Does extracorporeal circulation harm the brain?

Coronary artery bypass grafting (CABG) has been used routinely to manage advanced coronary artery disease for more than 40 years. Despite its clear value in managing cardiac disease, the effects of CABG surgery on the brain are not clear. After CABG, many patients report difficulty with memory, concentration, and depression.1–5 Their cognitive deficits generally have been dismissed as mild and transient, and the majority of patients return to a nearly preoperative cognitive state within 6 months.2,3 However, recent reports suggest that this short-term improvement may wane and cognitive deficits may reappear when patients are followed for longer postoperative intervals.1,6 In the milieu of a brain already vulnerable to chronic cardiovascular and cerebrovascular disease, brain injury from CABG surgery may further increase the risk of longer term cognitive decline. The questions of whether extracorporeal circulation during CABG causes cognitive decline or increases the risk of degenerative dementia have yet to be answered definitively. One way to directly address the effect of extracorporeal circulation on cognition is to compare traditional on-pump CABG with the recently developed off-pump CABG, which does not require extracorporeal circulation. A recent randomized, prospective study …