Characteristic Changes in Cerebral Perfusion During On-Pump and Off-Pump Coronary Artery Surgery

Objective: We investigated the cerebral perfusion status during on-pump or off-pump coronary artery bypass grafting (CABG).

Methods: We monitored somatosensory evoked potential (SEP) and regional cerebral oxygen saturation (rSO2) as parameters of cerebral perfusion in an on-pump group (n=10) and an off-pump group (n=16). The percent changes from control values were calculated before, during, and after aortic clamping, and after weaning from cardiopulmonary bypass, in the on-pump group. In the off-pump group, these were calculated before, during, and after heart displacement for distal anastomosis.

Results: In the on-pump group, the amplitudes of the SEP were significantly enhanced during and after aortic cross-clamping and were associated with a significant decrease in rSO2. Latency was prolonged immediately after aortic cross-clamping, but was shortened afterwards. There was little change in these parameters throughout the operation, in the off-pump group.

Conclusions: Cerebral perfusion remains stable during off-pump CABG. The etiology of a simultaneous increase in SEP amplitude and decrease in rSO2 during the rewarming period in the on-pump group requires further investigation.