773-2 Can Low-Temperature, High-Frequency Radio Energy PTCA Influence Restenosis?

Abstract

Radio frequency (RF) PTCA has previously been used with relatively low RF energy (0.25 MHz) producing primarily heat to facilitate lesion dilitation. At this low frequency (F), the RF energy does not penetrate beyond the balloon material and therefore is converted to heat within the confines of the balloon. A new device with a high-F source (13.56 MHz) not only affects balloon temp(T), but also directs electromechanical radiation to susceptible cellular components. 16 rabbits underwent bilateral focal femoral artery injury by air desiccation, followed by an atherogenic diet (1% cholesterol, 6% peanut oil) for 28 days. Femoral artery PTCA was performed with a 2.5 mm balloon catheter, following a protocol (3 inflations, 6 atmospheres, 60 sec.) on one femoral artery, while the opposite femoral artery underwent 3 successive RF PTCA's at 13.56 MHz, restricting T to 55 C. Angiograms were performed pre-PTCA, following PTCA, and approx. 3 weeks later at the time of sacrifice. Analysis of vessel dimensions, and percent stenosis were done by independent, blinded, quantitative measurement (QCA). There were no Significant differences seen in either group with regard to normal reference vessel size, lesion MLD, or diameter stenosis. Importantly, subsequent angiographic lesion progression was significantly limited in the RF PTCA group (8% MLD reduction) vs. the PTCA group (23% MLD reduction). Preliminary results in this restenosis model are encouraging and warrant further investigation.