U.S. patent application number 11/625755 was filed with the patent office on 2007-08-02 for intraluminal grafting system.
This patent application is currently assigned to ENDOVASCULAR TECHNOLOGIES, INC.. Invention is credited to Steven G. Baker, Alec A. Piplani, Dinah B. Quiachon, Wesley D. Sterman, Ronald G. Williams.
Application Number | 20070179591 11/625755 |
Document ID | / |
Family ID | 34199309 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070179591 |
Kind Code |
A1 |
Baker; Steven G. ; et
al. |
August 2, 2007 |
INTRALUMINAL GRAFTING SYSTEM
Abstract
An intraluminal grafting system having a delivery catheter
comprising a flexible elongate tubular member having proximal and
distal extremities and a capsule mounted on the distal extremity of
the tubular member and including a graft disposed within the
capsule. The graft is comprised of a tubular body configured to be
secured to a blood vessel by a self expanding attachment system.
The attachment system comprises a generally sinusoidal wire frame
having apices which extend longitudinally outward from the end of
the tubular body apices which are secured within the tubular body.
Both the protruding apices and the base apices are formed with
helices which bias the attachment system radially outward. The
attachment system further includes a plurality of lumen piercing
members that are oriented in a responsive relationship to the
radially outward bias of the attachment system. Furthermore, the
graft may be configured with a plurality of synthetic fiber tufts
secured to the outer surface of the tubular body to facilitate
sealing the graft within the vessel. The graft may also include a
plurality of crimps formed in the tubular body of the graft.
Inventors: |
Baker; Steven G.;
(Sunnyvale, CA) ; Quiachon; Dinah B.; (San Jose,
CA) ; Piplani; Alec A.; (Mountain View, CA) ;
Sterman; Wesley D.; (San Francisco, CA) ; Williams;
Ronald G.; (Menlo Park, CA) |
Correspondence
Address: |
FULWIDER PATTON LLP
HOWARD HUGHES CENTER
6060 CENTER DRIVE, TENTH FLOOR
LOS ANGELES
CA
90045
US
|
Assignee: |
ENDOVASCULAR TECHNOLOGIES,
INC.
3200 Lakeside Drive
Santa Clara
CA
95054
|
Family ID: |
34199309 |
Appl. No.: |
11/625755 |
Filed: |
January 22, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09686264 |
Oct 10, 2000 |
7166125 |
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11625755 |
Jan 22, 2007 |
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08485481 |
Jun 7, 1995 |
6221102 |
|
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11625755 |
Jan 22, 2007 |
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08109162 |
Aug 19, 1993 |
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11625755 |
Jan 22, 2007 |
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07553530 |
Jul 13, 1990 |
5275622 |
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11625755 |
Jan 22, 2007 |
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Current U.S.
Class: |
623/1.23 ;
623/1.28; 623/1.36 |
Current CPC
Class: |
A61F 2220/0016 20130101;
A61F 2220/0075 20130101; A61F 2220/005 20130101; A61F 2/04
20130101; A61F 2/07 20130101; A61F 2002/3008 20130101; A61F
2002/30451 20130101; A61B 17/11 20130101; A61F 2230/0054 20130101;
A61F 2220/0058 20130101; A61F 2250/0098 20130101; A61M 2025/1068
20130101; A61F 2/89 20130101; A61F 2/848 20130101; A61M 25/10
20130101; A61F 2/958 20130101; A61F 2002/8486 20130101; A61F 2/82
20130101; A61F 2002/075 20130101 |
Class at
Publication: |
623/001.23 ;
623/001.36; 623/001.28 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1-4. (canceled)
5. A system for repairing vasculature, comprising: a catheter
assembly; a graft assembly including a graft body and a plurality
of generally sinusoidal wire frames attached to the graft body, at
least one wire frame including a plurality of lumen piercing
members associated therewith, the plurality of lumen piercing
members being staggered longitudinally with respect to the wire
frame.
6. The system of claim 5, wherein the catheter assembly is sized
and shaped to receive the graft assembly.
7. The system of claim 6, wherein the catheter assembly includes a
balloon catheter.
8. The system of claim 7, wherein the wire frames are
self-expanding.
9. The system of claim 8, wherein the lumen piercing members have a
length sufficient to pierce but not puncture through a wall of a
vessel.
10. The system of claim 9, wherein the wire frames include helical
coils forming apices.
11. The system of claim 10, wherein the lumen piercing members
include hook-like elements.
12. The system of claim 11, wherein the hook-like elements are in
the form of a barb.
13. The system of claim 11, wherein the hook-like elements are in
the form of spine-like ribbon.
14. The system of claim 5, wherein at least one frame assembly
includes staggered apices.
Description
[0001] This application is a continuation-in-part of application
Ser. No. 109,162 filed Aug. 19, 1993, which is a divisional of
application Ser. No. 553,530 filed Jul. 13, 1990, now U.S. Pat. No.
5,275,622, which is a continuation-in-part of application Ser. No.
166,093 filed on Mar. 9, 1988, now U.S. Pat. No. 5,104,399, which
is a continuation-in-part of application Ser. No. 940,907 filed on
Dec. 10, 1986, now U.S. Pat. No. 4,787,899, which is a continuation
of application Ser. No. 559,935 filed on Dec. 9, 1983, now
abandoned. The contents of each of these applications are hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] This application relates to endovascular grafting apparatus,
system and method and devices for use therewith.
[0003] The state of the art is described in the background of the
invention in U.S. Pat. No. 4,787,899.
SUMMARY OF THE INVENTION
[0004] In general, it is an object of the present invention to
provide an endovascular grafting apparatus, system and method and
devices for use therewith which overcome the disadvantages of the
prior art apparatus, systems and devices.
[0005] Another object of the invention is to provide an apparatus
and system of the above character which utilizes a pusher rod
assembly which is constrained so that relatively great forces can
be applied by the pusher rod assembly.
[0006] Another object of the invention is to provide an apparatus
and system of the above character in which the capsule is flexible
so that it can negotiate bends in the vessels of a patient.
[0007] Another object of the invention is to provide a grafting
apparatus and system which utilizes a flexible capsule which can
contain a graft with hook-like elements without any danger of the
hook-like elements penetrating the capsule.
[0008] Another object of the invention is to provide an apparatus
and system of the above character in which the graft automatically
springs into an open or expanded position when it is released from
the capsule.
[0009] Another object of the invention is to provide an apparatus,
system and method of the above character in which a pushing force
is applied to the distal extremity of the balloon for advancing a
graft out of the capsule.
[0010] Another object of the invention is to provide an apparatus
and system of the above character in which a fixed wire or an
over-the-wire guide wire system can be used.
[0011] Another object of the invention is to provide an apparatus
and system of the above character in which the graft can be
compressed to a very small size in a flexible capsule.
[0012] Additional objects and features of the invention will appear
in the following description in conjunction with the accompanying
drawings.
[0013] Another feature of the present invention is a novel
attachment system that comprises a sinusoidal wire frame and
V-shaped lumen piercing members. The sinusoidal frame has two ends
and alternating base apices and protruding apices. The protruding
apices protrude outward and are mounted onto the graft to extend
outward past the end of the graft. The base apices are oriented
inside the lumen of the graft and points inward from the end of the
graft. The portion of the wire frame connecting the protruding
apices to the base apices are struts.
[0014] In one embodiment, the two ends of the wire frame are welded
together to obtain circular continuity of the wire frame. In
another embodiment, the wire frame has one additional protruding
apex and the ends of the wire frame terminate in helices generally
aligned with the base helices. The frame is mounted by overlapping
the two ends of the wire including a pair of protruding apices
adjacent the end. The wire frame is sewn to the body of the graft
at various points over the entire wire frame. The lengths of the
struts may be adjusted to stagger the apices so that the profile of
the wire frame and the graft can be minimized to fit into a smaller
delivery capsule.
[0015] In addition to the wire frame, the attachment system further
includes a plurality of lumen piercing members affixed to the
struts. The lumen piercing members are configured to protrude
radially outward from the attachment system to engage the lumen
wall of a blood vessel and secure the graft in place to prevent
migration of the graft along the blood vessel. The lumen piercing
member of one embodiment includes a wire arm that has an outwardly
protruding hook constructed of stainless steel wire. The hooks are
aligned with and welded to the struts of the wire frame.
[0016] Another embodiment of the lumen piercing members eliminates
the need for welds to secure the lumen piercing members to the
graft. Each lumen piercing member is bent into a V-shape and each
have an apex and two arms that extend in a direction parallel to
the struts of the wire frame. The arms terminate in radially
outward protruding hooks that are configured to engage the wall of
the vessel. The lumen piercing member is secured to the graft in
close proximity to the wire frame and is responsive to the outward
bias of the wire frame.
[0017] Another embodiment of the attachment system of the present
invention configured for use in the iliac arteries in a bifurcated
graft includes two sinusoidal wire frames that have alternating
base apices and protruding apices. Each of the iliac wire frames
have two end arms that extend longitudinally outward to engage the
iliac artery wall. The wire arms are configured as lumen piercing
members which extend as struts from the end base apices. The two
wire frames are joined together by overlying the end base apex of
one of the wire frames with the end base apex from the other wire
frame such that each of the wire arms extend parallel to an
adjacent strut. The end arms are twisted around the adjacent struts
and bent behind the protruding strut that is integrally connected
to the adjacent strut. The ends of the lumen piercing member is
hook-like to securely engage the vessel wall. The hooks are secured
to the vessel wall when an additional radially outward force
presses the vessel into the lumen wall, such as from a deployment
balloon.
[0018] Another feature of the present invention includes a device
to substantially eliminate leaks around the perimeter of the graft
at the ends where the attachment system engages the lumen wall. The
outside of the graft is textured with a plurality of filaments or
fibers that are spun, woven, knotted, pressed or otherwise loosely
associated to form a puffed textured filler or tuft that is sewn to
or affixed to the outside of the graft proximal to the end of the
graft. The ends of the fibers may be frayed to increase the surface
area of the tuft. Alternatively, strands of loosely spun synthetic
yarn are cross-stitched around the perimeter of the graft proximate
the attachment system.
[0019] Another feature of the present invention includes a graft
that is crimped radially along at least a portion of the length of
the graft. The crimps form a generally corrugated tubular surface
defining a plurality of radially outwardly protruding ribs that are
separated longitudinally by alternating inwardly directed folds or
pleats. The crimping occurs along the length of the graft between
the two attachment systems. The crimping may be configured over the
entire length or over only a portion of the graft.
[0020] Other features and advantages of the present invention will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, which illustrate, by
way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an isometric view of an endovascular grafting
apparatus and system incorporating the present invention.
[0022] FIG. 2 is a side elevational view partially in cross section
of a capable catheter incorporating the present invention.
[0023] FIG. 3 is a side elevational view partially in cross section
showing a balloon catheter assembly incorporating the present
invention.
[0024] FIG. 4 is a partial side elevational view in cross section
of a portion of an alternative balloon catheter assembly
incorporating the present invention showing the use of a movable
pusher button capsule of sliding over a limited range.
[0025] FIG. 5 is a side elevational view partially in cross section
of another alternative embodiment of a balloon catheter assembly
incorporating the present invention showing the use of a movable
guide wire.
[0026] FIG. 6 is a cross sectional view taken along the line 6-6 of
FIG. 5.
[0027] FIG. 7 is a side elevational view partially in cross section
of a pusher rod assembly incorporating the present invention.
[0028] FIG. 8 is a side elevational view partially in cross section
of another embodiment of a pusher rod assembly incorporating the
present invention. FIG. 9 is a cross sectional view partially in
cross section showing in combination a balloon catheter and a
pusher rod assembly and a movable guide wire.
[0029] FIG. 10 is a side elevational view of a graft incorporating
the present invention.
[0030] FIG. 11 is an enlarged isometric view showing one of the
spring attachment means utilized on the graft.
[0031] FIG. 12 is a partial enlarged view of an alternative
hook-like element utilized in the spring attachment means of FIG.
11.
[0032] FIG. 13 is an enlarged view showing another embodiment of a
hook-like element used in the spring attachment means of FIG.
11.
[0033] FIG. 14 is a side elevational view partially in cross
section showing the manner in which the graft is held in the
capsule after ejection of the proximal extremity of the graft from
the capsule.
[0034] FIG. 15 is a view similar to FIG. 14 but showing the
proximal and distal extremities of the graft outside of the capsule
with the balloon retracted so that it is within the graft and
inflated to force the distal attachment means into the vessel
wall.
[0035] FIG. 16 is an enlarged side elevational view of one strut
and lumen engaging member of FIG. 30.
[0036] FIG. 17 is a graph showing the compression and tension
forces on the strut of FIG. 16.
[0037] FIG. 18 is an isometric view of an endovascular graft
incorporating the attachment system of FIG. 30, further showing the
tufts and stitching on the outside and inside of the graft.
[0038] FIG. 19 is a plan view of the inside of an endovascular
graft cut longitudinally, showing the wire frame, separate lumen
engaging members and stitching of the attachment system.
[0039] FIG. 20 is a plan view of the outside of an endovascular
graft cut longitudinally, showing in partial hidden view the wire
frame and the separate lumen engaging members of the attachment
system and further showing the tufts attached to the outside of the
graft.
[0040] FIG. 21 is a plan view of the inside of an endovascular
graft cut longitudinally, showing the wire frame, lumen engaging
members and stitching of the attachment system.
[0041] FIG. 22 is a top plan view of an endovascular graft having
an attachment system as shown in FIG. 20, showing the pleats and
tufts of the graft secured within the vessel lumen.
[0042] FIG. 23 is an enlarged top plan view of the area shown along
curve 23 of FIG. 22.
[0043] FIG. 24 is a side elevational view of an iliac attachment
system, wherein the base apices are sewn to the end edge of a leg
of a bifurcated graft.
[0044] FIG. 25 is a side elevational view of an iliac attachment
system, wherein the base apices are sewn within a leg of a
bifurcated graft and below the end edge of the leg.
[0045] FIG. 26 is a plan view of the graft and attachment system of
FIG. 24 cut longitudinally, showing the wire frame of the iliac
attachment system having lumen engaging members.
[0046] FIG. 27 is a partial cross-sectional view of a leg of a
bifurcated graft and an iliac attachment system secured within a
vessel having an enlarged vessel wall and constricted lumen.
[0047] FIG. 28 is a partial cross-sectional view of a leg of a
bifurcated graft and an iliac attachment system secured within a
vessel having a bulge in the vessel wall.
[0048] FIG. 29 is a side elevational view of an endovascular graft
incorporating an attachment system of the present invention.
[0049] FIG. 30 is an enlarged isometric view showing one of the
spring attachment systems shown in the graft of FIG. 29.
[0050] FIG. 31 is an enlarged perspective view of a duck-billed
configured hook of a lumen engaging member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0051] In general, the endovascular grafting system is comprised of
a capsule catheter having a flexible elongate tubular member with
proximal and distal extremities and a capsule mounted on the distal
extremity of the tubular member. The capsule is generally
cylindrical in shape and is formed of a helical wraps of a metal
ribbon. Means is provided for bonding said wraps into a unitary
capsule while permitting bending of said unitary capsule. A graft
is disposed within the capsule. The graft is comprised of a tubular
member having proximal and distal ends. Hook-like attachment means
is secured to the proximal and distal ends of the tubular member
and face in a direction outwardly towards the inner wall of the
capsule. Push rod means is disposed within the capsule catheter and
engages the graft whereby upon relative movement between the push
rod means and the capsule catheter, the graft can be forced out of
the capsule.
[0052] More in particular, the endovascular grafting apparatus and
system 11 and the devices for use therein are shown in FIGS. 1-10.
This apparatus and system 11 includes a capsule catheter 12 (see
FIG. 2) which consists of a flexible elongate tubular member 16
formed of a suitable plastic material such as Nylon of a suitable
length as, for example, 40 to 100 centimeters and preferably
approximately 43 centimeters for the abdominal aortic artery and
approximately 70 centimeters for the thoracic aortic artery. The
tubular member 16 can have a suitable size such as an outside
diameter of 0.187 inches and an inside diameter of 0.125 inches.
The tubular member 16 can be produced in a certain color such as
blue. In order to make it radiopaque under x-rays, the flexible
tubular member 16 is loaded with a suitable radiopaque material
such as bismuth subcarbonate or barium sulfate. By way of example,
the flexible elongate member 16 can be compounded with
approximately 20% of the radiopaque material by weight.
[0053] An inner liner 17 is provided which is mounted within the
tubular member 16. The liner 17 is sized so that it will fit within
the tubular member 16. The liner is preferably formed of a
lubricous material such as Tefzel (ethylene tetrafluoroethylene) or
Teflon FEP (fluorinated ethylene polypropylene). It can have an
inside diameter of 0.085 inches and an outside diameter of 0.125
inches and a length as, for example, 41 centimeters which is
slightly less than that of the tubular member 16. If desired, the
inside diameter of the liner 17 can be in the range of 0.075 to
0.120 inches. The liner 17 is provided with a lumen 18 which
extends the length thereof. The liner 17 reduces the inside
diameter of the lumen 18 for a purpose hereinafter described. The
liner 17 is made of a radiation stable material so that the
catheter can be radiation sterilized. Tefzel, or Teflon FEP, which
is a polymer is such a radiation sterilizable material. The inner
liner 17 also serves to provide additional columnar strength to the
catheter 12.
[0054] A wye adapter 21 is secured to the proximal extremity of the
flexible tubular member 16. The side arm 22 of the adapter 21 has a
stop cock 23 mounted therein which is movable between open and
closed positions. The stop cock 23 is provided with a Luer fitting
24 which is adapted to be secured to a syringe which can be
utilized for injecting a dye, or medications such as a
vasodilator.
[0055] The central arm 26 of the adapter 21 is connected to a Touhy
Borst adapter 27 and includes a female part 28 that carries an
0-ring 29 which is adapted to be engaged by a protrusion 31 forming
a part of the male part 32.
[0056] The capsule catheter 12 has a capsule 36 incorporating the
present invention mounted on the distal extremity of the flexible
elongate tubular member 16. The capsule 36 when used in humans has
a diameter ranging from 4 to 8 millimeters. The flexible elongate
tubular member 16 which also serves as a shaft for advancing the
capsule 36 as hereinafter described and should have a diameter
which is less than that of the capsule and therefore has an outside
diameter ranging from 3 to 7 millimeters.
[0057] The capsule 36 is a composite structure and is formed of an
inner layer 37 and an outer layer 38. The inner layer 37 is formed
of a stainless steel ribbon 39 with the ribbon having a width of
0.150 inches and a thickness ranging from 0.002 to 0.004 inches and
preferably approximately 0.003 inches. The ribbon is spiral wound
on a mandrel (not shown) so that each wrap of the ribbon overlaps
the preceding wrap by approximately 30 to 50% of the width of the
ribbon. viewing the capsule 36 from the left hand end, the ribbon
is wrapped in a clockwise or counterclockwise direction so that the
edges 41 face distally or in the direction which is toward the
right as shown in FIG. 2 for a purpose hereinafter described. By
winding the ribbon 37 at high tension, it is possible to deform it
over the adjacent wrap which contributes to the flexibility of the
capsule and also at the same time makes it possible to provide a
capsule having a low profile. The stainless steel for the ribbon 39
can be of any suitable type, however, it has been found that it is
desirable to select a stainless steel which can be heat treated.
This enables one to wind the capsule with a ribbon in a ductile
state and heat treat the capsule after winding to obtain a
spring-like temper. One such stainless steel is 17-7 PH supplied by
Brown Metals Company of Santa Fe Springs, Calif.
[0058] In order to prevent elongation of the capsule 36 and also to
prevent one wrap separating from another of the inner layer 37, a
plurality of elongate flexible strands 43 are provided which extend
from one end to the other of the capsule. It has been found that
the use of four strands has been sufficient with the strands being
spaced apart circumferentially by 90.degree.. The strands 43 can be
formed of a suitable material such as a Kevlar aramid fiber, 195
denier. These four strands 43 are bonded to the proximal and distal
extremities of the capsule by a suitable adhesive such as a
cyanoacrylate ester at points 44. The outer layer 38 which overlies
the strands 43 and the wrapped ribbon inner layer 37 is in the form
of a jacket formed of a suitable material such as heat shrinkable
polyethylene. This jacket can have a wall thickness ranging from
0.001 to 0.006 inches and preferably a thickness of approximately
0.004 inches. The polyethylene jacket which forms the outer layer
38 serves to contain the Kevlar strands 43 in close proximity to
the inner layers 37 and also serves to prevent elongation of the
capsule 36 while permitting the capsule to bend during use as
hereinafter described. The outer layer or jacket 38 serves also to
provide a smooth surface for the exterior of the capsule 36 by
enclosing the edges 41 of the wraps of ribbon 39. In addition, the
proximal and distal extremities of the capsule 36 are bonded
together by a solder in the regions 46 as indicated in FIG. 2. The
solder can be of a suitable type, such as a tin silver solder
comprised of 95% tin and 5% silver. When constructed in this
manner, the capsule 36 can have an inside diameter of 0.175 inches
to 0.300 inches with a nominal wall thickness of 0.0012 inches.
[0059] The capsule 36 is secured to the distal extremity of the.
flexible elongate tubular member 16 by a capsule adapter 51 of a
suitable material such as a polycarbonate. The capsule adapter 51
is secured in the proximal extremity of the capsule 36 by suitable
means, as a press fit or alternatively, in addition, by the use of
a suitable adhesive such as a cyanoacrylate ester. The other
extremity of the capsule adapter 51 is also mounted in a suitable
manner such as by a cyanoacrylate ester adhesive to the distal
extremity of the flexible elongate tubular member 16. The capsule
adapter 51 is provided with a hole 52 of a suitable diameter such
as 1/16th of an inch.
[0060] The capsule 36 made in accordance with the present invention
has a number of desirable features. It is particularly desirable
because it is flexible and can be bent through an angle of 70 to
120.degree. in a length of 8-20 centimeters. In order to prevent
hangups on the inside edges 41 of the ribbon, the inside edges are
rounded and polished, preventing damage to capsule contents during
ejection as hereinafter described. The Kevlar strands 43, which are
also contained by the outer jacket or layer 38, serve to maintain
the wrap, prevent stretching or elongation and prevent
discontinuities from being formed in the capsule during use of the
same. In addition, the Kevlar strands prevent the capsule from
being flexed beyond a predetermined angle, as, for example,
120.degree..
[0061] Thus, it can be seen that a capsule 36 has been provided
which is very flexible, yet is still very hard and has great
strength which inhibits crushing or collapsing while being bent or
flexed. In other words, it is kink resistant. It is also puncture
proof due to the use of the metal ribbon 37. The capsule 36 is
semi-radiopaque and is radiation sterilizable.
[0062] The endovascular grafting apparatus also includes a balloon
catheter assembly 61 which consists of a shaft in the form of a
flexible elongate element 62 formed of a suitable material such as
irradiated polyethylene tubing extruded to a larger diameter of
0.160 inches outside diameter and 0.090 inches inside diameter and
then reduced in size by heating and elongating the same to provide
an inside diameter of 0.020 inches and an outside diameter of 0.050
inches. However, the inside diameter can range from 0.015 to 0.025
inches and the outside diameter can range from 0.035 to 0.065
inches for a single lumen balloon catheter assembly. The single
balloon inflation lumen 63 extends the length of the catheter. The
catheter can have a suitable length as, for example, 50 to 130
centimeters. The lumen 63 can also serve as an injectate lumen and
a pusher wire lumen as hereinafter described.
[0063] A separate balloon 64 formed of suitable material such as
polyethylene is secured to the distal extremity of the flexible
elongate member 62 in a manner hereinafter described. A pusher
button 66 is provided which is formed of a suitable material such
as 300 series stainless steel. The pusher button 66 can have a
diameter ranging from 0.120 inches to 0.200 inches and preferably
an outside diameter of approximately 0.140 inches. Stainless steel
is utilized to achieve radiopacity.
[0064] The pusher button 66 is mounted on a fixed position on the
catheter shaft 62 and is spaced a predetermined distance from the
proximal extremity of the balloon 64 as, for example, a distance of
2 to 3 centimeters. The pusher button 66 is retained in this
position longitudinally of the shaft 62 by annular bulbs 67 and 68
which are formed by localized heating in those areas of the shaft
62 which causes it to expand radially in an attempt to achieve its
original size to trap the pusher button 66 in that position to the
shaft 62. Thus, it can be seen that the pusher button 66 can be
mechanically trapped in place without the use of an adhesive and
without changing the size of the lumen 63 which extends
therethrough.
[0065] An alternative embodiment in which the pusher button 66 is
movable between the proximal extremity of the balloon 64 and a
single bulb 67 is shown in FIG. 4.
[0066] A small stainless steel tube 69 is disposed within the
balloon 64 and has its proximal extremity seated within the distal
extremity of the shaft or flexible elongate member 62. The tube 69
has a suitable inside diameter such as 0.022 inches, an outside
diameter of 0.032 inches and a suitable length as, for example, 7.5
centimeters. As can be seen from FIG. 3, the tube 69 extends
through the balloon 64 and terminates in the distal extremity of
the balloon. The proximal extremity of the tube 69 is flared
slightly so that it is firmly retained within the shaft 62 when the
proximal extremity of the balloon is fused to the shaft 62 by the
use of heat. The tube 69 serves to provide stiffness to the balloon
64 of the balloon catheter assembly 61 and is provided with a lumen
71 extending therethrough through which a fluid such as a gas or
liquid can be introduced from the lumen 63 into the lumen 71 to
inflate the balloon and to thereafter deflate the balloon 64 by
withdrawing the gas or liquid. The balloon 64 can vary in diameter
from 12 to 35 millimeters in diameter and can have a wall thickness
ranging from 0.001 and 0.005 inches. The polyethylene utilized for
the balloon is irradiated to achieve an appropriate balloon size.
One balloon made in accordance with the present invention had an
outside diameter of 16 millimeters and had a wall thickness of
approximately 0.003 inches. In addition, the balloon when deflated
is twisted into a helix and heated so as to provide it with a
memory which facilitates its introduction into a vessel of a
patient as hereinafter described.
[0067] A very flexible guide wire 74 is secured to the distal
extremity of the balloon 64. The guide wire can have a suitable
diameter such as 0.052 inches in outside diameter and can have a
suitable length, as for example, 7 centimeters. The guide wire 74
can be a spring formed from wire having a suitable diameter such as
0.009 inches so that it will be radiopaque and thus readily
observable under x-rays when being used. The guide wire is provided
with a rounded tip 76 which can be formed from a suitable material
such as a tin silver solder of 95% tin and 5% silver. The solder
tip 76 has bonded therein the distal extremity of a safety ribbon
77 which extends towards the proximal extremity of the spring guide
wire 74 and is secured to the proximal extremity thereof by
suitable means such as the same tin silver solder hereinbefore
described. The guide wire 74 can range in diameter from 0.036
inches to 0.060 inches. The ribbon 77 can be formed of a suitable
material such as stainless steel and have a thickness of 0.003
inches and a width of 0.010 inches.
[0068] As can be seen from FIG. 3, the proximal extremity of the
spring guide wire 74 has been stretches longitudinally beyond the
yield point so that there is a space or interstice between each
turn of the wire forming the proximal extremity of the spring. A
plug 78 of a non-irradiated polyethylene is placed within the
proximal extremity of the spring guide wire 74 but remote from the
distal extremity of the tube 69. The plug 78 and the distal
extremity of the balloon 64 are then heated to cause the
non-irradiated polyethylene to melt and flow into the interstices
of the stretched spring 74 to bond the spring 74 to the distal
extremity of the balloon 64 and to seal the distal extremity of the
balloon so that gas cannot escape therefrom.
[0069] The guide wire 74 is easily observed using x-rays due to its
width and stainless steel composition. Since the pusher button 66
is also formed of stainless steel, it also is an easy marker to
follow. The pusher button 66 and guide wire 74 help indicate the
position of the balloon 64 because the balloon 64 is positioned
between the pusher button 66 and the guide wire 74. The balloon 64
itself can be observed under x-rays because the blood in the
patient's vessel is more opaque than the gas used for inflating the
balloon. However, increased visibility of the balloon 64 can be
obtained by inflating the balloon 64 with a diluted radiopaque
contrast solution. In addition, if desired as shown in FIG. 3, two
radiopaque bands 79 and 80 of a suitable material such as platinum
or a platinum tungsten alloy can be placed on the proximal and
distal extremities or necked-down portions of the balloon 64 to aid
in ascertaining the position of the balloon 64.
[0070] It should be appreciated that although a separate balloon 64
has been provided, if desired, an integral balloon can be provided
which is formed of the same tubing from which the flexible elongate
tubular member 62 is made. This can be readily accomplished, as is
well known to those skilled in the art, by using an additional
radiation dose for the balloon region of the tubing.
[0071] In FIGS. 5 and 6 there is shown an alternative balloon
catheter assembly 81 which utilizes a multi-lumen flexible shaft 82
having a balloon 84 secured to the distal extremity of the same.
The flexible shaft 82 is provided with a guide wire lumen 86 of a
suitable size, as for example, 0.040 inches which extends the
entire length of the shaft and through the balloon 84. It is also
provided with a balloon inflation lumen 87 of a smaller size such
as 0.010 to 0.015 inches which opens through a notched recess 90
into the interior of the balloon 84. The lumen 87 can be connected
to a suitable syringe or other device for inflating and deflating
the balloon 84. A pusher button 88 is mounted on the shaft 82 which
is held in place by a bulb 89 formed on the shaft 82. A
conventional guide wire 91 can then be inserted into the lumen 86
of the catheter assembly 81 and utilized in a conventional manner
to advance the balloon catheter into tortuous vessels. Thus it can
be seen that applicants' balloon catheter assembly 61 can be
utilized in an over-the-wire system which is commonly used in
angioplasty. The proximal and distal extremities of the balloon 84
can be fused by heat to the shaft 82 so that the balloon 84 can be
inflated and deflated. With the guide wire 91 removed the lumen 86
can be used as an injectate lumen.
[0072] The endovascular grafting apparatus also includes a pusher
rod assembly 96 which is shown in FIG. 7. It consists of a rigid
thin wall tube 97 formed of a suitable material such as stainless
steel. It has a suitable length as, for example, 21 centimeters and
has an outside diameter of 0.065 inches and an inside diameter of
0.053 inches. An elongate solid flexible wire 98 of a suitable
diameter as, for example, 0.018 inches is provided which extends
centrally into the bore 99 of the tube for the entire length of the
rigid tube 97. The wire 98 is secured by suitable means such as an
adhesive into a male Luer cap 101 mounted on the proximal end of
the tube 97.
[0073] The outside of the tube 97 is small enough so that it can
slide inside the lumen sleeve 18 of the liner 17 of the catheter
12. The bore 99 of the rigid tube 97 is large enough so that it can
receive the balloon catheter shaft 62 with the wire 98 extending
into the lumen 63 of the shaft 62. The wire 98 is long enough so
that it can extend through the balloon shaft 62 and through the
balloon 64 and the tube 69 to engage the plug 78 provided at the
distal extremity of the balloon 64. Typically, the pusher rod
assembly 96 has a total length of approximately 75 centimeters.
[0074] An alternative pusher rod assembly 106 is shown in FIG. 8
and consists of a rigid tube 107 similar to the tube 97 with a
0.018 wire 108 extending into the same and being connected to a
male Luer cap 109. A Touhy Borst 0-ring adapter 111 is secured to
the proximal extremity of the tube 107 and is provided with an
0-ring 112. A female Luer fitting 113 is mounted on the Touhy Borst
adapter 111. In use of pusher rod assembly 106, the shaft 62 of the
balloon catheter assembly 61 is threaded into the tube 106 over the
wire 108 and through the 0-ring 112. The proximal extremity of the
shaft 62 is flared slightly over the 0-ring after which the Touhy
Borst adapter 111 can be tightened to seal the 0-ring 112 around
the balloon catheter shaft 62. After certain operations are
accomplished as hereinafter described, the male Luer cap 109 and
the wire 108 attached thereto can be removed and a syringe (not
shown) can be placed on a female Luer adapter 113 to inflate the
balloon.
[0075] An alternative embodiment of a pusher rod assembly 116
cooperating with the balloon catheter assembly 81 shown in FIG. 5
is shown in FIG. 9. The pusher rod assembly 116 is comprised of a
flexible relatively rigid tubular sleeve 117 of stainless steel
which has a bore of a diameter to accommodate the shaft 82 of the
catheter assembly 81 through which the guide wire 91 extends. A wye
adapter 118 is secured to the proximal extremity of the sleeve 117.
A stop 119 is mounted in the side arm of the adapter 118 and a
Touhy Borst adapter 120 is mounted in the central arm of the
adapter 118. The guide wire 91 extends through the guide wire lumen
86 and through the wye adapter 118 and the Touhy Borst adapter 120
so that it can be readily engaged by the hand for advancing and
retracting the guide wire 91. The balloon 84 can be inflated and
deflated through the stop cock 119. By pushing on the adapter 118 a
force is applied to the pusher button 88 by the coaxial sleeve 117
for a purpose hereinafter described.
[0076] The endovascular grafting apparatus 11 also includes an
expandable intraluminal vascular graft 121 shown in FIGS. 10 and 11
for implanting in a body vessel. The graft 121 consists of a
deformable tubular member 122 which is provided with first and
second ends 123 and 124 and a cylindrical or continuous wall 126
extending between the first and second ends 123 and 124. The
continuous wall 126 can be woven of any surgical implantable
material such as a Dacron-type 56 fiber. One material found to be
satisfactory is DeBakey soft woven Dacron vascular prosthesis
(uncrimped) sold by USCI. In order to prevent unraveling of the
woven material at the ends, the ends can be melted with heat to
provide a small melted bead of Dacron on each end. The tubular
member 122 can have a suitable length as, for example, 8 to 15
centimeters with 10 centimeters being typical. The tubular member
122 can have a maximum expandable diameter ranging from 14 to 30
millimeters and a minimum diameter in a collapsed condition of
0.175 to 0.300 inches. Expandable spring means 131 is provided on
each of the first and second ends 123 and 124 of the tubular member
122 and is secured to the tubular member. The spring means serves
to yieldably urge the tubular member 122 from a first compressed or
collapsed position to a second expanded position. The spring means
131 is formed of a plurality of vees 132 with the apices 133 of the
vees 132 being formed with helical coil springs 136 to yieldably
urge the legs 137 and 138 of each of the vees 132 outwardly at a
direction at right angles to the plane in which each of the vees
lie. The spring means 131 is shown more in detail in FIG. 11 and as
shown therein, the spring means is comprised of a single piece of
wire which is formed to provide the vees 132 and also to define the
helical coil springs 136 between the legs 137 and 138. In the
construction shown in FIG. 10, it can be seen that the spring means
131 have apices lying in three longitudinally spaced-apart parallel
planes 141, 142 and 143 which are spaced with respect to the
longitudinal axis of the tubular member 122. The two ends of the
single piece of wire can be welded together in one of the legs 137
and 138 to provide a continuous spring means.
[0077] The spring means 131 is secured to the first and second ends
123 and 124 of the tubular member by suitable means such as Dacron
polyester suture material 146 which is utilized for sewing the
spring means onto the tubular member. This can be accomplished by a
sewing operation with the suture material 146 extending into and
out of the wall 126 of the tubular member and in which knots 147
are formed on each of the legs or struts 137 and 138 in such a
manner so that the apices lying in the plane 141 extend outwardly
and are spaced from the end on which they are mounted and in which
the apices lying in the plane 142 extend just beyond the outer edge
of the tubular member and in which the apices in the third plane
are positioned inwardly from the outer edge.
[0078] Hook-like elements 151 are provided on the apices lying in
planes 141 and 142 and are secured to the vees 132 in the vicinity
of the apices by suitable means such as welding. The hook-like
elements 151 can have a suitable diameter such as 0.010 to 0.14
inches and a length from 0.5 to 3 millimeters. The hook-like
elements are sharpened to provide conical tips. The hook-like
elements 151 should have a length which is sufficient for the hook
to penetrate into the vessel wall, but not through the vessel
wall.
[0079] The spring means 131 with the hook-like elements 151 secured
thereto are formed of a corrosion resistant material which has good
spring and fatigue characteristics. One such material found to be
particularly satisfactory is Elgiloy which is a
chromium-cobalt-nickel alloy manufactured and sold by Elgiloy of
Elgin, Ill. The wire can have a diameter ranging from 0.010 to
0.015 inches in diameter with the smaller diameter wire being
utilized for the smaller diameter tubular members as, for example,
12 to 15 millimeters in diameter and the larger tubular members as,
for example, those having a 30 millimeter diameter using the larger
wire sizes.
[0080] It has been found that the spring force created by the
helical coils 136 at the apices 133 is largely determined by the
diameter of the wire. The greater the diameter of the wire, the
greater the spring force applied to the struts or legs 137 and 138
of the vees. Also, the longer the distances are between the apices
lying in planes 141 and 142, the smaller the spring force that is
applied to the legs or struts 137 and 138. It therefore has been
desirable to provide a spacing between the outer extremities of the
legs or struts of approximately one centimeter, although small or
larger distances may be utilized.
[0081] The hook-like elements 151 at the proximal and distal
extremities of the graft 121 are angled at suitable angles with
respect to longitudinal axis of the tubular member 122. The
hook-like elements face towards each other to facilitate holding
the graft 121 in place in the vessel of the patient. Thus, the
hook-like elements 151 on the proximal extremity 123 are inclined
from the longitudinal axis by 55.degree. to 80.degree. and
preferably about 65.degree. toward the distal end of the graft 121
in the direction of blood flow. The hook-like elements 151 on the
distal end 124 of the graft or implant 121 are inclined from the
longitudinal axis by 30.degree. to 90.degree. and preferably
85.degree. in a direction towards the proximal end 123 and opposite
the direction of blood flow. The hook-like elements 151 serve as
attachment means at each end of the graft 121 and when implanted
oppose migration of the graft.
[0082] The helical coil springs 136 placed at the nodes or apices
133 of the vees 132 of the spring means 131 serve to facilitate
compression of the graft when it is desired to place the same
within the capsule 36 as hereinafter described. The compression of
the graft is accomplished by deformation of the coil springs 136
within their elastic limits. Placing the nodes or apices 133 in
different planes greatly aids in reducing the size to which the
graft can be reduced during compression of the same by staggering
or offsetting the hooks or hook-like elements 151. This also helps
to prevent the hook-like elements from becoming entangled with each
other. The natural spring forces of the helical coil springs 136
provided in the apices of the vees serves to expand the graft to
its expanded position as soon as the graft is free of the capsule
36. By way of example, as shown in the drawings, three apices or
nodes can be provided in the plane 141 and three apices or nodes in
the plane 142 which are offset longitudinally with respect to the
nodes in plan 141 and six nodes in plan 143. The placement of six
nodes or apices 133 in the plan 143 does not interfere with the
compression of the graft 151 because there are no hook-like
elements 151 at these nodes or apices 133 in the plane. For larger
diameter grafts, the spring means 131 can be provided with
additional apices or nodes 133 to enhance attachment as hereinafter
described.
[0083] Radiopaque marker means is carried by the graft 121. The
radiopaque marker means takes the form of four radiopaque markers
156. The radiopaque markers are made of a suitable material such as
a platinum tungsten alloy wire of a suitable diameter such as 0.003
inches which is wound into a spring coil having a diameter of 0.040
inches and having a length of 0.125 inches. These markers 156 are
secured to the tubular member 122 by the same suture material 146.
Two of the radiopaque markers 156 are located on the tubular member
122 in spaced apart aligned positions longitudinally of and
parallel to the longitudinal axis of the tubular member 122 but are
adjacent to the apices 133 lying in the planes 143 at the opposite
ends 123 and 124 of the graft 121. Thus the markers 156 are spaced
a maximum distance apart on the graft but still within the
attachment means carried by the graft 121. Another set of two
markers is provided on the tubular member 122 spaced 180.degree.
from the first set of two markers along the same longitudinal axis
(see FIG. 15). By placing the markers in these positions, it is
possible to ascertain the position of the graft 121 and at the same
time to ascertain whether or not there has been any twist in the
graft between the first and second ends of the graft. In other
words when there is no twist in the graft 121 the four markers 156
form four corners of a rectangle. However, if a twist in the graft
121 is present, then the pair of markers 156 at one end of the
graft 121 have a different spacing transverse of the longitudinal
axis of the graft then the other pair of markers 156 at the other
end.
[0084] In order to ensure that the graft 121 will not become
dislodged after it has been implanted, it may be desirable to
provide alternative hook-like elements to ensure that the graft
will remain in place after it has been implanted. An alternative
hook-like element 161 is shown in FIG. 9 in which each of the
hook-like elements 161 has been provided with a barb 162 which
extends outwardly from the main body 163 of the hook-like element.
Thus by way of example, the main body 163 can be formed of a wire
having a suitable diameter such as 0.012 inches with the diameter
of the hook-like body in the vicinity of the barb 162 having a
suitable diameter such as 0.010 inches. The hook-like element can
have a suitable length such as 1.5 millimeters.
[0085] Another alternative hook-like element 166 is shown in FIG.
10 which has a body 167 of a suitable diameter such as 0.010 inches
with a conical tip 168. Outwardly extending spring-like ribbons 169
having a suitable dimension such as 0.002 inches in thickness and a
width of 0.008 inches are secured by suitable means such as welding
of the body 167. As shown, the spring-like elements 169 can flare
outwardly so that in the event any attempt is made to withdraw or
retract the hook-like element, the spring-like ribbons 169 will
become firmly imbedded in the tissue to inhibit such removal. It
also should be appreciated that other means can be provided on the
hook-like elements to inhibit withdrawal of the same from tissue
once they have become embedded in the same. Thus, by way of example
as shown in FIG. 13, helical or annular serrations 170 can be
provided on the hook body to inhibit such withdrawal. In each of
the embodiments with the hook-like elements it can be seen that the
profile of the hook-like element is kept to a minimum during the
time that it is penetrating the tissue.
[0086] The endovascular grafting apparatus 11 is shown assembled
for use as shown in FIG. 1 typically in the manner it would be
packaged for shipment to a hospital or doctor for use. As shown in
FIG. 1, the graft 121 has been compressed or squeezed onto the
balloon shaft 62 and is positioned within the capsule 36 with the
pusher button 66 being positioned immediately to the rear or
proximal to the proximal extremity 123 of the graft 121 (see FIG.
14). In this connection it should be appreciated in order to
minimize the diameter of the graft to make use of a capsule of
minimum diameter, the balloon catheter should be of minimum
profile. The balloon shaft 62 is threaded on the wire 98 and
extends into the rigid tube 97 of the pusher rod 96. The balloon 64
is disposed forwardly or distally of the capsule 36. The wire 98 is
in engagement with the plug 78 in the distal extremity of the
balloon 64.
[0087] When it is desired to perform a procedure utilizing an
endovascular or system grafting apparatus 11 of the present
invention to perform the method of the present invention, an
apparatus is selected which has the appropriate size of graft 121
within the capsule 36. The length and size of the graft 121 is
determined by the size of the vessel of the patient in which the
aneurysm has occurred. Typically the size of the graft 121 is
selected so that it has sufficient length to span approximately one
centimeter proximal and one centimeter distal of the aneurysm so
that the hook-like elements 151 of the graft can seat within normal
tissue of the vessel on both sides of the aneurysm. Thus, the graft
should be two centimeters longer than the aneurysm being repaired.
The diameter is selected by measuring the vessel in a preimplant
procedure by conventional radiographic techniques and then using a
graft 121 of the next larger one millimeter size. During the
preimplant fluoroscopy procedure, using a conventional pigtail
catheter, the locations of the renal arteries are ascertained so
that they will not be covered by the graft 121 when it is
implanted.
[0088] Let it be assumed that the patient on whom the operation is
to take place has been prepared in a conventional manner by use of
a dilator with a guide wire and a sheath (not shown) to open the
femoral artery or vessel of the patient. The apparatus 11 is
inserted into the sheath which has previously been placed in the
femoral artery of the patient. This insertion can be accomplished
without a guide wire, with a guide wire or by the use of a soft
sheath previously positioned over a guide wire. With the
construction shown in FIG. 3, the balloon 64 with its guide wire 74
followed by the capsule 36 is introduced into the femoral artery
and advanced in the femoral artery by the physician grasping the
proximal extremity of the capsule catheter 12 and the cap of the
pusher rod assembly 106. The balloon 64 is twisted into a helix to
place it in its helical memory condition to reduce its profile to a
minimum. The balloon 64 and the capsule 36 are advanced by the
physician into the desired position by use of the guide wire 74.
The physician slightly rotates the apparatus 11 in the direction of
the balloon twist to maintain the helical twist in the balloon 64
and pushes on the apparatus 11.
[0089] Typically a desired position will be within the abdominal
aorta with the proximal extremity 123 of the graft 121 and at least
one centimeter distal to the lower renal artery. At about the same
time, the physician should rotate the capsule catheter 12 to rotate
the capsule 36 and the graft therein in order to orient the
radiopaque graft markers 156 such that the distance between the
pair of markers 156 at each end of the graft 121 is maximized. As
soon the capsule 36 is in the desired position, the Touhy Borst
0-ring assembly 27 is opened to permit free movement of the pusher
rod assembly 96. With the balloon 64 riding well beyond or just
distal of the end of the capsule 36, one hand of the physician is
used for holding the pusher rod assembly between the pusher rod
assembly 96 by engaging the cap 101 and holding the pusher rod
stationary and pulling outwardly on the capsule catheter 12 with
the other hand to cause relative movement between the pusher rod
assembly 96 in the inner liner 17 and the capsule 36. This causes
the wire 98 of the pusher rod assembly 96 to engage the plug 78 of
the balloon catheter assembly 61. The pusher button 66 carried by
the balloon catheter shaft 62 which is in engagement with the
proximal extremity of the graft 121 in the region of the nodes 133
in the plane 143 forces the graft 121 out of the capsule 36 as the
capsule is withdrawn. As soon as the proximal extremity of the
graft has cleared the distal extremity of the capsule the proximal
extremity 123 of the graft 121 pops outwardly under the force of
the spring means 131 carried by the proximal extremity 123 of the
graft 121 and will spring into engagement with the vessel wall
166.
[0090] As soon as this has occurred, the pusher rod assembly 96 is
pulled out of the capsule catheter 12. While the physician uses one
hand to hold the capsule catheter 12 stationary, the catheter shaft
62 which is protruding proximally of the capsule catheter 12 is
grasped by the other hand and pulled rearwardly to position the
proximal extremity of the balloon 64 into the proximal extremity
123 of the graft 121 as shown in FIG. 15. A conventional hand
operated syringe and Touhy Borst adapter (not shown) are then taken
and attached to the proximal extremity of the balloon catheter
shaft 62. The balloon 64 is then expanded by introducing a suitable
gas such as carbon dioxide or a dilute radiopaque liquid from the
syringe to urge the hook-like elements 151 outwardly to firmly seat
within the vessel wall 166.
[0091] As soon as this has been accomplished, the capsule catheter
12 is pulled out further with the balloon 64 still inflated until
approximately one-half or more of the graft 121 has cleared the
capsule 36. Leaving the balloon inflated provides additional
security to ensure that the proximally seated graft 121 will not
move during retraction of the capsule 36. The balloon 64 is then
deflated. The balloon 64 is then retracted further into the graft
and reinflated to ensure that a good attachment is made between the
hook-like elements 151 carried by the spring means 131 at the
proximal extremity 123 of the graft 121. The capsule 36 can then be
removed in successive steps and the balloon deflated, retracted and
reinflated. The capsule catheter 12 can then be withdrawn
completely to the distal portion of the abdominal aorta to permit
the distal extremity 124 of the graft 121 to move out completely of
the capsule 36 and to permit its distal extremity 124 to spring
open and have the hook-like elements 151 move into engagement with
the vessel wall 166. Thereafter, the balloon 64 is again deflated.
The balloon catheter shaft is then grasped by the physician's hand
and pulled rearwardly to center the balloon 64 within the distal
extremity 124 of the graft 121. The balloon 64 is reinflated to set
the hook-like elements 151 at the distal extremity of the graft
into the vessel wall 166. As soon as this has been completed, the
balloon 64 is again deflated. The balloon catheter assembly 61 is
then removed from the femoral artery.
[0092] The entire procedure hereinbefore can be observed under
fluoroscopy. The relative positioning of the graft 121 and the
balloon 64 can be readily ascertained by the radiopaque attachment
means 131, radiopaque markers 156 provided on the graft, and the
radiopaque portions of the balloon 64. If any twisting of the graft
121 has occurred between placement of the proximal hook-like
elements and the distal hook-like elements, this can be readily
ascertained by observing the four markers 156. Adjustments can be
made before ejection of the distal extremity 124 by rotation of the
capsule catheter 12 to eliminate any twisting which has occurred.
In addition, the distance between the pairs of radiopaque markers
156 longitudinal of the axis is measured on the flat plate
abdominal x-ray made during the procedure and compared with the
known distance between the pairs of markers 156 longitudinal of the
axis of the graft 121 ascertained during manufacture of the graft
121. This is done to ascertain whether longitudinal according of
the graft 121 has occurred.
[0093] Post implant fluoroscopy procedures can be utilized to
confirm the proper implantation of the device by the use of a
conventional pigtail catheter. Thereafter the sheath can be removed
from the femoral artery and the femoral artery closed with
conventional suturing techniques. Tissues should begin to grow into
the graft within two to four weeks with tissue completely covering
the interior side of the graft within six months so that no portion
of the graft thereafter would be in communication with the blood
circulating in the vessel. This establishes a complete repair of
the aneurysm which had occurred.
[0094] It is apparent from the foregoing that there has been
provided a new and improved endovascular grafting apparatus, system
and method for utilizing the same. The construction of the capsule
catheter is such that it has sufficient rigidity to ensure easy and
ready placement of the capsule carried thereby. The pusher rod
assembly which is used therein is constrained in such a manner so
that relatively great forces can be applied to the pusher rod
assembly even though the pusher wire has only a diameter of 0.018
inches. The tube 69 also serves to provide a confined space for the
wire 98 to sit in while a high compressive force is being applied
to the wire. The tube 69 prevents the wire from buckling or kinking
within the balloon. It also prevents the balloon from collapsing
during insertion of the apparatus 11. The capsule 36 which is
provided as a part of the catheter assembly is formed of metal
which makes it possible to utilize grafts having very sharp
hook-like elements without any danger of then penetrating the
capsule during the time that the capsule is being introduced into
the vessel of the patient. In addition, the capsule since it is
flexible and can bend through angles up to approximately
120.degree. in order to readily negotiate the bends which occur in
the vessel of the patient. The balloon catheter is made in such a
way that the balloon can be readily introduced into the vessel
because of the rigid tubular member provided within the balloon
while at the same time permitting inflation and deflation of the
balloon through the same tubular member. The pusher button 66 is
mounted on the balloon catheter in such a manner so that it cannot
shift at all in one direction or proximally longitudinally of the
balloon catheter. The pusher button 66 also can only move a limited
distance towards the balloon 64 until it reaches the balloon 64. In
one embodiment shown in FIG. 3 the pusher button 66 cannot move
proximally or distally whereas in another embodiment shown in FIG.
4 it cannot move proximally but can move distally. This is an
advantage when retracting the proximal extremity of the balloon 64
into the graft 121 for placement of the proximal hook-like elements
151 because the pusher button 66 can slide forwardly or distally of
the shaft 62 as the shaft 62 is retracted to bring the proximal
extremity with the balloon 64 into the graft 121. Thus the pusher
button 66 will not be pulled back into the capsule 36 and catch on
the collapsed distal extremity 124 of the graft 121 within the
capsule 26. The balloon is also mounted on the distal extremity of
the balloon catheter in such a manner so that the balloon cannot
leak. The balloon catheter can be provided with either a fixed
guide wire, or if desired, a movable guide wire so that an
over-the-wire system can be utilized.
[0095] The capsule 36 is constructed in such a manner so that it is
semi-radiopaque allowing it to be visualized while still permitting
observation of the graft within the capsule and the attachment
means provided on the graft. The capsule 36 is also constructed in
such a manner so that the hooks which are provided on the graft
will readily slide in one direction over the wraps or turns of the
capsule without hanging up or catching onto the individual wraps of
the ribbon forming the capsule.
[0096] The graft which is provided with the helical coil springs at
each of the nodes is particularly advantageous in that it permits
compression of the graft into a very. small size without causing
permanent deformation of the attachment means. Because of the
spring forces provided by the attachment means, it is possible that
the grafts can be implanted without the use of an inflatable
balloon for forcing the hook-like elements into the tissue of the
vessel. However, at the present time, it is still believed to be
desirable to utilize the balloon to ensure that the hook-like
elements are firmly implanted into the wall of the vessel so as to
inhibit migration of the graft within the vessel.
[0097] As shown in FIG. 30 with reference to FIG. 29, the wire
attachment system 200 includes a wire frame 202 and is generally
sinusoidal in shape and surrounds the inside 204 of both ends of
the graft 206. The wire frame is a single continuous wire with a
first end 208 and a second end 210. The wire frame is formed into a
sinusoidal shape by bending the wire around a mandrel (not shown)
as known by one ordinary skilled in the art. The wire defines
alternating base apices 214 that are oriented inside the lumen of
the graft. The base apices point generally inward. Alternative
protruding apices 216 are formed to point, outward, in the opposite
direction of the base apices. The protruding apices generally past
the outer extremity of the graft when the wire frame is mounted
into the graft.
[0098] The terms of reference such as radial, longitudinal, and
lateral are defined in spacial relationship to the graft 206. For
example, longitudinally outward represents a direction parallel to
the axis of the graft outward from the middle of the graft to the
end. Terms defining spacial relationships of the attachment system
200 are oriented relative to the graft when the attachment system
is mounted into the graft. Thus a longitudinally outward protruding
apex 216 is an apex that protrudes longitudinally outward from the
graft.
[0099] Connecting each alternating apex 214 and 216 are struts 212.
The wire frame is made of a stainless spring steel or metal alloy
with a high amount of resilience or spring. An example of a
preferred wire found to be useful is "ELGILOY" brand
cobalt-chromium-nickel alloy manufactured and sold by Elgiloy of
Elgin, Ill. The struts are each connected to a protruding apex 216
and a base apex 214. Each apex is connected by a pair of struts
that define an angle between such pair of struts.
[0100] As illustrated in FIG. 30, the wire frame 202 is formed to
have circular continuity that does not destroy the generally
sinusoidal shape of the attachment system 200. The term continuity
as used herein, defines a wire frame that is affixed end to end so
that the frame is one continuous unit. The term circular refers to
the fact that the every other apex 214 and 216 is aligned in a
generally circular shape.
[0101] The sinusoidal shape is retained when there are an equal
number of base apices and protruding apices. The apex closest to
the first end 208 is a protruding apex and is referred to herein as
the first end apex 218. The apex closest to the second end 210 is a
base apex and is referred to herein as the second end apex 220.
Extending from the first apex to. the first end is a first partial
strut 222. The strut extending from the second apex to the second
end is the second partial strut 224. The first and second partial
struts are aligned but point in opposite directions. The length of
the first and second partial struts are predetermined to permit
overlap of the ends and are equal in length so that the portion of
the respective struts that overlap are equidistance fr om the first
and second end apices. The first and second partial struts are
welded at a point 226 equidistant from the first and second end
apices. Once welded together the first and second partial struts
act as a single strut.
[0102] The struts 212 and apices, 214 and 216, are biased to create
a radially outwardly directed force when the wire frame 202 is
affixed to the inner perimeter of the graft 204. This is
accomplished by compressing the struts together so that the angle
between the struts generally are smaller than attached when the
wire frame is permitted to relax to an equilibrium state. By
compressing the struts the longitudinal profile of the attachment
system decreases and the attachments system can be affixed to the
inside of the graft. When affixed to the graft, the attachment
system can relax and expand radially outward to bias the sides of
the graft against the wall of the vessel.
[0103] The attachment system 200 further includes a plurality of
lumen piercing members 228 affixed to the struts 212. The lumen
piercing members are designed to protrude radially outward from the
attachments system to engage the lumen wall of the blood vessel
(not shown in FIGS. 27 and 28) and secure the graft 206 in place.
The lumen piercing member includes a wire arm 232 constructed of
stainless steel wire having the same thickness as the wire in the
attachment system. The wire arm has a base end 234 that is welded
to the strut of the attachment system. The wire arm is formed with
a radially outward protruding hook 236 at the opposite end of the
base. The hook ends of the wire arm are positioned longitudinally
outward from the base end and extends outward past the adjacent
protruding apices 216. When affixed to an adjacent strut, the wire
arm is preferably aligned parallel to the strut. FIG. 30
illustrates that the lumen piercing members are affixed to every
other strut and have a point of weld generally proximal to the
outward end of the strut.
[0104] FIG. 16 likewise shows a lumen piercing member 228 attached
to a strut 212 adjoining a protruding apex 216 and a base apex 214.
However, the base end 234 of the arm 232 is affixed to the strut at
a point 238 equidistance from the adjacent protruding apex and base
apex. The weld 226 is centered between the top end 240 and bottom
end 242 of the strut. The arm of the lumen piercing member is
tangential to the strut at the point of the weld. FIG. 16.
illustrates how metal fatigue of the welded lumen piercing member
can be minimized by locating the weld equidistant from the top and
bottom of the strut.
[0105] While the example of FIG. 16 concerns a lumen piercing
member 228 welded to a strut 212, the principles described herein
apply to any weld in the attachment system including a weld
connecting two partial end struts. FIG. 17 illustrates measurement
of the compression and tension of the strut at various points along
the side of the strut 248 that is welded to the lumen piercing
member 228 during a cardiac cycle. Tension is observed when a wire
that has resilience and spring is bent from an equilibrium state in
an arch.
[0106] Compression is observed in the triangular regions
represented by numeral 244 at the top and bottom of the strut.
Compression is caused when the molecular lattice of the wire is
compressed together such that the wire molecules are closer
together than if they were in no state of equilibrium. The force
arrow 233 indicates the internal repulsion force that biases the
wire towards its equilibrium state.
[0107] Tension is observed in the triangular regions indicated by
reference numeral 246 on the top half and the bottom half of the
strut. The tension results when the molecular lattice of the wire
is pulled apart from its state of equilibrium. A force internal to
the wire in the direction of force arrows 235 and 237 can be
observed that biases the wire back to its original position.
[0108] FIG. 17 is a graphic representation of the tension or
compression of the strut 212 in FIG. 16 during a cardiac cycle. The
first curve 250 represents the tension and compression at a point
at the top of the strut 240. The second curve 252 represents the
tension and compression at the top of the weld 258. The third curve
254 represents the tension and compression at a point at the bottom
of the weld 260. The fourth curve 256 represents the tension and
compression at the bottom of the strut 242.
[0109] With continued reference to FIG. 16 and FIG. 17, the wire
frame 202 is in a partially compressed position during the entire
cardiac cycle. At least some compression of the wire frame when
mounted into a blood vessel lumen is preferred in order to maintain
a radial outward force sufficient to hold the graft against the
inner wall of the lumen. Since the wire frame is preferably
partially compressed at all times throughout the cardiac cycle, a
measurable amount of compression and tension will exist at various
points along the strut 212. The tension is greatest at the top 240
of a partially compressed strut than any other point along the side
248 of the strut that is welded to the lumen piercing member. At
the top of the weld 258, some tension exist, but is considerably
less than at the top of the strut. At the bottom of the weld 260,
conversely, compression rather than tension exists and has a
magnitude approximately equal to the magnitude of tension at the
top of the weld. Furthermore at the bottom of the strut 242, the
amount of compression of the metal is maximum at the bottom of the
strut in an amount proportional to the bottom of the weld.
[0110] As the cardiac cycle begins, the blood vessel lumen
contracts causing each strut 212 to bend slightly increasing the
tension slightly along the top half of the strut and increasing the
compression along the bottom half of the strut. Once the
compression of the blood vessel reaches a maximum 262, the blood
vessel relaxes causing the tension at the top of the strut 240 and
the top of the weld 258 to decrease to a minimum. Likewise, the
bottom of the strut 242 and the bottom of the weld 260 respond to
the relaxation of the blood vessel with a decrease in the amount of
compression to a minimum 264. The cardiac cycle becomes complete as
the blood vessel again begins to constrict again causing an
increase in the tension at the top of the strut and the top of the
weld respectively, as well as a decrease in the compression at the
bottom of the vessel. Throughout the cardiac cycle, the midpoint
238 defined as the point along the strut that is exactly
equidistant between the protruding apex 216 at the top of the strut
and the base apex 214 at the bottom of the strut. The compression
of the upper portion of the graft and tension of the lower portion
of the graft are equal in magnitude at any two given points that
are equal distance from the midpoint throughout the entire cardiac
cycle. Consequently, the magnitude of compression or tension
remains constant absent any compression or tension throughout the
cardiac cycle.
[0111] Observation of the compression and tension at various points
along a strut 212 during the cardiac cycle reveals two important
facts. First, the magnitude of compression or tension decreases
along the strut toward the midpoint 238. Second, the differential
between the magnitude of the maximum and minimum tension or
compression during the cardiac cycle decreases along the length of
the strut from the respective ends 240 and 242 to the midpoint.
From a practical standpoint, the tension and compression
contributes to metal fatigue of a wire spring and particularity to
a weld 226. Consequently, metal fatigue of the weld is minimized
when the weld is located as close to the midpoint of the strut as
possible.
[0112] Another way of reducing the affect of metal fatigue is to
create a wire frame 202 that has no welded parts. FIGS. 18 through
23 illustrate an attachment system for a graft 206 that with a
lumen diameter of twenty-six millimeters which is a typical size of
an aorta. The dimension given below relate to an attachment system
200 for a graft with a lumen diameter of twenty-six (26)
millimeters. It shall be apparent to one skilled in the art that
the dimensions may be adjusted to fit lumens of different sizes
without departing from the spirit of the invention.
[0113] To create an attachment system 200 without welds, the welded
lumen piercing members 228 illustrated in FIGS. 30 and 16, must be
replaced with a lumen piercing member that can be included in the
attachment system in such a manner that the lumen piercing members
will be responsive to the compression of the spring without welding
the lumen piercing members to the wire frame 202. Furthermore, the
attachment system must be mounted to the graft 206 so that the wire
frame effectively exerts a constant force around the entire
periphery of the graft. One embodiment of such an attachment system
can be observed in FIGS. 18 through 23.
[0114] As shown in FIG. 18 with continued reference to FIG. 19, the
attachment system 200 is configured to affix an end of a tubular
graft 206 that may have two or three ends. The graft is generally
tubular in shape and is designed to fit into a blood vessel such as
the aortic, thoracic, or iliac arteries for repair of an aneurism.
The general shape of the wire frame is sinusoidal. The sinusoidal
frame has longitudinally inwardly directed base apices that are
affixed to the graft longitudinally inward from the outer
extremity. Alternatively spaced between the sinusoidal frame are
outwardly directed protruding apices A1 through A9 that extend
outward from the end of the graft. As shown in the embodiment
illustrated in FIG. 19, the wire frame has a first end 208 and a
second end 210. The first and second ends of the wire frame are
wound into helical coils or helices with one and a half rotations.
The helixes on the first and second ends have an inside diameter of
0.031 inches (0.79 mm) and are respectively referred to as first
end helix 266 and second end helix 268.
[0115] The sinusoidal wire frame 202 is formed with nine outward
protruding apices numbered A1 through A9 respectively beginning at
the protruding apex A1 closest to the first end helix 266. Each of
the apices are wound into a helical spring coil 270. Apex A1 and A9
are respectively the two apices that are closest to the first and
second end helices. The alternating base apices are numbered for
reference B1 through B9 beginning with the base apices closest to
apex A1.
[0116] Each of the protruding apices A1 through A9 are integrally
connected to adjacent base apices B1 through B8 by struts 212. As
observed in FIG. 1A, not all of the struts are of equal length.
Rather, the length of the struts are configured to stagger the
apices along different planes that are spaced longitudinally apart
and are perpendicular to the axis of the tubular graft 206
according to the pattern described below. It is an important
objective of the present invention to create a narrow profile for
the attachment system 200 when the attachment system is constricted
radially. Since the helical apices tend to have a greater radial
width than the struts, staggering the apices serves the purpose of
creating a narrow profile for insertion into a capsule.
[0117] The helixes 270 located at outward protruding apices A1
through A8 are aligned slightly outward from the end of the graft
206. This accomplishes the purpose of minimizing the radial profile
of the graft in collapsed position. The graft provides considerable
bulk to the attachment system 200 and positioning the apices A1
through A8 beyond the end of the graft distributes longitudinally
the bulk of the graft and helices. To further minimize the bulk of
radial profile of the attachment system, the struts 212 that are
adjacent to apex A9 are shortened slightly to offset apex A9
longitudinally inward from the end of the graft. Consequently, apex
A9 when assembled and sewn into the graft is offset longitudinally
inward from apex A1 and does not overly the same.
[0118] The helixes 270 located at the base apices B1 through B8 as
well as the two end helices 266 and 268 respectively are staggered
considerably. Apices B1, B3, B5, and B7 are configured with
slightly larger diameter helices 276 to accommodate the lumen
piercing members 274 which are bent into the shape of a vee.
V-shaped lumen piercing members 274 will fit between the struts 278
adjacent to apices B1, B3, B5 and B7 in a close proximal
relationship. The lengthened struts that connect the apices are
sufficiently long to orient the apices B1, B3, B5 and B7 0.70
inches (17.8 mm) longitudinally inward from the protruding apices.
Furthermore, the diameter of the enlarged helices 276 at apices B1,
B3, B5, B7 are 0.63 inches (1.2 mm), which is considerably larger
than the diameter of remaining smaller helices 282 formed in the
wire frame 202. The smaller helices 282 have a diameter of 0.42
inches (1.1 mm). The enlarged helices 276, in combination with the
lengthened struts 278, create a space between the struts 278 that
extend longitudinally outward from the enlarged helices 276 formed
in apices B2, B4, B6 and B8 that conform in shape to the V-shaped
lumen piercing members 274 such that the lumen piercing members can
fit into the attachment system in close proximity to the lengthened
struts and the enlarged helices, without contacting or rubbing
against the same.
[0119] Apices B2 and B6 may be further staggered with respect to
apices B4 and B8. Apices B2 and B6 are oriented 0.46 inches
longitudinally inward from the protruding apices. Apices B4 and B8
are oriented 0.36 inches longitudinally inward from the protruding
apices. The first end helix 266 is also aligned 0.36 inches from
the protruding apices.
[0120] As shown in FIG. 21, it may not be necessary or desirable
under some circumstances to stagger apices B2 and B6 relative to B4
and B8. For example, the profile of the protruding apices A1
through A8 and the hooks 236 of the attachment system 200 might be
sufficiently large that even if the staggering of helices B2 and B6
relative to B4 and B8 occurred it would not serve to reduce the
diameter of the overall capsule. When staggering apices B2 and B6
relative to B4 and B8 would not serve to facilitate the use of a
narrower capsule or delivery system, then aligning such apices
along a fourth plane 288 that may be oriented between 0.36 inches
to 0.46 inches longitudinally inward from the first plane 272.
[0121] The wire frame 202 of the attachment system 200 illustrated
in FIGS. 18 through 21 is designed to fit inside a graft 206 that
has a diameter of twenty-six (26) millimeters. When affixing the
frame to the tubular graft, the wire frame is preferably partially
compressed to maintain a constant outward bias against the wall of
the graft. The two ends of the wire frame, 208 and 210, overlap so
that the first end helix 266 is aligned longitudinally outward from
apex B8. Apex A1 is longitudinally aligned with apex A9. The second
end helix 268 is aligned with apex B longitudinally inward from
apex B.
[0122] The attachment system 200 including the wire frame 202 and
the V-shaped lumen piercing members 274 are sutured to the graft
206 at various points throughout the graft. The sewing pattern can
best be viewed with reference to FIGS. 19 or 21 showing the
stitching from the perspective of the inside of the graft.
[0123] In the embodiment illustrated in of FIGS. 18-19, the
V-shaped lumen piercing members 274 are not welded to the wire
frame 202, but rather are sewn into the graft 206 in close
proximity to the sinusoidal wire frame and are responsive to the
compression and expansion of the wire frame. To provide stability
and flexibility, the lumen piercing members are formed from a
single strand of wire with two ends 290 and 292. The wire is bent
into a V-shape having an apex 294 and two outwardly protruding arms
296 and 298 that form an acute angle when in relaxed position. The
two ends of the wire are bent radially outward to form hooks that,
when mounted to the graft, are designed to pierce into the wall of
the blood vessel. As shown in FIGS. 19-21, the hooks are shown to
point tangential to the graft perimeter. These illustrations are
merely to show what the hooks look like. In actuality, the hooks
would be directed at an angle perpendicular to the paper at such an
angle, the hooks would be difficult to illustrate.
[0124] Each hook forms an angle with its respective arm ranging
from ninety degrees to forty five degrees, but preferably seventy
(70) degrees as shown in FIG. 31 with angle Sigma (.sigma.) 303.
The wire of each V-shaped lumen piercing member is wound at the
apex to form a helical coil 300. Such a helical coil contributes to
the outward bias and spring of the entire attachment system. Absent
such a design feature, the V-shaped lumen piercing members would
not be as responsive to the contractions of the graft. Moreover,
the fatigue life of the hooks are extended because the helical
design distributes the tension of the wire over the helix when the
arms of the lumen piercing member are subject to continual
contractions caused by the pulsing of the blood vessel during the
cardiac cycle. The diameter of the apices in the embodiment
illustrated in FIG. 19 should have an outside diameter ranging
between 0.025 inches and 0.060 inches and preferably 0.047
inches.
[0125] There are four pairs of V-shaped lumen piercing members 274
in the embodiment illustrated in FIGS. 19 and 20. The number of
V-shaped lumen piercing members mounted depends upon the number of
pairs of protruding apices 214 and base 216 apices, discounting the
number of apices that overlap at the ends of the wire frame (i.e.,
apex A1 overlaps with apex A9). The V-shaped lumen piercing members
are placed around the graft equally spaced apart fitted into the
space between the elongated struts 278 are adjacent to apices B1,
B3, B5, and B7. The arms of the V-shaped lumen piercing members
extend parallel to adjacent elongated struts. The V-shaped lumen
piercing members of the embodiment illustrated in FIG. 19 has a
length of 15-17 mm and a helical diameter of 0.047 inches.
[0126] The hooks 292 have a length of two to three millimeters and
are sharpened at the tips 302. The hooks may be sharpened with a
conical tip 305 as shown in FIGS. 19 through 21 or with a duck
billed tip 307 as shown in FIG. 32. A conical tip is formed when
the wire tip is held at an angle against the sharpening tool (not
shown) and rotated. The duck bill tip is formed by holding one side
of the tip of the hook 292 against the sharpening surface (not
shown) at an angle. Not rotating the wire results in an oblong flat
surface 302 and a sharpened curved cutting edge 304 that cuts into
the blood vessel wall when the hook is pressed against the vessel
wall.
[0127] One possible method of attaching the V-shaped lumen piercing
members 274 to the frame can be observed with reference to FIGS. 19
and 20. As can readily be observed, the helices of the V-shaped
lumen piercing members are located on the outside of the graft 306
while the arms 296 and 298 extend parallel to the struts along the
inside of the graft 306. By mounting the V-shaped lumen piercing
members directly through the fabric of the graft, the V-shaped
lumen piercing members will be mounted more firmly. Furthermore,
the fabric of the graft separates the helix of the V-shaped lumen
piercing member 300 from the respective adjacent enlarged helices
276 and thereby prevents the helices of the V-shaped lumen piercing
member from rubbing against the adjacent base helices.
[0128] The V-shaped lumen piercing members 274 are mounted into the
graft by pressing together the two arms 296 and 298 of the V-shaped
lumen piercing members until the hooks are separated by a distance
approximately equal to the outer diameter of the helices. The hooks
are then punctured through the fibers of the graft from the outside
of the graft wall 306 to the inside of the graft 308. The entry
holes made by the V-shaped lumen piercing members are spaced
longitudinally outward by more than the outer diameter of the
helices 300 of the V-shaped lumen piercing members. The spacing
apart of helices 300 of the V-shaped lumen piercing members
prevents them from radially overlapping the enlarged base helices
276. This longitudinal spacing also furthers the goal of
distributing the bulk of the attachment system 300 thereby
narrowing the radial profile of the graft 306 when in a compressed
state. The apices of the lumen piercing member, prior to insertion
of the hooks through the graft, point outward towards the end of
the graft. The two hooks should preferably be laterally aligned so
that the entry holes 310 through the graft wall created by the
hooks are laterally aligned. The V-shaped lumen piercing members
are pressed through the puncture holes and slid inward along the
arms until the helix 300 contacts the outer wall of the graft. The
V-shaped lumen piercing members are inverted to an upright position
thereby orienting the hooks radially outward to engage the wall of
the blood vessel.
[0129] The arms 298 of the V-shaped lumen piercing members 274 are
compressed before being sewn to the graft 206 to maintain the
outward bias of the graft. The distance between the arms at the
edge of the graft is preferably six to seven millimeters. The arms
are sutured to the graft parallel to and in close proximal
relationship to the struts 278 adjacent to the V-shaped lumen
piercing members. The arms of the V-shaped lumen piercing members
are generally not sutured directly to the adjacent struts. The arms
of the V-shaped lumen piercing members and the adjacent struts are
sutured separately in order to prevent them from rubbing
together.
[0130] The attachment system 200 is inserted into a capsule (not
shown). When the graft 206 is deployed to the appropriate location
by a catheter delivery system (not shown), the graft is removed
from the capsule. Immediately upon removal, the attachment system
exerts a radially outward force on the wall of the graft biasing
the graft against the wall of the vessel 198. The deployment
balloon (now shown) is then used to further force the wall of the
graft against the wall of the vessel and to cause the hooks 236 of
the attachment system to pierce the vessel wall.
[0131] FIG. 22 is the cross section of a blood vessel that has a
graft 206 implanted into the wall of the vessel 198. The hooks 236
are implanted into the wall but preferably do not puncture through
the wall of the blood vessel. The protruding apices 216 can be
observed around the top of the graft 196. The pressed portion of
the graft 312 that is directly pressed against the vessel wall by
the wire frame 202 forms a seal that assists in the prevention of
fluid leaking around the end of the graft. Since the wire frame is
continuous, the portion of the graft that is pressed directly
against the vessel wall should in most cases be continuous. The
relieved portions of the graft 314 are the parts of the graft that
are not directly pressed against the wall of the vessel. The
relieved portion of the graft are most vulnerable to leaks.
[0132] Leaking is also more likely to occur if the vessel is
deformed. For example, the graft may have a slightly larger
diameter than the inner dimension of the vessel or the vessel wall
may not be smooth. In such circumstances, pleats in the graft are
sometimes formed between the struts 212. Another factor that
increases the likelihood of pleating is the pulsing of the blood
vessel during the cardiac cycle as described above. When the blood
vessel is contracted, pleating may be mildly accentuated.
[0133] The further prevention of leaks can be accomplished by
texturing the outside of the graft 306 with a plurality of
filaments or fibers that are spun, woven, knotted, pressed or
otherwise loosely associated to form a puffed textured filler that
can be sewn to or affixed to the outside of the graft proximal to
the end of the graft. The filler of the embodiment illustrated in
FIG. 18 with reference to FIG. 20 includes stitches of a
biocompatible synthetic yarn called tufts 318. The tufts are formed
by stitching two or more strands 320 of synthetic yarn into the
graft with the ends of the strands pointing outward from the side
of the graft. The strands can be formed or knotted by employing a
double knot or a square knot. The ends of the strands can be frayed
to increase the surface area exposed and to distributed the
filaments as much as possible.
[0134] A possible pattern of orienting the fibrous tufts 318
includes covering the graft 206 proximal to the perimeter of the
attachment system with batting or by sewing loosely spun synthetic
yarn such as polyester around the perimeter of the graft. Such a
configuration would certainly fill all of the gaps that may arise.
However, when considering the competing need of maintaining a
narrow profile for the attachment system and graft in order to fit
the attachment system into a capsule, the more spatially
conservative approach may be preferred.
[0135] FIG. 20 illustrates an example of a pattern of placing
fibrous tufts in a more spatially conservative pattern. The tufts
318 while conserving radial bulk of the graft, cooperate with the
attachment system to minimize leakage of blood. As previously
stated, the parts of the graft that are most vulnerable to leaks
are the relieved portion of the graft 314. Therefore, the tufts
will be centered in between such places. For example, a first row
322 of tufts are sewn into the spaces between the protruding apices
three to five millimeters longitudinally inward from the end of the
graft. The tufts are trimmed to three to five millimeters in
length. The ends of the tufts are teased or frayed to spread out
the filaments throughout the relieved portion of the graft.
[0136] A second and third row of tufts 326 are respectively sewn to
the graft 206 near the base apices. The second row of tufts 324 are
two to five millimeters longitudinally outward from the base apices
B2, B4, B6, and B8. The second row has eight tufts and each tuft is
radially aligned with each protruding apex 1-8. The second row of
tufts are located three to seven millimeters longitudinally inward
from the first row and are radially aligned with each of the eight
base apices B1-B8. Each of the tufts in the second and third rows
are five to seven millimeter long.
[0137] Polyester tufts are knotted directly onto each helix of the
V-shaped lumen piercing members which are located on the outside of
the graft 308. The polyester tufts are designed to seal the holes
in the graft created by puncturing the hooks 236 of the V-shaped
lumen piercing member through the wall of the graft as well as
provide a surface covering the apex that can bind to tissue growth
of the graft.
[0138] Referring now to FIG. 22 with continued reference to FIG.
23, the tufts can be observed around the outer surface of the graft
306 between the protruding apices 216. These tufts serve two
purposes. First, when a leak occurs, the fiber of the tufts assist
in the clotting of the leak. By way of illustration, a pleat 316 is
shown between two apices. A tuft 318 is sutured to the graft within
the pleat. A space 328 is created between the pleated graft that is
vulnerable to leaks. The filaments or strands 320 of the tufts
provide a surface to which blood 330 may clot to fill the space and
prevent further leaks. A second benefit becomes apparent once the
graft has been in place for a considerable period of time and the
tissue 332 begins to build up along the wall of blood vessel 198.
The tissue growth 332 that builds up to the side of the graft from
the blood vessel wall further anchors the ends of the graft 206 to
the wall.
[0139] Another embodiment of the present invention includes an
attachment system that is well adapted to affix a graft into the
iliac arteries as illustrated in FIGS. 24 through 28. The wire
frame has two wire frame parts 334 and 336 that are bent into a
generally sinusoidal shape and are respectively referred to as the
first and second wire frames. The first wire frame 334 terminates
in a first end 338 and a second end 340. Each frame has four base
apices. The base apices of the first frame are numbered D1, D2, D3,
and D4 beginning with the apex closest to the first end. The second
wire frame also has four base apices numbered D5, D6, D7 and D8 in
order beginning with the apex closest to first end 342 of the
second frame. Each wire frame has three protruding apices. The
first frame has protruding apices labeled from said first end to
said second end respectively, C1, C2, C3. The second wire frame has
protruding apices labeled from said first end respectively, C4, C5,
and C6. All of the apices have helical coils 346 with a 0.031 inch
diameter. The wire has a 0.010 inches (0.25 mm) diameter for ten to
fourteen millimeter grafts and is made of an alloy as described
above.
[0140] Lumen piercing members 348 extend outward from apices D1 and
D4 towards said first end 338 and second end 340 of said first wire
frame 334 respectively. Similarly, lumen piercing members extend
outward from apices D5 and D8 towards said first end 342 and second
end of said second wire frame 336 respectively. Each lumen piercing
member has a longitudinally outward protruding arm 350 that is
approximately one millimeter in length. At the outermost extremity
of the lumen piercing member, the arms are bent in a radially
outward direction to form hooks which are designed to pierce the
lumen to which the graft is being affixed. While the hooks in FIG.
26 are shown to protrude at a tangent to the circumference of the
graft, this representation merely shows the angle of the hooks.
[0141] The base apices are preferably sewn to the outer extremity
of the graft and are spaced equally around the circumference at six
points with two pairs of overlapping base apices. Base apex C1
overlaps with base apex D8 when affixed to the graft. Base apex D5
likewise overlaps apex D4.
[0142] An important feature of the present invention is how the two
wire frames 334 and 336 can be affixed together to cooperate as a
single wire frame unit without actually welding the two frames
together. The first and second wire frames are affixed together by
wrapping the arm 350 of the lumen piercing member around the
adjacent strut 352 through 356 when oriented with the overlapping
base apices above. For example, the lumen piercing member on the
first end 338 of the first wire frame is wrapped around the strut
352 extending between base apex D8 and protruding apex C6. The
lumen piercing member on the second end of the second wire frame is
wrapped around the strut 354 extending between base apex D1 and
protruding apex C1. The lumen piercing member on the second end 340
of the first wire frame is wrapped around the strut 356 extending
between base apex D5 and protruding apex C4. The lumen piercing
member on the first end of the second wire frame is wrapped around
the strut 358 extending between base apex D4 and protruding apex
C3.
[0143] By wrapping around, it is meant that the arm 350 of the
lumen piercing member 348 makes at least one full twist around the
adjacent strut 356. It is desirable that the struts rest against
the inside edge of the adjacent protruding apices C1-C6. When the
arm, after being twisted around the adjacent strut is radially
inward from the protruding apex, the spring tension caused by
twisting the wire arms together with adjacent struts 350-356 more
forcefully biases the arm outward. In some instances, the arm can
be further supported by the protruding apex by threading the arm
through the eye of the helix of the protruding apex.
[0144] As shown in FIGS. 24 and 26, the pair of wire frames 334 and
336 are sewn preferably to the outward extremity of the graft 358.
When necessary to conserve length of the graft assembly 206, the
wire frame pair may be inset inside the tubular graft two to five
millimeters from the outward extremity of the graft. The base
apices D1 through D8 are spaced equally around the graft. The base
helices are slightly compressed when sewn into the graft. When the
attachment system is relaxed, the protruding apices extend radially
outward past the circumference of the graft in a generally
frusto-conical configuration as shown in FIG. 24. This
configuration is primarily due to the base apices D1 through D8
being restricted from fully expanding to equilibrium. The
protruding apices C1 through C6 are not sewn into the graft and
expand radially outward farther than the base apices. The
circumference of the protruding apices of the attachment system can
be adjusted by compressing the protruding apices radially inward.
Such adjustment can be accomplished without causing the base apices
to respond in an inward direction. This feature improves the fit of
the graft in blood vessels that are diseased or similarly do not
have smooth lumens with consistent diameters.
[0145] FIGS. 27 and 28 illustrate the attachment system of FIG. 25
positioned within two diseased blood vessels 360 and 362. The blood
vessel in FIG. 28 has a mild bulge 364 providing an increased
inside diameter vessel lumen. The normal vessel lumen has an inner
diameter comparable in size to the outer diameter of the graft 20
at the end of the graft. The base apices cooperate with the struts
to exert an outward bias of the attachment system against the walls
of the vessel, securing the end of the graft within the lumen. The
diameter of the vessel adjacent to the protruding apices is
considerably larger than the diameter of the graft. Since the
protruding apices are capable of extending radially outward past
the diameter of the graft, the protruding apices are capable of
biasing the hooks 348 against the larger diameter lumen.
[0146] FIG. 27 shows a vessel where the diameter of the vessel
tapers radially inward from the end of the graft to form a
constricted area 366. The attachment system 333 remains able to
conform to the abnormal shape of the vessel. The protruding apices
346 are capable of being constricted radially inward without
eliminating the outward bias exerted by the base helices against
the outer periphery of the graft. The ability of the attachment
system to adjust to the various shapes of diseased vessels stems
from an important design feature that allows each helix to act as
point of rotation for the adjacent strut pairs. Consequently, each
helix is capable of facilitating the formation of an angle between
the adjacent struts with little or no interference caused by the
angle of the other struts. This feature in combination with the
sinusoidal shape allows the wire frame to adapt to a number of
abnormally shaped or diseased vessels.
[0147] Referring again to FIG. 26, the embodiment illustrated
therein includes a cross stitched strand of loosely spun synthetic
yarn 368. By loosely spun, it is meant that the individual strands
of yarn have a puffy texture with a large amount of surface area
exposed. The cross stitched pattern is offset approximately 2 to 5
millimeters longitudinally inward from the end of the graft 206. If
the base apices are sewn to the graft inward from the end of the
graft as illustrated in FIG. 25, the location of the synthetic yarn
will be longitudinally displaced one to five millimeters inward
from the row of base apices sewn to the graft. The stitching in
this embodiment occurs in a cross hatch or herringbone pattern. The
entire circumference of the graft is covered by the synthetic yarn.
Because the stitching is located longitudinally inward from the
helices, a narrow profile of the compressed graft can be
maintained. If, however, the narrow profile of the attachment
system can be maintained, the synthetic yarn can be sewn around the
perimeter of the graft radially outward from the wire frame.
[0148] As viewed in FIG. 29, the graft 206 of the present invention
has a plurality of radial crimps 371 spaced longitudinally along at
least a portion of the length of the graft. The crimps form a
generally corrugated tubular surface defining a plurality of
radially outwardly protruding ribs 372 that are separated
longitudinally by alternating inwardly directed folds or pleats
374. The distance between each crimp is generally two to three
millimeters apart. The radial depth of the ribs is one to two
millimeters.
[0149] The crimps 371 can be formed by methods known to one skilled
in the art such as heat crimping. A crimp iron (not shown) with a
heating desired element that is formed into the general shape of
the crimping pattern may be placed into the lumen of the graft 206.
The graft is tied radially inward at each pleat 374. Finally, the
crimp iron is heated causing permanent crimps in the graft. It must
be noted that the length of the graft should be adjusted to offset
the longitudinal shrinkage caused by heat crimping the graft. For
example, a seventy millimeter crimped graft with crimps along
twenty millimeters of the graft must use an uncrimped graft that
will have a pre-crimped length of about eighty millimeters.
[0150] The crimped configuration in the graft 206 has benefits. The
crimps 371 prevent kinking in the graft when the graft is deployed
in the lumen of angulated vessels. Uncrimped vessels have a greater
tendency to form kinks at the angulations, creating an uneven
surface within the vessel. Such kinks will cause more turbulence in
the vessel.
[0151] Another benefit resulting from adding crimps 371 to the
graft 206 is due to the patient's respiratory cycle. Certain blood
vessels undergo a length change due to the respiratory cycle. The
length change of blood vessels may cause considerable stress on the
attachment system implanted into the wall of the blood vessel.
Crimping of the graft allows a certain longitudinal flexibility of
the graft and blood vessel to reduce the stress exerted upon the
attachment system.
[0152] One of the considerations when determining whether or not to
crimp the graft is the goal of spatially distributing the bulk of
the graft and the attachment system longitudinally. Because the
crimping substantially increases the radial profile of the graft
when in a collapsed position, the amount of crimping must be
carefully considered. For example, the graft is not crimped along
the portion of the graft that surrounds the attachment system.
Also, crimps are placed along the graft at locations which are
likely to be placed adjacent an angulation of the vessel.
[0153] It will be apparent from the foregoing that, while
particular forms of the invention have been illustrated and
described, various modifications can be made without departing from
the spirit and scope of the invention. Accordingly, it is not
intended that the invention be limited, except as by the appended
claims.
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