U.S. patent application number 12/388343 was filed with the patent office on 2009-06-11 for fixed stent delivery devices and methods.
This patent application is currently assigned to Xtent, Inc.. Invention is credited to Bernard Andreas, Jeffry J. Grainger.
Application Number | 20090149863 12/388343 |
Document ID | / |
Family ID | 34423235 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090149863 |
Kind Code |
A1 |
Andreas; Bernard ; et
al. |
June 11, 2009 |
FIXED STENT DELIVERY DEVICES AND METHODS
Abstract
Stent delivery devices and methods include multiple stents or
stent segments mounted at fixed positions on an expandable member
of the stent delivery catheter. One or more of the fixed-position
stents may be selectively deployed in a body lumen such as a blood
vessel by positioning one or more sheaths to constrain some stents
while exposing others for deployment. Some embodiments include two
axially movable sheaths for serially deploying stents while
containing a portion of the expandable balloon from which stents
have been deployed. Other embodiments include inner and outer
balloon shafts to allow the balloon to be retracted into the
delivery catheter as stents are deployed. Devices and methods of
the invention provide enhanced serial deployment of multiple stents
or stent segments while reducing the risk of damage to an
expandable deployment member.
Inventors: |
Andreas; Bernard; (Redwood
City, CA) ; Grainger; Jeffry J.; (Portola Valley,
CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP;(CLIENT NO 021629-000000)
TWO EMBARCADERO CENTER, 8TH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Xtent, Inc.
Menlo Park
CA
|
Family ID: |
34423235 |
Appl. No.: |
12/388343 |
Filed: |
February 18, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10686025 |
Oct 14, 2003 |
|
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12388343 |
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Current U.S.
Class: |
606/108 |
Current CPC
Class: |
A61F 2002/9583 20130101;
A61F 2/958 20130101; A61F 2002/826 20130101 |
Class at
Publication: |
606/108 |
International
Class: |
A61F 2/86 20060101
A61F002/86 |
Claims
1. A stent delivery device for delivering a plurality of stent
segments to a treatment site, the device comprising: a catheter
shaft having a proximal end and a distal end; an expandable member
coupled with the catheter shaft near the distal end; a plurality of
stent segments mounted on the expandable member; and at least a
first axially movable sheath disposed over at least part of the
catheter shaft, the expandable member and the stent segments,
wherein the first sheath is adapted to constrain expansion of a
first portion of the expandable member and stent segments thereon
while allowing expansion of a second portion of the expandable
member and stent segments thereon.
2. A device as in claim 1, wherein each of the plurality of stent
segments is spaced apart from adjacent stent segments, so that each
stent segment can be expanded by the expandable member without
interfering with adjacent stent segments.
3. A device as in claim 1, further including at least a second
axially movable sheath disposed over part of the catheter shaft,
the expandable member and the stent segments, wherein the first
sheath is disposed proximally along the catheter shaft relative to
the second sheath, and wherein the first and second sheaths are
adapted to allow expansion and deployment of at least one stent
segment between the sheaths.
4. A device as in claim 3, wherein the second sheath is movable
distally to allow for deployment of at least one stent segment and
proximally to constrain a portion of the expandable member from
which at least one stent segment has been deployed.
5. A device as in claim 1, further including an inner shaft
slidably disposed within the catheter shaft, the expandable member
having a distal end coupled with the inner shaft for retracting
relative to the catheter shaft a portion of the expandable member
from which at least one stent segment has been deployed.
6. A stent delivery device for delivering a plurality of stent
segments to a treatment site, the device comprising: a catheter
shaft having a proximal end and a distal end; an expandable member
coupled with the catheter shaft near the distal end; a plurality of
stent segments mounted at fixed positions on the expandable member;
at least one axially movable sheath disposed over at least part of
the catheter shaft, the expandable member and the stent segments,
wherein the sheath is adapted to constrain expansion of a first
portion of the expandable member and stent segments thereon while
allowing expansion of a second portion of the expandable member and
stent segments thereon; and an inner shaft slidably disposed within
the catheter shaft, wherein the expandable member includes a distal
end coupled with the inner shaft for retracting relative to the
catheter shaft a portion of the expandable member from which at
least one stent segment has been deployed.
7. An interventional catheter device comprising: a catheter shaft
having a proximal end and a distal end; an expandable member
coupled with the catheter shaft near the distal end; a distal
sheath axially movable relative to the expandable member and
positionable over at least a distal portion thereof, and a proximal
sheath axially movable relative to the expandable member and the
distal sheath and positionable over at least a proximal portion of
the expandable member, wherein the distal and proximal sheaths are
axially positionable to expose a selected portion of the expandable
member to allow expansion thereof while covering another portion of
the expandable member to constrain expansion thereof.
8. A device as in claim 7, further comprising a plurality of stents
mounted on the expandable member.
9. A device as in claim 8, wherein the distal sheath is movable
distally to allow for deployment of at least one stent and
proximally to constrain a portion of the expandable member from
which at least one stent has been deployed.
10. A device as in claim 8, wherein at least a first of the stents
has a different characteristic than at least a second of the
stents, wherein the first and second stents are mounted at
different locations along the expandable member, and wherein the
characteristic is selected from the group consisting of diameter,
length, shape, geometry, stiffness, stent material, and coating
material.
11. A device as in claim 7, wherein the expandable member is
tapered along its length, and wherein the distal and proximal
sheaths are positionable to expose at least a first portion of the
expandable member having a first average cross-sectional diameter
while covering at least a second portion of the expandable member
having a second average cross-sectional diameter.
12. A device as in claim 11, wherein each of the plurality of
stents comprises a plurality of stent segments.
13. A device as in claim 12, wherein the length of each stent may
be selected by selecting the number of stent segments.
14. A device as in claim 7, wherein the expandable member includes
a first tapered portion having a first average cross-sectional
diameter and a second tapered portion having a second average
cross-sectional diameter, and wherein the distal and proximal
sheaths are positionable to expose the first portion while covering
the second portion.
15. A stent delivery device for delivering a plurality of stent
segments to a treatment site, the device comprising: a catheter
shaft having a proximal end and a distal end; a plurality of
self-expanding stent segments disposed on the catheter shaft; a
distal sheath axially movable relative to the stent segments and
positionable over at least one distal segment; and a proximal
sheath axially movable relative to the stent segments and the
distal sheath and positionable over at least one proximal segment,
wherein the distal and proximal sheaths are axially positionable to
expose one or more selected stent segments to allow expansion
thereof while covering one or more other stent segments to
constrain expansion thereof.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a divisional of, and claims the
benefit of U.S. patent application Ser. No. 10/686,025 filed Oct.
14, 2003 (Attorney Docket No. 021629-002000US) now U.S. Pat. No.
______, the full disclosure of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention. The present invention relates
generally to medical devices and methods. More particularly, the
invention relates to apparatus and methods for independently
delivering a plurality of stents or stent segments within a body
lumen.
[0003] Stenting has become an increasingly important treatment
option for patients with coronary artery disease. Stenting involves
the placement of a tubular prosthesis within a diseased coronary
artery to expand the arterial lumen and maintain the patency of the
artery. Early stent technology suffered from problems with
restenosis, the tendency of the coronary artery to become
re-occluded following stent placement. In recent years, however,
improvements in stent design and the advent of drug-eluting stents
have reduced restenosis rates dramatically. As a result, the number
of stenting procedures being performed in the United States,
Europe, and elsewhere has soared.
[0004] Stents are delivered to the coronary arteries using long,
flexible vascular catheters, typically inserted through a femoral
artery. For self-expanding stents, the stent is simply released
from the delivery catheter, and it resiliently expands into
engagement with the vessel wall. For balloon expandable stents, a
balloon on the delivery catheter is expanded which expands and
deforms the stent to the desired diameter, whereupon the balloon is
deflated and removed.
[0005] Despite many recent advances in stent delivery technology, a
number of shortcomings still exist. For example, current stent
delivery catheters are not capable of customizing the length of the
stent in situ to match the size of the lesion to be treated. While
lesion size may be measured prior to stenting, using angiography or
fluoroscopy, such measurements may be inexact. If a stent is
introduced that is found to be of inappropriate size, the delivery
catheter and stent must be removed from the patient and replaced
with a different device of correct size. Moreover, current stent
delivery devices cannot treat multiple lesions with a single
catheter. If multiple lesions are to be treated, a new catheter and
stent must be introduced for each lesion to be treated.
[0006] Additionally, currently available stent delivery devices are
not well-adapted for treating vascular lesions that are very long
and/or in curved regions of a vessel. Current stents have a
discrete length that is relatively short due to their stiffness. If
such stents were made longer, to treat longer lesions, they would
not conform well to the curvature of vessels or to the movement of
vessels on the surface of the beating heart. On the other hand, any
attempt to place multiple stents end-to-end in longer lesions is
hampered by the inability to maintain appropriate inter-stent
spacing and to prevent overlap of adjacent stents. Such
shortcomings in the prior art are addressed by the inventions
described in U.S. patent application Ser. No. 10/412,714 now U.S.
Pat. No. 7,137,993 (Attorney Docket No. 21629-000330), entitled
"Apparatus and Methods for Delivery of Multiple Distributed
Stents," filed on Apr. 10, 2003; and U.S. patent application Ser.
No. 10/637,713 now U.S. Pat. No. 7,309,350 (Attorney Docket No.
21629-000340), entitled "Apparatus and Methods for Delivery of
Multiple Distributed Stents," filed on Aug. 8, 2003; both
applications assigned to the assignee of the present invention, and
both applications being hereby incorporated fully by reference.
[0007] Even with improvements such as those described in the
above-referenced patent applications, further improvements in stent
delivery devices and methods are still being sought. For example,
it may often be advantageous to have stents or stent segments
mounted to an expandable deployment member, such as a balloon, at
fixed positions along the balloon rather than being slidable along
the balloon. This would lock in the relative positions of the stent
segments to avoid overlap, excessive spacing, rotational
misalignment during deployment, possible damage to the balloon or
stent coatings and the like. Stent segments fixed to a balloon
would also eliminate the need for a stent pusher to advance the
stent segments distally, thereby reducing the profile, stiffness
and complexity of the stent delivery catheter. Although
conventional stenting devices have a stent pre-mounted to a
balloon, currently available fixed-stent deployment devices
typically only allow a single stent of fixed length to be deployed
at once. It may be desirable, however, to tailor the length of the
stent to match the size of the lesion being treated. It may also be
desirable to deploy additional stents in one or more subsequent
deployments without removing the catheter from the body. It may
also be useful to deploy different sizes or types of stents during
the same intervention, use different portions of an expandable
member having different sizes or shapes, or select other
characteristics of each stent deployed in the same intervention.
These options are not provided by currently available pre-mounted
stent delivery devices.
[0008] Therefore, a need exists for improved stent delivery devices
and methods. Ideally, such devices and methods would reduce or
eliminate the need for sliding stents along an expandable member
such as a balloon. Also ideally, such devices and methods would
allow for selective deployment of one or more stent segments of a
stent. Such devices and methods should also allow in situ
customization of stent size, shape, length, material, coating, and
other characteristics to match the lesion being treated. Such
devices and methods would also ideally be more easily manufactured
and used than sliding-stent delivery devices. At least some of
these objectives will be met by the present invention.
[0009] 2. Description of the Background Art. U.S. patent
application Ser. Nos. 10/412,714 (now U.S. Pat. No. 7,137,993) and
10/637,713 (now U.S. Pat. No. 7,309,350), previously incorporated
by reference, describe apparatus and methods for delivery of
multiple distributed stents. U.S. Pat. Nos. 6,485,510 and 6,258,117
to Camrud et al. describe segmented stents with breakable
connections between the segments. U.S. Patent Application
Publication No. 2002/0156496 (inventor Chermoni) describes a
catheter for carrying stents including a stent positioner. U.S.
Pat. No. 6,143,016 to Bleam et al. describes a stent delivery
sheath. U.S. Pat. No. 5,807,398 to Shaknovich describes a shuttle
stent delivery catheter. U.S. Pat. Nos. 5,571,086 (Kaplan et al.)
and 5,776,141 (Klein et al.) describe an expandable sleeve for
placement over a balloon catheter for the delivery of one or two
stent structures to the vasculature. U.S. Pat. No. 5,697,948 to
Marin et al. describes a catheter for delivering stents covered by
a sheath. Patent application serial numbers 2003/0139797 (Johnson)
and 2003/0114919 (McQuiston) describe covered segmented stents.
BRIEF SUMMARY OF THE INVENTION
[0010] Devices and methods of the present invention provide for
delivering multiple stents or stent segments into a body lumen,
such as a blood vessel. Typically, devices include a catheter
having an expandable member with multiple stent segments mounted at
fixed positions thereon. By "fixed positions," it is meant that the
stent segments are not axially slidable, or are slidable only a
limited distance, along the expandable member. In alternative
embodiments, self-expanding stent segments may be used without an
expandable member.
[0011] Stent segments are deployed from the catheter by moving at
least one sheath overlying the expandable member to allow selected
length(s) of the balloon to expand, thus permitting one or more
individual stent segments or one or more groups of stent segments
to be deployed at one time. In some embodiments, two sheaths are
used or the expandable balloon is retracted within the catheter to
allow for multiple inflations and deflations of the balloon to
deploy subsequent stent segments. By mounting stent segments to an
expandable member at fixed positions, sliding advancement of stents
along the member is avoided, thus enhancing accuracy and efficiency
of stent deployment and preventing damage to the balloon or stent
coatings.
[0012] In one aspect of the present invention, a stent delivery
device for delivering a plurality of stent segments to a treatment
site includes: a catheter shaft having a proximal end and a distal
end; an expandable member coupled with the catheter shaft near the
distal end; a plurality of stent segments mounted on the expandable
member; and at least a first axially movable sheath disposed over
at least part of the catheter shaft, the expandable member and the
stent segments. The first sheath is adapted to constrain expansion
of a first portion of the expandable member and stent segments
thereon while allowing expansion of a second portion of the
expandable member and stent segments thereon. In some embodiments,
each of the plurality of stent segments is spaced apart from
adjacent stent segments, so that each stent segment can be expanded
by the expandable member without interfering with adjacent stent
segments.
[0013] Some embodiments further include at least a second axially
movable sheath disposed over part of the catheter shaft, the
expandable member and the stent segments. In such embodiments, the
first sheath is disposed proximally along the catheter shaft
relative to the second sheath, and the first and second sheaths are
adapted to allow expansion and deployment of at least one stent
segment between the sheaths. In some embodiments, for example, the
second sheath may be movable distally to allow for deployment of at
least one stent segment and proximally to constrain a portion of
the expandable member from which at least one stent segment has
been deployed. For example, the first sheath may be retracted to
allow deployment of one or more stent segments, the second sheath
may then be retracted to constrain the portion of the expandable
member from which the first stent segments were deployed, the first
sheath may be retracted to deploy one or more additional segments,
and so on.
[0014] As an alternative to a second sheath, in one embodiment the
stent delivery device includes an inner shaft slidably disposed
within the catheter shaft. In this embodiment, the expandable
member has a distal end coupled with the inner shaft for retracting
relative to the catheter shaft a portion of the expandable member
from which at least one stent segment has been deployed. Thus, as
stent segments are deployed, the portion of the balloon from which
they have been deployed is retracted within the catheter body.
[0015] In another aspect of the invention, a stent delivery device
for delivering a plurality of stent segments to a treatment site
comprises: a catheter shaft having a proximal end and a distal end;
an expandable member coupled with the catheter shaft near the
distal end; a plurality of stent segments mounted on the expandable
member; at least one axially movable sheath disposed over at least
part of the catheter shaft, the expandable member and the stent
segments, wherein the sheath is adapted to constrain expansion of a
first portion of the expandable member and stent segments thereon
while allowing expansion of a second portion of the expandable
member and stent segments thereon; and an inner shaft slidably
disposed within the catheter shaft. In this embodiment, as just
described, the expandable member includes a distal end coupled with
the inner shaft for retracting relative to the catheter shaft a
portion of the expandable member from which at least one stent
segment has been deployed.
[0016] In another aspect of the invention, an interventional
catheter device includes: a catheter shaft having a proximal end
and a distal end; an expandable member coupled with the catheter
shaft near the distal end; a distal sheath axially movable relative
to the expandable member and positionable over at least a distal
portion thereof; and a proximal sheath axially movable relative to
the expandable member and the distal sheath and positionable over
at least a proximal portion of the expandable member. The distal
and proximal sheaths are axially positionable to expose a selected
portion of the expandable member to allow expansion thereof while
covering another portion of the expandable member to constrain
expansion thereof.
[0017] Some embodiments also include a plurality of stents mounted
on the expandable member. In such embodiments, the distal sheath
may optionally be movable distally to allow for deployment of at
least one stent and proximally to constrain a portion of the
expandable member from which at least one stent has been deployed.
Optionally, at least a first of the stents may have a different
characteristic than at least a second of the stents, with the first
and second stent segments being mounted at different locations
along the expandable member. For example, the different stent
segments may have different diameters, shapes, lengths, geometries,
thicknesses, stiffness, stent materials, coating materials and/or
the like.
[0018] In some embodiments, the expandable member may be tapered
along its length, with the distal and proximal sheaths being
positionable to expose at least a first portion of the expandable
member having a first average cross-sectional diameter while
covering at least a second portion of the expandable member having
a second average cross-sectional diameter. In some embodiments,
each of the plurality of stents may comprise a plurality of stent
segments. Optionally, the length of each stent may be selected by
selecting the number of stent segments. In alternative embodiments,
the expandable member may include a first tapered portion having a
first average cross-sectional diameter and a second tapered portion
having a second average cross-sectional diameter, with the distal
and proximal sheaths being positionable to expose the first portion
while covering the second portion.
[0019] In yet another aspect of the present invention, a stent
delivery device for delivering a plurality of stent segments to a
treatment site comprises: a catheter shaft having a proximal end
and a distal end; a plurality of self-expanding stent segments
disposed on the catheter shaft; a distal sheath axially movable
relative to the stent segments and positionable over at least one
distal segment; and a proximal sheath axially movable relative to
the stent segments and the distal sheath and positionable over at
least one proximal segment. Here, the distal and proximal sheaths
are axially positionable to expose one or more selected stent
segments to allow expansion thereof while covering one or more
other stent segments to constrain expansion thereof.
[0020] In another aspect of the invention, a method for delivering
a plurality of stent segments to a treatment site includes:
positioning a distal portion of a stent delivery catheter device at
the treatment site; moving at least a first sheath of the catheter
device to expose at least part of an expandable member on the
catheter device and at least one of a plurality of stent segments
mounted on the expandable member; and expanding the expandable
member to deploy at least one of the plurality of stent segments at
the treatment site. Optionally, the method may further involve
moving the first sheath again to further expose the expandable
member to deploy at least one additional stent segment, moving the
first sheath a third time to further expose the expandable member
to deploy at least one additional stent segment, and so on. In some
embodiments, the additional stent segment(s) has a length different
than the at least one stent segment.
[0021] In some embodiments, the method further involves restraining
a first portion of the expandable member from which at least one
stent segment has been deployed while expanding a second portion of
the expandable member to deploy at least one additional stent
segment. In some embodiments, restraining the first portion of the
expandable member comprises moving a second sheath of the catheter
device over the first portion of the expandable member from which
at least one stent segment has been deployed. Alternatively,
restraining the first portion of the expandable member may involve
retracting a portion of the expandable member from which at least
one stent segment has been deployed within the catheter device.
[0022] In another aspect of the present invention, a method for
delivering a plurality of stent segments to treatment sites in a
body lumen involves: positioning a distal portion of a stent
delivery catheter device in the body lumen, the delivery catheter
having a plurality of stent segments mounted thereon; moving at
least a first sheath of the catheter device to deploy a first
selected number of stent segments at a first treatment site; and
moving at least the first sheath to deploy a second selected number
of stent segments at a second treatment site, wherein the first
selected number is different than the second selected number.
[0023] Optionally, such a method may further involve expanding a
first portion of an expandable member of the stent delivery device
to deploy the first selected number of stent segments and expanding
a second portion of the expandable member to deploy the second
selected number of stent segments. In some embodiments, the method
may also include moving a second sheath to constrain the first
portion of the expandable member before expanding the second
portion of the expandable member. In alternative embodiments, the
stent segments may be self-expanding so that moving the first
sheath exposes the self-expanding stents to allow them to expand
and deploy. Such methods may further include moving a second sheath
to selectively deploy the second selected number of stent segments.
In some embodiments, the first selected number of stents have a
first expanded diameter, and the second selected number of stents
have a second expanded diameter different than the first expanded
diameter. In other embodiments, the first selected number of stents
have a first geometry, and the second selected number of stents
have a second geometry different than the first geometry.
[0024] Further aspects of the nature and advantages of the
invention will become apparent from the detailed description below,
in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a perspective view of a stent delivery catheter
according to one embodiment of the invention, with a sheath
retracted and an expandable member inflated.
[0026] FIG. 2 is a side cross-section of a distal portion of a
stent delivery catheter according to one embodiment of the present
invention.
[0027] FIGS. 3A-3F are perspective-view diagrams of a distal
portion of a stent delivery catheter, demonstrating a method for
delivering multiple stent segments according to one embodiment of
the invention.
[0028] FIG. 4 is a side cross-section of a distal portion of a
stent delivery catheter according to another embodiment of the
present invention.
[0029] FIGS. 5A and 5B are perspective views of a distal end of a
stent delivery catheter having two sheaths, demonstrating how
stents of different lengths may be deployed according to one
embodiment of the invention.
[0030] FIGS. 6A-6C are perspective views of a distal end of a stent
delivery catheter having two sheaths, demonstrating how differently
configured stents may be deployed according to one embodiment of
the invention.
[0031] FIGS. 7A-7C are perspective views of a distal end of a stent
delivery catheter having two sheaths, demonstrating how different
stent may be deployed using different portions of a tapered
expandable member according to one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] A first embodiment of a stent delivery catheter according to
present invention is illustrated in FIG. 1. Stent delivery catheter
20 includes a catheter body 22 comprising an outer sheath 25
slidably disposed over an inner shaft 27. An expandable member 24,
such as an inflatable balloon (shown in an inflated configuration),
is mounted to inner shaft 27 and is exposed by retracting sheath 25
relative to inner shaft 27. A tapered nosecone 28, composed of a
soft elastomeric material to reduce trauma to the vessel during
advancement of the device, is mounted distally of expandable member
38. One or more stents 30, which preferably comprise a plurality of
separate or separable stent segments 32, are mounted at fixed
positions on expandable member 24 for expansion therewith. A
guidewire tube 34 is slidably positioned through a guidewire tube
exit port 35 in sheath 25 proximal to expandable member 24. A
guidewire 36 is positioned slidably through guidewire tube 34,
expandable member 24, and nosecone 28 and extends distally
thereof.
[0033] A handle 38 is mounted to a proximal end 23 of sheath 25 and
includes an actuator 40 slidably mounted thereto for purposes
described below. An adaptor 42 is mounted to the proximal end of
handle 38 and provides a catheter port 44 through which inner shaft
27 is slidably positioned. A flush port 48 is mounted to the side
of adaptor 42 through which a fluid such as saline can be
introduced into the interior of catheter body 22. An annular seal
(not shown) in catheter port 44 seals around inner shaft 27 to
prevent fluid from leaking through catheter port 44. Optionally, a
clamp (not shown) such as a threaded collar, can be mounted to
catheter port 44 to lock inner shaft 27 relative to handle 38.
[0034] Inner shaft 27 has a proximal end 50 to which is mounted an
inflation adaptor 52. Inflation adaptor 52 is configured to be
fluidly coupled to an inflation device 54, which may be any
commercially available balloon inflation device such as those sold
under the trade name "Indeflator.TM.," available from Advanced
Cardiovascular Systems of Santa Clara, Calif. Inflation adaptor 52
is in fluid communication with expandable member 24 via an
inflation lumen (described below) in inner shaft 27 to enable
inflation of expandable member 24.
[0035] FIG. 1 shows an embodiment of a catheter device having one
sheath. In alternative embodiments, two or more sheaths may be
used. For example, and with reference now to FIG. 2, in one
embodiment a distal portion of a stent delivery catheter 120 may
suitably include a distal sheath 126, a proximal sheath 125, an
outer expandable member shaft 127, an inner expandable member shaft
162, an expandable member 124, a distal sheath actuator 160 and a
nosecone 128. Multiple stent segments 132 may be disposed along
expandable member 124, and catheter 120 may be slidably disposed
over a guidewire 136. Of course, many other configurations and
combinations are encompassed within the scope of the present
invention as it is defined in the appended claims. For example, in
some embodiments, only one sheath is included. Other embodiments
may include modifications or additional features, such as those
described in U.S. patent application Ser. Nos. 10/412,714 (now U.S.
Pat. No. 7,137,993) and 10/637,713 (now U.S. Pat. No. 7,309,350),
which were previously incorporated by reference. Thus, stent
delivery catheter 120 in FIG. 2 is but one exemplary
embodiment.
[0036] That being said, proximal sheath 125 and distal sheath 126
are slidably disposed over expandable member 124 (and stent
segments 132 disposed thereon) when in an unexpanded configuration.
Distal sheath 126 is coupled with nosecone 128, and nosecone 128 is
coupled with distal sheath actuator 160 at attachment points 161
via any suitable mechanism, such as adhesives, welding, press
fitting or the like. These connections allow distal sheath actuator
160 to be used to axially move distal sheath 126 and nosecone 128
relative to the rest of catheter 120. For example, as will be
explained in more detail below, distal sheath 126 may be moved
distally to expose a portion of expandable member 124 and one or
more stent segments 132 disposed thereon. Distal sheath 126 may
also be positioned over expandable member 124 to constrain a
portion of expandable member 124 from which one or more stent
segments 132 have been deployed. Proximal sheath 125 typically
extends up to the proximal end of distal sheath 126 from the
proximal end (or nearly the proximal end) of catheter 120. Like
distal sheath 126, proximal sheath 125 is also slidably disposed
over expandable member 124. In various embodiments, proximal sheath
125 may be movable proximally, distally or both. For example,
proximal sheath may sometimes be retracted proximally to expose a
portion of expandable member 124 and one or more stent segments 132
between the two sheaths, but in some embodiments may also be
advanced distally to cover a selected portion of expandable member
124 and stent segments 132 thereon.
[0037] Both distal sheath 126 and proximal sheath may have any
suitable shape, length, cross-sectional diameter, material
thickness, and the like and may be made of any suitable material or
combination of materials. In one embodiment, for example, distal
sheath 126 may have a length sufficient to cover the entirety of
expandable member 124, in one embodiment being between about 15 cm
and about 35 cm. Proximal sheath 125 may have a length selected to
extend over the entirety of expandable member 124 as well, in one
embodiment being between about 100 cm and about 125 cm. Either
sheath may be constructed of any of a variety of biocompatible
materials, such as but not limited to a polymer such as PTFE, FEP,
polyimide, or Pebax, may be reinforced with a metallic or polymeric
braid to resist radial expansion of expandable member 124, and/or
the like.
[0038] Inner expandable member shaft 162 and outer expandable
member shaft 127 are coupled with expandable member 124 to form an
inflation lumen 166 that is in communication with the interior of
expandable member 124. Both inner shaft 162 and outer shaft 127 may
be formed of any suitable material(s), such as but not limited to a
polymer such as PTFE, FEP, polyimide, or Pebax, and may be
reinforced with a metallic braid for added radial strength and kink
resistance. In the proximal extremity of delivery catheter 120,
inner shaft 127 may comprise a similar polymer or a metal such as
stainless steel or Nitinol.
[0039] Expandable member 124 comprises an expandable balloon that
is joined to inner expandable member shaft 162 and outer expandable
member shaft 127. Expandable member 124 may be formed of a
semi-compliant polymer such as Pebax or Nylon. Distal sheath
actuator 160 passes through the interior of inner expandable member
shaft 162 and is mounted to nosecone 128 at one of the attachment
points 161, thereby providing a passage through catheter 20 through
which guidewire 136 may pass.
[0040] Stent segments 132 are mounted at fixed positions along
expandable member 124. In an exemplary embodiment, each stent
segment is about 2-8 mm in length, and up to 10-50 stent segments
may be positioned end-to-end in a line over expandable member 124.
In some embodiments, stent segments 132 are mounted to expandable
member 124 with an inter-segment spacing selected to allow
expansion of one segment while an adjacent segment is constrained
within one or both sheaths 125, 126. Alternatively, separate
spacing elements may be disposed between adjacent stent segments
132, the spacing elements being fixed with stent segments 132 on
expandable member 124. In some embodiments, such spacing elements
may be plastically deformable or self-expanding so as to be
deployable with stent segments 132 into the vessel. Alternatively,
spacing elements may be configured to remain on expandable member
124 following stent deployment. For example, such spacing elements
could comprise elastic rings which elastically expand with
expandable member 124 and resiliently return to their unexpanded
shape when expandable member 124 is deflated. In another
alternative embodiment, expandable member 124 could have ridges,
bumps or other surface features configured to maintain
inter-segment spacing.
[0041] Stent segments 132 are preferably constructed of a malleable
metal so as to be plastically deformable by expandable member 124
as they are expanded to the desired diameter in the vessel.
Alternatively, stent segments 132 may be formed of an elastic or
super elastic shape memory material such as Nitinol so as to
self-expand upon release into the vessel by retraction of one or
both sheaths 125, 126. Stent segments 132 may also be composed of
polymers or other suitable biocompatible materials. In
self-expanding embodiments, expandable member 124 may also be used
for predilatation of a lesion prior to stent deployment or for
augmenting the expansion of the self-expanding stent segments.
[0042] In some embodiments, stent segments 132 are coated,
impregnated, infused or otherwise coupled with one or more drugs
that inhibit restenosis, such as Rapamycin, Everolimus, Paclitaxel,
analogs, prodrugs, or derivatives of Rapamycin, Everolimus or
Paclitaxel, or other suitable agent(s), preferably carried in a
bioerodable polymeric carrier. Alternatively, stent segments 132
may be coated with other types of drugs or therapeutic materials
such as antibiotics, thrombolytics, anti-thrombotics,
anti-inflammatories, cytotoxic agents, anti-proliferative agents,
vasodilators, gene therapy agents, radioactive agents,
immunosuppressants, chemotherapeutics and/or stem cells. Such
materials may be coated over all or a portion of the surface of
stent segments 132, or stent segments 132 may include apertures,
holes, channels, or other features in which such materials may be
deposited.
[0043] Stent segments 132 may have a variety of configurations,
including those described in copending application Ser. Nos.
60/440,839, filed Jan. 17, 2003 (Attorney Docket No. 21629-000500),
which is hereby incorporated fully by reference, and 10/637,713
(now U.S. Pat. No. 7,309,350), which was previously incorporated by
reference. Stent segments 132 are preferably completely separate
from one another without any interconnections, but alternatively
may have couplings between two or more adjacent segments which
permit flexion between the segments. As a further alternative, one
or more adjacent stent segments 132 may be connected by separable
or frangible couplings that are separated prior to or upon
deployment, as described in copending application Ser. No.
10/306,813, filed Nov. 27, 2002 (Attorney Docket No. 21629-000320),
which is incorporated herein by reference.
[0044] With one or both sheaths 125, 126 retracted and/or advanced
a desired distance, expandable member 124 is allowed to expand when
inflation fluid is delivered through inflation lumen 166, thereby
expanding a desired number of stent segments 132 exposed between
proximal sheath 125 and distal sheath 126. The remaining portion of
expandable member 124 and the remaining stent segments 132 within
sheaths 125, 126 are constrained from expansion by sheaths 125,
126.
[0045] Referring now to FIGS. 3A through 3F, one embodiment of a
method for using a stent delivery catheter 220 similar to the one
shown in FIG. 2 is demonstrated in a series of diagrams. In FIG.
3A, catheter 220 is advanced to a location in a blood vessel V for
treating a first occlusion O1 with one or more stents or stent
segments. Catheter device 220 generally includes a distal sheath
226, a proximal sheath 225 and a nosecone 228 and is advanceable
over a guidewire 236.
[0046] In FIG. 3B, distal sheath 226 is advanced distally (shown by
horizontal arrows) to expose a portion of an expandable member 224
having length suitable for occlusion O1 and stent segments 232
disposed thereon. In an alternative embodiment of the method,
catheter 220 may be positioned such that proximal sheath 225 may be
retracted to expose the portion of expandable member 224 and
corresponding stent segments 232. Next, as shown in FIG. 3C,
expandable member 224 may be expanded to expand stent segments 232,
to contact stent segments 232 with the first occlusion O1.
Expandable member 224 may then be deflated (not shown), leaving
stent segments in the vessel V. As shown in FIG. 3D, distal sheath
226 may then be retracted (horizontal arrows) to cover and
constrain the portion of expandable member 224 from which stent
segments 232 have been deployed.
[0047] As also shown in FIG. 3D, catheter 220 may next be
repositioned in the vessel V for treatment of a second occlusion
O2. Proximal sheath 225 may be retracted, as shown in FIG. 3E, to
expose a more proximal portion of expandable member 224 having a
desired length for occlusion O2, while distal sheath 226 constrains
the portion from which stent segments 232 have been deployed. When
expandable member 224 is expanded, as in FIG. 3F, the constraint by
distal sheath 226 prevents the portion of expandable member 224
that no longer holds stents from expanding, which might disrupt
already-placed stents, damage expandable member 224, damage the
vessel V and/or the like. The exposed portion of expandable member
224 expands stent segments 232 mounted thereon in contact with the
second occlusion O2. Again, expandable member 224 may be deflated,
distal sheath 226 may be retracted, and additional stent segments
232 may be deployed. Alternatively, stent delivery catheter may be
removed from the vessel V. Using methods and devices such as those
just described enhances delivery of multiple stents or stent
segments of various lengths to more than one occlusion, lesion,
treatment site or the like.
[0048] Obviously, the above description is but one of a number of
possible embodiments of methods for delivering stents or stent
segments according to the invention. Steps may be modified, deleted
or added, the order of steps may be changed, and/or the like,
without departing from the scope of the invention. In some
embodiments, for example, only one sheath is used. In such
embodiments, all stent segments that are desired to be deployed may
be deployed with one expansion of the expandable member, for
example. In other embodiments using two sheaths, the way or order
in which the sheaths are moved relative to one another and to other
parts of the catheter device may be altered as desired. Therefore,
the foregoing example is provided for exemplary purposes only and
should not be interpreted to limit the scope of the present
invention.
[0049] Referring now to FIG. 4, an alternative embodiment of a
stent delivery catheter device 320 may also enhance serial stent
deployment while protecting an expandable member 324 of the device.
In this embodiment, the distal end of expandable member 324 is
coupled to an inner balloon shaft 362 at a first attachment point
372a, and the proximal end of expandable member 324 is coupled to
an outer balloon shaft 327 at a second attachment point 372b.
Between inner shaft 362 and outer shaft 327 is an axial support
shaft 370, and between axial support shaft 370 and outer shaft 327
is an inflation lumen 366. A sheath 325 is slidably disposed over
balloon shaft 327, enabling the length of the expandable portion of
the balloon to be changed. As stent segments 332 are deployed from
the distal portion of expandable member 324, inner balloon shaft
362 may be retracted proximally within axial support shaft 370
(horizontal lines) to pull the distal portion of expandable member
324 within the axial support shaft 370 (curved arrows). Thus,
multiple stents or stent segments 332 may be deployed at multiple
locations, multiple lesions or the like by inflating and deflating
expandable member 324 multiple times, while constraining the
portion of expandable member 324 from which stent segments 332 have
been deployed.
[0050] FIGS. 5A and 5B demonstrate one way in which a stent
delivery catheter device 420 of the present invention may be used
to deliver stents having different lengths and/or different numbers
of stent segments 432. In FIG. 5A, a distal sheath 426 and a
proximal sheath 425 are positioned to expose a first portion of an
expandable member 424a and a stent having a first length. In FIG.
5B, distal sheath 426 and proximal sheath 425 are positioned to
expose a second, shorter portion of expandable member 424b and a
shorter stent. Of course, any number of different stents or stent
segments may be mounted in fixed positions on expandable member 424
and proximal and distal sheaths 425, 426 may be positioned in any
number of combinations to allow a physician to places various
stents/segments at various locations to treat multiple lesions.
[0051] Referring now to FIGS. 6A-6C, embodiments of a stent
delivery catheter device 520 may also be used to deliver multiple
different types of stents having different characteristics within
the same vessel or during the same procedure. For example, if
stents having multiple different configurations are mounted at
different fixed positions along an expandable member 524, a distal
sheath 426 and a proximal sheath 425 may be positioned variously to
allow expansion and deployment of the different stents at different
locations. In FIG. 6A, for example, sheaths 425, 426 may be moved
to expose a first portion of expandable member 524a to expose a
first stent 532a having a zig-zag configuration. As in FIG. 6B,
sheaths 425, 426 may be moved to expose a second portion of
expandable member 524b, to deploy a second stent 432b with a
"closed-cell" or honeycomb configuration. A third portion of
expandable member 524c may then be exposed to deploy a third stent
having multiple stent segments 532c. Again, any number of
combinations of stents, stent positions and the like may be used.
Stents having various lengths, diameters, strut thicknesses,
geometries, materials, stiffness and coatings may be mounted at
different locations along the expandable member allowing the user
to select the ideal stent for each lesion treated.
[0052] With reference now to FIGS. 7A-7C, one embodiment of a stent
delivery catheter device 620 may include a tapered expandable
member 624 having a decreasing cross-sectional diameter from its
proximal end to its distal end. Such tapered expandable members are
disclosed in co-pending U.S. patent application Ser. No. 10/458,062
now U.S. Pat. No. 7,241,308 (Attorney Docket No. 021629-001800US),
the full disclosure of which is hereby incorporated by reference.
Using a distal sheath 626 and a proximal sheath 625, the entire
expandable member 624 may be exposed or portions may be selectively
exposed to allow expansion and delivery of a selected number of
stents or stent segments 632 to a selected diameter or taper. In
FIG. 7A, for example, a long portion of expandable member 624a is
exposed to allow deployment of a first number of stent segments
632a. In FIG. 7B, a shorter portion of expandable member 624b is
exposed to deploy a different selected number of stent segments
632b, the exposed portion being closer to the proximal end of
expandable member 624 than the distal end and having a relatively
larger expanded diameter. In FIG. 7C, a different portion of
expandable member 624c is exposed to allow deployment of yet
another set of stent segments 632c having a smaller expanded
diameter. Using such an embodiment allows a physician to choose
different portions of a tapered expandable member 624 for deploying
stent segments 632, each portion having a different expanded
diameter. This may be advantageous, for example, in placing
multiple stents or stent segments in a tapered blood vessel or a
vessel having varying diameters along its length at a treatment
site. Further, the taper angle of the expandable member may be
different at different axial locations on the expandable member,
allowing the physician to select the ideal taper for the vessel
being treated.
[0053] The above-described concepts of utilizing a tapered balloon
having either constant or various taper angles with one or more
sheaths to select a desired taper can also be applied to dilatation
catheters for performing balloon angioplasty. Such catheters may be
utilized in a manner similar to that shown in FIGS. 7A-7C, without
the use of stents or stent segments on the expandable member.
Moreover, a combination dilatation/stenting catheter is also within
the scope of the invention, wherein a first portion of the balloon
(usually near the distal end) has no stents disposed around it and
is configured for dilatation, while a second portion of the balloon
has stents positioned over it for expansion. In this way, the first
portion of the balloon may be exposed for dilatation of a lesion
while the second portion is covered by a sheath. Following
dilatation, the first portion may be covered by a sheath while the
second portion is expanded to deploy the stents in the lesion.
Advantageously, the lengths of both the first and second portion
may be adjusted so as to tailor the dilatation balloon and the
stent to the size of the lesion treated.
[0054] Although the above is complete description of the preferred
embodiments of the invention, various alternatives, additions,
modifications and improvements may be made without departing from
the scope thereof, which is defined by the claims.
* * * * *