[Effect of the anti-arrhythmia compounds etmozin and ethacizine on the contractile activity of myocardial preparations from heart defect patients].

Changes in contraction amplitudes, contraction peak time and relaxation time were evaluated at 50% and 80% of contraction peak, with adrenaline or strophanthin acting on the myocardium pretreated with antiarrhythmic substances, using atrial specimens from patients with acquired heart diseases and septal defects. Etmozin and ethacizine were shown to have a negative inotropic effect, reducing contraction intensity by about 50%. Adrenaline and strophanthin are capable of restoring myocardial contractility in the presence of antiarrhythmic effects without actually inducing spontaneous auto-arrhythmic activity. Causes of the recovery of myocardial mechanical activity, effectuated by adrenaline or strophanthin in the presence of antiarrhythmic agents are discussed. It is suggested that a combination of effective antiarrhythmic properties and negative inotropic effect of phenothiazines is significant for cases of arrhythmias with and without signs of heart failure.