About the saphenous vein graft patencies after coronary artery bypass surgery

We congratulate the authors for their work (1). In this study, the morphological factors affecting the long-term patency of the grafts used for revascularization in coronary artery bypass graft surgery were examined. The type of graft used for revascularization, the diameter of the target vessel, and the stenosis ratio of the target vessel effective to determine long-term patency were determined. We agree with the authors' conclusions. No relationship between saphenous vein graft length and long-term graft patency was observed. However, for the saphenous vein, we do not agree with the authors' conclusion. The saphenous vein is generally about 5-7 mm in diameter. In some cases, this may be even higher, especially above the knee. The mean diameter of the target coronary artery is between 1-2 mm. Because of this diameter mismatch, saphenous vein anastomosed to the coronary artery will cause stagnation because of hemodynamics. Stagnation is shown as a shaded area in Figure 1. As the length of the saphenous vein increases, the area of stagnation will increase and the graft patency will decrease (Fig. 1). Longer and wider saphenous vein grafts will cause more blood to be pooled, and the graft patency will be further imparied. Therefore, a 10-mm diameter graft is not used in femoro-popliteal bypass. Unlike the study, we do not agree that saphenous vein graft length does not affect graft patency.