Validation of Non-Invasive Endothelial Shear Stress (ESS) Estimations of Coronary Artery Haemodynamics via In-Silico and In-Vivo Modelling

Abstract

Endothelial shear stress (ESS) is parallel frictional force exerted by blood flow on the coronary luminal surface and is associated with the development and progression of atherosclerosis. Computational fluid dynamics (CFD) is an engineering method used to analyse fluid flow and has been increasingly applied to simulate ESS. However, current CFD-ESS estimates have never been validated and can display significant variability between research groups. This study aims to provide a comparative analysis of coronary flow using in-silico modelling of coronary flow and particle image velocimetry (PIV). A proximal left anterior descending (pLAD) coronary phantom model was constructed from a patient who had received same day cardiac computed tomography angiography (CTCA) and invasive coronary haemodynamic (Combowire XT) assessment. Patient-specific coronary flow data was applied to CFD boundary conditions and a mock circulatory loop. CFD via PIV under steady flow in a 4-times-scaled model was validated. Same plane velocity field and flow patterns (at mid-luminal of pLAD) from both in-silico and in-vivo data were compared. Mean velocity contours and magnitude were analysed from CFD and PIV. Patient specific average peak velocity obtained from invasive assessment was 0.21m/s. Patient-specific velocity average from CFD was 0.22m/s. The approximated magnitude difference is 4.7%. Velocity contours and flow patterns simulated in the CFD were also comparable with the PIV results. Simulation data from CFD correlate well with experimental PIV results. This early data allows for a non-invasive approach to determine patient-specific coronary haemodynamics (such as velocity profiling and ESS).