[Effect of electric stimulation rate on the indicators of systolic and diastolic activity of the left ventricle].

The interrelationship of the indices of the systolic and diastolic myocardial activity with reference to the cardiac contractions rate was studied in acute experiments in isolated feline hearts. The study had demonstrated that moderate tachycardia (a 30% increase of the cardiac contractions rate) produced a beneficial inotropic effect, and increased the diastolic compliance of the myocardium. Severe tachycardia (a 80--100% increase of the contractions rate) produced a negative inotropic effect decreasing the myocardial compliance. Proceeding from the obtained results a conclusion is drawn that the cardiac contractions rate is an important factor in the regulation of not only the systolic, but also the diastolic myocardial activity.