Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-03-08
2003-12-02
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S167030, C604S164130, C604S528000, C606S194000
Reexamination Certificate
active
06656153
ABSTRACT:
TECHNICAL FIELD
IABP is a method for treatment when the heart functions decline due to cardiac insufficiency etc. and is designed to assist heart functions by the insertion of a balloon catheter in the aorta and expanding and contracting the balloon portion along with the beating of the heart.
BACKGROUND ART
IABP is a method for treatment when the heart functions decline due to cardiac insufficiency etc. and is designed to assist heart functions by the insertion of a balloon catheter in the aorta and expanding and contracting the balloon portion along with the beating of the heat.
Various balloon catheters used for such IABP have been proposed (Japanese Unexamined Patent Publication (Kokai) No. 63-206255, Japanese Unexamined Patent Publication (Kokai) No. 62-11456, etc.)
In such balloon catheters, there is known a so-called double lumen type balloon catheter in which the balloon catheter is inserted into a blood vessel along a guidewire so as to enable the balloon portion to be guided to a predetermined position close to the heart in the arterial blood vessel. This balloon catheter has an inner tube arranged inside an outer tube forming the catheter tube. The lumen of the inside of the outer tube serves as a flow channel for a shuttle gas for causing the balloon portion to expand or contract, while the lumen of the inner tube serves as a through hole for the guidewire for guiding the balloon portion to the predetermined position near the heart in the artery.
In such a balloon catheter having an inner tube, however, there is the following problem. That is, the outer tube forming the catheter tube is supposed to be inserted inside the artery of the patient, so considering the discomfort to the patient, in particular the circulation of the blood from the point of insertion to the tissue at the terminal side, preferably should be as small in outer diameter as possible.
If the outer diameter of the outer tube is small, however, the cross-section of the flow channel of the lumen formed inside it becomes small. The inside of the outer tube also has the inner tube disposed in it so the actual cross-sectional area of the flow channel for the circulation of the gas is reduced even more. To enlarge the actual cross-sectional area of the flow channel in the lumen of the outer tube, it is preferable that the outer diameter of the inner tube also be small. The lumen of the inner tube, however, has the guidewire inserted through it, so there is a limit to how small the outer diameter of the inner tube can be made.
The lumen of the outer tube other than the cross-section of the inner tube is passed through by the gas for causing the expansion and contraction of the balloon portion. If the outer diameter of the outer tube is made small, the cross-sectional area of the flow channel of the lumen becomes increasingly small, the resistance of the flow channel increases, the response of expansion and contraction of the balloon portion driven by the gas becomes poorer, and consequently a timing lag of the expansion or contraction is liable to occur and assisting action to the heart can not be achieved effectively.
The period of expansion and contraction of the balloon portion is, for example if the heart beat is 100 beats per minute, a period of 0.6 second. The gas passes back and forth inside the lumen of the outer tube within a time shorter than that period, so the smaller the resistance of the flow channel the better.
As explained above, however, the inner tube is placed inside the lumen of the outer tube and there are limits to how small the outer diameter of the inner tube can be made. Further, there are limits to how small the outer diameter of the outer tube can be made.
Therefore, in the prior art, there was no choice but to set the outer diameter of the outer tube forming the catheter tube as large as possible within a range not causing a remarkable increase in the discomfort to the patient. In order to obtain a satisfactory level of response in the expansion and contraction of the balloon portion, the discomfort to the patient was unavoidably increased to a certain extent.
DISCLOSURE OF THE INVENTION
The present invention was made in consideration of this actual situation and has as its object the provision of an innovative balloon catheter which enables an improvement in the response of expansion and contraction of the balloon portion despite being able to reduce the outer diameter of the outer tube forming the catheter tube and alleviating the discomfort to the patient.
To achieve the above object, the first balloon catheter according to the present invention comprises an outer tube having a first lumen inside the outer tube, a balloon portion having a proximal end of the balloon portion joined to a distal end of the outer tube and a distal end of the balloon portion joined to a tubular shaped front tip portion in order to form a balloon space inside the balloon portion, into which a pressurized fluid is introduced and released from through the first lumen of the outer tube to give an expanded and contracted state, and an inner tube having a second lumen inside the inner tube extending inside the first lumen of the outer tube to freely slide in the axial direction, projecting out from the distal end of the outer tube, and detachably attached to the front tip portion.
The second balloon catheter according to the present invention comprises an outer tube having a first lumen inside the outer tube, a balloon portion having a proximal end of the balloon portion joined to a distal end of the outer tube and a distal end of the balloon portion joined to a tubular shaped front tip portion in order to form a balloon space inside the balloon portion, into which a pressurized fluid is introduced and released from through the first lumen of the outer tube to give an expanded and contracted state, and a valve element through which a guidewire extending inside the first lumen of the outer tube to be freely slidable in the axial direction can be passed in a detachable manner, the valve element being attached to the front tip portion so as to maintain the inside of the balloon portion sealed in both the state with the guidewire attached and the state with the guidewire not attached to the valve element. Note that in the present invention, the “guidewire” is not particularly limited in material. The term is used in the sense including a member comprised of a rod made of a synthetic resin in addition to an ordinary metal guidewire.
In the present invention, the cross-sectional shape of the outer tube is not particularly limited. It may be circular or polylateral in shape, but a circular shape is preferable. At the inside of the outer tube is formed a lumen along the longitudinal direction.
In the present invention, the balloon portion is formed by a tubular film in which a balloon space is formed. In the expanded state, it has an outer diameter larger than the outer tube. In the expanded state, the cross-sectional shape of the balloon portion is not particularly limited and may be circular or polylateral, but it is preferably circular.
At the inside of the tubular front tip portion is preferably attached a valve element sealing the balloon space inside the balloon portion from the outside of the balloon portion. To this valve element, preferably a distal end of the inner tube (or guidewire) is detachably attached. This valve element can seal the balloon space at the inside of the balloon portion from the outside of the balloon portion both in a state with the distal end of the inner tube (or guidewire) attached to the valve element and in a state with the inner tube (or guidewire) detached. The valve element is not particularly limited. It is not limited to a duckbill valve or other hemostatic valve normally used as a medical part. A three-way cock valve, compression spring valve, water absorbing polymer slit valve, etc. may also be mentioned.
The valve element preferably used in the present invention is formed with a tight-fit hole. In the state with the distal end of the inner tube inserted into the ti
Iida Takahiro
Sakai Kouichi
Toyokawa Tetsuo
Armstrong Westerman & Hattori, LLP
Casler Brian L.
Nippon Zeon Co., LTD
Serke Catherine
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