Influence of Digitalization on the Contribution of Atrial Systole to the Cardiac Dynamics at a Fixed Ventricular Rate

THE hemodynamic consequences of acute digitalization in man have been reported in a few studies with controversial results.It has been stated that digitalis has little or no effect on the cardiovascular events in the ab- sence of manifestations of heart failurel-' while it significantly improves cardiac function in the failing heart.'2 This paper describes the effect of acute digitalization on the cardiovascular dynamics in patients with complete heart block with a fixed ventricular rate and the effect of digitalization on the contribution of atrial systole to ventricular filling at a fixed ventricular rate. Material and MethodsSix patients with complete atrioventricular block resulting from coronary disease were studied.This diagnosis was established by the presence of a history of myocardial infarction in two cases.In the remaining four cases this diagnosis was suspected on the basis of onset of heart block above age 60 and by the absence of any other etiologic factor that could explain the presence of heart block.The average age of the patients studied was 70.3 years.All patients had the wires of a permanent cardiac pacemaker* (Chardack-Greatbatch fixed rate) implanted in the free wall of the left ventricle for treatment of heart block.The pacemaker rate was fixed within the range of 70 to 75 impulses per minute.The studies were performed 3 to 12 months after operation and at this time the patients had no