Short-term and long-term neuropsychological consequences of cardiac surgery with extracorporeal circulation

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Abstract
OBJECTIVE: Cognitive dysfunction after extracorporeal circulation is amajor continuing problem in modern cardiac surgery. We designed thisprospective study to update the incidence of postoperativeneuropsychological changes after routine cardiopulmonary bypass (CPB) andto identify perioperative variables associated with these complications.METHODS: We assessed the patients with a comprehensive neuropsychologicaltest battery 1 day before, 7 days after (n = 109) and 6 months after (n =91) cardiopulmonary bypass. We used patients undergoing major vascular orthoracic surgery as a surgical control group (n = 20). RESULTS: Repeatedmeasures multivariate analysis of variance (using surgical group as abetween-subjects factor) on the group data revealed significant changesearly after surgery compared with the preoperative performance (P = 0.001).The early changes are characterized by a significant decrease of visualattention and verbal memory performance (univariate F-tests, always P <0.05). Cardiac patients showing cognitive impairment after cardiac surgeryhad lower preoperative ejection fractions (P = 0.014) and a morecomplicated medical history (P = 0.046). At 6-month follow-up, the patientsperformed significantly better than before surgery (P < 0.001). CPBpatients showing persistent cognitive impairment at follow-up weresignificantly older at the time of surgery (P = 0.005). Individualcomparisons revealed that 45% of the patients undergoing CPB showedevidence of cognitive impairment soon after surgery. In 12% of thepatients, the cognitive sequelae persisted at follow-up. Both group dataand individual incidence rates revealed neither significant pre- postdifferences between the surgical groups nor a time-by-group interactioneffect. Variables directly associated with CPB were not significantlyassociated with the occurrence of cognitive impairment after surgery.CONCLUSIONS: We conclude that an important proportion of the cognitiveimpairment after cardiac surgery is likely to be due to nonspecific effectsof surgery.