[Experimental study of laser ablation on lethal arrhythmias--features and effectiveness of epicardial mapping]

To find the exact location of the ventricular arrhythmogenic myocardium, we mapped activation times of local epicardial electrograms (ATLE: 16 bipolar electrodes, 2 x 2 cm2) aided by an on-line computer and guided laser ablation of lethal ventricular arrhythmias induced by aconitine. Thirty-six tests involved 12 dog hearts. Nd:YAG laser application converted ventricular tachycardias and fibrillation to sinus rhythm in all tests. Epicardial mapping results showed: Taking ECG lead II as reference, the differences among all ATLE were within 15ms, and there was no obvious conduct slow zone before drugging and after resuming sinus rhythm, even though 298 +/- 157 mm2 photocoagulation areas (n = 36) resulted from laser irradiation; During VT, the majority of ATLE were preexcited from 90 to 30 ms, and more than one breakthrough point existed, with one predominating; ATLE changed significantly after laser. The ectopic foci were located exactly by using ATLE for laser treatment.