[Angioplasty using high-frequency energy in coronary stenosis]

The most notable limitations of balloon dilatation, acute vascular occlusion with a rate of 3 to 5% and restenosis rate of 20 to 40%, appear at least partially attributable to the mechanism of luminal widening--tearing of the intima and plastic restructuring of plaque material. Alternative angioplasty methods, with the exception of stent implantation, are based on the concept of rendering plaque material, by excision and ablation, with a smoother and less thrombogenic interior surface and to lower the risk of renewed proliferation. Plaque material is removed in three ways: mechanical, by excision; thermically, by laser with relatively low energy density or by high-frequency alternating current; non-thermically, by photoablation with laser of very high energy impulse density. High-frequency alternating current as an energy source for thermic angioplasty is used in four technically different forms of application (Table 1): as indirect or direct high-frequency angioplasty in the scope of the "spark erosion" technique and for heating a balloon during balloon dilatation to achieve thermofusion of the tissue for stabilization of the angioplasty results. With indirect hot-tip high-frequency angioplasty the high-frequency alternating current is employed to rapidly heat an olive-shaped fully isolated metal tip with an integrated resistor, plated with gold to avoid adhesion of thrombotic material. The heat emitted is directed radially. The currently-available system consists of a 20-Watt high-frequency generator with 5 MHz. On application of 10 Watts to tissue in water at 37 degrees C, the temperature achieved at the catheter tip is 130 to 140 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)