Blood Flow Analysis in Portal Vein System - Unsteady-State Case Study

Anatomical features and a complex vascular system characterize the liver. The blood flow results as a complex interaction between fluid, vascular system complex geometry and liver functional and structural features. The disease presence produces pathological changes that may induce hemodynamic perturbations not only due to geometry modification but especially due to liver perfusion alteration. The analysis of the blood flow dependence on the geometry variability in physiological condition could emerge in its parameterization and quantification. This may eliminate the confusion between blood flow modification due to geometry variability in physiological conditions and flow alteration due to pathological conditions or congenital anomalies presence. In this paper the analysis focuses on portal vein system and consists in blood flow analysis under unsteady-state conditions. The study involves the investigation of 12 patients by MRI techniques followed by 3-D portal vein system geometry acquisition, blood flow simulations based on mathematical models that include constitutive equations describing the hemodymanics and its relations with the deformable vessels wall. The computational technique applied to model the blood flow approaches both the velocity field and the pressure field. The vessels wall was considered elastic, coupling in this way the vessel/wall deformability problem. The blood flow analysis in physiological conditions enables the improvement of understanding of the complex blood flow behavior in the portal vein system; enables to identify critical information and to parameterize the domain of normal portal vein circulation.