Abstract 18268: Development of First Patient-Specific Computational Model to Analyze Wall Stress in Ascending Thoracic Aortic Aneurysms

Abstract

Background: Ascending thoracic aortic aneurysms (aTAA) can rupture or dissect and rapidly become a lethal cardiovascular emergency. Peak aTAA wall stress may be a better predictor of rupture risk than diameter. However, in vivo models have never been validated and require zero-stress geometry, regional material properties, and residual stress. The goal of this study was to develop the first patient-specific computational models of aTAAs associated with bicuspid vs. tricuspid aortic valve using surgical specimens to accurately determine wall stress magnitudes. Methods: High-resolution micro-computed tomography of aTAA surgical specimens was used to construct zero-stress geometry. Bi-axial stretch testing of aTAAs in 4 quadrants provided stress-strain data to describe regional mechanical properties. Opening angle was used to determine residual stress. Finite element analyses were performed with LS-DYNA. Results: Elevated wall stress was seen in pockets in the anatomic left and right regions of bicuspid aTAA, primarily towards the sino-tubular junction, and in the left face of the inner lumen of the tricuspid aTAA more distally (Figure 1). Magnitudes of peak and mean wall stresses were similar between the bicuspid and tricuspid aTAAs. Conclusions: Wall stress magnitudes were relatively similar for these two aTAAs from bicuspid and tricuspid valve patients. Maximal wall stress areas may indicate sites more prone to rupture. Development of patient-specific aTAA models from surgical specimens is essential to determine true wall stress and to validate any in vivo -derived models. Such understanding is required to uncover the relationship between wall stress and rupture risk.