Numerical Approach to Study the Behavior of an Artificial Ventricle: Fluid–Structure Interaction Followed By Fluid Dynamics With Moving Boundaries

Abstract

Heart failure is a progressive and often fatal pathology among the main causes of death in the world. An implantable total artificial heart (TAH) is an alternative to heart transplantation. Blood damage quantification is imperative to assess the behavior of an artificial ventricle and is strictly related to the hemodynamics, which can be investigated through numerical simulations. The aim of this study is to develop a computational model that can accurately reproduce the hemodynamics inside the left pumping chamber of an existing TAH (Carmat‐TAH) together with the displacement of the leaflets of the biological aortic and mitral valves and the displacement of the pericardium‐made membrane. The proposed modeling workflow combines fluid–structure interaction (FSI) simulations based on a fixed grid method with computational fluid dynamics (CFD). In particular, the kinematics of the valves is accounted for by means of a dynamic mesh technique in the CFD. The comparison between FSI‐ and CFD‐calculated velocity fields confirmed that the presence of the valves in the CFD model is essential for realistically mimicking blood dynamics, with a percentage difference of 2% during systole phase and 13% during the diastole. The percentage of blood volume in the CFD simulation with a shear stress above the threshold of 50 Pa is less than 0.001%. In conclusion, the application of this workflow to the Carmat‐TAH provided consistent results with previous clinical studies demonstrating its utility in calculating local hemodynamic quantities in the presence of complex moving boundaries.

Hemocompatibility and safety of the Carmat Total Artifical Heart hybrid membrane

“…Our numerical model includes both ventricles of the C-TAH with the oil and blood parts, the membrane and the valves. In order to simulate the interactions between fluids and solids, an FSI model coupled with CFD simulations was developed [22, 23]. The FSI simulation well describes the displacement and the stress of the solid parts.…”

“…The results of the simulation provided data consistent with the observations. These simulations, and some technicalities of the FSI settings, are described more in depth in a previous papers of ours [22]. Simulations produced as outputs the numerical values of the forces endured by the bloodstream, inside the C-TAH during the cycles of contraction.…”

Impact of lower limb movement on the hemodynamics of femoropopliteal arteries: A computational study

“…To analyse the effect of both anatomy and dynamic movement on local hemodynamics of FPA, flexions of the vessel at the level of the hip and knee joints were modeled by means of movingboundary CFD simulations. Specifically, the leg movement was imposed to the vessel wall (structure domain) to move the fluid domain, with an Arbitrary Lagrangian-Eulerian kinematic algorithm [24].…”

Artificial Organs 2018: A Year in Review

“…Giulia Luraghi et al of the Politecnico di Milano, Milan, Italy, investigated a numerical approach to reproduce the hemodynamics inside the left ventricle of the Carmat total artificial heart together with the displacement of the leaflets of the biological aortic and mitral valves and the displacement of the pericardium‐made membrane. The kinematics of the valves were accounted for by means of a dynamic mesh technique in the computational fluid dynamic (CFD) model.…”