The Role of Tomographic Ultrasonography in Conduit Mapping before Coronary Artery Bypass Grafting.

ABSTRACT

OBJECTIVE: To assess the performance of tomographic ultrasonography (TUS) in providing images that will enable optimum choice of vein segment to harvest for coronary artery bypass grafting (CABG). METHODS: This was a prospective study of diagnostic accuracy. The index test was tomographic ultrasonography. The reference standard was intraoperative observation. The study was performed at the Vascular Imaging and Cardiothoracic Department at Wythenshawe Hospital, Manchester. Patients undergoing CABG who require vein mapping were included in the study. The main outcome measures were the number of tributaries identified in harvested vein segments, presence of varicosities, and usable length of vein. RESULTS: The TUS correctly identified 89 out of 111 vein tributaries in 10 patients resulting in a sensitivity of 80.2%. This resulted in a p value of 0.000001 using an exact binomial test, with a prior probability of 0.5. TUS had a sensitivity of 66.7% and a specificity of 100% in the identification of varicosities over 14 patients. TUS had 90% agreement with intraoperative observation in assessing usable length of vein over 14 patients. CONCLUSIONS: Our results show that TUS has a high sensitivity in identifying vein tributaries. This can be used to select veins with fewer tributaries for harvesting should TUS be used for preoperative vein mapping before CABG.