EFFECTS OF DIGOXIN ON VENTRICULAR ARRHYTH MIAS IN PATIENTS WITH HEART-FAILURE - RELATION TO THE SYMPATHOADRENAL SYSTEM

Ventricular arrhythmias were analysed in 38 patients with Stages I-IIB heart failure from 24-hour Holter monitoring data obtained before and after digoxin therapy by comparing with the concentrations of catecho lamines. There was a direct relationship between the plasma levels of epinephrine and norepinephrine and the severity of ventricular arrhyth mias, as well as between the changes in cumulative catecholamine level s and ventricular arrhythmias during digoxin therapy. Virtually in all cases, the antiarrhythmic effect of the drug was accompanied by lower plasma catecholamine concentrations whereas the levels of norepinephr ine and epinephrine remained nearly unchanged or increased with the te ntatively arrhythmogenic action. The findings may suggest that hyperca techolaminemias are essential in the genesis of ventricular arrhythmia s in heart failure. Cardiac glycosides can heterogeneously affect vent ricular arrhytmias by modifying the activity of the sympathoadrenal sy stem.