U.S. patent number RE40,404 [Application Number 09/464,610] was granted by the patent office on 2008-06-24 for thinly woven flexible graft.
This patent grant is currently assigned to Maquet Cardiovascular, LLP. Invention is credited to Jose F. Nunez, Peter J. Schmitt.
United States Patent |
RE40,404 |
Schmitt , et al. |
June 24, 2008 |
Thinly woven flexible graft
Abstract
A thinly woven textile prosthetic implant such as a vascular
graft may be implanted by catheter implantation. The implant
includes an elongate tubular body formed of a woven fabric having a
fabric thickness no greater than about 0.16 mm. The tubular body
includes a series of longitudinally spaced wave-like generally
uniform crimps along the length thereof. The crimps are disposed at
a fine pitch along the length of the tubular body. The amplitude of
the crimps is relatively small thus reducing the formation of
thrombus and plaque on the inside of the implant.
Inventors: |
Schmitt; Peter J. (Garnerville,
NY), Nunez; Jose F. (St. Anthony, MN) |
Assignee: |
Maquet Cardiovascular, LLP (San
Jose, CA)
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Family
ID: |
23093780 |
Appl.
No.: |
09/464,610 |
Filed: |
December 15, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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08285334 |
Aug 2, 1994 |
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Reissue of: |
08650783 |
May 20, 1996 |
05697970 |
Dec 16, 1997 |
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Current U.S.
Class: |
623/1.51 |
Current CPC
Class: |
A61F
2/06 (20130101); A61F 2/07 (20130101); A61F
2002/065 (20130101); A61F 2250/0098 (20130101) |
Current International
Class: |
A61F
2/06 (20060101) |
Field of
Search: |
;623/1.49,1.5,1.51,1.52,1.54 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2913510 |
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Oct 1979 |
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DE |
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0 095 940 |
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Dec 1983 |
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EP |
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2 115 776 |
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Sep 1983 |
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GB |
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WO 83/03347 |
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Oct 1983 |
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WO |
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WO 88/06026 |
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Aug 1988 |
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WO |
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WO 89/00031 |
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Jan 1989 |
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WO |
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Other References
Belin, R.P., et al., A Method to Prevent Torsion of Arterial
Prosthetic Grafts, Journal of Thoracic and Cardiovascular Surgery,
vol. 54, No. 1, p. 497/1967. cited by other.
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Primary Examiner: Gherbi; Suzette
Attorney, Agent or Firm: Hoffmann & Baron, LLP
Parent Case Text
This is a continuation of application(s) Ser. No. 08/285,334 filed
on Aug. 2, 1994, abandoned May 21, 1996.
Claims
What is claimed is:
1. A woven textile prosthetic implant comprising: an elongate
tubular body formed of a fabric wall having a fabric wall thickness
no greater than about 0.16 mm, said tubular body having
longitudinally spaced wave-like, generally uniform
.Iadd.circumferential .Iaddend.crimps along the length thereof,
said crimps extending on both sides of said tubular body and having
a crimp frequency of no less than about 6 crimps per
centimeter.
2. A woven textile prosthetic implant of claim 1 wherein said
tubular body includes an x-ray detectable, radiopaque yarn
therein.
3. A woven textile prosthetic implant of claim 2 wherein said
radiopaque yarn extends longitudinally along the length of the
tubular body.
4. A woven textile prosthetic implant of claim 1 wherein said
wave-like crimps have a peak-to-peak amplitude of no greater than
about 0.5 mm.
5. A woven textile prosthetic implant of claim 1 wherein said body
has a fabric thickness of about 0.12 mm and a maximum crimp
frequency of about 42 crimps per cm.
6. A woven textile graft comprising: an elongate tubular graft body
having a wall, said wall having a thickness of no greater than
about 0.16 mm and defining a pattern of wave-like crimps extending
along both sides of said tubular body, the number of crimps, C, per
centimeter of body length being defined by an equation:
C=[2(t/10)].sup.-1; wherein t equals the body wall thickness in
mm.
7. A woven textile graft of claim 6 wherein said wave-like crimps
define a peak-to-peak amplitude of no greater than about 0.5
mm.
8. A woven textile graft of claim 7 wherein said tubular body
includes a radiopaque marker therein.
9. A woven textile graft of claim 8 wherein said marker extends the
length of said tubular body.
10. A woven textile graft of claim 1 wherein said tubular body is
bifurcated.
11. A woven textile intraluminally implantable graft comprising: an
elongate tubular graft body having a wall, said wall having a
thickness of dimension such that the graft body is capable of being
radially compressed for insertion into a delivery catheter; said
tubular graft body having a plurality of longitudinally spaced
wave-like .Iadd.circumferential .Iaddend.crimps along the length
thereof on both sides of said tubular body, said wave-like crimps
defining a crimp frequency of no less than 8 crimps per cm.
12. A woven textile graft of claim 11 wherein said wall thickness
is no greater than about 0.16 mm.
13. A woven textile graft of claim 12 wherein said crimps have a
generally uniform peak-to-peak amplitude not exceeding about 0.5
mm.
14. A woven textile graft of claim 13 wherein said tubular body
includes a radiopaque marker therein.
15. A woven textile graft of claim 11 wherein said tubular body may
be compressed for insertion into an endoluminal catheter.
16. A woven textile graft of claim 11 wherein said tubular graft
body is bifurcated.
Description
FIELD OF THE INVENTION
The present invention relates generally to synthetic tubular
prostheses and more particularly the present invention relates to a
flexible vascular graft formed of thinly woven textile
material.
BACKGROUND OF THE INVENTION
Textile grafts are widely used to replace or repair damaged or
diseased vessels of the body. Textile vascular grafts may be
implanted in the vascular system for the repair of arteries and
veins. Traditionally, graft implantation is conducted in a surgical
procedure requiring the body to be opened adjacent to the
implantation site. Improvements in medical procedures now
additionally permit graft implantation to be done in a less
invasive manner. Vascular endoscopic surgery permits certain grafts
to be implanted with a hollow catheter delivery system. The
catheter enters the vessel either percutaneously or through a small
incision. The catheter delivery system passes the graft through the
lumen of the blood vessel for deployment at the desired location.
In order to minimize trauma at the site of insertion of the
catheter, it is desirable to employ the smallest diameter catheter
possible. Accordingly, a graft which is to be implanted by the
catheter delivery system would also have to be as thin as possible
so that it can be radially compressed and packed inside the lumen
of a hollow catheter for deployment in the blood vessel. As the
size of the graft dictates the size of the catheter employed,
providing a thin graft allows use of a small diameter catheter and
therefore results in less trauma during implantation.
Traditional grafts currently available, having a wall thickness of
0.25 to 0.75 mm, are designed for surgical implantation and would
not lend themselves to successful catheter delivery. Also, since
catheter delivery is typically done under a fluoroscope or other
similar x-ray type viewing mechanism, the movement of traditional
textile vascular grafts during deployment cannot be
fluoroscopically viewed. Further, as with traditional surgically
implanted grafts, catheter implanted grafts must be longitudinally
flexible to conform to the shape of the vessel which it is
repairing. Also, such grafts should be capable of a certain degree
of longitudinal expansion to conform to the length of the blood
vessel which is to be replaced. Finally, the graft, once implanted
by the catheter delivery system, must readily return to its open
tubular shape and maintain that shape during use. This is
particularly important where the graft is implanted by a catheter
as the graft must be tightly compressed and packed so as to fit
within the hollow lumen of the catheter.
In order to maintain the desired flexibility, longitudinal
expansion and a certain degree of radial structural integrity, it
is known to provide pleated, wave-like corrugations or crimps along
the length of a textile vascular graft. These crimps provide
flexibility to the graft and the ability for the graft to
longitudinally expand in a spring-like manner.
An example of a traditional surgically implanted graft having
wave-like crimps or corrugations to provide flexibility, stretch
and radially support is shown in U.S. Pat. No. 3,142,067. As can be
seen in the '067 patent, these wave-like crimps or corrugations
have a relatively large amplitude so as to impart the desired
degree of flexibility, stretch and structural integrity to the
graft. Such large crimps in the wall of the graft presents an
irregular profile of the graft wall with a relatively large
difference between the major and minor diameter thereof. This area
is susceptible to thrombus and plaque formation and build-up which
is undesirable in a vascular graft.
It is therefore desirable to provide an improved thinly woven
textile graft which exhibits sufficient spring-like elasticity and
flexibility and which may be compressed in a manner which permits
catheter implantation into a blood vessel.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thinly woven
textile prosthetic implant capable of being catheter implanted into
a body lumen.
It is a further object of the present invention to provide a thinly
woven textile graft having a fabric thickness not exceeding about
0.16 mm and having a pattern of fine crimps therealong.
It is a still further object of the present invention to provide a
thinly woven textile graft having a pattern of finely spaced
wave-like crimps therealong wherein the peak-to-peak amplitude of
the wave-like crimps does not exceed 0.5 mm.
In the efficient attainment of these and other objects, the present
invention provides a woven textile prosthetic implant including an
elongate tubular body formed of a woven fabric having a fabric
thickness which is no greater than about 0.16 mm. The tubular body
includes a series of longitudinally spaced wave-like generally
uniform crimps along the length thereof. The crimps have a crimp
frequency of no less than about 6 crimps per centimeter of body
length.
As further described by way of the preferred embodiment herein, the
wave-like generally uniform crimps include a peak-to-peak amplitude
which is no greater than about 0.5 mm. This reduces the area in
which thrombus formation may take place.
Additionally, the present invention specifically provides an
intraluminally implantable graft having a wall thickness
sufficiently thin such that the graft may be radially compressed
for insertion into a delivery catheter for catheter
implantation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows schematically, in partial section, a conventionally
formed prosthetic graft.
FIG. 2 shows schematically, in partial section, a prosthetic graft
formed in accordance with the present invention.
FIG. 3 shows schematically, in partial section, the present
invention embodied in a bifurcated design.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides an improved textile prosthetic
implant. Specifically the preferred embodiment of the present
invention is directed towards an implantable graft which is used to
replace a damaged section of a body vessel such as a blood vessel.
However, the present invention need not be limited thereto. A
prosthetic implant in accordance with the present invention may be
used intraluminally to support any diseased or otherwise damaged
body vessel.
Referring to FIG. 1, a conventional vascular graft 10 is shown.
Graft 10 is a textile product formed of a woven or knitted
synthetic fabric in a manner which is well known in the graft art.
Graft 10 includes a generally tubular body 12 having opposed ends
14 and 16 which define therebetween an open lumen 18 which permits
passage of blood once the graft 10 is implanted in the blood
vessel. As graft 10 is designed to repair or replace a damaged or
missing blood vessel, typically in a surgical procedure, the graft
must be suitably pliable to adapt to the configuration of the
vessel into which it is being implanted and also must be flexible
enough to be handled and manipulated by the surgeon. As important,
once the graft 10 is implanted, the graft must maintain a tubular
configuration so that lumen 18 remains open allowing the passage of
blood.
In order to enhance the pliability, ease of handling and structural
stability of the tube, it has been known to provide tubular graft
10 with a series of wave-like crimps 20 along the body thereof.
Crimps 20 follow a generally sinusoidal wave-like pattern
continuously along the length of graft 10. Crimps 20 may be
imparted to graft 10 in one of a number of well-known techniques.
For instance, the uncrimped tubular graft may be compressed over a
mandrel and then by an application of heat, the crimp pattern will
take a set. Other techniques such as disposing graft 10 over a
screw-threaded mandrel and heating the mandrel, may also impart a
desired crimp-like pattern to the graft. Regardless of the
technique used to form the wave-like crimps, the number and size of
crimps on any particular graft is limited by the fabric or wall
thickness of the graft. Where the wall thickness of the graft is
relatively thick, say greater than 0.20 mm, successive crimps
cannot be closely spaced. That is, the graft cannot have finely
pitched crimps. Thus, it can be appreciated that the relatively
thickness of the fabric prevents the waves from being closely
compacted. Accordingly in order to establish the longitudinal
flexibility needed, as well as to impart sufficient tubular
integrity, it is necessary to provide wave-like crimps having a
relatively large amplitude. The amplitude of the wave, which is
dictated by the thickness of the fabric, permits the graft to be
longitudinally stretched so as to conform to the portion of the
blood vessel which must be replaced or repaired. Further, such
large amplitude crimps permit the graft to be easily flexed to
permit ease of implantation and also provide a certain degree of
structural stability to maintain the graft in an open tubular
configuration.
However, when employing the graft as a vascular graft, the large
amplitudes of the crimps have a tendency to promote the formation
of thrombus and plaque build-up between the crimps which may be
detrimental to the long-term patency of the graft. Further, the
relatively large amplitude crimps provide a significantly more
irregular profile of the graft wall which can undesirably increase
the amount of turbulence created within the vessel.
Heretofore attempts to provide a graft with finer pitched crimps of
lower amplitude have been found to be unacceptable for usage. Thick
wall grafts having finer crimps and/or crimps of lower amplitude do
not exhibit a sufficient pliancy, spring-like elasticity and
structural integrity to be suitable for implantation.
Referring now to FIG. 2, the graft of the present invention may be
described. Graft 30 is an elongate generally tubular member formed
of woven synthetic fibers such as polyester. However it may be
appreciated that other materials, as well as other forming
techniques such as knitting may also be employed. Graft 30 includes
a tubular body 32 having opposed ends 34 and 36 which define
therebetween an open lumen 37. Graft 30 defines a generally tubular
fabric wall 35 having a fabric thickness not exceeding about 0.16
mm.
An example of a graft formed in accordance with the present
invention may be formed from a plain weave tubular fabric having a
warp yarn of 50 denier, 48 filament flat polyester and weft yarn of
50 denier, 48 filament flat polyester. The ends per inch would be
188 per layer while the picks per inch would be 88 per layer. The
fabric so formed would have a wall thickness of approximately 0.12
mm. After weaving into a tubular graft, the graft would be scoured
to remove dirt, oil and other processing agents. The material may
be then heat set to stabilize the graft. Heat setting can be
accomplished in one of many conventionally known techniques such as
heating in a steam autoclave or a conventional oven. The tubular
fabric can also be heat set on smooth mandrels to precisely set the
diameter and to remove any creases or wrinkles. As above described,
the grafts may then be crimped to impart longitudinal compliance
and radial support.
As the grafts of the present invention have a fabric wall thickness
which is much thinner than grafts presently conventionally
available, a finer crimp pattern may be imparted to graft 30 of the
present invention. Crimp pattern 40 shown in FIG. 2 includes a
series of wave-like crimps 38 therealong. Crimps 38 may be imparted
on a finer pitch as the relatively thin fabric would not impede
such fine pinch crimping.
It has been found that the maximum number of crimps that can be
imparted to a tubular graft follows the equation:
C=[2(t+10)].sup.-1 where C is the number of crimps per centimeter
of length of the tube and t is the fabric or wall thickness of the
graft.
Thus, a graft having a maximum fabric or wall thickness of 0.16 mm
could be crimped to a pitch of about 33 crimps per centimeter. By
permitting such a fine crimp pattern along the length of tubular
graft 30, the amplitude of the crimps can be reduced without
significantly reducing the longitudinal flexibility or structural
stability of the graft. It has been found that forming a graft in
accordance with the present invention, the amplitude, measured
peak-to-peak, of the wave-like crimp pattern can be reduced to no
greater than 0.5 mm. A crimp pattern having such a small amplitude
greatly reduces risk of thrombus or plaque formation on the
interior of the graft.
The thinly woven graft of the present invention may be radially
compressed for insertion within the lumen of the catheter (not
shown) for catheter implantation within a body vessel. The thin
construction of the graft of the present invention permits such
catheter implantation. The above described example permits use of a
small diameter endoluminal catheter which tends to reduce trauma at
the insertion site. In the preferred example describe above,
catheters such as an 8 cm long balloon, PE-MT balloon angioplasty
catheter manufactured by Meditech-Boston Scientific, Inc. or a 10
mm diameter by 4 cm long OLBERT.RTM. balloon catheter manufactured
by Meadox Surgimed A/S may be employed for introducing and
implanting graft 30.
Once deployed, the graft 30 must maintain its longitudinal
flexibility as well as return to its tubular open lumen
configuration. The particular pattern of crimps employed with the
present invention permits such longitudinal flexibility and
structural integrity without increasing the graft thickness as
measured both by fabric wall thickness and as measured between the
peak-to-peak amplitude of the wave-like pattern of crimps.
In addition, as graft 30 is designed to be catheter implanted it is
generally desirable to provide means for viewing the implanted
graft fluoroscopically. Graft 30 may include a radiopaque guideline
or marker. As shown in FIG. 2, marker 45 may extend the length of
graft 30. Other patterns for marker 45 may also be employed.
Radiopaque marker 45 assists the surgeon to visualize the graft
both during and after implantation. The marker 45 would help show
the surgeon that the graft is properly positioned. Also, it will
indicate whether the graft has dilated or collapsed after
implantation. Further, during endoscopic implantation, marker 45
may be used to assist in the proper positioning of the graft.
As is well known, radiopaque guidelines or markers may be formed
from metallic fibers such as stainless steel or titanium. Also, one
or more polymeric fibers may be coated or filled with radiopaque
particles.
The present invention is not limited to the graft shape show in
FIG. 2, other graft configurations are within the contemplation
thereof. For example, referring to FIG. 3, a bifurcated graft 50,
may also be formed in accordance with the present invention. Graft
50 is an elongate generally tubular member having a first end 54
having a single lumen extending therefrom. An opposed end 56 is
bifurcated into a pair of smaller tubular members 56a and 56b. A
graft of this type may be used to repair and replace a main vessel
and branch vessels. In accordance with the present invention graft
50 is crimped in a manner described above to impart longitudinal
flexibility, structural integrity and spring-like compliance.
Various changes to the foregoing described and shown structures
would now be evident to those skilled in the art. Accordingly, the
particularly disclosed scope of the invention is set forth in the
following claims.
* * * * *