Oxidative stress and lipid retention in vascular grafts - Comparison between venous and arterial conduits

Background-Because saphenous vein grafts (SVGs) exhibit greater cellular he terogeneity and worse clinical outcomes than arterial grafts (AGs), we exam ined oxidative stress and lipid retention in different vascular conduits. Methods and Results-In a porcine model of graft interposition into carotid artery, superoxide anion (O-.(2)-) was measured at 2 weeks after surgery. S VGs demonstrated increased O-.(2)- production compared with AGs (SOD-inhibi table nitro blue tetrazolium reduction, P <0,01), The NAD(P)H oxidase inhib itor diphenyleneiodonium (P <0.01) abolished SVG-derived O-.(2)-, whereas t he inhibitors of other pro-oxidant enzymes were ineffective. The change in oxidative stress was also reflected by lower activity of the endogenous ant ioxidant superoxide dismutase in SVGs than in AGs (P <0,001), SVG remodelin g was associated with increased synthesis of sulfated glycosaminoglycans an d augmented expression of a core protein, versican. These changes were acco mpanied by SVGs retaining significantly more I-125-labeled LDL than AGs ex vivo (P <0.001). In hyperlipemic animals, lipid accumulation and oxidized e pitopes were preferentially noted in the intima of SVGs at 1 month after su rgery. Conclusions-This study demonstrated significant differences in the biology of SVGs and AGs, SVGs exhibited higher oxidative stress. LDL accumulation, and the presence of oxidized epitopes. These findings suggest that proather ogenic changes in SVGs may commence early after surgical revascularization.