Vasodilators as first-line therapy for congestive heart failure: A comparative hemodynamic study of hydralazine, digoxin, and their combination

Abstract

Although digitalis and vasodilators both enhance cardiac performance in patients with congestive heart failure, their relative efficacy is unknown. Accordingly, the acute hemodynamic effects of intravenous hydraiazine (0.15 mg/kg), digoxin (1.0 mg), and the hydralazine-digoxin combination were evaluated in 14 normotensive heart failure patients at sitting rest, nine of whom were also studied during submaximal upright bicycle exercise. Hemodynamic responses at rest and exercise were similar. Cardiac output and stroke volume rose with both agents, the increase in cardiac output with hydralazine exceeding that with digoxin at rest. Left and right ventricular filling pressures declined equally. Systemic arterial mean pressure and total systemic vascular resistance fell with hydralazine, while, with digoxin, systemic arterial mean pressure increased and total systemic vascular resistance was unchanged. The hydralazine-digoxin combination produced increases in cardiac output and stroke volume that were greater than with either drug alone, and that equalled the sum of the drugs' individual effects; reductions in ventricular filling pressures were similar to the single-drug interventions. Thus, hydralazine is at least as effective as digoxin in improving cardiac function over the short term. Vasodilators may constitute an acceptable alternative to digitalis as initial therapy for congestive heart faillure, except where a reduction in systemic arterial pressure is potentially deleterious. Use of combined treatment produces greater increases in cardiac output than with either drug alone, but requires risking the toxicities of two agents.