Milrinone, not epinephrine, improves left ventricular compliance after cardiopulmonary bypass

Objective: To compare the effects of milrinone versus epinephrine administered after cardiopulmonary bypass (CPB) on left ventricular compliance, Design: Prospective and randomized. Setting: University-affiliate hospital. Participants: Twenty consenting adult patients. Interventions: Patients undergoing aortocoronary bypass surgery were randomized to receive 50 mu g/kg of milrinone [group M; n = 10) or 0.03 mu g/kg/min of epinephrine (group E; n = 10) shortly after separation from CPB, Left ventricular compliance was assessed by observing changes in left ventricular end-diastolic area (LVEDA) in the short-axis view with transesophageal echocardiography, while maintaining a constant left atrial pressure. Measurements were performed (1) before CPB, (2) after separation from CPB, and (3) after either milrinone or epinephrine. Measurements and Main Results: Baseline LVEDA decreased by 20% after CPB in the milrinone group (from 16.6 +/- 3.1 cm(2) to 14.3 +/- 2.4 cm(2); p < 0.05) and by 22% in the epinephrine group (from 19.4 +/- 4.1 cm(2) to 17.2 +/- 3.8 cm(2); p < 0.05), LVEDA increased by 15% after milrinone (from 14.3 +/- 2.4 cm(2) to 15.6 +/- 2.8 cm(2); p < 0.05) but remained unchanged after epinephrine (from 17.2+/-3.8 cm(2) to 17.1 +/- 4.2 cm(2); p = ns), Conclusions: Left ventricular compliance was decreased after CPB, The administration of milrinone, but not epinephrine, was associated with a partial return to prebypass values. The exact mechanism of action remains to be determined. Copyright (C) 2000 by W.B. Saunders Company.