Off-pump coronary artery bypass grafting (OPCAB) on the beating heart causes hemodynamic compromise during displacement of the heart for graft anastomosis. To overcome hemodynamic unstability, volume loading, Trendelenburg position, inotropic and vasodilator supports etc. are selected as usual. This study was designed to compare the hemodynamic effects of milrinone and dopamine on OPCAB anesthesia.

Twenty patients (13 men, 7 women; mean age 63.4 ± 18.2 years old) who underwent OPCAB were enrolled in this study. The patients were randomly placed in a dopamine group (n = 10) and in a milrinone group (n = 10). Basic doses of each drug was administered during left anterior descending artery (LAD), posterior descending arterty (PDA), and left circumflex artery territory (LCX) anastomosis. Hemodynamic variables such as; heart rate (HR), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), cardiac index (CI), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR), central venous pressure (CVP), and pulmonary capillary wedge pressure (PCWP) were collected before mechanical stabilization (T1), during anastomosis (T2), and 5 minutes after anastomosis (T3) of LAD and LCX in each patient.

During LAD anastomosis, HR in the D group increased significantly at T2 (12.6%(upword arrow)) and T3 (9.8%(upword arrow)) but didn't show significant changes in the M group. CI in the M group showed significant increase at T3 (21.7%(upword arrow) compared to T3 and 18.0%(upword arrow) compared to the D group). During LCX anastomosis, HR didn't show significant changes in the M group, MAP in the D group showed significant decrease (19.3%) at T2 but it was insignificant in the M group. MPAP and PVR showed significant increase at T2 in the D group compared to T1 and T2 in the M group. PCWP showed similar changes of PVR during LCX anastomosis

Hemodynamic changes during OPCAB are more remarkable during LCX anastomosis than LAD anastomosis. These changes can be successfully relieved by inotropic supports with continuos milrinone infusion during anastomosis.