Milrinone enhances systolic, but not diastolic function during coronary artery bypass grafting surgery

Purpose: To evaluate the effect of milrinone on diastolic function during coronary artery bypass grafting surgery (CABG). Methods: Fifty patients undergoing CABG were randomized to receive a bolus and infusion of milrinone or placebo before cardiopulmonary bypass (CPB) until skin closure. Hemodynamic and transesophageal echocardiographic measurements of systolic and diastolic function wet e obtained. Pulsed wave Doppler measurements of the early (E wave) and atrial components (A wave) of the transmitral (TMF) and transtricuspid (TTF) flows, and systolic (S wave), diastolic (D wave) and atrial components (Ar) of the pulmonary (PVF) and hepatic venous blood flow (HVF) velocities were performed. Early and atrial components of the mitral (Em and Am waves) and tricuspid annulus velocities (Et and At waves) were assessed by tissue Doppler imaging (TDI). Assessment of diastol c dysfunction was graded from normal to severe using a scale score. Results: Cardiac index and heart rate were higher in the mil-rinone group compared to placebo after the administration of study drug (2.8 +/- 0.6 vs 2.1 +/- 0.5 L(.)min(-1) m(-2)) (P < 0.0001) and (67 +/- 8 vs 60 +/- 12 beats(.)min(-1)) (P < 0.05) respectively. There were no changes in left and right ventricular diastolic dysfunction scores between study groups. Higher PVF S wave, HVF S wave, TTF A wave and At measured by TDI in the mil-rinone group compared with placebo suggested an improvement in ventricular systolic and atrial contraction. Conclusion: Distinct from its effects on systolic function, mil-rinone administered before CPB is not with associated improved biventricular diastolic function in patients undergoing CABG.