CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 3, 1998, No 1

Influence of Aneurysm Shape on Wall Stress: a Finite Element Study

S. Uemura, D. F. Elger, D. M. Blackketter, K. H. Johansen, K. S. Kunzelman

Abstract:
Background: The risk of rupture of an abdominal aortic aneurysm (AAA) has been considered to be dependent largely on its maximum diameter (law of Laplace). We propose that, in addition, rupture risk is dependent on overall AAA shape. Methods: To evaluate this hypothesis, thin-shell finite element models of axisymmetric AAAs were created from three differently shaped meridion curves: exponential, parabola-exponential and cosine exponential. Each model had an aneurysm length of 80 mm and maximum diameter of 50 mm. An internal pressure of 18 kPa was applied. Results: The resultant hoop stresses varied according to shape, with peak values of 439, 442, and 349 kPa for the exponential, parabola-exponential, and cosine-exponential models, respectively. More importantly, the location of the peak stresses varied with shape and were not necessarily at the maximum diameter. The peak meridional stresses were lower and less variable at 184, 185, and 184 kPa for each of the models, respectively. The calculated stresses were greater than those predicted by the law of Laplace (225 and 113 for the hoop and meridion directions, respectively). Conclusion: We conclude that AAA morphology, as well as diameter, governs the risk of rupture, and that location of maximum wall stress depends on shape.

Keywords:
abdominal aortic aneurysm, risk of rupture, stress, finite element model

Address for Correspondence:

Reference:
(CVE. 1998; 3 (1): 43-47)

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