Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent in combination with graft
Reexamination Certificate
1999-08-04
2002-04-02
Prebilic, Paul B. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent in combination with graft
C623S001510, C139S38700A
Reexamination Certificate
active
06364901
ABSTRACT:
FIELD OF THE INVENTION
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
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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 covere
Banner & Witcoff , Ltd.
Prebilic Paul B.
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