Neuromonitoring and Neurocognitive Outcome in Off-pump Versus Conventional Coronary Bypass Operation

Background: Cardiopulmonary bypass seems to be a major cause for both intraoperative microemboli and cerebral hypoperfusion. This study investigates high intensive transient signals (HITS) in transcranial Doppler ultrasound (TCD) and serum levels of the neurobiochemical marker protein S-100 in patients who underwent coronary artery bypass operation without cardiopulmonary bypass (off-pump CABG) in comparison with the conventional procedure using cardiopulmonary bypass (CPB). The results are related to the neuropsychologic outcome in both surgical groups.

Methods: Forty patients were randomized in 2 groups (20 conventional and 20 off-pump CABG). Neurocognitive status was assessed preoperatively and postoperatively. Venous serum levels of S-100 protein were measured before and after coronary operation, HITS were measured in the middle cerebral artery during the operation.

Results: The median value of HITS was 394.5 (0 to 2217) in the conventional versus 11 (0 to 50) in the off-pump group, p less than 0.0001. Postoperative S-100 serum levels were: 3.76 (0.13 to 11.2) microg/L (conventional) versus 0.13 (0.04 to 1.01) microg/L (off-pump), p less than 0.0001. Postoperative cognitive testing showed significantly different results with a postoperative impairment of 90% of the patients in the conventional group versus no impairment in the off-pump group.

Conclusions: Cognitive impairment seems to be strongly associated to CPB and the occurrence of micro-emboli. The off-pump technique appears to be promising in order to eliminate the source of these neuropyschologic impairments following CABG operation.