U.S. patent application number 09/366419 was filed with the patent office on 2002-12-26 for appliance collapsible for insertion into a human organ and capable of resilient restoration.
Invention is credited to INOUE, KANJI.
Application Number | 20020198586 09/366419 |
Document ID | / |
Family ID | 25111040 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020198586 |
Kind Code |
A1 |
INOUE, KANJI |
December 26, 2002 |
APPLIANCE COLLAPSIBLE FOR INSERTION INTO A HUMAN ORGAN AND CAPABLE
OF RESILIENT RESTORATION
Abstract
An artificial blood vessel A comprises a pair of discrete end
wire rings 10.sub.1, 10.sub.2, a tubular cover 7 made of a sheet of
flexible, tensile material which connects the end wire rings
10.sub.1, 10.sub.2, and a plurality of intermediate wire rings 12
arranged spaced apart between the end wire rings 10.sub.1, 10.sub.2
and circumferentially fixed to the cover 7 by suturing or with
adhesive. All of the rings are located on the outside of the cover.
To implant the vessel A via a catheter, a plurality of dividing
points 41.sub.1, 43.sub.1 which bisect the circumference of the
front end wire ring 10.sub.1 are pulled forward while the movement
of the midpoints 42.sub.1, 44.sub.1 between the dividing points
41.sub.1, 43.sub.1 following the movement of the dividing points
41.sub.1, 43.sub.1 is restrained by the projections 18c on a
tapered surface 18d of a funneled tube 18 so as to fold the front
end wire ring 10.sub.1 into a wavy shape, with the dividing points
41.sub.1, 43.sub.1 forming forwardly directed peaks and the
midpoints 42.sub.1, 44.sub.1 forming the bottoms of forwardly
directed valleys. The dividing points of the front wire ring are
pulled farther forward so as to fold the intermediate wire rings 12
and the rear end wire ring 10.sub.2 into a regular wavy shape
having the same phase as that of the front wire ring 10.sub.1 by
the effect of restraint by the tapered surface 18d and the
projections 18c, thereby to collapse the artificial blood vessel A
as a whole into a small size for passage through the catheter. Upon
release of the artificial vessel from the catheter at the affected
portion of the blood vessel, the artificial vessel is restored to
its original shape. The end wire rings, the cover, and the
intermediate wire rings alone keep the shape of the artificial
vessel.
Inventors: |
INOUE, KANJI; (KYOTO-SHI,
JP) |
Correspondence
Address: |
BANNER & WITCOFF LTD
1001 G ST NW
11TH FLOOR
WASHINGTON
DC
200014597
|
Family ID: |
25111040 |
Appl. No.: |
09/366419 |
Filed: |
August 4, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09366419 |
Aug 4, 1999 |
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08777717 |
Dec 20, 1996 |
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|
5976179 |
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08777717 |
Dec 20, 1996 |
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08411670 |
Apr 12, 1995 |
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Current U.S.
Class: |
623/1.13 ;
623/1.2 |
Current CPC
Class: |
A61F 2/07 20130101; A61F
2/9522 20200501; A61F 2/89 20130101; A61F 2/95 20130101; A61F
2220/005 20130101; A61F 2220/0075 20130101; A61F 2002/075 20130101;
A61F 2/9525 20200501; A61F 2/86 20130101; A61F 2002/825 20130101;
A61F 2/966 20130101; A61F 2002/9511 20130101; A61F 2230/0067
20130101 |
Class at
Publication: |
623/1.13 ;
623/1.2 |
International
Class: |
A61F 002/06 |
Claims
1. An appliance to be implanted wherein a plurality of elastically
foldable wire rings are arranged spaced apart from each other and
are interconnected by a tubular cover formed with a flexible
tensile sheet, characterized by that said wire rings alone are made
of metal and all remaining parts of said appliance are made of
nonmetal material which is flexibly deformable to follow a folding
movement of the wire rings.
2. The appliance to be implanted described in claim 1, wherein said
wire rings comprise a pair of end wire rings, each of which is
discretely arranged and interconnected by said cover, and an
intermediate wire ring which is arranged between the end wire rings
and fixed to the cover at specified positions on the circumference
thereof.
3. The appliance to be implanted described in claim 1, wherein said
wire rings are mainly made of Ti--Ni alloy.
4. The appliance to be implanted described in claim 2, wherein said
wire rings are mainly made of Ti--Ni alloy.
Description
[0001] This application is a divisional of application Ser. No.
08/77,717, filed Dec. 20, 1996, which is a continuation-in-part of
application Ser. No. 08/411,670, filed Apr. 12, 1995, now
abandoned, which is a U.S. national phase application of
PCT/JP93/01171, filed Aug. 20, 1993.
FIELD OF THE INVENTION
[0002] This invention relates to appliances for medical treatment
and, more particularly, to an appliance collapsible for insertion
into a human organ and capable of resilient restoration (which will
be referred to as "the appliance to be implanted" in this
specification and claims), to a method of collapsing the appliance
to be implanted, and to a device for introducing the collapsed
appliance to be implanted into a catheter.
PRIOR ART
[0003] The artificial blood vessel is an example of the appliance
to be implanted. At present, treatment of, for example, aortic
aneurysm is conducted by implanting an artificial blood vessel. In
particular, the portion of a blood vessel which has an aneurysm is
removed by resection, and an artificial blood vessel is implanted
in place of the resected portion and connected to the remaining
blood vessel by suturing or the like.
[0004] The above-mentioned method of surgically implanting
artificial blood vessels for treatment of aortic aneurysm, however,
is highly dangerous. Especially, an emergency operation for
treatment of a ruptured aneurysm has a low life-saving rate, and an
operation of dissecting aortic aneurysm is difficult to conduct and
has a high death rate.
[0005] Therefore, in order to treat these diseases without a
surgical operation, a method has been developed of introducing into
a catheter an appliance such as an artificial blood vessel in
collapsed condition into a human organ such as a blood vessel, and
transporting the appliance to a desired position such as an
affected or constricted portion thereof, where the appliance is
released so as to be expanded and implanted there with
accuracy.
[0006] The appliance to be implanted comprises a pair of end wire
rings and a frame mainly composed of connecting wires which connect
the above-mentioned end wire rings. The appliance is pushed at the
rear end wire ring into a catheter and transported to a desired
organ in a human body. In order to transport the appliance, the
force applied to the rear end wire ring should be transmitted to
the front end wire ring. Therefore, it is indispensable that the
frame should be made of comparatively strong metal and that the
appliance should have the frame as an inevitable constructing
element. If the above-mentioned frame is used, interference is
likely to take place between the end wire rings and the frame and
prevents the end wire rings from being folded, which makes it
difficult to fold the end wire rings into a regular wavy shape. The
difficulty in folding the end wire rings will make it difficult to
collapse the whole appliance to be implanted into a small size.
[0007] As the end wire rings have an elastic limit, if a force
exceeding the elastic limit is applied to the rings, the end wire
rings folded for insertion into a catheter suffer plastic
deformation so that the end wire rings may not be restored to a
proper shape when released at an objective position in a human
organ. The distortions caused by the plastic deformation may give
rise to sliding resistance and prevent the appliance to be
implanted from traveling in a catheter, thereby to make it
difficult or impossible for the appliance to be transported to a
desired position.
[0008] In addition, a frame, if used in the appliance to be
implanted, is likely to hinder the appliance from being implanted
in an appropriate shape into a human organ. Especially, in placing
the appliance into a bent portion of a human organ, the frame may
be deformed into a flat shape because different parts of the frame
interfere with each other. Even if the appliance has been
implanted, it may not be able to function as it is intended to. In
the conventional frame, the wire of the wire rings provided at the
opposite ends of the frame is exposed, so that the inner wall of a
human organ may be scratched and damaged by the wire and blood is
likely to leak out from the end wire rings because the rings are
not adhered closely to the inner wall of the human organ.
[0009] Even though a check valve is provided at the outer end of a
catheter whose front end has been inserted into the blood vessel of
a human body beforehand, the check valve must be temporarily opened
when the collapsed appliance is introduced into the catheter,
thereby to cause a lot of bleeding. It is therefore desirable to
provide means for preventing bleeding.
[0010] The present invention has been accomplished to solve the
above-mentioned problems. The object of the invention is to develop
an appliance of non-frame type, which can solve all of the
above-mentioned problems.
SUMMARY OF THE INVENTION
[0011] The method of collapsing the appliance to be implanted in
accordance with the invention is characterized by that the
appliance to be implanted comprises a pair of discrete end wire
rings, a tubular cover made of a sheet of flexible, tensile
material which connects the above-mentioned end wire rings, and a
plurality of intermediate wire rings arranged spaced apart between
the above-mentioned end wire rings and circumferentially fixed to
the above-mentioned cover by suturing or with adhesive; and that
the method comprises the steps of: pulling forward the front end
wire ring at a plurality of dividing points which equally divide
the circumference of the front end wire ring while restraining the
midpoints between each adjacent two dividing points by a tapered
surface from moving forward following the forward movement of the
dividing points, thereby to fold the front end wire ring into a
wavy shape with the dividing points forming forwardly directed
peaks and the midpoints forming the bottoms of forwardly directed
valleys, and pulling the dividing points of the front wire ring
farther forward thereby to fold the intermediate wire rings and the
rear end wire ring into a wavy shape having the same phase as that
of the front end wire ring by the effect of restraint with the
tapered surface.
[0012] A loop for a pull string to be passed through may be formed
at each of the dividing points on the front end wire ring so that a
front pull string may be passed through each of the loops and
pulled forward. In particular, a common pull string may
advantageously be passed through a plurality of loops so that the
dividing points may be gathered together by pulling the common
front pull string. A funneled guide tube whose bore diameter is
gradually reduced toward its forward end may be used to gather the
dividing points and the midpoints by pulling forward the dividing
points on the front end wire ring of the appliance to be implanted
inserted into the funneled guide tube through its rear opening. In
particular, resiliently deformable projections can be formed on the
tapered inner surface of the funneled guide tube so as to bring the
midpoints into contact with the projections thereby to effectively
restrain the midpoints from moving forward following the movement
of the dividing points and cause the midpoints to approach to each
other. The end wire rings can be circumferentially covered with
elastic protective material.
[0013] The appliance to be implanted in accordance with the
invention is characterized by a pair of discrete end wire rings
which are resiliently foldable and provided at opposite ends; that
the end wire rings are connected by only a tubular cover made of a
sheet of flexible, tensile material; and that a plurality of
intermediate wire rings are arranged between the above-mentioned
end wire rings and fixed to the above-mentioned cover at
appropriate points on the circumference thereof by suturing or with
adhesive.
[0014] The flexible, tensile sheet may be made, for example, of
warps extending in the axial direction of the appliance to be
implanted woven with wefts extending in the circumferential
direction thereof. The warps are made of mono-filament of polyester
capable of keeping its shape and the wefts are made of
multi-filament of polyester having waterproofness.
[0015] The tubular cover may be in the form of bellows. Especially,
the end wire rings may advantageously be connected by restraining
strings so as to prevent the bellows from overstretching to exceed
a given limit. The end wire rings can be circumferentially covered
with an elastic protective material. Further, thorns can be
provided on the circumference of at least one of the wire rings so
as to stick into a human organ to be embedded therein. The thorns
may be effectively formed by curving a wire into a loop, crossing
the opposite end portions of the wire, and fixing the crossing
point, thereby to form the opposite end portions into the
thorns.
[0016] The device for introducing the appliance to be implanted in
a collapsed state into a catheter in accordance with the invention
comprises an attachment having a flexible check valve which closes
an open end thereof and fixed to an open end of a catheter, and a
cartridge removably attachable to the above-mentioned attachment
and having an open end closed by a flexible check valve and a front
end portion connected to the above-mentioned catheter when the
cartridge is attached to the attachment; and by that the check
valve of the cartridge is pushed open to introduce the appliance to
be implanted into the cartridge, and while the check valve of the
cartridge is kept nearly closed, the front end portion of the
cartridge is inserted into the catheter by pushing the check valve
of the attachment open.
[0017] The bore diameter of the attachment of the catheter is made
larger than that of the open end of the catheter, so that when the
cartridge is attached, the bore of the front end portion of the
cartridge may be smoothly connected to the open end of the catheter
through the attachment of the catheter.
[0018] With the method of collapsing the appliance to be implanted
in accordance with the invention, the operation of collapsing the
appliance can be conducted with ease and accuracy. It is difficult
to fold the front end wire ring into such a small size that can be
contained in a catheter just by applying non-directional external
force thereto. However, if the dividing points which equally divide
the circumference of the front end wire ring are pulled forward
with the midpoints provided between the dividing points being
restrained by a tapered surface from moving forward following the
dividing points, the front end wire ring is folded into a wavy
shape with the midpoints serving as footholds and with the dividing
points forming forwardly directed peaks and the midpoints forming
the bottoms of forwardly directed valleys. After the front end wire
ring has been bent, the intermediate and the rear end wire rings
also are folded into a wavy shape having the same phase as that of
the front end wire ring by pulling farther forward the dividing
points on the front end wire ring to transmit the pulling force to
the intermediate and the rear end wire rings through the tensile
cover, and by simultaneously restraining the intermediate and the
rear end wire rings by means of a tapered surface, thereby to
collapse the whole appliance into a small size with ease.
[0019] What should especially be referred to is that the method of
collapsing the appliance to be implanted in accordance with the
invention is characterized by that a pair of end wire rings
provided at the opposite ends of the appliance are connected by
only a tubular cover which is made of a sheet of flexible, tensile
material; and that the front end wire ring is pulled forward. The
conventional method, in which the rear end portion of the appliance
to be implanted is pushed to insert the appliance into a human
organ, requires a relatively strong frame made mainly of connecting
wire rings in order to transmit the force applied to the rear end
of the appliance to the forward portion thereof. However, the
invention is based on pulling the front end wire ring forward,
thereby to make it possible to insert the appliance with ease even
without a frame. In addition, the cover follows the movement of the
wire rings being folded and is transformed into any desired shape,
thereby to avoid interference between the wire rings and the frame.
Consequently, by the method of collapsing the appliance in
accordance with this invention it is possible to fold each of the
wire rings into a wavy shape and to collapse the whole appliance
into a small size with ease.
[0020] The operation of folding the wire rings is conducted with
ease by forming loops for a pull string to be passed through at the
dividing points on the front end wire ring and pulling forward a
front pull string passed through the loops. In particular, a common
front pull string passed through a plurality of loops is more
effective to change the pulling force to a force to fold the wire
rings because the dividing points are gathered toward each
other.
[0021] In collapsing the appliance, a funneled guide tube whose
bore diameter is gradually reduced in the forward direction may
advantageously be used, so that the dividing points and midpoints
of the wire rings are gathered toward each other as the appliance
to be implanted is inserted farther into the funneled tube, thereby
to collapse the appliance as a whole into a small size. If
projections resiliently deformable and engageable with the
midpoints are formed on the tapered inner surface of the funneled
guide tube, the midpoints are urged toward each other by the
counterforce from the projections, and a space is formed between
the end wire rings and the funneled guide tube, thereby effectively
to prevent the appliance and the funneled guide tube from closely
contacting each other to increase sliding resistance therebetween
so that the appliance cannot be moved in the guide tube.
[0022] Elastic protective material circumferentially covering the
end wire rings is useful to prevent the appliance from being
damaged when collapsed into a small size. If the wire ring is bent
to such a degree that the elastic limit is exceeded, not only does
it becomes difficult for the ring to be restored to its original
annular shape but also it becomes impossible to move the ring in a
catheter due to the bent portion being caught in the catheter.
However, if protective material is provided, the material disperses
the tension which would otherwise be exerted locally on the
dividing points when the points are strongly pulled, thereby to
prevent tension from being applied locally to the dividing points
so that the elastic limit is exceeded to bend the wire ring. The
protective material prevents the front end wire ring from being
plastically deformed, and provides it with a proper capability of
resilient restoration to an annular shape and of traveling smoothly
in a catheter, thereby to fold the front end wire ring into a
regular wavy form.
[0023] The appliance having no frame, as mentioned above, properly
functions as an artificial blood vessel. The appliance in
accordance with the invention has a feature that the cover itself
is tensile and is held by the wire rings at both ends and the
intermediate wire rings at appropriate points thereof. Therefore,
when the whole is appliance is released from the state of being
collapsed and each of the wire rings are resiliently restored to
the annular shape, the cover is resiliently restored to its
original proper tubular shape. The conventional appliance having a
frame is likely to be deformed flatly because of mutual
interference of the component parts when it is arranged in a bent
portion of a human organ. However, the appliance of the invention
having no frame can be transformed into any desired shape so as to
conform to different shapes of a human organ.
[0024] A sheet woven with warps and wefts, in which the warps are
made of monofilament of polyester and the wefts are of
multi-filament of polyester, makes the whole appliance flexible. In
addition, the warps provide the cover of the appliance with tensile
strength in the axial direction and a capability of keeping its
shape, and the wefts make the sheet closely woven and increase its
waterproofness.
[0025] If the sheet of the cover is in the form of bellows, the
whole appliance is bent smoothly, thereby to improve the condition
of the appliance when implanted into a human organ. If the sheet of
the cover is in the form of bellows, restraining strings connecting
the front and the rear end wire rings can prevent the bellows from
stretching to such a degree that the elastic limit is exceeded to
be flat.
[0026] The elastic protective material circumferentially covering
the wire rings can prevent, as mentioned previously, not only the
wire rings from being plastically deformed when folded into a small
size but also the inner wall of a human organ from being damaged by
direct contact with the wire rings. The protective material also
acts as a seal to attach both ends of the appliance to be implanted
tightly to the inner wall of a human body, thereby to effectively
prevent leakage of blood through the ends of the appliance when
implanted.
[0027] When thorns are provided projecting from the wire rings,
they stick into the inner wall of a human organ to be embedded
therein so that the whole appliance is fixed to the human organ.
Therefore, the thorns effectively prevent the appliance from being
displaced or even carried by blood flow downstream in a blood
vessel. The thorns are formed with ease by curving a wire into a
loop, crossing both end portions of the wire, and fixing the
crossed parts with a string or the like, even though the material
of the wire is difficult to weld. The thorns thus formed reliably
function as mentioned above for a long time.
[0028] In addition, with the device for introducing a collapsed
appliance to be implanted into a catheter in accordance with the
invention it is possible to introduce the appliance to be implanted
smoothly into a catheter. In particular, the appliance to be
implanted is inserted into the cartridge by pushing the check valve
open as far as the appliance reaches a position at which it is
almost completely contained in the cartridge. Before or after the
insertion, the cartridge is attached to the attachment provided at
the open end of the catheter, and then the appliance is pulled
farther forward in that condition so as to be introduced into the
catheter through the attachment. When the check valve in the
attachment is opened, the check valve of the cartridge is closed,
so that blood flowing into the cartridge is prevented from flowing
outside the body through the cartridge without fail. In addition,
if the appliance is to be inserted directly into the catheter, the
appliance cannot be inserted smoothly because of the catheter and
the appliance being flexible, and the catheter is bent by the force
applied to the appliance, thereby to block the passage through
which the appliance is to be inserted or to make the catheter
fragile. On the other hand, if the appliance is to be inserted into
the catheter through the attachment and the cartridge, by making
the attachment and the cartridge strong and of such a shape as to
be handled with ease it is possible to solve the problem of the
catheter being bent or otherwise deformed, thereby to enable the
appliance to be introduced into the catheter smoothly and with
ease. If the bore diameter of the attachment is made bigger than
that of the catheter and the bore diameter of the front end of the
cartridge is smoothly connected to that of the open end of the
catheter when the cartridge is attached to the catheter, it is
possible to prevent the appliance to be implanted from being
temporarily swollen in the attachment and caught therein, and to
introduce the appliance to be implanted deep into the catheter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a perspective view of an artificial blood vessel
used in one embodiment of the invention.
[0030] FIG. 2 is a vertical cross-sectional view of part of the
artificial blood vessel.
[0031] FIG. 3 is a perspective view of a device for transporting
the artificial blood vessel, used in the embodiment.
[0032] FIG. 4 is a perspective view of a device for introducing the
artificial blood vessel, used in the embodiment.
[0033] FIG. 5 is an enlarged vertical cross-sectional view of part
of the attachment shown in FIG. 4.
[0034] FIG. 6 is an enlarged vertical cross-sectional view of part
of the cartridge shown in FIG. 4.
[0035] FIG. 7 is a perspective view of the artificial blood vessel
through which the device for transporting the artificial blood
vessel is loosely inserted.
[0036] FIG. 8 is a perspective view showing a step to hold the
artificial blood vessel by means of the device for transporting the
artificial blood vessel.
[0037] FIG. 9 is a perspective view showing a step to hold the
artificial blood vessel by means of the device for transporting the
artificial blood vessel.
[0038] FIG. 10 is an enlarged perspective view showing part of the
artificial blood vessel kept by the device for transporting the
artificial blood vessel.
[0039] FIG. 11 is a perspective view showing a step to introduce
the artificial blood vessel into a catheter.
[0040] FIG. 12 is a perspective view showing a step to introduce
the artificial blood vessel into the catheter.
[0041] FIG. 13 is a perspective view showing a step to introduce
the artificial blood vessel into the catheter by means of the
device for introducing the artificial blood vessel.
[0042] FIG. 14 shows the front end wire ring of the artificial
blood vessel being folded.
[0043] FIG. 15 shows the front end wire ring of the artificial
blood vessel being folded.
[0044] FIG. 16 shows the front end wire ring of the artificial
blood vessel being folded.
[0045] FIG. 17 shows the front end wire ring of the artificial
blood vessel being folded in a funneled tube.
[0046] FIG. 18 shows the intermediate wire rings and the rear end
wire rings of the artificial blood vessel being folded.
[0047] FIG. 19 shows the collapsed artificial blood vessel.
[0048] FIG. 20 shows the artificial blood vessel being inserted
into the cartridge.
[0049] FIG. 21 shows the artificial blood vessel inserted into the
cartridge.
[0050] FIG. 22 shows the artificial blood vessel transported from
the cartridge to the attachment.
[0051] FIG. 23 is a cross-sectional view showing the artificial
blood vessel transported to the affected portion.
[0052] FIG. 24 shows a step to release the artificial blood vessel
at an affected part in a blood vessel.
[0053] FIG. 25 shows a step to release the artificial blood vessel
at the affected part in the blood vessel.
[0054] FIG. 26 is a cross-sectional view showing the artificial
blood vessel released at the affected portion in the blood
vessel.
[0055] FIG. 27 shows a step to expand the artificial blood vessel
by means of a balloon catheter.
[0056] FIG. 28 shows the principle of another embodiment of the
invention.
[0057] FIG. 29 shows the principle of a different embodiment of the
invention.
[0058] FIG. 30 is a perspective view corresponding to FIG. 12 of a
further different embodiment of the invention.
[0059] FIG. 31 is an enlarged perspective view of part of the above
embodiment.
[0060] FIG. 32 is an enlarged cross-sectional view along the line
Z-Z in FIG. 31.
[0061] FIG. 33 is a perspective view corresponding to FIG. 31 of a
modified form of the embodiment.
[0062] FIG. 34 is a partial cross-sectional view of an artificial
blood vessel in accordance with the invention, positioned within an
affected part of a blood vessel.
[0063] FIG. 35 is a partial cross-sectional view of a related art
artificial blood vessel positioned within an affected part of a
blood vessel.
[0064] FIG. 36 is a partial cross-sectional view of a modified
embodiment of the inventive artificial blood vessel.
[0065] FIG. 37 is a schematic close-up view of a cover material
usable in an artificial blood vessel in accordance with the
invention.
[0066] FIG. 38 is an end elevational view of an artificial blood
vessel representing another modified embodiment of the
invention.
[0067] FIG. 39 is an end elevational view of an artificial blood
vessel representing a further modified embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0068] The invention will be described in detail with reference to
the embodiments thereof shown in the accompanying drawings.
[0069] The artificial blood vessel A as the appliance to be
implanted, which is collapsed by the method in accordance with this
invention, comprises, as shown in FIG. 1, a cover 7, end wire rings
10.sub.1, 10.sub.2 and intermediate wire rings 12.
[0070] The cover 7, as shown in FIG. 2, consists of a flexible,
tensile sheet shaped into a tube of bellows, the diameter of which
generally corresponds to the normal diameter of that portion of the
human blood vessel at which the artificial blood vessel A is to be
implanted. The sheet of the cover 7 is, for example, of warps
extending in the axial direction of the artificial blood vessel A
woven with wefts extending in the circumferential direction
thereof, wherein the warps are of mono-filament made of polyester
(about 15 denier) and the wefts are of multi-filament made of a
plurality of superfine filaments (about 50 denier) interwoven. The
cover 7 is coated, if necessary, with waterproof material, for
example, collagen or albumin, to prevent leakage of blood.
[0071] The end wire rings 10.sub.1, 10.sub.2, whose inner diameter
generally corresponds to that of the above-mentioned cover 7, are
axially spaced apart and arranged face to face, and are fixed to
the opposite ends of the cover 7 by suturing or with adhesive as
shown in FIG. 2. The circumferences of the end wire rings 10.sub.1,
10.sub.2 are covered with protective braid members 10a, which are
closely fixed to the end wire rings 10.sub.1, 10.sub.2 at
appropriate positions with thread, adhesive or the like.
[0072] The intermediate wire rings 12, which comprise, as shown in
FIGS. 1 and 2, one or two wire rings 12a wrapped with protective
film 12b made of cloth or the like, are arranged axially
equidistantly between the end wire rings 10.sub.2 and 10.sub.2, and
fixed to the cover 7 at appropriate positions on the circumference
thereof with thread, adhesive or the like. The above-mentioned end
wire rings 10.sub.2, 10.sub.2 and the intermediate wire rings 12
help keep the tubular shape of the cover 7. Thorns 12a.sub.1 are
formed at two diametrically opposite positions on each of those two
intermediate wire rings 12 each of which comprises two wire rings
12a, so that the thorns 12a.sub.1 may stick into a human organ so
as to be embedded therein. In particular, the wires 12a of the
intermediate rings 12 as well as those of the end wire rings
10.sub.2, 10.sub.2 are made of Ti--Ni alloy or the like. The wires
of Ti--Ni alloy have a high resilient restoring force, but are hard
to weld. As the Ti--Ni alloy has the above-mentioned
characteristic, the thorns 12a.sub.1 are formed by forming a length
of wire 12a into a loop, whose opposite end portions are crossed so
as to provide a pair of short lengths of wire projecting from the
crossing point, which is tied with a string or the like, and the
projecting end wire portions are bent to provide the thorns
12a.sub.1 on the ring. In the same manner, a pair of thorns
12a.sub.1 are provided on another ring formed of a length of wire
12a. The two rings are arranged side by side, with the thorns
12a.sub.1 on one of the rings arranged diametrically opposite to
the thorns 12a.sub.1 on the other ring. The two rings 12a are
covered with a protective film 12b, through which the thorns
12a.sub.1 project outside.
[0073] As shown in FIG. 1, let it be assumed here that the
circumference of the front end wire ring 10.sub.1 to be first
introduced into the catheter 8 is bisected by two points which will
be referred to as the dividing points 41.sub.1, 43.sub.1, and the
two midpoints between the two dividing points 41.sub.1, 43.sub.1
will be referred to as the midpoints 42.sub.1, 44.sub.1. On the
circumference of the rear end wire ring 10.sub.2, those points
whose phases are the same as the dividing points 41.sub.1, 43.sub.1
and the midpoints 42.sub.1, 44.sub.1 will be referred to as the
points 41.sub.2, 43.sub.2 corresponding to the dividing points
41.sub.1, 43.sub.1 and the points 42.sub.2, 44.sub.2 corresponding
to the midpoints 42.sub.1, 44.sub.1, respectively. On the
circumference of the intermediate wire ring 12, those points whose
phases are the same as the dividing points 41.sub.1, 43.sub.1 and
the midpoints 42.sub.1, 44.sub.1 will be referred to as the points
41.sub.3, 43.sub.3 corresponding to the dividing points 41.sub.1,
43.sub.1 and the points 42.sub.3, 44.sub.3 corresponding to the
midpoints 42.sub.1, 44.sub.1, respectively. As shown in FIG. 1, a
pair of loops 13 of thread or the like are so formed that the
centers thereof are positioned at the dividing points 41.sub.1,
43.sub.1 of the front end wire ring 10.sub.1. Restraining strings
14 bridge the end wire rings 10.sub.1 and 10.sub.2 so as to prevent
the artificial blood vessel A from being stretched unnecessarily
too much along the axis thereof.
[0074] In order to implant the artificial blood vessel A of the
above-mentioned construction into a target organ of a human body, a
device B for transporting artificial blood vessels (see FIG. 3) is
used to transport the artificial blood vessel A to the target organ
of the human body through the catheter 8 and a device C for
introducing artificial blood vessels (see FIG. 4) is used to
introduce the artificial blood vessel A into the catheter 8.
[0075] The device B for transporting artificial blood vessels, as
shown in FIG. 3, comprises a flexible metallic tube 2 whose front
end portion is connected to a helical spring 2a for guiding, a side
window 1 formed adjacent the front end of the tube 2, a pair of
strings 4 having both their ends fixed to the tube 2 adjacent the
side window 1 and their middle portions formed into loops 4a, and a
length of wire 3 slidably inserted into the tube 2.
[0076] The device C for introducing artificial blood vessels, as
shown in FIG. 4, comprises an attachment 5 integrally connected to
the catheter 8 through an open end 8a thereof, and a cartridge 6
removably attached to the attachment 5. As shown in FIGS. 4 and 5,
the attachment 5 comprises a first and a second annular member 51,
52 which are internally threaded to form female screws, a third
annular member 53 which is externally threaded to form male screws
at opposite ends, which engage the above-mentioned female screws
thereby to connect the first and the second annular members 51, 52,
and a straw member 54 which liquid tightly joins the interior of
the first annular member 51 with that of the open end 8a of the
catheter 8. A check valve 55 made of elastic membrane is provided
inside the second annular member 52 to close the open end thereof.
The cartridge 6, as shown in FIGS. 4 and 6, is of generally the
same construction as the attachment 5 and comprises first and
second annular members 61, 62 which are internally threaded to
provide internal female screws, a third annular member 63 which is
externally threaded to form male screws at opposite ends, which
engage the above-mentioned female screws at opposite ends to
connect the first and second annular members 61, 62, and a straw
member 64 which projects from the first annular member 61 in the
direction of insertion. A check valve 65 made of elastic membrane
is provided inside the second annular member 62 to close the open
end thereof.
[0077] As shown in FIG. 4, the straw member 64 of the cartridge 6
is so constructed that the front end portion 6a thereof is
removably fitted into the rear end portion 5a of the attachment 5
which is connected integrally to the open end 8a of the
above-mentioned catheter 8. In particular, as shown in FIGS. 4, 5,
and 6, the bore diameter di of the straw member 54 of the
attachment 5 is a little larger than the bore diameter d.sub.2 of
the straw member 64 of the cartridge 6, and the length L.sub.2 of
the straw member 64 is approximately equal to the full length
L.sub.1 of the attachment 5. Similarly the bore diameter d.sub.2 of
the straw member 64 of the cartridge 6 is approximately equal to
the bore diameter d.sub.3 of the open end 8a of the catheter 8.
When the cartridge 6 is inserted a certain length into the
attachment 5, the straw member 64 is inserted into the straw member
54 so that the bore d.sub.2 of the straw member 54 is smoothly
connected to the bore d.sub.3 of the open end 8a of the catheter 8.
The above-mentioned check valves 55, 65 are made of elastic
membrane, in each of which a normally closed hole, not shown in
drawings, is formed.
[0078] A funneled tube 18, as shown in FIG. 4, is provided as a
guide tube to help collapse the artificial blood vessel A. The
funneled tube 18 is provided with an inlet opening 18a of an
enlarged diameter at the rear end portion, through which the
tubular artificial blood vessel A is inserted into the funneled
tube 18. The funneled tube 18 is gradually reduced in diameter from
the inlet opening 18a to end in a tubular connector 18b of a
smaller diameter at the front end portion thereof, so that the tube
18 has a tapered inner surface 18d. The funneled tube 18 is
removably connected to the cartridge by inserting the front
connector 18b into the rear end portion 6b of the cartridge 6.
Elastically transformable projections 18c are provided at regular
intervals from the rear end portion to the front along two specific
generatrices on the tapered inner surface 18d of the funneled tube
18. When the artificial blood vessel A travels along the tapered
inner surface 18d of the funneled tube 18, the projections 18c are
elastically transformed by the vessel A to exert a resilient
counterforce to the artificial blood vessel A thereby to contract
vessel A.
[0079] In order to form the projections 18c with ease, as shown in
FIG. 4, several pairs of holes 18e are formed on the tapered wall
18d of the funneled tube 18, and a wire 18f is inserted through one
of each pair of holes 18e and drawn out through the other of the
pair of holes 18e so as to form a looped projection 18c erect on
the inner side of the tapered inner surface 18d, with appropriate
portions of the wire 18f being tied with a string 18g.
[0080] The operations of collapsing the artificial blood vessel A
and implanting it into a target portion (an affected part 26) of a
blood vessel 9 by means of the device B for transporting artificial
blood vessels and the device C for introducing artificial blood
vessels of the above-mentioned constructions, will now be described
below.
[0081] First, the tube 2 is inserted through the artificial blood
vessel A as shown in FIG. 7, and each of a pair of strings 4 is
passed through each loop 13 of the artificial blood vessel A as
shown in FIG. 8, and the looped portions of the strings 4 overlap
as shown at 4a. Next, a wire 3 has its forward end taken out of the
side window 1 as shown in FIG. 9, and the overlapped portions of
the looped portions 4a are hooked over the wire 3, and then the
wire 3 has its forward end inserted again into the tube 2 through
the side window 1 so as to hold the artificial blood vessel A on
the wire 3 and the tube 2 through the strings 4. Then, the
artificial blood vessel A is inserted into the cartridge 6 shown in
FIG. 4 through the funneled tube 18. In particular, the midpoints
42.sub.1, 44.sub.1 are aligned with the above-mentioned
generatrices of the funneled tube 18, with a common front pull
string 20 being passed through the loops 13 provided at the
dividing points 41.sub.1, 43.sub.1 on the front end wire ring
10.sub.1 of the artificial blood vessel A as shown in FIG. 11. A
balloon catheter 23, as shown in FIG. 12, may be used, if
necessary. The balloon catheter 23 comprises a pipe 23a, a balloon
23b formed on the front end portion of the pipe 23a, and an opening
23c provided in the rear end of the pipe 23a for air to be
introduced into or taken out of the above-mentioned balloon 23b
through the pipe 23a. The pipe 23a is loosely fitted over the tube
2 of the above-mentioned device B for transporting artificial blood
vessels. In other words, the rear portion of the device B for
transporting artificial blood vessels is drawn outside from the
rear end of the balloon catheter 23 while the front end portion of
the device is passed through the balloon 23b of the balloon
catheter 23 and exposed outside, with the portions of the catheter
23 through which the tube 2 is passed being air tightly sealed. The
rear end portion of the pipe 23a is removably connected to the tube
2 of the device B for transporting artificial blood vessels by a
fixing member 24, and the balloon catheter 23 and the tube 2 of the
device B for transporting artificial blood vessels can be moved
together as a unit longitudinally when the fixing member 24 is
fastened, and the balloon catheter 23 can be moved longitudinally
relative to the tube 2 of the device B when the fixing member 24 is
loosened. The balloon catheter 23 is so positioned that the front
end thereof is spaced about 2 to 3 cm apart from the rear end of
the artificial blood vessel A loosely fitted over the tube 2. Then
the fixing member 24 on the balloon catheter 23 is fastened to fix
the catheter 23 to the tube 2 so that the catheter 23 and the tube
2 can be moved together as a unit.
[0082] Before or after the above step, the funneled tube 18 is
attached to a cartridge 6 as shown in FIG. 13. In attaching the
funneled tube 18 to the cartridge 6, the connector 18b of the
funneled tube 18 is inserted into the annular member 62 of the
cartridge 6 so that the check valve 65 of the elastic membrane
provided inside the annular member 62 is pushed open by the
connector 18b of the funneled tube 18, and the connector 18b is
inserted a little into the straw 64 of the cartridge 6. The front
pull string 20 is inserted into the funneled tube 18 through the
rear end portion 18a thereof and withdrawn forward through the
straw 64 at the front end of the cartridge 6, with the tube 2
inserted a certain length into the funneled tube 18. Under the
condition, the front pull string 20 is pulled forward to introduce
the artificial blood vessel A into the funneled tube 18 through the
enlarged inlet opening 18a thereof.
[0083] Under the condition, as the front pull string 20 is farther
pulled, the dividing points 41.sub.1, 43.sub.1 on the front end
wire ring 10.sub.1 of the artificial blood vessel A are pulled by
the front pull string 20, as shown in FIG. 14, and the midpoints
42.sub.1, 44.sub.1 are engaged by the projections 18c provided
along the generatrices on the tapered surface 18d, so that the
front end wire ring 10.sub.1 is deformed with the dividing points
41.sub.1, 43.sub.1 approaching toward each other with the midpoints
42.sub.1, 44.sub.1 serving as footholds as shown in FIG. 15. The
midpoints 42.sub.1, 44.sub.1 are restricted by the projections 18c
and left behind the dividing points 41.sub.1, 43.sub.1, and urged
by the resilient counterforce of the projections 18c to approach
each other, thereby to cause the front end wire ring 10.sub.1 to be
folded flat as shown in FIG. 16. In short, the front end wire ring
10.sub.1 is transformed from the shape shown in FIG. 14 to the
shape shown in FIG. 15, and thence to the shape shown in FIG. 16,
with the dividing points 41.sub.1, 43.sub.1 where the loops 13 are
provided forming forwardly directed peaks and the midpoints
42.sub.1, 44.sub.1 forming the bottoms of forwardly directed
valleys, so that the front end wire ring 10.sub.1 as a whole takes
a regular wavy shape. In short, as shown in FIG. 17, the front end
wire ring 10.sub.1 is passed through the funneled tube 18 while
being farther folded. Since the cover 7 is tensile, as the front
pull string 20 is pulled forward, the pulling force is transmitted
through the cover 7 to the points 41.sub.3, 43.sub.3 on the
intermediate rings 12 corresponding to the dividing points and the
points 41.sub.2, 43.sub.2 on the rear end wire ring 10.sub.2
corresponding to the dividing points, as shown in FIG. 18. The
points 42.sub.3, 44.sub.3 on the intermediate rings 12
corresponding to the midpoints and the points 42.sub.2, 44.sub.2 on
the rear end wire ring 10.sub.2 corresponding to the midpoints are
restrained by the projections 18c when they move along the
generatrices on the tapered surface 18d, with the points 41.sub.3,
43.sub.3, 41.sub.2, 43.sub.2 corresponding to the dividing points
forming forwardly directed peaks and the points 42.sub.3, 44.sub.3,
42.sub.2, 44.sub.2 corresponding to the midpoints forming the
bottoms of forwardly directed valleys, as shown in FIG. 19, so that
the intermediate wire rings 12 and the rear end wire ring 10.sub.2
are also folded to take a wavy shape having the same phase as that
of the front end wire ring 10.sub.1. As the rings 10.sub.1 and
10.sub.2 are folded, the braid members 10a circumferentially
arranged about the end wire rings 10.sub.1, 10.sub.2 are also
folded to take a wavy shape. As the artificial blood vessel A is
collapsed, the thorns 12a.sub.1 are pushed down to extend rearward
or forward because of the above-mentioned construction.
[0084] Thus, the artificial blood vessel A inserted into the
connector 18b is introduced into the straw 64 of the cartridge 6,
as shown in FIG. 20, by pulling the front pull string 20 farther
forwardly. Under the condition, the front pull string 20 is untied
and pulled at its end so as to be withdrawn from the loops 13, and
the funneled tube 18 is withdrawn from the cartridge 6 through the
rear end portion 6b thereof. Consequently, the artificial blood
vessel A is contained in the straw 64 of the cartridge 6, as shown
in FIG. 21, and only the pipe 23a of the balloon catheter 23
through which the tube 2 is passed is exposed outside through the
rear end portion 6b of the cartridge 6 with the check valve 65
opened a little.
[0085] On the other hand, the catheter 8 has been previously
inserted through, for example, the coxal artery adjacent the groin
F into the blood vessel 9 as far as the front end of the catheter 8
has been positioned a little beyond the affected portion 26 such as
an aneurysm of the aorta. The attachment 5 connected to the open
end 8a of the catheter 8 is, as shown in FIG. 22, exposed outside
the body. Next, the cartridge 6 into which the artificial blood
vessel A has been inserted is pushed into the attachment 5 through
the rear end portion 5a thereof with the check valve 5 opened, and
the straw 64 of the cartridge 6 is positioned so that the front end
6a thereof is smoothly connected to the inner surface of the open
end 8a of the catheter 8. Under the condition, the pipe 23a of the
balloon catheter 23 is gripped and the balloon catheter 23 is
pushed so as to be inserted gradually deeply into the catheter 8.
As the tube 2 is connected to the balloon catheter 23 through the
fixing member 24 and the artificial blood vessel A is held by the
tube 2, movement of the balloon catheter 23 causes the artificial
blood vessel A to be transported gradually to the deep position in
the body. The balloon catheter 23 is pushed until the front end of
the tube 2 is positioned at the front end of the catheter 8, as
shown in FIG. 23. At this time the artificial blood vessel A is
positioned at the affected portion 26 as the target position. Then,
as the catheter 8 is withdrawn as shown in FIG. 24, with the
balloon catheter 23 and the tube 2 into which the wire 3 is
inserted left at the objective position, the collapsed artificial
blood vessel A in the catheter 8 is released at the affected
portion 26 in the blood vessel 9 while expanding gradually from the
front end as shown in FIGS. 24, 25 and 26. The released artificial
blood vessel A is restored to its original tubular shape and urged
against the inner wall of the blood vessel 9. Then the fixing
member 24 shown in FIG. 12 is loosened to disconnect the balloon
catheter 23 from the tube 2, and the balloon catheter 23 is
advanced along the tube 2 into the artificial blood vessel A with
the tube 2 kept at the objective position as far as the front end
of the balloon catheter 23 reaches the front end of the artificial
blood vessel A as shown in FIG. 27, whereupon the balloon 23b is
inflated by introducing air through the opening 23c as shown by
dash-and-dot lines in FIG. 27 thereby to restore the artificial
blood vessel A completely to its original shape and securely fix it
onto the inner wall of the blood vessel. At this time the thorns
stick into the inner wall of the blood vessel 9 and are embedded
therein. After the artificial blood vessel A has been thus fixed,
the balloon 23b of the balloon catheter 23 is deflated by drawing
air through the opening 23c and the balloon catheter 23 is pulled
out from the artificial blood vessel A by pulling the pipe 23a
rearwardly. Then it is confirmed that the artificial blood vessel A
has been fixed onto the inner wall of the blood vessel 9, and then
the wire 3 is pulled out of the tube 2. As the front end of the
wire 3 passes the rear edge of the side window 1 of the tube 2 as
shown in FIG. 8, the loop portion 4a of the string 4 that has been
caught by the wire 3 at the side window 1 is released from the wire
3. Under the condition, when the tube 2 is pulled out, the string 4
slips out of the loops 13 of the artificial blood vessel A. The
balloon catheter 23 and the tube 2 are then connected again by the
fastener 24 and pulled out of the human body with only the
artificial blood vessel A left at the desired position in the blood
vessel 9.
[0086] As mentioned above, in accordance with the invention, the
artificial blood vessel A is implanted into the affected portion
26, and restored to its original shape thereby to effectively
prevent occlusion of the affected portion 26 in the blood vessel 9.
With the above-mentioned collapsing method, the artificial blood
vessel A can be collapsed with ease and accuracy. It is difficult
to fold the front end wire ring 10.sub.1 into such a small shape
that can be contained in a catheter 8 merely by applying
non-directional external forces thereto. However, the dividing
points 41.sub.1, 43.sub.1 which equally divide the circumference of
the front wire ring 10.sub.1 are pulled forward and the midpoints
42.sub.1, 44.sub.1 between the dividing points 41.sub.1, 43.sub.1
are restrained from moving forward following the dividing points
41.sub.1, 43.sub.1 by a tapered surface 18d, so that the dividing
points 41.sub.1, 43.sub.1 form forwardly directed peaks and the
midpoints 42.sub.1, 44.sub.1 form the bottoms of forwardly directed
valleys with the midpoints 42.sub.1, 44.sub.1 serving as footholds,
so that the front end wire ring 10.sub.1 as a whole takes a regular
wavy shape. After the front end wire ring 10.sub.1 has been folded,
as the dividing points 41.sub.1, 43.sub.1 provided on the front end
wire ring 10.sub.2 are farther pulled forward by the front pull
string 20, the pulling force is transmitted to the points 41.sub.3,
43.sub.3 on the intermediate rings 12 corresponding to the dividing
points and the points 41.sub.2, 43.sub.2 on the rear end wire ring
10.sub.2 corresponding to the dividing points through the tensile
cover 7, and at the same time the points 42.sub.3, 44.sub.3 on the
intermediate rings 12 corresponding to the midpoints and the points
42.sub.2, 44.sub.2 on the rear end wire ring 10.sub.2 corresponding
to the midpoints are restrained by the tapered surface 18d, so that
the intermediate wire rings 12 and the rear end wire ring 10.sub.2
are also folded to take a wavy shape having the same phase as that
of the front end wire ring 10.sub.1, thereby to enable the
artificial blood vessel A to be collapsed into a small size with
ease.
[0087] What should especially be referred to is that the method of
collapsing the appliance to be implanted in accordance with the
invention is characterized by that the end wire rings 10.sub.1,
10.sub.2 provided at the opposite ends of the artificial blood
vessel A are connected by only a tubular cover 7 which is made of a
flexible and tensile sheet; and that the front end wire ring
10.sub.2 is pulled forward by means of the device B for
transporting artificial blood vessels. The conventional method, in
which the appliance to be implanted is pushed at the rear end so as
to be inserted into a human organ, requires a relatively strong
frame mainly of connecting wire rings in order to transmit the
force applied to the rear end portion of the appliance to the
forward portion thereof. However, the invention is based on the
idea of pulling the front end wire ring 10.sub.1 forward, thereby
to make insertion of the appliance easy even though no frame is
provided. In addition, the cover 7 is transformed into any desired
shape as the wire rings 10.sub.1, 12, 10.sub.2 are folded, thereby
to avoid the mutual interference of the cover 7 and the wire rings
10.sub.1, 12, 10.sub.2 which would otherwise occur if frames are
provided. Therefore, the method of collapsing the appliance in
accordance with this invention makes it possible to collapse the
whole artificial blood vessel A into a small size with ease by
folding each of the wire rings 10.sub.1, 12, 10.sub.2, into a wavy
shape.
[0088] In this embodiment, in order to collapse the appliance, the
loops 13 are formed at the dividing points 41.sub.1, 43.sub.1 of
the front end wire ring 10.sub.1 and the front pull string 20 is
passed through the loops 13 and pulled forward, thereby to make the
operation of collapsing the appliance very easy. In particular, the
pulling force can effectively be transformed to a collapsing force
because the dividing points 41.sub.1, 43.sub.1 are gathered to
approach each other by pulling the common front pull string 20
passed through the pair of loops 13, 13.
[0089] In this embodiment, the funneled tube 18 whose inner surface
is gradually reduced in diameter toward the front end thereof is
used to collapse the artificial blood vessel A. As the artificial
blood vessel A is inserted into the funneled tube 18 deeper, the
dividing points 41.sub.1, 43.sub.1 and the midpoints 42.sub.1,
44.sub.1 are gathered to approach each other, thereby to enable the
artificial blood vessel A as a whole to be collapsed into a small
size. In this embodiment, as resiliently deformable projections 18c
are formed on the tapered inner surface 18d of the funneled tube 18
so as to engage with the midpoints 42.sub.1, 44.sub.1, the
midpoints 42.sub.1, 44.sub.1 are pushed to approach each other by
the counterforce of the projections 13c. A space is formed between
the front end wire ring 10.sub.1 and the funneled tube 18 due to
the projections 18c, thereby effectively to prevent the artificial
blood vessel A from being securely caught in the funneled tube 18
due to the sliding resistance which would otherwise be increased if
the front end wire ring 10.sub.1 were in tight contact with the
funneled tube 18. The same is true with the intermediate wire rings
12 and the rear end wire ring 10.sub.2.
[0090] In this embodiment, the flexible braid members 10a are
circumferentially arranged on the end wire rings 10.sub.1, 10.sub.2
so as to prevent particularly the front end wire ring 10.sub.1 from
being damaged to cause the artificial blood vessel A to lose its
function. In particular, if the front end wire ring 10.sub.1 is
bent beyond its elastic limit, not only does it become difficult
for the ring to be restored to its original annular shape but also
it becomes impossible to move the ring in the catheter 8 because
the bent portion is caught in the catheter 8. However, as the braid
members 10a are provided, they diffuse the tension which would
otherwise be locally applied to the dividing points 41.sub.1,
43.sub.1 when the dividing points 41.sub.1, 43.sub.1 are strongly
pulled, thereby to prevent the dividing points from being bent
beyond the elastic limit of the ring 10.sub.1. Consequently, the
braid members 10a prevent plastic deformation of the front end wire
ring 10.sub.1, provide the ring with a proper capability of
restoring to the annular shape and of traveling smoothly in a
catheter, and enable the front end wire ring 10.sub.1 to be folded
into a regular wavy form.
[0091] The artificial blood vessel A constructed without a frame as
mentioned above properly functions for the intended purpose. The
artificial blood vessel A in accordance with the invention is so
constructed that the cover 7 itself is made of a tensile material
and is held by the intermediate wire rings 12 at appropriate points
thereof and that when the whole artificial blood vessel A is
released from the state of being collapsed and each of the wire
rings 10.sub.1, 10.sub.2, 12 is resiliently restored to the annular
shape, the cover 7 is restored to the original proper tubular shape
by the wire rings 10.sub.1, 10.sub.2, 12. The conventional
appliance having a frame, if put in a bent portion of a human
organ, is likely to be deformed flatly because of mutual
interference of the component parts. However, the artificial blood
vessel A having no frame in this embodiment can be transformed into
any desired shape so as to conform to different shapes of human
organs.
[0092] In this case, as the cover 7 is of a sheet woven with warps
and wefts, and the warps are made of mono-filament of polyester
(about 15 denier), whose stiffness helps keep the shape of the
cover 7, and the wefts are of multi-filament of polyester (about 50
denier), whose closeness gives the sheet waterproofness, the whole
cover 7 is flexible, resistive to axial tension, keeps its tubular
shape by itself, and can prevent leakage of blood.
[0093] As the sheet of the cover 7 is in the form of bellows, the
whole artificial blood vessel A is easily bendable so that the
condition of the artificial blood vessel A implanted into a human
organ is improved. As the restraining strings 14 bridge the end
wire rings 10.sub.1, 10.sub.2, the bellows can be prevented from
stretching beyond the limit to become flat.
[0094] In this embodiment, as the flexible braid members 10a are
circumferentially arranged on the end wire rings 10.sub.1, 10.sub.2
of the artificial blood vessel A, the inner wall of a human organ
can be prevented from being damaged by direct contact with the end
wire rings 10.sub.1, 10.sub.2 in addition to the advantage that the
front end wire ring 10.sub.1 can be prevented from being
plastically deformed when folded into a small size as mentioned
above. The braid members 10a also help seal both ends of the
implanted artificial blood vessel A tightly to the inner wall of a
human body, thereby to effectively prevent leakage of blood through
the ends of the artificial blood vessel A when implanted.
[0095] As the thorns 12a.sub.1 project from the intermediate wire
rings 12, they stick into the inner wall of a human organ to be
embedded therein so that the whole artificial blood vessel A is
fixed to the human organ. Therefore, after the artificial blood
vessel A has been implanted in the human organ, the thorns
12a.sub.1 effectively prevent displacement of the artificial blood
vessel A, which may cause the vessel A to be carried by blood flow
downstream in the blood vessel. As each of the thorns 12a.sub.1 is
formed by curving a wire into a loop, crossing both end portions of
the wire, and fixing the crossed parts with a string or the like,
the thorns 12a.sub.1 can be formed with ease and remain reliable in
use for a long time, even though the intermediate wire rings 12 are
made of a material which is difficult to weld.
[0096] On the other hand, by using the device C for introducing
artificial blood vessels in accordance with the invention, the
artificial blood vessel A can be smoothly introduced into the
catheter 8. In particular, the artificial blood vessel A is
inserted into the cartridge 6 by opening the check valve 55 as far
as the artificial blood vessel A reaches a position so that it is
completely contained therein. Before or after the above insertion,
the cartridge 6 is attached to the attachment 5 provided at the
open end 8a of the catheter 8, and then the artificial blood vessel
A is pulled forward farther so as to be introduced into the
catheter 8 through the attachment 5. In this case, when the check
valve 55 in the attachment 5 is opened, the check valve 65 of the
cartridge 6 is closed, so that blood flowing into the cartridge 6
is prevented from flowing outside the body through the cartridge 6
without fail. In addition, if the artificial blood vessel A is
inserted directly into the catheter 8, the artificial blood vessel
A cannot be inserted smoothly because the catheter 8 and the
artificial blood vessel A are flexible, and the catheter 8 is
likely to be bent by the force applied to the catheter 8 or the
artificial blood vessel A, thereby to block the path of the
artificial blood vessel A or to damage the catheter 8 itself.
However, in this embodiment, as the artificial blood vessel A is to
be inserted into the catheter 8 through the attachment 5 and the
cartridge 6, the attachment 5 and the cartridge 6 are made
relatively strong and easy to handle, so that the catheter 8 will
not be broken, thereby to enable the artificial blood vessel A to
be introduced into the catheter 8 smoothly with ease. In this case,
as the bore diameter di of the attachment 5 of the catheter 8 is
made bigger than the bore diameter d.sub.3 of the open end 8a of
the catheter 8 and the bore diameter d.sub.2 of the front end
portion of the cartridge 6 is smoothly connected to the bore
diameter d.sub.3 of the open end 8a of the catheter 8 when the
cartridge 6 is attached to the attachment 5, the artificial blood
vessel A can be prevented from being swollen in the attachment 5
and caught therein, so that the artificial blood vessel A can be
introduced directly deeper into the catheter 8.
[0097] The invention is not limited to the above-mentioned
embodiments. For example, in the above embodiment, the front end
wire ring 10.sub.1 has its circumference divided into two equal
arcs to set two dividing points 41.sub.1, 43.sub.1 and the two
midpoints 42.sub.1, 44.sub.1. As shown in FIG. 28, four dividing
points 141.sub.1, 143.sub.1, 145.sub.1, 147.sub.1 and four
midpoints 142.sub.1, 144.sub.1, 146.sub.1, 148.sub.1 may be set by
quadrisecting a front end wire ring 110.sub.1. As shown in FIG. 29,
three dividing points 241.sub.1, 243.sub.1, 245.sub.1 and three
midpoints 242.sub.1, 244.sub.1, 246.sub.1 may be set by trisecting
a front end wire ring 210.sub.1.
[0098] In the above embodiment, the device B for transporting
artificial blood vessels is provided with a pair of strings 4 with
loop portions 4a. The strings 4 need not always be provided in a
pair. However, the strings provided in a pair are effective because
a balanced pulling force can be applied to the artificial blood
vessel A. The loop portions 4a may be twisted as a whole.
[0099] As the balloon catheter 23 is used in the above embodiment,
the device B for transporting artificial blood vessels is
incorporated into the balloon catheter 23. If the balloon catheter
23 is unnecessary, the artificial blood vessel A may be introduced
into or taken out of the catheter by directly operating the tube 2
of the device B for transporting artificial blood vessels.
[0100] The following method of supporting restoration of the
appliance to be implanted is effectively used in the above
embodiment. The method is to enable the artificial blood vessel A
as the appliance to be implanted to be pulled rearward at the rear
end wire ring 10.sub.2 through the rear loops 13a formed on the
rear end wire ring 10.sub.2 of the artificial blood vessel A at the
points 42.sub.2, 44.sub.2 corresponding to the midpoints as shown
in FIG. 30. In particular, in the above embodiment, for example,
the artificial blood vessel A may be mistakenly released at a
position off the affected portion 26 shown in FIG. 26. In such a
case, when the artificial blood vessel A is pulled backward by
operating the device B for transporting artificial blood vessels,
the front end wire ring 10.sub.1 only moves toward the rear end
wire ring 10.sub.2, so that the artificial blood vessel A shrinks
in the axial direction thereof and may not be restored to a proper
shape. In case the balloon catheter 23 is inserted into the
artificial blood vessel A which has been released at a constricted
part, the balloon catheter 23 may not be inserted with accuracy
into the opening of the rear end wire ring 10.sub.2 of the
artificial blood vessel A but be caught by the peripheral edge of
the opening, and the rear end wire wing 10.sub.2 is pushed toward
the front end wire ring 10.sub.1 and shrinks in the axial direction
thereof, so that the artificial blood vessel A may not be restored
to a proper shape. Once this happens, the above-mentioned device B
for transporting artificial blood vessels can no longer be an
effective means for correcting the shrinkage of the artificial
blood vessel A or pulling it back to where it should have been
released, as it has a function of only pulling the front end wire
ring forward.
[0101] In such a case, it is effective to use both a method of and
a device for pulling the artificial blood vessel A back to the
proper position after it has been released.
[0102] FIGS. 30 and 31 show a device D for helping restoration for
the above purpose, which comprises a pair of tubes 102 each of
which is provided with a side window 101 near its front end, and a
pair of wires 103 each of which is inserted into one of the tubes
102. Rear loops 13a are formed at the points 42.sub.2, 44.sub.2 on
the rear end wire ring 10.sub.2 corresponding to the midpoints, and
the rear loops 13a are directly hooked by the wires 103 which have
been pulled out of the tubes 102 through the side window 101, and
the rear loops 13a are held by the wires 103 by inserting the wires
103 into the tubes 102 again. Then the tubes 102 each of which
contains the wire 103 are introduced into the catheter 8 together
with the artificial blood vessel A. In particular, a bore 23d
oblong in transverse section is formed in the wall of the pipe 23a
of the balloon catheter 23 used in the above embodiment to extend
along the length of the pipe from the rear end thereof to near the
balloon 23b as shown in FIG. 32. An open window 23d.sub.1 is formed
at the rear end of the bore 23d, into which a pair of tubes 102 are
introduced through the window 23d.sub.1 and drawn out through an
open window 23d.sub.2 formed at the forward end of the bore 23d.
The tubes 102 can be moved together with the balloon catheter 23
longitudinally when the balloon catheter 23 is pulled forward, and
they can also be moved relative to the balloon catheter 23
longitudinally when the tubes 102 alone are operated. The device D
for helping restoration is used when the position of the artificial
blood vessel A is to be adjusted after it has been released as
shown in FIG. 26, or when the balloon catheter 23 is inserted into
the artificial blood vessel A as shown in FIGS. 26 and 27. When the
artificial blood vessel A has been released at a position a little
ahead of the affected portion 26 as shown in FIG. 26, the tubes 102
containing the wire 103 is pulled rearward to pull back the rear
end wire ring 10.sub.2 thereby to cause the front end wire ring
10.sub.1 to follow the rear end wire ring 10.sub.2. When the
balloon catheter 23 is inserted as shown in FIGS. 26 and 27, the
tubes 102 containing the wires 103 are pulled back to hold the rear
end wire ring 10.sub.2 not to move forward, and the balloon
catheter 23 is pushed into the artificial blood vessel A Then, only
the wires 103 which are contained in the tubes 102 are pulled
rearward as far as the front end of the wires 103 reaches the side
window 101 of the tubes 102, whereupon the rear loops 13a of the
artificial blood vessel A are released from the wires 103, so that
the artificial blood vessel A is detached from the device D for
helping restoration. As a result, the device D for helping
restoration as well as the balloon catheter 23 can be withdrawn
with only the artificial blood vessel A left in the affected
portion 26.
[0103] By using these devices jointly, a proper distance between
the front end wire ring 10.sub.1 and the rear end wire ring
10.sub.2 can always be maintained. Therefore, it is possible to
prevent the artificial blood vessel A from being shrunk
longitudinally to deform its proper shape, and to complete
insertion of the balloon catheter 23 and adjustment of the position
of the artificial blood vessel A quickly and accurately.
[0104] The device for helping restoration of the appliance to be
implanted can be of a construction shown in FIG. 33. The device is
provided near the side window 101 of the tube 102 with a pair of
strings 104 each of which has its front end portion formed into a
loop. The loop portion of each string 104 is passed through a pair
of rear loops 13a and hooked by the wire 103 like the device B for
transporting artificial blood vessels. The tube 102 also is
contained in the pipe 24a of the balloon catheter 23 and
transported like the above-mentioned tube 102.
[0105] In the above-mentioned embodiments, in some cases the
balloon catheter 23 is not used. In such cases the tube 102 is to
be detachably connected with the device for transporting the
artificial blood vessel so that the tube and the device can be
transported as a unit.
[0106] The appliance according to the present invention, especially
when used as an artificial blood vessel, has various effects or
advantages such that (1) the appliance has improved liquid
proofness and positional stability or fixedness at the position
where it has been implanted, and (2) that it has improved implanted
condition with resulting reduction of adverse influences otherwise
caused by implantation of such artificial appliances in a human
body. Reasons for the improvement of the liquid proofness and
fixedness will be explained with reference to FIGS. 34 and 35.
[0107] When the artificial blood vessel has been released in a
blood vessel adjacent to an affected portion thereof where an
aortic aneurysm exists, the wire rings p1 arranged outside the
cover p2 are brought into direct contact with the inner wall
surface p3 of the blood vessel due to its own restoring force
without the cover p2 intervening. On the contrary, if the wire
rings were arranged inside the cover q2 as shown at q1 in FIG. 35,
the cover would intervene between the wire rings q1 and the inner
wall surface q3 of the blood vessel to effect an indirect surface
contact therebetween, with the resilient restoring force of the
rings q1 being dissipated by the intervening cover.
[0108] In FIG. 34 the wire rings p1 of the artificial blood vessel
of the present invention directly contact the inner wall surface p3
of the blood vessel without the cover p2 intervening, thereby to
effect a linear contact rather than a surface contact therebetween,
so that the wire rings p1 exercise a pressing force onto localized
areas on the inner wall surface p3 of the blood vessel. This
effects a good sealed condition between the wire rings and the
inner wall of the blood vessel.
[0109] Since the wire rings p1 are arranged outside the cover p2,
the blood p flowing through the cover p2 exerts a fluid pressure as
shown at p5 from inside the cover to expand it, and the expanding
force of the cover is likely to be concentrated on the wire rings
p1 to expand them radially outwardly, so that the expanding force
added to the resilient restoring force of the wire rings increases
the sealing effect between the implanted artificial blood vessel
and the inner wall surface p3 of the blood vessel. In FIG. 35, the
pressure q5 of the blood q4 flowing through the cover q2 acts on
the cover q2 from inside it but scarcely acts on the wire rings q1
to expand them radially outwardly, so that the sealing effect of
the wire rings q1 on the inner wall surface q3 of the blood vessel
is scarcely increased.
[0110] The artificial blood vessel of the present invention is able
to provide an effective seal at the wire rings contacting the inner
wall of the blood vessel thereby to prevent leakage of blood
through a gap therebetween, to provide an improved liquid tightness
between the implanted artificial blood vessel and the adjacent
portions of the blood vessel thereby to prevent leaking blood, if
any, from reaching the affected part of the blood vessel such as an
aortic aneurysm, and to provide improved positional stability of
the implanted artificial blood vessel by effectively preventing the
wire rings from slipping on the inner wall of the blood vessel and
consequently the whole of the implanted artificial blood vessel
from being displaced or moved away from the position where it must
stay.
[0111] The above effects are marked especially where the
intermediate wire rings contact the inner wall surface of the blood
vessel. Unlike the end wire rings, the intermediate wire rings are
fixed to the cover at positions other than the opposite ends of the
cover, so that the expanding force of the cover caused by the blood
pressure inside it acts as a whole to uniformly expand the
intermediate wire rings radially outwardly, and the total force
acting on the intermediate wire rings is greater than that acting
on the opposite end wire rings. Therefore, even if blood should
enter the space between the end wire rings and the inner wall
surface of the blood vessel, the intermediate wire rings contact
the inner wall surface of the blood vessel at a greater pressure
and more tightly than the end wires so as to efficiently prevent
the entering blood from reaching the aneurysm. Thus, the invention
provides a double or multiple-stage sealing system.
[0112] In one conventional type of artificial blood vessel (not
shown) in which the opposite end wire rings are connected by an
elastic wire framework, the support rod exerts a force on the wire
rings to prevent the resilient restoration thereof, so that the
artificial blood vessel has a lower adhesiveness and positional
stability of the wire rings to the inner wall of the blood vessel
than in the prevent invention (which is free of an elastic wire
framework extending between and connecting the end wire rings) and
it is difficult to prevent leakage of blood without fail.
[0113] Reasons for the improved condition of the implanted blood
vessel and reduction of adverse influences caused by the
implantation of the artificial blood vessel of the present
invention will now be described.
[0114] The human body has a characteristic such that when a foreign
body enters a blood vessel, the intima of the blood vessel covers
or envelopes the foreign body to assimilate it. In particular, when
an artificial blood vessel has been implanted in a blood vessel to
be treated, the intima of the blood vessel expands over the inner
wall surface of the implanted artificial blood vessel to cover and
assimilate it. In the arrangement of FIG. 35, in which the wire
rings are disposed inside the cover, the projections provided by
the rings q1 on the inner surface of the cover q2 become an
obstacle to smooth, uniform expansion of the intima from the
adjoining blood vessel. In other words, the expansion of the intima
is likely to be impeded by the projections and it takes a
considerably long time for the intima to uniformly cover the
implanted artificial blood vessel, in which a thrombus is likely to
be formed in the course of expansion of the intima. As the thrombus
grows, the blood vessel becomes constricted, and there is danger of
the thrombus coming off to be carried over to a capillary vessel
and cause necrosis in the adjacent cells.
[0115] In accordance with the present invention, the wire rings p1
are provided outside the cover p2, the inner surface of which is
continuously smooth from one end thereof to the other, so that the
intima of the blood vessel will expand over the inner surface of
the cover of the implanted artificial blood vessel smoothly and at
an efficient speed. This means that the implanted artificial blood
vessel is easily assimilated into the tissue of the inner wall of
the blood vessel, with resulting reduction of the danger of a
thrombus being formed to cause serious damage, such as necrosis,
and realization of a long, stable fixed condition of the implanted
artificial blood vessel.
[0116] In the previously described conventional type of artificial
blood vessel including an elastic wire framework inside the cover,
the framework impedes expansion of the intima as in the arrangement
of FIG. 35 so that no such effects or advantages as in the present
invention can be expected.
[0117] In accordance with the invention, if the inner pressure of
the cover of the implanted artificial blood vessel should increase
to an abnormally high level, the wire rings provided outside the
cover can effectively prevent occurrence of serious situations such
as rupture of the cover to cause profuse bleeding.
[0118] Further advantages provided by preferred features of the
invention are described below.
[0119] Relatively hard, stiff thread must be used to form an
artificial blood vessel as a concrete, solid structure if it is not
to be supported by an elastic wire frame. If such stiff thread were
used in the whole of the cover of the artificial blood vessel,
however, the cover would become too bulky and stiff to be smoothly
introduced into a blood vessel.
[0120] In accordance with the invention, the warps with which the
cover is woven are preferably made of mono-filament so as to keep
the cover sufficiently rigid as a structure and make it possible to
fold the artificial blood vessel into a less bulky size than
otherwise. Since the artificial blood vessel of this type is
usually introduced into a relatively thin blood vessel such as the
femoral blood vessels, the fact that the artificial blood vessel of
the present invention can be folded into a small size is an
important factor to enable successful implantation of the
artificial blood vessel. In addition, since the wefts of the cover
are preferably made of multifilament, when the intima of the blood
vessel expands over the implanted artificial blood vessel to
assimilate it, the intima is likely to enter the spaces among the
filament fibers to effect a stable fixed state of the implanted
artificial blood vessel. Due to entanglement of the fibers of the
wefts the cover is finely meshed and highly liquid proof.
[0121] When an artificial blood vessel is to be implanted in a
curved portion of a blood vessel, that portion of the wall of the
artificial blood vessel which is to lie along the outer lateral
side of the wall of the curved blood vessel, which has a relatively
large radius of curvature, must be stretched or lengthened while
the opposite side portion of the wall of the artificial blood
vessel which is to lie along the opposite inner lateral side of the
wall of the curved blood vessel, which has a relatively small
radius of curvature, must be shrunk or shortened so that the
implanted artificial blood vessel may be properly positioned with
the openings of the opposite end wire rings being held
perpendicularly to the wall of the blood vessel. This is readily
achieved in accordance with the present invention by forming the
cover of the artificial blood vessel as a bellows. With implanted
artificial blood vessels not formed into bellows, it is difficult
for the implanted artificial blood vessel to be transformed in such
a manner and to be brought into close contact with the wall of the
blood vessel particularly at that portion thereof which has a
relatively small radius of curvature.
[0122] This is particularly true with that type of artificial blood
vessel which contains a wire frame, which is highly resistive to
curving or transformation of the artificial blood vessel and
consequently makes it extremely difficult to effect proper
implantation thereof. Moreover, there is a danger of the opposite
ends of the frame sticking into the wall of the blood vessel to
break it. With the conventional type of artificial blood vessel
with a wire framework or without bellows it is quite difficult to
accomplish a proper implanted condition, and leakage is likely to
occur between the blood vessel and the implanted artificial blood
vessel in loose contact therewith. Due to the loose contact or low
positional stability the implanted artificial blood vessel is
likely to be pushed away by the blood flow.
[0123] The artificial blood vessel of the invention, having the
cover formed into bellows, can easily conform to the curvature of
the blood vessel in which it is to be implanted so as to be kept in
close contact therewith at a fixed condition. In addition, due to
the bellows, it is possible to change the axial length of the
artificial blood vessel within a certain range, so that after the
artificial blood vessel has been implanted, it may be axially
adjusted so as to accomplish the most appropriate implanted
condition. Due to the bellows, it is also possible to lengthen or
shorten the artificial blood vessel so that it can be reduced in
size for easier introduction into a catheter.
[0124] The above is not possible with the conventional type of
artificial blood vessel, in which the wire frame connecting the
opposite end rings is detrimental to transformation of the
artificial blood vessel.
[0125] In the artificial blood vessel of the present invention, all
the wire rings, including the end wire rings, are arranged outside
the cover. There is a risk that the exposed end wire rings may
pierce the wall of the blood vessel to cause bleeding. To minimize
this risk, in accordance with a preferred aspect of the invention,
a protective material covering the end rings functions as a buffer
against the inner wall of the blood vessel.
[0126] The thorns of the inventive artificial blood vessel
preferably project from the circumference of at least one of the
wire rings. Since the wire rings are outside the cover, there is no
danger of the thorns piercing the cover, so that it is possible to
fix the artificial blood vessel onto the inner wall of a blood
vessel with good liquid proofness and positional stability.
[0127] Since the artificial blood vessel of the present invention
has no supporting frame or rod, the provision of the rear pull
means (see, e.g., rear loops 13a in FIG. 30) makes it possible to
freely adjust the length of the artificial blood vessel after it
has been released from the catheter at a position in a blood vessel
where it is to be implanted. A blood vessel has branches such as
the aortic arch having the brachiocephalic trunk branching
therefrom, and the artificial blood vessel must be positioned
accurately at the required position so as not to block those
branches which are not to be blocked. Erroneous blocking of such
branches is likely to result in a critical damage. With the rear
pull means accurate positioning of the artificial blood vessel is
facilitated.
[0128] FIG. 36 shows a modified embodiment of the invention, in
which the end wire rings W1 comprise a plurality, e.g., four, wire
elements W2 bound together, and in a similar manner the
intermediate wire rings W3 comprise a plurality, e.g., four,
elements W4 bound together. The wire elements W2 and W4 are
preferably made of nickel-titanium alloy. With the arrangement, the
wire rings W1 and W3 have both sufficient flexibility and strength
so that there is little danger of the wire rings injuring the blood
vessel, and they are able to move in response to the pulsation of
the blood vessel, and endure the repeated load caused thereby, for
a long time. Should any of the wire elements be broken, the rings
would not immediately do harm to the human body.
[0129] As the wire rings comprise a bundle of wire elements, they
are more flexible than a wire ring which comprises a single wire
element having a high strength. The rings can softly contact the
inner wall of the blood vessel while maintaining a sufficient
strength. Rigid wire rings might stick the inner wall of a human
blood vessel and break it. Since the wire rings of the artificial
blood vessel of the present invention are flexible, there is less
danger of the wire rings breaking the wall of the blood vessel, and
the flexibility of the material enables proper restoration of the
folded wire rings. Since the human blood vessel pulsates, the
implanted artificial blood vessel receives from the pulsating blood
vessel a repeated load for a long time. The wire rings of the
invention made of a plurality of wire elements are flexible so as
to move in response to the pulsation and more resistive to the
repeated load than if they were made of a single strong wire
element. Breakage of one of the wire elements does not result in
immediate failure of the whole wire ring and consequently the
implanted artificial blood vessel.
[0130] FIG. 38 shows a modified embodiment of the invention, in
which each of the intermediate wire rings 1012 is provided with a
pair of thorns 1010 shaped like a Japanese Katakana letter "" (a
squared U-shape) in transverse section. The thorns 1010 are fixed
at the diametrically opposite positions of the wire ring 1012 by
means of a thread 1011 so as to be directed radially outwardly.
Since the intermediate wire rings 1012 are provided outside the
cover 1013, the thorns thereon do not pierce the cover, so that the
artificial blood vessel may be kept liquid tight. In FIG. 39 the
thorns 1020 are L-shaped in transverse section and fixed to the
intermediate wire ring 1022 by means of a thread 1021, similar to
the thorns 1010 in FIG. 38.
[0131] Since all the wire rings are arranged outside the cover, the
thorns are provided on the rings without piercing the sheet of the
cover. Thus, the artificial blood vessel can be fixed at a required
position in a blood vessel without influencing the liquid tightness
of the implanted artificial blood vessel.
[0132] Nickel-titanium alloy is highly flexible and resilient. With
the wire rings of the invention made of this alloy the artificial
blood vessel can be folded into a small size when it is inserted
into a catheter and restored to its original size without fail when
it is released at the target position. Even if the implanted
artificial blood vessel receives a pulsating load caused by the
pulsation of the blood vessel via its wall for a long time, the
flexible, resilient nickel-titanium alloy enables the wire rings to
move in response to the pulsation without causing damage to the
implanted artificial blood vessel. The end wire rings which
comprise a bundle of wire elements made of nickel-titanium alloy
have increased strength and flexibility and reduced probability of
being broken. The manners in which the thorns are formed and fixed
to the wire rings, as shown in FIGS. 38 and 39 and described above,
are effective especially when the wire rings are made of
nickel-titanium alloy which is hard to weld.
[0133] FIG. 37 schematically shows the material or sheet of an
artificial blood vessel cover 1001 expanded and enlarged. The sheet
is woven with warps of monofilament 1002 and wefts of
multi-filament 1003. In particular, the mono-filament 1002 may
comprise about 12- denier thick polyester fiber. The multi-filament
1003 comprises a twist of an about 52-denier bundle of ultra fine
micro fibers 1003a of polyester and an about 10-denier reinforcing
thread 1003b of Vectran (a trade name of thermotropic liquid
crystal). The resulting cover of the artificial blood vessel has a
combined strength of the mono-filament 1002 and the reinforcing
thread 1003b and the flexibility, liquid proofness and fixability
to the inner wall of the blood vessel of the ultra fine micro
fibers 1003a of the multi-filament 1003. Since the artificial blood
vessel must endure a high blood pressure for as long a time as
decades of years, it is essential that it should have a sufficient
strength in the radial direction. The above-mentioned Vectran
provides not only as high a strength as the conventional artificial
blood vessel used in the surgical replacement of blood vessels, but
also a flexibility to enable easy folding of the artificial blood
vessel of the invention.
[0134] Possible Applications in Industry
[0135] As mentioned above, the method of collapsing the appliance
to be implanted in accordance with the invention is useful to fold
the wire rings, which are components of the appliance, into small,
regular wavy shapes of the same phase, thereby to collapse the
appliance into a small size. The appliance to be implanted in
accordance with the invention can be implanted into a target
position without fail and has an appropriate construction so as not
to hinder the operation of collapsing. The device for introducing
the appliance to be implanted into the catheter is useful to
introduce the appliance into the catheter without bleeding.
* * * * *