關于冠狀動脈旁路手術對記憶以及其他大腦功能影響的回顧性研究顯示：盡管手術可能具有暫時的短期效應，該手術可能不會導致后期的或者持久的神經系統缺陷。

研究人員發現：在某些長期研究中觀察到的后期認知下降可能與原有疾病的進展有關，例如腦血管疾病，而不是手術本身的作用。而例外情況包括老年患者和那些具有腦血管疾病風險的患者或者出現過腦卒中發作史的患者。

令人感興趣的研究證實：在手術之后3個月的時間內出現輕微病變，這是由于血流輕度紊亂或者其他手術相關因素造成的，諸如炎癥或者麻醉。當研究人員檢查最權威試驗研究的時候，他們在大多數患者3個月之后，沒有發現支持認知缺陷的強有力證據。

Johns Hopkins醫院神經病學教授Ola Seines博士說：“我們考慮在某些亞群患者冠狀動脈旁路移植手術之后，存在短期認知缺陷，但是沒有明顯的腦卒中發作，而這些病變通常是輕微暫時的。”

作者說，研究中發現的認知功能缺陷一個可能原因，是接受旁路手術的人群變得更加衰老與虛弱，患高血壓、糖尿病、先兆腦卒中以及其他疾病的機會更多。

Seines博士說：“我們相信接受冠狀動脈旁路移植手術的患者，不應當為后期可能出現的認知功能缺陷而感到沮喪。”
 
Bypass Surgery May Not Affect Brain Function
 
A broad retrospective review of the effects of coronary bypass surgery on memory and other brain functions has shown that while there may be transient short-term effects, the procedure probably does not cause late or permanent neurologic defects.

The researchers found that the late cognitive declines seen in some long-term studies are likely associated with the progression of underlying conditions, such as cerebrovascular disease, rather than the surgery itself. The exceptions might include older patients and those with risk factors for cerebrovascular disease or a history of stroke.

Existing studies confirm the existence of mild deficits in the period up to three months after surgery, which may be due to minor disruption in blood flow or other surgery-related factors, such as inflammation or anesthesia. When the researchers examined the most authoritative studies, they failed to find strong evidence that cognitive deficits persist after three months in most patients.

“We think that there are short-term cognitive changes after coronary artery bypass grafting (CABG) in a subset of patients, but absent a frank stroke, these changes are generally mild and transient,” said author Ola Seines, Ph.D., professor of neurology at Johns Hopkins Hospital (Baltimore, MD, USA).

One possible cause of the cognitive defects found in studies, say the authors, may be the fact that the population having bypass surgery is becoming older and sicker, with more hypertension, diabetes, previous strokes, and other disorders.

“We believe that patients should not be discouraged from having CABG because of the risk of late cognitive function,” added Dr. Seines.