Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
On the mechanics of ruptured and unruptured intracranial aneurysms: numerically assessing how different properties may affect their mechanical behavior
Submission Author:
Iago Lessa Oliveira , SP , Canada
Co-Authors:
Iago Lessa Oliveira, Carlos Baccin , José Luiz Gasche
Presenter: Iago Lessa Oliveira
doi://10.26678/ABCM.COBEM2023.COB2023-0240
Abstract
Intracranial aneurysms (IAs), a dangerous disease with up to 50 % mortality rate in case of rupture, is characterized as a dilatation of the cerebral arteries, most commonly occurring in the form of a sac. Biologically, their walls fit within the class of soft tissues. Numerical studies using patient-specific IA geometries have become increasingly popular as a tool to better understand the mechanics of the disease and, most pressing, to potentially help predict a rupture event. To that end, the mechanical properties of the tissue have to be known. Although these data are relatively scarce, recent experimental studies suggest that the mechanical properties of ruptured and unruptured aneurysms differ significantly. Consequently, it indicates that their mechanical behavior might be different. In this context, we compared the mechanical response, computed numerically, between ruptured and unruptured cases of patient-specific IAs. Pulsatile numerical simulations were carried out in twelve patient-specific IAs geometries using the one-way fluid-solid interaction solution strategy implemented in solids4foam, in which the blood flow is solved and its traction field is applied as the driving force of the wall motion. The IA and artery walls were assumed isotropic and their thickness and material properties were computationally created with a modeling in which these properties were assumed uniform over the aneurysm sac. Additionally, we used experimental data of ruptured and unruptured IA samples to obtain the mechanical constants for the Mooney-Rivlin law that was used to model the tissue constitutively. We found that the stress levels in the IAs sacs were not significantly different between the ruptured and unruptured groups. Actually, the stress levels were slightly higher on unruptured aneurysms. On the other hand, the ruptured IAs had a significantly higher maximum stretch compared to unruptured ones. This indicates that deformation-related properties of the wall may indicate rupture and, thus, may serve as a proxy parameter to indicate a possible rupture event.
Keywords
Intracranial aneurysms, wall mechanics, rupture status, solids4foam, Numerical analysis
