Regional biomechanical differences in human ascending aortic aneurysm wall: a paired anterior–posterior analysis

Regional heterogeneity of ascending aortic wall is thought to play a key role in the development of aortic aneurysms. Along the circumference of the vessel, anterior and posterior regions exhibit distinct characteristics. However, intra-patient comparative mechanical data between these regions remain limited in ascending aortic aneurysms with tricuspid aortic valve (TAV). Uniaxial tensile tests were performed on anterior and posterior aortic wall specimens from patients undergoing surgery for ascending aortic aneurysm with TAV. Comparisons were made for wall thickness, stiffness and strain at different deformation levels and at failure. Wall thickness differed significantly between regions, with higher values in the posterior wall (median 2.02 mm) than anterior wall (median 1.72 mm; p = 0.016). The anterior region exhibited greater stiffness at low strain levels, whereas the posterior wall showed higher failure strain, indicating increased extensibility. Posterior wall thickness was negatively correlated with maximum stress and near-failure elastic modulus, while in anterior region thickness was inversely associated with stress and strain at the transition point. Moreover, anterior and posterior walls exhibited different stiffness values depending on the level of deformation. These findings highlight the importance of incorporating regional biomechanical variability into patient-specific modelling and surgical decision-making to improve risk assessment in aneurysm.