Effect of Water-Soluble Echinochrome Analog on Arrhythmia Severity in Experimental Model of Acute Myocardial Ischemia.

The effects of therapeutic or preventive-therapeutic administration of water-soluble echinochrome analog U-441 on arrhythmia severity assessed by a set of myocardial spatio-temporal depolarization and repolarization parameters were examined on the model of acute myocardial ischemia in cats. Coronary occlusion increased activation time and decreased repolarization time in the ischemic zone; in addition, it increased both global and borderline (local) dispersions of repolarization. The linear regression model showed that only activation time values measured at the initial state and at termination of occlusion were associated with total arrhythmia score during ischemia (regression coefficient β=0.

[Changes of repolarization properties of the right ventricle in hypertensive left ventricular hypertrophy].

Repolarization properties of left ventricular (LV) myocardium change during its hypertrophy of various genesis. Aim of this work was to study repolarization of epicardial surface of the right ventricle (RV) in experimental model of LV hypertrophy caused by renovascular hypertension in rats. We registered 32 unipolar electrograms on the surface of cardiac ventricles and calculated duration of activation recovery intervals for assessment of repolarization.

Repolarization of ventricular myocardium in atrioventricular electrical stimulation of the heart in dogs.

The duration of ventricular myocardium excitation increases during atrioventricular stimulation of dog heart and the sequence of depolarization of the right and left ventricles is desynchronized. Significant shortening of the activation-recovery interval in the intramural and subendocardial layers of the left ventricular base leads to modification of the repolarization sequence in this area and to an increase of total dispersion of activation-recovery intervals in the cardiac ventricles, as a result of which repolarization sequence starts partially repeating the depolarization sequence.

Time correlation between initial activation of ventricular myocardium and cardiac electric potentials on body surface in dogs.

Parameters of cardioelectric field on body surface and propagation of excitation in ventricular myocardium during initial activation were studied using multichannel synchronous electrocardiotopography. It was shown that inversion of areas of negative and positive potentials of cardioelectric field on body surface at the moment of excitation propagation to the epicardium reflected changes in the main direction of excitation wavefront in ventricles.