Ultrasonic imaging of the coronary arteries in open-chest humans: Evaluation of coronary atherosclerotic lesions during cardiac surgery

We explored techniques that would allow the surgeon to localize coronary artery lesions demonstrated angiographically or to supplement angiographic information in patients who are undergoing coronary artery bypass procedures by intraoperative scanning of the coronary arteries using ultrasound. A 9-MHz electronically focused water-path ultrasound scanner was first used to image the coronary arteries in three anesthetized, open-chest sheep. In a subsequent study, 10 human subjects undergoing cardiac surgery for valve replacement who had normal coronary angiograms were scanned during heart surgery to provide images of normal coronary arteries. The ultrasound probe was sterilized with gas and placed directly on the beating heart by the surgeon. In the third phase of this study, 21 patients with coronary artery disease were scanned and the ultrasonic appearance of their imaged coronary lesions was compared to independently interpreted angiographic estimates of percent obstruction, with close correlation (r = 0.91). The ultrasound scan could be used to identify lesions in vessels beyond proximal occlusion, which are not visualized well angiographically, and could localize the site of lesions to determine placement of saphenous vein bypass grafts. This new technique may provide a method of evaluating coronary atherosclerotic lesions during coronary artery surgery and aid decisions regarding placement of saphenous vein grafts.