Patient-specific hemodynamics and stress-strain state of cerebral aneurysms.

Purpose: Approximately 5% of the adult population has one or more cerebral aneurysm. Aneurysms are one of the most dangerous cerebral vascular pathologies. Aneurysm rupture leads to a subarachnoid hemorrhage with a very high mortality rate of 45-50%. Despite the high importance of this disease there are no criteria for assessing the probability of aneurysm rupture. Moreover, mechanisms of aneurysm development and rupture are not fully understood until now.

Methods: Biomechanical and numerical computer simulations allow us to estimate the behavior of vessels in normal state and under pathological conditions as well as to make a prediction of their postoperative state. Biomechanical studies may help clinicians to find and investigate mechanical factors which are responsible for the initiation, growth and rupture of the cerebral aneurysms.

Results: In this work, biomechanical and numerical modeling of healthy and pathological cerebral arteries was conducted. Patient-specific models of the basilar and posterior cerebral arteries and patient-specific boundary conditions at the inlet were used in numerical simulations. A comparative analysis of the three vascular wall models (rigid, perfectly elastic, hyperelastic) was performed. Blood flow and stress-strain state of the two posterior cerebral artery aneurysm models was compared.

Conclusions: Numerical simulations revealed that hyperelastic material most adequately and realistically describes the behavior of the cerebral vascular walls. The size and shape of the aneurysm have a significant impact on the blood flow through the affected vessel and on the effective stress distribution in the aneurysm dome. It was shown that large aneurysm is more likely to rupture than small aneurysm.