U.S. patent application number 12/932371 was filed with the patent office on 2011-06-23 for devices, systems, and methods for performing atherectomy including delivery of a bioactive material.
This patent application is currently assigned to ATHEROMED, INC.. Invention is credited to Uriel Hiran Chee, Christopher James Danek, Paul Quentin Escudero, Brenda Hann, August Christopher Pombo, Torrey Smith, John T. To.
Application Number | 20110152907 12/932371 |
Document ID | / |
Family ID | 40253771 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110152907 |
Kind Code |
A1 |
Escudero; Paul Quentin ; et
al. |
June 23, 2011 |
Devices, systems, and methods for performing atherectomy including
delivery of a bioactive material
Abstract
Devices, systems, and methods are employed to perform an
atherectomy in an identified region to restore patency to arterial
lesions. A bioactive material is introduced into the identified
region before, after or during performing the atherectomy. The
bioactive material can be introduced, e.g., on a balloon coated
with the bioactive material, which is expanded in contact with the
identified region to deliver the bioactive material. The bioactive
material can be, e.g., at least one of a restenosis-inhibiting
agent, a thrombus-inhibiting agent, and an anti-inflammatory
agent.
Inventors: |
Escudero; Paul Quentin;
(Redwood City, CA) ; To; John T.; (Newark, CA)
; Danek; Christopher James; (San Carlos, CA) ;
Chee; Uriel Hiran; (Santa Cruz, CA) ; Pombo; August
Christopher; (Redwood City, CA) ; Smith; Torrey;
(Redwood City, CA) ; Hann; Brenda; (Menlo Park,
CA) |
Assignee: |
ATHEROMED, INC.
MENLO PARK
CA
|
Family ID: |
40253771 |
Appl. No.: |
12/932371 |
Filed: |
February 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12215752 |
Jun 30, 2008 |
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12932371 |
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11771865 |
Jun 29, 2007 |
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12215752 |
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11567715 |
Dec 6, 2006 |
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11771865 |
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11551191 |
Oct 19, 2006 |
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11567715 |
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61043998 |
Apr 10, 2008 |
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60981735 |
Oct 22, 2007 |
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60806417 |
Jun 30, 2006 |
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60820475 |
Jul 26, 2006 |
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Current U.S.
Class: |
606/159 |
Current CPC
Class: |
A61B 2017/22039
20130101; A61B 2017/320775 20130101; A61B 2017/00685 20130101; A61B
2017/2929 20130101; A61B 17/3207 20130101; A61B 2017/22044
20130101; A61M 25/0138 20130101; A61B 2017/22068 20130101; A61B
2017/22094 20130101; A61B 17/320758 20130101; A61B 2017/320032
20130101; A61B 2017/00309 20130101; A61B 2017/003 20130101 |
Class at
Publication: |
606/159 |
International
Class: |
A61B 17/22 20060101
A61B017/22 |
Claims
1. A method of treating a region of a blood vessel comprising:
identifying for treatment a region of a blood vessel having an
occlusive material, deploying into the identified region a vascular
device comprising a catheter body having at its distal end a cutter
assembly comprising a housing having at least one opening and a
cutter having at least one helical cutting surface configured to
rotate about the central axis relative to the housing to cut and
convey occlusive material from the identified region proximally
into the housing, a drive mechanism at a proximal end of the
catheter body, a torque shaft coupled to the drive mechanism and
extending through the catheter body and coupled to the cutter to
rotate the helical cutting blade about the center axis relative to
the housing, and a conveyor mechanism helically wound about the
torque shaft in a direction common with the helical cutting blade
to rotate and thereby convey the occlusive material conveyed into
the housing by the helical cutting blade further proximally along
the catheter body for discharge without supplement of a vacuum
pump, performing an atherectomy in the identified region by
operating the drive mechanism to rotate the helical cutting surface
to cut and convey occlusive material from the identified region
proximally into the housing, the drive mechanism also operating to
rotate the conveyor mechanism to convey the occlusive material
further proximally along the catheter body for discharge without
supplement of a vacuum pump, and introducing into the identified
region a bioactive material before, after or during performing the
atherectomy in the identified region.
2. A method of treating a region of a blood vessel comprising:
identifying for treatment a region of a blood vessel having an
occlusive material, deploying into the identified region a vascular
device comprising a catheter body having at its distal end a cutter
assembly comprising a housing having at least one opening and a
cutter having at least one helical cutting surface configured to
rotate about the central axis relative to the housing to cut and
convey occlusive material from the identified region proximally
into the housing, a drive mechanism at a proximal end of the
catheter body, and a deflecting mechanism at the proximal end of
the catheter body for deflecting the distal end of the catheter
body relative to a center axis of the catheter body, performing an
atherectomy in the identified region by operating the drive
mechanism to rotate the helical cutting surface to cut and convey
occlusive material from the identified region proximally into the
housing, and deflecting the distal end of the catheter body
relative to a center axis of the catheter body, and rotating the
distal end of the catheter body while the distal end is deflected
to sweep the cutter assembly in an arc about the center axis to cut
the occlusive material in a region larger than an outside diameter
of the cutter assembly, and introducing into the identified region
a bioactive material before, after or during performing the
atherectomy in the identified region.
3. A method according to claim 1 or 2 wherein introducing into the
identified region a bioactive material comprises introducing at
least one of a restenosis-inhibiting agent, a thrombus-inhibiting
agent, and an anti-inflammatory agent.
4. A method according to claim 1 or 2 wherein introducing into the
identified region a bioactive material comprises introducing into
the identified region a balloon coated with a bioactive material,
and expanding the balloon in contact with the identified region to
deliver the bioactive material.
5. A method according to claim 1 or 2 and further including
visualizing the identified region before, during, and after
performing the atherectomy.
6. A method according to claim 1 or 2 and further including after
conveying at least some of the occlusive material from the
identified region, placing a stent structure in the identified
region.
7. A method according to claim 6 and further including after
placing the stent structure, performing an atherectomy to remove
residual occlusive material from the stent structure.
8. A method according to claim 6 and further including after
placing the stent structure, introducing into the stent structure a
bioactive material.
9. A method according to claim 6 and further including after
placing the stent structure, introducing into the stent structure a
bioactive material comprising at least one of a
restenosis-inhibiting agent, a thrombus-inhibiting agent, and an
anti-inflammatory agent.
10. A method according to claim 1 or 2 wherein the blood vessel is
a peripheral blood vessel.
11. A method according to claim 1 or 2 wherein the blood vessel is
a peripheral blood vessel in a leg.
12. A method according to claim 1 or 2 wherein the blood vessel is
a peripheral blood vessel in a leg below a knee.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 12/215,752, filed Jun. 30, 2008 and entitled
"Atherectomy Devices, Systems, and Methods," which claims the
benefit of U.S. Provisional Patent Application Ser. No. 61/013,998,
filed Apr. 10, 2008, and entitled "Atherectomy Devices and
Methods," which is incorporated herein by reference.
[0002] This application also claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/981,735, filed Oct. 22, 2007, and
entitled "Atherectomy Devices and Methods," which is incorporated
herein by reference.
[0003] This application is also a continuation-in-part of
co-pending U.S. patent application Ser. No. 11/771,865, filed Jun.
29, 2007, and entitled "Atherectomy Devices and Methods," which is
a continuation-in-part of co-pending U.S. patent application Ser.
No. 11/567,715, filed Dec. 6, 2006, and entitled "Atherectomy
Devices and Methods," which is a continuation of co-pending U.S.
patent application Ser. No. 11/551,191, filed Oct. 19, 2006, and
entitled "Atherectomy Devices and Methods," which claims the
benefit of U.S. Provisional Patent Application Ser. No. 60/806,417,
filed Jun. 30, 2006, end entitled "Atherectomy Device," and which
also claims the benefit of U.S. Provisional Patent Application Ser.
No. 60/820,475, filed Jul. 26, 2006, end entitled "Atherectomy
Device," which are all incorporated herein by reference.
FIELD OF THE INVENTION
[0004] The devices, systems, and methods generally relate to
treatment of occluded body lumens, e.g., for removal of occluding
material from a blood vessel as well as other body parts.
BACKGROUND OF THE INVENTION
I. Peripheral Arterial Disease
[0005] Peripheral Arterial Disease (PAD) is a progressive disease.
In this disease, lesions of the arteries are formed by accumulation
of plaque and neointimal hyperplasia causing an obstruction of
blood flow. Plaque (the build-up of cholesterol, cells, and other
fatty substances) is often friable and may dislodge naturally or
during an endovascular procedure, possibly leading to embolization
of a downstream vessel.
[0006] It is estimated that 12 million people in the United States
suffer from PAD that if left untreated has a mortality rate of 30
percent at five years. There are approximately 160,000 amputations
each year from critical limb ischemia, the most severe subset of
patients having PAD. The prevalence of PAD is on the rise, with
risk factors including age, obesity, and diabetes.
[0007] Endovascular clearing procedures to reduce or remove the
obstructions to restore luminal diameter and allow for increased
blood flow to normal levels are known. Removing the plaque has the
effect of removing diseased tissue and helps to reverse the
disease. Maintaining luminal diameter for a period of time (several
to many weeks) allows remodeling of the vessel from the previous
pathological state to a more normal state. It is also the goal of
an endovascular clearing procedure to prevent short term
complications such as embolization or perforation of the vessel
wall, and long term complications such as ischemia from thrombosis
or restenosis.
II. Prior Treatment Modalities
[0008] Unlike coronary artery disease, current treatment options
for PAD, including PAD in the arteries of the leg, have significant
limitations for at least three main reasons: A) large volumes of
plaque build up in very long, diffuse lesions, B) low blood flow
promotes thrombus formation and plaque buildup, and C) arteries of
the leg are bent, twisted, stretched, and pinched shut during
routine movement.
[0009] Various treatment modalities have been tried to accomplish
treatment goals. In atherectomy, plaque is cut away, or excised.
Various configurations have been used including a rotating
cylindrical shaver or a fluted cutter. The devices may include some
form of shielding by a housing for safety purposes. The devices may
incorporate removal of debris via trapping the debris in the
catheter, in a downstream filter, or aspirating the debris, for
example. In some cases a burr may be used instead of a cutter,
particularly to grind heavily calcified lesions into very small
particle sizes. Aspiration may also be used with a burr-type
atherectomy device.
[0010] A current example of an atherectomy device is the
SilverHawk.RTM. Plaque Excision System by Fox Hollow Technologies.
The SilverHawk has a number of limitations including the length of
time the procedure takes to clear a lumen, it requires multiple
devices and repeated catheter exchanges, it produces embolic
debris, and it uses an unguarded cutter design that requires great
patience and care to open the lumen while sparing the vessel wall.
In use, the physician advances the catheter through the lesion,
shaving plaque off of the artery walls and collecting the plaque in
a long receptacle (nosecone) at the tip of the catheter (which must
have enough room in the vessel to pivot to access the cutting
blade). As the receptacle fills, the catheter must be removed, the
receptacle emptied, and the procedure repeated until enough plaque
is removed to restore normal blood flow. The procedure may include
replacing the catheter with a larger diameter catheter to expand
the size of the clearing. The long receptacle at the tip of the
catheter limits the use of the device to mainly straight
lumens.
[0011] Balloon angioplasty is another type of endovascular
procedure. Balloon angioplasty expands and opens the artery by both
displacing the plaque and compressing it by expanding a balloon in
the artery, with some variations including a drug coated balloon.
Balloon angioplasty is known to cause barotrauma to the vessel from
the high pressures required to compress the plaque, and can also
cause dissection of the vessel wall. This trauma leads to an
unacceptably high rate of restenosis. Furthermore, this procedure
may not be efficient for treatment of elastic-type plaque tissue,
where such tissue can spring back to occlude the lumen.
[0012] Cryoplasty has been available for only a few years and has
provided only limited positive results. With cryoplasty, the main
problem appears to be restenosis after an extended period, such as
a year. The technique is similar to balloon angioplasty procedures
used in heart vessels, except stents are not used to keep the blood
vessel open. With cryoplasty, the balloon is cooled to about -10
degrees Celsius (14 degrees Fahrenheit) by evaporating liquid
nitrous oxide into a gas upon entering the balloon. The plaque
clogging the artery cracks when it freezes, allowing for a more
uniform dilation of the blood vessel than occurs in a standard
angioplasty procedure.
[0013] Various forms of laser atherectomy have been developed and
have had mixed results. One main limitation of a laser system is
that the laser can only be effectively used in a straight lumen,
and is less effective in or around tortuous lumens. When the laser
is in position, it emits pulsating beams of light that vaporize the
plaque. Laser systems have been less effective for removing
calcified legions because of the laser properties.
[0014] Stenting may also be used as a treatment option. On their
own, stents, including drug eluding stents, fail to perform well in
the peripheral vasculature for a variety of reasons. A stent with
the necessary structural integrity to supply sufficient radial
force to reopen the artery often does not perform well in the harsh
mechanical environment of the peripheral vasculature. For example,
the peripheral vasculature encounters a significant amount of
compression, torsion, extension, and bending. Such an environment
may lead to stent failure (strut fracture, stent crushing, etc.)
that eventually compromises the ability of the stent to maintain
lumen diameter over the long-term. Stenting is also susceptible to
in-stent restenosis, typically at a restenosis rate of 30 percent
or higher. Stent fracture or restenosis may require subsequent
vascular bypass surgery, which is invasive and is limited in the
types of lesions or artery obstructions that may produce acceptable
results. Stenting is not advisable in regions which would be
candidates for proximal or distal anastomosis during surgical
bypass procedures, because a stent in that region makes bypass
difficult or impossible.
[0015] On the other hand, a stent that is able to withstand the
harsh mechanical aspects of the periphery often will not supply
enough radial force to open the vessel satisfactorily. In many
cases, medical practitioners desire the ability to combine
endovascular clearing procedures with stenting. Such stenting may
occur prior to, after, or both before and after the endovascular
clearing procedure.
[0016] Accordingly, a need remains for devices, systems, and
methods that allow for improved atherectomy systems that are able
to navigate through tortuous anatomy and clear materials from body
lumens (such as blood vessels) where the systems includes features
to allow for a safe, efficient and controlled fashion of shaving or
grinding material within the body lumen while minimizing procedure
times. In addition, there remains a need for systems that allow
steering of the distal portion of the system while navigating
through tortuous anatomy. The ability to steer assists the
physician in accessing tortuous anatomy and can further assist in
delivering a guidewire into the entrance of angled or tortuous
vessel bifurcation/segments. This is possible because variations of
the steerable atherectomy catheter system described herein can also
function as a `shuttle catheter`, where the physician can aim the
distal tip into the vessel to be accessed and advancing the
guidewire into that vessel from within the catheter
[0017] There also remains a need for devices that are configured to
steer but will remain in a straight configuration when not being
articulated. It is generally known that conventional catheters that
take a shape often bias to one side either through repeated
articulation or even after being left in packing for any given
period of time. Accordingly, when such steering features are
combined with tissue debulking systems, there remains a risk of
injury if the tissue debulking system has an undesirable bend when
the device is intended to be in a straight configuration.
[0018] The debulking devices, systems, and methods described herein
address the problems noted above as well as provide significant
improved features to allow a physician to steer a debulking device
through tortuous anatomy and remove tissue at a target site.
SUMMARY OF THE INVENTION
[0019] One aspect of the invention provides a method for treating a
region of a blood vessel. The method includes deploying a vascular
device into a region of a blood vessel having an occlusive
material. The vascular device comprises a catheter body having at
its distal end a cutter assembly. The cutter assembly comprises a
housing having at least one opening and a cutter having at least
one helical cutting surface configured to rotate about the central
axis relative to the housing to cut and convey occlusive material
from the region proximally into the housing. The vascular device
also includes a drive mechanism at a proximal end of the catheter
body, and a torque shaft coupled to the drive mechanism and
extending through the catheter body and coupled to the cutter to
rotate the helical cutting blade about the center axis relative to
the housing.
[0020] In one embodiment, the vascular device includes a conveyor
mechanism helically wound about the torque shaft in a direction
common with the helical cutting blade to rotate and thereby convey
occlusive material from the region further proximally along the
catheter body for discharge without supplement of a vacuum pump. In
this embodiment, the method comprises performing an atherectomy in
the identified region by operating the drive mechanism to rotate
the helical cutting surface to cut and convey occlusive material
from the identified region proximally into the housing, the drive
mechanism also operating to rotate the conveyor mechanism to convey
the occlusive material further proximally along the catheter body
for discharge without supplement of a vacuum pump. The method can
include visualizing the identified region before, during, and after
performing the atherectomy.
[0021] In one embodiment, the vascular device includes a deflecting
mechanism at the proximal end of the catheter body for deflecting
the distal end of the catheter body relative to a center axis of
the catheter body. In this embodiment, the method comprises
performing an atherectomy in the identified region by operating the
drive mechanism to rotate the helical cutting surface to cut and
convey occlusive material from the identified region proximally
into the housing, and deflecting the distal end of the catheter
body relative to a center axis of the catheter body, and rotating
the distal end of the catheter body while the distal end is
deflected to sweep the cutter assembly in an arc about the center
axis to cut the occlusive material in a region larger than an
outside diameter of the cutter assembly. The method can include
visualizing the identified region before, during, and after
performing the atherectomy.
[0022] According to this aspect of the invention, in either
embodiment, the method includes introducing into the identified
region a bioactive material before, after or during performing the
atherectomy in the identified region. Introducing the bioactive
material can comprise, e.g., introducing into the identified region
a balloon coated with a bioactive material, and expanding the
balloon in contact with the identified region to deliver the
bioactive material. The bioactive material can comprise, e.g., at
least one of a restenosis-inhibiting agent, a thrombus-inhibiting
agent, and an anti-inflammatory agent.
[0023] In one embodiment, the method further includes after
conveying at least some of the occlusive material from the
identified region, placing a stent structure in the identified
region. In one embodiment, after placing the stent structure, the
method further includes performing an atherectomy to remove
residual occlusive material from the stent structure. In one
embodiment, the method includes, after placing the stent structure,
introducing a bioactive material into the stent structure. The
bioactive material can comprise, e.g., at least one of a
restenosis-inhibiting agent, a thrombus-inhibiting agent, and an
anti-inflammatory agent.
[0024] The blood vessel can comprise, e.g., a peripheral blood
vessel, e.g., a peripheral blood vessel in a leg, or a peripheral
blood vessel in a leg below a knee.
[0025] As noted herein, combinations of aspects of the devices,
systems, and methods described herein may be combined as needed.
Furthermore, combinations of the devices, systems and methods
themselves are within the scope of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1A is a perspective view of a system adapted for the
removal of occluding material from body lumens according to the
present invention.
[0027] FIG. 1B is a close up perspective view of the distal tip of
the system shown in FIG. 1A, showing an embodiment of a cutting
assembly.
[0028] FIG. 2A is a perspective exploded view showing the cutting
assembly of FIG. 1B.
[0029] FIG. 2B is a perspective view of a two piece cutter shown in
FIG. 2A.
[0030] FIGS. 3A to 3C show a cutter assembly having a dynamic
housing where the external housing acts as a cutter in conjunction
with an internal two flute cutter.
[0031] FIG. 3D shows an exploded view of the cutter assembly of
FIG. 3C.
[0032] FIG. 3E shows a perspective view of a cutter assembly with a
dynamic housing removing material from a lumen wall.
[0033] FIGS. 4A and 4B shows placement of features of the cutter
assembly that prevent damage to the vessel walls.
[0034] FIG. 5A shows a perspective view of a variation of an open
ended cutter housing with an inner bevel.
[0035] FIG. 5B shows a cross sectional side view of the open ended
cutter of FIG. 5A taken along lines 5B-5B.
[0036] FIGS. 6A and 6B show variations of cutting assemblies for
removing tissue from body lumens.
[0037] FIGS. 7A through 7F show additional variations for centering
devices within a lumen.
[0038] FIG. 8A is a perspective view in partial section of a distal
portion of a system adapted for the removal of occluding material
from body lumens, showing an embodiment of a sweep sheath.
[0039] FIG. 8B is a perspective exploded view showing an additional
embodiment of a cutting assembly with a one piece cutter.
[0040] FIG. 9 is a perspective exploded view showing an additional
embodiment of a cutting assembly with a two piece cutter.
[0041] FIG. 10 shows a cross sectional view of the cutting assembly
shown in FIG. 8A.
[0042] FIG. 11A shows the cutting edges through openings of a
housing.
[0043] FIG. 11B shows a side view of the cutting assembly of FIG.
11A.
[0044] FIG. 11C shows a front view of the cutting assembly of FIG.
11A, and showing a positive rake angle.
[0045] FIG. 12 is a perspective view of an embodiment of a guarded
housing having a dilation member.
[0046] FIGS. 13A through 13C are side views showing the use of a
debulking device having a dilating member as seen in FIG. 12.
[0047] FIGS. 14A and 14B show an additional embodiment of a
shielded cutter having a plurality of front cutting surfaces and
fluted cutting surfaces.
[0048] FIG. 15 is a perspective view of a cutting assembly having a
guarded housing and incorporating a burr tip.
[0049] FIGS. 16A and 16B show a variation of a shielded cutter
having a plurality of front cutting surfaces, rear cutting
surfaces, and fluted cutting surfaces.
[0050] FIG. 17 is a perspective view in partial section of a distal
portion of a system adapted for the removal of occluding material
from body lumens, showing the catheter body, a sweep sheath, a
torque shaft, and a conveying member.
[0051] FIGS. 18A and 18B show additional possible variations a
catheter body or sweep member.
[0052] FIG. 18C is a side view of an alternative embodiment of a
catheter body including a multi-body design having minimal
torsional losses while maximizing bending in a first portion and
longitudinal stiffness in a second portion.
[0053] FIG. 18D is a detail view of the first and second section of
FIG. 18C, showing one embodiment of a dovetail design for the first
section.
[0054] FIG. 18E is a detail view of an alternative embodiment of
the first section of FIG. 18C, showing an additional embodiment of
a dovetail design for the first section.
[0055] FIG. 18F is a side view of the catheter body including a
multi-body design of FIG. 18C, showing a flexed distal portion.
[0056] FIG. 19A shows a conveying member within the catheter body
and sweep frame.
[0057] FIG. 19B shows an embodiment of a conveying member wound
around the torque shaft, as seen in FIG. 17.
[0058] FIG. 19C shows a partial cross sectional view of a variation
of a conveying member and a torque shaft having counter wound
coils.
[0059] FIG. 19D shows a second conveying member within a torque
shaft.
[0060] FIG. 19E is a perspective view of an alternative torque
shaft including a wound groove as the conveying member.
[0061] FIG. 20A is a perspective view in partial section similar to
FIG. 17, showing the sweep frame causing angular deflection of the
distal portion of the catheter.
[0062] FIG. 20B is a side view of the distal portion of the
catheter shown in FIG. 20A, with the sweep frame in an unflexed
position.
[0063] FIG. 20C is a perspective view in partial section similar to
FIG. 20A, showing a sweep member abutting the sweep frame, with the
sweep frame causing angular deflection of the distal portion of the
catheter, where the sweep frame is flexed or compressed to
articulate the catheter up to a predefined angle.
[0064] FIGS. 21A through 21C show additional variations of sweep
frames for use with the debulking devices described herein.
[0065] FIG. 22A illustrates articulation of the distal portion of
the catheter around a tortuous bend to reach a lesion for
removal.
[0066] FIG. 22B through 22D shows variations of sweeping of the
cutting assembly, with the sweep being able to rotate 360 degrees
or more.
[0067] FIG. 22E a cross sectional view of a vessel, and showing the
ability of the system to clear a lumen in a vessel up to four times
the diameter of the catheter.
[0068] FIGS. 23A through 23H show the debulking system in use for
both passive and active steering through a tortuous vessel and to a
treatment site.
[0069] FIGS. 24A through 24C illustrate the use of a debulking
device to assist in the navigation of a guidewire through tortuous
anatomy and occluding material.
[0070] FIG. 24D shows placement of housing windows to prevent
damage to the vessel walls, and apposition of the catheter against
the vessel wall.
[0071] FIG. 25A shows an exploded view of a control handle for the
debulking system, the handle adapted for rotating and articulating
the distal portion of the catheter, including the cutter
assembly.
[0072] FIG. 25B is a side view in partial section showing the
handle base portion adapted to house functional elements of the
control handle, and to isolate functions of the control handle from
the catheter chassis.
[0073] FIGS. 26A through 26C show side views of the flexible distal
portion of the catheter having an adjustable flexible distal
length, and also adapted for orbital rotation possibly using an
element of unbalance.
[0074] FIG. 27 is a perspective view of the catheter chassis
portion adapted to snap fit within the handle base portion, and
including the control mechanisms for steering and sweeping,
irrigation, aspiration, and rotation of the torque shaft.
[0075] FIGS. 28A and 28B an indexing cassette and associated spring
plunger, as seen in FIG. 27, the indexing cassette and associated
spring plunger adapted for fine tune control for cutter assembly
deflection and steering features.
[0076] FIGS. 29A and 29B show a debulking system, including a
control handle for the system, the handle adapted for rotating and
articulating the distal portion of the catheter, including the
cutter assembly.
[0077] FIG. 30 shows a schematic view of the debulking system, the
system cutting debris, and aspirating the debris through the
catheter, into the catheter chassis, and out the aspiration
port.
[0078] FIGS. 31A and 31B show variations of a sweep frame having a
visualization feature that permits a physician to determine
orientation and direction of articulation of the cutting assembly
when the device is viewed under non-invasive imaging.
[0079] FIGS. 32A through 32C provide examples of fluid delivery
systems.
[0080] FIG. 33 shows a variation of a device configured for rapid
exchange.
[0081] FIG. 34 illustrates an example of centering a tip of a
cutting assembly over a guide wire.
[0082] FIG. 35 shows a cutting assembly removing lesions within a
stent or coil.
[0083] FIG. 36 shows an anatomic view of the lower limb of an
animal, including a human, and showing a representation of the
arteries within the lower limbs.
[0084] FIG. 37A shows an anatomic view similar to FIG. 36, and
showing a contralateral configuration for a possible access site
for the system to be used in the vasculature for the removal of
lesions.
[0085] FIG. 37B shows a detail view of FIG. 37A, the detail view
showing the catheter 120 extending through the external iliac
artery, through tortuous vessels, and into the profunda artery for
debulking of an occlusion.
[0086] FIG. 38A shows an anatomic view similar to
[0087] FIG. 35, and showing an additional possible ipsilateral
access site for the system to be used in the vasculature for the
removal of lesions.
[0088] FIG. 38B shows a detail view of FIG. 38A, the detail view
showing the catheter 120 extending through the popliteal femoral
artery, through tortuous vessels, and into the anterior tibial
artery for debulking of an occlusion.
[0089] FIG. 39 is a view of a set of components of the system
consolidated for use in a multiple piece kit, along with
instructions for their use.
[0090] FIGS. 40A and 40B show a distal portion of a debulking
catheter including a balloon or other mechanism for adjunctive
angioplasty, stent, and/or other drug delivery.
[0091] FIGS. 41A and 41B are side views of an embodiment of a
debulking system, the system including a transducer and/or sensor
to provide imaging of the targeted treatment site before and/or
after treatment.
[0092] FIG. 42 is a side view of an embodiment of a debulking
system, the system including an imaging system at or near a distal
end to provide imaging of the targeted treatment site before and/or
after treatment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0093] Although the disclosure hereof is detailed and exact to
enable those skilled in the art to practice the invention, the
physical embodiments herein disclosed merely exemplify the
invention which may be embodied in other specific structures. While
the preferred embodiment has been described, the details may be
changed without departing from the invention, which is defined by
the claims.
[0094] This specification discloses various catheter-based devices,
systems, and methods for removing occluding materials from body
lumens, including removing plaque, thrombus, calcium, and soft
elastic tissues in blood vessels. For example, the various aspects
of the invention have application in procedures requiring the
treatment of diseased and/or damaged sections of a blood vessel.
The devices, systems, and methods that embody features of the
invention are also adaptable for use with systems and surgical
techniques that are not necessarily catheter-based.
[0095] The devices, systems, and methods are particularly well
suited for continuous debulking and aspiration of occluding
material in the peripheral vasculature, including arteries found in
the legs, such as the common femoral artery, superficial femoral
artery, profunda femorus artery, popliteal artery, and tibial
artery, as non-limiting examples. For this reason, the devices,
systems, and methods will be described in this context. Still, it
should be appreciated that the disclosed devices, systems, and
methods are applicable for use in treating other dysfunctions
elsewhere in the body, which are not necessarily
artery-related.
[0096] When referring to catheter based apparatus or devices that
are manipulated by a physician or operator in order to remove
occluding materials from a body lumen, the terms "proximal" and
"distal" will be used to describe the relation or orientation of
the apparatus or device with respect to the operator as it is used.
Therefore, the term "proximal" will be used to describe a relation
or orientation of the apparatus or device that, when in use, is
positioned toward the operator (i.e., at the "handle" end of the
device), and the term "distal" will be used to describe a position
or orientation of the apparatus or device that, when in use, is
positioned away from the operator (i.e., at the "cutter" end of a
catheter or the like away from the handle).
[0097] When referring to plaque in a vessel, or a partial or
complete blockage in a vessel or body organ, the terms "proximal"
and "distal" will be used to describe the relation or orientation
of the plaque or blockage with respect to the heart. Therefore, the
term "proximal" will be used to describe a relation or orientation
of the plaque or blockage that is toward the heart, and the term
"distal" will be used to describe a position or orientation of the
plaque or blockage that is away from the heart, i.e., toward the
feet.
I. System Overview
[0098] A. System Capabilities
[0099] FIGS. 1A and 1B illustrate an exemplary variation of a
system 100 according to the present invention, the system 100
adapted for thrombectomy and/or atherectomy. As shown, the system
100 includes a distal cutter assembly 102 affixed to a catheter
body or catheter assembly 120, with the catheter assembly coupled
to a control handle 200 at a proximal end. It is noted that the
assemblies shown in the figures are for exemplary purposes only.
The scope of this disclosure includes the combination of the
various embodiments, where possible, as well as the combination of
certain aspects of the various embodiments.
[0100] The system 100 provides substantial ease of use,
performance, and safety advantages over prior debulking types of
devices. As will be described in greater detail throughout this
specification and Figures, the system 100 may include 360 degree
steerable rotational cutting, a guarded (shielded) or open cutter
at the distal end of a catheter, with the catheter coupled to a
hand-held controller (i.e., handle) that is adapted to allow
continuous debulking and aspiration of lesions ranging from fresh
thrombus to calcified plaque. The debris is trapped within the
catheter as it is cut, and may be continuously removed.
[0101] The devices, systems, and methods described herein work
particularly well in lesions that are challenging to treat with
other systems, i.e., at bifurcations, in tortuous arteries, and in
arteries which are subject to biomechanical stresses, such as
arteries in the periphery, e.g., located within the knee or other
joints (as will be described in greater detail later).
[0102] The devices, systems, and methods can also perform a wide
variety of other treatments, including biopsies, tumor removal,
fibroid treatment, debulking of unwanted hyperplastic tissues such
as enlarged prostate tissue, or other unwanted tissue such as
herniated spinal disc material. Any of the devices, systems, and
methods described herein may also be used as a tool to treat
chronic total occlusions (CTO) or a complete blockage of the
artery. The flexible, low profile catheter systems described herein
allow for ease of access to the treatment site and minimizes trauma
or collateral damage to surrounding healthy tissue. With a
continuous aspiration capability, contamination of the surrounding
tissue during device introduction, treatment, and removal is
reduced or even eliminated. In addition, aspiration can be used to
transfer biopsy tissue samples to outside the body for testing with
the catheter remaining in situ. This helps the physician make real
time decisions in advancing treatment of malignant tissue.
[0103] A shield or housing on the cutter assembly 102 maintains
controlled excision of tissue by limiting the depth of cutter
engagement and thereby prevents the physician from inadvertently
cutting into healthy surrounding tissue. The tip steering
capability of the system allows the physician to direct the cutter
108 towards desired site of tissue removal and minimizing
collateral tissue damage. By deflecting the cutter and rotating the
deflection to sweep in an arc, the catheter can excise large plaque
deposits, tumors, or tissue lumps larger than the diameter of the
catheter. Thus, excision of large tumors can be achieved through a
small access channel and thereby minimizing trauma to the
patient.
[0104] The devices, systems, and methods described herein can also
debulk stenosis in arteriovenous (AV) hemodialysis access sites
(fistulae and synthetic grafts), as well as to remove thrombus. For
example, by removing the cutter housing and recessing the fluted
cutter within the catheter body, a suitable non-cutting
thrombectomy catheter may be constructed.
[0105] The devices, systems, and methods described herein can also
be used for excising bone, cartilage, connective tissue, or muscle
during minimally invasive surgical procedures. For example, a
catheter that includes cutting and burr elements may be used to
gain access to the spine for performing laminectomy or facetectomy
procedures to alleviate spinal stenosis. For this application, the
catheter may be further designed to deploy through a rigid cannula
over part of its length, or have a rigid portion itself, to aid in
surgical insertion and navigation.
[0106] It is also possible to use the devices, systems, and methods
described herein to restore patency to arterial lesions in the
coronary circulation and in the cerebrovascular circulation, both
by debulking de novo lesions and by debulking in-stent restenosis.
FIG. 35 shows the system 100 removing lesions within a stent or
coil.
II. Desirable Technical Features
[0107] The debulking system 100 can incorporate various technical
features to enhance its usability, which will now be described.
[0108] A. The Cutter Assembly
[0109] 1. Cylindrical Housing Cutter Assemblies
[0110] FIG. 2A illustrates an exploded view of an exemplary
embodiment of a front cutting cutter assembly 102. In this
variation, the cutter assembly 102 includes a cylindrical housing
104 having an opening 107 located on its distal face adapted to
allow a cutter 108 to extend beyond the distal face. The cutter 108
may comprise one or more cutting edges. In the illustrated
embodiment, the cutting edges comprise a first set of cutting edges
112 that extend along (or substantially along) the cutter 108 and a
second cutting edge 109 that extends only along a portion of the
cutter 108. Although the number of cutting edges can vary,
typically the cutting edges will be symmetric about an axis 111 of
the cutter 108.
[0111] FIG. 2B also shows a variation of the cutter 108 that
comprises a distal portion 90 mounted on a proximal portion 92
(where the proximal cutter portion 92 can also be referred to as a
cutter core adapter 92). The proximal cutter portion 92 contains a
shaft 94 terminating in a mating piece 140, with the mating piece
140 nested within an opening in the front face of the distal cutter
90. The cutter assembly 102 can also include a guidewire lumen 130
to allow for passing of a guidewire through the cutter assembly 102
and device 100.
[0112] The cutter 108, as described herein, is preferably made of
hard, wear-resistant material such as hardened tool or stainless
steels, Tungsten carbide, cobalt chromium, or titanium alloys with
or without wear resistant coatings, such as Titanium Nitride.
However, any material commonly used for similar surgical
applications may be employed for the cutter. The outer surfaces of
the proximal end of the cutter 108 are typically blunt and are
designed to bear against the housing 104. Typically, these surfaces
may be parallel to the inner surface of the housing 104.
[0113] FIGS. 3A to 3E illustrate additional variations of the
cutter assembly 102. In such a variation, the front edge of the
housing 104 can function as a front or forward cutting surface 113.
In one variation, the cutter 108 may be tapered or rounded such
that the front of the cutter comprises a rounded or partial-ball
shape. As shown, the front cutting surface 113 can be beveled on an
outside surface of the housing 104. Such a beveled feature reduces
the risk of the cutting surface 113 from gouging or otherwise
damaging the wall of a vessel. As noted above, the forward cutting
surface 113 engages and removes tissue or plaque 4 when the device
is advanced in a distal direction within a body lumen 2 as shown in
FIG. 3F. As discussed herein, features of the device 100 include a
guidewire 128 to assist in preventing the device from excessively
cutting the lumen wall 2.
[0114] The housing 104 can either be configured to rotate with the
cutter 108 or can be stationary and function as a scraping,
scooping, or chisel type surface. For example, FIGS. 3A and 3B show
a variation where the housing 104 can be affixed to the cutter 108
allowing for rotation of the entire cutting assembly 102 about the
catheter body 120. The system may also include a ferrule 116 that
permits coupling of the catheter body 120 to the cutter assembly
102. The ferrule 116 may serve as a bearing surface for rotation of
the cutter 108 within the cutter assembly 102. In the illustrated
example, the cutting assembly 102 includes adjoining recessed pin
cavities 103 for securing the housing 104 to the cutter 108. FIG.
3B shows a cross sectional view of the cutter assembly 102 of FIG.
3A. As illustrated, in this particular variation, the entire
cutting assembly 102 rotates relative to the ferrule 116 which
provides a bearing surface for the rotational housing 104. The
proximal portion 92 of the cutter 108 rotates within the ferrule
while the proximal end of the housing 104 rotates about the ferrule
116.
[0115] The housing 104 can be linked to the cutter 108 in a variety
of ways as is well understood by those skilled in the art. For
example the housing 104 can be directly linked or affixed to the
cutter 108 via connection points 103 so that both rotate together.
Alternatively, the housing 104 can be geared to rotate faster or
slower than the cutter 108. In yet another variation, the gearing
can be chosen to permit the housing 104 to rotate in an opposite
direction than the cutter 108.
[0116] Variations of the cutting assemblies include cutters 108
that protrude partially from the forward cutting surface 113 of the
housing 104. In other variations, the cutter 108 can extend further
from the housing 104 or the assemblies can comprise cutters 108
that are totally recessed within the housing 104. In certain
variations, it was identified that aligning the cutting surface 113
of the housing 104 with the deepest part of a flute 110 on the
cutter 108 allows for improved clearing of debris, especially where
a single or double fluted cutting edge configuration is used on a
distal portion of the cutter 108.
[0117] In any case, the fluted cutting edge 112 impels tissue
debris back into the catheter. The outer surface of the housing,
proximal to the forward cutting surface 113 can be smooth to
protect the lumen wall from the cutting action of the cutting
edges. When the cutting assembly 102 is deflected, the outer
surface of the housing 104 becomes flush against the lumen wall and
prevents the cutting edges from engaging the vessel wall. As the
cutter assembly is advanced forward, it removes plaque 4 protruding
from the lumen 2 wall and tissue debris is impelled backwards by
the fluted edge 112 of the cutter 108.
[0118] FIG. 3C illustrates an additional variation of a cutting
assembly 102 where a housing 104 of the cutting assembly 102
remains stationary about a catheter body 120 or ferrule 116 while
the cutter 108 rotates within the ferrule. In this embodiment, the
inner portion of the ferrule 116 may provide a bearing surface for
the proximal end 92 of the cutter 108. The housing 104 may be
affixed to the ferrule 116 and may also function as a bearing
surface for the rotating cutter 108.
[0119] The cutter 108 rotates relative to the housing 104 such that
the cutting surface 112 on the cutter 108 shears or cleaves tissue
and traps the tissue inside the housing 104 so that it can be
evacuated in a proximal direction using the impeller action of the
helical flutes 110 and vacuum from the torque shaft 114 and/or
conveying member 118.
[0120] FIG. 3E shows an exploded view of the cutting assembly of
FIG. 3C. Again, the cutter 108 can include a distal cutting portion
90 and a proximal cutting portion 92. The illustrated configuration
provides a device having fewer cutting edges 112 on a distal
portion 90 of the cutter and increased cutting edges 109 and 112 on
a proximal cutting portion 92. However, variations include a
traditional fluted cutter as well. The housing 104 is mounted about
the cutter portions 90 and 92 and optionally secured to either the
catheter body 120 or ferrule 116. As noted above, the housing 104
can also be affixed to the cutter so that it rotates with the
cutter.
[0121] In alternate variations, the mating surface 140 of the
cutter assembly 102 can function as a blunt bumper at the very tip
of the cutter 108 that acts as a buffer to prevent accidental
cutting into the guidewire or the vessel wall given the cutter
assemblies' open distal design. In additional variations, the
housing 104 could be expandable (such as a basket or mesh). As the
cutter 108 gyrates inside the housing, the housing may be adapted
to expand to cut a larger diameter.
[0122] FIG. 3F illustrates a cutting assembly 102 having a forward
cutting surface 113 at a distal opening 117 of a housing 104. The
housing 104 rotates along with the cutter 108 to assist in removal
of tissue. As noted above, the forward cutting surface 113 engages
and removes tissue or plaque 4 when the device is advanced in a
distal direction within a body lumen 2. As discussed below,
features of the device, including a guidewire 128 assist in
preventing the device from excessively cutting the lumen wall
2.
[0123] FIGS. 4A and 4B show a cutter assembly 102 adapted for
forward cutting. This embodiment includes an open ended housing 104
where the cutter extends distally from the housing. However, a
blunt bumper 119 at the distal tip of the cutter 108 acts as a
buffer to prevent accidental cutting into the guidewire 128 or
excessively into the lumen wall 2. In addition, this embodiment can
optionally incorporate an additional housing portion 121 on a back
end of the cutter assembly 102 that partially shields the cutter
108 from deep side cuts into the lumen wall 2.
[0124] Referring to FIG. 2A, a torque shaft 114 rotates inside the
outer catheter body 120, sweep frame 250 and ferrule 116 to rotate
the cutter and pull or aspirate tissue debris in a proximal
direction. The clearance between the catheter body 120 and
conveying member 118, as well as the pitch and thread depth of the
conveying member 118, may be chosen to provide the desired pumping
effectiveness, as will be described in greater detail later.
[0125] As seen in FIG. 2A, the ferrule 116 can have a distal
bearing surface to bear against the proximal surface of the cutter
108 and keeps the cutter axially stable in the housing 104. In
cases where the housing is stationary, the ferrule 116 can be
rigidly bonded/linked to the housing 104 using solder, brazing,
welding, adhesives (epoxy), swaging, crimped, press-fit, screwed
on, snap-locked or otherwise affixed. As shown, the ferrule 116 can
have holes or other rough features that allow for joining with the
catheter body 120. While adhesives and heat fusing may be employed
in the construction, such features are not required. Often
adhesives are unreliable for a small surface contact and heat
fusing can cause the catheter body 120 to degrade.
[0126] The use of a mechanical locking ring 126 allows the cutting
assembly 102 to be short. Such a feature is important for
maximizing the flexibility of the distal section 122 of the
catheter 120 as it is required to navigate tortuousity in blood
vessels. In one variation, a ring or band 126 can be swaged onto
the catheter body 120 and over the ferrule 116. This drives
portions of the ring/band as well as the catheter body into the
openings of the ferrule 116 allowing for increased strength between
the cutter assembly 102 and catheter body 120.
[0127] FIGS. 5A and 5B show a respective perspective view and
cross-sectional side view of another variation of an open ended
cutter housing 104. As shown, the cutter housing 104 includes an
opening 107 located on a front face of a cylindrical housing 104.
In this variation, the front edge 113 of the housing 104 can
function as a front or forward cutting surface and has a beveled
surface 177 on an inside surface of the housing 104. Such a beveled
feature reduces the risk of the cutting surface 113 from driving
into the wall of a vessel. As shown, some variations of the cutter
housing 104 include a bearing surface 178 located within the
housing 104. In an additional variation, to control the degree to
which the cutting assembly 102 removes tissue, the distal end or
cutting surface 177 of the housing 104 can be scalloped or
serrated. For example, instead of being uniform, the cutting
surface 177 can vary along a circumference of the housing in an
axial direction (e.g., the serrated edges of the cutter extend
along an axial length of the housing).
[0128] Additional variations of an open ended cutter assembly 102
comprise a spinning turbine-like coring cutter 172 is shown in
FIGS. 6A and 6B. FIG. 6B shows a side view of the coring cutter
102. In use, the coring cutter can be hydraulically pushed to drive
the sharp edge through tissue. The turbine like cutters 172 have
helical blades 174 on the inside of the sharp cylinder housing
176.
[0129] An element of the coring cutter 102 may also have spokes or
centering devices 184 as shown in FIGS. 7A to 7F to center the
housing 104 about the guidewire. Optionally, the centering devices
184 may comprise an element of the guidewire 128, as shown. This
helps to keep the cut of the plaque centered about the vessel wall
for safety. The spokes 184 also act as an impeller to pull stenotic
tissue back and this helps to drive the cutter forward as well as
achieve aspiration to minimize embolization.
[0130] 2. Guarded Housing Cutter Assemblies
[0131] a. Cutting Edge Configurations
[0132] FIG. 8A shows a variation of a tissue removal or debulking
system 100 where the cutter assembly 102 is within a guarded
housing 104. In this variation, the cutter assembly contains a
first set of cutting edges 112 and a second set of cutting edges
109, where the first cutting edges 112 may extend along the entire
length of the cutting assembly 102 (i.e., the entire length that is
exposed in the openings 106 of the housing 104). In contrast, the
second set of cutting edges 109 (in the figure only one such second
cutting edge is visible) extend only along a portion. However,
variations of the devices, systems, and methods described herein
can include any number of cutter configurations as described herein
or as known by those skilled in the art. Furthermore, although the
illustrated system 100 shows a plurality of openings 106 in the
housing 104, alternative cutting assemblies 102 can include a
housing having a single opening on a distal face, as previously
described.
[0133] FIG. 8B shows a variation of the cutting edges comprising a
first set of cutting edges 112 that extend along (or substantially
along) the cutter 108 and a second cutting edge 109 that extends
only along a portion of the cutter 108. Although the number of
cutting edges can vary, typically the cutting edges will be
symmetric about an axis 111 of the cutter 108. For example, in one
variation, the illustrated cutter 108 will have a pair of second
cutting edges 109 symmetrically located about the cutter 108 and a
pair of first cutting edges 112 symmetrically located about the
axis 111 of the cutter 108. Accordingly, such a construction
results in two cutting edges 112 located on a distal portion of the
cutter 108 and four cutting edges 109 and 112 located on a proximal
portion of the cutter 108.
[0134] Providing a cutter 108 with fewer cutting edges on a distal
cutting portion and an increased number of cutting edges on a
proximal cutting portion allows for a more aggressive cutting
device. As shown, the cutter 108 can be configured with cutting
edges 109, 112 that are adjacent to grooves, channels, or flutes
110 (where the combination is referred to as a "cutting flute").
The cutting flute 110 provides a path for the cut material to
egress from the treatment site through the system 100, and improves
the impelling force generated by the cutter 108. The helical flutes
110 and sharp cutting edges 112 may be parallel to each other and
may be wound from proximal to distal in the same sense as the
rotation of the cutter. When the cutter 108 rotates, it becomes an
impeller causing tissue debris to move proximally for
evacuation.
[0135] By reducing the number of flutes on the distal portion of
the cutter, the flutes can be made deeper. The deeper flutes allow
the cutting edge adjacent to the flute to remove greater amounts of
material. However, increasing the size of the material can also
increase the chances that the material becomes stuck or moves
slowly through the catheter 120 during removal. To alleviate this
potential problem and increase the efficiency of transporting the
material through the catheter, the cutter can be configured with an
increased number of cutting edges towards a rear of the cutter that
reduce the size of the cut material by providing a second cut of
the material to further reduce the material size for improved
transportation.
[0136] By controlling the number of cutting edges 109, 112 that are
exposed through openings 106 in the housing 104, it is possible to
control the relative amount of cutting engagement (both length of
cutting and depth of cut, together which control the volume of
material removed per unit rotation of the cutter). These features
allow independent control of the maximum torque load imposed on the
system 100. By carefully selecting the geometry of the flutes and
or cutting edges 112 relative to the openings 106 in the housing
104, it is possible to further control the balance of torque. For
example, the torque load imposed on the system is caused by the
shearing of tissue when the cutter edge 112 and/or 109 is exposed
by passing through the housing window 106. If all cutter edges
simultaneously shear, as for example when the number of housing
windows is an even multiple of cutter edges, the torque varies
cyclically with rotation of the cutter. By adjusting the number of
cutters and windows so one is not an even multiple of the other
(for example, by using five windows 106 on the housing and four
cutting edges on the cutter 108), it is possible to have a more
uniform torque (tissue removal from shearing action) during each
rotational cycle of the cutter 108. It is to be appreciated that
the cutting edge configurations described above are available for
all cutter assembly embodiments described herein.
[0137] The geometry of the cutter 108 and housing 104 can be used
to tailor the desired degree of cutting. The housing 104 and
orientation of the openings 106 can be used to limit the depth of
cutting by the cutter 108. In addition, the distal end of the
housing 104 may be domed shaped while the proximal end may have a
cylindrical or other shape. For example, by creating larger
apertures or windows 106 in the housing, a larger portion of cutter
108 may be exposed and the rate of cutting increased (for a given
rotation speed). By placing the cutting window 106 on a convex
portion or side wall 105 of the housing 104, the debulking
effectiveness is much less sensitive to the alignment of the cutter
housing 104 to the lesion, than if the window 106 were on the
cylindrical portion of the housing. This is a key performance
limitation of traditional directional atherectomy catheters. In
addition, placement of the window 106 on the convex portion of the
housing creates a secant effect (as described below).
[0138] b. Cutter Assembly Configurations
[0139] FIG. 9 illustrates an exploded view of a cutter assembly 102
and ferrule 116. In this variation, the cutter assembly 102
includes a housing 104 having three openings 106 symmetrically
placed about a sidewall 105 of the housing. FIG. 9 also shows an
embodiment of cutter 108 that comprises a distal portion 90 mounted
on a proximal portion 92 (where the proximal cutter portion 92 can
also be referred to as a cutter core adapter). The proximal cutter
portion 92 contains a shaft 94 terminating in a mating piece 140
for coupling the cutter 108 to the housing 104 (where the mating
piece 140 nests within a center lumen 142 in a front face of the
housing 104. The cutter 108 can also include a passage 130 for
passing of a guidewire through the system 100.
[0140] Although the inventive system 100 includes embodiments of
cutters formed from in a unitary body, providing the cutter 108
with distal and proximal 90, 92 cutter portions allows for optimal
selection of materials. In addition, as shown, a first cutting edge
112 can extend along both cutter portions 90, 92 while a secondary
cutting edge 109 may extend only along the proximal cutter portion
92. Given this configuration, when the cutter portions 90, 92 join
to form the cutter 108, the distal portion 90 of the cutter only
contains two fluted cutting edges while the proximal cutting
portion 92 includes four fluted cutting edges. Naturally, any
number of fluted cutting portions are within the scope of the
invention. However, variations include fewer cutting edges on a
distal end of the cutter 108 relative to the number of cutting
edges on a proximal end of the cutter 108. Moreover, the cutting
edges may or may not be symmetrically located about the cutter.
[0141] FIG. 10 shows the housing 104 having a distal nose with the
center lumen 142 for receiving the mating piece 140 of the cutter
108. Such features assist in centering the cutter 104
concentrically inside the housing 104. As described below,
variations of the cutter assembly 102 include the addition of a
burr element for grinding hard tissue such as calcified plaque or a
dilator member for separating materials towards the openings
106.
[0142] FIGS. 11A through 15 show various additional examples of
cutting assemblies 102 including a guarded housing 104, and that
can be incorporated with the system 100.
[0143] FIG. 11A illustrates the cutting assembly shown in FIGS. 8A,
8B, and 9 where the openings 106 form helical slots in the housing
104. The openings 106 may or may not be aligned with the cutting
edges 109, 112 of the cutter 108. For aggressive cutting, the slots
106 and cutting edges 109, 112 can be aligned to maximize exposure
of the tissue to cutting edges. In other words, the cutting edges
109, 112 and openings 106 can be in alignment so all cutting edges
109, 112 are exposed at the same time to allow simultaneous
cutting. Alternatively, alignment of the openings and edges 109,
112 may be configured so that fewer than all the cutting edges 109,
112 are exposed at the same time. For example, the alignment may be
such that when one cutting edge is exposed by an opening 106, the
remaining cutting edges are shielded within the housing 104.
Variations of such a configuration allow for any number of cutting
edges to be exposed at any given time. In addition, the variation
depicted in FIG. 11A shows a window or opening 106 large enough to
expose both the first 112 and second 109 cutting edges. However, in
alternate variations, the windows can be configured to only expose
the cutting edges 112 on the distal end of the cutter 108.
[0144] In another variation adapted to even out the torque profile
of the device when cutting, the cutter 108 can be configured such
that the number edges/cutting surfaces 109, 112 of the flutes 110
that are aligned with the housing openings 106 does not vary
throughout the rotational cycle. This prevents the catheter from
being overloaded with torque spikes and cyclic torque variations
due to multiple cutting edges/flutes engaging with tissue in
synchrony. In other words, the length of the cutting surface 112
exposed through the openings 106 of the housing 104 remains the
same or constant.
[0145] In the variation shown in FIG. 11B, the cutting edges 109,
112 are configured to capture debris within the flute 110 as the
cutter 108 rotates. Typically, the cutter 108 may be designed with
a secant effect. This effect allows for a positive tissue
engagement by the cutter 108. As the cutter 108 rotates through the
opening, the cutting edge moves through an arc where at the peak of
the arc the cutting edge protrudes slightly above a plane of the
opening 106. The amount of positive tissue engagement can be
controlled through selection of the protrusion distance through
appropriate design of the housing geometry (for example, by a
combination of location and size of the window 106 and radius of
curvature of the housing 104). The cutting edge 109 or 112 can
extend out of the housing 104 through the window 106 as it rotates.
This structure can also be designed to drive or impel the debris to
the conveying member 118 (see FIG. 2A). In this case, the flutes
110 within the cutter 108 are helically slotted to remain in fluid
communication with the conveying member 118.
[0146] FIGS. 11A and 11B also show a surface of the cutter 108
having a curved-in profile distally and is close to the housing 104
surface. Note that housing openings 106 with this curved profile
allows the cutting edge 112 to protrude beyond the housing's outer
surface. In other words, the openings 106 form a secant on the
curved surface of the housing 104. Such a feature allows improved
cutting of harder/stiffer material like calcified or stiff fibrous
tissue where such tissue does not protrude into the housing
104.
[0147] As shown in FIG. 11C, variations of the cutter 108 may have
cutting edges 109, 112 with positive rake angles .alpha.- i.e., the
cutting edge is pointed in the same direction as that of the cutter
rotation. This configuration maximizes the effectiveness of the
impelling and cutting action (by biting into tissue and avoiding
tissue deflection).
[0148] FIG. 12 shows a variation of a cutter assembly 102 where a
housing 104 of the cutter assembly 102 includes a conical, tapered,
or dilator extension 133 extending from a front face of the housing
104. The dilator extension 133 is adapted to serve a number of
purposes, namely that it can help prevent the cutting assembly 102
from damaging a vessel wall. In addition, the added structural
reinforcement of the front face of the housing 104 reduces the
chance that the rotating cutter 108 actually cuts through the
housing 104 if the struts were to deflect inward. However, one
important feature of the dilator extension 133 is that it provides
a tapered surface from a guidewire to the openings 106 in the
housing 104. Accordingly, as the dilator extension 133 advances
through occlusive material, the dilator extension 133 forces or
dilates material away from a guidewire towards the openings 106 and
cutting edges. In order to dilate material away from a center of
the cutter assembly 102, the dilator extension 133 must have
sufficient radial strength. In one example, the dilator extension
133 and housing 104 can be fabricated from a single piece of
material as discussed herein.
[0149] The dilator extension 133 typically includes an opening 130
for passage of a guidewire. In addition, in most variations, a
front end 135 of the dilator extension 133 will be rounded to
assist in moving the occlusive material over a surface of the
dilator 133. Furthermore, the surface of the dilator extension 133
can be smooth to permit sweeping of the cutting assembly 102 as
discussed below. Alternatively, the dilator extension 133 can have
a number of longitudinal grooves to direct material into the
openings 106. In additional variations, the dilator extension 133
may not include an opening 130. In such a case, the dilator
extension 133 may fully taper to a closed tip.
[0150] FIGS. 13A to 13C show use of a system 100 incorporating a
dilating member 133. In this variation, the device 100 is advanced
over a guidewire 128. However, use of a guidewire 128 is optional.
As the device 100 approaches the plaque or occlusive material 4,
the dilating member 133 forces the plaque 4 away from a center of
the system 100 and towards openings 106 in the cutting assembly 102
as shown in FIG. 13B. Clearly, the dilating member 133 must have
sufficiently radial strength so that it forces the obstruction
towards the openings 106. However, in those variations where the
dilating member 133 is conical or tapered, the plaque material 4 is
gradually moved towards the openings 106. In those devices not
having a dilating member 133, the physician must apply excessive
force to move the cutter against the plaque 4. In some excessive
cases not incorporating a dilating member 133, the cutter may be
able to shear through a cutter housing leading to failure of the
device.
[0151] FIG. 13C illustrates a situation where the system 100
traverses the entire occlusion 4. However, as described in detail
later, the device may be configured for sweeping within the vessel.
As such, the physician may choose to sweep the system 100 within
the occlusion to open the occlusion during traversal of the
occlusion or after a path is created through the occlusion. In
either case, the nature of the dilation member 133 also functions
to keep the cutting assembly 102 spaced apart from a wall of the
vessel 2.
[0152] FIGS. 14A and 14B show another variation of a cutter
assembly 102 having a forward cutting surface 113 on a distal
portion of the cutter 108. In this variation, the cutter housing
104 may include two or more large openings 106 that allow the
forward cutting surface 113 to engage tissue when moved in a distal
direction. The cutter 108 may also include a plurality of fluted
cutting edges 112.
[0153] As shown in FIG. 15, a cutter assembly 102 can also have a
burr 180 protruding from its distal portion. Although the burr 180
may have any type of abrasive surface, in one variation, this burr
180 is blunt and has fine grit (such as diamond grit) to allow for
grinding of heavily calcified tissue without injuring adjacent soft
tissue. This combination of a burr 180 and cutter 108 allow the
cutter assembly 102 to remove hard stenotic tissue (e.g., calcified
plaque) using the burr 180 while the sharp-edged shaving cutter 108
removes softer tissue such as fibrous, fatty tissue, smooth muscle
proliferation, or thrombus. In variations, the burr 180 can also
have helical flutes to help with aspiration, or the burr can be
incorporated into a portion of the cutting edge (for example, the
most distal aspect of the cutter 108).
[0154] c. Distal and Proximal Cutting
[0155] FIGS. 16A and 16B show an additional variation of a cutting
assembly 102 adapted for use with the system 100. FIG. 16B shows a
side view of the cutter assembly 102 of FIG. 16A. In this
embodiment, the cutting assembly 102 includes larger windows 106 to
accommodate a cutter 108 that includes a plurality of directional
cutting surfaces 112, 113, and 115. As the cutter 108 rotates
within the housing 104, the fluted cutting edge 112 cuts in a
direction that is tangential to a rotational direction of the
cutter 108. In other words, the fluted cutting edges 112 cut
material that is about the perimeter of the cutter 108 as it spins.
The cutter 108 also includes on or more forward and rearward
cutting surfaces 113, 115. These cutting surfaces 113, 115 engage
tissue when the catheter is run in a forward direction or rearward
direction. The ability to engage and remove tissue in multiple
directions have been shown to be important for effective debulking.
However, a variation of a cutter 108 in the present invention can
include a cutter 108 with one or two directional cutting surfaces.
For example, the fluted cutting edges 112 can be combined with
either the forward 113 or rearward 115 cutting surfaces. The
ability to debulk in a forward, rearward, and rotational directions
also reduces the chance that the cutter assembly deflects from
stubborn or hard tissue.
[0156] B. The Catheter Assembly
[0157] 1. Catheter Body
[0158] FIG. 17 shows the distal portion 122 of the atherectomy
system 100 having a cutter assembly 102 extending from the catheter
body 120. As will be discussed below, the catheter body 120 can be
coupled to a rotating mechanism or motor 150, desirably in the
handle 200, which ultimately drives the cutter assembly 102 via a
torque shaft 114.
[0159] In general, for proper debulking of tissue within vessels,
the system 100 desirably includes a catheter 120 that is able to
support the cutter assembly 102 with sufficient apposition force
(bending stiffness). The catheter body 120 should be torqueable
enough (i.e., have sufficient torsional stiffness) so that the
physician can point the cutter assembly 102 to the desired angular
position within the vessel 2. The system 100 should also be
pushable enough (i.e., have sufficient column stiffness) to allow
proper cutting as the physician advances the device through tissue.
However, these needs must be balanced against making a device that
is too stiff to reliably access tortuous or angled anatomy. In
order to balance these requirements, a variation of the system 100
can have a more flexible distal tip location 122 (e.g., within the
last 10 cm as a non-limiting example) to improve the navigation
(including trackability over a guidewire, for example) in tortuous
anatomy. Because the overall stiffness (in compression and torque)
depends upon the full length of the catheter 120, but navigation is
influenced mainly by the distal tip region 122, this method is one
way to optimize several variables at the same time.
[0160] An additional design for increased torque and push is to
construct the catheter body 120 and/or sweep member 270 (to be
discussed in greater detail below) from a braid over a wound coil,
with an optional polymeric jacket covering. This composite
construction may be over a polymer liner made of a material such as
PTFE. Yet another variation includes a catheter body 120 and/or
sweep member fabricated from a metal tube having selective cuts
along the length of the tube (e.g., stainless steel or nitinol) to
create the desired profile of stiffness (bending, torsion, and
compression) along the length of the catheter 120. This slotted
metal tube can be lined or jacketed with polymeric material, and
further may be treated to produce hydrophilic, hydrophobic, or drug
binding (heparin, antimicrobial) properties. The configurations
described herein apply to any debulking device described
herein.
[0161] The catheter body 120 may also be composed of a reinforced
sheath, such as a metal braid sandwiched in a polymeric matrix of
such materials as high density polyethylene (HDPE), polyethylene
(PE), fluoro-polymer (PTFE), nylon, polyether-block amide (PEBAX),
polyurethane, and/or silicone. The sheath is stiffer proximally
than distally. This can be achieved by using softer grades of
polymers distally and/or having no metal braid distally.
[0162] FIGS. 18A through 18F illustrate possible variations of a
composite construction that can be employed in fabricating either a
catheter body 120 and/or a sweep member 270 for use in the
debulking systems described herein. FIG. 18A shows a composite
construction 290 of a slotted tube 292, where the tube can be
selected from e.g., a polymer, a metal--such as stainless steel, or
a shape memory alloy--such as a super-elastic Nitinol tube, or a
combination therein. The pattern of slots along the tube 292 can be
tailored to achieve the desired properties such as graded stiffness
along the long axis and/or the short axis of the catheter body 120.
The construction 290 can optionally include polymeric coatings,
sleeves, or liners 298 in the inner and/or outer surfaces of the
tube 292.
[0163] FIG. 18A also shows a tube 292 as having a first region 294
and a second region 296 where the frequency of the slots varies
between regions. Any number of slotted tube configurations, such as
those found in medical devices designed for navigation to tortuous
areas, can be employed in the designs herein. Such designs, when
combined in atherectomy--debulking catheters with sweep frames as
described herein, provide significant and unexpected improvements
in steering and cutting of lesions.
[0164] FIG. 18B illustrates another variation of a composite
construction 300 that can be employed in a catheter body 120 and/or
a sweep member 270 for use with variations of the debulking systems
100 described herein. As illustrated, the construction 300 includes
a coil member 302 covered by a braid 304. The coil and braid can
each be fabricated from any material commonly known in the field of
braided/coiled catheters. For example, the coil 302 can be wound
from a super-elastic wire or ribbon. While the braid can comprise a
plurality of super elastic or stainless steel filaments braided or
woven together. FIG. 18B also shows the braid 304 covered by a
polymeric coating, sleeve, or liner 306.
[0165] In an additional variation, the catheter body 120 and/or
sweep member 270 can comprise a spiral cut tube covered by a liner
or polymeric layer. In such a case, the angle of the spiral as well
as the width can be selected to impart desired characteristics on
the device. For example, the spiral can be selected to maximize
pushability of the device while maintaining a near one-to-one
relationship between the cutting assembly 102 and proximal end of
the device when rotating or sweeping the cutting assembly.
[0166] FIG. 18C shows yet another variation of a catheter body 120
and/or a sweep member 270 for use with variations of the debulking
systems 100 described herein. As can be seen, the catheter body 120
may include a multi-body design having minimal torsional losses
while maximizing bending in a first portion 120A and longitudinal
stiffness in a second portion 120B. The first portion 120A is shown
having a dovetail construction adapted for predefined expansion
between the dovetail features, providing for controlled
flexibility. The second portion 120B is shown having a helical cut
pattern creating a line-to-line fit of supports, which creates a
helical series of uninterrupted material to maintain bending-free
transmission of torsional tensile and compressive loads. This
embodiment may also include an elastic outer or inner sheath or
jacket 125 adapted to elastically constrain the dovetailed
components from axially expanding, but allowing the distal portion
120A to radially flex.
[0167] FIGS. 18D and 18E show detailed views of embodiments of the
first and second portions 120A and 120B, showing optional
configurations of a dovetail feature, with FIG. 18D showing a
traditional dovetail construction, and FIG. 18E showing a
serpentine configuration. It is to be appreciated that other
configurations are also possible. FIG. 18F shows the catheter body
120 in a radially flexed position, showing the bending of the first
portion 120A through the arced expansion of the dovetailed
configuration.
[0168] Coatings can be applied to the moving components in the
catheter 120 to reduce friction. In one embodiment, the catheter
120 and the torque shaft 114 are coated with a hydrophilic coating
(polyvinyl alcohol) to reduce friction between the moving
components in the catheter 120. The coatings can also be
hydrophobic (e.g. parylene, PTFE). The coatings can be impregnated
with heparin to reduce blood clotting on surface during use.
[0169] 2. Torque Shaft and Conveyer Member
[0170] FIG. 19A illustrates a partial cross-sectional view of a
variation of the distal portion 122 of the system 100 showing the
placement of the torque shaft 114 within the catheter body 120 and
sweep frame 250. As shown, this variation of the system 100
includes a conveyor member 118 located within the catheter body 120
and on an exterior surface of the torque shaft 114. The conveyor
member 118 may be an auger type system or an Archimedes-type screw
that conveys the debris and material generated during the procedure
away from the operative site. In any case, the conveying member 118
may have a raised surface or blade that drives materials in a
proximal direction away from the operative site (see FIG. 19B).
Such materials may be conveyed to a receptacle outside of the body
or such materials may be stored within the system 100. The torque
shaft 114 and conveying member 118 may extend along the full length
of the catheter and possibly into the handle 200, or the conveying
member may extend only along a portion of the length of the
catheter 120. As shown, the torque shaft 114 and conveyor 118 fit
within the sweep frame 250. In some variations of the system 100, a
cover or film can be placed between the sweep frame 250 and torque
shaft 114 to prevent debris from becoming trapped within the
serrations, slots or openings 252 of the sweep frame 250. The cover
or film may also act as a smooth, low friction surface.
[0171] FIG. 19C shows a partial sectional view of an alternative
example of a torque shaft 114 for coupling to a cutter assembly
102. To aid in removal of materials, the torque shaft 114 may be a
set of counter-wound coils, with the outer coil wound at the proper
(greater) pitch to form the conveying member 118. Winding the coils
counter to each other automatically reinforces the torque shaft 114
during rotation. Alternatively, the torque shaft 114 may be made
out of a rigid material such as plastic, rendered flexible by
incorporation of a spiral relief or groove which acts as a
conveying member 118. Although the shaft 114 may be fabricated from
any standard material, variations of the torque shaft may include a
metal braid and/or one or more metal coils embedded in a polymer,
such as PEBAX, polyurethane, polyethylene, fluoropolymers,
parylene, polyimide, PEEK, and PET, as non-limiting examples. These
constructions maximize torsional strength and stiffness, as well as
column strength for "pushability", and minimize bending stiffness
for flexibility. Such features are important for navigation of the
catheter through tortuous vessels but allow for smooth transmission
of torque over the long length of the catheter.
[0172] In the multi-coil construction, the inner coil should be
wound in the same sense as that of the rotation so that it would
tend to open up under torque resistance. This ensures that the
guidewire lumen 130 remain patent during rotation. The outer coil
(conveying member) 118 should be wound opposite the inner to
counter the expansion to keep the inner coil from binding up
against the catheter tube 120.
[0173] Typically the guidewire lumen 130 will be used to deliver a
guidewire. In such cases, the central lumen 130 may be coated with
a lubricious material (such as a hydrophilic coating or Parylene,
for example) or made of a lubricious material such as PTFE to avoid
binding with the guidewire. However, in some variations, a
guidewire section is affixed to the outer distal portion 122 of the
catheter body 120, or to the cutter assembly housing 104 (i.e.,
rapid exchange, to be described later). Moreover, the central lumen
130 of the torque shaft 114 may also be used to deliver fluids to
the operative site simultaneously with the guidewire or in place of
the guidewire.
[0174] In some variations, the conveying member 118 may be integral
to the shaft 114 (such as by cutting the conveying member 118 into
the torque shaft 114 or by extruding the torque shaft 114 directly
with a helical groove or protrusion. In an additional variation as
shown in FIG. 19D, an additional conveying member 118' may be
incorporated on an inside of the torque shaft 114, where the
internal conveying member 118' is wound opposite to that of the
external conveying member 118. Such a configuration allows for
aspiration and debris (via the external conveying member 118) and
infusion (via the internal conveying member 118'), or vise-versa.
Such a dual action can enhance the ability to excise and aspirate
plaque by: (1) thinning the blood, whether by viscosity alone or
with the addition of anti-coagulants such as heparin or warfarin
(cumadin), and/or anti-platetlet drugs such as Clopidogrel, (2)
improving the pumpability (aspirability) of the excised plaque by
converting it into a solid-liquid slurry that exhibits greater
pumping efficiency, and/or (3) establishing a flow-controlled
secondary method of trapping emboli that are not sheared directly
into the housing, by establishing a local recirculation zone.
[0175] As noted above, the conveying member 118 can be wound in the
same directional sense as the cutter 108 and in the same direction
of rotation to effect aspiration of tissue debris. The impeller
action of the cutter 108 moves the tissue debris from inside the
housing 104 opening(s) 106, 107, past the cutting edge(s) 112 and
109 to further grind the debris, and into the torque shaft 114. The
pitch of the cutting edges 112 may be matched to that of the
conveying member 118 to further optimize aspiration. Alternatively,
the pitch of the conveying member 118 may be changed to increase
the speed at which material moves once it enters the conveying
member 118. As discussed herein, debris can be evacuated outside
the body by the conveying member 118 action along a portion or the
full length of the catheter body 120 and with or without supplement
of a vacuum pump 152 connected to the catheter handle 200.
Alternatively, the debris may be accumulated in a reservoir within
or attached to the system 100.
[0176] It may be advantageous to rotatably couple the torque shaft
114 to a drive unit 150 electromagnetically, without physical
contact. For example, the torque shaft 114 can have magnetic poles
installed at the proximal end, within a tubular structure that is
attached to a sheath around the torque shaft. The stationary
portion of the motor 150 can be built into the handle 200 that
surrounds the tubular structure. This would allow the continuous
aspiration through the catheter body 120 without the use of high
speed rotating seals.
[0177] 3. Sweep Frame
[0178] FIGS. 20A through 20C further illustrates one embodiment of
a sweep frame 250 located within the catheter body 120. The sweep
frame 250 may be adapted to permit an axial length L of the distal
portion 122 of the catheter 120 to bend or articulate in response
to a force typically applied at a proximal portion of the catheter
or at the handle 200 of the system 100. The applied force may be
provided in a variety of manners, such as distally directed,
proximally directed, and/or rotational, or any combination.
[0179] In the illustrated embodiment, the sweep frame 250 comprises
a tube structure having a plurality of serrations, slots, or
semi-circumferential openings 252. Overall, the area having the
openings 252 on the sweep frame 250 weaken the frame 250 by
providing a section of reduced column strength on a first radial
side 254 of the sweep frame (i.e., the sides containing the
openings). The portion 256 of the sweep frame 250 that is not
weakened maintains a column strength that is greater than that of
the first radial side 254 of the sweep frame 250. This
constructions permits deflection of the distal portion 122 of the
system 100 when an axial force 264 is applied to the sweep frame
250 driving it against a fixed section (e.g., the cutter assembly
102, and/or a portion of the catheter body 120). In an alternative
embodiment, an axial force may be applied to the catheter 120 or
torque shaft 114, for example, the force driving a fixed section
(e.g., the cutter assembly 102) against the sweep frame 250 and
causing deflection of the distal portion. As shown in FIG. 20C,
this axial force compresses the sweep frame 250 causing the area
with the weakened column strength to compress (i.e., the sides of
the sweep frame 250 adjacent to the openings 252 move towards one
another on the first radial side 254). This in turn causes the
deflection of the spine or strengthened side 256 in a direction
towards the first radial side 254. Because the sweep frame 250 may
be coupled to the catheter (e.g., it may be fully or partially
encapsulated within the catheter body 120), the deflection of the
sweep frame 250 causes deflection 262 of the distal end 122 of the
catheter body 120 and cutter assembly 102 in a direction towards
the first radial side 254 causing an axis of the cutter assembly
102 to form an angle A with an axis of the proximal portion 258 of
the sweep frame 250.
[0180] The sweep frame 250 is rotatable independently of the
rotatable cutter 108 and torque shaft 114. In certain variations,
the sweep frame 250 is independently rotatable from the catheter
body 120 as well. In such configurations, as the deflected sweep
frame 250 rotates, the cutting assembly and/or distal catheter
portion 122 move in an arcuate path relative to an axis 260 of a
proximal end 258 of the sweep frame 250. The sweep frame 250 can
also be configured to rotate with the catheter body 120. In this
latter configuration, the cutter assembly 102 can also rotate with
the sweep frame 250 while the rotatable cutter 108 still is able to
rotate independently of the sweep frame 250.
[0181] FIGS. 21A through 21C illustrate additional variations of
sweep frames 250 for use with the cutting assemblies 102 and
catheters 120 described herein. For purposes of highlighting the
sweep frame 250, the torque shaft 114 is omitted from FIGS. 21A to
21C. However, as shown in FIG. 17 for example, a torque shaft 114
may extend through the sweep frame 250 where the torque shaft and
sweep frame can rotate independently from one another.
[0182] FIG. 21A shows a distal view of a debulking system 100 where
the catheter body 120 is partially removed to show a variation of a
sweep frame 250. In this variation, the sweep frame 250 may be
constructed from a laser cut tube having serrations, openings, or
slots 252. The openings 252 create a weakened section along a first
radial side 254 of the sweep frame 250. The side opposite 256 to
the first radial side 254 comprises an area of increased column
strength. Accordingly, as a physician applies an axial force (e.g.,
in a distal direction) at the proximal end of the system 100,
typically via a sweep member 270, as discussed below, the axial
force causes the sweep frame 250 to compress against a fixed area
within the distal portion 122 of the catheter body 120 (see FIG.
20B). As the force compresses the sweep frame 250, the sweep frame
250 is forced to compress at the weakened section along the first
radial side 254 causing bending at the continuous area or spine 256
of the sweep frame 250 in the direction indicated by the arrow 262
(see FIG. 20C). The fixation area (the area against which the sweep
frame 250 encounters resistance) can be the cutter assembly 102 or
a distal area on the catheter body 120. However, any area will
suffice so long as the sweep frame 250 is able to bend upon the
application of a force.
[0183] The spacing and size of the openings 252 can be selected to
allow a pre-determined bend upon deformation of the sweep frame
250. For example, the openings 252 can be selected to limit
deflection of the distal portion 122 of the catheter to plus or
minus 90 degrees or to any angular bend to provide an added safety
measure when the system 100 is used within a vessel. Moreover, the
spacing between adjacent openings 252 and/or the size of openings
can vary in the sweep frame 250. For example, the spacing and/or
size of the openings 252 can increase or decrease along the length
of the sweep frame 250. In an additional variation, the spacing and
the size of the openings can vary inversely along the length of the
sweep frame 250.
[0184] In the illustrated variation, the size of the openings 252
in the sweep frame 250 may increase in a direction away from the
first radial side 254 of the sweep frame 250. This configuration
was found to minimize interference with the torque shaft (not
shown).
[0185] In addition, the sweep frames 250 described herein can have
any number of features to assist in joining the sweep frame 250 to
the catheter 120. For example, in those cases where the sweep frame
250 is constructed from a super-elastic or shape memory alloy, the
frame 250 can include one or more openings 253 located in a
sidewall to increase the bond between the superelastic/shape memory
alloy component and a regular metallic shaft.
[0186] 4. Sweep Member
[0187] FIG. 20C illustrates the tissue debulking system 100 upon
the application of force indicated in the direction of arrow 264.
As noted above, force 264 may be applied by the physician at the
proximal end or handle 200 of the system 100. In some variations,
the force may be applied through the use of a sweep member 270 that
is axially moveable within the catheter body 120. The sweep member
270 can comprise a tubular structure or a spline or wire that has
sufficient column strength to compress as well as rotate the sweep
frame 250. Because the distal end of the sweep frame is prevented
from moving distally (typically because the cutter assembly 102 is
affixed to the catheter body 120), the sweep frame bends at the
spine 256 in the direction of the first radial side 254. As shown,
the spacing between the openings 252 may simply decrease starting
at the first radial side 254 and extending to the spine 256. This
causes articulation of the cutting assembly 102 so that an axis 111
of the cutting assembly becomes offset from an axis of the proximal
end 258 of the sweep frame 250 as denoted by angle A. As noted
herein, the angle A is not limited to that shown. Instead, the
angle can be predetermined, depending on the construction of a
particular sweep frame 250 to provide any angle that is suited for
a target vessel or body lumen, and may range plus or minus 90
degrees or to any predetermined angular bend.
[0188] In one variation, the sweep member 270 (also called a sweep
shaft) may be fabricated as a hypo-tube structure (constructed from
a super-elastic alloy or a medical grade stainless steel, for
example). The sweep member 270 can have varying degrees of
flexibility to allow the catheter 120 to be more flexible at a
distal portion and rigid at a proximal portion. This allows for
improved navigation through tortuous anatomy as well as improved
transmission of torque generated at the proximal end of the device.
In additional variations, the sweep-member 270 should not be prone
to excessive compression or elongation given that it must transmit
the rotational force to the sweep frame 250.
[0189] Upon articulation of the cutting assembly 102, the physician
can further rotate the sweep member 270 as shown by arrow 280.
Rotation of the sweep member 270 causes rotation of the sweep frame
250 when articulated causing movement of the cutting assembly 102
in an arc-type motion about an axis of the proximal end 258 of the
sweep frame 250. This movement causes the cutting assembly 102
having a flexible length L to move through an arc having a radius
denoted by 282. In some variations of the device, the sweep frame
250 and sweep member 270 can rotate independently of the catheter
body 120. However, allowing the catheter body 120 to rotate with
the sweep frame 250 and sweep member 270 reduces the resistance on
the sweep member 270 as it rotates. In this latter case, the
catheter body 120, as well as the cutter housing 104, rotate with
the sweep frame 250. However, the rotatable cutter 108 (and the
torque shaft--not shown) still rotate independently of the sweep
frame 250.
[0190] Also as noted above, this ability to sweep the cutting
assembly 102 in an arc or a circle larger than a diameter of the
catheter 120 (or cutter assembly 102) allows the physician to
create a significantly larger opening in the target site than the
diameter of the cutting assembly 102 itself. Such a feature
eliminates the need to exchange the system 100 for a separate
cutting instrument having a larger cutting head. Not only does such
a feature save procedure time, but the system 100 is able to create
variable sized openings in body lumens.
[0191] FIG. 20C also illustrates a variation of the sweep member
270 that can be applied to any variation of the system 100 shown
herein. In some cases it may be desirable to disengage the sweep
member 270 from the sweep frame 250. In such a case, the sweep
member 270 can be axially slidable to disengage the sweep frame
250. However, upon re-engagement with the sweep frame 250, the
sweep member 270 must also be able to rotate the sweep frame 250.
Accordingly, the sweep frame 250 and sweep member 270 can include
one or more keys and key-ways. Although the illustration shows the
sweep frame 250 as having a keyway 266 at a proximal end 258 and
the sweep member 270 as having a key 272, any type of configuration
that allows translation of rotation is within the scope of this
disclosure.
[0192] FIG. 21A illustrates a variation of a system 100 having
sweep frame 250 with a weakened section 268 having a varying column
strength. In this variation, the column strength of the sweep frame
250 increases in a circumferential direction away from the first
radial side 254. The increase in column strength prevents radial
twisting of the sweep frame 250 as it deflects. In the illustrated
variation, the sweep frame 250 comprises a plurality of
reinforcement arms, ribs, or struts 274 within the openings 250 on
the sweep frame 250 where the arms, ribs, or struts 274 are
configured to preferentially bend towards the spine 256 as the
sweep frame 250 bends. In this variation, the portion containing
the arms, ribs, or struts 274 that is adjacent to (but spaced from)
the first radial side 254 comprises a second column strength that
is greater than the column strength of the radial side but less
than a column strength of the remaining spine 256. Again, the
varying column strength is intended to prevent twisting of the
sweep frame 250 upon deflection.
[0193] FIG. 21B shows another variation of a sweep frame 250. In
this variation, the sweep frame comprises a plurality of rings 276
spaced apart to create the openings 252 within the sweep frame 250.
The rings can be joined at the spine area 256 via a separate
member, a polymer coating, or a separate frame that is ultimately
joined to the rings 276. As noted above, the rings can be spaced or
vary in size to achieve the desired pre-determined curvature upon
compression of the sweep frame 250.
[0194] FIG. 21C shows another variation of a sweep frame 250
comprising a woven, coiled, braided or laser cut mesh structure
similar to that of a vascular stent. The sweep frame 250 structure
can comprise a wire or ribbon material having a reinforced section
to function as the spine 256. For example, one side of the stent
structure sweep frame 250 can be treated via a coating, fixture or
any other means to increase a column strength of the section.
Accordingly, this area of the stent structure sweep frame 250
functions as a spine 256 of the sweep frame 250. Although the spine
256 of FIGS. 21B and 21C are shown to be along a bottom portion of
the respective sweep frames, the sweep frames can be manufactured
to provide varying regions of column strength as described
above.
[0195] It is understood that the sweep frames can vary from those
that are shown to be any structure that allows for preferential
bending and rotation when placed within the catheter 120. The sweep
frame can be fabricated from a variety of materials including a
shape memory alloy, a super elastic alloy, a medical grade
stainless steel, or other polymeric material, as non-limiting
examples. The material of the sweep frame 250 can be radiopaque, or
can be altered to be radiopaque. In such cases, the physician will
be able to observe the degree of articulation of the device by
observing the curve of the sweep frame 250 prior to cutting
tissue.
[0196] 5. Steering and Sweeping
[0197] FIG. 22A illustrates an example of a variation of a
debulking system 100 being steered when using a sweep frame 250 and
sweep member 270 as described above. The ability to steer the
distal portion 122 and cutting assembly 102 of the system 100 is
useful under a number of conditions. For example, when debulking an
eccentric lesion in a tortuous vessel as shown, the cutting
assembly 102 should be pointed towards the side of the vessel 2
having the greater amount of stenotic material 4. Naturally, this
orientation helps prevent cutting into the bare wall/vessel 2 and
focuses the cutting on stenotic tissue 4. When in a curved section
of the vessel 2, without the ability to steer, the cutting assembly
102 would tend to bias towards the outside of the curve. As shown
in FIG. 22A, steering allows the cutting assembly 102 to point
inward to avoid accidental cutting of vessel wall 2.
[0198] The ability to steer the device 100 also allows for a
sweeping motion when cutting occlusive material. FIG. 22B shows the
rotation of the cutting assembly 102. As shown in FIG. 22C, when
the cutting assembly 102 deflects relative to the axis of the
catheter, rotation of the deflected portion 102 creates a sweeping
motion. It is noted that rotation or articulation of the cutting
assembly 102 also includes rotation or articulation of the catheter
to allow the cutting assembly to deflect relative to an axis of the
catheter.
[0199] FIG. 22D shows a front view taken along an axis of the
vessel to illustrate the sweeping motion causing the cutting
assembly 102 to sweep over a larger region than the diameter of the
cutting assembly 102. In most cases, when articulated, the cutting
assembly 102 may be rotated to sweep over an arc, a full circle, or
a controlled orbit of multiple circles.
[0200] A user of the system 100 may couple the sweeping motion of
the cutting assembly 102 with axial translation of the catheter 120
for efficient creation of a larger diameter opening over a length
of the occluded vessel. This is because the system 100 is adapted
to "sweep" the lumen of materials, the sweep feature allowing the
system 100 to create a passage (i.e., diameter) in the lumen having
a ratio ranging from about (one) to up to about 4 times the
diameter of the catheter 120, which equates to creating a passage
having a cross-sectional area of up to 16 times greater than the
cross-sectional area of the catheter 120. Prior concentrically
operating atherectomy systems are limited in their ability to clear
a lumen to their maximum area of cut.
[0201] By clearing a larger diameter passage than the diameter of
the debulking device, the system 100 creates a clinically relevant
increase in size of the lumen for blood flow. A clearing system
adapted to double the diameter of the lumen (compared to the
diameter of the catheter) is able to quadruple the area available
for blood flow. The system is adapted to debulk vessels ranging in
diameter from about 1 (one) mm to about 15 mm, although smaller and
larger diameter vessels are within the scope of the invention. In
addition, the system 100 is adapted to traverse the cutting
assembly across the inner width of the vessel, i.e., approximately
10 mm.
[0202] For example, using the formula (.pi.R.sup.2) for the area of
a circle, and using a catheter with a diameter of 2 mm, the area of
the catheter is (3.14.times.1.sup.2)=3.14 mm.sup.2. Now using a
cleared cross-sectional area having a diameter of 4 mm, the area of
the cleared lumen is (3.14.times.2.sup.2)=12.56 mm.sup.2, a factor
of four times the cross-sectional area of the catheter. Now using a
cleared cross-sectional area having a diameter of 8 mm, the area of
the cleared lumen is (3.14.times.4.sup.2)=50.24 mm.sup.2, a factor
of 16 times the cross-sectional area of the catheter.
[0203] As seen in FIG. 22E, the catheter 120 has a diameter D1. The
ability to steer and sweep allows the system to clear a lumen
having a cross-sectional diameter greater that the catheter 120,
including a diameter D2 (twice the diameter of the catheter), D3
(three times the diameter of the catheter), and D4 (four times the
diameter of the catheter).
[0204] The combination of movements described for steering and/or
sweeping may be performed when the device is placed over a
guidewire (although not necessary), for example by the use of a
lead screw in the proximal handle assembly 200 of the system. In
another aspect of the systems described herein, the angle of
articulation may be fixed so that the system 100 sweeps in a
uniform manner when rotated.
[0205] FIG. 22C also shows a variation of a debulking system 100
having a catheter body 120 where a first or distal portion 122 of
the catheter body rotates as identified by arrow 280 as the cutting
assembly 102 sweeps in an arc. The second portion 137 of the
catheter remains stationary. Accordingly, the two part catheter may
be joined to permit the relative movement between sections. The
distal portion 122 and/or the second portion 137 may incorporate a
sweep frame 250 and/or sweep member 270.
[0206] As described above, the catheter body 120 can remains
stationary while the inner sweep frame 250 and sweep member 270
rotate to move the cutting assembly 102 in an arc or orbit within
the lumen. Alternatively, the sweep frame 250 and sweep member 270
can rotate with the catheter body 120 but independently of the
cutting assembly 102 and torque shaft 114.
[0207] Again, the sweep member 270 can be composed of a
super-elastic alloy, a medical grade stainless steel, a metal braid
sandwiched in a polymeric matrix of such materials as polyethylene
(PE), fluoro-polymer (PTFE), nylon, and/or polyether-block amide
(PEBAX), polyurethane, and/or silicone, as non-limiting examples.
The sweep member 270 can also be made of counter wound metal coils.
Its distal end is curved and is preferably made of a material that
can withstand high degree of flex and retain its curved shape. Such
material may include polymers such as PE, nylon,
Polyetheretherketone (PEEK), Nickel Titanium (Nitinol), or spring
steel, as non-limiting examples.
[0208] As described above, selecting a desired profile for bending,
torsion and axial strength characteristics when designing the
catheter body 120 and/or sweep member 270 improves the overall
function of the debulking catheter system 100. Aside from the
improved ability to advance the cutting assembly 102 and sweep the
cutting assembly in an arc-type motion, the proper characteristics
improve the ability of the physician to steer the catheter 120. For
example, selection of the proper characteristics reduces the chance
that the distal portion 122 of the catheter 120 rotates more or
less than the proximal end or control knob 202 on the handle
200.
[0209] These characteristics along with the ability to steer the
catheter 120 provide a system 100 capable of both active and
passive steering. Active steering may incorporate both flexing the
distal portion 122 and rotating the distal portion to steer through
tortuous anatomy. As described below, this allows the physician to
advance the catheter 120 with or without a guidewire though
tortuous anatomy, and to direct the forward facing cutting assembly
102 to a side wall of a lumen to remove occlusive materials.
Passive steering may incorporate advancement of the catheter 120
until the cutting assembly 102 contacts a bend in the vessel, for
example. A simple rotation of the sweep frame 250 to adjust the
first radial side 254 of the sweep frame to the inside radius of
the bend (and the spine 256 to the outside radius of the bend)
allows the flexible distal portion to naturally or preferentially
bend with the vessel, and the catheter 120 may continue to be
advanced.
[0210] FIGS. 23A through 23H show an advancement of the catheter
120 through a tortuous vessel 2, and steering the cutting assembly
102 to a difficult to access treatment site at an inside corner of
a vessel bifurcation. FIGS. 23A and 23B show the catheter 120
advanced into the vessel 2 until a bend is contacted. As seen in
FIG. 23B, the spine 256 of the unflexed sweep frame 250 is shown on
the inside radius of the vessel bend.
[0211] FIGS. 23C and 23D show passive steering by simply rotating
the sweep frame 250 using the steering controls on the handle 200
to position the first radial side 254 of the sweep frame to the
inside radius of the bend. This rotation of the sweep frame allows
the distal portion to naturally bend with the vessel, and the
catheter 120 may continue to be advanced. FIGS. 23E and 23F show
the catheter 120 advanced to the next bend in the vessel 2, and the
passive steering process repeated to rotate the first radial side
of the sweep frame 250 to the inside radius of the bend, allowing
the flexible distal portion to naturally bend with the vessel.
[0212] FIGS. 23G and 23H show the catheter 120 being actively
steered to access an inside vessel wall to remove material 4. As
can be seen, the control knob 202 on the handle 200 may be both
advanced to deflect the distal portion of the catheter, and the
knob 202 may also be rotated to sweep the flexible distal portion
across the lesion 4 for debulking.
[0213] In another variation of the invention, the system 100 can
improve the ability of a physician attempting to navigate a
guidewire 128 through branching, tortuous or otherwise obstructed
anatomy. In the variation shown in FIG. 24A, as a physician
navigates a guidewire 128 through the anatomy, the tortuous nature
of the anatomy or obstructions 4 within the vessel 2 may prevent
advancement of the guidewire 128 as shown. In such a case, the
system 100 of the present invention permits a physician to withdraw
the guidewire within the catheter 120 or just distal to the cutting
assembly 102 (as shown in FIG. 24B). The system 100 can then be
advanced to a branching point or beyond the tortuous location or
obstruction, and articulated (as shown in FIG. 24C) so that the
physician can then advance the guidewire 128 beyond the
obstruction, sharp bend, or into the desired branch.
[0214] As previously described, the shape of the housing 104 as
well as the location of the window(s) 106, 107 can be chosen so
that when the cutting assembly 102 is substantially aligned with
the lesion, or engages it at less than some critical attack angle,
it will cut effectively. However, when pivoted at an angle greater
than the critical angle, the cutting edges or grinding element will
not engage the lesion, as shown in FIG. 24D. This means that at
large deflections, as the distal portion of the cutting assembly
102 approaches the vessel wall, it automatically reduces its depth
of cut and ultimately will not cut when the critical angle is
exceeded. For example, the cutter 108 distal tip is blunt and does
not cut. As the cutting assembly 102 is deflected outward, the
blunt tip contacts the vessel and keeps the cutting edges proximal
to the tip from contacting the vessel wall. In addition, the
guidewire in combination with the cutting assembly 102 can also act
as a buffer to prevent the cutting edges from reaching the vessel
wall. As shown, the portion of the guidewire that extends from the
housing 104 will bend at a minimum bend radius. This permits a
portion of the guidewire closest to the housing to act as a bumper
and prevents the cutter 108 and windows 106 from engaging the walls
of the vessel. In certain variations, guidewires with varying bend
radii can be selected to offer varying degrees of protection by
spacing the cutter 108 away from the tissue wall.
[0215] C. The Handle Assembly
[0216] FIG. 25A shows an exploded view of one embodiment of a
control handle 200 adapted to provide operational controls for the
system 100. As shown, the handle 200 may comprise a handle base
portion 201 and a catheter chassis portion 204, both of which may
snap or otherwise be coupled together to form the handle 200. Both
the handle base 201 and the catheter chassis 204 may be provided to
the user as a sterile, single use, and disposable device, along
with the catheter 120 and cutting assembly 102. The two component
handle 200 allows for improved manufacturability of the individual
components, i.e., the handle base 201 and the catheter chassis 204,
and for isolation of the power (e.g., power means 236) and rotating
means 150 from the catheter chassis 204. It is to be appreciated
that the handle 200 may be a single component handle, or may be
more than two components as well.
[0217] 1. Handle Base
[0218] As seen in FIGS. 25A and 25B, the handle base 201 comprises
an ergonomic grip and functionally convenient access to operational
controls of the system 100. A first base piece 246 and a second
base piece 248 may be coupled together to house elements including
on/off means 234, power means 236, rotational means 150, and a gear
206 coupled to the rotational means. The handle base 201 may be
composed of a polymeric matrix of such materials as polycarbonate,
acrylonitrile-butadiene-styrene (ABS), polymethyl methacrylate
(PMMA), polysulfone, polyethylene ptherethalate (PET), high density
polyethylene (HDPE), polyethylene (PE), nylon, polyether-block
amide (PEBAX), polyurethane, and/or silicone, as non-limiting
examples. As can be seen in FIG. 25B, coupling means 203, e.g.,
snap, clip, glue, weld, heat, and screw features, may be provided
on the handle base 201 and/or the catheter chassis 204, and allow
for tool free coupling between the handle base 201 and the catheter
chassis 204.
[0219] The on/off means 234 may provide a variety of control
options for control of the rotation of the cutter 108 including
on/off, ramp up and/or ramp down, and/or variable speed, as
non-limiting examples. The on/off means may be any of a variety of
known control mechanisms, including a slide switch, pushbutton,
and/or potentiometer, as non-limiting examples.
[0220] A power source 236 is desirably coupled to the on/off means
234 and the rotating means 150. The power source 236 may comprise a
variety of known power sources, such as a non-rechargeable battery,
a rechargeable battery, and a capacitor, as non-limiting examples.
Desirably, the power source 236 is adapted to maintain a consistent
supply of power to the rotating mechanism 150 through all operating
conditions, including no load through excessive torque and stall
conditions, without excessively draining the power source 236. The
power source may also have a predetermined amount of operational
power, e.g., sufficient power to operate the system 100
continuously during a procedure for about two to about three hours,
as a non-limiting example.
[0221] The rotating means 150, when powered on, provides rotation
to a gear 206. The gear 206 meshes with a catheter chassis drive
gear 207, which drives the torque shaft 114 (see FIG. 30). The
rotating mechanism 150 (e.g., an electric, pneumatic, fluid, gas,
or other rotational system), transmits the rotational energy to the
torque shaft 114, with the torque shaft 114 transmitting the
rotational energy to the cutter 108.
[0222] Variations of the system 100 may include use of a rotating
mechanism 150 located entirely within the handle 200, as shown. In
an alternative variation, the rotating mechanism 150 may be outside
the handle 200 and/or outside of the surgical field (i.e., in a
non-sterile zone) while a portion of the system (e.g., the torque
shaft 114) extends outside of the surgical field and couples to the
rotating mechanism 150.
[0223] The rotating mechanism 150 may be a motor drive unit. In one
working example, a motor drive unit operating at 4.5 volts and
capable of producing cutting speeds up to 25,000 RPM was used.
Another example of a motor drive unit included supplying the motor
at 6 volts nominal, running at about 12,000 RPM with higher torque.
This was accomplished by changing the gear ratio from 3:1 to
1:1.
[0224] In an alternative embodiment, the rotating mechanism 150 may
be powered by a controller that varies the speed and torque
supplied to the catheter 120 and torque shaft 114 to optimize
cutting efficiency or to automatically orbit the cutter 108 and/or
cutting assembly 102 using variable speed with a fixed flexible,
distal length of the catheter 120, or providing further orbiting
control by controlling the length of the distal flexible section
122 of the catheter 120). The length of the flexible distal portion
122 (or a predefined portion) may be controlled, i.e., adjusted by
including a member 124 either inside or outside the catheter 120,
or both inside and outside the catheter. The member 124 may
comprise an axially adjustable sheath, wire, or guidewire, for
example, the member 124 having a stiffness greater than the
flexible distal portion. As seen in FIG. 26A, when the sheath 124
is advanced distally, its added stiffness reduces the flexibility
of the flexible distal portion 122. When the sheath 124 is
retracted proximally, the length of the flexible distal portion may
be increased relative to the portion the sheath 124 was retracted
(see FIG. 26B).
[0225] Orbit control may be induced or enhanced by providing an
element of unbalance, i.e., an asymmetric cutter 108, housing 102,
or counterweight 123, for example (see FIG. 26C). As the torque
shaft 114 rotates the cutter 108, the asymmetric cutter (or
housing) causes the cutter assembly 102 to rotate in an arcuate
path, i.e., orbital path. The radius of this arcuate path may be
increased by increasing the length of the adjustable flexible
distal portion 122, and conversely, the arcuate rotational path may
be reduced by decreasing the length of the adjustable flexible
distal portion.
[0226] It is also possible to use feedback control to operate the
system 100 in a vessel safe mode, so that the rate of cutting is
decreased as the vessel wall is approached. This may be
accomplished through speed control, or by reducing the degree to
which the cutting blades penetrate above the housing window 106,
107 by retracting the cutter axially within the housing 104.
Feedback variables could be by optical (infrared) or ultrasound
transducer, or by other, transducers (e.g., pressure, electrical
impedance, etc.), or by monitoring rotational means 150
performance. Feedback variables may also be used in safety
algorithms to stop the cutter 108, for example, in a torque
overload situation.
[0227] 2. Catheter Chassis
[0228] As can be seen in FIG. 27, the catheter chassis 204 provides
an operational interface between the handle base 201 and the
functions of the catheter 120 and cutting assembly 102. The
catheter chassis 204 provides an extension of the catheter 120,
including a strain relief 234 positioned at a distal end of the
catheter chassis, and provides operational access to the catheter
120 for cutter assembly steering and sweeping (via the sweep
control knob 202, a spring plunger 226, and an indexing cassette
227), cutter rotation (via the catheter chassis gear 207 and torque
shaft 114), aspiration (via an aspiration port 229), irrigation
(via a flush port 129), and a guidewire (via a guidewire lumen
130). A male port and a female port may be provided to identify the
particular function. As can be seen in FIG. 27, coupling means 203
may also be also provided on the catheter chassis 204 to allow for
tool free coupling between the handle base 201 and the catheter
chassis 204.
[0229] a. Cutter Assembly Steering and Sweeping
[0230] FIGS. 27 through 28B show the sweep control knob 202, the
spring plunger 226, and the indexing cassette 227, the combination
of which allows for precise indexing (i.e., position control) of
the cutting assembly 102. As shown, the sweep member 270 and torque
shaft 114 extend through the sweep control knob 202 and the
indexing cassette 227. The sweep control knob 202 and the indexing
cassette 227 may be coupled to the sweep member 270, so when the
sweep control knob 202 is rotated, both the sweep member 270 and
the indexing cassette 227 rotate in unison, i.e., the angle of
rotation of the sweep control knob 202 matches the angle of
rotation of the sweep member 270 and the indexing cassette 227. It
is to be appreciated that additional gearing may be included to
adjust the speed of rotation for either or both of the sweep
control knob 202 and the indexing cassette 227.
[0231] As seen in FIG. 28A, the indexing cassette 227 may include a
plurality of indexing stops or divots 216. Although this variation
of the indexing cassette 227 contains divots, other forms such as
grooves or ridges, as non-limiting examples, may also serve an
indexing purpose. The indexing stops 216 may have a twofold
benefit. First, they allow incremental rotational indexing as the
physician rotates the control knob 202. This incremental indexing
is permitted due to the bending, torsion and axial strength
characteristics of the system 100 permitting little or no
misalignment between the distal and proximal ends of the system. A
secondary advantage of the indexing stops 216 is that they allow
incremental axial indexing as the physician advances the control
knob 202 in an axial direction to bend or steer the distal portion
122 of the debulking catheter system 100 by moving the sweep member
270 in an axially distal direction.
[0232] As shown, any number of positions 218, 220, 222, 224 can be
created on the indexing cassette 227. As shown in FIG. 28A, a
spring plunger 226 can provide tactile feedback to the physician as
the control knob 202 rotates. Once the physician desires to bend or
steer the debulking system 100 by moving the knob 202 in an axial
direction 228, the physician desirably may feel movement of the
knob 202 (via the spring plunger 226) into the second 220 and third
222 stop positions (for example), as shown in FIG. 28B.
[0233] As shown, the control knob 202 may also include an
orientation marker 214 that may correspond to the weakened section
of the sweep frame 250 (not shown). The orientation marker 214
could also correspond to a side of the sweep frame 250 that is
opposite to a spine 256 of the sweep frame. Because the orientation
marker 214 may be aligned with the sweep frame in such a manner,
the physician knows that the catheter 120 would bend in a direction
corresponding to the orientation marker 214. This allows the
physician to identify the orientation of the cutting assembly 102
as it sweeps within the body lumen by observing the orientation of
the orientation marker 214 as the physician rotates the sweep
control knob 202. Even if the one-to-one relationship may be lost,
the indexing knob 202 adds a fine visual control to direct the
distal portion 122 in defined steps or increments. This control can
be useful because the physician can direct the cutter 108 within
the immediate vicinity to work on areas that need to be resected,
versus losing position due to excessive movement. An atherectomy or
tissue debulking system having features that allow pushability as
well as torsional strength allow the physician greater feedback and
control when trying to steer the cutting assembly 102 towards a
desired treatment site within the body.
[0234] As described above, the catheter chassis 204 includes a
sweep control knob 202 coupled to the sweep member 270. The sweep
control knob 202 can axially advance the sweep member 270 to cause
deflection of the sweep frame 250 and distal portion 122 of the
catheter 120. In addition, the sweep control knob 202 can rotate
independently relative to the torque shaft 114 and rotatable cutter
108 in the cutting assembly 102.
[0235] As shown in FIG. 29A, distal movement of the sweep control
knob 202 advances the sweep member 270 to deflect the catheter tip
and cutting assembly 102. The degree of the deflection is
controlled by the amount the sweep control knob 202 is advanced.
The axial advancement of the sweep member 270 is limited by the
maximum deflection of the sweep frame 250. To allow the cutter
assembly 102 and distal portion 122 to be straight and undeflected,
the sweep member 270 may be withdrawn proximally by the sweep
control knob 202. This may cause removal of the axial force from
the sweep frame 250 (in some variations, the sweep frame can be set
in a straight configuration). In other variations, the sweep
control knob 202 retracts the catheter body relative to the sweep
frame 250 and/or member 270 to deflect the catheter tip and cutting
assembly 102.
[0236] As shown in FIG. 29B, the sweep control knob 202 can be
rotated to sweep the cutting assembly 102 in an arc manner.
Although, sweeping of the cutting assembly 102 can also occur via
manual operation, i.e., rotation of the handle 200. Variations of
the handle 200 include sweep members 270 that can be selectively
coupled to a sweep mechanism i.e., a sweep control motor (not
shown), to activate an automated rotation. This may allow the
physician to have a smooth, continuous, automated means to sweep
the cutter assembly 102 without any manual effort.
[0237] The systems, devices, and methods of the present invention
allow a physician to accurately determine the rotation of the
cutting assembly 102 since the rotation of the cutting assembly
closely corresponds to the rotation of the control knob 202. Such
close correspondence is not available unless the catheter body 120
and/or sweep member 270 has sufficient bending, torsion and axial
strength characteristics, as previously discussed. Accordingly, a
further aspect of the system 100 occurs when these catheter
bodies/sweep members are coupled to a handle 200 having a sweep
control knob 202 that enables indexing and monitoring of the
orientation of the cutter assembly 102. Clearly, this one-to-one
relationship can be lost when the distal portion 122 or cutting
assembly 102 encounters sufficient resistance against or within a
lesion, occlusion, or diseased tissue. However, in such cases, the
system 100 is still able to debulk tissue and perform its function
even though the response may not be one-to-one. In any case, the
ability to maintain a near one-to-one relationship and minimize
rotational misalignment between the proximal and distal portions of
the system 100 allows for steering of the debulking system 100
towards the treatment site.
[0238] b. Cutter Rotation and Aspiration
[0239] FIG. 30 shows the motor gear 206 adapted for rotation of the
catheter chassis gear (torque shaft gear) 207, with the torque
shaft 114 passing through and coupled to the torque shaft gear 207.
A transfer propeller 212 may be rigidly attached to the torque
shaft 114 to pump aspirated tissue debris 8 from the catheter 120
out into an attached aspiration reservoir. The torque shaft 114 may
include one or more bearings 210. A seal 211 adjacent to the
bearing 210 prevents aspirated tissue debris from leaking
proximally through the bearing 210.
[0240] As previously described, the torque shaft 114 may have
conveying members or helical grooves 118 on its outer diameter
and/or within the central guidewire lumen 130. During a procedure
run, a motor 150 drives the gear 206 to rotate. This causes
rotation of the drive shaft 208, the transfer propeller 212, the
torque shaft 114, and the cutter 108 all in the same rotational
sense. Thus the cutter assembly 102 effectively cuts plaque 8 and
may further grind the plaque into smaller pieces, and then drives
the debris 8 back into the helical groove 118 on the torque shaft
114. The rotating helical grooves 118 winds the debris back into
the catheter chassis 204, and the debris is then transferred to an
aspiration reservoir by the transfer propeller 212. The propeller
212 can take the form of a screw or a series of circumferentially
arranged angled fan blades, for example. The cutter 108 may be
rotated at speeds of ranging from about 8,000 rpm to about 25,000
rpm, although higher and lower speeds are within the scope of the
invention. An alternative design would have the aspiration
reservoir built into the catheter hub 204 and/or handle base
201.
[0241] The system 100 may also include a vacuum source or pump 152
to assist in evacuation of debris created by operation of the
device. Any number of pumps or vacuum sources may be used in
combination with the system. For example, a peristaltic pump may be
used to drive materials from the system and into a waste container.
FIG. 25A also shows the system 100 coupled to a fluid source 154.
As with the rotating mechanism 150, the vacuum source and/or fluid
source may be coupled to the system 100 e.g., at the handle 200,
from inside or outside the surgical field.
[0242] c. Irrigation
[0243] FIG. 27 shows the catheter chassis 204 as having a flush
port 129. The flush port 129 provides a means for injecting a fluid
such as heparinized saline or any other medicine into the catheter
body 120 and catheter chassis 204 to keep blood and tissue debris
from clogging the space between components in the device. The flush
port 129 can also help lubricate moving components within the
catheter 120. One desirable fluid path is along the length of the
catheter 120 in the space between the catheter body 120 and sweep
member 270. Drugs or fluids can be introduced via the flush port
129 for flow out of one or more openings 131 near the distal
portion 122 or cutting assembly 102. Drugs flushing out near the
cutting assembly 102 can then infuse into the vessel wall. Using
thrombus-inhibiting, stenosis-inhibiting, and/or anti-inflammatory
drugs, for example, may help prevent restenosis after a
thrombectomy or atherectomy procedure. Possible drugs may include
rapamycin and analogs such as everolimus, biolimus, and sirolimus;
M-prednisolone; interferon y-1b; leflunomide; mycophenolic acid;
mizoribine; cyclosporine; tranilast; biorest; tacrolimus; taxius;
clopidogrel; rapamycin; paclitaxel; botox; lydicane; Retin A
Compound; glucosamine; chondroitin sulfate; or geldanamycin analogs
17-AAG or 17-DMAG, as non-limiting examples.
[0244] A wide range of other bioactive materials can be delivered
by the system 100. Additional examples include heparin, covalent
heparin, or another thrombin inhibitor, hirudin, hirulog,
argatroban, D-phenylalanyl-L-poly-L-arginyl chloromethyl ketone, or
another antithrombogenic agent, or mixtures thereof; urokinase,
streptokinase, a tissue plasminogen activator, or another
thrombolytic agent, or mixtures thereof; a fibrinolytic agent; a
vasospasm inhibitor; a calcium channel blocker, a nitrate, nitric
oxide, a nitric oxide promoter or another vasodilator; Hytrin.RTM.
or other antihypertensive agents; an antimicrobial agent or
antibiotic; aspirin, ticlopidine, a glycoprotein IIb/IIIa inhibitor
or another inhibitor of surface glycoprotein receptors, or another
antiplatelet agent; colchicine or another antimitotic, or another
microtubule inhibitor, dimethyl sulfoxide (DMSO), a retinoid or
another antisecretory agent; cytochalasin or another actin
inhibitor; or a remodeling inhibitor; deoxyribonucleic acid, an
antisense nucleotide or another agent for molecular genetic
intervention; methotrexate or another antimetabolite or
antiproliferative agent; tamoxifen citrate, Taxol.RTM. or the
derivatives thereof, or other anticancer chemotherapeutic agents;
dexamethasone, dexamethasone sodium phosphate, dexamethasone
acetate or another dexamethasone derivative, or another
anti-inflammatory steroid or non-steroidal anti-inflammatory agent;
cyclosporin or another immunosuppressive agent; trapidil (a PDGF
antagonist), angiopeptin (a growth hormone antagonist), angiogenin,
a growth factor or an antigrowth factor antibody, or another growth
factor antagonist; dopamine, bromocriptine mesylate, pergolide
mesylate or another dopamine agonist; .sup.60Co(5.3 year half
life), .sup.192Ir(73.8 days), .sup.32P(14.3 days), .sup.111In(68
hours), .sup.90Y(64 hours), .sup.99mTc(6 hours) or another
radiotherapeutic agent; iodine-containing compounds,
barium-containing compounds, gold, tantalum, platinum, tungsten or
another heavy metal functioning as a radiopaque agent; a peptide, a
protein, an enzyme, an extracellular matrix component, a cellular
component or another biologic agent; captopril, enalapril or
another angiotensin converting enzyme (ACE) inhibitor; ascorbic
acid, alpha tocopherol superoxide dismutase, deferoxamine, a
21-aminosteroid (lasaroid) or another free radical scavenger, iron
chelator or antioxidant; a .sup.14C-, .sup.3H-, .sup.131I-,
.sup.21P- or .sup.36S-radiolabelled form or other radiolabelled
form of any of the foregoing; estrogen or another sex hormone; AZT
or other antipolymerases; acyclovir, famciclovir, rimantadine
hydrochloride, ganciclovir sodium, Norvir, Crixivan, or other
antiviral agents; 5-aminolevulinic acid,
meta-tetrahydroxyphenylchlorin, hexadecafluoro zinc phthalocyanine,
tetramethyl hematoporphyrin, rhodamine 123 or other photodynamic
therapy agents; an IgG2 Kappa antibody against Pseudomonas
aeruginosa exotoxin A and reactive with A431 epidermoid carcinoma
cells, monoclonal antibody against the noradrenergic enzyme
dopamine betahydroxylase conjugated to saporin or other antibody
targeted therapy agents; gene therapy agents; and enalapril and
other prodrugs; Proscar.RTM., Hytrin.RTM. or other agents for
treating benign prostatic hyperplasia (BHP) or a mixture of any of
these; and various forms of small intestine submucosa (SIS).
III. Additional System Features
[0245] A. Energy Delivery
[0246] The construction of the cutting assembly 102 can provide for
additional modes of energy delivery. For example, when the system
100 excises tissue in vascularized regions excessive bleeding can
occur (e.g., lung biopsy and excision). Accordingly, energy can be
delivered to the target site via a conductive cutter assembly
(i.e., the housing 104 and/or the cutter 108, for example). Sound
energy (ultrasound), electrical energy (radio frequency current),
or even microwaves can be used for this purpose. These energy
sources delivered through the cutter assembly 102 can also be used
to denature tissue (collagen), shrink tissue, or ablate tissue.
Optionally, a guidewire, if used, may be removed and replaced with
a cable for UV energy delivery and/or to deliver radiation
treatments, all as a standalone or combination treatment.
[0247] B. Distal Portion Visualization
[0248] FIGS. 31A and 31B show variations of a sweep frame 250
having a visualization feature 284 that permits a physician to
determine orientation and direction of articulation of the cutting
assembly 102 when the device is viewed under non-invasive imaging,
e.g., fluoroscopy. FIG. 30A shows one variation of the
visualization feature 284 as being a notch or opening 284 on a side
of the sweep frame 250 that is perpendicular to the direction in
which the frame bends. In one example, the visualization mark is
placed 90 degrees relative to the spine 256. Although the feature
284 is shown on the right side of the sweep frame 250, any side may
be used so long as the location and orientation of the feature 284
conveys to the physician the orientation and direction of bend of
the sweep frame 250 via non-invasive imaging.
[0249] FIG. 31B illustrates another variation of an orientation
feature 284 comprising a marking substance (e.g., a radiopaque
additive and/or a highly radiopaque metal deposited on the sweep
frame 250, as non-limiting examples). In any case, the
visualization feature 284 must provide sufficient contrast against
the frame 250 when viewed in a non-invasive imaging modality. These
visualization means may also include arrangements such as a notch,
opening, tab, protrusion, or deposition, for example.
[0250] As shown, both visualization features 284 are on the
right-hand side of the sweep frame 250 when the spine 256 of the
frame 250 is directly adjacent to the physician. In this position,
articulation of the sweep frame (that occurs in a direction away
from the spine), causes the sweep frame 250 to deflect away from
the physician. Accordingly, when the physician observes the
visualization marks 284 to the right of the device, the physician
will know that flexure of the sweep frame 250 will occur directly
away from the physician. Clearly, the present invention includes
any number of visualization features or placement of such features
on any portion of the sweep frame 250 or other portions of the
distal section 122, so long as the physician will be able to
determine the orientation and direction of bend of the sweep frame
250 from viewing the visualization mark(s) 284.
[0251] C. Flushing Solutions
[0252] Infusing solutions (e.g., flushing) into the target
treatment site may be desirable. Infused cool saline can prevent
heating of blood and other tissue, which reduces the possibility of
thrombus or other tissue damage. Heparinized saline can also
prevent thrombus and thin out the blood to help maximize
effectiveness of aspiration. The flush can also include
thrombus-inhibiting, stenosis-inhibiting or anti-inflammatory drugs
such as those listed above. This may help to prevent restenosis and
may result in better long term patency. The flush may include
paralytics or long-acting smooth muscle relaxants to prevent acute
recoil of the vessel. FIGS. 32A to 32C illustrate variations of
flushing out the system 100. The flush can be infused through the
guidewire lumen 130 (FIG. 32A), a side lumen 132 in the catheter
body 120 (FIG. 32B), and/or sideports 127 in the guidewire 128
(FIG. 32C).
[0253] Flush can come out of a port at the distal end of the cutter
108 pointing the flush proximally to facilitate aspiration.
Alternatively, by instilling the flush out the distal end of the
cutter housing 104 over the rounded surface, the flow may be
directed rearward by the Coanda effect. The restenosis-inhibitors
can be carried by microcapsules with tissue adhesives or
velcro-like features on the surface to stick to inner vessel
surface so that the drug adheres to the treatment site, and to
provide a time-release controlled by the resorption or dissolving
of the coating to further improve efficacy. Such velcro-like
features may be constructed with nanoscale structures made of
organic or inorganic materials. Reducing the volume of foreign
matter and exposing remaining tissue and extracellular matrix to
drugs, stimulation, or sensors can make any of these techniques
more effective.
[0254] Another way to infuse fluid is to supply pressurized fluid
at the proximal portion of the guidewire lumen 130 (e.g., gravity
and/or pressure feed with an intravenous bag, for example). A
hemostatic seal with a side branch is useful for this purpose;
tuohy-borst adapters are one example of a means to implement
this.
[0255] Balancing the relative amount of infusion versus fluid
volume aspirated allows control over the vessel diameter;
aspirating more fluid than is instilled will evacuate the vessel,
shrinking its diameter, and allow cutting of lesion at a greater
diameter than the atherectomy catheter. This has been a problem for
certain open cutter designs that use aspiration, because the
aggressive aspiration required to trap the embolic particles
evacuates and collapses the artery around the cutter blades. This
is both a performance issue because the cutter can bog down from
too high torque load, and the cutter can easily perforate the
vessel. The cutter assembly 102 designs described herein obviates
both problems, and further requires less aggressive aspiration to
be effective, giving a wider range of control to the user.
[0256] D. Rapid Exchange
[0257] FIG. 33 illustrates a variation of a system 100 configured
for rapid exchange. As shown, the system 100 includes a short
passage, lumen, or other track 136 for the purpose of advancing the
device 100 over the guidewire 128. However, the track 136 does not
extend along the entire length of the catheter 120. Moreover, an
additional portion of the track 136 may be located at a distal end
134 of the catheter 120 to center the guidewire 128.
[0258] This feature permits rapid decoupling of the system 100 and
guidewire 128 by merely holding the guidewire still and pulling or
pushing the system 100 over the guidewire. One benefit of such a
feature is that the guidewire 128 may remain close to the procedure
site while being decoupled from the system 100. Accordingly, the
surgeon can advance additional devices over the guidewire 128 and
to the site in a rapid fashion. This configuration allows for quick
separation of the catheter 120 from the guidewire 128 and
introduction of another catheter over the guidewire since most of
the guidewire is outside of the catheter.
[0259] E. Over the Wire
[0260] As shown in FIG. 34, centering the tip of the cutting
assembly 102 over the guide wire 128 improves the control, access
and positioning of the cutting assembly 102 relative to a body
lumen or vessel 2. To accomplish this, the cutting assembly 102 can
have a central lumen 130 to accommodate a guide wire 128.
Variations of the system 100 include a central guide wire lumen 130
that may run the length of the catheter 120 through all or some of
the central components including the torque shaft 114, the cutter
108, and the handle 200. As noted above, the guidewire 128 can be
affixed to the housing 104 or other non-rotational component of the
cutting assembly 102. In such a case, the guidewire 128 may
preferably be a short segment that assists with navigation of the
device through an occluded portion of a body lumen. However, the
system 100 can also operate without a guidewire since the distal
portion 122 is steerable like a guidewire.
[0261] F. Combination Treatments
[0262] The devices, systems, and methods of the present invention
may also be used in conjunction with other structures placed in the
body lumens. For example, as shown in FIG. 35, one way to protect
the vessel and also allow for maximum plaque volume reduction is to
deploy a protective structure such as a stent, thin expandable coil
or an expandable mesh 182 within a lesion. As this structure
expands after deployment, the thin wire coil or the struts push
radially outward through the plaque until it becomes substantially
flush with the vessel wall. This expansion of thin members requires
minimal displacement of plaque volume and minimizes barotrauma
produced in balloon angioplasty or balloon expanded stent delivery.
Once the protective structure 182 has expanded fully, atherectomy
can be performed to cut away the plaque 4 inside the vessel 2 to
open up the lumen. The vessel wall is protected by the expanded
structure 182 because the structure members (coil or struts) resist
cutting by the atherectomy cutter 108, and are disposed in a way
that they cannot invaginate into the cutter housing 104 (and
thereby be grabbed by the cutter 108). It is also possible to
adjust the angle of the windows 106 on the guarded cutter housing
106 so that they do not align with the struts or coils. The
adjustment to orientation may be accounted for in the coil or strut
design, in the cutter housing design, or both.
[0263] Furthermore, the protective member 182 can be relatively
flexible and have a low profile (i.e., thin elements), so that it
may be left in place as a stent. Because the stent in this case
relies mainly upon atherectomy to restore lumen patency, it may be
designed to exert far less radial force as it is deployed. This
allows usage of greater range of materials, some of which may not
have as high of stiffness and strength such as bioresorbable
polymers and metal alloys. Also, this allows a more resilient
design, amenable to the mechanical forces in the peripheral
arteries. It also minimizes flow disruption, to minimize
hemodynamic complications such as thrombosis related to the
relatively low flows found in the periphery. It is also possible to
perform atherectomy prior to placing the protective structure 182,
whether or not atherectomy is performed after placing the
structure.
[0264] As described, it may be advantageous to couple atherectomy
with stenting. By debulking the lesion, a lesser radial force is
required to further open the artery and maintain lumen diameter.
The amount of debulking can be tuned to perform well in concert
with the mechanical characteristics of the selected stent 182. For
stents that supply greater expansion and radial force, relatively
less atherectomy is required for satisfactory result.
[0265] An alternative treatment approach is to debulk the lesion
substantially, which will allow placement of a stent optimized for
the mechanical conditions inherent in the peripheral anatomy. In
essence, the stent can support itself against the vessel wall and
supply mild radial force to preserve luminal patency. The stent may
be bioresorbable, and/or drug eluting, with the resorption or
elution happening over a period for days to up to 12 weeks or more,
as a non-limiting example. A period of 4 to 12 weeks matches well
with the time course of remodeling and return to stability as seen
in the classic wound healing response, and in particular the known
remodeling time course of arteries following stent procedures.
[0266] In addition, the stent geometry can be optimized to minimize
thrombosis by inducing swirl in the blood flow. This has the effect
of minimizing or eliminating stagnant or recirculating flow that
leads to thrombus formation. Spiral construction of at least the
proximal (upstream) portion of the stent 182 may achieve this. It
may also be beneficial to ensure that flow immediately distal to
the stent does not create any stagnant or recirculation zones, and
swirl is a way to prevent this as well.
[0267] It is also possible to use the devices, systems, and methods
described herein to restore patency to arterial lesions by
debulking in-stent restenosis. FIG. 35 shows the system 100
removing lesions within a stent or coil.
[0268] The system 100 may be further configured with a balloon 138
or other mechanism proximal to the cutter, for adjunctive
angioplasty, stent, and/or drug delivery (see FIGS. 40A and 40B for
example). In combination, the system 100 may first debulk a vessel
with the mechanism 138 undeployed (see FIG. 40A), and then deploy a
mechanism, such as drug coated balloon 138, because the balloon
drug delivery may be more uniform and effective drug delivery
compared to drug delivery within an untrimmed vessel (see FIG.
40B). The system 100 may also deliver drug therapy through the
guidewire lumen 130. For example, a fluid may be delivered through
the lumen, and with the cutting assembly 102 steered toward plaque
and/or a wall of the vessel, a jet of drug therapy may be delivered
to the target site.
[0269] The system 100 may optionally be configured to deliver
self-expanding stents. This feature provides convenience to the
user and greater assurance of adjunctive therapy at the intended
location where atherectomy was performed.
[0270] G. Additional System Features
[0271] Additional components may be incorporated into the devices,
systems, and methods described herein. For example, it can be
desirable to incorporate sensors and/or transducers 144 into and/or
onto the distal portion 122 of the catheter body 120 and/or the
cutting assembly 102 to characterize the plaque and/or to assess
plaque and wall thickness and vessel diameter for treatment
planning (see FIGS. 41A and 41B). Transducers 144 may also be
desired to indicate the progression of debulking or proximity of
the cutter 108 to a vessel wall. For example, pressure sensors 144
mounted on the catheter housing 104 or cutter 108 can sense the
increase in contact force encountered in the event that the housing
is pressed against the vessel wall. Temperature sensors 144 can be
used to detect vulnerable plaque. Ultrasound transducers 144 can be
used to image luminal area, plaque thickness or volume, and wall
thickness. Electrodes 144 can be used for sensing the impedance of
contacted tissue, which allows discrimination between types of
plaque and also vessel wall. Electrodes can also be used to deliver
impulses of energy, for example to assess innervation, to either
stimulate or inactivate smooth muscle, or to characterize the
plaque (composition, thickness, etc.). For example, transient spasm
may be introduced to bring the vessel to a smaller diameter making
it easier to debulk, then reversed either electrically or
pharmaceutically. Electrical energy may also be delivered to
improve the delivery of drugs or biologic agents, by causing the
cell membrane to open in response to the electric stimulation
(electroporation). One method of characterization by electrical
measurement is electrical impedance tomography.
[0272] Optical coherence tomography (OCT) can be used to make
plaque and wall thickness measurements. As seen in FIG. 42, an OCT
device 146 may be provided in conjunction with the cutter assembly
102, for example. The OCT device 146 may also be introduced into
the target area through the guidewire lumen 130. The steerable
distal portion 122 allows for controlled viewing of not only the
center portions of the vessel, but the sidewalls can be imaged as
well. The forward cutting assembly 102 combined with the OCT device
146 allows for imaging of the targeted treatment area before,
during, and after debulking the vessel. A simple saline flush may
be used to reduce absorption of the optical waves in the blood to
improve imaging of the viewing area.
IV. Lower Extremity Anatomy
[0273] FIG. 36 shows the arteries of the pelvis and the lower
limbs. As previously described, the devices, systems, and methods
are well suited for use in this peripheral region. The main artery
extending from the pelvis is the iliac artery, with the internal
iliac artery supplying most of the blood to the pelvic viscera and
wall.
[0274] The external iliac arteries diverge through the greater
(false) pelvis and enter the thighs to become the right and left
femoral arteries. Both femoral arteries send branches superiorly to
the genitals and the wall of the abdomen. The profunda femoris
artery (also known as the deep femoral artery) branches off of the
proximal superficial femoral artery soon after its origin. The
profunda travels down the thigh closer to the femur than the
femoral artery, running between the pectineus and the adductor
longus muscles.
[0275] The femoral passes through the hunter's canal and continues
down the medial and posterior side of the thigh posterior to the
knee joint, a very flexible region, where it becomes the popliteal
artery. Between the knee and ankle, the popliteal runs down on the
posterior aspect of the leg and is called the posterior tibial
artery. Inferior to the knee, the peroneal artery branches off the
posterior tibial to supply structures on the medial side of the
fibula and calcaneus bones (both not shown). In the calf, the
anterior tibial artery branches off the popliteal and runs along
the anterior surface of the leg. At the ankle it becomes the
dorsalis pedis artery. At the ankle, the posterior tibial divides
into the medial and lateral plantar arteries. The lateral plantar
artery and the dorsalis pedis artery unite to form the plantar
arch. From this arch, digital arteries supply the toes.
[0276] A. Representative Uses of the Atherectomy System
[0277] The debulking system 100 as described makes possible a
single insertion of the catheter 120 for providing treatment of
occluded body lumens, including the removal of lesions from
arteries in the lower extremity, the single insertion of the
catheter 120 including removal of the debulked material. The
debulking system 100 is adapted to perform debulking in a wide
range of vessels, including arteries in the upper and lower
extremity, representative examples of which will be described for
the purpose of illustration.
[0278] The system 100 may be used in a wide range of artery
configurations found in the leg, including tortuous and straight,
and may be used in short and long vessels, i.e., 20 cm or longer.
The system 100 is well suited for use above the knee up to the
common femoral artery, although it is to be appreciated that the
system may be used in arteries proximal to the common femoral
artery. The system is also well suited for use in arteries below
the knee, and may be used all the way down to the ankle and/or
foot.
[0279] A wide range of vessel sizes may be found in the leg, all of
which may be accessible for use with the system 100. A typical
diameter for the catheter 120 ranges from about 1.0 mm to about 3.0
mm, providing access for a wide range of target sites. For example,
the common femoral artery ranges in diameter between about 6 mm to
about 7 mm; the superficial femoral artery ranges between about 4
mm to about 7 mm; the popliteal artery ranges between about 3 mm to
about 5 mm; and the tibial artery ranges between about 2 mm to
about 4 mm.
[0280] The profunda and the common femoral arteries have been found
to be less than desirable areas for stenting and/or ballooning, for
example, because this area should remain available for bypass graft
of the femoral artery. The devices, systems, and methods for
atherectomy in these regions provide a good solution for
debulking.
[0281] A variety of options exists for access to target sites
within the leg. Based on access and desired target area, a variety
of possible working lengths exist for the system 100. For example,
four size options may be available: 1) ipsilateral (same side)
access and down to a site above the knee; 2) ipsilateral access and
down to a site below the knee; 3) contralateral (opposite side)
access and across and down to a site above the knee; and 4)
contralateral access and across and down to a site below the knee.
The size options take into account access from various anatomical
access points such as femoral artery, brachial artery, etc.
[0282] A typical working length of the system 100 ranges from about
110 cm to about 130 cm for ipsilateral approaches (see FIG. 37),
and from about 130 cm to about 150 cm for contralateral approaches
(see FIG. 38) possibly extending below the knee. Contralateral
access may be desired and/or necessary because the introducer may
be blocking the treatment area.
[0283] V. Instructions for Use of the System
[0284] The instructions for use 404 can direct use of the
catheter-based system 100 via a peripheral intravascular access
site, such as in the femoral artery, optionally with the assistance
of image guidance. Image guidance includes but is not limited to
fluoroscopy, ultrasound, magnetic resonance, computed tomography,
optical coherence tomography, or combinations thereof.
[0285] The system 100 may be used in a procedure that takes less
time than prior debulking devices, e.g., a debulking procedure may
be performed in 45 minutes or less. In addition, only a single
insertion of the system 100 is needed for a procedure (i.e., no
catheter exchange), as compared to requiring multiple catheter
exchanges for prior debulking devices. This is because the system
100 is adapted to "sweep" the lumen of materials, the sweep feature
allowing the single system 100 to create a passage in the lumen
having a ratio ranging from about one to up to about four times the
diameter of the catheter 120. The system is adapted to debulk
vessels ranging in diameter from about one mm to about ten mm,
although smaller and larger diameter vessels are within the scope
of the invention.
[0286] Prior to use, a clinician identifies the particular vascular
region to which a prescribed treatment using the atherectomy system
100 will be applied. The site is prepped for vascular access to the
artery to be treated. The debulking system 100 may be removed from
the sterile package. The distal portion 122 of the system 100 is
inserted into the artery and advanced to the target site. A
guidewire may also be used during this phase of the procedure. The
steering capabilities of the system 100 may be used to assist the
surgeon to steer the system through tortuous vessels to the target
site. Once the cutting assembly is at the target site, the surgeon
powers the system 100 by pressing or activating the on/off means
234. The surgeon is able to control the operation of the system 100
with only one hand on the ergonomic handle 200. With the cutter 108
rotating at a desired RPM, under image guidance, the surgeon slowly
advances the catheter 120 distally to cut and remove plaque. The
surgeon is able to use the sweeping capabilities of the system 100
to create a sweeping motion of the cutting assembly 102 to sweep
and cut the lesion in an arcing path, thereby producing a diameter
clearing in the vessel that may be up to four times the diameter of
the catheter 120. As the cutting is taking place, system first cuts
the material with the first cutting edge 112, and then further cuts
or grinds the cut material into smaller pieces for easier
transportation through the length of the catheter 120, through the
catheter chassis 204, and out the aspiration port 209 to a
container.
[0287] Depending on the desired treatment, the system 100 may be
used for combination treatments as previously described. For
example, the guidewire, if used, may be removed and replace with
additional treatment options, such as UV radiation. Or, the
flushing system as previously described may be used to infuse drugs
into the target site, possibly before, during, or after the
debulking procedure.
[0288] After the lesion has been removed from the vessel, the
surgeon powers down the system, and slowly withdraws the catheter
from the vessel. The entry location is cleaned and bandaged. The
system 100 may be disposed of per hospital or facility
guidelines.
[0289] Additional or alternative instructions may describe various
procedures and uses of the system. For example, the instructions
for use may describe the use of the catheter, the instructions
comprising the operations of introducing the catheter assembly into
the blood vessel and positioning the tissue cutting assembly at or
near a site in need of tissue debulking, manipulating the tissue
removal assembly to debulk tissue in the blood vessel, creating a
cleared tissue diameter within the vessel of at least two times the
diameter of the tissue removal assembly, and removing the cleared
tissue.
[0290] Instructions for use describing the use of the catheter may
also comprise the operations of introducing the catheter assembly
into the blood vessel and positioning the tissue cutting assembly
at or near a site in need of tissue debulking, manipulating the
deflection control device thereby deflecting a distal portion of
the catheter, and manipulating the rotation control device thereby
rotating the distal portion of the catheter in an arcuate path.
[0291] Additional instructions for use describing the operation of
the catheter may comprise introducing the catheter assembly into
the blood vessel and positioning the tissue cutting assembly at or
near a site in need of tissue debulking, deflecting the bending
frame in a direction of a first radial side of the bending frame by
moving a sweep member at or near the proximal end of the catheter,
thereby causing the tissue cutting assembly to deflect in the
direction of the first radial side, rotating a torque shaft
extending through the catheter and coupled to at least the
rotatable cutter, moving the sweep member independently of the
torque shaft for rotating the bending frame and causing the tissue
cutting assembly to sweep in an arcuate path relative to an axis of
a proximal end of the bending frame, and removing the occlusive
material.
[0292] Additional instructions for use describing the operation of
the catheter may comprise providing a catheter sized and configured
to be introduced into the blood vessel, the catheter including a
tissue cutting assembly at or near a distal end of the catheter,
the tissue cutting assembly including a rotatable cutter for
debulking the tissue from the blood vessel, providing a control
handle coupled to the catheter assembly, the control handle
including steering means for steering the tissue cutting assembly,
introducing the catheter into an iliac artery, advancing the
catheter into a femoral artery, a profunda femoris artery, an
artery in the hunter's canal, a popliteal artery, a tibial artery,
a peroneal artery, a dorsalis pedis artery, a medial plantar
artery, a lateral plantar artery, or a digital artery, positioning
the tissue cutting assembly at or near a target site in the femoral
artery, the profunda femoris artery, the artery in the hunter's
canal, the popliteal artery, the tibial artery, the peroneal
artery, the dorsalis pedis artery, the medial plantar artery, the
lateral plantar artery, or the digital artery, operating the
steering means by applying a first force to the steering means, the
first force causing the distal portion of the catheter to deflect
in a radial direction, operating the steering means by applying a
second force to the steering means, the second force causing the
distal portion of the catheter to rotate in an arcuate path while
the distal portion is deflected in the radial direction, advancing
the catheter distally to sweep the target site thereby allowing the
rotatable cutter to debulk tissue from the target site in the
arcuate path, and removing the debulked tissue from the target
site, thereby treating the blood vessel.
VI. System Kit
[0293] As FIG. 39 shows, the system 100 and devices as just
described can be consolidated for use in a multiple piece
functional kit 400. It is to be appreciated that the system 100 and
devices are not necessarily shown to scale.
[0294] The kit 400 can take various forms. In the illustrated
embodiment, the kit 400 comprises an individual package comprising
a sterile, wrapped, peel-open assembly. The kit 400 may include an
interior tray 402 made, e.g., from die cut cardboard, plastic
sheet, or thermo-formed plastic material, which hold the contents.
The kit 400 also preferably includes instructions or directions 404
for using the contents of the kit 400 to carry out a desired
procedure, as described above.
[0295] The kit 400 provides the main components of the debulking
system 100 as described, including the cutting assembly 102, the
catheter 120, and the handle 200, assembled and ready for use. In
one embodiment the handle base 201 may not be coupled to the
catheter chassis 204. The remaining components may be optional
ancillary components used in the deployment of the system 100,
e.g., a conventional vascular access sheath 406; a conventional
(e.g., 0.014 inch) guide wire 128; and bags containing heparinized
saline for catheter flushing and contrast for angiography 408.
[0296] The instructions for use 404 can, of course vary. The
instructions for use 404 can be physically present in the kit, but
can also be supplied separately. The instructions for use 404 can
be embodied in separate instruction manuals, or in video or audio
recordings. The instructions for use 404 can also be available
through an internet web page.
[0297] The foregoing is considered as illustrative only of the
principles of the invention. Furthermore, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and operation shown and described. While the preferred
embodiment has been described, the details may be changed without
departing from the invention, which is defined by the claims.
* * * * *