Cerebral complications after cardiac surgery

• Cerebral injuty remains a major cause of morbidity and mortality after cardiac surgery. Previous studies have mainly focused on preoperative risk factors and intraoperative events but cerebral complications may also occur in the postoperative period. Cognitive impairment is common after cardiac surgery but the consequences of this complication for activities of daily life are less known. Safe driving involves a complex set of skills requiring preserved cognitive function. A substantial number of patients with heart disease are active drivers. The impact of postoperative cognitive dysfunction on driving performance, however, has not previously been investigated in this large patient group.In this thesis pre-, intra- and postoperative risk factors for focal cerebral complications were determined and the onset time of cerebral symptoms were evaluated in two cohorts of cardiac surgical patients, comprising 2480 and 3282 patients respectively. Data analysed were drafted from a clinical register and the surgical database of Linköping University Hospital Heart Center. Cerebral complication was delayed, i.e occurred after a free interval, in about one third of patients suggesting causes other than intraoperative events. Different risk factors were found for early and delayed cerebral complications suggesting different mechanisms of cerebral injury. Advanced age, preoperative hypertension, aortic surgery, prolonged cardiopulmonary bypass (CPB) time, intraoperative hypotension after completion of CPB, and arrhytlunia in the early postoperative period increased the risk for early cerebral complication. Female gender, diabetes, previous cerebrovascular disease, combined coronary artery bypass grafting (CABG) and valve surgery and arrhythmia on the thoracic ward increased the risk for delayed cerebral complication. Cognitive function and driving performance were evaluated in 27 patients before and 4-6 weeks after CABG. The patients underwent neuropsychological testing, an on-road driving test and a test in an advanced driving simulator. Twenty patients scheduled for percutaneous coronary intervention (PCI) served as controls. Complete data were obtained in 23 and 19 patients respectively. Furthermore cognitive function and driving performance in on-road driving of the 44 patients with complete tests before intervention were compared with controls of similar age without heart symptoms. Cognitive function and driving performance were already impaired in patients with coronary artery disease before intervention when compared with controls. After surgery 48% of the patients showed cognjtive decline compared to 10% after PCI. These patients also scored less in the on-road driving test to a greater extent than did patients without postoperative cognitive decline.

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