U.S. patent application number 09/942919 was filed with the patent office on 2002-08-29 for endoluminal prostheses and therapies for highly variable body lumens.
Invention is credited to Cox, Brian, Evans, Michael A., Freislinger, Kirsten, Kim, Steven W., Lenker, Jay A., Will, Allan.
Application Number | 20020120327 09/942919 |
Document ID | / |
Family ID | 26677991 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020120327 |
Kind Code |
A1 |
Cox, Brian ; et al. |
August 29, 2002 |
Endoluminal prostheses and therapies for highly variable body
lumens
Abstract
The present invention provides a branching endoluminal
prosthesis for use in branching body lumen systems which includes a
trunk lumen and first and second branch lumens. The prostheses
comprises a radially expandable tubular trunk portion having a
prosthetic trunk lumen, and radially expandable tubular first and
second branch portions with first and second prosthetic branch
lumens, respectively. A radially expandable tubular Y-connector
portion provides fluid communication between the prosthetic trunk
lumen and the first and second prosthetic branch lumens. Although
it is often considered desirable to maximize the column strength of
endoluminal prostheses, and although the trunk portion will
generally have a larger cross-section than much of the remainder of
a branching endoluminal prostheses, the expanded trunk portion is
more axially flexible than the expanded Y-connector portion, as
insufficient flexibility along the trunk portion may result in
leakage between the prosthesis and the trunk lumen of the body
lumen system. In contrast, the Y-connector portion benefits form a
less axially flexible structure to avoid distortion of the flow
balance between the luminal branches.
Inventors: |
Cox, Brian; (Cupertino,
CA) ; Evans, Michael A.; (Palo Alto, CA) ;
Will, Allan; (Atherton, CA) ; Lenker, Jay A.;
(Los Altos Hills, CA) ; Kim, Steven W.;
(Sunnyvale, CA) ; Freislinger, Kirsten; (Menlo
Park, CA) |
Correspondence
Address: |
STERNE, KESSLER, GOLDSTEIN & FOX PLLC
1100 NEW YORK AVENUE, N.W., SUITE 600
WASHINGTON
DC
20005-3934
US
|
Family ID: |
26677991 |
Appl. No.: |
09/942919 |
Filed: |
August 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09942919 |
Aug 31, 2001 |
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09121226 |
Jul 22, 1998 |
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6283991 |
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09121226 |
Jul 22, 1998 |
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08615697 |
Mar 13, 1996 |
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5824040 |
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60008254 |
Dec 1, 1995 |
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Current U.S.
Class: |
623/1.16 ;
623/1.11 |
Current CPC
Class: |
A61F 2220/0041 20130101;
A61F 2/885 20130101; A61F 2002/30199 20130101; A61F 2002/30327
20130101; A61F 2220/0075 20130101; A61L 27/34 20130101; A61F
2002/30604 20130101; A61F 2230/001 20130101; A61F 2002/048
20130101; A61F 2/92 20130101; A61F 2230/0063 20130101; C08L 67/00
20130101; A61F 2/91 20130101; A61F 2/95 20130101; C08L 67/00
20130101; A61F 2/915 20130101; A61F 2/90 20130101; A61F 2230/0095
20130101; A61F 2002/065 20130101; A61F 2250/006 20130101; A61L
31/10 20130101; A61F 2230/0067 20130101; A61F 2/958 20130101; A61F
2002/828 20130101; A61L 31/18 20130101; A61F 2002/047 20130101;
A61F 2/07 20130101; A61F 2220/0058 20130101; A61F 2250/0039
20130101; A61F 2/954 20130101; A61L 31/10 20130101; A61F 2002/075
20130101; A61L 27/34 20130101; A61F 2/89 20130101; A61F 2002/044
20130101; A61F 2002/041 20130101; A61F 2220/005 20130101; A61F
2002/046 20130101; A61F 2/88 20130101; A61F 2/848 20130101; A61F
2230/0054 20130101 |
Class at
Publication: |
623/1.16 ;
623/1.11 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. A branching endoluminal prosthesis for use in a branching body
lumen system which includes a trunk lumen and first and second
branch lumens, the prosthesis comprising; a radially expandable
tubular trunk portion having a prosthetic trunk lumen; radially
expandable tubular first and second branch portions with first and
second prosthetic branch lumens; and a radially expandable tubular
lumen separation portion which provides fluid communication between
the prosthetic trunk lumen and the first and second prosthetic
branch lumens; wherein the expanded trunk portion is more axially
flexible than the expanded lumen separation portion.
2. A branching endoluminal prosthesis as in claim 1, wherein the
prosthetic trunk lumen and the first and second prosthetic branch
lumens adjacent the lumen separation portion define a branch plane,
and wherein the trunk portion has greater axial flexibility roughly
perpendicular to the branch plane than the lumen separation
portion.
3. A branching endoluminal prosthesis as in claim 2, further
comprising a trunk sealing cuff on the trunk portion generally
opposite the lumen separation to seal between the prosthetic trunk
lumen and the trunk lumen of the body lumen system.
4. A branching endoluminal prosthesis as in claim 3, wherein the
trunk portion is more axially flexible than the trunk sealing
cuff.
5. A branching endoluminal prosthesis as in claim 1, wherein at
least a portion of the first and second branch portions are more
axially flexible than the lumen separation portion.
6. A branching endoluminal prosthesis as in claim 5, further
comprising branch sealing cuffs on the first and second branch
portions generally opposite the lumen separation to seal between
the prosthetic branch lumens and the branch lumens of the body
lumen system.
7. A branching endoluminal prosthesis as in claim 6, wherein the
branch portions are more axially flexible than the trunk sealing
cuffs.
8. A branching endoluminal prosthesis as in claim 1, wherein at
least one of the trunk portion and the first and second branch
portions comprises a liner supported by a helical coil defining a
plurality of separated loops to enhance axial flexibility, and
wherein the helical coil elongates during expansion of the liner to
avoid unwinding of the coil relative to the liner.
9. A branching endoluminal prosthesis for use in a branching body
lumen system which includes a trunk lumen and first and second
branch lumens, the prosthesis comprising; a radially expandable
tubular trunk portion having a prosthetic trunk lumen; radially
expandable tubular first and second branch portions with first and
second prosthetic branch lumens; a radially expandable tubular
lumen separation portion between the first and second branch
portions and the trunk portion to provide fluid communication
between the prosthetic trunk lumen and the first and second
prosthetic branch lumens; and sealing cuffs on the trunk portion
and the first and second branch portions generally opposite the
lumen separation to seal between the prosthetic lumens and the
lumens of the body lumen system; wherein the expanded branch
portions and trunk portion are more axially flexible than the
expanded lumen separation portion.
10. An endoluminal prosthesis comprising: a first prosthesis
portion including a first radially expandable frame which defines a
first axis, the first frame supporting a first tubular liner having
a first lumen; a second prosthesis portion including a second
radially expandable frame which defines a second axis, the second
frame supporting a second tubular liner having a second lumen; and
a flexible joint between the first and second prosthesis portions
to accommodate angles between the first and second axes, wherein
the flexible joint comprises a self supporting polymer tube having
integral ribs.
11. An endoluminal prosthesis as in claim 10, wherein the
self-supporting liner comprises a PTFE tube which extends between
the first and second liners.
12. An endoluminal prosthesis as in claim 10, wherein the first and
second frames comprise resilient structures.
13. An endoluminal prosthesis as in claim 10, wherein the first and
second portions have substantially higher column strength and hoop
strength than the flexible joint.
14. An endoluminal prosthesis comprising: a first prosthesis
portion including a first radially expandable frame which defines a
first axis, the first frame supporting a first tubular liner having
a first lumen; a second prosthesis portion including a second
radially expandable frame which defines a second axis, the second
frame supporting a second tubular liner having a second lumen; and
a flexible joint between the first and second prosthesis portions
to accommodate angles between the first and second axes, wherein
the flexible joint comprises a tubular joint liner supported by a
plurality of reinforcing elements, the reinforcing elements
comprising roughly cylindrical segments disposed axially along the
joint liner so as to slide relative to each other during radial
expansion.
15. An endoluminal prosthesis as in claim 14, wherein the
reinforcing elements comprise corrugated polyester.
16. An endoluminal prosthesis as in claim 14, wherein the
reinforcing elements comprise corrugated PTFE.
17. An endoluminal prosthesis as in claim 14, wherein the joint
liner comprises an expansible material.
18. An endoluminal prosthesis comprising: a plastically expansible
tubular liner having a lumen which defines an axis; and a helical
coil supporting the liner, the coil defining a plurality of loops,
wherein the loops are separated to enhance axial flexibility of the
prosthesis, and wherein the helical coil elongates during plastic
expansion of the liner to avoid unwinding of the coil relative to
the liner.
19. An endoluminal prosthesis as in claim 18, wherein the liner
comprises a polymer tube having integral ribbing disposed between
the separated loops of the coil.
20. An endoluminal prosthesis as claimed in claim 18, wherein the
coil is attached to the liner at a plurality of attachment points
along the length of the coil.
21. An endoluminal prosthesis as claimed in claim 17, wherein the
coil comprises linked diamond-shaped elements.
22. An endoluminal prosthesis as claimed in claim 17, wherein the
liner comprises partially oriented or unoriented polyester fiber,
the fiber being circumferentially oriented.
23. An endoluminal prosthesis as claimed in claim 18, wherein the
coil comprises a shape memory alloy or a shape memory polymer.
24. An endoluminal prosthesis for use in a bent body lumen, the
prosthesis comprising a radially expandable tubular frame defining
an axis, the frame including a plurality of resiliently expandable
loops and a plurality of plastically deformable connector elements
extending between adjacent loops which allow the axis to
plastically conform to the body lumen.
25. An endoluminal prosthesis as in claim 24, wherein the connector
elements plastically deform at a predetermined load which is
greater than physiological loads imposed on the deployed prosthesis
by the surrounding body lumen.
26. An endoluminal prosthesis as in claim 25, wherein the
predetermined load is less than or equal to loads imposed on the
prosthesis during deployment of the prosthesis within the body
lumen.
27. An endoluminal prosthesis as in claim 24, wherein the adjacent
loops are axially separated, and wherein the connector elements
comprise serpentine structures which extend axially between the
adjacent loops.
28. An endoluminal prosthesis as in claim 24, wherein the loops
comprise ring-frames.
29. An endoluminal prosthesis as in claim 28, further comprising a
tubular liner supported by the ring frames and the connector
elements.
30. An endoluminal prosthesis as in claim 24, wherein an attachment
mechanism allows a limited axial motion between at least some
connector elements and an associated loop without deforming the
connector elements.
31. A bifurcated endoluminal prosthesis for use within a branching
body lumen system having a trunk lumen and first and second branch
lumens, the trunk lumen having a larger cross-section than the
branch lumens, the trunk and branch lumens in fluid communication
at a lumenal intersection, the prosthesis comprising: a hub module
which is deployable within the body lumen system adjacent the
lumenal intersection; and a tubular trunk module having a first
port which sealingly engages the hub module when radially expanded
therein, an end opposing the first port which seals radially
against the surrounding trunk lumen opposite the hub module, and a
trunk lumen therebetween.
32. A bifurcated endoluminal prosthesis as in claim 31, wherein the
hub module includes a trunk lumen port in which the first port of
the trunk module is sealingly engageable, and first and second
branch lumen ports which are extendable into the first and second
branch lumens of the body lumen system so as to promote sealing
therewith.
33. A bifurcated endoluminal prosthesis as in claim 32, wherein a
portion of the hub between the trunk lumen port and at least one of
the first and second branch ports has enhanced axial
flexibility.
34. A bifurcated endoluminal prosthesis as in claim 32, further
comprising a radially expandable branch module having an end which
sealingly engages the deployed first branch port and extends along
the branch lumen of the body lumen system from the lumenal
intersection.
35. A bifurcated endoluminal prosthesis as in claim 31, wherein the
hub module comprises a molded tubular expandable body so that a
trunk port and branch ports substantially match the trunk lumen and
first and second branch lumens of a particular patient's body lumen
system.
36. A bifurcated endoluminal prosthesis for use within a branching
body lumen system having a trunk lumen and first and second branch
lumens, the trunk lumen having a larger cross-section than the
branch lumens, the trunk and branch lumens in fluid communication
at a lumenal intersection, the prosthesis comprising: a branch
module having a first branch end which is deployable within the
first branch of the body lumen system, a second branch end which is
extendable from the first branch end across the lumenal
intersection to the second branch of the body lumen system, a
prosthetic branch lumen therebetween, and a trunk port between the
first and second branch ends; and a tubular trunk module having a
first end which is sealingly engageable to the branch module, a
second end opposing the first end which seals radially against the
surrounding trunk lumen of the body lumen system, and a prosthetic
trunk lumen therebetween.
37. A bifurcated endoluminal prosthesis as claimed in claim 36,
wherein the first end of the trunk module sealingly engages the
trunk port of the branch module when deployed therein.
38. A bifurcated endoluminal prosthesis as claimed in claim 37,
wherein the branch and trunk modules engage so as provide a
predetermined flow split from the trunk module to the first and
second branch ends of the branch module.
39. A bifurcated endoluminal prosthesis as claimed in claim 36,
wherein the trunk lumen has a larger cross-section than the lumen
of the branch module adjacent the first or second branch ends.
40. A bifurcated endoluminal prosthesis for use within a branching
body lumen system having a trunk lumen and first and second branch
lumens, the trunk lumen having a larger cross-section than the
branch lumens, the trunk and branch lumens in fluid communication
at a lumenal intersection, the prosthesis comprising: a primary
module which is deployable within the body lumen system adjacent
the lumenal intersection; and a tubular trunk module having a first
port which is supported at least in part by the deployed primary
module when radially expanded therein, an end opposing the first
port which seals radially against the surrounding trunk lumen
opposite the primary module, and a trunk lumen therebetween.
41. A bifurcated endoluminal prosthesis as in claim 40, wherein the
primary module comprises a spacer having a trunk module support
surface and a branch engagement surface, and wherein the trunk
module support surface supports the expanded trunk module relative
to the branch engagement surface within the body lumen system.
42. A bifurcated endoluminal prosthesis as in claim 40, wherein the
primary module comprises a tapered body which tapers outward from a
first end to a second end opposite the trunk module, and further
comprising at least one branch module which expands radially to
engage a branch port adjacent the second end of the tapered
body.
43. A bifurcated endoluminal prosthesis as claimed in claim 40,
wherein the primary module comprises a radially expandable tubular
first branch module which supports the trunk module from within the
first branch lumen of the body lumen system, wherein the trunk
module comprises a bifurcated prosthetic module having a second
branch portion disposable adjacent the first port.
44. A bifurcated endoluminal prosthesis comprising: a radially
expandable trunk portion having a trunk lumen and a branch end;
radially expandable first and second branch portions extending from
the branch end of the trunk portion, the branch portions having
first and second branch lumens, the first and second branch lumens
being in fluid communication with the trunk lumen of the trunk
portion; wherein at least one of the branch portions is
compressible within the trunk portion, and wherein the at least one
branch portion is extendable from the expanded trunk portion in
situ.
45. A method for deploying an endoluminal prosthesis in a branching
body lumen system which includes a trunk lumen and first and second
branch lumens, the trunk lumen and branch lumens in fluid
communication at a lumenal intersection, the trunk lumen being
larger in cross-section than the first and second branch lumens,
the method comprising: deploying a primary module within the body
lumen system adjacent the lumenal intersection so that a trunk port
of the primary module extends along the trunk lumen; and expanding
a trunk module within the trunk lumen while an end of the trunk
module is within the trunk port of the primary module so that the
primary module engages and supports the trunk module from adjacent
the lumenal intersection.
46. A method as in claim 45, wherein the deploying step comprises
expanding a tubular hub module so that first and second branch
ports extend along the first and second branch lumens of the body
lumen system.
47. A methods as in claim 46, further comprising selecting a hub
module which approximately matches a geometry of a particular
patients branching body lumen system adjacent the lumenal
intersection.
48. A method as in claim 46, further comprising molding a hub
module to match a geometry of a particular patients branching body
lumen system adjacent the lumenal intersection.
49. A method as in claim 46, further comprising expanding a branch
module within the first branch port of the hub module.
50. A method for deploying an endoluminal prosthesis in a branching
body lumen system which includes a trunk lumen and first and second
branch lumens, the trunk lumen and branch lumens in fluid
communication at a lumenal intersection, the method comprising:
positioning a tubular prosthetic branch module across the lumenal
intersection from the first branch into the second branch, wherein
a common lumen port of the branch prosthesis module is adjacent to
the lumenal intersection; expanding the positioned branch module;
positioning a tubular common lumen module within the common lumen
of the body lumen system with at least one opening adjacent the
lumenal intersection; and expanding the positioned common lumen
module; wherein expansion of the later of the branch module and the
common lumen module sealingly engages the branch and common lumen
modules.
51. A method as in claim 50, further comprising inserting the
branch module through first and second openings of the expanded
common lumen module.
52. A method as in claim 50, further comprising inserting the
common lumen module into the common lumen port of the expanded
branch lumen module.
53. A method as in claim 50, wherein the common lumen comprises the
abdominal aorta, wherein the first and second branch lumens
comprise the left and right iliac arteries, and wherein the
sealingly engaged prosthetic modules extend upstream and downstream
beyond an aneurysm.
54. A method for deploying an endoluminal prosthesis in a branching
body lumen system of a patient, the branching lumen system
including first, second, and third lumens in fluid communication at
a lumenal intersection, the method comprising: positioning the
first wire through the lumenal intersection by introducing the
first wire in through the first lumen and out the second lumen;
threading a distal end of the first wire through a distal opening
of a second wire; and selectively tensioning proximal and distal
ends of the first wire and the proximal end of the second wire to
position the prosthesis adjacent to the intersection.
55. A method as in claim 54, further comprising: returning the
threaded first wire through the intersection and outside the
patient; and advancing the distal end of the second wire toward the
intersection by tensioning the proximal and distal ends of the
first wire.
56. A method as in claim 55, wherein the returning step comprises
advancing the threaded first wire back along the second lumen to
the intersection and out of the patient through the third
lumen.
57. A method for producing an endoluminal prosthesis comprising:
attaching an axially compressible elongate structure to an elongate
liner strip; coiling the liner strip to from a helix having a
plurality of loops; and attaching adjacent loops together so that
the liner defines a tube.
58. A sealing structure for sealing an end of a tubular endoluminal
prosthesis against a surrounding lumen, that sealing structure
comprising a plurality of flexible sealing flaps extending from the
prosthesis adjacent the end, the sealing flaps resiliently flaring
radially outward to independently seal against the surrounding
lumen.
59. An endoluminal prosthesis comprising: a tubular liner; and a
frame supporting the tubular liner, the frame defining a plurality
of loops having axially oriented apices, wherein at least some of
the adjacent apices of adjacent loops are offset to enhance axial
flexibility of the prosthesis.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 08/615,697, filed Mar. 13, 1996, which is a
continuation-in-part of provisional U.S. patent application Ser.
No. 60/008,254 (Attorney Docket No. 16380-003400), filed Dec. 1,
1995, the full disclosure of which is incorporate herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to tubular
prostheses, such as grafts, stents, stent-grafts, and the like.
More particularly, the present invention provides radially
expandable tubular prosthetic structures which are deployable
within tortuous body lumens, particularly within branching blood
vessels for the treatment of abdominal and other aneurysms.
[0004] Vascular aneurysms are the result of abnormal dilation of a
blood vessel, usually resulting from disease and/or genetic
predisposition, which can weaken the arterial wall and allow it to
expand. While aneurysms can occur in any blood vessel, most occur
in the aorta and peripheral arteries, with the majority of aortic
aneurysms occurring in the abdominal aorta, usually beginning below
the renal arteries and often extending into one or both of the
iliac arteries.
[0005] Aortic aneurysms are most commonly treated in open surgical
procedures, where the diseased vessel segment is bypassed and
repaired with an artificial vascular graft. While considered to be
an effective surgical technique, particularly considering the
alternative of a usually fatal ruptured abdominal aortic aneurysm,
conventional vascular graft surgery suffers from a number of
disadvantages. The surgical procedure is complex and requires
experienced surgeons and well equipped surgical facilities. Even
with the best surgeons and equipment, however, patients being
treated frequently are elderly and weakened from cardiovascular and
other diseases, reducing the number of eligible patients. Even for
eligible patients prior to rupture, conventional aneurysm repair
has a relatively high morality rate, usually from 2% to 10%.
Morbidity related to the conventional surgery includes myocardial
infarction, renal failure, impotence, paralysis, and other
conditions. Additionally, even with successful surgery, recovery
takes several weeks, and often requires a lengthy hospital
stay.
[0006] In order to overcome some or all of these drawbacks,
endovascular prosthesis placement for the treatment of aneurysms
has been proposed. Although very promising, many of the proposed
methods and apparatus suffer from undesirable limitations. In
particular, proper matching of an endovascular prosthesis with the
complex and highly variable vascular geometry can be
problematic.
[0007] Proper matching of the prosthesis to the proximal neck of
the aortic vessel and the branching blood vessels is critical to
the treatment of an aneurysm. The prosthesis preferably extends
axially beyond the weakened portion of the blood vessel to anchor
securely in the less diseased vessel wall. To prevent the leakage
of blood through a ruptured aneurysm, and also to prevent the
release of thrombus from within the distended aneurysm and into the
bloodstream, it is also preferable that the prosthetic lumen be
substantially sealed against the healthy endolithium. The
prosthetic lumen should remain open despite physiological movement
of the vasculature and environmental stresses, so as to promote the
free flow of blood. Furthermore, the geometry of the prosthetic
lumen at the luminal intersection where the abdominal aorta meets
the iliac arteries is of particular importance, as this bifurcation
can have a significant impact on the relative blood flows through
the two iliac arteries.
[0008] Unfortunately, the size, extent, and specific geometry of
abdominal aortic aneurysms can vary widely from patient to patient.
While the aneurysm is often downstream of the renal arteries, as
noted above, it may begin in very close proximity to these lateral
branching blood vessels, and in some cases will extend up to,
above, and along the renals themselves. Additionally, while the
aneurysm itself is typically a distension of the vessel wall, the
path the prosthesis must follow within the diseased vessel may be
fairly convoluted. For example, the abdominal aorta typically
defines a significant bend between the renal arteries and the iliac
arch when viewed from a lateral position. This aortic bend often
remains quite pronounced despite the presence of the distended
aneurysm, and complicates the sealing and anchoring of the
endoluminal prosthesis adjacent the renal arteries.
[0009] Abdominal aortic aneurysms also appear to have a significant
effect on the geometry of the intersection between the abdominal
aorta and iliac arteries. Even among healthy patients, there are
significant variations in the angles defined by the iliac arteries
relative to the aorta, typically being anywhere in the range
between 15-45.degree.. The variation in aorta iliac angularity is
often much wider in patients seeking therapy for aneurysms. In
fact, iliac arteries which branch off from an aorta with a local
angle of over 90.degree. have been found in aneurysm patients.
[0010] Known branching endoluminal prostheses are generally formed
as tubular, radially expandable stent-grafts. In contrast with the
convoluted branchings of diseased body lumens, these stent-graft
structures have typically been formed with simplistic cylindrical
frames or "stents." A separate liner or "graft" is typically
attached to the frame to prevent blood flow through a ruptured
vessel wall. Such liners are often formed from inelastic fabrics to
prevent pressure from distending a weakened luminal wall.
Typically, these branching structures are primarily supported from
immediately below the renal arteries. Patients may not be eligible
for these known endovascular aneurysm therapies if this portion of
the aorta is weakened by disease.
[0011] The branching stent-graft structures of the prior art have
generally comprised uniform structures, in which the smaller iliac
branch portions form cylinders which are substantially parallel to
the aortic portion when the prosthesis is at rest. Although these
straight branching prostheses are intended to deform somewhat to
accommodate the branch angles of body lumen systems, the imposition
of substantial axial bends on known endovascular stent-grafts tends
to cause folding, kinking, or wrinkling which occludes their lumens
and degrades their therapeutic value. Still another disadvantage of
known bifurcated stent-grafts is that even when they are flexed to
accommodate varying branch geometry, the prosthetic bifurcation
becomes distorted, creating an unbalanced flow to the branches. To
overcome these limitations, it has often been necessary to limit
these highly advantageous, minimally invasive endovascular
therapies to patients having vascular geometries and abdominal
aortic aneurysms which fall within very narrow guidelines.
[0012] For these reasons, it would be desirable to provide improved
endoluminal prostheses and methods for their use. It would further
be desirable to provide improved branching endoluminal prostheses,
and improved methods for placement of such prostheses. It would be
particularly desirable to provide endoluminal prostheses (and
methods for deploying them) which would accommodate widely varying
lumen system geometries, and which would thereby increase the
proportion of patients eligible to receive these highly
advantageous endoluminal prosthetic therapies for treatment of
abdominal aortic aneurysms and other disease conditions of the body
lumen systems.
[0013] 2. Description of the Background Art
[0014] Co-pending U.S. patent application Ser. No. 08/538,706
(Attorney-Docket No. 16380-003800), filed Oct. 3, 1995, the full
disclosure of which is hereby incorporated by reference, describes
modular prostheses and construction methods. Parent Provisional
Application (Attorney-Docket No. 16380-003400), previously
incorporated herein by reference, describes bifurcated modular
prosthetic structures and methods for assembling them in situ.
[0015] U.S. Pat. No. 5,064,435 describes a self-expanding
prosthesis which maintains a stable axial length during radial
expansion by anchoring of radial outward flares at each end, and by
sliding of an overlapping medial region therebetween. U.S. Pat. No.
5,211,658 describes a method and device for endovascular repair of
an aneurysm which makes use of separately introduced frame and
liner structures. A similar method of repairing blood vessels is
described in U.S. Pat. No. 5,078,726, in which a locking stent is
expanded within a vascular graft which has been positioned within
the blood vessel. The in situ deployment of an aortic intraluminal
prosthesis by a catheter having two inflatable balloons is
described in U.S. Pat. No. 5,219,355.
[0016] European patent application publication no. 0 551 179
describes a method for deploying two tubular grafts which extend in
parallel from the renals and into the aorta. U.S. Pat. No.
5,360,443 describes a bifurcated aortic graft which is secured to
the aorta by a plastically deformable frame positioned between the
renal arteries and the iliacs. Soviet Patent 145-921 describes a
bifurcated blood vessel prosthesis having a fastening element which
extends past the renal arteries to prevent migration. U.S. Pat. No.
4,774,949 describes a catheter having a lumen adapted to access
branch arteries.
[0017] U.S. patent application Nos. 4,550,447 and 4,647,416
describe vascular PTFE grafts which include transverse ribs
integral with a tube wall, and methods for their production. U.S.
patent application No. 5,443,499 describes a radially expandable
tubular prostheses for intraluminal implantation within children.
U.S. patent application Nos. 5,229,045 and 5,387,621 describe
porous membranes based on unstable polymer solutions which are
suitable for vascular prostheses, and methods for their
production.
SUMMARY OF THE INVENTION
[0018] In a first aspect, the present invention provides a
branching intraluminal prostheses for use in a branching body lumen
system that includes a trunk lumen and first and second branch
lumens. The prostheses comprises a radially expandable tubular
trunk portion having a prosthetic trunk lumen, and radially
expandable tubular first and second branch portions with first and
second prosthetic branch lumens, respectively. A radially
expandable tubular lumen separation portion provides fluid
communication between the prosthetic trunk lumen and the first and
second prosthetic branch lumens. Surprisingly, the expanded trunk
portion is preferably more axially flexible than the lumen
separation portion.
[0019] Although it is often considered desirable to maximize the
column strength of endoluminal prostheses, and although the trunk
portion will generally have a larger cross-section than much of the
remainder of a branching endoluminal prostheses, in connection with
the present invention it has been found that insufficient
flexibility along the trunk portion may result in leakage between a
bifurcated prosthesis and the trunk lumen of the body lumen system.
Specifically, leaks will be produced between known uniform
bifurcated prostheses and the dorsal bend which is typically found
immediately downstream of the renal arteries along the abdominal
aorta. On the other hand, the lumen separation portion benefits
from a less axially flexible structure to avoid distortion of the
flow balance between the luminal branches when conforming the
prosthetic geometry to a torturous body lumen system. The present
invention therefore provides non-uniform prosthetic structures
which are locally optimized to meet these contradictory
requirements.
[0020] Preferably, a trunk sealing cuff is provided opposite the
Y-connector to seal between the prosthetic trunk lumen and the
trunk lumen of the body lumen system. Similarly, the first and
second branch portions are also more axially flexible than the
lumen separation portion, and ideally include branch sealing cuffs
opposite the lumen separation. These sealing cuffs may also benefit
from relatively stiff structures, particularly where they help to
anchor the prosthesis within the body lumen. The resulting
prosthetic structure separates the luminal sealing, the axial
conforming, and the flow separating functions of the branching
prostheses to distinct axial portions of the prosthetic structure,
allowing these portions to be still further independently
optimized.
[0021] In another aspect, the present invention provides an
endoluminal prosthesis comprising first and second prosthesis
portions including first and second radially expandable frames
defining first and second axes, respectively. The frames support
tubular liners having lumens. A flexible joint between the first
and second prosthesis portions provides open fluid communication
between the first and second lumens when the first and second axes
are at an angle, the flexible joint comprising a self-supporting
liner which includes a polymer tube having integral ribs.
[0022] In yet another aspect, the present invention provides an
endoluminal prosthesis comprising a radially expandable tubular
liner having a lumen which defines an axis. A helical coil supports
the liner, the coil defining a plurality of loops which are
separated to enhance the axial flexibility of the prosthesis. The
helical coil elongates during expansion of the liner to avoid
unwinding of the coil relative to the liner. Hence, the coil may be
attached at a plurality of attachment points along the length of
the coil. Preferably, the coil comprises linked diamond shaped
elements, which may expand either resiliently or plastically during
deployment.
[0023] In yet another aspect, the present invention provides an
endoluminal prostheses for use in a body lumen, the prostheses
comprising a radially expandable tubular frame having an axis. The
frame includes a plurality of resiliently expandable loops, and
also includes a plurality of plastically deformable connector
elements extending between adjacent loops to allow the axis to
conform to the body lumen.
[0024] Preferably, the connector elements plastically deform at a
predetermined load which is greater than environmental forces
imposed on the expanded prostheses by the surrounding body lumen,
but which predetermined load is preferably less than or equal to
forces imposed on the prostheses during deployment. Ideally, the
adjacent loops of the frame are axially separated, and the
connector elements combine serpentine structures which extend
axially between the adjacent loops. It should be understood that
connector elements which yieldingly bend, and which remain bent
without resiliently straightening in situ will be "plastically
deformed" as used herein. Hence, shape memory alloys or polymers
which are deformed in situ such that they will not recover their
original shape at body temperatures will be "plastically deformed",
even if they would recover their shape if removed from the patient
body and heated beyond a transition temperature.
[0025] In some embodiments, at least some of the connector elements
are attached to an associated loop of the frame using axially
oriented slots, loosely tied sutures, or some other attachment
mechanism which allows a limited amount of axial motion without
deforming the connector member. Advantageously, such a structure
provides a self-expanding prostheses which conforms to a torturous
axial path of a body lumen without imposing resilient straightening
forces. This structure is therefore particularly well suited for
use in the flexible trunk or branch portions of the branching
prosthesis described above.
[0026] In yet another aspect, the present invention provides a
bifurcated endoluminal prosthesis for use within a branching body
lumen system having a trunk lumen and first and second branch
lumens. The trunk lumen will have a larger cross-section than the
branch lumens, and the trunk and branch lumens will be in fluid
communication at a luminal intersection. The prostheses comprises a
hub module which is deployable within the body lumen system
adjacent the lumenal intersection. A trunk module includes a first
port which sealingly engages the hub module when radially expanded
therein. An end opposing the first port seals radially against the
surrounding trunk lumen opposite the hub module. A prosthetic trunk
lumen is provided between the first port and the sealing end. Such
a structure is particularly advantageous when the trunk lumen of
the body lumen system has been weaken by disease adjacent to or
beyond the lumenal intersection, as the hub module facilitates
sealing at the bifurcation. Preferably, the hub module comprises a
tubal wall material which is at least partially self-supporting,
wherein a portion of the hub between the trunk lumen port and at
least one of the first and second branch ports has an enhanced
axial flexibility. Optionally, a radially expandable branch module
sealingly engages the deployed first branch port of the hub module,
and extends along the first branch lumen of the body lumen system
away from the luminal intersection. In certain patients, for
example, those having aorta iliac regions which are highly
distorted by an aneurism, it may be advantageous to form the hub
module as a custom molded tubular expandable body wherein the trunk
port and branch ports substantially match the trunk lumen in first
and second branch lumens of that particular patient's body lumen
system.
[0027] In yet another aspect, the present invention provides a
bifurcated endoluminal prosthesis for use within a branching body
lumen system having a trunk lumen and first and second branch
lumens. The trunk lumen will have a larger cross-section than the
branch lumens, and the trunk and branch lumens will be in fluid
communication at a luminal intersection. The prostheses comprises a
branch module having a first branch end which is expandable within
the first branch of the body lumen system, and also having a second
branch end which is expandable within the second branch of the body
lumen system, while a branch lumen extends therebetween. A trunk
port is located between the first and second branch ends, the trunk
port sealingly engageable with a first end of a tubular trunk
module. A second end of the trunk module seals radially against the
surrounding trunk lumen of the body lumen system. This branch
module is particularly advantageous for use in body lumen systems
having relatively sharp trunk/branch angles, particularly for
installation across the two iliac arteries in patients having
relatively advanced aortic aneurysms.
[0028] In yet another aspect, the present invention provides a
bifurcated endoluminal prosthesis for use within a branching body
lumen system having a trunk lumen and first and second branch
lumens. The trunk lumen will have a larger cross-section than the
branch lumens, and the trunk and branch lumens will be in fluid
communication at a luminal intersection. The prostheses comprises a
primary module deployable adjacent the lumenal intersection, and a
tubular trunk lumen which is supported at least in part by the
primary module when expanded therein. Advantageously, this
structure allows the prostheses to be supported for adjacent
healthy branch lumens, for example, allowing endovascular
prosthetic therapies for patient's who have relatively healthy
iliac arteries, but who do not have sufficiently healthy aortal
wall to substantially support a prostheses from between the renal
arteries and the iliacs. Alternatively, the primary module
comprises a tubular first branch module which supports the trunk
module from within the first branch lumen of the body lumen
system.
[0029] In yet another aspect, the present invention provides a
bifurcated endoluminal prostheses comprising a radially expandable
trunk portion having a trunk lumen and a branch end. Radially
expandable first and second branch portions extend from the branch
end of the trunk portion, with first and second branch lumens,
respectively. The first and second branch lumens are in fluid
communication with the trunk lumen of the trunk portion, and at
least one of the branch portions is compressible within the trunk
portion and extendible from the trunk portion when the prostheses
is positioned in situ. The at least one extendible branch portion
preferably comprises an evertable self-supporting or composite
structure. Alternatively, the at least one extendible branch
portion may slidingly engage the radially expandable trunk portion
so that it can telescope into the deployed position after the trunk
portion is positioned.
[0030] The present invention further provides a method for
deploying and endoluminal prostheses in a branching body lumen
system which includes a trunk lumen and first and second branch
lumens. The trunk and branch lumens are in fluid communication at a
luminal intersection, the trunk lumen being larger in cross-section
than the branch lumens. The method comprises deploying a primary
module within the body lumen system adjacent the luminal
intersection so that a trunk portion of the primary module extends
along the trunk lumen. A trunk module is then expanded within the
trunk lumen while an end of the trunk module is within the trunk
port of the primary module. Hence, the primary module engages and
supports the trunk module, rather than relying substantially
entirely on the trunk lumen of the body lumen system for
support.
[0031] In another aspect, the present invention provides a method
for deploying an endoluminal protheses in a branching body lumen
system which includes a trunk lumen and first and second branch
lumens which are in fluid communication at a luminal intersection.
The method comprises positioning a tubular prosthetic branch module
across the luminal intersection from the first branch into the
second branch so that a trunk port of the branch prostheses module
is adjacent to the luminal intersection. The positioned branch
module is expanded, and a tubular trunk module is positioned within
the trunk lumen of the body lumen system with at least one opening
adjacent the luminal intersection. The positioned trunk module is
expanded, wherein expansion of the ladder of the branch module and
the trunk module sealingly engages the branch and trunk modules
together.
[0032] In yet another aspect, the present invention provides a
method for deploying an endoluminal prothesis in a branching body
lumen system of a patient, the branching lumen system including
first, second and third lumens in fluid communication at a luminal
intersection. The method comprises positioning a first guide wire
through the luminal intersection by introducing the first wire in
through the first lumen and out the second lumen. A distal end of
the first wire is threaded through a distal opening of a second
guide wire. The prostheses may be positioned by selectively
tensioning proximal and distal ends of the first wire, and by
selectively tensioning the proximal end of the second wire.
Optionally, the threaded first wire is returned through the
intersection, and the distal end of the second wire is advanced
toward the intersection by tensioning the proximal and distal ends
of the first wire. Ideally, the first wire is returned back along
the second lumen to the intersection, and then out of the patient
through the third lumen, allowing the prosthesis to be precisely
positioned by tension from each of the three lumens at the luminal
intersection.
[0033] In yet another aspect, the present invention provides a
method for producing an endoluminal prosthesis comprising attaching
an axially compressible elongate structure to an elongate liver
strip and coiling the strip to form a helix having a plurality of
loops. The adjacent loops may conveniently be attached to form a
tube, thereby allowing continuous and automated production of large
numbers of coil-supported prostheses.
[0034] In a penultimate aspect, the present invention provides a
sealing structure for sealing an end of a tubular endoluminal
prosthesis against a plurality of flexible sealing flaps extending
from the prosthesis adjacent the end. The sealing flaps are
resiliently biased to flaps radially outward so as to independently
seal against the surrounding lumen.
[0035] In a final aspect, the present invention provides an
endoluminal prosthesis comprising a tubular liner and a frame
supporting the tubular liner. The frame defines a plurality of
loops having axially oriented apices, at least some of these
adjacent apices on adjacent loops being offset to enhance axial
flexibility of the prosthesis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a side view of an exemplary cylindrical vascular
stent-graft having axially constant characteristics.
[0037] FIG. 2 is a perspective view of an exemplary delivery
catheter for use with the prostheses of the present invention, with
a portion of the distal end broken away to disclose a prostheses
therein.
[0038] FIGS. 3A-3C illustrate a bifurcated endovascular prosthesis
having a relatively rigid expanded Y-connector portion, axially
flexible branch and trunk portions, and sealing/anchoring cuffs,
according to the principles of the present invention.
[0039] FIG. 4 illustrates a prostheses having two stent-graft
portions connected by a flexible joint comprising an integrally
ribbed polymer tube.
[0040] FIGS. 5A-5D illustrate an endoluminal prosthetic structure
in which a frame is supported by a helical coil of expansible
diamond shaped elements, for use in the flexible portions of the
prosthesis of FIGS. 3A-3C.
[0041] Fig. 5E illustrates a method for making an endoluminal
prosthesis having a helical coil by first attaching the coil
material to a strip of liner material, winding the liner strip over
a mandrel, and sewing the strip in a helical shape.
[0042] FIGS. 5F-5H illustrates alternative stent-graft sealing
structures, according to the principles of the present
invention.
[0043] FIGS. 6A-6C illustrate alternative flexible prosthetic
structures in which the liner is supported by a plurality of
cylindrical segments.
[0044] FIG. 7A illustrates an endoluminal prosthetic structure in
which a liner is supported by a plurality of self-expanding loops,
and in which serpentine malleable connectors extend between
adjacent loops, according to the principles of the present
invention.
[0045] FIGS. 7B-7G show alternative connector structures and
connector attachment mechanisms for use in the prosthesis of FIG.
7A.
[0046] FIGS. 8A-8F illustrate a method for deploying a
self-supporting endoluminal hub module within a luminal
intersection, according to the principles of the present
invention.
[0047] FIGS. 9A-9B illustrate alternative endoluminal hub modules
having flexible portions between their trunk and branch
portions.
[0048] FIGS. 10A-10C illustrate a method for positioning guide
wires adjacent to a luminal intersection to promote precise
positioning of an endoluminal prostheses by selectively tensioning
opposed guide wire ends, according to the principles of the present
invention.
[0049] Figs. 11A-11C illustrate a method for deploying a branching
endoluminal prostheses by first deploying a branch module which
extends across the trunk lumen and extending into opposing branch
lumens, and by then deploying a trunk module within a trunk port of
the branch module, according to the principles of the present
invention.
[0050] FIG. 12 illustrates an alternative branching endoluminal
prostheses in which a branch module is positioned through a
deployed trunk module, according to the principles of the present
invention.
[0051] FIG. 13 illustrates an alternative branching inner luminal
prostheses in which independent branch modules are deployed within
an expanded trunk module.
[0052] FIGS. 14A-14B illustrate a method for deploying a branching
endoluminal prostheses in which a spacer module is first deployed
to provide support for the trunk module from adjacent to the branch
lumens of the body lumen system.
[0053] FIGS. 15A-15B illustrate a method for deploying a branching
prostheses in which a tapering primary module is first deployed
adjacent a luminal intersection, according to the principles of the
present invention.
[0054] FIGS. 16A-16B illustrate a still further alternative method
for deploying a branching endoluminal prostheses in which the trunk
module is deployed within and supported by a previously deployed
branch module, according to the principles of the present
invention.
[0055] FIGS. 17A-17D illustrate an alternative branching
endoluminal prostheses in which at least one branch portion is
compressed within the trunk portion during positioning and
deployment.
[0056] FIGS. 18A-18B illustrate alternative branching endoluminal
prosthetic structures having reduced compressed frame volumes and
adjustable branch lengths, according to the principles of the
present invention.
[0057] FIG. 19 illustrates a branching endoluminal prosthesis
having a short trunk portion to increase overall axial flexibility,
according to the principles of the present invention.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0058] The present invention provides radially expansible tubular
prostheses, particularly grafts, stents, and stent-grafts, which
are highly adaptable to varying luminal system geometries. The
prostheses of the present invention are suitable for a wide variety
of therapeutic uses, including stenting of the ureter, urethra,
trachea, branchi, esophagus, biliary tract, and the like. The
present devices and methods will also be useful for the creating of
temporary or long term lumens, such as the formation of
fistulas.
[0059] The prosthetic structures of the present invention will find
their most immediate use as endovascular prostheses for the
treatment of diseases of the vasculature, particularly aneurysms,
stenoses, and the like, and are especially well suited to the
distorted aortal/iliac junction of persons having advanced vascular
diseases. These prostheses will generally be radially expansible
from a narrow diameter configuration to facilitate introduction
into the body lumen, typically during surgical cutdown or
percutaneous introduction procedures.
[0060] The prosthetic structures described hereinbelow will find
use in axially uniform cylindrical prostheses, in preassembled
bifurcated prostheses, and as prosthetic modules which are suitable
for selective assembly either prior to deployment, or in situ. Such
selective assembly of prosthetic modules to form a customized
endoluminal prosthesis is more fully described in co-pending U.S.
patent application Ser. Nos. 60/008,254 and 08/538,706 (Attorney
Docket Nos. 16380-34 and 16380-38) the full disclosures of which
have previously been incorporated herein by reference.
[0061] An exemplary cylindrical graft structure 10 is illustrated
in FIG. 1. Prostheses 10 comprises a perforate tubular frame 12
which includes a plurality of independent (non-connected) ring
frames 14. The tubular frame 12 supports an inner frame 18.
Optionally, an outer liner is disposed over the ring frames, either
inside of inner liner 18, or in combination therewith.
[0062] To secure ring frames 14 in place, and to secure the liner
to the perforate tubular frame 12, the liner is typically sutured
to the frame. A wide variety of alternative liner/frame attachment
mechanisms are available, including adhesive bonding, heat welding,
ultrasonic welding, and the like. Where inner and outer liners are
used, the ring frames may be sandwiched between the liners and held
in place by attaching the liners to each other.
[0063] The prostheses 10 will typically have a length in the range
from about 20 mm to 500 mm, preferably from 50 mm to 200 mm, with a
relaxed diameter in the range from about 4 mm to 45 mm, preferably
being in the range from about 5 mm to 38 mm. Alternative
stent-graft structures are more fully described in U.S. application
Ser. No. 08/538,706 (Attorney Docket No. 16380-38), previously
incorporated by reference.
[0064] Referring now to FIG. 2, an exemplary delivery catheter 30
for use with the endoluminal prostheses of the present invention
comprises a tubular cover 32 and a shaft 34. Cover 32 has a central
lumen 36 extending from a proximal end 38 to a distal end 40. Shaft
34 is slidably received within central lumen 36 and extends
proximally of cover 32. A plurality of runners 42 extend distally
from shaft 34. Runners 42 line a portion of the inner surface of
lumen 36, and slide within the lumen of the shaft. Shaft 34 also
has a lumen, in which a core shaft 44 is slidably disposed. Core
shaft 44 has a guide wire lumen 46. Nosecone 48 is fixed to the
distal end of core shaft 44, and can therefore be manipulated
independently of runners 42.
[0065] Prostheses 10 is radially compressed and restrained within
the plurality of runners 42. In turn, cover 32 prevents runners 42
from expanding outward. Runners 42 are formed from a hard material,
and distribute the expansion load of prostheses 10 over the inner
surface of central lumen 36. The deploying force is applied
proximally against a slider 50 attached to a distal end 38 of cover
30, while holding a luer fitting 52 at the distal end of shaft 34,
thereby withdrawing the cover proximally from over the prostheses.
An additional luer adapter 54 at the distal end of core shaft 44
allows the core shaft to be manipulated independently, and to be
releasibly secured to the shaft 34. Exemplary methods and devices
for placement of the prostheses of the present invention are more
fully described in co-pending U.S. patent application Ser. No.
08/475,200, filed Jun. 7, 1995 (Attorney Docket No. 16380-001130),
the full disclosure of which is incorporated herein by
reference.
[0066] Referring now to FIGS. 3A-3C, an exemplary branching
endovascular protheses 60 comprises a lumen separation portion 62
between a trunk portion 64 and two branch portions 68. Lumen
separation portion 62 preferably comprises a relatively rigid
structure, having higher column and hoop strength than the
remainder of the prostheses.
[0067] In this exemplary embodiment, the lumen separation portion
comprises a flexible liner supported by a resiliently expanding
frame. The cross-section of the frame adjacent the branches
includes discrete lobes which correspond to the first and second
branches, and also includes an isthmus therebetween to help prevent
an imbalance of flow from the trunk portion to the branch portions.
Such a lumen separation portion is more fully described in parent
application (Attorney Docket No. 16380-003400), also previously
incorporated by reference. Ideally, the perforate frame of lumen
separation portion 62 is continuous along its axial length,
increasing the column strength of the lumen separation so that the
flow separation geometry of the branching inner lumen remains
constant regardless of the flexing of the trunk and/or branch
portions.
[0068] The advantageous flexibility of branch portions 68 is shown
most clearly in FIG. 3B, in which prostheses 60 is shown deployed
within an abdominal aorta A downstream of the renal arteries RA,
extending beyond an abdominal aortic aneurism AA, and into the
right and left iliac arteries RI, LI. Branch portions 68 have
relatively high axial flexibility to accommodate the extreme angles
between the iliac and abdominal arteries which have been found in
patients having such aneurysms.
[0069] Trunk sealing cuff 66 and branch sealing cuffs 70 securely
anchor the prostheses against the healthy tissue beyond the
aneurism, and also seal the prosthetic lumen against the
surrounding endolithium of the body lumen system. Trunk sealing
cuff 66 will often comprise a polyester such as Dacron.TM.,
preferably in an expansible form, ideally as a fabric woven with
partially oriented or unoriented polyester fibers in the fill or
weave. Alternatively, polyester (or some other fiber) which has
been wrapped around a core fiber to allow expansion may be used, or
the sealing cuff may comprise a PTFE, silicone, or polyurethane
foam to promote sealing between the prosthetic lumen and the
surrounding body lumen. Exemplary sealing cuff structures are more
fully described in co-pending U.S. patent application Ser. Nos.
08/525,989 and 08/538,706, filed Oct. 3, 1995, and Sep. 8, 1995
(Attorney Docket Nos. 16380-30 and -38), the full disclosures of
which are incorporated herein by reference.
[0070] One particular advantage of the axial flexibility of trunk
portion 64 can be understood with reference to the lateral view of
the abdominal aorta illustrated in FIG. 3C. Although the aneurysm
AA generally distends the abdominal aorta, the specific shape and
extent of the aneurysm can vary widely. Even when healthy, the
abdominal aorta often angles dorsally just downstream of the renal
arteries. The presence of this bend B often persists despite the
general distension of the abdominal aorta.
[0071] Advantageously, flexible trunk portion 64 allows the trunk
sealing cuff 66 to anchor securely along the axis of the healthy
abdominal aorta adjacent the renal arteries, and greatly helps to
reduce perimeter leaks around the upstream end of the trunk
portion. Those of skill in the art will understand that the trunk
portion would tend to have a relatively high rigidity and column
strength, due to its relatively large cross-section (which must
accommodate the combined flow for both iliac arteries). It should
also be understood that the flexible trunk and leg portions will
preferably maintain sufficient hoop strength so that their
respective lumens remain open throughout a wide range of branch
positions, and despite normal physiological movement and
environmental stress from the surrounding body lumen. Hence, the
flexible trunk and leg portions will preferable comprise a coiled
prosthetic structure or a radially expandable, axially malleable
structure as described hereinbelow. Alternatively, the flexible
trunk and branch portions may comprise an unsupported (or
self-supporting) liner.
[0072] Referring now to FIG. 4, a jointed prosthesis structure 72
provides axial flexibility and kink resistance, and may therefore
find use in the flexible sections of exemplary branching
endoluminal prosthesis 60 (see FIG. 3A). Jointed prosthesis 72
includes a plurality of stent-graft portions 74 with a joint
portion 76 therebetween. Stent-graft portions 74 comprise a liner
80 supported by a perforate radially expandable frame 78.
Preferably, joint portion 76 comprises an integrally ribbed polymer
tube, as taught by U.S. Pat. Nos. 4,647,416 and 4,550,447, the full
disclosures of which are incorporated herein by reference. Ideally,
the joint comprises a ribbed PTFE tube which extends continuously
to form the liners of the stent-graft portions.
[0073] Advantageously, the framed structure of the stent-graft
portion provides the column and hoop strength to support the inner
lumen, while the self-supporting joint structure allows the jointed
prosthesis to easily adapt to tortuous body lumens. It may be
advantageous to provide a series of such liner will preferably
include ribs 92 disposed between the adjacent loops 90 of
expandable coil 84.
[0074] A method of fabricating a helical stent-graft 71 will be
described with reference to FIG. 5E. A series of linked
diamond-shaped elements 73 are first attached to a strip of liner
material 75, typically being stitched with a sewing machine. The
ribbon is then wound over a mandrel 77 of the desired size, and
adjacent edges of the ribbon are sewn to each other (or otherwise
permanently joined). Such a method may be substantially automated
and continuous, and is thus particularly beneficial for producing a
large number of prostheses. The helical stent-graft may optionally
be cut to length, but will preferably include a crown stitched
stent-ring 79 for sealing and ends against a surrounding lumen when
deployed therein.
[0075] A novel feature of helical stent-graft 71 which will have
application in a wide range of stent-graft structures is the
offsetting of apices 69. Diamond-shaped elements 73 define axially
oriented apices 69 at regular intervals along the loops. Through
proper sizing of mandrel 77 and monitoring of the loop sewing
process, the adjacent apices may optionally be offset from the
adjacent apices, each apex ideally being roughly equally spaced
from the two adjacent apices as shown. Advantageously, this
increases axial flexibility by allowing the liner to flex between
loops but without substantially decreasing hoop strength.
Conveniently, the column strength may be selectively and locally
increased (and axial flexibility correspondingly decreased) by
adjusting the winding of ribbon 75 so that the adjacent apices are
substantially aligned. In fact, aligned apices may be selectively
attached to each other, for example, with a lock stitch pattern (as
shown in FIG. 5, 4, and more fully explained in co-pending U.S.
patent application Ser. No. 08/538,706, filed Oct. 3, 1995
(Attorney Docket No. 16380-003800), previously incorporated herein
by reference), to greatly reduce axial flexibility where desired.
Clearly such selective offsetting of apices will be effective with
ring frames, zig-zag coils, and a wide range of alternative
stent-graft structures, and continuous graft configurations.
[0076] Alternative sealing structures are illustrated in FIGS.
5F-G. Generally, liner 81 is split at one end to form a plurality
of sealing flaps 83. Optionally, the sealing flaps are
substantially unsupported by the frame. Alternatively, the frame
adjacent sealing flaps 83 includes axially elongate members which
support the sealing flaps, for example, elongate diamonds 85 or
fingers 87. These elongate member (or the sealing flaps themselves)
are preferably resiliently biased radially outward, typically by
heat setting over a tapered mandrel. In some embodiments, the flaps
may fold back along the prosthesis when the prosthesis is
compressed for deployment. Regardless, each sealing flap will
preferably expand radially outward substantially independently of
the other sealing flaps, thereby improving the seal between the end
of the prosthesis and a highly irregular body lumen. Optionally
more than one row of overlapping sealing flaps may also be
used.
[0077] Referring now to FIGS. 6A and B, an alternative flexible
prosthetic structure may be fabricated by cutting a cylindrical
corrugated polyester graft 96 into a series of cylindrical
segments. The cylindrical segments may then be used as reinforcing
elements by attaching them axially along an expansible tube 100.
Suitable expansible tubes may be formed from partially oriented
yarn, polypropylene, polyethylene, annealed polyester, PTFE, or the
like. The reinforcing elements are preferably free to slide over
each other as the liner is expanded in situ, and provide some
column strength, hoop strength, and kink resistance while also
allowing the reinforced lumen to flex axially.
[0078] Optionally, a plurality of expansible fibers or yarns 102
could be wrapped around the exterior of the corrugated graft
segments to hold the structure in a compact profile, and yet still
allow expansion. Alternatively, outer fibers 102 may be frangible,
breaking under a predetermined force to allow the prosthesis to be
expanded in situ to the desired size. An internally supported
flexible structure 104 having similar internal reinforcing elements
106 may optionally avoid the use of the external wrapping
yarns.
[0079] A particularly advantageous flexible prosthetic structure
110 will be described with reference FIGS. 7A-G. Flexible structure
110 comprises a radially expandable liner 112 supported by a
plurality of ring frames 114. A series of connector elements 116
extend between adjacent ring frames 114. Optionally, connector
elements 116 may also be used to support the liner 112.
Advantageously, the connector elements and ring frames may be
independently optimized to tailor the mechanical properties of the
prosthesis structure, particularly for use as a flexible trunk or
branch position in the branching prosthesis of FIG. 3A.
Alternatively, flexible prosthetic structure 110 may find use as a
stent, or as a cylindrical stent-graft.
[0080] Preferably, the ring frames comprise resilient
self-expanding structures, ideally comprising a super-elastic shape
memory alloy such as Nitinol.TM.. Connectors 116 preferably
comprise a malleable material, ideally including martensitic
Nitinol.TM., stainless steel, cobalt-nickel alloy, titanium, or
tantalum. Clearly, the connector elements can provide additional
column strength to the prosthetic structure, as well as providing
support to the liner between the ring frames. Advantageously, such
malleable connectors may also provide a structure which will expand
resiliently when deployed in situ, and which will conform
plastically to an axially tortuous body lumen, such as the blood
vessels of the vascular system.
[0081] Preferably, connector elements 116 comprise serpentine
elements which extend axially between adjacent frame loops. Careful
selection of the serpentine shape allows tailoring of the bending
properties of the prosthesis. Such serpentine connector elements
located at the outer portion of an axial bend in the prosthesis
will be straightened, while those at the inner portion will
decrease in length, optionally maintaining the axial length of the
prosthesis at a relatively constant amount. Alternatively, the
connector elements may rely primarily (or solely) on either
elongation or compression alone, thereby inducing changes in the
length of the prosthesis when bent.
[0082] FIGS. 7B-D illustrate alternative connector element
structures. A flat connector element 118 may be cut from a flat
sheet of the desired malleable material, and optionally includes
ends 120 having passages cut therethrough to facilitate attachment
of the connector element to the resilient frame structure. Such a
flat structure has the advantage of not decreasing the internal
prosthetic lumen cross-section within a narrow body lumen, and the
flat serpentine shapes may be cut from sheet stock using known
laser cutting, lithography techniques, or the like.
[0083] Alternatively, a wire connector element 122 having bent loop
ends 124 may be formed as a helical coil. In a still further
alternative, a bent connector element 126 may be formed from a
straight strip of malleable material, as shown in FIG. 7D, and may
also include folded ends 128. Clearly, a wide variety of
alternative metallic or polymer connector structures may be
suitable. Generally, it will be preferable to make use of materials
which are both malleable and biocompatible, as described above.
[0084] A variety of alternative attachment mechanisms for coupling
the frame structure to the connector elements are shown in FIGS.
7E-G, and also in FIG. 7A. Generally, the connector elements may be
attached to the frame loops by welding, soldering, adhesive
bonding, polymer rivets, suturing, or the like. In some
embodiments, it may be possible to utilize members which extend
from a resilient frame, and which have been formed to the desired
shape and heat treated or otherwise processed to produce the
desired malleable properties. In some embodiments, the mechanism
used to attach the resilient frame to the connector elements will
also attach the liner to the frame, for example, stitching which
extends through passages in both the connector elements and the
frame, and then through a woven textile liner.
[0085] It may be desirable to allow some longitudinal motion
between the connector elements and their associated frames without
deforming the connector elements. An oversized suture loop 130
between a ring frame 14 and passage 120 of flat connector element
118 provides a limited amount of axial motion. Similarly, an axial
slot 134 in a slotted frame 132 provides a precisely controlled
amount of axial motion of a loop 136 on a wire connector element
138. Note that loop 136 may further be reinforced by suture, wire,
adhesive, or the like. Alternatively, the end of the connector
element may be folded over a ring frame 14, and optionally
adhesively bonded in place, to provide a positive connection.
[0086] Preferably, connectors 116 compress or elongate plastically
under forces typical of those imposed on the prosthesis during
deployment. As these forces are typically higher than normal
physiological forces, the connector elements may advantageously be
constructed to avoid deformation from these normal blood and tissue
in vivo forces, particularly where a limited amount of axial motion
is allowed between connector elements and the ring frames.
Therefore, the prosthesis structure can plastically deform during
deployment to conform the axis of the prosthesis with the
surrounding body lumen, but will thereafter avoid imposing
resilient straightening forces against the body lumen.
[0087] A method for assembling in situ an endoluminal prosthesis by
first positioning and deploying a hub module will be described with
reference to FIGS. 8A-E. A branch access catheter 140 is used to
insert guidewires 142 down the aorta A and into the left iliac LI
and right iliac RI. The branch access catheter 140 preferably
comprises a deflecting tip branch access catheter as taught by U.S.
Pat. No. 4,774,949, the full disclosure of which is incorporated
herein by reference.
[0088] A resilient hub module 144 is advanced over both guidewires
142 while compressed within delivery sheath 146. Hub module 144
preferably comprise an elastic sponge-like microporous silicone,
silicone foam, low purometer silicone, polyurethane foam or the
like, as more fully described in co-pending U.S. patent application
Ser. No. 08/525,989, filed Sep. 8, 1995, (Attorney-Docket No.
16380-003000) the full disclosure of which is incorporated herein
by reference. Hub module 144, which may be stented or unstented, is
deployed over guidewires 142 at the luminal intersection I of the
aorta A and left and right iliacs LI, RI, optionally extending
along the iliacs beyond the aortic aneurysm AA. Ideally, hub module
144 is deployed by a combination of distally advancing pusher shaft
148 and proximally withdrawing catheter sheath 146 so that a trunk
portion 150 of the hub module remains within the aorta, while
branch portions 152 extend into each of the iliacs. The hub module
wall material will preferably be at least in part self-supporting,
but may be reinforced adjacent the trunk or branch ports for
sealing and to provide sufficient hoop strength to allow prosthetic
modules to sealingly engage the hub from within.
[0089] In some embodiments, it may be possible to completely seal
off aortic aneurysm AA by positioning a trunk module 154 within
trunk port 150 and expanding the trunk module to sealingly engage
the hub module and the healthy aorta upstream of the aneurysm, as
illustrated in FIG. 8E. In other cases, it may be necessary to
extend one or more branch modules 156 along one or both iliac
arteries to fully bypass the aneurysm, as illustrated in FIG. 8F. A
four branch hub module 158, similar in structure to hub module 144,
may find use in sealing off the upper end of an aneurysm which
extends to or along the renal arteries, optionally making use of a
renal branch module 160 similar to branch module 156 described
above. optionally, one or more hubs may be securely attached to
(and deployed with) a trunk stent-graft.
[0090] Although the exemplary microporous silicone can adapt to a
range of luminal intersection geometries, it may be advantageous to
provide a variety of hub modules having differing angles to
accommodate a wider variety of vascular geometries, allowing
selection of a suitable hub for each patient. In extreme cases, it
may even be preferable to custom mold a hub module for a specific
patient's vasculature, preferably based on information provided by
fluoroscopy, ultrasound, or some other imaging modality.
[0091] To increase the ability of the hub module to conform to a
variety of vascular geometries, it may be advantageous to include
corrugated portions 162 or braided portions 164 between the trunk
port 150 and the branch ports 152 as illustrated in FIGS. 9A-D.
Such corrugated structures accommodate compression along the inside
of a tight bend radius without kinking, while braided structures
are inherently kink resistant when bent. Similar enhanced
flexibility portions may be used at the junctions of a trifurcation
to increase the conformability of an aortal renal hub module,
similar to renal hub module 158 shown in FIG. 8F. Advantageously,
first deploying the hub module adjacent the intersection of the
aorta and iliac arteries allows the trunk module to be supported at
least in part from the luminal intersection, particularly during
deployment.
[0092] A method for precisely positioning an endoluminal prosthesis
using guidewires which pass through the luminal intersection will
be described with reference FIGS. 10A-C. In the exemplary method, a
guidewire 166 is introduced from an inferior position and advanced
along the right iliac, RI beyond the luminal intersection I,
through the aorta A to the subclavian-or carotid artery, where the
guidewire is extended out of the patient body. Guidewire 166 can
then be threaded through a loop 168 in a second guidewire 170, and
the distal end of guidewire 166 be again maneuvered back through
the aorta, beyond the luminal intersection I, along one of the
iliac arteries, and again extended out of the patient body.
[0093] Advantageously, a proximal end 172 and distal end 174 of
guidewire 166 may be selectively tensioned to advance second
guidewire 170 down the aorta to the luminal intersection I.
Optionally, guidewire 166 may be fed inward and outward through the
same iliac to allow loop 168 to be positioned relative to the
aortic and one of the two iliac arteries. Alternatively, as shown
in FIG. 10C, guidewire 166 may be fed inward through, and outward
from, alternative iliac arteries. In either case, tensioning the
proximal and distal ends of guidewire 166 and the proximal end of
second guidewire 170 precisely positions hoop 168 relative to the
luminal intersection I. Hence, this method provides multiple points
of control and access to fine tune endoluminal prosthesis
placement, and allows prosthetic modules to be advanced along
either end of guidewire 166 or along second guidewire 170 to the
precisely positioned loop 168.
[0094] As described above, many bifurcated stent-graft systems
depend on attachment to a narrow healthy or less diseased zone
between the renal arteries and the upstream end of the aneurysm.
The length and diameter of this healthy zone can be very difficult
to predict, making secure attachment and sealing of the endoluminal
prosthesis problematic. As there may be little or no healthy aorta
remaining between the aneurysm and the renal arteries to anchor a
branching endoluminal prosthesis, it would be advantageous to find
alternative support mechanism for branching endoluminal
prostheses.
[0095] As was also described above, the iliac arteries may define
substantial angles relative to the aorta, particularly on patients
having abdominal aortic aneurysms. This often complicates the
positioning of a tightly compressed (and therefore relatively
stiff) endoluminal prosthesis across the lumenal intersection from
the aorta to the iliac arteries.
[0096] For these reasons, it may be advantageous to instead
position and deploy a branch module 176 extending across the
luminal intersection I from the right iliac to the left iliac, as
illustrated in Fig. 11A. Branch module 176 will generally include a
trunk port 180 which is preferably oriented along the aorta, as
shown in Fig. 11B. Such orientating of prosthetic modules is aided
by a radiographic marker 178 which provide a visual representation
of the expanded module under imaging. Optionally, a balloon
catheter 182 may be used to hold branch module 176 in position
during deployment of a trunk module 184 into sealing engagement
with trunk port 180.
[0097] Referring now to FIG. 12, branch module 176 may
alternatively be deployed through branch ports 186 of a previously
deployed primary trunk module 188. Flow for the two iliacs thus
enters the branch module within the lumen of primary trunk module
188 through trunk port 180. A somewhat similar arrangement, which
makes use of independent branch modules 190 that sealingly engage
an alternative primary trunk module 192 at branch ports 186, is
illustrated in FIG. 13.
[0098] It would be advantageous to provide still further
alternative methods for supporting the endoluminal prosthesis
assembly, rather than relying substantially on the aorta below the
renals. As illustrated in FIGS. 14A-B, a spacer module 192 may
first be deployed adjacent the luminal intersection I, preferably
with a lower surface 196 in contact with the bifurcation B of the
body lumen system. Spacer module 192 is selected so that an upper
surface 198 is at the proper distance from the lower surface 196 so
that a bifurcated trunk module 194 resting on upper surface 198 is
correctly positioned just downstream of the renal arteries. Branch
modules may then be positioned through the spacer module and into
the branch ports of the bifurcated trunk module to complete the
bifurcated prosthesis assembly. Clearly, one or more of the branch
portions may optionally be formed integrally with the trunk
portion, within the scope of the present invention.
[0099] A still further alternative modular prosthetic assembly will
be described with reference to FIGS. 15A-B. Tapered primary module
202 includes a wide branch end 204 which is optionally deployed
within the luminal intersection so as to be supported by the body
lumen bifurcation B. Advantageously, the wide branch end 204
facilitates engaging branch modules 208 from widely divergent iliac
arteries, and may also help support a trunk lumen sealing module
206 from the bifurcation of the body lumen, as shown in FIG.
15B.
[0100] The present invention also provides supporting in situ
endoluminal prosthesis assembly from within the iliac, as
illustrated in FIGS. 16A-B. In this embodiment, a branch prosthetic
module 210 is first deployed within a relatively healthy renal
artery. One branch port 212 of a bifurcated prosthetic module 214
is then positioned and expanded within branch module 210.
Optionally, a second branch module is then positioned within an
alternate branch port of the bifurcated modules 214, completing the
in situ assembly of the bifurcated prosthesis system.
[0101] It would be desirable to reduce the number of prosthetic
module deployment steps required to deploy an endovascular
bifurcated prosthesis system. Toward that end, as shown in FIGS.
17A-D, an extendable leg bifurcated prosthesis 216 may have one or
more leg portions 218 disposed within the trunk portion 220 when
the prosthesis is radially compressed for positioning and
deployment. Optionally, the leg may be everted within the trunk
portion, the leg preferably comprising a self-supporting or
composite material. Alternatively, the leg may slidingly engage the
trunk portion and telescope out into position. In either case,
disposing the leg within the trunk portion greatly facilitates
positioning the prosthesis across the luminal intersection I.
[0102] The location and extent of aneurysms along the renal
arteries varies considerably between patients, and may at times be
difficult to accurately measure. It would therefore be advantageous
to provide modular structures adaptable to a wide range of iliac
leg positions. The prosthetic assemblies of FIGS. 18A-B achieve
such iliac leg placement flexibility by extending a relatively
rigid iliac module through bifurcation modules 232, 234, optionally
even allowing iliac module 230 to extend in cantilever beyond renal
arteries RA. Additionally, by minimizing the length of the trunk
lumen portion of the prosthesis, the mass of each module is
minimized, facilitating intravascular maneuvering.
[0103] To provide some mutual support between the parallel iliac
portions, bifurcation module 234 includes a lower support portion
236 having the two-lobed cross-section which is described in
co-pending U.S. patent application Ser. No. 08/538,706
(Attorney-Docket No. 16380-003800), previously incorporated herein
by reference. The relatively narrow mid-section 238 allows axial
bending of the assembled prosthesis through the aneurysm to adapt
to physiological movement.
[0104] Referring finally to FIG. 19, a short trunk branching
prosthesis includes a lumen separation portion 242 which is
adjacent to a trunk sealing cuff 246, here shown as a single
independent ring frame which is crown stitched to the liner.
Advantageously, the branch portions 248 will tend to have good
axial flexibility due to their significantly smaller diameter than
the trunk. Hence, the branch portions may be supported by
independently ring-frames.
[0105] Although the exemplary embodiments have been described in
some detail, by way of illustration and example, the scope of the
present invention is limited solely by the appended claims.
* * * * *