Modeling the hepatic arterial buffer response in the liver

Abstract

In this paper we present an electrical analog model for the hepatic arterial buffer response (HABR), an intrinsic regulation mechanism in the liver whereby the arterial flow counteracts the changes in portal venous flow. The model itself is a substantial simplification of a previously published model, with nonlinear arterial and portal resistors introduced to account for the dynamic HABR effects. We calibrate the baseline model using published hemodynamic data, and then perform a virtual portal occlusion simulation where the portal vein is half or fully occluded. The simulation results, which suggest that the increased arterial flow cannot fully compensate lost portal perfusion, are consistent with clinical reports and animal model findings. Since HABR functions in both the whole liver and liver graft after transplantation, we also simulate blood flow in a virtual right-lobe graft by adjusting the electronic component parameters in the electric circuit, and our model is able to reproduce the portal venous hyperperfusion and hepatic arterial hypoperfusion conditions due to the HABR effects.