MECHANISM OF STROKE COMPLICATING CARDIOPULMONARY BYPASS-SURGERY

Background: Stroke is a devastating complication of cardiopulmonary by pass (CPB) surgery which occurs in 1 to 5% of cases. Strategies to red uce its incidence require a knowledge of the underlying pathology and aetiology. Aims: To determine the incidence, pathology and aetiology o f stroke complicating CPB. Methods: Prospective review of clinical, op erative and cranial CT scan findings in all cases of stroke complicati ng CPB procedures in our institution over an 18 month period. Results: Twenty-one (1.6%, 95% CI 0.9-2.3%) cases of stroke were identified fr om 1336 CPB procedures. Cranial CT scan, performed in all but one pati ent, was normal in three patients or consistent with ischaemic stroke in 17 patients. There were no cases of haemorrhagic infarction or intr acerebral haemorrhage. It was difficult to differentiate embolic and b orderzone infarcts in two cases. After considering the clinical, opera tive and CT scan features together, 12 (57%, 95% CI 36-78%) of the cas es were felt to be embolic in origin and nine (43%, 95% CI 22-64%) due to hypoperfusion in a borderzone. Conclusions: This study demonstrate s that stroke remains an important complication of CPB procedures with an incidence in our series of 1.6%. The pathologic type of stroke is predominantly ischaemic in nature due to either cerebral embolism or b orderzone infarction. Strategies for stroke prevention in patients und ergoing CPB should be targeted primarily at these two mechanisms.