with an
electromagnet. In FIG. 27, core 37 can be an element in the
intravascular component of an extraluminal magnetic stent or
medicinal. With a core of either purpose, concentric overlaying
layers 38,- 39, and 40 can consist of or incorporate drugs and/or
other therapeutic substances, such as a surgical cement.
[2383] The section above entitled Field of the Invention and that
below entitled Cooperative Use of Impasse-jackets in Pairs and
Gradient Arrays, among others comprehend a core 37 which
incorporates a resonant circuit responsive to a magnetic field
alternating at radio frequency (see Niwa, T., Takemura, Y., Inoue,
T., Aida, N., Kurihara, H., and Hisa, T. 2008. "Implant
Hyperthermia Resonant Circuit Produces Heat in Response to MRI Unit
Radiofrequency Pulses," British Journal of Radiology 81(961):69-72,
available at
http://bjr.birjournals.org/cgi/content/full/81/961/69). When the
concentric layers are arranged in least to greatest melting and/or
traction dissolution points from the periphery to the center, the
layers can be released in this order, an alternating magnetic field
used to effect heating and the constant tractive force exerted by
the stent- or impasse-jacket, for example, extracorporeally or by
remote control thereafter used to draw the drug and/or radioactive
nanoparticles to and into the diseased tissue.
[2384] The succesive layers or shells of the miniballs can be
constituted to affect a layer previously released as adjuvant or
neutralizing, and successive layers of multiple miniballs, such as
held within an impasse-jacket can act on one another thus. Ductus
entry and exit pairs can control the medicinal and other
therapeutic substance exposure of a delimited segment of a ductus.
When each concentric layer incorporates magnetically susceptible
drug and/or radionuclide carrier nanoparticles, each layer can be
shed in temperature and tractive force order of dissolution by
remote control. Specifically, an alternating magnetic field will
not only excite a resonant circuit within the core but the
nanoparticles in each layer.
[2385] Once released within the bloodstream, for example, the
constant magnetic tractive force exerted by a stent-jacket,
impasse-jacket, or patch-magnet, for example, will draw the
nanoparticles against and into the jacketed lesion in the lumen
wall. Further to the risk of a release of implants into the
bloodstream in the young, stenting temporarily stenosed vessels
with an extraluminal stent made of chemically isolated absorbable
and absorbable matrix-bound components using absorbable stays
demands extraductal entry but avoids the threat of migration due to
normal growth (see, for example, Epstein, M. L. 2004. "Does a
"Split" Stent Make Sense?," Catheterization and Cardiovascular
Interventions 62(4):511). The choice of miniballs as implants must
consider the profile and strength of the lumen wall following or
without an angioplasty.
[2386] Methods for testing the lumen wall in situ are addressed
below in the section entitled In situ Test on Endoluminal Approach
for Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation. Later degenerative conditions capable of advesely
affecting or defeating an extraluminal stent would likely prove
equally detrimental with an endoluminal stent. Such conditions
include softening of the arteries (arteriomalacia, angiomalacia)
associated with heart disease (see, for example, Bouhoutsos, J. and
Morris, T. 1973. "Femoral Artery Complications after Diagnostic
Procedures," British Medical Journal 3(5876):396-399.). The
stent-jacket resists aneurysmal distention resulting from untreated
hypertension. To defeat the stent, the condition would have to so
weaken the tissue of the lumen wall that miniballs could be
released out of the vessel through the adventitia, or despite the
retractive force of the stent-jacket, into the circulation.
[2387] Patients with a degenerative condition that could reduce the
retentive strength of the wall tissue may still warrant the use of
wider stays before proceeding with a graft. The barrel-assembly
includes means such as recovery electromagnets and an embolic
filter to prevent the midprocedural loss of a miniball. Additional
means for intercepting and resituating to a safe location or
recovering a miniball are addressed below in the section entitled
Steering and Emergency Recovery of Implants with the Aid of an
External (Extracorporeal) Electromagnet. Producing a trajectory or
path of insertion little wider than the miniball itself,
implantation by such means is least disruptive to surrounding
tissue. Cells along the trajectory and its terminus are crushed and
release fluid contents; however, this injury is small in extent,
highly localized, and the resulting inflammation is medically
manageable.
[2388] Furthermore, the fluid released lubricates the spontaneous
rolling around into optimal polar orientation of magnetized
miniballs having a core of neodymium lanthanoid and expedites the
delivery of medication from miniballs with an outer coating that
contains a drug or drugs. However, implantation by such means
requires projectiles that are spherical. As shown in the cross
sections of FIGS. 26, a miniball consists of an iron or steel core
37. When tissue compatible, core 37 represents the sum total of the
miniball; if not, the miniball is plated with gold, heated, and
sputtered to remove contaminants (see Edelman, E. R., Seifert, P.,
Groothuis, A., Morss, A., Bornstein, D., and Rogers, C. 2001.
"Gold-coated NIR Stents in Porcine Coronary Arteries," Circulation.
103(3):429-434).
[2389] Alternatively, stainless steel tending to afford relatively
low radiopacity, the miniball is coated with tantalum, such as with
Danfoss Tantalum Technologies Danfoss Coating.RTM., in which case
38 represents the outermost coating, the additional layers in the
figure not required. When patient life expectancy justifies the
additional expense, the implants are encapsulated in gold,
platimum, or tantalum, which are radiopaque. Other than for those
having a neodymium lanthanoid core, the encapsulation of implants
for bioinertness is precautionary. When the patient is expected to
survive for years and the chemical breakdown of core 37 could
release a nocuous constituent over time, then the core 37 is
encapsulated for bioinertness by overlayment with gold, tantalum,
titanium, all of which additionally contribute high radiopacity, or
a bioinert plastic polymer resin shown as layer 38 surrounding the
core.
[2390] Should core 37 be enhanced in radiopacity with a coating of
tantalum before encapsulation in a resin for even greater
isolation, the tantalum coating is represented by 38 and the resin
by 39. If not itself of tantalum, which is bioinert and affords
good radiopacity, layer 38 for chemically isolating the core can be
coated with an additional layer 39 of tantalum. Still refering to
FIG. 26, a steel-core 37 gold plated (layer 38), and microfused
(layer 39) miniball may be further coated with a layer of tantalum
40. For magnetic optimization, core 37 is preferably made of a
corrosion-resistant ferromagnetic stainless steel, and
proportionally large as possible within the thickness constraints
of the outer coating materials when present. Ferromagnetic
stainless steels include those of 400 series and heavily cold
worked 8 percent lanthanoid 316 in CF8M alloy.
[2391] Ferritic, martensitic, and to an extent, less austenitic
stainless steels can also be used as cores. Since gold plate can
present microfractures, unless an outer coating of tantalum already
applied for improved radiopacity also fully seals the exterior, a
process whereby additional gold is applied to completely seal the
core, Microfusion.RTM., is applied, or otherwise, replating, in
which case layer 39 represents this layer. In addition to close
inspection under a stereomicroscope, microfractures of the
electroplated surface can be detected by standardized corrosion
protection tests, such as the salt spray or salt fog test (American
Society for Testing and Materials Standard B 117) and Kesternich
(Deutsches Institut fur Normung Standard 50018 or International
Organization for Standardization Standard 3231) tests.
[2392] Thus, if gold-electroplated, surface contaminants must be
eliminated and any voids filled by Microfusion.RTM. or vacuum
deposition plating, which involve temperatures, typically 70-120
degrees Fahrenheit, well below the 590 degree Fahrenheit Curie or
de-magnetizing temperature of neodymium iron boron lanthanoid
magnets. An outer coating that consists of a polymer rather noble
metal is applied by means of in-situ or matrix polymerization,
which methods are widely used in the manufacturing of
pharmaceuticals. Gold is of high specific gravity or density
relative to water, but in the tiny amounts used, not such as would
result in too heavy an intraductal component of an extraluminal
stent.
[2393] For miniballs and miniball-magnets, however, adjustment in
plating thickness allows precision in achieving a certain mass.
Combined with variability in the material used to encapsulate these
components, some variability in core and wide variability in
plating thickness may be applied to achieve considerable exactitude
in mass and aeroballistic performance. When the combination of
concentric layers as depicted in FIG. 26 or 27 results in a
diameter that is too large for the barrel-tubes, consideration
should be given to use rotary magazine clips that have been loaded
to provide irradiated and/or medication and ferromagnetic miniballs
sequentially or in alternation, or miniballs that variously combine
layers to provide adequate coverage over the area to be
treated.
[2394] In the improbable circumstance that such becomes necessary,
for arterial and venous application, miniballs must have an outer
coating of sufficient tensile and shear strength to withstand
stereotactic resituation into safe tissue or if superficial,
extraction, as addressed below in the section entitled Steering and
Emergency Recovery of Implants with the Aid of an External
Electromagnet.
[2395] V2. Miniball Types, Radiation-Emitting, Medication,
Drug-Eluting Magnetized, and Magnetized
[2396] Temporary miniature balls and stays can consist entirely of
absorbable medication, sealants, or mixtures of these and can be
provided with concentric shells of different medications and/or
sealants wherein each layer has a prescribed rate of release.
Nonabsorbable miniature balls and stays used to deliver radiation
at dose-rates higher than could safely be left in place can be
coated with absorbable layers of medication or sealants so that
only the superparamagnetic magnetite or maghemite nanoparticles or
finely grained powder-coated radiation seed would subsequently be
recovered, as addressed above under the section entitled Background
of the Invention, 4. Necrosis- and atherogenesis-noninducing
conformation.
[2397] For emergency interception and extraction midprocedurally
using a preplaced impasse-jacket or an external electromagnet,
sufficient ferromagnetic material must be dispersed throughout an
absorbed, to include a drug-releasing miniball, so that its
magnetic susceptibility does not degrade with its dissolution to
the point where it is no longer extractable. For arrest and
extraction, the ferrous material is ordinarily superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder; for
heat induction, iron grains. Uniform distribution also affords
greater iron particulate surface area for absorption and eliminates
any need to extract a relatively large core.
[2398] Permanently implanted miniballs and stays that are
ferromagnetic for use with a stent-jacket or which emit radiation
can be overlain with multiple absorbable outer layers of medication
and/or sealants, to include the release of genetic material (see,
for example, Walter, D. H., Cejna, M., Diaz-Sandoval, L., Willis,
S., and fifteen other authors 2004. "Local Gene Transfer of
phVEGF-2 plasmid by Gene-eluting Stents: An Alternative Strategy
for Inhibition of Restenosis," Circulation 110(1):36-45). The
preparation of radioactive miniballs, whether for aeroballistic
discharge or for bonding between the lining and base-tube of a
stent-jacket, for example, can be accomplished by conventional
means as used to prepare radioactive seeds or means such as those
described by Good in Good, R. R. 1994. "Endocurietherapy," U.S.
Pat. No. 5,342,283, with continuation-in-part Good, R. R. 2000.
"Endocurietherapy," U.S. Pat. No. 6,099,457.
[2399] If necessary, the internal surface of the base-tube is
scored or etched, and a suitable adhesive, such as Master Bond
EP42HT-2ND2 used to bond the radiation microspheres in the number
and type required between the base-tube and the foam lining.
Hypothetically, absorbable stays consisting of medication in layers
could be used as structural buttresses to support a stenosed or
collapsed (malacotic) ductus during and for the purpose of
promoting recovery. Any miniball or stay, temporary or permanent,
can be coated with absorbable layers of medication, sealants, or
combinations of these whether in a given layer. That these various
factors as to miniball or stay, permanent or temporary, with or
without outer layers of medication, sealants, or both, and so on,
might be permutated into numberless specific combinations is
considered obvious, as is the fact that different types of
intramural implants could be used in a single ductus.
[2400] V3. Medication (Nonstent) Implants and Medication-Coated
Miniballs, Implants, and Prongs
[2401] Medication miniballs and stays are not used for magnetic
stenting but to concentrate drugs at the treatment site. These
consist predominantly if not entirely of medication. The contents
may be absorbed entirely, or if an open or closed loop `smart pill`
and/or a radiation emitting seed which has been coated with
medication, for example, may not be fully absorbed. Medication
miniballs and stays contain sufficient, usually dispersed,
ferromagnetic material (almost always superparamagnetic magnetite
or maghemite nanoparticles or finely grained powder) to allow
recovery if midprocedurally mispositioned, dropped, or lost. By
contrast, medicated miniballs and stays are coated, doped with, or
contain medication in the form of embedded particulates or
microspheres, for example, primarily intended for use in
extraluminal magnetic long-term if not permanent stenting.
[2402] These consist of a ferromagnetic core often coated with
medication and/or other therapeutic substances. Miniballs for
temporary magnetic stenting also have superparamagnetic magnetite
or maghemite nanoparticles or finely grained powder dispersed
throughout an absorbable matrix, which may or may release
medication as it becomes absorbed. As addressed above in the
section entitled Significance of Antixenic Sterile Tissue Reaction,
to delay if not prevent a foreign body reaction, implants and
prongs that penetrate tissue to secure implant backings in place
are coated with reaction-suppressive substances, such as
phosphorylcholine, dexamethasone, and/or curcumin. Except when no
ferrous material is included in a medication miniball, the
distinction between medication and medicated miniballs depends
then, upon the relative proportion of nonferrous to ferrous
ingredients.
[2403] Whereas the magnetically susceptible core of a medicated
miniball for magnetic stenting is proportionally larger and
enclosed within thinner coatings of medication, that of a
medication miniball requires no more mass of susceptible material
than is necessary to allow its retrievability were the miniball
improperly placed. Whether in the form of a core or dispersed, the
susceptible material included in a medication miniball, generally
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder, is usually prepared for complete dissolution so
that the medication miniball is completely absorbed. Rotary
magazine clips can be loaded to deliver ferromagnetic, medication,
or medicated miniballs in any sequence.
[2404] Medication miniballs can consist of ingredients that have
been interspersed, or mixed, or that consist of concentric layers
of medication surrounding a core of another medication or a
proportionally small core of ferrous metal. The ferrous core can be
powdered for dissolution or encapsulated for magnetic stenting and
tissue compatibility once denuded by absorption of the surrounding
medication. The core can be an irradiating seed, one or a
combination of drugs in the form of powder fused with or without an
absorbable outer shell which shell can itself incorporate
medication and/or determine dissolution time, and so on.
Shot-groups about the rotary magazine clip can include the same or
different kinds of miniballs.
[2405] The shot-groups can, for example, include miniballs having a
ferromagnetic core that is or is not surrounded by medication,
layers of different medication, within or not within an absorbable
shell of which the dissolution time can be adjusted by altering the
thickness or the material of which the shell is made as addressed
above in the section entitled Stent-jacket Expansion insert
Materials Having Relatively Short Breakdown Times. Controlled
dissolution of the medication within a miniball following infixion
is preferred to the release of smaller contained miniballs upon
impact, which is less predictable and controllable. The delivery of
medication squarely into the target tissue in the form of a
spherical pill having a dissolution or release time set by means
long established in the field of tablet manufacture allows a degree
of localization, time release control, and--using the enclosed or
torpedo-shaped muzzle-heads described herein--access to lumina of
small diameter, which endoscopic injection cannot approach.
[2406] Provided the force of impact is tested as described below in
the section entitled Pressure Registration Pretest, where the
density of implantation is not high and the accuracy of implant
location is not critical, medication miniballs can be implanted in
the wall of a ductus or the medulla of an organ using a commercial
air pistol modified as described below in the section entitled
Modification of Commercial Airguns. When delivered through a
trajectory of acute angle, the miniball, usually around 0.4
millimeters in diameter, undercuts the intact tissue along a direct
path to the point of entry at the surface, and stuck in the
proteinaceous exudate liberated from the cells crushed, becomes
entrapped, making retrogression within the time until the miniball
has been completely absorbed improbable.
[2407] When placed subadventitially in a blood vessel where release
would result in an embolism, retreat can be prevented by the
application of a continuous or discontinuous coating of a solid
protein solder as described below in the section entitled Miniballs
Coated with a Heat-activated (-melted, -denatured) Tissue
Adhesive-hardener or Binder-fixative. Miniballs can be heated from
inside the lumen using the heat-windows and heat-generating radial
projection tool-inserts in the muzzle-head of the barrel-assembly.
That is, the muzzle-head used to place the medication miniballs
includes means for heat-denaturing (melting, flowing) this tissue
bonding agent as described in the sections herein on heat-windows
and `cooling` (temperature changing) catheters.
[2408] Miniballs that lack a ferrous core, instead consisting
exclusively of medication, can be used as an alternative option for
the parenteral administration of medication where stenting is
uninvolved. The procedure for the insertion of miniballs (as
opposed to medication stays) completely transluminal, entry at the
body surface (to place a stent-jacket) is uninvolved, and magnetic
tractive force as might cause a ductus wall to fail by intra- or
interlaminar separation (delamination) is thus uninvolved as well.
However, the diseased ductus wall may lack strength without the
application of force, which longitudinal, could allow overshots
that would misplace the medication, and radial, could allow
perforations where the absence of a prepositioned stent-jacket
would also mean that a protective barrier was lacking.
[2409] As to the intrinsic strength of the ductus wall without
regard to the application of tractive force, the consequences of
misplacement due to excessive travel through a weakened or
separated wall, such as medicating healthy tissue that could result
in a sum overdose, should determine whether the preliminary test
described below in the section entitled In Situ Test upon
Endoluminal Approach for Intra- or Inter-laminar Separation
(Delamination) is conducted. That a stent-jacket will not have been
prepositioned to prevent a perforation, or a double-wedge lined
stent-jacket to prevent a perforation or a rebound into the lumen,
recommends conducting the test described below in the section
entitled In Situ Test on Endoluminal Approach for Susceptibility of
the Ductus Wall to Puncture, Penetration, and Perforation.
[2410] Spherules consisting of a core and concentric shells for
ballistic implantation in the walls of diseased arteries, for
example, can be produced using conventional methods in the
pharmaceutical industry to include pan tumble coating, centrifugal
extrusion, and spray-drying. For most formulations, the vibrational
nozzle technique affords superior exactitude of sphericity, which
is important for maintaining accurate control over the discharge
velocity from the barrel-assembly in proportion to the distance the
miniball must transit from the chamber of the airgun to the exit
port in the muzzle-head. In every case, medication or tablet
miniballs, with or without an encapsulated ferromagnetic or
radiation source seed core, must be given an outer coating that
will withstand the tangential shear stresses encountered in
transitting the barrel-tube.
[2411] In radial discharge barrel-assemblies, the barrel-tubes
consist of a fluroro or another low friction polymer, or are lined
with a fluroropolymer produced by coextrusion. The
crushing-strength, disintegration time, porosity, and friability of
tablets relating consistently (see, for example, de Jong, J. A. H.
2005. "Relations Between Tablet Properties," Pharmacy World and
Science 9(1):24-28), resistance to the smaller impact forces of
ordinary handling varies proportionally to the the strength
required to prevent miniball tablet fracture upon discharge.
Discharge and travel through the barrel-tube subject miniball
tablets to tangential shear forces that exceed those encountered by
tablets in ordinary handling.
[2412] To prevent surface fractures, much less overt breakage
during discharge, which could not only affect discharge but result
in the deposition of debris along the barrel-tubes that might lead
to jamming, miniball tablets are strongly compressed as true
spheres and may be additionally covered with a fracture-resistant
coating, such as an ester bond based bioabsorbable polymer,
typically polyglycolic acid, polyester, or poly (p-dioxanone),
which to present a low coefficient of friction is further coated
with N-laurin and L-lysine. Overlying the core-encapsulating layer
that imparts bioinertness in a miniball with a ferrous or
lanthanoid core, such as produced by means of gold
Microfusion.RTM., miniballs for intraductal stenting can be further
encapsulated with medication or contain an irradiating seed as a
core.
[2413] Irradiating core miniballs are usually conventional seeds
with titanium jackets typically lined with a ceramic but in
spherical form, that are used apart from stenting function, which
would necessitate the incorporation of ferrous material. Some
stenosed conditions of a ductus may recommend seeds containing
ferrous metal to alleviate the stenosis by means of encircling the
ductus with a stent-jacket and to pinpoint the sources of radiation
with the same material. A drug-releasing external layer can consist
of polylactic acid (Dev, V., Eigler, N., Fishbein, M. C., Tian, Y.,
Hickey, A., Rechavia, E., Forrester, J. S., and Litvack, F. 1997.
"Sustained Local Drug Delivery to the Arterial Wall via
Biodegradable Microspheres," Catheterization and Cardiovascular
Diagnosis 41(3):324-332), a sugar, starch, or syrup coating tumbled
to assure sphericity while heat-blown or freeze-dried (lyophilized,
cryodessicated).
[2414] The addition to implants of adverse tissue reducing
substances is addressed above in the section entitled Tissue
Acceptance of Ductus-intramural Implants. Neither a medicated
coating that encapsulates and is meant to remain with the miniball
until implanted nor the fixative cornstarch, rice starch, other
syrup, molasses, acacia, methyl cellulose, povidone (polyvidone,
polyvinyl pyrrolidone, PVP), or gelatin used to position the
miniball in the ring-hole may be friable as to powder and leave a
particulate residue along the barrel to any significant degree.
Referring now to FIG. 27, some miniballs include all of the layers
represented in FIG. 20, to include a core 37 and additional layers
38 thru 40, to which is now further added an outermost coating 41
representing a drug-delivering, drug-eluting, or radiation-emitting
medium.
[2415] When subjacent layer 40 is a coating of tantalum for
enhanced radiopacity, adding a medicated or irradiative outermost
coating 41 does not annul this property. Within the overall range
for its diameter, adjusting the relative thickness, or varying the
relative diameter, of the five layers allows a miniball of
specified diameter to be given a specified mass or magnetic
susceptibility. Miniballs implanted in arteries can be medicated
with, for example, antithrombogenic, anti-inflammatory, or
antiseptic medication to reduce the risk and the severity of abrupt
closure by spasmodic reflex to ballistic implantation. The addition
in manufacture to an irradiating seed with a metallic, such as
titanium, outer jacket of concentric shells containing medication
by means of air-suspension is limited by the mass of the
miniball.
[2416] Serious complications have been associated with drug-eluting
intraductal stents. Often introduced as secondary endoluminal
stents to reduce the reocclusion of a stent placed earlier,
time-release drug-eluting stents have been implicated in clotting
and restenosis requiring surgery and may lead to death. However,
such complications as pain, rash, hives, itching, fever and changes
in respiration or blood pressure are likely the result of allergic
hypersensitivity to the specific drugs used. Such reactions are
maximized when the stent is in the bloodstream, and when intended
for local absorption rather than entry into the circulation, the
blood level of the drug obtained from an extraluminal stent can be
reduced to subclinical. A magnetized miniball, or miniball-magnet,
differs from a miniball in having a core made of magnetized
material, usually sintered neodymium iron boron rather than iron,
steel, alnico, or alternative ceramics.
[2417] Owing to the relatively poor magnetic efficiency of a
spherical contour, such miniballs must be somewhat larger for a
given application than the equivalent ferromagnetic miniball that
is attracted to a magnet. Unlike alternative magnets, which are
mounted to an organ or vessel surface, a miniball-magnet like any
miniball, can be implanted in deep tissue as well as coated with
additional layers for the immediate or time-delayed delivery of
medication. The crushing of cells along the trajectory of the
miniball liberates the substantially aqueous protoplasmic contents
to dissolve this outer coating releasing the medication, which may
be an antibiotic, anti-inflammatory, or contain a particle or gamma
ray-emitting radioactive isotope, into the surrounding tissues and
bloodstream. Provided the stent-jacket or substitute magnetic field
is applied, the fluid state at the trajectory terminus also allows
magnetized miniballs to roll around into tractive orientation.
[2418] Such medication can be analgesic, antipyretic,
anti-inflammatory; antibiotic; platelet blocking, anticoagulative,
emit radiation, or some combination of these. There is some
evidence to indicate that especially where the implants are outside
the lumen, an outer coating of polylactide-co-sigma-caprolactone
copolymer eluting paclitaxel, sirolimus, or dactinomycin, for
example, would make possible sustained delivery to suppress
neointimal hyperplasia for months after implantation and beyond the
time for delivery of the drug to have been completed and the
polymer to have dissipated (Drachman, D. E., Edelman, E. R.,
Seifert, P., Groothuis, A. R., Bornstein, D. A., Kamath, K. R.,
Palasis, M., Yang, D., Nott, S. H., and Rogers, C. 2000.
"Neointimal Thickening after Stent Delivery of Paclitaxel: Change
in Composition and Arrest of Growth over Six Months," Journal of
the American College of Cardiology 36(7):2325-2332.
[2419] The layers in a miniball must be capable of sustaining the
forces of expulsion without a loss in medical efficacy. This
includes a hard, smooth, and spherical outer coating that avoids
rolling resistance at curves dictated by the anatomy and
nevertheless dissolves as required. Layers outside the bioinert
layer that isolates the ferromagnetic core must thwart fracture,
crushing, and deformation while disintegrating as desired. If the
material of the layer cannot be made to the mechanical standards
required, then intervening layers or adjuvants must be added.
Unless sufficient hardness can be imparted to or about each added
layer, implants that contain the same sequence of layers must be
incorporated into and force the use of stays rather than
miniballs.
[2420] A preferred method for incorporating medication for
timed-release in the sugar-based outer coating of medicated
minibals is by liquid feed micro-encapsulation as may be produced
using apparatus available from the Sono-Tek Corporation, Milton,
New York. Depending upon the application, miniballs may be coated,
as with ion exchange resins, for example, not just to deliver
medication or radiation but to minimize the embologenicity of the
metal surface. In order not to affect the penetration
characteristics of the miniball in any significant way, such added
coats must be hard.
[2421] Improved acceptance by the ductus of the miniball and stay
implants described herein can be obtained by coating these with
phosphorylcholine (Goreish, H. H., Lewis, A. L., Rose, S., and
Lloyd, A. W. 2004. "The Effect of Phosphorylcholine-coated
Materials on the Inflammatory Response and Fibrous Capsule
Formation: in Vitro and in Vivo Observations," Journal of
Biomedical Materials Research. Part A 68(1):1-9; Chen, C., Lumsden,
A. B., Ofenloch, J. C., Noe, B., Campbell, E. J., Stratford, P. W.,
Yianni, Y. P., Taylor, A. S., and Hanson, S. R. 1997.
"Phosphorylcholine Coating of ePTFE Grafts Reduces Neointimal
Hyperplasia in Canine Model," Annals of Vascular Surgery
11(1):74-79; Whelan, D. M., van der Giessen, W. J., Krabbendam, S.
C., van Vliet, E. A. Verdouw, P. D., Serruys, P. W., and van
Beusekom, H. M. M. 2000. "Biocompatibility of Phosphorylcholine
Coated Stents in Normal Porcine Coronary Arteries," Heart
83(3):338-345).
[2422] Recent evidence indicates that a coating of zinc oxide,
especially in the form of nanorods, moderates an inflammatory
(immune) response (see, for example, Zaveri, T. D., Dolgova, N. V.,
Chu, B. H., Lee, J., Wong, J., Lele, T. P., Ren, F., and
Keselowsky, B. G. 2010. "Contributions of Surface Topography and
Cytotoxicity to the Macrophage Response to Zinc Oxide Nanorods,"
Biomaterials 31(11):2999-3007). Hydrogel polymers incorporating
phosphorylcholine can be used as a bioinert medium for this
medication (Lewis, A. L. 2006. "PC [Phosphorylcholine] Technology
as a Platform for Drug Delivery: From Combination to Conjugation,"
Expert Opinion on Drug Delivery 3(2):289-298.
[2423] V4. Medication-Coated Miniballs, Stays, and Prongs with a
Heat-Activated (-Melted, -Denatured) Tissue Adhesive-Hardener or
Binder-Fixative
[2424] Medication and stenting miniballs and stays can be
concentrically coated with drugs and other therapeutic substances,
such as adhesives, antiswelling agents, and drug resistance
reversal agents. Intraparietal failure as the result of
intralaminar or interlaminar separation is an eventuality that must
always be considered, and when confirmed by testing, measures taken
to prevent this outcome. Even when the disease process does not
dispose the ductus thus, the very introduction of the implant can.
Stays coated with a heat-activated tissue adhesive-hardener or
binder-fixative such as a continuous or discontinuous solid protein
solder layer about each stay to be melted once placed are discussed
above under the section entitled Stays Coated with a Heat-activated
(-melted, -denatured) Tissue Adhesive-Hardener. Such use is most
effective applied to wide stays. The same solder is used to enclose
miniballs.
[2425] When separation within the tissue of the ductus wall
discovered through the test provided below in the section entitled
In Situ Test on Extraluminal Approach for Intra- or Inter-laminar
Separation (Delamination) indicates that:
[2426] a. Miniballs would be stopped only once having reached an
outer tissue layer, which absorbing the force of impact by outward
displacement, would separate from the subjacent layer allowing a
miniball to insinuate itself within this space and continue
traveling down through the wall along the inner surface of the
outer layer to stop far distad of the target location, or that
[2427] b. Intraparietal miniballs and the tissue of the ductus wall
situated radially outward from the miniballs would be retracted by
the stent-jacket bar magnets leaving the tissue axial (closer to
the ductus central axis, adluminal) to the miniballs, hence, the
stenosed or collapsed lumen unaffected, or that
[2428] c. A less than severe malacia of the layers radially outward
of the implants would allow the gradual penetration of the implants
toward the stent-jacket magnets, that is, radial migration outwards
until the implants released the layers bounding the lumen if not
perforated the ductus, which phenomenon is referred to herein as
pull-through.
[2429] Then stays with an outer coating of a solid protein solder
should be used instead, or using miniballs, the stent-jacket must
be positioned prior to initiating discharge as discussed in the
sections entitled Sequence of Stent-jacket Placement and
Implantation and Double-wedge Stent-jacket Rebound-directing
Linings, and depending upon the results of the test upon
extraluminal approach, the additional precaution is taken of using
miniballs having an outer layer of solder less any coating
thereupon, such as an antibiotic that does not detract from
adhesion to the surrounding tissue or a lubricant that is
dissipated at or below the denaturation temperature. Medication
that withstands the temperature at which the solder denatures can
be incorporated into the solder or a subjacent coating.
[2430] The test upon extraluminal approach in anticipation of
implanting stays should be applied before and after implanting a
single test stay. The test can also reveal the need to use stays
coated with an adhesive-hardener and the amount of time that the
particular solder will take to achieve initial set under heat until
the stent-jacket can be placed. Such is not necessary with
miniballs, hence with endoluminal approach testing, because with
miniballs, it is possible to place the stent-jacket prior to
intiating ballistic implantation. While unable to contend with
malacia, when the lumen is filled and under pressure, preplacement
of the stent-jacket as addressed below in the section entitled
Sequence of Stent-jacket Placement and Implantation is usually
sufficient in itself to reduce a separation.
[2431] Discharged at high enough of a velocity, a miniball will
perforate entirely through the ductus wall regardless of a lack of
cohesion within or between tunics or layers within the wall, an
exception being those portions of the trachea subjacent to annular
ligaments. At lower velocities, however, the miniball will pull
apart and insinuate itself between layers in the wall of the ductus
susceptible to separation. With miniballs, when the layers within
the wall have been ascertained as prone to separate, the inter- or
intralaminar failure or insinuation and continued travel distad of
a miniball, along with the prevention of an eventual perforation,
and/or the need to suppress a pulse that interferes with
implantation, are among the reasons for prepositioning a snugly
fitting stent-jacket prior to initiating discharge.
[2432] A ductus wall judged too malacotic to resist the eventual
pull-through of implants under the tractive force exerted by a
magnetic stent-jacket even when the implants have been
solder-coated and heated is not a suitable candidate for treatment
with the aid of intraparietal implants as described herein. For
ductus that are not so weakened, plain or solid protein
solder-coated stays, addressed below in the section entitled
Arcuate Stent-stays (Stays, Stent-ribs, Ribs) for use with
stent-jackets which present 1. A much larger surface area parallel
to the ductus and thus better able to resist outward traction, 2.
Able to deliver solder over a correspondingly larger area, and 3.
Optionally coated with cyanoacrylate cement over the entire upper
surface, will be more resistive to gradual pull-through than
miniballs even solder-coated when not densely positioned.
[2433] While the application of cyanoacrylate cement contributes
some additional strength, even when coated over the entire upper
surface, stays are not dependent upon cyanoacrylate cement for
intraparietal stabilization, but rather upon the solid solder
adhesive coating over the entire surface. The cyanoacrylate, much
of which is `squeegeed` away upon incising the ductus, coats the
upper surface of the adventitia or fibrosa and is intended
primarily to seal the stay entry incision. That miniballs cannot be
coated with cyanoacrylate cement in addition to a coating of
antiplatelet or anticoagulant containing solder upon arrival is not
a significant detraction.
[2434] Cyanoacrylate cement is never needed to seal the point of
entry puncture wounds, and, while time-consuming without the
position assistance of a servocontrolled linear stage,
cyanoacrylate cement can be injected through a service-catheter
passed down a free barrel-tube used as a service-channel once the
miniballs have been implanted. Whether applied to stays or
miniballs, the cement must have an open time even when heated that
is sufficient to not encase the subjacent solder, which must be
heated, suitable retardants such as glacial acetic acid having been
specified in sections above, to include those entitled Description
of the Preferred Embodiments and Stays Coated with a Solid Protein
Solder Coating and Cyanoacrylate Cement. A miniball array such as
implanted with the aid of a multiple barrel-tube barrel-assembly
and positional control system is more quicly injected thus through
a hypointimal or hypoendothelial radial projection unit
tool-insert.
[2435] The distance that a tool-insert can be extended is
proportional to the diameter of the lumen, hence, the
barrel-assembly or radial projection unit catheter used, so that
one in the espohagus, for example, can inject well into the
submucosa. Coverage over a wider area of the lumen wall, whether to
inject a bonding agent in order to harden malacotic tissue or to
avert delamination, for example, or medication in order to cause
the wall to swell for easier implantation, for example, is
expedited through the use of a radial projection unit having a rear
supply line and fitted with a hypointimal or hypoendothelial
injection unit tool-insert, as shown in FIG. 56. When the tissue of
the ductus wall has become malacotic rather than reduced in
cohesion between its layers, preplacement of the stent-jacket only
will not decrease the propensity toward pull-through.
[2436] That the preplacement of a magnetic stent-jacket means that
magnetic traction will be exerted upon the miniballs immediately
upon insertion emphasizes the limitation of such an approach to the
prevention of perforation and intraparietal separation to the
exception of pull-through. Provided the additional precaution is
taken of using closely placed miniballs coated with a tissue
adhesive-hardener or fixative that is solid at room temperature but
denatures or melts and flows when heated, and then reaches initial
set quickly, a negligible degree of malacia may still allow the use
of a magnetic stent-jacket. This eventuality is due to the bonding
among adjacent miniball adhesive-hardener fields that acts to
divide the radially outward vector of magnetic traction between
this vector and a vector to either side.
[2437] Unlike stays, miniballs cannot be additionally coated prior
to implantation with cyanoacrylate cement, which setting more
rapidly the lower is the viscosity, cannot be provided in a
consistency sufficiently fluid at room temperature to act as a
lubricant that will not clog the barrel-tubes. The addition of
radiographic agent, tungsten powder, and/or glacial acetic acid can
extend the open time of a cyanoacrylate adhesive, but the
barrel-tubes are so small in gauge (typically 0.4 millimeters) that
the presence of any fluid within these would result in
obstruction.
[2438] While adhesives in contact with soft tissue are subject to
enzymatic and hydrolytic breakdown that makes these ephemeral in
adhesion retention, no more than two or so weeks is necessary to
positionally stabilize a small implant by fibrous encapsulation. A
separate (nonballoon) injection microcatheter passed down one of
the two barrel-tubes used in a two-way muzzle-head as described
below in the section entitled Service-channel Adhesive Delivery
Line used as a service-channel can be used to inject cyanoacrylate
cement about the miniball entry site following implantation (see,
for example, Miyachi, S., Izumi, T., Satow, T., Srivatanakul, K.,
Matsumoto, Y., and 3 others 2017. "Effectiveness of
Preradiosurgical Embolization with NBCA [N-butyl cyanoacrylate] for
Arteriovenous Malformations--Retrospective Outcome Analysis in a
Japanese Registry of 73 Patients (J-REAL study)," Neurointervention
12(2):100-109; Ellis, J. A. and Lavine, S. D. 2014. "Role of
Embolization for Cerebral Arteriovenous Malformations," Methodist
Debakey Cardiovascular Journal 10(4):234-239; Goto, K., Uda, K.,
and Ogata, N. 1998. "Embolization of Cerebral Arteriovenous
Malformations (AVMs) [arteriovenous malformations]--Material
Selection, Improved Technique, and Tactics in the Initial Therapy
of Cerebral AVMs," Neurologia Medico-chirurgica (Tokyo) 38
Suppl:193-199); however, a reduction in the number of barrel-tubes
reduces the rate of implant delivery. Proximity of the
cyanoacrylate to the heat used to melt a solder layer would
exacerbate its premature setting in any delivery line and following
parietal injection.
[2439] Moreover, cyanoacrylate cement is not amenable of dilution
or thinning through the use of a solvent, surfactant, or acetic
acid, for example, although the latter can be used to retard it in
initial set. Recovery electromagnets and antechambers are addressed
below in the section entitled Multiple Radial Discharge
Barrel-assemblies with One- to Four- or More-way Radial Discharge
Muzzle-heads. Access to the exterior of the ductus obstructed when
the stent-jacket has been placed previously, heat is applied to
flow the solder by the muzzle-head electromagnet windings or a
`cooling catheter` as addressed below in the section entitled
Cooling Catheters (Temperature-changing Catheters) snaked down the
barrel-assembly that is connected to the hot air outlet of a
nominally `cold` air gun.
[2440] According to the material of the base-tube, the preplaced
stent-jacket furnishes some heat containment or insulation value
which is usually sufficient to necessitate the use of an
endoluminal rather than extraluminal source of heat, but seldom
sufficient to justify preplacement in itself. When placed with the
aid of a positional control system, miniballs with a thicker
coating of solder can be positioned closely enough together that
upon heating, the tissue infused by the melted adhesive-hardener
fixative or binder from each, its respective adhesive-hardener
field, will merge with the field of the adjacent miniballs to cure
as a solid unit structure that is able further to resist migration,
to include by pull-through. For dealing with certain conditions,
the attainment of stability thus can be the primary purpose in
resorting to the use of machine controlled positioning.
[2441] Suitable plasticizers to reduce brittleness as might pose
resistance to intrinsic motility are dimethyl sebacate, di-n-butyl
sebacate, di-n-octyl phthalate, triethyl phosphate, triisobutyl
phosphate, tri(2-ethylhexyl) phosphate, tri-p-cresyl phosphate,
glyceryl triacetate, glyceryl tributyrate, diethyl sebacate
(Coover, H. W. Jr. and Fassett, D. W. 1973. "Surgical Method," U.S.
Pat. No. 3,759,264). Still other plasticizers were disclosed
earlier (see, for example, Joyner, F. B. and Coover, H. W. Jr.
1957. "Plasticized Monomeric Adhesive Compositions and Articles
Prepared Therefrom," U.S. Pat. No. 2,784,127; Shearer, N. H. Jr.
and Coover, H. W. Jr. 1957. "Mixed Alpha-cyanoacrylate Adhesive
Compositions, U.S. Pat. No. 2,776,232). When the condition of the
ductus is one of malacia rather than laminar separation, the
ability of the miniballs to resist ouward migration may necessitate
that the adhesive-hardener be allowed to fully cure before the
magnetic stent-jacket is placed.
[2442] When filled with solder that can be predicted with
reasonable confidence to gradually be replaced by continuous
tissue, and the surface of the miniball is textured to allow tissue
infiltration as will result in mechanical bonding, some residual
laminar separation may be acceptable. The object in allowing the
adhesive between miniballs to cure is to allow the formation of a
longitudinally extended unit that is better able to resist outward
migration. The thickness of the solid adhesive coating on the
miniballs determines the proximity with which the miniballs must be
placed to achieve such merger and unitization, and this in turn
will determine whether the use of a positioning control system is
needed to place the miniballs at the distance required.
[2443] Implanted transluminally, miniballs allow deferral to a
later procedure of stent-jacket placement, which is by laparoscopic
entry. When the restoration of patency is urgent, the use to treat
a malacotic ductus of miniballs coated with a protein solder having
a long curing time and thus forcing postponement in the placement
of the stent-jacket, is unacceptable. To restore patency
immediately, an anti-inflammatory such as a steroidal drug-eluting
absorbable endoluminal stent is inserted after placing the
miniballs. This endoluminal procedure as part of an endoluminal
procedure makes it possible to defer the laparoscopic entry wound
and placement of the stent-jacket for the period over which the
absorbable stent can be depended upon, which period will be far
longer than any required for the curing of an adhesive-hardener.
The patient can thus be given an period of months before the need
to perform the followup procedure.
[2444] V5. Heating Control Over Implants and Coated Implants, to
Include Miniballs, Stays, and Prongs
[2445] V5a. Heating of Implants and Coated Implants, to Include
Miniballs, Stays, and Prongs Using Implant-Passive Ductus-External
or Extrinsic Means
[2446] Heat can be used to accelerate the dissolution and/or uptake
of medication and/or a coating thereof, apply hyperthermic therapy,
and accelerate the dissolution of absorbable components, for
example. Magnetic or electromagnetic induction is used, the latter
familiar as induction heating. Implanted miniballs that include
medication, a bonding agent, or a tissue hardener, for example, can
be passively heated using heating elements in the muzzle-head, to
include heat-windows and radial projection unit tool-inserts,
described below. Stays are passively heated from outside the
adventitia, usually through the access wound. When the adventitia
is exposed and would not suffer heat injury, heating from outside
the ductus is possible. Entry through a small incision allows the
insertion of a heating probe that can heat the subadventitial
miniballs, stays, or prongs.
[2447] The Curie temperature is not reached and the implant not
demagnetized. Access from outside the ductus is suited to stays and
patch-magnets which are placed from outside the ductus and thus
necessitate an incision to be inserted in any event.
Ductus-external heating should not be confused with extracorporeal
or remote heating using electromagnetic energy as addressed above
in the section entitled Implants that Radiate Heat on Demand and
the section immediately following. However, implants such as
miniballs held within holding jackets, for example, which are
proximate to implants that incorporate extracorporeally excitable
elements can be warmed indirectly thus, the effect used, for
example, to cause or accelerate the dissolution of a medicinal
coating of a miniball or the dissolution of a medication
miniball.
[2448] V5b. Extracorporeal Energization of Intrinsic Means for
Radiating Heat from Within Medication Implants and Medication
and/or the Tissue Bonding-Coatings of Implants
[2449] All of the implants described herein, miniballs and stays in
particular, can incorporate materials formulated and/or configured
to allow these to generate and radiate heat from within by remote
control as well as release medication. Extracorporeal or remote
heating of the implants is mentioned above in the section entitled
Implants that Radiate Heat on Demand. Miniballs and stays can be
loaded with magnetically susceptible matter or magnetized to
support both magnetic drug-targeting and heating in either order
based upon the therapeutic objective (see, for example, Belyanina,
I. V., Zamay, T. N., Zamay, G. S., Zamay, S. S., Kolovskaya, O. S.,
and 13 others 2017. "In Vivo Cancer Cells Elimination Guided by
Aptamer-functionalized Gold-coated Magnetic Nanoparticles and
Controlled with Low Frequency Alternating Magnetic Field,"
Theranostics 7(13):3326-3337; Zamay, T. N., Zamay, G. S.,
Belyanina, I. V., Zamay, S. S., Denisenko, V. V., and 15 others
2017. "Noninvasive Microsurgery Using Aptamer-functionalized
Magnetic Microdisks for Tumor Cell Eradication," Nucleic Acid
Therapeutics 27(2):105-114; Vegerhof, A., Barnoy, E. A., Motiei,
M., Malka, D., Danan, Y., Zalevsky, Z., and Popovtzer, R. 2016.
"Targeted Magnetic Nanoparticles for Mechanical Lysis of Tumor
Cells by Low-amplitude Alternating Magnetic Field," Materials
(Basel, Switzerland) 9(11). pii: E943; Kobayashi, T. 2011. "Cancer
Hyperthermia Using Magnetic Nanoparticles," Biotechnology Journal
6(11):1342-1347; Ivkov, R., DeNardo, S. J., Daum, W., Foreman, A.
R., Goldstein, R. C., Nemkov, V. S., and DeNardo, G. L. 2005.
"Application of High Amplitude Alternating Magnetic Fields for Heat
Induction of Nanoparticles Localized in Cancer," Clinical Cancer
Research 11(19 Part 2):7093s-7103s).
[2450] Miniballs and stays can be made that include a single
medication, concentric layers of medication, or a single or
multiple layers of medication that include a ferromagnetic or a
radiation-emitting core, and heat used to effect or to accelerate
the release of each layer, which if including magnetically
susceptible matter, can also be magnetically targeted or spread.
The same or different magnetically susceptible matter can be
incorporated into the core or included in a matrix in the core or
in layers surrounding the core, and any or all of these coated to
codetermine with the matrix the temperature at which each will
disintegrate. When the core of a miniball, for example, is
constituted to radiate heat, applying successive concentric layers
of medication or other therapeutic substances in melting point
sequence moving outward from the core with that lowest outermost
will cause that substance to be released first, with those beneath
released in melting point sequence.
[2451] Cores and layers formulated to break down at a prescribed
temperature can also serve to accelerate the release and uptake of
the drug released or the action of a therapeutic substance. That
separate miniballs can release substances to act upon one another
and affect tissue individually or together is considered obvious.
Intrinsic heat radiation that necessitates the incorporation of
nonabsorbable elements is suitable for nonabsorbable implants and
nonabsorbable implants with absorbable coatings, such as of
medication. When nonabsorbable elements must be included for use in
the bloodstream, then impasse-jackets, addressed above in the
sections entitled Concept of the Impasse-jacket and Miniball and
Ferrofluid-borne Particle-impassable Jackets, or Impasse-jackets
are used to trap any magnetically susceptible nonabsorbable
residue.
[2452] Medication introduced upstream from an impasse-jacket and
suspended by the jacket in the lumen can incorporate drug carrier
nanoparticles that allow both the remote release by heating and
targeting of medication, for example. If necessary (which should be
seldom) the residue is then extracted from the impasse-jacket with
the aid of an external electromagnet, as addressed above in the
section entitled Miniball and Ferrofluid-borne Particle-impassable
Jackets, or Impasse-jackets and below in the section entitled Use
of an External Electromagnet to Assist in Mishap Recovery. To
assure retrievability in the event of a mishap, even medication
miniballs and stays contain magnetically susceptible matter, if
slowly absorbable, of iron powder, if absorbable or safely
assimilable in the small amounts involved, of superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder.
[2453] When a miniball, stay, or other implant incorporates
magnetically susceptible matter, the alternating magnetic field
produced by a high power magnetic resonance machine or an
alternating magnetic field applicator (Johannsen, M., Thiesen, B.,
Wust, P., and Jordan, A. 2010. "Magnetic Nanoparticle Hyperthermia
for Prostate Cancer," International Journal of Hyperthermia
26(8):790-795; Latorre, M. and Rinaldi, C. 2009. "Applications of
Magnetic Nanoparticles in Medicine: Magnetic Fluid Hyperthermia,"
Puerto Rico Health Sciences Journal 28(3):227-238) can be used to
heat that matter such that intervening tissue beyond the zone of
the heat radiated is unaffected. In this way, the core or
layer-incorporated nanoparticles or microspheres allow control from
outside the body over the release of medication from each layer.
Any of the implants described herein, to include miniballs, stays,
and prongs can be constituted to be heated by placing the patient
in the alternating magnetic field, to include that of a high power
magnetic resonance machine.
[2454] The heating of implants during imaging is normally
considered from the standpoint of burn avoidance (see, for example,
Maffei, E., Calcagnini, G., Censi, F., Triventi, M., and Bartolini,
P. 2010. "Numerical Model for Estimating RF-induced Heating on a
Pacemaker Implant during MRI: Experimental Validation," Institute
of Electrical and Electronics Engineers Transactions on Biomedical
Engineering 57(8):2045-2052; Busch, M. H., Vollmann, W., and
Gronemeyer, D. H. 2006. "Finite Volume Analysis of Temperature
Effects Induced by Active MRI Implants: 2. Defects on Active MRI
Implants Causing Hot Spots," Biomedical Engineering Online 5:35;
Leon-Villapalos, J., Kaniorou-Larai, M., and Dziewulski, P. 2005.
"Full Thickness Abdominal Burn following Magnetic Resonance Guided
Focused Ultrasound Therapy," Burns 31(8):1054-1055; Ruschulte, H.,
Piepenbrock, S., Munte, S., and Lotz, J. 2005. "Severe Burns during
Magnetic Resonance Examination," European Journal of
Anaesthesiology 22(4):319-320; Busch, M. H., Vollmann, W., and
Gronemeyer, D. H. 2005. "Finite Volume Analysis of Temperature
Effects Induced by Active MRI Implants with Cylindrical Symmetry:
1. Properly Working Devices," Biomedical Engineering Online
4(1):25; Karoo, R. O., Whitaker, I. S., Garrido, A., and Sharpe, D.
T. 2004. "Full-thickness Burns Following Magnetic Resonance
Imaging: A Discussion of the Dangers and Safety Suggestions,"
Plastic and Reconstructive Surgery 114(5):1344-1345; Smith, C. D.,
Nyenhuis, J. A., and Kildishev, A. V. 2001. "Health Effects of
Induced Electrical Fields: Implications for Metallic Implants, in
Shellock, F. G. (ed.), Magnetic Resonance Procedure: Health Effects
and Safety, Boca Raton, Fla.: Chemical Rubber Company Press, pages
393-414).
[2455] Heating as the result of placing heat-intolerant implants in
a high intensity alternating magnetic field is here used
intentionally. Incorporating iron oxide, cobalt, iron, or
cobalt-iron nanoparticles into the core or layers of a miniball,
for example, improves the heating effect. A magnetic field
alternated at radio frequencies can heat an implant containing such
material through eddy-current induction, superparamagnetism, and
Stoner-Wohlfarth magnetization reversal. When the viscosity of the
matrix permits, alignment with the alternating magnetic field
additionally exerts a heating effect, and an alternating electrical
current will be induced in an implanted object that incorporates
conductive wire.
[2456] Of these mechanisms for remote heating in an alternating
magnetic field, some act on magnetically susceptible particles;
burns, however, result from the induction of electrical current in
conductive wire-shaped components such as artificial pacemaker
leads when placed in a magnetic field alternated at radio
frequency, especially when these components participate in a closed
circuit (see, for example, Yamazaki, M., Yamada, E., Kusumi, K.,
Sahara, T., Higashida, M., and Motozuka, M. 2008. "Investigation of
the Local Heating caused by a Closed Conducting Loop at Clinical MR
Imaging: Phantom Study," [in Japanese; English abstract at
http://www.jstage.jst.go.jp/article/jjrt/64/7/883/_pdf], Nippon
Hoshasen Gijutsu Gakkai Zasshi 64(7):883-885).
[2457] To deliberately intensify the heating effect, miniballs and
stays incorporate electrically conductive material to form of a
closed circuit, for example. The miniballs or stays are constituted
so that these mechanisms singly or in combination make it possible
to bring the implant or its currently outermost layer to the
temperature desired. When the miniball, stay, or its outer layer
consists in whole or in part of a protein solder devised to
denature (melt, flow) at a low enough temperature to avoid injury
to tissue, the nanoparticles or microspheres incorporated into the
solder act to melt the solder or if passively heated by an outside
source as addressed above in the section entitled Heating of
Implants and Coated Implants, to Include Miniballs, Stays, and
Prongs Using Implant-Passive Ductus-external or Extrinsic Means as
well, then accelerate its melting from outside the body.
[2458] The same nanoparticles that in an alternating magnetic field
serve to heat the matrix can support magnetic drug or other
therapeutic substance targeting in the field of a strong hand-held
electromagnet or the B.sub.0 field of a magnetic resonance machine,
as addressed below in section X2c entitled Stereotactic Arrest and
Extraction of a Circulating, Dangerously Mispositioned, or
Embolizing Miniball. While miniballs and stays must incorporate
sufficient magnetically susceptible matter to allow emergency
recovery if necessary, miniballs and stays used to implant
medication consist predominantly of absorbable matter. A residue
absorbed over time if ever is trapped and can be extracted.
[2459] As nonabsorbable, larger miniballs and stays used for
long-term or permanent magnetic stenting or to emit radiation can
alternatively or additionally incorporate a resonant circuit which
is energized to generate heat when placed in magnetic field
alternating at radio frequency. Implanted miniballs incorporating a
resonant circuit can be heated from outside the body with an
external source of radiofrequencies (see, for example, Niwa, T.,
Takemura, Y., Inoue, T., Aida, N., Kurihara, H., and Hisa, T. 2008.
"Implant Hyperthermia Resonant Circuit Produces Heat in Response to
MRI Unit Radiofrequency Pulses," British Journal of Radiology
81(961):69-72, available at
http://bjr.birjournals.org/cgi/content/ful1/81/961/69); however,
with ferromagnetic components implanted, radiofrequency generation
can be obtained from the transmit only coil of a nuclear magnetic
resonance machine.
[2460] Once refined to allow an increase in temperature greater
than 12.6 degrees centigrade (55 degrees Fahrenheit), this
capability will allow heating a miniball with a deeply textured
undercut surface and an outer coating of a protein solder or solder
and medication to denature (flow) the solder about it to secure the
miniball in position against the constant if slight pull of the
magnetic stent-jacket. The solder is then gradually replaced by
infiltrating tissue to perpetuate the positional stability. The
incorporation of nanoparticles in layers and/or coatings that
envelope layers of medication expand the differential control by
layer that can be exerted. The incorporation into miniballs, stays,
and patch-magnets, for example, of extracorporeally energizable
elements also pertains to impasse-jackets, wherewith miniballs held
by the jacket and the encircled segment of the ductus, for example,
can be heated.
[2461] For this purpose, the miniball will usually itself
incorporate the extracorporeally heatable element, indirect heating
by a surrounding stent or holding jacket being less effective. The
resonant response to a time-varying magnetic field can be used to
cause nanoparticles coating on a polymeric matrix to release heat
into the surrounding tissue where the warming effect can be used to
warm the treatment ductus, or accelerate dissolution and uptake of
a drug, or the melting of a protein solder, for example (Namdeo,
M., Saxena, S., Tankhiwale, R., Bajpai, M., Mohan, Y. M., and
Bajpai, S. K. 2008. "Magnetic Nanoparticles for Drug Delivery
Applications," Journal of Nanoscience and Nanotechnology
8(7):3247-3271; Bastus, N. G., Puntes, V. F., Amigo, R., Batlle,
X., Labarta, A., Kogan, M. J., Araya, E., Grillo-Bosch, D., Giralt,
E., and Turiel, A. 2006. "Nanoparticles: Local And Remote Energy
Sources," European Material Research Society, Spring Meeting,
Symposium A, 29 May-2 June, Nice, France, text at
http://www.nanospain.org/Workshop2/Files/Orales/Nanobiotechnology/Gomez_N-
eus.pdf, slides at
www.nanospain.org/Workshop2/Files/Presentations/GomezBastus_Neus.pdf;
published as Bastus, N. G., Kogan, M. J., Amigo, R., Grillo-Bosch,
D., Araya, E., Turiel, A., Labarta, A., Giralt, E., and Puntes, V.
F. 2007. "Gold Nanoparticles for Selective and Remote Heating of
.beta.-amyloid Protein Aggregates," Materials Science and
Engineering: C. Materials for Biological Applications 27(5-8):
1236-1240; Alexiou, C., Jurgons, R., Seliger, C., and Iro, H. 2006.
"Medical Applications of Magnetic Nanoparticles," Journal of
Nanoscience and Nanotechnology 6(9-10):2762-2768). Nanoparticles
can also be used to obtain different resonant responses from layers
or shells of medication.
[2462] Nanoparticle-incorporating miniballs, stays, and coatings
applied to any of the implants described herein to allow the
noninvasive induction and radiation of heat can release drugs for
magnetic drug-targeting, enabling multimodal ductus-intramural
treatment (see, for example, Chen, B., Wu, W., and Wang, X. 2011.
"Magnetic Iron Oxide Nanoparticles for Tumor-targeted Therapy,"
Current Cancer Drug Targets 11(2):184-189; Chen, Y. and Chen, B. A.
2010. "Application and Advancement of Magnetic Iron-oxide
Nanoparticles in Tumor-targeted Therapy," Chinese Journal of Cancer
29(1):125-128 (in English as "Application and Development of
Magnetic Iron-oxide Nanoparticles in Tumor-targeted Therapy," at
http://www.cjcsysu.cn/ENpdf/2010/1/118.pdf); Purushotham, S.,
Chang, P. E., Rumpel, H., Kee, I. H., Ng, R. T., Chow, P. K., Tan,
C. K., and Ramanujan, R. V. 2009. "Thermoresponsive Core-shell
Magnetic Nanoparticles for Combined Modalities of Cancer Therapy,"
Nanotechnology 20(30):305101; Peng, X. H., Qian, X., Mao, H., Wang,
A. Y., Chen, Z. G., Nie, S., and Shin, D. M. 2008. "Targeted
Magnetic Iron Oxide Nanoparticles for Tumor Imaging and Therapy,"
International Journal of Nanomedicine 3(3):311-321). Medication
and/or radiation miniballs and stays can incorporate any of
differently constituted nanoparticles.
[2463] Unlike the magnetic targeting of a ferrofluid (Alexiou, C.,
Arnold, W., Klein, R. J., Parak, F. G., Hulin, P., Bergemann, C.,
Erhardt, W., Wagenpfeil, S., and Lubbe, A. S. 2000. "Locoregional
Cancer Treatment with Magnetic Drug-targeting," Cancer Research
60(23):6641-6648), by secondary accumulation at the treatment site,
delivery is to the target ab initio. While intrusive, implantation
is preferable when the site must be exposed. The application of
extracorporeal shock wave lithotripsy to the disintegration of
miniballs or stays containing medication that had previously been
implanted in the wall of a lumen is limited by the need to avoid
dislodgement, delamination, or perforation into the lumen or
through the adventitia.
[2464] V6. Chemical Control Over Implants and Coated Implants, to
Include Miniballs, Stays, and Prongs
[2465] Miniballs, impasse-jackets, and stays can incorporate drugs
or other therapeutic substances for prepositioning in locations not
previously accessible, to target a small surrounding area at a
later date if and when the need for that substance or substances is
confirmed. The encapsulating layer, or a specially prepared drug
that remains physiologically inactive or metabolically inert until
converted after implantation does not require encapsulation, or
both are made nonbiodegradable or inert in the metabolic milieu
until a second, or if both, two additional exogenous substances,
are brought into contact with it. That is, unless the medication
and/or other therapeutic substance can itself prepared in a
nonbiodegradable or metabolically inert form, it is protected
within a nonbiodegradable or metabolically inert capsule. In
exceptional cases where premature or unnecessary activation of the
drug would be harmful, a metabolically inert pharmaceutical is
additionally encapsulated within a metabolically inert shell. More
specifically, such drugs include:
[2466] 1. Any prior art solid or liquid drug or therapeutic
substance or combinations thereof within an endogenously
(metabolically) inert (nondisintegratable, indissoluble,
nonbiodegradable) surrounding outer chemically isolating capsule or
shell that must be exposed to a biocompatible exogenous
(nonmetabolic) solvent or disintegrating chemical such as an
enzymatic breakdown agent to expose its contents;
[2467] 2 A special class of nonencapsulated prodrug in solid form
that remains endogenously (metabolically) inert and physiologically
inactive until brought into contact with and converted by an
exogenous biocompatible solvent or disintegrating chemical such as
an enzymatic breakdown agent.
[2468] 3. Such a prodrug, proenzyme (zymogen), protein precursor
(pro-protein, pro-peptide) or prohormone, such as precursory
prednisolone, for example, that would be injurious if released
prematurely or unnecessarily can be additionally encapsulated as
described, whereupon one exogenous dissoluting agent must be
introduced to disperse the encapsulating layer and another to
activate the contents.
[2469] A second substance either dissolves the capsule surrounding
the conventional drug, or activates an unencapsulated prodrug, or
if an encapsulated prodrug, then the next added or second substance
disintegrates the capsule exposing the inert prodrug with the third
substance added to activate it. Any type drug mentioned in the
section above entitled Field of the Invention is included. When
formulated for such use, such prodrugs and/or other therapeutic
substances in miniballs, or in the concentric layers thereof, or
microspheres suspended in the bloodstream by impasse- and
exceptionally, by more strongly magnetized stent-jackets, for
example, are converted or supplemented and thus activated.
Different paired substances and the relative proportion of each
allow selective control in response to follow-up diagnostics.
[2470] While ordinarily delivered directly to the implant or
implants in the wall surrounding the gastrointestinal tract or
through the blood stream by oral administration, alternative routes
allow the amount of the activating or triggering substance or
substances to be less. Whether introduced through the bloodstream
or by direct injection, delivery can be through any lumen. The use
of heat directly applied or induced is addressed above in the
sections entitled Implants that Radiate Heat on Demand, Heating
Control over Implants and Coated Implants, to Include Miniballs,
Stays, and Prongs, among others. When direct or induced heat is
additionally used, the solvent can be encapsulated and released by
heating within the same or a neighboring implant.
[2471] Dissolution of the encapsulating layer can be accomplished
by nonmetabolic chemical dissolution with or without heat. The
placement in close formation of miniballs under machine control
allows a mix of miniball types for response to different aspects of
the disease process confronted. The dense spacing among implants
required to satisfy such a combination of desiderata is but one
circumstance that warrants the precision of discharge under machine
control. If the encapsulated substance is a conventional drug or
prodrug, then once the capsule has been disintegrated, the contents
are activated and dispersed in the conventional manner through
biotransformation, or spontaneous metabolic conversion. Preparation
thus of both physiologically active and prodrugs differs only in
requiring encapsulation within a material that only a biocompatible
solvent not found in the body will dissolve or an exogenous agent
will disintegrate.
[2472] The detailed formulation of paired encapsulating materials
and substances to disintegrate these exceeds the present scope. One
example for the use of medicinal implants as described is the site
of an atheroma where the release of antimitotic and
anti-inflammatory medication is best withheld until restenosing is
confirmed. Implants to release medication are addressed above in
the sections entitled Medicinal and Medicated Miniballs and Stays;
Absorbable and Nonabsorbable Circumvascular Jackets with Medicated
Linings; and Medication (Nonstent) Implants and Medication-coated
Miniballs, Implants, and Prongs, among others, with control over
release from outside the body addressed above in the section
entitled Extracorporeal Energization of Intrinsic Means for
Radiating Heat from Within Medication Implants and Medication
and/or the Tissue Bonding-coatings of Implants, among others.
[2473] Both encapsulated and solid prodrug miniballs described can
be prepositioned by suspension in the lumen by a holding jacket, or
miniballs or stays of like formulation infixed within the wall
surrounding the lumen. Suspended within a holding jacket, a drug
ferrobound to magnetically suseceptible particles will upon
disintegration of the miniball be drawn into the wall of the lumen,
whereas one ferro co-bound, that is, enclosed or compacted together
with but not uncleavably bound to the drug will be freed to flow
downstream with the susceptible matter needed for retention within
the holding jacket if small enough drawn into the ductus wall and
if too large to be drawn in, then held against the wall. Release of
an encapsulated prodrug of the kind indicated is achieved by a
solvent, liquefying agent, or converting enzyme for the
encapsulating layer, and another agent such as a converting enzyme
to convert the prodrug to the physiologically active state.
[2474] If and only if the second or second and third substances
would not be absorbed from the lumen into the ductus wall, a
miniball or stay prepositioned therein is accessed by injection
with an injection tool-insert. In this circumstance, unless the
triggering substances are to be added immediately (thus defeating
much of the advantage), access to the miniballs or stays would
necessitate a second procedure, although direct injection allows
the amount of the activating substance to be minimized relative to
alternative routes. In the gastrointestinal tract, suspension in a
holding jacket allows the second and/or third complementary
triggering substance to be introduced postprocedurally, and if
accessed through the oral route, has the additional benefit of
delivery at a later date simply by swallowing a pill.
[2475] Access to the vascular tree without the need to return to
the clinic is preferably oral but can be accomplished through a
subcutaneously implanted portal for a direct or central catheter.
Other system ductus are accessed directly by implanted catheter
with subcutaneous surface access portal. If intended to circulate,
the substance must enter the bloodstream; thus, any such substance
administered orally must pass through the gut as a ferrofluid, and
if not specifically targeting the liver, must pass through the
liver. While accomplished by injection or infusion without the need
for a second invasive transluminal procedure, the need for frequent
dosing recommends showing the patient how this is accomplished at
home; however, one-time parenteral delivery of a later activating
agent or agents is accomplished in the clinic.
[2476] Ideally, the activating substance is prepared as an orally
administered liquid which the patient instructed to take by mouth
at a set time and date following implantation. That treatment is
targeted with the systemic circulation substantially avoided even
when the nonimmunogenic activating substance or substances are
transmitted by the circulation allows drugs to be combined that
might produce adverse sequelae if not limited to a small area.
Magnetically susceptible matter in blood borne miniballs or
microspheres will be seized within the impasse- or stent-jacket so
that it is drawn against and into the lesion. A drug and/or
radionuclide bound to this matter will be drawn together with it,
whereas unbound, these will be liberated and carried forward in the
bloodstream leaving the magnetically susceptible matter within the
jacket. If exceptionally necessary, an impasse-jacket will allow
the accumulated magnetic matter to be extracted noninvasively, as
addressed above in the section entitled Concept of the
Impasse-jacket.
[2477] By contrast, removal from a stent-jacket which lacks an
extraction grid, is by means of a guidewire with a tip magnetized
strongly enough to overcome the pull of the jacket or the recovery
electromagnets in the muzzle-head of a radial discharge
barrel-assembly. Increasing the temperature of an implant by
placing the patient in a radio frequency alternating magnetic field
as may be used to disintegrate concentric layers of medication is
addressed in the preceding section. The coordinated use of heating
and the infusion, injection, or ingestion of activating substances
affords control over the release of each layer. Control encompasses
both the release and rate of release of drugs, therapeutic
substances, and exceptionally, radionuclides from miniballs,
layered miniballs, microspheres, and layered microspheres seized
from the luminal contents and held within entry impasse- or
stent-jackets.
[2478] Paired entry and exit-jackets, addressed above in the
sections entitled Field of the Invention and Concept of the
Impasse-jacket and below in the section entitled Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays, among others, are
used to designate (establish the limits of, denote, define,
outline) a particular segment of a ductus or an organ for
treatment. The exit jacket releases a counteractant or agent that
counteracts (reverses, neutralizes) the substance released by the
entry jacket by molecular cleavage, binding, inactivation, or
inverse agonist release. The various means for controlling the
release of substances from miniballs held in impasse-jackets afford
the ability to differentially control the release or rate of
release of an actant at the entry jacket and the counteractant at
the exit-jacket.
[2479] V7. Radiation-Emitting (Brachytherapeutic,
Endocurietherapeutic, Sealed Source Radiotherapeutic, Internal
Radiation Therapy) Miniballs
[2480] The ability to transluminally approach a level, that is, a
certain distance along a ductus that is a site of disease, and
infix within the lumen wall a discrete implant that emits radiation
and/or medication affords advantages over the prior art, in that to
accomplish a similar result, one previously had to introduce an
endoluminal stent that brought with it the several problems
discussed above. Of these, medical but not irradiating implants
could be absorbable. Miniball implants can consist entiely of
medication, which by concentric layering can be multiple, can
include a core that is an irradiating seed, and miniballs implanted
in adjacent relation can combine, separate, and alternate in
medication and radiation. Tantalum or comparably vivid markings at
the muzzle-port or ports is discussed elsewhere.
[2481] The placement of radiation-emitting seed miniballs by the
means described herein is not intended for transluminal
implantation of the prostate gland, which if introduced through the
urethra would injure the epithelium exposed to urine and could
injure the urethral verumontanum. Neither does ballistic
implantation allow the suturing together of seeds for positional
stability as does conventional needle insertion. When the
muzzle-head can be brought beyond the distal extremities of the
bronchi so that little more than manageable hemorrhaging would
result, use of this method may be given consideration. The
preparation of radiactive miniballs, whether for aeroballistic
discharge or for bonding between the lining and base-tube of a
stent-jacket, for example, is no part of the present invention and
can be accomplished by means such as those described in Good, R. R.
1994. "Endocurietherapy," U.S. Pat. No. 5,342,283, with
continuation-in-part Good, R. R. 2000. "Endocurietherapy," U.S.
Pat. No. 6,099,457.
[2482] Conventionally, higher dose-rate radiation is administered
either brachytherapeutically with an automated remote afterloader
machine or by external beam radiation (see, for example, Waksman,
R. (ed.) 2002. Vascular Brachytherapy, Hoboken, N.J.:
Wiley-Blackwell). However, provided seeds are spherical, any
barrel-assembly of matching gauge or caliber can be used to implant
ceramic-titanium encapsulated radioisotopes of such radioisotopes
(radionuclides) as cesium-131, iridium-192, bismuth-212, lead-212,
iodine-125, gold-198, phosphorus-32, ytterbium-169, yttrium-90, or
palladium-103 within the wall of a ductus. The primary object is to
allow implantation of seeds in the walls of ductus not previously
implantable thus and secondarily to allow the use of seeds that
deliver a higher dose-rate which can be withdrawn at will.
[2483] Moreover, because the same apparatus or in some instances,
an external hand-held electromagnet can be used to recover the
seeds, higher dose-rate seeds can be implanted for a period
determined on the basis of followup diagnostics and removed when
desired. No endoluminal stent present, radiation seeding pertains
to primary stenotic conditions best treated by highly localized
sources rather than to reducing the risk of in-stent restenosis.
The interstitial brachytherapeutic seeds required differ from those
currently made by Implant Sciences Corporation, Wakefield, Mass.,
IsoRay Medical Incorporated, Richland, Wash., North American
Scientific, Chatsworth, Calif., or C. R. Bard, Incorporated,
Covington, Ga. only in being spherical.
[2484] The forces generated by airgun expulsion in medical use do
not attain values as would jeopardize seed integrity as
conventionally manufactured, so that no additional precautionary
structural modifications to the seeds is required. Furthermore,
whereas low-dose-rate seeds have been considered unrecoverable, by
enclosing ferrous metal within the seeds, the recovery
electromagnets, which just in front of (distal to) the muzzle-ports
are immediately present to the implantation site, are present to
retrieve any seeds that should become mispositioned. Depending upon
the maximum diameter of the miniballs that can be used, the
spherical seeds may be further encapsulated within layers of
medication or sequentially time-released medication. In this
connection, and with respect to the pure medication miniballs, a
medical layer can contain a gamma-emitting isotope such as
indium-111 or molybdenum-99.
[2485] Conventional intraductal brachytherapy is compatible with
the use of a barrel-assembly. The intraductal brachytherapy
catheter is passed down the barrel-assembly (as is a cooling
catheter, addressed below in the section entitled Cooling Catheters
(Temperature-changing Catheters). The same applies to a
high-dose-rate source delivery catheter as controlled by an
automated afterloader. When performed with another catheter-based
procedure, radiation seeding by this means differs from intraductal
brachytherapy in not requiring the withdrawal of one catheter and
the introduction of another; only the extracorporeal rotary
magazine clip in the airgun requiring to be changed.
[2486] V8. Temporary (Absorbable) Ferromagnetic Miniballs and Other
Implants
[2487] In treating a temporary condition, when it is preferred that
the miniballs used with a temporary stent-jacket or patch-magnets,
magnet-jacket, or external magnet-jacket that will be removed when
no longer needed not remain within the ductus wall but dissipate,
the miniballs are made with superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder dispersed in an
absorbable matrix. Absorbable ferromagnetic miniball implants can
contain medication, a bonding agent, superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder for retrieval, a
radiation emitting seed, or any of these in combination. The matrix
can include or consist purely of medication. The absorbable
materials, mostly the same as those used for absorbable suture and
to make tissue engineering scaffolding are addressed above in the
section entitled Stent-jacket expansion insert materials having
relatively short breakdown times.
[2488] VI. Rotary Magazine Clips
[2489] FIG. 28 shows a seven-shot rotary magazine clip for use in a
single barrel radial discharge barrel-assembly, and FIG. 29 a
10-shot rotary magazine clip for use in a four barrel or four-way
radial discharge barrel-assembly. The single-shot rotary magazine
clip can be adapted for use in a four barrel or four-way radial
discharge barrel-assembly where only one barrel-tube is used, but
the reverse. The miniball-holes 42 in each clip have been numbered
for reference and do not appear on clips. The miniballs of each
shot-group or discharge complement can each have a hole in a
specially produced clip or a plug containing the smaller holes is
inserted into the clip holes of the clip as manufactured. A beveled
border surrounding each clip hole with the entry face directed back
toward the valve body assists to contain and concentrate the
propulsive against the miniballs.
[2490] The bevel is applied to the rim of the holes in the clip
whether the miniballs have separate holes or are inserted into the
clip hole as a group in a plug. The bevel edge is created by
machine taper-reaming or by using the taper at the end of a drill
bit in a drill press. Custom made clips include the bevel in the
mold. If made by removing material around the clip hole, the bevel
must not interfere with retention of the miniballs or the plug
containing the shot-groups. To provide a deeper depression with an
angled surround is readily accommodated in dedicated interventional
airguns as addressed below in the section on airgun; however, to
allow the use of thicker rotary clips or the placement of a beveled
collar surround about each clip hole necessitates increasing the
distance from the valve body outlet to the rear face of the clip,
which may be impracticable.
[2491] The rotary magazine clips are separately sealed in a sterile
airtight package and disposed of after use. An old and common
device, rotary magazine clips are mounted by means of an axial hole
at their center 43 to a hub or axle in the airgun and are rotated
by the indexing action of an arm or pawl that rises to engage the
circularly successive notches molded into the clip about its
periphery or outer edge and pushes against each notch seen in FIGS.
30 and 31 but on the reverse or back side of the views provided and
thus not seen in FIGS. 28 and 29) to obtain rotation as the sum of
these rotational increments. Reloading the airgun is accomplished
quickly, one rotary magazine clip pulled off the axle in the airgun
and another inserted in its place.
[2492] The rotary magazine clips used in the airguns to be
described are conventional in overall dimensions but situate one or
more, usually up to four, miniballs for discharge at a single time.
Barrel-assemblies which radially discharge eccentrically to treat
eccentric lesions are fed from the same kind of rotary magazine
clips with the changes in direction obtained by the course taken
within the barrel-tubes. To more axially direct the propulsive
force when the chamber is not airtight behind the barrel, and thus
reduce diagonal vectors from the gas entry portal at the back of
the chamber directed toward the rear of the slightly off-axis
miniballs that are otherwise concentric thereto, the back hole can
be drilled out to a larger diameter. Incorporation into the rotary
clip holes of a slight circumferential ridge midway from the front
to the back face prevents the miniballs from dropping out of the
rotary magazine into the barrel before discharge.
[2493] The addition of this ridge allows the Model 617X airgun made
by Maruzen Kabushiki Kaisha according to the specification of and
sold by the Daisy Outdoor Products Company to shoot either
miniballs or pellets, this model differing from the Model 622X of
the same maker only in caliber and the ability to shoot miniballs
as well as pellets. The rotary clips to be provided for use in an
interventional airgun are unique in the caliber of the miniballs to
be loaded. To spare the cost of preparing original molds to make
the rotary clips, those in manufacture can be adapted by inserting
a disk into the existing holes which contain the holes for the
miniballs. When all the miniballs to be discharged at the same time
are alike in mass, a slight midcircumferential ridge along the
internal surface of each hole may be used.
[2494] Another way to retain the miniballs in the holes until
discharge is to run povidone, cornstarch, syrup, molasses, acacia,
methyl cellulose, or gelatin into the groove formed between the
circumference of the miniball and the edge of the hole, allowing
the syrup to form a uniform layer by surface tension, which is then
freeze or quick dried by being passed under a heat lamp. Varying
the formulation of the syrup in concentration and ingredients, such
as sugars, starches, and the others just mentioned allows different
degrees of adhesion that allow the loading of miniballs that differ
in mass on the same rotary clip. Varying retentive adhesion
inversely as the mass of the miniballs to be discharged together
allows treatment of an eccentric distribution of lesions where some
areas pose greater resistance to penetration or may require
different medication in the form of an outer layer applied to the
miniballs.
[2495] VII. Barrel-Assemblies
[2496] VII1. Types and Capabilities of Barrel-Assemblies
[2497] VII1a. Types of Barrel-Assemblies
[2498] Barrel assemblies and airguns differ in capabilities and
suitability for a given procedure. To the extent possible, the
apparatus is devised to cover a range of applications; however, no
adjustment or attachment would allow a single apparatus to be used
for widely different procedures. Supplementary radial projection
units can be added to any barrel-assembly by ensheathment within a
combination-form radial projection catheter, for example, but a
given barrel-assembly must have a certain diameter, vary in radial
projection units if any, and incorporate or lack gas pressure
relief channels, for example. The functions involved not of the
kind ordinarily performed on an intermittent or incidental basis
during discharge implantation, combination-form barrel-assemblies
are usually ablation or ablation and angioplasty-capable and seldom
of the minimal ablation or angioplasty capability type.
[2499] Point to point diagnostic and therapeutic as well as
diagnostic use of barrel-assemblies is addressed below in the
section entitled Testing and Tests. Except for use in the
bloodstream where gas embolism must be avoided, combination-form
embodiments having an atherectomy cable running down the central
channel to the distal tip can be supplemented by a back-end plug-in
cold vaporization gas (carbon dioxide, nitrous oxide, or liquid
nitrogen) spray can or cartridge, triggered spray can models
CRYAC.RTM. and CRY-AC-3, available with an extension tip, supplied
by Brymill Cryogenic Systems, Ellington, Conn., for example, being
specially made for medical applications. The use of either heat or
cold to treat different lesions is thus made possible.
[2500] Unused barrel-tubes used as service channels and radial
projection unit ejection tool-inserts can eject contrast to confirm
revascularization, an angiorelaxant such as nitroglycerin to aid
passage, beta or calcium channel blockers, phosphorylcholine, and
any number of other drugs locally at the site to be implanted.
Barrel-assemblies can be classified into three essential
types--those incapable of ablation or angioplasty, those having
such capability only to the extent of serving during and as an
adjunct to discharge implantation, and those capable of an ablation
or angioplasty whether prior to and separately from or following
engagement in the airgun. Use apart from the airgun denotes
standalone or internal power and control rather than connection to
the power supply and use of a control panel on the airgun.
[2501] The latter two types are also distinguished as usable or not
usable in the bloodstream. Setting aside variability in diameter
within any given type, barrel-assemblies are better defined as
falling into one of eight classes, those more capable acceding to
additional function by adding to the components required in simpler
types. Those incapable of use independently of an airgun are:
[2502] a. Ablation and angioplasty-incapable, which include simple
pipes and radial discharge Barrel-assemblies which lack
heat-windows and radial projection units but must include a
miniball recovery electromagnet, or trap-magnet, which requires
connection to a power source. Radial discharge barrel-assemblies
permanently enclose the barrel-tube for frontoradial discharge, and
unlike simple pipe monobarrels, are not bendable.
[2503] b. Minimally or marginally ablation but not for use in the
bloodstream much less angioplasty-capable, which often include
heat-windows and radial projection units but do not require the
pressurized gas diversion channels to prevent the entry of gas into
the bloodstream (gas embolism), blood-grooves or blood-tunnels to
allow some blood to pass reducing the risk of ischemia, but may
include an embolic trap-filter as a backup dropped miniball
recovery device.
[2504] c. Minimally or marginally ablation-capable, which for use
in the bloodstream require gas embolism, thromboembolic, or
ischemia averting features, such as pressurized gas diversion
channels but are not angioplasty-capable. Such barrel-assemblies
may incorporate an embolic trap-filter as a backup dropped miniball
recovery device; an ablation and angioplasty-incapable
barrel-assembly, meaning one incapable of use when disengaged from
the airgun power source, when used in the bloodstream solely for
discharge, must still incorporate gas diversion channels and be of
radial discharge conformation.
[2505] d. Minimally or marginally ablation and angioplasty-capable,
which require gas embolism, thromboembolic, and ischemia averting
features, such as pressurized gas diversion channels and an embolic
trap-filter. Ensheathment of a minimally ablation or ablation and
angioplasty-capable barrel-assembly within a combination-form
radial projection catheter of matching size effectively converts
the barrel-assembly into a bipartite minmally ablation or ablation
and angioplasty-capable barrel-assembly. It does not convert a
minimally capable barrel-assembly into a fully capable one, because
such a barrel-assembly draws power and is controlled from the
airgun through terminal contacts in the end-plate such that removal
from the airgun disconnects the barrel-assembly from its source of
power. For clarity and to minimize human error, power and control
are kept with the component served, so that a minimally capable
barrel-assembly is not powered or controlled from the projection
catheter power and control housing.
[2506] A minimally ablation or angioplasty-incapable
barrel-assembly is self-contained to include an inmate power source
and is therefore capable of independent manual use for every
function but discharge, for which it is engaged in the airgun. It
is, however, more expensive than a minimally ablation or
angioplasty-capable barrel-assembly not intended for such versatile
use and not equipped with an inmate power source. Electrical
connection of the components within the barrel-assembly is
ordinarily by connection made by engagement of the barrel-assembly
in the airgun chamber. An embodiment of a minimally ablation or
angioplasty-capable barrel-assembly intended to be capable of
occasional manual use is connected to the airgun or another power
supply by means of a small power patching cable, and is less costly
than a fully capable barrel-assembly but is not usable as an
independent apparatus.
[2507] Since such a barrel-assembly might be equipped with a
battery, it will be seen that the transition from incapable to
capable comprehends a continuous spectrum of embodiments
comprehending every possible combination of features. Manually
side-sweeping or side-swabbing the lumen walls transluminally with
radial projection unit tool-inserts, the operator can stop and use
the turret-motor to remotely rotate the brushes in order to better
access the sides of the lumen not well covered because the
barrel-assembly does not rotate manually with ease. The
turret-motor can be used concurrently with manual use of the
barrel-assembly. For example, the oscillatory mode, explained below
in the section entitled Turret-motor Operational Modes, can be used
with or without a lubricant released by ejection tool-inserts to
assist in clearing tortuous stretches, and with side-sweeper type
tool-inserts deployed, for example, a scrubbing, abrading,
scraping, or shaving action.
[2508] The components within the barrel-assembly include tractive
electromagnets to recover miniballs, a turret-motor, and in even a
basic barrel-assembly intended for angioplasty, radial projection
unit or units with trap-filter. Combination forms that include
additional electrically operated components for transluminal use,
such as a laser catheter or atherectomy burr, are operated with the
barrel-assembly removed from the airgun during manual use. Such a
barrel-assembly constitutes a means for ablation, or angioplasty to
include atherectomy apart from its stenting function when inserted
in the airgun. During discharge, the turret-motor can be used to
rotate the muzzle-head, which can include one muzzle-port or
multiple muzzle-ports (but rarely more than four) located about its
circumference with radial symmetry or asymmetry.
[2509] As indicated, with an ablation or an ablation and
angioplasty-capable barrel-assembly, the rotatory mode of
turret-motor operation can be used both during an ablation or an
angioplasty with the barrel-assembly as an independent apparatus,
or during implantation discharge, during which time the
barrel-assembly is inserted into the airgun. Barrel-assemblies are
intended to be usable in different type ductus. Those for use in
blood vessels incorporate features to minimize procedural time,
obtruction, and prevent gas embolism. Grooves and passages are
provided to allow some blood to pass. Endoluminal time and
obstruction is also minimized with the aid of a semiautomatic
positioning system that allows miniballs to be placed more
precisely in a relatively dense formation than might be achieved
under manual control.
[2510] Nevertheless, the millimetric gauges of vessels can limit
the embodiment employed to one containing but a single barrel-tube.
Unlike a balloon, the muzzle-head of a barrel-assembly is not
collapsible. For vascular applications, a radial discharge
muzzle-head that includes from one to four barrels, usually two or
four, referred to as two-way or four-way, is connected to the end
of the barrel-catheter containing the barrel-tubes to form a
unitized whole, or barrel-assembly. As explained below, a
barrel-assembly to be used for placing implants at intervals too
fine for manual control is automatically controlled in position if
not the position-coordinated timing of the discharges.
[2511] Generally, a tight formation of miniballs is manually
initiated, or triggered, and automatically executed. Whether
intended for exclusively manual or for manual and automatic use, a
barrel-assembly usually incorporates a forward drive and sag
leveling and leveling and stabilizing device about the
barrel-catheter, as described below in the section entitled Forward
Drive and Sag Leveling and Stabilizing Device. One to three-way
barrel-assemblies with barrel exit ports at different angles are
used with vessels or other tubular structures that intimately
attached to their substrate, resist dissection round and about
without open surgery as would allow the vessel or duct to be
completely surrounded by a full rather than a partial stent-jacket,
whereas the four-way apparatus is used with structures readily
freed from the substrate, allowing a full stent-jacket to
completely surround or jacket the structure.
[2512] Generally, the obstruction posed by the barrel-assembly
during a procedure in a coronary artery should not take more time
than is required to achieve ischemic preconditioning (see, for
example, Corcoran, D., Young, R., Cialdella, P., McCartney, P.,
Bajrangee, A., and 13 others 2018. "The Effects of Remote Ischaemic
Preconditioning on Coronary Artery Function in Patients with Stable
Coronary Artery Disease," International Journal of Cardiology
252:24-30; Zhou, C. C., Yao, W. T., Ge, Y. Z., Xu, L. W., Wu, R.,
and 13 others 2017. "Remote Ischemic Conditioning for the
Prevention of Contrast-induced Acute Kidney Injury in Patients
Undergoing Intravascular Contrast Administration: A Meta-analysis
and Trial Sequential Analysis of 16 Randomized Controlled Trials,"
Oncotarget 8(45):79323-79336; Wang, S. Y., Cui, X. L., Xue, F. S.,
Duan, R., Li, R. P., and 3 others 2016. "Combined Morphine and Limb
Remote Ischemic Perconditioning Provides an Enhanced Protection
Against Myocardial Ischemia/Reperfusion Injury by Antiapoptosis,"
Journal of Surgical Research 202(1):13-25; Lu, X., Bi, Y. W., and
Chen, K. B. 2015. "Olmesartan Restores the Protective Effect of
Remote Ischemic Perconditioning Against Myocardial
Ischemia/Reperfusion Injury in Spontaneously Hypertensive Rats,"
Clinics (Sao Paulo, Brazil) 70(7):500-507; Heusch, G., Botker, H.
E., Przyklenk, K., Redington, A., and Yellon, D. 2015. "Remote
Ischemic Conditioning," Journal of the American College of
Cardiology 65(2):177-195; Zhu, S. B., Liu, Y., Zhu, Y., Yin, G. L.,
Wang, R. P., and 3 others 2013. "Remote Preconditioning,
Perconditioning, and Postconditioning: A Comparative Study of Their
Cardio-protective Properties in Rat Models," Clinics (Sao Paulo,
Brazil) 68(2):263-268; Laskey, W. K. 2005. "Brief Repetitive
Balloon Occlusions Enhance Reperfusion During Percutaneous Coronary
Intervention for Acute Myocardial Infarction: A Pilot Study,"
Catheterization and Cardiovascular Interventions 65(3):361-367;
Faircloth, M. E, Redwood, S. R., and Marber, M. S. 2004. "Ischaemic
Preconditioning and Myocardial Adaptation to Serial Intracoronary
Balloon Inflation: Cut from the Same Cloth?," Heart 90(4):358-360),
extendible to 21/2 to 3 minutes with the aid of medication (see,
for example, Matsubara, T., Minatoguchi, S., Matsuo, H., Hayakawa,
K., and 10 other authors, 2000. "Three Minute, But Not One Minute,
Ischemia and Nicorandil Have a Preconditioning Effect in Patients
with Coronary Artery Disease," Journal of the American College of
Cardiology 35(2):345-351; Heidland, U. E., Heintzen, M. P., Michel,
C. J., and Strauer, B. E. 2000. "Effect of Adjunctive Intracoronary
Adenosine on Myocardial Ischemia, Hemodynamic Function and Left
Ventricular Performance During Percutaneous Transluminal Coronary
Angioplasty: Clinical Access to Ischemic Preconditioning?,"
Coronary Artery Disease 11(5):421-428).
[2513] Any application of outward radial force on the surrounding
lumen, determined by the diameter of the muzzle-head, should not be
continued longer than is intended to:
[2514] 1. Reduce the risk of abrupt closure with or without
concomitant vasospasm (vasoreflex, angiospasm) (see, for example,
Arie, S., Checchi, H., Coelho, W. M., Bellotti, G., and Pileggi, F.
1990. "Coronary Angioplasty--Unstable Lesions and Prolonged Balloon
Inflation Time," Catheterization and Cardiovascular Diagnosis
19(2):77-83).
[2515] 2. Obtain more favorable morphological results (Zorger, N.,
Manke, C., Lenhart, M., Finkenzeller, T., Djavidani, B., Feuerbach,
S., and Link, J. 2002. "Peripheral Arterial Balloon Angioplasty:
Effect of Short Versus Long Balloon Inflation Times on the
Morphologic Results," Journal of Vascular and Interventional
Radiology 13(4):355-359), with reduced risk of restenosis (see, for
example, Glazier, J. J., Varricchione, T. R., Ryan, T. J., Ruocco,
N. A., Jacobs, A. K., and Faxon, D. P. 1989. "Factors Predicting
Recurrent Restenosis after Percutaneous Transluminal Coronary
Balloon Angioplasty," American Journal of Cardiology
63(13):902-905).
[2516] Using the noncollapsible muzzle-head, these occlusive
durations should not necessitate the use of an extracorporeal
perfusion system or chilling. If needed, however, newer
cariopulmonary bypass machines incorporate filters that
substantially eliminate the passage of microemboli to which
sequelary intellectual deficits (postperfusion syndrome,
postoperative cognitive dysfunction), renal insufficiency, and
pumonary dysfunction have been attributed (see, for example,
Landreneau, R. J., Mack, M. J., Magovern, J. A., Acuff, T. A.,
Benckart, D. H., Sakert, T. A., Fetterman, L. S., and Griffith, B.
P. 1996. "Keyhole" Coronary Artery Bypass Surgery," Annals of
Surgery 224(4).453-462, also cited above).
[2517] However, if due to disruption of the blood-brain barrier
secondary to the intervention, this would not remedy the condition
(see Ogami, R., Nakahara, T., and Hamasaki, O. 2008. "Probable
Blood-Brain Barrier Disruption after Carotid Artery Stenting--Case
Report," Neurologia Medico-chirurgica 48 (3):121-125; Wang, Y.,
Kilic, E., Kilic, U., Weber, B., Bassetti, C. L., Marti, H. H., and
Hermann, D. M. 2005. "VEGF Overexpression Induces Post-ischaemic
Neuroprotection, but Facilitates Haemodynamic Steal Phenomena,"
Brain 128(Part 1):52-63; Latour, L. L., Kang, D. W., Ezzeddine, M.
A., Chalela, J. A., and Warach, S: 2004. "Early Blood-brain Barrier
Disruption in Human Focal Brain Ischemia," Annals of Neurology
56(4):468-477; Warach, S. and Latour, L. L. 2004. "Evidence of
Reperfusion Injury, Exacerbated by Thrombolytic Therapy, in Human
Focal Brain Ischemia Using a Novel Imaging Marker of Early
Blood-brain Barrier Disruption," Stroke 35(11):2659-2661).
[2518] Intermittent withdrawal, reentry, and resumption increases
overall intracorporeal time thus defeating one object of invention.
A combined angioplasty and implantation procedure in a carotid
artery, for example, that requires the barrel-assembly to remain
within the lumen for more than a minute may benefit from
hypothermia. Continuing now the list of type barrel-assemblies thru
d. begun toward the beginning of this section, those usable
independently of an airgun draw power from an onboard power and
control housing. In large caliber ablation and angioplasty-capable,
that is, fully capable barrel-assemblies, which incorporate
numerous built in features that require more control electronics
and a high storage capacity power source, the housing if not well
shaped for ambidextrous handling is provided with a hand-grip.
[2519] In fully capable Barrel-assemblies which are smaller in
gauge, the housing itself can be configured as a pistol grip.
Simpler and less capable embodiments can be configured as a pistol
grip regardless of gauge. Regardless of conformation, the housing
provides a control panel on its upper surface for instant
viewability regardless of which hand is used. Continuing the
discussion above ending with item d.:
[2520] e. Ablation but not angioplasty-capable, which incorporate
within the muzzle-head and/or accommodate a bipartite radial
projection system but is usually larger in gauge than an
angioplasty-capable barrel-assembly and lacks the pressurized gas
diversion channels, heat-window or windows for thermoplasty, blood
passing channels, and embolic filter ischemia-preventive features
essential for use in the bloodstream, or
[2521] f. Ablation and angioplasty-capable, which include
pressurized gas diversion and blood passing channels, a heat-window
at the nose and often, an additional heat-window about the
turret-motor or along the sides to burn potentially embolizing
debris, and an embolic trap-filter (filter-trap, embolic filter),
in addition to a radial projection system. Angioplasty-capable
barrel-assemblies are made in the millimetric gauge range. Within
its size range, any barrel-assembly capable of performing an
angioplasty is capable of performing an ablation but costs more to
produce. An ablation and angioplasty-capable barrel-assembly
includes at least one barrel-tube (qv.) and at least one radial
projection system (qv.) in the muzzle-head as an aid to tracking.
In a bipartite or duplex barrel-assembly, supplementary radial
projection units are added to the barrel-assembly by sliding a
through-bore or combination-form radial projection catheter over
the barrel-catheter of the barrel-assembly before or after
advancement to the treatment site.
[2522] g Ablation but not angioplasty-capable combination-form
barrel-assembly, which is a through-bore radial discharge
barrel-assembly with an edge-discharge muzzle-head and patent
central channel through which a commercial cabled device such as a
laser or rotational cutting tool or other catheteric device can be
permanently or interchangeably inserted, that is, slid through the
bore using the barrel-assembly in the manner of a guide catheter,
midprocedurally with the barrel-assembly stationary in the lumen.
An ablation but not angioplasty-capable combination-form
barrel-assembly is usually equipped with a detachable snap-in
nose-hole plug with torsion spring-loaded nose-hole cover to shut
out debris during the exchange of cabled devices, lacks the
pressurized gas diversion channels and ischemia averting features
essential for use in the bloodstream, and is larger in gauge than a
barrel-assembly that is also capable of an angioplasty. Ablation
and ablation or ablation and angioplasty-capability is usually
conferred by the incorporation of a radial projection system that
is supplemented in a combination-form barrel-assembly with the
addition of a laser or atherectomy cutter. Such a barrel-assembly
is intrinsically ablation-capable, because its radial projection
system imparts ablation capability even with the laser or cutter
removed.
[2523] h. Ablation and angioplasty-capable combination-form, which
is a millimetric range gauge through bore barrel-assembly. Like an
ablation only combination-form barrel-assembly, an ablation or
ablation and angioplasty-capable combination-form barrel-assembly
has a patent central channel through which a commercial cabled
device such as a laser or rotational cutter or other catheteric
device can be permanently or interchangeably inserted. However, it
also provides gas pressure diversion paths and ischemia countering
features essential for use in the bloodstream, while omitting a
nose-hole cover, which would close the central channel for blood to
flow through when the channel is empty, and jut forward when open,
risking incisions.
[2524] Within its generally smaller diameter range,
combination-form barrel-assemblies capable of performing an
angioplasty are understood to be capable of performing an ablation.
Since ablation and angioplasty-capability is conferred by the
incorporation of a radial projection system, the barrel-assembly is
properly referred to as ablation or ablation and
angioplasty-capable even with the cabled device removed.
Combination-form barrel-assemblies are addressed in the section
below of like title.
[2525] One object of the invention is to be able to accomplish both
the removal of plaque or other obstructive matter and complete
implanting the intraductal component of the extraluminal type stent
described herein without the need to withdraw and reenter the
lumen. An edge-discharge muzzle-head designed to contain a
rotational burr or laser catheter at its center such as is
incorporated into a combination-form barrel-assembly is equally
capable of containing an endoluminal ultrasonographic probe or a
cryogenic angioplasty balloon, numerous ablation and atherectomy
devices on the market capable of being integrated into the
barrel-assembly. Integration thus has as an object prepositioning
to eliminate the need for withdrawal and reentry at times when
these devices may be needed.
[2526] With an ablation or an ablation and angioplasty-capable
barrel-assembly, a single vortex tube to provide cold or hot air,
or a gas cylinder to provide cold gas of the required temperature,
can be mounted at the rear of the barrel-assembly. To allow the
cold or hot air or gas to reach the inner (rear, proximal) surface
of the nose heat-window and circulate back into the central canal,
the nose heat-window is separated from the outer surface of the
ejection head and the gas delivery tube is smaller in diameter than
the central canal. A nose window that is piped (provided to its
rear with a barrel-tube diverted to serve as a supply line) may
appear equally versatile in function to a piped radial projection
unit; however, the value in an ability to project a fluid
substance, change the temperature, or both, axially is limited.
[2527] The ability to disconnect the barrel-assembly from the
interventional airgun and plug the vortex tube or gas cylinder into
its proximal end at any moment makes possible ablation or
angioplasty by the method preferred even mid-discharge, or
following the initiation of stenting implantation. As indicated,
when the central canal in an edge-discharge barrel-assembly is not
occupied by a cold air gun or gas cylinder delivery tube, the
distal end of the canal can be used to house a trap-filter silo by
channeling recursive gas through gas-return paths that are outside
(peripheral, radial) in relation to the barrel-tube or tubes.
[2528] The internal design of a barrel-assembly suitable for use in
the vascular tree incorporates gas pressure relief means such as
gas-return channels and a slit valve, so that the pressure of
discharge is contained within the barrel-assembly; discharge with
respect to the release of propulsive carbon dioxide gas or
compressed air with the barrel-assembly in the vasculature, even
when the airgun is not loaded, will not introduce gas into the
bloodstream. The generally torpedo-shaped distal component of the
barrel-assembly, or muzzle-head, supports the walls of a stenotic
vessel or duct and is usually jointed to flex and grooved or
furrowed to allow blood to pass over the surface. An ablation or
angioplsty-capable barrel-assembly with a disconnectable control
housing that has been disconnected is reduced to a minimally
ablation or ablation and angioplasty-capapble barrel-assembly.
[2529] That is, the feature that distinguishes a minimally from a
fully capable barrel-assembly is the presence of a control housing.
Because the central channel in a combination-form barrel-assembly
can serve as a guide catheter for the insertion of a number of
different cabled devices midprocedurally, it is preferred that any
device inserted be interchangeable rather than built in. Because it
must add some stiffness reducing trackability, a combination-form
radial projection catheter is usually slid over the barrel-catheter
of a barrel-assembly after the muzzle-head has been brought to the
treatment site or level.
[2530] While the central component is a device such as an endoscope
or thrombectomizer that cannot perform an ablation or an
angioplasty, the apparatus is an ablation or angioplasty-incapable
combination-form barrel-assembly. When the central component is a
laser or atherectomy cutting tool, the apparatus is ablation or an
ablation and angioplasty-capable combination-form barrel-assembly.
Adding a radial projection system or peripheral component makes the
combination-form barrel-assembly ablation or ablation and
angioplasty-capable even when the central component does not impart
this capability. For barrel-assemblies, pliancy for trackability is
a primary desideratum. To allow a narrow gauge with pliancy for
trackability, smaller ablation and ablation and angioplasty-capable
barrel-assemblies generally incorporate only electrically operated
radial projection units and only in the muzzle-head.
[2531] These radial projection units can be used to discharge a
lubricant from ejection tool-inserts, adding slipperiness to
narrowness, and the oscillatory mode of the turret-motor, can be
used to assist in tracking. As addressed below in the section of
like title, a combination-form radial projection catheter, or
radial projection catheter with a central channel, can be slid over
the extracorporeal or luminally prepositioned barrel-catheter as a
kind of guide wire. The leading edge of the radial projection
catheter is slip up to the rear of the muzzle-head. The coaxial
pair can then have a reduced pliancy and increased gauge that would
have prohibited luminal placement while at the same time extending
radial projection units along the entire intracorporeal length. A
combination-form radial projection catheter can be added to a
barrel-assembly by being slid over the barrel-assembly
barrel-catheter.
[2532] So that the front of a combination-form radial projection
catheter can be slid forward over the barrel-catheter, an ablation
or an ablation and angioplasty-capable barrel-assembly must provide
a disconnectable power and control housing, or hand-grip configured
battery-pack with the control panel mounted to the outside. Since
most uses for a radial projection catheter do not relate to
ballistic implantation, the catheter is made as an independent
apparatus with its own power and control housing. When combined
with the projection catheter slid fully forward so that its front
edge abuts against the rear of the muzzle-head, the rear of the
radial projection catheter power and control housing is slid back
onto the barrel-catheter and flush against the rear of the
projection catheter housing, the two in juxtaposed (adjacent,
ganged) relation.
[2533] A small lock lever with cam detent at the bottom of each
housing allows the housings to be slid along the barrel-catheter to
any position and locked in place, much as the tail stop in a
sliding pipe, pony, or bar clamp. Fixing the projection catheter
housing in position prevents unintended sliding of the projection
catheter along the barrel-catheter by contact with the lumen wall.
Each apparatus made to be fully capable when independent of the
other, the functions of each remains separate when the two are
joined. Thus, electrically or fluidically connecting one into the
other in order to eliminate one battery, for example, is not done.
The combination is obtained with apparatuses of either type matched
in gauge.
[2534] The power and control housing of the ablation or the
ablation and angioplasty-capable barrel-assembly is disconnected,
and the front end of the radial projection catheter is slid over
the barrel-catheter of the barrel-assembly up into contact with the
back of the muzzle-head. The interfaces, that is, front end of the
radial projection catheter and rear of the muzzle-head complement
in engaging relation that includes any electrical or fluid
connectors. For trackability, the barrel-assembly is usually
introduced without the radial projection catheter. If the lumen is
too occluded for this, then a radial projection catheter of smaller
gauge can be first be used independently to clear the way just
enough so that the barrel-assembly can pass. Once in, the
barrel-assembly is overlain by the radial projection catheter for
its ablation or angioplasty functions.
[2535] If to be used during ballistic implantation, the radial
projection catheter remains in place; otherwise it is withdrawn and
the barrel-assembly used for placing the miniballs. To reduce the
risk of injury when the radial projection catheter is introduced
the outer edges at its leading end are rounded and any electrical
or fluid connectors to the rear of the muzzle-head are placed
medially (alongside the longitudinal axis). The combination of two
such components is equivalent to an ablation or an ablation and
angioplasty-capable barrel-assembly with integral radial projection
catheter over its intracorporeal length, which is less versatile
but less expensive. The combination can be thought of as an
ablation or an ablation and angioplasty-capable barrel-assembly in
two separable parts where for better trackability, the
barrel-assembly can be introduced into the lumen first, then the
radial projection catheter slid (advanced, tracked) over the
barrel-catheter.
[2536] Bipartite barrel-assemblies are addressed below in the
section entitled Distinction in Ablation or Angioplasty-capable
Barrel-assemblies as Unitary or Bipartite. Barrel-assemblies are,
however, substantially increased in capability when the
barrel-catheter is encased within a surrounding jacket or sleeve
that contains radially outward directed or side-looking tools such
as injectors that allow the targeted release of medication into
lesions, if necessary, at a preferred temperature, and cutting
heads that can ablate or angioplasty. This capability is attained
by introducing the barrel-assembly, situating the muzzle-head as
necessary, and then using the barrel-catheter as a kind of guide
wire to slide a combination-form radial projection catheter, as
addressed below in the section of like title, until the distal or
forward end of the latter abuts upon the proximal or rear end of
the muzzle-head.
[2537] Electrical radial projection units in the muzzle-head can
similarly use system-neutral syringe tool-inserts to reduce
endothelial cling by ejecting a lubricant during transluminal and
rotatory movement of the muzzle-head itself as well as to prepare
the lumen for the covering of the barrel-catheter with a
combination-form radial projection catheter. Electrical projection
units in the muzzle-head are wired within the barrel-assembly. This
allows their use independently of a radial projection catheter and
avoids the need to torque (rotate) the barrel-assembly or to use
the turret-motor to align electrical contacts at the leading edge
of the projection catheter and rear of the muzzle-head in order to
make the connection.
[2538] Fluid ejection tool-inserts or ejectors are not so limited
being capable of emitting a fluid indefinitely; however, due to the
greater space requirement that a fluid circuit imposes, these can
only be incorporated into larger muzzle-heads. The terms ablation
and ablation and angioplasty-capable are reserved for
Barrel-assemblies which whether unitary or bipartite, include
radial projection units. These units always accept interchangeable
tool-inserts, and therefore always confer ablation or ablation and
angioplasty-capability. Depending upon the device introduced into
the central channel as the central component of a combination-form
barrel-assembly, an ablation but not an ablation and
angioplasty-capable barrel-assembly when the latter is used in the
bloodstream can have fastened at the front a tortion spring-loaded
nose-cover.
[2539] The different types of combination-form barrel-assemblies
and use of hole-covers are addressed below in the section entitled
Types of Combination form Barrel-assemblies. Characterization as to
type is independent of the number of barrel-tubes. For optimal
manipulatiblity, airgun separable barrel-assemblies are preferably
free-standing, or without connection to an external device such as
by an electrical cord leading to a power source whether that within
the airgun enclosure or housing. The combination-forms, however,
when enclosing the cable of a laser, endoscope, and/or an
atherectomizing device are tethered to the support electronics
usually contained in a separate console.
[2540] VII1b. Capabilities of Different Type Barrel-Assemblies
[2541] A simple pipe consists exclusively of a ballistic component
used to implant or recover miniballs. A simple pipe is a monobarrel
without surrounding shell at the muzzle-head; shelled or jacketed
at the muzzle-head, it would become a radial discharge monobarrel.
Within the limits set by not constricting the bore, the muzzle-head
of a simple pipe is also bendable prior to introduction, allowing
adjustment for small apertures and awkward angles of approach to
abut flush to the surface at the treatment site. Provision of a
muzzle-head that is bendable after introduction is not addressed
herein. Minimizing the entry cross sectional area, a simple pipe is
intended for use where a flat-sided radially asymmetrical radial
monobarrel of fixed cross sectional area would cause stretching
injury to the laryngeal entry, for example, and a shell would
interfere or prevent a clear view of the detailed anatomy at the
aiming point.
[2542] Simple pipe barrel-assemblies will seldom be large enough in
diameter to allow a service-catheter or miniature cabled device
such as a laser or scope to be passed through the exit-hole or
muzzle-port. However, to treat the lumen wall before or after
discharge midprocedurally without the need to withdraw, larger
simple pipes can be used thus. When not provided with a side-port,
the barrel-assembly must be removed from the airgun to access its
entry or proximal opening. Characterization of simple pipes as
ablation and angioplasty-incapable is thus based upon a lack of
intrinsic means therefor in the form of the radial projection units
in capable barrel-assemblies.
[2543] Not only must the excimer laser or irreversible
electroporation electrodes for ablating tissue addressed below in
the section entitled Service Catheters pass through the muzzle-port
but the operator must be provided with a clear view of the
treatment area. This may necessitate the additional clearance to
pass a subminiature fiberoptic endoscope. The same applies to all
but the largest ablation or angioplasty-incapable radial discharge
barrel-assemblies. The miniballs can consist of any kind of
medication that can be prepared in the form of a tiny ball, and
generally include adjuvant or implantation-supportive substances,
to include a tumefacient, antibiotic, adhesive, tissue hardener, or
surgical cement, for example.
[2544] Inserting such an isolated ballistic component
barrel-assembly within the bore or central channel of a
combination-form radial projection catheter effectively converts it
into an ablation or an ablation and angioplasty-capable
barrel-assembly despite the lack of radial projection units about
the muzzle-head. Miniball constituents are organized for release in
the sequence preferred. Miniballs not for use with a stent-jacket
that despite high contrast might prove difficult to recover if
misplaced or dropped, are provided with sufficient magnetically
susceptible, usually ferrous material, if nonabsorbable, then
encapsulated iron powder, if not, then superparamagnetic magnetite
or maghemite nanoparticles or finely grained powder, to allow
recovery with the electromagnets always present at the discharge
end of every barrel-assembly.
[2545] Miniballs for stenting can consist entirely of magnetic
stainless steel, usually encapsulated within layers of suppportive
medication or other therapeutic substances. A barrel-assembly with
a peripheral component, or radial projection system, can use
injection, ejection, inert bit cutting head, and temperature
altering tool-inserts to prepare the treatment site for and/or
provide followup treatment to ballistic implantation with single
luminal entry. Preparation generally consists of removing diseased
or obstructive tissue. It is the peripheral component that imparts
ablation or angioplasty capability. Both preparation and followup
can include the injection at a preferred temperature of a
tumefacient, antibiotic, surgical cement, or tissue hardener, for
example, into the lumen wall.
[2546] When ballistic implantation is not contemplated, an ablation
or an ablation and angioplasty-capable barrel-assembly,
combination-form barrel-assembly, separate radial projection
catheter, or combination-form radial projection catheter can be
used to clear and introduce any kind of injectable medication
and/or other substance into the wall of a diseased or obstructed
ductus. Barrel-assemblies and miniball implants have applications
unrelated to stenting. A barrel-assembly without a peripheral
component (radial projection system), can be used to implant
medication ballistically, and barrel-assemblies with a peripheral
component can be used to effect interventional measures such as the
removal of diseased or obstructive tissue by cutting, thermoplasty,
or cryoplasty, and the targeted introduction into lesions along the
lumen wall of any fluid substance by injection as well as
ballistically in any combination.
[2547] Either a simple pipe with an endoscope permanently fastened
or lashed alongside or a radial discharge barrel-assembly with an
attached or built in angioscope or fiberoptic endoscope is used to
implant medication and/or radioactive seed miniballs in the wall
surrounding the tracheobronchial airway, gastrointestinal tract, or
a body cavity, for example. Much stenting of the airway will be
veterinary or pediatric using a simple pipe with a padded distal
end to prevent gouging. Radial discharge barrel-assemblies are
intended for use primarily in ductus and vessels that tend to lack
anatomical landmarks where the lumen transmits blood or other
contents and the size of the vessel or duct is such that
maneuverability and accurate positioning are difficult or
impossible. Less well defined and extensive lesions will similarly
present little structural differentiation. Stay insertion tools are
readily applicable to structured and unstructured lumina.
[2548] To assure recoverability if dropped or mispositioned,
medication miniballs and stays, which must fully disintegrate,
incorporate superparamagnetic magnetite or magnemite. Minimally or
marginally ablation or ablation and angioplasty-capable
barrel-assemblies are intended to apply ablative or angioplastic
action as adjunctive to implantation discharge, whether preceding,
during, or succeeding discharge, and are airgun-dependent. More
specifically, minimally capable barrel-assemblies are for
noncomplex lesions where any vulnerable or unstable plaque would be
destroyed by being swept over by a cautery prior to discharge. Such
barrel-assemblies may substitute a nonmotor heating coil with
wraparound heat-window for a turret-motor with heatable windings as
a secondary function, and omit radial projection units.
[2549] These therefore lack an inmate source of power or an onboard
control panel and are seldom equipped with all of the tissue
reduction features of ablation or ablation and angioplasty-capable
barrel-assemblies, whence the designation `minimal.` Because a
pistol allows greater manipulability, minimally capable
barrel-assemblies for use with pistols warrant more of these
features and may match capable embodiments in ablative ability.
However, a pistol does not permit the control over exit velocity or
precise placement as does a stage mounted interventional airgun.
Thus, although not configured for separate manual use, minimally
capable barrel-assemblies are not necessarily less well equipped or
capable in the more limited ability to deliver heat or ablative
action per se.
[2550] When not requiring to be distinguished as to usability in
the bloodstream, minimally capable barrel-assemblies, as airgun
dependent for powering the internal components and thus requiring
electrical reconnection whenever removed from the airgun, are
referred to collectively as minimally or marginally ablation or
ablation and angioplasty-capable barrel-assemblies. Ablation and
ablation and angioplasty-capable barrel-assemblies include the
capabilities of minimally capable barrel-assemblies but are usable
independently of an airgun. Unless duplicate controls are mounted
on the airgun enclosure (for use by an assistant), the control
panel is not placed there but rather immediately and ambidextrously
on top of the grip-configured power and control housing.
[2551] The advantage in the ability to use the barrel-assembly
independently of an airgun is the freedom of manipulation essential
to accomplish the preparatory therapeutic measures for implantation
and then, inserting the proximal end in the airgun, inititate
implantation discharge without the need to move or withdraw. When
discharge implantation is not contemplated, the barrel-assembly can
be used as a separate apparatus or a radial projection catheter
used instead. Distinguished as to usability in the bloodstream,
both ablation and ablation and angioplasty-capable
barrel-assemblies are equipped, internally powered, and usable
apart from an airgun, the angioplasty-capable type comprehends the
function of the equivalent ablation only barrel-assembly, but is
limited to the range in size suitable for use in the
bloodstream.
[2552] Since Barrel-assemblies which are capable of angioplasty as
well as ablation encompass the function and can accomplish the work
of the comparable ablation only or angioplasty-incapable type, and
the difference between these consist of gas pressure diversion
means, the figures depict the angioplasty-capable type. Simple pipe
barrel-assemblies lack a torpedo-shaped body shell or jacket about
the muzzle-head when this is unnecessary for preventing
perforations expedite direct aiming in relation to the structured
or differentiated anatomy inside the trachea, for example. Since
this jacket is also needed to mount ablation or angioplasty
components, a simple pipe is limited to the placement and recovery
of miniballs. When disengaged from the airgun, a simple pipe can be
used for aspiration, irrigation, or to deliver a therapeutic
solution, for example.
[2553] Ablation or angioplasty-incapable barrel-assemblies serve as
extensions to the airgun barrel that are configured to allow the
delivery of implants into the wall of a lumen, or exceptionally,
into the body wall (paries) or an internal organ. These include
simple pipes and radial discharge Barrel-assemblies which lack the
essential to features perform an ablation or an angioplasty, to
include radial projection units, heat-windows, a trap-filter, all
described in sections of like title to follow. Functionality
inseparable from cost, this type can be made at least cost. Since
adding features tends to increase diameter, certain circumstances
may call for relinquishing nonessential features to allow greater
clearance.
[2554] While no simple pipe, which is a barrel-assembly without a
protective outer shell or jacket surrounding the muzzle-head, and
not all radial discharge barrel-assemblies are ablation much less
angioplasty-capable, all ablation or ablation and
angioplasty-capable barrel-assemblies are of the radial discharge
type. Minimally ablation or ablation and angioplasty-capable
barrel-assemblies are meant to allow ablation or angioplasty
intermittently or continuously during discharge. Seldom critical,
the transit time for discharge can usually be set to match the
optimal exposure time of the lumen wall to heat or other tissue
removal shaving or abrasive action used.
[2555] Because the recovery electromagnets toward the nose of the
muzzle-head should remain available for recovering any dropped
miniballs during discharge, the conjoined processes are usually
performed during retraction or withdrawal rather than advancement
with an annular turret-motor winding heat-window supplying the
heat. While not meant to be used apart from the airgun and not
requiring a more elaborate side-socket for connecting different
electrical and fluid lines, a minimally ablation or ablation and
angioplasty-capable barrel-assembly still requires access down the
central channel or a barrel-tube for the limited purpose of
admitting a temperature-changing catheter or cold air gun line for
quickly dropping the temperature down from that used to ablate or
thermally angioplasty or elevate the temperature when terminating
cryoablation or cryoplasty.
[2556] This is best accomplished without modification to the
barrel-assembly by removal from the airgun and passing the
temperature-changing catheter through the end-plate. Exceptionally,
a simple side-socket with dedicated barrel-tube, preferably one
diverted to serve as a radial projection unit pipe, can be
incorporated. While ballistic discharge requires connection to an
airgun, ablation and ablation and angioplasty-capable
barrel-assemblies can be made fully self-sufficient for performing
an ablation and/or angioplasty. The embedded microcontrollers and
other components required follow from the features embodied. These
can include a turret-motor and recovery electromagnets that can be
switched from functioning as actuators to functioning as heating
elements, electrical and/or fluidic radial projection systems, and
a viscous or daspot damped solenoid deployed and retracted
run-ahead embolic filter.
[2557] In a combination-form barrel-assembly, an electrical and/or
fluidic side-socket allows the control console of the cabled device
inserted to be operated by an assistant. A side-socket can also
allow connection to a number of external canisters (cylinders,
tanks) containing various medical and flush fluids that an internal
reservoir not configured to accept refill containers for fluid
delivery or cisterns for collection during aspiration cannot
accommodate. When discharge requires the turret-motor to rotate the
muzzle-head making the turret-motor unavailable as a heating
element, hot-plate radial projection unit tool-inserts are used for
this purpose. To minimize confusion and the risk of human error,
controls are kept with the device controlled. With a minimally
ablation or ablation and angioplasty-capable barrel-assembly, the
controls for these, just as for radial projection units when
shaving or abrading tool-inserts are used, are mounted to the
airgun.
[2558] In barrel-assemblies which afford sufficient diameter, the
nose can contain a heat window that encircles a cabled device, such
as a fiberoptic endoscope or an embolic filter silo with deployment
solenoid. Such a heat-window is a hemitoroidal dome with the convex
surface directed forward (downstream, distad). In an embodiment
that includes abrading or cutting (shaving) tool-inserts, either a
laser or an embolic filter will serve to eradicate any debris that
might risk embolization. An embolic filter can be simultaneously
deployed when an atherectomizing tool is energized. To be certain
that the filter is deployed before debris is generated, the tool
receives current only after a brief delay. To avert the release
into the lumen of debris from vulnerable or unstable plaque, the
filter can also be deployed independently following introduction of
the catheter.
[2559] When the tool is turned off and thus retracted (stowed), the
filter is retracted into the silo following a brief delay. Also
independently deployable and retractable, concern that debris may
be liberated upon withdrawal is responded to by overriding
automatic retraction. Should a minimally capable barrel-assembly be
ensheathed within a comibnation-form radial projection catheter as
a bipartite ablation or ablation and angioplasty-capable
barrel-assembly, as addressed below in the section entitled
Through-bore, or Combination-form, Radial Projection Catheters,
then the controls are located at the top of the projection catheter
power and control housing. The object in combining discharge and
thermal angioplasty capabilities, for example, is to destroy
vulnerable plaque and potentially embolizing debris before stenting
as a routine precaution but more immediately, to preclude the
fractures of fibrous caps by contact with the apparatus.
[2560] Hyperplastic sequelae are avoided by medicating and/or
irradiating the miniballs, which inherently targeted, considerably
reduces if not eliminates the need for systemic medication. While
such a barrel-assembly incorporates means for ablation or
angioplasty, it is not meant for use apart from the airgun.
Accordingly, power for its internal components--turret-motor,
recovery electromagnets, radial projection units, and trap-filter -
is drawn from the airgun power supply, and the signals for
controlling these components are set on the airgun control panel.
The connections for both are made through the end-plate at the
proximal end of the barrel-assembly when engaged in the airgun
chamber.
[2561] In Barrel-assemblies which lack a side-socket, the end-plate
must serve as an end-socket, as addressed below in the section
entitled Ablation or Ablation and Angioplasty-capable
Barrel-assembly End-socket, for the attachment of external devices,
necessitating disengagement from the airgun and thus disabling
discharge. By contrast, barrel-assemblies with a side-socket, as
addressed below in the section entitled Ablation or Ablation and
Angioplasty-capable Barrel-assembly Side-socket, can continue to
discharge medication miniballs, for example, at any time during the
primarily initial ablation or angioplasty procedure. Reciprocally,
an end-socket disallows the application of chilled gas during
discharge. To provide such a barrel-assembly with a side-socket
that would maintain power while the barrel-assembly was removed
from the airgun would impart greater functionality.
[2562] However, that would make it an ablation or ablation and
angioplasty-capable type, as addressed below, but one inadept in
remaining tethered and lacking the onboard power and control panel
that yield the self-containment and gain in range and ease of use,
or functionality, that make an ablation or ablation and
angioplasty-capable barrel-assembly worth the additional expense.
By contrast, a proper ablation or ablation and angioplasty-capable
barrel-assembly need be tethered only when a combination-form, as
addressed below, with commercial laser or a specially adapted
rotational atherectormy burr, for example, installed. Since
engagement in the airgun interferes with free manual use or
manipulation, the discretionary use of such a barrel-assembly for
use while connected to and drawing power from the airgun power
supply before initiating medication and/or stenting miniball
discharge is accomplished with the aid of the rate of advancement
or retraction-setting linear positioning stage to which the airgun
is mounted.
[2563] Separate use of the barrel-assembly before or removing it
from the airgun during implantation discharge to allow free
manipulation necessitates reconnection to a power source, usually
reconnection to the airgun power supply through an external socket
on the airgun enclosure. Ablation or ablation and
angioplasty-capable barrel-assemblies are meant to be capable of
performing an ablation or an angioplasty independently of an
airgun. In so doing, the barrel-assembly supplants alternative
methods of treatment, such as balloon angioplasty. Having completed
this action, such a barrel-assembly can be inserted into an airgun
to initiate stenting implantation discharge without the need for
withdrawal from and reentry into the body.
[2564] Self-contained and able to attach additional components by
means of a side-socket, ablation and ablation and
angioplasty-capable barrel-assemblies can be freely inserted into
or removed from an airgun whenever necessary and therefore allow
discharge which can be intermittently interrupted for ablative or
angioplastic use without the need to withdraw and reenter.
Discharge can be to deliver medication miniballs preparatory to the
ablation or angioplasty or pursuant to that just completed, or to
emplace the intraductal component of an extraluminal stent.
Different or multicoated miniballs can be used to accomplish
medication, stenting, or both, and the operator can freely switch
between angioplasty and discharge as desired.
[2565] While not preferred as losing the advantage in the ability
to immediately shift between ablation or angioplasty and stenting
without the need to withdraw, such a barrel-assembly can also be
used to perform an angioplasty preparatory to conventional
(endoluminal) stenting or to stent following conventional (balloon)
angioplasty. Barrel-assemblies for use in the circulatory system
must incorporate pressurized gas diversion and pressure dissipation
channels, plural means for preventing a dropped miniball from being
carried off by the bloodstream, and blood-grooves, blood-tunnels,
and radial projection units as means for minimizing obstruction to
the flow of blood. These components are described in sections of
like title below. Angioplasty-capable barrel-assemblies thus
usually exceed the complement of features required in
Barrel-assemblies which are capable of ablation but not
angioplasty.
[2566] Since these are made for use in the vascular tree, a narrow
diameter is essential at the same time that gas return channels and
usually blood-grooves must be provided. Combination-form
barrel-assemblies are addressed below in the section entitled
Through-bore, or Combination-form, Barrel-assemblies:
Barrel-assemblies which Accommodate or Incorporate Means for
Ablation, Thrombectomy, Atherectomy, Atherotomy, and/or Endoscopy.
Luminal diameter the limiting factor, combination-form
barrel-assemblies for use in the vascular tree will usually be
restricted to no more than two barrel-tubes. When the nose-hole of
a combination-form barrel-assembly or a combination-form radial
projection catheter is left uncapped when introduced into an
artery, the central channel must first be allowed to fill with
blood. This is accomplished by pausing with the proximal side-port
or ports extracorporeal to vent air from the central channel.
[2567] Wetted with heparin solution, the central channel can then
be a. Left unoccupied for blood to flow through, b. Used as a
guideway for numerous different therapeutic and/or viewing
interventional devices which can be changed midprocedurally without
the need to withdraw the barrel-assembly, or c. Used to permanently
enclose such a device or a form thereof adapted for the purpose. If
occupied but leaving sufficient cross sectional clearance, the
central channel may still allow some blood to pass. If the
muzzle-head or radial projection catheter is smaller in outer
diameter than the ductus, blood will flow past along its periphery.
If fine enough in diameter, more than one device, such as one for
viewing and another for performing work, can be accommodated.
[2568] If not inserted prior to entry, a singular catheteric or
cabled device that matches the central channel in diameter is
inserted gradually to minimize pumping pressure on the blood within
the central channel, and when withdrawn with the combination-form
remaining stationary within the lumen, then gradually to minimize
the vacuum created. Commercial lasers and devices for intraductal
ultrasound and endoscopy, for example, require connection to a
remote control console, and thrombectomizing and atherectomizing
devices are powered and controlled from a hand piece. Such devices
are inserted distal end first into the combination-form through a
larger proximal side-port that remains well extracorporeal and does
not interfere with intermittent reinsertion of a barrel-assembly in
the airgun if necessary for discharge or to take advantage of the
precise transluminal positioning capability imparted by the airgun
linear positioning stage.
[2569] For use in a ductus containing debris, such as in the
gastrointestinal tract, especially when it is desired to exchange
viewing devices, the central channel in a combination-form
barrel-assembly or radial projection catheter should be prevented
from obstruction. To this end, the nose-hole has inset a plug
consisting of a surround extending rubbery or resilient fingers
toward the center where the free ends meet. When retracted, the
fingers wipe down the sides and front end of the protruded portion
of the cabled device and close behind it to block the entry of
debris. A snap-in spring-loaded nose-cap is not preferred as
opening to one side and thus necessitating addtional protrusion to
attain an unobstructed field. Such self-closing mechanisms are
unsuited to use in the bloodstream where it would obstruct the flow
of blood or in the airway where it would obstruct the flow of air
whenever the central channel was left empty, which in most
instances is for this express purpose.
[2570] Ablation or ablation and angioplasty-capable
barrel-assemblies are radial discharge barrel-assemblies with
radial projection units and a turret-motor with windings that can
be heated to perform a thermal angioplasty. Combination-form
barrel-assemblies additionally incorporate a laser, endoscope,
intraductal ultrasound, or other usually static component within
the central canal or allow passage therethrough of a rotatory
cutting tool. To enlarge the central canal, the barrel-tubes must
be situated radially outwards, which configuration is referred to
as edge-discharge. A configuration whereby the barrel-tubes are
closer toward the central axis is referred to as
center-discharge.
[2571] Ablation or ablation and angioplasty-capable
barrel-assemblies generally confine radial projection units to the
muzzle-head where these can be used, for example, to release a
lubricant during transluminal movement rather than include a radial
projection jacket that extends over the intracorporeal length that
would adversely affect flexibility, hence, trackability. When an
ablation or ablation and angioplasty-capable barrel-assembly with
permanent radial projection jacket extending over its
intracorporeal length lacks sufficient flexibility to track a
curved or tortuous stretch, a radial discharge barrel-assembly
without radial projection units other than in the muzzle-head is
positioned in the lumen first and a combination-form radial
projection catheter slid over the barrel-catheter in the manner of
a guide wire.
[2572] Combination-form radial projection catheters are addressed
below in the section below of like title. Ablation or ablation and
angioplasty-capable barrel-assemblies comprised of a size-matched
barrel-assembly and a combination-form radial projection catheters
are addressed below in the section entitled Distinction in Ablation
or Ablation and Angioplasty-capable Barrel-assemblies as Unitary or
Bipartite. Neither type cable prevents flexion of a convoluted
segment joining proximal and distal portions of a flexible
muzzle-head. Thermoplasty-capable barrel-assemblies require a
muzzle-head body (outer shell, jacket) with heat conductive and
insulative properties to permit the heat generated within the body
to be transient conducted toward the lesions, most often
atheromatous, which are usually delimited longitudinally and
radially asymmetrical, in a directed manner as described below.
[2573] Polytetrafluoroethylene-coated nonferromagnetic stainless
steel affords the surface slippage to avert endothelial clinging.
Whenever the turret-motor is joined to the more distal elements of
the muzzle-head (ejection head, recovery electromagnet assembly) by
a segment or joint of flexible convoluted tubing, the muzzle-head
body shell must be divided between the portions of the muzzle-head
distal and proximal to the flexible joint. While heat-windows,
slits, or slots for thermal angioplasty (addressed below) heated by
sending heating current to both the turret-motor and the
electromagnet assembly in a center-discharge muzzle-head must be
divided between the shells proximal and distal to the flexible
joint, the path through the barrel-assembly for passing a capillary
or filiform catheter for rapid cooling of the heated elements to
body temperature through a spare barrel-tube (service-channel) or
the central canal of the peribarrel space and up through the
capillary catheter channel in the ejection head in only this type
of barrel-assembly is continuous.
[2574] In a combination-form barrel-assembly, the central canal may
be occupied by the cable of a therapeutic device, such as a laser,
and/or viewing device such as an endoscope or intraductal
ultrasound probe, making it unavailable for insertion of a cooling
catheter. With this type of barrel-assembly, which requires an
edge-discharge muzzle-head such as shown in FIG. 66, the cooling
catheter must be passed down to the muzzle-head through an
available barrel-tube. Because the internal diameter (caliber,
gauge) of the barrel-tube can be on the order of 0.4 millimeters,
the cooling catheter must be thin. To allow the cooling catheter to
be fed down to the muzzle-head thus requires that it be made of a
relatively rigid polymer, usually polytetrafluoroethylene.
[2575] In barrel-assemblies designed to use the turret-motor or
tractive electromagnets as heating elements for thermal
angioplasty, these same materials afford the effectively
nonmagnetic properties and low thermal conductivities or heat
transfer coefficients, so that by placing a pane of sheet silver or
copper, which are high in thermal conductivity, in the muzzle-head
body, allows heat regulated in temperature by controlling the
current to the windings, to be directed, in effect beamed, from the
body toward the lumen wall over a defined area. Unlike simple pipe
barrel-assemblies, which are intended for use primarily in the
airway, radial discharge barrel-assemblies are intended to be
usable in the vascular system as well as small and structurally
undifferentiated ducts. The latter factor and need for operative
speed account for embodiments that are able to deliver multiple
implants with each discharge.
[2576] As opposed to use in a body cavity, the use of a simple pipe
barrel-assembly in a ductus or vas in a human is essentially
limited to the airway. Ablation or angioplasty-incapable (plain
discharge, limited purpose) radial discharge barrel-assemblies as
shown in FIGS. 34, 35, and 43 are limited to use with an airgun for
implantation and might be used independently of an airgun only as
an aspiration line. By contrast, ablation or ablation and
angioplasty-capable barrel-assemblies (angioplasty
barrel-assemblies, thermal angioplasty barrel-assemblies), such as
those shown in FIGS. 44, 48, 49, 50, might be used solely to
perform an angioplasty even when not planned to be followed by
stenting, or might first be used independently of an airgun for
angioplasty, and thereafter, without withdrawal from the patient,
inserted at the free or proximal end into the barrel of an airgun
to initiate stent implantation.
[2577] Unless it incorporates a rotatory atherectomy burr or laser
catheter, an angioplasty barrel-catheter powered by a hand-grip
shaped lithium-polymer or silver-zinc battery pack need not be
tethered, or connected by hard wiring to a power supply whether
inmate in the airgun or another. With either a rotational cutting
burr or laser incorporated, local controls are included in the
onboard barrel-assembly control panel, but the burr pneumatic drive
and laser photoactivation components within the consoles of these
cannot be miniaturized for incorporation into a barrel-assembly,
which accordingly requires a pneumatic or fiberoptic cable
connection. However, stenting always follows angioplasty, and the
connection to either such drive, which is located at the proximal
end of the angioplasty barrel-assembly, is designed to allow
immediate disconnection from the console and reconnection to the
airgun by means of the same connector fitting.
[2578] The barrel-assembly should be devised and chosen to avoid
unnecessary length. Bends are eliminated from the initial period of
discharge by providing the airgun with a barrel of some length,
into which the proximal length of the barrel-assembly is inserted.
In an angioplasty barrel-assembly, this would result in the length
of the barrel-assembly to be inserted into the barrel of the airgun
extending proximally past the hand-grip shaped battery pack with
control panel mounted, thus denying use of this length when or
while the barrel-assembly was used independently of the airgun for
angioplasty. Rather than to allow the proximal segment of the
barrel-assembly, or barrel insertion segment, to be denied for
intraductal insertion, the hand-grip is slid backward or toward the
proximal end of the barrel-assembly when the barrel-assembly is
used independently of the airgun for angioplasty.
[2579] Angioplasty preceding stenting, the hand-grip is initially
in the proximal position where it is in electrical contact with the
terminals to each side-sweeping brush or other radial projection
unit tool-insert lift raising thermal expansion wire as addressed
below in the sections below entitled Radial Projection Units,
Structure of Electrically Operated Radial Projection Units, and
Radial Projection Unit Control and Control Panels, Elecrical and
Fluidic or Piped, and the turret-motor and recovery electromagnets
while used as heating elements for thermal angioplasty. When the
barrel-assmbly is to be inserted into the barrel of the airgun, the
grip with forward drive and sag leveling and stabilizing device if
present is slid forward or distally up to a detent or stop marking
off the length of the airgun barrel and disconnecting the onboard
battery pack from electrical contact with these terminals, which
then can make contact with the terminals within the chamber of the
airgun or attached to the hand-grip.
[2580] In use for implantation, the barrel-assembly is generally a
passive component of the interventional airgun. When an ablation or
an ablation and angioplasty-capable barrel-assembly is not needed
for discharge implantation, the proximal end-plate need not be
inserted into an airgun. An end-socket therefore allows connection
to an external apparatus such as an aspiration pump, refrigerant
line, or endoscope as necessary. If the barrel-assembly is of the
combination-form type with a central channel, then commercial
cabled devices can be incorporated also. When the barrel-assembly
must remain engaged in the airgun, a side-socket is necessary. An
ablation or ablation and angioplasty-capable barrel-assembly, which
except for implant discharge can be used independently of an
airgun, is powered by an on-board battery pack in the power and
control housing and not tethered by an electrical cord.
[2581] It should seldom if ever be necessary to take power and
electrical control signals through an electrical cable regardless
of the number and type of components used. Current battery
technology and an onboard servodrive or amplifier controller to
execute programmed oscillation of the turret-motor as addressed
below in the sections entitled Turret-motor Operational Modes on a
sustained basis allow the barrel-assembly to remain portable and
untethered. An ablation or ablation and angioplasty-capable
barrel-assembly for use in an airgun but detachable therefrom as
desired can take power from an onboard battery pack, a cable or
cables, or from the airgun power supply through an extension cord
and side-socket, as addressed below in the sections entitled
Engagement of the Barrel-assembly in the Airgun and Barrel-assembly
Side-socket and must relegate hosing to a fluid line connecting
side-socket.
[2582] Completely separate and independent use is always preferred
to external connection. For free manipulability, an ablation or
ablation and angioplasty-capable barrel-assembly is kept free from
outside connections, incorporating whatever electronic and fluidic
components are needed, so that insertion in the airgun is necessary
only to use the airgun linear positioning stage for precise
transluminal movement or to initiate or reinitiate the discharge of
medication or stenting miniballs. The use of lithium ion or
thin-film batteries gains interior space. Small cylinders of
pressurized gas are mounted on the barrel-assembly and attached
directly to the end or side-socket as applicable.
[2583] When tethering is unavoidable, as when an outside sources of
gas that uses a large cylinder or an auxiliary apparatus such as a
laser or rotational atherectomy tool that uses its own control
console is required, interference with free movement is minimized
through the use of a side-socket having electrical connectors, a
portal for admitting a fluid hose, and fluid couplings as
necessary. A side-socket is preferred to an end-socket or plug at
or beside the terminal plate as allowing the proximal end of the
barrel-catheter to be freely entered and removed from the airgun so
that the delivery of s gas or continued use of an external device
can continue without interruption whenever the barrel-assembly is
inserted into or removed from the airgun.
[2584] With the incorporation of a side-scoket for electrical
and/or fluid connection, insertion or removal of the
barrel-assembly from the airgun has no affect on the delivery of
power and fluids. If power is taken by connection within the airgun
chamber to the airgun power supply, then to be able to remove the
barrel-assembly without losing power necessitates that the
barrel-assembly remain tethered to the airgun through an electrical
cord that is connected to the barrel-assembly by means of a
side-socket, usually one that includes both electrical and fluid
connections. A barrel-assembly that is meant only for implantation
discharge must still have a source of power for a recovery
electromagnet that must be available to retrieve any misplaced or
loose miniballs.
[2585] Since such a barrel-assembly is never used independently of
an airgun, it draws power through the airgun chamber. The loss of
an implant within the vascular tree unacceptable, means are
provided to minimize the risk of such an eventuality and to recover
the implant. Every barrel-assembly to be described is equipped with
at least recovery electromagnets for retrieving loose and
extracting mispositioned implants. The miniball recovery
electromagnet or electromagnets in a simple, or ablation or
angioplasty-incapable barrel-assembly, are electrically connected
to the airgun power supply upon engagement of its proximal end in
the airgun chamber.
[2586] The current to the recovery electromagnets in a simple
barrel-assembly is accordingly controlled from the airgun control
panel. Unlike a simple or incapable embodiment, a
noncombination-form ablation or ablation and angioplasty-capable
barrel-assembly not requiring outside connection must be capable of
use as a self-contained apparatus. Incorporating radial projection
units that must accommodate tool-inserts capable of different
processes which must be coordinated, such a barrel-assembly
requires its own onboard control panel. When only used to perform
either an angioplasty or to introduce intraductal implants,
conventional means are employed to perform the other procedure.
[2587] When the implants must be spaced too closely together for
discharge to be controlled by hand, a positional control system is
used to effect discharge automatically. Whereas ablation and
ablation and angioplasty-capable barrel-assemblies can ablate or
angioplasty as well as discharge implants, a stay insertion tool
can only be used to introduce implants. When stenting is
uninvolved, both miniball and stay implants can consist entirely of
medication and/or irradiating seeds. The medication can be
antiangiogenic, proangiogenic, proneurogenic, chemotherapeutic,
oncolytic viral, antibiotic, nanotechnological, or gene
therapeutic, and released at a controlled rate so that delivery is
closely targeted for the diseased tissue. Outside of the
circulatory system, the recovery of implants is seldom an emergency
and accomplished readily.
[2588] Usually too small in diameter to induce a cerebral or
myocardial infarction in an artery of exclusive or nonoverlapping
territory with platelet blockade administered, the miniball
implants used are of sizes as would result in end-circulation
foreign body embolism were any to escape into the bloodstream (see,
for example, Macdonald, R. L., Kowalczuk, A., and Johns, L. 1995.
"Emboli Enter Penetrating Arteries of Monkey Brain in Relation to
their Size," Stroke 26(7):1247-1251; Fisher, C. M. 1969. "The
Arterial Lesions Underlying Lacunes," Acta Neuropathologica
12(1):1-15; Agranoff, A. B. and Wong, E. H. 2006. "Lacunar Stroke,"
http://www.emedicine.com/pmr/topic63.htm), making it imperative
that means be incorporated into the muzzle-head to prevent such
losses. Emergency extraction of an embolizing miniball is addressed
in section X2c below entitled Stereotactic Arrest and Extraction of
a Circulating, Dangerously Positioned, or Embolizing Miniball.
[2589] For this reason as well as to intentionally retract a
mispositioned miniball after implantation, the muzzle-head of a
radial discharge barrel-assembly for use in the bloodstream always
includes a recovery and extraction miniball electromagnet assembly
supported by a trap-filter, both of which run ahead, that is, are
positioned distal to the muzzle-ports or holes through which the
miniballs are projected and can usually remain energized during
discharge. Recovery can also be accomplished by connection of a
barrel-tube or the entire proximal end of the barrel-assembly to a
vacuum pump, as addressed below in the section entitled Muzzle-head
Access by Means of a Service-channel. Each of the diametrically
oriented recovery electromagnets in the pair is separately
controllable.
[2590] To allow the electromagnets to be deenergized (turned off)
when not needed or to avoid the risk of unintentionally retracting
a miniball that has been successfully implanted, each electromagnet
is situated behind a spring-loaded plastic trap door that is pushed
aside (inward) by the miniball as it is drawn toward the magnet.
Once in the magnet-trap, or magnet antechamber, the spring closes
the door behind, trapping the miniball in the magnet-trap allowing
the magnet to be deenergized. To minimize the likelihood for the
drawing of a miniball toward a magnet so that rather than to find
its way through the trap door it becomes forcibly held or stuck
against the outside of the muzzle-head requiring that the magnet be
deenergized to release it, the area of the trap doors, or the
doorway should be as large as possible to provide the least
obstructed opening before the lines of force which are
substantially oriented behind and across the doorway.
[2591] Recovery of the miniball necessitates either keeping the
magnet fully energized until the barrel-assembly is withdrawn or
energizing the other recovery electromagnet at the same instant
that the magnet behind the missed doorway is deenergized in to draw
the miniball into the contralateral magnet-trap. The turret-motor
allows rotation of the muzzle-head to assist in this process.
However, either of these actions will interfere with the ongoing
procedure. Yet another way to retrieve a miniball is by connecting
one or more barrel-tubes or the distal end of the barrel-assembly
to a suction pump and vacuuming the miniball to the outside.
[2592] This technique is more appropriate for a simple pipe type
barrel-assembly that lacks a turret-motor to allow rotation of the
recovery electromagnet. A barrel-assembly that lacks a side entry
socket or sockets as addressed below in the section entitled
Muzzle-head Access through a Service-channel without the Aid of and
by Means of Inserting a Service-catheter must be disconnected from
the airgun. While a miniball adherent thus in the digestive tract,
for example, would be without significance and simply released into
the lumen, and one in a ureter, for example, would have to be too
large in diameter to be spontaneously voided, this must never
happen in the circulatory system.
[2593] In the airway, where usually a simple pipe type
barrel-assembly without trap-filter is used, the recovery
electromagnet is deenergised so that the miniball sticks along the
surface of the lumen. Provided the miniballs have been wetted with
contrast on the rotary magazine clip prior to insertion of the clip
into the chamber, recovery of the miniball through the recovery
electromagnet trap-door is a simple matter. It has already been
stated that no barrel-assembly introduced into the vascular tree
should lack a trap-filter, as addressed below in the section
entitled Embolic Trap Filter in Radial Discharge Muzzle-heads for
Use in the Vascular Tree.
[2594] VII2. Ablation and Angioplasty-Incapable
Barrel-Assemblies
[2595] An ablation or angioplasty-incapable barrel-assembly is a
catheter extension to the barrel of an interventional airgun that
remains engaged in the airgun and is used for medication miniball
and/or stent miniball implantation. Ablation or
angioplasty-incapable barrel-assemblies consist of simple pipe and
radial discharge type barrel-assemblies. The simple pipe is
substantially limited to use in the airway, the exceptions being
use in the esophagus or gut when larger in diameter. The radial
discharge type is meant for use in bloodless ductus wherein the
anatomy is not highly differentiated as it is in the airway. The
features incorporated into a radial discharge barrel-assembly
usually include a trap-filter, electrically heatable turret-motor
and recovery electromagnet windings with overlying heat-windows,
and nonpiped, or electrically operated, radial projection
units.
[2596] To allow piped or fluidically operated radial projection
units to remain connected with the barrel-assembly engaged in the
airgun or worked by hand, the fluid store and controls are usually
attached by means of an end or side-socket (qv.), usually through
lines to a remote canister and controls. The extent of fluid
circuit internalization, variable, an entirely self-contained
embodiment must include a miniaturized fluid reservoir and pump.
Miniaturized fluid supply and pumping modules that attach to the
barrel-assembly without the need for hoses connected to remote
apparatus also free movement. A simple pipe or a radial discharge
barrel-assembly without supplementation can only be used to implant
miniballs.
[2597] However, miniballs can consist, for example, mostly of
ferrous metal to serve as the intraductal component of an
extraluminal stent, or almost entirely of medication and/or other
therapeutic substances where stenting is uninvolved and
implantation can be closely targeted. Ensheathing a simple pipe or
a radial discharge barrel-assembly within the central channel of a
combination-form radial projection catheter adds side-looking tools
for ablation or angioplasty by cutting, abrading, heating, or
chilling, or injecting any fluid substance into the lumen wall. The
combination-form radial projection catheter is slid over the
barrel-assembly beginning at the proximal end until the front or
distal edge of the catheter is stopped by the muzzle-head.
[2598] The combined apparatus is effectively an ablation or an
ablation and angioplasty-capable barrel-assembly that requires
insertion into an airgun only during ballistic discharge. Except
for stenting without angioplasty, addressed below in the section
entitled Thermal Ablation or Angioplasty- (Lumen Wall Priming
Searing- or Cautery-) capable Barrel-assemblies, now gaining some
acceptance, to minimize the risks for plaque rupture and the
release of embolizing debris by contact with the muzzle-head, an
ablation or angioplasty-incapable barrel-assembly is meant for use
in an artery only following an angioplasty or an atherectomy.
[2599] An ablation and angioplasty-capable barrel-assembly allowing
both angioplasty and stenting discharge with single entry, an
angioplasty or atherectomy preceding the use of an ablation or
angioplasty-incapable barrel-assembly requires the use of prior art
(conventional) means or a separate radial projection catheter as
addressed below in the section of like title. Such
barrel-assemblies generally include or make possible plural means
for the recovery of a loose miniball, to include recovery
electromagnets, which can be reoriented in rotational angle with
the turret-motor and transluminally by hand or a linear stage, a
trap-filter, and the attachment of a barrel-tube or the proximal
end of the barrel-assembly as a whole to a vacuum pump.
[2600] The attachment of a barrel-tube or tubes to a pump without
the need to remove the barrel-assembly from the airgun is made
possible by incorporation of a side entry socket, as addressed
below in the section entitled Muzzle-head Access by Means of a
Service-channel. Intended for use mostly in ductus other than
vascular, the use of an an ablation or angioplasty-incapable
barrel-assembly in the arterial tree to stent without an antecedent
angioplasty, even with the addition of a distal embolic protective
filter, is specifically renounced as risking the release of
embolizing debris. Ablation or angioplasty-incapable
barrel-assemblies include simple pipes and radial discharge mono-
and multibarrel radial discharge barrel-assemblies.
[2601] No independent (intrinsic, inmate) thermal ablative or
angioplasty means are incorporated to allow use as separate from
the airgun for freedom of movement, and no on-board electrical
components or connections for independent power or control are
installed. However, as the turret-motor is required positionally
and the recovery electromagnets are required to retrieve dropped or
to extract misplaced miniballs during implantation discharge,
ablation or angioplasty-incapable barrel-assemblies require
electrical connection to the airgun power supply, and this is
accomplished through the types of contacts shown in FIGS. 55 and
58.
[2602] The incorporation of radial projection units into the
muzzle-head of an ablation or angioplasty-incapable barrel-assembly
imparts a radial nudging capability as a part of positional control
rather than serves an ablative or angioplastic function. Because a
minimally capable ablation and angioplasty barrel-assembly will
generally include few radial projection units for deploying various
side-cutting (side-shaving), side-brushing (side-sweeping), and/or
side-injecting tool-inserts (addressed below in the section
entitled Radial Projection Units, et sequens), it will generally
lack an on-board ablation and angioplasty control panel. A
relatively simple control for deploying radial projection unit
tool-inserts, for example, is then included in the positioning and
discharge control panel on the airgun enclosure.
[2603] For this reason, when an ablation or ablation and
angioplasty-capable barrel-assembly is used, the radial projection
unit tool-insert lift-platforms can be deployed from either the
ablation-angioplasty control panel on-board the barrel-assembly or
the positional and discharge control panel mounted to the cabinet
of the airgun. The use of controls on the component controlled
reduces human error. Conversely, because insertion in the airgun
prevents free and independent movement unless the electrical
connections are by means of a side-socket as addressed below in the
section entitled Barrel-assembly Side-socket and graphically
depicted in FIG. 58 and there is sufficient slack (and not as shown
in FIG. 55), an ablation or ablation and angioplasty-capable
barrel-assembly is used for ablation or angioplasty before
engagement in the airgun.
[2604] Therefore, the positional controls mounted to the airgun
would not usually be those used to rotate an eccentric turret-motor
slot or slit heat-window or to eccentrically deploy radial
projection units during ablation or atherectomy. The controls for
these are on-board the free-standing ablation or ablation and
angioplasty-capable barrel-assembly, preferably on top of the power
and control housing for ambidextrous use.
[2605] VII2a. Simple Pipe Barrel-Assemblies
[2606] When the anatomy within the lumen, such as in the trachea,
is structurally differentiated necessitating the discriminatory
placement of each implant and the distances separating successive
discharges are large enough for manual placement, automatic
transluminal movement and triggering in uniform measured increments
as is appropriate in a structurally undifferentiated lumen of small
diameter is unsuitable. The simple pipe type barrel-assembly is
intended for targeted implantation in a surgically entered body
cavity or in a ductus or vas that is open to the exterior and large
enough to allow the muzzle-head to be maneuvered without the need
for repeated withdrawal and reentry.
[2607] Since application in a structured lumen demands accuracy, a
flexible endoscope, usually a fine fiberoptic angioscope, and laser
sight or pointer are lashed or clipped alongside the
barrel-assembly, the laser sight used to mark the target, with the
endoscopic view displayed on a monitor. If a bounce-plate is used,
these viewing means are provided to cover it as well. A simple pipe
barrel-assembly consists of barrel-catheter 44 with muzzle-head 45
having a mildly arcuate or curved section toward its distal
underside containing the recovery electromagnet 46 in housing 56
within electromagnet housing 56 that the operator can bend if
necessary toward the distal end to direct the miniballs toward the
tissue, usually at an angle of about 35 degrees.
[2608] In simple pipe and single miniball radial discharge
barrel-assemblies, the barrel-catheter and barrel-tube are one and
the same, except that the barrel-tube or tubes continue all the way
to the exit-hole, whereas the polymeric barrel-catheter terminates
and is joined to the usually nonmagnetic stainless steel
muzzle-head at the distal end. To avert the completion of a closed
magnetic circuit that would detract from the field strength
available for the purpose of miniball recovery as well as to allow
the muzzle-head to be straightened if desired, muzzle-head 45 is
made of forcibly bendable nonferrous metal or nonmagnetic stainless
steel tubing and magnet housing 56 of any suitable plastic.
[2609] For better `feel,` that is, a firmer grip, or a sense of
greater substantiality and security, especially along the proximal
segment mounting the control, thin simple pipes can be built up in
diameter. This is accomplished by applying a molded hand-grip or by
passing a concentric thick walled catheter made about the
barrel-assembly or a combination of catheters that match and
friction fit in concentric external to internal diametric relation.
Over the intracorporeal segment, the outermost catheter is made of
a soft polymer, such as a thermoplastic polyurethane or silicone.
The muzzle-head of the simple pipe curved, a bounce-plate allows
the miniball trajectory to be deflected into another direction.
[2610] Any protrusion of the angle adjusting mechanism or its parts
that would scratch or gouge the lumen wall is kept to the minimum,
rounded, and softened. A simple pipe as shown in FIGS. 31 thru 33
consists of barrel-catheter 44 with nonmagnetic metal muzzle-head
45 connected at the distal working end. To minimize friction,
barrel-catheter 44 ordinarily has a fluoropolymer lining and is
coextruded with or laminated by heat-shrinking and/or bonding
ensheathment within a polymeric outer layer or layers selected to
impart only so much flexibility as allows the operator essential
working maneuverability while minimizing sagging as detracts from
exit velocity.
[2611] Rotary joint 133 allows muzzle-head 45 to be rotated without
twisting barrel-catheter 44. For laparoscopic use when muzzle-head
45 is short enough, rotary joint 133 connects barrel-catheter to
muzzle-head 45; otherwise rotary joint 133 is placed along
barrel-catheter 44. Muzzle-head 45 is made of nonferrous metal such
as copper or an austenitic or nickel-containing 300 series
nonmagnetic stainless steel steel with a hardness and wall
thickness as allows the operator to adjust the aim by bending it at
the distal curve. Magnet housing 56 can have an upper surface with
a channel to receive the muzzle-head tube and be fastened to the
underside of the muzzle-head by resistance welds limited to its
proximal portion so that the muzzle-head can be bent to a less
curved angle without disconnecting the magnet housing.
[2612] The housing then serves as a cold bending form to return the
muzzle-head to its fully curved conformation. The muzzle-head of a
radial discharge barrel-assembly is always controlled remotely with
the turret-motor for rotation, for example. In a simple pipe for
use through a laparoscopic portal, the muzzle-head can attach to
the barrel-catheter at an internally smooth rotary joint that
extends outside the body, allowing the operator to rotate the
muzzle-head as a handpiece. This does not apply to a simple pipe
for use in the airway, where the rigid and anatomically
noncompliant muzzle-head must be limited to a short distal segment.
Housing 56 for the trap and extraction, or recovery, electromagnet
46, is fixed in position within the concavity or intrados described
by the underside of curve 45.
[2613] Inserting barrel-catheter 45 into barrel 57 of the airgun
and locking engagement within the airgun chamber is by means of
annular flange twist-to-lock connection fitting 47 in FIGS. 31 and
32, with detail provided in FIG. 73 establishes mechanical
connection, with electrical connection to the airgun power supply
established by an end- or terminal plate of the kind shown in
detail in FIG. 72. Flange component 103 of the twist-to-lock
connector fitted to the end of the airgun muzzle is friction fit to
allow it to be rotated, so that to insert the barrel-assembly into
the airgun after an angioplasty has been performed with the
barrel-assembly already intraluminal and still separate from the
airgun does not require rotation of the barrel-assembly in the
lumen.
[2614] The equivalent connection with a radial discharge
barrel-assembly shown as part 75 in FIGS. 39, 73 thru 75, and 78
can be freely rotated with a single barrel-tube barrel-assembly or
monobarrel; however, the rotation of a radial discharge
barrel-assembly having plural barrel-tubes at this joint may
require that the rotary magazine clip also be rotated. The
connecting flange can be forcibly rotated, but when different type
miniballs, such as some pure medication and others ferromagnetic,
are placed in each hole of the rotary clip, each must be discharged
through the barrel-tube respective of each hole for aiming at the
point of infixion intended. To accomplish the correct alignment
between each barrel-tube and the hole in the clip respective of
each barrel-tube may require manually rotating or indexing the
rotary clip into the required position.
[2615] To maintain the correct alignment over consecutive
discharges, the holes in the rotary clip are numbered to match the
numbers assigned to the barrel-tubes. To allow the operator to
slightly bend the muzzle-head when necessary, recovery
electromagnet housing 56 is fastened to the underside of the
muzzle-head 45 only along its more proximal upper surface interface
with muzzle-head 45. Directly manipulated rather than remotely
controlled by a positional control system, the simple pipe
barrel-assembly is suitable for use in larger ductus that can be
implanted with larger and more sparsely spaced miniballs with
relatively little risk of pull-through.
[2616] In FIGS. 31, 32, and 34, in a simple pipe for use with
laparascopic entry so that the muzzle-head 45 extends outside the
body, muzzle-head 45 is joined to barrel-catheter 44 to serve as a
handpiece which the operator can grasp and rotate by internally
smooth rotary joint 133. In FIGS. 31 thru 33, rotary joint 133 is
included only when the torsional resistance of barrel-catheter 44
hinders rotation of the muzzle-head or the lack thereof allows
twisting deformation of barrel-catheter 44. Rotary joint 133 must
rotate smoothly to allow the rotational angle to be set precisely
and not be so loose that it then deviates or rotates unless a
twisting force is applied to it.
[2617] In a simple pipe for use in the airway, where forcibly
bendable but otherwise rigid muzzle-head 45 must be short as not to
injure the, vocal folds (vocal cords, vocal ligaments), larynx, or
airway, and cannot extend outside the body, joint 133 cannot join
the muzzle-head to the barrel-catheter but must be positioned
farther proximally along the barrel-catheter to provide a rotatable
handpiece. This makes barrel-catheter 44 relatively long compared
to muzzle-head 45, so that even though barrel-catheter 44 is made
of or lined with a low friction fluoropolymer, such as
polytetrafluoroethylene of relatively high torsional stiffness
(ratio of applied torsion moment to resultant twisting),
muzzle-head 45 can usually be rotated with little resistance as
would interfere with accurate aiming. If not, a rotary joint is
placed along barrel-catheter 44.
[2618] The simple pipe is intended primarily for use with a
specially adapted relatively low cost air pistol for the treatment
of tracheal collapse in veterinary practice. When the overall
extent of transluminal or intracavitary travel is small and/or an
assistant available, the barrel-assembly is connected to the airgun
without an antisag-antiveer linkage as shown in FIG. 78 and
described below in the section entitled Forward Drive and Sag
Leveling and Stabilizing Device. When needed, the linkage is
fastened at the airgun muzzle to extend over the barrel-catheter
and keep it from sagging, veering, or buckling. The use of a
continuous metal tube as barrel-catheter with a rotary joint to
define and allow rotation of the distal segment as a muzzle-head
avoids the expense of an antisag linkage but is too stiff to afford
the operator any freedom of movement.
[2619] To minimize the risk of scrapes or gouges, the distal end of
muzzle-head 45 is surrounded by elastomeric guard annulus 52, which
covers the sharp edge of exit-hole (exit-port, ejection port) 55.
Miniball recovery electromagnet housing 56 is nested within the
mild curve toward the distal end of muzzle-head 45. The pipe is
passed down the airway or through a laparoscopic entry portal with
retractor or cannula to the treatment site. When the simple pipe is
connected to a modified air pistol (hand airgun, air handgun) as
described under the section below entitled Modification of
Commercial Airguns, the gun, whether slid along a table top
adjusted to the height of patient entry or held by an assistant, is
allowed to move freely, and when the operator indicates that he is
about to depress the trigger, the assistant is given a brief
interval during which to make certain that the barrel-catheter is
straight.
[2620] The barrel-catheter is not pulled straight as would displace
the aimed muzzle-port but rather held level at the midpoint where
it sags, the gun retracted only so much as is necessary to take up
the slack. When the simple pipe is connected to an interventional
airgun as described under the section below entitled Dedicated
Interventional Airguns, the airgun is mounted on a wheeled tray or
small dolly set on a table top adjusted to the height of patient
entry, which the assistant allows to roll freely for the operator
to indicate that he is about ready to trigger discharge, the
assistant moving the table as well if necessary. When the operator
indicates the intention to trigger discharge, the assistant assures
that the barrel-catheter is straight and level by supporting the
sag by hand and retracting the airgun only so much as is necessary
to take up the slack.
[2621] The simple pipe can also be adjusted in sag or lateral
curvature intentionally to reduce the exit velocity; however, this
must never be done without first testing the airgun as described
below with each such bend, and since to do this will require
disconnecting the barrel-assembly from the airgun, such use in not
preferred to adjustment that uses the sliding valve modification
applied to the valve body also described below under the section
entitled Modification of Commercial Airguns. When the veterinary
patient with collapsed trachea is so small that the curve cannot be
reduced sufficiently to avoid laryngeal injury, a radial discharge
barrel-assembly with extracorporeal hand-held electromagnet should
be considered.
[2622] If no barrel-assembly appears usable, then arcuate stays
with a stent-jacket should be considered before proceeding with the
standard procedure for suturing prosthetic rings about the trachea.
For collapse that extends into the bronchi in tiny patients,
implantation by means of a radial discharge barrel-assembly
(addressed below) combined with subcutaneous patch-magnets
(addressed above) is preferable as negligible in level of trauma
compared to a thoracotomy. Procedures for correcting and
ameliorating the symptoms of tracheal collapse are described below.
While demanding more operative time, a simple pipe with modified
commercial air pistol is adequate and inexpensive compared to more
complex barrel-assemblies and special-purpose interventional
airguns.
[2623] The combination of barrel-assembly and air pistol is
primarily intended for use by veterinarians to repair tracheal
collapse in small dogs. The simple pipe can also be used in a
normally closed vessel or duct where accidental injury or a primary
procedure has given access. Unlike a multibarrel radial discharge
barrel-assembly, the simple pipe lends itself to loading from a
spring-loaded or gravity-fed linear or queue-type no less than a
rotary magazine clip. The limited diameter of most ductus makes a
barrel-assembly with a single barrel radial discharge muzzle-head
imperative to achieve an outer diameter of two millimeters.
Otherwise, such an embodiment is not intended for use in any closed
ductus and less still in the vasculature.
[2624] The airway does not pose the problems associated with the
bloodsteam, which include the need to prevent the backflow or entry
of blood into the muzzle-head, and the risks of introducing gas
into the blood, stretching injury, and inducing ischemia by
obstructing the flow of blood. These factors and severely limited
working room demand a speed of operation that the substantially
undifferentiated structure of the lumen wall makes feasible. The
simple pipe is suited to aiming within a lumen that is
differentiated in structure, where speed is important but not of
the essence, and requires no peripheral blood-grooves, tunnels, or
means for the equalization of internal pressure as is necessary in
radial discharge barrel-assemblies suitable for use in the vascular
tree as described below. The treatment of tracheal collapse is
addressed in greater detail below.
[2625] Multiple barrel barrel-assemblies with radial discharge
muzzle-heads suitable for use in the vascular system are discussed
thereafter. The simple pipe can be used with a flexible endoscope
lashed alongside it, marked with contrast such as tantalum-based
for viewability from without, or both. Unlike narrower ductus, the
trachea, bronchi, and gut, for which the simple pipe is intended,
are usually large enough to allow the elastomer bumper
guard-encircled muzzle-port at the distal tip to be rotated with
little risk of injury. Rotation is extracorporeal, the omission of
a turret-motor allowing the muzzle-head to be narrower. If the
lumen is too narrow for a simple pipe, a radial discharge
barrel-assembly with protective outer shell and turret-motor is
used.
[2626] The patient supine, or recumbent, loose miniballs stick to
the lumen floor, and are retrieved either with the tractive
electromagnet contained within recovery magnet housing 56 in the
underside concavity of the muzzle-head seen in FIGS. 31 thru 34, or
by connecting the distal end of the barrel-assembly to an
aspiration pump. An aspiration line side-socket as addressed below
in the section entitled Barrel-assembly Side-socket, or coupling
mounted to the side of the barrel-catheter close to the airgun
muzzle, allows the barrel-assembly to remain connected to an
aspiration pump without the need to disengage the barrel-assembly
from the airgun. Shown in FIG. 33, spring-loaded trap-doors to
either side of the recovery electromagnet are opened inward by the
force of a loose miniball that is pulled into the housing, thus
minimizing the rotation necessary to recover a loose or
mispositioned miniball.
[2627] For the purpose of aiming implants, however, the muzzle-head
of a simple pipe should rotate by not less than 120 degrees to
either side with little resistance. Using a simple pipe
barrel-assembly to treat a tracheal collapse, for example, the
patient is positioned supine and the `swing` to either side of
straight downwards allows the placement of implants alongside the
dorsal membrane to suspend it as addressed below in the section
entitled Procedure for the Palliation of Tracheal Collapse in a
Small Dog, among others. The patient is longitudinally rotated
("logrolled," rolled) into the supine position for the procedure
before the simple pipe is introduced. This is not always necesssary
with a radial discharge barrel-assembly, which has a slippery (low
friction) protective shell enclosing the muzzle-port (miniball
exit-hole) or ports.
[2628] To reduce the width of the working end of the muzzle-head in
a simple pipe type barrel-assembly, a single larger recovery
electromagnet as shown in FIG. 33 is preferred. The inward-opening
trap-doors to either side of the magnet are not shown as situated
to the rear and fore of the plane of the drawing. Even though a
simple pipe type barrel-assembly is primarily intended for use in
the airway with the patient supine so that a loose contrast-wetted
miniball sticks to the lumen surface where it is easily located,
the side trap doors are made as large as possible to provide
minimal obstruction to the most convergent lines of force that pass
behind and across behind the doorways.
[2629] If, for example, the simple pipe is made of a substantially
if not perfectly nonmagnetic stainless steel on the outside with an
internal coating of polytetrafluoroethylene and the electromagnet
housing 56 is made of a pliable polystyrene, then a suitable
adhesive is a two part polyurethane, such as Loctite U-05FL, part
number 29348, applied with mixer nozzle part number 98454 and
dispensing gun part number 98472. Allowing some pliancy makes it
possible for the operator to slightly bend the pipe at the curve if
necessary. If altered, the pipe must be tested to ascertain the
effect upon the exit velocity and consequent need to adjust the
controls before use.
[2630] The simplest and most direct test is that described below in
the section below entitled In situ Test on Endoluminal Approach for
Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation. This universal connector for engaging a
barrel-assembly in the barrel of an airgun, which differs only in
diameter for Barrel-assemblies which contain multiple barrel-tubes,
is described below under the section on the mechanical connection
of the barrel-assembly to the airgun, and is shown in FIGS. 31, 32,
74, 75, and 78. This connector is the same as that used with radial
discharge barrel-assemblies of which a detailed view is shown in
FIG. 73. Should the detailed structure require, or the operator
determine, that a second pass to implant miniballs in the reverse
direction is needed, a bounce-plate is required.
[2631] A simple pipe with an integral or built in intracorporeally
controllable bounce-plate allows the deployment, retraction, and
angular adjustment in rebound angle without the need to withdraw
and reintroduce the barrel-assembly. A bounce-plate attachment
requires that the barrel-assembly be withdrawn to add, remove, or
adjust the bounce-plate by bending before it is reintroduced. As an
isolated occurrence, this is tolerable; however, repeated
withdrawal and reentry is to be avoided as risking injury. A simple
pipe is shown without a bounce-plate in FIG. 31, and with a
bounce-plate attachment as addressed below in the section entitled
Intracorporeally Nondeployable nor Adjustable Bounce plate
Attachment and shown in FIG. 34. in FIG. 32, with intracorporeally
controllable types shown in FIGS. 35 thru 37.
[2632] Bounce-plates which can be positioned from outside the body
are described below in the sections entitled Intracorporeally
Deployable and Rotatable Bounce plate with Slightly Adjustable
Rebound Elevation and Intracorporeally Deployable and Rotatable
Bounce plate with Precision Adjustable Rebound Elevation. A
bounce-plate attachment, as opposed to a controllable bounce-plate
addressed below in the sections entitled Extracorporeally
Deployable Fixed Angle Bounce plate and Extracorporeally Deployable
Adjustable Angle Bounce-plate, is made of a suitable plastic or a
nonferrous metal such as copper or aluminum. As seen in greater
detail in FIG. 34, in which the trajectory is represented as 54 and
the distal end of the original muzzle-head 55 over which the
bounce-plate has been slid, extends proximally along the top and
sides of the barrel-catheter to a length sufficient to minimize if
not eliminate recoil upon discharge, which length depends upon the
material of which the barrel-catheter is made.
[2633] The simple pipe can be produced with an endoscope or with
smooth surfaced clips for attaching an endoscope or similarly
configured device,such as a laser or hot or cold air line. The
endoscope is readily incorporated regardless of whether an
endoluminal deflection-plate control mechanism as described below
in the section entitled Inracorporeally Deployable and Rotatable
Bounce plates is also present. Simple pipe barrel-assemblies for
miniballs of 1 to 4 millimeters in outer diameter are made easier
to manipulate if grips or an outer casing is added. For short
segments, tape can be wrapped around the barrel-catheter.
[2634] To cover a longer segment, a catheter or catheters made of a
soft polymer material such as silicone rubber latex that match in
internal to external diameter as allows snugness in concentric
relation are used. Referring now to FIGS. 31 and 32, shown are
simple pipe type barrel-assemblies engaged in airguns. However, an
intracorporeally deployable and rotatable bounce-plate, as
addressed below in the section of like title, is sufficiently
pliant and unobtrusive that it can extend from its distal end above
the exit-hole backward (proximad) past the rotary joint, to a
control slide-box that extends outside the body.
[2635] The distal portion of the barrel-assembly is curved to allow
a miniball to be implanted, in tracheal application as will be
described, at the anterior junction of each successive cartilage
ring with the annular ligament, bilaterally, along imaginary lines
that would demarcate the lateral edges of the dorsal quadrant of
the trachea were it circular. Trap-extraction electromagnet 46 in
FIG. 33 is of the same construction and electrical connection as is
specified below for radial discharge muzzle-heads, but is singular,
and as visualized in longitudinal cross-section, directed radially
toward the tissue rather than paired where each is separately or
jointly adjustable in field strength.
[2636] VII2b. Simple Pipe Ablation and Angioplasty-Incapable
Barrel-Assembly Muzzle-Heads
[2637] VII2b(1). Simple Pipe Barrel-Assembly with Bounce-Plate
[2638] A barrel-assembly for use in the vascular tree must present
a smooth and slippery surface, allow quick operation as one means
for minimizing hypoxia, and incorporate features that minimize if
not eliminate the need for withdrawal and reentry. This fact and
the need to avoid any projections prompts enclosing the
barrel-tubes of a radial discharge barrel-assembly in a slippery
torpedo-shaped shell which is internally as well as externally
protective in virtually eliminating gouging, incisions, and
perforations, is position stabilizing, and strengthening. Compared
to the structured trachea, the relatively undifferentiated gross
structure of vascular, gastrointestinal, and urinogenital lumina
lend themselves to multiple radial discharge, which places two or
more miniballs at different radial angles with each discharge.
[2639] By contrast, the placement of miniballs in the trachea must
be discretionary such that each miniball can be aimed at a specific
point. This requires a single barrel that is not enclosed within a
shell and can be clearly seen. A fine-gauged fiberoptic endoscope
or angioscope and laser sight or pointer clipped alongside the
barrel-assembly provide a view of the target site and indicate the
aiming point for implantation that allows discharge to be accurate.
FIG. 31 shows a simple pipe type barrel-assembly without a
bounce-plate (deflection-plates, ricochet-plates; rebound-tips;
rebound-plates, rebound deflection-plates, rebound angle deflection
plates), and FIG. 32 shows one with an attachable bounce-plate,
these embodiments omitting an intracorporeally controllable
bounce-plate mechanism fastened along the upper surface toward the
distal end of the pipe as shown in FIG. 35.
[2640] The portion of the barrel-assembly distal to the
barrel-catheter 44 is muzzle-head 45. Optionally, to allow slight
shifts or deviations in the aiming point or the point at which the
miniball will penetrate the target tissue, the proximal face of a
bounce-plate which is struck can be formed or ground with a concave
contour. The concavity can be along the vertical or the horizontal
axis or both. The controls provide calibrated gauges to support
this capability. Unlike a radial discharge barrel-assembly, which
can only be rotated over an arc determined by the eventual twisting
of its barrel-tube or tubes, rotatory joint 133 allows muzzle-head
45 to be rotated endlessly. In a barrel-assembly for use without a
bounce-plate or with a bounce-plate attachment described below,
rotatory or swivel joint 133 must be placed at a level sufficiently
proximal to allow muzzle-head 45 to be rotated in relation to the
barrel-catheter.
[2641] In a barrel-assembly with an intracorporeally controllable
bounce-plate mechanism described below, rotatory joint 133 must
also be placed sufficiently proximal to allow clear access to the
bounce-plate mechanism controls, which must be mounted to the top
of muzzle-head 45 with which the mechanism rotates. The patient
under general anesthesia, provided muzzle-head 45, which is
inflexible from the distal (front) end to rotary joint 133 and
includes a slight curvature toward the front end with recovery
electromagnet 46 within magnet housing 56 nested therein can be
passed through the vocal folds and larynx, for example with little
risk of injury, rotary joint 133 will join muzzle-head 45 to
barrel-catheter 44.
[2642] However, if the inflexibility of the muzzle-head interferes
with safe clearance, then rotary joint 133 is placed more
proximally to divide rather than join barrel-catheter 44 to
muzzle-head 45. In this case, the materials of a bounce-plate
mechanism must be flexible to comply with that of the
barrel-catheter, which is readily accomplished with many different
materials using a bevel gear but not a pulley arrangement within
control tube 135 shown in FIG. 37. The division of the control
sleeve into a proximal control slide-box portion 134 and distal
controlled slide-box portion 140 is due to the requirement for
control rod 135 to be rotatable, hence, cylindrical, whereas the
distal bounce-plate 53 must have bilateral extension. Continuous
sleeve or separate slide boxes 134 and 140 can be made of any
suitable nonmagnetic metal or plastic with all corners and edges
rounded or blunted.
[2643] Control slide-box 134 is lined with a material such as felt
that imparts a smooth sliding action to slide-block 137, while
controlled slide-box 140 is lined with an absorbent material such
as gauze or a nonallergenic foam which can be wetted with a
mucolytic such as acetylcysteine or a mucinolytic (mucinase,
mucopolysaccharidase). The absolute amount of acetylcysteine is too
small to cause stomatitis or induce nausea or rhinorrhea; however,
to prevent bronchospasm, only light wetting isused in the distal
airway. When made continuous, the proximal lumen must be circular
to allow control tube 135 to be rotated, while the lumen of the
distal controlled slide-box 140 must be horizontal to accommodate
bounce-plate 53.
[2644] Thus, a lumen uniform in diameter or gauge from end to end
would have to equal the width of bounce-plate 53, which will most
often equal the diameter of exit-hole 55. This would double the
cross-sectional area of muzzle-head 45 and bounce-plate mechanism
combination. Fundamental objects being to minimize the muzzle-head
to miniball diameter ratio and cost, separate proximal and distal
lumina or slideways are provided as control slide-box 134 and
controlled slide-box 140. The proximal end of bounce-plate control
slide-box 134 then spans across a nonrotatable and intracorporeal
joint between the inflexible muzzle-head 45 and the distal end of
the barrel-catheter 44. Rotary joint 133 must then be sufficiently
proximal to allow the barrel-assembly distal to it to be rotated
and the bounce-plate to be controlled.
[2645] Since the bounce-plate mechanism does not span over rotary
joint 133, the muzzle-head remains endlessly rotatable.
Bounce-plates range in cost of manufacture and precision from a
simple attachment to a built in precision mechanism that allows the
discharge to be redirected without the need to move, much less
remove, the muzzle-head from the body. Located in the concavity on
the underside of the muzzle-head is the recovery electromagnet 46
within magnet housing 56. Rather than ejected perpendicularly to
the surface of the lumen wall, the miniballs are delivered at an
acute angle to be seated subadventitially or subfibrosally, or if
necessary, medially or submedically (superintimally).
[2646] Entry thus seeks to wedge the miniball in place and avoid
pull-through or delamination of tunic layers which may have been
weakened by disease. Discharge at an acute angle also avoids a
singular vector trajectory that normal to the intimal surface,
would be more prone to rebound, possibly back into the lumen, if
not perforate through the adventitia. For structured lumina or
where for any reason it is advisable to reverse the direction of
miniball entry, such as when entry orients the muzzle-head
retrograde so that the passage of contents might eventually urge
the miniball back into the lumen, a means for reversing the
direction of entry is desirable.
[2647] While in some instances, such as for treating the trachea in
a very small or `teacup` sized dog where a simple pipe is too large
for safe passage, an endoluminally deployable and retractable
bounce-plate mechanism of a types now to be described can be added
to a small gauge monobarrel radial discharge barrel-assembly.
However, radial discharge barrel-assemblies are ordinarily intended
for implanting substantially uniform gross anatomy as in virtually
every other type of ductus (ureters, gastrointestinal tract,
arteries) where exactitude in aiming is noncritical and multiple
miniballs can be discharged simultaneously. To allow a clearer view
of the exit-hole (muzzle), aiding aiming accuracy in relation to
the differentiated structure within the trachea, simple pipes omit
a shell (body, enclosure).
[2648] Barrel-assemblies for use within vessels, for example,
provide a shell about the muzzle-head to protect the lumen wall,
and are intended primarily for veterinary use to alleviate tracheal
collapse, although the same conformation makes simple pipes more
suited to applications outside of lumina than radial discharge
barrel-assemblies. Since a simple pipe barrel-assembly with the
endouminally deployable bounce-plate mechanism shown in FIG. 36 is
passed through the larynx and down the trachea if not a bronchus
with the bounce-plate retracted, a barrel-assembly that is equipped
with an endoluminally controllable bounce-plate mechanism also
reduces the risk of injury and thus the duration of general
anesthetization.
[2649] Simple pipes can be made 1. To accept a simple bounce-plate
attachment that to slip on and off requires removal from the
patient and to change the vertical angle (elevation) requires
bending and the rotational angle requires rotation of the
muzzle-head; 2. With a substantially fixed rebound angle
bounce-plate that can be slid forward into position or deployed and
rotated while endoluminal whenever needed; or 3. So that vertical
and rotational angular adjustments are under positive or direct
mechanical control and calibrated for precision. The latter two are
adjustable in downward inclination (elevation) of the bounce plate
and thus the angle of rebound along the vertical axis of the
muzzle-head.
[2650] By providing a calibrated control arm, that rotatable thus
allows fine adjustment in the angle of discharge through a wide
radially and longitudinally arcuate volume to its underside. When
the muzzle-head can be long enough to extend outside the body, the
forcibly bendable metal muzzle-head of the barrel-assembly is
joined at its proximal end to the barrel-catheter by an internally
smooth rotary joint for rotation as a handpiece. The
intracorporeally adjustable bounce-plate configurations shown in
FIGS. 35 thru 37 are then mounted to the upper surface of the
muzzle-head. If not, the control spans over the junction between
the muzzle-head and barrel-catheter. Either configuration allows
the bounce-plate to be controlled while the barrel-assembly is in
use to more quickly achieve fine control over the angle of
discharge.
[2651] To reduce the risk of injury, permanent endoluminal
bounce-plate control mechanisms must be as little protrusive as
possible and have outer edges and corners that are blunted
(rounded, curved). The use of a bounce-plate pertains only to
simple pipe, not radial discharge type barrel-assemblies. The
forward edge or rim of the pipe is generally cut an angle to allow
flush placement against tissue to be implanted. The overhang
generally accommodates the reverse discharge of miniballs when a
bounce- or rebound deflection plate is attached. To minimize
accidental injury, the tip of a simple pipe is covered with an
elastomer guard. Protruding beyond the tip of the simple pipe, an
overhang or roof-configured bounce-plate especially requires a
protective guard.
[2652] Likewise for flush abutment, the tip of a walled-around
bounce-plate is angled with the tip directed in the opposite
direction. Walled-around, Krummlauf-type continuously curved
barrels, and hybrid versions of the two for reversing the direction
of discharge would allow good control over the trajectory but are
impractical because of the enlargement if not hook conformation at
the distal end of the pipe. Such ends make insertion and withdrawal
difficult and more prone to cause laryngeal injury. The
bounce-plate can be a friction-fitting attachment or a permanent
feature. Because to observe the muzzle-port or ports is unintended
and more difficult with a barrel radial discharge barrel-assembly,
the simple pipe is preferred for use in the anatomically
differentiated airway.
[2653] The single barrel radial discharge barrel-assembly is used
only in the airway of the smallest dogs where there is not the
space to manipulate a simple pipe and in distal segments of the
bronchi where these are relatively undifferentiated. The structural
differentiation and consequent need to place the implants in a
discretionary manner can in some cases recommend the availability
of a simple pipe barrel-assembly with bounce-plate
(deflection-plate, ricochet-plate; rebound-tip; rebound-plate),
which allows reversing the direction of the trajectory, that is,
directing the miniballs back toward the operator or proximad. This
capability can be beneficial, for example, in the trachea to
introduce implants into the posterior junction of each successive
cartilage ring with the annular ligament, as described below.
[2654] However, the avoidance of withdrawal and reentry in the
airway is not onerous as it is in the bloodstream, and such a
capability is often unnecessary. The single barrel radial discharge
barrel-assembly and not the simple pipe is recommended when space
is lacking to insert and withdraw the simple pipe without risk of
injury to the larynx. In smaller patients, a simple pipe
barrel-assembly may be usable for a distance towards the bronchi,
down to which the diameter of the lumen becomes so restrictive that
it becomes necessary to withdraw and replace the simple pipe with a
single barrel radial discharge barrel-assembly. The bounce-plate is
thus incorporated into a second simple pipe rather than as an
option that would be opened or closed in a single embodiment.
[2655] Under such circumstances, withdrawal and reentry is
preferable or essential, so that a single embodiment capable of
discharge both distad and proximad, which to provide entails
additional complexity and cost greater than the sum for separate
barrel-assemblies where one does and the other does not have a
bounce-plate, is not preferred. Accordingly, a simple pipe
barrel-assembly that reverses the direction of the trajectory is
provided in a separate barrel-assembly. FIGS. 32 and 34 show a
simple pipe barrel-assembly with a manually attached bounce-plate
at the distal end of the muzzle-head. An attachable bounce-plate is
not deployable or retractable with the muzzle-head intracorporeal
and is suitable only for occasional or isolated use for directional
reversal of the trajectory when laryngeal clearance to admit the
tip with bounce-plate is adequate.
[2656] Bounce-plates that allow insertion through the larynx then
extension of the bounce-plate into position during use and
retraction before withdrawal are described below in this section
and shown in FIGS. 35 thru 37. Except for the addition of
bounce-plate 53 and a soft protective annulus 52 adapted for the
change in configuration of the muzzle-head that results from the
bounce-plate, the simple pipe is the same as that shown in FIG. 31
with only a soft rubbery protective ring 52 surrounding the tip.
Since the front portion of a full circle protective annulus 52
interferes with mounting bounce-plate 53, a hybrid annulus
consisting of a soft or rubbery portion at the rear and
bounce-plate portion at the front provided.
[2657] The bounce-plate portion may consist of bare metal or metal
with an outer rubbery coat, which is then preferably unitary with
the rubbery rear portion. A detailed view of the tractive
electromagnet 46 mounted in the concavity on the underside of the
simple pipe barrel-assembly in the curve 45 approaching its distal
end is shown in FIGS. 31 thru 34. The loss of a miniball in the
airway being unlikely and posing little risk even were it to occur,
an antemagnet chamber as seen in magnet assemblies used in radial
discharge barrel-assemblies for use in the bloodstream described
below, is not used. In FIG. 33, recovery electromagnet 46 is
enclosed within electromagnet housing 56 made of any hard
plasticizer free resin and bonded in position by means of an
adhesive that is pliable after curing as discussed in the preceding
section.
[2658] When the airway is large enough that withdrawal of a
muzzle-head without bounce-plate as shown in FIGS. 31 and 33 and
reentry with a rebound muzzle-head or muzzle-head having a
bounce-plate, such as those shown in FIGS. 32 and 34 poses minimal
risk of injury, the separate embodiments are used. When the airway
is not so small as to necessitate the use of a radial-discharge
barrel-assembly, a simple pipe with a bounce-plate is used. The
bounce-plate is a distal tip cap (crown, ferrule) friction-secured
fitting that to attach or replace necessitates removal and
reintroduction of the pipe; a bounce-plate that is endoluminally
deployable and retractable addressed in the next section, and one
that is endoluminally adjustable in angle addressed in the section
following that.
[2659] If, for example, the simple pipe is polypropylene on the
outside and the nonferrous metal of the bounce-plate is an alloy of
aluminum, the adhesive, which must remain pliant after cured, is
preferably a two part polyurethane, such as Loctite U-05FL,
mentioned above in the preceding section entitled Simple Pipe
Barrel-assembly. The angle of rebound equal and opposite to the
angle at which the miniball strikes the bounce-plate upon exiting
the original muzzle-port, seen in FIG. 34 as 55, the angle
described between the trajectory upon colliding and rebound off of
the bounce-plate is usually 45 degrees.
[2660] Rebound dissipates the kinetic energy and momentum or
propulsive force imparted to the miniball necessitating adjustment
of the airgun setting. Since the simple pipe barrel-assembly is
intended for use in the trachea and the single-barrel radial
discharge barrel-assembly for use in the tracheobronchial tree when
the lumen diameter is confining, sections to follow the description
of these single barrel barrel-assemblies will be directed to the
application of these barrel-assemblies for use in the airway.
Multiple discharge barrel-assemblies, which are not used in the
airway but rather in vessels and ducts are described later.
[2661] The simplest type of rebound deflection plate, shown in
FIGS. 32 and 34 consists of an angled tip that is slipped over the
distal end of a pipe such as that shown in FIGS. 31 and 33 after
pulling off the rubbery ring intended to protect surrounding tissue
in the larynx and surrounding the lumen from gouging. Once
introduced, it is not retractable and therefore suitable when
insertion is unlikely to be repeated. The type shown in FIG. 36 is
deployable and retractable, and that shown in FIG. 37 rotatable as
well to adjust the radial angle of discharge more finely than is
readily accomplished by rotating the muzzle-head as a whole while
the muzzle-head is intracorporeal (inside the body).
[2662] VII2b(1)(a). Intracorporeally Nondeployable Nor Adjustable
Bounce-Plate Attachment
[2663] A bounce-plate attachment is suitable where a need for
repeated adjustment once inside the body as would require
withdrawal and reentry and thus increasing the risk for injury to
the larynx, for example, can be discounted. When it cannot be
discounted, an embodiment which can be adjusted without the need to
withdraw, descrbied in the sections to follow, is used. The portion
of muzzle-head 45 in FIG. 34 corresponds to the terminal segment in
FIG. 33, shown with elastomeric protective annulus 52. The
intracorporeally nonadjustable bounce-plate attachment shown in
FIG. 34 is slipped over the end of muzzle-head 45 after elastomeric
protective annulus or guard 52 has been removed.
[2664] Adjustment to the elevation angle of the attachment is by
forcibly bending its recurved distal end with bounce-plate 53. The
angle of the the slip on deflection plate causes the trajectory 54
to be directed proximad. A shape holding sleeve of copper,
aluminum, or plastic can similarly serve this purpose in a simple
pipe without a bounce-plate. If a plastic pipe is used at all, the
preferability of a straight length of a more pliant tubing with the
use of a bendable slip-over sheath is clear. The curve imparting
sleeve can be temporary or bonded to the end of the muzzle-head by
means of an adhesive. An intracorporeally nondeployable
bounce-plate is an attachment for changing the angle of discharge
as prefixed when slipped over the distal tip of the muzzle-head
after the protective elastomeric annulus has been pulled off.
[2665] Where the intracorporeally adjustable embodiments described
below are adjustable in bounce-plate angle of rebound elevation and
rotation or azimuth without the need for withdrawal, to accomplish
this with an attachment requires withdrawal, replacement of the
attachment with another having the correct conformation or
carefully bending the attachment to the exact conformation needed,
and then reintroducing the muzzle-head through the airway. Since
the exactitude of midprocedural adjustments in rebound angle that
might be applied manually is limited and necessitates withdrawal,
only occasional use for relatively simple procedures is
indicated.
[2666] Since in order to remove the direction-reversing attachment,
the muzzle-head must be withdrawn from the body, an
intracorporeally nonadjustable bounce-plate is substantially
limited to situations where the need for directional reversal alone
is recognized prior to entry. Whereas an endoluminally deployable
and retractable device imparts adaptability to unforeseen
circumstances, a simple attachment that must be slipped over the
distal end of the muzzle-head does not. For this reason, it is
essentially limited to situations where only directional reversal
at a fixed angle is needed. In contrast, intracorporeally
adjustable bounce-plates eliminate the risk of injury in traversing
the larynx repeatedly.
[2667] VII2b(1)(b). Intracorporeally Controllable Bounce-Plates
[2668] Enabling the operator to deploy and adjust a bounce-plate
from outside the body without the need to withdraw and reintroduce
the barrel-assembly every time it is necessary to make a routine
adjustment reduces the risk of injury, the duration of the
procedure, and therewith, the time the patient must be kept under
general anesthesia. Routine adjustments include reversing the
direction of implant discharge or the elevation or azimuthal angle
of directional reversal. The intracorporeally controllable
bounce-plate mechanism shown in FIG. 36 is less expensive to
produce but limited to less demanding procedures where trajectory
reversal can be obtained with less speed, convenience, and accuracy
than would be afforded by the embodiment shown in FIG. 37. With any
bounce-plate or rebound mechanism, control includes deployment and
adjustment in the angles of rebound rotation (azimuth) and
elevation.
[2669] Control in two dimensions with rotation at a rotary joint
situated behind or proximal to the bounce-plate mechanism allows
rebound to be directed to any point within the band subtended in
enfilade; however, adjustment in elevation is not sufficiently fine
to allow precise readjustments between aiming points to be made
quickly. Finer adjustment in elevation is obtained at less cost
than would incorporating a supplementary fine adjustment by forming
the bounce-plate with a curved contour so that use of the
bounce-plate mechanism rotation control to effect small changes in
the vertical inclination or attitude of the bounce-plate
proportionally shifts the orbit described for a given angle of
elevation by rotating the muzzle-head about the rotary joint.
[2670] Referring now to FIGS. 33, 36, and 37, rotating the
barrel-assembly as a whole or the muzzle-head 45 at rotary joint
133 seen in FIG. 33 situated proximal to the bounce-plate
mechanisms shown in FIGS. 36 and 37 with bounce-plate 53 set at a
fixed angle of elevation causes successive miniballs to enter into
the surrounding lumen wall along a circle or circumference which
represents the outer edge of the lower portion of a cone described
by the successively discharged miniballs where bounce-plate
strike-point as point of origin describes is rotated about a circle
at a level beneath the cone apex or vertex. In a simple pipe as
opposed to a radial discharge barrel-assembly where the barrel-tube
or tubes would become twisted, rotary joint 133 allows muzzle-head
45 to be rotated in a complete circle repeatedly.
[2671] If the major axis of the muzzle-head is in or coaxial with
the longitudinal axis of the lumen, then the outer edge of this
cone will be circular, or describe the base of a right angle cone.
If the muzzle-head is abaxial (off axis), then the edge of the cone
will be off-circular or describe the base of an oblique cone, the
miniballs directed toward the more distant wall of the lumen
entering at a greater distance from the point of rebound origin. In
FIG. 36, push-pull control rod and in FIG. 37, push-pull control
tube 135 is fastened to control slide block 134 by journalling in
the inner rotatable ring of bearing 136, of which the outer ring is
securely fastened to block 137.
[2672] Rotation and horizontal reciprocation control lever 138 is
retracted proximally to (behind) control slidebox 134 when
bounce-plate 53 is not deployed, but moves forward into flush
position against the rear of control slidebox 134 when bounce-plate
53 is deployed. Apposition thus brings control lever 138 into flush
relation with the rotational calibration or scale inscribed along
the upper surface or ledge of calibraton or scale plate 143 applied
to the rear of control slide-box 134, allowing control tube 135 to
be rotated. Rotation allows rebound to be moved about an imaginary
cone with apex or vertex at the strike-point. Grinding or otherwise
forming the striking face of bounce-plate 53 so that it curves to
either side of the central strike-point allows deviation from the
orbital aiming point.
[2673] The extent of horizontal displacement forward or backward of
bounce-plate 53 is shown by a calibration or scale engraved along
the upper back ledge of slidebox rotation calibration 143 just in
front of control lever 138. For use in structured lumina, a fine
fiberoptic endoscope (angioscope, flexible boroscope) is clipped
alongside the barrel-assembly to provide a clear view of the aiming
point in any event. When the distal end of the bounce-plate is not
clearly seen, a second scope is provided for the purpose. This and
the fact that an elastomeric cap can cover the distal end of the
bounce-plate minimize the risk of injury during bounce-plate
deployment (ejection, unstowing) and use.
[2674] A bounce-plate which can be controlled from outside the body
can be rotated independently of, and so long as it does not press
against the lumen wall, without regard to, the position of the
muzzle-head as a whole. In FIG. 36, division of control rod 135
sheath into proximal control slide-box 134 and distal controlled
slide-box 140 allows bounce-plate 53 to be retracted into the
unensheathed segment expediting its replacement, maintenance, or
exceptionally, a need for midprocedural cleaning Bounce-plate 53 in
the more costly embodiment of FIG. 37 provides the open segment not
for the replacement or maintenance but rather to expedite
midprocedural cleaning of permanent bounce-plate 53 should it
become fouled with mucus, for example.
[2675] Where this eventuality is predicted, the need to withdraw
and reenter is averted through the addition of a fine aspiration
line clipped to run adjacent to the angioscope alongside
muzzle-head 45 for the midprocedural clearing of debris. Rotation
or azimuthal adjustment of the bounce-plate when it is fixed in
angle of elevation will cause the miniballs to enter the lumen wall
in an arc within the cone base described or outlined when the
muzzle-head is rotated as a whole. More specifically, independent
rotation of the bounce-plate occurs at a point along the circle
described when the muzzle-head is rotated. The bounce-plate
strike-point is the same whether rotated concentrically to the
muzzle-head or about its own long axis.
[2676] Therefore, the movement of both the strike-point on the
bounce-plate and the aiming points of rebound stand in epicyclic
relation where rotating the bounce-plate draws the trajectory
inward in relation to the circle of discharges. Rotation of the
bounce-plate when flat-faced thus allows small local deviations
from the larger arc obtained through overall rotation in the sense
of allowing the larger circle to be drawn inward from the circular
base or orbit and in this way enable fine and quick control over
the limited arc for a specific point along the orbit when the
muzzle-head is not rotated. The face of bounce-plate 53 can also be
formed or ground to alter the rebound angle, thereby allowing the
operator to deviate from the major orbit or `cone base` more finely
and quickly by rotating the bounce-plate than by adjusting the
angle of elevation, and to do so without the need to adjust the
angle of elevation for the orbit as a whole.
[2677] To eliminate an additional degree of freedom that would
allow the bounce-plate 53 to be rotated about its vertical as well
as its horizontal axis, the strike-face when spring steel is formed
and when solid stock ground with a concavity of whereby the rate
and extent of curvature determine to what distance the miniball
trajectories can be diverted inward. The rebound trajectory can be
diverted sideways or inside the major orbit set by the elevation
according to the angle at which the miniball strikes bounce-plate
53, and may be increased by widening the bounce-plate. This
displacement can be applied for individual discharges, or the
setting of the rotational angle of bounce-plate 53 can be applied
to the entire orbit to draw it inward.
[2678] With two levels of rotational freedom and a third
contributed by the ability to rotate the bounce-plate, any
rotational angle of the muzzle-head is readily attained: If
nonrotatably mounted to the airgun muzzle at the twist-to-lock
connector, then rotary joint 133 in FIGS. 31 thru 33 is used. If
connected to an airgun mounted to a linear positioning stage on a
swivel carriage as shown in FIG. 83, then a second point for
rotation is available. The intracorporeally controllable
bounce-plate mechanisms described in the following sections provide
an additional adjustment for the rotational angle of rebound.
Similarly, with an air pistol, the barrel-assembly is rotated as a
whole or at joint 133. When rotated midprocedurally, the `top` or
`upper surface` of a barrel-assembly is that of the muzzle-head,
not that of the bounce-plate or the vertical axis.
[2679] Whether along a longer muzzle-head, the junction between
barrel-catheter and muzzle-head, or at a level along the
barrel-catheter, rotary joint 133 must be positioned sufficiently
proximal along the barrel-assembly that it remains extracorporeal
and accessible for manual adjustment. Since the bounce-plate
mechanism must be continuous and its push-pull handle and rotation
lever or arm 138 shown in FIGS. 35 thru 37 must also remain
accessible, rotary joint 133 must be positioned proximal to the
proximal end of the bounce-plate mechanism. Control slide-box or
sheath 134 is ordinarily extended up to controlled slide-box or
sleeve 140. Controlled slide-box 140 is advantageously identical to
distinct bounce-plate 53 housing when bounce-plate 53 is of a shape
that would result in added expense were it unitary or continuous
with the bounce-plate mechanism proximal to it.
[2680] However, the primary requirement to avoid protrusion
severely limits the outer dimensions of such a controlled sleeve,
as well as necessitates withdrawal of the barrel-assembly to change
the bounce-plate. Whether control rod 135 and bounce-plate 53 are
ensheathed continuously or with a distinct controlled slide-box
140, the paired control and controlled slides move forwards and
backwards together. Thus, pushing control lever 138 and control rod
135 forward advances and deploys, or unstows, bounce-plate 53. As
shown in FIG. 35, an intracorporeally deployable and rotatable
bounce-plate mechanism is mounted at the top of the simple pipe
barrel-assembly, a less costly embodiment shown in FIG. 36 and a
precision embodiment in FIG. 37. Both FIGS. 36 and 37 represent
push-pull handle and rotation control lever 138 and slide-block 137
as moved to the most forward (distal) position.
[2681] FIG. 36 shows nonmagnetic spring stainlees bounce-plate or
tongue 53 retracted into control channel 145, while FIG. 37 shows
solid nonmagnetic stainless steel slab bounce-plate 53 fully
ejected in correspondence to the forward position of control lever
138. Whereas the embodiment shown in FIG. 36 passively adjusts the
rebound angle of elevation in proportion to the extent that control
rod 135 is advanced and bounce-plate 53 is ejected as a dependent
variable, that shown in FIG. 37 provides an additional degree of
control independent of the displacement of control tube 135, which
must be fully advanced before control lever 138 can be used to
adjust the angle of elevation of bounce-plate 53.
[2682] Another advantage in the embodiment shown in FIG. 37 is that
bounce-plate 53 need not be changed midprocedurally to adjust for
significant changes in the momentum of discharge to achieve
penetration to a greater depth, into harder tissue, and/or because
the mass of the miniballs is significantly changed with changes in
composition. Since stenting miniballs can be coated with
medication, significant changes in mass among miniballs should
arise very seldom, especially in the veterinary applications for
which a less costly bounce-plate mechanism is desirable for use
with a less costly air pistol. A formation that intersperses
stenting and drug delivering miniballs, for example, is usually
avoidable but would necessitate bounce-plate replacement.
[2683] By contrast, the less costly embodiment shown in FIG. 36
requires that control rod 135 with spring stainless steel
bounce-plate or tongue 53 be withdrawn through friction fitted
rotary bearing 136 in order to exchange bounce-plate 53 with
another that differs in its preformation or resilience whether due
to materials, thickness, or both. No resistance posed to
bounce-plate 53 during ejection, so long as it is springy, the
preformation imparted to bounce-plate 53 in manufacture and not its
resilience determines its decompression characteristics during
ejection and conformation when fully ejected. Withdrawing push-pull
handle and rotation control lever 138 as shown in either figure
would expose control and rotation rod or tube 135.
[2684] Overlying the recovery electromagnet assembly shown in FIGS.
31 thru 33, the bounce-plate mechanism excludes magnetically
susceptible materials. As seen in FIG. 35, when the simple pipe
includes an intracorporeally controllable bounce-plate mechanism,
elastomeric protective annulus or guard 52, provided to prevent
scraping or gouging injury from the sharp edge of exit-hole 55
(seen without the mechanism in FIG. 33) extends entirely about to
encircle the distal end of the bounce-plate mechanism. Control
slide-box 134 contains slide-block 137 which journals push-pull and
rotation control rod 135 within proximal rotary bearing 136,
allowing control rod 135 to be rotated and slid forward and
backward within the limits set by the space enclosed within control
slide-box 134.
[2685] The lower cost of the embodiment shown in FIG. 36 is
obtained through the use of a solid rod 135 to gradually push
curved blade type bounce-plate 53 out of alignment sleeve or
controlled slide-box 140 at the distal end where the extent of
blade ejection passively sets the rebound angle of elevation
without a third degree of freedom in the form of a lever to
accurately adjust this angle. The calibration along the top of the
lower cost embodiment indicates the angle of rebound at that
position. The greater cost of the embodiment shown in FIG. 37
results primarily because control rod 135 is a hollow tube used to
convey a shaft with bevel gears at either end or a pulley to allow
bounce-plate 53 to be adjusted in elevation with precision and the
calibration associated with such control.
[2686] Elevation angle is thus not a passive consequence of the
exent of blade or bounce-plate 53 ejection but rather initiated
only once joint 141 is pushed past opening 142. Slide-block 137
interfaces with the internal surfaces of control slide-box
enclosure 134 to impart smooth travel with enough resistance to
allow control rod 135 to be accurately controlled with control
lever 138 while allowing control rod 135 to rotate within it. The
resistance should be slight enough that any obstruction to the
projection of bounce-plate 53 will immediately signal to the
operator the need to slightly retract, adjust, and readvance before
proceeding. Bounce-plate 53 in FIG. 36 may be used when partially
deployed; however, to prevent jamming, in the fully forward
position, bounce-plates 53 in both FIGS. 36 and 37 must extend
beyond exit-hole 55 to a distance greater than the diameter of a
miniball.
[2687] To prevent incisions, bounce-plate 53 is limited in length
to the diameter of exit-hole 55, and must not extend past the lower
edge of exit-hole 55. Control slide-box housing 134 can be
transparent or opaque and continuous along the top of muzzle-head
45 to distal end 55 of muzzle-head 45 or since both control
slide-box 134 and controlled slide-box 139 are fastened to the
upper surface of muzzle-head 45, left unenclosed, in which case
inert sleeve or controlled slide-box 140 toward the distal length
of the mechanism as shown in FIGS. 36 and 37 is provided to
constrain rod 135 to the correct position. Whether continuous or
interrupted and continued with slide-box 140 as shown, the sleeve
encircling control rod 135 is made of a low friction material such
as polytetrafluoroethylene.
[2688] The extent of deviation from the major orbit is deterimed by
the width and curvature of the bounce-plate. A separate distal
sleeve or controlled slide-box 140 is used when the conformation of
the bounce-plate makes manufacture simpler and quicker than
machining or otherwise forming a different shape at the distal
segment of a continuous bounce-plate control rod or tube sleeve.
When present, a separate distal sheath requires neither slide-block
nor rotary bearing.
[2689] As all other components of bounce-plate deployment and
adjustment mechanisms, push-pull and rotation control rod 135 in
FIG. 36 or tube 135 in FIG. 37, must be nonmagnetic, tortionally
noncompliant as not to distort helically when the operator uses
push-pull handle and rotation control lever 138 to adjust distal
bounce-plate 53 in rotary angle or azimuth, must not fatigue
fracture despite its small dimensions, or if a tube, its thin wall,
and is therefore made of a strong nonferrous metal, alloy thereof,
or a nonmagnetic stainless steel. When the material of control
slide-box housing 134 is not transparent to allow a reference
pointer at the top slide-block 137 to be seen as projected against
a calibration along either side in the upper surface of control
slide-box 134, pointer 139 projects up through and moves along a
slot in the top of control-box 134 to indicate the extent to which
control rod 135 is displaced forward, which is equal to the
distance that bounce-plate 53 projects beyond the distal end of
muzzle-head 45.
[2690] Similarly, the left edge of push-pull handle and rotation
control lever 138 moves past rotary indicator calibration plate 143
between it and the rear of proximal end of control slide-box 134 to
indicate the angle to which intracorporeal and unviewable
bounce-plate 53 is rotated. Control over the angle of elevation in
the first embodiment described below passive, push-pull handle and
rotation control lever 138 is used to adjust the rebound angle of
elevation by translation of control rod 135 forward or backward. By
comparison, control lever 138 in the combodiment with positive
control over elevation shown in FIG. 37 is pushed to rotate it
forward to depress, and pulled to rotate lever 138 backward to
raise, bounce-plate 53.
[2691] Accordingly, push-pull handle and rotation control lever 138
in FIG. 36 rotates only from side to side or along a imagninary
x-axis, while that in FIG. 37 also rotates in the forward and
backward or y-axis. Control over elevation in the embodiment of
FIG. 37 thus requires a stationary elevation calibration plate
mounted coaxially with the axle of control lever 138 which does not
rotate. Calibration plate 143 and those indicating the angle of
elevation fastened to either side of the of push-pull handle and
rotation control lever 138 in FIG. 37 (not shown) are press formed
with outer edge folded around to allow the calibration to continue
from the vertical to the horizontal or horizontally tending surface
for improved visibility.
[2692] Push-pull and rotation control rod 135 in the simpler
embodiment of FIG. 36 and the push-pull and rotation control tube
135 of precision embodiment of FIG. 37 are journaled within rotary
bearing 136 at the proximal end of control slide-block 137.
Rotating push-pull handle and rotation control lever 138 thus
allows push-pull and rotation control rod or tube 135 in the
embodiments of FIGS. 36 and 37 to be rotated while remaining
journaled within to move forward and backward with control
slide-block 137 within control slide-box 134, so that pushing it
forward advances, and pulling it out retracts control rod or tube
135.
[2693] In the less costly embodiment of FIG. 36, the angle of
rebound elevation is adjustable to the extent allowed by retraction
of curved bounce-plate 53 into terminal aligning sleeve 140. With
elevation adjusted by this means, pointer 139 and associated
calibration marked along the top of control slide-box 134 indicate
the elevation. In the embodiment of FIG. 37, the elevation is
adjusted with greater precision but only once joint 141 clears
exit-muzzle-head 45 exit-hole 55. The angle of elevation is then
adjusted with the calibration disks (not shown) fastened to either
side of push-pull handle and rotation control lever 138 axle
144.
[2694] VII2b(1)(b)(i). Intracorporeally Controllable Bounce-Plate
with Limited Adjustability in Elevation
[2695] Turning now to FIG. 36, shown is a simple bounce-plate
control mechanism which allows bounce-plate 53 to be deployed from
outside the body with limited adjustability and accuracy in the
rebound angle of elevation. Among suitable materials addressed
below, bounce-plate 53 can be a nonmagnetic stainless spring steel
tongue that is compressed or flatterned when retracted into or
stowed within controlled slide-box or distal sheath 140 by pulling
out control lever 138 and returned to its curved shape by intrinsic
restorative force or shape memory as decompressed upon being
ejected through front opening 142. The resilience and restorative
force of bounce-plate 53 is thus limited, and for that reason, it
will maintain consistency in the angle of a miniball rebound off
its surface only up to a certain strike momentum as determined by
the exit velocity (`muzzle velocity` of the miniball).
[2696] Compared to the embodiment shown in FIG. 37, omitting the
rebound angle of elevation as an axis or degree of freedom under
control eliminates the need for a control lever that toggles, or
rotates forward and backward, as well as side to side, the axle
joint required for movement thus, a pulley or shaft with bevel
gears at either end coursing through a control tube used to
transmit the motion, and a precision machined bounce-plate.
Specifically, in the less costly embodiment shown in FIG. 36,
withdrawing control lever 138 is calibrated along the top of
control slide-box 134 and adjusts the elevation angle of rebound as
it retracts bounce-plate 53 into its distal sleeve or controlled
slide-box 140. By comparison, in the embodiment described in the
section to follow, precise control in the elevation angle is by
calibration and operational only when lever 138 is fully forward
wherewith bounce-plate 53 is fully deployed.
[2697] In FIG. 36, bounce-plate 53 is preformed of a springy metal
and/or possibly strong plastic resin, usually a nonmagnetic spring
stainless steel, within the range of restorative force that allows
it to be retracted without such resistance as would cause
muzzle-head 45 to jerk while in use. Steels capable of meeting the
requirements are specified in the section above entitled
Intrinsically Magnetized Stent-jackets with sources for such
materials addressed below in the section entitled Independent and
Subordinated Control of a Stay Insertion Tool Auxiliary Syringe
Holding Frame. Intrinsic restorative force or springiness causes
bounce-plate 53 to passively unbend as it is ejected out through
controlled slide-box 140 front opening 142. According to the form
and restorative force of bounce-plate 53, this gradually changes
the effective elevation angle of rebound.
[2698] In To be noted is that the function of bounce-plate does not
commence only once the length ejected passes over the center of the
imaginary front tangent of a discharged miniball; lesser exposures
can `clip` the exiting miniball, sending it in a different
trajectory than in the long axis of the `muzzle.` Midprocedural
accuracy demands preprocedural testing and recording of the exact
settings used to achieve the trajectory desired. Different
curvatures, materials unitary or laminated, widths,and thicknesses,
hence, restorative forces can be imparted to bounce-plate 53. The
longitudinal axial length of interchangeable bounce-plates are the
same, subject to the constraint that the lower wall of muzzle-head
45 must not be overextended due to the risk of gouging injury.
[2699] Limitation in the overall length of the bounce-plate
disallows elongating it to incorporate different curves along
successive segments and therewith the adjustability in rebound
angle of elevation available with such means. Withdrawing the
barrel-assembly will allow the bounce-plate to be changed
midprocedurally. Interchangeable bounce-plates made to the same
length, the extension is shown on the calibraton provided on the
upper surface of control slide-box 134 (not shown), and the rebound
angles that correspond to these distances are shown in a table
provided with the bounce-plate. However, withdrawal and reentry is
best avoided, leaving such an embodiment adequate for simpler
procedures performed with a interventionally modified air pistol,
for example, as addressed below in the section entitled Simple
Airgun Modified to Allow Limited Application.
[2700] By contrast, the embodiment described in the section to
follow incorporates a separate control to allow a permanent or
built in bounce-plate to be adjusted in angle of elevation. This in
turn does away with any need to exchange one bounce-plate for
another, which may require withdrawing and reinserting the
muzzle-head. Changes in exit momentum of such magnitude as
necessitate changing bounce-plate 53 midprocedurally are
deterimined by the hardness of the tissue to be implanted. In the
trachea, this typically necessitates changing the bounce-plate
once, all points to be implanted at one exit velocity implanted
first and the other tissue second.
[2701] Interchangeable bounce-plates are made of nonmagnetic spring
stainless steel and differ in resilience and conformation according
to it preformation. Bounce-plate or tongue 53 can be used to shift
the angle of rebound from the major orbit by rotating it with
control lever 138 in proportion to its rate of curvature and width.
As indicated in the preceding section, if necessary, control rod
135 with bounce-plate 53 is withdrawn through friction fitted
rotary bearing 136 by pulling control lever 138 backward. The
control rod-bounce-plate combination is then exchanged for another
or bounce-plate 53 is disengaged from the distal end of control rod
135 and replaced with another bounce-plate. For this reason,
control rod 135 is made in a wider diameter as will allow
bounce-plate 53 to be withdrawn through its channel without the
need to withdraw the barrel-assembly as a whole.
[2702] When bounce-plate 53 will pass through the channel to the
outside, it is quickest to exchange the combined control lever 138,
control rod 135, and bounce-plate 53 for another such combination.
Alternatively, with the combination fully withdrawn, bounce-plate
53 is disconnected from conrol rod 135 by pushing axle pin 146
connecting it in pivoting relation to the end of control rod 135
out one side of spindle 147, and fixing the replacement
bounce-plate by reinserting axle pin 146. If necessary, controlled
slide-box 140 is exchanged for another that fits the replatement
bounce-plate. To minimize the risk of trauma, the bounce-plate
mechanism is kept as little protrusive in relation to the
muzzle-head as possible.
[2703] When deployed, bounce-plate 53 spans across muzzle-opening
55 of muzzle-head 45 at an incline to the vertical and is therefore
slightly longer than the bore (chase) or internal diameter of
muzzle-head exit-hole or opening 55 plus the thickness of the upper
wall muzzle-head 45. FIG. 36 shows bounce-plate control rod 135 in
the fully forward position, which fully ejects bounce-plate 53
through front opening 142; however, for drawing compactness,
bounce-plate 53 is shown retracted or stowed within controlled
slide-box or sleeve 140. Bounce-plate 53 is never so narrow that it
can be withdrawn through the control rod channel This means that
bounce-plate 53 cannot be retracted to the outside through the
control channel, but requires withdrawing the barrel-assembly.
[2704] While the distal segment of the control rod sheath might be
formed to enclose a bounce-plate of any dimensions, compared to the
use of a continuous sleeve, a separate distal segment sheath, or
controlled slide-box, simplifies manufacture as well as offers some
practical advantage for maintenance. A separate controlled
slide-box 140 requires that a bounce-plate too wide to pass through
the sheath be removed only by withdrawing the barrel-assembly from
the body as a whole. Control slide-box or sleeve 134 forward of
slide-block 137 and its front wall stop can be extended entirely to
the front end of bounce-plate mechanism 53 to present the
appearance of a continuous sheath from end to end where
bounce-plate 53 is withdrawn into the front end thereof.
[2705] Whether retracted into a distinct or continuous distal
segment, the elevation or protrusion of the bounce-plate mechanism
above the upper surface of muzzle-head 45 must not risk injury;
instead, an overall smaller caliber barrel-assembly is used.
Push-pull and rotation control rod 135 is joined at its proximal
end toward the bottom of control lever 138 by single hammer head
eye or dowel joint insertion and connected at its distal end to
bounce-plate 53 by tightened machine screw with lock or Belleville
disc ring spring washer, snap, or similar fastener 147. Continuing
the rod through the back side of lever 138 provides an in-line or
single vector push and pull grab for advancing and retracting
bounce-plate 53.
[2706] Unlike the permanent rotary joint 147 of the embodiment next
to be described, fastener 147 allows bounce-plate 53 to be
disconnected and exchanged for another of different curvature and
rebound characteristic. Exchanging a bounce-plate of one
conformation for one of another allows the rebound angles of
elevation obtained at different bounce-plate projections out front
opening 142 to be changed. To change bounce-plate 53
midprocedurally requires withdrawing the barrel-assembly. For this
reason, changing bounce-plates is preferred only for setting the
rebound characteristic before the procedure is begun or when
operating in a surgical field opened for another reason.
[2707] The embodiment next to be described allows sufficient
control over rebound angle that the bounce-plate is permanent, so
that adjustments can be made more quickly, conveniently, and
without the need to withdraw the barrel-assembly. Control rod 135,
of nonmagnetic stainless steel, nonferrous metal, or plastic such
as styrene, passes through the proximal wall of controlled
bounce-plate 53 sheath or slide-box 140 beyond which it is fastened
to bounce-plate 53. The rear portion of control slide-block 137
extends proximally or backwards as ledge 148, which mounts
projection or nub 139 into which is etched a reference line that
passes along and projects up through a slot in the upper surface of
control slide-box 134. The slot is marked off to either side with a
calibrated scale that indicates the extent of forward displacement
of bounce-plate 53.
[2708] The extent of forward displacement significant in a measured
way, control slide-block 137 must move smoothly and positively
without a detent along the entire throw within control slide-box
134. Bounce-plate 53 must have springiness and prompt `shape
memory` to the extent that when slid forward, the curved and/or
creased conformation imparted to it can be substantially flattened
when withdrawn into its distal controlled sleeve and return to its
unflattened form as it is ejected. Preserving a cross sectional
area small as possible expedites passing through the vocal cords
and reduces the size of a laparoscopic access portal, for example.
The flatter bounce-plate 53 compresses without deformation, the
less will its sleeve or control slide-box 140 protrude above
muzzle-head 45 and the smaller will be the cross sectional
area.
[2709] By the same token, a thin springy tongue is easily deflected
at higher exit velocities, which can result in the need to
introduce a proportional correction factor in the angle setting.
Suitable materials for tongue 53 are tin bronze SS 5428-7,
beryllium copper CuBe 250, nickel-chromium-cobalt alloy, such as
Special Metals Division, Precision Castparts Corporation
Nimonic.RTM. 90 or Inconel.RTM. 718, or a nonmagnetic stainless
spring steel (see, for example, Yamamoto, S. and Sato, K. 1981.
"Non-magnetic Stainless Steel," U.S. Pat. No. 4,246,047). Spring
blade or tongue-type bounce-plate 53 is checked prior to use and if
found to have become deformed, is replaced.
[2710] The fastener used to attach bounce-plate 53 to the end of
control rod 135 well secluded from the surrounding tissue, any
suitable fastener, such as a small thumb machine screw, clasp, or
latch should be usable without concern for injury. To prevent
injury to the lumen wall, the distal and side edges of controlled
or bounce-plate 53 are padded with a protective elastomer. When the
bottom or hypotenuse of the right triangle formed by the plane
perpendicular to the forward edge of the exit port (muzzle,
muzzle-head exit-hole) and the plane of the bounce-plate is longer
than the diameter of the miniball, the exit path will be clear.
When shorter than the diameter of the miniballs but the exit
velocity is high, the miniball will usually clear anyway. When
shorter than the diameter of the miniballs so that discharge would
be obstructed, the hypotenuse can be lengthened by cutting away a
small portion of the lower rim of the muzzle-head.
[2711] A simple-pipe type barrel-assembly of unchangeable
conformation fitted with an unexchangeable bounce-plate would limit
the ability to target any point, especially where the anatomy
affords inadequate space to maneuver. However, the ability to the
bend muzzle-head and attach different bounce-plates reduces such
limitation. Raising the bounce-plate to a higher elevation allows
directing miniballs over an arc of rebound angles in the forward
direction, and rotation of the bounce-plate allows nudging the
aiming point aside of the unrotated position, just as smaller
angles of elevation direct miniballs in the reverse direction where
rotation of the bounce-plate likewise allows reaching points aside
from the vertical axis. The points in the surrounding anatomy that
can be targeted is thus significantly greater than the conformation
of the muzzle-head alone would suggest.
[2712] VII2b(1)(b)(ii). Intracorporeally Controllable Bounce-Plate
with Precision Adjustment in Rebound Elevation and Rotation
[2713] Now to be described is a bounce-plate control mechanism that
allows the bounce-plate to be deployed and retracted with precise
adjustment in the rebound angle of elevation while the muzzle-head
remains intracorporeal with no need to replace the bounce-plate
midprocedurally. Such capability is advantageous when dealing with
different tissues in hardness, that present nonuniform hardness as
the result of disease, that present at different angles so that
fine adjustments are needed to achieve accurate implant placement.
To withdraw and reenter introduces unwanted delays, increases the
risk of injury or irritation, especially to the entry point, the
need for the operator to reorient, and extends the time the patient
must be kept under general anesthesia.
[2714] By comparison, use of the embodiment described in the
preceding section which provides only passive control over rebound
angle of elevation for structured anatomy might necessitate
withdrawal and reintroduction of the barrel-assembly repeatedly. To
provide positive control over the rebound angle of elevation and
not just the passive control provided by the spring tongue
bounce-plate embodiment described in the preceding section, the
push-pull and rotation control solid rod or shaft 135 in FIG. 36 is
replaced with stationary or nonreciprocating and rotation control
tube 135. In this embodiment, bounce-plate 53 is not positioned at
intermediate horizontal postions (displacements, levels) as is the
preceding embodiment shown in FIG. 36 but is either fully retracted
(stowed) or fully deployed.
[2715] Ejection and retraction of bounce-plate 53 is accomplished
inside control tube 135, which conveys a pulley belt between
control and controlled pulleys or a shaft that joins control and
controlled bevel gears at control lever 138 with controlled or
distal pulley wheel or bevel gear at 141. Accordingly, advancing
and withdrawing control tube 135 requires no calibration to measure
horizontal displacement but does require a pointer on control lever
138 that moves against a calibrated scale mounted to control
slide-box 134 to indicate the angle of elevation. Since with this
embodiment the elevation is adjusted nonpassively by positive
control only when bounce-plate 53 is deployed or fully forward,
lever 138 will always be in the fully forward position flush to the
rear of control slide-box 134. In this embodiment, when rotated
fully back, control lever 138 fully raises bounce-plate 53 or
deploys it when rotated all the way forward.
[2716] The calibration indicating the angle of elevation therefore
need not move with lever 138. By comparison, control lever 138 in
the embodiment shown in FIG. 36, where the angle of elevation is
adjusted as the passive consequence of the extent of bounce-plate
ejection or horizontal displacement, is not rotated forward and
backward but pulled backward or pushed forward in a linear path.
This embodiment therefore requires no projection 139 with a pointer
or reference line that moves alongside a horizontal displacement
calibration scale to either side as does that shown in FIG. 36.
Numerous kinematic arrangements will allow control lever 138 when
swung or rotated forward and backward to rotate the pulley wheel
and belt or the bevel gear inside control tube 135 in turn is
received into control lever 138 toward its lower end.
[2717] The pulley belt or shaft passes through control tube 135 to
rotate the complementary distal pulley wheel or bevel gear that
raises and lowers bounce-plate 53. That described here uses a
pulley and is compatible with FIG. 37. Axle 144 is passed through
one of two round diametrically opposed holes cut into the sides of
control tube 135 toward its proximal end. These holes are slightly
larger in diameter than the axle and allow the axle to rotate
freely. Before axle 144 is passed through the opposing hole, the
pulley wheel is slid over the axle to its center and the wheel set
screw tightened. Its major portion having been passed forward
through control tube 135, the proximal end of a pulley belt is
looped about pulley wheel 141, and the axle passed through the
opposite hole.
[2718] The ends of axle 144 now project through the openings in
either side of control tube 135. Control lever 138 has holes at its
lower sides for friction fitting receipt of the ends of axle 144.
This is accomplished by slightly pulling apart the sides of lever
138, inserting the proximal end of control tube 135 between the
sides of control lever 138, aligning the ends of the axle
projecting from the side-holes in the control tube to the
side-holes in the lever, and pressing the lever side holes onto the
ends of axle 144. The axle is now immovably fastened at either side
to the control lever, so that pushing lever 138 forward easily
rotates axle 144, the pulley wheel, and pulley belt, thereby
rotating controlled pulley wheel 141, lowering or depressing
bounce-plate 53, and the reverse. When assembled thus, axle 144
serves also to strengthen control lever 138.
[2719] Since control lever 138 can adjust the angle of elevation
only when bounce-plate 53 is fully deployed and therefore in the
fully forward position and the most forward position of the lever
is vertical when flush against the back of control slide-box 134,
the forward throw or arc for lowering bounce-plate 53 generally
commences at the bounce-plate fully raised position with lever 138
approximately horizontal. Control slide-block 134 incorporates a
detent to cue the operator to its position without the need to look
at the mechanism. The detent consists of a small protrusion or stud
at the bottom of slide-block 137 which seats with a distinct click
into complementary depressions along the floor of slide-box 134,
thereby confirming that bounce-plate 53 is fully retracted and
bounce-plate 53 completely ensheathed or fully deployed and
positioned for discharge, whereupon special care must be given to
avoid gouging surrounding tissue.
[2720] VII2b(2). Trap and Extraction Recovery Tractive
Electromagnets for the Recovery of Loose and Extraction of
Mispositioned Miniballs
[2721] A barrel-assembly of any kind must include means for both
recovering any miniballs that are loose or that have been
mispositioned upon implantation. To recover miniballs, the forward
or distal end of a barrel-assembly, whether simple pipe or radial
discharge, is equipped with an electromagnet assembly that consists
of one direct-current tractive electromagnets in simple pipes and
two in radial discharge barrel-assemblies, which are as large in
size as the dimensions of the muzzle-head will allow. The U- or
generally horseshoe-configured core with elongated bridge is made
of vanadium permador (vanadium permendur) or silicon iron steel,
and the winding in smaller gauge models of braided alumina-silica
or alumina-boria-silica fiber ceramic-insulated silver wire.
[2722] In large gauged models for use in the airway and gut where
the need for recovery is less urgent, the winding is copper.
Whether disposed perpendically or parallel to the long axis of the
barrel-assembly, miniball recovery electromagnets are polarized and
trap-chambers or antechambers situated as shown in FIGS. 48 and 49.
To improve the ability to select one miniball among others, the
pulling pole is drawn to a needle point. For generating a field to
trap loose miniballs, the electromagnets are controlled as a pair
rather than independently.
[2723] Reversing the polarity of either exerts little practical
effect, a miniball never remaining positioned exactly at a point
where the fields theoretically null or cancel; instead, one or the
other field will always dominate at the points described by the
miniball, which will always be seized by that electromagnet.
Continuously varying the amperage to the elecromagnets allows
varying the magnetic field strength and magnetomotive force from
zero to the maximum. An optional laser catheter incorporated into
the barrel-assembly by positioning it along the longitudinal axis
to end at the center of the nose is without ferromagnetic content
and unaffected by the magnetic fields it traverses.
[2724] Metal-capping the front ends (tips) of the optical fibers
has been reported to yield better results (destruction or
atheromatous lesions with least injury to the lumen wall) than
bare-tipped fibers (Litvack, F., Grundfest, W. S., Papaioannou, T.,
Mohr, F. W., Jakubowski, A. T., and Forrester, J. S. 1988. "Role of
Laser and Thermal Ablation Devices in the Treatment of Vascular
Diseases," American Journal of Cardiology 61(14):81G-86G; Yang X M,
Manninen H, Soimakallio S. 1991. "Laser Ablation Ability of
Different Fiber Tips on Human Arteries. The Role of Photothermal
Effect," Chinese Medical Journal (English Edition) 104(9):721-727).
A metal tip or probe for the present purpose must be
nonferrous.
[2725] A means for trapping any loose miniballs must balance the
forward extendability toward a blind end or narrowing lumen
diameter to which the muzzle-head can procede with the need to
retrieve any errant miniballs to this depth. The diameter of the
muzzle-head varies according to the diameters of the lumens in
which each is to be used. For use in the coronary arteries, these
are on the order of 7-10 French. The tractive electromagnet in a
simple pipe barrel-assembly, seen as 46 in FIG. 33 is enclosed
within nonmagnetic housing 56 in FIGS. 31 thru 34, is singular,
whereas the tractive electromagnets in radial discharge
barrel-assemblies indicated in FIG. 39 and shown in FIGS. 48, 49,
65, 66, and 67 consist of a pair of individually controllable
electromagnets positioned so that their attracting poles look
outward to either side with polarities diameterically opposed.
[2726] Because the simple pipe is for use in the airway, wherein
the recovery of a radiopaque loose miniball does not pose a risk of
loss as in the bloodstream, providing the electromagnet with a
spring-loaded door and antemagnet chamber is considered
nonessential. The same basic magnet structure is used to trap any
loose or to extract any misplaced miniballs, whether the
barrel-assembly is of the simple pipe type with one electromagnet
or a radial discharge type with two. The dimensions and maximum
tractive force of the electromagnets is proportional to the
respective barrel-assembly. The use of electromagnets allows
adjusting the field strength to a steady or resting level to
recover loose miniballs, raise the current and thus the field
strength to extract implanted miniballs, then lower the field
strength to zero and so prevent the dislodging of well placed
miniballs as the barrel-assembly moves past these upon
withdrawal.
[2727] Miniballs used in the airway or gastrointestinal tract are
larger than those used in the vascular tree, for example, and
individually discharged. The failure of a miniball to implant or to
implant properly is thus noticed immediately, and since the patient
is recumbent, a loose miniball will fall and adhere to the tacky
lumen floor rather than drop into a lung. Accordingly, the recovery
electromagnet can be left off or set to a steady protective trap or
subextraction field strength, then raised to extraction field
strength if needed. The fact that the barrel-assembly usually has
an endoscope lashed alongside it, is equipped with a recovery
electromagnet or electromagnets, and can readily be connected to an
aspiration pump means that a mispositioned miniball is easily
retrieved.
[2728] Discharge into the vascular system, however, is always
performed with the tractive electromagnets set to a protective trap
field strength to prevent a loose miniball from passing downstream.
The resting field strength of the tractive electromagnets normally
sweeps up any loose or lost miniball. However, where such an
exigency would pose inordinate risk, the ability to locate a loose
or lost miniball is increased by using miniballs coated with
tantalum for increased radiopacity. In radial discharge
barrel-assemblies, the electromagnet assembly, indicated as to
relative position in FIG. 38 as 64 and shown as 80 in FIGS. 39 and
64 in FIG. 40, are mounted within chambers in a housing at the
distal or forward end of the muzzle-head. To allow tantalum coated
miniballs trapped in the magnet antechambers to be observed
flouoroscopically, magnet housing is preferably made of a
transparent material, such as polycarbonate.
[2729] Seen head-on in FIG. 40, the magnet assembly, indicated in
FIGS. 38 and 40 as 64 and in FIG. 39 as 80, constitutes the most
anterior or distal portion in any muzzle-head without, and the
second most anterior portion in any muzzle-head with a heat-window
in the nose, and is divided into two compartments, seen as upper
and lower in FIG. 40. The horseshoe-configured single working face
tractive electromagnets are contralaterally offset to allow a space
in front of each which is enclosed behind corner plastic-hinged
center-opening double doors that are recessed from the lumen wall,
are stopped by opening further by contact with the magnets to the
sides of the poles, and urged into closed position by means of
plastic torsion springs at the hinges.
[2730] Small tabs prevent the torsion springs from opening the
doors outwards or away from the magnet past the position to close
the magnet antechambers. The force with which a loose or
mispositioned miniball is drawn toward the magnet exceeds the
restorative force of the torsion springs that otherwise urge the
double doors into a closed position against the stop tabs. The
strength of the magnetic field and restorative force of the torsion
spring are sufficient to pull the miniball through and close the
doors regardless of the entry into the antemagnet chamber of mucus,
saliva, or blood. Recessing the double doors reduces the chance
that these will be opened by brushing up against or scraping the
lumen wall.
[2731] Since the attraction of a miniball already under recovery
forces the double doors open, to provide a sensor to sound an alarm
at the door hinge or spring is considered moot. As the front
portion of the muzzle-head and barrel-assembly, all external angles
of the magnet assembly are ground and polished smooth so that the
front end, i.e., the distal nose or face, is completely convex or
rounded, smooth, and continuous. Two of the blood-grooves that run
longitudinally midway between the muzzle-ports are aligned to the
spaces in front of each double door, and ground and polished so
that the groove continues into the space smoothly. The other two
blood-grooves are continued over the outside of the magnet
assembly.
[2732] The muzzle-head, to include the motorized turret collar,
port portion, and magnet assembly, is preferably encapsulated
within a lubricious coating, such as those specified above in the
preceding section entitled Sectional Extraluminal Stents, Segmented
and Articulated or Chain-stents. The pistol grip or dedicated
airgun controller thus has knobs to separately adjust the
potentiometers that control the exit velocity and two others to
adjust the field strength of the recovery electromagnets. Each
magnet in the pair or magnet set is separately controllable over
their range of magnetic field strength. For this reason, the same
electromagnet set can be used with a low or resting field strength
to catch any loose miniballs or to extract miniballs that have
already been implanted but misplaced.
[2733] To extract a miniball that has already been implanted, one
of the electromagnets is aligned alongside the misplaced miniball
and the amperage raised until the miniball is pulled to the magnet.
Increasing the amperage gradually to only the electromagnet
positioned and directed toward the specific miniball to be
extracted, the effect on other miniballs is minimized. The range of
propulsive force available with any airgun and the immediate
interchageability of different kinds of rotary magazine clips makes
it possible to place a different number of barrel-tubes, each of
variable diameter, within a barrel-catheter of given diameter for
use in the same airgun.
[2734] Up to a certain limit in the diameters of the miniballs
required, the barrel-catheter may be of a given size, which if
exceeded, will require the use of an airgun of larger bore or the
removal of a smaller and replacement with a larger diameter airgun
barrel lining. With an airgun of maximum bore, airgun barrel lining
adaptors and the ability to change the kind of rotary magazine clip
in a moment allow connection to any barrel-assembly. In such a
universal airgun, because the diameter of the airgun muzzle does
not change but only different bore-reducing or increasing linings
are inserted, the flange connector is of standard size such that
any barrel-assembly can be connected to the same airgun.
Accordingly, mechanical connection of the simple pipe
barrel-assembly to the airgun is preferably the same as that to be
described for single and multiple barrel radial discharge
barrel-assemblies.
[2735] By removing one kind of rotary magazine clip and inserting
another, the airgun can be quickly converted for use with
barrel-assemblies having from one to four or more barrel-tubes that
are alike. Different bores require changing the airgun barrel
lining. Regardless of the number or diameter of the barrel-tubes,
the barrel-assembly must always be precisely aligned so that each
barrel-tube is positioned before its respective hole in the rotary
magazine clip. The need to replace an airgun due to a malfunction
should not necessitate the withdrawal of a barrel-assembly already
placed within the lumen. To this end, interchangeability of a given
barrel-assembly into different airguns is of distinct benefit.
Reciprocally, when the diameter of the airway becomes too small for
a simple pipe, to switch to a single barrel radial discharge
barrel-assembly should not necessitate changing the airgun that is
already adjusted to the proper setting.
[2736] Apart from these advantages in uniformity of connection, the
expense to the practitioner is reduced. Barrel-assemblies should be
interchageably connectable to an airgun regardless of whether the
airgun has been modified from one sold on the market or was
originally made for interventional use. The interchangeability of
airguns and barrel-assemblies allows one and the same airgun to
support any number of different barrel-assemblies, which is
advantageous whether only one kind and size of barrel-assembly is
used, other airguns being usable in the event of a malfunction, or
barrel-assemblies of several different kinds and sizes are used,
where each airgun can be equipped with a different bore reducing
barrel lining
[2737] Accordingly, a single flange-connector size according to the
largest bore is preferred, a second airgun of still larger bore
reserved for large zoo mammal veterinary use. The rotary flange or
twist-to-lock connector limits the distance to which the
barrel-assembly can be inserted into the barrel of the airgun. This
places the end-plate before the rotary magazine clip with the least
interval separating the proximal ends of the barrel-tubes and the
hole in the rotary magazine clip respective of each
barrel-tube.
[2738] VII2c. Application of Simple Pipe-Type Barrel-Assembly to
the Magnetic Correction of Tracheal and Bronchial Collapse
(Veterinary)
[2739] Suspension of the collapsed tracheal ceiling (dorsal
membrane, dorsal ligament) is accomplished by placing miniballs or
stays alongside the membrane for retraction by small but powerful
permanent magnets. Depending upon the distribution of collapse and
condition of the patient, the magnets are held in place by a
segmental stent-jacket placed about the trachea itself, a
clasp-jacket placed about the esophagus, infixion in the form of
miniballs or stays in the floor or ventrum of the esophagus,
subcutaneous patch magnets anchored in the fascia overlying the
skeletal muscles of the back (posterior), or in a removable wrap
(harness, halter) placed about the neck and/or withers, singly or
in combination.
[2740] As addressed below, a clasp-jacket about or magnetic
implants in the floor of the esophagus, a segmented stent-jacket,
or subcutaneous patch-magnets can be used to suspend the tracheal
ceiling. The extrapulmonary (primary) bronchi can be jacketed, but
the intrapulmonary (secondary) bronchi must be patch-magnet
suspended. In the airway embodiment, a simple pipe or single barrel
(monobarrel) barrel-assembly as addressed below in the sections
entitled Simple Pipe Type Barrel-assemblies and Limited purpose
Single Barrel (Monobarrel) Radial Discharge Barrel-assembly, can be
used to implant miniballs adjacent to collapsed cartilage rings
along the dorsal tracheal membrane, or trachealis muscle.
[2741] Collapse of the tracheal ceiling is most often presented by
toy breed dogs at mid-life see, for example, (Ettinger, S. J. and
Feldman, E. C. 1995. Textbook of Veterinary Internal Medicine,
Philadelphia, Pa.: W. B. Saunders), but is also seen in several
other species, even adults, to include horses (see, for example,
Ohnesorge, B., Gehlen, H., and Deegen, E. 2002. "Disorders of the
Trachea in Horses," in Equine Respiratory Diseases, Ithaca, N.Y.:
International Veterinary Information Service; Couetil, L. L.,
Gallatin, L. L., Blevins, W., and Khadra, I. 2004. "Treatment of
Tracheal Collapse with an Intraluminal Stent in a Miniature Horse,"
Journal of the American Veterinary Medical Association 225(11):
1701-1702, 1727-1732), and goats (Belli, C. B., Benesi, F. J.,
Leal, M. L., and Nichi, M. 2003. "Trachael Collapse in an Adult
Goat," Canadian Veterinary Journal 44(10):835-836).
[2742] Donkeys may have deformed tracheal cartilages (Powell, R.
J., Du Toit, N., Burden, F. A. and Dixon, P. M. 2010.
"Morphological Study of Tracheal Shape in Donkeys with and without
Tracheal Obstruction," Equine Veterinary Journal 42(2): 136-141),
and calves may acquire tracheal collapse due to dystocic trauma
(Rings, D. M. 1995. "Tracheal Collapse," Veterinary Clinics of
North America. Food Animal Practice 11(1):171-175; Fingland, R. B.,
Rings, D. M., and Vestweber, J. G. 1990. "The Etiology and Surgical
Management of Tracheal Collapse in Calves," Veterinary Surgery
19(5)371-379). Provided the cartilages are sufficiently pliant and
pulmonary complications are not involved, the stenting described
herein will prevent asphyxia. By contrast, the tracheomalacia
encountered in human neonates is almost always due to immature
development with consequent lack of resilience, or chondromalacia,
in the cartilage rings by the time of birth, which spontaneously
resolves.
[2743] Ring resilience usually attained at 18-24 months (see, for
example, Bluestone, C. D. 2005. "Humans are Born Too Soon: Impact
on Pediatric Otolaryngology," International Journal of Pediatric
Otorhinolaryngology 69(1):1-8), unless severe (McNamara, V. M. and
Crabbe, D. C. G. 2004. "Tracheomalacia," Paediatric Respiratory
Reviews 5(2):147-154), unless suffocating, the treatment of
tracheomalacia in neonates is avoided. When severe and segmented
(localized) in neonates the use of a stent or stents to treat
tracheomalacia is generally discounted in favor of
bronchoscopically guided aortopexy (see, for example, Abdel-Rahman,
U., Simon, A., Ahrens, P., Heller, K., Moritz, A., and Fieguth, H.
G. 2007. "Aortopexy in Infants and Children--Long-term Follow-up in
Twenty Patients," World Journal of Surgery 31(11):2255-2259; Dave,
S. and Currie, B. G. 2006. "The Role of Aortopexy in Severe
Tracheomalacia," Journal of Pediatric Surgery 41(3):533-537).
Collapse pertaining to the tracheal ceiling or dorsum, and the
aorta posteriad, aortopexy is inapplicable in dogs.
[2744] No claim herein addresses a bioabsorbable extraluminal stent
for tracheomalacia as described by Hartig, G. K., Connor, N. P.,
Nalwa, S. S., and Sewall, G. K. 2003. "Bioabsorbable Exoluminal
Stent," United States Patent Application 20030028255. Stents are
used to treat the condition only when necessary (see, for example,
Anton-Pacheco, J. L., Cabezali, D., Tejedor, R., Lopez, M., Luna,
C., Comas, J. V., and de Miguel, E. 2008. "The Role of Airway
Stenting in Pediatric Tracheobronchial Obstruction." European
Journal of Cardiothoracic Surgery 33(6): 1069-1075).
[2745] Sabre sheath or sabre tooth trachea in an adult with
associated tracheomalacotic collapse the result of chronic
obstructive pulmonary disease is likewise stentable, but due to the
potential for development of erosive consequences, warrants
periodic reexamination (de Trey, L. A., Dudley, J., Ismail-Koch,
H., Durward, A., Bellsham-Revell, H., and 4 others 2016. "Treatment
of Severe Tracheobronchomalacia: Ten-year Experience,"
International Journal of Pediatric Otorhinolaryngology 83:57-62;
Peri , I., Paladin, I., Lozo Vukovac, E., Vela Ljubi , J., Gudelj,
I., and Lozo, M. 2015. "Tracheomalatia, to Stent or Not to Stent,"
Respiratory Medicine Case Reports 16:137-139; Choudhary, C.,
Bandyopadhyay, D., Salman, R., Gildea, T., and Mehta, A. 2013.
"Broncho-vascular Fistulas from Self-expanding Metallic Stents: A
Retrospective Case Review," Annals of Thoracic Medicine
8(2):116-120; Ranu, H. and Madden, B. P. 2009. "Endobronchial
Stenting in the Management of Large Airway Pathology," Postgraduate
Medical Journal 85(1010):682-687; Chin, C. S., Litle, V., Yun, J.,
Weiser, T., and Swanson, S. J. 2008. "Airway Stents," Annals of
Thoracic Surgery 85(2):5792-5796; Saito, Y. and Imamura, H. 2005.
"Airway Stenting," Surgery Today 35(4):265-270; Madden, B. P.,
Loke, T. K., and Sheth, A. C. 2006. "Do Expandable Metallic Airway
Stents Have a Role in the Management of Patients with Benign
Tracheobronchial Disease?," Annals of Thoracic Surgery
82(1):274-278; Fukai, I., Yamakawa, Y., Kiriyama, M., Kaji, M.,
Yano, M., Sasaki, H., and Fujii, Y. 2003. "Saber-sheath Malacic
Trachea Remodeled and Fixed into a Normal Shape by Long-term
Placement and then Removal of Gianturco Wire Stent," Annals of
Thoracic Surgery 76(2):597-598; Wood, D. E. 2001. "Airway
Stenting," Chest Surgery Clinics of North America 11(4):841-860),
as may be certain cases of tracheopathia osteoplastica and other
causes of airway stenosis (see Loo, D. K. and Allen, R.,
"Tracheopathia Osteoplastica Treated with Tracheal Stenting, Chest
126 Supplement:9658).
[2746] Remedy for some malformities and deformities without
conventional stenting as such is under development (see, for
example, Gao, M., Zhang, H., Dong, W., Bai, J., Gao, B., and 9
others 2017. "Tissue-engineered Trachea from a 3D-printed Scaffold
Enhances Whole-segment Tracheal Repair," Scientific Reports
7(1):5246; Huang, L., Wang, L., He, J., Zhao, J., Zhong, D., and 7
others 2016. "Tracheal Suspension by Using 3-dimensional Printed
Personalized Scaffold in a Patient with Tracheomalacia," Journal of
Thoracic Disease 8(11):3323-3328).
[2747] While tracheal and bronchial stenosis in neonates, unlike
that in toy dogs, for example, almost always subsides without
treatment, thorascopic aortopexy is also the treatment of choice
for tracheomalacia in older children, where prematurity of the
cartilage rings at birth is not a factor (Durkin, E. T., Krawiec,
M. E., and Shaaban, A. F. 2007. "Thoracoscopic Aortopexy for
Primary Tracheomalacia in a 12-year-old," Journal of Pediatric
Surgery 42(7):E15-E17; Carden, K. A., Boiselle, P. M., Waltz, D.
A., and Ernst, A. 2005. "Tracheomalacia and Tracheobronchomalacia
in Children and Adults: An In-depth Review," Chest
127(3):984-1005). Other procedures for ameliorating tracheomalacia
are tracheopexy and esophagopexy addressed below in the section
entitled Subcutaneous, Suprapleural, and Other Organ-attachable
Clasp- or Patch-magnets.
[2748] Despite numerous complications, endoluminal stents have been
used to treat severe tracheomalacia in children (see, for example,
Anton-Pacheco, J. L., Cabezali, D., Tejedor, R., Lopez, M., Luna,
C., Comas, J. V., and de Miguel, E. 2008. "The Role of Airway
Stenting in Pediatric Tracheobronchial Obstruction," European
Journal of Cardiothoracic Surgery 33(6):1069-1075) and adults (see,
for example, Ernst, A., Majid, A., Feller-Kopman, D., Guerrero, J.,
Boiselle, P., and 6 others, 2007. "Airway Stabilization with
Silicone Stents for Treating Adult Tracheobronchomalacia: A
Prospective Observational Study," Chest 132(2):609-616) in whom the
condition may be associated with Morquio syndrome, Larsen syndrome,
relapsing polychondritis, chronic obstructive pulmonary disease,
intubation, goiter, goiter, vascular rings, and a number of other
causes.
[2749] Other causes of obstructed breathing in neonates such as
congenital tracheal stenosis, may recommend the combination of an
extraluminal stent and surgery (see, for example, Hasaniya, N., el
Zein, C. F., Mara, S., Barth, M. J., and Ilbawi, M. 2006.
"Alternative Approach to the Surgical Management of Congenital
Tracheal Stenosis," Annals of Thoracic Surgery 82(6):2305-2307). In
a dog, however, tracheal collapse results when cartilage
maintenance expressed as resilience begins to fail in middle age
only to grow progressively worse. Accordingly, in man, pending
spontaneous correction, the threat of suffocation in a severe case
may warrant the temporary placement of an intraluminal stent.
[2750] Except where tracheobronchial constriction or collapse is
permanent if not progressive, the procedure to be described for use
in the airway is intended for veterinary application. Because the
advancement of collapse is due primarily to increased ring
infirmity and secondarily to stretching of the dorsal membrane from
respiration that is made possible by and thus increases in
proportion to the primary degradation in cartilage resilience, and
because early intervention truncates stretching, an initial
response should seek not to respond to the extreme collapse to
which the condition would invariably progress were there no
intervention, but rather to the condition as it exists.
[2751] While no tracheobronchial stent is etiotropic, or goes to
the underlying etiology, but only nosotropic in alleviating an
occlusion due to collapse of the airway, supporting the
tracheheobroncial ceiling will intedict continued stretching of the
collapsing dorsal membrane that the tidal flow of respiration, or
constant push-pull action of breathing, would otherwise constantly
aggravate. This action considerably increases collapse, which is
primarily caused by a progressive loss of resilience in the
cartilage rings due to a genetic defect expressed as an inadquacy
of cartilage synthesis. Unless stopped, tracheal collapse
eventually leads to inflammation and infection. For this reason, to
persist in purely medical palliation with no mechanical
intervention while the patient becomes more debilitated, and
moreover, to then perform a radical procedure that may even include
a thoracotomy, represents poor management.
[2752] Barring protracted dysphagia, but not a cough that commonly
persists well after conventional procedures, annoyance exhibited by
the patient due to unfamiliar forces on the trachea if any must be
weighed against the risks of frequent suffocation leading to a loss
of consciousness and even death were no invasive procedure
performed. If not alleviated, residual symptoms are reduced in
severity with medication. A definite error in the treatment of
tracheal collapse is the detension in mechanical intervention and
continued dependency upon medication that lacks the efficacy to
terminate further progress of the condition. Surgery tends to be
detained until the condition is advanced and as a result, the
patient much impaired, and intervention with existing tracheal
stents is properly detained because the stent itself creates
complications by interfering with normal physiology at the lumen
surface.
[2753] The existing classification of tracheal collapse (Tangner,
C. H. and Hedlund, C. S. 1983. "Tracheal Surgery in the Dog--Part
II," 5:738-762, reprinted in Ford, R. B. (ed.), 1999. Head and Neck
Medicine and Surgery in Small Animal Practice, Yardley, Pa.:
Veterinary Learning Systems, pages 236-246) assigns Grade I to a
reduction in the lumen during respiration of 25 percent; Grade II
to 50 percent, Grade III to 75 percent, and Grade IV to the
substantial elimination of the lumen during respiration. In a dog
with Grade I or II tracheal collapse (see, for example, Fossum, T.
W. 2002. "Surgical Management of Tracheal Collapse". Proceedings of
the 27th World Congress of the World Small Animal Veterinary
Association,
http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2002&PID=2695;
Johnson, L. R. 2001. "Diagnosis and Management of Tracheal Collapse
in Dogs," Waltham Focus 11(2):3-8; Johnson, L. R. 2000. "Tracheal
Collapse. Diagnosis and Medical and Surgical Treatment," Veterinary
Clinics of North America. Small Animal Practice 30(6):1253-1266;
King, L. G. 2004. Textbook of Respiratory Disease in Dogs and Cats,
St. Louis, Mo.: Elservier/Saunders, page 354; Venker-van Haagen, A.
J. 2005. Ear, Nose, Throat, and Tracheobronchial Diseases in Dogs
and Cats, Hannover, Germany: Schluetersche), the sagging dorsal
membrane can be suspended by means of ferromagnetic implants
(miniballs) drawn by small neodymium permanent magnets, which
depending upon the segment to be treated, the specific anatomy, and
contextual medical condition, can be positioned with a stent-jacket
or patch-magnets placed subcutaneously on the outer investing layer
of the deep or muscle fascia overlying the implanted miniballs
and/or suprapleurally, i.e., upon the serous membrane overlying the
lungs.
[2754] At incipient grades of collapse, significant closure of the
airway as the result of a diagonal folding flat of the trachea when
the head is raised as revealed by fluroscopic observation is
unlikely, allowing an initial intervention that is minimal. The
object being to minimize the trauma of stenting the collapse, the
incision needed to feed through and subcutaneously place a
longitudinally elongated open magnet-wrap without hooks and loops
over the trachea or a flexible segmented stent-jacket, for example,
is smaller than that needed to place stays, even with a stay
insertion tool that incorporates side-tilting. For this reason,
unless a malacotic condition recommends the use of wide stays,
miniballs introduced from within the trachea are preferred.
[2755] If having already progressed to Grade III or IV collapse,
the slack is pulled away laterally between ferromagnetic miniball
implants in the ceiling of the trachea and magnets secured beneath
the esophagus by means of a magnet-wrap as shown in FIGS. 10 and
11. The very malacia that demands correction renders the tracheal
ceiling sufficiently compliant to move with the peristalsis of the
esophagus during deglutition (swallowing) and without interference
to the mucociliary function of the trachea. Since tautening the
dorsal membrane alleviates the constant stretching action of
breathing, it should seldom be necessary to retrieve the
subcutaneous or suprapleural clasp magnets by means of an
electromagnet and institute the second option.
[2756] However, such a conversion from the first option, directed
to less progressed or lower grade collapse and the second to more
progressed or higher grade collapse may be accomplished at a later
date. Both procedures, placing fascial magnets and esophageal
tacking, or magnetic esophageal tracheopexy, avert the acutely
traumatic but nevertheless recommended procedures taught in every
textbook of veterinary surgery at a time when the patient has
become impaired by secondary sequelae, commonly ventricular and
atrial enlargement and increased density of lung tissue, and is
least likely to survive open surgery that may sever a thyroid
artery or recurrent laryngeal nerve.
[2757] Expansion in the area treated at a later date is then made
subject to actual eventualities, allowing trauma and risk to be
minimized. Since an initial procedure can always be expanded upon
at a later date when progress in the condition need not be
presupposed, and an interval for recuperation is gained, the
concept of extension for prevention is set aside. Furthermore,
following any intervention, an interval should be allowed for the
patient to learn to adapt to the new condition. If certain
postures, such as raising the head past a certain angle, initiate
the characteristic `goose-honk` cough, then the patient is likely
to associate this posture and coughing, and learn to avoid the
posture. Unless movement is restricted unacceptably, or coughing on
drinking or eating do not subside over time, reintervention is
deferred.
[2758] Rather than to actually stent the structure it surrounds, a
surrounding jacket can mount magnets to exert patenting traction
upon miniballs implanted in an adjacent structure, notably by the
esophagus upon miniballs implanted along dorsolateral longitudinal
lines running along the ceiling of the collapsed trachea, for
example. When a structure is not merely to support magnets for
exerting force upon a neighboring structure but is itself to be
stented, except that the endogenous outer layer of the structure to
be stented lacks sufficient elasticity and strength to withstand
puncture or retention of the miniballs, as may be true, for
example, of diseased ductus and the normal esophagus, then
reinforcement with an artificial or prosthetic `adventitia` of the
required properties is necessary.
[2759] Such a clasp-wrap or alternative means for introducing
ferromagnetic implants in the wall of a ductus may be acted upon by
either a more local stent-jacket or a magnet-wrap supported by a
neighboring structure. However, a wall diseased as to retain little
shear or tensile strength will present no substance to `grab hold
of` and will simply separate intra- or inter-laminarly (tunically
delaminate) and collapse beneath the artificial adventitia. A
structure so lacking in strength should be replaced with a graft or
prosthesis. Placed outside the tubular structure, such a
wrap-surround must be tissue compatible but requires no
immunosuppressive drugs as would pertain to a homograft or
xenograft.
[2760] When the miniballs can be mounted to a clasp-wrap (miniball
wrap-surround) or alternative means for introducing ferromagnetic
implants in the wall of a ductus, the need for implantation is
eliminated and since lumen diameter need not be sufficient for
transluminal access, ductus smaller in diameter than those
implantable can be treated. However, to achieve continuous adhesion
over the outer surface of the ductus that resists the traction of
the magnets and yet complies with the intrinsic movement within the
walls of the ductus, much less avoids interfering with such action,
is elusive as not to eliminate the need for implantation
capability. Because all bodily tissue, even the enamel of the
teeth, is constantly replaced, long-term adhesion is a problem.
[2761] The use of a clasp-wrap is considered a relatively
short-term solution unsuited to use in younger patients with a long
life expectancy. Furthermore, the use of a wrap-surround, whether a
clasp-wrap or a magnet-wrap, is limited to structures that are
readily encircleable with few if any attachments that necessitate
extensive dissection, and preferably with no more than loose
surrounding fascia. The interposition of an artificial adventitia
precludes the use of medication on the inner surface of the outer
or magnet-mounting component or stent-jacket. However, the
medication is then applied to the inside of the reinforcing wrap in
contact with the structure.
[2762] Integration with the host tissue is not a desirable means
for obtaining the adhesion of such an artificial adventitia to the
outside of the ductus, because it requires an antecedent procedure,
necessitates some negligible surface preparation scoring injury to
the intrinsic adventitia of the ductus requiring time to heal, and
usually results in bonding of insufficient strength to resist
dislodgement by the tractive force exerted by the magnets over
time, making adhesion undependable over the long term. Moreover,
the need for treatment is usually urgent, making a procedure
completed in a single operation imperative. The methods described
herein are intended to avoid open surgery, some avoiding incision
entirely, but do nothing to preclude reversal and the application
of alternative treatment should results prove inadequate.
[2763] All of the procedures described herein for the repair of
tracheal collapse are practically reversible, and neither in
performance nor reversal nearly so traumatic or hazardous as are
the standard procedures. If notwithstanding the use of magnetic
field strength sufficient only to prevent the dorsal ligament from
dropping down into the tracheal lumen and contrast to avoid injury
to the vessels of the trachea and esophagus dysphagia or discomfort
continues for more than 15 days following the esophageal tacking
procedure or magnetic tracheopexy, then the miniball magnets are
retrieved from the tracheal ceiling and esophageal floor by means
of an electromagnet and intraluminal stents inserted in the trachea
and bronchi as necessary.
[2764] Once magnets have been implanted, imaging other than
magnetic resonance must be used, this technology now employed in
veterinary practice. Other procedures described herein as might be
applied to humans must consider that older technology heart pacing
circuitry may be disrupted by proximity to magnets. An extraluminal
stent, because it completely mantles about or surrounds and can
seal an artery is better able to prevent rupture with hemorrhage
than is an intraluminal stent having the form of an open mesh or
grid. With a nonmagnetic stent-jacket, this reduces the risk of
incipient aneurysmal rupture, whereas with a magnetic stent-jacket,
weakening of the luminal wall with relatively high density miniball
implantation is unlikely to result in a rupture.
[2765] Studies of the consequences of small puncture wounds to the
internal elastic lamina have so far been limited to those produced
by microsurgical needles and microelectrodes with no opportunity
for healing. By comparison, the longitudinal segmentation of
stent-jacket bar magnets or the use of specially made bar magnets
that differ from those positioned longitudinally except arcuate in
conformation to complement the outer contour of the ductus when
vertically mounted to the outer surface of the base-tube and
magnetized in the radial axis allows an extraluminal stent to
comply with tonic (angiotonic), pulsatile, and peristaltic changes
in gauge regardless of the anatomical tube treated or the length of
the stent.
[2766] In addition to a systemic platelet blockade in arteries or
anticoagulant in veins administered as a precaution in preparation
for a transluminal procedure, the thrombogenic propensity of
multiple if small (typically 0.2 to 0.4 millimeter) puncture wounds
through the intima is additionally countered by coating the
miniballs with the same or the same type of medication. The
platelet blockade, anticoagulant, and other medication, such as an
antibiotic, can be directly applied to the outside of otherwise
unmedicated miniballs having a textured surface for tissue
infiltration or to assist in the adhesion of a coating such as a
solid protein solder.
[2767] The uncoated implant is thus able to inbibe the liquid by
capillary action (capillarity, capillary motion, wicking), whereas
an existing coat can already contain or absorb the medication. In
either event, the addition of a platelet blockade or anticoagulant,
for example, to miniballs would involve nothing more than wetting
the miniballs in the rotary magazine clip with a small gauge eye
dropper on insertion in the airgun chamber. The additive must be
fully absorbed into the coating and not form a film or residue on
the interior of the barrel-tubes as could result in jamming.
Another reason that the additive should be fully absorbed is that
penetration through the intima and at least some part of the media
would wipe away or squeegee all but a small amount of the additive
at the center of the rear surface of each miniball.
[2768] VII2c(1). Treatment of Tracheal Collapse in the Cervical
Segments, i.e., Cephalad or Anterior to the Thoracic Inlet
[2769] Tracheal collapse in thehuman neonate is almost always due
to immaturity of the cartilages at the time of birth and
spontaneously corrects itself over a brief interval; procedures
delineated herein for the correction of tracheal collapse pertain
to the progressively deteriorating condition encountered in
veterinary practice. The treatment of tracheal collapse in anterior
segments where the trachea has not yet entered into the surrounding
mediastinal tissue can be accomplished in several ways, to include
the placement of a stent-jacket about the trachea with lifting of
the dorsal membrane or ligament by bilateral stays, a clasp-wrap,
or ballistic miniball implantation with a simple pipe-type
barrel-assembly to either side of the membrane, none of which
suspend the membrane by a stent-jacket, magnet-wrap, or ductus
intramural implants in the esophagus.
[2770] Clinical judgment should always veer toward the least
traumatic, least risk prone, and shortest anesthetization time in a
specific case. It is possible to place the clasp-jacket around, or
implant stays or miniballs in the trachea and draw these upward
with stent-jacket placed about the trachea or stent-jacket or
magnet-wrap placed about the esophagus. The peritracheal
stent-jacket can be of any type described in the section above
entitled Types of stent-jacket. The magnetic force use is the
minimum that serves to lift the membrane and the attracted and
attracting elements--stays, clasps, and magnets if the jacket is
extrinsically magnetized, are limited to the edges along the
membrane and in tissue strong enough to minimize the risk of
rupture.
[2771] Miniblls can be implanted in the trachea or esophagus by
means of a modified commercial air pistol as addressed below in the
section entitled Modification of Commercial Airguns, the cost of
the apparatus low. The standard procedure involves the suturing of
individual rings cut from high density polypropylene hypodermic
syringe casings (see, for example, Hobson, H. P. 1998.
"Trachea--Treatment of Tracheal Collapse: Ring Prosthesis
Technique," in Bojrab, M. J. Ellison, G. W., and Slocum, B. (eds.),
Current Techniques in Small Animal Surgery, Philadelphia, Pa.:
Williams and Wilkins, Chapter 22; Buback, J. L., Booth, H. W., and
Hobson, H. P. 1996. "Surgical Treatment of Tracheal Collapse in
Dogs: 90 Cases (1983-1993)," Journal of the American Veterinary
Medical Association 208(3):380-384; Tangner, C. H. and Hedlund, C.
S. 1996. "Tracheal Surgery in the Dog," in Ford, R. B. (ed.), Head
and Neck Medicine and Surgery in Small Animal Practice, (Reprints
of articles published in 1983), pages 231-246; Hobson, H. P. 1976.
"Total Ring Prosthesis for the Surgical Correction of a Collapsed
Trachea," Journal of the Americal Animal Hospital Association
12:822-828), or less commonly, the polyvinyl chloride drip chamber
of an intravenous administration set (Ayres, S. A. and Holmberg, D.
L. 1999. "Surgical Treatment of Tracheal Collapse Using Pliable
Total Ring Prostheses: Results in One Experimental and 4 Clinical
Cases," Canadian Veterinary Journal 40(11):787-791), about the
collapsed trachea to serve as prosthetic cartilage rings.
[2772] This necessitates access through open exposure, the entry
incision extending over the entire length of the dorsal membrane
treated, to which the patient already impaired by the condition
should not be subjected. In calves, removal of the prosthetic rings
is sometimes necessary and no less traumatic than is the procedure
to place these Fingland, R. B., Rings, D. M., and Vestweber, J. G.
1990. "The Etiology and Surgical Management of Tracheal Collapse in
Calves," Veterinary Surgery 19(5)371-379). In pronounced contrast
to the trauma of a thoracotomy, the insertion of a stent-jacket,
stent-jackets, or articulated stent-jacket is through the insertion
of one end of the stent-jacket through relatively small incision at
the level that defines either end of the stent-jacket.
[2773] This drastically reduces the trauma of placing prosthetic
rings (see, for example, Woo, H. M., Kim, M. J., Lee, S. G., Nam,
H. S., Kwak, H. H., Lee, J. S., Park, I. C., and Hyun, C. 2007.
"Intraluminal Tracheal Stent Fracture in a Yorkshire Terrier,"
Canadian Veterinary Journal 48(10):1063-1066). The stent-jacket is
held in position by its textured internal surface or gauze lining
in relation to the intrinsic surface protuberances of the tracheal
rings and by the magnetic attraction of ferrous implants just
within the outer fibrous layer of the trachea. To secure a
stent-jacket with end-ties may necessitate additional keyhole
incisions.
[2774] The possible sequelae of such a procedure include infection,
dysphagia, and stimulation of the cough reflex; however, these
should prove medically manageable. Averting the risk of asphyxia is
considered worth any discomfort due to magnetic attraction between
tissues or, when magnets have been inserted subcutaneously or
suprapleurally, in relation to metal objects in the environment,
which the patient will never be too weak to leave and become
conditioned to avoid. That any medical procedure must be tested
extensively and over a long period is considered superfluous. If
thought necessary to avert migration, the placement of suture is
through and in line with this incision.
[2775] Requiring the extension of the incision to allow for
suturing separate rings eliminated, insertion of the stent-jacket
and its fixation in position are through an incision that is a
small fraction of the length required for the conventional
procedure, materially reducing trauma and extending treatment to
patients too impaired to withstand the standard procedure.
Extension of treatment to the distal bronchi is preferably by
dorsolateral ballistic implantation into the bronchial ceiling with
an eccentric two-way radial discharge barrel-assembly with the
ceiling to be suspended by subcutaneously or suprapleurally
implanted magnets (patch-magnets, clasp-magnets).
[2776] Dependent upon a small absolute diameter of the trachea for
symptoms to appear, the patient suffering from tracheal collapse
will almost always be a small dog. Distad, the lumens of the
bronchi are likely to become reduced to no more than a few French.
Such a severe reduction in working space may necessitate dispensing
with a simple pipe and continuing with a one-way radial discharge
or monobarrel-assembly of the kind ordinarily used for vascular and
ureteric applications. Adaptability in the use of
barrel-assemblies, and airguns that support different
barrel-assemblies are significant cost reduction factors.
[2777] VII2c(1)(a). Use of a Magnet-Wrap About the Esophagus to
Treat Tracheal Collapse in a Small Dog, for Example
[2778] Where the esophagus and trachea course together in
dorsoventral relation, tracheal collapse can be treated by the
collapsed membrane (dorsal membrane; musculus trachealis; tracheal
muscle) to the underside of the esophagus (magnetic esophageal
tracheopexy). To suspend the dorsal membrane thus, a simple pipe
barrel-assembly is used to implant miniballs at the junctions of
the annular ligaments toward the dorsolateral edges of the
cartilage rings. A compliant and nonconstricting magnet-wrap placed
about the esophagus containing magnets at intervals along
ventrolateral longitudinal lines suspends the miniballs. The
esophageal magnets are not ballistically inserted magnetized
miniballs, because the esophageal periphery tends not to be
sufficiently hard and the otherwise unaffected esophagus should not
be involved much less traumatized at the risk of inducing
dysphagia.
[2779] If the testing means and method described below reveals that
the ceiling is too weak or malacotic (soft) to prevent the implants
from penetrating and perforating the tracheal ceiling, then the
procedure is stopped and an endotracheal stent is inserted. While
peristalsis moves the esophageal ventrum or floor vertically, which
could pull against the dorsal membrane in a corresponding
undulative wave, it moves the sides laterally, and this lateral
movement affects the distance between the attractants slightly at
most. If the tracheal implants are centered in relation to the
lateral excursion of the peristaltic wave, then there will be no
vertical displacement of the dorsal membrane, which is suspended as
a side slung carriage.
[2780] Magnets within a magnet-wrap at intervals along
ventrolateral longitudinal lines running beneath the esophagus are
advantageous over subcutaneously or suprapleurally placed magnets
in presenting a magnetic field much weaker and local to the
treatment site and therefore effectively isolated from metal
objects in the surroundings. The spherical contour of the implants
essential for ballistic insertion presents a relatively poor gap
for magnetic flux. When collapse has already extended to the
bronchi, the decision to use subcutaneous or suprapleural magnets
should be weighed against more conventional endobronchial stenting
and the need for the patient to become conditioned to avoiding
immediate contact with metal objects in the environment such as
kitchen appliances.
[2781] This nuisance must be weighed against the obstruence of an
endoluminal stent within the tiny secretory and macrophage-swept
lumen. Any slack in the dorsal membrane resulting from the
stretching caused by inspiration and expiration while the rings had
continued to lose resilience and the ceiling increasingly collapsed
is taken up and drawn out laterally between the dorsoventrally
interfacing implants, draped over the side of the trachea, and thus
clamped outside the lumen. As is true in other ductus, the use of a
clasp-wrap to position miniballs along ventrolateral longitudinal
lines along the esophagus is intended to avoid placing soft tissue
under compression and restraining the passage of peristaltic
contractive waves along the esophageal floor.
[2782] Whereas the trachea is active constantly, peristalsis
normally occurs in the esophagus only during deglutition, and is
substantially confined to its ventral or inferior (in man, anterior
or rostral) two thirds. The very malacotic condition of the rings
renders the tracheal ceiling sufficiently flaccid to comply with
the peristaltic movement of the esophagus to which it has been
suspended without interference to the mucociliary function of the
trachea. Because the longitudinal lines of tracheal miniball
implants are placed just within the outer fibrous sheath or
adventitia of the trachea and the miniballs in the clasp-wrap are
positioned along ventrolateral lines, esophageal peristalsis should
be unaffected following healing, and coughing no longer presages
eventual suffocation.
[2783] During deglutition, the peristaltic waves are impressed upon
the tracheal dorsum; however, breathing is never simultaneous with
deglutition and the very flaccidity of the collapsed trachea
affords motile compliance. Nevertheless, some peristaltic induced
coughing while eating is to be expected. If coughing is due to
`tickling` that triggers the cough reflex rather than to occlusion,
then it is disregarded as a nonthreatening annoyance. If associated
with residual occlusion, then ventrolateral implants can be placed
over the segment affected or an intraluminal stent that is much
shorter than would have been required were it the sole treatment is
inserted. Barring immediate flush contact with a metal appliance or
vehicle, the subcutaneous or suprapleural magnets are not so
powerful as to prove problematic with metal objects in the
surroundings.
[2784] The patient eventually becomes conditioned through
experience to avoid snuggling up against such objects. In
conditioning to avoid certain postures, acclimatization to new
sensation, and to allow healing, the procedures to be described for
the palliation of tracheal collapse, while reversible, should be
allowed to remain in place until failure is certain. Where, as in
the extremities, a vessel is embedded in tissue, some special
consideration or complication must discourage the use of a
conventional intraluminal stent to justify the use of a
stent-jacket peripherally. The miniballs in the clasp-wrap placed
about the esophagus are placed at the average anteroposterior
interval by which the rings are separated and the trachea is then
pulled slightly toward the anterior or posterior to align the
tracheal and esophageal implants.
[2785] Even though both esophageal and tracheal miniball implants
have been inserted through the mouth, the trachea has been restored
to patency without sigificantly reducing the cross-sectional area
to less than normal, coughing has been reduced, the threat of
suffocation and the morbidity of incision and sutures has been
eliminated, and once healed, esophageal function is not
significantly affected. To accomplish the same repair by the
conventional means of suturing prosthetic rings about the trachea
requires approach through a cervical incision of considerable
length, to place the sutures opposite to the incision is awkward
extending the duration of the procedure, and when collapse has
already progressed to extend into the bronchi, the lateral
thoracotomy needed is untenably traumatic for the patient, whom the
condition has long impaired.
[2786] Gross motility of the trachea in terms of overall bodily
movement is reduced in detail by suspension from the esophagus;
however, these normally move together. Most conditions of collapse
should be remediated by a running dorsolateral magnetic tacking of
miniballs implanted in the tracheal ceiling to a magnet-wrap about
the esophagus as mentioned above. To avoid further stretching or
ripping of the dorsal membrane, this is done through the annular
ligament toward the ends of the rings. The existing grade of the
condition, which is always progressive, should be projected to
increase and extend posteriad over time. Therefore, regardless of
the existing grade and distribution of collapse, treatment should
be extended beyond the area affected.
[2787] Collapse of given grade at a level where the trachea is
bent, especially when the convexity is directed to the posterior,
can be more serious than when the course of the trachea is
substantially vertical or the convexity anteriad. If more
pronounced, a posterior convexity may necessitate the placement for
a length along the bend maximum of implants along the edges of the
ventrolateral quadrant of the tracheal floor as seen in
cross-section, with subcutaneous magnets to draw these implants
ventrolaterally, and esophageal tacking along the edges of the
dorsolateral quadrant of the tracheal ceiling for the adjacent
segments.
[2788] In advanced cases where collapse is such that the trachea
becomes folded flat when the head is raised, combining the present
method with the placement of prosthetic rings still makes it
possible to considerably, perhaps critically, reduce the extent of
surgery. Unless uniform tacking of the tracheal ceiling to the
esophageal floor is insufficient, the use of subcutaneous magnets,
especially in the cervical area, should be avoided as annoying the
patient when the head is turned. Generally, following the tacking
of the dorsal membrane as described herein, an interval should be
allowed to see if the patient can simply learn to avoid aggravating
postures before taking any further steps.
[2789] Single barrel discharge as used in the airway does not
require the use of a rotary magazine clip which provides
multibarrel discharge. Instead, semiautomatic oaperation is
supported by a caliber-adapted spring-loaded or gravity fed
magazine clip as described below. An otherwise ordinary gas
operated pistol, or hand airgun, that has been adapted in caliber
or gauge and lowered in exit velocity to the required range can be
used. Next to a jointed stent-jacket immediately surrounding the
implanted trachea, which is always preferred, the closest structure
from which the collapsed dorsal membrane might be magnetically
suspended is the floor of the esophagus.
[2790] VII2c(1)(b). Use of a Simple Pipe Barrel-Assembly to Treat
Tracheal Collapse in a Small Dog, for Example
[2791] Any procedure that involves placing implants in the
esophagus or gut may result in the severing or injury of
interconnecting neurons or fibers of the Auerbach (myenteric) or
Meissner (submucosal) plexus; however, these have abundant
interconnections and regenerate or heal quickly. A magnetic
tracheopexy involves placing magnetic implants in the floor of the
esophagus to suspend implants placed in the roof of the trachea is
likely to induce dysphagia that should resolve by the second week
following the procedure. In animal studies, complete transection
and anastomosis of the gastroinstestinal tract was followed by
regeneration of the myenteric plexus and nervous function within 2
to 8 weeks (Tokui, K., Sakanaka, M., and Kimura, S. 1994.
"Progressive Reorganization of the Myenteric Plexus During One Year
Following Reanastomosis of the Ileum of the Guinea Pig," Cell and
Tissue Research 277(2):259-272; Solov'eva, I. A. and Atanasova, E.
1977. "Restoration of the Electrical Activity and Nervous Apparatus
Following Section of the Stomach Wall in Dogs, " (in Russian)
Fiziologicheskii Zhurnal SSSR [Soyuz Sovetskikh Sotsialisticheskikh
Respublik (Union of Soviet Socialist Republics) Imeni I. M.
Sechenova [Sechenov Journal of Physiology of the Soviet Union]
63(5):723-734 (abstract in English at
http://www.ncbi.nlm.nih.gov/pubmed/892079).
[2792] By comparison, ballistic implantation can do no more than
infrequent and exiguous damage; functional impairment if any should
be tolerable and dissipate within 4 weeks. While improbable, a
perforation in the esophagus or trachea may damage fibers of the
right or left branch of the recurrent laryngeal nerve inducing
laryngeal spasm and respiratory distress (Tangner, C. H. and
Hedlund, C. S. 1983. "Tracheal Surgery in the Dog--Part II,"
5:738-762, reprinted in Ford, R. B. (ed.), 1999. Head and Neck
Medicine and Surgery in Small Animal Practice, Yardley, Pa.:
Veterinary Learning Systems, pages 236-246). Proximal damage to
these branches can result in dysfunction of the upper esophageal
sphincter and critical aspiration on swallowng (Orringer, M. B.
"Tumors, Injuries, and Miscellaneous Conditions of the Esophagus, "
Chapter 19 in Greenfield, L. J. Mulholland, M., Oldham, K. T.
Zdenock, G. B., and Lellemoe, K. D. (eds.) 1997.
Surgery--Scientific Principles and Practice 2d ed., Philadelphia,
Pa.: Lippincott-Raven.
[2793] Procedure for the palliation of tracheal collapse in a small
dog:
[2794] 1. The patient--usually a toy breed dog--is evaluated
bronchoscopically and radiologically to confirm collapse as the
cause of the symptoms and to observe the extent or grade of
collapse as well as to determine the working diameter afforded by
the anatomy. If the patient is too small, then the procedure is
discontinued, and if justified by life expectancy and judged
medically competent to withstand open surgery, the standard
procedure to implant polypropylene prosthetic cartilage rings is
performed. If not, then one or more deformation-resistant
intraluminal stents are inserted. If not too small, the patient is
evaluated for the variant of the procedure described herein, the
medication to be used, and the dosages to apply.
[2795] 2. A narrow gauge or small diameter pediatric bronchoscope
is lashed to the barrel-catheter, care taken to avoid bending the
catheter, and the patient preoxygenated. To clear the visual field
for the operator, aspiration may have to be intermittent or
"tubeless," spontaneous respiration used as the smallness of the
airway dictates. Tiny patients may require percutaneous
transtracheal jet ventilation or a preliminary tracheotomy with or
without jet ventilation.
[2796] 3. The patient is anesthetized and positioned supine on a
cushion that allows the airway to be straightened with head
dorsiducted or retroflexed and mouth gagged open as not to
interfere with breathing or with mobility of the neck, which may
then be positioned as necessary during the procedure. An adjustable
stage or intervening platform with adjustable pitch for placement
on the operating table gives improved access.
[2797] 4. The bronchoscope is used to locate the cartilage rings
and the conducting tube to insert one shot each into the anterior
junction of each successive cartilage ring with the annular
ligament bilaterally along the imaginary lines that demarcate the
lateral edges of the dorsal quadrant of the trachea were it
circular. Such placement not only takes advantage of the histology,
but introduces prosthetic support at the normal intervals. To well
seat the shot in each junction, the lamina propria is undercut by
lightly pressing the 45 degree tip of the barrel-catheter flush
against the endotracheal lining at a distance of 1/4 inch anterior
to each cartilage before triggering the shot. If the one miniball
at each ring is suspected to sufficiently palliate the collapse and
only dorsolateral subcutaneous or esophageal miniball magnets are
to be used, then this concludes the endotracheal portion of the
procedure, which should proceed directly to either the placement of
the subcutaneous or esophageal magnets.
[2798] 5. If increased suspension is considered urgent enough and
worth the additional time and swelling in one procedure, then using
a reverse 45 degree rebound tip or bounce-plate, a second pass is
performed to insert one shot into the corresponding positions of
each posterior junction bilaterally. The presence of a magnetic
body inside the anterior and posterior junctions of each cartilage
ring with the annular ligament through which the magnetic lines of
force course lifts each ring under the pull of the magnets. The
object is to arrange that the magnetic lines of force course
through both shot implants of each ring to create a virtual bit,
sling, or cross-pin that passes beneath and lifts each ring. If
only dorsolateral subcutaneous disk or esophageal miniball magnets
are to be used, then this concludes the endotracheal portion of the
procedure, which should proceed directly to placement of either the
subcutaneous disk or esophageal miniball magnets. If the need for
double implants is not considered urgent, then a second set of
posterior junction miniballs can be added at a later date;
nonmagnetic, polarity will pose no problem.
[2799] 6. If the collapse folds flat when the patient raises its
head so that dorsal mending alone is predicted not to sufficiently
palliate the collapse, then gag but not the bronchoscope or
barrel-assembly left in place, the patient is now turned prone,
chin resting, head dorsiducted with nonbinding support that allows
the neck to be circumflexed. The same process is then used to
insert implants in the same pattern along the imaginary lines that
demarcate the lateral edges of the ventral quadrant of the trachea
were it circular. This concludes the endotracheal portion of the
procedure, which should proceed directly to the placement of the
magnets whether subcutaneous or esophageal. 7. If the esophageal
tacking method is intended and step 5 has been skipped, then gag
left in place, the patient is now turned prone, chin resting, head
dorsiducted with nonbinding support that allows the neck to be
circumflexed. A magnet-wrap is introduced through an incision of
minimal length as described above and placed about the esophagus so
that the magnets are situated along imaginary lines that demarcate
the lateral edges of the ventral quadrant of the esophagus.
Fluoroscopy is used to assist in aligning the tracheal miniballs
and esophageal miniball magnets in vertically interfacial
relation.
[2800] 8. If subcutaneous disk magnets are to be placed
dorsoventrally or both dorso- and ventrolaterally, then to optimize
the positioning, strength and size of each disk magnet placed
dorso- or ventrolaterally, each magnet is first pressed downward
into the muscle to the depth of the muscle fascia by a trained
assistant while the operator observes the effect on the miniballs
that have been implanted in the trachea. Since the disk magnets
will be fastened to the laterally stable fascia, the repulsion of
neighboring like poles is not felt and serves to isolate or render
noninteractive the parallel magnetic circuits formed with the
respective miniball implants; the coursing of the field from the
same pole of one magnet to the same pole of an adjacent magnet of
like orientation to produce a diagonal pulling force as resultant
is precluded.
[2801] 9. If neither a stent-jacket about the trachea or the use of
a magnet-wrap about the esophagus is wanted, magnets to suspend the
collapsed tracheal ceiling can be placed subcutaneously at an angle
to draw the ceiling upwards with minimal compression to the
esophageal ventrum. Fur that interferes with such preliminary
positioning is trimmed away. Trying different magnets, the minimum
pull required at each level is determined. Testing for different
degrees of neck flexion, the operator uses the bronchoscope to
observe which combination of smallest magnets urges the cartilage
rings sufficiently erect to clear the airway, and marks the magnet
to be placed in each position on the pelage and if necessary, on
pressure sensitive adhesive backed labels temporarily placed on
each magnet. Within the effective distance, raising the magnets
reduces the pull, reducing, not increasing, any upward pressure
upon the esophagus that would produce discomfort in swallowing. The
fur is shaved at the prospective locations of magnet insertion. In
the cervical region, use of the smallest magnets most dorsally
positioned will eliminate or minimize the force of clamping
sufficient to retain any dorsal membrane slack between the miniball
and magnet when the neck is flexed. The same procedure is used to
position ventrolateral magnets if needed.
[2802] 10. A longitudinal incision through the integument on either
side of the line of implants allows fastening the subcutaneous
magnets to the surface of the muscle fascia. The prongs at the top
or bottom are engaged and the fascia pinched so that the prongs at
the other end engage when released. The incision is closed with
surgically approved long-chain methacrylate cement and swabbed with
antiseptic ending the procedure.
[2803] 11. Routine recovery measures to include the administration
of a local anesthetic to the prong sites as alertness is regained,
oxygenation and the administration of anti-inflammatory medication
are administered. If, as is common, steroids are to be avoided,
then provided not otherwise contraindicated, postoperative swelling
is managed with an NSAID such as Voltaren.RTM. (Novartis diclofenac
sodium) or Cataflam.RTM. (Novartis diclofenac potassium) or a
proteolitic enzyme NSAID such as Danzen.RTM. (Takeda Chemical
Industries) in enterically coated tablet form or SerraZyme.RTM.
(Health Australasia Limited serrapeptase; serratia peptidase). The
administration of antibiotics is in accordance with routine. Once
implants containing ferromagnetic metal have been implanted,
magnetic resonance imaging must not be used when the implants must
not be heated.
[2804] As with the conventional procedure, some coughing may
persist for an interval or permanently, and here as well, a cough
suppressant is administered at least pending healing. Once healed
and any strange sensation subsides, coughing will likely be due to
an incomplete resolution of the collapse, usually by virtue of
omitting a collapsing segment. A followup procedure is considered
if and only if the condition warrants. Before proceeding to
conventional surgery or the introduction of an endotracheal stent
or stents, the far less traumatic use of suprafacial clasp-magnets,
a stent-jacket or stent-jackets, and esophageal tacking or magnetic
esophageal tracheopexy should be tried, preferably, in separate
procedures in that order.
[2805] If none of these proves effective and the patient is a poor
candidate for surgery, then the miniball implants, if capable of
spontaneous expulsion over time, are withdrawn with the aid of the
simple pipe or a separate magnet, or if expulsion is not a concern,
then simply left in place as bioinert, a magnet-wrap applied to the
esophagus withdrawn, and a self-expanding nitinol stent or stents
inserted (see Kim, J. Y., Han, H. J., Yun, H. Y., Lee, B., Jang, H.
Y., Eom, K. D., Park, H. M., and Jeong, S. W. 2008. "The safety and
Efficacy of A New Self-expandable Intratracheal Nitinol Stent for
the Tracheal Collapse in Dogs," Journal of Veterinary Science
9(1):91-93; Moritz, A., Schneider, M., Bauer, N. 2004. "Management
of Advanced Tracheal Collapse in Dogs Using Intraluminal
Self-expanding Biliary Wallstents," Journal of Veterinary Internal
Medicine 18(1):31-42; Gellasch, K. L., Da Costa Gomez, T.,
McAnulty, J. F, and Bjorling, D. E. 2002. "Use of Intraluminal
Nitinol Stents in the Treatment of Tracheal Collapse in a Dog,"
Journal of the American Veterinary Medical Association
221(12):1714, 1719-1723; Hwang, J. C., Song, H.-Y., Kang, S.-G.,
Suh, J.-H., Ko, G.-Y., Lee, D. H., Kim, T.-H., Jeong, Y.-K., and
Lee, J. H. 2001. "Covered Retrievable Tracheobronchial Hinged
Stent: An Experimental Study in Dogs," Journal of Vascular and
Interventional Radiology 12(12):1429-1436; and Sawada, S., Tanabe,
Y., Fujiwara, Y., Koyama, T., Tanigawa, N., Kobayashi, M., Katsube,
Y., and Nakamura, H. 1991. "Endotracheal Expandable Metallic Stent
Placement in Dogs," Acta Radiologica 32(1):79-80).
[2806] In so doing, the type of stent must be chosen carefully
(see, for example, Madden, B. P., Loke, T. K., and Sheth, A. C.
2006. "Do Expandable Metallic Airway Stents Have a Role in the
Management of Patients with Benign Tracheobronchial Disease?,"
Annals of Thoracic Surgery 81(2):274-278; Radlinsky, M. G., Fossum,
T. W., Walker, M. A., Aufdemorte, T. B., and Thompson, J. A. 1997.
"Evaluation of the Palmaz Stent in the Trachea and Mainstem Bronchi
of Normal Dogs," Veterinary Surgery 26(2):99-107; Fraga, J. C.,
Filler, R. M., Forte, V., Bahoric, A., and Smith, C. 1997.
"Experimental Trial of Balloon-expandable, Metallic Palmaz Stent in
the Trachea," Archives of Otolaryngology--Head and Neck Surgery
123(5):522-528). The insertion of an endoluminal stent should be
resorted to only following failure of the procedure described above
and demands frequent reexamination.
[2807] Surgery is preferred to the use of endotracheal stents,
primarily, because these can fail (see, for example, Gobel, G.,
Karaiskaki, N., Gerlinger, I., and Mann, W. J. 2007. "Tracheal
Ceramic Rings for Tracheomalacia: A Review after 17 Years,"
Laryngoscope 117(10):1741-1744; Mittleman et al. 2004; Woo, H. M.,
Kim, M. J., Lee, S. G., Nam, H. S., Kwak, H. H., Lee, J. S., Park,
I. C., and Hyun, C. 2007. "Intraluminal Tracheal Stent Fracture in
a Yorkshire Terrier," Canadian Veterinary Journal 48(10):1063-1066;
Ouellet, M., Dunn, M. E., Lussier, B., Chailleux, N., and Helie, P.
2006. "Noninvasive Correction of a Fractured Endoluminal Nitinol
Tracheal Stent in a Dog," Journal of the American Animal Hospital
Association 42(6):467-471), the final recourse is to perform the
prosthetic ring procedure.
[2808] Some prefer the use of a stent only for patients that are
poor candidates for surgery (see, for example, Mittleman et al.
2004, cited above). Extraluminal stents afford superior results to
endoluminal stents (Sewall, G. K., Warner, T., Connor, N. P., and
Hartig, G. K. 2003. "Comparison of Resorbable Poly-L-lactic
Acid-Polyglycolic Acid and Internal Palmaz stents for the Surgical
Correction of Severe Tracheomalacia," Annals of Otology, Rhinology,
and Laryngology 112(6):515-521, the form of stenting described in
this specification, however, directed to progressive disease
treated with nonabsorbable materials). An extraluminal stent cannot
fracture, and the exposure essential to place the device is much
smaller than that to place and suture plastic rings.
[2809] VII2c(2). Treatment of Tracheal Collapse in the Thoracic
Segments, i.e., Caudad, or Posterior, to the Thoracic Inlet
[2810] When suspension of the collapsed dorsal membrane is by
esophageal tacking rather than through the use of a stent-jacket,
once trachea and esophagus diverge, magnetic suspension is attained
through the subcutaneous placement of magnets overlying the
affected area. By contrast, a single stent-jacket may continue
distally to the bronchial bifurcation, proximal portions of the
bronchi as may be accessed without thoracotomy can be either
stent-jacketed or suspended by subcutaneous magnets, or all
portions of the bronchi can be supported by subcutaneous magnets.
An object of the procedure is precisely to eliminate the need for a
thoracotomy using a form of stent that is placed outside of the
airway and od not susceptible to accumulating or clogging with
mucus as to require reinspection, withdrawal, and replacement.
[2811] An evaluation of the procedure to be used must consider the
course of the trachea in different body positions and not just when
the patient stands or sits. When the trachea is recurved,
subcutaneous magnets placed ventrolaterally to pull nonmagnetized
or magnetized implants placed ventrolaterally in the anterior wall
of the cervical trachea may occasionally be necessary to increase
tracheal patency. Since this produces the annoyance of sudden
clamping with movement, it is best avoided. Posterior to the neck,
however, such use need not be discouraged.
[2812] The combination of methods, here the use of intraluminal
stents in the bronchi, should always be considered. The following
is limited to the repair of tracheal collapse without the need for
incision of any kind or, if subcutaneous magnets are used,
incisions that are very few, small, and shallow. The preferred
treatment as delineated above requires a small incision through the
integument along the bottom of the neck or cervical ventrum and
insertion of a jointed stent-jacket. The best treatment for a given
patient must rest with the clinical judgment of the
veterinarian.
[2813] VII2d. Ablation and Angioplasty-Incapable Radial Discharge
Barrel-Assemblies
[2814] A radial discharge barrel-assembly is intended for use in
small diameter lumina such as arteries, the ureters, and bronchi
where the wall of the lumen must not be gouged or incised. As seen
by comparing the simple pipe barrel-assemblies shown engaged within
an airgun in FIGS. 31 and 32 and with muzzle-head 45 in greater
detail in FIGS. 33 and 34 to the radial discharge barrel-assemblies
shown in FIGS. 38, 39, 48, and 49, a barrel-tube in a mono- or
multibarrel radial discharge barrel-assembly as described below is
equivalent to a simple pipe type barrel-assembly where an outer
protective shell or torpedo-shaped body seen as 70 in the radial
discharge monobarrel shown in FIG. 38 and as 73 in the radial
multibarrel shown in FIG. 39 has been provided to enclose and
surround the muzzle-port or ports.
[2815] Shell 70 or 73 assures smooth slippage through the lumen and
protects the lumen wall by its shape, and if necessary, release of
a lubricant through the barrel-tubes, a service-catheter fed down a
barrel-tube, or a radial projection unit ejection tool-insert. The
shell also serves to detain any miniball that due to striking a
calcium deposit or otherwise sclerotic point, for example, failes
to penetrate the lumen wall until it is seized by recovery
electromagnet 80 as depicted in FIGS. 39 and 65 in FIGS. 48, 49,65,
and 66. Caught within the interface between the lumen wall and the
outer surface of the shell, the miniball is held within the
depression it makes in the lumen wall and thus tends not to move as
the shell slides over it.
[2816] However, even when the loose miniball rolls as the shell
moves over it, the barrel-assembly can be withdrawn so as to
position the tractive electromagnets to recover the loose miniball
into a magnet antechamber. Except in the smallest patients, there
is sufficient space in the trachea and bronchi to rotate the tip of
a simple pipe type barrel-assembly. In dogs weighing less than
about 7 pounds, it may be necessary to use a single barrel radial
discharge barrel-assembly as described below in the section
entitled Limited purpose Single barrel (Monobarrel) Radial
Discharge Barrel-assembly. Essentially enclosing a simple pipe
within a torpedo shaped shell, a radial discharge muzzle-head
presents no sharp distal tip as necessitates sufficient space to
maneuver it in order to avoid injuring the lumen wall.
[2817] The cylindrical conformation of a radial discharge
muzzle-head allows its introduction into a lumen slightly smaller
in diameter than the muzzle-head itself without the risk of
stretching injury or the need for a angiotonic relaxant
(angiotensin counteractant, hypotensive agent). The outer surface
of the muzzle-head body is made lubricious to prevent clinging.
Setting aside featues of internal structure that can be used to
vary flexibility using the same tubing, such as centering devices
as addressed in the section below of like title, radial discharge
barrel-assemblies can be made of many different tubing extrusions
and coextrusions in any of numerous material and profiles to
combine any desired flexibiilty with a slippery surface.
[2818] One way to both chemically isolate an outer surface that is
potentially allergenic and impart slipperiness is to enclose the
entire barrel-assembly in polytetrafluoroethylene shrink wrap. In a
barrel-assembly that includes a turret-motor, a slit cut around the
rotary joint or junction of motor to the proximal (rear) portion of
the muzzle-head, which is fastened to the barrel-catheter, frees
the forward portion to rotate, and film that would cover portals,
such as muzzle ports, side-ports, and the tops of radial projection
units, must be cut away. When made of nonferrous metal, to minimize
adhesion to the lumen wall, the muzzle-head of any radial discharge
barrel-assembly is preferably coated with a fluropolymer such as
polytetrafluroethylene.
[2819] When used in a structured lumen, such as the airway of a dog
that is small enough to recommend avoiding the use of a simple
pipe, and it is desired to introduce the implants in the retrograde
direction (proximad, toward the operator), to avoid injury to the
larynx and lumen by any protruding part, a radial discharge
barrel-assembly can be used that is equipped with an endoluminal
bounce-plate control mechanism as described above in the sections
entitled Extracorporeally Deployable Bounce plate with Fixed
Rebound Angle and Extracorporeally Deployable Bounce plate with
Adjustable Rebound Angle. To minimize the risk of injury, the
distal or front corners and edges must be rounded.
[2820] Since it is limited to one radius or maximally eccentric and
relatively small in diameter, and thus less likely to exhibit
strong resistance to twisting when torqued, but still includes
tractive electromagnets, a radial discharge monobarrel benefits
most from a turret-motor. The ability to aim the tractive
electromagnets with facility allows the resting or steady-state
trap retraction field force to be reduced reducing the risk for
extracting a miniball that has been correctly implanted, and the
radial projection units, installed normal to the longitudinal axis
of the muzzle-head, can be used rotationally as well as during
transluminal movement. Any radial discharge barrel-assembly must be
usable in the vasculature and must therefore incorporate means for
preventing:
[2821] 1. The introduction of gas into the bloodstream during
discharge.
[2822] 2. Admitting an amount of blood into the muzzle-head
sufficient to affect either the exit velocity or the internal
equalization of pressure significantly, and
[2823] 3. Preventing the loss of a miniball implant that could be
carried downstream.
[2824] Accordingly, if the size of the patient or preliminary
fluoroscopic examination reveals that the airway or distal portions
thereof are too small in lumen diameter to manipulate a simple
pipe, then a single barrel radial discharge barrel-assembly is
used. Such a barrel-assembly is the same as one used in the
vascular tree. Owing to the small diameter of most vessels and the
eccentricity of most vascular lesions, the single barrel radial
discharge barrel-assembly, because it can be made to the smallest
diameter of any barrel-assembly, has the widest applicability,
multibarrel embodiments serving to reduce operative time.
[2825] Even though working in the airway does not impose the
demands for gas containment and nonsusceptibility to thrombose or
clog that necessitates the use of a radial discharge device as in
the bloodstream, lumen diameters that are too constraining to use a
simple pipe necessitate the use of a radial discharge muzzle-head.
Since the degree of anatomical differentiation in the airway
becomes less distad, this is not a problem; however, an occasional
dog with collapsed trachea will be so small that a simple pipe can
be used for no more than the proximal segments.
[2826] The single barrel radial discharge barrel-assembly is
similar to the simple pipe barrel-assembly in that the
barrel-catheter and barrel are one and the same. The minimum
diameter of the muzzle-head necessarily limited by the number of
barrels, the single barrel radial discharge barrel-assembly allows
access to vasculature and ductus very small in gauge, allowing
treatment more deeply or distal into the vascular or
tracheobronchial tree. Access to vessels and ducts less than a
millimeter in lumen diameter also extends applicability to neonates
and small veterinary patients. For this purpose, a rotary is more
versatile than a linear feed magazine clip in allowing successive
implants of different mass.
[2827] VII2d(1). Limited Purpose Single Barrel (Monobarrel) Radial
Discharge Barrel-Assembly
[2828] Extraordinary exceptions aside, neither limited purpose nor
minimally capable barrel-assemblies can function independently of
an interventional airgun. They differ in that a minimally capable
barrel-assembly, as shown in FIG. 38, although a radial discharge
monobarrel, is provided with a blood-groove along the side of the
muzzle-head indicating that it also incorporates a heating element
or laser in the nose for perfunctory preemptive or precautionary
angioplasty to reduce the risk of releasing debris from plaque
whether due to contact with the muzzle-head. More capable, it can
be used to do the work of the limited purpose type.
[2829] A limited purpose barrel-assembly also differs from a
multibarrel minimally capable type as shown in FIG. 39 in that it
incorporates a single barrel. It is intended for use with a
similarly inexpensive air pistol to alleviate tracheal collapse in
a veterinary specialty practice, several different procedures for
accomplishing this addressed herein, but also has uses in medical
practice outside the vascular tree. Essentially limited to use
outside the vascular tree when thermoablative capability is not
essential, in smaller gauges, it is suitable for use inside the
trachea of a dog too small to safely insert a simple pipe, or in a
ureter, or in the reproductive tract, while in larger gauges, it
can be used in the gastrointestinal tract.
[2830] VII2d(2). Multiple Radial Discharge Barrel-Assemblies with
One- to Four- or More-Way Radial Discharge Muzzle-Heads
[2831] Radial discharge barrel-assemblies for use in blood vessels
must include gas return channels, and since Barrel-assemblies which
can be used in a blood vessel can be used in any other kind of
ductus, the figures reflect configurations suited to the more
demanding application. Barrel-assemblies not suited for use in a
blood vessel must be clearly marked as such, and can be made more
simply and at less expense by omitting the gas return channels.
Unlike balloons, solid catheteric devices such as a rotary burr,
laser, or barrel-assembly cannot be deflated to allow resumption in
the flow of blood past the device. This factor imposes a severe
demand for miniaturization in the diametrical extension of the
parts within the barrel-assembly, hence, the number and caliber of
barrels.
[2832] The smaller the implants, the greater must be the
distribution density to achieve a uniformity of pulling force that
reduces to an acceptable level the risk of implants being gradually
pulled through the adventitia with or without a portion of the
subjacent layer or tunic leaving the lumen unaffected, for which
contingency, preventive means will be described. Balloon-based
deflatable or otherwise collapsible and re-extendible muzzle-heads
and muzzle-heads having collapsible and re-extendible chambers
would make possible the use of larger caliber implants, but would
introduce much additional structural, materials, and bonding
complexity where the embodiment would have to be fully
dependable.
[2833] More significantly, a collapsible embodiment would
unavoidably and unacceptably compromise the distal electromagnet
assembly essential to trap loose and extract improperly positioned
miniballs. For this reason, a deflatable or mechanical
linkage-based collapsible muzzle-head is discounted, flow past the
muzzle-head being achieved by keeping the muzzle-head diameter to a
minimum not simply for this part of the barrel-assembly as a whole,
but at each longitudinal level along its length and by providing
pathways in the form of external blood-grooves and
through-and-through tunnels that allow blood and contrast dye
essential to confirm the reinstatement of patency to pass.
[2834] Preferred are mono and multibarrel Barrel-assemblies which
are unitized components which include a proximal end-plate, the
barrel-catheter containing the barrel-tubes, a motorized turret if
present, and a muzzle-head which includes the proximal muzzle-ports
through which the projectiles or miniballs are expelled and a
distal tractive electromagnet set to recover any loose or misplaced
miniballs, and a forward hemispherical nose to minimize the risk of
perforations. For barrel-assemblies within a given range in
diameter, simple pipe or single barrel and multiple barrel radial
discharge embodiments are preferably engageable by the same airgun
when the suitable airgun bore-reducing lining is inserted. The use
of rotary magazine clips greatly facilitates the ability to change
the caliber and thus allow one airgun to support numerous
applications.
[2835] Muzzle-ports that face in opposite directions not only
accelerate the process of implanting ductus that unlike the airway,
lack structural differentiation, but inherently cancel the reaction
to miniball discharge or recoil associated with transit through a
curve to discharge when not counterbalanced. Turning now to FIG.
39, shown is a four-way or four barrel radial discharge
barrel-assembly consisting of a barrel-catheter 72, muzzle-head 73,
and four barrel-tubes 74 in FIGS. 39 and 41 of which only two are
shown in these middle longitudinal sections, and stop-and-lock ring
75, which engages a ring with complementary interlocking
projections on the muzzle of the airgun best seen in the detailed
views of FIGS. 73 thru 75. Muzzle-head 73 includes turret-motor 76,
and rotating muzzle spindle 77, which includes the tractive
electromagnet assembly 80 at its front or distal end.
[2836] Turret-motor housing 78 is bonded to the outside of
barrel-catheter 72 by clamping collar 81. When the barrel-catheter
is of a material and thickness that becomes too soft when heated to
90 degrees centrigrade by the turret-motor stator while used for
thermal angioplasty at during stall, clamping collar 59 is lined
with a thermal insulant, such as poyurethane. At 95 are centering
devices and at 96 a blood-tunnel, both described in sections that
immediately follow. Muzzle-head body 73 is preferably micromachined
in proximal (rear, turret-motor housing) and distal (front,
ejection-head) portions under computer numerical control from a
solid block of nonmagnetic stainless steel of material as specified
above and hardened by heating and quenching.
[2837] en made thus, each pair of barrel and pressure relief
channels, shown as 226 in FIGS. 48, 49, 65, and 66, are machine or
laser-drilled diagonally and radially toward the longitudinal axis
from the same aperture. Effectively a segment of the barrel, the
outer surface of the proximal portion of the electromagnet assembly
housing must be longitudinally aligned to the central arc of the
barrel-channel To prevent the gas pressure of discharge from
forcing gas into the bloodstream, paths of least resistance to the
flow of the pressurized gas are placed in communication with the
muzzle-ports to return the gas to the peribarrel space. The
cross-sectional area of the return path is equal to or larger than
the sum of the cross-sectional areas of the barrel-tubes.
[2838] When appearing narrower than this in cross-section, it is
because the barrel-channels are elliptical normal to the view.
Material that is thicker than needed for the strength to resist
deformation, fracture, and work hardening in normal use is avoided,
especially in the spindle portion of the muzzle-head distal to the
engagement of spindle neck 61 in FIG. 38 in the position of a shaft
through in the through-bore torque turret-motor rotor 82 and the
entry after distoradially diverging or splaying, that is, flaring
outward, of barrel-tubes 74 into flush joints 84. To counter
deformation of the barrel-tubes as would impede if not jam miniball
ejection during or following rotation of the muzzle-head, the
degree of rotation to either side is limited and the distal ends of
the barrel-tubes are not tightly fit or gripped about but free to
reciprocate.
[2839] As shown in FIGS. 39, 48, 49, 65, and 66, the abaxial or
concentric rotational relation of the barrel-tubes to the
barrel-catheter, which may be supported with centering devices,
allows barrel-tubes 74 to continue through turret motor rotor 60
and 82 and spindle 77 in alignment, then to diverge and insert into
the muzzle-exit holes with flush joint 84 that extend proximally
from the exit-holes to allow reciprocal movement of the distal ends
of barrel-tubes 74 when the muzzle-head is rotated provide at the
front of ejection head 112. As shown in the same drawing figures,
the proximal length of barrel-catheter 72, its contents, motor
housing 78, and turret-motor stator 83 are fixed together and
stationary.
[2840] That is, only spindle 77, consisting of flex-ring 111, and
distal metal portions, which are unitized by bonding with the
segment of the barrel-catheter journaled in rotor 82, rotate, the
barrel-tubes continuous through the bore of motor rotor 82 and
inserting at their distal ends into the ejection-head 84. Rotary
joint 79 divides barrel-catheter 72 between the proximal portion
clamped in clamp collar 81 fixing it in position and distal portion
journaled within motor rotor 82. The distal portion of the
barrel-catheter that is journaled in rotor 82 as the spindle stem
or neck is bonded to the proximal end of convoluted tubing or
elastic flex-ring 111. Clamp collar 81 fixed to the rear of
through-bore configured turret-motor 76 locks pre-rotary joint
proximal barrel-catheter 72 in coaxial relation with the distal
segment of the barrel-catheter journaled in rotor 82 for rotation
as the stem or neck of spindle 77.
[2841] For a four-way radial discharge muzzle-head, rotation is
limited to 22.5 degrees in either direction for discharge and 90
degrees for electromagnet assembly extractions of misplaced
miniballs. Muzzle-head detail FIG. 39 can also represent a two-way
radial discharge muzzle-head, except that for the rotation of the
barrel-tubes by 90 degrees, in either direction, the length, i.e.,
the recess and distance of reciprocation within flush joints must
be slightly longer and the barrel-tube material used more pliant
without deforming upon discharge. To prevent air from leaking out
of the gas return channel and thus allowing blood to enter the
muzzle-head, the barrel-assembly and airgun chamber must airtight
except through the barrel.
[2842] The polymer of the barrel-tubes, which may consist of many
different materials and compound tubing, must be sufficiently thick
and strong that jerking and deformation do not significantly affect
discharge. Preferably, there is little change in exit velocity as
the rotational displacement is varied. Upon entry into the muzzle
spindle 77, barrel-tubes 74 enter the splay-chamber, which allows
the barrel-tubes to bend while flared centrifugally and to maintain
the consistent association of each with its respective muzzle-port
88, situated about the periphery of the muzzle-head. Depending upon
eccentricity of the lesions to be treated, the muzzle-ports may be
equidistant or eccentric.
[2843] So that the barrel-tubes can counterdeformatively rotate and
reciprocate, or move up and down within the barrel-channels in the
muzzle spindle 77 sufficiently as not to become distorted or kink
when the muzzle-spindle 77 rotates, the joint 84 between the
terminus of the barrel-tubes and the metal spindle is flush fit but
not fastened. The extent of this rotation and equivalent
compensatory longitudinal excursion in the barrel-channel of the
distal ends of the barrel-tubes, which terminate at muzzle-ports
(that facing the viewer being 88), is slight, the maximum required
being 180 degrees for the tractive electromagnets 80 to be directed
at any angle.
[2844] Radially situated barrel-tubes 74 must be free to bend in
response to the axial rotation of the spindle and therefore cannot
be encased in metal. With nonessential metal removed, the proximal
portion of the spindle between rotary joint 63 and the rotating and
reciprocating flush joints 84 into which the distal ends of the
barrel-tubes are inserted define a space, the splay-chamber, having
a generally flared shape, the outer surface thus allowing blood to
pass all round into blood-grooves 66 along the broadest segment and
so entirely past the barrel-assembly.
[2845] As shown in FIGS. 48, 49, 65 and 66, a segment of convoluted
tubing elastic flex-ring 111 to which the spindle is bonded with a
long chain methacrylate cement just distal to its neck in the
turret-motor rotor and the throat or level where the spindle flares
radially and forward serves to:
[2846] 1. Improve steerability by allowing radial flexion of the
muzzle-head distal to the turret-motor at the convoluted
segment.
[2847] 2. Allow more blood to flow past.
[2848] 3. Absorb and dampen the shock of discharge recoil,
especially in an eccentric, hence, force-imbalanced, monobarrel or
when ejection is eccentric or not precisely simultaneous in a
radially symmetrical multibarrel.
[2849] 4. Insulate and so temperature isolate the rear portion of
the muzzle-head when heated by increasing the current to the
turret-motor stator to allow thermal angioplasty.
[2850] 5. Reduce the contact area of the external surface of the
muzzle-head with the lumen wall, thus reducing any resistance to
rotation of the muzzle-head by the turret-motor.
[2851] To both flex and damp as necessary, the material of the
convoluted segment must comply with lateral forces applied
gradually, such as in tracking, but resist those applied suddenly,
such as discharge recoil. The flexion provided by this joint, which
is made of tubing of a thickness and material, to include
coextrusions, that is optimized for the barrel-assembly, affords
improved steerability in tighter anatomical bends when the
barrel-assembly is advanced or withdrawn. Since the amount of
rotation for a given muzzle-port configuration is limited, the
airgun can be discharged during semiautomatic control using the
linear positioning table while the barrel-assembly continues
moving, with no distortion of the barrel-tubes as might affect the
exit velocity occuring.
[2852] More significant recoil shock absorption and damping is
obtained by incorporating a second elastic disk or annulus between
the ejection head and electomagnet assembly. To `tune` this second
damper for the multiple reaction modes essential to defray the
recoil characteristics associated with discharge from one or a
plurality of barrel-tubes from one and the same barrel-assembly,
the second damper can be simple, i.e., comprise a single elastomer,
or interpose different elastomers over its area, can be compounded
or laminated, and be ridged, serrated, triangular, square, or
sawtooth-waved in contour on one or both faces. Upon emerging from
the neck of the spindle journaled within rotor 82, the barrel-tubes
74 remain unattached until engaged in flush joints or
barrel-channels 84.
[2853] The barrel-tubes are accordingly rotated at their upper or
distal points of attachment alone. Alternately, the barrel-tubes
can be continuous up to and attached directly to the muzzle-ports
without the interposition of an upper spindle portion; however,
this tends to result in less than completely dependable bonding of
the distal ends of the barrel-tubes to the muzzle-ports as
required. When the barrel-tubes can be rotated by the turret-motor
without distortion or kinking with their distal termini fixed in
position, the junction with the barrel-channels in the spindle
portion of the muzzle-head can be bonded as described below. In
FIG. 39, roof 85 of upper recovery electromagnet chamber 87 of the
diametrically opposed pair contains spring-loaded double or opera
type door 86 leading to antemagnet chamber 87.
[2854] Nose i.e., the distal or front end 64 of the muzzle-head is
like that of the radial discharge monobarrel seen in FIG. 40, which
shows the positions of the recovery electromagnets in an ablation
or angioplasty-incapable barrel-assembly lacking the trap-filter in
the nose, radial projection units, laser, or burr radial discharge
barrel-assembly shown in FIG. 67. With such a system, one to four
or more miniball rotary magazine clips can be used in the same
airgun and one to four or more miniball discharge barrel-catheters
can be plugged into the airgun. By blanking out unneeded barrels at
the rotary magazine clip, a barrel-assembly with more barrel-tubes
than required can be used with fewer barrels.
[2855] In barrel-assemblies of three or more barrels, the
muzzle-ports are generally equally spaced about the muzzle
periphery. The applicability of equidistant muzzle-ports with and
without blanked rotary magazine clips is considered sufficient to
omit a capability to circumferentially situate muzzle-ports; for
eccentric lesions, barrel-assemblies with muzzle-ports fixed in
eccentric positions are used. Detachability of the muzzle-head from
the barrel-catheter could pose a risk of detachment while deployed
in a vessel, and with the muzzle-head unitized with the
barrel-catheter, the durability of the two components in a unified
embodiment is sufficient not to jeopardize losing the
proportionately much greater value of the muzzle-head due to
breakage.
[2856] For tight control under fluoroscopic and angioscopic
viewing, the use of polytetrafluoroethylene in radial discharge
barrel-assemblies, which consist of barrel-tubes, the
barrel-catheter containing these, and the muzzle-head, should
impart a torque or turning ratio approaching 1:1. Positioning is
assisted by adding angular displacement indicating tick marks to
the radiopaque markers about the barrel-catheter used to indicate
the length of catheter introduced. Should recovery by means of an
electromagnet be necessary, nonabsorbable miniballs are radiopaque
and may additionally be contrast marked with tantalum, for example.
Miniballs that must break down, such as those consisting of or
coated with medication and those with an outer coating of solder
that is to flow after having been placed, contain sufficient
ferromagnetic material to allow their recovery if dangerously
mispositioned.
[2857] Such are not completely encased or sealed with contrast such
as tantalum provided with separated markings at the surface to
expedite locating. Length-of-entry graduations are a standard
feature of angioplastic (angioplasty) guide-catheters.
Polytetrafluoroethylene tubing is inherently flexible (Young's
modulus=0.5 gigapascals); a barrel-assembly with a barrel-catheter
and 4 barrel-tubes of the material is still sufficiently flexible
for tracking. The flexibility can be reduced by coextrusion or
coating of the barrel-catheter with polypropylene (1.5 to2.0
gigapascals), for example. To provide low friction surfaces when
coextruded to affect flexibility, the outer surface of the
barrel-catheter and inner surfaces of the barrel-tubes are those
made of polytetrafluoroethylene.
[2858] Steering within the range of curvature that does not flatten
the barrel-tube or tubes so that these would jam can be assisted
with the aid of an external electromagnet to urge the muzzle-head
in the desired direction. To resist snagging and stretching injury,
the muzzle-head is wetted with heparin-saline solution and/or
lubricant, the rest of the barrel-assembly lubricated as specified
below shortly. Since the magnet antechambers at the front of the
muzzle-head are closed off by spring-loaded doors to present a
continous or monocoque outer contour without edges that would
scrape against the intima, these are pushed open to allow wetting
with heparin-saline solution.
[2859] To impart a mild curvature to the barrel-channels in a solid
block of metal would require that the solid block first be halved
and then be quartered along its long axis twice to allow half
barrel-channels to be milled into either face of the mating faces.
The quadrants would then have to be fastened back together by means
of an adhesive, which is not preferred. Due primarily to the
elasticity of the lumen wall in healthy tissue as a standard, the
range of impact forces functional in implanting the miniballs
subadventitially is wide; within this range, a difference in exit
velocity affects the distance the miniball travels through the
media and the length of the slit it cuts through the external
elastic lamina, which is negligible when the force of impact is
properly set.
[2860] That only diseased tissue warrants treatment, and such
tissue is capable of wide and unpredictable deviation from the
normal is responded to by preliminary tissue puncture resistance
testing means described below. With tantalum coated miniballs, the
distance traveled along the inner surface of the tunica adventitia
or outer fibrous jacket of the structure is observable
fluoroscopically. However, the close observation and recording of
wound production by such means necessitates the use of a high-speed
camera such as a Redlake's MotionPro.RTM. HS Series, EG&G
549-11 Microflash.RTM. or Cordin Dynafax.RTM. 350 using
preautolytic excised tissue under laboratory conditions.
[2861] To minimize the risk of stretching injuries from resistance
to advancement, withdrawal, and traversing a tortuous stretch of
vessel especially when steering is assisted through use of an
external (extracorporeal) electromagnet to attract the muzzle-head,
barrel-assemblies made of materials other than
polytetrafluoroethylene are coated with an external lubricious
coating such as ACS Microslide.RTM., Medtronic Enhance.RTM., Bard
Pro/Pel.RTM. or Hydro/Pel.RTM., or Cordis SLX.RTM.. Just before
introducng the barrel-assembly into the bloodstream, the
muzzle-head is wetted with a heperine-saline solution, and if the
barrel-catheter is not coated with or made of
polytetrafluoroethylene, the rest of the barrel-assembly is wetted
with a light coating of a well tolerated ophthalmic type lubricant
such as 1% or 2% single-chain hyaluronic acid (sodium hyaluronate;
oxycellulose; hydroxypropyl methylcellulose; hyaluronan) sold under
such trade names as Healon.RTM., Adatocel.RTM., Amvisc.RTM.;
IAL.RTM., or Biolon.RTM. diluted with saline solution; or glycerin
diluted with water.
[2862] For trackability or steerability to allow femoral or
brachial entry and thus eliminate the need for open exposure, the
tubing for a catheter to represent the barrel-tube in a single
miniball discharging barrel-assembly with a radial discharge
muzzle-head or a barrel-catheter containing multiple barrel-tubes,
or the material used in both, to be described, ideally have high
combined pliancy, or flexion without kinking or folding. The need
for pliancy, usually expressed in terms of flexural strength or
flexural modulus as defined by American Society for Testing and
Materials standard Document D790-03 entitled "Standard Test Method
for Flexural Properties of Unreinforced and Reinforced Plastics and
Electrical Insulating Materials," rises with the number, diameter,
and wall thickness of barrel-tubes, four barrel-tubes contained
within a barrel-catheter, for example, posing a stringent
flexibility requirement.
[2863] A number of medical grade, flexible, high fatigue strength,
bioinert, nondegradable, uncoated, and nonleaching
nonchemical-absorbing polymers that are free of polymerization
process chemicals and do not give off acidic plasticizer gas when
sterilized are suitable for use as barrel-catheters and tubes in
barrel-assemblies. Suitable barrel-tube materials include
polytetrafluoroethylene, which is lowest in friction but relatively
stiff, polyamide such as Dupont Nylon Zytel.RTM., or a polyurethane
elastomer, such as Dow Pellethane.RTM. 2363 and numerous similar
products. Due to the propulsive force of the airgun before the
relief control retrofitted or built in is used to bleed off or
moderate the pressure generated within the valve body, tubing
material with a higher coefficient of friction than
polytetrafluoroethylene but greater pliancy, such as low denisty
polyethylene, vinyl, or nylon are readily usable through vascular
bends, whereas stiffer tubing is not.
[2864] For anatomical bends that due to the relative stiffness of
polytetrafluoroethylene tubing make steerability resistive, a
superior solution is to use barrel-tubes of highly pliant polymers
such as Nylon 12 and Nylon 66, already approved for use within the
body, but lubricated as stated above and lined with a thin coating
of polytetrafluoroethylene for low friction, or slipperiness. By
varying the relative thickness of polytetrafluoroethylene and
polyamide in compound tubing, combinations of pliancy and stiffness
suitable for application to the apparatus to be described may be
obtained in different diameters over a wide range of tube internal
wall friction. Flexibility of the barrel-assembly over the length
to remain outside the patient equal to that applicable to the
length to be introduced is undesirable as gratuitously increasing
the rolling resistance to the miniballs unpredictably.
[2865] At the same time, flexibility sufficient to track anatomical
bends is imperative for distal lengths typically introduced into
the body. If made of the same material, then according to the
softness of this material, the internal barrel-tubes and
barrel-catheter containing these must not exhibit friction in the
`bores` proportional to the pliancy. A suitable combination of
pliancy and stiffness in the barrel-tubes can be obtained by
coextruding an inner layer of polytetrafluoroethylene within a soft
outer polymer where the relative thickness of the
polytetrafluoroethylene diminishes, incrementally changes, or
discretely changes at one distance distad. For increased stiffness,
the barrel-catheter and barrel-tubes can be made of different
polymers or coextrusions over the length of the barrel-assembly to
remain outside the body.
[2866] The pliancy of the barrel-tubes can also be varied along the
length of the barrel-assembly by using centering devices (FIGS. 39
and 41 thru 45) that vary the distance from the longitudinal
central axis of the barrel-catheter to the central axes of the
barrel-tubes. Specifically, over the distal length of the
barrel-assembly where flexibility to track anatomical bends in the
vascular system is essential, the barrel-tubes are perforated,
imparting greater flexibility to this length. Reduction in
stiffness in the distal portions of the barrel-assembly to be
entered into the body is also obtained by perforation of the
barrel-tubes and by using centering devices to be described to
position the barrel-tubes farther from the longitudinal axis of the
barrel-catheter.
[2867] The internal pressure generated by discharge of the airgun
is dissipated by using barrel-tubes with perforations over the
distal portion of the barrel-assembly to be introduced into the
body. These pressure relief perforations provide a path for the
relief of the airgun discharge pressure within the barrel-assembly
that is less resistant than the pressure that would be required for
the gas to enter the bloodstream. These perforations must be too
few, too spaced apart, and too small to cause folding or kinking of
the barrel-tubes as the barrel-assembly is advanced
transluminally.
[2868] By situating these barrel-tube perforations toward the
distal end of the barrel-assembly, the distal segment that must be
more flexible to follow the curves of vessels are rendered more
flexible. The number, shape, and location of these perforations is
a factor in determining the pliancy of the barrel-tubes and the
barrel-assembly as components therein. To place blood flow
side-holes in the barrel-catheter as well and thus achieve even
greater flexibility is disallowed by the need for this space to
equalize the pressure within the barrel-assembly during discharge
while immersed in blood without introducing gas as bubbles into the
bloodstream.
[2869] While to reduce friability due to rotary magazine clip-hole
adhesion or barrel friction and any tackiness, a light coating of a
well tolerated ophthalmic type lubricant such as 1% or 2%
single-chain hyaluronic acid (sodium hyaluronate; oxycellulose;
hydroxypropyl methylcellulose; hyaluronan) Healon.RTM.,
Adatocel.RTM., Amvisc.RTM.; IAL.RTM., or Biolon.RTM. diluted with
saline solution; or glycerin diluted with water may be applied to
miniballs with a medicated outer coating of dried syrup, separate
lubrication as might variably accumulate along the barrels
introducing mechanical uncertainties and possibly forming a film
over the muzzle-port by surface tension that might additionally
congeal not permissible.
[2870] Pliancy, however, tends to vary as twisting, hence, the
turning or torque ratio, which with a passive or nonmotorized
muzzle-head, is ideally 1:1, and the coefficient of friction of the
barrel tubing material, which is significant as the guideway for
the miniballs. The coefficient of friction is determined with the
aid of an Instron.RTM. or similar tester, such results provided by
the tube maker. Turning ratio is more significant when the implants
must be placed at particular circumferential angles. Since the
airguns used generate sufficient propulsive force to project almost
any interventially functional number and diameter of miniballs
through respective barrel-tubes from the point of entry, usually
inguinal, to the treatment area, such as at the heart, through
rolling resistance comprised of bends in polymeric tubing of any
coefficient of friction, and this force can be controlled, pliancy
is the dominant consideration.
[2871] As is conventional with guide-catheters, barrel-assemblies
are marked off in distance increments and indicate resistance to
rolling per unit length at a standardized degree of bending or
radius of curvature that must be coordinated with required force of
impact data for different tissues. Barrel-assemblies with plural
barrel-tubes display a number or other distinctive marking for each
produced by inclusion in the mold used to make the proximal end-cap
and by engraving the same mark next to each muzzle-port. When the
barrel-assembly must be coursed along a different route than the
preparatory angioplasty, access through a separate incision is not
significantly traumatic and has been made relatively safe.
[2872] Broadly, conventional stenting is preferrable in geriatric
and terminal patients, whereas application of the methods and
apparatus described herein are preferable where life expectancy
recommends avoiding sequelae. Barrel-assemblies with multiple
barrel-tubes are for use in smaller diameter vessels and ducts,
usually around 6 to 10 French, or 2 to 3.3 millimeters, especially
in the arterial tree, where operating time should be kept to a
minimum. For this reason, it is desirable to discharge multiple
miniballs at once and in quick succession. The structure of the
barrel-assembly thus allows radial discharge and the airgun is
semiautomatic.
[2873] At the same time, dependable means for preventing miniballs
from escaping into the bloodstream must be provided. Shown in FIG.
38, whether antegrade or retrograde, a barrel-assembly for use in
the vascular tree displaces blood upon introduction into the
bloodstream and must incorporate features to prevent ischemia due
to obstruction to the flow of blood or a partial blockage that
results in hypoxemia. The other type ductus where obstruction to
oxygenation must be minimized is in the airway, where a radial
discharge barrel-assembly must be advanceable and withdrawable
within a lumen slightly larger in diameter than the
muzzle-head.
[2874] Such a barrel-assembly must therefore provide paths for the
blood or air to move past it. For this purpose, the muzzle-head is
kept at least 10 percent smaller in outer diameter than the lumen.
The same limitation does not apply to gastrointestinal or
urinogenital (urogenital) ductus where oxygen dependency is less
immediate and the lumen can be purged before entry. To allow some
blood to pass even when the muzzle-head unexpectedly occludes or
obturates the lumen, the muzzle-head is provided with longitudinal
blood-grooves or furrows 66 on its outer surface midway between the
barrel-tube 74 exit-holes 71. The blood-grooves continuous over the
muzzle-head to include both the proximal or muzzle-port and distal
or electromagnet sections allow some pulsation to pass the
barrel-assembly.
[2875] Some limited transmission of the pulse through the
barrel-assembly is obtained by means of side holes through the wall
of the catheter barrel (see De Bruyne, B., Stockbroeckx, J.,
Demoor, D., Heyndrickx, G. R., Kern, M. J. 1994 "Role of Side Holes
in Guide-catheters: Observations on Coronary Pressure and Flow,"
Catheterization and Cardiovascular Diagnosis 33(2):145-152). The
side grooves or side hole tunnels are connected by means of
peripheral tangential tunnels that course diagonally relative to
the longitudinal axis. The placement and angles of these flow
through tunnel tubes can also be used to buttress and stiffen the
barrel-assembly over designated segments along its length. Several
different materials and manufacturing techniques can be used to
produce the one to four or more way radial discharge
muzzle-head.
[2876] The preferred embodiment consists of micromachining and
micropolishing a solid block of stainless steel into front or
ejection head and rear motor housing portions. The structure of the
muzzle-head is the same regardless of the number of barrels or
circumferential angle of the barrel exit ports, and a variety of
double barreled or two-way barrel-assemblies in various sizes may
be necessary to allow variation in implantation angles. Passivation
to remove surface contaminants or to improve the appearance of the
muzzle-head, which is highly polished, is unnecessary, but is
desirable for enhancing corrosion resistance. Made thus, the
barrel-tube channels that contain the barrel-tubes in the
muzzle-head are machine or micromachine drilled, hence, straight
throughout their length.
[2877] To allow the mild curvature of the barrel-tubes necessary to
diverge, that is, to splay or veer outwards to be redirected from
the parallel orientation in the barrel-catheter to the
circumferential placement of the muzzle-ports about the periphery
of the muzzle-head, a splay space or splay chamber is interposed
between the barrel-catheter receiving recess or socket at the
proximal end of the muzzle-head and the entry of the distal ends of
the barrel-tubes into their respective similar but smaller sockets
in the proximal surface of the upper or distal portion of the
muzzle-head which continues the barrels to the muzzle exit ports.
The length of this space or splay chamber depends upon the wall
thickness and pliancy of the barrel-tube material.
[2878] The underside of the upper, barrel-channel portion of the
muzzle-head, or ceiling of the splay chamber has four openings to
receive the four small gauge barrel-tubes one each into a
barrel-channel. The proximal or bottom end of the muzzle-head
includes a collar or neck to receive the barrel-catheter containing
the barrel-tubes. Most often the pliancy of the barrel tubing
material will necessitate that the distal ends of the barrel-tubes
be able to rotate and reciprocate within flush joints containing
barrel-channels 74 of the metal portion of the muzzle-head that
terminates with the muzzle-ports or exit-holes.
[2879] However, provided the outer surfaces of the
polytetrafluoroethylene barrel-tubes in contact with the walls of
the barrel-channels are not excessively rotated and have sufficient
slack to avoided distortion of their bores when rotated by the
turret-motor, these are primed or etched with a special purpose
chemical such as Acton Technologies, Inc. FluoroEtch.RTM. or W.L.
Gore.RTM. and Associates, Inc. Tetra-Etch.RTM. or blown-ion air
plasma type corona, or flame surface treated and coated with an
adhesive suitable for bonding etched polytetrafluoroethylene to
stainless steel, such as NuSil Technologies MED-1037 or MED3-4013
then threaded up through the bottom holes of the splay chamber
ceiling until exiting the vertically oblong muzzle barrel
openings.
[2880] The ends are then cut and polished flush to the surface of
the muzzle. The barrel-catheter is then slipped over the set of
four barrel-tubes until it is brought just short of the socket or
receiver for it formed by the collar at the proximal or bottom end
of the muzzle-head. The outer surface of the barrel-catheter to
engage the socket at the bottom or proximal end of the barrel tip
is etched and the same adhesive applied before its upper end is
inserted into the socket. An alternative method for producing two
and four-way muzzle-heads over a range of diameters from about 7 to
10 French is polytetrafluoroethylene thermoforming by resin
transfer-molding, which is well known to those skilled in the art
of plastic molding.
[2881] Made thus, the polymeric muzzle-head should nevertheless
contain ferromagnetic inclusions to preserve steerability and
abutment with the assistance of external electromagnet. Since the
barrel-catheter and barrel-tubes as well as the barrel tip are all
likely to be made of polytetrafluoroethylene, conventional
polytetrafluoroethylene resists self-bonding, and the
barrel-catheter and barrel-tubes would not be molded in one piece
with the barrel tip, a special polytetrafluoroethylene molding
material such as E.I. Dupont de Nemours Teflon NXT.RTM. is used. If
the muzzle-head is cast, then positive inserts in the mold can be
used to yield mildly curved barrel-tube channels eliminating the
need for a splay space.
[2882] Preferred is a barrel-assembly which comprises the
barrel-catheter and muzzle-head in a single unit that plugs into
the barrel of the airgun. The barrel-assembly comes with rotary
magazine clips containing test miniballs and should never be used
with test miniballs of different specification. To incorporate the
rotary magazine clip chamber at the proximal end of the
barrel-catheter as unitized is not preferred, because this
necessitates a communicating arm or intromitting pawl from the
airgun. As a matter of terminology, the switch or trigger actuator
and pressurized gas cylinder or canister represent the minimum
distinctly airgun portions of the apparatus described herein.
[2883] The barrel-catheter and barrel-tube sockets consist of
internal diameter flush joints, meaning the wall thickness of the
inserted tubes is accommodated by the surrounding material of the
receptacle so that there is no change in the internal diameter of
the lumen at the joint. The end of the barrel and proximal end of
the barrel-assembly are keyed to assure proper alignment, which the
1:1 turning ratio of the barrel-assembly supports. In an off the
shelf airgun modified for use in accordance with the objects set
forth herein, the barrel insert used to reduce the caliber stops
half way down the barrel to allow the proximal end of the
barrel-assembly to be inserted.
[2884] Barrel-channels that avoid angles throughout their course
yield a smoother or more linear relation of propulsive force to
exit velocity. An angle in the barrel-tubes too slight to stop the
miniball at lower velocities nevertheless dissipates its momentum
or propulsive force. While a steep gap in exit velocities separates
implantation force of impact values from puncture of the outer
fibrous layer of the ductus, variation in exit velocity directly
effects the distance of miniball travel along the inner surface of
the fibrous outer layer before it is brought to a stop.
Overshooting or overtravel is readily compensated for by
withdrawing the muzzle-head by the proportionally corresponding
distance, but is to be avoided as imposing needless additional cell
damage and edema.
[2885] Because the exit velocities smaller than that necessary to
reach a nonspecific subadventitial position while not puncturing
the outer fibrous jacket or tunic of the ductus cover a range of
impact force values, adjustment in the exit velocity need not
achieve inordinate exactitude merely to achieve subadventitial
placement while not posing a risk of puncture. At the same time,
changes in distance or depth into the vascular system are not
accompanied by any change in the chamber to muzzle-head length of
the barrel-assembly. Thus, the small decrements in depth required
to withdraw the muzzle-head to place successive discharges exert no
effect on the ability to place the miniballs at the prescribed
relative distances along the ductus.
[2886] However, the subpuncture range of exit velocities equate to
equivalent impact forces that while spread out in value by the
tunica adventitia, or outer elastic lamina, and consistent from
discharge to discharge as to allow successive termini to be
accurately placed as to related position, nevertheless propel the
miniballs to correspondingly different distances within the softer
tunica media along its inner surface. To achieve a certain miniball
trajectory terminus in relation to distance from the muzzle-head
and therefore avoid needless smooth muscle trauma requires tight or
precise control. This combination of factors means that from a risk
of puncture standpoint, the intitial discharge, while preferably
purposeful in terms of treatment, is subcritical and allows the
distance travelled by the miniballs to be noted with the aid of the
several imaging techniques available.
[2887] Any over- or under-shooting is then corrected by adjusting
the exit velocity in proportion to its extent. Since the pathology
is likely to have changed the mechanical properties of the tissue,
a preliminary test discharge at a distance from the lesion to be
treated is not recommended. As any site aside from that diseased
will present different properties, an initial test discharge
anywhere but into the diseased tissue to be treated will not yield
dependable data. For this reason, implantation is begun with the
airgun set for the exit velocity or force of impact value predicted
with the aid of tables supplied with the apparatus for tissue of
like condition to seat the miniball subadventitially without
overshooting along the inner surface of the fibrous outer
layer.
[2888] Due to the tiny diameter and bioinertness of the miniballs,
perforation through the adventita into a body cavity of a miniball
should seldom result in any significant trauma, such as a
hemorrhage or the leakage of lumen contents. In ductus other than
arteries, inflammation, bleeding, and proteinaceous exudate quickly
seals such a wound. In an artery, however, the internal pressure of
the pulse and the fact that platelet blockade has been administered
mean that perforations can lead to problematic bleeding that must
be prevented. This is accomplished by prepositioning the
stent-jacket or stent-jackets, which may be of the double-wedge
type, as addressed above in the section entitled Double-wedge Stent
and Shield-jacket Rebound-directing Linings. Provided a coagulant
(hemostat) is applied to the internal surface of the prepositioned
stent-jacket, bleeding is quickly stopped even if a perforation
does occur.
[2889] Whether requiring to be coated for radiopacification,
miniballs are highly radiopaque and retrievable by means of an
endoscope introduced through the incision made to place the
stent-jacket. The results of the initial airgun discharge are
carefully evaluated and used to adjust the discharges to follow.
The means for preventing the accidental release of a miniball
within the tracheobronchial tree or vascular system and removing
any spillage of intestinal contents or bile following inadvertent
puncture is discussed below. Restraint of the ductus wall from
radial excursion at and about the point of impact would reduce the
impact force required to puncture the wall; however, both wall and
material of the stent-jacket are sufficiently elastic to comply
with movement of the wall at and about the point of impact.
[2890] The stent-jacket is compliant both internally as to absorb
the displacement of the wall in response to the impact of
implantation, and as a result of its overall conformation, which
includes a slit cut entirely along one side, elastic in response to
the gross movement of the smooth muscle in the ductus wall.
Spillage of contents into the surrounding body cavity as the result
of accidental puncture of the urinary tract or bile ducts is
responded to by aspirating the spillage through the incision made
to insert the stent-jacket. Since it is compliant, the
stent-jacket, or extraductal surround component of the stent, can
be placed either before or after the intraductal component
consisting of the full complement of miniballs has been
implanted.
[2891] Inserted before the miniballs, the stent-jacket may exert a
slightly nonuniform effect upon terminal velocity and eccentric
compression of the lumen wall about the lumen circumference against
the muzzle-head but assists in retaining the miniballs. This
attraction assists in preventing rebounds or failures of impact
force as would release a miniball into the lumen. The accidental
release into the lumen of a miniball is minimized when the
muzzle-head fits snuggly within the lumen, damping eccentric
reactive accelerations or recoils without compressing the wall.
Excessive compression of the wall interferes with the ability of
the wall to comply with the impact and thus the ability to properly
implant the miniballs. The mechanical and electrical connections of
barrel-assemblies to airguns is discussed under sections to
follow.
[2892] VII2d(3). Ablation and Angioplasty-Incapable Radial
Discharge Barrel-Assembly Muzzle-Heads
[2893] The barrel-assembly is configured to minimize obstruction to
the circulation. To allow sufficient torque, the windings of the
turret-motor are elongated rather than widened. In center-discharge
embodiments, the spindle can be narrowed to a flared throat,
muzzle-heads larger in diameter provided with blood-grooves.
Ablation and ablation and angioplasty-capable barrel-assemblies
incorporate additional components such as radial projection units,
heat-windows, and side-sockets that compete with the number of
barrel-tubes for diameter. Otherwise, even combination forms as
addressed below, are configured similarly.
[2894] The ability to perform certain endoluminal functions with
single entry such as injection a significant adjunct to stenting
implantation, practical barrel-assemblies generally include only
the radial projection units and tool-inserts to perform this
essential function. For stenting not to be preceded by an ablation
or an angioplasty, the units and tool-inserts to perform this
function can be eliminated. Bipartite construction, as addressed
below in the section entitled Distinction in Ablation or
Angioplasty-capable Barrel-assemblies as Unitary or Bipartite, can
compensate for the inability to produce a general purpose device in
the small diameters. In minimally and fully ablation and ablation
and angioplasty-capable barrel-assemblies, push-arm blank
tool-inserts can be used to nudge the muzzle-head aside clearing a
path for blood to pass.
[2895] To prevent recoil deformation at the curves where the
barrels approach the barrel-ports, which would dissipate much
expulsive force (kinetic energy, momentum, impact force) according
to the deformation, and brake (slow down) if not jam the spherules
on exiting, polymer barrel-tubes are discontinued, the exit
passages continued forward as barrel-channels drilled through an
ejection-head machined from a solid block of nonferrous metal. The
distal ends of the barrel-tubes that project into the
barrel-channels are slightly smaller in diameter to allow these to
move forward or backward upon, thus allowing, rotation.
[2896] Muzzle-heads conform to either of two configurations, one
with barrel-tubes longitudinally centered, the other with
barrel-tubes more peripheral to allow a laser catheter or rotary
burr to be incorporated at the center. Both include a convoluted
elastomeric segment that serves as a damper and point of flexion.
Elongation of the muzzle-head through use of a turret-motor winding
that is enlarged in length rather than diameter allows a level of
torque to be developed that would otherwise deny access to narrower
vessels or other ductus and results in a longer contact area with
the lumen wall over which directable angioplasty tools such as
thermal windows and side-sweeping brush type radial projection unit
tool-inserts can be made to apply.
[2897] VII2d(3)(a). Monobarrel Radial Discharge Barrel-Assembly
Muzzle-Heads
[2898] VII2d(3)(a)(i). Structure of Monobarrel Radial Discharge
Barrel-Assembly Muzzle-Heads
[2899] FIG. 38 shows an external view of a single barrel
(barrel-tube) radial discharge barrel-assembly, and FIG. 39 a view
partially in longitudinal section of a two or three barrel
barrel-assembly. While a simple pipe type monobarrel
barrel-assembly is intended for use primarily in the
tracheobronchial tree and never in a duct or blood vessel, a radial
discharge type barrel-assembly can be designed for use in a narrow
ductus with substantially undifferentiated anatomy of the lumen
wall, and provided certain features are added, in the bloodsteam.
Ischemia capable of inducing a midprocedural infarction a primary
risk, a barrel-assembly for use in the bloodstream incorporates
blood-tunnels, and in the muzzle-head, blood-grooves to minimize
obstruction to the flow of blood.
[2900] The use of a multiple-barrel barrel-assembly, especially
when automatically advanced, rotated, and withdrawn by means of a
positional control system, is not sought only to achieve the
uniform placement of the miniball implants in a formation and thus
a more uniform distribution of forces, but to achieve operative
speed in order to reduce the risk of infarction. Means for avoiding
abrupt closure are discussed above in the section entitled Risk of
Abrupt Closure. To be usable in the bloodstream, the gas pressures
generated during discharge must be prevented from entering the
bloodstream as gas embolisms. This necessitates enclosing or
jacketing about the barrel-tubes over the entire length of the
barrel-assembly and providing gas return channels so that such
pressures are dissipated within the enclosure.
[2901] The barrel-catheter represents this jacket up to its distal
extremity, and the ejection-head at the front of the muzzle-head
contains gas return tubes to channel the pressures back into the
barrel-catheter central canal. A one-way safety valve, usually an
elastomic slit-valve in end-plate 99 (not shown) is present to
outlet higher pressures. In small diameter ductus, the muzzle-head
enclosure additionally serves to prevent injury by an exposed
pointed muzzle. The enclosure additionally incorporates a shock
absorbing joint both to lend flexibility for tracking and dissipate
any recoil upon discharge.
[2902] The parts shown in FIG. 38 are marked to clarify the parts
of the distal (forward) portion of the barrel-assembly, or
muzzle-head as consisting of:
[2903] 1. A barrel-catheter 44 journaled within turret-motor
clamping collar 59.
[2904] 2. A turret-motor within housing 61.
[2905] 3. A flex-joint 111.
[2906] 4. A spindle 77, consisting of:
[2907] a. A neck portion journalled within the rotor of the
miniature through-bore torque type turret-motor, which is the
separated distal segment of barrel-catheter 44.
[2908] b. A spindle throat 112 beginning distal to the level of
emergence from the turret-motor rotor, of which the forward portion
wherein the barrel-tubes flare distoradially is designated the
spindle flare frame or chamber. c. An ejection-head 112, which
conveys the distal ends of barrel-tubes 74 to exit-holes 71,
and
[2909] 5. A muzzle-dome consisting of:
[2910] a. A recovery electromagnet assembly (not shown in the
outside view of FIG. 38 but situated short of nose 64), and
[2911] b. Nose 64, of which the facing aspect is the nosing, which
in most practical barrel-assemblies, encircles a scope that
projects through the center of a heat-window.
[2912] Spindle 77 of muzzle-head 70 must be able to rotate through
180 degrees to either side, i.e., clockwise or counterclockwise.
While a continuous length of very pliant tubing barrel made of a
polymer such as vinyl and given enough slack can be rotated through
a semicircular arc without distorting the `bore,` most materials
are not so flexible and therefore necessitate a rotary joint. When
the momentum of the miniballs on exiting and the strength of the
barrel-tubing material allows, both lumens of a double lumen
extruded tube can proceed to the inner surface of muzzle-head 70
with only one of the two actually open to the exterior through
muzzle-port 71 as barrel-tube 74. The second lumen is then sealed
by the internal surface of the muzzle-head and is placed in
communication with the first through a distal hole.
[2913] The pressure built up in the lumen used as a barrel-tube
then returns through the second, sealed off lumen. The accompanying
lumen adds strength; however, when the barrel-tubes are continuous
from one end of the barrel-assembly to the other, a lengthier arc
for bending required, deformation becomes more pronounced as the
number of barrel-tubes is reduced and the angle of rotation
increased, so that with one barrel-tube, reduction in exit
muzzle-port 71 and a susceptibility to jamming increases in
likelihood. This is ameliorated by providing a reciprocating and
rotating flush joint wherein the internal diameter of the `bore`
remains constant in a less prominent or reduced ejection head.
[2914] Referring now to FIG. 38, rotary joint 58 is formed by
transecting division of barrel-catheter 44 flush to the distal
surface of clamping collar 59, clamping collar 59 in turn immovably
affixed to the rear of throughbore turret-motor in housing 61 and
stator 62, so that only the distal segment of barrel-catheter 44
separated to create a rotary joint and journaled within
through-bore rotor 60 of the turret-motor rotates with rotor 60,
and since muzzle-spindle 77 is attached to the distal end of the
distal end of the distal segment, spindle 77 is rotated.
[2915] Viewed from the outside, rotation is seen only distal to the
turret-motor in housing 61, comprising spindle 77 and the parts of
the muzzle-head 70 distal to it, visibility of the rotor journaled
distal segment as the rotor inserted stem portion of the of spindle
77 denied, creating the impression that the rotary joint is at the
front of the turret-motor and spindle 77 rather than at the
opposite or proximal end of the turret-motor. A simple pipe
monobarrel-type barrel-assembly is manipulated by hand and does not
incorporate a remote actuator to rotate muzzle-head 70 by wire
remote control. In a single-barrel radial-discharge
barrel-assembly, barrel-catheter 44 is synonymous with the one and
only barrel-tube.
[2916] Whether such or conducting a plurality of barrel-tubes in a
multiple barrel radial discharge barrel-assembly, the segment of
barrel-catheter 44 distal to rotary joint 58 and journaled within
through-bore rotor 60 of the turret-motor rotates in coaxial
relation to the stationary segment of barrel-catheter 44, which is
proximal to rotary joint 58 clamped by collar 59 to the rear of
turret-motor housing 61. By contrast, the multiple barrel-tubes in
a multiple barrel barrel-assembly (which is always of the radial
discharge type), continue without break through the encircling
rotary joint 58 in the barrel-catheter, passing therethrough
off-center or arranged at a slight distance around the longitudinal
center of barrel-catheter 44.
[2917] For this reason, when these insert into the ejection head at
their distal ends, rotation of muzzle-ports 71 is driven by
rotation of the ejection head Accordingly, the proximal segment of
the barrel-catheter, clamping collar, and motor housing 61 remain
stationary while the distal segment of the barrel-catheter that
follow the rotary joint rotates. Since the barrel-tube or tubes are
continuous through the rotary joint, the `bore` or `bores` for
discharge are seamless. When barrel-catheter 44 in FIG. 38 is made
of a material and in a thickness that becomes too soft when heated
to 90 degrees centrigrade, such as by the turret-motor stator at
stall while used for thermal angioplasty, clamping collar 59 is
made of a low heat conductivity and transmissive polymeric
material.
[2918] In larger embodiments, provided the flexibility of the
barrel-catheter is not significantly affected, clamping collar 59
can be machined out of metal lined with a thermal insulant. In the
largest embodiments, the insulation can be paper, cotton, pith, or
felt. In embodiments of intermediate size, provided the
barrel-catheter is thick enough as not to become limp or flaccid,
the clamping collar can be bonded to the barrel-catheter with a
synthetic elastomer insulating adhesive, which are numerous. The
direct-current silver wire-wound subminiature through-bore torquer
turret-motor is described in greater detail under the section on
motorized turret muzzle-heads below. The neck or segment of the
barrel-tube distal to this cut is journaled in the through-bore
rotor 60 of the turret-motor and thus freely rotated by the
turret-motor.
[2919] The elements of the muzzle-head distal to this joint are
unitized or monolithic, so that the portion of the barrel-tube
within rotor 60 functions as a shaft that rotates the spindle and
electromagnet assembly as a unit. As seen in FIGS. 38, 39, 48, 49,
65, and 66, the unitized spindle and electromagnet assembly
portions of the muzzle-head distal to the swivel motor rotate about
joint 58. As shown in FIGS. 38, 48, 49, 65, and 66, a segment of
convoluted tubing 111 intervenes between the spindle throat or
level where the spindle flares radially outward and the neck, or
segment of the barrel-catheter that is distal to the rotary joint
and within the turret-motor rotor.
[2920] The multiple functions and bonding of this convoluted
segment to the spindle and nect are described below. The amperage
to the electromagnet is controlled by a precision multiturn digital
potentiometer that allows the muzzle-head to be nudged against the
lumen wall without additional field strength as could injure the
wall or so compress the tunica media as to preclude undercutting it
for subadventitial placement. Luminal wall compression can to an
extent be compensated for through the use of a swellant.
Alternatively, the muzzle-head spindle can be made of
polytetrafluoroethylene, for example, by micromachining with or
without prior transfer-molding.
[2921] Since unlike a simple pipe, some single barrel radial
discharge barrel-assemblies must be usable in the vascular system
where the loss of a miniball must be prevented, the tractive
electromagnet assembly in a radial discharge barrel-assembly
consists of two electromagnets of opposing polarity, of which only
the magnet of the pair 64 closer to the viewer is shown in FIG. 39.
The magnet assembly 64 and independent control of each
electromagnet is described below in the section devoted to
electromagnet assemblies. FIG. 40 is a cross section view of the
nose or distal end of the single barrel radial discharge
barrel-assembly showing the tractive electromagnets 65 and
blood-grooves 66 to permit some passage of blood past the
muzzle-head. Blood-grooves 66 can be made to pass midway between or
over the barrel-tube exit-holes (muzzle-ports).
[2922] In FIG. 40, to clear magnets 65 when opening and closing,
spring-loaded trap doors are paired, that is, of the double or
opera type. Continuous with the indentation formed by the front of
the two magnets 65 of the magnet assembly 64 indicated in FIG. 40,
blood-grooves 66 are made as deep as possible to run longitudinally
along the entire length of the muzzle-head without necessitating an
increase in the outer diameter of the barrel-catheter or
encroaching upon the barrel-tube, the muzzle-port 71 in FIG. 38, or
magnet assembly 64. Because a radial discharge barrel-assembly such
as that shown in FIG. 38 must enclose the parts equivalent to those
in a simple pipe type barrel-assembly within a shell for use in
smaller ductus wherein gases must be contained and rounded contours
are imperative, barrel-tube 74 and barrel-catheter 44 are not one
and the same as in the simple pipes of FIGS. 31 thru 34.
[2923] The magnet antechambers seen in FIG. 40 as 67 behind the
spring-loaded trap double doors 68 are addressed below in the
section entitled Factors that Affect Muzzle-head Nosing Length or
Reach, Steerability, and Trackability. Arrows 69 indicate the path
of a recovered miniball, which may have become loose or required to
be extracted having been misplaced upon implantation through the
double door to become trapped within magnet antechambers 67. The
diameter of the barrel-assembly that can be used in any ductus is
limited by the requirement to avoid stretching injury and in blood
vessels, ischemia as well.
[2924] The lumina in the coronary arteries in adults vary between
1.5 and 5.0 millimeters (see, for example, Dodge, J. T. Jr., Brown,
B. G., Bolson, E. L, and Dodge, H. T. 1992. "Lumen Diameter of
Normal Human Coronary Arteries. Influence of Age, Sex, Anatomic
Variation, and Left Ventricular Hypertrophy or Dilation,"
Circulation 86(1):232-246; Mosseri, M., Zolti, E., Rozenman, Y.,
Lotan, C., Ershov, T., Izak, T., Admon, D., and Gotsman, M. S.
1997. "The Diameter of the Epicardial Coronary Arteries in Patients
with Dilated Cardiomyopathy," International Journal of Cardiology
62(2):133-141), imposing a severe demand for miniaturization. This
factor makes application for pediatric use difficult,
barrel-assemblies suited to the smallest patients generally limited
to a single barrel-tube, or monobarrel.
[2925] While the withdrawal of one barrel-assembly and insertion of
another is acceptable in the airway when space affords unobstructed
maneuverability and the possible complications of a luminal entry
wound are not a factor, entry in the vascular system is best
singular. Unless the benefit in operative speed gained with a
multiple discharge radial barrel-assembly justifies replacing it
with a barrel-assembly of smaller diameter having fewer barrels,
minimizing the risk of entry point complications usually
discourages such technique. Thus, even though a vessel or duct may
admit a muzzle-head of larger diameter and more barrels upon entry,
access to the smallest gauge of the vessel or duct should dictate
the diameter of the barrel-assembly used; that is, treatment is
best accomplished by using a muzzle-head of a diameter that will
allow access throughout the length to be implanted.
[2926] VII2d(3)(a)(ii). Materials of Radial Discharge
Barrel-Assembly Muzzle-Heads
[2927] The muzzle-head is preferably made of a nonmagnetic
austenitic stainless steel, such as 18-8, 304, or 316 amenable of
hardening in smaller thicknesses. Alternatively, numerous polymers
can be used. The core of the tractive electromagnets at the distal
end of the muzzle-head and components of the turret-motor if
present, however, allows the use of an external hand-held
electromagnet to expedite steering, and in a larger vessel, make
possible the quick positioning of the round tip in stable abutting
relation to at particular position along the lumen wall. When the
brushes are separately controllable, the radial projection unit
feature described below can also be used to nudge the muzzle-head
eccentrically within a lumen, but only in a lumen little greater in
diameter than the muzzle-head itself, and with the barrel-assembly
stationary.
[2928] Limited thus, the potential utility of an external hand-held
electromagnet stands. Alternatively, the muzzle-head can be made of
any nonferrous metal of suitable hardness and tissue compatibility
or a resin by transfer-molding. For precision and hardness, it is
micromachined of a nonferromagnetic stainless steel such as
austenitic 18-8 (18 percent chromium, 8 percent nickel), 304, or
316, and then given an outer coating of polytetrafluoroethylene
(polytetrafluoroethene) (see, for example, Hanssen, H. H., Wetzels,
G. M., Benzina, A., van der Veen, F. H., Lindhout, T., and Koole,
L. H. 1999. "Metallic Wires with an Adherent Lubricious and
Blood-compatible Polymeric Coating and Their Use in the Manufacture
of Novel Slippery-when-wet Guidewires: Possible Applications
Related to Controlled Local Drug Delivery," Journal of Biomedical
Materials Research 48(6): 820-828).
[2929] A hydrophilic coating such as applied by the SlipSkin.RTM.
reel-to-reel process, for example, allows a platelet blocker, for
example, to be infused into the coating (see, for example, Koole,
L. H. and Hanssen, J. H. L. 2001. "Wire, Tube or Catheter with
Hydrophilic Coating," European Patent 1104681. Alternative coating
processes such as plasma vapor deposition apply a coat that is
thicker. Sputter coating erodes and plasma contaminates the surface
of the steel (see, for example, Bastasz, R. and Thomas, G. J. 1978.
"Surface Analysis of Sputtered Stainless Steel," Journal of Nuclear
Materials 76-77:183-187; Clausing, R. E., Emerson, L. C., and
Heatherly, L. 1978. "Sputtering and Chemical Attack of 304
Stainless Steel, Aluminum, and Gold by Hydrogen Ions of 100 eV
Energy," Journal of Nuclear Materials 76-77:199-201). This coating
is applied to the entire outer surface of the muzzle-head, to
include the interior surface of radial projection unit shafts, or
wells.
[2930] The single barrel radial discharge barrel-assembly is
similar to the multiple barrel radial discharge barrel-assemblies
to be described in materials, in incorporating a motorized turret
to rotate the tip, in having paired trap-extraction electromagnets
64, and in the overall form of the muzzle-head 70, which differs
only in including but a single muzzle-port 71. As with a simple
pipe barrel-assembly, the miniballs fed to such a single pipe
barrel-assembly can be delivered from a linear queue type magazine
clip, which unlike a rotary magazine clip is, however, limited to
one miniball per discharge. It is the only barrel-assembly where
rotation is by an axial rotary joint.
[2931] The barrel-catheter 44 of a radial discharge barrel-assembly
such as shown in FIGS. 38, 39, 48, 49, 65, and 66 has a motorized
turret to rotate the muzzle-head inside the lumen and therefore
does not depend upon a particluar choice or combination of tubing
materials and/or thickness thereof as would interfere with
trackability and torqueability. A single barrel radial discharge
barrel-assembly made for use in the vascular tree can also be used
in a secondary or tertiary bronchus or ureter, for example. When
made of a sufficiently nonelastic and slippery material such as
polytetrafluoroethylene having a larger wall thickness or as the
outer layer in a coextrusion, the distal ends of the barrel-tubes
are inserted with no bonding into the flush sockets that represent
the start of the barrel-channels in the ejection-head.
[2932] This allows free rotation and reciprocation of the distal
ends of the barrel-tubes. The inner edge of the sockets are beveled
to minimize the effect upon the exit velocity of a miniball that
might strike the edge. When, however, the barrel-tubing is
sufficiently pliant that the bore is not unduly distorted or its
distal end dislodged from the socket during discharge, bonding is
essential. When made of polytetrafluoroethylene-coated nylon, the
outer surface of the barrel-catheter is primed by etching with a
special purpose chemical such as Acton Technologies, Inc.
FluoroEtch.RTM. or W.L. Gore.RTM. and Associates, Inc.
TetraEtch.RTM. or blown-ion air plasma type corona, or flame
surface treated, and coated with an adhesive suitable for bonding
etched polytetrafluoroethylene to stainless steel, such as NuSil
Technologies MED-1037 or MED3-4013.
[2933] VII2d(3)(b). Muzzle-Head Turret-Motor
(Turret-Servomotor)
[2934] A motor within the muzzle-head allows the barrel-assembly to
be flexible for trackability without necessitating rotation that
would result in excessive twisting. The turret-motor also provides
quick and accurate rotation during automatic discharge, can used to
oscillate the muzzle-head, aiding passage, and when suitably wired,
can be used to warm the lumen. A motorized muzzle-head turret as
shown in FIGS. 38, 48, 49, 65, and 66 conmprises a turret-motor
within motor housing 61 containing motor rotor 60 within motor
stator 62, and a motorized muzzle-head multibarrel turret rotary
joint 58, wherein motor housing 61 encloses motor stator 62 and
rotor 60.
[2935] Switching recovery electromagnets 65 toward nose 64 of
muzzle-head 70 between thermal ablative or angioplasty and miniball
recovery functions and/or turret-motor within motor housing 61
between thermal ablative or angioplasty and rotary positioning
functions is accomplished at the switch used to toggle between and
thus select the function desired, the circuit of the function not
selected being disconnected and thus disabled. One advantage in
mounting the muzzle-head in a motorized turret is that remotely
controllable, it is no longer necessary to rotate the entire
barrel-assembly merely to rotate the muzzle-head, and this allows
the use of more pliant materials in the barrel-assembly, so that
trackability is attainable and maneuverability ceases to pose a
significant risk of stretching injury.
[2936] Another advantage is that rotation of the muzzle-head allows
combining the use of barrel-blanked clips with rotation making it
possible to treat each successive segment of a vessel
discriminately as to the circumferential placement of the implants
with no need to withdraw an inserted barrel-assembly and replace it
with another. If necessary, the muzzle-head, to include both port
and magnet assembly portions, is wetted with a lubricious material
to minimize resistance to rotation by the motor. Endothelial cling
and resistance to passage by seizure are readily remedied when the
barrel-assembly is endoluminal by ejecting a lubricant such as
specified below in the section entitled Endothelial Cling and
Seizure through the muzzle-ports, or if the barrel-assembly is so
equipped, through perforated or injection-head radial projection
unit tool-inserts.
[2937] Yet another benefit of the ability to rotate the muzzle-head
by means of a motorized turret is elimination of the need for a
variety of muzzle-heads having different numbers of muzzle-ports at
different angles. A monobarrel barrel-assembly that is unassisted,
that is, lacks a motorized pivot, or a multibarrel turret that
lacks a motorized turret, requires a turning or torque ratio
sufficient to rotate the port or ports to the potential target
angle most distant angularly from its starting position without
jamming during discharge. The section above on multibarrel radial
discharge barrel-assemblies pointed out that a four-way
muzzle-head, for example, demands to be rotated up to 22.5 degrees
in either direction to target any circumferential angle about the
lumen and its diametrically opposed two trap-extraction
electromagnets up to 90 degrees in either direction to target a
misplaced miniball implant for extraction, and this angle can be
significantly larger with a barrel-assembly having eccentric
barrels.
[2938] Since a means for recovering any loose or mispositioned
miniballs is imperative, the lesser turning angle cited of 45
degrees to rotate a four-way muzzle-head for discharge is
superfluous, an angle of rotation for the magnet assembly taking
priority. This demands corresponding pliancy through the combined
effect of the barrel tubing material and the length of the splay
chamber. When the barrel-assembly is rotatable by means of a
motorized rotary turret and any rotary magazine clips that reduce
the number of miniballs discharged at a time as necessary are
available, then any circumferential placement of miniballs up to
the caliber that the lumen diameter will permit is possible without
a significantly greater risk of intraluminal stretching injury or
the need to withdraw and replace a barrel-assembly of one
configuration in order to replace it with another
mid-procedure.
[2939] With muzzle-heads with eccentric ports, the angular
displacement of the muzzle-head is dependent upon the pliancy of
the barrel tubing and the slack available in the splay chamber. The
rolling resistance presented by increasing curvature as the ports
are approached must be compensated for by adjustment of the airgun
settings. Rotating the muzzle-head purely to reduce the exit
velocity is not considered practical, the motorized turret provided
to assist in accurately placing the miniballs into eccentric
lesions. This notwithstanding, the incorporation of a motorized
muzzle-head that can be rotated to any angle eliminates the need
for rotating the barrel-assembly, and this has the advantage of
allowing the barrel-assembly to be made of more pliant tubing
material.
[2940] FIGS. 38, 39,48, 49 65, and 66 show barrel-assemblies with
built in motors that allow the muzzle-head to be rotated. Such an
apparatus allows the muzzle-head to be torqued at the treatment
site without the need to rotate the barrel-catheter and irritate
the lumen wall throughout its length, thus at all points proximal
thereto, and do so without imposing the need for a barrel-catheter
wall thickness that adversely affects trackability. While the angle
of rotation is limited by the need to avoid an out of round
condition of the barrel-tube lumina as would jam, a multibarrel
barrel-assembly with diametrically placed exit-holes can implant
the ductus at any rotatonal angle. When numerous lesions are
situated at different angles about the length of the ductus lumen,
the complete elimination of a need to torque the barrel-assembly
significantly increases the speed of treatment and reduces the risk
of complications.
[2941] The applicability of a motorized muzzle-head is limited by
the diameter of the motor that can be achieved to generate the
torque essential to rotate the muzzle bit through an arc in either
direction of up to 44 degrees for the caliber of miniballs
appropriate for the vessel to be treated. When a two-way or
three-way muzzle-head with muzzle-ports at angles other than 90
degrees meets the procedural requirement so that withdrawal and
replacement of the barrel-assembly will be unnecessary, then these
are used. Otherwise, rather than to withdraw one barrel-assembly in
order to replace it with another, a four-way barrel-assembly is
used and torqued slightly to position the ports used by the rotary
magazine clip as necessary.
[2942] VII2d(3)(c). Muzzle-Head Servomotor (Turret-Motor)
Desiderata
[2943] As indicated in the preceding section entitled Turret-motor
Operational Modes, the turret-motor must provide three modes of
operation--heating, oscillation, and positional control. In a
minimally capable barrel-assembly, these functions are selected and
adjusted using selector switches mounted on the airgun enclosure
and connected to the airgun power supply and the motor controller
and/or amplifier (drive), which controls both the transluminal and
rotatory position of the muzzle-head. In an ablation or an ablation
and angioplasty-capable barrel-assembly, heating and oscillation
must be controllable independently of an airgun. For freedom of
movement, tethering by a cable or cord is avoided through use of an
onboard control panel atop the power and control housing with the
battery pack inside thereof.
[2944] Airgun positional controls are maximized for use with
minimally capable barrel-assemblies and fully capable
barrel-assemblies while inserted in the airgun. Mounted on the
airgun enclosure, these pertain to use of the linear positioning
stage to set the rate of transluminal movement during nonmanual
thermoplasty or cryoplasty and also to control rotation of the
muzzle-head during implant discharge. However, when an ablation or
ablation and angioplasty-capable barrel-assembly is inserted in the
airgun, it is controlled in the same way as a minimally capable
barrel-assembly. By contrast, the need for free movement pertains
to manual use, during which connection to the airgun and controller
or servomotor amplifier is seldom if ever necessary.
[2945] That power is from a battery disallows conventional
solutions, such as producing oscillatory performance by detuning
the velocity loop in, or programming a set of oscillatory
(vibratory) frequency modes to be executed by, the servocontroller
without, for example, infrared transmission of the control signals.
More specifically, these modes of operation include 1. Rotation in
either direction as arc-limited according to the number and
twisting limits of the barrel-tubes, 2. Use of the motor windings
for heat generation to serve as a heating element for thermal
angioplasty (whether in coordination with like use of the recovery
electromagnets distal to the ejection head), and 3. Oscillation
useful for a. Assisting to free the muzzle-head should it cling to
or seize against the endothelium, or b. Imparting vibratory action
to the radial projection unit tool-inserts.
[2946] Unless matched to combination-form radial projection
catheters, minimally ablation and ablation and angioplasty-capable
barrel-assembly controls for heating the windings and to use any
radial projection units in the muzzle-head are mounted on the
airgun. When matched thus, these controls are duplicated on top of
the radial projection catheter power and control housing, which
further includes the controls for the components in the radial
projection catheter. Once an ablation or an ablation and
angioplasty-capable barrel-assembly has been inserted into the
airgun and discharge initiated, ablation or angioplasty should
seldom demand resumption.
[2947] Should the desirability for further angioplasty arise, the
control of angioplasty functions--individual or combined use of the
turret-motor and recovery electromagnets as heating elements for
thermal angioplasty and deployment and retraction of radial
projection unit tool-inserts--can still be controlled from the
control panel onboard the barrel-assembly as an independent
apparatus. However, combination-forms that additionally incorporate
a rotary burr or laser are more costly and less likely to be
adapted for conventional console-remote control, and more likely to
remain tethered prior to insertion into the airgun.
[2948] Unlike the linear positioning table or stage used to insert
and retract the barrel-assembly in submanipulable millimetric
increments as described below, which are available from many
manufacturers incorporating several different techniques,
turret-motors must be custom made to afford adequacy of
through-bore internal diameter within the severely constrained and
isolation of the magnetic fields within the motor from
implants.
[2949] Older technology brushed through-bore torque motors of
outrunner configuration are not preferred as incorporating a wound
armature or rotor at the center and permanent magnet stator in
surrounding relation thereto, which allows a through-bore of large
diameter but encircles the windings amid the surrounding permanent
magnets; the wound armature in a brushed motor of conventional or
inrunner configuration is the rotor and in a brushless
(electrically commutated) three-phase synchronous motor, the wound
stator, the rotor being the field assembly. Direct drive brushless
ring synchronous torque motors of inrunner configuration with a
proportionally large through-bore are made in conventional sizes by
Etel Incorporated, Motiers, Switzerland, for example.
[2950] For complete independence from the airgun, ablation and
ablation and angioplasty-capable barrel-assemblies have an inmate
polyphase controller and drive microcircuit. When this is not
possible, a controller and-amplifier is provided in the airgun
enclosure and connected to the barrel-assembly by a light cord. The
brushless type torque motor with windings peripheral rather than
encircled at the center is inherently better suited to the present
application than is the brushed or mechanically commutated type in
several key respects. Significantly increased power density, or
power-to-size ratio, supports the extreme miniaturization
essential, brushless operation provides much more precise and
uniform control at low speed, and the peripheral location of the
windings, if inadvertently, confers additional utility in allowing
circumscribed areas at the surface of the muzzle-head
(heat-windows) to be used for thermal angioplasty.
[2951] While in industrial applications the generation of heat
peripherally is beneficial for dissipating the heat, here the
reverse is true, the peripheral generation of heat used to
advantage. As described below, a prepositioned or inserted rapid
cooling catheter is introduced through the barrel-assembly to the
muzzle-head to return the ablating surface to body temperature.
Since positional use of the turret-motor is too intermittent to
generate any significant heat and the motor is never used
positionally and as a heating element at the same time, heat build
up does not limit torque output. Sine wave driven brushless direct
current (permanent magnet alternating current) through-bore torque
motors have windings that encircle the permanent magnet rotor
providing more direct transfer of heat through a heat-window
(addressed below).
[2952] Such motors further distance the rotor magnets from the
implants, adding a measure of protection against disruption due to
magnetic leakage despite the closed magnetic circuit of the
housing. Such a motor is able to provide a bore that is large
enough to provide a gas pressure relief path (addressed above) and
the passage of barrel-tubes. The small external diameter of the
motor necessitates maximum torque for the size, dictating the use
of a direct current (permanent magnet alternating current), motor,
which for reasons already stated, is made long relative to width.
The turret-servomotor is preferably a three-phase brushless direct
current, direct-drive (transmissionless, gearless) limited angle
through-bore torque motor or `torquer` with high axial, radial, and
torsional stiffness, and high stall torque (stand-still torque;
hold-fast torque) that develops its highest torque at low
speed.
[2953] Although the high lubricity and nonthrombogenic outer
surface of the muzzle-head keep resistance to turning of the
muzzle-head by contact with the lumen wall to a minimum, high stall
torque is imperative for the muzzle-head to rotate together with
the barrel-catheter and maintain ca onsistent rotary angular
setting whenever the operator hand torques (rotates) the
barrel-assembly. The closed-loop feedback signal is generated by
three digital Hall-effect commutation sensors that indicate the
instantaneous position of the rotor. A once-per-revolution index
sensor indicates the reference angle (home angle, home location,
rotational reference datum).
[2954] Alternatively, some control drive differentials or
comparators require position and velocity feedback from a coaxially
mounted resolver (analog) or optical encoder (digital), or a
potentiometer. To generate sufficient torque in a motor that the
portions of the arterial system most often demanding treatment can
limit to 2.5 millimeters in outer diameter, the motor stator is
wound with silver wire and the rotor and stator are made
proportionally longer, (i.e., greater in axial length) relative to
diameter, generally in the ratio of 5:1, such as 2.5 mm in diameter
and 12.5 mm in length.
[2955] Such is unconventional in torquer motors, which are
ordinarily `pancake`-configured. Thermal ablation and ablation and
angioplasty-capable muzzle-heads necessitate thermal insulation
about the heat-window or windows which, consisting of outer
coatings of silicon aerogel and polytetrafluoroethylene, for
example, present minimal thickness to limit even more severely the
diameter of the muzzle-head and therewith gauge of the vessel that
may be treated.
[2956] To achieve contact all around the muzzle-head without
stretching the lumen wall serves to assist in maintaining direct
thermal window-lumen wall contact for thermal angioplasty that uses
the turret-motor as the heating element while reducing the risk of
thrombogenesis due to interposed blood and avoid 1. Discharge
through intervening lumen contents allowing more equal impact force
among miniballs discharged at different radii as applicable, 2.
Compressing the media or the equivalent, making subadventitial
placement difficult if not impossible, and 3. Stretching injury.
Closed-loop control of the turret-motor is not intrinsically
necessary but arises by default in that alternative through-bore
remote positioners or drivers other than direct-current motors,
such as torque synchros and stepper motors, have drilled shafts,
which are unable to provide a through-bore of sufficient diameter
in motors of the millimetrically incremented outer diameters
required, generally 2.5 to 5 millimeters.
[2957] Additionally, through-bore direct-current torque motors are
familiar, whereas through-bore torque synchros and stepper motors
are novel, and would increase the design problems of
miniaturization even if alternative drivers could be made with
bores of sufficient diameter. Control of the turret-motor is
accordingly closed-loop, digital incremental, and point to point.
It being preferable for a given application to maintain contact
with the lumen wall circumferentially, the turret-motor, hence, the
barrel-assembly, is generally chosen on the basis of diameter as
well as the functions required. Since a condition of sliding
contact against the lumen wall entirely around the circumference
must vary, the load placed on the motor will vary.
[2958] Except when used as a heating element in barrel-assemblies
designed for thermal angioplasty as described in the section to
follow, the turret-motor is connected only intermittently in
positional use and therefore does not generate thrombogenic heat.
The direct-drive motor provides the backlash-free operation to
allow the servostiffness and bandwidth essential to achieve instant
accelerations, stops, and settling times. This suddenness of
operation affords the frictionless endothelial breakaway and quick
stops necessary to preclude tissue adhesion and stretching injury,
which the lubricity of the fluoropolymer coated muzzle-head
enhances.
[2959] For such point-to-point control, a feedback loop for
velocity is omitted, only displacement controlled. Additional
operation of the turret-motor (and tractive electromagnets) for
thermal angioplasty recommends quick heatability and dropping from
the less thrombogenic temperature of 90 degrees centigrade
(reference provided below). Elongation of the motor housing-lumen
wall interface thus allows sufficient torque in a motor of small
diameter making the device passable farther down the vascular tree
at the same time that it affords more surface contact area in
support of the angioplasty function.
[2960] In barrel-assemblies designed for thermal angioplasty,
elongation of the muzzle-head not only compensates for the
limitation imposed on motor power output by severe limitation in
diameter, but allows heat to be generated from three more
independently controllable sources of heat, as described below. In
barrel-assemblies equipped with radial projection units, a longer
muzzle-head not only compensates for the limitation imposed on
motor power output by severe limitation in diameter but makes
possible the use of longer longitudinally deployed side-brushes.
Direct drive through-bore torque motors with limited angle control
have been manufactured in conventional sizes and shapes by the
Kollmorgen company (through-bore pancake torquer models S200 and
S300 (not designations for controller-amplifiers), now a brand of
Danaher Motion, Inc.
[2961] With a four-way motorized muzzle-head, the maximum angle of
rotation required to direct the muzzle-ports is 44 degrees and the
tractive (trap) electromagnets 90 degrees in either direction. The
motor is made to fit a barrel-assembly of a certain diameter and
required range in rotational angle, at most, one full circle, which
allows aiming a radial discharge monobarrel in any direction and
provided the barrel-tube is made of sufficiently pliant material,
precludes rotation beyond the bore deformation tolerance before
discharge becomes impeded or is prevented. The distal termini of
the barrel-tubes, or muzzle-ports, can thus be remotely rotated
through an arc while endoluminal to discharge at an angle to either
side of a reference datum or 0 degree index at the center of the
overall working arc.
[2962] A turret-motor thus not only serves to overcome the need to
limit barrel-assembly flexibility to achieve the torqueability
required, but eliminates the need for muzzle-heads with eccentrtric
or radially asymmetrical muzzle-ports and does so without the
complexity involved in complete rotation. When the circumference or
the arcuate extent to either side of the center line of the lumen
wall in enfilade is not overextended, a noneccentric multiple
radial discharge barrel-assembly, that is, one with muzzle-ports
equidistant entirely about the circumference, typically four),
using fewer than all of the barrel-tubes, can be used for eccentric
lesions. To do this, the barrel-assembly is supplied miniballs from
a rotary magazine clip that lacks holes for the undesired
barrel-tubes.
[2963] The same approach is used to skirt or straddle a portion of
the vessel along the line of its attachment by connective tissue.
For use in an eccentric muzzle-head, the motor is restricted in
rotary angle to allow the muzzle-ports to be directed to any angle.
As shown in FIG. 85, a joystick is provided on the airgun control
panel to control the rotation and transluminal displacement of the
muzzle-head. For fine control over transluminal movement, the
barrel-assembly must be inserted into an airgun mounted on a linear
stage or connected to a separate linear stage, as addressed below
in the section entitled Ablation or ablation and
angioplasty-capable Barrel-assembly Control and Onboard Control
Panel.
[2964] Since the rate of linear stage travel must be determined by
the exposure time of the ablative or angioplasty action of the
muzzle-head as it passes over the lumen wall, and discharge is not
rate of travel sensitive, this rate, which likewise is controlled
by the commercial controller-drive (amplifier) unit, can be fixed
for any one type of angioplasty. Thus, whether the stage moves
intermittently during discharge apart from a thermal angioplasty,
for example, or continuously, as it must during an ablation whether
concurrent with discharge or not, this rate is unchanged. If used
for another process, such as a change from thermal to cryogenic
angioplasty, for example, then the rate of travel must be changed
accordingly.
[2965] VII2d(3)(d). Turret-Motor Operational Modes
[2966] In an ablation or an ablation and angioplasty-capable
barrel-assembly, the turret-motor has three separate and distinct
modes of operation--rotation, oscillation, and heating of the
windings in the muzzle-head. With the barrel-assembly inserted in
the airgun, any of these may further require control that is
coordinated with transluminal movement executed by the linear
postioning stage; control with the barrel-assembly in the airgun is
by the drive controller amplifier inmate within the airgun
enclosure, which has multiaxial and auxiliary function control
capability. The stand-alone capability required of an ablation or
an ablation and angioplasty-capable barrel-assembly when separated
from the airgun is addressed above in the section entitled
Muzzle-head Servomotor (Turret-motor) Desiderata.
[2967] VII2d(3)(d)(i). Turret-Motor Rotational Mode
[2968] The first is to rotate the muzzle-head, regardless of
whether the barrel-assembly is under manual or automated control at
the moment. Because ablation and angioplasty are primarily
performed by manipulating the barrel-assembly, it is best that the
barrel-assembly be self-contained and unconnected. The inmate
battery allows use of the turret-motor to rotate, oscillate or heat
the muzzle-head. Thus, except when some followup (slight
`touch-up`) thermal angioplasty is desired after the
barrel-assembly has already been inserted into the airgun,
angioplasty with the barrel-assembly is manual with the
barrel-assembly separate from (electrically and mechanically
independent from, not inserted into) the airgun.
[2969] Minimally ablation and ablation and angioplasty-capable
barrel-assemblies ablate or angioplasty to no greater extent than
is immediately preparatory to implantation. For reasons of economy,
minimally ablation and ablation and angioplasty-capable
barrel-assemblies omit an internal source of power and a power and
control housing. A matching combination-form radial projection
catheter for use with such a barrel-assembly can incorporate
additional controls for connection to the components within the
muzzle-head as well as supply these with power.
[2970] While in use to perform an ablation or an angioplasty,
minimally ablation and ablation and angioplasty-capable
barrel-assemblies are dependent upon insertion in the airgun for
connection to its power supply, hence, to positionally control the
turret-motor and deliver power to other angioplasty related
components. Otherwise, the proximal end is unconnected and freely
movable. Diseased portions of the ductus usually extending beyond
the margins of lesions as plainly apparent, transluminal precision
of the kind essential to implant miniballs is generally not so
critical that the ablation or angioplasty-capable barrel-assembly
cannot be transluminally advanced and retracted by hand. An onboard
electrically powered rail roller, for example, to advance and
retract the barrel-catheter during manual use of the
barrel-assembly as a separate apparatus would appear to offer
little if any advantage.
[2971] More precise positioning is always available by temporarily
inserting the barrel-assembly in the airgun to use its linear
positioning stage. Once a barrel-assembly that incorporates a
battery for independent power is inserted into the airgun to
initiate stenting, the independent capability of the
barrel-assembly can be made either to continue or be shut off
depending upon whether the microminiature electrical connectors
(jacks, female) within the airgun chamber into which the proximal
end of the barrel-assembly plugs or, if applicable, those within
the external cord, break battery contact upon engagement. with the
power supply within the airgun cabinet. Provided the battery
onboard the barrel-assembly has the storage capacity, switching is
provided so that the airgun components can draw power from the
battery.
[2972] VII2d(3)(d)(ii). Turret-Motor Oscillatory Mode
[2973] The second mode of operation is as a temperature controlled
heating element for thermal angioplasty whereby the turret-motor at
the rear of the muzzle-head at stall (and/or the tractive
electromagnets toward the front of the muzzle-head) are designed to
accept a surge amperage that quickly raises winding temperatures
from body temperature at 36.8.+-.0.7 degrees centigrade by 53
degrees centigrade or 98.2.+-.1.3 degrees Fahrenheit higher by 96
degrees Fahrenheit past the intervening thrombogenic range of
temperatures to 90 degrees centigrade or 194 degrees Fahrenheit.
This temperature has been determined optimal for thermal
angioplasty (Post et al. 1996, Thrombosis and Haemostasis
75(3):515-519), cited in the section below entitled Thermal
Conduction Windows (Heat-windows) and Insulation of the Muzzle-head
Body in Thermal Ablation and Thermal Ablation and Angioplasty
Minimally or Fully Capable (Independently Usable)
Barrel-assemblies.
[2974] Other temperatures will likely prove optimal for the
endoluminal ablation of other kinds of tissue, which, by
definition, will always be diseased, hence, sclerosed or malacotic
and deviating from the corresponding normal tissue in the
temperature required to ablate it. This temperature is considered
not only optimal for thermal angioplasty, but sufficient to destoy
the debris that passage of the muzzle-head could liberate, namely,
lipid, macrophages, T cells, proteoglycans, smooth muscle cells,
and collagen and calcified plaque particulates. Following this
initially steep rise in current, the current is reduced to maintain
a constant temperature of 90 degrees centigrade until no longer
needed.
[2975] To avoid the thrombogenic temperatures upon reverting to
body temperature, the muzzle-head is quickly cooled (defervesced)
by means of either a cold air gun or a cooling catheter as
addressed below in the section entitled Cooling Catheters
(Temperature-changing Catheters). In an ablation or an ablation and
angioplasty-capable barrel-assembly, to control the turret-motor
and recovery electromagnets as heating elements independently
requires that three heat servocontrol microcircuits be provided in
the hand-grip with angioplasty control panel at the proximal end.
With suitable thermal imaging equipment, momentarily heating the
turret-motor stator or one of the recovery electromagnet windings
can be used to assist in locating the muzzle-head.
[2976] Thermal ablation in ductus other than arteries is not
limited to 90 degrees centigrade, so that different temperature
settings are provided from 50 to 100 degrees centigrade in ten
increments of five degrees centigrade each. It being difficult to
incorporate temperature sensors into the muzzle-head, the
temperature control microcircuits use the equivalent current
respective of each heat-window as feedback. Variability in depth
and the heat transfer characteristics and thickness of different
tissues make emitted infrared radiation impractical for measuring
the temperature of even a single heat-window.
[2977] When used upon initial passage through an artery known or
suspected to harbor vulnerable plaque, the risk of rupture or the
dislodgement of debris at points about the muzzle-head where it
first makes contact with the surrounding lumen wall is minimized by
effectively subjecting the wall to a preemptive thermal
angioplasty. Such is not an angioplasty in the conventional sense,
but rather a continuous pass over the lumen wall whereby heat is
used to reduce the risk of rupture and embolism. For such an
artery, only a barrel-assembly with heatable front end may be used
and only with the windings of both recovery electromagnets
heated.
[2978] The precautionary (preemptive, nondiscretionary) angioplasty
with a minimally or fully angioplasty-capable barrel-assembly, in
which the recovery electromagnet windings are used as heating
elements, is used to preclude ruptures of vulnerable plaque by
contact with the muzzle-head at body temperature during
implantation discharge. A radial projection catheter can accomplish
the same action using tool-insert heaters. Just distal to the
barrel-ports, plaques are heated just in advance of discharge in
one operation, usually with a single pass, without the need to
withdraw and reenter.
[2979] By comparison, a balloon filled with a heated fluid must be
advanced incrementally and cannot carry the stent to be implanted.
Neointimal hyperplasia and restenosis is suppressed by implanting
miniballs or stays coated with antiproliferative medication, such
as paclitaxel or sirolimus, (gamma-) irradiating seeds, or
antiproliferative medication-coated seeds. Concerns that the heat
pretreatment will lead to intimal hyperplasia and stenosis in
portions of the artery not to be stented can also be reduced by
means of a prewithdrawal cryoplasty.
[2980] While not dependent upon an operative mode of the
turret-motor, other temperature adjusting means which are usable as
attachments to barrel-assemblies are closely related to this mode
of operation and are therefore coherently introduced at this point.
A cryogenic angioplasty, or cryoplasty (or a thermal ablation or
angioplasty for that matter) can be accomplished by attaching a
vortex tube cold air gun to the proximal end of the
barrel-assembly. Means for accomplishing a cryogenic angioplasty
preparatory to implantation are also provided. The incorporation of
cryplasty capability into barrel-assemblies is addressed below in
the section entitled Minimally Thermal Ablation or
Angioplasty-capable Barrel-assemblies.
[2981] Some researchers suggest that at least over the short term,
cryoplasty reduces restenosis compared to conventional angioplasty
(see, for example, Davies, M. G. and Anaya-Ayala, J. E. 2013.
Endovascular Techniques in Limb Salvage: Cutting, Cryo, Brachy, and
Drug-eluting Balloons," Methodist Debakey Cardiovascular Journal
9(2):69-72; Diaz, M. L., Urtasun, F., Barberena, J., Aranzadi, C.,
Guillen-Grima, F., and Bilbao, J. I. 2011. "Cryoplasty Versus
Conventional Angioplasty in Femoropopliteal Arterial
Recanalization: 3-year Analysis of Reintervention-free Survival by
Treatment Received," Cardiovascular and Interventional Radiology
34(5):911-917; Lyden, S. P. 2006. "Indications and Results with
Cryoplasty in the Treatment of Infrainguinal Arterial Occlusive
Disease," Vascular 14(5):290-296; Samson, R. H., Showalter, D. P.,
Lepore, M. R. Jr., and Ames, S. 2006. "CryoPlasty Therapy of the
Superficial Femoral and Popliteal Arteries: A Single Center
Experience," Vascular and Endovascular Surgery 40(6):446-450;
Laird, J. R., Biamino, G., McNamara, T., Scheinert, D., Zetterlund,
P., Moen, E., Joye J D. 2006. "Cryoplasty for the Treatment of
Femoropopliteal Arterial Disease: Extended Follow-up Results,"
Journal of Endovascular Therapy 13 Supplement 2:1152-1159; Laird,
J., Michael, R. J., Biamino G., McNamara, T., Scheinert, D.,
Zetterlund, P., Moen, E., and Joye, J, D. 2005. "Cryoplasty for the
Treatment of Femoropopliteal Arterial Disease: Results of a
Prospective, Multicenter Registry," Journal of Vascular and
Interventional Radiology 16(8):1067-1073; Lyden, S. P. 2006.
"Indications and Results with Cryoplasty in the Treatment of
Infrainguinal Arterial Occlusive Disease," Vascular 14(5):290-296;
Fava, M., Loyola, S., Polydorou, A., Papapavlou, P., Polydorou, A.,
Mendiz, O., and Joye, J. D. 2004. "Cryoplasty for Femoropopliteal
Arterial Disease: Late Angiographic Results of Initial Human
Experience," Journal of Vascular and Interventional Radiology
15(11):1239-1243).
[2982] At least in certain conditions, the efficacy of cryoplasty
has, however, been questioned if not contradicted (McCaslin, J. E.,
Andras, A., and Stansby, G. 2013. "Cryoplasty for Peripheral
Arterial Disease," Cochrane Database of Systematic Reviews
(8):CD005507; Shin, S. H., Baril, D. T., Chaer, R. A., Makaroun, M.
S., and Marone, L. K. 2013. "Cryoplasty Offers No Advantage Over
Standard Balloon Angioplasty for the Treatment of In-stent
Stenosis," Vascular 21(6):349-354; Spiliopoulos, S., Katsanos, K.,
Karnabatidis, D., Diamantopoulos, A., Kagadis, G. C., Christeas,
N., and Siablis, D. 2010. "Cryoplasty Versus Conventional Balloon
Angioplasty of the Femoropopliteal AAtery in Diabetic Patients:
Long-term Results from a Prospective Randomized Single-center
Controlled Trial," Cardiovascular and Interventional Radiology
33(5):929-938; Kessel, D. O. and Samson, R. H. 2008. "What is the
Evidence for the Efficacy of Cryoplasty?," Journal of
Cardiovascular Surgery (Turin, Italy) 49(2): 179-185;).
[2983] Current comparisons of available techniques for clearing
infrainquinal vessels will be found, for example, in Ramaiah, V.
2008. "Endovascular Infrainguinal Revascularization: Technical Tips
for Atherectomy Device Selection and Procedural Success," Seminars
in Vascular Surgery 21(1):41-49; Shafique, S., Nachreiner, R. D.,
Murphy, M. P., Cikrit, D. F., Sawchuk, A. P., and Dalsing, M. C.
2007. "Recanalization of Infrainguinal Vessels: Silverhawk, Laser,
and the Remote Superficial Femoral Artery Endarterectomy," Seminars
in Vascular Surgery 20(1):29-36. The risk of releasing debris in an
artery with either a minimally or fully capable barrel-assembly can
be reduced by deploying a damped plunger solenoid controlled
embolic trap filter, as described below in the section entitled
Trap Filter Deployment and Retrieval Mechanism.
[2984] For preventing the recurrence of restenosis that appears
following conventional treatment, cryoplasty appears no more
effective than conventional endovascular methods (Karthik, S.,
Tuite, D. J., Nicholson, A. A., Patel, J. V., Shaw, D. R.,
McPherson, S. J., and Kessel, D. O. 2007. "Cryoplasty for Arterial
Restenosis," European Journal of Vascular and Endovascular Surgery
33(1):40-43. While the winding of either recovery electromagnet is
separately heatable, when used upon initial introduction and
transluminal passage through an artery known or suspected to harbor
vulnerable plaque, the windings of both recovery electromagnets are
used to generate heat. Thus, in both minimally and fully ablation
or ablation and angioplasty-capable barrel-assemblies, a
heat-window fully encircles the recovery electromagnets as to
extend over the distal (front) end or nose of the muzzle-head for
heating the surrounding wall of the lumen.
[2985] Portions of the nose occupied by the distal embolic
protective trap-filter and a laser or atherectomy burr if installed
are omitted. Another heat-window can fully encircle the
turret-motor. Preemptive thermoplasty during advancement (moving
distad) with or without discharge is with the nose window. When
discharge is performed during withdrawal, the turret-motor window
can be used continuously or intermittently preceding discharge.
During initial contact heating before switching to tractive use
during discharge, the windings of both electromagnets are used as
heating elements. For uniform coverage over the luminal
circumference, the recovery electromagnet or nose heat-window must
wrap entirely around the nose dome.
[2986] By contrast, during discretionary thermoplasty, either
winding can be used independently to concentrate the heat directed
toward an eccentric lesion. For applications that call for a more
circumscribed heating area at the nose, a semihemispherical or
slotted overlay is added to the nose, generally in the form of
pre-cut press apply tape. Similarly, plaque usually eccentric and
the turret-motor behind or proximal to the point where the
muzzle-head makes intial contact with the lumen wall, the
turret-motor heat-window can be reduced to an eccentric slit- or
slot-shape to allow the differential direction of heat. It can have
circumferentially delimited slits, slots, or an elongated
rectanglar heat-window for directing the heat over a certain level
and arc (direction).
[2987] These likewise need not be fixed, but can be applied as
cutout patterns in press apply tape. Since temperatures above and
below 90 degrees centigrade have been determined to be thrombogenic
(Post et al. 1996, Thrombosis and Haemostasis 75(3):515-519, cited
below under the section entitled Thermal Conduction Windows
(Heat-windows) and Insulation of the Muzzle-head Body in Minimally
or Fully Thermal Ablation and Thermal Ablation and
Angioplasty-capable (Independently Usable) Barrel-assemblies),
heat-windows, whether enveloping, as at the nose (nose-cap,
nose-dome), or circumferentially delimited (eccentric), as at the
turret-motor, must to the extent possible be temperature isolated
from the surrounding surface of the muzzle body.
[2988] This is accomplished by making the window of silver and thus
creating a considerable differential in thermal conductivity
between the heat-window and the regions bounding it. However, even
when the areas adjacent to the heat-windows represent zones along a
gradient of decreasing temperature, unless located beyond the level
to which the focus of heat is moved, these adjacent areas are
exposed to temperatures below 90 degrees centrigrade only
momentarily before exposed to the full 90 degree temperature over
the window. That is, as the muzzle-head passes over the wall of the
lumen, only the segments of the ductus distal and proximal to the
area to be treated will `see` temperatures between body temperature
and 90 degrees centigrade; treated areas `see` such temperatures
only while the heat-window is approaching and departing.
[2989] The use of service-catheters to inject substances into the
lumen wall is addressed below in the section entitled Preparation
of Service-catheters for Use as Transbarrel-assembly Hypotubes.
Another time that thrombogenic temperatures will occur is when the
recovery electromagnets toward the front (distal end) of the
muzzle-head are switched from the heating to the tractive mode upon
initiating discharge. At this time, the magnets, usually along with
the trap-filter, are kept on (energized) instead to intercept and
recover any miniballs that would otherwise pass downstream.
[2990] The interval during the return from 90 degrees centrigrade
back down to body temperature can be eliminated or minimized by
prepositioning a cooling catheter as addressed below in the section
entitled Cooling Catheters (Temperature-changing Catheters) in the
central canal or a spare barrel-tube (service-channel) as addressed
below under the sections entitled Muzzle-head Access through a
Service-channel without the Aid of and by Means of Inserting a
Service-catheter and Thermal Ablation or angioplasty- (Lumen Wall
Priming Searing- or Cautery-) capable Barrel-assemblies.
[2991] A service-catheter configured as a cooling catheter for
quickly returning the muzzle-head and the heat-window in particular
as well as the heat-treated tissue to body temperature is used to
conduct cooler if not chilled air generated by a vortex tube based
cold air gun, vaporization from a small, typically 12 to 20 gram
cartridge of liquified carbon (CO.sub.2) or nitrous oxide
(dinitrogen (mon)oxide), (actually N.sub.2O but usually designated
NO.sub.2) gas or high purity 1,1,1,2-tetrafluoroethane (R134a)
cryogen spray over the treatment site. The delivery of gas or cold
water, for example, down the service catheter or central canal must
be through a nozzle that affords a return path so that pressure
will not accumulate.
[2992] Due to the small gauge of the service catheter, this will
usually be a double-lumen hypotube with a tip that flush fits into
the proximal end of the service catheter. The relatively quick
changes in temperature made possible with `cooling` is essential
for targeting circumscribed tissue for ablation (destruction,
removal) and avoiding consequences of successive steps that differ
in essential range if not optimal temperature. For example, if the
muzzle-head remained above 50 degrees centigrade following its use
to perform an angioplasty at 90 degrees centigrade, any solid
protein solder coating on the miniballs used to make the
extraluminal stent immediately thereafter would be caused to melt
prematurely.
[2993] Making indentations in and texturing the surface of the
solder both provides more surface area for quicker heating of the
miniball or stay ferrous metal core initiating melting or
denaturation more quickly and allows the take up of additional
cyanoacrylate cement when used. By directing a stream of cold air
at the back side of the muzzle-assemblly nose-cap, the same
apparatus can be used to perform a precautionary angioplasty.
Unlike the delivery of heat to the nose, which can be generated
intrinsically within the barrel-assembly by heating the windings or
by connecting a source of hot gas such as a vortex tube to the
end-plate, cold air is delivered by a cooling catheter or by
connecting a source of cold gas to the end-plate.
[2994] Whether to conduct heat produced by means of a vortex tube
or cold produced by a vortex tube (cold air gun) or by a CO.sub.2
or NO.sub.2 cartridge connected at the back of the barrel-assembly,
the use of a cooling catheter is necessary only in
Barrel-assemblies which would otherwise release gas into the
bloodstream. This is avoided in an edge-discharge muzzle-head of
which the central canal is used to house only a trap-filter silo
with enclosed back at its distal end. A gas vaporization cold
generating apparatus is described by Sellinger, M. S. and Currie,
R. B. 1971. "Cryogenic Biological Apparatus," U.S. Pat. No.
3,630,203, incorporation into a barrel-assembly necessitating
miniaturization of the parts that course through the
barrel-assembly central canal.
[2995] The use of such portable cartridges, which are commonly used
in airguns to provide the propulsive force for propelling the
projectiles (CO.sub.2) and in aerosol cans to dispense whipped
cream (NO.sub.2) for example, allows the cryogenic gas to be
carried on-board the ablation or ablation and angioplasty-capable
barrel-assembly, which thus remains free of a hose that would be
needed for connection to a separate supply tank. While temperature
inconstant over time and limited in charge and thus duration, such
a free-standing flash expansion vaporization chilling means would
rarely fail to meet the present needs. A discharged cartridge can
be replaced with a charged one, but where constancy of temperature
without interruption is desired, a vortex tube-based cold air gun,
which necessitates connection to the end-plate at the back of the
barrel-assembly by a small supply line or hose to a tank (cylinder,
canister) of compressed air, is used (addressed below).
[2996] Vortex tubes can maintain temperature constancy to within
one degree Fahrenheit using either the cold or hot air output.
Connection by a small hose at the back (proximal end) of the
barrel-assembly to a highly pliant hose leading to a supply of air
is not as hindering as would be the need to manipulate an ablation
or ablation and angioplasty-capable barrel-assembly that is
relatively inflexible and inserted into the airgun. Both because it
is not connected to function thus and is contained within the
airgun cabinet necessitating connection to the barrel-assembly
through a supply line, the cartridge used to power the airgun
(i.e., to provide the propulsive gas used to expel the miniball
implants) is not also used cryogenically.
[2997] Another reason for prepositioning a cooling catheter in the
muzzle-head is to cool the push type plunger solenoid in the nose
of the muzzle-head that is used to deploy a distal embolic
protective trap-filter when optimal materials notwithstanding, the
duty cycle with consequent buildup of heat would damage the
solenoid. Heat sinked, and through use of the cooling catheter, the
heat liberated by the solenoid is constrained to 90 degrees
centigrade, any thermal thrombogenic effect thereby averted when
used in the vascular tree. The ability to deliver cold air,
typically at -10 degrees centigrade (14 degrees Fahrenheit),
through a cooling catheter, allows the quick return to body
temperature of the electromagnet and turret-motor coils when used
for thermal angioplasty, and of the solenoid coil when energized to
deploy the trap-filter.
[2998] The cooling catheter is closed off at its distal terminus,
and the central canal and barrel-tubes are perforated to allow gas
contained within the barrel-assembly to be internally recirculated.
Gas is thus prevented from entry into the bloodstream, and the
cryogenic gas is quickly returned to body temperature. The
barrel-assemblies described herein are neither configured nor
intended to be capable of cryogenic angioplasty through the
incorporation of a cryoplasty balloon. Such balloons accomplish
angioplasty when expanded in apposition to the surrounding wall of
the lumen and left in place for 20 seconds at -10 degrees
centigrade.
[2999] While such a balloon could be deployed through the center of
the nose from the otherwise unoccupied central canal of an
edge-discharge muzzle-head as addressed below, a process that
required advancement of the balloon in increments of alternate
inflation and deflation would take too much time. A cryogenic
approach therefore directs nitrous oxide vaporized from a small
cartridge of nitrous or carbon dioxide temporarily attached at the
back (behind the end-plate) of the barrel-assembly while still
detached from the airgun toward the internal or back side of an
efficiently temperature conducting nose-cap window that is the same
as used as the heat-window (addressed below). The barrel-assembly
can then be slowly and continuously advanced or withdrawn without
the need to alternately deploy and stow a cryogenic balloon
incrementally.
[3000] Thus, in a precautionary angioplasty whereby the muzzle-head
is slowly moved over the wall of a lumen suspected or known to
harbor vulnerable plaque rather than directed at specific lesions,
the operator must arrive at a clinical judgment as to whether the
somewhat greater speed of using heat and reduced susceptibility of
extraluminal stenting to intimal hyperplasia outweighs the relative
freedom from consequent intimal hyperplasia of using cold or
performing a cryoplasty instead. The outlet temperature of a vortex
tube-based cold air gun is typically 70 degrees Fahrenheit lower
than the inlet temperature, so that supplied with compressed air at
75 degrees Fahrenheit, for example, a vortex tube-based cold air
gun can deliver air at 5 degrees Fahrenheit.
[3001] Absent an airgun, a barrel-assembly can serve as a single or
multiple channel guide-catheter for the aspiration of soft plaque,
the retrieval of tissue for analysis from along the inner surface
of the ductus, the delivery of medication whether in the form of a
liquid, powder, or gas, and/or to chill or heat highly
circumscribed areas along the internal surface of the ductus or use
a `cooling` catheter to rapidly adjust the temperature of the
muzzle-head. When used for the delivery of implants as well, the
barrel-assembly allows the introducer sheath to be entered and
withdrawn through but once for angioplasty, stenting, and the
passage of smaller catheters for such other purposes thus
minimizing irritation to the entry wound.
[3002] Unless a procedure will be completed in too little time for
the inlet temperature to change, merely to prerefrigerate or
preheat a canister of air or another suitable gas which is then
allowed to gradually return to the ambient temperature in the
operating room is not recommended, alternative means of providing
gas of constant temperature available. Placing the compressed gas
cylinder within a refrigeration or heating mantle or enclosure can
be used separately or with a vortex tube to achieve colder
temperatures. However, the cylinder must be close to the
barrel-assembly end-plate, since moving through a long supply line
will similarly allow gradual change to room temperature.
[3003] Thus, except occasionally for connection to a cold air gun,
all ablation or ablation and angioplasty-capable barrel-assemblies,
to include minimally thermal angioplasty (lumen wall priming
searing or cautery-) capable barrel-assemblies and fully ablation
or ablation and angioplasty (lumen wall priming searing or
cautery-) capable barrel-assemblies, are used separately and
independently of an airgun and inserted into the airgun only
afterwards to initiate stent-implantation. Left connected
throughout the angioplasty would seldom if ever impede the freedom
of transluminal movement due to tethering but rather due to the
relative immobility of the airgun even with the linear positional
stage used to advance and withdraw the barrel-assembly over
relatively small distances.
[3004] Small in gauge and pliant, the cold air supply line can be
left connected until the barrel-assembly must be inserted into the
airgun to commence stent implantation. A minimally ablation or
ablation and angioplasty-capable barrel-assembly need be no more
ablation or angioplasty capable than is necessary to preclude
ruptures and destroy the debris underlying the fibrous cap of the
atheromatous lesion or lesions through a preliminary preemptive
searing of the lumen wall prior to commencing with ballistic
implantation. However, even this level of function requires the
accommodation of a cooling catheter or line from a cooling cylinder
or CO.sub.2 cartridge, for example, to quickly return the heated
distal end, electromagnet heat-window, or nose heat-window back
down to body temperature.
[3005] Insertion into an airgun will always follow and require but
the quickly accomplished disconnection of the cooling catheter
supply line. A fully ablation or ablation and angioplasty-capable
barrel-assembly is all the more required to accommodate such a
line, because its use to perform an ablation or an angioplasty may
not be followed by stenting that uses the barrel-assembly. That is,
a fully ablation or ablation and angioplasty-capable
barrel-assembly can be used exclusively for transluminal ablation,
atherectomy, or angioplasty without ever having its other function
as a means for effecting implantation invoked.
[3006] As barrel-assemblies are not limited to use in the arterial
system, and these heating and chilling features can be used for
thermal (but not cryogenic) ablation in other type ductus,
barrel-assemblies other than minimally ablation or ablation and
angioplasty-capable contain controls to allow the selection of
temperatures (winding currents) other than 90 degrees centigrade,
usually from 50 to 100 degrees centrigrade in ten increments of
five degrees. With either type of barrel-assembly, as long as the
connection of the line used to convey cold or hot air or gas is at
the proximal end, that is, mounted to the end-plate, the line will
obstruct insertion into the airgun barrel necessitating that it be
disconnected ending its usability.
[3007] However, depending upon the type ductus to be treated, even
when other lines fed to a fully ablation or ablation and
angioplasty-capable barrel-assembly, such as a rotary atherectomy
burr or laser cable, must be disconnected to allow insertion into
the airgun, it can be of distinct advantage that access to chilled
and heated air or gas remain uninterrupted when the proximal end is
inserted into the airgun to initiate ballistic implantation.
Whether both the cold and hot gas are obtained from a cold air gun,
or the cold gas from carbon dioxide or nitrous oxide cylinder,
tank, or cartridge, such as is used to power an airgun (powerlet,
pistolet), and the hot gas from a separate source, such as a cold
air gun, continuity of access makes it possible to briefly chill
(not freeze) the tissue to be implanted.
[3008] Chilled tissue will be less mobile and chemically active.
Chilling the luminal wall during discharge effectively hardens the
target tissue, making higher velocity discharge possible than could
be employed at body temperature. Thus, in order to make any given
barrel-assembly as widely applicable to different type ductus as
possible, the ability to quickly change the temperature of the
target tissue during discharge is of value. Chilling becomes
especially significant if the momentum of the miniball as
discharged cannot be made sufficiently small to avoid perforation.
Although miniball velocity must be high enough to achieve
relatively clean puncture and penetration under any circumstances,
reducing the mobility of the target tissue further reduces
microtear injury and the risk of perforation.
[3009] The reduction in mobility of the tissue can also allow
improvement in aiming precision and the ability to achieve the
desired trajectory through, and depth of penetration into, the
luminal wall. By retarding chemical activity, cryogenic ballistic
implantation can also lessen the severity of sequelae, to include
inflammation. Similarly, in the use of a stay insertion tool as
addressed below in the section entitled Stay Insertion Tools,
chilling can be used to achieve greater precision in placing the
stays at the depth into the ductus wall desired whether medial or
supramedial. Whether supplied to a barrel-catheter or a stay
insertion hand tool, the use of a cold air gun has the advantage
that warming to follow the chilling is obtained by switching from
the cold to the hot air outlet of one and the same source
mechanism.
[3010] One and the same open-ended cooling catheter or stay
insertion tool line can be switched or transferred from a. A
suction pump to the b. Cold or c. Hot outlet of a vortex tube, d. A
compressed gas cartridge, or e. A tank containing adhesive delivery
line flushing solvent or f. Distilled water. For the foregoing
reasons, it is beneficial to provide a side access entry portal or
side-socket in a barrel-assembly through which a cooling catheter
or cold air gun output supply line in the form of a narrow hose or
tube can be advanced down a (servicing) barrel-tube or the central
canal of an edge-discharge barrel-assembly and a side-socket for
connecting the hose.
[3011] Since the vortex tube cold air gun emits hot air at the
opposite outlet, it can be used as an alternate source of heat for
thermal angioplasty as well. With the qualification that the volume
of air delivered by the vortex `cold` air gun diminishes in
proportion to the extremity of the temperature demanded, the
overall range of temperatures that such a gun can deliver is
dependent upon the temperature of the air supplied from the
compressed air cylinder (tank, canister) and to a much lesser
extent, the ambient temperature, but generally ranges from 15 to
250 degrees Fahrenheit, which range encompasses the temperatures
used for ablation and angioplasty whether cryogenic or thermal. The
degree of capability is also based upon whether each such heating
element is independently controllable by a separate temperature
servocontrol microcircuit in the hand-grip.
[3012] A more basic embodiment is distinguished from one of greater
capability in that the latter also incorporates a positional
servocontrol microcircuit in the hand-grip, positional use of the
turret-motor while disconnected from the airgun limited to the
support of angioplasty. Use of the turret-motor both as a heating
element and mover necessitates the coordinated control of winding
temperature. Cooling back down to body temperature past the
thrombogenic range is accelerated by means of passing a special
cooling catheter or rapid cooling catheter down the barrel-assembly
or spare adjacent barrel-tube (service-channel) as addressed below
under the sections entitled Muzzle-head Access through a
Service-channel without the Aid of and by Means of Inserting a
Service-catheter and Thermal Ablation or angioplasty- (Lumen Wall
Priming Searing- or Cautery-) capable Barrel-assemblies to the
turret-motor and/or electromagnets, as will be described.
[3013] VII2d(3)(d)(iii). Turret-Motor Heating Mode
[3014] The third mode of operation is oscillatory, obtained either
by detuning the turret-motor drive velocity loop, in which case the
oscillation is random, or if the movement is to be contolled, then
by programming the reciprocal motion according to sinusoidal
profiles which can be selected, s-ramping used to obtain smooth
performance if desired. While in most instances, one or two
frequencies and arcuate strokes (excursion) to either side are
satisfactory, some radial projection unit tool brush type insert
tips that function efficiently at a certain frequency or stoke may
require more settings. The oscillatory mode is used mainly to aid
in maneuvering the barrel-assembly or produce a vibratory action at
the treatment site, such as to swab, brush, or abrade the lumen
wall by increasing the frequency and/or vigor (forcefulness) of
side-sweeping with radial projection unit tool-inserts.
[3015] While it has been devised for the maximum surface lubricity
(slipperiness, slickness), should the muzzle-head nevertheless
cling to the lumen wall, oscillatory movement can be used to free
the muzzle-head, usually following delivery of a lubricant through
a service-channel or to vibrate brush type radial projection unit
tool-inserts, or side-sweeping brushes (side-sweepers), but never
in an attempt to pass a tortuous stretch of a vessel, where such
action can result in stretching injury or even perforation. Fever
tends to reduce thrombogenicity and may be disregarded for the
present purpose (see, for example, Groza, P., Artino-R dulescu, M.,
Nicolescu, E., Munteanu, A., and Lungu, D. 1987. "Blood Coagulation
and Fibrinolysis in Hyperthermic Rats," Physiologic
24(4):213-220).
[3016] The use of silver wire achieves the maximum electrical and
thermal conductivity (transcalency, adiathermancy, athermancy) in
both the turret-motor and tractive electromagnets, which in
barrel-assemblies designed for thermal as well as mechanical
angioplasty, also serve as temperature-controlled heating elements.
High electrical conductivity equating to low resistance with less
heat generated for a given level of current, silver wire windings
require proportionally more current to be raised to 90 degrees
Celsius; however, in no instance should an electrically separate
outer coil of nichrome wire be needed as the heating element.
Consistent with the use of insulation in electrical motors and
magnets, the insulation must be effective electrically but
thermally conductive.
[3017] The subminiature dimensions of the turret-motor necessitate
that to achieve a reasonable service life, the winding varnish be
made as thick as space will allow (see, for example, Grise, W. R.
and Zargari, A. 1997. "Delamination and Cracking Failures in
High-voltage Stator Winding Coatings," Electrical Insulation
Conference and Electrical Manufacturing and Coil Winding Technology
Conference, 1997, Proceedings, 22-25 Sep. 1997, pages 835-839);
however, for ablation or angioplasty, the electrical insulation
should minimally interfere with thermal conductivity (see, for
example, Speer, D. R., Jr. 1997. "Thermal Conductivity Improvements
for Electric Motors," Electrical Insulation Conference and
Electrical Manufacturing and Coil Winding Technology Conference,
1997, Proceedings, 22-25 Sep. 1997, pages 723-725).
[3018] Finally, lesion removal and stenting in a single operation
is significantly augmented with the incorporation into the
barrel-assembly of conventionally independent means for the removal
of highly calcified plaque, to include a rotational atherectomy
burr or laser catheter. Provided the parameters appurtenant of the
action are closely determined and controlled, the miniballs
bioinert, and sterility achieved, the implantation by ballistic
means of ferromagnetic miniballs just inside the tunica adventitia,
subadventitially (perimedially), or medially is safe (for a
histological description of the tracheal adventitia, see Ohkimoto
K, Mouri M, Amatsu M, and Teraoka M. 1997, "Histological Study of
the Tracheal Adventitia, Perichondrium and Annular Ligament (in
Japanese with English abstract at
http://www.ncbi.nlm.nih.gov/pubmed/9423323), Nippon Jibiinkoka
Gakkai Kaiho (Japanese Journal of Otolaryngology)
100(11):1394-1400.
[3019] The oscillatory mode can be used to improve the speed and
ease of side-sweeper use. Imparting an oscillatory action to the
brushes allows material deposited on the lumen wall to be removed
with more thoroughly and efficiently. When only ablative or
angioplastic use is contemplated so that the barrel-assembly will
not be inserted into an airgun, that is, when the barrel-tubes can
be fouled, this sweeping or scraping action can be performed with
the distal end of the barrel-assembly inserted into a vacuum pump
to clear out debris as it is generated, the trap-filter available
for this purpose as well. When this procedure is preparatory to
discharge, any barrel-tubes used thus must be lined with a
barrel-tube lining, or service-catheter.
[3020] The oscillatory mode can be used with side-sweepers to
increase the sample yield for brush cytological biopsy, the
material vaccumed out through the barrel-tubes or
service-catheters. The oscillatory mode can also be used to more
evenly apply medication that is driven down through the
barrel-tubes by a syringe, bulb, or pump with or without the
subsequent use of the same or the concurrent use of other
barrel-tubes to vacuum away any excess. The concurrent use of one
or more barrel-tubes to deliver, while one or more other
barrel-tubes vacuum away or allow a path for the removal of lavage
fluid, in a manner similar to many nasal irrigation devices--which
may be used in support of one of the foregoing processes, such as
the retrieval of tissue for diagnosis, with or without the aid of
radial projection unit side-sweeper tool-inserts oscillated or
rotated with the turret-motor or longitudinally (transluminally)
reciprocated by hand or linear stage--is considered obvious.
[3021] Other than in a blood vessel, similar use of the
barrel-assembly allows the application of an agent, such as an
acid, for chemoablative therapy, flushing away of the agent with
water, for example, and aspiration of the wash water. The object in
such use is to prepare for stenting implantation without the need
to withdraw the barrel-assembly, which can instead be directly
inserted into the airgun. For that reason, even for the removal of
diseased tissue at the lumen surface and not to eliminate the
vessel as a whole, sclerotherapeutic methods of chemical ablation,
such as the transendoscopic injection of ethanol or acetic acid,
which involve a time-delay and almost always require more than a
single treatment, are not suitable for such application.
[3022] Broadly, an ablation or an ablation and angioplasty-capable
barrel-assembly will allow any transendoscopic procedure, to
include the passage of ultrasound or laser microsurgical
miniprobes, and the use of barrel-tube will bring the inserted
device to the lumen wall whereas the use of the central canal in a
combination form barrel-assembly will allow a straight ahead or
lumen axial access; however, a combination-form barrel-assembly
having an endoscope in the central canal or simpler barrel-assembly
with an endoscope lashed alongside it must be used or an
alternative means for viewing the process will be required.
[3023] VII2d(3)(e). Radial Discharge Barrel-Assembly Working
Arc
[3024] The working arc is the practical range of rotational
excursion of the muzzle-head to either side of the turret-motor set
point as limited by the deformation tolerance of the barrel-tubes
in use. The working arc is thus the arc through which the
turret-motor is limited in rotating its specific muzzle-head or the
distance to which the muzzle-port group can be rotated to either
side of its center as point of reference and thus the arc of the
lumen in enfilade, or the arc of the lumen circumference accessible
to discharge, within the beaten zone. Since unlike radial discharge
barrel-assemblies, a simple pipe-type muzzle-head does not a.
Conduct barrel-tubes internally in concentric relation that must
not be deformed (bent) at the curve preceding the muzzle-port to
the extent that jamming results so that its rotation must be
limited, or b.
[3025] Require remote rotation to either side of the center or
zero-point of a positional control system, it can be freely rotated
by hand, so that the concept of a working arc does not apply to
it.
[3026] As addressed in the section above entitled Simple Pipe Type
Barrel-assemblies, the flange component of the barrel-assembly to
airgun twist-to-lock connector is friction fitted to the end of the
airgun muzzle, allowing it to be rotated. In a multibarrel as
opposed to a single barrel barrel-assembly, rotation of the
barrel-assemblly at this connector must be done in coordination
with corresponding rotation of the rotary magazine clip. Otherwise,
the alignment between the clip holes and the barrel-tubes
respective of each is undone or each becomes aligned to the wrong
clip hole, resulting in the discharge of consecutive miniballs in
the wrong sequence where some may have consisted of medication and
others of ferromagnetic material, for example.
[3027] In addition to allowing rotation of the working arc,
insertion of the barrel-assembly once intraluminal, such as
following an intraluminal ablation does not, therefore, require
withdrawal and reentry or rotation of the barrel-assembly in the
lumen. The limited rotatability of the muzzle-head cannot be
overcome by any adjustment to the onboard components, such as by
redefining or electronically moving the setpoint at the numerical
position translator. The arcuate limit established by the twisting
limit imposed by the barrel-tubes, adjustment by this means will
only shift the setpoint so that a portion of the working arc that
would have remained accessible had the setpoint not been shifted is
removed from access.
[3028] A detent arm that projects from the rear rim of the
muzzle-head and stop-tab secured to by ringing (banding) about the
barrel-catheter prevents over-rotation of the turret-motor during
direct manual control, the incorporation of a circuit breaker or
warning signal for the purpose prevents overheating or burnout.
When the muzzle-ports are placed about the muzzle-head
equidistantly in radial symmetry, any port can be taken as the
reference index for rotation. However, since an eccentric
muzzle-head groups the muzzle-ports more closely about the
circumference, this center point or reference index for
turret-motor rotation is taken as aligned to the most central
muzzle-port in the group.
[3029] Using four or more muzzle-ports places every point about the
lumen circumference under the rotational arc of two muzzle-ports,
which would eliminate the need to rotate the airgun were discharge
limited to quadrant placement. The extent of muzzle-head rotation
by the turret-motor limited to prevent distortion of the
barrel-tubes as would interfere with discharge as addressed just
above in this section, an eccentric muzzle-head having exit ports
in closer proximity about the circumference is advantageously
employed when the turret-motor is used to index between adjacent
exit ports where each barrel-tube conveys a catheter directed
toward accomplishing a different treatment option, such as for one
to aspirate a tissue sample, the next to deliver a drying agent,
the next to eject medication, and so on, as addressed in the
section below entitled Rotation of Multibarrel-tube Muzzle-heads
Used as Multiple Purpose Guide-catheters.
[3030] In fact, by blanking rotary magazine clip holes, performing
one transluminal run, indexing the muzzle-head by the
circumferential distance from the first run desired, then reversing
direction in a second run, it is possible to lay down the implants
in any pattern; since a lesser degree of rotation will bring one or
another of the muzzle-ports to overlie or subtend any arc about the
muzzle-head, increasing the number of evenly spaced muzzle-ports
reduces the need to rotate the working arc. The use of rotary
magazine clips is described below. However, an eccentric
muzzle-head can gain the advantages of less complexity and greater
speed, can, for example, lay down several closely spaced rows in a
single run.
[3031] When it is difficult to ascertain whether a suitable
starting angle (working arc center; control set point) as
establishes the center of the working or treatment arc has been
achieved, preliminary discharge for effect allows this angle to be
determined, to reveal, for example, whether the correct two out of
four rotary magazine clip-holes properly received the load. Within
the working arc, the turret-motor provides finely adjusted rotation
essential to uniformly place implants at intervals to evenly
distribute the magnetic traction. While the muzzle-head must be
rotatable, the barrel-tubes are continuous from the airgun chamber
to the muzzle-ports and can be bent only so much before deformation
interferes with discharge.
[3032] Furthermore, for safety and to achieve precision fitting,
the components of the barrel-assembly are made unadjustable or
fixed in rotational alignment, a means for gross rotational
adjustment, that is, for rotating the assembly as a bodily whole is
necessary. This limits the extent to which the muzzle-head may be
rotated. With the proximal end of the barrel-assembly locked in
position within the airgun, no free proximal end as can be manually
rotated when a angioplasty capable barrel-assembly is used
independently before connection to the airgun is present. To make
eccentric barrel-assemblies with muzzle-port groups in different
quadrants, for example, with the unrotatable stop-and-lock
connection made is unacceptable, since with such working arc
limited muzzle-heads, to rotate the working would necessitate
removing the barrel-assembly arranged around one angle and
replacing it with another.
[3033] VII2d(3)(f). Rotation of Working Arc
[3034] To avoid such limitation, the airgun is mounted to afford an
additional degee of freedom, viz., the ability to rotate about the
longitudinal axis passing through the center of the
barrel-catheter, and therewith, rotate the working arc. Since the
connector shown as 47 in simple pipes and 75 in radial discharge
barrel-assemblies can be forcibly rotated by hand, this too can be
used as a rotary joint to change the arc of the working arc. As
shown in FIG. 83, rather than to rotate the barrel-catheter or
airgun barrel separately, the mounting used to allow the
barrel-catheter about the long axis through the airgun barrel
preferably consists of inverted U-shaped cradle swing or swivel
bracket 149 bent into heavy gauge strip steel stock by a brake. The
vertical side to side connecting segment or bridge portion of the
bracket is screwed down to the upper surface of the linear
positioning table 150.
[3035] Airgun 151 rests on and can be locked at any rotational
angle coaxial to the long axis of airgun barrel 152 in compression
or tightenable swing cradle bracket 149. The cradle allows
adjustability in the angle of rotation in the same way as the
elevation adjusting device of a spotlight, except that the
spotlight has tightening knobs at both sides while swing cradle
bracket 149 has only one tightening knob 154 at the rear. The front
component of the airgun enclosure-divided shaft that allows long
axis airgun barrel 152 coaxial rotation of airgun 151 consists of
airgun barrel 152 itself, while the rear portion consists of male
threaded short stud 153 with upward directed pointer, resistance or
spot-welded to the back of airgun cabinet 151.
[3036] A round scale with the rotational angle marked off in
degrees is affixed by means of an adhesive to the rear surface of
the rear arm of swing cradle bracket 149 in surrounding relation to
the stud hole. Airgun barrel 152 and stud 153 fit through airgun
barrel long axis-centered holes toward the upper ends of the front
and rear arms of cradle-bracket 149. Rear stud 153 having been
passed through the hole in the rear arm of cradle bracket 149, a
Belleville disk ring spring washer is placed over the stud,
centered in the angle scale and flush against the rear side of
cradle bracket 149. Rotating airgun 151 thus rotates the pointer
mounted on stud 153 over the scale, indicating the angle of
rotation of airgun 151. Tightening knurled knob threaded over stud
153 compresses together the arms of cradle bracket 149 against the
front and back of airgun 151 enclosure, fixing the airgun in
rotational angle.
[3037] When, as shown in FIG. 83, spaces separate the knurled knob
at the back and the front of airgun 151 enclosure from the swing
cradle bracket, tube spacers (spacer sleeves, spacer tubes) are
used to take up the intervals. The knob is tightened so that the
rotational angle of the airgun, which is stabilized in angle of
rotation by friction, can be adjusted by hand. At the front of the
airgun cabinet, the barrel passes through a hole that journals by
friction fit a ball bearing that holds the airgun barrel in
surrounding relation. The axis of rotation for this airgun
swing-type carriage mounting is thus coaxial with the airgun barrel
and therefore allows adjustment in the working arc. To measure and
render observable the extent of linear travel of the linear
positioning table, horizontal joint between the base and moving
platform of the linear positioning table 150 is calibrated in
millimeters. A failure to discharge will be evident and thus can be
distinguished externally, as discussed in the section below
entitled Modes of Failure.
[3038] Less desirably, the airgun discharge components
proper--CO.sub.2 or compressed air cylinder, valve body, chamber,
and barrel--can be separately mounted within the airgun cabinet for
rotation on a U-bracket mounted on a linear positioning table,
which then contained within the cabinet at the bottom, even when
made of transparent polycarbonate plastic with a hinged or
removable top that may be left open to allow access to allow
adjustment to the valve body slide as described below, is then more
likely to obscured from view by reflection. Such an arrangement
thus reduces the observable action of the linear positioning table,
of which the incremental moves, at both airgun barrel cabinet
portal and entry into the body, are minute and not readily
observable. Since this would make a malfunction less noticeable, it
is not preferred.
[3039] VII2d(3)(g). Control of Muzzle-Head Turret-Motor Angle
Within Working Arc
[3040] Due to the small size of the distances to separate the
implants, control over the positioning of the turret-motor to
adjust the muzzle-head rotational angle and airgun linear stage
mounting to adjust the transluminal displacement, cannot be left to
direct manual control. By contrast, transluminal positioning of the
muzzle-head for puposes other than discharge can generally be left
to direct manual control, or if necessary, connection to a linear
stage whether by insertion in an airgun mounted to one or an
independent stage. Instead, a numerical translator intervenes
between the operator and the movements of the turret-motor and
airgun table mounting. Such control is indirect and semiautomatic,
in that the operator sets knobs for the action to be accomplished,
and the controller and translator then execute the motion
commanded.
[3041] Closed-loop control of the subminiature dc through-bore
torque muzzle-head turret-motor is conventional, differing from
programmed numerical control only in real-time setting of the angle
by the operator. The same joystick is rotated clockwise or
counterclockwise to the angular displacement of the turret-motor
sought. When such point-to-point repositioning is to place the
muzzle-head for successive discharges of the airgun, the duration
at each intervening point need not be coordinated with miniball
transit time, because the pause between the increments is preset to
allow for the longest barrel length, typically 140 centimeters,
this length being a critical factor in setting the exit velocity
and provided with the apparatus. The output angle of the turret
motor can be controlled with any digital motion controller and
amplifier capable of driving a three phase brushless dc motor.
[3042] An exception pertains to the discharge of miniballs
concurrent with an ablation or an angioplasty by an ablation or an
ablation and angioplasty-capable barrel-assembly in the same pass.
This generally comes about because medication miniballs are used to
introduce medication concurrent with the traumatizing process. In
this situation, exposure time to the ablative action fixes the
uniform rate of travel at which the muzzle-head must move past the
lumen wall, to which the rate of miniball discharge must be
subordinated. Discharge at the airgun chamber is thus anticipatory
by an interval contingent upon the velocity of the miniballs and
overall length and uniform rate of transluminal travel of the
barrel-assembly, so that the miniballs may be sent from the chamber
well before the exit port reaches the target location or before the
preceding miniball has penetrated.
[3043] Numerous full-sized two-axis off-the-shelf or commercially
available controller-amplifiers are available for alternately
allowing the a. Manual control of muzzle-head declination and level
(depth of transluminal entry into the ductus) by means of a
joystick or b. Manual control of automatic pattern control of the
direct current turret-motor, the linear stage stepper motor, and
discharge by the airgun in a coordinated manner as an auxiliary
function much as the rotation of an interchangeable cutting tool
turret on an automatic milling machine. When the ductus treated has
been stabilized, as addressed below in the section entitled
Motional Stabilization of the Implant Insertion Site, discharge is
alleviated of the need to synchronize to intrinsic smooth muscle
function.
[3044] When, however, the operator has no difficulty in
anticipating the pulsation or contraction, stabilization of the
action with medication or mechanical means is dispensed with,
discharge synchronized to this action so that in an artery, for
example, muzzle-head positioning is accomplished between and
discharge during the diastoles. The airgun closed-loop
semiautomatic system is to the extent possible assembled from
commercially available components, to include a motor
controller-amplifier, such as a Danaher Motion, Inc. S200 drive or
comparable control apparatus from another manufacturer, such as
Fanuc Robotics, Tolomatic Axiom, Yaskawa Electric Corporation,
Parker Hannifin Corporation, Copley Controls Corporation, Baldor
Electric Company, ACS Motion Control, and several hundred other
companies, and controlled from the control panel mounted to the
airgun.
[3045] Many such controller-drivers can exercise coordinated
control over the turret-motor, linear stage, and discharge with the
barrel-assembly engaged in the airgun mounted on a linear stage.
The contoller and amplifier for an ablation or an ablation and
angioplasty-capable barrel-assembly with onboard control of the
turret-motor requires a miniaturized controller and amplifier as
indicated above in this section. To position the two diametrically
directed electromagnets to face along any given diameter,
rotatability of 90 degrees in either direction is required;
however, to aim a monobarrel at any angle about the lumen
circumference necessitates rotatability of 359 degrees. The
material and thickness of the barrel-tube, and the curve it
describes as it approaches the flush joint socket in the
ejection-head must allow this degree of rotation without distortion
to the bore as would retard or jam discharge.
[3046] When implantation discharge proceeds under motorized
control, positional efficiency and longer turret-motor life are
obtained by traversing the segment (length) of the ductus to be
treated from end to end, discharging at intervals, then, when
reaching the end of the `run,` rotating the muzzle-head before
reversing direction to place implants at an angle or angles other
than that or those implanted on the first `run.` That is, to
discharge, rotate the muzzle-head, discharge, then advance or
withdraw, discharge, rotate the muzzle-head, and so on, is not
preferred. The transluminal (longitudinal) movement on the first
`run` can be advancing or withdrawing. In more sophisticated use,
longitudinal and rotary movement of the muzzle-head can be
continuous throughout discharge, making possible implantation at
high speed.
[3047] Nevertheless, for simplicity and because fast operation
assumes the availability of imaging equipment that would instantly
reveal a problem, the muzzle-head is best kept stationary during
the interval that the miniballs traverse the barrel-tubes and enter
the wall of the ductus. The turret-motor control circuit includes a
circuit-breaker to prevent overload or burn-out. Excessive
resistance to rotation arising withing the mechanism or in the
relation of the mechanism to the lumen wall is thus truncated. For
example, resistance to the action of radial projection unit
side-sweeping tool-inserts when present would typically be
presented by plaque that was calcified outside the area cleared by
atherectomy. Exceeding the torque limit value set for any reason
would shut down the turret-motor averting dissection.
[3048] The distal end of the barrel-catheter is clamped within the
collar at the proximal end of the through-bore turret-motor
housing. In a radial discharge monobarrel, the barrel-catheter and
singular barrel-tube are one and the same, and the distal curved
segment of the barrel-tube is journaled within the rotor, which
accordingly serves as a rotary joint. In a multiple barrel
barrel-assembly, such axial rotation is not possible, so the neck
of the spindle is journaled in the rotor. A motorized muzzle-head
eliminating the need for a tighter turning ratio or turning torque
in the barrel-assembly, more pliant materials can be used for the
barrel-catheter, enhancing steerability and eliminating the
possible if infrequent need for the aid of a hand-held external
electromagnet.
[3049] The resistance to twisting more pliant barrel-tubes for the
length of these in the splay chamber is less than with a stiffer
tube material such as polytetrafluoroethylene. Dots of more
brightly radiopaque contrast marker, such as Danfoss Tantalum
Technologies Danfoss Coating.RTM. just beneath each muzzle-port,
assists in positioning the muzzle-head. The greater pliancy of
catheter tubing afforded by a motorized muzzle-head increases the
potential for using conventional fixed shape guide-catheters as
barrel-catheters. Vascular bends and angles of intersection or
branching proximal to the lesion that are too acute to allow the
smallest diameter barrel-assembly acceptable for stenting a given
ductus to pass necessitate open exposure.
[3050] When the barrel-assembly is connected to a modified
off-the-shelf hand airgun, power is provided to the motor from a
remote power supply with connector mounted beneath the pistol grip.
The placement of the power supply is different in modified and
dedicated airguns as will be described under the section on
airguns. Two small single pole single throw push button type
switches are mounted to the pistol grip just above and beneath the
ball of the thumb, so that slightly raising the thumb and
depressing the upper allows the muzzle-head to be gradually and
controllably rotated up to the rotational displacement necessary
clockwise and depressing the lower switch allows rotation
counterclockwise without the need to reposition or look at the
airgun.
[3051] VII2d(3)(h). Factors that Affect Muzzle-Head Nosing Length
or Reach, Steerability, and Trackability
[3052] Whereas elongation in the nose or elements of the
muzzle-head forward (distal, anterior) of the muzzle-ports reduces
the forward reach or depth of access for discharging implants in a
lumen of given diameter, elongation proximal to the muzzle-port or
ports does not. Increasing the diameter, however, instantly limits
passability down the vascular tree to deny access to smaller
vessels. The incorporation into the muzzle-head of electrical
radial projection units as addressed below in the section entitled
Radial Projection Units, is limited in longitudinal extent by the
resultant reduction in steerability.
[3053] A sufficient number of electrically operated radial
projection units can be incorporated into the muzzle-head to allow
the use of electrical/fluid system-neutral or self-contained
spring-release syringe tool-inserts that can release a lubricant to
aid passage or the use of side cutting tool-inserts to debulk
obstructive tissue at the sides, and a nose heat-window as
addressed below in the section entitled Thermal Conduction Windows
(Heat-windows) and Insulation of the Muzzle-head Body in Thermal
Ablation or Thermal Angioplasty Minimally or Fully (Independently
Usable) Capable Barrel-assemblies can make it possible to pass
through a heavily occluded ductus.
[3054] When the barrel-assembly incorporates radial projection
units with side-shaving razor edged or sweeping ablation by
abrasion brush tool-inserts engaged, the increased torque required
is achieved by enlarging the motor windings longitudinally rather
than diametrically. Fluid operated tool-inserts, which are capable
of intermittent or continuous irrigation or aspiration, for
example, require a fluid line that would demand an increase in the
diameter of the muzzle-head. When the release of a fluid and its
aspiration must be concurrent rather than alternating, two fluid
lines are required. Untenable dimensions of the muzzle-head for use
in a given type ductus are contained by relegating any that demand
excessive longitudinal extent or breadth to a separate device that
can be slid over the barrel-assembly after having been passed to
treatment site.
[3055] Thus, the muzzle-head in an ablation or an ablation and
angioplasty-capable barrel-assembly typically has only so many
electrically operated radial projection units as necessary and is
in effect one of a two part apparatus of which the outer can be
added or withdrawn at any time. A loss in forward reach
notwithstanding, embodiments that necessitate extension of the nose
to house a trap-filter are extended when radial projection unit
side-sweeping type tool-inserts are installed. As discussed above
under the section entitled Concept of the Extraluminal Stent and
the Means for Its Placement, the benefit in distal embolic
protection filters remaining controversial, embodiments without
side-sweepers installed are provided without a distal embolic
protection filter, hence, without the loss in distal reach such
incorporation produces in most muzzle-heads.
[3056] While ductus requiring treatment over much of their length
will seldom be consistent in lumen diameter, to the extent
possible, the muzzle-head body should match in diameter the most
constricted or stenosed stretch of lumen. In an angioplasty-capable
barrel-assembly, matching these diameters brings the heat-windows
and muzzle-ports to the endothelium so that in a blood vessel, heat
is conducted through the smallest amount of intervening blood, and
the risk of a miniball being deflected prior to penetration is
minimized. Also, side-sweeping radial projection unit brush type
insert tolls then need protrude only slightly beyond the surface of
the muzzle-head body, allowing the wells into which these are
retracted to be shallower.
[3057] The primary limiting factor in reducing the diameter of the
barrel-assembly is the diameter of the motor, which unlike the
distal components of the barrel-assembly cannot be channeled or
blood-grooved to allow at least some blood to flow past it. To
reduce to the extent possible any opportunity for ischemic
complications, the turret-motor is made somewhat smaller in
diameter than the rest of the muzzle-head, and to compensate for
the loss in torque that this reduction in diameter of the stator
and rotor effects, the turret-motor is extended longitudinally
rather than radially. The turret-motor is located at the rear of
the muzzle-head to allow the components that require immediate
access to the lumen to reach as far forward (distally) as possible
and not deduct from the working reach of the muzzle-head down the
vascular tree, especially when the lumen is decreasing in
caliber.
[3058] Placed to the rear of the contacting components, the
proportional increase in motor length essential to preserve torque
does not precede the muzzle-ports to deny depth of access for
implantation, for example. The administration of vasodilating
medication allows some further access down the vascular tree, just
as the administration of bronchodilating medication does so down
the bronchi. When not circulating (systemic), such medication is
injected through a service-channel Whether in center-discharge or
combination-form angioplasty-capable barrel-assemblies, the
incorporation of a radial projection units as discussed below,
necessitates the installation of a distal thromboembolic protective
trap-filter as well.
[3059] Since the release of debris when using radial projection
unit cutting and brushing type tool-inserts is possible at any
time, the trap-filter, as well as deployable simultaneously with
the side-sweeper tool-type inserts, is deployable independently.
Provided no laser or burr is installed, the distal portion of the
central canal in a combination-form (edge-discharge) muzzle-head
with longitudinally arranged recovery electromagnets is available
as a sleeve or silo for storing the trap-filter, the overall length
of the muzzle-head in that case reduced thus increasing the working
reach compared to a muzzle-head with extended nose. However,
installed thus, the central canalmust not admit ductus contents
whether blood into the ejection head even when the trap-filter is
deployed. This kind of muzzle-head configuration can be used with
either an edge- or center-discharge muzzle-head.
[3060] In a combination-form muzzle-head with a rotational
atherectomy burr or laser cable installed, the central axial
position is already occupied, so that a sleeve or silo recess into
which the trap-filter can be retracted while not deployed must be
placed adjacent to the burr or laser, which latter occupies the
central canal, making the recess eccentric (off-center). Whether
installed in the central canal or off-center to accommodate an
excimer laser or atherectomy burr, the silo must have sufficient
capacity to retract several miniballs. As seen in the
cross-sections of FIG. 40 without, and in FIG. 67 with embolic trap
filter, recovery electromagnets 65 are arranged perpendicularly to
the longitudinal axis of the barrel-assembly with antechambers 67
situated in front of the outward directed poles of magnets 65.
[3061] Antechambers 67 are entered through spiral spring 157
spring-loaded trap doors 68, that shown in FIG. 40 double doors to
allow clearance, that are drawn inwards to pass any ferromagnetic
object drawn toward the magnet to either side. In both FIGS. 40 and
67, the arrows indicate the direction of miniball entry into
antechambers 67. As seen in FIG. 67, the magnets are situated to
allow the incorporation of the laser or burr cable in the central
channel 155 while affording sufficient room between them and
adjacent to the cable to place trap-filter silo 156. Accordingly,
neither must one of the recovery electromagnets be reduced in size
nor the nose elongated as would further reduce the working reach in
comparison with the sidewise arranged electromagnets in the
center-discharge muzzle-heads such as those shown in FIGS. 39, 48,
49, and 65.
[3062] VII2d(3)(i). Trap and Extraction Recovery Tractive
Electromagnets in Radial Discharge Barrel-Assemblies for the
Recovery of Loose and Extraction of Mispositioned Miniballs
[3063] Recovery trap electromagnets in barrel-assemblies generally
are addressed above in the section entitled Trap and Extraction
Recovery Tractive Electromagnets for the Recovery of Loose and
Extraction of Mispositioned Miniballs. Those for use in radial
discharge barrel-assemblies are shown in FIGS. 39, 40, 48, 49, 65,
66, and 67. Radial discharge barrel-assemblies are usually small in
gauge, and those for use in the arterial tree must have the
capability to recover miniballs independently of the multiple
backup trapping and recovery means addressed above in section 4g
entitled Emergency Recovery of Miniballs and Stays and in section X
below entitled Steering and Emergency Recovery of Implants with the
Aid of an External (Extracorporeal) Electromagnet and subsections
thereof, among others. Due to the limitations on size imposed by
the gauge of the muzzle-head and the orientation required in
embodiments such as those shown in FIGS. 65 and 66, for example,
the coils or solenoids are usually wound with pure silver wire.
[3064] VII2d(3)(j). Blood-Grooves on Muzzle-Heads for Use in Blood
Vessels
[3065] In a radial discharge monobarrel such as that shown in FIG.
38, the diameter of the barrel-assembly is small, posing less
obstruction to the circulation in a vessel of given caliber than
with multibarrel embodiments. By the same token, multibarrel
embodiments minimize the period that the barrel-assembly must
remain in the lumen, and when the muzzle-ports face in the opposite
direction, cancel out most recoil. When the motor housing is
already as narrow as possible, blood-grooves cannot be routed or
impressed therein. Radial projection catheters need side grooves to
pass blood no less than barrel-assemblies, although
combination-form radial projection catheters need no side grooves
so long as the bore remains empty.
[3066] When, however, muzzle-head 70 is deliberately chosen to fit
flush within the lumen round and about, then as shown in FIGS. 38
and 40, blood-grooves 66, which serve as do side-holes in
conventional catheters, are incorporated to expedite the flow of
blood past the muzzle-head. Blood-grooves 66 are continuous with
the ports and passages cut through the muzzle-head and when
present, the spaces above the shelves represented by the floor of
each enclosed tractive electromagnet chamber seen from the opposite
side.
[3067] The depth of the groove or grooves varies in inverse
proportion to the degree of artery wall radial excursion, which is
dependent upon the elasticity of the wall and the blood pressure
over the segment encircling the muzzle-head, and in direct
proportion to its diameter and length, hence, volume of the
muzzle-head up to the maximum dimensions indicated. Sclerosed
arteries, for example, more constrain the muzzle-head in size and
volume, reducing the number and type of components which might be
included in the muzzle-head, limiting the number of barrel-tubes
and radial projection units, for example.
[3068] One reason that the muzzle-head of a minimally or fully
angioplasty-capable barrel-assembly includes a heat-window at the
nose and usually one about the turret-motor or multiple
heat-windows at the sides is to destroy vulnerable plaque before
the increase in pressure due to intromission of the muzzle-head,
even without coming into contact with the plaque, can cause the
plaque to rupture. The eradication of plaque slightly augments the
clearance surrounding the muzzle-head, reducing the flow-past
resistance. The distinction in pressure before and after plaque
eradication can be locally significant. So long as the bore remains
empty, an angioplasty-capable combination-form barrel-assembly or
radial projection catheter without side-groove or grooves should be
usable off-pump in a sclerosed coronary artery.
[3069] VII2d(4). Forward Drive and Sag Leveling and Stabilizing
Device
[3070] VII2d(4)(a). Use of a Forward Drive Stabilizer
[3071] The barrel-assembly must afford flexibility consistent with
trackability, so that if left unsupported over the length that the
degree of this flexibility determines, it will sag, any deviation
from the longitudinal axis reducing the barrel-tube transit
velocity proportionally until it results in jamming. This situation
is not ameliorated by ensheathing the barrel-assembly within a size
matched radial projection catheter, because these do not overlap in
concentric relation over the extracorporeal segment proximal to the
barrel-assembly power and control housing. During withdrawal,
leveling is not a problem, because the barrel-catheter is pulled
taut.
[3072] When the operator or an assistant advances and withdraws the
barrel-assembly between discharges by moving the airgun, sagging
and buckling of the extracorporeal length of the catheter can be
prevented when the catheter can be supported by a free hand, the
operator adusting the controls. To minimize passive sagging due to
unsupported length in excess of the self-supporting or intrinsic
bridging stiffness of the barrel-catheter, the barrel-assembly
should be chosen for minimal extracorporeal length and the airgun
retracted rather than driven forwarrd manually or with the linear
stage if present if possible to achieve reasonable tautness and
thus minimize this length.
[3073] The interposition of a forward drive and sag leveling and
stabilizing device, or extracorporeal barrel-catheter straightener
and deflection preventing extension linkage, arises when the
transluminal distance to be traversed is large enough to allow the
portion of the barrel-catheter between the airgun muzzle and entry
wound to sag. To minimize nonpassive deviations of the
extracorporeal barrel-catheter from the longitudinal axis, whether
due to bending or buckling should the linear positioning table fail
to achieve penetration in forward drive, transient deflections due
to recoil during discharge, an extensible sleeve is incorporated to
constrain the extracorporeal barrel-catheter to a straight
condition.
[3074] During forward drive, or transluminal advancement, however,
unless means are provided to prevent it, the resistance encountered
will cause the barrel-catheter to suddenly flex or buckle, usually
downward due to gravity. With an ablation or ablation and
angioplasty-capable barrel-assembly, angioplasty, as opposed to
implantation discharge, is usually accomplished manually with the
barrel-assembly removed from an airgun. In use thus, the operator
will grasp the barrel-assembly close enough to the entry wound to
prevent the extracorporeal length of the barrel-catheter from
bending, eliminating the need for a straightening device. A
leveling and stabilizing device prevents passive sagging of the
extracorporeal barrel-catheter while stationary and buckling during
forward drive under the control of the positioning stage.
[3075] If the materials of the barrel-catheter and/or the
barrel-tubes lack the necessary elasticity to continue bending,
either or both can become unusably deformed, or kinked. FIGS. 76
and 77 show two kinds of linkage suitable for a forward drive sag
leveling and stabilizing device. FIGS. 76 thru 78 provide detailed
views of a forward drive sag leveling and stabilizing linkage
device, 77c showing in cross-section the linkage depicted in FIGS.
77a and 77b taken along line K-K' in FIG. 77b. In FIG. 78, a fully
contracted forward drive sag leveling and stabilizing linkage
device incorporating the linkage shown in FIG. 76 is shown as used
with an angioplasty-capable barrel-assembly.
[3076] A forward drive leveling and stabilizing linkage device is
usually included as a part of any radial discharge barrel-assembly
that must be usable with a linear positioning stage whether
ablation or angioplasty-capable, minimally capable, or incapable.
To reach to the depth required with the forward drive leveling and
stabilizing device fully extended, the barrel-catheter must be
correspondingly increased in length. Whereas the need to increase
the discharge exit (`muzzle`) velocity to pass anatomical bends to
which the barrel-catheter must conform is established in advance,
the reduction in exit velocity from incidental sagging or buckling
of the barrel-catheter may occur unpredictably, and detracting from
accuracy, is to be minimized, especially when placement of the
miniballs in a tight formation under positional control must be
precise.
[3077] The exit or barrel-tube muzzle velocity should be constant
for tissue of like pretesting results, this testing addressed below
in the section entitled Testing and Tests. Tissue that differs in
hardness or resistance to penetration by a miniball along an
anatomical bend should be implanted using the barrel-assembly
manually; otherwise, the apparatus must be depended upon to adjust
both the barrel-tube transit velocity and the exit velocity as an
auxiliary function of the positional control system. When imaging
shows the lumen to be free of bends and clearly passable with the
barrel-assembly intended, then modulation of the barrel-tube
transit velocity to compensate for bends and maintain a constant
exit-velocity is unnecessary.
[3078] When moderate bends arouse slight doubt, the modulation of
the barrel-tube transit velocity based upon a pretest recording of
muzzle-head depth versus resistance may be dispensed with, such
modulation then executed in real time. However when the diseased
tissue lining the lumen is continuous and consistent so that the
barrel-tube transit time must be modulated past curves to maintain
a constant exit velocity, but the absolute degree of curvature
arouses doubts about the use of a certain barrel-assembly,
prrecording is used to modulate the barrel-tube transit velocity.
More specifically, the pretest, described in the section below
entitled Testing and Tests, calls for continuously measuring the
resistance force encountered for the instantaneous displacement of
the muzzle-head.
[3079] The test depends upon a proportionality between resistance
to passage of the barrel-assembly and the resistance encountered by
a miniball during discharge. The physics pertaining to these
factors is different and the diameter of the muzzle-head and
barrel-catheter along with several other factors are pertinent;
however, the miniball does retrace the path taken by the
barrel-assembly, and the relation, albeit approximate, is
sufficient for practical use. This is accomplished by recording the
output of a pressure sensor inserted in the stage drive train when
passing the barrel-assembly to be used through the lumen to be
treated under the control of the linear positioning stage to be
used.
[3080] Rotary encoders substantially nullify any advantage in
limiting the linear stage mover to an incremental or stepper motor
merely to simplify translating motor shaft rotation into the
equivalent distance. The test must simulate the actual pass
contemplated, to include the release of a lubricant from the
muzzle-head and use of the turret-motor oscillatory mode to clear a
tighter bend, for eample. Beginning at the same endoluminal
starting position, the recording is then used to adjust, or
modulate, the barrel-tube transit velocity of the airgun during the
discharge pass. Should the maximum allowable resistance reading be
registered, further advancement through the bend is stopped as
having a radius of curvature too sharp to negotiate with the
barrel-assembly of the gauge and flexibility in use.
[3081] For the degree of resistance to correspond to the degree of
bending, the driving force or torque of the stage motor is kept
constant and resistance due to friction kept to a minimum; the
resistance information is not used to modulate the linear stage
motor torque. Except for curves smaller in length than the
muzzle-head, the resistance registered will be slight; however this
will serve as a sufficient indication of the need to adjust the
barrel-tube transit velocity. A continuous recording of the
resistance to a rod passed through a barrel-tube gives a somewhat
closer approximation of the resistance encountered by a miniball as
it transits the barrel-tube during discharge. The test rod is
sufficiently flexible as not to give distorted results by
straightening the barrel-catheter.
[3082] Since either means of testing is used to establish the
miniball transit velocity required on the basis of the
instantaneous resistance encountered, and this resistance
represents the sum of the resistance presented by all of the curves
through which the barrel-assembly has been passed, the
instantaneous reading is usable for the purpose of adjusting the
transit velocity. That is, at any level, the instantaneous
resistance encountered is the sum of resistances passed through
both for the muzzle-head and for the miniball. While the addition
of a combination-form radial projection catheter in ensheathing
relation to the barrel-assembly is disallowed, a more pliant
barrel-assembly such as one with a shorter muzzle-head, and/or
fewer barrel-tubes can be considered, or the decision made to use
stays instead.
[3083] The torpedo-shaped muzzle-head nosing is not a significant
factor in resistance and not advantageously changed. Unless
intermittent ablation, angioplasty, or the use of injection or
other tool-inserts is to remain enabled after discharge has been
initiated, the power and control housing of an ablation or
angioplasty-capable barrel-assembly is slid off. If left on the
barrel-assembly and not kept proximal to the entry wound, its added
weight will increase any tendency to sag. When the control of
insertion and withdrawal are manual, the operator or an assistant
supports the barrel-catheter, the slidable power and control
housing if present kept close to the entry wound for the
convenience of the operator and to minimize bending.
[3084] The power and control housing can be slid along splines
about the outer surface of the barrel-catheter which also prevent
its rotation and allows its use as a torquing (catheter rotation)
device, or torquer during manual use when the barrel-assembly is
disengaged from the airgun, such as to perform an angioplasty.
Provided care is taken to make certain the barrel-catheter is not
sagging behind the operator, that is, between the operator and the
airgun, before each discharge is triggered, a stabilizer is not
needed with a pipe-type barrel-assembly, which is always under
manual control and never driven at a distance from the point of
entry into the body by motorized means needed to achieve a precise
placement over a tiny area.
[3085] When successive discharges are to be placed with a proximity
and accuracy that cannot be accomplished manually, however,
transluminal movement requires the use of a linear positioning
stage. When executed by the linear positioning stage, it is usually
because the intervals separating the discharges are in the
millimetric range, numerous, and to minimize procedural duration,
best delivered at a rate beyond the manual ability of a human
operator. At such times, manual adjustments will usually prove not
sufficiently timed or accurate to maintain the degree of exactitude
necessary and may even contribute to inaccuracy. During manual
control, the forward drive leveler and stabilizer can be separate
from or as shnown in FIG. 78, connected to the twist to lock
connector mounted to the airgun muzzle.
[3086] When not connected at the front of the airgun, the
stabilizer can be placed anywhere along the extracorporeal length
of the barrel-catheter, making it usable whether a power and
control housing is situated distal or proximal thereto when an
ablation or angioplasty-capable barrel-assembly is used for an
ablation or an angioplasty independently of an airgun. Shown fully
contracted with the top and sides jackknife type linkage in FIG.
77b and with the scissors type linkage in FIG. 78, forward drive
stabilizing leveling and extension linkage 159 consists of a
succession of tubular segments for encircling the extracorporeal
barrel-catheter and links to connect and maintain these tubular
segments in longitudinal coaxial alignment as the linkage is pulled
open or extended and pushed closed or contracted over the
extracorporeal portion of the barrel-catheter.
[3087] The portion of the extracorporeal barrel-catheter encircled
by the tubular segments over which the linkage is drawn are
therefore likewise constrained to the longitudinal axis. When the
linkage is used with a linear positioning stage, it is connected at
the airgun muzzle and is usually connected to the rear of the
ablation or angioplasty-capable barrel-assembly power and control
housing. The linkage is therefore extended and contracted to the
same degree and by virtue of the same attachment as the
barrel-catheter to the linear stage-moved airgun. When used
manually, the linkage can but need not be connected at either
end.
[3088] Turning now to FIGS. 78 and 83, when under the control of a
linear positioning stage or table, stationary base 150 of linear
positioning stage 160 is connected to the distal end of forward
drive stabilizing and leveling extension linkage 159 by bilateral
(paired on the far side not shown) linking arms 161 so that the
distal end of the linkage with connecting flange 162 is held
stationary while proximal end connecting female component 103 and
male component 75 as detailed in FIG. 73 of push and twist to lock
constituting the flange connector and barrel-catheter 44 are pulled
proximally, the barrel-assembly then withdrawn through through the
entry wound.
[3089] When positioning stage 160 drives barrel-catheter 44
forward, its slidable power and control housing 163 is held by arms
161, so that barrel-catheter-ensheating radial projection catheter
power and control housing 164, which is unitized with its more
forward radial projection unit-containing barrel portion, moves
forward and away from its initially juxtaposed position in contact
with barrel-assembly power and control housing 164. Alternatively,
flange 162 used to attach slidable barrel-assembly power and contol
housing 163 to holding arms 161 is made detachable so that the
flange and not housing 163 itself is held by bilateral restraining
arms 161, housing 163 then moving with housing 164 but freely
slidable by hand.
[3090] That is, when linear stage 160 withdraws the barrel-assembly
from the body, the receding stage simultaneously pulls linkage 159
open over the added length of barrel-catheter 44. In a duplex
barrel-assembly, radial projection catheter power and control
housing 164 is generally that housing the fluid pump if fluid
controlled radial projection units are included. In so doing, the
distance from the base of the stage to the distal end of forward
drive stabilizing and leveling extension linkage 159 is held
constant and sufficiently distad to prevent sagging or buckling. To
allow the power and control housing to be slid along the
barrel-catheter so that it can be kept close to the entry incision,
it is not connected to the front or distal end of the linkage.
[3091] When ablation, angioplasty, or the use of radial projection
assembly tool-insert injectors, for example, is to be alternated
with implant discharge, the power and control housing is connected
directly to the airgun muzzle with the leveling device distal to
it. To allow either connection of the housing to keep it close to
the entry wound or to the airgun, all of the interchangeable
connectors are of the twist to lock connecting flange type, the
housing having such a connecting flange fastened to its proximal or
back side. While usually unnecessary, especially with an assistant,
a leveling and stabilizing linkage can be used during manual
control to steady the barrel-catheter, but it is then adjusted in
extension and slid along by hand rather than connected at either
end as when used as shown in FIGS. 78 and 83 with a positioning
stage.
[3092] If the barrel-assembly is of the ablation or
angioplasty-capable type with a power and control housing 163,
distal end of forward drive stabilizing and leveling extension
linkage 159 is fastened to proximal or rear face of housing 163,
held close to the entry wound. Fastening of forward drive
stabilizing and leveling extension linkage 159 at its proximal end
to the distal (front) face of the twist-to-lock connection flange
comprising female component 103 and male component 75 on the
barrel-catheter 44 and at its distal end to flange 162 at the
proximal face of barrel-assembly power and control housing 163
depends upon whether it is a permanent part of the barrel-assembly
or an attachment.
[3093] As a permanent part of the barrel-assembly linkage 159 is
resistance or spot welded if metal or glued if plastic at the stage
base end but left temporarily fastenable at the housing flange to
allow barrel-assembly power and control housing 163 to be slid off
so that a combination-form radial projection catheter can be
slipped over the barrel-assembly to constitute a duplex (composite,
bipartite) barrel-assembly. Depending upon the application, the
leveling device can be attached at either, neither, or both ends,
neither when manually adjusted, and both under automatic positional
control, for example, or can be situated in front of instead of
behind the power and control housing.
[3094] Using a duplex barrel-assembly to place a tight formation of
miniballs, the unsheathed barrel-assembly is passed, usually to the
most distal site for treatment at the start of the procedure.
Whether the leveling device is needed is decided based upon the
likelihood that the extracorporeal unsheathed length of the
barrel-catheter will bend. For any barrel-assembly, since a need to
reverse direction can always arise, a barrel-assembly should always
incorporate or allow the addition of a leveling and stabilizing
linkage for its length plus the increase in length to accommodate
the device. Barrel-assemblies intended for attachment as desired of
an extension linkage should afford this extra length as well and
allow removal of the barrel-catheter connecting flange to allow
such a linkage to be slid over the proximal end.
[3095] Whether a permanent component or an attachment, the length
of the linkage when extended should accommodate leveling for a
barrel-assembly of given length without the need to add or remove
links. Each consecutively delivered miniball discharge is then
positioned by the control system in withdrawal. If the
barrel-assembly is to be ensheathed within a radial projection
catheter to use more tool-inserts than the number of radial
projection units in the muzzle-head can accommodate, then only the
unsheathed portion of the barrel-catheter need be supported by an
expansion linkage.
[3096] Since the added sheath increases the diameter and stiffness
and therefore reduces the trackability of the barrel-assembly over
the length that the two overlap, support by the extension linkage
is required during insertion of the unsheathed barrel-assembly,
addition of the projection catheter usually eliminating the need
for support or reinforcement and therewith, a supporting linkage.
As an attachment, the linkage is added to the barrel-assembly by
forcibly sliding off the friction fit connecting flange from the
barrel-catheter and slipping the linkage over the barrel-catheter
whether a power and control housing is distal thereto. If present,
the housing is attached to the front (distal face) of the
connecting flange at the distal end of the linkage.
[3097] Attachment of the linkage at its proximal end to the
connecting flange at the airgun muzzle and at its distal end and to
the connecting flange resistance or spot welded if metal or glued
if plastic to the rear (proximal side) of the housing is by means
of twist-to-lock connection flanges of the same kind as are used to
fasten the barrel-assembly to the airgun muzzle. The paired flanges
are likewise twisted to lock into ganged, or back to back,
relation. To allow bilateral restraining arms 161 to be adjusted in
length, these are made in two overlapping parts, one containing a
central lengthwise slot to allow a threaded stud fastened to the
other part to project through the slot so that it can be slid along
the slot for tightening at the length to which the distal end of
forward drive stabilizing and leveling extension linkage 159, and
if present, power and control housing 163 is to be fixed in
distance from positional stage base 150.
[3098] Wing nut 165 allows the parts of restraining arms 161 to be
tightened at any point along the slot thus making the overall
length of bilateral link arms 161 adjustable for leveling and
stabilizing devices of different length on different
barrel-assemblies. Bilateral restraining arms 161 allow housing 163
to be adjusted in position along barrel-catheter 44 regardless of
whether forward drive stabilizing and leveling extension linkage
159 is fully contracted. The two parts of bilateral restraining
arms 161 include on their facing side complementary detents in the
form of a small elevation on one arm and complementary depression
in the other that lock the two in linear relation when wing nut 165
is tightened. Distal leveling device connecting flange 162 has to
either side small retractable spring-loaded studs that enter a hole
toward the distal end of each restraining arm 161 when slid over it
locking arms 161 in place against its sides.
[3099] The distal end is removed by depressing the studs with the
end of a sharp object or gently separating the arms to either side.
Ordinarily, bilateral arms 161 are permanently fastened to the base
150 of linear stage 160 by means of snugly fastened rivets that
allow arms 161 to be rotated into position when needed. Since an
emergency condition related or unrelated to the procedure might
intervene to necessitate that the procedure be stopped at any
moment, duplicate cancel (stop, abend) keys are provided on the
barrel-assembly and airgun control panels. Either stops the linear
positioning stage and discharge as tied thereto at the same
instant. With discharge accomplished as an auxiliary function of
the positional control system, should the barrel-assembly stop
moving, discharge is abended, precluding perforation of the treated
ductus as the result of multiple discharges at the point of the
stoppage.
[3100] A forward drive stabilizer can be incorporated into any
barrel-catheter, to include combination-forms that incorporate a
rotational atherectomy burr or laser. These must, however, be
confirmed as sufficiently flexible to avoid perforating the ductus
during insertion or forward drive. Since no such atherectomizer is
needed once the angioplasty portion of an operation has been
completed, the free or proximal end of the barrel-assembly can be
disconnected from the console cable for connection to the airgun.
Removal of the side-socket connected cable assists in constraining
the barrel-catheter to the longitudinal axis when connected to the
airgun.
[3101] VII2d(4)(b). Structure of Forward Drive Stabilizing and
Leveling Extension Linkage
[3102] As shown in FIGS. 76 thru 78, leveling and stabilizing
extension linkages constitute mixed kinematic chains, which overall
open-ended, comprise series of closed kinematic chain segments in
parallelogram loops, that of FIG. 76 connected at the sides of each
tube segment 166, and that of FIG. 77 at the top, bottom and sides
of each successive pair of tube segments 166. Since vertical links
167 attach to the top and bottom, and horizontal links 168 attach
to the sides of each tube segment, the horizontal and vertical
linkages do not obstruct with one another as would be the case were
the top link of one tube segment and the bottom link of that
adjacent unified and joined to each tube segment at the sides.
[3103] Alternative linking schemes, such as alternatively side then
top and bottom linking successive tube segments is not preferred as
yielding a structure with less longitudinal rigidity. The stiffness
needed must not detract from the ease and smoothness of expansion
and contraction. Tube segments 166 are cut from nonferromagnetic
sheet stainless steel or a nonferrous metal such as copper or
aluminum. To avoid seizing (catching, sticking) along the
barrel-catheter, the internal surface of the tube segments 166 must
be smooth and provide sufficient clearance from the outer surface
of the barrel-catheter.
[3104] This clearance is too small to allow the use of a linkage
with tube segments of given internal diameter to support
barrel-catheters of different gauge. The linkage must be tight,
that is, have little play, but be fully extendable and remain
straight when fully extended when held at one end with no
barrel-catheter passing through it. Links 167 in FIG. 76 and 167
and 168 in FIG. 77 of linkage 159 are die cut from sheet metal of
the same material and joined by solid or clevis pin type round head
rivets with spring washers, preferably of the Belleville disc ring
type, interposed between the heads of the rivets and the arms of
the linkage, or nylon bearings with compression fit heads, for
example.
[3105] VII2d(5). Direction of Radial Discharge Barrel-Assembly
Muzzle-Head on Discharge as Antegrade (Advancing, Forward, Distad,
Prograde) or Retrograde (Withdrawing, Backward, Proximad)
[3106] The trap-extractor magnet assembly in a radial discharge
barrel-assembly necessarily positioned distal to the muzzle-ports,
prior to the first discharge when placement of the stent-jacket is
to follow, the magnetic field generated by the trap-extractor
magnet assembly intercepts the passage of any loose miniball down
the lumen. To avoid the risk of disrupting any miniballs that have
already been implanted, the barrel-assembly is advanced forward
from discharge to discharge thus causing the magnetic field to move
away from rather than to pass these. A parachute or trawler type
fishing net configured filter (trap-filter, filter-trap) deployed
ahead of (distal to) the leading end (nose) of the muzzle-head is
also available to trap loose miniballs. When the procedure has been
completed and the barrel-assembly is to be withdrawn, the amperage
through the electromagnets is reduced to zero and the
barrel-assembly withdrawn.
[3107] If any miniballs failed to implant, then the rotary magazine
clip hole for the number a position or barrel-tube to implant the
missed positions is used to place those missed when withdrawing. If
a miniball or miniballs had been retrieved, then the amperage is
reduced to the lowest value that will allow the trapped miniballs
to be held through any radial accelerations or recoils of the
muzzle-head to follow and the barrel-assembly to be withdrawn
without disrupting the miniballs that have been implanted, and once
these are past, the amperage may be returned to a higher value. If
not matching the lumen in diameter, the barrel-assembly can be
nudged into contract with the lumen wall with the aid of an
external hand-held electromagnet as described below and blanked out
rotary magazine clips used to implant only the side in contact.
[3108] VII2e. Simple Pipe and Radial Discharge Barrel-Assembly
Common Elements
[3109] VII2e(1). Barrel-Catheters, Barrel-Tubes, and
Barrel-Assemblies
[3110] The barrel-catheters of simple pipes, comprising a single
barrel intended for use primarily in the airway are one and the
same tube. Single (monobarrel) and multiple barrel (multibarrel)
radial discharge barrel-assemblies are designed to be usable in the
bloodstream where air embolism and fouling of the mechanism by the
inflow of blood must be averted even were discharge inadvertent
with no miniball ahead of the expulsive gas. The barrel-tubes in
radial discharge barrel-assemblies must therefore be enclosed
within a jacket, or barrel-catheter, that allows the internal
equalization of differences in pressure. Whereas simple pipes are
intended for use in vasa other than blood vessels so that the
presentation of a thromogenic metal (stainless steel) surface is
not an issue, radial discharge barrel-assemblies may be used in any
type vas.
[3111] Those for use in the vascular tree must be coated with low
friction fluoropolymer such as polytetrafluoroethylene.
Flexibility, hence trackability, and see-through clarity are
improved when the barrel-catheter consists of undyed
tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride
terpolymer (THV resin), and pliancy increased when combined or
coextruded with another fluoropolymer. Except at the muzzle-hole, a
radial discharge barrel-catheter is otherwise substantially
airtight. The introduction of gas into the bloodstream is averted
by providing a return path of less resistance than is posed by the
blood even in antegrade (downstream) flow.
[3112] This is achieved by perforating the barrel-tube or tubes so
that gas may circulate within the enclosed barrel-assembly. The use
of various tubing materials to include coextruded or compound
tubing makes possible a wide range of pliancy and diameter in the
unitary catheter, and this is significantly augmented in multiple
barrel barrel-assemblies where the barrel-tubes may be made of
different materials and adjusted in distance from the central axis.
barrel-catheter of an ablation or angioplasty-capable
barrel-assembly is splined with sliding contacts in the valleys so
that a power and control housing can be slid along it.
[3113] The flexibility of multiple barrel-tube barrel-assemblies,
such as those shown in FIGS. 39 and 41 thru 45 described below, is
also affected by the distance from the longitudinal axis of the
barrel-catheter of (noncoextruded) barrel-tubes 74 through the
holes 91 in and intervals along the barrel-catheter separating the
centering devices 95 used to position the barrel-tubes 74, as
addressed below in the section entitled Centering Devices
(Centering Disks); and the presence, materials, and angles of
blood-tunnels 96 seen in FIGS. 39, 41, and 42, addressed below in
the section entitled Hypoxia and Ischemia-averting Elements, 2.
Blood-tunnels.
[3114] When the diameter is too small to incorporate tunnels as
buttresses, these are made solid or omitted. For increased
flexibility or trackability and/or to absorb the shock of recoil,
the barrel-catheter can include convoluted segments at intervals
variable in length, interval, and number. By discontinuously
applying the convolution impressing mold to the straight-walled
tubing as originally extruded, the tube manufacturer can make
tubing with any pattern of alternately convoluted and
straight-walled segments. The barrel-catheter also includes a
convoluted segment for flexion and recoil absorption.
[3115] The torque ratio or resistance to twisting and bending
deformation of the barrel-catheter depends upon several variables,
to include:
[3116] 1. The intrinsic pliancy of the material or if coextruded
materials.
[3117] 2. The wall thickness.
[3118] 3. Diameter of the barrel-catheter.
[3119] 4. The intrinsic pliancy of the material of which each
barrel-tube is made.
[3120] 5. The radial distance set by the centering devices of the
barrel-tubes from the longitudinal axis.
[3121] 6. The longitudinal interval separating adjacent centering
devices.
[3122] 7. Whether the barrel-catheter incorporates
blood-tunnels.
[3123] 8. Whether the operator chooses to preinsert a catheter or
rod of widely variable pliancy down an available barrel-tube.
[3124] 9. The incorporation into the barrel-catheter of convoluted
segments, the lengths of and intervals separating any convoluted
segments.
[3125] 10. Whether the centering devices are left free to rotate at
the edges or have been bonded to the barrel-tubes and the internal
surface of the barrel-catheter, and
[3126] 11. The resistance to twisting of any other lines running
through the barrel-catheter, such as the wires to the turret-motor
and the electromagnets and the optical fibers when a laser, for
example, has been incorporated, and so on.
[3127] Bonding together the parts of barrel-assemblies and special
radial projection unit catheters is preferably accomplished by
means of ultrasonic welding. Alternatively, in addition to
one-component tissue compatible cyanoacrylate cements,suitable
adhesives for bonding together the component parts of
barrel-assemblies include those cured with ultraviolet light, such
as DYMAX Corporation, Torrington, Conn. 200-series catheter
adhesives, more specifically, DYMAX 208 CTH-F. This single
component adhesive cures in seconds with ultraviolet light curing
systems that are also available from DYMAX Corporation, Torrington,
Conn. Numerous other adhesivesthat might be used include Master
Bond Polymer System EP3HTMED.
[3128] The use of materials and incorporation of internal
structural features to be described and the selection of
barrel-assemblies to avoid nonessential length allow approximating
a 1:1 torque ratio. The muzzle-head is provided with tantalum
markings for high radiopacity. Anatomy permitting, this allows even
an exceptional muzzle-head that lacks a turret-motor to be
accurately rotated to the desired position manually. The resistance
to bending of the extracorporeal portion of the barrel-assembly is
more significant in ablation and ablation and angioplasty-capable
barrel-assemblies, which are removed from the airgun and forward
drive and sag leveling and stabilizing device for independent use.
Numerous means for reducing the flexibility of the barrel-assembly
are provided herein.
[3129] These include the material or compound material such as
coextruded tubing, thickness of the barrel-catheter and
barrel-tubes, number of blood-tunnels if any, interval separating
barrel-tube centering devices and whether these are peripherally
bonded to the internal surface of the barrel-catheter. Since even
with centering devices and blood-tunnels and without the weight of
a power and control housing, excessive length causes sagging
(drooping) if not kinking, overall barrel-assembly catheter length
should be kept to a minimum. Sagging is further reduced through
shifting the weight of a slidable power and control housing, as
addressed below in the section entitled Slidable Ablation or
Ablation and Angioplasty-capable Barrel-assembly Power and Control
Housing.
[3130] Stiffening elements are more dense in the extracorporeal
barrel-catheter. The intracorporeal barrel-catheter with
blood-tunnels that prove excessively stiffening can be made more
flexibile or trackable by including convolutions or convoluted
segments. The use of a cooling catheter to return the termperature
of the turret-motor and/or recovery tractive electromagnets when
sent heating current for thermal angioplasty, as will be described
below, is more effective when the diameter or gauge of the cooling
catheter can be larger as passable down the central canal of a
center-discharge barrel-assembly rather than down a barrel-tube as
is necessary when using a combination-form barrel-assembly that
incorporates an atherectomy burr or laser cable at the center. The
general concept of a cooling catheter is not new.
[3131] Considered in cross-section, the heat conduction path from
within the otherwise insulative barrel-tube to the turret-motor and
electromagnets is asymmetrical (off-center, eccentric); however,
for equalizing the pressure of discharge to avoid arterial or
venous gas embolism (air embolism) (see, for example, Mendenhall,
M. L and Spain, D. A. 2007. "Venous Air Embolism and Pressure
Infusion Devices," Journal of Trauma 63(1):246; Wittenberg, H. G.
and Allison, J. R. 2006. "Venous Air Embolism," eMedicine,
available at http://www.emedicine.com/emerg/topic787.htm) the
barrel-tube has been perforated over the distal segment aligned to
these heated elements, which perforations pass the heat. The exit
velocity of the barrel-tubes within a barrel-assembly are not
equalized as necessitates that all be perforated exactly alike.
[3132] VII2e(2). Connectors (Couplings) for Quick Release and
Reconnection of the Barrel-Assembly to the Airgun with Proper
Alignment
[3133] An interventional airgun must accept any barrel-assembly of
like gauge or caliber, whether a simple pipe or an ablation or
ablation and angioplasty-capble barrel-assembly. Except for size,
the mechanical connection of the barrel-assembly to the airgun is
substantially the same in embodiments that otherwise differ. This
connection must allow the operator to immediately disengage the
barrel-assembly for manual transluminal advancement, withdrawal, or
rotation and just as quickly reinsert it into the airgun barrel to
resume discharge with the assurance that the security of connection
and alignment of the barrel-tubes to the holes respective of each
in the rotary magazine clip will be exact.
[3134] VII2e(3). Twist-to-Stop and Lock Connector (Twist Lock
Connector, Keyed Spring Lock Connector)
[3135] In use, the barrel-assembly is selected and manually
introduced into the lumen through a conventional incision and
introducer sheath. There is no guidewire. Once the position along
the lumen is reached, the proximal end of the barrel-assembly is
engaged within the airgun barrel with the extracorporeal segment
straight. If, depending upon the pliancy of the specific
barrel-assembly, the extracorporeal length results in some downward
bowing at the center, then the slack is taken up by backing up the
muzzle-assembly with the linear stage as described below until the
muzzle-head can just be seen to move. If the muzzle-head must be
advanced or withdrawn midprocedure, the linear stage is used or the
barrel-assembly can be disengaged from the airgun and manually
repositioned.
[3136] When manually repositioned, upon reconnecting the
barrel-assembly, the linear stage is used to `trim off` or take up
any slack and thus straighten the barrel-assembly. Unless
deliberately activated, discharge remains disabled, eliminating the
possibility that a bend might affect discharge. Use of the
apparatus is described in greater detail following the section on
the linear stage and in conjunction with a description of the
control panel. This is accomplished through the use of a
twist-to-lock joint or coupling that incorporates short spring
steel tabs with central depressions to receive protrusions on the
complementary tabs that are mounted about the barrel-assembly.
[3137] While a joint of the kind described requires a slight twist
to connect or to disconnect, this is preferable to the relative
lack of tight connection provided by more costly and complex joints
that require no twisting motion, such as the quick disconnect hose
couplings used in vacuum cleaners. In the simple pipe and air
pistol, only one barrel-tube need be aligned. However, in a
multiple barrel radial discharge barrel-assembly, an end-plate at
the proximal end of the barrel-assembly is essential to stabilize
the position of the proximal ends of the barrel-tubes, and the
rotary distance or throw of the complementary tabs must be such
that the stops situate the barrel-assembly in the airgun barrel
with the barrel-tubes aligned to their respective holes in the
rotary magazine clip.
[3138] To allow the precise fit (without play) of the
barrel-assembly in the airgun barrel without sticking or seizing
midprocedure, both the external surface of the portion of the
barrel-assembly to be inserted into the airgun barrel and the
internal surface of the airgun barrel, which must exactly match in
diameter are made of low friction, generally fluoropolymer
materials, such as polytetrafluoroethylene. Mechanical connection
of the barrel-assembly within the barrel of the airgun by friction
fitting is avoided as risking resistance to removal if unavoidable
midprocedurally.
[3139] Regardless of caliber, type, or number of barrels,
mechanical connection of the barrel-assembly to the airgun is by
means of a push-and-rotate-to-engage keyed flange type connector or
coupling, as shown in FIG. 73. Receiving or female component 103 of
the flange connector is mounted to the front of airgun muzzle 105
(use of the term `muzzle` should not lead to confusion with the
muzzle-head or muzzle-probe at the distal end of the
barrel-assembly seen as 70 in the radial monobarrel shown in FIG.
38 and as 73 in the radial multibarrel shown in FIG. 39). In FIG.
73, male component of twist to lock flange connector 75 is mounted
around barrel-catheter 72 at the distance from end-plate 99 that
barrel-assembly 72 is to enter airgun barrel 107.
[3140] In a barrel-assembly not for use independently of the airgun
that draws power not from an inmate power and control housing but
rather by connection to the airgun power supply, or in an
independently usable ablation or ablation and angioplasty-capable
barrel-assembly also controllable from the airgun control panel,
multiple electrical contact connector terminal set 101 seen in FIG.
72 is brought into contact with the counterpart electrical contacts
within the airgun chamber, end-plate 99 then flush fit within the
airgun chamber as seen in FIG. 74 just short of as not to impede
the movement of the rotary magazine clip 15 in FIGS. 31, 32, and
74. To engage the barrel-assembly in the airgun barrel, tabs 102
are inserted into slots 104.
[3141] Rotating the end of the barrel-assembly clockwise causes the
tabs to slide beneath the compressive ceiling overlying rotary
slideway 108, which closed off at the extremity of rotation stops
the tabs at the exact rotational angle at which the barrel-tubes in
barrel-catheter 72 are aligned to their respective barrel holes in
the rotary magazine clips shown as 15 in FIGS. 31, 32, and 74.
Simple pipe and radial discharge monobarrels are most often used
with the muzzle-port directed downwards. Monobarrels require no
barrel-tube alignment.
[3142] The component of the stop and lock ring component of the
twist-to-lock connector fitting mounted about the barrel-catheter
seen as 47 in the monobarrels of FIGS. 31, 32, and 38 and 75 of the
multibarrel seen in FIGS. 39, 74, and 75 and the
mono-multibarrel-neutral view of FIG. 73, has tabs 102 shown in
FIG. 73 which fit into slots 103 in the complementary receiving or
female component fitted about the front of the airgun muzzle, as
shown in FIGS. 73 and 74. Twist-to-lock fitting 47 both establishes
the limit of intromission of the barrel-assembly into the barrel of
the airgun and locks the barrel-assembly in position with its
distal end just short of as not to impede the movement of the
rotary magazine clip 15 in FIGS. 31, 32, and 74.
[3143] In accordance with the industry convention for indexing or
incrementally rotating clip 15 when the trigger is pulled, notches
48 about the outer edge of rotary magazine clip 15 in FIGS. 31, 32,
and 74 are successively engaged by pawl 49. The rotary magazine
clips are inserted by placing the center hole 43 over axle 50
mounted to supporting post 51. To remove one rotary clip and
replace it with another whether to replenish a certain type
miniball or change the type used is accomplished midoperatively in
four seconds or less. These notches are on the reverse face of the
rotary magazine clips and thus unseen in FIGS. 29 and 30.
[3144] Shown in FIGS. 31, 32, and 38 as part 47 and in FIGS. 39,
73, and 74 as 75, the male portion of stop and twist-to-lock
connector, has at least two tabs that fit into the slots in a
circular archway, or if the archway is divided for each, into the
end-openings of the divided circular archway, that is mounted to
the front of the airgun muzzle, so that once entered into the
slots, twist-to-lock fitting 47 can be slid around through the
circular slideway or slideways beneath the ceiling over the archway
of the slideway to the slideway ends and so locked in position both
angularly and longitudinally.
[3145] In all barrel-catheters, the proximal portion for entry into
the airgun barrel has an outer diameter that precisely fills the
airgun bore or inner diameter of the airgun barrel, whether the
airgun barrel has been modified with, for example, a
polytetrafluoroethylene lining added to cover (blanket over) the
rifling as well as to reduce the caliber, or the barrel is original
in a dedicated interventional airgun, as later described.
Accordingly, engaged thus, the outer surface of simple pipe
monobarrel barrel-catheter 44 in FIGS. 31 and 32 is flush
throughout its airgun-intromitted length against the bore of airgun
barrel 57 with the proximal end of the barrel-catheter 44
positioned immediately before the miniball hole or holes 42 in the
rotary magazine clips shown in FIGS. 31, 32, and 74.
[3146] This means for engaging the proximal end of a
barrel-assembly in an airgun is common to all barrel-assemblies and
thus addressed in a separate section below. Barrel-catheter 44 is
made of a single length of tubing with the curve toward the tip 45
maintained by the bond that unites the upper surface of the
tractive electromagnet 46 housing 56 to the underside of the
barrel-catheter 44. To minimize the risk of injury to the lumen
wall or larynx by gouging, the pointed end of the simple pipe
barrel-assembly is girdled about with a soft guard (bumper, shield)
52, similar to a dam used in dentistry. The guard is made of
expanded polytetrafluoroethylene (ePTFE) or a pharmacologically
active leachant and plasticizer-free engineered nylon polyether
block amide resin such as Pebax.RTM. 3533 tubing.
[3147] It is stretched over and fixed in position about the
barrel-catheter by its own restorative force. Guard 52 overextends
the distal end of the barrel-catheter slightly, typically by 1
millimeter. To accurately rotate the muzzle-head requires that the
barrel-assembly resist twisting, or have a torque ratio approaching
1:1. Since radial discharge barrel-assemblies present an outer
contour that is rounded and smooth, are provided with a remotely
controllable motorized muzzle-head turret, and the muzzle-head is
routinely wetted with a lubricant such as those specified above in
the section entitled Stent-jacket Insertion Tools, before entry,
the risk of gouging, twisting, and stretching injury is
avoided.
[3148] When a single barrel radial discharge barrel-assembly is
used in the airway, mucus serves as a lubricant. When a
combination-form muzzle-head includes an excimer laser (addressed
below), the ends of the optical fibers can be wetted with lubricant
as well, the laser quickly vaporizing this upon activation. The
degradation products liberated by such vaporization must, of
course, be innocuous in the bloodstream. Lubricant can interfere
with the cutting action of a rotational atherectomy burr so that
lubricant should be used sparingly to avoid the muzzle-head or
probe nose.
[3149] The means of testing for endothelial adhesion and delivery
of lubricant to the muzzle-head midprocedurally are described below
under the section on testing. Broadly, whenever the risk of injury
due to transluminal, manual, or motor torqueing (rotatory) movement
of the barrel-assembly is present, a lubricant is used. Whenever
the barrel-catheter of a barrel-assembly used in the vascular tree
approaches the diameter of the muzzle-head, the entire
barrel-assembly is wetted with a lubricant. Depending upon the
materials used to make the barrel-catheter and muzzle-head, the
outer surface of both components can be coated with one of the
lubricious materials specified below.
[3150] An outer coating of polytetrafluoroethylene will generally
obviate the need for lubrication. Alternatively, silver-based
coatings such as is available from Spire Corporation, Bedford,
Mass. do not materially detract from lubricity but do appear to
reduce the risks of Infection, thrombosis, and stenosis (see
Bambauer, R., Mestres, P., Schiel, R., Schneidewind-Muller, J. M.,
Bambauer, S., and Sioshansi, P. 2001. "Large Bore Catheters with
Surface Treatments Versus Untreated Catheters for Blood Access,"
Journal of Vascular Access 2(3):97-105).
[3151] VII2e(4). Engagement of the Barrel-Assembly in the
Airgun
[3152] The barrel-assembly, such as a two or four-way
barrel-assembly as depicted in FIG. 39, is capped off at its
proximal end with an end-plate 99 that receives and holds the
proximal ends of the barrel-tubes, which open through the
end-plate, and must be positioned in precise alignment with their
respective holes in the rotary magazine clip or in a monobarrel
barrel-assembly, to the fore the miniball to be discharged. In
order to maintain this precise alignment, the end of the
barrel-catheter must fit flush within the chamber of the airgun. In
a noncombination-form barrel-assembly with center discharge
muzzle-head, a slit valve in end-plate 99 is used for insertion of
a cooling catheter or other external cable or line as described
above in the section entitled Cooling Catheters
(Temperature-changing Catheters).
[3153] However, because entry into the barrel-assembly at the rear
rather than through the side by means of a side-socket obstructs
the barrel-assembly from insertion into the airgun, such use of the
end-plate as an end-socket does not allow, for example, chilled gas
to be delivered to the treatment site to chemically and thus
physiologically retard or stabilize the inner layers of the ductus
during discharge. The incorporation of a side-socket into the
battery pack allows the ablative and angioplasty capabilities of
the barrel-assembly, such as a supplementary or `touch up` ablation
or angioplasty, to be applied during discharge without the need to
disengage the barrel-assembly from the airgun, thus interrupting
the procedure, possibly degrading precision when discharge is
machine-controlled.
[3154] The barrel-catheter is inserted into the airgun barrel to a
distance just short of, as not to come into contact with, the
rotary magazine clip as it advances by indexed rotation from one
discharge load to the next. Referring now to FIG. 74,
barrel-catheter 72 is inserted into the barrel of the airgun 107 up
to the limit allowed by stop-and-lock ring 75, which engaged within
the female component of the twist-and-lock connector that is
mounted to the muzzle of the airgun places the end-plate just short
of contact with the rotary magazine clip 15 with barrel-tubes 74
perfectly aligned to the hole in the rotary magazine clip
respective of each barrel-tube.
[3155] Increased interchangeability of barrel-assemblies and
airguns raises the risk for a barrel-assembly not designed for use
with a given airgun or an airgun that has been configured for
different operation, such as the use of a different rotary magazine
clip or different bore insert. Barrel-assemblies must therefore
bear clear compatibility indicia. Since a tag will be removed, this
is best accomplished by molding specification on every
barrel-assembly and color coding adaptors for insertion in the
airgun. Making the chamber of transparent plastic allows the color
of the rotary magazine clip to be seen from the outside.
[3156] VII2e(5). Barrel-Assembly End-Plate
[3157] The centering device at the proximal end of the
barrel-assembly is the end-plate (terminal plate), 99 shown in
FIGS. 38, 39, 73, 74, with a detailed view provided in FIG. 72.
Unlike the proximal ends of the gas return pressure relief
channels, to maximize the propulsive force and minimize any
opposing inflow of blood when the muzzle-ports at the sides of the
muzzle-head are introduced into an arterial lumen, joint between
the nozzle and rotary magazine clip should be tight and flush. That
is, only the proximal end of the miniball propulsion joints need be
airtight in the distal direction. By contrast, the proximal ends of
the relief channels when proximally continuous all the way back to
the end-plate must vent pressure not dissipated within the
barrel-catheter.
[3158] Venting is usually by dissipation within the
barrel-assembly, but can be at the terminal plate through or
without a slit membrane or through holes or one-way valves in the
extracorporeal segment of the barrel-catheter. When dissipated
internally, the centering devices have holes to allow the back
pressure gas to pass through proximad. In such a barrel-assembly,
end-plate 99 in FIGS. 38, 39, 73, 74, with a detailed view provided
in FIG. 72, usually incorporates a membrane slit valve, but not the
gas pressure equalization vent or outlet holes 92 such as shown in
FIGS. 41 thru 45. Since the airgun chamber must be airtight to
prevent the loss of propulsive gas pressure, the proximal end
(end-plate) of the barrel-assembly may be seen as redundant in this
airtightness, which is precautionary.
[3159] More specifically, as clarified in the section above
entitled Airgun and Electrical Connections and Controls of
Barrel-assemblies by Functional Type, an ablation or
angioplasty-incapable barrel-assembly is never used without its
proximal end engaged in the airgun chamber. Reciprocally, so long
as it remains in separate use during an angioplasty, an
angioplasty-capable barrel-assembly never performs a discharge
function as to generate internal pressures that must be dissipated
within it to conserve propulsive gas pressure and to avoid gas
embolism if discharged in the vascular tree. A barrel-assembly of
latter type is provided with a slit-valve of a stiffer elastomeric
sheeting material at its end-plate to allow entry into the central
canal for use as a service-channel and affords an opening for a
cooling catheter.
[3160] When engaged in the airgun chamber, the latter makes the
proximal end of the barrel-assembly airtight. The end-plate fixes
the barrel-tubes in position for exact alignment with their
respective holes in the rotary magazine clip. Electrical conductors
97 that course through the longitudinal axis of the barrel-catheter
exit proximally through central aperture 100, with the conductors
passing radially in bonded relation to the face of end-plate 99 to
end on terminal 101. End-plate 99, molded in any suitable plastic,
such as polyethylene, polyethylene terephthalate, or polystyrene,
contains a simple slit valve made of elastomeric sheet material,
such as polyurethane, chlorosulfonated polyethylene, silicone, or
fluorosilicone.
[3161] The slit valve serves both to relieve excess pressure in the
peribarrel space and as an entryway through which to admit a test
rod, lubrication injection catheter, or turret-motor and/or
electromagnet assembly rapid cooling catheter (cooling capillary
catheter) when necessary, as addressed above in the section
entitled Cooling Catheters (Temperature-changing Catheters). For
nonthermal angioplasty using side-brushes (above and below), the
turret-motor is connected to the drive control electronics to
rotate the muzzle-head only when the anatomy makes manual rotation
difficult or risky.
[3162] Except that when the turret-motor stator has just been used
as a heating element for thermal angioplasty, a brief interval must
be allowed for cooling, end-plate connection of the turret-motor
positional drive control electronics has the advantage of allowing
a barrel-assembly that battery powered is nontethered and otherwise
independent of the airgun to be immediately and intermittently
connected to the drive controls only when the turret-motor is
needed for rotation. During discharge, the turret-motor must be
connected to the drive control electronics. Alternatively, the
electrical connection of the barrel-assembly can be by means of
terminals on the side of the barrel-assembly just distal to the
proximal length of it inserted into the airgun barrel.
[3163] VII2e(6). Electrical Connection of the Barrel-Assembly to
the Airgun
[3164] Turning now to FIGS. 74 and 75, barrel-tubes 74 must be
positioned in proper alignment with their respective miniball
loading holes in rotary clip 15. Clip 15 forcibly rotated by pawl
49 in FIGS. 31 and 32, making end-plate 99 or facing (veneering) it
with polytetrafluoroethylene--except inside the miniball loading
holes as would militate against miniball retention--allows flush
abutment of end-plate 99 against the front of rotary clip 15
without impeding its rotation. To allow an ablation and
angioplasty-incapable radial discharge barrel-assembly without an
inmate power source to be removed and reinserted from the airgun
for occasional manual use independently of the airgun without
concurrent disconnection from the airgun power supply and a loss of
power, electrical connection of the barrel-assembly within the
airgun chamber is made to the electrical contacts within the airgun
chamber by placement of connecting cable 109 in FIG. 75 on the
outside of the barrel-assembly distal to or in front of its
junction with the barrel of the airgun.
[3165] Mounting a rechargeable battery pack local to the electrical
terminals at the outside of the barrel-assembly allows both the
removal and reinsertion of the barrel-assembly as needed without
the need for an external cable that dangles at the side if only
when the barrel-assembly is inserted in the airgun when this is of
little if any consequence. Whether the result is equivalent to an
ablation and/or angioplasty-capable barrel-assembly depends upon
the type and number of radial projection units built into the
barrel-assembly or added by ensheathment within a combination-form
radial projection catheter as constitutes a bipartite or duplex
barrel-assembly.
[3166] Eliminating the need to remove the barrel-assembly from the
airgun and connect it to a separate power supply or battery pack,
then disconnect the power source and reinsert the barrel-assembly
into the airgun, an external cable of adequate lengh that maintains
connection to the airgun power supply throughout allows quicker
alternation between use of the barrel-assembly for discharge and
independent use than does either a power supply or battery.
Intermittent `touch-up` ablation, angioplasty, or drug delivery as
necessary is thus quickly interjected during discharge
implantation. Since free removal from and reinsertion into the
airgun of the barrel-assembly without a loss of power requires that
end-plate 99 remain clear, electrical connection of the external
cable is through a set of electrical terminals mounted to the side
of the barrel-assembly.
[3167] For visual clarity, FIG. 72 shows electrical terminal 101,
which is brought into contact when the barrel-catheter is fully
flush within the airgun chamber as shown in FIG. 74 and rotated at
the twist to lock connector at the airgun muzzle, as thicker than
actual; in order not to protrude as would require splining the
airgun barrel, terminal 101 is actually countersunk into the wall
of barrel-catheter 72. With such an electrical connection, the
twist to lock connector shown in FIG. 73 consisting of stop and
twist to lock lock ring 75 and muzzle fitting 103 establishes the
correct rotational angle not only for aligning the barrels but also
brings the electrical terminal shown or a multiplicity thereof into
contact.
[3168] Simple pipe barrel-catheters such as those shown in FIGS. 31
thru 33 require no turret-motor, but are equipped with a tractive
recovery electromagnet with antechamber trap assembly that requires
connection to the airgun power supply by means of a two-conductor
cable. Any of the exemplary connector types specified below for six
conductor connectors, to include former military specification
C-5015 subminiature D type connectors containing two conductors for
each trap-extraction electromagnet, can be used. Power can also be
drawn from a separate power supply or battery attached proximally
to the barrel-catheter. This is usual with a simple air pistol that
has been modified for interventional use as addressed above in the
section entitled Simple Airgun Modified to Allow Limited
Application, for example, but not in special-purpose interventional
airguns.
[3169] In a modified air pistol, the electrical cable is continued
down the front of the pistol grip to a separate power supply. In an
interventional airgun built for that purpose, the power supply is
contained within the same cabinet as the other components, with
thermal insulation, heat sinks, and physical separation used to
isolate sources that generate conflicting temperatures. The two
wire conductor plugs into a socket toward the proximal end of the
barrel-assembly where the latter exits past the outside of the
airgun barrel. The wire is fixed to the underside of the
barrel-catheter with cyanoacrylate cement, or a DYMAX Corporation
200-CTH-series cement. As with the electrical connection to a
radial discharge or multiple barrel barrel-assembly, rather than
allowed to drop from the side of the barrel-catheter, the wire or
cable is held by clamps to the actuation handpiece or pistol
grip.
[3170] The multiple barrel barrel-assembly has a turret-motor and
trap-extraction electromagnet assembly, each of which must be
independently controllable. The conventional six-conductor with
circular connectors or discrete wire ribbon cable connected to the
remote power supply contains two wires each for the turret-motor
and each of the tractive electromagnets and terminates in a plug,
which can be of the strip header or long latch and eject header
kind. In a multibarrel radial discharge barrel-assembly such as
those shown in FIGS. 39, 48, 49, 65, and 66, cable 97 shown in FIG.
75 includes eight-conductors and passes down through central
channel 155, shown occupied by a laser 169 in FIG. 66, of the
barrel-assembly to electrical terminal board 106.
[3171] Terminal board 106 mounted to the outside of the
barrel-assembly at a small distance from the airgun muzzle includes
eight points of connection or contact posts, preferably of the
phono pin plug and jack type for quick changes midprocedurally as
necessary, of which two each are for the turret-motor, two each for
either separately adjustable electromagnet, and two are to actuate
the radial projection unit. Once fully inserted into the airgn
barrel, the entire slack of cable 109, centered on twist-to-lock
connector consisting of 103 and 75 above, hangs down at the side of
the airgun barrel. The slack is usually disregarded. If preferred,
the slack is taken up by a small wire take-up spring reel that to
avoid impeding the operator applies no greater retractive force
than necessary.
[3172] The spring reel (not shown) is mounted to the airgun chamber
close to a connection board and connectors similar to that on the
barrel-assembly 106 thus connecting to the airgun power supply.
Clip hangers 110 permanently affixed to the underside of the airgun
barrel support the slack as it is taken up by the spring reel. This
representation must be exemplary, the number of conductors actually
required depending upon the number of components, the operative
modes of each, and controls necessary to adjust these. When the
type airgun is always paired with ablation and ablation or
angioplasty-capable barrel-assemblies requiring the same number of
connections, the separate plugs and jacks are replaced with a
single multi pin plug and socket that makes and breaks the
different connections at once and thus quickly.
[3173] For a barrel-assembly requiring 8 connections, an 8-pin DIN
connector is used. A turret-motor, for example, can be used only as
a mover or also as a heating element. Distad, the wires for the
electromagnets continue past the port portion of the muzzle-head
through the nose or anterport projection. These barrel and
electrical connections end on the proximal outer surface of the
barrel-assembly with a six-contact terminal which receives these
lines from the remote power supply. While the trap-extraction
electromagnets use ceramic woven insulated silver wire to generate
magnetic field intensities sufficient to extract mispositioned
miniballs despite their small size, the conductors connected to
these are of greater gauge and not susceptible to melting by heat
conduction.
[3174] The 6 conductor-3 pair plug and socket may be any of many
kinds, to include those stated above for ribbon cable;
minirectangular; modular; or registered RJ12 or RJ25. These
electrical lines connect on the outside of the
receiver-barrel-assembly junction by means of connectors. The power
supply of a modified airgun is remote, whereas that in a dedicated
airgun is an integral component. Inside the barrel-assembly, the
cable is not ribbon but round and courses distad through the
central canal defined by the barrel-tubes, the four conductors for
the trap-extraction electromagnets continuing through the center of
the muzzle-head splay chamber.
[3175] VII2f. Radial Discharge Barrel-Assembly Elements
[3176] VII2f(1). Tube Polymer Nonintrinsic Barrel-Catheter
Flexibility (Bendability, Trackability) Setting and Altering
Elements
[3177] VII2f(1)(a). Tubing Materials for Barrel-Catheters and
Radial Discharge Barrel-Tubes
[3178] Suitable tubing for the barrel-catheter and the barrel-tubes
that it conducts pose numerous possibilities. Depending upon the
diameter of the ductus, hence, barrel-assembly, the number of
barrel-tubes can be from one to four or more, and can be separate
as to pass at variable radiii from the center, or coextruded as a
multiple-lumen tube of which the luminal tubes are separable for
outward flaring toward the distal end. The incorporation of a.
Blood-tunnels, as described below in the section entitled Hypoxia
and Ischemia-averting Elements, 2. Blood-tunnels, and b. The
spacing apart of noncoextruded barrel-tubes by means of centering
devices, as described below in the section entitled Centering
Devices (Centering Disks), introduces stiffness that must take the
corresponding detraction in barrel-assembly intraoperative
bendability (trackability) into account.
[3179] The number and type of these elements must therefore be
coordinated with the other factors that affect trackability, such
as the tube polymers, their wall thicknesses, diameters, and the
distances from the longitudinal central axis of the barrel-catheter
of the barrel-tubes. Depending upon the dimensions, rigidity,
frictional character, and so on, sought in a given type of
barrel-assembly, the material, or if coextruded or coated, the
materials of the tubes in that type of barrel-assembly, are chosen
on the basis of empirical testing. The central canal in a
center-discharge barrel-assembly or any available barrel-tube in
either a center or edge discharge barrel-assembly can be used to
insert a hollow tube or solid rod of a diameter less than that of
the path taken made of any polymer free of polymerization residue
to alter the flexibility of the barrel-assembly at any time whether
before or after entry into the body or before or after reaching the
site for treatment, to include a cooling catheter or cooling
capillary catheter as described below.
[3180] The torque ratio or twisting characteristic of the
barrel-catheter can be increased with relatively little effect on
flexibility by bonding the centering devices to the inner surface
of the barrel-catheter. The tubing in any barrel-assembly should be
neither so pliant as to bend with little lateral force and thus
change the rolling resistance as to necessitate constant adjustment
of the airgun, which invites human error, nor so stiff that the
bends encountered with either brachial or femoral entry cause it to
kink or injure the lumen wall. For transluminal advancement by the
linear positioning table, bending is prevented by a sheathing about
the extracorporeal length.
[3181] The tubing of the barrel-catheter 44 can be made of any of a
number of materials, to include compound (coextruded) tubing to
provide, for example, polytetrafluoroethylene within nylon,
polytetrafluoroethylene within vinyl, polytetrafluoroethylene or
nylon inside with polytetrafluoroethylene or medical grade vinyl
outside, or an internal thin coating or thicker layer of
polytetrafluoroethylene for `bore` slipperiness and overall
stiffness, coextruded with an outer layer of any of numerous
materials, such as expanded polytetrafluoroethylene, Pebax.RTM., or
Tygon.RTM. S-50-HL for pliancy and soft contact with the larynx and
tracheal lumen. Varying the relative thickness of each of these
layers allows a continuous wide range of complementary pliancies
and torqueabilities in the simple pipe barrel-catheter. Barrel
tubing materials having a higher coefficient of friction recommend
an inside barrel lining coat of polytetrafluoroethylene.
[3182] Polytetrafluoroethylene within vinyl, for example, affords
relatively greater pliancy, but at the expense of stiff
torqueability and greater friction. Nonessential bends in the
barrel-catheter proximal to the patient will increase the rolling
resistance for and reduce the exit velocity of the miniballs. To
minimize nonaxial discharge, the least sufficient length of
barrel-catheter between patient and airgun that allowsthe free
manipulation of the barrel-assembly should be used. That is, the
barrel-assembly should be as short as practicable. The
incorporation into the muzzle-head of a `chronometer` to actuate an
alarm when as the result of rolling resistance, miniball velocity
drops below a certain value, is discounted due to the lack of space
available distal to the front of the electromagnet.
[3183] Whereas a radial discharge barrel-assembly will generally be
used for high density implantation necessitating leveling of the
extracorporeal length for use of the automatic interval increment
table, with a simple pipe barrel-assembly, monitoring for bends in
the barrel-catheter to prevent reductions in exit velocity can be
directly and practicably accomplished by incorporating
piezoresistive or optical fiber strain gauges along the
barrel-assembly at intervals over the proximal length that remains
outside the patient. A threshold excessive output voltage generated
within these can be made to actuate an audible alarm.
[3184] However, vigilance by members of the operating team to any
more than slight changes in the conformation of the barrel-assembly
obviates the additional cost for a hyperflexed condition detection
and alarm system. The `bore` of the barrel-catheter varies with
that of the miniballs to be discharged, generally ranging between
1.0 and 2.1 millimeters. Regardless of the procedure or type
barrel-assembly in use, once the apparatus has been positioned and
is in use, further movement, much as with a dental hand-piece, is
slight and substantially limited to the working end or muzzle-head.
The airgun is adjusted for the conformation of the barrel-catheter,
and significant deviations from this conformation must be noted and
the procedure interrupted to change the adjustment.
[3185] That once in use movement is limited to a short length of
the barrel-assembly toward the distal end does not justify the
interposition of a section of tubing that differs in pliancy from
the rest. To assist in orientation and the gauging of distances,
radiopaque calibrative markings are applied along the outside of
the pipe by etching and applying tantalum. If the outside of the
barrel-catheter is made of polytetrafluoroethylene, Acton
Technologies, Inc. FluoroEtch.RTM. or W.L. Gore.RTM. and
Associates, Inc. Tetra-Etch.RTM. or blown-ion air plasma type
corona, or flame surface treated, for example, is used to prepare
by scarifying the surface for improved adhesion of the tantalum
coating. Further details regarding the mechanical connection, and
the electrical connection, of the barrel-assembly to the airgun are
described below.
[3186] VII2f(1)(b). Centering Devices (Centering Disks)
[3187] For fixing barrel-tubes in radial distance from the central
axis of the barrel-catheter, a centering (or `centring`) device, as
shown for use in a four-way radial discharge barrel-assembly in
FIGS. 43 thru 45, is used. FIG. 42 shows a partially cross-section
of a four-barrel radial-discharge barrel-assembly through a
centering device taken along line G-G' in FIG. 41 where bilateral
blood-tunnels 96 are shown in FIG. 42 as off-section and receding
into the distance and peribarrel space 98 omitted as displaced by
the blood-tunnels at the level depicted.
[3188] In FIGS. 43 thru 45, centering devices have a central hole
90 to pass the electrical conductor for supplying electrical or
fluid power to the turret-motor and tractive electromagnets,
barrel-tube holes 91 to pass the barrel-tubes, and gas pressure
equalizing perforations 92, which allow the discharge pressure that
escapes through the perforations in the length of the barrel-tubes
within the body to access the entire peribarrel space 98 in FIGS.
48 and 49 as but overlain in the view of FIG. 42 and so become
equalized within the barrel-catheter.
[3189] In a barrel-assembly with either a center- or edge-discharge
muzzle-head that allows a cabled device such as a fiberoptic
endoscope or laser to be passed down through the central channel to
the nose, such as shown in FIG. 66, the centering devices include a
center hole 90 of the larger diameter required, with side-holes
then used for electrical or fluid conductors. Incorporation into
the barrel-assembly of a central cabled device such as a fiberoptic
endoscope or laser necessitates a larger center hole in the
centering devices shown in FIGS. 43 thru 45 and a center hole in
the nose as shown in FIG. 67 for a combination-form barrel-assembly
that allows the exchanging of cabled devices during use.
[3190] FIG. 39 provides a side view of centering devices 95 along
line G-G-- as well as a blood-tunnel 96 along line F-F' in a two-
or four-barrel radial discharge barrel-assembly where these have
been longitudinally separated as not to superimpose. FIG. 41 then
brings these together where the views along lines F-F' and G-G' in
FIG. 39 could be longitudinally condensed and allow detail. At
intervals along the barrel-assembly sufficient to prevent sagging
of the barrel-tubes, the outer edges of the centering devices are
bonded to the inside of the barrel-catheter, and the edges of the
holes for the barrel-tubes 91 are bonded to the barrel-tubes by
means of an adhesive. The center hole 90 when used to pass through
wire insulation is not bonded.
[3191] Depending upon the materials of which the centering device,
barrel-tubes, and barrel-catheter are made, the adhesive used is,
for example, NuSil Technologies MED-1037 or MED3-4013, DYMAX
Corporation 200-CTH-series cement, cyanoacrylate cement, Master
Bond.RTM. EP42LV, or Loctite Hysol Cool Melt.RTM.. By allowing the
radial spacing among the barrel-tubes to be increased as in FIG.
44, the centering devices not only keep the lines passing through
at a constant distance from one another and the barrel-catheter but
allow the flexibility as well as the torque ratio of the
barrel-assembly to be reduced.
[3192] Along with the materials, which can be coextruded, and
thickness of the barrel-catheter and barrel-tubes, this factor is
used to reduce the tendency of portions of the barrel-assembly
outside the body to flex and thus increase the rolling resistance
to discharge of the miniballs. Trackability and the tendency to sag
both due to flexibility, the number of centering devices used,
whether these are made of less elastic material and glued to all
tubes in contact can be used to adjust the flexibility if the
barrel-assembly. A sufficient number where all are glued allows the
barrel-assembly to support itself without sagging over shorter
distances but reduces trackability but may not be adequate to
negate the need for the antisag linkage device shown in FIG. 78
during automatically positioned discharge.
[3193] For barrel-tubes of given hardness, gradually reducing their
radial distances as the leading or distal end of the
barrel-assembly is approached enhances trackability around
anatomical bends. If extended proximad past elastomeric joint 111
in FIGS. 48, 49, 65, and depending upon the flexibility of the
cabled device, FIG. 66, the pressure equalization perforations in
and toward the distal ends of the barrel-tubes contributes to
flexibility as well. Flexibility and torque ratio can be adjusted
over a wide range not just over the entire length but over
different segments of the barrel-assembly according to the
longitudinal interval separating the centering devices and whether
these are bonded to the internal surface of the barrel-catheter and
other lines that pass through.
[3194] Usually this is used to reduce the tendency for the
extracorporeal length of the barrel-catheter to fold at the entry
portal when the operator lets go, especially when the slidable
power and control housing of an ablation or ablation and
angioplasty-capable barrel-assembly is not advanced to the body so
that the barrel-catheter folds under its weight. long with the
materials and dimensions of the parts of the barrel-assembly and
whether these are bonded, the flexibility and torqueability, or
resistance to longitudinal twisting, of the barrel-assembly can be
adjusted over the entire length of the barrel-assembly or different
segments by gradually changing the radial spacing of the
barrel-tubes.
[3195] This is done by using centering devices that incrementally
separate (diverge, radially spread apart) or more centrally gather
(converge) the barrel-tubes, as shown most convergent in FIG. 43
and least convergent in FIG. 44. To create paths for blood to pass,
metal in the spindle distal to the spindle neck journaled in the
through-bore rotor of the turret-motor is removed. The periperhal
openings to these passages or blood-ports are machined for
continuity with the blood-grooves described below that course
longitudinally along the outside of the muzzle-head. Yet another
method for obtaining greater flexibility with a given combination
of barrel-tubes over the entire lengh or segments of the
barrel-assembly is to reduce the diameter of the
barrel-catheter.
[3196] When the barrel-catheter is not made thus, larger and
smaller diameter barrel-catheters are joined by telescoping the end
of the narrower into the wider, the joint bonded with an adhesive
or by welding and externally bevelled and rounded to prevent
abrasion of the lumen wall. Joining segments that differ in
diameter such that these are not directly interdigitable or
telescopable but sufficiently different as to necessitate the
insertion of tubing of intervening diameter or pressure-sensitive
tape is discouraged as likely to result in seizing or rubbing of
the joint against the lumen wall regardless how ledgeless or
nonabrupt the outer surface. If necessary, an external hand-held
electromagnet is used to assist in steering the muzzle-head through
sharper turns by attracting the turret-motor and magnet cores in
the otherwise nonmagnetic muzzle-head.
[3197] The barrel-assembly is made stiffer by 1. Using a
barrel-catheter of larger diameter, 2. Making the barrel-tubes and
barrel-catheter of stiffer materials, 3. Distancing the
barrel-tubes farther radially from the longitudinal axis, and 4.
Incorporating blood-tunnels, as described below. Incorporation into
the barrel-assembly of a photo-ablation laser also adds stiffness.
The caliber of the implants is decided purely on the basis of the
medical requirement and never manipulated merely to change the
stiffness of the barrel-assembly. Change in these factors also
changes the torque ratio of the barrel-assembly, which is further
variable by leaving the outer edges of the centering devices
unbonded or bonded to the internal surface of the
barrel-catheter.
[3198] VII2f(2). Embolic Trap Filter in Radial Discharge
Muzzle-Heads for Use in the Vascular Tree
[3199] Preemptive angioplasty with the heat-windows and/or laser
built into the muzzle-head should completely disintegrate any
debris released from the fracture of vulnerable plaque by contact
with the muzzle-head. Furthermore, since the muzzle-head discharges
to the side and extends forward of the miniball exit-holes, a
miniball cannot be discharged in the forward direction. However, in
any off-pump procedure, should the recovery electromagnets remain
unenergized through human error, a miniball that becomes loose
between the side of the muzzle-head and the intima will be carried
forward by the bloodstream. Since forward movement by this mean
retains none of the momentum of discharge as would perforate it, a
run-ahead or distal embolic filter can remain deployed throughout
discharge to provide additional protection not only against
thromboembolism but embolization by a miniball.
[3200] By intercepting and holding any miniball that would
otherwise pass downstream, the filter supports the recovery
electromagnets and any prepositioned external electromagnet
midprocedurally. An impasse-jacket adds yet another means for
trapping a miniball that enters the circulation midprocedurally,
but is one that remains effective over any interval following the
procedure. Most studies indicate that despite increased procedural
time, the risk of special complications, and additional expense,
distal embolic protective filters are withal beneficial (see
section 4d(2) entitled Ductus Wall Tumefacients and Sprouse, L. R.,
Peeters, P., Bosiers, M. 2005. "The Capture of Visible Debris by
Distal Cerebral Protection Filters During Carotid Artery Stenting:
Is It Predictable?," Journal of Vascular Surgery 41(6):950-955;
Wholey, M. H., Jarmolowski, C. R., Wholey, M. and Eles, G. R 2003.
"Carotid Artery Stent Placement--Ready for Prime Time?," Journal of
Vascular and Interventional Radiology 14(1): 1-10).
[3201] At the same time, others have shown that by causing intimal
abrasion and denudation, distal filters actually generate much
thromboembolic debris (see, for example, section 4d(2) entitled
Ductus Wall Tumefacients and Muller-Hulsbeck, S., Stolzmann, P.,
Liess, C, Hedderich, J., Paulsen, F., Jahnke, T., and Heller M.
2005. "Vessel Wall Damage Caused by Cerebral Protection Devices: Ex
Vivo Evaluation in Porcine Carotid Arteries," Radiology
235(2):454-460; Maleux, G., Demaerel, P., Verbeken, E., Daenens,
K., Heye, S., Van Sonhoven, F., Nevelsteen, A., and Wilms, G. 2006.
"Cerebral Ischemia After Filter-protected Carotid Artery Stenting
is Common and Cannot be Predicted by the Presence of Substantial
Amount of Debris Captured by the Filter Device," American Journal
of Neuroradiology 27(9):1830-1833). Vasospasm, dissection, and
guidewire entrapment have been reported (Vijayvergiya, R., Otaal,
P. S., Bagga, S., and Modi, M. 2010. "Symptomatic Carotid Vasospasm
Caused by a Distal-protection Device during Stent Angioplasty of
the Right Internal Carotid Artery," Texas Heart Institute Journal
37(2):226-229).
[3202] The current concensus favors the use of a distal embolic
protective filter when preliminary intraductal ultrasonography,
computer-assisted pixel distribution analysis of duplex ultrasound
scan images, palpography, thermography, catheter-based
thermography, near-infrared spectroscopy, angioscopy indicates the
presence if not the fine structure of vulnerable plaque (but see
Wolff, M. R., Resar, J. R., Stuart, R. S., and Brinker, J. A. 1993.
"Coronary Artery Rupture and Pseudoaneurysm Formation Resulting
from Percutaneous Coronary Angioscopy," Catheterization and
Cardiovascular Diagnosis 28(1):47-50), digital subtraction
angiography, magnetic resonance imaging, computed tomography,
multislice spiral computed tomography, nuclear methods, endoluminal
means of imaging, or optical coherence tomography (see, for
example, Lee, J. M., Bang, J. I., Koo, B. K., Hwang, D., Park, J.,
and 7 others 2017. "Clinical Relevance of 18F-Sodium Fluoride
Positron-emission Tomography in Noninvasive Identification of
High-risk Plaque in Patients with Coronary Artery Disease,"
Circulation. Cardiovascular Imaging 10(11). pii: e006704; Bec, J.,
Phipps, J. E., Gorpas, D., Ma, D., Fatakdawala, H., and 3 others
2017. "In Vivo Label-free Structural and Biochemical Imaging of
Coronary Arteries Using an Integrated Ultrasound and Multispectral
Fluorescence Lifetime Catheter System," Scientific Reports
7(1):8960; Wieringa WG1, Lexis CP1, Lipsic E1, van der Werf HW1,
Burgerhof JG2, and 9 others 2017. "In Vivo Coronary Lesion
Differentiation with Computed Tomography Angiography and
Intravascular Ultrasound as Compared to Optical Coherence
Tomography," Journal of Cardiovascular Computed Tomography
11(2):111-118; Lee, J. H., Hwang, Y. N., Kim, G. Y., Shin, E. S.,
and Kim, S. M. 2017. "Analysis of Cardiovascular Tissue Components
for the Diagnosis of Coronary Vulnerable Plaque from Intravascular
Ultrasound Images," Journal of Healthcare Engineering 2017:9837280;
Costopoulos, C., Brown, A. J., Teng, Z., Hoole, S. P., West, N. E.,
Samady, H., and Bennett, M. R. 2016. "Intravascular Ultrasound and
Optical Coherence Tomography Imaging of Ccoronary Atherosclerosis,"
International Journal of Cardiovascular Imaging 2016 32(1):189-200;
Ma, T., Zhou, B., Hsiai, T. K., and Shung, K. K. 2016. "A Review of
Intravascular Ultrasound-based Multimodal Intravascular Imaging:
The Synergistic Approach to Characterizing Vulnerable Plaques,"
Ultrasonic Imaging 38(5):314-331; Celeng, C., Takx, R. A.,
Ferencik, M., and Maurovich-Horvat, P. 2016. "Non-invasive and
Invasive Imaging of Vulnerable Coronary Plaque," Trends in
Cardiovascular Medicine 26(6):538-547; Ma, D., Bec, J.,
Yankelevich, D. R., Gorpas, D., Fatakdawala, H., and Marcu, L.
2014. "Rotational Multispectral Fluorescence Lifetime Imaging and
Intravascular Ultrasound: Bimodal System for Intravascular
Applications," Journal of Biomedical Optics 19(6):066004; Bec, J.,
Ma, D. M., Yankelevich, D. R., Liu, J., Ferrier, W. T., Southard,
J., and Marcu, L. 2014. "Multispectral Fluorescence Lifetime
Imaging System for Intravascular Diagnostics with Ultrasound
Guidance: In Vivo Validation in Swine Arteries," Journal of
Biophotonics 7(5):281-285; Ren, J., Zhang, J., Xu, N., Han, G.,
Geng, Q., and 4 others 2013. "Signature of Circulating MicroRNAs as
Potential Biomarkers in Vulnerable Coronary Artery Disease," Public
Library of Science One 8(12):e80738; Garcia-Garcia, H. M., Gonzalo,
N., Granada, J. F., Regar, E., and Serruys, P. W. 2008. "Diagnosis
and Treatment of Coronary Vulnerable Plaques," Expert Review of
Cardiovascular Therapy 6(2):209-222; Schaar, J. A., Mastik, F.,
Regar, E., den Uil, C. A., Gijsen, F. J., and and 3 others 2007.
"Current Diagnostic Modalities for Vulnerable Plaque Detection,"
Current Pharmaceutical Design 13(10):995-1001; Hamdan, A., Assali,
A., Fuchs, S., Battler, A., and Kornowski, R. 2007. "Imaging of
Vulnerable Coronary Artery Plaques," Catheterization and
Cardiovascular Interventions 70(1):65-74; Saia, F., Schaar, J.,
Regar, E., Rodriguez, G., De Feyter, P. J., and 8 others 2006.
"Clinical Imaging of the Vulnerable Plaque in the Coronary
Arteries: New Intracoronary Diagnostic Methods," Journal of
Cardiovascular Medicine (Hagerstown, Md.) 7(1):21-28; Schaar, J.
A., Mastik, F., Regar, E., den Uil, C. A., Gijsen, F. J., Wentzel,
J. J., Serruys, P. W., and van der Stehen, A. F. 2007 "Current
Diagnostic Modalities for Vulnerable Plaque Detection," Current
Pharmaceutical Design 13(10):995-1001; Hamdan, A., Assali, A.,
Fuchs, S., Battler, A., and Kornowski, R. 2007 "Imaging of
Vulnerable Coronary Artery Plaques," Catheterization and
Cardiovascular Interventions 70(1):65-74).
[3203] In light of these findings and the fact that the
incorporation of a trap-filter, even without the additional
incorporation of radial projection units, reduces working depth
down the vascular tree, the selection of a barrel-assembly that
incorporates a trap-filter must rest upon clinical judgment made on
a case by case basis through preliminary imaging of the specific
condition to be treated. Since the apparatus described herein are
not limited to use in the vascular tree, distal protection is not
appropriate in every application or embodiment. However, the use of
radial projection unit side-sweeping tool-insert brushes in the
vascular tree would generate debris that an improved filter should
eliminate without generating debris of its own. The release of
debris by contact of the arterial wall with the muzzle-head is
discussed below in the section entitled Thermal ablation or
angioplasty- (Lumen Wall Priming Searing- or Cautery-) capable
Barrel-assemblies.
[3204] Thus, at least the location and method for incorporating a
filter into different embodiments to be described should be shown,
regardless of whether a filter is actually incorporated in any one.
Accordingly, this unresolved controversy is resolved by providing
for the incorporation of a trap-filter in each of the various
embodiments to be described. When not used following an angioplasty
and on the first entry pass with an angioplasty-capable
barrel-assembly, a muzzle-head with heat-window nose-cap can be
used to release heat to the surrounding lumen wall preempting the
release of potentially embolizing debris. When concern for the
presence of vulnerable plaque distad to its reach is not an issue,
the trap-filter can also be deployed to protect against the release
of embolizing debris. Filter deployment is also independently
controllable and the filter membrane selected for resistance to
modification in material properties by exposure to the release of
heat from the nose.
[3205] A number of recent advancements have been made toward the
noninvasive detection of vulnerable plaque, to include
multidetector row or multislice computed tomography scanning with
iodinated nanoparticles dispersed with surfactant in a product
called N1177 produced by Nanoscan Imaging of Lansdale, Pa. as
contrast agent (see Hyafil, F., Cornily, J. C., Feig, J. E.,
Gordon, R., Vucic, E., Amirbekian, V., Fisher, E. A., Fuster, V.,
Feldman, L. J., and Fayad, Z. A. 2007. "Noninvasive Detection of
Macrophages Using a Nanoparticulate Contrast Agent for Computed
Tomography," Nature Medicine 13(5):636-641). Vulnerable plaque
contains more macrophages and is higher in temperature and acidity
than healthy arterial wall tissue. Means had already existed to
detect plaque as reasonably prognostic for an acute event (see, for
example, Gronholdt, M-L. M., Nordestgaard, B. G., Schroeder, T. V.,
Vorstrup, S., and Sillesen, H. 2001. "Ultrasonic Echolucent Carotid
Plaques Predict Future Strokes," Circulation 104(1):68-73).
[3206] Newer noninvasive imaging methods can make arterial
inflammation, neovascularization of the vasa vasorum, and/or the
extent of stenosis clear enough to signal the need for deploying a
distal embolic protective filter. These include:
[3207] a. The use of gas filled microbubbles as ultrasonic contrast
agents (see, for example, Feinstein, S. B. 2006. "Contrast
Ultrasound Imaging of the Carotid Artery Vasa Vasorum and
Atherosclerotic Plaque Neovascularization," Journal of the American
College of Cardiology 48(2):236-243; Feinstein, S. B. 2004. "The
Powerful Microbubble: From Bench to Bedside, from Intraductal
Indicator to Therapeutic Delivery System, and Beyond," American
Journal of Physiology. Heart and Circulatory Physiology
287(2):H450-H457; Dayton, P. A and Rychak, J. J. 2007. Molecular
Ultrasound Imaging Using Microbubble Contrast Agents," Frontiers in
Bioscience 12:5124-142; Kaufmann, B. A. and Lindner, J. R. 2007.
"Molecular Imaging with Targeted Contrast Ultrasound," Current
Opinion in Biotechnology 18(1):11-16).
[3208] b. Magnetic molecular resonance imaging with gadopentetic
acid (gadopentetate dimeglumine, Gd-DTPA) contrast agent
(Briley-Saebo, K. C., Mulder, W. J., Mani, V., Hyafil, F.,
Amirbekian, V., Aguinaldo, J. G., Fisher, E. A., and Fayad, Z. A.
2007. "Magnetic Resonance Imaging of Vulnerable Atherosclerotic
Plaques: Current Imaging Strategies and Molecular Imaging Probes,"
Journal of Magnetic Resonance Imaging 26(3):460-479; Amirbekian,
V., Lipinski, M. J., Briley-Saebo, K. C., Amirbekian, S.,
Aguinaldo, J. G., Weinreb, D. B., Vucic, E., Frias, J. C., Hyafil,
F., Mani, V., Fisher, E. A., Fayad, Z. A. 2007. "Detecting and
Assessing Macrophages in Vivo to Evaluate Atherosclerosis
Noninvasively Using Molecular MRI," Proceedings of the National
Academy of Sciences of the United States of America 104(3):
961-966). c. Multichannel, high-resolution laser scanning
fluorescence microscopy (see Pande, A. N., Kohler, R. H., Aikawa,
E., Weissleder, R., and Jaffer, F. A. 2006. "Detection of
Macrophage Activity in Atherosclerosis in Vivo Using Multichannel,
High-Resolution Laser Scanning Fluorescence Microscopy," Journal of
Biomedical Optics 11(2):021009),
[3209] d. Intraductal fluorescence spectroscopy (see Tawakol, A.,
Castano, A. P., Anatelli, F., Bashian, G., Stern, J., Zahra, T.,
Gad, F., Chirico, S., Ahmadi, A., Fischman, A. J., Muller, J. E.,
and Hamblin, M. R. 2006. "Photosensitizer Delivery to Vulnerable
Atherosclerotic Plaque: Comparison of Macrophage-targeted Conjugate
Versus Free Chlorin(e6)," Journal of Biomedical Optics
11(2):021008.).
[3210] e. Positron emission tomography (Tawakol, A., Migrino, R.
Q., Bashian, G. G., Bedri, S., Vermylen, D., Cury, R. C., Yates,
D., LaMuraglia, G. M., Furie, K., Houser, S., Gewirtz, H., Muller,
J. E., Brady, T. J., and Fischman, A. J. 2006. "In Vivo
18F-fluorodeoxyglucose Positron Emission Tomography Imaging
Provides a Noninvasive Measure of Carotid Plaque Inflammation in
Patients," Journal of the American College of Cardiology
48(9):1818-1824; Elmaleh, D. R., Fischman, A. J., Tawakol, A., Zhu,
A., Shoup, T. M., Hoffmann, U., Brownel,1 A. L., and Zamecnik, P.
C. 2006. "Detection of Inflamed Atherosclerotic Lesions with
Diadenosine-5',5'''-P1,P4-tetraphosphate (Ap4A) and
Positron-emission Tomography," Proceedings of the National Academy
of Sciences of the United States of America 103(43):
15992-15996).
[3211] f. Multidetector-row computed tomography (Alasnag, M.,
Umakanthan, B., and Foster, G. P. 2008. "Accurate Determination of
High-risk Coronary Lesion Type by Multidetector Cardiac Computed
Tomography," Journal of Invasive Cardiology 20(7):361-363; Mowatt,
G., Cummins, E., Waugh, N., Walker, S., Cook, J., Jia, X., Hillis,
G. S., and Fraser, C. 2008. "Systematic Review of the Clinical
Effectiveness and Cost-effectiveness of 64-slice or Higher Computed
Tomography Angiography as an Alternative to Invasive Coronary
Angiography in the Investigation of Coronary Artery Disease,"
Health Technology Assessment 12(17):iii-iv, ix-143).
[3212] To prevent the passage downstream of dislodged
atherothrombogenic debris as would result in distal embolization,
deployment of shaving or brush-type tool-inserts is accompanied by
the automatic deployment of a distal embolic protective
trap-filter. The filter deployment mechanism is part of the
barrel-assembly, no portion thereof discarded. Replacement filters
are meant to be discarded after one-time that precedes the
expiration date stamped on the package. Replacement filters are
packaged after sterilization with ethylene oxide gas and attach
toward the distal end of the vanadium permador (vanadium permendur)
or silicon iron pin armature (slug, plunger, core) of the
subminiature (micro) dc tubular plunger solenoid described in the
section that follows. To achieve the necessary force of plunger
expulsion, the coil is wound with silver wire. The prepositioning
distally of a debris trap is especially important when performing
an angioplasty on an artery with chronic total occlusion or a
graft, often a saphenous vein, that has become occluded.
[3213] In these situations, a principal concern is the release of
thromboemboli into the collateral circulation that had sustained
perfusion despite the lack of canalization or luminal obstruction
(see, for example, Meier, B. 1989 (reprinted 2005). "Angioplasty of
Total Occlusions: Chronic Total Coronary Occlusion Angioplasty,"
Catheterization and Cardiovascular Diagnosis 17(4):212-217; Kahn,
J. K. 1995 (reprinted 2005). "Collateral Injury by Total Occlusion
Angioplasty: Biting the Hand that Feeds Us," Catheterization and
Cardiovascular Diagnosis 34 (3): 65-66; Stone, G. W., Kandzari, D.
E., Mehran, R. Colombo, A, and 23 other authors 2005. "Percutaneous
Recanalization of Chronically Occluded Coronary Arteries: A
Consensus Document: Part I," Circulation 112(15):2364-2372; Stone G
W, Reifart N J, Moussa I, Hoye A, Cox D A, Colombo, A., Baim, D.
S., Teirstein, P. S., and 19 other authors 2005. "Percutaneous
Recanalization of Chronically Occluded Coronary Arteries: A
Consensus Document: Part II," Circulation 112(16):2530-2537).
[3214] Furthermore, chronic total occlusion notably affects the
coronary arteries, which grudging of working depth, discourage the
use of a transluminal device that requires significant anteport
extension longitudinal extension down the lumen. Accordingly, a
long filter of the kind proposed in 2003, which sought to combine
the strongest features of the best filters then on the market, at
the least demands modification for use in the coronary vessels. In
both edge and center-discharge barrel-assemblies, the recess or
silo for storing the trap-filter and its deployment and retrieval
or stowing solenoid is in the nose. The orientation of the recovery
electromagnet windings must afford the clearance required. A
combination-form muzzle-head, which requires an edge-discharge
muzzle-head, without a cabled device such as a rotational burr or
laser installed affords the bore or central channel for a
trap-filter.
[3215] When the central channel will be unavailable, the nose
isextended forward (distally) with the trap-filter recess located
to a side of the distal terminus of the central channel, or
nose-hole. The trap-filter deployment mechanism is disabled while
an installed laser is in use. Electrically operated radial
projection units, about the periphery of the muzzle-head can be
raised into working position during an angioplasty that is
performed with a unitary or bipartite angioplasty-capable
barrel-assembly where the apparatus remains independent of an
airgun unless and until the barrel-assembly is inserted into an
airgun to initiate stenting, and must therefore be controllable
from the onboard ablation and angioplasty control panel.
[3216] However, since trap-filter deployment can also prevent the
escape of a miniball whenever the magnetic field strength of the
recovery electromagnets must kept to a minimum,
angioplasty-incapable radial projection barrel-assemblies whether
used in the circulatory system may also justify the incorporation
of a trap-filter (Hussain, F., Rusnak, B., and Tam, J. 2008.
"Retrieval of a Detached Partially Expanded Stent Using the SpideRX
and EnSnare Devices--A First Report," Journal of Invasive
Cardiology 20(2):E44-E47). While discharge from a radial discharge
barrel-assembly would normally never strike the filter element
(mesh, membrane, basket), the risk of perforation is reduced by
making the mesh thicker and of a material intrinsically strong such
as nitinol.
[3217] For this reason, a second circuit independent of that used
to energize the thermal expansion wires is provided to allow the
deployment of the trap-filter independently of the radial
projection units, hence, during discharge as added protection
against the escape of a miniball into the bloodsteam. Since a
trap-filter reduces working depth when deployed, it is best stowed
when not required but readily deployable and retrievable without
the loss of debris. While a combination-form barrel-assembly that
incorporates or has temporarily inserted a laser has the ability to
disintegrate filter trapable debris, compulsory activation of the
laser whenever the side-sweepers are used is unacceptable as posing
a risk of perforation--not as destroying the filter it would then
supplant.
[3218] Trap-filter-deployment solenoid end-of-travel impact shock
as would tear the filter membrane and jolt the trap-filter so that
the outer nitinol ring kicked the lumen wall, is checked by an
elastomeric bumper-washer that surrounds the plunger exit orifice
to lightly clutch about the plunger and thus slow down and dampen
plunger ejection and spring return. Further to reduce the risk of
tears and kicking, one continuous strand of polyurethane suture is
diametrically wrapped entirely about the outside of the filter
membrane to begin and end at the head of the solenoid plunger.
[3219] A second such wrapping around or continuation with the same
strand at right angles to the first produces what appear to be four
struts. Even though the trap-filter-deployment solenoid is enclosed
within the ejection head as to release heat through the muzzle-head
nose-cap, the periods of energization (duty cycle) involved would
produce thrombogenic temperatures unless the bumper-washer
cooperated with the rest of the solenoid recess lining as a thermal
insulator, the solenoid is heat-sunk, and the cooling catheter is
used to prevent over-, or for that matter, under-heating.
[3220] VII2f(2)(a). Trap Filter Deployment and Retrieval
Mechanism
[3221] In minimally and fully ablation and angioplasty-capable
muzzle-heads, the use of a filter conforms to that practiced since
the 1970s. As shown in FIG. 50, thicker polyurethane or preferably
nitinol filter mesh membrane 170 typically has 120 micrometer pores
and is of a length that is recoverable or restowable into silo
recess 171 with additional space for retracting several miniballs,
albeit improbable of necessity. The trap-filter is deployed and
retracted or stowed by microminiature silver wire-wound push- or
punching-type solenoid 172 until the removal of current causes the
extension spring within solenoid 172 to reseat the armature or
plunger causing trap-filter 173 to retract or restow. Trap-filter
173 is separately deployable on demand with an independent switch,
but is automatically deployed with depression of the trigger switch
or activation of radial projection units 174 in FIGS. 49, 51 thru
63, 65, 66, 71, and 78.
[3222] On depressing trigger switch 175 in FIGS. 81 and 82,
discharge is deferred slightly, typically 5 milliseconds, by a
time-delay relay, the signal to filter deployment solenoid 173 sent
directly, whereas that for deployment of the radial projection
units, incorporated atherectomizer, or discharge following at that
interval delayed. With thermal expansion wire-lifted radial
projection units as shown in FIGS. 51, 52a, 53a, and 54 thru 56,
the heating interval delay intrinsic in the expansion wire
mechanism delays the projection of tool-insert holding and
lift-platform (tool holder, tool holding frame) 176 by a sufficient
interval for trap-filter 173 to have been deployed, so that trap
filter solenoid 172 is energized at the same time as is thermal
expansion wire 177.
[3223] Self-expanding trap filter mesh membrane 170 frame struts
178, ordinarily made of nitinol wire, allow 360.degree. apposition,
or contact of the filter periphery with the lumen wall preventing
bypass. To prevent the edges of filter mesh membrane 170 from
catching on the rim of the solenoid shaft upon retraction, the
filter struts must be peripheral to or outside the outer edge of
filter mesh membrane 170. In an ablation and angioplasty-capable
barrel-assembly used independently of an airgun, the trap-filter is
controlled from the on-board control panel with power drawn from
the inmate battery pack with circuitry likewise contained within
the slidable onboard power and control housing. By contrast, an
airgun-independent ablation or an ablation and
angioplasty-incapable barrel-assembly is used independently of an
airgun only occasionally.
[3224] VII2f(2)(b). Automatic Disabling of Implant-Discharge,
Radial Projection Units, and Turret-Motor
[3225] Barrel-assembly muzzle-head turret-motors are addressed
above and radial projection units below in respective sections of
like title. When used to perform an ablation or an angioplasty,
barrel-assemblies are usually disconnected from the airgun, making
accidental discharge impossible. An ablation and
angioplasty-capable barrel-assembly can be used for an ablation or
an angioplasty while engaged in the airgun; however, the hindrance
of remaining connected will almost always prompt disengagement.
With ablation and angioplasty-capable barrel-assemblies, the airgun
and barrel-assembly control panels are separate, minimizing the
risk of accidental discharge.
[3226] For use with minimally ablation or ablation and
angioplasty-capable barrel-assemblies, the airgun control panel
will usually include the ablation or angioplasty controls. Then to
prevent an accidental discharge, discharge is mechanically or
electrically disabled, the latter by switching off the trigger
switch, for example. Such disconnection can be switched
automatically upon use of the ablation or angioplasty controls.
Enabling discharge during ablation or angioplasty then necessitates
that disabling this automatic disconnection. If an assistant is
assigned to operate the airgun while an ablation or ablation and
angioplasty-capable barrel-assembly remains engaged therein, then a
switch on the barrel-assembly control panel is used to disable the
ablation or angioplasty control panel
[3227] For freedom of movement, an ablation or ablation and
angioplasty-capable barrel-assembly used while engaged in the
airgun would normally be connected to a modified air pistol
positioned behind the barrel-assembly hand-grip. As the apparatus
is then held by the hand-grip with angioplasty control panel on its
top side, the chance of an accidental discharge is slight even
without the safety engaged or any magazine clip removed from the
air pistol chamber. If unintentionally deployed during movement of
the barrel-assembly, a shaving or abrading cutting tool-insert such
as described below in the section entitled Radial Projection Unit
Tool-inserts could injure the lumen wall.
[3228] To reduce the risk of scrapes (abrasions), gouges
(punctures, perforations), or incisions, radial projection unit
tool-inserts must be kept retracted whenever the barrel-assembly is
resituated. To avert human error that would allow tool-inserts to
remain in the raised position, the units are controlled as
`normally off` or retracted, requiring sustained depression of the
control switch to remain raised. To this end, the ablation or
angioplasty control panel spring-return push-to-actuate electrical
switches, generally two, are supported by lift-platforms that are
kept under the continuous downward (medial, retractive) urging of a
strip-spring that to overcome requires intentional energization of
the lifting mechanism by depressing the control switch. Multiple
electrical units can be controlled, hence, disabled together
according to how these are patched at the control panel to a given
push-switch or to which preset combination of units the push
control is switched.
[3229] Push-to-actuate control eliminates the need for logic
circuitry, motion sensors, warning signals and switches to override
these when the units are to remain projected during movement. The
turret-motor motional control circuit incorporates a
circuit-breaker to turn off the turret-motor if overloaded, which
risks heat, mechanical, and in a blood vessel, thrombogenic injury.
Deployment of the trap-filter can be appropriate during angioplasty
or discharge; unsuited to automatic disabling, it is left
discretionary except on energization of the laser in a
combination-form barrel-assembly when the filter membrane would be
destroyed. The filter deploying solenoid is disconnected when the
laser in turned on. With a commercial laser, this cutout must be
added to the laser on-switch.
[3230] VII2f(3). Blood-Tunnels
[3231] Blood-tunnels are tubes within the barrel-catheter that
inlet at a point at the periphery of the barrel-catheter, and
closing off the space these contain from the surrounding space
within the barrel-catheter, or peribarrel space, course
longitudinally at an angle or diagonally, to outlet at an arcuate
or circumferentially removed end-point distal to the inlet. The
blood able to pass through a blood-tunnel will largely depend upon
its internal diameter, which thus becomes a factor in spacing the
barrel-tubes by means of centering devices within and sizing the
barrel-catheter. By and large, blood-tunnels gain significant
effectiveness in large diameter barrel-assemblies. The barrel
catheter is usually smaller in diameter than the muzzle-head,
reducing the need to provide passages to allow oxygenated blood to
pass the endoluminal component equivalent to the side or perfusion
holes in conventional catheters.
[3232] The circumferential position, orientation, as well as the
number of blood-tunnels can be used to affect stiffness. As do the
number of centering devices and whether these are glued to the
barrel-tubes, blood-tunnels also serve as tube polymer nonintrinsic
barrel-catheter flexibility (bendability, trackability) altering
elements and can be used to adjust barrel-catheter flexibility
along the proximal or intermittent portions. In the proximal
segment to remain extracorporeal, stiffening reduces drooping and
kinking at the entry portal; however, stiffening of the
intracorporeal length has little utility and is likely to produce
stretching if not snagging injury, although these are avoidable by
wetting stiffer sections with one of the lubricants specified in
the section above entitled Insertion Tool Structure.
[3233] Blood-tunnels situated to one side of the barrel-catheter
will promote flexing in the diametrically opposite direction.
Provided the barrel-catheter has clearly visible contrast markings
to indicate its rotional angle, this can improve trackability
through a tighter curve. As shown in FIG. 41, blood tunnels are
provided at opposite angles on either side of the barrel-catheter.
Opposing angles thus generally make little if any difference for
flow-through whether the barrel-assembly is advanced or withdrawn
in antegrade or retrograde flow. Referring now to both FIGS. 39,
42, and seen in detail in FIG. 41, the flow of blood is antegrade
from left to right, and the direction of miniball discharge,
likewise left to right, is indicated with arrows, making the
proximal inlets 93 of blood-tunnels 96 distinguishable from the
distal outlets 94.
[3234] Barrels 74 in FIG. 41 pass through the barrel-tube holes 91
shown in FIG. 42 in the centering device 95 containing gas pressure
relief holes 92 and central aperture 90 through which wires 97 in
FIGS. 41, 72, 74, and 75 for the electromagnets, turret-motor, and
radial projection units if present pass. The incorporation of
blood-tunnels may necessitate the use of a larger diameter
barrel-catheter, with the consequence that the flexibility of the
barrel-assembly will be reduced both as widened and as
incorporating blood-tunnels. While a barrel-catheter that is narrow
may be increased in diameter to allow the incorporation of
blood-tunnels, it must not exceed the muzzle-head in diameter, and
the muzzle-head is not increased in diameter.
[3235] Larger diameter multibarrel radial discharge
barrel-assemblies can incorporate both blood-grooves, shown as 66
in FIGS. 38 and 40, and blood-tunnels, shown as 96 in FIGS. 39, 41,
and 42 within barrel-catheter 72, these elements described below.
While a monobarrel radial discharge barrel-catheter can be small
enough in outer diameter to serve as a kind of `guidewire` for
follow-on devices, devices that use guidewires normally serve
functions that precede rather than succeed stenting; however, where
the muzzle-head passes readily through the lumen as to dispel
concerns about stretching, dissection, or perforation, the
muzzle-head can be used to implant miniballs upon withdrawal.
[3236] Depending upon the angle at which the blood-tunnel tubes
course through the barrel-catheter and the material or materials of
which the blood-tunnel tubes are made, the blood-tunnels allow some
transmission of the pulse through the barrel-catheter. Made of more
rigid materials, the blood-tunnels can, according to number and
spacing, also act as structural buttresses to stiffen the
barrel-catheter. Placing blood-tunnels in longitudinal sequence
along one radius of the barrel-catheter, for example, will bias the
bendability of the barrel-assembly away from that direction toward
the perpendicular or normal direction. Angular uniformity in the
stiffness of the barrel-assembly thus requires a circumferentially
complementary and balanced distribution of blood-tunnels.
[3237] When made of a pliant material or materials, such as vinyl,
and bonded by means of an adhesive to the wall of the
barrel-catheter with acutely angled mitered ends, the blood-tunnels
can course in substantially adjacent relation to the concave
surface of the barrel-catheter. Made of rigid material, such as
polystyrene or high density polyethylene or polypropylene, the
blood-tunnels are straight as to appear geometrical cords in
cross-section, and buttress the wall of the barrel-catheter, making
it stiffer. With the barrel-catheter and barrel-tubes bonded to the
centering devices, no significant increase in stiffness is realized
by coursing the blood-tunnel tubes through and bonding these to the
centering devices.
[3238] In the portions of the barrel-assembly to remain outside of
the patient, the elimination of nonfunctional bends that detract
from control over the rolling resistance to the miniballs is
necessary to achieve accurate exit velocity and impact force. Thus,
when the materials of the barrel-catheter and barrel-tubes are
highly pliant, the incorporation of blood-tunnels in the
barrel-catheter serves to minimize flexion in the proximal portions
of the barrel-assembly. By comparison, in the distal portions of
the barrel-assembly introduced into the patient, flexibility
sufficient to track anatomical bends with little resistance is
preferable.
[3239] Accordingly, blood-tunnel tubes are not incorporated toward
the fore; however, the flexibility sought for this portion
recommends the use of centering devices that allow the diameter of
the barrel-catheter to be smaller, and this in itself will allow
some passage of the pulse up to and through the blood-grooves in
the sides of the muzzle-head. The elimination of centering devices
in the distal portions of the barrel-assembly does not negate the
need for a peribarrel space sufficient in volume to relieve the
pressure of discharge so that no gas will be ejected into the
bloodstream. Since the barrel-catheter must accommodate this need
for sufficient peribarrel space, a barrel-catheter of minimum
internal diameter must be provided. The omission of centering
devices thus has only the result of the dropping of the
barrel-tubes to the floor of the barrel-catheter.
[3240] VII2f (4). Incorporation of a Bounce-Plate into Radial
Discharge Barrel-Assemblies
[3241] The value in a proximad redirection or trajectory reversal
capability pertains primarily to advanced cases of collapse or
stenosis of the trachea with its structured lumen wall that
includes cartilage rings and ligaments necessitating the accurate
placement of implants. Other ductus are not this structurally
differentiated, so that the insertion of implants to given
trajectory end-points or target locations can usually proceed
unidirectionally with uniformly distad or forward-inclined
trajectories and without the need for reversal to proximad or
backward-inclined trajectories. To minimize the risk of injury,
bounce-plate attachments and mechanisms made as part of the
barrel-assembly must be as small and unobtrusive with rounded off
edges as possible.
[3242] Furthermore, since for a given number of barrel-tubes, a
radial discharge barrel-assembly should achieve minimization in the
outer diameter of the muzzle-head, and the addition of
bounce-plates, requiring the muzzle-ports to be recessed, would add
diameter if within, and would be likely to cause scraping injury to
the larynx or lumen wall if mounted to the outside of the
muzzle-head. In a multiple discharge barrel-assembly, these
consequences are unacceptable. For this reason a radial discharge
barrel-assembly with an attached or permanent bounce-plate should
be avoided. However, if equipped with an enclosed and nonprotrusive
bounce-plate that can be deployed from outside the body, as
described above in the sections entitled Extracorporeally
Deployable Bounce-plate with Fixed Rebound Angle and
Extracorporeally Deployable Bounce-plate with Adjustable Rebound
Angle, a single barrel radial discharge barrel-assembly may be
usable in the trachea of a tiny dog, for example.
[3243] Even the introduction and withdrawal of a simple pipe
barrel-assembly provided with a protective rubber surround
extension at the distal end through the larynx must be performed
with caution. Requiring to avoid the need for multiple withdrawals
and reentries that increase the chances for entry wound
complications, a radial-discharge barrel-assembly configured for
use in the circulatory system would demand remotely deployable
bounce-plates. Of little value, these would add to the cost. The
essential structural uniformity or homogeneity of the average lumen
wall obviates the need for such a capability. The structured
character of the tracheal lumen is larger than the structurally
undifferentiated lumens of vessels and ducts, making observation of
the tracheal lumen more important and less difficult.
[3244] The usefulness of radial discharge barrel-assemblies capable
of reversing the direction of the trajectory in the vascular tree
or in ducts, whether provided in a single embodiment or by changing
to either of two embodiments, is thus recognized as feasible but
anatomically unjustified. In the airway of a small dog or human
neonate, such a radial discharge barrel-assembly could achieve
precise aiming only tediously and laboriously, while in the
vascular tree, no such reverse aiming capability is necessary. For
these reasons, the incorporation of means for reversing the
direction of the trajectory in radial discharge barrel-assemblies
other than in a radial discharge monobarrel for the purpose stated
is discounted.
[3245] VII2f(5). Use of Minimally and Fully Angioplasty-Capable
Radial Discharge Barrel-Assemblies
[3246] A minimally ablation or ablation and angioplasty-capable
barrel-assembly with an embolic filter and radial projection units
in the muzzle-head includes angioplasty components only to the
extent needed for implantation discharge without complications.
Unlike a fully capable barrel-assembly, it is not intended for
disengagement from the airgun as an independent apparatus for free
manipulation and cannot be used to perform an angioplasty when
disconnected from an airgun. Drawing power and control from the
airgun through end-plate connecting terminals such as shown in FIG.
72 and not ordinarily equipped with a side-port or side-socket, it
is closed off for attaching a supportive device such as a gas
cylinder or laser cable and is less versatile than a fully
angioplasty-capable barrel-assembly.
[3247] Minimally and fully ablation and/or angioplasty-capable
barrel-assemblies may be required to lay down a pattern of
miniballs placed at millimetric distances along the lumen wall, and
both barrel-assemblies and radial projection catheters usually have
embolism-preventing heat-windows as addressed above in the section
entitled Thermal Conduction Windows (Heat-windows) and Insulation
of the Muzzle-head Body in Minimally or Fully Thermal Ablation and
Thermal Ablation and Angioplasty-capable (Independently Usable)
Barrel-assemblies and radially directed working tools as addressed
above in the section entitled Radial Projection Units which must be
passed over the lumen wall at a controlled rate. The use of these
will generally require advancement or retraction of the
barrel-assembly at a uniform rate by a semiautomatic positional
control system, as addressed below in the section entitled Linear
Positioning Stage or Table Airgun Mount.
[3248] Providing side-ports or side-sockets negating the economic
advantage in producing a less than fully angioplasty-capable
barrel-assembly, to connect an ancillary catheteric or cabled
device necessitates disengaging the barrel-assembly from the airgun
to gain access to a socket or side-port in the proximal end-plate.
Disconnection from the airgun is also necessary to add a radial
projection catheter. Engagement in the airgun allows precise
transluminal positioning with the airgun linear positioning stage
and rotary movement with the turret-motor but hinders freedom of
movement. In more unpredictable and precarious situations,
barrel-assemblies for use in blood vessels should incorporate an
array of potential responses to possible midprocedural
eventualities.
[3249] If bipartite, radial projection unit tool-inserts of any
kind can be introduced using the barrel-catheter as a guide wire at
any time during the procedure without requiring withdrawal.
Unforeseeable eventualities aside, angioplasty-capable
barrel-assemblies, functional apart from the airgun for every
purpose but implantation discharge, with remotely (hand-grip)
controllable radial projection units, deployable and retractable
run-ahead trap-filter (embolic filter), heat-windows, and
side-socket for connecting different fluid and electrical
attachments, can be preconfigured for a specific procedure.
Muzzle-head radial projection unit tool-inserts, for example, can
be chosen for the purpose at hand, and the use of a
combination-form barrel-assembly allows the prepositioning of a
rotatory burr or excimer laser, for example.
[3250] Because a size-matched combination-form radial projection
catheter can be introduced at any time, response to almost any
contingency is possible. The incorporation of radial projection
unit blank (push-arm, shoe) tool-inserts, as addressed below in the
section entitled Radial Projection Unit Tool-inserts, allows the
muzzle-head to be brought into flush relation with the side to be
implanted without the application of an extraluminal force field or
significantly adding to the cross-sectional area of the lumen that
is obstructed. When provided about its entire circumference, the
muzzle-head can restrain the lumen wall all around at the peak
systolic diameter while suspending itself axially without
obstructing the flow of blood, which passes around and/or through
the tool-inserts.
[3251] This suppresses pulsation over the segment under treatment
when the muzzle-head need not be brought into adjacent abutment
against the lumen wall. The passage of blood is also aided by
incorporating blood-grooves and blood-tunnels as addressed below in
the section entitled Monobarrel Radial Discharge Muzzle-head. In
most instances, implantation is facilitated if not enabled by
suppressing rather than attempting to accommodate an interfering
pulse or intrinsic motility. When it can be assumed that sufficient
accuracy will be achieved manually without suppressing relative
movement between the exit port and the target location, the manual
discharge of miniballs in an artery is more accurate if the
muzzle-head is positioned during the systoles, during which phase
the expansion in lumen diameter expedites this resituation and
reduces the risk of ischemia by moving blood past the
muzzle-head.
[3252] Discharge is then effected with the artery relaxed at the
end of the diastoles. Manual control is also aided through the use
of medication to slow or temporarily arrest autonomic motility, as
addressed below in the section entitled Motional Stabilization of
the Implant Insertion Site. Even though ideally the muzzle-head
lightly contacts the lumen wall during discharge, the pressurized
air forced before the discharging miniballs must be given a path of
least resistance to prevent air from being forced into the
bloodstream upon discharge. At the same time, to prevent the
back-flow into the barrel ports of blood when the muzzle-head is
immersed in the bloodstream, resistance must be posed to the
displacement of the air in the muzzle. In other words, the flow of
gas must be biased in favor of nondisplacement from without while
at rest and in favor of pressure diversion back into the
barrel-assembly under conditions of the sudden pressurization of
expulsion.
[3253] The volume of air in the barrel-assembly and chamber,
together airtight except through the barrel, is constant. The
higher pressure of the blood and angle of entry make complete
prevention of blood backflow through the muzzle-ports at the moment
of immersion difficult without barricading the muzzle-ports.
Because the gas pressure pressure diversion channels and relief
space must become completely filled with blood before resistance to
the passage of gas equals that presented by the column of blood at
the muzzle-ports, blockage for this reason midprocedure is
unlikely. Should the mechanism become fouled, the barrel-assembly
is withdrawn and purged with pressurized distilled water. In most
instances, because the barrel-assembly is airtight, this is
accomplished by placing a finger over the muzzle-ports facing
upwards and thus not allowing air to be displaced by blood.
[3254] When the placement of the muzzle-ports does not allow these
to be blocked to the air with a fingertip, the muzzle-head is
dipped into distilled water so that the muzzle-ports are filmed
over by surface tension. The muzzle-head is then stored in a
freezer. To be certain that the film does not break by cold
contracture and is sufficiently thick, dipping and freezing may be
repeated several times. Upon insertion in the bloodstream, an
interval is allowed for the temperature of the blood to melt the
film of ice and the muzzle-head to assume body temperature. In an
embodiment that includes electrically operated radial projection
units, the thermal expansion wires used to raise the tool-insert
holding and lift platform can be sent current to accelerate
melting. Whether the brushes remain deployed during transluminal
movement to the diseased portion of the ductus is at the discretion
of the operator.
[3255] Initial transluminal movement is usually to a point beyond
the segment of the ductus to be treated with the procedure carried
out in withdrawal with movement over larger distances directly
manual, over small distances by manual control of the linear
positioning table stepper motor, and discharge over lesions by
manual direction of automatic sequences. Once immersed in the
bloodstream, the airtightness of the barrel-assembly prevents the
inflow of blood. A simple pipe barrel-assembly is not for use in
small diameter lumina as risking injury and is additionally
unsuited to use in the circulatory system as lacking internal paths
for averting gas expulsion at the muzzle exit-ports or exit-holes
with consequent embolization. The barrel-tubes in a radial
discharge barrel-assembly suitable for use in the vascular tree are
perforated, removing barriers within the spaces defined by the
different tubes within the barrel-assembly.
[3256] The perforations present no burrs or irregularities on the
inner surface of the barrel-tubes, which must be smooth. The air
throughout the barrel-assembly now in communication or effectively
continuous, the displacement of air anywhere within this space is
minimally resistant to internal movement or redistribution. This
diverts expulsive gas within the muzzle-head before exiting and
minimizes recoil, thus both averting injury to the vessel and the
dislodging of miniballs remaining on the rotary magazine clip.
[3257] As seen in FIGS. 48, 49, 65, and 66, gas pressure
equalization (pressure relief, pressure diversion) channels 226 are
drilled through the muzzle exit ports creating a path from each to
the central channel The gas pressure ahead of the discharging
miniballs is thus bled off or diverted to the central channel as
the path of least resistance compared to introfusion into the
blood. Gas returned with sufficient force that it would jerk the
barrel-tubes is released through an elastomeric membrane slit valve
in the end-plate. The outflow of these pressure diversion channels
is directed proximally or backwards to the canal formed by their
convergence which is continuous with the central canal amid the
barrel-tubes.
[3258] Following puncture and expansion of a vessel, the
heparine-saline solution-wetted muzzle-head is introduced and
advanced to the sites slightly short of preceding angioplastic
treatment. Discharged at an acute angle, the shots then come to
rest beneath the atheroma and removed plaque. The muzzle-head is
chosen in a size equal or slightly larger in diameter than the
internal diameter of the segment of the vessel short of the area to
receive the miniball implants by the length of the trajectory.
Since the placement of a conventional intraluminal stent may
squeeze away remaining plaque, the preliminary angioplasty should
be thorough. During angioplasty, rotation expedites aiming a
heat-window radial projection unit tool-insert at an eccentric
lesion.
[3259] Since an angioplasty is completed before ferromagnetic
implants have been introduced, there are not yet implants present
that the field strength of the windings associated with thermal use
might reposition or extract. Disruption thus must, however, be
considered in a retreatment that uses the means described. The
rotatory use of the turret motor to direct a heat-window that is
heated by passing current through one or both recovery
electromagnet windings, which are seldom needed for recovery other
than during discharge, remains enabled, allowing treatment of an
eccentric lesion. Radial projection unit tool-inserts, to include
those heat radiating, are powered independently of the other
components in the barrel-assembly. When, however, the heat-window
is heated with the winding of the turret-motor itself, the rotatory
use of the motor is disabled.
[3260] During discharge, rotation is used to change the aiming
point of a single, a particular, or radially asymmetrical set of
muzzle-ports, or to rotate the tractive electromagnets to recover a
mispositioned or stray miniball. The trap-filter shares with the
turret-motor in its rotatory mode of operation use in both
angioplasty and discharge. During angioplasty, the trap-filter
stops potentially embolizing debris from being carried downstream,
whereas during discharge, it affords the same protection against
escaped miniballs, although the level of protection provided by the
recovery electromagnets will usually prove sufficient. When it does
prove sufficient, and additional protection is considered redundant
if not an impediment, the trap-filter is not deployed.
[3261] VII2f(6). Ablation and Angioplasty-Incapable Barrel-Assembly
Controls on the Airgun
[3262] Airgun controls are mounted to airguns and barrel-assembly
controls to barrel-assemblies, the exception being that pistols and
dedicated airguns meant for use with minimally ablation or ablation
and angioplasty-capable barrel-assemblies, which are used only
while inserted in the airgun, generally include the controls for
ablation or angioplasty on the airgun. The discharge controls
required on the airgun respond to the exit velocity control points
in the airgun, so that modified commercial pistols lack controls
for adjusting the current to a plunger solenoid used in dedicated
interventional airguns as a triggering mechanism, for example.
Duplicate controls are exceptional, result when minimally-capable
barrel-assemblies are provided with onboard controls, which does
not involve a bulky duplication in battery packs.
[3263] Such results from pairing a modified air pistol having
thermoplasty and other controls meant for use with a minimally
ablation or ablation and angioplasty-capable barrel-assembly with
an ablation or ablation and angioplasty-capable barrel-assembly
that is self-contained for airgun-independent use. The controls for
modified commercial air pistols are mounted to the hand-open side
of the pistol-grip battery pack and control electronics downward
extension, while those for dedicated interventional airguns are
mounted to the airgun enclosure or cabinet. Lacking ablation or
angioplasty capability, the controls are limited to those governing
discharge.
[3264] Miniball recovery related to discharge rather than to
ablation or angioplasty, pistols meant for use only with ablation
and angioplasty-incapable barrel-assemblies require potentiometers
to adjust the current through the recovery electromagnet or magnets
for the purpose of adjusting the magnetic field strength. A simple
pipe barrel-assembly is usually provided with one such magnet,
while a radial discharge ablation or ablation and
angioplasty-capable barrel-assembly is provided with two. Radial
discharge ablation or angioplasty-incapable barrel-assemblies
equipped with an embolic trap-filter as an additional safeguard
against the escape of a miniball rather than to catch fractured
plaque debris also require a solenoid control as addressed above in
the section entitled Trap-filter Deployment and Retrieval Mechanism
to deploy and retract the filter.
[3265] Pistols meant for use with both ablation or
angioplasty-incapable and minimally capable barrel-assemblies must
include the additional controls required for radial projection
units, embolic trap-filter, and use of the windings in the
muzzle-head as thermoplasty heating elements. Modified air pistols
are not normally used with ablation or ablation and
angioplasty-capable barrel-assemblies. Meant for use independently
of the airgun, the latter have ablation or angioplasty controls
mounted to a power and control housing which can be
hand-grip-configured to contain a battery pack that is lacking in
incapable and minimally capable barrel-assemblies.
[3266] VII2g. Minimally Ablation or Ablation and
Angioplasty-Capable Barrel-Assemblies
[3267] Minimally ablation or ablation and angioplasty-capable
barrel-assemblies are differentiated from other types of
barrel-assembly in the section above entitled Types of
Barrel-assembly. Compared to an ablation or ablation and
angioplasty-capable barrel-assembly, the muzzle-head is
substantially the same but is likely to incorporate fewer tissue
reduction features, while the proximal engagement components of the
barrel-assembly must be distinct. Accordingly, muzzle-heads for
both types are addressed in this section. This type incorporates
any or all of the components used to accomplish an ablation or an
angioplasty, to include radial projection units and trap-filter,
but is not configured for use independently of an airgun.
[3268] Without a side-socket, as addressed below in the section
below entitled Barrel-assembly Side-socket, a minimally ablation or
ablation and angioplasty-capable barrel-assembly must be removed
from the airgun to allow the insertion of a cooling or medication
delivering catheter into the central canal or a barrel-tube through
the proximal terminal plate (end-plate). Since this breaks the
electrical connection to its electrical components, it must then be
reconnected to the airgun power supply through a socket mounted to
the outside of the airgun enclosure or connected to an alternative
source of power.
[3269] VII2g(1). Minimally Thermal Ablation or Angioplasty-Capable
Barrel-Assemblies
[3270] As addressed here, thermoplastic ablation is intended to
apply to vulnerable plaque. Calcified plaque and minimally inflamed
endothelium are not to be treated thus as substantially stable,
nonvulnerable, and treatable with oral medication. Discretionary
searing of vulnerable plaque is intended to eliminate detritus
(fibrin, necrotic atheromatous core, foam cells, cholesterol
clefts, and thrombus (see, for example, section 4d(2) entitled
Ductus Wall Tumefacients and Sangiorgi, G. and Colombo, A. 2003.
"Embolic Protection Devices," Heart (London, England)
89(9):990-992) liable to enter the lumen. All apparatus described
herein include heat and Peltier device cooling on-off switches
adjacent to heating plates to allow quick heating and cooling so
that heat does not continue past the vulnerable plaque once
traversed. Searing is with fluoroscopic or computer tomographic
guidance and a contrast media coated muzzle head.
[3271] Contrast dispersed in the bloodstream must not be implicated
in nephrophathy or have such tendency ameliorated (see, for
example, Zhang, J. Z., Kang, X. J., Gao, Y., Zheng, Y. Y., Wu, T.
T., and 6 others 2017. "Efficacy of Alprostadil for Preventing of
Contrast-induced Nephropathy: A Meta-analysis," Scientific Reports
7(1):1045; Mohammadi, M., Hajhossein Talasaz, A., Alidoosti, M.,
Pour Hosseini, H. R., Gholami, K., Jalali, A., and Aryannejad, H.
2017. "Nephroprotective Effects of L-Carnitine against
Contrast-Induced Nephropathy in Patients Undergoing Percutaneous
Coronary Intervention: A Randomized Open-labeled Clinical Trial,"
Journal of the Tehran Heart Center 12(2):57-64; Ye, Z., Lu, H., Su,
Q., Guo, W., Dai, W., Li, H., Yang, H., and Li, L. 2017. "Clinical
Effect of Trimetazidine on Prevention of Contrast-induced
Nephropathy in Patients with Renal Insufficiency: An Updated
Systematic Review and Meta-analysis," Medicine (Baltimore, Md.)
96(9):e6059; Ye, Z., Lu, H., Guo, W., Dai, W., Li, H., Yang, H.,
and Li, L. 2016. "The Effect of Alprostadil on Preventing
Contrast-induced Nephropathy for Percutaneous Coronary Intervention
in Diabetic Patients: A Systematic Review and Meta-analysis,"
Medicine (Baltimore, Md.) 95(46):e5306; Golshahi, J., Nasri, H.,
and Gharipour, M. 2014. "Contrast-induced Nephropathy: A Literature
Review," Journal of Nephropathology 3(2):51-56; Weikl, A. and
Hubmann, M. 1982. "A Survey of Contrast Media Used in Coronary
Angiography," Cardiovascular and Interventional Radiology
5(3-4):202-210). In any barrel-assembly for use in the arterial
tree, the preliminary elimination of fibrous caps and subjacent
detritus prevent a liberation of potentially embolizing debris when
the muzzle-head, usually unheated during discharge, makes contact
with the lumen wall (see, for example, Finet, G., Ohayon, J.,
Rioufol, G., Lefloch, S., Tracqui, P., Dubreuil, O., and Tabib, A.
2007. "Morphological and Biomechanical Aspects of Vulnerable
Coronary Plaque," Archives des Maladies du Coeur et des Vaisseaux
100(6-7):547-553; Bentzon, I. F. and Falk, E. 2001. "Coronary
Plaques Calling for Action--Why, Where and How Many?," European
Heart Journal Supplements 3(Supplement I):13-19).
[3272] However, the disease process and inflammation of
atherosclerosis, if not the frank atheromatous lesions it produces
where the arterial tree is wider in caliber or bifurcated, for
example, extend throughout the larger gauge portions of the
arterial tree, the systemic nature of endothelial activation,
dysfunction, and atherosclerosis apparent from any of several
perspectives (see, for example, Chu, D., Bakaeen, F. G., Wang, X.
L., Dao, T. K., LeMaire, S. A., Coselli, J. S., and Huh, J. 2008.
"The Impact of Peripheral Vascular Disease on Long-term Survival
after Coronary Artery Bypass Graft Surgery," Annals of Thoracic
Surgery 86(4):1175-1180; Ridker, P. M. and Silvertown, J. D. 2008.
"Inflammation, C-reactive Protein, and Atherothrombosis," Journal
of Periodontology 79(8 Supplement):1544-1551; Mora, S. and Ridker,
P. M. 2006. "Justification for the Use of Statins in Primary
Prevention: An Intervention Trial Evaluating Rosuvastatin
(JUPITER)--Can C-reactive Protein be Used to Target Statin Therapy
in Primary Prevention?," American Journal of Cardiology
97(2A):33A-41A; Toutouzas, K, Drakopoulou, M., Mitropoulos, J.,
Tsiamis, E, Vaina, S, and 4 others 2006. "Elevated Plaque
Temperature in Non-Culprit De Novo Atheromatous Lesions of Patients
with Acute Coronary Syndromes," Journal of the American College of
Cardiology 47(2) 301-306; Bhatt, D. L. and Topol, E. J. 2002. "Need
to Test the Arterial Inflammation Hypothesis," Circulation
106(1):136-140; Heras, M. and Chamorro, A. 2000. "Atherosclerosis:
A Systemic Condition that Requires a Global Approach," European
Heart Journal 21(11):872-873; Eagle, K. A., Rihal, C. S., Foster,
E. D., Mickel, M. C., and Gersh, B. J. 1994. "Long-term Survival in
Patients with Coronary Artery Disease: Importance of Peripheral
Vascular Disease. The Coronary Artery Surgery Study (CASS)
Investigators," Journal of the American College of Cardiology
23(5):1091-1095; Balas, P. and Pangratis, N. 1990. "Panarterial
Ultrasonography. A Non invasive Evaluation of the Peripheral
Arterial System," International Angiology 9(1):4-7; Sumner, D. S.
1989. "Non-invasive Assessment of Peripheral Arterial Occlusive
Disease," in Rutherford, R. B. (ed.), Vascular Surgery, 3d Edition,
pages 61-111, Philadelphia, Pa.: W. B. Saunders; Carter, S. A.
1969. "Clinical Measurement of Systolic Pressures in Limbs with
Arterial Occlusive Disease," Journal of the American Medical
Association 207(10): 1869-1874).
[3273] That the chronic inflammation of endothelial activation is
systemic recommends the systemic and targeted use of statins and
conservative use of atherectormy or thermal angioplasty, for
example, as limited to plaque. As addressed above in the
introductory sections and that entitled Cooperative Use of
Impasse-jackets in Pairs and Gradient Arrays, paired
impasse-jackets allow targeting a statin, for example, to a
delimited segment of an artery, for example, at a high
concentration, at the same time that a background dose of the
statin is administered conventionally. As addressed above in the
section entitled Preliminary Description of the Invention, and
others, the elimination of plaque is a factor in promoting recovery
to normal function.
[3274] Where the primary drug is best circulated but uptake by the
target organ or tissue is insufficient and located too deeply for
release from a transdermal patch to deliver the dose sought deeply
or quickly enough, the directly targeted delivery to the tissue or
organ to can be accomplished through placement of a local jacket or
nonjacketing side-entry connector, if necessary, with a small dose
of dimethyl sulfoxide (DMSO) to expedite uptake. When a surface
port is already in use, local delivery is through a ductus
side-entry jacket or nonjacketing side-entry connector. Several
combinations for systemic and pipe-targeted delivery are possible.
When no surface port is present and the use thereof felt not
warranted for this limited purpose, the infused drug to be
circulated and not just taken up by a target organ or tissue can,
for example, be introduced in part as a ferrofluid wherein the drug
is carried by superparamagnet iron oxide nanoparticles with the
jacket or connector inclusive of a magnetized layer.
[3275] The capability to perform a preemptive eradication of the
potentionally thromboembolizing lining of a more affected lumen
thus has protective value. Such a barrel-assembly has a minimal
thermoplasty capability. As applied here, thermal angioplasty or
thermoplasty, addressed below in the section entitled Thermal
Ablation and Angioplasty- (Lumen Wall Priming Searing- or Cautery-)
Capable Barrel-assemblies, seeks to systematically and preemptively
destroy vulnerable plaque through a leading end searing (cautery,
electrocautery, singeing) of the endothelium upon contact with the
heated muzzle-head, which unlike the use of a balloon, eliminates
the vulnerable plaque as a threat postprocedurally.
[3276] An initial heating pass of the muzzle-head can be
accomplished perfunctorily as a prophylactic or preventive measure
when the presence of vulnerable plaque is suspected without having
been confirmed. When possible, the thermoplasty is accomplished in
the same pass as the other therapeutic action is applied. A
prepositioned stent-jacket or shield-jacket containing sufficient
continuous ferrous material can be noninvasively heated by placing
the patient in a radiofrequency alternating magnetic or
electromagnetic field, but thorough coverage must be transluminal
or catheteric. Another reason for incorporating a nose
radiofrequency probe or thermoplasty window is to fuse any
ductus-intramural tunics confirmed through imaging to have
delaminated, although this is better accomplished with the aid of a
bonding agent injected by tool-insert injectors in a more capable
barrel-assembly.
[3277] Compression during the application of heat is obtained by
prepositioning the stent-jacket and steering the muzzle-head
against the lumen wall with the aid of 1. Blank tool-inserts on the
opposite side used as push-arms, 2. An extracorporeal electromagnet
and/or 3. An oversized muzzle-head with blood bypass means in the
form of blood-tunnels, blood-grooves, and/or a patent central
channel (see, for example, Barry, K. J., Kaplan, J., Connolly, R.
J., Nardella, P., Lee, B. I., Becker, G. J., Waller, B. F., and
Callow, A. D. 1989. "The Effect of Radiofrequency-generated Thermal
Energy on the Mechanical and Histologic Characteristics of the
Arterial Wall in Vivo: Implications for Radiofrequency
Angioplasty," American Heart Journal 117(2):332-341; Fram, D. B.,
Gillam, L. D., Aretz, T. A., Tangco, R. V., Mitchel, J. F., and 6
others 1993. "Low Pressure Radiofrequency Balloon Angioplasty:
Evaluation in Porcine Peripheral Arteries," Journal of the American
College of Cardiology 21(6):1512-1521).
[3278] To eliminate the need for withdrawal and reentry, thermal
angioplasty must be performed with a minimal or fully ablation or
ablation and angioplasty-capable barrel-assembly. Numerous means
for accomplishing thermoplasty include an inmate radiofrequency
probe or laser at the nose. Others are heatable motor and recovery
electromagnet windings and connectable sources of hot gas-heated
heat-windows, as described below in the section entitled Thermal
Conduction Windows (Heat-windows) and Insulation of the Muzzle-head
Body in Thermal Ablation or Thermal Angioplasty-capable
Barrel-assemblies. Still others are an excimer laser or rotational
atherectomy cutter installed in the central channel of a
combination-form barrel-assembly (addressed below in the section
entitled Combination-form Barrel-assemblies, et sequens).
[3279] Regardless of whether the heat-window is heated by the
winding inside it or by connection to the hot air outlet of a
vortex-tube cold air gun, for example, both the temperature and
time of contact of the heat-window with the plaque are critical.
Precise timing can be attained by insertion of the barrel-assembly
in a an airgun mounted upon or to a separate linear stage. The
recovery and turret-motor electromagnet windings can, however, be
heated, such as to warm a coating of heat-activated tissue bonding
agent applied to miniballs discharged through barrel-tubes kept
chilled by a cooling catheter as the muzzle-head is withdrawn, as
indicated above in the section entitled Circumstances Dissuading or
Recommending the Application of Stays.
[3280] Cryoplasty seeks primarily to reduce intimal hyperplasia
following the angioplasty. Cryoplasty is briefly addressed above
under the section entitled Turret-motor Operational Modes. There
are essentially three classes of barrel-assembly for use in the
arterial tree: ablation or angioplasty-incapable, which are used
only while engaged in the airgun and lacking means for thermoplasty
are limited to treatment where a precautionary angioplasty has been
discounted; minimally-capable, which incorporate a nose heat-window
and are seldom if ever disengaged from the airgun to perform an
angioplasty; and ablation or ablation and angioplasty-capable,
which can be used independently of the airgun to accomplish
preparatory treatment before implantation discharge.
[3281] A positioning control and discharge control panel is mounted
on the airgun and described below under the section entitled Airgun
Control Panel. A barrel-assembly of sufficient angioplasty
capability for use while separated from the airgun as a
free-standing apparatus until engaged in the airgun to initiate
implantation discharge is provided with its own power and control
housing with side mounted control panel for these separate
functions. A universal power and control housing for fitting onto
any angioplasty-capable barrel-assembly to include
combination-forms must incorporate all the controls needed for any
barrel-assembly making it costly and usable with only one
barrel-assembly at a time.
[3282] The potential of thermal or cryogenic angioplasty, of a
tissue bonding agent, or of these in combination to repair a
propensity for separation between or within the layers or the
tunics within the wall of a ductus warrants study. No laser-based
apparatus similar to those used to reattach a retina appears
available. When the intima or internal layer is the source of the
stenosis, the apparatus and equipment described herein can be used
only if it can be reattached to the media. Then any stent used must
be endoluminal or conventional. To reduce costs, certain components
that would be incorporated into a fully capable barrel-assembly but
which are considered unnecessary for a specific procedure are
omitted.
[3283] Intermediate forms for use while engaged in the airgun allow
omission of an inmate power source (battery-pack), radial
projection units, and the inclusion of fewer controls on the
on-board control panel, but are limited to light and simple
impantation discharge-preparatory angioplasty or ablation. If
produced with connections at the rear rather than by means of a
side-socket as addressed below in the section entitled
Barrel-assembly Side-socket, these preclude attachment at the back
of the barrel-assembly of a vortex tube, CO.sub.2, or NO.sub.2
cartridge for thermal angioplasty.
[3284] Electrical connection through the airgun to the power supply
is either as shown in FIG. 72 with the proximal end-plate 99
engaged in the airgun chamber as shown in FIG. 74 so that multiple
electrical contact connector terminal 101 is brought into contact
or as shown in FIG. 75 by means of external extension cord 109. For
a minimal capability barrel-assembly dependent upon connection to
the airgun power supply for power, these connections include at the
least those for rotatory and thermal control of the turret-motor
and any other heat-windows and those to energize the miniball
recovery electromagnets in the nose of the muzzle-head. In
comparison, an ablation or ablation and angioplasty-capable
barrel-assembly incorporates an inmate power source within the
slidable power and control housing as not to depend upon the airgun
power supply.
[3285] It can, however, include a multiple electrical contact
connector terminal or electrical connection plate as does an
incapable embodiment, in which case it can be controlled from
either the control panel on the airgun or that on the power and
control housing. In more capable barrel-assemblies, to minimize
human error, the airgun control panel includes only controls for
the airgun, and the power and control housing control panel
includes only controls for mechanical and thermal ablation,
angioplasty, and the use of radial projection units. A
minimally-capable barrel-assembly that performs a preemptive
thermoplasty at the nose ahead of the discharging muzzle-ports or
exit-holes best uses a separately energized nose heat-window, the
recovery electromagnets required for tractive use during
discharge.
[3286] This heat-window, which still draws power from the airgun
power supply, is best controlled on the barrel-assembly, such as a
small control knob mounted to terminal plate 106 in FIG. 75. To
stent without an antecedent angioplasty or where it is suspected
that a previous angioplasty left rupturable plaque in place
requires the addition of minimal angioplasty means to minimize the
risk of releasing embolizing debris by contact with the
muzzle-head. Accordingly, any time that a barrel-assembly is
introduced into an atheromatous artery, especially one that has not
been angioplastied or that a preceding angioplasty notwithstanding,
is believed could retain rupturable plaque, thermal or cryogenic
angioplasty is performed.
[3287] The application of heat to the lumen wall is for precluding
to the extent possible, the rupture of plaque and not for altering
the mechanical properties of the lumen wall in preparation for
implantation, which requires only routine adjustments in ejection
force or exit velocity. The means for achieving good thermal
conductivity and focus are described below in the section entitled
Thermal Conduction Windows (Heat-windows) and Insulation of the
Muzzle-head Body in Thermal Ablation or Thermal Angioplasty-capable
Barrel-assemblies. A minimal angioplasty capability is attained by
making the windings already present in the implant spherule
recovery electromagnets heatable to achieve a minimal thermal
angioplasty capability.
[3288] While barrel-assemblies intended for use in both diseased
arteries and stenosed ductus of other types provide temperature
settings from 50 to 100 degrees centigrade in ten increments of
five degrees each, barrel-assemblies for use limited to
atheromatous arteries are set to 90 degrees centigrade. Such a
precautionary angioplasty would best be accomplished passively as
an ancillary or incidental function attendant upon, rather than as
a separate procedure preliminary to, implantation. However, a. The
recovery electromagnets toward the front of the muzzle-head cannot
be heated and used tractively at one and the same time, b. The use
of one recovery electromagnet to heat while the other is used to
recover would represent a circumferential insufficiency on both
scores, c. For both (1) Freedom of movement and (2) Access to the
free end for insertion of a cooling catheter, the barrel-assembly,
even when used for minimal thermal angioplasty- (lumen wall
priming-searing or cautery capability, is best completely
separately from and independently of the airgun.
[3289] Thus, even though such a precautionary angioplasty is not
discretionary as is an angioplasty that targets atheromatous
tissue, a minimal thermal angioplasty- (lumen wall priming searing-
or cautery-) capable barrel-assembly is still used independently of
an airgun and provided with an on-board hand-grip Barrel-assembly
hand-grip, as addressed below in the section entitled
Barrel-assembly Hand-grip, that contains a battery pack and mounts
a control panel, as addressed below in the section entitled
Ablation or Ablation and Angioplasty-capable Barrel-assembly
Onboard Control Panel. The minimal capability angioplasty
barrel-assembly is thus an abbreviated version of which the
capabilities fall within the scope of those included in an
angioplasty-capable barrel-assembly.
[3290] However, lacking a heatable turret-motor and radial
projection units and therefore the means for performing a proper
angioplasty, such an intermediate level barrel-assembly can be
produced at lower cost. In the simplest and least expensive
minimally capable barrel-assembly, which is not provided with
onboard controls for use independently of the airgun, a separately
powered nose-cap or nose-envelope heat-window at the front of the
muzzle-head where contact is first made with the lumen wall is
required; the turret-motor reserved for rotation of the muzzle-head
during discharge. Such a barrel-assembly is seldom if ever used
while removed from the airgun, when it still draws power from the
airgun power supply and does not use the turret-motor as a heating
element for thermoplasty.
[3291] Whether engaged in or removed from the airgun, the
turret-motor in a more capable barrel-assembly can alternate
between heating element for thermoplasty and to rotate the
muzzle-head, although an interval for cooling, readily shortened by
inserting a cooling catheter, is allowed. Rotation during use to
heat pertains only to a heat-window in the form of a slit or slot
such as 179 in FIG. 64 as unidirectional; a heat-window that
completely encircles the turret-motor is omnidirectional
(circumferential), negating the need for rotation. With the
barrel-assembly disengaged from the airgun, rotation of a slit type
heat-window while heating can usually be accomplished by hand. If
not, then rotation of a directional heating source is accomplished
with a radial projection heater tool-insert or a multiplicity
thereof in any formation which uses the turret-motor for
rotation.
[3292] The turret-motor is controlled with the airgun control panel
during discharge and the barrel-assembly power and control housing
during ablation or angioplasty when the barrel-assembly is
disengaged from the airgun. Once an angioplasty-capable
barrel-assembly is inserted into the airgun, the electrical
connection used to energize the electromagnets and turret-motor are
used almost exclusively in support of discharge rather than as
heating elements, controls for ablation or angioplasty on the
barrel-assembly power and control housing when the barrel-assembly
is usually disengaged from the airgun, although angioplasty and the
injection of medication, for example, may occasionally be
interjected during the discharge phase. With such a barrel-assembly
inserted in the airgun, discharge-related electrical connections
are generally made automatically by engagement of the
barrel-assembly in the airgun chamber as shown in FIGS. 72 and
74.
[3293] This does away with the tethering represented by cord 109 in
FIG. 75 that is unobjectionable in a minimally-capable
barrel-assembly for which, unlike the capable type, use when
removed from the airgun is exceptional. An ablation or ablation and
angioplasty-capable barrel-assembly may be tethered when a
commercial cabled device with its own controls and power source,
such as a linear atherectomy cutter is used; however, it is
preferred that such devices be specially adapted for nonthethering
attachment if not building into the power and control housing. In
more capable ablation and atherectomy-capable barrel-assemblies, a
side-socket can admit cabled devices and fluid lines.
[3294] VII2g(2). Minimally Ablation or Ablation and
Angioplasty-Capable Barrel-Assembly Side-Socket
[3295] Side-sockets are addressed below in the section entitled
Ablation or ablation and angioplasty-capable Barrel-assembly
Side-socket. Unlike an ablation or ablation and angioplasty-capable
barrel-assembly, a minimally capable barrel-assembly is not devised
for use as an independent apparatus and therefore has no power and
control housing and hand grip that includes a side-socket.
Electrical radial projection units in the muzzle-head are connected
to the airgun power supply on engagement in the airgun chamber.
When present, an electrical side-socket is mounted directly to the
barrel-catheter in a small box or enclosure that can be slid along
the barrel-catheter along sliding or brush contact strips.
[3296] The connectors consist of miniature or microminiature jacks
or receptacles on a side of the box. Side-sockets not automatically
closed by a one-way swing-away cover also serve as gas pressure
relief outlets. Unlike the connection of the components within the
barrel-assembly through the end-plate, the incorporation of a
side-socket allows the continued connection and use of ablation,
angioplasty, or intermittent (touch-up) intima stabilizing
components and functions when the barrel-assembly is engaged in the
airgun chamber. Such include side-sweeper type abrading radial
projection unit tool-inserts with trap-filter, a `cold` air gun for
delivering cold or hot air, attached cylinders of compressed or
liquified gas for chilling, and when installed in an edge-discharge
barrel-assembly, a laser. Any fluid connection requires a fluid
side-socket that provides a passageway for the pipe from the
external source to enter the central canal.
[3297] The box, which is mounted as would a power and control
housing, includes a levered cam engagement detent so that it can be
slid along the barrel-catheter and temporarily fixed in position.
The range in longitudinal position available is not limited to that
of brush contact with the strips; however, electrical control is
lost when the ends of the sliding contacts are overextended.
Exceptionally, a minimally capable barrel-assembly can include a
fluid operated radial projection circuit. Coupling of the incoming
line to the circuit is then limited to a single position along the
length of the barrel-catheter at which the openings on the inner
surface of the housing and inlet to the circuit align, this
position indicated by a circumferential tic alignment mark at that
position.
[3298] The addition of an electrical side-socket allows a minimally
ablation or ablation and angioplasty-capable barrel-assembly draw
power while not engaged in the airgun. Tethered thus, freedom of
movement is not equal to that of an ablation or ablation and
angioplasty-capable barrel-assembly. Further supplementation such
as an attachable battery pack with controls and control panel to
operate the components within the barrel-assembly, or an open
central canal as provided in a combination-form type ablation or
ablation and angioplasty-capable barrel-assembly is considered as
inferior approximation to an ablation or ablation and
angioplasty-capable barrel-assembly produced as such.
[3299] VII2g(3). Minimally and Fully (Airgun-Independent) Ablation
or Ablation and Angioplasty-Capable Radial Discharge
Muzzle-Heads
[3300] Muzzle-heads for use in blood vessels differ from those
limited to use for ablation in requiring gas return channels to
prevent the introduction of gas into the bloodstream. All but
limited purpose embodiments incorporate a heating element or
excimer laser at the nose for ablation or angioplasty, those small
in gauge a heating element as this does not require a cable
entirely through the axis as in a combination-form barrel-assembly
with edge-discharge muzzle-head of the kind shown in FIG. 66.
[3301] VII2g(3)(a). Rapid Cooling Catheter and Cooling Capillary
Catheter for Cooling Heated Turret-Motor, Electrically Operated
Radial Projection Unit-Lifting Thermal Expansion Wire and Heaters,
and Recovery Magnets
[3302] To quickly return the thermal angioplasty turret-motor, one
or both brush-lifting thermal expansion wires, and one or both
recovery electromagnets of the recovery and extraction miniball
electromagnet assembly to body temperature, a cooling catheter, as
addressed below in the section entitled Cooling Catheters
(Temperature-changing Service-catheters), is passed down the
barrel-assembly so that its cold air is delivered in adjacent
relation to these components. Because in a combination-form
barrel-assembly, the longitudinal center is taken up by an
atherectomy burr or excimer laser cable, an edge-discharge
muzzle-head must be used, so that only a spare barrel-tube is
available for passing the rapid cooling capillary catheter up to
the turret-motor.
[3303] Fluid circuits can deliver a fluid prechilled or preheated
to a target temperature, but electricalcircuits cannot. A fluid
circuit can be used to achieve and transmit heat, a thermoplasty
temperature for example, more quickly than can an electrical
circuit, but chilling, that is, reversion to body temperature or
attaining cryoplasty temperature (-10 degrees centigrade) is not
currently practicable using electrical means. Such means thus
necessitate the pre- or midprocedural intromission in a barrel-tube
or the central canal of a chilled rod, or cooling catheter. Cooling
catheters can seal in a solution such as one part propanol to three
parts water and thus remain pliable or can circulate a refrigerated
coolant from a remote pump.
[3304] Since cooling catheters can also be preheated, designation
as `cooling` is nominal and based upon primary use to quickly cool
an electrically heated component. The emergent field of electronic
refrigeration may eventually supplant the need for cooling
catheters, and the related field of electronic thermometry
application to the control of winding temperatures to minimize
thromogeneric temperatures during thermoplasty, that is, achieve 90
degrees centigrade quickly, hold that temperature during the
thermoplasty, then revert to normal body temperature as soon as the
thermoplasty is completed. Once made practicable, electronic
refrigeration will have application to cooling catheters and
electrically operated radial projection tool-insert cold plates for
performing a cryoplasty, for example.
[3305] Currently pursued along various lines, electronic
refrigeration has the potential to allow changes in temperature at
a remote point, eliminating the need to pipe a heated liquid or gas
to achieve thermoplasty or chilled liquid or gas to achieve
cryoplasty temperature with a barrel-assembly (see, for example,
Majumdar, A. 2009. "Thermoelectric Devices: Helping Chips to Keep
their Cool," Nature Nanotechnology 4(4):214-215; Chowdhury, I.,
Prasher, R., Lofgreen, K., Chrysler, G., Narasimhan, S., Mahajan,
R., Koester, D., Alley, R., and Venkatasubramanian, R. 2009.
"On-chip Cooling by Superlattice-based Thin-film Thermoelectrics,"
Nature Nanotechnology 4(4):235-238; Petta, J. R. 2009. "Electronic
Refrigeration on the Micron Scale" Physics 2,27; Prance, J. R.,
Smith, C. G., Griffiths, J. P., Chorley, S. J., Anderson, D.,
Jones, G. A. C., Farrer, I., and Ritchie, D. A. 2009. "Electronic
Refrigeration of a Two-Dimensional Electron Gas," Physical Review
Letters 102(14): 6602-6606; and Giazotto, F., Heikkla, T. T.,
Luukanen, A., Savin, A. M., and Pekola, J. P. 2006. Opportunities
for Mesoscopics in Thermometry and Refrigeration: Physics and
Applications," Reviews of Modern Physics, 78(1): 217-274, updated
preprint to 2008 under title revised as "Thermal Properties in
Mesoscopics: Physics and Applications from Thermometry to
Refrigeration," available at
http://arxiv.org/PS_cache/cond-mat/pdf/0508/0508093v4.pdf; Edwards,
H. L, Niu, Q., and de Lozanne, A. L. 1993. "A Quantum Dot
Refrigerator," Applied Physics Letters 63(13): 1815-1817).
[3306] Related technology should make possible small-scale
thermometry that can be incorporated into the onboard controls of
ablation or ablation and angioplasty-capable barrel-assemblies for
temperature control. A noncombination-form barrel-assembly with
center-discharge muzzle-head, however, provides a central canal to
allow a cooling catheter of larger diameter and an ejection-head
channel for insertion of the distal end of the cooling catheter for
more direct access to the recovery electromagnets. The gas return
paths prevent cooling gas from entering the bloodstream. The
mechanism by which the radial projection units are controlled is
described under the sections below entitled Structure of
Electrically Operated Radial Projection Units and Radial Projection
Unit Control and Control Panels, Elecrical and Fluidic or
Piped.
[3307] A cooling catheter is needed when the internal configuration
of the muzzle-head fails to obstruct the release of pressurized gas
into the bloodstream. Using a center-discharge muzzle-head, when
the turret-motor is sent heating current to quickly raise to and
hold the temperature at 90 degrees centigrade for thermal
angioplasty, preferably the slit valve but possibly a spare
barrel-tube is used to admit the rapid cooling extruded
polytetrafluoroethylene capillary catheter. With such a
muzzle-head, when one or both miniball recovery tractive
electromagnets are used for thermal angioplasty, the rapid cooling
capillary catheter is advanced up through the cental canal and into
the ejection head rapid cooling capillary catheter insertion
channel.
[3308] In a combination-form angioplasty barrel-assembly, the slit
valve is eccentric. Because the electromagnets are contained within
chambers that directly communicate with the bloodstream beyond the
gas return paths, blowning cold air directly on the electromagnets
would risk introducing gas into the bloodstream. For this reason,
the end of the capillary catheter is closed and side-holes are
used. Cooling of the electromagnets is through the metal of the
ejection head, the larger diameter of the insertion channel
allowing the cooling gas to circulate against the interior walls of
the insertion channel and exit through the central canal.
[3309] Using an edge-discharge muzzle-head as affords a central
passageway for interchanging different cabled devices in a
combination-form barrel-assembly or incorporating a fiberoptic
endoscope, for example, the cooling catheter is moved forward until
its distal tip closes off the muzzle-port of the barrel-tube
through which the cooling catheter was passed. If only one
electromagnet had been used to perform a thermal angioplasty,then
the cooling catheter is passed through a barrel-tube proximal to
that electromagnet, which can be identified, each barrel-tube
marked on end-plate 99 in FIG. 72. The asymmetry of this position
and separation by metal surrounding the electromagnets mean that
the rate volume of chilled air delivery must be greater than in a
center-discharge muzzle-head.
[3310] The use of more than one cooling catheter in an
edge-discharge muzzle-head to ameliorate the less effective cooling
associated with the asymmetry of cooling catheter placement is
practicable when the caliber of the barrel-tube or barrel-tubes
used for discharge are not affected. Combination-form
barrel-assemblies with edge-discharge muzzle-heads can be
deliberately designed to be cooled in this way. The functionality
of providing a service-channel for access to the muzzle-head for
various purposes is discussed above. Referring now to the detailed
view of a center-discharge muzzle-head shown in FIG. 67 with laser
169 occupying central channel 155, and in FIG. 66 with central
channel 155 unoccupied, for ease of insertion and passing down
central channel 155 to ejection head 84 and recovery electromagnets
65 of a cooling catheter (rapid cooling catheter, rapid cooling
capillary catheter), the distal end of cooling catheter 180 in FIG.
68 can be closed off and angled (chamfered, conical).
[3311] When cooling catheter 180 consists not of a prerefrigerated
solid rod but instead releases a chilled fluid, cooling catheter
180 includes round side-holes 181 that surround and extend
proximally over the length to be cooled. When radial projection
units proximal to the muzzle-head need not also be cooled, this
length will be that of the muzzle-head, thus including the
turret-motor with through-bore torque turret-motor rotor 82 and
stator 62 and recovery electromagnet 65 assembly.
[3312] Chilled air is delivered through the cooling catheter by
connecting its free proximal end with a diameter-reducing adapter
to the nozzle of a cold air gun using a vortex tube supplied with
compressed air, such as manufactured by the Vortec Division,
Illinois Tool Works Air Management; Airtx International; Exair; and
Pelmar Engineering. The base of the cold air gun is fastened to the
side of the interventional airgun cabinet. Alternatively, high
purity 1,1,1,2-tetrafluoroethane (R134a) cryogen spray is blown
through the cooling catheter side-holes under low pressure by
inserting the free proximal end of the cooling catheter into the
spray nozzle hole of the aerosol can containing the
tetrafluoroethane, the need for a diameter-changing adapter
depending upon the diameter of the cooling catheter.
[3313] Testing has revealed tetrafluoroethane to be safe (Emmen, H.
H., Hoogendijk, E. M., Klopping-Ketelaars, W. A., Muijser, H.,
Duistermaat, E., Ravensberg, J. C., Alexander, D. J., Borkhataria,
D., Rusch, G. M., and Schmit, B. 2000. "Human Safety and
Pharmacokinetics of the CFC Alternative Propellants HFC 134a
(1,1,1,2-tetrafluoroethane) and HFC 227
(1,1,1,2,3,3,3-heptafluoropropane) Following Whole-body Exposure,"
Regulatory Toxicology and Pharmacology 32(1):22-35; Gunnare, S.,
Ernstgaard, L., Sjogren, B., and Johanson, G. 2006. "Toxicokinetics
of 1,1,1,2-tetrafluoroethane (HFC-134a) in Male Volunteers After
Experimental Exposure," Toxicolology Letters 167(1):54-65).
[3314] To allow the rigidity necessary for very thin, for example,
0.39 millimeter, cooling catheters to be passed to the muzzle-head
through an available barrel-tube, the cooling catheter is made of
polytetrafluoroethylene. In a combination-form barrel-assembly that
must have an edge-discharge muzzle-head the use of an available
barrel-tube for this purpose is unavoidable. Although the effect is
slight because of the small diameter of the cooling catheter, this
affects the flexibility, hence, trackability of the
barrel-catheter. Since inserting the cooling catheter can assist in
advancing the barrel-assembly, so long as care is taken to avoid
stretching injury, this can be used to advantage.
[3315] Tubes and solid rods made of many different materials and
covering a wide range of flexibility can likewise be inserted to
stiffen or straighten the distal end of the barrel-assembly. At
relatively close distances, a powerful hand-held electromagnet,
even if portative rather than tractive, can also be used to aid in
steering the muzzle-head, the more so if the muzzle-head
incorporates magnetically susceptible matter for this purpose.
Connecting the B.sub.0 magnet of a magnetic resonance imager as
addressed below in the section entitled Use of an External
Electromagnet to Assist in Mishap Recovery and Stereotactic Arrest
and Extraction of a Circulating, Dangerously Mispositioned, or
Embolizing Miniball allows not only muzzle-head steerability but
also atheromatous lesions to be compressed much as does a
balloon.
[3316] A dividing and diameter changing adaptor allows the use of
multiple cooling catheters with a single cold air gun; the use of a
separate cold air gun for each cooling catheter is generally not
necessary. Provided trackability is not impaired, to eliminate
insertion time and allow immediate retreat from the 90 degree
centigrade target temperature for thermal angioplasty back down to
body temperature, multiple cooling catheters are prepositioned.
Otherwise as many cooling catheters are prepositioned as do not
affect trackability. Using a center-discharge barrel-assembly, the
main and larger diameter cooling catheter is passed down the
central canal and into the ejection head channel with another,
usually capillary gauge, cooling catheter passed down the
barrel-tube closest to the heated element.
[3317] VII2g(3)(b). Turret-Motor and Recovery Electromagnet
Insulation, Leads, and Control of Winding Temperatures when Used as
Heating Elements in Ablation or Ablation and Angioplasty-Capable
Barrel-Assemblies
[3318] The thermoplasty resources in an ablation or ablation and
angioplasty-capable barrel-assembly include the turret-motor and
recovery electromagnet windings and any electrical and/or fluidic
radial projection units. Those in a radial projection catheter
include only electrical and/or fluidic radial projection units.
Electrical heating elements, hence, electrical radial projection
systems, allow only heating, not cooling; rapid cooling from the
thermoplasty temperature, usually 90 degrees centrigrade, back down
to body temperature must be accomplished with chilled fluid. To
rise from body temperature past thrombogenic temperatures to the
procedural temperature as quickly as possible with an electrical
heating element requires initially surging, continuously
modulating, and sustaining the current so long as the target
temperature is needed.
[3319] Turret-motors and tractive electromagnets to serve as a
heating elements for thermal angioplasty must incorporate special
features of thermal and electrical insulation, to include winding
insulation that is effective as an electrical but not as a thermal
insulator, such as Master Bond EP34AN epoxy adhesive/sealant
(thermal conductivity 22-24 BTU/in/ft.sup.2/hr/.degree. F.),
pyrolytic boron nitride, or boron nitride, for example. Efficient
radiation to the endothelium of winding-generated heat is through
heat-windows, addressed in the section to follow. Since
atheromatous lesions are usually asymmetrical, restricting the
radiation of heat from the muzzle-head allows less heat to be
directed toward less affected radii, hence, more discretionary
treatment.
[3320] This is approximated by providing that only a delimited
arcuate sector of the proximal portion of the muzzle-head shell or
body serving as motor housing will radiate heat, the balance of the
housing being thermally insulating. The turret-motor as thermal
angioplasty heating element can be supplemented through use of the
tractive electromagnet(s) for the same purpose. Ideally, once the
heat within the muzzle-head body met or exceeded 90 degrees
centigrade, the heat transmission window would radiate only 90
degrees centigrade. The sparsely intermittent duty of the
turret-motor in positional control and the fact that the motor is
fed current only when needed mean that little heat is
generated.
[3321] This allows a sector of the muzzle-head shell to
exceptionally be made of a material without value as a thermal
insulator. Since atheromatous lesions are usually asymmetrical, the
capability to differentially heat the turret motor over a
restricted arc of its circumference gives more discretionary
control, but also requires that lower thrombogenic temperatures are
not transmitted to the adjacent arcs, as discussed below. Silver
and copper having been specified as the materials preferred for the
heat-windows on the basis of maximum thermal conductivity, the
selection and thickness of the materials used in heat-windows does
not take into account such alteration in thermal conductivity as
results from the fact that the exterior surface of the heat-window
will be wetted with blood or some other bodily fluid.
[3322] The ideal turret-motor as heating element would quickly rise
from room temperature to 90 degrees centigrade, quickly drop from
90 degrees to room temperature, and be enclosed within a motor
housing having a copper window slot through which the heat would be
conducted, other portions of the entire turret-motor housing
surface made of a material such as polytetrafluoroethylene or
stainless steel having a markedly greater heat transfer coefficient
or thermal condctivity the motor tolerating the heat otherwise
retained without significant radiation to the surrounding lumen.
Angioplasty performed manually before intiating stenting by
inserting the proximal end of the barrel-assembly into the airgun,
the motor would not, however, be used to rotate the muzzle-head
during use as a heater.
[3323] For use as a heating element for the thermal angioplasty of
a delimited arc of the lumen wall, a substantially temperature
isolated arc of the turret-motor must be quickly heatable from a
cool condition to 90 degrees Centigrade, necessitating wire and
winding insulation that resists melting failure in small gauges
depending upon size, especially when platelet blocking or
anticoagulant medication is contraindicated making the avoidance of
thrombogenic temperatures intermediate between zero and 90 to be
avoided. To keep the nonangioplastic operating temperature of the
turret-motor well when used for positional control below
thrombogenic levels, the control circuit delivers current to the
motor only when the motor is used.
[3324] To avoid the intevening thromogenic temperatures, the
subminiature silver wire turret-motor and recovery tractive
electromagnet windings must be capable of being quickly elevated to
90 degrees centrigrade, the initiating of heating commencing with a
current surge that gradually levels off to maintain a constant
temperature as mentioned in the preceding sections entitled Concept
of the Extraluminal Stent and the Means for Its Placement and
Thermal Conduction Windows (Heat-windows) and Insulation of the
Muzzle-head Body in Thermal Ablation or Thermal Angioplasty-capable
Barrel-assemblies. Overheating normally results from excessive
starting torque or torque at elevated speeds, whereas here heat is
deliberately applied when the motor is not in use as a driver. That
heat must, however, be dealt with when the motor is used as a
driver.
[3325] Since fluoropolymers are effective thermal insulators, when
the muzzle-head is or coated with a thin layer of a fluoropolymer
to obtain a no-stick surface, the turret-motor is given a thinner
or no such coating. However, if the coating has microscopic gaps, a
thinner coating over the motor may still allow sufficient heat to
pass through to the lumen wall. Even though rotation is
intermittent or discontinuous and angle-to-angle within a circle or
semicircle, use as a rotary driver immediately following use as a
thermal angioplasty heater is better accomplished with a
turret-motor that dissipates the excessive heat previously required
quickly and thus averts rotatory instability (see, for example,
Basu, A., Moosavian, S. A., and Morandini, R. 2005. "Mechanical
Optimization of Servo Motor," Journal of Mechanical Design
127(1):58-61).
[3326] Heating the stator to perform thermal angioplasty represents
a separate mode of turret-motor operation and is not employed when
it is necessary to rotate the muzzle-head. For example, to combine
thermal and side-sweeping angioplasty, the action is carried out
transluminally under manual control with one or both of the
side-brushes--which may be the same or different in bristle
stiffness and tip conformation--deployed at a fixed rotational
angle with the turret-motor heated at stall. Then to rotate the
side-brush or brushes, the manual action is suspended, the
turret-motor switched for rotation, the brush or brushes rotated,
and the turret-motor switched back to heat while stalled in order
to resume thermal angioplasty at the new brush rotational
angle.
[3327] The insulation of the turret-motor must tolerate sufficient
current for thermal angioplasty without melting, and the
turret-motor must be well temperature insulated from the more
forward elements of the muzzle-head or extremes of temperature will
produce a temperature gradient that will result in thrombogenic
temperatures in these more forward elements at and around 50
degrees centrigrade (122 degrees Fahrenheit) (Post et al. 1996).
For thermal angioplasty, the turret-motor stator must quickly pass
the thrombogenic range and reach a temperature of 90 degrees
centigrade when sent higher current while stalled, and must just as
quickly cool to room temperature when the current is removed.
[3328] In a fully ablation or ablation and angioplasty-capable
barrel-assembly, when current is sent to the turret-motor and/or
either recovery electromagnet winding for use as a heating element,
an interval or lag-time precedes the attainment and stabilization
of the target temperature at the heat-window. The same pertains to
electrical tool-insert heating elements, addressed in the section
below entitled Temperature Control in Electrical Tool-inserts.
Where fluid or piped heat-windows passed through insulated lines
can deliver fluid already heated or chilled at the target
temperature to effect rapid cooling, electrical heaters, unless
just removed to stabilize medication in preloaded syringe
tool-inserts, commence heating at between room and body
temperature.
[3329] The more quickly can the thrombogenic temperatures
separating the body and target or operative temperature be passed
through and the target temperature stabilized, the less platelet
blockade will be needed, and the less will be the risk of bleeding.
Large barrel-assemblies for use in the trachea or bronchi and
gastrointestinal tract, for example, can accommodate microminiature
thermocouples to sense the temperature as such, allowing
independent proportional-integral-derivative closed-loop control of
the temperature at each heat-window.
[3330] A precision thermocouple consisting of a fine bimetallic
thermal expansion strip, such as one made of invar steel and brass
or aluminum, that thermomechanically completes the circuit for
current flow-through by making contact-connection only when its
temperature corresponds to over 50 degrees centigrade (122 degrees
Fahrenheit) for thermal ablation (see, for example, Habash, R. W.,
Bansal, R., Krewski, D., and Alhafid, H. T. 2006. "Thermal Therapy,
Part 1: An Introduction to Thermal Therapy," Critical Reviews in
Biomedical Engineering 34(6):459-489; Diederich, C J. 2005.
"Thermal Ablation and High-temperature Thermal Therapy: Overview of
Technology and Clinical Implementation," International Journal of
Hyperthermia 21(8):745-753) and 90 degrees centrigrade (194 degrees
Fahrenheit) for angioplasty at the heat-window-endothelial
interface, can be used.
[3331] If external to the barrel-assembly, which is more likely
with large gauge barrel-assemblies supported by commercial
closed-loop temperature controllers, the controller is connected
through an electrical side-socket. The temperature for other
applications of heat addressed herein vary according to use for
thermal hemostasis (thermocoagulation -70 degrees centigrade (see,
for example, Conway, J. D., Adler, D. G., Diehl, D. L., Farraye, F.
A., and 7 others 2009. "Endoscopic Hemostatic Devices,"
Gastrointestinal Endoscopy 69(6):987-996), the specific adhesive
heated to accelerate initial setting, or medication heated
following electrical or fluidic radial projection unit syringe
injection to accelerate a chemical reaction or uptake, for
example.
[3332] As addressed below in the sections entitled Electrical
Tool-inserts, to Include Gas Discharged Injection and Ejection
Syringes and Fluidic Tool-inserts, to Include
Ejector-irrigator-aspirators and Injectors, both electrical and
fluidic radial projection unit syringe tool-inserts can warm, and
fluidic syringes can chill medication prior to release within the
lumen (ejection), or hypoendothelialor hypointimal injection. With
independently heatable recovery electromagnets, three heat control
circuits or channels are required in the hand-grip in addition to
the prefereably separate drive-control circuitry for the 3-phase
turret-motor.
[3333] With either temperature (true closed-loop) or current (quasi
closed open-loop or open-loop even with respect to current)
control, each winding can be assigned its own embedded
microcontroller, or one microcontroller can independently or
jointly control the temperature outside each heat-window. While a
larger microcontroller could be programmed to control the
turret-motor and recovery electromagnet windings both for heating
and electroactuation, the separate control of each magnet and the
motor is preferred as affording the greater dependability of
redundancy. Barrel-assemblies for use in small gauge lumina do not
allocate space for a temperature sensor at the expense of working
elements.
[3334] Instead, quick rise to and stabilization at the target
temperature is accomplished indirectly and remotely, preferably
through closed-loop regulation of the current or current feedback
control, by a power and control housing, or battery-pack hand-grip,
embedded microcontroller. Control can, however, be genuinely
open-loop, meaning without current feedback. That is, a separate
microcontroller for each of the three windings or one larger
microcontroller is programmed to control the current by equivalence
to temperature. The control of the current to each winding is thus
close-loop, but control of the equivalent temperature is
open-loop.
[3335] Rather than using feedback from a temperature sensor, the
microcontrollers adjust the current to each each winding from the
inmate battery-pack, the airgun power supply, or remote power
supply through a digital potentiometer. Space for thermal
insulation limited, protracted heating will eventually be conducted
through the muzzle-head and must be reversed. Whether control is by
temperature in a large or current feedback in a small
barrel-assembly, to rise from body temperature outside each
heat-window past thrombogenic temperatures to the target
temperature as quickly as possible requires initially surging, then
modulating the current to hold the temperature constant until shut
off when the temperature must be brought back down to body
temperature as quickly as possible.
[3336] With electrical heating, a cooling catheter or nearby
fluidic radial projection fluid line must be used to quickly return
a heated winding back down to body temperature. A negative feedback
control microcircuit contained within the hand-grip shaped battery
pack is used to surge the current when heating is begun and then
gradually drop off the current with time, thus maintaining the
temperature substantially constant until the cooling catheter is
used to cool down the muzzle-head. The longer heating is continued,
the more can heat accumulate within and be conducted through the
muzzle-head.
[3337] Current feedback control in electrically operated radial
projection tool-inserts, addressed below in the section entitled
Electrical Tool-inserts, to Include Gas discharged Injection and
Ejection Syringes, not only preserves the space that a temperature
sensor would require but allows the control of all other electrical
tool-insert functions, all current controllable. Redundancy for
dependability equally important with electrically operated radial
projection tool-inserts, these likewise are preferably controlled
by separate microcontrollers. Incorporating different materials in
different dimensions, each type muzzle-head will exhibit different
temperature characteristics. The current requirements to quickly
move between body and thermoplasty temperatures using each type
embodiment will therefore be unique.
[3338] The control of temperature must therefore be determined on
the basis of empirically testing each type if not each muzzle-head
for current-to-temperature equivalency, the relation of temperature
to current predetermined using the exact combination of components
to be controlled. A specification sheet that states the times and
temperatures for using heat and cooling catheters must be supplied
with the specific barrel-assembly. The cooling catheter used for
this can enclose a coolant and be refrigerated or provide a
biluminal circuit for flowing a coolant, usually cool water. A
side-socket allows the use of a remote commercial coolant pump and
controls.
[3339] For free manipulability, however, ablation or ablation and
angioplasty-capable barrel-assemblies whether large or small are
preferably untethered by wires or hoses, control components such as
temperature microcontrollers incorporated into the power and
control housing, or hand-grip shaped battery-pack. Most often, the
application of heat during a thermal angioplasty or to accelerate
the initial setting time of a surgical cement, for example, cannot
be kept so brief or intermittent that an objectional buildup of
heat can be avoided. Especially in an angioplasty barrel-assembly
for use to remove plaque so extensive that to treat it requires
inordinate heat on-time, a cooling catheter is used to
intermittently cool the muzzle-head.
[3340] Generally the turret-motor windings are not isolated for
heat control; when used as a heating element, the turret-motor
stator is energized as a unit despite having more than one winding
with resistances between these. A heat-window can completely
surround the turret-motor, or the radiation of heat can be
constrained to circumscribed heat-windows which then aim the heat.
Only muzzle-heads that are too small (other than for the low
conductivity polymer shell) to insulate and thermally isotropic
warrant limitating current to one motor winding.
[3341] VII2g(3)(c). Thermal Conduction Windows (Heat-Windows) and
Insulation of the Muzzle-Head Body in Minimally or Fully Thermal
Ablation and Thermal Ablation and Angioplasty Capable
(Independently Usable) Barrel-Assemblies
[3342] Thermal or "heat" windows, such as those shown in FIGS. 64
and 70 are heat radiating sectors in the muzzle-head body or shell.
Heat-windows can be slit, slot, or all-around in form, the latter
kept distal to the muzzle-ports or exit-holes. Peltier devices
mounted to allow rotation can be used to furnish either heat or
chilling. While not shown in FIG. 64, a heat-window is usually also
present at the nose as seen in FIG. 70. A nose heat-window is given
a toroidal cross-section to accommodate the distal tip of a
nose-centered cabled device, such as a fiberoptic endoscope, for
example, or the nose opening in a combination-form
barrel-assembly.
[3343] While the thinness of the thermal insulation required in the
body or shell of the muzzle-head makes thermal isolation difficult,
the differential thermal conductivity of the window or windows in
relation to the speed with which the control electronics and
materials employed allow the target temperature to be attained and
receded from affords a level of thermal isolation sufficient for
thermal angiolasty with minimal risk of thrombogenicity due to heat
retentive temperature gradients surrounding the radiative window or
windows. For treating eccentric lesions, the heat-window or windows
overlying a turret-motor can be reduced structurally or with tape
to slits, slots, or rectangularly configured, rather than
circumferential.
[3344] The term heat-window also applies to electrical and fluid
tool-inserts, the latter even when used to conduct cold. Whereas
electrical heat-window tool-inserts are limited to heating,
generated by a coil, blank tool-inserts in piped radial projection
units can be used as hot or cold plates. By exchanging the
projection catheter or a tool-insert in the same projection
catheter, electrical and fluid tool-inserts can be replaced with
alternative tool-inserts that perform cutting (shaving), brushing,
injection, infusion, or aspiration functions. A heat-window at the
distal end of the muzzle-head is a blunt dome-shaped nose
heat-window. Heat-windows are of two types--those heated by passing
current through an actuator winding positioned just behind them,
and piped radial projection units, addressed below in the section
entitled Piped Radial Projection Units, which are heated or chilled
by flowing a heated or chilled fluid against the inner side of a
peripheral face-plate.
[3345] To afford a return path, the hot or cold gas, liquid, or gel
used to heat or chill a piped face-plate type heat-window must be
channeled through a dual lumen pipe or service-catheter passed down
the pipe to the face-plate. This section relates to the operation
of the heat-window or windows of the muzzle-head as can be
separately placed about or made to surround the turret-motor and
two recovery electromagnets in alternative use as heating elements
rather than as motion control devices. Such use must be
discretionary in that each of the three are usable at any time for
either moving or heating as required. When connected to a source of
hot gas, piped blank or flat-faced radial projection unit
tool-inserts made of thermally conductive material looking outward
toward the lumen wall and thermally insulated behind and to the
sides (within the elevation shaft) can be used as heat-windows.
[3346] These are situated in front of (distal to) the turret-motor
housing and to the rear of (proximal to) the muzzle-head flex
joint, and not superjacent to the turret-motor and recovery
electromagnet windings. The use of these together with winding
heated heat-windows is possible. While actuator winding-heated
heat-windows are limited to the conduction of heat, fluid (fluidic,
piped) radial projection unit blank tool-inserts can be heated or
chilled by delivering liquid or gas at the desired temperature to
their rear face and are interchangeable with numerous alternative
tool-inserts that allow the delivery of any fluid to the surface or
subsurface of the lumen wall.
[3347] Thermal windows allow the use of fluidic or piped radial
projection units to perform other functions. For the purpose of
allowing the muzzle-head to be used for performing a thermal
angioplasty, heat transfer from the windings within the muzzle-head
is by conduction, the small internal diameter of the different
systemic vasa to require treatment imposing stringent limitations
upon winding diameters and the thickness of the insulation that can
be used. The recovery electromagnets, turret-motor stator
(armature), and subminiature trap-filter deployment solenoid
windings all consisting of fine silver wire, ninety degrees
centrigrade is not so hot as to necessitate extraordinary
insulation of the windings, connections, or cabling.
[3348] Even though these components are positionally disabled
during thermal use, heat-conducting windows of silver, which has a
heat transfer coefficient at 25 degrees centrigrade of 429, or of
copper, 401, in the otherwise thermally insulated muzzle-head body
allows heat to be directed from the nose-cap (nose dome)
heat-window to the surrounding lumen wall and from the turret-motor
toward lesions that may be circumferentially asymmetrical or
eccentric. The higher temperature of a heat-window allows its
position to be viewed through thermal imaging, and, if redundantly,
allows the deliberate heating of a certain winding to assist in
pinpointing not only the location of the muzzle-head but the
orientation of the window.
[3349] To allow blood to flow past a muzzle-head flush fit to the
lumen, the turret motor must be smaller in diameter than the
portions of the muzzle-head that lie to the fore. Contact with the
wall of the lumen requires that the turret-motor heat-window
slightly protrude with smooth edges beyond the rest of the
circumference of the turret-motor. Some blood can then flow around
the heat-window past the motor body into the blood-grooves to the
fore. The nose-cap heat-window of the recovery electromagnets is
flush-mounted to the muzzle-body. The turret-motor and tractive
electromagnets represent three independently controllable heating
elements, each in its own circuit, in relation to which the
muzzle-head body can incorporate heat-radiating windows of any
shape, extent, separation, or connection.
[3350] However, except for ablation or angioplasty-incapable
barrel-assemblies, to avert the disruption of vulnerable plaque by
contact with the muzzle-head, all muzzle-heads for use in the
vascular tree have a heat-window in the form of a forward end
encompassing nose-cap and directional or circumscribed turret-motor
heat-window. While the heat-windows shown in FIG. 64 are
slot-shaped and thus directional, most turret-motor heat-windows
will collar about the muzzle-head entirely over the motor. The
recovery electromagnet heat-window or windows will more often be
slot-confured for directional use. Using the recovery
electromagnets separately, band, strip, or slit-shaped windows
along either segment of the muzzle-head body along one side behind
(proximal to) the nosecap heat-windo, for example, can be heated by
the motor proximally and/or the magnets distally.
[3351] Since in a combination-form barrel-assembly, the central
canal is occupied by an atherectomy burr or laser cable, this space
is unavailable, necessitating the use of an edge-discharge
muzzle-head, which requires that a spare barrel-tube be used as a
cooling catheter entry and service-channel The need to appropriate
a barrel-tube affects the maximum diameter of the barrel-tubes,
hence, the caliber of the miniballs that may be used when all the
barrel-tubes are to be used for the discharge of miniballs;
however, the diameter of the miniballs to be implanted will seldom
be forced smaller by this factor, and then only when a multiple
discharge barrel-assembly is preferred.
[3352] When the central canal in a multiple-discharge
barrel-assembly, such as a four-way radial edge-discharge
barrel-assembly, is already occupied by a laser or burr cable or by
a trap-filter, access to the central canal for use as a
service-channel to insert a cooling catheter of larger diameter is
preempted. This necessitates the use of a spare barrel-tube as
service-channel, limiting the cooling catheter to capillary tube
gauge, typically 0.38 millimeters in outer diameter. Even though
made of polytetrafluoroethylene for rigidity, to feed this fine
catheter down to the ejection head and confirm its correct position
represents a distraction and interruption that is avoided by
prepostioning the catheter. Whether used for cooling or the
delivery of medication or a lubricant, catheters requiring access
through a service-channel are prepositioned.
[3353] Solid rods of graduated stiffness preferred for the purpose,
catheters would seldom be used merely to stiffen or straighten the
barrel-assembly, as when having passed a tortuous stretch.
Limitation to a barrel-tube for the insertion of a cooling catheter
means that the conduction path for chilled air to the turret-motor,
the radial projection units deployed by thermal expansion wires,
and the recovery electromagnets is asymmetrical, gives less
effective conduction to the recovery electromagnets, and since the
material of the barrel-tube, even thin-walled, is thermally
insulative, necessitates the extension of the gas return path
perforations along the sides of the barrel-tube to include the
entire segment of the barrel-tube parallel to the area to be
cooled.
[3354] For these reasons, a center-discharge barrel-assembly with
its larger diameter central canal and ejection head cooling
catheter insertion channel is superior to an edge-discharge
barrel-assembly for thermal angioplasty. The effect of a fever on
clotting with clot-suppressing platelet blockers (antiaggregants)
in arteries or anticoagulants (`blood thinners`) in veins, and
dissolving (thrombolytic, fibrinolytic, `clot-busting`) drugs
(streptokinase; urokinase; tissue plasminogen activator as
tenecteplase or reteplase; recombinant tissue plasminogen
activator, or alteplase, anisolylated plasminogen activator, or
anistreplase) as conventionally administered for an angioplasty
warrants further research.
[3355] Disregarding the administration of such medication, which
infrequently produces significant bleeding complications Cote, A.
V, et al. 2001 and Jong, P. et al. 2001, cited shortly following
the section above entitled Objects of the Invention), to reduce the
thrombogenicity of the arterial wall when heated, a temperature of
90 degrees centigrade (Celsius; 194 degrees Fahrenheit) or more
serves to denature collagen and von Willebrand factor (Post, M. J.,
de Graaf-Bos, A. N., Posthuma, G., de Groot, P. G., Sixma, J. J.,
and Borst, C. 1996. "Interventional Thermal Injury of the Arterial
Wall: Unfolding of von Willebrand Factor and Its Increased Binding
to Collagen After 55 Degrees C. Heating," Thrombosis and
Haemostasis 75(3):515-519; Humphrey, J. D. 2003. "Continuum
Thermomechanics and the Clinical Treatment of Disease and Injury,"
Applied Mechanics Reviews 56(2):231-260; Bos, A. N., Post, M. J.,
de Groot, P. G., Sixma, J. J., and Borst, C. 1993. "Both Increased
and Decreased Platelet Adhesion to Thermally Injured Subendothelium
is Caused by Denaturation of von Willebrand Factor," Circulation
88(3):1196-1204; Borst, C., Bos, A. N., Zwaginga, J. J., Rienks,
R., de Groot, P. G., and Sixma, J. J. 1990. "Loss of Blood Platelet
Adhesion After Heating Native and Cultured Human Subendothelium to
100 Degrees Celcius," Cardiovasc Research 24(8):665-668).
[3356] Thermal angioplasty, or thermoplasty, windows, window-slits,
and window slots are microrouted or electrical discharge machined
into the sides of the proximal (rear) and distal (front)
muzzle-head shells in a center-discharge muzzle-head and the
proximal shell in edge-discharge or combination-form
barrel-assemblies. The window openings or apertures are then
covered over with silver or copper sheet which is inset or lapped
into the outer surface of the opening or openings to create an edge
that is flush to the surface of the muzzle-head body. The
turret-motor slit or slot heat-window slightly protrudes or stands
in relief of the surrounding surface, while the nose heat-window is
flush or filet fit.
[3357] The window overlays are bonded along the overlap with a
long-chained cyanoacrylate, or a DYMAX Corporation 200-CTH-series
cement not subject to liberate toxic substituents upon degrading.
To allow good slippage, or the noninjurious movement of the
muzzle-head body against the endothelium, the heat-windows are
masked for immersion (dip), plasma vapor, or sputter coating with a
thermal insulating polymer. A fluoropolymer is preferred for a low
coefficient of friction and little tendency for clinging to the
endothelium. Since to prevent a temperature gradient about the
heat-windo is impossible, the use of thermal insulation is intended
to better focus the heat.
[3358] Where the heat foci do not pass, a platelet blockade or
anticoagulant as appropriate reduces the risk of thrombus formation
due to temperatures that intervene between body temperature and 90
degrees centigrade (Post et al. 1996, Thrombosis and Haemostasis
75(3):515-519 cited above). While at 3 millimeters (9 French) in
outer diameter, most muzzle-heads will not allow any further
coating, for additional insulation, the polytetrafluoroethylene
coating on the outer surface of portions of the muzzle-head shell
other than those cut away for the heat-windows, slits, or slots may
be further coated with a thin layer of silica aerogel.
[3359] Further to reduce the number of components that would
consume precious space and an overall complexity that would
significantly increase costs:
[3360] a. Rather than to provide a local current-actuable
insulating layer or movable insulating cover in surrounding
relation to the heating elements (turret-motor and recovery
electromagnet housings), the momentary temperature rise-time is
discounted, platelet blockade or anticoagulant medication, which
can be delivered in higher than the circulating or systemic
concentration through a catheter passed through a neighboring
barrel-tube or service-channel (addressed below) depended upon to
minimize unwanted coagulation; and
[3361] b. The same rapid cooling catheter or cooling capillary
catheter (following section) is used in center and edge discharge
muzzle-heads within the range of common diameters (2.5-4.0
millimeters), the placement and interval of time using a specific
vortex tube or other means for supplying cold air required in each
instance to drop the temperature from 90 degrees centrigrade, or if
used for thermal ablation in a ductus other than vascular, then the
temperature that pertains, back down to body temperature (98.2
degrees Fahrenheit or 36.8 degrees centigrade) provided on a
specification sheet that is supplied with the apparatus for setting
the vortex tube timer, which interval of time has been
predetermined empirically based upon multiple trials.
[3362] The low thermal conductivity of the materials used; rate of
cold air delivery from the cold air gun, CO.sub.2 or NO.sub.2
cartridge; tight fit of the rapid cooling capillary catheter within
the passageway employed whether peribarrel space, gas-return path,
or spare barrel-tube used as a service-channel; and interval to
pressure equalization among the holes toward the distal end of the
cooling catheter is such that in a combination-form edge-discharge
muzzle-head as discussed in the section to follow, extension
proximally of the perforated distal segment of the fully inserted
rapid cooling catheter to the turret-motor does not result in a
significant lessening of the cooling effect at the
turret-motor.
[3363] VII2g(3)(d). Radial Projection Units
[3364] Radial projection units are lifting mechanisms that hold and
extend interchangeable tools, or tool-inserts, radially outward
from and about the periphery of a barrel-assembly muzzle-head or a
separate (special, dedicated) radial projection catheter, as
addressed below in the section of like title. The ability to extend
hypoendothelial or hypointimal injection needles and the cutting
faces of tool-insert bits, for example, from beneath the surface of
the barrel-assembly or separate catheter and then fully retract
these into this safe recess makes it possible to use sharp
implements and resume transluminal movement with little risk of
perforating or introducing incisions into the lumen wall.
[3365] Radial projection units can also aid luminal passage of the
barrel-assembly by releasing drugs to dilate or decongestant the
lumen. To avoid protrusons that could snag, gouge, or incise the
inner surface of the lumen, the radially outward edges of radial
projection units and the faces of the tool-inserts placed in these
follow the surface contour as seen in cross section. This is not
evident in longitudinal section, however. Tool-inserts such as
shavers or brushes are open-faced, any material having entered
expelled when the tool-insert is lifted. For use in the
bloodstream, a run-ahead protective embolic filter is deployed from
the nose of the muzzle-head or separate noncombination-form radial
projection catheter during any process likely to generate
potentially embolizing debris.
[3366] Radial projection circuits and units are either electrical
or fluidic, those electrical less requiring an increase in the
gauge and stiffness of the barrel-catheter. For this reason, only
electrical units are incorporated into the muzzle-heads of narrower
minimally and fully ablation or ablation and angioplasty-capable
barrel-assembliies. Fluid circuits and units are incorporated into
large muzzle-heads and separate combination-form radial projection
catheters, which can be slid over barrel-assemblies of matching
size at any time, as addressed in the section below entitled Radial
Projection Catheters. Generally, electrical circuits allow the
incorporation into small gauge barrel-assemblies and the
muzzle-heads thereof of side-looking (radially outward or lumen
wall facing) electrical tool-inserts where a fluid circuit would
not fit.
[3367] Electrical and fluid tool-inserts share and have unique
capabilities. Electrical tool-inserts can incorporate an actuator
but must heat syringe contents locally and have limited ability at
delivering fluids. A fluid injection tool-insert, or syringe
injector, for example, can continue to inject without the need for
repeated needle punctures. Fitting a tube the same in outer
diameter as the muzzle-head about a barrel-catheter significantly
affects pliancy or trackability, but depending upon its extent
proximally, can yield up to the entire intracorporeal length of the
barrel-assembly for incorporating tool-inserts. In small gauge
barrel-assemblies, these will usually be limited to electrically
operated units.
[3368] Self-contained electrical/fluid system-neutral syringes,
fluid system syringes, and fluid continuous-feed tool-inserts as
described below can all be used to eject into the lumen or inject
into the lumen wall any type medication or other fluid therapeutic
substance to include those specified in the section above entitled
Field of the Invention, and can do so at a preferred temperature.
Also ejectable by these means are lubricants, used with or without
the oscillatory operational mode of the turret-motor to pass
tortuous stretches along a vessel, for example, as addressed above
in the section entitled Turret-motor Operational Modes. Also
injectable are embolizing agents, molten protein solder of lower
melting point, and surgical cement, for example.
[3369] Such lumen side-looking injection of an embolizing agent
eschews the unwanted reflux and diffusion that can affect
nontargeted tissue while leaving the tissue intended inadequately
embolized (see, for example, Novak, D. 1990. "Embolization
Materials," in Dondelinger, R. F., Rossi, P., and Kurdziel, J. C.,
Interventional Radiology, page 295). Injection tool-inserts can be
kept from sufficient outward (radial) extension that the ductus
could be perforated, and a spring-strip beneath the lift-platform
assures that tool-inserts to include cutting, abrading, and
injecting are automatically retracted into the tool-insert housing
at the instant that power is cut off to the the tool or tools.
[3370] Tool-inserts can be blanks used as plugs in fluid unit not
to be used, push-arms, inert cutting bits, or controllable tools
that incorporate various mechanical, electrical, chemical, or a
combination of such components. Radial projection units can be used
to nudge the catheter in a desired radial direction, release
medication or other therapeutic substances into the lumen or inject
these into the lumen wall, heat or chill these substances, or
thermo- or cryoablate the lumen wall, as well as perform cutting
and other operations. Since the internal structure of these
tool-inserts is anteroposteriorly asymmetrical to perform as
emitters or aspirators depending upon the direction of fluid flow,
units in the same fluid circuit will emit or irrigate or aspirate
depending upon anteroposterior orientation in the circuit.
[3371] That is, reversing this orientation thus reverses the
action, whereas tool-inserts placed in separate circuits of flowing
in opposite directions perform the same action when
anteroposteriorly oriented alike. Reversal of flow through an
emitter-irrigator-aspirator tool-insert reverses its action from
emission or irrigation to aspiration and the reverse. Thus, for
antegrade or retrograde flow through the same fluid circuit, the
same kind of tool-insert if oriented in reverse will perform the
opposite action. Under higher pressure, an aspirator can be used to
recover a mispositioned miniball when the recovery electromagnets
are in use for another purpose, such as heating. An external magnet
is usually needed to abut the aspirator face-plate over the
miniball entry hole.
[3372] Units can be coordinated, such as by using one to inject a
surgical cement and another to apply heat at the site to accelerate
initial setting. Radial projection units as tool-insert lifting
mechanisms are either electrical or fluidic, neither as a rule
affording connection to a source of the other type power in order
to support a hypothetical tool-insert incorporating a component
requiring the other type power. Electrical and fluidic units can be
coordinated so that fluid units are used to irrigate and/or
aspirate a site under treatment by other fluidically or
electrically operated tool-inserts. Generally, differences in
function and performance characteristics are obtained through the
use of different interchangeable tool-inserts rather than by
building these into the permanent elements of the fluid circuit
where adjustment would be awkward.
[3373] Optimal functionality requiring that every unit have tool
lifting and retraction capability, all are designed to serve as
lifting mechanisms. Injectors must be projected beyond the
periphery of the muzzle-head or radial projection catheter, as
addressed below in the section of like title, and lifted as a
whole, whereas in emitters, lifting is of a plunger within the
tool-insert of which the body (housing, enclosure) is not lifted.
Extension is not necessary to eject a fluid into, aspirate from the
lumen or the endothelial lining of the lumen, or heat, for example.
However, most tool-inserts require extension during use, and most,
such as mechanical ablation and injection tools, must be retracted
to prevent incisions upon the resumption of movement. Therefore,
nonprojectability precludes the use of a given unit for a majority
of interchangeable tool-inserts wherewith to perform diverse
applications.
[3374] At the same time, the space available for incorporating
units into most muzzle-heads will be limited. For these reasons,
all units are made to project and retract, and all tool-inserts
must be usable in these units. Since resistance to lifting could
result in damage to the lifting mechanism, tool-inserts are not
made to completely fill the lift-shaft. Tool-inserts to serve as
blanks or plugs with a unitary body are recessed when not in use,
while others telescope a narrower lower into a wider upper part.
Tool-inserts which can remain level with the surface of the
muzzle-head, such as electrical and fluidic heaters, and which must
maintain connection to the electrical or fluidic circuit through a
base-plug, are made in two sections of which the lower or radially
inward, central, and slightly smaller telescopes up into the upper
larger or radially outward.
[3375] In self-contained disposable injection syringe tool-inserts
(injectors, piston or plunger syringe injectors), as described
below in the section entitled Self-contained Electrical/fluid
system-neutral Tool-inserts, to Include Injection and Ejection
Syringes, this action is essential to project and retract the
needle. To accommodate the lifting mechanism, an electrical/fluid
system-neutral inert bit or a fluidic flow-through or mechanical
syringe ejection tool-insert can be made either with a unitary body
that remains recessed within the lift-shaft when not in use and
raised during use or with a lower body section that rises or
telescopes up into a wider upper or radial section of the body that
remains stationary with its top or radial surface flush to the
surface of the muzzle-head or separate radial projection
catheter.
[3376] The top or radial surface of the latter remains closer to
the surface of the muzzle-head or separate radial projection
catheter and is less prone to accumulate debris. Lifting is
essential to raise an injection needle, brush, or shaving face into
contact with the lumen wall. The lifting mechanism consists of the
tool-insert holding and lift-platform and shaft, more detailed
descriptions of the lift mechanism and its control provided in the
sections below entitled Structure of Radial Projection Units and
Radial Projection Unit Control and Control Panels, Elecrical and
Fluidic or Piped, respectively.
[3377] In an nonpiped, that is, an electrically operated circuit,
the tool holding and lift-platforms are raised or projected by
delivering current to non-high temperature nickel-manganese-lead
high thermal expansion alloy wires (see, for example, Bauer, H. J.
1977. "Mechanical Motions in Small Inaccessible Volumes," Journal
of Physics E: Scientific Instruments 10(4):332-334; Radvel, M. P.
and Evdokimova, O. I. 2004. "Alloys with a High Coefficient of
Thermal Expansion Based on the Mn-Pd System," Metal Science and
Heat Treatment 16(5):403-405 [original in Russian 1974,
Metallovedenie i Termicheskaya Obrabotka Metallov 5:36-38]). While
close to the turret-motor and ferromagnetic, the securing in
position, disposition, and function of the thermal expansion wires
results in little interaction between these.
[3378] As shown in FIGS. 52a, 53a, 54, 55, and 56, each nonpiped or
radial projection unit 174 that is deployed and retracted
electrically consists of radially oriented lift-shaft or well 182,
opening onto the surface of the muzzle-head; tool-insert holding or
support (tool holder, tool holding frame) and lift-platform 176,
which rides up and down lift-shaft 182; and coiled thermal
expansion wire 177 along the floor of lift-shaft 182, used to raise
lift-platform 176. More specifically, lift-platform 176 is pan- or
tub-shaped as a holding and lift platform in FIG. 53 when the
tool-insert is secured by friction fit therein, but flat at the top
as a deck or lift-platform when retention within lift-shaft 182 is
by means of rotatable hold-down arms 186.
[3379] Since radial projection units will usually be subjected to
levering forces while in use and directed other than upwards,
retraction into lift-shaft 182 when lift-platform 176 is not
energized or de-energized is not left to gravity but by the fitting
of a base-plug into a small socket in the top of lift-platform 176,
making it a holding and lift-platform. When this plug is used
without hold-down arms 186 only to secure tool-insert 184 in place
rather than to provide connection to an electrical or fluid power
line, it is a dummy projection or dummy-plug without power
conductor; otherwise, it provides the electrical or fluid
connection to the line that carries the electrical or fluid current
use to operate internal components within tool-insert 184.
[3380] In a nonholding lift-platform, a small spring (not shown)
may be used to retract tool-insert 184. Alternatively, friction
fitting, screw-in, or snap-in engagement can be used to retain
tool-insert 184 within lift-shaft 182. Hold-down arms 186 in FIGS.
52a, 52b,54 thru 56, 59, 60, and 63 are positioned adjacent to
lift-shaft 182 on the surface of the receiving device, whether a
muzzle-head or radial projection catheter. In FIG. 54, for example,
interchangeable tool-insert 184 is retained within lift-shaft 182
supported beneath by tool-insert lift-platform 176 by hold-down
arms 186, which rotate around or slide as latch bolts into
depressions in the top of the tool-insert of like depth as those to
which hold-down arms 186 are fastened.
[3381] Thermal expansion wire 177 is illustrated as a simple coil,
but depending upon the coefficient of thermal expansion, may
require to be densely wound. Lift-shaft 182 seen in FIGS. 52a, 52b,
54 thru 56, 59, 60, and 63 in vertical section, and the
tool-inserts for use therein are usually rectangular in
cross-section but can be given any shape. The
piston-plunger-receiving component in an ejection or injection
tool-insert, as seen in the foregoing figures, is referred to as
the `barrel` and the intromitted component as the plunger,
regardless of cross section, whether circular, square, or
rectangular. A strip-spring is a band of springy material that is
used to impart elasticity to a joint between a platform or panel in
flush parallel relation to the strip-spring and a stationary
neighboring structure.
[3382] These are usually mounted for unidirectional function just
beneath the lift-platform to hasten retraction of the lift-platform
when the electrical or fluid lifting current is turned off. A
strip-spring interposed between two structures can be used to hold
the surfaces of these structures in flush relation with the joint
between these elastic. More specifically, the strip-spring is
fastened at its center to a stationery structure to one of its
sides. The strip-spring is a unidirectional device that when used
to cover over an opening in a fluid circuit serves as a
unidirectional fluid resistor. On the other side, the strip-spring
is fastened to a movable platform by rivets in the platform that
slide along slots in and towards the ends of the strip-spring.
[3383] Once a force separating the surfaces is removed, the
strip-spring will pull the platform into flush relation. The
restorative force of the strip-spring depends upon its material and
dimensions, which can be specified with exactitude, the more so in
disposable tool-inserts not subject to alteration from repeated use
or fatigue. The material properties of the strip-spring and the
length of the slots do not permit a degree of deformation, hence,
the elastic limit of the strip-spring, to be exceeded. The
strip-spring thus establishes a threshold force below which the
joint will not open. Provided the fluid is constrained from taking
another course and the fluid pressure is less than that necessary
to flex the strip-spring, the strip-spring will obstruct the fluid
from passing through a hole in the platform.
[3384] A fluid pushing against the platform with the necessary
force will flex the strip-spring separating the platform from the
stationary structure and expose the hole so that fluid will force
its way through the hole, here the entry to the base-plug. The
absolute cross sectional area of the equipment lumina are so small
that gravitational effects due to the rotational angle of the
muzzle-head or radial projection catheter are insignificant. A
two-way or bidirectional fluid resistor can consist of an
elastomeric slit membrane valve, which is a sheet of a synthetic
(nonallergenic) elastomeric material such as a silicone elastomer
containing a straight, X shaped, or stellate slit or slits.
[3385] When placed across a fluid conduit, the fluid must reach a
certain minimum pressure before the edges of the slit, or slits are
forced open creating a path for the fluid to pass through to the
other side. For fluids or greater viscosity, the membrane is cut or
die punched with perforations of variable cross sectional area over
a variable area of the membrane. A one-way or unidirectional fluid
resistor in the base-plug of a fluid tool-insert allows the
tool-insert to be used as an aspirator. Once such a break-seal or
push-through stopper is eliminated from the fluid path, however,
the tool-insert actuating pressure no longer confronts an
incremental threshold over the line pressure as would remain the
case with a two-way or bidirectional resistor such as a
slit-membrane.
[3386] Strip-springs made of more resilient spring sheet metal and
mounted to allow flexion to either side can replace elastic slit
membranes for use in tool-inserts that must aspirate and would
therefore clog. Membranes are is not sufficiently elastic to
replace a strip-spring for the purpose of retracting an injector or
cutting face, and while bidirectional, are readily clogged by
debris and thus unsuitable for use in tool-inserts that must also
be capable of aspiration as is preferred. Where rigidity rather
than elasticity are desired, a similar passable pattern is molded
or machined into a baffle plate of inelastic plastic or metal
sheet. The material of the sheet used to make any type of fluid
resistor or baffle and the dimensions and conformation of both
sheet and cut are widely variable, allowing the rate of
flow-through to be adjusted as necessary for the viscosity and
pressure of the channeled fluid.
[3387] The same pertains to any fluid resistor or baffle whether a
strip-spring, membrane, of baffle plate. Baffles are circular or
rectangular according to the path in which these are positioned.
When the circuit must be used with fluids of widely different
viscosity, plastic plates with different sized apertures are used
interchangeably. In tool-inserts, which must be interchangeable,
perforated plates are used as fluid resistors or baffles to adjust
lift-platform lifting force and rate of outflow through the
tool-insert into the lumen. The perforated passive fluid resistor
roof-plate would be a bidirectional resistor were it not hinged to
lift out of the way to allow debris to move in the retrograde
direction and to act as a venturi during aspiration as addressed
below. In tool-inserts that aspirate, these are mounted to
passively turn aside by an inflow.
[3388] In the permanent fluid unit lifting mechanism, which must
accommodate tool-inserts that are capable of aspirating, a
perforated plate hinged along the chamber outlet-directed edge is
used to roof over the outlet chamber as a fluid resistor during
antegrade flow. In retrograde flow (during aspiration), the extent
to which the inward edge of the plate can rise is limited. This
causes the fluid passing the aperture before the opening into the
tool-insert base-plug opened by the lifting of the inner or medial
edge of the plate to increase in velocity thus creating suction at
the opening into the plug. A initial charge or prefilled fluid
injection or ejection tool-insert must be discharged before the
tool-insert can be used for aspiration. When such tool-inserts are
used, an adjacent circuit must be used for aspiration, any unit not
to aspirate having been plugged with a blank tool-insert.
[3389] To avoid clogging, the plate is passively lifted out of the
way by a retrograde flow. For this reason, a barrel-assembly or
radial projection catheter, as addressed below in the section of
like title, having parallel fluid radial projection circuits is
preferred. Procedures that generate significant debris recommend
the use of a bipartite simple radial projection catheter or
barrel-assembly with multiple interchangeable combination-form
radial projection catheters each of which includes at lease one
fluid circuit. A baffle or filter ahead of the roof baffle to trap
larger debris is not preferred as inevitably clogged; however, if
the velocity of retrograde flow during aspiration is not too great,
the bottom portion of the outlet chamber will serve to trap
particles of greater mass that drop down to the floor.
[3390] Where larger sized debris is anticipated, the use of units
having deeper lifting mechanism chambers can avert clogging. Unlike
rotatory atherectomy, the debris here is larger and should not be
released into the bloodstream. Since aspiration or retrograde flow
must inevitably accumulate debris, whenever possible, operations
involving antegrade flow should always be conducted first; if
retrograde is followed by antegrade flow, debris can be propelled
forward clogging the circuit if not expelled our of the
tool-insert. However, flushing through the circuit, first with a
tissue solvent such as sodium hypochlorite (bleach) moderately
concentrated for quick effect, immediately followed by water,
allows antegrade flow to be resumed without the need to
withdraw.
[3391] Neither need the flushing process unduely detain completion
of the intervention. Since only the interior of the circuit
contacts the solution, the concentration can be greater, hence, the
duration for dissolution much reduced compared to the use of dilute
tissue disolution solvents in endodontic practice. The use of
sodium hypochlorite, for example, in higher concentration increases
the level of tissue toxicity, making it necessary to confirm that
the fluidic circuit is free of any leaks.
[3392] If a resumption in antegrade flow must follow aspiration,
then the circuit is flushed through with a tissue dissolving
solution (see, for example, Christensen, C. E., McNeal, S. F., and
Eleazer, P. 2008. "Effect of Lowering the pH of Sodium Hypochlorite
on Dissolving Tissue in Vitro," Journal or Endodontics
34(4):449-452; Clarkson, R. M., Moule, A. J., Podlich, H.,
Kellaway, R., Macfarlane, R., Lewis D., and Rowell, J. 2006.
"Dissolution of Porcine Incisor Pulps in Sodium Hypochlorite
Solutions of Varying Compositions and Concentrations," Australian
Dental Journal 51(3):245-251; Zehnder, M., Grawehr, M., Hasselgren,
G., and Waltimo, T. 2003. "Tissue-dissolution Capacity and
Dentin-disinfecting Potential of Calcium Hydroxide Mixed with
Irrigating Solutions," Surgery, Oral Medicine, Oral Pathology, Oral
Radiology, and Endodontics. 96(5):608-613; Zehnder, M., Kosicki,
D., Luder, H., Sener, B., and Waltimo, T. 2002. "Tissue-dissolving
Capacity and Antibacterial Effect of Buffered and Unbuffered
Hypochlorite Solutions," Oral Surgery, Oral Medicine, Oral
Pathology, Oral Radiology, and Endodontics 94(6):756-762; Okino, L.
A., Siqueira, E. L., Santos, M., Bombana, A. C., and Figueiredo, J.
A. 2004. "Dissolution of Pulp Tissue by Aqueous Solution of
Chlorhexidine Digluconate and Chlorhexidine Digluconate Gel;"
International Endodontic Journal 37(1):38-41; Yang, S. F., Rivera,
E. M., Baumgardner, K. R., Walton, R. E., and Stanford, C. 1995.
"Anaerobic Tissue-dissolving Abilities of Calcium Hydroxide and
Sodium Hypochlorite," Journal of Endodontics 21(12):613-616) and
water (see, for example, Motta, M. V., Chaves-Mendonca, M. A.,
Stirton, C. G., and Cardozo, H. F. 2009. "Accidental Injection with
Sodium Hypochlorite: Report of a Case," International Endodontic
Journal 42(2):175-182)) before resuming antegrade treatment.
[3393] Appurtenant of the lifting mechanism as the permanent part
of the circuit built into the barrel-assembly or radial projection
catheter, the use of strip-springs and of perforated plastic plates
to cover over the outlet chambers in a fluid circuit are addressed
in this section. By contrast, elastic membrane resistors are most
often used within the interchangeable tool-insert components of the
radial projection system, and are therefore addressed below in the
section entitled Fluidic Tool-inserts, to Include
Ejector-irrigator-aspirators and Injectors. Readily clogged by
debris, elastic slit membrane resistors are limited to use within
nonaspirating tool-inserts for the purpose of reducing the flow
rate of discharge during ejection or irrigation with a light
viscosity fluid.
[3394] While radial projection units per se only lift inert and
self-contained syringe-type tool-inserts and can additionally
provide electrical or fluid current to and/or through their
respective types of tool-inserts, the functions performed by radial
projection units cannot be addressed apart from the tool-inserts
these support, the two working as a unit. There are essentially
three types of tool-insert, 1. Mechanical, wherein a `plug`
extending downward from the base is not needed to fasten the
tool-insert inside the projection unit, so that this type is usable
in either type system, 2. Electrical, wherein the `plug` is an
electrical as well as a mechanical connector, and 3. Fluidic,
wherein the `plug` is a tube extension that is a fluid as well as a
mechanical connector. Mechanical, electrical, and fluidic
tool-inserts can be further categorized.
[3395] Mechanical tool-inserts that are self-contained as not to
require connection to and thus equally usable in either an
electrically or a fluidically controlled system, making these
electrical/fluid system-neutral. Any `plug` extending down from the
base, if present, serves only to better stabilize the tool-insert
in the projection unit. These include:
[3396] 1. Simple mechanical tool-inserts, such as inert bits with
shaving or abrading working faces that require radial extension
during, and retraction immediately following use.
[3397] 2. Compound mechanical, wherein the tool-insert, usually a
syringe, includes a mechanical element, such as a spring used to
release a fixed dose of medication or another therapeutic substance
into the lumen or inject it into the lumen wall. Electrical
tool-inserts, wherein the tool-insert base-plug is an electrical as
well as a mechanical connector for connecting an electrical
component enclosed within the tool-insert to a source of electrical
power: These include:
[3398] 3. Simple electrical, such as containing a heating element
for applying heat to the lumen wall.
[3399] 4. Compound mechanical-electrical, such as a heating coil in
a compound mechanical syringe.
[3400] 5. Compound mechanical-electrochemical, wherein, for
example, resistance to penetration posed by the lumen wall to a
flanged hypoendothelial or hypointimal injection needle is used to
close a switch that initiates a current used to heat a filament
which breaks down a barrier separating gas-generating components,
such as acetic acid and sodium bicarbonate, causing the contents of
a syringe to be expelled. Such a melt-barrier can also be used to
separate chemicals from a solvent that when added generates
heat.
[3401] 6. Compound electromechanical, wherein, for example, a
spring is released by passing a current through and melting a
restraining wire, such that the electrical and mechanical elements
are not one and the same.
[3402] 7. Electromechanical, wherein the tool-insert includes an
actuator such as a thermal expansion wire, polymer actuator,
electric motor, or vibrator, such that the electrical and
mechanical elements are one and the same. Fluidic tool-inserts,
wherein the tool-insert base-plug serves as a fluid as well as a
mechanical connector for admitting fluid from the control circuit
into and through the tool-insert to be delivered into the lumen
(ejector), the lumen wall (injector), or in a tool-insert capable
or additionally capable of aspiration, from the lumen to the line,
and if present, to power a component incorporated into the
tool-insert:
[3403] 8. Simple flow-through ejector-irrigator-aspirators,
injectors, and aspirators without an entry elastomeric membrane
slit valve or strip-spring as fluid resistance or regulator
covering the internal opening into the plug at the base of the
tool-insert, which thus passively and inseparably conduct fluid
from the line (fluid circuit, pipeline, supply line) to the lumen
from and in proportion to the extent to which the fluid pressure
raises the lift-platform and propels the fluid. In a fluidic
circuit that includes bypasses as described below in the section
entitled Fluidic Tool-inserts, to Include Ejectors and Injectors,
such a tool-insert, because it incorporates no fluid resistor,
allows fluid to flow through it when the line pressure is little
greater than necessary to close the fluid chamber partition
aperture spring-loaded swing type wafer check or strip-spring
mounted flapper valve closing the aperture and raising the
lift-platform. The lack of an internal strip-spring or slit
membrane also allows unrestricted flow-through in either direction,
making possible use as an aspirator as well without the need for
special spring valving to avoid clogging.
[3404] 9. Compound fluidic- and mechanical flow-through injectors
and ejector-irrigators (but not ejector-irrigator-aspirators)
having an entry elastomeric slit membrane, hard resin slit or
perforated fluid resistor, or strip-spring type of valve as fluid
regulator covering the internal opening into the plug at the base
of the tool-insert. Pressure in the line must first exceed that
required to raise the lift-platform, then the additional pressure
required to pass the entry elastomeric membrane slit or
strip-spring valve or fluid resistor in the base of the
tool-insert, allowing differential actuation of tool-inserts in the
same circuit. For use in an ejector-irrigator-aspirator, a
strip-spring would prevent intake flow, and a slit membrane would
clog (see next listed). The flow-through resistance is a function
of the viscosity and pressure of the fluid used.
[3405] 10. Compound fluidic-mechanical flow-through tool-inserts
having cutting faces with irrigation and/or aspiration integrated
that must remain projected while in use, then retracted for safety,
requiring a lift pressure setting strip-spring, and
ejector-irrigators that additionally function as aspirators which
use an internal strip-spring as a fluid valve regulator to set a
flow-past pressure and rate of discharge. To aspirate as well as
discharge and irrigate requires bidirectional function not afforded
by a strip-spring, and reasonable resistance to clogging not
provided by a slit membrane. Such function requires more complex
bidirectional valving that not only sets the threshold pressure for
rate of discharge for a fluid of variable viscosity in antegrade or
outward flow but allows retrograde flow without clogging over an
interval sufficient to complete the interventional procedure. Fluid
used to flush through the line during aspiration moves through the
circuit with negligible if any rising up into the tool-insert.
Various fluids can be used to irrigate with the same or different
fluids used to aspirate.
[3406] 11. Initial dose or front-loaded simple flow-through
ejector-irrigator-aspirators and injector-irrigators.
[3407] 12. Initial dose or front-loaded compound fluidic-mechanical
flow-through ejector-irrigator-aspirators and
injector-irrigators.
[3408] 13. Mechanofluidic--inert bit mechanical shaver or abrader
(brush) with integral irrigator.
[3409] 14. Mechanofluidic--inert bit mechanical shaver or abrader
with integral aspirator.
[3410] While distinguishable on the basis of function thus, a
single tool-insert can usually perform more than one function. For
example, the initial dose expended, an initial dose or front-loaded
injector can then be used as an intermittent or continuous
injector. Not extending a needle, an initial dose ejector, once the
initial dose has been expended, can be used not only as an
intermittent or continuous ejector, but as an irrigator. This not
only allows the different application of one and the same
tool-insert for different purposes without the need to withdraw and
reenter but also realizes economies and efficiency. Fluidic
tool-inserts that include electrical function and thus require
connection to a source of electrical as well as fluid power are not
preferred. The need for heating is avoided by delivering the fluid
already at the desired temperature.
[3411] With or without heating, oscillation to enhance the abrasive
or shaving action of an inert bit is accomplished with the
turret-motor or a neighboring electrical unit. Bits with paths for
irrigation or aspiration require insertion in fluidic units. An
abrading or shaving bit without integrated irrigation or aspiration
is used in an electrical unit with neighboring fluidic units or
service channel used for irrigation and/or aspiration. To avoid
clogging the delivery of fluid to projecting and emitting
tool-inserts, aspiration is relegated to a separate parallel
circuit with independent pump. Thus either individual abrading and
aspirating units can be used or electrical units can be used to
abrade with neighboring fluidic aspirators used to clear away the
tissue removed.
[3412] In some situations, aspirators can be used as suction cups
or suckers to hold the muzzle-head or radial projection catheter
against the lumen wall during injection by a projection unit
injector or barrel-tube delivered hypotube. However, excessive
suction force necessary to effect a seal is to be avoided. In the
vascular tree, special care must be taken to prevent intimal trauma
that would induce hyperplasia. The use of electrical tool-inserts
can also be coordinated with fluid delivery and removal through
barrel-tubes and the central canal, as addressed below in the
section entitled Coordinated Use of Aspiration and Piped Radial
Projection Units to Remove Diseased Tissue or Obtain Tissue Samples
for Analysis.
[3413] Electrical and fluid projection units and their respective
tool-inserts having unique as well as common capabilities,
depending upon the application, electrical and fluid circuits can
be incorporated into the same barrel-assembly. Then, however, for
simplicity in manufacture and use, fluid and electrical circuits
and components are not combined in the same units or tool-inserts.
While tool-inserts using both electrical and fluidic connection
would provide types of tool-inserts in addition to those listed
above, laying out the fluid and electrical circuits in parallel
allows using neighboring projection units from either circuit in a
coordinated manner, making hybrid tool-inserts that require
connection to both electrical and fluid circuits unnecessary.
[3414] Accordingly, electrical tool-inserts are used in electrical
but not in fluidic projection units and may contain mechanical,
chemical, electromechanical, or electrochemical but not fluidically
operated components. Electrical tool-inserts are lifted and
retracted electromechanically and contain an electrical component,
such as a heating element or vibrator. Electrically operated radial
projection units can be used to emit fluids only through mechanical
or mechanical and electrical syringe tool-inserts. These can
discharge a precise but small dose. Fluid systems can also use
self-contained or enclosed syringe tool-inserts that include no
electrical components, but can additionally use distinctively fluid
tool-insert that deliver fluids from the circuit. For use in blood
vessels, gases must be completely eliminated from the
tool-insert.
[3415] Thus, fluid tool-inserts are likewise prefilled with an
initial dose of the same medication as that to follow from the line
or another substance, such as water, and except for the tube
connector at the base, appear outwardly like enclosed syringes. Gas
discharged tool-inserts must be completely `airtight.` Once the
prefill substance is expended, however, the fluid syringe type
injector or ejector, unlike the enclosed syringes to which an
electrical system is limited, can conduct fluid from the line,
which can be fed fluid from a number of temperature controlled
reservoirs. This allows any amount and number of fluid substances
to be delivered in any sequence at any temperature.
[3416] By the same token, a fluid system cannot confine heating to
the treatment site as can an electrical tool-insert, and it is less
quick and flexible in terms of mechanical action within individual
tool-inserts. Fluid tool-inserts are lifted fluidically, that is,
electrohydraulically or electropenumatically, and when lifted, some
allow fluid from the line to pass through and out the working face
through apertures or hollow needles. Distinctly fluidic as opposed
to enclosed syringe-type tool-inserts are therefore usable only in
fluidi system projection units, and may contain mechanical or
chemical, but not electrical, electromechanical, or electrochemical
components. Due to the essentially fluidic or electrical function
of tool-inserts, those requiring connection to sources of both
fluid and electrical power are exceptional, those fluid operated
with inmate electrical heating element of this kind.
[3417] A radial projection catheter less limited in this regard,
nonprojectable units can be included, but radial units in
muzzle-heads are always projectable. The ability to inject a lumen
wall by means of radially oriented or side-looking hypotube
injectors, as addressed below in this section, has numerous
potential applications preparatory to and prophylactic upon
completing, an interventional procedure, to include implantation
with or without stenting. If the muzzle-head in a barrel-assembly
of larger gauge, such as for use in the gastrointestinal tract or
trachea and bronchi, is not large enough to accommodate the number
of radial projection units desired, additional units can be
situated anywhere about the intracorporeal periphery of the
barrel-catheter.
[3418] Radial projection and/or nonprojectable units can also be
incorporated into an ablation, atherectomy, or angioplasty catheter
without barrel-tubes as a separate and distinct device. Not having
to accommodate one or more barrel-tubes much less the gas diversion
channels required of a barrel-assembly, especially one for use in
the vasculature, such a catheter can be made narrower in gauge than
a barrel-assembly and much of its distal length can be used for
radial projection units. Morever, when made to the same diameter as
the equivalent barrel-assembly but without the ballistic component
(barrel-tubes, pressure relief channels), the area of the catheter
lumen becomes available to increase the depth of the unit
lift-shaft, so that self-contained syringe-type or injection
tool-inserts (injectors), for example, can contain and deliver
considerably more injectant.
[3419] Since units can be enlarged in the longitudinal and
circumferential directions and units placed along the entire
intracorporeal length of the catheter, the loss of depth is readily
compensated. A separate radial projection catheter with central
component such as a laser or rotatory cutter is referred to as a
combination-form radial projection catheter. As with a
combination-form barrel-assembly, the central component can be
permanently installed or used to install different interchangeable
cabled devices such as an atherectomy laser, endoscope, intraductal
ultrasound device, or rotational thrombectomy tool. Using a
combination-form radial projection catheter to ensheath a simple
pipe or radial discharge barrel-assembly places the ballistic
component in the central channel thus eliminating a central
component.
[3420] The `taller` unit shown in FIGS. 54, 56, 59, and 63, for
example, are thus suitable in a radial projection catheter or
barrel-assembly of large diameter and would be reduced in height
when incorporated into a smaller device. The larger area available
justifies the inclusion of nonprojectable units and freed internal
diameter allows the use of piped units where a barrel-assembly
would be limited to electrical units in vessels too narrow to admit
a barrel-assembly. In both electrical and fluidic systems, these
can be ejection syringe tool-inserts (ejectors) or heating
elements. Electrical ejectors can additionally heat the contents of
the syringe. Nonprojectable units in fluidic systems can deliver a
fluid at a specified temperature of if not perforated, use the
fluid to affect the temperature along the working face.
[3421] However, incorporating radial projection units into the
muzzle-head allows any number of medical functions to be applied to
the lumen wall at any moment in immediate coordination with
implantation without the need to withdraw and reenter. As in a
barrel-assembly, to contain the temperature, emitters both ejector
and or injector, made of low temeprature conductivity polymers, can
additionally be insulated as can the supply line in a fluid system
with an insulative coating. The lowering of injectors when not in
use also reduces heat transfer. Ejectors can be controlled thus
likewise. Both syringe and flow-through type radial injectors can
be used to introduce substances preparatory to administering
medication, other medication, or implantation, the latter not
limited to the volume of fluid contained.
[3422] Implantation preparatory substances include, for example,
medial tumefacients or swellants and tissue adhesive-hardeners or
binder-fixatives. The placement of radiation seed implants with a
barrel-assembly is ballistic. The two major types of radial
projection unit, electrical or nonpiped, without connection to a
fluid pipeline (line, supply line, conduit), and the fluidic or
piped, are described below under the heading Structure of Radial
Projection Units. Tool-inserts that do not require connection to a
source of electrical or fluid current through the projection unit
can be used interchangeably in either electrically or fluidically
operated units of like size.
[3423] These include passive or inert tools that consist of a
cutting head used to ablate tissue from the lumen wall by shaving
or abrasion at body temperature, and syringes that release fluid
stored within these. Other tool-inserts require connection to an
electrical or fluidic line. Some functions can be performed only
with one or the other type connection. Such actions that can be
performed electrically can be accomplished within barrel-assemblies
of smaller diameter, allowing application to narrower arteries, for
example. Heated cutting heads and blank face hotplate tools can be
either electrical or fluidic, while electronic (thermoelectric,
Peltier effect) microrefrigeration, early in development and
demanding unaccommodateable heat sinks, must be fluidic.
[3424] Electronic refrigeration is addressed above in the section
entitled Rapid Cooling Catheter and Cooling Capillary Catheter for
Cooling Heated Turret-motor, Electrically Operated Radial
Projection Unit-lifting Thermal Expansion Wires and Heaters, and
Recovery Magnets. Other electrical tool-inserts can incorporate
electromechanical or electrochemical means to raise the working
face with greater force or to a greater height, or electroactuator
means to move the working face in relation to the treatment site.
Fluidic tool-inserts can pass through fluid from the line into the
lumen, or if provided with a hypointimal or hypoendothelial needle,
inject the fluid into the lumen wall. Only tool-inserts for
insertion into the units connected to a fluid supply line can
additionally be used to emit a fluid on a continuous or
intermittent basis or fluid that has been chilled.
[3425] A piped system and tool-insert can be used to deliver
different liquids and/or gases from the line to the treatment site
at the most effective temperature and/or to aspirate ablated
tissue. and abrasive action can be accelerated by quickly rotating
the muzzle-head with the turret-motor (qv.), which can accede to
oscillatory frequency, or by reciprocating the barrel-assembly
transluminally by hand if not with the aid of a linear positioning
stage. Electrical tool-inserts for use in larger electrically
operated projection units such as for use in the gastrointestinal
tract or airway can incorporate a wobbling or reciprocating motor
to accelerate the cutting action. Also usable with either type
lifting mechanism are self-contained ejectors and injectors or
syringes which contain rather than draw the fluid from the
line.
[3426] Even though no tooling (cutting, brushing, or injection)
function is performed, flat-faced tool-inserts, or blanks, such as
are used as push arms, as well as fluid emitting tool-inserts in
piped units are referred to as tool-inserts. Different tool-insert
are used to ablate, angioplasty, or deliver fluid at the treatment
site at a controlled temperature by conducting heated or chilled
liquid or gas from a cylinder attached at a side-socket (qv.) or
end-socket (qv.), or in the case of an ablation or ablation and
angioplasty-capable barrel-assembly, from a self-contained internal
circuit that includes a pump and reservoir, for example. Electrical
units are elevated or projected into working position electrically,
while piped or fluid-operated units are elevated by the force of
the fluid against undersurface, that is, the inward or medial
surface of the tool-insert holding and lift-platform.
[3427] The action using a liquid is hydraulic, and using a gas,
pneumatic. Hybrid units that use fluid to raise the lift-platform
and also connect electrical tool-inserts to a power source are
unpreferred as needlessly complicated compared to electrical units.
Electrical or fluidic, the distance lifted is proportional to the
current through the pipeline. Additional lift by the radial
projection unit itself as a lifting mechanism rather than by a
device built into the tool-insert can be obtained by incorporating,
for example, the scissors linkages described below in the section
entitled Extended Projection Scissors Lift-platform Mechanisms. The
lift-platform receptacle or socket in an electrical unit engages
interchangeable tool-inserts electrically as well as
mechanically.
[3428] Enabled only while in the raised position, the electrical
tool is wired and controlled as a subcircuit of the expansion wire
used to raise the lift-platform. As seen from above, the
lift-platform socket in a fluid system is the same as that in an
electrical system but always passes entirely through the
lift-platform.
[3429] Since the fluid circuit is a permanent feature of the
barrel-assembly or radial projection catheter, the resistance to
lifting among units in the same circuit is best kept uniform.
Differential lifting among the individual tool-inserts is then best
accomplished by factors built into these. Differential actuation
along the same circuit allows cutters, injectors, ejectors to be
actuated before or after heating or chilling tool-inserts, for
example.
[3430] To provide differential lifting among units in the same
fluid circuit, the opening to the orifice (opening, ostium) leading
up into the base-plug is covered over with any of several
resistance. A one-way (unidirectional) resistance used where
transition to aspiration is not required is generally a
strip-spring covered orifice, break-away plug, or break seal.
Two-way (bidirectional) resitances are usually slit-membranes or an
offset strip-spring covered orifice. Strip-spring covered orifices
admit fluid from the line up into the tool-insert only when the
line pressure is sufficient to flex the strip-spring allowing fluid
to enter the orifice, flow through the tool-insert, and out the
working face.
[3431] In electrical tool-inserts, which are incapable of
aspiration, the need for bidirectionality is not a factor and
strip-springs used for differential resistance to lifting. Whether
in a barrel-assembly or separate radial projection catheter, where
a one-way resistance is used to establish a syringe discharge
threshold pressure, aspiration prior to emission or the resumption
of emission following aspiration is accomplished through use of a
second parallel fluid circuit. The continuous delivery through the
tool-insert of fluid requires first that the pressure in the line
is sufficient to pass the strip-spring closing off the bottom of
the lift-platform and second, the membrane slit or strip-spring at
the inside opening to the base-plug.
[3432] However, in tool-inserts to additionally function as
aspirators, alternative internal spring valving or regulating means
are necessary to allow bidirectional operation without clogging.
The radial projection unit can remain vacant until the line
pressure exceeds the restorative force exerted by the lift-platform
strip-spring. If exceeded while vacant, fluid will leak from the
line out of the unit. If filled with an emitting fluid tool-insert,
then the additional pressure necessary to overcome the ostial
strip-spring must be exceeding for fluid to pass through the
tool-insert. The delivery of heated and chilled gases and liquids,
which may be fed to continuous or intermittent fluid ejectors and
injectors or to closed surface tool-inserts for cryogenic or
thermal use will alter somewhat the pressure at which each of these
strip-springs yield.
[3433] A fully self-contained electrically operated tool-insert
such as a heater, which draws power from a circuit independent of
that supplying the electrically operated lifting mechanism, can
operate independently of the lifting mechanism. However,
self-contained compound mechanical syringe ejectors or injectors
when used in an electrically operated radial projection system must
be raised to function. In a fluid system, the tool-insert is
usually both lifted and supplied with the ejectant or injectant by
the fluid line. Such fluid tool-inserts are not self-contained.
[3434] Instead these function as dependent upon the lifting
mechanism such that the rate of fluid release through the
tool-insert is usually proportional to the pipeline pressure and
thus the degree of lift. Thus, both self-contained or syringe and
fluid transmitting type ejectors and injectors require to be lifted
in order to discharge fluid. Whereas electrical systems operate
these tool-inserts as a function of raising them, fluid systems do
so only once the tool-insert has been being raised. While the
reasons differ, the use of injectors and interchangeable ejectors
is indissociable from operation in the raised position. However,
minimal extension at low fluid pressure need not disable
tool-insert use in a fluid system.
[3435] Any one tool-insert for insertion into a piped unit may
require only to:
[3436] 1. Be lifted into working position once the fluid attains a
threshold pressure and thereafter remain extended to a distance
proportional to the fluid pressure, then retract when the pressure
drops below the lifting pressure, or 2. Expel fluid continuously
once the fluid attains a threshold pressure and discharge or
release the fluid in proportion to any higher pressure, or might be
used to
[3437] 3. Deliver an injection at a threshold pressure. In order to
allow any unit along the pipeline to accommodate a fluidic
(flow-through, non self-contained) ejector or injector, every fluid
tool-insert holding and lift-platform has a hole in its underside
that is kept closed by a tiny spring-loaded strip-spring valve that
can only be opened by a short pipe that extends down from the base
of a fluid delivering tool-insert.
[3438] Opening the spring valve then allows fluid to pass into the
tool-insert from the pipeline, through the tool-insert, and out the
perforation or needles on the tool-insert working face. Fluidically
operated tool-inserts that are only to be lifted into position and
not emit fluid do not have such a projection. Two types of ejection
or injection tool-inserts can be used in a fluidic system, one
unique to such a system, the other equally usable in an electrical
system. The fluid type allows fluid from the pipeline to enter
through a projection in the base that allows fluid in the line to
enter, flow through the tool-insert (syringe-insert, syringe,
injector), and out the face perforations or one or more
needles.
[3439] A fluid injection or ejection syringe is capable of
delivering the injectant or ejectant continuously or intermittently
up to the amount of fluid available in the reservoir. External and
cartridge refilled internal reservoirs allow unlimited delivery. An
ablation or ablation and angioplasty-capable barrel-assembly with
one or more internal fluidic circuits can incorporate multiple
completely enclosed, heated, and insulated reservoirs, to include
one containing distilled water for flushing the line before
switching from one medication or other fluid reservoir to another.
Refillable, refill cartridge-accepting, and switchable reservoirs
overcome limitation in the amount of each fluid available.
[3440] The alternative is to draw fluid from an external reservoir
or reservoirs, which eliminates the need for insulation, but
tethers the barrel-assembly, which can hinder free manipulability.
Fluid injectors can also be classified on the basis of whether
these deliver the fluid whenever the line pressure is sufficient to
overcome the resistance posed by an extension leaf spring in order
to raise the unit lift-platform or the pressure must additionally
exceed that necessary to overcome a second resistance whether posed
by a push-through stopper, or break-away plug, break seal, or a
second strip-spring that is offset and mounted to respond in the
opposite direction.
[3441] Unlike push-through stoppers and break-seals, which are
eliminated, a strip-spring covered inlet in the tool-insert
base-plug can be used repeatedly. Unlike slit-membranes which are
bidirectional, strip-springs are unidirectional. It therefore
allows the fluid in the line to be changed while the ejector is not
in use or the injector remains hypointimal or hypoendothelial.
While usable repeatedly, however, a unidirectional fluid resistor
prevents aspiration through the same tool-insert. The
unidirectional limitation of a strip-spring covered fluid path can
be overcome by providing a second passageway with the resistor
mounted on the opposite side. Perforated plates and slit-membranes
are examples of bidirectional fluid resistors.
[3442] Rather than to introduce nonuniformities among the lifting
mechanisms in the same circuit, the differential lifting of
injectors, for example, is accomplished by incorporating a
mechanical or fluid resistor in each that yields to a different
degree of force. The lifting pressure of a fluid tool-insert is set
by the resistances of the chamber partition inlet valve, which
belongs to the unit, and any fluid resistor in the tool-insert
base-plug, which is included in the interchangeable tool-inserts.
Of these, either or both can be varied in resistance or eliminated.
The valve is a cupped flapper-stopper mounted at the end of a
spring stainless steel arm or a swing type wafer check valve with
the convexity positioned in front of the aperture that allows fluid
to pass directly from the inlet through the partition to the outlet
chamber.
[3443] When units in the same fluid circuit are preferably variable
rather than uniform in response, the self-closing valve in front of
the inlet or pump outlet side of each chamber partition is varied
in resistance. Reciprocally, aspiration through ejector-aspirators
can be actuated at different pressures by varying the resistance of
the self-closing valve on the opposite side of the partition. A
subactuating idle pressure allows circulation through the line and
thus a quicker tool-insert response time. This self-closing valve
is riveted to the side of the inlet chamber by means of a angle
bent compression band of stainless spring steel. Since the material
and dimension of the strip can vary widely, a wide range of
restorative or closing force is possible.
[3444] Fluid current that presents a closing force that exceeds the
restorative force or resistance of the spring arm causes the
stopper to close the hole, leaving the extension strip-spring in
the chamber ceiling as the path of least resistance, so that the
tool-insert is lifted. This results in three levels of pressure:
sublifting, lifting, and fluid emitting. As fluid units are
designed to aspirate as well as actuate, a stopper of opposite
placement is positioned on the antegrade outlet or retrograde inlet
chamber. This second spring can be a helical compression spring, or
depending primarily upon the displacement desired, a leaf,
elliptical, or full elliptical compression spring, for example.
This spring is usually situated between parts of the injector
corresponding to the thumb rest and barrel bottom of a hypodermic
syringe.
[3445] Leaf and elliptical springs are usually paired to either
side of the extrabarrel portion of the plunger, whereas helical
springs surround it. Ejectors and injectors for use in either
fluidic or electrical units of a given size do not deliver fluid
from the pipeline but like full sized syringes, contain a finite
amount of ejectant or injectant which can be delivered continuously
or intermittently. This type can be disposable or hold refill
cartrdiges. When usable to deliver multiple individual injections
in succession, a single injection or syringe tool-insert, because
it still contains the liquid it discharges rather than draws the
liquid from the pipeline is still referred to as a single injection
type notwithstanding the fact that it too can be used
intermittently.
[3446] Both injector types are pressure actuated, so that serially
connected injectors with only the lift-platform strip-spring
discharge at the same pressure with a medically insignificant time
delay from one to the next moving downstream. By including a second
spring within the individual injectors, different pressures in
excess of the pressure to overcome that of the lift-platform are
established. Adjusting the dimensions and material of this second
spring internal to the tool-insert thus allows the differential
control of the individual units along one and the same electrical
or fluidic circuit; it is thus unnecessary that differently
functioning units be provided with a dedicated circuit.
Differential capability allows simultaneous or sequential ejection
or injection by tool-inserts in the same circuit, for example.
[3447] Control in this manner optimizes the extremely limited space
available in a barrel-assembly meant for use in the vascular tree,
and can be used to govern the absolute threshold force to actuate
each unit, the sequence in which the injectors or other
tool-inserts along the line are raised into working position and
then discharge or otherwise function, and the amplitude or extent
of this function. Injectors proximal to the pump that are more
resistant can be made to discharge or otherwise function later than
injectors farther downstream which discharge under less force.
Electrical tool-inserts can incorporate addtional means
electromechanical and electrochemical for affecting the force of
actuation and sequence of operation along one and the same circuit,
as addressed below in the section entitled Electrical Tool-inserts,
to Include Gas Discharged Injection and Ejection Syringes.
[3448] The only difference between continuous delivery and one-time
at pressure injectors is that the continuous type uses the
strip-spring base-gate to allow fluid from the pipeline to flow
through and out the needles or face perforations, whereas the
single-injection type does not admit and inject fluid from the
pipeline at all, but rather uses the pressure in the line to raise
the strip-spring base-gate to admit fluid from the line once the
expulsion pressure of the single-use or refillable cartridge that
constitutes the tool-insert has been reached. The single injection
type can thus be used in either an electrical or fluidic system of
the same size. Exposure of the cartridge bottom plunger-plate to
the fluid entering from the line at the pressure set by the
strip-spring gate forces the plunger to expel the liquid contents
of the cartridge through the openings at the working face and onto
or into the lumen wall.
[3449] Because the liquid is contained locally within the
tool-insert or the refill cartridge within the tool-insert rather
than drawn from a pipeline, electrical units can also be used to
position radial ejectors and injectors. As addressed below, these
tool-inserts can be internally compartmentalized to deliver
successive injections of the same substance at intervals, the same
substance at different concentrations, or different substances such
as medications upon exposure to increasing increments of pressure
so that the moment when each is injected can be controlled by
adjusting the line pressure. This becomes necessary when the
muzzle-head, because its length must be kept limited for reasons of
trackability and distal reach for treatment, cannot incorporate a
sufficient number of radial units to deliver the number and type of
medications desired.
[3450] Since each injector, whether a spring released
self-contained or fluid syringe, is actuated by pressure in the
fluid line, and this actuating pressure is readily set by the
materials and dimensions of the unit self-closing fluid chamber
valve and the tool-insert base-plug fluid resistor, fluid
expulsion, such as injection or syringe tool-inserts can be made to
act in any sequence regardless of type. Depending upon the
application, this can be significant. In the continuous delivery at
pressure-type, once the tool-insert holding and lift-platform has
been raised, a second strip-spring or similar valving mechanism
such as a spring loaded damper-like butterfly or poppet pressure
valve at the base of the tool-insert is used to control the
relation between the fluid pressure and the rate of fluid flow
through the tool-insert.
[3451] When engaged by a blank, the lift-platform is raised in
proportion to the resistance posed by the pipeline strip-spring to
the instantaneous pipeline pressure. The use of different materials
in different dimensions to make the strip-spring makes establishing
a desired restorative force, hence, lifting characteristic,
uncomplicated. Piped tool-inserts having perforations or hypotube
nozzles include in their base an internal strip-spring or similar
mechanism which serves as a second-order valve. With this
second-order strip-spring omitted, the tool-insert passively
discharges fluid in proportion to the fluid pressure used to raise
the lift-platform and therefore proportionally to the degree of
lift. That is, the rate of emission would varies as the
current.
[3452] The incorporation of a second strip-spring in the base of
the tool-insert isolates the rate of fluid release from the degree
of lift; however, emission is still dependent upon lift and
nonfunctional unless at lease some degree of lift exists. For
practical purposes, this sufficiently approximates independent
variability. If a piped unit tool-insert provides a passage with a
spring-loaded valve entry leading from an aperture in the
lift-platform through the valving mechanism and through a hole or
holes in the base of the tool-insert, then fluid passed through the
pipeline can be released through perforations or nozzles
(hypotubes) in the tool-insert faceplate.
[3453] The hypointimal or hypoendothelial injection of medication,
an implantation-preparatory ductus wall tumefacient as addressed
above in the section of like title, or some other fluid through a
fluid tool-insert can be performed in either of two ways. A
constant output pressure pump and reservoir are used to deliver the
fluid through the lift-shaft strip-spring and tool-insert base
strip-spring or alternative injection or syringe tool-insert base
gating device at a pressure or flow rate set by the pressure
setting and the passing pressure or gauge of the hypotubes or
nozzles. In the continuous delivery at the designated pressure mode
of delivery, the unit can be stepped along at intervals to inject
the fluid intermittently into a longer segment of the lumen
wall.
[3454] There is thus an initial threshold pressure that must be
reached before any of the injection or syringe tool-inserts or
injectors pass the fluid, after which the line pressure and
resistance to fluid entry of the individual injector determines
which injector or injectors pass fluid, allowing a prescribed
injection sequence to be established by selecting injectors having
an entry or gating resistance proportional to the pressure for
passing. To allow the use of an external hand-held electromagnet to
draw the hypointimal or hypoendothelial injection needles or
hypotubes up against and penetrate the lumen wall with minimal
field strength, the needles of both continuous and single injection
or syringe tool-inserts must contain ferromagnetic material whether
a magnetic stainless steel or a polymer containing iron powder.
[3455] As the fluid is injected, the pump takes up more fluid from
the reservoir to maintain constant pressure. The extent of
treatment is limited only by the amount of fluid available from the
reservoir. Filling the pipeline with costly medication of which
little is to be injected is not done; costly medication is
introduced by means of a tool-insert configured as a hypointimal or
hypoendothelial injection device or injector which is disposible or
accepts refill cartridges. A threshold force exerted against the
tool-insert base breaks a seal or releases a catch that frees a
spiral compression spring seated within the tool-insert base to
suddently drive the base upwards, ejecting the fluid.
[3456] The restorative force due to the thickness and material of
the base strip-spring, the seal, or a tripping device determining
the pressure at which fluid is allowed to pass and be injected,
each tool-insert can be selected for discharge at a specific fluid
pressure. If necessary, each unique injectant includes a
distinctive contrast dye. Adjustment of the pressure thus allows
the different tool-inserts to be infused into the lumen or injected
into the lumen wall at the time desired, allowing injection in a
preferred sequence. It will now be seen that any one tool-insert
can be used to deliver a single dose, or if not actuated by a
second order strip-spring, be made to release or inject medication
intermittently by this means. Thus, injection or syringe
tool-inserts, for example, can differ from one radial projection
unit to the next.
[3457] This makes the administration of the same or different
single-dose medication and injection that continues so long as the
pressure is high enough freely intermixable. Since each tool-insert
injector or group of injectors whether of the continuous or single
discharge type is differentially actuable simply by adjusting the
pump pressure, the differential injection and/or infusion of
medication can be coordinated with controlled timing.
Alternatively, a service-catheter with plunger and hypotube
injection tip passed down a barrel-tube as service-channel The
medication occupies and is ejected from the distal end of the
service-catheter. The onboard angioplasty control panel of an
ablation or angioplasty barrel-assembly with self-contained fluid
moving system includes a pressure control and gauge.
[3458] Electrically operated units are not associated with a
pipeline for lifting or fluid delivery and are not used to emit a
fluid or chill a blank tool-insert face plate. However, like fluid
units, electrical units can heat when the tool-insert contains a
heating element. Piped units are used with blank or closed-face
tool-inserts to change the temperature at the tool-insert
face-plate, or with perforated or nozzled face-plates to emit the
fluid for ejection or injection. Since with a blank, the preheating
or prechilling temperature of the fluid used determines the
temperature over the face-plate, separating the lifting from the
tool working function is unnecessary. Generally, fluidically
elevated units are used with perforated or nozzled tool-inserts to
deliver and/or aspirate fluids as a side function consistent with
the lifting means.
[3459] In a fluidic unit, the need to vary lift and descent
independently of the rate and timing of fluid ejection or
aspiration would not appear to justify hybrid electrically operated
units that include fluid lines to and from perforated or nozzled
tool-inserts. Aspiration with piped units supported by a full
circuit pump is by disconnecting the positive or pressurizing
output line of the pump while leaving the return line connected to
the unit pipeline. Ablation and ablation and angioplasty-capable
barrel-assemblies are preferably self-contained with no tethering
to a separate apparatus. When not required to deliver or recover an
unlimited volume of a liquid, for example, fluid circuits are
preferably incorporated into the barrel-assembly entirely, to
include the fluid pump, reservoir, manifold, and electrically
operated valves.
[3460] These are usually located in the power pack with a proximal
portion configured as a pistol or similar hand-grip having the
control panel mounted to its topside, for example, to avoid the
need for right and left-handed models. Combination-form
barrel-assemblies are ablation or angioplasty-type
barrel-assemblies, but usually require at least intermittent
connection through a cable to a remote console. Unperforated or
blank tool-inserts in piped radial nonprojectable units can be used
for cryoplasty or thermoplasty. Nonpiped or electrical units are
always projectable but unlike piped units, need not be projected
even slightly during tool use.
[3461] When perforated, the liquid or gas is emitted out of these
apertures into the lumen or onto the surface of the lumen wall, and
when nozzled, into the lumen wall. Radial projection unit
side-sweeper type tool-inserts or brushes have no precedent in
previous transluminal shaving or abrading devices such as
directional, rotational, or orbital atherectomy devices, brushes
meant for use to clear hemodialysis grafts, such as the Micro
Therapeutics-Castaneda over-the-wire brush (Castaneda, F., Li, R.,
Patel, J., DeBord, J. R., and Swischuk, J. L. 2001. "Comparison of
Three Mechanical Thrombus Removal Devices in Thrombosed Canine
Iliac Arteries," Radiology 219(1):153-156), Cragg brush (Dolmatch,
B. L., Casteneda, F., McNamara, T. O., Zemel, G., Lieber, M., and
Cragg, A. H. 1999. "Synthetic Dialysis Shunts: Thrombolysis with
the Cragg Thrombolytic Brush Catheter," Radiology 213(1):180-184)
or any other brush-like device.
[3462] Brush-configured tool-inserts have individual projections or
bristles that can vary widely in flexibility and have tips that
differ in conformation. With the barrel-assembly moved manually,
brush-configured tool-inserts can be extended to shave or abrade
diseased tissue along the lumen wall, for example. Inert bit
inserts with flat outer surface and rounded edges, or blanks, are
used as pushing arms to force the muzzle-head in the opposite
direction, to plug off or seal unused fluid units that would
otherwise emit fluid at a threshold pressure, and to test for leaks
in manufacture and prior to use when the blanks are to be used
during the procedure.
[3463] Side-pushing action or nudging can be used to allow more
blood to pass, to urge a tool-insert toward a preferred radial
position or arc, to cause, for example, a brush or injection or
syringe tool-insert on the opposite side to bear against the lumen
wall with greater force, or to aid in steering. A more detailed
description of nonpiped, or electrical, and piped, or fluidic,
radial projection units is presented below in the section entitled
Structure of Radial Projection Units. As shown in FIGS. 52a, 52b,
54, and 59 as exemplary for the two differently controlled types,
tool-insert receiving units include a lift-shaft 182 containing
tool-insert holding and lift platform 176 and are situated about
the periphery of muzzle-head as 174 in FIG. 49, for example,
between the front of turret-motor housing 61 to the rear, and
elastomeric segment of convoluted tubing that serves as flex-joint
(flexible joint) 111 to the fore.
[3464] Lift-shafts 182 are thus concentric to and distally
coterminal with barrel-catheter 44 at the level where
barrel-catheter 44 is joined to convoluted segment 111. In larger
embodiments, units can also be situated about recovery
electromagnet 65 housing. Hypothetically, in barrel-assemblies for
use in blood vessels, situating units about the magnet assembly
would place tool-inserts distal to the muzzle-ports for removing
plaque when the barrel-assembly is moved forward. However, few
vessels present sufficient internal diameter to allow a suitable
path for electrical connection to nonpiped units, much less a fluid
line for piped units. Provided the units contain no ferromagnetic
elements, placement thus is unhindered by the effects of the
tractive force and heat generated by the magnets on the lifting
mechanism.
[3465] The barrel-assembly readily reversed in direction, ablative
action can be readily accomplished with aspirating piped units
situated just behind (proximal to) the flex-joint, with the
deployment of an embolic trap-filter optional. The number of radial
projecton and nonprojectable units is increased by lengthening the
flex-joint segment and/or by increasing the arcuate extent of
separate units up to complete encirclement of the muzzle-head. For
optimal use of the available space, adjacent units are rectangular
in radial cross-section. The radial projection unit tool-inserts
are inserted into lift-platforms each of which rises and descends
within its own lift-shaft.
[3466] Individual units can also be made wider in relation to the
long axis of the barrel-assembly, that is, extended
circumferentially in arc, and provided with a tool-insert holding
lift-platform that accepts multiple tool-inserts in adjacent
relation. However, separate lift-platforms make it possible to
control those along a given circuit or pipeline independently or in
coordination with neighboring units. To aid observation, radial
projection units can be marked with bright contrast, such as
Danfoss Tantalum Technologies Danfoss Coating.RTM.. The arrangement
of consecutive or in-line (series connected) units along a given
line in relation to those in another line is unlimited with the
exception that piped units must be situated to allow for clearance
of the line. The sides of the lift-platform are made as low in
friction as possible and to fit flush or `airtight,` hence
leak-proof, to the sides of the shaft.
[3467] In-line units are connected sequentially along a single
line, or in series, and operate substantially in unison, the time
delay moving down line being proportional to the magnitude of the
current, which should be increased to the point that this delay
becomes too slight to have any practical significance. The units
along such a line can be equidistant or at unequal intervals, alike
or unlike in dimensions, retain the same or different type
tool-inserts, and units along different electrically or fluidically
operated lines can be interspersed. In some nonpiped and in piped
units as shown in FIGS. 52b, 59, 60, and 63, lift-platform 176 is
forced upwards against the restraining (retracting, depressing,
lowering, seating) force exerted by thin flat strip-spring 187,
which is fastened at both of its ends to the underside of
lift-platform 176 and at its center to the top of inflow (inlet,
ingress, entry) chamber 194--outflow or egress chamber 195
compartmental partition 188.
[3468] Inflow-outflow compartmental partition 188 is vertically
divided into upper portion 189 and lower portion 190 to allow flow
through its center until the pressure of antegrade (forward,
anterograde) fluid movement drives inflow flapper valve or spring
plug 191 to stopper or plug the inlet, or the pressure of
retrograde (reverse, backward) flow drives reversed inflow flapper
valve or spring plug 192, against the communicating hole aperture
193 created by the division of partition 188 into upper portion 189
and lower portion 190. The restorative force of strip-spring 187 is
exceeded by the upward driving force of the thermal expansion wire
in nonpiped units and the pressure of the fluid in piped units.
[3469] Strip-spring 187 consist of a band of springy nonmagnetic
spring stainless steel (stainless spring steel), which austenitic,
is virtually nonmagnetic, or a polymer with a similar restorative
characteristic, and is sufficiently wide to prevent the nonlevel or
lopsided raising and lowering of lift-platform 176. Since the
restorative force exerted by strip-spring 187 is widely variable by
changing its thickness and/or material, an electrically (thermal
expansion wire) controlled piped unit that failed to raise
lift-platform 176 when a lower pressure is in use is unnecessary.
Strip-spring 187 is included in nonpiped electrically operated
units for automatically retracting lift-platform 176 as thermal
expansion wire 177 contracts or an alternative motive means
subsides when current is removed.
[3470] In electrically operated radial projection units that use a
strip-spring to provide lift-shaft and tool-insert retractive
force, to avoid interference with the strip-spring by the thermal
expansion wire even when cool, the strip-spring is oriented
parallel to the coils in the expansion wire. As depicted in FIG.
57, on exiting through the opposite wall of the lift-shaft, the
thermal expansion wire or an electrical power line used to energize
elements internal to some or all of the tool-inserts can turn back
to the power supply or battery, or continue to the next unit or
another kind of electrical component. In piped units, as shown in
FIGS. 52b, 52c, 58, 59, 60, and 63, reversing the external pump or
switching the aesrosol canister or tank from one end of the line to
the other reverses which chamber is the ingress and which the
egress.
[3471] Centered within lift-shaft 182 and firmly secured to the
bottom of lift-platform 176 at both ends, tilting of lift-platform
176 by the pressure of fluid entering inflow (inlet, ingress)
chamber 194 with resultant jamming and leaking of the lift-platform
is prevented. Due to the downward urging of the strip-spring 187,
lift-platform 176 automatically descends when the upward force is
removed. Since the electrical current in nonpiped, or electrically
operated units, and the fluidic current (volume and pressure) in
piped, or fluidically operated units, can be varied, the extent and
duration of tool-insert elevation (projection) is jointly and
continuously variable. In nonpiped units, the spring or springs
pass between adjacent turns in a coiled thermal expansion wire.
[3472] In piped units, the pressurized liquid or gas flows past the
spring or springs, which made of a stainless steel or a polymer,
are little affected in restorative force by the temperatures and
chemical environment encountered. Both nonpiped and piped units can
be incorporated into minimally ablation or ablation and
angioplasty-capable barrel-assemblies. However, with either type
barrel-assembly engaged in the airgun, each projection unit
pipeline must communicate with an external pump, aerosol can, or
tank through a separate fluid coupling in a side-socket. The
primary benefit of minimally capable barrel-assemblies being lower
cost, multiply piped units requiring multi-port side-sockets are
incorporated into minimally capable barrel-assemblies only on an
exceptional basis.
[3473] VII2g(3)(d)(i). Structure of Radial Projection Units
[3474] An introductory description of electrically and fluidically
operated units is provided above in the section entitled Radial
Projection Units. For optimized functionality, the units in any
given barrel-assembly or separate (special, dedicated) radial
projection catheter, whether electrical or fluidic, are provided
with all of the connections and components essential to accommodate
any tool-insert of the type respective of each type circuit. More
comprehensively, while certain applications may justify varied
performance by differences in units rather than the tool-inserts
these accept, the projection units in any one circuit are usually
kept exactly alike.
[3475] Thus, even though an electrical/fluid system-neutral syringe
(emission tool-insert, emitter, injection tool-insert, injector,
ejection tool-insert, ejector) is self-contained and does not
require connection to an electrical or fluidic circuit, the socket
in the lift-platform at the bottom of the lift-shaft in either
system includes the necessary electrical contacts or fluidic
connections so that any other interchangeable tool-insert would be
supported.
[3476] Space available for each radial projection unit a function
of the diameter or gauge of the apparatus and the cross sectional
area available for each radial projection unit, both electrical and
fluidic circuits can be incorporated into the muzzle-head and/or
barrel-catheter of a single barrel-assembly or special radial
projection catheter. Smaller barrel-assemblies and special
catheters can generally accommodate a single electrical radial
projection circuit, a fluidic circuit requiring piping that demands
more space. Unit lifting mechanisms can be assembled within a can
or cup container which is then installed at the bottom of each
lift-shaft, or can be installed without such a container, as shown
in the figures.
[3477] VII2g(3)(d)(i)(1). Structure of Electrically Operated Radial
Projection Units
[3478] Referring now to FIGS. 52a, 53a, 54, 55, and 56, thermal
expansion wire 177 with elastic thermal insulation is wound no more
tightly in an oblate (flattened) helix (coil) as necessary and
passes along either long side of tool holding and lift-platform
shaft (lift-shaft, well) 182. Lift platform 176 and lift-shaft 182
are made of or lined with low friction material, typically a
fluoropolymer such as polytetrafluoroethylene. When to achieve
precise fit of lift-platform 176 in lift-shaft 182 as avoids
non-true radial travel and angling that results in jamming and tool
inefficiency demands greater cost, lift platform 176 is constrained
to level movement by prominences on the sides of lift-platform 176
that ride in channels in the walls of lift-shaft 182 as constitute
sliding ways.
[3479] When necessary, an open-topped tool-insert 184 such as those
depicted in FIGS. 53a, 53b, and 53c is prevented from being pulled
out of lift-shaft 182 when swept over the lumen surface by
overhanging or cantilevering swing-over hold-down arms 186 as shown
in FIGS. 54 thru 56, 59, 60, and 63. With injection and ejection
tool-inserts as shown in the foregoing figures, the end (terminus,
roof) of syringe barrel 196 intervenes between the top of syringe
plunger 197 and hold-down arms 186, serving as a stop limiting the
distance of projection or excursion within tool-insert 184 and the
outer surface of the muzzle-head or radial projection catheter.
[3480] To prevent the excursion or nonretraction of tool-insert
holding and lift platform 176 apart from thermal expansion wire 177
such as by dropping to the extended position under gravity, coiled
thermal expansion wire 177 is bonded to both the floor of
lift-shaft 182 and the underside of lift platform 176. To withstand
the temperature and deformation stresses involved, a silicone hot
melt adhesive can be used, such as Dow Corning.RTM. HM-2500
Assembly Sealant. Jamming during lift or descent due to tilting of
lift-platform 176 is prevented by making lift platform 176 and
lift-shaft 182 with a low friction polymer, such as nylon or
polytetrafluoroethylene.
[3481] Less slippery materials can be used when lift-platform 176
is additionally surrounded with a hemispherical standoff guard rail
where lift-platform 176 is in contact with lift-shaft 182 (not
shown). The alternative use of vertical bosses is addressed below
in this section. Still referring to FIG. 53a, to preclude the
levering forces encountered when the working tip of tool-insert 184
is applied to the lumen wall from pulling tool-insert 184 out of
holding and lift-platform 176 or holding and lift platform 176 out
of lift-shaft 182, tool-insert 184 must be securely engaged within
receptacle-type lift-platform lift-platform 176 by spring-pin,
screw-in, or friction fit, and lift-platform 176 prevented from
being extracted from lift-shaft 182 by friction fit.
[3482] Tool-insert holding and lift platform 176 is in turn
prevented from being pulled out by rotatable or swing-out retaining
(hold-down, lock-down) arms 186 in FIGS. 52a, 52b, 54 thru 56, 59,
60, and 63, which rotate or slide over the upper edges of
tool-insert 184 at the sides of lift-shaft or well 182 at the outer
surface of the muzzle-head or radial projection catheter. Permanent
and fixed, the fluid ejector, irrigator, and aspirator unit shown
in FIG. 53c does not require hold-down arms and does not constitute
a radial projection unit able to accommodate different
tool-inserts. The depth of inset on the tool-insert and surface of
the muzzle-head or dedicated catheter are equal, so that when
tool-insert 184 is inserted into lift-shaft 182, the upper or
radial surfaces of these are level.
[3483] Restrained by the floor beneath and the walls of lift-shaft
182 at the sides, coiled thermal expansion wire 177 is constrained
to expand upwards, raising lift-platform 176. Heat generated by
expansion wire 177 should be prevented from spreading beyond
lift-shaft 182, and cold used for cryotherapy, cryoplasty, or to
extend adhesive open time, for example, should be prevented from
cooling expansion wire 177. If the muzzle-head polymer, usually a
fluoropolymer (polytetrafluoroethyl-ene) does not intrinsically
impart sufficient insulation to lift-shaft 182, then the internal
surfaces of the muzzle-head aside from the heat-window or windows
are coated with thermal insulation, such as squares of
polytetrafluoroethylene impregnated thin glass fabric glued to the
internal surface with high temperature silicone adhesive.
[3484] A piped lift-shaft may also require insulation from heat
generated by the turret-motor and recovery electromagnet windings,
especially when these are used as heating elements. The application
of current to thermal expansion wire 177 overcomes the downward
urging force exerted by strip-spring 187 causing insert-tool
holding and lift-platform 176 to rise, extending the working face
of tool-insert 184 beyond the periphery of the muzzle-head or
radial projection catheter. The barrel-assembly can be rotated
manually or with the turret-motor, and/or reciprocated manually or
with the linear stage to exert a shaving or abrading action against
the lumen wall.
[3485] Either or both the turret and linear stage motors can be
used to impart oscillatory motion to the tool-inserts; however, the
linear stage motor then must be closed loop controlled. The
oscillatory mode of the turret-motor, as addressed above in the
section entitled Turret-Motor Operational Modes, can be used to
oscillate the muzzle-head at right angles to the cutting edges of a
cutting tool, for example. The tool-inserts if left extended when
unintended could injure the lumen wall. This is averted by virtue
of the constant urging of strip-spring 187, which causes the radial
projection units to automaticallyi descend when not deliberately
energized, eliminates the need for motion sensors and a control
circuit to accomplish the same action.
[3486] In an nonpiped, that is, an electrically operated
embodiment, the speed of retraction (lowering, withdrawal, descent)
of lift-platform 176 is contingent upon the rate of cooling, hence,
contraction (recession) of thermal expansion wire 177, whose
lifting force of restraint against the downward urging of
strip-spring 187 on lift-platform 176 strip-spring 187 cannot
counteract unaided. If necessary, retraction can be accelerated by
insertion of a cooling catheter or catheters though the barrel-tube
closest to the unit or units. Continued elevation of lift-platform
176 is essential to allow a cutting or abrading tool-insert, for
example, to continue in use.
[3487] The materials used of low thermal conductivity and with
thermal insulation applied when necessary, exchanges in temperature
between thermal expansion wire 177 and its surroundings are slight,
and only extreme and protracted cold would be expected to cause
thermal expansion wire 177 to contract allowing the lowering of
tool-insert 184 while conducting current intended to maintain it in
use. Contraction due to environmental cold must be considered 1.
During the continued use of tool-insert 184, where tool-insert 184
must be kept in the extended position (projected, elevated) so long
as current is sent through thermal expansion wire 177, and 2. As
insufficient to assist in the prompt contraction of thermal
expansion wire 177 once current has been cut off so that
tool-insert 184 will retract.
[3488] Any insulation used to isolate thermal expansion wire 177
from the chilling surroundings during a cryoplasty, for example,
will at the same time result in the need for colder or more
extended chilling, such as by a cooling catheter, in order to
accelerate withdrawal of the tool-insert once current is removed.
Thus, quick retraction through the insertion of a cooling catheter
limits the thermal insulation that can be used, but this factor
must be weighed against the cold to which the wire is to be exposed
with the tool-insert kept in use. Increasing the current to thermal
expansion wire 177 in order to overcome the counteracting effect of
surrounding cold is limited by the ampacity (current tolerance) of
thermal expansion wire 177, which latter must remain relatively
thin due to the dimensions of the radial projection unit
overall.
[3489] Whether and to what extent thermal expansion wire 177
requires thermal insulation depends upon whether it is meant to
allow a tool-insert to continue in use without retracting while the
treatment area is chilled, as occurs when the a piped unit is used
to supply cold gas during cryoplasty, for example, and the cold
compensating increase in current that thermal expansion wire 177
can support without melting. When near to a piped unit or units or
to a barrel-tube which is used to deliver chilling gas or liquid to
the treatment site, thermal insulation may be necessary to
counteract the heating environment and preserve independent
operation so that inappropriate lowering of lift-platform 176 does
not occur so long as the maximum allowable actuating current
continues.
[3490] Any significant chilling of thermal expansion wire 177 will
be dependent upon the specific configuration and dimensions of the
unit elements, their proximity to the source of chilling, the
thickness and thermal conductivity of the intervening materials,
and the degree and duration in difference in temperatures between
thermal expansion wire 177 and the chilling fluid. When necessary,
thermal expansion wire 177 is insulated with elastic thermal
insulation having a coefficient of linear thermal expansion
determined according to American Society for Testing and Materials
Standard D3386-94 Standard Test Method for Coefficient of Linear
Thermal Expansion of Electrical Insulating Materials.
[3491] Accordingly, any insulation of thermal expansion wire 177
must be specific to the capabilities of the barrel-assembly, many
of which will not be used for a cryoplasty, for example. Tool
holding and lift-platform shaft 182 is flat and smooth walled, both
it and the outer sides of lift-platform 176 made of low friction
low heat conducting polymer, lift-shaft 182 normally machined into
or lined with polytetrafluoroethylene as are contacting surfaces of
lift-platform 176.
[3492] Referring to the view of FIG. 53a, were lift and descent not
level without greater vertical constraint to prevent jamming,
lift-platform 176 and lift-shaft 182 would be provided with
leveling guides or slideway channels s in the form of vertically
extended protrusive ways or bosses at the sides of lift-platform
176 with complementary receiving channels on the proximal and
distal or inner sides of lift-shaft 182 that support all sliding
contact at their interface. Such vertically oriented ways or
channels are the same in vertical extent as the vertical distance
moved by lift-platform 176. Lift-shaft 182 has hold-down arms 186
to prevent lift-platform 176 from being pulled out of lift-shaft
182 by the levering forces encountered by side-cutting or abrading
tool-inserts. Specifically, lift-platform 176 is prevented from
upward movement beyond the rim of lift-shaft 182 by swing-over
hold-down arms or clamps 186.
[3493] To preserve the continuity of the muzzle-head,
barrel-catheter, or radial projection catheter surface, swing-over
hold-down arms 186 are inset within depressions at points about the
perimeter, such as along the proximal and distal sides of
lift-shaft 182 rim. Swing-over hold-down arms 186 are fastened at
their outer ends to rotate into position over the tops and into
complementary depressions in the upper surface of tool-insert 184,
thus acting as swing over lock-down arms 186. A single hold-down
arm 186 with the fastener similarly acting as the rotary joint at
its center rather than toward one end, can secure adjacent
tool-inserts. Such hold-down arms 186 are suitable only where
tool-inserts are inserted in the adjacent lift-shafts, although a
dummy tool-insert can be used to preserve continuity at the
surface.
[3494] Half semicircular depressions in the upper edges of
lift-platform 176 receive the swing-out arms in flush relation.
Tool-insert holding and lift-platform 176 in FIG. 53a frames about
the receptacle used for receiving interchangeable tool-inserts
friction fitting into it such as those shown in FIGS. 53b and
53c.
[3495] The underside of holding and lift-platform 176, usually made
of or veneered with polytetrafluoroethylene, is fastened to the
thermal insulation enclosing thermal expansion wire 177, which in
turn is fastened to the floor of lift-shaft 182 assuring descent
with the contraction upon cooling of thermal expansion wire 177.
While the radial projection units are shown with shafts and
tool-inserts that are hexahedral or rectangular in vertical cross
section, these could just as well have been circular or elliptical,
for example.
[3496] To prevent lift-platform 176 from being pulled out of
lift-shaft 182 by levering and expulsive forces encountered during
tool-insert use and to allow the use in fluidic circuits of inert
bits and syringes that block the outflow of fluid and allow the
fluid to continue through the circuit as well as to avoid sharp
projecting edges at the outer or radial surfaces of the muzzle-head
or radial projection catheter, tool-insert holding and
lift-platform 176 and tool-insert holding and lift-platform 176
have depressed areas for allowing slide- or swing-over hold-down
arms 186 to be positioned over the outer or radial surface of
tool-insert holding and lift-platform 176 in inset relation to the
radial surface.
[3497] When present, these are positioned over the tops of side
boss guides and channels. While not ordinarily needed with friction
fit tool-inserts 184, hold-down arms 186 can be extended over the
radial edges of these for increased retention. The depth of the
depressed areas is the same as the vertical thickness of swing or
slid out arms 186, so that the elsewhere the upper surface of
lift-platform is level with the rim of lift-shaft 182 at the outer
surface of the muzzle-head or radial projection catheter.
[3498] VII2g(3)(d)(i)(2). Structure of Fluidically and
Microfluidically Operated Radial Projection Units
[3499] As with electrically operated units, space optimization
requires that every unit have maximum potential functionality to
support any suitable tool-insert. Nevertheless, a unit of given
specification will be able to accommodate fluids of different
viscosity moved at different velocities only over a limited range.
Thus, while units for use with non flow-through inert bits and
syringes could be provided with a lift-platform that had no path
for fluid to flow through, such gratuitous limitation is not
preferred. Providing all fluid units with a lift platform that
includes a hinged perforated cover over the outlet chamber and
chamber partition that affords a passageway allows tool-inserts to
be used for aspiration.
[3500] Liquids are generally superior for aspiration due to the
momentum imparted to the debris, which is wetted and swept away
with a washing effect. Propelling the debris through the line and
components with greater force forestalls clogging and therewith the
need to halt the procedure in order to flush the line with sodium
hypochlorite, for example. Similar economies apply to fluidic
tool-inserts, so that, for example, an initial dose or front-loaded
fluid ejector is used as a noninitial dose intermittent or
continuous fluid ejector and as an irrigator. Aspiration is
addressed in the section above entitled Radial Projection Units and
the section below entitled Use of Flow-reversible Tool-inserts for
Microaspiration.
[3501] Both open and closed circuits can be adapted for
miniaturization and incorporation into ablation or ablation and
angioplasty-capable barrel-assemblies and radial projection
catheters. Closed circuits are preferred for quicker response times
and greater pressure range under potentionally exigent
circumstances. In a closed circuit, flow is past rather than
directly to and from each unit tool-insert holding and
lift-platform, necessitating the incorporation of a lifting
mechanism adapted to alternately actuate during a passing antegrade
flow and aspirate during a passing retrograde flow as often as
desired. Radial projection units with hinged lifting chamber
perforated passive fluid resistor roof-plates as described below
thus pertain to tool-inserts capable of aspiration in a
closed-circuit.
[3502] Referring now to FIG. 61, shown is a detail of the lifting
mechanism of a fluid radial projection unit. To prevent the passive
dropping away of lift-platform 176 under gravity when not lifted by
the force of passing fluid and to achieve quick and positive return
and seating of lift-platform 176 upon the cessation of flow,
strip-spring 187 is used to elastically retract lift-platform 176
into flush relation with the top of fluid chamber separator 188. In
antegrade operation, fluid enters and fills antegrade inflow or
inlet chamber (entry chamber, ingress chamber) 194, pushes up
against the underside of lift-platform 176 and upon exceeding the
restraining force of strip-spring 187, forces lift-platform 176 to
rise (radially outward).
[3503] The fluid-tight fit of lift-shaft 182 by tool-insert 184
prevents lift-platform 176 from being tilted upwards on the
proximal inlet driven side, and to preclude jamming, the surfaces
of lift-platform 176 and lift-shaft 182 that come into contact are
made of or coated with a fluoropolymer or other slippery resin. For
this reason, testing for operability and leaks prior to use must
always be with a tool-insert installed in every unit. For testing
in manufacture, inert blanks can be used; however, testing prior to
a procedure should always be with the tool-inserts actually to be
used regardless of type. Strip-spring 187 is fastened at its center
to the top portion 189 of fluid chamber separator 188 by flat head
pin, screw, or rivet 198.
[3504] For more secure attachment to the top of chamber separator
188, when upper portion 189 of chamber partition 188 is molded,
pin, screw, or rivet 198 provided with a flange toward its embedded
or distal end is inserted into the mold before injection. If
necessary to avoid affecting the restorative force of strip-spring
187 by including it in a mold that includes pin or rivet 198 under
high temperature, strip-spring 187 is fastened to the top of
chamber partition (separator, divider, barrier) 188 through a hole
at its center and the upper end of pin or rivet 198 flattened over
it to create a head. If flattening by hammering or pressing would
damage separator 188, then rivet 198 is extended to the bottom
thereof so that rivet 198 rather than separator 188 sustains the
force applied to flatten the head.
[3505] Strip-spring 187 has small slots toward either end so that
the fasteners used to secure it to the underside of tool holding
and lift-platform 176 can slide therein when lift-platform 176
moves up and down. Proper function requires that fluid from the
supply line be properly apportioned between that forced up through
the tool-insert and that continuing forward through the circuit.
Fluid operated tool-inserts may have an actual cylindrical plug for
insertion in the receptacle or socket atop the lift-platform or may
provide only an opening that requires the lift-platform receptacle
to supply the surrounding wall as a virtual plug.
[3506] The interposition of a fluid resistor in the path across the
entry orifice (inlet, mouth) of the space for a fluid tool-insert
inlet portal 201 through base entry and discharge portal or
passageway 220 space or receptacle prevents fluid rushing past the
orifice at a high rate from creating an unintentional vacuum at an
ejection or injection tool-insert working face. Perforated plastic
outlet chamber roof-plate 199 is therefore placed in the path of
the fluid as a fluid resistor or flow resisting gate, referred to
as roof-plate 199, with notch to clear strip-spring 187 and
strip-spring securing pin, screw, or rivet 198 over outlet chamber
195. Roof-plate 199 is hinged along its upper distal edge by
thinning short of its attachment to the chamber edge.
[3507] To limit the angle to which roof-plate 199 can rise so that
fluids over a certain range are best accommodated, roof-plate 199
hinge 200 can include a stop. Differential response among
tool-inserts best built into the tool-inserts rather than the
lifting units, which should be uniform. If desired, however,
differential resistance to lifting of the perforated passive fluid
resistor roof-plate 199 during aspirative or retrograde flow can be
obtained by varying the resistance to the lifting flow posed by
each roof-hinge, whether by making the roof-plates of different
materials or varying hinge thickness, the size range not permitting
the use of separate torsion springs.
[3508] The extent of roof-plate 199 rising and size of its
perforations are determined by the viscosity and velocity of the
fluid or fluids employed during antegrade flow to actuate and
retrograde flow to aspirate. An additional factor during aspiration
is the anticipated size of the debris particules to be swept away.
This can to a significant extent be controlled through the choice
of inert bit or working face used to free the debris. When
lift-platform has mounted thereupon a flow-through tool-insert
rather than an inert bit blank, raising lift-platform 176 exposes
tool-insert base-plug space entry orifice or receptacle opening 201
so that fluid can rise up into tool-insert 184.
[3509] Once lift-platform 176 is raised, fluid spills over the top
of chamber partition 188, encounters fluid resistor 199 which
raises the fluid pressure for lift-platform 176 to be driven higher
forcing fluid up through base-plug space or receptacle opening 201.
The composition of the fluid and velocity through the line
determine the flow-through rate of roof-plate fluid resistor 199.
Outlet (outflow, egress) chamber 195 fluid resistor roof-plate 199
has spanning from side to side along its underside near chamber
partition 188 small roof-plate force-down blade 202 with bottom
edge inclined toward chamber partition 188 that serves as a 2-way
class II lever to assist in forcing roof-plate 199 down during
antegrade flow (from left to right in FIGS. 59, 60, and 63) and up
during retrograde flow.
[3510] It will now be apparent that during retrograde flow in
aspiration, perforated passive roof-plate fluid resistor 199 also
serves to increase the velocity of flow past opening or inlet 201
leading up into base-plug space, thus creating a pressure drop that
results in an intake or aspirating force through any opening in the
tool-insert working face. Fluid that is not diverted up through
base-plug opening 201 flows through roof-plate fluid resistor 199
into outlet (ouflow, egress) chamber 195, thence down the line to
the next ingress chamber, where the process is repeated.
Lift-platform 176 is shown as having been raised by the surge of
fluid over chamber divider (barrier, separator) 188.
[3511] Both nonpiped and piped pipelines function bidirectionally,
and as depicted in FIGS. 57 and 58, in either, units can be
arranged along a complete circuit or represent a singular, hence,
independently controllable, end-unit, and various circuit elements
might be introduced into the circuit to affect the units past that
point. In barrel-assemblies and dedicated radial projection
catheters used with fluids that cover a small range in viscosity,
perforated plastic roof-plate fluid resistor 199 is permanently
fastened along the upper edge of outlet or distal chamber 195
outlet, that is, atop the distal wall, by means of a flexible cloth
tape hinge bonded by means of a suitable adhesive so that during
antegrade flow, roof-plate 199 closes over the top of outlet
chamber 195.
[3512] When the barrel-assembly or radial projection catheter must
be usable with fluids covering a wide range in viscosity, outlet
chamber roof-plate 199 is made interchangeable with plates of
different pass-through conductance or permeability. Hinged
attachment can be accomplished by means of watch band pring pin
type fastening, which allows plates of different resistance to be
interchanged by means of a tweezers or hemostat, for example.
Reversing the direction of flow when the pump is reversed to
initiate aspiration causes roof-plate 199, which would otherwise
become clogged with aspirated debris, to lift up out of the path of
the pumpward bound fluid.
[3513] When following aspiration this gate is in the lifted
position, reversing the flow back into the forward direction will
cause fluid to press against roof-plate force-down blade 202,
levering roof-plate 199 back down into flush relation against the
top of outlet chamber 195. During retrograde flow, the rush of
fluid past base-plug entry orifice 201 imparts the vacuum effect
desired at the working face of tool-insert 184. Accordingly, the
roof of outlet chamber 195 is made of perforated plastic sheeting
having a thickness, cross sectional area, and number of
perforations responsive to the viscosity or range thereof. If
always used with the same viscous fluid, the barrel-assembly or
dedicated radial projection catheter is marked as intended for use
in this viscosity range.
[3514] Preferably, the plastic plate, which to defer becoming
clogged by debris during aspiration long enough to complete the
procedure must be hinged to open, can be snapped in or out allowing
the plate to be changed for use over a certain viscosity range.
Both elastomeric membrane valves and strip-springs are spring
valves. Both can be used to adjust tool-insert lifting force and
control the rate of flow-through at a given line pressure. The
specification herein of strip-springs is not to be interpreted in a
limiting sense as to omit the use of equivalent elements, such as
elastomeric membrane slit valves, for example.
[3515] Broadly, elastomeric membrane slit valves function
bidirectionally, afford an area from central to peripheral for
fixing the entry, and covering over an area independently of slit
size or conformation, are suited for valving wide openings, whereas
strip-springs function unidirectionally, are usually narrow, and
are able to provide mechanical restorative force for returning the
moving part loaded to its spring resting or starting position.
Fluid at the minimum threshold pressure thus forces itself past the
strip-spring up to its flexible limit. When the platform contains a
hole and the fluid has no alternative path, a pressure head of
sufficient force opens the joint allowing fluid to flow through the
hole.
[3516] The strip-spring acts as a fluid valve or regulator which
maintains a consistent relation of direct proportionality between
the imposed pressure, extent of joint separation, and in a fluid
circuit, rate of flow, which it does as the passive consequence of
its intrinsic restorative force. As the pressure subsides until its
force decreases below the threshold, the strip-spring pulls the
platform back into closed flush relation with itself passively,
proportionally and automatically. In a piped unit of the kind shown
in FIGS. 59, 60, and 63, inflow-outflow chamber partition 188
serves not only to secure strip-spring 187 at the center,
automatically retracting lift-platform 176 when the fluid current
hence lifting force is removed, but to direct fluid entering
through antegrade (left to right as shown) inlet line 203 against
the underside of tool-insert 184, forcing the fluid over chamber
partition 188.
[3517] When the base consists of a lift-platform that can be pushed
up into a slightly wider upper body portion, as is essential in a
continuous or non syringe injector, this lift-platform 176 is
raised. A passive ejection tool-insert need not be lifted up
against the lumen wall as must an injector or working face. Such a
tool-insert has a unitary body. Fluid is thus driven up through the
tool-insert and out the radial working face of the tool-insert.
When the direction of flow is reversed in aspiration, outlet
chamber roof-plate fluid resistor 199 is no differently raised by
the inrush of fluid as in antegrade flow, and lift-platform 176 is
lifted against the restraining force of strip-spring 187.
[3518] Hence, retrograde flow during aspiration does not
significantly affect the lifting of lift-platform 176. Strip-spring
187 crosses over only the central portion the lower entry into
base-plug 201 as shown, so that fluid pushes up against the bottom
of lift-platform 176 to either side of strip-spring 187.
Strip-springs used in fluid tool-inserts as a secondary resistance
to injector lifting or to restrict a gap and thus the flow-through
rate of an ejector used to deliver a low viscosity fluid, for
example, can be given any conformation necessary. A loss in
restorative force due to the need for cutouts, for example, is
compensated for through the use of stiffer, plied, or thicker
stock.
[3519] VII2g(3)(d)(i)(3). Extended Projection Scissors
Lift-Platform Mechanism
[3520] In an electrically or a fluidically operated or nonpiped
unit of adequate size, the distance of radial projection can be
increased by incorporating a class I lever disposed in parallel
relation to the floor of the lift-shaft to pull at the bottom end
side-to-side cross beam of a stainless steel or tough
surfactant-free polymer scissors lift thus causing the scissors
lift to extend the tool-insert holding and lift-platform up from
the floor of the lift-shaft. The use of a polymer is preferred as
having a lower thermal coefficient. The lift is a microminiature
version of a conventional workman's lift platform, the distance of
lift dependent upon the length and number of scissors pivot arms.
In an electrical unit, the scissors lift replaces the thermal
expansion wire.
[3521] So that the lift will resist lateral deflection when the
tool-insert it supports is in use, the pivot joints must be tight
or free of play and rotate with minimal friction, and the rotary
joints connecting the arms of the lever must resist vertical
movement. The links of the scissors lift limit its descent to less
than horizontal as would prevent a sidewise pulling force from
causing the lift to rise. In a fluidically operated unit, the flow
rate of fluid delivery must be adjusted apart from its adjunct use
to raise the lift-platform to a height proportional to the
instantaneous current or rate volume of fluid of flow-through. The
lever is fulcrumed about a rotary joint or axle pivot by the
anchoring or embedment of its lower end into the floor of the
lift-shaft, an expanded head preventing the lever from upwards
disengagement.
[3522] The shorter or effort arm of the lever is connected to a
direct current spring-return intermittent duty push or punch type
solenoid and longer or resistance arm connected to the scissors
lift bottom side-to-side cross bar by a link having rotary joints
at both ends. The scissors lift bottom side-to-side cross bar
closer to the solenoid is unconnected to either the solenoid or the
lever and free only to rotate about an axle securing it to a side
rail. The bottom side-to-side cross bar of the scissors lift
opposite from the solenoid is free to move but is constrained by
short low friction cylindrical extensions or studs at either side
that pass through and ride along slots in the side rail to either
side, expanded heads at the extremities thereof constraining the
motion of the lift platform.
[3523] So that the lift platform will be stable when raised and a
tool-insert in use, all joints and ways must be free of play and
low in friction. The lever reduces the stroke or throw required
which allows the of a solenoid as an actuator of acceptable service
life. The scissors lift extends the lift platform farther outward
radially and beyond the outer surface of the muzzle-head. It thus
precludes the use of hole-down or lock down arms 186 in the
figures, dependent for stability in use instead upon secure
anchoring into the floor of the lift-shaft and the rigidity of its
joints.
[3524] Extension past the outer surface of the muzzle-head opens
the lift-shaft to the entry of debris all around that would foul
the scissors lift preventing it from retracting and seating
properly. The lift-platform is therefore aproned entirely around
with a thin and soft but strong polymer velum or film, such as of
low density polyethylene or polypropylene. The apron is bonded at a
slight distance from the periphery to the underside of the
lift-platform. The upper edge of the lift-platform is routed to
provide a recessed ledge all around into which the apron folds when
the lift-platform is lowered.
[3525] VII2g(3)(e). Radial Projection Unit Tool-Inserts
[3526] Fluidically operated or piped tool-inserts draw fluid from
or return fluid to the fluid control circuit on a continuous or
intermittent basis, to which these therefore require direct
connection. Delivery of fluid from the fluid circuit means that the
fluid used for control and that to serve as a therapeutic agent are
one and the same, with fluid in the line replenished by take-up
from a reservoir. In an ablation or ablation and
angioplasty-capable barrel-assembly, the fluid circuit to include
reservoir can be built into the battery pack handgrip section.
These are usable only in fluid units in a fluid circuit. By
contrast, mechanical syringes are self-contained and enclose a
finite amount of injectant or ejectant.
[3527] Neither these nor inert bits such as shavers and brushes
require direct connection to the lift-platform control current.
While the muzzle-head is endoluminal, individual tool-inserts
cannot be changed. However, selecting tool-inserts with different
electrical or fluid actuating current levels allows individual
tool-inserts in the same circuit to be differentially and/or
sequentially actuated, tool-inserts can belong to different
circuits, fluid emitter-irrigator-aspirators can be changed in
function or the fluid through a given circuit changed at the
reservoir, and bipartite or duplex barrel-assemblies can be
resheathed with alternative combination-form radial projection
catheters as the peripheral component without the need to withdraw
the ballistic component of the barrel-assembly.
[3528] Equally usable in either electrical or fluidic units,
mechanical syringes and bits are referred to as electrical/fluid
system-neutral. The same mechanical injector or injection
tool-insert shown inserted into an electrical projection unit in
FIG. 54 is thus shown inserted in a fluidically operated unit in
FIG. 59. A tool-insert which incorporates an electrically operated
feature such as a heating coil that must be controllable
independently of the thermal expansion wire requires connection to
a separate electrical circuit. Electrical tool-inserts are
therefore usable on in radial projection units that provide a
source of electrical current other than that used to operate the
lifting mechanism.
[3529] This can be provided in fluidically operated units; however,
when an electrical function is desired, control is made simpler if
a unit in a parallel electrical circuit is used. A tool-insert,
such as a shaver or brush, which incorporates a fluidically
operated feature such as jet irrigation is usable only in a fluid
circuit. Fluid injectors and ejectors sold with an initial dose of
medication or another therapeutic substance combine characteristics
of mechanical syringes and fluid tool-inserts, most made for one
time use and disposal. Electrical or nonpiped radial projection
unit tool-inserts are either blanks that are flat-faced for use as
pushing arms or caps to seal off piped outlets or nodes, or
ablative tools that are equipped with microrazors; bristle
projections, or diamond particles for abrading tissue from the
lumen wall.
[3530] Cutting tool-inserts can be manually swept over the plaque,
with or without the turret-motor oscillatory mode used to vibrate
the working end of the tool against the lesion. One or several
tool-inserts can be provided. Piped radial projection unit
tool-inserts can be perforated for delivering or aspirating a fluid
or include multiple hypotubes to allow hypointimal,
hypoendothelial, or intramural injection. Piped radial projection
units are addressed below in the section entitled Piped Radial
Projection Unit Tool-inserts. Provided a diamond tipped tool
generates debris of a size small too small to embolize, an
electrical unit can be used; otherwise, a trap-filter and
preferably fluidic unit with aspiration are used.
[3531] Different tool-inserts are used for brush cytology, removing
uncalcified plaque by cutting or abrasion, to push the muzzle-head
towards the opposite direction, inject medication into the lumen
wall, chill or heat the lumen wall, and so on. While medication
should make further means for countering platelet aggregation
nonessential, using a piped radial projection unit, a gas or liquid
coolant such as chilled water, saline solution, nitrous oxide, or
freon, can be moved across the inner face of the cutting head to
reduce any conduction of heat. The passing of the tool over the
lumen surface may be referred to as `side-sweeping` regardless of
whether a brush type tool-insert is used. Brush-type radial
projection unit tool-inserts can be made to cover a wide range of
bristle tip configurations, so that the specific appearance of the
brushes in a given barrel-assembly as shown must be taken as
exemplary.
[3532] The radial projection units can contain one or more brushes
of like or different kinds, the face dimensions contingent upon the
openings in the lift-platforms into which these must be engaged. To
aid observation, radial projection unit tool-inserts are marked
with bright contrast. A closed-face or blank tool-insert is used to
fill the lift platform opening when another tool-insert is not in
use. A blank can be used to push or nudge the muzzle-head toward
the opposite direction to increase the force applied to a shaving
tool-insert on the opposite side, for example. A blank tool-insert
in a piped unit, as addressed below in the section of like title,
can serve as a heating or cold plate when hot or cold fluid is
flowed over the inner face.
[3533] The temperature can be adjusted from the cryoplastic to the
thermoplastic with temperature reversal and stabilization at any
intervening point as needed. Radial projection unit tool-inserts
for ablative or atherectomy application are brush-like in
conformation, the shaft stiffness and bristle tips configured to
provide selectable gradations in the aggressiveness of tissue
swabbing (swiping) or removal. When inserted into the tool holding
lift-platform in a radial projection unit having a rear supply and
aspiration line, either type of tool-insert can be perforated to
allow materials to pass to or from the lumen wall. In an artery,
the ability to brush the lumen wall makes it possible to accomplish
a percutaneous translumininal atherectomy and remove, rather than
smash plaque up against the lumen wall, as does a balloon
angioplasty.
[3534] An injection tool-insert such as shown in FIGS. 54 and 59
allows the introduction of a swelling or hardening (sclerosing)
agent or medication preparatory to or following implantation. Brush
tools with projections or bristles that unfold to greater length or
that are biased to resist movement in one direction and fold in the
opposite direction where different projections on adjacent tools
could perform one action one way and another in the reverse
direction are possible. Gradual retraction of the lift is passive,
by the restorative force of the strip-spring upon the removal of
current, and quick retraction active, by inserting a cooling
catheter as addressed above in the section entitled Cooling
Catheters (Temperature-changing Catheters).
[3535] Prone to the same complications as is every other means of
intervention, the procedure can 1. Generate potentially embolizing
debris, recommending the deployment of a run-ahead trap-filter, as
addressed below in the section entitled Embolic Trap Filter in
Radial Discharge Muzzle-heads for Use in the Vascular Tree, 2.
Induce abrupt closure, recommending the administration of
antithrombogenic and antispasmodic medication, as addressed above
in the sections entitled Risk of Abrupt Closure and Stent- and
Shield-jacket Moisture barrier-coated viscoelastic polyurethane
foam Linings, and 3. Prompt intimal hyperplasia, recommending the
administration of antirestenotic medication such as paclitaxel,
rapamycin (sirolimus), and/or radiation, and immediate
stenting.
[3536] Nonbristled inserts in the lift wells allow the muzzle-head
to be nudged to a side of the lumen, clearing more cross-sectional
area for contents to pass. In a blood vessel, minimizing occlusion
time during an angioplasty has been demonstrated to lead to better
results (Iliodromitis, E. K., Paraskevaidis, I. A., Fountoulaki,
K., Farmakis, D., Andreadou, I., Antoniadis, A., Ikonomidis, I.,
Leftheriotis, D., and Kremastinos, D. T. 2008. "Staccato
Reperfusion Prevents Reperfusion Injury in Patients Undergoing
Coronary Angioplasty: A 1-Year Follow-up Pilot Study,"
Atherosclerosis 204(2):497-502). Hard mineral deposits can be
removed during any procedure performed with a combination-form
barrel-assembly, as addressed below in the section entitled
Barrel-assembly with Exchangeable or Built in Rotational
Atherectomy Burr.
[3537] Avoiding withdrawal and reentry reduces irritation at the
entry wound but more particularly, allows the muzzle-port to remain
in position over the sampled area for discharge. To allow the
entire procedure to be performed without the need to withdraw and
reenter, a combination-form barrel-assembly, as addressed below in
the section entitled Through-bore, or Combination-form,
Barrel-assemblies: Barrel-assemblies which Accommodate or
Incorporate Means for Ablation, Thrombectomy, Atherectomy,
Atherotomy, and/or Endoscopy with either apparatus inserted is
used. Such a barrel-assembly has a continuous central canal that
opens at the muzzle-head nose that can be used as a kind of
guide-catheter.
[3538] Except when hard mineral deposits such as calcified plaque
in an artery must be removed, a noncombination-form ablation or
ablation and angioplasty-capable barrel-assembly can be used. Using
inmate radial projection units, the toughness of the material that
may be abraded away or ablated depends upon the 1. Stiffness of the
shafts and tip configuration of the individual projections
(bristles, aristae, setulae, pectinatae) of the tool-inserts, such
as those shown in FIGS. 51Ba and 51Bb, which function in a cutting
manner similar to a conventional atherectomy catheter; 2. Output
torque of the turret-motor on rotation; 3. Whether the turret-motor
is used in oscillatory mode; and 4. Pushing and pulling force
exerted by the operator or linear stage during transluminal
displacement.
[3539] Due to differing tissue destructive action exposure times,
the different ablative means incorporated into the muzzle-head are
rarely if ever to be used simultaneously to perform an ablation or
to eradicate liberated debris. More specifically, thermal ablation
or atherectomy using recovery electromagnet heat-windows, or
cryogenic ablation or atherectomy through connection to a source of
cryogenic fluid, is not combined with abrasive side-brushing or
shaving by tool-inserts. However, for use in ablation or ablation
and angioplasty-capable barrel-assemblies, the potential utility
for consecutive use of these processes justifies incorporating
brushing, aspirating, and medication-delivering side-sweepers and
heat-windows in muzzle-heads.
[3540] The speed and vigor of sweeping are increased through use of
the vibratory, or oscillatory, mode of the turret-motor, as
addressed in the section above entitled Turret-motor Operational
Modes and that below entitled Modes of Failure. Use of the
oscillatory mode generates a larger amount of debris in a given
interval, recommending use with insert brushes that incorporate an
aspirant evacuation path for use in a fluid-controlled line which
can be reversed in the direction of flow to provide aspiration,
such as those shown with injection tool-inserts in FIGS. 54 and 59.
Except in a barrel-assembly marked `Not to Be Used in Blood
Vessels,` which will lack a run-ahead trap-filter, the current to
abrading or brush type tool-inserts is shunted through a time delay
relay, causing the radial projection unit to lift the tool into
position or to deploy a moment after the trap-filter, which
receives current directly.
[3541] In the gut or airway, provided the patient is recumbent, a
dropped miniball sticks to the side of the lumen and is readily
retrieved, making the use of a trap-filter unnecessary. Biopsy
sample aspiration with or without the aid of brush or aspiration
tool-inserts can be accomplished without the need for withdrawal
and reentry in order to initiate the discharge of medication and/or
stent miniballs. Withdrawal is avoided by aspirating the material,
whether loosened with the aid of an abrading or shaving
tool-insert, from the lumen surface through a service-catheter, as
addressed in the sections below entitled Service-channel Adhesive
Delivery Line and Muzzle-head Access by Means of a
Service-channel.
[3542] Use of a barrel-assembly for aspiration is also addressed
above in the section entitled Use of the Barrel-assembly as an
Aspirator or Transluminal Extraction Catheter to Retrieve Biopsy
Samples. The sample need be aspirated out through the inserted
catheter only far enough to allow its recovery on withdrawal. While
for most purposes, a barrel-tube that is not required for discharge
can serve as a service-catheter rather than as the service-channel
or conduit for a narrower service-catheter, this is not true when
tissue must be recovered for analysis and not just removed by means
of aspiration. This is because the vacuum pressure required to
withdraw the sample, which will usually cling to the inside of the
catheter, the entire distance to the proximal end will cause injury
to if not perforate the treatment site.
[3543] Aspiration is ordinarily by bulb or syringe pipetting the
sample into the distal end of the service-catheter with the least
vacuum that will allow a viable sample to be retrieved. The
catheter is then withdrawn and the sample blown onto a slide or
into a pertri or other sample dish, test tube, or crucible.
Microtome-like tissue samples are obtained by inserting a shaving
or razor head into a radial projection unit and drawing the shaving
into the distal end of a service-catheter. To minimize damage to
finely sliced samples, clinging to the inside walls of the
service-catheter is made of polytetrafluoroethylene. A side-socket,
as addressed below in the section entitled Ablation or Ablation and
Angioplasty-capable Barrel-assembly Side-socket, for admitting the
service-catheter into a barrel-tube, allows the barrel-assembly to
remain engaged within the airgun without the need to move the
muzzle-head.
[3544] This allows maintaining a steady position so that discharge
is not redirected away from the same small target area just treated
or sampled. By contrast, a barrel-assembly without a side-socket
requires that the end-plate be used as a socket, or end-socket,
which to attach an external source of gas, for example, requires
removal from, then to initiate or reinitiate discharge, reinsertion
in the airgun. Unless the treatment area is large or the
muzzle-head stable in position without being attended to, removing
and reinserting the barrel-assembly in the airgun can make recovery
of the treatment site target time consuming whether the
barrel-assembly is of the radial discharge or simple pipe type.
[3545] Recent developments in fiber or flexible endoscopes indicate
that these should become available in diameters that will allow
direct viewing of the lumen wall through a barrel-tube (Seibel, E.
J. 2008. "1-mm Catheterscope," Proceedings of the International
Society for Optical Engineering (Society of Photo-Optical
Instrumentation Engineers SPIE), Optical Fibers and Sensors for
Medical Diagnostics and Treatment Applications VIII, Gannot, I.
(ed.), Progress in Biomedical Optics and Imaging 9:11, Session
6852, Presentation 7), with magnification possible that exceeds
present requirements (Engelbrecht, C. J., Johnston, R. S., Seibel,
E. J., and Helmchen, F. 2008. "Ultra-compact Fiber-optic Two-photon
Microscope for Functional Fluorescence Imaging in Vivo," Optics
Express 16(8):5556-5564).
[3546] The incorporation of radial projection units into any
(minimally ablation or ablation and angioplasty-capable)
muzzle-head confers an ablation and angioplasty capability, but has
greater utility in ablation or ablation and angioplasty-capable
barrel-assemblies, wherein the use of different tool-inserts can be
coordinated with other ablative means, such as thermal and
cryogenic. Combination-form ablation or ablation and
angioplasty-capable barrel-assemblies can additionally accommodate
interchangeable rotational or other atherectomy, thrombectomy, and
endoscopic devices, for example, which have been modified for
incorporation thus rather than for passage along a guide wire.
[3547] For this reason, radial projection units, while shown in the
muzzle-head of FIGS. 49, 65, and 66 for example, are addressed when
fully ablation or ablation and angioplasty-capable
barrel-assemblies are described. Similarly, `heat-windows, as
addressed below in the section entitled Thermal conduction windows
(heat-windows) and insulation of the muzzle-head body in thermal
ablation or thermal angioplasty-capable barrel-assemblies, can be
incorporated into any muzzle-head to impart a thermal and cryogenic
ablation and atherectomy capability that is made more versatile
when accompanied by the coordinated functions available in an
ablation or ablation and angioplasty-capable barrel-assembly.
[3548] VII2g(3)(e)(i). Types and Functions of Radial Projection
Unit Tool-Inserts, Electrical and Fluidic or Piped
[3549] The radial projection unit must support the internal
functions within the tool-insert; hence, the types of tool-insert
had already to be addressed above in the section entitled Radial
Projection Units. Tool-inserts that do not require connection
through the radial projection unit to an electrical or to a fluid
line but are self-contained, can be used in either electrically or
fluidically operated radial projection units. Such self-contained
and thus system-neutral tool-inserts can be either completely
passive or inert, presenting no more than a cutting face, or can be
syringes for discharging medication or surgical cement, for
example, contained within the syringe once a threhold lifting force
has been attained.
[3550] While a fluid powered ejection or injection tool-insert with
break-seal or push-through plug in the base-plug can be prefilled
to function as a syringe that will release a substance into the
lumen or lumen wall other than that to follow from the line, a
fully self-contained system-neutral syringe isolates its contents
from the line. This
[3551] a. Prevents unwanted intermingling of syringe and line
substances and
[3552] b. Allows use of the line fluid as an hydraulic fluid to
actuate self-contained spring released injectors containing other
substances while
[3553] c. The line fluid itself serves as a larger volume injectant
delivered through a fluid injector. The fluid in the line can,
moreover, be changed by switching reservoirs as necessary with or
without intervening flush liquid as necessary, and
[3554] d. Allows the line fluid in a barrel-assembly or a radial
projection catheter to be used purely as an hydraulic medium not
requiring change or replenishment with each use.
[3555] Only sterilization is then required before proceeding to
another procedure. Electrical tool-inserts are intended for use in
electrically operated radial projection system units and
exceptionally, in fluid system units that allow connection to a
source of electrical power. Electrical power is supplied to the
lift-platform socket in a fluid projection unit when only an
electrically operated tool-insert can provide the function required
and only a fluid projection system is present. Since fluid and
electrical projection systems can run side by side, the need for
electrical power in a fluid operated projection unit is
exceptional. Distinctly fluid tool-inserts are not usable in an
electrical projection system. Unlike a base-plug in an inert or
compound mechanical tool-insert, the base-plug in an electrical
tool-insert is not an optional mechanical connector but required as
an electrical connector for insertion into the electrical
receptacle or socket in the top of the lift-platform.
[3556] The need for electrical connection means that electrical
tool-inserts are neither usable in a fluidic radial projection
system nor self-contained. Whereas bit tool-inserts such as
shavers, brushes, and flat-faced pushing arms with rounded edges
are both inert and self-contained, electrical tool-inserts that
contain a heating element, for example, lack moving parts and are
in this sense inert or passive but not self-contained. Even though
provided with electrical power line 214 and 215 to accommodate
tool-inserts incorporating electrical features, base receptacle at
the top of lift-platform 176 can be left vacant as shown in FIGS.
54 and 55 or can be used to accommodate a dummy tool-insert
base-plug for securing the tool-insert within lift-platform shaft
182 by friction fit.
[3557] Electrical tool-inserts that incorporate a small motor to
move the working face, for example, are neither inert or passive
nor self-contained, as are gas discharged electrical syringe
injectors and ejectors, especially those that gain space within the
syringe for medication by using the lift-platform to house the gas
generating chemicals, as described below. Both inert and
motor-containing electrical tool-inserts can incorporate the same
kind of membranes and springs to attain greater lift internally as
can inert tool-inserts. Electrical tool-inserts can additionally
incorporate gas-discharge and electrical spring release means to
attain greater lift internally.
[3558] Self-contained compound mechanical syringe tool-insert
injectors and ejectors are used by energizing the radial projection
unit lifting mechanism with the unit or units on the side of the
muzzle-head or radial projection catheter to be used positioned
flush against the tissue treated, here that of lumen wall 204.
Resistance by the wall is used to effect the release of syringe
contents. For clear visibility, the injectant contains contrast
dye. If not abutted against the lumen wall when the lifting
mechanism is energized, injection can proceed only if proper
positioning is achieved immediately thereafter; if not, then the
needle must immediately be fully retracted into the unit shaft.
[3559] VII2g(3)(e)(ii). Self-Contained Electrical/Fluid
System-Neutral Tool-Inserts, to Include Injection and Ejection
Syringes
[3560] Unlike flow-through fluid tool-inserts, which emit fluid
into the lumen or lumen wall during antegrade pumping of the
actuating fluid, electrical/fluid system-neutral tool-inserts or
syringes are completely enclosed or self-contained and can
therefore be used with any suitable actuating liquid or gas as the
motive medium, and the fluid can be heated or chilled as necessary.
This allows the use of air, for example, to actuate injection and
ejection syring tool-inserts in blood vessels. The fluids used to
actuate tool-inserts or use these to aspirate need not be the same.
Whereas inert bit and fluid tool-inserts are generally sterilized
and reused, mechanical syringe injectors and ejectors, which are
equally usable in electrically and fluidically controlled radial
projection system units, are prefilled, used once, and
discarded.
[3561] The dimensions, especially that radial (vertical) of a
tool-insert are widely variable according to the depth of the
lift-shaft or well. A relatively shallow unit such as that shown in
FIG. 55 is suitable, for example, for a radial projection catheter
for ensheathment of a barrel-assembly wherein the radial space
available is limited, whereas a taller unit, such as that shown in
FIG. 54 might be accommodated by a stand-alone radial projection
catheter without barrel-tubes and.more radial space Lifting-height
lifting height (radial distance, excursion, radial throw), that is
the distance from the bottom of the lift-shaft or well 182 that the
tool-insert is raised is independent of lift-shaft height or the
radial space available and has little significance for
functionality.
[3562] FIG. 54 shows a compound mechanical injection and FIG. 55 a
passive ejection syringe which do not require electrical connection
through base-socket 205, while FIG. 59 shows the same compound
mechanical injection syringe as that shown in FIG. 54 in a
fluid-operated unit. Not requiring connection to an electrical or
fluid line for its internal operation and neutral as to whether the
lift platform is raised electrically or fluidically, these
tool-inserts can be used interchangeably in either type circuit.
Electrical/fluid system-neutral syringes lack a plug at the bottom
because these self-contained tool-inserts require neither
electrical nor fluidic power.
[3563] In the compound mechanical spring-discharged syringes shown
in FIG. 54 of an injection tool-insert or injector and FIG. 55 of
an ejection tool-insert or ejector, a heating coil positioned
within compression spring 206 in FIG. 54 or within piston-plunger
197 in FIG. 55 would necessitate electrical connection, hence an
electrical base-plug such as 207 in FIG. 56. The fluid system
tool-insert drawing FIGS. 59, 60, and 63 depict the lift-platform
as having already been raised off the fluid chamber divider or
separator wall which serves as the resting base for the
lift-platform. Lift resisting strip-spring 187, fastened at its
center to the top of the separator and at its ends to the underside
of the platform is therefore shown with its end curved upward.
[3564] That outlet or outflow chamber 195 roof-plate fluid resistor
199 is cut away to avoid contact by or obstruction of strip-spring
187 is not seen in a side view. Since it is functionally optimized
to support any interchangeable tool-insert, the receptacle in every
electrical unit includes electrical contacts. In the system-neutral
syringe of FIG. 54, the lack of a heating coil means that the space
within spring 206 can be filled with the lower portion of syringe
therapeutic fluid holding bladder 208, increasing its capacity. The
equivalent fluidic injection tool-insert such as seen in FIG. 59
requires neither a coil to warm nor a spring to discharge its
contents and therefore optimizes the space available.
[3565] The need for electrical power would limit these syringes to
an electrical projection unit. A heating coil added to the syringe
shown in FIG. 54 would not only allow warming the contents but use
of the elevated piston as a heating element whether a warmed
ejectant had been discharged or the syringe empty. Sliding or
swing-over tool-insert retaining arms (lock-arms, tool-insert
lock-down arms, stops, tool-insert retaining clips) 186 are
fastened in depressions at the surface of the muzzle-head or radial
projection catheter about the opening into lift-shaft 182 within
swing-way depressions located at opposite sides of lift-shaft 182
by rivets used as axles.
[3566] These depressions complement proximate depressions in the
radial surface of tool-insert 184 such that swing-arms 186 can be
rotated on opposite sides of tool-insert 184 to span over the
joints separating the tool-insert from the muzzle-head to either
side thus locking down tool-insert 184 within lift-shaft 182. One
arm fore and one aft of the lift-shaft are usually sufficient to
assure retention of the tool-insert. The depressions for hold- or
lock-down arms 186 are equal in depth, so that the radial surfaces
of tool-insert 184 and muzzle-head are level. Tool-insert lock-down
arms 186 hold down tool-insert 184 within lift-shaft 182 both when
lift-platform 176 is raised and when its working face is applied to
the lumen wall and encounters tangential or shear forces that would
dislodge it.
[3567] Receptacle or socket 205, empty with this mechanical
tool-insert in use, is available as an electrical connector for use
with an electrical tool-insert, which would have a plug extending
downward from its base for insertion into socket or receptacle 205.
Compound mechanical injection syringe tool-insert 184 is enclosed
within two telescoping sections that protectively encase the
tool-insert injectant, the upper section receiving the lower,
opposing or interlocking rims serving to prevent the sections from
separating. Syringe plunger or piston (the intromitting lower
section as shown) 197 slides into syring barrel barrel (upper
section as shown) 196 smoothly with the clearance essential without
play.
[3568] Syringe barrel 196 contains at its top center aperture 211,
which sealed by any suitable means before use, is just large enough
in diameter to allow injection depth-limiting external flange or
stop 210 surrounding hollow injection syringe needle 209 at a
distance from the needle tip to pass through. The interior of the
injector is kept sterile by a tab of plastic film or metal foil
applied with a suitable temporary pressure-sensitive adhesive and
discarded after use. Syringe injectors and ejectors are single-use
disposable products packaged with the injectant or ejectant
prefilled. To assure that syringes for use in the bloodstream
contain the dose intended and no air, some injectant is passed
entirely through the needle before packaging.
[3569] Both for safety and to maximize the size of dose that the
syringe can accommodate, needle 209 is no longer than necessary.
Gaining additional space through the use of a fold-down lie-flat
needle such as one mounted to the syringe ceiling is not preferred
as less dependable in retracting, more prone to leaking about the
base, and possibly opening by accident. In a tool-insert supplied
with electrical current such as shown in FIG. 56, a base-plug
extending downward at the center from the bottom of the tool-insert
serves to electrically connect the tool-insert into the electrical
circuit. In a fluid tool-insert supplied with fluid current such as
shown in FIGS. 59, 60 and 63, the outlet of the fluid circuit is
configured as would a base-plug and capped off by a spring-loaded
trap door that retains the fluid in the circuit when no tool-insert
is present.
[3570] Fluid operated tool-inserts such as injection syringes that
contain a preload for initial delivery are sealed at the bottom to
retain the fluid contents within bladder 208. In a tool-insert not
requiring internal power, base-plug 207 when not omitted as shown
in FIGS. 54 and 55, can be a blank or dummy, which would insert
into empty receptacle 205 in FIGS. 54, 55, 59, and 60, used to
retain the tool-insert in the lift-platform receptacle by friction
fit; otherwise, old-down arms or clips 186 serve to secure
tool-insert 184 within lift-shaft 182. Helical compression spring
206 is fastened, down to the floor of syringe piston 197 with its
upper end similarly fastened to the underside of syringe bladder
208, containing a measured dose, for example, of a medication, an
amount of surgical cement, or a tumefacient.
[3571] To assure that the contents at the center of bladder 208 and
not just the contents overlying syringe compression spring 206
about the circumference are fully ejected and the assigned dose
released, either spring 206 drives the bottom of bladder 208 up and
past syringe needle 209 and bladder puncturing lance (blade,
lancet) 213 fastening hillock 212 or collapsible syringe bladder
208 has a central solid plate at the bottom for driving the
overlying contents up and out. The material identity, density, and
thickness of bladder 208 are selected based upon puncture
resistance at the temperature for injection.
[3572] Syringes containing a heating element and those close to
sources of heat such as from a parallel fluid circuit must be
thicker or made of stronger thermoplastic sheeti, generally 1.5 mil
thick low density polyethylene. Those close to sources of cold must
have a bladder that is less resistant to puncture at colder
temperatures. Needle 209 must withdraw without resistance, and
bladder 208 must not be so resilient that upon return to the
retracted position or reseating by strip-spring 187, needle 209 can
rebound through needle tip aperture 211. Surmounting injection
syringe bladder 208 is hollow injection needle 209 with integral
bladder puncturing lance (blade, lancet) 213 extending from its
lower edge.
[3573] When bladder 208 is made of a material, typically polymer
sheeting such as polyethylene or polypropylene, which punctures
(Tabatabaeia, S. H., Carreau, P. J., a, and Ajji, A. 2009.
"Structure and properties of MDO [Machine Direction Orientation]
Stretched Polypropylene," Polymer 50(16):3981-3989; Lange, J.,
Mokdad, H., and Wysery, Y. 2002. "Understanding Puncture Resistance
and Perforation Behavior of Packaging Laminates," Journal of
Plastic Film and Sheeting 18(4): 231-244) with much force against
the tip of needle 209, needle 209 is mounted to a syringe bladder
puncture seal of the desired puncture resistance mounted to the top
of bladder 208.
[3574] Such a seal may replace the material of bladder 208 or
increase resistance to puncture as an added layer. Needle 209 atop
bladder 208 is held in the vertical position, sealed all around to
prevent leaking, and fastened to the top of syringe bladder 208 or
a syringe bladder puncture seal (unshown) by embedment within small
encircling mass of gummy or rubbery adhesive caulk forming hillock
212 having the consistency of pliant silicone rubber. When
energized or sent current from the control panel, thermal expansion
wire 177 forces tool-insert holding and lift-platform 176 radially
outwards against lumen wall 204, upwards as shown. Spring 206 is
under no compression until lift-platform 176 begins to push needle
209 against lumen wall 204 through aperture 211.
[3575] For sufficient resistance to penetration of needle 209 into
lumen wall 204 to cause bladder puncture lance or blade 213 to cut
into the top of bladder 208 or the bladder puncture seal and to
control the depth of injection or that needle 209 penetrates into
and injects the tissue under treatment, here lumen wall 204, needle
209 is usually provided with external surrounding flange 210 at the
distance from the tip of needle 209 desired. The depth of injection
into lumen wall 204 is set by the distance thermal expansion wire
177 raises needle 209, and the length of needle 209 or the distance
to the tip of needle 209 of needle-encircling injection depth
limiting flange or stop 210. Flange 210 can be increased in width
to reduce sinking into soft tissue as would necessitate more
lift.
[3576] For a flange of given diameter, the softer is lumen wall
204, the less must be the force exerted by spring 206 and the
greater the ease with which bladder puncture blade or lance 213
cuts through bladder 208 or the bladder puncture seal. To assure
proper depth of injection, the resistance to penetration of the
tissue under treatment, here lumen wall 204 by the tip of needle
209 at distances less than from the tip to the flange must be less
than the force necessary for bladder puncture lance or blade 213 to
puncture bladder 208. Except with mineralized accretions, this will
be the case. As lift-platform 176 continues to rise driving tip of
needle 209 followed by needle flange 210 against lumen wall 204,
spring 206 continues to accumulate elastic potential energy,
eventually causing syring puncture lance or blade 213 to
puncturesyringe bladder 208 or syringe bladder puncture seal if
present atop collapsible bladder 208.
[3577] This sudden reduction in resistance to compression of
bladder 208 allows energized spring 206 to expand driving the
syringe plunger plate if present radially outward or abluminally
(upwards as drawn), causing bladder 208 to expel its contents
through injection needle 209 and into the tissue under treatment,
here that of lumen wall 204. The volume flow rate of emission is
governed primarily by the dimensions of needle 209 and the
diminishing force exerted by spring 206 in relation to the
viscosity of the contents contained within bladder 208. These
variables are all controllable, so that it should never be
necessary with a low viscosity injectant to continue raising
lift-platform 176 until syringe bladder 208 is fully emptied in
order to preclude the premature extraction of needle 209 due to the
sudden collapse when punctured of bladder 208; spring 206 should
sustain the depth of needle penetration.
[3578] The density and strength of the tissue injected may also be
adjusted by means of antecedent treatment accomplished with the aid
of neighboring ejection or injection tool-inserts. Helical
syringespring 206 shown in FIGS. 54 and 59 can be replaced with
springs different in number or kind. In an electrical radial
projection system such as shown in FIG. 56, conductors are provided
through lift-platform 176 that end in the electrical contact points
or contacts at the surface of base-plug socket or receptacle into
which base-plug 207 is inserted. Injection needle 209 must be fully
retracted before resuming movement of the barrel-assembly or
dedicated radial projection catheter.
[3579] The retraction of needle 209 is accomplished by recession of
lift-platform 176 rather than by means within syringe tool-insert
184; that is, the nonretractable or irreversible means within the
syringe used to raise syringe plunger 197 once bladder 208 is
punctured, consisting of the helical compression spring 206 shown
in FIGS. 54 and 59 or the gas release and expansion mechanism such
as described below and shown in FIG. 56 is be used to retract
needle 209. Ejectors do not require retraction; however, limiting a
system to ejectors negates versatility of tool-insert
interchangeability in a muzzle-head or radial projection catheter
of given size. A system for use only with ejectors incapable of
injection does not require radial projectors.
[3580] While genuinely independent control of each radial
projection unit in an electrical or a fluidic system necessitates
that each be connected in an independent circuit, one means for
adjusting the order in which each unit lifts even when connected in
series is to include in each unit a barrier that complies to a
different degree of force. Here strip-spring 187 holding the apices
of the coil turns of thermal expansion wire 177 up flush against
the bottom of lift-platform 176 can be varied in dimensions and
materials to obtain widely variable varied restorative forces or
deformation resistance values. When radial projection units are
sufficient in number, setting the mechanical properties of the
units and tool-inserts in a given circuit assists in making arrays
of contoured profile in cooperation with neighboring circuits
whether electrical or fluidic.
[3581] For a given level of current, all units in the circuit that
would actuate at a lower current level will lift; however, with
syringes, earlier collapse of injection tool-insert syringe bladder
208 means that tip of needle 209 will now be receded so much lower
within the injection syringe tool-insert that it can no longer
emerge. This allows the individual units to be used in a preferred
sequence. Turning now to FIG. 54, shown is a self-contained
disposable electrical/fluid system-neutral compound mechanical
ejection tool-insert (ejection syringe, syringe ejector). The same
system neutral or interchangeable injection syringe is shown
inserted into a fluid operated radial projection unit in FIG.
59.
[3582] Syringes that must keep warm or heat the contents of bladder
208 include a heating element connected to a source of electrical
current through an electrical base-plug such as that shown as 207
in FIG. 56; otherwise, a base-plug is not needed, the receptacle
where a base-plug would insert shown in 205 in FIGS. 54, 55, 59,
and 60. The system-neutral injection syringe shown in FIGS. 54 55,
and 59 requiring neither a power nor a dummy plug, lift-platform
176 electrical socket or receptacle for base-plug 207, provided by
current through leads 214 and 215 as a permanent component of the
lift-platform available for any interchangeable tool-insert
requiring power for internal components, is accordingly shown empty
as 205.
[3583] By comparison, a flow-through fluidic ejector is not
self-contained, instead drawing fluid from the fluid circuit or
line, so that the fluid can be delivered at any temperature
preferred whether hot or cold. An ejector must begin to release its
contents not once a certain depth of penetration into the lumen
wall has been reached, but rather whenever the operator directs
release. Not contingent upon a threshold contact force normal to
its working face as is an injection syringe, ejection syringe
actuation can be accomplished with a simpler mechanism without
needle 209, bladder 208, or bladder puncture lance blade 213 under
the direct control of the operator.
[3584] The lack of a needle also eliminates the need to keep the
point of emission safely retracted within the syringe body before
and after use, and frees the radial space within the tool-insert
occupied by a needle for storing a larger dose of medication or
volume of liquid for the same sized syringe as compared to an
injector. The syringe tool-insert is held down inside lift-shaft
182 by hold-down arms or lock-down clips 186. FIG. 52c shows a
permanent or non tool-insert accepting fluid ejector, which
releases fluid directly from the power supply line where the fluid
can be water, a solvent containing a therapeutic substance in
dissolution, or a liquid or gas fluid therapeutic substance.
[3585] An ejection syringe as shown in FIG. 55 consists of an upper
or receiving body section, or barrel 196 into which syringe piston
or plunger section 197 intromits or telescopes when lifted
(radially projected) in this electrically operated radial
projection system by lift-platform 176 under the force exerted by
thermal expansion wire 177 when energized through leads 214 and
215, controlled at the ablation or angioplasty control panel.
Syringe barrel 196 receives piston plunger 197 so that the ejectant
housed within bladder 208 is prevented from leaking out the sides,
these body sections prevented from separating and further sealed
against leaking by complementary interlocking ridges about the rim
of each.
[3586] As seen in FIGS. 55 and 63, roof or perforated emission
working face 216 of syringe barrel 196 has holes 217 through which
the medication or other therapeutic substance is forced out when
syringe piston or plunger 197 is actuated. The ejectant is kept
sterile and prevented from running out ejection holes 217 by a tab
of plastic film or metal foil applied with a suitable temporary
pressure-sensitive adhesive and discarded after use.
[3587] Electrical/fluid system-neutral syringe ejectors can
incorporate additional or alternative principles of operation (see,
for example, Yuk, S. H., Cho, S. H., and Lee, H. B. 1992. "Electric
Current-sensitive Drug Delivery Systems Using Sodium
Alginate/Polyacrylic Acid Composites," Pharmaceutical Research
9(7):955-957). An electrical syringe with internal heating element
or coil can heat the contents to alter and/or effect its release
into the lumen (see, for example, Shi, J., Liu, L., Sun, X., Cao,
S., and Mano, J. F. 2008. "Biomineralized Polysaccharide Beads for
Dual-stimuli-responsive Drug Delivery," Macromolecular Bioscience
8(3):260-267). When such specialized equipment is unavailable,
syringe contents can be changed in temperature by submersion in a
heating or chilling bath.
[3588] Both electrical and fluid systems can be used to cause
polyelectrolyte gels to tumesce (swell) and/or liberate medication
by changing the pH or by heating and/or wetting the primary
injectant, fluid systems not limited to syringe delivery and thus
able to provide a larger volume of liquid. Incorporation of a
radial projection capability is intended to assist in the removal
of tissue for biopsy and/or the removal of softer deposits or
debris adherent to the lumen wall.
[3589] This includes any residual atheromatous tissue following the
removal of calcified prominences by a primary atherectomy device,
whether incorporated into a combination-form barrel-assembly as
addressed below in the section entitled Through-bore, or
Combination-form, Barrel-assemblies: Barrel-assemblies which
Accommodate or Incorporate Means for Ablation, Thrombectomy,
Atherectomy, Atherotomy, and/or Endoscopy, or a separate laser or
rotational burr used prior to initiating implantion discharge (see
Safian, R. D., Freed, M., Lichtenberg, A., May, M. A., Juran, N.,
Grines, C. L., and O'Neill, W. W. 1993. "Are Residual Stenoses
after Excimer Laser Angioplasty and Coronary Atherectomy Due to
Inefficient or Small Devices? Comparison with Balloon Angioplasty,"
Journal of the American College of Cardiology 22(6):
1628-1634).
[3590] Radial projection unit tool-inserts and heat-windows can be
used to remove ductus-lining or obstructing material or tissue
whether in blood vessels or other ductus, such as salt deposits
along the walls of the ureters. Perforated flat-faced tool-inserts
can deliver heated or chilled gas to the treatment site. Since
atheromatous detritus accumulates beneath the endothelium, to
access and eliminate plaque must involve penetration through and
thus injury to the endothelium. Intuitively, such injury that
results in the actual elimination of the plaque should be
preferrable to endothelial tearing injury by a balloon that only
crushes the plaque into the media.
[3591] Intimal hyperplasia and restenosis likely to ensue even when
plaque has been fully eliminated, medication and usually stenting
are used to promote patency regardless of the means employed to
effect plaque removal. Side-sweeping brush-type radial projection
unit tool-inserts do not appropriate so much of the luminal
cross-sectional area as to completely check the flow of blood and
are quickly retractable. A rotational atherectomy burr is superior
for the removal of stoney plaque but can furrow or even perforate
the lumen wall. Another device that can be used in a
combination-form barrel-assembly, a laser, can perforate as well,
but is effective with all but the hardest plaque.
[3592] A directional atherectormy cutter is unlikely to cause such
injury, but requires a preliminary step, most guide wire-directed
devices such as this generally incapable of incorporation into a
combination-form barrel-assembly, or only so after modification to
work without a guide wire. The incorporability of separate devices
into a combination-form barrel-assembly is addressed below in the
section entitled Through-bore, or Combination-form,
Barrel-assemblies: Barrel-assemblies which Accommodate or
Incorporate Means for Ablation, Thrombectomy, Atherectomy,
Atherotomy, and/or Endoscopy.
[3593] While the use of a barrel-assembly equipped with radial
projection unit ablative tool-inserts and an embolic trap-filter
could be used to perform an angioplasty in preparation for stenting
by conventional balloon, using the barrel-assembly avoids the need
for withdrawal and reentry and effects plaque elimination. Whereas
a preliminary atherectomy to remove calcified plaque protruding
into the lumen that had prevented (obstructed) a balloon
angioplasty would ordinarily be followed by a balloon angioplasty,
the barrel-assembly, especially a combination-form that includes a
rotational burr, for example, is able to proceed to stenting
discharge without the need for withdrawal and reentry.
[3594] When the plaque does not contain mineral deposits and the
muzzle-head is not significantly smaller in diameter than the
lumen, the muzzle-head itself compresses plaque against the lumen
wall, albeit not with the radial force of a balloon. Ancillary
magnetic steering, such as by means of an external hand-held
electromagnet, addressed below in the section entitled Use of An
External Hand-held Electromagnet, or a built in magnetic navigation
system, as addressed above in the section entitled Comparison of
Extraluminal with Endoluminal, or Conventional Stenting, can also
be used to actively draw the muzzle-head up against the lumen wall.
However, these methods in themselves accomplish only a limited kind
of angioplasty in the conventional sense of crushing the
atheroma.
[3595] The barrel-assembly will usually incorporate thermal means
such as `heat`-windows and sockets for connecting sources of cold
gas to supplement ablation by means of radial projection unit
tool-inserts. To preserve the reduction in operating time when more
difficult plaque is present necessitates the incorporation of
additional means for removing plaque, recommending the use of a
combination-form, even though the larger diameter will limit the
number of barrel-tubes. In clearing in a single sweep the lumen of
adherent material, plaque, or hyperplastic tissue just in advance
of miniball discharge so that implantation discharge can follow
immediately, this application of multiple means minimizes operating
time.
[3596] Unless the material is a hard mineral such as a salt in a
ureter or hydroxyapatite (hydroxylapatite) in an artery, a
barrel-assembly with radial projection tool-inserts and
heat-windows will serve to remove it. While the means exist to
ascertain the composition, and therewith, the hardness of the
adherent material (see, for example, Baraga, J. J., Feld, M. S.,
and Rava, R. P. 1992. "In Situ Optical Histochemistry of Human
Artery Using Near Infrared Fourier Transform Raman Spectroscopy,"
Proceedings of the National Academy of Sciences of the United
States of America 89(8):3473-3477; Gopal, A. and Budoff, M. J.
2006. "Coronary Calcium Scanning," American Heart Hospital Journal
4(1):43-50; Budoff, M. J. and Gul, K. M. 2008. "Expert Review on
Coronary Calcium.," Vascular Health and Risk Management
4(2):315-324), such are often unavailable.
[3597] If uncertain, abrading radial projection unit tool-inserts
with differently configued projection tips can be placed in the
radial projection unit lift-platforms thus eliminating the need to
withdraw the barrel-assembly to change tool-inserts. Projecting
blank or flat-faced tool-inserts makes it possible to push the
muzzle-head in the opposite direction to allow blood or other lumen
contents to pass, aid in steering, cover over and distance
untargeted intimal arcs from treatment elsewhere about the
muzzle-head, stabilize the muzzle-head in longitudinal position,
adjust the distance between the lumen surface and treatment unit on
the opposite side, or cause a brush tool-insert on the opposite
side to be borne against the lumen wall with greater force.
[3598] The muzzle-head can be nudged in any radial location in
either of two ways. With one or a few radial projection unit
tool-insert holding and lift platforms or few to be raised, the
turret-motor is first used with the lift-platforms retracted to
rotate the muzzle-head to the desired rotational angle, and then
the unit or units desired are actuated. Encircling units can
achieve such action without preliminary rotation of the
muzzle-head. The simultaneous extension of blank tool-inserts that
encircle the muzzle-head to simulate the compressive action of
inflating a balloon, if over a short segment, is discounted as
merely crushing rather than actually removing plaque.
[3599] To minimize the risk of injury to the endothelium, a
preliminary lumen wall strength test as described below in the
section entitled In Situ Test on Endoluminal Approach for
Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation is performed at sampling points over the area to be
pressed against, with equivalency for the intervening area
interpolated. The risk of incision, puncture, or perforation is
reduced by increasing the area over which force is applied. The
force exerted against the lumen wall on the pushing side can also
be reduced by combining vectors contributed by arcuately separate
groups of units pushing in unison.
[3600] The coordinated use of multiple units each with a small
contact or interface area also allows the use individually or
severally for different purposes, imparting greater utillity during
any one procedure as well as for allowing different treatment
options. When raised, a group of multiple units is not limited to
the circular contact surface contour or profile of a single large
unit as when these are retracted. Extending the end unit platforms
to a progressively greater height allows units extended from a
smaller diameter muzzle-head to assume an arcuate form better
adapted to a lumen that is disproportionately large in diameter
compared to the muzzle-head.
[3601] The need for gradual adaptation to variation in the lumen
diameter, for example, can come about continuously or when moving
more centrally, such as from a branch into a common trunk, for
example. Individual units can also be controlled bistably as off
and retracted or fully on and fully elevated and variability in the
distance of lift or height among units can be structural, according
to the shaft height (depth) and/or optionally, the incorporation of
an extension mechanism, such as the lift-platform. A rounded off or
feathered contour toward the boundary of an array of units is
obtained by incorporating units with shaft depths of less depth as
the boundary is approached. Control that is more versatile in
providing continuously variability in the extent of lift requires a
precisely calibrated control, such as includes a vernier scale.
[3602] To reduce the risk of incisions when pushing the muzzle-head
to a side while in motion requires a large flat tool-insert surface
area with blunted boundary to distribute the force whether
acomplished by coordinating the use of multiple smaller units or
using a single unit having a large face area. In smaller lumina,
the use of a separate laser or mechanical cutting tool may be
necessary. In larger lumina, depending upon the specific condition,
single entry and withdrawal can be achieved through the use of a
combination-form barrel-assembly with laser or rotational burr, for
example, inserted, as addressed below in the section entitled
Through-bore, or Combination-form, Barrel-assemblies:
Barrel-assemblies which Accommodate or Incorporate Means for
Ablation, Thrombectomy, Atherectomy, Atherotomy, and/or
Endoscopy.
[3603] When, as can occur in the intrapulmonary bronchi, matter
such as fibrotic obstructs the lumen, the ablative function of an
ablation or ablation and angioplasty-capable barrel-assembly
equipped with thermal ablation and radial projection unit shaving
tool-inserts allows clearing the lumen and stenting with single
entry. Where the use of stent-jackets is precluded, subcutaneous
and/or suprapleural patch-magnets are used. Combination-form
barrel-assemblies, however, cannot be made to so small a gauge as
can the equivalent barrel-assembly without a through-and-through
central canal or bore. The preliminary use of a separate
atherectomizing device as would necessitate entry and withdrawal
prior to using the barrel-assembly should arise seldom if ever.
[3604] When the lumen diameter is too small to admit a
combination-form barrel-assembly, either an ablation or ablation
and angioplasty-capable barrel-assembly with only radial projection
units and heat-windows is used. The use of a separate laser or burr
or of an ablation, atherectomy, or angioplasty catheter containing
radial projection and/or nonprojection units without barrel-tubes
as mentioned above will require an initial entry and withdrawal
before entry for stenting discharge. However, if the condition
demands rotational atherectomy or lasing, and the lumen diameter
will admit a combination-form barrel-assembly, the need for a
separate procedure prior to stenting will be averted. When implant
discharge is to follow, use of the ablation-capable barrel-assembly
is more expedient.
[3605] Even when not contemplated preprocedurally, a
barrel-assembly, unlike an ablation or ablation and
angioplasty-capable catheter that lacks barrel-tubes, affords the
option to initiate the delivery of medication or stenting at any
moment. Here the term `brush` denotes a tool-insert with
projections mounted in close proximity to the same backing or block
where the detailed configuration of the ends or tips of the
individual elements or filaments can be or can be other than
bristle-like. These brushes, with various tip configurations over a
wide range of stiffnesses, longitudinal and arcuate lengths, and
projection extensions are swept over the lumen wall to remove
diseased tissue or debris by cutting (shaving) or abrasive
(scraping) action (whence the terms `side-shaver,` side-sweeper,`
and `side-scraper`).
[3606] When retracted, the outer or working tips of the brushes end
flush to the surface of the muzzle-head. Radial projection unit
tool-inserts with different tip configurations are interchangeable
and fit into the same tool-insert holding and lift platform socket
or receptacle. The radial projection units are not provided with
lift-shaft cover hatches to present a continuous surface when
retracted. When a tool-insert of with a working end having a
smaller area than the tool holding and lift platform is inserted,
to minimize the surrounding space available for the accumulation of
debris, the space is filled by extending the base of the
tool-insert upwards as high as does not interfere with the working
end.
[3607] Radial projection unit tool holding and lift platforms can
be configured to accommodate tool-inserts such as brushes of
different shape and/or type, and different shapes and types can be
installed in units entirely about the circumference, although
usually only two to four units are incorporated. Units can be
controlled individually or in groups. Individual tool-inserts such
as brushes, can be flat (wallpaper brush-configured) or square with
filaments, bristles, or inclined shaving edges angled according to
the direction determined by the oscillatory function of the
turret-motor. Thus, inserting brush or side-sweeping tool-inserts
of different stiffnesses and tip configurations over different arcs
about the barrel-assembly allows the discretionary differential
treatment of eccentric lesions.
[3608] The turret-motor can be used to direct the independently
controllable radial projection units toward eccentric lesions,
radiopaque and independently heatable heat-windows available if
needed to assist in viewing the rotational angle. Regardless
whether control of the turret-motor is by a
servocontroller-amplifier microcircuit inmate in the hand-grip as
in an ablation or ablation and angioplasty-capable barrel-assembly
or by connection through the airgun as with a minimally capable
barrel-assembly, reciprocating action can be obtained either by
detuning the velocity loop causing the motor to oscillate, or by
programming the oscillatory movement.
[3609] In either case, the action can be used with radial
projection unit-deployed shaving or abrading tool-inserts. While in
an angioplasty-capable barrel-assembly in use for an angioplasty,
the turret-motor is usually limited to use as a heating element,
when the side-sweeping or shaving tool-inserts are divided between
different radial projection units for use in sequence in the
treatment of eccentric lesions, and the path to the treatment site
precludes rotation of the barrel-assembly, the turret-motor is used
to rotate and thus select the radial projection units for use at a
given time. Otherwise, rotation is of the barrel-assembly as a
whole by manual rotation (twisting, torqueing).
[3610] In a battery-powered angioplasty-capable barrel-assembly
intended for use independently of an airgun to perform an
angioplasty, rotation of the muzzle-head requires incorporating the
positional control into the onboard control panel mounted to the
hand-grip-shaped battery pack at the proximal end of the
barrel-assembly. Then both manual and remotely switched
motor-driven longitudinal and rotatory sweeping of the lumen wall
are provided. Gross transluminal or rotatory movements are normally
manual, finer longitudinal movements accomplished by means of the
linear postioning table stepper motor, and rotational movements by
means of the turret-motor.
[3611] Unlike an inflexible blade that sees the maximum resistance
along its contact edge and would cause injury if obstructed by
tenacious apatite, for example, a brush sweeps away plaque that is
soft while sweeping over plaque that is hard compared to the
bristle stiffness. The turret-motor circuit breaker prevents any
extra-bristle source of resistance from producing tears of the
endothelium and intima. Resisting side-sweeping tool-inserts, means
for identifying the presence of mineral deposits with the potential
to disallow the use of such tool-inserts are necessary.
[3612] Computed tomography allows plaque calcification and other
kinds of adhesions or protrusions into the lumen not only to be
qualitatively confirmed but characterized as to shoulder to base
distribution and percent content of calcium and hydroxyapatite
(see, for example, Raggi, P. and Berman, D. S. 2005. "Computed
Tomography Coronary Calcium Screening and Myocardial Perfusion
Imaging," Journal of Nuclear Cardiology 12(1):96-103; Huang, P. H.,
Chen, L. C., Leu, H. B., Ding, P. Y., Chen, J. W., Wu, T. C., and
Lin, S. J. 2005. "Enhanced Coronary Calcification Determined by
Electron Beam CT is Strongly Related to Endothelial Dysfunction in
Patients with Suspected Coronary Artery Disease," Chest
128(2):810-815; Thompson, B. H. and Stanford, W. 2004. "Imaging of
Coronary Calcification by Computed Tomography," Journal of Magnetic
Resonance Imaging 19(6):720-733; Rumberger, J. A., Sheedy, P. F.
2nd, Breen, J. F., Fitzpatrick, L. A., and Schwartz, R. S. 1996.
"Electron Beam Computed Tomography and Coronary Artery Disease:
Scanning for Coronary Artery Calcification," Mayo Clinic
Proceedings 71(4):369-377;) or multi-detector CT-angiography
(Miralles, M., Merino, J., Busto, M., Perich, X., Barranco, C., and
Vidal-Barraquer, F. 2006) "Quantification and Characterization of
Carotid Calcium with Multi-detector CT-angiography," European
Journal of Vascular and Endovascular Surgery 32(5):561-567.
[3613] The application of a magnetic field to the muzzle-head
through use of an extracorporeal hand-held electromagnet as
addressed below in the sections entitled Steering and Emergency
Recovery of Implants with the Aid of an External (Extracorporeal)
Electromagnet and the B.sub.0 magnet of a magnetic resonance imager
as addressed below in the sections entitled Use of an External
Electromagnet to Assist in Mishap Recovery and Stereotactic Arrest
and Extraction of a Circulating, Dangerously Mispositioned, or
Embolizing Miniball allows atheromatous lesions to be compressed
much as does a balloon. While always an option, like the
simultaneous extension of encircling blank tool-inserts to simulate
the compressive action of a balloon, treatment thus is discounted
as merely crushing rather than actually removing plaque.
[3614] Provided no significant buildup of hardened plaque is seen,
using a minimally ablation or ablation and angioplasty-capable
barrel-assembly, an atherectomy and stenting can be accomplished
with single entry. Abrasion and shaving with suitable tool-inserts
is useful for localized lesions susceptible of removal thus, which,
however, excludes hardened plaque. Dependent upon its prominence
and extent, stoney plaque may necessitate a bypass graft or
ablation by rotational or directional cutter. If a significant
buildup of hardened plaque is seen and the lumen is too narrow to
admit a combination-form barrel-assembly, then a preliminary
atherectomy with a separate device such as a rotational burr or
laser must precede stenting or a bypass graft is required.
[3615] The force with which the brushes are projected and held
beyond the surrounding outer surface of the muzzle-head is limited
by the force exerted and pliancy of the thermal expansion wire or
bimetallic tang used to raise or project the lift platforms. The
configuration, dimensions, and materials of the tool-inserts and
these elements are devised to minimize the risk of gouging injury.
A thermal expansion wire affords the highest coefficient of thermal
expansion, hence, makes possible the greatest displacement or
excursion of the lift-platform, for its size. Based upon the
polarity of the applied voltage when maximum, a crystal, by
comparison, typically changes from thicker to thinner by one
thousandth (see, for example,
http://www.micromanufacturing.com/showthread.php?t=517.
[3616] Alternative actuators based upon dielectric elastomers,
electroconstrictive or conductive polymers, polymer gels (gel
motors) or hydrogels may be substituted for a thermal expansion
wire, which more stable and simpler, provides a usable coefficient
of expansion (Bauer, H. J. 1977. "Mechanical Motions in Small
Inaccessible Volumes," i Journal of Physics E: Scientific
Instruments 10(4):332-334, page 333), even though it requires
cooling to effect retraction quickly. The protrusion of the
bristles beyond the plane of the muzzle-head can be controlled not
by adjusting tool-insert excursion through control over the degree
of thermal wire expansion alone but also through using a
tool-insert with projections of the length required.
[3617] Thus, the depth of penetration into the lumen surface can be
set, for example, by the length of the bristles in a side-sweeper
brush-type tool-insert rather than by adjustment to the extent of
lift allowed. The interchangeable tool-inserts can be variously
configured as, for example, subminiature curved or semicircularly
tipped wallpaper smoothing (smoothers) or square-head type brushes.
Using different materials in different thicknesses and lengths, the
rigidity of the bristles is widely variable. Abrasive bristles or
razors for removing plaque of given hardness as predetermined by
computed tomography are provided as interchangeable tool-inserts. A
barrel-assembly with multiple radial projection units allows plaque
of different hardness to be removed with single entry.
[3618] The bristles must not be friable or susceptible to fatigue
fracture, polyamide (nylon) being but one of many suitable polymer
materials for making these. Bristles made of plied materials or
projections of coextruded tubing in different diameters expand the
degree of abrasiveness attainable. When reversing direction would
cause the bristles to impose vectors that would pierce the lumen
lining, the tips are blunted. The sharpness around the periphery of
each bristle may be varied to affect its action as a drag-scraper.
When the bristle tips are round and sharp but the lesion is soft so
that dragging such a tip along the surface of the lesion only
undercuts the surface to either side without actually removing the
plaque, the faces of the bristle tip normal to the long axis of the
lumen can be formed into a sharp-edged cup with cutting edge as
shown in FIGS. 51B and 51C.
[3619] If the plaque or obstructive tissue is indurated or the
accreted material hard, then cup-configured bristles, which could
grab hold of and pull at that matter, are not used. Diametrically
opposed brushes can differ in bristle materials, conformation to
include thickness, and stiffness. As shown in FIG. 52, the entry
into lift-shaft 182 includes rotating hold-down arms (checks,
stops) to lock the insert within the lift-shaft and limit the
radially outward distance to which the too holding and lift
platform can be raised. These are rotated to lock the tool-insert
in the lift-shaft and limit the distance that the working tips can
extend beyond the outer surface of the muzzle-head.
[3620] To expedite the passage of blood when deployed, the separate
projections or bristles of a brush type tool-insert can be grouped
into separate ferruled bundles or plugs that flare outwardly from
the point of insertion in the brush-block (rib, backing) to provide
gaps. Multiple small hypointimal or hypoendothelial injections
rather than the single axis injections obtained from
service-catheters can be accomplished with a piped radial
projection unit injection head tool-insert, as addressed below in
the sections entitled Radial Projection Units and Radial Projection
Unit Tool-inserts.
[3621] Use of a hypointimal or hypoendothelial injection head, or
to treat the lumen surface, a perforated blank insert tool in a
radial projection unit that is piped, or equipped with rear supply
line, as addressed below in the section entitled Radial Projection
Units, allows a wider area of the lumen surface to be covered. To
prevent fouling of the pipe, conserve injectant, and allow good
control over dosing even when delivered as sequential aliquots from
a single load, the delivery of a liquid substance (medication,
swellant, sclerosant, cement, and so on) is through a
service-catheter inserted into the pipe, as addressed above in the
section entitled Preparation of Service-catheters for Use as
Transbarrel-assembly Hypotubes.
[3622] A hypointimal or hypoendothelial injection or syringe
tool-insert can be used to quickly treat a miniball array covering
a larger area. When the treatment seeks to close and mend or bond a
delamination of the lumen wall, an injection head tool-insert can
be used to deliver the bonding agent locally over a wider area more
quickly than can injection through a service-catheter. With thicker
walled ductus, the use of a bonding agent dense with contrast dye
having a setting time adjusted to a few seconds may allow the
lamina or tunics bounding an implant or delamination (dissection)
to be compressed into more tightly bonded relation. To do this, the
bonding agent is injected through a service-catheter or a radial
projection unit injection-head tool-insert, the tip of the
injection -head advanced toward the radially outer lamina, and the
injection device bulb or syringe pipetted or connected to an
aspiration pump to draw the outer layer inward compressing the
layers together.
[3623] To prevent the sharp injection tip from puncturing the outer
layers, aspiration is not initiated until the injection device is
retracted. The technique is not intended where visibility is
inadequate, the operator unpracticed using a synthetic model, or
for use in blood vessels. A piped radial projection unit can be
capped off or stoppered with a blank tool-insert. An advantage of
piped units is that accelerated retraction of the projected
tool-insert can be achieved by feeding chilled gas through the pipe
to chill and contract the thermal expansion wire, eliminating the
need to insert a cooling catheter that could not have been
prepositioned, as pertains to a minimal ablation or ablation and
angioplasty-capable barrel-assembly without a side-socket.
[3624] The momentary application of cold is used to retract the
projected tool-insert, whereas sustained cold is used for
cryoplasty, for example. Since piped units require a side-socket
for use whenever the barrel-assembly is engaged in the airgun, even
though these can be incorporated into minimally ablation or
ablation and angioplasty-capable barrel-assemblies, piped units are
addressed here in conjunction with ablation or ablation and
angioplasty-capable barrel-assemblies. A perforated tool-insert in
a piped unit allows tissue or lumen surface materials to be
aspirated or fed back from the lumen wall or fluids delivered or
fed forward to the lumen wall.
[3625] During the application of any transluminal process,
aspiration through these can be added to that through
service-channels or the central canal in a combination-form
barrel-assembly and trap-filter to eliminate potentially embolizing
debris. Fluid medication or a therapeutic chemical to which the
lumen should be exposed for only a prescribed or an optimal
interval can be delivered to the lumen surface through one or a
plurality of perforated tool-inserts and aspirated through the same
tool-inserts, or a continuous flow over a controllable path can be
established using certain perforated tool-inserts in piped radial
projection units to deliver and others to aspirate the fluid.
[3626] When the barrel-assembly is moved backwards (proximally),
perforated tool-inserts can be used to spray coat the lumen wall or
release medication just before the exit ports pass and the
miniballs are discharged. To reduce the risk of incisions, such
spraying action during transluminal movement is normally performed
with the perforated tool-insert retracted, which is the default
switching position that must be turned off to allow spraying with
the tool-insert extended (in the raised position). Moving the
barrel-assembly is moved forwards (distally), unused barrel-tubes
can serve this purpose. Use of the same barrel-tube to alternately
discharge miniballs and other substances without a service-catheter
to line the barrel-tube risks jamming.
[3627] To minimize the distance material must be drawn proximally
with vacuum force applied, aspiration for diagnostic evaluation or
treatment is usually through a service-catheter which is withdrawn
from the pipeline as soon as a sufficient sample is drawn into the
distal end. Another primary use for radial projection units is to
allow the discretionary raising of cutting (side-cutter) or
sweeping brush (side-sweeper) tool-inserts, which must be kept
recessed when not in use. These include brush configured shaving
tools that consist of a back-block holding many individual
projection razor edged tips or having razor edged bridges mounted
to its front side for shaving the lumen surface.
[3628] The same or different units can be used not only to retrieve
test samples at any point, prepare the surface, apply medication,
and so on, but also to provide more or less aggressive cutting
heads during the procedure, typically an ablation or an
angioplasty. Greater extension beyond the outer plane of the tool
holding lift-platform is obtained by incorporating a telescoping
tool holding lift-platform, an insulated thermal expansion wire of
larger coil diameter required. Directing a barrel-tube to the rear
of a radial projection unit rather than to an exit port, whether
singular or plural, represents a minor modification to a
barrel-assembly, which in larger diameter embodiments could have
some barrel-tubes used for discharge and some as supply lines with
only those with exit ports used for discharge.
[3629] However,
[3630] 1. A means for switching what is in effect a diverted
barrel-tube between aspiration and discharge configurations, for
example, impractical.
[3631] 2. The diversion of a barrel-tube eliminating its use for
discharge.
[3632] 3. Sufficient barrel-assembly internal diameter at a
premium, and
[3633] 4. The barrel-tubes and central canal available for
aspiration or other use as service-channels, the need to divert
barrel-tubes solely for aspiration would be infrequent and done for
an array of functions this could provide. A piped radial projection
unit with a side-cutter or side-sweeper tool-insert installed can
be used to deliver medication or hot air at the same time that it
is used to ablate the lumen wall, and the resultant brushed or
shaved debris can be removed by aspiration into a
service-catheter.
[3634] Using a barrel-tube with exit port instead, it is also
possible to insert a service-catheter that slightly extends a sharp
serrated or scalloped front edge beyond the muzzle-port to obtain
scrapings that are then withdrawn by bulb or syringe pipetting or
attaching the service-catheter to an aspiration pump, for example.
It is also possible to use either the exit-port or radial
projection unit tool-insert (side-cutter or side-sweeper) to remove
tissue which is then aspirated through the other component. The use
of a cutting or sweeping tool-insert with perforated back block
allows fluids to be delivered to the treatment site or tissue to be
aspirated away prior to or during ablation or angioplasty.
[3635] A perforated radial projection unit tool-insert, whether
blank or conformed for a second purpose, can be used to discharge
medication that is drawn past the cutting tool in a central radial
projection unit and aspirated away into a barrel-tube or a
service-catheter inserted in the barrel-tube. The direction of this
action can be reversed. In feed-back use, the rear supply line or
access channel allows aspirated material, whether tissue for biopsy
or removal or the removal of excess lubricant, medication,
fixative, or adhesive, for example, to be drawn into a
service-catheter for withdrawal, as addressed below in the section
entitled Radial Projection Unit Tool-inserts.
[3636] Feed-forward use of the rear access channel (pipe, pipeline,
supply line) allows therapeutic and/or temperature changing gases
or liquid medication, lubricants, or other chemical to be delivered
to the treatment site at the lumen surface. An injection syringe
tool-insert such as that shown in FIG. 54 can be horizontally
chambered or compartmentalized with each compartment containing a
different substance and provided with a separate injection needle.
Substances not be be mixed before but rather to react once injected
can be delivered thus. Multiple miniature injection or ejection
syringes or microneedles common to a single chamber or compartment
injection syringe tool-insert achieve more uniform release into the
lumen wall.
[3637] Depending upon the extension of the needle points beyond the
mouth of the lift-shaft at the surface of the muzzle-head, the
needles can serve as hypoendothelial, hypointimal, submucosal
medial, or perimedial hypotube injectors. With such means, the
lumen wall can be suffused subinimally or submucosally with one or
more liquid or gas drugs, adjuvant, other therapeutic substances or
tissue cement, by one or more injection tool-inserts while coated
at the surface with these or other substances through ejection
tool-inserts or a barrel-tube with or without service-catheter. In
the vascular tree, abrasion or aspiration to remove diseased tissue
can be accompanied by a run-ahead embolic filter-trap or
trap-filter to catch any loose debris.
[3638] Another advantage in piped radial projection units is the
quicker automatic retraction of extended tool-inserts upon
resumption in transluminal movement to avert the risk of incisions
by the direct delivery of chilled gas through the pipe to the
thermal expansion wire used to raise the tool-insert. As explained
below in the section entitled Automatic Disabling of
Implant-Discharge, Radial Projection Units, and Turret-motor,
motion sensors on the muzzle-head provide the actuating current to
an electrical valve controlling the outlet from a cylinder of
chilled or chilling gas that has been preconnected to the
barrel-assembly. An electrical valve has the advantage that it
allows the release of gas from the cylinder to be controlled in
duration (open time) and pressure (aperture area).
[3639] The alternative of using the motion sensors to cause a
warning light on the onboard ablation and angioplasty
barrel-assembly control panel to flash is not preferred, as this
results in a delay for the operator to manual respond. When the
source of chilled gas, whether a cold air gun or small cylinder
attached directly to the barrel-assembly without tethering cannot
be preconnected, an additional delay results. Yet another advantage
in piped radial projection units is the oppportunity for
tool-insert holding and lift platform projection or retraction fail
recovery by bulb or syringe pipetting or connecting the pipe to an
aspirating pump should the lift-platform for any reason fail to
retract or descend as necessary, or reversing the pump to blow,
forcing a nonelevating lift-platform to rise.
[3640] When the pipe need not be used to deliver chilled or heated
gas, the small pump can be connected when the procedure commences.
In some instances, the same gas used to affect the temperature at
the treatment site can be used to force the lift-platform into the
elevated position. A malfunctioning lift-platform in a nonpiped
unit must have ferromagnetic material incorporated to be lifted by
the magnetic attraction of an external hand-held electromagnet and
lowered by reversal of the magnetic field, which depending upon the
context, can disrupt implantation. Unless the piped units are
provided with a dedicated independent line that may course the full
length of the barrel-assembly in a loop, to pipe a radial
projection unit coopts a barrel-tube that might otherwise have been
used for discharge.
[3641] However, since the pipe does not continue forward into the
muzzle-head, the diameter of the muzzle-head need not be that of
the equivalent muzzle-head with an additional discharge exit port.
Depending upon the absolute diameter of the pipe line required,
when a bank of radial projection units are to be used together for
the same purpose, each can receive a branch from a single pipe.
Advantage is also taken of the supply line, with or without use of
the lifting capability, to discharge chilled or heated gas against
the rear face of a heat-window configured to be interchangeable
with other tool-inserts. The enhanced utility afforded by the
projection capability generally renders providing nonprojectable
heat-windows with a rear supply line uneconomic as underutilizing
the space taken.
[3642] The tool-insert holding lift-platform is permanently
installed in the shaft, and the pipe connected to the rear of the
platform moves up and down with the platform. When piped, the
tool-insert is either unperforated to serve as a gas-operated hot
(thermal, thermoablative) or cold (cryogenic, cryoablative)
ablating `heat-window or is perforated to allow materials to pass
in either direction. A perforated blank allows coating the lumen
wall with medication, for example. A tool-insert with innoculation
nozzles allows the hypointimal or hypoendothelial injection of
medication or a tissue swellant, sclerosant, or cement, for
example.
[3643] For reasons stated in the section below entitled Slidable
Ablation or ablation and angioplasty-capable Barrel-assembly Power
and Control Housing, fluid operated radial projection units are not
incorporated into narrower ablation or ablation and
angioplasty-capable barrel-assemblies. Instead, the barrel-assembly
is first introduced and advanced to the treatment site while most
readily steerable and least resisted, and then if needed, a
size-matched combination-form radial projection catheter with fluid
units, as addressed below in the section entitled Radial Projection
Catheters, is slid over the barrel-catheter as it were a guidewire.
Fluid operated radial projection units can be provided in larger
barrel-assemblies.
[3644] Whether built into the barrel-assembly or the radial
projection catheter, a fluid line can operate fluid units, and can
deliver and remove fluid materials to, through, and from units on
an intermittent or continued basis that syringes cannot achieve.
Connected to an aspiration pump, the line can be used to aspirate
diseased tissue as the cutting or brushing tool-insert continues to
remove the tissue. The tissue retrieved can be used for analysis.
When in order to eliminate the need for hosing to and/or from the
barrel-assembly a fluid system is built into the Power and control
housing hand-grip, a cartridge system for fluid replenishment and
removal is provided. Whether onboard or connected, reversal of the
pump or a an attached aerosol canister allows the line to be used
for cryogenic angioplasty, the delivery of medication, a swellant,
sclerosant, and/or cement, for example.
[3645] A piped radial projection unit has the advantage that
chilled gas can be delivered through the pipeline to retract the
lift-platform more quickly than does the insertion of a cooling
catheter down a barrel-tube or the central canal when the radial
projection unit is not piped, unless the cooling catheter can be
prepositioned within the line as not previously needed for another
purpose. To avert the unintended retraction of a tool-insert used
in conjunction with the delivery of a chilled gas, as during use of
a perforated tool-insert to perform a cryoplasty, for example, the
thermal expansion wire must be well thermally insulated and capable
of conducting a compensatory increase in current.
[3646] VII2g(3)(e)(iii). Self-Contained Electrical/Fluid
System-Neutral Tool-Insert Internal Stopping Membranes and Lifting
Springs
[3647] Whereas inert or passive self-contained tool-inserts require
only to be lifted and retracted, self-contained syringe injection
and ejection tool-inserts generally require to be lifted to expose
the needle or needles, then have an internal syringe plunger-plate
further lifted to eject the contents, and finally have the needle
retracted to prevent injury upon resumption of movement in the
lumen. In a mechanical syringe tool-insert, this action is achieved
with the aid of a strip-spring situated at the bottom or
`thumbrest` end of the syringe plunger in the base of the
tool-insert. In a mechanical syringe, when continued lift by the
lifting mechanism encounters resistance, a compression spring
beneath a syringe plunger-plate beneath the bladder containing the
medication begins to store energy.
[3648] A flange encircling the needle at a distance from the tip
corresponding to the depth into the lumen wall desired for
injection serves to restrict needle penetration and increase the
resistive force at this depth. Sufficient resistive force causes a
downward directed cutting edge extension of the needle to puncture
through the top of the bladder, freeing the spring to expand,
expelling the contents of the bladder. Varying the resistance of
this internal spring makes it possible to control the sequence in
which the tool-inserts along a given electrical or fluidic line
will be actuated. Where a spring serves both to resist further lift
until the lifting force is able to deform it whereupon it continues
the lifting, a membrane or surrounding seal thereof of prescribed
bursting force can be used to prevent further lift unless and until
this degree of force has been reached.
[3649] Within the variability in height of the lifting mechanism
alone, a membrane can set the force at which the tool-insert will
be raised. Since the internal spring can be flat, leaf, elliptical,
full elliptical, or spiral, the relative timing, degree of lift,
and outward radial force exerted by each tool-insert along a line
can be significantly varied. Stacking or serially arranging springs
allows the self-contained tool-insert to be raised incrementally as
the resistance of each successive spring is overcome by the driving
force exerted by the lift-platform. Distinctly electrical or
fluidic self-contained tool-inserts can also incorporate such
membranes and springs.
[3650] VII2g(3)(e)(iv). Electrical and Electrochemical
Tool-Inserts, to Include Gas Discharged Injection and Ejection
Syringes
[3651] All tool-inserts for use in circuit nodes having a lifting
mechanism must accommodate that mechanism regardless of whether the
need to be lifted inheres in the tool-insert function. To avoid
deforming the thermal expansion wires, electrical tool-inserts such
as heaters, which do not require lifting and would best remain with
working faces flush to the surface of the muzzle-head or dedicated
radial projection catheter, are made to completely fill the
lift-shaft but incorporate an electrical connector base-plug at the
bottom end of a spring-loaded lower half that telescopes into the
upper as seen in the system-neutral injection syringe described
above. This allows the lift-platform to rise independently of and
without lifting the tool-insert.
[3652] If made with a unitary body, these tool-inserts should be
used in a separate circuit that provides only electrical current
and excludes thermal expansion units. Turning now to FIG. 56, shown
is a compound mechanical-electrochemical injection syringe
tool-insert for use in an electrical radial projection system. Not
using a spring, the internal arrangement of components is
equivalent to that seen in the mechanical electrical/fluid
system-neutral injection syringe inserted into the radial
projection units shown in FIGS. 54 and 59 where compression spring
206 has been replaced by an electrically activated gas releasing
and detrusion or expulsion mechanism.
[3653] As shown in FIG. 56, thermal expansion wire 177 plays no
part in the action and is shown as a part of the projection unit
available for raising the lift-platform when other interchangeable
tool-inserts that use this action are in use. For such use, thermal
expansion wire 177 must be on a separate circuit rather than wired
in series with other electrically operated units. The syringe is
forced outward not by lift-platform 176 but by the gas releasing
reaction. The electrical power used is that supplied through wire
214 to the receptacle at the top center of lift-platform 176 into
which electrical base-plug 207 is inserted.
[3654] While replacing thermal expansion wire 177 with a meltable
wax partitioned chemical isolation chamber would allow a single
expulsive or lifting action to raise both the lift-platform and the
syringe piston, in which case the tool-insert body could be unitary
rather than telescoping; this would lose the advantage of
projection units that built into the muzzle-head or radial
projection catheter will immediately accept a series of different
type interchangeable tool-inserts. An alternative type radial
projection unit and tool-insert system could incorporate lifting
means whether spring or gas discharge based at the bottom of each
tool-insert, but duplicating and expending the lifting mechanism
with each tool-insert involves greater expense. An advantage of
electrical units is that electrical resistance can be used along
with differential mechanical resistance in the form of springs
having different restorative forces to adjust the current needed to
raise a given unit positioned anywhere along a series-wired circuit
such as that shown in FIG. 57.
[3655] Syringes emptied by means of internally generated gas
pressure such as that shown in FIG. 56 must be gas- as well as
medicinal contents-tight. Switching on the circuit of the unit
shown in FIG. 56 energizes thermal expansion wire 177, raising
tool-insert holding and lift-platform 176, collapsible syringe
bladder 208, and injection needle 209. With the outer surface of
the tool-insert in contact with lumen wall 204, injection needle
209 is driven into lumen wall 204 to the depth allowed by depth
limiting flange or stop 210. Filament microswitch embedding
melt-barrier 218 is used to separate chemicals and that when
combined generate the gas used to compress bladder 208, which
contains the medication and/or other therapeutic agent, such as a
tumefacient, surgical cement, protein solder, or any combination of
these to be injected.
[3656] As needle 209 continues to penetrate tissue such as that of
lumen wall 204, the mechanical resistance to further penetration,
which is proportional to the strength of the tissue, diameter of
depth limiting needle flange or stop 210, the flexibility resulting
from the material and dimensions of the spring metal electrical
contact arms of lever microswitch filament embedded in meltable wax
chemical compartment partition (separating wall, melt-barrier) 218,
and the lifting force exerted by coiled thermal expansion wire 177,
increases, eventually forcing lever microswitch embedded in
meltable wax chemical partition 218 to close, sending current
through the microswitch embedded in meltable wax chemical partition
218. Disintegration by melting of wax partition 218 causes the
chemicals to come into contact generating gas that drives plunger
197 outwards causing bladder 208 to expel its contents.
[3657] The net resistance posed by the foregoing factors of
mechanical resistance that precede the closure of partition with
embedded switch 218 and thus precede the initiation of heating is
preferably made selectable on the basis of lumen wall hardness
testing results, obtained as described below in the section
entitled Testing and Tests. Lever microswitch can be made of any
suitable heating filament material, to include Nichrome.RTM., or
Chromel.RTM., Alumel.RTM., copper, constantan, manganin, or
platinum, the current set for the materials in the microswitch and
wax used. Melt waxbarrier with embedded filament lever microswitch
218 continues upward to divide chemical separating chamber
partition roof 219, so that when melted, the gas generated by the
reaction escapes through the linear gap or aperture left behind in
roof 219.
[3658] Provided the base plunger plate at the bottom of bladder 208
is flush about the switch arms, extension of the microswitch
radially outwards past partition roof 219 allows its use to warm
the contents of bladder 208 at temperatures below that which melts
partition 218. Microswitch filament in partition 218 can be made of
a material that melts, allowing it to act as a fuse, breaking the
circuit in which it is wired and thus cutting off the continued
generation of heat other than that contributed through conduction
from thermal expansion wire 177. Lift-platform 176 can be made
either of a highly heat conductive metal to gain additional warmth
from thermal expansion wire 177 or of a heat insulative polymer to
isolate this source of heat. To achieve a difference in temperature
within bladder 208 and partition 218, the filament can be made in
consecutive segments that differ as to material and the use of
insulation within partition 218 and within bladder 208.
[3659] Depending upon the dictates for temperature in general,
barrier melting time can be adjusted by chilling the muzzle-head or
dedicated radial projection catheter prior to use or a cooling
service catheter can be inserted through the closest barrel-tube.
While mechanical and electrochemical syringes are shown as distinct
for clarity, the mechanical injection syringe tool-insert of FIG.
54 and ejector of FIG. 55, provided with an electrical plug at its
base, can also incorporate a heating wire to warm the contents of
bladder 208. One example of chemicals for placement on opposite
sides of chemical isolation partition or barrier 218 that generate
a gas when partition 218 melts, bringing the chemicals into contact
is acetic acid and sodium bicarbonate. These combine to yield
sodium acetate and carbonic acid, the latter immediately breaking
down into water and carbon dioxide gas.
[3660] Partition 218 can be made of numerous different materials or
combinations of materials mixed and/or layered, to include various
waxes, such as bayberry, soybean, paraffin, and blends and plies
thereof, and in dimensions to melt or break down at the temperature
reached by filament within partition 218. That the materials and
dimensions of partition 218 and the switch filament embedded within
can be combined to react over a wide range of current-induced
temperatures allows a wide range of temperatures to be applied to
the contents of bladder 208. Medication or other therapeutic
substances can be kept warm, if solid at room temperature can be
kept fluid, and this can include protein solder as addressed above
in the section entitled Use of Solid Protein Solders, in a
denatured or fluid state so that it can be injected.
[3661] An electrochemical tool-insert for delivering both gas for
lifting and heat is constructed with an overlapping gas-tight cap,
the roof of the lower capped over portion containing the chemical
separation chambers up through which the melt-barrier extends
through the roof. Plugged into an electrical projection unit,
passing current through the heating wire embedded in the wax
partition that separates the chemicals and runs up through the roof
melts the barrier, allowing the chemicals to combine and opening
the slot along the roof through which the partition had extended
allowing the gas to push up the gas-tight cover. The time of
heating and temperature reached prior to the melting of partition
218 and emptying of bladder 208, initiated upon closure of the
lever switch filament embedded within partition 218, are widely
adjustable, and depend upon the resistance to closure of embedded
switch 218, the rate of temperature increase generated by lever
switch filament within wax partition 218, and the melting point of
partition 218.
[3662] Protein solder, for example, requires heating to a higher
temperature over a longer period to be denatured to liquify and
flow, and therefore requires more of a time delay, obtained
primarily through the use of a barrier having a higher melting
point. Heating time prior to barrier melting and expulsion
contributes to the heat imparted to the contents of bladder 208.
The heat generated during this interval will also affect the
temperature of the expulsion gas, increasing its volume, hence
pressure for emptying bladder 208. Heating affecting both the
pressure of the expulsive gas and the viscosity of bladder
contents, the factors affecting heating time must be balanced
between the temperature within bladder 208 and the expulsive force
sought. Upon melting of partition 218, the gas rushes out through
an aperture in plunger-plate opened when partition 218 melts.
[3663] Filament lever switch embedded within partition 218 passes
down through bladder 208 and partition 218 and therefore can be
used to heat the contents of bladder 208 as well as to melt
partition 218. Delayed delivery substances should be distinctly
contrast dyed. The form and length of heating partition embedded
filament 218 inside bladder 208, typically coiled with radius about
one third to one half that of bladder 208, includes a number of
turns of a diameter that is contingent upon the pattern of heat
distribution desired. The pressure required depends upon the
dimensions of needle 209 and the viscosity and volume of bladder
contents to be expelled. Suitable materials for use as heating
wires are specified above in this section. The melting of a barrier
separating chemicals that when combined produce a reaction which
produces a gas or a gas and heat by heating such a wire coursed
through the barrier can be used to generate thrust and/or heat with
greater speed and intensity than could be achieved with the wire
alone.
[3664] The chemicals can be the same as those used in chemical
heating pads, hand, and foot warmers. These incorporate a barrier
that is broken manually to combine water and a supersaturated
solution of sodium acetate, calcium chloride, or iron in the
presence of an oxidation-accelerating catalyst. Because recharging
the chemical compartments and replacing the melt-barrier in the
nonremovable lifting mechanism at the bottom of a radial projection
unit is tedious and time-consuming, electrochemical release of gas
or gas and heat is relegated to tool-inserts rather than built into
the radial projection unit lifting mechanism. Exothermic reactions
that generate sufficient amounts of heat and gas can be used both
to heat the heating tool-insert and raise the lift-platform into
position.
[3665] The greater speed, force of thrust, and application of heat
that can be obtained by such means are offset by the loss of
control once the conditions for the reaction have been established
and the chemicals combined. By contrast, a heating wire remains
fully controllable, so that the heat it produces, or if an
expansion wire that can also serve to lift the heating tool-insert,
the displacement it imparts, remain continuously and reversibly
adjustable. Radial projection units in multiple discharge
barrel-assemblies can be chilled during use by inserting a cooling
catheter through a nearby barrel-tube or flowing chilling fluid
through a nearby fluid radial system supply line. The lifting
mechanism such as a thermal expansion wire serves no less to
withdraw the tool-insert on cooling than to elevate it when
supplied current.
[3666] When the ability to adjust the tool-insert in radial
extension or height is unimportant and the spontaneous recession of
the tool-insert working face upon the collapse of syringe bladder
208 is sufficient for safety without the need for additional
lowering, lift-platform 176 can be eliminated and its function
combined with that of the tool-insert internal plunger-plate
lifting means, such as a compression spring, in the form of larger
gas generating chemical chambers at the bottom of lift-shaft 182.
Emptying bladder 208, or a bladder divided into upper and lower
compartments, and lowering lift-platform 176 retracts needle 209 to
well within injection syringe tool-insert barrel 196.
[3667] Strip-spring 187 just below lift-platform 176 assists in
retracting the tool-insert when current through thermal expansion
wire 177 is stopped. This allows the use of a larger bladder that
is capable of delivering a larger quantity of injectant or
ejectant. Moreover, lengthening bladder puncture lance or blade 213
allows dividing this larger bladder into an upper section punctured
first and a lower section punctured upon collapse of the upper
section, where each section can contain a different substance or
component to be mixed, such as those of a two-part surgical cement.
Electrical actuation also allows adjusting the resisting force of
the lever microswitch spring and the distance separating the
contacts to delay discharge and allow additional warming time.
[3668] This delay allows heating the expulsion gas to attain a
volume, hence pressure of gas sufficient to empty the bladder. The
nichrome wire and melt-down partition separating the chemicals that
generate gas when mixed are adjusted in chemistry and dimensions to
bring the chemicals to a temperature that results in expansion of
the gas produced sufficient to collapse the bladder. A potential
but seldom needed advantage to a gas-expelled injector or ejector
is the ability to place the compartments separating the chemicals
that are combined to generate the expulsive gas within the
tool-insert holding and lift platform of the lifting mechanism
rather than within the syringe tool-insert, making available the
space that would otherwise be taken up by a spring, for
example.
[3669] However, positioning the syringe expulsion mechanism inside
the lifting mechanism rather than within the disposable tool-insert
creates the need for a lift-platform that can be removed for
cleaning and refilling. Since an injection needle protrudes out
through aperture 211 more than alternative tool-inserts, an
injector is most likely to require to be further lowered with the
aid of a lift-platform. However, due to the need for cleaning after
each use and refilling for the next, consolidation of tool-insert
lift-platform and expulsive lifting functions through means that
generate a force sufficient both to lift and to force the bladder
empty are more suited to one-time use disposable radial projection
catheters. Such consolidation precludes finer control over
tool-insert elevation and is not used to eliminate the lifting
mechanism in barrel-assemblies and reusable radial projection
catheters.
[3670] VII2g(3)(e)(v). Temperature Control in Electrical
Tool-Inserts
[3671] The regulation of heat in electrical tool-inserts is
accomplished by the same means as described above for the
turret-motor and recovery electromagnet windings as heating
elements in the section entitled Turret-motor and Recovery
Electromagnet Insulation, Leads, and Control of Winding
Temperatures when Used as Heating Elements in Ablation or ablation
and angioplasty-capable Barrel-assemblies. Electrical heating has
the disadvantage of lacking a practical cooling counterpart,
necessitating the use of a cooling catheter to rapidly drop the
temperature. Small scale electrical refrigeration is not
sufficiently developed or economical for incorporation into
electrical tool-inserts, pertinent references concerning various
approaches provided above in the section entitled Rapid Cooling
Catheter and Cooling Capillary Catheter for Cooling Heated
Turret-motor, Electrically Operated Radial Projection Unit-lifting
Thermal Expansion Wire, and Recovery magnets.
[3672] VII2g(3)(e)(vi). Fluid-Operated Tool-Inserts, to Include
Ejector-Irrigator-Aspirators and Injectors
[3673] Fluid operated radial projection units for use over a
smaller range of fluid pressures generally include the lifting
mechanism at the bottom. Since these are built into the units and
disengageable from the fluid circuit, the units include the valving
needed to switch between ejection with the fluid in the circuit
flowing in one direction and aspiration in the other. Units in the
muzzle-heads of barrel-assemblies and radial projection catheters
are limited to components likely to be necessary with tool-inserts
applicable to the type ductus for which the primary equipment is
intended. Such comprehends the need for a wide range of
capabilities, which will be reflected in the lift-aspiration
mechanism valving.
[3674] For example, units that will not be used with tool-inserts
capable of aspiration omit all fluid direction of flow switching
valves. Various fluid operated tool-inserts incorporate internal
means for projection and retraction. Ejection-aspiration switchable
tool-inserts seldom call for lifting and retraction. Use of the
term `flow reversal` here is distinguished from use of the same
term in conjunction with carotid angioplasty and stenting,
addressed below in section VII2j(1) entitled Incorporation of
Adscititious Capabilities into Barrel-assemblies, and aortic
regurgitation on the diastoles due to aortic valve impairment. For
this reason, the fluid-operated units and
ejection-irrigation-aspiration tool-inserts shown incorporate
switching valves and other elements not required in most practical
fluid units and tool-inserts.
[3675] The operating pressures and direction of flow reversal
capability for a certain combination of projection unit and
tool-insert vary according to the specific conditions and functions
to be encountered. Viewed normal to the long axis of the
barrel-assembly or radial projection catheter, a fluid circuit
operated tool-insert is bilaterally symmetrical.
[3676] It can therefore be rotated through 180 degrees to reverse
its response to antegrade or retrograde flow through fluid supply
line 203. At the same time, the fluid pump contained within the
power and control housing is reversible. The norm adopted for
descriptive purposes is that flow is antegrade and tool-insert
projecting and/or actuating from left to right and retractive
and/or aspirative when the flow through fluid supply line 203 is
from right to left. With fluidically operated units, injection and
ejection are not limited in volume as with a syringe, and
continuous delivery or removal is not limited to injection or
ejection. Fluid projection units are shown in FIGS. 52b, 52c, 59,
60, and 63, with injection tool-inserts shown inserted into those
shown in FIGS. 59 and 60, and an ejection tool-insert in that shown
in FIG. 63.
[3677] Provided the lifting mechanism incorporates the switching
valve elements essential to support flow reversal, most ejectors
will both irrigate and aspirate. Electrical syringes could be
devised to decollapse and use the vacuum to draw in material, but
limited to the internal volume of the syringe bladder, this is
discounted. Injector or single exit orifice (end opening) type
tool-inserts, which unlike syringes are not safely retracted back
into the tool-insert once discharged, can be used to irrigate or
aspirate only when integrated into a shaving or abrading tool face
that surrounds the orifice, protecting the lumen wall from injury.
Most fluid operated tool-inserts do not require an entry collar or
neck extending down at the base for adaxial insertion in the
lift-platform receptacle, but only an opening where the
lift-platform effectively supplies the sides of an entry way or
portal as a virtual plug.
[3678] Irrigation allows the continuous delivery of water or a
therapeutic fluid at the treatment site. The use of aspirators and
cutting or shaving aspirators in the arterial tree aspirates blood
along with the debris; however, the absolute volume of blood is
small, is not reintroduced, and the process not comparable to the
use of a cardiopulmonary machine that reintroduces damaged blood
cells. Irrigation or aspiration can also be accomplished through
neighboring projection units or side-socket accessed barrel-tubes
in an ablation or ablation and angioplasty-capable barrel-assembly.
Ejector-irrigator-aspirators have working face holes sized
according to the size of the debris particles the cutting or
abrading tool generates. Depending upon the lifting forces and
functions of other units in the same circuit, clogging can be
forestalled by increasing the line pressure.
[3679] Once clogged, a larger muzzle-head or combination-form
radial projection catheter without an available alternate circuit
must be withdrawn and cleaned or exchanged. Procedures that
generate much debris are more quickly accomplished with a bipartite
radial projection catheter or ablation or ablation and
angioplasty-capable barrel-assembly with multiple interchangeable
radial projection catheters each containing two or more fluid
circuits. Electrical shaving tool-inserts or shavers do not
aspirate but store the debris removed in a chamber behind the
cutting blades. By spacing the blades to configure the output
streams and particle inlet clearance, an
ejector-irrigator-aspirator with a cutting (shaving) face
eliminates the need for face-holes; however, it must be lifted when
shaving, necessitating an additional strip-spring with greater lift
resistance.
[3680] Separating the shaving functions between different
tool-inserts spares this added complexity. For example, an
electrical shaver with internal storage can be supported by fluid
aspirators and/or an embolic filter that remove residual debris.
Fluid tool-inserts include initially charged or measured
dose-prefilled flow-through injectors and ejectors, which deliver a
preliminary or therapeutically preparatory amount of a fluid
substance before transferring fluid directly from the line, and
ejector-irrigator-aspirators whether integrated into tool-inserts
with shaving or abrading faces. Both electrically and fluidically
controlled projection units can use inert bits and self-contained
syringe injectors and ejector irrigator aspirators; however, only
fluidically operated projection units can use fluid tool-inserts.
Following use to inject, injectors in the retracted position can be
used to irrigate but generally have a gauge unsuitable for use to
aspirate.
[3681] Such use and the use of ejector irrigator aspirators as
suction devices for holding the surface against the lumen wall have
the potential to cause injury. The ejector irrigator aspirator
shown in FIG. 63, just as any fluidic tool-insert, is capable of
intermittent or continuous fluid delivery. A fluid ejector or
injector can be prefilled with a measured dose of medication other
than that to follow from the line. In that case, the medication is
sealed inside the tool-insert with pressure sensitive-backed foil
or film at the base-plug inlet and face aperture outlet and stored
at the prescribed temperature. Otherwise, the ejector or injector
can deliver fluid intermittently or continuously as controlled.
[3682] In FIG. 63, syringe ejection tool-insert (defined to the
left hand side of FIG. 54 as 184 with other major part numbers) is
inserted into lift-shaft 182. Virtual flow-through base entry and
discharge portal or passageway 220 is established by contact and
continuity between the opening at the base of the tool-insert and
the wall about the receptacle through the center of lift-platform
176, providing flow-through base entry and discharge portal or
passageway 220. Retention within lift-shaft 182 is by means of
hold-down or swing-out restraining or stop arms 186, so that an
actual base-plug is not needed for friction fitting the tool-insert
within lift-platform receptacle constituting virtual base-plug
201.
[3683] When the fluid pressure in supply line 203 is high enough,
strip-spring valve 187 clears opening 201 leading into base entry
and discharge portal or passageway 220, but is prevented from
passing through the base of the tool-insert by spring door 221, so
that lift-platform 176 raises ejection syringe plunger or piston
197, expelling syringe pre-load 222. That is, when the pressure in
line 203 is only turned up enough to force strip-spring 187 to
clear opening 201, the tool-insert functions as an ejection
syringe. When the pressure in the fluid supply line 203 is
increased enough to overcome the resistance to opening of
spring-loaded trap door 221, the tool-insert becomes a continuous
discharge ejector-irrigator for whatever fluid is run through
supply line 203. At continuous flow-through pressures, the
tool-insert can be devised to serve as an ejector when the flow
through supply line 203 is in one direction and as an aspirator
when the direction of flow is reversed.
[3684] Unless the ductus is large enough in diameter to accommodate
a muzzle-head with or without ensheathment in a radial projection
catheter (addressed below in the section entitled Radial Projection
Catheters), which can accommodate independent fluid circuits with
flow in opposite directions, to change from ejection to aspiration
would necessitate withdrawing the barrel-assembly from the body,
exchanging tool-inserts, and reacquiring the treatment site, all
the time aggravating the entry wound as well as extending the
procedure. The need for withdrawal and reentry is then further
multiplied when a barrel-assembly is essential for ballistic
implantation, but the ductus too small in diameter to allow the use
of a muzzle-head that can incorporate the number of projection
units required or a duplex, or bipartite, barrel-assembly as would
provide whatever number of units were necessary, as addressed below
in the section entitled Distinction in Ablation or Ablation and
Angioplasty-capable Barrel-assemblies as Unitary or Bipartite.
[3685] Then an independent radial projection catheter, as addressed
below in the section entitled Radial Projection Catheters would
require to be withdrawn and exchanged with the barrel-assembly
however many times this became necessary. In this situation,
ejector-irrigators and cutting tools that are also capable of
aspiration by reversing the direction of flow through supply line
203 are of significant advantage. Added versatility thus favors
economy from the procedural duration, efficiency, and safety as
well as the purchase price standpoint. Thus an upward flow through
the tool-insert must pass through the perforations. In order to
assure the prompt resumption of outward flow, which necessitates
that the valve quickly close to the restrictive position, the valve
axle includes a stop so that during aspirating flow through the
circuit or line, that is, inflow through the tool-insert, the
expansive side of the valve cannot assume a fully off-vertical
position.
[3686] Instead, the expansive side is inclined toward its side or
stop side and is quickly levered back up against the stop by any
subsequent outflow. When incorporated into a prefilled injection or
ejection syringe tool-insert, the perforations are sealed and the
damper tacked in the closed position by a film such as of a dried
sugar solution, for example. A film sets a threshold line fluid
syringe tool-insert lifting force on actuation, and broken, leaves
the base-hole or base-plug to pose no resistance to outflow back
into the fluid circuit of the inflow through the perforations in
the working face when the direction of flow through the fluid
supply line is reversed to initiate aspiration. Provided only one
such directional reversal to go from resistance to flow-through and
threshold lifting force for the specific type tool-insert to
aspiration with no resistance is necessary, a one time use film is
adequate.
[3687] For uniformity in the radial projection unit
lifting-mechanisms, variable elements such as this film are built
into the tool-insert rather than the lifting-mechanism. However, it
is preferable that actuation with flow in one direction and
aspiration in the opposite direction be reversible without the need
to exchange tool-inserts. Strip-spring 187 setting the
lift-platform lifting pressure, a fluid resister to serve as an
actuation and aspiration switching valve is added to set the
tool-insert flow-through and syringe piston-plunger lifting
pressures. The direction-of-flow responsive switching valve is
automatically actuated by a reversal in the direction of flow
through the fluid supply line and can be reversed as often as
necessary.
[3688] This fluid resistor switch consists of polymeric baffle 199
with perforations sized for a sum cross-sectional area to impose
the required resistance to flow-through based upon the viscosity of
the fluid in the line, syringe contents viscosity and
compressibility if any, and the sum cross-sectional area of the
outlet pore or pores (apertures) in the working face. Also to allow
reversal of the fluid pump in the power and control housing, to
quickly reverse the directly of flow in fluid supply line 203,
damper-configured baffle resistor ejection-aspiration switching
valve 223 in FIG. 62, situated within base entry and discharge
portal or passageway 220 leading into the tool-insert adaxial to or
beneath spring loaded door 221 incorporates off-center integral
(molded in) axle 224.
[3689] The ends of axle 224 are journaled in the sides of base
entry and discharge portal or passageway 220. Axle 224 divides the
baffle 223 into smaller and larger flap areas, axle 224 configured
to urge baffle 223 into the closed condition against stop 225. Stop
225 is at the same level and diameterically opposite to baffle 223,
so that when stopped from rotating radially outward, baffle 223 is
straight across or disposed perpendicularly to the imposed column
of fluid. When flow through the line is antegrade as shown in FIG.
62 panel A, the fluid column must pass the perforations in the
fluid resistor baffle to flow through or lift the piston-plunger of
a syringe. When the flow is reversed to aspirate as depicted in
FIG. 62 panel B, the larger or flap side of the valve or baffle is
pulled adaxially toward the long axis of the barrel-assembly or
radial projection catheter, allowing fluid to flow unimpeded
through the working face and body of the tool-insert and into the
fluid supply line.
[3690] If fitted within a frame, the frame can serve as a shape
adapter, so that provided it has a round frame, a square valve can
be fitted into a round base-hole or base-plug, for example. That
is, in the closed position, the baffle constrains fluid entering
through the base-hole or base-plug with the design passage and
lifting pressure to pass through its perforations lifting the
tool-insert or driving the fluid syringe emitter outward causing
its contents to be expelled. Reversal of flow through the fluid
line, that is, retrograde or aspirative flow draws the side of the
baffle with greater area downward but only to an angle such that
re-reversal of the flow quickly rotates the hinged side up against
the stop reinstating fluid resistance. Compared to the equivalent
emitting tool-insert when not prefilled, the initial discharge will
be somewhat more resistant due to the additional resistance posed
by the ejectant or injectant.
[3691] During outflow, or outward (emissive) flow, the side of the
disk with greater area is pushed so that the disk spans across the
fluid path through the tool-insert to act as a fluid resistor,
while during inflow, the stronger flow against the larger portion
of the disk causes the disk to align with the flow and thus not
become clogged by aspirated debris. The sum cross-sectional area of
the perforations in any one injection or ejection tool-insert
determine the viscosity range, hence, suitability of that
tool-insert for use with a given fluid. A prefilled syringe type
fluid tool-insert must be empty before it can be used to aspirate.
Due to the lesser force of aspiration, the break seal, cap, or
stopper used to retain and preserve the sterility of syringe
contents is eliminated during syringe discharge before aspiration
commences.
[3692] Preferably, the base of the tool-insert itself is glued to
the upper surface of the lift-platform so as to separate at the
desired pressure. Alternatively, a one-way rupture film or
push-through cap or stopper over the internal or external opening
of the base-plug can be used. A film should be thick and a plug
resistive enough to allow an increase in line pressure sufficient
to empty the forward syringe section of the tool-insert before
yielding without clogging the syringe outlet. Such a one-way
rupture film when thinner or push through plug when thicker can
consist of a dried sugar, methylcellulose, or hypromellose
(hydroxypropyl methylcellulose) with polyethylene glycol 400, or
some mixture thereof, for example. The exact formulation of the cap
depends upon the ambient temperature in which the tool-insert is
used. Reciprocally, the composition of the cap can be set to hold
fast until a certain temperature is reached.
[3693] An ejector can also deliver heated or chilled gas or liquid
for ablative application to the lumen wall, alternative means for
thermal or cryogenic treatment consisting of delivery through
barrel-tubes or cooling catheters as addressed in the section above
entitled Rapid Cooling Catheter and Cooling Capillary Catheter for
Cooling Heated Turret-motor, Electrically Operated Radial
Projection Unit Lifting Thermal Expansion Wire, and Recovery
Magnets, or heating by means of heat-windows, as addressed in the
section above entitled Thermal Conduction Windows (Heat-windows)
and Insulation of the Muzzle-head Body in Thermal Ablation or
Thermal Angioplasty Minimally or Fully (Independently Usable)
Capable Barrel-assemblies. At higher line pressures, an ejector
functions as an irrigator with antegrade flow or an aspirator with
retrograde flow. The antegrade delivery of a chilling or heated gas
with antegrade or irrigative flow can be used to ablate tissue.
[3694] An alternative method for obtaining local cooling (or
heating) is a Peltier device, based upon the thermoelectric effect
(see, for example, Ge, Z. H., Song, D., Chong, X., Zheng, F., Jin,
L., and 6 others 2017. "Boosting the Thermoelectric Performance of
(Na,K)-Codoped Polycrystalline SnSe by Synergistic Tailoring of the
Band Structure and Atomic-Scale Defect Phonon Scattering," Journal
of the American Chemical Society 139(28):9714-9720; Lin, C., Cheng,
W., Guo, Z., Chai, G., and Zhang, H. 2017. "Exceptional
Thermoelectric Performance of a "Star-like" SnSe Nanotube with
Ultra-low Thermal Conductivity and a High Power Factor," Physical
Chemistry Chemical Physics 19(34):23247-23253; Rowe, Zhao, D.,
Ning, J., Wu, D., and Zuo, M. 2016. "Enhanced Thermoelectric
Performance of Cu.sub.2SnSe.sub.3-Based Composites Incorporated
with Nano-Fullerene," Materials (Basel) 9(8). pii: E629; Merrill,
D. R., Moore, D. B., Bauers, S. R., Falmbigl, M., and Johnson, D.
C. 2015. "Misfit Layer Compounds and Ferecrystals: Model Systems
for Thermoelectric Nanocomposites,` Materials (Basel)
8(4):2000-2029; D. M. 2005. Thermoelectrics Handbook: Macro to
Nano, Boca Raton, Fla.: Chemical Rubber Company/Taylor and Francis;
DiSalvo, F. J. 1999. "Thermoelectric Cooling and Power Generation,"
Science 285(5428):703-706; Ioffe, A. F 1957. Semiconductor
Thermoelements and Thermoelectric Cooling. London, England:
Infosearch). Peltier devices can also be used in heating devices
addressed herein, such as heating windows.
[3695] With retrograde flow, a vacuum can be induced and debris
carried away by circulating a liquid or a gas through the fluid
circuit. During aspiration, the vacuum is created to the inlet
chamber 194 side of outlet chamber 195 roof fluid resistance plate
or baffle 199. Debris aspirated by this tool-insert is moved
retrogradely (pumpward) until the next roof-plate is encountered
where the particulates will eventually accumulate and necessitate
flushing once clogged.
[3696] To cause a pressure increase that forces fluid up base-plug
opening 201 during antegrade or tool-insert lifting and/or
actuation flow and allow aspiration so that debris can freely move
past roof-plate 199 during retrograde flow, perforated outlet
chamber fluid resistor roof-plate 199 is hinged for up and down
rotation to the fluid chamber 195 wall, chamber outlet chamber 195
being the outlet chamber with fluid in the supply line moving
antegrade from left to right and the tool-insert engaged within the
projection unit as depicted in FIGS. 59, 60, and 63. Since
roof-plate 199 would be difficult to access and exchange with
others having different slit or perforation cross sectional areas,
barrel-assembly or radial projection catheter for use with fluids
covering a wide range of viscosity incorporate separate fluid
circuits with projection units.
[3697] Increasing the line pressure at the pump affords some
latitude in viscosity with a given roof-plate 199, but quickly
results in excessive pressure of ejection, aspiration, and
breakage. The use of a. 1. A liquid or 2. Mixture of liquids, or b.
1. A gas or b. Mixture of gases followed by a liquid or mixture of
liquids, is preferred as it flushes the circuit reducing the risk
of clogging. With small particulates, this may allow continued use
of a fluid circuit in either direction. A fluid injector can also
function as an irrigator; however, unlike an injection syringe that
collapses to a retracted position within the tool-insert once
discharged, a fluid injector can discharge only when projected.
Since this can result in injury to the lumen wall, single-orifice
fluid tool-inserts are not used as irrigators unless integrated
into a cutting (shaving or abrading working faced) tools.
[3698] Fluid injection needles are projected in use and unless
integrated into working faces, not used as aspirators; the
application of suction to assist needle penetration draws in
debris, is unnecessary, and most often ineffective. The general
structure of fluidically operated units is set forth above in the
introductory section entitled Radial Projection Units. In FIGS. 59,
60, and 63, partition (dividing wall, separator) 188, comprising
floor portion 190, aperture 193 closable in opposite directions by
spring loaded passive flapper valves or stoppers 191 and 192, and
roof portion 189 into which strip-spring 187 is secured down by
fastener 198 separates fluid inlet chamber 194 from fluid outlet
chamber 195. Outlet chamber 195 is roofed over by perforated
roof-plate 199 Since the direction of fluid flow through supply
line 203 is reversible, and a fluid tool-insert can be rotated to
face in the opposite direction, inlet chamber 194 is not roofed
over by a roof-plate.
[3699] Lift-platform retracting strip-spring 187 is fastened at its
ends to the undersides of lift-platform 176. Roof-plate 199,
covering outlet chamber 195, is cut out to clear strip-spring 187
at its center where strip-spring 187 is fastened to the top portion
of chamber partition 188. Compound fluidic-mechanical flow-through
tool-insert, to include ejector irrigator aspirators and injectors
may present an additional resistance, consisting of an entry
elastomeric membrane valve or strip-spring fluid valve or regulator
covering the external or internal opening into the plug at the base
of the tool-insert or a damper type valve as shown separately in
FIG. 62. When the pressure in inlet chamber 194 exceeds the
resistance posed by strip-spring 187, lift-platform 176, which is
constrained to rectilinear or nontilted elevation or lift radially
outward, and descent is forced radially outward (upward as
shown).
[3700] Roof-plate 199 over outlet chamber 195 is of a flow through
rate specified to resist flow sufficiently as as not only to
increase the pressure in the line to that required to raise
lift-platform 176. Pressure greater than this will pass the entry
elastomeric membrane slit valve or strip-spring valve in the base
of the tool-insert or a damper type valve as shown separately in
FIG.62. Antegrade pressure thus causes fluid in the line to flow up
through and out the tool-insert into the lumen or its wall as well
as through outlet chamber roof-plate 199, while regrogade pressure
on reversing the pump has the opposite effect. Specifically, pump
reversal produces a partial vacuum on the near (pumpward) side of
the line and thus draws fluid from the lumen into the tool-insert
as well as through the membrane or damper type valve as shown
separately in FIG. 62 in the line.
[3701] Outlet elastomeric roof-plate 199 must present sufficient
resistance to flow to divide the flow between the lift-platform 176
and inlet chamber 194; that is, sufficient resistance to
flow-through that lift-platform 176 with emitter or flow-through
tool-insert such as an ejector or injector inserted is forced
upward but sufficient flow continues past outlet chamber 195
roof-plate 199 that flow continues to the next unit. It must thus
offset the combined resistances posed by strip-spring 187 and if
present, the inlet roof membrane or damper type valve as shown
separately in FIG. 62, as well as any optional elastomeric membrane
or strip-spring valves present, whether inside the tool-insert plug
or affixed to the roof of inlet chamber 194. Pump and circulation
reversal then have the effect of posing less resistance to the
withdrawal of fluid through the base entry and discharge portal or
passageway 220 affording aspirating action.
[3702] Placing a mirror image or antipodal flapper valve on the
antegrade outlet chamber 195 allows tool-inserts to be bypassed at
subaspirating pressures. The proper balance between the relative
resistances posed by the fluid path up through and out of the fluid
ejection tool-insert, which includes the viscosity of the fluid in
the tool-insert and the area of the apertures through which the
fluid is emitted, and outlet roof cover roof-plate 199 allows some
fluid to flow through roof cover roof-plate 199 thus allowing the
passage of fluid to the next unit in the circuit. The higher
resistance to fluid flow-through outlet chamber roof-plate fluid
resistor valve 199 and plug entry or mouth roof-plate 199 causes
fluid to flow against the less resistance up into tool-insert 184.
Partition 188 separating inlet chamber 194 from outlet chamber 195
contains aperture 193 that allows fluid to bypass the unit without
raising lift-shaft 182.
[3703] Facing fluid chamber partition 188 bypass passage 193 within
inlet chamber 194 at either side (which represent either the inlet
or outlet depending upon the direction of flow as antegrade and
ejecting or retrograde and aspirating as set at the pump) are
flapper valves 191 and 192. Flapper valves 191 and 192 consist of
hemispherical or cup-shaped stoppers of any nonallergenic and
surfactant free pliant or rubber-like material supported at the
distal ends of elastomeric or metal wire or band spring-arms
positioned with the convexity directed toward so as to seal or
obturate the entry into partition bypass opening 193 at their
respective sides. Thus, when the antegrade fluid pressure exceeds
the resistance posed by spring-arm supported valve 191, for
example, valve 191 is driven against and seals the entry into
partition 188 bypass passage 193.
[3704] In fluid operated radial projection systems that must allow
a wide range of fluid pressures, the lifting and fluid delivery
portion (at the bottom in FIGS. 59, 60, and 63), otherwise built
into the barrel-assembly muzzle-head or radial projection catheter
for nonduplicative economy, is a part of the tool-insert. With such
a bypass, fluid continues to flow past the unit until the line
pressure exceeds the resistance of the flapper valve spring-arm of
this particular projection unit, whereupon flapper valve 191 closes
causing fluid to rise up over partition 188 lifting lift-platform
176. Once flapper valve 191 closes, the pressure acts against the
bottom of lift-platform 176 forcing strip-spring valve 187 to flex,
allowing fluid to pass and raise lift-platform 176.
[3705] An inert bit with cutting face or syringe tool-insert is
lifted into working position, while a tool-insert with base-plug
strip-spring valve poses a second tool-insert internal resistance
to the passage of fluid from the line through the tool-insert. A
bypass serves two major purposes in allowing a. Fluid to be moved
past units at low pressure at any time prior to use, thus
eliminating the pump outlet to inlet chamber fluid transit time,
reducing unit response time, and b. Units provided with less
stiffly sprung (weaker) bypass flappers and lift-platform
strip-springs farther downstream to be actuated before units having
stiffer springing more proximate to the pump outlet so that
tool-inserts with lift-platforms that are bypassed are not raised
much less pass through fluid.
[3706] Provided the barrel-assembly or dedicated radial projection
unit catheter is free of bending, such as with the aid of an
assistant during manual use or through the use of a linear
positioning stage and forward drive and sag leveling and
stabilizing device under motorized control, bypass makes it
possible to start circulation through the circuit at pressures
lower than required to close the weakest flapper in the circuit
prior to entry. Comparing the pressure control gauge reading to the
actuation of the units allows the pressure response of each unit to
be tested prior to use. With the line pressure further increased,
the fluid system ejector shown in FIGS. 52c, 58, and 63 serve as
irrigators, and at high pressure as a miniature water or other
liquid jets or tiny pressure washers.
[3707] Because the addition of shaving edges or an abrasive texture
to the working face requires projection during and retraction
following use as does an injection needle, the integration of
irrigation into tool-inserts that include cutting faces requires a
telescoping tool-insert (not shown) for use in injectors. Lifted at
pressures lower than used for washing, these cannot be used as
irrigators while retracted. Neighboring fluid ejectors are used for
washing when cutting head tool-inserts are retracted. Fluidic
tool-inserts use a plug-in base not only for mechanical connection
to the upper surface of the lift-platform by insertion in a socket
but also for fluidic connection to the fluidic circuit. When
present, fluid tool-insert plugs are open at the bottom. Only fluid
tool-inserts can directly transmit the fluid in the pipeline to the
lumen or inject this fluid into the lumen wall.
[3708] An electrical/fluid system-neutral radial projection unit
syringe injection or ejection tool-insert, such as that shown
inserted in an electrically operated radial projection unit in FIG.
55, is self-contained, using the lifting mechanism at the base of
the lift-shaft only for lifting into and retraction from the
working position. Such a syringe tool-insert has the advantage of
usability in any radial projection unit of matching dimensions but
has the disadvantage of a finite volume of the therapeutic fluid.
By contrast, the fluid operated counterpart shown in FIG. 63 can
feed through fluid from supply line 203, in which case the line
fluid is both the hydraulic and therapeutic fluid, and the syringe
can contain an initial preload of a different or pre-treatment
therapeutic fluid.
[3709] Fluidic tool-inserts can incorporate fluid resistor plate,
membrane, and spring valves to achieve lift internally, allowing
adjustment in the relative timing of fluid ejection or injection by
each tool-insert along the fluid circuit. When this tool-insert is
provided with a strip-spring covered bottom entry hatch, it can
still be used in either type unit to discharge its content. In an
electrically operated unit, the spring hatch is not used, and only
the prefilled load is available. However, when inserted in a fluid
operated radial projection unit, once its prefilled load has been
emitted, the fluid ejector can pass through fluid from the line. A
prefill (preload, initial load) of the same or another drug or
therapeutic substance than that to follow from the line can be
ejected ahead of that in the fluid supply line.
[3710] The fluid from the line can be used to dilute, irrigate,
activate or be activated by, or act in combination with the initial
load. A fluid operated injection syringe is of like structure but
releases its content through an injection needle. Raising the line
pressure above the lifting pressure forces lift-platform 176 lift
away from strip-spring 187 that at lower pressures obturates the
entry up into base-plug space 220, exposing the opening into the
base-plug. The initial load or fluid preloaded in the emitter then
flows through the tool-insert and out the working face. Further
raising the line pressure then allows fluid to pass slit membrane
damper fluid resistor ejection-aspiration switching valve as shown
in FIG. 62, positioned within base-plug space 220 and spring loaded
bottom hatch valve 221.
[3711] The fluid in the line then forces its way up through the
tool-insert to be emitted through the pores in the working face,
which are sealed with a fine film to retain the prefill prior to
use. In fluid tool-inserts with a base-plug, syringe plunger 197
has a short projection on its undersurface that is the positive or
male complement to base-plug space 220 in lift-platform 176, which
latter receives this projection as the receptacle or female
complement thereto. Insertion of this base-plug into cavity 220 to
seize therein by frictional retention is accomplished with less
force than drives plunger-plate upwards expelling the contents of
chamber 203 through injection needle or hypotube 209. The outer
surfaces of the syringe tool-insert body closely fit within
lift-shaft 182, but lined with a low friction polymer such as a
fluoropolymer, allow the lifting or expulsion driving means to
freely raise and lower the tool-insert.
[3712] Electrical and fluid systems use radial projection unit and
tool-inserts made to standardized incremental dimensions as sets
with as much commonality of componentry as possible. While the
conformation of electrical/fluid system neutral injection and
ejection syringe tool-inserts as shown much limits the finite
volume of fluid such a closed or self-contained syringe can
deliver, the absolute volume can be considerably increased when
consecutive radial projection units are separated by removable
inserts so that the syringe tool-insert can span over two or more
projection units. Expanding the syringe in muzzle-heads and radial
projection catheters affording slight depth in the other two
dimensions allows the delivery of a larger dose than might two
separate syringes divided by a gap or gaps.
[3713] In electrical circuits with built in delays between
consecutive units and in fluid operated circuits, the time delay
between consecutive projection units cannot cause syringe plunger
197 to tilt and seize within syringe barrel 196, because these are
faced if not made of a low friction polymer, and plunger 197 is
constrained and forcibly aligned within syringe barrel 196. The
height of the contents is equal to the excursion afforded by the
lifting means, and once the lifting or expulsive force is removed,
strip-spring 187 retracts the syringe pulling needle 209 within
lift-shaft 182, preventing incisions upon resumption of
transluminal or rotatory movement. Increasing the volume of
injectant therefore requires a unit of longer radial excursion or
larger cross section. Numerous configurative, textural, and
materials means are well known for enhancing the frictional
retention of a base-plug if present within cavity 220.
[3714] Provided the valving internal to the syringe tool-insert are
gauged to respond at the pressures applied, the cross sectional
shape and area of the base-plug and cavity 220 need not match that
of the fluid supply line. Rotatable or swing-out hold-down or
retaining arms 186 act as stops to the excursion radially outwards
of the syringe. It will now be seen that lift-platform 176 first
slides injection or syringe tool-insert radially outwards against
the restorative force of strip-spring 187 until retaining arms or
stops 186 prevent further outward movement. Needle 209 now
extending beyond the surface of the muzzle-head, continued force
against plunger--197 forces the contents of injection or syringe
tool-insert 184 as indicated in FIG. 54 out through needle 209.
Discontinuation of the lifting force frees strip-spring 187 to
retract needle 209.
[3715] VII2g(3)(e)(vii). Use of Flow-Reversible Tool-Inserts for
Microaspiration
[3716] Barrel-assemblies with a fluid side-socket allow connection
of a fluid radial projection system to an aspiration pump even with
the barrel-assembly engaged in the airgun during ballistic
discharge. However, since the barrel-assembly is seldom if ever
engaged in the airgun except during ballistic discharge, the
proximal end of the barrel-assembly is accessible for connecting
barrel-tubes to an aspiration pump. Flow-through tool-inserts,
barrel-tubes, and an unoccupied central channel or passageway in a
combination-form barrel-assembly can be connected to an aspiration
pump and used to aspirate. The hinged and perforated fluid unit
outlet chamber cover and opening through the chamber partition that
allow retrograde flow are addressed above in the section entitled
Radial Projection Units. Thrombectomy router/aspirators that remove
thrombus and plaque by rotary cutting and the resulting debris by
aspiration are common.
[3717] Rotary devices can be effective for the removal of thrombus
and radially symmetrical plaque; however, radially indiscriminate,
used to treat eccentric lesions; a microrouter can grate on, gouge,
and even perforate a healthy portion of the lumen wall. This
eventuality is usually protected against by using a router
significantly undersized in diameter, resulting in the removal of
the more medially protrusive, or cap-ward, portion of the plaque
while allowing more abluminal or radially distant portions to
remain with cut surface exposed. A critical need to restore flow
can be satisfied, and the placement of an endoluminal stent can
extend this patency, but restenosis is usually inevitable.
Side-looking aspiration tool-inserts and barrel-tubes allow not
just the aspiration of matter freed by cutting or abrading tools,
but with suitable imaging and contrast markings on the apparatus,
the direct, radially oriented removal of soft plaque and diseased
tissue by microaspiration.
[3718] Whether used to remove debris released by angioplasty,
deliberately remove material from the surface of the luman wall, or
ablate diseased tissue, the force of aspiration must be appropriate
for the purpose and closely controlled. The optimal force must be
determined by spot-testing the actual tissue to be removed within a
range that has been preestablished on the basis of experience with
similar tissue. The aspiration of fluid with particles suspended
will be limited by the rate at which the apertures in the lift
mechanism become clogged. However, subject to the need to avoid
obstruction in the treatment of blood vessels, clogging can be
alleviated without the need to withdraw. This is accomplished by
retrograde flushing of the line or lines under low pressure with
sodium hypochlorite, then with water at higher pressure before
resuming.
[3719] VII2g(3)(e)(viii). Temperature Control in Fluid (Piped)
Tool-Inserts
[3720] Using a thermally insulated electrical syringe tool-insert,
a small volume of fluid can be preheated and ejected into the lumen
or injected into the lumen wall at the treatment site. While this
capability will often have utility, the total volume of medication
that can be preheated with prefilled electrical syringes is
limited. Large barrel-assemblies and special radial projection
catheters for use in the gastrointestinal tract, trachea, or
bronchi where temperature is seldom critical will usually have
sufficient clearance or recession from the lumen to initiate the
heating of thermally insulated syringes or retracted hot-plate
tool-inserts prior to application.
[3721] Moreover, for intermittent use, hot-plate type tool-inserts
must directly interface with the lumen and cannot be thermally
insulated over the working face at a reasonable cost. Especially in
blood vessels, wherein temperature can be critical, the caliber of
a vessel may be too restrictive to admit a barrel-assembly or
special catheter having a diameter large enough to allow a
hot-plate type tool-insert to be adequately retracted during
preheating. Thermoplasty or melting implanted protein solder, for
example, which use hot-plate type tool-inserts, are safer and more
efficient when the operative temperature can be achieved and
quickly reverted from at the treatment site.
[3722] Electrically heated tool-inserts require microcontroller
regulation to pass through thrombogenic temperatures quickly and
incapable of chilling, necessitate the use of a cooling catheter
for quick return to body temperature. By contrast, a fluidic
tool-inserts can chill as well as heat, and do either quickly by
passing fluid through it that has already been brought to the
target temperature at a location remote from the treatment site.
fluid system also allows switching between water or any other fluid
medication or therapeutic substance that has been preheated or
prechilled to a target temperature and water, for example, to
quickly return the tool-insert to body temperature.
[3723] A fully internalized fluid reservoir of a size that will fit
into the power and control housing, or battery-pack hand-grip part
of an ablation or ablation and angioplasty-capable barrel-assembly
or special radial projection catheter is likely to be too limited
in fluid volume, and while heatable, is seldom chillable within the
size constraints imposed without external connection. A
Joule-Thomson microrefrigerator, for example, requires three
connection lines. Interchangeable cartridge-configured fluid
reservoirs can be inserted into the power and control housing in an
ablation or ablation and angioplasty-capable barrel-assembly or
special radial projection catheter with the fluid already heated or
chilled to compensate for the drop or rise in temperature due to
time delay and transmission line losses until the treatment site is
reached.
[3724] This affords somewhat more freedom of movement than does
connection to remote temperature controlled reservoirs through
switchable hosing and a fluid side-socket. However, external
connection removes limitations in number, volume, and temperature
of different fluids that can be delivered. Chilled fluids in
particular are best pumped from external refrigerated tanks with
the temperature adjusted to compensate for delivery through the
line to the treatment site. Fluid that is not itself medication for
injection or ejection but is used only to control tool-insert
temperature and/or to raise fluid unit lift-platforms is
recirculated, hence not depleted. The heating and pumping of the
fluid can therefore be small enough to incorporate within the
apparatus.
[3725] VII2g(3)(e)(ix). Doublet Irrigator-Aspirator Tool-Inserts,
or Point-Washers
[3726] The use of separate emitter-irrigator-aspirator tool-inserts
to flow fluid over the lumen wall is addressed above in the section
entitled Radial Projection Units. By contrast, a doublet consists
of two identical or similar tool-inserts unitized in back to back
relation intended to flow water or a therapeutic fluid over a focal
treatment site. Back to back irrigator-aspirators, or
point-washers, directly target and quickly aspirate water or a
therapeutic fluid from a short segment of the lumen wall. This
allows, for example, exposing the wall to a therapeutic substance
or a thermoplastied segment to be returned to body temperature more
quickly than if the fluid were released and aspirated over a larger
area. The tool-inserts in a doublet differ from separate
emitter-aspirators in having thicker face plates with perforations
that are angled to aim the ejectant toward the aspirator and
sharing a common inner wall.
[3727] Other doublets can include, for example, a cutting
tool-insert and an aspirator. Particulate size, the rate at which
the aspirator clogs, and time required to flush the line must be
taken into account. The recovery of debris is improved as the
number of aspirators in the same and different fluid circuits is
increased. Since the internal structure of each tool-insert in the
pair or doublet is anteroposteriorly asymmetrical to perform as an
emitter-irrigator or as an aspirator depending upon the direction
of flow through the fluid circuit, doublets in the same circuit
will emit or irrigate or aspirate depending upon their
anteroposterior anteroretrograde orientation in the circuit.
Reversing this orientation thus reverses which subtool in the pair
or doublet acts as the emitter and which acts as the aspirator and
does not affect the function of the doublet as a unit.
[3728] Therefore, with one or a few doublets exposed to debris,
clogging can be forestalled by periodically reversing the direction
of flow through the fluid line to carry debris in the doublets to a
filter in the power and control housing. Since a heated filter for
burning the debris would raise the temperature of the line fluid,
the filter is incorporated into the reservoir refill cartridges.
When anteroposteriorly oriented alike, doublets in separate
circuits wherein the line fluid is pumped in opposite directions
perform the same action. Typically, the barrel-assembly will be
halted to use an injection tool-insert, and washing action commence
upon resumption of transluminal movement. Reversal in transluminal
direction affects neither the direction of fluid flow through the
fluid circuit nor the directions of irrigative and aspirative
function of the doublet.
[3729] Reversing this orientation thus reverses the action, whereas
tool-inserts placed in separate circuits of flowing in opposite
directions perform the same action when anteroposteriorly oriented
alike. Back to back irrigator-aspirators, or point-washers, direct
at and quickly aspirate fluid from a small segment of the lumen
wall, allowing, for example, exposure to a therapeutic substance or
a thermoplastied segment to be returned to body temperature more
quickly than if the fluid were released and aspirated over a larger
distance. Typically, the barrel-assembly will be halted to use an
injection tool-insert, and washing action commence upon resumption
of transluminal movement.
[3730] Reversal in transluminal direction affects neither the
direction of fluid flow through the fluid circuit nor the
directions of irrigative and aspirative function of the paired or
doublet tool-insert. Reversal of flow through the fluid circuit
only reverses which unit in the doublet functions as the emitter or
aspirator, which has no medical significance. Consecutively
positioned doublets connected to separate circuits can
intermittently or continuously wash the lumen wall with water or
different therapeutic fluids, and these can be changed
midprocedurally by connection to different reservoirs or radial
projection catheter power and control housing and hand grip inmate
reservoir refill cartridges. Reversing the direction of flow
through doublets fore and aft of an injector, for example, will not
affect the therapeutic action whether the doublets are connected to
the same or different circuits.
[3731] VII2g(3)(e)(x). Elimination of Gases from Fluid Radial
Projection Unit Lines
[3732] FIG. 58 shows a simplified diagrammatic view of a fluid or
piped circuit where the pump is built into the power and control
housing, and is analogous to the battery used to power electrical
units as shown in FIG. 57. The liquid in the closed circuit that
courses through the barrel-catheter to the units may constitute the
substance to be delivered or represent its solvent or medium, such
as water. In the vascular tree, no significant amount of gas should
enter the bloodstream. The small lumen diameter of most blood
vessels demands that further reduction in the diameter of pipes and
service-catheters be avoided, effectively eliminating the use of
double lumen tubing, for example.
[3733] Once the circuit has been filled, or charged with the liquid
medication or medium with the column from the reservoir continuous,
the entry of air into the line is a concern when different liquid
substances must be switched from one source reservoir to another.
Delivery of the fluid in the circuit is directly analogous to
infusion through an intravenous drip chamber, which serves to
eliminate any air, an infusion pump and rapid infuser used when
necessary to increase the rate of delivery through any of several
type well established connections. Metered ejection in measured
doses per treatment site can be accomplished with a metered
pump.
[3734] VII2g(3)(f). Radial Projection Unit Control and Control
Panels, Elecrical and Fluidic or Piped
[3735] FIG. 79 shows a control panel for a barrel-assembly or
radial projection catheter which incorporates only electrically
operated components for performing an angioplasty. Duplicate
controls not mounted to the apparatus controlled may be provided
for use by an assistant; however, to minimize operator error,
interventional airgun, angioplasty, and ablation control panels are
mounted to the respective apparatus the given panel controls. In a
duplex or bipartite type barrel-assembly such as shown in FIG. 71,
only the electrically controlled angioplasty components
incorporated into the barrel-assembly proper at b. are controlled
from control panel 163, and only the angioplasty components
contained within the ensheathing radial projection catheter at a.
are controlled from control panel 164.
[3736] That is, onboard control panel 163 includes only the
controls for the power and control housing to which it is mounted,
so that the apportionment of controls between the power and control
housings reflects the apportionment of capabilities between the
components of the duplex. Most often, the barrel-assembly without
the ensheating radial projection catheter will be at least
minimally angioplasty-capable, with turret-motor and nose heat
windows or laser for preemptory thermoplasty capability.
Combination-form barrel-assemblies generally accept original
equipment manufacturer produced cabled devices such as lasers and
angioscopes supplied and used with a dedicated control console so
that these controls may be separate and require the use of an
assistant.
[3737] Self-contained ablation or angioplasty-capable
barrel-assemblies and radial projection catheters can incorporate
different components, so that combinations of these to comprise
duplex barrel-assemblies will variously apportion the controls for
the components contained within each between the respective power
and control housing control panels. In barrel-assemblies and radial
projecton catheters for use in narrower ductus, this diversity is
constrained not only due to the lack of space but the need for
trackability. To optimize trackability in a duplex barrel-assembly,
the unensheathed barrel-assembly proper or primary is minimized in
diameter. This limits it to few, usually not more than four,
electrical circuits to control the turret-motor, recovery
electromagnets, and any radial projection units.
[3738] In barrel-assemblies for use in lumina that are less
restrictive, the primary can include electrically and fluid
controlled heat-windows and tool-inserts, and tool-inserts of
either type may incorporate internal functions such as warming the
contents of an injection syringe, which require additional
circuits. Accordingly, the specific controls and the apportionment
of these in ablation or angioplasty control panels of different
barrel-assemblies and radial projection catheters vary
considerably. For this reason, the control panel shown in FIG. 79
can be no more than exemplary. In a fluid circuit, current is used
to control the electrohydraulic or electropneumatic control valve
in each circuit fluid supply or pipe line.
[3739] The absolute distance of travel up and down and thus
extension of the tool tip face beyond the outer surface of the
muzzle-head is generally proportional to the diameter of the
muzzle-head, which limits the depth of the radial projection unit
lift-shaft 182. Within this gamut, the distance lift-platform 176
is raised is controlled by adjusting the electrical or fluid
current. Upon the removal of current, thermal expansion wire 177
contracts to its dimensions at room temperature. Insertion of a
chilled rod or cooling catheter down the adjacent barrel-tube will
hasten retraction of the tool-insert. With a fluid circuit, a fluid
control valve would shut off fluid flow causing lift-platform 176
to descend. While the control knobs are collocated on the control
panel, independently controllable fluid circuits employ independent
pumps.
[3740] Whether raised electrically or by fluid, retraction of
lift-platform 176 is allowed by removal of the lifting current but
effected by the downward urging of strip-spring 187, which prevents
dissections by retracting the working face of tool-insert 184 to a
position beneath the outer surface of the radial projection unit.
When energized, thermal expansion wire 177 raises tool holding and
lift-platform 176 to the top of lift-shaft 182 causing the working
face of tool-insert 184 in FIG. 54 to radially extend beyond the
surface of the muzzle-head. In a barrel-assembly for use in the
vascular tree, the risk of embolization without the trap-filter
deployed is reduced by limiting the excursion of the tool tip faces
or upper edges of the tool-inserts beyond the outer surface of the
muzzle-head to generally no more than 1.5 millimeters.
[3741] Incorporating a highly miniaturized electric scissors lift
linkage, as described above in the section entitled Extended
Projection Scissors Lift-platform Mechanism, allows the tip or
working end of the tool-insert to be extended farther outwards. The
trap-filter is authomatically deployed upon energization of a
radial projection unit even when no such height extension means is
present. In piped or fluid operated circuits, elevation of
lift-platform 176 requires no separate control but occurs on
initiating fluid flow. If circulated at room temperature, the fluid
is used to effect projection, such as of a closed-face or blank
tool-insert for the purpose of nudging the muzzle-head in the
opposite direction or to allow the tool face to be swept over the
lumen wall.
[3742] The fluid can be chilled or heated for a number of purposes,
to include accelerating or decelerating endogenous or introduced
chemical action or, in an artery, for example, to ablate plaque.
The delivery of solid solder miniballs lumen intraductally, for
example, necessitates heating in order to denature the solder. The
miniball is delivered through a barrel-tube, and as the muzzle
continues distad, the radial projection unit moves behind to heat
the miniball, which process can proceed continuously. Within the
vascular tree, the projection of heat or cold is by applying a
liquid to the rear of a blank metallic face-plate of high thermal
conductivity. In other type ductus, the plate may be perforated to
allow heated or chilled gas to be streamed over the lumen wall.
[3743] Since the duration of the procedure is a prime consideration
and elevated ablative or abrasive type tool-inserts will preclude
continued movement of the barrel-assembly until fully retracted
(seated, stowed), a means for contracting the thermal expansion
wire quickly once current is stopped is essential. To this end,
strip-spring 187 assures that the recession (retraction, lowering)
of lift-platform 176 is not limited in speed to the time it would
take for expansion wire 177 to contract by passive cooling on
deenergization, and thus eliminates the need to insert a cooling
catheter. Piped units that are lifted coincident to fluid flow are
also spring loaded for automatic return this way. Since
temperatures above and below 90 degrees centigrade, which is
effective for thermoplasty, are thrombogenic, the turret-motor and
recovery electromagnets should heat the lumen wall through their
housings to a temperature of 90 degrees centigrade with minimal
rise and drop-off times.
[3744] Provided it is temperature isolated from the surface of the
barrel-assembly except at the treatment face-plate, a fluid,
because it can be preheated remotely from the muzzle-head and not
have to build up or drop back in temperature right at the treatment
site as must an electrically heated element, affords better control
over temperature, which factor recommends piped radial projection
units. The barrel-assembly will be capable of discharge and
temperature ablation or angioplasty in alternation; however, the
interval to allow dimensional stabilization will vary according to
the materials and dimensions of the barrel-assembly. This interval
must be specified and heeded.
[3745] In an electrical unit, the 90 degree-equivalent current used
must be controlled to achieve this temperature, maintain it during
use, then revert to body temperature as quickly as possible
recommending microprocessor control over the current in each
circuit. In both electrical and fluidic units, a spatial
temperature gradient along the surface of the muzzle-head is
prevented by placing insulation about at the margin of the intended
lumen contact area. The 90 degree centigrade-equivalent limit
current for the turret-motor windings and tractive electromagnets
does not apply to thermal expansion wire 177, which is in an
independent circuit and substantially temperature-isolated from the
lumen wall by the intrinsic insulation value of the polymer
material of or added lining in lift-shaft 182 and the thermal
expansion wire 177 insulation.
[3746] The resultant ability to use a larger diameter expansion
wire 177 with materials that exhibit a high thermal coefficient of
expansion and melting point far higher than the temperature
required, yield a high wire breakdown temperature and thus allow
higher temperatures and degrees of wire expansion, hence, degrees
of outward extension of lift-platform 176 for the tiny space
available. In thermal ablation or ablation and angioplasty-capable
and combination-form barrel-assemblies, the onboard electrical
components draw current from the inmate battery in the hand-grip,
radial projection units wired in series controlled together.
Electrical components include those end-purpose at the treatment
site, and those supporting piped units (see, for example, Yu, Z.
Q., Hu, M. J., Pei, X., and Ruan, J. 2006. "Actuation and Control
of a Micro Electrohydraulic Digital Servo Valve," Journal of
Physics: Conference Series: International Symposium on
Instrumentation Science and Technology 48:264-268).
[3747] A thermal ablation or ablation and angioplasty-capable or
combination-form barrel-assembly with fully self-contained fluid
pipe circuits requires a reservoir and micropump for each circuit.
Low pulsation micropumps are currently available from many makers,
to include Micropump Division, IDEX Corporation, Vancouver, Wash.;
Cole Parmer, Vernon Hills, Ill.; TCS Micropumps Limited,
Sittingbourne, Kent; ThinXXS Microtechnology, Zweibrucken; and
Microfluidics Division, Frauenhofer Institut fur Zuverlassigkeit
and Mikrointegration, Munchen [Frauenhofer Institute for
Reliability and Microintegraton, Munich]. While inserted in the
airgun, power can be drawn from the airgun power supply. Even if
used in a coordinated manner, piped and nonpiped elements are
generally not controlled together by wiring thermal expansion wires
and fluid control valves in series.
[3748] Used in banks or groups, radial projection units can be used
to nudge the muzzle-head eccentrically within the lumen to allow
blood to pass. Unlike a balloon which dilates with radial symmetry,
radial projection units can thrust sideways in any direction which
their distribution will allow. When deflated, the balloon is,
however, less obstructive and allows more blood to pass. Except for
the upper corners, which are die-cut as rounded off at the upper
ends to prevent cutting into the lumen lining, the upper edges of
the faces and side edges are left squared. Swing out hold-down
retaining arms 186 at the sides of lift-shaft 182 are recessed from
the outer surface of the muzzle-head or radial projection
catheter.
[3749] These are swung or slid aside to remove a tool-insert and
swung over the upper edges of the lift-platform to retain it when
in the raised working position. Otherwise, tool-insert 184 could be
pulled out of lift-shaft 182 by the sideways levering forces of
resistance at the tool working end it may encounter in use. Where
an independent or barrel-assembly integral rotational atherectomy
burr or an excimer laser has eliminated hardened prominences,
radial projection unit tool-inserts can substitute for an
angioplasty balloon in eliminating the balance of plaque when less
calcified at the periphery. A supplementary plaque removal
capability is of value, because both an excimer laser or a burr
incorporated into the barrel-assembly must be centered in the
muzzle-head and no larger in diameter than such devices are when
independent.
[3750] Rotational burrs and lasers injuring the wall if used to too
great a depth, the balloon angioplasty that would ordinarily be
necessary to reduce residual plaque (atheromatous, diseased tissue)
is here replaced by a variety of radial projection unit
tool-inserts that can be used with the oscillatory mode of the
turret-motor to cut or abrade this tissue away. In a
barrel-assembly for use in the vascular tree, the risk of
embolization is reduced by limiting the excursion of the tool tip
faces or upper edges of the tool-inserts beyond the outer surface
of the muzzle-head to generally no more than 1.5 millimeters.
[3751] Provided the action does not result in obstruction of the
lumen longer than 2-3 minutes, where the muzzle-head exceeds the
lumen in diameter, the muzzle-head can itself be used to compress
soft plaque or soft plaque scraped off the lumen wall. This is done
by advancing and withdrawing the muzzle-head over the scraped area.
The incorporation of conventional means of atherectomy makes
achieving a minimally occlusive diameter more difficult, but
reduces operating time. Whether deployed during transluminal or
rotatory movement, control of the radial projection units is by
manual switching on the ablation and angioplasty onboard control
panel. With a lumen wall that is malacotic and brushes that are
harder, some tool-insert bristles could incise the lumen wall, the
operator must specifically override the default retracted condition
of the tool-insert lift-platform or platforms.
[3752] Thus, another limitation is that the radial blades should
not be deployed while the barrel-assembly is advanced or withdawn.
Described below is a switching arrangement that instantly cuts off
current to the scraper blades causing these to recede should the
barrel-assembly be urged forward or backward as well as a
circuit-breaker to stop current to the turret-motor when the set
threshold value for maximum torque is exceeded. To allow somewhat
greater depth of access into the vascular tree, when the
muzzle-head reaches a segment wherein the lumen is the same in
diameter, deployment of the radial projection unit tool-insert
side-sweeper blades allows blood to pass. To orient the blades
face- rather than edge-on to the bloodstream would further obstruct
the flow of blood past the muzzle-head.
[3753] VII2g(3)(g). Coordinated Use of Aspiration and Piped Radial
Projection Units to Remove Diseased Tissue or Obtain Tissue Samples
for Analysis
[3754] Tissue samples of greater volume and to a controllable depth
are obtained by passing a side-cutting radial projection unit
tool-insert having individual projections or `bristles` and tips of
the desired conformation as addressed below in the section entitled
Radial Projection Unit Tool-inserts. Rotational and oscillatory
action is obtained with the turret-motor or manually, and
transluminal action manually or with the aid of a linear stage,
which can also be driven to provide a vibratory effect. Scoring the
area of the lumen wall to be treated with a radial projection unit
brush tool-insert for the purpose of obtaining a tissue sample not
only furnishes the tissue on the brush for brush cytology but also
allows addtiional tissue to be recovered through aspiration.
[3755] In order to prevent the release of embolizing debris should
the fibrous cap of an atheroma be ruptured, the apparatus
automatically deploys a run-ahead trap-filter whenever a radial
projection unit is energized (actuated). The considerable
versatility in aspiration of fluids to, from, and over the
treatment site before or during a procedure made possible through
the coordinated use of supply and service-catheters, unlined
barrel-tubes, and the central canal with piped radial projection
units is addressed below under the section entitled Radial
Projection Units.
[3756] VII2g(4). Minimally Ablation and Ablation and
Angioplasty-Capable Barrel-Assembly Control Panels
[3757] A minimally ablation or ablation and angioplasty-capable
barrel-assembly is not used separately from an airgun. Such a
barrel-assembly lacks an internal power source and is meant
primarily to provide prophylactic cauterization attendant upon
discharge implantation; that is, to preclude plaque rupture by the
muzzle-head or miniballs that would result in a release of
embolizing debris. While discharge controls go to the airgun and
ablation or angioplasty controls go to the barrel-assembly, the
controls for a minimally ablation or ablation and
angioplasty-capable barrel-assembly, because it is airgun
dependent, are exceptionally mounted to the airgun. That is,
pistols and dedicated airguns meant for use with minimally ablation
or ablation and angioplasty-capable barrel-assemblies, because
these are used only while inserted in an airgun, include the
controls for ablation or angioplasty on the airgun.
[3758] An air pistol paired with an ablation or ablation and
angioplasty-capable barrel-assembly affords free manipulability as
does an ablation or ablation and angioplasty-capable
barrel-assembly when disengaged from the airgun; however, pistols
are not well suited to mounting upon a linear positional stage to
implement the discharge of implants in a close formation whether to
distribute the magnetic load, increase the dose, or both at the
treatment site. A minimally capable barrel-assembly usually takes
power from the airgun power source. If a pistol, this consists of a
battery pack in the form of a downward extension of the pistol
grip. Modified commercial air pistols for use with minimally
capable barrel-assemblies have any ablation or angioplasty controls
mounted to the side of the power and control housing, or
battery-pack grip extension, and far down enough as not to be
covered over by the hand.
[3759] Any ablation or angioplasty controls are therefore mounted
on the same control panel as the potentiometers used to control the
recovery electromagnet field strength. So long as more flexible,
finely graduated, or quickly achieved adjustment in the exit
velocity is not required, and the implants need not be placed in so
close a formation as to require placement under automatic
positional control, such a pistol and minimal ablation capability
barrel-assembly combination can achieve the ablation or angioplasty
capability of an ablation or ablation and angioplasty-capable
barrel-assembly, and in an equally compact form. However, high
density implantation over the site for treatment may be essential
to achieve the prescribed dosage level or combination of
medications with medication miniballs, or to yield a uniform and
nondissecting distribution in the magnetic tractive force.
[3760] For this reason, the combination of a dedicated
interventional airgun with an ablation or ablation and
angioplasty-capable barrel-assembly can provide the optimal
ablation or angioplasty sufficiency, and discharge precision
consistent with the greatest manipulabiity. Except for
combination-form ablation or ablation and angioplasty-capable
barrel-assemblies, a minimally ablation or ablation and
angioplasty-capable barrel-assembly can provide all of the tissue
reduction features of the capable or stage mountable configuration.
Thus, unless discharges must be placed accurately, a pistol
discharged minimally ablation or ablation and angioplasty-capable
barrel-assembly, provided it incorporates the same features as a
capable barrel-assembly, can accomplish the work of the latter at
lower cost.
[3761] However, most minimally ablation or ablation and
angioplasty-capable barrel-assemblies do not require and do not
incorporate all of the tissue reduction features of ablation or
ablation and angioplasty-capable barrel-assemblies. The control
panel of a dedicated interventional airgun for use with minimally
capable barrel-assemblies is mounted on the airgun enclosure. To
use a nose-cap heat-window, for example, these control panels
typically include controls for adjusting the current to either of
the two recovery electromagnet windings, raising and lowering
radial projection units, deploying and recovering an embolic
trap-filter, and for controlling any other features the
barrel-assembly incorporates. Generally, the controls specific to
ablation and angioplasty are mounted on barrel-assemblies with this
capability, whereas the controls for discharge positioning and
discharge are mounted on the airgun.
[3762] For convenience, controls for the one type function can be
co-located on the other device; however, a presentation that is
functionally pure, that is, which keeps the controls for either
function with the respective device, is conceived of as less
amenable to human error. In a minimally ablation or ablation and
angioplasty-capable barrel-assembly, the controls may be co-located
making it desirable to disable the distinctly implant discharge
related controls when not needed. Some original equipment
manufacturer components, such as a vortex tube based cold air gun
attached at the back of an ablation and angioplasty barrel-assembly
include their own built in controls as well. In most instances,
these will not be separable from the device itself, but the
position of the device will result in a favorable situation of the
controls.
[3763] Preclusion of a midprocedural loss in power imperative,
should the inmate battery fail, a cable to allow the direct
connection of the barrel-assembly to the airgun power supply
without the need for engagement in the airgun barrel can be
provided as a backup power source. To protect against power
failures or loss in dependability, as from harmonic distortion,
frequency variation, or voltage irregularity, the airgun includes
an uninterruptible power source. This backup notwithstanding, in an
embodiment that contains most or all of the components to be
described, the battery in the hand-grip of the barrel-assembly
should be sized to supply emergency current to power the airgun and
the barrel-assembly were the uninterruptible power source runtime
to elapse.
[3764] The controls to rotate the muzzle-head are therefore
duplicated in the barrel-assembly and the airgun. Transluminal
advancement or withdrawal with the aid of the linear positioning
table requires insertion in the airgun, so that there is no need
for a duplicate control onboard the barrel-assembly if resorted to
during an ablation or an angioplasty; however, this implies that
insertion in the airgun is true only over the relatively brief
interval required to effect more precise transluminal movement by
this means. From a mechanical standpoint, balloon cryoplasty and
thermal angioplasty differ from balloon angioplasty in that the
fluid used to inflate the balloon is chilled or heated.
[3765] Otherwise, the balloon is aligned to the lesion to be
treated by hand and inflated for the interval desired just as in
ordinary angioplasty. Not inflatable, the muzzle-head cannot use
inflation time to reduce the exposure of blood and tissue to the
thrombogenic temperatures that surround the target temperature. An
external hand-held electromagnet can be used to draw a muzzle-head
of smaller gauge than the lumen against the lesion. Along with the
blood-grooves and tunnels built into the barrel-assembly to reduce
the risk of eschemia, suitably directed `heat-windows and quick
temperature rise or drop and recovery times are important. For
isolated exposure of a distinct lesion to the heat or cold, a
muzzle-head containing a `heat-window of suitable area and shape is
used.
[3766] However, the knowledge that vulnerable plaque is not to be
equated with a localized obstructive lesion but is more likely
characteristic of the vessel over longer segments promotes a
extension for prevention approach. For this purpose, the
muzzle-head is drawn over the lumen surface at a constant
temperature at a controlled rate. To accomplish an extensive
treatment thus, a balloon must be inflated, then deflated, stepped
forward or backward by its length, reinflated, deflated, and so on.
The advantage in reduced operative time in the continuous passage
of a muzzle-head over the lumen surface is significant enough to
encourage extension for prevention.
[3767] Whether transluminal movement is by direct manipulation or a
positional mode of the linear stage, when the turret-motor is not
required for rotating the muzzle-head, use of its winding as a heat
source allows thermal, cryogenic, and/or radial projection unit
shaver, brush, or chemical discharge tool-insert angioplasty and
ballistic discharge in the same pass. This is primarily intended
for introducing absorbable medication miniballs during the
angioplasty. Ordinarily, having been brought to the position for
discharge, the barrel-assembly is stopped until the preceding
miniballs have seated or become infixed. This allows the retrieval
of any that may have been mispositioned before proceeding to the
next discharge. In a combined angioplasty and discharge, to prevent
overexposing the lumen wall to excessive ablative action, the
muzzle-head must be moved at a specific uniform rate without
pause.
[3768] The rate of passage during an ablation or an angioplasty is
thus the dominant factor to which the rate of discharge, which is
travel rate neutral, must defer. For this reason, when nonabsorbale
(medication or other chemical) miniballs are implanted, close
spacing may necessitate the initiation of successive discharges
each before that preceding it has seated. Angioplasty that combines
the use of radial projection unit tissue removing tool-inserts with
thermal or cryogenic means is not contemplated whether apart from
or in combination with discharge. Commercial controller-drivers
such as those delineated in the section above entitled Control of
Muzzle-head Turret-motor Angle Within Working Arc can control the
travel rate and discharge, the latter as an auxiliary function.
[3769] With sufficient circumferential clearance, a `cooling`
catheter connected to a cold air gun passed down the central canal
or a service channel as the source of hot or cold air does not
interfere with rotatory use of the turret-motor. The recovery
electromagnets and trap-filter are used to recover any
mispositioned miniballs. Use of the most effective temperature for
achieving the elimination of vulnerable plaque while avoiding
thrombogenesis is also important for avoiding thrombosis and
tackiness (stickiness, cling) as the muzzle-head progresses. The
advisability of using platelet blockade, lubricants that afford the
polytetrafluoroethylene-coated muzzle-head further slipperiness in
the presence of clotting and that remain effective at the
temperatures used, and medication to suppress hyperplasia is
clear.
[3770] The process is not more traumatizing than alternative means
for performing an atherectomy, to include rotating razors or
cutting balloons. The initial positioning and final withdrawal of
the barrel-assembly are performed manually. During the time that an
ablation or ablation and angioplasty-capable barrel-assembly is
used to perform an ablation or an angioplasty, either free
manipulability or machine-control over the rate of advancement or
retraction (withdrawal) may be of greater benefit. Whereas direct
manipulation of the barrel-assembly affords quick intuitive control
over transluminal positioning and the rate of movement, connection
of the barrel-assembly to an airgun mounted on or to a separate
linear stage affords precision in the transluminal translation
rate. Engagement within a linear stage prevents direct manual
control over the transluminal positioning of the barrel-assembly
within the lumen.
[3771] Freedom of movement is best afforded by direct manipulation.
However, when to minimize trauma to the lumen wall the time of
contact with the heating, chilling, or ablative muzzle-head would
best be precisely controlled, the use of the linear stage is
preferrable. When the distance between segments for treatment is
not significant, the linear stage can be used to move from one to
the next. Even when the entire procedure is automated, quick
heating and cooling with cooling service-catheters and the use of
attachments such as a cold air gun or CO.sub.2 cylinder will
require manual support through a side-socket as addressed below in
the section entitled Barrel-assembly Side-socket. Lacking an
internal transluminal mover, barrel-assemblies must be inserted
into an airgun mounted on a linear stage or a separate linear stage
for machine executed transluminal movement.
[3772] Coming after a manually controlled ablation or angioplasty,
this does not represent a loss of functionality, because:
[3773] 1. Transluminal advancement and withdrawal by minute
increments is primarily needed to achieve a uniform close
distribution pattern of miniballs containing ferrous material
during implantation discharge so as to obtain an even distribution
of the resultant stent magnetic force, and
[3774] 2. The ablation or angioplasty usually involves one or well
separated segments suited to direct manual control rather than
movement by fine incremental steps.
[3775] Reciprocally, exactitude and consistency in the rate of
passage is not important during discharge but may be of
considerable importance during tje use of ablation or a radial
projection unit shaving or brush-type tissue removing tool-inserts,
thermal tissue reduction (thermoplasty), or cryogenic angioplasty
(cryoplasty), for example.
[3776] VII2h. Ablation and Ablation and Angioplasty-Capable
Barrel-Assemblies
[3777] When slightly oversized, the muzzle-head body itself can
exert balloon-like compression on protrusive plaque, but as is true
with a balloon, this can dislodge vulnerable plaque, and the
deployment of a embolic trap-filter ahead of the muzzle-head has
itself been implicated in dislodging plaque. Angioplasty-capable
barrel-assemblies may be used independently of an airgun to
significantly reduce if not eliminate plaque prior to the insertion
of a conventional or endoluminal stent, or following use for
angioplasty independently of an airgun, can be inserted into an
airgun to initiate stenting without withdrawal from the ductus. For
both angioplasty and stenting functions, extreme limitation in
diameter and a severe requirement for steerability as a functional
combination of flexibility and stiffness represent the primary
constraints imposed upon such components as may be devised.
[3778] Enhanced versatility and freedom of movement of the
angioplasty-capable barrel-assembly as independent of the airgun
imposes greater expense. That is, an angioplasty-capable
barrel-assembly when optimized in free-standing ability requires
insertion into the airgun only for discharge. During an angioplasty
as a distinct procedure that may or may not be followed by
stenting, the need to insert the barrel-assembly into the airgun to
draw power from the power supply rather than an inmate battery or
to connect the turret-0motor to a controller-amplifier within the
cabinet of the airgun rather than to an onboard polyphase
current-generating microcircuit, involves connection that reduces
independence and freedom of movement. Except where connection must
be continuous to draw power, such connection is temporary but still
comes as an interruption.
[3779] For incorporation into an ablation or ablation and
angioplasty-capable barrel-assembly so that it can be used
independently of the airgun, miniaturized control electronics, such
as are available, for example, from Data Device Corporation,
Bohemia, N.Y., Precision MicroControl Corporation, Carlsbad,
Calif., Galil Motion Control, Rocklin, Calif., among many others
are available. Whether occlusion is associated with
atherosclerosis, fibromuscular dysplasia, stenosis attributable to
other vasculopathy, or a combination of causes, the susceptibility
of an artery to obstruction varies inversely as the cross-sectional
area of the lumen. The same may be said of many instances of
stenosis in other type ductus, some treatable with the same
apparatus, which is rarely if ever without concurrent medical
(drug) treatment.
[3780] That the principal factor predisposing to occlusion is
smallness in lumen diameter makes severe limitation in diameter the
chief design constraint upon any catheter-based device. Any
effective mechanical device for intervening in this occlusive
process must be able to reach such sites. Because plaque tends to
accumulate at points in the vasculature that are intrinsically
subject to turbulent flow--at angular turns at the entries or ostia
of branches, bifurcations, at convolutions and over tortuous
stretches, in the extremities where increased distance from the
heart results in the reduction of propulsive force and an increase
in the effects of gravity--the protrusion of plaque into the lumen
only makes flow past such points even more turbulent, hence,
thrombogenic.
[3781] The propensity to favor twists and turns adds steerability
to restriction in diameter as a basic requirement for
barrel-assemblies; essentially, the more difficult it is to reach a
certain point, the more probable is it that that will be a point
that has to be reached. For post-acute event patients resistant to
medical treatment, thrombectomy will usually be essential, and for
any patient predisposed to an acute event by advanced occlusive
disease, an atherectomy may be recommended. However, severe
limitation in diameter precludes incorporating two different
rotating tools, one for thrombectomy and the other for atherectomy,
in the same barrel-assembly. Unlike power burrs, which are suited
to removing hard plaque but not soft material, a laser can remove
both thrombi and all but exceptionally calcified plaque.
[3782] This leaves only the occasional need to cut through very
hard plaque as necessitating the antecedent use of a separate
conventional rotational atherectomy or other mechanical rotational
ablation, or rotablation, device. Simple balloons can compress
softer plaque and place an expandable stent, but not in a single
operation as would allow entry and withdrawal only once.
Furthermore, the need for more than one stent is common, and to
place these with a balloon necessitates reentry to place each
stent. Using existing means for clearing the lumen and stenting,
entry and withdrawal is required at least twice, because the lumen
must be cleared of plaque before stenting can commence. A device
that having been introduced transluminally but a single time can
remove and not just crush plaque up against the lumen wall and can
proceed to effect stenting at multiple locations along the same
vessel clearly reduces operating time and the risk of
complications.
[3783] Whereas balloon angioplasty is often performed to expand the
vessel following thrombectomy, here the muzzle-head, while not
forcibly inflated to risk dissections, still imparts some
straightening and expansion likely to suffice in less refractory
cases. When the balloon cannot pass the lesion without the need for
rotablation, the residual plaque may still be too hard to safely
mash against the lumen wall. The balloon may necessitate the
preliminary opening of a channel large enough for the balloon to be
entered, but then does not provide means for the intermediate
removal of hard plaque following rotablation and preceding
angioplasty. Here, in addition to initiating stenting, the
barrel-assembly can provide ancillary means for expanding a
post-rotablated lumen with less risk of producing dissections in
the form of radial projection unit tool-inserts and a laser, and
here too, the muzzle-head, while not inflated, in and of itself
still imparts some straightening and expansion.
[3784] A stated object here is to minimize operating time and
therewith the time of interrupted oxygenation. While extraluminal
stenting necessitates separate access through an incision to place
the stent-jacket, this is often possible under a regional if not
local anesthetic at a later date. Over and above the desirability
of reducing entries and withdrawals, when anesthesia is general,
reducing procedure time is conducive to a more favorable outcome.
Thus, currently no device combines an atherectomy or atherotomy and
an angioplasty capability with the ability to initiate stenting in
a single device as does a barrel-assembly with radial projection
units as described below. Radial projection units are suited to
assist a primary mechanism, whether a burr or laser, for the
removal of occlusive matter.
[3785] Instances inevitably arising whereby to scrape all the
peripheral plaque as may remain would simply take too much time,
such use is always discretionary on the part of the operator. In
integrating a means for the ablation of lesions atheromatous or
otherwise into the muzzle-head, the cardinal desiderata remain safe
trackability and minimized operative duration. While combining
atherectomizing and the intraductal component of extraluminal
stenting means in the same transluminal device can significantly
reduce if not eliminate the need for withdrawal and reentry and
thus reduce the duration of the procedure and the risk of entry
wound complications, to accomplish this at the expense of increased
risk of ischemia because the barrel-assembly has been increased in
diameter is counterproductive.
[3786] The most widely accepted means for opening occluded vessels
are the rotational atherectomy burr, such as made by Boston
Scientific and the laser catheter, such as made by Spectranetics.
Neither device can eliminate plaque up to the lumen wall, because
to do so risks injury that can result in abrupt closure or
perforation; the prior art makes it clear that the incorporation
into the barrel-assembly of a laser is limited for practical
reasons to the longitudinal or central axis of the barrel-assembly.
This is no less true when either of these devices are incorporated
into the barrel-assembly. However, the incorporation of radial
projection units into the muzzle-head provides a followup mechanism
for removing residual plaque once the burr or laser has passed.
[3787] Broadly, to afford clearance for the passage of the blood
demands minimizing the diameter of the barrel-assembly, which in
turn demands reduction in the number and/or diameter of barrels,
hence, of the diameter of the miniballs that may be used. The need
to use miniballs of smaller diameter in the wall of a vessel must
always be compensated for with a higher density distribution in
order to more uniformly distribute the magnetic traction and thus
reduce the risk of an eventual vessel wall perforation by an
isolated miniball of a tissue insinuative diameter under excessive
magnetic traction. Essentially adapted from the high-speed drills
used by dentists, rotational and directional atherectomy devices
use a cutter rotated by an air turbine. Other examples of combined
function devices are powered cutting balloons that atherectomize
and passive rotational cutting balloons that atherotomize.
[3788] Powered rotational burrs, passive cryogenic, thermal,
ultrasonic, and laser devices are single-function atherectomy
devices that remove hard prominences, reducing the risk of
dissections and restenosis as would otherwise be more likely to
result from the angioplasty performed next (see Safian, R. D.,
Freed, M., Reddy, V., Kuntz, R. E., Baim, D. S., Grines, C. L., and
O'Neill, W. W. 1996. "Do Excimer Laser Angioplasty and Rotational
Atherectomy Facilitate Balloon Angioplasty? Implications for
Lesion-specific Coronary Intervention," Journal of the American
College of Cardiology 27(3):552-559). When the muzzle-head is of
the type having the gas-return path rather than a laser catheter at
the center, one to four separate laser catheters depending upon the
unbranched diameter at the distal working tip pass through the
barrel-catheter and midway between the barrel-channels to the nose.
Short of terminating at the working end, the fibers of the separate
cables can merge to form a unitary tip or divide and merge to form
a unitary tip of larger diameter.
[3789] VII2h(1). Distinction in Ablation or Ablation and
Angioplasty-Capable Barrel-Assemblies as Unitary or Bipartite
[3790] Minimally ablation or ablation and angioplasty-capable
barrel-assemblies are addressed in the preceding section. Averting
the added cost for capabilites that are often unnecessary,
minimally ablation or ablation and angioplasty-capable
barrel-assemblies are primarily means for ballistic implantation
that include a thermal ablation or angioplasty capability as an
immediately available precaution for destroying potentially
embolizing debris that contact with the muzzle-head could release
and are not configured to function independently of an airgun to
perform an intricate or extensive ablation or angioplasty. The
bipartite (duplex, joint) barrel-assembly is paired and
divisible.
[3791] Except when reentry and withdrawal through the entry wound
is objectionable, the ability to use multiple differently equipped
sheaths with the same barrel-assembly during a procedure removes
any limitation on the number and type of radial projection unit
tool-inserts that can be brought to bear on a lumen of given
caliber. Such exchange uses the intracorporeal barrel-assembly as
in effect a guide wire. Another application for ensheathment within
a combination-form radial projection catheter of matching diameter
is to allow a more fully capable ablation or angioplasty-capable
barrel-assembly to more easily track a narrow lumen. Once
endoluminal (intravascular), the barrel-assembly is supplemented by
sliding the radial projection catheter over it to the treatment
site.
[3792] A duplex barrel-assembly is diagrammatically represented in
FIG. 71, wherein the barrel-assembly proper comprises power and
control housing 163, barrel-catheter 44, and muzzle-head 73, with
the angioplasty control panel 164 mounted to the matching
ensheathing radial projection catheter. As indicated, a
barrel-assembly proper may have any number of matching radial
projection catheters where the barrel-assembly proper and its
projection catheters comprise a set. Division into an axial or
inner primary barrel-assembly or barrel-assembly proper and an
ensheathing or secondary projection catheter allows reducing the
primary or barrel-assembly proper, which is usually moved to the
treatment site first, to the minimum number of inmate electrical
components needed to perform a preemptive thermoplasty and to the
minimum diameter, hence, optimal trackability.
[3793] First introducing the primary alone for expedited tracking,
multiple combination-form radial projection catheters can then be
used interchangably by sliding off and thus withdrawing the one and
then sliding another on the primary. Within the limitations imposed
by the diameter of the lumen, the kinds, potential number, and
combinations of tool-inserts (qv.) to which this allows access
exceeds any needed for a practical procedure. The access to
additional tool-inserts this provides increases the kinds and
extent of mechanical action and the application of medication and
adjuvant or other therapeutic substances that can be delivered to
the treatment site.
[3794] Thus, once endoluminal (intravascular), the primary can be
supplemented with an unlimited number of electrically and/or
fluid-controlled side-looking injection, ejection, heating,
chilling, abrading, ablating, irrigating and aspirating, or
debriding, and other tool-inserts within the diameter of the lumen
treated. The two components in such a duplex barrel-assembly can be
used independently or together to combine the capabilities
respective of each. Used separately, the combination-form radial
projection catheter can accept not only a barrel-assembly but
cabled devices, such as an angioscope, laser, or a rotary
atherectomy or thrombectomy cutting tool, for example. Whether the
normal anatomy, distended due to disease, or dilated with
medication, an initially larger lumen that gradually narrows can be
treated by sliding an outer combination-form radial projection
catheter over an inner one.
[3795] An embolic filter can be incorporated in nose 64 of distal
muzzle-head 73; however, the more so as the lumen narrows, the use
thereof is usually not feasible, unnecessary, and as addressed
below in the section entitled Embolic Trap Filter in Radial
Discharge Muzzle-heads for Use in the Vascular Tree, may prove
counterproductive. Simple pipe type barrel-assemblies may be
duplex, but used only manually, do not incorporate a forward drive
and sag leveling and stabilizing device. Thus, minimally capable
barrel-assemblies angioplasty only as adjunctive to stenting
implantation while remaining inserted in the airgun rather than as
a distinct preliminary procedure during which the barrel-assembly
is used prior to insetion in the airgun.
[3796] That is, thermoplasty capability is included only to the
extent necessary to prevent or mitigate the consequences of any
midprocedural ruptures of plaques, electrically operated radial
projection units included in the muzzle-head to allow the use of
spring-released syringe ejectors that emit a lubricant to aid in
tracking or to inject the lumen wall with a therapeutic fluid such
as a tumefacient and/or an antibiotic in preparation for
implantation, for example. A nose heat-window that makes the
additional inclusion of an embolic filter, which would require an
increase in diameter and add to the cost at slight if any residual
benefit, is provided.
[3797] Still minimally capable barrel-assemblies for vessels with a
heavier burden of plaque warrant the addition of side heat-windows
and ablative capability as inmate means that respond immediately
without a power and control housing hand grip and therewith, the
range of capability and the cost of independent sufficiency;
however, such reliance pertains over a small range before the need
for a fully capable barrel-assembly is indicated. Also to allow a
smaller diameter and greater flexibility to the extent necessary,
radial projection circuits in the muzzle-head are electrical rather
than fluid. Actual barrel-assemblies transition over a wide
spectrum from minimally to fully capable and self-contained, so
that a barrel-assembly of intermediate size might well include a
fluid circuit, for example.
[3798] By contrast, ablation or ablation and angioplasty-capable
barrel-assemblies must be capable of performing an ablation or an
angioplasty as a primary function, independently of an airgun,
whether insertion in an airgun and ballistic implantation are to
follow or not. Except with respect to those of larger diameter
which incorporate as many radial projection circuits as necessary
in the muzzle-head and/or along the sides of the barrel-catheter
without the need to be ensheathed within and thus joined with a
combination-form or through-bore type radial projection catheter,
an ablation or ablation and angioplasty-capable barrel-assembly
that must achieve a small diameter to expedite introduction and
tracking once introduced is supplemented with a size-matched
matching combination-form radial projection catheter.
[3799] A minimally capable barrel-assembly can be converted to a
fully capable barrel-assembly by further adding a slidable power
and control housing. An ablation or ablation and
angioplasty-capable barrel-assembly allowed sufficient diameter
incorporates all of the tools required and is unitary, whereas one
that must pass through lumina so narrow that an embolic filter and
radial projection units other than a nose heat-window and a few
others to aid transluminal movement must be eliminated requires
that additional tools be relegated to a separate sleeve or sheath.
It is only when the diameter of the lumen becomes so narrow that
the sheath or combination-form radial projection catheter can no
longer be added that it becomes necessary to first enter with a
projection catheter which must be withdrawn so that a radial
discharge monobarrel can be introduced.
[3800] The separate sheath is a size-matched through-bore or
combination-form radial projection catheter, which in any size can
be used independently of a barrel-assembly. A combination-type
projection catheter can be used with the bore empty or occupied by
any of several different cabled devices or an embolic filter, for
example. In using a duplex barrel-assembly, trackability is
maximized by passing the muzzle-head to the most distal treatment
site at the outset while not ensheathed within the radial
projection catheter. If this action involves the use of the linear
positioning stage, then the forward drive and sag leveling and
stabilizing device is used.
[3801] Once the treatment site has been reached or at any other
time, the projection catheter is slipped over the barrel-assembly
using its barrel-catheter as a guide wire. The stiffness added by
ensheathment within the radial projection catheter eliminates the
need for a forward drive and sag leveling and stabilizing device
over any extracorporeal length of the barrel-catheter to which the
projection catheter proximally extends. Atheromatous arteries
impose stringent constraints on diameter, necessitating pressure
diversion channels, and when end-arterial or supplying an unshared
territory such as the coronaries or mostly unshared territory such
as the carotids, debris removal requires an embolic filter and/or
nose heat-window and/or aspiration tool-inserts.
[3802] Atheromatous arteries impose stringent constraints on
diameter, necessitating pressure diversion channels, and when
end-arterial or supplying an unshared territory such as the
coronaries or mostly unshared territory such as the carotids,
debris removal requires an embolic filter and/or nose heat-window
and/or aspiration tool-inserts. Using the apparatus described
herein to perform an angioplasty and/or other therapy to be
followed by ballistic stenting implantation without the need to
withdraw and reenter, only the smallest arteries with critical
fields may prohibit the use of even the narrowest monobarrel while
ensheathed and thus require a first entry with a simple radial
projection catheter for preparatory treatment followed by a second
entry with a radial discharge monobarrel to place miniballs.
[3803] Except in this circumstance, stenting preliminary or
preparatory treatment and stenting implantation are accomplished
with a single entry. However, arteries of such small size should
rarely present lesions that a radial discharge monobarrel with nose
heat-window cannot treat without the need for ensheathment. When
necessary to achieve a small enough diameter, radial projection
units incorporated into the muzzle-head are limited to a few
operated electrically used to emit a lubricant or medication while
advancing toward, and/or injecting the lumen wall upon initial
approach to, the treatment site.
[3804] Setting aside the need for a fiberoptic endoscope (see, for
example, Miskolczi, L., Flaherty, J. D., Guterman, L. R., and
Hopkins, L. N. 2001. "Case Report: Carbon Dioxide Column
Angioscopy: A New Endovascular Imaging Technique," American Journal
of Neuroradiology 22(10):1849-1853; Soper, T. D., Haynor, D. R.,
Glenny, R. W., and Seibel, E. J. 2010. "In Vivo Validation of a
Hybrid Tracking System for Navigation of an Ultrathin Bronchoscope
within Peripheral Airways,". Institute of Electrical and
Electronics Engineers Transactions on Biomedical Engineering.
57(3):736-745) or other viewing device, and in embodiments for use
to perform an angioplasty, an embolic filter, as well as the number
of electrical or fluid radial projection circuits, the basic
sequence of increasing diameters is:
[3805] 1. Simple radial projection catheter followed by radial
discharge monobarrel-assembly.
[3806] 2. Joint, such as bipartite or duplex, angioplasty-capable
barrel-assembly, the ballistic component usually introduced alone
first for easier tracking, and
[3807] 3. Unitary or integral angioplasty-capable barrel-assembly
with only electrical radial projection circuits; and Unitary
angioplasty-capable barrel-assembly with fluid radial projection
circuits.
[3808] Rather than a combination-form radial projection catheter,
the outer component in a bipartite ablation or ablation and
angioplasty-capable barrel-assembly can be an inner and/or outer
diameter adaptor and/or a heating or cooling jacket. These can
uniformly warm or chill over the entire outer surface or be
provided with heat-windows as addressed above in the section
entitled Thermal Conduction Windows (Heat-windows) and Insulation
of the Muzzle-head Body in Thermal Ablation or Thermal Angioplasty
Minimally or Fully Capable (Independently Usable)
Barrel-assemblies.
[3809] Uniformly distributed or regionalized pores in the surface
can release a fluid continuously pumped through an end or
side-socket of the kind addressed in the sections above entitled
Ablation or ablation and angioplasty-capable Barrel-assembly
End-socket and Ablation and Angioplasty-capable Barrel-assembly
Side-socket. Such a steam jacket-like sheath is not internally
differentiated or piped; topically distinct locations for fine and
targeted control over release or aspiration are accomplished by
means of radial projection units.
[3810] VII2h(2). Specific Advantages in the Elimination or
Minimization of Connection to the Airgun (Tethering)
[3811] Since an ablation or angioplasty-incapable barrel-assemby is
used only while engaged in an airgun, the elimination of tethering
pertains only to angioplasty-capable barrel-assemblies. During an
angioplasty, the barrel-assembly is powered from the on-board
lithium-polymer or silver-zinc battery pack in the hand-grip at the
proximal end, and as preferred for freedom of movement, untethered,
hence, physically independent from the airgun or any other
apparatus. Battery power is always used for the radial projection
units and use of the turret-motor and/or electomagnet windings in
their secondary nonpositional function as heat sources for thermal
angioplasty. Angioplasty-capable barrel-assemblies must be tethered
only when the source of high or low temperature is a vortex-tube
based gun that must be supplied with compressed air from a canister
(cylinder, air tank).
[3812] Such connection is not through the airgun but rather
directly to the air tank through a very pliant hose. Placing all of
the control electronics, the propulsive gas supply cartridge, and
other components within the airgun cabinet, necessitating that the
barrel-assembly be left engaged within the airgun barrel for these
components to function would economize by avoiding the need for
microminiaturization. However, the functional superiority of
barrel-assembly operability independently of the airgun cabinet or
chassis to perform an ablation or angioplasty outweighs any such
economy; an ablation or ablation and angioplasty-capable
barrel-assembly might always be used as an independent apparatus
for these processes without ever being inserted into an airgun as
its barrel for effecting implant discharge.
[3813] Thus, were an angioplasty-capable barrel-assembly to be
dependent upon the airgun chassis as lacking inmate (on-board,
self-contrained, internal) control electronics and an end-plug for
connecting a nitrous or oxide or carbon dioxide cartridge,
connection to the positional and temperature control components
through the airgun during an angioplasty would be necessary
frequently for:
[3814] 1. Temporarily connecting the turret-motor to the controller
and drive through the airgun to:
[3815] a. Rotate the muzzle-head in order to:
[3816] (1) Redirect a thermal window, especially when heating is
eccentric through the use of a single electromagnet or motor
winding.
[3817] (2) Redirect the radial projection units, so that a
different type brush type tool-insert, for example, can be applied,
such as rotating from one with microshavers to one with
microbristles.
[3818] b. Oscillate the muzzle-head either by detuning the
turret-motor drive velocity loop for random response, or as
mentioned above in the section entitled Concept of the Extraluminal
Stent and the Means for Its Placement, programming the
servocontroller for controlled oscillation in order to:
[3819] (1) Free the muzzle-head if stuck, the use of a lubricant,
if necessary, achieved by injection through a service-channel
catheter.
[3820] (2) Assist in passing a a tortuous course of the ductus if
and only if the risk of serious injury is judged not to be present.
The intrinsic lubricity of the muzzle-head and the ability to
lubricate and oscillate the muzzle-head if necessary make the need
for surgical removal hardly possible.
[3821] (3) Apply a radial projection unit tool-insert, such as a
side-sweeper, in a vibratory manner.
[3822] However,
[3823] a. Connection (coupling) of a laser, rotational, or other
mechanical-type atherectomy cutting head cable in a
combination-form or barrel-assembly that incorporates such
(addressed below) is not through the airgun but rather to the
respective control console.
[3824] b. Connection of a cooling catheter (addressed below), which
if not permanently installed in the central canal of an
edge-discharge barrel-assembly with nose-window is usually
prepositioned within the barrel-assembly for immediate use, or
connection without a cooling catheter directly to the central canal
or a spare barrel-tube (addressed below) is directly to the vortex
tube, which in turn is connected by a hose to a tank of compressed
air or a nitrous oxide or carbon dioxide cartridge attached to the
back (proximal) end of the barrel-assembly.
[3825] When a vortex tube (addressed below) is used for thermal or
cryogenic ablation or angioplasty, it is mounted to the outside of
the interventional airgun cabinet (enclosure). The air tank or
canister containing the filtered compressed air for the cold (or
hot) air gun is mounted to the airgun cabinet supporting stand.
Exceptionally, the use of a vortex tube does not allow an ablation
or ablation and angioplasty-capable barrel-assembly to be
completely disconnected; however, connection by a pliant hose to
the air tank need not impede freedom of movement. Thus, except in
this circumstance, the proximal end of the barrel-assembly is
unconnected and freely movable.
[3826] In an angioplasty-capable barrel-assembly with a 3-phase
motor drive servocontrol microchip incorporated into the hand-grip
shaped battery pack, the muzzle-head can be oscillated or rotated
without the need to insert and thus electrically connect it through
the airgun. Of these three functions that necessitate the
predischarge insertion of the barrel-assembly into the airgun or
connection of the barrel-assembly to a cable, the first, to draw
control current for rotating the turret-motor, can be eliminated by
incorporating a nonvariable speed microcircuit controller and drive
that draw power from the inmate battery into the hand-grip.
[3827] Companies that produce or are able to produce micromotors
and microcircuit controllers include Maxon Miniature Motors,
Burlingame, Calif.; Solitron Devices, West Palm Beach, Fla.; Contec
Microelectronics, Osaka, Japan (San Jose, Calif.); Micromot
Controls, Maharashtra, India; Precision MicroContol Corporation,
Carlsbad, Calif.; Precision MicroDynamics Incorporated, Victoria,
British Columbia; ProDex Incorporated, Santa Ana, Calif.; and the
Xajong company, Taichung, Taiwan. Considering each in turn:
[3828] 1. When for simplicity and economy, the incorporation into
the hand-grip of an auxiliary controller and drive consisting of a
highly miniaturized version of the Data Device Corporation
PWR-82332 or SatCon 8314C type, for example, for delivering
polyphase current to the turret-motor windings to rotate the
turret-motor is not contemplated, and the muzzle-head cannot be
manually rotated with the necessary or without risk of stretching
injury or dissections, then rotating the muzzle-head requires
temporary connection of the turret-motor to the controller and
drive housed within the cabinet of the interventional airgun.
Temporary connection of the turret-motor to the airgun power supply
is through contacts located at the proximal end of the
barrel-catheter as shown in FIG. 72 when the barrel-assembly is
engaged in the airgun chamber as shown in FIG. 74. When connection
is through a cable located at the front of the airgun muzzle as
shown in FIG. 75, connection need not be broken by removal of the
barrel-assembly. Such an angioplasty-capable barrel-assembly is
suitable for procedures not likely to require rotation of the
muzzle-head.
[3829] 2. A combination-form angioplasty-capable barrel-assembly
that incorporates a rotary burr or excimer laser requires a power
cable that terminates proximally at the bottom of the
barrel-assembly or in a socket at the rear (proxmal) end of the
central canal for temporary connection to the control console.
Albeit inconsequentially, during intervals when the atherectomy
component is connected, complete freedom of movement is
curtailed.
[3830] 3. If the turret-motor and/or tractive electromagnet
windings had just been used for thermal angioplasty, the
counter-thrombogenic requirement to immediately cool the
muzzle-head down to body temperature following thermal use applies
no less in this situation.
[3831] VII2h(3). The Radial Discharge Barrel-Assembly as a Separate
and Independent Angioplasty Device
[3832] An object of the invention is to provide a single means for
angioplasty and stenting such that the barrel-assembly having been
introduced for angioplasty even when stenting had not been planned,
stenting can nevertheless proceed without the need for withdrawal
and reentry. To proceed with stenting must require no more than to
insert the free (extracorporeal, proximal) end of the
barrel-assembly into the airgun. Accordingly, to the extent that
such compatibility allows, the radial discharge barrel-assembly is
devised to be usable as a separate device for angioplasty without
the need to reconfigure it in order to allow its use with an airgun
to initiate stenting.
[3833] Angioplasty-capable barrel-assemblies, to include those
incorporating radial projection unit side-shaving or abrading-brush
type tool-inserts, means for thermal angioplasty, and
combination-forms that incorporate a rotary burr or excimer laser
are described below under the section entitled Types of Combination
form Barrel-assemblies. Rather than inefficiently and awkwardly
tethered by gas and electrical lines, the ablation or ablation and
angioplasty-capable barrel-assembly has directly attached to it a
small gas cylinder connected through the end or side-socket, as
addressed in the section above entitled Engagement of the
Barrel-assembly in the Airgun and the section below entitled
Barrel-assembly Side-socket.
[3834] If piped, the chilled gas is delivered directly to the
radial projection unit from the preconnected cylinder through the
pipe. In that case, substances previously delivered through the
pipe may necessitate the delivery through a service-catheter passed
down the pipe. Nonpiped radial projection units must be chilled by
a preconnected cylinder and cooling catheter. The direct exposure
to the chilling gas makes piped units retract more quickly. For
example, the body of the muzzle-head distal to the turret-motor is
not made inflateable, various balloons having finger or
bristle-like protrusions having long been available.
[3835] In use for angioplasty, the barrel-tubes serve with the
blood-tunnels, centering devices, and the free insertion or removal
down unused barrel-tubes or the central canal of the
barrel-assembly of separate tubing of any pliancy, and such use of
a cooling catheter as described above in the section entitled
Cooling Catheters (Temperature-changing Catheters) as passive
stiffeners, the number, material, wall thickness, and diameters of
barrel-tubes and absent number, the same variables as pertain to
the barrel-catheter representing various variables that contribute
to barrel-catheter stiffness, which accordingly covers a wide
spectrum. Use independently of the airgun for ablation,
angioplasty, or to actuate radial projection unit injection or
ejection tool-inserts, for example, requires that the
barrel-assembly be provided with onboard and airgun-independent
sources of electrical power and control.
[3836] As shown in FIGS. 71b and 80, a barrel-assembly for use
independently of the airgun is provided with an onboard power and
control housing with generally indicated integral control panel,
which can be slid along and off the proximal end of the
barrel-catheter. When the power and control housing is unique to a
specific barrel-assembly, the controls exactly match the
non-discharge ablation or angioplasty components to be controlled
in that barrel-assembly. A universal power and control housing
includes controls for use with any barrel-assembly all of which
would actually be needed only with a fully ablation and
angioplasty-capable barrel-assembly.
[3837] FIG. 79 shows a dedicated control panel on the power and
control housing specific to an ablation or angioplasty
barrel-assembly having two shaver or abrading brush-type
tool-inserts, recovery electromagnet and turret-motor windings that
can also be used as heating elements, but not fluid radial
projection units, an embolic filter, inmate laser, or rotational
atherectomy cutting tool, for example. Except when it is desired to
do some `touching-up` after having initiated discharge, an ablation
or ablation and angioplasty-capable barrel-assembly is used to
perform an angioplasty manually, with the barrel-assembly
independent of an airgun. Rotation and transluminal reciprocation
of the radial projection units is normally manual.
[3838] The conformation and bristle or individual projection tip
type as shown in FIG. 51B determine the kind of action that should
be applied. The oscillatory mode of the turret-motor addressed
above in the section entitled Turret-motor Operational Modes can be
used to increase the vigor or brushing. For the ablation or
angioplasty, power to the turret-motor might be needed to heat the
windings for thermal angioplasty or to drive the motor in one or
more of its oscillatory or vibratory modes in order to increase the
vigor of abrasion. Combining or overlapping these different
responses so that the motor can be used both to heat and rotate the
muzzle-head simultaneously is precluded by the mutually exclusive
controls for each function.
[3839] The turret-motor is incapable of significant abrasive action
in its rotatory mode, so that in situations where the
barrel-assembly is readily rotated by hand, this mode is not needed
in the barrel-assembly as independent from the airgun. Since
reciprocal transluminal action is manual as well, no joystick
control as shown in FIG. 83 and functionally depicted in FIG. 84 is
needed. Instead, as shown in FIG. 79, the angioplasty control panel
motor control rocker switch marked `T-motor` in the upper left-hand
corner switches between the heating and oscillatory modes. Any
different oscillatory modes programmed are cycled through by
re-depressing the right-hand side of the rocker switch and thus not
seen in the control panel shown in FIG. 79.
[3840] To minimize extracorporeal extension, the barrel-assembly is
selected according to the actual intracorporeal length required,
the forward drive and sag leveling and stabilizing device described
below assisting to avert extracorporeal bends or kinks as would
result from the mass posed by the electrical connections or a
battery pack and onboard angioplasty control panel toward the free
end. Whether connected to an external source of power by a power
cord or incorporating an inmate battery pack, ordinarily
lithium-polymer with current battery technology, the
barrel-catheter can continue as independently powered even when
inserted into an airgun.
[3841] VII2h(4). Componentry Required for Airgun-Independent
Use
[3842] An ablation or ablation and angioplasty-capable
barrel-assembly is self-contained and capable of performing an
ablation or angioplasty as separate and independent of an airgun.
An angioplasty-capable barrel-assembly encompasses the capability
of an ablation-capable embodiment, but additionly includes gas
return channels to prevent gas from entering the bloodstream. This
factor of internal structure is not reflected in the controls seen
on the onboard control panel, which are the same for both types;
however, barrel-assemblies for use in the bloodstream are equipped
with a run-ahead trap-filter, as addressed above in the section
entitled Embolic Trap Filter in Radial Discharge Muzzle-heads for
Use in the Vascular Tree, with the trap-filter control on the
panel.
[3843] As usually do minimally ablation and angioplasty-capable
barrel-assemblies, barrel-assemblies independently capable
incorporate radial projection units, addressed below in the section
entitled Muzzle-head Radial Projection Units heat-windows, below
under Thermal Conduction Windows (Heat-windows) and Insulation of
the Muzzle-head Body in Thermal Ablation or Thermal
Angioplasty-capable Barrel-assemblies, a trap-filter, and has
connectors for fluid lines. In independent use, rotation and
transluminal movement with an ablation or ablation and
angioplasty-capable barrel-assembly is manual. Fine directional
control can be of assistance in controlling slot-configured or
directional heat-windows, and oscillatory control for use use with
radial projection units.
[3844] A turret-motor always contained in the muzzle-head, the
onboard controls can include the different turret-motor operational
modes independently of the motor control electronics in the airgun
enclosure. Turret-motor operational modes include rotation,
oscillation, and use of the turret-motor field rotating winding to
supply heat, as described above in the section entitled
Turret-motor Operational Modes. For procedures where speed is of
the essence, the additional expense for adding these controls is
justified. However, not contained within the barrel-assembly, the
use of a linear stage for fine control over transluminal movement
will still require insertion into an airgun mounted on a linear
stage or into a separate linear stage as addressed below in the
section entitled Ablation or ablation and angioplasty-capable
Barrel-assembly Control and Onboard Control Panel.
[3845] A thermal angioplasty, or vascular thermoplasty, capable
barrel-assembly need only be adjusted in the temperature of its
heat-windows or other heating elements to allow its use for a
thermal ablation, or thermoablation, in a nonvascular ductus. A
barrel-assembly that is ablation-capable only is not designed for
and is not for use in the vascular tree. The addition of radial
projection units to a thermal angioplasty-capable barrel-assembly
extends this range of function to include cutting and abrasive
tools that can be used without heat for ablation or
angioplasty.
[3846] Except for limited purpose and minimally-capable
barrel-assemblies not provided with an internal power source, such
barrel-assemblies can be used independently of the airgun to
perform an ablation or angioplasty, and can do so regardless of
whether this procedure is followed by conventional stenting by
means of inserting the barrel-assembly in an interventional airgun
for stenting implantation. Performance of an ablation or an
angioplasty imposes no need to withdraw from and reenter through
the introducer sheath and irritation to the entry wound; without
withdrawing, the proximal end of the barrel-catheter is inserted in
the airgun.
[3847] For use independently of an airgun, the barrel-assembly must
be fully self-contained with distal embolic protective filter,
on-board power pack, and ablation-angioplasty control panel. In
addition to recovery electromagnets, which can be reoriented in
rotary angle with the turret-motor and transluminally by hand or
with a linear positioning stage, connection of a barrel-tube or the
distal end of the barrel-assembly as a whole to a vacuum
(aspiration) pump, and a trap-filter, such a barrel-assembly can
recover a miniball through use of the radial projection units to
reposition the miniball by means of a brushing action.
[3848] Such a barrel-assembly requires insertion into an
interventional airgun if and only if to be used for stenting
implantation. For thermal ablation of ductus other than vascular,
temperatures other than 90 degrees centrigrade must be provided.
Combination-form fully angioplasty-capable barrel-assemblies
additionally incorporate an atherectomy burr to cut through
calcified plaque if necessary or a laser to perform an atherectomy
in any type ductus. All fully angioplasty-capable barrel-assemblies
incorporate a distal embolic protective trap-filter in the nose
that can be remotely deployed or retracted.
[3849] VII2h(5). Thermal Ablation and Angioplasty- (Lumen Wall
Priming Searing- or Cautery-) Capable Barrel-Assemblies
[3850] Clinical findings that address the relative value in
angioplasty or atherectomy alone, the same plus stenting, or
stenting alone, inevitably introduce so many variables as to afford
little in the way of clear information. Instead, findings are
specific to particular vessels, particular devices, certain adverse
sequelae to the disregard of others, particular medical conditions
such as a previous acute cardiovascular event of a specific type,
details concerning the procedures used, and so on. Some
implications of endothelial dysfunction are addressed above in the
sections entitled Field of the Invention, Concept of the
Extraluminal Stent, Abrupt Closure with Thrombus and Vasospasm, and
Medicinal and Nedicated Miniballs and Stays, among others.
Vulnerable plaque within a delimited segment can pose an imminent
threat as demands its elimination regardless of the potential of
the limited extent of treated tissue to regain normal endothelial
function.
[3851] The concept delineated here consists of using statins to
expedite the healing of less severly inflamed and metaplastic
tissue, with plaque spot-treated to reduce the risk of an acute
event. Numerous methods available for spot-treating atheromas (see,
for example, Waller, B. F. 1989. "Crackers, Breakers, Stretchers,
Drillers, Scrapers, Shavers, Burners, Welders and Melters"--The
Future Treatment of Atherosclerotic Coronary Artery Disease? A
Clinical-morphologic Assessment," Journal of the American College
of Cardiology 13(5):969-987), a method that least detracts from
eventual healing is clearly to be preferred. A catheteric device
with a quickly and independently heated and cooled tip and side
windows affords a level of control over the ablative process as to
allow only so much exposure to the device as is necessary to
eliminate the threat tissue, thus predisposing to eventual recovery
to the extent possible.
[3852] As addressed herein, thermal angioplasty has the object of
destroying vulnerable plaque (see, for example, Virmani, R., Burke,
A. P., Farb, A., and Kolodgie, F. D. 2006. "Pathology of the
Vulnerable Plaque," Journal of the American College of Cardiology
47(8 Suppl):C13-C18; Virmani, R., Kolodgie, F. D., Burke, A. P.,
Finn, A. V., Gold, H. K., Tulenko, T. N., Wrenn, S. P., and Narula,
J. 2005. "Atherosclerotic Plaque Progression and Vulnerability to
Rupture: Angiogenesis as a Source of Intraplaque Hemorrhage,"
Arteriosclerosis, Thrombosis, and Vascular Biology 25(10):2054-2061
Kolodgie, F. D., Burke, A. P., Farb, A., Gold, H. K., Yuan, J.,
Narula, J., Finn, A. V., and Virmani, R. 2001. "The Thin-cap
Fibroatheroma: A Type of Vulnerable Plaque: The Major Precursor
Lesion to Acute Coronary Syndromes," Current Opinion in Cardiology
16(5):285-292) with heat and must be tightly controllable to
minimize injury to subjacent layers.
[3853] The endoluminal application of heat may also effect repair
of the ductus wall (see, for example, Resar, J. R., Wolff, M. E.,
Hruban, R. H., and Brinker, J. A. 1993. "Endoluminal Sealing of
Vascular Wall Disruptions with Radiofrequency-heated Balloon
Angioplasty," Catheterization and Cardiovascular Diagnosis
29(2):161-167; Kaplan, J., Barry, K. J., Connolly, R. J., Nardella,
P. C., Hayes, L. L., and 4 others 1993. "Healing after Arterial
Dilatation with Radiofrequency Thermal and Nonthermal Balloon
Angioplasty Systems," Journal of Investigative Surgery 6(1):33-52;
Barry, K. J., Kaplan, J., Connolly, R. J., Nardella, P., Lee, B.
I., Becker, G. J., Waller, B. F., and Callow, A. D. 1989. "The
Effect of Radiofrequency-generated Thermal Energy on the Mechanical
and Histologic Characteristics of the Arterial Wall in Vivo:
Implications for Radiofrequency Angioplasty," American Heart
Journal 117(2): 332-341).
[3854] When a calcified cap is present, consideration must be given
to whether the cap serves a protective function so that to
eliminate it would be counterproductive; extraluminal stenting,
especially by means of stays, which avoid the lumen entirely, makes
it possible to stent regardless of a moderate amount of more highly
calcified plaque without angioplasty or atherectomy. Calcified
plaque sufficiently prominent to restrict flow may necessitate a
preparatory ablation as by means of a rotatory ablator, which can
be built into an angioplasty-capable barrel-assembly.
[3855] The trend toward stenting without first performing an
angioplasty, usually in the carotid arteries, especially when
vulnerable plaque is present (see, for example, Barrera, J. G.,
Rojas, K. E., Balestrini, C., Espinel, C., Figueredo, A., and 3
others 2013. "Early Results after Synchronous Carotid Stent
Placement and Coronary Artery Bypass Graft in Patients with
Asymptomatic Carotid Stenosis," Journal of Vascular Surgery 57(2
Supplement):58S-63S; Garcia-Nielsen, L., Carreira, J. M.,
Rabellino, M., Baldi, S., Zander, T., and 3 others 2013.
"Hemodynamic Depression in Carotid Artery Stent without
Angioplasty," in Spanish with English abstract at Pubmed, Revista
De Neurologia [Journal of Neurology] 56(4):200-204; Baldi, S.,
Zander, T., Rabellino, M., Gonzalez, G., and Maynar, M. 2011.
"Carotid Artery Stenting without Angioplasty and Cerebral
Protection: A Single-center Experience with Up to 7 Years'
Follow-up," American Journal of Neuroradiology 32(4):759-763;
Rabellino, M., Garcia-Nielsen, L., Baldi, S., Zander, T., Casasola,
C., and 3 others 2010. "Non-protected Carotid Artery Stent without
Angioplasty in High-risk Patients with Carotid and Coronary Artery
Disease Undergoing Cardiac Surgery," Minimally Invasive Therapy and
Allied Technologies 19(3):184-188; Leonardi, M., Dall'olio, M.,
Raffi, L., Cenni, P., Simonetti, L., Marasco, R., and Giagnorio, F.
2008. "Carotid Stenting without Angioplasty and without Protection:
The Advantages of a Less Invasive Procedure," Interventional
Neuroradiology 14(2):153-163;" Pelz, D. M. and Lownie, S. P. 2008.
"Letter--Re: Primary Carotid Stenting without Angioplasty,"
Interventional Neuroradiology 14(4):473; Maynar, M., Baldi, S.,
Rostagno, R., Zander, T., Rabellino, M., Llorens, R., Alvarez, J.,
and Barajas F. 2007. "Carotid Stenting without Use of Balloon
Angioplasty and Distal Protection Devices: Preliminary Experience
in 100 Cases," American Journal of Neuroradiology 28(7):1378-1383;
Lownie, S. P., Pelz, D. M., Lee, D. H., Men, S., Gulka, I., and
Kalapos, P. 2005. "Efficacy of Treatment of Severe Carotid
Bifurcation Stenosis by Using Self-expanding Stents without
Deliberate Use of Angioplasty Balloons," American Journal of
Neuroradiology 26(5):1241-1248; Nakatani, M., Takeyama, Y.,
Shibata, M., Yorozuya, M., Suzuki, H., Koba, S., and Katagiri, T.
2003. "Mechanisms of Restenosis after Coronary Intervention:
Difference Between Plain Old Balloon Angioplasty and Stenting,"
Cardiovascular Pathology 12(1):40-48; Men, S., Lownie, S. P., and
Pelz, D. M. 2002. "Carotid Stenting Without Angioplasty," Canadian
Journal of Neurological Sciences 29(2):175-179; Harnek, J., Zoucas,
E., Stenram, U., and Cwikiel, W. 2002. "Insertion of
Self-expandable Nitinol Stents without Previous Balloon Angioplasty
Reduces Restenosis Compared with PTA Prior to Stenting,"
Cardiovascular and Interventional Radiology 25(5):430-436;) makes
taking measures to avoid disrupting vulnerable plaque using the
apparatus for stenting to be described all the more
significant.
[3856] Initial contact by a muzzle-head with the wall of an
atheromatous artery occurs both with an ablation or
angioplasty-incapable barrel-assembly and an ablation or ablation
and angioplasty-capable barrel-assembly. Barrel-assemblies are
usually selected to flush-fit the segment of the lumen to be
treated and are thus frequently in contact with the lumen wall.
Furthermore, though blood-grooves and other passages ameliorate the
problem, the muzzle-head substantially obstructs the lumen,
promoting means and techniques to hasten completion of the
procedure, such as the providing multiple barrel tubes and
automated discharge at preselectable specific intervals. In effect,
mere contact with the barrel-assembly as it passes along the lumen
wall exerts a weak or deficient angioplasty effect, in that it can
release debris, making the use of a trap-filter requisite.
[3857] The combination of contact with the lumen wall and haste
would risk the release of debris more were not an onboard
trap-filter incorporated. Accordingly, using the means described
herein to stent without a previous angioplasty is not recommended,
and using the means described herein to perform the angioplasty
assumes the use of the onboard trap-filter. These include providing
the muzzle-head with a nose-cap heat-window that is heated by
running current through the windings of both recovery
electromagnets. Since a distal embolic protective trap-filter would
also be capable of disrupting plaque, none is deployed when the
presence of vulnerable plaque is suspected if not confirmed. A
nose-cap heat-window is thus necessary in all but ablation or
angioplasty-incapable Barrel-assemblies which are used only to
stent implant where plaque is not present.
[3858] In addition to a nose heat-window, a fully
angioplasty-capable barrel-assembly usually has heat-windows that
conduct heat produced by passing current through the windings of
the turret-motor. Whereas the recovery electromagnet nose
heat-window must deliver heat round and about, those over the
turret-motor in an angioplasty-capable barrel-assembly are in the
form of circumferential or arcuate slits, slots, or rectangles that
can be directed toward eccentric plaque or other type lesions.
Because temperatures other than 90 degrees centigrade tend to be
thrombogenic, the insulation surrounding heat-windows whether
omnidirectional or directional (eccentric) must minimize the
generation of thrombogenic heat in the gradient areas bounding the
heat-windows.
[3859] Because of the severe restriction in thickness, perfect
insulation cannot be achieved; however, because the 90 degree focal
area continuously passes over the lumen wall, areas within the
cooling gradient bounding the heat-window within the segment of the
artery to be treated are instantly exposed to the target
temperature. Thus, the insulation is made as effective as possible
but not perfect. There will always be end of treatment areas where
the muzzle-head will not pass, and thromobolytic medication, which
is always to be administered in the smallest dose effective, must
be relied upon to protect against thromboembolisms. The same
applies when only one recovery electromagnet or the turret-motor
are used directionally to treat eccentric lesions in a blood
vessel.
[3860] A probability if not the confirmation of vulnerable plaque
warrants additional protection against the release of atheromatous
detritus. This is attained by incorporating a distal embolic
protective filter. Although not fully angioplasty-capable, such a
barrel-assembly can and therefore is made capable of performing a
thermal angioplasty independently of an airgun. Since it follows
the nose-cap thermal window at an interval, making the turret-motor
heatable is subsidiary in the preventing ruptures. To function as a
thermal angioplasty- (lumen wall priming searing- or cautery-)
capable barrel-assembly requires connection to either a. The power
supply using the side-socket or plug and socket arrangement shown
in FIG. 75 with a power cord of sufficient length to allow freedom
of movement, or b. That the barrel-assembly be made completely
separate and independent of an airgun with on-board power and
controls to perform a thermal angioplasty.
[3861] Both configurations allow access to a service-channel
whether the central canal or a spare barrel-tube to introduce a
catheter down to a muzzle-port in order to deliver medication or a
lubricant. Whether power is derived through connection to the
airgun power supply or from an on-board battery pack, to allow its
use while physically separated from the airgun, an ablation or
ablation and angioplasty-capable barrel-assembly is provided with
an on-board thermal angioplasty control panel, as addressed below
in the section entitled Ablation or ablation and
angioplasty-capable Barrel-assembly Onboard Control Panel.
[3862] In barrel-assemblies for use not limited to atheromatous
arteries, thermal ablative temperatures other than 90 degrees
centigrade are provided. Once completed, the proximal end of the
barrel-assembly is engaged in the airgun and implantation
initiated. The equal applicability of semi-tethered and nontethered
means for drawing power reflects the transitional status of such a
barrel-assembly as between angioplasty functionality that is
slavish or is independent, the choice in componentry depending upon
whether the barrel-assembly is to be usable independently.
[3863] VII2h(6). Ablation and Ablation and Angioplasty-Capable
Barrel-Assembly End-Sockets
[3864] An end-socket is the end-plate of a barrel-assembly, which
normally used to establish barrel-tube and electrical (but not
fluid) line connections when engaged in the airgun chamber as a
kind of compound jack or plug, is used instead to make fluid line
as well as electrical connections when removed from the airgun.
Electrical contact is made by engagement in the airgun chamber,
fluid attachment necessitating removal from the airgun. Outside the
airgun, an end-socket allows connection to components in the
muzzle-head defined in the glossary below, such as radial
projection units, heat-windows, and a trap-filter, to a source of
electrical power and/or various kinds of fluid moving devices, such
as an aspiration pump, cold air gun, or an auxiliary device placed
in the central canal or a barrel-tube. End-sockets not
automatically closed by a one-way swing-away cover also serve as
gas pressure relief outlets.
[3865] Ablation or ablation and angioplasty-capable and
combination-form barrel assemblies are generally equipped with a
side-socket to allow fluid and electrical connection to various
attachments whether the barrel-assembly is or is not inserted in
the airgun. Unlike a side-socket, connection through an end-socket
requires removing the barrel-assembly from the airgun, disabling
discharge, so that discharge and ablative functions cannot be
freely interspersed. Electrical and fluid connections to the
end-plate as a socket, or end-socket, is by means of miniature
connectors. Furthermore, not requiring a configuration that allows
connection within the airgun chamber, the side-socket is flexible
in configuration. That is, whereas connection to an end-socket
requires that the connecting cord or cable be of accommodating
conformation, in a side-socket, the socket can be adapted to
participate in connection. See also side-socket,
service-catheter.
[3866] VII2h(7). Ablation and Ablation and Angioplasty-Capable
Barrel-Assembly Side-Sockets
[3867] A side-socket is a receptacle in the side of a
barrel-assemblypower and control housing that allows connection of
components or tubes in the muzzle-head to a source of electrical
power and/or various kinds of fluid moving devices, such as an
aspiration pump or cold air gun or in a combination-form
barrel-assembly, for admitting or allowing connection to an
auxiliary device in the central canal without regard to whether the
barrel-assembly is engaged in the chamber of an airgun. Unlike an
end-socket, it does not establish connection within the airgun
chamber, and can therefore incorporate collars or size adapters,
for example, to accommodate input lines. Side-sockets not
automatically closed by a one-way swing-away cover also serve as
gas pressure relief outlets.
[3868] Depending upon the specific barrel-assembly, access can be
to the central canal, one or more barrel-tubes for use as
service-channels or service-catheters, or both. Fluid connections
may require that the end-plate at the proximal end of the
barrel-assembly be capped. Since placement thus allows use
independently and regardless of engagement in the airgun, cooling
or heating air or gas can be delivered whether the barrel-assembly
is separate from the airgun or during discharge; side entry, side
entry socket. See also end-socket, service-catheter. An ablation or
angioplasty-incapable barrel-assembly, such as a simple pipe, can
be used apart from an airgun for bulb or syringe pipetting or
connection to a vacuum pump for aspiration or to deliver
medication, but is otherwise always used while inserted in an
airgun.
[3869] Therefore, these barrel-assemblies lose little utility when
the electrical connection needed to power the recovery
electromagnet is established upon mechanical engagement of the
barrel-assembly with contacts in the end-plate as shown in FIG. 72
in an airgun chamber as shown in FIG. 74. Removal of a simple
barrel-assembly from the airgun for aspiration or fluid delivery
discontinues only its functions of miniball discharge and recovery,
which are not needed for these purposes; the delivery of liquid
medication during discharge requires a multibarrel-tube ablation or
ablation and angioplasty-capable barrel-assembly, usually by
insertion of a service-catheter. The delivery of medication with a
simple pipe is limited to the use of medication and medicated
miniballs.
[3870] Since a simple barrel-assembly need not be usable in
multiple ways apart from or while inserted into the airgun, access
to its proximal end for connection to various attachments offers no
benefit. However, an ablation or ablation and angioplasty-capable
barrel-assembly, which can be used to perform an angioplasty that
might be followed by conventional stenting so that it is never
inserted into an airgun, for example, improves in utility the more
it can be used independently of the airgun. Moreover, side
connections allow any functions connected thus to continue whether
the barrel-assembly is inserted into the airgun or not. For this
reason, in such a barrel-assembly, it is best to provide electrical
connectors or both electrical and hosing connections at the side
and distal enough as not to interfere with insertion of the
barrel-assembly into the airgun.
[3871] Because it does not obstruct the proximal end of the
barrel-assembly and thus does not interfere with insertion down the
barrel of the airgun and engagement in its chamber, a side-socket
allows auxiliary devices, such a rotary burr or laser atherectomy
cable, but primarily a line delivering cold air, to remain
connected even during discharge. The side-socket, like an end-plate
socket, must have an adjacent one-way pressure relief valve or
adjustable vent, which is usually mounted in a circular plate that
seen side-on is arcuate to fit against the side of the
barrel-assembly. A side-socket can be incorporated into any
barrel-assembly but is most useful in an edge-discharge
barrel-assembly, which can be made with built in cooling catheter
that directs cold (or hot) air against the proximal face and wall
of a nose-window.
[3872] Alternatively, an edge-discharge barrel-assembly can use
attachments, so that the socket passes an atherectomy cable or
cooling catheter that is introduced at the socket and fed or snaked
down to the front (distal) end so that differently equipped
combination form barrel-assemblies can be assembled using the same
basic or shell barrel-assembly. An end-plate that includes an
end-socket allows almost every form of use but not with continued
access to ablative or angioplasty functions when the
barrel-assembly must be inserted into the airgun to initiate
ballistic discharge, at which time any attachments at the proximal
end (rear) must be removed. Without a side-socket, the intima
cannot be chill stabilized during discharge, for example.
[3873] VII2h(8). Barrel-Assembly Power and Control Housing
[3874] Whereas a minimally ablation or ablation and
angioplasty-capable barrel-assembly is dependent upon the airgun
for power and control, an ablation or ablation and
angioplasty-capable barrel-assembly, whether a combination-form,
must be usable independently of an airgun. This necessitates a
self-contained or onboard source of power and control. In order to
allow a combination-form radial projection catheter of matching
size, to be slid over the barrel-catheter of such an independent
apparatus, the power and control housing must be disconnectable.
The power and control housing of an ablation or angioplasty-capable
barrel-assembly or radial projection catheter can be slid along
splines around the barrel or projection-catheter integral to the
tubing extrusion.
[3875] Electrical connection of the working components to the
airgun power supply and/or battery pack in the housing is
maintained by contacts lining the catheter hole in the housing that
ride along contacts glued into the valleys between the splines. In
larger barrel-assemblies for use in the gastrointestinal tract, for
example, some or all electrical connection can be internal to the
housing. Fluid connections generally enter through a side-port and
travel through the center of the barrel-catheter or radial
projection catheter tubing. The barrel-assembly is equipped with an
ambidextral hand-grip for grasping and to serve as a torquing
device or torquer. The hand-grip is coated for traction, such as
with vinyl or a nonallergenic synthetic rubber. In an ablation or
ablation and angioplasty-capable barrel-assembly, the hand-grip
contains a battery within and mounts an independent angioplasty
control panel on the outside.
[3876] The battery pack in an ablation or ablation and
angioplasty-capable barrel-assembly hand-grip is preferably of the
lithium polymer type and concentrically elongated along the
barrel-catheter for high storage capacity without being obtrusive.
Also with respect to ablation or ablation and angioplasty-capable
barrel-assemblies, a side-socket, as addressed above in the section
entitled Barrel-assembly Side-socket, is preferred to an
end-socket. Placed along the barrel-catheter or through the
hand-grip and thus beyond or distal to the airgun muzzle when the
barrel-assembly is inserted into the airgun, a side-socket allows
the cabling, piping, or wires of external apparatus used during the
ablation or angioplasty to remain connected whether the
barrel-assembly is inserted into or used separately from the
airgun. External apparatus includes gas cylinders, endoscopy
viewing screens, laser control consoles, and so on.
[3877] VII2h(8)(a). Connection of the Power and Control Housing to
the Airgun
[3878] The power and control housing includes a battery pack,
eliminating the need for connection to the airgun power supply.
Mechanical connection of the power and control housing to the
airgun in ablation or angioplasty-capable and minimally-capable
barrel-assemblies and radial projection catheters when applicable
is by means of a portion of barrel-catheter extending out the
proximal side of the housing which is equal in length to the airgun
barrel. Connection to the airgun muzzle is by means of a twist to
lock connector mounted to the front of the airgun muzzle, as
addressed above in the section entitled Twist-to-stop and Lock
Connector (Twist Lock Connector, Keyed Spring Lock Connector). An
ablation or ablation and angioplasty-capable barrel-assembly with
its housing removed (slipped off) or disconnected is equivalent to
a minimally ablation or ablation and angioplasty-capable
barrel-assembly. The power and control housing of a radial
projection catheter need never be disconnectable or slidable.
[3879] VII2h(8)(b). Slidable Ablation or Ablation and
Angioplasty-Capable Barrel-Assembly Power and Control Housing
[3880] An ablation or ablation and angioplasty-capable
barrel-assembly should be optimally navigable, usable independently
of an airgun, remain insertable in the airgun whether to resume
implantation discharge and/or to gain use of the linear positioning
stage, and allow sliding over the barrel-catheter with a
combination-form radial projection catheter at any moment. These
desiderata recommend the elimination of any component that would
lessen steerability or trackability, impede removal or insertion in
the airgun, or interfere with placing the radial projection
catheter. A practical ablation or ablation and angioplasty-capable
barrel-assembly allows both quick insertion and removal from the
airgun to the rear and quick disconnection and removal of a radial
projection catheter to the fore.
[3881] A barrel-assembly power and control housing affixed at a
distance along the barrel-catheter with a rear or proximal length
of barrel-catheter for insertion in the airgun would not move on
introduction into and withdrawal from the body and would require
disconnection from the forward or distal portion of the
barrel-catheter to allow insertion in the airgun by means of a plug
type connector that would demand placing joints in the
barrel-tubes. A housing at some point forward thereof, or distal to
the proximal or end of the barrel-catheter inserted in the airgun,
would likewise require disconnection by a plug type connector that
would demand placing joints in the barrel-tubes.
[3882] Moreover, when introduction of the barrel-assembly
commenced, a power and control housing hand-grip fixed in position
would have the extracorporeal length of the barrel-catheter to its
fore (distally) making use awkward and inviting excessive bowing or
buckling if not kinking over the intervening length.
Disconnectability of the power and control housing allows a
combination-form radial projection catheter to be advanced over the
barrel-assembly barrel-catheter midprocedurally whether before or
after entering the body. Incorporating fluid radial projection
units in narrower muzzle-heads and about narrower barrel-catheters
is discounted as demanding an increase in gauge, reducing the
flexibility of the barrel-assembly, requiring points of fluid
connection that unlike electrical connections are immobile and
obstructive, and demanding the use of plug type connection that
requires placing a joint in the barrel-tube or tubes.
[3883] An ablation or ablation and angioplasty-capable
barrel-assembly does not require onboard fluid control, because: 1.
While the barrel-assembly is not inserted in the airgun, an
external source of a gas or liquid can be fed through an end-port
in the terminal plate into a barrel-tube for emission in the lumen,
2. Whether to lubricate passage or administer medication or another
therapeutic liquid substance, the electrically operated radial
projection units in the muzzle-head can use spring discharge
syringe tool-inserts to eject the liquid substance in the lumen or
inject it into the lumen wall, and 3. A combination-form radial
projection catheter matched in gauge and length to the
barrel-assembly is not inserted in the airgun, is passable over the
previously situated barrel-catheter used as a guidewire, can thus
readily accommodate a fluid circuit or circuits with power and
controls for these within its own power and control housing, and 4.
The projection catheter can be advanced over or removed from the
barrel-catheter at any time before or after the barrel-assembly is
inserted in the airgun and the end-port is not in use.
[3884] Thus, for the radial projection units in the muzzle-head,
purely electrical operation is not just necessary but superior.
Muzzle-head units are favorably limited to electrical units, a need
for fluid units relegated to a matching radial projection catheter.
Electrically operated radial projection units about the muzzle-head
can use tool-inserts that can perform any endoluminal procedure
that does not involve the continuous delivery or removal of an
ejectant or injectant. For example, electrical/fluid system-neutral
ejection syringe tool-inserts, or spring release syringe ejectors,
can be used to release a lubricant to expedite navigation. By
pushing or pulling the barrel-catheter through it, a slidable
electrical power and control housing can be moved as the
barrel-assembly is introduced and withdrawn and thus kept at a
consistent distance from the introducer sheath.
[3885] The housing includes a levered cam detent that allows it to
be slid to and locked in any position along the barrel-catheter.
Holding the housing stationary with the detent open,the
barrel-catheter can be slid through it, while locking the housing
in position allows its use as a grip. Upon withdrawal, a power and
control housing hand-grip that is fixed in position along the
length of the barrel-catheter increases the extracorporeal length
of the barrel-catheter between the hand-grip to the introducer
sheath. The chances for kinking are increased when a
barrel-assembly having a longer barrel-catheter than necessary is
used. Kinking or creasing the barrel-tubes disallows the use of
these for further discharge, necessitating withdrawal to replace
the barrel-assembly.
[3886] More specifically, when disengaged from the airgun and the
housings stand in ganged relation with the power and control
housing of the barrel-assembly held in place, the power and control
housing of the radial projection catheter can be pushed forward
against the rear of the muzzle-head carrying the barrel-assembly
forward. Provided the barrel-assembly housing is held and its
detent in closed position, when the previously advanced radial
projection catheter is pulled back, the barrel-assembly will remain
in the forward position. Holding the radial projection catherter
housing in place while pushing the barrel-catheter through the
slidable power housing of the barrel-assembly advanced the
muzzle-head through the stationary radial projection catherter.
[3887] The housing is given an overall conformation that includes
bilaterally symmetrical finger indentations or a pistol grip for
ambidextral grasping and has the control panel for the
barrel-assembly components mounted to its upper surface. Electrical
contacts inside the housing collar clutch about the
barrel-catheter. The inward faces of these contacts slide on
separate strips of silver oriented longitudinally about the
periphery of the barrel-catheter to provide continuous electrical
contact during movement. A sliding housing is used only on
barrel-assemblies, not on radial projection catheters, and includes
only electrical, not fluidic components. Neither does it include
electrical controls for a separate housing containing a fluid pump
and reservoir. A matching combination-form radial projection
catheter complements the barrel-assembly with a stationary power
and control housing that can contain onboard fluid components.
[3888] With the barrel-assembly removed from the airgun,
lubrication, irrigation, and aspiration, for example, can be
accomplished through an end-socket connected to a barrel-tube or
tubes. When not engaged in an airgun, a barrel-assembly with an
end-socket can be connected to an external source of gas or liquid.
A radial projection catheter with a side-socket in its power and
control housing also allows connection from an external source of a
gas or liquid to one or more of its fluid tool-inserts. The use of
a power cord in lieu of a battery, whether connecting to the airgun
or to another power supply, is not preferred as hindering free
movement considerably more than does the weight and size increase
that results from including the batteries onboard.
[3889] For separate and independent function, as well as logical
and intuitive consistency to ward off human error, the airgun,
barrel-assembly, and combination-form radial projection controls
not duplicated on one of the other apparatuses are kept with the
respective apparatus. For example, the linear positioning stage
controls go to the airgun and are on the airgun. When a joystick or
cyclic-type control is used, rotation of the turret-motor is by
rotating or sidewise motion and control of the linear stage by
push-pull movement. The control panel, and contains the control
circuitry and power source, usually a thin film or lithium-polymer
battery. The controls omit those related to discharge, which go to
the airgun, and include those used for separate use of the
barrel-assembly.
[3890] Controls for radial projection units in ablation or
angioplasty minimally capable barrel-assemblies, which do not have
a power and control housing for use apart from an airgun are
included in the airgun control panel, so that use of the airgun
with a more capable barrel-assembly will result in duplicate
controls for barrel-assembly functions. For optimal flexibility and
use by an assistant, barrel-assembly controls on the airgun are not
disabled when available on the barrel-assembly. Functions involved
both in ballistic discharge and separate use of the
barrel-assembly, such as setting the rotatory angle of radial
projection units in the muzzle-head, are duplicated in the airgun
and barrel-assembly control panels. An angioplasty-capable
barrel-assembly is thus made so that the hand-grip can be slid over
any portion of the barrel-catheter likely to become extracorporeal
during any given procedure.
[3891] Since the barrel-assembly must be immediately insertable
into the airgun to commence implant discharge, the conductors
cannot, for example, exit at the end-plate and fold around to a
housing that slides over the barrel-catheter. An arrangement of
sliding contacts (electrical contact shoes, paddle shoes, brushes,
wire slide-shoes) within the housing collar, one for each
electrical connection required, are directed toward the central
axis. These contacts slide over longitudinal linear contact strips
(linear electrical contacts, hot rails, linear slip-`rings`) about
the circumference of the barrel-catheter that run along the outer
surface of the barrel-catheter at circumferential intervals one for
each electrical connection required so that components within the
barrel-assembly to function in unison share such a contact
pair.
[3892] The contact strips are made of silver or coated with sputter
deposited micrometric silver islands (Salomoni, R., Leo, P.,
Montemor, A. F., Rinaldi, B. G., and Rodrigues, M. 2017.
"Antibacterial Effect of Silver Nanoparticles in Pseudomonas
aeruginosa," Nanotechnology, Science and Applications 10:115-121;
Perez-Tanoira, R., Perez-Jorge, C., Endrino, J. L., Gomez-Barrena,
E., Horwat, D., Pierson, J. F., and Esteban, J. 2012. "Bacterial
Adhesion on Biomedical Surfaces Covered by Micrometric Silver
Islands," Journal of Biomedical Materials Research. Part A
100(6):1521-1528; Monteiro, D. R., Gorup, L. F., Takamiya, A. S.,
Ruvollo-Filho, A. C., de Camargo, E. R., and Barbosa, D. B. 2009.
"The Growing Importance of Materials that Prevent Microbial
Adhesion: Antimicrobial Effect of Medical Devices Containing
Silver," International Journal of Antimicrobial Agents
34(2):103-110; Boswald, M., Mende, K., Bernschneider, W., Bonakdar,
S., Ruder, H., Kissler, H., Sieber, E., and Guggenbichler, J. P.
1999. "Biocompatibility Testing of a New Silver-impregnated
Catheter In Vivo," Infection 27 Supplement 1:S38-S42;
Guggenbichler, J. P., Boswald, M., Lugauer, S., and Krall, T. 1999.
"A New Technology of Microdispersed Silver in Polyurethane Induces
Antimicrobial Activity in Central Venous Catheters," Infection 27
Supplement 1:S16-S23; Oloffs, A., Grosse-Siestrup, C., Bisson, S.,
Rinck, M., Rudolph, R., and Gross, U. 1994. "Biocompatibility of
Silver-coated Polyurethane Catheters and Silver-coated Dacron
Material," Biomaterials 15(10):753-758).
[3893] Copper contact strips are not used (Mandinov, L., Mandinova,
A., Kyurkchiev, S., Kyurkchiev, and 11 others 2003. "Copper
Chelation Represses the Vascular Response to Injury" Proceedings of
the National Academy of Sciences of the United States of America
100(11):6700-6705). The contact strips must remain flush to the
outer surface of the barrel-catheter and not separate when the the
barrel-catheter is flexed. Bonding the strips to the
barrel-catheter, which will be made of or have an outer coextruded
surface of a fluoropolymer or polyamide, requiring surface
preparation to be bonded is by etching. (see also Brewis, D. M. and
Dahm, R. H. 2006. Adhesion to Fluoropolymers, Report 183, 16:3;
Shropshire, England: Smithers Rapra Publishing; Maynard W. C. 1996.
"Process for Bonding a Fluoropolymer to a Metal," Metal Finishing
94(6):161). Following surface preparation by Acton Technologies,
Inc. FluoroEtch.RTM. or W.L. Gore.RTM. and Associates, Inc.
TetraEtch.RTM. or blown-ion air plasma type corona, or flame
surface treated, the applicable bonding agents include NuSil
Technologies MED-1037 or MED3-4013.
[3894] A sliding hand-grip is provided by bringing the conductors
within the barrel-assembly to end-plate terminals that match the
terminals on the inside of a transparent friction fitting removable
cap keyed to align the electrical terminals. The separately
insulated bundled conductors leading from these terminals continue
through the top of the cap in a coiled extension or power cord that
leads to the hand-grip in slidable encircling relation to the
barrel-catheter. The cap contains holes to allow access through a
spare barrel-tube or the central canal as a service-channel Thus,
for example, when access through the central canal to the
muzzle-head is desired, the power cord emerges out of the top of
the cap off-center. The cylindrical passageway through the center
of the hand-grip is frictionally fitted for positionally stable
sliding movement along the barrel-catheter.
[3895] VII2h(8)(c). Universal Barrel-Assembly Power and Control
Housing
[3896] Airgun-independent incapable arrel-assemblies such as simple
pipes and ablation and angioplasty-incapable radial discharge
barrel-assemblies have no electrical components beyond a
turret-motor and recovery electromagnets, which remain in use
during discharge when the barrel-assembly is engaged in the airgun.
Minimally-capable barrel-assemblies generally include heat-windows
and radial projection units. To power the turret-motor and recovery
electromagnets, all barrel-assemblies must draw power during
discharge. For reasons of economy, airgun-independent incapable
barrel-assemblies are made to draw power continuously through
connection to the airgun power supply. Airgun-independent incapable
and capable barrel-assemblies of like diameter can use the same
removable slidable power and control housing, and insert adapters
allow the same power and control housing to be shared among
barrel-assemblies of different diameter.
[3897] Thus, considerable economy can still be attained through the
use of a shared power and control housing, especially when provided
with diameter adapters. However, because it must include the
controls for the numerous different components incorporated into
different barrel-assemblies, a universal power and control housing,
addressed below in the section entitled Universal Barrel-assembly
Power and Control Housing, tends to reduce any economic advantage,
the more so because unlike a plurality of simpler housings, it can
be used with only one barrel-assembly at a time. During discharge,
the turret-motor and recovery electromagnets serve discharge and
are therefore controlled from the discharge control panel mounted
to the airgun, connection to the airgun power supply as depicted in
FIGS. 72 and 74 or FIG. 75.
[3898] When connection to the airgun power supply is by contact
within the airgun chamber when the barrel-assembly is engaged as
depicted in FIGS. 72 and 74, disconnection upon withdrawing the
barrel-assembly to slide on the power and control housing causes a
temporary loss of power, whereas when connection is through a cable
as shown in FIG. 75, the housing can be slid on making connection
while the barrel-assembly continues to draw power from the power
supply. In airgun-independent capable embodiments, the cost for
additional onboard control electronics makes the cost for a
dedicated power source proportionally negligible. Depending upon
the application, the miniature embolic filter (filter-trap,
trap-filter) shown in FIG. 50 as parachute or umbrella-shaped might
just as easily be windsock, drag, or trawler type fishing
net-shaped.
[3899] VII2h(8)(d). Rechargeable Battery Pack Local to the
Electrical Terminals
[3900] An ablation or ablation and angioplasty-capable
barrel-assembly must be usable independently of the power supply in
the airgun. To provide the longest life with the least weight, the
battery pack onboard the barrel-assembly is of the rechargeable
thin-film, silver-zinc, lithium-ion, or lithium-ion polymer type
(see, for example, Son, I. H., Park, J. H. 3, Park, S., Park, K.,
Han, S., and 5 others 2017. "Graphene Balls for Lithium
Rechargeable Batteries with Fast Charging and High Volumetric
Energy Densities," Nature Communications 8(1):1561; Cheng, Q.,
Okamoto, Y., Tamura, N., Tsuji, M., Maruyama, S., and Matsuo, Y.
2017. "Graphene-like graphite as Fast-chargeable and High-capacity
Anode Materials for Lithium Ion Batteries," Scientific Reports
7(1):14782; Hu, P., Wang, H., Yang, Y., Yang, J., Lin, J., and Guo,
L. 2016. "Renewable Biomolecule-based Full Lithium-Ion Batteries,"
Advanced Materials (Deerfield Beach, Fla.) 28(18):3486-3492;
Zhang,R., Chen, Y., and Montazami1, R. 2015. "Ionic Liquid-doped
Gel Polymer Electrolyte for Flexible Lithium-Ion Polymer
Batteries," Materials (Basel, Switzerland) 8(5):2735-2748; Ben
Amar, A., Kouki, A. B., and Cao, H. 2015. "Power Approaches for
Implantable Medical Devices," Sensors (Basel, Switzerland)
15(11):28889-28914; Mond, H. G. and Freitag, G. 2014. "The Cardiac
Implantable Electronic Device Power Source: Evolution and
Revolution," Pacing and Clinical Electrophysiology
37(12):1728-1745; Hassoun, J., Bonaccorso, F., Agostini, M.,
Angelucci, M., Betti, M. G., and 6 others 2014. "An Advanced
Lithium-ion Battery Based on a Graphene Anode and a Lithium Iron
Phosphate Cathode," Nano Letters 14(8):4901-4906; Bock, D. C.,
Marschilok, A. C., Takeuchi, K. J., and Takeuchi, E. S. 2012.
"Batteries Used to Power Implantable Biomedical Devices,"
Electrochimica Acta 84).
[3901] VII2h(9)(e). Ablation and Ablation and Angioplasty-Capable
Onboard Barrel-Assembly Control
[3902] As addressed in the section above entitled Minimally
Ablation or Ablation and Angioplasty-capable Barrel-assembly
Control Panel, insertion in an airgun mounted on a motional control
platform allows the rate of transluminal exposure to ablative
action to be closely controlled, but interferes with free
manipulability, which requires removing the barrel-assembly from
the airgun or use of an air pistol. When, as during an ablative
process, the rate of transluminal movement is significant, a
minimally ablation or ablation and angioplasty-capable
barrel-assembly connected to a pistol affords free but not tightly
controlled movement. Situations that demand both close control over
discharge and the rate of transluminal movement require the
combination of a barrel-assembly that can be freely manipulated and
engaged in a positional control stage-mounted interventional airgun
as necessary.
[3903] For this reason, the barrel-assembly is made to be usable
independently of an airgun but insertable into an airgun for
machine controlled transluminal movement at any time. The need for
precise transluminal motion exceptional, the transluminal axis of
the joystick control, as addressed in the section that follows, is
made operational only when the barrel-assembly is engaged in an
airgun. Any tethering during an ablation or angioplasty consists of
a laser or rotational atherectomy burr cable in a combination-form
barrel-assembly. Electrically operated components other than a
linear stage are wholly contained on-board the barrel-assembly, and
means for chilling the barrel-assembly itself with or without a
cool air catheter or for performing a cryoablation (cold air gun,
CO.sub.2 cartridge) are with most embodiments connected through a
side-socket and attached to the proximal end-plate.
[3904] Transluminal positioning of the muzzle-head for discharge
that is not demanding of precision, as in moving to or between more
widely separated starting positions, can be controlled by hand;
whenever use of the linear stage for achieving millimetrically
uniform incremental positioning is not necessary, the
barrel-assembly can be removed from the airgun for free
manipulation. Whether the barrel-assembly is controlled by hand or
the linear stage, the forward drive and sag leveling and
stabilizing device is used to prevent deflection of the
extracorporeal barrel-assembly. When numerous starting positions
for finer positioning are relatively distant, it is quicker to push
or pull the airgun with the barrel-assembly inserted than to
intermittently remove the barrel-assembly for direct manual control
and reposition the airgun for insertion of the barrel-assembly.
[3905] A linear stage having an overall travel sufficient to allow
transluminal movement over a greater distance allows coarse
(approximate, rough) positioning up to one or more more widely
separated starting positions without the need for handling the
barrel-assembly. The joystick is used for continuous forward
(distad, advancing) or backward (proximad, withdrawing, retracting)
moving to the starting point. If the stage travel is too short for
continuous operation thus, then the starting position is advanced
to by manually moving the barrel-assembly, usually while removed
from engagement with the linear stage or airgun mounted
thereon.
[3906] If reaching a satisfactory starting point by hand is likely
to result in over and undershots, then once the approximate
starting point is reached by hand, exactitude in transluminal
positioning to reach the starting point is accomplished with the
the step-number and step size (distance, interval, increment)
control knobs on the angioplasty control panel, the joystick used
to indicate whether the movement is forward or backward. These same
controls are used for individual successive discharges across the
segment to be treated, each transluminal repositioning being
followed by a discharge.
[3907] A uniform close formation of miniballs is achieved through
use of the step number and step size control knobs with the
joystick in discharge mode so that each step or a successive number
of steps is followed by a discharge. Unless combined with an
angioplasty in the same pass, the rate of transluminal movement
during discharge is not critical. For an angioplasty, whether
thermal, cryogenic, and/or with radial projection tool-inserts, the
rate of movement is a basic ablative action exposure factor, hence,
critical. Controller-drives such as those cited above, to include,
for example, a Baldor Flex+Drive II allow control of linear stage
speed. The speed must be suitable for the specific ablative
process.
[3908] VII2h(9)(f). Ablation and Ablation and Angioplasty-Capable
Barrel-Assembly Onboard Control Panel
[3909] Devised for use independently of an airgun an ablation or
ablation and angioplasty-capable barrel-assembly is equipped with
an onboard control panel that includes the controls needed for an
ablation or angioplasty. Since the latter may include the need to
use the onboard actuators, the onboard angioplasty control panel
includes positional controls. In addition to on-off and stop action
switches, the controls required on the control panel of an ablation
or ablation and angioplasty-capable barrel-assembly include those
for:
[3910] 1. Turret-motor temperature (current).
[3911] 2. Electromagnet winding 1 temperature (current).
[3912] 3. Electromagnet winding 2 temperature (current).
[3913] 4. Turret-motor rotation (typically by means of a digital
encoder manually rotated with a knob having a pointer that moves
over an upper semicircular calibration with apical or centered
0-point and marked off in 5 degree increments to either side).
[3914] 5. Radial projection unit tool-insert 1 deployment (release,
extension, unstow)-retraction (recovery, stow).
[3915] 6. Radial projection unit tool-insert 2 (or if more than 2,
then the appliable number) deployment (release, extension,
unstow)-retraction (recovery, stow).
[3916] 7. Trap-filter (release, extension, unstow)-retraction
(recovery, stow); and possibly.
[3917] 8. An on-off switch to control a warning lamp on the control
panel that flashes when motion sensors on the muzzle-head detect
movement while the radial projection units are extended.
[3918] If, for example, the tool-inserts are used to remove
diseased tissue from alongside the lumen wall by manual
reciprocation of the muzzle-head over the lesion, then the radial
projection units are not retracted by switching on the motion
sensor circuit. The need for rotation of the muzzle-head arises
when the turret-motor heat-window may be in the form of a slot or
slit, hence directional, and because the radial projection
tool-inserts may be different and the lesion eccentric. Since more
angioplasty-capable barrel-assemblies are used manually before
insertion into and while separate from the airgun, the on-board
control panel does not have a control for the linear positioning
table, which is used for the precise intraluminal positioning
required for higher density implantation.
[3919] A vortex tube cold or hot air gun or cryogenic gas (CO.sub.2
or NO.sub.2) cartridge connected to the back end of the
barrel-assembly will usually have controls for these mounted on
those devices, as will the laser, atherectomy, or thrombectormy
devices incorporated into combination-forms as described below
under the section entitled Through-bore or combination form
Barrel-assemblies: Barrel-assemblies which Accommodate or
Incorporate Means for Ablation, Thrombectomy, Atherectomy, or
Atherotomy and/or Endoscopy. Within a given segment of about 15
centimeters, endoluminal advancement and withdrawal is accomplished
with the minimal capability barrel-assembly in the airgun using the
linear stage.
[3920] An intermediate capability barrel-assembly is generally used
for ablation or angioplasty prior to insertion into the airgun and
therefore has an on-board power and control housing mounting the
separate ablation or ablation or angioplasty control panel. A power
and control housing made to be used with the barrel-assembly
includes only the controls needed for that barrel-assembly, hence,
fewer than would be required in a fully capable barrel-assembly
control panel. A control panel on a universal barrel-assembly power
and control housing usable with any radial discharge
barrel-assembly must include the controls for the components in any
one of these.
[3921] FIG. 71b shows barrel-assembly power and control housing 163
with a graphically depicted onboard control panel such as that more
fully shown in FIG. 79, mounted at the side for illustrative
purposes; more often, for optimal operator viewability, the control
panel is mounted to the upper surface of housing 163. This may
place the control panel beside an inlet into the fluid circuit for
a drip line when present, for example. A muzzle-head positioning
and airgun discharge control panel such as that shown in FIG. 85 is
mounted in the top of the airgun cabinet to present the joystick
and control knobs at a height adjustable for the individual
operator. Preferably, the turret-motor and recovery electromagnet
controls on the barrel-assembly power and control housing are keyed
to the use of these components for ablation and/or angioplasty
according to the capability of the barrel-assembly, whereas those
on the airgun control panel pertain to these same components for
discharge-related motion control.
[3922] Made for a particular barrel-assembly rather than universal,
or meant for use with any barrel-assembly, the ablation or ablation
or angioplasty control panel shown in FIG. 79 provides controls for
setting the current to the turret-motor stator when used as a
thermal angioplasty heating element, and either of two electrical
radial projection unit thermal expansion wires used to raise
brush-type abrasion angioplasty tool-inserts into working position.
The run-ahead or downstream trap-filter is simultaneously deployed
with any tool-insert such as a side sweeper-scraper that generates
debris.
[3923] VII2h(10). Control of Transluminal Rate of Translation
[3924] Whether thermal and/or by means of radial projection unit
shaving or brush-type tool-inserts, exposure to atherectomizing
action consists of controlling the on time or the rate at which the
atherectomizing component is swept over the diseased segment. For
treating long segments suspected or confirmed to harbor vulnerable
plaque, the muzzle-head must be swept over the lumen surface at a
uniform controlled rate. When it is preferred to control the rate
more precisely than can be achieved by direct manipulation of the
barrel-assembly, a linear stage is used. The rate of of
transluminal passage is that of linear stage travel
[3925] Most controller-drive (servoamplifier) units, such as those
named in the section above entitled Control of Muzzle-head
Turret-motor Angle Within Working Arc will allow the control of
linear table motor speed regardless of the type motor used. Since
the barrel-assembly is engaged in the airgun, the controls for the
linear stage can be incorporated into the airgun control panel and
omitted from the angioplasty control panel onboard the
barrel-assembly, which includes the controls for the ablation or
ablation and angioplasty-capable barrel-assembly as an apparatus
that can be used independently of an airgun or ballistic
implantation.
[3926] VII2i. Procedure for the Extraluminal Stenting of a Smaller
Vas Using the Apparatus Described Herein
[3927] While the radial artery is too narrow to pass all but the
most basic barrel-asemblies, the decision tree and techniques
routinely attendant upon angioplasty and stenting, such as whether
to enter percutaneously through the radial, brachial, or femoral
artery, or through open exposure of the femoral, popliteal, or
brachial artery generally remain applicable. The intravenous
administration of antibiotics and antithrombogenics typically
includes 20,000 units of heparin and 81 milligrams of aspirin, 1%
lidocaine (lignocaine) injection in the puncture area.
[3928] The point of entry is a consideration in whether to use a
particular combination of fluroscopy or biplane fluroscopy,
angioscopy, intraductal ultrasound, magnetic resonance angiography,
carbon dioxide angiography, endovascular ultrasonography, spiral
computed tomography, and more recently, optical coherence
tomography (see, for example, Monroy, G. L., Won, J., Spillman, D.
R., Dsouza, R., and Boppart, S. A. 2017. "Clinical Translation of
Handheld Optical Coherence Tomography: Practical Considerations and
Recent Advancements," Journal of Biomedical Optics 22(12):1-30; Xu,
J., Song, S., Men, S., and Wang, R. K. 2017. "Long Ranging
Swept-source Optical Coherence Tomography-based Angiography
Outperforms Its Spectral-domain Counterpart in Imaging Human Skin
Microcirculations," Journal of Biomedical Optics 22(11):1-11;
Hagag, A. M., Gao, S. S., Jia, Y., and Huang, D. 2017. "Optical
Coherence Tomography Angiography: Technical Principles and Clinical
Applications in Ophthalmology," Taiwan Journal of Ophthalmology
7(3):115-129; Gao, S. S., Jia, Y., Zhang, M., Su, J. P., Liu, G.,
and 3 others 2016. "Optical Coherence Tomography Angiography,"
Investigative Ophthalmology and Visual Science 57(9): OCT27-36;
Kubo, T., Imanishi, T., Takarada, S., Kuroi, A., and nine other
authors 2007. "Assessment of Culprit Lesion Morphology in Acute
Myocardial Infarction: Ability of Optical Coherence Tomography
Compared with Intraductal Ultrasound and Coronary Angioscopy,"
Journal of the American College of Cardiology 50(10): 933-939).
[3929] Little affected are guidelines such as entry through a small
stab wound using a Number 11 scalpel; the use of a mosquito clamp
to expand the puncture site; of open arterial access to avert
embolization and control outflow arteries; and so on. Here,
however, the entry site is widened to admit the muzzle-head and
barrel-catheter. The combination of angioscopy and intraductal
ultrasound computerized processing is recommended as allowing
greater accuracy than does any external imaging technique. However,
the ability to target tissue for medication using medication
miniballs, medicated miniballs, or hypoendothelial injection
tool-inserts can significantly reduce the dose if not supplant
systemic medication administered enterally or parenterally.
[3930] In intraductal use, as the site of the lesion is approached,
the introduction and advancement of the apparatus provides
peripheral blood-grooves to serve much as the blood flow or
perfusion side-holes in catheters or, as with a balloon, deflation
to reduce the diameter, for preventing the complete cessation of
blood flow along its length. Nevertheless, by keeping operating
time to a minimum, the risks of thrombogenesis and ischemia are
reduced. To allow operative speed, the interventional airguns to be
described are designed for semiautomatic repeat action radial
discharge of from one to four or more miniball implants and
adjustability to the exact exit velocity sought without criticality
in the use of one control.
[3931] To accomplish this, the apparatus intercepts the means of
airgun propulsive force development at numerous points and
introduces a control at each. Also to avert thrombogenesis, heparin
alone or in combination with the drugs specified above is
administered until the activated clotting or coagulation time (ACT)
rises above 300, as has been routine with two guidewires and a
balloon in use. At the same time, the dosage of the platelet
blocker or anticoagulant must seek to avoid complications at the
entry site. Also routine is the application of the medication to
the tip of the catheter, here the muzzle-head of the
barrel-assembly. Preoxygenation through an oxygen mask is
recommended.
[3932] VII2j. Through-Bore, or Combination-Form,
Barrel-Assemblies
[3933] Through-bore, or combination-form, barrel-assemblies allow
cabled devices for ablation, thrombectomy, atherectomy, or
endoscopy, for example, to be interchangeably passed down through
the central channel and out the nose midprocedurally. A
barrel-assembly with built in angioscope or fiberoptic endoscope is
the same in general structure but not used and therefoe not
referred to thus. When not containing a cabled device and wetted
with heparin, such a barrel-assembly allows some blood to pass
through its side-port or ports, and down the central channel to
emerge out the nose.
[3934] VII2j(1). Incorporation of Adscititious Capabilities into
Barrel-Assemblies
[3935] A combination-form barrel-assembly is an ablation or an
ablation and angioplasty-capable barrel-assembly with a central
passageway or channel for the temporary or permanent insertion of a
cabled or a catheteric endoluminal device. The tubular passageway
is isolated and accessed through an extracorporeal side-port that
leads through a frontomedially curved section to the central axis
of the barrel-assembly where it continues forward until it ends as
a nose-hole at the front end of the muzzle-head. To create this
passageway, a combination-form barrel-assembly, as must a
barrel-assembly with built in angioscope or fiberoptic endoscope,
for example, uses an edge-discharge muzzle-head with a recovery
electromagnet pair of through-bore configuration, as depicted in
FIG. 66.
[3936] Much of what pertains to combination-form barrel-assemblies
applies equally to combination-form radial projection catheters,
addressed below in the section of like title. Atheromatous tissue
that is extensive or complex is removed with a radial projection
catheter or an ablation or angioplasty-capable barrel-assembly,
which by definition, is capable of functioning independently of an
airgun for this purpose. The end-thickness and mechanical
properties of the vascular wall for the stenting to follow must be
considered, and in some instances, it may be preferable to dispense
with angioplasty in any form as preclusive of stenting and to
directly stent.
[3937] However, when the condition is less extensive or not
present, a side-socket allows the transluminal component or
barrel-assembly to be passed through the introducer sheath but a
single time from the initiation of angioplasty to the completion of
ballistic implantation. Furthermore, when the barrel-assembly is of
a combination-form or edge-discharge type with a side-socket,
different attachments such as for atherectomy and chilling can be
interchangeably withdrawn from and advanced down the
barrel-assembly central canal midprocedurally without the need to
withdraw the barrel-assembly from its position within the lumen.
This imparts a wide range of response options for whatever
contingencies arise during the procedure.
[3938] In such function, the endoluminal barrel-assembly is a kind
of transluminal guide that sheaths about devices introduced and
withdrawn as opposed to the ensheathed configuration of a guide
wire. Exceptionally, to minimize the diameter of a combination-form
barrel-assembly, no more than one or two juxtaposed barrel-tubes
are incorporated. Shifting these to one side allows the use of a
single recovery electromagnet and the canal to pass through and out
the nose in an otherwise center-discharge configured embodiment.
For use in the circulatory system, such a barrel-assembly includes
a solenoid deployed and retracted embolic protective filter that
automatically deploys when discharge is triggered or the
turret-motor is used in oscillatory mode.
[3939] Due to the extreme constraint upon diameter imposed by the
small gauge of blood vessels and the different processes available
for treating these, reserving a pathway for luminal access is
especially valuable as well as constrained in an embodiment meant
for use in the vascular tree. Unless inducing ischemia, the cabled
or catheteric device inserted need not be withdrawn. For a
barrel-assembly of given diameter with diametrically arranged
barrel-tubes, the edge-discharge configuration, because it provides
a clear a path along the central axis, must force some reduction in
the caliber of the barrel-tubes compared to the center-discharge
type.
[3940] As seen in FIGS. 38, 39, 40, 48 49, 64, and 65, a
center-discharge muzzle-head allows positioning the recovery
electromagnets in the path of what would be the central channel in
a combination-form barrel-assembly. For use in the bloodstream,
angioplasty-capable combination-form barrel-assemblies must
additionally provide gas pressure relief channels shown as 226 in
FIGS. 48, 49, 65 and 66. In the bloodstream, the pressure of
expulsion clears blood from exit-holes 71 but is more resistant to
the expulsive gas than is the open paths provided by pressure
relief channels 226. The nose of the muzzle-head can be wetted with
heparin before use, and service catheters can inject heparin
through the barrel-tubes 74.
[3941] Even in a noncombination-form barrel-assembly, to meet these
requirements within an external diameter suited to use in most of
the arterial tree allows no more than two barrel-tubes of which one
will typically be needed for use as a service-channel For use in
the circulatory system, the increase in diameter that results from
providing a clear way to the lumen that is significantly larger in
diameter than the barrel-tube or tubes limits most
combination-forms to larger vessels. The canal can be left empty or
used to accommodate any of numerous different cabled or
catheter-based devices, to include endoscopic, intraductal
ultrasonographic, and/or operative.
[3942] The passageway or canal is thus a service channel which is
wider than a barrel-tube and exits out the nose rather than to a
side of the muzzle-head. When unoccupied, the central canal in an
ablation but not ablation or ablation and angioplasty-capable
barrel-assembly is closed at the front end by a spring-loaded
nose-cap (lid, cover). When the central canal is unoccupied, the
nose-cap prevents blood or other luminal contents from entering in
front. The distal end of an inserted cable is pushed through this
cover and into the lumen far enough to afford a clear field. When
to minimize the diameter of the barrel-assembly the barrel-tubes
are placed to the same side of the canal, the canal and nose-cap
are offset or eccentric.
[3943] Because eccentric tubes, whether barrel-tubes or an off
centered canal, whether in a center or edge-discharge configured
muzzle-head, are pliant, pass through the center bore of the
turret-motor loosely with no attachment, to attach only at their
distal extremities to the inside of the muzzle-head, resistance to
the torque generated within its limited arcuate range by the
turret-motor is slight. If the cable is smaller in diameter than
the canal, such as must be the case with a rotational atherectomy
burr as addressed below in this section, for example, the sidewise
noncompressive urging of the spring against the side of the sheath
or casing surrounding the drive shaft when the burr is in working
position serves to stabilize the cable sheath in position by
holding it against the side of the canal.
[3944] When the central channel is not fully occupied, sufficient
clearance may be available to allow blood to flow through, as
addressed below in the section entitled Flow-through
Barrel-assembly for Use in Blood Vessels. The central channel and
sheath surrounding the drive shaft must have been thoroughly wetted
with heparin. The rim of the nose-cap that is applied to the side
of the cable sheath or casing must not impede the retraction of the
cable to behind the nose-cap. If the nose-cap is metal, then its
edge must be rounded. The nose-cap must be pushed into the held
open position or released therefrom while the barrel-assembly is
extracorporeal.
[3945] The nose-hole in an ablation or ablation and
angioplasty-capable barrel-assembly is sealed off by means of a
snap-in hole-plug, as addressed A central or side canal allows the
exchange or permanent installation of almost any cabled endoluminal
(intraductal) device. A guide wire is not used. Permanent
incorporation requires few if any modifications. However,
appropriation of the canal denies its availability for additional
treatment options through the midprocedural exchange of various
cabled and catheteric devices that not only use the barrel-assembly
as a guideway, but add processes immediately applicable to
different procedures.
[3946] When not locked in the open position, the spring-loaded
nose-cap serves either to close off the distal end of the canal or
to urge and thus stabilize a cable or the sheath of a rotating
cutting tool mounted at the distal end, for example, by forcing it
against the rim of the canal. With a rotational burr, for example,
the sheath about the drive shaft of a rotating atherectomy tool is
narrower than the burr, and the canal must be wide enough for the
burr to pass through. Thus, the sheath is narrower than the canal,
so that unless held down by the spring-cap, the burr would wobble.
Due to the low torque of the high speed drive shaft, the
restorative force of the spring is minimal.
[3947] If two barrel-tubes are included in an angioplasty-capable
barrel-assembly, then the barrel-tubes are positioned with their
long axes contained within the same cross sectional semicircle or
quadrant, the canal offset as a side-canal. Hence, the
configuration for minimizing the outer diameter for use in the
vascular tree, already offset, complements the incorporation of
rotatory, such as atherectomy devices, which to allow abutment
against the luminal wall, must be offset. In most instances, the
device inserted or permanently installed will be static, such as a
laser or endoscope. The distal or front end of the inserted device
extends past the nose just enough to push aside the nose-cap and
provide a clear field of view. The central canal can also be used
to access the lumen with a catheter.
[3948] The catheter must possess a shaft of sufficient strength to
push through the spring-loaded nose-cap When the canal will not
otherwise be used, the spring loaded nose-cap can be locked open to
pass blood, the central canal preprocedurally flushed with heparin,
for example, if necessary. Plaque removal capability is added to
combination-form or edge-discharge muzzle-head type ablation or
ablation and angioplasty-capable barrel-assemblies by interchanging
atherectomy rotating burrs and lasers, for example, along the
unobstructed central canal which passes through the longitudinal
axis to end at a hole in the center of the nose. Receding into
flush relation to the surrounding outer surface of the muzzle-head
when not in use, the incorporation of radial projection unit
shaving type tool-inserts as addressed above in the section
entitled Radial Projection Unit Tool-inserts, for example, does not
increase the diameter of the muzzle-head when the tool-inserts are
not deployed.
[3949] Cabled devices include lasers and other types of ablating
(cutting), and abrading or scraping (attriting) tools, to include
low-level radio-frequency and microwave energy and rotational
atherectomy devices. For these, the central canal serves as a
guide-catheter from which one device can be withdrawn and another
inserted. Without a side-port to allow access to the central
channel, midprocedural insertion, withdrawal, or replacement of a
cabled device requires that the barrel-assembly be removed from the
airgun. With a side-port, cabled devices can be introduced and
removed midprocedurally whether the barrel-assembly is inserted in
the airgun or not. When not needed, the nose-hole can be obturated
with a plug.
[3950] A spring-loaded cap can be used to nudge a cutting tool
against the lumen wall. Another reason for using an open-ended
central canal is to minimize obstruction to the flow of blood, as
addressed below in the section entitled Flow-through
Barrel-assembly for Use in Blood Vessels. This configuration can be
incorporated into an otherwise ablation or angioplasty-incapable
barrel-assembly, but is usually incorporated into capable types.
Whenever disengaged from the airgun, the central canal is open to
the atmosphere. When one device is withdrawn and another inserted,
retraction should be done slowly to minimize the vacuum that will
draw blood up behind the retreating cable until it has been removed
exposing the central canal to the atmosphere.
[3951] Similarly, inserting another device should be done slowly to
avoid forcibly pumping blood that had been drawn up into the
central canal. Changing the relative height of the extracorporeal
portions of the apparatus and patient allows the use of hydrostatic
pressure to affect the intracorporeal pressures. The forces
involved will usually result from an orientation of the
barrel-asssembly that is retrograde to the flow of blood, and will
increase when the barrel-assembly is advanced, and reduced when
retracted. While unoccupied, the central canal can be used to allow
blood to course through the barrel-assembly and out the front
(distal) end. This is explained in the section below entitled
Flow-through Barrel-assembly for Use in Blood Vessels.
[3952] However, since a combination-form barrel-assembly is larger
in outer diameter than the equivalent noncombination-type having
the same number of barrel-tubes, gaining this capability reduces
the number of barrel-tubes that can be used in a blood vessel of
given diameter. Accordingly, this type is not for use in blood
vessels when the central canal is not used for blood flow-through
or to insert the cable of a commercial device. In other type
ductus, the nose-hole can be closed by means of a snap-in end cap
or plug. However, the flow-through advantage of the
combination-form barrel-assembly can be retained with a monobarrel
with adjacent central canal that will accommodate a laser or
rotatory burr cable, for example and still present an outer
diameter that will allow it to be used in most vessels of larger in
gauge than those with collateral circulation.
[3953] A commercial device such as a laser or a rotational burr
that is needed frequently may be permanently installed within the
central channel More often, the central channel is used to allow
various devices to be interchanged or as a service-catheter of
wider gauge than the barrel-tubes. For use in the bloodstream, to
allow some blood to flow through, the muzzle-head nose-hole is
normally left open. This also allows the interchange of different
cabled or catheteric devices without the need for midprocedural
withdrawal of the barrel-assembly as a whole rather than just the
devices inserted. For use other than in blood vessels, a torsion
spring-loaded nose-hatch (nose-cover, nose-cap) keeps the central
channel free of debris while different cabled or catheteric devices
are interchanged.
[3954] The nose-hatch is pushed open and aside by the leading end
of the device, and automatically closes as the leading end recedes
behind the hole. The device must project sufficiently forward
(distal to) the spring cover that the to avoid interference with
its mechanical or viewing performance. Except in blood vessels, the
addition of a torsion spring-loaded hatch cover or nose-cap over
the opening at the distal terminus (front end, nose) allows
different devices to be withdrawn and inserted midprocedurally;
however, the limitation placed upon the outer diameter in order to
avoid anoxia limits the use of multibarrels having radial symmetry.
Gathering barrel-tubes and exit-ports eccentrically allows the
diameter to be reduced but necessitates additional discharges to
achieve circumferential coverage.
[3955] Inserting a tube down the central canal allows lavage fluid
to be delivered or recovered axially, barrel-tubes and/or radial
projection unit perforated tool-inserts used to perform the
opposite function. Medication can be applied in the same way, with
concurrent aspiration used to take up any unwanted excess. The
relative merits of balloon angioplasty and atherectomy pertinent to
the means described herein are briefly addressed above in the
section entitled Basic Strengths and Weaknesses of Prior Art
Stenting in Vascular, Tracheobronchial, Gastrointestinal, and
Urological Interventions.
[3956] While alternatives to balloon angioplasty, such as
rotational atherectomy, have been cited as "exhibiting a "lack of
compelling trial data suggesting that the atherectomy devices offer
better outcomes in a stand-alone or even an adjunctive role,"
(Carrozza, J. P. 2006. "Coronary Complications of Coronary
Atherectomy and Excimer Laser Angioplasty," UpToDate
http://patients.uptodate.com/topic.asp?file=chd/17957), others
differ with this position (see, for example, Sandoval, Y. and
Brilakis, E. S. 2017. "The Role of Rotational Atherectomy in
Contemporary Chronic Total Occlusion Percutaneous Coronary
Intervention," Catheterization and Cardiovascular Interventions
89(5):829-831; Yu, M., Li, Y., Li, W., Lu, Z., Wei, M., and Zhang,
J. 2017. "Calcification Remodeling Index Characterized by Cardiac
CT as a Novel Parameter to Predict the Use of Rotational
Atherectomy for Coronary Intervention of Lesions with Moderate to
Severe Calcification," Korean Journal of Radiology 18(5):753-762;
Kawata, M., Kato, Y., Takada, H., Kamemura, K., Matsuura, A., and
Sakamoto, S. 2016. "Successful Rotational Atherectomy for a
Repetitive Restenosis Lesion with Underexpansion of Double Layer
Drug-eluting Stents Due to Heavily Calcified Plaque,"
Cardiovascular Intervention and Therapeutics 31(1):65-69; Tomey, M.
I., Kini, A. S., and Sharma, S. K. 2014. "Current Status of
Rotational Atherectomy," Journal of the American College of
Cardiology Cardiovascular Interventions 7(4):345-353; Yin, W. H.
2013. "Rotational Atherectomy: An Update," Journal of Geriatric
Cardiology 10(3):211-212; Fang, H. Y., Fang, C. Y., Hussein, H.,
Hsueh, S. K., Yang, C. H., and 5 others 2010. "Can a Penetration
Catheter (Tornus) Substitute [replace] Traditional Rotational
Atherectomy for Recanalizing Chronic Total Occlusions?,"
International Heart Journal 51(3):147-152; Lee, S. W., Park, S. W.,
Hong, M. K., Lee, J. H., Kim, Y. H., Moon, D. H., Oh, S. J., Lee,
C. W., Kim, J. J., and Park, S. J. 2005. "Comparison of
Angiographic and Clinical Outcomes Between Rotational Atherectomy
Versus Balloon Angioplasty Followed by Radiation Therapy with a
Rhenium-188-Mercaptoacetyltriglycine-filled Balloon in the
Treatment of Dffuse In-stent Restenosis," International Journal of
Cardiology 102(2):179-185; Sharma, S. K., Kini, A., Mehran, R.,
Lansky, A., Kobayashi, Y., and Marmur, J. D. 2004. "Randomized
Trial of Rotational Atherectomy Versus Balloon Angioplasty for
Diffuse In-stent Restenosis (ROSTER)," American Heart Journal
147(1):16-22) or do so for atherectomy as applied to a certain
patient population (see, for example, Moustapha, A., Assali, A. R.,
Sdringola, S., Vaughn, W. K., and six other authors, 2001.
"Percutaneous and Surgical Interventions for In-stent Restenosis:
Long-term Outcomes and Effect of Diabetes Mellitus," Journal of the
American College of Cardiology 37(7):1877-1882; Saland, K. E.,
Cigarroa, J. E., Lang,e R. A., and Hillis, L. D. 2000. "Rotational
Atherectomy," Cardiology in Review 8(3):174-179).
[3957] Jamming or seizing the major risk in the use of rotablation,
or rotational atherectomy (see, for example, Sulimov, D. S.,
Abdel-Wahab, M., Toelg, R., Kassner, G., Geist, V., and Richardt,
G. 2013. "Stuck Rotablator: The Nightmare of Rotational
Atherectomy," Eurolntervention 9(2):251-258; Lin, C. P., Wang, J.
H., Lee, W. L., Ku, P. M., Yin, W. H., Tsao, T. P., and Chang, C.
J. 2013. "Mechanism and Management of Burr Entrapment: A Nightmare
of Interventional Cardiologists," Journal of Geriatric Cardiology
10(3):230-234), is remediable (see, for example, Ruzsa, Z., Lux, .,
Edes, I. F., Molnar, L., and Merkely, B. 2017. "Successful Removal
of Entrapped Burr with Sheathless Guiding During Stent
Rotablation," Anatolian Journal of Cardiology 17(2):156-157;
Chiang, C. H. and Liu, S. C. 2017. "Successful Retrieval of an
Entrapped Rotablator Burr by Using a Guideliner Guiding Catheter
and a Snare," Acta Cardiologica Sinica 33(1):96-98; Kanazawa, T.,
Kadota, K., and Mitsudo, K. 2015. "Successful Rescue of Stuck
Rotablator Burr Entrapment Using a Kiwami Straight Catheter,"
Catheterization and Cardiovascular Interventions 86(5):942-945;
Tanaka, Y. and Saito, S. 2016. "Successful Retrieval of a Firmly
Stuck Rotablator Burr by Using a Modified STAR [subintimal tracking
and reentry] Technique, Catheterization and Cardiovascular
Interventions 87(4):749-756; Dandouh, Z., Abdel-Massih, T., Roule,
V., Sarkis, A., and Grollier, G. 2013. "Rotational Atherectomy as
Endovascular Haute Couture: A Road Map of Tools and Techniques for
the Interventional Management of Burr Entrapment" Journal of
Interventional Cardiology 26(6):586-595; Kosowski, M., Zimoch, W.,
Kubler, P., Wojtczak, M., Telichowski, A., and Reczuch, K. 2013.
"Percutaneous Retrieval of a Detached Rotational Atherectomy Burr,"
Post py w Kardiologii Interwencyjnej [Advances in interventional
cardiology] 9(3):301-303;; Cunnington, M. and Egred, M. 2012.
"GuideLiner, a Child-in-a-mother Catheter for Successful Retrieval
of an Entrapped Rotablator Burr," Catheterization and
Cardiovascular Interventions 79(2):271-273; Kimura, M., Shiraishi,
J., and Kohno, Y. 2011. "Successful Retrieval of an Entrapped
Rotablator Burr Using 5 Fr Guiding Catheter," Catheterization and
Cardiovascular Interventions 78(4):558-564; Sakakura, K., Ako, J.,
and Momomura, S. 2011. "Successful Removal of an Entrapped
Rotablation Burr by Extracting Drive Shaft Sheath Followed by
Balloon Dilatation," Catheterization and Cardiovascular
Interventions 78(4):567-570).
[3958] That an extraluminal stent leaves nothing in the lumen is a
significant improvement over endoluminal stents as important in
alleviating or reducing postprocedural in-stent restenosis of an
endoluminal stent and in having left nothing in the lumen that
would interfere with followup transluminal procedures which
necesssitate a clear path through the lumen. Intractable
inflammatory arterial desease can make the ability to perform a
followup transluminal procedure without hindrance critically
important (see, for example, Fournier, S., Iglesias, J. F., Zuffi,
A., Eeckhout, E., Tozzi, P., and Muller, O. 2016. "Entrapment of
Rotational Atherectomy Burrs in Freshly Implanted Stents: First
Illustration of the Rolled-Up Phenomenon," Journal of Invasive
Cardiology 28(11):E132-E133; Roy, J., Lucking, A., Strange, J., and
Sprat, J. C. 2016. "The Difference Between Success and Failure:
Subintimal Stenting Around an Occluded Stent for Treatment of a
Chronic Total Occlusion Due to In-stent Restenosis," Journal of
Invasive Cardiology 28(11):E136-E138; Sapontis, J., Christopoulos,
G., Grantham, J. A., Wyman, R. M., Alaswad, K., and 11 others 2015.
"Procedural Failure of Chronic total Occlusion Percutaneous
Coronary Intervention: Insights from a Multicenter US Registry,"
Catheterization and Cardiovascular Interventions 85(7):1115-1122;
Christopoulos, G., Karmpaliotis, D., Alaswad, K., Lombardi, W. L.,
Grantham, J. A., and 11 others 2014. "The Efficacy of "Hybrid"
Percutaneous Coronary Intervention in Chronic Total Occlusions
Caused by In-stent Restenosis: Insights from a US Multicenter
Registry," Catheterization and Cardiovascular Interventions
84(4):646-651; Ohya, H., Kyo, E., and Katoh, O. 2013. "Successful
Bypass Restenting Across the Struts of an Occluded Subintimal Stent
in Chronic Total Occlusion Using a Retrograde Approach,"
Catheterizaion and Cardiovascular Interventions
82(5):E678-E683).
[3959] For treating most plaque and restenosis, most studies find
little difference in the long-term outcome of balloon angioplasty,
cutting or scoring balloons, and rotational atherectomy. However,
hard plaque can not be passed with a conventional balloon, and even
when passable, is incapable of compressing hard calcified plaque
against the lumen wall, and is likely to cause dissections. A
fusiform (spindle or football-shaped) abrading diamond rotary
cutting or grinding burr is likely superior to alternative means
for passing highly calcified plaque, although by generating
grinding debris, poses a risk of embolization, and if preceded by
an embolic filter, poses a risk of clogging the filter and
critically restraining flow-through (see, for example, section
4d(2) entitled Ductus Wall Tumefacients and Nii, K., Tsutsumi, M.,
Maeda, H., Aikawa, H., Inoue, R., and 5 others 2016. "Comparison of
Flow Impairment during Carotid Artery Stenting Using Two Types of
Eccentric Filter Embolic Protection Devices," Neurologia
Medico-Chirurgica (Tokyo, Japan) 56(12):759-765; Iko, M., Aikawa,
H., Go, Y., Nakai, K., Tsutsumi, M., and 8 others 2014. "Treatment
Outcomes of Carotid Artery Stenting with Two Types of Distal
Protection Filter Device," SpringerPlus 3:132). Addtionally, the
cutter can unexpectedly and nondisengagably catch or seize within a
prepositioned stent, necessitating a long and life-threatening
cut-down incision to be recovered, which eventuality could never
obtain were there no stent in the lumen in the first place
(Fournier, S., Iglesias, J. F., Zuffi, A., Eeckhout, E., Tozzi, P.,
and Muller, O, 2016, Op cit.). Such risk can be averted through the
use of an excimer laser or a combination-form barrel-assembly that
incorporates such an excimer laser; however, an laser is incapable
of reducing hard calcified, or hydroxyapatite, plaque.
[3960] Use of the term `flow reversal` here does not refer to use
of the same term in conjunction with aortic regurgitation on the
diastoles due to aortic valve impairment of switching from inflow
to outflow in the use of tool-inserts but rather the deliberate
reversal of bloodflow by the interventionist to prevent the flow of
procedurally liberated atherogenic debris from passing craniad
through the internal carotid artery to cause a cerebral infarction
as described by Criado, E., Doblas, M., Fontcuberta, J., Orgaz, A.,
and Flores, A. 2004, cited below.
[3961] Transluminal or transcervical angioplasty of the carotids
does appear to result in reduced incidents of thromboembolism
induced ischemic stroke with blood flow reversal, which is
compatible with the use of the transluminal devices to include
barrel-assemblies, combination-form barrel-assemblies, and radial
projection catheters described herein (see, for example,
Paraskevas, K. I. and Veith, F. J. 2017. "Transcervical Access,
Reversal of Flow and Mesh-covered Stents: New Options in the
Armamentarium of Carotid Artery Stenting," World Journal of
Cardiology 9(5):416-421; Cully, E. H., Trapp, B. M., and Vonesh, M.
J. 2017. Single Access Flow-reversal Catheter Devices and Methods,
U.S. Pat. No. 9,668,743; Kwolek, C. J., Jaff, M. R., Leal, J. I.,
Hopkins, L. N., Shah, R. M., and 3 others 2015. "Results of the
ROADSTER [Safety and Efficacy Study for Reverse Flow Used During
Carotid Artery Stenting Procedure] Multicenter Trial of
Transcarotid Stenting with Dynamic Flow Reversal," Journal of
Vascular Surgery 62(5):1227-1234; Clair, D. G., Hopkins, L. N.,
Mehta, M., Kasirajan, K., Schermerhorn, M. and 5 others with 19
collaborators 2011. "Neuroprotection During Carotid Artery Stenting
Using the GORE [W.L. Gore and Associates Incorporated, Newark,
Del.] Flow Reversal System: 30-day Outcomes in the EMPiRE Clinical
Study," Catheterization and Cardiovascular Interventions
77(3):420-429; Kelso, R. and Clair, D. G. 2008. "Flow Reversal for
Cerebral Protection in Carotid Artery Stenting: A Review,"
Perspectives in Vascular Surgery and Endovascular Therapy
20(3):282-290; Parodi, J. 2008. "Commentary on "Flow Reversal for
Cerebral Protection in Carotid Artery Stenting: A Review,"
Perspectives in Vascular Surgery and Endovascular Therapy
20(3):291-292; Criado, E., Doblas, M., Fontcuberta, J., Orgaz, A.,
Flores, A., and 5 others 2004. "Transcervical Carotid Stenting with
Internal Carotid Artery Flow Reversal: Feasibility and Preliminary
Results," Journal of Vascular Surgery 40(3):476-483; Criado, E.,
Doblas, M., Fontcuberta, J., Orgaz, A., and Flores, A. 2004.
"Transcervical Carotid Artery Angioplasty and Stenting with Carotid
Flow Reversal: Surgical Technique," Annals of Vascular Surgery
18(2):257-261).
[3962] VII2j(2). Accommodation of Rotational Ablating or
Atherectomizing Side-Cutting Devices in Combination-Forms
[3963] Through-bore or combination-form barrel-assemblies and
radial projection catheters, as addressed below in the section of
like title, must allow the use of rotational or linear side-cutting
devices and allow these to be retracted into the central channel
when not in use so that the combination-form device can itself
remain stationary within the lumen. In an artery, rotating burrs
and razors are used to perform an atherectomy (see, for example,
Fornell, D. 2010. "New Tools to Debulk Lesions: Combo
Cutting/Aspiration Catheter and Laser Systems Offer New Atherectomy
Choices," Diagnostic and Interventional Cardiology 50(1):16-17),
and comparable devices to perform an ablation in other type ductus
can be anticipated. Means for bringing the cutting end into
functional alignment against the lumen wall are therefore necessary
both in arteries and in the airway, where the entry of debris is
not a problem, and in the gastrointestinal tract, for example,
where it is.
[3964] A barrel-assembly with an eccentric bore allows a cabled
rotational device to abut against the lumen wall in substantially
parallel relation to remove accreted or diseased tissue. However,
an eccentric bore also precludes rotation of the muzzle-head by the
turret-motor, and depending upon the diameter of its cable, limits
if not precludes the incorporation of radial projection units over
the periphery in the sector over the segment occupied by the
rotational device. By the same token, the use of a central bore
requires a mechanism to urge the cutter sideways into functional
contact with the lumen wall. A snap-in spring-loaded nose-cap to
cover over the nose-hole when the central channel or bore is
unoccupied is addressed above in the section entitled Capabilities
of Different Type Barrel-assemblies.
[3965] When the rotational or linear device is passed through the
bore and up to or out through the nose-hole, the push-through or
snap-in spring-loaded nose-cap is pushed open and aside. Such a
spring-loaded nose-cap can be used to push against the sheath
urging the cutter into contact with the lumen wall with the force
set by the spring. When the cutter is retracted, the spring-loaded
cap closes behind it. For the purpose of closing off the nose-hole
to prevent the entry of debris, a surround extending wiper fingers,
likewise addressed above in the section entitled Capabilities of
Different Type Barrel-assemblies, is equally effective as a
nose-cap and far better at wiping down and keeping out debris as
the working end of the cutting device is retracted behind it.
[3966] In the gut, for example, a spring-loaded nose-cap can serve
favorably both to urge the cutting tool against the lumen wall and
to close off the nose-hole when the tool is retracted. The
inseparability of sidewise urging and closure means, however, that
a second instrument such as an endoscope will also be deflected as
well as obstructed unless fully protruded. Moreover, in an artery,
a patent central channel allows some blood to flow through, and in
the airway, some air. For most applications, urging against the
lumen wall, cleaning upon closure, and sealing off of the central
channel as the cutter recedes must be separated.
[3967] A spring-loaded arm mounted off to a side of the nose-hole
rather than a cap does not close off the nose-hole to block the
lumen. However, attached as is a cap to the muzzle-head rather than
to the inserted device, unless the extent to which the tool can be
advanced is limited, the arm will cause the cutter to veer more
aside (abluminally, radially outward) as it is advanced and will
remain even after the tool has been withdrawn to obstruct the view
through an endoscope used after and not just together with the
cutting tool. A stop or detent about the sheath of the cutting
tool, which can take the form of an annular depression caught by
the free end of the spring-arm.
[3968] When keeping debris out is an object, a rubbery surround
that extends wiper fingers toward the center where the tips of the
free ends meet is more effective, while a spring arm attached to
the muzzle-head can be used at the same time to urge the cutter
into the proper working angle relative to the lumen wall. Another
problem with a cap is that when it is open and the barrel-assembly
or radial projection catheter is advanced, even provided with an
elastomeric surround, the edge could gouge or incise the lumen
wall. A spring attached to the sheath of a cutting tool with one
arm compressed by the central channel while contained therein will
serve to urge the distal end of the sheath to the side against the
lumen wall, and fastened to the specific tool rather than to the
muzzle-head, is not left to interfere with the use of any other
tool.
[3969] More specifically, in a radially symmetrical barrel-assembly
intended for general use, the eccentricity required to use a
rotational cutting tool is obtained by cinch-clamping a bent spring
steel or torsion spring about the sheath of the rotational burr or
razor so that when the rotational device is passed through the bore
as a guide catheter and forward out through the nose, the bore
continues to compress and the arms of the spring flat until the
upper arm passes through the nose, and free to close, urges the
sheath of the device toward the lumen wall. The distance to which
the distal end of the cutting tool can be extended past the
nose-hole and its consequent abluminal reach are set by the level
along the tool shaft at which the spring is fastened and is limited
by a lug stopped by a nose-hole detent.
[3970] The detent consists of a slight inward ledge rim about the
nose-hole that catches a projection on the spring and thus stops
the sheath from advancing further. The spring must be clamped about
the sheath at a distance sufficiently proximal to the nose to allow
the cutting head to achieve a working angle relative to the lumen
wall. The proximal portion of the cable-mounted spring thus remains
within the bore and sets the limit to forward and abluminal
extension. For use in the gut, for example, such a spring is
combined with a fingered surround for wipe-down and closure. Upon
retraction, the fingers first sweep over the surface of the spring,
then the rotating tool, and once the tool is retracted, close off
the nose-hole to debris. The bore is therefore clean allowing
insertion of another cabled device.
[3971] VII2j(3). Types of Combination-Form Barrel-Assemblies
[3972] Combination-form barrel-assemblies are ablation-capable or
ablation and angioplasty-capable, such classification not further
divided according to the number of barrel-tubes or incorporation of
different cabled or catheter devices. Angioplasty-capable
barrel-assemblies are always capable of ablation, but due to the
sever limitation on size and requirement for pressure relief, the
reverse need not be true. Ablation-capable barrel-assemblies are
generally larger, do not need to alot space for gas pressure
diversion channels, or shift barrel-tubes to the same side of the
canal to achieve a smaller cross section. These therefore tend to
use the edge-discharge configuration shown in FIG. 66.
[3973] Distinction based upon structure as edge or center-discharge
is substantially pertinent only to angioplasty-capable
barrel-assemblies. The nose-holes of ablation, ablation and
angioplasty-capable barrel-assemblies, and combination-form radial
projection catheters when the latter two are used in the
bloodstream are not covered. This allows some blood to flow through
and eliminates a lid or hatch opened to the front that even with an
elastomeric surround risks incisions when advanced. The torsion
spring closed hole-cover or lid has a base made like an electronic
chassis hole-plug with prongs about the circumference that hold the
lid in the nose-hole by radial restorative force.
[3974] VII2j(4). Forward-Directed Clearing (Ablation and/or
Angioplasty) Means for Integration into the Muzzle-Head
[3975] The rearward extension of the muzzle-head imparts a
longitudinal aligning effect, and the barrel-catheter with internal
components is made sufficiently stiff to track with no buckling
without the need for a guide or `buddy` wire, the muzzle assembly
itself effectively a fixed wire, as opposed to an over the-wire
device. Any catheter-based means for the removal of plaque can be
integrated into the muzzle-head at the front end so that the
implantation of the miniballs can follow immediately upon the
removal of plaque. However, a preferable means would not
necessitate either thermal insulation or extension in length of the
muzzle-head as to deny depth of implantation access, as addressed
above in the section entitled Factors that Affect Muzzle-head
Nosing Length or Reach, Steerability, and Trackability.
[3976] While the longitudinal elongation exerts a canal-aligning
effect that reduces the risk for an exposed sharp rotational
atherectomy cutter or burr at the front end to go off-course
producing furrows if not perforations, so long as the burr remains
exposed, this would always loom as a possibility. Thus, to use a
rotational burr, the muzzle-head would have to be extended forward
in length so that the burr could be held within a recess at the
front end until used. While such extension would consist of only
about six millimeters, this length could prove significant if
moving down the vascular tree, the lumen diameter had become
sufficiently narrow to require stretching and the likelihood of
dissection if advancement were to continue.
[3977] Incorporating an excimer laser substantially avoids the risk
of embolism, hence, the need for a protective device such as an
embolic filter, but is unsuited for reducing the hardest calcified
plaque, is capable of dissections and perforations, and is
associated with more frequent restenosis (Liu, W., Zhang, Y., Yu,
C. M., Ji, Q. W., Cai, M., Zhao, Y. X., and Zhou, Y. J. 2015.
"Current Understanding of Coronary Artery Calcification," Journal
of Geriatric Cardiology 12(6):668-675; Bittl, J. A., Chew, D. P.,
Topol, E. J., Kong, D. F., and Califf, R. M. 2004. "Meta-analysis
of Randomized Trials of Percutaneous Transluminal Coronary
Angioplasty versus Atherectomy, Cutting Balloon Atherotomy, or
Laser Angioplasty," Journal of the American College of Cardiology
43(6): 936-942).
[3978] Incorporation of a rotational atherectomy burr makes it
possible to cut a path through the hardest mineralized obstructions
and thus affords a critical capability over alternative devices.
Conventional or balloon-based thermal and cryogenic devices
introduce temperature and thus dimensional instability that to
protect against erratic performance would necessitate the
incorporation of insulation for which space is lacking. In the
coronary arteries, for example, placing balloon based devices in
tandem with the muzzle-head would untenably deny depth of
access.
[3979] The least obtrusive and disruptive means of ablation
suitable for integration into the muzzle-head are ultraviolet
xenon-chlorine excited dimer or `excimer` lasers and continuous
wave neodymium yttrium aluminum garnet or Nd:YAG, and carbon
dioxide or CO.sub.2 lasers. Nevertheless, demanding an increase in
the outer diameter of the muzzle-head, incorporating a laser does
reduce the lumen diameter, hence, the extent of the vascular tree
that may be accessed with any one muzzle-head. For this reason, the
incorporation of a laser into a barrel-assembly relates more to
those with one or a few barrels. In contrast to thermal and
cryogenic balloons, the optical fibers connected to the console
leading to the small diameter probe tip are mechanically and
thermally passive.
[3980] VII2j(5). Barrel-Assembly with Built in Excimer Laser
[3981] While various mid-course divisions or divergences and
confluences of laser fiber optics would allow the fibers to be
coursed about other components, incorporation of an excimer laser
into a barrel-assembly is advantageously and preferably obtained
without the need to significantly modify an off-the-shelf laser
catheter. Laser atherectomy actually cavitates and vaporizes all
but highly calcified plaque rather than merely compressing plaque
as does balloon angioplasty, which is, however, accomplished more
quickly. In the present context, however, the radial projection
unit side-sweeping capability, the laser in variable sequences,
and--when the lumen diameter is the same or smaller than that of
the muzzle-head--coordinated use of the muzzle-head much as a
balloon, allow greater speed of tissue reduction and removal than
any of these components alone.
[3982] All catheter-based procedures can induce abrupt closure by
spasm. Other problems encountered with lasers alone, notably the
inducement of spasm and promotion of fibrin deposition, are
similarly moderated by immediate follow-up with implants
(spherules, miniballs) that have been medicated to counteract these
complications. Since both laser atherectomy and ballistic
implantation can induce such responses, making antispasmodic and
antiplatelet or anticoagulant-coated miniballs routinely available
is advisable. Referring now to FIG. 67, shown is the front or
distal end of an edge-discharge muzzle-head for a combination-form
barrel-assembly which incorporates a pulsed ultraviolet
photo-ablation excimer laser having optical fibers, each consisting
of a core, cladding, buffer, and containing sheath or catheter,
with distal end centered in the nose.
[3983] Additionally incorporated adjacent to the laser is an
embolic filter, which is controlled by switching to automatically
deploy when a radial projection unit is used and disabled whenever
the laser is in use. To prevent plaque that extends to the center
of the lumen from being undercut closer to the lumen wall and freed
as pieces toward the lumen axis to pass down the bloodstream
intact, the distal ends of the optical fibers close to the surface
of the muzzle-head can be made to follow the outer contour of the
muzzle-head slightly bent toward the central axis, while the outer
fibers are directed straight ahead. The muzzle-head of a
barrel-assembly that incorporates a laser must have a nosing that
places the distal ends of the optical fibers at a distance from the
front end and the plaque to be fully effective.
[3984] The optical fibers are omitted from positions about the
circumference that would cause the fibers to course over
blood-grooves, blood-tunnels, the entry ledges before the doors on
the traction electromagnet chambers, the muzzle-ports, and
side-scaper ablators. Remote rotation of the muzzle-spindle by
means of a swivel or turret-motor requires that the optical fibers
be cut at the level of the rotary joint between the distal end of
the motor and proximal end of the muzzle-spindle. However, since
rotation is no part of the plaque removal process but rather part
of the stenting function which does not commence until plaque
removal has been completed, the proximal and distal portions of
each fiber do not move in relation to one another until their use
has ended.
[3985] To minimize losses to refraction and scatterting at the
interface where the portions meet, the segments of the fibers are
made to interface as flush as will not interfere with the use of
the swivel or turret-motor. For atherectomy by means of
photo-ablation, the xenon-chlorine laser is set to a wavelength of
308 nanometers with a rate of pulsation ranging between 25 and 80
repetitions per minute. The fiber optics in the barrel-assembly are
connected to an excimer laser control console, such as the
Spectranetics CVX-300.RTM. excimer laser system. Since the laser
vaporizes plaque laying directly to the front of the distal ends of
the fibers, better coverage is obtained when the fibers are more
radially distributed about the nose of the muzzle-head.
[3986] Generally, the use of a laser to destroy atherosclerotic
material and hinder subsequent hyperplasia can be potentiated when
the target tissue has been primed through the preprocedural
administration and accumulation in the target tissue of a
photosensitive drug (see, for example, Jain, M., Zellweger, M.,
Wagnieres, G., van den Bergh, H., Cook, S., and Giraud, M. N. 2017.
"Photodynamic Therapy for the Treatment of Atherosclerotic Plaque:
Lost in Translation?," Cardiovascular Therapy 35(2); Chou, T. M.,
Woodburn, K. W., Cheong, W. F., Lacy, S. A., Sudhir, K., Adelman,
D. C., and Wahr, D. 2002. "Photodynamic Therapy: Applications in
Atherosclerotic Vascular Disease with Motexafin Lutetium,"
Catheterization and Cardiovascular Interventions 57(3):387-394;
Chen, Z., Woodburn, K. W., Shi, C., Adelman, D. C., Rogers, C., and
Simon, D. I. 2001. "Photodynamic Therapy with Motexafin Lutetium
Induces Redox-sensitive Apoptosis of Vascular Cells,"
Arteriosclerosis, Thrombosis, and Vascular Biology 21(5):759-764;
Rockson, S. G., Lorenz, D. P., Cheong, W. F., and Woodburn, K. W.
2000. "Photoangioplasty: An Emerging Clinical Cardiovascular Role
for Photodynamic Therapy," Circulation 102(5):591-596) to reduce
the restrained atheroma and any restenosing tissue by the time the
stent has been absorbed. Impermanent, absorbable stents are
unsuited to interdictory use on an extended basis, such sites
largely identifiable, as addressed in the section above entitled
Comparison of Extraluminal with Endoluminal, or Conventional,
Stenting.
[3987] VII2j(6). Barrel-Assembly with Exchangeable or Built in
Rotational Atherectomy Burr
[3988] As addressed above in the section entitled Radial projection
unit tool-inserts, a radial projection unit tool-insert with
diamond particle covered cutting surface that is reciprocated at
high speed by the turret-motor in oscillatory mode can abrade
mineralized plaque. However, a rotational burr can achieve a faster
cutting rate, making expedient the incorporability of such a device
into a combination-form barrel-assembly. A rotational atherectomy
burr is best inserted temporarily so that it can be interchanged
with alternative cabled devices for viewing or treatment. The canal
itself service as the guideway, a guide wire not used. If step up
burr technique is to be used, then the canal must accommodate the
widest of the burrs to be used. The addition of medication to the
drive shaft coolant and administration of medication, such as
abciximab, aspirin, calcium channel blockers, heparin, and so on,
are unremarkable.
[3989] The use of cabled and catheteric devices with
combination-form barrel-assemblies is addressed above in the
section entitled Incorporation of Adscititious Capabilities into
Barrel-assemblies. The burr is inserted into the barrel-assembly
through a side-socket and fed through the canal until the tip of
the burr is positioned just inside the nose, which position is
marked on the casing or sheath before use. The tethering is that of
the commercial device. Alternative use of the barrel-assembly can
precede use of the burr, which to use is advanced through the
barrel-assembly to a second mark on the casing at which point one
arm of a spring mounted to the the outer sheath of the cable exits
urging the burr against the lumen wall. The burr can be freely
deployed or retracted (withdrawn, stowed) at any time the
barrel-assembly is in use.
[3990] VII2j(7). Flow-Through Barrel-Assembly for Use in Blood
Vessels
[3991] Any edge-discharge type barrel-assembly can be furnished
with a patent central channel as a combination-form barrel-assembly
for use in the bloodstream. Provided the central canal is
unoccupied or affords sufficient clearance, a combination-form
barrel-assembly can allow blood to course through it. When
antegrade, flow is through side-ports equivalent to the side-holes
in conventional catheters at the surface along the distal
barrel-catheter that lead through frontomedially directed
tunnel-tubes past any intervening barrel-tubes or pressurized gas
diversion channel into the central channel or bore and out the
nose-hole. When retrograde, blood enters through the nose-hole and
exits out the side-ports. The pressure of flow depends upon the
blood pressure and cross-sectional area over this path.
[3992] See also the section below entitled Flow-through Bore in
Combination form Barrel-assemblies and Combination form Radial
Projection Catheters Used in Blood Vessels. More specifically, the
central canal communicates at an acute angle with the surrounding
lumen through short tubes over the intracorporeal length, each
leading to an operning on the outer surface of the barrel-catheter.
The use of multiple side-holes makes it possible to use the same
barrel-assembly over a range of intraluminal lengths; otherwise, a
single such channel, placed for the intracorporeal length actually
involved, which is slightly easier to work with, is used. The holes
and central canal should be dimensioned and configured so that flow
through those distal does not detract from the rate of inflow into
those more proximal and impede the flowrate down the central
canal.
[3993] So long as the central canal is unoccupied, the elliptical
entry and exit portals and short length of the connecting tubes
expedite the flow-through of blood. Inserting a cable through the
central canal closes off these side-tubes or passages. The
peribarrel space surrounding each barrel-tube and therefore, the
ability of the barrel-assembly to prevent the expulsion of gas into
the bloodstream is unaffected whether the central canal is or is
not occupied. Coagulation on the barrel-assembly is avoided by
submerging the barrel-assembly in an anticoagulant, such as
heparin-saline, acid-citrate-dextrose, or
ethylenediaminetetraacetic acid solution, then, dipping the
nose-hole in the solution, using a bulb or syringe pipette to draw
solution up through the service canal until solution begins to
spill from the the side or entry portal most distad.
[3994] The bulb or syringe having been left attached to its
proximal end, the entry of gas into the bloodstream is avoided by
then inserting the barrel-assembly through the introducer sheath, a
fingertip used to prevent the solution from spilling out through
the distal entry portal. As this first and subsequent (more
proximal) entry portals enter, the bulb or syringe is used to draw
the Ringer's solution and blood up to the next entry portal until
the intracorporeal length is reached. The insertion and withdrawal
of interchangeable cabled devices with the barrel-assembly
remaining endouminal is addressed below in the section entitled
Incorporation of Supplementar Capabilities
[3995] VII2j(8). Widely Applicable Barrel-Assembly
[3996] The versatility of a side-socketed barrel-assembly is
addressed in the section above entitled Concept of the Extraluminal
Stent and the Means for Its Placement. A side-socketed
combination-form, or edge-discharge, barrel-assembly is versatile
in accepting commercial cabled auxiliary devices and attachments,
making it widely adaptable at added cost. Combination-form
barrel-assemblies always have a side-socket that includes a portal
for admitting the cable of various viewing, atherectomy and other
cabled devices. One or more cabled device is inserted through the
central bore or channel to or past the muzzle-head nose hole.
[3997] In order to allow the central canal to accommodate either
the cable of a commercial atherectomy device or a cooling catheter
during discharge without the need to withdraw the barrel-assembly
at any time from the commencement of the angioplasty to completion
of discharge, the need for a nose-window (nose `heat-window) must
be eliminated, since the distal end of the barrel-assembly is
inaccessible from the outside. If not the concurrent attachment of
a nose `heat-window installed on a temporary basis, then a cooling
catheter requires a coolant inflatable balloon to project out of
the front of the central canal. Since the balloon is distal to the
muzzle-ports, chilling to stabilize the target tissue would then
follow rather than precede discharge, limiting discharge to
transluminal advancement.
[3998] The various cables and catheters used as hoses to be fed
down the central canal of a wide use barrel-assembly must have a
tick mark at the proximal end to show exactly to what depth the
device is to be snaked (fed, advanced) down the central canal, and
must also be guided to the proper ending position. This requires
but a flared central hole (aperture) in each centering device to
act as a funnel. An annulus with front flange or detent projections
to prevent further forward insertion at the front opening of the
central canal or the rear (proximal edge) of the nose-window if
attached engages the distal end of the cooling catheter thus
centering it at the correct distance from its proximal surface. If
the source of cold air is a vortex tube cold air gun, switching to
the hot outlet allows the quick return to body temperature.
[3999] Antithrombogenic medication should be administered when
using elevated or lowered temperatures in the bloodstream. The
highly localized introduction of implants that consist purely of
medication is more quickly and less traumatically accomplished by
means of ballistic discharge than by inserting stays one at a time
through an incision. The lack of an incision through which the
ductus might be approached from outside or extraluminally does,
however, require that if used, cold be delivered endoluminally. In
an artery of sufficient luminal diameter, this is accomplished with
an ablation or ablation and angioplasty-capable barrel-assembly
equipped with a fluid radial projection system. The use of a
snap-in hole-plug when it is preferred to keep the nose-hole closed
is addressed above in the section entitled Types of
Barrel-assemblies.
[4000] VIII. Radial Projection Catheters
[4001] VIII1. Types of Radial Projection Catheters.
[4002] Eliminating radial projection units from the
barrel-assembly, especially fluid units from the muzzle-head, makes
possible a significant reduction in gauge and stiffness that allows
a more navigable barrel-assembly to pass through narrower ductus or
reach farther down into the vascular tree. Relegating projection
units to a removable sheath (sleeve, mantle) of matching size with
its own power and control housing which can be slid over or removed
from the barrel-assembly at any time also also allows the
muzzle-head to be made shorter, imparting greater steerability that
makes it possible to pass sharper curves. Lacking a ballistic
component, a separate radial projection catheter is not a
barrel-assembly. When used alone or as primary with other
catheteric devices inserted through the central bore, it is
referred to as radial projection assembly.
[4003] Very narrow ductus require relegation to a separate
noncombinable radial projection catheter without an available
central bore referred to as a simple radial projection catheter.
Abutment of a much narrower projection catheter against the lumen
wall is by 1. Ensheathing the intraluminal projection catheter
within one of larger diameter, 2. Using an external magnet to draw
a ferromagnetic cord that has been built into or is temporarily
inserted into the barrel-catheter or the projection catheter, or 3.
Using push-arm blanks mounted or not mounted on a scissors-lift
platform, as addressed above in the section entitled Extended
Projection Scissors Lift-platform Mechanism.
[4004] All radial projection catheters, to include
combination-forms made for combined use with a barrel-assembly,
radial projection catheter of smaller diameter, or a cabled device,
include a power and control housing and can be used independently.
If provided with side-ports, the unoccupied bore can be used to
allow some blood to flow through. Ablation or ablation and
angioplasty-capable Barrel-assemblies which ensheath a
barrel-assembly as ballistic component within a combination-form
radial projection catheter as a supplementary or adjunct peripheral
component relative to that in the muzzle-head constitute joint or
divisible, (with two components, bipartite or duplex) ablation or
ablation and angioplasty-capable barrel-assemblies. In any such
combination, only the peripheral component is augmented, but the
endoluminal device is rendered bipartite or duplex.
[4005] A conventional guide wire, simple radial projection
catheter, or a barrel-assembly can be ensheathed within a
combination-form barrel-assembly having a distal through-bore or
edge-discharge type muzzle-head. Rather than a distal muzzle-head,
a combination-form barrel-assembly can include exit ports at
another level or at different levels along its length, thus
incorporating the nominally ballistic component within the
peripheral component. Supplementation of the ballistic component in
the muzzle-head by ensheathment to obtain a larger diameter for
discharge or to increase the caliber of the miniballs, making the
ballistic the peripheral component, is discounted as nonessential
and introducing complications such as proximal spillage from the
lumen of the central component requiring plugging before insertion
in the airgun, for example.
[4006] The use of interchangeable combination-form radial
projection catheters with the same central component means that the
clogging of even several fluid circuits during aspiration can be
responded to by exchanging only the peripheral or outer component.
This avoids the need to withdraw and retrack the central component,
which is left in place as a guide wire. Any number of outer
projection catheters, each differently equipped or differing in
outer diameter, can be exchanged (replaced, `swapped`). When fully
ensheathed, the rear of the catheter housing fits flush to the
front of the barrel-assembly housing, which is slid proximally
(backward) to allow the projection catheter to slide
separately.
[4007] When a combination-form radial projection catheter of larger
diameter is slid over or withdrawn from one of smaller diameter,
the power and control housings of the intervening projection
catheter is slid off the proximal end of the projection catheter.
As shown in FIG. 71, in a duplex ablation or ablation and
angioplasty-capable barrel-assembly, the length as well as
concentrically matched sizes mean that the power and control
housing of the ensheathed barrel-assembly and that of the outer
projection catheter juxtapose flush in ganged relation. When
advanced and withdrawn with the aid of the linkage shown in FIG.
78, the encircling projection catheter with its housing moves
forward with the barrel-catheter, the barrel-assembly housing held
in position by the connecting arm that extends from the base of the
linear positioning stage.
[4008] Since only the intracorporeal portion of the duplex is
doubled decreasing its flexibility, the need for the extension
linkage to prevent sagging of the extracorporeal length remains.
The power and control housing of an ensheathed radial projection
catheter is unused and removed by being slid off its proximal or
rear end. The housing of an ensheathed barrel-assembly is proximal
and juxtaposed against the rear of the outermost combination-form
projection catheter housing when fully ensheathed. Removal is by
sliding the housing off the proximal end of the intervening
projection catheter as addressed below in the section entitled
Slidable Radial Projection Catheter Power and Control Housing.
[4009] Ensheathment must always take trackability into account, so
that one or another of these concentrically fitted catheteric
devices can be partially withdrawn when moving through a curve, for
example. For economy, small diameter minimally ablation or ablation
and angioplasty-capable barrel-assemblies can be made fully
ablation or ablation and angioplasty-capable by sliding the
projection catheter over the barrel-assembly when disengaged from
the airgun. However, since a minimally capable barrel-assembly
lacks a power and control housing, the functions normally
controlled from the housing must be incorporated into the housing
of the projection catheter despite the fact that for clarity and to
reduce human error, it is always preferred to mount controls to the
component to which the controls pertain.
[4010] Larger diameter embodiments can be made integral or entire
with radial projection units incorporated into the muzzle-head
and/or about the barrel-catheter without the need for
supplementation through use of a sheath. Because lumen diameters
limit the components that can be incorporated into a radial
projection catheter, simple radial projection injection catheters
are usually limited to a fiberoptic endoscope and hemitoroidal
heat-window at the nose. Simple radial projection catheters with
unit lift-shafts configured to allow the engagement of tool-inserts
for performing an ablation or an angioplasty have a punch or
plunger solenoid deployed and stowed embolic filter as, and if
space will allow, a fiberoptic endoscope, centered in the
hemitoroidal heat-window surrounding it at the nose.
[4011] To expedite crossing curves, the radial projection catheter
can be held back while the muzzle-head is pushed forward. Numerous
interchangeable combination-form radial projection catheters that
match the barrel-catheter of a given barrel-assembly in diameter,
can differ widely in outer diameter and the electrical and fluid
circuits each contains. Since such immediate adaptation to changes
in lumen diameter can use projection catheters of a prescribed
flexibility and fitted with tool-inserts of the same or different
kinds of tool-inserts, difference in diameter resulting from
lesions that protrude into the lumen, for example, can be responded
to by exchanging projection catheters as appropriate.
[4012] This makes possible wide variability in the flexibility,
diameter, and capabilities of a barrel-assembly and the specific
matching projection catheter combined at a given time; using the
barrel-assembly as a guide wire introduced and advanced to a
treatment site first, combination-form projection catheters of
different diameters and capabilities can be exchanged as the
diameter and condition of the lumen changes. Whether a
barrel-assembly is at the center, in lumina of sufficient diameter,
combination-form projection catheters with bores matched to receive
narrower projection catheters allow the successive withdrawal of
the outer projection catheter as the lumen becomes gradually
narrower.
[4013] That is, since the more central projection catheters are in
effect prepositioned, the number of introductions through the entry
wound is reduced; however, in the vascular tree, introducing the
outer projection catheter not prefilled thus makes the central
channel available for blood to pass. To preclude human error that
would result in the use of an ablative tool-insert in an injection
catheter that lacked effective means for intercepting potentially
embolic debris, for example, these different tool-inserts and made
in slightly different sizes or with keys to prevent insertion in an
unintended catheter.
[4014] For these reasons, radial projection units not needed to
eject a lubricant into the lumen or inject lesions on initial
approach, and fluid units in particular, are consigned to a
separate sheath that can be slid over a barrel-assembly or cabled
device such as a separate fiberoptic endoscope or thrombectomy
cutter at any time before of after the device has been introduced
into the body. Radial projection catheters of either kind are
self-contained, internally powered, and controlled independently of
the barrel-assembly. A simple or noncombination-form radial
projection catheter is used independently of a barrel-assembly to
ablate, angioplasty, or eject a fluid substance into the lumen or
inject the substance into the lumen wall.
[4015] This allows a smaller outer diameter than a
combination-form, which must accommodate cabled devices through a
central channel or through and through bore. Simple projection
catheter that must achieve an outer diameter that is too small to
allow the incorporation of both a scope and an embolic filter are
differentiated as injection or ablation in type, the former
including a viewing device such as a fiberoptic endoscope, the
latter an embolic filter at the nose center. A combination-form
differs from a simple radial projection catheter in having a
central channel, or bore, which allows it to be slid over the
barrel-catheter of a barrel-assembly or pass a cabled device up to
or through the nose-hole.
[4016] When unoccupied or not too fully occupied by any diagnostic
or therapeutic instrument and the nose-hole at the distal end of
the projection catheter is not plugged by means of a snap-in
nose-cap, the central channel may afford sufficient clearance for
some blood to pass to or from a side-port. The constraints on
diameter are, however, such as to limit any practical ischemia
averting consequences to only larger vessels. Omitting a ballistic
component, a noncombination-form radial projection catheter can
deliver a level of functionality to lumina too narrow or tightly
curved to admit a barrel-assembly equipped with the same radial
projection units. In less narrow ductus, it can also incorporate
fluid radial projection units and perform endoluminal procedures
such as ablation and injection independently of a
barrel-assembly.
[4017] Combination-form radial projection catheters with radial
projection units that do not accept tool-inserts of ablation size
or keying and marked for injection only can be made especially
narrow. Not generating debris, it relies upon the nose heat-window
and omits an embolic filter at the nose to incorporate a built in
angioscope or fiberoptic endoscope for precise injection. By
contrast, a combination-form radial projection catheter can be used
separately or to add functionality to a barrel-assembly. It can be
slid over the barrel-catheter of the barrel-assembly used as a kind
of guide wire, or removed as necessary whether the barrel-assembly
is extracorporeal or endoluminal.
[4018] VIII2. Simple, or Noncombination-Form, Radial Projection
Catheters
[4019] Simple radial projection catheters differ from
combination-form or through-bore radial projection catheters in
that a central channel if any is too small and unavailable for
insertion of a cabled device or the barrel-catheter of a
barrel-assembly. One exception is that a fine fiberoptic endoscope
may be permanently fixed in position along the longitudinal central
axis. As a matter of definition, however, embodiments with a
central channel large enough to accommodate a cabled device such as
an endoscope, laser, or rotational atherectomizer, for example, are
combination-form radial projection catheters. The capabilities of a
simple radial projection catheter can include the ejection of
medication or other therapeutic substances to coat the lumen wall,
infuse a vein, inject a fluid therapeutic substance into the lumen
wall, thermoplasty, and ablate with cutting (shaving) or abrading
tools.
[4020] A radial projection catheter equipped with fluid units can
additionally cryoplasty, sequentially or concurrently irrigate and
aspirate using water or another therapeutic solution, or inject or
eject fluid substances intermittently or continuously in any
amount. All radial projection catheters whether simple or
combination-form have a proximal power and control housing, which
unlike that of a barrel-assembly, is not slidable. Simple, or
noncombination-form, radial projection catheters may have a central
channel for wires of fluid lines. A separate or simple
(noncombination-form) projection catheter that incorporates only
electrically controlled radial projection units can be made
narrower and more flexible than one with one or more fluid
circuits.
[4021] Using side-looking injectors, or if the small diameter and
strength of the ductus allow, emitter-irrigator-aspirator fluid
tool-inserts, numerous procedures possible with a simple radial
projection catheter need have no relation to ballistic implantation
or stenting of any kind. When, for example, the need for miniballs
consisting of medication or a sclerosant, for example, can be
satisfied by injection tool-inserts, the use of a radial projection
catheter allows the procedure to be completed with a single luminal
entry. Larger ductus such as those of the gastrointestinal tract
and the trachea and bronchi allow the use of combination-form
radial projection catheter-ensheathed barrel-assemblies and
combination-form barrel-assembly-ensheathed cabled devices such as
a laser.
[4022] However, when a lumen requiring an ablation or an
angioplasty prior to stenting is too narrow to admit even a
muzzle-head that includes both the necessary radial projection
units and the number of barrel-tubes desired, a simple radial
projection catheter can be used first, followed by a narrow
barrel-assembly having a radial discharge monobarrel muzzle-head,
for example. To do so does, however, lose the advantage of both
preparatory therapy and implantation with single entry. To achieve
the narrowest diameter rules out a central channel Simple radial
projection catheters that lack the tool-inserts to act as side
pushing arms use the channel to incorporate a ferromagnetic cord
that facilitates abutment of the tool-insert faces against the
lumen wall with the aid of an external electromagnet.
[4023] Varying the cord as solid or braided and the material and
thickness of the solid cord or each braid allows adjusting catheter
flexibility for the best balance between trackability and
sufficient stiffness to prevent injury to the lumen wall when the
external magnet is used. For use in the arterial tree, a simple or
noncombination-form that is used to deliver medication and not used
to perform an atherectomy usually includes a nichrome coil heated
hemitoroidal dome configured heat-window at the nose with the
convex surface directed downstream, or distad.
[4024] When switched on, the heat-window sears the caps of
vulnerable plaques and burns the potentially embolizing contents as
the muzzle-head passes. Centered within this annular heat-window,
the hole in the nose is commonly occupied by the distal end of a
fine fiberoptic endoscope. Because radial projection units in
independent circuits assigned to different radial angles are
situated about its circumference, the turret-motor of a ballistic
component is not required.
[4025] VIII3. Through-Bore, or Combination-Form, Radial Projection
Catheters
[4026] A combination-form radial projection catheter has a
through-and-through central axial channel or bore for retaining, or
for conveying in the manner of a guide catheter, a cabled device
such as a laser, an endoscope, or diameter allowing, more than one
such device. Using the barrel-catheter of the barrel-assembly in
the manner of a guide wire, the combination-form radial projection
catheter is slid leading (distal) end first over the proximal end
of the barrel-catheter. Because the power and control housing
hand-grip of an ablation or ablation and angioplasty-capable
barrel-assembly can be slid off the proximal end of the
barrel-catheter, a radial projection catheter of matching size can
be added at any time before or after a fully ablation or ablation
and angioplasty-capable barrel-assembly has been introduced into
the body.
[4027] When not used independently, a combination-form radial
projection catheter slips over the ensheathed device such as a
barrel-assembly. However, a combination-form radial projection
catheter can be used apart from the ensheathed device with or
without a nose-hole plug. For a barrel-assembly, steerability,
trackability, and navigability in general are expedited by allowing
reduction in the longitudinal extent of the radial projection units
at the sides of the muzzle-head, which can thus be shorter. With
the aid of an external magnet to aid in steering the muzzle-head,
high pliancy and a short muzzle-head make it possible to navigate
through tight curves. However, the same barrel-assembly in a less
restrictive ductus would gain considerable capability through the
addition of the projection catheter.
[4028] Because the radii of curvature and strength properties of
different type ductus vary, multiple combination-form radial
projection catheters with different degrees of flexibility can be
provided for use with an ablation or ablation and
angioplasty-capable barrel-assembly of given size. Structural
factors that also affect flexibilty are addressed below in the
section entitled Fabrication of Radial Projection Catheters. For a
given outer diameter, the material or materials and wall
thicknesses, even when kept uniform as preferred, is variable as
well, so that the flexibility of a radial projection catheter
noncombination-form or combination-form can be specified over a
wide range.
[4029] Reduced rotatability due to an increase in diameter with the
addition of a combination-form radial projection catheter is
compensated for by providing the distal end of the projection
catheter with forward directed dentate keys about the rim which fit
into corresponding recesses at the back of the muzzle-head when
aligned. These are kept medial, or flush against the sides of the
barrel-catheter to prevent chiseling into the lumen wall. Rotation
is with the the power and control housings of the barrel-assembly
and projection catheter juxtaposed or ganged and used as a single
handle, rotating the combination as a unit. The combination-form
projection catheter can be withdrawn to any extent from just enough
to free the muzzle-head for easier sidewise bending, to
extracorporeal.
[4030] It can remain stationary while the more steerable and
trackable barrel-assembly when unsheathed is advanced, and once the
muzzle-head has reached the treatment site, again slid over the
barrel-catheter to any distance up to the rear of the muzzle-head
to add function. When not, a narrow gauged radial discharge
barrel-assembly must also be used. Such limitation due to the
narrow gauge of the ductus is simply given. For precise
transluminal positioning, a radial projection catheter, like an
ablation or ablation and angioplasty-capable barrel-assembly, can
be inserted into a linear positioning stage-mounted airgun as
addressed below in the section entitled Linear Positioning Stage or
Table Airgun Mount.
[4031] Also like a combination-form barrel-assembly, a
combination-form radial projection catheter can be designed to
allow blood to flow through the central channel when unoccupied.
The nose-hole is used but the side-port through which the cabled
device is led is extracorporeal, so that distal or intracorporeal
(endolumina,l intraductal, endovascular,) side-port or ports are
required. A simple radial projection catheter consists of a pliant
tube with radial projection units facing radially outward about the
circumference over the intracorporeal length. The units are powered
and controlled within the self-contained apparatus from a hand-grip
enclosure at the rear or proximal end.
[4032] When a cabled device is not installed in the lumen, the tube
is closed off at the distal or far end by a convex snap-in
nose-plug as addressed in the next section entitled Through-bore,
or Combination form, Radial Projection Catheters. With cabled
device such as a laser or endoscope permanently installed in the
lumen, the apparatus is a combination-form radial projection
catheter, likewise addressed in the next section. Combination-form
radial projection catheters that represent the peripheral component
of a bipartite or duplex ablation or ablation and
angioplasty-capable barrel-assembly and/or which can also be slid
over a simple radial projection catheter must not only match the
device to be ensheathed in size but in providing cutouts to avoid
obstructing openings such as side-ports and blood-tunnels in the
subjacent device.
[4033] Tick marks or rings etched into the outside of the
barrel-catheter indicate that the openings in the ensheathed or
subjacent barrel-assembly or projection catheter are in alignment
with the cutout or a plurality thereof. Providing multiple cutouts
at intervals allows the ensheathed device to be advanced or the
projection catheter partially withdrawn without obstructing the
openings. With either a combination-form radial projection catheter
for use in the bloodstream or a combination-form ablation or
ablation and angioplasty-capable barrel-assembly, a snap-in
hole-plug that is dome-shaped but otherwise similar to those used
in an electronic chassis is used to close off the nose-hole when
the central channel or bore is to remain unoccupied. With the
device intracorporeal, the plug is not removable. In the
circulatory system, this prevents blood from passing through the
central channel.
[4034] The device must be withdrawn, the plug removed, and the
device reintroduced. A nose-cap is not used in the circulatory
system because it prevents blood from passing when closed,
obstructs viewing devices not projected past (beyond, distal to) it
on the side on the opened cap side, and risks incisions. Except in
the circulatory system, when the central channel of either an
ablation (but not angioplasty) -capable combination-form
barrel-assembly or a combination-form radial projection catheter
must be kept free of debris and the flow through of blood is not
preferred, a spring-loaded nose-cap is used that is swung open to a
side by a cabled device as it pushes past the nose-cap and closes
as the cabled devices recede behind the nose-cap.
[4035] The polymer material lining the central channel is
nonthrombogenic and wetted with a an anticoagulant, such as
heparin, or fibrinolytic, such as streptokinase, prior to
insertion. A service catheter coated with this solution is inserted
through the channel prior to entry into the vessel and whenever one
cabled or catheteric device is exchanged for another. Neither the
snap-in hole-plug nor spring-loaded nose-cap covers are removable
with the device intracorporeal. The space available does not allow
for withdrawal of a cap into the muzzle-head or the components to
accomplish opening and closing by remote control. A nose-cap that
can be snapped in when desired according to the procedure can avert
some of these problems, but is not removable with the
combination-form barrel-assembly or the projection catheter
intraluminal.
[4036] Use of a spring-loaded nose-cap, to include one that can be
snapped in, solely to nudge a rotational cutter sideways is
objectionable in configuring the muzzle-head for only one of
several different cabled devices when this could interfere with the
use of other devices. For these reasons, the central channel is
usually left without a nose-cap, sidewise urging of a rotational
cutter accomplished by a spring device attached to the cutter
without affecting the muzzle-head or other cabled devices that
might be used. When the gauge (diameter) of the lumen allows use of
a combination-form radial projection catheter with a
barrel-assembly inserted, the oscillatory mode of the turret-motor
can be used to reinforce the action of ablation shaving
tool-inserts, for example.
[4037] For use in a blood vessel, the barrel-assembly must
incorporate an embolic filter, as addressed above in the section
entitled Trap-filter in Angioplasty-incapable Radial Discharge
Muzzle-heads for Use in the Vascular Tree. Devices so equipped can
be used with the central channel occupied or vacant. A minimally
ablation or ablation and angioplasty-capable barrel-assembly is not
intended for use independently of an airgun, and lacking a housing,
poses no obstruction to use thus. The separability between
barrel-assembly and projection catheter allows the barrel-assembly,
while narrow in gauge and more pliant for better steerability and
trackability, to be advanced to the treatment site first, and once
placed, act as a `guide wire` for the radial projection catheter
that can add radial projection units to extend over the entire
intracorporeal (endoluminal) length.
[4038] Steerability of the barrel-assembly may be implemented with
the aid of an external electromagnet, by limiting the muzzle-head
in length thus constraining the neck area available for electrical
radial projection units, and by avoiding fluid units that require
fluid lines and thus reduce flexibility. When the barrel-assembly
is a tight fit, a combination-form radial projection catheter will
not be usable. However, the same barrel-assembly in a less
restrictive ductus would gain considerable capability through the
overlayment of the projection catheter. Because the radii of
curvature and strength properties of different type ductus vary,
multiple combination-form radial projection catheters with
different degrees of flexibility are made for use with an ablation
or ablation and angioplasty-capable barrel-assembly of given
size.
[4039] In addition to the factors that affect flexibility addressed
below in the section entitled Fabrication of Radial Projection
Catheters, the projection catheter can include any number and type
of fluid lines and units whether electrical or fluid operated.
Fluid operated radial projection units are not incorporated into
any but the largest barrel-assemblies. Size-matched or paired
barrel-assemblies and radial projection catheters are in effect
Barrel-assemblies which to optimize endoluminal entry and
functional range are made in two parts. This requires that the
power and control housing of the barrel-assembly be disconnected.
When the housing is reconnected, the housing of the radial
projection catheter and that of the barrel-assembly are position in
ganged relation.
[4040] The power and controls of each device, which can be used
independently, are juxtaposed, so that patching between the two in
order to share functions is unnecessary, When the barrel-assembly
is introduced first, electrical/fluid system-neutral or spring
released ejection tool-inserts in the muzzle-head can further
contribute to trackability by releasing a lubricant with or without
use of the oscillatory mode of the turret-motor. The radial
projection catheter can likewise emit a lubricant whether slid over
the barrel-assembly before or after introduction. Combining a
combination form radial projection catheter with a combination-form
barrel-assembly in this way is practicable only in larger
ductus.
[4041] Fluoropolymers low in friction but higher in stiffness,
these requirements can be met, for example, through the use of a
highly pliant polymer which is given an outer coating of
polytetrafluoroethylene or made as a coextrusion to produce a
similar result. Further to minimize the risk of injury, when the
muzzle-head incorporates electrically operated radial projection
units with electrical/fluid system-neutral (spring-released,
spring-discharged) syringe emitters loaded therein, these can be
used with syringe ejection tool-inserts, or ejectors, to release a
lubricant such as ACS Microslide.RTM., Medtronic Enhance.RTM., Bard
Pro/Pel.RTM. or Hydro/Pel.RTM., or Cordis SLX into the lumen to
reduce clinging and the risk of injury during rotation and when
passing curves.
[4042] This is limited, however, to the muzzle-head, whereas a
radial projection catheter, simple or combination-form, can extend
the emission of a lubricant throughout its length. Due to the
minimal gauge attainable, such application in the arterial tree is
limited. Because ablation or ablation and angioplasty-capable
barrel-assemblies and radial projection catheters have numerous
capabilities independently of one another, optimal functionality is
obtained by making these in matched sets designed for use together
according to gauge. Rather than abbreviating either for use as an
attachment for the other, the paired apparatuses are made to be
fully usable as independent but well matched when used
together.
[4043] Rather than to incorporate controls in either to support the
other as an attachment, the power and control housing, or
battery-pack and hand-grip, with control panel of each contains the
full complement of controls necessary to support its respective
apparatus as independent. When combined, each retains its
respective power and control housing with control panel. Combining
the two thus combines the entire functionality of either. When the
two are combined, retaining the full range of capabilities of
either apparatus is not only necessary, but combination
significantly multiplies the capabilities of the pair as such. When
the combination-form radial projection catheter is introduced
first, it can be used as a guide catheter for different cabled
devices midprocedurally, and when a cabled device is introduced
first, the cabled device can serve as a guide wire for the
combination-form radial projection catheter.
[4044] However, due to the larger diameter of the muzzle-head, a
barrel-assembly must be introduced first and thereafter jacketed
with a radial projection catheter; only a disproportionately large
combination-form radial projection catheter usable as a guide
catheter for a barrel-assembly. The radial projection catheter can
then be withdrawn before or together with the barrel-assembly. For
the treatment of larger lumina such as the gastrointestinal tract,
a combination-form radial projection catheter or a combination-form
barrel-assembly can be used as a guide catheter for narrow
catheteric and cabled devices. A combination-form barrel-assembly
can be introduced first, used as a guide catheter, and as a guide
wire for a radial projection catheter.
[4045] The catheteric and cabled devices can be freely interchanged
in any sequence, and the radial projection catheter can be
withdrawn before the barrel-assembly, but the muzzle-head will
prevent the barrel-assembly from being withdrawn without the
projection catheter. A combination-form radial projection catheter
is effectively an ablation or ablation and angioplasty-capable
combination-form barrel-assembly with the same outward conformation
but without a ballistic component. As with a combination-form
barrel-assembly, the device, such as a laser or endoscope, can be
installed permanently or a lumen provided for accepting
interchangeable cabled devices.
[4046] Such interchangeability can have much value, because it
allows cabled devices to be changed not just midprocedurally but
while the catheter remains intracorporeal. The pliancy, hence,
trackability of the catheter will vary with each different type
cabled device or with none in the lumen. Withdrawing the cabled
device without transluminal movement of the catheter can therefore
allow the catheter to be passed through a curve before the cabled
device is reinserted. To reduce the risk of incisions or
perforations, the radial projection catheter must present a leading
edge that is blunted, an outer surface that is slippery, and be
highly pliant.
[4047] VIII4. Slidable Projection Catheter Power and Control
Housing
[4048] To allow ensheathment and the ability to maintain a
consistent distance from the entry wound, the power and control
housing hand-grips of barrel-assemblies and projection catheters
ensheathable within a combination-form radial projection catheter
of larger diameter must be slidable and removable by being slid off
the proximal end of the barrel-catheter. The housing thus functions
in the same manner as one in an angioplasty-capable
barrel-assembly, as addressed above in the section entitled
Slidable Ablation or ablation and angioplasty-capable
Barrel-assembly Power and Control Housing.
[4049] VIII5. Fabrication of Radial Projection Catheters
[4050] One cross section profile suitable for an extrusion to be
made into a radial projection catheter has circular or rectangular
lumina in the number required positioned at equal angles about the
central longitudinal axis. To expedite extrusion, longitudinally
separating, inner, and outer walls are the same in thickness. This
profile makes possible the narrowest projection catheters and is
preferred when only electrical projection units, which demand less
diameter than fluid units, are to be included. Combination-form
radial projection catheters are generally larger in diameter and
more readily accommodate fluid circuits. Non-combination and
combination-form radial projection catheters differ only in that
the central channel or lumen in the latter is large enough to
accommodate a cabled device such as an endoscope or laser, for
example.
[4051] Radial projection catheters are made of custom extruded
multiluminal tubing. For more problem free production, the wall
thicknesses, to include the inner, outer, and those separating the
lumina, which can have any shape as seen in cross section, are kept
the same. Since the outer surface of the radial projection catheter
can be coated or shrink-wrapped in polytetrafluoroethylene film,
the underlying tubing is chemically isolated and can therefore
consist of any pliant material or materials, even those allergenic
on direct contact. The extrusion used being the difference, the two
types are fabricated alike. A narrow projection catheter for use in
blood vessels usually includes a hemipherical heat-window at the
nose with convexity or dome directed forward (downstream, distad)
to thermoplasty any vulnerable plaque and burn any debris that
rupture of the plaque cap would liberate.
[4052] An extrusion profile that better accommodates fluid circuits
consists of a central and two radially outward concentric lumina.
The center and outer lumina are connected by radial arms that are
longitudinally extended. These running partitions or walls divide
the outer lumina into arcuate passageways. When the diameter is
less restrictive, the simple projection catheter includes a central
lumen leading distally up to the hole at the center of a
hemitoroidal heat-window with convexity or dome directed forward.
In a small diameter embodiment to be used solely for injection, for
example, and not expected to generate more debris than the
heat-window can destroy, the central lumen and hole are used to
hold a fiberoptic endoscope or other aid to viewing.
[4053] If a projection catheter that is limited to a small diameter
is to be used with ablative or abrasive tool-inserts that generate
debris, the central lumen and hole are used to hold an embolic
filter silo with deployment and stowing solenoid as that shown in
FIG. 50. A still less restrictive diameter allows the central lumen
and hole in the nose-window to house both a fiberoptic endoscope
and embolic filter side by side. Using the kind of extrusion
preferred for an electrical or a fluid circuit as appropriate, the
radial holes for the lift-shafts are drilled into the side of the
extrusion while it is stabilized in a grooved jig of applicable
diameter which is clamped down onto the table of a drill press and
advanced or positioned sidewise by means of a slide screw.
[4054] For for low volume production, sidewise positioning of the
jig to align the catheter to the drill bit is manual by rotating
the slide screw, while for higher volumes, the jig is advanced by
means of a linear positioning stage driven by a point to point or
discrete (noncontinuous path) numerically controlled stepper motor.
Square lift-shafts are drilled with a Reuleaux triangular bit in an
eccentric or floating chuck such as produced by the Watts Brothers
Tool Works, Wilmerding, Pennsylvania. For precise machining,
catheters made of rubbery material that resist drilling are first
frozen. Whether electrical or fluid, the circuit is preassembled by
connection in series into a string or chain of projection units
with intervening conductors.
[4055] Exceptionally, the receiving lift-shaft holes and units for
insertion into these can have different cross sections. The string
is pushed through its lumen so that each unit is vertically aligned
to its respective hole and the rear or proximal end of each
conductor projects past or overextends the rear end of the
catheter. A rod of the diameter required to bring the upper edges
of the units flush to the outer surface of the catheter having a
front end tapered to expedite sliding under each unit is then
pushed through the lumen successively driving each unit up into its
respective hole wherein it is retained by friction fit. Any
difficulty in sliding the front end of the lifting rod beneath a
unit is dealt with by lifting the unit from the outside by means of
a pin with a nonallergenic pressure sensitive adhesive at its
tip.
[4056] The nose heat-window, fiberoptic endoscope, embolic filter,
and/or other viewing or treatment device, and a ferromagnetic cord
to expedite steering and abuttment against the lumen wall by means
of a hand held electromagnet are preassembled into a joint holder
which is inserted at the forward or distal end of the projection
catheter, the conductor pushed down through the lumen first, then
the holder at the distal end pushed into a premachined opening in
which the holder is retained by friction fit. The rear or proximal
end of the projection catheter ends in a terminal plate with the
contact or fluid port for each circuit.
[4057] The terminal or end plate, which has a hole with surrounding
toroidal electrical contact for each conductor, is then heated so
that the toroid surrounded hole for each conductor is sufficiently
expanded to allow the projecting ends of the conductors to be
passed through its respective hole. The end plate is pushed over
the projecting ends of the conductors and flush against the rear
end of the catheter. Cooling can be accelerated by means of a
vortex cold air gun, for example. Upon cooling, the conductors are
locked into their respective holes and the end plate held flush
against the rear of the catheter by contraction seizure at room
temperature.
[4058] The excess conductors are snipped off flush to the rear
faces of the holes. The end plate is now a plug which fits into the
corresponding socket at the front of the power and control housing
hand grip. Since circumferentially discretionary control requires
that each circuit be separately controllable, it is important that
each conductor be connected to the correct contact in the socket.
Proper alignment of the plug in the socket is obtained by aligning
a tick mark or scratch on the side of the rear end of the catheter
with another at the edge of the socket.
[4059] IX. Side-Ports
[4060] IX1. Proximal Side-ports in Angioplasty-Capable
Barrel-Assemblies
[4061] Barrel-assemblies for use in the vascular tree must
incorporate discharge gas pressure diversion channels that vent to
the exterior to prevent the introduction of gas into the
bloodstream. Venting through a slit membrane of suitable resilience
at the proximal end of the barrel-catheter would release the gas
into the airtight chamber of the airgun. Thus, a side-port
(side-hole) in an extracorporeal segment (a segment outside the
patient, proximal to the entry wound) of the barrel-catheter, with
a one-way outlet valve serves as discharge gas pressure relief
vent. The side-port, similar to a side-hole in a conventional
catheter, communicates with the peribarrel space (qv.) or gas
pressure diversion channel inside the barrel-catheter.
[4062] IX2. Proximal Side-Ports in Combination-Form
Barrel-Assemblies and Combination-Form Radial Projection
Catheters
[4063] Generally larger in diameter than a vent and leading via a
frontomedially directed passageway into the central channel or
(qv.) bore of a combination-form (qv.) barrel-assembly or a
combination-form radial projection catheter, a side-port can serve
to pass a cabled device or devices, such as a fiberoptic endoscope
or a laser, into the central channel so that it can be moved up to
or through the nose or front end. Especially with respect to such
use, a side-port should not be confused with a side-socket (qv.)
which, also limited to placement in an extracorporeal (extraductal,
proximal) segment or on the side of the combination-form
barrel-assembly or radial projection catheter power and control
housing, is an electrical and/or fluid line connector, that is, a
receptacle.
[4064] IX3. Distal Side-Ports in Combination-Form Barrel-Assemblies
and Combination-Form Radial Projection Catheters
[4065] In an intracorporeal (endovascular, intraductal, distal)
segment of a combination-form barrel-assembly or a combination-form
radial projection catheter facing antegrade, or with the flow of
blood, a side-port allows blood to flow through the unoccupied bore
or central channel (qv.) and out the nose or front end. More
specifically, the blood flows into the side-port, thence through an
anteromedial tunnel-tube that isolates blood or other ductus
contents from gases past any intervening barrel-tube into the
central channel, and is thus essentially equivalent to a side hole
in an existing catheter.
[4066] X. Steering and Emergency Recovery of Implants with the Aid
of an External (Extracorporeal) Electromagnet
[4067] X1. Use of an External Electromagnet to Assist in Steering
or in Freeing the Muzzle-Head
[4068] Conventional hand-held electromagnets are portative, not
tractive, that is, made to carry magnetically susceptible matter
when in direct contact, not to draw susceptible matter over a
distance. Such magnets can generally exert tractive force out to a
distance of about 3 inches (76.2). This is generally sufficient for
a separation function such as lifting away susceptible debris from
parts moving past the magnet or magnets suspended above a conveyor
belt, but inadequate to extract a susceptible object from within
the body where interventing tissue will resist extraction and the
depth into tissue may be considerably greater than 3 inches.
[4069] There are three ways to overcome this limitation, the first
described below in section X2c, entitled Stereotactic Arrest and
Extraction of a Circulating, Dangerously Mispositioned, or
Embolizing Miniball. Essentially, the B.sub.0 magnet of a magnetic
resonance imaging machine is connected by a silver wire cable to a
hand-held probe. In most instances, this greater tractive force is
more dependable and available in any center where intravascular
procedures are routinely performed. The second method is the use of
a custom made floor machine-independent hand-held electromagnet
with a core or armature of pure iron or fused iron-silicon (Si--Fe)
crystals wound about with insulated silver wire. Spherule detention
pertains both to emergency and nonemergency conditions.
[4070] Si--Fe crystals are readily and economically obtained and
more susceptible to magnetic force than other materials (Stoller,
H. M., Austin, F. E., and Seeger, E. W. 1920. Small Motors,
Transformers, Electromagnets, Chicago, Ill.: American Technical
Society, page 21 on (not to be confused with the same authors'
Small Motors, Transformers, Electromagnets: A Practical
Presentation of Design and Construction Data for Small Motors,
Small Low-and High-tension Transformers, Electromagnets, and
Induction Coils; Haus, H. A., and Melcher, J. R. 1989.
Electromagnetic Fields and Energy, Englewood Cliffs, N.J.:
Prentice-Hall, also available at Massachusetts Institute of
Technology OpenCourseWare http://ocw.mit.edu, Chapter 9; see also
Wu, Q., He, W., Liu, H. L., Ye, J., Zhang, X. Q., Yang, H. T.,
Chen, Z. Y., and Cheng, Z. H. 2013. "Tuning Magnetic Anisotropies
of Fe films on Si(111) Substrate via Direction Variation of Heating
Current," Scientific Reports 3:1547; Ye, J., He, W., Wu, Q., Liu,
H. L., Zhang, X. Q., Chen, Z. Y., and Cheng, Z. H. 2013.
"Determination of Magnetic Anisotropy Constants in Fe Ultrathin
Film on Vicinal Si(111) by Anisotropic Magnetoresistance,"
Scientific Reports 3:2148; Chang, H. W., Tsay, J. S., Hung, Y. C.,
Chan, W. Y., Su, W. B., Chang, C. S., and Yao, Y. D. 2011.
"Investigation of Magnetic Properties and Microstructure of
Ultrathin Co Films Grown on Si(111)-7.times.7 Surface," Journal of
Nanoscience and Nanotechnology 11(3):2696-2699; Sorbello, F.,
Hughes, G. M., Lejcek, P., Heard, P. J., and Flewitt, P. E. 2009.
"Preparation of Location-specific Thin Foils from Fe-3% Si Bi- and
Tri-crystals for Examination in a FEG-STEM [field emission gun
scanning transmission electron microscope]," Ultramicroscopy
109(2):147-153; Andreev, A. V., Yoshii, S., Kuz'min, M. D., de
Boer, F. R., Kindo, K., and Hagiwara, M. 2009. "A High-field
Magnetization Study of a Nd(2)Fe(14)Si(3) Single Crystal," Journal
of Physics. Condensed Matter 21(14):146005; Hashi, S., Ishiyama,
K., Arai, K. I., Kawasaki, M., and Yamashiro, Y. 1996. "Study on
the Deformation of 3% Si--Fe Single Crystal with Magnetic Field
Being Deviated from [001]," Institute of Electrical and Electronics
Engineers Transactions on Magnetics 32(5):4848-4850; Tanaka, T.,
Takahashi, M., Wakiyama, T., Yamato, M., and Watanabe, D. 1985.
"Magnetic Properties of 6.5 wt % Si--Fe Alloy Single Crystal with
Phase Separation," Institute of Electrical and Electronics
Engineers Translation Journal on Magnetics in Japan
1(5):548-549).
[4071] When a magnetic resonance imaging machine is not available,
the use of such a magnet necessitates the incorporation of
iron-silicon crystals in implants to be drawn or barrel-assembly
muzzle-head to be rendered steerable by application of external
tractive force. An electromagnet is used to allow adjustment of the
field strength to the minimum essential to steer the muzzle-head or
to stabilize it in position by abutment against the luminal
wall.
[4072] The muzzle-head recovery tractive electromagnets are
themselves magnetically susceptible and make possible the use of an
external electromagnet to steer the barrel-assembly (see also
Mathieu, J-B., Soulez, G., Beaudoin, G., Felfoul, O., Chanu, A.,
and Martel, S. 2008. "Steering and Tracking of Magnetic Catheters
Using MRI Systems," Abstract No. 76, Journal of Vascular and
Interventional Radiology 19(2):S31-S31; Tamaz, S., Chanu, A.,
Mathieu, J.-B., Gourdeau, R., and Martel, S. 2008. "Real-time
MRI-based Control of a Ferromagnetic Core for Endovascular
Navigation," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Engineering 55(7):1854-1863; Chanu A.,
Felfoul O., Beaudoin G., and Martel S. 2008 "Adapting the Software
Platform of MRI for the Real-time Navigation of Endovascular
Untethered Ferromagnetic Devices," Magnetic Resonance in Medicine
59(6):1287-1297; Grady, M. S., Howard, M. A. 3rd, Dacey, R. G. Jr.,
Blume, W., Lawson, M., Werp, P., and Ritter, R. C. 2000.
"Experimental Study of the Magnetic Stereotaxis System for Catheter
Manipulation within the Brain," Journal of Neurosurgery
93(2):282-288). Radial projection catheters and combination-form
radial projection catheters accept a snap-in nose-cap containing
ferrous metal for the purpose.
[4073] Recently a promising third category of means for
magnetically steering nanotherapeutics to a nidus or lesion deep
within the body has emerged and continues under intensive research
(Mahajan, K. D., Ruan, G., Dorcena, C. J., Vieira, G., Nabar, G.,
and 5 others 2016. "Steering Microtubule Shuttle Transport with
Dynamically Controlled Magnetic Fields," Royal Society of Chemistry
Nanoscale Issue 16; Mohammed, L., Ragab, D., and Gomaa, H. 2016.
"Bioactivity of Hybrid Polymeric Magnetic Nanoparticles and Their
Applications in Drug Delivery," Current Pharmaceutical Design
22(22):3332-3352; Nacev, A., Weinberg, I. N., Stepanov, P. Y.,
Kupfer, S., Mair, L. O., and 4 others 2015. "Dynamic Inversion
Enables External Magnets to Concentrate Ferromagnetic Rods to a
Central Target," American Chemical Society Nano Letters
15(1):359-364; Estelrich, J., Escribano, E., Queralt, J., and
Busquets, M. A. 2015. "Iron Oxide Nanoparticles for
Magnetically-Guided and Magnetically-Responsive Drug Delivery,"
International Journal of Molecular Sciences 16(4):8070-8101;
Mardinoglu, A. and Cregg, P. J. 2015. "Modelling the Effect of
SPION [superparamagnetic iron oxide nanoparticles] Size in a Stent
Assisted Magnetic Drug Targeting System with Interparticle
Interactions," Scientific World Journal 2015:618658; Laurent, S.,
Saei, A. A., Behzadi, S., Panahifar, A., and Mahmoudi, M. 2014.
"Superparamagnetic Iron Oxide Nanoparticles for Delivery of
Therapeutic Agents: Opportunities and Challenges," Expert Opinion
on Drug Delivery 11(9):1449-1470; Kumar, A., Jena, P. K., Behera,
S., Lockey, R. F., Mohapatra, S., and Mohapatra, S. 2010.
"Multifunctional Magnetic Nanoparticles for Targeted Delivery,"
Nanomedicine 6(1):64-69; Shapiro, B. 2009. "Towards Dynamic Control
of Magnetic Fields to Focus Magnetic Carriers to Targets Deep
Inside the Body," Journal of Magnetism and Magnetic Materials
321(10):1594-1599; Polyak, B.and Friedman, G. 2009. "Magnetic
Targeting for Site-specific Drug Delivery: Applications and
Clinical Potential," Expert Opinion on Drug Delivery 6(1):53-70;
Chen, H., Kaminski, M. D., Pytel, P., Macdonald, L., and Rosengart,
A. J. 2008. "Capture of Magnetic Carriers within Large Arteries
Using External Magnetic Fields," Journal of Drug Targeting
16(4):262-268).
[4074] Yet another method for cavitating or breakdown lyzing of
microemboli, which applies only to miniballs consisting of a
magnetically susceptible nanoparticulate embedded in a reducible
matrix, is microtripsy (see, for example, Zhang, X., Jin, L.,
Vlaisavljevich, E., Owens, G. E., Gurm, H. S., Cain, C. A., and Xu,
Z. 2015. "Noninvasive Thrombolysis Using Microtripsy: A Parameter
Study," Institute of Electrical and Electronics Engineers
Transaction on Ultrasonics, Ferroelectrics, and Frequency Control
62(12):2092-2105; Zhang, X., Owens, G. E., Gurm, H. S., Ding, Y.,
Cain, C. A., and Xu, Z. 2015. "Noninvasive Thrombolysis Using
Histotripsy Beyond the Intrinsic Threshold (Microtripsy),"
Institute of Electrical and Electronics Engineers Transaction on
Ultrasonics, Ferroelectrics, and Frequency Control 62(7):1342-1355'
Lin, K. W., Kim, Y., Maxwell, A. D., Wang, T. Y., Hall, T. L., Xu,
Z., Fowlkes, J. B., and Cain, C. A. 2014. "Histotripsy Beyond the
Intrinsic Cavitation Threshold Using Very Short Ultrasound Pulses:
Microtripsy," Institute of Electrical and Electronics Engineers
Transaction on Ultrasonics, Ferroelectrics, and Frequency Control
61(2):251-265).
[4075] While the small electromagnets within stent-jackets and
impasse-jackets used to draw spherules into the intima are wound
with silver wire about an iron core, these are generally proximate
enough as not to necessitate further modification. Stabilization in
this way rarely pertains to discharge but rather to imaging whether
of an onboard fiberoptic endoscope, for example, or an external
viewing device. An external tractive or separator-type
electromagnet with a core or armature as a narrow tapered, or
subulate, probe ending in a narrow tip is used to focus the
magnetic force reducing the risk of disrupting any implants. The
same device can be used to free the muzzle-head were it to cling to
the lumen wall. Using an external magnet or a tool-insert, a
clinging muzzle-head can be pushed aside for a syringe ejection
tool-insert to release a lubricant into the gap. The turret-motor
is then used to rotate or if necessary, to oscillate and thus free
the muzzle-head.
[4076] X2. Use of an External Electromagnet to Assist in Mishap
Recovery
[4077] X2a. Interception and Recovery of a Miniball Entering the
Circulation
[4078] Potentially embolizing miniballs released into the
circulation midprocedurally are seized with the aid of the recovery
electromagnets in the muzzle-head, a run-ahead embolic filter, an
external electromagnet, and an impasse-jacket prepositioned
downstream of the implantation site, which latter can be left in
place indefinitely to prevent embolization postprocedurally.
Deterrents to embolization by due to the loss of a miniball in the
circulation are incorporated into barrel-assemblies and
stent-jackets as well as the miniballs. Its mass and the effect of
gravity usually negligible, a miniball released into the
bloodstream will continue to move with the current despite
collateral factors, such as the blood pressure and position
position of the body. A stenting miniball that enters the
circulation must do so during or following discharge.
[4079] While highly improbable, this could happen due to an airgun
malfunction, discharge that is faulty due to human error, or
failure of the magnetic stent-jacket, such as an interim migration
due to improper fixation, all of which can be observed with the
proper imaging equipment. The arresting, safe resituation to a
location outside the vessel, and if necessary, extraction entirely
outside the body of a miniball is accomplished with downstream
magnets. Those implanted incorporate permanent magnets and are
absorbable or permanent according to the application. While
impasse-jackets are specialized to trap and/or hold miniballs, any
more strongly magnetized downstream stent-jacket will trap a
miniball loose in the circulation and continue to hold the miniball
unless the strength of jacket magnetization were to drop beneath
that required to do so, which the use of neodymium lanthanoid
virtually eliminates.
[4080] Exceptionally, an absorbable radiation shield-jacket, used
to suspend seed miniballs in the lumen alongside the lesion or
stent-jacket used to shield ductus-intramurally implanted seed
miniballs only so long as necessary, will allow a miniball to be
extracted when necessary. Such jackets have an absorbable outer
radiation shield, as addressed above in the section entitled
Radiation Shield-jackets and Radiation Shielded Stent-jackets
Absorbable and Nonabsorbable, about an extraction grid, usually
made of a magnesium alloy formulated to be absorbed over a longer
period when not permanent. Extracorporeal interception, relocation,
and extraction is by means of an electromagnet.
[4081] A permanent impasse-jacket protects against miniball
embolization at any time and will suspend medication miniballs or
draw drug carrier nanoparticles from a ferrofluid administered at
any later date. Medication miniballs are absorbed, limiting the
risk of embolization to a more or less predictable interval, and
contain sufficient ferromagnetic content to allow prompt emergency
retrieval if necessary. Irradiating miniballs are likewise
preloaded with superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder. The utility of any external
magnet whether hand-held or through adaptation of the B.sub.0
magnet of a magnetic resonance machine, as addressed in section X2c
below entitled Stereotactic Arrest and Extraction of a
C/irculating, Dangerously Mispositioned, or Embolizing Miniball, is
critically dependent upon and directly proportional to the focus or
targeting ability of the magnetic field.
[4082] The means for achieving a tight focus are described, this
factor critical to establishing the clearance required to nearby
implants containing ferrous matter in order not to disrupt these.
The type field used for magnetic heat induction, which may likewise
make use of magnetic resonance machine magnets, is alternating, not
static. Powerful static fields can attract ferrous objects as to
pose a projectile hazard and alternating fields will induce heat in
unintended objects containing ferrous metal (see, for example,
Hartwig, V., Giovannetti, G., Vanello, N., Lombardi, M., Landini,
L., and Simi, S. 2009. "Biological Effects and Safety in Magnetic
Resonance Imaging: A Review," International Journal of
Environmental Research and Public Health 6(6):1778-1798; Schenck,
J. F. 2000. "Safety of Strong, Static Magnetic Fields," Journal of
Magnetic Resonance Imaging 12(1): 2-19).
[4083] Mere attentiveness precludes such mishaps. Once a miniball
with deep surface texture becomes infiltrated with tissue, it can
be left in place indefinitely. If for any reason this is not
wanted, then a sudden pulse from a powerful external electromagnet
is used to pull the miniball outside the ductus to a safe location
within or entirely out of the body. Sudden extraction by this means
should impose minimal trauma, which can be assured when an
impasse-jacket, as addressed above in the sections entitled Concept
of the Impasse-jacket and Miniball and Ferrofluid-borne
Particle-impassable Jackets, or Impasse-jackets, has been
prepositioned about the miniball at the time of introduction.
[4084] While necessitating minor surgery to preposition, an
impasse-jacket can spare the need for any other measures to
intercept, hold, and extract the miniball. Once trapped in the
jacket, unless radioactive, releasing a drug or drugs that would be
mistargeted, or a need for resonance imaging without burning the
site arises, the miniball need not be extracted. When the
extractive force is less than shocking to the surrounding tissue,
the grid of an impasse-jacket, because it frames about the
miniball, protects against the tearing of adjacent tissue. The
removal of a tissue integrated miniball or stay should never
require excision.
[4085] The third method for steering or drawing nano and
microtherapeuics deep within the body using an extracorporeal
magnetic field is addressed shortly above. Stopping a larger
miniball from continued travel is similar to drawing drug carrier
nanoparticles from the blood where obtaining a locoregionally
high-gradient magnetic field is an ongoing area of research for
targeting drug delivery (see, for example, Shapiro, B. 2009, Op
cit.; Polyak, B.and Friedman, G. 2009 Op cit.; Chen, H., Kaminski,
M. D., Pytel, P., Macdonald, L., and Rosengart, A. J. 2008, Op
cit.).
[4086] Barrel-assemblies for use in the vascular tree incorporate
recovery electromagnets and a run-ahead embolic filter that
significantly reduce the risk of a miniball entering the
bloodstream. Should it occur, a miniball released into the
circulation miniball is intercepted and relocated or recovered
before it can embolize. If it does so, then it can be promptly
removed. Magnetic stent-jackets incorporate multiple features to
resist gradual migration and sudden dislodgement and are
formulated, then encapsulated, to resist chemical breakdown and
preserve unit integrity.
[4087] X2a(1). Midprocedural Interception and Recovery of a
Miniball Entering the Circulation
[4088] Since, whether due to human error or malfunction, the
magnets in the muzzle-head may be unerergized or the filter
undeployed, measures must be provided to intercept and recover a
miniball released into the bloodstream, these precautions
notwithstanding. Precautionary measures against the risk of
embolization consist of prepositioning interception magnets
downstream. When the risk will persist postprocedurally,
impasse-jackets are implanted. Where possible, the preabsorption
life of these is keyed to the potential duration of the risk. Risk
pertinent midprocedurally is protected against with an external
electromagnet and any impasse-jacket or more powerfully magnetized
stent-jacket prepositioned downstream.
[4089] The spherical surface of the miniball and its relatively
small mass of ferromagnetic material, especially when not meant for
stenting, require the use of a powerful tractive or separator-type
electromagnet. Platelet blockade having been administered, an
extracorporeal tractive electromagnet with field concentrating and
directing subulate probe is prepositioned sufficiently downstream
from other implants to seize and hold any miniball that flows
past.
[4090] The miniball is held against the lumen wall, the muzzle-head
brought up alongside, and its recovery electromagnets used to
retrieve the miniball. Periodic imaging of the segment of the
ductus in the magnetic path also discloses a failure to
successfully implant that might otherwise go undetected. If this is
impossible, as when the lumen will not admit the muzzle-head, then
the miniball is prevented from circulating by retracting it into or
through the lumen wall. If through and the blood is infected, an
antibiotic is used. By definition, the miniball will be minute
relative to the ductus in which it was to have been implanted, so
that a breach will spontaneously close promptly if not
immediately.
[4091] If the wall is thick and reentry into the lumen implausible,
then the sterile and minute miniball is allowed to remain. If the
wall is thin, then the miniball is forcibly extracted into the
neighboring tissue where, if innocuous, it is allowed to remain. If
the end position poses a danger, then the miniball is forcibly
extracted entirely out of the body over the most direct and safe
path, as described in section X2c below entitled Stereotactic
Arrest and Extraction of a Circulating, Dangerously Positioned or
Embolizing Miniball. Provided a safe path is available, forcible
extraction from within the body is an option whether during
discharge or thereafter.
[4092] X2a(2). Postprocedural Recovery of a Miniball in the
Vascular Tree
[4093] Once placed, an impasse-jacket will stop a miniball from
continued travel through the bloodstream whether mid- or
postprocedurally. The impasse-jacket can be left in place and
should not significantly demagnetize over the life of the patient.
In the very young, the possibility of demagnetization over time may
be compensated for with stronger magnetization. The same does not
apply to stent-jackets, magnet-jackets, and patch-magnets, for
example, which act directly on tissue in such a way that excessive
traction can result in perforation or delamination, for
example.
[4094] Miniballs are too small to occlude the lumen at the level
targeted, and subjacent to adluminal tissue of the lumen wall while
drawn abluminally (radially outward away from the lumen) by the
magnetic stent-jacket, are not likely to enter the bloodstream;
however, were such to occur, the miniball would have to be stopped
before it became an embolism. The small miniball-to-lumen diameter
ratio means that miniballs are far upstream from an eventual point
of occlusion, affording a significant distance over which one or
more stopping-magnets can be prepositioned. Where the situation
warrants, one or more miniball impasse-jackets as addressed above
in the section entitled Miniball Impasse-jackets or Guards are
prepositioned downstream.
[4095] The asymptomatic release from the treatment stent of a
miniball is detected with the aid of a periodic radiograph. Removal
or extraction is a clinical judgment based upon the possible
consequences of inaction. If necessary, the miniball is removed by
means such as described below in section X2c entitled Stereotactic
Arrest and Extraction of a Circulating, Dangerously Mispositioned,
or Embolizing Miniball. As addressed above in the sections entitled
(The Intraductal Component of the Extraluminal Stent and the Means
for Its Insertion and Double-wedge Stent-jacket Rebound-directing
Linings), the risk of perforation as a deterrent can be avoided by
prepositioning the stent-jacket. Previous exposure of the ductus
nullifies any objection to the separate percutaneous access
required.
[4096] When the barrel-assembly is used to target a lesion for the
delivery of medication unrelated to stenting, however, separate
access is avoided. Whether by rebounding off a prepositioned
stent-jacket, some other midprocedural mishap, or the later
sustaining of a direct blow, entry into the circulation of one or
more miniballs must have countermeasures. Miniballs are inserted
beneath the adventitia at an acute antegrade angle to undercut the
inner layers of the lumen wall, additional retentive strength or
anchoring imparted when a textured surface is infiltrated by the
surrounding tissue. Mechanical retention can be increased through
the use of miniballs coated with a protein solder that is heated
just after implantation. In a magnetic stent-jacket, the pull of
the magnets additionally acts to retain the miniballs in
position.
[4097] Moreover, the stent-jacket is held in position by its
resilience, attraction of its magnets to the intraductal miniballs,
and end-ties. As addressed in the section above entitled Protective
Encapsulation of the Stent-jacket, the base-tube with magnets is
encapsulated for chemical isolation and to bind the elements of the
extraductal component of the stent into a unit that make the
migration or dropping away of the retentive magnets improbable.
These factors militate against the accidental release of miniballs
into the lumen even were the stent to take a direct blow.
[4098] Several methods exist to prevent miniball embolization,
especially significant in carotid stenting where emboli can pass to
the brain. Distal and proximal protective embolic filters, balloon
barriers, and the application of an external magnetic field or
focused ultrasonic beam are addressed above in section X1 entitled
Use of An External Electromagnet to Assist in Steering or in
Freeing the Muzzle-head, and the magnetic content of miniballs
allows such alternative methods of breakdown in addition to
conventional means of filtration and mechanical blockage. Only the
smallest minihalls fall within the size range of microemboli which
are irretrievable and believed to cause silent watershed or border
zone microinfarcts (see Momjian-Mayor, I. and Baron, J. C. 2005.
"The Pathophysiology of Watershed Infarction in Internal Carotid
Artery Disease: Review of Cerebral Perfusion Studies," Stroke
36(3):567-577).
[4099] Additionally, even when as small as an embolus resulting
from an atherothrombogenic plaque fracture, or as the spontaneous
result of an emboligenic disorder, or through release during a
transluminal procedure to effect blockage at a level which results
in a cerebral infarction, a miniball released into the vascular
tree will be singular or few in number and not likely to educe a
consequence associated with the release of a large number of
thromboemboli. Unless formulated to remain temporarily, a miniball
used to stent is not, however, resorbable or susceptible to
thrombolytic medication, so that its landing site will determine
whether it should be left undisturbed as innocuous, or must be
resituated or extracted as addressed above in sections 12 entitled
Concept of the Impasse-jacket and I15 entitled Miniball and
Ferrofluid-impassable Jackets, or Impasse-jackets.
[4100] Infarction tends to be proportional to the level of stenosis
regardless of cause, whether atherothrombogenic and local or
cardioembolic (see, for example, Polito, V., La Piana, R., Del
Pilar Cortes, M., and Tampieri, D. 2017. "Assessment of Clot Length
with Multiphase CT Angiography in Patients with Acute Ischemic
Stroke," Neuroradiology Journal 30(6):593-599; Seitz, R. J. and
Donnan, G. A. 2015. "Recovery Potential after Acute Stroke,"
Frontiers in Neurology 6:238; Thanvi, B. and Robinson, T. 2007.
"Complete Occlusion of Extracranial Internal Carotid Artery:
Clinical Features, Pathophysiology, Diagnosis and Management,"
Postgraduate Medical Journal 83(976):95-99; Lodder, J., Hupperts,
R., Boreas, A., and Kessels, F. 1996. "The Size of Territorial
Brain Infarction on CT Relates to the Degree of Internal Carotid
Artery Obstruction," Journal of Neurology 243(4):345-349; Olsen, T.
S., Skriver, E. B., and Herning, M. 1985. "Cause of Cerebral
Infarction in the Carotid Territory. Its Relation to the Size and
the Location of the Infarct and to the Underlying Vascular Lesion,"
Stroke 16(3):459-466). Furthermore, the stent is usually placed
following an angioplasty that removed or debulked the stricture, so
that only an embolus larger than a miniball could occlude the
lumen. Midprocedural growth in the potential obstruction by clot
adhesion to the miniball is suppressed medically.
[4101] Restenosis suppressive measures should perpetuate this
patency. The miniball is likely to be stopped at a level that if
lacking collateral circulation, still has a small extent of
dependency. Postprocedural administration of anticoagulant
medication need not continue past anchoring by tissue infiltration.
Where collateral circulation is lacking, an embolizing miniball is
either drawn into a safe location as described above, or is
extracted as described in section X2c below entitled Stereotactic
Arrest and Extraction of a Circulating, Dangerously Positioned, or
Embolizing Miniball. Stays should rarely if ever necessitate
retrieval by such means, even as the result of a direct blow.
[4102] X2b. Stereotactic Resituation of a Mispositioned
Miniball
[4103] In many if not most instances, a mispositioned miniball,
which will usually be a fraction of a millimeter in diameter, is
best left undisturbed. The ability to resituate a mispositioned
miniball with an external electromagnet depends upon the relation
between the resistance to penetration by the miniball of the tissue
and the strength of the magnetic field. A hand-held electromagnet
is adequate to extract a miniball through soft and tissue and
aponeuroses, for example. A magnetic resonance machine adapted as
described below will extract a miniball trapped behind the hardest
tissue. The magnet is pulsed at an apposite level of current to
incrementally draw the miniball into the target location. The same
method can be used to nudge a closely misplaced miniball into the
desired location.
[4104] The miniball can be drawn into the circulation with a second
magnet prepositioned to incept it, then the interception magnet
used to pulse the miniball into the surrounding tissue if not the
desired location. For emergency interception and extraction
midprocedurally using a preplaced impasse-jacket or an external
electromagnet, sufficient ferromagnetic material must be dispersed
throughout an absorbed, to include a drug-releasing miniball, so
that its magnetic susceptibility does not degrade with its
dissolution to the point where it is no longer extractable. For
arrest and extraction, the magnetically susceptible material,
ordinarily superparamagnetic magnetite or maghemite nanoparticles
or finely grained powder; or for heat induction, iron grains.
[4105] Uniform distribution also affords greater iron particulate
surface area for absorption and eliminates any need to extract a
relatively large core. A miniball in the brain is pulse-drawn into
a vessel that will allow it to be intercepted by a prepositioned
magnet once no longer intracranial, or if judged too risky, then
into a ventricle or the subarachnoid space. Extravasation attendant
upon the perforation of an intracranial vessel by a miniball less
than one millimeter in diameter is not comparable to that following
the rupture of an arteriovenous malformation or an aneurysm.
[4106] Any volume of blood released thereby should resorb in a day
(Kim, J. Y. and Bae, H. J. 2017. "Spontaneous Intracerebral
Hemorrhage: Management," Journal of Stroke 19(1):28-39; Maugeri,
R., Anderson, D. G., Graziano, F., Meccio, F., Visocchi, M., and
Iacopino, D. G. 2015. "Conservative vs. Surgical Management of
Post-traumatic Epidural Hematoma: A Case and Review of Literature,"
American Journal of Case Reports 16:811-817; Sahni, R. and
Weinberger, J. 2007. "Management of Intracerebral Hemorrhage,"
Vascular Health and Risk Management 3(5):701-709; Dabrowska, E.,
Jagodzi ski, Z., and Michalak, W. 1992. "Remarks on Conservative
Treatment of Cerebral Hematoma," (in Polish with English abstract
at Pubmed), Neurologia i Neurochirurgia Polska [Polish Neurology
and Neurosurgery] Supplement 1:276-282; Koziarski, A. 1991.
"Conservative Treatment of Post-traumatic Intracerebral Hematoma,"
(in Polish with English abstract at Pubmed), Neurologia i
Neurochirurgia Polska [Polish Neurology and Neurosurgery]
25(2):230-237; Bidzi ski, J., Koziarski, A., and Frankiewicz, E.
1989. "Conservative Treatment of Intracranial Hematomas and the
Dynamics of their Resorption," (in Polish with abstract in English
at Pubmed) Neurologia i Neurochirurgia Polska [Polish Neurology and
Neurosurgery] 23(1):27-34). Except in the brain, a suitably located
miniball not containing a metal or metal containing shell or
magnetized lanthanoid can be lithotripsied' in place. The brain
excepted, if the attempt to move the miniball to a more effective
or safe location fails, it can be extracted entirely outside of the
body as addressed in the following section entitled Stereotactic
Arrest and Extraction of a Circulating, Dangerously Positioned, or
Embolizing Miniball.
[4107] X2c. Stereotactic Arrest and Extraction of a Circulating,
Dangerously Mispositioned, or Embolizing Miniball
[4108] As addressed at numerous points throughout this
specification, an errant miniball is recoverable in any
circumstance. With sufficient field force, a magnet can draw a
miniball entirely outside the body. While the risk for significant
trauma with such small implants is slight, the path is
predetermined to minimize injury to intervening tissue. Rather than
entirely outside the body, the miniball, which is not harmful to
untargeted tissue, is extracted to an extraluminal but
intracorporeal location, preferably, just outside the ductus. The
action is intended to preempt any ability of the tissue to resist
extraction and may be thought of a the reverse or reciprocal of
ballistic implantation, which similarly seeks to effect infixion
with such suddenness that minimal disruption or trauma results.
Except in the brain, a suitably located miniball not containing a
metal shell or magnetized lanthanoid can be lithotripsied in place.
The brain excepted, if the attempt to move the miniball to a more
effective or safe location fails, it can be extracted entirely
outside of the body as addressed in section X2c entitled
Stereotactic Arrest and Extraction of a Circulating, Dangerously
Positioned, or Embolizing Miniball.
[4109] The fine probe, which concentrates the flux to avoid
nontargeted implants, consists of a soft iron core or armature
supported by strong bracing on a strong cart that allows an
extension of the core to be rolled into central axial relation with
the tunnel (bore, gantry) of a magnetic resonance machine. A
miniball that rebounds into the lumen of an artery is carried away
from the other miniballs reducing the difficulty in singling it out
for arrest and extraction. The miniball is resituated to a safe
location within, or if necessary as when the miniball is a high
dose-rate radiation seed, extracted entirely out of the body. To
control the end point, extraction is generally pulsed to retract
the miniball in increments determined by the resistance of the
tissue to penetration.
[4110] Only the outer or B.sub.0 magnet is used. The need to effect
extraction along a predeterimined path is only slightly greater in
the improbable event that a stay requires forcible extraction, as
addressed above in section 4g entitled Emergency Recovery of
Miniballs and Stays. The cart is then bolted or otherwise securely
fastened to anchors welded or otherwise securely fastened to the
machine. The core is stepped down in diameter at intervals by
division into two or more arms connected by airgapless gimbal or
hinge joints at right angles to each other. These joints as well as
the cart, can be motorized, the cart can move along rails, and the
process controlled from a distance. The terminal arm ends in a
narrow section that concentrates the lines of force so that these
can be focused by pointing in any forward direction.
[4111] Materials testing results for the perforation resistance of
human tissue to a miniball of given diameter when drawn by a
magnetic field obtained as indicated are wanting; however, that a
magnetic resonance machine is able to generate a field of
sufficient strength to extract a miniball through hard tissue much
less the integument, for example, should leave little doubt as to
the functionality of this approach for miniball resituation or
extraction. Analogous studies suggest approaches to the study of
penetration and perforation of different ductus walls other than
those set forth below in section XVII entitled Testing and Tests
(see, for example, Nolan, G., Hainsworth, S. V., and Rutty, G. N.
2018. "Forces Generated in Stabbing Attacks: An Evaluation of the
Utility of the Mild, Moderate and Severe Scale," International
Journal of Legal Medicine 132(1):229-236; MacManus, D. B.,
Gilchrist, M. D., and Murphy, J. G. 2017. "An Empirical Measure of
Nonlinear Strain for Soft Tissue Indentation," Royal Society of
England Open Science 4(11):170894; Beekmans, S. V., Emanuel, K. S.,
Smit, T. H., and Iannuzzi, D. 2017. "Minimally Invasive
Micro-indentation: Mapping Tissue Mechanics at the Tip of an 18G
Needle," Scientific Reports 7(1):11364; Limbert, G. 2017.
"Mathematical and Computational Modelling of Skin Biophysics: A
Review," Proceedings of the Royal Society of London, Series A.
Mathematical, Physical, and Engineering Sciences
473(2203):20170257; Griffin, M., Premakumar, Y., Seifalian, A.,
Butler, P. E., and Szarko, M. 2016. "Biomechanical Characterization
of Human Soft Tissues Using Indentation and Tensile Testing,"
Journal of Visualized Experiments (118); Li, W. and Luo, X. Y.
2016. "An Invariant-based Damage Model for Human and Animal Skins,"
Annals of Biomedical Engineering 44(10):3109-3122; Ni Annaidh, A.,
Cassidy, M., Curtis, M., Destrade, M., and Gilchrist, M. D. 2015.
"Toward a Predictive Assessment of Stab-penetration Forces,"
American Journal of Forensic Medicine and Pathology 36(3):162-166;
Budday, S., Nay, R., de Rooij, R., Steinmann, P., Wyrobek, T.,
Ovaert, T. C., and Kuhl, E. 2015. "Mechanical Properties of Gray
and White Matter Brain Tissue by Indentation," Journal of
Mechanical Behavior of Biomedical Materials 46:318-330; Weisbecker,
H., Unterberger, M. J., and Holzapfel, G. A. 2015. "Constitutive
Modelling of Arteries Considering Fibre Recruitment and
Three-dimensional Fibre Distribution," Journal of the Royal Society
of England Interface 12(105). pii: 20150111; Ni Annaidh, A. N.,
Cassidy, M., Curtis, M., Destrade, M., and Gilchrist, M. D. 2013.
"A Combined Experimental and Numerical Study of Stab-penetration
Forces," Forensic Science International 233(1-3):7-13; Parmar, K.,
Hainsworth, S. V., and Rutty, G. N. 2012. "Quantification of Forces
Required for Stabbing with Screwdrivers and Other Blunter
Instruments," International Journal of Legal Medicine 126(1):43-53;
van Dommelen, J. A., van der Sande, T. P., Hrapko, M., and Peters,
G. W. 2010. "Mechanical Properties of Brain Tissue by Indentation:
Interregional Variation," Journal of the Mechanical Behavior of
Biomedical Materials 3(2):158-166; Ankersen, J., Birkbeck, A. E.,
Thomson, R. D., and Vanezis, P. 1999. "Puncture Resistance and
Tensile Strength of Skin Simulants," Proceeding of the Institution
of Mechanical Engineers. Part H, Journal of Engineering in Medicine
213(6):493-501; Jussila, J., Leppaniemi, A., Paronen, M., and
Kulomaki, E. 2005. "Ballistic Skin Simulant," Forensic Science
International 150(1):63-71).
[4112] Medication and radiation seed miniballs and stays are used
without a stent-jacket and are not blocked by a jacket from outward
(axifugal, abluminal) recovery. When avoidable, direct percutaneous
(acrotic, integumentary) incision is not preferred as risking
luminal entry. Outward removal of stent miniballs and stays must
allow for the interposition of the jacket. Miniballs are drawn
through the outer tunic or tunics and into the moisture
barrier-coated viscoelastic polyurethane foam lining of the
base-tube with the aid of a powerful external (extracorporeal)
electromagnet. Recovery without breaching the intima means that
there is less difficulty and risk than there is in the recovery of
an endoluminal stent. Stays are not recoverable thus; however,
fixed in place with a coating of cement and integrated into the
surrounding tissue, are not susceptible to migration, and should
not require removal, which is surgical.
[4113] X2d. Downstream Disintegration of a Circulating Miniball
[4114] The preprocedural positioning of a powerful electromagnet
along the vascular tree downstream from the treatment site allows
any miniball without toxic, radioactive, or nonabsorbable content
that incorporates ferrous content and means for its disintegration
that enters the circulation to be disintegrated on demand without
awareness as to its exact location. For this purpose, all miniballs
already incorporate sufficient magnetically susceptible, typically
ferrous, content to permit arrest and extraction should conditions
necessitate. Adequate susceptibility to magnetic traction is
satisfied with the incorporation of sufficient superparamagnetic
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder.
[4115] With these, the greatest surface area is that optimal and
yields the quickest absorption time. Induction is more efficient
with larger grains of iron, which may be obtained by sintering
sufficient superparamagnetic magnetite or maghemite nanoparticles
or finely grained powder but is more often solid. The iron content
is absorbable over time, extractable if microembolizing as to cause
discomfort, and rarely if ever sufficient in quantity to reach the
toxic level at about 350 micrograms per deciliter serum iron (The
Merck Manual of Diagnosis and Therapy, 18th edition, pages
2667-2668). Means incorporated into miniballs to allow their
destruction by heat induction are addressed above in the section
entitled Noninvasive dissolution on demand of absorbable
stent-jackets, base-tubes, radiation shields, and miniballs.
[4116] X3. Perforations Along the Gastrointestinal Tract
[4117] Perforation along the digestive or gastrointestinal tract
can occur during implantation discharge as accidental but not as
the result of an intentional extraction, which owing to the gauge
of the ductus, can always be accomplished endoluminally. Compared
to other iatrogenic and to pathological perforations, those caused
by miniballs are tiny, close spontaneously, and do not allow flora
to be released in large numbers through spillage. Pathogens in
lower numbers will, however, be carried forward into the
surrounding cavity on septic debris forced ahead of and adherent to
the relatively tiny miniball when it exits. Gastrointestinal
perforation treated of in the literature involves much larger
wounds and the discharge of relatively large volumes of septic
debris. Reference to the literature below pertain only to such
breaches when severe, such as the result of resecting a malignancy
or typhoid perforation.
[4118] Provided the subject is immunocompetent, infection from the
tiny breach should eventuate slowly with a severity responsive to
antibiotics (Min, B. S. 2016. "Intestinal Perforation: A Surgeon's
Nightmare Enlightened by Scientific Research," Annals of
Coloproctology 32(6):205; Shin, R., Lee, S. M., Sohn, B., Lee, D.
W., Song, I., and 6 others 2016. "Predictors of Morbidity and
Mortality after Surgery for Intestinal Perforation," Annals of
Coloproctology 32(6):221-227; Medina, E. 2010. "Murine Model of
Polymicrobial Septic Peritonitis Using Cecal Ligation and Puncture
(CLP)," Methods in Molecular Biology 602:411-415; Agarwal, N.,
Saha, S., Srivastava, A., Chumber, S., Dhar, A., and Garg, S. 2007.
"Peritonitis: 10 Years' Experience in a Single Surgical Unit,"
Tropical Gastroenterology 28(3):117-120; Wong, P. F., Gilliam, A.
D., Kumar, S., Shenfine, J., O'Dair, G. N., and Leaper, D. J. 2005.
"Antibiotic Regimens for Secondary Peritonitis of Gastrointestinal
Origin in Adults," Cochrane Database of Systematic Reviews
(2):CD004539), and respond to antibiotic therapy without the need
for surgical intervention.
[4119] XI. Hypdxia and Ischemia-Averting Elements
[4120] The dimensional restrictions for adequate therapeutic
maneuvering are generally severe even when allowances for oxygen to
pass need not be considered, as in a ureter, for example, and is
the incentive for Barrel-assemblies which incorporate hypoxia
countering features and those that achieve ablation or angioplasty
capability as bipartite where the outer or ensheating projection
catheter is interim withdrawable as necessary.
[4121] The features incorporated into a barrel-assembly to minimize
the cutoff of oxygen (hypoxia, mionexia, anoxia) in the bronchi or
in blood vessels through angiemphraxis vary depending upon the
maximum outer diameter permissible, the functional capabilities
that must be accommodated within this diameter, the degree of
flexibility essential to track the type ductus, and the type of
barrel-assembly. Even with the features addressed below, the
muzzle-head should never be so broad as to prevent blood from
flowing past it on the systoles.
[4122] For example, provided unobstructed side-ports are present,
the unoccupied through-bore can be used to allow blood to pass
through a combination-form barrel-assembly or radial projection
catheter. Blood-tunnels allow some flow through the
barrel-catheter, but other components unaffected, reduce
flexibility when inclined longitudinally to allow some
flow-through. If deep enough, blood-grooves on the muzzle-head can
allow sufficient blood to pass, or to pass when a combination-form
radial projection catheter is withdrawn.
[4123] When angioplasty in a coronary artery is to be followed by
stenting discharge to place the implants, the barrel-assembly is
not withdrawn following angioplasty but inserted into the airgun to
initiate stenting. Then, even though the apparatus has been devised
to minimize procedural time and present a minimal cross-sectional
area, unless active means are incorporated for minimizing hypoxia,
the risk of an infarction is unacceptable. While preferably
avoided, the use of newer bypass machines, as mentioned above,
should not result in the neurocognitive deficits observed in the
past.
[4124] XI1. Blood-Grooves
[4125] Blood-grooves pertain to the radial discharge muzzle-heads
addressed above in the section entitled Blood-grooves on
muzzle-heads for use in blood vessels.
[4126] XI2. Blood-Tunnels
[4127] Blood-tunnels pertain to barrel-catheters and are addressed
above in the section of like title beneath the heading Radial
discharge barrel-assembly elements. Blood-tunnels also serve as
tube polymer-nonintrinsic barrel-catheter flexibility (bendability,
trackability) altering elements. The alternative use of lining or
casing lengths of metal tubing concentric with the barrel-catheter
is considered obvious.
[4128] XI3. Flow-Through Bore in Combination-Form Barrel-Assemblies
and Combination-Form Radial Projection Catheters Used in Blood
Vessels
[4129] While unoccupied and disposed either antegrade or retrograde
to the flow of blood, the central channel of a combination-form
barrel-assembly or a combination-form radial projection catheter
can be used to allow blood to flow between a side-port or ports and
the nose or front end. When antegrade, blood flows into the
side-ports and out the nose-hole, whereas when retrograde, flow is
into the nose-hole and out the side-ports. This is addressed above
in the sections entitled Side-ports, Flow-through Barrel-assembly
for Use in Blood Vessels, Through-bore, or Combination-form, Radial
Projection Catheters, and Through-bore, or Combination-form,
Barrel-assemblies: Barrel-assemblies which Accommodate or
Incorporate Means for Ablation, Thrombectomy, Atherectomy,
Atherotomy, and/or Endoscopy. Such use can be aided by push-arm
tool-inserts used to provide greater clearance between the outside
of the catheter and the lumen wall.
[4130] XI4. Push-Arm Radial Projection Unit Tool-Inserts
[4131] Radial projection units are incorporated into radial
discharge muzzle-heads, addressed above in the section entitled
Muzzle-head radial projection units, and combination-form radial
projection catheters. While blank-faced push-arm tool-inserts are
specifically intended to allow the muzzle-head to be pushed in the
opposite direction allowing blood to pass, almost any tool-insert
without sharp projections on the pushing face can be used to
accomplish such action. In a combination-form barrel-assembly or
radial projection catheter with distal side-ports to allow blood to
flow through the central channel or bore, the push-arms not only
provide some peripheral clearance but give better access of the
blood to the side-ports.
[4132] XII. Service-Catheters
[4133] A service-catheter is led (snaked, fed) down through a
barrel-tube to access the lumen or lumen wall at the exit-hole or
exit-port while intracorporeal, that is, midprocedurally, without
the need for withdrawal and reentry. In so doing, the barrel-tube
is used as a guide catheter. A service-catheter can be used, for
example, to conduct a fluid for release at the exit-hole; if
provided with an injection needle at the distal end, then to serve
as a hyppotube for injecting the lumen wall; to convey electrodes
for nonthermal irreversible electroporation ablation addressed just
below, or electrochemotherapy (Hampton, T. 2011. "Electric Pulses
Help with Chemotherapy, May Open New Paths for Other Agents,"
Journal of the American Medical Association 305(6):549-551; Moller,
M. G., Salwa, S., Soden, D. M., and O'Sullivan, G. C. 2009.
"Electrochemotherapy as an Adjunct or Alternative to Other
Treatments for Unresectable or In-transit Melanoma," Expert Reviews
of Anticancer Therapy 9 (11): 1611-1630; Sersa, G., Miklavcic, D.,
Cemazar, M., Rudolf, Z., Pucihar, G., and Snoj, M. 2008.
"Electrochemotherapy in Treatment of Tumours," European Journal of
Surgical Oncology 34(2): 232-240), or any small cabled device, such
as a laser or scope. The proximity of the recovery electromagnets
negates the need for service-catheters with a magnet tip.
[4134] Service-catheters are applicable to simple pipe-type
barrel-assemblies with a luminal diameter that will accommodate a
laser or scope fed through a proximal barrel-catheter side-port or
through the proximal end of the barrel-assembly when disconnected
from the airgun. Miniaturization allows the insertion within a
luminal wall to ablate diseased tissue therein, such as a tumor, of
a nonthermal electric pulse conducting probe tool-insert (see, for
example, Arena, C., Sano, M., Rossmeisl, J., Caldwell, J., Garcia,
P., Rylander, M., and Davalos, R. 2011. "High-Frequency
Irreversible Electroporation (H-fire) for Non-thermal Ablation
without Muscle Contraction," BioMedical Engineering OnLine
10(102):1-20; Neal, R. E. 2nd, Singh, R., Hatcher, H. C., Kock, N.
D., Torti, S. V., and Davalos, R. V. 2010. "Treatment of Breast
Cancer through the Application of Irreversible Electroporation
Using a Novel Minimally Invasive Single Needle Electrode," Breast
Cancer Research and Treatment 123(1):295-301; Al-Sakere, B., Andre,
F., Bernat, C., Connault, E., Opolon, P., Davalos, R. V., Rubinsky,
B., and Mir, L. M. 2007. "Tumor Ablation with Irreversible
Electroporation," Public Library of Science One 2(11):e1135;
Davalos, R. V., Mir, I. L., and Rubinsky, B. 2005. "Tissue Ablation
with Irreversible Electroporation," Annals of Biomedical
Engineering 33(2):223-231).
[4135] XIII. Service-Catheters, Service-Channels, and Use of the
Barrel-Assembly as a Guide-Catheter
[4136] A barrel-tube that is not needed for discharge can serve as
the service-catheter itself. For brush cytological purposes,
however, a service-catheter allows obtaining a sufficient tissue
sample for brush cytology without the need to maintain vacuum force
to retrieve the sample. The sample need be withdrawn no more than
past the distal end of the service-catheter, whereupon the catheter
is removed, and the sample blown onto the test medium. A
barrel-tube that will be needed for discharge is not fouled when
lined with a service-catheter. Service-catheters can serve as
conduits for pumping through fluid therapeutic substances into the
lumen, or, with a prefilled hypoendothelial or hypointimal
injection needle (hypotube) at the distal end, into the lumen wall.
The latter can be actuated by a manual plunger piston as in a
hypodermic syringe or powered in any of a number of ways.
[4137] More specifically, in feed-forward use, a service-catheter
can be used for drying, wetting, chilling, or heating (by
connection to a cold air gun, for example), to ablate, spray a
powder, liquid, or gas against the surface of the lumen, or inject
a fluid substance through the endothelium. In feed-back use,
aspirated materials can be tissue or any agent applied through feed
forward use. In use as a guide-catheter, a multiple barrel-tube
barrel-assembly can be rotated endoluminally with the turret-motor
to apply these processes in any desired sequence at a single tissue
target or as many targets as there are barrel-tubes. When connected
to an aspiration pump or bulb or syringe pipetted, a
service-catheter with a scalloped front edge can be used to shave,
scrape, or brush the lumen surface to obtain tissue samples.
[4138] Otherwise unused barrel-tubes or service-catheters can be
used in coordination with perforated radial projection unit
tool-inserts so that a fluid delivered through either can be drawn
toward and aspirated away by the other. Using tool-inserts in
longitudinally and/or circumrerentially separated radial projection
units and service-catheters to deliver and/or aspirate a fluid
allows the direction and path or areal path of flow over the lumen
wall to be controlled. When the tool-insert aspirates itself, the
controlled flow of fluid over the lumen wall terminates at the
treatment site. Piped radial projection units have a rear pipeline
or communicating conduit that allows the forward throughput of
chilling gas, for example, and reverse throughput or aspiration of
detritus or excess medication, cement, swelling or sclerosing
agent, for example.
[4139] These are addressed below in the sections entitled Piped
radial projection units and radial projection unit tool-inserts.
When the tool-insert, such as a side-cutter (side-cutting shaver),
is not piped and used to aspirate and is positioned between the
fluid inlet, such as a service-catheter, for example, and an outlet
such as a piped projection unit located on the opposite side of the
treatment site, for example, the flow between the two outer
components can be made to move over the intervening treatment site.
Lavage or the deposition of medication can be accomplished in a
similar manner, using either the barrel-tubes or perforated radial
projection unit tool-inserts to deliver and the other to draw off
the fluid, which can be heated or chilled. Perforated tool-inserts
can be used to deliver heated or chilled gas. When the fluid would
foul the barrel-tubes, a service-catheter is inserted down to the
exit port.
[4140] With a combination-form barrel-assembly, the fluid can be
delivered or drawn off through a tube passed down the central canal
to the nose, and use of a dual lumen tube frees the barrel-tubes
and tool-inserts for other functions. Tight controllability over an
area of the lumen wall can be attained in the application of
medication, change in temperature, or both in coordination.
Longitudinally separated temperature changing devices, whether
barrel-tubes, blank radial projection unit tool-inserts, or
electrical winding-heated heat-windows, can be used to emit and
take up a fluid and/or to establish a change from a higher to a
lower temperature at an intervening treatment site which may serve
thermal or cryogenic ablation or angioplasty in lieu of a
heat-window and cooling catheter, or the work of an intervening
radial projection tool.
[4141] Since radial projection units can encircle the muzzle-head,
the linear or areal extent of the lumen wall over which a
temperature gradient with or without medication can apply whether
past an intervening working tool-insert is unrestricted. Whereas
heat-windows can be used only to heat and require to be controlled
from a barrel-assembly-onboard ablation and angioplasty control
panel, radial projection units are more capable, the control of
medication, temperature, or both, for example, readily controlled
by heating or chilling the source cylinder connected to the
delivering side- or end-socket. The insulation value of the
polymeric barrel-catheter isolates the temperature change from the
lumen wall until emitted; however, the source must be temperature
compensated for the loss in cold or heat moving toward the exit
points.
[4142] The rate of heat loss moving forward down the barrel-tube is
increased if metal centering devices are used as these act as heat
sinks. Since the barrel-assembly is limited in rotation by means of
the turret-motor, that is, in working arc (qv.), a muzzle-head with
muzzle-ports in close circumferential relation can be used. The
working arc is rotated by rotating the barrel-assembly. When not
needed for discharge, any barrel-tube can itself be used as, rather
than used to conduit, a service-catheter. A side-socket (qv.) that
allows service-catheters to be inserted into and withdrawn from the
barrel-tubes without disconnection from the airgun allows
medication and/or an adhesive to be applied to the lumen surface or
subendothelially through a service-catheter such that the implant
discharged will pass through the same point; barrel-tube
lining.
[4143] XII2. Muzzle-Head Access Through a Service-Channel Without
the Aid of and by Means of Inserting a Service-Catheter
[4144] A service-channel is a barrel-tube or central canal used
itself or as a guide-catheter for a narrower service-catheter to
allow distal access for the delivery or aspiration of a fluid
substance. Service-catheters are essential as linings to prevent
fouling a barrel-tube that is to be used for discharge, and any
number and type may be used in succession in any one or a plurality
of barrel-tubes. A spare or extra barrel-tube and muzzle-port as
already contained within the barrel-assembly allow access to the
muzzle-head for the delivery of fluid substances, generally, with a
simple pipe, medication and with a radial discharge
barrel-assembly, medication or a lubricant.
[4145] A liquid is delivered through a catheter, or
service-catheter, to a syringe connected at the proximal end. The
use of a service-channel requires that the barrel-assembly be
disconnected from the airgun or that a proximal side entry portal
or socket be provided. Disconnection allows the same barrel-tube to
be used for discharge. Use of the central canal as a
service-channel in an edge-discharge barrel-assembly to be used in
the circulatory system is discounted as risking the clogging of the
air pressure equalization holes essential to avoid allows the
delivery of medication, for example, into the lumen, A side
barrel-tube entry socket is analogous to an ostomy where the
proximal end of the barrel-tube is diverted out the side of the
barrel-catheter where a syringe, bulb, pump, or any other delivery
or retrieval mechanism can be inserted as necessary.
[4146] A switch to allow changing connection of the
service-catheter from the airgun chamber to the side entry socket
without disconnecting the barrel-assembly from the airgun is
considered nonessential. In an ablation or ablation and
angioplasty-capable barrel-assembly, the barrel-tube side entry
socket can be incorporated into the electrical side-socket is
present. A ramrod or testing rod (addressed below) with outer
diameter just smaller than the internal diameter of this
muzzle-head service-channel, whether the central canal or a spare
barrel-tube, allows the substance to be delivered to the
muzzle-head by pushing the rod behind the substance down the
barrel. To minimize the loss of material by spreading along the
inner wall of the barrel, the ramrod is preferably made of a
fluoropolymer such as polytetrafluoroethylene.
[4147] Since any barrel-tube and muzzle-port can be used for
discharge, when a barrel-tube is to be reserved for such use, a
barrel-assembly including one more barrel-tubes than needed for
discharge is used. That is, barrel-assemblies are not made to
include a barrel-tube in excess of those that can be used for
discharge. Selecting a barrel-assembly with one more barrel-tubes
than is needed for discharge is then preferable to the use of a
barrel-tube used for discharge, because unless an additional
cleaning step is undertaken, the deposition of a film along the
walls and its accumulation along the bottom of the barrel-tube will
affect exit velocity and carry some of the deposited material into
the intratissue or wound trajectory.
[4148] Thus, when the number of barrel-tubes needed for discharge
and diameter of the implants necessitate a barrel-assembly that
with an extra barrel-tube would bring the barrel-assembly to too
large a diameter, one or more of the discharge barrel-tubes is used
and any problematic film coating left along the inside of the
discharge barrel-tube or tubes is wiped down with a second ramrod
having an absorbent felt or cotton covering. The use of a
service-channel to accomplish the intraductal injection or infusion
of medication into the lumen, or with the aid of a service-catheter
used as an injection-tube passed down a service-channel as
described above in the sections entitled Turret-motor Operational
Modes and Miniballs Coated with a Heat-activated (-melted,
-denatured) Tissue Adhesive-hardener or Binder-fixative, into the
ductus wall is considered obvious.
[4149] Outside the circulatory system, where service-channel
injectant or medicinal ejecta would not be immediately swept
downstream, a ductus wall swelling agent as addressed under the
section below entitled Muzzle-head Access through a Service-channel
Without the Aid of and by Means of Inserting a Service-Catheter can
be released. Such include, for example, acetone, of which the use
is not permissible in the airway, within proximity of the eyes, or
in the bloodsteam, or CO2 as drying agents; and CO2 or a cold air
gun for delivering cold. The use of a service-channel or channels
as guide-catheters or sleeves through which to advance a catheter
or catheters into the lumen or against the lumen wall for the
purpose of removing debris by connection to an aspirator pump is
addressed below in the section entitled Use of the Barrel-assembly
as an Aspirator or Transluminal Extraction Catheter for the Removal
of Soft Plaque or Mispositioned Miniballs.
[4150] The use of a service-channel to obtain biopsy samples, to
include those obtained by brush cytology (see, for example, Boberg,
K. M., Jebsen, P., Clausen, O. P., Foss, A., Aabakken, L., and
Schrumpf, E. 2006. "Diagnostic Benefit of Biliary Brush Cytology in
Cholangiocarcinoma in Primary Sclerosing Cholangitis," Journal of
Hepatology 45(4):568-574) accomplished with the side-brushes is
addressed below in the section entitled Use of the Barrel-assembly
as an Aspirator or Transluminal Extraction Catheter to Retrieve
Biopsy Samples. Whereas the retrieval of tissue samples obtained by
shaving or brush-type radial projection unit side-sweeper
tool-inserts necessitate withdrawal of the barrel-assembly, samples
obtained by aspiration do not. Absent an airgun, any
barrel-assembly can be used purely as a single or multiple channel
guide-catheter for the taking of tissue samples and/or the
application of medication along the internal surface of the
lumen.
[4151] While having been positioned endoluminally for another
primary purpose, larger barrel-tubes, to include simple pipes, can
be used secondarily as guiding catheters for a bioptome (see, for
example, Terasaki, K., Wittich, G. R., Lycke, G., Walter, R.,
Nowels, K., Swanson, D., and Lucas, D. 1991. "Percutaneous
Transluminal Biopsy of Biliary Strictures with a Bioptome,"
American Journal of Roentgenology 156(1):77-78) without the need to
withdraw the barrel-assembly, which can accordingly remain
prepositioned along the lumen to initiate discharge when the
laboratory results can be obtained quickly. Radial projection unit
side-sweeper type tool-inserts having projections that are
configured as mushroom shaped anchors, or downwardly directed
hollow domes to function much as an atherectomy catheter, such as
those shown in FIGS. 51a and 51b, allow the retrieval of more
material for analysis than those having projections of bristled
conformation.
[4152] XII3. Cyanoacrylate Cement Injection Service-Catheter
[4153] However mixed and low in viscosity, cyanoacrylate cement
must not be allowed to coat the interior of the barrel-tubes
through which miniballs are discharged. When the use of
cyanoacrylate is desired, consideration should be given first to
the use of stays. It is possible, however, to pass a
service-catheter (microcatheter) down an unused barrel-tube serving
as service-channel and inject cyanoacrylate cement after the
miniballs have been implanted. Such use is unintended and
discouraged in the vascular tree wherein it must never be attempted
without a trap-filter of sufficient capacity to prevent an
embolism. To better comply with the motility intrinisic in the
ductus, the cyanoacrylate cement should contain plasticizer,
several having been specified in the section above entitled
Miniballs Coated with a Heat-activated (-melted, -denatured) Tissue
Adhesive-hardener or Binder-fixative, for better stability, the
cyanoacrylate should be injected midway between the implanted
miniballs, and for viewability, the cyanoacrylate must contain
radiographic contrast.
[4154] To prevent the introduction of any cement into the
bloodstream as well as impart greater radiolucency, a proportion of
the mix must consist of superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder, recovery by the recovery
electromagnets distal to the muzzle-ports trapping any cement that
may escape. Eliminating the need to attach a separate hypodermic
needle, the tip of the microcatheter is itself beveled, the bevel
standard, short, or true short depending upon its wall thickness
and strength. When discharge is under machine control so that
positioning the microcatheter between the miniballs exceeds manual
capability, the positional control system is used to place the tip
of the microcatheter; however, the operator must manually inject
the cement.
[4155] The microcatheter must be fed the adhesive from a metering
pump and have a detent to limit the extension of the distal point
past the muzzle-port. When the microcatheter is used in an artery,
the cyanoacrylate adhesive is prevented from escaping downstream as
an embolism by mixing it with a small proportion of
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder. The relation between the initial setting time and
retention within a drop of cement of ferromagnetic particles so
that magnetic attraction can be used to recover the entire drop
rather than merely to extract the particles is addressed above in
the section entitled Arcuate stent-stays (stays, stent-ribs, ribs)
or Stays for use with stent-jackets.
[4156] The greater susceptibility to entry into the bloodstream of
endoluminal access through the intima as opposed to extraluminal
access through the adventitia with stays is counterbalanced by the
greater ease with which the transluminal apparatus allows
retrieval. A powerful hand-held permanent magnet or tractive
electromagnet can be used to prevent an adhesive containing
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder from passing downstream. The magnet is prepositioned
extracorporeally to intercept any ferrous material that might pass
until the recovery electromagnets in the muzzle-head are brought up
to retrieve the drop.
[4157] In so doing, the current to the extracorporeal magnet is
reduced as that of the recovery electromagnets in the muzzle-head
are increased, causing the drop to instantly trap itself within a
recovery electromagnet antechamber behind a recovery magnet hinged
door. Void of ferromagnetic material, pure medication miniballs and
any cement used the more securely to fix these in position are not
susceptible to inadvertent extraction once implanted through the
use nearby of an electromagnet to recover a lost or extract a
misplaced stay or miniball; however, the same lack of magnetic
attractability could free these elements to embolize.
[4158] Accordingly, loss downstream of nonferrous elements such as
pure medication miniballs or cement is prevented by incorporating
into these sufficient sterile superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder to overcome their
mass under the propulsive force of the bloodstream and thus allow
these to be trapped. Insoluble and lower in specific gravity than
blood serum, cyanoacrylate cement in blood coheres and floats. With
the pulse tending to drive the self-coherent drop forward and
buoyancy tending to drive it upward, the drop rises to the top of
the artery where, soft but intact, the drop will tend to become
stuck along the intima-lined ceiling for mechanical rather than
chemical reasons.
[4159] Instantly beginning to polymerize in the aqueous environment
of the blood, and thus trapping any particles of a ferrous metal
such as superparamagnetic magnetite or maghemite nanoparticles or
finely grained powder within it, the engagement of portions at the
boundary of the drop of cyanoacrylate that have become lodged
against the upper intima in the direction of current flow allows
the electromagnets to retrieve the drop easily against the current.
Even when the drop sets (polymerizes) in the form of a film having
an outer edge that is larger than the recovery electromagnet
antechamber doors, the ability of the adhesive to set to any
firmness before the magnets can retrieve them is lacking. At the
same time, the adhesive must have set to the extent that the iron
particles will remain trapped within the drop rather than be
attracted to the magnets leaving the drop to escape.
[4160] Since the cyanoacrylate contains contrast, the operator will
be aware of such a release or leak. When intraparietal bonding and
hardening are necessary, as when the wall to be implanted contains
a separation, a second occurrence of such a leak should prompt the
operator to end microcatheter injection in favor of dependence upon
solder. The maximum safe capacity of the antechambers for miniballs
of a given diameter can be stated accurately. However,
semisolidified drops of cyanoacrylate are irregular and varied in
conformation, and depending upon how one retrieved previously
happened to settle within the antechamber, can interfere with
antechamber door closure. The probability of door interference
rises the longer the drop is in the antechamber and is able to gain
hardness.
[4161] XII4. Service-Channel Adhesive Delivery Line
[4162] The injection of sclerosants using a flexible endoscope to
treat variceal hemorrhages has been practiced for well over half a
century. In order to adapt the technique for use with a
barrel-assembly to introduce cyanoacrylate cement about the
implanted miniballs as a tissue adhesive-hardener, the gauge of the
service-catheter used as an injection catheter must be fine enough
to pass down a barrel-tube and round the curve toward its distal
terminus in the approach to the muzzle-port. To enhance visibility
and retard premature setting, the adhesive is mixed with
radiographic contrast such as Lipiodol.TM..
[4163] XII5. Cooling Catheters (Temperature-Changing
Service-Catheters)
[4164] Cooling or temperature-changing catheters can be used either
to heat or cool the tissue under treatment or parts of the
apparatus. There are several types, some for attachment to stay
insertion tools and having holes on the sides and/or the distal
end. Some are distally close-ended with side-holes for snaking down
the central canal or a barrel-tube in order to cool down the
turret-motor and/or recovery electromagnet windings. Anticlotting
agents administered notwithstanding, following the use of heat for
thermal ablation or angioplasty, active cooling allows the
thrombogenic range of temperatures that stand between angioplastic
and room temperatures to be passed through more quickly. Other
cooling catheters for use in ductus other than blood vessels are
open-ended at the distal tip for emitting a chilling gas against
the lumen wall.
[4165] Cooling or temperature-changing service catheters fall into
two categories, depending upon whether a chilled gas or liquid is
made to flow through the catheter to direct the cold or heat for
therapeutic chilling or heating of the lumen wall or an enclosed
chamber at the distal end contains a refrigerant gel or liquid that
can retain cold or heat. The use of piped gas or liquid for
controlling temperature is substantially limited to the use of
muzzle-head and piped radial projection unit temperature-changing
`heat`-windows and when the temperature must be controllably
adjusted midprocedurally. Gels are available that retain either
heat or cold, so that withdrawal and insertion in a hot or cold
bath, for example, will allow the temperature to be quickly changed
for reentry into the barrel-assembly without the addition of water,
allowing permanent encasement of the gel within a chamber at the
distal closed off end of the cooling catheter.
[4166] These are generally cellulose or crosslinked sodium polymer
based. Companies specialized in the use of such materials include
Cold Ice, Incorporated, Oakland, Calif. and Zero-Pak Products,
Richmond, British Columbia. Because the proximal end-plate of the
barrel-assembly is engaged in the airgun chamber during discharge,
the application of cold to assist in stabilizing tissue during
discharge, for example, requires that the entry socket (receptacle,
union, coupling) into the barrel-assembly be of the side- rather
than the end-mounted type. A cooling (or heating) catheter of
capillary gauge, or cooling capillary catheter, is passed down a
spare barrel-tube (service-channel) or the narrower central canal
of a center-discharge barrel-assembly. When unoccupied by an
atherectomy cable, the central canal of a center-discharge
barrel-assembly will accommodate a cooling (or heating) catheter of
larger diameter, which can be a permanent part of a barrel-assembly
equipped with a nose-window.
[4167] Alternatively, to allow the use of different devices, the
central canal is left available so that a cooling catheter must be
inserted through the end or side-socket. A similarly temporary
nose-window must be inserted into the distal opening of the central
canal at the same time. Temperature changing gas delivery catheters
are also distinguished as capped (closed off, close-ended) or
capless (open, open-ended). To prevent gas embolism, those for use
in the bloodstream when the distal end is not blocked off from the
bloodstream by engagement in the cooling catheter insertion channel
of the ejection head are capped or if capless (open-ended), must be
direct the cold air from a vortex cold air gun or liquified gas
cartridge or hot air from the other outlet of the cold air gun
against toward the backside of a nose-window (qv.), or nose
heat-window.
[4168] XI16. Preparation of Service-Catheters for Use as
Transbarrel-Assembly Hypotubes
[4169] Protection against thrombosis using the means described
herein is conventional as to systemic medication, but can also be
local by using anticlotting or antiplatelet-coated miniball (or
stay) implants or local injection through a service-catheter
equipped with a hypotube at the distal end. Delivery that is
direct, targeted, and local allows the use of a much smaller dose
that not administered enterally or parenterally is distributed
minimally if at all to organs unamenable to the medication used.
Except for a slight narrowing taper toward the distal tip to
prevent the plug to be described from ejecting after the injectant
has been expended, the service-catheter is consistent in diameter
from end to end and fine enough to penetrate the lumen lining.
[4170] A separate hypotube extension, preferably made of a
nonmagnetic material, is inserted into the distal end of the
service-catheter only when the diameter of the service-catheter is
large enough in diameter that its distal end is not already
effecitvely a hypointimal or hypoendothelial needle and such that
the terminal taper must be too steep or long. Conventional diameter
reduction hypotubes for insertion into the distal end of larger
diameter service-catheters are obtainable from numerous suppliers,
to include IncisionTech Division, Specialty Blades, Incorporated,
Staunton, Va., for example.
[4171] A service-catheter passed down a service-channel can be used
to inject a wall-thickening (swelling) or tissue hardening agent
and/or any other kind of medication or a surgical cement prior to
discharge about a miniball after it has been placed. The
service-catheter is passed down a service-channel (spare
barrel-tube) as addressed immediately below and also below in the
sections entitled Muzzle-head Access through a Service-channel
without the Aid of and by Means of Inserting a Service-catheter and
Thermal Ablation or Angioplasty- (Lumen Wall Priming Searing- or
Cautery-) capable Barrel-assemblies.
[4172] A plug just to the rear of the injectant at the distal end
of the service-catheter 1. Prevents the injectant from flowing
proximad along the internal surface of the service-catheter as
would preclude control over dose delivery by adjustment in the
duration and pressure per puff of applied gas pressure. Since such
a plug also 2. Allows controlled or metered release of the
injectant and 3. Prevents the propulsive gas from emitting once the
injectant has been expended, it is applied despite the stabilizing
effect of surface tension and capillarity in service-catheter of
small gauge. If stored, the plug also serves to 4. Seal out
contaminants; the tip of the service-catheter is also dipped in a
sealant that to prevent allergic responses, may consist of any
suitable synthetic resin. The tip sealant should pull off in a
single piece for discarding when the service-catheter is to be
used. To prevent the loss of injectant when the tip sealant is
pulled away; the surface tension
[4173] The plug is produced by drawing up a suitable lumen-plugging
material while molten under suction just ahead of the injectant.
The coefficient of friction between the lumen lining and the plug
when molten and when solidified is set through the choice of tubing
and plug materials. When molten, the plug must ascend the
service-catheter under vacuum pressure controllably without
disintegrating and while maintaining a seal all about at a
temperature that will not alter the injectant. A suitable plugging
material must also be biocompatible and effectively insoluble in
the injectant. To avert the breakup of the molten plug as it
expands when drawn up the taper from the distal end, the taper is
kept to a minimum and a plug material used that has the necessary
cohesion. Upon solidifying, the plug must controllably slide down
the lumen ahead of the column of pressurized gas which it is seals
off from the substance to be injected to its fore and must be hard
enough to preclude being ejected through the distal end of the
service-catheter.
[4174] For procedures requiring the application of heat or cold,
the plug material must not significantly alter in flow or
frangibility at the temperatures to be used. For procedures that
require more than 85 degrees centigrade, most synthetic
(nonallergenic) waxes will not be usable as plugs, necessitating
the use of polymers. Once the molten plug material has been drawn
up into the distal tip of the service-catheter under vacuum
pressure, the tip is wiped flat and dipped into the substance to be
injected. This injectant is then drawn up into the lumen
continuously behind the plug, which is positioned level with a tick
mark so that the portion of the service-catheter between its distal
surface and the distal tip of the service-catheter will contain the
desired volume of injectant, such as medication, a swelling agent,
lubricant, or surgical cement, for example, contrast dye added for
enhanced imaging.
[4175] The calibration must allow for deformity in the front or
distal face of the plug and the taper at the tip that prevents the
plug from ejecting when the injectant is expended. The injectant is
delivered (advanced) by applying a puff of air or other gas. When
only one injection is to be made with the service-catheter, the
pressure and duration of the puff can vary over a range and thus be
applied by mouth, with a bulb, or syringe. When, however, the
service-catheter must deliver consecutive injections in the correct
dose without having to be withdrawn and another preloaded
service-catheter inserted for each injection, a precision
aspiration pump reversed to blow must be used to deliver puffs that
are metered in pressure and duration. When the application does not
necessitate exactitude, a conventional manual sphygmomanometer can
be adapted for the purpose.
[4176] XI17. Use of the Barrel-Assembly as an Aspirator or
Transluminal Extraction Catheter for the Removal of Soft Plaque or
Mispositioned Miniballs
[4177] Aspiration using a barrel-assembly is addressed above in the
section entitled Turret-motor Operational Modes. Once every
miniball has been implanted, rather than to withdraw the
barrel-assembly and introduce a separate aspiration line to remove
debris, the barrel-assembly can be directly bulb or syringe
pipetted or connected to a Beral pipette with bulb emptied or to a
vacuum aspirator. If provided with a side-socket as addressed below
in the section entitled Barrel-assembly Side-socket, the
barrel-assembly need not first be disconnected from the airgun.
Upon withdrawal following aspiration, the barrel-assembly can be
left connected to the vacuum pump, flushed with warm water, and
then sterilized with ethylene oxide gas, as addressed below in the
section on sterilization.
[4178] When the object is to retract debris and not to obtain a
biopsy sample, the use of a catheter to line the barrel-tube is not
essential. Except for use in the largest diameter ductus, to
incorporate additional components into the barrel-assembly as would
allow it to also function as an ultrasonic aspirator handpiece for
the fragmentation and emulsification of tissue currently exceeds
practical limits of miniaturization. Aspiration that uses the
barrel-tube or tubes as vacuum lines without a catheter must
immediately precede withdrawal or the debris retrieved will foul
the barrel-tubes. This is no less the case if the barrel-tube used
is a service-channel as addressed above in the section entitled
Muzzle-head Access by Means of a Service-channel. However, with
more than one barrel-tube available, the barrel-tubes can be
separately used as aspiration lines, service-channels, or for
discharging miniballs.
[4179] Then the barrel-tubes reserved as vacuum lines can be used
with the radial projection unit tool-inserts to remove material
from the inner surface of the ductus wall, after which barrel-tubes
not used thus can be used for discharge. For the most part, the
incorporation of plural barrel-tubes is limited to
barrel-assemblies of larger diameter. A barrel-tube used as an
aspiration line can serve as a means in addition to the recovery
electromagnets and trap-filter for recovering a mispositioned
miniball. Yet another method for the recovery of implants whether
miniballs or stays is addressed above in the section entitled
Non-endoluminal Recovery of Miniballs To recover a miniball, the
closest muzzle-port is placed over the intima at the point where
the miniball penetrated the ductus wall and the vacuum applied.
[4180] Preferably this will back out the miniball through the same
angular trajectory as it entered, retrieval thus rather than normal
to the trajectory end-point less injurious to the inner layers of
the ductus wall. Since the inclination of the barrel-tubes is that
used to discharge the miniball, placing the muzzle-port over the
entry perforation results in the application of the retractive
force at the same angle as the entry trajectory. Wetting the
miniballs in the rotary magazine clip with contrast before
inserting the clip into the chamber aids in locating the insertion
perforation. If miniball recovery is sufficiently free of
line-fouling debris, as can be accomplished when different
barrel-tubes were used for the aspiration of debris, then once
retrieved into the barrel-tube, the barrel-tube can be removed from
the vacuum line and reconnected for discharge to reposition the
miniball within the ductus wall.
[4181] XI18. Use of the Barrel-Assembly as an Aspirator or
Transluminal Extraction Catheter to Retrieve Biopsy Samples
[4182] Apart from implant delivery, any barrel-assembly can be used
to obtain tissue samples for analysis from along the inside of the
lumen wall, eliminating the need for entry more than once. For such
use, a vacuum pump can be connected directly to a barrel-tube or
bulb or syringe pipetting or a syringe can be used. However, in
most instances, the treatment site will not allow a vacuum pressure
sufficient to retract the tissue without the need to withdraw from
the lumen. Unless this is the only or the last procedure to be
performed, it is desirable to leave the barrel-assembly in position
and avoid the need for a forced withdrawal. This is accomplished by
using the barrel-tube as a guide-catheter or conduit for slightly
narrower catheters.
[4183] The sampling catheters withdrawn as desired, aspiration then
need not draw tissue more than a few millimeters into these. The
use of service-catheters to withdraw ablated tissue and samples for
analysis can be combined with use of the radial projection unit
tool-inserts to remove hardened (indurated, sclerotic) or toughened
tissue more quickly, as addressed below in the sections entitled
Coordinated Use of Aspiration and Piped Radial Projection and
Radial Projection Unit Tool-inserts. Additional means for obtaining
biopsy samples is the use of a piped radial projection tool-insert,
as addressed below in the section entitled Coordinated Use of
Aspiration and Piped Radial Projection Units to Remove Dseased
Tissue or Obtain Tissue Samples for Analysis.
[4184] X119. Rotation of Muzzle-Heads with Unused Barrel-Tubes for
Use as a Guide-Catheters
[4185] With a single barrel-tube, such as in a simple pipe or a
monobarrel radial discharge barrel-assembly, use of the
barrel-assembly as a guide-catheter for different procedures, such
as the delivery of medication, taking of biopsy samples,
application of heat or cold, for example, must be done in
succession. The insertion and withdrawal of catheters one at a time
down a single channel takes more time, but the lack of sufficient
lumen diameter can impose this limitation. A multiple barrel-tube
barrel-assembly allows each barrel-tube to serve as a
guide-catheter for a different procedure.
[4186] For example, one barrel-tube can be used for atherectomy by
means of suction ablation and another to apply medication in the
form of a gas, powder, or liquid, or to apply heat or cold, in any
sequence, to include alternation between ablation and medication
and alternation to change the medication. With a multiple
barrel-tube barrel-assembly, the turret-motor can be used to rotate
successive catheters into position without the need to withdraw one
catheter and insert another, so that switching from one catheter to
the next is accomplished immediately. A larger diameter barrel-tube
allows the use of a bioptome.
[4187] Since in order to prevent distortion of the barrel-tubes to
an extent as would interfere with discharge, the muzzle-head
incorporates a detent to prevent excessive rotation, the use of
separate barrel-tubes to convey catheters for accomplishing a
different but related treatment option with each is best performed
with an eccentric muzzle-head wherein the exit ports are closer
together than in a muzzle-head with an equidistant configuration.
This allows related functions to be quickly applied in a prescribed
sequence. Since the use of each catheter is sequential, the fact
that aiming each successive exit port with the manual means
provided more accurately than within a quadrant of the ductus
circumference is of nugatory pertinence. Greater aiming accuracy is
obtained through the use of contrast and adequate imaging
technology.
[4188] XII10. Delivery of a Measured Quantity of a Liquid Through a
Service-Channel
[4189] A catheter for delivery of a liquid, such as a medication,
surgical cement, or a mixture of diverse substances through a
service-channel is provided by inserting syringe thumb plunger with
a plunger shaft calibrated in milliliters into the proximal end of
the catheter, dipping the distal end of the catheter into the
liquid, and using the plunger to draw in a measured quantity of the
substance through the distal end of the catheter. The calibration
is then used to eject the desired amount. A similar calibration at
the distal end can be used to confirm delivery of the desired dose
after withdrawal. The application of a liquid through or upon the
intima within the vascular tree requires that the substance be
innocuous, that it not enter the bloodstream in medically
significant amount, or that the clinical context justifies the
risk. The use of a trap-filter is addressed above in the section
entitled Cyanoacrylate Injection Catheter. Depending upon the
medication and the caliber and length of the service-catheter, a
high pressure metered dose inhaler or an electronic or jet
nebulizer (atomizer) can be connected to the service-catheter to
deliver the medication as an aerosol.
[4190] XII11. Delivery of a Measured Quantity of a Gas Through a
Service-Channel
[4191] The metered release of a gas through a catheter that is
passed down a service-channel to abut upon the target tissue along
the internal surface of the lumen is by means of a modified
commercial gas-operated pistol as described below in the section
entitled Modification of Commercial Airguns. The air pistol is
connected to the catheter in the same manner as it would be
connected to a simple pipe barrel-assembly, for example. When not
liquified CO.sub.2 to chill the target tissue, the compressed gas
in the cylinder must have eliminated any lubricant as may have been
incorporated into a conventional powerlet as to consist of or
include the therapeutic gas to be delivered (which will be
liquified only if the boiling point is below the room temperature).
Regardless of phase transition, the gas is delivered from a
pressurized canister.
[4192] In a commercial air pistol suitable for use with a simple
pipe barrel-assembly when modified as described below in the
section entitled Simple Airgun with Limited Application, the
medicating gas expelled with each discharge is determined by the
gas pressure, the valve body open time, and the the cross-sectional
area of the gas passage or circular aperture surrounding the pin
through the valve. The spring-loaded valve body pin generally
conical, aperture area and open time depend upon the force of
impact by the hammer, pin conformation, and the restorative force
of the valve body spring.
[4193] These built in factors inherently meter the gas discharged
with each pull of the trigger, the valve body slide valve
modification described below in the section entitled Dedicated
Interventional Airguns allowing variability in the valve body
pressure. In the more versatile embodiments described in the
section below entitled Dedicated Interventional Airguns, the
incorporation of a punch solenoid in place of a spring loaded
mechanical hammer affords a means for controlling valve body open
time in addition to the slide-valve incorporated into the side of
the valve body. Adjustment in the solenoid current varies the force
of impact, hence, the excursion of the valve body pin when
struck.
[4194] XII12. Delivery of a Measured Quantity of a Powder Through a
Service-Channel
[4195] Therapeutic dry powders, aerogel powders, and aerosol
delivered powders encompass a wide spectrum of medication types
(see, for example, Claim 22, Lechuga-Ballesteros, D. and Kuo, M-C.
2003. "Dry Powder Compositions Having Improved Dispersivity," U.S.
Pat. No. 6,518,239; Lee, K. P. and Gould, G. L. 2006. "Aerogel
Powder Therapeutic Agents," U.S. Pat. No. 6,994,842). Methods for
achieving uniformly dispersible powders for pulmonary drug delivery
that can be adapted for delivery through a catheter continue under
development (see, for example, Lechuga-Ballesteros, D., Charan, C.,
Stults, C. L., Stevenson, C. L., Miller, D. P., Vehring, R., Tep,
V., and Kuo, M. C. 2008. "Trileucine Improves Aerosol Performance
and Stability of Spray-dried Powders for Inhalation," Journal of
Pharmaceutical Sciences 97(1):287-302 and
http://www.nektar.com/pdf/dried_powder.pdf; Seville, P. C., Li, H.
Y., and Learoyd, T. P. 2007. "Spray-dried Powders for Pulmonary
Drug Delivery," Critical Reviews in Therapeutic Drug Carrier
Systems 24(4):307-360; Louey, M. D., Zijlstra, G. S., Hinrichs, W.
L. J., de Boer, A. H., and Frijlink, H. W. 2004. "The Role of
Particle Engineering in Relation to Formulation and
De-agglomeration Principle in the Development of a Dry Powder
Formulation for Inhalation of Cetrorelix," European Journal of
Pharmaceutical Sciences 23(2):139-149; Van Oort, M., and Hickey, A.
J. 2004. "Aerosol Dispersion of Respirable Particles in Narrow Size
Distributions Produced by Jet-milling and Spray-drying Techniques,"
Pharmaceutical Research 21(7):1200-1206; Platz, R. M., Kimura, S.,
Satoh, Y-I., and Foster, L. C. 2000. "Methods and Compositions for
the Dry Powder Formulation of Interferons" U.S. Pat. No.
6,123,936).
[4196] To avoid the risk of gas embolism, the endoluminal
application of a gas or gas-propelled powder, albeit small in
volume and directed into as to be substantially contained within
the lumen wall, is substantially limited to use outside of the
vascular tree. This is true even when delivery of a dry powder
through a finer catheter to a considerable distance that
necessitates higher pressure is uninvolved. A dry powder inhaler of
conventional design does not generate the propulsive force required
to move the powder down the catheter and therefore requires a to be
adapted by incorporation into the supply line of a ventilator.
[4197] A larger sized precedent applied to an endotracheal tube of
9 millimeters in internal diameter having already been described in
the literature (Everard, M. L., Devadason, S. G., and Le Souef, P.
N. 1996. "In Vitro Assessment of Drug Delivery Through an
Endotracheal Tube Using a Dry Powder Inhaler Delivery System,"
Thorax 51(1):75-77), only miniaturization is necessary for use with
a service-catheter. When some of the powder adheres to the proximal
internal surface of the catheter with each actuation, the number of
times that this apparatus can be used without the need to replace
the catheter will be limited by the accumulated buildup of powder
along the inside of the catheter walls. The actual number of
actuations needed in a practical procedure should only rarely
necessitate replacing the catheter.
[4198] XII13. Midprocedural Delivery of Lubricant to the
Muzzle-Head
[4199] If despite the measures incorporated to minimize such an
eventuality, adhesion of the muzzle-head to the endothelium occurs,
a hypodermic syringe is used to inject lubricant into the proximal
end of a barrel-tube or tubes used as a distal access barrel-tube
as described above in the section entitled Muzzle-head Access by
Means of a Service-channel, and a ramrod or test rod used to push
the lubricant out through the muzzle-port. Rotation with the
turret-motor as preferred for controllably minimizing the
rotational displacement or by hand is then used to work the
lubricant around the muzzle-head. A felt or cotton-coated ramrod is
then used to remove any residual film from the walls of the
barrel-tube or tubes.
[4200] XIII. Airguns
[4201] XIII1. Operational Requirements
[4202] From one distance along the ductus to the next, the tissue
of a lumen wall can be either substantially uniform in mechanical
properties, as is usually true of the subacute or pre-Grade IV
collapsed trachea, or variable, as when vascular disease has
differentially affected different portions of the arterial or
venous wall. For the trachea, which is relatively large in internal
diameter, a single miniball discharging airgun is appropriate. In
the trachea, the miniballs are implanted along a dorsolateral
longitudinal line in relation to the cartilage rings, relatively
seldom at other points about the lumen circumference, and the
working space afords maneuverability. In advanced collapse where
secondary inflammation and infection may have alterred the
mechanical properties of the tissue, miniballs of one kind are
implanted in one pass, and those different in a second pass.
[4203] Alternatively, if distinctions in mechanical properties of
the tracheal tissue are present due to a different level of
expression of primary pathology or due to independent, or
trans-nosological, comorbidity with areas that exhibit various
conditions, then the single-shot airgun load queue can be strictly
sequenced according to a prescribed load list to include miniballs
of different mass coated with different medications. Of these
approaches, the first is to be preferred as minimizing the need for
frequent adjustment of the airgun propulsive force resulting in a
longer operation with increased possibility of errors. Because the
barrel-assembly will obstruct blood flow, the time of any procedure
in arteries, the coronary arteries in particular, is acutely time
sensitive. While in the bloodstream, the barrel-assembly must not
be discharged unloaded.
[4204] Unlike the rotary magazine clip which makes it possible to
apply a consistent propulsive force to miniballs that differ in
mass by means of securing each miniball in its clip hole with a
dried solution or syrup of sugars, corn starch, or molasses
(treacle) of a formulation and thickness to offset the lesser
resistance to expulsion of any miniball or miniballs in a set to be
discharged together, a single-shot airgun must be adjusted in
propulsive force every time there is a change in the mass of the
miniball to be ejected. With a rotary clip, the propulsive force
may have to be varied with the sum of miniball masses. The solution
or syrup is run about the groove formed by the perimeter of the
miniballs and rotary clip holes by surface tension, and to prevent
debris from moving down the barrel, the composition of this
adhesive should have good self-adhesion.
[4205] Except in hole pattern, which is generally for a group of
miniballs rather than one, the rotary magazine clips are
conventional. Except in the circulatory system, where once
introduced the one barrel-assembly, even though demanding
adjustment for different miniballs, should not be removed and
replaced, changes in miniball mass are accomplished by withdrawing
the barrel-assembly and introducing one of another airgun.
Alternatively, the barrel-catheter can be removed and one of
different caliber connected to a second airgun of like caliber.
While prior to fixation of the miniball within the rotary clip ring
hole and as a separate operation, medication can be applied in a
sugar or syrup coating that has been heat- or freeze-dried, the
miniballs are produced to meet such special requirements.
[4206] The construction of the airgun includes a conventional
rocker-arm stop that prevents the premature entry of a miniball
into the barrel at the same time that it prevents a second miniball
from partially entering the chamber before the chambered miniball
has been expelled. A single `shot` semiautomatic airgun can be
queued with miniballs of like caliber but different mass, but were
differences in mass to exceed the range over which the impact force
would implant the miniball subadventitially without unacceptable
under- or overshooting, the procedure must be interrupted to adjust
the propulsive force. To adjust the single `shot` airgun after one
or a few discharges, is, however, not recommended as contrary to
minimizing operative time; to minimize the number of adjustments,
hence time necessary, all implant discharges of like mass are
completed before proceeding to miniballs of different mass.
[4207] Using a simple airgun, the propulsive force can be adjusted
after the complement of miniballs of like mass have been implanted
or the barrel-assembly, which in the trachea consists of a simple
catheter pipe barrel, is left in the patient, and the proximal end
of the barrel-assembly is detached from the airgun and inserted
into another airgun preadjusted to discharge miniballs of different
mass. To change the caliber, however, requires withdrawing the
barrel-catheter and inserting another of the new caliber. The same
airgun can be adjusted or another already connected to the
barrel-catheter can be used. Using a single shot airgun, the more
complicated matters of mixing miniballs of different mass in a
single shot as differentially distributing the propulsive force
does not arise, because the airgun is not capable of multiball
discharge.
[4208] At the extreme of demand is the diseased coronary vessel
where to avert the risks posed by interruption in the circulation
much less the use of a heart and lung machine, the time of the
procedure must be kept to a minimum under considerably more
difficult working conditions. This justifies the expense of certain
refinements that make it possible to discharge multiple miniballs
simultaneously in a radial pattern, to do this with quick
repeatability, and to change the exit velocity to a value desired
quickly by alternative means of control used individually or in
combination. This is accomplished by a radial discharge muzzle-head
that delivers a plurality of miniballs, usually four, one each into
each quadrant of the circumference. The requirement to vent the air
inside the barrels with the muzzle-head immersed in the bloodstream
without introducing any gas into the bloodstream precludes the use
of side holes as allow the blood to continue to flow if obstructed
in guide-catheters.
[4209] Such an airgun is loaded by inserting the miniballs in a
rotary or wheel magazine clip, that indexes the miniballs into
`firing` position in front of the propulsive gas outlet. The
barrel-assembly built as an integral unit, and the muzzle-head
usually radially symmetrical in internal structure, the caliber of
the barrel-tubes and their respective muzzle-head exit ports in any
one muzzle assembly are the same, even though specialized rotary
magazine clips and barrel-assemblies could be made to combine
different calibers in each discharge. Any change in the caliber or
mass of one or more miniballs in the set to be discharged together
must be offset by adjusting the resistance to propulsion of each
miniball by changing the consistency of ingredients of a
quick-dried syrup used to hold or clinch the miniballs in the
rotary clip holes.
[4210] Every rotary magazine clip loaded into the airgun should be
visually inspected and lightly shaked to be certain no minball is
loose. Vigilance exercised, premature entry of a miniball into a
barrel is unlikely to result from looseness in the rotary clip
hole, but rather because of imperceptible inequalities in the clip
hold retentiveness of the miniballs of a set to be discharged at
the same time, which can allow the propulsive gas to leave
chambered or dislodge miniballs other than one offering critically
less resistance. The improper apportionment of resistance to
expulsion is minimized though rigorous testing and tight quality
control. The miniball is retrieved by disconnecting the
barrel-assembly from the airgun and passing a mildly magnetized
guidewire down the barrel-tube.
[4211] The calibers of the miniballs in a given rotary magazine
clip and the barrel-assembly must match, individual discharges that
include miniballs different in caliber requiring the use of a
special purpose clip and barrel-assembly to match these in caliber.
Differences in mass for any reason, to include the addition of an
outer layer to deliver medication or radiation, can be accommodated
in single discharges. Since the propulsive gas will find the path
of least resistance, miniballs of less mass must be equalized in
clip hole retention by syrup bonding. Simultaneous discharge
assumes that the distinction in mass is negligible; if the
difference in mass is significant, the more massive miniball may
not be propelled at all. The parallel use of different airguns to
propel the miniballs in the different holes of the discharge set is
not contemplated.
[4212] Reloading by inserting a new rotary clip or by detaching the
barrel-assembly from one airgun and inserting it into another can
be done quickly. To change the caliber, however, requires
withdrawing the barrel-assembly and introducing another, and this
negates the practicality in an airgun with multiple output ports or
barrel-assembly fittings of different caliber. With the
barrel-assembly exchanged, a rotary clip containing miniballs of
different caliber can be inserted in the same airgun.
Barrel-assemblies and rotary clips can be produced to discharge
from one to four or more miniballs in a radial pattern. The ability
to produce barrel-assemblies and matching rotary clips other than
radially symmetrical increases the lower is the number of barrels
or barrel-tubes.
[4213] In situations where the number of miniballs to be discharged
at a time changes, proceeding with the barrel-assembly already in
position is preferable to withdrawal and insertion of another.
Changing the number of miniballs to be discharged at once is
physically similar to differences in mass among a complete set,
which likewise differentially distributes the sum propulsive force.
In this case, however, the difference in mass will require an
adjustment in propulsive force, which may take the form of
adjusting the airgun in use or switching to an airgun preset to the
required value. When the number of miniballs to be discharged at
one time is less than the number of barrel-tubes in the
barrel-assembly, a miniball mounting hole on the rotary clip is not
left vacant but rather reduced in diameter to bring the force
applied to the miniballs that are present to a sum value within the
range that this would have been were a miniball present.
[4214] XII12. Modification of Commercial Airguns
[4215] Certain air pistols modified as specified below are loaded
or fed miniballs from a line-feed type magazine clip. These are
limited in use to single miniball or monobarrel discharge,
specifically, simple pipe and single miniball radial discharge
barrel-assemblies. An airgun that uses a rotary magazine clip can
accept any barrel-assembly whether a simple pipe or a multibarrel
radial discharge barrel-assembly. A modified commercial air pistol
allows use of a simple pipe, and thus low implant density magnetic
stenting and the targeted placement of medication miniballs within
the ductus wall with injury limited to the diameter of the miniball
trajectory and at minimal expense. A monobarrel is adequate for any
application that calls for the discharge of no more than one
miniball at a time.
[4216] The trachea and bronchi, which present differentiated
anatomy, are best treated with a readily aimable simple pipe, or if
too small in diameter, a radial discharge monobarrel, which is
essentially a simple pipe with a wrap-around protective jacket, is
suited for use in any ductus that is too small in diameter to admit
a simple pipe. The tracheal collapse encountered in veterinary
practice is often associated with bacterial infection; while an
angioplasty-capable radial discharge barrel-assembly could be used
to introduce an antibiotic directly into the diseased tissue, the
proclivity of bacteria toward dispersion recommends systemic
administration. Even the simplest pipe-type barrel-assembly must
include a recovery electromagnet close to the exit-hole or
exit-portal in the muzzle-head.
[4217] When not obtrusive or adding significant weight, the battery
is preferably contained within the electromagnet housing and the
control knob at a proximal or extracorporeal position on the
barrel-catheter. The barrel-assembly can be provided with a
slidable and removable power and control housing as a radial
discharge-type barrel-assembly, but this adds much cost without
justification, positioning the battery and control on the pistol
equally functional. The battery is usually added at the bottom of
the pistol grip and the control knob at the side of the chamber,
the electrical connection made to avoid the gun barrel as shown in
FIG. 75. Rather than using an electrical plunger switch as the
trigger, a modified commercially available air pistol (hand airgun,
air handgun) uses the original mechanical triggering mechanism.
[4218] The battery is attached as a downward extension of the
pistol grip, with a potentiometer and knob for adjusting the
current through, hence, the field strength of the tractive recovery
electromagnet, attached to a control panel mounted to the inner
face of the grip. Alternatively, the potentiometer can be mounted
along the slide, or lacking a slide, the corresponding location,
and a three-way toggle switch with fixed settings for recovery
magnet off, recover (a dropped miniball), and extract (a
mispositioned miniball) used in lieu of the continuously variable
potentiometer. Modified air pistols for use with minimally ablation
or ablation and angioplasty-capable barrel-assemblies must have a
control panel that includes any controls needed to operate any
additional features of the barrel-assembly, such as radial
projection units or an embolic filter.
[4219] The first of the two modified commercially available air
pistols now to be described uses a queue or linear sequential
spring-loaded clip and is therefore suitable for use with
monobarrel barrel-assemblies whether of simple pipe or radial
discharge type. The more capable air pistol to follow achieves
greater versatility by virtue of incorporating a rotary magazine
clip, which allows either a single or a number of miniballs to be
discharged at one time and thus the ability to support either a
monobarrel or multibarrel tube barrel-assembly. Additionally, a
rotary magazine clip type airgun allows the portion of the airgun
overlying the chamber to be removed and replaced with transparent
plastic allowing the failure of one or more of a set of miniballs
to be discharged at once to be seen.
[4220] However, the discharge mechanism of an airgun that loads
queued miniballs one at a time is incapable of multiple miniball
discharge, and the failure of a single miniball to discharge would
be immediately evident without such viewability. A rotary clip
makes possible the projection of multiple miniballs per discharge
and therewith. Whereas the successful projection of a single
miniball is instantly evident, the failure of one of four to be
propelled is not. Fluoroscopy and angioscopy used to confirm the
placement of miniballs, it is additionally helpful to have the
chamber retrofitted with a roof made of a suitable transparent
polymer such as polycarbonate. This allows inevidence of a miniball
to implant properly to be immediately traced to a failure within
the airgun rather than loss in the patient.
[4221] XIII2a. Simple Airgun Modified to Allow Limited
Application
[4222] The barrel-catheter in a simple pipe being the one
barrel-tube, no course through the interior of the barrel-catheter
or along the outer surface of the barrel-catheter to be inserted
into the airgun is available for running the conductors for the
recovery electromagnet. Since the external surface of the simple
pipe comes into contact with the airway lining, the simple
pipe-type barrel-assembly must not present any sharp edges or
protrusions. The electromagnet in the muzzle-head is therefore
connected to the battery mounted at the bottom of the pistol grip
by fine wires attached to the outside of the barrel-catheter by
means of a nonallergenic adhesive having the consistency of caulk.
Since the recovery electromagnet wires and any bounce-plate device
in addition to a viewing device must not be inserted into the
airgun barrel, fiberoptic connections are made as shown in FIG. 75,
circumventing the airgun barrel.
[4223] Barrel-catheter tube stock of sufficient thickness allows
the countersinking of a wire-way with connection inside the chamber
comparable to that depicted for a radial discharge barrel-assembly
in FIGS. 72 and 74. Energization of the electromagnet is similar to
that described above in the section entitled Stay insertion tools.
The primary object in such an embodiment is to provide veterinary
specialists with a simple and relatively inexpensive hand-held
airgun that with suitable imaging equipment and a barrel-assembly
with clearly visible markers can be used to ameliorate the
intermittent asphyxia (suffocation) or airway throttling
symptomatic of collapsed trachea in small dogs without the need for
a thoracotomy.
[4224] The simplest airgun usable with the methods described herein
delivers one miniball per discharge and connected to a simple pipe
barrel-assembly, is suitable only for procedures in structures such
as the trachea, while connected to single-barrel radial discharge
barrel-assembly or monobarrel, is suitable for use in closed ducts
and vessels. Ductus that are relatively large in diameter and open
to the exterior afford greater accessibility and maneuverability
but exhibit differentiated histological and anatomical structure.
Speed in the airway must always remain consistent with a distinct
aiming capability. The lumen of a closed vessel that is
additionally diseased is accessed with relative difficulty, affords
significantly less maneuverability, and is substantially
undifferentitated with respect to its normal condition.
[4225] The closed vessel therefore poses the opposite set of
factors for attaining operative speed. For the latter, speed that
comes with multiple simultaneous radial discharge of miniballs in
rapid succession. A modified airgun of the queue loaded or line-fed
type is not suitable for applications in the vascular system where
the ductus is closed to the exterior, the lumen diameter is usually
two or three millimeters, and the disruption to the delivery to the
cells of oxygen by the circulation calls for completion of the
procedure in the least amount of time. A single shot per discharge
semiautomatic repeat action airgun can be provided by modifying an
off-the-shelf or commercially available hand airgun in bore to
project small caliber miniballs and allow the propulsive force to
be variably controlled.
[4226] Of airguns currently available, the Daisy 93/693 is suitable
as clip-loading 15 shots, minimizing interruption for reloading
midprocedure and as not presenting a reciprocating slide to
interfere with the addition of a permanently positioned control
lever. The break breech design also makes the insertion of a
testing rod shortly to be described simpler, the rod inserted at
the back of the barrel, making insertion of the key easier. Change
to the bore can be effected by placing a sleeve inside the barrel
to reduce the internal diameter or by increasing the thickness of
the barrel-catheter. The use of a sleeve is preferred as not
affecting the barrel-catheter flexibility, hence, material. The
chamber must also be adapted for the smaller caliber. Such an
airgun can be provided by modifying an off-the-shelf or
commercially available semiautomatic repeat action single miniball
discharge hand airgun to project small caliber miniballs.
[4227] The modification of commercially available airguns must be
carried out by trained personnel in a special facility subject to
stringent quality control. Such modification is discussed with
greatest applicably in generic terms, actual models available being
many, differing in inconsequential details, and constantly subject
to discontinuation, while new models are frequently introduced.
There are two major types of off-the-shelf or commercially
available single miniball discharging hand airguns or air pistols,
the first made to discharge gauge BB ball shot, the second pellets.
Both kinds accomplish repeat action semiautomatically, the first by
admitting or feeding one miniball at a time into the chamber from a
queue or line contained within a spring-loaded loading clip into
the chamber by the action of the preceding discharge.
[4228] A conventional rocker check-arm prevents the entry into the
chamber (but not the barrel-tubes) of more than one miniball at a
time. The adaptation of higher power airguns allows higher exit
velocities for sclerotic and resistive tissue, such as that
considerably calcified or ossified in patients for whom resection
or excision is inadvisable. The higher propulsive force of such
airguns is readily reduced to any lesser force by bleeding off the
propulsive gas as will be described or by increasing the rolling
resistance. No suggestion is intended that less forceful airguns,
referred to as `airsoft` or `softair,` or that use the force of a
spring to propel the spherule or `BB,` or that are used to play
paintball cannot be adapted for applications that demand impact
forces less than the maximum for the airguns specified.
[4229] Representative of the many spring-clip line-fed miniball
hand airguns are those manufactured by Maruzen Kabushiki Kaisha
according to the specifications of and sold by the Daisy Outdoor
Products Company. That bearing model number 15XT requires loading
the miniballs one at a time; model number 93 since discontinued;
and model number 693, now redesignated model number 93/693, which
is clip loaded, and the Crosman-Walther PPK/S, all semiautomatic
4.5 millimeter (0.177 caliber) and powered by a 12 gram CO.sub.2
cylinder (canister, cartridge, tank), which the manufacturer will
refer to as a `powerlet` or `pistolet.` An advantage of using the
spring-loaded line feeding type clip to chamber successive
miniballs semiautomatically, airguns designed to discharge
miniballs rather than pellets are capable of a larger number of
successive discharges or `shots` without reloading, typically
fifteen.
[4230] Some makes or models of line-fed or spring loaded linear
queue type magazine clip loaded miniball hand airguns, such as the
Industrias el Gamo V3, also semiautomatic, 4.5 millimeter (0.177
caliber), and 12 gram CO.sub.2 cylinder-powered, incorporate a
triggering mechanism that to simulate the appearance and action of
an actual automatic pistol firearm, includes a reciprocating slide
that travels over the valve body and chamber, which are integral to
the clip at the top thereof, the valve body above the gas cylinder
and the chamber above the miniball queue. This slide does not
preclude the retrofitting of a simple low-cost control mechanism
presenting a lever to the outside of the airgun to allow the
propulsive force or exit velocity to be adjusted without the need
to remove the clip; however, because two layers of plastic slide
past one another, the view into the chamber even with transparent
material is obscured.
[4231] The modification of any commercial airgun includes the
mounting to the front end of the muzzle of a barrel-assembly
connecting socket as described above. To modify the Gamo-type
mechanism is more difficult than the models that do not have a
reciprocating slide. Daisy model 15XT has no reciprocating slide
making it easier to modify, but unlike Daisy model 93/693, is not
clip loaded, instead requiring that the miniballs be loaded one at
a time, effectively necessitating that several be preloaded for any
one procedure. Clip loaded and lacking a slide, Daisy model 93/693
is superior for use with a simple pipe barrel-catheter for
tracheobronchial procedures. While it is easily within the
capability of a rotary magazine clip airgun to be described, to use
different caliber miniballs with one and the same spring-loaded
queue fed airgun would require changing the inserts throughout the
miniball delivery path inviting inaccuracy and malfunction. Such a
low cost embodiment is preferably sold as permanently modified for
use with a fixed caliber not to be changed by the purchaser.
[4232] XIII2b. Simple Airgun Modified to Allow Wider
Application
[4233] The second type of airgun, some originally made to shoot
pellets, uses a rotary magazine or wheel clip that typically
provides fewer discharges than the line-loaded type clip, typically
six successive `shots` or discharges, before a spent clip must be
replaced with a loaded one; however, replacing a spent rotary clip
takes but a moment. Modified as described below, the rotary
magazine clip can be used to discharge from one to four or more
miniballs per discharge, making it considerably more versatile for
realizing the objects stated above. As previously described, using
either type of clip, different miniballs can be variously coated to
deliver medication or radiation. A means for adapting either a
spring-loaded queue or a rotary magazine clip type airgun with a
testing mechanism is described under the heading `universal means
of testing` that follows.
[4234] Rotary clip airguns made in the form of rifles rather than
handguns generally use rotary magazine clips that typically hold
twelve pellets, and therefore use rotary magazine clips that are
larger in diameter, affording a larger number of multiple miniball
discharges and reducing the frequency of reloading regardless of
the fact that custom clips are used. An example is the Crosman
Model 1077, likewise semiautomatic, 4.5 millimeter (0.177 caliber),
and powered by a 12 gram CO.sub.2 cylinder, with an AirSource.RTM.
adaptor available for 88 gram (3.1 ounze) AirSource.RTM. cylinders.
Yet other airguns, such as the model 617X made by Maruzen Kabushiki
Kaisha according to the specification of and sold by the Daisy
Outdoor Products Company, are available that are capable of
shooting either miniballs or pellets, the added capability due to
the mere incorporation into the rotary clips of a slight
circumferential ridge to prevent miniballs from rolling out into
the barrel before discharge.
[4235] All airguns that are able to discharge either pellets or
miniballs use rotary clips that hold either miniballs or pellets of
like caliber; none changes the repeat action to switch from clip
rotation to discharge pellets to fixing the rotary clip in position
for the opening aligned to the valve body outlet to serve as a
miniball chamber. Daisy model number 622X, which shoots 0.22
caliber pellets, is identical to Daisy model number 617X, which
shoots 0.177 caliber pellets or miniballs using the same rotary
clips, and except for the fact that the rotary magazine clips
supplied for the 622X lack a slight circumferential ridge at half
the distance through the bore, would be equally able to shoot 0.22
caliber miniballs using the same clips. Provided with a slightly
larger caliber, the 622X also uses clips that larger in diameter,
afford greater latitude in the multiple miniball sets per discharge
and caliber of the miniballs that can be accommodated in the custom
rotary magazine clips to replace the original.
[4236] The following description of the modifications essential to
make a commercially available airgun suitable for the repair of
tracheal collapse by veterinarians as previously described
presupposes a semiautomatic repeat action hand airgun wherein the
miniballs are successively forced up into the chamber by a
spring-loaded line-feed clip. To this end, the models specified
above are mentioned in a purely exemplary sense; similar airguns
produced by several manufacturers exhibiting much the same
construction and capable of being modified to serve the present
object equally well. Modification of the existing hand airgun is
accomplished by placing caliber-reducing polytetraflouroethylene
tube inserts in the spring-fed clip and barrel, and a
caliber-reducing lining plugged into the chamber loading tube,
which is situated toward the forward end of and integral with the
clip.
[4237] The clip insert requires that the spring and plunger that
drives the line of miniballs upwards into the chamber when the
rocker arm lifts be replaced by proportionately smaller versions.
Reducing the caliber from the original 4.5 millimeters to 1.0
millimeter, for example, increases the number of miniballs that can
be loaded from 15 to 67. The number of cartilage rings in the dog
trachea being 40 plus or minus 5, an extensive procedure
necessitates reloading twice. The quickest way to accomplish this
mid-procedure is to disconnect the barrel cathether from the airgun
without removing it from the patient and reconnecting it to another
fully loaded airgun, whereupon the first airgun is reloaded. A
smaller hole through which to reload miniballs and a side slot to
return the spring and allow the number of miniballs loaded to be
seen must be cut into this tube, which is positioned concentric to
the original loading hole or entry into the chamber at the top of
the chamber loading tube.
[4238] If the wall thickness of the inserts placed in the barrel
and miniball feeding channel in the spring-loaded line-feed clip in
the grip does not center these as concentric within the original
diameters, then tape is used at intervals along the length about
the circumference to achieve a snug fit. Alternatively thin sheet
of a polymer with a low coefficient of friction such as
polytetraflouroethylene can be wrapped about the insert tubing to
avoid the bunching up at the entry experienced with other
materials. The barrel insert tubes used to reduce the caliber of
the barrel stops half way down the barrel to allow the proximal end
of the barrel-assembly to be inserted. The insertion of the
caliber-reducing polytetraflouroethylene tube insert in the barrel
covers over the rifling. The chamber insert lining properly centers
the smaller miniball in relation to the propulsive gas entry hole
directed to its apex at the rear, the miniball entry hole in the
chamber floor, and the barrel to the fore.
[4239] The small finger at the top of the loading spring that
pushes the last miniball up into the chamber through the floor must
be replaced with one that is longer to pass the smaller miniball up
through the hole in the chamber floor which has been made thicker
by the lining. The original rocker check arm that admits only a
single ball into the chamber at a time at the front bottom of the
chamber must be removed and replaced with another proportionately
smaller in size in the equivalent position to lap over the exit or
muzzleward hole floor drop off at the center front of the chamber
insert lining. The chamber insert lining has a hole at the center
of the rear through which the propulsive gas is released from the
valve body directly against the rear of and causing the miniball to
travel down the barrel. This hole is proportionately smaller than
the original hole behind it, the two holes positioed in flush
concentric relation.
[4240] The small CO.sub.2 cylinder or canister that fits into the
clip adjacent to the spring-loaded miniball feed line is engaged by
forcing it up against a hypodermic -type inlet pipe of the valve
body at the bottom thereof by means of a screw beneath the
cylinder. This connection by intromission affords no junction as
would allow the insertion of a valve or regulator. This leaves the
components that affect the propulsive force after the propulsive
CO.sub.2 has entered the valve body and chamber to introduce means
for adjusting the propulsive force and therewith the exit velocity.
Of the various means for effecting a reduction in the exit velocity
in such a retrofit of a manufactured airgun, examined from the
standpoint of greatest simplicity have been reducing the delivery
of propulsive gas from the valve body as affected by the time and
force of depression of the valve pin by the hammer.
[4241] Others have been to effectively increase the volumetric
dimensions of the valve body and so reduce the pressure inside of
it by means of a bleed slot continuously variable in area, a
similar slot cut into the chamber, and lengthening and curving the
barrel-assembly to increase rolling resistance disproportionately
to the increased propulsive force of the extention in barrel length
represented by the barrel-assembly. Of these possible points of
interception to obtain the control necessary, replacing the hammer
with a reciprocating armature (plunger, punching, push-type)
solenoid of which the striking force and time is variable and
introducing a bleed opening with adjustable cover in the chamber
have been discounted as needlessly complex and costly in a modified
airgun intended to be merchantable at relatively low cost.
[4242] The former is employed in more precise multipurpose
embodiments originally produced to obtain the present objects, and
the latter discounted as resulting in a mechanism so tiny as to be
too difficult to readily adjust and test manually during an
interventional procedure. Introducing a slot with sliding cover in
the side of the valve body, however, allows a mechanism
sufficiently large for practical use and can be added at reasonable
expense. For precise and quickly reproducible adjustment, the
sliding cover is positioned by means of a knurled turns ratio knob
fitted with a vernier scale, the exact arrangement thereof
contingent upon that of the air pistol modified.
[4243] XIII2c. Control of Propulsive Force (Exit Velocity) by Means
of a Calibrated Slide Cover Over a Slit Cut Into the Valve Body
[4244] In modifying an airgun, the internal structure of the valve
body remains unaffected, the addition of an external control being
less complicated and more readily accomplished. That the
modification is least variable from one model airgun to the next is
a significant factor in reducing errors. As seen in FIG. 47, fine
slot 227 covering an area to deplete the pressure delivered from
the valve body 228 to a value below that required to produce the
miniball impact force desired, such as 2 millimeters in width and
1.5 centimeters in length, is cut longitudinally into the valve
body toward its front end. The dimensions of slot 227 depend upon
the pressure in the valve body, so that, for example, fine slot 227
in a Crosman 1077 based modification would be larger than that in a
Daisy 622X.
[4245] The 12 gram cylinders in standardized use with commerically
available miniball airguns deliver CO.sub.2 at a pressure of 837
psi at 70 degrees Fahrenheit; however, the exact dimensions of the
slot depend upon the volume of valve body 228 or its adjustment by
the maker, which varies from one model airgun to the next. In an
airgun with a reciprocating slide, valve body 228 is integral with
the CO.sub.2 cylinder beneath it in the clip, pushing ledge 229
must consist of a lever that is disengagable or foldable to allow
the magazine clip to be removed from the grip for reloading, or a
pin must be placed through a slot and into a depression in the
slide. A slide frame or slideway in which the slide will be
contained and longitudinally slid to continuously open and close
the slot in a manner similar to some flat sliding door bolts is, in
a retrofit as opposed to an original design, applied to the outer
surface of the valve body.
[4246] The slideway is produced by die cutting and mold pressing
thin stainless steel sheet to the curvature of the valve body. The
sides or wings of the slideway extend outward enough to include a
calibration in the pressing. A die-cut rectangular slide or tang is
pressed to flush conform to the curvature of the valve body side
wall and the slide frame. The slide includes a calibration mark and
a hole in which to insert and fasten a small control handle, the
extension of the handle on the underside acting as a stop. To
minimize sticking resistance, the slideway and slide or tang may be
given a thin coating of polytetrafluoroethylene; however, the
closeness of fit of the slideway and slide must be such that
resistance to being slid must never allow the sudden jolt of
discharge to displace the slide.
[4247] The slide is positioned over the slot and covered over by
the slideway, which is then fastened to the valve body by blind or
pop rivets of 1.0-20 millimeters in flange outer diameter, in any
of several types manufactured by Textron Fastening Systems, Emhart
Division of Black and Decker, and other manufacturers, or threaded
inserts made by Emhart. The slide is now retained within the slide
frame against the outer surface of the valve body so as to freely
slide forward and backward over the slot. Retracting the slide
uncovers the slot from a fully closed hermetically sealed position
to a continuously variable open position that allows CO.sub.2 to
bleed out of the valve body reducing the propulsive force driving
the miniball through the barrel. In arteries, the direction of
blood flow as antegrade or retrograde is propotionally negligible
enough to disregard as a determinant of miniball impact or striking
momentum.
[4248] The use of engaging depressions or dimples in the slideway
and protuberances in the slide to act as detents at the calibration
marks is discounted as suggesting that these settings have a
favorable status. The height of the slideway above the outside of
the valve body is such as not to come into contact with the gun
body. In an airgun such as the Gamo V3 with a reciprocating slide
on the receiver, a slot can be cut in the side of the airgun body
slide to clear a handle of the pressure adjusting slide. However,
as a handle would have to be removed or folded to withdraw the clip
from the grip, a depression close to its leading edge or slot
closing end can be made to allow a pin to be inserted as a
removable handle to adjust the slide by aligning the calibration on
it to that alongside the slideway and to act as a stop.
[4249] To introduce a minitature electric motor inside the valve
body to move the slide that is powered by a battery and control at
the butt of the grip is discounted as inconsistent with the object
of providing a simple limited purpose retrofit at relatively low
cost. The modified airgun is sold with a table relating the
calibration to the exit velocity and indicating the range of
settings suitable for the tissue to be treated in a patient of
given species and size, and providing instructions for measuring
and finding the best impact force to use. A printed table that sets
forth the settings for a given tissue affected by specific disease
is consulted and the airgun adjusted to this setting. The end
position of the first implant is carefully observed
fluoroscopically and if in a vessel, angioscopically, to confirm
the setting and to apply any adjustment needed before proceeding to
the next discharge.
[4250] In use, the table is consulted for the recommended exit
velocity and impact force data for the barrel-assembly and
miniballs to be used for the tissue to be treated, the airgun is
test discharged against impact force registration paper (pressure
sensitive paper, tactile pressure indicating sensor film, pressure
sensitive film, Fuji Paper or Fuji Prescale) or Pressurex.RTM.
produced by Sensor Products, Incorporated, Madison, N.J., which is
a film of Mylar.RTM., E.I. du Pont de Nemours and Company, for
biaxially oriented polyethylene terephthalate (boPET) polyester
film treated to provide a certain color indicative of the
"pressure"(impact force). For higher resolution, a ballistic
pendulum is used to measure the impact force. Then the exit
velocity is adjusted by means of the slot slide introduced into the
valve body, and the airgun output measured again.
[4251] This process is repeated until the impact force has been
optimized for the tissue within the predictable limits. To expedite
adjustment in use, preliminary testing must also plot the relation
between the slide adjustment and the impact force. The effect of
the initial discharge is carefully examined before proceeding and
the exit velocity adjusted accordingly. Such viewability also
allows confirming the precise alignment of the barrel-assembly with
the configuration of the miniballs in the rotary magazine clip.
Airguns in current production that use rotary magazine clips do not
have a slide that reciprocates forward and backward along the top
of the receiver making it possible to retrofit the chamber with a
roof made of a suitable transparent polymer such as
polycarbonate.
[4252] The simplest airgun for use with a simple pipe
barrel-assembly must be be equipped with a potentiometer having a
control knob where the thumb contacts the grip or alternatively, a
three-way toggle switch with settings for recovery magnet off,
retrieve (a dropped miniball), and retract (a mispositioned
miniball). to adjust the magnetic field strength of either
trap-extraction tractive electromagnet in the most distal portion
of the muzzle-head from zero to the maximum. For use with a
barrel-assembly with a motorized turret to rotate the muzzle-head,
a bidirectional rotation control is also required in this location.
A critical increase in versatility is provided in commercially
available hand airguns suitable for modification that provide
semiautomatic operation by means of a rotary magazine clip or wheel
clip rather than a single ball advancing spring-loaded feed
line.
[4253] With a rotary magazine clip, multiple miniballs can be
positioned in front of the barrel-tubes at a single time. Rotary
magazine clips are intended for projecting pellets rather than
balls but can of For projecting plural miniballs simultaneously, or
multishot semiautomatic operation, the use of a rotary magazine
clip is preferred. A representative example of such a hand airgun
is made by Maruzen Kabushiki Kaisha to the specifications of and
sold in the United States by the Daisy Outdoor Products Company
under the trade name Powerline 622X. This model is designed to
shoot 0.220 inch (5.5 millimeter) pellets.
[4254] The rotary magazine clips provided with this airgun are
designed to hold pellets rather than miniballs, but as is
demonstrated by Daisy model 617X requires only the addition of a
slight midcircumferential ridge along the internal surface of the
hole to achieve retention of a miniball rather than a pellet.
Interchangeable the rotary magazine clip mechanism is the more
versatile, allowing one to four miniballs to be poised for
discharge at a time. If a rotary magazine clip that is conventional
in diameter but adapted to hold millimeter miniballs will not allow
the number of discharges required for a procedure, then the rotary
magazine clip must be replaced during the procedure, an automatic
mechanism to remove and replace the rotary magazine clip exceeding
the present scope.
[4255] XIII2d. Docking Stations for Modified Commercial Airguns
[4256] Airguns can be prepared for interventional use by
modification of commercial airguns. For applications requiring
miniball precise placement, a `docking station` that includes a
linear positioning stage for automated incremental transluminal
movement is provided. However, the limitations in control over
discharge velocity limit the application of modified airguns to
applications in the airway and larger ductus. A modified air pistol
is suitable for use with a simple pipe in veterinary practice to
alleviate tracheal collapse.
[4257] XIII2e. Positioning Modes of Operation
[4258] Positioning and operation of the muzzle-head at any given
time may be manual, manual with direct control over the linear
positioning table airgun mounting and/or turret-motor, or manual in
initiating automatic sequences or discharge groups wherein once
selected by the operator, the rotary angles and/or distance
separating the individual discharges is accomplished automatically.
During manual, as opposed to automatic transluminal movement, the
turret-motor and discharge remain disabled. The controls onboard an
ablation or ablation and angioplasty-capable barrel-assembly allow
the operator to switch the automatic retraction of extended
tool-inserts with trap-filter deployed on or off as desired.
[4259] The urgency to minimize ischemia while achieving a closely
positioned formation of miniball implants may recommend the
concurrent use of the turret-motor during discharge synchronized to
the transluminal movement of the barrel-assembly by the linear
positioning stage. The control over transluminal movement by a
clocked linear stage allows the exposure time to atherectomizing
action of a laser or rotational burr to be tightly governed. Timed
discharge is controlled as an auxiliary function of the positional
system controller.
[4260] XIII2e(1). Positioning with a Simple Pipe
[4261] Because the structured anatomy demands the discretionary
placement of each implant, use of a simple pipe in the airway is
always under direct manual and never automatic control. The airway
in all but the tiniest (veterinary or premature birth) patients
affords sufficient space to maneuver the handpiece, the structures
involved are observable endoscopically, ultrasonographically, or
fluroscopically. The tractive electromagnet is hand-operated.
Airgun (not positional) operation in this or similar environment is
semiautomatic as not to require reloading mid-magazine clip.
[4262] Other than not having to reload the airgun between clips and
energization of the tractive electromagnet, the simple pipe lacks
the auxilliary functions required in a radial discharge embodiment
suitable for use in the bloodstream which demands very fine and
fail-safe retraction or deployment during transluminal movement
near or over a lesion, which accordingly, is automated. Control of
the tractive electromagnet, and the transluminal advancement,
withdrawal, and rotation of the simple pipe are thus completely
manual.
[4263] XIII2e(2). Automated Positioning with a Radial Discharge
Barrel-Assembly
[4264] Most extraluminal stenting will, however, pertain to ductus
no larger in lumen diameter than 3 millimeters, and except for the
segments that necessitate treatment, have a relatively uniform
structure. Discharge in smaller ductus seldom involves individual
longitudinally disparate shots but rather the unform incremental
implant-carpeting of a lesion or the entire lumen. In this
environment, safety measures to avert downstream embolization by
escaped miniballs or plaque debris are actuated automatically even
when longitudinal or rotary movement of the barrel-assembly is
manual. When longitudinal or rotatory increments no greater than 2
millimeters are required, control over transluminal displacement,
the rotary angle of the muzzle-head and thus the direction of the
muzzle-ports, recovery tractive electromagnets, and radial
projection units demand measured control of machine accuracy.
[4265] For this reason, manual control as it pertains to the
vascular system, for example, is substantially limited to
discretionary direction over gross transluminal distances such as
from the introducer sheath to the lesioned segment and back,
angular displacement when noncritical, and the larger transluminal
distances separating lesions. Manual control is otherwise pertinent
to operator commanded automated actions, to include the distance
separating successive discharges to apply across a given lesion and
optionally, the number of individual discharges to constitute the
discharge sequence or group. The airgun is provided with controls
for the operator to direct discharge in groups or discrete
sequences where each such group comprises a selected number and
uniform spacing of individual discharges.
[4266] The duration of the manually controlled automatically
unfolded operations is usually brief, the length of the ductus to
be treated limited to the segments that are diseased or to be
stented. Control of the airgun in executing these automatic
discharge sequences is accomplished by switching relay and time
delay components extrinsic to the airgun mechanism proper and is
unrelated to the fully automatic operation of firearms. While the
operator selects the number and distances to separate the
discharges (individual shot or shot-groups) in a set, the
coordinated timing of discharge and action of the linear
positioning table stepper (or hybrid stepper) motor in
incrementally moving the barrel-assembly and, if applicable, the
turret-motor in angling the muzzle-head in each discharge group, is
electronically coordinated.
[4267] In addition to positional adjustments of the muzzle-head
that exceed the manual capability to directly manipulate or the
imaging capability to clearly see, safety factors relating to the
prevention of inappropriate discharge and the actuation of
auxilliary functions, such as the deployment and retraction of
side-sweepers and trap filter, disablement of the trigger-switch,
inactivation of the linear positioning table stepper motor and
radial projection units, if present, during discharge, are not left
to operator memory. However, not all functions are preferably
automated, those configurational with respect to the apparatus
applied preprocedurally for reasons of simplicity and economy.
[4268] Thus, as described above, the number of muzzle-ports and any
eccentricity in the trajectories to characterize each discharge are
achieved by preselecting a barrel-assembly of suitable
configuration, while the number, caliber, and type of implants is
prearranged by the choice of clips, the miniballs and blanks in
each clip position, and the barrel-assembly used. While changes in
the exit velocity could be automated to execute during a discharge
set pattern, such adjustment is seldom required from one lesion to
the next or even during a procedure, and to impart this function
increases the cost of the airgun. Accordingly, if necessary, the
exit velocity is adjusted once a short term automatic routine has
terminated. A malfunction mid-routine abends the routine and
disables the airgun. Immediately upon completion of the routine,
the trigger switch is reenabled.
[4269] Thus, once the apparatus has been preconfigured for the
specific procedure, manual control of a radial discharge
barrel-assembly consists of gross transluminal movements to bring
the muzzle-head within or away from close reach of the site to be
treated, selecting the exit velocity, the number, and the distance
of uniform increments to separate the automatically positioned and
timed successive discharges applied to a given lesion, the
deployment of radial projection units if present, direct remote
manual control over the transluminal position of the muzzle-head
and rotational angle of the muzzle-head when not radially
symmetrical, and the electromagnet settings. For reasons of safety,
the energization of the electromagnets at the resting trap-recovery
field strength during discharge and the deployment of the trap
filter at the same time as the radial projection units when tissue
removing tool-inserts have been installed are, however, not left to
memory but made automatic.
[4270] XIII3. Dedicated Interventional Airguns
[4271] XIII3a. Operational Requirements
[4272] Airguns dedicated for interventional use must respond to
operative and human factors design desiderata, to include
expeditious and immediate control under operative conditions,
consistent performance without deviation from the control settings,
and ergonomics, or optimization and comfort in manipulability.
Properly configured, an interventional airgun reduces operative
times by providing multiple points for quickly adjusting the exit
velocity or impact force between successive discharges, the
recovery electromagnet field strength to retrieve a mispositioned
or loose miniball, and usually provides duplicate control panels to
allow control by an assistant when circumstances take the attention
of the operator from discharge parameters as such. Dedicated
interventional airguns include control points in addition to a
slidably adjustable slot as pressure relief valve in the valve
body.
[4273] Due to the variability in mechanical properties of diseased
tissue, unless the operator is confident of consistency from one
target point to the next, adjustment in exit velocity should be
based upon testing the target tissue as described below in section
XVII entitled Testing and Tests below as pertain to internal
approach. A single standard 12 gram disposable liquified CO2
cylinder, usually referred to as a powerlet or pistolet, will
suffice for most procedures. When inadequate, the cylinder is
replaced before the depletion of pressure affects power output and
performance, which factor is paramount and will vary with the
specific embodiment. The need to replace a cylinder is reduced
about twenty-fold and usually eliminated through use of an 88 gram
cylinder, sold under the trade name Crosman AirSource.RTM.) or the
equivalent, and may be sold in England as relabeled with the brand
name SMK.
[4274] Shown in FIGS. 81 and 82 are interventional airguns with
gravity-fed queue, or sequential-feed miniball loading, hence,
capable of discharging but a single miniball at a time. With such a
gravity or spring advanced clip queue, a small rocker lever arm of
the same kind as is used in conventional air pistols is used to
admit only one miniball at a time for discharge. These airguns are
suitable for use with simple pipe-type or radial discharge single
or monobarrel barrel-assemblies. The type of miniballs used is
changed by removing the hopper, shute, silo, or clip containing one
type of miniball and replacing it with one containing another type
of miniball. Feed that allows miniballs to be queued allows varying
the successive type miniballs of the same diameter in the queue.
Monobarrel radial discharge barrel-assemblies lack means for
pressure equalization, making these unsuitable for use in the
bloodstream.
[4275] Unlike the fully capable embodiment described below, simple
pipes are for manual use and are not used in conjunction with a
positional control system. When connected to a basic interventional
airgun rather than a modified air pistol, the simple pipe is still
discharged as with more advanced airguns by depressing a plunger or
dead-man trigger switch. Simple pipes and airguns are suitable for
use in veterinary practice to repair a collapsed trachea, and may
be used to administer subcutaneous drug miniballs in humans. A
simple pipe inserted in a modified air pistol or a simpler
dedicated interventional airgun is primarily intended for use in
the airway or in any ductus for which the distancing between
successive implant discharges does not demand a level of precision
beyond that attainable by hand.
[4276] Airguns for supporting monobarrels whether simple pipes or
radial discharge barrel-assemblies can be either gravity fed as
shown in FIGS. 81 and 82, a rocker arm (not shown) used to admit
one miniball into the chamber at a time, or rotary clip fed. Radial
discharge Barrel-assemblies which discharge two or more miniballs
per discharge use a rotary clip feed. Accordingly, the dedicated
interventional airguns shown in FIGS. 81 and 82, especially the
latter, might have been depicted with the rotay clip feed mechanism
as shown in FIGS. 31 and 32. Very small dogs, for example, are
however, treated with a monobarrel radial discharge
barrel-assembly, which surrounds the pipe as barrel-tube within a
protective shell, allows more than a single miniball to be
discharged at a time, and when discharged as an auxiliary function
of a positional controller, achieves precise incremental
placement.
[4277] Whether simple or advanced, dedicated interventional airguns
provide a toggle switch to energize the electromagnet, a
potentiometer control knob for adjusting the solenoid timing, and a
manually adjustable slide-cover in the valve body. With any
barrel-assembly, controls must be conveniently placed to allow
immediate adjustment in the recovery electromagnet field strength.
In a radial discharge barrel-assembly, two recovery electromagnets
are used, and each is separately controllable. Typically, the
controls for recovery electromagnets comprise a rocker switch
marked `Off` to one side and `On` to the other, and an adjacent
rotating knob activated only when the rocker switch is in the `On`
postion to continuously vary the field strength, the provision of
presets considered obvious.
[4278] The simplest interventional airgun is thus more versatile
and adept than is a modified air pistol Not pertinent to the use of
a simple pipe barrel-assembly are, for example, the need to accept
rotary magazine clips, which pertain to use with radial discharge
barrel-assemblies with two or more barrels (barrel-tubes), to
accommodate much less provide controls for a linear positioning
stage or table, as well as oxther components such as a
turret-motor, required in radial discharge barrel-assemblies for
use in small vessels and ducts. FIGS. 31 and 32 show the use of a
rotary magazine clip which can index one or more miniballs into
position for discharge at a time. Such a feed is usable with a
simple pipe barrel-assembly, which has but a single barrel-tube,
when one miniball is loaded in each hole in the clip. Loading more
than one miniball per hole is pertinent only to radial discharge
barrel-assemblies.
[4279] Even though simple pipes and radial discharge
barrel-assemblies with one barrel-tube are both monobarrels, an
airgun for use with the latter requires controls for positional
control when used. As described above, modified air pistols provide
fewer points of control than do dedicated inerventional airguns. To
incorporate multiple controls in an air pistol and provide a stable
mount for attachment to a linear stage is discounted as defeating
the lower selling price that is its primary object. Manual
positioning necessitates some freedom of movement, and as with a
modified air pistol, this is attained by providing adjustability in
the exit velocity to compensate for some bending in the
barrel-assembly. Such presumes that the operator has fully tested
the exit velocity or impact force at various levels of sag prior to
operating. Dedicated interventional airguns incorporate the same
valve-body slideway as modified airguns as the basic means of
control, but to expedite and refine adjustments, offer additional
control points.
[4280] XIII3b. Interventional Airgun with Liquid
Vaporization-Upon-Release Cartridge or Compressed Gas Cylinder
Connected Directly to the Valve Body Inlet Suitable for Use Over a
Range of Exit Velocities (Forces of Penetration) in Quick
Succession with Moderate Redundancy as to Points of Control Over
Discharge
[4281] Gradual curves in the barrel-assembly reduce the exit
velocity and sharper curves can do so to a significant extent by
percent in relation to the range of exit velocities effective in
placing the miniballs subadventitially before puncturing the outer
fibrous layer of the ductus. The use of thicker tubing in the
barrel-catheter and barrel-tubes, a larger diameter
barrel-catheter, use of centering devices to place the barrel-tubes
farther from the central axis, and blood-tunnels to increase the
stiffness of the barrel-catheter over the length usually not
required inside the body have been mentioned above. A description
of an interventional airgun that incorporates automatic positional
control will be found following a description of components such as
a linear positioning table used to execute the positioning. The
incorporation of a photo-ablation excimer laser also adds stiffness
to the barrel-assembly.
[4282] A radius of curvature that is severe without kinking or
distorting the barrel-tube in internal diameter demands greater
propulsive force to achieve the same exit velocity as were the
barrel straight. Operative speed being a crucial factor in
achieving a good result, to expedite adjustment of the apparatus to
achieve the exact exit velocity desired, provided are
interventional airguns with several control points, some redundant.
Interventional airguns are always to be provided with guidelines
for selecting and testing exit velocity for a specific application.
Due to the greater variability in mechanical properties of tissue
once diseased, the automated coordination of the separate controls
of dedicated interventional airguns to instantly bring the gun to
preset exit velocities must afford fine adjustment if not
continuous variability. Such control would not be particularly
advantageous, and is not considered to be worth the additional
expense.
[4283] In a simple embodiment intended for use with a refillable
cylinder of compressed air that has been pressurized for use with a
tissue of certain properties as shown in FIG. 81, an
electropneumatic valve consisting of a plunger solenoid actuator
and valve body is used to admit and within a small range compared
to a regulator, control the pressure of the gas used to propel the
shots, hence the exit velocity and force of impact. The control
knob adjusts the voltages that regulate the extent and duration
that the electropneumatic valve opens to the pressurized gas.
Providing dedicated interventional airguns with an additional foot
control switch to trigger discharge is not preferred. A
conventional electrical foot-switch must be adapted to incorporate
a safety pin that must be released by depressing a lever with the
toe of the opposite foot, and limited to triggering only, the foot
switch is too limited.
[4284] The incorporation into a foot operated control panel of all
the controls necessary to use the apparatus is rejected as inviting
unintended actuation. FIG. 81 is a block diagram, not to
proportion, of a gas-operated surgical miniball implant insertion
airgun with compressed gas cylinder connected directly to the valve
body inlet. While represented this and the dedicatied
interventional airgun next to be described are represented as
gravity fed as suited to use with a simple pipe barrel-assembly, it
is to be understood that either can also use rotary magazine clips
and so accommodate any kind of barrel-assembly. In addition to the
valve controls provided, different delivery tubes friction fit to
the end of the barrel can be used to variously reduce the barrel
exit velocity, hence, the force of impact.
[4285] Such an embodiment, using a single cylinder of compressed
gas without the additional expense of a regulator, is suitable for
use where the a range of exit velocities or forces of penetration
is required, as when treating a single tissue to a single depth.
Under normal circumstances, a disposable delivery catheter designed
for the particular application is provided. A device as shown above
and in the following FIG. 82 allows continuous variability in the
force impact, which expedites testing tissues for the purpose of
disposable catheter design. The compressed gas can be supplied, for
example, from either an internal prefilled disposable CO.sub.2 or
by means of piping from an external CA compressed air cylinder.
Whereas CO.sub.2 delivers 837 psi at 70 degrees fahrenheit, a
compressed air cylinder can be filled to a preferred pressure.
[4286] With the interposition of a small adaptor, either a CO.sub.2
or CA cylinder can be connected to the valve body inlet. Using a
single source of compressed gas without regulator keeps the design
simple and economical. A small CO.sub.2 cylinder inserted within
the enclosure makes the single-purpose airgun self-contained and
compact. Containing nonliquified gas, a compressed air cylinder is
larger and therefore connected from outside through a hose but can
be filled to any pressure within its design specification. With or
without a regulator, control with a single source of compressed gas
is limited to reduction in the outlet pressure (also referred to as
a canister or tank). With this basic design, variability in shot
impact force is limited to adjustment in the field strength and
duration of plunger solenoid actuation.
[4287] Preserving this simplicity and economy limits the
pressure-reducing features that can be built into the airgun.
Nevertheless, by connecting compressed air cylinders filled to
different pressures, even the simple airgun can be used to treat
different tissues to different depths of penetration. In such use,
multiple cylinders of compressed air are connected and switched
among manually by means of a pneumatic or electronically by means
of an electopneumatic station valve. This can be done at no great
expense when switching is manual; however, the parts necessary to
switch among different cylinders with electronic valves loses the
economic edge over a design that affords continuous variability in
pressure through the use of a regulator. A warming jacket
containing a heating element or coil about the gas delivery tube
with thermostat or pyrometer control can be used to change the
temperature and so adjust the pressure.
[4288] Since conventional CO.sub.2 cylinders are rated for up to
1800 pounds per square inch (psi), the range of pressure control
gained in this manner is much less than it is with compressed gas
cylinders, which can withstand thousands of psi. For clarity, FIGS.
81 and 82 show the pressure gauge P, temperature gauge or pyrometer
T, and voltmeter V housed separately from the table-top or
stanchion-mounted main unit. PSOS is a full-wave rectified
regulated power supply output switch. The take-offs for the
different components are voltage divided by a bleeder resistor,
each circuit controlled by a variable resistor. EPOT is a
electronic potentiometer remotely operated from the remote hand
control. In a simpler version, the potentiometer is mechanical, in
the same position in the circuit, but mounted on the chassis rather
than the hand control, and VCTDR is a voltage-controlled time-delay
relay.
[4289] Essentially, there are two circuits, one pneumatic, the
other valving the passage of gas through the pneumatic circuit. The
combination of the plunger solenoid and the gas valve constitute a
special purpose impulse-actuated electropneumatic valve. Whereas a
enclosure-mounted manually operated potentiometer is less costly
and assumes operation by an assistant, an electronic potentiometer
in the remote hand control affords the operator direct control;
both can be connected in series. Depressing the remote control
`dead-man` or plunger type trigger switch at the top of the
joystick control connects the power supply through the EPOT and
VCTDR to the undamped direct current powered plunger solenoid,
energizing the solenoid coil. This causes the solenoid plunger
(slug, armature) to strike or punch the spring-loaded valve inlet
pin forcing open the valve within the valve body for the interval
set by the VCTDR.
[4290] Use of the plunger switch trigger requires release of the
safety by retracting a pin intromitted into the side of the control
button or key which is placed at one end of a spring-loaded lever
retracted by pressing the opposite end with the ball of the index
finger. The gas thus admitted to the rear of the mini ball implant
in the receiver propels the implant as a projectile through the
barrel and delivery tube at the target tissue. Adjustment in the
output of the power supply through the potentiometer varies the
actuation field strength of the solenoid, varying the punching
force of the solenoid plunger against the valve pin. Increasing the
force of plunger impact upon the valve pin also slightly increases
pin excursion, hence, valve open-time. Valve open-time is thus
determined both by the interval that the switch connects the
solenoid to the power supply and by the voltage. This timing may be
controlled as a structural or mechanical feature of the switch
contacts or through a separate electronic time-delay relay.
[4291] Absent such a solenoid actuation time mechanism, the
solenoid plunger would not retract until the switch was released,
which interval is too long. The discontinuous character of the
function, which involves the intermittent discharge of sudden
shots, does not lend itself to servomechanical control; instead, a
V voltmeter indicating EPOT output on the enclosure serves to
implement human feedback. The acrylonitrile butadiene styrene (ABS)
enclosure with a thermal conductivity between 0.14 and 0.21 W/mK
and 97 cubic feet per minute (cfni) fan with plastic vanes and
frame prevent the undesired buildup of heat that could materially
alter the gas pressure and therefore terminal ballistics. Adjusting
the fan speed and thus the volume of air moved through the
enclosure by means of a thermostat is another way that the
temperature of the gas can be conrolled to obtain variability in
pressure.
[4292] Conventional means exist for preventing the temperature to
exceed a set limit, and even were such to malfunction, all
compressed gas cylinders incorporate a pressure relief mechanism.
Thus, even using a single cylinder, and even when the cylinder
contains CO.sub.2, which is not normally viewed as affording
variabiity in pressure, numerous variables are available to control
the pressure and therefore the force of impact and depth to which
the shot will penetrate given tissue. Of these, the least costly
embodiment shown here employs those variables that govern valve
open time. In an embodiment that must afford a wide range of
penetration forces for a single procedure, a regulator capable of
continuously adjusting the gas pressure is used. Whereas a
regulator and the control means shown allow pressures less than
that to which the cylinder is pressurized, increasing the
temperature allows the cylinder pressure to be exceeded.
[4293] The power controlled from the remote control hand piece is
represented as controlling both the output from the power supply
through the electronic potentiometer and the input power
proportional time delay. That is, the same potentiometer is used to
vary the input to the solenoid and the time-delay relay to
continuously vary the force and interval that the valve is held
open, both of which factors increase valve open-time. Separate
control of the time delay does not significantly extend control
variability. Whether manually adjusted in a simpler model or
electronically in one more costly, a regulator is usually
controlled separately. In such an embodiment, the regulator is in
effect the gross adjustment, whereas the controls shown here serve
for fine adjustment. To avert disruption due to malfunction, more
than one such relatively simple apparatus, each adjusted to the
same settings, should be present. If more than two are available,
differently adjusting these in pairs allows treating different
tissues.
[4294] XIII3c. Interventional Airgun Suitable for Procedures
Involving the Treatment of Different Tissues to Different Depths in
Quick Succession with Redundant Points of Control to Adjust the
Exit Velocity
[4295] FIG. 82 is a block diagram, not to proportion, of a
gas-operated interventional airgun suitable for procedures
involving tissues that differ widely in resistance to penetration
where there is the need to penetrate to different depths,
necessitating adjustability over a wide range of shot impact
forces. The airgun is shown with a gravity queue-fed magazine
implying use with a simple pipe, but is capable of loading rotary
magazine clips. The use of an interventional airgun that lacks
automatic positional control where precise distancing between
successive discharges is essential, as is often true in the
vascular tree, for example, is not preferred. Such an airgun is
suitable for use, for example, with a simple pipe-type
barrel-assembly in the airway or in any ductus operable manually as
not to demand precise distancing between successive implant
discharges.
[4296] While shown in FIGS. 81 and 82 as gravity loaded, such
airguns can be loaded with rotary magazine clips that allow
multiple miniballs, usually two, aimed diametrically, to be
discharged at a time. As previously described, such clips allow the
mixing and matching of different type miniballs, some of which may
consist entirely of medication or any of numerous other type
substances. The barrel-assembly can, for example, be used to
introduce miniballs that consist entirely of medication or
irradiating seeds, which may constitute the entire purpose of the
procedure, or such may be done on an initial pass, an interval
allowed to pass for the preparatory medication to take effect, then
the barrel-assembly reversed in direction to infix the implants.
That is, reloading at the proximal extracorporeal end of the
apparatus eliminates the need to withdraw and reintroduce the
barrel-assembly.
[4297] Interchangable single, or individual `BB,` and multiple-shot
or shotgun shell-adapted pellet casing loading mechanisms allow the
same propulsion apparatus to be used analogously to a rifle or
shotgun, where the object is likewise similar--either to deliver
individual shots with discretionary placement in suture mode or
distribute shots over an area in stent mode. The latter is far more
frequent, uniform distribution spreading the magnetic attraction
and therewith any risk of pull-through, and with the need for
precision reduced. For improved visibility, the large digital
pressure gauge P, temperature gauge or pyrometer T, and voltmeter V
are housed separately from the table-top or stanchion-mounted main
unit.
[4298] The following acronyms are used. PSOS--power supply output
switch. EPOT--electronic potentiometer remotely operated from the
remote hand control. In a simpler version, the potentiometer is
mechanical, in the same position in the circuit, but mounted on the
chassis rather than the hand control. VCTDR--voltage-controlled
time-delay relay. EPR--remotely controlled electropneumatic
regulator; as with the potentiometer, using a manual regulator with
control knob mounted on the enclosure considerably reduces the cost
of the apparatus. Whereas manual control makes maximum use of an
assistant, remote control allows immediate adjustment by the
operator. The compressed gas is stored in a disposable CO.sub.2
cylinder prepressurized and unrefillable at 837 psi at 70 degrees
Fahrenheit.
[4299] CO.sub.2 cylinders are available in a variety of sizes, to
include 9, 12, and 88 grams or 9, 12, or 20 ounces. The cylinder is
connected to the valve body through a continuously variable
regulator that allows a range of gas pressures for use with any
suitable tissue. A manual regulator can be used for economy but an
electrically controlled regulator allows direct control by the
operator. The use of a regulator eliminates the need to connect
differently pressurized cylinders or change the temperature
whenever treatment moves from one tissue to another. A time-delay
relay is still required to limit the interval that the solenoid is
actuated, but a potentiometer, while still desirable, is not
essential for control.
[4300] While less costly, a manual system that interswitches among
plural cylinders does not achieve equivalent continuity or
smoothness of operation. To employ an electrical means of switching
among cylinders would lose much of the economic advantage of
switching compared to a manual if not an electrical regulator. A
manually operated regulator can be controlled by means of a knob on
the enclosure. To avert disruption due to malfunction, more than
one apparatus should be present and adjusted to the same settings
as the procedure unfolds. With a regulator, other means for
altering the force of impact, as by changing the delivery tube to
one of different length or a material of different coefficient of
friction are unnecessary.
[4301] XIII3d. Interventional Airgun with Multiple Exit Velocity
Control Points for Quick Midprocedural Adjustment, Using Rotary
Magazine Clips, and with an Automatic Positional Control System
Suitable for Implanting the Wall of a Blood Vessel
[4302] An interventional airgun suitable for use in the vascular
tree incorporates automatic positional control that allows
successive discharges to be placed at smaller distances than can be
attained manually with accuracy. To achieve uniformly equidistant
separation of the implants in a formation and thus reduce the risk
of pull-through within a ductus having a caliber the size of the
average artery, for example, necessitates automatic operation, the
muzzle-head as `tool` advancing or rotating, discharging, and
continuing according to the control input of the operator. Such an
airgun is the same as that last described but supplemented with
positional drives and controls and a rotary magazine clip that
unlike the queue or linear succession spring-loaded clips in many
commercial hand air pistols if not that type described above as
more capable, and gravity-fed loading in the preceding
interventional embodiments, which are meant for use with a simple
pipe-type barrel-assembly, can load multiple miniballs in any
combination for simultaneous discharge.
[4303] Since the second of the two kinds of modified commercial air
pistols described above uses a rotary magazine clip, it is capable
of discharging more than a single miniball at a time; however,
lacking a positional control system, the targeting of each
discharge must be achieved manually, which taking time, is unsuited
to use in the circulatory system and in the coronary arteries in
particular, where quickness is imperative for averting the ischemia
that can induce a myocardial infarction. The same may be said of
use in the carotid arteries where the risk of a cerebral infarction
must be minimized. Of the two types of interventional airgun
described above, neither uses a rotary magazine clip as allows the
use of more than a single barrel-tube. In the second and more
capable air pistol, the rotary magazine clip is rotated by a pawl
that is mechanically linked to the trigger and engages notches
about the circumference of the magazine.
[4304] In the mechanical system seen in a conventional airgun that
uses a rotary magazine clip, the pawl that rotates the clip is
moved when the trigger is pulled back, so that the rotary magazine
clip has already rotated or indexed to place the next load before
the CO.sub.2 inlet when the trigger reaches the end of its travel
(excursion, throw), at which point the hammer is released to strike
the valve body pin effecting discharge. Here, the same sequence is
reproduced through the use of a plunger switch that when partially
depressed completes the circuit through a small electromagnet, and
when fully depressed, completes the circuit through the push or
punching solenoid used as a hammer.
[4305] When triggering is electrical, the rotary magazine clip and
pawl are no different than those used in a mechanical linkage to
the trigger but differ in that the pawl is actuated by the small
electromagnet that is energized by depressing the spring returned
trigger consisting of a raised plunger (pushbutton, dead-man)
double pole double throw normally open momentary close contact
switch mounted within the top of the joystick. One point of control
in this airgun governs valve body pin depression time. While this
interval could be affected at the trigger switch, more precise and
replicable control is achieved by the means to be specified.
[4306] XIII3e. Linear Positioning Stage or Table Airgun Mount
[4307] The airgun linear positioning table (linear platform, linear
stage) mounting is purchased as a complete subassembly, to include
both the linear positioning table and actuator. Numerous types of
linear positioning tables are available, some open-loop controlled
with stepper motors, others closed-loop controlled with dc
servomotors. The actuator can be linear or rotary, and in either
category, any of several different kinds. The table itself requires
no modification; rather, adaptation for the present purpose
consists of its positional control programming. A linear
positioning table is no less useful for precisely positioning a
radial projection system injection tool-insert, for example,
whether the injector is an electrical/fluid system-neutral or
spring discharged syringe in the muzzle-head of the barrel-assembly
or a fluid injector in a separate radial projection catheter.
[4308] The Parker Hannifin MX80S miniature linear motor stage with
stepper motor under open-loop point-to-point control used with a
Compumotor.RTM. 6K controller represents one suitable linear stage.
The operator brings the muzzle-port or ports to the starting
position for the programmed discharge pattern and sets the
point-to-point distance (interval) to separate the successive
equidistant discharges and the overall length (segment, stretch) of
the duct or vessel to be implanted. Such is translated as
increments to separate the starting and ending positions of the
linear stage. The operator then uses a joystick or cyclic-like
control arm as described below to initiate the execution of this
number and distance of moves forward or backward. Once the pattern
is confirmed to have been set correctly, the joystick is used to
indicate the direction, the safety is removed from the plunger
switch at the top of the joystick, and the plunger switch depressed
to execute the pattern that was set.
[4309] Control is addressed in the section below entitled Airgun
stenting (position and discharge) control panel. The patterns may
consist of discharges along a straight line or lines (advancing or
withdrawing), or straight lines followed by rotation and return
(reversal of direction), or the repetition of the latter after the
muzzle-head has been rotated to longitudinally (transluminally)
pass over unimplanted arcs. While the use of a muzzle-head having a
larger number of radially directed muzzle-ports so that all arcs
are implanted simultaneously is preferred, such rotation and
reversal allows the use of a barrel-head containing fewer
barrel-tubes, which may be larger in diameter and thus allow the
delivery of larger miniballs.
[4310] XIII3f. Positioning of the Barrel-Assembly with the Linear
Positioning Table and Turret-Motor
[4311] XIII3f(1). Type and Efficiency of Control
[4312] Turning now to FIGS. 83, 84,and 85, both the closed-loop
control of the turret-motor and open-loop control of the linear
stage are initiated by the operator with the joystick, forward to
move the table forward, backward to move it backward, and clockwise
or counterclockwise to move the turret motor to the corresponding
angle. Move and discharge operation is limited to the linear stage
or transluminal positioner. Transluminal runs consisting of
translation by the linear stage, holding fast while the timing
relay signals the airgun hammer direct current powered plunger
solenoid to operate, then executes the following increment, are
performed one at a time, direct observation and action cancellation
or override by the operator taking precedence over any automatic
function.
[4313] There is, therefore, no stack or register to store
successive transluminal discharge runs, and no provision for the
programming of successive runs is allowed. When it is desired to
induce oscillation in the translatory or transluminal axis, the
linear stage is controlled in a closed loop that may be
intentionally derivative gain overdriven or overamplified. Unless
made to progress at a very slow rate, continuous positional
control, whether by direct analogy whereby the muzzle-head would be
made to move say, one millimeter for each move at the control of a
centimeter, or by continuous directional incrementing, so that the
muzzle-head would continue to increment in the direction of the
control until the control was retracted, are both subject to
constant overshooting.
[4314] The form of control must not permit a condition such that
every change in position requires to be corrected, much less
several times. Wasted motion would soon fatigue, prompting
sloppiness where this must not be tolerated. While the first of
these forms of control is the most intuitive or consistent with
spontaneous eye-hand coordination, and the second is more intuitive
than control that is based upon strict adherence to a previous
setting of controls to specify the number, size, and direction of
the increments to be executed automatically, for interventional
application, where losses in efficiency based upon essential design
factors are unacceptable and impatience with constant overshooting
might induce carelessness, the first of these forms of control is
rejected and the second reserved for quickly positioning the
muzzle-head at the starting position for automatic discharge.
[4315] Once initiated, however, the system requires that the number
and size of the increments to comprise each movement be entered
first and the joystick or cyclic used to indicate the direction of
movement, the latter being singular in any one such discharge-run
or compound action. The apparatus then automatically switches
between the movers (turret-motor and linear stage) and the airgun
direct current powered plunger solenoid used to strike the valve
body pin, stopping long enough between increments to allow the
implants to travel to the trajectory termini. Shifting the joystick
forward moves the linear stage stepper motor distad, backward
proximad, tilting to the right or rotating clockwise moves the
turret-motor clockwise, and tilting to the left or rotating
counterclockwise moves the turret-motor counterclockwise.
[4316] The joystick has a central null position through which
changes from forward (distad) to backward (proximad) direction of
the airgun mounting linear positioning table must pass, so that
reversal cannot be immediate. Similarly, rotation of the
turret-motor cannot be reversed immediately, because a null region
separates clockwise from counterclockwise contact, and since
forward-backward excursion passes through the rotatory null region,
simultaneous actuation of the turret-motor and linear stage is
impossible. Actuating the automatic discharge (autodischarge)
rocker switch shown in FIG. 85 causes the time delay relay shown in
FIG. 84 to alternately switch between either the linear stage
stepper or turret-motor as mover to the airgun solenoid that when
energized strikes the valve-body pin releasing CO.sub.2 into the
airgun chamber causing the implants to be ejected.
[4317] The airgun is mounted on a linear positioning table that by
moving the airgun bodily, transluminally advances or retracts
(withdraws) the muzzle-head. The linear positioning table can be
used to a. Accurately reposition the muzzle-head once the
barrel-assembly has been inserted into the airgun barrel, which
involves only control over the linear stage and turret-motor as
movers, b. Reposition the muzzle-head and then effect discharge
semiautomatically, the operator manually triggering each discharge,
which alternates between positional control and discharge, or c.
Direct automatic repositioning and discharge, in which compound
action the muzzle-head is manually directed to reposition by
uniform distances (increments, stretches) stop at each conjunction
by a fixed time that is long enough for the airgun to discharge
with the longest barrel-assembly, and then discharge automatically
at each stop, which requires the automatic and coordinated control
of the movers and the airgun.
[4318] Turning now to the airgun control panel shown in FIG. 85,
once angioplasty has been completed, the barrel-assembly is
inserted into the airgun. The power supply is activated by pressing
the ON-OFF toggle switch to the `ON` button. To bring the
muzzle-head to the starting position for discharge, the joystick is
held in the direction required until the linear stage and the
turret-motor have incremented toward and positioned it thus.
Semiautomatic discharge is appropriate for isolated discharge, but
implantation for stenting demands a proximity and accuracy of
adjacent placement that only machine controlled automatic discharge
allows to be attained. Once the starting position has been reached,
the airgun can be a. Discharged manually or semiautomatically by
releasing the safety on the dead-man trigger switch and depressing
the trigger, or b. Semiautomatic discharge initiated by using the
upper dial to set the number of increments and the lower dial to
set the length in millimeters of each increment.
[4319] The automatic discharge rocker switch is then shifted to the
on position, and the direction of automatically executed discharge
is commanded by shifting the joystick for the equivalent or
analogous intraluminal movement, meaning forward for transluminal
advancement, backward for retraction, rotated clockwise for
clockwise rotation of the turret-motor, or rotated counterclockwise
for counterclockwise rotation of the turret-motor. Since the
preparatory angioplasty is generally carried out manually with the
barrel-assembly independent of the airgun, automated positioning
with the table ordinarily commences with insertion into the airgun
barrel of the barrel-assembly for the purpose of placing the
intraductal stent implants. So long as the barrel-assembly is used
independently of the airgun for angioplasty, the turret-motor is
seldom if ever used as a mover but rather as a means for generating
heat for thermal angioplasty.
[4320] When the barrel-assembly resists rotation manually, then
depending upon whether connection of the control electronics to the
barrel-assembly is at the end-plate or in front of the airgun
muzzle, the free proximal end of the barrel-assembly can be
temporarily inserted into the airgun to connect the turret-motor.
The uniform increments, each a sum of component point-to-point
steps of the table stepper motor, can be used to produce motion
that is continuous while the airgun intermittently discharges, or
the movement can be keyed, meaning coordinated in timing to, the
successive discharges of the airgun, so that the muzzle-head is
made to intermittently travel a certain distance, wait in place
until the one discharge is completed, then resume travel to the
next implantation site.
[4321] In fact, the length of the pause in such intermittent
movement is variable from complete cessation that is initiated
before each individual discharge is triggered until after the
discharge has been completed to only a portion of the discharge
cycle, such as during recoil when, for example, it is more likely
that a miniball might escape. When positioning is not keyed to the
individual discharges, the overall distance and number of
discharges within this distance are specified. Provided a threshold
for the minimum interval to separate implants is not violated, the
control mechanism then spaces this number of discharges at equal
intervals within this distance.
[4322] To signal that implants have been placed too close together
in linear sequence requires an ability to relate the action of the
positioning table to the discharge of the airgun and consequent
points of successive implantation and to use an out of tolerance
condition to actuate an alerting device. As indicated, when
positioning is keyed to the individual discharges rather than
continuous, the positional cycle consists of movement in discrete
translational sub-incremental steps of the stepper motor as table
actuator from implantation site to implantation site, the
muzzle-head held stationary while the airgun discharges before
proceeding to the next implantation site. Intermittent action
comprehends two subcycles, which the positional control system is
used to coordinate.
[4323] One subcycle consists of the timing relations in the
operation of the airgun and barrel-assembly, which are only
slightly variable. The airgun is fully variable in the timing of
the initiation of discharges but not in the time of each discharge
(which depends upon the length of the barrel-tubes, hence, transit
time). The other subcycle consists of the pattern of transluminal
movement, which is fully variable. The airgun cycle consists of the
release of CO.sub.2 into the chamber, the transitting of the
barrel-tubes by the miniballs, the ejection of the miniballs
through the muzzle-head, and the time for the miniballs to
penetrate to the trajectory terminus.
[4324] The transit time varies as the length of the barrel-tubes,
but the absolute duration of this interval compared to that of the
fixed rate of transluminal repositioning is small. Since control
over the airgun mounting is fully variable while control over the
the airgun mechanism is only variable in its intragun discharge
cycle characteristics and thus only slightly in the absolute
overall duration of the cycle, the operation of the airgun mounting
is made to subserve the timing dictated by individual discharge
from chamber to implantation end-point.
[4325] In intermittent operation, the movement of the muzzle-head
or the fixed duration of each stop can be keyed either to the
actual or to the highest rate of discharge, or more specifically,
to the full, some portional, or the maximum time for an individual
discharge, the last providing an interval of time slightly greater
than needed with the longest barrel-assembly, thus eliminating the
need for adjustment in the feedrate and achieving relative
simplicity. That is, fixing the muzzle-head pause time for the
maximum discharge time, which is determined mostly by the
barrel-tube transit time, eliminates the need to adjust the pause
time even though with shorter barrel-tubes or a higher discharge
velocity the duration of this pause could be reduced. Accordingly,
to preclude human error, the pause time is fixed at the maximum
needed for the longest barrel-assembly
[4326] Because the perforated barrel-tubes disallow any buildup of
gas pressure, whether the result of premature discharge or in
discharge with continuous movement of the muzzle-head, the
shot-groups of successive discharges exert no effect upon the exit
velocity of one another even though the miniballs of the previous
discharge or discharges have not yet exited. Furthermore, with
continuous movement of the linear stage and muzzle-head during
discharge, a malfunction resulting in premature follow-on discharge
so that more than one shot-group traversed the barrel-tubes
simultaneously would have no jamming effect. Accordingly premature
discharge is to be avoided exclusively due to the misplacement of
implants that results.
[4327] XIII3f(2). Airgun Control Panel
[4328] To minimize human error, controls are mounted to the
apparatus contolled or to a separate base, but not to other
apparatus which may be in use simultaneously. The airgun control
panel therefore includes the controls for minimally ablation or
ablation and angioplasty-capable barrel-assemblies, which lack a
built in source of power and are dependent upon the airgun power
supply. Minimally ablation or ablation and angioplasty-capable
barrel-assemblies for use in blood vessels will usually incorporate
heat-windows and an embolic filter and sometimes radial projection
units built into the muzzle-head requiring controls in the airgun
control panel, other features such as blood-grooves, blood-tunnels,
and gas pressure diversion channels passive and requiring no
controls.
[4329] A radial projection catheter, whether used with a minimally
or fully ablation or angioplasty-capable barrel-assembly, will
similarly have its own controls. Regardless of the type of
barrel-assembly used, discharge and the transluminal and rotational
movement associated with successive discharge occurs only while the
barrel-assembly is inserted in the airgun. Accordingly, the control
panel for these functions is mounted not on the barrel-assembly but
as separate (remote) from the airgun, at the top of a stanchion
with weighted base and stand that may be raised to the height most
comfortable for the operator, or on the airgun. So that the
operator can call for immediate assistance, duplicate airgun
control panels are preferably in both locations, those mounted to
the airgun requiring enablement from the stanchion control
panel.
[4330] The airgun itself may be mounted at the top of a stanchion
or set on a table, but must be adjustable in height to level the
barrel-assembly with the patient. In contradistinction to
positional control for discharge, the functions assigned to the
barrel-assembly and more especially a fully ablation or ablation
and angioplasty-capable barrel-assembly--such as the deployment of
a radial projection units in order to nudge the muzzle-head to one
side of the lumen--are assigned to the control panel onboard the
barrel-assembly. Discharge is either a. 1. Concurrent or 2.
Delayed, and b. 1. Directly manual or 2. By executing
preestablished patterns, described as semiautomatic, in that once
the equidistant discharges have been manually set as to increment
(distance of separation), indicating the direction for the action
and depressing the plunger switch at the top of the joystick causes
the pattern to execute.
[4331] Concurrent manual control over movement is obtained by
holding down the plunger or dead-man switch at the top of the
joystick at the same time that the joystick is used to move the
barrel-assembly or rotate the muzzle-head, while delayed movement
is obtained by first positioning the joystick forward to
intraluminally advance, backward to withdraw, or to a preset angle
to rotate the muzzle-head, and thereafter depressing the plunger
switch. As a mode of semiautomatic operation, delayed execution is
used to reduce the risk of human error in the form of overshots
that would necessitate frequent if not irritating transluminal
reversals in direction.
[4332] The section above entitled Single Axis Linear Positioning
Table Airgun Mount specified that the operator first sets the
number and distance of point-to-point increments to separate the
starting and ending positions for the linear stage and then uses
the joystick to initiate the automatic execution of this pattern.
The apparatus then automatically moves the muzzle-ports forward or
backward to the successive target locations for discharge, with or
without rotation of the muzzle-head. More specifically, the control
panel includes control settings for initiating programs that
automatically discharge miniballs in preestablished formations,
that is, in preset discharge patterns that execute as unit
routines. The patterns are obtained by coordinating the
transluminal movement of the linear stage and rotation of the
muzzle-head with discharge.
[4333] Positional control thus involves the coordination of the two
drive axes, the one an open-loop controlled stepper motor that
moves the linear positioning table for transluminal movement, and
the other, a closed-loop controlled dc servomotor that rotates the
muzzle-head with actuation of the airgun push solenoid used as a
hammer to strike the valve body pin. Such action is obtained
through a programmed sequencer or stack register that stores the
sequence of instructions for executing the pattern as a collective
stream unit or routine. The sequencer controls the two servodrive
controllers-amplifiers. In practice, the servodrive is usually a
two-axis unit that is able to control a closed and an open loop
simultaneously. As indicated, a pattern can include transluminal
and rotational reversal, with discharge effected at each stop.
[4334] An automatic pattern is selected with a control knob having
a pointer that is moved to the pattern chosen, and then the
direction as forward (intraluminally advancing) or withdrawing
(intraluminally retreating) is indicated by moving the joystick
forward of backward respectively, and the action initiated only
after the plunger switch atop the joystick is taken off safety and
depressed, at which time the sequence consisting of moves to a
succession of discharge points proceeds automatically. Pushing a
cancel or check button on the control panel instantly stops
(abends) this action. Rotational repositioning of the muzzle-head
is directed by the program and executes, and coordinated timing
exceeding the capability of the operator, without the need to
rotate the joystick.
[4335] Rather than serving as a move execution switch to reposition
the muzzle-head, in the control of discharge, whether directly
manual to discharge one or a plurality of miniball implants or to
initiate an automatic discharge pattern, the function of the
plunger switch is as a trigger, and each terminus of travel a point
for discharge. Whether to move or discharge, the on-off switch must
be set to `on,` and depressing the plunger switch always
necessitates unlocking the safety. As additional safeguards,
discharge during movement is electronically disabled, and a
check-action or cancellation button positioned beneath the thumb of
the operator on the joystick handle instantly truncates the ongoing
action.
[4336] More specifically, depressing the `cancel` button stops the
flow of current to the turret-motor (rotatory axis), airgun linear
stage (transluminal axis), the pattern instruction program, and
airgun discharge actuating push solenoid to instantly arrest action
commanded before or once initiated. While discharge could proceed
so that miniballs were released while the muzzle-head continued to
move, needless complexity and risk is avoided by not allowing
movement and discharge simultaneously; rather, movement
electronically disables discharge, which is automatically enabled
on reaching the end of travel. The positional controls mounted to
the airgun are for use only with the barrel-assembly inserted and
are intended solely to move the muzzle-head from one location for
implant discharge to the next.
[4337] As indicated, when the implants must be placed too closely
together for manual control, upon depressing the trigger,
transluminal movements of several millimeters or degrees of
muzzle-head rotation are accomplished semiautomatically. In
addition to the on-off switch, plunger switch safety lock, and
action cancellation button, the airgun or stenting control panel
typically includes controls for positioning:
[4338] 1. Turret-motor rotation (typically by means of a digital
encoder manually rotated by the rotary or tilt right or left
component of the joystick (cyclic) with a pointer moved above an
upper semicircular calibration with apical or centered 0-point (set
point) and marked off in 5 degree error signal increments to either
side).
[4339] 2. An advancement and withdrawal control for direct manual
transluminal movement with the linear positioning table by preset
increments of a number of millimeters, the direction and execution
controlled by moving the joystick forward to advance or backward to
withdraw.
[4340] 3. Advancing the intraluminal barrel-assembly in increments
of two millimeters with the linear positioning table by pushing the
joystick forward or backwards to withdraw.
[4341] 4. Action cancellation or checking switch to instantly
truncate the action whether mid-repositioning or mid-discharge,
regardless of whether the action is direct manual or semiautomatic
as a patterned sequence or collective unit formation; and controls
for discharge.
[4342] 5. Discharge pushbutton or plunger type switch at the top of
the joystick for executing positional, discharge, and semiautomatic
control.
[4343] 6. Automatic discharge pattern selection knobs, transluminal
(linear stage) positioning generally in increments of two
millimeters and rotation (turret-motor) generally in increments of
5 degrees; and
[4344] 7. Recovery (tractive) electromagnets 1 and 2 low-off-hi
toggles. The cancel and actuation keys on both the control console
and an angioplasty barrel-assembly pose sufficient resistance to
depression to minimize the risk of unintentional depression.
[4345] XIII3f(3). Relation of Control Panels to the Turret-Motor
and Airgun Linear Positional Table Axes, to Discharge, and to One
Another
[4346] Control of the airgun linear positioning table consists of
using the switches and joystick on the airgun control panel, which
is mounted on a bottom-weighted stanchion. Although the
barrel-assembly can be inserted into the airgun barrel for motor
controlled positioning at any time, angioplasty can be entirely
manual, the operator manipulating the barrel-assembly at its free
proximal end. Motor controlled advancement and withdrawal of the
intracorporeal barrel-assembly is thus essentially limited to
implant discharge or stenting use of the barrel-assembly. That is,
while some conditions will recommend stent-jacketing prior to
implantation, in most instances, stenting will follow use of the
barrel-assembly manually with the proximal end freely movable.
[4347] Implantation then requires insertion of the barrel-assembly
into the airgun, the rest of the transluminal positioning of the
barrel-assembly performed by means of the linear positioning table,
and rotation of the muzzle-head by means of the turret-motor. As
seen on the airgun control panel shown in FIG. 85, the operator or
an assistant can use the table to advance or withdraw the
muzzle-head continuously or by a certain number of steps where the
size of each step is set with a neighboring control knob. The
airgun linear positioning table is preferably of the stepper
motor-driven lead screw kind under open-loop control. A four-way
radially symmetrical muzzle-head advanced by the linear positioning
table will lay down lines of implants at uniform longitudinal
distances to define the quadrants of the ductus.
[4348] As shown in FIG. 85, to produce a close formation of
implants in order to evenly distribute the tractive force, the
turret-motor and linear stage can be semiautomatically controlled
to advance or reverse transluminal movement, the operator directing
each run by entering the linear distance and number of discharges
desired. At the end of each linear run, the turret-motor is used to
adjust the rotational angle and the linear stage is then used to
linearly distance the discharges in the reverse direction.
Alternatively, the turret-motor can be used to rotate the
muzzle-ports at each level without reversing direction so that the
muzzle-head advances intermittently but consistently distad or
withdraws thus proximad.
[4349] XIII3f(4). Automatic Close-Formation Pattern
Implantation
[4350] While stereotypical or iterative pattern generation is a
mainstay of numerical control in piecepart manufacturing, the
functionality of automatic pattern generation for the present
purposes would be inappropriate. In a clinical setting, complete
flexibility subject to the medical judgment and immediate control
of the operator is paramount. Detailed medical aspects of the
actual lesions demanding treatment represent the primary factor in
the decision process, mere niceties of technology impertinent.
Discharge patterns would have to exist in so many variations of
overall size and shot density that an absolute number of such
patterns would be needed as would promote human error in
selection.
[4351] Any such capability would most likely promote a dependence
upon a generalized patterns where these were not properly applied.
In order to be adapted for any real set of lesions, prepackaged
patterns would have to be variable in omitting or adding implants
to an extent that would render the nominal patterns useless.
Accordingly, even though it would be a relatively simple matter to
make discharge of entire formations execute automatically as a
complete pattern, the concept is discounted in principle.
[4352] XII14. Pairing of Barrel-Assembly and Airgun
[4353] Provided the gauges match, any barrel-assembly can be
connected to any airgun. For any given procedure, the requirements
for precision in discharge independently determine the suitability
of a given airgun, and the requirements for versatility and
precision in ablation or angioplasty independently determine the
suitability of a given barrel-assembly. Depending upon the
procedure, either may be simple while the other complex. Both
airguns and barrel-assemblies are applicable to procedures that
demands less complexity and expense. The reverse is not true, in
that a simple airgun will not allow the degree or speed of control
in exit velocity essential for moving directly and without testing
between histologically or pathologically different tissues, and to
perform an ablation or angioplasty requires a barrel-assembly made
for this purpose.
[4354] The opposing extremes in application are represented by
differentiated anatomy, such as that in the trachea, which requires
point-to-point discharge under the direct manual control of the
operator without the need to clear the lumen of obstructive tissue,
and a requirement for an even distribution of miniballs to
uniformly distribute stent-jacket magnetic force over an area of
undifferentiated anatomy in a straight arterial segment after the
lumen has been cleared of stony plaques. Reversal of a collapsed
dorsal membrane by a veterinarian, for example, can be accomplished
with a simple pipe, as addressed above in the section entitled
Simple Pipe-type Barrel-assemblies, connected to a suitably
modified air pistol, as addressed above in the sections entitled
Simple Airgun with Limited Application and Modified Simple Airgun
of Wider Application, et seq.
[4355] The former uses a basic barrel-assembly and airgun, but
depends upon a high degree of skill on the part of the operator,
whereas the latter demands not only skill but an airgun that
affords finely and quickly adjustable control over the timing,
placement, and force of discharge and a barrel-assembly that
provides multiple means for preparing the lumen to be implanted.
Using the simple pipe with modified handgun, off to a side
discharge with force impact registration film can be used to adjust
the exit velocity with the valve body slide, as addressed in the
section entitled Control of Propulsive Force or Exit Velocity by
Means of a Calibrated Slide Cover over a Slot Cut into the Valve
Body.
[4356] An ablation or ablation and angioplasty-capable
barrel-assembly is intended to be usable with or without stenting.
When used for stenting, work in the vascular tree demands a
precision airgun mounted to a linear positioning stage with the
controls appurtenant thereof included in its control panel.
Directly manipulable barrel-assemblies include simple pipes, which
only used for discharge implantation, are always connected to an
airgun, minimally ablation or ablation and angioplasty-capable
barrel-assemblies, which meant for simpler ablation or angioplasty
during implantation, are also used while connected to an airgun,
and ablation or ablation and angioplasty-capable barrel-assemblies,
which are removed from the airgun when used to perform an ablation
or an angioplasty, regardless of whether implantation discharge is
to follow.
[4357] For freedom of movement when the implants do not require to
be placed so close together as to exceed manual guidance, direct
manipulation of the minimally capable barrel-assembly, like the
simple pipe, is accomplished with an air pistol. The power required
for the recovery electromagnets, turret-motor, and any radial
projection units is provided by a battery pack is contained within
a housing that extends the butt of the pistol grip downwards.
Control microcircuits for heat-windows that use actuator windings
as the heat source and control of the turret-motor are likewise
contained within this housing, with the control panel mounted to
its side.
[4358] By contrast, in an ablation or ablation and
angioplasty-capable barrel-assembly, these components are
associated not with an indissociable airgun, but rather with the
barrel-assembly. The control panel is described in the sections
entitled Airgun control panel and Relation of Control Panels to the
Turret-motor and Airgun Linear Positioning Table Axes, to
Discharge, and to One Another. The pairing of modified air pistol
with an ablation or ablation and angioplasty-capable
barrel-assembly is not preferred as awkwardly involving duplicate
battery packs, hand grips, and controls.
[4359] XIII5. Remote Controls
[4360] The size of the pack that must be added to a modified
commercial air pistol for supplying power to the powered components
in a minimally ablation or ablation and angioplasty-capable
barrel-assembly or to the hand-grip of an ablation or ablation and
angioplasty-capable barrel-assembly can be reduced if the controls
and microcircuit outputs generated through use of these controls
are separately housed with the microcircuits in a remote control
unit. A hand-held remote control unit for use with a minimally
capable barrel-assembly is faced by the control panel therefor and
detachably mounted to the enclosure of the obligatory airgun. That
for an ablation or ablation and angioplasty-capable barrel-assembly
is detachably mounted to the onboard battery pack for use in-situ
or at a distance by an assistant. The transduction and infrared
transmission of such signals is well known from the prior art.
[4361] XIV. Modes of Failure
[4362] The likelihood of a failure to implement suitable
precautions because the operator was unaware that a vulnerable
structure lay along the trajectory and failed to take prescribed
measures for accommodating this condition is slight, the size of
the projectile limits the injury that could be inflicted, and
perforations tend to seal quickly. A primary reason for ballistic
implantation is precisely the fact that the trajectory through the
tissue to the target location is no larger in diameter than is the
implant, and therefore quickly seals and quickly heals. Moreover,
once placed, the ductus-intramural implants to be described become
integrated into, move with, and effectively become a part of the
surrounding tissue.
[4363] XIV1. Failure to Properly Discharge
[4364] Use of the in situ test described below, which intrinsically
tests the exit velocity of the apparatus to be used in relation to
the tissue it is to be used upon, should avert incorrect settings
of the exit velocity.
[4365] 1. If the exit velocity is set too low, the miniball may
fail to eject. Retrieval of the miniball is accomplished by running
a barrel-tube ramrod with mildly magnetized tip down the
barrel-tube.
[4366] 2. If the miniball ejects without sufficient momentum to
penetrate the lumen wall, whether it becomes stuck between the
muzzle-head and the internal surface of the lumen wall or drops
into the lumen, if not embedded within the soft inner layer by the
outward force of the smooth muscle action of the passing pulse or
peristaltic wave, the miniball is retrieved by the recovery
electromagnets or trap filter, deployment of the latter being
imperative in the bloodsteam. To time discharge for impact to occur
at just the right moment when the wave passes is unrealistically
difficult until several discharges allow this interval to be
clocked.
[4367] 3. If the miniball penetrates the lumen wall to too shallow
a depth, it is extracted and recovered by increasing the current to
the closer recovery electromagnet.
[4368] 4. The reasons for placing a stent-jacket before initiating
discharge are stated above under the section entitled Double-wedge
Stent and Shield-jacket Rebound-directing Linings. If the miniball
just punctures the adventitia at a tangent point, then its
functionality for retracting the wall of the ductus cannot be
depended upon and it must be replaced nearby.
[4369] 5. If the miniball punctures the adventitia without
sufficient momentum to rebound, it becomes embedded within the
lining, and since the stent-jacket is applied to encircle the
substrate ductus at its quiescent diameter, entrapment within the
lining is accelerated by the outward forces of the smooth muscle
action within the ductus. If the miniball interim finds a gap
between the adventitia and lining, it innocuously either becomes
trapped between the two and either forced into the inner softer
layer of the lining or dropped into the body cavity.
[4370] 6. If the miniball perforates the substrate ductus with
sufficient residual momentum to strike the harder outer layer of
the lining that is inclined (canted) outwards (centrifugally)
moving ahead (forward, downstream, distad), the miniball will
rebound to a functional location distal to that intended. The exit
velocity is corrected and the miniball replaced. If the miniball is
one of a plurality of miniballs radially discharged together, then
depending upon the density of implants, the failure is disregarded
or a rotary magazine clip with all but the one miniball position
blanked is used with adjusted exit velocity to replace the
miniball. Miniballs discharged in automated mode are by definition
sufficiently dense to discount isolated discharge failures.
[4371] XIV2. Shallow Termination Into the Lumen Wall or Other
Tissue of the Trajectory
[4372] The miniballs are discharged to enter the ductus wall at an
acute forward angle, so that an unexpectedly malacotic or
delaminated segment would result in an overshot, meaning
penetratation to a terminus that is too distant from the position
intended both radially, or as to depth into the wall, and
longitudinally, meaning continuation too distant in the antegrade
direction. Depending upon the distribution of any sclerotic tissue
within the segment, the miniball could fail to reach the depth
intended, and a heavily calcified plaque or salt-encrusted ureter,
for example, could cause a rebound into the lumen.
[4373] The means for averting and neutralizing these eventualities
have been addressed in numerous sections, to include those
pertaining to pretesting tissue hardness under section XVII below
entitled Testing and Tests, the preplacemnt of shield or other
jacket, double-wedge jacket linings, impasse-jackets, and the use
of tissue hardness altering agents, among others. Trajectory
terminus is readily discernible by passing a fine catheteric solid
state Hall effect magnetometer microprobe through the access
incision and along the adventitia, a high cost superconducting
quantum interference device or a physical properties measurement
system not necessary for the purpose as well as requiring
temperatures injurious to tissue.
[4374] Provided the muzzle-head has been degaussed, such a sensor
can be passed down an unused barrel-tube as service-channel and the
muzzle-head passed over the length of the ductus to the maximum
distance that the miniball might have penetrated. Even if coated
with highly radiopaque tantalum, the miniballs are very small,
generally 1.14 to 1.52 millimeters in diameter, making confirmation
of successful implantation with imaging equipment difficult.
However, since there is a range of forces that will substantially
assure penetration through the luminal wall as not to terminate
short of the more penetration-resistant outer tunic, which is
harder and more elastic than the tissue subjacent to it, and since
a value toward the upper end of this range is chosen to minimize
the chance of shallow placement, only airgun malfunction or human
error in setting its controls can result in shallow placement.
[4375] Miniballs and stays are given a coating of adhesive or
protein solder to avert dislodgement into the lumen, and a
down-tract or downstream trap-jacket, as addressed above in the
section entitled Concept of the Impasse-jacket will prevent
continued travel. For abaxial tissue within the wall of the ductus,
the tractive force on the misplaced miniball should not be
sufficient to induce compression necrosis. Necrotic tissue abaxial
to the miniball should allow it to pass through and out of the
wall, nullifying its value for stenting but not capable of causing
harm. Again, means for predetermining the propensity of target
tissue toward such an eventuality and means for neutralizing any
complication that would result are addressed in numerous
sections.
[4376] Provided antibiotics are administered this is a
self-correcting problem, the perforation spontaneously healing.
Unless contaminated through negligence or mishap, all of the
components involved are sterile, and antibiotics are routinely
administered as a precautionary measure in any event. Fistulization
occurs when infection or tissue necrotic due to chronic irritation
erodes a pathway to the exterior and drains. Shallow termination
does not, therefore, pose any significant risk. When the operator
sees that a miniball has landed short and negligible risk
notwithstanding prefers to extract it, a tractive electromagnet at
the front end of the muzzle-head is directed at the defective
implant with the muzzle-head turret-motor, and the current to the
electromagnet gradually increased until the miniball dislodges and
becomes trapped in the tractive magnet antechamber.
[4377] When the treated ductus abuts upon an interposed structure
that limits its gross movement toward the direction of traction,
and the implants are eccentric or toward one side, or in the
longitudinal half of the lumen but not the other side, it is also
feasible to pass an external electromagnet such as that described
below over the defective implant, as addressed above in the section
entitled Mishap Recovery. Since the miniball or miniballs short of
the termination intended will be lodged in softer, usually smooth
muscle tissue, these can be pulled into the correct position,
whereas those correctly placed will be prevented from perforating
by abutment against the harder and more elastic adventitia.
[4378] This process therefore has the effect of selectively forcing
a shallow miniball or miniballs out to, but not through, the outer
tunic. Trajectory overshot with perforation. Provided antibiotics
are administered to control bacteria that are always within the
body, this is a self-correcting problem, the perforation
spontaneously sealing then healing. The miniballs are bioinert and
sterile. If an overshot could penetrate another vessel to enter the
bloodstream, then the stent-jacket or clasp-wrap to be used with a
stent-jacket and the stent-jacket are applied before commencing to
place the miniballs. Loss of a miniball or miniballs in the lumen.
So long as the trap-extraction electromagnets in the front end of
the muzzle-head are set to trap field strength throughout the
procedure, any miniball or miniballs that become loose in the lumen
are swept into an electromagnet antechamber.
[4379] The proper functioning and setting of the trap-extraction
electromagnets are confirmed preoperatively, and once the
barrel-assembly has been introduced, the ammeter on the airgun, as
will be described, will immediately reveal a loss of current. Since
in exceptional instances when collateral circulation is lacking the
loss of a miniball in the circulatory system could result in
ischemia and necrosis, a transfer switch to a temporary power
source such as an automotive battery may be used to sustain current
to the electromagnets in the muzzle-head during the interval until
the generator comes on. This merely states that an emergency
uninterreuptible power source should always be on hand. The use of
an external electromagnet of the kind described below can be
positioned downstream to seize hold of any loose miniball or
miniballs, which are then recovered by increasing the current to
the electromagnets in the muzzle-head while reducing the current to
the external electromagnet.
[4380] XIV3. Perforations
[4381] Perforations are not usually the result of equipment
malfunction but rather human error--errors in testing, diagnosis,
or adjustment of the controls. When anticipated, perforations are
precluded by prepositioning of the stent-jacket, which is usually
of the double-wedge rebound type as described above in the section
entitled Double-wedge Stent- and Shield-jacket Rebound-directing
Linings. Without prepositioning the stent-jacket, perforations by
miniballs of 0.4 to 1.0 millimeters in diameter still have limited
potential to cause significant injury. For the ductus treated, the
site of puncture will be no more thrombogenic or less medically
manageable than when implantation is successful. In the vascular
tree, the prepositioning of a stent-jacket to prevent perforations
may warrant the additional prepositioning downstream of an
impasse-jacket to seize any miniball that rebounds into the
bloodstream.
[4382] Perforations of the gastrointestinal tract are addressed
above in the section of like title. Barring human error in having
set the exit velocity far too high, the residual momentum of the
miniball after it has penetrated through the wall of the ductus
treated is not likely to pose a significant threat for neighboring
structures. For such an error to be so extreme that the miniball
could penetrate to the interior of a neighboring vessel to become
an embolism, for example, is fanciful. Such injury as could result
is more realistically associated with nervous structures. See also
the section above entitled Concept of the Extraluminal Stent and
the Means for Its Placement.
[4383] XIV4. Jamming
[4384] Jamming is associated with firearms where the round
(cartridge, projectile) is cylindrical and engaged in a rifled
barrel, so that deviation from concentricity can cause the casing
to seize against the inside of the barrel. Here, in marked
contrast, the barrel-tubes are completely smooth, usually lined
with a coating of polytetrafluoroethylene, and the miniballs
spherical. This makes jamming extremely unlikely. Moreover, because
the rotary or linear feed magazine clip is readily examined, the
failure of a miniball to eject is immediately discernible. Except
for the interior of the barrel-assembly not engaged within the
barrel of a modified commercially sold airgun, a jam inside a
barrel-tube is readily viewable fluoroscopically.
[4385] XIV5. Premature Follow-On Discharge
[4386] Premature follow-on discharge with the muzzle-head moving
from implantation point to point so that more than one shot-group
traversed the barrel-tubes at the same time would not result in
detention of the follow-on discharge. The perforated barrel-tubes
disallow a buildup of gas pressure before the follow-on miniballs
that could affect exit velocity even though the previous discharge
had not yet exited. Premature discharge would, however, result in
implant misplacement.
[4387] XIV6. Endothelial Cling and Seizure
[4388] The muzzle-head is surfaced for slipperiness, usually with a
fluoropolymer such as polyetrafluoroethylene. Because the diameter
of the apparatus is preselected for the ductus to be treated, and
the surface material of the muzzle-head is lubricious and may
additionally be wetted with a lubricant, clinging or seizure of the
muzzle-head against the surrounding lumen is improbable. Should
such occur nevertheless, a lubricant such as ACS Microslide.RTM.,
Medtronic Enhance.RTM., Bard Pro/Pel.RTM. or Hydro/Pel.RTM., or
Cordis SLX.RTM. is ejected through a catheter passed down a
service-channel, or the central channel in a combination-form
barrel-assembly, or by means of an electric-fluid system-neutral or
fluid ejection tool-insert and an interval allowed for the
lubricant to disperse.
[4389] The same is done when a radial projection catheter or
combination-form radial projection catheter becomes stuck. The
turret-motor is then used in oscillatory or chatter mode to further
spread the lubricant in between the lumen wall and the muzzle-head.
The same is done to expedite passing the barrel-assembly through
tighter curves. Such eliminates the need for gross movements of the
barrel-assembly that would be more likely to cause injury. Once
confirmed free, the barrel-assembly is withdrawn. See also the
section below entitled In situ Muzzle-head Adhesion Test.
[4390] XIV7. Radial Projection Unit Lift-Platform Malfunction
[4391] If the radial projection unit is piped, then retraction can
be forced by bulb or syringe pipetting or connecting it to an
aspiration pump at the proximal end, whether end or side-socketed.
Lift-platforms for use in nonpiped units must incorporate
ferromagnetic material for retraction (lowering) and raising by
means of the magnetic force exerted by an external hand-held
electromagnet.
[4392] XIV8. Entry of a Miniball Into the Bloodstream
[4393] The interception from continued travel and retrieval of a
miniball that enters into the bloodstream is addressed above in the
sections entitled Concept of the Impasse-jacket and Interception
and Recovery of a Miniball Entering the Circulation, among
others.
[4394] XV. Arcuate Stays
[4395] Arcuate (arciform, arcate) stays are implants that are
inserted nonballistically beneath the surface of an organ, body
wall, or the wall of a collapsed or stenotic ductus by means of
special hand tools to be described. Some stays consist entirely of
medication and are completely absorbed, while others used to
provide mechanical support as buttresses may be absorbable when
self supportability is expected to return, or permanent
(nonabsorbable), or permanent and coated with absorbable substances
such as medication, hardening, or bonding agents. Whereas medicinal
miniballs require no stent-jacket and therefore require entry to
insert the barrel-assembly, stays exclude a transluminal component
but require an access incision local to the point of insertion.
[4396] In an ideal stay, the arms, or extensions of the stay from
the midline, would flex as do those in an unstrung archer's bow;
however, a number of prior considerations for treating a given
condition often preclude formulation of the stay to meet this
requirement. When flexibility is lacking, the tips of a stay will
resist movement of the surrounding tissue in proportion to the
length or arcuate extent of the stay about the wall of the ductus
for the degree of change in lumen caliber or circumference. When
this is true, inflexible stays are kept short and made larger in
width to present a larger and more uniformly distributed area to
the tractive force.
[4397] Stays are inserted one at a time from outside the ductus
through the local incision, which takes longer but allows each
insertion to be of a different kind or size of stay and for each to
be confirmed as properly positioned before proceeding to the next.
Stays of any kind pose less potential for retrieval problems than
do miniballs, but to allow retraction with the electromagnet built
into the insertion tool should insertion deviate from the path
intended, even medicinal stays, which are completely absorbed,
include some ferromagnetic matter. Stays referred to as stent-stays
are used with a circumvascular stent-jacket or more distant
magnet-wrap, subcutaneous, or suprapleural clasp magnets, and some
of which are nonmagnetic to maintain luminal patency.
[4398] XV1. Medication or Radiation (Nonstent), and
Medication-Coated Stays
[4399] Stays can be formulated to consist entirely of medication,
of different kinds of medication in concentric layers where each
consecutive subjacent layer is time-released spontaneously or by
extracorporeal action, as has been delineated for miniball
implants. Other nonstent stays can emit radiation from a core seed
or following irradiation. Absorbable stays can release medication
as these dissolve and serve with or without a stent-jacket as
temporary buttresses or structural supports over the period of
healing and dissolution. Nonabsorbable stays can be drug eluting,
or if incorporating a chemically isolated core of strongly
magnetized neodymium iron boron, can serve to attract drug carrier
particles from the passing lumen contents into the intervening wall
of the ductus.
[4400] Stays generally contain sufficient superparamagnetic
magnetite or maghemite nanoparticles or finely grained powder to
allow recovery with a hand-held electromagnet if misplaced or
dropped, and when meant for stenting use, have a ferrous core or
distributed encapsulated ferrous material for use as magnetic
stent-stays. Like miniballs, addressed above in the section of like
title, stays can be given outer coatings which can be affected by
passive heating, and size allowing, can incorporate internal means
for generating heat. If magnetized, stays like miniballs can be
used to attract magnetically susceptible drug carrier particles up
to the depth into the ductus wall. Impasse-jackets and
stent-jackets are not limited thus nor in the mass of magnetized
material that these can incorporate. Ductus-intramural implants are
therefore suited to the treatment of lesions which are small,
circumscribed, and shallow (adluminal).
[4401] XV2. Arcuate Stent-Stays (Stent-Ribs) for Use with Magnetic
Stent-Jackets
[4402] Stays to serve as the intraductal component of a permanent
extraluminal magnetic stent have a solid core or dispersed cores of
ferrous metal encapsulated for chemical isolation. Those for
temporary magnetic stents have superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder dispersed in an
absorbable matrix, such as polyglycolic acid. Upon dissolution of
the absorbable stay, the iron is assimilated by the body. Drugs for
delivery as stays to achieve focused concentration likewise include
sufficient dispersed superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder to allow any that become
mispositioned to be easily retrieved.
[4403] The stay insertion tool described below includes an
electromagnet for the quick retrieval of these. Absorbable stays
can also be made to liberate medication during dissolution, and
numerous combinations of medication in different type stays are
possible. Broadly, whether for sustained attractability or for one
time recoverability virtually all stays contain some ferrous
content. While compared to ballistic implantation, using stays will
usually lengthen overall procedural time, depending upon the
specific condition to be treated, stays can present significant
advantages over ballistic implantation.
[4404] Peripheral arteries may allow stays to be implanted with or
without clamping, but unless the heart has already been shunted
(bypassed) for an open heart procedure, stays are not for use at or
close to the heart. While constant movement will affect the
precision of miniball placement, this is unlikely to result in
adverse consequences. This is because the increased force of impact
to perforate and not just penetrate is large, and miniballs
misplaced in level can be disregarded or the stent-jacket extended
to include these. The discrepancy may call for the use of a
segmented stent-jacket.
[4405] XV3. Sructure of Stays
[4406] Stays have either razor sharp pointed or flat edges at the
leading edge or at both the leading and trailing edge. Stays with
flat front and rear edges are preferred as affording a greater area
that delivers a larger quantity of medication and/or preserves
concentricity with the wall of the ductus. Straight edged stays are
driven forward by a stay insertion tool having an ejection tongue
that has a flat front edge. Flat-edged stays are not wider midway
along their length as to require engagement by the leading edge of
the insert tool ejection tongue to ensure straight ejection. Stays
with a pointed rear edge are used to gain penetration and/or to
avoid vulnerable periductal microstructure and are driven forward
by a stay insertion tool having an ejection tongue that has a
forward v-shape with the apex of the v pointing rearwards to
complement to the rear-pointing edge of the stay.
[4407] The fit and depth of tongue overlap must cause the stays to
eject without veering. The advantages in the use of stays, mostly
related to avoidance of the lumen, are addressed below in the
section entitled Circumstances Dissuading or Recommending the
Application of Stays. Even though the insertion tool is configured
for a minimal girth so that it can be slipped down through a small
surface incision and is equipped with clips to attach an endoscope,
because stays are inserted from without the ductus through the
adventitia, the application of these implants is least hindered and
quickest when used during a procedure that calls for open exposure
in any event.
[4408] When a magnetic stent to extend over a small segment of the
ductus is required, the fact that to place the stent-jacket
requires access to the ductus from without makes the use of
stent-stays quicker, eliminates the need for a collateral
transluminal procedure, and means that the lumen is not entered.
Some eccentric or radially asymmetrical conditions are correctible
ferromagnetically whether implanted ballistically or applied
nonballistically with clasp-wraps or stays while others do not
warrant ballistic implantation or magnetic traction. The latter can
be corrected with stays made of plain plastic, nonmagnetic use
being peculiar to nonmagnetic stays.
[4409] As is true with magnet and clasp-wraps, when the ductus to
be treated is extensively attached by connective tissue,
circumferential implantation may have to be intraluminal or
ballistic. Stays are usually textured and/or perforated for added
stabilization by tissue infiltration over time. A deeper surface
texture also allows more medication or cement to be introduced
ductus-intraparietally (ductus-intramurally) by the stay as it
passes through the insertion incision produced by its leading tip.
The tissue gradually supplants the substance adherent within the
surface grooves or depressions.
[4410] Such a surface texture is no less applicable to nonmagnetic
implants, such as nonstent-stays, that is, miniballs and stays not
meant for use with a stent-jacket, but rather consisting entirely
of medication, an irradiating seed, both, or stays that are
introduced to support, or buttress, a collapsing ductus. When not
temporary as absorbed, temporary placement may still be desirable.
For example, irradiating seeds implanted on a temporary basis,
allow a certain dose-rate exposure over a certain period of time.
That stays are extracted as well as introduced from outside the
lumen can be advantageous. In an artery, this avoids the need to
administer systemic platelet blockade or anticoagulants, while in
the colon, the risk of infection is reduced.
[4411] The depth of surface texture and any outer coating respond
to the probable term that the implant will remain in place as well
as the condition treated. While necessitating reentry at a later
date, stays can be extracted with the same tool that is used to
place these with or without stays loaded. This allows any kind of
nonabsorbable stay, such as an irradiating seed stay of higher
dose-rate, to remain in place over a limited period. Stays for
later recovery contain ferrous metal, either as a core or as
dispersed, to allow magnetic retrieval. Extraction is accomplished
with the aid of a slitting edge that is retracted into the bottom
of the tool butt when not in use.
[4412] The slitting edge is released by means of a spring button
located within a recess at the side of the tool butt which requires
inserting and pushing with the point of a pin to release. To
extract a stay, the cutting edge is used to slit the overlying
adventitia, the insertion tool retractive electromagnet to withdraw
the stay, and the inmate cement line to seal the slit. Extraction
less demanding of normal approach than insertion, use of a tool
with the tilt-end component addressed below in the section entitled
Stay Insertion Tool with Pivoting Base, wherein the slitting edge
is retracted into the butt-pad, addressed in the section below
entitled Butt-pad with Retractable Slitting Edge, is
advantageous.
[4413] Since a stay that has been extracted will be retained at the
bottom of the tool until withdrawn from the body, when each
retraction slit is to be re-sealed with cement, the extracted stay
will interfere with the extraction of more than one stay at a time.
When the extraction slits need not be re-sealed, as when insertion
was relatively close to the periphery, the number of stays that can
be extracted at one time depends upon the field strength of the
magnet. As shown in FIGS. 86 and 92 thru 94, stays are mildly
curved (bowed, cambered) strips or bands made of a nonmagnetic
material, such as thin and flexible stainless steel or polyester,
that is hard enough to allow a leading edge to incise through the
external surface of the ductus.
[4414] To provide a superior surface for the adhesion of medicated
coatings or adhesives that will also promote tissue infiltration,
the surfaces of the ductus-intramural implants described herein,
stays and miniballs, are textured. When ferromagnetic, a soft iron
disk is chemically isolated as embedded at the center of the stay
and so that the force exerted on the disk will not cause the stay
to rotate injuring the lumen wall. As can miniballs, and
clasp-wraps, ferromagnetic stays can be used with stent-jackets or
magnet-wraps. Whether implantation is of spherules ballistically or
stays manually, the stent-jacket employed is unaffected, the
content herein unified in this regard.
[4415] Stays can be coated as described for miniballs, either of
which may also be surface coated with an antibiotic polymer such as
produced by Covalon Technologies, Mississauga, Ontario. In some
instances, stays are applicable without a stent-jacket, hence, the
need to include ferromagnetic material. Stay insertion tools are
described below in the section entitled Stay Insertion Tools and
the use thereof below in the section entitled Use of Stay Insertion
Tool (Stay Inserter). As addressed below in the section entitled
Stay Insertion Tool with Pivoting Base, the insertion tool may
incorporate a flexible joint toward the working tip that by making
possible some lateral reach to adjacent segments of the ductus,
allows the use of smaller and fewer stay entry incisions.
[4416] Stays for use with a tool incorporating a pivot joint should
have a periphery or surrounding edge sufficiently rounded and upper
and lower surfaces that are sufficiently flat so that each stay
will track past the bend under the force of the stay compression
spring without resistance or misalignment as would jam the line and
seat flatly against the floor of the ejection slot. All types of
stays, whether including ferromagnetic material for use with a
magnetic stent-jacket or consisting entirely of medication, some
combination of these, or including an irradiating seed, can be
perforated, surface textured, porous, ribbed, raised-rimmed, or
dished out on the front and back surfaces to thwart migration and
promote adhesion and tissue infiltration.
[4417] To allow retraction by means of the electromagnet built into
the stay insertion tool as described below in the section entitled
Stay Insertion Tool Inmate Stay Recall (Retraction) and Recovery
Electromagnet or recovery using the inmate or an external magnet,
stays of virtually every kind, to include those designated `pure
medication stays,` contain some superparamagnetic magnetite or
maghemite nanoparticles or finely grained powder. When it is
desired to coat stays with cyanoacrylate cement, for example, in
addition to a solid protein solder or another adhesive coating, but
too much of the cyanoacrylate cement is wiped or squeegeed off the
upper surface of the stay upon insertion through the adventitia, a
tool of the kind that ejects the cement prior to each stay as shown
in FIGS. 87 thru 91 is used with stays having a grooved or ribbed
and textured surface which carries more adhesive forward as it
passes through the adhesive into the wall of the ductus.
[4418] It is also possible to attach a microcatheter of the kind
described below in the section entitled Cyanoacrylate Injection
Catheter to the stay insertion tool by means of the spring clips
described in the section below entitled Binding of Lines and Cables
Alongside the Stay Insertion Tool. However, the secondary injection
of an adhesive such as a cyanoacrylate is not recommended when the
ductus and stays are so small that the adhesive cannot be
introduced through the same incision as was made by insertion of
the stay, or the stay insertion incision. The insertion tool
recovery electromagnet energizable with reduced field strength
throughout the insertion process, stays with a ferromagnetic core
pose little risk of entry into the lumen.
[4419] For ease of retrieval, structural support stays that would
otherwise consist entirely of absorbable aliphatic esters and stays
that would otherwise consist entirely of medication are admixed
with superparamagnetic magnetite or maghemite nanoparticles or
finely grained powder. Coating each stay with cyanoacrylate cement
as it is ejected reduces the risk that a stay will penetrate
through the intima and escape into the lumen. Since this would
squeegee away cement from the leading or incisive tip of the stay
causing the cement to be retained intraparietally, entry into the
lumen of cement, much less a stay, poses little risk. Moreover,
unless the time to initial set has been much extended with
retardants, cyanoacrylate cements will have `locked up`
superparamagnetic magnetite or maghemite nanoparticles or finely
grained powder allowing retrieval of the drop and not just the iron
particulates.
[4420] Even greater precaution against entry into the lumen is
achieved by prewarming the ductus or initiating warming upon
introducing the cement. A `cooling` catheter fastened alongside the
insertion tool as described below in the section entitled Binding
of Lines and Cables Alongside the Stay Insertion Tool is used to
deliver heated air. Thus, coating each stay with cyanoacrylate
cement mixed with superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder and radiographic contrast,
even without warming the ductus for a few seconds before, much less
twenty seconds following insertion, the risk of escape into the
bloodstream is small enough that stays can be used in arteries.
Less desirable as a precaution against penetration into the lumen
is the use of intraductal ultrasound.
[4421] While allowing penetration into the lumen of even the tip of
a stay to be observed, to use this endoluminal technique would
negate a principle advantage in the use of stays over miniballs,
which is precisely the avoidance of the lumen entirely. Whether
encapsulated within a layer or layers of medication, stent-stays
for use with a stent-jacket are, by definition, ferromagnetic,
whereas stays used as mechanical buttresses to support a collapsed
or constricted ductus need not be ferromagnetic. Stays used to
deliver medication may consist solely of medication but
nevertheless lend mechanical support until absorbed. Stays can
serve irradiative, medicative, and mechanical requirements in any
combination, and different types of stays may suit different
segments of one and the same ductus.
[4422] Where the wall of the ductus has become weakened, the
nonimpactive placement and wider expanse of stent-stays makes these
preferable to the ballistic placement of miniballs, which could
perforate when discharged or pull through after placement. Due to a
preliminary ablation or atherectomy or erosion of the arterial wall
as the result of remodelling, weakening will be common. In vessels
wherein the loss of a miniball, however designed against and
improbable, would create a delay in completion of the procedure,
portend an interval to the development of collateral circulation
that is unacceptable, or would otherwise represent a complication
that was simply inadmissible, stent-stays can be used.
[4423] Since incisive entry is necessary to place the stent-jacket
anyway, the ability to insert the intraductal implants through the
same incision and do away with the need for a transluminal
component is attractive, and the more so when a preliminary
angioplasty is judged unnecessary. Directly related to the
elimination of a transluminal component is the fact that when
skillfully inserted, stays do not puncture the intima or lining of
the ductus treated, thus not weakening the ductus wall and
rendering moot questions concerning the risks of ischemia,
thromogenesis, and intimal infection.
[4424] Further, the stay insertion tool described below in the
section below entitled Stay Insertion Tools applies a tissue
sealant to the stay as it is ejected through the adventitia,
reducing the risk of a intraluminal separation within or
delamination from the internal tunic of the lumen leaving it
without retraction in an outward radial direction. Whereas
miniballs are spherical, stays can be relatively thin and large in
extent longitudinally and circumferentially, that is, in facing
surface area. For this reason, more expansive stays are
considerably more resistant to pull-through than are miniballs,
making these usable in tissue that is too malacotic for ballistic
implantation.
[4425] This expansiveness is also useful for replacing high density
implantation effected by means of a positional control system,
especially when the luminal wall might become so weakened as to
aneuryse, although this is averted when the stent-jacket is placed
prior to ballistic implantation. Stays can be absorbable whether
consisting purely of medication or medication coating an
irradiating seed; however, where the implants are nonmagnetic,
ballistic implantation can achieve extensive longitudinal coverage
in much less time. Regardless of whether the ductal intraparietal
implants are for use with a magnetic stent-jacket, ballistic
placement can be accomplished more quickly.
[4426] Once an arcuate stay-shaped core has been produced such as
by pouring the liquid medication into a mold to dry, stays that
consist entirely of medication or medication in successive
investment of subjacent layers of medication can be produced by the
same methods stated for the making of medication miniballs below,
which include pan tumble coating, centrifugal extrusion,
vibrational nozzle technique, and spray-drying. Similarly, a
stent-stay may consist of a radiation source seed core and
investing medication. Thus, the core of a stent-stay can be an
absorbable or nonabsorbable polymer, a drug, or a radiation
seed.
[4427] To minimize the risk of penetrating the lumen, stays are
never to be used except 1. In sufficiently thick-walled ductus, 2.
Unless insertion is constantly monitored for endothelial puncture
with endoluminal endoscopy or endoluminal ultrasonography
(intraductal untrasonography (IVUS), ultrasound probe sonography;
ultrasound catheter probe-assisted endosonography; catheter probe
assisted endoluminal ultrasonography), and 3. The stays are highly
visible, whether with the aid of orally administered pronase
(Sakai, N., Tatsuta, M. Iishi, H. and Nakaizumi, A. 2003.
"Pre-medication with Pronase Reduces Artefacts During Endoscopic
Ultrasonography," Alimentary Pharmacology & Therapeutics 18 (3)
327-332).
[4428] In some instances, plastic stays, coated with tantalum for
high radiopacity and usually phosphorylcholine to reduce tissue
reaction can maintain the patency of a ductus without the need for
a stent-jacket. With conditions unpredictable as to the eventuality
much less the time of subsidence, the stays employed can still
contain a ferromagnetic disk to allow the application of a
stent-jacket at a later date if necessary; otherwise, both magnetic
disk and stent-jacket are optional; however, stays should always be
radiopaque, and the inclusion of ferromagnetic material is
preferred as expediting recovery if necessary. With predictable
subsidence, stays can be absorbable, partially absorbable, or
self-shrinking, and can release medication associated with the
process of dissolution, as described below.
[4429] The applications of stays can be completely unrelated to the
use of magnet traction to retract a ductus wall outwards towards a
stent-jacket or magnet-jacket (magnet-wrap). The stay insertion
tool as described below in the section entitled Stay Insertion
Tools can also be used to introduce stays that consist entirely of
medication or radiation seeds in the form of stays into the wall of
a ductus. Stays used to localize medication or radiation within the
lumen wall can be absorbable, in which case, the same materials
used in absorbable suture and most tissue engineering scaffolding
are used, as described below. The stays are curved for
concentricity to the resting circumference of the ductus and,
depending upon the condition to be treated, variable in
proportional length to the diameter of the ductus to be implanted,
but seldom longer than the radius of the ductus from the lumen
center to the surface, or half of the outer diameter.
[4430] Since the materials used for the various types of stays tend
to be inelastic, when the percent increase in diameter of the
ductus requires, the ends of the stays are turned back outwards or
everted in order to preclude a puncturing through the internal
layers of the wall by the tips of the stay when the ductus expands.
Once an antecedent angioplasty, if any, has been completed, stay
insertion is without transluminal component, access accomplished by
local exposure. The external surface of the adventitia in contact
with the internal surface of the stent-jacket, and the implanted
stay closely subjacent thereto, the stay is unable to move in a
manner as would cut the media.
[4431] The camber of the stay is such that upon insertion along a
tangent normal or perpendicular to the axis of the ductus with the
convex side directed outwardly (radially), the stay remains
substantially concentric to the ductus, that is, parallel to the
ductus longitudinally and concentric to it perpendicularly, with
bowing contrary to such bodily displacement slight at most.
Substantial concentricity with the circumference of the ductus
causes the stay to move with the rest of the lumen wall preventing
its ends from incising the wall medially toward the lumen. Once
implanted, the risk for escape into the surrounding body cavity or
tissue is small, and once the stent-jacket has been applied, stays
are prevented by magnetic attraction from escaping into the lumen
and by physical obstruction by the stent-jacket from perforating
outward.
[4432] While the risk for a stay to drop away from the ductus, much
less become lost to view in the usually moist environment strongly
adherent for it is slight to nonexistent, the stay insertion tools
described below in the section entitled Stay Insertion Tools also
serve as hand-held electromagnets that would allow a dropped stay
to be recovered. Situated outside the lumen, no implant described
herein should ever be heated by an alternating current-powered
hand-held electromagnet as a noninvasive means for accomplishing
followup thermal angioplasty to treat restenosis. To do so would
burn extraluminal tissue.
[4433] Shorter stays are meant to achieve lumen patency by
attraction to the surrounding stent-jacket, while, depending upon
the condition to be treated, longer stays without an embedded
ferromagnetic disk at the center can be used to exert a patenting
effect without the need for a circumvascular stent-jacket. To the
extent that it does not result in a degree of flexibility that
allows deflective bending during the making of the adventitial or
fibrosal entry incision, the stays are made thinner toward the ends
to be flexible for compliance with the contractile action of the
ductus. The stays are inserted through the external surface of the
ductus to undercut the adventitia with a special insertion tool
described below in the section entitled Stay Insertion Tools and
are can be cold process plasma vapor deposition or sputter-coated
with tantalum, for example, for increased radiopacity.
[4434] For improved tissue acceptance, a coating of
phosphorylcholine or a polymeric blend thereof (see Lewis, A. L.,
Vick, T. A., Collias, A. C. M., Hughes, L. G., Palmer, R. R.,
Leppard, S. W., Furze, J. D., Taylor, A. S., and Stratford, P. W.
2001. "Phosphorylcholine-based Polymer Coatings for Stent Drug
Delivery," Journal of Materials Science: Materials in Medicine
12(10-12):865-870(6); Jones, S. A., Stratford, P. W., and Rimmer,
S., assignors to Biocompatibles Limited, Uxbridge, England 2000.
"Polymeric Blends with Zwitterionic Groups," U.S. Pat. No.
6,150,432) is then applied to the tantalum and can also be added to
the concentrated sugar solution used to bond and position the stays
together in strips.
[4435] The use of a specific formulation of phosphorylcholine is
secondary to the requirement for noninterference with the tackiness
essential to seal the adventitia entry slit or for the cohesion of
the stays within a strip for insertion in the stay insertion tool
(addressed below). Polyester affords affords arcuate shape-holding
ability consistent with flexibility, a low coefficient of friction,
implantability without concern for substituent toxicity in the
event of degradation, and tantalum coatability. Other polymers
usable are polyethylene terephtalate with or without glass fiber
and polystyrene.
[4436] If, as determined by the empirical probe-rod test described
in the section below entitled In Situ Test on Extraluminal Approach
for Intra- or Inter-laminar Separation (Delamination), the
susceptibility of a lamina, such as the adventitia to delaminate or
separate interlaminarly (radially fail, dissect) over time is
ascertained to occur at a tractive force that is less than that to
be exerted by the stent-jacket, then the stay is inserted to a
greater depth, that is, into the media, which is accomplished by
applying slightly greater downward force upon the insertion tool,
the action more clearly viewable with the aid of an attached
endoscope, for example, as described below.
[4437] Due to the continuous replacement of connective tissue, the
adventitial or medial insertion incision adhesive-sealant
automatically ejected with each stay by the insertion tool (of
which little need reach the underside of the stay in any event)
will not afford long term adhesion as would prevent adventitial or
external elastic lamina delamination, for example, over more than
several months (although the rate may be retardable--see Han, M.,
Wen, J. K., and Zhou, X. X. 2004 "Effect of Yiqi Huoxue Huayu
Recipe on Vascular Collagen Turnover and Relevant Gene Expression,"
[in Chinese with abstract in English at Pubmed], Zhongguo Zhong Xi
Yi Jie He Za Zhi [Chinese Journal of Integrated Traditional and
Western Medicine] 24(2):136-139).
[4438] The surface of the stay is therefore grooved or ribbed and
given a surface texture to encourage the gradual replacement of the
adhesive with tissue that will infiltrate and adhere to its
surface. Since the stent-jacket is chosen for the minimum effective
attractive force, the choice of a stent-jacket having magnets that
are so weak as to avert delamination (intralaminar separation) will
have been precluded. Shown in FIG. 86, stays are a little wider at
the center for increased surface area and thus more forceful
retraction with reduced tendency for pull-through or becoming
displaced. Upon ejection, each stay is maintained in rectilinear
position to assure linear feed through the insertion tool ejection
slot. Stays typically measure 2-3 millimeters in width by 4-5
millimeters in length, with rounded or blunted corners and honed
edges at the ends.
[4439] Symmetrical, the rear edge is configured for engagement by
the v-notch at the driving forward edge of the highly flexible
spring steel or polyester-ferromagnetic steel laminate insertion
tool plunger-blade (addressed below). In FIG. 93, soft iron cores
230 embedded at the center of each stay 231 by having been included
in the mold are chemically isolated. The stays flexible except at
the center but incapable of rotation as would lacerate the tissue
surrounding the edges and tips, surface texture or embossing can be
molded into the stay to promote tissue infiltration for stronger
positional fixedness once implanted, it. Texturing the surface also
allows better temporary adhesion of the sugar used as a bonding
agent between adjacent stays to fasten these together into a strip
in which the position of each is stable for ejection.
[4440] As shown in FIGS. 92 and 93, stays are separably connected
into strips for sequential ejection similarly to staples. The floor
of the ejection slot and surrounding walls of the stay magazine
serving to substantially position the stays for sequential
ejection, the stays are weakly tacked face to face to allow
insertion in the magazine as a clip of several at a time and to
more exactly align and separate the stays 231, which bowed and
thinner toward the ends than at the center must nevertheless be
stacked at the correct angle for sequential concentric implantation
and engagement by ejection tongue or plunger-blade 247 along the
rear edge. The stays are tacked together into a unified strip so
that each can be separated from the those remaining above it in a
manner analogous to the queued dispensing from a strip of office
staples.
[4441] A sterile concentrated solution of sugar is brushed along
either side of the stays stacked in the magazine so that
capillarity draws the solution into the recesses between adjacent
stays formed by the thinner end portions. On drying, the strips are
sealed in sterile packages with inflexible sides as prevent
breaking the strips. Once conveniently placed within the insertion
tool magazine in a strip rather than individually, the stays are
correctly positioned, breaking of the sugar bonds by the downward
compressive force of the magazine spring no longer mattering. For
the number of stays in a strip, the residue that accumulates at the
bottom of the stay insertion tool magazine is not sufficient to jam
the tool.
[4442] Almost all of the sugar that accumulates at the bottom of
the stay insertion tool magazine is pushed out of the ejection slot
by the next stay upon ejection, is swept to either side of the
ductus entry incision, and falls away into the body cavity wherein
it is harmless, trace amounts entering the ductus being likewise
harmless. The nuisance of inserting each individually into the
insertion tool magazine notwithstanding, unused stays are best
sterilized with ethylene oxide gas, peroxide plasma, or gamma
radiation. It is obvious that the attracter-attractant relation
could be reversed so that the soft iron or other ferromagnetic
disks within the stays could be magnetized axially, in which case
encapsulated soft iron or other nonmagnetized ferromagnetic
material would be mounted in place of small bar magnets about the
surface of the stentjacket.
[4443] XV4. Partially and Completely Absorbed Stays
[4444] Stent-stays that would accommodate a detumescing (resolving,
subsiding) ductus by correspondingly shrinking without changing in
conformation are discounted as demanding substantial constancy in
retractive effect despite change in the mechanical properties of
the ductus as the ductus continued to decrease in size, which would
present equally intractable problems as contracting stent-jacket
base-tubes. Substantially the same alterations in conformation can
be obtained through the use of partially absorbed stays.
[4445] Stays can interleave material used for absorbable suture or
staples (see Ravo, B., Rosales, C., Serino, F., and Castagneto, M.
1991. "The Use of Absorbable Staples for Construction of a Bladder
Tube," Surgery, Gynecology, and Obstetrics 173(1):29-32) with the
agents of their dissolution, so that catgut (collagen) is
interleaved with a proteolytic enzyme or a synthetic with a water
releasing hydrogel, and completely or partially absorbed stays for
maintaining patency during the course of a temporary or subsiding
condition can embed or interleave medication that is liberated by
absorption.
[4446] The cyanoacrylate cement, such as ethyl 2-cyanoacrylate
tissue adhesive or hydrogel (addressed above), used to bond plies
of an absorbable or partially absorbable stay can be absorbable,
release medication, or both. Anticlotting medication administered,
it is feasible to initiate the absorption of a stay (or miniball,
but not a stent-jacket expansion insert, which lies out of
effective reach), its release of medication, or both in the
bloodstream by thermal angioplasty with a barrel-assembly or
thermal balloon catheter. Absorbable inserts implantable by means
of the stay insertion tool can consist purely of medication
compacted with or without an excipient base, medication applied to
an absorbable base-stay, or absorbable material and medication
particulates intermixed and compacted into a tablet of insertable
shape.
[4447] When not collaterally serving a lumen patenting or stenting
function, such implants can be shorter than the shape of a
patenting stay as described above. When the material of the tablet
otherwise lacks sufficient hardness to provide a honed leading edge
of penetration strength, a rim surround of absorbable material is
used to provide this strength. Medicating and/or irradiating stays
can be produced with the medication coated onto the stay, which is
made of the same materials as specified in the section above
entitled Stent-jacket Expansion Insert Materials Having Relatively
Short Breakdown Times that are used to make absorbable suture for
more immediate release whether timed, or the medication can be
interleaved with or interspersed through the absorbable material
for more extensive timed release.
[4448] XV5. Circumstances Dissuading or Recommending the Use of
Stays
[4449] Properly applied and inserted, stays avoid the lumen
entirely. Stays are inserted into the wall of the ductus from
outside the ductus so that the lumen is avoided, and can consist of
or include medication, an irradiating seed, and/or ferromagnetic
material for the radially outward retraction of the ductus wall by
a stent-jacket. Since neither stays nor the placement of stays
require entry into the lumen, stays are preferable when contact
with the interior surface of the wall surrounding the lumen would
best be avoided. The use of stays also eliminates the need to pass
through tortuous stretches, which can be stented with a chain-stent
(articulated stent-jacket) with segments as short as necessary.
[4450] Stays are individually inserted by hand and therefore take
longer to apply than miniballs, which even without the aid of
automatic apparatus can be introduced at a faster rate; however,
stays avoid the risk of perforation and the need to preposition the
stent-jacket or a specially devised stent-jacket to avert a rebound
into the lumen due to having set the miniball discharge exit
velocity too high. While stays can be inserted with a force
determined on the basis of testing the tissue to be implanted, to
do so is rarely essential. As addressed below in the sections
entitled Stay Insertion Tools and Testing and Tests, this means
that testing and the incorporation of a calibrated thumb-shaft
return-spring screw adjustment in the stay insertion tool can be
discounted, resulting in significant savings in procedural time and
the cost of equipment.
[4451] Inserted one at a time, stays take more time than miniball
discharge. Successive miniballs can differ in composition. By
sequencing successive shots in the magazine or gravity line feed
and not deviating from this during placement, miniballs that differ
in composition, mass, and diameter, to match conditions shown by
imaging need not slow down discharge. Similarly, to treat a ductus
that exhibits frequent differencesin pathology and strength, each
stay can differ in any or all attributes. When perivascular fat, an
attachment, or an adhesion can be resected expeditiously without
significant injury to allow insertion, stays can be used. When even
small amounts of such tissue should not be resected, stays are
avoided.
[4452] The relative mid- and post-procedural disruption in function
and the term of that disruption likely to result from external
approach is weighed against the disruption likely to result from
internal approach. Short segments are generally treated more
conveniently with stays, which have the additional advantage of
single entry with the lumen avoided altogether. While stays and
stent-jackets are both inserted percutaneously through the same
incision, stays require unobstructed access to the outer
adventitial or fibrosal surface whereas stent-jackets may
specifically include such tissue as essential for normal
function.
[4453] As addressed above in the section entitled Field of the
Invention, a small amount of perivascular fat supports normal
intravascular function nutritive, respiratory or blood gas
exchange, and endothelial, whereas an excessive amount results in
malfunction and disease. Prospective benefit relative to risk is
the deciding basis, attachments such as omental or mesenteric are
seldom so vulnerable that the small interruptions needed to allow
stays to be inserted would prove problematic. Stays can consist
entirely of or be coated with medication and/or other therapeutic
substances, and can be absorbable or nonabsorbable. Adjacent stays
can be the same in size, shape, and composition or differ in these
regards. Larger stays can incorporate radioactive seeds, telemetric
sensors, or resonant circuits, for example (see, for example,
Ferguson, J. E. and Redish, A. D. 2011, Op cit.).
[4454] Since stays are inserted subadventitially from outside the
artery as to avoid the lumen, the serum concentration of platelet
blockade if any can be reduced. Thus, in instances where the
prospect is greater that bypass grafting will prove necessary,
stays not only reduce potential bleeding during a following graft
procedure, but depending upon the position of the treatment site or
sites, may be insertable through an incision placed to allow for an
endoscopic bypass procedure should the need therefor become
apparent. The use of stays thus avoids penetration through the
intima from inside the lumen, leaves no internal wounds as might
thrombose or become irritated or infected, allowing implants to
escape into the lumen, and is independent of transluminal entry to
perfom an angioplasty or for any other purpose.
[4455] This is especially advantageous in the treatment of blood
vessels, allowing a reduction in the dose or elimination of a
platelet blockade in arteries, for example, and for use in the
ureters and gastrointestinal tract, which are affected by pathology
more associated with the inward or adluminal than the outer tunic
and where endoluminal stents invariably become clogged requiring
periodic replacement. Stays are preferable when the lumen contents
are infectious or septic so that the tiny perforations produced
during ballistic implantation would expedite the spread of
infection. Alternatively, miniballs are implanted with the
stent-jacket, double-wedge lined stent-jacket, sheld-jacket, or
impasse-jacket within an absorbable shield-jacket placed to prevent
perforations.
[4456] The inner surface of jackets used thus are wetted with an
antiseptic. To protect against the spread of infection through
leakage from an accidental perforation, stays are coated with an
antibiotic. In the lower gut, for example, the systemic antibiotic
administered can be lower in dose and less likely to destroy
intestinal flaura essential for the normal clotting of blood and
digestion. Implanted without entry into the lumen, stays are
preferable for `direct stenting` without site preparation in the
form of an ablation or angioplasty of the diseased tissue within
the lumen. Since stays have circumferential extension, these are
easier to overlay with the magnets mounted to the base-tube than
are miniballs.
[4457] When magnet overlay alignment is problematic, an
intrinsically magnetized stent-jacket is used. Stays afford a
factor of immediate accessibility to the treatment site. Simply
stated, this means that stays are better suited to ductus readily
accessible from outside the adventitia, whereas miniballs are
better suited to ductus readily accessed from within the lumen.
Tactile feedback (touch) and a direct view through an endoscope
attached alongside the stay insertion tool by means of the clips
addressed below in the section entitled Binding of Lines and Cables
Alongside the Stay Insertion Tool stays eliminate the need, as in
the discharge of miniballs, to adjust for any delay following
triggering for the miniball to exit while the ductus wall continues
to move.
[4458] This makes it easier for the operator to anticipate the
moments for insertion Stays are suited to use in superficial ductus
where little dissection is required to achieve insertion, whereas
miniballs can be delivered to any location. Stays must be
disproportionately thick in relation to the thickness of the ductus
wall to increase the thickness thereof to any physiologically
significant extent. Significant short-term swelling if any
following the infixion of miniballs or stays warrants coating the
implants with a steroid drug, for example. When the ductus is
superficial but plunges, procedural brevity is served by using
miniballs throughout, unless the segment accessible at the surface
is malacotic as to recommend the use of wide stays.
[4459] Obstruction of the gastroduodenal or bile duct using stays
to accomplish the stenting involves a relatively minor surgical
procedure compared to a double gastric and biliary bypass
operation, and while more invasive than the endoscopic placement of
an endoluminal stent; an extraluminal stent is less likely to clog
(see, for example, The Merck Manual of Diagnosis and Therapy, 18th
edition, 2006, Section 2, Gastrointestinal Disorders, "Pancreatic
Cancer," page 179). Furthermore and critically, once placed, the
extraluminal stent is in position to attract magnetically targeted
clog-dissolution, drug, and/or radiation carrier particles that
will draw the agent up against and into the lumen wall and not to
itself as a diversionary obstruction to such contact.
[4460] Stays are equally applicable to lumina such as the trachea,
which presents a structured anatomy, and those such as the
esophagus and arteries, which are relatively undifferentiated.
Inserted from outside the adventitia, stays do not require the
preparatory removal of calcified plaque lining an artery or oxalate
salt accretions lining a ureter, for example, in order to allow the
underlying lumen wall to be implanted within. While more pronounced
mineral prominences should be removed, the complete removal of such
deposits can prove counterproductive; hardening of the cap over an
atheromatous plaque, for example, can actually serve to reduce its
vulnerability to rupture.
[4461] A less thorough removal of calcified plaque also lowers the
risk for a perforation that a burr can cause. Unlike miniballs used
in the arterial tree, stays need not be coated with
antithrombogenic, intimal hyperplasia-reducing, or
anti-inflammatory medication. Should implants be needed that are to
be temporary but not completely absorbable, as occurs, for example,
in the placing of irradiating seed-cored stays, an advantage is
gained once again at the time the stays must be recovered. When
intraductal ultrasound, for example, reveals that remodelling has
reduced the media so that even with the use of a tumefacient as
addressed above in the section entitled Ductus Wall Tumefacients
the wall remains too thin to implant ballistically, stays may still
be able to undercut the adventitia and allow the placement of an
extraluminal stent.
[4462] The conformation of stays is more efficient from the
standpoint of providing for a higher flux density through the
magnetic circuit allowing the use lower field strengths. Where
magnetic stent circuit leakage flux (flux leakage, flux spillover)
is essential to attract drug carrier particles from the passing
blood, stays can project greater tractive force and are generally
preferable to miniballs. The deliberate inclusion of pits or rust
in miniballs used to both stent and attract magnetic drug carrier
particles thereby to produce leakage flux is considered evident to
those skilled in magnetic circuitry. In such use, the strength of
the ductus wall must be confirmed as capable of sustaining the
tractive force used for stenting before drug attraction as an
attendant or ancillary use can be considered.
[4463] Although stays and miniballs may be equally applicable in
certain circumstances, the provision of two different kinds of
intramural implants, either of which can consist of or include
medication, numerous other therapeutic substances, or radiation as
well as complement a stent-jacket makes possible the choice of one
or the other for responding to different anatomical and medical
conditions. The overall system described herein similarly provides
alternative approaches, methods, and apparatus. In muscular
arteries, tumefacients that work by contracting the smooth muscle
of the lumen wall will also reduce the luminal diameter.
[4464] Radially outward retraction of the lumen wall achieved by
attracting subadventitially or perimedially placed implants is more
effective when the type disease or previous ablation of diseased
tissue lining the lumen makes postprocedural obstruction by
adluminal swelling less likely. In instances where contact with the
intima with a transluminal device is likely to promote swelling,
stays may be better suited to stenting without a preliminary
angioplasty, atherectomy, or ablation of the lumen lining and
therewith, complete avoidance of a need to enter the lumen. For
example, stays can be used where the removal of less significantly
protrusive calcified plaque is contraindicated.
[4465] However, an accretion, plaque, or lesion will then have been
left to protrude into the lumen, which may recommend the use of a
stent-jacket slightly larger in diameter. This will distend the
ductus to a degree slightly larger than its resting or diastolic
diameter, interfering with smooth muscle function over the stented
segment. However, wide stays, especially if coated with
cyanoacrylate cement, for example, are far less susceptible to
pull-through or delamination than are miniballs. This may represent
a factor that would affect the diameter of a muzzle-head or radial
projection catheter used in the segment to be treated but will
rarely if ever affect the use of stays.
[4466] Due to the need to minimize the disruption of plaque by the
antegrade rise in blood pressure caused by obstruction of the lumen
and contact with the muzzle-head, a thermal angioplasty or an
atherectomy is usually considered prerequisite to the transluminal
(ballistic) implantation of spherules, or miniballs, within the
lumen wall. However, angioplasty-capable barrel-assemblies
incorporate heat-windows and radial projection units to accomplish
this without a preparatory conventional balloon angioplasty. A
combination-form angioplasty-capable barrel-assembly or radial
projection catheter can also accommodate an excimer laser or
rotatory burr, for example; however, the constraint on diameter for
off-pump use is severe.
[4467] For introducing medication into the luminal wall, even in a
coronary artery off-pump, the endoluminal barrel-assembly is
superior, because a secondary entry to access the outside of the
ductus is unnecessary, movement along the vessel is substantially
unimpeded, and insertion whether by injection tool-insert or
miniballs is quick. Where stenting is contemplated, a second entry
to allow access from outside the vessel is still necessary.
Reciprocally, in avoiding the lumen altogether, stays can pose a
distinct advantage. When a magnetic stent is to be applied without
preliminary therapy, angioplasty, or atherectomy, endoluminal
access can be avoided entirely.
[4468] However, inserted from outside an off-pump coronary artery,
stays do not move with the substrate vessel with sufficient
stability as would a muzzle-head within the lumen. For this reason,
the use of stays in coronary arteries is done on-pump. Stays are
best used on other type ductus following open exposure where even a
keyhole incision is not needed to gain access. The nose of a
barrel-assembly for use in the bloodstream contains an electrical
heat-window to thermoplasty the luminal wall in advance of the exit
ports to destroy any debris that might pass downstream. For this
reason, unless stays do not allow dispensing with any transluminal
part of the procedure, a significant advantage stays afford is
lost.
[4469] By contrast, as transluminal, the use of miniballs in
arteries is provided with means to avert cerebral and cardiac
vascular accidents. In arteries, stays are suitable where there is
less risk of plaque ruptures so that angioplasty can be omitted;
otherwise the forces applied to the ductus wall in inserting a stay
could dislodge fragile matter. However, especially with respect to
the carotids and coronaries arteries, where a release of embolizing
debris during a balloon angioplasty could prove catastophic, a
recent trend has been to avoid an angioplasty even with the use of
a forward deployed or run-ahead embolic filter (references appear
in the section below entitled Thermal ablation or angioplasty-
(Lumen Wall Priming Searing- or Cautery-capable
Barrel-assemblies).
[4470] Since the stent-jacket can be placed before discharge is
initiated, the use of stays is not compelled due to proximity to a
nerve, ganglion, or other critical structure. As addressed below in
the section entitled Concept of the Extraluminal Stent and the
Means for Its Placement), an angioplasty-capable barrel-assembly
does include a trap-filter (embolic filter, filter-trap). Inserted
from the body surface and through the adventitia, stays can often
be introduced through the same relatively small incision as a
smaller stent-jacket. Stays are most easily used in an open
surgical field exposed for some collateral purpose. Then the
operator can increment the insertion tool along the ductus at right
angles.
[4471] Entering through a short incision at the body surface, a
stay insertion tool with pivot head, addressed below in the section
entitled Insertion Tool with Laterally Pivoting Foot-joint
(End-pivot, Tilt-end, Foot-pivot), can maintain a right angle
relation to the ductus over a short segment of the ductus at
shallow depths. Otherwise, unless the length of the stent is small
or the ductus can be pulled pulled up to and sideways beneath the
the entry incision, stent-stays necessitate an incision longer than
that required just to place the stent-jacket. This limitation does
not apply to medication and/or radiation stays, which are made
wider to contain a larger dose.
[4472] Depending upon the length of the entry incision and need for
dissection, ballistic implantation can reduce overall trauma.
Nevertheless, the use of stent-stays allows the transluminal
component in the placement of an extraluminal stent to be
eliminated, and therewith, the risks associated with ischemia,
stretching injury, the disruption of plaque, and so on. These
considerations pertain to arteries as to demand accommodation in
the design of the apparatus to be described.
[4473] However, since absorbable implants for delivering medication
and/or radiation locally within the wall of the ductus (see, for
example, Waksman, R., Laird, J. R., Jurkovitz, C. T., Lansky, A.
J., Gerrits, F., Kosinski, A. S., Murrah, N., and Weintraub, W. S.
2001. "Intraductal Radiation Therapy after Balloon Angioplasty of
Narrowed Femoropopliteal Arteries to Prevent Restenosis: Results of
the PARIS Feasibility Clinical Trial," Journal of Vascular and
Interventional Radiology 12(8):915-921) do not involve the use of a
stent-jacket, ballistic implantation is superior to absorbable
stays for this purpose, stays necessitating access to the exterior
of the ductus through incisions.
[4474] For arteries invested within muscle, this poses a risk of
incising, possibly even transecting the ductus. Medication stays
are therefore reserved for use in an open. surgical field where the
site has already been exposed. Even disregarding the time needed to
access each target spot or point to be implanted, ballistic
implantation is accomplished much more quickly. Situation in the
lumen of an ablation or an ablation and angioplasty-capable
barrel-assembly also allows the application of numerous procedures
that cannot be used from outside the ductus, such as endoscopy,
aspiration, the delivery of heat or cold by different means, brush
cytology, and so on, as addressed below in the section entitled
Ablation and Ablation and Angioplasty-capable
Barrel-assemblies.
[4475] These functions can often be augmented through the use of a
combination-form barrel-assembly, as addressed below in the section
entitled Combination form Barrel-assemblies: Barrel-assemblies
which Accommodate or Incorporate Means for Ablation, Thrombectomy,
Atherectomy, Atherotomy, and/or Endoscopy, which allows devices
such as an aspiration line, endoscope, laser, or atherectomy cutter
to be inserted through the central canal to the nose of the
edge-discharge muzzle-head. Use of the inserted device or devices
does not affect the simultaneous use of other implements, such as
radial projection unit tool-inserts, located about the periphery of
the muzzle-head.
[4476] The larger aspiration line that the central canal will
accommodate expedites the preliminary removal from a ductus of any
debris that could interfere with treatment, for example. Another
advantage of ballistic implantation is that the ductus need not be
placed under torsion or twisted around to face the operator, which
may necessitate more dissection than is necessary merely to place a
slotted stent-jacket. Depending upon its length and the depth of
the treatment site, a stent-jacket can usually be introduced
through an opening and maneuvered into position about the ductus
through one or two small incisions held open by means of a
miniature retractor, such as one similar to an omni-bearing
retractor used in abdominal surgery.
[4477] Stays, however, must be placed with the insertion tool in
substantially perpendicular relation to the ductus, which generally
necessitates incisions somewhat longer than is needed merely to
place the stent-jacket. An analogous situation in that the approach
to the treatment site must be normal is seen in the conventional
procedure for placing prosthetic tracheal rings about the collapsed
trachea of a small dog. This results in extensive trauma that
alternative treatments to be described avoid. Prior art stents that
are sutured to the outer surface of a ductus may appear similar to
a stent-jacket, but these do not comply in both flexion and
intrinsic motility such as peristaltic or tonic while affording
circumvascular support. Moreover, the suture employed will usually
course into the lumen, and to introduce such extraluminal stents
demands open exposure.
[4478] By contrast, the stents to be described are entirely
extraluminal, and compliant, allow placement of the outer component
or stent-jacket through a relatively small opening. These stents
differ fundamentally from previous stents in being neither entirely
endoluminal nor circumvascular. To place such stents requires some
additional procedural time and trauma; however, as will be
explained, the advantages of such stents, physiological compliance,
more than compensate for these detractions. The stay insertion tool
is designed to prevent the entry of a stay into the lumen, and is
so weighted and configured that the operator must intentionally
apply downward force in excess of the passive weight of the tool on
the ductus to obtain a greater depth of insertion.
[4479] With stent-stays, which usually permanent, have a
ferromagnetic core for use with a magnetic stent-jacket, both the
stays and the stent-jacket are introduced into the body through the
same small incision that is used to pre-test the tissue at the
treatment site, as described below in the section entitled In Situ
Test upon Extraluminal Approach for Intra- or Inter-laminar
Separation (Delamination). Abluminal, sterile stays should never
enter the lumen. If such a risk is suspected due to later
infection, a systemically distributed antibiotic is administered.
Applied at or near to the treatment site, stays allow a ductus with
problematically pronounced intrinsic autonomic motility to be
visually gauged in rate and excursion and implanted by hand.
[4480] Lumina inaccessible to a barrel-assembly, such as in the
common bile duct and coronary arteries may be suitable for stays,
medication to increase ductus wall treatment, if necessary,
addressed above in the section entitled Attainment of Implantable
Intramural Thickness. When a barrel-assembly would meet with
interference and the segment sought to be treated and/or stented is
accessible without undue trauma from without, stays can provide a
superior solution. Not entering the lumen, if the pulse interferes
with insertion, stays can allow an artery to be clamped only so
long as it is necessary to insert the stay. To similarly suppress
an interfering pulse with a barrel-assembly, however, does not
require clamping.
[4481] Instead, the artery is temporarily cuffed by preplacing the
stent-jacket and initially tightening the hook and loop secured
belt-straps during discharge so that the stent-jacket cannot comply
with the pulse by expansion at the side-slit or side-slot. Once the
implants are in place, the belt-straps are loosened to allow
compliance with the pulse. The stent-jacket used is usually of the
double-wedge type as addressed above in the section entitled
Double-wedge Stent- and Shield-jacket Rebound-directing Linings.
Preplacement of a stent-jacket at the treatment site is
inapplicable to the use of stays. Extended circumferentially and
longitudinally, stays present far more surface area to the lamina
to either side.
[4482] This can be used to distribute and reduce the tractive force
per unit area, to present larger surfaces bonded to adjacent
layers, and the flatter profile will resist perforation by
pull-through more than would a spherule. Even though using
ballistic means a malacotic luminal wall can be prepared or primed
with a strengthening (hardening) agent such as a tissue cement
injected through a service-catheter of through a radial projection
unit tool-insert injection head, the stay is thus from the outset
and will remain more resistive to pull-through at once and over
time. The larger surface area of the stay allows more bonding agent
and superior adhesion through tissue infiltration of a textured
surface.
[4483] For example, when the wall of the ductus requires
reinforcement with a tissue bonding and hardening agent
(adhesive-hardener) and the type of lesion should not be subjected
to heat, the fact that stays can be coated with such an agent as
cyanoacrylate cement, which bonds quickly without the need for
heating allows stays to be applied to a wider diversity of lesion
types than does ballistic implantation. By contrast, coating
miniballs with cyanoacrylate cement, which is addressed below in
the section entitled Cyanoacrylate Injection Catheter is a process
secondary to ballistic implantation which adds time and tedium to
the procedure.
[4484] Ballistic implantation without the use of cyanoacrylate is
quick, likely to result in less injury should a miniball have to be
extracted, does not necessitate superjacent entry above each
miniball implant, and requires no incision at all when pure
medication miniballs, for example, which require no extraductal
stent-jacket are to be implanted. Whereas stay insertion, even with
an insertion tool that includes a flex-joint, requires access and
approach in the direction that is substantially normal
(perpendicular) to the insertion site, a stent-jacket can be
introduced through an incision that is smaller in length than the
stent-jacket itself. In an artery, ballistic discharge is normally
reserved for the diastoles when the vessel wall is relaxed
(undistended) and closer with less blood interposed, whereas the
insertion of stays, since it is accomplished from outside the
vessel, is usually reserved for the systoles when the distended
condition of the vessel makes insertion easiest.
[4485] An endoscope mounted alongside the stay insertion tool
allows viewing the expansion of the ductus. The section above
entitled Motional Stabilization of the Implant Insertion Site
addresses the means for dealing with problematically fast and/or
irregular smooth muscle action. Where it is believed that a
calcified cap actually serves a protective function, extraluminal,
unlike endoluminal stenting, allows plaque that does not occlude to
remain, and whereas the presence of calcified plaque may preclude
ballistic implantation, stays are inserted from outside the ductus.
The vulnerability of plaque appears to vary with the strength of
its roof as barrier separating the blood from the debris
within.
[4486] Thus, vulnerability or susceptibility to rupture seems to
increase in the order of no fibrous cap to thin and then thick
fibrous cap, and from caps with less to more extensive
calcification (Li, Z. Y., Howarth, S., Tang, T., Graves, M.,
U-King-Im, J., and Gillard, J. H. 2007. "Does Calcium Deposition
Play a Role in the Stability of Atheroma? Location May be the Key,"
Cerebrovascular Diseases 24(5):452-459). Unlike miniballs, which
can be quickly implanted in different directions about the lumen at
once, stays are manually implanted one at a time from outside the
ductus with the aid of a stay insertion tool as described below
entitled Stay Insertion Tools through a laparoscopic or keyhole
incision.
[4487] Using an automatic positional control system synchronized to
airgun discharge, implantation can be accomplished even more
quickly and accurately. When the site for treatment is more
extensive, this can make the operative time required a significant
consideration. A spherical surface such as that of a miniball or
the core in a stay, which is effectively a miniball embedded at the
center of a curved flange, is relatively inefficient as a magnetic
interface. However, the extension of the flange makes it possible
to disperse the ferromagnetic material in the stay, and whether
left in the form of a core or distributed, the ferromagnetic
material can be varied in surface geometry and oriented.
[4488] The more extensive area of the stay that is flush to the
layers of the tunic or lamina separating the stay from the magnet
distributes the tractive force, making the stay less susceptible
than miniballs to pull-through or delamination, and the front and
back surfaces of a stay allow more adhesive to be applied the
further to resist delamination. For a ductus weakened by disease
these factors can mean that stays would be effective where
miniballs would not. The area coated with adhesive, its subsequent
replacement by tissue, and adhesion of the tissue are adjusted by
controlling the depth and detailed configuration of the texture at
the surface, permanent stays deeply undercut in surface texture,
temporary stays, such as irradiating seeds, smooth at the
surface.
[4489] Temporary implants are retrieved with an electromagnet,
usually that a part of the insertion device (barrel-assembly or
stay insertion tool) that was used to place the implants or another
electromagnet. For quick extraction with the least tissue damage
upon retrieval, temporary stays, which are used apart from a
magnetic stent-jacket, are also made with the ferromagnetic
material concentrated at the tip which will be nearer to the probe
of the magnet used for extraction. Stays are well suited to
near-sided lesions in ductus of which the far side is secured by
connective tissue as not to require a partial, or slotted, rather
than a full stent-jacket.
[4490] The use of stays can be safely accomplished under
intraductal ultrasound, especially when each stay ejected is given
a coating of surgical cement, which action is performed
automatically by the stay insertion tool. Because a primary
advantage in using stays is the avoidance of the lumen entirely,
the concurrent use of a transluminal device such as for intraductal
ultrasound is reserved for more worrisome worksites, such as in the
coronary arteries. When used, the intraductal ultrasound head can
be made more manipulable by applying a disc of ferrous material to
its outside, which then allows it to be directed by means of a
hand-held electromagnet. When not a cyanoacrylate that attains
sufficient bond strength within seconds, the adhesive is then
warmed for about twenty seconds.
[4491] The risk of a stay entering the bloodstream is then very
slight, but were such to occur, the insertion tool providing means
for retracting and safely trapping a stay were it to enter the
lumen. In general, the use of stays avoids endoluminal entry and
the need for intimal perforation, indeed, avoids injury to the
endothelium not offered by any current means of treatment, which
the endoluminal approach of ballistic implantation does not. So
long as clamping can be avoided, circulation through an artery
continues without interruption. Except for an artery, however,
which is under pressure from within, and where stay insertion is on
the systoles, which are readily viewable with an endoscope mounted
alongside the stay insertion tool, circumstances can arise that
necessitate both extra- and endoluminal access.
[4492] A ductus wall that presents an intractable tendency to
collapse under the stay insertion tool despite the use of an
aspiration line clipped alongside the insertion tool to support it
may require the stationing of a conventional balloon or a
muzzle-head with circumferential radial projection units inside the
lumen at the level to be implanted. This is done by using the
turret-motor to position the side sweepers so that deploying these
will elevate the wall of the ductus in the arc desired. In such a
situation where entry is both endoluminal and extraductal, warming
to initiate setting of the adhesive can likewise be endoluminal
using the electromagnets or a line connected to the hot air outlet
of a vortex tube based `cold` air gun in the barrel-assembly, that
is, a cooling catheter running heated air, or extraductal, using
the same kind of line attached to a side of the insertion tool by
means of the spring clips.
[4493] Bringing the adhesive coating implants, whether stays or
miniballs, to an initial set by warming right after implantation
also reduces the risk of extraction by a passing magnet or a
prepositioned emergency recovery electromagnet. Adhesive is used
when tissue separation or migration are of greater concern than is
the more extensive injury that results when an implant must be
recovered. Greater ease of extraction is an advantage of miniballs.
The use of stays is indicated when, whether due to injury by the
antecedent angioplasty or pathology, the intima must or would best
be avoided, or where the limited time predicted for continued
adhesion of a clasp-wrap to the adventitia would fail to provide
extended effectiveness as required.
[4494] Stays can be used in combination with ballistic implantation
to treat only certain segments of a ductus for which ballistic
implantation is contraindicated. Under these circumstances, stays
afford a suitable expedient when only the accessible side requires
treatment or when the ductus is accessible for encirclement without
the need for excessive dissection or torsion to allow access to
sides in abutment with adjacent tissue. Stays are most useful where
the underside of the ductus is firmly attached and only the facing
side (arc) requires lifting support. In this situation, stays
positioned to support the `ceiling` will sometimes serve to
maintain patency without the need for a stent-jacket.
[4495] With or without a stent-jacket, stays should be avoided
where placement is near to the body surface without sufficient
surrounding soft tissue to absorb a strong accidental blow as in
the carotid artery, which could result in perforation into the
lumen. Securing a magnetic stent-jacket with belt-straps will
prevent stays or miniballs from entry into the bloodstream, making
miniballs, which have no piercing potential, preferable in this
context. As with ballistically implanted miniballs, while neodymium
lanthanoid magnets afford considerable energy products, retention
of a stent-jacket should not depend upon magnetic attraction alone
but be afforded sufficient circumference to reliably engage the
ductus mechanically through the resilience of the tube base
material with or without the aid of suture or hook and loop spandex
elastomer strapping end-ties.
[4496] Stays can be medicated or irradiative as discussed under the
section on miniball implants above. It is worth noting that
endoluminal stents pose a danger as the result of a direct blow.
While later infection that weakened the ductus wall might
conceivably lead to tunical delamination or the pull-through of
ductus-intramural implants so that these come to abut upon the
internal surface of the stent-jacket resulting in a loss in
patency, retention in place by the magnets--even though the
magnetic field strength is minimized to prevent delamination or
pull-through--should prevent the entry of the implants into the
lumen. Any significant loss in patency must assume that
anti-infection medication had not been administered when the
condition became apparent.
[4497] A similar ductus-intramural implant retention factor
pertains should the ductus wall weaken later due to disease. Stays
avoid the bloodstream as a source of contamination. Miniballs,
however, may become contaminated by pathogens picked up from
infected blood or other luminal contents during discharge, creating
an entry path into or innoculating the ductus wall. Since such
means are proposed for use with respect to tissue types as diverse
as blood vessels, ducts, the airway, and gastrointestinal tract,
such risk is widely variable, from the relatively sanitary
condition inside the bloodstream in health to the extreme burden of
bacteria in the colon.
[4498] Contamination through the endothelium can be protected
against by wetting miniballs with a suitable antiseptic or
antibiotic, although some of this as well as the pathogen is
`squeegeed` away as the miniball passes through the inner layers of
the ductus wall. Suction decompression of an ophthalmic segment
aneurysm and where the implants must not radiate heat to the
surrounding tissue, the use of magnetic resonance imaging will
require temporary removal of an extraluminal magnetic stent.
[4499] Amelioration through the administration of calcium channel
blockers notwithstanding (Gulmez, O., Atar, I., Ozin, B., Korkmaz,
M. E., Atar, A., Aydinalp, A., Yildirir, A., and Muderrisoglu, H.
2008. "The Effects of Prior Calcium Channel Blocker Therapy on
Creatine Kinase-MB Levels after Percutaneous Coronary
Interventions," Vascular Health and Risk Management
4(6):1417-1422), due to the potential consequences of myocardial or
cerebral ischemia if not abrupt closure and infarction as the
result of obstruction by the barrel-assembly of a coronary artery
(see, for example, Andron, M., Stables, R. H., Egred, M., Alahmar,
A. E., Shaw, M. A., Roberts, E., Albouaini, K., Grayson, A. D.,
Perry, R. A., and Palmer, N. D. 2008. "Impact of Periprocedural
Creatine Kinase-MB Isoenzyme Release on Long-term Mortality in
Contemporary Percutaneous Coronary Intervention," Journal of
Invasive Cardiology 2008 20(3):108-112; Javaid, A., Buch, A. N.,
Steinberg, D. H., Pinto Slottow, T., Roy, P., Pichard, A. D.,
Satler, L. F., Kent, K. M., Gevorkian, N., Xue, Z., Suddath, W. O.,
and Waksman, R. 2007. "Does Creatine Kinase-MB (CK-MB) Isoenzyme
Elevation Following Percutaneous Coronary Intervention with
Drug-eluting Stents Impact Late Clinical Outcome?," Catheterization
and Cardiovascular Interventions 70(6):826-831), or a carotid
artery respectively (see, for example, Nakahara, T., Sakamoto, S.,
Hamasaki, O., and Sakoda, K. 2003. "Double Wire Technique for
Intracranial Stent Navigation," Journal of Vascular and
Interventional Radiology 14(5):667-668; Qureshi, A. I., Suri, M.
F., Ali, Z., Kim, S. H., Lanzino, G., Fessler, R. D., Ringer, A.
J., Guterman, L. R., and Hopkins, L. N. 2002. "Carotid Angioplasty
and Stent Placement: A Prospective Analysis of Perioperative
Complications and Impact of Intravenously Administered Abciximab,"
Neurosurgery 50(3):466-475; Veeraswamy, R. K., Rubin, B. G.,
Sanchez, L. A., Curi, M. A., Geraghty, P. J., Parodi, J. C., and
Sicard, G. A. 2007. "Complications of Carotid Artery Stenting are
Largely Preventable: A Retrospective Error Analysis," Perspectives
in Vascular Surgery and Endovascular Therapy 19(4):403-408) or
vertebrobasilar artery (see, for example, Qureshi, A. I., Suri, M.
F., Khan, J., Fessler, R. D., Guterman, L. R., and Hopkins, L. N.
2000. "Abciximab as an Adjunct to High-risk Carotid or
Vertebrobasilar Angioplasty: Preliminary Experience," Neurosurgery
46(6):1316-1325; Rasmussen, P. A., Perl, J. 2nd, Barr, J. D.,
Markarian, G. Z., Katzan, I., Sila, C., Krieger, D., Furlan, A. J.,
and Masaryk, T. J. 2000. "Stent-assisted Angioplasty of
Intracranial Vertebrobasilar Atherosclerosis: An Initial
Experience," Journal of Neurosurgery 92(5):771-778), the
application of an extraluminal stent to these vessels may recommend
the use of stays rather than miniballs.
[4500] However, when stays are used, avoidance of the lumen during
insertion as well as thereafter means that unless the decision is
made to dispense with angioplasty and only stent, an antecedent
angioplasty will be necessary. By contrast, while accomplished
transluminally, miniballs are implanted with the same device that
is able to perform an angioplasty. When usable, the maximum
diameter of the muzzle-head that can be used is still likely to
prove preclusive of the level of barrel-assembly capability
desired. However, when a barrel-assembly can be used, the need for
an antecedent balloon angioplasty will have been averted, and the
advantages of higher implant insertion rate and precision in close
placement of the implants will have been gained. With less central
vessels that can be mantled about or largely so, reduced procedural
time and accomplishing a uniform distribution of implants quickly
will usually favor the use of a barrel-assembly.
[4501] XV6. Stays Coated with a Heat-Activated (-Melted,
-Denatured) Tissue Adhesive-Hardener, or Binder-Fixative
[4502] Miniballs coated with a heat-activated (-melted, -denatured)
tissue adhesive-hardener or binder and fixative such as a solid
protein solder are described below under the section entitled
Miniballs Coated with a Heat-activated (-melted, -denatured) Tissue
Adhesive-Hardener. Whereas the solders used to invest miniballs
should flow at lower temperatures for heating with the coils in the
muzzle-head of the angioplasty-capable barrel-assembly, a laser for
flowing stay solder can be attached alongside the stay insertion
tool. One advantage in the use of stays is that access to the
ductus for preliminary testing, for inserting the stays, for
applying heat to flow and set a tissue adhesive-hardener if
applicable, and for placing the stent-jacket are all done through
an incision through the adventitia and thus outside the lumen.
[4503] Where the greater speed of ballistic implantation with
miniballs had been opted for, results of the preliminary test
described below in the section entitled In Situ Test upon
Endoluminal Approach for Intra- or Inter-laminar Separation
(Delamination) will sometimes have indicated that to avoid the risk
of continued travel of a miniball between layers within the wall,
either the stent-jacket or double-wedge type stent-jacket as
described in the section above entitled Double-wedge Stent- and
Shield-jacket Rebound-directing Linings must be placed prior to
initiating discharge, or stays must be used instead, the choice
made based upon the specifics of the medical condition as
susceptible of less immediate trauma and freedom from sequelae by
the one method or the other, the detailed implications of which are
many.
[4504] More often it will be the lumen that would best be avoided,
so that the choice of stays over ballistic implantation is more
likely. If following curing, the tissue adhesive-hardener does not
allow gradual infiltration at its boundary to a depth within it
that sustains bonding relation to the replacement tissue, then
whether a stay or a miniball, adhesion to the implant will be
limited to the turnover rate of the fibers to which the adhesive
coating the implant initially bonded. This factor is of central
importance when intralaminar and interlaminar bonding that includes
the radially outward and inward surfaces of the implants is
essential to sustain the intraparietal integrity essential for the
implants to maintain the lumen patent.
[4505] Ideally, the tissue adhesive hardener behaves similarly to
scaffolding materials used in tissue engineering. It should be 1.
Tissue-infiltratable, 2. Susceptible to enzyme degradation as
necessary, and 3. Maintain adhesion as the tissue that was
originally bonded chemically is replaced, making necessary
mechanical bonding or the formation of new chemical bonds. Implants
to remain over many years should have nondegradably textured
surfaces that will allow mechanical bonding to the surrounding
tissue by infiltration once so much if not all of the tissue
adhesive-hardening agent subject to disintegration has
disappeared.
[4506] For the period preceding the complete deterioration of the
agent, the separation between adjacent miniballs or stays must be
adequate to distribute the bonding agent extensively enough to
preserve bonding during tissue renewal. The tissue once knit
together around and to the surface of the implant must possess the
required strength to withstand the tractive force. Stays provide
much greater bonding surface for knitting intraparietal separations
but do not allow a snugly fitting stent-jacket to be placed about
the ductus prior to implantation. With miniballs, this measure can
sufficiently reduce a separation as to allow dispensing with
additional measures.
[4507] Provided tissue replacement of the adhesive-hardener is
predictable, some slight inter- or intrapariental separation as is
filled with the adhesive-hardener is acceptable. Any tissue
hardener as might be injected into the weakened wall through the
local incision to prepare it for implantation would have to meet
the foregoing requirements and not prove excessively resistive to
the insertion of stays, although if not too hard, ballistic
implantation can achieve a suddenness and force of impact that
along with the small diameter, typically 0.4 millimeters, will
achieve penetration. The application to stays of a delayed tack
glue or tissue bonding agent is accomplished by adaptation of the
insertion hand tool, and is therefore described under the section
entitled
[4508] The ability to completely avoid the lumen an advantage of
stays, a die injection test that avoids luminal entry, described
below in the section entitled In Situ Test upon Extraluminal
Approach for Intra- or Inter-laminar Separation (Delamination), is
provided to detect a propensity for intraparietal separation. The
test is intended to indicate the magnetic traction the material of
the ductus wall can withstand before and after impregnation with an
adhesive-hardener and if needed, whether the same must be allowed
to fully cure before the stent-jacket is placed and the implants
brought under the magnetic traction of the stent-jacket. If so,
then stays should not be used.
[4509] With stays, the entire procedure, to include pre-testing,
placement of the implants, heating to melt a solder coating or
cooling by means of a `cooling` catheter on the insertion tool when
applicable, and placement of the stent-jacket are all through the
same incision, and thus most advantageous when accomplished during
a single procedure. For this reason, the ability to eliminate any
cause for deferring placement of the stent-jacket is advantageous.
When the ductus shows a propensity for intraparietal separation,
placement of the stent-jacket may have to be deferred until the
tissue adhesive-hardener has fully cured. This interval should not
exceed 24 hours, which while more than the time for one procedure,
is not excessive for preserving the ductus access incision and thus
allowing the use of stays.
[4510] The need for reincision at the same or usually a nearby
location is to be avoided. Longer curing times assume that the need
to restore patency is not urgent, which usually is not the case.
When urgent, to restore patency immediately, an anti-inflammatory
such as steroidal drug-eluting absorbable endoluminal stent is
inserted after placing miniballs. This allows deferring placement
of the stent-jacket for the period over which the absorbable stent
can be depended upon. Unless presenting some distinct advantage on
medical grounds, a tissue adhesive-hardener requiring longer than
24 hours to fully cure should be discounted. Instead, the
prepositioning of the stent-jacket for use with miniballs is
considered.
[4511] If the choice is for stays, then the test already performed
should supply conversion data as eliminates the need for a second
preliminary test described below under the section entitled In Situ
Test upon Extraluminal Approach for Intra- or Inter-laminar
Separation (Delamination), which is used when stays are opted for
ab initio to assess 1. The least outward radial tractive force or
magnetic field strength, hence, the least expensive, smallest, and
least obtrusive bar magnets and magnetic stent-jacket that would
serve to maintain luminal patency as least to encroach upon or
abrade against adjacent tissue, and 2. Whether the tunics or layers
within the ductus wall would a. Withstand a tractive force exerted
upon the implanted stays or miniballs by the bar magnets about the
outer surface of the stent-jacket base-tube that is sufficient to
maintain the lumen patent without separating within or between
(delaminating) the layers or tunics, or b. Whether to prevent the
wall from separating internally, the force required will
necessitate the use of stays or miniballs having an outer coating
of a tissue adhesive-hardener, such as a solid protein solder.
[4512] The thickness of the solder coating must not exceed the
distance the stay can be allowed to be pulled radially outward
within the wall of the ductus placing it closer to the
stent-jacket. Neither can the coating be so thick that during the
melting of the solder the stay is able to move significantly away
from a substantially concentric orientation. In contrast to the use
of stays having a coating of solid protein solder, the application
of a cyanoacrylate cement to the trailing end of each stay to seal
the incision made through the adventitia by the stay upon
insertion, or the stay insertion incision, is built into the stay
insertion tool to proceed automatically so long as an adhesive vial
or cartridge is installed in the tool, regardless of whether the
stays used are coated with a solid tissue adhesive-hardener.
[4513] Predenaturation having been determined to `significantly
reduce the solubility and consequently improve the handling
characteristics of protein solder` (McNally, K. M., Sorg, B. S.,
and Welch, A. J. 2000. "Novel Solid Protein Solder Designs for
Laser-assisted Tissue Repair," Lasers in Surgery and Medicine
27(2):147-157), application by air-suspension, pan tumble coating,
spray-drying, vibrational nozzle, plasma vapor, sputter-coating, or
any other process used in the pharmaceutical industry to apply a
coating of a material while fluid to a troche (pill, tablet) can be
used to apply the solder coat.
[4514] While denaturation of the solder so that it will flow into,
bond with, and infiltrate into the interstices of the tissue
surrounding the stay (or miniball) is not by heating through the
absorption of the energy cast by a laser beam by chromophores
dispersed through the solder or an absorbable polymer substrate
membrane, to preserve the know-how acquired, a porous layer of an
absorbable polymer can be applied to the implant as a substrate. To
be as reliable as the inherent variability through time of the
disease under treatment will allow, the test must be applied to the
actual tissue to be implanted. If any preliminary treatment of the
target tissue will alter its mechanical properties, the tissue must
be tested in the condition at implantation for the results of the
test to have any predictive value.
[4515] For example, when the ductus is affected over so short a
segment that stays to either side of the weakened tissue would
maintain its patency, to avoid aggravating and further weakening
the affected tissue with both the test and the implantation, the
test is performed on the stronger tissue to either side, which is
the tissue to be implanted. If the operator believes that the
injury to and weakening of the stronger tissue will leave that
tissue incapable of withstanding the tractive force of a magnetic
stent-jacket of the tractive force required without reinforcement,
or the ductus is uniformly weakened over a segment that is too
large to straddle and support the weakened portion at its sides,
then stays encapsulated with solid protein solder must be used and
warmed following insertion.
[4516] Because the stent-jacket is inserted through the same
incision as the stays, the treatment must leave the ductus with
sufficient strength to withstand the minimum tractive force
sufficient to maintain the lumen patent within the time of a single
procedure. The intraparietal use of a tissue adhesive-hardener
assumes that the prognosis is for stability if not improvement in
the strength of the ductus wall. For ductus that unlike arteries,
for example (see, for example, Dirsch, O., Dahmen, et al. 2004,
cited above in the section entitled Description of the Prior Art
and Conventional Practice in Vascular, Tracheobronchial, and
Urological Interventions), are poor in adapting to motile
restraint, the use of a stent-jacket lined with a cyanoacrylate or
solder adhesive is discouraged.
[4517] This is because unlike the use of a magnetic stent-jacket
with minimal tractive force, except for the ductus wall under the
stent-jacket side-slit or side-slot and therefore not bonded, the
use of an adhesive restrains the ductus in circumferential
expansion, and because any adhesive will become ineffective
according to the turnover rate of the substrate adventitial tissue,
the use of an adhesive in this way is limited to more short-term
diseases when the lumen is expected to recover patency once
healed.
[4518] XV7. Stays coated with a solid protein solder coating and
cyanoacrylate cement
[4519] Collagen and albumin based solders that will act in
combination with cyanoacrylate cement to flow and penetrate into
the interstices of the surrounding tissue at 55 degrees centigrade
(131 degrees Fahrenheit), then cool to act as a tissue hardener
with strong bonding to the surrounding tissue have already been
developed. To protect the surrounding tissue, these are recommended
for pinpoint heating by means of a laser (see, for example, Soltz,
B. A., Devore, D. P., Devore, B. P., Soltz, R. and Soltz, M. A.
2005. "Composite Tissue Adhesive," U.S. Pat. No. 6,939,364). While
heating solder-coated implants following insertion may be an
option, to do so exposes the tissue to heat over a longer
period.
[4520] For this reason, it is preferred to use electrically or
fluidically controlled solder injection-syringe tool-inserts such
as shown in FIGS. 54 and 59 respectively, which can heat and
maintain the syringe contents at a constant temperature.
Injection-syringe tool-inserts are addressed below in the section
entitled Radial Projection Units. To coat stays as each ejects from
a stay insertion tool having a heated chamber is rejected as little
of the solder would pass through with the stay. To reduce the
removal of adhesive or medication, the surface of the stay is
textured and grooved or ribbed.
[4521] Newer tissue cements developed for corneal application
include Dextran Aldehyde-PEG Amine (see, for example, Chenault, H.
K., Bhatia, S. K., Dimaio, W. G., Vincent, G. L., Camacho, W., and
Behrens, A. 2011. "Sealing and Healing of Clear Corneal Incisions
with an Improved Dextran Aldehyde-PEG Amine Tissue Adhesive,"
Current Eye Research 36(11):997-1004) and chondroitin
sulfate-polyethylene glycol (Strehin, I., Ambrose, W. M., Schein,
O., Salahuddin, A., and Elisseeff, J. 2009. "Synthesis and
Characterization of a Chondroitin Sulfate-polyethylene Glycol
Corneal Adhesive," Journal of Cataract and Refractive Surgery
35(3):567-576). As described below in the section entitled
Mechanism for Adjustment in Stay Insertion Tool Ejection Cycle
Inmate Cement Delivery Interval, when the cyanoacrylate is ejected
just prior to insertion of the stay, the stay passes through the
adhesive and into the wall of the ductus.
[4522] Such a surface treatment thus allows an increase in the
amount of adhesive that is carried forward into the wall. As
addressed below in this section, the addition of a retardant such
as glacial acetic acid will extend the open time of a cyanoacrylate
cement, and the addition of radiographic contrast will extend the
open time even more. However, in the present application, where the
solder coats the stay and becomes enclosed past the stay insertion
incision so that pinpoint heating with a laser is not possible, the
temperature should not exceed 49 degrees Celsius (120 degrees
Fahrenheit) when the solder must continue to be heated for a period
of minutes, or about 54.4 degrees centigrade (130 degrees
Fahrenheit) when sufficient infiltration of the melted solder into
the surrounding tissue takes less than half a minute.
[4523] Due to the minuteness in absolute amount, small ratio of
volume to surface area, and proximity to the source of heat of the
solder, flow and penetration can be achieved within this interval.
Admixture with a solid albumin solder can be used to increase bond
strength (see, for example, McNally, Sorg, and Welch 2000, Op
cit.). The advent of solid rather than merely viscous or thick
syrupy protein solders eliminates the need for a porous polymer
membrane scaffold as would raise the melting point (see Maitz, P.
K. M., Trickett, R. I., Tos, P., Lanzetta, M., Owen, E. R., Dekker,
P., Dawes, J. M., and Pipet, J. A. 2000. "Tissue Repairs Using a
Biodegradeable Laser-activated Solid Protein Solder," Conference on
Lasers and Electro-Optics, page(s):446-447; McNally, K. M., Dawes,
J. M., Parker A. E., Lauto, A., Piper, J. A., and Owen, E. R. 1999.
"Laser-activated Solid Protein Solder for Nerve Repair: In Vitro
Studies of Tensile Strength and Solder/Tissue Temperature," Lasers
in Medical Science 14(3):228-237).
[4524] The contradictory representations made concerning
cyanoacrylate cements and the controversy concerning butyl
cyanoacrylate cement in particular are addressed in the section
above entitled Specification of Cyanoacrylate Tissue Sealants and
Bonding Agents.
[4525] Almost all surgical adhesives currently available, to
include short carbon chain cyanoacrylates,
albumin-glutaraldehyde-based glue (Azadani, A. N., Matthews, P. B.,
Ge, L., Shen, Y., Jhun, C. S., Guy, T. S., and Tseng, E. E. 2009.
"Mechanical Properties of Surgical Glues Used in Aortic Root
Replacement," Annals of Thoracic Surgery 87(4):1154-1160;
Wippermann et al. cited above; Schiller, W., Rudorf, H., Welzel, C.
B., Kiderlen, M. J., Probst, C., Dewald, O., and Welz, A. 2007.
"Sutureless Anastomoses of Rabbit Carotid Arteries with BioGlue,"
Journal of Thoracic and Cardiovascular Surgery 134(6):1513-1518;
Schiller, W., Rudorf, H., Kiderlen, M. J., Welzel, C. B., Schmitz,
C., Probst, C., and Welz, A. 2007. "Short-term Tissue Response of
Lapine Carotid Artery Microanastomoses to BioGlue," Thoracic and
Cardiovascular Surgery 55(5):298-303) and
gelatin-resorcinol-formaldehyde-based glue (Izutani, H., Shibukawa,
T., Kawamoto, J., Ishibashi, K., and Nishikawa, D. 2007.
"Devastating Late Complication for Repair of Type A Acute Aortic
Dissection with Usage of Gelatin-Resorcinol-Formalin Glue,"
Interactive Cardiovascular and Thoracic Surgery 6(2):240-242; Hata,
H., Takano, H., Matsumiya, G., Fukushima, N., Kawaguchi, N., and
Sawa, Y. 2007. "Late Complications of Gelatin-Resorcin-Formalin
Glue in the Repair of Acute Type A Aortic Dissection," Annals of
Thoracic Surgery 83(5):1621-1627; Kamada, T., Nakajima, T.,
Izumoto, H., Sugai, T., Yoshioka, K., and Kawazoe, K. 2005. "Late
Complications Following Surgery for Type A Acute Aortic Dissection
Using Gelatin-Resorcin-Formaldehyde Glue: Report of Two Cases,"
Surgery Today 35(11):996-999) have been impugned (see, for example,
Bernabeu, E., Castella, M., Barriuso, C., and Mulet, J. 2005.
"Acute Limb Ischemia Due to Embolization of Biological Glue after
Repair of Type A Aortic Dissection," Interactive Cardiovascular and
Thoracic Surgery 4(4):329-331).
[4526] However, some workers may not have adequately distinguished
between superficial inflammation at the application site and
interference with healing (see, for example, Buijsrogge, M. P.,
Verlaan, C. W., van Rijen, M. H., Grundeman, P. F., and Borst, C.
2002. "Coronary End-to-side Sleeve Anastomosis Using Adhesive in
Off-pump Bypass Grafting in the Pig," Annals of Thoracic Surgery
73(5):1451-1456), and some may not have employed proper application
techniques (Fehrenbacher, J. W. and Siderys, H. 2006. "Use of
BioGlue in Aortic Surgery: Proper Application Techniques and
Results in 92 Patients," Heart Surgery Forum 9(5):E794-E799;
Nishimori, H., Hata, A., and Sasaguri, S. 2000. "Optimal
Application of Gelatin-resorcin-formaldehyde Glue with Special
Reference to the Quality of Mixing," Annals of Thoracic Surgery
69(4):1299).
[4527] The use of a relatively low viscosity tissue cement (tissue
sealant, surgical cement) or medicament allows the complexity,
precision, power, and expense of advancement mechanisms used to
drive high viscosity materials such as caulk and grease guns to be
avoided and the distal portions of the tool for insertion into the
body kept narrow to allow minimal entry incisions. Air pump
piston-plunger 233 is seen most clearly in FIGS. 87 and 102, with
addtional views appearing in FIGS. 89, 95, 97, 98, 99. The use of
low viscosity tissue cement requires the prevention of backup
seepage about the edges of cement or medication refill cartridge
plunger-plug 234 at the top of cement refill cartridge 235 (not to
be confused with air pump piston-plunger 233 used to eject adhesive
236), which would disable air pump piston-plunger 233.
[4528] The adhesive delivery line that is built into the stay
insertion tool thus consists of a single channel for the delivery
of a one-part (single-component) only cement, such as Ethicon
Omnex.TM. cyanoacrylate surgical sealant. Cyanoacrylate cements,
with or without a retardant and radiographic contrast added, tend
toward thinness in consistency and are more readily delivered
through tubing of capillary diameter than are numerous alternative
adhesives, to include some tissue sealants that consist of more
than one component. Nevertheless, the immediate availability of a
thicker tissue sealant for use as a hemostatic is desirable.
[4529] An auxiliary adhesive delivery line attached alongside the
tool by means of a holder described below in the section entitled
Powered Stay Insertion Tool Holder for the Atttachment of
Medication or Tissue Sealant Syringes Whether Single, Dual, or
Multi-chambered as Supplied for Tool Slave-follower or Independent
Use can be larger in diameter and thus conduct adhesives or any
syringe-deliverable (fluid) adhesive or medication that is thicker
in consistency. The holder can be used to control the delivery of
this substance either independently of or as operationally linked
or timing locked to stay insertion. These may consist of two or
more components which must be kept separate until polymerization
(setting) is to be initiated.
[4530] Such adhesive-sealants are typically sold in dual-chambered
syringe dispensers which are best integrated into the operation of
the tool without modification or only such modification as is
essential. The use of an attached syringe to supply a hemostat to
the treatment site requires function independent of the stay
insertion function, as will be described below in the section
entitled Use of Attached Adhesive Syringes Independently of Stay
Insertion. At the same time, a single component adhesive eliminates
component combination time as a variable affecting the interval
prior to reaching initial set, and such an adhesive is delivered by
means of the line contained within the insertion tool.
[4531] Once the components have been combined, an interruption in
the procedure, depending upon its duration, may make it neceesary
to replace the syringe and line. The cyanoacrylate cement will
solidify at the end of the delivery tube; however, a needle and an
acetone-soaked piece of gauze, not the need to replace the
applicator, allow continuation. Moreover, by the time of filing, no
two- or more-part (multiple-component, multi-component, multi-part)
adhesive had approached several commercially available
cyanoacrylate cements in such key factors as strength of bond,
quickness of setting time without a retardant (as discussed above
in the section entitled Specification of Cyanoacrylate Tissue
Sealants and Bonding Agents), and low viscosity that with the
addition of a retardant allows good penetration of tissue
interstices.
[4532] Since new developments could change that, and the internal
mechanism of the insertion tool is meant to support only the use of
single component adhesives, provision is made for the attachment of
commercial multi-component tissue adhesive-hardener dispensers or
applicators, as described below in the section entitled Powered
Stay Insertion Tool Holder for the Atttachment ofMedication or
Tissue Sealant Syringes Whether Single, Dual, or Multi-chambered as
Supplied for Tool Slave-follower or Independent Use. A `cooling`
catheter with side-holes and/or a small end-hole can also be
attached to a dual syringe, for example, to extend the adhesive
open time when blown with cold air, CO.sub.2, or N.sub.2O, or
reducing the open time when blown with heated air.
[4533] In practice, the preliminary test referred to above, which
is described below in the section entitled In Situ Test upon
Extraluminal Approach for Intra- or Inter-laminar Separation
(Delamination), is required only when the medical condition of the
ductus makes the use of an adhesive-hardener that must be heated to
melt objectionable. Then, either a. The intrinsic strength of the
wall must have been confirmed to be adequate in strength to sustain
the tractive force of the magnetic stent-jacket without
reinforcement by an adhesive-hardener, or b. The amount of
cyanoacrylate cement applied to the stays must be increased to not
only seal the stay insertion incision but compensate for the lack
of a solid protein solder as a binding and hardening agent or
fixative that requires the application of a higher temperature to
use.
[4534] Because ballistic implantation precludes the initial and
quick use of any fluid cement, recourse to an alternative tissue
bonding and hardening agent such as a cyanoacrylate cement that
need not be denatured (heated until melted) is an advantage in the
use of stays, which can be applied to the treatment of a larger
diversity of lesion types to include those which should not be
heated. The use of cyanoacrylate cement to bind miniballs to and
harden the tissue surrounding them, as discussed below in the
section entitled Cyanoacrylate Injection Catheter, is secondary,
and if the treatment site is extensive or multiple, may become
time-consuming and tedious.
[4535] The mechanism for adjusting the adhesive emission interval,
thus allowing adjustment in the amount of adhesive applied to each
stay is described below in the section entitled Mechanism for
Adjustment in Stay Insertion Tool Ejection Cycle Cement Delivery
Interval. When either a. The condition will allow the use of stays
having an outer layer of albumin-collagen solder that must be
heated or b. The use of additional cyanoacrylate in lieu of solder
is unobjectionable, then procedural time can be reduced by assuming
from the outset that the layers within the wall of the ductus will
separate, proceed to use adhesive as a perfunctory step barring
special circumstances, and dispense with preliminary testing.
[4536] To flow into the interstices or intraparietal intra- or
interlaminar separations in the tissue surrounding the stays, the
ideal cyanoacrylate cement would be both thin (low in viscosity)
and remain fluid (open) long enough to saturate these. More
specifically, in unexceptional circumstances, any adhesive used to
seal the stay insertion incision and, if necessary, serve as a
tissue bonding and hardening agent is preferably:
[4537] 1. Single-component.
[4538] 2. Not soluble in body fluids.
[4539] 3. In the absence of moisture, remains fluid (thin, light)
at room temperature or while chilled to extend the open time so
that even when the tool must be long to reach a more considerable
working depth, the adhesive when mixed with the radiographic agent
Lipiodol.TM. and tungsten powder (Suh, D. C., Shi, H. B., Park, S.
S., Lee, M. S., and Choi, H. Y. 2000. "Change of Spontaneous
Reaction of Glue and Lipiodol Mixture During Embolization after the
Addition of Tungsten Powder: In Vitro Study," American Journal of
Neuroradiology 21(7):1277-1279) will pass entirely through without
clogging the insertion tool delivery line.
[4540] 4. Fluid, if necessary, with the aid of chilling once
intraparietal as essential for infiltrating and wetting the
surrounding tissue, but which
[4541] 5. Sets quickly when heated, and
[4542] 6. Is not susceptible to enzyme degradation when such occurs
too rapidly for the connective tissue to displace the adhesive,
allowing the stay insertion incision and the tissue subjacent to it
to mend.
[4543] However, the thinner a cyanoacrylate cement is, the shorter
is its open time, and while chilling a cyanoacrylate cement will
retard its initial setting time, to do so also increases its
thickness (viscosity), likewise reducing if not negating its
ability to continue to flow until it has fully penetrated the
tissue. These factors make the use of cyanoacrylate cement to coat
miniballs, and therewith the ability to avoid heating the tissue
treated as required by a solid solder coating, impracticable,
reducing the number of lesion types treatable with miniballs
compared to stays. Moreover, since cyanoacrylate cement is not
solvent based, its fluidity and open time are substantially
unaffected by adding solvents such as acetone and super glue
removers or surface active agents (wetting agents, surfactants,
tensides), which are nontoxic, especially in the minute amounts
that pertain, but in relation to which cyanoacrylate cement lose
bond strength and are immiscible.
[4544] The established ways to extend the open time of a
cyanoacrylate cement are to or mix the cement with radiographic
contrast or acetic acid or to pre-coat the surface to be bonded
with acetic acid; the latter not practicable for applications
described herein. Accordingly, the use of an approved surgical
cyanoacrylate, currently Ethicon Omnex.TM. cyanoacrylate surgical
sealant in the U.S., is preferred without modification that is not
clearly essential. The cement is packaged in stay insertion tool
cartridges with fluidity and curing characteristics at various
temperatures specified. Consisting of a single component,
cyanoacrylate cement also allows simplification in requiring no
more than one line (tube, lumen, channel) for delivery to the upper
surface of each stay as it emerges from the ejection slot of the
stay insertion tool.
[4545] For reasons of reaching initial set quickly and end bond
strength, cyanoacrylate cement will be preferable to dual component
adhesives under most circumstances. Future two-component tissue
sealants may have faster curing times once the components are
combined to initiate setting through polymerization. This would be
readily accommodated by segregating the components in separate
lines would detain blending until the components were within close
reach of the end opening above the stay ejection slot. A miniature
version of the type mixing nozzle used to mix epoxy cements is used
to thoroughly blend the components. Such a nozzle is seen in the
BioGlue.RTM. (CryoLife) dual syringe.
[4546] The mechanism for adjusting the cyanoacrylate emission
interval, thus allowing adjustment in the moment of initiation and
the amount of adhesive applied to each stay is described below in
the section entitled Mechanism for Adjustment in Stay Insertion
Tool Ejection Cycle Cement Delivery Interval. An alternative form
of control for two-component adhesives is described below in the
section entitled Powered Stay Insertion Tool Holder for the
Atttachment of Medication or Tissue Sealant Syringes Whether
Single, Dual, or Multi-chambered as Supplied for Tool
Slave-follower or Independent Use. Both the built in
single-component and attached two-component adhesive delivery
devices can have a `cooling` (temperature changing) catheter with
side and/or end hole for cooling or heating the tissue under
treatment attached alongside.
[4547] While a cooling catheter must have side perforations if not
an end perforation, a line for the delivery of hot or cold air,
cold gas, or suction to the target tissue, unless needed at the
same time, can all be through the same line or tube attached to the
insertion tool by means of clips. Otherwise, one line is attached
for suction, another for heating, and so on. Cyanoacrylate cements
achieve initial set more quickly the more thin in consistency, or
less viscous. Premature setting as would clog an adhesive delivery
line whether inmate or attached to an insertion tool and thus
interfere with implantation can, however, be averted.
[4548] Mixing the cyanoacrylate with Lipiodol.TM., tungsten powder
(Suh, Shi, Park, Lee, and Choi 2000. as cited above) and/or acetic
acid and/or with the aid of a cooling catheter having side-holes
installed in the insertion tool side clips as described below under
the section entitled Stay Insertion Tool Mounting Spring Clips; the
use of cooling will retard setting but increase the viscosity or
thickness of the cyanoacrylate cement. Any accumulation must be
periodically purged or flushed, which can be through an aspeiration
line independent of the tool, a syringe with catheter connected
directly to refill cartridge puncture pin seen as 237 in FIGS. 87
and 102, a refill cartridge containing a cleaning agent such as
acetone or a commercial cyanoacrylate cleaning solution as
specified in the below section entitled Use of Stay Insertion Tool,
or if not needed at the same time, the same line used as a suction
line or end-delivery cooling catheter, meaning a tube having only a
hole or holes at its distal end for blowing chilled air or gas, or
heated air at the treatment site.
[4549] To do this, the refill cartridge chamber side-entry
snap-cover as described below in the section entitled Sealant
Cartridges and Sealants (Adhesives) is removed, the attached line
pulled out of the spring clips, its distal end placed over the
adhesive cartridge puncture pin at the top of the adhesive line
237, and the cleaning solution injected at the proximal end of the
line by means of a syringe. Once reattached, the line can be used
to accelerate setting or curing, heated air can be delivered to the
working spot on the outside of the ductus by a tube or hose
connected to the hot outlet of a cold air gun with its own
temperature control. The line can also be periodically flushed with
a cartridge that contains cleaning fluid, a small hose, or a
hypodermic needle used to inject acetone into adhesive cartridge
puncture pin 237, as described below in the section entitled Use of
Stay Insertion Tool (Stay Inserter) with the aid of cartridges
filled with a solvent such as acetone to prevent or remedy any
buildup of adhesive.
[4550] While most surgical adhesives initially set in about 24
seconds, the quickest to cure, cyanoacrylate cements, require at
least two hours to reach full bonding strength, and non-acrylate
based adhesives, because these initially set to form a weaker bond
(Garcia Paez, J. M., Jorge Herrero, E., Rocha, A., Maestro, M.,
Castillo-Olivares, J. L., Millan, I., Carrera Sanmartin, A., and
Cordon, A. 2004. "Comparative Study of the Mechanical Behaviour of
a Cyanoacrylate and a Bioadhesive," Journal of Materials Science.
Materials in Medicine 15(2):109-115; Garcia Paez, J. M., Jorge
Herrero, E., Millan, I., Rocha, A., Maestro, M., Castillo-Olivares,
J. L., Carrera Sanmartin, A., and Cordon, A. 2004. "Resistance to
Tensile Stress of a Bioadhesive Utilized for Medical Purposes:
Loctite 4011," Journal of Biomaterials Applications 18(3):179-192),
make necessary means alongside the insertion tool for applying heat
to accelerate curing.
[4551] XV8. Use of Cement and Solder Coated Stays
[4552] The use of cement and of solder-coated stays is primarily
intended for use when preliminary testing as described below in the
section entitled In Situ Test upon Extraluminal Approach for Intra-
or Inter-laminar Separation (Delamination) reveals that the wall is
predisposed toward intra or interlaminal separation. The adhesive
will fail during a period shorter than the turnover rate of the
majority of the cells at the bond interface; however, depending
upon the condition, the replacement cells will usually supplant
cement and/or solder as continuous tissue before the latter is
dissipated.
[4553] A stay inserter can be used to implant any kind of stays,
whether stent-stays containing ferrous metal for use with a
stent-jacket or magnet-wrap, or stays that consist purely of
medication, of time-released layers of medication, stays that
include an irradiating seed, or serve as an absorbable temporary or
a nonabsorbable permanent structural support to avert the collapse
of a ductus. Stays can be prepared that combine these features, and
stay refill-strip can be prepared to queue different type stays in
any sequence, thus allowing the operator to alternate the type
stays implanted along the ductus. Since stent-jackets are not
recommended for ductus invested in tissue such as skeletal muscle,
stent-stays are not used for such structures; however, stays can be
used to implant medication or a source of radiation ductus
intramurrally.
[4554] In this circumstance, when the segment of the ductus to be
implanted would necessitate multiple entry wounds to access the
ductus at the substantially right angle required by an ordinary
inserter, the number of entry wounds is reduced by using an
inserter with a flexible joint as described below in the section
entitled Insertion Tool with Flexible Joint. When the decision to
introduce implants must pend a close visual examination of the
proposed treatment site, a stay inserter can be used as a delivery
platform for the endoscope and aspirator which because it can also
mount alongside a laser, affords the immediate options for
treatment by laser and/or the insertion of stays.
[4555] The cyanoacrylate cement is usually mixed with contrast
agent and acetic acid, which detain initial setting to allow a
solid protein solder coating on the stay to be melted by means of a
temperature-changing or `cooling` catheter attached to the tool.
The use of a curing accelerator or primer is unaccommodated as an
impediment. The attachment of ancillary lines to a stay insertion
tool is addressed below in the section entitled Binding of Lines
and Cables Alongside the Stay Insertion Tool. Ductus-intramural
separation testing in preparation to implant stays is addressed
below in the section entitled In Situ Test upon Extraluminal
Approach for Intra- or Inter-laminar Separation (Delamination).
[4556] The stay insertion tool to be described in the following
section allows switching from cement-ahead to cement-follow
operation at any moment during a procedure and allows the amount of
cement applied in either mode to to be varied. In cement-follow
operation, cement can be applied to only the trailing end of the
upper surface of each stay and thus only for the purpose of bonding
the stay insertion incision closed. This allows cement to be
limited to only the trailing tip of each stay for the purpose of
sealing its insertion incision into the wall of the ductus.
[4557] Coating the entire surface of a stay will generally allow
the cement to spread at its periphery contributing to the temporary
resistance to separation. The tool shown in FIG. 89 is of pistol
configuration that ejects cement over a variable length of the
upper surface of the stay and injects the stay when the `trigger`
is pulled back. Using a pistol configured stay insertion tool, the
movement of the operator is the reverse of that with the
syiringe-configured tool even though the ejection mechanism as such
is the same.
[4558] XV9. Specification of Cyanoacrylate Tissue Sealants and
Bonding Agents
[4559] The citation of short or long-chain cyanoacrylate cement
herein is subject to continued research with regard to
histotoxicity and carcinogenicity. In direct contact with tissue
rather than used in fabricating the implant, such as to fasten the
bar magnets about the outer surface of the base-tube, some have
described long-chain plastic glues such as butyl 2-cyanoacrylate
and octyl-cyanoacrylate as more slowly degraded with some incision
line encrustation or microcrystallization residue remaining but
less histotoxic than short-chain glues such as methyl- and
ethyl-cyanoacrylate (Toriumi, D. M., Raslan, W. F., Friedman, M.
and Tardy, M. E. 1990. "Histotoxicity of Cyanoacrylate Tissue
Adhesives. A Comparative Study," Archives of Otolaryngology--Head
and Neck Surgery 116(5):546-550; Levrier, O., Mekkaoui, C.,
Rolland, P. H., Murphy, K., Cabrol, P., Moulin, G., Bartoli, J. M.,
and Raybaud, C.2003. "Efficacy and Low Vascular Toxicity of
Embolization with Radical Versus Anionic Polymerization of
n-butyl-2-cyanoacrylate (NBCA). An Experimental Study in the
Swine," Journal of Neuroradiology 30(2):95-102; comment by Haber,
G. B. 2004. "Tissue Glue for Pancreatic Fistula," Gastrointestinal
Endoscopy 59(4):535-537 concerning Seewald et al. cited in
following paragraph; Pachulski, R., Sabbour, H., Gupta, R., Adkins,
D., Mirza, H., and Cone, J. 2005. "Cardiac Device Implant Wound
Closure with 2-octyl Cyanoacrylate," Journal of Interventional
Cardiology 18(3):185-187.). Long-chain advocates do, however,
reject isobutyl-2-cyanoacrylate (bucrylate) as a potential
carcinogen (Vinters, H. V. Balil, K. A., Lundie, M. J. and
Kaufmann, J. C. 1985. "The Histotoxicity of Cyanoacrylates,"
Neuroradiology 27(4):279-291; Vinters, H. V., Debrun, G., Kaufmann,
J C , and Drake C. G. 1981. "Pathology of Arteriovenous
Malformations Embolized with Isobutyl-2-cyanoacrylate (Bucrylate).
Report of Two Cases," Journal of Neurosurgery 55(5):819-825).
Cyanoacrylate cement is also addressed in the section below
entitled Sealing of Stay Insertion Incisions.
[4560] While preferred as an alternative to ultrasonic welding for
fabricating some of the nonimplanted apparatus described herein,
butyl 2-cyanoacrylate (B2-CA) cement is not preferred for sealing a
stay insertion incision wound as non-bioabsorbable, in the gut, at
least, bioincompatible (see, for example, Nursal, T. Z., Anarat,
R., Bircan, S., Yildirim, S., Tarim, A., and Haberal, M. 2004. "The
Effect of Tissue Adhesive, Octyl-cyanoacrylate, on the Healing of
Experimental High-risk and Normal Colonic Anastomoses," American
Journal of Surgery 187(1):28-32), and believed by some, to be
potentially carcinogenic (comment by Haber, G. B. 2004 cited in
preceding paragraph; Vinters et al. 1985 cited cited in preceding
paragraph; Samson, D. and Marshall, D. 1986. "The Carcinogenic
Potential of Iso-butyl-2 Cyanoacrylate," (Letter) Journal of
Neurosurgery 65:571-572), which others do not report despite
lengthy followup to the same use (Seewald, S., Brand, B., Groth,
S., Omar, S., and eight other authors 2004. "Endoscopic Sealing of
Pancreatic Fistula by Using N-butyl-2-cyanoacrylate,"
Gastrointestinal Endoscopy 2004 59(4):463-470) or a different use
(Saba et al. cited above; Tebala, G. D., Ceriati, F., Ceriati, E.,
Vecchioli, A., and Nori, S. 1995. "The Use of Cyanoacrylate Tissue
Adhesive in High-risk Intestinal Anastomoses," Surgery Today
25(12):1069-1072; Brown, L. D.; Smith, C. D.; Lollini, L. O.; and
Korte, Don W., Jr 1988. "A Carcinogenicity Bioassay of Isobutyl
2-Cyanoacrylate (IBC) in Fischer-344 Rats--One-Year Interim
Sacrifice Report. Volume 2. Part 1," Defense Technical Information
Center Accession Number ADA201448 [available at
http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identif-
ier=ADA201448]).
[4561] The indictment of short-chain or absorbable cyanoacrylates
as tissue adhesives has also been contradicted by researchers who
report that ethyl 2-cyanoacrylate is excreted from the body intact,
with no mention of degradation or the liberation of formaldehyde as
does Haber cited in the preceding paragraph (see, for example,
Kaplan, M., Oral, B., Rollas, S., Kut, M. S., and Demirtas, M. M.
2004. "Absorption of Ethyl 2-cyanoacrylate Tissue Adhesive,"
European Journal of Drug Metabolism and Pharmacokinetics
29(2):77-81). Moreover, the same group has asserted that ethyl
2-cyanoacrylate can be used in vascular, myocardial and pulmonary
surgery without concern for toxicity (Kaplan, M., Bozkurt, S., Kut,
M. S., Kullu, S., and Demirtas, M. M. 2004. "Histopathological
Effects of Ethyl 2-cyanoacrylate Tissue Adhesive Following Surgical
Application: An Experimental Study," European Journal of
Cardio-thoracic Surgery 25(2): 167-172).
[4562] In small amounts used superficially, as when closing
following the placement of subcutaneous clasp magnets, butyl
2-cyanoacrylate would appear to be relatively risk free (see, for
example, Canonico, S., Campitiello, F., Santoriello, A., Canonico,
R., Ciarleglio, F. A., and Russo, G. 2001. "Sutureless Skin Closure
in Varicose Vein Surgery: Preliminary Results," Dermatologic
Surgery 27(3):306-308), while for closing stay insertion tool
adventitial or medial incisions, insistence upon a longer chain
adhesive such as octyl-cyanoacrylate appears warranted until such
time as a cyanoacrylate cement which is absorbable and
nonencrusting becomes available (Seifman, B. D., Rubin, M. A.,
Williams, A. L., and Wolf, J. S. 2002. "Use of Absorbable
Cyanoacrylate Glue to Repair an Open Cystotomy," Journal of Urology
167(4):1872-1875).
[4563] Given contradictory information, the adhesive used to bond
the lining to the internal surface of the base-tube, which is fully
cured during manufacture and as cured involves little tissue
contact, is based upon the materials of which the components to be
bonded are made. Since octyl-cyanoacrylate and
N-butyl-2-cyanoacrylate are generally agreed upon as posing the
least risk, these, along with tissue sealants of different
chemistry specified in the section below entitled Sealant
Cartridges and Sealants (Adhesives) are preferred for all
applications described herein that involve sealing tissue rather
than an extracorporeal assembly of components with cyanocrylate
cements not brought into extended or intimate contact with
tissue.
[4564] Provided heat is applied to accelerate curing, vascular
graft closure 2-octyl cyanoacrylate adhesives produced by the
Closure Medical division, Johnson & Johnson Ethicon (Ethicon
Omnex.TM. Surgical Sealant), approved in the U.S., which is
preferred or alternately Glubran 2 N-butyl-2-cyanoacrylate and
methacryloxysulfolane produced by Gem Viareggio, Lucca Italy,
approved in Europe, Neuracryl.TM. 2-hexyl cyanoacrylate (see, for
example, Krall, R. E, Kerber, C. W., and Knox, K. 2002.
"Compositions for Creating Embolic Agents and Uses Thereof," U.S.
Pat. No. 6,476,069), Histoacryl.TM. n-butyl 2 cyanoacrylate
produced by B. Braun Surgical GmBH (see Krall et al. just cited;
Rosin, D., Rosenthal, R. J., Kuriansky, J., Brasesco, O., Shabtai,
M., and Ayalon, A. 2001. Closure of Laparoscopic Trocar Site Wounds
with Cyanoacrylate Tissue Glue: A Simple Technical Solution,
Journal of Laparoendoscopic and Advanced Surgical Techniques 11(3):
157-159) for example, appear to meet if not exceed the requirements
for sealing stay insertion incision wounds (see, for example,
Brunkwall, J., Ruemenapf, G., Florek, H. J., Lang, W., and
Schmitz-Rixen, T. 2007. "A Single Arm, Prospective Study of an
Absorbable Cyanoacrylate Surgical Sealant for Use in Vascular
Reconstructions as an Adjunct to Conventional Techniques to Achieve
Haemostasis," Journal of Cardiovascular Surgery (Turin, Italy)
48(4):471-476; Lumsden, A. B. and Heyman, E. R. 2006 "Prospective
Randomized Study Evaluating an Absorbable Cyanoacrylate for Use in
Vascular Reconstructions," Journal of Vascular Surgery
44(5):1002-1009).
[4565] To enhance visibility and retard premature setting, surgical
cyanoacrylate adhesives are routinely mixed with a radiographic
contrast agent such as Lipiodol.TM., to which may be added tungsten
powder (Suh, D. C., Shi, H. B., Park, S. S., Lee, M. S., and Choi,
H. Y. 2000. "Change of Spontaneous Reaction of Glue and Lipiodol
Mixture During Embolization After the Addition of Tungsten Powder:
In Vitro Study," American Journal of Neuroradiology
21(7):1277-1279), or acetic acid. The acetic acid may additionally
induce the formation of an encapsulating layer of dense collagenous
(scar) tissue to increase the resistance of the implant to
pull-through under the magnetic force of the stent-jacket. However,
this potential benefit of scar tissue only gains strength over much
time.
[4566] The relative proportion of acetic acid used must consider
that scar tissue is initially formed by the infilling of the
injured tissue by a proteinaceous exudate that while it will
eventually assist in anchoring and isolating the implant, will for
a time weaken the interface surrounding the implant. Auxiliary
syringes attached to a stay insertion tool make it possible to
simultaneously or sequentially deliver agents for temporarily
increasing the thickness of the ductus wall (in an artery, the
intimal-medial thickness or IMT) and inducing the formation of scar
tissue.
[4567] The cements specified herein for implantation, to include
cyanoacrylate cement for intraparietal injection to bond minialls,
for example, and a solid protein solder as an outermost layer or
coating for miniballs, for example, can be provided in modified
formulations that will allow use to assemble absorbable implant
components. Placed in contact with tissue, these should not evoke
more than a tolerable adverse tissue reaction, which a release of
medication by the cement as it disintegrates can ameliorate.
Absorbable components are preferably bonded with absorbable cements
of like breakdown time; although a slight residue, even
nonabsorbable should pose little risk.
[4568] These cements also include both hydrogels but only when the
swelling that follows application that is largely responsible for
its hemostatic effect valued in alternative applications can be
accommodated by applying a proportionately smaller amount (see, for
example, Yin, L., Fei, L., Cui, F., Tang, C., and Yin, C. 2007.
"Superporous Hydrogels Containing Poly(acrylic
acid-co-acrylamide)/O-carboxymethyl Chitosan Interpenetrating
Polymer Networks," Biomaterials 28(6):1258-1266; Ishihara, M.,
Fujita, M., Obara, K., Hattori, H., Nakamura, S., Nambu, M.,
Kiyosawa, T., Kanatani, Y., Takase, B., Kikuchi, M., and Maehara,
T. 2006. "Controlled Releases of FGF-2 and Paclitaxel from Chitosan
Hydrogels and Their Subsequent Effects on Wound Repair,
Angiogenesis, and Tumor Growth," Current Drug Delivery
3(4):351-358; Ishihara, M., Obara, K., Nakamura, S., Fujita, M.,
Masuoka, K., Kanatani, Y., Takase, B., Hattori, H., Morimoto, Y.,
Ishihara, M., Maehara, T., and Kikuchi, M. 2006. "Chitosan Hydrogel
as a Drug Delivery Carrier to Control Angiogenesis," Journal of
Artificial Organs 9(1):8-16; Serra, L., Domenech, J, and Peppas, N.
A. 2006. "Design of Poly(ethylene Glycol)-tethered Copolymers as
Novel Mucoadhesive Drug Delivery Systems," European Journal of
Pharmaceutics and Biopharmaceutics 63(1):11-18; Hu, B. H. and
Messersmith, P. B. 2005. "Enzymatically Cross-linked Hydrogels and
Their Adhesive Strength to Biosurfaces," Orthodontics and
Craniofacial Research 8(3):145-149; Roorda, W. E., Bodde, H. E., de
Boer, A. G., Bouwstra, J. A., and Junginger, H. E. 1986. "Synthetic
Hydrogels as Drug Delivery Systems," Pharmacy World and Science
[Pharmaceutisch Weekblad. Scientific Edition] 8(3):165-189) and
cyanoacrylates, (see, for example, "Local Delivery of Vancomycin
for the Prophylaxis of Prosthetic Device-related Infections,";
Eskandari M M, Ozturk O G, Eskandari H G, Balli E, and Yilmaz C.
2006. "Cyanoacrylate Adhesive Provides Efficient Local Drug
Delivery," Clinical Orthopaedics and Related Research
451:242-250).
[4569] Cyanoacrylate cements referred to in this specification can,
as has long been practiced, be mixed with a radiographic contrast
agent, such as Lipiodol.TM. or Lipiodol Ultra Fluid.TM. ethiodol,
or ethiodized oil, which additionally improves viewability, and may
include tungsten powder (see, for example, Suh, D. C., Shi, H. B.,
Park, S. S., Lee, M. S., and Choi, H. Y. 2000. "Change of
Spontaneous Reaction of Glue and Lipiodol Mixture During
Embolization After the Addition of Tungsten Powder: In Vitro
Study," American Journal of Neuroradiology 21(7):1277-1279;
Stoesslein, F., Ditscherlein, G., and Romaniuk, P. A. 1982.
"Experimental Studies on New Liquid Embolization Mixtures
(Histoacryl-lipiodol, Histoacryl-panthopaque)," Cardiovascular and
Interventional Radiology 5(5):264-267; Papo, J., Baratz, M., and
Merimsky, E. 1981. "Infarction of Renal Tumors Using Isobutyl-2
Cyanoacrylate and Lipiodol," American Journal of Roentgenology
137(4):781-785) or a subcorrosive percent of glacial (pure, water
free) acetic (ethanoic) acid (CH.sub.3COOH) (see, for example,
Lieber, B. B., Wakhloo, A. K., Siekmann, R., Gounis, M. J. 2005.
"Acute and Chronic Swine Rete Arteriovenous Malformation Models:
Effect of Ethiodol and Glacial Acetic Acid on Penetration,
Dispersion, and Injection Force of N-butyl 2-cyanoacrylate,"
American Journal of Neuroradiology 26(7):1707-1714; Rosen, R. J.
and Contractor, S. 2004. "The Use of Cyanoacrylate Adhesives in the
Management of Congenital Vascular Malformations," Seminars in
Interventional Radiology 21: 59-66; Gounis, M. J., Lieber, B. B.,
Wakhloo, A. K., Siekmann, R., and Hopkins, L N. 2002. "Effect of
Glacial Acetic Acid and Ethiodized Oil Concentration on
Embolization with N-butyl 2-Cyanoacrylate: An In Vivo
Investigation," American Journal of Neuroradiology 23(6):938-944)
both for enhanced viewability and to retard premature setting as
would clog the delivery line.
[4570] The addition of esterified fatty acid and gold particles
similarly retards polymerization and provides radiopacity (see
Pollak, J. S. and White, R. I. Jr. 2001. "The Use of Cyanoacrylate
Adhesives in Peripheral Embolization," Journal of Vascular and
Interventional Radiology 12(8):907-913). The use of retardants must
always consider the open time of the adhesive during passage
through the delivery line to avoid clogging, following injection
(implantation), as well as the effect these will have on open time
in the proximity of the various components described herein for the
delivery of heat or cold, whether directly to the adhesive, to
tissue, or to a component near to the adhesive.
[4571] Increasing the proportion in the mix of glacial acetic acid
extends cyanoacrylate cement open time reducing the tendency for
the cement delivery line to become clogged, and equally
significant, results in improved tissue penetration, something that
increasing the proportion of the Lipiodol tends to reduce (Lieber
et al. 2005 just cited). Several reviews of surgical adhesives,
tissue sealants, and hemostatic agents are available (see, for
example, Pursifull, N. F. and Morey, A. F. 2007. "Tissue Glues and
Nonsuturing Techniques," Current Opinion in Urology 17(6):396-401;
Evans, L. A. and Morey, A. F. 2006. "Hemostatic Agents and Tissue
Glues in Urologic Injuries and Wound Healing," Urologic Clinics of
North America 33(1):1-12; Traver, M. A. and Assimos, D. G. 2006.
"New Generation Tissue Sealants and Hemostatic Agents: Innovative
Urologic Applications," Reviews in Urology 8(3):104-111; Copeland,
D. C. and Ramakumar, S. 2003. "Tissue Sealants and Hemostats:
Innovative Urologic Applications," Contemporary Urology
15(10)61-73; Baxt, S. 2001. "Tissue Glue," Plastic and
Reconstructive Surgery 107(5):1311-1312). Techniques for hemostasis
in laparoscopic entry as pertinent hereto are likewise available
(see, for example, Lattouf, J. B., Beri, A., Klinger, C. H.,
Jeschke, S., and Janetschek, G. 2007. "Practical Hints for
Hemostasis in Laparoscopic Surgery," Minimally Invasive Therapy and
Allied Technologies 16(1):45-51; Entezari, K., Hoffmann, P., Goris,
M., Peltier, A., and Van Velthoven, R. 2007. "A Review of Currently
Available Vessel Sealing Systems," Minimally Invasive Therapy and
Allied Technologies 16(1):52-57).
[4572] The much stronger bond, much shorter curing time at room
temperature, and acceptable histological disposition of
cyanoacrylate cement (see, for example, Saba, D., Yilmaz, M.,
Yavuz, H., Noyan, S., Avci, B., Ercan, A., Ozkan, H., and Cengiz,
M. 2007. "Sutureless Vascular Anastomoses by N-butyl-2
cyanoacrylate Adhesive: An Experimental Animal Study," European
Surgical Research 2007 39(4):239-244; Kaplan, M., Bozkurt, S., Kut,
M. S., Kullu, S., and Demirtas, M. M. 2004. "Histopathological
Effects of Ethyl 2-cyanoacrylate Tissue Adhesive Following Surgical
Application: An Experimental Study," European Journal of
Cardio-thoracic Surgery 25(2):167-172) as compared to any other
kind of surgical adhesive currently available is desirable for
assuring the sealing of each stay insertion incision before
withdrawal.
[4573] The superior tissue infiltration allowed by an alternative
surgical sealant still or not yet under study (see, for example,
Ozmen, M. M., Ozalp, N., Zulfikaroglu, B., Abbasoglu, L., Kacar,
A., Seckin, S., and Koc, M. 2004. "Histoacryl Blue versus Sutured
Left Colonic Anastomosis: Experimental Study," Australian and New
Zealand Journal of Surgery 74(12):1107-1110), perhaps a
gelatin-resorcinol-formaldehyde-based glue of the kind made by
Cardial, Technopole, Sainte-Etienne, France (see Wippermann, J.,
Konstas, C., Breuer, M., Kosmehl, H., Wahlers, T, and Albes, J. M.
2006. "Long-term Effects in Distal Coronary Anastomoses Using
Different Adhesives in a Porcine Off-pump Model," Journal of
Thoracic and Cardiovascular Surgery 132(2):325-331) that would
better promote the actual mending or union of the connective tissue
as it was replaced might best be taken advantage of instead.
[4574] XV10. Practitioner Preference for Cyanoacrylate Tissue
Sealant
[4575] Small-chain cyanoacrylates absorbed but suspected to be
toxic and long-chain cyanoacrylates considered less toxic but
slowly and not fully absorbed, ongoing work on investigational
atoxic absorbable surgical cyanoacrylate cements seeking complete
atoxicity and absorption may have the effect of further improving
cyanoacrylate cements (see, for example, Schenk, W. G. 3rd,
Spotnitz, W. D., Burks, S. G., Lin, P. H., Bush, R. L., and Lumsden
A. B. 2005. "Absorbable Cyanoacrylate as a Vascular Hemostatic
Sealant: A Preliminary Trial," American Surgeon 71(8):658-661;
Lumsden, A. B. and Heyman, E. R. 2006, cited above Ellman, P. I.,
Brett Reece, T., Maxey, T. S., Tache-Leon, C., Taylor, J. L.,
Spinosa, D. J., Pineros-Fernandez, A. C., Rodeheaver, G. T., and
Kern, J. A. 2005. "Evaluation of An Absorbable Cyanoacrylate
Adhesive as a Suture Line Sealant," Journal of Surgical Research
125(2):161-167; Seifman, B. D., Rubin, M. A., Williams, A. L., and
Wolf, J. S. 2002. "Use of Absorbable Cyanoacrylate Glue to Repair
an Open Cystotomy," Journal of Urology 167(4):1872-1875).
[4576] XVI. Stay Insertion Tools
[4577] Stay insertion tools are shown in FIGS. 87 thru 91, 95, and
102, with internal workings of a mechanical embodiment shown in
greater detail in FIGS. 91, 93, 95, 96 thru 99, 102, and 103. Stay
insertion tools can be produced with different degrees of
automation to control the stay ejection cycle. Except for stay
retention, retraction, and recovery electromagnet 242, most stay
insertion tools are mechanical. In such a substantially mechanical
embodiment, stay retention, retraction, and recovery electromagnet
242, remains unenergized from the instant the operator confirms
that stay 231 has been properly inserted as shown in FIG. 86.
[4578] The operator then releases thumb-ring 244, allowing thumb
plunger-rod spring 245 to return thumb plunger-rod 238 to the
raised position, completing the ejection stroke or phase of the
ejection cycle. Control syringe-configured tools such as shown in
FIGS. 87, 88, 90, and 102, apply force to the stay not as imposed
by the operator but rather as set by the force of spring return
when the thumb is lifted. With any control syringe-configured
embodiment, the operator can use the thumb to restrain thumb
plunger rod 238 from returning under the unimpeded force of spring
245, or can suddenly remove the thumb, allowing thumb plunger rod
238 to return under the force and speed deterimined by spring
245.
[4579] Accordingly, when the force of stay insertion is considered
a significant outcome factor, the restorative force of rod-spring
245 is made adjustable through use of a tool with a calibrated
screw thumb-plunger rod 238 return spring 245 tightener-loosener
that allows translating test values into equivalent spring forces.
Such a screw adjustment typically comprises a knurled knob with
threaded center hole that rotates about and at right angles to the
threaded thumb plunger-rod 238 in FIGS. 87, 88, 90, and 102. To
allow instant access by touch, the knob is usually located between
finger rings 232 and 249 and cap 243. To distinguish between
surface hardness as indicated by indentation and ductus wall or
organ cortex or capsule elasticity requires direct viewability.
[4580] This does not, however, equate to a need for high cost
imaging but rather use of an attached or incorporated angioscope.
With no stays loaded, the calibration measures indentation and
applied force against the tip of the stay ejection blade or tongue
247 for direct translation into the return stay insertion spring
force to be set. Automatic adjustment of the spring tautness in
response to the resistance to penetration found is not incorporated
as adding too much expense. When the adventitia is malacotic, a
blunt blade tip with projection that friction fits in a hole at the
center of the blade fork tip protects against puncture through the
ductus. The calibrated scale is etched to encircle an upward
extension of transparent plastic tool barrel 239 which is notched
to avoid obstruction of thumb-ring 244 when depressed.
[4581] In contrast, a pistol-grip configured tool as shown in FIG.
89 inserts stays under the direct intuitive strength of trigger
pull force exerted by the operator and is unamenable to the
quantifying of this force. The insertion of stays based upon the
quantified results of testing therefore requires infixion by means
of a control syringe-configured stay insertion tool. Because the
placement of stays poses relatively little risk and stay by stay
placement responsive to testing would unduly prolong the procedure,
most stay insertion tools take the quantified results of in situ
tissue testing as addressed below in section XVII entitled Testing
and Tests and use these as an intuitive guide.
[4582] As shown in FIGS. 87, 90, and 91, when thumb-ring 244 is
depressed in the control syringe configured embodiment shown in
FIG. 87, the thumb plunger-rod 238 retracts stay ejection blade or
tongue 247 downward, and except for its tip, down out of ejection
slot 248, allowing stay refill strip or clip 250 advancement spring
251 to seat the next stay 231 in the strip, completing the stay
loading phase of the cycle. Exactitude in the force of stay
insertion rarely critical, the nonquantified or intuitive force of
penetration applied by the operator is almost always satisfactory.
Elimination of the need for testing when allowable and the added
expense of omitting a calibrated return spring screw adjustment
from the tool represent advantages of time and cost over
alternative methods for infixing ductus-intramural implants.
[4583] To gain a clear view of the small field, a cabled lamp,
endoscope, or angioscope, not included in the drawing figures, is
clipped or lashed alongside the tool, as may an excimer laser or
radiofreqency scalpel to expedite dissection or assist in gaining
access to the target ductus or tissue. As may be seen in FIG. 90,
the lower end of stay advancement spring 251 is capped by stay
advancement spring end-cap 277. End-cap 277 is configured to
interface with the uppermost stay in refill strip 250 so as to keep
the strip aligned. To assure that the uppermost or last stay in the
refill strip is advanced flush to the floor of ejection slot 248
even past a moderate angle in a tool with pivot, as addressed below
in the section entitled Stay Insertion Tool with Pivoting Base, the
face of cap 277 where it apposes or nestles the uppermost stay is
elevated.
[4584] The bond used to queue the stays into refill strip or clip
of stays 231, ordinarily provided by dried sugar, is easily broken
with the stays axially rotating at and continuing past the bend to
seat firmly against the floor of ejection slot 248 properly for
ejection. Due to the difficulty in introducing a flexible joint
along thumb plunger-rod 238, a stay insertion tool with a pivotable
base, as addressed below in the section of like title, is not
controlled mechanically. In such an embodiment, except for control
by the operator of the ejection cycle as a whole, the subsidiary
functions encompassed within the ejection cycle are not controlled
by the operator or mechanically but rather by the battery 263 and
damped solenoids under the control of an inmate (embedded)
microcontroller.
[4585] Suitable microcontrollers are available from Microchip
Technology, Atmel, Freescale Semiconductor and Texas Instruments
corporations, for example. Instead of up and down reciprocating
thumb plunger-rod 238 to operate the stay ejection blade 247, a
plunger solenoid in the tool base 257 in FIG. 91 is used to perform
this function, and instead of the internal chain pulley and ratchet
mechanism shown in FIGS. 96 thru 98 to control the tissue cement
air pump 264 piston 233 shown in FIGS. 87, 95 thru 99 and 102 when
the operator rotates thumb-ring 244, a rotary solenoid is used.
When the operator releases thumb-ring 244, plunger-rod 238 rises
under the restorative force of spring 245, pulling stay ejection
blade 247 up through ejection slot 248, ejecting a stay 231,
completing the insertion phase of the cycle.
[4586] Stay insertion tools are precision instruments made to
insert stays of a specific shape and dimensions; the ejection blade
and slot lining are not removable to allow use with stays of
another shape or size. The ejection overall comprehends not only
the stay insertion component but attendant components of
electromagnet control and stay coating tissue cement ejection. In a
tool with inmate microcontroller, these functions are automatically
controlled as well. Once satisfied that the stay 231 has been
properly positioned, the operator releases the ejection control
knob (switch, button), or the upper of the two shown as 262 in
FIGS. 87 and 102.
[4587] When pushed in, the upper control knob sends current from
the battery 263 to stay retention, retraction, and recovery
electromagnet 242. While pushed in, the upper knob is rotated to
vary the current and magnetic strength. When pushed in again, the
knob returns to its undepressed position whereupon the current is
shut off. The lower of the two control knobs works in the same way
to control the magnetic circuit with the polarity reversed. So long
as the magnetic strength need not be adjusted, operation of the
tool is single-handed. While such an embodiment is the least costly
to produce, when the magnetic strength must be adjusted, such a
mechanical embodiment poses the drawbacks of requiring 2-handed
operation and necessitating the coordinated depression and lifting
of thumb-ring 244 with the control of the electromagnet.
[4588] For example, if the field strength is set too high, and/or
the operator withdraws the tool from the insertion site prematurely
so that the cyanoacrylate cement does not cause the stay to adhere
where placed, unless the magnetic force is reduced, the stay could
stick to the end of ejection blade 247 and be unintentionally
retracted despite having been well placed as shown in FIG. 86. If
mispositioned, the magnetic strength is deliberately turned up to
retract the stay, and to reposition the stay in ejection slot 148
for rejection requires that the magnetic strength be set high.
[4589] To negate the need for practicing the coordination required
and to avert the human error to which the criticality of perfect
coordination predisposes, most practical tools incorporate a
microchip controller to coordinate the sending of current to stay
retention, retraction, and recovery electromagnet 242, with the
position of thumb plunger-rod 238 and the ejection blade 247 or the
phase in the ejection cycle. The stay ejection blade 247 retracted,
the stay refill strip 250 advancement spring 251 forces the next
stay 231 in the strip down onto the floor of the ejection slot 248
and in position to be ejected.
[4590] In an embodiment that is mechanical in using only an
electromagnet to generate the magnetic force and not incorporating
an electromechanical actuator in the form of a plunger solenoid,
for example, and therefore without the aid of an embedded
microcontroller to accomplish the action automatically, the
polarity of to stay retention, retraction, and recovery
electromagnet 242, is not ordinarily reversed for a moment after
being retracted to assure that residual magnetization of the
ejection blade 247 does not accumulate in the ejection blade 247 or
cause a stay 231 to adhere to its tip. Instead, a polarity reversal
control knob, the lower of the two knobs shown as 262 in FIGS. 87
and 102 is provided for periodic demagnetization, confirmable by
checking whether the stay ejection blade 247 attracts a loose stay
231 from a table top.
[4591] Demagnetization of the ejection blade 247 is usually
accomplished by reversing the polarity of stay retention,
retraction, and recovery electromagnet 242, the ejection blade 247
representing the terminal component in the magnetic circuit, each
stay 231 added at the end thereof once articulated by the during
insertion. Control of the battery 263 supplying current to stay
retention, retraction, and recovery electromagnet 242 in strength
and polarity is ordinarily controlled manually, but as indicated,
is more often supported by an embedded microcontroller that
automatically adjusts the field strength in coordination with the
ejection cycle. In this instance, the polarity is automatically
reversed for an instant to assure that no buildup of magnetization
takes place.
[4592] In a fully electrified embodiment wherein ejection is
effected by a damped direct current plunger solenoid, power for the
solenoid is taken from the same onboard battery 263, such as
lithium ion, that powers stay retention, retraction, and recovery
electromagnet 242 under the control of the same microchip as
controls the battery component of the ejection cycle. In an
embodiment that ues a solenoid without an embedded microcontroller,
a plunger-rod 238 connects the solenoid positioned down in the tool
base 257 to the inmate stay coating pump piston 233 but not to the
plunger-rod thumb-ring 244, which is stationary rather than
depressed and raised as is that of a syringe.
[4593] With such an embodiment, the field strength set before use,
the operator positions the tool on the ductus, pushes the upper
triggering control knob, and if satisfied that the stay is properly
inserted, pushes the same control knob again to deenergize the
electromagnet and leave the stay as positioned. When the ejection
cycle is under the control of a microcontroller, the
microcontroller adjusts the field strength. Because the auxiliary
syringe is more often used on an intermittent, discretionary basis
to dispense surgical cement or another fluid therapeutic substance
independently of the stay insertion cycle, control over an
auxiliary syringe attachment, as shown in FIGS. 101 thru 103 and
addressed below in the section entitled Stay Insertion-Tool
Auxiliary Syringes, is not usually integrated into the ejection
cycle as an automatic component thereof.
[4594] A switch on thumb-ring 244 allows switching control of an
auxiliary syringe between integrated into or independent of the
ejection cycle. The auxiliary syringe is controlled by depressing
buttons mounted about the outside of thumb-ring 244 as shown in
FIGS. 87, 88, and 102. By contrast, the inmate (normally long chain
cyanoacrylate) cement stay coating air pump 264 comprising piston
233 and cement tissue cement/surgical adhesive-sealant refill
cartridge 236 in refill cartridge compartment 235 shown in FIGS.
87, 88, and 102 with inner workings shown in FIGS. 95 thru 100, is
seldom omitted from the stay ejection cycle. The microchip
coordinates the ejection cycle with respect to both energization of
the electromagnet and the solenoid.
[4595] If the operator is dissatisfied with the insertion, the
ejection control button is not released, the electromagnet is not
turned off, and the spring or solenoid is used to retract the stay.
Since to retract the stay entirely into the ejection slot to its
starting position against the downward force of the stay refill
strip 250 advancement spring 251 as preferred requires considerable
magnetic force, such a semiautomatic embodiment is provided with a
high capacity battery and a powerful electromagnet. The position of
the battery and electromagnet compartments high up on the tool
place these well clear of the entry incision, only the small
working end of the tool and a portion of the shaft needed to reach
down to the ductus introduced intracorporeally.
[4596] The size of the battery and electromagnet are thus limited
only by the need to avoid blocking the sight lines of the operator,
so that these can be made as large as necessary. An aborted and
retracted stay is placed sufficiently to a side of the initial
incision to minimize trauma to the ductus. The ejection blade can
be returned by a spring as in the mechanical embodiment or by
reversal of the solenoid in an electrical embodiment whether by a
solenoid spring return or reversal of polarity.
[4597] Rather than by a direct mechanical connection, a stay
insertion tool with pivoting base, as addressed below in the
section of like title, uses a direct current plunger solenoid to
move the stay ejection blade. Although actuation of the onboard
tissue cement (or other therapeutic fluid) pump is by direct
mechanical connection to the solenoid that pulls up the stay
ejection blade, the level of electrification already incorporated
prompts further incorporation of a microchip to coordinate the
ejection cycle.
[4598] XVI1. Stay Insertion Tool Structure
[4599] Access to the exterior of the ductus wall in order to insert
a stay with a pliers-type tool such as a crile or needle forceps at
the correct angle necessitates a needlessly long incision. A
special stay insertion tool (stay infixion tool, stay inserter)
that allows the wall to be implanted with the tool normal to the
outer surface of the ductus makes insertion possible through a
keyhole incision. Inserting stays from within the lumen with
endoscopic forceps is similar to placing suture with a curved
needle held with a needle forceps where the needle can be
perpendicular to the tool making rotation of the wrist sufficient
to insert the needle laterally.
[4600] When access to the ductus is clear so that the surrounding
tissue does not come in contact with the tool, as in an open
surgical field, the tool will ride up and down with the pulse or
intrinsic motility providing the operator with tactile (tactual,
haptic) cues to the proper moment for insertion. A stay insertion
tool is essentially a stapler-type mechanism arranged vertically,
with ancillary means for coating each stay as it is ejected,
illuminating the treatment site when necessary, and configured to
negotiate a surface that is curved and compliant rather than planar
and hard.
[4601] Whether the stays are ejected mechanically or electrically,
the predominant object in the design of a stay insertion tool is to
minimize the size of the entry wound. Rather than modular or
interchangeable, stay insertion tools are made for common
combinations of stays and cements. Attachment to the stay-insertion
tool of an auxiliary syringe as addressed below in the section
entitled Stay Insertion-Tool Auxiliary Syringes allows use of the
tool as either a stay ejector, syringe, or both without the need to
retract the tool once positioned on the substrate ductus.
[4602] Either or both the inmate cement or stay refill cartridge
chambers can be left empty, or both can be filled and an auxiliary
syringe attached to deliver stays coated with cement or any liquid
or semiliquid therapeutic substance with additional liquid
substances delivered from the auxiliary syringe in any sequence
relative to stay ejection if applicable. Thus, the tool without a
stay refill cartridge inserted can function as a syringe able to
deliver multiple substances. Most stay insertion tools are
mechanical an use an onboard battery to power electrical
components, such as the stay recovery and retraction electromagnet
and a fiberoptic lamp or other electrically powered cabled device
clipped alongside the tool.
[4603] However, mechanical embodiments unable to flex without
introducing costly joints, an alternative solenoid powered
embodiment is described below in the section entitled Stay
Insertion Tool with Pivoting Base. It is considered obvious that
solenoid power need not be reserved for a pivoting model and might
be used in any such tool. While demanding skill, spatial clearance
is afforded without making it necessary to lengthen an incision to
more acutely angle the proximal end of the tool, so that this
lateral approach is more readily accomplished than if the tip of
the tool had to remain substantially normal to the ductus. FIGS. 87
and 88 show a control syringe-configured, while FIG. 89 shows a
pistol-configured stay insertion tool.
[4604] The stay insertion tool ideally has a weight such that when
rested upon the ductus, the tool rides up and down in compliance
with the ductus intrinsic motility without compressing the ductus,
exerting the downward bearing force adequate for implantation. The
variability among ductus especially when diseased and the
difficulty of effecting implantation without the addition of
downward force make this ideal elusive. While both inmate stay and
cement ejection functions might be accomplished electrically, a
mechanical embodiment allows the tool to be provided at less
cost.
[4605] By contrast, unless positioned off to a side, a
supplementary, or auxiliary, syringe, as addressed below in the
section entitled Stay Insertion Tool Auxiliary Syringes, attached
to the tool, such as one containing a two-component tissue sealant,
would interfere with a clear view of the treatment site, which
separation at a distance makes the electrical operation of attached
syringes advantageous. When a cement or medication cartridge is
inserted into the air pump 264 chamber, a push type, or control
syringe configured embodiment stay insertion tool such as that
shown in FIG. 87 can be set to eject a cyanoacrylate cement or a
tissue sealant, for example, upon depression of the thumb-ring 244
and inject the stay 231 when thumb-ring 244 is released.
[4606] Except that the ejection mechanisms of the push or syringe
and the pistol configured stay insertion tools work in reverse, the
internal structure and attachment of auxiliary syringes are
equivalent if not identical. Wheereas the inmate stay ejection and
surgical cement or other fluid or semifluid therapeutic substance
delivery mechanisms are locked together so that use for one or the
other required leaving one of the refill cartridge chambers empty,
attachment of an auxiliary syringe or syringes not only allows
additional therapeutic substancees to be delivered to the treatment
site without the need to retract the tool once positioned on the
substrate ductus, but isolates syringe from ejection function.
[4607] The control syringe configuration of the tool makes it
possible for the operator to extend the interval over which either
or both of these actions last. Additionally, as addressed in the
section below entitled Mechanism for Adjustment in Stay Insertion
Tool Ejection Cycle Inmate Cement Delivery Interval, the moments of
onset, duration, and cutoff of adhesive delivery are adjustableIn
cement-ahead operation, the cement is ejected onto the adventitia
first and the stay is passes through the cement as it enters the
wall of the ductus. Even though most of the cement is wasted or
`squeegeed` away as the stay penetrates, the use of cement or
medication containing a thickener and stays having a deeply
textured surface allows a significant pickup of the cement or
medication.
[4608] A deeply textured surface also assists to conduct heat
through the stay, which expedites bonding with the application of
heat. Tool barrel 239 in which thumb rod 238 is centered and moves
up and down is the stationary body of the tool and runs from just
beneath top cap 243 to toe 253 of foot 255. The tool with adhesive
cartridge 236, air pump piston-plunger 233, tissue cement or
therapeutic fluid delivery line 260 oriented as shown in FIG. 87 is
configured to allow coating the upper surface of each stay.
[4609] As shown in FIGS. 87, 88, 90, 97 99, 102, and 106, with the
exception of tissue sealant (tissue adhesive-hardener) air pump 264
piston-plunger 233, which is connected to and moves with thumb rod
(thumb plunger-rod, plunger-rod, shaft) 238, the parts of the stay
insertion tool seen to the right of thumb plunger-rod or shaft 238
remain stationary, whereas the parts of the tool seen to the left
ride along the outside of the tool barrel or shank 239 down when
the operator depresses, then up when the operator ceases to apply
downward force with his thumb against thumb plunger-rod or shaft
238. The portion of the tool between the ejection control
syringe-type or trigger control at the proximal end or top and the
distal or working end is shank 240, which includes soft iron
magnetic conductor and probe 241.
[4610] To minimize the dimensions of the portion of the tool for
insertion intracorporeally, tool barrel or shank 239 is drawn down
to as low a cross-section as does not impede thumb plunger-rod or
shaft 238. To use the stay insertion tool, the ductus is accessed
through a small incision, which can be held open by retractors,
such as a miniature version of an omni-bearing retractor or a
cannula. The size of the insertion tool necessarily gauged to the
diameter of the ductus to be treated, the distal end of the
insertion tool is typically 5 millimeters wide and 8 millimeters
from front to back. In FIG. 87, cap 243 is not bonded to the
components to the left-hand side of thumb plunger-rod or shaft 238
but is bonded to those on the right-hand side.
[4611] Referring now to FIGS. 90 and 91, parts of the stay
insertion tool beneath cap 243 shown to the left side in FIG. 87
move down when the operator depresses thumb-ring 244 and return
upwards by plunger-rod 238 return spring 245 when thumb-ring 244 is
released. Thus, distal tip of soft iron magnetic conductor and
probe 241 moves up and down with stay retention, retraction, and
recovery electromagnet 242 and heel 246 of stay ejection blade or
tongue 247 as one. In FIGS. 87, 89, and 90, the ductus is 1, its
wall 7, and lumen 8 consistent with FIGS. 2 thru 5 Alternatively,
the distal end of the soft iron magnetic conductor and probe 241
could be slid against an upright contact strip at the back of stay
ejection blade 247, thereby to conduct the magnetic force used to
retain the stay.
[4612] Then the parts of the tool to the left would remain
stationary allowing better depth clearance for the butt portion
behind the foot of the insertion tool base. Devising the mechanism
to present reciprocal movement externally makes it possible to
mount a sliding contact used to control the delivery of a tissue
sealant from an attached dual-chamber syringe. In an embodiment in
which the parts shown to the left are stationary, the sliding
contact is placed along thumb plunger-rod or shaft 238 with the
stationary contact mounted to the internal surface of the tool
barrel or shank 239. Such an internal sliding contact can be
positioned anywhere along thumb plunger-rod or shaft 238. However,
internal location makes the sliding contact inaccessible without
disassembly of the tool.
[4613] While another such internal contact could be used to control
the motorized expulsion of the inmate (internal) surgical cement
syringe that would simplify the reversal of cement delivery between
cement-ahead (of stay ejection) and cement-follow modes of
operation, a relatively simple mechanical system makes it possible
to provide the tool at less expense. When thumb plunger-rod or
shaft 238 is fully depressed, the front end of the ejection tongue
must remain intromittent or threaded within a portion of stay
ejection slot 248 far enough to the rear as not to interfere with
the seating of the next stay to be ejected, and when the thumb
plunger is released, the front end of the ejection tongue must
extend past the front edge of stay ejection slot 248 by the
distance that the trailing tip of the stay is to be countersunk
within the wall of the ductus.
[4614] Thumb plunger-rod or shaft 238, made of a nonmagnetic
stainless steel, such as one of those specified below in the
section entitled Subcutaneous, Suprapleural, and Other
Organ-attachable Clasp- or Patch-magnets, must have reciprocating
travel sufficient to fully retract plunger-blade or stay 231
ejection blade or ejection tongue 247, and when returned by thumb
plunger-rod compression spring 245, drive stay 231 through stay
ejection slot 248 and into ductus 1 wall 7. Since the operator is
able to control the return of thumb plunger-rod 238 under the
restorative force of thumb plunger-rod 238 compression coil spring
245, this spring is chosen for just enough force to allow stay
ejection blade or tongue 247 to penetrate the most resistant
diseased ductus.
[4615] While stays 231 do not extend to the lumen, calcification of
layers through which a stay 231 must pass disallow the use of stays
(or miniballs) and call for resection and anastomosis of the
segment affected thus. Thumb plunger-rod 238 is centered within
tool barrel 239 by attachment to the finger rings above and
ejection blade or tongue 247 below. Shown in FIGS. 87 and 90, Stay
refill clip compartment 250 consists of stay advancement
compression spring 251 which bears down on the clip of stays 231
loaded into stay refill clip compartment 251. The spring circular,
and the stays torpedo in cross section, the spring matches the
stays 231 in length and has a lower end-cap with a circular top and
bottom configured to complement the upper surface of stays 231.
[4616] In a control syringe-configured push-type stay insertion
tool such as shown in FIGS. 87 and 88, which does not allow
switching between cement-ahead and cement-follower operation, the
thumb, index, and middle finger rings all freely rotate about a
vertical axis, a rotary joint (not shown) on level with the bottom
of cap 243 for thumb plunger-rod 238 allowing the upper portion of
thumb plunger-rod 238 to rotate without affecting the lower
portion. This allows maximum comfort and the least fatigue over the
course of longer procedures with minimal displacement of the distal
or working end of the tool for either a right- or left-handed
operator when the operator must switch hands or is forced by the
anatomy to adopt an awkward angle.
[4617] Index finger ring 232 and middle finger ring 249 are
journaled about vertical pins that allow these to be rotated. In an
embodiment of like configuration that does allow switching between
cement-ahead and cement-follower operation, thumb-ring 244
similarly rotates freely through an arc of about 45 degrees to
either side of center without effecting the rotational angle of
thumb plunger-rod 238. Referring now to FIGS. 96, 97, and 98, in
such a switching embodiment, exceeding this arc at either end
causes thumb-ring 244 to rotate thumb plunger-rod or shaft 238
causing rod 238 to click into engagement with the detent just past
each end of the arc.
[4618] This corresponds to the rotation of thumb plunger-rod 238
such that the pin used to switch between sides of sprocket chain
252 is engaged in the sprocket link to one or the other side, which
side determining whether air pump 264 piston-plunger 233 is driven
downward with the thumb plunger-rod in cement-ahead operation or
when thumb plunger-rod 238 is released to return to the top
position under the force of thumb plunger-rod compression spring
245. Matching the strokes of thumb plunger-rod or shaft 238 and
cement or medication air pump 264 piston-plunger 233 eliminates the
need for an additional mechanism for limiting the portion of thumb
rod stroke used to move air pump 264 piston-plunger 233.
[4619] The length of thumb plunger-rod 238 which passes through cap
243 when depressed has a shallow longitudinal groove (running
concavity) or spline-cut that can be rotated between groove
complementary protrusions or elevations on the inside of cap 243. A
r rotary joint above the level of stay ejection blade or tongue 247
allows the lower portion of thumb plunger-rod 238 to remain at a
fixed rotational angle despite first free rotation of thumb-ring
244, then rotation with the thimb ring of thumb plunger-rod or
shaft 238 above the level of the rotary joint.
[4620] To allow the sliding and rotation of a thumb switch or
switches mounted to thumb-ring 244 to any position along thumb-ring
244 for the immediate control of any auxiliary devices in use,
which is addressed in the section below entitled Connection of the
Holding Frame to the Stay Insertion Tool, such as an outrigger
syringe holding frame, laser, or suction line, thumb-ring 244 is
uniform in cross section. Small depressions and its complementary
elevations on the internal circumference of cap 243 (not shown)
serve as detents that allow thumb plunger-rod or shaft 238 to be
positively engaged at the rotational angle of one or the other of
the two ridges; however, the depth of engagement between the
elevations and depressions, or detents, allow rotation to and
detention at either rotational angle with relative ease.
[4621] The free rotation about its longitudinal axis of thumb-ring
244 between these detent protrusions (along with the free
rotatability of the index and middle finger rings 232 and 249) as
addressed below in the section entitled Mechanism for Switching
from Cement-ahead to Cement-follower Operation produces no rotation
of thumb plunger-rod 238. The rear outer surface of stay
refill-strip compartment 250 is concave to complement the front
surface of tool barrel 239 for a flush fit, these two surfaces
bonded together by means of an adhesive such as a cyanoacrylate
cement. The bottom or floor end of stay refill-strip compartment
250 is curved upward from back to front, and the underside of the
stay ejection slot 248 floor is the tool foot, which is deep
textured to resist slippage when set in complementary relation to
the outside of the ductus to be implanted.
[4622] As shown in FIG. 93, the front tip of stay ejection blade or
tongue 247 is indented to engage the rear end of stay 231 and
extends into the rear of stay ejection slot 248 but not into the
chamber within as would obstruct the descent of each stay in the
refill strip or clip of stays 231 in turn down against the floor
under the downward force of stay advancement compression spring
251. When the wall of tool barrel 239 is too thin to assure that
the front tip of stay ejection blade or tongue 247 will be retained
in the correct position to push through each stay 231, a rearward
extension in the form of a lip surrounding stay ejection slot 248
rear is applied by gluing tiny strips of a plastic to form a
framing rearward extension to stay ejection slot 248 opening.
[4623] Each stay in turn is thus constrained to the correct seating
and exit path under the downward force of spring 245 and the sides
of stay refill clip compartment 250. In FIGS. 90 and 91, the
entrance for the stay ejection blade 247 into the stay ejection
slot 248 extends just below the lower edge of the front wall of
tool barrel 239, which is level with the upper suface of the stay
against the lower surface or floor of stay ejection slot 248.
Releasing thumb-ring 244 thus causes the front tip of stay ejection
blade 247 to engage the rear tip of the stay pressed down against
the lower surface or floor of stay ejection slot 248 driving stay
231 through the front opening of ejection slot 248 and into the
outer tunic of ductus wall 7 or adventitia 1 shown in FIGS. 2 thru
5 as 2.
[4624] The downward force exerted by stay advancement compression
spring 251 and complementary contours of the stay body and floor of
stay ejection slot 248 prevent the front stay-engaging end of stay
ejection tongue 247 from applying an ejection slot-deviating or
nonaligned upward angular vector against the rear of stay 231 as
would angle the stay to one side, resulting in resistance to
ejection and nonperpendicular entry into ductus wall 7. Still
referring to FIGS. 90 and 91, in both the push or control injection
syringe-configured embodiment shown in FIGS. 87 and 88 and the pull
or pistol-configured embodiment shown in FIG. 89, magnetic
conductor and probe 241, lower end of thumb plunger-rod or shaft
238, and lower end of ejection tongue 247 are fastened together by
magnetically conductive rivet 258 and spaced apart from one another
along the barrel of rivet 258 by spacing tubes, washers, or
ferrules 259.
[4625] Fastened together thus, magnetic conductor and probe 241
slides up and down against the rear outside wall of stationary tool
barrel 239, the lower end of thumb plunger-rod 238 moves down and
up within and extends below the lower end of tool barrel 239, and
the lower end of ejection tongue 247 extends below the front wall
of the bottom end of tool barrel 239 and stay refill-strip
compartment 250. As best seen in the detail of the tool bottom in
FIG. 91, the bottom portions of these reciprocating parts are
punched or drilled to pass through and joined together by
magnetically conductive rivet 258 with stay ejection tongue 247 at
the front, thumb rod thumb rod 238 at the center, and magnetic
probe 241 at the rear, these three parts separated by spacing
tubes, washers, or ferrules 259 and comprising the rear
reciprocating butt portion 256 of the stay insertion tool.
[4626] Magnetically conductive rivet 258 binds together rear butt
portion 256 of the tool by passing through these parts and through
spacing tubes, washers, or ferrules 259 used to space these parts
apart. Rivet 258 thus includes magnet conductor and probe 241,
spacing tubes, washers, or ferrules 259, and stay ejection tongue
247. Upon depression of thumb rod 238, butt 256 moves up and down
or reciprocally past the stationary bottom or distal margin of tool
barrel 239 and stationary barrel 239 with foot 255 fastened to its
front. In FIGS. 87, 89, and 90, the bottom of the reciprocating
butt portion 256 of base 257 is additionally covered by a
protective pad of surfactant and other tissue irritating material
free neoprene or similar cushioning material.
[4627] If and only if a slitting edge attached beneath a permanent
bottom protective cusion 276 presents no sharp edges, a separate
stay extraction slitting edge as addressed below in the section
entitled Butt-pad with Retractable Slitting Edge may be fitted
flush therebeneath. In a mechanical embodiment, butt 256
reciprocates up and down by the small distance equal to that of
stay ejection blade 247 past the lower border of stationary barrel
239. Use of a vertically reciprocating mechanism allows a smaller
tool diameter and thus entry wound than do rotatory mechanisms that
use a miniature electrical motor and a crank or cam shaft to
convert the rotary to horizontal reciprocation of the ejection
blade.
[4628] The latter allow a rotating vertical shaft with the motion
converting mechanism at the lower or distal end to eject stays at a
very high rate; however, high speed whether fully or semiautomatic
is specifically rejected as militating against the considered
placement of each stay as essential for medical reasons. The
electrically operated tool addressed below in the section entitled
Stay Insertion Tool with Pivoting Base substitutes a plunger
solenoid actuated by a control button on thumb-ring 244 for
vertical reciprocation by depression of thumb-rod 238; however, the
small reciprocal movement of ejection blade 247 remains vertical.
Provided it does not increase the diameter of the tool untenably,
an ejection blade directly connected to a plunger solenoid can
avoid vertical reciprocation.
[4629] However, for stability during and more accurate insertion,
some extension by a butt placed against the proximal circumference
of the target ductus is still provided, although the `butt`
extension is then shorter. To minimize the risk of injury to
adjacent tissue, tool butt 256 is kept as short as practicable
whether reciprocal action is accomplished with or without an
electromechanical actuator. In the mechanical embodiment shown in
FIGS. 87, 90, 91, and 102, foot 255 is rested on the ductus to be
implanted with a stay or stays. Depression of butt 256 retracts
stay ejection blade or tongue 247 to the position just before the
entrance to stay ejection slot 248. The reciprocal action serves to
insert the successive stays.
[4630] This semiautomatic operation whereby each stay is seated for
ejection upon ejection of the stay preceding it reduces procedural
time without the need to withdraw and reinsert the tool increasing
the chances for infection. Except for tools that incorporate a
laterally pivoting foot joint as addressed below in the section of
like title, the orientation of ejection slot 248 is fixed
(nonadjustable). Within the degree of flexion allowed by stay
ejection tongue or blade 247 introducing suitable rotatory joints
would allow stay ejection slot 248 and stay refill strip or clip
compartment 250 to be canted (inclined, angled) from back to front
or side to side; however, this is discounted as needlessly
expensive compared to standardized models.
[4631] Except for its front end portion, forcing thumb-ring 244
downward retracts stay ejection blade 247 from from ejection slot
248, and releasing syringe thumb-ring 244 allows thumb plunger-rod
238 compression spring 245 to retract the lower ends of magnetic
conductor and probe 241, thumb plunger-rod or shaft 238, and
ejection blade or tongue 247, fastened together beneath the lower
end of tool-barrel 239 until these are stopped by the lower end of
tool barrel 239 or slightly short of that height when stay ejection
blade or tongue 247 resists bending or its exact position prevents
the top of the butt from flush relation with the lower end of tool
barrel 239.
[4632] Pushing down on thumb-ring and thus thumb-plunger-rod 238
thus pulls down to withdraw ejection blade or tongue 247 from stay
ejection slot 248, the front end of ejection blade or tongue 247,
as indicated above, always remaining engaged and aligned within
stay ejection slot 248 even when withdrawn to the extent allowed.
The insertion tool must minimally interfere with imaging equipment
needed to confirm satisfactory concentricity of insertion. In the
push-type embodiment described first, the adhesive delivery
mechanism is in line with the stay magazine and the stay retention,
retraction, and recovery electromagnet 242 is situated behind the
tool. Placing both beneath the wrist of the operator resulting in
minimal obstruction to vision and manipulation.
[4633] Provided insertion results in substantial concentricity,
even a suddenness and amplitude of pulse or peristaltic action that
exerts considerable outward compressive force upon a lumen wall
reduced in elasticity by disease will not cause the stay to incise
toward the lumen. The insertion tool must therefore introduce the
stays to be concentric to the ductus. While a growing resistence
posed by adhesive buildup will become apparent tactually, and the
application of adhesive to each stay and proper sealing of each
adventitia entry incision can be seen with the binocular telescopes
and head-lamp when the tool is lifted aside from each stay
insertion site, an endoscope allows proper operation of the tool to
be confirmed without the need for removal.
[4634] The material must also be strong enough that at typically 5
millimeter wide and 8 millimeter from front to back with sides 1.5
millimeter thick, the working end will not fracture or fall inside
the body. In addition to providing transparency, the
nonferromagnetic plastic body serves to prevent interference with
the onboard stay retraction or recall device to be described. For
these reasons, the tool is typically made 18 centimeters or more in
length of transparent polyethylene terephthalate, polystyrene,
high-density polyethylene, or acrylonitrile butadiene styrene.
Methyl methacrylate (acrylic) is too brittle to preclude fracture
at the small working or distal end. Transparent parts tend to
interfere less with views of the work area from different
angles.
[4635] Two embodiments are provided, one, shown in FIG. 87, a
control syringe-configured push-type or passive inserter with thumb
and finger holes that allows the force of insertion to be set by
the restorative force of the plunger or plunger-slide return spring
with force added by the operator if necessary, and a
pistol-configured pull type or active inserter shown in FIG. 89,
which allows the operator to control the force of insertion. In
FIG. 88, thumb 244, index 232, and third or middle finger 249 rings
allows thumb-ring plunger-rod 238 in the push-type to be pulled up
as well as depressed, this representing a key object of
control-type or finger-ring configured syringes.
[4636] Since the stay magazine must queue the stays for contact
with the ductus at the same time that clearance must be allowed for
the ductus itself, a reversed arrangment of the parts as would give
better access to the bottom of the far side of the ductus is ruled
out. Using the embodiments shown, reorientation of the insertion
tool is limited by the dimensions of the incision normal to the
ductus and the attachment of the ductus along its deeper or far
side. In the detail of the tool base shown in FIG. 91, the stay
insertion tool is applied to the ductus at bottom ribbed arcuate
sole 254, which ending in the back at heel 246 and the front at toe
253 must be matched in diameter to the ductus.
[4637] Toe 253, sole 254, and heel 246 comprise the front portion
or foot 255 of tool base 257 situated to front of barrel 239, while
the portion to the rear thereof is butt 256 consisting of tool
barrel 239 and recovery and retraction magnet conductor 241. Foot
255 thus rests as substantially stationary upon ductus 1, while
butt 256 reciprocates between the downward stroke that retracts
stay ejection tongue 247 allowing stay refill strip 250 advancement
spring 251 to force down the next stay 231 into stay ejection slot
248, and the upstroke that causes stay 231 to be ejected under the
restorative force of thumb rod spring 245.
[4638] The surface of insertion tool sole 254 is indented, ribbed,
grooved or covered with small dentate or round pillbox projections
from toe to heel to stabilize the ductus by nonslidably engaging
the stay insertion tool against the surface of ductus 2. Fully
circumferential access requires that the ductus be detachable over
a sufficient segment and sufficiently torsional or twistable
without injury to allow otherwise inaccessible arcs to be
implanted. However, attachment at the far side may serve to retract
the rear wall of the lumen with only the proximate side requiring
retraction by means of a partial stent-jacket. If not and far-side
implantation is necessary, the far side will usually be implantable
endoluminally by means of a barrel-assembly.
[4639] Referring now to FIG. 88, for maximum comfort and minimal
disruption at the working end of the tool during use in any
embodiment of the control syringe push-type whether switchable
between cement-ahead and cement-follower operation, thumb, index,
and middle finger rings of the push-type insertion tool are mounted
for free rotation such that all three rings can, for example, be
rotated by up to 45 degrees clockwise by a right-handed operator or
counterclockwise by a left-handed operator. For minimal
interference with viewability, stay retention, recovery, and
retraction electromagnet 242 with probe extension 241 are placed at
the the side that faces away from the ductus or back of the
tool.
[4640] Allowing sufficient tool length beneath stay retention,
recovery, and retraction electromagnet 242 and surgical cement,
fluid therapeutic, medication, tissue hardener, or fixative tissue
cement/surgical adhesive-sealant refill cartridge 236 in refill
cartridge compartment 235 tends to keep the tool extracorporeal,
reducing the need for a longer incision to achieve entry to the
necessary depth without encroachment upon the edges of the entry
wound. FIG. 91 shows butt 256 and foot 255 portions of tool base
257.
[4641] Placing the index and middle fingers under finger holes 232
and 249 using the thumb to depress thumb-ring 244 and thumb-ring
rod 238 causes compression spring-returned thumb plunger-rod or
shaft 238, which slides through plunger sleeve or tool barrel 239
as in a hypodermic syringe, to retract plunger-blade or tongue 247
from ejection slot 248 to a point behind the queue to clear the way
for the compression spring to seat the next stay from the queue but
with the forward edge of stay ejection tongue or blade 247
remaining inserted within the rearward extension of stay ejection
slot 248, which extends the roof sides, and floor of stay ejection
slot 248 to the rear.
[4642] Stay ejection tongue or blade 247 and stays 231, are
ordinarily inflexible, adjustment in the angle of ejection
requiring the tool as a whole to be tilted or the use of a tool
with a tiltable foot, as addressed below in the section entitled
Stay Insertion Tool with Pivoting Base. Stay ejection tongue or
blade 247 is made of magnetically conductive (ferromagnetic) spring
steel, a polyester coated with flexible ferromagnetic metal, or a
polyester interleaved with ferromagnetic bands or laminations of
flexible ferromagnetic metal. This allows stay ejection tongue 247
to conduct the magnetic force originating in stay retention,
retraction, and recovery electromagnet 242 and passed through
magnetic conductor 241 thence stay ejection tongue 247 to ferrous
core 230 or alternative internal distribution of ferrous content
embedded within stay seen in FIG. 93 as 231.
[4643] This allows the use of polarity and current controls 262
mounted at the side of battery compartment 263 shown in FIGS. 87
and 102 to regulate the magnetic force exerted upon stay 231. By
adjusting magnet controls 262 mounted to the outside of battery
compartment 263, the operator can cause stay ejection tongue or
blade 247 to retain, release, or repel stay 231. This allows the
operator to confirm that stay 231 has been properly inserted within
wall 7 of ductus 1 before proceeding to the next insertion if any.
Thus, a stay that is dropped can be recovered and one that enters
other than true or normal to ductus 1 can be retracted. The
polarity reversing control can be used, for example, to prevent
residual magnetism from holding a stay wished reelased.
[4644] The recall magnetic circuit as shown in FIGS. 87, 90, and 91
thus comprehends stay retention, retraction, and recovery
electromagnet 242, energizing power source (battery) in battery
compartment 263, controls 262, magnetic conductor 241, rivet 258,
and stay ejection tongue 247. Stay ejection tongue 247 is fastened
at its lower or distal rear end by magnetically conductive
(ferromagnetic) rivet 258 to magnetic conductor or probe 241, these
parts comprising butt 256. Heel 246 is bonded to the front at the
bottom of stationary tool barrel 239, and fixes the ejection path
of stay insertion tongue 247. Thumb rod 238 is fastened to and
moves or reciprocates battery in battery compartment 263, stay
retention, retraction, and recovery electromagnet 242, and magnetic
conductor or probe 241 up and down in relation to heel 246 to the
fore.
[4645] To prevent undesired incisions as could result from
involuntary deflection of the tool sideways during insertion, the
front corners of plunger-blade or tongue 247 are blunted or
rounded. So that the front edge of the plunger-blade (addressed
below) engages rather than just abuts upon the back edge of the
stay so that separation of the two would leave the stay
mispositioned or loose, the plunger-blade is thicker than the stays
and v-notched along its front edge to span and encompass the stays.
To accommodate this distinction in thickness, the stays are coated
with freeze-dried sugar that is absorbed and metabolized shortly
after implantation, which process is not significantly impeded by
the cement used to seal the entry incision.
[4646] This retention within the rear portion of the ejection slot
when plunger-blade or tongue 247 is retracted prevents the
plunger-blade from becoming disengaged and misdirected from
ejection slot 248. The front, back, and sides along the path
followed by the stays through the magazine and ejection slot fit
flush to the sides of the stays. In order to countersink the near
edge of the stay once implanted so that it will come to lie beyond
the entry incision through the surface of the ductus sufficient to
prevent backup through the same path and allow placement concentric
as possible, plunger-blade or tongue 247 extends sufficiently down
the side of the ductus and beyond the slight extension of ejection
slot 248.
[4647] A plunger-blade or tongue 247 shield or guard encloses the
exposed portion of plunger-blade or tongue 247 from and thus
prevents displacement or pinching of the ductus 1. The
plunger-blade or tongue 247 shield or guard is continuous with the
floor of ejection slot 248, which is fastened at the bottom to the
sides of stay cartridge by ethyl cyanoacrylate,
2-octylcyanoacrylate, n-butyl cyanoacrylate, or a DYMAX Corporation
200-CTH-series cement and thus remains stationary as plunger-blade
or tongue 247 moves up and down behind it. Withdrawing
plunger-blade or tongue 247 allows stay advancement compression
spring 245 to expand inserting the next stay from the magazine load
queue to be seated on the floor of the ejection slot lining.
[4648] Releasing thumb plunger-rod 238 then causes compression
spring 245 to retract plunger-blade or tongue 247 back up through
ejection slot 248 ejecting stay 231 out the front end of ejection
slot 248. At the forward or exit end, ejection slot 248 beyond the
outer surface of the strip or clip of stays 231 omits the floor of
the ejection slot but preserves the sides and roof The side walls
and roof of the forward extension of ejection slot lining angle
downwards to remain flush to the surface of the ductus. The honed
leading edge of the stay thus emerges from the lining in contact
with the surface of the ductus, and the stay is prevented from
veering aside or upwards before the honed front edge of the stay
penetrates ductus 1.
[4649] The pistol or pistol grip-configured pull-type insertion
tool shown in FIG. 89 has the same stay ejection mechanism as does
the control syringe-configured tool shown in FIGS. 90, 91, and 93
but reverses the action of the insertion tool shown in FIG. 87 by
using plunger-rod compression spring 245 to return trigger 261 to
its forward position, which pulls plunger-blade or tongue 247 up
into ejection slot 248 to eject stay 231. Since it would interfere
with the descent of the next higher stay in the clip from being
advanced (depressed) flush to the bottom of ejection slot 248,
plunger-slide (thumb plunger-rod) 238 cannot be slidably engaged
against the floor of ejection slot 248 by means of a guideway
consisting of either positive or negative side tracks or rails.
[4650] Pulling back trigger 261 then draws plunger-blade or tongue
247 past the entry extension of the walls lining ejection slot 248,
forcing the next stay 231 in the strip or clip of stays out the
front end of stay ejection slot 248. Except for placement of
battery 263 in the pistol grip portion and stay retention,
retraction, and recovery electromagnet 242, of which the tip of
magnetic conductor or probe 241 of stay retention, retraction and
recovery electromagnet 242 must remain in contact with butt 256
rivet 258 during movement, the stay insertion mechanism--to include
ejection slot 248 entry and exit extensions, stay tissue cement or
other therapeutic fluid applicator air pump 264 tissue cement or
other therapeutic fluid supply line (cement feed line, outlow line,
applicator tube) 260, and end tip--is the same as that described
for the control syringe-configured or push-type insertion tool
shown in FIGS. 87, 88, and 102.
[4651] XVI2. Stay Insertion Tool Inmate Stay Recall (Retraction)
and Recovery Electromagnet
[4652] Because the insertion tool is devised to securely hold and
move the stay during the ejection process, mispositioning will more
often be due to operator error in choosing the insertion site than
to malfunctioning of the tool. To allow a mispositioning stay to be
recalled or returned into ejection slot 248 at any point during
insertion prior to withdrawal or the insertion tool, the insertion
tool is provided with inmate stay retention, retraction, and
recovery electromagnet 242. A similar but larger (6 7/16 inches in
length) and less specialized battery-powered electromagnetic probe
241 was described by Crawford, W. A. 1976. "Hand-held
Electromagnet-probe," American Mineralogist 61(1-2):173, available
at hllp://www.minsocam.org/ammin/AM61/AM61_173.pdf.
[4653] Depending upon the length of the tool, any outward bowing of
the soft iron magnet probe 241 is prevented by restraint to its
interface with the tool by means of a longitudinal rail-configured
groove tuning along its back side which in assembly is slid over
one or two complementary undercut projections, essentially railway
track in cross-section, on the probe-facing side of tool barrel
239. Any sticking or excessive friction is prevented by coating
these parts with polytetrafluoroethylene or nylon. Stay recovery
and retraction probe 241 is not held to the side of tool barrel 239
by strapping it about to avoid an accumulation of debris or the
creation of an opportunity for abrasive injury to the margin of the
entry wound or other tissue adjacent to such a strap or straps.
[4654] Stay insertion tool stay retention, retraction, and recovery
electromagnet 242 can be used in either of two ways: a. Normally
on, and b. Normally off: Normally on operation consists of applying
a steady magnetic field, generally of medium strength, throughout
the stay ejection and insertion process. This maintains contact
with the stay at every moment leading up to its acceptable
placement at which time the current from the battery can be turned
off. Maintaining the field up to that point prevents the loss of a
stay in the body cavity and the need to locate it, and also makes
possible its immediate retraction if it should incise or penetrate
the ductus in any manner other than that desired.
[4655] At maximum field strength, it is possible to extract the
stay even when fully implanted; however, the decision to retract is
best made while still in contact with the stay so that it need not
be relocated. Since increasing the field strength is accomplished
in an instant, maintaining the field strength at extraction level
needlessly drains battery 263. Normally off operation consists of
energizing stay retention, retraction, and recovery electromagnet
242 as needed to the field stength appropriate, so that a moderate
current is used to prevent a stay from dropping and high current
used to retrieve a dropped stay or extract a stay that has already
been mispositioned.
[4656] Battery 263, stay retention, retraction, and recovery
electromagnet 242, and soft iron stay retention, retraction, and
recovery electromagnet 242 conductor or core and probe 241 are
connected to and move with thumb plunger-rod or shaft 238. Except
in small sized tools, which use silver wire to generate the same
magnetic field force in less space, stay retention, retraction, and
recovery electromagnet 242 is wound with copper magnet wire. The
armature or core of stay retention, retraction, and recovery
electromagnet 242 extends downward (distad) as magnetic conductor
or probe 241, connected by ferromagnetic (magnetoconductive) rivet
258 that runs through distal working end or base 257 to connect at
its front end to plunger-blade or tongue 247.
[4657] As shown in FIGS. 91 and 92, adhesion of stay 231 within the
notch in the tip of stay ejection blade 247 and the recovery of a
dropped stay or extraction of a stay not properly inserted as shown
in FIG. 86 is obtained by manual adjustment of upper control knob
262 shown in FIGS. 87 and 102, which adjusts the current supplied
by battery 263 through a variable resistor, and therewith, the
magnetomotive force generated, to the field strength required. In
an embodiment that uses an embedded microcontroller to adjust the
magnetic strength at each phase of the ejection cycle, control of
magnetic strength is automated, use of upper knob 262 only required
to override the automatic setting as when a stay must be
retreived.
[4658] Stay retention, retraction, and recovery electromagnet 242
and battery 263 generate sufficient field strength for recovery
without the need for a power supply and socket for connection of
the same as an alternative power source. When rotated, upper knob
262 adjusts a miniature follower arm potentiometer of a kind
obtainable from Placid Industries, Lake Placid, N.Y. that controls
the current drawn from battery 263. For control simplicity and to
reduce the risk of inadvertent actuation or inactivation of stay
recovery and retraction electromagnet 242, rotation of control knob
262 counterclockwise reduces the current down to zero. When not in
use battery 263 is simply removed from its socket within the
battery 263 compartment.
[4659] The instantaneous need to increase the field strength
unpredictable, control of stay retention, retraction, and recovery
electromagnet 242 is never relegated to automatic operation such as
would, for example, shut down the current when stay ejection blade
or tongue 247 begins to withdraw back into its slot. To demagnetize
the probe, the variable resistor current control is turned all the
way down and the polarity momentarily reversed. The stay insertion
tool can be used as a hand-held tractive electromagnet to retrieve
or portative electromagnet to move any small ferromagnetic object
in or out of the body.
[4660] Once implantation is complete, even if the insertion tool
has not yet been removed, extraction is least injurious by incision
and closure with a suitable adhesive, such as butyl 2-cyanoacrylate
or, which consists of a single component or Bioglue.RTM. Surgical
Adhesive (CryoLife, Incorporated, Kennesaw, Ga.), which consists of
two components and must therefore be delivered through an auxiliary
two--the use of an harmonic scalpel avoided as thrombogenic.
Further to allow plunger-blade or tongue 247 to be incorporated
into a magnetic circuit that allows stays which have not inserted
concentrically (misinserted, mispositioned) to be withdrawn, the
parts about the plunger-blade or tongue 247 are formed of
nonferromagnetic material, such as the plastic resins specified
above.
[4661] XVI3. Stay Insertion Tool Inmate Tissue Sealant and/or
Medication Delivery Line
[4662] The stay insertion tool has a built in exit-coating (inmate
tissue sealant and/or medication delivery line (ductus insertion
incision and/or ductus-intramural adhesive-sealant delivery
mechanism, inmate slit-sealer; inmate adhesive applicator) feature
which is usually used to coat surgical cement onto the stays on
exiting but can also be used to coat the stays with any kind of
medication that can be prepared in a semiliquid or paste-like
consistency. As addressed above in the section entitled Stay
Insertion Tools, subsection Structure of Stay Insertion Tools, FIG.
87 shows a stay insertion tool with a built in (integral, inmate)
adhesive (tissue cement, surgical cement), delivery line. This line
can be used to deliver medication or medication mixed into the
tissue cement.
[4663] Such medication includes antibiotics, antispasmodics,
platelet blockers, anticoagulants, anti-inflammatory drugs, and so
on. Medication for dispensing upon stay insertion may require the
addition of a thickening or gelling agent, such as polysorbate 80
or monoglycerides of saturated or unsaturated higher carbon atom
(12 to 20) fatty acids, such as stearic acid, palmitic acid, or
oleic acid. Any use of the inmate tissue cement and/or medication
delivery line can be coordinated with the dispensing of medication
or a sealant from an auxiliary syringe or syringes as introduced
above in the section entitled Administration of Target and
Target-adjacent Implantation Preparatory Substances and addressed
below in the section entitled Powered Stay Insertion Tool Holder
for the Attachment of Medication or Tissue Sealant Syringes Whether
Single, Dual, or Multi-chambered as Supplied, for Tool
Slave-follower or Independent Use.
[4664] As described below in the section entitled Mechanism for
Switching from Cement-ahead to Cement-follower Operation, the
inmate delivery line can be used to coat both or only the upper
surface of each stay with cement or medication. As described below
in the section below entitled Mechanism for Adjustment in Stay
Insertion Tool Ejection Cycle Inmate Cement Delivery Interval, when
set to cement-follower operation, the onset of cement or medication
discharge can be varied to coat the entire upper surface or only a
portion of the trailing end of each stay.
[4665] As addressed above in the section entitled Arcuate
Stent-stays (Stays, Stent-ribs, Ribs) or Stays for Use with
Stent-jackets, stays for such use are usually given a deep surface
texture to reduce the amount of adhesive that is wiped or squeegeed
away when the stay penetrates the outer surface and moves through
the ductus wall. The ability to carry forward a sufficient coating
of adhesive ductus-intramurally can make it possible to apply an
extraluminal stent even when the pre-test described below in the
section entitled In Situ Test upon Endoluminal Approach for Intra-
or Inter-laminar Separation (Delamination) reveals a lack of
cohesion among the layers of the wall that would othewise result in
separation failure.
[4666] For this reason, cement or medication refill cartridge
plunger-plug 234 (not to be confused with inmate cement or
medication delivery line air pump 264 piston-plunger 233), is of
the multiple elastomeric flange kind used in syringes.
Piston-plunger 233 is intermittently driven forward under air
pressure developed through the reciprocal action of the stay
insertion tool, which as explained below, is adapted to provide
integral air pump 264 shown in FIGS. 95 and 102. To reduce off-axis
deflection and jamming of piston-plunger 233 in its channel, the
upper surface of piston-plunger 233 is dished or hollowed out to
concentrate the air pressure at the center.
[4667] The cartridges are individually sealed in sterile envelope
packages and discarded following use. To allow the removal and
insertion of adhesive and solvent flush cartridges, tool cap 243 is
removable from the upper end of the tool and has an elastomer
surround to compression airtight fit. The distal end of tissue
cement/surgical adhesive-sealant refill cartridge 236 in refill
cartridge compartment 235 is pressed onto and punctured by hollow
puncture pin 237, and thumb-ring 244 is depressed until adhesive is
brought to the tip of transparent adhesive delivery line 260, which
filled is referred to as primed or charged.
[4668] Referring now to FIGS. 87, 90, 95, and 102, an inmate
sealant (adhesive) application mechanism for sealing the incision
through the adventitia produced by insertion of the stay eliminates
the need for the alternate insertion and removal of a separate
device through the access incision or cannula. With an inmate
gluing mechanism, the seal can be accomplished as part of the
insertion cycle without the need to relocate each incision. To this
end, the reciprocating configuration of these tools lends
themselves to the operation of air pump 264, which allows the
elimination of numerous mechanical parts.
[4669] The ductus entry incision sealing mechanism consists of
surgical cement, fluid therapeutic, medication, tissue hardener, or
fixative tissue cement/surgical adhesive-sealant refill cartridge
236 in refill cartridge compartment 235, which accepts disposable
surgical adhesive-sealant refill cartridges 236 in refill cartridge
compartment 235. To allow air pump 266 to draw air without
vacuuming cement back up through line 260, reciprocating air pump
266, seen as the upper portion of inmate tissue cement refill
cartridge compartment 264 incorporates one-way or unidirectional
air valve 265.
[4670] Air pump 266 comprises piston-plunger 233, connected to
thumb plunger-rod 238 by tissue cement air pump piston arm or
handle 267 that passes through a longitudinal slot in the side of
the tool barrel 239, and adhesive delivery line or tube 260, which
extends from cartridge puncture pin 237 to a forward extension
overlying ejection slot 248. Sealing of the incision is completed
by lightly pressing down on the insertion tool to tamp down the
incision. Since the stays are significantly countersunk by the
plunger-blade or tongue 247, which is longer, this may require
cocking or inclining the tool forward or axially rotating it full
circle to the opposite side of the ductus.
[4671] To function as a bellows-type air pump 266 without an air
bladder, the longitudinal slot must be airtight. This is
accomplished by molding air pump piston arm or handle 267 as
integral with, and centered in as to appear to pass transversely
through, a sliding cover 268, which extends up and down by half the
length of the slot when air pump piston arm or handle 267 is
positioned half way up or down the slot, and which is convex to the
side facing pump 266 to flush fit against the inside of tube barrel
239. Since the sliding cover is twice as long as the slot, it will
obturate all of the slot whether the arm is all the way up or
down.
[4672] More specifically, as seen in FIG. 95, to prevent air from
escaping through the slot along which tool cement chamber air pump
264 piston arm or handle 267 moves up and down, air pump piston arm
or handle 267 has shorter airtight extensions at either side, an
upward extension that is long enough to cover the upper portion of
the slot when the piston is at its lowest position along the slot,
and a downward extension that is long enough to cover the lower
portion of the slot when air pump 264 piston-plunger 233 is at its
highest position along the slot. Air pump piston arm or handle 267
passes through or is molded as integral with slot cover 268. These
extension thus constitute a sliding slot cover with integral piston
handle.
[4673] For low friction and strength, sliding cover and air pump
piston arm or handle 267 is molded in one piece of nylon or a
polymer especially formulated to make bearings, such as iglide.RTM.
or Drylin.RTM. polymer (not to be confused with the antibiotic of
the same name) obtainable from igus.RTM. Incorporated, East
Providence, R.I. Sliding cover 268 is maintained in a straight up
and down path and held flush to the internal wall of tool barrel
239 so that air is prevented from moving through the underlying
slot by a strong and low friction nylon or iglide.RTM. polymer
frame that overfolds the edges of sliding cover 268 and serves as a
slide-way.
[4674] The extension upward and downward from plunger-rod 239 to
cement air pump piston 233 arm or handle 267, which is vertically
centered on the outer surface (surface flush to the internal
surface of tool barrel 239) of sliding cover 268 also serves to
prevent air pump piston arm or handle 267 from deflecting or
yielding to moment loads that would take piston arm out of
perpendicularity with the central axis of the tool either
vertically or horizontally. In a stay insertion tool capable only
of cement-ahead operation, air pump piston arm or handle 267 is
directly connected to thumb plunger-rod 238.
[4675] In embodiments that are capable of switching from
cement-ahead to cement-follower operation, connection of the
communicating arm with the thumb plunger-rod 238 is not direct but
mediated through sprocket chain 252 that allows the direction up or
down of the inmate cement air pump 264 piston-plunger 233 to be
reversed according to which side of the sprocket chain 252 that
pins extending from the plunger-rod 238 are made to engage. Then
cement air pump 264 piston arm or handle 267 is connected through
tool barrel 239 to sprocket chain 252 used to move air pump
piston-plunger 233 up and down. The operator determines which side
by twisting thumb-ring 244 one way or the other.
[4676] As described below in the section entitled Mechanism for
Adjustment in Stay Insertion Tool Ejection Cycle Inmate Cement
Delivery Interval, to set the height at which air can no longer
escape from inmate cement air pump 266 upper portion of cement
refill cartridge compartment 264, stay insertion tools capable of
cement-follower operation are also equipped with a second slot and
sliding cover. As an adjustable pressure relief valve, this second
slot is airtight only when air pump 264 piston-plunger 233
approaches within the distance from the top of tissue
cement/surgical adhesive-sealant refill cartridge 236 in refill
cartridge compartment 235 at which the upper edge of the sliding
cover has been set to cut off the escape of air thereby initiating
pressurization against the refill cartridge refill plug
plunger.
[4677] The substantially constant temperature and humidity in the
catheter laboratory obviate the need for compensation in the air
pump 264 mechanism. One-way air valve 265 admits a volume of air
into air pump 266 upper portion of cement refill cartridge
compartment 264, the pressure pushing down against air pump 264
piston-plunger 233, forcing refill cartridge 236 plunger-plug 234
downward incrementally with each additional incremental volume of
air. This causes adhesive-sealant or medication refill cartridge
air pump 264 piston-plunger 233 to expel adhesive-sealant within
refill cartridge 236 down delivery tube 260 to the point of
emission poised or positioned just above ejection slot forward
extension 269 in FIG. 90, causing each stay 231 to be coated with
adhesive upon ejection.
[4678] One-way air valve 265 not only serves to keep the pump
airtight during the downstroke but allows piston 233 to freely
return under the force of plunger-rod spring 245 to its elevated
starting position without resistance due to a vacuum created by the
occlusion of tissue cement supply line by cement. Purging of line
260 by means of flushing by connection to a syringe or cleaning
cartfidge containing a solvent is addressed in the sections above
entitled Stays Coated with a Heat-activated (-melted, -denatured)
Tissue Adhesive-Hardener, or Binder-Fixative and that below
entitled Use of Stay Insertion Tool.
[4679] Provided its dimensions allow, attachment alongside the stay
insertion tool of an electrical cautery or harmonic scalpel by
attachment with the clips addressed below in the section entitled
Binding of Lines and Cables Alongside the Stay Insertion Tool is
practicable, as is the attachment of a laser, lamp, or endoscope,
the number of auxiliary cabled devices limited by the size of the
entry portal. Unnecessary complexity is eliminated by allowing the
direction of the air pump 264 piston-plunger 233 to move integrally
with thumb plunger-rod 238 rather than to be reversed by
alternative means such as gears, rack, ratchet, or levers, much
less an electromechanical actuator.
[4680] With cement-ahead operation, the tissue cement or other
fluid therapeutic substance within refill cartridge 236 is thus
caused to discharge during the loading phase of the ejection cycle
when the next stay 231 is seated in ejection slot 248 rather than
during the ejection phase of the tool reciprocating action cycle.
Any excess adhesive applied to the stays is then skimmed or
squeegeed away by the upper lip of the ductus entry incision where
it is easily wiped away if thought consequential or otherwise
desired. Backward displacement of air pump 264 piston-plunger 233
during the stay insertion portion of the cycle exhausts air behind
air pump 264 piston-plunger 233 through pressure equalization or
exhaust one-way valve 235 while drawing air through one-way air
valve 265.
[4681] As shown in FIGS. 87, 95 and 99, the insertion tool inmate
adhesive delivery mechanism consists of integral air pump 264,
chamber for the insertion of adhesive cartridges as described, and
a path for the delivery to the stays upon implantation of adhesive.
As shown in FIG. 90, tissue cement within refill cartridge 236
passes through puncture pin 237 and down cement delivery (supply,
feed) line or tube 260 to its distal terminus 269, overhanging the
outlet of ejection slot 248.
[4682] Fastened along the front of the tool by means of an
adhesive, cement delivery (supply, feed) line or tube 260 is made
of any suitable polymer tubing and continues from adhesive puncture
pin 237 over the top of stay refill strip compartment 250, down
past the front of stay advancement compression spring 251 thence
down the front of stay refill strip compartment 250, where it
reaches down to overhang stay ejection slot 248 as overhang
extension shown as 269 in FIG. 90. Shown in detail in FIG. 87 in
the enlarged inset at the bottom and FIG. 90, which provides a
further enlarged view, the distal tip or adhesive emitting end of
adhesive delivery tube 260 is aligned to and overhangs ejection
slot 248 front extension and in position to coat the upper surface
of each stay with adhesive as each is ejected.
[4683] Forward displacement of air pump 264 piston-plunger 233 in
the stay seating portion of the cycle then forces the air trapped
in air-tight refill cartridge compartment 264 in FIG. 95 between
the front of air pump 264 piston-plunger 233 and the surface of
adhesive cement or medication refill cartridge 236 plunger-plug 234
against tissue cement air pump plunger-piston 233 driving tissue
cement refill cartridge plunger-plug 234 farther down into surgical
cement, fluid therapeutic, medication, tissue hardener, or fixative
refill cartridge compartment 235 causing the equivalent volume of
tissue cement in refill cartridge 236 through adhesive delivery
line 260 and through ejection slot 248 overhanging outlet tip
269.
[4684] Each time air pump 264 piston 233 is retracted, an
additional volume amount of air is introduced through one-way air
valve 265 into air pump 266 upper portion of inmate tissue cement
compartment 264. Thus, air pump 264 piston-plunger 233 is
incremently driven forward by an equivalent distance for each
volume of air added to the air column trapped in air pump 264.
Access to the battery 263, adhesive-sealant cartridge, and stay
refill chambers, of which the interiors are contoured to conform to
and thus secure the refills, is through side entry snap covers of
the kind used to cover the compartment used to contain the
replaceable battery in the back of a pocket calculator, that for
the adhesive cartridge (not shown) requiring to be airtight.
[4685] XVI4. Sealing of Stay Insertion Incisions
[4686] Studies of the efficacy of cyanoacrylate cements for
tissue-tissue and tissue-implant bonding can disagree, such studies
mostly limited to a specific application of a specific
cyanoacrylate cement, with none related to the repair contemplated
herein (see, for example, Halli, R., Joshi, A., Kini, Y., Kharkar,
V., and Hebbale, M. 2012. "Retrospective Analysis of Sutureless
Skin Closure in Cleft Lip Repair," Journal of Craniofacial Surgery
23(1):e40-44; Fortelny, R. H., Petter-Puchner, A. H., Walder, N.,
Mittermayr, R., Ohlinger, W., Heinze, A., and Redl, H. 2007.
"Cyanoacrylate Tissue Sealant Impairs Tissue Integration of
Macroporous Mesh in Experimental Hernia Repair," Surgical Endoscopy
21(10):1781-1785; Paajanen, H., Kossi, J., Silvasti, S., Hulmi, T.,
and Hakala, T. 2011. "Randomized Clinical Trial of Tissue Glue
Versus Absorbable Sutures for Mesh Fixation in Local Anaesthetic
Lichtenstein Hernia Repair," British Journal of Surgery
98(9):1245-1251; Testini, M., Lissidini, G., Poli, E., Gurrado, A.,
Lardo, D., and Piccinni, G. 2010. "A Single-surgeon Randomized
Trial Comparing Sutures, N-butyl-2-cyanoacrylate and Human Fibrin
Glue for Mesh Fixation during Primary Inguinal Hernia Repair,"
Canadian Journal of Surgery 53(3):155-160; Dilege, E., Deveci, U.,
Erbil, Y., Dincca , A., Seven, R., Ozarmagan, S., Mercan, S., and
Barbaros, U. 2010. "N-butyl Cyanoacrylate Versus Conventional
Suturing for Fixation of Meshes in an Incisional Hernia Model,"
Journal of Investigative Surgery 23(5):262-266). Accordingly,
reference to the sealing of stay incisions with a cyanoacrylate
cement rather than a fibrin tissue adhesive, for example, is
exemplary.
[4687] Reviews of the different type adhesives are, however
available (see, for example, Duarte, A. P., Coelho, J. F., Bordado,
J. C., Cidade, M. T., and Gil, M. H. 2011. "Surgical Adhesives:
Systematic Review of the Main Types and Development Forecast,"
Progress in Polymer Science Published online by Elsevier, December
2011; Peng, H. T. and Pang, N. S. 2010. "Novel Wound Sealants:
Biomaterials and Applications," Expert Reviews 7 5): 639-659; Ryou,
M. and Thompson, C. C. 2006. "Tissue Adhesives: A Review,"
Techniques in Gastrointestinal Endoscopy 8(1):33-37).
[4688] When a tissue adhesive-hardener refill cartridge is inserted
into the bottom of inmate cement air pump 264, in FIGS. 95 and 102
the stay insertion tool applies a fluid adhesive, such as Ethicon
Omnex.TM. cyanoacrylate surgical sealant, in cement-ahead
operation, to the outer surface of the ductus before each stay is
ejected, or in cement-follower operation, to a variable length
along the upper surface of each stay as it exits the insertion tool
ejection slot. The means for varying the moment of onset for cement
or medication discharge when the tool is set to cement-follower
operation is described below in the section entitled Mechanism for
Adjustment in Stay Insertion Tool Ejection Cycle Inmate Cement
Delivery Interval.
[4689] The adhesive is used to a. Quickly seal the incision made by
the stay as it passes through the outer surface of and into the
ductus, or the stay insertion incision, and in conjunction with an
encapsulating solid collagen and/or albumin solder adhesive-tissue
hardener that jackets about stays configured thus and remains solid
at room temperature but flows (melts, denatures) when heated, b.
Securely bond the stay between the layers embedding it within the
lumen wall and thus reduce the possibility for 1. Intra- or
inter-laminar separation within the wall of the ductus as would
draw the stay and layers radially outward to the stay toward the
bar magnets about the stent-jacket leaving the lumen unaffected, or
in a nonferromagnetic stay that is not kept under outward radial
tractive force, such as a medication stay, 2. Gradual migration
through penetration adaxially (toward the long axis lumen, inward)
as could eventually lead to intimal perforation if not the entry of
a stay into the lumen before the stay became completely
absorbed.
[4690] The risk for a stay to penetrate into the lumen as the
result of an accidental blow (rather than the intrinsic motility in
the wall of the ductus) varies inversely as the quantity of tissue
intervening between the stays and the exterior. The solid protein
solder is formulated as a cool melt to flow at a temperature lower
than would injure the surrounding tissue. For consistency with and
familiarity to the prior art, the solder can be applied to pores
within a thin membranous coating of an absorbable polymer about the
stay that can release medication as it is absorbed, for example.
Applied as indicated, the exothermy of polymerization and vapor of
cyanoacrylate cement are considered insignificant.
[4691] XVI4a. Cement-Before Insertion (Cement-Ahead Operation)
[4692] Cement-ahead operation is the coating of the ductus to be
stayed with cement just before the stay is ejected through the
cement into the wall of the ductus. To reduce run-away, cements and
medication for such use should be thicker or incrassated and
viscid. The stay thus carries forward cement into the ductus. The
apparatus to be described incorporates mechanical means for
applying cement or any other fluid substance such as medication via
the inmate tissue cement delivery line. Cement-ahead operation with
an attached or auxiliary syringe is achieved by adjusting the
timing of auxiliary syringe discharge relative to the stay ejection
cycle of the tool.
[4693] The wiping away or squeegee effect of the top and bottom
surfaces of the stay as it sweeps past the edges of its adventitial
incision or stay insertion incision as it enters the ductus can be
lessened by using implants that have indentations, ribs, or grooves
and a textured surface that retains and carry forward adhesive.
This is especially advantageous in cement-ahead or cement-before
insertion operation whereby surgical cement is expelled onto the
surface of the ductus just prior to passing the stay through the
adventitia to carry some of the cement forward into the ductus wall
thus reducing the risk of laminar separation under the tractive
force exerted by a magnetic stent-jacket.
[4694] Preliminary tests for quantifying a ductus-intramural
propensity for laminar separation are described below for both
endoluminal (miniball, ballistic) and extraluminal (stay) approach.
Such surfacing also allows increased uptake of adhesive and the
quicker transmission of heat, which is used, for example, to
denature or melt a coating of solid solder adhesive-hardener used
when the wall of the ductus is found by one of the test to be
described as internally weakened. The preparation of anticoagulants
in lyophilized (freeze-dried) form, to include heparin salts such
as heparin lithium, the lithium salt of heparinic acid prepared
using ion-exchange technology from heparin sodium, has long been
practiced for preserving blood (see, for example, Shimizu, A. and
Ichikawa, T. 1986. "Blood Collector," U.S. Pat. No. 4,595,021).
[4695] Lyophilized warfarin sodium is sold as a powder for
intravenous injection following reconstitution. Whether the more
proximate placement of miniballs obtained using machine controlled
discharge imparts a weakening of the intima and media as disposes
toward aneurysmal failure requires study; if so, then the
stent-jacket should be placed in position prior to initiating
discharge, just as it should when aneurysm looms for any reason.
Because the stent-jacket is compliant and the distance slight, that
the magnets act in a bistable way as to abruptly seize or `yank` a
ferromagnetic object when the field strength meets a certain value
does not mean that an extraluminal stent interferes with the normal
motility intrinsic in the ductus wall.
[4696] Essentially, the lumen wall is drawn little, or if
previously occlusive tissue has been ablated, no farther outward
than in normal function and under less and less rapidly changing
force, so that the risks of the media if not the adventitia in
which the miniballs have been implanted intra- or inter-laminarly
separating (delaminating) and of stretching injury are slight. To
be certain that the normal relaxed or quiescent diameter of the
ductus plus any additional diameter that may be needed to achieve
luminal patency over the affected segment is not significantly
exceeded by the internal diameter of the stent-jacket to be
applied, the ductus should be measured with a caliper and the
reading matched to the internal diameter specified on the
stent-jacket package.
[4697] Slightly additional retraction to a larger diameter of the
ductus may sometimes be necessary, but if not kept to the minimum,
will begin to undo the advantage over a nonendoluminal stent of
avoiding interference with the normal function of the smooth
muscle. If the ductus is only temporarily swollen, a stent-jacket
with an expansion insert is used, as described in the section below
entitled Expansion inserts for Tme-discrete Decremental contraction
of stent-jackets, comminutable and Meltable. Nevertheless, in basic
contrast with endoluminal stents, the extraluminal stent will be
more compliant with the intrinsic motility or involuntary smooth
muscle action passing through the wall of the substrate ductus.
[4698] Even when a stenotic condition necessitates retraction to a
wider diameter, a magnetic stent-jacket will yield, albeit with
increased circumferential resistance, to the further expansion of
the ductus, that is, even when owing to the greater magnetic field
strength required, compliance must be somewhat reduced.
Circumferential compliance will be somewhat reduced when the use of
a stent-jacket with expansion insert has incorporated more powerful
magnets. Unless the internal surface of the stent-jacket presents
much friction or the magnets used are strong, the circumferential
mobility of the diffuse outer adventitia and the lesser resistance
of a magnetic field to sidewise deflection should afford some
compliance.
[4699] Absent extenuating circumstances, such as the presence of a
tacky exudate, extravasated blood, or the like, a nonmagnetic
stent-jacket, especially when the internal surface of the base-tube
is low in friction and without a lining as would resist
circumferential displacement or a sliding relation between the
adventitia and internal surface of the base-tube at their interface
can usually move with the walls of the lumen. From the moment of
insertion, the extraluminal stent is immediately and instantly
compliant in a way that a slowly and limitedly shape adaptive
nitinol stent cannot approach.
[4700] Between its longitudinal bars of neodymium lanthanoid, of
which each can be magnetized parallel to their thickness to provide
more than one pole directed radially towards the central axis of
the lumen, the base tubing of an extraluminal stent-jacket can be
slitted, perforated, or slotted to enhance compliance with smooth
muscle action, and perforation or slotting will also serve to
expose the outer surface of the ductus to its normal chemical
environment. Small, delimited, and distantly spaced punctures of
the internal elastic lamina do not represent injury equivalent to
the running dissection of a vessel as the result of balloon
overinflation which can lead to shrinkage, intimal hyperplasia, and
restenosis, and is certainly not equivalent to rupture. Stress
relief afforded by an extraluminal stent (see Berry, et al. 2002,
cited above) is not approachable by an intraluminal stent.
[4701] In contrast to this least initial trauma of endoluminal
stents, the extraluminal stenting to be described requires not only
transluminal access to place an intraductal component
subadventitially, but extraductal entry through a separate incision
or entry wound to allow permural access for placement of an
extraductal component, or stent-jacket. The intraductal component
consists of miniature ferromagnetic balls that implanted
ballistically, produce some tearing and bruising that can result in
inflammation, which is, however, medically manageable and short
lived. The detailed responses of the lumen wall to ballistic
implantation of internal origin are distinct from the form of
injury, edematous swelling, and ensuing inflammation that are seen
following injury to tissue exposed to the environment where dermal
and muscle cells are crushed in depth and many tiny vessels
torn.
[4702] Except where percutaneous access is unavoidable using
conventional means as in the ureters, this situates extraluminal
stenting on the trauma scale as intermediate between intraluminal
stenting and open surgery. Essentially, conventional or
intraluminal stenting trades initial placement with relatively
little trauma but the probability of complications that will
increase in severity over time for short-term inflammation as the
result of some cell-crushing, tearing and bruising, edematous
swelling, in larger vessels, some vasa vasorum bleeding, and the
need for an arteriotomy to place the stent-jacket, but thereafter,
as with high-quality dental restorations, relative freedom from
long-term complications.
[4703] In fact, just as might the methods described herein,
conventional methods occasionally result in unpredictable injury
and adverse sequelae, no procedure known being capable of avoiding
this prospect. Since medical surveillance is close while the
patient is still in the hospital and immediately following
discharge, the earlier unavoidable sequelae appear, the more will
there be the opportunity for successful management. In addition to
the administration of a systemic platelet blocker or anticoagulant,
miniballs may have to be wetted or coated with such medication;
however, continued irritation from an endoluminal stent will not
follow, so that such medication can soon be discontinued.
[4704] Introduced from outside the vessel, stays avoid the lumen
entirely, making platelet blockade or an anticoagulant unnecessary.
In blood vessels, the introduction of multiple punctures into the
media is more thrombogenic than are an angioplasty and the
insertion of an endoluminal stent. The apparatus and methods
described herein are applicable to ductus other than vascular, but
the risk of thrombogenesis pertains to blood vessels. Nevertheless,
when access to the outer surface of an artery would necessitate
much dissection or the extension of disease does not permit using
the slower process of inserting stays, miniballs are implanted
quickly with a barrel-assembly.
[4705] This applies whether the implants are to remain permanently
or temporarily; it is necessary to distinguish between the
extraction and the complete removal from the body of implants. As
noted above, the apparatus allows the use of radioactive implants
on a temporary basis. These must not merely be extracted from the
implantation site but removed from the body entirely. The same may
apply to erroneously placed medication miniballs.
[4706] XVI4b. Sealant Cartridges and Sealants (Adhesives)
[4707] This section will address adhesive or sealant cartridges for
insertion into stay insertion tools. An auxiliary adapter for
attaching an additional commercial dual or other multichamber
(multicompartmental) syringe alongside the tool is described below
in the section entitled Powered Stay Insertion Tool Holder for the
Attachment of Medication or Tissue Sealant Syringes Whether Single,
Dual, or Multi-chambered as Supplied for Tool Slave-follower or
Independent Use. As shown in FIG. 87, the disposable refill
cartridges or capsules 236 combine features of disposable
hypodermic syringes, refill tubes used in caulking and greasing
guns, and airgun CO.sub.2 canisters (cartridges, `pistolets,`
`powerlets`).
[4708] Cement refill cartridges 236 are essentially shortened and
miniaturized caulk tubes that are punctured at the outflow end by
means of hollow hypodermic type needle type puncture pin or needle
237 fixed in position at the bottom or distal end of the adhesive
refill chamber. FIG. 87 shows a single glue column for a
single-component adhesive, which pending the availability of fully
absorbed cyanoacrylate-based cements, is preferably
octyl-cyanoacrylate or N-butyl-2-cyanoacrylate cement, if not a
longer chain acrylate cement. Long-chain cyanoacrylate cements have
the advantages of consisting of a single component, which makes the
use of the single puncture needle 237 possible and providing
significantly greater bond strength than any other type of
adhesive.
[4709] XVI4c. Mechanism for Adjustment in Stay Insertion Tool
Ejection Cycle Inmate Cement Delivery Interval
[4710] The initiation and duration or interval in the stay ejection
cycle during which the adhesive is ejected can be adjusted to coat
only the trailing end of each stay, so that only the incision
through which the stay entered the ductus will receive glue, or to
coat the entire upper (convex) surface of each stay as it is
ejected from the insertion tool. The latter is used when it will
serve the better to bond the stay and the layers embedding it
together or when the heat to denature a solid protein solder would
best be avoided, except that owing to a propensity toward
separation among the layers in the ductus wall, additional
cyanoacrylate cement is essential to compensate for this
omission.
[4711] In connection with adjustment in the interval and timing of
sealant ejection relative to magnetic stent stay ejection and
cement-follower operation, the fact that the adhesive has not set
when the stent-jacket is later placed is inconsequential. Adhesives
that set before the stent-jacket can be placed should not be
permitted to present a protrusive contour, however. For this
reason, quick-setting adhesives should routinely be smoothed flush
to the adventitial surface while still fluid. The same applies to
the use of any adhesive, such as one applied with the aid of an
auxiliary syringe as is described below. Turning now to FIG. 95,
one-way or check air intake valve 265 will allow air to move only
into adhesive air pump 266 in the upper portion of cement refill
cartridge compartment 264 when cement or medication air pump
piston-plunger 233 ascends.
[4712] Unless it is preferred to use air pump 266 piston 233 as a
one-way intake valve that allows blow-by about its periphery upon
ascending analogous to the unidirrectional compression seen in a
bicycle tire air pump piston, the fit within adhesive air pump
cylinder constituting the portion of compartment 266 beneath cement
piston plunger 233 of cement or medication air pump piston-plunger
233 is airtight. When the operator pushes down on thumb-ring 244,
air pump piston-plunger 233 is pushed down, causing the pressure
built up in adhesive air pump cylinder constituting compartment 266
beneath cement piston plunger 233 to be channeled through cement
refill cartridge puncture pin 237 forcing adhesive or other fluid
236 down tissue cement or therapeutic fluid delivery line 260 and
out at its lower end overhang 269 just above stay ejection slot
248.
[4713] Thus, to coat a stay over its upper surface, one-way air
intake valve 265 is closed throughout the pressurized downstroke of
the stay loading phase or stroke of the ejection cycle and open on
the spring-return of air pump piston-plunger 233 during the
upstroke or ejection phase of the cycle. Still referring to FIG.
95, the excursion (stroke, displacement) of pump piston 233 fixed
as part of the ejection mechanism, the cement delivery interval is
made adjustable by placing the aperture of one-way air intake valve
265 at the center of A vertically oriented sliding panel or slot
cover 273. To prevent air from leaking out of the pump 266
compartment while the volume is adjusted, sliding panel or slot
cover 273 has upward and downward extensions that cover over
portions of the slot that would otherwise be open to the
outside.
[4714] Sliding slot cover 273 is mounted on the outside of the
upper portion of tissue cement refill cartridge compartment 264 air
pump 266 so as to slide up and down along a vertical way. Sliding
extensions 268 of pump piston 233 and one-way air intake valve 265
function independently and cannot be combined, a valve positioned
thus inaccessible to the operator or outside air. One-way air
intake valve 265 hole-slide 273 moves over a vertical slot in the
side wall of adhesive air pump cylinder 266 and thus prevents any
buildup of pressure against the top of surgical cement, fluid
therapeutic, medication, tissue hardener, or fixative cement
plunger plug 234 until air pump piston-plunger 233 has descended
alongside the hole to cover it over, at which level the air within
the cylinder begins to be compressed as piston-plunger 233 and
tissue cement refill cartridge plunger-plug 234 continues to travel
downwards.
[4715] The moment of onset and duration within the insertion tool
cycle that pressure is applied to surgical cement, fluid
therapeutic, medication, tissue hardener, or fixative refill
cartridge compartment 235 piston-plug 234 and adhesive continues to
be ejected can thus be varied according to how high up the side
wall of inmate cement air pump cylinder or compartment 266 side
hole 265 is slid. As other sliding controls herein to include that
incorporated into the valve body of airguns, one-way air valve 265
in vertically oriented sliding panel or slot cover 273 is
calibrated or graduated to allow precisely repeatable settings.
[4716] An isolated hole for the purpose of coating only the
trailing end of each stay as it ejected through ejection slot 248
would require inordinate precision increasing the cost to provide
the tool, whereas incorporating a slidable cover over a much
elongated hole or slot contributes not only `trimmer` adjustability
for such use but equally important, allows the extent of the upper
surface of each stay to receive adhesive to be varied. Accordingly,
slidable slot cover 273 is similar in conformation to that
incorporated into the valve body of the airgun for adjusting the
exit velocity seen in FIG. 47 but smaller.
[4717] The airtight sliding slot cover is oriented so that the slot
is progressively covered (obturated) moving upwards, in which case
only the rear tip of each stay will receive cement. By continuing
to move air valve 265 in vertically oriented sliding panel or slot
cover 273 upwards, the length of piston stroke downward through
cement air pump or air pressure cylinder 266 until the piston
covers the side opening to prevent the escape of air is reduced,
thus initiating the imposition of pressure on puncture pin 237
earlier in the insertion tool ejection cycle.
[4718] The cement is thus caused to cover each stay as it is
ejected beginning at a distance along the stay that is at or more
closely toward its forward (leading, incisive) end. Pushing down
the sliding slot cover reduces the adhesive ejection portion of the
stoke. When pushed all the way down, the ejection of adhesive is
limited to the trailing tip of each stay. To avoid the use of an
adhesive entirely, the adhesive cartridge is not inserted into the
tool or is removed at the point in the procedure where the use of
adhesive is no longer desired.
[4719] XVI4d. Control Over the Quantity of Fluid Discharged
[4720] The mechanism described above for adjusting the length of
the stroke from the bottom up to the point along the chamber where
the sliding hole one way intake and exhaust air valve 265 is placed
to initiate pressurization and the discharge of contents from the
chamber when the piston descends past this point not only satisfies
the requirement for a volume or quantity control, but effects
discharge with the timing preferred. Specifically, in cement-ahead
operation, during which the cement or medication is emitted during
the downstroke of thumb plunger-rod 238, to make the quantity of
substance emitted dependent upon the height of the closing segment
of the stroke results in the less than full stroke amount of cement
or medication being delivered toward the end of the stroke
minimizing run-away.
[4721] In cement-follower operation, during which the cement or
medication is emitted during the return of thumb plunger-rod 238 to
its undepressed or starting position, setting the initiation of
pressurization closer and closer to the end of the stroke results
in the deposition of cement or medication in correspondingly
smaller and smaller amounts and closer and closer to the trailing
tip of the stay. Set to the lowest point, the least cement or
medication will be deposited to seal the insertion incision made by
the stay upon entering the ductus. Since the trailing tip will be
the primary if not the only target for the deposition of cement,
that in cement-ahead operation the mechanism cannot deposit cement
farther ahead onto the upper surface of the stay while omitting
cement at the trailing tip is not disadvantageous. There would
appear never to be a reason for coating only portions of the stay
ahead of the trailing tip.
[4722] XVI4e. Mechanism for Switching from Cement-Ahead to
Cement-Follower Operation
[4723] Referring now to FIGS. 97 thru 99, in a stay insertion tool
embodiment that is capable only of cement-ahead or cement-follower
operation but not switchable between the two, air pump piston arm
or handle 267 of stay insertion tool inmate sealant or medication
delivery system air pump piston-plunger 233 is directly connected
to thumb plunger-rod 238 with the piston starting position at the
top of the cylinder (cement chamber) so that cement is emitted on
the downstrokes before stay ejection or on the spring returned
upstrokes during ejection respectively. In an embodiment that
allows switching between these two modes of operation, the piston
starting position is midway along the stroke.
[4724] Still referring to FIGS. 97 thru 99, the ability to switch
between cement-ahead and cement-follower operation is obtained
through the interposition between thumb plunger-rod 238 and air
pump piston-plunger 233 of a direction-reversing rope
ladder-configured sprocket chain 252 made of a tough and inflexible
bearing polymer, such as polyoxymethylene homo (DuPont Delrin.RTM.)
or copolymer (Korea Engineering Plastics Company Kepital.RTM.,
Celanese Corporation Celcon.RTM. and Hostaform.RTM., or Mitsubishi
Engineering-Plastics Lupital.RTM., engineering grade polyacetal
resins available from many firms under many tradenames) which
determines whether depressing thumb plunger-rod 238 will drive air
pump piston-plunger 233 upwards or downwards. Inmate tissue cement
air pump 266 piston 233, shown in detail in FIG. 95 and in situ in
FIGS. 87 and 102, is permanently fastened to one run of sprocket
chain 252 by air pump piston arm or handle 267.
[4725] Connection of sprocket chain 252 to thumb plunger-rod 238 is
by sprocket chain engagement arm 272, such that rotating thumb-ring
244 with thumb plunger-rod 238 and sprocket chain engagement arm
272 through 360 degrees rotates sprocket engagement arm 272 to
engage the opposite run of sprocket chain 252, so that inmate
tissue cement air pump piston 233 is raised or lowered accordingly,
whereas rotating thumb-ring 244 180 degrees to the center position
disengages thumb plunger-rod 238 from sprocket chain 252, disabling
inmate tissue cement air pump 264. Sprocket chain or belt
engagement arm 272 is permanently fastened to, and therefore rises,
descends, and rotates with thumb-ring 244 and thumb plunger-rod
238.
[4726] Shown in FIGS. 96 and 97, sprocket chain engagement arm 272
engages sprocket chain 252 at either end of a tee or perpendicular
cross-piece at its distal end, or that end facing sprocket chain
252, only when thumb-ring 244 and thumb plunger-rod 238 are fully
rotated either clockwise or counterclockwise, the pointed ends of
the cross-piece then fitting into spaces separating consecutive
rungs in sprocket chain 252. Unless engaged by rotation of
thumb-ring 244 and thumb plunger-rod 238, sprocket to air pump
piston 233 arm or handle 267 and sprocket chain 252 remain
motionless, inmate stay tissue cement coating air pump then
disconnected from thumb plunger-rod 238 and therefore disabled.
[4727] Sprocket chain engagement arm 272 with distal tee
cross-piece is preferably machined, cast, or die-cut in one piece.
Alternatively, the end tee cross-piece can be a hard fine rod or
wire passed through or fastened toward or at the distal end of arm
272. Rotating thumb-ring 244 and thumb-rod 238 clockwise or
counterclockwise through 360 degrees thus thus rotates sprocket
chain engagement arm 272 so that it engages switches engagement of
arm 272 between the oppositely directed runs of sprocket chain 252,
thus driving sprocket chain 252 either up or down and reversing the
direction of inmate tissue cement air pump piston 233.
[4728] Thus, the operator determines whether the direction of air
pump piston-plunger 233 will be upwards or downwards by rotating
thumb-ring 244 beyond its freely rotated arc to either side
(clockwise or counterwise), and in so doing, determines which side
of sprocket chain 252 will be engaged and driven downward by thumb
plunger-rod 238, by intromission into the right or left sprocket
run of either the right or left tip of the upper cross-piece of
tee-configured sprocket belt engagement arm 272 that extends from
thumb plunger-rod 238. To this end, air pump piston 233 arm or
handle 267 is permanently fastened to one side of sprocket chain
252, this junction being inflexible and the run of sprocket chain
252 used centered on air pump piston 233 arm or handle 267.
[4729] Unless the tool is unusually long, thumb plunger-rod 238
remains centered within tool barrel 239 by its connections above
and below. If necessary, intervening spacing washers or ferrules
bonded about their circumference to the internal surface of tool
barrel 239 are used to center thumb plunger-rod 238. Upper sprocket
wheel 270 and lower sprocket wheel 271 are made of a strong and low
friction polymer used to make bearings, such as iglide.RTM. or
Drylin,.RTM. obtainable from igus.RTM. Incorporated, East
Providence, R.I. or nylon. Sliding air valve 265 sliding panel or
slot cover 273 as such is identical to that used in an embodiment
which is incapable of switching between cement-ahead and cement
follower operation.
[4730] However, air pump piston arm or handle 267 is not attached
directly to thumb plunger-rod 238 but instead fastened to sprocket
chain 252, which can be engaged by thumb plunger-rod 238 on its run
at either side. Relating this action to switching between cement or
following operation, the rotational angles of the two detent ridges
beyond the ends of the free rotation of thumb-ring 244 are the same
as the angles at which either side-looking point facing out from
the end of sprocket chain communicating arm 272 engages the run of
sprocket chain 252 to either side.
[4731] As indicated, rotating thumb-ring 244 clockwise as seen from
above thus rotates thumb plunger-rod 238 and air pump piston arm or
handle 267 causing the right-hand extension of piston arm 267 to
engage the right-hand run of sprocket chain 252, which moving in
the same direction as thumb plunger-rod 238 causes cement air pump
piston-plunger 233 to descend in cement-ahead mode. Rotating
thumb-ring 244 in the opposite direction causes air pump piston arm
267 to engage the rising run of sprocket chain 252 so that thumb
plunger-rod 238 and air pump piston-plunger 233 move in opposite
directions in cement-follow mode.
[4732] That is, when the side or run of sprocket chain 252, to
which piston arm 267 is permanently fastened, is engaged by either
side-looking point facing out from the end of sprocket chain
communicating arm 272, which is permanently fastened to thumb
plunger-rod 238, downstroke of thumb plunger-rod 238 moves air pump
piston-plunger 233 downwards, resulting in cement-ahead operation.
When either side-looking point facing out from the end of sprocket
chain communicating arm 272 engages the sprocket chain 252 at the
other side, downstroke of thumb plunger-rod 238 moves air pump
piston-plunger 233 upwards, so that it the air in cement air pump
264 is pressurized when the operator releases downward force on
thumb plunger-rod 238, which then returns to its raised position
under the restorative force of thumb rod return compression spring
245.
[4733] As shown in FIGS. 97, 98, and 99, upper sprocket wheel 270
and lower sprocket wheel 271 are securely anchored to the inner
wall of tool barrel 239, one above the upper reach of the upward
extension of one-way air valve sliding slot cover 273 and the other
below the lower reach of the downward extension. During ejection of
refill cartridge 235, air pump piston 233 is resisted by the
friction posed by cement refill cartridge plug-piston 234, the
resistance to outflow imposed by the small aperture of puncture pin
237, and the small diameter of cement feed or supply line 260. To
resist moment loads that would lever and break off or jam air pump
piston 233 under this resistance, air pump piston arm 267 is kept
short and the attachments of arm 267 to sprocket chain 252 and air
pump piston arm 267 made strong and rigid.
[4734] The permanent connection between cement air pump air pump
piston-plunger 233 and its side of sprocket chain 252 must be rigid
to minimize nonperpendicular movement of air pump piston-plunger
233 as could result in seizing against the sides of cement
compartment 264. Upper sprocket wheel 270 and lower sprocket wheel
271 are accordingly offset to the same side. Rather than using a
separate ferrule spacer, upper sprocket wheel 270 and lower
sprocket wheel 271 have integral hubs that axially extend from the
rear of each sprocket wheel 270 and 271 to the inner wall of tool
barrel 239. The spacing afforded by these hubs prevent the teeth of
sprocket wheels 270 and 271 from coming into contact with the
internal surface of tool barrel 239.
[4735] Sprocket wheels 270 and 271 are fastened to tool barrel 239
by means of nonmagnetic stainless steel wide-head rivets 274 and
275 shown in FIG. 96 that serve as axles. Made of a metal or
plastic, tool barrel 239 must be sufficiently thick and tough to
secure rivets 274 and 275, which can be countersunk flush to the
outer surface of tool barrel 239. Which side of sprocket chain 252
moves up and which down is arbitrary, but for uniformity, that to
the left can be chosen for downward movement along with thumb
plunger-rod 238 and thus cement-ahead operation. The
counterclockwise detent reached by twisting thumb-ring 244 to
engage the left hand run of sprocket chain 252 is indicated by
engraving or embossing cap 243 with a tick-mark labeled "C-A" for
cement-ahead operation.
[4736] For smooth movement as well as airtightness, cement or
medication air pump piston-plunger 233 has a surrounding
elastomeric annulus. To minimize tool girth and therewith the
length of the incisions required to insert an insertion tool of
given length to its maximum intracorporeal depth as well as to
stabilize and reduce play in the sprocket belt 252 and the parts
that engage sprocket chain 252, tool barrel 239 is the smallest
diameter that allows sprocket chain 252 free movement. Below the
upper segment that accommodates the foregoing mechanism, the
diameter of tool barrel 239 is reduced to serve as a sleeve for the
reciprocal movement of thumb plunger-rod 238.
[4737] The mechanism for adjusting the moment of cement ejection
onset and duration is described above in the section entitled
Mechanism for Adjustment in Stay Insertion Tool Ejection Cycle
Inmate Cement Delivery Interval. Accordingly, by rotating
thumb-ring 244 from one rotatory detent position to the other, the
direction as up or down of cement air pump piston-plunger (cement
piston, cement pressurization piston) 233 upon depression of
thumb-ring 244 and thumb plunger-rod 238 is reversed allowing
immediate conversion from cement-ahead to cement-follower
operation, which is addressed above in the section entitled
Cement-before Insertion or Cement-ahead Operation.
[4738] Upon the release of downward force by the operator of
thumb-ring 244, compression spring 245 returns thumb rod or shaft
238 to the top stop position. If the restorative force encounters a
condition of adventitial sclerosis, the operator forcibly pulls up
his thumb against the superjacent (upper, overlying) arc of
thumb-ring 244. So that a stay may continue to be recalled
(retrieved, retracted, recovered) at any moment preceding its
satisfactory placement, stay retention, retraction, and recovery
electromagnet 242 conductor or probe 241 must remain in contact
with heel 246 of stay ejection blade or tongue 247.
[4739] Thus, whereas the top of battery and magnet in stay
retention, retraction, and recovery electromagnet 242 compartment
to the left moves down and up in relation to cap 243 at the top of
its run, the top of adhesive compartment 235 is affixed to cap 243.
It does this by releasing cement onto the ductus when stay ejection
blade or tongue 247, viewable in FIGS. 90 and 91, is drawn out from
ejection slot 248 just before thumb rod or thumb plunger-rod 238 is
released, allowing stay refill strip advancement compression spring
245 to draw stay ejection blade 247 up through ejection slot 248,
thereby driving the next stay in stay refill strip or clip 250 into
ductus 1.
[4740] By setting cement ejection to a slight interval before each
stay is ejected, some is deposited on the adventitia so that the
stay is coated on its underside. When the cement delivery system is
configured thus, the adhesive interval adjustment described below
in the section entitled Mechanism for Adjustment in Stay Insertion
Tool Ejection Cycle Inmate Cement Delivery Interval is used to
adjust the amount of cement applied to the outer surface of the
ductus. By contrast, the configuration, hence, operation of the
inverted cement delivery system incorporated in the embodiment of
FIG. 89 is the reverse of that shown in FIGS. 90; 91, 95, and 102,
in that cement is ejected when thumb plunger-rod 238 is returned to
the raised position, retracting rather than advancing ejection
blade 247 through ejection slot 248.
[4741] Cement delivery by the cement air pump mechanism in a
pistol-configured embodiment may accordingly be characterized as a
cement-ahead system, whereas that provided by the control
syringe-configured embodiment shown in FIGS. 87, 90, 95, and 102 is
a cement-follower system. Accordingly, unless the adhesive interval
adjustment described above is used to forestall the initiation of
cement outflow, cement will eject in synchrony with the ejection of
stay 231, that is, throughout the interval that stay 231 continues
to eject. The adhesive interval adjustment described below thus
allows the detention of cement delivery onto a rearward extent of
the upper surface of each stay 231, which extent is variable.
Reversed operation expels cement only during stay ejection.
[4742] The mechanism described below in the section entitled
Mechanism for Adjustment in Stay Insertion Tool Ejection Cycle
Inmate Cement Delivery Interval is intended to allow adjustment in
the moment in the tool operational cycle for the start and duration
of cement delivery. With cement-ahead operation, stay 231 is
inserted subadventitially into ductus 1 by pointed incision through
the predeposited cement or tissue adhesive-hardener. Much of the
cement is squeegeed away, but a thin coating is carried forward
into the ductus. For an airtight fit within adhesive air pump 264,
adhesive air pump piston-plunger 233 has an elastomeric surrounding
annulus. While the use of a one-way air valve is specified below,
this annulus could itself serve as a one-way air valve in the
manner of that used in a bicycle tire air pump.
[4743] XVI5. Stay Insertion Tool with Pivoting Base
[4744] Except in an exposed field opened for a primary purpose, the
entry or access incision for insertion of the tool is made as small
and parallel to the ductus to be treated as practicable. The
initial breach of the integument represents the substantive
systemic immune stimulant, extension of the incision or the
addition of incisions imparting additional trauma. To assure true
concentricity or normal alignment of stay insertion
subadventitially or medially, stay insertion tools are made with
parts rigidly assembled. To alter the angle of insertion, a tool
without a joint or pivot such as a gimbal or lateral hinge or
folding joint must be tilted to a side, or forward, or backward,
and/or rotated, as a whole.
[4745] However, a ductus may veer, deviate, or plunge at an angle
that exceeds the degree to which the tool can be tilted to achieve
normal (perpendicular, rectilinear) access. However, if the tool
incorporates a point of flexion or joint, expansion of the entry
incision to properly dispose the tool in relation to the ductus can
often be avoided. That is, when the rectilinear apposition required
to allow circumferential insertion cannot be achieved without
lengthening the access incision and to do so would best if not
necessarily be avoided, a special stay insertion tool with pivoting
base is provided. Referring now to FIG. 91, the downward extension
of tool butt 256 below the level of tool barrel 239 and ejection
slot 248 affords adequate leverage moments to flex or abduct the
tip by nudging it to a side.
[4746] The insertion of a probe alongside any insertion tool should
not be necessary, all parts of butt 257 that come into contact with
neighboring tissue rounded and smooth. When the tool incorporates
an end-pivot as may necessitate pushing the distal end or working
end aganst neighboring tissue to adjust the angle, use in
especially vulnerable sites, such as a vascular bed, is with the
butt additionally padded. Ordinarily unnecessary, a protective pad
seen as 276 in the inset to FIG. 87 and in FIGS. 89 and 90 may be
attached to the bottom of butt by pressing it onto the bottom of
the tool. The pad is permanent, however, when a separate slitting
edge to assist in extracting temporary stays such as higher
dose-rate seeds is mounted flush beneath pad 276, as addressed in
the section that follows.
[4747] Use of a tool with pivot is justified when speed and
avoiding frequent withdrawal, exchanging of tools, and reinsertion
are central. The parts immediately associated with stay ejection
below the level of stay refill strip 250 advancement spring 251
mechanical, these must remain in fixed relation throughout the
range of angular adjustment. Therefore, were ejection achieved by
direct mechanical connection as in the fixed embodiment made to the
foregoing description, the incorporation of a joint or pivot,
depending upon the degrees of freedom, would have to allow the
coordinated flexion of all of the parts that must vertically
continue through the joint. Such would cost as much if not more
than several tools made to different angles.
[4748] To allow the distal portion of the tool to pivot without a
loss in stiffness among the parts at reasonable cost, ejection by
means of direct mechanical connection to thumb-ring 244 is
dispensed with, and an electrical fly by wire approach used to
effect ejection regardless of the angle at the joint. While not
specifically shown in the drawings, the structure of a stay
insertion tool with pivot is easily understood in relation to the
mechanical embodiment shown. This involves substituting for
vertically reciprocating thumb plunger-rod 238, one that is
stationary and fastened at its lower end to the ball of a ball
joint. The ball joint thus separates the upper fixed
(nonreciprocating, stationary) portion of the tool from the lower
pivotable or tiltable base seen as 257 in FIG. 91, the parts
thereof rigidly fastened together to move as one.
[4749] In an omnidirectionally privoting tool with ball joint,
joint tightness is set by the tightness of fit of the ball in the
socket as manufactured; alternatively, a small screw in the socket
accessible through a hole in the body of the tool is used to adjust
the joint in tightness as necessary. The joint in the magnetic
probe 241 at the level of the ball joint in rod 238 is woven of
soft iron wire, and must be loose enough to offer little resistance
to ominidirectional movement. The body of the tool mimics the joint
with an upper segment that overlaps the lower where interface at
complementary curved rims. The latter is seldom necessary, a ball
joint with proper internal lining and properly pressed in
manufacture affording smooth action of moderate tightness for
years.
[4750] An electrical wire running alongside or wound around the rod
connects a control button on the outside of the thumb-ring 244 in
FIGS. 87, 88, and 102 to battery 263 and direct current-powered
plunger (reciprocating armature or slug, punching, push-type)
solenoid. The solenoid is fastened to the ball above by connection
to the socket of the ball joint and rivet 258 below. To prevent
abrupt snapping action that would pose the risk of injury to the
ductus and surrounding tissue, the solenoid is viscous, or dashpot,
damped. When energized, the solenoid pulls up rivet 258, causing
ejection tongue 247 to push the next stay in the strip through
ejection slot 248.
[4751] To minimize the need to tilt the upper portion of the tool
as would necessitate enlargement of the entry wound (access
incision), the ball joint and solenoid are placed as far down in
tool base 257 in FIG. 91 as possible. To place the joint as far
down on the tool as possible, stay 231 compartment 250, to include
stay refill strip 250 advancement spring 251 and the stay strip or
clip are generally shorter than in a mechanical embodiment. So that
it will bend in any direction, flexion of magnetic conductor 241 is
achieved by interposition of a segment of soft iron wire woven
cable. The distal tiltable portion of the tool is adjusted in angle
with the aid of a separate probe.
[4752] Power for stay retention, retraction, and recovery
electromagnet 242, a fiberoptic lamp, for example, if clipped to
the tool, and in any embodiment, whether or not incorporating a
base that pivots, a solenoid to eject stays 231, is preferably
obtained from an onboard battery as untethered by a power cord to
afford the operator freedom of movement. So that it will remain
extracorporeal, the battery compartment is positioned high up on
the tool, allowing it to be as large as necessary. Unless the power
is metered or modulated in a manner that makes disconnection from
the control console impracticable, original equipment that uses a
power supply is best powered instead by battery 263, which high up
on the tool, remains extracorporeal.
[4753] Whether incorporating an omnidirectional pivot ball or a
hinge joint, soft iron recovery and retraction electromagnet probe
241 is flexibly jointed by introducing a short segment of soft iron
wire woven to allow bending with no more than moderate force and
minimal loss in magnetic strength across the joint. Thumb
plunger-rod 238 is then jointed by a rounded expansion preceding
its lower margin or lip and complementary receiving expansion at
the top of the lower or distal segment, these serving to impart
omnidirectional flexibility as an integral ball joint. In an
embodiment with only laterally pivoting butt 256, thumb plunger-rod
238 contains a hinge joint below the lower edge of the shortened
tool barrel 239 and just above the level of ejection slot 248.
[4754] The component joints in otherwise rigid vertically disposed
parts to include those internal and the tool body are at the same
vertical level and include stay refill clip compartment 250 at or
slightly above stay 231 seated against the floor of ejection slot
248. Only the hinge joint at the outside of the tool body need be
adjustable in tightness; internal joints in thumb plunger-rod 238
and above ejecton slot 248 can flex freely. To allow the tightness
of the joint at the outside of the body of a tool with lateral
hinge or folding joint pivot to be adjusted, the axle uses a pin
with end caps that screw-on over wave washers.
[4755] Resistance to flexion set by the force with which the
end-caps compress the articulating ends of the upper and lower
segments of the tool body or barrel 239 together, the end-threaded
axle pin with end-caps slotted allows this resistance to be
adjusted with a small screwdriver. Only the outer (external, tool
barrel) hinge joint need be adjustable, those internal
necessitating a hole in barrel 239 to allow access with a
screwdriver. The internal lateral hinge joints of the internal
vertical members usually consist of one sided pressure sensitive
tape. Adjustability in the internal hinge joints is not preferred,
each necessitating a hole through tool barrel 239 just above its
lower margin aligned to it to allow access for adjustment with a
small screwdriver. The tool is not disassembled.
[4756] XVI6. Butt-Pad with Retractable Slitting Edge
[4757] Stays for later recovery contain ferrous metal, either as a
core or as dispersed, to allow magnetic retrieval. While
necessitating reentry at a later date, stays can be extracted with
the same tool that is used to place these with or without stays
loaded. To retrieve the stay or stays necessitates reentry and must
be justified by the severity of the pathology, but allows any kind
of nonabsorbable stay, such as an irradiating seed stay of high
dose-rate, to remain in place over a prescribed period. More
tenaciously ingrown stays, such as irradiating seed stays for
nonpermanent implantation, as addressed above in the section
entitled Arcuate Stent-stays (Stays, Stent-ribs, Ribs) or Stays for
Use with Stent-jackets), may necessitate slight incision before the
tool magnet will be able to extract these.
[4758] A nonabsorbable stay intended for temporary use is not given
a deep outer texture, wetted to encourage tissue ingrowth, or
coated with a strong cement for retention pending extraction. When
the magnetic strength generated by stay retention, retraction, and
recovery electromagnet 242 is insufficient to extract the stay,
rechargeable battery 263 can be removed and the connector to an
external power supply inserted. Extraction can also be expedited
through the use of a retractable cutting edge at the bottom of the
tool to incise the tissue blocking the extraction path. To avoid
the needless tearing of tissue, extraction is along the same path
as was insertion.
[4759] The simplest way to provide a slitting or cutting edge to
assist in clearing the way to a previously implanted stay is to
hone and slightly extend the upper edge of the ejection blade 247
notch or groove at its distal tip seen in FIG. 93. Use of the upper
edge reduces the risk of inadvertent incisions into the adventitia.
The indentation at the distal tip of ejection blade 247 can be a
straight line groove or multisided depression formed to complement,
receive, and stabilize the proximal tip of stay 231. A shallow
ridge or nub along thumb plunger-rod 238 and depression receiving
it serve to signal the operator that the ejection stroke has been
completed and further depressing thumb-ring 244 will cause ejection
blade 247 to continue out ejection slot 248 so that it can be used
incisively.
[4760] Stay extraction can also be accomplished by means of a
separate slitting edge or knife attached flush beneath tool butt
256 or for retraction into a slot midway in a protective pad of
neoprene or similar cushioning material. A blade with slitting edge
and release-retraction button located in a recess at the side of
the tool butt so that a probe must be inserted alongside the tool
to depress the button is not preferred. A small swing-out knife
with semilunar or crescent-shaped cutting edge as in a chavetas
(cigar maker's knife) attached flush beneath butt 256 as shown in
FIG. 91 can be deployed to slash, or predeployed for controlled
incision by rotating the tool.
[4761] The knife is rotated into and out of the deployed or cutting
position by a microminiature rotary solenoid actuated by depressing
an electrical button switch on thumb-ring 244. The solenoid is
mounted within and wired through the vertical space separating
thumb-ring plunger-rod 238 and magnetic conductor probe 241. To
extract a stay, the cutting edge is used to slit the obstructive
overlying tissue, the insertion tool retractive electromagnet is
used to withdraw the stay, and inmate cement line 260 used to seal
the slit. Such a slitting edge mechanism is equally applicable to
any stay insertion tool, including one with an end-pivot, as
addressed in the preceding section
[4762] XVII. Stay Insertion Tool-Inserts and Extension Devices
[4763] The distal girth of the tool sets the practical working
depth for an entry wound of given length. That is, the access
incision is kept smaller the longer the lower narrow portion of the
tool is. To admit the portions up to the upper margin of the
electromagnet triples the length of the incision. Unless the tool
can be used in an open field rather than through an incision,
increasing the distance between cap 243 and finger rings 232 and
249 of a control syringe-configured stay insertion tool such as
shown in FIGS. 87, 88, and 102 only lengthens the extracorporeal
length of the tool and does not contribute to the intracorporeal
reach or working depth, set by the lower ends of stay retention,
retraction, and recovery electomagnet 242 and then air pump 264.
Producing tools in different lengths is preferred to extension
devices in different lengths for insertion between the magnet and
air pump compartments above and the working end below.
[4764] The latter can be made but are needlessly complicated and
expensive. This is because the inmate cement delivery line and any
other lines attached alongside the tool for irrigation, aspiration,
a laser to flow solder on stays, and so on, would have to be
disconnected and reconnected, and to do this would be more
disruptive and potentially aggravating for the entry wound than
simply to withdraw one tool and insert another of different
configuration. Interchangeable distal segments for changing the
stay size or type using the same upper portions of the tool would
not be usable midprocedurally. All such inserts and adapters are
discounted as unusuable midprocedurally as well as offering at best
little economic advantage.
[4765] XVI8. Use of Multiple Component Adhesives with a Stay
Insertion Tool
[4766] This section pertains to the attachment to the stay
insertion tool of a commercial syringe or plural syringes. These
syringes may dispense medication or a sealant cement used as a
hemostat and/or to bond stays ductus-intramurally, for example.
Delivery from auxiliary syringes is distinct from the inmate
cyanoacrylate delivery line described above. However, internal and
attached delivery lines can and usually will be used in
coordination. The primary purpose in a syringe holder attachment
for the insertion tool is to provide a tissue sealant other than
that delivered through the inmate line, which will almost always be
a cyanoacrylate cement. Tissue sealants are provided in syringes
that differ in configuration, and rather than to modify the
syringes or contents, a means is provided for mounting any syringe
to the insertion tool.
[4767] While addressed in terms of supplementary tissue sealants,
the attachment may be used to deliver any kind of medication that
can be delivered by syringe. As commonly seen in epoxy injectors
(applicators, dispensers) several types of surgical adhesives
available for use as hemostat sealants and/or to seal ductus stay
insertion incisions consist of two-components, such as
gelatin-dialdehyde (Geister Gluetiss) or hydrogels, the syringe
applicator being dual-chambered, with one chamber for each
component. Until single component fibrin sealants and other tissue
glues that provide significant bond strength and not just
hemostasis become available, this form of fibrin sealant is likely
to remain preferable.
[4768] For the present application, a one-component adhesive such
as Ethicon OMNEX is preferred; however, two component fibrin
biomatrix sealants supplied in four separate vials, even when
requiring temperature or other different preparation for each of
the four constituents, such as with Baxter Tisseel VH.RTM. S/D (see
Lowe, J., Luber, J., Levitsky, S., Hantak, E., Montgomery, J.,
Schiestl, N., Schofield, N., and Marra, S. 2007. "Evaluation of the
Topical Hemostatic Efficacy and Safety of TISSEEL VH S/D Fibrin
Sealant Compared with Currently Licensed TISSEEL VH in Patients
Undergoing Cardiac Surgery: A Phase 3, Randomized, Double-blind
Clinical Study," Journal of Cardiovascular Surgery (Turin, Italy)
48(3):323-331), can be used by attaching the commercial
dual-chamber syringe to the insertion tool by means of a holder
described below in the sections entitled Powered Stay Insertion
Tool Holder for the Attachment of Medication or Tissue Sealant
Syringes Whether Single, Dual, or Multi-chambered as Supplied for
Tool Slave-follower or Independent Use and Binding of Lines and
Cables Alongside the Stay Insertion Tool.
[4769] To use the inmate cyanoacrylate delivery line to seal the
incisions made by the stay when inserted through the adventitia
(stay insertion incisions) at the same time that an attached
commercial dual-chamber syringe is used as a body entry-incision
hemostat sealant is foreseeable and requires that these be
independently controllable. When the commercial dual-chamber
syringe is used in lieu of the inmate cyanoacrylate delivery line
to seal the stay insertion incisions, its function must be
integrated into the stay insertion function of the tool. When
attached for immediacy as a body entry-incision hemostat, the
commercial dual-chamber syringe must function independently of the
stay insertion function of the tool.
[4770] When the attached syringe is to be freely usable for either
or both purposes, its operation must be instantly switchable from
coordinated to independent use, and such alternate operation is
indeed accounted for in its control as described below in the
section entitled Powered Stay Insertion Tool Holder for the
Attachment of Medication or Tissue Sealant Syringes Whether Single,
Dual, or Multi-chambered as Supplied for Tool Slave-follower or
Independent Use. When unnecessary for either purpose and increasing
the intracorporeally intromitted girth of the tool necessitating
longer incisions to insert its distal working end into the body, a
dual-chamber syringe is not attached.
[4771] Attaching a dual-chamber syringe as a backup hemostat or
safeguard in general is justified when the extension provided by
the maker does not contribute objectionable girth, or when warming
thins out the adhesive long enough for conduction through a
delivery line of smaller diameter and the girth added by combining
this narrower delivery line with a temperature-changing (`cooling`)
catheter is less than that of the usual delivery extension alone.
If inconsistency in heating is not objectionable, an assistant can
use a hot air gun or similar electrical heating device to warm the
attached adhesive delivery line and a cooling catheter dispensed
with. A given stay insertion tool is made for ductus within a small
range of sizes that use the same size stays.
[4772] Extension inserts as addressed in the section above entitled
Stay Insertion Tool Extension Inserts presenting limitations, tools
to insert stays of a given size are generally also made in shorter
and longer tool barrel lengths to facilitate working at superficial
or at various depths within the body. In overall configuration,
however, the tool is standardized, to include a single lumen
adhesive delivery line that ejects the adhesive over the stay
ejection slot at the front of the tool. To allow the use of
adhesives that require the combining of two or more components to
initiate curing (setting, polymerization), the marketed dispenser
or applicator, typically dual chambered, is attached alongside the
tool for actuation by the same thumb-ring.
[4773] However, if to do so interferes with viewability, then the
holder is clamped to a ring stand in a remote location, and the
contents driven through an extension line, actuation necessitating
the addition of an electrical switch to detect depression of the
thumb-ring. The dual component adhesive product is preferably used
with no deviation from the instructions provided by the maker.
Thus, ordinarily, whether the syringe holder is directly attached
alongside the insertion tool or is remote, the extension is
connected to the outlet of the syringe applicator, the components
having already been combined. To retard setting a cooling catheter
with side-holes can be lashed alongside the delivery extension
line.
[4774] The commercial syringe holder and the rest of the mounting
additionally allows for aligning a `cooling` catheter with side
holes aligned to the syringes and/or an end-hole for warming or
chilling the components or the adhesive as mixed prior to, upon, or
following application. Attached outside the tool, the line can be
significantly larger in diameter than could an internal line and
thus deliver an adhesive that is higher in viscosity. Furthermore,
the use of attachments allows reducing the basic tool to models
that differ only in the width of the stays used and in the length
of the tool required to reach down to different working depths.
Using dual-chambered syringes with little if any modification as
purchased, such as to snip off part of a long outlet tube, makes it
possible to significantly reduce the complexity and expense of
manufacture.
[4775] Dual chamber syringe adhesives provided by the maker in
dispensers attached to the tool using the device described in the
section below entitled Powered Stay Insertion Tool Holder for the
Attachment of Medication or Tissue Sealant Syringes Whether Single,
Dual, or Multi-chambered as Supplied for Tool Slave-follower or
Independent Use include Baxter CoSeal.RTM. (Angiodevice
International/Baxter Biosurgery Division, Baxter Healthcare
Corporation, Deerfield, Ill.), which consists of two polyethylene
glycols and dilute solutions of hydrogen chloride and sodium
phosphate with sodium carbonate, and BioGlue.RTM. (CryoLife,
Incorporated, Kennesaw, Ga.), which consists of solutions of
purified bovine serum albumin (BSA) and glutaraldehyde.
[4776] As can other kinds of delivery, irrigation, and aspiration
lines, dual-chambered syringe adhesive dispensers are attached to
the tool with the aid of clips, as described below in the sections
entitled Binding of Lines and Cables Alongside the Stay Insertion
Tool and Use of Stay Insertion Tool Mounting Clips to Fasten an
Adhesive Delivery Line. While the stay insertion tool must be used
in substantially normal relation to the ductus so that extensive
conditions will necessitate numerous incisions, attachments are
devised to least contribute additional tool girth as would
necessitate longer incisions. Suction and temperature-changing
(`cooling` catheter) lines attached alongside the tool affect the
diameter only slightly.
[4777] XVI9. Powered Stay Insertion Tool Holder for the Attachment
of Medication or Tissue Sealant Syringes Whether Single, Dual, or
Multi-Chambered as Supplied, for Tool Slave-Follower or Independent
Use
[4778] XVI9a. Use of Commercial Syringes and Extension Tubes
[4779] For inmate cement delivery line control, both switching
between cement-ahead and cement-follower or cement-during operation
and the timing within this cyclical relation of cement ejection are
controlled mechanically. The first of these is accomplished by the
engagement of thumb plunger-rod 238 to sprocket belt connecting arm
272 by rotation of thumb plunger-rod 238 into the adjacent opening
on one or the other side in the sprocket chain 252 shown in FIGS.
96 and 97, the other through adjustment in the height of slidable
air pressure relief one-way valve shown as 265 in FIG. 95 mounted
in the side of air pump 264. Contained within the tool, no need to
control a remote function is present.
[4780] This differs from the control of the auxiliary syringe
holding frame, which to control at the remote device (with controls
mounted on the holder) would necessitate glancing away from the
treatment site. Observation of the treatment site almost always
accomplished with the aid of an endoscope mounted to the side of
the insertion tool, a need to adjust any controls that had been
mounted to the auxiliary syringe holding frame would necessitate
momentary diverting of the eyes and the removal of one hand from
the tool. [2882] While the tool will almost always be stabilized by
the edges of the small entry wound made to admit it, and the
operator would ordinarily maintain the working end of the tool in
the correct position, the need to glance sideways and remove one
hand can result in jerks and displacement.
[4781] Accordingly, timing control of the auxiliary syringe holder
is accomplished electrically through controls mounted on the tool
itself and not on the auxiliary syringe holder. This operation
consists of adjusting an initial delay and ensuing on-time interval
as described below in the section entitled Control of Auxiliary
Syringe Ejection Time. As addressed below in the section entitled
Binding of Lines and Cables Alongside the Stay Insertion Tool, for
control by touch alone as does not detract from maintaining the
tool in a stable position, attachments to the insertion tool such
as a small liquid nitrogen (LN.sub.2), nitrous oxide, or CO.sub.2
can or a cartridge with spring loaded trigger to release chilled
air into a side- and/or end-hole cooling catheter attached with
clips alongside the tool can be clipped at the side or front of the
gown or attached to a waistband.
[4782] Dependent upon gauge, connection of a cryotherapeutic liquid
nitrogen spray can to the cooling catheter clipped alongside the
insertion tool is by means of conventional intravenous or other
medical tube connectors. The ability to manipulate controls by
touch alone as when attached thus is less likely to affect tool
stability. The chilling effect of devices for attachment to
barrel-assemblies and stay insertion tools can be moderated in
temperature and reduced in exit rate by means of numerous existing
kinds of cryosurgical and cryotherapeutic apparatus, to include the
use of a thermal barrier (see, for example, Holland, T. D., Joye,
J., Williams, R., and Williams, R. 2004. "Safety Cryotherapy
Catheter," U.S. Pat. No. 6,811,550.
[4783] When the operator has determined that the stays can each be
inserted with an action that is consistent in time from one to the
next, the dual interval (interval off or delay followed by an
interval on) timer is adjusted to effect a change from
cement-before to cement-during operation. However, unless
medication of inordinate cost is being delivered, the consequence
of unanticipatable hesitation or discovery amounts to no more than
an inappropriately timed release. If necessary, the substance
released, whether medication, tissue adhesive, or both is swabbed
away. If consistency appears improbable, a tool that incorporates
break contacts at the top and bottom of the thumb rod stroke is
used to establish the start of cycle times for release before or
release after the downstroke operation, thus reducing the incidence
of inappropriate discharge.
[4784] The substitution of electrical for mechanical control over
the inmate cement delivery line to switch from cement-ahead to
cement-during operation would allow dispensing with the twist-right
twist-left sprocket and air pump sliding pressure relief aperture
elements but necessitate incorporating a dual adjustable interval
relay module into the tool. Furthermore, the sprocket mechanism
cannot be misadjusted to misassign action to release-ahead to
release-after action. Furthermore, at least as of the time of
filing, the state of the art relay module measures 2 inches on a
side with corners projecting on both sides of the tool, which
circumstance was felt best avoided. Two or more component adhesives
are not applied with one component delivered through the inmate
line and the other component delivered through a line or lines
attached to the side or front of the tool.
[4785] Similarly, to coordinate the application of adhesives so
that the single lumen line built into the stay insertion tool is
used to apply a coating of cyanoacrylate cement to the trailing end
of the upper surface of each stay for sealing the ductus entry
incision, while a commercial tissue sealant, typically dispensed
from a dual-chambered syringe, is used to apply a two-component
adhesive-hardener to the front and middle portions of the upper
surface of each stay is considered to be justified only with the
advent of cements that from the standpoint of promoting the
recovery of integrity within the ductus wall are superior to any
currently available.
[4786] If the extension provided by the maker is rigid and not
conformant to the tool, it is replaced with flexible tubing.
Two-component tissue sealants that demand pressing together of the
surfaces to be bonded for two minutes or longer are too slow to
serve as stay insertion incision adhesives, much less
ductus-intraparietal stay and laminar bonding agents. The
preferability of cyanoacrylate cement to these is clear. The
attached line for delivering tissue sealant can be used
independently of the stay insertion function for use as a hemostat
or in direct support in and timed to stay insertion. Whereas the
inmate line for the delivery of a bonding agent or tissue sealant,
usually cyanoacrylate cement, cannot be used independently of stay
insertion, a separate syringe of cyanoacrylate can be added using
the commercial tissue sealant holder described below.
[4787] Numerous modifications of the holder to be described are
considered obvious. Increasing the width of the holder and using a
more powerful motor or separate motors and leadscrews to either
side of the syringes, or using an increased gear reduction ratio
with one or two motors makes it possible to load a syringe or
combination of syringes that require greater force to depress the
plunger or plungers. Such can be used to control multiple single or
dual-chambered syringes in adjacent relation in one holder where
the delivery line is shared, each syringe supplying a different
substance to the treatment site. A dual-chambered syringe can be
used to mix and dispense components of one end-substance, such as a
two-component tissue cement, or to provide different substances
whether these consist of medication or tissue sealants, provided
these can be passed down a common delivery line.
[4788] Very thick (viscous, viscid, heavy) fluent substances may be
unsuited to integration into the stay insertion sequence and while
dispensable using an auxiliary syringe equipped with motors of
adequate power, may have to be separately controlled. The
additional force essential to expel less viscous substances from
the syringe may necessitate separate motors and lead screws to
either side of the syringe. The use of multiple syringes with any
one insertion tool must therefore consider the efficacy of the
contents of each syringe when mixed and fed through a common
delivery line. Compatible contents can be merged from a separate
input line from each syringe or dual-chambered syringe. Unless
operator errors would be inconsequential, a second plural auxiliary
syringe holder for use independently of the other is inserted into
a second socket mounted to the opposite side of the tool inmate
cement chamber (cement air pump and cartridge housing).
[4789] The use to one side of more than one auxiliary syringe
holder when one of these can be attached at the opposite side is
discouraged as conducive to operator error and depending upon the
additional weight to the one side, manual fatigue. Procedures
should seldom last long enough that the weight of even two
relatively powerful small gearbox motors on the holder to one side
without a counterbalancing weight on the other side should result
in manual fatigue. Switchable operation from stay insertion tool
slave-follower or tool stay ejection synchronous to independent
mode is unaffected by the number or kind of syringes loaded.
Holders can be attached to either side of the tool to provide right
and left-handed models with the thumb-ring switches for the holders
either attached to the thumb-ring for slidable rotation to the
opposite side, as preferred, or the switches duplicated at either
side of the thumb-ring.
[4790] The conductors for the thumb-ring switches must have
sufficient slack to allow the thumb-ring to be rotated. For
medication or cement to be introduced intraincisionally, that is,
carried forward on the surface of the stay into the incision as the
stay enters into the wall of the ductus, the terminus of any
auxiliary syringe delivery line must be positioned directly above
the stay ejection slot, which must therefore be interchangeable in
position with that of the inmate cement delivery line. Additional
auxiliary syringes attached by means of a holding frame must
terminate at points adjacent or nearby that over the ejection slot.
With this understanding, holders can be attached to both sides of
the tool inmate cement housing, with one or both of these sides
used in slave-follower or independent mode.
[4791] Placement of the outlet ends or the termination of auxiliary
syringe delivery lines at the sides of the tool foot allow the
application of medication, such as anti-inflammatory,
anti-infective, or analgesic, just before or after stay insertion.
The simultaneous use and evacuation into a common delivery line of
plural syringes assumes that the contents of each syringe is
compatible with that of the other syringes as not to require
segregation in separate delivery lines or in separate lumens of
multilumen tubing, and that no degradation in the efficacy of any
ingredient will result from the fact that the entire delivery line
from syringe to the distal line terminus is charged with this
mixture.
[4792] As medication applied to a. Both the upper and lower
surfaces of the stay in cement-ahead operation and b. An adjustable
extent of the upper surface in cement-during operation is largely
removed by squeegeeing, that is, swept away by brushing against the
sides of the incision as the stay penetrates into the ductus wall,
the addition to the medication of a thick and adherent substance
will sometimes assist in introducing more of the medication into
the wall of the ductus. Provided withdrawal is unobjectionable or
avoidable through the use of a probe, delivery line termini can be
bound for interchangeable positioning directly above the stay
ejection slot by means of a small tissue compatible elastic
band.
[4793] In a tool wherein the retention and recovery electromagnet
reciprocates down and up along with the thumb-ring, this will add
some resistance to movement and likely require occasional
withdrawal in order to adjust the elastic band. Even though it
would allow more flexibility in the use of auxiliary syringes
without the need for withdrawal, the incorporation of a turret
mechanism for rotating different syringe and delivery lines or for
aligning separate syringe outputs to different tube extensions for
rotation into position above the stay ejection slot is discouraged
as distracting and conducive to human error as well as introducing
a unjustified complexity and expense.
[4794] Auxiliary syringe holders on opposite sides of the tool can
share a dual interval relay as well as the break contact terminals
as addressed below in the section entitled Control of Auxiliary
Syringes when inset into only one side of the cement air pump and
cartridge housing. However, this will cause the holder motors to
either side to conform to the same cycle even though the deposition
to one side of an anti-infective, for example, must be deposited
just before the deposition of a sealant, for example. By contrast,
incorporating a timing relay into each holding frame as an integral
component allows each auxiliary syringe to be synchronized to the
tool stay ejection cycle with different timing, for which the
increased cost is considered justified on the basis of uniformity
and the independent usability of the holders, as well as the
additional flexibility imparted.
[4795] If the action overall is slightly acyclical or aperiodic so
that the relation between the subcycles to either side
progressively changes or desynchronizes, the control on one of the
dual interval timing modules must be adjusted midprocedurally.
Furthermore, to duplicate the contacts on both sides is no more
costly than to provide incorporate conductors for a holder on the
opposite side. For clear distinction in use, tissue sealant can be
segregated in the holder attached to one side of the tool, while
medication is provided by the holder attached to the other side.
Either or both holders can be set for slave-follower or stay
ejection cycle independent, that is, operator discretionary direct,
control.
[4796] The specific types of substances and timing control between
the sides that are possible represent a large number of
combinations and permutations. Provided an unused delivery line is
clipped in position for nonintaincisional application, the proximal
end of the delivery line previously in use can be disconnected at
the bottom of the socket and the unused line connected. Usually the
connection point will be far enough above the entry wound to allow
this without the need to withdraw the tool. In this way, an
assistant can connect or replace syringes containing certain
substances with others as the procedure progresses. Otherwise,
changing delivery lines requires withdrawal of the tool and
replacement of the line or lines.
[4797] Rather than to manipulate different delivery lines providing
substances intended for intraincisional application midprocedurally
(ordinarily the inmate cement and an auxiliary syringe line), it
will usually be preferrable to withdraw one tool and exchange it
for another that has been configured for continuation of the
procedure as desired. With an assistant to configure the tool as
necessary, rotating two tools will allow any response within the
operational limits of such tools. One object of the invention being
to accomplish an improved form of stenting with the least trauma,
stay insertion tools are long and narrow to allow deep access
through small incisions.
[4798] Hence, auxilliary delivery lines and clips as described
below in the section entitled Stay Insertion Tool Mounting Spring
Clips for attaching these are mounted to sides of the tool only as
required for the specific procedure. Whether operated as a. A
passive (slave, follower, dependent, tool cycle synchronized)
function tied to tool function for providing a discharge of a
tissue sealant coordinated with stay insertion for sealing stay
insertion incisions, b. Independently (tool cycle nonsynchronized)
to stay insertion as a hemostat sealant, anti-infective,
anti-inflammatory, or other medication, or c. As switchable between
either kind of operation, a two-component or dual-chambered syringe
must be mounted off to a side, or it will interfere with direct
viewability of the site to be treated.
[4799] An attached endoscope can be used to view the toe of the
tool foot but not portions of the tool at higher levels. As
described below in the section entitled Powered Stay Insertion Tool
Holder for the Attachment of Medication or Tissue Sealant Syringes
Whether Single, Dual, or Multi-chambered as Supplied for Tool
Slave-follower or Independent Use, since dual-chambered syringe
applicators or dispensers provided with dual-component adhesives,
for example, may interfere with viewability of the treatment site
when attached to the insertion tool in adjacent relation, these are
raised and set off to a side of the tool at an angle. Making the
dual syringe holder of transparent material having optical clarity
can contribute some viewability, but since the holder can be
rotated, transparency is unnecessary. The amount of adhesive
remaining is easily seen.
[4800] XVI9b. Avoidance of Remote Syringe Placement and Long
Adhesive Delivery Lines
[4801] To keep the components of a two-component tissue cement
separated would necessitate modification of the double chamber
syringe, the attachment to each chamber of an extension line, and
filling each line with a component. Insufficient cement likely to
fill longer extension lines and much cement likely to remain
following the procedure, avoiding waste would necessitate attaching
the extension lines and then introducing an inert filler material
at the top of the chambers to drive the components down line to a
distal segment of column length somewhat longer than that to be
used. Compared to cyanoacrylate cements, two-component adhesives
are slow to achieve initial set.
[4802] Thus, under normal circumstances, even when the parts have
already been mixed, the additional transit time to move over the
increased distance from the syringe outlet to the treatment site is
noncritical in that it does not significantly reduce the open time
available to promote clogging of the delivery line. Rather than to
enhance flowability, the use of a `cooling` catheter to warm the
line will more likely accelerate setting (polymerization), which
is, however, useful to accelerate curing once the sealant has been
applied. Whether chilling the line to retard polymerization will
allow the use of a narrower line depends upon the concurrent effect
on viscosity, which is likely to be the increase thereof.
[4803] Ordinarily, an auxiliary holder syringe-contributed
two-component sealant is used as a hemostat under independent or
tool stay insertion cycle nonsynchronous operation and as a stay
insertion incision sealer and ductus intraparietal stay binder when
switched to synchronous operation. Thus, the time following mixing
of the components and initiation of polymerization that the cement
is left to linger before use is shorter with the mix kept moving.
However, if used only to seal stay insertion incisions, the rate of
consumption, even without an added length of tubing, invites
incrassating or congealing, the slower delivery prompting clogging.
The quantity of adhesive to fill long lines is wasteful.
[4804] For these reasons, a position for a dual-chamber syringe
that is more remote from the insertion tool, such as one pumped
from an adjacent stand through a relatively long extension line
rather than attached to the tool and offset at an angle as will be
described is discounted. This mounting satisfies the requirement to
position the holder proximate to, without visually obstructing, the
point of application and surrounding treatment site. To avoid the
cost and complexity of actually integrating the delivery of two or
more component adhesives into the mechanism of the insertion tool
as has been done to include a single-component adhesive-hardener
delivery line, marketed applicators are made usable without the
need to modify or repackage these beyond snipping off a portion of
an extension tip or "applicator" when too long.
[4805] Attachment to a stay insertion tool of a commercial surgical
adhesive dispensing device such as a dual-chambered syringe will be
described in relation to the control, or thumb and finger ring-type
syringes shown in FIGS. 87 and 88, the auxiliary syringe attachment
shown in FIGS. 101 thru 103. Two-component adhesives such as
CoSeal.RTM. (Angiodevice International/Baxter Biosurgery) and
BioGlue.RTM. (CryoLife), are sold with dispensers or applicators
that have been configured for the specific ingredients that each
uses. The dispensers are therefore different in dimensions,
conformation, amount of adhesive expelled per unit distance of
plunger depression, and so on.
[4806] Nevertheless, a single holder must allow any given syringe
to be attached to the stay insertion tool. The use with minimal if
any modification to off the shelf adhesives and applicators
eliminates complexity, as does controlling the attached syringe
electrically rather than through a complicated mechanical linkage.
As addressed above in the sections entitled Multiple Component
Adhesives and Use of Commercial Syringes and Extension Tubes,
auxiliary syringes, typically dual-chambered, or conventional
syringes containing medication or a commercial tissue sealant, are
attached to a stay insertion tool by means of a holding frame, or
holder.
[4807] XVI9c. Stay Insertion Tool Auxiliary Syringes
[4808] XVI9c(1). Control of Auxiliary Syringes
[4809] Unlike the cement delivery line built into the tool,
commercial syringes for attachment to a stay insertion tool must be
positioned off to a side of the tool. This in itself makes the
control of the syringe by mechanical means complicated. Since
commercial syringes are self-contained devices that do not conform
to prescribed dimensions, any one holding frame must accept
syringes over a range of shapes and sizes. Commercial syringe
chambers and tips differ in internal diameter and the contents in
viscosity, so that the amount of adhesive expelled for a given
downward movement of the plunger or plungers is different for
each.
[4810] An auxiliary syringe holder is a battery powered syringe
driver or syringe pump for attachment to a stay insertion tool. It
can be used to dispense a two or more part adhesive, therapeutic
solution, fluid medication, or component syringes can be divided to
deliver cement and a medicinal substance simultaneously in the
relative proportion desired. At the same time, the stroke of the
stay insertion tool plunger-rod 238 and the timing of its detrusion
(depression) is dictated by its stay feeding and ejection function,
which is tied to the length of the stays the tool is meant to
insert, and to this extent is the same regardless of the overall
length of the tool.
[4811] Nevertheless, differences in stroke and the variability
required in the timing and quantity of syringe expulsion relative
to tool plunger-rod 238 depression with various commercial syringe
plungers militates against a mechanical linkage of the syringe to
the tool; no simple, unobtrusive, dependable, and easily maintained
mechanical linkage or cabling would allow even one auxiliary
commercial syringe to be connected and controlled with the
variability in timing and the amount of discharge required when the
tool plunger-rod 238 is depressed. By contrast, to coordinate the
action of a commercial dual-chambered syringe to that of the
insertion tool by electrical means is relatively straightforward
and inexpensive.
[4812] In place of the intricacies of applying adjustments with a
mechanical system, timing relations are applied empirically by
adjustment to the dual interval timing relay or relays during
testing before use. Such timing control makes it possible to
initiate the onset of adhesive outflow onto the surface of the
ductus just prior to the ejection of a deep surface-textured stay
which then carries the adhesive forward into the ductus wall on
both its upper and lower surfaces, or cement-ahead operation. If
initiated during stay ejection, then the onset and duration of
adhesive outflow is timed to vary the extent of the upper surface
of the stay that is coated, which is referred to as cement-follower
operation.
[4813] Emptying of the syringe or syringes in a given holder must
be variably synchronizable to the stay ejection cycle, as well as
switchable to independent operation whenever the operator wishes to
apply medication or sealant in a discretionary manner. In some
instances, as when the deposition of a local anesthetic or
anti-infective must precede the deposition of a sealant, collateral
synchronization as to sequence and the amount of substance expelled
between the syringes attached to either side of the tool will
matter. While the operator may choose to use auxiliary syringes in
an exclusively discretionary manner for an entire procedure, for
greater applicability and to cover numerous contingencies, the
apparatus must be capable of switching from independent function to
the variable and differential synchronizing to the stay insertion
cycle of two attached holders.
[4814] For a syringe chamber, outlet, and extension or delivery
line of given internal diameter used to dispense a fluid of given
viscosity, the amount of the fluid expelled (discharged) is
determined by the distance of syringe plunger downward travel or
excursion (distance depressed). This is determined by the speed of
the frame motor, the time that the motor is on, and the pitch of
the lead screw thread. Of these, only the interval over which the
frame motor is on is normally varied, this by adjusting the
settings on the dual-interval relay. Otherwise, the operator can
switch to direct control independent of the stay ejection cycle at
which time the motor will draw current directly from the battery,
the relay then shunted (bypassed).
[4815] Substances not sold in syringes afford some choice of
syringe and extension or delivery line, but once the syringes and
delivery lines to be used have been chosen, to mix the contents of
syringes attached to either side of the tool in a certain
proportion will require adjusting the side-to-side related onsets,
durations, and terminations that each holding frame motor is on.
More reliably as well as more flexibly, the holder is driven by a
lead screw which is rotated by a miniature direct current spur gear
head motor of the type manufactured, for example, by Lynxmotion,
Inc., Pekin, Ill. The motor is actuated upon separation of the
break contact terminals mounted at the junction between the
stationary cement and the reciprocating battery-electromagnet
housings.
[4816] The motor or motors are used at constant speed, control over
the quantity of material discharged by the syringe or syringes
being determined by the interval over which the plunger is
depressed. Using motor speed to compensate for variation in the
speed with which the operator depresses the thumb-ring is
considered an unnecessary complication and expense. The occasional
misdeposition of medication or cement due to hesitation or
distraction may require swabbing or the use of an attached suction
line (aspirator) but poses no risk. For general hemostatic use, a
simple momentary contact push button switch is used. Switching from
direct operator (independent, discretionary) to slave control
introduces break contacts and a double interval timing module into
the circuit such that separating the contacts by depressing the
tool thumb-ring sends current to the timing module which controls
the motor on the holding frame.
[4817] In this way, the timing module is used to coordinate the
ejection of adhesive or tissue sealant by the auxiliary syringe or
syringes in the holder to the mechanical stay insertion tool
ejection cycle. Otherwise, recovering excess adhesive by means of
an attached aspirator line dispenses with the need to insert a swab
through the small entry wound. To coordinate the release of
adhesive to stay ejection, the break contact terminals on the tool
and an interval timing module are used to eject a settable amount
of adhesive only when the thumb-ring and central spring shaft of
the insertion tool move either up or down. The amount of adhesive
and segment of the tool operational cycle over which the ejection
of the adhesive occurs is variable according to the interval
settings applied to the module.
[4818] XVI9c(2). Tissue Sealant Syringe Holder (Holding Frame) and
Attachment
[4819] When attached to the stay insertion tool, a commercial
tissue sealant syringe must be usable both for hemostasis
independently of the stay insertion function of the tool, as well
as in direct and closely coordinated support of stay insertion.
Control over the small electrical motor used to depress the syringe
plunger must therefore be switchable between independent and
tool-driven (locked, tied, follower) use. The viscosity at the end
opening (nozzle, spout, outlet, ejection tip) will usually allow
use in the small amounts required for coordination with stay
ejection; if not, an end-opening adapter to reduce the diameter
(reducer) is used.
[4820] Excessive internal cohesion or surface tension
(Plateau-Rayleigh instability) that results in the formation at the
end-opening of adherent beads (globules, drops) of sealant which
interfere with the smooth flow essential for fine use may
necessitate the addition of a diluent to either or both components
or the need to periodically withdraw and dip if not agitate the end
of the tool in a diluent or solvent. Differing in configuration and
dimensions, some syringes or combinations of syringes may require a
special holding frame. Making the distance between upper and lower
compressive plates in the frame large enough to accommodate most
commercial syringe products and using the onboard motor to bring
the plates used together to clamp the specific syringe between the
two plates will, however, accommodate almost every commonly sold
syringe, the majority about 31/2 inches long with "needle" or "tip"
removed or trimmed.
[4821] Commercial syringes may be dual-chambered to separate two
components that when mixed together initiate curing within the
syringe before reaching the end opening Extensions are usually
available from the syringe producer, and the syringes contain a
sufficient amount of each component to fill the extension and last
the procedure. The extension provided by the maker can usually be
used as the fluid channel that passes through the outer bendable
metal jacket of the support arm and connecting cable described
below. If this is too short, ordinary catheter tubing can be
used.
[4822] Although the components are mixed initiating curing
(polymerization) within the syringe mixing chamber or mixing
nozzle, the setting time of commonly available such products is not
so fast as to require that the length of the extension needed to
mount the syringe to the stay insertion tool be kept to a minimum.
The delivery line can thus be allowed sufficient length to position
the holding frame unobtrusively off to a side. While the syringe is
always mounted prior to the procedure, the setting time will
determine whether the extension tube is filled with the mixed
components before the procedure is underway or the need therefor
arises.
[4823] Although the sealant is not likely to reach initial set, in
order to not detain the procedure, the small motor used to drive
the plunger must be capable of short-term continuous-duty torque
output sufficient to fill the line quickly. To allow the use of
either the inmate or attached sealant for ductus-intramural stay
bonding, an elastomeric ring is used as the most distad attachment
of the two lines at the front of the tool, and a probe is used to
shift the tip of either line into position directly above the stay
ejection slot. When the attached syringe is used as a hemostat, the
tip of the inmate cement line is left in position above the
ejection slot.
[4824] XVI9c(3). Structure of Tissue Sealant Syringe Holder
[4825] XVI9c(4). Stay Insertion Tool Auxiliary Syringe Holding
Frame Attachment
[4826] Since only the syringe and enough of its outlet `needle` or
`tip` to engage the socket described below are used, a holding
frame or holder of reasonably standardized size can be provided
that will allow adjustment to accommodate almost any one single or
dual chambered syringe. BioGlue.RTM., Tisseel.RTM., and
CoSeal.RTM., for example, are dispensed from dual-chambered
syringes that mix the components internally, whereas Gluetiss.RTM.
is dispensed from two separate syringes, one larger for the
gelatin-resorcinol solution component, the other smaller for the
aqueous glutardialdehyde and glyoxal hardening solution
component.
[4827] Holders configured for these and future tissue sealant
syringes are made out of any suitable plastic by molding, or
fabricated out of half-inch wide plastic or nonferrous metal flat
strip stock, for example. Gluetiss.RTM. is mixed on the treatment
tissue, with a 20:1 to 10:1 ratio of glue to hardener. While the
syringe that contains the hardener is smaller in diameter and
length, it is not designed to deliver its component in the
appropriate proportion when the plungers are depressed alongside
one another to the same depth as would allow the holder mechanism
to be made in a relatively simple form as preferred.
[4828] More specifically, the correspondingly disproportionate
rates of depression between the two syringe plungers required to
expel the components in the correct proportion would necessitate
adding a reduction gearbox in addition to a mixing nozzle.
Excessive open time precluding the immediate sealing of incisions,
surgical adhesives other than cyanoacrylate cement may require the
addition of an accelerator to reduce the interval prior to initial
set. With the appearance of dual syringe tissue sealants that set
more quickly and release the contents of the syringes in the
prescribed proportion for a given downstroke of the syringe pistons
(piston plungers, plungers), the holder is made as is one for a
single (usually dual-chambered) syringe.
[4829] Turning now to FIGS. 101 thru 103, this is in the form of a
miniature press or vertically disposed vise having an upper plate
or `jaw` that drives the syringe piston plungers down by means of a
lead screw, so that even when not united as shown in FIGS. 101 thru
103, the syringe pistons are driven down together. The shaft of
motor 286 is connected to gear reduction box 288 by means of an
unseen full coupling union consisting of an ordinary starter
joint-shaped joint-encircling metal sheath having a keyed internal
cross section complementary to that of the motor shaft. Gear
reduction box 288 is in turn connected to lead screw 278 by full
coupling union 287.
[4830] Auxiliary syringe holding frame 284 accommodates
dual-chambered commercial syringes such as that sold under the
BioGlue.RTM. label, with internal mixing nozzle 292 and single or
unified bottom-opening exit-hole 279. Auxiliary syringe holding
frame 284 incorporates no onboard controls, allowing its reversal
for connection to the line entry socket on the opposite side of the
tool without impeding use by a nonambidextrous operator or
assistant. Dual chambered commercial syringes 280 and 281 are made
to mix the components of the tissue sealant in the correct
proportion automatically when the single thumb rest depresses both
plungers.
[4831] The upper halves of holding frame 284 sides 282 and 283 are
slotted down the center from near to the top to half way down to
serve as guideways to complementary projections at the sides of
screw 278 follower crosspiece 285. To allow the syringe to be
replaced midprocedurally, side pieces 282 and 283 of auxiliary
syringe holding frame 284 are not folded inward. Small extensions
from follower strip or lead screw 278 follower crosspiece 285
insert through the slots cut down the center of each side of
auxiliary syringe holding frame 284. Follower crosspiece 285 thus
rides up and down the side slots as guideways when small direct
current gear head motor 286 rotates lead screw 278 driving lead
screw follower block 285, which is resistance welded to the bottom
of carriage plunger depressing follower crosspiece 285.
[4832] As shown in FIG. 101, lead screw 278 extends down through
upper frame crosspiece 285 and press-down crosspiece strip with
integral lead screw follower block 289 with integral lead screw
follower block having end projections that fit into and ride down
the slot guideways in sides 282 and 283. Upper frame crosspiece 285
spans across the top of auxiliary syringe holding frame 284 from
side 282 to side 283, is folded over, and resistance welded to
sides 282 and 283 of frame 284. The thread of lead screw or bolt
278 extends down enough to allow the syringe to be fully
emptied.
[4833] Bottom crosspiece 291 has a hole at the center to admit dual
syringe mixing nozzle 292 and thus support dual syringe including
barrels 280 and 281 from beneath when dual syringe thumb rest 294
is forced downward by press-down crosspiece strip with integral
lead screw follower block 289. Auxiliary syringe holding frame 284
lower crosspiece 291 supports and passes through the bottom dual
syringe unified outlet 279 in which the components from either
barrel are mixed, some portion of the exit nozzle 292 distal
thereto retained for insertion and friction fit into the upper end
of cable connecting delivery extension line or auxiliary syringe
holding frame 284 supporting arm and connecting cable 290.
[4834] A mixing nozzle such as seen in the CryoLife BioGlue.RTM.
syringe has the spreading tip removed but is otherwise left intact.
Since during a procedure, press-down crosspiece strip with integral
lead screw follower block 289 is moved upwards only to replace a
spent with a full syringe, the syringe is secured in position. Just
as the frame bottom crosspiece 291, the ends of frame top
crosspiece 285 are folded down over as to be vertically flush, and
resistance welded to the upper ends toward the tops of frame sides
282 and 283. To insert a new syringe into the holder, motor 286 is
used to drive press-down crosspiece strip with integral lead screw
follower block 289 upward enough to allow the spent syringe to be
removed and the new syringe inserted.
[4835] Dual syringe mixing nozzle 292 through the center hole,
motor 286 is reversed to clamp the syringe between bottom
crosspiece 291 and press-down crosspiece strip with integral lead
screw follower block 289. Further depression of press-down
crosspiece strip with integral lead screw follower block 289 and
dual syringe thumb-rest 294 causes dual syringe barrels 280 and 281
to expel their contents. The parts must be sufficiently robust that
off-axis lead screw or bolt 278, hence eccentric (moment arm, lever
arm) application of compressive force, will not achieve a magnitude
sufficient to jam the end protrusions of press-down crosspiece
strip with integral lead screw follower block 289 in its side
guideways.
[4836] XVI9c(5). Connection of the Holding Frame to the Stay
Insertion Tool
[4837] As shown in FIG. 102, attachment of auxiliary syringe
holding frame 284 to the stay insertion tool is by means of
auxiliary syringe holding frame supporting arm and connecting cable
290 shown in FIG. 105 with upper end engagied by dual syringe exit
mixing nozzle 292 and lower end engaged in stay insertion tool
auxiliary syringe holding frame supporting arm and connecting cable
socket 296 shown in FIG. 106. Auxiliary syringe holding frame
supporting arm and connecting cable socket 296 is mounted within
auxiliary syringe socket block 297 to the side of vertically
stationary cement air pump and refill cartridge housing 264, with
delivery of the mixed cement, drug, or other therapeutic substance
passing down to the work site through polymer auxiliary syringe
delivery line 298.
[4838] As shown in FIG. 105, auxiliary syringe holding frame
supporting arm and connecting cable 290 consists of outer bendable
preferably hexagonal structural casing or sheath 299, containing
polymer syringe extension tube or cement and therapeutic substance
delivery channel 300 and electrical conductors 301 thru 306 leading
and from auxiliary syringe holding frame motor 286 and dual
interval timing relay 293 to stay insertion tool inmate battery
263. Auxiliary syringe holding frame supporting arm and connecting
cable socket 296 includes electrical contacts at its bottom for
connection to electrical conductors 301 thru 306. 102.
[4839] FIG. 106 shows the position of auxiliary syringe holding
frame supporting arm and connecting cable 290 socket 296 when
attached to the right hand side as shown in FIG. Dual interval
timing relay 293 substantially eliminates the need for a
microcontroller onboard the auxiliary syringe holding frame to
coordinate the timing of stay insertion and auxiliary syringe
discharge when not separately controlled by the operator. If
auxiliary syringe ejection is synchronized with or at an interval
in relation to inmate tissue cement pump 264 so that delivery line
298 shown in FIG. 102 should discharge as close to ejection slot
forward extension 269 of inmate tissue cement pump at the front of
the tool as shown as 264 in FIG. 102, then line 298 is rotated from
its ordinary position in separate or unsynchronized use whereby it
courses down the side of the tool.
[4840] The clips or nonallergenic elastic bands used to secure
delivery line 298 to the side of the tool make moving the delivery
line 298 ejection opening around into adjacent relation to ejection
slot forward extension 269 quick and simple. Small ring rubber
bands allow the two delivery lines from two auxiliary syringes to
be quickly rotated aronud the tool to any position desied, allow
either line to be crossed over the other, and since the delivey
lines can branch, the area coated can be inceased with the banches
rotated to any peripheral position surrounding the tool.
[4841] In a stay insertion tool with a second socket for attachment
of an auxiliary syringe holding frame on the left hand side, a
second auxiliary syringe holding frame supporting arm and
connecting cable socket 296 is mounted on the opposite side of
inmate tissue cement air pump 264 as shown in FIG. 106. In FIG.
106, the structures surrounding thumb plunger-rod 238 and auxiliary
syringe delivery line 298 such as the tool barrel 239 seen in FIG.
102 have been omitted for simplicity. Auxiliary syringe holding
frame supporting arm and connecting cable 290 thus serves both for
structural support and electrical connection to the insertion tool
auxiliary syringe holding frame 284 components, with electrical
current drawn from battery 263 in the upper compartment of battery
and stay retention, retraction, and recovery electromagnet 242
compartment.
[4842] As a distinct component, auxiliary syringe holding frame
supporting arm and connecting cable 290 is thus a miniature
combined fluid and electrical conduit. As a structural element,
casing or sheath 299 of auxiliary syringe holding frame supporting
arm and connecting cable 290 is preferably made of nonferrous metal
such as aluminum with sufficient flexibility for its wall
thickness, diameter, and as shown in FIG. 104, typically of
hexagonal cross-section allows the operator to bend it if necessary
in order to obtain both manual clearance and a better view of the
working field and syringe or syringes during operation.
[4843] XVI9c(6). Supporting Arm and Connecting Cable
[4844] FIG. 102 shows an auxiliary syringe holding frame containing
a double syringe 284 with supporting arm and connecting cable 290
positioned for use, while FIG. 104 shows a supporting arm and
connecting cable 290 before having been bent by the operator to
gain the best line of sight and clearance to the working site.
Auxiliary syringe holding frame supporting arm and connecting cable
290 is radially and bilaterally symmetrical. Further to obtain a
clear view, a cabled lamp, endoscope, or angioscope, not shown in
the drawing figures, is clipped or lashed alongside the tool.
[4845] Since the viewing angle may change during the procedure,
auxiliary syringe holding frame with double syringe 284, supporting
arm and connecting cable 290, and conductors 301 thru 306 are
sufficiently pliable to allow frequent bending without fatigue
fracture. In FIGS. 104 and 105, auxiliary syringe supporting arm
and connecting cable 290 conductors 301 thru 306 have end contact
pins secured in position at either end by protrusion through holes
in end caps 307 and 308, through which conductors 301 thru 306
protrude with intervening electrical insulation.
[4846] FIG. 105 shows an auxiliary syringe supporting arm and
connecting cable 290 in cross section or with either end-cap
removed. At either end, auxiliary syringe holding frame supporting
arm and connecting cable 290 thus resembles the base of a vacuum
tube, but with a central opening for polymer syringe extension tube
or cement and therapeutic substance delivery channel 300. This
configuration allows end caps 307 and 308 to key the engagement of
auxiliary syringe holding frame supporting arm and connecting cable
290 in auxiliary syringe holding frame supporting arm and
connecting cable socket 296 and stay insertion tool inlet socket
296 mounted to the side of inmate cement pump 264 compartment.
[4847] The fluid delivery line within is made either from an
extension provided by the syringe maker or a length of catheter
polymer tubing. End-caps 307 and 308, which must securely position
and insulate the fluid and electrical conductors inside it can be
made of any strong plastic or mica, for example, these parts bonded
together by means of a commercial adhesive selected for the
specific materials used. The engagement of auxiliary syringe
supporting arm and connecting cable 290 end-caps 307 and 308 in the
upper and lower sockets can be viewed as tenons keyed by the
protruding pin contacts, with the fluid channel at the center
inserted into sockets considered complementary mortises somewhat
similar to the connection of the stem to the shank of a smoking
pipe.
[4848] To rigidly support auxiliary syringe holding frame 284, the
upper or holder end of auxiliary syringe holding frame 284
supporting arm and connecting cable 290 must be firmly bonded by
means of a strong adhesive to frame 284 about the syringe outlet
which protrudes through holding frame bottom crosspiece 291, and
which socket block 297 surrounds. To avoid the need for socket
blocks with a different internal conformation at the upper or inlet
end for each different kind of syringe, the inlet is funnel-shaped.
Conductors 301 thru 306 to double or dual interval relay module
293, thence to motor 286 are bonded along the inside of frame 284
by intermittent application of a hot melt adhesive or small top or
side acceptance spring arm clamps bonded to frame 284 with
cyanoacrylate or hot melt adhesive depending upon the specific
materials used.
[4849] In FIGS. 101a and 103, 294 is the dual syringe thumb-rest
and 295 the finger stops. In the embodiment depicted in FIGS. 101
thru 105, battery and stay retention, retraction, and recovery
electromagnet 242 compartment moves down and up with thumb-ring
244. In this embodiment, auxiliary syringe holding frame 284
supporting arm and connecting cable 290 is attached by insertion of
its tool end into a socket that is bonded to the outside of
stationary cement cartridge and air pump 264 compartment seen in
FIG. 102. As represented in these figures, socket block 297 is
mounted the left-hand side of the cement cartridge and air pump 264
compartment. Due to the levering forces imposed by auxiliary
syringe holding frame supporting arm and connecting cable 290 as
would break this bond, auxiliary syringe holding frame supporting
arm and connecting cable socket 296 is joined to the tool with
contacting parts scored or etched and a high bond strength epoxy
cement, such as Aeropoxy ES6209.
[4850] Further to allow optimal viewability and also mounting
stability and quick attachment or detachment, auxiliary syringe
holding frame supporting arm and connecting cable socket 296 has an
internal conformation that is multi-point, generally 6-point or
8-point, in the manner of a wrench socket to also accommodate six
conductors. This configuration allows the tool end of auxiliary
syringe holding frame supporting arm and connecting cable 290 to be
inserted into auxiliary syringe holding frame supporting arm and
connecting cable socket 296 at any of several different angles,
redundant wires (six) and/or electrical terminal pin receptacles
provided so that electrical connection is made regardless of which
rotational orientation is chosen to support this positional
flexibility.
[4851] The portion of the fluid delivery line from socket 296 to
the front of the tool above ejection slot 248 consists of a length
of tubing that is attached alongside the tool with the clips
described below with its upper end plugged into the bottom of
socket 296. When the thickness of the auxiliary cement or other
fluid does not necessitate the use of a delivery line of any
significant diameter, the portion of the line extension clip
mounted alongside the tool can be left in position and sterilized
with ethylene oxide gas (epoxyethane, oxirane, dimethylene oxide)
along with the tool.
[4852] XVI9c(7). Control of Auxiliary Syringe Eject-Ahead or
Eject-After with Determinate Timing
[4853] The electrical components mounted to the back of and used to
control stay insertion tool auxiliary syringe holding frame 284 as
shown in FIGS. 101 thru 103 include surmounting miniature gear head
dc motor 286 and adjustable delay/adjustable interval double or
dual interval relay module 293, such as the Model TGCL Delayed
Interval Relay Timer, Dual Adjustable, made by the Pelco Component
Technologies division, Airotronics Timers and Controls, Cazenovia,
N.Y. Stay insertion tool auxiliary holding frame 284 might
incorporate a separate onboard battery to power dual interval relay
module 293 and motor 286; thus reducing the number of conductors
shown as 301 thru 306 in FIGS. 104 and 105 used to carry current to
and from insertion tool on-board battery 263.
[4854] However, a separate battery incorporated into frame 284,
while adding little to its size or weight, would not eliminate the
need for conductors to carry the holding frame control signal from
the break contact terminals shown in the inset to FIG. 106 as 313
and 314 on the tool to motor 286 and dual interval relay module 293
on holding frame 284 in any event, as would allow all of conductors
301 thru 306 to be eliminated. When auxiliary syringe holding frame
dual delay interval timing relay module 293 break-contacts are
separated by depression of thumb-ring 244, module 293 initiates an
adjustable delay followed by an adjustable ON-time interval.
[4855] Dual delay interval relay module 293 applies the same timing
control regardless of whether the tool has be set to cement-ahead
(cement-before)- or cement follower(cement-during) operation.
Accordingly, adjusting dual delay interval relay module 293 allows
control over the timing of cement ejection and thus the extent of
the stay that is coated. Dual interval relay module 293 being of
the variable external type that is remotely controlled
electrically, usually separate potentiometers with control knob 262
mounted on the tool above recovery electromagnet control knob 262
are used to control the delay and on-time intervals.
[4856] Alernatively, dual delay interval timing relay 293 is set so
that the sum of these intervals corresponds to the average time
that thumbplunger-rod 238 travels downward, and, potentiometer
control knob located above lower control knob 262, which is used to
adjust the field strength of stay retention, retraction, and
recovery electromagnet 242, is used to adjust the relative
proportion within the sum of these component intervals.
[4857] The compound angle and bendability of auxiliary syringe
holding frame supporting arm and connecting cable 290 contribute to
an adjustability essential to obtain a clear view of the operative
field. The conductive pathways from break-contact terminals 313 and
314 to tool end-socket 236 are of the copper etched or printed
circuit (printed or etched wiring board) type, laminated onto the
non-conductive plastic tool, remaining portions of the circuit
completed with wire.
[4858] XVI9c(8). Independent and Subordinated Control of a Stay
Insertion Tool Auxiliary Syringe Holding Frame
[4859] The stay insertion tool is ideally configured to serve as a
mounting platform for tissue cement dispensers whether used in
conjunction with the infixion of stays or not. Specifically, the
configuration allows the operator to access a deep work site
through a small incision, and the tool is ordinarily provided with
a cabled lamp, fiber optic endoscope, angioscope, and/or excimer
laser clipped or lashed alongside. Whereas in dependent or
slave-follower use, current flows through dual interval relay
module 293 and thence directly to motor 286, the switch then having
circuited the current through dual interval relay module 293 and
motor 286 in series, in use of auxiliary syringe holding frame 284
to discharge tissue cement or another therapeutic substance
independently of the tool to which it is mounted, the circuit
bypasses dual delay interval relay module 293, current flowing
directly to motor 286.
[4860] As shown in FIGS. 87, 88, and 102, switch control buttons,
such as slave-follower-to-independent and the reverse function
switch are mounted on the outer side of thumb-ring 244. The wires
run through thumb plunger rod 238 to hexagonal auxiliary syringe
holding frame supporting arm and connecting cable socket 296 shown
in FIG. 106 with inset enlargement. This switch may be one of
several, where each switch is used to control a different auxiliary
device, whether a laser, suction line, or an auxiliary syringe
holder. In the slave or passive follower control mode,
thumb-switches 309 thru 312 seen in FIGS. 87, 88, and 102 are not
used, dual interval relay module 293 locking the operation of the
auxiliary syringe holding frame 284 to the stay ejection cycle of
the tool in timing function.
[4861] Several miniature switch types are suitable, to include
bounceless (debounced) toggle, rocker, and slide types; however,
those that provide a depressible button are preferred as
expeditious. As shown in FIGS. 87, 88, and 102, so that the
operator can move button switches 309 thru 312 as desired, the
mounting of this and other miniature switches encircle as to be
slidable or shiftably clampable along and rotatable around
thumb-ring 244. The mounting of thumb-switches 309 thru 312 can be
by means of fastening the switch to a miniature clamp ferrule of
the screw-tightened kind made, for example, by the Wenzhou Jubang
Light Industry Machine Company, Wenzhou, China.
[4862] However, for quicker and less distracting repositioning
midprocedurally, a spring loaded shaft or spring steel pinch-type
clamp ferrule that allows instant release and reattachment is
preferred to lever or screw tightened types. The bases of
thumb-switches 309 thru 312 are fastened to the outer surface of
the slidable clamp ferrules with an adhesive specifically chosen
for the metal or polymer materials at the interface to be bonded
Lining the internal surface of the clamp ferrule with an elastomer
will take up any space between the external surface of thumb-ring
244 and the facing surface of the slidable clamp ferrule, thus
reducing any tendency of the switch to rock save by a completely
exacting fit.
[4863] The motor or motors wired in series following dual interval
relay module 293, independent control shunts the relay to control
the motor or motos directly. The switch used should toggle, rock,
or slide between independent and slave control positions, and
additionally allow moderate thumb pressure placed upon the spring
loaded switch while set to independent control to directly, that
is, by shunting around dual interval relay module 293, actuate
holder motor 286. Unlike a flange or straight handle index and
middle finger stops, finger-rings 232 and 249 seen in FIG. 88 make
it possible for the the operator to remove his thumb from
thumb-ring 244 to actuate switches 309 thru 312 by feel.
[4864] To this end, each of the switches 309 thru 312 are slid
along thumb-ring 244 to the position of most comfort with least
movement required to use these. As indicated when more auxiliary
functions operated by means of an electrical switch are attached to
the tool, each switch is of the same kind, any function being
instantly selectable and controllable through a slight movement of
the thumb. Holders can be mounted to both sides of the tool. This
allows, for example, the application of medication under
independent or direct operator control from the syringe or syringes
to one side, and the application of tissue sealant from the syringe
or syringes to the other side under tool slave-follower
control.
[4865] Switches for auxiliary syringe holder 284 are mounted to the
side of thumb-ring 244 to which the auxiliary syringe holder is
attached, those for the side shown in FIG. 102 shown therein as 309
and 310, with those for use with a second auxiliary syringe holder
attached to the other side seen in FIG. 88 as 311 and 312. Several
switches can be mounted thus and slid for convenient use by the
thumb, one switch each for each auxiliary device, such as an
aspirator or laser, attached to the stay insertion tool that is
electrically operated. The operator chooses the side and position
of the switches for greatest right or left hand comfort and
clarity.
[4866] For quick connect and quick disconnect capability, the upper
end of auxiliary syringe holding frame 284 supporting arm and
connecting cable 290 is pressed over the lower end of syringe
mixing nozzle 292 shown in FIGS. 102 and 103, and the bottom end
inserted into auxiliary syringe holding frame supporting arm and
connecting cable socket 296, shown in FIG. 106. To allow socket 296
to be found instantly by touch, socket block 297 is mounted so that
socket 296 stands proud at an incline from the side of the tool.
Socket 296 is preferably molded integrally with, but can be bonded,
using a strong and steam autoclave resistant adhesive to the rear
side of inmate cement air pump and refill cartridge compartment
264, as shown in FIG. 102, a contralateral socket block if
provided, bonded to the back side of the tool as depicted in FIG.
106.
[4867] A left-hand auxiliary syringe holding frame mounted
contralateral to that shown to the right in FIG. 102 also has its
own delivery line running down the opposite side of the tool as
depicted in FIG. 106. Shown in FIG. 102, auxiliary syringe holding
frame 284 is connected at the right-hand side of the stay insertion
tool. The stay insertion tool can provide right and left-hand line
entry sockets shown as 296 in FIG. 106 for attachment of auxiliary
syringe frame 284 supporting arm and connecting cable 290 at either
or both sides of the tool. Ordinarily, either supporting arm and
connecting cable 290 provides a single lumen, the outflow of
compatible contents from the syringes inserted into frame 284 at
the moment transmitted together.
[4868] That is, compatible contents of plural auxiliary syringes
can be conveyed together through the ordinarily single lumen shown
in FIGS. 102 thru 105 of auxiliary syringe holding frame 284
supporting arm and connecting cable 290 connected at that
respective syringe side of the stay insertion tool. Since the
syringe contents to a given side of the stay insertion tool would
be mixed when entering a common line, keeping these separate
necessitates that line entry socket 296 and line 298 continue the
luminal exclusivity and that syringes be inserted and removed from
frame 284 as necessary.
[4869] Outer casing or conduit 299 shown in FIGS. 104 and 105 of
auxiliary syringe frame 284 supporting arm and connecting cable 290
is not continued down to ejection slot 248, which is usually
reserved for the ejection synchronized outflow of cyanoacrylate
cement from pump 264. Instead, small ring nonallergenic elastic
bands or small wire ties are used to position the outlet of each
line about the distal or working end of the stay insertion
tool.
[4870] XVI10. Binding of Lines and Cables Alongside the Stay
Insertion Tool
[4871] XVI10a. Uses of Stay Insertion Tool Mounting Clips and
Bands
[4872] Stay cement coating pump 264 and line 260 to eject or emit
just above ejection slot 248 beneath ejection slot-overextended
delivery line 260 tip 269 is not by attachment; these are integral
parts of the tool. Incorporation whether by primary molding or
secondary bonding is permanent. By contrast, the lines leading down
to the working end of the tool from auxiliary syringes and the
cables of devices such as angioscopes, laser pointers, aspiration
lines, plain water or therapeutic solution irrigation lines,
excimer ablation lasers, vortex cold air guns, and so on, when
necessary, must be freely attachable and detachable from the
tool.
[4873] When the tool is used for a single or similar procedures,
these lines and attachments are more securely attached alongside
the shaft of the stay insertion tool by means of clips suitable for
long-term or permanent attachment. When any of a number of
different lines and cables may need to be interchangeably fastened
alongside the tool, small nonallergenic elastic rings or wire ties
least add to the diameter of the tool at the working end, and low
in cost, can be quickly snipped off and discarded. Except for the
distal cinching of the adhesive delivery lines above the stay
ejection slot, which can be accomplished simply with an elastic
band to allow an auxiliary line to discharge beside or with a small
length of bent tubing attached at the distal end, just to the front
of the slot when shifted over with the end of a probe, attachment
of the delivery lines to the tool is usually by means of clips.
[4874] Clips are mounted to the sides of the insertion tool to
allow the permanent or semipermanent attachment of a variety of
auxiliary devices alongside, that is, in long coaxial relation to
the tool shaft. These would typically include rigid boroscopes or
flexible fiberoptic endoscopes, angioscopes, ablation and
light-activated surgical protein solder lasers, a suction
(aspiration) and/or irrigation line, or a `cooling` catheter for
delivering hot or cold air from a vortex tube, or cold gas from a
compressed and liqified cold air cylinder. Vortex tube-based `cold`
air guns have onboard (internal) controls. Cabled devices usually
have a cable that leads to a control console from which the cable
may or may not be disconnectable, or if connectable is so at the
console and remote from the tool.
[4875] When the cabled device is always needed, as when the tool is
used to repeatedly perform the same procedure, the cable can be
permanently fastened alongside the tool with non-quick release
clips. Otherwise, unless the cable can be quickly detached from the
tool or a joint introduced in the cable for conection at the top of
the tool, the tool must remain tethered to the console, even when
the cabled device is not in use. For most cabled devices, the
introduction of a joint poses considerable expense. Rather than the
introduction of a joint that would leave the distal portion of the
cable permanently occupying a position on the tool, making that
position unavailable for attaching any other line or cable, quick
disconnectibility is provided through the use of quick release
clips or elastic bands.
[4876] Unlike an auxiliary syringe holder as addressed above in the
section entitled Use of Commercial Syringes and Extension Tubes,
controls for autonomous apparatus, at least when these are
obtrusive, are not mounted on the insertion tool, the availability
of an assistant assumed. Clips are more suited to use with stay
insertion tools that are limited to a repeated procedure, so that
the number of lines and their location relative to stay ejection
slot 248 is consistent. Otherwise, small nonallergenic elastic
bands are used, as addressed in the paragraph to follow. For this
reason, and because clips are familiar, clips have been omitted
from the drawing figures.
[4877] The number of cabled devices that can be run alongside the
stay insertion tool is neither indicated by or limited to the front
or side clips provided; additional devices can be mounted with
tape, ties, or nonallergenic elastic bands, for example, the
determinant being the need to avoid hindrance in access to the work
site. Controls for lines attached to the tool that can be
manipulated by touch alone and clamped directlly onto the gown or
to a belt. With a lamp or endoscope and cold and hot air line
attached, for example, the stay insertion tool can be used to apply
heat or cold to a ductus from without. Because thrombogenic
temperatures cannot be avoided, doing this with an artery assumes
that a platelet blocker or a vein that an anticoagulant has been
administered.
[4878] However, such medication is always administered in
interventional procedures, and here, because no foreign object is
left in the vessel, the need for such medication should not extend
beyond the periprocedural. Any lines used to deliver or remove
materials from the work site arrive and depart at the top of the
tool through "stay away" extended grommets of a nonallergenic
elastic of the kind seen in steam irons or a wire helix as not to
interfere with passing the tool through the entry wound and with
the lines least obtrusive when extended over the patient to the
opposite side. Fasteners for holding lines alongside the tool can
be any of several types.
[4879] One is a conventional spring clutching rounded arm type
clip, such as the type used to fasten wires to circuit boards, or
"body clips" made, for example, by Traxxas, L. P., Plano, Tex.
Other types are miniature side or top acceptance cable clamps or
wire phone clips made of stainless spring steel, plastic with
pressure sensitive adhesive backing, multiple wire to wall
fastening strips, strips of tape, or small ring gauge nonallergenic
elastic bands. Of these, small bands are preferred as allowing any
number of lines in any arrangement to be held against the sides of
the stay insertion tool, and allowing these to be rotated about the
perimeter so that the substance discharged can be made to emit at a
certain location in relation to ejection slot 248.
[4880] Clips for holding can be either of two types. The first type
are conventional spring clutching rounded arm types, such as the
type used to fasten wires to circuit boards "body clips" made, for
example, by Traxxas, L. P., Plano, Tex., or side or top acceptance
clips made of stainless spring steel. The latter are made in the
form of simple curved leaf springs fastened at one end by a rivet
to allow rotation and having a short length to the front that is
bent slightly upward to assist in lifting each spring clip up and
over the tube to be inserted beneath it.
[4881] The clips ideally include rounded arch-shaped elevations
that have been sized to hold down tubes of at least the two most
common size ranges, to include microcatheters and rigid endoscopes.
The U-configured type spring clip that clutches about the tube is
unsuitable as little adaptive to more than minor changes in the
diameter of the tube to be held. Various tubular attachments are
discussed below. Stainless spring steel can be obtained from
numerous companies, to include Sandvik Materials Technology,
Sandviken, Sweden, and finished clips of the kind described can be
provided by numerous companies, to include the Newcomb Spring
Corporation, Decatur, Ga.
[4882] XVI10b. Use of Stay Insertion Tool Side Mounting Clips to
Laterally Juxtaposition (Fasten Alongside) an Endoscope
[4883] An endoscope (medical borescope) or an angioscope, whether
rigid or a fiberscope, with viewing end (objective lens) at the
foot of the stay instion tool can allow the working area and the
functioning of the tool to be observed through a small entry wound.
Approaching from outside the ductus, stay insertion is best when
the insertion arc is in expansion. For work in the arterial tree,
viewing the rhythm of the systoles, to which peak the insertion of
the stay is best timed, is made easier. Advancement in rigid
endoscopes allow a sufficient field of vision or the view to be
manipulated with mirrors and/or prisms, and an inline plate with
flat screen monitor and manipulation controls is ergonomically
advantageous compared to the use of a video monitor. The means for
adapting to a pulse that is too fast and/or irregular are addressed
above in the section entitled Motional Stabilization of the Implant
Insertion Site.
[4884] The diameter of such endoscopes, made, for example, by
Ethicon Endosurgery, Cincinnati, Ohio, is one centimeter (see, for
example, Kim, K., Kim, D., Matsumiya, K., Kobayashi, E., and Dohi,
T. 2005. "Wide FOV [Field of Vision] Wedge Prism Endoscope,"
Institute of Electrical and Electronics Engineers Engineering in
Medicine and Biology Society Conference Proceedings 6:5758-5761;
Ryndin, I., Lukasewycz, S., Hoffman, N., Nakib, N. A., Best, S.,
and Monga, M. 2005. "Impact of Heads-up Display Imaging on
Endoscopic Task Performance," Journal of Endourology 19(8):964-967;
Kobayashi, E., Sakuma, I., Konishi, K., Hashizume, M., and Dohi, T.
2004. "A Robotic Wide-angle View Endoscope Using Wedge Prisms,"
Surgical Endoscopy 18(9):1396-1399; Schier, F., Beyerlein, S., and
Gauderer, M. W. 2002 "Imaging for Endoscopic Surgery: New
Developments Applicable to Pediatric Surgical Interventions,"
Pediatric Surgery International 18(5-6):459-462; Kobayashi, E.,
Daeyong, K., Sakuma, I., and Dohi, T. 2001. "A New Wide-angle View
Endoscopic Robot Using Wedge Prisms," Computer Assisted Radiology
and Surgery 1230:149-153). Some current wireless video fiberscopes
(flexible boroscopes), such as the Tactical Electronics and
Military Supply L.L.C., Broken Arrow, Okla. Model VFS 2 can be
attached.
[4885] Examination of the insertion tool when not functioning
smoothly is generally determined and any build up of adhesive
accomplished by withdrawal of the tool from the work area for
direct viewing, which the tranparency of the materials used allows.
When the entry wound is large enough, the overhead lamps and head
lamp should provide adequate illumination down through the entry
wound, and binocular telescopes should afford sufficient
magnification; however, to minimize trauma, means are applied to
allow access and visibility with the least incision. Using the side
mounting clips, small downward directed lamp that draws power from
the internal battery can be attached to the side of the tool.
[4886] An endoscope can, however, provide a more detailed view of
the work area. To allow a closer view, a conventional flexible or
fiber optic endoscope with light delivery system can be affixed
alongside the tool. To attach the endoscope, the clips are
positioned at intervals down the sides of the stay insertion tool.
The endoscope can target the ductus to receive the stay implants or
to discover that adhesive is not properly applied before this
becomes apparent through clogging sensed tactually, the front edge
of the ejection slot roof The roof of ejection slot stay ejection
slot 248 and the sides of the insertion tool are transparent,
allowing the reflective liquid adhesive to be distinguished from
the flat tantalum coating of the stays.
[4887] XVI10c. Use of Stay Insertion Tool Side Mounting Clips to
Juxtaposition (Fasten Alongside) a Vacuum (Aspiration, Suction)
Line
[4888] The incorporation into the stay inserter of an onboard
wholly contained miniature aspirator pump to drive a closed circuit
suction line with suction inlet at the foot of the tool to allow
drawing a collapsed or receding near ductus wall up to the foot or
sole of the inserter with the object of eliminating a piped
aspiration line is discounted as constantly fouled by the entry of
body fluids. Clips on the side of the stay insertion tool opposite
those for the attachment of an endoscope allow a vacuum
(aspiration, suction) line to be fastened alongside the tool. While
the suction line is available for the conventional removal of fluid
that obscures the view, its primary a means for supporting the
ductus so that it can be implanted without collapsing beneath the
tool as discussed above in the section entitled Arcuate Stent-stays
(Stays, Stent-ribs, Ribs) or Stays for Use with Stent-jackets. When
suction works, it eliminates the need to station a muzzle-head at
the level of implantation as, thus preserving a major advantage in
the use of stays as opposed to miniballs.
[4889] To distribute the force of suction on the outer surface of
the ductus to be treated, the distal soft tip of the suction tube
may be flared outward towards the sides as aligned to the long axis
of the ductus. A collapsed or collapsing ductus can then be drawn
up toward the sole of the tool to allow the stays to be inserted to
the depth sought. The disposal of used vacuum tubes and control of
the vacuum level as, for example, by means of a magnetoresistive or
Hall effect flow meter, lies outside the present scope. Bands and
clips for fastening various kinds of lines, such as those of cold
air gun and vacuum lines alongside the stay insertion tool are
addressed in the section to follow.
[4890] A small-gauge length of tubing can, for example, be secured
to the side of the insertion tool with its outlet fixed in position
beside the stay ejection slot. This tube can be transferred from
the cold or hot air outlet of a vortex tube, or `cold air gun,` for
example, to a vacuum pump to serve as a suction (aspiration) line,
for example. This can be accomplished either by redirecting or
switching the proximal end of the tube through an air switch valve
or by physically disconnecting the end of the tube and reconnecting
it to the pump.
[4891] The couplings (joints, unions) and valves for such purpose
well known. As specified in the section above entitled Turret-motor
Operational Modes, reducing the mobility and the level of chemical
activity in the tissue to be implanted can allow greater precision
and a lessening if not the avoidance of unwanted immediate and
postprocedural reactions such as swelling. Although the use of
stays should not result in contact with the intima, the
stabilization afforded by cold pertains to the media as well. A
cold air gun or supply line in the form of a narrow hose or tube
from a source of cold air allows the tissue for treatment to be
stabilized.
[4892] XVI10d. Use of Stay Insertion Tool Side Mounting Clips to
Juxtaposition (Fasten Alongside) a CO.sub.2 Cylinder or Cold Air
Gun Line
[4893] Unlike ballistic implantation, where the exit velocity and
not the restorative force of the thumb plunger rod return spring
245 in a control syringe-configured stay insertion tool as shown in
FIGS. 87 and 88 or the direct tactile control of a
pistol-configured tool as shown in FIG. 89 determines the force and
depth of penetration, the increased hardness of the tissue has
little consequence with a hand tool. Excessive or inadequate
restorative force of the spring in a control syringe-configured
tool is easily adjusted with the thumb. Temperature change with or
without application of a supporting solution can sometimes be used
to affect tissue hardness.
[4894] To counteract the retardation in the rate of curing of the
tissue sealant or adhesive applied by the stay insertion tool
during implantation (addressed above) that chilling would also
effect, an immediate source of warm air to follow the cold air is
necessary. Furthermore, an immediate remedy should be available if
through human error the temperature were set so low that it would
freeze and not just chill tissue. Quickly returning the tissue to a
warmer temperature is accomplished by switching the air supply line
from the cold to the hot outlet of the same cold air gun, existing
means for accomplishing such numerous.
[4895] Provided an assistant is present, for this immediate
reversibility between cold and hot temperatures, the use of a cold
air gun is preferred. The unassisted use of cold gas is most easily
and least divertingly obtained by fastening a medical cryospray
gun, can, or CO.sub.2 cartridge with attached nozzle and connector
to the proximal end of a delivery line (length of catheter) clipped
alongside the insertion tool. Fastening the gun or can at the side
or front of the gown and allowing sufficient slack, tethering
hindrance and the need for more than touch alone are virtually
eliminated.
[4896] XVI11. Use of Stay Insertion Tool
[4897] The use of stay insertion tool mounting clips is addressed
above in separate sections. Stay retention, retraction, and
recovery electromagnet 242 and magnet controls 262 are tested on a
small ferrous metal object that poses the same resisance to
attraction. Any auxiliary lines, whether for temperature-changing
(`cooling` catheter), aspiratiion, or a cabled device such as an
endoscope cable, lamp, or a holder and delivery line for an
auxiliary dual-cartridge as addressed above in the section entitled
Stay Insertion Tool Auxiliary Syringes are attached and tested.
When cyanoacrylate cement is to be used, a cartridge containing
acetic acid can be used first to flush through the delivery
line.
[4898] As a retardant, acetic acid reduces the tendency for the
cement to cake and clog at the distal tip. To avoid wasting stays,
this and the step that follows must done before a clip of stays is
introduced into the stay chamber (stay bay). Shown in FIG. 87,
surgical cement, a fluid pharmaceutical or therapeutic, medication,
tissue hardener, or fixative refill cartridge 236 is inserted into
the refill cartridge compartment 235, lower end first. Pushing the
upper end of refill cartridge 236 into refill cartridge compartment
235 causes hollow tissue cement or therapeutic fluid delivery line
260 inlet hollow puncture needle 237, which protrudes up through
the floor of refill cartridge compartment 235 at the inception or
upper end of the surgical cement or other fluid supply line 260, to
puncture the bottom of the refill cartridge 236 much as does
loading a CO.sub.2 cartridge into an airgun.
[4899] In FIGS. 87 and 90, tissue cement or therapeutic fluid
delivery line 260 conducts fluid from fluid refill cartridge 236
down the front of the stay insertion tool to an overhang at the
stay ejection slot 248. Repeatedly depressing thumb rod ring 244
and thus thumb rod 238 when rod 238 is engaged with pump piston
233--or with the pistol-configured embodiment shown in FIG.
89--repeatedly pulling trigger 261, causes cement compartment pump
piston 233, to advance cement or other fluid 236 down through fluid
feed line 260 in increments until cement begins to emerge at the
lower or distal end of fluid feed line 260 to coat each stay as it
is ejected.
[4900] The tip of the adhesive line is wiped clean with a sterile
acetone-soaked cloth. To allow refill cartridge 236 to be inserted
into refill cartridge compartment 235 easily, the top of refill
cartridge 236 and/or upper ledge or lip of fluid refill cartridge
compartment 235 interface or meet at a slight incline. Since a
separate syringe can be connected directly to inlet hollow puncture
needle 237 or preliminary cartridges used to prime fluid feed line
260 so that fluid will emerge with the first stay to be ejected,
the capacity of refill cartridge 236 in refill cartridge
compartment 235 is not governed by the volume of fluid needed to
fill fluid feed line 260 before stays 231 are coated.
[4901] Such a separate syringe or multiple refill cartridges 236
can be used to preload, prime, or flush fluid feed line 260. The
lower or distal portion of feed line 260 passes through the entry
incision, and to allow the incision to be as small as practicable
and take up the least volume of fluid from the smallest practicable
refill cartridge 236, is held to the smallest usable diameter. The
cyanoacrylate cement loaded is usually light in viscosity and
consistent with a feed line of slightly greater than capillary
diameter. If necessary, fluid feed line 260 is flushed of set
cement by removal from the patient and insertion of a refill
cartridge 236 in refill cartridge compartment 235 containing
acetone, which is run through the line.
[4902] A cement cartridge is then fully discharged through the line
before the tool is reintroduced into the patient. A clip or strip
of stays 231 is inserted into stay refill cartridge compartment
250. The setting and response of dual interval relay module 293 is
checked and if necessary, adjusted. Two or more stays are ejected
to test the tool for properly coordinated timing between stay and
cement ejection before introducing the working end of the insertion
tool through the entry wound. If necessary, the adhesive ejection
timing slide valve in the side of the cement air pump and refill
cartridge holding chamber (cylinder) is used to adjust the moment
of inception for adhesive ejection.
[4903] If the tool still does not perform correctly, the
transparent tool allows the cause of malfunction to be directly
observed. If used, auxiliary syringes in holding frames must be
charged (filled) down to the exit tip or tips. The setting on an
attached commercial tissue sealant or medication holding frame or
frames must be tested, as must any other attachments used. As
applicable, the timing coordination between an auxiliary syringe or
syringes in relation to the stay ejection cycle and another holding
frame if present must be tested to the accuracy actually needed.
The amount of substance released determined by the duration of
discharge, timing must be adjusted to control this factor as well
as to properly coordinate the action of the holding frame or frames
with that of the tool.
[4904] A small diameter endoscope and aspirator line will almost
always be used and should be pretested. When the preliminary tests
described below for inter- and intralaminar separation are omitted,
a dental probe-hook is should still be used to evaluate the pliancy
of the ductus. Upon completion of the procedure, the stay
refill-strip and adhesive cartridge are removed, discarded, and
inmate adhesive delivery line or tube 260 flushed through with a
refill cartridge containing acetone or a commercial long chain
cyanocrylate glue remover or solvent such as Duro.RTM. Super Glue
Remover, or acetone, which may be in the form of nail polish
remover.
[4905] Alternatively, the line can be flushed through by placing
the distal end of a tube connected to a syringe containing the
solvent over stay cement supply feed line or applicator tube 260
inlet hollow puncture needle 237. The tool must always be
sterilized immediately following and preceding use. Referring to
FIG. 91, taking care to slip toe 253 through the entry wound
(incision, portal) first, the stay insertion tool is passed through
the entry wound and positioned on the ductus with toe 253 and
arcuate bottom of the working end flush. The depth of implantation
is set by adjusting the downward force on the ductus.
[4906] When properly employed on a ductus of the prescribed
diameter for the specific tool used, setting positioning sole 254
with no more downward force than is necessary to keep the tool from
shifting will achieve subadventitial placement. The attachment of a
suction hose (aspiration line) as discussed above in the section
entitled Use of Stay Insertion Tool Side Mounting Clips to
Laterally Juxtaposition (Fasten Alongside) a Vacuum (Aspiration,
Suction) Line and cold air line as discussed above in the section
entitled Use of Stay Insertion Tool Side Mounting Clips to
Laterally Juxtaposition (Fasten Alongside) a Cold Air Gun Line can
assist in reducing any tendency for an empty ductus to collapse
under the tool.
[4907] The tool can be used to direct cold or hot air at the
outside of a ductus through the incision made to insert the stays
and/or the stent-jacket, and since it can be quickly switched
between hot and cold air (or gas), is conveniently used thus even
when the intraductal implants are miniballs. Applying somewhat more
force will cause the stays to enter more deeply into the media as
is unavoidable should upon testing as described under the section
below entitled Site-test on Extraluminal Approach for Intra- or
Inter-laminar Separation (Delamination) the adventitia reveal a
propensity to delaminate from the subjacent tunic.
[4908] Whenever the inmate cyanoacrylate or an auxiliary syringe
containing tissue sealant is used to automatically apply cement to
each stay as it exits, retracting a stay that failed to enter true
back into the ejection slot would introduce cement into and likely
clog the ejection slot. However, once a stay has completely
ejected, even though turning up the magnetic field strength
(battery current) allows it to be withdrawn and retained on the
tool, the stay cannot be returned to the attitude necessary to
cause it to reenter into the ejection slot; gravity pulls the stay
downward. precluding reverse reentry.
[4909] No attempt should be made to reenter the stay into the
ejection slot, and the operator should not allow the restorative
force of the thumb plunger spring to cause the stay to drop off the
end of the tool before the tool has been completely withdrawn from
the body and the clingling stay removed. The front of the ejection
slot should then be cleaned of any cement. Any concern that the
tool may not eject properly should prompt the discharge of a test
stay. The amount of downward force might be quantified with a built
in digital force gauge or scale; however, clinical experience is
preferable, the recommendation of specific forces for variable
conditions ill advised. While improbable, a ductus that slides or
rolls aside despite the indented sole of the tool is stabilized
with the aid of a probe.
[4910] The stay is inserted. To tamp down and seal the incision,
the tool is moved slightly forward or reversed, and a slight
downward force applied. If implantation is suspected to be
mispositioned prior to ejection, the recall magnet is energized to
withdraw the stay and the tool tested outside the body. The
operator confirms the successful sealing of each before proceeding
to the next. If the ductus stay insertion incision is not sealed,
the tool is removed and a long chain methacrylate adhesive
introduced into the ductus stay insertion incision by means of a
microcatheter as described above in the section entitled 378.3 or
at the tip of a a narrow probe. The stay insetion tool is tested
outside the body.
[4911] In situ, transparency serves not only to improve the
viewability of the work area from different angles to confirm
proper contact and circumferential relation of the tool sole to the
ductus surface, but with the aid of an optionally attachable
endoscope, allows the stays to be observed as these pass through
stay ejection slot shown in FIG. 90 as 248. Should the ductus to be
stay-implanted be collapsed or collapse under the stay insertion
tool or waver due to smooth muscle action, a vacuum (aspiration,
suction) line fastened to the side of the tool opposite the
endoscope is used to better stabilize and achieve the tool-ductus
relation required. In some instances, an artery may require to be
immobilized with a forceps or hemostat.
[4912] XVII. Testing and Tests
[4913] XVIII. Need of a Means for Testing the Resistance to
Puncture, Perforation, and Delamination of Tissue Requiring
Treatment
[4914] Testing pertains to equipment manufacture and its
application in the clinic or catheter laboratory. Quality control
testing during and after manufacture adheres to established medical
equipment manufacturing procedures. As in differential diagnosis
and therapy generally, the number of variables is large, some may
be unknown, and if known, difficult or impossible to gauge, and
more difficult still to gauge in context. To some extent, the
variables will be peculiar to the individual patient, whose
condition overall may add comorbidities, and as always,
nonawareness of or discounting a significant variable could result
in a misapplication of data. Data that can be immediately put to
practical use with reasonable confidence is sought, and data
collected and tested ex vivo with precision equipment in a
laboratory disregarded despite its theoretical value.
[4915] The results of such testing appear in the literature.
Preprocedural and postprocedural examination is with noninvasive
imaging equipment, intravascular ultrasound (which is invasive)
used only when indicated by the imaging results and/or the
prospective procedure is invasive in any event. The diagnosis
spoken of here is that pertinent to mechanical properties of tissue
under evaluation for ballistic implantation; however, the
development of sensors that allow chemical analysis to identify
different conditions of disease expands the zone of diagnostic
utility. The midprocedural use of intravascular ultrasound allows
susceptibility to and de facto intramural delamination to be
evaluated before and after treatment.
[4916] Provided treatment can is accomplished and obtain the result
needed quickly, the need for a followup invasive procedure is
eliminated. Delamination, for example, can be accomplished by
passing a fine aspiration line leading to a highly sensitive vacuum
gauge able to distinguish fine differences in vacuum pressure
through the access incision and up against the adventitia or
perivascular tissue adherent thereto. Provided examination can be
completed before a serious risk of ischemia obtains,the prospective
radially outward retractive force to be exerted by a stent-jacket,
for example, is applied, preferably at several points, the
consequences observed over an interval, another catheter with
hypotube used to deliver therapy, and the intravascular ultrasound
used to view the result.
[4917] Such testing is made more dependable through the use of an
aspiration catheter equipped with a suction pad having aspirating
holes spaced as does the prospective stent-jacket. The delamination
can be responded to by using wide cyanoacrylate cement coated
stays, time allowed for the cement to set, and the delamination
reexamined. Aternative methods for responding to delaminations, to
include the use of miniballs coated with a lower temperature
denatured or flowed protein solder and the application of heat are
set forth above.
[4918] At least for procedures that will necessitate endolminal
entry, the use of a multibarrel radial discharge barrel-assembly
for diagnosis and therapy, as a tool in itself and regardless of
whether use thus is followed by miniball discharge, is
considerable, and rises in proportion to the extent of the software
support afforded. While the testing and treatment accomplished are
ordinarily intended to precede ballistic implantation using the
same barrel-assembly, a multibarrel radial discharge
barrel-assembly, especially one driven by an automatic positional
control system, can serve purely as a diagnostic and/or therapeutic
tool capable of immediate treatment responsive to the point to
point findings obtained.
[4919] This integral diagnostic and therapeutic capability is not
shared byconventional means such as balloon catheters and
rotational atherectomizers, for example, which must rely upon the
support of imaging means incapable of providing treatment and may,
as would therapeutic means such as a laser or rotatory ablation
device, necessitate separate endoluminal entry. Machine positional
control allows the muzzle-head to immediately and accurately return
to the point tested with a therapeutic catheter or an exit-hole for
discharge. Diagnostic software can eliminate the time a human
operator or assistant would need to convert each test finding into
the appropriate therapeutic response and then bring the therapeutic
catheter to the correct position.
[4920] The positional control system provides quick and accurate
repositioning of the muzzle-head to each point tested for
treatment, and if intended, implantation, with followup testing at
each point if desired. Even when the system is operated manually in
a semiautomatic mode to diagnose and treat a simple condition, the
advancement and retraction of injection catheters, for example, can
be controlled by the controller as an auxiliary function using
conventional miniature electrically or pneumatically operated
pistons. Eliminating direct control by the operator eliminates
human error that could, for example, allow the tip of an injection
needle to remain projected during transluminal movement, and
further contribute to making the barrel-assembly a potent tool for
diagnosis and treatment.
[4921] Operated under fully automatic control by coordinated
diagnostic, therapeutic decision-making, and critical path
software, the barrel-assembly is instantly and accurately
repositioned in a fully coordinated sequence among a plurality of
points to be tested and treated. The critical path software
distinguishes among the points so that each is tested and treated
independently and coherently; however, by coordinating the point to
point sequence of movements according to least overall time
criteria, the software optimizes the efficiency of motion control
so that the separate points are in effect, treated concurrently,
the resultant action blended as to appear continuous.
[4922] Software to function thus can be devised for a specific
syndrome or condition, such as ileocolitis or atherosclerosis, and
reduces the response and procedural times that a human operator
could achieve to a degree that makes treatment thus practicable;
that is, the time a human operator with the support of assistants
would need to accomplish the same end would usually disallow such a
procedure as too complicated, too lengthy, and too expensive. The
testing addressed here is that intraprocedural for immediate
application to implant insertion and that postinsertion to confirm
successful insertion. Quantitative findings are intended as a
simple adjunct to clinical judgment, and not to suggest a level of
confidence that no data, regardless of its precision, complexity,
or cost, could provide.
[4923] The section above entitled Airguns contains some information
on converting test values into equivalent exit velocities. Because
diseased tissue considerably exceeds in range of variation that
found in normal tissue effectively negating the data anyway, and
because the tissue may be in transition, that is, undergoing change
or metaplasia, means for testing the mechanical properties of the
tissue to be treated are accomplished using the simplest and least
expensive equipment available. To this end, stay insertion tools
and barrel-assemblies can carry onboard the testing equipment
needed for their use, either by attachment or incorporation.
[4924] Either can attach an angioscope to allow a view that is
clear enough to distinguish surface indentation and ductus wall
elasticity, for example. If that relation is consistent and no
visual evidence to the contrary is seen over the segment, then
elasticity is inferred on the basis of indentation. Testing
necessitates additional time and money and when possible is avoided
entirely or kept to the minimum, using relatively simple and
inexpensive means for obtaining essential measurements. Generally,
the placement of wide stays coated with cyanoacrylate cement seldom
warrants testing for tunical or intratunical delamination or for
pull-through; a quick probing to rule out malacotic areas should be
all that is needed.
[4925] A ductus too malacotic to retain these over time despite
treatment with a tissue hardening or sclerosing agent indicates the
need for replacement with a graft. When testing is felt warranted,
a stay insertion tool equipped as addressed above in the section
entitled Stay Insertion Tools, can itself be used to test for
extraluminal approach or a mechanical force and indentation service
catheter can be passed through the incision at the body surface
Stent-jacket resilience is inferred on an intuitive basis using the
information available, to include visual and any acquired through
simple testing to determine tissue hardness. Preprocedural imaging
that does not furnish mechaniical information to indicate implant
suitability and retainability is of little practical value for the
purpose at hand.
[4926] Concerns that a stent-jacket may lack sufficient flexibility
for close compliance with the distention and contraction of the
ductus is better responded to by using a more pliant jacket than by
initiating an intricate and time-consuming investigation; the use
of intravascular ultrasound to determine arterial wall elasticity
in relation to blood pressure, for example, measures a mechanical
property with a potential benefit only as time and money permit.
For preinsertion or pre-placement testing whether extraluminal to
place stays or endoluminal to place miniballs, testing is
preferably by means of relatively inexpensive catheteric mechanical
and magnetic sensing probes. These include catheteric force gauge
and magnetometer probes, and preferably, probes that combine these
functions, eliminating the need to withdraw one tool and insert
another.
[4927] Such consolidation of functions has the additional advantage
of making possible the immediate interconvertibility between the
different types of data when necessary. Means that provide
positional as well as mechanical information provide such
information with less time, complexity, and expense. With
extraluminal approach, the probe, usually attached alongside the
stay insertion tool, is inserted through the access incision at the
body surface and applied to the adventitia. With endoluminal
approach, the probe is passed through an unused barrel-tube as
service-channel or the central channel of the barrel-assembly,
thereby eliminating the need for entry more than once through the
entry wound.
[4928] Routine postprocedural testing where no adverse sequelae
have appeard is by noninvasive imaging. Whereas angioscopes,
aspiration lines connected to vacuum gauges, and combination
magnetometer/force-measurement probes, for example, can be passed
through an available barrel-tube as service-channel or through the
central channel, an intravascular ultrasound probe and/or excimer
laser must be passed down the central channel to look out coaxially
at the center of the nose. Larger gauge barrel-assemblies can
incorporate an intravascular ultrasound probe and/or excimer laser
in side by side relation, the degree of abaxiality
inconsequential.
[4929] The ability to incorporate catheteric probes diminishes with
decreasing gauge according to the miniaturization that might be
achieved; however, the coronary arteries of a neonate, tiny and
end-arterial excepted, small vessels do not require treatment thus.
Stay insertion tools can attach angioscopes, aspiration lines, and
combination magnetometer/force-measurement probes, for example.
Rather than to allow the tool to be tethered by the remote
connections of these, the lines attach to connectors at the tool.
The use of costly imaging midprocedurally is avoided. For example,
when stays are used without an ablation or an angioplasty,
intravascular ultrasound is the only circumstance that necessitates
luminal entry.
[4930] By the same token, since the lumen must be entered to place
miniballs in any event, intravascular ultrasound may, however,
prove of value in endoluminal approach by revealing conditions that
would increase susceptibility or resistance to penetration,
delamination, or pull-through. Intravascular ultrasound catheters
have achieved a thinness of a few French that allows these to be
passed down the central channel or an edge-discharge muzzle-head so
that the need for separate entry for imaging and therapy is
eliminated. Combination-form barrel-assemblies can incorporate or
allow the insertion of such a viewing aid, and larger
barrel-assemblies can have an angioscope and/or intravascular
ultrasouind probe built in to look out from the center of the
nose.
[4931] For placing stays, no more is necessary than a quick check
to confirm that the ductus wall is not so malacotic that
ductus-intramural implants must not be used. When quantitative
testing is necessary, as when the degree of sclerosis should
determine the force and speed with which stays are inserted; a
control syringe-configured stay insertion tool with built in
calibrated compression spring adjustment and testing device as
addressed above in the section entitled Stay Insertion Tools, can
be used. In contrast, control with a noncalibrated control
syringe-configured stay insertion tool is limited to the intuitive
reduction in speed of insertion that the operator can achieve by
not allowing the compression spring to expand according to its
intrinsic expansion (restorative, return) force.
[4932] The operator does this by slowly lifting his thumb to
moderate the speed with which the spring, hence, the thumb
plunger-rod with attached ejection blade, and thus the momentum of
insertion, is allowed to expand. Alternatively, to insert the stay
through and/or into harder, or sclerosed tissue, the operator can
remove his thumb, allowing the spring to snap back and insert the
stay at the momentum inherent in its expansion force. A stay
insertion tool can be produced to automatically adjust the thumb
plunger rod spring tension into the parameters of stay insertion;
however, the infrequent need for such a feature makes it cost
ineffective. The mechanical properties of the tissue to be treated
and the structures surrounding this tissue are primary
concerns.
[4933] Since compared to healthy tissue, the mechanical properties
of diseased tissue vary over a much wider range, a means for
testing the actual tissue considered for treatment in situ may be
imperative. For example, most vascular disease atherosclerotic,
degradation in elasticity of the arterial wall due to infiltration
by white blood cells that activate collagen and elastin-degrading
proteases, and the prognosis for this degradation to continue with
the administration of protease resistant medication (see, for
example, Nichols, T. C., Busby, W. H., Merricks, E., Sipos, J.,
Rowland, M., Sitko, K., and Clemmons, D. R. 2007. "Protease
Resistant IGFBP-4 Inhibits IGF-I Actions and Neointimal Expansion
in a Porcine Model of Neointimal Hyperplasia," Endocrinology
147(12):5634-5640, that does not interfere with the clearing of
fibrin, (see, for example, Sachs, B. D., Baillie, G. S., McCall, J.
R., Passino, M. A., and 13 other authors 2007. "p75 Neurotrophin
Receptor Regulates Tissue Fibrosis Through Inhibition of
Plasminogen Activation via a PDE4/cAMP/PKA Pathway," Journal of
Cell Biology 177(6):1119-1132) requires ascertaining whether the
arterial wall has retained sufficient strength to proceed with
implantation, and if so, with miniballs introduced using an airgun
or nonimpactively inserted stays introduced with a special
hand-tool, as addressed above in the section entitled Stay
Insertion Tools.
[4934] Due to variability in the mechanical properties of diseased
tissue from:
[4935] a. Condition to condition and in severity or stage of
advancement (see, for example, Maurice, R. L., Dandah, N., and
Tremblay, J. 2012. "Imaging-based Biomarkers: Characterization of
Post-Kawasaki Vasculitis in Infants and Hypertension Phenotype in
Rat Model," International Journal of Vascular Medicine at
http://www.hindawi.com/journals/ijvm/2012/364145; Cho, I. J., Shim,
C. Y., Yang, W. I., Kim, S. A., Chang, H. J., Jang, Y., Chung, N.,
and Ha, J. W. 2010. "Assessment of Mechanical Properties of Common
Carotid Artery in Takayasu's Arteritis Using Velocity Vector
Imaging," Circulation Journal 74(7):1465-1470; Cheung, Y. F.,
Brogan, P. A., Pilla, C. B., Dillon, M. J., and Redington, A. N.
2002. "Arterial Distensibility in Children and Teenagers: Normal
Evolution and the Effect of Childhood Vasculitis," Archives of
Disease in Childhood 87(4):348-351),
[4936] b. Age to age (see, for example, Maurice et al. 2012 Op
cit.; Majumdar, A. P., Jaszewski, R., and Dubick, M. A. 1997.
"Effect of Aging on the Gastrointestinal Tract and the Pancreas,"
Proceedings of the Society for Experimental Biology and Medicine
215(2):134-144);
[4937] c. Sex to sex (see, for example, Benetos, A., Waeber, B.,
Izzo, J., Mitchell, G., Resnick, L., Asmar, R., and Safar, M. 2002.
"Influence of Age, Risk Factors, and Cardiovascular and Renal
Disease on Arterial Stiffness: Clinical Applications," American
Journal of Hypertension 15(12):1101-1108);
[4938] d. Individual to individual (see, for example, Augst, A. D.,
Ariff, B., McG Thom, S. A., Xu, X. Y., and Hughes, A. D. 2007.
"Analysis of Complex Flow and the Relationship Between Blood
Pressure, Wall Shear Stress, and Intima-media Thickness in the
Human Carotid Artery," American Journal of Physiology. Heart and
Circulatory Physiology 293(2):H1031-H1037; Kornet, L., Lambregts,
J., Hoeks, A. P., and Reneman, R. S. 1998. "Differences in
Near-wall Shear Rate in the Carotid Artery within Subjects are
Associated with Different Intima-Media Thicknesses,"
Arteriosclerosis, Thrombosis, and Vascular Biology 18(12):
1877-1884);
[4939] e. Location to location (see, for example, Umale, S.,
Chatelin, S., Bourdet, N., Deck, C., Diana, M., and 4 others 2011.
"Experimental in Vitro Mechanical Characterization of Porcine
Glisson's Capsule and Hepatic Veins," Journal of Biomechanics
44(9):1678-1683; Egorov, V. I., Schastlivtsev, I. V., Prut, E. V.,
Baranov, A. O., and Turusov, R. A. 2002. "Mechanical Properties of
the Human Gastrointestinal Tract," Journal of Biomechanics
35(10):1417-1425; Tseders, E. E. and Purinya, B. A. 1975. "The
Mechanical Properties of Human Blood Vessels Relative to their
Location," Mechanics of Composite Materials 11(2):271-275; Kaski,
J. C. 2003. "Atheromatous Plaque Location and Arterial
Remodelling," European Heart Journal 24(4):291-293); and
[4940] f. Preceding or following an intervention (see, for example,
Giannattasio, C., Failla, M., Grappiolo, A., Bigoni, M., Carugo,
S., Denti, {acute over (M)}., and Mancia, G. 1998. "Effects of
Prolonged Immobilization of the Limb on Radial Artery Mechanical
Properties." Hypertension 32(3):584-587), a test that goes directly
to the actual tissue and equipment used is beneficial and often
essential to decide upon a course of treatment.
[4941] Since elevated protease levels are suspected to contribute
to the rupture of plaque leading to acute cardiovascular events
(Chen, J., Tung, C. H., Mahmood, U., Ntziachristos, V., Gyurko, R.,
Fishman, M. C., Huang, P. L., and Weissleder, R. 2002. "In Vivo
Imaging of Proteolytic Activity in Atherosclerosis," Circulation
105(23):2766-2771), at least when angioplasty and stenting are
elective, medication that moderates the action of proteases may
have been initiatied well beforehand. Whether or how to stent the
artery by the various methods described, whether medication would
allow a retention in elasticity, and so on, can determine whether
such treatment should proceed.
[4942] That plaque tends to become progressively calcified is
meaningful according to how much of it remains following the steps
taken to eliminate it. The resistance of the tissue to be treated
to puncture, perforation, and delamination can be critical for
success. Even with antithrombogenic medication administered,
punctures produce swelling that serves to provide spontaneous
self-sealing, and the inside of the stent-jacket may be wetted with
a topical coagulant such as Gelfoam.RTM., Gelfoam.RTM. with
thrombin, Oxycel.RTM., Surgicel.RTM., FloSeal.RTM., Avitene.RTM.,
bipolar cautery, or argon beam coagulation to assist in sealing a
puncture.
[4943] Nevertheless, a puncture will be associated with an errant
discharge that could injure surrounding structures, possibly damage
nerves, and is to be prevented. In testing, a continuous rod sees
the expulsive force at its proximal end and directly transmits that
force to the tissue at the distal end. There is little transmission
loss in velocity, hence force of impact. By contrast, the miniballs
are more subject to losses in momentum due to any differences in
the bends and rolling resistance of the barrel-assembly that
distinguish the conditions of the test from those of actual
use.
[4944] Provided the test is conducted under the same conditions of
barrel-assembly bends and length as in the actual use for which the
test is conducted, this can be compensated for by taking the test
result as proportional For this reason, it is essential that the
test be conducted under the conditions of bending of the
barrel-assembly to apply in actual use. In situations where the
consequences of a puncture are less important than procedural
speed, a preliminary discharge of a single miniball at the affected
tissue with the force presumed necessary is performed, the result
evaluated, and the appropriate adjustment made.
[4945] Otherwise, no discharge of miniballs into diseased tissue
should precede puncture strength testing. While intraoperative time
constraints may preclude pretesting for each individual miniball to
be implanted, the puncture strength of the specific lesioned tissue
in the specific patient should be determined. This value is
ascertained by reproducing as closely as possible the effect of a
miniball on the tissue to be implanted, and in this way, obtaining
information reliable as may be had concerning its penetrability and
puncture resistance. The longitudinal and radial strength of the
lumen wall and its resistance to separate intra- or inter-laminarly
(tunically delaminate) central in determining the applicability of
the means described herein, a malacotic condition of the outer
layer or layers of any type ductus will present multiple symptoms
and seldom go undiagnosed.
[4946] The limitation of such a condition to the outer layers is
not an aspect of the recognized vasculitides (see, for example,
www.nhlbi.nih.gov/.../Diseases/vas/vas_all.html), and a test for
wall strength is provided in the section below entitled In Situ
Test on Endoluminal Approach for Susceptibility of the Ductus Wall
to Puncture, Penetration, and Perforation. Since testing is
prescribed for aeroballistic implantation regardless of whether the
implant will then be subjected to magnetic traction, a deviant
condition could escape detection only when the test is not
performed or is performed on tissue that is in transition, or at
test points that are too distant from and thus not representative
of the tissue actually to be implanted.
[4947] Diseased tissue is more variable than healthy tissue in its
mechanical properties, and is additionally capable or becoming
alterred as the result of having undergone an angioplasty or an
atherectomy. The test is intended to determine whether the ductus
wall is of sufficient strength to be implantable with either
miniballs or stays, and if so, the depth necessary to avoid
pull-through; or the gradual pulling through of the implant
radially outwards until it perforates through the adventitia under
magnetic traction.
[4948] As will be described, to reduce the risk of pull-through,
miniballs of any kind can be deep surface textured and coated with
a tissue adhesive-hardener; usually a cyanoacrylate tissue cement
to gain the advantage of quick initial set. So that adhesion
persists after the adhesive has broken down, the adhesive used
should break down in pace with the ingrowth of surrounding tissue
into the undercut furrows at the surface. However, because the
strength of tissue in transition may weaken, the efficacy of such
means is contingent upon the sufficiency of the prognosis.
Generally, preinsertion testing is extraluminal to place stays and
endoluminal to place miniballs.
[4949] Preinsertion testing for ductus-intramural implants checks
for tissue strength, whereas postprocedural or followup diagnosis
checks for dislodgement, infection, and notwithstanding the fact
that nonallergenic materials are used throughout, an unanticipated
or idiopathic tissue response. Where postprocedural symptoms have
appeared, testing treatment with either miniballs or stays might be
endoluminal or extraluminal. The numerous considerations involved
properly place patient inconvenience and imposition high on the
list; absent symptoms, postprocedural diagnostics should be limited
to noninvasive imaging.
[4950] XVII2. Midprocedural Preinsertion Testing
[4951] For endoluminal approach, imaging methods that provide an
indication as to the strength of the wall surrounding the lumen has
significant value. For the placement of stays and miniballs, the
primary concern is tissue hardness, which is inseparable from
penetrability and elasticity. Unless extreme, lumen wall distention
for proper matching with a stent-jacket of suitable resilience or
an impasse-jacket with suitable closing spring force can usually be
dispensed with, as can testing before placing wide stays coated
with cyanoacrylate cement.
[4952] Midprocedural testing is by the simplest and quickest means
available, the use of intravascular ultrasound, for example,
reserved for endoluminal approach, and preferably, where a fine
probe can be passed down the central channel of a combination-form
barrel-assembly. For the purpose of stenting, stays are
substantially less susceptible to pathological alteration in tissue
strength than are miniballs, so that no more than a quick probing
to rule out an area of extreme malacosis is necessary.
[4953] Methods for gauging the mechanical properties of ductus
walls in situ (see, for example, Restrepo, M. B. 2010. Ultrasound
Study of the Mechanical Properties of the Arterial Wall, Doctoral
Dissertation, Mayo Medical School, Rochester, Minn.; Glozman, T.
and Azhari, H. 2010. "A Method for Characterization of Tissue
Elastic Properties Combining Ultrasonic Computed Tomography with
Elastography," Journal of Ultrasound in Medicine 29(3):387-398;
Williams, M. J., Stewart, R. A., Low, C. J., and Wilkins, G. T.
1999. "Assessment of the Mechanical Properties of Coronary Arteries
Using Intravascular Ultrasound: An In vivo Study," International
Journal of Cardiac Imaging 15(4):287-294) are suitable for
obtaining less point-specific lumen-circumferential mechanical
information concerning the condition to be treated, and the time
and cost therefor can usually be avoided.
[4954] In a procedure that requires endoluminal entry, information
obtained with intravascular ultrasound may be valuable as
background to immediate mechanical information concerning the point
to be implanted. However, the probe is preferably not inserted
before and after insertion of the barrel-assembly, but rather at
once by insertion through the central channel of a combination-form
barrel-assembly or as built into a small gauge radial discharge
barrel-assembly. To achieve predictive value, the test must be
directly performed on the tissue to be implanted, or if testing
would prove damaging to that tissue, then adjacent tissue in what
appears with confidence to be in the same condition.
[4955] The test also must be performed in a manner that allows the
quantitative readings to be translated into equivalent settings for
adjustment in the discharge velocity of miniballs or the spring
tension in a control syringe-configured stay insertion tool with
calibrated thumb-rod return spring screw adjustment. As addressed
above in the section entitled Stay Insertion Tools, such a stay
insertion tool uses its ejection blade with protective cap as a
test probe to obtain readings directly applicable to adjustment in
the spring tension, which function can be controlled by an inmate
microcontroller. An intricate and expensive tool of this kind is,
however, justified only for use with pathology that presents
frequent and significant distinctions in mechanical properties from
one small segment or area to the next.
[4956] Exactitude in the force of stay insertion rarely critical,
the nonquantified or intuitive force of penetration applied by the
operator is almost always satisfactory. A primary advantage in the
use of wider stays, especially when coated with a quick setting
tissue cement, is precisely that testing can often be dispensed
with, reducing procedural time. The equivalency sought through
quick checks includes that between the resistance to penetration
reading and the setting of the exit velocity for miniball
discharge, which requires that separate tables be prepared for
miniballs of different diameter and mass. The readings are
preferably obtained with a special mechanical microprobe force
gauge service catheter passed down a service channel and thus
following the same path as would a miniball.
[4957] The microprobe service catheter registers force and
indentation in a manner similar to a auto tire pressure gauge in
that the expelled length of the gauge is calibrated. To distinguish
between surface hardness as indicated by indentation and ductus
wall or organ cortex or capsule elasticity, for example, requires
direct viewability. This does not, however, equate to a need for
high cost imaging but rather use of an attached or incorporated
angioscope. Alternatively, a resistance force measuring strain
gauge tipped microprobe can be used. If ensheathed within a
spring-loaded and calibrated outer tube, this can also furnish
indentation and elasticity data.
[4958] Quantitative findings found with a mechanical microprobe,
for example, which registers force indentation for the force
indicated, are referred to a table of indentation and
deflection-equivalent exit velocities for the type miniball used.
Apart from apparatus-related factors, due to the shock impact and
velocity of penetration of a miniball, the response characteristics
of the tissue tested will differ from the values obtained with a
manually projected probe such that accurate and dependable
equivalency is not achieved; however, such testing is not to obtain
equivalency of scientific exactitude but only a quantification
sufficient for the immediate practical purpose. When the results of
testing ndicate a malacotic condition so that a perforation might
occur even with the setting low, the use of stays is indicated.
[4959] If limited to a small segment not to be skipped or
straddled, stays are used in that segment. Alternatively, when
procedural time is to be kept to a minimum and the exceptional
segment is small, a shield or double-wedge jacket can be placed
about the malacotic segment and discharge continued without
interruption, the interjection, or folowup placement of stays in
the deviant segment. Unless hemostasis has been impeded through
administration of a potent platelet blockade or antiaggregate such
as abciximab within the preceding 12 hours (see, for example,
Emmer, J. H. Jr. 2000. "Clinical Experience in Coronary Bypass
Surgery for Abciximab-treated Patients," Annals of Thoracic Surgery
70(2 Supplement):S33-S37), a little more than pinhole-sized
perforation produced by a miniball will spontaneously seal
quickly.
[4960] Alternative methods can, however, play a supplementary role
in assessing tissue. While suitable for diagnosing the disease, for
followup examination, and alerting to trouble spots, neither
testing methods that employ extracorporeal or intravascular imaging
provide the level of practical and immediate mechanical information
needed. The conditions indicated necessitate spot-testing--testing
that is simple, empirical, and quick, with the use of imaging
equipment invoked only when necessary. Testing for ballistic
implantation is for susceptibility to perforation, delamination,
and pull-through, whereas stays, especially when more expansive and
coated with tissue cement when inserted, are not susceptible to
perforation and are less susceptible than are miniballs to
pull-through or delamination.
[4961] Routine diagnostic testing of ductus wall segments would
best be nonintravascular; but here, the disease has been diagnosed,
testing is to ascertain the response of the tissue not in general
terms but rather in terms of the methods for implant infixion
described herein, and the need for invasive therapy has been
determined, much depleting noninvasiveness of the value it normally
has. Certain delimited areas proposed for implantation may lie
adjacent to a ganglion, node, or other structure that could incur
injury were testing to result in an accidental strike or an
unexpected perforation. When a particular spot proposed for
implantation is not to be tested, nearby tissue in what appears to
be the same condition but outside the area for such a consequence
is tested.
[4962] Any preliminary treatment affecting the mechanical
properties of the tissue must be included in the test. Testing
minimizes the need for empirical `inching` or `edging` up to the
most effective exit velocity, which process is less safe,
time-consuming, and is not usable where the tissue to be treated is
too small in area to allow such a maybe right, maybe not approach.
Materials testing of luminal wall strength in the laboratory is
relatively well established (see, for example, Sommer, G. 2010.
Mechanical Properties of Healthy and Diseased Human Arteries:
Insights into Human Arterial Biomechanics and Related Material
Modeling, Graz, Austria: Verlag der Technische Universitat Graz)
but not applicable to in vivo testing.
[4963] XVII3. Confirmation of Terminus
[4964] Whether due to irregularities in hardness of the ductus
wall, weak adhesion among its tunics, or improper adjustment of the
exit velocity, a miniball over- or under-shot, that is, falls short
or overextends the end of trajectory intended, can be
nonfunctional. Medicinal miniballs seldom require more than close
approximation to the target tissue. Stenting miniballs, however,
must not fall short or overextend the segment to be subtended by
the stent-jacket. The trajectory terminus is quickly discerned by
passing a fine catheteric magnetometer probe through the access
incision and along the adventitia.
[4965] Provided the muzzle-head has just been degaussed, such a
sensor can be passed down an unused barrel-tube as service-channel
and the muzzle-head passed over the length of the ductus to the
maximum distance that the miniball might have penetrated. This is
usually not justification for a preliminary test discharge for
effect but rather following the first discharge at any target point
that might deviate in hardness from the tissue surrounding it to a
degree more than negligible. For ballistic implantation, tissue
hardness, or resistance to penetration, is the principal factor.
The sudden shock delivery of ballistic infixion allows elasticity
to be disregarded.
[4966] A catheteric magnetometer probe can reveal ductus-intramural
implant positioning either by extraluminal approach by insertion
through the access incision at the body surface or by endoluminal
approach by passage through an unused barrel-tube as
service-channel Sudden displacement as overcomes elasticity but can
result in an improper end of trajectory is achieved not only by
ballistic infixion, but by the sudden release of the thumb ring of
a control syringe-configured stay nsertion tool, and the abrupt
attraction of a miniball by a powerful extracorporeal
electromagnet, which pulsed, however, allows sufficient control
over miniball repositioning. While a nonadjustable control
syringe-configured stay insertion tool allows the operator to
gradually raise his thumb, reducing the force and speed of stay
insertion, such use of the tool while almost always dependable, is
intuitive.
[4967] If the operator removes his thumb from the thumb-ring, the
ejection blade will deliver the stay with the force and speed set
by the thumb plunger-rod return spring. This property is built
into, inherent in the tool, and unadjustable. By contrast, an
adjustable control syringe-configured stay insertion tool allows
the force and speed of stay insertion on sudden release to be
adjusted. This is of some advantage when a long sequence of stays
must be placed in the least amount of time and/or an inadvertent
release of the thumb-ring could result in the intravasation or the
tearing of a stay through the adventitia, possibly perforating into
another structure.
[4968] Using ballistic infixion, the operator or an assistant uses
a graph or table that translates tissue hardness for various
tissues in various states of disease into the equivalent miniball
discharge exit velocity or force of impact for use with miniballs
of given diameter and mass. The exit velocity can be quickly
checked by test discharge against a pressure registration paper
such as Pressurex.RTM.. An equivalent graph or table for converting
the tissue properties into the setting for an adjustable stay
insertion tool is provided with the tool.
[4969] XVII4. In Situ Test on Endoluminal Approach for
Susceptibility of the Ductus Wall to Puncture, Penetration, and
Perforation
[4970] These susceptibilities are automatically revealed and
quantified when the force gauge or strain gauge-tipped catheter
probe used to test tissue hardness and elasticity punctures,
penetrates, or causes a through and through perforation of the
ductus wall or organ capsule. These probes can be passed down an
unused barrel-tube as service-channel or attached alongside the
stay insertion tool. Provided time allows, these consequences are
avoidable by avoiding endoluminal approach and instead placing wide
cyanoacrylate cement-coated stays. Endoluminal approach denotes the
use of a barrel-assembly, which is transluminal (through the lumen
to be treated), as opposed to the use of a stay insertion tool,
which inserts stay type ductus-intramural implants from outside the
ductus, characterized as an extraluminal approach.
[4971] Atheromatous lesions are not simply unique due to these
variables but may be intrinsically lesion-specific (see, for
example, Kaski, J. C. 2003. "Atheromatous Plaque Location and
Arterial Remodelling," European Heart Journal 24(4):291-293). A
preliminary extracorporeal method that involves first consulting a
table for the probable range of exit velocity and impact force data
for the barrel-assembly and miniballs to be used for the type and
the condition of the tissue to be treated can provide no more than
a reasonable approximation for initially setting the airgun exit
velocity, the airgun then test discharged against a ballistic
pendulum or against impact force registration paper as described
above in the section entitled Control of Propulsive Force or Exit
Velocity by Means of a Calibrated Slide Cover over a Slot Cut into
the Valve Body.
[4972] The pretest provided is based on the principle that the
momentum out is equal to the momentum in less friction, where
friction is reduced to the point that for a practical spot check,
it may be disregarded. Without a means for pretesting the lumen
wall by the means specified, literal testing would require actually
discharging for effect a miniball such as one of like diameter made
of sugar with superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder to match the mass of the
miniballs to be used.
[4973] An indication as to the strength of the lumen wall is also
essential when the use of an external hand-held electromagnet and
the field strength that may be applied to pull the muzzle-head in a
preferred direction with this aid must be assessed lest an impact
by the muzzle-head tear or tear through the wall. For preempting
miniball perforations or a weakening of the lumen wall by high
density implantation as might result in an aneurysmal failure of
the wall, the results of such a test can also indicate the need to
position the stent-jacket prior to initiating ballistic
implantation. Another use for such a test is in order to evaluate
whether the ductus is so malacotic that a graft is required, or if
not so weakened, whether stays of wider than usual facing area can
be used.
[4974] Because this area can be considerably greater than that of a
miniball, the use of stays may make the application of an
extraluminal stent possible where miniballs could not. Unless a
preparatory angioplasty is felt essential, stays can also be used
to eliminate any transluminal procedure, both stays and
stent-jacket being introducible through the same one or two small
incisions. When the disease process is progressively malacotic so
that the immediate result given by a lumen wall strength test would
likely become invalid soon, the transluminal methods described
herein, to include pretesting, ballistic implantation, and the use
of an external magnet to pull the muzzle-head in a preferred
direction should be discounted and a graft, the use of conventional
endoluminal methods, or of large surface area stays for resisting
pull-through considered.
[4975] This allows the hardness of the lumen wall, which disease
changes, to be evaluated quickly (empirically) without a need for
calibration, computation, or conversion. While quantitative
findings would appear to be more dependable, not every point along
the lumen wall to be implanted can be tested, and the hardness of
diseased tissue is subject to wide variability that actually makes
confidence in findings obtained from a different point ill-advised.
Furthermore, by actually employing the discharge mechanism, the
reading obtained from a force measuring gauge, mechanical force
tester, or mechanical puncture tester need not be translated into
the corresponding exit velocity opening the way for human
error.
[4976] The test is devised for simple, direct, and immediate
results on an empirical and qualitative basis for practical use and
makes no pretence to a level of precision required in the
laboratory. To be described now is an empirical or purely
observational means for quickly testing the penetrability and
puncture strength of tissue in situ with any kind of airgun,
regardless of the kind of clip used to load the airgun. Provided
the operator initiates testing with exit velocities too slight to
cause injury, increases the initial velocity slightly for each
successive discharge, and avoids repeated testing at precisely the
same spot, test discharge or discharge for effect, because it is
empirical, that is, uses the actual tissue to be implanted and the
actual apparatus to effect implantation, can afford dependable
results quickly.
[4977] Testing is never conducted other than immediately preceding
actual discharge under precisely the set of physical conditions and
depth of general anesthetization and any other medication to apply,
and the projectile used for testing is different only to the extent
essential to prevent its unrestrained projection beyond the
muzzle-head. Where differences in tonus, pulse, or peristalsis
sufficient to affect the test are possible, the operator should
wait for the same moment in the action cycle to discharge the
airgun. While significant nonuniformities in the thickness, degree
of calcification, and so on, of the diseased tissue warrant
retesting before resumption, rather than to unduly detain
completion of the procedure, lesions of a kind are assumed to have
the same penetration resistance.
[4978] To preclude flexion, a surrogate projectile limited in
forward displaceability having a length equal to that of the
chamber plus that of the barrel-tube is made of a solid rod or
closed ended thick walled tube of self-bondable E.I. Dupont de
Nemours Teflon NXT.RTM. polytetrafluoroethylene that matches in
caliber or diameter the miniballs used with the barrel-tube. Using
a tube, a miniball of the same diameter is bonded onto the front
end of the tube by means of an adhesve such as surgical
cyanoacrylate cement. Using a solid rod, the front end of the rod
is shaped into a hemisphere to simulate a miniball, with
radiopacity achieved by plating or capping the tip, first etching
the interior of the cap with, for example, Acton Technologies,
Inc., FluoroEtch.RTM. or W.L. Gore.RTM. and Associates, Inc.
TetraEtch.RTM. or blown-ion air plasma type corona, or flame
surface treated, then bonding the cap onto the front of the rod
with an adhesive such as Loctite Hysol Cool Melt.RTM..
[4979] Whereas the leading end is shaped like the miniball for
penetrative effect, the back end is likewise to react similarly to
the propulsive gas. Since the miniball is massive if tiny
(typically 0.4 millimeters), the test rod or tube of plastic, such
as polytetrafluoroethylene to minimize friction, can be made to
substantially the same mass. The rod or tube can be inserted into
the proximal end of the barrel-assembly when disconnected from the
airgun, removal from and replacement in the airgun barrel of the
barrel-assembly as needed accomplished quickly. The test rod or
tube must be sufficiently pliant to pass entirely through the
barrel-assembly without exerting any straightening effect as would
distort the result, and should not interfere with rotation of the
turret-motor.
[4980] The testing rod or tube has a dorsal extension, a tab or
key, toward its rear or proximal end within the chamber and is
provided with a depth gauge type calibration over its distal
segment. The key is made by inserting and bonding a tab of
polytetrafluoroethylene that is pliant at the base of its faces
into a slot cut into the rod or tube. The adhesive used to bond a
cap at the front end and key toward the rear is Loctite Hysol Cool
Melt.RTM.. The key has rounded and polished edges and fits into or
engages a slot or groove milled or routed into the ceiling which
begins at the distal end of the chamber so that the key can be
inserted into and slid along the groove with no more than the
intermittent and slight friction of aligning contact.
[4981] In a specially constructed interventional airgun intended to
achieve deeper penetration, the ceiling groove must be longer and
may extend past the front of the chamber into the barrel. The
groove and key are made narrow as not to affect discharge. With a
break-breech airgun, the test rod or tube is inserted into the
barrel from the rear leaving enough length to insert the pliant key
or tab toward into the slot or slideway in the valve body. The
testing rod is pushed back into the chamber and the breech closed
so that the front of the testing rod or tube is flush with the
muzzle-port. Accordingly, the testing rod is inserted in the
barrel-assembly prior to initial insertion into the vessel or duct
to be treated.
[4982] Thereafter, the testing rod can be freely removed or
reintroduced whenever the target diseased tissue appears different
in penetrability. When the design of the gun is such that the rear
of the test barrel is inaccessible, the testing rod is inserted
through the muzzle, then twisted until the key engages the
slideway. The ends or lands of the groove, typically on the order
of two millimeters apart, thus represent stops that establish the
limits of forward and backward movement or throw of the testing
tube or rod and therewith the distance that the tube or rod can
protrude out of the front end opening of the barrel-tube, or
muzzle-port.
[4983] When a motorized muzzle-head is to be used to rotate or
torque the muzzle-head, the barrel-tubes will have a rotary curve
superimposed upon or compounded with the curve that directs these
from the axis to the outer edge. The rotary curve compounded with
the splay curve poses additional rolling resistance for the
miniballs, so that testing should also be conducted with the
muzzle-head rotated to angles to be used in the procedure. In use,
a table provided with the factory-calibrated airgun is consulted
for the optimal impact force and range of impact force settings
that proved optimal for such diseased tissue at immediate autopsy,
to include those at various rotary positions of the
muzzle-head.
[4984] Since the settings are determined by the maker for the
specific model airgun by comparison of its discharge at each
setting to the impact force values obtained with the aid of a
ballistic pendulum at autopsy, no compensation for barrel-tubes of
higher friction is needed. Normally, the force imparted to the
testing rod or tube is transferred with insignificant loss to the
diseased tissue to be tested. However, when, for example, entry is
inguinal and the target coronary, the barrel-assembly and testing
rod follow a long and tortuous path that can dissipate a proportion
of the momentum sufficient to invalidate the impact upon the target
tissue as a basis for setting the controls on the airgun.
[4985] Such nonuniform resistance to projection of the testing rod
or tube compared to a miniball are reflected in proportionally
higher control settings specified in the table provided by the
manufacturer. If the most common value in the range specified by
the table results in puncture of the tunica adventitia, then the
operator goes to the lowest value in the range. If the lowest value
in the range still punctures through the adventitia, then the
operator goes to the lowest value of the airgun. The results of the
test discharge are carefully noted, and as few as possible
adjustments made until the depth sought is attained. The proper
value for the instant diseased tissue is arrived at in this
strictly observational manner, preliminary value gathering,
quantification, and computation accomplished by the maker, so that
testing conducted mid-procedure is always strictly observational or
empirical and takes the least time.
[4986] The use of tethered miniballs as testing devices is
discounted as usable only over short distances along straight
paths. Contacting the internal wall of the barrel-tube, which is
unavoidable in a curve, tethered miniballs suddenly roll, begin to
wrap their tether around them, which clogs and rubs against the
barrel wall, abruptly and unpredictably yanking and braking the
miniball. Such action unpredictably and unreproducibly consumes
miniball momentum, completely invalidating the results of testing
by such means. The testing method and apparatus described
constitute a means of durometer testing living tissues whether
normal or diseased in situ.
[4987] XVII5. In Situ Test on Endoluminal Approach for Intra- or
Inter-Laminar Separation (Delamination, Laminar Avulsion)
[4988] Midprocedural susceptibility to tunical or intratunical
delamination and postprocedural confirmation of delamination can
both be ascertained with the aid of intravascular ultrasound. In
the vascular tree, both pertain to the use of ductus-intramural
implants in extraluminal stent-jackets, not those used to implant
medication and not subject to an outward radial force. In the
gastrointestinal tract, the more complex and forceful action of the
muscle within the ductus wall means that the wall will be strong
when normal, but recommends susceptibility testing in disease.
[4989] Preinsertion susceptibility in the vascular tree is checked
by inserting a fine aspiration line through the access incision at
the body surface and applying a vacuum equal in tractive force to
that to be exerted by the stent-jacket; delamination is overcome by
injecting a quickly setting tissue binder-hardener and retesting.
Even if only a small portion of the segment to be stented is
initially susceptible, a stent-jacket of maximum flexibility is
placed. This may disallow the use of intrinsically and
quasi-intrinsically magnetized stent-jackets. In health, the layers
or tunics in the wall of a ductus cohere by gradual transition from
the tissue type of each to that of the other at their interface
despite tonic, pulsatile, or peristaltic contraction and relaxation
of the smooth muscle at the center of the wall and the orthogonal
shear generated by the travel of this action along the wall.
[4990] In disease, this cohesion may become weakened or undone.
Atheromatous plaque, for example, separates the intima from the
media. Therapeutic measures such as balloons and lasers can also
affect this cohesion. In stenosed or constricted conditions where
outward retraction of the outer layer or layers relieves the inward
stenosing force that originates in these so that the force of the
fluid within is then able to restore substantial patency,
delamination, whether preexistent or caused by the vascular
endomural implants may not matter. Since the ductus-intramural
implants to serve as the intraductal component of a magnetic stent
are preferably situated between the outer tunics of the ductus, for
these to be pulled apart by the implant or to have been pulled
apart by disease would result in the outer layers being held to the
stent-jacket with the periluminal layer little if at all
affected.
[4991] Because this would nullify the patenting effect intended,
extraordinary measures are taken to avoid this eventuality, to
include the coating of implants with various tissue strengthening
and binding agents. The repair of delamination (laminar avulsion)
warrants close study. The tests to be described must all be
performed at the site and time of implantation. That is, unless the
ductus is in the condition it will be when implanted, test results
are of no value. Thus, for example, the application of an agent to
cause the ductus wall to swell for ease in the insertion of stays
will alter the properties of the wall, invalidating any test
results that would have been obtained prior to having caused the
ductus wall to swell.
[4992] Because the placing of implants, whether stays or miniballs,
will inherently separate the radially outward from the inward
layers in immediate contact with each implant, as well as to
minimize testing time, both the endoluminal and extraluminal
approach tests, which should be performed prior to the use of
miniballs or stays respectively, should be performed after an
implant coated with a solid protein solder has been placed and kept
warm long enough to achieve a strength of bonding sufficient to
resist separation under the magnetic traction exerted by the
stent-jacket. This interval can be determined empirically by
applying the stent-jacket of the lowest field strength that will
open the lumen at intervals following implantation of the test
implant.
[4993] If the interval for curing sufficient to withstand the
stent-jacket exceeds that over which the ductus access wound should
be kept from knitting, then the use of stays is discouraged as
requiring reincision at or beside the original access incision.
Unless contraindicated for reasons of tissue compatibility, testing
should always use implants with a coating of a tissue
adhesive-hardener from the outset. The time for denaturing and
reaching initial set of a solid tissue adhesive-hardener if used is
allowed and the prospective stent-jacket tentatively positioned to
observe whether magnetic traction imposes a degree of intraparietal
separation that is too pronouced for the adhesive-hardener to
support.
[4994] With a ductus such as an artery, which is always filled and
thus subject to outward, or centrifugal, force, a snug (not tight)
stent-jacket will often reduce a separation without the need for an
adhesive. The distinction in degree is something the test should
reveal. One advantage in ballistic insertion is that sudden impact
and momentum can conceal inconsistencies or nonuniformities in the
target tissue that would redirect a miniball delivered at a lower
but still functional velocity. When such an nonuniformity consists
of an interface between layers in the wall of the ductus such that
unless a stent-jacket were placed prior to initiating discharge the
miniball would lift the outer layers leaving the inner layers
unaffected, the results of the preceding test will conceal this
fact necessitating another test performed at a low velocity in
order to uncover such a condition.
[4995] Wide stays coated with cyanoacrylate cement should prevent
delamination. If felt necessary, multigate color Doppler imaging
(see, for example, Mitchell, D. G. 1990. "Color Doppler Imaging:
Principles, Limitations, and Artifacts," Radiology 177(1):1-10) is
used to view the ductus while an aspiration line inserted through
the access incision is used to draw the adventitia outward. A
sudden abaxial displacement of the adventitia is indicative of
tunical or intertunical delamination. The ductus must withstand
forces imposed by the sum of hemodynamic and magnetic retractive
forces. Testing at lower velocities also gives a much better if
time-limited indication as to the propensity for pull-through where
the preceding test will report pull-through only as instantaneous,
that is, as a perforation.
[4996] Accordingly, whether endo- or extraluminally, testing for
intraparietal separation or delamination (laminar avulsion) should
be performed before the preceding test for perforation and
puncture. Whereas this endoluminal test is suitable for miniballs,
the test next to be described, which is performed from the outside
of the ductus, is suitable for stays, which then allow the lumen to
be avoided both in preliminary testing and implantation. Neither
test for intraparietal separation performed at high speed,
conversion data sufficient to allow eliminating the need to perform
the extraluminal test for separation next to be described when the
endoluminal test described here had already been performed can be
provided.
[4997] When the luminal constriction is attributable to an inner
(adluminal) tunic or layer, however, unless extraluminal implants
can be placed to undercut and lift this inner layer, delamination
is likely to result in the insinuation and continued travel of
miniballs between the parted layers or a useless retraction of the
outer layers under the constant if mild tractive force exerted by
the transversely magnetized metallic jacket or similarly magnetized
bar magnets mounted about the outer surface of the base-tube that
would leave the diameter of the lumen unaffected.
[4998] Depending upon the specifics of the condition then, it may
be best to obtain an indication as to the cohesion of the layers in
the luminal wall. To empirically check the tunic and laminae for
susceptibility to delamination from within the lumen, an adhesive
delivery-capable testing catheter of the same diameter as the
miniballs for insertion, typically 0.4 millimeters, with
hemispherical tip at the front and exceeding the barrel-tube length
by two to five millimeters is passed through the barrel-tube that
is closest to the lumen wall on the side to be implanted.
[4999] Such a test serves to determine whether a. A tissue
adhesive-hardener is needed, b. To use miniballs or stays, and c.
If miniballs, whether to place the stent-jacket prior to initiating
discharge. The hollow test rod can be used to inject a commercially
available radiopaque solution that will then fill the void in any
separation between layers. While kept under view tomographically,
the test rod or adhesive delivery-capable catheter is slowly forced
through the intima and media to the adventitia-media interface.
[5000] Continued force then reveals whether the adventitia will
separate from the subjacent media under the force that would be
exerted by a stent-jacket that would exert the minimum tractive
force essential to make the ductus patent. In situations where an
accidental perforation would not spontaneously seal itself promptly
and it is not desired to access the exterior of the ductus through
a keyhole incision, preferably the original, but alternatively
another test catheter having a lumen through which a long-chain
methacrylate tissue cement can be injected is used.
[5001] XVII6. Endoluminal Approach Test for Intra- or Inter-Laminar
Separation Following the Insertion of a Test Miniball
[5002] The use of a fine catheteric aspiration line is addressed
above in this section. This test pertains when the ductus wall will
be subjected to a radially outward retractive force no greater than
the encircling stent-jacket must exert to maintain the ductus in a
patent state. Since to place the stent-jacket in encircling
relation to the ductus requires entry through a small incision at
the body surface, the test requires no additional invasive entry.
For this reason, the test is the same as that for extraluminal
approach as addressed in the section that follows.
[5003] XVIII. In Situ Test on Extraluminal Approach for Intra- or
Inter-Laminar Separation (Delamination, Avulsion)
[5004] As stated in the preceding section entitled In Situ Test
upon Endoluminal Approach for Intra- or Inter-laminar Separation
(Delamination, Laminar Avulsion) delamination is of concern when
the stenotic condition is attributable to an inner layer that
cannot be undercut for outward retraction so that to draw the outer
layers outward would have no effect on the diameter of the lumen.
When the exterior of the ductus can be accessed through a keyhole
incision, a commercially available radiopaque solution is injected
into the lumen wall with a very fine hypodermic needle.
[5005] The ensuing pattern should allow a disproportionate lateral
spreading through and characteristic of a separation between the
layers in the wall of the ductus to be distinguished from entry and
flow with other contents through the lumen. Even if an accidental
injury or open surgery has fully exposed the ductus, to reliably
evaluate any delamination between its layers using only a forceps
or probe and without transecting it is impossible, making the need
for contrast clear. Ideally, conversion data are provided to allow
eliminating a need to perform the endoluminal test for separation
described in the preceding section when the this endoluminal test
had already been performed.
[5006] A simple method for evaluating susceptibility to
delamination is addressed above in this section. The procedure call
for passing a fine catheteric aspiration line connected to a
precision vacuum gauge through the access incision at the body
surface to apply a retractive force not significantly greater than
that to be exerted by the stent-jacket. An assessment as to the
outward radial tractive force that the wall can withstand is
obtained by engaging the adventitia to the least depth possible
with a miniature skin hook connected to a small precision or
laboratory grade digital force gauge or high quality hand scale,
such as one strain gauge based.
[5007] The pattern of infiltration between layers of the injected
fluid and the pulling force on the scale indicate the magnetic
traction that would be withstood prior to applying a tissue
adhesive-hardener to the stays interventional measures delineated
under the section above entitled Miniballs and Stays Coated with a
Heat-activated (-melted, -denatured) Tissue Adhesive-Hardener. The
acquisition of data as to the range of tolerance for force of
magnetic retraction without and with impregnation of the
intraparietal connective tissue with a tissue adhesive-hardener in
which the implants are likewise disposed or embedded so that the
implanta and surrounding tissue are effectively bonded together may
be expected to accumulate.
[5008] XVII8. In Situ Test on Endoluminal Approach for Intra- or
Inter-Laminar Separation Following the Insertion of a Test
Miniball
[5009] Delamination warrants testing only when the ductus will be
subjected to the encircling retractive force of a stent-jacket, not
when the miniballs or stays are medicinal, consist of other
therapeutic substances, and/or radionuclides where no jacket is
placed. The use of a fine aspiration line on extraluminal approach
is addressed above in this section. If extraluminal access would
impose no additional trauma, then that route is preferable for
ascertaining whether a ductus-intramural implant has migrated
indicating a delamination.
[5010] Delamination on endoluminal approach may occur if the
stent-jacket had been prepositioned, in which case the jacket will
block approach from outside, so that testing must be endoluminal.
If the barrel-assembly does not incorporate an intravascular
ultrasound probe or an angioscope and is a combination-form
barrel-assembly as would allow such a probe to be inserted through
the central channel to the nose, then to view whether the miniball
is displaced requires extracorporeal imaging.
[5011] Later during the same procedure, after an interval not less
than that for a coating of cement or protein solder if used to set,
the muzzle-head is moved to a position at a longitudinal distance
from the usually miniball or stay, which should be tantalum
contrast coated. The recovery electromagnet to that side is
energized, and the implant viewed to see whether it is displaced.
If the electromagnets are not marked as to that to one side and
that to the other, then the rotational angle is obtained from the
machine controller, which in an ablation or angioplasty-capable
barrel-assembly will be the inmate microcontroller. This will
indicate which magnet is closest to the site.
[5012] XVII9. In Situ Test on Extraluminal Approach for Resistance
to Centrifugal Pull-Through.
[5013] Wide cyanoacrylate coated stays pose no risk of pull-through
as would warrant testing. If a stent- or shield-jacket is
prepositioned blocking access through the incision through which it
was inserted, then tissue that returns the same test results is
used for testing. To target the test miniball and not affect nearby
implants, the fine probe of an extracorporeal electromagnet is used
to extract the same kind of miniball as a test miniball out through
the adventitia.
[5014] If the force of attraction at which pull-through occurs is
not significantly greater than that to be exerted by the
stent-jacket, then miniballs with protein solder are used and
heated to flow the solder into the surrounding tissue. Miniballs
with a surface that is textured and undercut for tissue ingrowth to
replace the solder over the time the solder breaks down is
addressed in numerous sections above. Also addressed is the use of
injection hypotube tipped catheters as service-catheters and
injection tool-inserts to inject cyanoacrylate cement to flow about
the miniball.
[5015] XVII10. Interconvertibility of Results Among Tests
[5016] The use of a combination mechanical force and magnetometer
probe is addressed above in this section. Tools that inherently
provide force readings convertible between mechanical, magnetic,
and air moving push (exhaust, blowing) and pull (vacuum) forces
expedite and generalize the interpretation of measurements as among
these forces. To the extent that the endoluminal test for
perforation and penetration and that for intraparietal separation
duplicate steps, these steps ought not require to be repeated.
[5017] Furthermore, since one finding that either the endoluminal
or extraluminal approach test for intraparietal separation might
provide is the preferability of the opposite approach (extraluminal
or endoluminal) and type implant (stays or miniballs respectively)
is better suited to the ductus, it ought not to be necessary to
perform a second test before the opposite procedure is initiated.
It is therefore, desirable that the results for these tests be
interconvertible. This is established by empirical testing with the
different tests of the same ductus.
[5018] XVII11. In Situ Muzzle-Head Adhesion Test
[5019] Since the implants are generally to be positioned uniformly
at close intervals, clinging or adhesion of the endothelium to the
sides of the muzzle-head, despite its nonthrombogenic
fluroropolymer coating, with the risk of rotational stretching
injury, must be avoided. The avoidance of adhesion is especially
important during automatic discharge, which can proceed so quickly
that the operator does not realize the problem to push the cancel
button. For this reason, smooth movement over the run segment is
confirmed before automatic discharge is initiated. A muzzle-head
with fluoropolymeric coating is intrinsically lubricious and, if
necessary, can additionally be coated with a lubricant as specified
above prior to introduction.
[5020] When the diameter of the lumen wall at the level to be
implanted becomes smaller relative to that of the muzzle-head,
especially when the condition of the wall promotes adhesion,
additional lubricant may be necessary. Once at an appropriate depth
into the vascular tree, rather than to test for adhesion by
manually rotating the barrel-assembly risking rotational injury to
the lumen wall, the turret-motor is used for controlled rotation
too slight for such injury to become significant. When the
muzzle-head reaches the level of the ductus for implantation, the
effect of attempting to rotate the muzzle-head to either side with
the turret-motor is observed for free movement, the tantalum
markings or indices on the muzzle-head assisting in this
determination.
[5021] While with either an angioplasty or nonangioplasty
barrel-assembly, the turret-motor is not normally used before
discharge, hence, before the barrel-assembly is connected to the
airgun, the test for adhesion of the lumen wall to the muzzle-head
and procedure for spreading lubricant about the muzzle-head once
introduced through a muzzle-port makes use of the turret-motor
prior to insertion in the airgun. Use of the turret-motor to check
adhesion or to spread lubricant or medication prior to initiating
discharge represents a distinct function of the turret-motor. If
previously connected to the airgun, the barrel-assembly may be
disconnected for such purpose.
[5022] The muzzle-head is rotated under closed-loop control and
moved transluminally or longitudinally by the linear stage stepper
motor under open-loop control. Resistance to rotation for any
reason will be quickly apparent as the lagging behind or cessation
of adherence to the instantaneous set point. Provided the
barrel-assembly is equipped with a fine angioscope or intravascular
ultrasound probe at the nose, resistance to tranluminal motion will
be seen in the video image monitor.
[5023] When observed, the turret-motor is stopped and a
service-catheter, or if available, an ejection tool-insert, is used
to eject a lubricant such as ACS Microslide.RTM., Medtronic
Enhance.RTM., Bard Pro/Pel.RTM. or Hydro/Pel.RTM., Cordis SLX.RTM.,
or Rotaglide.RTM. into the interface between the outer surface of
the muzzle-head and the endothelium. The turret-motor is then
rotated to either side (clockwise and counterclockwise) and
transluminal movement reattempted. If the barrel-assembly provides
no inmate viewing means, it is best to use a muzzle-head with a
contrast dye or tantalum coating which will be easily seen with an
extracorporeal imagning machine.
[5024] XVIII. Followup Examination
[5025] Once implanted, the status of stent-jackets, stent-stays,
clasp-magnets, clasp-wraps, and magnet-wraps should be periodically
reinspected. While every precaution is taken to prevent such
occurrences, stent-jackets may lose resilience, vascular intramural
implants (miniature balls, stays) and clasp prongs can be pulled
through the intervening substance of the vascular wall, and
magnetically retracted tunic or tunics may delaminate. The
embrittlement of a nonmagnetic stent-jacket would necessitate its
replacement.
[5026] Every stent known is subject to structural failure,
migration, or both. Endoluminal (conventional) ureteral stents, for
example, are known at the time of placement to require replacement,
but are nevertheless often disregarded if not forgotten. One
purpose of reexamination is to determine the extent if any of
reocclusion and use the remote heating capability of the
extralumnal stent to reopen the lumen by means of noninvasive
thermoplasty. The operator who realizes that he has stretched the
lumen can place a chain-stent over the affected area without
ductus-intramural implants for later noninvasive thermoplasty.
[5027] That compared to an endoluminal stent, the failure and/or
migration of a stent outside the ductus poses little threat of
occlusion is inarguable; however, the loss in patency is no less
serious. For examining an extraluminal implant, intraductal
ultrasonography is of little value. However, advances such as
dual-energy contrast-enhanced computed tomography allow visualizing
the current status of the different implants described herein, with
or without a die or tantalum indices on the surfaces of the
implants, noninvasively.
[5028] XIX. Sterilization
[5029] All of the components described herein, to include
sequential or line-feed preloaded clips; rotary magazine clips;
stent-jackets; subcutaneous encapsulated magnets;
barrel-assemblies, which may include a motorized turret; test
rotary magazine clips, airguns, stays, and stay insertion tools,
are packaged sterile. Miniballs are preferably dispensed in
preloaded clips as units with package markings to indicate proper
use, rather than sold loose or in bulk. Sterilization is most
preferred by radiation, followed by a gas, such as ethylene oxide,
a liquid, such as glutaraldehyde, and, when the apparatus contains
no bonds that heat might undo, boiling, steam autoclaving, and
heating.
[5030] Fibrous wraps are meant for one time use and eventual
disposal; however, if precautionary sterilization is to avert the
possibility of contamination following removal from the sterile
package, sterilization is by filtering through sterilizing gas or
liquid through the interstices or exposure to ionizing radiation.
Of the foregoing, sequential or line-feed preloaded clips, rotary
magazine clips, stent-jackets, and subcutaneous encapsulated
magnets are sold in sealed fully labelled paper envelopes with
laminated foil interior, are meant to be implanted, and not
sterilized after opening.
[5031] A more specialized and costly stent-jacket or subcutaneous
magnet that is opened in error can nevertheless be sterilized
chemically, as with ethylene oxide gas or radiation (reference,
International Standards Organization standard 11135, Medical
Devices--Validation and Routine Control of Ethylene Oxide
Sterilization, peroxide plasma, electron beam, or gamma radiation).
Alternative methods of sterilization should not be used with
magnets. The high temperatures of boiling or steam autoclaving can
degrade magnets, as can beta or gamma particle irradiation.
Barrel-assemblies, test clips, and airguns are permanent and
require sterilization by nondestructive means.
[5032] Barrel-assemblies are made of plastics, primarily
fluoropolymers, with muzzle-heads usually made of nonmagnetic
stainless steel and possibly motors that contain magnets; test
clips consist of plastics and metals; and airguns include canisters
containing compressed air or CO.sub.2, the latter a liquid while
contained and a gas when released, metals, plastics, and solenoids
containing magnets. Chemical sterilization is preferred as
applicable to all components. Suitable sterilizing agents include
ethylene oxide gas, glutaraldehyde, chlorine dioxide, and.other
chlorine preparations, to include Dakins solution and Javelle
water. Potentially irritating sterilizing agents are thoroughly
removed by washing in soap and water and rinsing before use or
packaging. Chemical sterilization cabinets, or chemiclaves,
generally generate heat that falls safely below the Curie
temperature of neodymium iron boron magnets.
[5033] XX. Exemplary Channel of Control in a Fully Implanted
Ambulatory Adaptive Hierarchical Control System for Automatic
Response to a Comorbid Condition
[5034] Without safe and secure means of connection to tubular
anatomical structures such as vessels, ducts, and the gut (ductus)
which remain free of degradation or leaks over a period of years,
an implantable automatic disorder response system is impossible.
With discomfort minimized during placement, such systems will
supplant current means of therapy for more serious chronic disease,
especially comorbid, and especially in patients not prescription
regimen compliance dependable. FIG. 107 shows an exemplary channel,
or arm, of control in a fully implanted real time adaptive
(`self-tuned,` learning-capable) and predictive hierarchical
control system for the monitoring of physiological indicia
pertinent to morbidity and comorbidity and the automatic dispensing
of drugs, metabolic substances, heat, and/or cold responsive
thereto to the sites or nidi of morbidity.
[5035] The benefits of direct pipe-targeting in preventing side
effects, drug-drug interactions, and isolating each drug, allowing
the qualitative and quantitative evaluation of the effect of each,
the effect of each in relation to each of the others, and in the
context of the homeostatic condition of the patient
notwithstanding, unless the schedule for self-administration of a
number of drugs is so complicated that it constitutes a nuisance
likely to result in unintentional noncompliance, an implanted
system is inappropriate for a competent adult patient for whom a
safe and effective therapeutic regimen already exists. Another
justification in such a patient that electrical or mechanical
devices are to be implanted in any event, so that to include
electrical and fluid lines to afford adjunctive treatment and
service these primary implants without the need to reopen the
patient is only common sense.
[5036] As shown in FIG. 108, the one of two or more channels of
morbidity responsive control assigned to the urinary tract is
treated in coordination with the other comorbidity or
comorbidities. In practice, additional levels of control are
necessary to deal with comorbidities, FIG. 108 simplified in this
regard. FIG. 107 shows the system fully implanted except for
surface ports, whereas FIG. 108 shows a system intended for shorter
term use and therefore withholding components that need not be
implanted housed within a power and control pack suspended from a
waist belt. Biotelemetry is addressed in this section and indicated
as one of a number of implanted microcircuit elements in FIG. 107,
but discussed in conjunction with FIG. 108 in relation to data
transmitted to the clinic or medical center.
[5037] This coordination, vertical from implanted [bio]sensors up
through the nodes of control for the urinary tract, down from the
master node for effector commands, and lateral for the other
morbidities which affect other organ systems at other sites, is
administered by the master node, executed by an implant
microcontroller as master controller. Materials developed since the
early 2000s consolidate sensor, or detector, and drug release
response functions in a single material; however, much as drug
eluting stents, these have nonreplenishable, hence limited, drug
delivery capability. Most such materials respond by directly and
spontaneously releasing medication pertinent to the exciting or
triggering stimulus without the ability to provide a control
signal, hence, are exclusively chemical, not really sensors, while
others have this ability.
[5038] This would remain so were the `nanocontainers` absorbable
and drug release inclusive of dissolution of the sensor/container
itself, something the ability to attract superparaagnetic iron
oxide nanoparticle-carried drugs infused as a nanofluid--which
stent- and impasse-jackets allow--would overcome (see, for example,
Trousil, J., Filippov, S. K., Hrub , M., Mazel, T., Syrova, Z., and
10 others 2017. "System with Embedded Drug Release and Nanoparticle
Degradation Sensor Showing Efficient Rifampicin Delivery into
Macrophages," Nanomedicine 13(1):307-315; Wang, J., Kaplan, J. A.,
Colson, Y. L., and Grinstaff, M. W. 2017. "Mechanoresponsive
Materials for Drug Delivery: Harnessing Forces for Controlled
Release," Advanced Drug Delivery Reviews 108:68-82; Wang, J.,
Colson, Y. L., and Grinstaff, M. W. 2017. "Tension-activated
Delivery of Small Molecules and Proteins from Superhydrophobic
Composites," Advanced Healthcare Materials December 27; Zhao, L.,
Huang, Q., Liu, Y., Wang, Q., Wang, L., and 3 others 2017. "Boronic
Acid as Glucose-sensitive Agent Regulates Drug Delivery for
Diabetes Treatment," Materials (Basel, Switzerland) 10(2). pii:
E170; Wu, J. Z., Williams, G. R., Li, H. Y., Wang, D., Wu, H., Li,
S. D., and Zhu, L. M. 2017. "Glucose- and Temperature-sensitive
Nanoparticles for Insulin Delivery," International Journal of
Nanomedicine 12:4037-4057; Matea, C. T., Mocan, T., Tabaran, F.,
Pop, T., Mosteanu, O., and 3 others 2017. "Quantum Dots in Imaging,
Drug Delivery and Sensor Applications," International Journal of
Nanomedicine 12:5421-5431;Zhao, L., Xiao, C., Wang, L., Gai, G.,
and Ding, J. 2016. "Glucose-sensitive Polymer Nanoparticles for
Self-regulated Drug Delivery," Chemical Communications (Cambridge,
England) 52(49):7633-7652; Tziveleka, L. A., Bilalis, P.,
Chatzipavlidis, A., Boukos, N., and Kordas, G. 2014. "Development
of Multiple Stimuli Responsive Magnetic Polymer Nanocontainers as
Efficient Drug Delivery Systems," Macromolecular Bioscience
14(1):131-141; Siegel, R. A. 2014. "Stimuli Sensitive Polymers and
Self Regulated Drug Delivery Systems: A Very Partial Review,"
Journal of Controlled Release 190:337-351; Ngoepe, M., Choonara, Y.
E., Tyagi, C., Tomar, L. K., du Toit, L. C., and 3 others 2013.
"Integration of Biosensors and Drug Delivery Technologies for Early
Detection and Chronic Management of Illness," Sensors (Basel,
Switzerland) 13(6):7680-7713; Vakili, H., Genina, N., Ehlers, H.,
Bobacka, J., and Sandler, N. 2012. "Using Ion-selective Electrodes
to Study the Drug Release from Porous Cellulose Matrices,"
Pharmaceutics 4(3):366-376; Bawa, P., Pillay, V., Choonara, Y. E.,
and du Toit, L. C. 2009. "Stimuli-responsive Polymers and Their
Applications in Drug Delivery," Biomedical Materials (Bristol,
England) 4(2):022001; Qu, J., Chu, L., Li, Y., Chen, W., and Zheng,
C. 2004. "Intelligent Polymeric Systems for Glucose-responsive
Insulin Delivery," in Chinese with English abstract at Pubmed,
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi [Journal of Biomedical
Engineering] 21(6):1028-1030).
[5039] The lowest level nodes that execute direct control consist
of microcontrollers, the hierarchical levels above these of equal
or progressively increased computing power, the master controller
generally that most powerful a microprocessor. Except at the direct
control level, the ascription of `supervisory` or coordinative
functions vertically and horizontally is not fixed, so that
side-by-side comparison can vary as to execution at the same or
next higher level. The microcontrollers as nodes can be positioned
in a distributed arrangement, but ultrahigh density electronics
makes possible consolidation within a common enclosure.
[5040] This form of control is further described below and in
copending application Ser. No. 14/121,365. Urological problems a
frequent comorbidity in the elderly, the example shown in FIG. 107
pertains to the urinary tract. FIG. 107 shows nonjacketing
side-entry connector 325 fastened toward the front of the
inferolateral surface of the urinary bladder where it is positioned
to treat any of a number of bladder dysfunctions. Such connectors,
equivalent to ductus side-entry jackets where connection is to a
tissue surface rather than a jacketable structure are also
described in copending application Ser. No. 14/121,365. Whereas
ductus side-entry jackets are used to connect fluid and electrical
lines to vessels and other tubular anatomical structures,
nonjacketing side-entry connectors are used to connect fluid and
electrical lines to the outer surface of an organ or to tissue.
[5041] Nonjacketing side-entry connectors can incorporate hollow
electrified anchoring needles for the injection of drugs and other
agents into the substrate anchoring tissue, here the wall of the
bladder, and the distal end of line 317 can be used to instill
medication into the bladder cavity. In FIG. 107, part number 315 is
a body surface port, here shown as positioned subdermally, so that
drugs are introduced into reservoir 316 by hypodermic needle
injection or jet injector. In a nonpermanent application, part
number 315 is generally a portacath or mediport. When the surface
port includes an outflow, or excurrent, opening, such as that shown
as part number 323 to emit urine, or a compartment to house a
button cell type battery or rechargeable button cell, or electrical
socket to recharge an implanted battery, these if not all openings
in the port are mounted cutaneously, that is, on rather than
beneath, the skin.
[5042] While unlikely, should the power requirements, or the number
of reservoirs or pumps become prohibitive of implantation, these
are relegated to a belt- or thigh-worn control, power, and pump
pack. Generally, once one of these becomes too large or numerous,
the wearing of an external pack required in any event, the other
components are likewise relegated to the pack, only the sensors
requiring to be implanted. The power requirement permitting, a
compartment in an above-skin-mounted, or cutaneous, port at the
body surface to store one or more button cell batteries or
rechargeable batteries, or an electrical socket to allow connection
to a power supply, eliminates the need for transdermal, or
`transcutaneous,` energy transfer and the need to implant the
reception and energy conversion circuitry associated therewith.
[5043] With a competent patient, this is usually to be preferred,
both because it eliminates the additional implanted componentry and
makes possible essentially uninterrupted duty by having the patient
carry a small self-contained battery charger, power supply, or
spare batteries. When smaller, such as a rechargeable button cell,
the battery can be implanted, and as indicated above, recharged
either through a socket in the surface port or transcutaneously
recharged. An external (extracorporeal) control, power, and pump
pack can include a larger battery or power supply with power cord
to plug in the cutaneous body surface port, or can avoid the need
for a cord with transcutaneous transmission circuitry. Generally,
the current limitations of orientation, distance, and the need to
implant a reception antenna make transcutaneous recharging less
desirable, the more so in a cognitively impaired or very young
patient. Simultaneous transdermal energy transfer and data
transmission/instruction reception is addressed below in this
section.
[5044] When no port at the body surface is used, recharging of
implants is by transdermal or transcutaneous energy transfer (see,
for example, Agarwal, K., Jegadeesan, R., Guo, Y. X., and Thakor,
N. V. 2017. "Wireless Power Transfer Strategies for Implantable
Bioelectronics," Institute of Electrical and Electronics Engineers
Reviews in Biomedical Engineering 10:136-161; Bocan, K. N., Mickle,
M. H., and Sejdic, E. 2017. "Tissue Variability and Antennas for
Power Transfer to Wireless Implantable Medical Devices," Institute
of Electrical and Electronics Engineers Journal of Translational
Engineering in Health and Medicine 5:2700111; Agarwal, K.,
Jegadeesan, R., Guo, Y. X., and Thakor, N. V. 2017. "Wireless Power
Transfer Strategies for Implantable Bioelectronics: Methodological
Review," Institute of Electrical and Electronics Engineers Reviews
in Biomedical Engineering March 16 (in press); Mirbozorgi, S. A.,
Yeon, P., and Ghovanloo, M. 2017. "Robust Wireless Power
Transmission to mm-Sized Free-floating Distributed Implants,"
Institute of Electrical and Electronics Engineers Transactions on
Biomedical Circuits and Systems 11(3):692-702; Bocan, K. N. and
Sejdi , E. 2016. "Adaptive Transcutaneous Power Transfer to
Implantable Devices: A State of the Art Review," Sensors (Basel,
Switzerland) 16(3). pii: E393; Schormans, M., Valente, V., and
Demosthenous, A. 2016. "Frequency Splitting Analysis and
Compensation Method for Inductive Wireless Powering of Implantable
Biosensors, Sensors (Basel, Switzerland) 16(8). pii: E1229; Ahn, D.
and Ghovanloo, M. 2016. "Optimal Design of Wireless Power
Transmission Links for Millimeter-sized Biomedical Implants,"
Institute of Electrical and Electronics Engineers Transactions on
Biomedical Circuits and Systems 10(1): 125-137; Radziemski, L. and
Makin, I. R. 2016. "In Vivo Demonstration of Ultrasound Power
Delivery to Charge Implanted Medical Devices via Acute and Survival
Porcine Studies," Ultrasonics 64:1-9; Ibrahim, A. and Kiani, M.
2016. "A Figure-of-Merit for Design and Optimization of Inductive
Power Transmission Links for Millimeter-sized Biomedical Implants,"
Institute of Electrical and Electronics Engineers Transactions on
Biomedical Circuits and Systems 10(6):1100-1111; Ibrahim, A. and
Kiani, M. 2016. "Inductive Power Transmission to Millimeter-sized
Biomedical Implants Using Printed Spiral Coils," Conference
Proceedings Institute of Electrical and Electronics Engineers
Engineering in Medicine and Biology Society 2016:4800-4803; Miao,
M. and Kiani, M. 2016. "Optimal Resonance Configuration for
Ultrasonic Wireless Power Transmission to Millimeter-sized
Biomedical Implants," Conference Proceedings Institute of
Electrical and Electronics Engineers Engineering in Medicine and
Biology Society 2016:1934-1937; Godfraind, C., Debelle, A., Lonys,
L., Acuna, V., Doguet, P., and Nonclercq, A. 2016. "Inductive
Powering of Subcutaneous Stimulators: Key Parameters and Their
Impact on the Design Methodology," European Journal of
Translational Myology 26(2):6040; Schormans, M., Valente, V., and
Demosthenous, A. 2015. "Efficiency Optimization of Class-D
Biomedical Inductive Wireless Power Transfer Systems by Means of
Frequency Adjustment," Conference Proceedings Institute of
Electrical and Electronics Engineers Engineering in Medicine and
Biology Society 2015:5473-5476; Ben Amar, A., Kouki, A. B., and
Cao, H. 2015. "Power Approaches for Implantable Medical Devices,"
Sensors (Basel, Switzerland) 15(11):28889-28914; Ibrahim, A. and
Kiani, M. 2015. "Safe Inductive Power Transmission to
Millimeter-sized Implantable Microelectronics Devices," Conference
Proceedings of the Annual International Conference of the Institute
of Electrical and Electronics Engineers Engineering in Medicine and
Biology Society 2015:817-820; RamRakhyani, A. K. and Lazzi, G.
2014. "Multi-coil Approach to Reduce Electromagnetic Energy
Absorption for Wirelessly Powered Implants," Healthcare Technology
Letters 1(1):21-25; Ho, J. S., Yeh, A. J., Neofytou, E., Kim, S.,
Tanabe, Y., Patlolla, B., Beygui, R. E., and Poon, A. S. 2014.
"Wireless Power transfer to Deep-tissue Microimplants," Proceedings
of the National Academy of Sciences of the United States of America
111(22):7974-7979; Eom, K., Jeong, J., Lee, T. H., Lee, S. E., Jun,
S. B., and Kim, S. J. 2013. "Columnar Transmitter Based Wireless
Power Delivery System for Implantable Device in Freely Moving
Animals," Conference Proceedings Institute of Electrical and
Electronics Engineers Engineering in Medicine and Biology Society
2013:1859-1862; Li, X., Zhang, H., Peng, F., Li, Y., Yang, T.,
Wang, B., and Fang, D. 2012. "A Wireless Magnetic Resonance Energy
Transfer System for Micro Implantable Medical Sensors," Sensors
(Basel, Switzerland) 12(8):10292-10308; Artan, N., Vanjani, H.,
Vashist, G., Fu, Z., Bhakthavatsala, S., Ludvig, N., Medveczky, G.,
and Chao, H. 2010. "A High-performance Transcutaneous Battery
Charger for Medical Implants," Proceedings of the Institute of
Electrical and Electronics Engineers Engineering in Medicine and
Biology Society Annual Conference 2010:1581-1584; Zhang, F.,
Hackworth, S. A., Liu, X., Chen, H., Sclabassi, R. J., and Sun, M.
2009. "Wireless Energy Transfer Platform for Medical Sensors and
Implantable Devices," Annual Conference Proceedings of the
Institute of Electrical and Electronics Engineers Engineering in
Medicine and Biology Society 2009:1045-1048) to recharge an
implanted battery.
[5045] The need for openings to the exterior for excurrent flow, to
withdraw test samples, or to house a battery or electrical socket,
for example, does not mean that other portions of the port are not
positioned subdermally. Cutaneous ports include a protective cover
and configuration to facilitate the wetting of all drug entry
openings with antimicrobials or anti-inflammatories as necessary.
Additionally, in FIG. 107, part number 317 is the catheteric line
conveying drugs, for example, from reservoir outlet pump 318 to and
through nonjacketing side-entry connecter 325. Reversible pump 318
allows the incurrent, or inflow, delivery of drugs and the
excurrent, or outflow, recovery, or aspiration, of diagnostic test
samples.
[5046] Connection of a more powerful suction pump to an opening in
the external port allows the withdrawal of test samples from within
the wall of the bladder; such use pertinent to diagnosis of a
neoplasm or interstitial cystitis, for example. In incurrent use,
line 317 can pass miniature cabled devices into the cavity of the
bladder. Battery 322 is of the miniature button cell type, which to
yield more power can be ganged. To meet the power requirements
where numerous conditions necessitate numerous power consuming
components, these are connected in series or parallel as
appropriate with little combined weight to cause discomfort.
Whether implanted as shown in FIG. 107 or housed in a compartment
within surface port 315, battery 322 supplies the current
responsive to the switching commands of microcontroller implant
321.
[5047] Microcontroller implant 321 is shown housed together with
transdermal charging circuitry 319, and can be secured by suture or
in a pocket, if necessary, created by tissue expansion cognizant of
the risks associated therewith (Razzak, M. A., Hossain, M. S.,
Radzi, Z. B., Yahya, N. A., Czernuszka, J., and Rahman, M. T. 2016.
"Cellular and Molecular Responses to Mechanical Expansion of
Tissue," Frontiers in Physiology 7:540; Yu, Q., Sheng, L., Yang,
M., Zhu, M., Huang, X., and Li, Q. 2014. "Tanshinon IIA Injection
Accelerates Tissue Expansion by Reducing the Formation of the
Fibrous Capsule," Public Library of Science One 9(8):e105756) in
the pectoral region or sutured within the abdominal cavity. Part
numbers 319, 321, and 327 have nominal component designations but
should be understood as embracing a number of different components
which vary according to the specific application. Representation
thus spares the visual clutter that minimizes the actual space the
anatomy provides for positioning these, since there is not just the
two dimensional space of a drawing but any number of positions for
placement in depth.
[5048] Wireless, or Bluetooth, ultra-low energy transmission and
reception between sensors and primary nodes and among nodes to
eliminate wires as addressed below in section XXI. is one type of
componentry that may be understood as encompassed in any of these
part numbers (see, for example, Walsh, J., Roberts, R., Morris, R.,
and Heinemann, L. 2015. "Device Connectivity: The Next Big Wave in
Diabetes," Journal of Diabetes Science and Technology 9(3):701-705;
Omre, A. H. 2010. "Bluetooth Low Energy: Wireless Connectivity for
Medical Monitoring," Journal of Diabetes Science and Technology
4(2):457-463; Gomez, C, Oller, J., and Paradells, J. 2012.
"Overview and Evaluation of Bluetooth Low Energy: An Emerging
Low-Power Wireless Technology," Sensors (Basel, Switzerland)
12(9):11734-11753).
[5049] Typically, part number 327 would represent an
intracorporeal, or within the body, transdermal battery charging
and receiving circuitry and secondary coil or antenna, and
optionally, a diagnostic [bio]sensor output data transceiver and
biotelemetry antenna (see, for example, Mao, S., Wang, H., Zhu, C.,
Mao, Z. H., and Sun, M. 2017. "Simultaneous Wireless Power Transfer
and Data Communication Using Synchronous Pulse-controlled Load
Modulation," Measurement (London, England) 109:316-325; Bradley, P.
D. 2011. "Wireless Medical Implant Technology--Recent Advances and
Future Developments," Proceedings of the European Solid-State
Device Research Conference, at
http://ieeexplore.ieee.org/document/6044235/; Sharma, V., McCreery,
D. B., Han, M., and Pikov, V. 2010. "Bidirectional Telemetry
Controller for Neuroprosthetic Devices," Institute of Electrical
and Electronics Engineers Transactions on Neural Systems and
Rehabilitation Engineering 18(1):67-74; Young, D. J. 2009.
"Wireless Powering and Data Telemetry for Biomedical Implants,"
Institute of Electrical and Electronics Engineers Engineering in
Medicine and Biology Society Annual Conference Proceedings
2009:3221-3224; Panescu, D. 2008. "Wireless Communication Systems
for Implantable Medical Devices," Institute of Electrical and
Electronics Engineers Engineering in Medicine and Biology Magazine
27(2):96-101; Farshchi, S., Pesterev, A., Nuyujukian, P. H., Mody,
I., and Judy, J. W. 2007. "Bi-Fi: An Embedded Sensor/System
Architecture for REMOTE Biological Monitoring," Institute of
Electrical and Electronics Engineers Transactions on Information
Technology in Biomedicine 11(6):611-618; Farshchi, S., Nuyujukian,
P. H., Pesterev, A., Mody, I., and Judy, J. W. 2006. "A
TinyOS-enabled MICA2-based Wireless Neural Interface," Institute of
Electrical and Electronics Engineers Transactions on Biomedical
Engineering 53(7):1416-1424; Neihart, N. M. and Harrison, R. R.
2005. "Micropower Circuits for Bidirectional Wireless Telemetry in
Neural Recording Applications," Institute of Electrical and
Electronics Engineers Transactions on Biomedical Engineering
53(7):1416-1424; 52(11):1950-1959; Valdastri, P., Menciassi, A.,
Arena, A., Caccamo, C., and Dario, P. 2004. "An Implantable
Telemetry Platform System for In Vivo Monitoring of Physiological
Parameters," Institute of Electrical and Electronics Engineers
Transactions on Information Technology in Biomedicine 8(3):271-278;
Guler, N. F. and Ubeyli, E. D. 2002. "Theory and Applications of
Biotelemetry," Journal of Medical Systems 26(2):159-178;).
Side-entry jackets housing sensors that require a detectable
reagent or reagents to be taken up by the blood or urine, for
example, flowing past as to necessitate periodic replenishment are
supported by release through a ductus side-entry jacket positioned
upstream. Such a sensor or sensors housed within nonjacketing
side-entry connectors are fed the reagents through the integral
accessory channel
[5050] In cases of comorbidity which can be treated and diagnosed
without the need for a surface port with external openings,
implanting a transdermally rechargeable battery allows full, or
closed-skin, implantation. Part number 320 is a catheteric line to
pass urine from the bladder through nonjacketing side-entry
connector 326 to and through cutaneous surface outlet port 323 and
into external urinary drainage collection bag 324. Where delivery
through the connector to the treatment site of radioactive fluids
would be sufficiently advantageous, the delivery apparatus from
body surface port to and through the connector, to include
reservoirs, feedlines, and connectors, are radiation shielded with
relatively light weight tungsten shielding.
[5051] Referring to FIG. 107, nonjacketing side-entry connector 325
when placed to treat an overactive, or `nervous,` bladder would
most often deliver electrical current through its electrified
anchoring needles and/or incorporate an electrode to pass current
into fibers of the superior and inferior hypogastric plexuses and
parasympathetic fibers of the pelvic splanchnic nerves, and/or a
catheteric line with hypotube to inject botulinum toxin (electrical
neurostimulation, electrostimulation). Current used thus is often
pulsed, this function generated by the implant microcontroller.
Overactive bladder has significant prevalence both as a separate
entity and as a comorbidity, commonly with diabetes.
[5052] Ductus side-entry jackets and nonjacketing side-entry
connectors make possible leak-free, and ductus side-entry jackets
make possible shear stress-free continuity between the lumina of
one or more catheters and those native without injuring the small
vessels and nerves about the adventitia and therefore the
urothelium. Both are therefore able to incorporate and stabilize in
position as necessary, condition-pertinent [bio]sensors, miniature
cabled diagnostic and therapeutic devices such as a laser,
temperature [bio]sensor/heating or cooling devices,
electrostimulatory electrode, intravascular ultrasound probe, or
any styloid diagnostic device.
[5053] As shown in FIG. 107, effectors, or actuators, other than
those positioned aside from the side-entry connector or jacket
comprise drug reservoir outlet pump 318 connecting reservoir 316 to
nonjacketing side-entry connector 325. Other such lines not shown
simultaneously feed other nonjacketing side-entry connectors and
ductus side-entry jackets. That is, a more inclusive view of the
implant system overall than that shown in FIG. 107 would show
ductus side-entry jackets, impasse-jackets, and nonjacketing
side-entry connectors assigned and positioned to treat morbidity
affecting other organ systems at separate locations via adjacent
channels of control in the hierarchy coordinated with that urinary
shown.
[5054] The prescription program uses these components in a
coordinated manner to return abnormal function to as normal overall
as can be attained with the anatomy given. Common instances of
comorbidity include asthma, often found together with " . . .
coronary artery disease, diabetes, dyslipidemia, hypertension,
epilepsy, inflammatory bowel disease, rheumatic diseases, and
severe psychiatric disease," the incidence of such comorbidity
increasing with age (Kauppi, P., Linna, M., Jantunen, J.,
Martikainen, J. E., Haahtela, T., Pelkonen, A., and Makela, M.
2015. "Chronic Comorbidities Contribute to the Burden and Costs of
Persistent Asthma," Mediators of Inflammation 2015:819194). Asthma
associated with allergic rhinitis and atopic eczema, constitutes
the relatively common condition of atopy. All of these
comorbidities can be severe enough to justify treatment with a
fully implanted system of the kind described. The asthma may or may
not have been triggered or aggravated by the comorbidity.
[5055] Taking asthma as a comorbidity, treatment varies according
to the frequency of exacerbations or flare-ups. When not severe, a
drug compliance competent patient can ameliorate the obstruction
and distress with the aid of inhalants and oral drugs, so that if
the patient does not react adversely to an anti-asthmatic drug that
would help, the asthmatic drug delivery component can be omitted
from the implanted system. However, because in comorbidity, the
summary effect on the overall physiology of the patient of the
drugs taken must be monitored, coordinated, and the optimal regimen
continuously adjusted, the sensors and master controller program
must be included. Also targeted must be radiocontrast agents to
view bronchospasm if the use thereof induces nephropathy, thyroid
dysfunction, adverse drug-drug, drug-food, interactions, and/or
hypersensitivity reactions not readily avoidable by abstaining from
food that provokes allergic reactions.
[5056] Because the morbidities in a comorbid condition are treated
with minimal presuppositions as to the various designations of
disease, the system will respond whether bronchospasm, for example,
is excited by asthma, emphysema, or chronic obstructive pulmonary
disease. This materially reduces the acuity of treatment to
dependency on a preliminary diagnosis. When the drugs that would
best treat the symptoms and diagnostic agents that would best bring
an adverse reaction to view were the patient not constitutionally
dyspathetic to these, the drugs and agents are directly
pipe-targeted to the connector at the treatment site, with a
bronchospasm provoking condition such as asthma, primarily ductus
side-entry jackets on the bronchi and main pulmonary arteries.
[5057] Where medicinal inhalants, even when formulated for
immediate uptake, are absorbed directly into the venous tree and
other drugs into the arterial tree for dispersal throughout the
circulatory system, directly piping drugs to the major supply
arteries, even without the use of magnetized ductus side-entry
jackets as described in copending application Ser. No. 14,121,365,
now 20160051806, isolates the drug or drugs from the blood stream
until released directly at the target tissue (see, for example,
Ali, M. E., McConville, J. T., and Lamprecht, A. 2015. "Pulmonary
Delivery of Anti-inflammatory Agents," Expert Opinion on Drug
Delivery 12(6):929-945; Lee, W. H., Loo, C. Y., Traini, D., and
Young, P. M. 2015. "Nano- and Micro-based Inhaled Drug Delivery
Systems for Targeting Alveolar Macrophages," Expert Opinion on Drug
Delivery 12(6):1009-1026; Ibrahim, M. and Garcia-Contreras, L.
2013. "Mechanisms of Absorption and Elimination of Drugs
Administered by Inhalation," Therapeutic Delivery 4(8):1027-1045;
Labiris, N. R. and Dolovich, M. B. 2003. "Pulmonary Drug Delivery.
Part I: Physiological Factors Affecting Therapeutic Effectiveness
of Aerosolized Medications," British Journal of Clinical
Pharmacology 56(6):588-599; Labiris, N. R. and Dolovich, M. B.
2003. "Pulmonary Drug Delivery. Part II: The Role of Inhalant
Delivery Devices and Drug Formulations in Therapeutic Effectiveness
of Aerosolized Medications," British Journal of Clinical
Pharmacology 56(6):600-612; Lipworth, B. J. 1996. "Pharmacokinetics
of Inhaled Drugs," British Journal of Clinical Pharmacology
42(6):697-705;). Little residue continuing forward through the
circulation, side effects and interactions with other drugs or food
are considerably reduced if not eliminated.
[5058] As is true of all drugs to be targteted to a specific organ
or tissue, all drugs to include those delivered in nanoparticulate
form, magnetically susceptibly carried or not, for delivery to the
lungs are more effectively delivered when directly piped. Release
within the lungs by these means are applicable to any
intrapulmonary disorder and any drugs used conventionally to treat
each condition, radiation shielded lines and ductus side-entry
connectors allowing the direct targeting of a malignancy (see, for
example, Mangal, S., Gao, W., Li, T., and Zhou, Q. T. 2017.
"Pulmonary Delivery of Nanoparticle Chemotherapy for the Treatment
of Lung Cancers: Challenges and Opportunities," Acta Pharmacologica
Sinica 38(6):782-797; Longest, P. W. and Hindle, M. 2017. "Small
Airway Absorption and Microdosimetry of Inhaled Corticosteroid
Particles after Deposition," Pharmaceutical Research
34(10):2049-2065; Din, F. U., Aman, W., Ullah, I., Qureshi, O. S.,
Mustapha, O., Shafique, S., and Zeb, A. 2017. "Effective Use of
Nanocarriers as Drug Delivery Systems for the Treatment of Selected
Tumors," International Journal of Nanomedicine 12:7291-7309;
Ferraz-Carvalho, R. S., Pereira, M. A., Linhares, L. A.,
Lira-Nogueira, M. C., Cavalcanti, I. M., Santos-Magalhaes, N. S.,
and Montenegro, L. M. 2016. "Effects of the Encapsulation of Usnic
Acid into Liposomes and Interactions with Antituberculous Agents
Against Multidrug-resistant Tuberculosis Clinical Isolates,"
Memorias do Instituto Oswaldo Cruz [Memoirs of the Oswaldo Cruz
Institute] 111(5):330-334; Brandt, C., Thronicke, A., Roehmel, J.
F., Krannich, A., Staab, D., and Schwarz, C. 2016. "Impact of
Long-Term Tiotropium Bromide Therapy on Annual Lung Function
Decline in Adult Patients with Cystic Fibrosis," Public Library of
Science One 11(6):e0158193; Perez-Herrero, E. and
Fernandez-Medarde, A. 2015. "Advanced Targeted Therapies in Cancer:
Drug Nanocarriers, the Future of Chemotherapy," European Journal of
Pharmaceutics and Biopharmaceutics 93:52-79; Ali, M. E.,
McConville, J. T., and Lamprecht, A. 2015. "Pulmonary Delivery of
Anti-inflammatory Agents," Expert Opinion on Drug Delivery
12(6):929-945; Pham, D. D., Fatal, E., and Tsapis, N. 2015.
"Pulmonary Drug Delivery Systems for Tuberculosis Treatment,"
International Journal of Pharmaceutics 478(2):517-529; Barnes, P.
J. 2013. "Development of New Drugs for COPD," Current Medicinal
Chemistry 20(12):1531-1540; Bailey, M. M. and Berkland, C. J. 2009.
"Nanoparticle Formulations in Pulmonary Drug Delivery," Medical
Research Reviews 29(1):196-212; Sung, J. C., Pulliam, B. L., and
Edwards, D, A. 2007. "Nanoparticles for Drug Delivery to the
Lungs," Trends in Biotechnology 25(12):563-570).
[5059] Simple or comorbid, no disease, to include pulmonary, fails
to present plural physiological indicia for each of which sensors
cannot be devised to diagnose the condition, and with a form factor
to allow mounting within ductus side-entry jackets and nonjacketing
side-entry connectors. Pertinently, the small precise sensors
currently under development either necessitate or would be
materially improved by means such as nonjacketing side-entry
connectors and ductus side-entry jackets to fix these in
intracorporeal position as safely and stably as can be accomplished
(see, for example, Yang, Q. F., Lu, T. T., Shu, C. M., Feng, L. F.,
Chang, H. T., and Ji, Q. Y. 2017. "Eosinophilic Biomarkers for
Detection of Acute Exacerbation of Chronic Obstructive Pulmonary
Disease with or without Pulmonary Embolism," Experimental and
Therapeutic Medicine 14(4):3198-3206; Robison, H. M. and Bailey, R.
C. 2017. "A Guide to Quantitative Biomarker Assay Development Using
Whispering Gallery Mode Biosensors," Current Protocols in Chemical
Biology 9(3):158-173; Kim, E., Baaske, M. D., and Vollmer, F. 2017.
"Towards Next-generation Label-free Biosensors: Recent Advances in
Whispering Gallery Mode Sensors," Lab on a Chip 17(7):1190-1205;
Su, J. 2017. "Label-free Biological and Chemical Sensing Using
Whispering Gallery Mode Optical Resonators: Past, Present, and
Future," Sensors (Basel, Switzerland) 17(3). pii: E540; Dell'Olio,
F., Conteduca, D., De Palo, M., and Ciminelli, C. 2017. "Design of
a New Ultracompact Resonant Plasmonic Multi-Analyte Label-free
Biosensing Platform," Sensors (Basel, Switzerland) 17(8). pii:
E1810; Pongruengkiat, W. and Pechprasarn, S. 2017.
"Whispering-gallery Mode Resonators for Detecting Cancer," Sensors
(Basel, Switzerland) 17(9). pii: E2095; Luo, B., Wu, S., Zhang, Z.,
Zou, W., Shi, S., and 8 others 2016. "Human Heart Failure Biomarker
Immunosensor Based on Excessively Tilted Fiber Gratings,"
Biomedical Optics Express 8(1):57-67; Bianucci, P. 2016. "Optical
Microbottle Resonators for Sensing," Sensors (Basel, Switzerland)
16(11). pii: E1841; Bakakos, P, Patentalakis, G., and Papi, A.
2016. "Vascular Biomarkers in Asthma and COPD," Current Topics in
Medicinal Chemistry 16(14):1599-1609; Washburn, A. L., Shia, W. W.,
Lenkeit, K. A., Lee, S. H., and Bailey, R. C. 2016. "Multiplexed
Cancer Biomarker Detection Using Chip-integrated Silicon Photonic
Sensor Arrays," Analyst 141(18):5358-5365; Righini, G. C. and
Soria, S. 2016. "Biosensing by WGM [whispering gallery mode]
Microspherical Resonators," Sensors (Basel, Switzerland) 16(6).
pii: E905; Dell'Olio, F., Conteduca, D., Ciminelli, C., and
Armenise, M. N. 2015. "New Ultrasensitive Resonant Photonic
Platform for Label-free Biosensing," Optics Express
23(22):28593-28604; Soteropulos, C. E. and Hunt, H. K. 2012.
"Attaching Biological Probes to Silica Optical Biosensors Using
Silane Coupling Agents," Journal of Visualized Experiments
(63):e3866).
[5060] Drugs used to alleviate bronchospasm include muscarinic
acetylcholine receptor antagonists such as ipratropium bromide,
oxitropium bromide, and tiotropium bromide, conventionally
administered by inhaler or nebulizer, and beta 2 agonists such as
terbutaline, salbutamol, and fenoterol for shorter, salmeterol for
longer duration treatment, and epinephrine. Limiting consideration
to these few drugs, as a smooth muscle contracting, or positive
inotropic agent, ipratropium bromide can induce urinary outflow
obstruction, especially in men with prostatic hypertrophy
(Lozewicz, S. 1989. "Bladder Outflow Obstruction Induced by
Ipratropium Bromide," Postgraduate Medical Journal
65(762):260-261), supraventricular tachycardia (O'Driscoll, B. R.
1989. "Supraventricular Tachycardia Caused by Nebulised Ipratropium
Bromide," Thorax 44(4):312), bronchoconstriction (Rafferty, P.,
Beasley, R., Howarth, P. H., Mann, J. S., and Holgate, S. T. 1986.
"Bronchoconstriction Induced by Nebulised Ipratropium Bromide:
Relation to the Bromide Ion," British Medical Journal (Clinical
Research Edition) 293(6561):1538-1539; Mann, J. S., Howarth, P. H.,
Holgate, S. T. 1984. "Bronchoconstriction Induced by Ipratropium
Bromide in Asthma: Relation to Hypotonicity," British Medical
Journal (Clinical Research Edition) 289(6443):469), and less
commonly, secretory suppressive side effects, to include inhibition
of salivation, ocular effects such as pupil size, visual acuity,
intraocular pressure, and hemodynamic effects such as heart rate,
blood pressure, and blood gas changes (Anderson, W. M. 1986.
"Hemodynamic and Non-bronchial Effects of Ipratropium Bromide,"
American Journal of Medicine 81(5A):45-53).
[5061] In asthmatic children, the short-acting beta 2 agonists
terbutaline, salbutamol, and fenoterol induce tremor within 5
minutes, more intense with salbutamol. Terbutaline induces
bradycardia, whereas salbutamol and fenoterol induce tachycardia
more intense than the bradycardia induced by terbutaline. A double
dose of salbutamol compared to the other two is equally effective,
but at the expense of more intense tremor and tachycardia
(Vangveeravong, M. 2008. "A Comparative Study of Efficacy of
Salbutamol via Metered Dose Inhaler with Volumatic Spacer and via
Dry Powder Inhaler, Easyhaler, to Nebulization in Mild to Moderate
Severity Acute Asthma Exacerbation in Childhood," Journal of the
Medical Association of Thailand 91 Supplement 3:S115-S123;
Scalabrin, D. M., Sole, D., and Naspitz, C. K. 1996. "Efficacy and
Side Effects of Beta 2-agonists by Inhaled Route in Acute Asthma in
Children: Comparison of Salbutamol, Terbutaline, and Fenoterol,"
Journal of Asthma 33(6):407-415; "Newhouse, M. T., Dolovich, M. B.,
and Kazim, F. 1994. "Dose-effect Relationship of the Beta-agonists
Fenoterol and Salbutamol in Patients with Asthma," Chest
105(6):1738-1742; Scalabrin, D. M. and Naspitz, C. K. 1993.
"Efficacy and Side Effects of Salbutamol in Acute Asthma in
Children: Comparison of Oral Route and Two Different Nebulizer
Systems," Journal of Asthma 30(1):51-59; Wong, C. S., Pavord, I.
D., Williams, J., Britton, J. R., and Tattersfield, A. E. 1990.
"Bronchodilator, Cardiovascular, and Hypokalaemic Effects of
Fenoterol, Salbutamol, and Terbutaline in Asthma," Lancet
336(8728):1396-1399; Budmiger H, Kyd K, and Scherrer, M.1978. "The
Bronchospasmolytics Salbutamol, Fenoterol, Terbutaline and
Reproterol. Their Effects and Side Effects in Asthmatics after
Inhalation with an Electric Nebulizer," (in German with English
abstract at Pubmed), Schweizerische Medizinische Wochenschrift
[Swiss Medical Weekly] 108(31):1190-1197; Watson, J. M. and
Richens, A. 1974. "The Effects of Salbutamol and Terbutaline on
Physiological Tremor, Bronchial Tone and Heart Rate," British
Journal of Clinical Pharmacology 1(3):223-227).
[5062] Even in a patient without a special sensitivity to it, the
sympathomimetic amine epinephrine can induce a pronounced sense of
agitation or disquietude, and in response to even a small overdose,
pronounced distress. These are not, strictly speaking, adverse side
effects, but rather the normal consequences of releasing the
hormone into the bloodstream. By significantly reducing if not
eliminating the release into the general circulation of
epinephrine, for example, directly targeted delivery can alleviate
such reactions no less than adverse reactions. Adverse side effects
are associated with use in patients with known hypersensitivity and
in patients with narrow angle, or angle closure, glaucoma, these
too avoided by the substantial sequestration from the bloodstream
provided by direct pipe-targeting.
[5063] Epinephrine can, however, react with certain foods and
anesthetics with alarming, potentially fatal, consequences (see,
for example, Lasemi, E., Sezavar, M., Habibi, L., Hemmat, S.,
Sarkarat, F., and Nematollahi, Z. 2015. "Articaine (4%) with
Epinephrine (1:100,000 or 1:200,000) in Inferior Alveolar Nerve
Block: Effects on the Vital Signs and Onset, and Duration of
Anesthesia," Journal of Dental Anesthesia and Pain Medicine
15(4):201-205; Abu-Mostafa, N., Al-Showaikhat, F., Al-Shubbar, F.,
Al-Zawad, K., and Al-Zawad, F. 2015. "Hemodynamic Changes Following
Injection of Local Anesthetics with Different Concentrations of
Epinephrine During Simple Tooth Extraction: A Prospective
Randomized Clinical Trial," Journal of Clinical and Experimental
Dentistry 7(4):e471-e476; Abu-Mostafa, N., Aldawssary, A., Assari,
A., Alnujaidy, S., and Almutlaq, A. 2015. "A Prospective Randomized
Clinical Trial Compared the Effect of Various Types of Local
Anesthetics Cartridges on Hypertensive Patients During Dental
Extraction," Journal of Clinical and Experimental Dentistry
7(1):e84-e88; Steinfort, D. P., Herth, F. J., Eberhardt, R., and
Irving, L. B. 2013. "Reply: Endobronchial Epinephrine: Confusion is
in the Air," American Journal of Respiratory and Critical Care
Medicine 187(10):1138; Khoo, K. L., Lee, P., and Mehta, A. C. 2013.
"Endobronchial Epinephrine: Confusion is in the Air," American
Journal of Respiratory and Critical Care Medicine
187(10):1137-1138; Steinfort, D. P., Herth, F. J., Eberhardt, R.,
and Irving, L. B. 2012. "Potentially Fatal Arrhythmia Complicating
Endobronchial Epinephrine for Control of Iatrogenic Bleeding,"
American Journal of Respiratory and Critical Care Medicine
185(9):1028-1030; Becker, D. E. 2012. "Basic and Clinical
Pharmacology of Autonomic Drugs," Anesthesia Progress
59(4):159-169; Becker, D. E. 2011. "Adverse Drug Interactions,"
Anesthesia Progress 58(1):31-41; Bushra, R., Aslam, N., and Khan,
A. Y. 2011. "Food-drug Interactions," Oman Medical Journal
26(2):77-83; Hersh, E. V. and Giannakopoulos, H. 2010.
"Beta-adrenergic Blocking Agents and Dental Vasoconstrictors,"
Dental Clinics of North America 54(4):687-696; Centeno, R. F. and
Yu, Y. L. 2003. "The Propanolol-epinephrine Interaction Revisited:
A Serious and Potentially Catastrophic Adverse Drug Interaction in
Facial Plastic Surgery," Plastic and Reconstructive Surgery
111(2):944-945; Gandy, W. 1989. "Severe Epinephrine-propranolol
Interaction," [in Lithuanian with cursory abstract in English at
Pubmed], Annals of Emergency Medicine 18(1):98-99; Karl, H. W.,
Atlee, J. L. 3rd and Roberts, F. L. 1986. "Thiopental and
Epinephrine-induced Dysrhythmias in Dogs Anesthetized with
Enflurane or Isoflurane," Anesthesia and Analgesia 65(5):437-443;
Swedlow, D. B., Lee, K. W., and Downes, J. J. 1983.
"Epinephrine-halothane Interactions in Children," Anesthesiology
58(2):142-145; Sumikawa, K., Ishizaka, N., and Suzaki, M. 1983.
"Arrhythmogenic Plasma Levels of Epinephrine During Halothane,
Enflurane, and Pentobarbital Anesthesia in the Dog," Anesthesiology
58(4):322-325; Reisner, L. S. and Lippmann, M. 1975. "Ventricular
Arrhythmias after Epinephrine Injection in Enflurane and in
Halothane Anesthesia," Anesthesia and Analgesia 54(4):468-470;
British Medical Journal 1958. "DEATH after Adrenaline Injection,"
British Medical Journal 1(5072):716). Directly targeted rather than
introduced into the bloodstream by injection, infusion, or
inhalation, the drug passes through the body with negligible if any
distribution to tissue other than that at the treatment site,
significantly reducing if not eliminating adverse side effects.
[5064] Sensors can make it possible to identify incipient
indications of a concerning symptom at onset, in response to which
the automatic system can initiate the directly pipe-targeted
delivery of remedial medication to suppress or reverse the
condition before it becomes apparent to consciousness. In the case
of asthma, for example, when the patient is asleep with an
exacerbation burgeoning that would call for the use of an inhaler,
the automatic system would sense and respond to the incipient
mucous occlusion and inflammation, ideally, so early that the
episode might be averted while the patient continued to sleep. That
is, from its inchoate indications, the automatic system anticipates
an exacerbation and suppresses it before the patient would
otherwise use an inhaler or take medication. Contrariwise, the
system serves to dissuade an alert patient apprehensive about the
possibility of an imminent acute event from taking a potent drug
carrying the risk of adverse side effects needlessly, eliminating
the problem of `false alarms.`
[5065] With respect to any chronic component morbidity,
justification for implanting an automatically operated direct fluid
piping and/or wired electrostimulatory or thermal treatment system,
for example, are the relative degree of risk without it, the health
advantage in automatic monitoring and response, and the optimized
use of drugs in even ordinarily drug regimen noncompliant patients
by combining, when appropriate, a lower background dose with more
concentrated doses directly targeted to the nidi rather than
released into the general circulation. Drugs to treat asthma are
usually inspired; in which case an implanted channel of control is
not considered; however, where the patient is incapable of
self-care, drugs can be delivered to the lungs through ductus
side-entry jackets on the pulmonary arteries. Congenitally
anomalous or malformed anatomy and physical trauma of the bladder
surgically repairable, the gross anatomy when the implantation of
such a system is considered will be normal or postsurgical.
[5066] Assigned to the bladder, this arm or channel of control
detects the need for and regulates the release of drugs,
metabolites, hormones, enzymes, medicinal reagents, and/or delivers
electrostimulation through an electrode in the nonjacketing
connector directly into the wall or the cavity of the bladder, or
through a ductus jacket into the superior and/or inferior vesical
artery, electrostimulatory or chemical neuromodulation if
appropriate of the superior and/or hypogastric nerve and/or
inferior parasympathetic nerve fibers. To allow direct observation
if appropriate, the jacket or connector can incorporate miniature
cabled devices such as a fiber cystoscope or therapeutic device
such as a laser, the latter automatically actuated much as a drug
or drugs would be released.
[5067] Copending application Ser. No. 14/121,365 addresses
electrified round needle connector anchoring that allows
myostimulation and tungsten radiation shielding to allow the use of
low to moderate dose radioactive substances. Where nonlocal
metabolic factors such as hormonal or enzymatic are involved in the
bladder dysfunction, these are addressed through ductus side-entry
jackets or nonjacketing side-entry connectors local to this site or
these sites. Full implantation where the power requirement exceeds
that currently obtained from within the body, such as from an
arrangement employing miniature devices at the ankles to generate
power when the patient walks, used either immediately without
storage or battery-stored, necessitates a means of transmitting
energy transdermally, or transcutaneously.
[5068] This technology, especially beneficial when the patient for
any reason is not drug regimen compliant or unruly, is currently
undergoing considerable advancement (see, for example, Bocan, K.
N., Mickle, M. H., and Sejdic, E. 2017. "Tissue Variability and
Antennas for Power Transfer to Wireless Implantable Medical
Devices," Institute of Electrical and Electronics Engineers Journal
of Translational Engineering in Health and Medicine 5:2700111;
Agrawal, D. R., Tanabe, Y., Weng, D., Ma, A., Hsu, S., and 9 others
2017. "Conformal Phased Surfaces for Wireless Powering of
Bioelectronic Microdevices," Nature Biomedical Engineering 2017; 1.
pii: 0043 (in press); Tanabe, Y., Ho, J. S., Liu, J., Liao, S. Y.,
Zhen, Z., and 8 others 2017. "High-performance Wireless Powering
for Peripheral Nerve Neuromodulation Systems," Public Library of
Science One 12(10):e0186698; Mei, H., Thackston, K. A., Bercich, R.
A., Jefferys, J. G., and Irazoqui, P. P. 2017. "Cavity Resonator
Wireless Power Transfer System for Freely Moving Animal
Experiments," Institute of Electrical and Electronics Engineers
Transactions in Biomedical Engineering 64(4):775-785; Bocan, K. N.
and Sejdi , E. 2016. "Adaptive Transcutaneous Power Transfer to
Implantable Devices: A State of the Art Review," Sensors (Basel,
Switzerland) 16(3). pii: E393; Schormans, M., Valente, V., and
Demosthenous, A. 2016. "Frequency Splitting Analysis and
Compensation Method for Inductive Wireless Powering of Implantable
Biosensors," Sensors (Basel, Switzerland) 16(8). pii: E1229; Ahn,
D. and Ghovanloo, M. 2016. "Optimal Design of Wireless Power
Transmission Links for Millimeter-sized Biomedical Implants,"
Institute of Electrical and Electronics Engineers Transactions on
Biomedical Circuits and Systems 10(1):125-137; Ibrahim, A. and
Kiani, M. 2016. "A Figure-of-Merit for Design and Optimization of
Inductive Power Transmission Links for Millimeter-sized Biomedical
Implants," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Circuits and Systems 10(6):1100-1111;
Miao, M. and Kiani, M. 2016. "Optimal Resonance Configuration for
Ultrasonic Wireless Power Transmission to Millimeter-sized
Biomedical Implants," Conference Proceedings Institute of
Electrical and Electronics Engineers Engineering in Medicine and
Biology Society 2016:1934-1937; Ibrahim, A. and Kiani, M. 2016.
"Inductive Power Transmission to Millimeter-sized Biomedical
Implants Using Printed Spiral Coils," Conference Proceedings of the
Institute of Electrical and Electronics Engineers Engineering in
Medicine and Biology Society 2016:4800-4803; Gougheri, H. S. and
Kiani, M. 2016. "Optimal Frequency for Powering Millimeter-sized
Biomedical Implants Inside an Inductively-powered Homecage,"
Conference Proceedings of the Institute of Electrical and
Electronics Engineers Engineering in Medicine and Biology Society
2016:4804-4807; Ibrahim, A. and Kiani, M. 2015. "Safe Inductive
Power Transmission to Millimeter-sized Implantable Microelectronics
Devices," Conference Proceedings Institute of Electrical and
Electronics Engineers Engineering in Medicine and Biology Society
2015:32015:817-820; Zargham, M. and Gulak, P. G. 2015. "Fully
Integrated On-chip Coil in 0.13 .mu.m CMOS [complementary
metal-oxide-semiconductor] for Wireless Power Transfer Through
Biological Media," Institute of Electrical and Electronics
Engineers Transactions on Biomedical Circuits and Systems
9(2):259-271; Schormans, M., Valente, V., and Demosthenous, A.
2015. "Efficiency Optimization of Class-D Biomedical Inductive
Wireless Power Transfer Systems by Means of Frequency Adjustment,"
Conference Proceedings Institute of Electrical and Electronics
Engineers Engineering in Medicine and Biology Society
2015:5473-5476; Eom, K., Jeong, J., Lee, T. H., Lee, S. E., Jun, S.
B., and Kim, S. J. 2013. "Columnar Transmitter Based Wireless Power
Delivery System for Implantable Device in Freely Moving Animals,"
Conference Proceedings Institute of Electrical and Electronics
Engineers Engineering in Medicine and Biology Society
2013:1859-1862; Patel, S., Park, H., Bonato, P., Chan, L., and
Rodgers, M. 2012. "A Review of Wearable Sensors and Systems with
Application in Rehabilitation," Journal of Neuroengineering and
Rehabilitation 9:21).
[5069] Recent developments pertain to circuitry that combines
transdermal energy and data transfer (Mao, S., Wang, H., Zhu, C.,
Mao, Z. H., and Sun, M. 2017. "Simultaneous Wireless Power Transfer
and Data Communication Using Synchronous Pulse-controlled Load
Modulation," Measurement (London, England) 109:316-325, Op cit.;
Gong, C., Liu, D., Miao, Z., and Li, M. 2017. "A Magnetic-balanced
Inductive Link for the Simultaneous Uplink Data and Power
Telemetry," Sensors (Basel, Switzerland) 17(8). pii: E1768; Lee, J.
H., Sohn, I., and Kim, Y. H. 2017. "Simultaneous Wireless Power
Transfer and Secure Multicasting in Cooperative Decode-and-Forward
Relay Networks," Sensors (Basel, Switzerland) 17(5). pii: E1128;
Hu, H., Gao, Z., Liao, X., and Leung, V. C. M. 2017. "Secure
Communications in CIoT [Cognitive Internet of Things] Networks with
a Wireless Energy Harvesting Untrusted Relay," Sensors (Basel,
Switzerland) 17(9). pii: E2023; Jia, Y., Mirbozorgi, S. A., Wang,
Z., Hsu, C. C., Madsen, T. E., Rainnie, D., and Ghovanloo, M. 2017.
"Position and Orientation Insensitive Wireless Power Transmission
for EnerCage-Homecage System," Institute of Electrical and
Elecronics Engineers Transactions on Biomedical Engineering
64(10):2439-2449; Kiani, M. and Ghovanloo, M. 2015. "A 13.56-mbps
Pulse Delay Modulation Based Transceiver for Simultaneous
Near-field Data and Power Transmission," Institute of Electrical
and Electronics Engineers Transactions on Biomedical Circuits and
Systems 9(1):1-11; Boaventura, A. S. and Carvalho, N. B. 2015.
"Evaluation of Simultaneous Wireless Power Transfer and
Backscattering Data Communication Through Multisine Signals,"
Institute of Electrical and Electronics Engineers Wireless Power
Transfer Conference, at
http://ieeexplore.ieee.org/document/7139129/; Yang, D. X., Hu, Z.,
Zhao, H., Hu, H. F., Sun, Y. Z., Hou, B. J. 2015.
"Through-metal-wall Power Delivery and Data Transmission for
Enclosed Sensors: A Review," Sensors (Basel, Switzerland)
15(12):31581-31605; Lawry, T. J., Wilt, K. R., Ashdown, J. D.,
Scarton, H. A., and Saulnier, G. J. 2013. "A High-performance
Ultrasonic System for the Simultaneous Transmission of Data and
Power Through Solid Metal Barriers," Institute of Electrical and
Electronics Engineers Transactions on Ultrasonics, Ferroelectrics,
and Frequency Control 60(1):194-203; Ashdown, J., Wilt, K. R.,
Lawry, T. J., Saulnier, G. J., Shoudy, D. A., Scarton, H. A., and
Gavens, A. J. 2013. "A Full-duplex Ultrasonic Through-wall
Communication and Power Delivery System," Institute of Electrical
and Electronics Engineers Transactions on Ultrasonics,
Ferroelectrics, and Frequency Control 60(3):587-595; Young, D. J.
2009. "Wireless Powering and Data Telemetry for Biomedical
Implants," Institute of Electrical and Electronics Engineers
Engineering in Medicine and Biology Society Annual Conferece
Proceedings 2009:3221-3224, Op cit.).
[5070] As contemplated here, a body area, or body sensor, network
is primarily intended for implementation in an ambulatory
self-contained, self-sufficient, and if possible, fully implanted
medical management system to allow a microprocessor to direct the
targeted delivery of drugs and apply other therapeutic means
responsive to sensor inputs according to a prescription program.
With such a system, negative feedback allows the processor to
confirm the efficacy of treatment, so that dependency upon
clinicians in a remote clinic or medical center arises only if the
system malfunctions or the prescription program does not comprehend
an extreme condition.
[5071] The transmission problems encountered with long-range
biotelemetry from a body network as documented below whereby the
output of sensor implants is transmitted directly to the clinic do
not pertain to such a fully contained short-range system implanted
within a single patient. While a long range transceiver can be
implanted, it is likely to generate a level of heat that recommends
relegating it to an external pack, making it best avoided in favor
of self-contained medical management. Another option is to
interpose a secure cellular or satellite telephone or website to
pass sensor data to the clinic and allow the patient to communicate
with the medical staff.
[5072] That the system is entirely contained within or on the
patient means that a cardinal problem with body area networks not
circumscribed thus, internetwork interference and the
unpredictability of patient bodily movement as negatively affecting
network performance is avoided (Le, T. T. T. and Moh, S. 2017.
"Link Scheduling Algorithm with Interference Prediction for
Multiple Mobile WBANs [wireless body area networks]," Sensors
(Basel, Switzerland) 17(10). pii: E2231; Sahoo, P. K., Pattanaik,
S. R., and Wu, S. L. 2017. "A Reliable Data Transmission Model for
IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi
Interference," Sensors (Basel, Switzerland) 17(6). pii: E1320;
Sahoo, P. K., Pattanaik, S. R., and Wu, S. L. 2017. "Design and
Analysis of a Low Latency Deterministic Network MAC [medium access
control] for Wireless Sensor Networks," Sensors (Basel,
Switzerland) 17(10). pii: E2185; Sarkar, S. and Misra, S. 2016.
"From Micro to Nano: The Evolution of Wireless Sensor-Based Health
Care," Institute of Electrical and Electronics Engineers Pulse
7(1):21-25; Le, T. T. and Moh, S. 2016. "An Interference-aware
Traffic-priority-based Link Scheduling Algorithm for Interference
Mitigation in Multiple Wireless Body Area Networks," Sensors
(Basel, Switzerland) 16(12). pii: E2190; Kim, J. W., Barrado, J.
R., and Jeon, D. K. 2016. "Time and Energy Efficient Relay
Transmission for Multi-hop Wireless Sensor Networks," Sensors
(Basel, Switzerland) 16(7). pii: E985; Bhandari, S. and Moh, S.
2016. "A Priority-based Adaptive MAC [medium access control]
Protocol for Wireless Body Area Networks," Sensors (Basel,
Switzerland) 16(3). pii: E401). These are technical reasons for the
current inadequacy of non-self-contained systems, with nontechnical
problems of staff unavailability and automation failures awaiting
as equal if not greater problems. This lack of dependability is
further mentioned below.
[5073] While limited to the reporting of symptoms to medical
center-based diagnosticians rather than to a microprocessor
implanted within the patient to provide an immediate therapeutic
response, short-range Bluetooth ultra-low energy transception from
sensor implants or a wireless body area network (see, for example,
Cai, Z., Seyedi, M., Zhang, W., Rivet, F., and Lai, D. T. H. 2017.
"Characterization of Impulse Radio Intrabody Communication System
for Wireless Body Area Networks," Journal of Medical and Biological
Engineering 37(1):74-84; Rehan, W., Fischer, S., and Rehan, M.
2017. "A Critical Review of Surveys Emphasizing Routing in Wireless
Sensor Networks--An Anatomization under a General Survey Design
Framework," Sensors (Basel, Switzerland) 17(8). pii: E1713;
Rangarajan, A. 2016. "Emerging Trends in Healthcare Adoption of
Wireless Body Area Networks," Biomedical Instrumentation and
Technology 50(4):264-276; Effatparvar, M., Dehghan, M., and
Rahmani, A. M. 2016. "A Comprehensive Survey of Energy-aware
Routing Protocols in Wireless Body Area Sensor Networks," Journal
of Medical Systems 40(9):201; Movassaghi, S., Abolhasan, M.,
Lipman, J., Smith, D., and Jamalipour, A. 2014. "Wireless Body Area
Networks: A Survey," Institute of Electrical and Electronics
Engineers Communications Surveys and Tutorials; Seyedi, M., Kibret,
B., Lai, D. T., and Faulkner, M. 2013. "A Survey on Intrabody
Communications for Body Area Network Applications," Institute of
Electrical and Electronics Engineers Transactions on Biomedical
Engineering 60(8):2067-2079; Katsu, K., Anzai, D., and Wang, J.
2013. "System Development and Performance Evaluation on Detection
Schemes for UWB-IR [ultra wideband-impulse radio] Implant
Communications," Proceedings of the Institute of Electrical and
Electronics Engineers Engineering in Medicine and Biology Society
2013:1234-1237; Ullah, S., Higgins, H., Braem, B., Latre, B.,
Blondia, C., and 4 others 2012. "A Comprehensive Survey of Wireless
Body Area Networks: On PHY [physical], MAC [medium access control],
and Network Layers Solutions," Journal of Medical Systems
36(3):1065-1094; Custodio, V., Herrera, F. J., Lopez, G., and
Moreno, J. I. 2012. "A Review on Architectures and Communications
Technologies for Wearable Health-monitoring Systems," Sensors
(Basel, Switzerland) 12(10):13907-13946; Lin, W., Lei, S., Wei, C.,
Li, C., and Wang, C. 2012. "Advances in Sensor Node and Wireless
Communication Technology of Body Sensor Network," (in Chinese with
English abstract at Pubmed), Sheng Wu Yi Xue Gong Cheng Xue Za Zhi
[Journal of Biomedical Engineering] 29(3):568-573; Egbogah, E. E.
and Fapojuwo, A. O. 2011. "A Survey of System Architecture
Requirements for Health Care-based Wireless Sensor Networks,"
Sensors (Basel, Switzerland) 11(5):4875-4898; Bhattacharyya, D.,
Kim, T. H., and Pal, S. 2010. "A Comparative Study of Wireless
Sensor Networks and Their Routing Protocols," Sensors (Basel,
Switzerland) 10(12):10506-10523; van Halteren, A., Bults, R., Wac,
K., Dokovsky, N., Koprinkov, G., and 4 others 2004. "Wireless Body
Area Networks for Healthcare: The MobiHealth Project," Studies in
Health Technology and Informatics 108:181-193) to a proximate
cellular or satellite mobile telephone or internet terminal
provided it is secure, for long-range transmission and reception
eliminates the need to implant direct radio-based biotelemetric
circuitry.
[5074] However, human as well as electronic
communications-dependent, such an option is subject to much,
possibly critical, delay in response, with application of the
remedial measures decided dependent upon reaching a qualified
physician with access to such means (see, for example, Stone, J. A.
2017. "Mobile Medicine: Digital Dynamo or Virtual Vaporware,"
Canadian Journal of Cardiology 33(2):216-218; Balasingam, M.,
Ebrahim, J., and Ariffin, I. A. 2017. "Tele-echocardiography--Made
for Astronauts, Now in Hospitals," Indian Heart Journal
69(2):252-254; Shinbane, J. S. and Saxon, L. A. 2016. "Digital
Monitoring and Care: Virtual Medicine," Trends in Cardiovascular
Medicine 26(8):722-730; Mackintosh, N., Terblanche, M., Maharaj,
R., Xyrichis, A., Franklin, K., and 7 others 2016. "Telemedicine
with Clinical Decision Support for Critical Care: A Systematic
Review," Systematic Reviews 5(1):176; Venkataraman, R. and
Ramakrishnan, N. 2015. "Outcomes Related to Telemedicine in the
Intensive Care Unit: What We Know and Would Like to Know," Critical
Care Clinics 31(2):225-237; Subbarao, I. and Cooper, G. P. Jr.
2015. "Drone-based Telemedicine: A Brave but Necessary New World,"
Journal of the American Osteopathic Association 115(12):700-701;
Hao, J. F., Cui, H. M., Han, J. M., Bai, J. X., Song, X., and Cao,
N. 2014. "Tele-ICU: The Way Forward in Geriatric Care?," Aging
Clinical and Experimental Research 26(6):575-582; Ramnath, V. R.,
Ho, L., Maggio, L. A., and Khazeni, N. 2014. "Centralized
Monitoring and Virtual Consultant Models of Tele-ICU Care: A
Systematic Review," Telemedicine Journal and E-Health
20(10):936-961; Ramnath, V. R. and Khazeni, N. 2014. "Centralized
Monitoring and Virtual Consultant Models of Tele-ICU Care: A
Side-by-side Review," Telemedicine Journal and E-Health
20(10):962-971; Hsieh, J. C., Li, A. H., and Yang, C. C. 2013.
"Mobile, Cloud, and Big Data Computing: Contributions, Challenges,
and New Directions in Telecardiology," International Journal of
Environmental Research and Public Health 10(11):6131-6153; Zhang,
Y. and Xiao, H. 2009. "Bluetooth-based Sensor Networks for Remotely
Monitoring the Physiological Signals of a Patient," Institute of
Electrical and Electronics Engineers Transactions on Information
Technology in Biomedicine 13(6):1040-1048; Yousef, J. and Lars, A.
N. 2005. "Validation of a Real-time Wireless Telemedicine System
Using Bluetooth Protocol and a Mobile Phone for Remote Monitoring
Patient in Medical Practice," European Journal of Medical Research
10(6):254-262; Rasid, M. F. and Woodward, B. 2005. "Bluetooth
Telemedicine Processor for Multichannel Biomedical Signal
Transmission via Mobile Cellular Networks," Institute of Electrical
and Electronics Engineers Transactions on Information Technology in
Biomedicine 9(1):35-43). Compared to the implanted automatic and
self-sufficient system described herein, these means are
rudimentary and lacking in capability to respond promptly and
effectively.
[5075] XXI. Fully Implanted Ambulatory Adaptive Hierarchical
Control Systems for Automatic Response to a Comorbid Condition
[5076] While a form of artificial intelligence, as addressed
herein, adaptive and predictive hierarchical control is not an
example of conventional intelligent decision software-based medical
diagnostics, proposed therapy, or robotic surgery (see, for
example, Hamet, P. and Tremblay, J. 2017. "Artificial Intelligence
in Medicine," Metabolism: Clinical and Experimental 69S:S36-S40;
Ashrafian, H., Darzi, A., and Athanasiou, T. 2015. "A Novel
Modification of the Turing test for Artificial Intelligence and
Robotics in Healthcare," International Journal of Medical Robotics
and Computer Assisted Surgery 11(1):38-43; Bennett, C. C. and
Hauser, K. 2013. "Artificial Intelligence Framework for Simulating
Clinical Decision-making: A Markov Decision Process Approach,"
Artificial Intelligence in Medicine 57(1):9-19) as may eventually
be obtained with programs such as Microsoft Hanover, (Microsoft
Research 2016. "AI for Precision Medicine," at
http://hanover.azurewebsites.net/; Tung, L. 2016. "Microsoft's Next
Big AI Project? Helping `Solve` Cancer," at
http://www.zdnet.com/article/microsofts-next-big-ai-project-helping-solve-
-cancer/; Vincent, J. 2016. "Microsoft Announces New AI-powered
Health Care Initiatives Targeting Cancer," at
https://www.theverge.com/2016/9/20/12986314/microsoft-ai-healthcare-proje-
ct-hanover-cancer [[which seek to identify the optimal drugs for
the treatment of a diagnosed disease such as myeloid
leukemia]).
[5077] Rather, applied to interdependent morbidities in the present
context, an automatic disorder response system is used to evaluate
deviations from optimal physiological function, substance
concentrations, and imbalances in chemical processing activity. The
substances and processes chosen for monitoring each morbidity are
determined not on the basis of established syndromes whether
eponymous, but rather empirically, on the basis of initial
screening tests, several identified below, to identify the cause or
causes for the signs and symptoms, eliminating errors due to
symptom mimicry and any presuppositions of the medical staff. On
this basis, the sensors are placed, deviations from the normal
range noted, and drugs and doses appurtenant of each to return the
values of these physiological indicia to within the normal range
identified. The target organs and tissues, and agents to be used,
and whether these can be delivered through the same feedlines then
determine the detailed configuration and composition of the fluid
and electrical lines, jackets, and nonjacketing connectors, and
surface port if any to be used.
[5078] Significantly, such a system is self-corrective across
plural morbidities, the more important where the interactions among
these morbidities, especially those seldom seen in a single
patient, has not been established with any definitude. From this
standpoint, the system empirically sidesteps any misconceptions of
the attendings to contribute new information concerning the
interaction among such comorbidities. Additionally, because drug
delivery is piped and kept from entry into the circulation until
released at the treatment site, the action of each drug in relation
to each of the others is substantially isolated, allowing
qualitative and quantitative evaluation of the effect of each in
the context of the homeostatic condition of the patient.
[5079] In practice, for each of the component morbidities, a
sufficient number of implicated indicia are monitored, and each
sensor input is first evaluated in isolation, then in relation to
each of the others. A turret mechanism for taking different drugs
from a number of vials respective of each is described and
illustrated in copending application Ser. No. 14/121,365. Such a
system responds to the exact deficit of the problematic drug,
enzyme, or hormone, assuring proper dosage and in so doing, avoids
the risks of over- or under-dosage. In acting thus, the system acts
in effect as a backup, supplementary, or adjunct immune system for
deficient or missing analytes or metabolites.
[5080] In adapting spontaneously, the system is able to generate
the data needed to correct numerous inborn errors or congenital
defects of metabolism, that is, inherited or random mutation-based
congenital metabolic diseases (see, for example, Journal of Inborn
Errors of Metabolism and Screening 2017. "Abstracts presented at
the 13th International Congress of Inborn Errors of Metabolism,"
Journal of Inborn Errors of Metabolism and Screening, at
http://journals.sagepub.com/doi/full/10.1177/2326409817722292
[includes 919 ample abstracts]; Vernon, H. J. 2015. "Inborn Errors
of Metabolism: Advances in Diagnosis and Therapy," Journal of the
American Medical Association Pediatrics 169(8):778-782).
[5081] Such disorders, initially recognized clinically and
identified by means of screening tests using mass spectrometry, gas
chromatography-mass spectrometry, liquid ion-exchange
chromatography, quantification of amino acids in various body
fluids, ninhydrin paper chromatography, ferric chloride testing,
and less frequently, tissue biopsy or DNA testing, include numerous
defects of mitochondrial, carbohydrate, purine, pyrimidine,
porphyrin, lysosomal storage, and steroid function, among many
others. Most such disorders can be controlled through diet, enzyme
replacement, gene therapy, and organ transplantation. This
screening determines the type sensors to implant.
[5082] The initial identification of significant functions,
pathways, metabolites, and sensors needed must follow from standard
diagnostic tests. To avert misinterpretation and misdirection, more
than one diagnostician should always be consulted, and the impulse
to settle on a diagnosis before testing has been completed
suppressed. The results of this review are used to decide which
indicia should be pursued--with limiting presuppositions set aside.
If clear-cut, recognition of a syndrome is helpful; if ambiguous,
it may partially or entirely mislead. When the ascription of
symptoms is obscure or indefinite, sidestepping the nomenclature
and going straight to the physiological indicia serves to avert
errors. The direct detection of deviation from normal values of
physiological indicia does not apply to many conditions; however,
where it does, misdiagnoses can be prevented from the outset.
[5083] Where, however, the patient is too young, too old, or
incapacitated, or the regimen more involved, disorders managed
through enzyme replacement in particular are readily supported. If
the defective metabolite, usually an enzyme, is completely
ineffective, the response is to provide that metabolite, in which
case the delivery system is effectively `bionic.` If the metabolite
is partially ineffective or insufficient, the delivery system is
used to provide the missing fraction thereof. If the number of
drugs and/or size of each dose does not permit of implantation of
the reservoirs, typically subdermally in the pectoral region,
because these would intrude upon neighboring tissue, then the drug
turret switching mechanism is relegated to a belt-suspended power
and pump pack.
[5084] Alternatively, the pack can be worn about a thigh much as a
urine collection bag. Generally, only components that cannot be
comfortably implanted are relegated to an extracorporeal or worn
pack. When the overall condition of the patient is nonexigent as to
afford sufficient time, tissue expansion can be used to create the
space essential to achieve full implantation. Urgency and the
suitability of the patient to undergo implantation deciding
factors, when time is not available to accomplish more than sensor
or full implantation at the outset, or to accomplish the same with
tissue expansion, the process can proceed with the patient
temporarily provided with an external pack that includes only the
larger or more difficult components to place intracorporeally. If
necessary, the extracorporeal pack can include all but the sensors,
that is, the control, power, and pumps; in a decentralized or
distributed hierarchical control system, even lower level nodes can
transmit data to the external pack by wireless radio, addressed
below.
[5085] The response of the set to a drug is then gauged as to the
efficiency of which that drug affects the set. The adaptive system
`learns` which drug or combination thereof most closely restore the
patient to homeostatic equipoise. Such a reference model
architecture-based real-time control system emulates the nervous
system in vertebrates, in that sensory data assigned to every
location in the body is resolved locally by the immune and/or
endocrine systems, and the `data` streamed upward through the
spinal cord and bloodstream to the appropriate level or levels in
the brain, primarily the hypothalamus, this form of organization
with negative feedback reiterated at every level of the organism
from the cellular to the metabolic to the gross anatomic features
of the nervous and endocrine systems where the conditions at each
level educes complementary structure and function at every other
level.
[5086] Here, sites of different morbidity are each assigned a
channel of control which passes up through the hierarchical tree to
the master controller, while commands proceed from the master
controller down through the nodes of the tree to effectors, here
mostly small pumps at the outlets of small flat drug reservoirs
implanted subdermally in the pectoral region (see, for example,
Grasman, J., Callender, H. L., and Mensink, M. 2017. "Proportional
Insulin Infusion in Closed-Loop Control of Blood Glucose," Public
Library of Science One 12(1):e0169135; Scheidel, J., Lindauer, K.,
Ackermann, J., and Koch, I. 2015. "Quasi-Steady-state Analysis
Based on Structural Modules and Timed Petri Net Predict System's
Dynamics: The Life Cycle of the Insulin Receptor," Metabolites
5(4):766-793; Alcocer-Cuaron, C., Rivera, A. L., and Castano, V. M.
2014. "Hierarchical Structure of Biological Systems: A
Bioengineering Approach, Bioengineered 5(2):73-79; Vasil'ev, G. F.
2013. "Cybernetics and Biology," (in Russian with abstract in
English at Pubmed), Biofizika 58(4):732-736; Noble, D. 2012. "A
Theory of Biological Relativity: No Privileged Level of Causation,"
Interface Focus 2(1):55-64; Bortfeldt, R. H., Schuster, S., and
Koch, I. 2011. "Exhaustive Analysis of the Modular Structure of the
Spliceosomal Assembly Network: A Petri Net Approach," Studies in
Health Technology and Informatics 162:244-278; Gianchandani, E. P.,
Chavali, A. K., and Papin, J. A. 2010. "The Application of Flux
Balance Analysis in Systems Biology," Wiley Interdisciplinary
Reviews. Systems Biology and Medicine 2(3):372-382; Liu, W. and
Tang, F. 2008. "Modeling a Simplified Regulatory System of Blood
Glucose at Molecular Levels," Journal of Theoretical Biology
252(4):608-620; Grafahrend-Belau, E., Schreiber, F., Heiner, M.,
Sackmann, A., Junker, B. H., and 4 others 2008. "Modularization of
Biochemical Networks Based on Classification of Petri Net
T-invariants," BioMed Central Bioinformatics 9:90; Auffray, C. and
Nottale, L. 2008. "Scale Relativity Theory and Integrative Systems
Biology: 1. Founding Principles and Scale Laws," Progress in
Biophysics and Molecular Biology 97(1):79-114; Nottale, L. and
Auffray, C. 2008. "Scale Relativity Theory and Integrative Systems
Biology: 2. Macroscopic Quantum-type Mechanics," Progress in
Biophysics and Molecular Biology 97(1):115-157; Nederbragt, H.
1997. "Hierarchical Organization of Biological Systems and the
Structure of Adaptation in Evolution and Tumorigenesis," Journal of
Theoretical Biology 184(2): 149-156).
[5087] It is also analogous to the command and control tree of a
large organization, where orders pass down through subordinate
levels in the hierarchy and reports flow back up to the chief
executive officer. In practice, responsive measures are not limited
to the selection, dosing, and release or drugs but might include
the local application of warmth, chilling, or electrical
stimulation, for example. Moving up the control nodes, this process
is applied to each morbidity, then extended to include each of the
other morbidities, so that `aware` of all sensor inputs and
effector outputs for each drug or drugs tried across the set of
morbidities, for example, the master node is able to accumulate
`experience` as to gradually ascertain and apply the optimal
combination of responses to each component morbidity and therefore
the optimal combination of measures to apply in order to return the
set of morbidities to as normal a condition that the remedial
measures available, following any necessary surgery, will
allow.
[5088] The master node microprocessor continuously monitors the
homeostatic status of the patient, continuously adjusting the
release of drugs. In a hierarchically organized system of control,
each level in the hierarchy is situated along a vertically,
component morbidity-dedicated, and horizontally concomitant
morbidity-related node in an organizational tree. Since FIG. 108 is
drawn to reflect that the initial step is obtaining sensor data,
that is, drawn from the `sensory` rather than the `motor` view)
which then flows up through the tree, the command view which places
the master controller at the top and the tree as a whole appears as
inverted. Note that FIG. 108 shows effectors and control components
housed in an extracorporeal power and control pack, usually
suspended from a pants or skirt belt, suitable where the necessity
therefor is predicted to be not sufficiently long term to warrant
implantation, whereas FIG. 107, shows these components as
implanted.
[5089] For relative simplicity, FIG. 108 shows only three
hierarchical levels so that three levels of nodes are shown; the
upper two of the three modules--that implanted in the body shown in
the box at the top of the drawing--comprising the sensors and
effectors represent the lowest level, with the three levels
superior to these shown in the boxed about module at the bottom of
the drawing. Four sensors are assigned to each arm or channel of
control, with each set of four and the two intervening levels of
control or nodes assigned to either of the two morbidities present
and the master controller exercising control over the sum of
physiological indicia monitored. The need for sensors determined by
the condition to be monitored, the showing of four sensors to
monitor each of two component morbidities in FIG. 108 is arbitrary.
Since only serious chronic conditions warrant the placement of such
a system, for functioning sensors to be replaced or resituated
after initial placement is very unlikely.
[5090] The number of sensors required depends upon the least number
of physiological indicia or low level (initiative, foundational)
symptoms essential to adequately characterize the component
malfunction or morbidity, the complexity of control rising with the
addition of sensors and computational burden of coordinating these
inputs in the context of overall patient homeostasis, necessitating
the addition of hierarchical control levels, hence, nodes, and
increasing the power and heat generation of the master node
microprocessor. For this reason, a system assigned to monitor and
respond to several comorbid conditions, especially when these
interact, will likely necessitate an externally worn control,
power, and pump pack, both due to the number of components required
and the heat generated by the master node microprocessor and
perhaps the higher subordinate node microcontrollers.
[5091] As depicted in FIG. 108, sensory data responsive to the
antecedent remediating command, continuously flows up the tree from
subordinate to superior nodes, and commands adjusted on the basis
of this feedback are more precisely aligned to the overall tasks
and goals to be achieved, which continuously flow down the tree
from superior to subordinate nodes. Each node is thus both
semiautonomous but at the same time, responsive to the data flowing
up and down through it, with the penultimate level communicating
laterally as well. Broadly, the master node is a microprocessor and
the subordinate nodes microcontrollers.
[5092] The penultimate nodes, that is, those subordinate to the
master node, are assigned responsibility over each morbidity and
terminate in sensors and effectors responsive to their assigned
component morbidity. The tasks assigned to both sensors and
effectors at the lowest or immediate, local level are simplest and
take the least time to discharge, while each successively higher
level in the hierarchy is coordinative at a more encompassing
level. That is, each step up the hierarchical levels involves
greater and greater data correlation, integration, extraction, and
command input processing. For this reason, each higher level in the
tree requires somewhat more processing time than that just beneath
it.
[5093] In some instances, like data from multiple sensors is
combined " . . . to form a unified picture." (Khaleghi, B., Khamis,
A., and Karray, F. O., and Razavi, S. N. 2011. "Multisensor Data
Fusion: A Review of the State of the Art," Information Fusion
14(1):28-44; see also Liu, B., Zhan, X., and Zhu, Z. H. 2017.
"Multisensor Parallel Largest Ellipsoid Distributed Data Fusion
with Unknown Cross-Covariances," Sensors (Basel, Switzerland)
17(7). pii: E1526; Jain, K. 2017. "Use of Failure Mode Effect
Analysis (FMEA) to Improve Medication Management Process,"
International Journal of Health Care Quality Assurance
30(2):175-186; Jiang, W., Zhuang, M., and Xie, C. 2017. "A
Reliability-based Method to Sensor Data Fusion," Sensors (Basel,
Switzerland) 17(7). pii: E1575; Jain, K. 2017. "Use of Failure Mode
Effect Analysis (FMEA) to Improve Medication Management Process,"
International Journal of Health Care Quality Assurance
30(2):175-186; Deng X. and Jiang, W. 2017. "Fuzzy Risk Evaluation
in Failure Mode and Effects Analysis Using a D Numbers Based
Multi-Sensor Information Fusion Method," Sensors (Basel,
Switzerland) 17(9). pii: E2086; Bakr, M. A. and Lee, S. 2017.
"Distributed Multisensor Data Fusion under Unknown Correlation and
Data Inconsistency," Sensors (Basel, Switzerland) 17(11). pii:
E2472; Askari, R., Shafii, M., Rafiei, S., Abolhassani, M. S., and
Salarikhah, E. 2017. "Failure Mode and Effect Analysis: Improving
Intensive Care Unit Risk Management Processes," International
Journal of Health Care Quality Assurance 30(3):208-215; Pires, I.
M., Garcia, N. M., Pombo, N., and Florez-Revuelta, F. 2016. "From
Data Acquisition to Data Fusion: A Comprehensive Review and a
Roadmap for the Identification of Activities of Daily Living Using
Mobile Devices," Sensors (Basel, Switzerland) 16(2):184; Abdi, Z.,
Ravaghi, H., Abbasi, M., Delgoshaei, B., and Esfandiari, S. 2016.
"Application of Bow-tie Methodology to Improve Patient Safety,"
International Journal of Health Care Quality Assurance
29(4):425-440; Jiang, W., Xie, C., Zhuang, M., Shou, Y., and Tang,
Y. 2016. "Sensor Data Fusion with Z-Numbers and Its Application in
Fault Diagnosis," Sensors (Basel, Switzerland) 16(9). pii: E1509;
Klonoff, D. C. and Kerr, D. 2016. "Digital Diabetes Communication:
There's an App for That," Journal of Diabetes Science and
Technology 10(5):1003-1005; Shen, B., Liu, Y., Fu, J. S. 2014. "An
Integrated Model for Robust Multisensor Data Fusion," Sensors
(Basel, Switzerland) 14(10):19669-19686; Max Planck Institute for
Dynamics of Complex Technical Systems Magdeburg; 2017.
"Hierarchical Control Theory," at
http://www.mpi-magdeburg.mpg.de/95036/Hierarchical-Control-Theory;
"Hybrid Control Systems, at
http://www.mpi-magdeburg.mpg.de/90434/Hybrid-Control-Systems).
[5094] However, practically speaking, the data in most medical
applications require data extraction, fusion, and reduction with
the prediction of consequential ensuing direction through methods
such as Kalman and Kalman-derived filtering, or linear quadratic
estimation to trigger the release of drugs in anticipation of a
predictable tendency (see, for example, Su, J., Li, B., and Chen,
W.-H. 2015. "On Existence, Optimality and Asymptotic Stability of
the Kalman Filter with Partially Observed Inputs," Automatica 53:
149-154; Kalman, R. E. and Bucy, R. S. 1961. "New Results in Linear
Filtering and Prediction Theory," Transactions of the American
Society of Mechanical Engineers 83(D. Basic Engineering):95-108;
Kalman, R. E. 1960. "A New Approach to Linear Filtering and
Prediction Problems," Transactions of the American Society of
Mechanical Engineering 82(D. Basic Engineering):35-45), or Bayesian
inference only when numerous components are involved necessitating
summarization, such as a disorder resulting from deficiencies or
defects in cytochromes P450-containing enzymes in electron transfer
chain hemoproteins.
[5095] Since here the prescription program is not just intended to
optimize the treatment for each component morbidity but also to
return the patient to as healthy a status as can be achieved across
the entire complement or constellation of component morbidities,
the nodes subordinate to the master node exchange their data
laterally with the other nodes. This can be accomplished at the
subordinate nodes or the master controller node. Over time, the
master controller accumulates sufficient summary data concerning
the overall homeostatic status across the sum of sensor inputs of
the patient to infer the consequences of various possible responses
in the form of commands to be passed down through the tree to the
local effectors. It thus is able to dynamically adapt to the
combination of circumstances confronting it; that is, it
effectively `learns,` adapts, gradually tailoring its response
commands with greater and greater precision.
[5096] Such prescription programs are designed to first use
generalized data which pertains less than precisely to the disease
presented by the specific patient, and then by degrees where the
results of antecedent system results, adjust the detailed response
to achieve personalized, or `precision,` medicine (see, for
example, Sharafoddini, A., Dubin, J., and Lee, J. 2017. "Patient
Similarity in Prediction Models Based on Health Data: A Scoping
Review," Journal of Medical Internet Research Medical Informatics
5(1):e7; Schuck, R. N., Charlab, R., and Blumenthal, G. M. 2017.
"Leveraging Genomic Factors to Improve Benefit-Risk," Clinical and
Translational Science 10(2):78-83; Caraballo, P. J., Hodge, L. S.,
Bielinski, S. J., Stewart, A. K., Farrugia, G., and 11 others 2017.
"Multidisciplinary Model to Implement Pharmacogenomics at the Point
of Care," Genetics in Medicine 19(4):421-429; Cousin, M. A., Matey,
E. T., Blackburn, P. R., Boczek, N. J., McAllister, T. M., and 4
others 2017. "Pharmacogenomic Findings from Clinical Whole Exome
Sequencing of Diagnostic Odyssey Patients," Molecular Genetics and
Genomic Medicine 5(3):269-279; Hinderer, M., Boeker, M., Wagner, S.
A., Lablans, M., Newe, S., and 7 others 2017. "Integrating Clinical
Decision Support Systems for Pharmacogenomic Testing into Clinical
Routine--a Scoping Review of Designs of User-System Interactions in
Recent System Development," BioMed Central Medical Informatics and
Decision Making 17(1):81; Pacanowski, M. A. 2017. "Translating
Precision," Clinical and Translational Science 10(2):56-57;
Chakrabarti, S., Sen, A., Huser, V., Hruby, G. W., Rusanov, A.,
Albers, D. J., and Weng, C. 2017. "An Interoperable
Similarity-based Cohort Identification Method Using the OMOP
[Observational Medical Outcomes Partnership] Common Data Model
Version 5.0," Journal of Healthcare Informatics Research 1(1):1-18;
Ji, Y., Skierka, J. M., Blommel, J. H., Moore, B. E., VanCuyk, D.
L., and 14 others 2016. "Preemptive Pharmacogenomic Testing for
Precision Medicine: A Comprehensive Analysis of Five Actionable
Pharmacogenomic Genes Using Next-Generation DNA Sequencing and a
Customized CYP2D6 [cytochrome P450 2D6 enzyme, encoded by the
CYP2D6 gene important in the metabolizing of xenobiotics, such as
drugs and toxins] Genotyping Cascade," Journal of Molecular
Diagnostics 18(3):438-445; Al-Mozaini, M. A. and Mansour, M. K.
2016. "Personalized Medicine. Is It Time for Infectious Diseases?,"
Saudi Medical Journal 37(12):1309-1311; Brown, S. A. 2016. "Patient
Similarity: Emerging Concepts in Systems and Precision Medicine,"
Frontiers in Physiology 7:561; Formea, C. M., Nicholson, W. T., and
Vitek, C. R. 2015. "An Inter-professional Approach to Personalized
Medicine Education: One Institution's Experience," Personalized
Medicine 12(2):129-138; Agyeman, A. A. and Ofori-Asenso, R. 2015.
"Perspective: Does Personalized Medicine Hold the Future for
Medicine?," Journal of Pharmacy and Bioallied Sciences
7(3):239-244; Blaus, A., Madabushi, R., Pacanowski, M., Rose, M.,
Schuck, R. N., Stockbridge, N., Temple, R., and Unger, E. F. 2015.
"Personalized Cardiovascular Medicine Today: A Food and Drug
Administration/Center for Drug Evaluation and Research
Perspective," Circulation 132(15):1425-1432; Zhang, P., Wang, F.,
Hu, J., and Sorrentino, R. 2014. "Towards Personalized Medicine:
Leveraging Patient Similarity and Drug Similarity Analytics,"
American Medical Informatics Association Joint Summits on
Translational Science Proceedings 2014:132-136; Bielinski, S. J.,
Olson, J. E., Pathak, J., Weinshilboum, R. M., Wang, L., Lyke, K.
J., Ryu, E., and 28 others 2014. "Preemptive Genotyping for
Personalized Medicine: Design of the Right Drug, Right Dose, Right
Time-using Genomic Data to Individualize Treatment Protocol," Mayo
Clinic Proceedings 89(1):25-33; Kullo, I. J., Jarvik, G. P.,
Manolio, T. A., Williams, M. S., and Roden, D. M. 2013. "Leveraging
the Electronic Health Record to Implement Genomic Medicine,"
Genetics in Medicine 15(4):270-271).
[5097] Shortcomings for precision or personalized medicine should,
however, subside with experience in machine coordination of genomic
and integrated medical record data (see, for example, He, K. Y.,
Ge, D., and He, M. M. 2017. "Big Data Analytics for Genomic
Medicine," International Journal of Molecular Sciences 18(2). pii:
E412; Wu, P. Y., Cheng, C. W., Kaddi, C. D., Venugopalan, J.,
Hoffman, R., and Wang, M. D. 2017. "-Omic and Electronic Health
Record Big Data Analytics for Precision Medicine," Institute of
Electrical and Electronics Engineers Transaction on Biomedical
Engineering 64(2):263-273; Wu, P. Y., Cheng, C. W., Kaddi, C.,
Venugopalan, J., Hoffman, R., and Wang, M. D. 2016. "Advanced Big
Data Analytics for -Omic Data and Electronic Health Records: Toward
Precision Medicine," Institute of Electrical and Electronics
Engineers Transactions on Biomedical Engineering October (in
press); Carter, T. C. and He, M. M. 2016. "Challenges of
Identifying Clinically Actionable Genetic Variants for Precision
Medicine," Journal of Healthcare Engineering Article 3617572; He,
K. Y., Zhao, Y., McPherson, E. W., Li, Q., Xia, F., Weng, C., Wang,
K., and He, M. M. 2016. "Pathogenic Mutations in
Cancer-predisposing Genes: A Survey of 300 Patients with
Whole-genome Sequencing and Lifetime Electronic Health Records,"
Public Library of Science One 11(12):e0167847; Hovelson, D. H.,
McDaniel, A. S., Cani, A. K., Johnson, B., Rhodes, K., and 28
others 2015. "Development and Validation of a Scalable
Next-generation Sequencing System for Assessing Relevant Somatic
Variants in Solid Tumors," Neoplasia (NYC) 17(4):385-399; Zhang, L.
and Hong, H. 2015. "Genomic Discoveries and Personalized Medicine
in Neurological Diseases," Pharmaceutics 7(4):542-553; Ye, H.,
Meehan, J., Tong, W., and Hong, H. 2015. "Alignment of Short Reads:
A Crucial Step for Application of Next-Generation Sequencing Data
in Precision Medicine," Pharmaceutics 7(4):523-541; Dubchak, I.,
Balasubramanian, S., Wang, S., Cem, M., Sulakhe, D., and 15 others
2014. "An Integrative Computational Approach for Prioritization of
Genomic Variants," Public Library of Science One 9(12):e114903;
Chen, G. and Shi, T. 2013. "Next-generation Sequencing Technologies
for Personalized Medicine: Promising but Challenging," Science
China. Life Sciences 56(2):101-103; Hong, H., Zhang, W., Shen, J.,
Su, Z., Ning, B., Han, T., Perkins, R., Shi, L., and Tong, W. 2013.
"Critical Role of Bioinformatics in Translating Huge Amounts of
Next-generation Sequencing Data into Personalized Medicine,"
Science China. Life Sciences 56(2):110-118).
[5098] Adaptive and predictive real time hierarchical control as
pertains here uses a system of negative feedback loops with
electronics fully implanted for very long-term use, but relegated
to a belt-worn power and control pack for lesser periods, each
feedback loop sourced in one or more, usually several different
sensors assigned to an organ system or physiological pathway,
feeding data to the next higher hierarchical level, each level in
the hierarchy comparing and coordinating the data at that
hierarchical level, up to the highest level of the master
controller.
[5099] At that level, a prescription program under the control of
an implanted master microprocessor node directs the dispensing of
drugs to return the values read to within the normal range or
homeostatic set point empirically, without regard to semantic or
eponymous designation associated with the out-of-range readings as
a named syndrome, classification, or idiopathic condition,
especially since comorbidity can make the interrelation of symptoms
obscure, but not to a system that quantifies the component
physiological indicia without apportioning these among identified
disorders and evaluates the response of each and the set of indicia
as a whole to the drugs administered (see, for example, Mounce, L.
T. A., Price, S., Valderas, J. M., and Hamilton, W. 2017. "Comorbid
Conditions Delay Diagnosis of Colorectal Cancer: A Cohort Study
Using Electronic Primary Care Records," British Journal of Cancer
116(12):1536-1543; Cai, J., Yuan, Z., and Zhang, S. 2015.
"Abdominal Pain, Diarrhea, Constipation--Which Symptom is More
Indispensable to Have a Colonoscopy?," International Journal of
Clinical and Experimental Pathology 8(1):938-942; Eusebi, P. 2013.
"Diagnostic Accuracy Measures," Cerebrovascular Diseases (Basel,
Switzerland) 36(4):267-272; Pope, J. V. and Edlow, J. A. 2012.
"Avoiding Misdiagnosis in Patients with Neurological Emergencies,"
Emergency Medicine International 2012:949275; Adelstein, B. A.,
Macaskill, P., Chan, S. F., Katelaris, P. H., and Irwig, L. 2011.
"Most Bowel Cancer Symptoms Do Not Indicate Colorectal Cancer and
Polyps: A Systematic Review," BioMed Central Gastroenterology
11:65).
[5100] Eliminated are the impulses to classify the component
morbidities, the relationship between or among the diseases noted,
identify an index condition, or determine whether the comorbidities
subscribe to a more encompassing or common underlying disorder, for
example (see, for example, Valderas, J. M., Starfield, B., Sibbald,
B., Salisbury, C., and Roland, M. 2009. "Defining Comorbidity:
Implications for Understanding Health and Health Services," Annals
of Family Medicine 7(4):357-363; Rhee, S. H., Hewitt, J. K.,
Lessem, J. M., Stallings, M. C., Corley, R. P., and Neale, M. C.
2004. "The Validity of the Neale and Kendler Model-fitting Approach
in Examining the Etiology of Comorbidity," Behavior Genetics
34(3):251-265; Schellevis, F. G., van der Velden, J., van de
Lisdonk, E., van Eijk, J. T., and van Weel, C. 1993. "Comorbidity
of Chronic Diseases in General Practice," Journal of Clinical
Epidemiology 46(5):469-473).
[5101] In dealing with comorbidity of which one or more of the
component disorders are idiopathic and the number of possible
chemical deficiencies, excesses, and other out of range indicia
such as neuropsychological or endocrine malfunctions are too
numerous to allow implanting an equivalent number of sensors,
economic necessity mandates a reduction in this number by
withdrawing from the detailed to a summary level. In this
circumstance, the master node is provided with a library of
detailed chemical interrelations within the scope of each sensor
output as summary. By successive differential drug delivery as
moves the focus among the component interrelated chemical pathways,
the penultimate and master nodes gradually accumulate the data
essential to interpolate or infer the detailed causes and effects
comprehended within the sensor outputs.
[5102] At a higher level, the master node is entrusted with
inferring the sum of reactions among the sensors assigned to a
given component morbidity to have produced the summary result for
the component morbidity, and from there, the set of component
morbidities as a whole. For comorbidity of which each component
disorder is diagnosed and substantially noninteractive with each of
the others, the isolated targeting of drugs by direct piping avoids
drug-drug interactions and adverse side effects, to include
potential harm to uninvolved tissues and processes, while automated
release assures compliance in patients who are debilitated or
incompetent. From an economic standpoint, drug dispensing thus
significantly reduces the time and attendance to patients of clinic
or retirement community workers to occasional reservoir
replenishment.
[5103] The system passes lower level site specific sensor data to
the next higher level in the hierarchy and so on up through as many
higher coordinative levels as necessary to best approximate
homeostasis with the number of morbidities to be addressed (see,
for example, Yang, K. and Haibo, J. 2017. "Adaptive Hierarchical
Control for Output Feedback Systems," International Journal of
Control 90(11):2317-2325; Kulkarni, A. and Kumar, A. 2016.
"Adaptive Control Solution for a Class of MIMO
[multiinput/multioutput] Uncertain Underactuated Systems with
Saturating Inputs," International Journal of Intelligent Systems
and Application in Engineering 4(4):135-144; Meng, L. 2015.
Hierarchical Control for Optimal and Distributed Operation of
Microgrid Systems, Copenhagen, Denmark: Aalborg University Press.
Kulkarni, A. and Kumar, A. 2015. "Adaptive Hierarchical Control for
a Class of Uncertain Underactuated Systems with Actuator
Saturation," Journal of Electrical Engineering; Kulkarni, A. and
Kumar, A. 2014. "Adaptive Hierarchical Control for a Class of MIMO
[multiinput/multioutput] Uncertain Underactuated Systems,"
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Chella, A, and Goertzel, B. (eds) 2010. Biologically Inspired
Cognitive Architectures 2010: Proceedings of the First Annual
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Wheeled Mobile Robot," Institute of Electrical and Electronics
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id=2277586).
[5104] As an example of the advantages offered by direct piping and
release at the treatment site, few singular conditions, such as
incipient diabetes mellitus type 2 before it affects other
functions warrant directly targeted drug therapy through an
implanted piping system, much less an implanted system of automatic
control to react appropriately to a complex set of parameters;
properly dosed, cited is the biguanide-derivative antihyperglycemic
metformin hydrochloride oral, mostly marketed under the generic
trade name `Glucophage` from several makers. Some fraction of the
metformin dose must be delivered throughout the body but is
concentrated in the liver when a ductus side-entry jacket is used
to infuse the drug directly into the portal vein for first pass
delivery.
[5105] Where applicable, direct piping can avert the numerous
adverse side effects associated with metformin or any other drug or
reagent (see, for example, Wu, T, Horowitz, M., and Rayner, C. K.
2017. "New Insights into the Anti-diabetic Actions of Metformin:
From the Liver to the Gut," Expert Review of Gastroenterology and
Hepatology 11(2):157-166; Wang, Y., He, S. J., Feng, X., Cheng, J.,
Luo, Y. T., Tian, L., and Huang, Q. 2017. "Metformin: A Review of
Its Potential Indications," Drug Design, Development, and Therapy
11:2421-2429; Sanchez-Rangel, E. and Inzucchi, S. E. 2017.
"Metformin: Clinical Use in Type 2 Diabetes," Diabetologia August 2
(in press); Rena, G., Hardie, D. G., and Pearson, E. R. 2017. "The
Mechanisms of Action of Metformin," Diabetologia August 3 (in
press); Cameron, A. R., Logie, L., Patel, K., Erhardt, S., Bacon,
S., and 13 others 2017. "Metformin Selectively Targets Redox
Control of Complex I Energy Transduction," Redox Biology
14:187-197; Uddin, R., Nur-E-Habiba, Rena, G., Hwu, E. T., and
Boisen, A. 2017. "New Evidence for the Mechanism of Action of a
Type-2 Diabetes Drug Using a Magnetic Bead-based Automated
Biosensing Platform," American Chemical Society Sensors
2(9):1329-1336; An, H. and He L. 2016. "Current Understanding of
Metformin Effect on the Control of Hyperglycemia in Diabetes,"
Journal of Endocrinology 228(3):R97-106; Damiao, C. P., Rodrigues,
A. O., Pinheiro, M. F., Cruz Filho, R. A., Cardoso, G. P., Taboada,
G. F., and Lima, G. A. 2016. "Prevalence of Vitamin B12 Deficiency
in Type 2 Diabetic Patients Using Metformin: A Cross-sectional
Study," Sao Paulo Medical Journal June 3. pii:
S1516-31802016005004103 (in press); Zdilla, M. J. 2015. "Metformin
with Either Histamine H2-receptor Antagonists or Proton Pump
Inhibitors: A Polypharmacy Recipe for Neuropathy via Vitamin B12
Depletion," Clinical Diabetes 33(2):90-95 (also cited above under
Background of the Invention); McCreight, L. J., Bailey, C. J., and
Pearson, E. R. 2016. "Metformin and the Gastrointestinal Tract,"
Diabetologia 59(3):426-435; Pernicova, I. and Korbonits, M. 2014.
"Metformin--Mode of Action and Clinical Implications for Diabetes
and Cancer," Nature Reviews. Endocrinology 10(3):143-156;
Pernicova, I. and Korbonits, M. 2014. "Metformin--Mode of Action
and Clinical Implications for Diabetes and Cancer," Nature Reviews.
Endocrinology 10(3):143-156; Nasri, H. and Rafieian-Kopaei, M.
2014. "Metformin: Current Knowledge," Journal of Research in
Medical Sciences 19(7):658-664; Madiraju, A. K., Erion, D. M.,
Rahimi, Y., Zhang, X. M., and Braddock, D. T. 2014. "Metformin
Suppresses Gluconeogenesis by Inhibiting Mitochondrial
Glycerophosphate Dehydrogenase," Nature 510(7506):542-546; Viollet,
B. and Foretz, M. 2013. "Revisiting the Mechanisms of Metformin
Action in the Liver," Annales d' Endocrinologie (Paris, France)
74(2):123-129; Viollet, B., Guigas, B., Sanz Garcia, N., Leclerc,
J., Foretz, M., and Andreelli, F. 2012. "Cellular and Molecular
Mechanisms of Metformin: An Overview," Clinical Science (London,
England) 122(6):253-270; Isik, S., Ozcan, H. N., Ozuguz, U.,
Berker, D., Tutuncu, Y., Akbaba, G., and Guler, S. 2012. "Impaired
Gallbladder motility and the Effect of metformin Therapy in
patients with polycystic Ovary Syndrome," Clinical Endocrinology
(Oxford, England) 76(3):373-378) is of limited risk.
[5106] To treat diabetes, metformin must pass through the general
circulation in some dose to affect all tissues in any event, and is
known to favorably affect polycystic ovary syndrome and improve
fertility, the more so when combined with clomifene (see, for
example, Practice Committee of the American Society for
Reproductive Medicine with 20 collaborators 2017. "Role of
Metformin for Ovulation Induction in Infertile Patients with
Polycystic Ovary Syndrome (PCOS): A Guideline," Fertility and
Sterility 108(3):426-441; Clement, N. S., Oliver, T. R., Shiwani,
H., Sanner, J. R., Mulvaney, C. A., and Atiomo, W. 2017. "Metformin
for Endometrial Hyperplasia," Cochrane Database of Systematic
Reviews 10:CD012214; Nwanodi, O. 2017. "Progestin Intrauterine
Devices and Metformin: Endometrial Hyperplasia and Early Stage
Endometrial Cancer Medical Management," Healthcare (Basel,
Switzerland) 5(3). pii: E30; Al-Ruthia, Y. S., Al-Mandeel, H.,
AlSanawi, H., Mansy, W., AlGasem, R., and AlMutairi, L. 2017.
"Ovulation Induction by Metformin among Obese Versus Non-obese
Women with Polycystic Ovary Syndrome," Saudi Pharmaceutical Journal
25(5):795-800; Guo, Z., Sevrioukova, I. F., Denisov, I. G., Zhang,
X., Chiu, T. L., and 32 others 2017. "Heme Binding Biguanides
Target Cytochrome P450-Dependent Cancer Cell Mitochondria," Cell
Chemical Biology 24(10):1259-1275.e6; Ferreira, C., Sousa, M.,
Rabaca, A., Oliveira, P. F., Alves, M. G., and Sa, R. 2015. "Impact
of Metformin on Male Reproduction," Current Pharmaceutical Design
21(25):3621-3633; Naderpoor, N., Shorakae, S., de Courten, B.,
Misso, M. L., Moran, L. J., and Teede, H. J. 2015. "Metformin and
Lifestyle Modification in Polycystic Ovary Syndrome: Systematic
Review and Meta-analysis," Human Reproduction Update 21(5):560-574;
Alves, M. G., Martins, A. D., Vaz, C. V., Correia, S., Moreira, P.
I., Oliveira, P. F., and Socorro, S. 2014. "Metformin and Male
Reproduction: Effects on Sertoli Cell Metabolism," British Journal
of Pharmacology 171(4):1033-1042; Johnson, N. P. 2014. "Metformin
Use in Women with Polycystic Ovary Syndrome," Annals of
Translational Medicine 2(6):56; Lashen, H. 2010. "Role of Metformin
in the Management of Polycystic Ovary Syndrome," Therapeutic
Advances in Endocrinology and Metabolism 1(3): 117-128).
[5107] The benefits in direct tissue or organ nidus or lesion
targeting to avoid significant contact with unintended tissues and
organs apply to most drugs. For exemplary purposes, metformin is
addressed here because in the United States alone, it is prescribed
for about 65 million patients per year. While the literature is
frequently contradictory, mixing indications and contraindications,
especially where sleep disorders such as nighmares, insomnia,
sleepwalking, and sleep apnea are concerned, metformin can be said
to have beneficial effects for numerous diseases, and pending wider
confirmation, beneficial in man as well as lower vertebrates used
for testing as cited below. Some researchers claim that metformin
alleviates, while others claim it aggravates sleep disorders. It is
also claimed that metformin alleviates sleep apnea. Despite at
least 18 thousand published articles, numerous applications for
metformin, alone or combined with other drugs, remain indecisive
with trials ongoing (see, for example, Clement, N. S., Oliver, T.
R., Shiwani, H., Sanner, J. R., Mulvaney, C. A., and Atiomo, W.
2017. "Metformin for Endometrial Hyperplasia," Cochrane Database of
Systematic Reviews 10:CD012214).
[5108] Thus, widely prescribed and inordinately elusive of clear
characterization as either completely beneficial or deleterious,
references explicitly or implicitly pertaining to the sleep effects
of metformin are segregated here for citation (Petrie, J. R.,
Chaturvedi, N., Ford, I., Brouwers, M. C. G. J., and Greenlaw, N.,
11 others and 145 collaborators 2017. "Cardiovascular and Metabolic
Effects of Metformin in Patients with Type 1 Diabetes (REMOVAL)
[REducing with MetfOrmin Vascular Adverse Lesions in Type 1
Diabetes]: A Double-blind, Randomised, Placebo-controlled Trial,"
Lancet. Diabetes and Endocrinology 5(8):597-609; Schnell, O.,
Ryden, L., Standl, E., and Ceriello, A. 2017. "Updates on
Cardiovascular Outcome Trials in Diabetes," Cardiovascular
Diabetology 16(1):128; Elmaraezy, A., Abushouk, A. I., Emara, A.,
Elshahat, O., Ahmed, H., and I Mostafa, M. 2017. "Effect of
Metformin on Maternal and Neonatal Outcomes in Pregnant Obese
Non-diabetic Women: A Meta-analysis," International Journal of
Reproductive Biomedicine (Yazd, Iran) 15(8):461-470; So nicki, S.,
Kapral, M., and Wcglarz, L. 2016. "Molecular Targets of Metformin
Antitumor Action," Pharmacological Reports 68(5):918-925; Doumit,
J. and Prasad, B. 2016. "Sleep Apnea in Type 2 Diabetes," Diabetes
Spectrum 29(1):14-19; Lin, D., Rein, L., Tarima, S., Woodson, B.
T., and Meurer, J. R. 2015. "The Relationship Between Metformin and
Obstructive Sleep Apnea," Journal of Sleep Medicine and Disorders
2(4). pii: 1027; Wiernsperger, N. 2015. "Metformin as a Cellular
Protector: A Synoptic View of Modern Evidences," Journal of
Nephropharmacology 4(1):31-36. eCollection 2015; Priou, P., Le
Vaillant, M., Meslier, N., Chollet, S. 4, Pigeanne, T., 6 others,
and 15 collaborators 2015. "Association Between Obstructive Sleep
Apnea Severity and Gglucose Control in Patients with Untreated
Versus Treated Diabetes," Journal of Sleep Research 24(4):425-431;
Kajbaf, F., Fendri, S., Basille-Fantinato, A., Diouf, M., Rose, D.,
Jounieaux, V., and Lalau, J. D. 2014. "The Relationship Between
Metformin Therapy and Sleep Quantity and Quality in Patients with
Type 2 Diabetes Referred for Potential Sleep Disorders," Diabetic
Medicine 31(5):577-580; Inzucchi, S. E., Lipska, K. J., Mayo, H.,
Bailey, C. J., and McGuire, D. K. 2014. "Metformin in Patients with
Type 2 Diabetes and Kidney Disease: A Systematic Review," Journal
of the American Medical Association 312(24):2668-2675; Sivalingam,
V. N., Myers, J., Nicholas, S., Balen, A. H., and Crosbie, E. J.
2014. "Metformin in Reproductive Health, Pregnancy and
Gynaecological Cancer: Established and Emerging Indications," Human
Reproduction Update 20(6):853-868; El-Sharkawy, A. A.,
Abdelmotaleb, G. S., Aly, M. K., and Kabel, A. M. 2014. "Effect of
Metformin on Sleep Disorders in Adolescent Girls with Polycystic
Ovarian Syndrome," Journal of Pediatric and Adolescent Gynecology
27(6):347-352; Kajbaf, F., Fendri, S., Basille-Fantinato, A.,
Diouf, M., Rose, D., Jounieaux, V., and Lalau, J. D. 2014. "The
Relationship Between Metformin Therapy and Sleep Quantity and
Quality in Patients with Type 2 Diabetes Referred for Potential
Sleep Disorders," Diabetic Medicine 31(5):577-580; Grimaldi, D.,
Beccuti, G., Touma, C., Van Cauter, E., and Mokhlesi, B. 2014.
"Association of Obstructive Sleep Apnea in Rapid Eye Movement Sleep
with Reduced Glycemic Control in Type 2 Diabetes: Therapeutic
Implications," Diabetes Care 37(2):355-363; Shohrati, M.,
Karbasi-Afshar, R., and Saburi, A. 2012. "Remarks in Metformin and
Sleep Disorders in Diabetic Patients," Indian Journal of
Endocrinology and Metabolism 16(4):675-676; Wiwanitkit, S. and
Wiwanitkit, V. 2012. "Metformin and Sleep Disorders," Indian
Journal of Endocrinology and Metabolism 16 Supplement 1:S63-S64;
Ramadan, W., Petitjean, M., Loos, N., Geloen, A., Vardon, G.,
Delanaud, S., Gros, F., and Dewasmes, G. 2006. "Effect of High-fat
Diet and Metformin Treatment on Ventilation and Sleep Apnea in
Non-obese Rats," Respiration Physiology and Neurobiology
150(1):52-65).
[5109] Where potentially deleterious effects must be prevented and
the beneficial effect is local to the nidus, the clear indication
is to use direct piping to the treatment site through a ductus
side-entry jacket or nonjacketing side-entry connector. For
nondiabetic disease, directly piped targeting may open the way for
the preventive use of antidiabetic drugs in nondiabetics (see, for
example, Tseng, C. H. 2017. "Metformin is Associated with a Lower
Risk of Colorectal Cancer in Taiwanese Patients with Type 2
Diabetes: A Retrospective Cohort Analysis," Diabetes and Metabolism
43(5):438-445; Tseng, C. H. 2017. "Metformin and Lung Cancer Risk
in Patients with Type 2 Diabetes Mellitus," Oncotarget
8(25):41132-41142; Tseng, C. H. 2016. "Metformin Use and Cervical
Cancer Risk in Female Patients with Type 2 Diabetes," Oncotarget
7(37):59548-59555; Zhang, C. Y., Yuan, W. G., He, P., Lei, J. H.,
and Wang, C. X. 2016. "Liver Fibrosis and Hepatic Stellate Cells:
Etiology, Pathological Hallmarks and Therapeutic Targets," World
Journal of Gastroenterology 22(48):10512-10522). Use of metformin
in nondiabetic parturients, however, is contraindicated (Elmaraezy,
A., Abushouk, A. I., Emara, A., Elshahat, O., Ahmed, H., and I
Mostafa, M. 2017, cited below).
[5110] For nondiabetics, the potential applications of drugs
currently approved as antidiabetics for use by diabetics has been
found to affect a large number of other disorders related and
unrelated to insulin level (see, for example, Liang, Z., Li, T.,
Jiang, S., Xu, J., Di, W., Yang, Z., Hu, W., and Yang, Y. 2017.
AMPK [adenosine monophosphate-activated protein kinase]: A Novel
Target for Treating Hepatic Fibrosis," Oncotarget
8(37):62780-62792; Kim, H., Moon, S. Y., Kim, J. S., Baek, C. H.,
Kim, M., Min, J. Y., and Lee, S. K. 2015. "Activation of AMP
[adenosine monophosphate]--activated Protein Kinase Inhibits ER
[endoplasmic reticulum] Stress and Renal Fibrosis," American
Journal of Physiology. Renal Physiology 308(3):F226-F236; Ghosh, P.
2017. "The Stress Polarity Pathway: AMPK `GIV`-es [AMP-activated
protein kinase G-alpha interacting vesicle associated protein,
trade name Girdin] Protection Against Metabolic Insults," Aging
(Albany, N.Y.) 9(2):303-314; Li, X., Liu, R., Zhang, L., and Jiang,
Z. 2017. "The Emerging Role of AMP [adenosine
monophosphate]-activated Protein Kinase in Cholestatic Liver
Diseases," Pharmacological Research 125(Part B):105-113; Liao, K.
F., Chuang, H. Y., and Lai, S. W. 2017. "Metformin Use Correlates
with Reduced Risk of Gallstones in Diabetic Patients: A 12-Year
Follow-up Study," Frontiers in Pharmacology 8:765; Dasgupta, A.,
Trucco, M., Rainusso, N., Bernardi, R. J., Shuck, R., Kurenbekova,
L., Loeb, D. M., and Yustein, J. T. 2017. "Metabolic Modulation of
Ewing Sarcoma Cells Inhibits Tumor Growth and Stem Cell
Properties," Oncotarget 8(44):77292-77308; Wang, J., Zhu, L., Hu,
K, Tang, Y., Zeng, X., Liu, J., and Xu, J. 2017. "Effects of
Metformin Treatment on Serum Levels of C-reactive Protein and
Interleukin-6 in Women with Polycystic Ovary Syndrome: A
Meta-analysis: A PRISMA [preferred reporting items for systematic
reviews and meta-analyses]-compliant Article," Medicine (Baltimore,
Md.) 96(39):e8183; Udhane, S. S., Legeza, B., Marti, N., Hertig,
D., Diserens, G., Nuoffer, J. M., Vermathen, P., and Fluck, C. E.
2017. "Combined Transcriptome and Metabolome Analyses of Metformin
Effects Reveal Novel Links Between Metabolic Networks in
Steroidogenic Systems," Scientific Reports 7(1):8652; Horiuchi, T.,
Sakata, N., Narumi, Y., Kimura, T., Hayashi, T., and 8 others 2017.
"Metformin Directly Binds the Alarmin HMGB1 [high mobility group
box 1] and Inhibits Its Proinflammatory Activity," Journal of
Biological Chemistry 292(20):8436-8446; Imam, T. H. 2017. "Changes
in Metformin Use in Chronic Kidney Disease," Clinical Kidney
Journal 10(3):301-304.; Matsiukevich, D., Piraino, G., Lahni, P.,
Hake, P. W., Wolfe, V., O'Connor, M., James, J., and Zingarelli, B.
2017. "Metformin Ameliorates Gender- and Age-dependent Hemodynamic
Instability and Myocardial Injury in Murine Hemorrhagic Shock,"
Biochimica et Biophysica Acta 1863(10 Part B):2680-2691; Bell, S.,
Farran, B., McGurnaghan, S., McCrimmon, R. J., Leese, G. P., and 8
others 2017. "Risk of Acute Kidney Injury and Survival in Patients
Treated with Metformin: An Observational Cohort Study," BioMed
Central Nephrology 18(1):163; Tseng, C. H. 2017. "Metformin and
Lung Cancer Risk in Patients with Type 2 Diabetes Mellitus,"
Oncotarget 8(25):41132-41142; Yousef, M. and Tsiani, E. 2017.
"Metformin in Lung Cancer: Review of in Vitro and in Vivo Animal
Studies," Cancers (Basel, Switzerland) 9(5). pii: E45; Kim, P.,
Piraino, G., O'Connor, M., Hake, P. W., Wolfe, V., Lahni, P., and
Zingarelli, B. 2017. "Metformin Exerts Beneficial Effects in
Hemorrhagic Shock in an Ampk.alpha.1 [AMP-activated protein
kinase]-independent Manner," Shock September 14 (in press); Zhang,
S., Xu, H., Yu, X., Wu., Y., and Sui, D. 2017. "Metformin
Ameliorates Diabetic Nephropathy in a Rat Model of Low-dose
Streptozotocin-induced Diabetes," Experimental and Therapeutic
Medicine 14(1):383-390; Calip, G. S., Yu, O., Elmore, J. G., and
Boudreau, D. M. 2016. "Comparative Safety of Diabetes Medications
and Risk of Incident Invasive Breast Cancer: A Population-based
Cohort study," Cancer Causes and Control 27(5):709-720; Tseng, C.
H. 2016. "Metformin Reduces Gastric Cancer Risk in Patients with
Type 2 Diabetes Mellitus," Aging (Albany, N.Y.) 8(8):1636-1649; Du,
K., Ramachandran, A., Weemhoff, J. L., Chavan, H., Xie, Y.,
Krishnamurthy, P., and Jaeschke, H. 2016. "Editor's Highlight:
Metformin Protects Against Acetaminophen Hepatotoxicity by
Attenuation of Mitochondrial Oxidant Stress and Dysfunction,"
Toxicological Sciences 154(2):214-226; Singh, J., Olle, B., Suhail,
H., Felicella, M. M., and Giri, S. 2016. "Metformin-induced
Mitochondrial Function and ABCD2 Up-regulation in X-linked
Adrenoleukodystrophy Involves AMP-activated Protein Kinase,"
Journal of Neurochemistry 138(1):86-100; Chen, W., Liu, X., and Ye,
S. 2016. "Effects of Metformin on Blood and Urine Pro-inflammatory
Mediators in Patients with Type 2 Diabetes," Journal of
Inflammation (London, England) 13:34. eCollection 2016; Siskind, D.
J., Leung, J., Russell, A. W., Wysoczanski, D., and Kisely, S.
2016. "Metformin for Clozapine Associated Obesity: A Systematic
Review and Meta-Analysis," Public Library of Science One
11(6):e0156208; Sakoda, L. C., Ferrara, A., Achacoso, N. S., Peng,
T., Ehrlich, S. F., Quesenberry, C. P. Jr., and Habel, L. A. 2015.
"Metformin Use and Lung Cancer Risk in Patients with Diabetes,"
Cancer Prevention Research (Philadelphia, Pa.) 8(2):174-179; Kim,
Y. H., Hwang, J. H., Kim, K. S., Noh, J. R., Choi, D. H., and 5
others 2015. "Metformin Ameliorates Acetaminophen Hepatotoxicity
via Gadd45.beta.-dependent [growth arrest and DNA damage-inducible
45 beta protein-dependent] Regulation of JNK [c-Jun N-terminal
kinase] Signaling in Mice," Journal of Hepatology 63(1):75-82; Ryu,
R. J., Hays, K. E., and Hebert, M. F. 2014. "Gestational Diabetes
Mellitus Management with Oral Hypoglycemic Agents, Seminars in
Perinatology 38(8):508-515; Zhao, R. R., Xu, X. C., Xu, F., Zhang,
W. L., Zhang, W. L., Liu, L. M. 4, and Wang, W. P. 2014. "Metformin
Protects Against Seizures, Learning and Memory Impairments and
Oxidative Damage Induced by Pentylenetetrazole-induced Kindling in
Mice," Biochemical and Biophysical Research Communications 2014
448(4):414-417; Maruthini, D., Harris, S. E., Barth, J. H., Balen,
A. H., Campbell, B. K., and Picton, H. M. 2014. "The Effect of
Metformin Treatment in Vivo on Acute and Long-term Energy
Metabolism and Progesterone Production in Vitro by Granulosa Cells
from Women with Polycystic Ovary Syndrome," Human Reproduction
29(10):2302-2316; Nie, S. P., Chen, H., Zhuang, M. Q., and Lu, M.
2014. "Anti-diabetic Medications Do Not Influence Risk of Lung
Cancer in Patients with Diabetes Mellitus: A Systematic Review and
Meta-analysis," Asian Pacific Journal of Cancer Prevention
15(16):6863-6869; Luo, Q., Hu, D., Hu, S., Yan, M., Sun, Z., and
Chen, F. 2012. "In Vitro and in Vivo Anti-tumor Effect of Metformin
as a Novel Therapeutic Agent in Human Oral Squamous Cell
Carcinoma," BioMed Central Cancer 12:517; "Hirsch, A., Hahn, D.,
Kempna, P., Hofer, G., Nuoffer, J. M., Mullis, P. E., and Fluck, C.
E. 2012. "Metformin Inhibits Human Androgen Production by
Regulating Steroidogenic Enzymes HSD3B2 and CYP17A1 and Complex I
Activity of the Respiratory Chain," Endocrinology 153(9):4354-4366;
Lai, S. W., Bjorkhem-Bergman, L., Asplund, A. B., and Lindh, J. D.
2011. "Metformin for Weight Reduction in Non-diabetic Patients on
Antipsychotic Drugs: A Systematic Review and Meta-analysis,"
Journal of Psychopharmacology (Oxford, England) 25(3):299-305; Muo,
C. H., Liao, K. F., Sung, F. C., and Chen, P. C. 2011. "Risk of
Acute Pancreatitis in Type 2 Diabetes and Risk Reduction on
Anti-diabetic Drugs: A Population-based Cohort Study in Taiwan,"
American Journal of Gastroenterology 106(9):1697-1704;
Gonzalez-Perez, A., Schlienger, R. G., and Rodriguez, L. A. 2010.
"Acute Pancreatitis in Association with type 2 Diabetes and
Antidiabetic Drugs: A Population-based Cohort Study," Diabetes Care
33(12):2580-2585).
[5111] By the same token, emplacing a directly pipe-targeting
system with downstream reversal or neutralization if necessary can
make possible the freer use of metformin in patients in whom solely
systemic dispersal would otherwise provoke adverse reactions,
questionably, as documented below, in those with kidney, liver, and
lung disease, but also in those without such preconditions made
nauseous, diarrheic, rarely, lactic acidotic, and according to some
but disputed by others who, directly contradictory, ascribe to
metformin a protective role, impaired mental function more
pronounced than that attributable to diabetes alone, in the elderly
partially reversible with the administration of vitamin B.sub.12,
(cobalmin), (Bornstein, S., Moschetta, M., Kawano, Y., Sacco, A.,
Huynh, D., and 12 others 2017. "Metformin Affects Cortical Bone
Mass and Marrow Adiposity in Diet-induced Obesity in Male Mice,"
Endocrinology 158(10):3369-3385; Herath, P. M., Cherbuin, N.,
Eramudugolla, R., and Anstey, K. J. 2016. "The Effect of Diabetes
Medication on Cognitive Function: Evidence from the PATH
[population-based cohort study in Australia] Through Life Study,"
Biomed Research International 2016:7208429; Cholerton, B., Baker,
L. D., Montine, T. J., and Craft, S. 2016. "Type 2 Diabetes,
Cognition, and Dementia in Older Adults: Toward a Precision Health
Approach," Diabetes Spectrum 29(4):210-219; Hemmingsen, B., Sonne,
D. P., Metzendorf, M. I., and Richter, B. 2016. "Insulin
Secretagogues for Prevention or Delay of Type 2 Diabetes Mellitus
and Its Associated Complications in Persons at Increased Risk for
the Development of type 2 Diabetes Mellitus," Cochrane Database of
Systematic Reviews 10:CD012151; Feinkohl, I., Price, J. F.,
Strachan, M. W., and Frier, B. M. 2015. "The Impact of Diabetes on
Cognitive Decline: Potential Vascular, Metabolic, and Psychosocial
Risk Factors," Alzheimer's Research and Therapy 7(1):46; Guo, M.,
Mi, J., Jiang, Q. M., Xu, J. M., Tang, Y. Y., Tian, G., and Wang,
B. 2014. "Metformin May Produce Antidepressant Effects Through
Improvement of Cognitive Function Among Depressed Patients with
Diabetes Mellitus," Clinical and Experimental Pharmacology and
Physiology 41(9):650-656; Ng, T. P., Feng, L., Yap, K. B., Lee, T.
S., Tan, C. H., and Winblad, B. 2014. "Long-term Metformin Usage
and Cognitive Function Among Older Adults with Diabetes," Journal
of Alzheimer's Disease 41(1):61-68; Moore, E. M., Mander, A. G.,
Ames, D., Kotowicz, M. A., Came, R. P., 10 others, and 150
collaborators 2013. "Increased Risk of Cognitive Impairment in
Patients with Diabetes is Associated with Metformin," Diabetes Care
36(10):2981-2987; Chapman, L. E., Darling, A. L., and Brown, J. E.
2016, cited below; Ahmed, M. A. 2016, cited below; Saedi, E.,
Gheini, M. R., Faiz, F., and Arami, M. A. 2016. "Diabetes Mellitus
and Cognitive Impairments," World Journal of Diabetes
7(17):412-422), in the elderly, administered parenterally or in the
form of sublingual micro-lozenges for absorption through the oral
mucosa (but see Zhao, R. R., Xu, X. C., Xu, F., Zhang, W. L.,
Zhang, W. L., Liu, L. M. 4, and Wang, W. P. 2014, cited above),
where the bulk of the dose is directly targeted in a higher
concentration with a reduced dose if necessary infused into the
general circulation through a ductus side-entry jacket about the
portal vein, for example, (see, for example, Thangthaeng, N.,
Rutledge, M., Wong, J. M., Vann, P. H., Forster, M. J., and Sumien,
N. 2017. "Metformin Impairs Spatial Memory and Visual Acuity in Old
Male Mice," Aging and Disease 8(1):17-30; Khan, A., Shafiq, I., and
Hassan Shah, M. 2017. "Prevalence of Vitamin B12 Deficiency in
Patients with Type II Diabetes Mellitus on Metformin: A Study from
Khyber Pakhtunkhwa," Cureus 9(8):e1577; Camilleri, M., Malhi, H.,
and Acosta, A. 2017. "Gastrointestinal Complications of Obesity,"
Gastroenterology 152(7):1656-1670; Weinrauch, L. A., Segal, A. R.,
Bayliss, G. P., Liu, J., Wisniewski, E., and D'Elia, J. A. 2017.
"Changes in Treatment of Hyperglycemia in a Hypertensive Type 2
Diabetes Population as Renal Function Declines," Clinical Kidney
Journal 10(5):661-665; Bicsak, T. A., Walsh, B., and Fineman M.
2017. "Metformin-associated Lactic Acidosis: Moving Towards a New
Paradigm?," Diabetes, Obesity, and Metabolism 19(11):1499-1501;
Gangopadhyay, K. K. and Singh, P. 2017. "Consensus Statement on
Dose Modifications of Antidiabetic Agents in Patients with Hepatic
Impairment," Indian Journal of Endocrinology and Metabolism
21(2):341-354; Lalau, J. D., Kajbaf, F., Protti, A., Christensen,
M. M., De Broe, M. E., and Wiernsperger, N. 2017.
"Metformin-associated Lactic Acidosis (MALA): Moving Towards a New
Paradigm," Diabetes, Obesity, and Metabolism 19(11):1502-1512;
Yang, J. S., Lu, C. C., Kuo, S. C., Hsu, Y. M., Tsai, S. C., and 11
others 2017. "Autophagy and Its Link to Type II Diabetes Mellitus,"
Biomedicine (Taipei, Taiwan) 7(2):8; Siavash, M., Tabbakhian, M.,
Sabzghabaee, A. M., and Razavi, N. 2017. "Severity of
Gastrointestinal Side Effects of Metformin Tablet Compared to
Metformin Capsule in Type 2 Diabetes Mellitus Patients," Journal of
Research in Pharmaceutical Practice 6(2):73-76; Bonnet, F. and
Scheen, A. 2017. "Understanding and Overcoming Metformin
Gastrointestinal Intolerance," Diabetes, Obesity, and Metabolism
19(4):473-481; Abdelgadir, E., Ali, R., Rashid, F., and Bashier, A.
2017. "Effect of Metformin on Different Non-diabetes Related
Conditions, a Special Focus on Malignant Conditions: Review of
Literature," Journal of Clinical Medicine Research 9(5):388-395;
Connelly, P. J., Lonergan, M., Soto-Pedre, E., Donnelly, L., Zhou,
K., and Pearson, E. R. 2017. "Acute Kidney Injury, Plasma Lactate
Concentrations and Lactic Acidosis in Metformin Users: A GoDarts
[Genetics of Diabetes Audit and Research Tayside cohort] Study,"
Diabetes, Obesity, and Metabolism 19(11):1579-1586; Lo, C., Jun,
M., Badve, S. V., Pilmore, H., White, S. L., and 4 others 2017.
"Glucose-lowering Agents for Treating Pre-existing and New-onset
Diabetes in Kidney Transplant Recipients," Cochrane Database of
Systematic Reviews 2:CD009966; McCreight, L. J., Bailey, C. J., and
Pearson, E. R. 2016. "Metformin and the Gastrointestinal Tract,"
Diabetologia 59(3):426-435; Chapman, L. E., Darling, A. L., and
Brown, J. E. 2016. "Association Between Metformin and Vitamin B12
Deficiency in Patients with Type 2 Diabetes: A systematic Review
and Meta-analysis," Diabetes and Metabolism 42(5):316-327; Ahmed,
M. A. 2016. "Metformin and Vitamin B12 Deficiency: Where Do We
Stand?," Journal of Pharmacy and Pharmaceutical Sciences
19(3):382-398; Vos, R. C., van Avendonk, M. J., Jansen, H.,
Goudswaard, A. N., van den Donk, M., Gorter, K., Kerssen, A., and
Rutten, G. E. 2016. "Insulin Monotherapy Compared with the Addition
of Oral Glucose-lowering Agents to Insulin for People with Type 2
Diabetes Already on Insulin Therapy and Inadequate Glycaemic
Control," Cochrane Database of Systematic Reviews 9:CD006992;
Sakoda, L. C., Ferrara, A., Achacoso, N. S., Peng, T., Ehrlich, S.
F., Quesenberry, C. P. Jr., and Habel, L. A. 2015. "Metformin Use
and Lung Cancer Risk in Patients with Diabetes," Cancer Prevention
Research (Philadelphia, Pa.) 2015 8(2):174-179; Lalau, J. D.,
Arnouts, P., Sharif, A., and De Broe, M. E. 2015. "Metformin and
Other Antidiabetic Agents in Renal Failure Patients," Kidney
International 87(2):308-322; i, L., Zinman, B., Patel, S., Ji, J.,
Bailes, Z., Thiemann, S., and Seck, T. 2015. "Efficacy and Safety
of Linagliptin Co-administered with Low-dose Metformin Once Daily
Versus High-dose Metformin Twice Daily in Treatment-naive Patients
with Type 2 Diabetes: A Double-blind Randomized Trial," Advances in
Therapy 32(3):201-215; Heaf, J. 2014. "Metformin in Chronic Kidney
Disease: Time for a Rethink," Peritoneal Dialysis International
34(4):353-357; Rocha, A., Almeida, M., Santos, J., and Carvalho, A.
2013. "Metformin in Patients with Chronic Kidney Disease: Strengths
and Weaknesses," Journal of Nephrology 26(1):55-60; Saadi, T.,
Waterman, M., Yassin, H., and Baruch, Y. 2013. "Metformin-induced
Mixed Hepatocellular and Cholestatic Hepatic Injury: Case Report
and Literature Review," International Journal of General Medicine
6:703-706; Alsubaie, S. and Almalki, M. H. 2013. "Metformin Induced
Acute Pancreatitis," Dermatoendocrinology 5(2):317-318; Boland, B.
S., Edelman, S. V., and Wolosin, J. D. 2013. "Gastrointestinal
Complications of Diabetes," Endocrinology and Metabolic Clinics of
North America 42(4):809-83; Rafieian-Kopaie, M. 2013. "Metformin
and Renal Injury Protection," Journal of Renal Injury Prevention
2(3):91-92; Bouchoucha, M., Uzzan, B., and Cohen, R. 2011.
"Metformin and Digestive Disorders," Diabetes and Metabolism
37(2):90-96; Brackett, C. C. 2010. "Clarifying Metformin's Role and
Risks in Liver Dysfunction," Journal of the American Pharmacists
Association (2003) 50(3):407-410; Decensi, A., Puntoni, M.,
Goodwin, P., Cazzaniga, M., Gennari, A., Bonanni, B., and Gandini,
S. 2010. "Metformin and Cancer Risk in Diabetic Patients: A
Systematic Review and Meta-analysis," Cancer Prevention Research
(Philadelphia, Pa.) 3(11):1451-1461; Hoffmann, I. S., Roa, M.,
Torrico, F., and Cubeddu, L. X. 2003. "Ondansetron and
Metformin-induced Gastrointestinal Side Effects," American Journal
of Therapeutics 10(6):447-451). Such a system is also beneficial
where concentrated doses to target sites allow the systemic dose to
be much reduced. That view that metformin is contraindicated in
patients with chronic kidney disease is currently undergoing
transition.
[5112] Other drugs for the treatment of Type 2 diabetes, such as
the glucagon-like peptide 1 receptor agonist dipeptidyl peptidase-4
(DPP-4) inhibitors sitagliptin (Januvia.RTM., Merck), liraglutide
(Victoza.RTM., Saxenda.RTM. Novo Nordisk), exenatide (Byetta.RTM.,
Bydureon.RTM. AstraZeneca), dulaglutide (Trulicity.RTM., Eli Lilly
and Company), and the newer semaglutide (Ozempic.RTM., Novo
Nordisk), as almost all drugs can produce adverse side effects that
would be substantially reduced if not indiscriminately dispersed at
the effective dose throughout the body rather than differentially
delivered to target tissue, to include kidney and pancreatic
damage, and equivocally, thyroid cancer.
[5113] This includes semaglutide, effective for its intended
purposes, and possibly preferable for heart patients (see, for
example, Cosmi, F., Laini, R., and Nicolucci, A. 2017. "Semaglutide
and Cardiovascular Outcomes in Patients with Type 2 Diabetes," New
England Journal of Medicine 376(9):890; Ipp, E., Genter, P., and
Childress, K. 2017. "Semaglutide and Cardiovascular Outcomes in
Patients with Type 2 Diabetes," New England Journal of Medicine
376(9):890-891; Williams, T. C. and Stewart, E. 2017. "Semaglutide
and Cardiovascular Outcomes in Patients with Type 2 Diabetes," New
England Journal of Medicine 376(9):891; Marso, S. P., Holst, A. G.,
and Vilsboll, T. 2017. "Semaglutide and Cardiovascular Outcomes in
Patients with Type 2 Diabetes," New England Journal of Medicine
376(9):891-892; Marso, S. P., Bain, S. C., Consoli, A.,
Eliaschewitz, F. G., Jodar, E., and 10 others 2016. "Semaglutide
and Cardiovascular Outcomes in Patients with Type 2 Diabetes," New
England Journal of Medicine 375(19):1834-1844); but not free of
adverse side effects, such as gastrointestinal (see, for example,
Htike, Z. Z., Zaccardi, F., Papamargaritis, D., Webb, D. R.,
Khunti, K., and Davies M. J. 2017. "Efficacy and Safety of
Glucagon-like Peptide-1 Receptor Agonists in Type 2 Diabetes: A
Systematic Review and Mixed-Treatment Comparison Analysis,"
Diabetes, Obesity, and Metabolism 19(4):524-536; Tan, X., Cao, X.,
Zhou, M., Zou, P., and Hu, J. 2017. "Efficacy and Safety of
Once-weekly Semaglutide for the Treatment of Type 2 Diabetes,"
Expert Opinion on Investigational Drugs 26(9):1083-1089; Xue, X.,
Ren, Z., Zhang, A., Yang, Q., Zhang, W., and Liu, F. 2016.
"Efficacy and Safety of Once-weekly Glucagon-like Peptide-1
Receptor Agonists Compared with Exenatide and Liraglutide in Type 2
Diabetes: A Systemic Review of Randomised Controlled Trials,"
Internatonal Journal of Clinical Practice 70(8):649-656; Nauck, M.
A., Petrie, J. R., Sesti, G., Mannucci, E., Courreges, J. P.,
Lindegaard, M. L., Jensen, C. B., and Atkin, S. L. 2016. "A Phase
2, Randomized, Dose-Finding Study of the Novel Once-Weekly Human
GLP-1 Analog, Semaglutide, Compared with Placebo and Open-label
Liraglutide in Patients with Type 2 Diabetes," Diabetes Care
39(2):231-241).
[5114] However, exceptions pertain to immunosuppressive,
anti-inflammatory, antimicrobial, and anticancer drugs which bode
significant side effects for unintended tissue, and therefore serve
better when targeted. The applications contemplated pertain to
comorbidity, where either substantially independent or
noninteractive morbidities coexist or interdependent disease
conditions associated with one or more organs, tissues, and/or
chemical pathways interact in so complex a manner as to warrant
automated computation to define or characterize and control the
targeted delivery of drugs to various loci to best achieve optimal
health given the overall condition of the patient.
[5115] The long term use of steroids without isolation from
nontargeted tissue by directly piped delivery to the nidus or site
of treatment can create the opportunity for infection, produce or
aggravate a morbidity or comorbidity, such as chronic airway
congestive conditions addressed above, or when used to ameliorate
inflammation in solid organ transplantation where systemic
immunosuppressants cooperate to render the patient especially
susceptible to infection, and can provoke serious endocrine,
musculoskeletal, central nervous system, and cardiovascular effects
(see, for example, Malvezzi, P., Jouve, T., and Rostaing, L. 2017.
"Long-Term Steroid-Based Therapy: Risk of Infectious Complications
in Immunosuppressed Kidney-Transplant Recipients as Compared to the
General Population," Journal of Urology & Nephrology 2(
)2:000124; Chaudhary, N. S. 2, Donnelly, J. P. 2, Moore, J. X.,
Baddley, J. W., Safford, M. M., and Wang, H. E. 2017. "Association
of Baseline Steroid Use with Long-term Rates of Infection and
Sepsis in the REGARDS [reasons for geographic and racial
differences in stroke] Cohort," Critical Care (London, England)
21(1):185; Dalal, A. A., Duh, M. S., Gozalo, L., Robitaille, M. N.,
Albers, F., and 5 others 2016. "Dose-Response Relationship Between
Long-term Systemic Corticosteroid Use and Related Complications in
Patients with Severe Asthma," Journal of Managed Care and Specialty
Pharmacy 22(7):833-847; Rostaing, L. and Malvezzi, P. 2016.
"Steroid-based Therapy and Risk of Infectious Complications,"
Public Library of Science Medicine 13(5):e1002025; Youssef, J.,
Novosad, S. A., and Winthrop, K. L. 2016. "Infection Risk and
Safety of Corticosteroid Use," Rheumatic Diseases Clinics of North
America 42(1):157-176, ix-x; Lefebvre, P., Duh, M. S., Lafeuille,
M. H., Gozalo, L., Desai, U., and 7 others 2015. "Acute and Chronic
Systemic Corticosteroid-related Complications in Patients with
Severe Asthma," Journal of Allergy and Clinical Immunology
136(6):1488-1495; Cukuranovic, J., Ugrenovic, S., Jovanovic, I.,
Visnjic, M., and Stefanovic, V. 2012. "Viral Infection in Renal
Transplant Recipients," Scientific World Journal 2012:820621;
Moghadam-Kia, S. and Werth, V. P. 2010. "Prevention and Treatment
of Systemic Glucocorticoid Side Effects," International Journal of
Dermatology 49(3):239-248).
[5116] Hundreds of such examples might be adduced, to include the
use of corticosteroids to ameliorate the symptoms of inflammatory
bowel disease. Delivery to the lungs of a corticosteroid is
generally through ductus side-entry jackets on the pulmonary
arteries. Rather, the applications for a fully implanted
hierarchical drug dispensing control system contemplated pertain to
comorbidity, where either substantially independent morbidity
exists or interdependent diseased conditions of one or more organs,
tissues, and/or chemical pathways interact. FIG. 107 shows the use
of a nonjacketing side-entry connector to channel drugs directly
into the bladder wall and/or cavity. An antibiotic destructive to
the intestinal microbiota is eliminated from the gut. At the gut, a
corticosteroid used to reduce the inflammation of an inflammatory
bowel disease is kept from steroid-susceptible tissues and those
the steroid renders susceptible to infection.
[5117] Then the object is to return each loop and substrate pathway
to its normal set point, and in so doing, remediate the totality of
malfunction in its interactive consequences. In complex situations
where the number of sensors required to adequately monitor
different substances or pathways is not feasible, the object is to
identify, monitor, and treat one or more sources common to these.
To eliminate nonessential components, extensive diagnostic testing
is performed before the detailed hardware requirements are
specified, and known causes or results of pathology such as a
lesion is treated before fitting; for example, when operable, a
tumor is resected and if possible, an interval allowed for full
recovery.
[5118] Because the organ is dysfunctional or has become
decompensated, numerous conditions will not respond to a
dynamically targeted dispensing of drugs to different sites of
disease. Where feasible and dependable, a centralized computer in
the medical center could receive sensor inputs and administer the
prescription programs of each center patient by telemetric remote
control through a transceiver implanted in the patient, thus
eliminating the need for an implant microcontroller. However, on
the basis of current dependability of such automation and the
possibility of malicious intrusion, entrusting such a critical
function to a computer and communication by radio, even over a
relatively small area, is premature. In the future, a centralized
supercomputer in a specialty medical center could control all such
implant systems at a high level of patient inclusion, even
nationwide.
[5119] Generally, when transmitted to a center, the output of
individual sensors are sufficient to indicate the associated
symptoms, and by recording these over time allow the diagnosticians
to infer the action required to return the pertinent values to
within the normal ranges (see, for example, Lo, Y. K., Kuan, Y. C.,
Culaclii, S., Kim, B., Wang, P. M., and 7 others 2017. "A Fully
Integrated Wireless SoC [system-on-a-chip] for Motor Function
Recovery after Spinal Cord Injury," Institute of Electrical and
Electronics Engineers Transactions on Biomedical Circuits and
Systems 11(3):497-509; Mirbozorgi, S. A., Bahrami, H., Sawan, M.,
Rusch, L. A., and Gosselin, B. 2016. "A Single-Chip Full-duplex
High Speed Transceiver for Multi-site Stimulating and Recording
Neural Implants," Institute of Electrical and Electronics Engineers
Transactions on Biomedical Circuits and Systems 10(3):643-653 (also
cited above in the section entitled Background of the Invention.
Field of the Invention); Khan, S. R. and Choi, G. 2016. "Analysis
and Optimization of Four-coil Planar Magnetically Coupled Printed
Spiral Resonators," Sensors (Basel, Switzerland) 16(8). pii:
E1219;Kuan, Y. C., Lo, Y. K., Kim, Y., Chang, M. C., an Liu, W.
2015. "Wireless Gigabit Data Telemetry for Large-scale Neural
Recording," Institute of Electrical and Electronics Engineers
Journal of Biomedical Health Informatics 19(3):949-957; Jegadeesan,
R., Nag, S., Agarwal, K., Thakor, N. V., and Guo, Y. X. 2015.
"Enabling Wireless Powering and Telemetry for Peripheral Nerve
Implants," Institute of Electrical and Electronics Engineers
Journal of Biomedical Health Informatics 19(3):958-970; Giagka, V.,
Eder, C., Donaldson, N., and Demosthenous, A. 2015. "An Implantable
Versatile Electrode-driving ASIC [application specific integrated
circuit] for Chronic Epidural Stimulation in Rats," Institute of
Electrical and Electronics Engineers Transactions on Biomedical
Circuits and Systems 9(3):387-400; Tang, S. C., Jolesz, F. A., and
Clement, G. T. 2011. "A Wireless Batteryless Deep-seated
Implantable Ultrasonic Pulser-receiver Powered by Magnetic
Coupling," Institute of Electrical and Electronics Engineers
Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
58(6):1211-1221; Qiu, Y., Haley, D., and Chen, Y. 2014.
"Energy-efficient Adaptive Modulation in Wireless Communication for
Implanted Medical Devices," Conference Proceedings of the Institute
of Electrical and Electronics Engineers Engineering in Medicine and
Biology Society 2014:918-921; Kiourti, A., Psathas, K. A., and
Nikita, K. S. 2014. "Implantable and Ingestible Medical Devices
with Wireless Telemetry Functionalities: A Review of Current Status
and Challenges," Bioelectromagnetics 35(1):1-15; Mutashar, S.,
Hannan, M. A., Samad, S. A., and Hussain, A. 2014. "Analysis and
Optimization of Spiral Circular Inductive Coupling Link for
Bio-implanted Applications on Air and Within Human Tissue," Sensors
(Basel, Switzerland) 14(7):11522-11541Tang, S. C., Jolesz, F. A.,
and Clement, G. T. 2011. "A Wireless Batteryless Deep-seated
Implantable Ultrasonic Pulser-receiver Powered by Magnetic
Coupling," Institute of Electrical and Electronics Engineers
Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
58(6):1211-1221; Ferguson, J. E. and Redish, A. D. 2011, Op cit.;
Ramrakhyani, A. K., Mirabbasi, S., and Mu Chiao 2011. "Design and
Optimization of Resonance-based Efficient Wireless Power Delivery
Systems for Biomedical Implants," Institute of Electrical and
Electronics Engineers Transactions on Biomedical Circuits and
Systems 5(1):48-63).
[5120] In that case, this primary pathology must first be remedied
such as by transplantation. If this restores homeostasis, then the
adaptive hierarchical control implant system serves to control the
targeted dispensing of immunosuppressives to the transplant and
monitor any sequelae in the transplant and native organs. The
inputs to the lowest level comprise sensors that detect specific
indicia of physiological function at each site of morbidity. A
master controller programed to measure deviations from the normal
value for each function takes the subfinally processed data from
the next lower level in the hierarchy oversees and coordinates the
entirety of data, extracting the consequences of administering a
given drug at each site. This identifies the interrelated
consequences among the sites or nidi of a certain drug when
targeted at one of the sites.
[5121] Note that such diagnosis:
[5122] 1. Makes the directly targeted delivery, release,
traceability, and local consequence of use of each drug certain as
to identity and volume as substantially segregated from other drugs
in concurrent use.
[5123] 2. At the same time isolates drugs, minimizing exposure to
other tissue and minimizing or eliminating side effects while
allowing higher doses at the target site.
[5124] 3. The implementation of such a system is dependent upon the
availability of connectors to vessels, to other bodily ductus, and
to nonductal tissue which unlike indwelling catheters and other
connectors cannot become dislodged, compress vasa or nervi vasora,
and will not leak or deteriorate so that these can remain fully
implanted to the end of life.
[5125] Such connectors, described in copending applications Ser.
Nos. 14/121,365 and 14/998,495, are devised to minimize the trauma
of placement, prevent leaks, and impose as little adverse effect on
substrate tissue as the unavoidable need for physical contact will
allow. This includes subsidiary lines to maintain the connectors
and to treat any adverse sequelae such as unwanted tissue reactions
as might arise. The lack of dependable connectors is the ultimate
factor preventing the implementation of artificial intelligence in
fully implantable systems to aright correctible deviations from
normal function to within the normal range when remediable. In some
cases, this will require preliminary surgery or transplantation
before such a system can be applied.
[5126] The direct targeting to the sites or nidi of disease spares
nontargeted tissue from exposure, so that provided it does not
arouse more adverse consequences than it eliminates, a fully
implanted, ambulatory, and automatic scheme of direct piping will
usually surpass the systemic administration of drugs, certainly for
diagnostic purposes. If administering a certain drug at any one
site results in no significant shifting toward or away from the
normal or homeostatic value at each of the other sites, then the
component morbidities are effectively independent, that is, related
only tenuously, as one would expect of part in a unit organism. If
significant, the comorbidity is interdependent.
[5127] Numerous instances of dependent (secondary, sequelary)
impairment such as the cardiorenal syndrome have long been
recognized. If adaptive (self-tuning, capable of learning'), then
when confronted with interdependent comorbid conditions, the master
controller registers the effect of administering a drug at one site
upon each of the detected variables and sum of the others. By
determining and delivering the combination of drugs that
accomplishes homeostasis as might best be approximated, this
accumulated `experience` makes possible the optimization in overall
condition of the patient.
[5128] FIG. 108 shows the hierarchical control system as contained
within an extracorporeal control, power, and pump pack attached to
a waist belt or belt cinched about a thigh. While sensors must be
implanted, the contents of the control, power, and pump pack are
generally implanted when and to the extent that the size of the
components and the condition of the patient permit. To take up the
least space, especially in a prenate, neonate, or young child, full
implantation will usually be decentralized or distributed rather
than centralized. Even in a late term prenate, this affords wide
latitude in positioning the separate tiny encased nodal
microcontroller chips not depictable in two dimensions without
numerous two dimensional sectional views, and accordingly omitted
in FIG. 107.
[5129] In a prenate or neonate, the elimination of wires is
accomplished with ultra-low energy Bluetooth transception. This not
only eliminates the risk of organ or tissue strangulation as it
would in an adult, but eliminates the need for rewiring as the baby
grows. Also to allow for growth, the fluid lines for the direct
pipe-targeting of drugs are made of coiled extendable plastic
catheters which are able to lengthen considerably when the
extension imposed by growth causes their attachments to recede from
one another, the lines then urged to their smallest freely reached
length (see Reum, D. J. 1978. Method for Producing a Spirally Wound
Plastic Article, U.S. Pat. No. 4,120,929). The spring loaded
stent-jackets and relatively thick foam lining of stent-jackets,
impasse-jackets, and nonjacketing side-entry connectors also afford
sufficient latitude to accommodate growth over a lengthy
interval.
[5130] Whereas FIG. 107 shows a fully implanted automatic disorder
response system, FIG. 108 shows such a system in generalized and
simplified schematic form wherein only the sensors and side-entry
jackets are implanted. In a practical system, both side-entry
jackets and nonjacketing side-entry connectors would almost always
be used, and these might or might not incorporate and position the
sensors. These implanted components are shown at the top of FIG.
108 in the box labeled `body.` Connection to the belt-worn power,
control, and pump/reservoir pack includes electrical lines
schematically shown as single and/or fluid lines shown as double or
tubular, which plug into a small port at the body surface
schematically indicated by the word `port` between the top and
center boxes. Generally, the master node is a microprocessor and
the subordinate nodes small chip microcontrollers.
[5131] In the arrangement shown in FIG. 108, the sensors and
jackets at the top of the drawing are depicted as collocated if not
integrated, that is, with sensors incorporated within the jacket,
electrical signals originating with the sensors and drug delivery
directed to the same or a nearby location. The actual implanted
components variable and the connections of these to the components
in the extracorporeal (external) pack variously necessitating
electrical and/or fluid connections, single and double lines rather
than a pictorial representation is used to indicate these
respectively. FIG. 108 necessarily generalized and simplified,
included are only two channels or legs of control, each monitored
by four symptom or physiological indicia sensors directed to either
of the separate morbidities, which may of may not interact to a
significant degree.
[5132] Each set of sensors generate signals which pass to a node
respective of each sensor as shown in the boxed about portion of
the schematic at the bottom of the drawing. These first order
processing nodes pass their data to an intermediate set of nodes in
communication with the primary nodes individually and severally.
These intermediate level microcontroller nodes at the summary level
of the morbidity respective of each pass their data to the master
node microprocessor responsible for integrating the data across
both morbidities to regulate the delivery of drugs from small
implant reservoirs in a coordinated manner to achieve the optimal
homeostatic result for the patient. When the system is placed prior
to surgery that would correct a defect or defects which
significantly contribute to the sensory data profile, the
prescription program and arrangement of components must be adjusted
accordingly.
[5133] When the surgery pertains to anatomy that had earlier been
provided with sensors, adjustments in sensors and their positioning
is accomplished during the surgery. When these factors do not
coincide, the rearrangement can be accomplished after an interval,
but not if continuation of the existing regimen would prove
injurious with the anatomical changes introduced. In many
instances, some components and the prescription program will
require change during the same procedure while others will be
deferred. Because the delivery of therapeutic means whether drugs,
heating, or electrostimulation, for example, is targeted, depending
upon the interdependency of data for any two morbidities,
coordination for the master node may be lessened.
[5134] This does not apply, for example, to an endocrine axis such
pituitary-adrenal or anywhere else that glandular communication is
not limited to detectable changes in reasonably detectable blood
chemistry, blood pressure, or a change in temperature. FIG. 108 is
simplified, in that only two comorbid conditions are represented,
four sensors are assigned to each, and the therapeutic means (in
the center box) are limited to drug therapy. In actuality, any
number of sensors can be assigned to any one morbidity, the
response might include the application of measures to include or
exclude drugs. As the complexity of the system rises with the
addition of each sensor, the number of these should be kept to a
minimum. Were four coexisting morbidities present and two or more
of these were interactive, the burden, processing time, energy
consumption, and heat generation of the master node microprocessor
would be increased.
[5135] This in turn imposes the need for thermal insulation and the
additional if slight space this would require, reducing the number
of sites for placement. If the master node is not to be relegated
to an external pack, then time permitting, tissue expansion should
be accomplished in a preliminary procedure. For this reason, it is
important that the internist clearly specify the need for sensors
and nodes for the prescription programmer. Morbid conditions vary
considerably in the need for more than one or two sensors, and
substantially noninteractive morbidities should not be assigned the
degree of data coordination appropriate for interactive
morbidities. Since ultimately the output or all sensors must be
coordinated with each of the others, the addition of any
nonessential sensor materially increases the overall complexity and
cost of the system.
[5136] Sensor and internodal communication is exclusively
electrical, denoted by single connecting lines, while pump jacket
connections are shown with double lines to indicate that these
connections are tubular for moving fluid. FIG. 108 assumes that the
small reservoir pump motors are steppers, eliminating the need for
closed loop feedback to the directing master node. The capability
of the master node to direct any of a number of drugs by means of
indexing a turret mechanism to place the drug wanted in the
delivery line is described in copending application Ser. No.
14/121,365. As shown, the drug turrets are contained within an
external control, power, and pump pack attached to a waist belt or
cinched about a thigh.
[5137] When drug volumes and the number thereof allow, these too
are implanted, the goal to achieve as close to a fully implanted
system as can be managed. At the interface between the nodes and
pumps between the two lower boxed-about sections in a body pack,
the connections are electrical, the projections meant to indicate
the plugs or jacks and the depressions sockets. In FIG. 108, these
are relegated to the external (extracorporeal) control, power, and
pump pack. In less complex systems where all of the components are
implanted, the only visible component is a small port at the body
surface needed to house button cells and provide openings through
which to pass miniature fiber optic and other cables. Electrical
connections to the port are required only when an implanted battery
is to be recharged through a power supply rather than by
transdermal or transcutaneous energy transfer or a test instrument
is used to evaluate the function of the component attached to the
port socket. Replenishment of the implanted drug reservoirs does
not require external openings, small tattoos used to indicate the
injection points.
[5138] Consistency allowing simplification and assuring minimal
space uptake in prenates and neonates, for example, for implanted
use across all body sizes, every component, to include those used
to achieve wireless internodal communication, must be reduced to
the smallest size possible. This makes possible the elimination or
wires even in prenates and neonates. The patient must not
experience internal sensations associated with system componentry
that rubs against if not abrades neighboring tissue, even if this
later subsides once the parts become encapsulated within fibrous
tissue. In most instances, this eliminates the need for a
preliminary and time-consuming procedure of creating a pocket or
pockets to contain one or more components by means of tissue
expansion.
[5139] Moreover, to provide a system wherein highly concentrated
drugs are diluted prior to delivery likewise demanding a larger
water or liquid reagent supply reservoir and mechanism and means
for switching this among a number of drug vials in any event, a
more elaborate fully implanted real time automatic ambulatory
adaptive/predictive system for response to a number of comorbid
conditions must include some components of which the dimensions
must follow from the absolute volume of the fluid drugs required.
In this circumstance, the hierarchical control system componentry
is best decentralized or distributed rather than centralized, thus
reducing the need for larger spaces to house the required system
modules.
[5140] However, whereas a decentralized hierarchical control system
in an industrial application can usually connect the system
sensors, nodes, and effectors by wire, data intercommunication
among a plurality of components within the body poses a problem, in
that any fluid and electrical line must be routed to assure that
organs and tissues are never strangulated. This may prove
difficult, may require the use of suture, staples, or clips, all
prone to result in discomfort if not pain or more serious
complications, as well as demanding much additional procedural time
to place, even if no unexpected complications arise during the
operation.
[5141] The application of wireless transmission in lieu of hard
wiring to interconnect the decentralized components complements the
application of very large scale integrated, and eventually,
molecular electronics to make the implant system least obtrusive in
relation to older technology hardware implementation of a
hierarchical control system (where the application pertains to high
power or large scale industrial systems, the essential concepts
should be understood as applicable by analogy to microelectronics
in the service of medicine, see for example, Forrester, J. K. 2016.
An Overview of Molecular Electronics, Seattle, Wash.:
Amazon/CreateSpace Publishing; Karroach, R. 2016. Nanoelectronics:
Molecular Electronics, Seattle, Wash.: Amazon/Create Space
Publishing; Zenke, A. 2016. Molecular Electronics: Advanced Topics
in Nanotechnology, Seattle, Wash.: Amazon/CreateSpace Publishing;
Durna, E., evik, Y., Karagoz, M., and Civil, A. 2016. "Design and
Implementation of a Hierarchical Control System Architecture for a
Modular Pulsed Power Supply System," Institute of Electrical and
Electronics Engineers International Power Modulator and High
Voltage Conference, 2016, at
http://ieeexplore.ieee.org/document/8012916/; Kong, Z., Pi, D.,
Wang, X., Wang, H., and Chen, S. 2016. "Design and Evaluation of a
Hierarchical Control Algorithm for an Electric Active Stabilizer
Bar System," Journal ofMechanical Engineering (Ljubljana, Slovenia)
63(12): 565-576; Baldea, L. 2015. Molecular Electronics: An
Experimental And Theoretical Approach, Boca Raton, Fla.: Chemical
Rubber Company Press; Cuevas, J. C. and Scheer, E. 2010. Molecular
Electronics: An Introduction to Theory and Experiment
(Nanotechnology and Nanoscience), (World Scientific Series in
Nanotechnology and Nanoscience), Singapore: World Scientific
Publishing Company; Scattolini, R. 2009. "Architectures for
Distributed and Hierarchical Model Predictive Control--A Review,"
Journal of Process Control 19:723-731; Mahler, G., May, V., and
Schreiber, M. 1996. Molecular Electronics: Properties, Dynamics,
and Applications, Boca Raton, Fla.: Chemical Rubber Company Press;
Bloor, D., Bryce, M. R., and Petty, M. C. (eds.) 1994. Introduction
to Molecular Electronics, Oxford, England: Butterworth-Heinemann;
Murakoshi, H., Kondo, T., Dohi, Y., Anzai, F., Kawahara, N., Takei,
T., and Watanabe, T. 1993. "Hardware Architecture for Hierarchical
Control of Large Petri Net," Proceedings of the International
Conference on Industrial Electronics, Control, and Instrumentation,
1993, available at
http://ieeexplore.ieee.org/document/339096/?reload=true; Jones, A.
T. and McLean, C. R. 1986. "A Proposed Hierarchical Control Model
for Automated Manufacturing Systems," Journal of Manufacturing
Systems 5(1):15-25; Schweppe, F. C. 1978. "Power Systems `2000`:
"Hierarchical Control Strategies," Institute of Electrical and
Electronics Engineers Spectrum Magazine 15(7), in that not only the
components but their interconnections are rendered least
obtrusive.
[5142] Not only is the space required to house the various system
components reduced to the minimum, but the additional procedural
time, difficulties that might arise during placement, and the
possibility of numerous postoperative complications are much
reduced if not eliminated. Equally important, wireless connection
among sensors and nodes is unaffected by growth, allowing placement
in neonates and small children without concern over the possibility
of catching, entrapment, or organ strangulation by electrical lines
during growth. If for any reason, wireless connection is not
advisable, the fluid and electrical lines used are coiled to allow
extension sufficient to last for years before replacement, that of
the electrical lines preferably with wireless interconnections.
[5143] Components of the implanted body-embedded system network
such as a microprocessor master node, if implanted, microcontroller
subordinate nodes, biotelemetric and ultra-low energy `Bluetooth`
radio frequency module internodal transceivers, can be expected to
initially provoke an adverse tissue reaction, recommending an outer
layer of anti-inflammatory medication, usually steroidal. This will
subside and the components become encapsulated by fibrous tissue.
In a fetus, neonate, or child, growth will furnish additional
tissue to dissipate any residual radiated heat. Even after
enclosure to cover over sharp edges and corners, wireless
`bluetooth` ultra-low energy, low power transceiver chips typically
measuring 6.times.6 millimeters pose no heating or space
accommodation problem.
[5144] For implantation, however, any component which operates
sensibly above body temperature should be packaged to prevent heat
radiation at this level. Means for quantifying heat generation are
available (Sajith, V. and Sobhan, C. B. P. 2012. "Characterization
of Heat Dissipation from a Microprocessor Chip Using Digital
Interferometry," Institute of Electrical and Electrical Engineers
Transactions on Components, Packaging and Manufacturing Technology
2(8):1298-1306; Mahajan, R., Chiu, C., and Chrysler, G. 2006.
"Cooling a Microprocessor Chip," Proceedings of the Institute of
Electrical and Electronics Engineers 94(8):1476-1486; Viswanath,
R., Wakharkar, V., Watwe, A. , and Lebonheur, V. 2000. "Thermal
Performance Challenges from Silicon to Systems," Intel Technology
Journal, at
http://www.intel.com/technology/itj/q32000/articles/art_4.htm).
While general purpose high capacity central processing units such
as the Intel i7 series have an average maximum operating
temperature of 142 degrees Fahrenheit, the full-load temperature
will normally average about 45 degrees Fahrenheit, well within the
acceptable range.
[5145] The risk of excessive heat is substantially pertinent to
only the highest capacity processing units and then only when these
are under intensive use, that is, operated under a constant full
workload (Stone, D. 2017. "What is the Average Temperature of an
Intel i7 Processor?," Hearst Newspapers Chron, at
http://smallbusiness.chron.com/average-temperature-intel-i7-processor-816-
59.html). It is improbable that any but a master node controller, a
special rather than general purpose processor, would pose a problem
of excessive heat. Other microprocessors in a distributed node
system are lighter duty and pose little risk of excessive heat. If
in fact numerous comorbidities are involved and the remedies
proposed below do not resolve the problem, the master node
controller can be worn on the outside of the body. The reciprocal
condition--the effect of the temperature of the body on the
processor is not a problem
[5146] Lifelong implantation of microcircuits requires that heat
dissipation be reduced to the extent possible, both to preserve the
service life of the circuitry itself and to prevent the transfer of
heat to the surrounding tissue, which if significantly higher from
microcircuits not intentionally intended to do double service for
thermoplasty, would prohibit implantation. Implantation circuity to
support an implanted automatic disorder response system as
described herein and in copending applications Ser. No. 14,121,365
now 20160051806 and Ser. No. 14/998,495 now 20170197028, consists
of the master and control nodes, biomedical, and wireless
internodal transceivers.
[5147] Quite apart from the prospect of implantation, means for
minimizing the generation of heat to extend processor service life
have been ongoing for years, heat sinks, heat spreaders and
thermal/ground pads, for example, long in use. To enclose a
component within an insulating shell prevents heat from radiating
into the surrounding tissue but traps the heat inside the shell,
reducing service life. One approach is to counter the heat by
including Peltier devices, cascaded if necessary, with hot sides
attached to heat sinks.
[5148] Other than to cover over sharp edges and corners, few master
node microprocessors, much less subordinate node microcontrollers,
biotelemetric or ultra-low energy `Bluetooth` transceivers, or
system on a chip modules unifying a node with its transceiver
should require the enclosure to provide thermal insulation. The
space taken up by the thicker wall this necessitates takes up space
that more significantly in a fetus, neonate, or small experimental
animal risks encroachment upon neighboring tissue. To avoid
deviations in operating frequency due to inconsistencies in the
power supplied as the battery discharges, only superheterodyne
receivers are used. To avoid electrostatic discharge which can
damage integrated circuits, it is essential that handling, system
assembly in preparation for implantation, and implantation in a
precautionary manner.
[5149] At full load, transceivers other than ultra-low power
Bluetooth can generate heat well above that suitable for
implantation. To specify whether implantation or implantation with
the ameliorative measures specified above is an option, or the
transceiver module must be worn outside of the body, the maximum
potential workload for the specific system and functions proposed
for implantation must be known. The shell in this case serves to
cover over the sharp edges and corners of the nodal
microcontrollers and transceivers, if any (Incropera, F. P. 1988.
"Convection Heat Transfer in Electronic Equipment Cooling," Journal
of Heat Transfer 110(4b): 1097-1111).
[5150] Small scale microprocessors programmed as nodes incorporate
heat reduction means and should not pose a heat problem, despite
the need to enclose these within a nonallergenic plastic shell to
cover over sharp edges and corners. Replacing metal wires with
optical fibers remains to yield cooler running microcircuits or
core communications (Templeton, G. 2016. "Here's Why We Don't Have
Light-based Computing Just Yet," at
https://www.extremetech.com/extreme/223671-heres-why-we-dont-have-light-b-
ased-computing-just-yet.
[5151] When the tissues or organs to be treated are not deep and
the patient is a competent adult, system placement--even when
including numerous components--can usually be accomplished using
local anesthetic nerve blocks, thus averting the persistent
numbness associated with neurolytic block, the high risk for
postprocedural deafferentation or neuronal pain following
neurectomy or the crushing of sensory fibers, and the cognitive
problems associated with the use of general anesthesia.
[5152] Implanted electrical lines are eliminated through wireless
transmission. Here, in contrast to the intracorporeal use thereof
to date, which is to transmit from within the body to the exterior
(see, for example, White, J. and Tumlin, K. 2013. Apparatus and
Method for Sensor Deployment and Fixation, U.S. Pat. No. 8,355,777;
Gilad, Z. 2012. System for In Vivo Detection of a Body Lumen,
Japanese Patent 5,039,378), the use of ultra-low energy wireless,
or `Bluetooth` transmission is used to allow data transfer among
sensors and control nodes when some or all are implanted within the
body. The form factors and absolute size of wireless
transmitter-receivers now makes it possible to use these even in
near term prenates. The wide discrepancy in carrier frequencies
used for wireless and biotelemetric transmission substantially
eliminates the possibility of interference between the two, to
include their harmonics (see, for example, Laskovski, A. N. and
Yuce, M. R.2008. "Harmonics-based Bio-implantable Telemetry
System," Proceedings of the Annual Conference of the Institute of
Electrical and Electronics Engineers Engineering in Medicine and
Biology Society 3196-3199).
[5153] In the United States, Bluetooth ultra-high frequency (UHF)
ultra-low energy short-range radio carriers are assigned the
industrial, scientific and medical (ISM) band from 2.4 to 2.485
gigahertz. Biotelemetric transmission to the clinic is assigned to
a long-range biotelemetric radio frequency band from 608 to 614
MHz, or from 1395 to 1400 MHz; or from 1427 to 1432 MHz, shared
with non-medical telemetry operations. In the United States,
different frequency ranges apply in different regions; however,
whichever is used, interference between biotelemetric and ultra-low
energy Bluetooth signals or their harmonics does not occur. Neither
should carrier frequencies assigned to garage door openers or
keyless door entry systems, for example, hopping or rolling coded
between 300 to 400 MHz, ever cause interference.
[5154] XXII. Glossary of Terms
[5155] Ablation-capable barrel-assembly--A radial discharge
barrel-assembly (qv.), or airgun barrel-extending catheter, that
can apply heat (electrocautery; thermal cautery), cold (cryogenic
cautery; cryocautery), and/or shaving or abrading action to ablate
lumen-obstructive matter in any type of ductus. Lacking internal
gas pressure relief passages to prevent gas embolism, often using
different thermal or cryogenic temperatures, and lacking an
ischemia-averting outward conformation, it is not for use in the
vascular tree. Except in diameters suited for use in narrower
bronchi and ureters, it is also too large in diameter for use in
blood vessels. By contrast, a smaller gauge device, an ablation and
angioplasty-capable barrel-assembly (qv.), includes these features,
and is always capable of performing an ablation in a nonvascular
ductus. A minimally-capable embodiment is meant to ablate minimally
as immediately preparatory to implantation in a single procedure if
not a single pass. For economy, a minimally-capable embodiment is
not usable apart from and dependent upon connection to the airgun
power supply through contacts at its end-plate through an
end-socket (qv.). By contrast, a fully capable unit, whether
bipartite (qv.) by combining a minimally-capable unit with a
matching combination-form radial projection catheter (qv.) or as a
self-contained apparatus, can be used to perform an ablation while
physically independent from the airgun and without regard to
whether it will thereafter be inserted into an airgun to initiate
stenting discharge; airgun-independent capable barrel-assembly. Cf.
angioplasty-capable barrel-assembly; ablation and
angioplasty-capable barrel-assembly.
[5156] Ablation and angioplasty-capable barrel-assembly--A radial
discharge barrel-assembly (qv.), or interventional airgun barrel
extension-catheter, which is capable of performing an ablation or
an angioplasty while separate from an airgun. Such capability
requires either one or more radial projection systems (qv.) about
the muzzle-head, or if bipartite (qv.), accession to these
components through ensheathment within a matching combination-form
(qv.) radial projection catheter (qv.), or a central channel (qv.)
for accepting a cabled ablation or atherectomy device, such as a
laser or atherectomy cutter. Because it provides a central channel
for a cabled apparatus, the latter is referred to as a through-bore
or combination-form (qv.) ablation and angioplasty-capable
barrel-assembly with radial projection system. Only a
barrel-assembly of millimetric gauge that include gas pressure
relief channels is also capable of performing an angioplasty. For
both ablative and angioplasty capability, the barrel-assembly must
also be equipped with radial projection units (qv.) and
tool-inserts (qv.) having the temperature and material removal
rates required for either process. Incorporating a control panel
atop the onboard power and control housing, it is self-contained
and can be used separately from or while engaged in an airgun.
While in the airgun, its is generally controlled from the airgun
control panel; when separate, from the control panel atop its power
and control housing. This allows both free movement and implant
discharge capability without the need for withdrawal from the
lumen; airgun-independent capable barrel-assembly. Cf.
ablation-capable barrel-assembly, angioplasty-capable
barrel-assembly, combination-form radial projection catheter.
[5157] Ablation and angioplasty-incapable barrel-assembly--A
barrel-assembly (qv.), such as a simple pipe or solely discharge
radial discharge barrel-assembly for insertion in an aigun as an
endoluminally insertable extension of the airgun barrel and lacking
features used for ablation and angioplasty; plain discharge
barrel-assembly, limited purpose barrel-assembly;
airgun-independent incapable barrel-assembly.
[5158] Active delivery [to an impasse-jacket, outrigger, or other
type jacket]--Direct injection or infusion into an impasse- or
other type jacket or the substrate (encircled, treated) ductus
upsteam from the jacket. Includes the use of a catheter to the
jacket from an infusion set cannula and patch, Ommaya reservoir, or
similar portal positioned cutaneously, subcutaneously
(subdermally), or having openings both cutaneous and subcutaneous
at the body surface. This serves as a conduit to supply or evacuate
(aspirate) an impasse-jacket (qv.) or outrigger (qv.) by a syringe
or portable pump when passive delivery by the bloodstream or other
ductus contents is inadequate. Inadequacy may, for example, involve
dosing, timing, or the need to supply multiple impasse-jackets with
different drugs in different concentrations at differrent
intervals, making passive or statistical apportionment unreliable
when even possible. Both active and passive delivery apply no less
to nonmagnetized jackets. Cf. passive delivery.
[5159] Actuation-aspiration switching valves--A perforated plate or
baffle positioned in the path of a flowing fluid that is mounted to
act as a resistor when flow is in one direction and lever aside
when the direction of flow is reversed. One is positioned in the
the roof of the outlet chamber of the radial projection unit
lifting mechanism. During actuation or antegrade flow through the
supply line, that valve closes increasing resistance to continued
flow through the line causing the inflowing fluid to be diverted up
against the base of the tool-insert (qv.). During aspirative or
retrograde flow, the inflowing fluid pushes the valve that opens at
an angle at its outlet side allowing particulate debris to flow
through, at the same time that it forces the line fluid to rush
past the opening that leads up into the tool-insert thus creating a
vacuum. This primary valve can be reversed repeatedly until the
buildup of debris forces flushing the line with sodium hypochlorite
then water at high pressure or switching to the use of a separate
fluid circuit. A second fluid resistor in the base hole or
base-plug of the tool-insert consisting of a thin wafer or film of
sugar, for example, will pose a tool-insert-specific secondary
resistance opposing flow up through the tool-insert but once. To
allow tool-inserts along the line to alternate between actuation
and aspiration repeatedly, this secondary resistor is likewise made
as a reversible valve. The perforated plate or baffle resistor
shuts during radially outward (actuative, antegrade) flow and opens
at an angle during inward (aspirative, retrograde) flow. Cf.
aspirator, baffle.
[5160] Adhesive-hardener--A binder and fixative applied to miniball
and stay implants to knit together the implant and the loose
(diffuse) or weakened tissue surrounding it.
[5161] Adhesive-hardener field--The region surrounding the
intraparietal implant through which the adhesive-hardener (qv.)
coating it upon being implanted extends once cured. When positioned
closely together, adjacent fields may coalesce or merge together to
form a unitized scaffold embedded within the wall of the ductus
that serves to reduce migrability.
[5162] Adjusting stent-jacket--A stent-jacket (qv.) with an
expansion insert (qv.) along one or both free edges facing across
the side-slit (qv.). Using absorbable materials in order of
absorption, the stent-jacket is made to close over time, ideally,
in step with subsidence in the initially enlarged ductus;
contracting stent-jacket.
[5163] [Interventional] Airgun--An airgun adapted or specially
devised to introduce or infix temporary drug-releasing or
circumvascular stent retracting ferromagnetic implants into the
wall of a ductus, for example. Angioplasty-capable
barrel-assembly--A radial discharge barrel-assembly (qv.) that
unlike a simple pipe or a solely discharge or limited purpose
radial discharge barrel-assembly, can serve to perform an
angioplasty without regard to subsequent insertion in an airgun to
initiate stenting discharge. An angioplasty-capable barrel-assembly
may incorporate only radial projection units (qv.) with trap-filter
(qv.) or it can be of a combination-form type that also
incorporates a laser or rotational burr. When the temperature range
of its radial projection units and material removal rates of its
tool-inserts is sufficient for ablation, the same apparatus can be
used for an ablation in lumina of similar diameter. Used manually
without insertion in the airgun and prior to insertion in the
airgun when ballistic implantation stenting is to follow, an
angioplasty-capable barrel-assembly has a free extracorporeal end,
and independently powered, is untethered for free and independent
manual use. Should the barrel-assembly require advancement or
retraction in increments too small for manual control, the free end
of the barrel-assembly is inserted into the airgun barrel and the
linear positioning stage used; angioplasty barrel-assembly. Cf.
ablation-capable barrel-assembly, ablation and angioplasty-capable
barrel-assembly.
[5164] Antemagnet chamber--The enclosed space in front of a
miniball recovery and extraction recovery tractive electromagnet
and behind the spring-loaded door, which is flush with the outer
surface of the muzzle-head. The door springs urge the door to
re-close outwardly after a loose or extracted miniball, drawn into
and trapped within the space by attraction to the magnet, has
pushed the door open; magnet-trap (as opposed to filter-trap
(qv.).
[5165] Anteport extension--The portion of the muzzle-head, and when
pertinent, the distance of trap-filter projection distal to the
exit ports and length thereof. The extension fixes the distal reach
or limit out to which the muzzle-head can discharge.
[5166] Anti-migration lining--A layer applied to the internal
surface of a stent-jacket (qv.) in order to reduce if not eliminate
lateral displacement. When the muscular forces intrinsic in the
substrate ductus or its exposure to external forces recommend,
additional protection against migration is obtained through the use
of stent-jacket end tethers (qv.).
[5167] Anti-perforation lining--A layer applied to the internal
surface of a stent-jacket (qv.) in order to eliminate the risk of
escape outside the ductus and to reduce if not eliminate the
intensity or residual momentum of rebound as could cause the
miniball (qv.) to enter the lumen.
[5168] [Stay-] arms--The extensions from the perpendicular midline
of a stay (qv.). Stay must be kept short in proportion to the
change in luminal circumference during expansion and contraction
and the inflexibility of the arms. An ideal stay bends with changes
in diameter of the ductus wall as would a tiny unstrung archer's
bow; however, antecedent claims on the constitution of most
practical stays usually disallow unrestrained compliance thus.
[5169] Articulated stent-jacket--A chain-stent (qv.) consisting of
separate sub-stents connected, for example, by nonmagnetic
stainless steel wire links to allow flexion or to bridge over a
segment or segments of the ductus not to be stented. Different
sub-stents can have side-slots (qv.) rather than side-slits (qv.)
to allow a subjacent attachment to remain. Unlike a segmented
stent-jacket (qv.), the substents can be very different in
structure and distance to the next closest sub-stent. Cf.
chain-stent, mixed chain-stent.
[5170] Aspirator--A barrel-tube (qv.) port, nose-hole at the distal
terminus of the central channel (qv.), or a fluid radial projection
tool-insert (qv.) when used to create a vacuum for the removal of
ablation or angioplasty generated debris or excess ejectant or to
retrieve misplaced miniballs (qv.). At subinjurious pressures, port
vacuum can aid in stabilizing the muzzle-head in contact relation
against the lumen wall. Ejector-irrigator-tool-inserts capable of
alternately ejecting or irrigating and aspirating repeatedly must
be equipped with actuation-aspiration switching valves (qv.).
[5171] Auxiliary syringe--A syringe or syringes containing
medication, tissue sealant, a tumefacient, or intimal-medial
swelling agent, scar tissue inducing agent or any of these in
combination, attached to a stay (qv) insertion tool (qv) by means
of a holding frame (qv). The unloading of syringes, which may be
dual- or other multi-syringed, can be directly controlled by the
operator or by an interval timing relay. When the latter, the
unloading of syringes attached to the right and left of the stay
insertion tool (qv.) may require to be independently coordinated in
relation to the stay insertion tool (qv) ejection cycle (qv). When
operation of auxiliary syringe is to be integral with the ejection
cycle (qv.), contol is under an inmate mixed-signal microcontroller
embedded in the tool (not the auxiliary syringe attachment; the
inmate microcontroller can be reprogrammed to accommodate different
auxiliary syringe ejection cycles). The various types of substances
applied can be mixed or segregated in syringes mounted at either
side of the insertion tool for clear distinction in use.
[5172] Baffle--A fluid resistor consisting of a plate containing
slits or perforations which is situated in the path of the fluid
moving through a fluid radial projection system (qv.) or fluid
circuit. Within a lifting mechanism a square baffle is used as a
hinged roof over the outlet chamber (qv.) that serves to divide an
antegrade flow so that a portion is forced to continue up into the
tool-insert (qv.) and the rest continue down the circuit. During
aspiration or retrograde flow, the baffle lifts up out of the path
of the fluid thus minimizing clogging by aspirated debris. One or
more baffles can be positioned along the throat of a fluid
tool-insert base-plug (qv.) to increase the force acting to raise
the lift-platform and/or to reduce the rate of tool-insert flow
through. The shape of the baffle or baffles vary with the cross
section of the throat or fluid path through the base-plug. Cf.
actuation-aspiration switching valve, aspirator.
[5173] Ballistic component--In a barrel-assembly (qv.), the
component that consists of the barrel-tube or tubes, recovery
tractive or trap-extractor electromagnets, and if for use in the
bloodstream, gas pressure diversion channels. Distinguished from
the c entral component (qv.) when present, which is a channel along
the central axis of the catheter for receiving a cabled device, and
from the peripheral component when present (qv.), which consists of
a radial projection circuit or circuits (qv.) about the periphery
of the barrel-assembly. In monobarrels (qv.), whether simple pipes
(qv.) or radial discharge barrel-assemblies, the ballistic
component may be solitary or combined with a peripheral component.
A radial discharge monobarrel for use in vessels may include all
three components. A barrel-assembly with peripheral component, with
or without a central component, is an ablation or ablation and
angioplasty-capable barrel-assembly. When all three components are
present, a barrel-assembly that includes a central component is
more precisely described as a through-bore or ablation or ablation
and angioplasty-capable combination-form (qv.) barrel-assembly.
With or without a peripheral component, a barrel-assembly with a
central component is a combination-form barrel-assembly. The lack
of a ballistic component defines a separate radial projection
catheter.
[5174] Barrel-assembly--An airgun barrel-extending catheter devised
for performing interventional procedures. When ablative or
angioplasty-capable, this apparatus functions in such capacity as
physically separate from and independently of the airgun, then must
be engaged in the airgun for implant discharge. Insertion in the
airgun chassis (qv.) or cabinet makes the barrel-assembly the
barrel of the airgun for the purpose of discharging tiny miniball
implants, usually, into through the internal surface of a ductus
lumen. A barrel-catheter (qv.) with muzzle-head (qv.) as a unit. An
angioplasty-capable barrel-assembly includes components so that it
can be used for angioplasty without regard to subsequent stenting,
whereas a limited purpose barrel-assembly can only be used to
deliver miniballs. Cf. ablation or ablation and angioplasty-capable
barrel-assembly; minimally ablation or ablation and
angioplasty-capable barrel-assembly.
[5175] Barrel-catheter--The larger tube in a barrel-assembly (qv.)
that contains the barrel-tubes (qv.). In a simple pipe type (qv.)
barrel-assembly, the barrel-catheter, and barrel-tube are one and
the same, whereas in a compound barrel-assembly, which contains two
or more barrel-tubes, the need to distinguish between the barrels
within and the larger diameter tube containing these exists. In a
duplex (composite, bipartite) (qv.) angioplasty-capable
barrel-assembly, the barrel-catheter serves in effect as a
guidewire over which the complementary radial projection catheter
is slid into concentric relation as a sleeve that adds radial
projection units.
[5176] Barrel-channel--The portion of each barrel following or
distal to the terminus of the barrel-tubes where continuation is
through the rotating nonmagnetic metal or spindle portion of the
muzzle-head. The junction of the barrel-tubes with the
barrel-channels is always by a joint of constant internal diameter
across the junction which is slidable or reciprocating when the
pliancy of the barrel-tubes or a lack of sufficient slack results
in distortion or kinking of the barrel-tubes but is otherwise
bonded.
[5177] Barrel insertion segment--The proximal length of an
angioplasty barrel-assembly that is inserted into the barrel of the
airgun to initiate ballistic implantation. Arranging that the
hand-grip shaped onboard battery pack, which is used to power the
barrel-assembly while used independently of the airgun and the
airgun or a separate power supply for angioplasty, can be slid
proximally along the barrel-catheter allows the proximal segment of
the barrel-assembly to be used intracorporeally, reducing the
overall length of the barrel-assembly required for a given
procedure; overhang.
[5178] Barrel-tube--An airgun miniball propulsion and directing
channel analogous to the barrel of a firearm. In a simple pipe, the
one barrel-tube comprises the sum of the barrel-assembly, which
consists of a single barrel-catheter, whereas in a two or four-way
radial discharge barrel-assembly, the generally two to four
barrel-tubes are contained within the barrel-catheter. Its distal
end is the muzzle-head. A barrel-tube to be used as a
service-channel (qv.) prior its use for discharge must be lined by
a service-catheter (qv.); otherwise, it can serve as the
service-catheter itself.
[5179] Base-layer--The layer to which another layer or layers is
laminated to add resilience, remote heatability, or radiation
shielding, for example. Lamination is by chemical adhesive bonding,
heat sealing, or heating a ferromagnetic doped coating by induction
heating, for example.
[5180] Base-plug--An extension down from the bottom of a
tool-insert that in an electrical radial projection circuit
provides the electrical connection to power the electrical
component or components internal to the electrically operated
tool-insert but not raise and lower the lift-platform, and in a
fluid circuit provides connection to the fluid line to raise and
lower as well as provide power to the fluid operated component of
components internal to the fluid operated tool-insert. In a
tool-insert without internal components that are electrically or
fluid operated, a dummy base-plug without connectors to the power
line serves to secure the tool-insert in the holding and
lift-platform by friction fit.
[5181] Base-tube--In a stent-jacket (qv.), the segment of tubing
that serves as the pliant platform upon which the perpendicularly
magnetized bar magnets are mounted. Its inner surface serves to set
the limit to the excursion or distance from the central axis of the
lumen to which the ductus wall can be drawn, and no more distant
from the external surface of the ductus than is necessary to effect
sufficient patency or normal blood (TIMI III) flow, prevents
stretching injury.
[5182] Base-tube (slit) expander--A stent-jacket base-tube slit
expanding hand-tool used to expedite placement into a surrounding
or circumvascular relation of a stent-jacket and a vessel or
duct.
[5183] Bipartite [ablation or ablation and angioplasty-capable]
barrel-assembly--A barrel-assembly (qv.) comprising an inner axial
barrel-assembly proper, the primary, and an ensheathing or
ensleeving secondary slide-over or slide-on through-bore, or
combination-form (qv.), radial projection catheter (qv.), that adds
additional capabilities. Standardized diameters allow matching any
number of otherwise independent radial projection catheters of like
size to a given barrel-assembly proper, or primary, as secondaries,
or slide-overs, which can be exchanged or `swapped` midprocedurally
using the intracorporeal primary in the manner of a guide wire.
Other type ensheathing catheters are used to increase the diameter
of the barrel-assembly and/or jacket the primary within a heating
or chilling mantle. Sliding one radial projection catheter over
another can be used when a proximal segment of the ductus is
distended; the outer projection catheter is withdrawn before the
narrower stretch is entered. Nesting radial projection catheters is
possible because tool-inserts withdraw beneath the outer surface to
leave the surface of the inner projection catheter smooth;
composite barrel-assembly, duplex barrel-assembly.
[5184] Blank [tool-insert]--A tool-insert with a continuous flat
inert working face, unperforated and without cutting or injecting
parts. Blanks used to nudge the muzzle-head into the opposite
radial direction elevate and retract. The working faces of
temperature changing blanks generally remain flush to the surface
of the muzzle-head (qv.) or radial projection catheter (qv.).
Electrical blanks containing a coil can only heat, whereas fluid
circuit blanks can deliver heat or cold according to the
temperature of the fluid in the supply line. Only nonblank
tool-inserts can deliver the fluid, which can be a drug as well as
driving medium, into the lumen or lumen wall.
[5185] Blanked [rotary magazine] clip--a rotary clip inserted to
eliminate a number of barrel-tubes of the barrel-assembly from use,
usually to treat eccentric lesions. The holes in the clip that
would nomrally retain the miniball or miniballs for barrel-tubes to
be eliminated are reduced in diameter or eliminated.
[5186] Blood-groove--Longitudnal furrows or running depressions
that run along the outer surface of the barrel-catheter and
muzzle-head portions of the barrel-assembly to allow some
circulation of blood. The blood-grooves or depressions are made as
deep and as wide as the requirement to not encroach upon the
internal barrel-channels allows.
[5187] Blood-port--An open space in the muzzle-head through which
blood can flow created by removing nonessential metal.
[5188] Blood-tunnel--A channel through the barrel-catheter to
provide a passage for the flow of blood that also stiffens the
catheter.
[5189] Bounce-plate--An angled surface mounted to the end of the
muzzle-head of a simple pipe barrel-assembly to alter, generally
reverse, the angle of discharge. The simplest bounce-plates
necessitate withdrawal of the barrel-assembly to attach or adjust.
To reduce procedure and anesthetization times, mechanisms that
allow the deployment and retraction, and in more capable forms,
adjustment in the angle, of a bounce-plate intracorporeally are
provided; rebound angle deflection plate, rebound deflection-plate,
deflection-plate, rebound-plate; ricochet-plate; strike-plate;
rebound-tip; ricochet-tip; rebound strike-tip. Cf.
Strike-point.
[5190] Bounce-wedge--The outer or abluminal component of a
double-wedge insert lining (q.v.) for a shield-jacket (q.v.) or a
stent-jacket (q.v.) that serves as a rebound surface of specified
angle and resilience to shift the trajectory of the miniball away
from the lumen toward a terminus within the wall of the ductus
where it can afford function. A special purpose base-tube can be
made that increases in thickness from end to end, eliminating this
element; however, a universally applicable insert for a section of
any tubing material is more versatile and economical; bumper,
bumper-wedge, deflection-wedge, rebound-wedge. Cf. foam-wedge.
[5191] Braced impasse-jacket--A simple trap- (guard-) or
holding-impasse-jacket (qv.), which includes one trap or one
holding jacket (qv.) or collar, stabilized against abrupt and
potentially injurious displacement during an extraction through
elongation by fastening unmagnetized dummy-collars, or outriggers,
at either or both ends by means of rigid bendable bridge-arms
(qv.). The structure overall constitutes a unitized weldment or
brazement which can be bent to follow a curve, for example. A
braced impasse-jacket with more than one dummy-collar at either end
is one type of chain impasse-jacket. Another type includes more
than two magnetized jackets, each used either to retain miniballs
as a holding jacket or stop miniballs from passing as a
trap-jacket, and yet another combines one or more stent-jackets and
an impasse-jacket. The lengthened structure better resists sudden
repulsion-normal or ductus-transverse displacement (qv.) and
margin-levering (qv.) when repelled by a powerful external
electromagnet during an extraction and allows spanning over or
straddling segments that may be severely lesioned, must flex, or
would best be left attached to neighboring tissue. Since compound
(qv.) and chain impasse-jackets (qv.) are inherently braced, the
term `braced` is used to denote a simple-extended or individual
trap or holding impasse-jacket with at least one dummy-collar at
one end; simple-extended impasse-jacket.
[5192] Break-seal--A film or plate used to block the entry into a
fluid injection or ejection tool-insert (qv.) in order to set a
threshold line pressure to assure local and circuit flow-through.
When singular, it is placed at the bottom or top of the the
base-plug (qv.). Break up of the seal allows the tool-insert to be
used as an aspirator upon reversing the direction of flow through
the fluid supply line. The film must break so that when pushed into
the syringe, the pieces will not clog the hypoendothelial or
hypointimal injection needle or the outlets of the ejector.
Antegrade flow can be reinitiated following retrograde or
aspirative flow, but with the seal having been removed, no
preliminary threshold pressure will precede emission. When
aspiration generates sufficient force, a 2-way slit or otherwise
perforated membrane allows directional reversal to allow actuative
or antegrade and aspriative or retrograde flow to be alternated.
Cf. push-through stopper; slit-membrane. [Impasse-jacket]
Bridge-arms--Extension spans connecting the sections of a
multipartite or multicomponent impasse-jacket. Cf. Braced
impasse-jacket, compound impasse-jacket, chain impasse-jacket.
[5193] Capillary cooling catheter--A fine service-catheter (qv.)
for quickly returning the turret-motor, miniball recovery
electromagnets, and/or heated radial projection unit tool-inserts
to normal body temperature. It can enclose a coolant and have been
refrigerated, then passed down the barrel-assembly when needed, or
have a closed distal end and side-holes through which chilled air
or high purity 1,1,1,2-tetrafluoroethane (R134a) cryogen spray, for
example, is pumped at low pressure; cooling capillary catheter;
capillary chilling catheter, temperature changing capillary
catheter (qv.).
[5194] Butt-pad--A cushion at the bottom of the butt to prevent
injury to adjacent and subjacent tissue.
[5195] Cement-ahead operation--In a stay insertion tool (qv.), the
control of cement delivery to initiate outflow between stay
ejections. The deeply surface textured stays that are usually used
to reduce squeegeeing during entry pass through the cement while
being inserted into the wall of the ductus, thus carrying cement
forward and ductus-intramurally on both upper and lower surfaces.
Bonding to the subjacent and superjacent layers of the tunics
lessens the risk of laminar separation. An adjustable cement air
pump pressure relief aperture allows varying the amount of cement
released; cement-before operation. See also medication-ahead
operation.
[5196] Cement-follower operation--In a stay insertion tool (qv.),
the control of cement delivery to initiate outflow over an interval
during the insertion of the stay through the wall of the ductus. An
adjustable cement air pump pressure relief aperture allows varying
the moment of cement outflow initiation and duration onto the upper
surface of each stay. For sealing the stay insertion incision,
cement is applied only to the tail end of the stay. To retain more
of the cement during insertion, the portion of the upper surface of
the stay is deeply textured; cement-during (stay insertion, stay
infixion) operation. See also medication-follower operation.
[5197] Center discharge barrel-assembly--A barrel-assembly lacking
a burr or laser atherectomy cable running down its center, which is
thus free for use as peribarrel space, and the closer positioning
together longitudinally of the barrel-tubes.
[5198] Center discharge muzzle-head--The muzzle-head (qv.) in a
center discharge barrel-assembly (qv.).
[5199] Centering device--A disk with holes placed at intervals
along the barrel-assembly, which is used to space the
longitudinally disposed barrel-tubes that course through it at the
concentric distances desired. The intervals along the
barrel-assembly and slidability or bonding of the barrel-tubes to
these allows considerable variability in the flexibility and
torqueability of a barrel-assembly made of tubes of a given
material; centring disks.
[5200] Central canal--In a barrel-assembly (qv.), the longitudinal
axial space that extends from the terminal plate (qv.) to or
through the muzzle-head (qv.). In a non-combination-form
barrel-assembly, the central canal ends distally at the back of the
ejection head and is used for pressure equalization to prevent gas
embolism. It contains the wires to the turret-motor (qv.) and
recovery electromagnets. See also side-canal.
[5201] Central channel--The bore through a combination-form (qv.)
barrel-assembly (qv.) or radial projection catheter (qv.) for
passing a permanently installed or interchangeable cabled device so
that it emerges at the nose. Combination-form radial projection
catheters that ensheath a barrel-assembly of like diameter yield a
bipartite (or divisible) ablation or ablation and
angioplasty-capable barrel-assembly (qv.).
[5202] Central component--A commercial device such as an endoscope,
intraductal ultrasonograph, laser, atherectomizer, or
thrombectomizer incorporated into a barrel-assembly (qv.). When
more than one barrel-tube is present, this component is usually
placed between or amid these, hence, the designation central. If
the commercial device imparts ablative or angioplastic capability,
the barrel-assembly is ablation or ablation and
angioplasty-capable. The addition of a radial projection system can
enhance this capability.
[5203] Chain-guard [miniball impasse-jacket]--Either a miniball
impasse-jacket (qv.) that includes more than the two magnetized
impasse-jackets used to trap miniballs provided by a compound-guard
Impasse-jacket, or a braced (qv.) trap-jacket (qv.) that includes
more than one dummy-collar or outrigger at either end of the single
magnetized jacket at the center to trap miniballs; chain-trap.
[5204] Chain [miniball] holding jacket--Either a miniball
impasse-jacket (qv.) that includes more than the two constituent
magnetized jackets used to hold medication and/or radiation
miniballs in suspension within the lumen (usually in the
bloodstream) provided by a compound holding jacket, or a braced
(qv.) holding jacket (qv.), that includes only one magnetized
impasse-jacket and more than the one position-stabilizing
unmagnetized dummy-collar or outrigger provided by a braced holding
jacket. Chain jackets that include more than two magnetized
impasse-jackets are triple, quadruple, and so on, where each jacket
can serve the same purpose as a trap or holding jacket, or differ
in this, being mixed triple or mixed quadruple chain-jackets, for
example. The dimensions and interval separating consecutive jackets
in a chain depends on the anatomy involved.
[5205] Chain [miniball] impasse-jacket--A--braced impasse-jacket
(qv.) which includes more than one unmagnetized dummy-collar, or
outrigger, at either end, or a compound impasse-jacket (qv.) that
includes more than two impasse-jackets. In any jacket, the
constituent magnetized and unmagnetized jackets are joined at their
ends by bridging arms fastened by resistance welding or furnace
brazing. The unitized weldment or brazement allows lengthening the
structure overall to resist end or margin-levering by a
jacket-repelling/miniball-attracting extraction electromagnet
(qv.), and to span across (straddle, skip over) segments of the
ductus, usually an artery, that are diseased, curved, must flex, or
would best be left attached. In the compound type, all of the
individual or constituent jackets, although structurally the same
except perhaps in dimensions, may be used as holding or
trap-jackets. Most compound and chain impasse-jackets include
holding jackets (qv.) with one or two trap-jackets and are
therefore said to be mixed or composite impasse-jackets. Chain
impasse-jackets are inherently braced (qv.) for positional
stabilization in the even of the need to extract a miniball from
the jacket with the aid of an external electromagnet. Most chain
impasse-jackets include holding jackets (qv.) with at most one or
two trap-jackets; impasse and extraction jacket. Cf. braced
impasse-jacket, bridged-guard, braced-guard.
[5206] Chain-stent--Collective term for articulated (qv.) and
segmented (qv.) stent-jackets (qv.). Chain-stents consist of a
serial formation or train of individual stents, or substents
(sub-stents), each connected to the next at either end with those
at the end of the formation connected at only one end. Chain-stents
allow stenting that spans across (skips over, straddles) segments
of ductus that curve or flex with body movement, or do not require
or should not be stented, or which have attachments or adhesions
that should not be dissected. Articulated chain-stents connect the
substents by means of fine nonmagnetic wires so that the interval
separating the substents can be different and each chosen for the
segment which that substent is to encircle. Segmented chain-stents
are cut or molded into a continuous length of polymeric tubing at
various but regular intervals with a connecting or bridging strip
running the entire length of the chain along one side. Any number
of consecutive substents can be snipped off for use, and except for
the continuous connecting strip, which can be left intact to impart
greater resistance to migration, segments to be omitted can be
snipped away; sectional stent-jacket, serial stent. Cf. mixed
chain-stent.
[5207] Charge--The magnetically susceptible bound or encapsulated
pharmaceutical or load or its delivery to an impasse-jacket,
leaving it charged or loaded; load.
[5208] [Airgun] chassis--The cabinet containing the propulsive and
control means for turning a barrel-assembly into the barrel of an
interventional airgun when the barrel-assembly is inserted
therein.
[5209] Clamp-collar--A round clamp at the rear or proximal end of
the turret-motor for securing the end of the barrel-catheter.
[5210] Clasp-magnet--A permanent magnet encapsulated within a
chemically isolating envelope of plastic or metal and mounted on a
base with prongs for engagement into the muscle fascia or pleura;
patch-magnet.
[5211] Clasp-patch--A bandage consisting of a spandex or similar
elastic backing having ferromagnetic clasps as points for
undercutting the subjacent surface tissue, whether organ capsular,
fibrosal, adventitial, or pericardial, or fascial. Conceptually, it
is the counterpart to a patch-magnet (clasp-magnet); in that it
provides the attracted as opposed to the attracting component. Cf.
clasp-wrap.
[5212] Clasp-wrap--A wrap-surround (qv.) or bandage consisting of a
spandex or similar elastic backing having ferromagnetic clasps with
points for undercutting surface tissue, such as organ capsular,
fibrosal or adventitial tunical, or pericardial. Patches not
intended to wrap around a ductus but rather fasten to subjacent
tissue are clasp-patches. The points are arranged in an opposing
formation or formations to undercut the fibrosa or adventitia, for
example. A clasp-wrap can sometimes be used when the ductus would
not retain separate ductus-intramural implants or would not do so
quickly enough. Once placed, a stent-jacket or patch-magnets are
used as the extravascular (circumductal, periductal,
circumvascular, perivascular) component of a stent, for example.
The clasps are given a deep outer texture, a perforation, and may
be wetted with a solution to encourage tissue infiltration for
long-term retention. The internal surface of the backing may be
coated with an elastic adhesive; however, an adhesive is limited to
serving as an interim measure to bridge the period during which
tissue infiltration and adhesion develop. As a prosthetic outer
layer or tunic, it may be considered intravascular or intraductal;
clasp wrap-surround, clasp-bandage, clasp-jacket. Cf.
clasp-patch.
[5213] Close-ended--Said of a cooling catheter or cooling capillary
catheter having side-holes but closed off at the distal end for
delivering cooling air or gas or heating air to the adjacent tissue
or components. A cooling catheter for cooling an adhesive to extend
its open time can have both side holes and a small hole at the
distal end. Unrelated to close-backed as designating an nonpiped
radial projection unit.
[5214] Combination-form--An ablation or ablation and
angioplasty-capable barrel-assembly (qv.) or a radial projection
catheter (qv.) with a central channel (bore, passageway) through
which a prior art cabled device or devices such as a fiberoptic
endoscope, laser, or rotational atherectomy, thrombectomy cutter,
or similar device can be passed. A proximally (extracorporeally,
extraductally) placed side-port (qv.) leading to the central
channel through a frontomedially directed tunnel-tube allows a
cabled device or devices to be inserted into and through the bore
and up to or through the nose or distal end. When the central
channel is at least partially empty, distally (intracorporeally,
endovascularly) placed side-ports, or side holes, leading to the
central channel through frontomedially directed tunnel-tubes allow
blood to pass through the central channel between the front end or
nose and the side-port; through-bored.
[5215] Combination-form barrel-assembly--A barrel-assembly (qv.)
that accommodates commercial cabled devices, such as a laser,
endoscope, thrombectomy, or atherectomy cutter, along its central
axis to its distal end as central component. Interchangeability of
such devices imparts greater versatility to the barrel-assembly in
allowing different views and procedures during the course of a
single entry endoluminal procedure as well as in expanding the zone
of applicability to different operations. When augmented thus, a
barrel-assembly with a peripheral component (qv.), or radial
projection system (qv.), is increased in ablation or angioplasty
capability. To afford a channel for the central component, such a
barrel-assembly, referred to as a combination-form ablation or
ablation and angioplasty-capable barrel-assembly, requires the use
of an edge discharge muzzle-head (qv.); through-bore
barrel-assembly. Cf bipartite ablation or ablation and
angioplasty-capable barrel-assembly.
[5216] Combination-form muzzle-head--The edge-discharge muzzle-head
(qv.) in a combination-form barrel-assembly; through-bore
muzzle-head.
[5217] Combination-form radial projection catheter--A sheath
(sleeve, tube) without a ballistic component (barrel-tube) that
incorporates one or more electrical and or fluid radial projection
systems (qv.) and includes a central (longitudinal axial) channel
for installing a permanent cabled device or for accepting
interchangeable commercial cabled devices, such as an endoscope or
laser. When this device is a laser or atherectomy cutter, the
ablation or ablation and angioplasty-capability of the device is
enhanced; however, since tool-inserts (qv.) are interchangeable,
any radial projection catheter (qv.) is ablation and/or
angioplasty-capable. Inserting a simple pipe or radial discharge
barrel-assembly in the central channel yields a barrel-assembly
with ballistic and peripheral components (qv.) where the central
component has been displaced by the ballistic component. To obtain
optimal functionality from an ablation or ablation and
angioplasty-capable barrel-assembly and a combination-form radial
projection catheter as independent when the two are used together,
these are made as a matching set for a given gauge. The power and
control housing of the barrel-assembly is disconnected and the
radial projection catheter slid over the barrel-catheter of the
barrel-assembly and the power and control housing of the
barrel-assembly reconnected so that the housings stand in ganged
relation; through-bore radial projection catheter. Cf. Radial
projection catheter, bipartite ablation or ablation and
angioplasty-capable barrel-assembly, power and control housing.
[5218] Complete stent-jacket--A full-round stent-jacket (qv.) with
side-slit rather than a side-slot to clear an anatomical
attachment.
[5219] Compound impasse-jacket--A braced (qv.) impasse-jacket with
more than one dummy-collar, or outrigger, at either end of a
singular magnetized Impasse-jacket at the center or a double
impasse-jacket, which includes more than one magnetized
impasse-jacket rigidly fastened end to end by bendable bridging
arms to allow straddling over or spanning intervening segments
which flex, are severely malacotic, or should remain attached to
neighboring tissue. Compound and chain impasse-jackets are
inhrerently braced (qv.) without the need for unmagnetized
dummy-collars at one or both ends. A compound impasse-jacket is the
same in structure regardless of whether a given constituent jacket
is used as a trap (qv.) or holding jacket (qv.). When one jacket is
used to hold and the other to trap miniballs, the jacket is mixed
or composite; double impasse-jacket.
[5220] Compound-guard [miniball] impasse-jacket--A double
impasse-jacket (qv.) with two magnetized jackets where both are
used to stop any miniball or miniballs that might originate
upstream. The need for more than one guard or trap-jacket indicates
that more miniballs are to be protected against than the first
jacket could stop without becoming occluded. The strength of
magnetization of the first jacket is accordingly adjusted so that
the pressure exerted the lumen contents when obstruction would
occur is sufficient to force the miniball or miniballs at the
center forward to the next trap-jacket. This pattern of graduated
field strength in the direction of flow is iterated in a chain
trap-jacket; compound trap-jacket; double guard impasse-jacket.
[5221] Compound [miniball] holding jacket--An impasse-jacket (qv.)
that includes two magnetized jackets to hold medication or
radiation-emitting miniballs suspended in the lumen.
Impasse-jackets that include more than two holding jackets as
double are chain holding jackets that are triple, quadruple, and so
on. Where compound-guard impasse-jackets are implanted empty,
holding jackets are loaded with the miniball or miniballs to be
held, by injection at the bridge (qv.) through the same access
portal; double holding impasse-jacket.
[5222] Compound mechanical tool-insert--A tool-insert (qv.) that
when its tip is brought into contact with the lumen wall is
actuated by internal means, usually a spring. Contract with the
lumen wall is usually produced by the raising of the tool-insert by
the tool-insert holding and lift platform, and discharge typically
involves the release of an injectant into the wall.
[5223] Compound mechanical-electrical tool-insert--A tool-insert
(qv.) that is both lifted into contact with the lumen wall and
discharged by internal means rather than by the tool-insert holding
and lift platform (qv.), usually through the generation of a gas by
allowing chemicals to mix that had been kept separate by an
intervening barrier or wall such as of wax until melted by the flow
of current in an electrical heating filament coursing through this
separating barrier. When the flow of current is initiated
automatically or locally without the need to use a switch, the
outer tip of the tool-insert, which is a spring-loaded contact of a
switch, must be close enough to the surface so that when pressed
against the lumen wall, the tip is pressed downward (toward the
floor of the tool-insert holding and lift-shaft) bringing it into
contact with the other contact and thus closing the circuit.
[5224] Compound tubing--highly pliant polymeric tubing lined with a
thin layer of polytetrafluoroethylene approved for medical use;
co-extruded tubing; a coextrusion.
[5225] [Barrel-assemblly power and] Control housing--The part of an
ablation or ablation and angioplasty-capable barrel-assembly or a
radial projection catheter containing the battery or batteries,
control electronics, and having a control panel mounted on its
upper surface for ease of view and use with either hand. For ease
of manipulation, it is generally configured as, or to include, a
pistol grip. To obtain optimal functionality from an ablation or
ablation and angioplasty-capable barrel-assembly and a through-bore
or combination-form radial projection catheter as independent so
that the two can be used together, these are made as a matching set
for a given gauge. With the control housing of the barrel-assembly
disconnected, the barrel-assembly is a minimally capable ablation
or angioplasy barrel-assembly. The radial projection catheter can
then be slid over the barrel-catheter of the barrel-assembly and
the power and control housing of the barrel-assembly reconnected so
that the housings stand in ganged relation. For trackability, the
barrel-assembly is introduced first, and the radial projection
catheter is then slid over its barrel-catheter as a kind of guide
wire after the muzzle-head has been moved to the treatment site.
Further to enhance trackability, the muzzle-head can emit a
lubricant for use with the oscillatory mode of the turret-motor;
battery pack and control housing [with hand-grip], control box. A
universal power and control housing that can be used with any
barrel-assembly requires controls for every function and limited to
use with only one at a time.
[5226] Control panel--1. The positioning and discharge set of
controls mounted to the airgun or 2. The ablation and atherectomy
set of controls mounted on-board an ablation or ablation and
angioplasty-capable barrel-assembly (qv.); barrel-assembly control
panel. Cf. [Barrel-assemblly power and] Control housing.
[5227] Cooling rod or catheter--1. A prewarmed or chilled solid rod
or a tube (conduit) that is prepositioned or is passed down the
central canal (qv.) of a barrel-assembly (qv.) barrel-tube (qv.),
central canal (qv.), or central channel (qv.) or down the central
canal or channel in a special radial projection catheter (qv.) for
altering the temperature of the components therein. 2. A tube
mounted alongside an adhesive delivery line inmate or attached to a
stay insertion tool (qv.) for conducting cold air or gas or hot air
to the tissue adhesive, the tissue treated, or parts of the
apparatus itself. A cooling catheter of a caliber to allow
insertion into a small barrel-tube is referred to as a capillary
cooling rod or catheter. Where no barrier would prevent the entry
of heating or chilling fluid into the bloodstream, the cooling
catheter must be closed-ended or a solid rod. To restrict the
temperature change to a preferred segment of the lumen wall, the
wall of a tubular cooling catheter can be perforated over only a
certain segment along the length. A cooling catheter miming down
the center or alongside an adhesive delivery line attached to a
stay insertion tool has side-holes, while one attached to cool the
ductus is open at the distal end. Cf. service catheter.
[5228] Cooling [capillary] catheter--A tube with a chamfered or
conical front (distal) closed end and side-holes over the distal
segment, which is positioned alongside or just short of the
recovery electromagnets, radial projection unit brush-type
tool-inserts, and turret-motor when fully inserted into the central
canal of a center-discharge or the barrel-tube of a center or
edge-discharge barrel-assembly. The appellation `capillary`
pertains to cooling catheters for passing down a barrel-tube, which
must be very small in diameter. To quickly return the heated
components to body temperature, vortex tube-generated cold air is
passed through the side-holes of the cooling catheter; rapid
cooling catheter; chilling catheter.
[5229] Cooling catheter insertion channel--A passage cut along the
central axis proximal to the recovery electromagnets in a
center-discharge muzzle-head ejection head for acceptance of the
distal end of a cooling catheter.
[5230] Composite barrel-assembly--Same as bipartite barrel-assembly
(qv.); duplex barrel-assembly.
[5231] Discharge set--A plurality of successive discharges
belonging to a discrete sequence or group unit directed at a
specific segment or lesion along the lumen. With a multiple barrel
barrel-assembly, each discharge may implant multiple miniballs;
discharge group; discharge sequence.
[5232] Discharge stack--An instruction stack that coordinates a.
The two drivers consisting of open-loop controlled stepper motor
operating the linear positioning table for transluminal movement
and the closed-loop controlled dc servomotor that rotates the
muzzle-head with b. Actuation of the airgun undamped direct current
powered plunger solenoid (used as a hammer to strike the valve body
pin) through the program sequencer and servocontroller in order to
execute a preset discharge pattern.
[5233] Distal--Farther from the operator than the point of
reference.
[5234] Double wedge insert lining--An insert lining for a temporary
shield-jacket (qv.) or a prepositioned spaced apart magnet-type
base-tube (qv.), or an intrinsically (qv.) or quasi-intrinsically
magnetized (qv.) stent-jacket (qv.) consisting of complementarily
inclined layers joined at a distolaterally inclined plane. The
inner wedge of moisture barrier-coated viscoelastic polyurethane
foam protects the adventitia and dissipates momentum of the
miniball, while the outer of a resilient nonallergenic rubbery
elastic material redirects the miniball to a trajectory less
inclined toward the lumen to a functional subadvential or medial
location; cf. bounce-wedge, foam-wedge.
[5235] Ductus-intramural--Within the wall of a ductus;
ductus-intraparietal.
[5236] [Impasse-jacket] Ductus-transverse displacement--Sudden
downward thrust, usually of an artery, against subjacent tissue
under the repulsion of an external miniball extraction
electromagnet (qv.) used to noninvasively extract a miniball from
the lumen of the artery and through the mesh of the impasse-jacket
(qv.) encircling it. Such can occur when the ductus does not lie
flat against subjacent tissue that extends beyond the end-edges of
the impasse-jacket and that tissue is not sufficiently firm to
cushion the thrust. An artery that overlies a space, soft tissue,
or lies superjacent at a distance to hard tissue and experiences a
sudden thrust can be injured by flexion and stretching at the
end-edges or margins of the impasse-jacket prompting medial and
intimal hyperplasia, restenosis, and the need for reperfusion.
Potentially injurious displacement is averted by elongating and
thus positionally stabilizing the jacket. A simple jacket (qv.) can
be elongated, or if an intervening segment must be spanned across
(skipped, straddled), then a braced (qv.) or compound (qv.)
impasse-jacket is used, and if multiple segments must be spanned
across, then a chained impasse-jacket (qv.) is used. If necessary,
the jacket is additionally tied down by looping suture around mesh
strands over the end-cuffs (qv.) of the jacket and any unmagnetized
dummy-collars or outriggers (qv.) and tying the ends thereof to
neighboring, usually subjacent tissue of sufficient strength under
a pulling force suffcient to close the gap but not interfere with
pulse compliance; ductus thrust, ductus-normal displacement,
extraction-thrust; repulsion-normal displacement. Cf.
margin-levering, chain-guard, braced impasse-jacket, compound
impasse-jacket, chain impasse-jacket.
[5237] [Impasse-jacket] Dummy-collar--An unmagnetized
impasse-jacket (qv.) outrigger (qv.). A braced entry-collar is a
dummy-collar used when necessary to minimize levering of the
impasse-jacket. A braced exit-collar may serve this purpose and be
magnetized to take up any magnetic carrier bonded drug to be
stopped from passing the impasse-jacket. Since it is magnetized, it
is not a dummy-collar but an impasse-jacket outrigger, which can be
an unmagnetized or dummy-collar or magnetized.
[5238] Duplex barrel-assembly--Same as bipartite barrel-assembly
(qv.); composite barrel-assembly.
[5239] Edge discharge barrel-assembly--A barrel-assembly having a
burr or laser atherectomy cable running down its center, so that a
central canal is unavailable for use as a portion of the peribarrel
space that in a center-discharge barrel-assembly (qv.) can be used
to insert a cooling capillary catheter (qv.) past the turret-motor
(qv.) and into the ejection-head to cool these components when used
as heating elements for thermal angioplasty; combination-form
barrel-assembly, through-bore barrel-assembly.
[5240] Edge discharge muzzle-head--The muzzle-head (qv.) in an edge
discharge (combination-form, through-bore) barrel-assembly (qv.)
wherein the axial center is occupied by an atherectomy burr or
laser cable; combination-form muzzle-head, through-bore
muzzle-head.
[5241] [Muzzle-head] Ejection head--The solid nonmagnetic metal
distal or front portion of the muzzle-head (qv.), which accepts and
fixes in position the distal ends of the barrel-tubes.
[5242] Ejection tool-insert--An emitter (qv.) type radial
projection unit (qv.) tool-insert (qv.) for releasing fluid into
the lumen rather than injecting it into the lumen wall. The
self-contained syringe type can be used in either an electrically
or a fluidically operated system, but is limited to the amount and
type of fluid it contains. By contrast, a fludically operated
flow-through (qv.) ejector fed from one or more reservoirs outside
the barrel-assembly is not so limited. Interchangeable and/or
switchable reservoir refill cartridges allow a wholly contained
fluid system in an ablation or ablation and angioplasty-capable
barrel-assembly to provide any number of fluids in any amount and
sequence. Unlike injectors (qv.), ejectors are usually not raised
and lowered but instead kept flush to the surface of the
muzzle-head by a gap that separates the base of the ejector from
the lifting mechanism; ejection syringe tool-insert; ejector Cf.
emitter, electrical ejector, fluid system ejector, flow-through
ejector, injector, electrical injector, fluid system injector,
electrical tool-insert, fluid tool-insert, flow-through
injector.
[5243] Electrical emitter--A syringe-type noninjecting ejector or
injecting injector tool-insert (qv.) that is electrically connected
when inserted into the lift-platform (qv.) of a radial projection
unit (qv.). It is used in a fluid or piped system when the
injectant is other than that passing through the line. The
electrical connection allows the contents to be heated until used.
Cf. ejector, electrical ejector, fluid system ejector,
injector.
[5244] Electrical injector--A syringe-type self-contained injection
tool-insert (qv.) containing a heating element that is electrically
connected when inserted into the lift-platform (qv.) of a radial
projection unit (qv.). It is not usable in a fluid or piped system.
When an injectant other than that passing through the line is to be
delivered, a nonelectrical syringe injector is used and the
temperature controlled by passing temperature-adjusted fluid
through the fluid line. Injectors and lines can be insulated. In an
electrically operated radial projection system (qv.), the
electrical connection allows contents such as protein solder,
surgical cement, a tumefacient, vasodilator, or other medication to
be heated until used. Cf. emitter, ejector, electrical ejector,
fluid system ejector, injector. Emitter [tool-insert]--A
tool-insert (qv.) that is used to eject or inject a fluid. An
ejector has perforations in a flat working face for releasing fluid
medication into the lumen at the treatment site, whereas an
injector delivers a fluid into the lumen wall through a hollow
needle or needles. A self-contained syringe type tool-insert
emitter can deliver no more fluid than it can hold. If connected
electrically, the emitter can heat the fluid to a preferred
temperature. An ejector can be insulated and/or positioned
stationary as flush to the surface of the muzzle-head or retracted
to more quickly remove the heat or cold, and lowering the emitter
to a barrel-tube containing a cooling catheter further accelerates
cooling. A fluid system flow-through (qv.) type emitter (qv.)
affords greater capability in administering fluids, because an
unlimited amount and any number of different fluids can be
delivered quickly at the temperature desired. The temperature is,
moreover, quickly adjusted by changing the temperature of the fluid
in the line; ejector, injector. Cf. electrical ejector, fluid
system ejector, flow-through (qv.) ejector, injector, electrical
injector, fluid system injector, electrical tool-insert, fluid
tool-insert, flow-through emitter.
[5245] Electrical tool-insert--A tool-insert for use in an
electrical radial projection system (qv.). Engaging the projection
that extends down from the center bottom of the base into the
socket on the lift-platform also connects the tool-insert
electrically. The electrical connection can be used to warm the
contents of a syringe ejector (qv.) or injector (qv.) or power a
motor inside the tool-insert. Fluid operated radial projection
systems are generally not provided with a source of electrical
power and cannot accept electrical tool-inserts. Cf. emission
tool-insert, injector.
[5246] Emission tool-insert--An ejection tool-insert or ejector
(qv.) or an injection tool-insert or injector (qv.); emitter.
[5247] Emitting pressure--In a fluidic radial projection unit (qv.)
circuit, that line pressure greater than the idle pressure (qv.),
then the lifting pressure (qv.), that forces an emitting
tool-insert to release fluid, or discharge; the reciprocal of the
aspirating or intake pressure (qv.). The term is pertinent to
antegrade (forward) or actuating flow, the term intake pressure
pertaining to retrograde (reverse) or aspirative flow.
[5248] Since each tool-insert can be made to discharge at a
different pressure, this factor pertains to the individual
tool-insert. The emitting pressure is equal to the idle pressure
plus the additional pressure necessary to raise the lift-platform,
or the lifting pressure, plus any additional pressure that is
necessary to cause the individual tool-insert to discharge.
[5249] End-cap--In a barrel-assembly (qv.), a plate at the distal
end of the barrel-assembly but which will almost always be attached
to the proximal end of the spindle neck (qv.) that is excluded in
most embodiments. In a supporting arm and connecting cable used to
connect an auxiliary syringe (qv.) frame or holder to a stay
insertion tool (qv.) for independent or coordinated operation, the
conductor positioning covers at the ends of the connecting
cable.
[5250] [Impasse-jacket] End-cuffs--Linings of viscoelastic, usually
polyurethane, moisture barrier-coated viscoelastic polyurethane
foam at the ends of impasse-jackets (qv.) and any dummy-collars or
outriggers (qv.). End-cuffs provide 1. End-cushioning and a gap
between the adventitia and the jacket mesh that protects against
adventitial, vasa and nervi vasoral incisions by the wires of the
mesh, 2. Some latitude in caliber of the impasse-jacket required
for a specific segment, thus a. Eliminating the need to produce
jackets in many intervening calibers, and b. Saving much
midprocedural time to obtain a good fit for unrestricted compliance
with the pulse or intrinsic muscle action, and 3. A space to allow
suture to be looped over or beside a mesh strand above the end-cuff
to allow the use of tie-downs (qv.) if necessary.
[5251] End-implant--A corrective or prosthetic device, such as a
magnetic stent-jacket (qv.), which is left in place after
withdrawal and closure. Opposed to a device such as a perforation
shield-jacket (qv.) that is placed temporarily to prevent a
perforation during discharge and removed before closure. Implants
completely or partially absorbed after closure, such as radiation
shield-jackets, are nonpermanent end-implants. Cf. temporary
implant.
[5252] End of segment--The distal or downstream level for ending
exposure of the delimited or defined length (segment) of the ductus
upstream (proximal) thereto to the action of the drug,
radionuclide, and/or other therapeutic substance released at the
start of segment (qv.). An an exit impasse-jacket, or exit jacket
(qv.), is used when uptake of the drug within the segment is
subtotal and the residue is to be eliminated. The inactivating
substance is released from a time-released miniball whether the
result of dissolution of its shell or the miniball itself, which
releases a ferrofluid or microspheres that release magnetically
susceptible drug carrying nanoparticles in turn. Miniball or
microsphere dissolution can be initiated by heating an entry or
exit-jacket, or through the use of a miniball that is a
`smart-pill," so that once ingested, it delivers medication
according to its programmed responses to the conditions it
encounters. The inactivating substance may combine with or cleave
the active drug molecule with or without the addition of another
substance and/or the application of heat. The release of an
inactivant-activating substance from the entry or at the exit
jacket or the inactivating substance from the exit jacket can be
triggered by a third substance and/or heating. Release at the exit
jacket is usually simulataneous with release at the entry-jacket.
Cf. start of segment.
[5253] End-pivot--A joint that allows the working end of a stay
insertion tool (qv.) to be tilted so that the handle can be at an
angle; allowing a longer segment of a ductus to be treated through
a small entry incision; tilt-end, tilt-pivot, pivot-base,
base-pivot, pivot-end.
[5254] Endoluminal approach--Approach to the wall of the ductus
from inside the lumen; the approach used to inserts miniballs.
Approach thus calls for endoluminal in situ testing. Cf.
extraluminal approach.
[5255] End-plate--The proximal terminus of the barrel-assembly when
connection to the airgun power supply is made by engagement in the
airgun chamber. It is not only a compound plug but a terminal
centering device.
[5256] Endothelial breakaway--The ability of a muzzle-head (qv.) to
move without clinging to or seizing against the interior of the
lumen. Sufficient lubricity and avoidance of a muzzle-head that is
too large in diameter for the lumen minimize entrapment by
adherence. A lubricant can be delivered to the stuck muzzle-head
through a service-channel (qv.). In more elaborate embodiments, the
muzzle-head can also be oscillated to work it loose.
[5257] End port--A fluid connector in an end-socket (qv.), that is,
in the end- or terminal plate (qv.) of the barrel-assembly that
allows connection of an external source of pressurized fluid to a
barrel-tube (qv.) in a barrel-assembly (qv.) or to a fluid radial
projection circuit (qv.) in a radial projection catheter (qv.) for
discharge into the lumen.
[5258] End-socket--A socket in the end-plate (qv.) when used to
connect external devices. It can include electrical, fluid, or both
types of connectors; end connector.
[5259] End-stent--The first or last stent in a chain-stent (qv.).
Cf. chain-stent, articulated and segmented stent-jacket.
[5260] End straps--Ductus binding (girding, cinching)
anti-migration straps (qv.) when fastened to and extending from the
end interconnecting extension-tabs on a segmented-type sectional or
chain-stent, so that the ductus itself and not the jacket is girded
about, thus requiring a lining of expansion jointed moisture
barrier-coated viscoelastic polyurethane foam sometimes faced in
gauze to protect the adventitia; except midprocedurally, suture is
not wound around a ductus. Side-straps (qv.) do not require such a
lining. Wider end-straps are perforated to allow the surface of the
ductus to `breath ` and engage in ion exchange. End-straps and
side-straps are singular (one-sided) or two-sided toward either end
of the jacket according to the difficulty of use, whereas end-ties
(qv.) are usually one-sided. These are added to the individual or
segmented jacket based upon the application, allowing jacket
standardization and reduced cost. Cf. side-straps, end-ties.
[5261] End-tabs--The outrigger (qv.) cuffs or collars used to
secure end-ties(qv.). The antilevering outriggers used with
impasse-jackets (qv.) are not made of suture but rather stiff metal
braced. End-tabs assist to prevent migration along the ductus, but
do not extend anti-levering stabilization to the outer margins of
the outriggers as do the outriggers of impasse-jackets.
[5262] End-ties--Anti-migration tethers usually used when
circumvascular clearance would result in the abrasion, erosion, or
fistulization of neighboring tissue or to add further stabilization
to a stent-jacket or impasse-jacket positioned in a location of
pronounced movement. End-ties consist of strong woven suture,
passed through or prefastened to an eyelet or wrapped about and
knotted beneath the head of a wide head rivet toward the ends of
the jacket, or in a magnet-jacket, tabs sewn onto the jacket, that
extend off to either side of the jacket to gird about the ductus.
The girding end-tabs have hook and loop fasteners with a backing of
spandex and an internal or ductus contacting surface of
expansion-jointed moisture barrier-coated viscoelastic polyurethane
foam and if additional resistance to sliding along the ductus is
needed, a facing of gauze. The suture is fastened to end-tabs in
the same way as it is fastened to the jacket. If greater resistance
to sidewise sliding along the ductus is desired, the moisture
barrier-coated viscoelastic polyurethane foam is faced with gauze
to impart some ribbing. End-tie end-tab type outriggers (qv.) are
end-anchors tethered by suture that serve to resist migration along
the ductus and can do so about a point of flexion, for example,
whereas impasse-jacket type outriggers are metal bridged, or
hard-braced, end-anchors that serve primarily to resist levering of
the impasse-jacket in an extraction and secondarily its migration.
End-ties can unilateral or bilateral; end-belts, shackles. Cf.
side-straps, end-straps.
[5263] [Radial projection] End-unit--An electrically or fluidically
operated radial projection unit (qv.) with its own electrical or
fluid pipeline, making it independently controllable. Whereas
nonpiped (electrical) units are projectable, piped units can be
projectable or unprojectable.
[5264] Endoluminal approach--Approach to the wall of the ductus
from inside the adventitia; the approach used to implant
miniballs.
[5265] [Stay] Entry incision--The cut made through the adventitia
or fibrosa by the stay as it enters into the wall of the ductus.
Term used to distinguish this intracorporeal incision from the
incision or trocar puncture used to access the ductus from outside
the body, which latter is referred to as the entry wound (qv.).
[5266] [Impasse-jacket] Entry collar--An unmagnetized or
dummy-collar braced to the entry end of an Impasse-jacket to
minimize levering of the impasse-jacket. A corresponding
exit-collar if magnetized is by definition not a dummy-collar but
an impasse-jacket outrigger (qv.), which term applies to
impasse-jacket braced side-collars whether magnetized.
[5267] [Miniball] Entry- [impasse- or stent-] jacket--A holding
jacket (qv.) encircling a treated ductus, usually a blood vessel,
at the start of segment (qv.) identified for differential treatment
or at the inlet to a target organ. When targeting is not inherent
or physiological, as is iodine to the thyroid gland, confinement to
the targeted segment or organ is achieved by binding the
therapeutic agent to magnetically susceptible drug and/or
radionuclide carrier particles or nanoparticles. A jacket upstream
from the start of segment to release a drug activating agent, for
example, is not at the start of segment and is not an entry-jacket.
Magnetic drug carriers also allow the use of an externally
generated radio frequency alternating magnetic field to heat the
particles and thus increase the rates of dissolution and uptake,
further concentrating the dose beyond what could be prescribed
systemically. The jacket can be loaded by injection, infusion, or
ingestion of a drug and/or radionuclide magnetic carrier
nanoparticle ferrofluid, or in the form of miniballs or
microspheres that by dissolving in the bloodstream, affected a by
the introduction of a followup agent, and under magnetic traction
release the therapeutic substance. The miniball or
microsphere-contained agent may be formulated for release at the
entry jacket only upon exposed to another substance that serves as
a solvent, affording dose and timing control, which is ingested or
injected or infused upstream. Locally released and inactivatd, the
agent can be applied in a higher concentration than were it
delivered through the systemic circulation. To pass through the
jacket, the residue must be either magnetically nonsusceptible or
not so susceptible that the propulsive force of the contents does
not overcome the magnetic attraction of the jacket. Unless this
force is excessive (such as might occur in rare cases of malignant
hypertension, for example), or magnetic uptake by the intervening
jacket or jackets is deficient, little of the active drug should
continue past the end of segment (qv.) as to require the use of a
preplaced exit-jacket (qv.) to release a drug inactivating or
neutralizing agent; inflow-jacket, inlet-jacket. Cf. [Miniball]
exit- [impasse-] jacket, start of segment.
[5268] [Stay] Entry wound--An incision or trocar puncture, usually
laparoscopic or `keyhole` sized, made to access the ductus from
outside the body. Term used in contradistinction to the following
incision made through the outer layer (tunica adventitia, tunica
fibrosa) of the ductus by the stay as it is inserted or injected
subadventitially or medially by the stay insertion tool (qv.),
which latter is referred to as the stay insertion incision or stay
injection incision (qv.). Pretesting, stay injection, and
stent-jacket insertion are all through the same entry wound. A
single incision will usually allow the leading end of the
stent-jacket (qv.), of which the internal surface will usually have
been lubricated, to be inserted and expanded about the ductus to
achieve circumvascular placement. A longer stent-jacket may require
a second incision over the distal end point to secure the distal
end-tie of a magnetic stent-jacket or the distal belt-strap (qv.)
of a nonmagnetic stent-jacket.
[5269] Esophageal tacking--The support of a collapsed tracheal
ceiling by attraction to magnets retained along ventrolateral lines
within a magnet-wrap (qv.) placed parallel to the segment of
trachea affected about the esophagus; magnetic esophageal
tracheopexy.
[5270] Exit-coating feature--In a stay insertion too (qv.)1, a
miniature pump line with terminus positioned over the point of stay
ejection to allow stays to be coated with a semiliquid
substance.
[5271] [Miniball, microsphere, or ferrofluid] Exit- [impasse- or
stent-] jacket--A holding jacket (qv.) placed to encircle a ductus
at the terminus of a drug and/or radionuclide-targeted segment
(length) or at the outflow of a target organ. For treatment within
the lumen, the drug and/or radionuclide is ferrobound (qv.) and can
be delivered as a ferrofluid. For treatment of an organ, it is
separable from the magnetic vehicle or ferro co-bound (qv.) by, for
example, containment within microspheres (qv.) or miniballs (qv.)
that also contain ferrous content or are contained within a shell
(casing, outer coat) containing ferrous content. Whether infused,
injected, or swallowed, ferrobound agents are used in ductus to
draw the medicinal component against and/or into the lumen wall
under the tractive force of a first or entry holding magnetic
extraluminal stent or impasse-jacket (qv.), whereas in co-bound
agents, only the magnetically susceptible component is drawn to the
magnetized jacket, the co-bound drug and/or radionuclide freed to
flow downstream when the shell containing both is disintegrated by
dissolution, chemical cleavage or binding by another agent,
magnetic traction, and/or the application of heat. The medicinal
agent released at the entry-jacket, that is, at the start of the
segment or inflow to an organ is taken up by the targeted tissue.
An exit jacket is only needed when a medicinal and/or radioactive
component must be limited to the target segment or organ, uptake by
the target is incomplete, and dilution upon passing the target,
such as into the general circulation, is insufficient.
Neutralization of the agent released upstream can be by heating the
exit jacket in an alternating magnetic field and/or binding,
cleaving, or other action by an agent or agents released from the
exit jacket with or without heat. The agent is thus magnetically
held and released by one or more of the foregoing means at the
entry jacket as starting point and destroyed by heat or by the
relase of a neutalizing agent at the exit-jacket as ending point.
Cf. [Miniball, microsphere, or ferrofluid] entry- [impasse-]
jacket.
[5272] Exit-hole--The aperture through which the miniball is
ejected; exit-port, muzzle-head port, muzzleport. The term `muzzle`
is not used to avoid confusion with the muzzle of the airgun.
[5273] Exit velocity--The instantaneous velocity of the miniball
upon discharge at the muzzle-port (qv.); the muzzle velocity upon
ejection from the muzzle-head. The term is necessitated by the fact
that the barrel-assembly muzzle-head and original muzzle are
different parts; insertion of a barrel-assembly into the airgun
barrel extends the point of exit distad from the original muzzle;
discharge velocity.
[5274] [Stent-jacket] Expansion insert--An arcuate segment of
absorbable or percutaneous ultrasonic lithotriptor-destructible
material applied to an edge of a stent-jacket side-slit or
side-slot to allow the stent-jacket to gradually decrease in
diameter as an originally enlarged condition of the substrate
ductus subsides; stent-insert; stent-insert.
[5275] Expansion slit--The cut-line along the side of a
stent-jacket (qv.) that providing free edges, allows compliance of
the elastic base-tube (qv.) with movement in the wall of the vessel
or duct; side-slit. Cf expansion-slot, side-slot.
[5276] Expansion-slot--The longitudinal gap along the side of a
stent-jacket (qv.) that providing free edges, allows compliance of
the elastic base-tube (qv.) with movement in the wall of the vessel
or duct; side-gap.
[5277] Expansion-strip--One of several bands (strips, lengths) each
made of a different polymeric or stoney material cut to the same
length, which are supplied with a stent-jacket (qv.). The polymeric
strips have a different absorption rate, while those of stone allow
disintegration upon demand by lithotripsy. The strips can be
cemented alone or in any combination to the edge or edges of the
stent-jacket (qv.) base-tube (qv.) side-slit (qv.) or side-slot
(qv.) in order of absorption time with the strip at the open edge
breaking down first, and so on. When the ductus treated is swollen
and the rate of subsidence is reasonably predictable, absorbable
strips allow the side-slit or side-slot to be expanded for gradual
subsidence in reasonable pace with the ductus, whereas when
disintegration is to be subject to direct control based upon
imaging, stoney strips allow disintegration by lithotripsy.
[5278] Extended adjustment stent-jacket--A stent-jacket (qv.) with
a stent expansion insert that includes constituents that take a
longer time to be absorbed or require deliberate action, such as
the use of a lithotriptor, to break down; extended contraction-time
stent-jacket, adjustment stent-jacket.
[5279] Extraction electromagnet--A powerful extracorporeal
electromagnet used to withdraw a miniball trapped or held within an
impasse-jacket through the wall of the ductus and a hole in the
mesh thereof to a safe location outside the ductus or entirely
outside the body. A method for adapting a nuclear magnetic
resonance imaging machine for this purpose even when the miniball
is lodged behind bone, a tendon, ligament, or aponeurosis is
described in section X2c entitled Stereotactic Arrest and
Extraction of a Circulating, Dangerously Mispositioned, or
Embolizing Miniball. The field strength is usually set to allow the
magnet to be briefly pulsed, thereby extracting the miniball in a
controlled incremental manner; however, when the miniball lies
behind hard tissue, the field force required may result in
extraction entirely outside the body.
[5280] Extraction grid--The open mesh or grating-surround of an
impasse-jacket that allows the use of an external (extracorporeal)
extraction electromagnet to noninvasively extract miniballs
suspended in the jacketed lumen through the ductus wall and the
mesh to a safe location outside the ductus. Depending upon the
strength of magnetization required, a nonabsorbable grid may
consist of intrinsically magnetized stainless steel or a metal cage
overlain with a neodymium iron boron grain impregrated polymer or
copolymer, for example. A nonabsorbable impasse-jacket or one with
an absorption period longer than the time to depletion of a high
dose rate emitting seed miniball it is to suspend may include an
absorbable radiation shield of less persistence than the extraction
grid. Since an absorbable extraction grid must withstand the force
exerted by the external magnet, unless it has been primed for
dissolution on demand, it must not commence disintegrating for a
period following extraction. Dissolution on demand is usually
effected by heat induction of embedded ferrous granules that melts
its matrix and/or releases a solvent to accelerate dissolution.
[5281] Extraction [field] intensity; extraction field strength--the
magnetic field strength used to remove a miniball that had been
misplaced upon implantion.
[5282] Extraction perforation--The passage torn through the wall of
a ductus and additional tissue by the forcible extraction of a
miniball with the aid of an external electromagnet. The extraction
perforation is the same in diameter as the miniball extracted,
minimizing trauma. In an artery, extraction through the grid of an
impasse-jacket (qv.) is at a level proximate to the source so that
the perforation is small in relation to the diameter of the ductus
and usually remote from the level of eventaul embolization. In a
vein, greater separation between the source and the impasse-jacket
is used. Cf. stereotactic extraction.
[5283] Extraluminal approach--Approach to the wall of the ductus
from outside the adventitia; the approach used to inserts stays.
Approach thus calls for extraluminal in situ testing. Cf.
endoluminal approach.
[5284] Extraluminal stent--A stent that consists of
subadventitially implanted intraductal sperules referred to as
minitature balls or miniballs and a periductal (circumductal,
circumvascular, perivascular) magnet surround, or stent-jacket.
[5285] Extrinsically magnetized stent-jacket--An elastic polymeric
or copolymeric base-tube with bar-magnets mounted to its outer
surface, hence, discretely magnetized, or laminated (qv.) with an
intrinsically (qv.) or quasi-intrinscially (qv.) magnetized layer
bonded to its outer surface. An extrinsically magnetized
stent-jacket that includes a radiation shield is laminated, with
the magnets fastened to the shield layer which in turn, is bonded
to the outside of the base-tube. These are encapsulated together
for chemical isolation and cushioning before bonding the moisture
barrier-coated viscoelastic polyurethane foam lining. Cf.
intrinsically magnetized stent-jacket; quasi-intrinsically
magnetized stent-jacket; laminated stent-jacket; radiation shielded
stent-jacket.
[5286] Feed-forward use--The use of a service-catheter (qv.) to
deliver a temperature change or substance to the muzzle-head, to
the surface of the lumen, or to a point within the lumen wall.
[5287] Feed-back use--The use of a service-catheter (qv.) to
withdraw tissue, whether ablated, for biopsy, or both.
[5288] Fill-coat--A layer applied about a miniball (qv.) or stay
(qv.) to increase the ductus wall thickness after implantation. If
necessary, implantation-preparatory thickening of the wall is
accomplished through the use of a tumefacient. Following
implantation, the fill-coat may itself tumesce, or remain passive
and become absorbed. The fill-coat may consist of autologous tissue
and/or synthetic material to allow or promote infiltration by the
surrounding tissue. Otherwise, liposuctioned fat, for example, can
be injected through a service-catheter (qv.) with hypotube, or with
an injection tool-insert (qv.) before implantation.
[5289] Ferrobound--Said of a drug, radionuclide, and/or other
therapeutic substance which is chemically bound to a magnetically
susceptible carrier particle or nanoparticle and therefore drawn to
a magnet along with the susceptible component. The substance can be
infused, injected, or ingested as a ferrofluid without containment
within and apportionment among a number of miniballs or
microspheres, for example. When the ferrofluid approaches a holding
jacket (qv.), the carrier particles are drawn to the lumen wall
encircled by the holding jacket. Ferrobound agents are used to
treat lesions of the lumen wall, whereas ferro co-bound agents are
used to target tissue, lesions, or organs downstream. When
apportioned among miniballs or microspheres, dissolution of the
encapsulating layer or coat, which can be spontaneous or controlled
using heat or another chemical, has the same effect. Cf. ferro
co-bound.
[5290] Ferro co-bound--Said of a drug, radionuclide, and/or other
therapeutic substance which is accompanied by, that is,
mechanically but not chemically bound together with a magnetically
susceptible carrier particle or nanoparticle. When enclosed
together within a miniball or microsphere, or held within a
miniball or microsphere having an outer shell or coating that
contains magnetically susceptible matter, for example, the
thereapeutic substance remains with the susceptible matter until
the shell dissolves or is broken down by heating and/or the
introduction of a solvent or enzyme, for example. No longer bound
to the susceptible matter, the substance is freed to continue
moving through the ductus, such as in the bloodstream, gut, or
ureter. Cf. ferrobound.
[5291] Filter-deployment solenoid--A subminiature dc powered
plunger solenoid in the nose of the muzzle-head (qv.) located
behind the stowage silo of the trap-filter used to eject or deploy
and retrieve the trap-filter after use. It is dampened to prevent
abrupt jerks or jolts that could result in injury to the wall of
the lumen.
[5292] Fixed [radial projection] unit--A fluidically operated
radial projection unit with ejection-irrigation-aspiration function
inherent in its structure. Without a tool-insert holding and lift
platform and unable to accept tool-inserts, it is variable in the
rate and direction of flow-through passively as set at the external
control panel, but internally dumb, or invariable in function.
[5293] Flex-joint--A ring of elastic material interposed between
metal portions of the spindle (qv.) in the turrel motor rotor and
the splay chamber (qv.) to allow a predetermined amount of flexion;
flex-ring.
[5294] Flow-through ejector--A flow-through emission tool-insert or
emitter (qv.) for releasing a fluid into the lumen rather than
injecting it into the lumen wall. By distinction from an
electrical/fluid system-neutral or purely self-contained type
ejector. Lifting pressure (qv.) forces the lift-platform to rise
(move radially outward) uncovering the opening up into the
base-plug (qv.) inserted therein thus admitting fluid up into,
through, and out the working face of the tool-insert. A
flow-through ejection tool-insert can be prefilled as a syringe
with an initial load of medication to be ejected or injected ahead
of the line medication. Thereafter, different fluids can be drawn
from any number of reservoirs in any sequence each at a preferred
temperature with the line flushed as necessary ; flow-through
ejection tool-insert. Cf. in-line radial projection unit.
[5295] Flow-through emitter--A flow-through ejection tool-insert
(qv.) or ejector, or an injection tool-insert, or injector. By
distinction from an electrical/fluid system-neutral or purely
self-contained type emitter, which is limited to the type and
amount of fluid it contains but is therefore usable in an
electrical radial projection unit, a flow-through emitter delivers
fluid from a fluid line. Lifting pressure (qv.) forces the
lift-platform to rise (move radially outward) uncovering the
opening up into the base-plug (qv.) inserted therein thus admitting
fluid up into, through, and out the working face of the
tool-insert. The tool-insert can be prefilled as a syringe with an
initial load of medication to be ejected or injected ahead of the
line medication. Thereafter, whether an ejector or injector,
different therapeutic fluids can be drawn from any number of
reservoirs in any sequence, each at the preferred therapeutic
temperature. In an ablation or ablation and angioplasty-capable
barrel-assembly, reservoirs can be internal or external, the former
imposing space limitations that may require the use of reservoir
refill cartridges, the latter requiring lines that may reduce
manipulative freedom. Flow-through emitters and fluid lines may
require temperature insulation. Cf. injection tool-insert,
injector, ejection tool-insert, ejector, emitter, flow-through
ejector, flow-through injector.
[5296] Flow-through injector--A flow-through emitter (qv.) for
delivering a fluid through a hollow needle or multiple hypotubes
into the lumen wall. Lifting pressure (qv.) forces the
lift-platform to rise (move radially outward) uncovering the
opening up into the base-plug (qv.) inserted therein thus admitting
fluid up into, through, and out the working face of the
tool-insert. The internal chamber can be prefilled with a
medication other than that in the line, the initial load, which
thus injects ahead of the line medication. Thereafter, whether an
ejector or injector, switching among any number of reservoirs in
any sequence allows different therapeutic fluids to be injected,
each at the preferred therapeutic temperature. Flow-through
injectors thus avoid the limitations in quantity and temperature of
injectant that apply to syringe-type injection tool-inserts or
injectors. Cf. tool-insert, emitter, flow-through emitter, in-line
radial projection unit.
[5297] Flow-past resistance--The rise in antegrade blood pressure
due to obstruction by the muzzle-head (qv.) as a fluid
resistor.
[5298] Fluid system ejector--An emission tool-insert (qv.) or
emitter (qv.) for use in a fluid operated radial projection system
(qv.) to emit a fluid into the lumen. These can be either
completely self-contained electrical/fluid system-neutral syringes,
which in a fluid system, cannot heat the contents, or distinctly
fluidic flow-through (qv.) tool-inserts. A flow-through ejection
tool-insert can be prefilled as a syringe with an initial load of
medication to be ejected or injected ahead of the line medication.
Thereafter, different fluids can be drawn from any number of
reservoirs in any sequence, each at a preferred temperature. Larger
amounts of one or a number of fluids at the same or different
temperatures can be delivered through a flow-through ejector via
the fluid line, which can be flushed as necessary. Cf. ejector,
in-line radial projection unit, flow-through ejection tool-insert,
flow-through emitter, fluid system injector.
[5299] Fluid system injector--An emission tool-insert (qv.) for use
in a fluid (fluidic) radial projection unit to introduce an
injectant into the lumen wall. These can be either electrical/fluid
system-neutral syringes, which self-contained, are limited to
injecting a specific dose of medication or another substance while
remaining separate from the fluid or electrical circuit, or
distinctly fluidic flow-through (qv.) type tool-inserts. In a
flow-through (qv.) type injector (qv.), the base-plug (qv.)
connects the tool-insert to the fluid circuit but generally not to
an electrical circuit. Lifting pressure (qv.) forces the
lift-platform to rise (move radially outward) uncovering the
opening up into the base-plug (qv.) inserted therein thus admitting
fluid up into, through, and out the hypoendothelial or hypointimal
injection needle at the working face. Cf. emission tool-insert,
emitter, fluid system ejector, flow-through ejector, electrical
injector, electrical tool-insert, electrical emitter, fluid
tool-insert.
[5300] Fluid tool-insert--A tool-insert that must be connected to a
fluid circuit in order to be lifted or discharge fluid into the
lumen or lumen wall. By contrast with completely self-contained or
system unconnected electrical-fluidic system neutral tool-inserts,
which are used in fluid radial projection systems to emit a fluid
other than that in the line. A fluid emitter can also be prefilled
as a syringe with a fluid other than that in the line but does not
isolate the emittant (ejectant or injectant) from the fluid in the
line, which prevents fluids from mixing when undesired and allows
the fluid in the line to be used purely as an hydraulic medium not
necessarily requiring change with every procedure. Cf. fluid system
injector, flow-through emitter, in-line radial projection unit.
[5301] Foam-wedge--The inner or adluminal component of a
double-wedge insert lining (q.v.) for a shield-jacket (q.v.) or a
stent-jacket (q.v.) that serves to protect the adventitial
microstructures (vasa and nervi vasora) reduce the momentum of a
miniball, and trap any miniballs that perforate the adventitia. Cf.
bounce-wedge.
[5302] Forward drive and sag leveling and stabilizing device--An
extendable longitudinal scaffold or framework that holds the
barrel-catheter straight, as is essential to eliminate sag and
off-axis deflection when the airgun linear positioning table
advances the airgun to set the distance between successive
discharges; leveling and stabilizing linkage device, extracorporeal
barrel-catheter straightener and deflection preventing extension
linkage.
[5303] Full-round stent-jacket--A stent-jacket that except for a
side-slit (qv.) to allow it to expand in diameter, is completely
circular (cyclindrical) to allow encirclement of a ductus (a vessel
or a duct). It is made of resilient tubing to maintain clutching
contact with the outer surface of the ductus, and has a side-slit
that allows full compliance with the smooth muscle action in the
ductus wall; full stent-jacket, complete stent-jacket (as
contrasted with a partial stent-jacket (qv.).
[5304] Gas pressure relief channel--The portion of the gas pressure
relief path (qv.) that consists of a passageway machined into the
metal portion of the muzzle-head (qv.) spindle (qv.). In
multibarrel embodiments, each barrel channel is provided with a
feeder branch to the central channel in the muzzle-head (qv.) and
peribarrel space (qv.). The channel serves to divert the gas
pressure that builds up in the barrel-channel or channels (qv.)
during discharge, preventing the gas from entering the bloodstream;
gas return channel.
[5305] Gas pressure relief path--The passageway that diverts gas
pressurized during discharge from being expelled into the
bloodstream producing an air embolism. It takes the pressurized gas
through the gas pressure relief or gas return channel (qv.) and
then through the gas return tube continuous therewith and end-cap
(qv.) for return to the peribarrel space; gas return path; gas
return path.
[5306] Gas return tube end-cap--A least resistance path or set of
paths for relieving the expulsive pressure of the miniballs as
these exit the barrel-tube or tubes, thus averting the injection of
gas embolism into the bloodstream. Also to dissipate a buildup of
pressure, the barrel-tubes contain perforations along their
length.
[5307] Hand-grip--The addition of an ambidextrous pistol grip or
the imparting of an overall conformation to the power and control
housing of an ablation or an ablation and angioplasty-capable
barrel-assembly, a combination-form ablation or ablation and
angioplasty-capable barrel-assembly, a radial projection catheter,
or combination-form radial projection catheter to ambidextrously
fit the hand.
[5308] Heat-window--1. A thin silver or copper sheet area of high
heat conductivity in the surface of the muzzle-head (qv.) for
allowing heat to flow from the turret-motor (qv.) and/or recovery
electromagnet (qv.) windings when circuited to allow secondary use
for radiating heat when sent a surge-current. Used to apply heat
for any purpose, but primarily to achieve preemptive thermal
angioplasty of fatty atheromas and fibrous caps and contents to
prevent the release of debris from vulnerable plaques. For this
reason, the windows surround the muzzle-head, even though the
windings are separately heatable, adhesive backed
biaxially-oriented polyethylene terephthalate polyester film
(Mylar.RTM.) (thermal resistivity 1040) heat shield tape used to
reduce window area. 2. Another type of temperature changing window
consists of a tool-insert (qv.) blank (qv.). Whether the winding
cover or tool-insert type, electrical heat-windows can provide only
heat, whereas fluid operated `heat`-windows are temperature
changing tool-insert blanks that can provide both heat as hot
plates or cold as cold plates. Directional or radially asymmetrical
windows are slit or slot-shaped; thermal window;
temperature-changing window; thermal angioplasty window, thermal
window-slit, thermal window-slot.
[5309] [Tool-insert] Hold-down arms--Small levers used to retain a
tool-insert within the lift-shaft (qv.) against the force of
gravity and levering forces of contact with the lumen wall at the
tool-insert working face encountered in use. Hold-down arms are
positioned in depressions adjacent to the opening of the lift-shaft
at the surface of the muzzle-head (qv.) or radial projection
catheter (qv.). The levers rotate about or slide into complementary
round or linear depressions at the top of the tool-insert;
swing-over hold-down arms; hold-down clips, lock-down clips.
[5310] [Miniball or ferrofluid] Holding jacket--An impasse- or
stent-jacket for retaining, releasing, or heat-controlled releasing
of a therapeutic substance within a lumen, usually a blood vessel.
The substance can be formulated for delivery as a ferrofluid,
within microspheres, or a miniball with or without a magnetic
casing to remain bound to the carrier particle and thus drawn
abaxially against the lumen wall and into the intramural lesion or
to be separable from the carrier at the entry (inlet) or exit
(outlet) of the target organ. The particles include magnetically
susceptible matter which is bound to the therapeutic substance or
substances, so that the holding jacket draws the particles against
and into the targeted structure. The incorporation of magnetically
susceptible matter also allows the particles to be heated from
outside the body by an alternating magnetic field to accelerate
dissolution and/or uptake. Impasse- as opposed to stent-jackets
used as holding jackets have side walls of a fine wire mesh which
allows the use of an external electromagnet to extract minibals or
microspheres through the lumen wall to a point outside the lumen or
outside the body. A holding jacket can be used to remove or reduce
an endogenous, infused, injected, or ingested substance carried by
the bloodstream. Cf. margin-levering, [impasse-jacket] tie-downs,
[miniball] entry- [impasse- or stent-] jacket, [miniball] exit-
[impasse- or stent-] jacket.
[5311] [Clip] Hole-group--A group of holes positioned around a
rotary magazine clip for simultaneous discharge. The miniballs in
any or all groups can be the same or of different kinds, so that
ferromagnetic and medication miniballs, for example, can be
discharged together. Since each miniball is ejected through a
separate barrel-tube, the different type miniballs will be
implanted at different radial angles, so that to alternatively
implant the different types along the same longitudinal lines about
the circumference of the lumen or tracks necessitates rotating the
muzzle-head (qv.) with the turret-motor (qv.).
[5312] Idle flow--Flow of the line fluid in a fluid radial
projection unit circuit, or system, at too low a pressure to close
the least resistive check valve along the circuit and therefore
continues to flow through the circuit without actuating the most
pressure sensitive projection unit in the circuit. Cf. idle
pressure.
[5313] Idle pressure--In a fluidic radial projection unit (qv.)
circuit, a line pressure that is too low to close any of the fluid
chamber partition check valves so that fluid flows past these and
through the entire circuit. Pertaining to the radial projection
system or circuit as awhole, the idle pressure is established by
the valve that closes under less pressure than any other, although
normally, the units in a system are made to respond alike. The term
pertains to the line pressure whether antegrade or retrograde.
Increasing the line pressure over the idle pressure in the
antegrade direction precedes the lifting pressure (qv.) followed by
the emitting pressure (qv.), whereas doing so in the retrograde
direction leads to the lifting pressure followed by the intake or
aspirating pressure. Flow at idle pressure, or idle flow, allows
the direction of line fluid flow to be reversed without actuating
any units. The time to reach the unit actuating pressure in the
opposite direction is increased, but directional reversal at low
pressure substantially eliminates any tendency of the line to whip
or jerk that if extreme could cause stretching injury. Instead, the
response to an increase in pressure to the lifting pressure is
concentrated in the projection units reducing unit response time
and allowing sudden reversals that can be used to forestall
clogging, for example. Reversal in the direction of flow presumes
that tool-inserts in the circuit will not be actuated other than as
intended, so that, for example, an emitter which is not meant to
function as an aspirator is made to aspirate.
[5314] [Miniball or ferrofluid] impasse-jacket--A magnetic holding
or trap collar or mantle, prepositioned about a ductus, for drug
targeting a certain segment of a ductus or an organ or for
placement downstream from a magnetic stent-jacket encircling an
artery to prevent a miniball from passing. Impasse-jackets provide
an extraction grid (qv.) to allow noninvasive removal of the
suspended miniball in the lumen with the aid of an extracorporeal
electromagnet. For this reason, an impasse-jacket can incorporate
an outer radiation shield only when the shield is destructible on
demand by heat induction. The distinction between holding and trap
impasse-jackets is functional, not structural. A stent-jacket can
be used as a holding jacket but does not allow the noninvasive
extraction of a held or trapped miniball from outside the body. By
contrast, an impasse-jacket is configured to allow the use of an
external electromagnet to extract a held or seized miniball through
the lumen wall to a safe location. Its strength of magnetization,
focused at its center, must be sufficient to overcome the ability
of the pulse and gravity to force a miniball past it regardless of
patient posture. In the arterial tree, preserving proportionality
of size among lumen, miniball, and impasse-jacket allows trapping
the miniball while it is smaller in relation to the diameter of the
lumen. This minimizes the potential for embolization and
proportionally reduces the diameter of the extraction perforation
(qv.) or trajectory. The impasse-jacket is therefore placed as
close downstream to the prospective level of miniball release as
interference between the magnetic fields of the source and
impasse-jackets will allow. Proximity also allows incorporation of
a larger mass of magnetizable content to stop the miniball while
still distant from the level of embolization; impasse and
extraction jacket, trap-jacket, extraction jacket, stopping-collar,
guard. Cf. margin-levering, [impasse-jacket] tie-downs, [miniball]
entry- [impasse- or stent-] jacket, [miniball] exit- [impasse- or
stent-] jacket.
[5315] [Intramural] implant--A very small body inclusive of
sufficient magnetically susceptible matter to assure tractability
or recoverability, and usually including if not consisting
predominantly of medication. Extraordinarily, a surgical cement or
protein solder, rendered molten with the aid of a heating element
in the nose of the barrel-assembliy (qv.), for example, if not the
predominant constituent, is included. The implant is delivered into
the wall surrounding a tubular anatomical structure of any kind
(vas, vessel, ductus, gut, airway) by 1. Infixion through a small
incision at the body surface with the aid of a stay insertion tool
(qv.), 2. Aeroballistic discharge with the aid of a barrel-assembly
(qv.), 3. Injection with the aid of an injection tool-insert (qv.)
in either a radial projection catheter (qv.) or an ablation and
angioplasty-capable barrel-assembly (qv.), or 4. Magnetic
attraction from the lumen as ferrofluid-borne nano or
microparticles which once intramural. fuse together to form a
concrete mass. This multiplicity of options, which can be changed
at different levels along a ductus, allows the placement of
implants in even a deep and tortuous vessel, for example. Using the
last of these methods, introduction into the luminal flow of a
vein, for example, can be by conventional infusion or infusion
through a small body surface port (qv.) of ferrofluid-borne
magnetically susceptible-carried drug nanoparticles, or
microparticles. Incorporation into the lumen wall is with the aid
of a stent-jacket equipped with tiny electromagnets energized in
sequence where constitution of the intramural implants is by
aggregation from the passing blood, for example. Cf. periductal
implant.
[5316] Injection tool-insert--A radial projection unit tool-insert
(qv.) with at least one hypointimal, hypoendothelial, subintimal,
hypomucosal or submucosal injection needle. Spring-return of the
tool-insert (qv.) and recession by the lift-platform assure that
the tool working face needle or needles are fully retracted when
not in use. Self-contained syringe injectors that do not require
connection to a source of electrical or fluid power can be used in
either electrically or fluidically operated systems of given size.
Self-contained syringe injectors are, however, limited to the
amount and type of fluid these store within. When the bottom boss
or protrusion inserted into the mechanical retaining socket in the
tool-insert holding and lift-platform and the lift-platform also
establish electrical or fluidic connection, the contained fluid can
be warmed. Fluidic systems can also chill the contents. Injectors
can be insulated. Electrical connection can be used to power motive
means within the injector. Fluid system flow-through injectors can
be switched among multiple reservoirs containing different fluids,
to include flush water or carbon dioxide; injector. Cf. Radial
projection system, radial projection unit, in-line radial
projection unit, emitter, ejector, electrical ejector, fluid system
ejector, flow-through injector, flow-through ejector, injector,
injection tool-insert, electrical injector, electrical tool-insert,
fluid tool-insert, fluid system injector, syringe tool-insert,
syringe injector, syringe ejector.
[5317] In-line radial projection unit--A series-connected radial
projection unit (qv.) in an electrical or fluid circuit. While
jointly controlled as on or off and in electrical or fluid current,
exceptionally and strategically incorporating a different lifting
resistance into each tool-insert holding and lift-platform (qv.)
makes it possible for each unit to respond differently in timing
and force of elevation to the same current, and for fluid emitters
(qv.), in the force and volume of fluid ejection or injection. To
optimize functionality, all units, whether electrically or fluid
operated are capable of projection (elevation). When this
resistance is built into unremovable units so that it cannot be
changed, identical response from every unit cannot be obtained, so
that units of different resistance in a muzzle-head or separate
catheter are marked to indicate the resistance of each. When a
response that varies from the rest is not to be used, the unit can
be capped with a plug. Tool-inserts such as ejectors, electrical
heating, and fluid heating and chilling face-plates meant to remain
flush to the suface of the muzzle-head are separated from the
lifting mechanism by a gap. However, especially in an electrical
system, where fluid of opposite temperature cannot be quickly
introduced, retractability can assist to acceleratate removal of
the extreme temperature, even when retraction does not bring the
emitter closer to a temperature changing service-, or `cooling`
catheter. Cf. emitter,
[5318] [Stay] Insertion incision--the slit made through the tunica
fibrosa, tunica external, or adventitia by a stay as it enters the
wall of the ductus; term used to distinguish this incision from
that used to gain intracorporeal access, which is referred to as
the entry wound.
[5319] In situ test--A test to predetermine the exit velocity
(force of discharge) suitable for implanting miniballs into a given
segment of a ductus with minimal risk of perforation. Due to the
unpredictability of diseased tissue, in situ testing is
necessitated regardless of whether a stent-jacket is to be placed
prior to discharge. Implanting drug releasing and irradiating seed
miniballs does not call for a stent-jacket, which could be
justified only where a perforation could do serious harm.
[5320] Intake pressure--In a fluid radial projection system, the
line pressure in the retrograde direction at which a given
tool-insert is forced to aspirate. The intake pressure follows
first the idle pressure (qv.) then the lifting pressure (qv.) and
is the reciprocal of the emitting pressure (qv.); aspirating
pressure.
[5321] Interventional airgun--A special-purpose gas-operated
implement for implanting ferromagnetic, medicated, or gamma
radiation emitting seed spherules into tissue by projection. Proper
adjustment in the force of impact critical and capable of changing
from point to point along the tissue, in situ tissue testing and
the ability to reset the airgun quickly and precisely
midprocedurally can be critical, prompting the development of
special-purpose airguns having multiple control points for quick
resetting.
[5322] Intrinsically magnetized stent-jacket--A homogeneous single
layer, such as one consisting of thin sheet stock magnetized
stainless steel or a magnetic polymer or copolymer, that provides
the magnetization and structural properties required in a
stent-jacket (qv.). An intrinsically magnetized layer bonded to the
base-tube of an extrinsically (qv.) or intrinsically magnetized
stent-jacket to increase its magnetic force or resilience and not
usable independently as a stent-jacket is a layer in a laminated
stent-jacket, not a stent-jacket. Radiation shielding materials
such as tungsten paramagnetic and thus unable to provide the
magnetization needed in a stent-jacket that except for the moisture
barrier-coated viscoelastic polyurethane foam lining consists of a
single layer, the addition of radiation shielding is by lamination.
Cf. extrinsically magnetized stent-jacket; quasi-intrinsically
magnetized stent-jacket; laminated stent-jacket; radiation shielded
stent-jacket.
[5323] Jacket--The component device used to collar about or
encircle a ductus whether vascular, endocrine, gastrointestinal, or
pulmonary; stent-jacket.
[5324] Joint [barrel-assembly or projection catheter]--A divisible
ablation or ablation and angioplasty-capable barrel-assembly or a
radial projection catheter consisting of two components where the
more peripheral or outer is slid over and ensheaths the more
central or inner, the two then used as one. For use in larger
lumina, the use of a third or fourth ensheating projection catheter
is possible. By definition, an outer or ensheathing component is a
combination-form (qv.), while the inner may be either simple (qv.)
or itself a combination-form. The outer or outermost component can
be exchanged (switched, `swapped`) among any number of others
differently equipped as to radial projection circuits (qv.),
tool-inserts(qv.), and preloaded medication, for example.
Midprocedural ensheathment can be purely to increase the outer
diameter, and removal or disensheathment of the outer or outermost
to reduce stiffness, but more often uses ensheathment to deliver a
capability or therapeutic substance not preloaded in the more
inward or central component. When there is one outer component, the
joint device is bipartite, when three, tripartite, and so on. Cf.
combination-form radial projection catheter.
[5325] Jointed stent-jacket--A stent-jacket that consists of
separate segments of tubing articulated to allow flexion as to
preclude any buckling in the side-slits (qv.); articulated
stent-jacket.
[5326] Laminated stent-jacket--Any stent-jacket that except for a
universally required moisture barrier-coated viscoelastic
polyurethane foam lining, consists of more than a single layer.
This excludes extrinsically magnetized base-tubes, intrinsically,
quasi-intrinsically magnetized, and radiation shielded
stent-jackets. Radiation shielding materials such as tungsten
paramagnetic and thus unable to provide the magnetization needed in
a stent-jacket that except for the foam lining consists of a single
layer, the addition of radiation shielding is by lamination. The
laminated layers are usually encapsulated for chemical isolation
from the internal environment and to provide cushioning. Cf.
extrinsically magnetized stent-jacket; intrinsically magnetized
stent-jacket; quasi-intrinsically magnetized stent-jacket;
radiation shielded stent-jacket.
[5327] Lifting height--The distance the tool-insert (qv.) is
lifted. Lifting height varies independently of tool-insert height;
radial distance, excursion, radial throw.
[5328] Lifting pressure--In a fluid radial projection system or
circuit, that pressure sufficient to raise a tool-insert into
working position. While each unit could be made to rise at a
different pressure, differential operation among units in a circuit
is generally relegated to the individual tool-inserts, so that this
factor usually pertains to the radial projection system or circuit
as a whole. Varying the resistance of the chamber partition check
valve and/or the lift-platform strip-spring would cause each unit
to rise in a preferred sequence; however, the units in a system are
usually made uniform. A lifting pressure is equal to the idle
pressure plus any additional pressure necessary to overcome the
resistance posed by the lift-platform strip-spring, and is thus
intermediate between the idle pressure (qv.), and, during antegrade
flow, the emitting pressure (qv.), during retrograde flow, the
effective intake pressure (qv.).
[5329] [Radial projection unit tool-insert holding and]
Lift-platform. The tool-insert (qv.) raising, and lowering deck at
the bottom of the lift-shaft (qv.) in a radial projeciton unit
(qv.). When the tool-insert is friction fit into a receptacle in
the lift-platform or deck, the part is a tool-insert holding as
well as lift-platform. The lift-platform raises the tool-insert
into working position and retains it within the lift-shaft when not
in use. When also used to retain the tool-insert by friction fit as
a tool-insert holding and lift-platform, the lift-platform has
rising walls about to provide a socket. The lift-platform may
incorporate internal elements such as a socket to receive a
tool-insert base-plug (qv.), which in an electrically operated unit
provides the electrical and in a fluid unit the fluid connection to
the circuit. The socket can also also serve to friction fit
tool-inserts when swing-over hold-down arms (qv.) are not provided
at the surface of the muzzle-head (qv.) or separate (special)
radial projection catheter (qv.). The lift-platform is raised by a
thermal expansion wire or the elecrically actuated release of a gas
in electrical units and by fluid pressure in fluid units.
Retraction in both type units is by a strip-sping (qv.) beneath the
platform of which the force must be overcome by the lifting
mechanism.
[5330] [Radial projection unit] Lift-shaft--A small elevator shaft
or well in which a small elevator or lift-platform with a
receptacle for inserting any of a number of interhangeable
tool-inserts (qv.) rides up and down to either extend the working
face of the tool radially outwards or retract it within.
[5331] Limited purpose barrel-assembly--A radial discharge
barrel-assembly (qv.) which lacks components essential to perform
an ablation or an angioplasty.
[5332] Magnetic stent-jacket--A resilient tube or base-tube with a
slit cut along its side, small bar magnets mounted about its outer
surface, and intramural ferromagnetic implants for retracting an
implantable ductus wall, such as that bounding an artery. Depending
upon the application, may incorporate side-straps or belt-straps to
assist in preventing migration.
[5333] Magnetless stent-jacket--A resilient tube or base-tube
without magnets or intramural ferromagnetic implants for the
circumvascular restraint of an unimplantable ductus wall such as
that bounding an aneurysm or similar bulging or outpocketing of a
ductus. Lacking magnetic attractive support, the intrinsic
resilience of the base-tube, belt-type straps or belt-straps, and
belt-strap tightness used to secure the base-tube about the defect
become significant. The stretchability of the straps essentially
substitutes for a portion of the adherence that in a magnetic
stent-jacket is provided by magnetic attraction.
[5334] Magnet-trap--The miniball trap-chamber or antechamber of a
recovery electromagnet, or trap-magnet, used to enclose and retain
recovered miniballs. Distinguished from a filter trap (trap-filter,
embolic filter). Cf. trap-extraction magnet assembly,
trap-filter.
[5335] Magnet-wrap--A wrap-surround (qv.), or bandage, in the form
of a stretchable collar or cuff for encircling a ductus,
ordinarily, one neighboring another ductus or other tissue
requiring retraction whether due to stenosis, collapse, or
encroachment by or on neighboring tissue. The magnet-wrap mounts
permanent magnets for attracting ferromagnetic implants in or
attachments to the failed ductus, for example. On a neighboring
ductus such as the esophagus relative to the trachea, the wrap
situates the permanent magnet or magnets parallel to the
ferromagnetic implanted area in the trachea to lift the dorsal
membrane or ligament. Only the facing arcs of the ductus or other
tissue carry the attractable implants or magnets. Use in a small
dog of the esophagus as a platform to support a collapsed trachea
where these are juxtaposed is but one application;
magnet-wrap-surround, magnet-cuff, magnet-bandage, magnet-jacket,
magnetic collar.
[5336] [Impasse-jacket] Margin levering--Sudden downward thrust at
one end of an impasse-jacket (qv.) under the repulsive force of an
extraction electromagnet (qv.). If not suppressed, margin levering,
just as ductus-transverse displacement (qv.), can result in sudden
wrenching, or flexion and stretching injury to the substrate
(encircled) artery. When extension in length to present a greater
moment of resistance to lopsided displacement at either side by one
continuous impasse-jacket is disallowed by segments along the
ductus that are diseased, curved, tortuous, have attachment to
neighboring tissue wished preserved, or span a level that must be
free to flex, the length is effectively extended by spanning over
these segments. Such spanning for elongation is achieved through
the use of an interrupted or braced stopping-jacket (qv.), wherein
only the impasse-jacket itself at the center is magnetized. If
necessary, the impasse-jacket and outriggers (qv.) can be sutured
down to subjacent tissue thereby reducing any space or tenuous
connective tissue overlying hard tissue; levering; edge-thrusting,
edge-pushing, margin-pushing. Cf chain-guard, braced
impasse-jacket, [impasse-jacket] tie-downs, ductus-transverse
displacement.
[5337] Medicated miniball--A spherule for implantation, usually
within the wall of a vessel, that incorporates medication which may
surround a spherical seed type source of particulate or gamma
radiation as a medicated seed miniball (qv.).
[5338] Medicated stay--A stay (qv.) for implantation within the
wall of a vessel that incorporates medication normally as the outer
coating thereof but which may surround a spherical seed type source
of gamma radiation as a medicated seed stay; tablet stay. Cf.
medication stay, medicated miniball, medication miniball.
[5339] Medication-ahead operation--The use of a stay insertion tool
(qv.) auxiliary syringe (qv.) to discharge semiliquid medication
onto the outer surface of a ductus so that the stay in passing
through carries a coating of the medication on both its upper and
lower surfaces into the ductus wall; medication-before operation.
Cements and therapeutic substances that are too light or low in
viscosity (`thin,` `runny`) may require thickening. Cf.
cement-ahead operation.
[5340] Medication-follower operation--The use of a stay insertion
tool (qv.)auxiliary syringe (qv.) to discharge semiliquid
medication onto a portion of the upper surface of each stay as it
exits. The longitudinal extent of the coating is controlled by
adjusting the timing of auxiliary syringe motor actuation, and
while adjustable from stay to stay, is normally kept uniform from
one stay to the next; medication-after operation. Cements and
therapeutic substances that are too light or low in viscosity
(`thin,` `runny`) may require thickening. Cf. cement-follower
operation.
[5341] Medication miniball--A miniball that consists solely of
medication; pill-miniball. Cf. medicated miniball.
[5342] Medication stay--A stay (qv.) that consists solely of
medication and is fully absorbed. Cf. medicated stay.
[5343] Melt-barrier--A partition, usually made of wax, used to
divide and thus create separate chambers in an electrochemical
tool-insert (qv.) so that each chamber can be filled with a reagent
that when mixed with the other reacts to produce heat and/or
release a gas. The barrier extends up through a slot-shaped opening
running along the top of the roof, so that when the wax barrier is
melted, the slot serves as an outlet for the gas generated. To mix
the reagents, the barrier is melted by passing current through a
heating wire, such as one made of nichrome, embedded in the
partition and running through the plug in the base of the
tool-insert to plug into the socket at the bottom of the lift-shaft
(qv.). When used to lift a separate syringe tool-insert (qv.) into
the injection position, the syringe sits atop this double
compartment; when the working face of the tool-insert itself is to
lift into position against the lumen wall to apply heat under
pressure, a gas-tight cap overlapping the roof of the lower
chambered portion of the tool-insert is elevated by the gas. Such a
tool-insert essentially includes its own lift-platform.
[5344] Miniball [Miniature ball]--A spherule projectile such as
that used in `BB` guns but much smaller, for use in man, for
example, generally ranging in diameter from 0.25 to 2.0
millimeters, and most often 1.14 to 1.52 millimeters. Manufactured
in large volume, miniballs are used in bearings, ballscrews, and
ballpoint pens, and can be ferromagnetic or magnetic. consist
entirely of medication, represent small spherical irradiating
seeds, or within the caliber usable, combine these in concentric
layers; spherule, miniature sphere, minisphere; spherule,
minisphere.
[5345] Miniball-hole--The opening in a rotary magazine clip in
which a miniball is fixed in position for discharge. The distal and
proximal holes describe the openings to a tunnel that runs through
the clip, and an internal circumferential ridge midway along the
tunnel prevents the miniball from dropping into the barrel. Various
dried solutions of sugars and starches that differ in retentive
strength are used for added adhesion until discharge or to
differentially adjust the relative propulsive force essential to
initiate the ejection, hence, the muzzle velocity, of a given
miniball in a set of miniballs for simultaneous discharge as a
set.
[5346] Miniball-magnet--A magnetized miniball, which can
additionally be coated for the delivery of medication or
radiation.
[5347] Minimally ablation or ablation and angioplasty-capable
barrel-assembly--An airgun barrel-extending catheter, or
barrel-assembly (qv.), devised to allow intermittent or continuous
ablative or angioplastic treatment during discharge implantation;
minimally airgun-independent capable barrel-assembly.
[5348] Mixed [chain-stent]--An articulated rather than a segmented
unitary chain-stent wherein the sub-stents (qv.) differ to meet the
different requirements of the segment encircled by each. Thus,
consecutive sub-stents may incorporate magnetized metallic
base-tubes or magnet-mounting polymeric or nonmagnetic metallic
base-tubes, for example. Cf. articulated and segmented
[chain-stents].
[5349] Mixed shot-group--A shot-group (qv.) containing more than
one kind of miniball (qv.), such as one ferromagnetic for use with
a magnetic stent-jacket (qv.) and one that consists of medication.
Either consistent assignment of given type miniballs to a specific
barrel-tube or use of the turret-motor (qv.) is used to include the
different types along different tracks (qv.).
[5350] Monobarrel [barrel-assembly]--A barrel-assembly having one
barrel-tube. A monobarrel can be of the simple pipe kind and thus
end-discharging through a singular muzzle-port at the distal end or
housed within a more or less shuttlecock or torpedo-shaped
muzzle-head with the muzzle-port or ports about the circumference
referred to as a radial discharge monobarrel type barrel-assembly.
Whereas a simple pipe is for use in the airway, a radial discharge
barrel-assembly is for use in ductus and embodiments for use in
blood vessels must incorporate features to prevent the backflow of
blood into the muzzle-head or the injection of gas into the
bloodstream during discharge. Such features include pressure relief
means in the form of a barrel-catheter (qv.) to provide a
peribarrel space (qv.) within, and an extracorporeal one-way safety
valve at the proximal end of the barrel-catheter, and gas return
channels (qv.) in the spindle (qv.) to bleed off excessive gas
pressures before these can arrive at the muzzle-port.
[5351] Motorized swivel joint--A remotely rotated junction in a
radial discharge monobarrel (qv.). With only the one barrel-tube,
rotation is concentric with no rotatory deflection.
[5352] Motorized turret joint--A remotely rotated junction in a
radial discharge multibarrel (qv.). Since plural barrels must be
off-center, rotation imparts a rotatory deformation and
longitudinal foreshortening to the barrel-tubes, which must be
compensated by pliancy, slack in the splay chamber (qv.), and
reciprocal movement in the barrel-tube-(qv.) barrel-channel (qv.)
joints.
[5353] Multibarrel [barrel-assembly]--A barrel-assembly with
multiple (plural) barrel-tubes, which is always of the
radial-discharge type; multiple barrel barrel-assembly.
[5354] Multistage magnetic drug-targeting--Encirclement with
magnetic collars (jackets, mantles, wrap-surrounds) which are
compliant with the intrinsic smooth muscle action of the ductus or
the positioning of magnetized miniballs or stays at successive
points along the path of a bodily substance or a gland or organ
associated with the substance for the purpose of accelerating the
uptake of a drug or other therapeutic agent by the target
substance, gland, or organ. Mantling thus comprehends primarily
impasse-jackets, but also stent-jackets and magnet-wraps, and
mantiling at the successive can use that type jacket best suited to
the anatomy. Patch-magnets are suited to such use only when
resistance to contraction of the ductus is permissible. For
example, a first impasse-jacket at a level of the gut shown by
magnetic marker monitoring to best absorb the drug would serve to
draw the magnetized nanoparticle-bound drug against the villi for
quicker passage into the bloodstream, for example, while a second
impasse-jacket mantling about the main artery leading to the
targeted gland, organ, lesion, or neoplasm would draw the drug into
that lesion, for example. Cf. single stage magnetic
drug-targeting.
[5355] Muzzle--The distal terminus of the airgun, not to be
confused with that of the muzzle-port(s) or extended muzzle(s).
[5356] Muzzle barrel--The portion of a barrel distal to the
insertion and end of the plastic barrel-tube into its muzzle-head
flush joint socket and start of the metal portion of the
barrel.
[5357] Muzzle-head--The component mounted at the front or distal
end of the barrel-assembly barrel-catheter (qv.) containing the
barrel exit port or ports and the trap-extraction magnet assembly;
muzzle-probe. A distinct muzzle-head is characteristic of radial
discharge barrel-assemblies; however, the term applies to simple
pipe barrel-assemblies as well, in which distinction as the
muzzle-head consists of no more than a rotary joint in the
barrel-catheter.
[5358] Muzzle-head access barrel--A barrel-tube used, for example,
to allow a lubricant or medication to be delivered to the
endothelium through a muzzle-port or a cooling catheter to be
aligned in closer adjacency to a heated element; service-channel,
barrel-assembly distal access barrel-tube.
[5359] Muzzle-port--A miniball exit-hole at the distal terminus of
a simple pipe muzzle-head or short of the tractive electromagnet
set in a radial discharge barrel-assembly barrel-tube; ejection
port.
[5360] [Muzzled-] spindle--The rotating part of the muzzle-head
distal to the turret-motor housing; muzzle-head spindle.
[5361] Muzzle velocity--The velocity upon exiting the muzzle-head
exit portal, or muzzle-port. Since the term would conventionally
apply to the velocity of the projectile as it exits the muzzle of
the airgun rather than the muzzle-port at the distal end of the
barrel-assembly, the term exit velocity is preferred.
[5362] Needle-switch--A normally open single pole double throw
miniature lever switch on an electrical syringe injector (qv.),
which is closed by the force of obstruction against the
needle-flange.
[5363] Nose--The front end, or more restrictedly, the face-on
aspect of the front end, of a barrel-assembly (qv.) or radial
projection catheter(qv.). Except in thermal angioplasty or
ablation-incapable and combination-form (edge-discharge,
through-bore) barrel-assemblies (qv.) and radial projection
catheters, it is usually occupied by a heat-window (qv.) for
minimizing the risk of disrupting vulnerable plaque on contact. A
fiberoptic endoscope may be centered in the heat-window. Cf.
nosing, nose-cap.
[5364] Nosing--The treatment at the nose of a barrel-assembly (qv.)
or radial projection catheter(qv.). A combination-form will have an
opening, or nose-hole (qv.), that depending upon the application,
may remain open, such as to allow blood to pass through, or is
occupied by a laser, atherectomy, or other commercial cabled
device. A rotatory or directional atherectomizer is kept receded
behind the nose-hole, which remains open and is urged against the
lumen wall when a spring at a distance behind the nose emerges. The
nose of a simple (noncombination-form, boreless) radial projection
catheter will usually have a fine fiberoptic endoscope centered
within a heat-window (qv.). In larger embodiments for use in the
gastrointestinal tract or trachea and bronchi way where debris must
be prevented from entering when the bore is vacant, a push-through
annular brush or a snap-in spring-loaded nose-hole plug, or
nose-cap, is used to seal the nose. The nose-hole will usually by
encircled by a heat-window for searing vulnerable plaque and any
potentially embolizing debris liberated. For an improved field,
cabled devices for viewing and lasering usually protrude somewhat
forward of the nose center. Cf. Nose.
[5365] Nose-cap--A plug for sealing the opening at the front end of
the central channel (bore) or nose-hole (qv.) in a combination-form
(qv.) radial projection catheter (qv.) or in the edge-discharge
(qv.) muzzle-head of a combination-form (through-bore,
edge-discharge) barrel-assembly. Snapping in with prongs that
undercut a slight rim surrounding the nose-hole, and having a
spring-loaded hinged cap that automatically closes when not forced
open, it is removable to allow the central channel to be passable
only when outside the body. While competitive in cost, it is not
preferred either for preventing the entry of debris into the
central channel in the gastrointestinal tract, for example, where a
push-through surround of wiping fingers cleans the retracting
distal end of the device uniformly all about and closes off the
nose-hole behind the retracted device as preferred, nor for urging
a centered side-cutting device such as a rotational burr or linear
shaver, for example, into approximately parallel abutting relation
with the lumen wall in an artery or with any similar ablation
device in the airway, for example.
[5366] Nose-hole--The opening at the distal (front) end or nose of
the muzzle-head in a combination-form (through-bore,
edge-discharge) barrel-assembly or acombination-form (through-bore)
radial projection catheter. Cf. nose-cap.
[5367] One-over barrel-assembly--A barrel-assembly (qv.) with at
least one barrel-tube more than is needed for implantation. The
additional barrel-tube serves as a service-channel, that is, allows
adjunct function or service catheters, such as a test rod (qv.) or
cooling capillary catheter (qv.) to be passed down to the
muzzle-head. For cooling, this is significant with edge-discharge
(combination-form, through-bore) barrel-assemblies, which lack a
central canal.
[5368] [Impasse-jacket] Outrigger--A shorter collar end-braced to
an impasse-jacket (qv.). An upstream or entry outrigger is
unmagnetized, and when used only to minimize levering of the
impasse-jacket, the exit-outrigger or exit-collar is unmagnetized
as well. If to prevent any drug that was not taken up by the
impasse-jacket from passing downstream, the exit-collar is
magnetized, it is not a dummy-collar, which is an unmagnetized
outrigger.
[5369] [End-tie] Outriggers--The binding straps connected to the
ends of the suture tie-lines of end-ties (qv.) used to bind the
lines to the ductus off to either end of the jacket. Whether
unilateral or bilateral, the straps attach with hooks and loops.
These and any other straps applied directly to a ductus have a
backing of a highly elastic and porous or `breathing` fabric such
as spandex, and to protect the adventitia, an internal lining of
expansion-jointed moisture barrier-coated viscoelastic polyurethane
foam. If the stretching open of the joints between the foam
segments is too brief for `breathing` or ion exchange, then the
strap is perforated. End-tie end-tab type outriggers are
end-anchors tethered by suture that serve to resist migration and
can do so about a point of flexion, for example, whereas
impasse-jacket type outriggers are metal bridged, or hard-braced,
end-anchors that serve primarily to resist levering of the
impasse-jacket in an extraction and secondarily its migration. To
afford ribbing for improved traction or grip when the closed strap
is especially susceptible to sliding, the internal or binding
surface is overlain with wide mesh gauze; end-collar, end-cuff,
end-tab.
[5370] [Impasse-jacket] Outriggers--Nonmagnetized or dummy-collars
connected by rigid bridge-arms to the ends of a center
impasse-jacket. The outriggers are constructed as is the
impasse-jacket of two mesh half-tubes connected by spring-hinges
with moisture barrier-coated viscoelastic polyurethane foam
cuff-linings but are usually shorter than the impasse-jacket and
not magnetized. This produces a longer structure that is less
susceptible to impasse-jacket margin levering (qv.), and
interrupted or noncontinuous, allows segments of the ductus to be
rigidly spanned across (straddled, skipped over) when diseased, the
attachment thereto is to be preserved, the segments are tortuous,
or must be free to flex. When necessary, the outrigger end-cuffs
(qv.), as those of the impasse-jacket itself, can be tied down with
suture to the closest neighboring tissue of sufficient strength to
disallow ductus-transverse displacement (qv.); however, this will
usually require lengthening the access incision; dummy-collars. Cf.
[impasse-jacket] ductus-transverse displacement, levering,
chain-guard, rim-bridge.
[5371] Paired jacket release and neutralization--The use one
impasse- or other type jacket to trap drug carrier bound
magnetically susceptible nanoparticles, usually from the blood, and
into the wall of the ductus encircled by the jacket. When the drug
is not bound directly to as ferrobound but rather ferro-cobound,
upon dissolution of the common encapsulating layer, the carrier is
drawn against or into the lumen wall and the drug freed to continue
upstream. A second exit jacket then performs the corresponding
process to neutralize the action of the drug limiting its action to
the segment or organ separating the exit from the entry jacket. Cf.
Single jacket release, single stage magnetic drug-targeting, paired
jacket release and neutralization.
[5372] Partial stent-jacket--A stent-jacket with a longitudinal
band or slot of the base-tube removed to expand the slide-slit into
a side-slot needed to clear an obstruction such as a running
attachment of connective tissue. A cutout to admit a branch or an
expansion insert (qv.) can be applied to any base-tube, whether
full-round or partial; slotted stent-jacket. Used in
contradistinction to a complete or full-round stent-jacket
(qv.).
[5373] Passive delivery [to an impasse-jacket, outrigger, or other
type jacket]--Introduction of a drug carrier into an impasse-jacket
(qv.), outrigger (qv.), or other type jacket through the enteral
path, or by normal flow through the ductus rather than by injection
or infusion. Both active and passive delivery apply no less to
nonmagnetized jackets. Cf. active delivery.
[5374] Patch-magnets--A usually disk shaped more powerful neodymium
iron boron permanent magnet that is magnetized in its diametrically
central axis and encapsulated within a bioinert jacket mounted on a
base with prongs or clasps for attachment to the tissue surrounding
a ductus, an organ or deep (muscle) fascia. Patch-magnets are used
where stronger magnetic field strength is needed to draw wide stays
implanted at a distance or drug carrier particles passing at that
level into the ductus wall or organ. In gastrointestinal and
tracheobronchial applications, placement is by clasp or prong
undercut attachment into the outer layer or layers of the substrate
structure or organ, subcutaneous, or to connective tissue such as
deep or muscle fascia overlying implanted wide stays, miniballs, or
clasp-wrap (qv.) to be attracted. Patch-magnets like segmented
stent-jackets can be provided in a continuous strip from which any
number can be removed for use; clasp-magnets, magnet-clasps.
[5375] Perforation--The through-and-through penetration or puncture
of the lumen wall as the result of excessive exit velocity
(momentum) or impact force.
[5376] Peribarrel[-tube] space--The space surrounding the
barrel-tubes in the barrel-catheter. Made accessible to the gas
that is pressurized during discharge of the airgun through
perforations in portions of the barrel-tubes and centering devices
inside the patient, this space allows the pressure to be
transmitted from the front to the sides and back of the advancing
miniball and thus equalized within the barrel-catheter without the
release of gas into the bloodstream.
[5377] [Periductal] implant--An absorbable or nonabsorbable
stent-jacket (qv.) or impasse-jacket (qv.) Cf intramural implant.
When placement is not in a field opened for other surgical
purposes, periductal implants are placed endoscopically with the
aid of insertion tools described herein through a small incision at
the body surface. Access to the coronary vessels is by trephining
through the scapula.
[5378] Peripheral component--In a barrel-assembly (qv.), the radial
projection system circuit or circuits about the periphery of the
muzzle-head and all but the exit port or ports of the ballistic
component (qv.). In a barrel-assembly of large gauge such as for
use in the trachea, bronchi, or gastrointestinal tract, the
peripheral component can extend over the intracorporeal length. In
a through-bore or combination-form radial projection catheter
(qv.), the radial projection system circuit or circuits about the
central (cable) component (qv.). The peripheral component includes
either or both electrical and fluidic radial projection system
circuits.
[5379] Piped [radial projection] unit--A radial projection unit
(qv.) with supply line (supply tube, passageway, lumen, channel,
conduit) which allows perforated ejection or injection tool-inserts
(qv.) to release into the lumen, inject into the lumen wall, or
aspirate fluids. The fluid can be a drug, hot or cold gas, or drug
delivered at a certain temperature, for example. Piped radial
projection units have a wider range of function than electrically
operated nonpiped units, which are able to lift cutting and heating
tool-inserts, for example, into working position, but can deliver
only so much fluid as the syringe can hold. Fluid operated units
can eject or inject as well as use the line fluid to raise the
lift-platform (qv.); fluid operated [radial projection] unit.
[5380] Plunger-piston--The multiflanged elastomeric cap-plug at the
top of the adhesive cartridge that is inserted into the chamber
above the stay load queue. It is forced deeper into the barrel of
the cartridge to expel a constant aliquot of adhesive by air pump
action; piston-plunger, air pump piston-plunger.
[5381] Point to point diagnosis and therapy--The use of a
multibarrel radial discharge (qv.) barrel-assembly (qv.) as a
diagnostic and/or therapeutic tool whereby its barrel-tubes (qv.)
are used as service-channels (qv.) to pass diagnostic sensing
probes and therapeutic catheters down to the exit-holes. Such a
catheter is typically equipped with a distal or front-end hypotube
injection needle, for example. Other catheteric therapeutic devices
chill, heat, burn, cut, apply an electrical current, and so on. The
turret-motor (qv.) is used to rotate the muzzle-head at that level
(longitudinal position, translational displacement) along the lumen
so that the therapeutic exit-hole (qv.) is brought to the same
point where the diagnostic finding was obtained, and used to
deliver the therapeutic substance the finding indicated. The same
or another diagnostic probe can then be rotated to face the same
point to confirm that the effect intended was obtained, and so on.
This process is critically accelerated under the automated control
of a positional control system, which controls the linear stage as
translation mover, the turret-motor as rotational angle driver; and
coordinates the retraction, projection, and ejection of the
hypotubes or the functions of other type analytic and therapeutic
devices as auxiliary functions. Machine control allows each probe
and catheter to be returned to the exact same spot. When used for
implantation as well as to diagnose and treat, the muzzle-head
alternately rotates a diagnostic probe to the point, if the finding
or findings indicate the necessity therefor, the
findings-responsive followup therapeutic probe or probes indicated
to the same point, a post-treatment confirmatory diagnostic probe
if appropriate to that point, and when used for implantation as
well as diagnosis, the exit-hole (qv.) for ballistic discharge to
that point. When laying down a tighter formation of miniballs, such
as to evenly distribute the retractive force of a stent-jacket, the
use of automatic means for controlling the process is necessary
both for time and precision. Combining syndrome-dedicated and
critical path software allows response to the diagnostics such that
several different points are tested and treated concurrently;
imparting a level of coordination and efficiency that minimizes
procedural time and eschews the human error that more complicated
sequencing would likely educe; point-to-point diagnosis [or
diagnostics], point-to-point diagnosis [or diagnostics] and
therapeutics.
[5382] Point-washer--A fluid circuit line antegrade-retrograde flow
bidirectional tool-insert consisting of an irrigator and an
aspirator unified in back to back relation. Reversing the line flow
reverses which subunit of the tool-insert is the emitter and which
the aspirator. Water or any sufficiently fluid therapeutic solution
can be passed through the line. Point-washers can follow ejectors
or injectors to quickly remove excess emittant, for example;
doublet, back-back tool-insert, back-to-back doublet
tool-insert.
[5383] [Body surface] port--A small body with openings positioned
cutaneously, subcutaneously (subdermally), or both to allow the
introduction of medication or other medicinal agents or the
withdrawal of diagnostic biopsy test samples in patients with a
serious chronic condition, especially when the patient is incapable
or drug regimen compliance, necessitating automatic administration.
Outflow to the exterior such as to pass urine to a collection bag
requires an external opening, while openings for incurrent delivery
by infusion are subdermal and marked on the skin with a tiny
tattoo.
[5384] Power and control housing (and hand-grip)--An enclosure that
slides along the barrel-catheter of an ablation or ablation and
angioplasty-capable barrel-assembly (qv.). It contains a battery or
batteries and control circuitry that allow use of the
barrel-assembly as an independent apparaus for performing an
ablation or an angioplasty or to inject medication, for example,
into the lumen wall. Airgun-independent incapable and capable
barrel-assemblies of like diameter can use the same removable
slidable power and control housing, and insert adapters can allow
the same power and control housing to be shared among
barrel-assemblies of different diameter. Any electrical lines for
connection to the barrel-assembly plug into a set or bank of jacks
or receptacles, a side-socket (qv.), mounted to the housing. Cabled
and fluid equipment are connected with a passageway into the
barrel-assembly central canal (qv.) through a separate housing
about the barrel-catheter that is fixed in position, or if
incorporated into the slidable housing, limit the housing to the
connection point until disconnected. The components of inmate
fluidic systems, to include refillable reservoirs and pumps, are
permanently connected, either through lines that afford the
necessary slack or as contained within a separate housing fixed in
position proximal to the slidable housing. The components within
the separate fluid supply housing can, however, be controlled
electrically from the slidable housing.
[5385] Probe-rod--A fine rod for passing down a barrel-tube so that
the lumen wall can be prodded to test its penetrability or
deliberately punctured to a limited depth in order to ascertain the
susceptibility for the layers of the ductus or tunics to
delaminate. A measuring instrument may be used at the driven end to
quantify these results.
[5386] Proximal--Closer to the operator than the point of
reference.
[5387] Pull-through--The outward or centrifugal extraction of
miniballs or stays through the superjacent layers of the lumen wall
that separate these from the internal surface of the stent-jacket
under the sustained pull of the circumsurfacial magnets of the
stent-jacket over time or under the sudden intense force of a
vasospasm. The use of broad cyanoacrylate-coated stays minimizes
the risk of pull-through, which can result from sustained
nonuniform or disproportionate distribution of magnetic traction on
one or a few miniballs of a formation. Less tractive force is
responded to by strengthening of the stressed tissue (references at
section Stent-jacket Expansion Inserts). Centripetal pull-through
into the lumen can result from the improper use of the tractive
electromagnets in the muzzle-head, which are intended to recover
mispositioned or loose miniballs; tear-through.
[5388] [Air] Pump-piston--A disk closely fitted into the
longitudinal chamber behind the stay load queue that is moved by an
extension or trip connected to or continuous with the trigger or
plunger insertion mechanism, which action causes it to reciprocate.
This allows it to act as the air compressing surface of an air pump
that is used to expel the adhesive used to seal the stay insertion
incisions.
[5389] Push arm--A blank tool-insert (qv.) for nudging the
muzzle-head or radial projection catheter in the opposite direction
when extended. For increased reach (lift, distance), it is used in
a radial projection unit that incorporates a scissors lift
mechanism.
[5390] Push-through stopper--A plug used to block the entry into a
fluid injector or ejector tool-insert in order to set a threshold
line pressure for flow-through. Push-through into the syringe of
the stopper allows the tool-insert to be used as an aspirator upon
reversing the direction of flow through the fluid supply line.
Antegrade flow can be reinitiated following retrograde or
aspirative flow, but with the stopper having been removed, no
preliminary threshold pressure will precede emission. When
aspiration generates sufficient force, a 2-way slit or otherwise
perforated membrane allows directional reversal to allow actuative
or antegrade and aspriative or retrograde flow to be alternated;
break-away plug. Cf. break-seal, slit-membrane.
[5391] Quasi-intrinsically magnetized stent-jacket--A single layer
of a resilient polymer or copolymer having a magnetized particulate
dispersed through or otherwise embedded within it as matrix, such
that the one layer provides the magnetization and structural
properties required in a stent-jacket (qv.). A quasi-intrinsically
magnetized layer bonded to the base-tube of an extrinsically (qv.)
or intrinsically magnetized stent-jacket to increase its magnetic
force or resilience which is not usable independently as a
stent-jacket is a layer in a laminated stent-jacket, not a
stent-jacket. The addition of radiation shielding is by lamination,
not the additional embedding of overlapping shielding particulate
along with the magnetized particulate, shielding materials such as
tungsten paramagnetic and thus unable to provide the magnetization
needed in a stent-jacket that except for the moisture
barrier-coated viscoelastic polyurethane foam lining, consists of a
single layer. Cf. extrinsically magnetized stent-jacket;
intrinsically magnetized stent-jacket; laminated stent-jacket;
radiation shielded stent-jacket.
[5392] Radial discharge muzzle-head--A barrel-assembly (qv.)
wherein the barrel-tube or tubes (qv.) bend radially within the
muzzle-head as to be unseen, and are therefore seen to discharge at
the circumference and not, as in a simple pipe, which is exposed to
present a sharp tip as needed to obtain accurate aim in an
anatomically nonuniform or structured lumen, out the distal end. To
uncut the tunicae intima and media, the barrel or barrel-tubes are
angled forward. A radial discharge barrel-assembly is not
compatible with the use of a bounce-plate; however, the latter
would be benefit only in the airway of the smallest dogs.
[5393] Radial discharge barrel-assembly--A barrel-assembly with a
radial discharge muzzle-head (qv.). It may be of the monobarrel
(qv.) or multibarrel (qv.) kind.
[5394] Radial discharge monobarrel--A single barrel radial
discharge barrel-assembly (qv.) (radial discharge monobarrel,
radial m-barrel).
[5395] Radial projection catheter--A narrow tube (sheath, sleeve)
containing one or more radial projection system (qv.) circuits
electrical, fluidic, or both. Lacking a ballistic component (qv.),
it is not a barrel-assembly (qv.). With a central channel or
central component (qv.) which is available for insertion of a laser
or atherectomy device, it is a combination form radial projection
catheter. With a central channel that is permanently occupied by a
fiberoptic endoscope with surrounding heat-window (qv.), for
example, or is absent, it is a simple (noncombination-form,
separate, special) radial projection catheter. With the necessary
tool-inserts (qv.) installed, radial projection catheters can
ablate, angioplasty, atherectomize, inject, eject, and infuse at
any therapeutic temperature in any combination or sequence. A
radial projection catheter can have projection units situated all
along its intracorporeal length, and the units can be enlarged in
the longitudinal and circumferential dimensions. The reduction in
radial depth for accommodating projection units that results from
including a central component is therefore inconsequential; radial
projection assembly. A radial projection catheter can be used to
inject susceptible matter, to include or omit medication, into the
intima. Cf. Combination-form radial projection catheter.
[5396] Radial projection circuit--A path for conducting an
electrical or fluid current. used to power a radial projection unit
(qv.). When multiple, as in a radial projection catheter with both
electrical and fluid circuits, or addressed collectively, the
circuits are referred to as the radial projection system.
[5397] Radial projection system--An electrical or fluid circuit or
combination of such circuits with series connected lift-mechanisms
or nodes at intervals for accepting tool-inserts (qv.). The
capabilities of the two types of system and the tool-inserts these
support overlap in the use of electrical/fluid system-neutral
syringe injection and ejection tool-inserts but otherwise differ.
Cf. in-line radial projection unit, emitter, injector, radial
projection circuit.
[5398] Radial projection unit--A lifting mechansim about the
periphery of a muzzle-head for extending any of a number of
differently configured interchangeable snap-in or friction fitted
tool-inserts (qv.) radially outward toward the lumen wall. Each
unit consists of a simple or telescoping tool-insert holding
lift-platform that is raised or lowered inside a small elevation
shaft (recess, well) either electrically, by a coiled thermal
expansion wire that runs along the floor of the shaft, or
fluidically, by the pressure in a fluid line. Recession (lowering,
descent) is by reducing or shutting off the electrical or fluid
current and the urging of a spring; radial extension unit, radial
projector, radial tool elevator, tool-lift, projection unit, radial
projection node, radial projection station. Cf. [radial projection
unit] tool-insert, [radial projection unit tool-insert holding and]
lift-platform, electrical tool-insert, fluid tool-insert, in-line
radial projection unit.
[5399] Radiation shielded stent-jacket--A stent-jacket with a
radiation shield, such as of tungsten sheet, added by lamination.
The added layer is applied to a sufficient stent-jacket rather than
used to contribute greater magnetization or resilience. Cf.
extrinsically magnetized stent-jacket; intrinsically magnetized
stent-jacket; quasi-intrinsically magnetized stent-jacket;
laminated stent-jacket.
[5400] Ramrod--A tube or solid rod with a mildly magnetized tip for
retrieving a miniball accidentally discharged from the airgun
chamber with too little force to eject from the muzzle-head. A test
shaft is never magnetized, and a ramrod is never used for in situ
tissue testing; ram-rod.
[5401] Rebound lining--A shock absorbent layer applied to the
internal surface of a stent-jacket, especially one intended for
placement prior to discharge in order to avert the risk of
perforation or rebound into the lumen. The resilience of the layer
is based upon the thickness of the wall of the vessel, the angle of
entry, to which the angle of rebound will be equal in the opposite
direction, and the force of impact.
[5402] Recovery and extraction miniball electromagnet assembly--An
electromagnet or pair of tractive electromagnets at the front end
of the barrel-assembly, one in a simple pipe and two in radial
discharge barrel-assemblies for recovering loose or extracting
mispositioned miniballs. `Assembly` denotes the magnet or magnets
with housing as a distinct component. For trapping operation, or to
prevent a loose miniball from passing down the vascular or
tracheobronchial tree, these are set to a resting field strength.
When paired, the oppositely oriented electromagnets are referred to
as a magnet assembly. To allow the extraction of a miniball that
settles in an unintended position, the magnets are adjustable
together or individually; trap extraction magnet assembly (qv.),
trap and extraction electromagnet, tractive electromagnet assembly,
recovery electromagnet assembly, magnet assembly.
[5403] Recovery electromagnet--Tractive electromagnets used in
muzzle-heads and stay insertion tools (qv.) for retracting any
mispositioned or retrieving any escaped miniballs; trap-magnet;
recovery and retraction electromagnet.
[5404] [Impasse-jacket] Rim-bridge--An arm used to connect an
impasse-jacket (qv.) to its outrigger (qv.). It is preferably made
in one piece, to include a mesh edge half-rim at either end and a
cross bar connecting the two. The mesh edge half-rims are crimp
fastened and/or otherwise bonded to the mesh edges by solder, for
example.
[5405] Roof-plate--In a fluid radial projection unit (qv.), a fluid
resistor over the outlet chamber of the lifting mechanism to
restrict antegrade flow thus forcing fluid up (radially outward) to
raise the lift-platform (qv.) and in a fluid tool-insert (qv.)
causes the fluid to rise up into the tool-insert and out the
working face(qv.). Hinged along the antegrade distal edge of the
outlet chamber (qv.) to allow the inner edge of the roof-plate to
rise only to a limited extent during retrograde or aspirative flow,
the roof-plate serves both to allow debris to pass without clogging
the perforations in the plate and cause the flow of fluid to
accelerate past and thus create a drop in pressure across the mouth
or opening up into the base-plug (qv.) so that the tool-insert
functions as an aspirator.
[5406] Rotary magazine clip hole--The hole for each miniball in the
rotary magazine clip; clip hole.
[5407] Seed-core--A miniball or stay containing an irradiating seed
at its center, usually overlain with layers of related therapeutic
substances. Flatter stays distribute the radioactive content. Both
miniballs and stays can also be given a radioactive coating.
[5408] Seed-miniball--A usually gamma radiation emitting spherule
for implantion within the walls of vessels, the gastrointestinal
tract, or the airway to highly localize minimize the region
irradiated. Radiation exposure to passing blood is negligible and
short-lived. A seed miniball can be jacketed or multiply coated
with medication; miniball seed.
[5409] Seed-stay--A stay containing a radiation-emitting seed. It
may also be covered with one to several coats of medication each of
which may dissolve spontaneously or when activated by exposure to
an extreme in temperature, making possible the initiation of
delivery by the heat of a thermal or cold of a cryogenic ablation
or ablation and angioplasty-capable barrel-assembly (which can be
the same apparatus). Within the interval that the barrel-assembly
can be permitted to remain intraluminal, this makes it possible to
monitor the patient for the need of the medication before
initiating its release without its withdrawal and reintroduction;
stay-seed.
[5410] Segmented stent-jacket--A chain-stent (qv.), or sectional
stent-jacket (qv.), made from a continuous length of tubing wherein
each segment is a substent (sub-stent) continuous with the next
through a narrow bridging strip or connecting section that runs the
entire length of the tubing. The chain can be used intact, or a
certain number of substents cut off for use, or particular
substents snipped away leaving only the connecting strip. For
example, cutting away a sub-stent except for the connecting strip
allows spanning the space intervening between the proximal and
distal sub-stents (qv.) while preserving the connection between
these to counter migration. Individual sub-stents or any sequential
number thereof can be cut off for use as separate stent-jackets. An
alternative form of chain-stent (qv.) is articulated, consisting of
a train of substents (qv.) attached in a series by wires. Cf.
articulated stent-jacket, chain-stent.
[5411] Service-canal--The central or side canal in a
combination-form (through-bore, edge-discharge)
barrel-assembly.
[5412] Service-catheter--A tube that is passed down through an
unused barrel-tube used as a service-channel (qv.), to access the
muzzle-port or to penetrate into the tissue beyond the muzzle-port.
It can be used to deliver heat or cold or, with a syringe connected
at its proximal end, substances such as medication, adhesives, or
lubricants, or to withdraw tissue samples. Its distal end can be
directed at, used to swab or scrape, or to penetrate the lumen
surface.
[5413] Service-channel--A barrel-tube (qv.) or central canal (qv.)
used as a guide-catheter for a service-catheter (qv.), or as a
catheter itself. A service-channel allows access to the muzzle-head
for rapid heating or cooling. Use of a barrel-tube allows access to
the lumen wall through a muzzle-port (qv.) for delivery of a
lubricant or medication, and/or aspiration. Antiplatelet medication
or an anticoagulant can be delivered during thermal angioplasty
with heat-windows, for example; muzzle-head access barrel.
[5414] [Perforation/Radiation] Shield-jacket--1. A guard in the
form of a slit or slotted collar placed about a segment to be
discharge implanted temporarily to prevent the continued travel of
a perforating miniball, or 2. A jacket or collar for encircling a
ductus to shield against radially inward or outward radiation
whether the jacket is laminated with a magnetized layer making it a
stent-jacket. The radiation shield is generally absorbable over the
same period as shielding is required. When the ductus is to be
stented, it must be replaced with a magnetized stent-jacket. It is
used in lieu of placing the magnetized jacket at the outset only
when the jacket magnetization uncontrollably deflects or jerks
aside the muzzle-head, interfering with discharge aiming accuracy,
and the application of counterbalancing magnetic traction by the
recovery electromagnets in the muzzle-head or an extracorporeal
electromagnet do not allow the instability to be tolerated. A
shield-jacket made to counter perforations is removed immediately
following discharge and therefore omits a radiation shield, which
must be left in place until the source of radiation decays to a
level that does not require shielding, at which time it may as
appropriate, spontaneously break down, can be noninvasively
disintegrated by chemical means or heat induction, or simply left
in place. If incorporating continuous ferromagnetic material, it
can be heated to warm the segment it encircles noninvasively by
magnetic or electromagnetic induction. It consists of a slit length
of pliant tubing or base-tube (qv.), or a double-wedge (qv.) lined
base-tube. Since the most efficient radiation shield materials are
those densest and nonconductive, to additionally incorporate matter
for heat induction results in a jacket too massive for some
locations. Cf. Radiation shielded stent-jacket.
[5415] [Rotary magazine clip] Shot-group--The set of miniballs to
be discharged together from the separate hole clusters (qv.)
provided for these in the rotary magazine clip. The meaning is
unrelated to use of the term shot-group to denote a set of holes in
a target produced with a firearm set to certain aiming adjustments;
shot-group. Cf. mixed shot-group.
[5416] [Impasse-jacket] Side-access connector--A short tube
extending radially outward from an impasse-jacket (qv.) and/or one
or more of its dummy collars or outriggers (qv.) that allows a
catheter attached to an infusion set cannula or Ommaya-like
reservoir at the body surface to deliver a drug or other
therapeutic substance from a syring or portable pump, for example,
or a sample of the lumen contents to be aspirated for analysis. The
slit membrane separating the lumina of ductus and connected
catheter opens only when the threshold pressure needed to open it
is presented; side-entry connector, side-inlet, side-outlet.
[5417] Side-canal A central canal (qv.) which in order to minimize
the outer diameter of the muzzle-head is positioned at the
periphery, usually with two barrel-tubes to one side. A
combination-form barrel-assembly (qv.) for use in the bloodstream
has edge-discharge placed gas return channels allowing the central
canal to be used for inserting a commercial device such as an
excimer laser, endoscope, or rotational burr permanently or for
erchanging with other devices midprocedurally.
[5418] Side-clips--Fasteners spaced along the length of
stent-jacket and stay insertion tools (qv.) for attaching an
endoscope, lamp, laser, aspiration line, or other cabled
device.
[5419] Side-looking--Directed radially outward toward the lumen
wall from the longitudinal axis of the lumen or catheteric device,
such as a barrel-assembly or radial projection catheter.
[5420] Side-port--A side hole in the barrel-catheter (qv.) of a
barrel-assembly (qv.) or in a combination-form (qv.) radial
projection catheter (qv.). When situated in an extracorporeal
(extraductal, proximal) segment of an angioplasty-capable
barrel-assembly, the side-hole communicates with the peribarrel
space (qv.) or a pressurized gas diversion channel to serve as a
discharge pressure relief vent with or without a one-way outlet
valve. Generally larger and communicating via a frontomedially
directed tube with the central channel or (qv.) bore in a
combination-form (qv.) barrel-assembly or in a combination-form
radial projection catheter, it serves as a portal for passing
through a cabled device, such as a fiberoptic endoscope or laser
down to or through the nose or front end. In an intracorporeal
(endovascular, intraductal, distal) segment of a combination-form
barrel-assembly or a combination-form radial projection catheter, a
side-port allows blood to flow into and through the uncoccupied or
partially occupied bore or central channel (qv.) and out the
nose-hole or front end when antegrade, that is, facing into the
direction of blood flow and allows flow into the nose-hole and out
the side-port when retrograde.
[5421] Side-slit--The longitudinal cut along one side of a
stent-jacket (qv.) to allow its free expansion and contraction in
response to changes in gauge due to tonic, pulsatile, or
peristaltic forces. In a partial stent-jacket (qv.), the side-slit
is expanded to clear the attachment of the vessel or duct to
adjacent tissue following the clearing away of loose superficial
fascia; stent-jacket side-slit. Cf. slit-gap, slot-gap, expansion
insert.
[5422] Side-slot--In a stent-jacket, a side-slit that has been
enlarged to clear a connective attachment or a branch of the
ductus; a circumferential extension into a longitudinal arcuate gap
of the side-slit (qv.) sufficient to clear a ductus attachment or a
branch of the ductus; stent-jacket side-slot. Cf. slot-gap.
[5423] Side-socket--An electrical and/or fluid line connection
receptacle in an extracorporeal (extraductal, proximal) segment of
a barrel-assembly (qv.), a radial projection catheter (qv.), or
stay insertion tool (qv.). In barrel-assemblies and radial
projection catheters, it may serve, for example, to connect devices
such as the power supply in the airgun or another power supply, a
cold air gun, laser, or gas cylinder to corresponding lines within
the barrel-assembly or radial projection catheter. In an ablation
or an ablation and angioplasty-capable barrel-assembly,
side-sockets are placed in front of (distal to) or on the side or
bottom of the power and control housing hand-grip; side-connector.
In stay insertion tools, the side-socket allows connection of an
auxiliary syringe (qv.) holder or holding frame. Cf.
end-socket.
[5424] Side-straps--Hook and loop tab fastened belts (bands,
strips) on a backing of stretchable, usually spandex fabric for
girding about (cinching, binding about) the jacket surrounding the
substrate ductus rather than the ductus itself and therefore not
requiring a lining of expansion-jointed moisture barrier-coated
viscoelastic polyurethane foam and anti-migration gauze to protect
the adventitia as do end-straps (qv.) and end-ties (qv.). When the
jacket is unmagnetized, resistance to expansion of the ductus is
determined by the resilience of the base-tube if any, which is
intrinsic in the material or materials of which the base-tube is
made, and any resistance added by adjusting the tautness of the
side-straps. Side straps can be one-sided where a longer strap has
hook and loop tabs to fasten to itself or two-sided where the sides
fasten together. To allow uniform adjustment in the force of
restraint applied to an incipient aneurysm, side-straps are added
to jackets with a base-tube, but seldom to other type nonmagnetized
jackets such as perforation shield-jackets (qv.). The side-straps
connect to the jacket as do end-straps (qv.) toward either end by
means of wide-head rivets. The ability to add these, just as
expansion inserts and double-wedge insert linings, for example, to
any jacket promotes jacket standardization, reducing the cost of
production. Whether used to secure nonmagnetized or magnetless
shield-jackets, magnetized stent-jackets, clasp-jackets
(clasp-wraps), or magnet-jackets (magnet-wraps), side-straps,
end-ties, end-straps, and the links that connect substents (qv.) in
a chain-stent (qv.), for example, are all attached toward the ends
of the jacket by wide-head rivets; belt-straps.
[5425] Simple--A barrel-assembly or radial projection catheter
without a central channel or bore available to receive a cabled
device, such as an excimer laser, endoscope, rotational atherectomy
or atheroblation burr, or to allow blood to flow through.
Eliminating the bore, or minimizing the bore by permanently
installing a fiberoptic endoscope of small diameter therein, for
example, makes possible a significant reduction in outer diameter;
noncombination-form. Cf. combination-form, combination-form
barrel-assembly, combination-form radial projection catheter.
[5426] Simple impasse-jacket--A miniball impasse-jacket that
includes a single length of mesh which is magnetized at the center.
When not cushioned beneath, it must be elongated for positional
stability to resist ductus-transverse displacement (qv.) and margin
levering (:qv.) when an external electromagnet is used to extract a
miniball from the jacket. Elongation across intervening segments of
the ductus that are severely diseased, curved, must flex, or would
best be left attached are by means of bracing (qv.) or the use of a
compound (qv.) or chain (qv.) impasse-jacket.
[5427] Simple pipe [barrel-assembly]--A single barrel or monobarrel
barrel-assembly (qv.) with curved distal portion and a single
trap-miniball recovery and extraction tractive electromagnet. A
simple pipe may include a bounce plate for reversing the direction
of the trajectory. The simple pipe barrel-assembly corresponds to a
barrel-tube within a radial discharge muzzle-head (qv.) but is
independent and larger. It can be made as a single length of tubing
or as one length or segment for the main part of the
barrel-catheter, a bent segment of stainless steel, for example,
and soft elastomeric distal tip.
[5428] Simple stent-jacket--A stent-jacket (qv.) consisting of a
single segment of tubing, i.e., a stent-jacket that is not
multisegmental and jointed, or articulated.
[5429] Single [double-, triple-, quadruple-,
multiple-]-discharge--Said of a barrel-assembly with respect to the
number of barrel-tubes, hence, the number of miniballs that may be
discharged at the same time, not repeating ability.
[5430] Single jacket release--The continued delivery over time of a
magnetically susceptible drug carrier to an impasse or other type
jacket which traps the nanoparticles. A ferrobound (qv.) drug or
one bound to the susceptible component is thence drawn into the
ductus wall encircled by the jacket, while a ferro-cobound drug is
released at that level. By contrast, release and reversal paired
jackets release the drug at one level or at the inlet to an organ
by an entry jacket (qv.) and counteract or neutralize the drug at a
downstream level or at the organ outlet by an exit jacket (qv.).
The substrate tubiform structure may be a larger blood vessel,
gastrointestinal, urinogenital, or any other. Introduction is
preferably oral to allow self administration but except for
treatment along the gastrointestinal tract will usually be by
direct injection; if by infusion, the small amount of the drug
required to deliver it in high concentration for the treatment
demands high dilution. The number of potential applications for
such use of impasse-jackets with or without a reversal exit jacket
(qv.) by type, much less specifically, are myriad. Multiple or
array jacket release with or without a terminal or exit-jacket to
eliminate the drug or its ability to act at a certain point or
level require the graduated distribution among jackets of the
carrier-bound drug or drugs by varying the magnetic strength of the
jackets and/or the magnetic susceptibility of the carriers along
the treated segment Cf. Single stage magnetic drug-targeting,
paired jacket release and neutralization.
[5431] Single stage magnetic drug-targeting--The use of an
impasse-jacket, stent-jacket, or magnet-jacket to draw
ferromagnetic or superparamagnetic drug carrier nanoparticles
passing through the lumen through the endothelium and into the
lesion or neoplasm, for example, in the lumen wall. The most
obvious example is placement about an artery to draw medication
into an atheromatous lesion. Cf. Multistage magnetic
drug-targeting.
[5432] Slit-gap--The distance separating the edges of the side-slit
(qv.) in a stent-jacket (qv.). When the slit-gap is temporarily
lengthened due to the use of an expansion insert (qv.), the out of
round (eccentricity) running its length and just inside the
base-tube (qv.) is taken up with strips of additional moisture
barrier-coated viscoelastic polyurethane foam supplied along with
the expansion strips that come with the stent-jacket. Cf.
slot-gap.
[5433] Slit-membrane--An elastic film used as a two-way or
bidirectional fluid resistor. Slit-membranes can be used at the
proximal end of the central canal (qv.) of a barrel-assembly (qv.)
or in the base-plug (qv.) of a fluid tool-insert. By contrast, a
break-seal(qv.) or a push-through stopper (qv.) is one-way
(unidirectional). A two-way resistor allows reversal in the
direction of the fluid flow through the circuit more than once so
that retrograde or aspirative flow can alternate with actuative or
antegrade flow repeatedly.
[5434] Slitting edge--A retractable razor edge used with a recovery
electromagnet to assist in freeing a stay meant for temporary
implantation, such as a radiation emitting seed of dose-rate higher
than is left in place. When the stay insertion tool (qv.) lacks a
bottom end-pivot (qv.) or tilting base-end, the slitting edge is
retracted into the butt of the tool. In a tool with an end-pivot,
the edge is retracted into the butt-pad that can be used to nudge
the butt to a side using neighboring tissue to avoid the need for
repeated intracorporeal withdrawal and reentry.
[5435] Slot-gap--The distance separating the edges of the side-slot
(qv.) in a stent-jacket (qv.). When the slot-gap is temporarily
increased due to the use of an expansion insert (qv.), the out of
round (eccentricity) running its length and just inside the
base-tube (qv.) is taken up with strips of additional moisture
barrier-coated viscoelastic polyurethane foam supplied along with
the expansion strips that come with the stent-jacket. Cf.
slit-gap.
[5436] Slotted stent-jacket--A stent-jacket (qv.) having a
longitudinal arc of the base-tube (qv.) removed to accommodate a
running connective tissue attachment along one side of the vas or
ductus stented.
[5437] Spindle--The middle portion of the muzzle-head that receives
the barrel-tubes and continues these toward the muzzle-ports as the
barrel channels. It is usually machined from a single piece of
nonmagnetic stainless steel, then through-hardened.
[5438] [Muzzle-head] Spindle neck--The portion of the spindle that
is journaled within the rotor of the turret-motor.
[5439] [Muzzle-head] Spindle throat--the portion of the muzzle-head
spindle between the neck journaled within the rotor of the
turret-motor and the ejection-head.
[5440] Spine and ribs-configured stent-jacket--A stent-jacket (qv.)
specially configured to comply with peristalsis along the digestive
tract. It can be used to retract the lumen wall radially outward
and/or to draw magnetically susceptible drug carrier nanoparticles
from a swallowed ferrofluid into a tumor along the esophagus, for
example, to accomplish the drawing against or into the lumen wall
of a drug, or effect magnetic assisted transfection of small
interfering (short interfering, silencing) ribonucleic acid into a
tumor, for example; rib-jacket.
[5441] Splay chamber--In the proximal portion of a muzzle-head, a
cavity distal to the collar securing the muzzle-head to the distal
end of the barrel-catheter that allows the barrel-tubes to bend or
veer radially outward toward the muzzle-ports gradually as not to
kink; barrel-tube splay-chamber.
[5442] Start of segment--The proximal or upstream starting level as
the starting point for the exposure of a defined length or segment
of a ductus to the action of an active drug and/or other
therapeutic substance. It is established by injecting or infusing
the active substance or by placement of an entry impasse-jacket
(qv.), or entry jacket (qv.), containing the drug in inactive form
until it is activated at at the start of segment entry jacket as
the result of the injection of a drug-activating substance
upstream. That is, when the physiologically active substance is
introduced upstream, that marks the start of segment; when a
substance is injected upstream to activate a drug downstream, the
latter marks the start of segment. The active drug is usually in
the form of a ferrofluid that contains drug carrier particles. When
incorporated into a shell such as a microsphere or miniball, the
particles are released when the shell breaks down, either by
spontaneous (unaided) dissolution or as the result of injecting a
breakdown inducing substance upstream. Cf. end of segment.
[5443] [Arcuate] Stay--An slightly bowed or arcuate rib or band for
insertion into a collapsing or stenotic ductus to correct the
condition. A stay that contains ferromagnetic material such as a
core of soft iron for implantation into a ductus wall so that the
wall will be retracted by an encircling stent-jacket carrying
permanent magnets on its outer surface is a stent-stay. Stays
lacking ferrous metal that consist of medication, contain an
irradiating seed, or that encapsulate a seed with medication are
used without a stent-jacket for the purpose of delivery that is
local rather than systemic and concentrated are referred to simply
as stays. Stays containing ferrous metal for use with a magnetic
stent-jacket to expand (retract, destenose, uncollapse) a ductus
are referred to as stent-stays; stent-ribs, ribs. Cf. miniball,
medication stay, medicated miniball, medicatd stay.
[5444] Stay insertion incision--The incision made through the outer
layer (tunica adventitia, tunica fibrosa) of the ductus by the stay
when inserted subadventitially or medially, not the previous
incision made to access the ductus from outside the body, which is
the stay entry incision (qv.); stay injection incision.
[5445] Stay insertion tool--A syringe (push-type) or pistol
(pull-type)-configured hand tool for inserting stent or other kinds
of stays (qv.) such as drug containing perimedially
(subadventitially) or medially through the outer surface and into
the wall of a ductus by incisional entry; stay insertion tool, stay
infixion tool, stay inserter. Stay insertion tools may be manually
operated, but coordinated use of stay coating devices will then
require the use of both hands. For this reason, most stay insertion
tools incorporate an embedded microcontroller to control all
aspects of the stay ejection cycle (qv.) except initiation of each
ejection or triggering by the operator. since to coordinate the of
the ejection cycle.
[5446] Stay insertion tool base--The parts along the bottom or
distal working end, of a stay insertion tool (qv.), of which the
front portion or foot, which is bonded to the front of the tool
barrel is stationary and rested upon the ductus, while the rear
portion or butt is depressed during the loading phase or stroke,
and raised during the ejection phase of the stay ejection cycle
(qv.). These comprise a forward portion or foot, and a rear portion
or butt. The front of the foot is the toe, the rear the heel, and
the middle, the sole. The distal tip of a cement or medication
delivery line terminates just above the front opening of the stay
ejection slot at the toe. The foot continues rearward as the sole,
the rear edge of which is the heel, situated just below the entry
opening into the stay ejection slot. The stay ejection tongue drops
down to the butt where it is rivetted as the forward element of the
butt. The butt consists of the ejection tongue at the front, distal
end of the thumb plunger-rod in the middle and distal tip of the
magnet probe at the rear, these three elements fastened together by
means of a rivet that passes through these and ferrules used to
space these three elements apart.
[5447] [Stay insertion tool] ejection cycle--The coordinated
sequence and timing of component actions in the operation of a stay
insertion tool (qv.), comprising loading and ejection phases or
strokes. Since the application of cement and medication usually
need to be coordinated with stay insertion (injection), means are
provided for accomplishing the synchronized unloading of the cement
delivery line internal to the tool. With a mechanical embodiment,
so long as the inmate stay coating mechanism is engaged by rotating
the thumb plunger rod, depressing and releasing the spring-returned
thumb-ring and plunger-rod will effect stay coating automatically,
the inmate stay coating means then connected as a slave follower.
However, were the magnetic strength left high and the operator to
withdraw the tool from the insertion site prematurely so that the
cyanoacrylate cement had not sufficient time to prevent retraction
of the stay with the blade, or were an auxiliary syringe to be
incorporated into the ejection cycle, for example, unless the
magnetic strength were reduced, the stay could stick to and be
retracted by the stay ejection blade. However, to lower the
magnetic field force, the operator must use both hands. To avoid
the need for 2-handed coordination, avert any excess or reduction
in the release of medication or sealant from the inmate or an
attached auxiliary syringe due to abrupt thumb plunger-rod
downstroke or return by the operator, and to place the operation of
an auxiliary syringe (qv.) under ejection cycle-coordinated rather
than independent control when desired, more versatile embodiments
incorporate an embedded microcontroller to govern all aspects of
the cycle except actuation.
[5448] [Stay insertion tool auxiliary syringe] Holding frame--A
brace or arm for attaching and controllably unloading, or emptying
over an interval adjustable in initiation and duration, an
auxiliary syringe (qv.) or syringes containing a tissue sealant or
medication; [syringe] holder.
[5449] Stent-implant--A miniball (qv.) or stay (qv.) with
ferromagnetic core that has been infixed within the wall of a
ductus for retraction by a stent-jacket (qv.). When the implants
are miniballs, which are implanted ballistically, and vulnerable
structures surround the ductus that could be injured were a
miniball to penetrate entirely through the wall of the ductus, a
double-wedge stent-jacket (qv.) that deflects such an otherwise
penetrating discharge to an acceptable location in the wall of the
ductus is placed first.
[5450] Stent implantation--The placement of ferromagnetic miniballs
(qv.) or stays (qv.) in the wall of a ductus for retraction by a
stent-jacket (qv.).
[5451] Stent-jacket--The extraductal (circumductal, periductal,
circumvascular, perivascular) component, or base-tube, of an
extraluminal stent. A full or fully round stent-jacket entirely
surrounds the vessel or duct, whereas a partial stent-jacket
encloses only that circumferential extent of the vessel or duct
that is exposed without the need to dissect a line of connective
tissue that attaches the structure to another or to avoid a branch
such as one that plunges to greater depth. Stent-jackets are also
characterized as magnetic or magnetless, the former sometimes in
the form of a chain or made up of a series (train, string) of
separate stents. To minimize the effect of the extraluminal stent
upon relatively undiseased portions of an eccentric angiosclerotic
lesion, the complete or partial extraluminal stent can be blanked
out for the unaffected arcuate segment. In a magnetic stent-jacket,
this is accomplished by using a rotary magazine clip in the chamber
of the interventional airgun that has the miniball loading holes
for the the unused sector empty (blank) and omitting the implanting
of miniballs and positioning bar magnets in this segment. In a
magnetic stent-jacket, limited areas are cut out as necessary. A
magnetic stent-jacket is a kind of magnet-wrap (qv.) in the literal
sense, but incorporates a resilient base-tube as substrate rather
than gauze and a biocompatible stretchable fabric such as spandex
and thus is not a kind of bandage or wrap-surround. Cf. magnetic
stent-jacket; chain-jacket; magnetless stent-jacket; extrinsically
magnetized stent-jacket; intrinsically magnetized stent-jacket;
laminated stent-jacket; radiation shielded stent-jacket.
[5452] Stent-jacket applicator--A tool, usually a hand-tool, for
opening the stent-jacket for encircling the substrate ductus. It
may be designed for ease of use endoscopically or robotically
rather than manually; base-tube retractor, side-slit retractor,
side-slot retractor, stent-jacket expander.
[5453] Stent shot-group--An aggregation of miniballs implanted in
close formation to prevent pull-through (qv.).
[5454] Stent-stay--A band of ferromagnetic metal cambered for
concentricity with the ductus into which it is to be inserted
subadventitially (perimedially) by means of a special insertion
tool for retraction of the ductus wall by an encircling
stent-jacket. Stays that do not include concentrated ferromagnetic
matter are simply stays, not stent-stays.
[5455] Stereotactic or stereotaxic extraction--The immediate
resituation to a safe location or removal of an ischemiatizing, or
the interception of a potentionally embolizing miniball that cannot
be readily dissolved or destroyed. The recovery electromagnets
(qv.) and trap-filter (qv.) built into the muzzle-head make the
need for an emergency bail-out or last measure unlikely. To assure
retrievability, insoluble miniballs include encapsulated grains of
iron powder and dissoluble miniballs superparamagnetic magnetite or
maghemite. A high field strength external electromagnet or MRI
machine is used to withdraw the miniball along a path calculated to
least affect intervening structures and thus minimize trauma.
Forcible magnetic extraction is generally into the proximate body
cavity, skeletal muscle, or other relatively safe nearby location
where the minute, sterile, and biocompatible miniball can usually
remain. Extraction completely out of the body is rarely
contemplated. If necessary, the Ba magnetic resonance imaging
machine is used to draw the miniball out to the exterior through
the intervening tissue; stereotactic recovery.
[5456] Stop-and-lock ring--A nonmagnetic metal annulus about the
barrel-catheter that fixes the distance that the barrel-assembly
can be pushed into the barrel of the airgun. Tabs that project from
the ring periphery fit into slots within a complementary fitting
affixed to the airgun muzzle. These tabs slide through ways to
engage the barrel-assembly to the airgun. With tabs twisted into
the rotary slideway in the female component of the twist-to-lock
connector (qv.), the barrel-assembly is locked in position with its
proximal end immediately before the face of the rotary magazine
clip or miniball to be discharged and in the correct alignment.
[5457] Striking-point--The locus or spot where the miniball impacts
against the target tissue.
[5458] Stopping-magnet--A magnet prepositioned to stop a miniball
from continued movement, usually, through the bloodstream. A
stopping-magnet used midprocedurally is usually a powerful
adjustable external electromagnet that allows the miniball to be
stopped and stereotactically extracted through the lumen wall and
into a safe location, or if necessary, removed from the body.
Postprocedural stopping magnets are usually mounted on special
miniball-impasse-jackets (qv.) fitted to the same ductus and
configured to least interfere with miniball removal; otherwise,
such magnets are mounted to an adjacent structure on a
magnet-jacket or patch-magnet. Since the miniball to ductus ratio
decreased as the miniball travels downstream in an artery, for
example, an effort is made to position stopping-points as proximal
to the insertion points as possible; backup magnet, holding
magnet.
[5459] Stopping-point--The position and level or aiming point of a
stop-magnet (qv.) probe. Proximity to the point or point intended
of implant insertion stops the miniball while it is smallest
relative to the lumen and makes the proportionally smallest
extraction perforation if removed by means of stereotactic
extraction (qv.).
[5460] Subadventitial--just within the external elastic lamina or
tunica adventitia as the outer layers of a ductus; perimedial.
[5461] Straight-line lining--A lining for a stent-jacket (qv.),
which in contradistinction to a double-wedge insert as the
alternative, omits an outer resilient bounce-wedge (qv.) about the
moisture barrier-coated viscoelastic polyurethane foam. The foam is
noninclined but rather disposed parallel to the ductus. Either a
straight-line or double-wedge type lining can be inserted along
with an expansion insert if necessary upon manufacture or by the
operator; parallel lining.
[5462] Strike-point--The spot on a bounce-plate (qv.) where the
miniball impacts and is rebounded. When rotated concentrically
about the long axis of the barrel-assembly and muzzle-head, the
trajectories of the successively discharged and rebounded miniballs
describe a conical pattern where the strike-point is revolving a
distance short of the cone apex and the circular formation of
miniballs describes the base of the cone. Since the strike-point
establishes the trajectory for rebound whether it is revolved when
the muzzle-head is rotated or the bounce-plate is rotated about its
own long axis, the latter movement draws the trajectories of the
miniballs inward relative to the base of the cone. This allows the
operator to nudge the miniballs slightly inward of the larger
cycle.
[5463] Substent [-jacket]--One component stent-jacket (qv.) in a
chain- (serial, compound) stent-jacket. When linked in an
articulated stent-jacket (qv.), the connecting wires can be snipped
and when a segment in a segmented stent (qv.), the connecting band
can be cut with scissors midway between the side-straps at either
end to provide a unit stent. Stent-jackets could be routinely
marketed as chain-stents.
[5464] Substrate [ductus]--The vessel or ductus mantled about by a
stent-jacket (qv.), clasp-wrap (qv.), or magnet-wrap (qv.).
[5465] Suture loop or suture eyelet--Small optional handles
integral with the stent-jacket for passing through suture in order
to stabilize the stent-jacket in position by attachment to
neighboring tissue in locations where pronounced vasotonic,
peristaltic, and/or bodily movement might otherwise cause the
stent-jacket to become displaced, or migrate.
[5466] Swelling agent--A substance used to temporarily increase the
thickness of a ductus wall to make implantation less difficult;
tumefacient, swellant.
[5467] Swing over lock down arms--Bars that rotate to engage and
hold a tool-insert within the tool-insert holding and lift-platform
(qv.).
[5468] Swivel-motor--The motor used to rotate the muzzle-head in a
single barrel or monobarrel radial discharge barrel-assembly,
wherein rotation is of one centered or axial barrel-tube, rather
than two or more barrel-tubes radial to the central axis; single
barrel turret-motor; single barrel turret-servomotor.
[5469] Syringe ejector--An ejection tool-insert (qv.). Mechanical
ejectors are electrical-fluidic radial projection system-neutral,
whereas electrical ejectors are usable only in electrical systems
and fluidically operated ejectors are usable only in fluidic
systems; syringe ejection tool-insert. Cf. emission tool-insert,
emitter.
[5470] Syringe injector--A hollow needle or inoculation-type device
used to deliver a limited volume of a drug or cement, for example,
into or outside the inner lamina of the lumen wall. Mechanical or
spring-released injectors are electrical-fluidic radial projection
system-neutral, whereas electrical injectors are usable only in
electrical systems and fluidic injectors are usable only in fluidic
systems. Fluidically operated injectors can deliver an prefilled
dose, then continue with fluid from the supply line; syringe
injection tool-insert. Cf. emission tool-insert, emitter.
[5471] Tablet miniball--A spherule for ballistic implantation,
usually into the wall of a ductus, that consists of homogeneous or
layered medication. It can include a radiation emitting core. In
contrast to a medicated miniball, (qv.), it is not usable for
magnetic stenting (qv.). Cf. medicated miniball, medication stay,
tablet stay.
[5472] Tablet stay--An arcuate stay (qv.) or rib for implantation,
usually into the wall of a ductus, that consists of homogeneous or
layered medication. It can include a radiation-emitting core or
seed. In contrast to a medicated stay (qv.), it is not usable for
magnetic stenting (qv.); medication stay. Magnetically susceptible
matter, usually superparamagnetic magnetite or maghemite
nanoparticles or finely grained powder, is incorporated only if
loss within the body poses some risk that makes necessary its
retrievability with the aid of a powerful magnet. Cf. medicated
stay, medication miniball, tablet miniball.
[5473] Temporary implant--A midprocedural protective device, such
as a shield-jacket (qv.), placed temporarily to prevent a
perforation during discharge and removed before closure. Opposed to
an end-implant, such as a magnetic stent-jacket (qv.), that will
remain in position after closure. Implants completely or partially
absorbed after closure, such as radiation shield-jackets, are never
removed and therefore not characterized as temporary but rather
nonpermanent end-implants. The term applies to the manner of use of
the implant, not to anything intrinsic in it, so that a
shield-jacket placed for postprocedural warming by heat-induction
at any later date, for example, is not a temporary but rather an
end-implant. Cf. temporary implant.
[5474] Test shaft--A solid rod or tube (catheter) placed in a
barrel-tube to take the place of an implant projectile in order to
allow the penetrative force corresponding to the exit velocity to
which the airgun is set to be evaluated.
[5475] Thumb-ring--In a control-type syringe configured stay
insertion tool (qv.), the annulus surrounding the thumb hole. To
allow immediate access by touch, controls for auxiliary syringes
are mounted about it.
[5476] Thumb switch--In a stay insertion tool, a switch mounted to
and facing or conveniently situated relative to the thumb of the
operator for the immediate manual control of any electrically
powered auxiliary function, to include the use of an attached
medication or tissue cement dispensing syringe holding frame,
suction line, or laser. On the grip of a modified commercial air
pistol, a switch situated for immediate use by the thumb.
[5477] [Impasse-jacket] Tie-downs--Lengths of suture looped around
a peripherally directed (operator-facing) mesh strand (wire,
gridline) or strands overlying the foam end-cuffs (qv.) of an
impasse-jacket (qv.), and the end-cuffs of any unmagnetized
dummy-collars, or outriggers (qv.), to fix the impasse-jacket to
neighboring (usually underlying or subjacent) tissue for positional
stability during an extraction. Tie-downs prevent forceful
impasse-jacket ductus-transverse displacements (qv.) and
margin-levering (qv.) of the encircled ductus (usually an artery)
into a subjacent space or against ineffectively cushioning or hard
tissue during an extraction under the repulsive force of the
external extraction electromagnet (qv.). Such movement can wrench
the ductus at the end-edges or margins of the impasse-jacket,
causing trauma that can lead to restenosis. The suture must not
more than mildly bend the ductus at the margins or be so tight that
it impairs compliance of the jacket to the pulse or if applied to
another type ductus, then the intrinsic muscle action appurtenant
thereto. Infirm support from beneath may justify the interposition
of a biocompatible cushion as a prop (bolster pad). Cf.
[impasse-jacket] ductus-transverse displacement, ductus-normal
displacement, margin-thrust, bracing, chain impasse-jacket,
chain-guard, chain holding jacket.
[5478] [Radial projection unit] Tool-insert--A cutting, abrading,
aspirating, gas-ejecting, spraying, or injecting modular working
implement for engagement in a tool-holding and lift-platform (qv.)
of a radial projection unit (qv.). The insert can also be a blank
used as a pushing arm or a plug that disables lifting in that unit.
Functionally diverse tools interchangeably fit the opening in a
tool-insert holding lift-platform (qv.) of given dimensions.
Tool-inserts that require connection to a power source are
enertized either electrically or fluidically. Cf. ejector,
injector, syringe injector, fluid tool-insert, electrical
tool-insert, radial projection system, in-line radial projection
unit.
[5479] Tool-insert holding and lift-platform--The receptacle for
retaining interchangeable tool-inserts in the lift-shaft of a
radial projection unit (qv.).
[5480] Track--A longitudinal line along a rotational angle about
the circumference of a ductus wall for implantation or the implants
situated along such a line.
[5481] [Miniball] Trap-jacket--An impasse-jacket (qv.) whether
simple (qv.) and used in isolation, or braced (qv.), or a component
in a compound or a chain impasse-jacket. A trap is used to seize a
miniball or miniballs from further passage through the bloodstream
(simple-guard, simple guard-jacket, simple trap-collar,
simple-trap).
[5482] Trap-extraction magnet assembly--An electromagnet or pair of
electromagnets mounted to the front of the muzzle-head, of which
the individual or combined field strengths can be varied to prevent
the escape of miniballs downstream or to retract miniballs that
have already been implanted. It is unitized with and integral to
every muzzle-head; miniball recovery and extraction tractive
electromagnet assembly; recovery electromagnets, retrieval
electromagnets, tractive electromagnets, trap-magnet.
[5483] Trap-filter--An embolic filter adapted for installation in
the nose of an angioplasty-capable barrel-assembly (qv.), usually
at the center of a nose heat-window that surrounds it. That is, a
miniature filter having the form of a trawling type fishing net,
windsock, parachute, or umbrella that is used with shaving or
abrading radial projection unit tool-inserts, for example, to
prevent distal embolization by intercepting any angioplasty
produced debris or a miniball that midprocedurally escapes
downstream. The trap-filter is deployed from and withdrawn into a
concavity by a miniature dc plunger solenoid set into the
muzzle-head nose (qv.). It can be purchased as a commercial product
and adapted for incorporation into the nose of the muzzle-head;
embolic filter, run-ahead filter, run-ahead trap-filter,
filter-trap. Cf. magnet-trap.
[5484] Trapping [field] intensity--the low or resting magnetic
field strength of the miniball recovery tractive electromagnets
used to trap any miniballs that fall into the lumen; trapping field
strength.
[5485] [Muzzle-head] Turret-motor--In a mono- or multibarrel radial
discharge barrel-assembly, the motor used to rotate the muzzle-head
at the rotary joint connecting the muzzle-head to the
barrel-catheter. Rotation of the off-center barrel-tubes twists
these, so that the motor must be limited to an arc through which
the barrel-tubes do not deform causing jams upon discharge;
t-motor, turret-servomotor, rotation servomotor.
[5486] Twist-to-lock connector--A connector consisting of a male
with sliding tabs stop-and-lock ring (qv.) mounted about the
barrel-catheter at the distance from the end-plate (qv.) to which
the barrel-catheter is to be inserted into the airgun barrel, and a
female fitting mounted to the front of the airgun muzzle having
slots and channels in which the tabs of the stop-and-lock ring are
slid around beneath a compressive ceiling until stopped from
further rotation. This connects the barrel-assembly to the airgun
at the correct rotational angle. In an angioplasty barrel-assembly,
the twist-to-lock connector serves as the proximal stop for the
hand-grip shaped power or battery pack and control housing when
slid back to perform an angioplasty prior to inserting the
barrel-assembly in the interventional airgun for stenting; twist to
engage connector, twist lock connector.
[5487] Working arc--the range of muzzle-head rotation to either
side of the center reference point or zero angle of turret-motor
rotation as limited by the inception of discharge-obstructive
deformation of the barrel-tubes in use, hence, the arc through
which the turret-motor is limited in rotating a specific
muzzle-head. To rotate the muzzle-head outside this arc
necessitates rotation of the barrel-assembly as a whole
intraluminally and at the rotating flange component of the
twist-and-lock connector affixed to the muzzle of the airgun.
[5488] Wrap-surround--A special bandage used to position magnets or
ferromagnetic miniballs around a tubular anatomical structure. One
mounting miniballs is a clasp-wrap (qv.), which is used when the
ductus wall is incapable of being implanted with or retaining
miniballs. It is in turn surrounded by a stent-jacket (qv.). One
mounting magnets used to exert patenting tractive force upon the
miniballs implanted in a neighboring, usually parallel, structure
is a magnet-wrap (qv.), which serves in lieu of an immediate
stent-jacket. A stent-jacket provides a firm platform to which the
ductus-intramural implants are attracted and is not a kind of
bandage or wrap-surround.
* * * * *
References