COLOR-FLOW DUPLEX ULTRASOUND ASSESSMENT OF INTERNAL THORACIC ARTERY GRAFT AFTER CORONARY-BYPASS

In an effort to develop a noninvasive method to evaluate now characteristics of the internal thoracic artery (ITA) graft after coronary artery bypass grafting, we performed color-now duplex ultrasound studies of the right and left ITAs of 42 patients before and 5 weeks after bypass grafting. The ITA was visualized with a duplex scanner (5.0-MHz probe) through the first or second intercostal space. We recorded the diameter, peak systolic velocity, and end-diastolic velocity for each patient. Preoperative measurements of the native ITAs were obtained easily in all patients. Postoperatively, the unused right ITA was seen in all patients. Postoperative visualization of the left ITA graft was adequate to make reliable measurements in 40 patients (95%). Postoperative end-diastolic velocities of the unused right ITA and the left ITA graft were markedly higher than the preoperative end-diastolic velocities of the native ITAs (p < 0.001). Whereas there was a marked increase in the peak systolic velocity of the postoperative unused right ITA (p < 0.05), the postoperative peak systolic velocity of the left ITA graft was significantly lower than the preoperative value (p < 0.001). We conclude that postoperative visualization of the left ITA graft is possible with the use of color-flow duplex ultrasound. Ultrasonic surveillance of postoperative ITAs may reveal ITA graft velocity abnormalities before overt graft failure is manifested in the patient who has undergone coronary artery bypass grafting.