Neuropsychological changes after cardiopulmonary bypass for coronary artery bypass grafting

An alarming incidence (1% to 83%) of neuropsychological dysfunction has been reported after operations using cardiopulmonary bypass (CPB). The present clinical study re-evaluates these complications with current CPB technology in a strictly selected low-risk group of coronary artery bypass (CABG) patients.

76 CABG patients, without history of stroke or internal carotid artery stenosis, were examined before, 5 days after, and 2 months after surgery. A neuropsychological test battery was employed according to the "Statement of Consensus on Assessment of Neurobehavioral Outcomes after Cardiac Surgery". Tests include the Block Design Test (problem-solving strategies, recognition and analysis of forms), the Trail Making Test (cognitive achievement at speed), and the Digit Span Test (short-term memory and memory of figures).

Both postoperative test scores were not significantly decreased as compared to preoperative values. In contrast, neuron specific enolase (NSE) and S100 b protein, biochemical markers of cerebral injury, increased markedly during and immediately after surgery (NSE preop.: 7.07 +/- 2.40 ng/ml, 1 h postop.: 13.64 +/- 4.50 ng/ml, p < 0.001; S100 b preop.: 0.04 +/- 0.07 ng/ml, after crossclamp: 0.90 +/- 0.69 ng/ml, p < 0.001). One patient displayed postoperative transitional syndrome, another patient suffered from transitory paresis and hypesthesia of the left arm, which disappeared during hospital stay.

Biochemical markers demonstrate significant postoperative cerebral injury during and immediately after CPB. However, CPB for CABG does not lead to marked impairment of neuropsychological scores, and clinically relevant neurological findings were observed in one patient only.