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The walls of the blood vessels involved with cerebral aneurysms present different mechanical properties, when compared with those of normal artery. Consequently the models which may describe then predict an aneurysm rupture need as input their mechanical properties. This paper describes the experimental determination of the mechanical properties of the tissues of the blood vessels affected with a cerebral aneurysm. In particular, we determine and discuss the critical elongation and the rupture strength. The affected tissues were obtained from surgical clipping and extraction; six specimens were tested. The mechanical tests were performed in a tensile device. The experimental data was fitted numerically with a Mooney-Rivlin hyper elastic model. The model was compared with previous published data. [ABSTRACT FROM AUTHOR]

Intracranial saccular aneurysms tend to be thin walled and stiffer compared with a normal artery. The current work describes computational structural dynamics (CSD) in an anatomically realistic model of a cerebral aneurysm located in the ophthalmic region, using different wall thickness, model data for the artery and aneurysm, and geometry size. The model was obtained from three-dimensional rotational angiography image data. The wall was assumed three-dimensional hyperelastic solid with different thickness in the artery and in the aneurysm regions. The effects of carotid siphon length are reported. The CSD was solved with the finite elements package ADINA. The predictions of stress and strain on the aneurysm wall were compared. [ABSTRACT FROM AUTHOR]

Haemodynamically induced stress plays an important role in the progression and rupture of cerebral aneurysms. The current work describes computational fluid dynamics (CFD), fluid-structure interaction (FSI) and computational structural dynamics (CSD) simulations in an anatomically realistic model of a carotid artery with two saccular cerebral aneurysms in the ophthalmic region. The model was obtained from three-dimensional (3D) rotational angiographic imaging data. CFD and FSI were studied under a physiologically representative waveform of inflow. The arterial wall was assumed elastic or hyperelastic, as a 3D solid or as a shell depending on the type of modelling used. The flow was assumed to be laminar, non-Newtonian and incompressible. The CFD, FSI and CSD models were solved with the finite elements package ADINA. Predictions of velocity field and wall shear stress (WSS) on the aneurysms made using CFD and FSI were compared. The CSD model of the aneurysms using complete geometry was compared with isolated aneurysm models. Additionally, the effects of hypertensive pressure on CSD aneurysm models are also reported. The vortex structure, WSS, effective stress, strain and displacement of the aneurysm walls showed differences, depending on the type of modelling used. [ABSTRACT FROM AUTHOR]

A sensitivity study of the results provided by computational fluid dynamics (CFD) in models of cerebral aneurysms including fluid structure interaction (FSI) was performed. With 83 reconstructed models of cerebral aneurysms, a geometrical study was done and one case was selected for a detailed study of the computational fluid dynamics. In this model the number of carotid siphon used for the CFD simulations was varied. In the FSI study, five simulations were conducted varying the elastic modulus of the artery and the arterial wall thickness, and the effect of hypertension on the results was reported. The FSI simulations have shown that the most important parameter that affects the aneurysm wall stress state is the arterial hypertension with maximum stress of around 900 kPa. It is concluded that FSI simulations must be used to simultaneously determine the wall stress and the fluid dynamics inside cerebral aneurysm. [ABSTRACT FROM AUTHOR]