Effect of wall models on hemodynamics in left coronary artery: A comparative numerical study

Hemodynamic variables are vital for understanding the progression of cardiovascular diseases, but their accuracy depends on assumptions about arterial wall behaviour. Although the left anterior descending (LAD) branch of the left coronary artery (LCA) has been reported to be highly susceptible to atherosclerosis, there is a significant lack of studies comparing the effects of different wall models in this context. This study employs two-way fluid-structure interaction (FSI) simulations to investigate the impact of rigid, elastic, and hyperelastic wall models on the hemodynamics of a moderately stenosed LAD branch in an idealised LCA. The non-Newtonian properties of blood are captured using the Carreau viscosity model. Key hemodynamic parameters—primary velocity ($V_p$), streamwise vorticity, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and fractional flow reserve (FFR)—are evaluated across these models. Results show that the rigid model mostly exhibits higher $V_p$ and TAWSS at the stenosis throat compared to the elastic and hyperelastic models. It overestimates the peak TAWSS by 6.22 % and 14.46 % relative to the elastic and hyperelastic models, respectively, suggesting a higher risk of plaque rupture in rigid walls. In terms of plaque progression, both the pre- and post-stenotic regions of the arterial wall show the most extensive affected areas in the hyperelastic model compared to the rigid and elastic models, indicated by severe negative $V_p$and critically low values of TAWSS, and critically high values of OSI and RRT. The FFR value is the highest for the hyperelastic model (0.95), followed by the elastic (0.94) and rigid models (0.91). These findings underscore the importance of incorporating arterial wall flexibility in hemodynamic studies to improve risk assessment and clinical accuracy.