Computational Study on LDL Transfer from Flowing Blood to Arterial Walls

Summary

It is suspected that flow-dependent concentration polarization of low density lipoproteins (LDL) occurs at a blood/endothelium boundary due to an water-permeable nature of an arterial wall, creating favourable conditions for the genesis and development of several vascular diseases such as atherosclerosis, intimal hyperplasia and aneurysmus in the arterial system. Hence the effect of flow patterns and flow-induced wall shear stress (shear rate) on LDL concentration at a blood/endothelium boundary was investigated theoretically by means of a computer simulation of LDL transport from flowing blood to water-permeable walls of arteries having various geometry under conditions of a steady flow. It was found that in a straight artery, accumulation of LDL occurs near the vessel wall depending on the magnitude of wall shear rates, filtration velocity of water at the vessel wall, and diffusivity of LDL in blood under physiological conditions. Furthermore, through extension of the study to the cases of an axisymmetric stenosis, a T-junction, and curved segments, it was found that surface concentration of LDL is locally elevated in regions where wall shear stresses are low and where blood reaches after traveling a long distance along the vessel wall. These results strongly suggest that flow-dependent concentration polarization of LDL is playing an important role in the localization of various vascular diseases.