Our findings suggested that postoperative delirium was associated with pre-existing multiple cerebral infarctions on MRI, preoperative decline in global cognitive function and ascending aortic atherosclerosis in elderly patients undergoing coronary artery bypass graft surgery and increased risk of postoperative cognitive dysfunction.

Cerebral dysfunction after cardiac surgery remains a devastating complication and is growing in importance with our aging populations. Neurological complications following cardiac surgery can be classified broadly as stroke, encephalopathy (including delirium), or postoperative cognitive dysfunction (POCD). These etiologies are caused primary by cerebral emboli, hypoperfusion, or inflammation that has largely been attributed to the use of cardiopulmonary bypass. Preventative operative strategies, such as off-pump coronary artery bypass grafting (CABG), can potentially reduce the incidence of postoperative neurological complications by avoiding manipulation of the ascending aorta. Although off-pump CABG is associated with reduced risk of stroke, there are no convincing differences in POCD between off-pump and on-pump CABG. Recently, the focus of postoperative neurological research has shifted from managing cardiopulmonary bypass to patient-related factors. Identifying changes in brains of aged individuals undergoing cardiac surgery may improve strategies for preventing cerebral dysfunction. Advanced age is associated with more undiagnosed cerebrovascular disease and is a major risk factor for stroke and POCD following cardiac surgery. Preoperative cerebrovascular evaluation and adaptation of surgical strategies will provide preventative approaches for cerebral dysfunction after CABG. This review focuses on recent findings of the relationship between perioperative stress and underlying fragility of the brain in cardiac surgical patients.

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ObjectivesPostoperative cognitive dysfunction (POCD) is recognized as a complication in the elderly after cardiac surgery. Imaging of the brain provides evidence of neurodegeneration in elderly patients; however, abnormalities in brain structure and their relation to POCD are uncertain. This pilot study investigated whether loss of gray matter in the bilateral medial temporal lobe (MTL), seen in preoperative MRI, was associated with POCD.MethodsData were collected prospectively on 28 elderly patients scheduled for elective cardiac surgery. MRI of the brains of all patients were assessed for prior cerebral infarctions, and carotid and intracranial arterial stenosis. Patients also completed six neuropsychological tests of memory, attention and executive function before and after surgery. POCD was defined as an individual decrease in more than two tests of at least 1 standard deviation from the group baseline mean for that test. The degree of gray matter loss in the MTL of each patient was calculated using voxel-based morphometry with three-dimensional, T1-weighted MRI. This represented the degree of gray matter change as a Z score.ResultsPostoperative cognitive dysfunction was identified in 8 of the 28 patients (29%). Patients with POCD had significantly more white matter lesions on MRI, and greater loss of gray matter in the bilateral MTL (average Z score 2.0±0.9) than patients without POCD. An analysis by stepwise logistic regression identified gray matter loss in the MTL and cerebral infarctions on MRI as independent predictors of POCD.ConclusionsThese preliminary findings suggested that reduced gray matter in the bilateral MTL and white matter lesions existed in brains of elderly cardiac surgery patients who experienced POCD. Additional studies with larger sample sizes are needed to confirm these findings.

Patients with SBI were ranked at moderate risk of neurological complications after CABG between control and BI. Increased age, renal dysfunction, and preoperative cognitive impairment appeared to be strongly associated with SBI.

Off-pump CABG reduced postoperative NP dysfunction in elderly patients with severe systemic atherosclerosis compared to on-pump CABG.

These findings suggest that preoperative cognitive impairment associated with cerebral ischemic lesions and an increased risk of postoperative cognitive dysfunction existed in our patient cohort undergoing cardiac surgery.

These data suggest that men are more likely than women to have risk factors for stroke, including severe carotid artery stenosis, severe aortic atherosclerosis, and peripheral vascular disease. The rates of prior cerebral infarction and preoperative cognitive impairment were similar between genders.