[Removal of intravascular thrombi by means of ultrasonics. Experimental study with a new method and its clinical use].

A new method of destroying thrombi in blood vessels by ultrasound and simultaneously removing them is reported. Experiments were performed in 19 dogs with artificial thrombi in the iliac and the femoral arteries and veins. The length of the thrombi ranged from 4 to 5 cm and the age from 12 h to 9 days. The unit used consisted of a generator, a frequency counter, an ultrasonic transducer with the hollow waveguide, and a vacuum pump. For protection of the vessel wall the guide is surrounded by a plastic tube. The ultrasonic frequency is 26.5 kHz, the amplitude 25--30 micrometer. The time needed to destroy the thrombus by ultrasound and suck out the thrombotic material ranged from 2.5 to 5 min. To check side effects, experiments were performed in 48 dogs. No changes resulting from ultrasonic irradiation were seen in the circulating blood or in the microscopic structure of the vessel wall. Ultrasonic thrombolysis was performed in a 42 year old patient with a 2-day-old thrombosis of the femoral artery. After 4.5 minutes of intermittent ultrasonic irradiation the artery was patent.