Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-06-04
2003-03-25
Reip, David O. (Department: 3731)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C606S194000
Reexamination Certificate
active
06537247
ABSTRACT:
BACKGROUND ART
The present invention is related to methods and apparatus for clearing blocked natural and synthetic body lumens. More specifically, this invention is related to methods and apparatus for percutaneously altering balloon configuration during clearing of blocked natural and synthetic body lumens by use of a strain relief tube, whereby the use of such balloon procedures is broadly enabled, and wherein the functional utility, ease of use, and wide applicability of the device in medical practice constitutes progress in science and the useful arts. Furthermore, the present invention teaches processes for the use of the device in medical practice.
A variety of techniques and instruments have been developed for use in the removal or repair of obstructive material in lumens such as vessels and other body passageways. Such material may include atheromas, thrombi, or emboli. An atheroma is a mass of plaque of degenerated, thickened arterial intima occurring in atherosclerosis. A thrombus is an aggregation of blood factors, primarily platelets and fibrin with entrapment of cellular elements, frequently causing vascular obstruction at the point of its formation. An embolus is a clot or other plug brought by the blood from another vessel and forced into a smaller one, thus obstructing the circulation.
Balloon catheters are finding increasing use in medical procedures such as percutaneous transluminal angioplasty, valvuloplasties, percutaneous transluminal nephrostomy, ureteral dilation, biliary duct dilation, esophageal tract dilation, cochlear canal dilation, percutaneous transluminal renal angioplasty, and the like. Balloons for use in these procedures have been prepared from a variety of polymeric materials which are blood and tissue compatible. Among those materials that have been employed include materials such as poly(vinylchloride), polyethylene and the like, homopolymers or copolymers of olefins, polyethylene/vinyl acetate copolymers, polyethylene terephthalate (PET), irradiated polyethylene, and polyurethanes.
Several problems exist with respect to the utilization of balloons in these procedures. In the past, medical device balloon materials have included balloons having a wall thickness at which the material exhibits strength and flexibility that allow inflation to a working diameter or designated initial dilation diameter which, once achieved, is not surpassable to any significant degree without balloon breakage or substantially increasing the risk of balloon breakage. Balloons of these materials can be characterized as being substantially non-distensible balloons that are not stretchable, expandable or compliant to a substantial extent beyond this working diameter. Such substantially non-distensible balloons can be characterized as being somewhat in the nature of paper bags which, once inflated to generally remove folding wrinkles, do not further inflate to any significant degree. Polymeric materials of this substantially non-distensible type that are used or proposed for use as medical balloons include polyethylene terephthalates (PET), and irradiated polyethylene.
As an example of such problems, a typical procedure in which balloons are used is percutaneous transluminal coronary angioplasty (PTCA), which is widely accepted as an effective treatment of blockages in the coronary arteries. Blockages (stenoses) may occur from cholesterol precipitation on the coronary wall, which may be in any stage from initial deposit through aged lesions. Coronary arteries can also become blocked due to formation of thrombus.
The most widely used percutaneous coronary angioplasty makes use of a dilation balloon catheter. A catheter is inserted into the patient's vascular system and guided until a balloon at the distal end of the catheter is positioned across the stenosis. The balloon of the dilation catheter must be deflated to a low profile in order for it to be passed through the guide catheter and, more particularly, through the stenosis. The balloon is deflated by applying negative pressure to the balloon through an inflation/deflation lumen that extends from the proximal end of the catheter to the interior of the balloon.
The configuration assumed by the balloon upon deflation presents a problem. Typically, the balloon forms a pair of opposed, radially-extending, flat wings, when collapsed under the influence of negative pressure, which may make passage through the lumen and particularly the obstruction difficult. A radiographic contrast fluid is then passed under pressure through an inflation lumen of the catheter to the balloon, which causes the balloon to expand outward. As the balloon expands, it dilates the lumen of the artery and compresses the stenosis. Upon being compressed, the stenosis may break up or flatten out against the arterial wall. The balloon is subsequently deflated by reducing the applied pressure and, once in its collapsed configuration, it is either withdrawn from the artery or placed across another stenosis, to restore normal blood flow through the artery.
To effectively expand the lumen and compress the stenosis, it is desirable that the balloon be reliably inflatable to a relatively large diameter when the balloon is infused with fluid. This is so in order to expand the balloon evenly within the affected artery to dilate the vessel evenly, compress, and hence compromise the stenosis. Also, it is desirable that the balloon be reliably collapsible to a minimal, radially compact cross sectional shape incident to balloon insertion and withdrawal. This is to facilitate insertion and withdrawal of the balloon in artery. While existing angioplasty balloons are collapsible, it is unfortunately the case that many existing balloons typically cannot be reliably collapsed, i.e., deflated, to a radially compact minimal cross section after inflation. Instead, they often flatten when deflated in a phenomenon known as “winging”, in which the flat, lateral portions, or flaps, of the deflated balloon project laterally outward. This is deemed to be undesirable by many practitioners because of a concern that the flat wings or flaps may damage, e.g., an artery wall, as the deflated balloon is removed from the arterial system. Consequently, a flattened balloon can be relatively difficult to withdraw from an artery, because it is difficult to get large flaps to fold together and squeeze out all of the space between them.
By way of further explanation, the cross-sectional configuration assumed by a typical dilation balloon when the balloon is aspirated by applying negative pressure to the balloon interior, is a pair of diametrically opposed wings as the balloon collapses. The physician typically must manually wrap the wings about its catheter shaft, creating a low profile configuration which permits easy insertion into the lumen of a guide catheter. Difficulty may arise, following the dilation procedure, either when it is desired to withdraw the balloon catheter through the lumen of the guide catheter or when it is desired to deflate the balloon and reposition it at another vascular location to perform another dilation. In particular, the diametrically opposed wings may not wrap closely about the catheter shaft as the catheter is withdrawn back into the guide catheter or is repositioned within the arteries. Instead, the wings may catch on the distal opening of the guide catheter or may preclude reinsertion of the balloon into another stenosis.
A further problem arises in connection with a material such as polyethylene terephthalate (PET). Thus, balloons made of PET that are especially useful in medical dilation procedures have been disclosed in U.S. Pat. No. Re. 33,561 to Levy. Even though PET is advantageous from the point of view of its especially high tensile strength and its tightly.controllable inflation characteristics, it has undesirable properties as well. In some situations, biaxial orientation of polyethylene terephthalate will impart excessive crystallinity to an angioplasty balloon, or the Young's modulus will be simply too high. Under these circumsta
Davis D Jacob
Intellepharm, Inc.
Reip David O.
Wolff Manfred E.
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