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Carotid stenosis is a frequent coexisting condition in patients undergoing coronary artery bypass graft (CABG) surgery. The impact of carotid stenosis on cerebral perfusion is not fully understood. The purpose of this study was to determine the impact of carotid stenosis on cerebral blood flow velocity in patients undergoing CABG. Seventy-three patients undergoing CABG were prospectively recruited and underwent preoperative Duplex carotid ultrasound to evaluate the degree of carotid stenosis. Intraoperatively, transcranial Doppler ultrasound was used to record the mean flow velocity (MFV) within the bilateral middle cerebral arteries. In addition, during the period of cardiopulmonary bypass, regulators of cerebral hemodynamics such as hematocrit, partial pressure of carbon dioxide and temperature were recorded. The ipsilateral middle cerebral artery mean flow velocity was compared in arteries with and without carotid stenosis using a repeated measures analysis. Seventy-three patients underwent intraoperative monitoring during CABG and 30% (n=22) had carotid stenosis. Overall, MFV rose throughout the duration of CABG including when the patient was on cardiopulmonary bypass. However, there was no significant MFV difference between those arteries with and without stenosis (F=1.2, p=.21). Further analysis during cardiopulmonary bypass, demonstrated that hemodilution and partial pressure of carbon dioxide may play a role in cerebral autoregulation during CABG. Carotid stenosis did not impact mean cerebral blood flow velocity during CABG. The cerebrovascular regulatory process appears to be largely intact during CABG.

Delirium is an acute change in cognition which occurs frequently after coronary artery bypass graft (CABG) surgery. Cerebral microemboli, from plaque, air, or thrombus, have been hypothesized to contribute to delirium and cognitive decline after CABG. The purpose of this study was to determine if there was an association between cerebral microemboli and delirium after cardiac surgery. Non-delirious patients (n=68) were prospectively enrolled and underwent intraoperative monitoring of the middle cerebral arteries with transcranial Doppler (TCD). TCD signals were saved and analyzed postoperatively for microemboli manually, according to established criteria. Postoperatively, patients were assessed for delirium with a standardized battery. Thirty-three patients (48.5%) developed delirium after surgery. Microemboli counts (mean ± SD) were not significantly different in those with and without delirium (303 ± 449 vs. 299 ± 350; p=0.97). While intraoperative microemboli were not associated with delirium after CABG, further investigation into the source and composition of microemboli can further elucidate the long-term clinical impact of microemboli. [ABSTRACT FROM AUTHOR]

To investigate whether atherosclerosis of the ascending aorta, internal carotid arteries, and coronary arteries is predictive of postoperative delirium in subjects undergoing coronary artery bypass graft (CABG) surgery.Prospective cohort study.Boston Veterans Affairs Healthcare System.Thirty-six male veterans undergoing primary CABG surgery.Subjects underwent Duplex ultrasound to assess stenosis in the internal carotid arteries. Information on the ascending aortic plaque, as assessed by transesophageal echocardiogram, and the number of coronary vessels bypassed was collected. To create an atherosclerosis score, the number of atherosclerotic areas was added. A validated delirium battery was administered to the subjects preoperatively and on postoperative Days 2 and 5.Fifteen subjects (41.7%) developed delirium postoperatively. In bivariate analysis, carotid stenosis of 50% or more (relative risk (RR)=3.5, 95% confidence interval (CI)=1.5–8.1) and moderate-severe ascending aortic plaque (RR=2.9, 95% CI=1.0–8.5) were significantly associated with the development of delirium. There was a trend toward a significant association for three or more vessels bypassed (RR=9.6, 95% CI=0.6–145.3). After controlling for age, baseline cognition, and medical comorbidity, the atherosclerosis score was significantly associated with postoperative delirium (adjusted RR=2.7, 95% CI=1.1–6.8).In this preliminary report, atherosclerosis in the carotid arteries, aorta, and coronary circulation is associated with the development of delirium after CABG surgery. Further investigation into atherosclerosis as a risk factor for delirium is warranted. [ABSTRACT FROM AUTHOR]