Biomechanical characterisation of thoracic ascending aorta with preserved pre-stresses

Abstract

Mechanical properties of an aneurysmatic thoracic aorta are potential markers of future growth and remodeling and can help to estimate risk of rupture. Aortic geometries obtained from routine medical imaging do not display wall stress distribution and mechanical properties. Mechanical properties for a given vessel may be determined from medical images at different physiological pressures using inverse finite element analysis. However, without considering pre-stresses, the estimation of mechanical properties will lack accuracy. In the present paper, we propose and evaluate a mechanical parameter identification technique, which recovers pre-stresses by determining the zero-pressure configuration of the aortic geometry. We first validated the method on a cylindrical geometry and subsequently applied it to a realistic aortic geometry. Verification of the assessed parameters was performed using synthetically generated reference data for both geometries. The method was able to estimate the true mechanical properties with an accuracy ranging from 98% to 99%.

Wall-to-Lumen Ratio Estimation from Excised Ascending Aortic Aneurysm Rings

“…Furthermore, assessing the physiological pre-stresses within the vessel wall becomes challenging in the absence of information on the zero-pressure geometry [4] because the vessel wall undergoes deformation with respect to the unloaded zero-pressure geometry. Computational algorithms devised for the estimation of physiological pre-stresses typically begin by approximating the unloaded geometry, followed by applying pressure to this configuration until it reaches the physiological pressure [4]. However, they lack any kind of information on the unloaded geometry.…”