A Finite Element Analysis Rupture Index (FEARI) as an Additional Toolfor Abdominal Aortic Aneurysm Rupture Prediction

ABSTRACT

Currently, abdominal aortic aneurysms (AAAs), which are a permanent dilation of the aorta, are treated surgicallywhen the maximum transverse diameter surpasses 5.5cm. AAA rupture occurs when the locally acting wall stressexceeds the locally acting wall strength. There is a need to review the current diameter-based criterion, and so it may beclinically useful to develop an additional tool to aid the surgical decision-making process. A Finite Element Analysis RuptureIndex (FEARI) was developed.

Ten patient-specific AAAs were reconstructed, and the corresponding wall stress computed. Previous experimental workon determination of ultimate tensile strengths (UTS) from AAA tissue samples was implemented in this study. By combiningpeak wall stress along with average regional UTS, a new approach to the estimation of patient-specific rupture riskhas been developed.

Ten cases were studied, all of which were awaiting or had previously undergone surgical AAA repair. A detailed examinationof these ten cases utilising the FEARI analysis suggested that there was a possibility that some of the AAAs mayhave been less prone to rupture than previously considered.

It is proposed that FEARI, used alongside other rupture risk factors, may improve the current surgical decision-makingprocess. The use of FEARI as an additional tool for rupture prediction may provide a useful adjunct to the diameter-basedapproach in surgical decision-making.

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