U.S. patent application number 11/627096 was filed with the patent office on 2008-04-24 for implantable 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 | 20080097574 11/627096 |
Document ID | / |
Family ID | 34520996 |
Filed Date | 2008-04-24 |
United States Patent
Application |
20080097574 |
Kind Code |
A1 |
Andreas; Bernard ; et
al. |
April 24, 2008 |
IMPLANTABLE STENT DELIVERY DEVICES AND METHODS
Abstract
Stent delivery devices include at least one implantable stent
carrier and/or membrane for carrying multiple stents or stent
segments over an expandable member. At least a portion of the
implantable carrier is expandable by the expandable member to
deploy the portion of the carrier and one or more stent segments
disposed thereon. A sheath may be retracted to expose and expand a
distal portion of the expandable member to expand and deploy a
distal portion of the carrier and the stent segment(s) disposed
thereon. Stent delivery devices and methods provide enhanced
delivery of multiple stents or stent segments by delivering the
segments while coupled with one or more implantable carriers and/or
membranes that are typically flexible and dividable.
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: |
34520996 |
Appl. No.: |
11/627096 |
Filed: |
January 25, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10687532 |
Oct 15, 2003 |
7192440 |
|
|
11627096 |
Jan 25, 2007 |
|
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Current U.S.
Class: |
623/1.12 ;
623/1.11; 623/1.42 |
Current CPC
Class: |
A61F 2/958 20130101;
A61F 2002/826 20130101; A61F 2250/0071 20130101; A61F 2/966
20130101; A61M 2025/0681 20130101 |
Class at
Publication: |
623/001.12 ;
623/001.11; 623/001.42 |
International
Class: |
A61F 2/84 20060101
A61F002/84; A61F 2/82 20060101 A61F002/82 |
Claims
1. A delivery system comprising: a flexible catheter shaft; a
plurality of radially-expandable, tubular stent segments releasably
coupled to the catheter shaft; an implantable carrier extending
across at least two adjacent stent segments; and a dividing element
coupled to the catheter shaft and adapted to divide the implantable
carrier between the adjacent stent segments, wherein a first of the
tubular stent segments may be expanded and released from the
catheter shaft with a first portion of the implantable carrier
while a second of the stent segments is retained unexpanded on the
catheter shaft with a second portion of the implantable
carrier.
2. A delivery system as in claim 1, further comprising an
expandable member coupled near a distal end of the catheter
shaft.
3. A delivery system as in claim 2, wherein the implantable carrier
is slidably disposed over the expandable member.
4. A delivery system as in claim 1, wherein the implantable carrier
is slidably disposed over the catheter shaft.
5. A delivery system as in claim 1, further comprising a carrier
shaft coupled with the implantable carrier and disposed over the
catheter shaft proximal to the implantable carrier for advancing
the carrier distally.
6. A delivery system as in claim 1, further comprising a sheath,
the sheath slidably disposed over the implantable carrier to
constrain expansion of a proximal portion of the expandable member
while allowing expansion of a distal portion of the expandable
member.
7. A delivery system as in claim 6, wherein the dividing element is
disposed near a distal end of the sheath.
8. A delivery system as in claim 6, wherein the dividing element
comprises a sharpened edge disposed circumferentially about an
inner surface of the sheath at a distal end of the sheath.
9. A delivery system as in claim 8, further including a protective
member disposed between the sharpened edge and the catheter shaft
expandable member to prevent damage to the catheter shaft by the
sharpened edge.
10. A delivery system as in claim 1, wherein the dividing element
acts as a valve member to provide control of a number of stents
segments delivered by the device.
11. A delivery system as in claim 2, wherein expanding the
expanding member presses the implantable carrier against the
dividing element to divide the distal portion of the carrier from a
proximal portion of the carrier.
12. A delivery system as in claim 1, wherein the implantable
carrier comprises at least one dividable connection between at
least the distal portion of the carrier and a proximal portion of
the carrier.
13. A delivery system as in claim 12, wherein the at least one
dividable connection is preformed in the carrier.
14. A delivery system as in claim 12, wherein the at least one
dividable connection comprises multiple dividable connections
between multiple carrier portions.
15. A delivery system as in claim 12, wherein each of the at least
one dividable connections comprises at least one of perforations,
frangible connections and an area of material along the carrier
that is thinner than immediately adjacent areas of material.
16. A delivery system as in claim 1, wherein the implantable
carrier comprises at least one material selected from the group
consisting of a polymer, a metal, a metal alloy, a woven polyester,
polytetrafluoroethylene, a ceramic, human tissue and animal
tissue.
17. A delivery system as in claim 1, wherein the implantable
carrier comprises at least one biodegradable or bioresorbable
material.
18. A delivery system as in claim 1, wherein the implantable
carrier comprises at least one pharmacological or biological
agent.
19. A delivery system as in claim 18, wherein the pharmacological
agent is selected from the group consisting of Rapamycin,
Paclitaxel, Rapamycin or Paclitaxel analogs, Everolimus and
derivatives thereof, prodrugs, or derivatives, antibiotics,
thrombolytics, anti-thrombotics, anti-inflammatories, cytotoxic
agents, anti-proliferative agents, vasodilators, gene therapy
agents, radioactive agents, immunosuppressants, chemotherapeutics
and stem cells.
20. A delivery system as in claim 1, wherein the implantable
carrier is non-porous so as to act as a vascular graft.
21. A delivery system as in claim 1, wherein the implantable
carrier comprises a solid tubular wall.
22. A delivery system as in claim 1, wherein the implantable
carrier comprises a tubular mesh.
23. A delivery system as in claim 1, wherein the implantable
carrier comprises a tubular scaffold.
24. A delivery system as in claim 1, wherein the implantable
carrier comprises a helical coil.
25. A delivery system as in claim 1, wherein the implantable
carrier comprises multiple axial beams.
26. A delivery system as in claim 1, wherein the plurality of stent
segments are fixedly disposed along the carrier.
27. A delivery system as in claim 1, further comprising at least
one membrane coupled with at least one of the plurality of stent
segments.
28. A delivery system as in claim 27, wherein the at least one
membrane is permeable.
29. A delivery system as in claim 27, wherein the at least one
membrane is impermeable.
30. A delivery system as in claim 27, wherein the at least one
membrane comprises a continuous membrane coupled with the plurality
of stent segments.
31. A delivery system as in claim 27, wherein the at least one
membrane comprises a plurality of membranes, each membrane coupled
with at least one of the plurality of stent segments.
32. A delivery system as in claim 27, wherein the at least one
membrane comprises a plurality of membranes, each membrane coupled
with two or more of the plurality of stent segments.
33. A delivery system as in claim 27, wherein the at least one
membrane comprises at least one biodegradable or bioresorbable
material.
34. A delivery system as in claim 27, wherein the at least one
membrane comprises at least one pharmacological or biological
agent.
35. A delivery system as in claim 34, wherein the pharmacological
agent is selected from the group consisting of Rapamycin,
Paclitaxel, Rapamycin or Paclitaxel analogs, prodrugs, or
derivatives, antibiotics, thrombolytics, anti-thrombotics,
anti-inflammatories, cytotoxic agents, anti-proliferative agents,
vasodilators, gene therapy agents, radioactive agents,
immunosuppressants, chemotherapeutics and stem cells.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 10/687,532 (Attorney Docket No.
021629-002100US), filed Oct. 15, 2003, the full disclosure of which
is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to medical devices
and methods. More particularly, the invention relates to apparatus
and methods for independently delivering segmented stents or stent
grafts within a body lumen.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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 (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 (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.
[0008] 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,
flexibility of a stent is important in stenting long lesions,
tortuous vessels, lesions at vessel branches and the like. The
above referenced patent applications disclose the use of segmented
stents with separate or separable segments to provide highly
flexible stents of selectable length. However, in some cases it may
be advantageous to use segments that are coupled together during
deployment to maintain segment alignment and prevent mobilization
of the segments. It may also be beneficial to use interconnected
stents to form a tubular passage, such as a graft.
[0009] As another example, many balloon-expandable stents are
currently delivered by devices in which the stents are in direct
contact with the balloon or other expandable member. If such stents
are pushed or otherwise advanced along the expandable member in its
deflated state, the direct contact between the stents and the
balloon during advancement may cause damage to the balloon and/or
to the stents or their coatings. A balloon or other expandable
member may also interfere with stent advancement, especially after
the balloon has been inflated and deflated multiple times and,
thus, becomes somewhat flaccid and/or deformed. Thus, stent
delivery devices in which the stents directly contact the
expandable member may lead to increased risk of balloon or stent
damage, increased general wear and tear, difficult stent
advancement along the delivery device, and less precise stent
placement.
[0010] Therefore, a need exists for improved stent delivery devices
and methods. Ideally, such devices and methods would provide
flexible coupling of stent segments during deployment of the
segments. Also ideally, such devices and methods would at least
reduce direct contact between stents and the expandable member of
the delivery device to reduce damage to the stents and expandable
member and to facilitate stent placement. At least some of these
objectives will be met by the present invention.
[0011] 2. Description of the Background Art
[0012] U.S. patent application Ser. Nos. 10/412,714 and 10/637,713,
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 Beam 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
[0013] Stent delivery devices and methods of the present invention
provide for delivering a plurality of stents, a segmented stent or
stent grafts in body lumens. Generally, devices of the invention
include a stent delivery catheter having at least one implantable
carrier and/or membrane for carrying segmented stents. The carrier
or membrane allows multiple segments of a stent to be coupled
together flexibly during deployment. In some embodiments, the
carrier or membrane helps prevent damage to stent segments or to an
expandable member caused by contact between the segments and the
member. In some embodiments, stent segments and the carrier(s)
and/or membrane(s) are deployed from the catheter by retracting a
sheath to expose and expand an expandable balloon. The exposed,
expanded balloon expands a portion of the implantable carrier or
membrane and one or more stent segments disposed thereon, thus
deploying the carrier and the segments. In some embodiments, the
sheath may subsequently be drawn proximally to further expose and
expand the balloon, thus deploying additional portion(s) of the
carrier and one or more additional stent segments disposed
thereon.
[0014] Various embodiments of the invention may be configured to
individually and/or selectively deliver multiple stents, multiple
stent segments of one stent, multiple stent grafts or stent graft
segments, or the like. Although the following description often
refers to delivery of "stent segments," this phrase should not be
interpreted to limit the scope of the invention in any way.
Generally, devices and methods of the invention may be used to
delivery any suitable luminal prosthesis, multiple prostheses, or
multiple prosthesis segments to a body lumen, and are thus not
limited to delivery of one stent, segmented stents or the like.
[0015] In one aspect of the present invention, a stent delivery
device for delivering a plurality of stents or 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; at least one implantable carrier
disposed over the expandable member; a plurality of stent segments
disposed along the carrier; and a sheath slidably disposed over the
implantable carrier to constrain expansion of a proximal portion of
the expandable member while allowing expansion of a distal portion
of the expandable member. The expanded distal portion of the
expandable member expands a distal portion of the implantable
carrier and at least one stent segment disposed thereon to deliver
the distal portion of the implantable carrier and the at least one
stent segment.
[0016] In some embodiments, the implantable carrier is slidably
disposed over the expandable member, while in other embodiments,
the carrier may have a fixed position. In slidable embodiments, the
catheter device may further include a carrier shaft coupled with
the implantable carrier and disposed over the catheter shaft
proximal to the implantable carrier for advancing the carrier
distally.
[0017] Optionally, the sheath may further include at least one
carrier cutting member disposed to cut the implantable carrier at
one or more locations between the stent segments. For example, the
carrier cutting member may comprise a sharpened edge disposed
circumferentially about an inner surface of the sheath at a distal
end of the sheath. Such embodiments may also include a protective
member disposed between the sharpened edge and the expandable
member to prevent damage to the expandable member by the sharpened
edge. In some embodiments, the carrier cutting member may act as a
valve member to provide control of a number of stents segments
delivered by the device. Also in some embodiments, expanding the
expanding member may press the implantable carrier against the
carrier cutting member to divide the distal portion of the carrier
from a proximal portion of the carrier.
[0018] In some embodiments, the implantable carrier includes at
least one dividable connection between at least the distal portion
of the carrier and a proximal portion of the carrier. In fact, some
embodiments may include multiple dividable connections between
multiple carrier portions. Such dividable connections may comprise,
for example, perforations, frangible connections, an area of
material along the carrier that is thinner than immediately
adjacent areas of material, and/or the like. Such connections may
be configured to separate or break upon expansion of the expandable
member, with or without the use of a cutting member on the sheath.
Some of such connection may remain intact following deployment and
may remain permanently connected, or may degrade and separate over
time.
[0019] The carrier itself may be made of any suitable material or
combination of materials, such as but not limited to polymers,
metals, metal alloys, woven polyesters, polytetrafluoroethylene,
ceramics, human tissues, animal tissues and/or the like. In some
embodiments, the implantable carrier may include at least one
biodegradable or bioresorbable material, or may be made wholly of
biodegradable or bioresorbable materials. Also in some embodiments,
the implantable carrier may include at least one pharmacological or
biological agent, such as but not limited to Rapamycin, Paclitaxel,
Rapamycin or Paclitaxel analogs, prodrugs, or derivatives,
Everolimus and derivatives thereof, antibiotics, thrombolytics,
anti-thrombotics, anti-inflammatories, cytotoxic agents,
anti-proliferative agents, vasodilators, gene therapy agents,
radioactive agents, immunosuppressants, chemotherapeutics, stem
cells and/or the like. In some embodiments, the implantable carrier
is non-porous so as to act as a vascular graft, while in other
embodiments the carrier is partially or completely porous. In
various embodiments, the implantable carrier may comprise a solid
tubular wall, a tubular mesh, a tubular scaffold, a helical coil,
multiple axial beams or the like. The stent segments may be either
fixedly or slidably disposed along the carrier, according to
various embodiments.
[0020] In some embodiments, the stent delivery device may further
include at least one membrane coupled with at least one of the
stent segments. In some embodiments, the membrane comprises a
continuous membrane coupled with a plurality of stent segments.
Alternatively, a plurality of membranes may be coupled with the
stent segments such that each membrane is coupled with one of the
stent segments or each membrane is coupled with two or more
segments. The membrane may be either impermeable or impermeable and
may be made of any suitable material or materials. For example, the
membrane may comprise at least one biodegradable or bioresorbable
material. The membrane may also include at least one
pharmacological or biological agent, such as but not limited to
Rapamycin, Paclitaxel, Rapamycin or Paclitaxel analogs, prodrugs,
or derivatives, antibiotics, thrombolytics, anti-thrombotics,
anti-inflammatories, cytotoxic agents, anti-proliferative agents,
vasodilators, gene therapy agents, radioactive agents,
immunosuppressants, chemotherapeutics, stem cells and/or the
like.
[0021] In another aspect of the present invention, a stent delivery
device for delivering a plurality of stents or 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; at least one implantable membrane
disposed over the expandable member; a plurality of stent segments
disposed along the membrane; and a sheath slidably disposed over
the implantable membrane to constrain expansion of a proximal
portion of the expandable member while allowing expansion of a
distal portion of the expandable member. The expanded distal
portion of the expandable member expands a distal portion of the
implantable membrane and at least one stent segment disposed
thereon to deliver the distal portion of the implantable membrane
and the at least one stent segment. The membrane or membranes may
have any of the characteristics of the membranes described
above.
[0022] In yet another aspect of the invention, a method for
delivering a stent having a plurality of stent segments to a
treatment site involves positioning a distal portion of a stent
delivery catheter device at the treatment site, the stent delivery
catheter having an implantable carrier and a plurality of stent
segments disposed along the carrier, and expanding a distal portion
of the implantable carrier and at least one distal stent segment
disposed thereon to deploy the distal portion of the carrier and
the at least one distal stent segment while constraining a proximal
portion of the implantable carrier and at least one proximal stent
segment disposed thereon.
[0023] In some embodiments, expanding the distal portion of the
carrier while constraining the proximal portion comprises moving a
sheath proximally to expose an expandable member to allow it to
expand against the distal portion of the implantable carrier and
the at least one distal stent segment. The method may further
include moving the sheath proximally to further expose the
expandable member to allow it to expand against an additional
portion of the implantable carrier and at least one stent segment
disposed thereon. This process may be repeated as many times as
desired to deploy additional portions of the carrier and additional
stent segments. Optionally, the method may also include advancing
the implantable carrier in a distal direction along the catheter
device, using a carrier shaft located proximal to the carrier on
the catheter device. Also optionally, the method may include
cutting the implantable carrier with a cutting member to deploy the
distal implantable carrier segment.
[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 an embodiment of the invention, with a distal portion
of the catheter device shown in cross section with a sheath
retracted and an expandable member inflated.
[0026] FIG. 2A is a side view of a distal portion of a stent
delivery catheter having an implantable, dividable carrier and
stent segments, according to one embodiment of the present
invention.
[0027] FIG. 2B is a side cross-sectional view of the distal portion
of the stent delivery catheter shown in FIG. 2A.
[0028] FIGS. 3A-3C are side views of various embodiments of an
implantable, dividable stent carrier, according to various
embodiments of the present invention.
[0029] FIG. 4A-4C demonstrate a method for delivering a plurality
of stent segments and an implantable carrier segment at a treatment
site, according to one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Stent delivery devices of the present invention generally
include at least one implantable stent carrier and/or membrane for
carrying multiple stents or stent segments over an expandable
member. At least a portion of the implantable carrier is expandable
by the expandable balloon to deploy the portion of the carrier and
one or more stent segments disposed thereon. A sheath, typically
disposed over the carrier but alternatively disposed between the
carrier and the expandable member, may be retracted to expose and
expand a distal portion of the expandable member to expand and
deploy a distal portion of the carrier and stent segment(s)
disposed thereon. In various alternative embodiments, the carrier
may be either slidably or fixedly disposed over the expandable
member. In slidable embodiments, the device may further include a
carrier shaft disposed proximally of the carrier for advancing the
carrier distally over the expandable member. Stent delivery devices
and methods of the invention provide enhanced delivery of multiple
stents or stent segments by delivering the segments while connected
to an implantable carrier and/or membrane that is typically
flexible and dividable to deploy a desired length of carrier and
associated number of stent segments.
[0031] Various embodiments of the invention may be configured to
individually and/or selectively deliver multiple stents, multiple
stent segments of one stent, multiple stent grafts or stent graft
segments, or the like. Although the following description often
refers to delivery of "stent segments," this phrase should not be
interpreted to limit the scope of the invention in any way.
Generally, devices and methods of the invention may be used to
delivery any suitable luminal prosthesis, multiple prostheses, or
multiple prosthesis segments to a body lumen, and are thus not
limited to delivery of one stent, segmented stents or the like. For
example, instead of delivering multiple segments of one segmented
stent, devices and methods of the invention may be used to deliver
multiple stents. Any other suitable configuration is
contemplated.
[0032] Referring now to FIG. 1, a stent delivery catheter 20 is
shown. The catheter 20 is similar to a stent delivery catheter
described in U.S. patent application Ser. No. 10/637,713,
previously incorporated by reference, but includes an implantable
carrier 21 along which a stent 30 having multiple stent segments 32
is disposed. Generally, stent delivery catheter 20 may suitably
include a catheter body 22 comprising a sheath 25 slidably disposed
over a carrier shaft 61 and an expandable member shaft 27. An
expandable member 24, preferably an inflatable balloon (shown in
inflated configuration), is mounted to expandable member shaft 27
and is exposed by retracting sheath 25 relative to shaft 27 and
expandable member 24. Alternatively, expandable member 24 could be
any one of a variety of other mechanically, hydraulically,
electrically, or otherwise expandable structures known in the
intraluminal catheter arts, such as expandable braids, expandable
cages, expandable Mallecott structures, self-expanding structures
(including shape memory cages), and the like. A tapered nosecone
28, composed of a soft elastomeric material to reduce trauma to the
vessel during advancement of the device, may be mounted distally of
expandable member 34.
[0033] Stent 30, which preferably comprises a plurality of separate
or separable stent segments 32, is disposed on implantable carrier
21, which in turn is disposed on expandable member 24 for expansion
therewith, typically being coaxially and slidably received over
expandable member shaft 27. 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. Other designs where a
guidewire is received through the entire length of shafts 27 and 61
are also contemplated within the present invention.
[0034] A handle or hub 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
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 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 shaft 27 relative to handle 38. While adaptor 42 is
shown separately from handle 38, the structures could be made
integral to each other as well.
[0035] Expandable member shaft 27 has a proximal end 50 to which is
mounted an inflation adaptor 52 (which could also be formed
integrally with handle 38). 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 in shaft 27 to enable inflation of expandable
member 24. For further description of devices and methods for
delivering distributed stents, as well as various embodiments of
stents themselves, reference may be made to U.S. patent application
Ser. Nos. 10/412,714 and 10/637,713, previously incorporated by
reference.
[0036] As mentioned above and described in more detail below, the
configuration of stent delivery catheter 20 make take any of a
number of alternative forms. For example, implantable carrier 21
may be disposed within sheath 25 and around expandable member 24.
In an alternative embodiment, implantable carrier 21 may be
slidably or fixedly disposed over sheath 25. Implantable carrier 21
may comprise a relatively long tubular member, perhaps extending
much or all of the length of catheter 20, or alternatively may be a
relatively short tubular member disposed at or near the distal end
of catheter 20. Various implantable carriers 21 may be either fixed
or slidable relative to expandable member 24, expandable member
shaft 27 and/or sheath 25. Slidable embodiments typically include
proximal carrier shaft 61, disposed proximal to carrier 21, to
advance carrier 21 along expandable member shaft 27 and/or
expandable member 24. Stents 30, with stent segments 32, are
typically fixedly mounted on implantable carrier 21, but slidable
mounting is also contemplated within the invention. Therefore, FIG.
1 depicts only one exemplary embodiment of a stent delivery device
and in no way should be interpreted to limit the scope of the
invention.
[0037] Stent segments 32 are described more fully in U.S. patent
application Ser. No. 10/637,713, previously incorporated by
reference, and Application Ser. No. 60/440,839, filed Jan. 17, 2003
(Attorney Docket No. 21629-000500), which is incorporated herein by
reference. 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 implantable carrier 21. Stent segments 32
preferably are in direct contact with each other, but may be
mounted with suitable spacing between segments to facilitate
deployment of each segment without interference with adjacent
segments. Alternatively, separate spacing elements may be disposed
between adjacent stent segments 32. Such spacing elements may be
plastically deformable or self-expanding so as to be deployable
with stent segments 32 into the vessel.
[0038] Stent segments 32 are preferably a malleable metal so as to
be plastically deformable by expandable member 24 as they are
expanded to the desired diameter in the vessel. Alternatively,
stent segments 32 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 sheath 25. Stent segments
32 may also be composed of polymers or other suitable biocompatible
materials. In self-expanding embodiments, expandable member 24 may
also be used for pre-dilatation of a lesion prior to stent
deployment or for augmenting the expansion of the self-expanding
stent segments. In some embodiments, stent segments 32 are coated
with a drug that inhibits restenosis, such as Rapamycin,
Paclitaxel, analogs, prodrugs, or derivatives of Rapamycin or
Paclitaxel, or other suitable agent(s), preferably carried in a
bioerodable polymeric carrier. Alternatively, stent segments 32 may
be coated with other types of drugs and therapeutic materials such
as antibiotics, thrombolytics, anti-thrombotics,
anti-inflammatories, cytotoxic agents, anti-proliferative agents,
vasodilators, gene therapy agents, radioactive agents,
immunosuppressants, chemotherapeutics, stem cells or the like. Such
materials may be coated over all or a portion of the surface of
stent segments 32, or stent segments 32 may include apertures,
holes, channels, or other features in which such materials may be
deposited.
[0039] Stent segments 32 may have a variety of configurations,
including but not limited to those described in Application Ser.
No. 60/440,839, previously incorporated by reference. In some
embodiments, stent segments 32 are completely separate from one
another without any interconnections, while in alternative
embodiments a stent may include couplings between two or more
adjacent segments which permit flexion between the segments. As a
further alternative, one or more adjacent stent segments 32 may be
connected by separable or frangible couplings that are separated
prior to or upon deployment, as described in U.S. application Ser.
No. 10/306,813, filed Nov. 27, 2002 (Attorney Docket No.
21629-000320), which is incorporated herein by reference.
[0040] Referring now to FIG. 2A, a distal portion of one embodiment
of a stent delivery catheter 100 is shown in side view. Stent
delivery catheter 100 may suitably include an expandable member
shaft 127, a carrier shaft 161 disposed over expandable member
shaft 127, a sheath 125 disposed over carrier shaft 161, and a
nosecone 128 distally mounted to expandable member shaft 127.
Expandable member shaft 127, carrier shaft 161, sheath 125 and
nosecone 128 may allow for passage of a guidewire 136. Stent
segments 132 may be disposed along an implantable carrier 121
coupled with carrier shaft 127, such that each stent segment 132 is
positioned on a portion of carrier 121 that is dividable from
adjacent carrier portions via perforations 160. In alternative
embodiments, two or more stent segments may be disposed over one
dividable carrier portion. Also, as described further below, any
suitable means for dividing adjacent carrier portions may be used,
with perforations 160 being merely one example. In the pictured
embodiment, implantable carrier 121 and stent segments 132 are
disposed over an expandable member (not shown) and within sheath
125. Sheath 125 may thus be retracted, as shown, to expose
implantable carrier 121, stent segments 132 and the expandable
member.
[0041] FIG. 2B shows the distal end of stent delivery device 100 in
cross-section so that expandable member 124 can be seen within
carrier 121, stent segments 132 and sheath 125. Also visible in
FIG. 2B is a valve 162 on the distal end of sheath 125. As is
described in further detail below, valve 162 may allow for
regulation of spacing between of stent segments 132 being exposed
from inside sheath 125 and those within sheath 125. Valve 162 may
also act as a cutting mechanism for separating adjacent segments of
carrier 121.
[0042] Although the embodiment in FIGS. 2A and 2B is shown with
sheath 125 disposed over carrier 121 and carrier shaft 161, in
alternative embodiments a carrier and carrier shaft may be disposed
over a sheath. In such embodiments, the sheath serves to contain
the expandable member, and when the sheath is retracted, the
expandable member expands to deploy the implantable carrier and the
stent segment(s). Therefore, although the figures and the following
description generally focuses on embodiments in which the sheath
covers the carrier and stent segments, the invention is not limited
to such embodiments.
[0043] That being said, implantable carrier 121 may be composed of
any suitable material or combination of materials and may have any
suitable length, inner diameter, thickness and other
characteristics. Generally, at least part of implantable carrier
121 will be expandable so that expandable member 124 can expand one
or more portions of implantable carrier 121 to deploy those
portions and their corresponding stent segment(s) 132. Implantable
carrier 121 may thus be expandable along its entire length or only
along a portion of its length near the distal end. Implantable
carrier 121 will also be dividable into carrier portions (or
"segments"), such that each portion corresponds to one or more
overlying stent segments 132. Carrier portions are coupled with
adjacent carrier portions by perforations 160 or connective
mechanisms for allowing the segments to be divided from one
another. Other connective mechanisms may include, for example,
frangible or breakable connections, thinned sections of carrier
material and/or the like. Typically, deployable portions of
implantable carrier 121 are composed of one or more biocompatible
materials, such as a biocompatible polymer, metal, woven polyester,
PTFE or anatomical tissue (human or animal). Carrier shaft 161 may
be made of any suitable flexible material, such as polyimide, PTFE,
FEP, Pebax or any other suitable polymer. To enhance axial sliding
over expandable member 124, implantable carrier 121 may be made of
a friction-reducing or friction-minimizing material and/or may be
covered with a friction reducing coating.
[0044] In some embodiments, implantable carrier 121 may be fixedly
coupled with delivery catheter 100 so that it does not slide
axially relative to expandable member shaft 127, expandable member
124 or the like. In other embodiments, implantable carrier 121 may
be slidably coupled with catheter 100 to allow it to move axially
relative to one or more catheter components. As mentioned above,
implantable carrier 121 and its segments may have any suitable
length, configuration and the like. In some embodiments, for
example, carrier 121 may be a tubular member disposed near the end
of stent delivery device 100, having a length coinciding with the
length of stent 130. In another embodiment, carrier 121 may extend
the entire (or nearly the entire) length of stent delivery device
100, with a distal portion of carrier 121 being expandable and
deployable. In some embodiments, carrier shaft 161 may be a piece
coupled with carrier 121, while in other embodiments shaft 161 and
carrier 121 may be integral. Still other embodiments may not
include a carrier shaft. Thus, many various embodiments are
contemplated within the scope of the invention.
[0045] In use, sheath 125 is withdrawn proximally to allow a
portion of expandable member 124 to expand. Expandable member 124
(shown in unexpanded configuration) then expands to contact, expand
and deploy one or more portions of implantable carrier 121 and one
or more corresponding stent segments 132. In this way, a selectable
length of implantable carrier 121 and stent segments 132 may be
expanded and deployed one at a time or in groups. As sheath 125 is
withdrawn proximally, more expandable member 124 is exposed, and
additional portions of implantable carrier 121 and stent segments
132 are expanded and deployed. In some embodiments, the expansion
of expandable member 124 against implantable carrier 121 will
generate enough force to separate an expanded, distal carrier
portion from an unexpanded, proximal carrier portion at
perforations 160 or alternative breakable connections between the
portions. In these or other embodiments, it may be advantageous to
also have a carrier-cutting valve 162 disposed on sheath 125 to
assist or enable separation of carrier segments. Valve 162 may also
enhance the ability of a user to control the number and spacing of
stent segments 132 that are deployed from delivery device 100.
Cutting valve 162 may have any suitable configuration, such as a
ring of sharpened, inwardly facing material at or near the distal
end of sheath 125, as pictured in FIG. 2B. In another embodiment,
portions of carrier 121 may be separated using a heated wire
disposed around the distal end of sheath 125 or on cutting valve
162. In any case, cutting valve 162 and/or other carrier cutting
members will be configured to separate adjacent carrier portions
without cutting or damaging expandable member 124, but some
embodiments may further include one or more protective members for
protecting expandable member 124 from damage by cutting valve
162.
[0046] Stent segments 132 may be coupled with corresponding
segments of carrier 121 in any suitable way, such as by adhesive,
sutures, staples, clips, fixation features on stent segments 132,
crimping stent segments 132 on carrier 121, partial or total
encapsulation of stent segments 132 in carrier material, and/or the
like. In fact, although stent segments 132 are shown disposed over
carrier 121, in other embodiments segments 132 may be disposed
beneath or within carrier 121. For example, carrier 121 may be
covering the outer surface of segments 132 and may contain an
anti-restenosis agent which elutes from carrier 121 into the vessel
wall.
[0047] In some embodiments, stent segments 132 may be coupled to
one or more implantable membranes (not shown) instead of or in
addition to carrier 121. In one embodiment, a membrane may comprise
one continuous, tubular membrane that extends between all stent
segments 132 of stent 130. Alternatively, a membrane may extend
between multiple stent segments 132 along only a portion of stent
130. Such a membrane may act as a graft, for example. In still
other embodiments, multiple unconnected membranes may be used, with
each membrane covering one or more stent segments 132. Furthermore,
membrane(s) may be coupled with stent segments 132 in any suitable
configuration. For example, membranes may be disposed on an outer
surface of stent segments 132, an inner surface, within openings in
segments 132, or the like. Membranes may be adhered to the segments
132 via any suitable process, such as coating, dipping, adhesive
fixation or the like. The membranes may be permeable, made of a
material such as Dacron, PTFE or the like, or impermeable, made of
urethane, other elastomers or the like. Some membranes may be
biodegradable, bioresorbable or bioerodable, while others remain
intact over time. The membranes may also be coated, impregnated or
otherwise coupled with one or more pharmaceutical agents such as a
drug that inhibits restenosis, such as Rapamycin, Paclitaxel,
analogs, prodrugs, or derivatives of Rapamycin or Paclitaxel, or
other suitable agent, preferably carried in or coated with a
bioerodable polymeric carrier. Alternatively, membranes may be
coated with other types of drugs and therapeutic materials such as
antibiotics, thrombolytics, anti-thrombotics, anti-inflammatories,
cytotoxic agents, anti-proliferative agents, vasodilators, gene
therapy agents, radioactive agents, immunosuppressants,
chemotherapeutics or stem cells. Such materials may be coated over
all or a portion of the surface of a membrane, or the membrane may
include apertures, holes, channels, or other features in which such
materials may be deposited.
[0048] Implantable carriers of the present invention may take any
of a number of different forms and are not limited to any specific
embodiments described herein. Examples of such embodiments are
shown in FIGS. 3A-3C, however it should be emphasized that these
are examples only and should not be interpreted to limit the scope
of the invention. That being said, FIG. 3A demonstrates one
embodiment of an implantable carrier 210 comprising a coil. The
coiled carrier 210 includes multiple carrier segments 211
corresponding with overlying stent segments 212. In one embodiment,
horizontal struts 214 may be used to strengthen each carrier
segment 211, while areas between adjacent segments do not include
struts, to allow for division of the segments 211 from each other.
Such an embodiment may also include perforations or other
frangible, breakable or bioerodable connections between carrier
segments 211, to facilitate division between segments 211. In
various embodiments, as already discussed, carrier segments 211 may
each contain one stent segment 212 or multiple stent segments
212.
[0049] In another embodiment, as in FIG. 3B, an implantable carrier
220 may be made of a mesh, scaffold or lattice configured material.
In one embodiment, carrier segments 221 may have a tighter-weaved,
thicker or otherwise stronger mesh than breakable areas 224 of
carrier 220 between segments 221, to allow for division of adjacent
carrier segments 221, to deploy the segments 221 and the
corresponding stent segments 222. Again, frangible, breakable or
bioerodable connections may also, or alternatively, be included
between carrier segments 221. Referring to FIG. 3C, another
embodiment of an implantable carrier 230 includes multiple axial
beams 233, each beam 233 including break points 234 located between
carrier segments 231 and their corresponding stent segments 232.
These exemplary embodiments demonstrate that implantable carriers,
carrier segments and breakable mechanisms may have any number of
various configurations.
[0050] In any of the above embodiments or in other embodiments, an
implantable carrier may be made of one or more biodegradable,
bioresorbable or bioerodable materials, such that the carrier will
eventually dissolve or degrade to leave only the unconnected stent
segments in the vessel or other body lumen. Such embodiments thus
enhance delivery of the stent segments, by providing a flexible
carrier for supporting the segments, while leaving no permanent
additional material in the vessel other than the stent segments. In
other embodiments, of course, the implantable carrier may be may of
non-degradable material(s), so as to remain in the vessel over a
longer period. Such may be advantageous, for example, if the
carrier-stent structure is to function as a vascular graft. In
various embodiments, carriers may also elute one or more
therapeutic agents and/or may dissolve or degrade to distribute
such agent(s).
[0051] Referring now to FIGS. 4A-4C, a method for delivering stent
segments is shown. (For purposes of clarity no vasculature or other
lumen is shown.) Generally, a stent delivery catheter 100 will be
advanced through a patient's vasculature or other lumen to a
desired location for delivering stent segments 132 and
corresponding segments of implantable carrier 121. At that point,
sheath 125 may be withdrawn or retracted proximally, as shown by
the two proximally directed arrows in FIG. 4A, to expose at least
part of expandable member 124 within carrier 121. Exposed
expandable member 124 may then be expanded, or may self-expand, as
shown in FIG. 4B. Upon such expansion, expandable member 124
contacts and expands an expandable portion of implantable carrier
121, which in turn causes one or more stent segments 132 to expand.
Expansion of expandable member 124 also causes division of
implantable carrier 121 via perforations 160 or other breakable
mechanism, such that a proximal portion of carrier 121 remains
within sheath 125 and a distal portion of carrier 121a is deployed
with corresponding deployed stent segments 132a, as shown in FIG.
4C. A cutting member 162 may also assist in dividing the proximal
portion of carrier 121 from the distal portion 121a. When
expandable member 124 is subsequently deflated, deployed
implantable carrier 121a and deployed stent segments 132a remain
expanded and in place. As mentioned above, deployed implantable
carrier 121a may then elute one or more therapeutic agents,
biodegrade with in the vessel, and/or the like. A physician may
then reposition catheter 100 to another site, retract sheath 125
further proximally and expand expandable member 124 to deploy
additional implantable carrier segments and corresponding stent
segments 132 of appropriate length. When a procedure is finished, a
physician may advance sheath 125 distally to cover expandable
member 124. Many variations on the method just described may be
used without departing from the scope of the present invention, for
example by adding, subtracting or substituting method steps.
[0052] 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.
* * * * *