Hypoperfusion,hyperthermia,atrial fibrillation,genetic predisposition and systemic inflammatory response associated with CPB have been identified as pathophysiological mechanisms.However, some authors consider cerebral embolisation to be the prevalent mechanism of intraoperative brain injury after cardiac surgery,as gaseous or solid cerebral emboli can cause ischemia, inflammation and edema,consequently causing cerebral infarctions usually resulting with stroke,coma,encephalopathy, delirium and cognitive decline. Additionally,they may impair cerebrovascular reactivity (CVR).