Assessment of constitutive rheological models for the tissue and of its tickness on the prediction of Brain Aneurysms rupture

Abstract

Aneurysms are abnormalities formed in some regions of the human vascular systemand are characterized by dilated and thin regions of the arterial wall. One of the mostcommon types occurs inside the brain arteries in the Circle of Willis. These Intracranial Aneurysms are extremely dangerous, because in case of rupture they can cause sub-arachnoid hemorrhage, with consequent death or presence of permanent damage to the patient. Causes of Aneurysms have been investigated for a long time, and researchers agree that hemodynamic effects play a key role in the formation, growth, and rupture of Brain Aneurysms. With the development of scanning techniques of the cerebral vascular system, it has been possible to obtain the geometry of Aneurysms and numerical methods for the solution of blood flow have begun to be used. Since then, several researchers have been investigating the influence of biological and hemodynamic variables on Aneurysms rupture. However, only recently the fluid-structure interaction problem has been studied for the Aneurysm rupture problem, in which the variables of the Aneurysm wall - such as tensions and deformations - are essential to study the rupture event. The present work consists of a numerical investigation of the best constitutive model for the tissue of the Aneurysm wall in order to predict its rupture. Moreover, the model must account for the varying thickness of the Aneurysm and arteries walls. We will use the open-source software foam-extend which has a library for solving fluid-structure interaction problems. Geometric models of real Aneurysms will be used for the simulations. After the simulations, the fields of velocity, pressure, wall shear stress and wall tension will be analyzed in order to identify the possibility of rupture of the Aneurysm. (AU)