Effect of Stenosis Severity on Wall Shear Stress Based Hemodynamic Descriptors using Multiphase Mixture Theory

Abstract

A variety of wall shear stress (WSS) based hemodynamic descriptors have been defined over the years to study hemodynamic flow instabilities as potential indicators or prognosticators of endothelial wall dysfunction. Generally, these hemodynamic indicators have been calculated numerically using 'single phase' approach. In single phase models, the flow-dependent cell interactions and their transport are usually neglected by treating blood as a single phase non-Newtonian fluid. In the present investigation, a multiphase mixture-theory model is used to define the motion of red blood cells (RBCs) in blood plasma and interactions between these two-components. The multiphase mixture theory model exhibited good agreement with the experimental results and performed better than non-Newtonian single phase model. The mixture-theory model is then applied to simulate pulsatile blood flow through four idealized coronary artery models having different degrees of stenosis (DOS) severities viz., 30, 50, 70 and 85% diameter reduction stenosis. The maximum WSS is seen at the stenosis throat in all the cases and maximum oscillatory shear index (OSI) is seen in downstream region of the stenosis. Our findings suggest that for degree of coronary stenosis more than 50%, a more disturbed fluid dynamics is observed downstream of stenosis. This could lead to further progression of stenosis and may promote a higher risk of atherogenesis and plaque buildup in the flow-disturbed area. The potential atherosclerotic lesion sites were identified based on clinically relevant values of WSS, timeaveraged WSS gradient (TAWSSG), time-averaged WSS (TAWSS), and OSI. Finally, the change in potential atherosclerotic lesion sites with respect to DOS has been quantified.

3D Printed Biomodels for Flow Visualization in Stenotic Vessels: An Experimental and Numerical Study

“…The shape of the artery was a full cylindrical tube with a circular cross-section and an axisymmetric blockage (Figure 1). The selected diameter (3 mm) was based on the literature [40,41] and the length of the stenosis was defined as twice the normal diameter, an assumption applied by several researchers [42][43][44][45]. In addition, the length of the inlet zone (22 mm) was selected to ensure the creation of a fully developed inlet flow.…”

Modeling Blood Pulsatile Turbulent Flow in Stenotic Coronary Arteries

“…The diameter selection was based on real data obtained by Zhou et al [38] in 2017. Moreover, to develop the stenotic area, it was found that several authors [2], [39], [40] consider the length of the stenosis as twice the normal diameter of the artery. In addition, the entrance length was chosen so that the velocity profiles could be fully established proximal to the stenosis throat.…”

Mechanically Rotating Intravascular Ultrasound (IVUS) Transducer: A Review

“…The WSS is closely related to the development of atherosclerosis. For example, in the early stage of atherosclerosis, low and oscillatory WSSs that have stress values less than 1 Pa lead to inflammation and dysfunction of ECs, whereas, in the late stage, a WSS value of more than 7 Pa indicates erosion, which can be used to diagnose atherosclerosis [ 89 , 90 , 91 , 92 , 93 , 94 ].…”