Postmortem studies suggest that coronary angiography does not always accurately delineate the extent of coronary-artery disease. We examined this problem in living human hearts by performing high-frequency epicardial echocardiography at the time of cardiac surgery. The ratio of the diameter of the lumen of the coronary artery to the thickness of its wall was used to quantify the severity of coronary lesions. In 11 patients with no angiographic evidence of coronary disease anywhere in the coronary tree, the mean (+/- SEM) ratio was 5.9 +/- 0.3. In 21 patients with angiographic disease at the site evaluated by echocardiography, the mean ratio was lower (2.3 +/- 0.2, P less than 0.05), reflecting encroachment into the arterial lumen by atherosclerotic plaque. In 15 patients with arterial segments that were angiographically normal but with arterial stenoses elsewhere in the coronary tree, the mean ratio was 4.1 +/- 0.3, with marked overlap with the values in the patients who had angiographic disease at the site of the echocardiographic evaluation. These results demonstrate, in living human hearts, that diffuse coronary atherosclerosis is often present when coronary angiography reveals only discrete stenoses. This finding suggests that coronary angiography may underestimate the severity and extent of coronary disease.

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There is currently no accepted approach for intraoperative evaluation of the technical adequacy of coronary artery bypass graft anastomoses. High-frequency epicardial echocardiography performed intraoperatively could assess coronary artery bypass graft anastomoses by providing on-line short-axis (cross-sectional) and longitudinal two-dimensional images of the vessels. To validate measurements of anastomoses with high-frequency epicardial echocardiography, luminal diameter determined by high-frequency epicardial echocardiography was compared with that determined histologically after perfusion fixation in 12 dogs studied after coronary artery bypass grafting. Technical errors were deliberately created in some grafts. The results of these animal validation studies showed that maximum luminal diameter of the anastomosis by high-frequency epicardial echocardiography correlated well with histologic measurements (r = .92; high-frequency epicardial echocardiography = 0.8 histology + 0.3). All deliberately created technical errors were detected by an independent observer using high-frequency epicardial echocardiography. After completion of the animal studies, we demonstrated the clinical applicability of this approach in 12 patients. Fifteen coronary artery bypass graft anastomoses were examined intraoperatively with high-frequency epicardial echocardiography. The measured maximum luminal diameter of the anastomosis was greater than the maximum luminal diameter of the native artery, as expected, in all end-to-side anastomoses. However, the maximum luminal diameter of the side-to-side anastomoses was equal to or slightly less than that of the native artery. In this initial patient group, minor technical errors were noted in two of 15 graft anastomoses. In conclusion, high-frequency epicardial echocardiography can accurately measure coronary arterial bypass graft anastomoses and has potential for intraoperative detection of technical errors and inadequacies. Such information may provide a means to detect and correct these technical errors and inadequacies intraoperatively.

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