Risk evaluation of abdominal aortic aneurysms based on both sex and morphology

Aim: To predict the peak wall stress in abdominal aortic aneurysms (AAAs) considering both morphological factors (maximum diameter, asymmetry index, and wall thickness) and sex differences, in order to assess the risk of AAA rupture more accurately. Methods: Basic models of AAA focusing on different sexes with a range of morphological parameters were constructed. Using the Design-expert software for three-factor response surface methodology, 20 experimental models were built as well with the SolidWorks software. Fluid-structure interaction analysis was used to obtain stress distribution along the AAA wall. Polynomial regression equations were fitted to peak stresses in all experimental models. Results: Based on fluid-structure interaction simulation data in the nonlinear polynomial regression model, separate equations for peak wall stress in AAA with regard to males and females were obtained. Morphological factors and sex differences have significant influence on peak wall stress. In some models, even when the maximum AAA diameter was relatively small, the peak wall stress became high. For the same maximal transverse measurement, when the AAA wall was thin and the asymmetry index large, or the former was thick and the latter small, the peak wall stress observed in males was higher than that in females. Conclusion: To evaluate the risk of rupture of AAA more precisely and specifically, the present study proposes a new prediction method (based on equations) that includes more indicators such as sex and morphology, based on numerical biomechanical simulations, which were confirmed as such. This study provides a sex-specific clinical reference to assess the aforementioned risk of AAA rupture.