CEREBRAL ISCHEMIC DISORDERS AND CEREBRAL OXYGEN BALANCE DURING CARDIOPULMONARY BYPASS-SURGERY - PREOPERATIVE EVALUATION USING MAGNETIC-RESONANCE-IMAGING AND ANGIOGRAPHY

We compared the preoperative prevalence of small cerebral infarctions and carotid stenosis to jugular venous oxygen saturation (Sjvo(2)) dur ing coronary artery bypass grafting (CABG). Sjvo(2) served as an indic ator of whether cerebral oxygen supply meets demand in patients on car diopulmonary bypass (CPB). The study population consisted of 121 patie nts who were either older than 65 yr or had a history of cerebrovascul ar disease. The patients underwent preoperative cerebral magnetic reso nance imaging (MRI) and cervical magnetic resonance angiography (MRA) to detect small cerebral infarctions and carotid artery stenosis. Pati ents with atherosclerosis of the ascending aorta were identified by in traoperative epiaortic ultrasonography. Liberation of emboli from the aorta in these patients was prevented by modification of the standard operation. From preoperative MRI and MRA, 65 patients (54%) had small cerebral infarctions in the white matter or basal ganglia and nine pat ients (7%) demonstrated moderate or severe stenosis in the carotid art eries. Thirteen patients (11%) had moderate or severe atheromatous dis ease of the ascending aorta. The severity of aortic atherosclerosis wa s significantly correlated with the grade of carotid stenosis (P < 0.0 5). In patients with small infarctions, Sjvo(2) was significantly lowe r than in patients without infarctions (controls) at initiation of CPB , 30 min after aortic cross-clamping, and during the rewarming period of CPB (P < 0.05). Thus, small cerebral infarctions were not uncommon in elderly patients undergoing CABG. Patients with small cerebral infa rctions may be at risk for an imbalance in cerebral oxygen supply and demand during the rewarming period because they are unable to deliver the necessary compensatory blood flow.