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2 Acta of Bioengineering and Biomechanics

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

Ivanov D., Dol A., Polienko A.

Acta of Bioengineering and Biomechanics

2016

Vol. 18, no. 2

9--17

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.

Analysis of the mechanical parameters of human brain aneurysm

Brigitta K. T., Raffai G., Bojtar I.

Acta of Bioengineering and Biomechanics

2005

Vol. 7, nr 1

3-22

Cardiovascular disease is one of the most frequent reasons of mortality in the western word. Nowadays the mechanical properties of biological soft tissues were treated from a continuum mechanical perspective. The aim of this article is to investigate the mechanical response of arterial tissue. We present some three-dimensional finite element model to study the mechanical effects. The arterial wall is composed mainly of an isotropic matrix materiał (elastin) and collagen fibers from two families which are arranged in symmetncal spirals. These fibers induce the anisotropy in the materiał response. So the constitutive law of an artery is orthotropic. We want to develop a new constitutive law for arterial wall mechanics. In addition we make a comparative study of some material model used in the literature to describe the mechanical response of arteries. These are the following models: 1. Linearly elastic model. 2. Neo-Hookean model for incompressible materials. 3. Mooney-Rivlin model for incompressible materials. For this reason we make uniaxial and biaxial measurements to have appropriate parameters for the underlying material models. We investigate the biomechanical properties of strips from human cerebral aneurysms from surgery and cadavers. (An aneurysm is a bulge along a blood vessel.) Meridional and circumferential. thick and thin parts were distinguished respectively. This paper focuses on the analysis of the haemodynamic pattern and biophysical properties of cerebral aneurysms. diagnosed aiid delineated in living human individuals. The aim of this research is to estimate stresses at critical points of the aneurysm wall and its parent artery, and to estimate the likelihood of a later aneurysm rupture.