CLINICAL AND HEMODYNAMIC-EFFECTS OF MILRINONE IN THE TREATMENT OF LOW CARDIAC-OUTPUT AFTER CARDIAC-SURGERY

We have studied the haemodynamic effects of i.v. milrinone, a new phosphodiesterase inhibitor, in patients with low cardiac output after cardiac surgery. Thirty-five patients with a cardiac index (Cl) < 2.5 litre min-1 m-2 and a pulmonary capillary wedge pressure (PCWP) > 8 mm Hg were given a loading dose of milrinone 50-mu-g kg-1 followed by an infusion at one of three rates: 0.375-mu-g kg-1 min-1, 0.5-mu-g kg-1 min-1 or 0.75-mu-g kg-1 min-1 for 12 h. After 1 h there were increases in Cl (35 %) (P < 0.001), heart rate (13 %) (P < 0.01) and stroke volume index (19 %) (P < 0.005). There were decreases in mean arterial pressure (12 %) (P < 0.01), systemic vascular resistance (35 %) (P < 0.001) and PCWP (24 %) (P < 0.05). Pulmonary vascular resistance was unchanged or reduced and left ventricular stroke work index was unchanged or increased. The haemodynamic improvements were sustained throughout the infusion period. Milrinone was tolerated well: three patients developed tachycardia > 125 beat min-1, one patient developed atrial fibrillation and one patient had a short run of atrial bigemini. We conclude that milrinone is a useful agent in the treatment of patients with a reduced cardiac output after cardiac surgery.