EFFECT OF BOLUS MILRINONE ON HEMODYNAMIC VARIABLES AND PULMONARY VASCULAR-RESISTANCE IN PATIENTS WITH SEVERE LEFT-VENTRICULAR DYSFUNCTION -A RAPID TEST FOR REVERSIBILITY OF PULMONARY-HYPERTENSION

Objectives. To examine the feasibility of using milrinone to test pulm onary vascular reactivity in patients before heart transplantation, we tested the hypothesis that milrinone would lower pulmonary vascular r esistance (PVR) in patients with severe heart failure, Background Fixe d pulmonary hypertension is a risk factor for right heart failure and death after orthotopic heart transplantation, Sodium nitroprusside, th e agent used most commonly to test for reversibility of pulmonary hype rtension before transplantation, requires dose titration and is freque ntly limited by hypotension, Milrinone is an intravenously active phos phodiesterase inhibitor that acts rapidly and exerts both positive ino tropic and direct vasodilator effects in patients with heart failure, The ability of milrinone to lower PVR in patients with heart failure h as not been tested, Methods. In 27 patients with New York Heart Associ ation functional class III or TV heart failure referred for heart tran splantation with a PVR greater than or equal to 200 dynes-s-cm(-5), we measured the hemodynamic response to a single intravenous bolus of mi lrinone (50 mu g/kg body weight) infused over 1 min.Results. Milrinone decreased PVR in all patients, The effect was maximal 5 to 10 min aft er the bolus and persisted for at least 20 min, The reduction in PVR a t 5 min ([mean +/- SEM] 31 +/- 4%) was associated with a 42 +/- 4% inc rease in cardiac output and decreases of 12 +/- 4% and 16 +/- 5% in me an pulmonary artery and pulmonary artery wedge pressures, respectively , but no change in transpulmonary pressure gradient, Milrinone had no effect on heart rate or systemic arterial pressure, The magnitude of t he decrease in PVR correlated inversely with the milrinone-induced inc rease in cardiac output. Conclusions. Bolus milrinone consistently dec reases PVR in patients with pulmonary hypertension secondary to severe heart failure, This effect is rapid in onset and well tolerated, even by patients with low systemic arterial pressure, An intravenous bolus of milrinone can be used to test for the reversibility of pulmonary h ypertension in patients with heart failure undergoing evaluation for h eart transplantation. (C) 1996 by the American College of Cardiology