Modeling Of Transport Phenomena In Arteries

Atherosclerosis is an arterial disease that occurs due to the build-up of lipids, cholesterol and other substances in the arterial wall, collectively called plaque, leading to narrowing of the vessel lumen and, in time, disruption to the blood supply. The study of flow through atherosclerotic vessels is especially important since plaques not only cause a reduction in the vessel lumen but can rupture from the arterial wall, causing a blood clot in the vessel that may ultimately lead to heart attack or a stroke. Elevated level of oxidated low density lipoprotein (LDL) is a known risk factor associated with the genesis of atherosclerosis in arterial walls. Previous studies reported in literature have explored the transport of LDL through the arterial wall using analytical and mathematical models. In this work, we have presented a computational framework for the study of LDL transport in the lumen and the porous arterial wall. We have employed a four-layer arterial wall model and used governing equations to model the transport of LDL. We have used physiological parameters for the wall layers from literature and have validated the model based on the calculated filtration velocities and LDL concentration profiles in the arterial wall. We have further used this established model to study the effect of change in permeability and pressure on the LDL concentration. We have also studied the effect of pulsatile flow on the transport of LDL through the porous walls to examine the validity of the initial assumption of steady state and have seen that pulsation increases the time averaged net flux of LDL species by about 20%. We have next modeled a drug-eluting stent (DES), which is one of the popular remedies to cure atherosclerosis. The validation of DES model is followed by a combined study to analyze the effect of stent placement on LDL transport. Although there is no chemical reaction between the drug and LDL, we have noticed recirculation zones near the stent strut which result in accumulation of LDL molecules in the arterial wall. Future studies are aimed at incorporating variable porosity and permeability and a stenosed region in the geometry. The deformation of arterial wall due to pulsatile blood flow may lead to alteration of wall properties, which can give a realistic view of macromolecular transport