Numerical Modeling of Blood Flow in Human Left Coronary Artery and In Vitro Study of Endothelial Cell Activation by Shear Stress

Abstract

The major scope of this study was to estimate the wall shear stress (WSS) distribution inside the left anterior descending (LAD) artery under normal and disease conditions. The LAD models (2D and 3D models) were constructed based on previous studies. This assisted in predicting the deviation of WSS estimation due to the selection of LAD model. The WSS distribution was estimated by computational fluid dynamic analysis of blood flow in LAD using FLUENT. The other purpose of this study was to understand the activation response behavior of endothelial cells (EC) exposed to varying shear stress. A cone and plate hemodynamic cell shearing device was used to shear the EC, based on WSS information from numerical simulation. The EC activation was measured based on their inflammatory response i.e., the amount of surface protein (ICAM-1 and TF) expressed. From the numerical studies, disturbed WSS distribution was found near the throat region. The WSS reached a peak value of around 14Pa at the center of throat in 80% stenosis condition. The recirculation zone formed downstream the throat possessed a low oscillating shear stress region. Besides, the 2D and 3D models estimated fairly similar results in the upstream location under normal and stenosis conditions but deviated near the throat region. It can be concluded that 2D model was sufficient for WSS estimation under normal conditions but not suggestible for disease conditions. The in vitro results revealed the EC activation and increased ICAM-1 expression when exposed to low oscillating shear stress (inside recirculation zone). Finally, the high WSS gradient in near the throat region and EC activation inside the recirculation zone may cause the lesion growth towards the downstream direction.