Comparison of vasodilator drug prazosin with digoxin in aortic regurgitation.

Abstract

SUMMARY Intravenous administration of the vasodilator sodium nitroprusside has beneficial haemodynamic effects in subjects with severe aortic regurgitation while acute digitalisation can produce unwanted effects associated with an increase in systemic vascular resistance. This study compares the haemodynamic effects of the vasodilator prazosin and digoxin in eight patients with isolated severe aortic regurgitation. Prazosin 5 mg orally resulted in a 12±3 (SE) per cent increase in cardiac index (thermodilution), maintained over four to six hours, while digoxin 075 mg intravenously did not change the cardiac index. Prazosin reduced mean arterial pressure by 9±3 mmHg and systemic vascular resistance by 18±4 per cent while digoxin resulted in a 6±2 per cent increase in the latter. Mean pulmonary capillary wedge pressure fell 3 mmHg with prazosin. In this group of patients with severe aortic regurgitation but without severe cardiac failure, the changes with either drug, studied in doses conventionally used, were small but those with prazosin were directionally more desirable than those resulting from digoxin.This study describes and compares the haemodynamic effects of the orally active vasodilator drug prazosin and digoxin in a group of patients with severe chronic aortic regurgitation.Corrigan," writing in 1832, believed that when digitalis glycosides were administered in the treatment of heart failure resulting from aortic regurgitation, the patients were "always worse".He attributed the harmful effects he observed to bradycardia which "allowed more time for regurgitation". In 1908, Stewart2 predicted harmful effects from digitalis in aortic regurgitation because of a rise in the systemic vascular resistance. Objective evidence of the haemodynamic effects of the digitalis glycosides in the presence of aortic regurgitation is sparse. Kloster and associates3 found that ouabain resulted in a fall in cardiac output in patients with aortic regurgitation without cardiac failure while Hopkins and Taylor4 found that ouabain and acetylstrophanthidin increased the regurgitant fraction in dogs with experimentally *

Captopril in congestive heart failure.

“…In some of our patients valvular replacement could be delayed for more than 2 years. Prophylactic vasodilation might in fact be a reasonable treatment in patients with valvular heart disease without congestive heart failure (Hockings et al, 1980;Greenberg etal., 1982 In congestive heart failure induced by coronary heart disease blood pressure reduction may be dangerous because it reduces myocardial perfusion, and if this induced myocardial ischaemia angina would occur. Despite pronounced reduction of myocardial blood flow, none of the patients with coronary heart disease developed such symptoms.…”

Acute Cardiac Failure: Mechanisms and Review of Therapeutic Efficacy

“…However, the effects of digitalis in patients with aortic regurgitation and severe heart failure are unknown. 24…”