BACKGROUND: Milrinone is a bipyridine phosphodiesterase III inhibitor that exerts both positive inotropic and direct vasodilatory effects. The efficacy and safety of intravenous milrinone in heart failure has been evaluated in a number of clinical studies. In addition, performance of the right ventricle is improved primarily in reduced right ventricular afterload, and pulmonary vascular resistence as milrinone produces minimal inotropic effects on the right ventricle. Most clinical studies have been performed in left ventricular failure patients. Therefore, we investigated whether intravenous milrinone improves the hemodynamics in patients with pulmonary hypertension due to valvular heart disease. METHODS: This study included 33 patients undergoing a valvular replacement with pulmonary hypertension (mean pulmonary artery pressure > or = 30 mmHg after induction). Patients were randomly divided into two groups, normal saline group (N) and milrinone group (M). In group N, normal saline was infused. In group M, a single intravenous bolus of milrinone (50mug/kg body weight) was injected over 10 min. Hemodynamic data were measured at preinjection, 5, 10, and 20 min after injection. RESULTS: There was no significant difference in systemic mean arterial pressure and central venous pressure between both groups. In group M, systemic vascular resistance was reduced at 5 min after injection and cardiac index was improved at 10 min after injection. There was no significant difference in pulmonary mean arterial pressure and vascular resistance between both groups. CONCLUSIONS: Milrinone had no effect on pulmonary artery pressure and pulmonary vascular resistance in patients with pulmonary hypertension due to valvular heart disease. However, it increased cardiac index and decreased systemic vascular resistance.