An amrinone bolus prior to weaning from cardiopulmonary bypass improves cardiac function in mitral valve surgery patients.

This double-blind, randomized study was performed to assess the effectiveness of a single bolus dose of 2 mg/kg of amrinone given during cardiopulmonary bypass (CPB) to patients undergoing mitral valve surgery. Outcome variables were hemodynamic function and the number and amount of vasopressors or inotropes required to wean from CPB. In amrinone-treated patients, cardiac index (CI) increased significantly by 48 +/- 14% following CPB (T3) versus 10 +/- 10% for placebo-treated patients (P = 0.029). Similarly, on arrival in the intensive care unit (T4), CI was increased by 52 +/- 20% in amrinone patients versus 8 +/- 8% for placebo patients (P = 0.04). There was a corresponding decrease in systemic vascular resistance index of 47 +/- 6% at T3 in the amrinone patients versus 10 +/- 14% in placebo patients (P = 0.001), and a decrease of 30 +/- 7% at T4 versus an increase of 10 +/- 22% for the placebo patients (P = 0.036). There was no difference in other measured hemodynamic variables. While on CPB, mean arterial pressure at 5 minutes following administration of the study drug was decreased in amrinone patients by 20 +/- 4% versus 4 +/- 3% in placebo patients (P = 0.005), but was no different at 10 and 15 minutes. There were no statistically significant differences in the number of patients who required supplemental inotropes or vasopressors either during CPB, following separation from CPB, or upon arrival in the ICU. Thus, amrinone improved CI without changing pulmonary vascular resistance or the requirement for supplemental inotropes or vasopressors in patients undergoing elective mitral valve surgery.