Occlusive changes at the coronary artery--bypass graft anastomosis. Morphologic study of 95 grafts.

Ninety-five bypass graft anastomoses in 52 patients dying up to 4 years after direct coronary revascularization were studied at autopsy by angiograms and serial histologic sectioning of the graft-artery anastomosis. When new coronary occlusions and narrowings occurred, they were adjacent to either the proximal or distal ends of the anastomosis and were due to compression or loss of circumference of the arterial lumen (40 per cent), thrombus formation (40 per cent), mural dissection of the coronary wall (8 per cent) or the combination of compression and thrombosis (12 per cent). Small coronary artery diameter, local atheromas, and extension of the arteriotomy into a branch vessel were significant factors predisposing to occlusive changes. The findings emphasize the importance of careful artery selection for bypass, the need to avoid local vascular disease and branch-points, and the technical difficulties encountered in the presence of local vascular lesions or small coronary arteries.