U.S. patent application number 09/908129 was filed with the patent office on 2001-11-22 for modular endoluminal stent-grafts.
Invention is credited to Dereume, Jean-Pierre, Pinchuk, Leonard.
Application Number | 20010044647 09/908129 |
Document ID | / |
Family ID | 27070653 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010044647 |
Kind Code |
A1 |
Pinchuk, Leonard ; et
al. |
November 22, 2001 |
Modular endoluminal stent-grafts
Abstract
Modular endoluminal stent-grafts include at least two different
sized stent-grafts which are deployed one within the other.
According to one embodiment of the invention, a first stent-graft
is provided having a flared end which is expandable to a first
diameter and a midsection which is expandable to a second diameter
smaller than the first diameter. A second stent-graft is also
provided having an end which is expandable to a diameter which
engages the midsection of the first stent-graft. The first
embodiment of the invention is deployed by expanding the first
stent-graft such that its flared end engages a large diameter
vessel, then expanding the second stent-graft inside the midsection
of the first stent graft and inside a small diameter vessel such
that the second stent graft engages the small diameter vessel and
the midsection of the first stent-graft. According to a second
embodiment of the invention, the midsection of the first
stent-graft is reinforced with a flexible member to restrict the
midsection from ballooning. According to other aspects of the
invention, the first stent-graft is provided with two flared ends
and the second stent graft is provided with or without flared ends.
According to still another embodiment of the invention, three or
more stent-grafts of different expanded diameter are deployed one
within the other.
Inventors: |
Pinchuk, Leonard; (Miami,
FL) ; Dereume, Jean-Pierre; (Brussels, BE) |
Correspondence
Address: |
Ratner & Prestia
PO Box 980
Valley Forge
PA
19312
US
|
Family ID: |
27070653 |
Appl. No.: |
09/908129 |
Filed: |
July 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09908129 |
Jul 18, 2001 |
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09134887 |
Aug 14, 1998 |
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09134887 |
Aug 14, 1998 |
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08806739 |
Feb 27, 1997 |
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08806739 |
Feb 27, 1997 |
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08554694 |
Nov 7, 1995 |
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5628788 |
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Current U.S.
Class: |
623/1.13 ;
623/1.31; 623/903 |
Current CPC
Class: |
A61F 2220/0025 20130101;
A61F 2/90 20130101; A61F 2230/0097 20130101; A61F 2/89 20130101;
A61F 2250/0039 20130101; A61F 2220/005 20130101; A61F 2220/0075
20130101; A61F 2230/008 20130101; A61F 2002/826 20130101; A61F
2220/0058 20130101; A61F 2002/065 20130101; A61F 2/07 20130101;
A61F 2002/075 20130101; A61F 2230/0067 20130101; A61F 2002/072
20130101; A61F 2230/0078 20130101 |
Class at
Publication: |
623/1.13 ;
623/1.31; 623/903 |
International
Class: |
A61F 002/06 |
Claims
1. A modular endoluminal stent-graft system for bridging a lesion
in a blood vessel having a first large diameter on one side of the
lesion and a second small diameter on the other side of the lesion,
said system comprising: a) a first stent-graft having a first end,
a second end, and a midsection, said first end of said first
stent-graft having an expanded diameter equal to or slightly larger
than the first large diameter of the blood vessel, said midsection
of said first stent-graft having an expanded diameter which is
smaller than said expanded diameter of said first end of said first
stent-graft; b) a second stent-graft having a first end, a second
end, and a midsection, said first end of said second stent-graft
having an expanded diameter equal to or slightly larger than said
expanded diameter of said midsection of said first stent-graft and
said second end of said second stent-graft having an expanded
diameter which is equal to or slightly larger than the second small
diameter of the blood vessel, such that in a deployed orientation,
said first end of said first stent-graft is adapted to engage the
first large diameter of the blood vessel, said first end of said
second stent-graft securely engages said midsection of said first
stent-graft to hold said second stent graft substantially fixed
relative to said first stent-graft, and said second end of said
second stent-graft engages the second small diameter of the blood
vessel.
2. A system according to claim 1, wherein: said first end of said
first stent-graft is flared.
3. A system according to claim 2, wherein: said second end of said
first stent-graft is flared.
4. A system according to claim 1, wherein: said first end of said
second stent-graft is flared.
5. A system according to claim 4, wherein: said second end of said
second stent-graft is flared.
6. A system according to claim 1, wherein: at least said midsection
of said first stent-graft is reinforced with a flexible
material.
7. A system according to claim 6, wherein: said flexible material
is selected from the group consisting of polyethylene terphthalate,
nylon, polytetrafluoroethylene, polyolefin, polyamide,
polycarbonate, polycarbonate urethane, and metallic wire.
8. A system according to claim 6, wherein: said flexible material
is selected from the group consisting of sutures, knits, weaves,
braids, wires, and stents.
9. A modular stent-graft system, comprising: a) a first stent-graft
having a first end, a second end, and a midsection, said first end
of said first stent-graft having an expanded first diameter and
said midsection of said first stent-graft having an expanded second
diameter which is smaller than said expanded first diameter; b) a
second stent-graft having a first end, a second end, and a
midsection, said first end of said second stent-graft having an
expanded third diameter equal to or slightly larger than said
expanded second diameter of said midsection of said first
stent-graft, said second end of said second stent-graft having an
expanded fourth diameter equal to or smaller than said third
diameter, such that in a deployed orientation, said first end of
said second stent-graft securely engages said midsection of said
first stent-graft to hold the second stent-graft substantially
fixed relative to said first stent-graft.
10. A system according to claim 9, wherein: said first end of said
first stent-graft is flared.
11. A system according to claim 10, wherein: said second end of
said first stent-graft is flared.
12. A system according to claim 9, wherein: said midsection of said
first stent-graft is reinforced with a flexible material.
13. A system according to claim 12, wherein: said flexible material
is selected from the group consisting of polyethylene terphthalate,
nylon, polytetrafluoroethylene, polyolefin, polyamide,
polycarbonate, polycarbonate urethane, and metallic wire.
14. A system according to claim 12, wherein: said flexible material
is selected from the group consisting of sutures, knits, weaves,
braids, wires, and stents.
15. A system according to claim 9, further comprising: c) a third
stent-graft having a first end, a second end, and a midsection,
said first end of said third stent-graft having an expanded fifth
diameter, wherein said midsection of said second stent-graft has an
expanded sixth diameter equal to or slightly smaller than said
expanded fifth diameter of said first end of said third
stent-graft, such that in a deployed orientation, said first end of
said third stent-graft engages said midsection of said second
stent-graft.
16. A system according to claim 15, wherein: said first end of said
third stent-graft is flared.
17. A system according to claim 1, wherein: said first end of said
second stent-graft is coupled to said first stent-graft by one of
sutures, wires, adhesive and welds.
18. A system according to claim 1, wherein: said first end of said
second stent-graft is coupled to said midsection of said first
stent-graft.
19. A method of bridging a lesion in a blood vessel having a first
large diameter on one side of the lesion and a second small
diameter on the other side of the lesion, said method comprising:
a) obtaining a first stent-graft having a first end, a second end,
and a midsection, said first end of said first stent-graft having
an expanded diameter equal to or slightly larger than the first
large diameter of the blood vessel, said midsection of said first
stent-graft having an expanded diameter which is smaller than said
expanded diameter of said first end of said first stent-graft; b)
obtaining a second stent-graft having a first end, a second end,
and a midsection, said first end of said second stent-graft having
an expanded diameter equal to or slightly larger than said expanded
diameter of said midsection of said first stent-graft and said
second end of said second stent-graft having an expanded diameter
which is equal to or slightly larger than the second small diameter
of the blood vessel; c) deploying said first stent-graft by
expanding said first stent-graft such that said first end of said
first stent-graft engages the first large diameter of the blood
vessel; and d) deploying said second stent-graft by expanding said
second stent-graft such that said first end of said second
stent-graft engages said midsection of said first stent-graft such
that said second stent-graft is substantially fixed relative to
said first stent-graft and said second end of said second
stent-graft engages the second small diameter of the blood
vessel.
20. A method according to claim 19, further comprising: e)
obtaining a third stent-graft having a first end, a second end, and
a midsection; and d) deploying said third stent-graft by expanding
said third stent-graft such that said first end of said third
stent-graft engages said midsection of said second stent-graft.
21. A modular endoluminal stent-graft system for bridging a lesion
in a blood vessel having a first large diameter on one side of the
lesion and a second small diameter on the other side of the lesion,
said system comprising: a) a first stent-graft having a first end,
a second end, and a midsection, said first end of said first
stent-graft having an expanded diameter equal to or slightly larger
than the first large diameter of the blood vessel, said midsection
of said first stent-graft having an expanded diameter which is
smaller than said expanded diameter of said first end of said first
stent-graft; b) a second stent-graft having a first end, a second
end, and a midsection, said first end of said second stent-graft
having an expanded diameter equal to or slightly larger than said
expanded diameter of said midsection of said first stent-graft and
said second end of said second stent-graft having an expanded
diameter which is equal to or slightly larger than the second small
diameter of the blood vessel, such that in a deployed orientation,
said first end of said first stent-graft is adapted to engage the
first large diameter of the blood vessel, said first end of said
second stent-graft engages said midsection of said first
stent-graft, and said second end of said second stent-graft is
adapted to engage the second small diameter of the blood vessel
wherein at least said midsection of said first stent-graft is
reinforced with a flexible material.
22. A modular stent-graft system, comprising: a) a first
stent-graft having a first end, a second end, and a midsection,
said first end of said first stent-graft having an expanded first
diameter and said midsection of said first stent-graft having an
expanded second diameter which is smaller than said expanded first
diameter; b) a second stent-graft having a first end, a second end,
and a midsection, said first end of said second stent-graft having
an expanded third diameter equal to or slightly larger than said
expanded second diameter of said midsection of said first
stent-graft, said second end of said second stent-graft having an
expanded fourth diameter equal to or smaller than said third
diameter, such that in a deployed orientation, said first end of
said second stent-graft engages said midsection of said first
stent-graft wherein at least said midsection of said first
stent-graft is reinforced with a flexible material.
23. A method of bridging a lesion in a blood vessel having a first
large diameter on one side of the lesion and a second small
diameter on the other side of the lesion, said method comprising:
a) obtaining a first stent-graft having a first end, a second end,
and a midsection, said first end of said first stent-graft having
an expanded diameter equal to or slightly larger than the first
large diameter of the blood vessel, said midsection of said first
stent-graft having an expanded diameter which is smaller than said
expanded diameter of said first end of said first stent-graft
wherein at least said midsection of said first stent-graft is
reinforced with a flexible material; b) obtaining a second
stent-graft having a first end, a second end, and a midsection,
said first end of said second stent-graft having an expanded
diameter equal to or slightly larger than said expanded diameter of
said midsection of said first stent-graft and said second end of
said second stent-graft having an expanded diameter which is equal
to or slightly larger than the second small diameter of the blood
vessel; c) deploying said first stent-graft by expanding said first
stent-graft such that said first end of said first stent-graft
engages the first large diameter of the blood vessel; and d)
deploying said second stent-graft by expanding said second
stent-graft such that said first end of said second stent-graft
engages said midsection of said first stent-graft and said second
end of said second stent-graft engages the second small diameter of
the blood vessel.
Description
[0001] This application is a continuation of allowed Ser. No.
08/806,739 filed Feb. 27, 1997 which is a continuation-in-part of
application Ser. No. 08/554,694, entitled "Self-expanding
Endoluminal Stent-graft", filed Nov. 7, 1995, now U.S. Pat. No.
5,628,788, the complete disclosures of which are hereby
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to an implantable prosthesis. In
particular, the invention relates to endoluminal grafts and
stent-grafts which are deployed in a blood vessel which has a
varying diameter. The invention is particularly suited for
repairing the aortic artery and daughter arteries, although it is
not limited thereto.
[0004] 2. State of the Art
[0005] An endoluminal stent-graft typically includes tubular graft
material which is affixed to the inside or outside of a woven
metallic stent and is delivered to the damaged site of a blood
vessel via a catheter. Endoluminal stent-grafts are most often used
to repair blood vessels affected by a variety of lesions such as
stenoses or aneurysms. A typical prior art stent, shown in FIGS.
1-6, is a metallic structure 10 made of braided wire 12 such as
stainless steel, cobalt-chromium-nickel super alloys and
combinations, co-extrusions or braised combinations of the above
with tantalum, gold, platinum and the like. Stents are also made
from memory alloys such as nitinol and the like. Typical stents are
disclosed in U.S. Pat. Nos. 4,655,771 and 4,954,126 to Wallsten,
the complete disclosures of which are hereby incorporated herein by
reference, and in U.K. Patent Number 1,205,743 to Didcott, the
complete disclosure of which is also hereby incorporated herein by
reference. Generally, the wires 12 are braided with a large pick
size, i.e. with relatively large interstices 14 between the wires,
so that axial expansion of the stent causes a diametrical
compression of the stent. Most often the braiding and/or the metal
chosen for the wires yields a resilient stent which is
self-expanding. However, some stents are not self-expanding and are
expanded with the use of a balloon catheter. In the case of
self-expanding stents, the proximal and distal ends 16, 18 of the
stent are usually flared when expanded.
[0006] While endoluminal stents have been used without any graft
material when repairing stenoses, it is now generally preferred to
use a graft material in combination with the stent when repairing
stenoses as well as when repairing aneurysms. The graft material
most often used in endoluminal grafts is a PET or
polytetrafluroethylene (PTFE) material which is folded to reduce
its size and which is attached to one or both ends of a radially
expandable stent by means of sutures. When the stent self-expands
or is balloon expanded, the graft unfolds around the stent. The
above-referenced parent application discloses a stent-graft which
incorporates an improved self-expanding graft material.
[0007] While the primary use of endoluminal stents is to treat
stenoses, stents are also sometimes used in conjunction with graft
material to bridge aneurysms. The advantage of using a stent in
bridging aneurysms is that the expanded stent helps to fix the
graft in place, can eliminate the need for sutures, and may provide
some additional resistance to hoop stress. Prior art FIGS. 2-5
illustrate the deployment of a stent-graft to bridge an
aneurysm.
[0008] Referring now to FIGS. 2-5, the ends of the stent 10 are
axially displaced inside an introducer 20 which includes an inner
catheter 22 having a soft (dilator) tip 24 and an outer sheath 26.
The introducer 20 is delivered through a blood vessel 28 with the
aid of a guide wire 30 which is inserted through the lumen of the
inner catheter 22. The introducer 20 is guided over the guide wire
30 to the site of an aneurysm, in this case two adjacent aneurysms,
namely distal aneurysm 32 and proximal aneurysm 34. With the aid of
fluoroscopy, the introducer 20 is positioned so that the soft tip
24 is located distally relative to the distal aneurysm 32. The
outer sheath 26 is drawn proximally while the inner catheter 22 is
held stationary. This releases the distal end 18 of the stent 10
which self-expands to the inner diameter of the vessel 28 as shown
in FIG. 3. Continued proximal movement of the outer sheath 26
releases the remainder of the stent 10 as shown in FIG. 4 until the
proximal end 16 of the stent 10 expands to the inner diameter of
the vessel 28 proximal of the proximal aneurysm 34 as shown in FIG.
5, after which the introducer 20 and the guide wire 30 are removed
from the vessel 28.
[0009] From the foregoing, it will be appreciated that by using an
appropriately sized stent-graft, the aneurysms 32, 34 in FIGS. 2-5
are effectively bridged utilizing the procedure described above. In
particular, the stent-graft must be long enough so that its
proximal and distal ends extend beyond the aneurysms and expand
into healthy areas of the blood vessel. Moreover, the stent-graft
must be chosen to have the appropriate expanded diameter so that a
good seal is made between the stent-graft and the inner wall of the
blood vessel. However, the diameter should not be so large that
when the stent expands, the outward pressure of the expanding stent
damages the wall of the blood vessel.
[0010] Because of the above considerations, it is difficult or
impossible to bridge an aneurysm with a stent-graft when the
diameter of the blood vessel on either side of the aneurysm differs
by any significant amount. For example, as shown in FIG. 6, the
distal end 18 of a stent-graft 10 is greatly compressed as compared
to the proximal end 16 when the stent-graft is used to bridge
aneurysms 32, 34 where the diameter of the vessel 28 on the
proximal side 28a of the aneurysms 32, 34 is substantially greater
than the diameter of the vessel on the distal side 28b of the
aneurysms 32, 34. Depending on the nature of the particular
stent-graft, this can cause damage to the vessel on the distal side
28b or can result in an inward tapering of the distal end 18 of the
graft to a "cigar shape". In the former situation, the damage can
result in an additional aneurysm or rupture of the vessel. In the
latter situation, the distal end 18 of the graft can obstruct the
flow of blood, or jeopardize the seal between the distal end 18 and
the inner wall of the vessel 28b. In the case of obstruction,
occlusion of the vessel may occur which can be catastrophic to the
patient. In the case of seal weakening, blood will enter into the
aneurysmal sac and promote continued growth of the aneurysm.
[0011] More often than not the vessels of the vascular tree
especially in the abdominal aortic artery exhibit the joining of
vessels having very different diameters. For example, as shown in
FIG. 7, the abdominal aortic artery 50 is the trunk from which the
renal arteries, right 52, left 54 and the iliac arteries, right 56,
left 58 proceed. An aortic aneurysm 60 between the renal arteries
and the iliac arteries is very difficult to bridge since the
diameter of the aortic artery is approximately 25 mm, whereas the
diameter of the iliac artery is about 12 mm. A stent-graft having a
diameter of 27 mm will fit well in the aortic artery, but will be
too large for the iliac artery. A 13 mm diameter stent-graft will
fit well in the iliac artery, but will be too small for the aortic
artery.
[0012] The above-referenced parent application discloses a
bifurcated stent-graft which is useful in repairing an abdominal
aortic aneurysm and iliac aneurysm. The bifurcated graft is located
in the abdominal aortic artery just above the iliac arteries with
its bifurcated end closest to the iliac arteries. The bifurcated
stent-graft effectively bypasses an aneurysm in the aortic artery
and provides a radiopaque bifurcated guide to the iliac arteries.
Once the bifurcated graft is deployed, an additional graft may be
deployed in each of the iliac arteries. The additional grafts are
deployed through the legs of the bifurcated stent-graft. The
bifurcated legs provide separate fluid couplings for the two
additional grafts so that blood can flow from the aortic artery to
both iliac arteries.
[0013] Subsequent to the development of the bifurcated stent-graft
of the parent application, additional discoveries have been made
regarding the use of multiple stent-grafts to bridge vessels of
different diameter. In particular, it is sometimes desirable to
bridge the aortic artery with only one of the iliac arteries.
[0014] In addition, it has been discovered that in some situations
where a stent-graft has been implanted to bridge an aneurysm, the
stent-graft will continue to expand radially long after the time of
implantation. This is particularly likely where there is continuous
progression of aneurysmal disease and dilation of the neck of the
aneurysm. The continued radial expansion of the stent-graft results
in a continued axial shortening of the stent-graft which often
results in the ends of the stent-graft becoming dislodged from the
blood vessel whereupon the prosthesis floats free inside the
aneurysm causing serious danger to the patient.
SUMMARY OF THE INVENTION
[0015] It is therefore an object of the invention to provide
endoluminal stent-grafts which are useful for bridging vessels of
different diameter.
[0016] It is also an object of the invention to provide methods for
using endoluminal stent-grafts to bridge vessels of different
diameter.
[0017] It is still another object of the invention to provide an
endoluminal stent-graft with a limited radial expandability and
limited axial compressibility.
[0018] In accord with these objects which will be discussed in
detail below, the modular endoluminal stent-grafts of the present
invention include at least two different sized stent-grafts which
are deployed one within the other. According to one embodiment of
the invention, a first stent-graft is provided having a flared end
which is expandable to a first diameter and a midsection which is
expandable to a second diameter smaller than the first diameter. A
second stent-graft is also provided having an end which is
expandable to a diameter which engages the midsection of the first
stent-graft. The first embodiment of the invention is deployed by
expanding the first stent-graft such that its flared end engages a
large diameter vessel, then expanding the second stent-graft inside
the midsection of the first stent graft and inside a small diameter
vessel such that the second stent graft engages the small diameter
vessel and the midsection of the first stent-graft. Both the first
and second stent-grafts may be manufactured in a conventional
manner using conventional materials. According to a second
embodiment of the invention, the midsection of the first
stent-graft is reinforced with a flexible member to restrict the
midsection from ballooning due to the outward pressure of the
second stent-graft deployed within the lumen of the first
stent-graft. The reinforcing member may be applied to all or a
portion of the stent-graft. The reinforcing member is also useful
in preventing the stent-graft from ballooning due to the presence
of static blood pressure over time after implantation.
[0019] According to other aspects of the invention, the first
stent-graft is provided with two flared ends and the second stent
graft is provided with or without flared ends.
[0020] According to still another embodiment of the invention,
three or more stent-grafts of different expanded diameter are
deployed one within the other.
[0021] According to another embodiment of the invention, two or
more stent-grafts of different diameter are pre-coupled to each
other prior to deployment and are deployed using a single
introducer in substantially one step.
[0022] According to still other aspects of the invention, the
second and/or third stent-grafts are reinforced with a flexible
member to restrict the midsection from ballooning.
[0023] Additional objects and advantages of the invention will
become apparent to those skilled in the art upon reference to the
detailed description taken in conjunction with the provided
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a side elevation view of a prior art stent;
[0025] FIG. 2 is a broken side elevation view in partial section of
a prior art stent introducer during a first stage of deployment in
a blood vessel with two adjacent aneurysms;
[0026] FIGS. 3-5 are views similar to FIG. 2 showing the subsequent
stages of deployment according to the prior art;
[0027] FIG. 6 is a view similar to FIG. 5 showing a blood vessel
which has different diameters on either side of the aneurysms;
[0028] FIG. 7 is a schematic view of an abdominal aortic
aneurysm;
[0029] FIG. 8 is a side elevation view of a first stent-graft in a
modular system according to the invention;
[0030] FIG. 9 is a schematic view of the stent-graft of FIG. 8
deployed in an abdominal aortic aneurysm;
[0031] FIG. 10 is a view similar to FIG. 9 showing a second
stent-graft in a modular system according to the invention deployed
inside the first stent-graft and inside the right iliac artery;
[0032] FIG. 11 is a side elevation view of a second embodiment of a
first stent-graft according to the invention having a flexible
reinforcement;
[0033] FIG. 11a is a view similar to FIG. 11 of a stent-graft
according to the invention having another type of flexible
reinforcement;
[0034] FIG. 11b is a view similar to FIG. 11a of a stent-graft
according to the invention having still another type of flexible
reinforcement;
[0035] FIG. 12 is a schematic view of a modular stent-graft system
according to the invention having three stent-grafts where the
second is deployed inside the first and the third is deployed
inside the second;
[0036] FIG. 13 is a schematic view of a modular stent-graft system
according to the invention in which stent-grafts of different
diameter are pre-coupled to each other prior to deployment; and
[0037] FIG. 14 is a reduced schematic view of the stent-graft
system of FIG. 13 in a "pulled-down" state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] Referring now to FIGS. 8-10, a first stent-graft 100 in a
modular system according to the invention has a flared proximal end
102, a flared distal end 104, and a midsection 106. The proximal
end 102 is provided with an expanded diameter equal to or slightly
larger than the inner diameter of the proximal end of an aneurysm
that is to be bridged, e.g. the neck 108 of the abdominal aortic
artery 50. The midsection 106 is provided with an expanded diameter
equal to or slightly smaller than the inner diameter of the distal
end 55 of an aneurysm that is to be bridged, e.g. the right iliac
artery 56. The stent-graft 100 may be manufactured according to
conventional methods with conventional materials, but is preferably
manufactured using the methods and materials described in the
above-referenced parent application. A second stent-graft 200 in a
modular system according to the invention has a proximal end 202, a
distal end 204, and a midsection 206. The expanded diameter of the
proximal end 202 is dimensioned to engage the expanded interior of
the midsection 106 of the first stent-graft 100 and the expanded
diameter of the distal end 204 is dimensioned to engage the
interior of the distal end of an aneurysm that is to be bridged,
e.g. the right iliac artery 56. The stent-graft 200 may be
manufactured according to conventional methods with conventional
materials, but is preferably manufactured using the methods and
materials described in the above-referenced parent application.
[0039] The modular stent-grafts 100 and 200 are deployed in the
following manner which is illustrated by way of example in FIGS. 9
and 10 which depict deployment in an abdominal aortic aneurysm. The
first stent-graft 100 is compressed into an introducer (not shown)
and delivered to the a point distal of the renal arteries 52, 54
using conventional methods (see FIGS. 2-5). The stent-graft 100 is
deployed such that the proximal end 102 of the stent-graft 100
expands into the neck 108 of the aortic artery distal of the renal
arteries 52, 54 but proximal of the aortic aneurysm 60. The
expanded distal end 104 rests in the aneurysm itself and serves to
stabilize the position of the midsection 106 as shown in FIG. 9.
The introducer (not shown) is withdrawn and the second stent-graft
200 is compressed into the same or another introducer and delivered
through the first stent-graft 100 to a point within the right iliac
artery 56. The second stent-graft 200 is deployed such that the
proximal end 202 of the second stent-graft expands into the
midsection 106 of the first stent-graft 100 and the distal end 204
of the second stent-graft expands into the right iliac artery.
[0040] As mentioned above, both the first and second stent-grafts
may be manufactured according to conventional methods with
conventional materials or using the methods and materials described
in the above-referenced parent application. In addition, the second
stent-graft may be made with fewer wires and/or with smaller wires
in order that it fit properly in the iliac artery. The first
stent-graft 100 may also be provided with midsection reinforcement
as shown in FIG. 11.
[0041] Turning now to FIG. 11, there is illustrated a stent-graft
100' which is similar to the first stent-graft 100 described above.
The stent-graft 100' has a flared proximal end 102', a flared
distal end 104', and a midsection 106'. According to this
embodiment, the stent-graft 100' has a flexible reinforcement 105'
attached to the midsection 106' which restricts the midsection from
ballooning when another (second) stent-graft is expanded inside the
midsection. The flexible reinforcement 105' may be formed from
sutures, knits, weaves, braids, wires, or another stent. The
reinforcement 105' may be attached to the inside or the outside of
the midsection. Suitable materials for the reinforcement 105'
include polyethylene terphthalate, nylon, polytetrafluoroethylene,
polyolefin, polyamide, polycarbonate, polycarbonate urethane,
metallic wire such as tantalum, stainless steel, titanium, annealed
cobalt-chromium-nickel, etc. The reinforcement may be attached to
the stent by suturing, gluing, hooks, welds or any other method
which does not interfere with the compression of the stent. As
shown in FIG. 11, the reinforcement 105' is a substantially
continuous member or members. In addition, such a reinforcement may
be applied to all or part of the second stent-graft 200 described
above in order to prevent ballooning of the second stent-graft in
regions of high blood pressure, or in instances where the
stent-graft is compressed axially during deployment.
[0042] Turning now to FIG. 11a, there is shown a stent-graft 100"
which is similar to the first stent-graft 100 described above. The
stent-graft 100" has a flared proximal end 102", a flared distal
end 104", and a midsection 106". According to this embodiment, the
stent-graft 100" has a flexible reinforcement 105" attached to the
midsection 106" and extending along substantially its entire
length. In addition, in this embodiment, the reinforcement is
formed from a series of discrete members which are axially spaced
apart from each other. An advantage of using discrete members is
that the stent-graft can be trimmed on the operating table without
risking detachment of the ends of the reinforcement. This advantage
can also be achieved with a reinforcement which is inlay knitted or
woven into the graft component of the stent-graft, a reinforcement
which is added to the outside of the stent-graft, or a
reinforcement which is located between the stent and the graft.
[0043] FIG 11b shows a stent-graft 100'" which is similar to the
first stent-graft 100 described above. The stent-graft 100'" has a
flared proximal end 102'", a flared distal end 104'", and a
midsection 106'". According to this embodiment, the stent-graft
100'" has a first flexible reinforcement 105'" located between the
proximal end 102'" and the midsection 106'" and a second flexible
reinforcement 107'" located between the distal end 104'" and the
midsection 106'". An advantage of this configuration is that it
allows a small amount of additional axial compressibility which can
be helpful during deployment. For example, if the stent is too
long, it can be compressed axially to fit in the desired space. In
addition, the pitch angle of the reinforcements 105'", 107'" can be
made lower to add a small amount of longitudinal compressibility to
the stent-graft while still maintaining a restriction on the radial
expandability of the stent-graft.
[0044] Common to all of the embodiments of the reinforced
stent-graft is the feature that the reinforcement is flexible
enough to allow the stent-graft to be pulled down to a small
diameter for delivery to the deployment site, but be strong enough
to limit the radial expansion of the stent-graft beyond a diameter
which is substantially equal to the resting diameter of the
stent-graft.
[0045] The modular stent-graft system of the invention may include
more than two stent-grafts. For example, as shown in FIG. 12, a
modular system may include three stent-grafts 300, 400, 500 for
bridging two aneurysms 604, 608 in a blood vessel 600 which
exhibits three different diameters 602, 606, 610. As shown in FIG.
12, the first stent-graft 300 has a flared proximal end 302, a
non-flared distal end 304, and a midsection 306. The second
stent-graft 400 has a non-flared proximal end 402, a non-flared
distal end 404, and a midsection 406. The third stent-graft 500 has
a flared proximal end 502, a non-flared distal end 504, and a
midsection 506. The flared proximal end 302 of the first
stent-graft 300 has an expanded diameter which fits securely in the
large diameter portion 602 of the blood vessel 600 proximal of the
first aneurysm 604. The second stent-graft 400 has a substantially
constant expanded diameter which causes its proximal end 402 to fit
securely in the midsection 306 of the first stent-graft 300 and its
midsection 406 to fit securely in the smaller diameter section 606
of the blood vessel 600 between the first aneurysm 604 and the
second aneurysm 608. The flared proximal end 502 of the third
stent-graft 500 has an expanded diameter which fits securely in the
midsection 406 of the second stent-graft 400; and the non-flared
distal end 504 has an expanded diameter which fits securely in the
smallest diameter portion 610 of the blood vessel 600 distal of the
second aneurysm 608. The modular stent-grafts of FIG. 12 are
deployed in a manner similar to the stent-grafts shown in FIG. 10,
i.e. by deploying the proximal stent-graft first, and then
following with distal stent-grafts. Although FIG. 12 shows three
stent-grafts with increasingly smaller diameters, the proximal to
distal diameter change need not be from larger to smaller. For
example, if the aneurysm 608 were located proximal of the aneurysm
604, the stent-grafts could be deployed in a different order or in
the same order but with their proximal and distal ends reversed.
That is, the stent-graft 400 could be deployed first and the
stent-grafts 300 and 500 could be deployed inside the stent-graft
400. In this situation, it would be advantageous for the entire
length of the stent-graft 400 to be reinforced. Alternatively, the
stent-graft 300 could be deployed first with its end 302 being
deployed distally, etc.
[0046] Referring now to FIGS. 13 and 14, a modular stent-graft
system 700 is shown. The stent-graft system 700 has three
stent-grafts 300', 400', and 500' which are similar to the
stent-grafts 300, 400, and 500 described above. As shown in FIG.
13, the primed reference numerals (e.g. 302') refer to features of
the stent-grafts 300', 400', and 500' which are similar to features
of the stent-grafts 300, 400, and 500 described above. According to
this embodiment of the invention, the proximal end 402' of the
stent-graft 400' is pre-coupled to the midsection 306' of the
stent-graft 300' and the proximal end 502' of the stent-graft 500'
is pre-coupled to the midsection 406' of the stent-graft 400'. The
pre-coupling may be effected at the time of manufacture, or by a
practitioner prior to deployment of the modular stent-graft system.
As shown in FIG. 13, the pre-coupling is accomplished with sutures
401' and 501'. However, the stent-grafts may also be coupled to
each other by wires, adhesives, welds, or by using any other
suitable coupling method. After the stent-grafts 300', 400', and
500' are coupled to each other, they are "pulled down" as a single
unit with the aid of an introducer to a compressed state as shown
in FIG. 14 for deployment.
[0047] There have been described and illustrated herein several
embodiments of modular endoluminal stent-grafts and methods for
their use. While particular embodiments of the invention have been
described, it is not intended that the invention be limited
thereto, as it is intended that the invention be as broad in scope
as the art will allow and that the specification be read likewise.
Thus, while particular dimensions and materials have been
disclosed, it will be appreciated that other dimensions and
materials could be utilized. Also, while the stent-grafts have been
shown for use in bridging aneurysms, it will be recognized that the
modular system of stent-grafts could be used to bridge other types
of lesions. Moreover, while particular configurations have been
disclosed in reference to flared ends and reinforcing members, it
will be appreciated that other configurations could be used as
well. For example, the modular stent-graft 100 described with
reference to FIG. 10 could be provided with a single flared end,
the proximal end, rather than two flared ends, in order to fit in
certain tortuous arteries. Also, it is possible to utilize a
bifurcated stent (as shown in the parent application) as a
component in a modular stent system and use an occluding device to
block one of its legs.
[0048] It will therefore be appreciated by those skilled in the art
that yet other modifications could be made to the provided
invention without deviating from its spirit and scope as so
claimed.
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