Comparison of vasodilator drug prazosin with digoxin in aortic regurgitation.

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Abstract
I.v. administration of the vasodilator sodium nitroprusside has beneficial hemodynamic effects in subjects with severe aortic regurgitation while acute digitalization can produce unwanted effects associated with an increase in systemic vascular resistance. The hemodynamic effects of the vasodilator prazosin and digoxin are compared in 8 patients with isolated severe aortic regurgitation. Prazosin 5 mg orally resulted in a 12 .+-. 3 (SE) % increase in cardiac index (thermodilution), maintained over 4-6 h; digoxin 0.75 mg i.v. did not change the cardiac index. Prazosin reduced mean arterial pressure by 9 .+-. 3 mm Hg and systemic vascular resistance by 18 .+-. 4 % while digoxin resulted in a 6 .+-. 2% increase in the latter. Mean pulmonary capillary wedge pressure fell 3 mm Hg with prazosin. In patients with severe aortic regurgitation but without severe cardiac failure, the changes with either drug in conventional doses were small but those with prazosin were directionally more desirable than those resulting from digoxin.