Potential role of finite element model of abdominal aortic aneurysm in clinical decision making

Abstract

Introduction: AAA rupture occurs as a consequence of the imbalance between aortic wall's strength and the loading stress. FEM provides information on the regional distribution of stresses in the wall of AAA and proved to be a more accurate predictor of aneurysm rupture. The risk of rupture is expressed through peak wall stress (PWS) and rupture risk equivalent diameter (RRED) that includes wall strength in calculation. Aim: To determine the influence of FEM and subsequent biomechanical analysis of AAA on treatment decisions in common clinical practice. Material and methods: This prospective study included 48 patients with asymptomatic AAA. The specific anatomical and biomechanical parameters were determined by a FEM analysis: location of the PWS and diameter of the aorta, parietal thrombus in the level of PWS and the maximum value of the measured diameter (MD) as well as rupture risk equivalent diameter (RRED). Decision of treatment would change if maximal aneurysm diameter and RRED are on different sides of the 55 mm that is contemporary treatment threshold for AAA. Results: In 20 patients (41.67%) values of RRED could change treatment decisions. Four patients (20%) with aneurysm diameter (MD) less than 55 mm would be transferred to the group of patients with indications for surgical treatment because their RRED was higher than the limit of 55 mm. Sixteen patients (80%) would be transferred to the group of patients for further follow up without surgical treatment, because their RRED was less than the limit of 55 mm although their MD was higher than 55mm. Conclusion: Finite element model (FEM) of abdominal aortic aneurysm (AAA) and subsequent biomechanical analysis would lead to change of surgical indications for treatment of AAA in almost half of included patients.

Keywords

• Abdominal aortic aneurysm
• peak wall stress
• finite element model analysis
• changing decision about treatment