An experimental and numerical comparison of the rupture locations of an abdominal aortic aneurysm.
OBJECTIVE
To identify the rupture locations of idealized physical models of abdominal aortic aneurysm (AAA) using an in-vitro setup and to compare the findings to those predicted numerically.


METHODS
Five idealized AAAs were manufactured using Sylgard 184 silicone rubber, which had been mechanically characterized from tensile tests, tear tests, and finite element analysis. The models were then inflated to the point of rupture and recorded using a high-speed camera. Numerical modeling attempted to confirm these rupture locations. Regional variations in wall thickness of the silicone models was also quantified and applied to numerical models.


RESULTS
Four of the 5 models tested ruptured at inflection points in the proximal and distal regions of the aneurysm sac and not at regions of maximum diameter. These findings agree with high stress regions computed numerically. Wall stress appears to be independent of wall thickness, with high stress occurring at regions of inflection regardless of wall thickness variations.


CONCLUSIONS
According to these experimental and numerical findings, AAAs experience higher stresses at regions of inflection compared to regions of maximum diameter. Ruptures of the idealized silicone models occurred predominantly at the inflection points, as numerically predicted. Regions of inflection can be easily identified from basic 3-dimensional reconstruction; as ruptures appear to occur at inflection points, these findings may provide a useful insight into the clinical significance of inflection regions. This approach will be applied to patient-specific models in a future study.
Doyle
Barry J
BJ
Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical and Aeronautical Engineering, and the Materials and Surface Science Institute, University of Limerick, Ireland.
Corbett
Timothy J
TJ
Callanan
Anthony
A
Walsh
Michael T
MT
Vorp
David A
DA
McGloughlin
Timothy M
TM
D017542:Aneurysm, Ruptured / Q000209:etiology* / Q000473:pathology*; D017544:Aortic Aneurysm, Abdominal / Q000150:complications* / Q000473:pathology*; D020342:Finite Element Analysis; D006801:Humans; D008955:Models, Cardiovascular; D009716:Numerical Analysis, Computer-Assisted; D015203:Reproducibility of Results; D012828:Silicones; D013314:Stress, Mechanical; D013718:Tensile Strength
D012828:Silicones