Investigation of factors relating to neuropsychological change following cardiac surgery

BACKGROUND: An analysis of neuropsychological impairment following cardiopulmonary bypass was performed in 55 patients undergoing elective coronary artery bypass grafting. METHODS: Neurocognitive function was measured preoperatively using the MicroCog: Assessment of Cognitive Functioning computer-based testing tool. Testing was repeated in the postoperative period immediately prior to discharge from hospital. Analysis of significant score decline was performed using the standardised regression-based technique. A patient was classified as overall impaired when > or = 20% of test scores were significantly impaired. The proposed marker of neurological damage S-100beta was also used. Prothrombin Fragment 1+2 (F1+2) was measured as a marker of thrombin development to test the hypothesis that excessive haemostatic activation may lead to thromboembolic damage to the brain. RESULTS AND CONCLUSIONS: 32.7% of patients were classified as significantly impaired. No relationship was detected between F1+2 and any neuropsychological test score; however, the study was limited due to small sample size. F1+2 levels were higher in patients undergoing prolonged bypass times. Neuropsychological decline was significantly correlated with patient age, suggesting a degree of caution is warranted when operating on an elderly cohort. An unexpected relationship was detected between higher heparin concentrations and increased risk of neuropsychological impairment; however, this requires re-evaluation.