Graft control by transit time flow measurement and intraoperative angiography in coronary artery bypass surgery

Background: The aim of this study was to compare the relationship between i ntraoperative transit time flow measurements and angiographic findings with long-term graft patency in 72 patients who under-went coronary artery bypa ss surgery. Methods: Transit time flow measurements with recording of mean flow and pul satility indexes were performed after completion of the anastomoses. Corona ry angiography was performed on-table while the patients were still in gene ral anesthesia, and then at follow-up three months and 12 months after surg ery. Based on angiography, the grafts were graded as type A (fully patent), type B (having more than 50% diameter reduction), or type O (occluded). Results: Of the 67 left internal mammary artery (LIMA) grafts, 51 (76%) wer e type A on-table, 14 (21%) were type B, and two (3%) were type O. Of the 5 7 saphenous vein grafts, 49 (86%) were type A, 7 (12%) were type B, and one (2%) was type O. For both LIMA and vein grafts, there were no differences in flow (p = 0.69 and 0.47, respectively) or pulsatility index (p = 0.79 an d 0.83) between type A and B. There were also no differences in flow (p = 0 .37 and 0.7) or pulsatility index (p = 0.37 and 0.24) between type B on-tab le that either normalized or persisted occluded at the follow-up. Transit t ime flow measurement failed to detect an occluded LIMA graft as shown by in traoperative angiography. Conclusions: Blood flow measurements performed intraoperatively could not i dentify significant lesions in arterial or vein grafts, and could not predi ct graft patency. We have become cautious in interpreting flow measurements alone and combine blood flow recordings with intraoperative angiography in the assessment of graft quality.