U.S. patent application number 14/157350 was filed with the patent office on 2014-05-15 for asymmetric stent apparatus and method.
This patent application is currently assigned to TRIVASCULAR, INC.. The applicant listed for this patent is TRIVASCULAR, INC.. Invention is credited to Michael V. CHOBOTOV.
Application Number | 20140135899 14/157350 |
Document ID | / |
Family ID | 40472556 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140135899 |
Kind Code |
A1 |
CHOBOTOV; Michael V. |
May 15, 2014 |
ASYMMETRIC STENT APPARATUS AND METHOD
Abstract
A stent-graft system comprising a graft member and a stent
having a connection end interconnected with the graft member and a
free end opposed thereto. The stent includes a plurality of struts
extending between the connection end and the free end and at least
two of the struts having different lengths such that the free end
has a nonuniform profile. A method of securing at least one end of
a stent-graft within a vessel is also provided.
Inventors: |
CHOBOTOV; Michael V.; (Santa
Rosa, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TRIVASCULAR, INC. |
Santa Rosa |
CA |
US |
|
|
Assignee: |
TRIVASCULAR, INC.
Santa Rosa
CA
|
Family ID: |
40472556 |
Appl. No.: |
14/157350 |
Filed: |
January 16, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11861828 |
Sep 26, 2007 |
8663309 |
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14157350 |
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Current U.S.
Class: |
623/1.13 |
Current CPC
Class: |
A61F 2002/91558
20130101; A61F 2/91 20130101; A61F 2/89 20130101; A61F 2002/075
20130101; A61F 2002/8483 20130101; A61F 2/915 20130101; A61F 2/07
20130101; A61F 2220/0016 20130101; A61F 2/95 20130101; A61F
2230/0054 20130101; A61F 2230/0013 20130101; A61F 2/848 20130101;
A61F 2002/9511 20130101; A61F 2/82 20130101 |
Class at
Publication: |
623/1.13 |
International
Class: |
A61F 2/82 20060101
A61F002/82 |
Claims
1. A stent-graft system comprising: a tubular graft member
comprising at least one longitudinal lumen configured to confine a
flow of fluid therethrough; and a cylindrical stent including: a
connection end interconnected with the tubular graft member, a free
end axially opposed to the connection end, a plurality of struts
extending between the connection end and the free end, a first pair
of adjacent short struts diametrically opposed to a second pair of
adjacent short struts, the short struts defining a distal most
portion of the free end, and a first pair of adjacent long struts
diametrically opposed to a second pair of adjacent long struts, the
long struts defining a proximal most portion of the free end with
the pairs of long struts being circumferentially offset
approximately ninety degrees relative to the pairs of short
struts.
2. The stent-graft system according to claim 1 wherein each of the
struts circumferentially disposed between the first pair and second
pair of adjacent long struts is shorter than the first pair and
second pair of adjacent long struts.
3. The stent-graft system according to claim 2 wherein the strut
lengths of the struts circumferentially disposed between the first
pair and second pair of long struts decrease towards the adjacent
first pair and second pair of short struts.
4. The stent-graft system according to claim 1 wherein the struts
define a sinusoidal profile at the free end of the stent.
5. The stent-graft system according to claim 1 wherein the
cylindrical stent further comprises one or more barbs which are
configured to extend from the stent struts.
6. The stent-graft system according to claim 1 further comprising a
secondary stent which is connected to the free end of the first
pair and second pair of adjacent of long struts.
7. The stent-graft system according to claim 6 wherein the
secondary stent has a uniform profile at a free end thereof.
8. The stent-graft system according to claim 1 wherein a marker is
provided on at least one of the struts to identify an orientation
of the stent within a vessel.
9. The stent-graft system according to claim 1 further comprising
at least one belt which is releasably secured about the stent
between the connection end and the free end and which is releasable
therefrom.
10. The stent-graft system according to claim 1 wherein the stent
connection end further comprises a plurality of connection elements
configured for attachment to corresponding connection members on
the tubular graft member.
Description
RELATED PATENT APPLICATION
[0001] This patent application is a continuation and claims the
benefit of U.S. patent application Ser. No. 11/861,828, filed Sep.
26, 2007, naming Michael V. Chobotov as inventor, entitled
ASYMMETRIC STENT APPARATUS AND METHOD, and having attorney docket
no. TRI-0656-UT, which is incorporated by reference herein in its
entirety, including all text and drawings.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a system for the treatment
of disorders of the vasculature. More specifically, the invention
relates to a system for the treatment of disease or injury that
potentially compromises the integrity of a flow conduit in the
body. For example, an embodiment of the invention is useful in
treating indications in the digestive and reproductive systems as
well as indications in the cardiovascular system, including
thoracic and abdominal aortic aneurysms, arterial dissections (such
as those caused by traumatic injury), etc. that include a curved
lumen.
[0003] Medical devices for placement in a human or other animal
body are well known in the art. One class of medical devices
comprises endoluminal devices such as stents, stent-grafts,
filters, coils, occlusion baskets, valves, and the like. A stent
typically is an elongated device used to support an intraluminal
wall. In the case of a stenosis, for example, a stent provides an
unobstructed conduit through a body lumen in the area of the
stenosis. Such a stent may also have a prosthetic graft layer of
fabric or covering lining the inside and/or outside thereof. A
covered stent is commonly referred to in the art as an intraluminal
prosthesis, an endoluminal or endovascular graft (EVG), a
stent-graft, or endograft.
[0004] An endograft may be used, for example, to treat a vascular
aneurysm by removing or reducing the pressure on a weakened part of
an artery so as to reduce the risk of rupture. Typically, an
endograft is implanted in a blood vessel at the site of a stenosis
or aneurysm endoluminally, i.e. by so-called "minimally invasive
techniques" in which the endograft, typically restrained in a
radially compressed configuration by a sheath, crocheted or knit
web, catheter or other means, is delivered by an endograft delivery
system or "introducer" to the site where it is required. The
introducer may enter the vessel or lumen from an access location
outside the body, such as purcutaneously through the patient's
skin, or by a "cut down" technique in which the entry vessel or
lumen is exposed by minor surgical means. The term "proximal" as
used herein refers to portions of the endograft, stent or delivery
system relatively closer to the end outside of the body, whereas
the term "distal" is used to refer to portions relatively closer to
the end inside the body.
[0005] After the introducer is advanced into the body lumen to the
endograft deployment location, the introducer is manipulated to
cause the endograft to be deployed from its constrained
configuration, whereupon the stent is expanded to a predetermined
diameter at the deployment location, and the introducer is
withdrawn. Stent expansion typically is effected by spring
elasticity, balloon expansion, and/or by the self-expansion of a
thermally or stress-induced return of a memory material to a
pre-conditioned expanded configuration.
[0006] Among the many applications for endografts is that of
deployment in lumen for repair of an aneurysm, such as a thorasic
aortic aneurysm (TAA) or an abdominal aortic aneurysm (AAA). An AAA
is an area of increased aortic diameter that generally extends from
just below the renal arteries to the aortic bifurcation and a TAA
most often occurs in the descending thoracic aorta. AAA and TAA
generally result from deterioration of the arterial wall, causing a
decrease in the structural and elastic properties of the artery. In
addition to a loss of elasticity, this deterioration also causes a
slow and continuous dilation of the lumen.
[0007] The standard surgical repair of AAA or TAA is an extensive
and invasive procedure typically requiring a week long hospital
stay and an extended recovery period. To avoid the complications of
the surgical procedure, practitioners commonly resort to a
minimally invasive procedure using an endoluminal endograft to
reinforce the weakened vessel wall, as mentioned above. At the site
of the aneurysm, the practitioner deploys the endograft, anchoring
it above and below the aneurysm to relatively healthy tissue. The
anchored endograft diverts blood flow away from the weakened
arterial wall, minimizing the exposure of the aneurysm to high
pressure.
[0008] Intraluminal stents for repairing a damaged or diseased
artery or to be used in conjunction with a graft for delivery to an
area of a body lumen that has been weakened by disease or damaged,
such as an aneurysm of the thorasic or abdominal aorta, are well
established in the art of medical science.
[0009] While intraluminal stents are advantageous in anchoring the
device, an improved system for aligning stents in curved vessels or
lumens is desired.
SUMMARY OF THE INVENTION
[0010] In one aspect, the invention provides a stent-graft system
comprising a graft member and a stent having a connection end
interconnected with the graft member and a free end opposed
thereto. The stent includes a plurality of struts extending between
the connection end and the free end and at least two of the struts
having different lengths such that the free end has a nonuniform
profile.
[0011] In another aspect, the invention provides a method of
securing at least one end of a graft within a vessel. The method
comprises: positioning within the vessel a stent-graft comprising a
stent and a graft with a connection end of the stent connected to
an end of the graft, the stent having a free end opposite the
connection end, the stent including a plurality of nonuniform
struts such that the free end has at least one short strut and at
least one long strut; positioning the stent-graft within the vessel
such that the at least one short strut is aligned with an inner
radial curvature of the vessel; and deploying the stent.
[0012] Other aspects and advantages of the present invention will
be apparent from the detailed description of the invention provided
hereinafter.
[0013] The invention is best understood from the following detailed
description when read in connection with the accompanying drawings.
It is emphasized that, according to common practice, the various
features of the drawings are not to scale. On the contrary, the
dimensions of the various features are arbitrarily expanded or
reduced for clarity. Included in the drawings are the following
figures:
[0014] FIG. 1 shows a prior art endovascular graft portion fully
deployed within an angulated internal vasculature of the
patient.
[0015] FIG. 2 shows an endovascular graft portion in accordance
with an embodiment of the present invention fully deployed within
an angulated internal vasculature of the patient.
[0016] FIG. 3 shows a flat pattern of an embodiment of a stent in
accordance with an embodiment of the present invention.
[0017] FIG. 4 shows a flat pattern of another alternative
embodiment of a stent in accordance with the present invention.
[0018] FIG. 5 shows a portion of an endovascular graft according to
an embodiment of the present invention partially deployed within an
angulated internal vasculature of the patient.
[0019] FIG. 6 shows the endovascular graft portion of FIG. 5 fully
deployed within the internal vasculature of the patient.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Although the invention is illustrated and described herein
with reference to specific embodiments, the invention is not
intended to be limited to the details shown. Rather, various
modifications may be made in the details within the scope and range
of equivalents of the claims and without departing from the
invention.
[0021] Unless otherwise stated, the term "graft" or "endovascular
graft" is used herein to refer to a prosthesis capable of repairing
and/or replacing diseased vessels or portions thereof, including
generally tubular and bifurcated devices and any components
attached or integral thereto. For purposes of illustration, the
graft embodiments described herein may be used in the endovascular
treatment of abdominal aortic aneurysms (AAA) or thoracic aortic
aneurysms, however, other applications are within the scope of the
present invention. For the purposes of this application, with
reference to endovascular graft devices, the term "proximal"
describes the end of the graft that will be oriented towards the
oncoming flow of bodily fluid, typically blood, when the device is
deployed within a body passageway. The term "distal" therefore
describes the graft end opposite the proximal end. Finally, while
the drawings in the various figures are accurate representations of
the various embodiments of the present invention, the proportions
of the various components thereof are not necessarily shown to
exact scale within and among or between any given figure(s).
[0022] Referring to FIG. 1, a prior art stent graft 110 is
illustrated deployed within an angulated vessel 1 of a patient. The
stent graft 110 includes a stent 140 connected to a graft 113 as is
known in the art. The stent 140 includes a plurality of struts 141
which each have a uniform length to define a uniform free end 142
with all of the struts 141 terminating in a common plane P. With
such a stent 140 positioned in an angulated vessel 1, the stent 140
may not align properly. For example, an inner strut 141a may
liftoft from an inner radial curvature 3 of the vessel 1 as
indicated at arrow A. Alternatively, an outer strut 141b may
penetrate the vessel wall at an outer radial curvature 5 of the
vessel 1.
[0023] Referring to FIGS. 2 and 3, a stent graft 10 in accordance
with a first embodiment of the invention will be described. An end
of the graft 10 is illustrated and may represent the proximal or
distal end of the graft 10. The graft 10 includes a generally
tubular structure or graft body section 13 comprised of one or more
layers of fusible material, such as expanded
polytetrafluoroethylene (ePTFE). An inflatable cuff 16 is disposed
at or near the end 14 of graft body section 13. A neck portion 23
is disposed in the vicinity of graft body section end 14 and serves
as an additional means to help seal the deployed graft against the
inside of a body passageway. Graft body section 13 forms a
longitudinal lumen 22 configured to confine a flow of fluid
therethrough.
[0024] An attachment ring 24 is affixed to or integrally formed in
graft body section 13, or as shown in FIG. 2, at or near graft body
section end 14 and neck portion 23. In the embodiment of FIG. 1,
attachment ring 24 is a serpentine ring structure comprising apices
28. Other embodiments of attachment ring 24 may take different
configurations. Attachment ring 24 may be made from any suitable
material that permits expansion from a constrained state, most
usefully a shape memory alloy having superelastic properties such
as nickel titanium (NiTi). Other suitable attachment ring 24
materials include stainless steel, nickel-cobalt alloys such as
MP35N, tantalum and its alloys, polymeric materials, composites,
and the like. Attachment ring 24 (as well as all stents and
attachment rings described herein) may be configured to self-expand
from the illustrated radially constrained state.
[0025] Some apices 28 may also comprise a attachment ring connector
element (not shown). The number of connector elements may vary and
can be distributed, for example, on every apex, every third or
fourth apex, or any other pattern are within the scope of the
present invention.
[0026] Graft 10 further comprises one or more stents 40 having, in
the deployed state, a generally free end 42 and a connection end
44. FIG. 2 illustrates a proximal stent 40, but the stents 40 may
additionally or alternatively be provided on the distal end of the
graft 10. In the case of a bifurcated graft, a stent 40 may be
provided on the distal end of each leg of the bifurcated graft.
[0027] As shown in FIG. 2, stent 40 is typically, though not
necessarily, made a part of graft 10 by having the connection end
44 affixed or connected to attachment ring 24 via connector
elements as described in detail below. The connection end 44 of
stent 40 may also be affixed or embedded directly to or in neck
portion 23 and/or other portions of graft body section 13. In
addition, the attachment ring and the stent may not be mechanically
or otherwise fastened to one another but rather unified, formed of
a monolithic piece of material, such as NiTi.
[0028] This configuration of stent 40, attachment ring 24, neck
portion 23, and cuff 16 helps to separate the sealing function of
cuff 16, which requires conformation and apposition to the vessel
wall within which graft 10 is deployed without excessive radial
force, from the anchoring function of stent 40 (attachment ring 24
and neck portion 23 play intermediate roles).
[0029] Referring to FIGS. 2 and 3, each stent 40 of the present
invention generally comprises a series of interconnected struts 41
which will be described in more detail hereinafter. Each stent 40
further comprises stent connector elements 48 at the connection end
44 thereof. The stent connector elements 48 are configured to be
affixed or otherwise connected to attachment ring connector
elements 30 via coupling members (not shown), for example, threads
or wires. The stents 40 may be manufactured from any suitable
material, including the materials suitable for attachment ring 24.
When manufactured from a shape memory alloy having superelastic
properties such as NiTi, the stents 40 may be configured to
self-expand upon release from the contracted state. The strut
structure is often formed as a flat structure, as illustrated in
FIGS. 3-4, and thereafter, wrapped and connected in a cylindrical
or other configuration, as illustrated in FIG. 2.
[0030] Each stent 40 may include one or more barbs 43. A barb 43
can be any outwardly directed protuberance, typically terminating
in a sharp point that is capable of at least partially penetrating
a body passageway in which graft 10 is deployed (typically the
initial and medial layers of a blood vessel such as the abdominal
aorta). The number of barbs, the length of each barb, each barb
angle, and the barb orientation may vary from barb to barb within a
single stent 40 or between multiple stents 40 within a single
graft. Although the various barbs 43 may be attached to or fixed on
the stent struts 41, it is preferred that they be integrally formed
as part of the stent struts 41, as shown in the various
figures.
[0031] As illustrated, the struts 41 can have various
configurations and lengths. In the present invention, the struts 41
have differing lengths such that the stent 40 has a nonuniform free
end 42. That is, the ends of all different struts 41 do not lie
along a single plane. In the present embodiment, the short struts
41a define the distal most portions of the free end 42 while the
long struts 41 c define the proximal most portions of the free end
42 and the intermediate struts 41b define portions therebetween. In
the present embodiment, the free end 42 has a sinusoidal
configuration as illustrated in FIG. 3. For some embodiments, the
strut lengths slope to a pair of short struts offset approximately
ninety degrees relative to the long struts. For some embodiments,
the short struts are configured to be aligned with an inner radial
curvature and outer radial curvature of an angulated vessel.
[0032] Referring to FIG. 2, in a preferred deployment, the stent 40
is preferably aligned within an angulated vessel such that a pair
of the short struts 41a are positioned against an inner radial
curvature 3 of the vessel 1 and a second pair of the short struts
41a are positioned against an outer radial curvature 5 of the
vessel 1. To facilitate alignment, one or more of the struts 41 may
be provided with a radiopaque marker 50 or the like. In this
orientation, the long struts 41c are along the sides of the vessel
1 and do not cause liftoff or penetration.
[0033] Referring to FIGS. 4-6, a second embodiment of the invention
is illustrated. The stent graft 10' is similar to in the previous
embodiment, but the stent 70 includes a portion which is generally
the same as the stent 40 of the previous embodiment and a secondary
stent portion 80 connected thereto. The secondary stent portion 80
has a plurality of struts 81 which have a uniform length such that
the secondary stent 80 has a generally uniform free end 82, i.e.
each of the struts 81 terminating in generally the same plane P.
The connection end 84 is desirably connected to the long struts 41c
of the stent portion 40.
[0034] In use, the stent 70 is preferably deployed in a multistage
manner. The stent 70 is positioned within the vessel 1 with the
secondary stent portion 80 aligned with a generally straight
portion 7 of the vessel 1 and deployed. The secondary stent portion
80 may connect to the straight portion 7 of the vessel 1, for
example, via barbs or the like, and anchor the stent graft 10' in
position. Since the vessel portion 7 is straight, the uniform
struts 81 are not subject to liftoff or penetration. At this time,
the nonuniform stent portion 40 remains in a constrained state via
belt 35 or the like.
[0035] The staged deployment of the stent 70 also facilitates
self-alignment of the stent portion 40 and graft 10. Upon
deployment of the secondary stent portion 80, the graft 13 is free
to expand and distal fluid flow flows into the graft 13 and creates
a "windsock" effect. That is, the distal fluid flow applies a
slight distal force upon the graft 13. This distal force helps to
align the graft 13 and the stent 40 within the vessel 1, which is
particularly advantageous during deployment of the stent graft
within the angulated vessel 1, for example, which is an aortic
arch.
[0036] The stent portion 40 may thereafter be deployed by release
of the belt 35 whereby the stent portion 40 deploys in a manner
similar to described above. As shown in FIG. 6, the stent 40 is
preferably aligned within the angulated vessel 1 such that a pair
of the short struts 41 a are positioned against the inner radial
curvature 3 of the vessel 1 and a second pair of the short struts
41 a are positioned against the outer radial curvature 5 of the
vessel 1. Again, to facilitate orientation, one or more of the
struts 41 may be provided with a radiopaque marker 50 or the like.
Orientation is preferably performed prior to deployment of the
secondary stent portion 80. As in the previous embodiment, in this
orientation, the long struts 41c are along the sides of the vessel
1 and do not cause liftoff or penetration.
[0037] While preferred embodiments of the invention have been shown
and described herein, it will be understood that such embodiments
are provided by way of example only. Numerous variations, changes
and substitutions will occur to those skilled in the art without
departing from the spirit of the invention. Accordingly, it is
intended that the appended claims cover all such variations as fall
within the spirit and scope of the invention.
* * * * *