Underlying mechanisms of saphenous vein graft stenosis after coronary artery bypass caused by clipping of the side branches: an experimental study

BACKGROUND: Saphenous veins are regular bypass conduits selected in non-left anterior descending artery (LAD) coronary artery bypass graft (CABG) surgery. Despite the technical errors, acute thrombosis, intimal hyperplasia and arteriosclerosis which could lead to saphenous vein graft (SVG) failure, the metal-clipping-related SVG failure is unique and rare. This study was conducted to investigate the clinical and underlying mechanisms of the metal-clipping-related SVG failure. METHODS: We collected 6 typical cases of the metal-clipping-related SVG failure in 41 patients who were diagnosed graft stenosis by coronary angiograph after CABG in the Department of Cardiology, Beijing Anzhen Hospital, from January 2020 to September 2021. Furthermore, we built an in vitro model to verify the identical intravascular ultrasound (IVUS) pattern of metal clip. RESULTS: There were 6 in 41 cases of SVG stenosis caused by clipping of the side branches. We found that the stenosis of SVG caused by metal clipping mostly occurred at the corner and multipole clipping points. In this situation, great resistance could be felt when pushing the instruments through the stenosis and crystallized cholesterol was rarely caught by the distal protection device. We verified the similar IVUS pattern of metal clip at the side-branches of SVG in vitro. CONCLUSIONS: The metal-clipping-related stenosis may lead to SVG failure. The stenosis of SVG caused by metal clipping mostly occurred at the corner and multipole clipping points. IVUS showed great modality for clarification.