Objective: Studies on the effects of digoxin in patients with right ventricular failure and normal left ventricular function have not been performed. We evaluated the short-term effects of digoxin administration in patients with primary pulmonary hypertension on hemodynamics, neurohormones, and baroreceptor responsiveness.
Design: This was a prospective study with patients serving as their own controls.
Setting: University Hospital Intensive Care Unit with central monitoring.
Patients: Seventeen patients with primary pulmonary hypertension and symptomatic heart failure were enrolled.
Interventions: Following baseline hemodynamics, neurohormonal samples were drawn and the heart rate response to change in blood pressure following a challenge of phenylephrine and nitroprusside were recorded. One mg of intravenous digoxin was given and the measurements repeated after 2 hours.
Results: Following digoxin there was a significant increase in cardiac output (3.49±1.2 to 3.81±1.2 L/min., p=0.028), a significant fall in norepinephrine (680±89 to 580±85 pg/ml, p=.013), and a significant increase in atrial natriuretic peptide (311±44 to 421±9 pg/ml, p=0.01). All of the patients had changes in heart rate and blood pressure following phenylephrine and nitroprusside challenge, but there was no significant difference in the change in heart rate response to change in blood pressure when rechallenged after digoxin treatment.
Conclusion: Digoxin produces a modest increase in cardiac output in patients with pulmonary hypertension and right ventricular failure, as well as a significant reduction in circulating norepinephrine. No detectable effects of digoxin on baroreceptor responsiveness were apparent. The use of digoxin in pulmonary hypertension is warranted.