FEASIBILITY OF RECANALIZATION OF HUMAN CORONARY-ARTERIES USING HIGH-INTENSITY ULTRASOUND

To investigate the feasibility of ultrasonic recanalization of obstruc ted human coronary arteries in vitro, high-intensity ultrasound was ap plied to 16 coronary arteries obtained at autopsy, using a prototype i nstrument enabling insonification through a catheter tip. It was 119 c m long, 0.95 mm thick wire in an 8Fr catheter connected to an external ultrasonic transformer and power generator. A 5 MHz phased-array 2-di mensional echocardiography instrument was used to determine minimal lu minal diameter and percent diameter narrowing before and after ultraso und application. The ultrasonic energy was delivered at 21.5 kHz and w ith a 52 +/- 19 mum average amplitude of tip displacement. The mean pe rcent luminal diameter narrowing, flow rate and mean pressure gradient before ultrasound exposure were 74 +/- 11%, 97 +/- 61 ml/min, and 92 +/- 18 mm Hg, respectively. After recanalization, the mean percent lum inal diameter narrowing decreased to 45 +/- 17% (p < 0.001), the mean flow rate increased to 84 +/- 92 ml/min (p < 0.001), and the mean pres sure gradient was reduced to 45 +/- 24 mm Hg (p < 0.001). Of the debri s particles, 95% had a diameter <9 mum (range 5 to 12). Arterial perfo ration occurred in 5 of 16 arteries (31%) and all 5 occurred due to st iff wire manipulation and without ultrasound application. Mechanical f racture of the wire occurred in 8 cases (50%). No signs of thermal inj ury were found on histology. Thus, ultrasonic recanalization of human coronary arteries in vitro is feasible. It may reduce obstruction and improve blood flow. Debris sizes are sufficiently small to minimize th e hazard of peripheral embolization.