Balloon catheters are used in a variety of medical procedures. For example, in the well-known procedure of percutaneous translumenal coronary angioplasty (PTCA) a balloon catheter is inserted into a coronary artery. Then, the balloon of the catheter is inflated, to force expansion of the walls of the coronary artery to increase the blood flow capacity of the artery, which has been typically reduced by arteriosclerotic lesions.
Catheter balloons for PTCA must be quite strong, to withstand significant inflation pressures. Accordingly, they tend to be somewhat stiff, since their wall thickness must be sufficient to provide the necessary strength. Thus, when deflated, such catheter balloons can flatten in a phenomenon known as "winging", in which the flat, lateral portions of the deflated balloon project laterally outwardly well beyond the rest of the catheter. This is deemed to be undesirable by many practitioners, because of a concern that the flat wings may damage the artery wall as the deflated balloon is advanced through the arterial system into the desired position for inflation. Also, such flat wings can interfere with the manipulation of the catheter and its easy advancement through the arterial system.
In accordance with this invention, an improved balloon configuration for a balloon catheter is provided, to eliminate the undesired "winging" phenomenon which is encountered when the catheter balloon is in deflated condition. Also, the catheter balloon may be stronger than prior art catheter balloons, with improved tensile strength, while exhibiting a reduced wall thickness to improve the flexibility of the balloon. Thus, with the catheter balloon of this invention, PTCA procedures can be performed more effectively, with less concern about damage to coronary arteries by the "winging" phenomenon of the deflated catheter balloon, and with greater ease of catheter advancement through the arterial system.