The effects of digitalis on systolic time intervals of the left ventricle in the patients with artificial pacemaker; Relation between effect of digitalis and clinical findings

Abstract

Twelve patients who had been implanted artificial pacemaker for the treatment of bradycardia due to atrioventricular block, S.S.S. and atrial fibrillation were studied to determine the respone to digitalis in the resting position using mechanocardiogram. The ejection time, isometric contraction time, preejection period and Q-S_II interval shortened following digitalis administration. There was not found significant relationship between the changes in ejection time and preejection period. The degree of shortening of ejection time was more remarkable in the elder patient and/or with diastolic hypertension, while the degree of shortening of preejection period was more remarkable in the catient with S.S.S and atrial fibrillation and/or normotension.
It is considered that the results obtained in this study were produced by complicated consequences including an increased force and velocity of the cardiac contraction, increased peripheral arterial resistance and increased cardiac output due to digitalis, and probably underlying disease.