Effects of size and elasticity on the relation between flow velocity and wall shear stress in side-wall aneurysms: A lattice Boltzmann-based computer simulation study

Abstract

Blood flow in an artery is a fluid-structure interaction problem. It is widely accepted that aneurysm formation, enlargement and failure are associated with wall shear stress (WSS) which is exerted by flowing blood on the aneurysmal wall. To date, most of the computational studies of this problem assume rigid walls. In particular, in the case of side-wall aneurysms, the combined effect of aneurysm size and wall elasticity on intra-aneurysm (IA) flow characteristics is poorly understood. Here we propose a model of three-dimensional viscous flow in a compliant artery containing an aneurysm by employing the immersed boundarylattice Boltzmann-finite element method. This model allows to adequately account for the elastic deformation of both the blood vessel and aneurysm walls. Using this model, we perform a detailed investigation of the flow through aneurysm under different conditions with a focus on the parameters which may influence the wall shear stress. Most importantly, it is shown in this work that the use of flow velocity as a proxy for wall shear stress is well justified only in those sections of the vessel which are close to the ideal cylindrical geometry. Within the aneurysm domain, however, the correlation between wall shear stress and flow velocity is largely lost due to the complexity of the geometry and the resulting flow pattern. Moreover, the correlations weaken further with the phase shift between flow velocity and transmural pressure. These findings have important implications for medical applications since wall shear stress is believed to play a crucial role in aneurysm rupture.

Fluid-structure interaction simulation of tissue degradation and its effects on intra-aneurysm hemodynamics

“…To examine the role of geometry [14,37,49,50] for the above-described observation, we have conducted simulations of pulsatile flow through a curved tube without aneurysm (Fig. 8) and a different ideal aneurysm (Fig.…”

“…Numerical simulations provide a promising alternative. In a recent study [14] we have shown that blood flow inside an aneurysm exhibits complex features (such as flow disturbances) associ-ated with wall softness. Also fluid-structure interaction (FSI) simulations with complex wall models [15] have unveiled significant effects on WSS even in simplified arteries.…”

Fluid-structure interaction simulation of tissue degradation and its effects on intra-aneurysm hemodynamics

“…To examine the role of geometry (Lee et al 2008;Kurşun et al 2018;Wang et al 2020Wang et al , 2021 for the above-described observation, we have conducted simulations of pulsatile flow through a curved tube without aneurysm (Fig. 8) and a different ideal aneurysm (Fig.…”

“…Numerical simulations provide a promising alternative. In a recent study (Wang et al 2020), we have shown that blood flow inside an aneurysm exhibits complex features (such as flow disturbances) associated with wall softness. Also fluidstructure interaction (FSI) simulations with complex wall models (Balzani et al 2016) have unveiled significant effects on WSS even in simplified arteries.…”

The virtual physiological human gets nerves! How to account for the action of the nervous system in multiphysics simulations of human organs

“…In this study, we show that the ANN should not be omniscient, but it should carefully replicate the input-output structure of the ENS. Moreover, in multiphysics simulations, diseased states are usually hardcoded into the model [5,[12][13][14][15]. This study introduces a multiphysics + ANN model of the healthy intestine that, under certain conditions, 'becomes diseased' without the need to hardcode the disease state into the model.…”