Effects of the atrium on intraventricular flow patterns during mechanical circulatory support

Abstract

Simulations of the ventricular flow patterns during left ventricular assist device (LVAD) support are mainly performed with idealized cylindrical inflow, neglecting the influence of the atrial vortex. In this study, the influence of the left atrium (LA) on the intra-ventricular flow was investigated via Computational Fluid Dynamics (CFD) simulations. Ventricular flow was simulated by a combined Eulerian (carrier flow)/Lagrangian (particles) approach taking into account either the LA or a cylindrical inflow section to mimic a fully support condition. The flow deviation at the mitral valve, the blood low-velocity volume as well as the residence time and shear stress history of the particles were calculated. Inclusion of the LA deflects the flow at the mitral valve by 25°, resulting in an asymmetric flow jet entering the left ventricle. This reduced the ventricular low-velocity volume by 40% (from 6.4 to 3.9 cm3), increased (40%) the shear stress experienced by particles and correspondingly increased (27%) their residence time. Under the studied conditions, the atrial geometry plays a major role in the development of intraventricular flow patterns. A reliable prediction of blood flow dynamics and consequently thrombosis risk analysis within the ventricle requires the consideration of the LA in computational simulations.

Left atrial appendage occlusion in ventricular assist device patients to decrease thromboembolic events: A computer simulation study

“…Individual CFD simulations can be performed with patient-specific models of LVAD patient’s hearts, which can be used to investigate the influence of both AF and LAAO on haemodynamics and blood flow. While in several computational studies, the intraventricular flow pattern during LVAD support was modeled without including the essential motion of the heart wall ( Chivukula et al, 2018 , 2019 ; Liao et al, 2018a ; Liao et al, 2018b ; Ghodrati et al, 2020 ; Ghodrati and Khienwad, 2021 ; Ghodrati and Schlöglhofer, 2021 ), To date, no CFD simulation study has examined the effects of AF on the contractile left heart or of LAAO in patients with LVAD support.…”