Saphenous vein grafts were concomitantly implanted as coronary and femoral bypass grafts using a senescent nonhuman primate model. Duplex ultrasound-based blood flow velocity profiles and vein graft and target artery dimensions were correlated with dimensional and histomorphologic graft remodeling in large, senescent Chacma baboons (n = 8; 28.1 卤 4.9 kg) during a 24-week period.
At implantation, the cross-sectional quotient (Qc) between target arteries and vein grafts was 0.62 卤 0.10 for femoral grafts vs 0.17 卤 0.06 for coronary grafts, resulting in a dimensional graft-to-artery mismatch 3.6 times higher (P < .0001) in coronary grafts. Together with different velocity profiles, these site-specific dimensional discrepancies resulted in a 57.9%卤 19.4%lower maximum flow velocity (P = .0048), 48.1%卤 23.6%lower maximal cycling wall shear stress (P = .012), and 62.2%卤 21.2%lower mean velocity (P = .007) in coronary grafts. After 24 weeks, the luminal diameter of all coronary grafts had contracted by 63%, from an inner diameter of 4.49 卤 0.60 to 1.68 卤 0.63 mm (P < .0001; subintimal diameter: 鈭?1.5%; P = .002), whereas 57%of the femoral interposition grafts had dilated by 31%, from 4.21 卤 0.25 to 5.53 卤1.30 mm (P = .020). Neointimal tissue was 2.3 times thicker in coronary than in femoral grafts (561 卤 73 vs 240 卤 149 渭m; P = .001). Overall, the luminal area of coronary grafts was an average of 4.1 times smaller than that of femoral grafts.
Although coronary and infrainguinal bypass surgery uses saphenous veins as conduits, they undergo significantly different remodeling processes in these two anatomic positions.