[Use of paired impulses and automatic depressing stimulation during sinus tachycardia systole in experimental acute myocardial ischemia].

In 102 dog experiments, the effect of a twin stimulator and a device of original design, providing automated pace rarefication, on the heart's contractility and hemodynamics, coronary flow and myocardial electric activity was examined in conditions of acute ischemia. Rarefying stimulation was found to have the best effect in cases of basic tachycardia and accompanying heart failure, which is related to the postextrasystolic potentiation effect. The stimulation in the presence of myocardial hyperfunction or an excessive induced rarefication of heart rhythm may result in negative electrographic and hemodynamic changes, the latter being systemic as well as intracardiac. The advantages of automated stimulation are in that it provides stability of rhythm rarefication rate so that continuous control of the pace-making is rendered unnecessary, and rules out the possibility of an impulse falling to the vulnerable period.