Enhanced accumulation of LDLs within the venous graft wall induced by elevated filtration rate may account for its accelerated atherogenesis

Abstract

Objective: To test the hypothesis that the venous graft when implanted in an arterial bypass might endure a significantly elevated water filtration rate, leading to fast infiltration/accumulation of low-density lipoproteins (LDLs) within the graft wall and hence the accelerated atherogenesis.

Methods: We measured filtration rates of the swine femoral artery and lateral saphenous vein under venous and arterial hemodynamic conditions in vitro. Based on the measured filtration rates, we numerically simulated LDL transport in an arterial bypass model with a venous graft. Moreover, in order to validate the theoretical prediction, we measured DiI-LDLs uptake by both arteries and veins under arterial condition.

Results: The experimental results showed that when subjected to arterial hemodynamic condition, the filtration rate of the venous wall was increased sharply, and significantly higher than that of the artery. Moreover, different from the hydraulic conductivity of artery, the venous one would increase with increasing pressure. The numerical results showed that for the venous graft, both luminal surface LDL concentration and LDL accumulation within the vessel wall were significantly higher than those for the host artery. In addition, the experiment, which was used to confirm theoretical prediction, showed that the amount of DiI-LDLs uptake by the venous wall was much higher compared with arterial wall.

Conclusion: The present study suggests that the accelerated atherogenesis of the venous graft is attributable to its elevated filtration rate that may lead to both aggravated concentration polarization of LDLs and enhanced convective transport of LDLs into the graft wall.

Keywords: Accelerated atherosclerosis; Filtration rate; Low-density lipoprotein; Venous graft.