Dr. Tunick's major research interest has been the investigation of causes of stroke and peripheral embolization, particularly those involving atherosclerotic disease of the thoracic aorta. In 1990 he described the first stroke patients with a new finding on transesophageal echocardiography: severe atherosclerotic plaque in the aortic arch. After a case-control study demonstrated a very significant association of severe aortic plaque on TEE and emboli, a prospective study followed which showed that the risk of future stroke or TIA is 12% in a year, and 33% of patients had cerebral or peripheral embolization. The group of patients undergoing surgery with cardiopulmonary bypass is at especially high risk, as cannulation of the aorta may result in the dislodging of atherosclerotic material and thrombi from the aortic arch. A prospective study in the operating room showed that these atheromas are an important cause of stroke due to cannulation of the aortic arch during heart surgery. A subsequent study of 268 patients with aortic arch atheromas showed a very high risk of intraoperative stroke (approximately 12%, or 6 times higher than the average intraoperative stroke rate during cardiac surgery). This study also showed that arch endarterctomy, designed to try to prevent stroke, actually increases the risk. Recently Dr. Tunick completed a retrospective study of 519 patients with severe aortic plaque on TEE. The risk of future embolization to the brain or periphery was significantly reduced in those patients who were given statins. However, no effect was seen with the use of warfarin or antiplatelet therapy.