Numerical study on the impacts of shunt pathway presence, anatomical characteristics, and occlusion degree in patients with spontaneous splenorenal shunt.

Spontaneous splenorenal shunts (SSRSs) are complex and associated with increased hepatic encephalopathy incidence. Improper treatments of SSRSs may cause portal hypertension (PH) deterioration. This study aims to evaluate the effects of the presence and various characteristics of SSRS on portal venous system hemodynamics and to explore the impacts of SSRS occlusion by investigating dynamic changes of portal venous pressure (PVP) before and after occlusion. Numerical simulations are performed through patient-specific models constructed from computed tomography angiography images and boundary conditions obtained from ultrasound velocity and balloon manometry measurements. SSRS models with different characteristics (diameter, tortuosity, orientation, and pressure difference) are designed. Embolic materials are simulated as a porous medium, with the porosity characterizing occlusion degree. Results show that patients with SSRS exhibit a 40.37% reduction in portal vein (PV) perfusion, associated with ∼18 times that of those without SSRS. Additionally, along with the SSRS diameter of clinical interest, tortuosity, orientation (α or β) and pressure difference also affect PV hemodynamics, e.g. tortuosity from 2.5 to 5.5 or β from -90° to +90° enhances PV prefusion by 10.14% or 57.95%; lower tortuosity and higher pressure difference can slightly alleviate PH. Furthermore, an occlusion degree from 10% to 90% increases PV perfusion and PVP by 4.74%-157.28% and 46.96%-50.69% over the preoperative level. Considering the risk of PH deterioration (the threshold under 150% preoperative PVP), 10%-50% occlusion degree may represent a potential safe range (49.31% enhancement in PVP at 50%). Results obtained can provide preliminary guidelines for high-risk SSRSs diagnosis and occlusion schemes determination.