939-81 Thrombolysis Enhanced by Ultrasound on Intracoronary Thrombus

The synergistic effect of combined usage of ultrasonic irradiation and t-PA was examined on intracoronary thrombus, produced in the canine left anterior descending artery (LAD). t-PA was given as a bolus dose of 0.1mg/kg followed by an infusion of 0.9mg/kg in one hour, until recanalization (TIMI 2). Canines were randomly divided into two groups, one of which (n=5) received continuous ultrasonic irradiation (200kHz, 0.25W/cm2) directly to the LAD occluded by thrombus. The other group (n=4) served as the unirradiated control. Ultrasonic irradiation significantly reduced both the time required for recanalization (irradiated 13.6±6.0min. vs. control 36.0±18.0min.; p<0.05) and the administered dose of t-PA (0.32±0.11mg/kg vs. control 0.64±0.27 mg/kg; p<0.05). Upon electron microscopical examination, ultrasonic irradiation had no damage on the tissue morphology. This simple method safely could enhance the thrombolytic effect of t-PA and could make rapid coronary recanalization and reduction the dose of t-PA. We expect this method may be applied to the treatment of acute myocardial infarction