Intraoperative ultrasonic imaging of the ascending aorta in ischemic heart disease. In an attempt to locate any atherosclerotic lesion in the ascending aorta and to prevent embolization, intraoperative B-mode ultrasonography was performed in 100 patients with ischemic heart disease (31 women and 69 men). Ultrasonography was carried out with a 10-MHz probe placed directly on the ascending aorta. Ultrasonic imaging demonstrated an atherosclerotic lesion in the lower half of the aorta in 76 patients (76%), a lesion in the upper half of the aorta in 89 patients (89%), and a lesion at the orifice of the innominate artery in 99 patients (99%). Prospective palpation identified an atherosclerotic lesion in 12 (25%) of 48 patients. Thoracic computed tomography in 79 patients showed calcification in the lower half of the aorta in 6 patients (7.6%) and in the upper half of the aorta in 11 (13.9%). Palpation and thoracic computed tomography underestimated the frequency of atherosclerotic lesions. Intraoperative ultrasonography accurately identified atherosclerotic disease. This technique allows the surgeon to modify cannulation, aortic clamping, and operative technique to reduce the risk of perioperative stroke due to embolization of atherosclerotic debris from the ascending aorta. 