Effects of longitudinal asymmetric distribution of a lipid core on plaque wall stress

Abstract

Effects of longitudinal asymmetric distribution of a lipid core on plaque wall stress IntroductionAtherosclerotic plaque rupture contributes to acute coronary syndrome, one of the leading causes of death in the world. It is composed of lipid rich necrotic cores and calcium deposits enclosed by a protective fibrous cap, which is a thin fibrous tissue between the lumen of the blood vessel and the lipid core. If the fibrous cap is disrupted, a cascade of events that include thrombosis, coronary occlusion, and subsequent myocardial infarction could occur (Libby, 2013). Studies have shown that the mechanical stress and structural integrity of the wall tissues of the plaque determine its susceptibility to disruption.Two different types of stresses act on the plaque tissues: circumferential tensile wall stress, which is caused by pulsating blood pressure, and luminal wall shear stress, which is caused by blood flow. Because tensional wall stress is several orders of magnitude higher than wall shear stress exerted by blood flow (Salger et al., 2005), plaque rupture has been attributed to circumferential wall stress (Ohayon et al., 2005), which is influenced by the morphology and mechanical properties of the plaque. It has been shown that atherosclerotic plaques with large plaque burdens (defined as the plaque area over the vessel area at the cross section) and thin cap thicknesses (less than 65 μm) are more vulnerable (Burke et al. 1997). Computational stress analysis has been performed in order to estimate the plaque wall stress using the idealized plaque models (Ohayon et al. 2008, Akyildiz et al., 2011, Zareh et al., 2015. Recently, three dimensional patient specific plaque models have been reconstructed from diagnostic medical images such as ultrasound, OCT, and MRI images for stress analysis (Nieuwstadt et al., 2013, Kelly-Arnold et al., 2013, Wang et al., 2015 and computational analysis has been performed. They provide a more realistic geometry for wall stress and flow analyses, but they are not ideally suited for obtaining accurate plaque wall morphology due to limitations that include Pengsrorn CHHAI*, Jin Hyun LEE* and Kyehan RHEE* *Department of Mechanical Engineering, Myongji University 38-2 Namdong, Cheoin-gu, Yongin, Gyeonggi-do 449-728, Republic of Korea E-mail: khanrhee@mju.ac.kr AbstractThe rupture of the atherosclerotic plaque is related to the mechanical stress and structural integrity of plaque wall tissues. In order to investigate the longitudinal asymmetry across the stenosis of the arterial plaque wall, asymmetric plaque wall models were constructed by skewing the lipid core distribution in the upstream direction. Wall stress and blood flow in the coronary artery models were computationally analyzed considering fluid and structure interaction. The values of maximum cap stress increased, and its location moved toward the proximal cap as asymmetry increased. Hemodynamic wall shear stress (WSS) did not change much owing to negligible changes in luminal geometry, but the maximum WSS and the spatial gra...

Effect of linear and Mooney–Rivlin material model on carotid artery hemodynamics

“…Fluid-structure interaction (FSI) is often used to study atherosclerotic plaque and its effect on local hemodynamics, initiation of plaque, growth, and rupture. Chhai et al [13] investigated the factors contributing to plaque rupture using FSI by examining asymmetric plaque models. The effect of maximum cap stress, WSS, was studied and concluded that the risk of plaque rupture was proportional to plaque asymmetry.…”