15 th Annual CFD Symposium, August 9-10, 2013, Bangalore 1 CP37 EFFECT OF STENTGEOMETRY ON NEOINTIMAL HYPERPLASIA CAUSING RESTENOSIS IN STENTED CORONARY ARTERY: A TIME DEPENDENT CFD ANALYSIS Zeya Ahmad Quadri 1# , Mohammad Faisal Khan 1 , Prakash S. Kulkarni 2 , Mohammad Farman Ali 3 , Ugur Guven 1 , Karthik Sundarraj 1 1 Department of Aerospace Engineering, University of Petroleum and Energy Studies, Dehradun 2 Department of Aerospace Engineering, Indian Institute of Science, Bangalore 3 Department of Orthopedics, Patna Medical College and Hospital, Patna # zeya.quadri@stu.upes.ac.in ABSTRACT This paper presents a time dependent computational fluid dynamic analysis of effect of stentprofile on neointimal hyperplasia which causes re-occurrence of the stenosis in coronary stented artery. Three different cases of strut profile is simulated using phase contrast MRI based inlet velocity waveform. The basic objective of this work is the calculation of wall shear stress for different cross section of stent and their comparison using pulsatile velocity waveform. It has been established that streamlining the geometry with flow will decrease the area exposed to critical wall shear stress less than 0.5 Pa eventually decreasing the chances of neointimal hyperplasia. Keywords: Atherosclerosis, Neointimal Hyperplasia, Restenosis, CFD, Cardiac Cycle Introduction: Coronary Heart Disease (CHD) due to atherosclerosis is the single most common cause of death in developed nation. Coronary artery supply blood containing oxygen and nutrients to the heart muscle and surrounding tissues. Atherosclerosis is an indolent, chronic arterial disease involving inflammation and thickening of the walls of medium- and large-sized vessels, with potentially lethal sequelae [1]. An atherosclerotic lesion is an accumulation of lipids and inflammatory cells, within the arterial wall, which becomes more complicated and extensive and deforms the involved artery, with time.Coronary Stent is an artificial support device used in the coronary artery to keep the vessel open. Unfortunately, the stented artery is also susceptible to restenosis. Angiographic restenosis is commonly defined as a loss greater than 50% of the initial arterial diameter gained from the stenting procedure [2]. The primary process which leads to in-stent restenosis is Neointimal Hyperplasia, which is the excessive growth of tissue inside the stented segment. It has been exhibited that wall shear stress (WSS) and Wall Shear Stress Gradient (WSSG) have major impact on restenosis [3][4. Previous research shows that areas with low WSS (<0.5 Pa) displayed a significant increase in the thickness of the atherosclerosis plaque and the vessel wall [9]. Also Ku et al [5] reported a strong inverse correlation between low mean wall shear stress and atherosclerosis. Previously, 3D time dependent analysis had been performed using pulsatile velocity waveform for different cases such as alteration in regional vascular geometry [11], analysis using flow divider [12], particle deposition and related hemodynamic parameter [13], influence of axial stent strut angle [14] and effect of stent sizing [15]. Geometry and Mesh Generation: CAD Model of stented artery flow domain with different profiles was generated using Pro-Engineer Wildfire 4.0 ® . Length of stented artery is taken as 16 mm with additional length of 13 mm both side for parabolic velocity profile at stented region [6]. Cross section profile of stent is variable. Three different cross sections, rectangular, circular, and elliptical were chosen. Rectangular and circular sections were of width 0.2 mm and height 0.1 mm. Elliptical section was of width 0.2 mm and 0.05 mm. For computational efficiency, one quarter of a stented artery is considered for simulation. CAD geometry is imported to GAMBIT ® for mesh generation. Tri/hybrid grid is generated with T-grid type algorithm. For higher density of mesh near arterial wall size function for mesh is attached to the volume as start size of 0.05 with growth rate of 1.2 and size limit of 1. Contents