[Transluminal coronary angioplasty using ultrasound]

The application of ultrasonic energy for ablation of atherosclerotic plaques was studied. This study was performed in 92 segments obtained from human coronary arteries which belonged to eleven hearts obtained from patients who have died from acute myocardial infarction. An ultrasound generating system (Cavitron 600) was used, and an ultrasonic probe wire (P-150 Endosonic), was attached to it. A stainless steel wire (0.36 mm in width and 145 cm length), was fixed to this probe. Sonic pulsed stimulations 20 sec long and 25 kHz in frequency were performed. The sound transmitting characteristics of the angioplasty guide wire were studied, as well as the ultrasound effects upon atherosclerotic plaques, blood elements, coagulation, and it's lysis effects upon recently formed clots. The anatomic pieces were filmed in cineangiocoronary graphy in two planes, anterior right oblique an anterior left oblique, to be studied later under light microscopy. The results were as following: in the 100% obstructions, a 41% recanalization was obtained; in the 95% obstructions, a 79%, in the 75% obstructions, a 37%. We did not work in the 50% or less obstructions. Under the procedure, no artery suffered perforations. Under Light microscopy, a plaque fragmentation was observed in 24% of the cases; rupture and fragmentation, in 14%, cavitations in 10%; ondulations in 9%; plaque rupture and thermic lesion in 8%; 22% did not present changes. The collected detritus had 110 +/- microns diameter. Erythrocytes exposed to 30 or 60 sec of ultrasound were found to present crenocytosis, central cavitation, hypochromia, and poikilocytosis; these ones exposed less than 22 sec did not show changes. The fibrinogen levels after the application of ultrasound were 19% lower. Coagulation time did not change with exposure 20 sec long at 20 kHs. The angioplasty guide wires attenuation coefficients were: with the guide wire outside the Miller's catheter, 44%; and with the guide wires inside, 65%. Coronary transluminal angiosonoplasty is a new interventionist technic designed to remodel an obstructive lesion of the coronary arteries, in order to diminish or nullify the obstruction. It's clinic use in the acute myocardial infarction, as a mechanical method to achieve clot's lysis, could be an alternative or a co-helper therapeutics to thrombolysis.