Modeling of low-density lipoprotein (LDL) transport in the artery—effects of hypertension

A robust four-layer model is presented to describe the LDL transport in the arterial wall coupled with the transport in the lumen. The endothelium, intima, internal elastic lamina (IEL) and media are all treated as macroscopically homogeneous porous media and the volume-averaged porous media equations are employed to model various layers, with Staverman filtration and osmotic reflection coefficients introduced to account for selective permeability of each porous layer to certain solutes. The physiological parameters within the various layers are obtained from literature. The set of governing equations for fluid flow and mass transport is descretized using a finite element scheme based on the Galerkin method of weighted residuals. Filtration velocity and LDL concentration profiles are developed at different locations for various clinical conditions. The results are consistent with previous numerical and experimental studies. Effects of hypertension and boundary conditions are discussed based upon the present model. Furthermore, the effects of pulsatile flows on LDL transport in the arterial wall are studied in some detail. Compared to previous transport models, the newly developed model is found to be a more robust tool for investigation of LDL accumulation within different arterial wall layers for various clinical conditions. This will be helpful in understanding the role of transmural transport processes in the initiation and development of atherosclerosis.