Risk factors for cerebral injury and cardiac surgery

Cerebral complications represent the leading cause of morbidity after cardiac operations. With the growing awareness of their social and economic importance, increasing attention is being given to their prevention. In the coronary artery bypass population, advanced age (≥75 years) is associated with an 8.9% neurologic deficit rate. Mortality is increased ninefold in the elderly patient with a neurologic deficit. Cardiopulmonary bypass has long been recognized as a cause of neuropsychologic deficits. Emboli are thought to be the causal agent. Retinal microvascular lesions during cardiopulmonary bypass as well as recent demonstration of widespread pathologic subcapillary arteriolar dilatations in the brain after cardiopulmonary bypass have been documented. Despite widespread interest in cerebral blood flow and neurologic deficits, there is no convincing evidence that defines a critically low or dangerously high level of flow. The ascending aorta represents a leading source of embolic neurologic injury. The use of intraoperative ultrasound to identify the diseased aorta may result in alternative operative strategies in an effort to minimize emboli and improve neurologic outcome. Existing literature offers conflicting views on optimal management of carotid artery stenosis in the coronary artery surgical patient. A trend that combined carotid endarterectomy and coronary artery bypass may often be appropriate will need confirmation through a multicenter clinical trial. Open cardiac surgical procedures, particularly in the aged population, carry a significant increased risk of adverse neurologic outcome. Postoperative arrhythmias may result in embolic neurologic deficit. A further understanding of risk factors for cerebral injury will be of value in developing therapeutic approaches to this major clinical problem.