U.S. patent application number 16/450355 was filed with the patent office on 2019-10-10 for system and method for positioning implantable medical devices within coronary veins.
The applicant listed for this patent is Medtronic, Inc.. Invention is credited to Eric K.Y. Chan, Kenneth C. Gardeski, James F. Kelley, Mohmoud K. Seraj, Stanten C. Spear.
Application Number | 20190307988 16/450355 |
Document ID | / |
Family ID | 29268731 |
Filed Date | 2019-10-10 |
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United States Patent
Application |
20190307988 |
Kind Code |
A1 |
Spear; Stanten C. ; et
al. |
October 10, 2019 |
SYSTEM AND METHOD FOR POSITIONING IMPLANTABLE MEDICAL DEVICES
WITHIN CORONARY VEINS
Abstract
An improved system and method for placing implantable medical
devices (IMDs) such as leads within the coronary sinus and branch
veins is disclosed. In one embodiment, a slittable delivery sheath
and a method of using the sheath are provided. The sheath includes
a slittable hub, and a substantially straight body defining an
inner lumen. The body comprises a shaft section and a distal
section that is distal to, and softer than, the shaft section. A
slittable braid extends adjacent to at least a portion of one of
the shaft section and the distal section. In one embodiment of the
invention, the sheath further includes a transition section that is
distal to the shaft section, and proximal to the distal section.
The transition section is softer than the shaft section, but
stiffer than the distal section.
Inventors: |
Spear; Stanten C.; (Arden
Hills, MN) ; Kelley; James F.; (Coon Rapids, MN)
; Gardeski; Kenneth C.; (Plymouth, MN) ; Seraj;
Mohmoud K.; (Apex, NC) ; Chan; Eric K.Y.;
(Newark, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic, Inc. |
Minneapolis |
MN |
US |
|
|
Family ID: |
29268731 |
Appl. No.: |
16/450355 |
Filed: |
June 24, 2019 |
Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
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14283303 |
May 21, 2014 |
10328243 |
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16450355 |
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12357810 |
Jan 22, 2009 |
8734397 |
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14283303 |
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10131436 |
Apr 25, 2002 |
7497844 |
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12357810 |
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09822678 |
Mar 30, 2001 |
6743227 |
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10131436 |
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60193695 |
Mar 31, 2000 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 2025/0681 20130101;
A61N 2001/0585 20130101; A61N 1/056 20130101; A61M 25/0668
20130101; A61M 2025/0161 20130101; A61M 2025/1052 20130101; A61M
25/0051 20130101; A61B 2018/00386 20130101; A61B 2017/22038
20130101; A61M 2025/0081 20130101; A61M 2025/0042 20130101; A61M
2025/1079 20130101; A61M 25/0138 20130101; A61N 2001/0578 20130101;
A61M 2025/0047 20130101; A61M 25/0147 20130101; A61M 25/0054
20130101; A61M 25/0141 20130101; A61M 25/008 20130101; A61B 18/1492
20130101; A61M 25/005 20130101 |
International
Class: |
A61M 25/06 20060101
A61M025/06; A61M 25/01 20060101 A61M025/01; A61M 25/00 20060101
A61M025/00; A61N 1/05 20060101 A61N001/05; A61B 18/14 20060101
A61B018/14 |
Claims
1-37. (canceled)
38. A system for positioning implantable medical devices within the
coronary sinus or a branch vein thereof, comprising: a
substantially straight slittable sheath comprising a central lumen,
a shaft section, and a distal section that is distal to, and softer
than, the shaft section, the sheath further comprising a slittable
braid adjacent to at least a portion of at least one of the shaft
section and the distal section; a balloon catheter adapted to be
inserted within the central lumen of the sheath, the balloon
catheter comprising an elongated shaft defining an inner lumen; and
a steerable catheter having a shaft adapted to be inserted within
the inner lumen of the balloon catheter.
39. The system of claim 38, wherein the balloon catheter further
comprises an inflation lumen and an occlusion balloon fluidly
coupled to the inflation lumen.
40. The system of claim 38, wherein the elongated shaft of the
balloon catheter has an outer diameter ranging from approximately
0.050 to 0.100 inches.
41. The system of claim 38, wherein the elongated shaft of the
balloon catheter has an outer diameter of approximately 0.074
inches.
42. The system of claim 38, wherein the inner lumen of the balloon
catheter has an inner diameter ranging from approximately 0.030 to
0.080 inches.
43. The system of claim 38, wherein the balloon catheter further
comprises a heat shrink tubing disposed on an outer surface of a
shaft proximal section.
44. The system of claim 38, wherein the balloon catheter further
comprises a distal tip disposed at a distal end of the elongated
shaft, and wherein the distal tip is formed of a flexible polymeric
material.
45. The system of claim 44, wherein the distal tip of the balloon
catheter is radiopaque.
46. The system of claim 38, wherein the balloon catheter further
comprises a distal tip, a distal section, and a proximal section,
and wherein a total length of the distal tip, the distal section
and the proximal section is approximately 50 to 90 centimeters.
47. The system of claim 38, wherein the balloon catheter comprises
PEBAX tubing having a hardness ranging from approximately 60D to
80D (Shore).
48. The system of claim 38, wherein the balloon catheter further
comprises an occlusion balloon having an inflated diameter ranging
from approximately 0.2 to 1.0 inches.
49. The system of claim 48, wherein the occlusion balloon has a
wall thickness ranging from approximately 0.002 to 0.006
inches.
50. The system of claim 48, wherein the occlusion balloon has
length ranging from approximately 6 to 14 millimeters.
51. A catheter assembly for positioning implantable medical devices
within the coronary sinus or a branch vein thereof comprising: a
sheath apparatus comprises a substantially straight slittable
sheath extending from a proximal end to a distal end defining an
inner lumen, wherein the slittable sheath comprises a shaft
section, a distal section distal to the shaft section at the distal
end of the sheath, wherein the distal section comprises a soft tip
extending from a transition location along the distal section to
the distal end of the sheath, and a slittable braid extending along
the shaft section and at least a portion of the distal section, and
an internal liner adjacent at least a portion of the inner lumen
and extending along the shaft section and terminating within the
distal section of the sheath beyond the distal end of the slittable
braid; a balloon catheter adapted to be inserted within the central
lumen of the sheath, the balloon catheter comprising an elongated
shaft defining an inner lumen and a balloon disposed along the
elongated shaft; and a steerable catheter having a shaft adapted to
be inserted within the inner lumen of the balloon catheter.
52. The assembly of claim 51, wherein the balloon catheter further
comprises a distal tip disposed at a distal end of the elongated
shaft, and wherein the distal tip is formed of a flexible polymeric
material.
53. A method for seating an implantable medical device within a
coronary sinus or branch vein of a patient, the method comprising:
a.) providing a slittable sheath having a substantially straight
sheath body defining a central lumen, wherein the sheath body
comprises: a shaft section and a distal section, wherein the shaft
section is formed of a first material and the distal section is
formed of a second material, and wherein the first material is more
rigid than the second material; and a slittable braid extending
adjacent to at least a portion of one of the shaft section and the
distal section; b.) inserting a balloon catheter within the central
lumen of the slittable sheath, the balloon catheter comprising
defining an inner lumen; c.) inserting a steerable catheter within
the inner lumen of the balloon catheter; d.) positioning the
slittable sheath, the balloon catheter, and the steerable catheter
within a passageway of the patient; and e.) navigating the
slittable sheath, the balloon catheter, and the steerable catheter
into the coronary sinus.
54. The method of claim 53, wherein step e.) comprises: advancing a
distal end of the steerable catheter beyond a distal end of the
slittable sheath; cannulating the coronary sinus with the steerable
catheter; and withdrawing the steerable catheter from the coronary
sinus.
55. The method of claim 53, and further comprising: obtaining a
venogram; and withdrawing the balloon catheter from the central
lumen of the slittable sheath.
56. The method of claim 53, and further comprising: f.) advancing
an implantable medical device within the central lumen of the
slittable sheath.
57. The method of claim 56, wherein the step f) further comprises:
advancing a navigational device within the central lumen of the
slittable sheath.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/357,810, filed Jan. 22, 2009 entitled
"IMPROVED SYSTEM AND METHOD FOR POSITIONING IMPLANTABLE MEDICAL
DEVICES WITHIN CORONARY VEINS", herein incorporated by reference in
its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to a system and method for
mammalian intralumenal visualization and delivery of various
devices or agents into a targeted area of the body. More
particularly, this invention relates to a visualization and
delivery system for accurately placing devices such as leads,
electrophysiology catheters, and therapeutic agents into
large-organ vessel systems such as the coronary vasculature.
[0003] In treating conditions such as arrhythmia, one technique is
to destroy or damage heart tissue that causes or is involved with
the arrhythmia by suitably heating the tissue, e.g., by applying a
laser beam or high-frequency electrical energy such as
radio-frequency (RF) or microwave energy.
[0004] For such treatment to be effective, the location of the
tissue site causing or involved with the arrhythmia must be
accurately determined in order to be able to contact heart tissue
adjacent the desired location with a tissue-destroying device. A
high degree of accuracy in determining this site is paramount so
that an excessive amount of viable tissue is not destroyed adjacent
the site. For example, the average arrhythmogenic site consists of
about 1.4 cm.sup.2 of endocardial tissue, whereas a re-entrant site
might be much larger. RF ablation techniques produce lesions about
0.5 cm.sup.2 of diameter, so a number of lesions are typically
generated in order to ablate the area of interest. If the site is
not accurately mapped, much of the viable tissue surrounding the
site will be unnecessarily destroyed.
[0005] To determine the location of the tissue to be ablated, it is
widely known to use elongated intravascular signal sensing devices
that are advanced through the patient's vasculature until the
distal portions of the device are disposed within one or more of
the patient's heart chambers, with one or more electrodes on the
distal portion of the device in contact with the endocardial
lining. Such devices may also be advanced within a patient's
coronary artery, coronary sinus, or cardiac vein. Sensing devices
such as those disclosed in U.S. Pat. No. 5,967,978 to Littmann et
al., and combination sensing-ablation devices such as those
disclosed in U.S. Pat. No. 6,002,956 to Schaer are typical.
[0006] Guiding catheters such as those disclosed in U.S. Pat. Nos.
6,021,340 and 5,775,327 to Randolph et al. may be used to rapidly
advance such devices into a patient's cardiac vein draining into
the coronary sinus. A particular advantage of the catheters
disclosed in these references is the presence of an inner lumen and
distal port on the catheter shaft, which, in conjunction with a
distal balloon, allows for the deployment of contrast fluid distal
to the distal end of the catheter for visualizing the venous
structure.
[0007] The following U.S. Patents discuss related devices and
methods for their use: U.S. Pat. Nos. 5,509,411, 5,645,064,
5,682,885, 5,699,796, 5,706,809, and 5,711,298, each to Littmann et
al; U.S. Pat. Nos. 5,881,732 and 5,645,082, each to Sung et al;
U.S. Pat. No. 5,766,152 to Morely et al; U.S. Pat. Nos. 5,782,760
and 5,863,291, each to Schaer; U.S. Pat. No. 5,882,333 to Schaer et
al., and U.S. Pat. No. 6,122,552 to Tockman et al.
[0008] However, despite the advantages of these sensing devices and
guiding catheters, it remains quite difficult to accurately and
reliably contact the various curved shapes one encounters in the
endocardial lining. This is due to the frequent inability to
customize the shape of their distal portion, or at least the
inability to instantaneously and accurately adjust their shape upon
demand during deployment to conform to the shape of the tissue of
interest.
[0009] Concerns similar to those described above are associated
with the placement of leads within the heart and other areas of the
coronary vasculature. For example, pacemakers,
defibrillator/cardioverters, and other implantable medical device
(IMDs) may employ one or more electrodes that are maintained in
contact with a patient's heart muscle and through which electrical
stimulation of the heart muscle is achieved. Such devices typically
employ a flexible conductive lead that connects a remotely
positioned and implanted power source to the one or more
electrodes. Secure placement of the electrodes in the selected
heart chamber (typically the right atrium) or in a coronary vein or
artery is required to assure appropriate and reliable
depolarization or "capture" of cardiac tissue by electrical stimuli
delivered by the IMD.
[0010] Many problems exist with reliably and accurately placing
medical electrical leads and other similar devices such as
catheters within the heart and associated vasculature. For
instance, when placing transvenous leads or catheters, it is often
difficult to engage the coronary sinus and sub-select the proper
vessel into which the lead or catheter is to eventually be placed.
Moreover, once placed, transvenous devices suffer from a relatively
high rate of dislodgment from sites adjacent to, or on, the
epicardium. Such dislodgement may result in a loss of capture or,
at best, a reduction of the degree of electrical coupling between
the electrode and the myocardium. More accurate and secure
placement of the lead or catheter would not only reduce the
difficulty and time associated with lead placement, but would
reduce the risk of subsequent dislodgment as well.
[0011] There thus is a need for a method and system for placing
intralumenally-deployed devices such as electrophysiology catheters
and leads into selected areas of the coronary vasculature in a
highly accurate and reliable fashion.
SUMMARY OF THE INVENTION
[0012] The current invention provides an improved system and method
for placing implantable medical devices (IMDs) such as leads within
the coronary sinus and branch veins. In one embodiment, a slittable
delivery sheath is provided. The sheath includes a slittable hub,
and a substantially straight body defining an inner lumen. The body
comprises a shaft section and a distal section that is distal to,
and softer than, the shaft section. A slittable braid extends
adjacent to at least a portion of one of the shaft section and the
distal section. In one embodiment of the invention, the sheath
further includes a transition section that is distal to the shaft
section, and proximal to the distal section. The transition section
is softer than the shaft section, but stiffer than the distal
section.
[0013] In one embodiment of the invention, at least one of the
sections of the sheath includes multiple segments. In general, the
stiffness associated with the multiple segments within a section
decreases from the proximal to distal end of the section. For
example, in one embodiment, the shaft section includes proximal,
intermediate, and distal shaft segments, with the proximal shaft
segment being the hardest, the intermediate shaft segment being
more flexible, and the distal shaft section being the most flexible
within the shaft section. Similarly, the transition section may
include at least two segments, with the more proximal transition
segment being harder than the distal transition segment. Finally,
distal section includes a very soft atraumatic tip, and a soft
distal segment. A harder intermediate segment may be provided
between soft tip and soft distal segment to terminate the
braid.
[0014] In one embodiment, the inner lumen of the sheath is between
0.086 and 0.106 inches, and in a particular embodiment is
approximately 0.096 inches. The sheath may further include an
internal liner adjacent to at least a portion of the inner lumen.
This liner may be formed of a lubricious material such as PTFE to
allow leads and other devices to be more easily advanced within the
lumen.
[0015] The sheath of the current invention includes characteristics
that make it ideal for placing leads and other devices within the
coronary sinus or the branch veins thereof. For example, the
segments at the distal end of sheath are formed of a relatively
soft material, and therefore provide a very soft atraumatic tip
that minimizes the chance of tissue damage. Additionally, the braid
provides support to sheath shaft, making it more kink resistant as
it is pushed through the vascular system during an implant
procedure. Kink resistance is further enhanced by using the
transition section to provide gradual changes between the stiffer
shaft section and the soft distal section. As a result, the sheath
can survive a ninety-degree bend without kinking when supported by
another device such as a steerable EP catheter. These same
attributes provide for a sheath that is more pushable than prior
art designs, make it easier to navigate the torturous curves of the
venous system.
[0016] The foregoing attributes also provide a device that is
easier to remove from the body after a lead or other IMD has been
positioned at a final implant location. The soft distal section and
substantially straight profile of the sheath allow it to easily
track over another device such as a lead to prevent the "whipping"
effect that is commonly exhibited by prior art sheaths. This is
particularly important when the sheath is withdrawn from the
coronary sinus or branch vein, since a whipping motion can dislodge
the lead, making it necessary to repeat the entire procedure.
[0017] Additionally, the sheath of the current invention is
designed to be slittable. That is, the system uses braid materials
that are slittable, yet provide maximum backup support and
pushability to the sheath body. This allows the sheath to be slit
away from leads and other IMDs having larger connectors, including
IS-1 standard connectors. The selection of braid materials
maintains this slitting capability without sacrificing the
beneficial properties that make the sheath easier to navigate.
[0018] Finally, the sheath has an outer diameter that is small
enough to be advanced within the coronary sinus and into branch
veins. The very soft atraumatic tip allows this to be accomplished
without damaging tissue. Additionally, the lubricious internal PTFE
liner allows leads and other IMDs to be advanced within the sheath
internal lumen when only a minimal amount of clearance is
available.
[0019] According to yet another aspect of the invention, a system
for positioning implantable medical devices within the coronary
sinus or a branch vein is disclosed. The system includes an
inventive sheath similar to that set forth above. The sheath is
slittable, and has a substantially straight profile. The sheath
further includes a shaft section, and a distal section that is
distal to, and softer than, the shaft section. A slittable braid is
provided adjacent to at least a portion of at least one of the
shaft section and the distal section. The system further includes a
steerable catheter having a shaft adapted to be inserted within the
inner lumen of the sheath. The steerable catheter may be used to
navigate the sheath into the coronary sinus and/or a branch vein
thereof.
[0020] In still another embodiment of the invention, a method of
using the novel sheath for seating implantable medical devices such
as leads within the coronary sinus or branch veins is disclosed.
The method includes providing a slittable sheath having a
substantially straight body defining an inner lumen. The body of
the sheath comprises a shaft section and a distal section that is
distal to, and softer than, the shaft section. A slittable braid
extends adjacent to at least a portion of one of the shaft section
and the distal section. The method further includes inserting a
steerable catheter such as a steerable EP catheter within the inner
lumen of the sheath, positioning the steerable catheter and sheath
within a body, and navigating the steerable catheter and the sheath
into the coronary sinus of the body.
[0021] In one embodiment of the invention, the method further
includes advancing an implantable medical device (IMD) such as a
lead within the inner lumen of the sheath. The lead may be loaded
with a navigational device prior to advancing the lead within the
inner lumen of the sheath. Alternatively, a navigational device may
be advanced within the lumen of the sheath, and the lead may be
advanced over the navigational device. This navigational device may
be a stylet, a guidewire, a micro-deflection mechanism, or any
other navigational device known in the art. The lead and
navigational device may then be used to sub-select a branch vein of
the coronary sinus. In yet another embodiment, the sheath may
sub-select the branch vein prior to advancing the lead and
navigational device to a target destination.
[0022] Other scopes and aspects of the current invention will be
apparent from the following description and the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A is a side cutaway view of a delivery sheath of the
present invention.
[0024] FIG. 1B is a cross-sectional view of a delivery sheath of
the present invention.
[0025] FIG. 1C is a perspective view of an additional embodiment of
the sheath of the current invention.
[0026] FIG. 1D is a side cut-away view of the sheath shown in FIG.
1C.
[0027] FIG. 1E is a perspective cutaway view of the sheath of FIGS.
1C and 1D.
[0028] FIGS. 2A-2B are side and cross-sectional views,
respectively, of a balloon catheter as may be used with the sheath
of the present invention.
[0029] FIG. 3 is as side view illustrating components included in
both the deflection mechanism and micro-deflection mechanism as may
be used with the sheath of the present invention.
[0030] FIGS. 4A-4B are various views of a handle as may be used
with the deflection and micro-deflection mechanisms of FIG. 3.
[0031] FIG. 5 is a cross-sectional side view of a deflection
mechanism, an outer sheath, and a balloon catheter with an inflated
distal balloon and a deflected distal end.
[0032] FIGS. 6A-6D are various views of a micro-deflection
mechanism handle.
[0033] FIGS. 7A-7B are two embodiments of deflection and
micro-deflection mechanisms detailing two notch configurations.
[0034] FIGS. 8A-8D are additional embodiments of deflection and
micro-deflection mechanisms, detailing additional notch
configurations.
[0035] FIG. 8E is a cross-sectional view of a deflection and
micro-deflection mechanism having a tubular member with an
irregular wall thickness to provide a preferred bending
direction.
[0036] FIGS. 9-11 depict a method for accurately placing an
endocardial lead into the cardiac venous system through the
coronary sinus ostium using a system of the present invention.
[0037] FIG. 12 is a plan view of a steerable catheter that may be
used as an alternative deflection mechanism to navigate the balloon
catheter 200 into the coronary sinus.
[0038] FIGS. 13A through 13C are side views of steerable catheter
being deflected in various configurations.
DETAILED DESCRIPTION OF THE INVENTION
[0039] This invention involves a method and system for intralumenal
visualization and deployment of implantable medical devices (IMDs)
such as transvenous leads, electrophysiology catheters and the like
to various targeted regions of the body. The inventive system
includes a sheath, which may be used along with a balloon catheter
and associated deflection mechanism, and a micro-deflection device
for highly accurate placement of the lead, catheter, or other
device once the area of interest has been visualized.
[0040] The following description sets forth several embodiments of
the inventive sheath, followed by a description of additional
components that may be used with the sheath to place a transvenous
lead into the coronary veins. Although the description sets forth
several methods for using the sheath, as well as an exemplary set
of system components for use in conjunction with the current
invention, other system configurations, adaptations, and methods of
use are within the scope of the invention.
[0041] In general, the invention involves a sheath that is adapted
to be highly pushable, and yet having a soft enough distal tip to
track a lead body or the body of another implantable medical device
(IMD). The sheath may be positioned within a chamber of the heart
or within a coronary vein such as the coronary sinus using a
catheter such as a steerable electrophysiology (EP) catheter. The
sheath may then be used to deploy an intralumenal visualization
system and micro-deflection device that may include a deflectable
catheter having an inflatable member such as a balloon. The
inventive device may be inserted into the body via a typical
introducer as will be described in more detail.
[0042] In one use of the sheath, the sheath and a steerable
electrophysiology (EP) catheter are inserted together into the
body. The EP catheter is employed to navigate the sheath into the
coronary sinus. The EP catheter is withdrawn, and a balloon
catheter is inserted into the lumen of the sheath so that a
venogram may be obtained. The balloon catheter is withdrawn, a lead
is inserted through the sheath lumen and into the coronary sinus.
Using the venogram data, the lead may be advanced into a branch
vein of the coronary sinus.
[0043] Because the sheath of the current invention has a body with
a high degree of pushability and an extremely soft distal tip, it
may be guided into a branch vein to aid in placement of the lead,
if necessary. Once the lead is in position, the sheath may be
withdrawn from the body. This can be accomplished by pulling the
sheath in a proximal direction over the lead body and connector.
Since the sheath is substantially straight and possesses a very
flexible, soft distal tip, the sheath body tracks the lead as it is
withdrawn from the coronary sinus during this process. This
prevents a "whipping" effect that may cause lead dislodgment. The
current sheath is further designed to be slittable, so that it may
be removed from a lead having a standard, larger profile, connector
such as an IS-1 connector.
[0044] In another variation of the above-described process, a
balloon catheter is guided by a deflection mechanism to engage the
coronary sinus ostium, and an occlusive venogram is obtained. The
sheath of the current invention is then slid over the balloon
catheter into the coronary sinus, and the balloon catheter is
removed. A lead with a micro-deflection mechanism is inserted into
the sheath lumen and is deployed at a desired location in the
coronary veins. The micro-deflection mechanism disposed within the
lead is used to provide rigidity to the lead and to allow a means
to sub-select coronary vessels. As described above, the sheath may
be splittable along its longitudinal length so that it may be
removed around the lead without disturbing it. With the foregoing
system summary set forth as background information, a detailed
description of the inventive sheath follows.
Delivery Sheath
[0045] FIG. 1A is a cutaway side view depicting one embodiment of
the delivery sheath of the current invention. As best seen in FIG.
1A, sheath 100 comprises an elongate shaft 102 containing a central
lumen 104 throughout its length. The working length of sheath 100
comprises a distal end 112, a distal section 110, and a proximal
section 120, each of which comprises a polymeric jacket material
having differing flexibilities as described below.
[0046] Near the proximal end of sheath 100, a hub 114 may be
affixed to proximal section 120 by an adhesive or other suitable
means. An ultraviolet-curable adhesive sold by Loctite Corp. of
Rocky Hill, Connecticut under the name UV 4201 may be used for this
purpose. Alternatively, an adhesive sold by Dymax corp. of
Trorrington, Connecticut under the trademark DYMAX may be employed.
Hub 114 is made from any suitable medical-grade polymer, and is
preferably injection molded and longitudinally scored or perforated
so that it may be removed from around a device without disturbing
that device. It may be molded in situ onto the proximal section 120
of shaft 102.
[0047] In one embodiment, hub 114 has an opening large enough to
accommodate a special rotatable hemostatic valve (RHV) 118, which
seals a compressible annular ring on valve 118 inner diameter. A
central lumen 124 in RHV 118 is aligned and in fluid communication
with the lumen of shaft 102. Lumen 124 has a diameter large enough
to accommodate a balloon catheter and a typical lead connector,
such as an IS-1-type connector. An optional side arm (not shown)
may be disposed on RHV 118 in fluid communication with lumen 124.
RHV 118 may also be splittable via a scoring or perforation as
described above.
[0048] An annular polymeric collar 116 is disposed on the outside
diameter of RHV 118 distal portion proximal to the point where hub
114 meets RHV 118. In this embodiment, rotation of collar 116 locks
the RHV 118 to hub 114. Hub 114 may have a non-standard diameter so
that RHV 118 can be removed over an IS-1 lead connector prior to
slittably removing sheath 100 from the lead.
[0049] FIG. 1B is a cross-sectional view of the delivery sheath
embodiment of FIG. 1A. As shown in FIG. 1B, a cross-section of
shaft 102 in the distal section 110 reveals shaft lumen 104. The
inner diameter of shaft 102 will vary depending on the outer
diameter of the balloon catheter and the lead, each of which should
be capable of passing through lumen 104. Typically the shaft inner
diameter is between about 0.070 and 0.110 inches. In one
embodiment, the shaft inner diameter is between about 0.096 and
0.098 inches. Likewise, in one embodiment, the outer diameter of
shaft 102 is between about 0.090 and 0.140 inches, and may be
between 0.116 and 0.118 inches. It is desirable to make the outer
diameter of shaft 102 as small as possible while still maintaining
acceptable performance levels according to the application for
which the shaft is used. Additionally, it is desirable for shaft
102 to maintains a substantially constant inner diameter throughout
its length to provide a smooth and continuous step-free profile for
the passage of various devices and materials therethrough as
described herein.
[0050] Tubing comprising distal section 110 and proximal section
120 will typically be polymeric, and is preferably any typical
acute-use medical grade, biocompatible tubing with the appropriate
performance characteristics as described herein. An especially
desirable material is an extruded polyether block amide of the type
sold by Atochem North America, Inc., Philadelphia, Pa. under the
trademark PEBAX. In the current embodiment, distal and proximal
sections 110 and 120, respectively, are constructed of tubing
having a durometer hardness ranging from about 20D to 100D (shore).
The working length of shaft 102 preferably is composed of materials
having two or more stiffnesses, although shaft 102, having a single
stiffness value throughout its length is within the scope of the
invention. In the latter embodiment, Grilamid ELY 2702 from EMS
Chemie may be employed to form a single-stiffness shaft 102. In
either case, the shaft may have an inner diameter of about 0.098
inches, and an outer diameter of about 0.136 inches.
[0051] In one embodiment, proximal section 120 comprises a
relatively high stiffness material (typically about 72D) in
comparison to the more flexible distal section 110 (typically about
40D). Although not shown in the view of FIG. 1B, distal section 110
and proximal section 120 may be comprised of a DACRON polyester
(E.I. du Pont de Nemours and Company, Wilmington, Del.) braid with
a PolyTetraFluoroEthylene (PTFE) liner. It may be noted that
incorporation of this type of polyester braid within sheath 100
results in a structure that is less stiff than if a stainless steel
braid is used, as is described below in reference to another
embodiment of sheath 100. The braid may be surrounded by the PEBAX
tubing, which renders the proximal section 120 of shaft 102
generally stiffer and less flexible than distal portion 110.
[0052] Distal end 112 is preferably a soft, atraumatic tip made
from a relatively low stiffness polymeric material to prevent
injury to the intima of the vessel walls or to other tissue. One
material well suited for distal end 112 is a low-durometer
thermoplastic polyurethane elastomer such as PELLETHANE (Dow
Chemical Co., Midland, Mich.) or the like.
[0053] According to one aspect of the invention, distal portion 110
may be radiopaque. This can be achieved by the inclusion of
radiopaque metals or their alloys into the structure, or more
preferably by incorporating radiopaque filler materials such as
BaSO.sub.4, BiCO, etc. into the polymer comprising distal portion
110. Distal end 112 is preferably more radiopaque than distal
portion 110. This can be achieved by the incorporation of greater
quantities of radiopaque materials, for instance, into the tubing,
or by the use of a different material having greater radiopacity
than that used in distal portion 110. This radiopaque feature
allows the user to more readily visualize these portions of sheath
100 under fluoroscopy.
[0054] The entire length of shaft 102 (from distal end 112 to the
far proximal end of RHV 118) is typically between about 40 and 60
cm, and in the current embodiment is about 55 cm. Distal end 112
may be between about 0.2 cm and 0.5 cm long, while distal section
110 is generally between about 5 and 10 cm long, and is preferably
about 8 cm long. Proximal section 120 is between about 35 and 50 cm
long, and in the current embodiment is approximately 42 cm.
[0055] Both the working length of shaft 102 as well as the attached
hub 114 may contain a perforation or score 126 along their
longitudinal axes. Alternatively, they may be otherwise configured
to split so that they may be opened and removed from around an
inserted device such as a lead or electrophysiology catheter
without having to axially slide the sheath 100 relative to the
device. A special tool may be used to facilitate such splitting, or
the sheath/hub (and even RHV 118) combination may be split by hand
without the aid of any special device. The splittable valve and
sheath combinations as described in U.S. Pat. No. 5,312,355 to Lee
is exemplary.
[0056] In another embodiment, the materials included within sheath
100 may be selected so that the sheath is slittable. For example,
the braid materials included within sheath are of a thickness that
may be severed with currently-available slitting tools. A slitting
tool of the type that may be used to remove a sheath of this
embodiment is described in commonly-assigned U.S. patent
application Ser. No. 10/078,026 filed Feb. 15, 2002 entitled
"Slitting Tool". This is discussed further below in regards to the
following additional embodiment.
[0057] FIG. 1C is a perspective view of an additional embodiment of
the sheath of the current invention. At the proximal end, sheath
130 includes a hub 131 that is shown coupled to handle 132. Handle
132 may be integrally formed with hub, or may be coupled to hub by
any coupling mechanism known in the art. Hub is formed of a
material that is soft enough to be slittable using conventional
sitting tools of the type described in the above-referenced
application entitled "Slitting Tool". In one embodiment, hub 131 is
formed of PEBAX having a durometer hardness of 70D (Shore).
[0058] The body of sheath 130 includes multiple sections, each
having an outer polymer layer, which may be formed of PEBAX tubing.
The hardness of the polymer in each section generally decreases
from the proximal to the distal end of sheath 130. In this
embodiment, proximal end of sheath 130 includes a shaft section 133
that has a length ranging from about 43 to about 62 cm and a
hardness that may range from about 72D to 55D. Distal to shaft
section 133 is a transition section 134 having a length of between
approximately 2.25 and 5.5 cm, and having a hardness ranging from
approximately 35D to 40D. Finally, shaft includes a distal section
135 distal to transition section 134. Distal section 135 has a
length of approximately 1.5 to 3.5 cm, and a hardness that is less
than transition section 134, and which may range from 25D to
35D.
[0059] According to one embodiment of the current invention, shaft
section 133 may be sub-divided into segments. In FIG. 1C, shaft
section 133 includes three segments 136, 137, and 138 of varying
hardnesses. For example, proximal shaft segment 136 may have a
length that ranges from 40 to 55 cm, and a hardness that ranges
from 70D to 72D (Shore). In one particular embodiment, proximal
shaft segment 136 has a length of between 45 and 50 cm, and
hardness of approximately 72D.
[0060] In the current embodiment, shaft section 133 next includes
an intermediate shaft segment 137 having a length that ranges from
approximately 1.5 to 3.5 cm, and a hardness that ranges from 63D to
72D. The particular embodiment includes intermediate shaft segment
137 having a length of approximately 2.5 cm, and a hardness of
approximately 63D. Finally, distal shaft segment 138 has a length
of between approximately 1.5 to 3.5 cm, and a hardness that ranges
from 55D to 63D. The particular embodiment includes distal shaft
segment 138 that is between 2 and 3 cm, and preferably 2.5 cm, in
length, and which has a hardness of approximately 55D.
[0061] In a manner similar to that discussed above with respect to
shaft section 133, transition section 134 may be sub-divided into
segments. For example, FIG. 1C illustrates transition section 134
including proximal transition segment 140 and distal transition
segment 142. Proximal transition segment 140 has a length ranging
between approximately 1.5 to 3.5 cm, and a hardness that ranges
from 35D to 40D. In the particular embodiment, proximal transition
segment 140 is between 2 and 3 cm, and preferably 2.5 cm, long. In
this particular embodiment, proximal transition segment 140 has a
hardness of approximately 40D. Distal transition segment 142 has a
length ranging between 0.75 and 2.0 cm, and a hardness ranging
between 35D to 40D. In the particular embodiment, distal transition
segment 142 is between approximately 1 to 2 cm, and preferably
about 1.25 cm, in length. The hardness of distal transition segment
142 in the particular embodiment is approximately 35D.
[0062] In a manner similar to that described above with respect to
shaft section 133 and transition section 134, distal section 135
may include multiple segments (not shown in FIG. 1C). This is
discussed further below.
[0063] Each of sections 133, 134, and 135 of shaft may incorporate
radiopaque filler material such as BaSO.sub.4 into the polymer
jacket to make sheath 130 visible under a fluoroscope. In one
embodiment, the PEBAX of shaft section 133 is approximately 30%
BaSO.sub.4 by weight. Similarly, transition section 134 includes
between 30% and 40% BaSO.sub.4 by weight. In one embodiment,
proximal transition segment 140 is approximately 30%, and distal
transition segment 142 is about 40%, BaSO.sub.4 by weight. This
allows the distal tip section to be slightly more visible than the
more proximal section under flouroscope. Similarly, distal section
may be between approximately 30% and 40% BaSO.sub.4 by weight.
Distal section may further be loaded with tungsten carbide to make
it even more radiopaque.
[0064] In one embodiment, distal section includes a radiopaque
marker band. The radiopaque marker band may be formed by loading a
portion of the polymer jacket with an even higher percentage of a
radiopaque filler material, or by incorporating a filament of metal
having a high radio-density, such as gold or platinum, within the
distal section.
[0065] FIG. 1D is a side cut-away view of the sheath embodiment
shown in FIG. 1C. FIG. 1D includes shaft section 133, transition
section 134, and distal section 135. As noted above, shaft section
133 is divided into segments 136, 137, and 138, and transition
section 134 is divided in segments 140 and 142. Similarly, distal
section 135 may also be divided into portions shown as a soft
distal segment 144, an intermediate distal segment 146, and a soft
tip 148. Soft tip 148 is between 0.15 and 0.35 cm long, and in the
particular embodiment is approximately 0.25 cm long. Soft tip is
made of material that is very soft to prevent tissue damage. In one
embodiment, soft tip 148 is formed of PEBAX with a hardness ranging
from 25D to 35D, and is preferably 25D PEBAX. Soft tip 148 may
extend slightly beyond internal liner 150, as shown in FIG. 1D.
Additionally, soft tip 148 may be radiused such that the distal end
of sheath 130 has a rounded profile that will reduce chance of
tissue perforation.
[0066] For reasons discussed below, a harder intermediate distal
segment 146 may be provided just proximal to soft tip 148.
Intermediate distal segment 146 may have a length of between about
0.2 and 0.45 cm, and in the particular embodiment, is approximately
0.37 cm in length. This segment may be formed of PEBAX having a
hardness ranging from 35D to 72D, and is preferably 35 D PEBAX.
According to one aspect of the invention, intermediate distal
segment 146 comprises a radiopaque marker band that is visible
under a fluoroscope. This radiopaque marker band may take the form
of any of the embodiments discussed above.
[0067] Finally, soft distal segment 144 is formed of a material
having a hardness that is similar to that used to form soft tip
148. Soft distal segment 144 may be between about 1 and 3 cm, and
in the particular embodiment is approximately 1.9 CM.
[0068] The current embodiment of sheath 130 has an internal lumen
152 having an inner diameter that may range from approximately
0.086 to 0.106 inches, and in a particular embodiment, has an inner
diameter of about 0.096 inches. The surface of lumen 152 is
provided by an internal liner 150 extending along at least part of
the length of lumen 152. This liner may be formed of a lubricious
material such as PTFE, PolyVinylDieneFluoride (PVDF), or
High-Density PolyEthylene (HDPE) to allow IMDs such as leads to be
easily slid within the lumen. In an embodiment that does not
include liner 150, the surface of lumen 152 may be coated with a
hydrophilac material to make that surface more lubricious.
[0069] Sheath 130 of the current embodiment may further include a
braided reinforcement such as braid 154 extending along at least a
portion of at least one of the sections of sheath 130. This braid
may be constructed of any biocompatible metal such as stainless
steel. In the current embodiment, braid 154 is formed of 0.002-inch
type-304 vacuum melt stainless steel wire. The wire may have a
nominal Ultimate Tensile Strength (UTS) of between 200-250
kilo-pounds per square inch (ksi), and in the particular embodiment
has a UTS of 220 ksi. The braid may include a continuous braid
pattern such as eight wires by eight wires. In this particular
embodiment, the braid configuration is further defined as having
between 35 and 55 pic crossings (pics) per inch.
[0070] Braid 154 may optionally be terminated at its distal end
using a heat shrink tube such polyester tubing. Alternately, the
strands of the braid may be glued in place using a medical grade
adhesive such as cyanoacrylate. In the embodiment shown in FIG. 1D,
intermediate distal segment 146 is formed of a harder material that
then surrounding segments, soft tip 148 and soft distal segment
144. The use of a harder material maintains the strands of the
braids in position so that these strands do not migrate to the
outer surface of sheath distal tip. In one embodiment, braid 154 is
terminated approximately at the transition 160 between soft tip 148
and intermediate distal segment 146. For example, the distal end of
braid, in one embodiment, ends in a region that is within
approximately 0.07 cm from transition 160 in soft distal segment
144, or is within approximately 0.3 cm from transition in
intermediate distal segment 146.
[0071] FIG. 1E is a perspective cutaway view of the sheath of FIGS.
1C and 1D. This view shows internal liner 152, braid 154, and a
portion of sheath that, for exemplary purposes, is shown as shaft
section 133. However, a similar view applies to intermediate and
distal sections, 134 and 135, respectively. This figure illustrates
the eight-by-eight continuous braid pattern discussed above.
According to one embodiment of the invention, several strands of
braid 162 are formed of metals that are more radio-dense than the
others, and are therefore more visible under fluoroscopy. These
strands provide a profile of sheath when viewed under a
fluoroscope.
[0072] Sheath 130 of the current embodiment includes
characteristics that make it ideal for placing leads and other IMDs
within the coronary sinus or branch veins. For example, the
segments at the distal end of sheath 130 are formed of a relatively
soft material. This provides a very soft atraumatic tip that
minimizes the chance of tissue damage. Additionally, the braid
provides support to sheath shaft, making it more kink resistant as
it is pushed through the vascular system during an implant
procedure. Kink resistance is further enhanced by using transition
section 134 to provide gradual changes between the stiffer shaft
section 133 and soft distal section 135. As a result, sheath 130
can survive a ninety-degree bend without kinking when supported by
a steerable EP catheter in the manner discussed in detail below.
These same attributes provide for a sheath that is more pushable
than prior art designs, make it easier to navigate the torturous
curves of the venous system.
[0073] The foregoing attributes also provide a device that is
easier to remove from the body after a lead or other IMD has been
positioned at a final implant location. The soft distal section 135
and substantially straight profile of sheath 130 allow it to easily
track over another device such as a lead to prevent the "whipping"
effect that is commonly exhibited by prior art sheaths. This is
particularly important when the sheath is withdrawn from the
coronary sinus or branch vein, since a whipping motion can dislodge
the lead, making it necessary to repeat the entire procedure.
[0074] Additionally, the sheath of the current invention is
designed to be slittable. That is, the system uses braid materials
that are slittable, yet provide maximum backup support and
pushability to the sheath body. This allows sheath 130 to be slit
away from leads and other IMDs having larger connectors, including
IS-1 standard connectors. The selection of braid materials
maintains this slitting capability without sacrificing the
beneficial properties that make the sheath easier to navigate.
[0075] Finally, sheath 130 has an outer diameter that is small
enough to be advanced within the coronary sinus and into branch
veins. The very soft atraumatic tip allows this to be accomplished
without damaging tissue. Additionally, the lubricious internal PTFE
liner allows leads and other IMDs to be advanced within the sheath
internal lumen when only a minimal amount of clearance is
available.
[0076] The inventive sheath described above may be used in
combination with the components, including a balloon catheter, a
deflection mechanism, and/or a micro-deflection mechanism described
below to facilitate placement of leads and other devices within the
coronary sinus and branch veins. Various exemplary methods of using
the sheath are further discussed below.
Balloon Catheter
[0077] Turning now to FIGS. 2A-2B, an exemplary balloon catheter
200 as may be used within the sheath of the present invention is
shown in side view and distal cross-sectional view, respectively.
This catheter is largely similar to the guiding catheters disclosed
in U.S. Pat. Nos. 6,021,340 and 5,775,327 to Randolph et al, the
entirety of each of which are incorporated herein by reference, as
well as the VUEPORT family of balloon occlusion guiding catheters
sold by Cardima, Inc. of Fremont Ca.
[0078] Catheter 200 is designed to pass through the central lumen
104 of the delivery sheath discussed above, and reach the
therapeutic site as a combined unit with sheath and deflection
mechanism 300.
[0079] As shown in FIGS. 2A and 2B, balloon catheter 200 generally
includes an elongated shaft 202, a distal shaft section 204, a
proximal shaft section 206, and an inner lumen 208. A female luer
lock 210 may be disposed on the proximal end of shaft 202 and
secured by a suitable adhesive 212, such as UV-curable Loctite
4201.
[0080] A distal port 214 is provided in the distal end 216 of the
catheter shaft that is in fluid communication with the inner lumen
208. Proximal of distal end 216 is an occlusion balloon 211 axially
disposed in the distal section 204 about catheter shaft 202. The
catheter shaft 202 is provided with an inflation lumen 209 that
extends through the shaft 202 to the interior of the balloon 211 to
direct inflation fluid therein.
[0081] On the proximal end of catheter 200, proximal to luer lock
210, is a multiarm adapter or hub 222 that terminates in a
Y-adapter or hemostasis valve 232 and a proximal port 218 for
passage of a deflection mechanism therethrough as described
later.
[0082] A first sidearm or port 224 on adapter 222 (shown in partial
cross section in FIG. 2A) facilitates introduction of inflation
fluid into inflation lumen 209. A stopcock 228 on first sidearm 224
that allows balloon 221 to stay inflated once the proper volume of
fluid (such as air) has been introduced via syringe 230 is disposed
adjacent stopcock 228. Inflation lumen 209 is disposed in port 224
and extends distally into shaft 224 to facilitate inflation of
balloon 211 as described above.
[0083] A second sidearm or port 226 may also be disposed on hub
222, and may be in direct fluid communication with large inner
lumen 208. Inner lumen 208 is used for housing devices such as a
deflection mechanism or the like. Once balloon 211 is inflated, the
second port 226 may be used for introducing contrast media or
similar material through lumen 208 and out the distal port 214 for
visualization of a section of interest in the body, such as an
organ lumen or the cardiac venous system, for instance.
[0084] Not shown is a rotatable hemostatic valve (RHV) that may be
housed in the proximal center port 218 and that can accept devices
such as a deflection mechanism described below. This RHV is capable
of sealing onto the deflection mechanism to prevent fluid leakage
and may be part of a duostat modified to comprise a single RHV and
two sideports. Other configurations, of course, are possible.
[0085] Shaft 202 of balloon catheter 200 is of a sufficient size so
that it may readily pass through the lumen 104 of sheath 100.
Ideally, we prefer the outer diameter of shaft 202 to be between
approximately 0.050 inch and 0.100 inch. More preferably, it is
between 0.060 inch and 0.080 inch, and most preferably is about
0.074 inch.
[0086] The diameter of inner lumen 208 preferably is large enough
to allow free passage of contrast media or other material
therethrough so that venograms and similar diagnostic procedures
may be readily accomplished. It should also be large enough for the
passage of a deflection mechanism as discussed below in greater
detail. Finally, lumen 208 should allow the free passage of
contrast media or other agents therethrough while occupied by a
device such as a deflection mechanism. In general, we prefer that
inner lumen have a diameter of between 0.030 inch and 0.080 inches,
and is preferably about 0.048 inch. Likewise, inflation lumen 209
preferably has a diameter of between about 0.005 inch and 0.020
inch, and preferably is about 0.014 inch.
[0087] The balloon catheter shaft 202 preferably comprises PEBAX
tubing having a durometer hardness of between about 60D and 80D,
preferably about 72D. Preferably, shaft proximal section 206 has a
heat shrink tubing disposed on the outer surface thereof.
Preferably, this heat shrink tubing is polymeric and is comprised
of clear polyolefin or the like. Distal tip 216 is preferably a
soft, atraumatic tip made of a relatively flexible polymeric
material similar in composition and stiffness to distal tip 112 of
sheath 100. In one embodiment, distal tip is radiopaque.
[0088] The working length of balloon catheter shaft 202, which
includes the distal tip 216, distal section 204, and proximal
section 206, should be between about 50 cm and 90 cm, although it
may be longer or shorter depending upon the application. We
especially prefer a working length of approximately 70 cm, which
can accommodate a distal tip 216 of approximately 0.5 cm, a distal
section 204 of approximately 6 cm, and a proximal section 206 of
approximately 63.5 cm.
[0089] The length of the entire catheter 200 in this embodiment
(the working length of shaft 202 and the components disposed
proximal of proximal section 206 discussed above) should be about
77.5 cm. In general, we prefer that the balloon catheter shaft 202
be between about 15 cm and 20 cm longer than the above-described
sheath of the current invention.
[0090] Of course, the absolute and relative lengths of each
component of catheter 200 may vary considerably. The particular
application in which catheter 200 and the entire system of the
present invention is to be used will dictate the particular
dimensions and materials for it's various components (as well as
each of the components of the inventive system) described
herein.
[0091] Occlusion balloon 211, when inflated, should have a diameter
sufficient to seal the coronary sinus ostium. This inflated
diameter will typically be between about 0.2 inch and 1.0 inches,
and more preferably, between about 0.4 inch and 0.8 inches. We
prefer balloon 211 to comprise an inelastic or elastic polymeric
material. Polyurethane such as PELLETHANE 80A (Shore) is especially
preferable. The inner diameter of the uninflated balloon 211
typically will be between about 0.04 inch and 0.08 inches, and more
preferably between about 0.056 inch and 0.070 inches. The balloon
wall thickness typically will be between about 0.002 inch and 0.006
inches, and more preferably about 0.004 inches. Finally, the
balloon 211 length typically will be between about 6 mm and 14 mm,
and more preferably between about 8 mm and 12 mm.
Deflection Mechanisms and Micro-Deflection Mechanism
[0092] The deflection mechanism and the micro-deflection mechanism
are two separate components that may be used in conjunction with
the sheath of the present invention. Deflection mechanism 300 is
designed for use in the balloon catheter 200, and is similar in
many respects to the micro-deflection mechanism 400, only larger.
Micro-deflection mechanism 400 is designed for use in a variety of
applications where precise control and deflection of a device such
as a lead, electrophysiology catheter, or other similar IMDs, is
needed. Its small size relative to deflection mechanism 300 renders
it useful in a wide range of applications in which its small size
and flexibility may be relied upon.
[0093] FIG. 3 is a plan view illustrating components of both the
deflection and micro-deflection mechanisms, although it will be
described in terms of the deflection mechanism 300 for discussion
purposes. Deflection mechanism 300 generally comprises a proximal
section 304, a distal section 306, and a distal tip 308. Adjacent
the proximal section 304 is handle 310, a preferred variation of
which is shown in detail in FIGS. 4A and 4B.
[0094] Deflection mechanism 300 is designed to be placed through
proximal port 218 of the balloon catheter 200 and into the inner
lumen 208 such that the deflection mechanism distal tip 308
generally reaches distal section 204, and preferably distal tip
216, of balloon catheter shaft 202. When the handle 310 is
activated, the distal section 306 of deflection mechanism 300
deflects in a predetermined fashion, thus deflecting the distal
section 204 of the balloon catheter in a similar fashion. In this
way, balloon catheter 200 (or any device into which deflection
mechanism 300 is disposed) may be torqued to conform to the
particular lumen or cavity into which it is disposed.
[0095] Shaft 302 of deflection mechanism 300 comprises a tubular
member such as hypotube 312, preferably made of metallic
biocompatible material such as medical grade stainless steel,
titanium, nitinol, alloys of these, or any suitable material as
known to those of skill in the art. Hypotube 312 preferably has an
outside diameter small enough to fit within inner lumen 208 of
catheter 200 and is preferably less than 0.048 inch. As shown in
FIG. 3, hypotube 312 is beveled to form a strain relief 316 at the
distal end of hypotube 312. Of course, this particular
configuration of hypotube 312, as well as other aspects of the FIG.
3 deflection mechanism 300, is merely exemplary. Other
configurations that serve the purposes of this invention are within
the scope of this disclosure as well.
[0096] Disposed within a central lumen of hypotube 312 is a pull
wire 320, which can be a stainless steel, titanium, nitinol or
other metal or alloy or even polymeric wire which when pulled
activates the deflection of distal section 306 of deflection
mechanism 300. Pull wire 320 is attached to a flat spring 322,
which is disposed in the distal section 306 of deflection mechanism
300. Spring 322 is attached to hypotube 312 using any suitable
attachment method, such as welding, brazing, soldering, adhesives,
or the like as is known to those of skill in the art. Spring 322
may be brazed to hypotube 312 along braze zone 314 as seen in FIG.
3. Likewise, any similar suitable attachment techniques may be used
to attach pull wire 320 to spring 322. In one embodiment, the pull
wire and spring are brazed to one another in braze zone 318 as seen
in FIG. 3.
[0097] Distal deflection region 306 is preferably covered with
compliant polymeric medical grade tubing, such as polyester, PEBAX,
and tetrafluoroethylene. Especially preferred is a polymer of
tetrafluoroethylene hexafluoropropylene and vinylidene fluoride
known by its acronym as THV. This prevents fluid intrusion into the
deflection mechanism.
[0098] In an especially useful variation of the invention in which
the system is used for implanting a lead, the balloon deflection
mechanism 300 will be of sufficient diameter to provide rigidity to
the balloon catheter 200 during introduction into the coronary
sinus ostium. The curve reach and deflection range should be
sufficient to provide easy introduction into the coronary sinus
ostium, and the entire assembly should provide adequate pull
strength to deflect and torque the distal portion 204 of balloon
catheter shaft 202 during manipulation into the coronary sinus
ostium.
[0099] Turning now to FIGS. 4A-4B, a useful variation of handle 310
for manipulating deflection mechanism 300 is shown. Handle 310
includes body 324 and activation mechanism 326. Activation
mechanism 326 may be manipulated by pushing distally or pulling
proximally along a longitudinal axis of handle 310. The machined
parts of these components may be polymeric. For example, a
thermoplastic such as the acetyl homopolymer DELRIN (E.I. du Pont
de Nemours and Company, Wilmington, Del.) may be used for this
purpose. The molded parts may be formed of polymeric materials such
as ABS (acrylonitrile butadiene styrene) or the like. A proximal
end of pull wire 320 is disposed in a central lumen 328 of handle
310 and affixed into handle by means known to those of skill in the
art.
[0100] Handle 310 is preferably lightweight and ergonomically
configured for simple, one-handed operation. The deflection range
(the maximum angular displacement the distal tip 308 undergoes when
displaced from a straight and undeflected zero-degree position) may
be between about 90 degrees and 180 degrees, preferably between
about 100 degrees and 135 degrees. Further details of the features
and versatility of distal section 306 will be described in greater
detail below, as well a detailed description of how deflection is
achieved.
[0101] FIG. 5 depicts in partial cross-section three components
that may be used with the inventive sheath. Deflection mechanism
300 with handle 310 is shown disposed in the inner lumen of balloon
catheter shaft 202 via the proximal port 218 as previously
described. In turn, the combination deflection mechanism 300 and
balloon catheter 200 are disposed in the lumen 104 of sheath 100
(FIG. 1A and 1B). I may be noted that any embodiment of the sheath,
including that shown in FIGS. 1C and 1D, may be used in this
manner. In FIG. 5, the distal section of balloon catheter shaft 202
is shown in a deflected state via the action of the hypotube/pull
wire mechanism. Notice also that distal balloon 211 is inflated
with fluid provided through balloon fluid port 224. An RHV 118 for
outer peel-away sheath 100 as discussed herein is seen as a flush
port 129 disposed on RHV 118. For purpose of clarity, sheath hub
114 is not shown.
[0102] In general, there is no limit to the size of the deflection
mechanisms described herein. All of the related components are
readily scalable to larger or smaller sizes than those disclosed
here as would be apparent to one of ordinary skill in the art and
as the particular application demands.
[0103] Turning now to a more specific discussion of
micro-deflection mechanism 400 depicted generally in FIG. 3, the
features of this element are largely similar to those of deflection
mechanism 300. The features are generally smaller so that they may
be used within devices such as leads, electrophysiology catheters,
and the like as will be described below.
[0104] The micro-deflection mechanism utilizes a hypotube
configuration as shown in FIGS. 7A, 7B, and 8A through 8E. We
prefer the outer diameter of the micro-deflection mechanism
hypotube (not shown) to be between about 0.012 inch and 0.030 inch;
preferably between about 0.014 inch and 0.026 inch; most preferably
about 0.015 inch. This will allow introduction of the hypotube into
a conventional IS-1 lead connector, as well as allow for movement
of the hypotube within the entire length of the central lumen of a
lead body without causing any undue stress or damage to any of the
lead or catheter components.
[0105] We also prefer that the micro-deflection mechanism 400 pull
wire, which is also preferably stainless steel or nitinol, have an
outer diameter of between 0.005 and 0.015 inches, and more
preferably between about 0.006 and 0.010 inches. Most preferably,
the outer diameter is about 0.008 inch.
[0106] During deflection, we prefer that the distal-most 10 mm to
30 mm of the assembly 400 deflect, which in a preferred
application, will allow the lead into which assembly 400 is placed
to engage the coronary sinus ostium. Due to the smaller size and
greater maneuverability, assembly 400 may deflect through angles as
high 360 degrees and even 450 degrees or more. Such a high angular
deflection capability allows the mechanism 400 (and the device into
which it may be deployed) to create a tight loop. These high-angle
deflections are especially useful in electrophysiology applications
in which the micro-deflection mechanism 400 may be deployed in a
mapping/ablation microcatheter to effect circumferential ablation
patterns and the like in areas such as the cardiac pulmonary vein.
FIGS. 6A-6D depict various components of an especially useful
variation of micro-deflection mechanism 400 handle 414. As shown in
FIG. 6A, handle 414 includes a body 416 and an activation mechanism
418 that may be manipulated by pushing distally or pulling
proximally axially along a longitudinal axis of handle 310. The
handle has a relatively small length that may be in the range of
about 2 inches. This scales well with the other, smaller components
of micro-deflection mechanism 400, and also allows for simple,
one-hand fingertip operation by a physician. Of course, the sizes
may be sized as needed in a manner discussed above.
[0107] Micro-deflection mechanism 400 can be used to replace the
fixed-curve stylet generally used to provide a deflectable lead or
catheter. This deflectable lead or catheter may be more precisely
placed in the targeted region of the cardiac venous system,
overcoming the problems of state-of-the-art systems. In addition,
the micro-deflection mechanism may be used in conjunction with the
inventive sheath described above and other components discussed
herein for deflectable electrophysiological catheters.
[0108] Turning now to features that are common to both the
deflection mechanism 300 and micro-deflection mechanism 400
(hereinafter referred to in this generic discussion as simply
"deflection mechanism"), each operates on the same principal based
on a hypotube/pull wire assembly. The pull wire runs through the
middle of the hypotube and is attached, via brazing or the like, at
the distal end of the deflection mechanism.
[0109] The hypotube is allowed to deflect in a predetermined
pattern by a series of slots, or perfs, cut into the hypotube
distal section. U.S. Pat. No. 5,507,725 to Savage et al, U.S. Pat
Nos. 5,921,924 and 5,441,483 both to Avitall, U.S. Pat. No.
5,868,768 to Wickerski, U.S. Pat. No. 5,304,131 to Paskar, the
entirety of each which are hereby incorporated by reference,
describe various medical devices in which some type of notch is
used to effect deflection
[0110] FIGS. 7 and 8 depict two variations of notch patterns that
are useful in the present invention. Because of the scalability of
these features, they are useful in both the deflection assembly 300
as well as micro-deflection assembly 400.
[0111] In reference to FIGS. 7 and 8, and the following discussion,
note that due to the drawing space constraints, the "proximal
section" of the hypotube refers to a portion of the deflection
mechanism that is proximal only in that it is disposed proximal to
the corresponding distal section. It is possible that a
considerable length of the hypotubes depicted in FIGS. 7 and 8
exists proximal to the so-marked "proximal section".
[0112] In FIGS. 7A and 7B, two hypotube/pull wire combinations are
shown in top and side views, starting from the top of the page,
respectively. FIG. 7A depicts an assembly 700 in which a pull wire
704 is brazed, soldered, or otherwise affixed to the distal end of
hypotube 702 at hypotube distal section 708. Note that pull wire
704 is deployed inside hypotube 702. The pull wire is disposed in
the interior of hypotube 702 all the way to the hypotube distal
section 708 where it is affixed to hypotube 702 as described above.
In general, pull wire 704 is affixed in handle 310 such that when
the handle is activated, hypotube distal section 708 will deflect
on the same side on which notches 710 (or as discussed below, the
reduced wall thickness of hypotube) are located.
[0113] Each notch or pert 710 is progressively deeper as one moves
from the proximal end 706 of hypotube 702 to the distal end 708.
This particular feature will cause the hypotube to deflect in a
smooth consistent curve. Note that the spacing between notches 710
is constant, and the only dimension of each notch 710 that changes
its depth. The width remains constant. Each of these parameters may
vary as performance requires.
[0114] Further, the centroids of each notch are aligned along a
single, straight liner longitudinal axis as one moves from proximal
section 706 to distal section 708. This axis along which the
notches are aligned may be nonlinear. For instance, the axis may be
sinusoidal to provide a serpentine deflection profile, with a
constant or varying pitch, or the axis may have some other
curvilinear or even stepwise shape. Regardless of whether the notch
centroids are aligned along a linear or nonlinear axis, the
centroid of each notch does not have to line up along such an
axis.
[0115] Note also that the distance between adjacent notches as one
moves from one end of a notch to the other end of hypotube of FIG.
7A remains constant. That is, the longitudinal axes of the notches
are parallel to one another. This aspect of the notches or perfs
may also change depending upon the application.
[0116] Another variable that may affect the shape and performance
characteristics of the assembly 700 is the depth to which the
notches 710 are cut into the hypotube. For instance, in the
assemblies of FIGS. 7A and 7B, the notches are cut completely
through the wall thickness of hypotube 702. This need not be the
case. It is within the scope of the invention to provide notches in
hypotube 702 in which a discrete amount of material is removed from
the hypotube without penetrating through the hypotube thickness. A
wide variety of depth profiles and patterns in etching each notch
are therefore envisioned.
[0117] Taking this concept one step further, hypotube 702 need not
contain a series of notches or perfs to achieve the desired
preferential distance deflection shape and response. For instance,
it is within the scope of the invention to preferentially machine
or etch the bulk of hypotube 702 in an asymmetric fashion so that
when the pull wire 704 is activated, the distal section 708 of
hypotube 702 deflects in a predetermined pattern. In other words,
the wall thickness of hypotube 702 can be made to vary a function
of length and/or circumferential position in patterns ranging from
a simple tapering pattern to complex patterns in which
correspondingly intricate and complex deflection shapes and
resources may be had. Such a concept can be used alone or in
conjunction with the use of notches or perfs as described
herein.
[0118] Each of the parameters described above, as well as other
parameters such as hypotube wall thickness, material selection,
etc. may be chosen to effect a particular deflection pattern and
response depending upon the application for which the hypotube/pull
wire assembly (such as assembly 700) is intended. Furthermore,
variations in many of these parameters from notch-to-notch may also
be made. For instance, one notch may have a rectangular profile,
while another notch on the same hypotube may have a circular
profile, etc.
[0119] Software may be utilized to aid the designer, by way of
mathematical algorithms and the like, to ascertain the optimal
profile for hypotube 702 given a desired deflection shape, etc. For
instance, a designer may be able to choose the application for
which the assembly is to be used, and the software may select a
number of alternative shapes from which the designer may choose.
Once a deflection shape is chosen, the software will then calculate
the optimal hypotube profile.
[0120] FIG. 7B shows an assembly 750 in which hypotube 752 and pull
wire 754 are arranged in a similar fashion to those described above
and shown in FIG. 7A. The only difference in the assembly of FIG.
7B is that the constant spacing between the notches 756 is larger
than that in the assembly of FIG. 7A. This increased but constant
spacing between notches 756 results in hypotube 752 being slightly
heavier, since less material has been cut away from the hypotube.
When assembly 750 is deflected, this means that distal section 760
will deflect through a smaller angle with a larger curve diameter
(although the deflection shape will generally be similar as that of
the deflected assembly 700 due to the similar size, shape, and
orientation of the notches in each assembly) than that experienced
by assembly 700 in FIG. 7A for a given deflection force.
[0121] Turning now to FIGS. 8A through 8E, additional variations of
a notch pattern are shown (the pull wire is omitted for clarity).
In FIG. 8A, hypotube 810 with proximal section 812 and distal
section 814 contains a series of linear notches 816 similar to
those of FIGS. 7A and 7B, except that each end of notches 816
contain a secondary notch 818 oriented generally perpendicular to
notch 816. This notch design causes the distal section 814 of
hypotube 810 to deflect in a similar fashion as described above,
possibly with a tighter curve diameter.
[0122] The hypotube of FIG. 8B is identical to that of FIG. 8A,
except that the notch pattern begins closer to the proximal section
822 of hypotube 820. A longer length of hypotube distal section 824
will therefore deflect when activated by the pull wire.
[0123] FIG. 8C is a plan view depicting an embodiment of deflection
mechanism wherein the notches are arranged in a non-linear manner.
For example, a sinusoidal pattern is depicted, although many other
types of patterns are possible.
[0124] FIG. 8D is a plan view depicting an embodiment of deflection
mechanism wherein the notches are of different shapes and sizes.
For example, the notches may be circular, triangular, rectangular,
or any other pattern desired to allow the deflection mechanism to
assume a desired shape when tension is applied to the pull wire.
The notches may all have a uniform shape and size, or
alternatively, may have different shapes and/or sizes.
[0125] FIG. 8E is a cross-sectional view depicting an embodiment of
the deflection member wherein the hypotube has walls that are not
of a consistent thickness. The thinner region of the wall defines a
preferred bending direction when tension is applied to the pull
wire. In one embodiment, both a thinner wall thickness and the
creation of notches in the thinner region may be used to provide
the deflection mechanism in the hypotube or other tubular
member.
[0126] The notches or perfs described herein and shown in the
figures, as well as the varying wall thickness of the hypotube, may
be created by any means know to those of skill in the art. They may
be machines by traditional, laser, electron-discharge, or similar
machining methods, they may be chemically etched, etched using
known photolithographic techniques, etc.
[0127] A particularly useful feature in the deflection mechanisms
described herein is the active control feature of the deflection
mechanism handle (both handle 310 as well as handle 414). Once the
handle activation mechanism is engaged to deflect the distal
section as described above, the deflection can be reversed only by
the positive input of a user to disengage the same activation
mechanism. In one embodiment of the deflection mechanism described
above and shown in FIGS. 4A-4B and FIGS. 6A-6D, release of the
activation mechanisms 326 and 418 after these mechanism are
deployed results in the distal section remaining in a deflected
position. Reversal of this deflection requires that the
physician-user retract the activation mechanism, whereupon the
distal section 306 will resume the undeflected state until the
handle is activated once again. This feature allows the
physician-user to manipulate other portions of the inventive system
or to perform other tasks while the distal section 204 of balloon
catheter 200, for example, remains in the intended deflected or
undeflected state. Of course, it is within the scope of the
invention to design the handle so that activation to deflect distal
section is automatically reversed to return the distal portion to a
default undeflected state. This may be accomplished by a bias
spring or equivalent mechanism that activates when the physician
releases the positive input causing the initial deflection. Such a
design may also bias the distal end of the deflection mechanism to
automatically reverse to a default deflected position.
[0128] Another feature common to both handles 310 and 414 is the
presence of one or more limit stops that may be built into the
handle. These limit stops are designed to prevent over-deflection
of the deflection mechanism.
Deployment of Cardiac Lead
[0129] Turning now to FIGS. 9-11, a particularly useful application
for the system herein described is shown and is discussed below. In
particular, a method for intravascularly deploying the system into
the coronary sinus, obtaining an occlusive venogram, and accurately
subselecting a venous branch and placing a cardiac lead therein is
described.
[0130] To prepare for the procedure, balloon catheter 200 is
inserted within the lumen 104 of outer sheath to create a
sheath/catheter combination. A deflection mechanism 300 is advanced
into the large lumen 208 of the balloon catheter via proximal port
218 so that the distal tip 308 of the deflection mechanism shaft
308 is generally disposed in balloon catheter shaft 202 near shaft
distal tip 216 as previously describe. This creates a combination
sheath/catheter/deflection mechanism system as shown in FIG. 5.
Typically, a portion of shaft 202 will extend out through and
beyond the lumen 104 at the sheath 100 distal end 112 for some
length.
[0131] This three-component system is introduced into the patient's
venous system through the cephalic, subclavian or femoral vein via
a conventional introducer as known to those of skill in the art.
The physician uses the introducer to dilate the selected vein and
then advances the system through the introducer into the selected
vein.
[0132] Typically under fluoroscopic guidance, the physician
navigates the three-component system through the vasculature to and
through the superior vena cava 910 or inferior vena cava 940 (see
FIG. 9) and into right atrium 920 of the heart.
[0133] At this point, distal tip 216 of shaft 202 and distal
balloon 211 engage the coronary sinus ostium. The deflection
mechanism is used to help steer the shaft 202 distal tip 216 into
place. Balloon 211 is then inflated, and contrast is injected into
the coronary veins through the distal port 214 of shaft 202. This
creates an occlusive venogram for visualizing the coronary veins in
advance of placing the lead in the desired location.
[0134] Next, while balloon 211 is still in the coronary sinus, the
sheath 100 is advanced into the coronary sinus over the catheter
shaft 202 so that it may be available as a conduit for lead
placement. Once the sheath 100 is in place, the balloon 211 is
deflated and the balloon catheter 200 and the associated deflection
mechanism 300 are proximally withdrawn from sheath 100, leaving
sheath 100 alone in place in the coronary sinus as shown in FIG.
10.
[0135] Next, the micro-deflection mechanism 400 is placed into a
central lumen of a lead 600 so that the deflectable distal section
of micro-deflection mechanism 400 generally engages the distal
section of the lead 600. The combination of these components is
then advanced into the lumen 104 of sheath 100 and into the
coronary sinus ostium as seen in FIG. 11. From here, the physician
will activate the deflection mechanism to steer the
lead/micro-deflection mechanism combination. In one embodiment, the
micro-deflection mechanism may be used to subselect a venous branch
into which the lead is to be permanently placed. Of course, the
particular deflection shape and characteristics of micro-deflection
mechanism have been selected by the physician for optimal use in
navigating the venous system and creating the shape for the lead to
assume during lead placement.
[0136] Once the lead 600 is placed and the pacing thresholds are
acceptable, the RHV 118 is removed from the sheath and slid over
the lead connector (alternatively, RHV 118 may be split). Next,
preferably with the aid of a special slitting tool such as a
customized razor blade attached to the sheath 100, the sheath 100
and hub 114 are split along score 126 as the sheath is pulled away
from the lead 600 and removed from the body.
[0137] Micro-deflection mechanism 400 may be withdrawn from the
lead 600, after which the lead 600 is the only component left in
the body. Lead 600 remains in place, and may be coupled to a pulse
generator, cardioverter/defibrillator, drug delivery device, or
another type of IMD.
[0138] As discussed throughout the specification, the method
outlined above is merely exemplary of one way to deploy a cardiac
lead according to the present invention. For example, any
embodiment of the inventive sheath may be employed in the
above-described method, including sheath 130 (FIGS. 1C and 1D).
Many alternative applications for the invention are likewise
possible. Significant variations from this technique may occur
within the scope of the present invention.
[0139] For example, in one embodiment, the deflection mechanism
that is adapted to be inserted within the balloon catheter is a
steerable catheter such as an electrophysiology (EP) catheter. One
example of a catheter having a suitable steering mechanism is the
Marinr catheter commercially available from Medtronic
Corporation.
[0140] FIG. 12 is a plan view of a steerable catheter that may be
used to navigate the balloon catheter 200 into the coronary sinus.
The catheter 1000 is an anatomically-conforming, dual curve EP
catheter used to sense electrical signals in the heart and
associated vasculature. The catheter includes a shaft 1004 having
an atraumatic distal end 1006 and a proximal end 1008. Shaft 1004
may have an outside diameter of less than approximately 0.093
inches and a length of about 50 mm to 110 mm. Proximal end 1008 is
mounted to a handle 1010 having axially slidable manipulator rings
1012 and 1013, and a rotatable lateral deflection ring 1014
operably connected to proximal and distal manipulator wires carried
by the body of the catheter. Sliding manipulator rings 1012 and
1013 cause a deflectable tip 1020 of catheter shaft 1004 to deflect
as shown in FIGS. 12A and 12B between, for example, the solid-line
and dashed-line positions of FIG. 12B. Rotating ring 1014 causes
lateral deflection of tip 1020 through the torquing action of a
core wire as shown in FIGS. 12C.
[0141] A steerable EP catheter of the type shown in FIGS. 13A
through 13C may be inserted within the inner lumen of the balloon
catheter, which in turn, is inserted within the lumen 104 of the
outer sheath 100 to create an alternative sheath/catheter
combination. As previously described, this assembly may be advanced
into the chambers of the heart. Next, the EP catheter distal tip
may be advanced beyond the distal end of the outer sheath to guide
the balloon catheter into the coronary sinus. The range of motion
provided by the steerable catheter as noted above makes it
particularly suitable for cannulating the coronary sinus so that
the balloon catheter may then be used to obtain a venogram. Then
the balloon catheter and the steerable catheter are removed from
the sheath so that the sheath may be used to place an IMD with a
microdeflection mechanism in the manner discussed above.
[0142] In yet another manner of using a sheath according to the
current invention, steerable EP catheter 1000 may be pre-loaded
into sheath 130 (FIGS. 1C and 1D). This sheath/catheter combination
may then be advanced into the chambers of the heart, and the distal
tip of this combination used to cannulate the coronary sinus.
Alternatively, the EP catheter distal tip may be advanced beyond
the distal end of sheath 130 to cannulate the coronary sinus, and
the sheath distal end may thereafter be tracked over the EP
catheter into the coronary sinus.
[0143] After the distal end of sheath 130 is seated within the
coronary sinus, EP catheter 1000 may be withdrawn from inner lumen
152. In its place, a balloon catheter such as balloon catheter 200
may be advanced within the lumen to obtain a venogram in the manner
discussed above. Thereafter, the balloon catheter is withdrawn from
the body so that a lead may be advanced within the sheath lumen
into the coronary sinus.
[0144] In one embodiment, the central lumen of lead 600 is
pre-loaded with micro-deflection mechanism 400, or any type of
navigational device such as a stylet or guidewire. The lead is then
advanced through the lumen of sheath 130 into the coronary sinus
ostium as generally shown in FIG. 11. The lead may then be directed
into a branch vein of the coronary sinus using the pre-loaded
device to provide guiding capabilities.
[0145] A method similar to that described in the foregoing
paragraphs may be used with an over-the-wire lead similar to the
2187.TM. model lead commercially-available from Medtronic
Corporation. In this instance, a guidewire may be advanced into the
inner lumen of sheath 130 and beyond the sheath distal end. If
desired, the guidewire may be used to sub-select a branch vein. An
inner lumen of the lead may then be tracked over the guidewire into
the coronary sinus or branch vein. In a similar embodiment, the
guidewire may be preloaded into the lead inner lumen so that the
combination may be advanced within the sheath lumen. The guidewire
may then be advanced beyond the distal end of the sheath to
sub-select a branch vein, and the lead may be tracked over the
guidewire to the target destination.
[0146] In still another embodiment of the above method, sheath 130
is used to sub-select a branch vein of the coronary sinus instead
of a guidewire or other micro-deflection mechanism. As discussed
above, sheath 130 is provided with an extremely soft, flexible,
atraumatic distal tip that minimizes risk of tissue perforation.
Moreover, the sheath is sized for entry into the coronary sinus or
a branch vein. Additionally, because of the inclusion of a braid
such as braid 154 (FIG. 1D), sheath is very pushable. This
combination of characteristics makes sheath 130 ideal for
sub-selecting a branch vein prior to lead placement.
[0147] After a lead or other IMD is positioned at a target
destination, sheath 130 may be withdrawn from the body. This may be
accomplished by slitting the sheath using any commercially
available slitting tool, as is necessary if the lead or other IMD
being positioned by the sheath has a connector that is not
small-profile. As discussed above, the construction of sheath 130
is specifically designed to be slittable despite the inclusion of
braid 154.
[0148] Withdrawal of sheath 130 from the body is made easier by the
use of soft materials within transition section 134 and distal
section 135, and by the use of a substantially straight sheath
configuration. As noted above, these features allow the sheath to
track a lead body without exhibiting a "whipping" effect as may
occur when the sheath exits the coronary sinus. This type of
whipping motion is a common problem associated with prior art
devices, and is known to cause lead dislodgement such that, in some
instances, the entire procedure must be repeated.
[0149] According to another aspect of the invention, the system
described herein may be used for deploying a wide array of devices
other than leads in the coronary venous structure, the pulmonary
venous structure, or any organ with large enough vessels for the
introduction of the system. In addition, the system can be used in
extravascular applications such as in the deployment of cochlear
implants, in body cavities, muscle tissue, and the like.
[0150] The balloon catheter 200 can be used for the introduction of
drugs or other media or agents within a very discrete region of a
vessel. Note that the balloon on the balloon catheter 200 described
herein is optional. The deflectable catheter may be used without a
balloon, for improved access and maneuverability.
[0151] With respect to the micro-deflection mechanism 400, due to
its ability to be scaled to a very small size, it may be used for
interventions into the spinal column, tiny vessels in the brain,
liver, kidney, or any other suitable organ. In addition, sensor
such as electrodes for recording signals and possibly ablating
tissue may be incorporated into the micro-deflection mechanism 400.
Fiber optics for the introduction of light for visualization or
optical recording or sensing may be incorporated into either
deflection mechanism.
[0152] The deflection mechanism may also be used to deliver drugs
or other therapeutic or diagnostic agents or materials as described
above.
[0153] Many alterations and modifications may be made by those
having ordinary skill in the art without departing from the spirit
and scope of the invention. The illustrated variations have been
used only for the purposes of clarity and should not be taken as
limiting the invention as defined by the following claims.
* * * * *