Between 1 and 5 percent of patients who have coronary artery bypass surgery suffer a stroke following surgery, and 30 percent have new brain lesions that do not produce symptoms and are seen only on MRI. In addition, up to 40 percent of patients develop long-term cognitive impairment. This study will identify risk factors that predict whether a person undergoing heart surgery will develop cerebral infarcts after surgery. It will also identify operative and inflammatory factors that may alter the risk, and will evaluate whether the small lesions are associated with cognitive decline at 6 months.