Finite element analysis in asymptomatic, symptomatic, and ruptured abdominal aortic aneurysms: in search of new rupture risk predictors

P Erhart; A Hyhlik-Dürr; P Geisbüsch; D Kotelis; M Müller-Eschner; T C Gasser; H von Tengg-Kobligk; D Böckler

doi:10.1016/j.ejvs.2014.11.010

Finite element analysis in asymptomatic, symptomatic, and ruptured abdominal aortic aneurysms: in search of new rupture risk predictors

Eur J Vasc Endovasc Surg. 2015 Mar;49(3):239-45. doi: 10.1016/j.ejvs.2014.11.010. Epub 2014 Dec 24.

Authors

P Erhart¹, A Hyhlik-Dürr¹, P Geisbüsch¹, D Kotelis¹, M Müller-Eschner², T C Gasser³, H von Tengg-Kobligk⁴, D Böckler¹

Affiliations

¹ Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
² Department of Radiology, Ruprecht-Karls University Heidelberg, Germany.
³ Department of Solid Mechanics, Royal Institute of Technology, Stockholm, Sweden.
⁴ Department of Radiology, Ruprecht-Karls University Heidelberg, Germany; Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Inselspital, Bern, Switzerland.

PMID: 25542592
DOI: 10.1016/j.ejvs.2014.11.010

Abstract

Objectives: To compare biomechanical rupture risk parameters of asymptomatic, symptomatic and ruptured abdominal aortic aneurysms (AAA) using finite element analysis (FEA).

Study design: Retrospective biomechanical single center analysis of asymptomatic, symptomatic, and ruptured AAAs. Comparison of biomechanical parameters from FEA.

Materials and methods: From 2011 to 2013 computed tomography angiography (CTA) data from 30 asymptomatic, 15 symptomatic, and 15 ruptured AAAs were collected consecutively. FEA was performed according to the successive steps of AAA vessel reconstruction, segmentation and finite element computation. Biomechanical parameters Peak Wall Rupture Risk Index (PWRI), Peak Wall Stress (PWS), and Rupture Risk Equivalent Diameter (RRED) were compared among the three subgroups.

Results: PWRI differentiated between asymptomatic and symptomatic AAAs (p < .0004) better than PWS (p < .1453). PWRI-dependent RRED was higher in the symptomatic subgroup compared with the asymptomatic subgroup (p < .0004). Maximum AAA external diameters were comparable between the two groups (p < .1355). Ruptured AAAs showed the highest values for external diameter, total intraluminal thrombus volume, PWS, RRED, and PWRI compared with asymptomatic and symptomatic AAAs. In contrast with symptomatic and ruptured AAAs, none of the asymptomatic patients had a PWRI value >1.0. This threshold value might identify patients at imminent risk of rupture.

Conclusions: From different FEA derived parameters, PWRI distinguishes most precisely between asymptomatic and symptomatic AAAs. If elevated, this value may represent a negative prognostic factor for asymptomatic AAAs.

Keywords: Abdominal aortic aneurysm; Aorta; Finite element analysis (FEA); Rupture risk; Wall stress.

Publication types

Comparative Study

MeSH terms

Aged
Aged, 80 and over
Aortic Aneurysm, Abdominal / complications
Aortic Aneurysm, Abdominal / diagnostic imaging
Aortic Aneurysm, Abdominal / physiopathology*
Aortic Rupture / diagnostic imaging
Aortic Rupture / etiology
Aortic Rupture / physiopathology*
Aortography / methods
Asymptomatic Diseases
Biomechanical Phenomena
Finite Element Analysis*
Germany
Hemodynamics*
Humans
Male
Middle Aged
Models, Cardiovascular*
Predictive Value of Tests
Prognosis
Regional Blood Flow
Retrospective Studies
Risk Assessment
Risk Factors
Stress, Mechanical
Tomography, X-Ray Computed