USE OF THERAPEUTIC ULTRASOUND IN PERCUTANEOUS CORONARY ANGIOPLASTY - EXPERIMENTAL IN-VITRO STUDIES AND INITIAL CLINICAL-EXPERIENCE

Background Previous studies have shown the feasibility of peripheral a rterial ultrasound angioplasty. Methods and Results In this report, we describe the use of percutaneous therapeutic ultrasound for coronary angioplasty. In vitro, 11 postmortem, atherosclerotically occluded cor onary arteries were obtained to assess catheter-delivered ultrasound f or arterial recanalization as well as for assessment of the size of pa rticulate debris. Clinically, coronary ultrasound angioplasty was perf ormed in 19 patients (mean age, 56 years) to assess safety and feasibi lity for the treatment of obstructive coronary atherosclerosis. Three patients with unstable angina and 16 with exercise-induced myocardial ischemia were treated with a prototype 4.6F coronary catheter ultrasou nd ablation device with a 1.7-mm diameter ball tip. The ultrasound cor onary catheter delivered ultrasound energy at 19.5 kHz, with a power o utput of 16 to 20 W at the transducer. Energy is delivered in a pulsed mode with a 50% duty cycle of 30 milliseconds. Patients were treated for a mean of 493 seconds (range, 130 to 890) with intracoronary ultra sound ablation. All lesions were treated with adjunctive balloon angio plasty. All 11 postmortem coronary occlusions were recanalized, and 99 % of the particulates generated were <10 mu m in diameter. We found th at after ultrasound, mean (+/-SD) coronary arterial stenosis fell from 80+/-12% to 60+/-18% (P<.001) and to 26+/-11% (P<.001) after adjuncti ve balloon angioplasty. Mean pressures required to achieve full balloo n inflation were 2.7 atm (range, 1 to 5.5) with a median of 3.0-mm bal loon size (2.5 to 3.5). No ultrasound-related complications were ident ified. Conclusions Intracoronary ultrasound plaque ablation appears to be safe. Our findings suggest that catheter-delivered high-intensity, low-frequency ultrasound may be useful for lesion debulking and enhan cing arterial distensibility, allowing balloon dilation at relatively low pressures.