HEART-SURGERY - WHAT ARE THE NEUROPSYCHOLOGICAL CONSEQUENCES

The effects of cardiopulmonary bypass (CPB) on neuropsychological functioning were investigated. Sixty-one patients were included in the study; 42 underwent coronary artery bypass grafting (CABG) and 19 valve replacement or a double procedure of valve replacement and CABG (VR). A single standardised CPB protocol was used for all patients. Patients received one of two standard anaesthetics: propofol-fentanyl or isoflurane-fentanyl. A battery of standard neuropsychological tests assessing memory, information processing and visuospatial skills were administered one day pre-operation and 7 days post-operation (day 7). Change in performance from pre-operation to day 7 and whether there were any differences according to operation or anaesthetic administered was investigated. A repeated measures ANOVA was used. There were no significant differences in the effects of the two drugs. There was no strong evidence at a group level of deterioration in neuropsychological functioning at day 7. There were presurgical differences between the two operative groups in visuospatial abilities and speed of performance. The VR group performed more poorly than the CABG group and this persisted at day 7. Despite the preoperative differences, the neuropsychological consequences of CPB did not differ for the two groups. To allow comparability with other studies, the number of subjects deteriorating more than one standard deviation from the preoperative mean was calculated. This indicated that when analysis moved from the group to the individual, there was evidence of deficit. Peri-operative variables were found to be poor predictors of post-operative cognitive functioning in comparison to psychological variables.