U.S. patent application number 09/970576 was filed with the patent office on 2002-01-24 for layered endovascular graft.
Invention is credited to Chobotov, Michael V..
Application Number | 20020010508 09/970576 |
Document ID | / |
Family ID | 22068639 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020010508 |
Kind Code |
A1 |
Chobotov, Michael V. |
January 24, 2002 |
Layered endovascular graft
Abstract
A endovascular graft having at least two thin wall graft
members, with at least one of the thin wall graft members
configured to be deployed within a lumen of another thin wall graft
member. The thin wall graft members may be coupled or connected to
each other so as to allow relative axial displacement of the
sections, or they may be separate members that have dimensions and
a configuration to allow coaxial deployment within inner lumens of
each other. By having multiple thin wall graft member, the graft
may be built up within a patient's vasculature in steps through a
delivery catheter system that is smaller in profile and more
flexible than a delivery catheter system configured to deliver a
single component graft. The graft of the invention may be delivered
percutaneously or intraoperatively.
Inventors: |
Chobotov, Michael V.; (Santa
Rosa, CA) |
Correspondence
Address: |
William B. Anderson
Heller Ehrman White & McAuliffe LLP
Suite 600
4350 La Jolla Village Drive
San Diego
CA
92122
US
|
Family ID: |
22068639 |
Appl. No.: |
09/970576 |
Filed: |
October 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09970576 |
Oct 4, 2001 |
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09200317 |
Nov 25, 1998 |
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60066301 |
Nov 25, 1997 |
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Current U.S.
Class: |
623/1.44 |
Current CPC
Class: |
A61F 2002/072 20130101;
A61F 2250/0007 20130101; A61F 2250/0063 20130101; A61F 2002/065
20130101; A61F 2/90 20130101; A61F 2002/075 20130101; A61F 2/07
20130101; A61F 2220/0033 20130101 |
Class at
Publication: |
623/1.44 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. An endovascular graft for supporting a preselected length of a
patient's body lumen comprising a plurality of separate thin wall
graft members configured to be layered in a deployed state with at
least two of the thin wall graft members having a length greater
than the preselected length of the patient's body lumen.
2. The endovascular graft of claim 1 wherein no single thin wall
graft member has sufficient mechanical strength in a deployed state
to provide a desired amount of support for the preselected length
of a patient's body lumen.
3. The endovascular graft of claim 2 wherein the thin wall graft
members are configured to provide sufficient mechanical strength to
provide a desired amount of support for the preselected length of
the patient's body lumen in portions of the graft where at least
two of the thin wall graft members are overlapped.
4. The endovascular graft of claim 2 wherein the graft comprises at
least 3 thin wall graft members and the thin wall graft members are
configured to provide sufficient mechanical strength to provide a
desired amount of support for the preselected portion of the
patient's body lumen only in portions of the graft where all of the
thin wall graft members are overlapped.
5. The graft of claim 1 wherein an inner most thin wall graft
member has an axial length substantially greater than all other
thin wall graft members such that the inner-most thin wall graft
member can extend longitudinally beyond a distal end and a proximal
end of all other thin wall graft members when deployed.
6. The graft of claim 1 wherein the thin wall graft members are
configured to be expanded to a transverse dimension of up to about
40 mm and constrained to a maximum outer transverse dimension of
down to about 3 mm.
7. The graft of claim 1 wherein the separate thin wall graft
members are individually deliverable.
8. The graft of claim 1 wherein each thin wall graft member further
comprises an anchoring mechanism at both ends and at least two of
the thin wall graft members have a longitudinal length sufficient
to span the preselected length of the patient's body lumen and
engage tissue of sufficient integrity to support the anchoring
mechanisms at both ends of the at least two thin wall graft
members.
9. A method of deploying an endovascular graft within a body
passageway of a patient comprising: a) providing an endovascular
graft comprising at least two thin wall graft members configured to
be layered in a deployed state; b) percutaneously delivering a
first thin wall graft member through a low profile delivery
catheter system to a desired site within a passageway of a
patient's body and deploying the first thin wall graft member at
the desired site; c) percutaneously delivering a second thin wall
graft member through a low profile delivery catheter system and
positioning the second thin wall graft member within a longitudinal
lumen of the deployed first thin wall graft member; and d)
deploying the second thin wall graft member within the longitudinal
lumen of the deployed first thin wall graft member.
10. The method of claim 9 wherein an inner most thin wall graft
member extends longitudinally beyond the other thin wall graft
members and engages the artery wall directly.
11. A method of deploying an endovascular graft within a body
passageway of a patient comprising: a) providing an endovascular
graft comprising at least two thin wall graft members configured to
be layered in a deployed state; b) percutaneously delivering a
first thin wall graft member through a low profile delivery
catheter system to a preselected site within a passageway of a
patient's body; c) percutaneously delivering a second thin wall
graft member through a low profile delivery catheter system and
positioning the second thin wall graft member within a longitudinal
lumen of the first thin wall graft member; and d) deploying the
second thin wall graft member within the longitudinal lumen of the
deployed first thin wall graft member and simultaneously deploying
the first thin wall graft member until the first and second thin
wall graft members are in a desired configuration within the
passageway of the patient.
12. The method of claim 11 wherein an inner most thin wall graft
member extends longitudinally beyond the other thin wall graft
members and engages the artery wall directly.
13. The method of claim 11 wherein the passageway of the patient
has a curvature and the thin wall graft members are progressively
deployed such that each added thin wall graft member is offset in
the same longitudinal direction through the curvature of the
patient's body passageway so that there are at least two layers of
thin wall graft member over every portion of the preselected length
of the patient's body passageway but each added thin wall graft
member adds to the length of the graft in the amount of
longitudinal offset and is sufficiently short in longitudinal
length to absorb the curvature of the passageway without undue
kinking or folding.
14. A kit comprising an endovascular graft having at least a first
thin wall graft member and a second thin wall graft member with the
second thin wall graft member configured to fit and be deployed
within a longitudinal lumen of the first thin wall graft
member.
15. The kit of claim 14 wherein the first and second thin wall
graft members configured to be deployed within a low profile
delivery catheter system.
16. The kit of claim 15 wherein the first and second thin wall
graft members are configured to be delivered through a delivery
catheter system with a maximum distal outer transverse dimension of
up to about 4 mm.
17. An endovascular graft for supporting a preselected length of a
patient's body lumen comprising a plurality of thin wall graft
members that are linked so as to allow relative longitudinal
movement and that are configured to be layered in a deployed state
with at least two of the thin wall graft members having a length
greater than the preselected length of the patient's body
lumen.
18. The endovascular graft of claim 17 wherein the plurality of
thin wall graft members are configured to be telescopically linked
to allow for longitudinal extension during delivery and layering in
a deployed state.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of Provisional
Application Ser. No. 60/066,301, filed Nov. 25, 1997. Priority is
hereby claimed to Provisional Application Ser. No. 60/066,301,
which also incorporated by reference in its entirety herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a system and method for the
treatment of disorders of the vasculature. More specifically, a
system and method for treatment of thoracic or abdominal aortic
aneurysm and the like, which is a condition manifested by expansion
and weakening of the aorta. Such conditions require intervention
due to the severity of the sequelae, which frequently is death.
Prior methods of treating aneurysms have consisted of invasive
surgical methods with graft placement within the affected vessel as
a reinforcing member of the artery. However, such a procedure
requires a surgical cut down to access the vessel, which in turn
can result in a catastrophic rupture of the aneurysm due to the
decreased external pressure from the surrounding organs and
tissues, which are moved during the procedure to gain access to the
vessel. Accordingly, surgical procedures have a high mortality rate
due to the possibility of the rupture discussed above in addition
to other factors. Other factors can include poor physical condition
of the patient due to blood loss, anuria, and low blood pressure
associated with the aortic abdominal aneurysm. An example of a
surgical procedure is described in a book entitled Surgical
Treatment of Aortic Aneurysms by Denton A. Cooley, M.D., published
in 1986 by W. B. Saunders Company.
[0003] Due to the inherent risks and complexities of surgical
procedures, various attempts have been made in the development of
alternative methods for deployment of grafts within aortic
aneurysms. One such method is the noninvasive technique of
percutaneous delivery by a catheter-based system. Such a method is
described in Lawrence, Jr. et al. in "Percutaneous endovascular
graft: experimental evaluation", Radiology (May 1987). Lawrence
described therein the use of a Gianturco stent as disclosed in U.S.
Pat. No. 4,580,568. The stent is used to position a Dacron fabric
graft within the vessel. The Dacron graft is compressed within the
catheter and then deployed within the vessel to be treated. A
similar procedure has also been described by Mirich et al. in
"Percutaneously placed endovascular grafts for aortic aneurysms:
feasibility study," Radiology (March 1989). Mirich describes
therein a self-expanding metallic structure covered by a nylon
fabric, with said structure being anchored by barbs at the proximal
and distal ends.
[0004] One of the primary deficiencies of the existing percutaneous
devices and methods has been that the grafts and the delivery
catheters used to deliver the grafts are relatively large in
profile, often up to 24 French and greater, and stiff in bending.
The large profile and bending stiffness makes delivery through the
irregular and tortuous arteries of diseased vessels difficult and
risky. In particular, the iliac arteries are often too narrow or
irregular for the passage of a percutaneous device. In addition,
current devices are particularly challenged to reach the deployment
sizes and diameters required for treatment of lesions in the aorto
and aorto-iliac regions. Because of this, non-invasive percutaneous
graft delivery for treatment of aortic aneurysm is not available to
many patients who would benefit from it.
[0005] While the above methods have shown some promise with regard
to treating thoracic and abdominal aortic aneurysms with
non-invasive methods, there remains a need for an endovascular
graft system which can be deployed percutaneously in a small
diameter flexible catheter system. The present invention satisfies
these and other needs.
SUMMARY OF THE INVENTION
[0006] The present invention is directed generally to a system and
method for treatment of a body lumen or passageway within a
patient's body. More specifically, the invention is directed to an
endovascular graft for treatment of weakened or diseased blood
vessels which has at least two thin wall graft members which are
configured to be nested or layered over each other in a deployed
state. By layering a plurality of thin wall graft members, each
layer can be delivered by a smaller more flexible catheter delivery
system than is used for conventional single graft systems. The
system of the present invention may delivered intraoperatively, but
is preferably delivered percutaneously.
[0007] One embodiment of the invention is a graft for supporting a
preselected length of a patient's body lumen or passageway that is
created from at least two separate thin wall graft members. The
thin wall graft members are configured to be nested or layered when
deployed in an overlapping fashion that combines the strength of
the members in the areas or portions that are overlapped. One
advantage of such a system and method is that each individual thin
wall graft member can be constructed with less bulk and material
mass than would be required for a single component graft of similar
strength. This allows each separate thin wall graft member to have
a smaller more flexible profile in a compressed or constricted
state and be deliverable through a smaller and more flexible
delivery system which improves access to preselected lengths of
compromised or diseased body lumens.
[0008] The graft can be configured so that no single component or
thin wall graft member has sufficient mechanical strength to
provide a desired amount of support for a preselected length of a
patient's body lumen. The thin wall graft members can be designed
so that a desired amount of mechanical strength can be achieved
with two or more layers or overlapped portions of the graft. In
some indications, it may be desirable to have three, four, five or
more layers required to achieve the desired amount of mechanical
strength and support for the patient's body lumen. While a graft
requiring more layers for sufficient strength may be more time
consuming to deploy, each thin wall graft member or component can
be made correspondingly thinner and with a lower more flexible
profile in a constrained or compressed state. This allows a
correspondingly smaller and more flexible catheter delivery system
to be used to access the preselected length of body lumen to be
treated.
[0009] In some embodiments, it may be preferable to have the
inner-most and lastly deployed thin wall graft member be of a
longitudinal length greater than the previously deployed thin wall
graft members, individually, or cumulatively as deployed. In this
way, the lastly deployed thin wall graft member can extend
longitudinally from one or both ends of the graft and provide a
smooth transition into the graft for blood flow and a smooth inner
surface for the graft in its final deployed state.
[0010] Generally it is desirable for the preselected length of a
patient's body lumen which is compromised or requires treatment to
be completely spanned by at least the number of thin wall graft
members required to achieve a desired amount of mechanical strength
and support. In this way, each thin wall graft member that provides
a portion of the requisite desired strength can be anchored with
appropriate anchoring mechanisms in tissue that is healthy or of
sufficient integrity to be capable of supporting the anchoring
mechanisms. Each thin wall graft member is typically equipped with
at least one anchoring mechanism at each end to prevent the thin
wall graft member from being displaced from the deployment site and
to facilitate sealing of the graft member against an inside surface
of the patient's body lumen or vessel.
[0011] In an alternative embodiment of a graft of the present
invention, thin wall graft members are linked to allow relative
longitudinal movement or displacement of the members. In a
preferred embodiment, each thin wall graft member is connected to
an adjacent member in a telescopic manner. This allows the graft
members to be extended longitudinally so that only one thickness of
graft member need be compressed or constrained for loading of the
graft into a delivery catheter system, except for the short lengths
of overlapped portion where the ends of the thin wall graft members
are joined. This provides some of the advantages of the separate
individually deliverable thin wall graft members while maintaining
an integral structure. The telescoping graft can be deployed by
positioning each thin wall graft member within an adjacent thin
wall graft member after exiting the distal end of the delivery
catheter system. The graft is then expanded as a whole at a
preselected site within the patient's body lumen. Alternatively,
the graft may be deployed one thin wall graft member at a time,
with each graft member deployed and expanded radially in a desired
position as it exits the delivery catheter system.
[0012] These and other advantages of the invention will become more
apparent from the following detailed description of the invention
when taken in conjunction with the accompanying exemplary
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows an elevational view of an endovascular graft
having features of the invention.
[0014] FIG. 2 shows a transverse cross section of the endovascular
graft of FIG. 1 taken at lines 2-2 of FIG. 1.
[0015] FIG. 3 shows a longitudinal cross sectional view of the
endovascular graft of FIG. 1 taken at lines 3-3 of FIG. 1.
[0016] FIG. 4 is an elevational view of a catheter delivery system
suitable for delivery of a graft having features of the
invention.
[0017] FIG. 5 is a transverse cross sectional view of the catheter
delivery system of FIG. 4 taken at lines 5-5 in FIG. 4.
[0018] FIG. 6 is a longitudinal cross sectional view of a graft
having features of the invention deployed in a patient's body
lumen.
[0019] FIG. 7 is an elevational view in section of a bifurcated
embodiment of a graft having features of the invention.
[0020] FIG. 8 is a transverse cross sectional view of the
endovascular graft of FIG. 7 taken at lines 8-8 of FIG. 7.
DETAILED DESCRIPTION
[0021] An endovascular graft having features of the invention
allows for minimally invasive surgical repair or treatment of
aneurysms, arteriovenous fistula, and other vascular diseases and
injuries of the type found in the aorta and aorto-iliac bifurcation
of the human anatomy. The graft can be delivered via a catheter
delivery system to the site of the disease or injury, where it is
assembled and deployed to provide an internal bypass conduit for
blood flow through the diseased, injured or otherwise compromised
artery. Isolation of the lesion is thereby achieved, eliminating
the risk associated with loss of flow path integrity e.g. rupture
of an aneurysm.
[0022] The graft is typically made of a plurality of tubular
prostheses or thin wall graft members, each of which is constructed
using a small support structure and a very thin graft material such
as Dacron.TM. or ePTFE. Each component prosthesis or thin wall
graft member is nested, laminated or layered in situ to form a
completed structurally sound stent-graft. Each component is
delivered sequentially, overlapping partially or completely the
component or components previously deployed. For bifurcated
applications, an initial bifurcated laminate, component or thin
wall graft member can be positioned and followed by multiple
tubular thin wall graft members into each leg of the original
bifurcated graft member. Alternatively, each component or graft
member may be of bifurcated construction and be sequentially
laminated or deployed in place within a preselected portion of a
patient's body lumen or vessel. Progressive overlap of thin wall
graft members can be used to traverse preselected portions of a
patient's body lumen that have significant angulation so long as
there are sufficient layers of thin wall graft member built up over
the entire compromised preselected portion of the lumen. For body
lumens with high angulation, this method can incorporate the use of
thin wall graft members or components having a relatively short
longitudinal length so as to decrease the tendency of each graft
member to buckle or fold on itself as a result of conforming to the
angulation.
[0023] The thin wall graft members can contain deformable wire at
their proximal and distal ends to allow anchoring to the body lumen
wall in locations proximal and distal the compromised or diseased
portion of the body lumen. The deformable wire portions or
anchoring mechanisms can be used to secure the graft to the lumen
wall of the patient, or to secure the thin wall graft members to
each other. The deformable wires can be self expanding from a
constrained state or balloon expandable. In addition to the
deformable wires, adjacent thin wall graft members can be secured
to each other or the lumen wall with hooks or suitable polymer
adhesives, such as cyanoacrylate compounds. Size differences
between the various graft members that make up a graft can be
determined by specific materials, architectures and applications.
Each graft member can have radiopaque markers or materials to
facilitate imaging of the graft members during delivery and
deployment. The number, size and shape of the thin wall graft
members can be selected from a standard set or adjusted so as to
allow tailoring of the final device shape to a patient's specific
anatomy, and can be defined with the assistance of a flouroscopic
imaging, spiral CT angiography or MRI.
[0024] The nested or layered approach to deploying the thin wall
graft members described herein will allow each member to be
smaller, more flexible, and have a lower profile than would a
single element device typically used to treat the same body lumen.
While each individual graft member may lack the necessary
mechanical characteristics or properties of a completed graft or
device, the aggregate assembly of all of the components in situ
will achieve the required structural objectives. These objectives
include strength, stiffness, and nonporosity necessary for device
patentcy, hemodynamic sealing, and prevention of perigraft leakage.
This approach will allow for improved percutaneous delivery through
a delivery catheter system to preselected portions of a body lumen
using smaller diameter delivery catheters than those typically
used.
[0025] A nested or layered approach used for deploying tubular
members can also be used for treatment of occlusive disease using
stents and stent-grafts. A series of concentric stents that
converge concentrically into position for deployment can be used to
achieve similar benefits of delivery flexibility and low profile.
During delivery the stent components would be extended linearly in
telescopic fashion within a delivery catheter, with each successive
component or stent member sized to fit inside the adjacent stent
member or component. Once the leading end of the series of
components of stent members reaches a preselected lesion site
within a patient's body lumen, the remaining stent members or
components are moved into position for deployment and completion
and consolidation of the device.
[0026] Referring to FIG. 1, a thin wall graft member 10 is shown
having a frame 11, a first anchoring mechanism 12, a second
anchoring mechanism 13, and a tubular membrane 14 disposed within
and secured to the frame. FIG. 2 shows a transverse cross section
of the thin wall graft member 10 of FIG. 1 with the membrane 14
disposed within and secured to the frame 11. FIG. 3 is a
longitudinal cross section of the thin wall graft member 10 of FIG.
1 with the membrane 14 disposed within the frame 11 and first
anchoring mechanism 12 disposed at a first end 15 of the member and
a second anchoring mechanism 13 disposed at a second end 16 of the
member.
[0027] The graft can be configured so that no single component or
thin wall graft member has sufficient mechanical strength to
provide a desired amount of support for a preselected length of a
patient's body lumen. The thin wall graft members can be designed
so that a desired amount of mechanical strength can be achieved
with two or more layers or overlapped portions of the graft. In
some indications, it may be desirable to have three, four, five or
more layers required to achieve the desired amount of mechanical
strength and support for the patient's body lumen. The frame 11 is
made from an expandable wire 17, preferably a pseudoelastic alloy
such as NiTi alloy, but can also be made from a high strength
material such as stainless steel or Co--Cr--Ni alloys such as MP35N
and the like.
[0028] The material of the frame has a diameter or transverse
dimension of about 0.010 inches, but can be from about 0.005 to
about 0.016 inches. The first anchoring mechanism and second
anchoring mechanism 13 are made of materials similar to those of
the frame. The anchoring mechanisms 12 and 13 are of NiTi alloy
having a transverse dimension of about 0.01 inches, but can be from
about 0.005 to about 0.016 inches in transverse dimension. Although
the thin wall graft member 10 is shown with a frame 11, the graft
member can be constructed without the frame and be supported by
anchoring mechanisms 12 and 13 alone.
[0029] The membrane 14 is preferably made from Dacron.TM. or ePTFE
fabric but can be of any other suitable thin material that can
impede the flow of blood or other bodily fluids. Additional
suitable materials can include polyurethane, polyvinylchloride,
PET, PEEK and the like. The thickness of the membrane 14 is about
0.004 inches, but can be from about 0.002 to about 0.008
inches.
[0030] The thin wall graft member 10 is generally longer than the
compromised tissue or aneurysm of the patient's body lumen, and is
about 6 to about 20 cm, preferably about 8 to about 12 cm. The
transverse dimension of the thin wall graft member is about 15 to
about 40 mm, preferably about 20 to about 35 mm. Although the
maximum transverse dimension of the graft member 10 is as described
above, the graft member can be expanded or self expanding to any
size up to the maximum transverse dimension and engage a lumen wall
in which the graft member is being deployed. The graft member 10
will generally be sized to have a slightly larger maximum
transverse dimension than the transverse dimension of the vessel or
lumen within which it is to be deployed. This allows for the
anchoring mechanisms 12 and 13 and frame 11 to engage the inside
surface of the body lumen and be secured and at least partially
sealed thereto.
[0031] The graft member 10 is compressible or constrainable to a
smaller transverse dimension for loading into a delivery catheter
system. The smallest transverse dimension that the graft member 10
can be constrained to for loading and delivery into and out of a
suitable delivery catheter is the minimum transverse dimension. The
minimum transverse dimension of the graft member 10 in a
constrained state is about 4 mm, but can be up to about 6 mm.
Preferably, the minimum transverse dimension of the graft member is
about 2 to about 4 mm.
[0032] FIG. 4 is an elevational view of a delivery catheter 21
having a proximal end 22, a distal end 23, and a distal section 24.
Luer connector 25 is disposed at the proximal end 22 of the
delivery catheter. The delivery catheter 21 is constructed using
common guiding or delivery catheter methods and can be of a solid
polymer material or optionally can have a mesh, coil or braid of a
suitable high strength metal or fiber embedded therein. FIG. 5 is a
transverse cross sectional view of the delivery catheter 21 shown
in FIG. 4 taken at lines 5-5 in FIG. 4 at the distal section 24 of
the delivery catheter. The delivery catheter 21 has a lumen 26
extending the length of the catheter which has an inner diameter of
about 4 to about 5 mm. The wall 27 of the distal section 24 has a
thickness of about 0.01 inches, but can have a thickness of about
0.005 to about 0.05 inches. The length of the delivery catheter 21
is about 20 to about 50 cm, but can be about 10 to about 150 cm.
The delivery catheter 21 preferably has a low friction surface
inside the lumen to facilitate deployment of thin wall graft
members. The wall 27 of the delivery catheter 21 is shown as having
a single polymer layer, but may be constructed of multiple
concentric or eccentric layers, preferably with the inner-most
layer being of a low friction polymer such as TFE or high density
polypropylene. Other suitable polymers for the delivery catheter 21
include polyurethane, polyvinylchloride, polyimide, polyamide and
the like. The delivery catheter 21 may also optionally have more
than one lumen, including a lumen for passage of a guidewire or
similar device.
[0033] FIG. 6 shows a graft 31 having features of the invention
deployed within a preselected portion 32 of a patient's body lumen
33. The preselected portion 32 of the patient's body lumen 33 has a
distended portion 34 that is representative of an aortic aneurysm
or the like. The body lumen 33 has a wall 35 that is engaged by the
graft 31. A second or inner-most thin wall graft member 36 is
disposed and deployed within a first thin wall graft member 37. A
first end 38 of the second thin wall graft member 36 is extending
longitudinally from a first end 41 of the first thin wall graft
member 37 to provide a smooth transition for a flow of blood
therethrough as indicated by arrow 39. Both the first and second
thin wall graft members 36 and 37 completely span the preselected
portion 32 of the patient's body lumen. The first end 41 of the
first thin wall graft member 37 and the first end 38 of the second
thin wall graft member are secured to a healthy tissue portion 42
of the body lumen 33. A second end 43 of the first thin wall graft
member 37 and a second end 44 of the second thin wall graft member
36 are also secured to a healthy tissue portion 42 of the body
lumen. Although the healthy tissue portion 42 of the patient's body
lumen 33 is shown as having a constant diameter in FIG. 6, the term
healthy tissue portion or is intended to mean any portion of a
patient's body lumen or passageway that has sufficient strength or
integrity to support an anchoring mechanism 12 and 13 of the type
discussed herein above.
[0034] FIG. 7 is an elevational view of a bifurcated embodiment of
a graft 50 having features of the invention shown in an expanded
deployed state. A second thin wall graft member 51 is disposed
within a first thin wall graft member 52. The first thin wall graft
member 51 and the second thin wall graft member 52 each have a
bifurcated configuration and each have a construction similar to
that of the of the thin wall graft of FIGS. 1-3.
[0035] FIG. 8 is a transverse cross sectional view of the graft 50
of FIG. 7 taken at lines 8-8 of FIG. 7. The first thin wall graft
member 52 is bifurcated and has a frame 53 and a membrane 54 within
the frame. The second thin wall graft member 51 is disposed within
the first thin wall graft member 52 and has a frame 55 and a
membrane 56 within the frame. The cross section of the first thin
wall member 52 and second thin wall member 51 is shown as round,
but is sufficiently flexible to assume a variety of shapes
necessary to engage an inside surface of a body lumen, including
irregularly shaped body lumens. In addition, although the graft 50
of FIG. 7 is shown with two thin wall graft members 51 and 52, any
suitable number of graft members could be used, so long as all
portions of the graft 50 which span a preselected length of the
patient's body lumen which is compromised have a sufficient number
of graft member layers and structural strength to maintain a flow
of blood therethrough and prevent leakage or failure of the
patient's body lumen. The thin wall graft members 51 and 52 of FIG.
7 are shown as complete bifurcated embodiments, however, they may
optionally be formed from multiple overlapping thin wall graft
members that are individually either partially bifurcated or not
bifurcated at all.
* * * * *