A contrastive analysis of release patterns of biochemical markers of brain damage after coronary artery bypass grafting and valve replacement and their association with the neurobehavioral outcome after cardiac surgery

Abstract

Objective: The present study aimed at a comparative analysis of neurobiochemical markers of brain damage and the neurobehavioral outcome in patients undergoing either valve replacement (VR) or isolated coronary artery bypass surgery (CABG). In order to control for well known risk factors both samples were strictly matched according to age, sex and preoperative neuropsychological performance.

Methods: We analysed neurone-specific enolase (NSE) and protein S-100B (S-100B) concentrations in serial venous blood samples taken preoperatively and 1, 6, 20 and 30 h postoperatively in 36 patients undergoing VR (N = 18) or isolated CABG surgery (N = 18). Mini Mental State Examination (MMS) was performed preoperatively, 3 and 7 days after surgery and 0.5 years later. Neuropsychiatric assessments were based on the diagnosis of postoperative delirium according to DMS-IIIR criteria and the Brief Psychiatric and the Delirium Rating Scale.

Results: VR and CABG patients, respectively, showed an increase of both S-100B (exact two-tailed Wilcoxon signed ranks test: P = 0.0001) and NSE (P = 0.0001) concentrations followed by a decrease during the next 30 h. Whereas S-100B values did not differ between patients groups subjects undergoing VR surgery exhibited higher NSE values during the postoperative course. Furthermore, VR patients showed a higher decline in cognitive performance which was also detectable 0.5 years after surgery. We found a weak association between the degree of individual postoperative decline of cognitive performance and S-100B area under curve values.

Conclusions: Our data indicate that--apart from patients' age and preoperative neuropsychological performance--type of surgery remains a risk factor for postoperative neurobehavioral disorders. The different vulnerability of neurobehavioral disorders might be mirrored in different postoperative release patterns of NSE. We assume that both, NSE release and neurobehavioral disorders might be caused by a higher amount of intraoperative cerebral embolic events in VR patients.