[Ventricular fibrillation in acute phase of myocardial infarct. 1. Relationship between the development of ventricular fibrillation in myocardial infarct and previous rhythm disorders].

The author analyses the results of experimental studies in dogs and cats, that included a continuous recording of ECG, electrogram and monophase cardiac potentials during 1 hour following coronary artery ligation. The ligation caused bradycardia, but no correlation was found between the degree of bradycardia and the development of extrasystole and ventricular fibrillation. Extrasystole developed in 100% of the experiments in which the coronary artery ligation resulted in ventricular fibrillation, and in 66% and 87% of those without this complication, conducted in dogs and cats respectively. The rate of extrasystole proved important for the prognosis of fibrillation. The number of extrasystoli noted during the mean time of the development of fibrillation was 5 times higher in the experiments with ventricular fibrillation than in those without fibrillation. In the experiments with fibrillation the extrasystoli tended to occur earlier within the cardiac cycle. Of the total number of extrasystoli, grouped extrasystoli comprised 89% in the experiments with ventricular fibrillation, and 21%--in those without fibrillation. Ventricular tachystystole was noted in 50% of the experiments with fibrillation and in 17% of those without this complication. In the experiments complicated by fibrillation the period of ventricular tachysystole was characterized by a gradual shortening of the cardiac cycles.