Patient-specific computational fluid dynamics analysis of portal vein hemodynamics before and after balloon angioplasty following living donor liver transplantation: a proof-of-concept study.

Portal vein stenosis (PVS) is a clinically significant complication after living donor liver transplantation (LDLT) that can compromise portal hemodynamics and graft perfusion. Because conventional imaging primarily assesses morphology and local velocities, it provides limited insight into system-level hemodynamic alterations. Here, we developed a longitudinal, patient-specific computational fluid dynamics (CFD) framework to quantitatively evaluate portal venous hemodynamics before and after balloon angioplasty in an LDLT recipient with PVS. Patient-specific portal venous geometry was reconstructed from imaging data, with inlet conditions derived from Doppler ultrasound and outlet conditions modeled using a three-element Windkessel model. Key hemodynamic metrics-including velocity ratio, branch flow distribution, trans-stenotic pressure gradient, and wall shear stress-were analyzed before surgery and at 1 week and 6 months post-surgery. Balloon angioplasty markedly reduced velocity amplification and pressure gradients across the stenosis, normalized wall shear stress patterns, and induced progressive redistribution of intrahepatic portal flow, indicating system-level hemodynamic remodeling. This proof-of-concept study demonstrates that patient-specific CFD provides complementary functional information beyond conventional imaging and suggests its potential to facilitate longitudinal monitoring and early identification of hemodynamic changes, serving as a complementary tool for postoperative surveillance.