Fluid structure interaction versus rigid‐wall approach in the study of the symptomatic stenosed carotid artery: Importance of wall compliance and resilience of loose connective tissue

Abstract

The purpose of this paper is to demonstrate the importance of a compliant wall approach in modeling of non‐Newtonian and non‐physiological blood flows. A case study of a stenosed and symptomatic carotid bifurcation was considered to show the influence of the wall‐resilience assumption on the flow parameters obtained with numerical simulations. Patient‐specific data concerning the geometry and flow conditions were collected and used to carry out two‐way coupled fluid structure interaction simulations of the pulsatile blood flow through carotid artery. The wall compliance was considered separately as related to the wall‐elasticity and as associated with the reaction of the loose connective tissue surrounding the carotid bifurcation. The obtained hemodynamic parameters were compared to those which were found in rigid‐wall simulations. The difference between the results obtained for rigid‐wall and compliant‐wall approaches for the peak‐systolic area‐averaged wall shear stress achieved 35%, whereas the difference between the time‐averaged local vorticity and shear strain reached, respectively, 42% and 43%. The influence of the highly resilient wall on the monitored hemodynamic parameters was significant even if time‐averaged values are compared, which suggests that these metrics are considerably overestimated if the wall compliance is not considered. Moreover, the findings show that the mechanical response of the loose connective tissue cannot be neglected in blood flow simulations. Additionally, this study indicates that stiffening of the arterial wall due to atherosclerosis significantly rises hemodynamic parameters. This explains the therapeutic benefits of surgical removal of plaque lesions formed in the carotid bifurcation (endarterectomy).

Predicting postinterventional rupture of intracranial aneurysms using arteriography-derived radiomic features after pipeline embolization

“…Nonetheless, several widely known limitations should be considered when evaluating the results of these computational fluid dynamics analyses; these include rigid wall assumptions, physiological flow-boundary conditions that are not patient-specific, and Newtonian blood properties ( 19 , 20 ). Rigid wall computational fluid dynamics models tend to overestimate pressure gradients, resulting in greater pressure increases than are actually present ( 21 ). Furthermore, the precise geometry of the stent in its deployed state is unclear, and the accuracy of the virtual stent placement technique must be improved ( 22 ).…”

Boundary Condition Options for Carotid Bifurcation Analysis, Using Doppler Velocity Measurements

“…This means that these methods may not be suitable for finding high Oscillatory Shear Index areas on the arterial wall, which is often linked with the formation of arterial diseases [60]. As a reference, it also has to be stated that because of the approximation of the rigid-wall geometry, all velocity results might be greater than in a more realistic elastic wall simulation [58].…”

“…The walls of the geometries were assumed to be rigid for the numerical simulations. The findings of Albadawi et al [57] show that the volumetric flow rate division between the outlets is unaffected by the rigidity of the wall, while Jodko et al [58] point out that in stenotic cases the elasticity of the wall reduces and rigid-wall approximations can have less effect on the results. The effects of the non-Newtonian properties of blood on the flow conditions are considered negligible, therefore, a Newtonian fluid with a density of 1055 kg/m 3 and dynamic viscosity of 0.0034 Pas was implemented.…”

Morphology and Hemodynamics of Cerebral Arteries and Aneurysms in a Rare Pair of Monozygotic Twins

“…Once we obtain the DSA information for twin B-RB, a more complete study with physiological boundary conditions will be conducted in the future. Additionally, this study did not incorporate arterial compliance into the simulation (e.g., the deformation effects between the arterial wall and the blood stream); although many studies involved fluid–structure interaction (FSI) between the arterial wall and blood for CA studies [ 33 , 34 , 35 , 36 ], there are still many limitations. Up to date, there is no accessible pathway to obtain accurate arterial wall thicknesses in entire cerebral arteries since the arterial thickness is not uniform as well as patient-specific, which vary along with specific locations and different patients significantly.…”