Suppression of the renin-angiotensin system by intravenous digoxin in chronic congestive heart failure.

Recent studies have demonstrated that therapy with digitalis preparations may be of inconsistent benefit in the treatment of chronic congestive heart failure. One explanation may be a varying effect on vasoconstrictor hormones, as digoxin has been shown to suppress plasma renin activity in normal and hypertensive persons. Therefore, the effect of short-term digoxin administration on plasma renin activity and plasma aldosterone in six patients with compensated, severe, chronic congestive heart failure was evaluated. Intravenous administration of digoxin (0.50 mg) resulted in a reduction of plasma renin activity from 4.3 +/- 0.9 to 2.0 +/- 0.9 ng/ml per hour and plasma aldosterone from 34 +/- 16 to 14 +/- 6 ng/dl (both p less than 0.05). Maximal response occurred at three hours after administration, with return to baseline by seven hours. Therefore, evaluation of the role of digitalis in chronic heart failure requires consideration of its direct or indirect effect on angiotensin-mediated vasoconstriction and aldosterone-mediated sodium retention, as well as other neurohormonal mechanisms of vasoconstriction.