Hemodynamic comparisons of different shunt positions and geometrical model simplification strategies in the simulation of transjugular intrahepatic portosystemic shunt (TIPS)

Abstract

Transjugular intrahepatic portosystemic shunt (TIPS) is a widely used surgery for portal hypertensive patients, whose potential postoperative complications are closely related to the hemodynamic condition of the portal venous system. The selection of shunt position in the surgery may affect the postoperative hemodynamics; however, it is difficult for clinical studies to investigate the influence. Therefore, this study aims to employ the computational model simulating TIPS to compare the hemodynamic differences resulting from different shunt positions, and also to investigate the influences of different geometrical model simplification strategies used in the TIPS simulation. For this purpose, the clinical data of two representative patients were retrospectively collected, based on which, the computational hemodynamic models of the portal venous systems after TIPS were constructed, incorporating three typical shunt positions (i.e. shunt at the left/main/right portal vein) and three types of geometrical model simplification. Results showed that among the models with different shunt positions, the area-averaged flow velocity magnitudes in the shunts were very similar, while the model with shunt at the main portal vein showed the lowest postoperative portal pressure and the smallest area of high wall shear stress near the portal venous bifurcation. Among the models using different geometrical model simplification strategies, the simulated blood pressures at the main portal veins were very similar, but showed marked differences near the shunt inlets. Moreover, the area-averaged flow velocity magnitudes in the shunts were almost the same, while the velocity distributions differed a lot, leading to the different spatial distributions of wall shear stress near the portal venous bifurcations and shunt walls. These results on one hand suggested that placing the shunt at the main portal vein is more beneficial for the patient; on the other hand, they proved the feasibility of utilizing simplified model to save computational cost without losing the accuracy when the pressure at the main portal vein is mainly focused on. These findings would assist clinical decision-making and promote more accurate and efficient TIPS simulations.