Experimental and computer model of plaque formation in the artery

Atherosclerosis is a progressive disease characterized by inflammation, monocyte-macrophage migration, and lipid accumulation in the vascular wall. Atherosclerosis is initially characterized by endothelial dysfunction, which favors lipid and cell elements crossing inside blood vessel wall. In this study, two experiments are calculated numerically. The first is Cheng et al. 2006 experiment with cast model on the carotid artery and the second is our pig experiment on the left anterior descending coronary artery (LAD) after 2 months of high fat diet. Experimental model of plaque formation on pig LAD is simulated numerically using a specific animal data obtained from intravascular ultrasound (IVUS) and histological data. The 3D blood flow is governed by the Navier-Stokes equations, together with the continuity equation. Mass transfer within the blood lumen and through the arterial wall is coupled with the blood flow and is modeled by the convection-diffusion equation. LDL transport in lumen of the vessel is described by Kedem-Katchalsky equations. The inflammatory process is solved using three additional reaction-diffusion partial differential equations. Matching of IVUS and histological animal data is performed using 3D histological image reconstruction and 3D deformation of elastic body. Lipids concentration in the intimal area of the low shear stress was 16% and for oscillatory zone 10% which is in good agreement with experimental data. Computed concentration of macrophages for pig model indicates that there is a newly formed matter in the intima, especially in LAD 15 mm region below left main artery bifurcation where plaque 8% of the area intima thickness was found in the area of lowered shear stress. Matching of plaque location and progression in time between experimental and computer model shows a potential benefit for future prediction of this vascular decease using computer simulation.