U.S. patent application number 10/616274 was filed with the patent office on 2004-06-03 for bifurcated endoluminal prosthesis.
Invention is credited to Cragg, Andrew H., Dake, Michael D., Goicoechea, George, Hudson, John, Mialhe, Claude.
Application Number | 20040106979 10/616274 |
Document ID | / |
Family ID | 56289802 |
Filed Date | 2004-06-03 |
United States Patent
Application |
20040106979 |
Kind Code |
A1 |
Goicoechea, George ; et
al. |
June 3, 2004 |
Bifurcated endoluminal prosthesis
Abstract
An introducer for delivering into the vasculature a straight or
bifurcated stent or prosthesis; a method for delivering into the
vasculature a straight or bifurcated stent or prosthesis; a method
of treating and angeological disease using a bifurcated stent; an
endoluminal stent having perpendicular hoop members, each hoop
member formed of wire in a sinuous configuration, at least some of
juxtaposed apices in neighboring hoops being secured to one
another, such stents also forming axially aligned segments in
straight stents, and segments of bifurcated stents in particular
embodiments. Certain embodiments of such stents also include barbs,
fabric covering and radiopaque markers.
Inventors: |
Goicoechea, George;
(Freeport, BS) ; Mialhe, Claude; (Draguignan,
FR) ; Hudson, John; (Glenfield, GB) ; Cragg,
Andrew H.; (Edina, MN) ; Dake, Michael D.;
(Stanford, CA) |
Correspondence
Address: |
RATNERPRESTIA
P O BOX 980
VALLEY FORGE
PA
19482-0980
US
|
Family ID: |
56289802 |
Appl. No.: |
10/616274 |
Filed: |
July 9, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10616274 |
Jul 9, 2003 |
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08463987 |
Jun 5, 1995 |
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08463987 |
Jun 5, 1995 |
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08317763 |
Oct 4, 1994 |
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5609627 |
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08317763 |
Oct 4, 1994 |
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08312881 |
Sep 27, 1994 |
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10616274 |
Jul 9, 2003 |
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08312881 |
Sep 27, 1994 |
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Current U.S.
Class: |
623/1.13 ;
623/1.35 |
Current CPC
Class: |
A61F 2/07 20130101; A61F
2002/065 20130101; A61F 2/852 20130101; A61F 2/90 20130101; A61F
2210/0019 20130101; A61F 2220/0016 20130101; A61F 2250/0098
20130101; Y10T 29/49826 20150115; A61F 2002/8486 20130101; A61M
25/0662 20130101; A61F 2/954 20130101; A61F 2220/0033 20130101;
A61F 2230/0067 20130101; A61F 2/82 20130101; A61F 2220/0008
20130101; A61F 2002/828 20130101; A61F 2220/0066 20130101; A61F
2/958 20130101; A61F 2240/001 20130101; Y10S 623/903 20130101; A61F
2002/061 20130101; A61F 2220/0075 20130101; A61F 2002/075
20130101 |
Class at
Publication: |
623/001.13 ;
623/001.35 |
International
Class: |
A61F 002/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 9, 1994 |
EP |
EP94400284.9 |
Jun 10, 1994 |
EP |
EP94401306.9 |
Claims
What is claimed:
1. An introducer for delivering, into the vasculature at an
angeological bifurcation where a blood vessel branches into two
branched vessels, a bifurcated endoluminal stent or prosthesis
having a proximal portion adapted to be disposed in said blood
vessel and a distal portion adapted to be disposed at least
partially in one of said two branched vessels, said introducer
comprising: (a) a tubular outer sheath; (b) a proximal portion
pusher disposed at least partially within said outer sheath; and
(c) a distal portion pusher disposed at least partially within said
proximal portion pusher.
2. An introducer for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 1 further comprising a balloon
catheter, having a balloon attached thereto, disposed at least
partially within said distal portion pusher.
3. An introducer for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 2 further comprising a hemostasis
valve attached to the distal end of said distal portion pusher.
4. An introducer for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 2 further comprising wings on said
outer sheath and said proximal portion pusher.
5. An introducer for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 2, wherein said balloon catheter has
an injection orifice and an injection conduit therein.
6. An introducer for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 2, wherein said balloon catheter has
an inflation orifice and an inflation conduit therein.
7. An introducer for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 2, wherein said balloon catheter has
a proximal end with a nose cone attached thereto.
8. An introducer for delivering into the vasculature at an
angeological bifurcation where a blood vessel branches into two
branched vessels, an endoluminal prosthesis having a proximal stent
portion and a distal stent portion, said introducer comprising: (a)
a tubular outer sheath; (b) a proximal portion pusher disposed at
least partially within said outer sheath and having a proximal end
adapted to contact said proximal stent portion; (c) a distal
portion pusher disposed at least partially within said proximal
portion pusher and having a proximal end adapted to contact said
distal stent portion; and (d) a balloon catheter, having a balloon
attached thereto, disposed at least partially within said distal
portion pusher.
9. An introducer for delivering an endoluminal stent into the
vasculature at an angeological bifurcation where a blood vessel
branches into two branched vessels, said introducer comprising: (a)
a tubular outer sheath; (b) a proximal portion pusher disposed at
least partially within said outer sheath and having a proximal end
adapted to contact a distal end of said stent; and (c) a distal
portion pusher disposed at least partially within said proximal
portion pusher and secured to said proximal portion pusher such
that proximal ends of said distal portion pusher and said proximal
portion pusher are flush with one another.
10. A method for delivering a bifurcated endoluminal stent or
prosthesis having a proximal portion and a first distal portion
into the vasculature at an angeological bifurcation where a blood
vessel branches into a first branched vessel and a second branched
vessel, said method comprising the steps of: (a) inserting a first
introducer containing said stent or prosthesis into the vasculature
to a predetermined delivery location, said first introducer
comprising an outer sheath, a proximal portion pusher, and a distal
portion pusher; (b) withdrawing said outer sheath of said first
introducer while maintaining said proximal portion pusher in a
fixed position until said proximal portion of said stent or
prosthesis is deployed from said first introducer into said blood
vessel; (c) withdrawing said outer sheath and said proximal portion
pusher while maintaining said distal portion pusher in a fixed
position until said first distal portion of said stent or
prosthesis is deployed from said first introducer at least
partially into said first branched vessel; and (d) withdrawing said
first introducer from the vasculature.
11. A method for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 10 further comprising the steps of:
(a) inserting into the vasculature a second introducer containing a
second distal portion of said stent or prosthesis and comprising an
outer sheath and a pusher; (b) withdrawing said outer sheath of
said second introducer while maintaining said pusher of said second
introducer in a fixed position until said second distal portion of
said stent or prosthesis is deployed from said second introducer
such that a proximal end of said second distal portion securely
connects to said proximal portion of said stent or prosthesis, and
such that a distal end of said second distal portion extends at
least partially into said second branched vessel; and (c)
withdrawing said second introducer from the vasculature.
12. A method for delivering a bifurcated endoluminal stent or
prosthesis as claimed in claim 10 wherein said first introducer
further comprises a balloon catheter having a balloon attached
thereto and said method further comprises the step of inflating
said balloon to at least partially block blood flow in said blood
vessel after inserting said first introducer into the
vasculature.
13. A method for delivering, into the vasculature at an
angeological bifurcation where a blood vessel branches into two
branched vessels, an endoluminal prosthesis having a proximal stent
portion, and a distal stent portion, said method comprising the
steps of: (a) inserting an introducer containing said prosthesis
into the vasculature to a predetermined delivery location, said
introducer comprising an outer sheath, a proximal stent portion
pusher, a distal stent portion pusher, and a balloon catheter
having a balloon attached thereto; (b) inflating said balloon to at
least partially block blood flow in said blood vessel; (c)
withdrawing said outer sheath of said introducer while maintaining
said proximal stent portion pusher in a fixed position until said
proximal stent portion of said prosthesis is deployed from said
introducer into said blood vessel; (d) withdrawing said outer
sheath and said proximal stent portion pusher while maintaining
said distal stent portion pusher in a fixed position until said
distal stent portion of said prosthesis is deployed from said
introducer into said blood vessel; and (e) withdrawing said
introducer from the vasculature.
14. A method of treating an angeological disease at a bifurcation
site where a blood vessel branches into a first branched vessel and
a second branched vessel comprising the steps of: (a) disposing in
said blood vessel a proximal portion of an endoluminal stent; (b)
directing blood flow from said blood vessel into said first
branched vessel through a first distal portion of said endoluminal
stent, said first distal portion being connected to said proximal
portion and extending into said first branched vessel; and (c)
directing blood flow from said blood vessel into said second
branched vessel through a second distal portion of said endoluminal
stent, said second distal portion being connected to said proximal
portion and extending into said second branched vessel.
15. A method of treating an angeological disease at a bifurcation
site where a blood vessel branches into a first branched vessel and
a second branched vessel as claimed in claim 14 wherein said
disease is stenosis.
16. A method of treating an angeological disease at a bifurcation
site where a blood vessel branches into a first branched vessel and
a second branched vessel as claimed in claim 14 that further
comprises covering any of said proximal portion, said first distal
portion, and said second distal portion with fabric.
17. A method of treating an angeological disease at a bifurcation
site where a blood vessel branches into a first branched vessel and
a second branched vessel as claimed in claim 16 wherein said
disease is an aneurysm.
18. A method of treating an angeological disease at a bifurcation
site where a blood vessel branches into a first branched vessel and
a second branched vessel as claimed in claim 16 wherein said
disease is an occlusion.
19. An endoluminal stent comprising a plurality of hoops which are
axially displaced in a tubular configuration along a common axis,
each of said hoops (a) being formed by a substantially complete
turn of a sinuous wire having apices, and (b) having a
circumference that lies in a plane substantially perpendicular to
the longitudinal axis of said stent; wherein apices of adjacent
hoops are juxtaposed to one another, and at least two juxtaposed
apices are connected by a securing means.
20. A stent as recited in claim 19 in combination with one or more
additional stent segments.
21. A stent as recited in claim 20 wherein at least one of said
additional stent segments comprises a plurality of hoops which are
axially displaced in a tubular configuration along a common axis,
each of said hoops (a) being formed by a substantially complete
turn of a sinuous wire having apices, and (b) having a
circumference that lies in a plane substantially perpendicular to
the longitudinal axis of said stent; wherein apices of adjacent
hoops are juxtaposed to one another, and at least two juxtaposed
apices are connected by a securing means.
22. A stent as recited in claim 20 wherein said one or more
additional segments are axially aligned with one another.
23. A stent as recited in claim 20 wherein said one or more
additional segments are secured to one another by connecting means
connecting at least some of the apices of hoops at mating ends of
said stent and said additional segments.
24. A stent as recited in claim 20 wherein adjacent hoops are of
the same diameter.
25. A stent as recited in claim 20 wherein adjacent hoops are of a
different diameter.
26. A stent as recited in claim 22 wherein said axially aligned
segments are connected to one another by a tubular fabric
element.
27. A stent as recited in claim 20 wherein a first additional
segment is axially parallel to, but non-common co-axial with, said
stent.
28. A stent as recited in claim 27 further comprising a second
additional segment axially parallel to said stent, but non-co-axial
with either said stent or said first additional stent segment.
29. A stent as recited in claim 28 wherein at least one of said
additional stent segments is of frustoconical shape and is further
combined with an additional stent segment, one end of which
includes a mating frustoconical shape.
30. A stent as recited in claim 29, wherein said mating
frustoconical stent segments are adapted to be separately placed in
a bifurcated artery and then, by expansion of one of said
frustoconical stent segments, secured to one another
31. An endoluminal stent as claimed in claim 19 wherein said hoops
are formed of a single continuous wire.
32. An endoluminal stent as claimed in claim 19 wherein said
securing means is a suture.
33. An endoluminal stent as claimed in claim 32 wherein said suture
is a tied loop of thermoplastic material.
34. An endoluminal stent as claimed in claim 19 wherein said
securing means is a ring.
35. An endoluminal stent as claimed in claim 19 wherein said
securing means is a staple.
36. An endoluminal stent as claimed in claim 19 wherein said
securing means is wire twisted into loop.
37. An endoluminal stent as claimed in claim 36 wherein said wire
is nitinol.
38. An endoluminal stent as claimed in claim 19 wherein said
securing means is bead of thermoplastic material.
39. An endoluminal stent as claimed in claim 19 wherein the plane
of the circumference at each longitudinal end of the stent is
square to the longitudinal axis of the stent.
40. An endoluminal stent as claimed in claim 19 wherein said stent
is at least partially covered in fabric.
41. An endoluminal stent as claimed in claim 31 wherein said wire
is nitinol.
42. A method of making an endoluminal stent having a plurality of
hoops which are axially displaced in a tubular configuration, each
of said hoops being formed by a substantially complete turn of a
sinuous wire with apices and having a circumference that lies in a
plane substantially perpendicular to the longitudinal axis of the
stent, said method comprising the steps of: (a) winding a wire in a
zig-zag pattern around a mandrel having a plurality of upstanding
pins defining said zig-zag pattern to form a first hoop having
apices and a circumference that lies in a plane substantially
perpendicular to the longitudinal axis of said mandrel; (b)
longitudinally displacing said wire with respect to the axis of
said mandrel; (c) winding said wire in a zig-zag pattern around a
plurality of upstanding pins on said mandrel to form a second hoop,
adjacent said first hoop, having apices juxtaposed to the apices of
said first circumferential hoop and a circumference that lies in a
plane substantially perpendicular to the longitudinal axis of said
mandrel; (d) longitudinally displacing said wire with respect to
the axis of said mandrel; (e) repeating steps (a)-(d) to form
additional hoops until a predetermined number of hoops are formed;
(f) annealing said wire on said mandrel; (g) cooling said wire on
said mandrel; (h) removing said wire from said mandrel; and (i)
securing together at least two juxtaposed apices of adjacent
hoops.
43. An endoluminal stent comprising a radiopaque marker disposed on
at least one end of the stent.
44. An endoluminal stent as claimed in claim 43 wherein said
radiopaque marker comprises a radiopaque element attached to one
end of said stent.
45. An endoluminal stent as claimed in claim 44 wherein said
element is a platinum wire.
46. An endoluminal stent as claimed in claim 44 wherein said
element is a gold wire.
47. An endoluminal stent as claimed in claim 43 wherein said
radiopaque marker comprises a radiopaque tube disposed around a
part of said stent.
48. An endoluminal stent as claimed in claim 47 wherein said tube
is platinum.
49. An endoluminal stent as claimed in claim 47 wherein said tube
is gold.
50. A bifurcated stent for use in juxtaposition with an
angeological bifurcation comprising a proximal stent portion
adapted to be disposed within a blood vessel in juxtaposition with
a bifurcation, a first distal stent portion adapted to extend
across the bifurcation into one of the branched blood vessels, and
a second distal stent portion adapted to allow blood to flow from
the proximal portion into the other branched vessel and, at least
one barb extending radially outward from any of said proximal stent
portion, said first distal stent portion, and said second distal
stent portion.
51. Apparatus for delivering an endoluminal stent or prosthesis
into the vasculature comprising: (a) an introducer having a on a
distal end thereof; and (b) a cartridge having an inner tubular
member containing said stent or prosthesis in a compressed state,
an outer sheath, and a second portion of said lock fitting; wherein
said first portion of said lock fitting on said introducer mates
with said second portion of said lock fitting on said cartidge to
prevent relative movement of said introducer and said
cartridge.
52. Apparatus as claimed in claim 51 wherein said lock fitting is a
Luer lock.
53. Apparatus as claimed in claim 51 further comprising a
hemostasis valve on said introducer and a pusher adapted to push
said compressed stent or prosthesis through said cartridge, through
said introducer, and into the vasculature.
Description
[0001] This is a continuation-in-part application of the
application of common assignment herewith of inventors George
Goicoechea, Claude Mialhe, John Hudson and Andrew Cragg, entitled
BIFURCATED ENDOLUMINAL PROSTHESIS, filed on Sep. 27, 1994, for
which application a serial number had not yet been assigned as of
the date of filing this continuation-in-part application.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a bifurcated endoluminal
prosthesis for use in a bifurcated blood vessel such, for example,
as the infrarenal portion of a mammalian aortic artery where it
bifurcates to the common iliac arteries. The present invention also
embraces a stent connecting means for connecting a stent (e.g. a
stent which forms part of an endoluminal prosthesis) to another
stent, as well as apparatus and method for introducing prostheses
to the vasculature and methods of treating angeological
diseases.
[0003] A stent is used to provide a prosthetic intraluminal wall
e.g. in the case of a stenosis to provide an unobstructed conduit
for blood in the area of the stenosis. An endoluminal prosthesis
comprises a stent which carries a prosthetic graft layer of fabric
and is used e.g. to treat an aneurysm by removing the pressure on a
weakened part of an artery so as to reduce the risk of embolism, or
of the natural artery wall bursting. Typically, a stent or
endoluminal prosthesis is implanted in a blood vessel at the site
of a stenosis or aneurysm by so-called "minimally invasive
techniques" in which the stent is compressed radially inwards and
is delivered by a catheter to the site where it is required through
the patient's skin or by a "cut down" technique in which the blood
vessel concerned is exposed by minor surgical means. When the stent
is positioned at the correct location, the catheter is withdrawn
and the stent is caused or allowed to re-expand to a predetermined
diameter in the vessel.
[0004] U.S. Pat. No. 4,886,062 discloses a vascular stent which
comprises a length of sinuous or "zig-zag" wire formed into a
helix; the helix defines a generally cylindrical wall which, in
use, constitutes a prosthetic intraluminal wall. The sinuous
configuration of the wire permits radial expansion and compression
of the stent; U.S. Pat. No. 4,886,062 discloses that the stent can
be delivered percutaneously and expanded in situ using a balloon
catheter.
[0005] U.S. Pat. No. 4,733,665 discloses an expandable intraluminal
graft which is constituted by a tubular member formed from a
plurality of intersecting elongate members which permit radial
expansion and compression of the stent.
[0006] EP-A-0556850 discloses an intraluminal stent which is
constituted by a sinuous wire formed into a helix; juxtaposed
apices of the wire are secured to one another so that each hoop of
the helix is supported by its neighboring hoops to increase the
overall strength of the stent and to minimize the risk of plaque
herniation; in some embodiments the stent of EP-A-0556850 further
comprises a tubular graft member to form an endoluminal
prosthesis.
[0007] The prior art stents and prostheses mentioned above are
generally satisfactory for the treatment of aneurysms, stenoses and
other angeological diseases at sites in continuous unbifurcated
portions of arteries or veins.
[0008] However, the prior art stents and prostheses are not wholly
satisfactory for use where the site of desired application of the
stent or prosthesis is juxtaposed or extends across a bifurcation
in an artery or vein such, for example, as the bifurcation in the
mammalian aortic artery into the common iliac arteries. For
example, in the case of an abdominal aortic aneurysm ("AAA") in the
infrarenal portion of the aorta which extends into one of the
common iliac arteries, the use of one of the prior art prosthesis
referred to above across the bifurcation into the one iliac artery
will result in obstruction of the proximal end of the other common
iliac artery; by-pass surgery is therefore required to connect the
one iliac artery in juxtaposition with the distal end of the
prosthesis to the other blocked iliac artery. It will be
appreciated by a person skilled in the art that it is desirable to
avoid surgery wherever possible; the requirement for by-pass
surgery associated with the use of the prior art prosthesis in
juxtaposition with a bifurcation in an artery therefore constitutes
a significant disadvantage.
SUMMARY OF THE INVENTION
[0009] Throughout this specification, the term "proximal" shall
mean "nearest to the heart," and the term "distal" shall mean
"furthest from the heart."
[0010] According to one aspect of the present invention there is
provided a stent connecting means for connecting two intraluminal
stents one to the other to define a continuous lumen through the
two stents, the stent connecting means including a first stent
including a male engaging portion which can be compressed radially
inwardly, and a second stent including a female cooperating
portion. The male engaging portion may be entered into the female
cooperating portion in a radially compressed state and thereafter
caused or allowed to expand in the female cooperating portion; the
arrangement being such that in service the interengagement of the
male engaging portion and the female cooperating portion serves to
resist longitudinal separation of the two stents one from the
other.
[0011] Typically, the first stent may include a proximal male
engaging portion; the second stent may include a distal female
cooperation portion. The male engaging portion may be flared
radially outwardly towards its extremity, and the female
cooperating portion may be tapered radially inwardly towards its
extremity. In some embodiments, the male engaging portion may
comprise a frustoconical wall which flares outwardly towards its
longitudinal extremity; the female engaging portion may comprise a
frustoconical wall which tapers radially inwardly towards its
longitudinal extremity.
[0012] Alternatively, said male engaging and female cooperating
portions may be substantially untapered; they may be substantially
cylindrical.
[0013] The male engaging portion of the first stent may be
resiliently compressible in a radially inwards direction such that
in the radially compressed state it is capable of self-reexpansion
to engage in the female cooperating portion. Typically, each of
said first and second stents may be resiliently compressible.
[0014] In use therefore the second stent may be delivered in a
radially compressed state by using a catheter; when the second
stent is located at the site of use, the catheter may be withdrawn
thereby allowing the second stent to re-expand to engage the
endoluminal surface of the blood vessel.
[0015] The first stent may then be delivered percutaneously or by a
"cut down" technique to a site distal of the second stent such that
the male engaging portion of the first stent in the radially
compressed state is entered into the expanded female cooperating
portion of the second stent; the catheter may then be withdrawn
allowing the first stent to re-expand such that the male engaging
portion engages in the female cooperating portion of the second
stent.
[0016] In some embodiments of the present invention the second
stent may have two transversely spaced distal female cooperating
portions; the second stent may therefore constitute a bifurcated
stent for use in juxtaposition with a bifurcation in a blood
vessel.
[0017] Each of the two transversely spaced distal female
cooperating portions may be adapted for connection to a first male
stent which, in use, extends across the bifurcation into a
respective one of the branched blood vessels.
[0018] In a particular aspect of the present invention there is
provided a bifurcated intraluminal stent for use in juxtaposition
with an angeological bifurcation; the bifurcated intraluminal stent
comprising a proximal portion adapted to be positioned in service
in a blood vessel in juxtaposition with a bifurcation, a first
distal stent portion adapted to extend across the bifurcation into
one of the branched blood vessels and a second distal stent portion
adapted to allow blood to flow from the proximal portion into the
other branched vessel. The first distal stent portion may be formed
integrally with the proximal portion.
[0019] In some embodiments the second distal stent portion may
comprise a female cooperating portion which is adapted to engage a
male engaging portion of a another stent adapted to extend in the
other branched blood vessel such that, in use, the bifurcated stent
can be connected in situ to the other stent. The bifurcated
intraluminal stent may therefore constitute a second stent in
accordance with the present invention comprising a distal female
cooperating portion disposed intermediate the proximal and distal
extremities of the stent; the other stent may constitute a first
stent in accordance with the present invention.
[0020] Typically, the proximal end of said second stent may be
flared radially outwardly towards its extremity to engage the
endoluminal surface of the artery thereby to resist longitudinal
movement of the second stent in service.
[0021] Each of the first and second stents may comprise a sinuous
wire formed into a tubular configuration. The sinuous and tubular
configurations may be imparted to the wire by winding it on a
mandrel. Typically, each stent may be made from a shape memory
nitinol (nickel-titanium) wire which may be wound on to the mandrel
to form the stent in a tubular configuration of slightly greater
diameter than the diameter of the blood vessel in which the stent
is intended to be used. The stent may be annealed at an elevated
temperature and then allowed to cool in air so that the nitinol
wire "remembers" the configuration in which it was wound on the
mandrel.
[0022] Said nitinol wire may be type "M" nitinol wire which is
martensitic at temperatures below about 13.degree. C. and is
austenitic at temperatures above about 25.degree. C.; it will be
appreciated therefore that the type "M" wire will be austenitic at
body temperature of 37.degree. C. Typically, the annealing may be
conducted at about 500.degree. C. or more for at least about 60
minutes; after cooling the wire may be immersed in cold water to
facilitate removal of the wire from the mandrel with the wire in
its maleable martensitic form. Typically, the cold water may have
temperature of less than about 10.degree. C.; the wire may be
immersed for about 5 minutes or more. An advantage of using nitinol
wire to form the stent in accordance with the present invention is
that the nitinol wire is "super elastic" in its austenitic state;
the radial outward force exerted by the stent on the wall of the
blood vessel in use is therefore substantially constant
irrespective of the diameter of the vessel and the expanded
stent.
[0023] In some embodiments the wire may have a helical
configuration as disclosed in EP-A-0556850. Alternatively, the wire
may be of an entirely novel configuration, namely one in which the
wire forms a plurality of hoops such that the plane of the
circumference of each hoop is substantially perpendicular to the
longitudinal axis of the stent. Each hoop may comprise a
substantially complete turn of the wire having a sinuous
configuration; optionally, as each hoop is completed, the point of
winding the wire may be displaced longitudinally with respect to
the winding axis to form the next hoop. When the next hoop is
complete, the point of winding is moved further longitudinally with
respect to the winding axis to the form the next succeeding hoop
and so on.
[0024] It will appreciated that an advantage of this novel
arrangement is that the planes of the hoops are not skewed with
respect to the longitudinal axis of the stent; the longitudinal
ends of the stent are "square" to said longitudinal axis, so that
when the stent is caused or allowed to expand in situ there is
substantially no twisting of the stent as it shortens in length. It
will be appreciated that this represents a significant advantage,
as in areas of stenosis or aneurysm it is desirable to minimize the
movement of the stent within the blood vessel so as to reduce the
potential trauma to the patient. A stent of this configuration may
be used, apart from the bifurcated embodiment otherwise taught
herein, in any application which in stents generally have heretofor
been used.
[0025] Typically, the stents of this invention whether of the
helical or perpendicular variety, also comprise a securing means
for securing an apex of the sinuous wire in one hoop to a
juxtaposed apex of a neighboring hoop so that each hoop is
supported by its neighbors. The securing means may comprise a loop
element of a suture material, for example, to tie the juxtaposed
apices together; the loop element may also comprise a loop formed
of a thermoplastics material such, for example, as polypropylene.
Alternatively, the securing means may be a bead formed of a
thermoplastic material around juxtaposed apices. Also
alternatively, the securing means may be a loop, ring, or staple
formed of wire such as nitinol.
[0026] The male engaging portion and female cooperating portion, of
the first and second interengaging stents of this invention, may be
formed separately from the remainder of the respective non-engaging
portions of these stents and then the engaging and non-engaging
portions secured to one another by securing means.
[0027] In one embodiment of the present invention, the proximal and
distal stent portions of the bifurcated stent in accordance with
the present invention may be formed separately; the distal end of
the proximal stent portion may be secured to the wider proximal end
of a first intermediate frustoconical stent portion; the narrower
distal end of the first intermediate frustoconical stent portion
may be secured to the proximal end of the distal stent portion. The
female cooperating portion of the bifurcated stent may be
constituted by a second frustoconical stent portion which is
secured to the distal end of the proximal stent portion in
juxtaposition with the first frustoconical portion.
[0028] Alternatively the first and second frustoconical portions
may be omitted; the proximal and distal stent portions may be
secured directly one to the other.
[0029] The female cooperating portion may be constituted by a
generally cylindrical stent portion secured to said proximal stent
portion in transversely spaced relation to the distal portion.
[0030] Each of the first and second stents of the bifurcated form
of the present invention may carry a tubular graft layer formed
from a biocompatible fabric in juxtaposition with the stent; the
combined stent and graft layer constituting an endoluminal
prosthesis. Typically the graft layer may be disposed externally of
the stent; it will be appreciated however that in some embodiments
the graft layer may be disposed internally of the stent. In some
embodiments the graft layer may be secured to the stent by loop
elements such, for example, as loops of polypropylene. The
biocompatible fabric may be a polyester fabric or a
polytetrafluoroethylene fabric; typically said fabric may be woven
or a warp knitted polyester fabric. In some embodiments the woven
or a warp knitted fabric may be formed in a seam-free bifurcated
configuration as a sleeve for a bifurcated stent.
[0031] In some embodiments the male engaging portion of the first
stent and the female cooperating portion of the second stent may be
left uncovered. Alternatively, the fabric graft layer may extend to
the proximal extremity on the external surface of the male engaging
portion, and may be folded over the distal extremity of the female
engaging portion to form an inner sleeve; in use the external
fabric of the male engaging portion may butt against the folded
over portion of the fabric internally of the female cooperating
portion to form a substantially blood tight seal.
[0032] The present invention in one aspect therefore includes a
bifurcated endoluminal prosthesis comprising a bifurcated stent in
accordance with the invention and a tubular graft layer.
[0033] The first stent having the male engaging portion may also
have a tubular graft layer. If required the first prosthesis may be
introduced in a radially compressed state such that the male
engaging portion of the first prosthesis is engaged in the
intermediate female cooperating portion of the bifurcated
prosthesis; the first prosthesis is then caused to be allowed to
re-expand in situ such that the male engaging portion engages in
the female cooperating portion to resist longitudinal separation of
the two prosthesis in service.
[0034] The bifurcated prosthesis may be adapted for use in the
infrarenal portion of a mammalian aorta in juxtaposition with the
bifurcation of the common iliac arteries for the treatment of
abdominal aortic aneurysms. In use the bifurcated endoluminal
prosthesis may be introduced into the infrarenal portion of the
aorta using a catheter such that the first distal stent portion
extends into one of the branched iliac arteries; the catheter may
then be withdrawn allowing the prosthesis to re-expand in situ.
[0035] It will be appreciated by a person skilled in the art that
the prostheses may be introduced to the site of use percutaneously
or by "cut down" techniques.
[0036] Any of the stents according to this invention may be
provided on its external surface with circumferentially spaced wire
barbs or hooks adapted to engage in the endoluminal surface of the
host artery to resist longitudinal movement or slippage of the
stent in use. Typically the barbs or hooks may be disposed on part
of the stent which is provided with a fabric graft layer such that
in use the points of the artery which are engaged by the barbs or
hooks are covered by the fabric graft. It will be appreciated by a
person skilled in the art that the trauma to the artery wall caused
by the hooks or barbs may cause emboli; the provision of the fabric
graft over the barbs or hooks in use will therefore help to prevent
the introduction of such emboli into the blood stream.
[0037] The male engaging portion for the first stent may be
provided with circumferentially spaced hooks or barbs on its
external surface to engage the internal surface of said female
cooperating means, thereby to reinforce the connecting means
against longitudinal separation of the stents one from the other in
the service.
[0038] The present invention therefore provides a connecting means
for connecting two stents longitudinally one to the other. It will
be appreciated that this represents a significant step forward in
the art as it allows the provision of a bifurcated endoluminal
prosthesis for use in juxtaposition e.g. with arterial bifurcations
without requiring by pass surgery to connect one of the branched
arteries to the other branched artery.
[0039] In particular, the invention provides a bifurcated
endoluminal prosthesis which can be positioned in an artery in
juxtaposition with a bifurcation to extend into one of the branched
arteries; the bifurcated prosthesis can be connected to another
prosthesis which extends into the other branched artery. The
prosthesis can be delivered percutaneously or by "cut down" methods
and connected together in situ thereby to provide effective
treatment of an angeological disease such, for example, as an
aneurysm or a stenosis which extends across a bifurcation in a
blood vessel without the need for by-pass surgery.
[0040] In another aspect, this invention provides an introducer for
delivering, into the vasculature at an angeological bifurcation
where a blood vessel branches into two branched vessels, a
bifurcated endoluminal stent or prosthesis having a proximal
portion adapted to be disposed in the blood vessel and a distal
portion adapted to be disposed at least partially in one of the two
branched vessels. The introducer comprises a tubular outer sheath,
a proximal portion pusher disposed at least partially within the
outer sheath, and a distal portion pusher disposed at least
partially within the proximal portion pusher.
[0041] The present invention further provides an introducer for
delivering into the vasculature at an angeological bifurcation
where a blood vessel branches into two branched vessels, an
endoluminal prosthesis having a proximal stent portion and a distal
stent portion. The introducer comprises a tubular outer sheath, a
proximal portion pusher disposed at least partially within the
outer sheath and having a proximal end adapted to contact the
proximal stent portion, a distal portion pusher disposed at least
partially within the proximal portion pusher and having a proximal
end adapted to contact the distal stent portion; and a balloon
catheter, having a balloon attached thereto, disposed at least
partially within the distal portion pusher.
[0042] This invention in another aspect provides a method for
delivering a bifurcated endoluminal stent or prosthesis having a
proximal portion and a first distal portion into the vasculature at
an angeological bifurcation where a blood vessel branches into a
first branched vessel and a second branched vessel. The method
comprises inserting a first introducer containing the stent or
prosthesis into the vasculature to a predetermined delivery
location, the first introducer comprising an outer sheath, a
proximal portion pusher, and a distal portion pusher; withdrawing
the outer sheath of the first introducer while maintaining the
proximal portion pusher in a fixed position until the proximal
portion of the stent or prosthesis is deployed from the first
introducer into the blood vessel; withdrawing the outer sheath and
the proximal portion pusher while maintaining the distal portion
pusher in a fixed position until the first distal portion of the
stent or prosthesis is deployed from the first introducer at least
partially into the first branched vessel; and withdrawing the first
introducer from the vasculature.
[0043] This invention further provides a method for delivering,
into the vasculature at an angeological bifurcation where a blood
vessel branches into two branched vessels, an endoluminal
prosthesis having a proximal stent portion, and a distal stent
portion. The method comprises the steps of inserting an introducer
containing the prosthesis into the vasculature to a predetermined
delivery location, the introducer comprising an outer sheath, a
proximal stent portion pusher, a distal stent portion pusher, and a
balloon catheter having a balloon attached thereto; inflating the
balloon to at least partially block blood flow in the blood vessel;
withdrawing the outer sheath of the introducer while maintaining
the proximal stent portion pusher in a fixed position until the
proximal stent portion of the prosthesis is deployed from the
introducer into the blood vessel; withdrawing the outer sheath and
the proximal stent portion pusher while maintaining the distal
stent portion pusher in a fixed position until the distal stent
portion of the prosthesis is deployed from the introducer into the
blood vessel; and withdrawing the introducer from the
vasculature.
[0044] In general, this invention provides a method of treating an
angeological disease at a bifurcation site where a blood vessel
branches into a first branched vessel and a second branched vessel
comprising the steps of disposing in the blood vessel a proximal
portion of an endoluminal stent; directing blood flow from the
blood vessel into the first branched vessel through a first distal
portion of the endoluminal stent, the first distal portion being
connected to the proximal portion and extending into the first
branched vessel; and directing blood flow from the blood vessel
into the second branched vessel through a second distal portion of
the endoluminal stent, the second distal portion being connected to
the proximal portion and extending into the second branched vessel.
This method may be applied to aneurysms, occlusions, or
stenosis.
[0045] Following is a description by way of example only and with
reference to the accompanying drawings of the present invention,
including novel stent constructions and methods of manufacture and
use thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] The aspects, features and advantages of the present
invention will be more readily understood from the following
detailed description when read in conjunction with the accompanying
drawings, in which:
[0047] FIG. 1a is a front view of a bifurcated intraluminal stent
in accordance with the present invention constituting part of an
endoluminal prosthesis.
[0048] FIG. 1b is a front view of another stent which is adapted to
be connected to the bifurcated stent of FIG. 1a.
[0049] FIG. 2(a) is a side view of part of the bifurcated stent of
FIG. 1a opened up to show its construction.
[0050] FIG. 2(b) is a side view of an exemplary mandrel used to
form the part of the bifurcated stent shown in FIG. 2(a).
[0051] FIG. 3 is a side view of another part of the bifurcated
stent of FIG. 1a opened up to show its construction.
[0052] FIG. 4(a) is a side view of yet another part of the
bifurcated stent of FIG. 1a opened up to show its construction.
[0053] FIGS. 4(b)-4(f) are partial exploded views of the exemplary
stent of FIG. 4(a) illustrating alternative means for securing
juxtaposed apices according to the present invention.
[0054] FIG. 5 is a schematic perspective view of a bifurcated
endoluminal prosthesis in accordance with the present
invention.
[0055] FIG. 6 is a schematic view of another bifurcated endoluminal
prosthesis in accordance with the present invention.
[0056] FIG. 7 is a schematic view of yet another bifurcated
endoluminal prosthesis in accordance with the present
invention.
[0057] FIG. 8(a) is a cross-sectional view of an exemplary
assembled introducer according to the present invention.
[0058] FIGS. 8(b)-8(e) are side views of the component parts of the
introducer of FIG. 8(a).
[0059] FIG. 8(f) is a partial cross-sectional view of the
introducer of FIG. 8(a).
[0060] FIG. 8(g) is a cross-sectional view of part of the
introducer of FIG. 8(f) taken along the line A-A.
[0061] FIG. 9 is a side cross-sectional view of a portion an
alternative embodiment of an introducer according to the present
invention.
[0062] FIGS. 10(a) and 10(b) are side views of other alternative
embodiments of an introducer according to the present
invention.
[0063] FIGS. 11 through 20 are sequential cross-sectional views of
the bifurcation of the abdominal aortic artery during introduction
of an exemplary prosthesis according to the present invention.
[0064] FIGS. 21(a)-21(c) are cross-sectional views of alternative
insertion apparatus according to the present invention.
[0065] FIGS. 22 and 23 are side views of alternative stents
according to the present invention.
[0066] FIGS. 24(a), 24(b), 25, 26 and 27 are sequential
cross-sectional views of the bifurcation of the abdominal aortic
artery during introduction of an exemplary prosthesis according to
the present invention.
[0067] FIGS. 28 and 29 are cross-sectional side views of
alternative delivery apparatus according to the present
invention.
[0068] FIGS. 30-34 are sequential cross-sectional views of the
bifurcation of the abdominal aortic artery during introduction of
an exemplary prosthesis according to the present invention.
DETAILED DESCRIPTION
[0069] The present invention includes apparatus and method for
treating angeological diseases in any bifurcated blood vessel. One
example of such a bifurcated blood vessel is the infrarenal portion
of a mammalian aortic artery where it bifurcates to the common
iliac arteries. Examples of diseases that can be treated using the
apparatus and method of the present invention include aneurysm,
stenosis, and occlusion.
[0070] A bifurcated stent in accordance with the present invention
which is indicated at 10 in FIG. 1a comprises a wire skeleton which
is constructed in four separate parts, namely a proximal part 12, a
first frustoconical part 14, a first distal part 16 and a second
frustoconical part 18. Said bifurcated stent 10 carries a fabric
graft layer (FIGS. 5, 6, and 7) for use as an endoluminal
prosthesis e.g. in the infrarenal portion of a mammalian aorta in
juxtaposition with the bifurcation of the common iliac arteries. It
will be appreciated, however, that bifurcated stents (with or
without fabric graft layers) for use in different parts of the
angeological system and for different mammals can be constructed in
accordance with the invention by varying the dimensions of the
stent accordingly.
[0071] Each of the four parts of the bifurcated stent 10 is made in
substantially the same way by winding a shape memory nitinol wire,
typically nitinol type M wire, onto a mandrel 46.
[0072] The construction of the exemplary proximal part 12 of the
bifurcated stent 10 is shown in FIGS. 2(a) and 2(b); nitinol wire
type M wire typically having a diameter of 0.46 mm (0.018") is
wound around mandrel 46 to form a plurality of hoops 20. The
winding surface of mandrel 46 is provided with a plurality of
upstanding pins 47 disposed in a zig-zag pattern for each of the
hoops 20 so that in each hoop 20 the nitinol wire follows a sinuous
path to define a plurality of circumferentially spaced apices 22.
Each hoop 20 is wound onto mandrel 46 such that the plane of the
circumference of each hoop 20 is substantially perpendicular to the
longitudinal axis of the mandrel.
[0073] When one hoop 20 e.g. the hoop indicated at 20a has been
formed, the point of winding of the nitinol wire is displaced
longitudinally with respect to the axis of mandrel 46 to form the
next successive hoop 20b. The stent shown in FIG. 2(a) is the stent
formed on mandrel 46 shown in FIG. 2(b) after cutting the stent
longitudinally and rotating it 45 degrees to show the construction
of the stent.
[0074] The proximal part of the exemplary bifurcated stent of FIG.
1a is formed on the mandrel with a diameter of about 24 mm and a
length in the longitudinal direction of about 55 mm. From FIGS.
1(a), 2(a), and 2(b) it will be noted that the proximal part 12 is
constituted by three hoops 20 of unit width at the proximal end 24
of the proximal part 12, two intermediate hoops 25 of twice unit
width and, at its distal end 26, by a single hoop 20 of unit width.
In the illustrated embodiment, intermediate hoops 25 have a
plurality of offsets 25a. Offsets 25a are formed when the wire is
passed around pins 47 on mandrel 46. Offsets 25a add stability to
the stent. When the nitinol wire has been wound onto mandrel 46,
the nitinol wire is annealed at an elevated temperature and then
allowed to cool.
[0075] In this embodiment of the invention the wire is annealed at
a temperature of about 500.degree. C. for 60 minutes and is then
allowed to cool in air. The purpose of the annealing is so that the
nitinol wire in its austenitic form "remembers" its configuration
as wound on mandrel 46; it will be appreciated therefore that other
temperatures and durations for the annealing are included within
the present invention provided the nitinol wire "remembers" its
wound configuration.
[0076] After annealing and cooling, the wire is immersed in cold
water at less than 10.degree. C. for about 5 minutes; the wire is
then removed from the mandrel, and juxtaposed apices 22 of
neighboring hoops 20 are secured together by securing means 99 (see
FIG. 4(a)), which are, in this example, 0.003" polypropylene
filaments. Each apex 22 of each hoop 20 which has a juxtaposed apex
of a neighboring hoop 20 is tied to the juxtaposed apex 22. It will
be appreciated, however, that in other embodiments of the invention
only some of the juxtaposed apices 22 may be secured in this
way.
[0077] In addition to polypropylene filaments, the securing means
may comprise a loop element 99a of a suture material, for example,
to tie the juxtaposed apices together, as shown in FIG. 4(b). The
securing means may also comprise bead 99b formed of a thermoplastic
material around juxtaposed apices, as shown in FIG. 4(c). Also
alternatively, the securing means may be a loop 99c, ring 99d, or
staple 99e formed of wire such as nitinol, as shown in FIGS. 4(d),
4(e), and 4(f) respectively.
[0078] The exemplary first and second frustoconical parts 14, 18 of
the skeleton shown in the figures are formed in substantially the
same way as the proximal part 12 by winding nitinol wire onto a
mandrel and then annealing the wire before removing it from the
mandrel. As shown in FIG. 3, the first and second frustoconical
parts 14, 18 are each constituted by three hoops 20 of unit width.
The mandrel is tapered such that the proximal end of each of the
exemplary frustoconical parts 14, 18 is formed with a diameter of
about 12 mm and the distal end 32 of each is formed with a diameter
of about 9 mm. The overall length of each of the exemplary
frustoconical parts 14, 18 is about 18 mm. The wire used for the
frustoconical parts 14, 18 is nitinol type M wire having a diameter
of 0.28 mm (0.011"). Juxtaposed apices 22 of each of the exemplary
frustoconical parts 14, 18 are tied together using 0.03"
polypropylene filaments as described above. The first and second
frustoconical parts 14, 18 are secured to the distal end 26 of the
proximal part 12 of the stent 10 in transversely spaced relation as
shown in FIG. 1a by securing the apices 22 of the hoop 20 forming
the wider proximal end 30 of each of the frustoconical parts 14, 18
to juxtaposed apices 22 of the hoop 20 on the distal end 26 of the
proximal part 12.
[0079] The exemplary first distal part 16 of the bifurcated stent
10 is formed by winding nitinol type M wire typically having a
diameter of 0.28 mm (0.011") onto a mandrel to form twelve
longitudinally spaced hoops 20 as shown in FIG. 4; the exemplary
first distal part has an overall length of about 66 mm and a
uniform diameter of about 9 mm. The proximal end 34 of the distal
part 16 is secured to the narrower distal end 32 of the first
frustoconical part 14 by tying each apex 22 on the proximal end 34
of the first distal part 16 to a juxtaposed apex on the distal end
32 of the first frustoconical part 14 using, in this embodiment,
0.003" polypropylene filaments.
[0080] The proximal part 12, the first and second frustoconical
parts 14, 18, and the first distal part 16 are each covered with a
tubular graft layer of a biocompatible woven fabric (FIGS. 5, 6,
and 7) such, for example, as a plain woven fabric made from 30 or
40 denier polyester. The tubular fabric layers may be attached to
the proximal and distal parts 12, 16 of the stent 10 by stitching
with, for example, 0.003" polypropylene filaments around the apices
22 of the underlying skeleton. The fabric covered stent constitutes
one form of an endoluminal prosthesis.
[0081] The proximal part 12 of the wire skeleton may be provided
with a plurality of circumferentially spaced hooks or barbs 43
which project through the tubular fabric layer to engage in the
endoluminal surface of a host artery in service.
[0082] The sinuous configuration of each turn 20 of the wire
skeleton of the stent 10 allows the prosthesis to be compressed
resiliently radially inwards so that it can be received in a
catheter e.g. a 16 or 18 French catheter for percutaneous or cut
down delivery, e.g. to an intraluminal site in the infrarenal
section of the aortic artery. Larger diameter catheters up to,
e.g., 20 French, may be used to deliver the prosthesis using "cut
down" procedures.
[0083] An x-ray opaque marker may be attached to one or more ends
of a stent so that the delivery of the stent can be monitored using
x-rays. As shown in FIG. 4(a), such a radiopaque marker may
typically comprise a gold or platinum wire 17 crimped onto an end
of stent 16. Alternatively, the radiopaque marker may be a tube 17a
disposed around a length of wire on the stent, also as shown in
FIG. 4(a). Typically, in the bifurcated stent the marker is secured
to the stent in line with the distal stent portion so that the
distal stent portion can be aligned with and inserted into one of
the branched arteries in situ.
[0084] The bifurcated endoprosthesis is positioned in the
infrarenal section of the aortic artery in juxtaposition with the
bifurcation of the common iliac arteries such that the first distal
part 16 of the prosthesis extends into one of the common iliac
arteries. The catheter is then withdrawn allowing the stent 10 to
re-expand towards its configuration as wound on the mandrel in
which it was annealed until the stent engages the endoluminal
surface of the host artery. The barbs or hooks engage the
endoluminal surface of the host artery to resist longitudinal
displacement or slipping of the prosthesis in use.
[0085] It will be appreciated that when the bifurcated prosthesis
is positioned and re-expanded in the fitted position, blood can
flow from the aortic artery into the proximal part 12 of the
prosthesis from where it can flow into the one common iliac artery
through the frustoconical part 14 and the first distal part 16 and
also into the other common iliac artery through the second
frustoconical part 18.
[0086] In cases where it is required to implant a prosthesis in the
other common iliac artery a second prosthesis comprising a second
stent 40 as shown in FIG. 1b can be used. The second stent 40
includes a wire skeleton comprising a proximal frustoconical part
42 and a distal part 44. The distal part 44 of the second stent 40
also may be covered with a tubular graft layer of a biocompatible
fabric such, for example, as polyester or polytetrafluoroethylene
fabric (FIGS. 5, 6, and 7).
[0087] The frustoconical proximal part 42 is constructed in the
same way as the frustoconical parts 14, 18 of the bifurcated stent
10; the distal part 44 is constructed in the same way as the distal
part 16 of the bifurcated stent 10. The distal end of the
frustoconical proximal part 42 is secured to the proximal end of
the distal part 44 by securing juxtaposed apices using
polypropylene filaments as described above.
[0088] In use, the second prosthesis is compressed radially inwards
and is received in a catheter for percutaneous or "cut down"
delivery to the other common iliac artery. The frustoconical
proximal part 42 is guided, in the radially compressed state, into
the second frustoconical part 18 of the bifurcated stent 10. The
catheter is then withdrawn allowing the second stent 40 to
re-expand towards its remembered configuration, until the distal
part 14 engages the endoluminal surface of the other common iliac
artery, and the outer surface of the frustoconical proximal part 42
engages the interior surface of the second frustoconical part 18 of
the bifurcated stent 10.
[0089] As with other stents described herein, the frustoconical
proximal part 42 may be formed with circumferentially spaced barbs
or hooks 43, as shown in FIG. 1b, which engage in the wire skeleton
of the second frustoconical part 18 of the bifurcated stent 10.
When barbs 43 are on proximal portion 12, they engage the inner
wall of the artery.
[0090] The tapered configurations of the second frustoconical part
18 of the bifurcated stent 10 and of the proximal frustoconical
part 42 of the second stent 40 are such that in the fitted position
as described, the prosthesis are locked together to resist
longitudinal separation in service. Barbs or hooks on the second
stent 40 and/or an frustoconical proximal part 42 help to resist
such longitudinal separation.
[0091] In another example of the present invention a bifurcated
endoluminal prosthesis 50 as shown in FIG. 5 includes a bifurcated
stent comprising a proximal portion 52 which tapers radially
inwardly from its proximal end 54 to its distal end 56, and first
and second transversely spaced frustoconical distal portions 58, 60
which are secured to the distal end 56 of the proximal portion 52;
the proximal portion 52 is covered with a tubular graft layer of a
biocompatible fabric 62.
[0092] In use the prosthesis is delivered percutaneously or by "cut
down" methods to an artery in juxtaposition with an arterial
bifurcation; blood can flow through the frustoconical proximal
portion 52 into each of the branched arteries through the first and
second distal frustoconical portions 58, 60. If a prosthesis is
required in one or both of the branched arteries, a separate
prosthesis comprising a stent of the type shown in FIG. 1b referred
to above covered with fabric can be connected to the bifurcated
prosthesis 50 by inserting and re-expanding the proximal end of
such a separate prosthesis in one or both of the distal
frustoconical portions 58, 60 of the prosthesis 50 for engagement
therein.
[0093] Another variant of the present invention is shown in FIG. 6
which shows a bifurcated endoluminal prosthesis 70 having a
proximal portion 72 which is secured at its distal end 74 to two
transversely spaced frustoconical intermediate portions 76, 78.
[0094] One of said frustoconical intermediate portions 76 is
secured at its distal end to an elongate distal portion 80. The
proximal end 82 of the proximal portion 72 is flared radially
outwards towards its proximal end 82 to engage the intraluminal
surface of the host blood vessel in service. Save for this flared
portion, the entire endoprosthesis is covered with a fabric graft
layer as shown in FIG. 6; said graft layer is carried externally of
the wire skeleton and is folded over the distal extremity 84 of the
other frustoconical intermediate portion 78 to form an internal
lining in said other frustoconical immediate portion 78.
[0095] Said other frustoconical intermediate portion 78 constitutes
a female cooperating portion in accordance with the present
invention which is adapted to receive a male engaging portion of
another prosthesis as indicated at 86 in FIG. 6. Said other
prosthesis 86 includes a frustoconical proximal portion 88 which
constitutes the male engaging portion and an elongate distal
portion 90. The whole of the other prosthesis 86 is covered with a
fabric graft layer as shown in FIG. 6. In service, the male
engaging portion 88 of the other prosthesis 86 is entered into and
engaged with the female cooperating portion 78 of the bifurcated
prosthesis 70 in situ in the manner herein before described. The
fabric layer on the male engaging portion 88 butts face-to-face on
the folded over portion of the fabric layer disposed internally of
the female cooperating portion 78 to form a substantially
blood-tight seal therewith.
[0096] Yet another example of the present invention is shown in
FIG. 7 in which a bifurcated endoluminal prosthesis 91 has a
generally cylindrical proximal portion 92; said proximal portion 92
is connected at its distal end 93 to an elongate, generally
cylindrical distal portion 94. Said proximal portion 92 is also
connected at its distal end 93 to a generally cylindrical
intermediate portion 95 which is secured in transversely spaced
relation to the elongate distal portion 94. Said cylindrical
intermediate portion 95 constitutes a female engaging portion which
is adapted to receive a generally cylindrical male engaging portion
of a second elongate prosthesis (not shown). The male engaging
portion is equipped with circumferentially spaced external barbs to
engage in the female cooperating portion in service. As shown in
FIG. 7, the whole of the bifurcated prosthesis 91 is covered with
an external fabric graft layer save for a flared portion 96 towards
the proximal end 97 of the proximal portion 92.
[0097] Referring to FIGS. 8(a)-8(f), an exemplary embodiment of a
delivery system according to the present invention will be
described. This system is used to deploy the bifurcated stent 10
when it is covered with a fabric graft layer to create an
endoluminal prosthesis. Introducer 100 includes outer sheath 101.
Outer sheath 101 is a cylindrical tube adapted to be inserted
either percutaneously or by "cut-down" procedures into the
vasculature from an entry point to the bifurcation site where the
prosthesis is to be deployed.
[0098] Housed within outer sheath 101 is proximal portion pusher
102. Proximal portion pusher 102 is a cylindrical tube having an
outside diameter smaller than the inside diameter of outer sheath
101. Proximal portion pusher 102 is preferably slidable throughout
the length of outer sheath 101.
[0099] Disposed within proximal portion pusher 102 is distal
portion pusher 103. Distal portion pusher 103 is a cylindrical tube
slidably contained within distal portion pusher 102. Distal portion
pusher 103 is preferably adapted to slide throughout the entire
length of proximal portion pusher 102.
[0100] Disposed within distal portion 103 is balloon catheter 104.
Balloon catheter 104 is adapted to slide within distal portion
pusher 103. At the leading end 105 of balloon catheter 104 is nose
cone 106. Balloon 107 is attached to balloon catheter 104 between
nose cone 106 and proximal end 115 of proximal portion pusher
102.
[0101] As shown in FIG. 8(g), which is a cross-sectional view of
balloon catheter 104 in the direction A-A of FIG. 8(f), balloon
catheter 104 has a guide wire conduit 104a. Guide wire conduit 104a
extends throughout the length of balloon catheter 104 for passing a
guide wire (not shown) through introducer 100. In the illustrated
embodiment, balloon catheter 104 also includes injection orifice
109 and an injection conduit 109a. Injection conduit 109a connects
injection orifice 109 to an injection site 108 at or near the
distal end of balloon catheter 104 as shown in FIG. 8(e).
Radiopaque liquid may be injected into injection site 108, through
injection conduit 109a, out injection orifice 109, and into the
vasculature to monitor deployment of the prosthesis.
[0102] Also in the illustrated embodiment of FIGS. 8(f) and 8(g),
balloon catheter 104 has an inflation orifice 110 located at a
point where balloon 107 is attached to balloon catheter 104. A
balloon inflation conduit 110a connects balloon inflation orifice
110 to balloon inflation site 111 (FIG. 8(e)). Balloon 107 may be
inflated and deflated from balloon inflation site 111 during
delivery of the prosthesis.
[0103] In an alternative embodiment illustrated in FIG. 9, seals
150, 151 may be disposed around the distal ends 160, 161 of outer
sheath 10 and proximal portion pusher 102. Seals 150, 151 may be
formed of silicone tubes.
[0104] FIG. 10(a) shows an alternative embodiment of introducer
100. As shown in FIG. 10(a), wings 112 and 113 are provided at the
distal end of introducer 100. Wing 112 is connected to proximal
portion pusher 102, and wing 113 is connected to outer sheath 101.
Wings 112 and 113 indicate the rotational orientation of proximal
portion pusher 102 and outer sheath 101, respectively. This in turn
indicates the orientation of proximal portion 12 within outer
sheath 101 and distal portion 16 within proximal portion pusher
102. Wings 112 and 113 in the illustrated embodiment are also
provided with holes 112a and 113a.
[0105] As shown in FIG. 10(b), a rod 128 or other fixation device
may be attached to wings 112 and 113 using e.g. bolts through holes
112a and 113a secured by wing nuts 129 or other securing means. Rod
128 prevents relative movement of proximal portion pusher 102 and
outer sheath 101. Wings may also be provided on distal portion
pusher 103 and used to secure distal portion pusher 103 to either
proximal portion pusher 102 or outer sheath 101 using a fixation
device as described above.
[0106] Also shown in FIG. 10(a) as part of introducer 100 is
hemostasis valve 114. Hemostasis valve 114 is connected to distal
portion pusher 103 and acts as a simple seal around balloon
catheter 104. Although it prevents fluid loss, hemostasis valve 114
allows balloon catheter 104 to slide within distal portion pusher
103. Alternatively, a Touhy-Borst valve (not shown) may be used
instead of hemostasis valve 114. The Touhy-Borst valve is a device
that may be manually tightened over balloon catheter 104. Lightly
tightening such a valve permits balloon catheter 104 to slide;
firmly tightening such a valve clamps balloon catheter 104 in
place.
[0107] In use, the prosthesis must first be loaded into introducer
100. Outer sheath 101 is first removed from introducer 100. Balloon
catheter 104 is then threaded through distal portion 16 and
proximal portion 12 of the prosthesis. The prosthesis is then
cooled to a temperature of approximately 10.degree. C. or below and
radially compressed. For this purpose, the prosthesis may be
immersed in cold water. The prosthesis should preferrably remain in
the water during the loading operation.
[0108] As supporting stent 10 is compressed beneath the fabric
covering of the prosthesis, excess fabric is produced. This excess
fabric may simply be pinched together and laid over the compressed
prosthesis in longitudinal folds.
[0109] Distal portion 16 of the prosthesis in the radially
compressed state is then inserted into proximal portion pusher 102.
Outer sheath 101 is then pulled over proximal portion 12 of the
prosthesis and over proximal portion pusher 102. A thread (not
shown) may be attached to the proximal end of proximal portion 12
of the prosthesis and threaded through outer sheath 101. This
thread may then be used to pull proximal portion 12 through outer
sheath 101. During the loading process, it is important to keep
proximal portion 12 and distal portion 16 of the prosthesis
properly aligned with outer sheath 101 and proximal portion pusher
102. Marks may be placed on the outside of outer sheath 101 and
proximal portion pusher 102 to ensure proper alignment.
[0110] Referring again to FIG. 8(f), the prosthesis is inserted
such that the outer surface of proximal portion 12 contacts and is
radially restrained by outer sheath 101, and the outer surface of
distal portion 16 contacts and is radially restrained by proximal
portion pusher 102. End 115 of proximal portion pusher 102
longitudinally engages proximal portion 12 of the prosthesis as
shown in FIG. 8(f).
[0111] Balloon catheter 104 is positioned such that nose cone 106
just clears proximal end 117 of outer sheath 101. The introducer is
now in condition for insertion into the patient.
[0112] Referring to FIG. 11, introducer 100 is passed through an
entry point (not shown) either in the patient's skin (percutaneous
operation) or into the vasculature itself which has been surgically
exposed ("cut-down" operation). Introducer 100 is inserted over a
guide wire 170 into the vasculature from the entry point to the
desired delivery location at an angeological bifurcation.
[0113] In the aorta, introducer 100 is positioned such that end 117
of outer sheath 101 is approximately level with renal arteries 180
as shown in FIG. 11. Balloon catheter 104 is then extended while
maintaining outer sheath 101 in a fixed position. Balloon catheter
104 in this embodiment is extended until distal end 105 of nose
cone 106 is approximately 35 mm above the proximal tip 117 of outer
sheath 101. Then, while maintaining proximal portion pusher 102 in
a fixed position, outer sheath 101 is withdrawn until the proximal
tip of the prosthesis is level with proximal tip 117 of outer
sheath 101. It will be noted that balloon catheter 104 does not
move while outer sheath 101 is so withdrawn.
[0114] Introducer 100 is then repositioned to place the prosthesis
in the desired deployment location. Proper placement may be
facilitated with the use of radiopaque markers ad described above.
Balloon catheter 104 is then extended such that balloon 107 is
above renal arteries 180. Balloon 107 is then inflated to occlude
the aorta as shown in FIG. 12.
[0115] While maintaining proximal portion pusher 102 in a fixed
position, outer sheath 101 is withdrawn until the proximal end of
the prosthesis emerges from outer sheath 101 as shown in FIG. 13.
Using a radiopaque marker 120 disposed on proximal end of the
prosthesis, the introducer is rotated until proper alignment of the
prosthesis is obtained. In the illustrated embodiment, radiopaque
marker 120 is a platinum wire twisted around an apex of the
prosthesis in a "V" shape. To ensure proper alignment, the stent
should be rotated until only the profile of the V is seen and shows
up as a straight line rather than a "V".
[0116] Outer sheath 101 is further withdrawn while maintaining
proximal portion pusher 102 fixed until proximal portion 12 is
fully deployed from the end of outer sheath 101, and the
frustoconical portion 18 of the prosthesis just clears end 117, as
shown in FIG. 14.
[0117] Balloon 107 is then deflated to allow blood to flow through
proximal portion 12 and out frustoconical portion 18 of the
prosthesis. Balloon 107 is withdrawn into the prosthesis until the
distal end 118 of nose cone 106 is just above the proximal end of
the prosthesis. Balloon 107 is then inflated to seat the
prosthesis, which may be provided with barbs (not shown) at its
proximal end, against the wall of the aorta, as shown in FIG.
15.
[0118] Distal portion pusher 103 is then maintained in a fixed
position while outer sheath 101 is withdrawn. Once outer sheath 101
has been withdrawn to the point at which proximal end 117 of outer
sheath 101 is flush with proximal end 115 of proximal portion
pusher 102, both outer sheath 101 and proximal portion pusher 102
are withdrawn, still maintaining distal portion pusher 103 in a
fixed position. Outer sheath 101 and proximal portion pusher 102
are withdrawn until distal portion 16 of the prosthesis is deployed
clear of proximal end 116 of distal portion pusher 103 as shown in
FIG. 16. Balloon 107 is slowly deflated to allow blood flow to be
established through the proximal portion 12 of the prosthesis and
out through frustoconical portion 18. Balloon 107 may be used to
model distal portion 16 of the prosthesis as necessary by inflating
balloon 107 where needed to expand distal portion 16. Balloon 107
is then deflated, and introducer 100 is withdrawn from the
vasculature, leaving the guide wire 170 in place, as shown in FIG.
17.
[0119] FIG. 21(a) illustrates an exemplary second introducer 300
used for deploying second distal part 44. Second introducer 300 of
the illustrated embodiment comprises cylindrical outer sheath 301
and female Luer lock assembly 310. Second introducer 300 also has
hemostasis valve 361 contained within a hub 362 thereof. Cartridge
311 shown in FIG. 21(b) is adapted to be attached to second
introducer 300. Cartridge 311 has threaded male Luer lock assembly
312 provided on its proximal end. Cartridge 311 has outer tube 313
which houses inner tube 314.
[0120] In use, a thin-walled tube (not shown) is first threaded
through distal portion 44. This tube serves as a guide wire guide,
allowing a guide wire to be threaded straight through distal
portion 44 as discussed below. Distal portion 44 containing the
thin-walled tube is then cooled, radially compressed, and inserted
into inner tube 314 of cartridge 311 in a manner similar to that
described for inserting the bifurcated prosthesis into proximal
portion pusher 102 and outer sheath 101. When distal portion 44 has
been loaded into inner tube 314 of cartridge 311, the thin-walled
tube serving as a guide wire guide extends out both ends of
cartridge 311.
[0121] A guide wire 171 is then inserted into the vasculature to
the bifurcation site and through distal stent portion 12 as shown
in FIG. 18. A dialator 359 (FIG. 21(c)) having an outer diameter
slightly less than the inner diameter of second introducer 300 is
then inserted into second introducer 300 such that tapered end 360
extends out end 320 of second introducer 300. End 360 of dialator
359 has a hole therein that is just slightly larger than guide wire
171 and tapers gradually outward from the hole to the outer
diameter of dialator 359.
[0122] Second introducer 300 is then inserted into the vasculature
over guide wire 171 by passing guide wire 171 into and through
dialator 359. Dialator 359 with tapered end 360 provides a smooth
transition within the blood vessel from the diameter of guide wire
171 to the diameter of second introducer 300. Second introducer 300
is maneuvered such that outer sheath 301 is inside frustoconical
portion 18 of proximal portion 12 by at least 20 mm in this
embodiment, as shown in FIG. 19. Dialator 359 is then removed from
second introducer 300 and from the vasculature and is
discarded.
[0123] Cartridge 311 is then passed over guide wire 171 by passing
guide wire 171 through the thin-walled guide wire guide within
distal portion 44 contained in cartridge 311. The guide wire guide
is then removed and discarded.
[0124] Cartridge 311 is then lockingly engaged with introducer 300
by mating male Luer lock assembly 310 with female Luer lock
assembly 312. Such locking engagement prevents relative movement of
cartridge 311 and introducer 300. Preventing relative movement
lends stability and reliability to the insertion process that has
not heretofore been achieved.
[0125] A pusher 315 is then inserted into inner tube 314 of
cartridge 311 such that proximal end 317 of pusher 315
longitudinally contacts a distal end of distal portion 44 within
inner tube 314. Pusher 315 pushes distal portion 44 through
cartridge 311 and into outer sheath 301 of introducer 300. Distal
portion 44 is pushed through outer sheath 301, which remains in a
fixed position, until distal portion 44 is at proximal end 320 of
outer sheath 301 (see FIG. 19). Again, radiopaque markers 120 may
be used to align distal portion 44 properly with proximal portion
12.
[0126] Pusher 302 is held firmly in place, and outer sheath 301 is
withdrawn approximately 2 cm. This deploys frustoconical part 42 of
distal part 44 inside the frustoconical part 18 as shown in FIG.
19. The outer surface of frustoconical part 42 engages the inner
surface of frustoconical part 18 such that distal portion 44 is
connected to proximal portion 12 to resist longitudinal
separation.
[0127] Outer sheath 301 may then be withdrawn while maintaining
pusher 302 in a fixed position to fully deploy distal portion 44,
as shown in FIG. 20. If necessary, balloon catheter 104 may be
inserted through sheath 301 in order to model distal portion 44.
Introducer 301 and guide wires 170, 171 are then removed from the
vasculature and the entry points are closed.
[0128] The delivery apparatus and method described above are
particularly useful in treating an abdominal aortic aneurysm with a
bifurcated prosthesis according to the present invention. Other
diseases and alternative embodiments of the prosthesis and delivery
method will now be described.
[0129] In the case of an abdominal aortic aneurysm confined to the
aorta and not extending far enough to affect the iliac arteries, a
straight (i.e. non-bifurcated) stent may be used. Preferably, for
such application, the straight stent comprises a composite of at
least two axially aligned stent segments. Two embodiments of such
straight stents are described herein, each comprising axially
aligned stent requests, each of the requests comprising one or more
adjacent hoops, perpendicular to a common axis, and each hoop being
formed of wire in a sinuous or zigzag configuration with some or
all of the juxtaposed apices in adjacent hoops secured to one
another.
[0130] First, referring to FIG. 22, straight stent 400 comprises
proximal stent portion (or segment) 401, distal stent portion 402,
and an intermediate portion 403.
[0131] Proximal portion 401 is a ring formed of a number of
longitudinally spaced hoops 20 as described in connection with the
formation of stent 10 above. In the illustrated embodiment, two
hoops 20 are used, each hoop 20 having a unit width.
[0132] Distal portion 402 is also a ring formed of longitudinally
displaced hoops 20 in the manner described above. Distal ring 402
has two hoops 20 of unit width in the illustrated embodiment.
[0133] Intermediate portion 403 of straight stent 400 is formed of
biocompatible woven fabric such as, for example, a plain woven
fabric made from 30 or 40 denier polyester. In this embodiment,
intermediate fabric section 403 does not cover a stent. Fabric
portion 403 is attached at its proximal and distal ends to the
proximal and distal stent portions, respectively, by stitching, for
example, with 0.003 inch polypropylene filaments around apices 22
of the stent portions. Other than such connections at its
longitudinal ends, intermediate fabric section 403 is unsupported
by any stent.
[0134] The second embodiment of a straight stent that may be used
according to this invention is illustrated in FIG. 23. Straight
stent 450 includes stent portion 451, constructed of wire loops as
described above with reference to stent portions 401 and 402. Stent
portion 451 is partially covered by fabric 452. In this embodiment,
fabric portion 451 covers and is supported by stent 451, whereas
with stent 400, the fabric portion 403 is not supported by a
stent.
[0135] To treat an abdominal aortic aneurysm that does not extend
down over the walls of the iliac arteries, as shown in FIG. 24(a),
straight stent 400 (or 450) is disposed as illustrated in FIG. 26.
Proximal stent portion 401 engages the inner walls of the aorta
above the aneurysm. Distal stent portion 402 engages the inner wall
of the aorta below the aneurysm. Intermediate fabric portion 403
extends across the aneurysm, providing a strong, stable lumen for
blood flow through the aorta.
[0136] FIG. 28 illustrates the delivery apparatus used to implant
straight stent 400 in the vasculature. This apparatus is very
similar to that described above for the delivery system to be used
with the bifurcated stent or prosthesis. Accordingly, like
reference numerals refer to the same components.
[0137] In the introducer 410 shown in FIG. 28, proximal portion
pusher 102 engages proximal stent portion 401. Distal portion
pusher 103 engages distal stent portion 402.
[0138] In use, straight stent 400 is first charged into the
introducer by cooling it to temperatures below 10.degree. C.,
radially compressing it, and inserting it within outer sheath 101,
as described above in connection with the bifurcated stent or
prosthesis. The remainder of introducer 410 is also assembled as
described in connection with introducer 100.
[0139] Introducer 410 is passed through an entry point (not shown)
over guide wire 411 as shown in FIG. 24(a). This insertion may be
accomplished using percutaneous or cut-down techniques. Introducer
410 is then inserted to the desired delivery location.
[0140] In the aorta, introducer 410 is positioned and balloon 107
is inflated above the renal arteries in the same manner as
described above in connection with the bifurcated stent and as
illustrated in FIG. 24(a).
[0141] While maintaining proximal portion pusher 102 in a fixed
position, outer sheath 101 is withdrawn until proximal portion 401
of stent 400 emerges from outer sheath 101 as shown in FIG. 24(b).
Using a radiopaque marker 420 disposed on the proximal end of the
proximal portion 401, stent 400 is optimally aligned within the
aorta. Outer sheath 101 is further withdrawn until proximal portion
401 emerges therefrom, as shown in FIG. 25. Outer sheath 101 is
then further withdrawn until it is flush with proximal portion
pusher 102. Then both outer sheath 101 and proximal portion pusher
102 are withdrawn while maintaining distal portion pusher 103 in a
fixed position. Distal portion 402 is thus deployed from the end of
outer sheath 101, as shown in FIG. 26.
[0142] Balloon 107 is then deflated and withdrawn inside proximal
portion 401 where balloon 107 is re-inflated to seat the stent 400,
as shown in FIG. 27. Balloon 107 is then withdrawn, along with the
introducer 410 as described above, and the entry point is
closed.
[0143] FIG. 29 illustrates the apparatus used to deploy straight
stent 450, shown in FIG. 23, of the present invention. This
apparatus is very similar to that described above for the delivery
system to be used with the bifurcated stent or prosthesis.
Accordingly, like reference numerals refer to the same
components.
[0144] Proximal portion pusher 102 in this embodiment is glued to
distal portion pusher 103 such that ends 115 and 116 are flush.
These flush ends are adapted to engage stent 450 within outer
sheath 101.
[0145] In use, straight stent 450 is first charged into introducer
490 by cooling it to temperatures below 10.degree. C., radially
compressing it, and inserting it within outer sheath 101, as
described above in connection with the bifurcated stent or
prosthesis. The remainder of introducer 490 is also assembled as
described in connection with introducer 100.
[0146] Introducer 490 is passed through an entry point (not shown)
over a guide wire 411 as shown in FIG. 30. This insertion may be
accomplished using percutaneous or cut-down techniques. Introducer
490 is then inserted to the desired delivery location.
[0147] In the aorta, introducer 490 is positioned and balloon 107
is inflated above the renal arteries in the same manner as
described above in connection with the bifurcated stent and as
illustrated in FIG. 31.
[0148] While maintaining attached proximal portion pusher 102 and
distal portion pusher 103 in a fixed position, outer sheath 101 is
withdrawn until proximal portion 451 of stent 450 emerges from
outer sheath 101 as shown in FIG. 32. Using a radiopaque marker 420
disposed on the proximal end of the proximal portion 451, stent 450
is optimally aligned within the aorta. Outer sheath 101 is then
completely withdrawn until stent 450 is deployed into the aorta as
shown in FIG. 33.
[0149] Balloon 107 is then deflated and withdrawn inside proximal
portion 451 where balloon 107 is re-inflated to seat the stent 450,
as shown in FIG. 34. Balloon 107 is then withdrawn, along with the
introducer 490 as described above, and the entry point is
closed.
[0150] The angeological disease of occlusion is the blockage of an
artery resulting from a buildup or clot of soft thrombus. There are
two types of occlusions that can occur at the aorta-iliac
bifurcation. The first is infrarenal occlusion. In this case, the
blockage extends in the aorta from just below the renal arteries
into the iliac arteries. The second type is an occlusion that is
limited to the immediate area of the bifurcation.
[0151] To treat an infrarenal occlusion, a canalization is first
made through the thrombus by methods known in the art. A bifurcated
endoluminal prosthesis according to the present invention is then
implanted at the bifurcation site to provide an unobstructed lumen
extending from the aorta into each of the iliac arteries. Blood can
thus flow freely from the aorta to the iliac arteries.
[0152] The bifurcated endoluminal prosthesis according to the
present invention that is used to treat an occlusion must be fabric
covered. This is necessary to prevent embolization from the
thrombus remaining on the wall of the recanalized artery.
[0153] An occlusion at the bifurcation is treated by recanalizing
the artery as above. A bifurcated endoluminal prosthesis according
to the present invention may be implanted at the bifurcation.
Because the occlusion is limited to the immediate bifurcation site,
however, the proximal portion of the prosthesis may be shorter than
that discussed above.
[0154] To implant the bifurcated endoluminal prosthesis to treat
both types of occlusion, the delivery system comprising introducer
100 discussed above for delivering the bifurcated endoluminal
prosthesis to treat an abdominal aortic aneurysm is used. The same
delivery method discussed above for implanting the bifurcated
endoluminal prosthesis to treat abdominal aortic aneurysms is used
to implant the device to treat the occlusion.
[0155] Using the method and apparatus of this invention to treat
occlusion provides an unobstructed lumen through which blood can
flow from the aorta to the iliac arteries.
[0156] The angeological disease of stenosis is a narrowing of an
artery caused by a buildup of hard calcified plaque. This is
usually caused by a buildup of cholesterol. To treat such an
angeological disease, angioplasty is performed on the plaque
according to methods well known in the art. The bifurcated
endoluminal stent according to the present invention is then
implanted at the bifurcation site. This stent is the same as that
described above for treatment of an abdominal aortic aneurysm. To
treat the stenosis, however, it is not necessary to cover the stent
with a fabric, thus creating a prosthesis. Because restenosis is
rare at the bifurcation site, there is no need to isolate the blood
flowing in the lumen from the walls of the arteries.
[0157] The delivery system used to implant the bifurcated
endoluminal stent used to treat stenosis is the same as that
illustrated in FIG. 8 except that balloon 107 is not required.
Because there is no fabric around the stent to be affected by blood
flow in the arteries and cause migration of the bifurcated stent,
it is not necessary to block the blood flow with the balloon.
Otherwise, the delivery system for implanting the bifurcated stent
to treat stenosis is the same as that for implanting the bifurcated
prosthesis to treat abdominal aortic aneurysm.
[0158] Similarly, with the exception of the steps involving
inflation of balloon 107 to block blood flow, the method of
delivering the bifurcated endoluminal stent to treat stenosis is
the same as that described above for delivering the bifurcated
endoluminal prosthesis to treat abdominal aortic aneurysm.
* * * * *