[The Perioperative Management and Operative Strategy for Prevention of Stroke in Cardiovascular Surgery]

Stroke is an important cause of morbidity and mortality after cardiovascular surgery and its incidence has been reported as 1.5 to 8.7%. Preexisting cerebrovasuclar disease, stenotic lesions of the carotid artery and atherosclerosis of the ascending aorta are known to be significant anatomic risk factors. To prevent perioperative stroke, it is important to discuss the onset mechanisms. Intraoperative stroke is mainly caused by the embolization of scattered atheroscrelotic plaque. Carotid duplex scanning and magnetic resonance imaging (MRI) are useful methods for the preoperative screening of cerebrovascular stenosis and plaque. Enhanced computed tomography (CT) is a powerful tool to estimate the presence of severe atheroscrelotic plaque in the aorta. When severe plaque is present, the manipulation, cannulation or clamping of the diseased aortic segment should be prevented. Insufficient oxygenated brain blood flow is thought to be another mechanism of intraoperative stroke. Impaired cerebral autoregulation during caridopulmonary bypass has been reported. Thus, it is recommended to maintain a high mean arterial pressure during cardiopulmonary bypass, especially in patients with cerebrovasuclar occlusive diseases. Postoperative stroke is mainly caused by embolization of the thrombus. To prevent this, excessive hypovolemia and atrial fibrillation should be avoided. Preemptive usage of beta blockers is one option for preventing postoperative atrial fibrillation.