Irregular Ventricular Tachycardia as a Mechanism of Stabilization of Mechanoelectrical Processes in Canine Heart under Conditions of Antiorthostatic Hypokinesia

Resumo

We studied electrophysiological mechanisms of ventricular arrhythmias in dogs (n=7) under conditions of antiorthostatic hypokinesia (head-down tilt 45°). Abnormal transmural heterogeneity of repolarization in the base and apex of the left ventricle and increased dispersion of myocardial repolarization were revealed. By minute 30 of antiorthostatic hypokinesia, an increase in the duration of repolarization was revealed after a period of ventricular arrhythmia in all segments and regions of heart ventricles, which was accompanied by impairment of the pumping function of the heart. A hypothesis on the physiological role of ventricular tachycardia as a mechanism of electromechanical homeostatic stabilization in the heart was proposed. The obtained results suggest that under conditions of antiorthostatic hypokinesia, canine heart after a paroxysm of irregular ventricular tachycardia becomes more resistant to arrhythmia.