U.S. patent application number 10/176834 was filed with the patent office on 2003-12-25 for implantable prosthesis.
Invention is credited to DiMatteo, Kristian, Spiridigliozzi, John, Thistle, Robert.
Application Number | 20030236565 10/176834 |
Document ID | / |
Family ID | 29734231 |
Filed Date | 2003-12-25 |
United States Patent
Application |
20030236565 |
Kind Code |
A1 |
DiMatteo, Kristian ; et
al. |
December 25, 2003 |
Implantable prosthesis
Abstract
A graft system for intraluminal delivery in a vessel in need of
repair comprising a graft, anchoring means, and a strippable sheath
around at least part of the graft. A preferred anchoring means is a
balloon-expandable stent. Also included in the invention is a
method of using the device to treat a body lumen. The strippable
sheath is removable by pulling on a drawstring to remove it which
permits expansion of the graft. The positioning of the device may
then be adjusted prior to stent dilation. A preferred embodiment of
the invention includes a bifurcated graft system for intraluminal
delivery in an aortic aneurysm comprising a bifurcated graft having
a distal region and two legs, an expandable stent disposed in part
of the distal region, and a strippable crocheted sheath around the
distal region and one of the two legs. The strippable crocheted
sheath is removable by untying it to permit expansion of the graft
after initial placement within the aneurysm.
Inventors: |
DiMatteo, Kristian;
(Waltham, MA) ; Thistle, Robert; (Brockton,
MA) ; Spiridigliozzi, John; (Sharon, MA) |
Correspondence
Address: |
Paul F. Prestia
RatnerPrestia
One Westlakes (Berwyn), Suite 301
P.O. Box 980
Valley Forge
PA
17482
US
|
Family ID: |
29734231 |
Appl. No.: |
10/176834 |
Filed: |
June 21, 2002 |
Current U.S.
Class: |
623/1.12 |
Current CPC
Class: |
A61F 2002/9583 20130101;
A61F 2/89 20130101; A61F 2/954 20130101; A61F 2/07 20130101; A61F
2/958 20130101; A61F 2002/075 20130101; A61F 2002/9511 20130101;
Y10S 623/903 20130101; A61F 2/88 20130101; A61F 2002/065
20130101 |
Class at
Publication: |
623/1.12 |
International
Class: |
A61F 002/06 |
Claims
What is claimed:
1. A system for endoluminal delivery and emplacement of a
prosthesis in a body lumen, comprising: a tubular graft having a
central axis, a first radially compressed configuration for
endoluminal delivery, and a second radially expanded configuration;
radial expansion means for expanding the graft to its radially
expanded configuration; and a strippable sheath surrounding at
least part of the graft in the first configuration thereof, the
strippable sheath being removable to permit expansion of the
graft.
2. The system of claim 1 further comprising anchoring means for
anchoring said tubular graft in said body lumen.
3. The system of claim 1 further comprising a drawstring extending
from the strippable sheath, wherein retraction of the drawstring
results in the removal of said sheath.
4. The system of claim 3 wherein said strippable sheath is
crocheted and retraction of said drawstring results in the untying
and removal of said sheath.
5. The system of claim 1 wherein the graft includes a
bifurcation.
6. The system of claim 5 wherein said graft includes an
unbifurcated tubular distal section on one side thereof and two
tubular distal sections on the other side thereof.
7. The system of claim 6 wherein the strippable sheath extends
around the unbifurcated distal section and only one of the
bifurcated distal sections of the graft.
8. The system of claim 6 wherein the strippable sheath extends
around only the unbifurcated distal section.
9. The system of claim 1 wherein the radial expansion means is an
inflatable balloon.
10. The system of claim 2 wherein the anchoring means is a
stent.
11. The system of claim 10 wherein the stent is disposed at only
one end of the graft.
12. The system of claim 1 for use in repairing an aortic aneurysm,
wherein: the graft is a bifurcated graft having a distal aortic
region and two distal iliac legs; a balloon expandable stent is
disposed in the distal aortic region; and the strippable sheath is
a crocheted strippable sheath which extends around the distal
region and only one of the two distal legs.
13. A system for endoluminal delivery and emplacement of a
prosthesis in a body lumen, comprising: a tubular graft; a tubular
stent disposed in at least part of the graft, the stent and graft
having a common central axis, a first radially compressed
configuration for endoluminal delivery and a second radially
expanded configuration; radial expansion means for expanding the
stent and graft to the radially expanded configurations thereof; a
strippable sheath surrounding at least part of the graft in the
first configuration thereof, the strippable crocheted sheath being
removable to permit expansion of the graft and stent; and a
drawstring extending from the strippable sheath, wherein retraction
of the drawstring results in the untying of said sheath.
14. The system of claim 13 further comprising anchoring means for
anchoring said tubular graft in said body lumen.
15. The system of claim 13 wherein said strippable sheath is
crocheted and retraction of said drawstring results in the untying
and removal of said sheath.
16. The system of claim 13 wherein the graft includes a
bifurcation.
17. The system of claim 16 wherein said graft includes an
unbifurcated tubular distal section on one side thereof and two
tubular distal sections on the other side thereof.
18. The system of claim 17 wherein the strippable sheath extends
around the unbifurcated distal section and only one of the
bifurcated distal sections of the graft.
19. The system of claim 17 wherein the strippable sheath extends
around only the unbifurcated distal section.
20. The system of claim 13 wherein the radial expansion means is an
inflatable balloon.
21. The system of claim 14 wherein the anchoring means is a
stent.
22. The system of claim 21 wherein the stent is disposed at only
one end of the graft.
23. The system of claim 13 for use in repairing an aortic aneurysm,
wherein: the graft is a bifurcated graft having a distal aortic
region and two distal iliac legs; a balloon expandable stent is
disposed in the distal aortic region; and the strippable sheath is
a crocheted strippable sheath which extends around the distal
region and only one of the two distal legs.
24. A bifurcated graft system for intraluminal delivery in an
aortic aneurysm in need of repair comprising: a bifurcated graft
having a distal region and two legs; an expandable stent disposed
in part of said distal region; a strippable sheath around said
distal region and one of said two legs, the strippable sheath being
removable to permit expansion of the graft and stent; and a
drawstring extending from said strippable crocheted sheath, wherein
retraction of said drawstring results in the removal of said
sheath.
25. An aortic graft system for intraluminal delivery to repair an
abdominal aortic aneurysm in an aorta having two iliac arteries
associated therewith at an aortic bifurcation, comprising: a graft
having a first end and an intermediate region disposed adjacent
said first end, the graft being self expandable from a reduced
profile for insertion into the aorta to an expanded profile; means
for securing the first end of the graft to the aorta, the securing
means having a first diameter which permits intraluminal delivery
of the securing means into the aorta and the securing means having
a second, expanded diameter, to secure the first end of the graft
to the aorta; radial expansion means for expanding securing means
and graft to the radially expanded configurations thereof; a
strippable sheath covering at least part of said graft, the
strippable sheath maintaining the graft in the reduced profile; and
at least one drawstring extending from the strippable sheath, the
drawstring being retractable to permit removal of the strippable
sheath and subsequent expansion of the graft from its reduced
profile to its expanded profile.
26. The graft system of claim 25 wherein said securing means
includes a balloon expandable stent.
27. A method of inserting a graft system to repair a vessel in need
of repair comprising the steps of: inserting a catheter from a
vessel access location into a vessel to a deployment location in
need of repair, the catheter having a graft system disposed
thereon, the graft system comprising: a centrally disposed push
wire surrounded by a graft; anchoring means for anchoring said
tubular graft in said vessel; a strippable sheath around at least
part of the graft, the strippable sheath being removable to permit
expansion of the graft; and a drawstring extending from the
strippable sheath to the access location, wherein retraction of the
drawstring results in the removal of the sheath; retracting the
drawstring to cause removal of the strippable sheath to allow
expansion of the graft; anchoring the graft within the vessel; and
removing the catheter.
28. The method of claim 27 wherein the anchoring means comprises a
balloon expandable stent and said anchoring step comprises
inflating a balloon disposed on the catheter to expand said balloon
expandable stent.
29. The method of claim 27 wherein the strippable sheath is a
crocheted sheath.
30. The method of claim 27 wherein the vessel in need of repair is
a bifurcated vessel, the graft is bifurcated having a distal region
and two distal legs, and the strippable sheath extends around the
distal region and only one of the two distal legs.
31. The method of claim 30 wherein said vessel in need of repair is
an aortic aneurysm.
32. The method of claim 27 wherein said inserting step is through
one iliac artery, further comprising the step of: before said
retracting step, pulling the leg not covered by the strippable
crocheted sheath into the iliac artery not used to insert the
catheter.
33. A method of inserting a graft system to repair a vessel in need
of repair comprising the steps of: inserting a catheter from a
vessel access location into a vessel to a deployment location in
need of repair, the catheter having a graft system disposed
thereon, the graft system comprising: a centrally disposed push
wire surrounded by a graft; an expandable stent disposed in at
least part of the graft; a strippable crocheted sheath around at
least part of the graft, the strippable crocheted sheath being
removable to permit expansion of the graft and stent; and a
drawstring extending from the strippable crocheted sheath to the
access location, wherein retraction of the drawstring results in
the untying and removal of the sheath; retracting the drawstring to
cause untying and removal of the strippable crocheted sheath to
allow expansion of the graft; expanding the stent to anchor the
stent and the graft within the vessel; and removing the
catheter.
34. The method of claim 33 wherein the stent is a balloon
expandable stent and said expanding step comprises inflating a
balloon disposed on said catheter.
35. The method of claim 33 wherein the vessel in need of repair is
an aortic aneurysm, the graft is bifurcated having a distal region
and two distal legs, and the strippable crocheted sheath extends
around the distal region and only one of the two distal legs.
36. The method of claim 35 wherein said inserting step is through
one iliac artery, further comprising the step of: before said
retracting step, pulling the leg not covered by the strippable
crocheted sheath into the iliac artery not used to insert the
catheter.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to endoluminally
implantable luminal prostheses, and more specifically to such
prostheses which are implantable into a body lumen, particularly a
blood vessel, without using a solid outer sheath during
placement.
BACKGROUND OF THE INVENTION
[0002] Prostheses which are used to restore dilation or repair
otherwise damaged body lumens (such as blood vessels) are known.
Typically these prostheses comprise a tubular graft comprised of
woven or molded polymeric material, optionally supported in whole
or in part by an interiorly or exteriorly disposed mechanical
support structure usually referred to as a stent. Prostheses used
for this purpose may be introduced percutaneously at an access
location remote from a location in a body lumen where the
prosthesis is needed but in endoluminal communication therewith.
For this purpose, the prosthesis is compressed and held in the
compressed state until it has been moved endoluminally to the site
in need of repair, where it is expanded and secured. Expansion may
be effected, either mechanically by means such as a balloon
catheter, or automatically under an elastic or phase change
force.
[0003] Typically, the prosthesis is retained, in its first
configuration, in an outer sleeve or sheath, which may be retained
in, or may actually be the forward end of, a delivery catheter.
Such a delivery catheter is introduced at the access location and
maneuvered through the luminal system to the site where the
prosthesis is needed. When the prosthesis reaches that location, it
must either be ejected from the delivery catheter, or held in
place, while the delivery and/or any surrounding sleeve is
retracted.
[0004] Another method comprises compressing the prosthesis to a
reduced cross-section and then pushing it, in the compressed state,
into a catheter which has been previously inserted into the
patient. A pusher is used to push the compressed endoprosthesis
through the catheter and out the distal end where it expands into
place. One drawback of this method is that considerable force must
be exerted on the device as it is pushed through the catheter to
overcome frictional forces along the lumen. In each of these cases,
the cross section of the prosthesis and surrounding catheter, by
which it is transported to the deployment location, is a factor
which contributes to difficulties in use and deployment of such
systems.
[0005] In one particular application of such prostheses, an
abdominal aortic aneurysm is treated. Such an aneurysm usually
occurs in the infrarenal portion of an arterioscleroticly diseased
aorta, between the renal arteries and the two iliac arteries,
sometimes extending across the aortic bifurcation into one or both
iliacs. Typical prostheses for the repair of this region include
bifurcated tubular grafts or stent grafts having an aortic section,
(typically a section of the prosthesis adapted to be disposed
within the aneurysm) and two iliac sections which extend from the
aortic section into the iliac arteries. Methods are known which
include inserting a bifurcated graft prosthesis endoluminally
through one iliac artery and securing it to the aorta by expansion
of a stent which is a part of the prosthesis.
[0006] It is also known to compress a self-expanding tubular
stent-graft and restrain it against a self-expansion force in its
reduced cross section configuration, relative to its expanded
state, by a knitted strippable sheath. After the sheathed
prosthesis is inserted into place within the body, a filament of
the sheath is pulled distally to de-knit the sheath and permit its
removal as a single filament strand from the prosthesis, allowing
the prosthesis to expand to a cross section corresponding to its
in-use position. Known sheaths include meshworks of crocheted
material extending over the entire length of the prosthesis. One
drawback of such an arrangement, however, is that once the
drawstring is pulled, expansion of the supporting stent prevents
further adjustments of the position of the prosthesis relative to
the surrounding lumen.
SUMMARY OF THE INVENTION
[0007] The present invention includes a graft system for
intraluminal delivery in a body lumen in need of repair. The system
comprises a graft, a means for radially expanding the graft and a
means for securing at least one end of the graft to the lumen in
need of repair (those means optionally comprising a balloon
expandable barbed stent disposed in at least part of the graft),
and a strippable sheath around at least part of the graft. The
strippable sheath, which obviates the need for a hard outer sheath
to restrain the prosthesis in its compressed configuration, is
removable. Depending upon the type of strippable sheath used, it
may be removable by pulling a drawstring to untie or unknit it. In
one embodiment, where a scored plastic sheath is used, the scored
plastic is unwrapped by initiating the tearing of the scoring of
the sheath. A preferred embodiment uses a tied crocheted sheath
which is removed by pulling on a drawstring which unties the entire
sheath to permit expansion of the graft.
[0008] A preferred embodiment of the invention includes a
bifurcated graft system for endoluminal delivery in an aortic
aneurysm comprising a bifurcated graft having an aortic section and
two iliac legs, an expandable stent disposed near the end of the
aortic section, and a strippable crocheted sheath around the aortic
section and one of the two legs. The strippable crocheted sheath is
removable by untying it to permit expansion of the graft after
initial placement within the aneurysm.
[0009] Also included in the present invention is a method of
inserting a graft system to repair a vessel in need of repair
comprising the steps of inserting a catheter into an access
location of a body lumen to a location in need of repair, the
catheter including the graft system of the present invention at the
forward end of an axially disposed push rod, with no hard sheath
exterior of the graft itself. Once transported to the deployment
location, the drawstring (in the preferred embodiment) is retracted
to cause untying of a strippable crocheted sheath to allow
expansion of the graft. The graft is then positioned, by
positioning means such as radiopaque markers and an imaging system,
and the graft is then dilated, by, for example, a balloon
expandable stent with barbs at the end thereof. In this way, the
graft is anchored within the vessel. The catheter is then
removed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The features of the invention believed to be novel and the
elements characteristic of the invention are set forth with
particularity in the appended claims. The figures are for
illustration purposes only and are not drawn to scale. The
invention itself, however, both as to organization and method of
operation, may best be understood by reference to the detailed
description which follows taken in conjunction with the
accompanying drawings in which:
[0011] FIG. 1 is a cross section of the proximate end of a device
according to the present invention showing, among other things, the
compressed graft held in place by a strippable crocheted
sheath;
[0012] FIG. 2 is the same as the device of FIG. 1 except without
the strippable crocheted sheath;
[0013] FIG. 3 is shows the device of claim 2 during the initial
stage of stent dilation through balloon inflation;
[0014] FIG. 4 shows the balloon fully inflated and the stent fully
dilated;
[0015] FIG. 5 shows the balloon deflated and the deployment device
about to be removed;
[0016] FIG. 6 shows an early step in device placement where the
strippable crocheted sheath is disposed around part of the graft,
holding it against its relaxed state;
[0017] FIG. 7 shows a subsequent step where a contralateral limb is
pulled into an adjacent iliac artery;
[0018] FIG. 8A shows the device in place just prior to removal of a
strippable crocheted sheath which covers the distal trunk portion
and one iliac leg;
[0019] FIG. 8B shows the device in place just prior to removal of a
strippable crocheted sheath which covers the distal trunk portion
and both iliac legs;
[0020] FIG. 8C shows the device in place just prior to removal of a
strippable crocheted sheath which covers only the distal trunk
portion;
[0021] FIG. 9 shows the removal of the strippable crocheted sheath
where the drawstring was pulled to untie the sheath;
[0022] FIG. 10 shows the device with the strippable crocheted
sheath removed just prior to dilation of the stent;
[0023] FIG. 11 shows the stent dilation under force of a
balloon;
[0024] FIG. 12 shows the device in place after stent dilation and
catheter removal; and
[0025] FIG. 13 shows the iliac distal ends secured within the iliac
arteries.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The present invention includes a graft system and method for
its use to repair a diseased or otherwise defective body lumen. A
preferred embodiment of the present invention includes a graft
system for intraluminal delivery in a vessel in need of repair
comprising a graft, a radial expansion means to expand the graft to
its fully dilated configuration (preferably a balloon expandable
stent disposed within at least part of the graft), and a strippable
crocheted sheath around at least part of the graft. The strippable
crocheted sheath is removable to permit expansion of the graft and
stent. Included as a part of the invention is a bifurcated graft
system for intraluminal delivery in an aortic aneurysm in need of
repair comprising a bifurcated graft having a distal region and two
legs, a balloon expandable stent disposed in part of the distal
region, and a strippable crocheted sheath around the distal region
and one of the two legs. The strippable crocheted sheath is
removable (by unraveling or untying) to permit expansion of the
graft and stent after initial placement within the aneurysm.
[0027] Different embodiments include different means for securing
the first end of the graft to the aorta. Generally, the securing
means has a first diameter which permits intraluminal delivery of
the securing means into the aorta and a second, expanded diameter,
to secure the first end of the graft to the aorta. A preferred
securing means is a balloon-expandable stent. The stent used in the
device of the present invention is not completely self-expandable,
but may be either completely balloon-expandable or partially
self-expandable and partially manually expandable (such as with a
balloon). The stent is fully deployed using a radial expansion
means for expanding the stent and graft to a radially expanded
configuration.
[0028] A radial expansion means is necessary because the present
invention does not fully expand automatically upon removal of the
sheath. This allows the position of the device to be adjusted prior
to fully dilating the stent, but after removal of the delivery
sheath. Other options for the expansion means include using a stent
made from a material which is self-expandable at temperatures
higher than body temperature. Such materials can be used where heat
is added at the site of deployment when dilation is desired to warm
the device to a temperature in excess of body temperature such that
self-expansion will occur after the sheath has been removed. Such a
heat-activated expansion contemplates the application of heat after
the sheath is removed for a controlled expansion after placement.
In such a case, the material would be used with the present
invention without a balloon expansion device, or in combination
with a balloon (e.g. where the initial expansion, prior to heat
application, is through the use of a balloon). An important part of
the present invention is that the stent and related parts of the
device not automatically expand completely after the strippable
sheath is removed.
[0029] In a preferred embodiment, the delivery sheath is a
strippable sheath that covers at least part of the graft, the
strippable sheath maintaining the graft in the reduced profile
prior to, and during, insertion into the passageway in need of
repair. A preferred strippable sheath is a crocheted strippable
sheath with a drawstring extending from the strippable sheath. Upon
pulling the drawstring at the lumen access location, the crocheted
sheath is untied, or removed, permitting expansion of the graft and
related device component(s), first by relaxation and then by a
radial expansion means such as a balloon expander acting directly
on the graft or balloon expandable stent. In another embodiment,
the strippable sheath is a scored plastic sheath which is removed
by tearing of the scoring of the sheath and pulling the torn
plastic sheath out of the body lumen from the point of insertion.
Other embodiments would include a quickly biodegradable sheath,
such as a polyvinylalcohol (PVA) sheath, although this embodiment
must be carefully used as precise control over the timing of sheath
removal can introduce a variable into the system deployment
procedure.
[0030] It is noted that in this specification, "proximal" shall
mean closest to point of insertion, and "distal" shall mean
furthest from the point of insertion.
[0031] FIG. 1 shows the distal end of a device in accordance with
the present invention. Guidewire lumen 100 (for a guidewire which
is not shown) is accompanied by balloon dilation lumen 110 for
inflating balloon 120. Disposed around balloon 120 is stent 130,
which is shown in its compressed state. Graft 140 is disposed atop
stent 130 and is shown as held in its compressed state by
strippable crocheted sheath 150. Materials which are suitable for
the graft are well known to those skilled in the art and include
for example woven polyester and molded expanded
polytetrafluoroethylene.
[0032] Soft elastic tube 160 is also shown disposed between
catheter tip 170 and graft 140. Soft elastic tube 160 combines with
rounded catheter tip 170 to provide a relatively smooth, easily
insertable end to the overall device. Soft elastic tube 160 is
typically made of silicone. Thus, as the catheter and its
components are threaded through the body lumen along a guidewire,
damage to the lumen is minimized.
[0033] FIG. 2 shows the same view as FIG. 1 but with strippable
crocheted sheath 150 removed. In this figure, it can be seen that
graft 140 has been allowed to expand to a relaxed configuration.
This relaxed configuration is one which graft 140 would have had
but for the restraint applied to it by strippable crocheted sheath
150. Had the device been inserted into the body lumen without
strippable crocheted sheath 150 in place over graft 140, insertion
would have been much more traumatic for the patient. Without
strippable crocheted sheath 150, graft 140 would be allowed to
expand and would create a looser, larger, and more cumbersome
profile, reducing the ease with which the overall device can be
inserted. Included among the problems that would result without use
of strippable crocheted sheath 150 would be kinking and twisting of
graft 140 as the catheter is advanced through the relatively
tortuous passageway leading to the desired site of implantation.
This is especially true when the diseased lumen to be treated is an
aortic aneurysm.
[0034] FIG. 3 shows the same view as FIG. 2 but with balloon 120
partially expanded. This view shows, among other things, the distal
end of graft 140 pulling out from under soft elastic tube 160 as
balloon 120 expands outwardly. FIG. 4 shows balloon 120 fully
expanded with stent 130 and graft 140 in place within a lumen (not
shown). Soft elastic tube 160 is now inside the diameter of graft
140 (although it would not have to be inside the diameter at this
point, so long as it is able to be removed from the inside of graft
140 when the catheter/delivery device is removed from the site of
deployment). FIG. 5 shows balloon 120 deflated and the device ready
for removal in the direction of the arrow shown.
[0035] Also included in the present invention is a method of
inserting a graft system to repair a vessel in need of repair
comprising the steps of inserting a catheter into a vessel to a
location in need of repair, the catheter including the graft system
of the present invention, retracting the drawstring to cause
untying of the strippable crocheted sheath to allow expansion of
the graft, expanding the stent to anchor the stent and the graft
within the vessel, and then removing the catheter.
[0036] FIG. 6 shows the initial placement of the device within an
aortic aneurysm. Guidewire 600 is inserted first according to
methods known in the prior art, and then the catheter holding the
device is advanced along guidewire 600 into position as shown in
FIG. 6. Catheter tip 170 is shown distal to soft tube 160, with
stent 130 disposed within the distal end of graft 140. Strippable
crocheted sheath 150 runs along first iliac leg 620 and over graft
distal region 630 (which is the non-bifurcated region of graft
140). Knots 640 are disposed along strippable crocheted sheath 150
which hold strippable crocheted sheath 150 in place until
drawstring 650 is pulled. The presence of strippable crocheted
sheath 150 maintains graft 140 in its reduced diameter, allowing
easier advancement of the device over guidewire 600, as discussed
above.
[0037] Methods and products are known for tying strippable
crocheted sheath into place over graft 140. Among such methods and
products is that disclosed in detail in U.S. Pat. No. 6,019,785 to
Strecker, which is hereby incorporated herein by reference. In
these methods and products, when a single drawstring is pulled by
the surgeon, the sheath unravels, or otherwise unties, allowing the
graft material to assume a relaxed and expandable
configuration.
[0038] As shown in FIGS. 6 and 7, for example, contralateral limb
660 is not covered by strippable crocheted sheath in this
embodiment. FIG. 7 shows grasping snare 670 pulling contralateral
limb 660 into its iliac artery to achieve the desired placement of
the bifurcated device. Once contralateral limb 660 is in place, the
configuration as shown in FIG. 8A is achieved. In an alternative
embodiment, grasping snare 670 may be unnecessary. In such an
alternative, the device could be advanced distally to a point
beyond its final placement such that the distal end of
contralateral limb 660 passes the aortic bifurcation. Then, prior
to full expansion of the prosthesis, the entire device could be
moved distally while guiding the contralateral limb 660 down into
its respective iliac artery.
[0039] In alternative embodiments, different parts of the graft may
be covered by the removable sheath. For example, FIG. 8B shows an
embodiment where all of the graft is covered by strippable
crocheted sheath 150, and FIG. 8C shows an embodiment where only
graft distal region 630 is covered by strippable crocheted sheath
150.
[0040] FIG. 9 shows the step where drawstring 650 is retracted
which results in the untying of strippable crocheted sheath 150. In
the present invention, strippable crocheted sheath is untied, graft
140 is no longer constrained and may expand to an intermediate
uncompressed state. During expansion, graft 140 shortens somewhat
in length. FIG. 10 shows strippable crocheted sheath completely
removed, with graft 140 fully relaxed in place within the aneurysm.
Stent 130, in this particular embodiment and figure, is now partly
exposed at its distal end due to the relative shortening of graft
140 during expansion upon removal of strippable crocheted sheath
150. Other embodiments, however, are contemplated, and include
situations where the design and graft material are chosen so that
complete coverage of the stent is maintained even after deployment
and expansion.
[0041] Now that strippable sheath 150 has been removed and the
graft has obtained its relaxed dimensions, final adjustments can be
made to the exact placement of the device within the aneurysm. This
can be done through known visualization techniques, including the
use of radiopaque markers disposed on or along the graft or stent
for fluoroscopic positioning. Once final placement is achieved, the
stent can be expanded to secure the device.
[0042] FIG. 11 shows the next step in the deployment process where
balloon 120 is expanded to dilate stent 130, expanding the
prosthesis to its fully expanded state so that the aneurysm neck
portion is occluded by the device. In this embodiment, soft nose
160 expands as stent 130 dilates out of the confines of soft nose
160. Once stent 130 is fully dilated, balloon 120 is deflated and
the catheter is removed, leaving stent 130 lodged in the aneurysm
neck, with graft 140 ready to receive blood flow, all as shown in
FIG. 12.
[0043] FIG. 13 shows a final step whereby the distal ends of graft
140 are attached to their respective iliac artery walls, after some
compression of graft 140 to allow for movement caused, for example,
by pulsetile blood flow and temporal migration. In this embodiment,
simply for purposes of illustration, first iliac leg 620 is stented
into place with stent 710, while contralateral limb 660 is sewn
into place with sutures 700.
[0044] In the embodiment shown in FIG. 13, stent 130 and graft 140
are simply frictionally connected, with graft 140 effectively
pinched between stent 130 and the aortic wall. Optionally and
preferably, graft 140 may be attached to stent 130. Several methods
are known to accomplish this attachment, included sewing, gluing,
or otherwise fastening the two together. This is true also for any
stents which may be used at the distal ends of one or both of the
iliac legs.
[0045] In still other alternatives, a mechanical dilation means,
such as a push rod actuated cam or umbrella spoke network to
forcibly expand the graft, with or without a supporting stent, may
be used to expand to graft to its fully dilated configuration.
Similarly, the prosthesis may be secured at any end thereof, to the
surrounding lumen, by any of a wide variety of attachment means
including but not limited to staples, sutures, stents, stents with
barbs, deformable T-head plastic fasteners, etc.
[0046] Accordingly, while illustrated and described herein with
reference to certain specific embodiments, the present invention is
not intended to be limited to the embodiments and details shown.
Rather, the appended claims are intended to include all embodiments
and modifications which may be made in these embodiments and
details, which are nevertheless within the true spirit and scope of
the present invention.
* * * * *