A Wss Based Hemodynamic Study on Venous Thrombosis Formation Conditions in Deep Veins

Abstract In this study, a general simulation framework for realistic blood flow that is in continues interaction with deformable venous valve is defined and its hemodynamic performance is compared with the steady fixed valve model for different rheological viscosity models. The main objective of the proposed model is to understand the flow properties and WSS based hemodynamic mechanisms of venous thromboembolism (VTE) more specifically toward the early diagnosis of the DVT formation and its early state contains the formation of venous stasis through hemodynamic indexes. A reliable shear index-based non-invasive thrombotic risk assessment model is not available in the literature by simulating the venous stasis condition of the patient’s DVT around venous valve leaflets. Based on Virchow’s triad, thrombosis mostly occurs due to the existing of statis in deep vein venous valve sinus beside vessel wall injury and hypercoagulability of blood. Additionally, vessel wall deformation and resulting sinus formation behind the venous valve may also lead to systemic and local factors creating stasis conditions. For this purpose, two different flow models including steady fixed venous valve and moving venous valve (based on FSI coupling) are studied. Evolution of stress fields in longitudinal and radial directions are studied. Then, we computed Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI) and Relative Residence Time (RRT) based on wall shear stresses. The combined effects of WSS and circumferential stress/strain (CS) on endothelial cells (EC) due to pulsatile flow and secondary back flow in venous valve region using vascular compliance in venous return is investigated for slow and high blood velocities. Time Averaged Transverse Wall Shear Stress (transWSS) index is used for capturing the multi directional flow conditions around the venous valve sinus. Finally, Multiple combined hemodynamic index analysis is performed for the possible thrombosis formation in venous sinus region. Comprehensive verification processes of the numerical model and its validation with the analytical result for a simple cylindrical pipe geometry are presented. Results are obtained for sinusoidal pulsatile inflow condition using five different blood velocities and detail discussion on FSI results and concluding remarks are presented.