Hemodynamic alterations in portal hypertension: A CFD-based study with emphasis on helical flow characteristics.

Purpose: Portal hypertension (PHT) leads to complications such as variceal bleeding, hepatic remodeling and thrombosis, driven by altered hemodynamics. This study aims to elucidate flow structure, shear stress and helicity changes under PHT, and their potential roles in promoting thrombosis and vascular remodeling. Methods: A patient-specific portal venous system model was reconstructed from CT images. Computational fluid dynamics (CFD) simulations were conducted to evaluate flow velocity, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT) and helicity. Results: Compared to the healthy model, the PHT condition demonstrated reduced flow velocity, lower TAWSS and elevated RRT, particularly near bifurcations. Moreover, the strength and symmetry of helical flow were significantly impaired in PHT, especially at the main portal vein bifurcation - an area frequently associated with thrombosis. Conclusions: This study highlights the role of hemodynamic disruption, particularly helicity loss, in the pathogenesis of PHT-related complications. CFD-based helicity analysis offers novel insight into biomechanical risk assessment and may inform future interventional strategies.