Note: Descriptions are shown in the official language in which they were submitted.
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l Back~round of the Invention
This invention relates to a catheter adapted to be
inserted into a blood vessel and more particularly, to a
catheter suitably employed for treatment of heart diseases.
As the conventional medical treatment ~or ischemic
heart diseases such as angina pectoris and myocardial
infarctions, the so-called Percutaneous Transluminal Coronary
Angioplasty method (abbreviated as "PTCA method" hereinafter)
has been known. According to the PTCA method, a catheter tube
having at the distal end an elongated balloon made of
polyurethane or the like is inserted into the stenosis formed
by a thrombus and cholesterol in the coronary, and the balloon
is then positioned within the stenosis and expanded radially
outwardly to expand the stenosis.
In this method, the location of the stenosis is
first determined on the basis of a defective area of the
shadow image given by an angiography and the balloon is then
positioned and expanded.
However, in the above-mentioned PTCA method, which
is more fully described at the end of the disclosure, since
the conditions and nature of the stenosis is judged only from
the unclear shadow image of the angiography, the method cannot
pinpoint the exact conditions and nature of the stenosis and
frequently fails to perform effective treatment. That is, in
spite of the fact that other methods such as laser irradiation
or injection of thrombus dissolving agent for treatment which
depend upon the conditions and nature of the stenosis are
appropriate, there are the cases in which effective treatment
can not be performed because of the use of the PTCA method.
Also, determination made only by means o~ a shadow image
frequently fails to elicit any affirmati~e confirmation as to
whether the balloon is properly positioned with respect to the
constriction. Thus, it is said that the probability of the
stenosis blocking up again after treatment by the conventional
PTCA method is as high as 25-30%.
Summary of the Invention
It is therefore a primary object of the present
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1 invention to provide a catheter which can pinpoint exactly
the conditions and nature of the stenosis to be treated.
According to the present invention, a catheter
adapted to be inserted into a blood vessel comprising a
flexible tube~like sheath including a fluid passage
therein and a radially expansive and contractive balloon
disposed about the peripheral surface of the leading end
portion of said sheath and communicating with said fluid
passage is proposed. A light guide for transmitting
illumination light to the distal end of said catheter, an
image guide such as an image fiber bundle for transmitting
an image from the distal end of said catheter and a
transparent liquid guide passage opening at the distal end
of said catheter are disposed substantially parallel to
each other within said flexible tube-like sheath, the
catheter thereby including the concurrent function of an
endoscope.
In one aspect the invention provides a catheter
for insertion into a blood vessel, comprising a flexible
tube-like sheath having a fluid passage therein; a
radially expansive and contractive balloon disposed about
the peripheral surface of the distal end portion of said
sheath and communicating with said fluid passage; a light
guide for transmitting illumination light to the distal
end of said catheter, an image guîde for transmitting an
image from the distal end of said catheter; and a
transparent liquid guide ha~ing a flush opening at the
distal end of said catheter; wherein said light guide,
said image guide~ and said transparent liquid guide are
disposed substantially parallel with each other within
said flexible tube-like sheath; and wherein said light
guide comprises a single transparent member formed by
extrusion which substantially fills the inside of said
flexible tube-like sheath along the entire length of said
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1 ~lexible tube-like sheath such that said lmage guide and
said fluid passage and said transparent liquid guide are
also formed with said light guide by extrusion of said
single transparent member and disposed within said
transparent member.
With the above-mentioned construction and
arrangement of the components of the catheter according to
the present invention, first of all, the catheter is
inserted into a blood vessel ~Ihile observation is made of
a shadow image given by an angiography until the distal
end of the catheter is positioned immediately short of the
stenosis in the blood vessel. Transparent liquid is then
spouted through the flush openings at the distal end of
the catheter and the conditions and nature of the stenosis
are observed through the image fiber bundle while a visual
field is maintained in the blood vessel. When it has been
determined by observation that the conditions and nature
of the stenosis are suitable for treatment by the PTCA
method, the catheter is further advanced into the blood
vessel, and after it has been confirmed that the catheter
has been properly positioned with respect to the stenosis
by means of the image fiber bundle, the balloon is
expanded radially outwardly to expand the stenosis. After
the catheter has been pulled out of the stenosis, it can
be confirmed whether the stenosis has been properly
expanded or not by observation through the image fiber
bundle.
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Many other advantages, features and additional
objects of the present inven~ion will become apparent to
persons skilled in the art upon making reference to ~he
detailed description and thP accompanying drawings in which
preferred embodiments of the present invention are shown by
way of illustrative example.
Brief Description of the Drawings:
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Fig. 1 is a longitudinally sectional view of thedistal end portion of a first embodiment of the catheter
according to the present invention;
Fig. 2 is an end elevational view of the leading end
portion of the catheter as shown in Fig. l;
Fig. 3 is a fragmentary longitudinally sectional view
showing the construction of the branching portion of the
catheter as shown in Fig. l;
Fig. 4 is a cross sectional view of said branching
portion as shown in Fig. 3;
Fig. 5 is a longitudinally sectional view of the rear
end portion of the catheter, where the catheter is connected
to the light source, as shown in Fig. l;
Fig. 6 is a longitudinally sectional view showing the
operation of the catheter as shown in Fig. l;
Fig. 7 is a side elevational view of the distal end
portion of a second embodiment of the catheter according to
the present invention;
Fig. 8 is a view similar to Fig. 2 but showing a
third embodiment of the catheter according to the present
invention; and
Fig. 9 is a fragmentary longitudinally sectional view
showing the steps of the operation of a conventional cathe-
ter in the PTCA method.
Detailed~Descri tion of the Preferred Embodiment~:
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The present invention will now be described with
reference to the accompanying drawings in which preferrad
embodiments of the present invention are illustrated. Figs.
1 and 2 show the construction of the distal end p~rtion of
a first embodiment of the catheter 4' according to the
present invention. In these Figures, 5 denotes a light
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guide having a substantially circular cross section for
transmitting illumination light therethrough, 6 denotes a
through bore formed within the light guide S and having its
axis substantially parallel to that of the light guide, 7
denotes an image fiber bundle image transmitting disposed
within the through bore 6 and pro~ided at the distal end with
object lenses 8, 9 denotes transparent liquid guide passages
disposed within the light guide 5 and having their axes sub-
stantially parallel to those of the light guide and through
bore (in the illustrated embodiment, two adjacent passages
are provided~, said transparent liquid guide passages 9 having
flush openings at the distal ends thereof, 10 denotes a
flexible radioopaque outer sheath (containing BiClO, Bio or
BaSO4) surrounding the light guide 5, and 11 denotes an
expansive and contractive balloon provided about the
peripheral surface of the distal end portion of ~he catheter.
The light guide 5 is formed of transparent material
such as polymethyl methacrylate, polybutyl methacrylate,
copolymer of these materials, polystyrene or polycarbonate
and as shown in Figs. 1 and 2, the light guide 5 is substan-
tially solid within the sections of the catheter except for
the portions containing the image fiber bundle 7, through
bore 6 and transparent llquid guide passage 9. In fact, the
light guide 5 is formed by extrusion so as ~o include the
through bore 6 and transparent liquid guide passages 9
therein. Although not shown, the outer surface of the light
guide is provided with a cladding layer.
The outer surface of the image fiber bundle 7 dis-
posed within the through bore 6 is covered by a light
shielding coat 12 and the leading end portion of the image
fiber bundle 7 and the objective lenses 8 are sealingly fixed
to the inner wall of the through bore 6 with a sleeve 13
interposed therebetween. An annular clearance 14 defined
between the outer surface of the image fiber bundle 7 and
the inner surface of the through bore 6 in a position to
th~ rear of the sleeve 13 provides a fluid passa~e through
which fluid for expanding and ¢ontacting the expansive and
contractive balloon 11 flows. The fluid passage 14 is in
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communication with the interior of the balloon 11 through an
opening 15 which extends through the light guide 5 and outer
sheath 10. The fluid for expanding and contracting the
balloon 11 may be a normal saline solution or grape sugar
solution. The balloon 11 is formed of polyurethane, poly-
olefin (e.g. polyethylene, polypropylene, ethylene propylene
copolymer etc.) or ethylene vinyl acetate copolymer and when
expanded, presents a cylindrical configuration.
Figs. 3 and 4 show the construction of the branch
portion of the above-mentioned embodiment of the catheter.
The image fiber bundle 7 is pulled out of the catheter
through a through hole 16 formed in the light guide 5 and
outer sheath 10 and a tube 17 is inserted at one or the
inner end into the through bore 6 with the other or outer
end pulled out of the catheter through a through hole 18
formed in the light guide 5 and outer sheath 10. Liquid
flows through the tube 17 to expand and contract the balloon
11. The distal end of a second tube 19 for supplying trans-
parent liquid for the purpose of making a flush is bifurcated
into two tube branches 20. Each of the tube branches 20 is
connected at one end to the associated one of the two trans-
parent liquid guide passages 9 and the other end of each tube
branch 20 is then pulled out of the catheter through holes in
the same way as stated when referring to tube 17. Each of
the through holes through which the image fiber bundle 7 ~nd
tubes 17, 20 having been pulled are then sealed with resin.
Also, the portions of the through bore 6 and transparent
liquid guide passage 9 positioned rearwardly of the branch-
ing portion of the catheter are filled with resin 21 and 22,
respectively. The image fiber bundle and tubes branched in
this way are held in position by a split mount 23 provided
with grooves for receiving the fiber bundle and tubes,
respectively. The exposed portion of the image fiber bundle
7 is covered by a protective coating 24.
Fig. 5 show6 the proxLmal end portion of the embodi-
ment of the ca~heter described hereinabove. The proximal end
portion of the light guide 5 is surrounded hy a plug 25 which
is adapted ko be connected to an illumina~ion light source
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(not shown). The plug 25 holds a cylindrical glass block 26
or polymethylmethacrylate block having substantially the same
diameter as the light guide 5 and in close contact wlth the
proximal end face of the light guide 5 to thereby protect the
light guide agaist possible thermal and mechanical damage.
With the above-mentioned construction and arrangement
of the components of the catheter of the invention, as shown
in Fig. 6, the catheter 4' is inserted into a blood vessel 1
and is advanced within the blood vessel until the leading
end of the catheter reaches a position immediately short of
the stenosis 2 of the blood vessel 1 while observation
is made of the movement of the catheter through an angio-
graphy. Then, transparent flush liquid 27 under pressure is
passed through the transparent liquid guide passages 9 to be
spouted at the flush openings of the passages whereby the
spouted transparent liquid 27 temporarily displaces the
blood 28 to form a visual field in front of the catheterO
At this time, when the balloon 11 is caused to expand
temporarily for interrupting the flow of the blood through
the blood vessel 1, the visual field can be easily formed.
Under such condition, the illumination light 29 projected
from the leading end o~ the light guide 5 illuminates the
stenosis 2 and it can be observed through the objective
lenses 8 and image fiber bundle 7. When it has been found
that the conditions and nature of the constriction 2 are
suitable for treatment by the PTCA method, the catheter 4'
is further advanced into the blood vessel 1 until the
balloon 11 is properly positioned with respect to the
itenosis 2 whereupon the balloon is caused to expand
radially outwaxdly such as to expand the stenosis 2.
The positioniny of the balloon 11 and the results of the
treatmen~ can be similarly observed through the lenses 8
and the image fiber bundle 7.
Fig. 7 shows another or second embodiment of the
catheter according to the present invention. According to
the embodiment of Fig. 7, the ligh~ guide 5 including the
through bore 6 and transparent liquid guide passages 9
therein is first formed by extrusion and, then, the portion
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30 of the light guide 5 where the balloon 11 is to be
mounted is reduced in outer diameter by thermal def3rmation.
By this, when the balloon 11 mounted on the portion 30
contracts, the outer surface of the balloon lies in the
plane of the rest of the light guide 5 so that the catheter
can be smoothly inserted into the blood vessel 1 and any
pain which the patient may feel at the insertion of the
catheter into the patient's blood vessel can be alleviated~
The construction and arrangement of the other components of
the second embodiment are the same as those of the corre-
sponding components of the first embodiment.
Fig. 8 shows another or third embodiment of the
catheter according to the present invention. According to
the embodiment of Fig. 8, instead of providing the light
guide 5 and the transparent liquid guide passages 9 sepa-
rately within the section of the catheter as shown in the
first embodiment, a single channel 31 having a re1ective
inner surface 32 is formed in a material 33 filling the
section of the outer tube-like sheath 10 and this single
channel 31 serves concurrently as both the light guide and
the transparent liquid guide passage. The cross sectional
configuration of the channel 31 is semilunar in shape with
the concave side ~hereof facing the image fiber bundle 7 in
order to make the section of the channel 31 as large as
possible while keeping the outer diameter of the endoscope
as small as possible, ~rhe reflective inner surface 32 of
the channel 31 is formed by a coating of aluminum or gold
film vapor-deposition. The illumination light is introduced
into the channel 31 through an optical fiber bundle which is
sealingly inserted into the channel. By this arrangement,
the outer diameter of the endoscope can be made much smaller
than that of the first embodLment. If desired, the above
stated channel 31 may also be used as a channel for feeding
forceps. Namely, there are cases in which an affected part
3~ or parts of the interior of the blood ve sel not only need
to be examined but also need to be cut out. In ~uch cases,
the chann~l 31 may altexnati~ely be us~d :Eor gui~ing trans-
parent liquid or feeding forcepsD ~ large cro~s section of
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1 the channel 31 will suffice in preventing any interference
with the passage of light through the channel when forceps are
also being fed through the channel.
With reference now to Figs. 9(a) - (b), which show
the steps of the operation of a connecting catheter in the
PTCA method, a catheter tube 4 having at the distal end an
elongated balloon 3 made of polyurethane or the like is
inserted into the stenosis 2 formed by a thrombus and
cholesterol in the coronary 1, and the balloon is then
positioned within the stenosis and expanded radially outwardly
to expand the stenosis.
In this method, the location of the stenosis is
first determined on the basis of a defective area of the
shadow image given by an angiography and the balloon is then
positioned and expanded.
As will be clear from the foregoing description on
the preferred embodiments of the present invention, since the
catheter according to the present invention concurrently
functions as an endoscope, the inventive catheter can directly
observe ~he conditions of the stenosis of the blood vessel,
this having been impossible with the prior art catheters.
Thus an appropriate treatment is ensuredD Furthermore, since
the positioning of the balloon and the post-treatment
conditions can be directly observed, the chance o~ errors
occurring in treatment can be substantially reduced.
Furthermore, since a single catheter can concurrently perform
both examination and treatment ~unctions, the frequency of the
insertion oE the catheter into the patient's blood vessel for
a particular examination and/or treatment is reduced whereby
the pain experienced by the patient can be alleviated
accordingly.
