Hemodynamic effects of amrinone in children after cardiac surgery

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Abstract
The hemodynamic effects of amrinone were assessed in seven children following cardiac surgery. Amrinone was administered as a bolus of 1 mg kg−1 body wt., followed by continuous infusion at 10μg kg−1 min−1 for 1h and two stepwise increases to 20 and 40μg kg−1 min−1 for 30 min each. Hemodynamic data were obtained and plasma concentrations of amrinone measured 1 h after the bolus dose and immediately before each increment of the infusion rate. Amrinone levels ranged from 0.7 to 2.3 mgl−1. Administration of amrinone lowered systemic vascular resistance from 20.0±4.3 to 16.5±4.6 mmHgl−1 min−1 m−2 (pp−2, NS) or cardiac index (3.10±0.50 to 3.20±0.40 l min−1 m−2). One additional patient, in whom a higher loading dose was tried in order to achieve a higher plasma concentration, developed systemic hypotension. A correlation was established between the plasma concentrations of amrinone and the percentage decrease in systemic resistance (r=0.70,p<0.05). These results suggest that in children after open heart surgery, amrinone acts primarily as a systemic vasodilator, with questionable inotropic effect. Accordingly, its use should be restricted to children with severe cardiac failure and documented highly elevated afterload.