U.S. patent application number 11/699700 was filed with the patent office on 2007-08-30 for non-circular stent.
This patent application is currently assigned to Bolton Medical, Inc.. Invention is credited to Samuel Arbefeuille, Humberto Berra.
Application Number | 20070203566 11/699700 |
Document ID | / |
Family ID | 34222399 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070203566 |
Kind Code |
A1 |
Arbefeuille; Samuel ; et
al. |
August 30, 2007 |
Non-circular stent
Abstract
A vascular repair device includes a tubular graft body having a
central longitudinal axis and a structural framework having at
least one stent connected to the graft body in a partially
compressed state, the stent having substantially linear struts and
apices between adjacent pairs of the struts, each of the apices
being in the same plane as the adjacent pairs of the struts. Also
provided is a vascular repair device where the stent defines a
cross plane orthogonal to the longitudinal axis and has a cross
profile having a polygonal shape parallel to the cross-sectional
plane and viewed along said longitudinal axis.
Inventors: |
Arbefeuille; Samuel;
(Hollywood, FL) ; Berra; Humberto; (Cooper City,
FL) |
Correspondence
Address: |
MAYBACK & HOFFMAN, P.A.
5722 S. FLAMINGO ROAD #232
FORT LAUDERDALE
FL
33330
US
|
Assignee: |
Bolton Medical, Inc.
Sunrise
FL
|
Family ID: |
34222399 |
Appl. No.: |
11/699700 |
Filed: |
January 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10784462 |
Feb 23, 2004 |
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11699700 |
Jan 30, 2007 |
|
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60499652 |
Sep 3, 2003 |
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60500155 |
Sep 4, 2003 |
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Current U.S.
Class: |
623/1.13 ;
623/1.15 |
Current CPC
Class: |
A61F 2002/828 20130101;
A61F 2/9517 20200501; A61F 2250/0098 20130101; A61F 2002/9528
20130101; A61F 2002/075 20130101; Y10T 74/18392 20150115; Y10T
29/49799 20150115; A61F 2002/9511 20130101; A61F 2/962 20130101;
A61M 25/0108 20130101; A61F 2/07 20130101; A61F 2002/9505 20130101;
A61F 2/89 20130101; A61F 2/966 20130101; A61F 2210/0014 20130101;
A61F 2002/9665 20130101; A61F 2/95 20130101; A61F 2230/0091
20130101; A61M 25/0105 20130101 |
Class at
Publication: |
623/001.13 ;
623/001.15 |
International
Class: |
A61F 2/86 20060101
A61F002/86 |
Claims
1. A vascular repair device, comprising: a tubular graft body
having a central longitudinal axis; and a structural framework
having at least one stent connected to said graft body in a
partially compressed state, said stent having: substantially linear
struts; and apices between adjacent pairs of said struts, each of
said apices being in the same plane as said adjacent pairs of said
struts.
2. The vascular repair device according to claim 1, wherein said at
least one stent is a Z-stent.
3. The vascular repair device according to claim 1, wherein said
stent has between 10 and 20 of said apices.
4. The vascular repair device according to claim 1, wherein: said
stent defines a cross profile orthogonal to said longitudinal axis;
and said cross profile has a polygonal shape selected from one of
the group consisting of a decagon, an undecagon, a dodecagon, a
tridecagon, a tetradecagon, a pentadecagon, a hexadecagon, a
heptadecagon, a octadecagon, an enneadecagon, and an icosagon.
5. The vascular repair device according to claim 1, wherein said at
least one stent is a plurality of stents.
6. The vascular repair device according to claim 5, wherein said
plurality of stents are independently connected to said graft
body.
7. The vascular repair device according to claim 6, wherein said
plurality of stents are independently connected to said graft body
without touching one another.
8. The vascular repair device according to claim 5, wherein said
plurality of stents includes at least one bare stent.
9. The vascular repair device according to claim 1, wherein said at
least one stent is sewn to said graft body.
10. The vascular repair device according to claim 9, wherein said
graft body has exterior and interior surfaces and said at least one
stent is sewn to at least one of said exterior surface and said
interior surface.
11. The vascular repair device according to claim 5, wherein: said
stents define a proximal-most stent, a distal-most stent, and a
bare stent connected to said interior surface; and a remainder of
said stents is connected to said exterior surface.
12. The vascular repair device according to claim 1, wherein said
graft body has an internal diameter and said stent has an internal
at-rest diameter larger than said internal diameter.
13. The vascular repair device according to claim 1, wherein the
stent is a wire of a material having a shape memory.
14. The vascular repair device according to claim 13, wherein said
material is selected from at least one of a group consisting of
nitinol, stainless steel, biopolymers, cobalt chrome alloy, and
titanium alloy.
15. A vascular repair device, comprising: a tubular graft body
having a longitudinal axis; and a structural framework having at
least one stent connected to said graft body in a partially
compressed state, said stent having a polygonal profile orthogonal
to said longitudinal axis.
16. The vascular repair device according to claim 15, wherein: said
at least one stent is a Z-stent; and said polygonal profile is a
shape selected from one of the group consisting of a decagon, an
undecagon, a dodecagon, a tridecagon, a tetradecagon, a
pentadecagon, a hexadecagon, a heptadecagon, a octadecagon, an
enneadecagon, and an icosagon.
17. A vascular repair device, comprising: a tubular graft body
having a longitudinal axis; and a structural framework having at
least one Z-stent connected to said graft body in a partially
compressed state, said Z-stent having substantially linear struts;
and apices between adjacent pairs of said struts, each of said
apices being in the same plane as said adjacent pairs of said
struts.
18. In a vascular repair device having a tubular graft body with a
longitudinal axis, a structural framework comprising: at least one
stent connected to the graft body, said stent having a polygonal
profile orthogonal to the longitudinal axis.
19. A vascular repair device, comprising: a tubular graft body
having a central longitudinal axis; and a structural framework
having at least one stent connected to said graft body, said stent
defining: a cross plane orthogonal to said longitudinal axis; and a
cross profile parallel to said cross-sectional plane and viewed
along said longitudinal axis, said cross profile having a polygonal
shape.
20. A vascular repair device, comprising: a tubular graft body
having a longitudinal axis; and a structural framework having at
least one Z-stent connected to said graft body in a partially
compressed state, said Z-stent having a polygonal profile
orthogonal to said longitudinal axis, said polygonal profile being
a shape selected from one of the group consisting of a decagon, an
undecagon, a dodecagon, a tridecagon, a tetradecagon, a
pentadecagon, a hexadecagon, a heptadecagon, a octadecagon, an
enneadecagon, and an icosagon.
21. The device according to claim 1, wherein said apices are at
least one of curved and angular.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 10/784,462, filed Feb. 23, 2004, which
application claims the benefit under 35 U.S.C. .sctn. 119(e) of
U.S. Provisional Applications Nos. 60/499,652, filed Sep. 3, 2003,
and 60/500,155, filed Sep. 4, 2003, the complete disclosures of
which are each hereby incorporated by reference herein in their
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention lies in the field of endoluminal blood vessel
repairs. The invention specifically relates to a non-circular
stent, which can be used to endoluminally repair aneurysm and/or
dissections of the thoracic transverse aortic arch, thoracic
posterior aortic arch, and the descending thoracic portion of the
aorta.
[0004] 2. Description of the Related Art
[0005] A stent graft is an implantable device made of a tube-shaped
surgical graft covering and an expanding or self-expanding frame.
The stent graft is placed inside a blood vessel to bridge, for
example, an aneurismal, dissected, or other diseased segment of the
blood vessel, and, thereby, exclude the hemodynamic pressures of
blood flow from the diseased segment of the blood vessel.
[0006] In selected patients, a stent graft advantageously
eliminates the need to perform open thoracic or abdominal surgical
procedures to treat diseases of the aorta and eliminates the need
for total aortic reconstruction. Thus, the patient has less trauma
and experiences a decrease in hospitalization and recovery times.
The time needed to insert a stent graft is substantially less than
the typical anesthesia time required for open aortic bypass
surgical repair, for example.
[0007] Use of surgical and/or endovascular grafts have widespread
use throughout the world in vascular surgery. There are many
different kinds of vascular graft configurations. Some have
supporting framework over their entirety, some have only two stents
as a supporting framework, and others simply have the tube-shaped
graft material with no additional supporting framework, an example
that is not relevant to the present invention.
[0008] One of the most commonly known supporting stent graft
frameworks is that disclosed in U.S. Pat. Nos. 5,282,824 and
5,507,771 to Gianturco (hereinafter collectively referred to as
"Gianturco"). Gianturco describes a zig-zag-shaped, self-expanding
stent commonly referred to as a z-stent. The stents are,
preferably, made of nitinol, but also have been made from stainless
steel and other biocompatible materials.
[0009] There are various features characterizing a stent graft. The
first significant feature is the tube of graft material. This tube
is commonly referred to as the graft and forms the tubular shape
that will, ultimately, take the place the diseased portion of the
blood vessel. The graft is, preferably, made of a woven sheet
(tube) of polyester or PTFE. The circumference of the graft tube
is, typically, at least as large as the diameter and/or
circumference of the vessel into which the graft will be inserted
so that there is no possibility of blood flowing around the graft
(also referred to as endoleak) to either displace the graft or to
reapply hemodynamic pressure against the diseased portion of the
blood vessel. Accordingly, to so hold the graft, self-expanding
frameworks are attached typically to the graft material, whether on
the interior or exterior thereof. Because blood flow within the
lumen of the graft could be impaired if the framework was disposed
on the interior wall of the graft, the framework is connected
typically to the exterior wall of the graft. The ridges formed by
such an exterior framework help to provide a better fit in the
vessel by providing a sufficiently uneven outer surface that
naturally grips the vessel where it contacts the vessel wall and
also provides areas around which the vessel wall can endothelialize
to further secure the stent graft in place.
[0010] One of the significant dangers in endovascular graft
technology is the possibility of the graft migrating from the
desired position in which it is installed. Therefore, various
devices have been created to assist in anchoring the graft to the
vessel wall.
[0011] One type of prior art prosthetic device is a stent graft
made of a self-expanding metallic framework. For delivery, the
stent graft is, first, radially compressed and loaded into an
introducer system that will deliver the device to the target area.
When the introducer system holding the stent graft positioned in an
appropriate location in the vessel and allowed to open, the radial
force imparted by the self-expanding framework is helpful, but,
sometimes, not entirely sufficient, in endoluminally securing the
stent graft within the vessel.
[0012] U.S. Pat. No. 5,824,041 to Lenker et al. (hereinafter
"Lenker") discloses an example of a stent graft delivery system.
Lenker discloses various embodiments in which a sheath is
retractable proximally over a prosthesis to be released. With
regard to FIGS. 7 and 8, Lenker names components 72 and 76,
respectively, as "sheath" and "prosthesis-containment sheath."
However, the latter is merely the catheter in which the prosthesis
74 and the sheath 72 are held. With regard to FIGS. 9 and 10, the
sheath 82 has inner and outer layers 91, 92 fluid-tightly connected
to one another to form a ballooning structure around the prosthesis
P. This ballooning structure inflates when liquid is inflated with
a non-compressible fluid medium and flares radially outward when
inflated. With regard to FIGS. 13 to 15, Lenker discloses the
"sheath" 120, which is merely the delivery catheter, and an
eversible membrane 126 that "folds back over itself (everts) as the
sheath 120 is retracted so that there are always two layers of the
membrane between the distal end of the sheath [120] and the
prosthesis P." Lenker at col. 9, lines 63 to 66. The eversion
(peeling back) is caused by direct connection of the distal end 130
to the sheath 120. The Lenker delivery system shown in FIGS. 19A to
19D holds the prosthesis P at both ends 256, 258 while an outer
catheter 254 is retracted over the prosthesis P and the inner
sheath 260. The inner sheath 260 remains inside the outer catheter
254 before, during, and after retraction. Another structure for
holding the prosthesis P at both ends is illustrated in FIGS. 23A
and 23B. Therein, the proximal holder having resilient axial
members 342 is connected to a proximal ring structure 346. FIGS.
24A to 24C also show an embodiment for holding the prosthesis at
both ends inside thin-walled tube 362.
[0013] To augment radial forces of stents, some prior art devices
have added proximal and/or distal stents that are not entirely
covered by the graft material. By not covering with graft material
a portion of the proximal/distal ends of the stent, these stents
have the ability to expand further radially than those stents that
are entirely covered by the graft material. By expanding further,
the proximal/distal stent ends better secure to the interior wall
of the vessel and, in doing so, press the extreme cross-sectional
surface of the graft ends into the vessel wall to create a fixated
blood-tight seal.
[0014] One example of such a prior art exposed stent can be found
in United States Patent Publication US 2002/0198587 to Greenberg et
al. The modular stent graft assembly therein has a three-part stent
graft: a two-part graft having an aortic section 12 and an iliac
section 14 (with four sizes for each) and a contralateral iliac
occluder 80. FIGS. 1, 2, and 4 to 6 show the attachment stent 32.
As illustrated in FIGS. 1, 2, and 4, the attachment stent 32, while
rounded, is relatively sharp and, therefore, increases the
probability of puncturing the vessel.
[0015] A second example of a prior art exposed stent can be found
in U.S. Patent Publication 2003/0074049 to Hoganson et al.
(hereinafter "Hoganson"), which discloses a covered stent 10 in
which the elongated portions or sections 24 of the ends 20a and 20b
extend beyond the marginal edges of the cover 22. See Hoganson at
FIGS. 1, 3, 9, 11a, 11b, 12a, 12b, and 13. However, these extending
exposed edges are triangular, with sharp apices pointing both
upstream and downstream with regard to a graft placement location.
Such a configuration of the exposed stent 20a, 20b increases the
possibility of puncturing the vessel. In various embodiments shown
in FIGS. 6a, 6b, 6c, 10, 14a, Hoganson teaches completely covering
the extended stent and, therefore, the absence of a stent extending
from the cover 22. It is noted that the Hoganson stent is implanted
by inflation of a balloon catheter.
[0016] Another example of a prior art exposed stent can be found in
U.S. Pat. No. 6,565,596 to White et al. (hereinafter "White I"),
which uses a proximally extending stent to prevent twisting or
kinking and to maintain graft against longitudinal movement. The
extending stent is expanded by a balloon and has a sinusoidal
amplitude greater than the next adjacent one or two sinusoidal
wires. White I indicates that it is desirable to space wires
adjacent upstream end of graft as close together as is possible.
The stent wires of White I are actually woven into graft body by
piercing the graft body at various locations. See White I at FIGS.
6 and 7. Thus, the rips in the graft body can lead to the
possibility of the exposed stent moving with respect to the graft
and of the graft body ripping further. Between the portions of the
extending stent 17, the graft body has apertures.
[0017] The stent configuration of U.S. Pat. No. 5,716,393 to
Lindenberg et al. is similar to White I in that the outermost
portion of the one-piece stent--made from a sheet that is
cut/punched and then rolled into cylinder--has a front end with a
greater amplitude than the remaining body of the stent
[0018] A further example of a prior art exposed stent can be found
in U.S. Pat. No. 6,524,335 to Hartley et al. (hereinafter
"Hartley"). FIGS. 1 and 2 of Hartley particularly disclose a
proximal first stent 1 extending proximally from graft proximal end
4 with both the proximal and distal apices narrowing to pointed
ends.
[0019] Yet another example of a prior art exposed stent can be
found in U.S. Pat. No. 6,355,056 to Pinheiro (hereinafter "Pinheiro
I"). Like the Hartley exposed stent, Pinheiro discloses exposed
stents having triangular, sharp proximal apices.
[0020] Still a further example of a prior art exposed stent can be
found in U.S. Pat. No. 6,099,558 to White et al. (hereinafter
"White II"). The White II exposed stent is similar to the exposed
stent of White I and also uses a balloon to expand the stent.
[0021] An added example of a prior art exposed stent can be found
in U.S. Pat. No. 5,871,536 to Lazarus, which discloses two support
members 68 longitudinally extending from proximal end to a rounded
point. Such points, however, create a very significant possibility
of piercing the vessel.
[0022] An additional example of a prior art exposed stent can be
found in U.S. Pat. No. 5,851,228 to Pinheiro (hereinafter "Pinheiro
II"). The Pinheiro II exposed stents are similar to the exposed
stents of Pinheiro I and, as such, have triangular, sharp, proximal
apices.
[0023] Still another example of a prior art exposed stent can be
found in Lenker (U.S. Pat. No. 5,824,041), which shows a
squared-off end of the proximal and distal exposed band members 14.
A portion of the exposed members 14 that is attached to the graft
material 18, 20 is longitudinally larger than a portion of the
exposed members 14 that is exposed and extends away from the graft
material 18, 20. Lenker et al. does not describe the members 14 in
any detail.
[0024] Yet a further example of a prior art exposed stent can be
found in U.S. Pat. No. 5,824,036 to Lauterjung, which, of all of
the prior art embodiments described herein, shows the most pointed
of exposed stents. Specifically, the proximal ends of the exposed
stent are apices pointed like a minaret. The minaret points are so
shaped intentionally to allow forks 300 (see Lauterjung at FIG. 5)
external to the stent 154 to pull the stent 154 from the sheath
302, as opposed to being pushed.
[0025] A final example of a prior art exposed stent can be found in
U.S. Pat. No. 5,755,778 to Kleshinski. The Kleshinski exposed
stents each have two different shaped portions, a triangular base
portion and a looped end portion. The totality of each exposed
cycle resembles a castellation. Even though the end-most portion of
the stent is curved, because it is relatively narrow, it still
creates the possibility of piercing the vessel wall.
[0026] All of these prior art stents suffer from the
disadvantageous characteristic that the relatively sharp proximal
apices of the exposed stents have a shape that is likely to
puncture the vessel wall.
[0027] Devices other than exposed stents have been used to inhibit
graft migration. A second of such devices is the placement of a
relatively stiff longitudinal support member longitudinally
extending along the entirety of the graft.
[0028] The typical stent graft has a tubular body and a
circumferential framework. This framework is not usually
continuous. Rather, it typically takes the form of a series of
rings along the tubular graft. Some stent grafts have only one or
two of such rings at the proximal and/or distal ends and some have
many stents tandemly placed along the entirety of the graft
material. Thus, the overall stent graft has an "accordion" shape.
During the systolic phase of each cardiac cycle, the hemodynamic
pressure within the vessel is substantially parallel with the
longitudinal plane of the stent graft. Therefore, a device having
unsecured stents, could behave like an accordion or concertina with
each systolic pulsation, and may have a tendency to migrate
downstream. (A downstream migration, to achieve forward motion, has
a repetitive longitudinal compression and extension of its
cylindrical body.) Such movement is entirely undesirable.
Connecting the stents with support along the longitudinal extent of
the device thereof can prevent such movement. To provide such
support, a second anti-migration device can be embodied as a
relatively stiff longitudinal bar connected to the framework.
[0029] A clear example of a longitudinal support bar can be found
in Pinheiro I (U.S. Pat. No. 6,355,056) and Pinheiro II (U.S. Pat.
No. 5,851,228). Each of these references discloses a plurality of
longitudinally extending struts 40 extending between and directly
interconnecting the proximal and distal exposed stents 20a, 20b.
These struts 40 are designed to extend generally parallel with the
inner lumen 15 of the graft 10, in other words, they are
straight.
[0030] Another example of a longitudinal support bar can be found
in U.S. Pat. No. 6,464,719 to Jayaraman. The Jayaraman stent is
formed from a graft tube 21 and a supporting sheet 1 made of
nitinol. This sheet is best shown in FIG. 3. The end pieces 11, 13
of the sheet are directly connected to one another by wavy
longitudinal connecting pieces 15 formed by cutting the sheet 1. To
form the stent graft, the sheet 1 is coiled with or around the
cylindrical tube 21. See FIGS. 1 and 4. Alternatively, a plurality
of connecting pieces 53 with holes at each end thereof can be
attached to a cylindrical fabric tube 51 by stitching or sutures
57, as shown in FIG. 8. Jayaraman requires more than one of these
serpentine shaped connecting pieces 53 to provide longitudinal
support.
[0031] United States Patent Publication 2002/0016627 and U.S. Pat.
No. 6,312,458 to Golds each disclose a variation of a coiled
securing member 20.
[0032] A different kind of supporting member is disclosed in FIG. 8
of U.S. Pat. No. 6,053,943 to Edwin et al.
[0033] Like Jayaraman, U.S. Pat. No. 5,871,536 to Lazarus discloses
a plurality of straight, longitudinal support structures 38
attached to the circumferential support structures 36, see FIGS. 1,
6, 7, 8, 10, 11, 12, 14. FIG. 8 of Lazarus illustrates the
longitudinal support structures 38 attached to a distal structure
36 and extending almost all of the way to the proximal structure
36. The longitudinal structures 38, 84, 94 can be directly
connected to the body 22, 80 and can be telescopic 38, 64.
[0034] United States Patent Publication 2003/0088305 to Van Schie
et al. (hereinafter "Van Schie") does not disclose a support bar.
Rather, it discloses a curved stent graft using an elastic material
8 connected to stents at a proximal end 2 and at a distal end 3
(see FIGS. 1, 2) thereof to create a curved stent graft. Because
Van Schie needs to create a flexible curved graft, the elastic
material 8 is made of silicone rubber or another similar material.
Thus, the material 8 cannot provide support in the longitudinal
extent of the stent graft. Accordingly, an alternative to the
elastic support material 8 is a suture material 25 shown in FIGS. 3
to 6.
SUMMARY OF THE INVENTION
[0035] The invention provides a non-circular stent that overcomes
the hereinafore-mentioned disadvantages of the heretofore-known
devices and methods of this general type and that provides a vessel
repair device that implants/conforms more efficiently within the
natural or diseased course of the aorta by aligning with the
natural curve of the aorta, decreases the likelihood of vessel
puncture, increases the blood-tight vascular connection, retains
the intraluminal wall of the vessel position, is more resistant to
migration, and delivers the stent graft into a curved vessel while
minimizing intraluminal forces imparted during delivery and while
minimizing the forces needed for a user to deliver the stent graft
into a curved vessel.
[0036] With the foregoing and other objects in view, there is
provided, in accordance with the invention, a vascular repair
device, including a tubular graft body having a central
longitudinal axis and a structural framework having at least one
stent connected to the graft body in a partially compressed state,
the stent having substantially linear struts and apices between
adjacent pairs of the struts, each of the apices being in the same
plane as the adjacent pairs of the struts.
[0037] With the objects of the invention in view, there is also
provided a vascular repair device, including a tubular graft body
having a longitudinal axis and a structural framework having at
least one stent connected to the graft body in a partially
compressed state, the stent having a polygonal profile orthogonal
to the longitudinal axis.
[0038] With the objects of the invention in view, there is also
provided a vascular repair device, including a tubular graft body
having a longitudinal axis and a structural framework having at
least one Z-stent connected to the graft body in a partially
compressed state, the Z-stent having substantially linear struts
and apices between adjacent pairs of the struts, each of the apices
being in the same plane as the adjacent pairs of the struts.
[0039] With the objects of the invention in view, in a vascular
repair device having a tubular graft body with a longitudinal axis,
there is also provided a structural framework including at least
one stent connected to the graft body, the stent having a polygonal
profile orthogonal to the longitudinal axis.
[0040] In accordance with another feature of the invention, the
stent is a Z-stent. The stent can have between 10 and 20 apices.
The apices can be curved or angular.
[0041] With the objects of the invention in view, there is also
provided a vascular repair device, including a tubular graft body
having a central longitudinal axis and a structural framework
having at least one stent connected to the graft body, the stent
defining a cross plane orthogonal to the longitudinal axis and a
cross profile parallel to the cross-sectional plane and viewed
along the longitudinal axis, the cross profile having a polygonal
shape.
[0042] With the objects of the invention in view, there is also
provided a vascular repair device, including a tubular graft body
having a longitudinal axis and a structural framework having at
least one Z-stent connected to the graft body in a partially
compressed state, the Z-stent having a polygonal profile orthogonal
to the longitudinal axis, the polygonal profile being a shape
selected from one of the group consisting of a decagon, an
undecagon, a dodecagon, a tridecagon, a tetradecagon, a
pentadecagon, a hexadecagon, a heptadecagon, a octadecagon, an
enneadecagon, and an icosagon.
[0043] In accordance with a further feature of the invention, the
stent defines a cross profile orthogonal to the longitudinal axis
and the cross profile has a polygonal shape selected from one of
the group consisting of a decagon, an undecagon, a dodecagon, a
tridecagon, a tetradecagon, a pentadecagon, a hexadecagon, a
heptadecagon, a octadecagon, an enneadecagon, and an icosagon.
[0044] In accordance with an added feature of the invention, the at
least one stent is a plurality of stents. The plurality of stents
is independently connected to the graft body. In a particular
embodiment, the stents are independently connected to the graft
body without touching one another.
[0045] In accordance with an additional feature of the invention,
the plurality of stents includes at least one bare stent.
[0046] In accordance with yet another feature of the invention, the
stent is sewn to the graft body.
[0047] In accordance with yet a further feature of the invention,
the graft body has exterior and interior surfaces and the at least
one stent is sewn to at least one of the exterior surface and the
interior surface.
[0048] In accordance with yet an added feature of the invention,
the stents define a proximal-most stent, a distal-most stent, and a
bare stent connected to the interior surface and a remainder of the
stents is connected to the exterior surface.
[0049] In accordance with yet an additional feature of the
invention, the graft body has an internal diameter and the stent
has an internal at-rest diameter larger than the internal
diameter.
[0050] In accordance with a concomitant feature of the invention,
the stent is a wire of a material having a shape memory. The
material is selected from at least one of a group consisting of
nitinol, stainless steel, biopolymers, cobalt chrome alloy, and
titanium alloy.
[0051] Other features that are considered as characteristic for the
invention are set forth in the appended claims.
[0052] Although the invention is illustrated and described herein
as embodied in a non-circular stent, it is, nevertheless, not
intended to be limited to the details shown because various
modifications and structural changes may be made therein without
departing from the spirit of the invention and within the scope and
range of equivalents of the claims.
[0053] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof,
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] The features of the present invention, which are believed to
be novel, are set forth with particularity in the appended claims.
The invention, together with further objects and advantages
thereof, may best be understood by reference to the following
description, taken in conjunction with the accompanying drawings,
in the several figures of which like reference numerals identify
like elements, and in which:
[0055] FIG. 1 is a side elevational view of a stent graft according
to the invention;
[0056] FIG. 2 is a side elevational view of a stent of the stent
graft of FIG. 1;
[0057] FIG. 3 is a cross-sectional view of the stent of FIG. 2 with
different embodiments of protrusions;
[0058] FIG. 4 is a perspective view of a prior art round mandrel
for forming prior art stents;
[0059] FIG. 5 is a fragmentary, side elevational view of a prior
art stent in a portion of a vessel;
[0060] FIG. 6 is a perspective view of a dodecahedral-shaped
mandrel for forming stents in FIGS. 1 to 3;
[0061] FIG. 7 is a fragmentary, side elevational view of the stent
of FIGS. 1 to 3 in a portion of a vessel;
[0062] FIG. 8 is a fragmentary, enlarged side elevational view of
the proximal end of the stent graft of FIG. 1 illustrating movement
of a gimbaled end;
[0063] FIG. 9 is a side elevational view of a two-part stent graft
according to the invention;
[0064] FIG. 10 is a fragmentary, side elevational view of a
delivery system according to the invention with a locking ring in a
neutral position;
[0065] FIG. 11 is a fragmentary, side elevational view of the
delivery system of FIG. 10 with the locking ring in an advancement
position and, as indicated by dashed lines, a distal handle and
sheath assembly in an advanced position;
[0066] FIG. 12 is a fragmentary, enlarged view of a sheath assembly
of the delivery system of FIG. 10;
[0067] FIG. 13 is a fragmentary, enlarged view of an apex capture
device of the delivery system of FIG. 10 in a captured
position;
[0068] FIG. 14 is a fragmentary, enlarged view of the apex capture
device of FIG. 13 in a released position;
[0069] FIG. 15 is a fragmentary, enlarged view of an apex release
assembly of the delivery system of FIG. 10 in the captured
position;
[0070] FIG. 16 is a fragmentary, enlarged view of the apex release
assembly of FIG. 15 in the captured position with an intermediate
part removed;
[0071] FIG. 17 is a fragmentary, enlarged view of the apex release
assembly of FIG. 16 in the released position;
[0072] FIG. 18 is a fragmentary, side elevational view of the
delivery system of FIG. 11 showing how a user deploys the
prosthesis;
[0073] FIG. 19 is a fragmentary cross-sectional view of human
arteries including the aorta with the assembly of the present
invention in a first step of a method for inserting the prosthesis
according to the invention;
[0074] FIG. 20 is a fragmentary cross-sectional view of the
arteries of FIG. 19 with the assembly in a subsequent step of the
method for inserting the prosthesis;
[0075] FIG. 21 is a fragmentary cross-sectional view of the
arteries of FIG. 20 with the assembly in a subsequent step of the
method for inserting the prosthesis;
[0076] FIG. 22 is a fragmentary cross-sectional view of the
arteries of FIG. 21 with the assembly in a subsequent step of the
method for inserting the prosthesis;
[0077] FIG. 23 is a fragmentary cross-sectional view of the
arteries of FIG. 22 with the assembly in a subsequent step of the
method for inserting the prosthesis;
[0078] FIG. 24 is a fragmentary cross-sectional view of the
arteries of FIG. 23 with the assembly in a subsequent step of the
method for inserting the prosthesis;
[0079] FIG. 25 is a fragmentary, diagrammatic, perspective view of
the coaxial relationship of delivery system lumen according to the
invention;
[0080] FIG. 26 is a fragmentary, cross-sectional view of the apex
release assembly according to the invention;
[0081] FIG. 27 is a fragmentary, side elevational view of the stent
graft of FIG. 1 with various orientations of radiopaque markers
according to the invention;
[0082] FIG. 28 is a fragmentary perspective view of the stent graft
of FIG. 1 with various orientations of radiopaque markers according
to the invention;
[0083] FIG. 29 is a perspective view of a distal apex head of the
apex capture device of FIG. 13;
[0084] FIG. 30 is a fragmentary side elevational view of the distal
apex head of FIG. 29 and a proximal apex body of the apex capture
device of FIG. 13 with portions of a bare stent in the captured
position;
[0085] FIG. 31 is a fragmentary, side elevational view of the
distal apex head and proximal apex body of FIG. 30 with a portion
of the proximal apex body cut away to illustrate the bare stent in
the captured position;
[0086] FIG. 32 is a fragmentary side elevational view of the distal
apex head and proximal apex body of FIG. 30 in the released
position;
[0087] FIG. 33 is a fragmentary, cross-sectional view of an
embodiment of handle assemblies according to the invention;
[0088] FIG. 34 is a cross-sectional view of a pusher clasp rotator
of the handle assembly of FIG. 33;
[0089] FIG. 35 is a plan view of the pusher clasp rotator of FIG.
34 viewed along line C-C;
[0090] FIG. 36 is a plan and partially hidden view of the pusher
clasp rotator of FIG. 34 with a helix groove for a first embodiment
of the handle assembly of FIGS. 10, 11, and 18;
[0091] FIG. 37 is a cross-sectional view of the pusher clasp
rotator of FIG. 36 along section line A-A;
[0092] FIG. 38 is a plan and partially hidden view of the pusher
clasp rotator of FIG. 36;
[0093] FIG. 39 is a cross-sectional view of the pusher clasp
rotator of FIG. 38 along section line B-B;
[0094] FIG. 40 is a perspective view of a rotator body of the
handle assembly of FIG. 33;
[0095] FIG. 41 is an elevational and partially hidden side view of
the rotator body of FIG. 40;
[0096] FIG. 42 is a cross-sectional view of the rotator body of
FIG. 41 along section line A-A;
[0097] FIG. 43 is an elevational and partially hidden side view of
the rotator body of FIG. 40;
[0098] FIG. 44 is an elevational and partially hidden side view of
a pusher clasp body of the handle assembly of FIG. 33;
[0099] FIG. 45 is a cross-sectional view of the pusher clasp body
of FIG. 44 along section line A-A;
[0100] FIG. 46 is a cross-sectional view of the pusher clasp body
of FIG. 44 along section line B-B;
[0101] FIG. 47 is a fragmentary, side elevational view of a portion
of the handle assembly of FIG. 33 with a sheath assembly according
to the invention;
[0102] FIG. 48 is an exploded side elevational view of a portion of
the handle assembly of FIG. 47;
[0103] FIG. 49 is a fragmentary elevational and partially hidden
side view of a handle body of the handle assembly of FIG. 33;
[0104] FIG. 50 is a fragmentary, exploded side elevational view of
a portion of a second embodiment of the handle assembly according
to the invention;
[0105] FIG. 51 is a fragmentary, side elevational view of the
portion of FIG. 50 in a neutral position;
[0106] FIG. 52 is an exploded view of a first portion of the second
embodiment of the handle assembly;
[0107] FIG. 53 is a fragmentary, exploded view of a larger portion
of the second embodiment of the handle assembly as compared to FIG.
52 with the first portion and the sheath assembly;
[0108] FIG. 54 is perspective view of a clasp body of the second
embodiment of the handle assembly;
[0109] FIG. 55 is an elevational side view of the clasp body of
FIG. 54;
[0110] FIG. 56 is a cross-sectional view of the clasp body of FIG.
55 along section line A-A;
[0111] FIG. 57 is a plan view of the clasp body of FIG. 54;
[0112] FIG. 58 is a plan view of the clasp body of FIG. 57 viewed
from section line B-B;
[0113] FIG. 59 is a fragmentary and partially hidden side
elevational view of a clasp sleeve of the second embodiment of the
handle assembly;
[0114] FIG. 60 is a fragmentary, cross-sectional view of a portion
the clasp sleeve of FIG. 59 along section line A;
[0115] FIG. 61 is a fragmentary, cross-sectional view of the clasp
sleeve of FIG. 59 along section line C-C;
[0116] FIG. 62 is a fragmentary and partially hidden side
elevational view of the clasp sleeve of FIG. 59 rotated with
respect to FIG. 59; and
[0117] FIG. 63 is a fragmentary, cross-sectional view of the nose
cone and sheath assemblies of FIG. 10.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0118] While the specification concludes with claims defining the
features of the invention that are regarded as novel, it is
believed that the invention will be better understood from a
consideration of the following description in conjunction with the
drawing figures, in which like reference numerals are carried
forward.
[0119] The present invention provides a stent graft and delivery
system that treats, in particular, thoracic aortic defects from the
brachiocephalic level of the aortic arch distally to a level just
superior to the celiac axis and provides an endovascular foundation
for an anastomosis with the thoracic aorta, while providing an
alternative method for partial/total thoracic aortic repair by
excluding the vessel defect and making surgical repair of the aorta
unnecessary. The stent graft of the present invention, however, is
not limited to use in the aorta. It can be endoluminally inserted
in any accessible artery that could accommodate the stent graft's
dimensions.
[0120] Stent Graft
[0121] The stent graft according to the present invention provides
various features that, heretofore, have not been applied in the art
and, thereby, provide a vessel repair device that implants/conforms
more efficiently within the natural or diseased course of the
aorta, decreases the likelihood of vessel puncture, and increases
the blood-tight vascular connection, and decreases the probability
of graft mobility.
[0122] The stent graft is implanted endovascularly before or during
or in place of an open repair of the vessel (i.e., an arch, in
particular, the ascending and/or descending portion of the aorta)
through a delivery system described in detail below. The typical
defects treated by the stent graft are aortic aneurysms, aortic
dissections, and other diseases such as penetrating aortic ulcer,
coarctation, and patent ductus arteriosus, related to the aorta.
When endovascularly placed in the aorta, the stent graft forms a
seal in the vessel and automatically affixes itself to the vessel
with resultant effacement of the pathological lesion.
[0123] Referring now to the figures of the drawings in detail and
first, particularly to FIG. 1 thereof, there is shown an improved
stent graft 1 having a graft sleeve 10 and a number of stents 20.
These stents 20 are, preferably, made of nitinol, an alloy having
particularly special properties allowing it to rebound to a set
configuration after compression, the rebounding property being
based upon the temperature at which the alloy exists. For a
detailed explanation of nitinol and its application with regard to
stents, see, e.g., U.S. Pat. Nos. 4,665,906, 5,067,957, and
5,597,378 to Jervis and to Gianturco.
[0124] The graft sleeve 10 is cylindrical in shape and is made of a
woven graft material along its entire length. The graft material
is, preferably, polyester, in particular, polyester referred to
under the name DACRON.RTM. or other material types like Expanded
Polytetrafluoroethylene ("EPTFE"), or other polymeric based
coverings. The tubular graft sleeve 10 has a framework of
individual lumen-supporting wires each referred to in the art as a
stent 20. Connection of each stent 20 is, preferably, performed by
sewing a polymeric (nylon, polyester) thread around an entirety of
the stent 20 and through the graft sleeve 10. The stitch spacings
are sufficiently close to prevent any edge of the stent 20 from
extending substantially further from the outer circumference of the
graft sleeve 10 than the diameter of the wire itself. Preferably,
the stitches have a 0.5 mm to 5 mm spacing.
[0125] The stents 20 are sewn either to the exterior or interior
surfaces of the graft sleeve 10. FIG. 1 illustrates all stents 20,
30 on the exterior surface 16 of the graft sleeve 10. In a
preferred non-illustrated embodiment, the most proximal 23 and
distal stents and a bare stent 30 are connected to the interior
surface of the graft sleeve 10 and the remainder of the stents 20
are connected to the exterior surface 16. Another possible
non-illustrated embodiment alternates connection of the stents 20,
30 to the graft sleeve 10 from the graft exterior surface to the
graft interior surface, the alternation having any periodic
sequence.
[0126] A stent 20, when connected to the graft sleeve 10, radially
forces the graft sleeve 10 open to a predetermined diameter D. The
released radial force creates a seal with the vessel wall and
affixes the graft to the vessel wall when the graft is implanted in
the vessel and is allowed to expand.
[0127] Typically, the stents 20 are sized to fully expand to the
diameter D of the fully expanded graft sleeve 10. However, a
characteristic of the present invention is that each of the stents
20 and 30 has a diameter larger than the diameter D of the fully
expanded graft sleeve 10. Thus, when the stent graft 1 is fully
expanded and resting on the internal surface of the vessel where it
has been placed, each stent 20 is imparting independently a
radially directed force to the graft sleeve 10. Such
pre-compression, as it is referred to herein, is applied (1) to
ensure that the graft covering is fully extended, (2) to ensure
sufficient stent radial force to make sure sealing occurs, (3) to
affix the stent graft and prevent it from kinking, and (4) to affix
the stent graft and prevent migration.
[0128] Preferably, each of the stents 20 is formed with a single
nitinol wire. Of course other biocompatible materials can be used,
for example, stainless steel, biopolymers, cobalt chrome, and
titanium alloys.
[0129] The preferred shape of each stent 20 corresponds to what is
referred in the art as a Z-stent, see, e.g., Gianturco (although
the shape of the stents 20 can be in any form that satisfies the
functions of a self-expanding stent). Thus, the wire forming the
stent 20 is a ring having a wavy or sinusoidal shape. In
particular, an elevational view orthogonal to the center axis 21 of
the stent 20 reveals a shape somewhere between a triangular wave
and a sinusoidal wave as shown in FIG. 2. In other words, the view
of FIG. 2 shows that the stents 20 each have alternating proximal
22 and distal 24 apices. Preferably, the apices have a radius r
that does not present too great of a point towards a vessel wall to
prevent any possibility of puncturing the vessel, regardless of the
complete circumferential connection to the graft sleeve 10. In
particular, the radius r of curvature of the proximal 22 and distal
24 apices of the stent 20 are, preferably, equal. The radius of
curvature r is between approximately 0.1 mm and approximately 3.0
mm, in particular, approximately 0.5 mm.
[0130] Another advantageous feature of a stent lies in extending
the longitudinal profile along which the stent contacts the inner
wall of a vessel. This longitudinal profile can be explained with
reference to FIGS. 3 to 7.
[0131] Prior art stents and stents according to the present
invention are formed on mandrels 29, 29' by winding the wire around
the mandrel 29, 29' and forming the apexes 22, 24, 32, 34 by
wrapping the wire over non-illustrated pins that protrude
perpendicular from the axis of the mandrel. Such pins, if
illustrated, would be located in the holes illustrated in the
mandrels 29, 29' of FIGS. 4 and 6. Prior art stents are formed on a
round mandrel 29 (also referred to as a bar). A stent 20' formed on
a round mandrel 29 has a profile that is rounded (see FIG. 5).
Because of the rounded profile, the stent 20' does not conform
evenly against the inner wall of the vessel 2 in which it is
inserted. This disadvantage is critical in the area of stent graft
1 seal zones--areas where the ends of the graft 10 need to be laid
against the inner wall of the vessel 2. Clinical experience reveals
that stents 20' formed with the round mandrel 29 do not lie against
the vessel 2; instead, only a mid-section of the stent 20' rests
against the vessel 2, as shown in FIG. 5. Accordingly, when such a
stent 20' is present at either of the proximal 12 or distal 14 ends
of the stent graft 1, the graft material flares away from the wall
of the vessel 2 into the lumen--a condition that is to be avoided.
An example of this flaring can be seen by comparing the upper and
lower portions of the curved longitudinal profile of the stent 20'
in FIG. 5 with the linear longitudinal profile of the vessel 2.
[0132] To remedy this problem and ensure co-columnar apposition of
the stent and vessel, stents 20 of the present invention are formed
on a multiple-sided mandrel. In particular, the stents 20 are
formed on a polygonal-shaped mandrel 29'. The mandrel 29' does not
have sharp edges. Instead, it has flat sections and rounded edge
portions between the respective flat sections. Thus, a stent formed
on the mandrel 29' will have a cross-section that is somewhat round
but polygonal, as shown in FIG. 3. The cross-sectional view
orthogonal to the center axis 21 of such a stent 20 will have
beveled or rounded edges 31 (corresponding to the rounded edge
portions of the mandrel 29') disposed between flat sides or struts
33 (corresponding to the flat sections of the mandrel 29'). With
stents manufactured in this way, the apices remain on the
circumference of the graft and do not bend into the graft interior
like prior art stents--an undesirable condition as explained in the
preceding paragraph. Further, the struts of the stents so
manufactured (the substantially linear portions of the stent
between the apices) lie in the plane of the graft material when
attached thereto as shown in FIG. 7. In contrast, prior art struts
are curved (see FIG. 5) and, therefore, force the graft material
inwards away from the vessel wall. As used herein, substantially
linear means that the struts are sufficiently straight and level to
substantially prevent displacement of an apex (which lies between
two adjacent struts) towards the interior of the graft material to
which the struts and apices are attached.
[0133] To manufacture the stent 20, apexes of the stents 20 are
formed by winding the wire over non-illustrated pins located on the
rounded portions of the mandrel 29'. Thus, the struts 33 lying
between the apexes 22, 24, 32, 34 of the stents 20 lie flat against
the flat sides of the mandrel 29'. When so formed on the inventive
mandrel 29', the longitudinal profile is substantially less rounded
than the profile of stent 20' and, in practice, is substantially
linear.
[0134] For stents 20 having six proximal 22 and six distal 24
apices, the stents 20 are formed on a dodecahedron-shaped mandrel
29' (a mandrel having twelve sides), which mandrel 29' is shown in
FIG. 6. A stent 20 formed on such a mandrel 29' will have the
cross-section illustrated in FIG. 3.
[0135] The fourteen-apex stent 20 shown in FIG. 7 illustrates a
stent 20 that has been formed on a fourteen-sided mandrel. The
stent 20 in FIG. 7 is polygonal in cross-section (having fourteen
sides) and, as shown in FIG. 7, has a substantially linear
longitudinal profile. Clinically, the linear longitudinal profile
improves the stent's 20 ability to conform to the vessel 2 and
press the graft sleeve 10 outward in the sealing zones at the
extremities of the individual stent 20.
[0136] Another way to improve the performance of the stent graft 1
is to provide the distal-most stent 25 on the graft 10 (i.e.,
downstream) with additional apices and to give it a longer
longitudinal length (i.e., greater amplitude) and/or a longer
circumferential length. When a stent 25 having a longer
circumferential length is sewn to a graft, the stent graft 1 will
perform better clinically. The improvement, in part, is due to a
need for the distal portion of the graft material 10 to be pressed
firmly against the wall of the vessel. The additional apices result
in additional points of contact between the stent graft 1 and
vessel wall, thus ensuring better apposition to the wall of the
vessel and better sealing of the graft material 10 to the vessel.
The increased apposition and sealing substantially improves the
axial alignment of the distal end 14 of the stent graft 1 to the
vessel. As set forth above, each of the stents 20 and 30 has a
diameter larger than the diameter D of the fully expanded graft
sleeve 10. Thus, if the distal stent 25 also has a diameter larger
than the diameter D, it will impart a greater radial bias on all
360 degrees of the corresponding section of the graft than stents
not having such an oversized configuration.
[0137] A typical implanted stent graft 1 typically does not
experience a lifting off at straight portions of a vessel because
the radial bias of the stents acting upon the graft sleeve give
adequate pressure to align the stent and graft sleeve with the
vessel wall. However, when a typical stent graft is implanted in a
curved vessel (such as the aorta), the distal end of the stent
graft 1 does experience a lift off from the vessel wall. The
increased apposition and sealing of the stent graft 1 according to
the present invention substantially decreases the probability of
lift off because the added height and additional apices enhance the
alignment of the stent graft perpendicular to the vessel wall as
compared to prior art stent grafts (no lift off occurs).
[0138] The number of total apices of a stent is dependent upon the
diameter of the vessel in which the stent graft 1 is to be
implanted. Vessels having a smaller diameter have a smaller total
number of apices than a stent to be implanted in a vessel having a
larger diameter. Table 1 below indicates preferred stent
embodiments for vessels having different diameters. For example, if
a vessel has a 26 or 27 mm diameter, then a preferred diameter of
the graft sleeve 10 is 30 mm. For a 30 mm diameter graft sleeve,
the intermediate stents 20 will have 5 apices on each side
(proximal and distal) for a total of 10 apices. In other words, the
stent defines 5 periodic "waves." The distal-most stent 25, in
comparison, defines 6 periodic "waves" and, therefore, has 12 total
apices. It is noted that the distal-most stent 25 in FIG. 1 does
not have the additional apex. While Table 1 indicates preferred
embodiments, these configurations can be adjusted or changed as
needed. TABLE-US-00001 TABLE 1 Stent Apices/Side Vessel Graft
(Distal-most Diameter (mm) Diameter (mm) Stent #) 19 22 5(5) 20-21
24 5(5) 22-23 26 5(5) 24-25 28 5(6) 26-27 30 5(6) 28-29 32 6(7)
30-31 34 6(7) 32-33 36 6(7) 34 38 6(7) 35-36 40 7(8) 37-38 42 7(8)
39-40 44 7(8) 41-42 46 7(8)
[0139] To increase the security of the stent graft 1 in a vessel,
an exposed or bare stent 30 is provided on the stent graft 1,
preferably, only at the proximal end 12 of the graft sleeve
10--proximal meaning that it is attached to the portion of the
graft sleeve 10 from which the blood flows into the sleeve, i.e.,
blood flows from the bare stent 30 and through the sleeve 10 to the
left of FIG. 1. The bare stent 30 is not limited to being attached
at the proximal end 12. Another non-illustrated bare stent can be
attached similarly to the distal end 14 of the graft sleeve 10.
[0140] Significantly, the bare stent 30 is only partially attached
to the graft sleeve 10. Specifically, the bare stent 30 is fixed to
the graft sleeve 10 only at the distal apices 34 of the bare stent
30. Thus, the bare stent 30 is partially free to extend the
proximal apices 32 away from the proximal end of the graft sleeve
10.
[0141] The bare stent 30 has various properties, the primary one
being to improve the apposition of the graft material to the
contour of the vessel wall and to align the proximal portion of the
graft covering in the lumen of the arch and provide a blood-tight
closure of the proximal end 12 of the graft sleeve 10 so that blood
does not pass between the vascular inside wall and outer surface 16
of the sleeve 10 (endoleak).
[0142] The preferred configuration for the radius of curvature
.alpha. of the distal apices 34 is substantially equal to the
radius r of the proximal 22 and distal 24 apices of the stent 20,
in particular, it is equal at least to the radius of curvature r of
the proximal apices of the stent 20 directly adjacent the bare
stent 30. Thus, as shown in FIG. 8, a distance between the proximal
apices 22 of the most proximal stent 23 and crossing points of the
exposed portions of the bare stent 30 are substantially at a same
distance from one another all the way around the circumference of
the proximal end 12 of the graft sleeve 10. Preferably, this
distance varies based upon the graft diameter. Accordingly, the
sinusoidal portion of the distal apices 34 connected to the graft
sleeve 10 traverse substantially the same path as that of the stent
23 closest to the bare stent 30. Thus, the distance d between the
stent 22 and all portions of the bare stent 30 connected to the
graft sleeve 10 remain constant. Such a configuration is
advantageous because it maintains the symmetry of radial force of
the device about the circumference of the vessel and also aids in
the synchronous, simultaneous expansion of the device, thus
increasing apposition of the graft material to the vessel wall to
induce a proximal seal--and substantially improve the proximal
seal--due to increasing outward force members in contact with the
vessel wall.
[0143] Inter-positioning the stents 23, 30 in phase with one
another, creates an overlap, i.e., the apices 34 of the bare stent
30 are positioned within the troughs of the stent 23. A further
advantage of such a configuration is that the overlap provides
twice as many points of contact between the proximal opening of the
graft 10 and the vessel in which the stent graft 1 is implanted.
The additional apposition points keep the proximal opening of the
graft sleeve 10 open against the vessel wall, which substantially
reduces the potential for endoleaks. In addition, the overlap of
the stents 23, 30 increases the radial load or resistance to
compression, which functionally increases fixation and reduces the
potential for device migration.
[0144] In contrast to the distal apices 34 of the bare stent 30,
the radius of curvature .beta. of the proximal apices 32 (those
apices that are not sewn into the graft sleeve 10) is significantly
larger than the radius of curvature .alpha. of the distal apices
34. A preferred configuration for the bare stent apices has a
radius approximately equal to 1.5 mm for the proximal apices 32 and
approximately equal to 0.5 mm for the distal apices 34. Such a
configuration substantially prevents perforation of the blood
vessel by the proximal apices 34, or, at a minimum, makes is much
less likely for the bare stent 30 to perforate the vessel because
of the less-sharp curvature of the proximal apices 32.
[0145] The bare stent 30 also has an amplitude greater than the
other stents 20. Preferably, the peak-to-peak amplitude of the
stents 20 is approximately 1.3 cm to 1.5 cm, whereas the
peak-to-peak amplitude of the bare stent 30 is approximately 2.5 cm
to 4.0 cm. Accordingly, the force exerted by the bare stent 30 on
the inner wall of the aorta (due to the bare stent 30 expanding to
its native position) is spread over a larger surface area. Thus,
the bare stent 30 of the present invention presents a less
traumatic radial stress to the interior of the vessel wall--a
characteristic that, while less per square mm than an individual
one of the stents 20 would be, is sufficient, nonetheless, to
retain the proximal end 12 in position. Simultaneously, the taller
configuration of the bare stent 30 guides the proximal opening of
the stent graft in a more "squared-off" manner. Thus, the proximal
opening of the stent graft is more aligned with the natural
curvature of the vessel in the area of the proximal opening.
[0146] As set forth above, because the vessel moves constantly, and
due to the constantly changing pressure imparted by blood flow, any
stent graft placed in the vessel has the natural tendency to
migrate downstream. This is especially true when the stent graft 1
has graft sleeve segments 18 with lengths defined by the separation
of the stents on either end of the segment 18, giving the stent
graft 1 an accordion, concertina, or caterpillar-like shape. When
such a shape is pulsating with the vessel and while hemodynamic
pressure is imparted in a pulsating manner along the stent graft
from the proximal end 12 to the downstream distal end 14, the stent
graft 1 has a tendency to migrate downstream in the vessel. It is
desired to have such motion be entirely prohibited.
[0147] Support along a longitudinal extent of the graft sleeve 10
assists in preventing such movement. Accordingly, as set forth
above, prior art stent grafts have provided longitudinal rods
extending in a straight line from one stent to another.
[0148] The present invention, however, provides a longitudinal,
spiraling/helical support member 40 that, while extending
relatively parallel to the longitudinal axis 11 of the graft sleeve
10, is not aligned substantially parallel to a longitudinal extent
of the entirety of the stent graft 1 as done in the prior art.
"Relatively parallel" is referred to herein as an extent that is
more along the longitudinal axis 11 of the stent graft 1 than along
an axis perpendicular thereto.
[0149] Specifically, the longitudinal support member 40 has a
somewhat S-turn shape, in that, a proximal portion 42 is relatively
parallel to the axis 11 of the graft sleeve 10 at a first degree 41
(being defined as a degree of the 360 degrees of the circumference
of the graft sleeve 10), and a distal portion 44 is, also,
relatively parallel to the axis 11 of the tube graft, but at a
different second degree 43 on the circumference of the graft sleeve
10. The difference between the first and second degrees 41, 43 is
dependent upon the length L of the graft sleeve 10. For an
approximately 20 cm (approx. 8'') graft sleeve, for example, the
second degree 43 is between 80 and 110 degrees away from the first
degree 41, in particular, approximately 90 degrees away. In
comparison, for an approximately 9 cm (approx. 3.5'') graft sleeve,
the second degree 43 is between 30 and 60 degrees away from the
first degree 41, in particular, approximately 45 degrees away. As
set forth below, the distance between the first and second degrees
41, 43 is also dependent upon the curvature and the kind of
curvature that the stent graft 1 will be exposed to when in
vivo.
[0150] The longitudinal support member 40 has a curved intermediate
portion 46 between the proximal and distal portions 42, 44. By
using the word "portion" it is not intended to mean that the rod is
in three separate parts (of course, in a particular configuration,
a multi-part embodiment is possible). A preferred embodiment of the
longitudinal support member 40 is a single, one-piece rod made of
stainless steel, cobalt chrome, nitinol, or polymeric material that
is shaped as a fully curved helix 42, 44, 46 without any straight
portion. In an alternative stent graft embodiment, the proximal and
distal portions 42, 44 can be substantially parallel to the axis 11
of the stent graft 1 and the central portion 46 can be helically
curved.
[0151] One way to describe the preferred curvature embodiment of
the longitudinal support member 40 can be using an analogy of
asymptotes. If there are two asymptotes extending parallel to the
longitudinal axis 11 of the graft sleeve 10 at the first and second
degrees 41, 43 on the graft sleeve 10, then the proximal portion 42
can be on the first degree 41 or extend approximately
asymptotically to the first degree 41 and the distal portion 44 can
be on the second degree 43 or extend approximately asymptotically
to the second degree 43. Because the longitudinal support member 40
is one piece in a preferred embodiment, the curved portion 46
follows the natural curve formed by placing the proximal and distal
portions 42, 44 as set forth herein.
[0152] In such a position, the curved longitudinal support member
40 has a centerline 45 (parallel to the longitudinal axis 11 of the
graft sleeve 10 halfway between the first and second degrees 41, 43
on the graft sleeve 10). In this embodiment, therefore, the curved
portion intersects the centerline 45 at approximately 20 to 40
degrees in magnitude, preferably at approximately 30 to 35
degrees.
[0153] Another way to describe the curvature of the longitudinal
support member can be with respect to the centerline 45. The
portion of the longitudinal support member 40 between the first
degree 41 and the centerline 45 is approximately a mirror image of
the portion of the longitudinal support member 40 between the
second degree 43 and the centerline 45, but rotated 180 degrees
around an axis orthogonal to the centerline 45. Such symmetry can
be referred to herein as "reverse-mirror symmetrical."
[0154] The longitudinal support member 40 is, preferably, sewn to
the graft sleeve 10 in the same way as the stents 20. However, the
longitudinal support member 40 is not sewn directly to any of the
stents 20 in the proximal portions of the graft. In other words,
the longitudinal support member 40 is independent of the proximal
skeleton formed by the stents 20. Such a configuration is
advantageous because an independent proximal end creates a gimbal
that endows the stent graft with additional flexibility.
Specifically, the gimbaled proximal end allows the proximal end to
align better to the proximal point of apposition, thus reducing the
chance for endoleak. The additional independence from the
longitudinal support member allows the proximal fixation point to
be independent from the distal section that is undergoing related
motion due to the physiological motion of pulsutile flow of blood.
Also in a preferred embodiment, the longitudinal support member 40
is pre-formed in the desired spiral/helical shape
(counter-clockwise from proximal to distal), before being attached
to the graft sleeve 10.
[0155] Because vessels receiving the stent graft 1 are not
typically straight, the final implanted position of the stent graft
1 will, most likely, be curved in some way. In prior art stent
grafts (which only provide longitudinally parallel support rods),
there exist, inherently, a force that urges the rod, and, thereby,
the entire stent graft, to the straightened, natural shape of the
rod. This force is disadvantageous for stent grafts that are to be
installed in an at least partly curved manner.
[0156] The curved shape of the longitudinal support member 40
according to the present invention eliminates at least a majority,
or substantially all, of this disadvantage because the longitudinal
support member's 40 natural shape is curved, and, therefore,
imparts less of a force, or none at all, to straighten the
longitudinal support member 40, and, thereby, move the implanted
stent graft in an undesirable way. At the same time, the curved
longitudinal support member 40 negates the effect of the latent
kinetic force residing in the aortic wall that is generated by the
propagation of the pulse wave and systolic blood pressure in the
cardiac cycle, which is, then, released during diastole.
[0157] In a preferred embodiment, the longitudinal support member
40 can be curved in a patient-customized way to accommodate the
anticipated curve of the actual vessel in which the graft will be
implanted. Thus, the distance between the first and second degrees
41, 43 will be dependent upon the curvature and the kind of
curvature that the stent graft 1 will be exposed to when in vivo.
As such, when implanted, the curved longitudinal support member 40
will, actually, exhibit an opposite force against any environment
that would alter its conformance to the shape of its resident
vessel's existing course(es).
[0158] Preferably, the support member 40 is sewn, in a similar
manner as the stents 20, on the outside surface 16 of the graft
sleeve 10.
[0159] In prior art support rods, the ends thereof are merely a
terminating end of a steel or nitinol rod and are, therefore,
sharp. Even though these ends are sewn to the tube graft in the
prior art, the possibility of tearing the vessel wall still exists.
It is, therefore, desirable to not provide the support rod with
sharp ends that could puncture the vessel in which the stent graft
is placed.
[0160] The two ends of the longitudinal support member 40 of the
present invention do not end abruptly. Instead, each end of the
longitudinal support member loops 47 back upon itself such that the
end of the longitudinal support member along the axis of the stent
graft is not sharp and, instead, presents an exterior of a circular
or oval shape when viewed from the ends 12, 14 of the graft sleeve
10. Such a configuration substantially prevents the possibility of
tearing the vessel wall and also provides additional longitudinal
support at the oval shape by having two longitudinally extending
sides of the oval 47.
[0161] In addition, in another embodiment, the end of the
longitudinal support member may be connected to the second proximal
stent 28 and to the most distal stent. This configuration would
allow the longitudinal support member to be affixed to stent 28
(see FIG. 1) and the most distal stent for support while still
allowing for the gimbaled feature of the proximal end of the stent
graft to be maintained.
[0162] A significant feature of the longitudinal support member 40
is that the ends of the longitudinal support member 40 may not
extend all the way to the two ends 12, 14 of the graft sleeve 10.
Instead, the longitudinal support member 40 terminates at or prior
to the second-to-last stent 28 at the proximal end 12, and, if
desired, prior to the second-to-last stent 28' at the distal end 14
of the graft sleeve 10. Such an ending configuration (whether
proximal only or both proximal and distal) is chosen for a
particular reason--when the longitudinal support member 40 ends
before either of the planes defined by cross-sectional lines 52,
52', the sleeve 10 and the stents 20 connected thereto respectively
form gimbaled portions 50, 50'. In other words, when a grasping
force acting upon the gimbaled ends 50, 50' moves or pivots the
cross-sectional plane defining each end opening of the graft sleeve
10 about the longitudinal axis 11 starting from the planes defined
by the cross-sectional lines 52, 52', then the moving portions 50,
50' can be oriented at any angle .gamma. about the center of the
circular opening in all directions (360 degrees), as shown in FIG.
8. The natural gimbal, thus, allows the ends 50, 50' to be inclined
in any radial direction away from the longitudinal axis 11.
[0163] Among other things, the gimbaled ends 50, 50' allow each end
opening to dynamically align naturally to the curve of the vessel
in which it is implanted. A significant advantage of the gimbaled
ends 50, 50' is that they limit propagation of the forces acting
upon the separate parts. Specifically, a force that, previously,
would act upon the entirety of the stent graft 1, in other words,
both the end portions 50, 50' and the middle portion of the stent
graft 1 (i.e., between planes 52, 52'), now principally acts upon
the portion in which the force occurs. For example, a force that
acts only upon one of the end portions 50, 50' substantially does
not propagate into the middle portion of the stent graft 1 (i.e.,
between planes 52, 52'). More significantly, however, when a force
acts upon the middle portion of the stent graft 1 (whether moving
longitudinally, axially (dilation), or in a torqued manner), the
ends 50, 50', because they are gimbaled, remain relatively
completely aligned with the natural contours of the vessel
surrounding the respective end 50, 50' and have virtually none of
the force transferred thereto, which force could potentially cause
the ends to grate, rub, or shift from their desired fixed position
in the vessel. Accordingly, the stent graft ends 50, 50' remain
fixed in the implanted position and extend the seating life of the
stent graft 1.
[0164] Another advantage of the longitudinal support member 40 is
that it increases the columnar strength of the graft stent 1.
Specifically, the material of the graft sleeve can be compressed
easily along the longitudinal axis 11, a property that remains true
even with the presence of the stents 20 so long as the stents 20
are attached to the graft sleeve 10 with a spacing between the
distal apices 24 of one stent 20 and the proximal apices 22 of the
next adjacent stent 20. This is especially true for the amount of
force imparted by the flow of blood along the extent of the
longitudinal axis 11. However, with the longitudinal support member
40 attached according to the present invention, longitudinal
strength of the stent graft 1 increases to overcome the
longitudinal forces imparted by blood flow.
[0165] Another benefit imparted by having such increased
longitudinal strength is that the stent graft 1 is further
prevented from migrating in the vessel because the tube graft is
not compressing and expanding in an accordion-like manner--movement
that would, inherently, cause graft migration.
[0166] A further measure for preventing migration of the stent
graft 1 is to equip at least one of any of the individual stents
20, 30 or the longitudinal support member 40 with protuberances 60,
such as barbs or hooks (FIG. 3). See, e.g., United States Patent
Publication 2002/0052660 to Greenhalgh. In the preferred embodiment
of the present invention, the stents 20, 30 are secured to the
outer circumferential surface 16 of the graft sleeve 10.
Accordingly, if the stents 20 (or connected portions of stent 30)
have protuberances 60 protruding outwardly, then such features
would catch the interior wall of the vessel and add to the
prevention of stent graft 1 migration. Such an embodiment can be
preferred for aneurysms but is not preferred for the fragile
characteristics of dissections because such protuberances 60 can
excoriate the inner layer(s) of the vessel and cause leaks between
layers, for example.
[0167] As shown in FIG. 9, the stent graft 1 is not limited to a
single graft sleeve 10. Instead, the entire stent graft can be a
first stent graft 100 having all of the features of the stent graft
1 described above and a second stent graft 200 that, instead of
having a circular extreme proximal end 12, as set forth above, has
a proximal end 212 with a shape following the contour of the most
proximal stent 220 and is slightly larger in circumference than the
distal circumference of the first stent graft 100. Therefore, an
insertion of the proximal end 212 of the second stent graft 200
into the distal end 114 of the first stent graft 100 results, in
total, in a two-part stent graft. Because blood flows from the
proximal end 112 of the first stent graft 100 to the distal end 214
of the second stent graft 200, it is preferable to have the first
stent graft 100 fit inside the second stent graft 200 to prevent
blood from leaking out therebetween. This configuration can be
achieved by implanting the devices in reverse order (first implant
graft 200 and, then, implant graft 100. Each of the stent grafts
100, 200 can have its own longitudinal support member 40 as
needed.
[0168] It is not significant if the stent apices of the distal-most
stent of the first stent graft 100 are not aligned with the stent
apices of the proximal-most stent 220 of the second stent graft
200. What is important is the amount of junctional overlap between
the two grafts 100, 200.
[0169] Delivery System
[0170] As set forth above, the prior art includes many different
systems for endoluminally delivering a prosthesis, in particular, a
stent graft, to a vessel. Many of the delivery systems have similar
parts and most are guided along a guidewire that is inserted,
typically, through an insertion into the femoral artery near a
patient's groin prior to use of the delivery system. To prevent
puncture of the arteries leading to and including the aorta, the
delivery system is coaxially connected to the guidewire and tracks
the course of the guidewire up to the aorta. The parts of the
delivery system that will track over the wire are, therefore, sized
to have an outside diameter smaller than the inside diameter of the
femoral artery of the patient. The delivery system components that
track over the guidewire include the stent graft and are made of a
series of coaxial lumens referred to as catheters and sheaths. The
stent graft is constrained, typically, by an outer catheter,
requiring the stent graft to be compressed to fit inside the outer
catheter. Doing so makes the portion of the delivery system that
constrains the stent graft very stiff, which, therefore, reduces
that portion's flexibility and makes it difficult for the delivery
system to track over the guidewire, especially along curved vessels
such as the aortic arch. In addition, because the stent graft
exerts very high radial forces on the constraining catheter due to
the amount that it must be compressed to fit inside the catheter,
the process of deploying the stent graft by sliding the
constraining catheter off of the stent graft requires a very high
amount of force, typically referred to as a deployment force. Also,
the catheter has to be strong enough to constrain the graft,
requiring it to be made of a rigid material. If the rigid material
is bent, such as when tracking into the aortic arch, the rigid
material tends to kink, making it difficult if not impossible to
deploy the stent graft.
[0171] Common features of vascular prosthesis delivery systems
include a tapered nose cone fixedly connected to a guidewire lumen,
which has an inner diameter substantially corresponding to an outer
diameter of the guidewire such that the guidewire lumen slides
easily over and along the guidewire. A removable, hollow catheter
covers and holds a compressed prosthesis in its hollow and the
catheter is fixedly connected to the guidewire lumen. Thus, when
the prosthesis is in a correct position for implantation, the
physician withdraws the hollow catheter to gradually expose the
self-expanding prosthesis from its proximal end towards its distal
end. When the catheter has withdrawn a sufficient distance from
each portion of the expanding framework of the prosthesis, the
framework can expand to its native position, preferably, a position
that has a diameter at least as great as the inner diameter of the
vessel wall to, thereby, tightly affix the prosthesis in the
vessel. When the catheter is entirely withdrawn from the prosthesis
and, thereby, allows the prosthesis to expand to the diameter of
the vessel, the prosthesis is fully expanded and connected
endoluminally to the vessel along the entire extent of the
prosthesis, e.g., to treat a dissection. When treating an aneurysm,
for example, the prosthesis is in contact with the vessel's
proximal and distal landing zones when completely released from the
catheter. At such a point in the delivery, the delivery system can
be withdrawn from the patient. The prosthesis, however, cannot be
reloaded in the catheter if implantation is not optimal.
[0172] The aorta usually has a relatively straight portion in the
abdominal region and in a lower part of the thoracic region.
However, in the upper part of the thoracic region, the aorta is
curved substantially, traversing an upside-down U-shape from the
back of the heart over to the front of the heart. As explained
above, prior art delivery systems are relatively hard and
inflexible (the guidewire/catheter portion of the prior art
delivery systems). Therefore, if the guidewire/catheter must
traverse the curved portion of the aorta, it will kink as it is
curved or it will press against the top portion of the aortic
curve, possibly puncturing the aorta if the diseased portion is
located where the guidewire/catheter is exerting its force. Such a
situation must be avoided at all costs because the likelihood of
patient mortality is high. The prior art does not provide any way
for substantially reducing the stress on the curved portion of the
aorta or for making the guidewire/catheter sufficiently flexible to
traverse the curved portion without causing damage to the
vessel.
[0173] The present invention, however, provides significant
features not found in the prior art that assist in placing a stent
graft in a curved portion of the aorta in a way that substantially
reduces the stress on the curved portion of the aorta and
substantially reduces the insertion forces needed to have the
compressed graft traverse the curved portion of the aorta. The
delivery system of the present invention also has a very simple to
use handle assembly. The handle assembly takes advantage of the
fact that the inside diameter of the aorta is substantially larger
that the inside diameter of the femoral arteries. The present
invention, accordingly, uses a two-stage approach in which, after
the device is inserted in through the femoral artery and tracks up
into the abdominal area of the aorta (having a larger diameter (see
FIG. 19) than the femoral artery), a second stage is deployed (see
FIG. 20) allowing a small amount of expansion of the stent graft
while still constrained in a sheath; but this sheath, made of
fabric/woven polymer or similar flexible material, is very
flexible. Such a configuration gives the delivery system greater
flexibility for tracking, reduces deployment forces because of the
larger sheath diameter, and easily overcome kinks because the
sheath is made of fabric.
[0174] To describe the delivery system of the present invention,
the method for operating the delivery assembly 600 will be
described first in association with FIGS. 10, 11, and 12.
Thereafter, the individual components will be described to allow a
better understanding of how each step in the process is effected
for delivering the stent graft 1 to any portion of the aorta 700
(see FIGS. 19 to 24), in particular, the curved portion 710 of the
aorta.
[0175] Initially, the distal end 14 of the stent graft 1 is
compressed and placed into a hollow, cup-shaped, or tubular-shaped
graft holding device, in particular, the distal sleeve 644 (see,
e.g., FIG. 25). At this point, it is noted that the convention for
indicating direction with respect to delivery systems is opposite
that of the convention for indicating direction with respect to
stent grafts. Therefore, the proximal direction of the delivery
system is that portion closest to the user/physician employing the
system and the distal direction corresponds to the portion farthest
away from the user/physician, i.e., towards the distal-most nose
cone 632.
[0176] The distal sleeve 644 is fixedly connected to the distal end
of the graft push lumen 642, which lumen 642 provides an end face
for the distal end 14 of the stent graft 1. Alternatively, the
distal sleeve 644 can be removed entirely. In such a configuration,
as shown in FIG. 12, for example, the proximal taper of the inner
sheath 652 can provide the measures for longitudinally holding the
compressed distal end of the graft 1. As set forth in more detail
below, each apex 32 of the bare stent 30 is, then, loaded into the
apex capture device 634 so that the stent graft 1 is held at both
its proximal and distal ends. The loaded distal end 14, along with
the distal sleeve 644 and the graft push lumen 642, are, in turn,
loaded into the inner sheath 652, thus, further compressing the
entirety of the stent graft 1. The captured bare stent 30, along
with the nose cone assembly 630 (including the apex capture device
634), is loaded until the proximal end of the nose cone 632 rests
on the distal end of the inner sheath 652. The entire nose cone
assembly 630 and sheath assembly 650 is, then, loaded proximally
into the rigid outer catheter 660, further compressing the stent
graft 1 (resting inside the inner sheath 652) to its fully
compressed position for later insertion into a patient. See FIG.
63.
[0177] The stent graft 1 is, therefore, held both at its proximal
and distal ends and, thereby, is both pushed and pulled when moving
from a first position (shown in FIG. 19 and described below) to a
second position (shown in FIG. 21 and described below).
Specifically, pushing is accomplished by the non-illustrated
interior end face of the hollow distal sleeve 644 (or the taper 653
of the inner sheath 652) and pulling is accomplished by the hold
that the apex capture device 634 has on the apices 32 of the bare
stent 30.
[0178] The assembly 600 according to the present invention tracks
along a guidewire 610 already inserted in the patient and extending
through the aorta and up to, but not into, the left ventricle of
the heart 720. Therefore, a guidewire 610 is inserted through the
guidewire lumen 620 starting from the nose cone assembly 630,
through the sheath assembly 650, through the handle assembly 670,
and through the apex release assembly 690. The guidewire 610
extends out the proximal-most end of the assembly 600. The
guidewire lumen 620 is coaxial with the nose cone assembly 630, the
sheath assembly 650, the handle assembly 670, and the apex release
assembly 690 and is the innermost lumen of the assembly 600
immediately surrounding the guidewire 610.
[0179] Before using the delivery system assembly 600, all air must
be purged from inside the assembly 600. Therefore, a liquid, such
as sterile U.S.P. saline, is injected through a non-illustrated
tapered luer fitting to flush the guidewire lumen at a
non-illustrated purge port located near a proximal end of the
guidewire lumen. Second, saline is also injected through the luer
fitting 612 of the lateral purge-port (see FIG. 11), which liquid
fills the entire internal co-axial space of the delivery system
assembly 600. It may be necessary to manipulate the system to
facilitate movement of the air to be purged to the highest point of
the system.
[0180] After purging all air, the system can be threaded onto the
guidewire and inserted into the patient. Because the outer catheter
660 has a predetermined length, the fixed front handle 672 can be
disposed relatively close to the entry port of the femoral artery.
It is noted, however, that the length of the outer catheter 660 is
sized such that it will not have the fixed proximal handle 672
directly contact the entry port of the femoral artery in a patient
who has the longest distance between the entry port and the
thoracic/abdominal junction 742, 732 of the aorta expected in a
patient (this distance is predetermined). Thus, the delivery
assembly 600 of the present invention can be used with typical
anatomy of the patient. Of course, the assembly 600 can be sized to
any usable length.
[0181] The nose cone assembly 630 is inserted into a patient's
femoral artery and follows the guidewire 610 until the nose cone
632 reaches the first position at a level of the celiac axis. The
first position is shown in FIG. 19. The nose cone assembly 630 is
radiopaque, whether wholly or partially, to enable the physician to
determine fluoroscopically, for example, that the nose cone
assembly 630 is in the first position. For example, the nose cone
632 can have a radiopaque marker 631 anywhere thereon or the nose
cone 632 can be entirely radiopaque.
[0182] After the nose cone assembly 630 is in the first position
shown in FIG. 19, the locking ring 676 is placed from its neutral
position N, shown in FIG. 11, into its advancement position A,
shown in FIG. 11. As will be described below, placing the locking
ring 676 into its advancement position A allows both the nose cone
assembly 630 and the internal sheath assembly 650 to move as one
when the proximal handle 678 is moved in either the proximal or
distal directions because the locking ring 676 radially locks the
graft push lumen 642 to the lumens of the apex release assembly 690
(including the guidewire lumen 620 and an apex release lumen 640).
The locking ring 676 is fixedly connected to a sheath lumen
654.
[0183] Before describing how various embodiments of the handle
assembly 670 function, a summary of the multi-lumen connectivity
relationships, throughout the neutral N, advancement A, and
deployment D positions, is described.
[0184] When the locking ring is in the neutral position N shown in
FIG. 10, the pusher clasp spring 298 shown in FIG. 48 and the
proximal spring 606 shown in FIG. 52 are both disengaged. This
allows free movement of the graft push lumen 642 with the guidewire
lumen 620 and the apex release lumen 640 within the handle body
674.
[0185] When the locking ring 676 is moved into the advancement
position A, shown in FIG. 11, the pusher clasp spring 298 shown in
FIG. 48 is engaged and the proximal spring 606 shown in FIG. 52 is
disengaged. The sheath lumen 654 (fixedly attached to the inner
sheath 652) is, thereby, locked to the graft push lumen 642
(fixedly attached to the distal sleeve 644) so that, when the
proximal handle 678 is moved toward the distal handle 672, both the
sheath lumen 654 and the graft push lumen 642 move as one. At this
point, the graft push lumen 642 is also locked to both the
guidewire lumen 620 and the apex release lumen 640 (which are
locked to one another through the apex release assembly 690 as set
forth in more detail below). Accordingly, as the proximal handle
678 is moved to the second position, shown with dashed lines in
FIG. 11, the sheath assembly 650 and the nose cone assembly 630
progress distally out of the outer catheter 660 as shown in FIGS.
20 and 21 and with dashed lines in FIG. 11.
[0186] At this point, the sheath lumen 654 needs to be withdrawn
from the stent graft 1 to, thereby, expose the stent graft 1 from
its proximal end 12 to its distal end 14 and, ultimately, entirely
off of its distal end 14. Therefore, movement of the locking ring
676 into the deployment position D will engage the proximal spring
606 shown in FIG. 52 and disengage the pusher clasp spring 298
shown in FIG. 48. At this point, the graft push lumen 642 along
with the guidewire lumen 620 and the apex release lumen 640 are
locked to the handle body 674 so as not to move with respect to the
handle body 674. The sheath lumen 654 is unlocked from the graft
push lumen 642. Movement of the distal handle 678 back to the third
position (proximally), therefore, pulls the sheath lumen 654
proximally, thus, proximally withdrawing the inner sheath 652 from
the stent graft 1.
[0187] At this point, only the bare stent 30 of the stent graft 1
is held by the delivery assembly 600. Therefore, final release of
the stent graft 1 occurs by releasing the bare stent 30 from the
nose cone assembly 630, which is accomplished using the apex
release assembly 690 as set forth below.
[0188] In order to explain how the locking and releasing of the
lumen occur as set forth above, reference is made to FIGS. 33 to
62.
[0189] FIG. 33 is a cross-sectional view of the proximal handle 678
and the locking ring 676. A pusher clasp rotator 292 is disposed
between a clasp sleeve 614 and the graft push lumen 642. A specific
embodiment of the pusher clasp rotator 292 is illustrated in FIGS.
30 through 35. Also disposed between the clasp rotator 292 and the
graft push lumen 642 is a rotator body 294, which is directly
adjacent the graft push lumen 642. A specific embodiment of the
rotator body 294 is illustrated in FIGS. 40 through 43. Disposed
between the rotator body 294 and the sheath lumen 654 is a pusher
clasp body 296, which is fixedly connected to the rotator body 294
and to the locking ring 676. A specific embodiment of the pusher
clasp body 296 is illustrated in FIGS. 44 through 46. A pusher
clasp spring 298 operatively connects the pusher clasp rotator 292
to the rotator body 294 (and, thereby, the pusher clasp body
296).
[0190] An exploded view of these components is presented in FIG.
48, where an O-ring 293 is disposed between the rotator body 294
and the pusher clasp body 296. As shown in the plan view of FIG.
47, a crimp ring 295 connects the sheath lumen 654 to the distal
projection 297 of the pusher clasp body 296. A hollow handle body
674, on which the proximal handle 678 and the locking ring 676 are
slidably mounted, holds the pusher clasp rotator 292, the rotator
body 294, the pusher clasp body 296, and the pusher clasp spring
298 therein. This entire assembly is rotationally mounted to the
distal handle 672 for rotating the stent graft 1 into position (see
FIGS. 23 and 24 and the explanations thereof below). A specific
embodiment of the handle body 674 is illustrated in FIG. 49.
[0191] A setscrew 679 extends from the proximal handle 678 to
contact a longitudinally helixed groove in the pusher clasp rotator
292 (shown in FIGS. 36 and 38). Thus, when moving the proximal
handle 678 proximally or distally, the pusher clasp rotator 292
rotates clockwise or counter-clockwise.
[0192] An alternative embodiment of the locking ring 676 is shown
in FIG. 50 et seq., which is the preferred embodiment because,
instead of applying a longitudinal movement to rotate the pusher
clasp spring 298 through the cam/follower feature of the proximal
handle 678 and pusher clasp rotator 292, a rotating locking knob
582 is located at the proximal end of the handle body 674. The knob
582 has three positions that are clearly shown in FIG. 51: a
neutral position N, an advancement position A, and a deployment
position D. The functions of these positions N, A, D correspond to
the positions N, A, D of the locking ring 676 and the proximal
handle 678 as set forth above.
[0193] In the alternative embodiment, a setscrew 584 is threaded
into the clasp sleeve 614 through a slot 675 in the handle body 674
and through a slot 583 in the knob 582 to engage the locking knob
582. Because of the x-axis orientation of the slot 583 in the knob
582 and the y-axis orientation of the slot 675 in the handle body
674, when the knob 582 is slid over the end of the handle body 674
and the setscrew 584 is screwed into the clasp sleeve 614, the knob
582 is connected fixedly to the handle body 674. When the locking
knob 582 is, thereafter, rotated between the neutral N, advancement
A, and deployment D positions, the clasp sleeve 614 rotates to
actuate the spring lock (see FIGS. 48 and 52).
[0194] A setscrew 586, shown in FIG. 53, engages a groove 605 in
the proximal clasp assembly 604 to connect the proximal clasp
assembly 604 to the clasp sleeve 614 but allows the clasp sleeve
614 to rotate around the clasp body 602. The clasp sleeve 614 is
shown in FIGS. 50 and 53 and, in particular, in FIGS. 59 to 62. The
proximal clasp assembly 604 of FIG. 53 is more clearly shown in the
exploded view of FIG. 52. The proximal clasp assembly 604 is made
of the components including a proximal spring 606, a locking washer
608, a fastener 603 (in particular, a screw fitting into internal
threads of the proximal clasp body 602), and a proximal clasp body
602. The proximal clasp body 602 is shown, in particular, in FIGS.
54 through 58. The proximal clasp assembly 604 is connected fixedly
to the handle body 674, preferably, with a screw 585 shown in FIG.
50 and hidden from view in FIG. 51 under knob 582.
[0195] The handle body 674 has a position pin 592 for engaging in
position openings at the distal end of the locking knob 582. The
position pin 592 can be a setscrew that only engages the handle
body 674. When the locking knob 582 is pulled slightly proximally,
therefore, the knob can be rotated clockwise or counter-clockwise
to place the pin 592 into the position openings corresponding to
the advancement A, neutral N, and deployment D positions.
[0196] As shown in FIG. 18, to begin deployment of the stent graft
1, the user/physician grasps both the distal handle 672 and the
proximal handle 678 and slides the proximal handle 678 towards the
distal handle 672 in the direction indicated by arrow A. This
movement, as shown in FIGS. 19 to 21, causes the flexible inner
sheath 652, holding the compressed stent graft 1 therein, to emerge
progressively from inside the outer catheter 660. Such a process
allows the stent graft 1, while constrained by the inner sheath
652, to expand to a larger diameter as shown in FIG. 12, this
diameter being substantially larger than the inner diameter of the
outer catheter 660 but smaller than the inner diameter of the
vessel in which it is to be inserted. Preferably, the outer
catheter 660 is made of a polymer (co-extrusions or teflons) and
the inner sheath 652 is made of a material, such as a fabric/woven
polymer or other similar material. Therefore, the inner sheath 652
is substantially more flexible than the outer catheter 660.
[0197] It is noted, at this point, that the inner sheath 652
contains a taper 653 at its proximal end, distal to the sheath's
652 connection to the sheath lumen 654 (at which the inner sheath
652 has a similar diameter to the distal sleeve 644 working in
conjunction with the distal sleeve 644 to capture the distal end 14
of the stent graft 1. The taper 653 provides a transition that
substantially prevents any kinking of the outer catheter 660 when
the stent graft 1 is loaded into the delivery assembly 600 (as in
the position illustrated in FIGS. 10 and 11) and, also, when the
outer catheter 660 is navigating through the femoral and iliac
vessels. One specific embodiment of the sheath lumen 654 has a
length between approximately 35 and approximately 37 inches, in
particular, 36 inches, an outer diameter of between approximately
0.20 and 0.25 inches, in particular 0.238 inches, and an inner
diameter between approximately 0.18 and approximately 0.22 inches,
in particular, 0.206 inches.
[0198] When the proximal handle 678 is moved towards its distal
position, shown by the dashed lines in FIG. 11, the nose cone
assembly 630 and the sheath assembly 650 move towards a second
position where the sheath assembly 650 is entirely out of the outer
catheter 660 as shown in FIGS. 20 and 21. As can be seen most
particularly in FIGS. 20 and 21, as the nose cone assembly 630 and
the sheath assembly 650 are emerging out of the outer catheter 660,
they are traversing the curved portion 710 of the descending aorta.
The tracking is accomplished visually by viewing radiopaque markers
on various portions of the delivery system and/or the stent graft 1
with fluoroscopic measures. Such markers will be described in
further detail below. The delivery system can be made visible, for
example, by the nose cone 630 being radiopaque or containing
radiopaque materials.
[0199] It is noted that if the harder outer catheter 660 was to
have been moved through the curved portion 710 of the aorta 700,
there is a great risk of puncturing the aorta 700, and,
particularly, a diseased portion 744 of the proximal descending
aorta 710 because the outer catheter 660 is not as flexible as the
inner sheath 652. But, because the inner sheath 652 is so flexible,
the nose cone assembly 630 and the sheath assembly 650 can be
extended easily into the curved portion 710 of the aorta 700 with
much less force on the handle than previously needed with prior art
systems while, at the same time, imparting harmless forces to the
intraluminal surface of the curved aorta 710 due to the flexibility
of the inner sheath 652.
[0200] At the second position shown in FIG. 21, the user/physician,
using fluoroscopic tracking of radiopaque markers (e.g., marker
631) on any portion of the nose cone or on the stent graft 1 and/or
sheath assemblies 630, 650, for example, makes sure that the
proximal end 112 of the stent graft 1 is in the correct
longitudinal position proximal to the diseased portion 744 of the
aorta 700. Because the entire inserted assembly 630, 650 in the
aorta 700 is still rotationally connected to the portion of the
handle assembly 670 except distal handle 672 (distal handle 672 is
connected with the outer sheath 660 and rotates independently of
the remainder of the handle assembly 670), the physician can rotate
the entire inserted assembly 630, 650 clockwise or counterclockwise
(indicated in FIG. 21 by arrow B) merely by rotating the proximal
handle 678 in the desired direction. Such a feature is extremely
advantageous because the non-rotation of the outer catheter 660
while the inner sheath 652 is rotating eliminates stress on the
femoral and iliac arteries when the rotation of the inner sheath
652 is needed and performed.
[0201] Accordingly, the stent graft 1 can be pre-aligned to place
the stent graft 1 in the correct circumferential position--defined
by placing the longitudinal support member 40 substantially at the
superior longitudinal surface line of the curved aorta (with
respect to anatomical position). FIG. 23 illustrates the
longitudinal support member 40 not in the correct superior position
and FIG. 24 illustrates the longitudinal support member 40 in the
correct superior position. The optimal superior surface position
is, preferably, near the longest superior longitudinal line along
the circumference of the curved portion of the aorta as shown in
FIGS. 23 and 24. As set forth above, when the longitudinal support
member 40 extends along the superior longitudinal line of the
curved aorta, the longitudinal support member 40 substantially
eliminates any possibility of forming a kink in the inferior radial
curve of the stent graft 1 during use and also allows transmission
of longitudinal forces exerted along the inside lumen of the stent
graft 1 to the entire longitudinal extent of the stent graft 1,
thereby allowing the entire outer surface of the stent graft 1 to
resist longitudinal migration.
[0202] In prior art stent grafts and stent graft delivery systems,
the stent graft is, typically, provided with symmetrically-shaped
radiopaque markers along one longitudinal line and at least one
other symmetrically-shaped radiopaque marker disposed along another
longitudinal line on the opposite side (180 degrees) of the stent
graft. Thus, using two-dimensional fluoroscopic techniques, the
only way to determine if the stent graft is in the correct
rotational position is by having the user/physician rotate the
stent graft in both directions until it is determined that the
first longitudinal line is superior and the other longitudinal line
is anterior. This required more work by the physician and is,
therefore, undesirable.
[0203] According to a preferred embodiment of the invention
illustrated in FIGS. 27 and 28, unique radiopaque markers 232, 234
are positioned on the stent graft 1 to assist the user/physician in
correctly positioning the longitudinal support member 40 in the
correct aortic superior surface position with only one directional
rotation that is also the minimal rotation needed to place the
stent graft 1 in the rotationally correct position.
[0204] Specifically, the stent graft 1 is provided with a pair of
symmetrically shaped but diametrically opposed markers 232, 234
indicating to the user/physician which direction the stent graft 1
needs to be rotated to align the longitudinal support member 40 to
the superior longitudinal line of the curved aorta (with respect to
anatomical position). Preferably, the markers 232, 234 are placed
at the proximate end 12 of the graft sleeve 10 on opposite sides
(180 degrees) of the graft sleeve 10.
[0205] The angular position of the markers 232, 234 on the graft
sleeve 10 is determined by the position of the longitudinal support
member 40. In a preferred embodiment, the support member 40 is
between the two markers 232, 234. To explain such a position, if
the marker 232 is at a 0 degree position on the graft sleeve 10 and
the marker 234 is at a 180 degree position, then the centerline 45
of the support member 40 is at a 90 degree position. However, an
alternative position of the markers can place the marker 234 90
degrees away from the first degree 41 (see FIG. 1). Such a
positioning is dependent somewhat upon the way in which the
implantation is to be viewed by the user/physician and can be
varied based on other factors. Thus, the position can be rotated in
any beneficial way.
[0206] Preferred ancillary equipment in endovascular placement of
the stent graft 1 is a fluoroscope with a high-resolution image
intensifier mounted on a freely angled C-arm. The C-arm can be
portable, ceiling, or pedestal mounted. It is important that the
C-arm have a complete range of motion to achieve AP to lateral
projections without moving the patient or contaminating the sterile
field. Capabilities of the C-arm should include: Digital
Subtraction Angiography, High-resolution Angiography, and
Roadmapping.
[0207] For introduction of the delivery system into the groin
access arteries, the patient is, first, placed in a sterile field
in a supine position. To determine the exact target area for
placement of the stent graft 1, the C-arm is rotated to project the
patient image into a left anterior oblique projection, which opens
the radial curve of the thoracic aortic arch for optimal
visualization without superimposition of structures. The degree of
patient rotation will vary, but is usually 40 to 50 degrees. At
this point, the C-arm is placed over the patient with the central
ray of the fluoroscopic beam exactly perpendicular to the target
area. Such placement allows for the markers 232, 234 to be
positioned for correct placement of the stent graft 1. Failure to
have the central ray of the fluoroscopic beam perpendicular to the
target area can result in parallax, leading to visual distortion to
the patient anatomy due to the divergence of the fluoroscopic x-ray
beam, with a resultant misplacement of the stent graft 1. An
angiogram is performed and the proposed stent graft landing zones
are marked on the visual monitor. Once marked, neither the patient,
the patient table, nor the fluoroscopic C-arm can be moved,
otherwise, the reference markers become invalid. The stent graft 1
is, then, placed at the marked landing zones.
[0208] In a preferred embodiment, the markers 232, 234 are
hemispherical, in other words, they have the approximate shape of a
"D". This shape is chosen because it provides special, easy-to-read
indicators that instantly direct the user/physician to the correct
placement position for the longitudinal support member 40. FIG. 27,
for example, illustrates a plan view of the markers 232, 234 when
they are placed in the upper-most superior longitudinal line of the
curved aorta. The correct position is indicated clearly because the
two hemispheres have the flat diameters aligned on top of or
immediately adjacent to one another such that a substantially
complete circle is formed by the two hemispherically rounded
portions of the markers 232, 234. This position is also indicated
in the perspective view of FIG. 28.
[0209] Each of FIGS. 27 and 28 have been provided with examples
where the markers 232, 234 are not aligned and, therefore, the
stent graft 1 is not in the correct insertion position. For
example, in FIG. 27, two markers 232', 234' indicate a misaligned
counter-clockwise-rotated stent graft 1 when viewed from the plane
236 at the right end of the stent graft 1 of FIG. 23 looking toward
the left end thereof and down the axis 11. Thus, to align the
markers 232', 234' in the most efficient way possible (the shortest
rotation), the user/physician sees that the distance between the
two flat diameters is closer than the distance between the highest
points of the hemispherical curves. Therefore, it is known that the
two flat diameters must be joined together by rotating the stent
graft 1 clockwise.
[0210] FIG. 28 has also been provided with two markers 232'', 234''
indicating a misaligned clockwise-rotated stent graft 1 when viewed
from the plane 236 at the right end of the stent graft 1 of FIG. 27
looking toward the left end thereof and down the axis 11. Thus, to
align the markers 232'', 234'' in the most efficient way possible
(the shortest rotation), the user/physician sees that the distance
between the highest points of the hemispherical curves is smaller
than the distance between the two flat diameters. Therefore, it is
known that the two flat diameters must be joined together by
rotating the stent graft 1 in the direction that the highest points
of the hemispherical curves point; in other words, the stent graft
1 must be rotated counter-clockwise.
[0211] A significant advantage provided by the diametrically
opposed symmetric markers 232, 234 is that they can be used for
migration diagnosis throughout the remaining life of a patient
after the stent graft 1 has been placed inside the patient's body.
If fluoroscopic or radiographic techniques are used any time after
the stent graft 1 is inserted in the patient's body, and if the
stent graft 1 is viewed from the same angle as it was viewed when
placed therein, then the markers' 232, 234 relative positions
observed should give the examining individual a very clear and
instantaneous determination as to whether or not the stent graft 1
has migrated in a rotational manner.
[0212] The hemispherical shape of the markers 232, 234 are only
provided as an example shape. The markers 232, 234 can be any shape
that allows a user/physician to distinguish alignment and direction
of rotation for alignment. For example, the markers 232, 234 can be
triangular, in particular, an isosceles triangle having the single
side be visibly longer or shorter than the two equal sides.
[0213] When the stent graft 1 is in place both longitudinally and
circumferentially (FIG. 21), the stent graft 1 is ready to be
removed from the inner sheath 652 and implanted in the vessel 700.
Because relative movement of the stent graft 1 with respect to the
vessel is no longer desired, the inner sheath 652 needs to be
retracted while the stent graft 1 remains in place, i.e., no
longitudinal or circumferential movement. Such immovability of the
stent graft 1 is insured by, first, the apex capture device 634 of
the nose cone assembly 630 holding the front of the stent graft 1
by its bare stent 30 (see FIGS. 13, 22, and 23) and, second, by
unlocking the locking ring 676/placing the locking ring/knob in the
D position--which allows the sheath lumen 654 to move independently
from the guidewire lumen 620, apex release lumen 640, and graft
push lumen 642. The apex capture device 634, as shown in FIGS. 13,
14, 30 and 311 (and as will be described in more detail below), is
holding each individual distal apex 32 of the bare stent 30 in a
secure manner--both rotationally and longitudinally.
[0214] The nose cone assembly 630, along with the apex capture
device 634, is securely attached to the guidewire lumen 620 (and
the apex release lumen 640 at least until apex release occurs). The
inner sheath 652 is securely attached to a sheath lumen 654, which
is coaxially disposed around the guidewire lumen 620 and fixedly
attached to the proximal handle 678. The stent graft 1 is also
supported at its distal end by the graft push lumen 642 and the
distal sleeve 644 or the taper 653 of the inner sheath 652. (The
entire coaxial relationship of the various lumen 610, 620, 640,
642, 654, and 660 is illustrated for exemplary purposes only in
FIG. 25, and a portion of which can also be seen in the exploded
view of the handle assembly in FIG. 50) Therefore, when the
proximal handle 678 is moved proximally with the locking ring 676
in the deployment position D, the sheath lumen 654 moves proximally
as shown in FIGS. 13, 22, and 23, taking the sheath 652 proximally
along with it while the guidewire lumen 620, the apex release lumen
640, the graft push lumen 642, and the distal sleeve 644 remain
substantially motionless and, therefore, the stent graft 1 remains
both rotationally and longitudinally steady.
[0215] The stent graft 1 is, now, ready to be finally affixed to
the aorta 700. To perform the implantation, the bare stent 30 must
be released from the apex capture device 634. As will be described
in more detail below, the apex capture device 634 shown in FIGS.
13, 14, and 29 to 32, holds the proximal apices 32 of the bare
stent 30 between the distal apex head 636 and the proximal apex
body 638. The distal apex head 636 is fixedly connected to the
guidewire lumen 620. The proximal apex body 638, however, is
fixedly connected to the apex release lumen 640, which is coaxial
with both the guidewire lumen 620 and the sheath lumen 654 and
disposed therebetween, as illustrated diagrammatically in FIG. 25.
(As will be described in more detail below, the graft push lumen
642 is also fixedly connected to the apex release lumen 640.)
Therefore, relative movement of the apex release lumen 640 and the
guidewire lumen 620 separates the distal apex head 636 and a
proximal apex body 638 from one another.
[0216] To cause such relative movement, the apex release assembly
690 has, in a preferred embodiment, three parts, a distal release
part 692, a proximal release part 694, and an intermediate part 696
(which is shown in the form of a clip in FIGS. 16 and 26). To
insure that the distal apex head 636 and the proximal apex body 638
always remain fixed with respect to one another until the bare
stent 30 is ready to be released, the proximal release part 694 is
formed with a distal surface 695, the distal release part 692 is
formed with a proximal surface 693, and the intermediate part 696
has proximal and distal surfaces corresponding to the surfaces 695,
693 such that, when the intermediate part 696 is inserted removably
between the distal surface 695 and the proximal surface 693, the
intermediate part 696 fastens the distal release part 692 and the
proximal release part 694 with respect to one another in a
form-locking connection. A form-locking connection is one that
connects two elements together due to the shape of the elements
themselves, as opposed to a force-locking connection, which locks
the elements together by force external to the elements.
Specifically, as shown in FIG. 26, the clip 696 surrounds a distal
plunger 699 of the proximal release part 694 that is inserted
slidably within a hollow 698 of the distal release part 692. The
plunger 699 of the proximal release part 694 can slide within the
hollow 698, but a stop 697 inside the hollow 698 prevents the
distal plunger 699 from withdrawing from the hollow 698 more than
the longitudinal span of the clip 696.
[0217] To allow relative movement between the distal apex head 636
and the proximal apex body 638, the intermediate part 696 is
removed easily with one hand and, as shown from the position in
FIG. 16 to the position in FIG. 17, the distal release part 692 and
the proximal release part 694 are moved axially towards one another
(preferably, the former is moved towards the latter). Such movement
separates the distal apex head 636 and the proximal apex body 638
as shown in FIG. 14. Accordingly, the distal apices 32 of the bare
stent 30 are free to expand to their natural position in which the
bare stent 30 is released against the vessel 700.
[0218] Of course, the apex release assembly 690 can be formed with
any kind of connector that moves the apex release lumen 640 and the
guidewire lumen 620 relative to one another. In a preferred
alternative embodiment, for example, the intermediate part 696 can
be a selectable lever that is fixedly connected to either one of
the distal release part 692 or the proximal release part 694 and
has a length equal to the width of the clip 696 shown in FIG. 26.
Thus, when engaged by pivoting the lever between the distal release
part 692 and the proximal release part 694, for example, the parts
692, 694 cannot move with respect to one another and, when
disengaged by pivoting the lever out from between the parts 692,
694, the distal release part 692 and the proximal release part 694
are free to move towards one another.
[0219] The apex clasp device is unique to the present invention in
that it incorporates features that allow the longitudinal forces
subjected on the stent graft 1 to be fully supported, through the
bare stent 30, by both the guidewire lumen 620 and apex release
lumen 640. Support occurs by providing the distal apex head 636
with a distal surface 639 supporting the proximal apices 32 of the
bare stent 30, which is particularly shown in the enlarged
perspective view of the distal apex head 636 provided in FIG. 29.
The distal surface 639, in turn, rests on the proximal apex body
638 when in the closed position, as more clearly shown in FIGS. 30
and 31. Thus, the longitudinal forces are fully transmitted to both
the guidewire lumen 620 and apex release lumen 640, making the
assembly much stronger.
[0220] Having the distal surface 639 be the load-bearing surface of
the proximal apices 32 ensures expansion of the each one of the
distal apices 32 from the apex release assembly 690. The proximal
surface 641 of the distal apex head 636 meets with the interior
surfaces of the proximal apex body 638 to help carry the apex load
because the apices of the bare stent 30 are captured therebetween
when the apex capture device 634 is closed. Such capture can be
clearly seen in the cut-away view of the proximal apex body 638 in
FIG. 31. For release of the apices 32 of the bare stent 30, the
proximal apex body 638 moves to the left (with respect to FIG. 32).
Because of friction occurring between the apices 32 and the "teeth"
of the proximal apex body 638 when the apices 32 are captured, the
apices 32 will also try to move to the left along with the proximal
apex body 638 and, if allowed to do so, possibly would never clear
the "teeth" to allow each apex 32 to expand. However, as the
proximal apex body 638 disengages (moves in the direction of arrow
C in FIG. 31), direct contact with the distal surface 639 entirely
prevents the apices 32 from sliding in the direction of arrow C
along with the proximal apex body 638 to ensure automatic release
of every captured apex 32 of the bare stent 30. Because the
proximal apex body 638 continues to move to the left, eventually
the "teeth" will clear their respective capture of the apices 32
and the bare stent 30 will, therefore, expand entirely. The release
position of the distal apex head 636 and the proximal apex body 638
is shown in FIG. 32, and corresponds to the position of the apex
release assembly 690 in FIG. 17. As can be seen, tapers on the
distal outer surfaces of the proximal apex body 638 further assist
in the prevention of catching the proximal apices 32 of the bare
stent 30 on any part of the apex capture device 634.
[0221] Simply put, the apex capture device 634 provides support for
load placed on the stent graft 1 during advancement A of the inner
sheath 652 and during withdrawal of the inner sheath 652 (i.e.,
during deployment D). Such a configuration benefits the apposition
of the bare stent 30 by releasing the bare stent 30 after the
entire graft sleeve 10 has been deployed, thus reducing the
potential for vessel perforation at the point of initial
deployment.
[0222] When the stent graft 1 is entirely free from the inner
sheath 652 as shown in FIG. 23, the proximal handle 678 is, then,
substantially at or near the third position (deployment position)
shown in FIG. 10.
[0223] The stent graft 1 is, now, securely placed within the vessel
and the entire portion 630, 650, 660 of the assembly 600 may be
removed from the patient.
[0224] While the preferred embodiments of the invention have been
illustrated and described, it will be clear that the invention is
not so limited. Numerous modifications, changes, variations,
substitutions, and equivalents will occur to those skilled in the
art without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *