Electrocardiographic diagnosis of experimentally-induced myocardial infarction during cardiac electrostimulation

The sequential ECG changes were studied by the Sodi-Pallares' method in 10 dogs before and after experimentally induced myocardial infarction of the left ventricle during right and left artificial stimulation. Right ventricular endocardial stimulation produced patterns of left bundle branch block in 9 dogs and of right bundle branch block in one, while left ventricular stimulation caused right bundle branche block patterns in 9 animals. Records during right ventricular stimulation after myocardial infarction showed in the peripheral leads myocardial necrosis only in two animals, while in the epicardial leads necrosis was certain in 2 animals (Q wave) probable in 6 (S-T segment elevation) and suggestive in 2 (T wave negativity). Myocardial necrosis during left ventricular stimulation was evident in the peripheral leads in 2 animals, probable in 6 and suggestive in one. The experimental data suggest that myocardial necrosis can be diagnosed in some cases during right and left ventricular artificial stimulation.