Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-10-20
2001-02-20
Nguyen, Anhtuan T. (Department: 3734)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S103070, C604S509000
Reexamination Certificate
active
06190356
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to balloon catheters, and more particularly to catheters for use in centering a central support tube in a blood vessel for use in a medical treatment process.
2. Description of Related Art
Several designs of dilatation balloon catheters have been proposed in the prior art, examples of which can be seen in U.S. Pat. No. 5,160,321; U.S. Pat. No. 5,090,958; U.S. Pat. No. 4,787,388; and U.S. Pat. No. 4,581,017. Each of those balloon dilatation catheters was designed for the purpose of administering treatments to physically widen constricted blood flow passages. The term stenosis is used in this regard to refer to a region of a blood vessel which has been narrowed or constricted to such a degree that blood flow is restricted. In severe instances, treatment of the stenosis is required. Treatment of coronary blood vessels by use of the aforenoted prior art dilatation balloon catheters is referred to in the art as percutaneous transluminal coronary angioplasty (PTCA), which procedure is described in various forms in the patents identified above. The term “dilatation catheter”, as used herein, will refer to the type of catheter which is principally designed for use in widening constricted blood flow passages, as is done in the PTCA procedure.
One problem associated with PTCA which has been recognized in, for example, U.S. Pat. No. 4,581,017, issued to Sahota, and U.S. Pat. No. 4,787,388, issued to Hofmann, is that, in performing the PTCA procedure, blood flow cannot be completely occluded for extended periods of time, measured in terms of well under one minute, due to the increased probability that serious damage to the patient's heart or other downstream vessels or organs will occur. The Sahota patent presents two approaches to solving this problem, a first of which is to provide a balloon catheter which, even though the inflated balloon completely occludes the blood vessel, i.e., the balloon inflates into contact with the blood vessel around the entire circumference of the blood vessel, blood is permitted to flow from a proximal side of the balloon to the distal (downstream) side of the balloon through a central lumen. The second solution proposed by Sahota, which appears to be conceptually the same as the Hofmann solution, is to design the balloon such that, when the balloon is expanded or inflated, it will not completely occlude blood flow, but which will, at the same time, provide sufficient area of balloon contact around the circumference of the blood vessel such that the tissue or other matter creating the constriction in the blood vessel can be compressed against the vessel wall in an effective manner. These designs purport to permit a longer dilatation period to be used when performing the PTCA procedure.
A further balloon catheter design of which the present inventor is aware is disclosed in U.S. Pat. No. 4,762,130, issued to Fogarty et al. This catheter was not designed as a dilatation catheter for use in performing the PTCA procedure, but instead was developed for use in removing blood clots from blood vessels, and also for use as a diagnostic tool carrying diagnostic equipment in a lumen or lumens associated with the catheter. The corkscrew shape of the balloon on this catheter was adopted specifically to avoid the application of diametrically opposed forces on the wall of the blood vessel, so as to minimize the possibility of abrasions and/or perforations occurring in the vessel wall. As such, this balloon catheter would be particularly unsuitable for use in performing the PTCA procedure or for other procedures requiring some amount of diametrically opposed force or other opposing forces to be applied.
It has previously been noted that dissection of the blood vessel is a potential problem in performing the PTCA procedure, and one or more of the aforenoted patents directed to a dilatation catheter discuss procedural steps which attempt to minimize the possibility that dissection will occur. None of the above-noted dilatation catheter patents discusses providing a balloon-type catheter having a balloon configuration which is especially well-suited for use in repairing or tacking such dissections.
It is a principal object of the present invention to provide a balloon-type catheter having features making it especially well-suited for use in processes that call for medical treatment to be administered from inside a blood vessel, and that require the treatment agent to be centered in the blood vessel to the greatest degree practicable.
It is a further principal object of the present invention to provide a balloon-type catheter in which a plurality of balloons are configured in a helical or spiral pattern extending around a central support tube or lumen, whereby a medical treatment can be administered from inside the blood vessel while preserving blood flow down the main trunk or blood vessel, and also in side branches extending from the main trunk.
SUMMARY OF THE INVENTION
Since the issuance of U.S. Pat. No. 5,383,856, to the instant inventor, it has further been determined that a balloon catheter having a central support tube and a plurality of balloon elements extending helically around the central tube can advantageously be used in medical procedures in which the treatment or therapy is to be administered by holding a therapeutic agent in a central portion of a blood vessel for a predetermined period of time. The catheter device for administering therapy from within a blood vessel preferably will have diametrically opposed forces, or forces applied at substantially equal distances around the periphery of a cross-section of the blood vessel, thereby keeping the central support tube substantially centered in the blood vessel, and will, at the same time, permit blood to flow past the balloons, even when inflated.
One type of therapy that is currently being explored is a radiation therapy in which the object is to center, in an artery or other blood vessel, a radium implant, for periods of time on the order of fifteen minutes. For such radiation treatment, it is important to position the radium implant as closely as possible to the center of the artery. It is also important that blood flow past the implant be maintained, so as to not further disrupt normal body functions.
The balloon catheter of the present invention provides a configuration which permits continued perfusion along the main blood vessel in which the medical treatment is being performed, and provides improved protection of flow to side branch blood vessels extending from the main blood vessel, all while the balloons of the catheter are expanded or inflated and are performing their function of centering the central support tube. Both of these features have been determined to be of substantial importance in a balloon catheter whose principal purpose is to permit the use of medical treatments which last for an extended duration, such as on the order of at least several minutes, and in which it is desired or required to keep the treatment agent equally spaced from the side wall of the blood vessel.
In one or more of the above-noted patents disclosing dilatation catheter devices, the desirability of retaining blood flow down the main blood vessel being treated was recognized, even for relatively short-term occlusion of the blood vessel by the catheter. However, none of those patents discuss the importance of protecting (by preserving) blood flow into said branch vessels. This is likely due to the fact that the dilatation balloon catheters, even when inflated for what would be considered to be extended periods of time in the PTCA procedure, would be inflated and blocking off most, if not all, side branch flow for a time measured in terms of seconds, or at most in terms of a minute or two. In contrast, the medical treatment from within a blood vessel may require on the order of fifteen minutes, and possibly, as techniques improve, on the order of one to several hours or up to approximately one day or more. These medical treatments g
Kerins John C.
Miles & Stockbridge P.C.
Nguyen Anhtuan T.
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