BACKGROUND: It has been widely believed that pulsatile flow was better than nonpulsatile flow. However it remains uncertain whether pulsatile perfusion has shown substantive clinical improvement compared to standard, nonpulsatile perfusion. The purpose of this study was to compare nonpulsatile perfusion with pulsatile perfusion on hemodynamic and renal function during and after cardiopulmonary bypass (CPB) in the patients undergoing coronary artery bypass grafting (CABG). METHODS: Twenty patients undergoing CABG were divided into two groups, nonpulsatile perfusion group (NP) and pulsatile perfusion group (PP). Hemodynamic data was measured at preinduction, postinduction, immediately after aorta cross clamping (ACC on), and 60 minutes after the start of CPB (CPB 60'). Hemodynamic variables included mean arterial pressure (MAP), peripheral vascular resistance (PVR), plasma catecholamine (epinephrine, norepinephrine), and dosage of the vasodilator (sodium nitroprusside). Renal parameters were urine output, and serum BUN and creatinine. They were measured at preCPB, during CPB, postCPB, and POD 1. RESULTS: MAP was significantly higher in NP at CPB 60'. At CPB 60, PVR returned to preinduction level in NP, but was still decreased in PP. The dosage of vasodilator (sodium nitroprusside) infusionwas significantly higher in NP than in PP. In both groups, plasma epinephrines were increased significantly during CPB but there was no difference between the groups. Plasma norepinephrine was significantly higher in NP than in PP during CPB. At postCPB, urine output was higher than preCPB only in PP. At POD 1, serum BUN increased to the preCPB level in NP but was still decreased in PP. After CPB, serum creatinine was decreased significantly in PP. There was no significant difference in renal parameters between both groups. Conclusion: It was suggested that pulsatile perfusion, compared with nonpulsatile perfusion, can attenuate hemodynamic changes by decreasing release of plasma norepinephrine, peripheral vascular resistance, mean arterial pressure and dosage of vasodilator during cardiopulmonary bypass. Pulsatile perfusion didn't show substantive clinical difference of renal outcome in patients without preoperative renal dysfunction.