[New anti-arrhythmia drug. III. Comparative studies of the effects of N-propionylprocainamide, procainamide and N-acetylprocainamide on hemodynamics and cardiac blood flow]

Abstract

Procainamide (PA) often applied in cases of ventricular arrhythmias causes numerous cardiac and extracardiac undesirable symptoms. Its active metabolite, N-acetylprocainamide (NAPA; Acecainide) is known to affect less noxiously the ventriculo-atrial conduction and the intraventricular++ conduction, and it does not impair contractility of the heart muscle. Many drugs with proven antiarrhythmic activity cannot be used in clinical practice because of disadvantageous effects on the function of the left ventricle and on the coronary blood flow, particularly in patients with the recent myocardial infraction. It seems that another acyl derivative of procainamide with potential antiarrhythmic activity, N-propionylprocainamide (NPPA) may be less harmful than PA, and NAPA. Effects of milimolarly equivalent doses of NPPA, NAPA and PA on the cardiac output and the stroke volume index, as well as on the coronary blood flow were investigated in rabbits by the radioisotope method. The obtained results were subjected to statistical analysis. NPPA was found to display no depressive action on the function of the left ventricle. Moreover, it was found to improve the coronary blood flow in rabbits.