Abstract 670: Finite Element Analysis-derived Peak Wall Rupture Index Can Predict Rupture in Abdominal Aortic Aneurysms
Objectives: In abdominal aortic aneurysm (AAA) patients with high operative risks, it may be difficult to weigh the risks of surgery against the risk of rupture even if the treatment criterion, an aneurysm diameter larger than 55 mm, is fulfilled. It has been demonstrated that a significant portion of all large-diameter AAAs will never rupture. The aim of this study was to determine whether finite element analysis (FEA)-based rupture risk prediction could identify AAAs that ruptured within a two-year period.
Methods: We identified all patients who presented with AAA rupture in our catchment area during the years 2009-2013. Of the 130 patients diagnosed with ruptured AAA, 14 patients had a previous computed tomography angiography (CTA) of high quality conducted within two years prior to rupture. The aneurysms were semi-automatically segmented from CTA images and FEA was conducted using Vascops A4 Clinics. The biomechanical variables Peak wall stress (PWS) and Peak wall rupture index (PWRI = maximal wall stress/wall strength ratio) were calculated. FEA was also performed on a control group of 15 AAAs with diameters similar to the rupture group and two years of uneventful follow-up after CTA.
Results: Four women and 10 men, median age 82 years, with an aneurysm diameter range of 54 to 88 mm, were included into the rupture group. The control group consisted of three women and 12 men, median age 81 years, with an aneurysm diameter range of 52 to 91 mm. No significant differences in age, gender, smoking status, hypertension or body mass index existed. PWRI was significantly higher in the aneurysms that would later rupture compared to the control group (0.41 vs 0.34, p = 0.005) but no significant differences in PWS (212 vs 197 kPa, p = 0.20) or maximal diameter (61 vs 58 mm, p = 0.23) were detected. There was no significant difference in infrarenal aortic volumes (190 vs 144 cm3 p = 0.19) or intraluminal thrombus volumes (99 vs 59 cm3 p = 0.12) between the groups.
Conclusions: In this small cohort of AAA patients with a pre-rupture CTA within the last two years, finite element analysis that included both wall stress and wall strength estimations could predict rupture.
Author Disclosures: M. Lindquist Liljeqvist: None. A. Siika: None. R. Hultgren: None. T. Gasser: Employment; Significant; Scientific advisor of Vascops GmbH. Ownership Interest; Significant; Shareholder of Vascops GmbH. J. Roy: None.
- © 2015 by American Heart Association, Inc.