Abstract 107: Increased Peak Wall Stress in Women With Abdominal Aortic Aneurysms

Abstract

Objective: Women with abdominal aortic aneurysms (AAA) exhibit more rapid aneurysm growth and greater rupture risk at equivalent diameters relative to men. Evidence suggests that biomechanical peak wall stress (PWS) derived from finite element analysis of AAAs is a superior predictor of rupture compared to maximum transverse diameter (MTD). This study aimed to investigate differences in the calculated PWS of AAAs between men and women. Method: Men (n=35) and women (n=35) with infrarenal AAAs with 45-55mm MTD undergoing CTA were identified. Customized image processing algorithms extracted patient-specific AAA geometries from raw DICOM images. The resulting aortic reconstructions incorporated patient-specific and regionally resolved aortic wall thickness, intraluminal thrombus, and wall calcifications. Aortic models were loaded with 120mmHg blood pressure using commercially available FEA solvers. Results: Peak wall stress was found to be significantly higher in women (299±51 vs 257±53 kPA, P=0.001, see Figure). Neither MTD (50.5±3.1 vs 49.8±2.9 mm, P=0.34), mean aortic wall thickness (2.38±0.52 vs 2.34±0.50 mm, P=0.69), nor wall thickness at location of PWS (2.36±0.60 vs 2.20±0.46 mm, P=0.20) varied by sex. While there were no sex-associated differences in aneurysm volume (86.6±27.0 vs 94.8±25.5 cm 3 , P=0.76) or intraluminal thrombus volume (14.2±11.7 vs 16.3±13.4 mm, P=0.33), women’s AAAs had significantly increased maximum Gaussian curvature (0.032±0.011 vs 0.025±0.015 mm -2 , P=0.03). Conclusion: Comparably sized AAAs in women were shown to have significantly higher peak wall stress. Maximum gaussian curvature, a measure of aneurysm morphology, was significantly different between the two groups. These results suggest that men and women possess distinct aneurysm geometries, and that PWS-derived rupture risk prediction may provide a more reliable estimator of rupture risk in all patients.