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Suppression of the renin-angiotensin system by intravenous digoxin in chronic congestive heart failure
Insights
Digoxin reduces key hormones involved in vasoconstriction and sodium retention in patients with severe chronic heart failure. This finding is crucial for understanding digitalis therapy
Area of Science:
- Cardiology
- Pharmacology
Background:
- Digitalis therapy for chronic congestive heart failure shows inconsistent benefits.
- This inconsistency may stem from variable effects on vasoconstrictor hormones.
- Digoxin is known to suppress plasma renin activity in certain populations.
Purpose of the Study:
- To evaluate the short-term effects of digoxin on plasma renin activity and plasma aldosterone.
- To assess these effects in patients with compensated, severe, chronic congestive heart failure.
Main Methods:
- Six patients with severe chronic congestive heart failure were administered intravenous digoxin (0.50 mg).
- Plasma renin activity and plasma aldosterone levels were measured before and after administration.
Main Results:
- Digoxin significantly reduced plasma renin activity (from 4.3 to 2.0 ng/ml/hr) and plasma aldosterone (from 34 to 14 ng/dl).
- These reductions were statistically significant (p < 0.05) and peaked at three hours post-administration.
- Hormone levels returned to baseline by seven hours after digoxin administration.
Conclusions:
- Short-term digoxin administration effectively suppresses plasma renin activity and plasma aldosterone in severe chronic heart failure.
- These effects on angiotensin-mediated vasoconstriction and aldosterone-mediated sodium retention should be considered when evaluating digitalis therapy.
- Further research into digitalis's neurohormonal mechanisms in heart failure is warranted.
Abstract:
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.