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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a balloon catheter. More particularly, it relates
to a balloon catheter for expanding and thereby remedying stenosis in a
blood vessel for improving the state of the distal side blood stream.
2. Description of the Prior Art
In the event of stenosis or obturations in the vascular system, such as
blood vessels, percutaneous transuminal angioplasty (PTA) or percutaneous
transluminal coronary angioplasty (PTCA) is performed for enlarging or
recanalizing the narrowed or obturated site of the vascular system to
thereby improve the body liquid stream towards the distal side of the
vascular system. In PTA or PTCA, after a blood vessel is procured
percutaneously, a fine guide wire is passed through the vessel. A catheter
having an end balloon (expandable member) is introduced into the vessel,
using this guide wire as the guide, until the balloon is positioned at the
site of lesion where stenosis or obturation has occurred. A liquid such as
contrast medium is injected continuously into the balloon via an end hub
under a pressure of several to ten atmospheres for dilating the balloon
towards the inner wall of the blood vessel for pressuring and thereby
enlarging the narrowed or obturated sites.
As a balloon catheter employed in PTA or PTCA, there is known a balloon
catheter having a coaxial dual tube system including an inner tube opened
at one end and defining a first lumen and an outer tube surrounding the
inner tube, forming a second lumen with the inner tube and provided with a
distal balloon, or one in which a tubular member defining a lumen is
provided with a distal balloon surrounding the end of the tubular member.
In the case of the former balloon catheter having the coaxial dual tube
system, ring markers formed of an X-ray opaque material are provided at
predetermined portions of the inner tube in the balloon that are
substantially in register with both ends of the balloon., these ring
markers being used as means for identifying the cylindrical portion of the
balloon under X-ray fluoroscopy. However, considering that the balloon
catheter is caused to proceed through the inside of the blood vessel
presenting acute bend or bends, the risk is high that the inner tube
disposed within the balloon at the bends of the blood vessel be broken and
collapsed the lumen opened at one end the lumen opened at one end to
obstruct smooth progress of the guide wire.
For overcoming the above difficulties, there is also known a balloon
catheter in which a piping having at both ends thereof prescribed portions
substantially in register with both ends of the cylindrical portion of the
balloon is provided on the inner tube disposed within the balloon. While
it is possible with this known balloon catheter to prevent the inner tube
from being broken and collapsed, it is difficult for the balloon catheter
to proceed through the inside of the blood vessel presenting acute bend or
bends. Even supposing that the balloon catheter should have succeeded in
proceeding beyond the bend, the risk is high that the piping remains bent
to obstruct the progress thereof the blood vessel beyond the bend towards
the distal side of the vascular system.
OBJECT AND SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide a balloon
catheter which is free from the above problems of the prior art and which
is able to prevent breaking of the inner tube and obstructing of the lumen
in blood vessels presenting an acute bend or bends.
According to the present invention, there is provided a balloon catheter
comprising a tubular body including at least one lumen, and a foldable
balloon provided at a predetermined forward portion on the outer surface
of said tubular body so that the balloon communicates with at least one
lumen in said tubular body, wherein the improvement resides in that a
reinforcement is provided at a predetermined portion on the outer surface
of said tubular body surrounded by said balloon
According to the present invention, the diameter of a portion of the
balloon catheter which is introduced into the patient's body and which is
formed by said tubular body and the folded balloon is not more than 2.7
mm.
It is preferred that the reinforcement be formed of an X-ray opaque
material.
It is preferred that the X-ray opaque material be platinum, gold, tungstene
or alloys thereof.
It is preferred that the opaque material be a silverpalladium alloy.
It is preferred that the reinforcement be a wire in the form of a coil and
having a circular, rectangular or an elliptical cross-section.
It is also preferred that the wire of the coil is formed by a coil spring
having turns thereof in intimate and tight contact with one another.
Alternatively, turns of the coil spring may be arranged thick in both end
parts and thin in the intemediate part of the coil spring.
According to the present invention, the portions of the balloon catheter
surrounded by the balloon may be prevented from being broken and
collapsed, even when the catheter is proceeding through the inside of the
blood vessel presenting acute bend or bends, so that the balloon catheter
can be prceeded positively to the site of lesion in the blood vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described with reference to the
accompanying drawings in which
FIG. 1 is an enlarged sectional view showing the distal end part of the
balloon catheter according to a preferred embodiment of the present
invention,
FIG. 2 is a sectional view taken along line II--II of FIG. 1,
FIG. 3 is a sectional view taken along line III--III of FIG. 1,
FIG. 4 is a diagrammatic view showing the proximal end part of the balloon
catheter shown in FIG. 1,
FIG. 5 is an overall side view showing the balloon catheter of FIG. 1, with
a portion thereof being broken away,
FIGS. 6 to 10 are diagrammatic views for illustrating the operation of the
balloon catheter shown in FIG. 1,
FIGS. 11 and 12 are enlarged sectional views showing the distal end part of
balloon catheters according to modified embodiments of the present
invention; and
FIG. 13 shows a modification of the embodiment of FIG. 1.
DESCRIPTION OF PREFERRED EMBODIMENTS
By referring to the accompanying drawings, certain preferred embodiments of
a balloon catheter of the present invention including a tubular member
having two lumens will be explained hereinbelow in detail.
FIGS. 1 to 4 illustrate a preferred embodiment of the balloon catheter
according to the present invention. FIG. 1 is an enlarged sectional view
showing the distal side of the balloon catheter. FIGS. 2 and 3 are
sectional views taken along line II--II and line III--III of FIG. 1,
respectively. FIG. 4 is an enlarged sectional view showing the proximal
side of the balloon catheter.
As shown in FIGS. 1 to 4, the balloon catheter 10 of the present invention
includes an inner tube 1 having a first lumen opened at one end, an outer
tube 2 provided for encircling the inner tube 1 at a position set back a
predetermined distance from a foremost part 1a of the inner tube 1 and
defining a second lumen 6 between it and the outer surface of the inner
tube 1, and a balloon 3 including a distal end 7 attached to the inner
tube 1 and a proximal end 8 attached to the outer tube 2. The balloon 3
communicates with the second lumen in the vicinity of the proximal end 8.
and has a cylindrical section 3a, can be including at least a portion
thereof substantially cylindrical in contour to permit a constricted site
of the blood vessel to be dilated easily. A reinforcement 9 is wound about
a portion on the outer peripheral surface of the inner tube which is
substantially in register with the cylindrical section 3a.
The balloon catheter 10 has the inner tube 1 and the outer tube 2 as a
cathether tube or tubular body or member 5, the proximal end of which is
provided with a bifurcated branched hub 20, as shown in FIG. 4. The
branched hub 20 has a guide wire port 12 and an injection port 13
communicating with the first lumen 4 and with the second lumen 6,
respectively.
The first lumen 4 formed by the inner tube 1 plays the role of a guide wire
passage and a blood route or channel during use of the balloon catheter.
The first lumen communicates at its proximal end with the guide wire port
12 formed in the branched hub 20, such that a guide wire 15 for the
balloon catheter as later described is introduced into an opening end of
the guide wire port 12 so as to be guided into the first lumen 4.
The inner tube 1 is preferably formed of a material exhibiting certain
flexibility, including polyolefins, such as polyethylene, polypropylene,
ethylene-propylene copolymers or ethylene-vinyl acetate copolymers,
thermoplastic resins, such as polyvinyl chloride, polyamide elastomers or
polyurethane, silicone rubber or latex rubber. More preferred are the
aforementioned thermoplastic resins and most preferred are polyolefins.
The outer tube 2, in the inside of which the inner tube 1 is introduced, is
preferably mounted coaxially with the inner tube 1 and at a position in
which the foremost part of the outer tube is set back a small distance
from the foremost part 1a of the inner tube 1. The second lumen 6 is
defined between the inner surface of the outer tube 2 and the outer
surface of the inner tube 1. The second lumen 6 plays the role of a
channel for injection of, for example, contrast medium and dischaging of
residual air and communicates at its proximal end with the injection port
13 of the branched hub 20. The second lumen 6 also communicates at its
distal end with the inside of the balloon 3 at its rear end. The contrast
medium, for example, are injected and charged into the internal space of
the balloon 3 via the opening end of the injection port 13 and the second
lumen 6 while the residual air is discharged simultaneously.
The outer tube 2 is preferably formed of a material exhibiting certain
fexibility, including polyolefins, such as polyethylene, polypropylene,
ethylene-propylene copolymers or ethylene-vinyl acetate copolymers,
thermoplastic resins, such as polyvinyl chloride, polyamide elastomers or
polyurethane, silicone rubber or latex rubber. More preferred are the
aforementioned thermoplastic resins and most preferred are polyolefins.
The balloon 3 has its foremost part 7 and rear end 8 secured to the outer
peripheral surface of the foremost part of the inner tube 1 and to the
outer peripheral surface of the foremost part of the outer tube 2
liquidtightly, respectively, as with an adhesive or by heat fusion, for
delimiting an expansion space 14 between the inner surface of the balloon
3 and the outer surface of the inner tube 1. This expansion space 14
communicates at its rear end with the second lumen 6 along its overall
periphery so that the contrast medium, for example, may be charged into
the space 14 via the second lumen 6, as described hereinabove.
The balloon 3 may be folded in such a manner that, when the balloon is not
dilated, it may be folded and wrapped about the outer periphery of the
inner tube 1. In order that the constricted site of the blood vessel may
be dilated more easily, at least a portion of the balloon 3 is formed as a
substantially equidiametral cylinder for defining the aforementioned
cylindrical section 3a. The cylindrical section need not be a true
cylinder but may be in the form of a prism having a polygonal
cross-section.
It should be noted that the balloon 3 is tapered from the forward side of
the cylindrical section 3a to the foremost part 7 where it is secured to
the inner tube 1 and from the rear side of the cylindrical section 3a to
the rear end 8 where it is secured to the outer tube 2.
It should also be noted that, in the state in which the balloon 3 is folded
and wrapped about the inner tube 1, that is, the balloon 3 is wrapped
around the catheter tube 5, the portion of the balloon catheter introduced
into the patient's body be of an outside diameter of not more than 2.7 mm
at the maximum, since the balloon catheter can be used satisfactorily in
such case in the body cavity, above all, in a finer vasculum.
The balloon 3 is preferably formed of a material exhibiting certain
flexibility, including polyolefins, such as polyethylene, polypropylene,
ethylene-propylene copolymers, ethylene-vinyl acetate copolymers or
crosslinked ethylene-vinyl acetate copolymer, thermoplastic resins, such
as polyvinyl chloride, polyamide elastomers or polyurethane, silicone
rubber or latex rubber. More preferred are the aforementioned
thermoplastic resins and most preferred are the cross-linked ethlene-vinyl
acetate copolymers.
According to the present invention, a reinforcement 9 is wound about a
predetermined portion of the outer surface of the inner tube 1 which is
enclosed within the balloon 3, preferably the portion thereof in register
with the aforementioned cylindrical section 3a. With the reinforcement 9
thus wound about the inner tube 1, the inner tube is rendered more
resistant against buckling, so that there is no risk that the inner tube 1
disposed in the balloon 3 be broken or the first lumen 4 through which the
guide wire 15 for the balloon catheter is passed be broken even at a bend
of the blood vessel.
The reinforcement 9 is preferably formed of an X-ray opague material,
preferably platinum, gold, tungsten or alloys thereof and more preferably
a silver-palladium alloy, since a clear contrast image can then be
obtained under X-ray fluoroscopy and thus the cylindrical section 3a of
the balloon 3 can be identified more easily.
The reinforcement 9 is preferably a wire wound into a coil. By using the
coil as the reinforcement, the inner tube 1 can be reinforced more
strongly against buckling.
The wire of the coil preferably has a circular, rectangular or an
elliptical cross-section for inceasing reinforcing effects.
The wire in the form of a coil may preferably be a spring coil so wound
that its turns are in intimate contact with one another. With this dense
winding of the wire, the inner tube can be reinforced more strongly
against buckling.
The branched hub 20 is formed by an inner tube hub 22 and an outer tube hub
23. The inner tube hub 22 communicates with the first lumen 4, has a guide
wire port 12 through which the guide wire 15 for the balloon catheter is
introduced, and is secured to the inner tube 1. The outer tube hub 23
communicates with the second lumen 6, has an injection port 13 for
injecting contrast medium, for example, and is secured to the outer tube
2.
The outer tube hub 23 and the inner tube hub 22 are secured to each other.
The branched hub 20 is preferably formed of thermoplastic resins, such as,
for example, polycarbonate, polyamide, polysulfone, polyallylate or
methacrylatebutylene-stylene copolymers.
For explaining the operation of the balloon catheter of the present
invention shown in FIGS. 1 to 4, the method of using the balloon catheter
in angioplasty (PTA or PCTA) will be explained by referring to FIGS. 5 to
10.
It is preferred that, before conducting to angioplasty by dilating and
remedying constrictions occurred in the blood vessel, as much air as
possible be removed from the inside of the balloon catheter. To this end,
suction and injection means, such as a in-deflator, filled with contrast
mediaum is attached to the injection port 13 of the catheter and the
operation of alternate injection and suction is repeatedly performed to
remove the air in the second lumen 6 and the balloon 3 to replace it with
the contrast medium.
When the expansion space 14 of the balloon 3 and a space of the second
lumen 6 is filled with the contrast medium and the residual air is removed
completely, a predetermined amount of the contrast medium filled in the
expansion space 14 is sucked and discharged by an injector fitted with a
pressure gauge 24 to cause the balloon 3 to be wound about the inner tube
1 of the tubular member 5 to reduce the outside diameter of the balloon 3
so that the outside diameter of the portion of the balloon catheter 10
introduced into the patient's body is not more than 2.7 mm, in order to
make ready for insertion of the balloon catheter into the blood vessel in
angioplasty.
For angioplasty, a blood vessel 30 is procured, that is, peirced with the
dilater and sheath 25 as shown in FIG. 6(by relying upon, for example, the
Sheath method. A guiding catheter indwelled gauide wire is prepared. A
guiding catheter 26 is introduced into the blood vessel 30 along the guide
wire and left at an inlet 31 to the coronary artery having a target
lesion. The guide wire for the guide catheter is then removed.
The balloon catheter guide wire 15 is then introduced at the guide wire
port 12 of the balloon catheter 10 into the inner tube 1 of the tubular
member 5, that is, into the first lumen 4, until the guide wire is
protruded several centimeters beyond the end opening 1a of the inner tube
1, as indicated in FIG. 5. The resulting assembly is then introduced into
the guiding catheter 26 via a balloon catheter port 28 of a Y-shaped
connector 27, to the proximal end of which the guiding catheter 26 is
connected, as shown in FIG. 6. The balloon catheter 10 is then proceeded
through the inside of the guiding catheter 26 so as to be proceeded via
the forward end of the guiding catheter 26 into the blood vessel 30 having
the target lesion 30.
The balloon catheter guide wire 15 is then extended to the target lesion
through the inside of the blood vessel 30, as shown in FIG. 8. The guide
wire 15 is left in the blood vessel after it has passed through the
constricted site 32.
The balloon catheter 10 is then advanced through the inside of the blood
vessel 30 along the balloon catheter guide wire 15. The balloon catheter
10 of the present invention has an increased resistance against bending
since the reinforcement 9 is wound about the portion of the outer surface
of the inner tube 1 disposed within the balloon 3, so that, even when the
blood vessel 30 has an acute bend, as shown in FIG. 8, there is no risk of
obstruction of the progress of the balloon catheter guide wire 15 caused
by the breaking of the inner tube 1 within the balloon 3 or the collapse
of the first lumen opened at the end and hence the balloon catheter 10 can
be proceeded smoothly towards the lesion at the distal side.
It should be noted that, when the reinforcement 9 is formed as a wire in
the form of a coil, above all, as a coil spring, which is wound about the
outer surface of the inner tube 1 with the neighboring turns of the coil
in tight and intimate contact with one another, an increased resistance is
obtained against external forces.
When the coil wire has an elliptical, rectangular or a circular
cross-section, a further increase is obtained in the resistance against
external forces.
Also, when the reinforcement 9 is formed of an X-ray opague material, the
reinforcement 9 is indicated as a clear X-ray contrast image, under X-ray
fluoroscopy, such that this reinforcement 9 can be checked visually as an
indicia for the balloon for positively positioning the cylindrical section
3a of the balloon 3 at the stenosis site 32.
It is preferred that the X-ray opague material be platinum, gold,
tungstene, alloys thereof or a silverpalladium alloy, since then a clearer
X-ray contrast image is produced and thus the reinforcement may be used
more effectively as the indicia for the balloon 3.
It is also preferred that, in the state in which the balloon 3 is folded
and wrapped about the inner tube 1, that is, about the tubular member 5,
the portion of the balloon catheter introduced into the patient's body be
of an outside diameter of not more than 2.7 mm, since then the balloon
catheter can be used more advantageously within the body cavity, above
all, within the vessel having a narrower inner cavity.
When the balloon 3 reaches the stenosis site 32, as shown in FIG. 9, the
contrast medium are injected into the dilated space 14 of the balloon 3,
as the contrast medium are pressurized to several to ten and odds
atmospheres, by the injector fitted with a pressure gauge 24, connected to
the injection port 13 of the balloon catheter 10, for expanding the
balloon 3 as shown in FIG. 10 for pressuring and enlarging the diameter of
the stenosis site 32.
After termination of this operation, the contrast medium are injected into
the blood vessel via contrast medium injection port 29 of the Y-shaped
connector 27 connected to the proximal end of the guiding catheter 26 for
visual checking of the distal side blood stream by X-ray fluoroscopy. When
it is observed that the blood stream is improved, the balloon catheter 10
and the balloon catheter guide wire 15 are removed from the blood vessel
30. The guiding catheter 26 is then removed and the pierced portion of the
blood vessel is pressed to stop the hemorrhage to terminate the operation.
The above described balloon catheter is formed by coaxially arranged inner
and outer tubes defining two lumens. However, the present invention may
naturally be applied to a balloon catheter formed by a tubular member
defining a sole lumen.
Referring to FIG. 11, showing a second embodiment of the present invention,
a balloon 3' enclosing the distal part of a tubular member 5' is provided
at the distal part of the tubular member 5' defining the sole lumen 6'.
The reinforcement 9 may be provided at the distal part of the tubular
member 5' surrounded by the balloon 3' for forming a balloon catheter 10'.
This balloon catheter 10' is used for improving the state of stenosis of
the coronary artery, for example. The operation of the balloon catheter
10' is basically the same as that of the above described balloon catheter
10 having the dual tube structure. However, in the present embodiment, the
balloon catheter guide wire 15 is introduced into the lumen 6' at its
proximal end and held so that its distal part does not break the balloon
3'. In this state, the air inside the balloon 3' is replaced by the
contrast medium in the same way as in the preceding embodiment. The
contrast medium are then sucked and discharged in a predetermined amount
using the aforementioned in-deflator to cause the balloon 3' to be wrapped
about the tubular member 5' to reduce the outside diameter of the balloon
3' so that the outside diameter of the portion introduced into the balloon
catheter 10' is not more than 2.7 mm.
Referring to FIG. 12, illustrating a third embodiment of the present
invention, a tubular member 5" defining a sole lumen 6" has a distal
closed end. At the distal part of the tubular member 5" is provided a
balloon 3" enclosing the distal part of the tubular member 5". The lumen
6" of the tubular member 5" may be in fluid communication with an
expansion space 14" of the balloon 3" through an orifice or orifices
formed in the tubular member 5". The reinforcement 9 may be provided at
the distal part of the tubular member 5" surrounded by the balloon 3" and
have turns therof so wound that they be in intimate contact with each
other. The operation of this balloon catheter is substantially same as
those of the above-discribed balloon catheters.
In case of the reinforcement being a coil spring, it may alternatively be
so wound that its turns are thick for example in intimate contact with
each other in both end parts and thin or sparse in the intermediate part
of the coil spring.
The balloon catheter in this state is introduced into the blood vessel 30,
as it is guided by the balloon catheter guide wire 15, until the balloon
3' reaches the stenosis site 32 in the same way as in the preceding
embodiment. The contrast medium are then injected in a predetermined
amount into the expansion space 14' of the balloon 3', with the aid of the
pressure gauge-injector 24, for dilating the balloon 3' for pressuring and
enlarging the stenosis 32.
When it is observed that the state of the blood stream is improved, the
balloon catheter 10' may be removed from the inside of the blood vessel,
as described hereinabove.
In the present second embodiment, by providing the reinforcement 9 at the
forward side of the tubular member 5', the tubular member can be
reinforced against buckling.
EFFECT OF THE INVENTION
As described in detail, the present invention provides a balloon catheter
comprising a tubular body including at least one lumen, and a foldable
balloon provided at a predetermined distal portion on the outer surface of
said tubular body so that the balloon communicates with at least one lumen
in said tubular body, wherein a reinforcement is provided at a
predetermined portion on the outer surface of said tubular body surrounded
by said balloon.
With the above described arrangement of the balloon catherter, the balloon
portion of the balloon catherter may positively be proceeded to the target
lesion, without breaking and collapsing of the tube portion enclosed in
the balloon even at progress through an acute bend of the blood vessel.
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