Modeling the hepatic arterial flow in living liver donor after left hepatectomy and postoperative boundary condition exploration

Abstract

Preoperative and postoperative hepatic perfusion is modeled with one‐dimensional (1‐D) Navier‐Stokes equations. Flow rates obtained from ultrasound (US) data and impedance resulted from structured trees are the inflow and outflow boundary condition (BC), respectively. Structured trees terminate at the size of the arterioles, which can enlarge their size after hepatectomy. In clinical studies, the resistance to pulsatile arterial flow caused by the microvascular bed can be reflected by the resistive index (RI), a frequently used index in assessing arterial resistance. This study uses the RI in a novel manner to conveniently obtain the postoperative outflow impedance from the preoperative impedance. The major emphasis of this study is to devise a model to capture the postoperative hepatic hemodynamics after left hepatectomy. To study this, we build a hepatic network model and analyze its behavior under four different outflow impedance: (a) the same as preoperative impedance; (b) evaluated using the RI and preoperative impedance; (c) computed from structured tree BC with increased radius of terminal vessels; and (d) evaluated using structured tree with both increased radius of root vessel, ie, the outlets of the postoperative hepatic artery, and increased radius of terminal vessels. Our results show that both impedance from (b) and (d) give a physiologically reasonable postoperative hepatic pressure range, while the RI in (b) allows for a fast approximation of postoperative impedance. Since hemodynamics after hepatectomy are not fully understood, the methods used in this study to explore postoperative outflow BC are informative for future models exploring hemodynamic effects of partial hepatectomy.

Hierarchical Modeling of the Liver Vascular System

“…In Debbaut et al (2012a) , partial hepatectomies were studied in a rat model and the dependence of the results with the use of different boundary conditions was shown, as well as with different ways of resecting the same proportion of liver. In Ma et al (2020) different boundary conditions were also explored in a liver resection model of the human liver, although this study focuses only on the hemodynamic variations in the hepatic artery network. The present study is a further contribution to exploring the appropriate boundary conditions to reproduce and study the main effects of a partial resection or transplantation of a human liver on flow and pressure.…”

Computational Modeling of the Liver Arterial Blood Flow for Microsphere Therapy: Effect of Boundary Conditions

“…This is the first 3D CFD study of the hepatic arterial tree aiming at quantifying the effect of downstream boundary conditions on the arterial tree hemodynamics in a realistic image-extracted computational domain with 46 outlets. Previous studies [ 6 , 7 ] had analyzed the effect of boundary conditions in lower-dimensional models such as 0D and 1D models. However, these models are high-level abstractions of the hepatic arterial blood flow and cannot reveal the effect of boundary conditions on the fine details of the flow such as velocity field, streamline and particle trajectory variations.…”

“…Among these parameters, the boundary conditions imposed on the computational domain play an important role [ 5 ]. Although the effect of boundary conditions on the lower-dimensional models (e.g., 0D and 1D model) of the hepatic artery has been discussed in the literature [ 6 , 7 ], it has not been quantitatively investigated for 3D CFD simulation of the hepatic arterial tree hemodynamics. Three-dimensional CFD simulation provides fine details of the flow internally within the 3D domain.…”

Hepatectomy-Induced Alterations in Hepatic Perfusion and Function - Toward Multi-Scale Computational Modeling for a Better Prediction of Post-hepatectomy Liver Function

“…In contrast, approaches simulating CFD allow detailed capture of postoperative hepatic hemodynamics in reconstructed vascular geometries. CFD models have been applied to study the changes in hemodynamics following hepatectomy in humans (Ho et al, 2010(Ho et al, , 2012Ma et al, 2020;Lin et al, 2021). CFD approaches can be computationally very intensive (Lin et al, 2021).…”