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Mechanical wall stress in abdominal aortic aneurysm: Influence of diameter and asymmetry
Journal article   Open access   Peer reviewed

Mechanical wall stress in abdominal aortic aneurysm: Influence of diameter and asymmetry

David A Vorp, M.L Raghavan and Marshall W Webster
Journal of vascular surgery, Vol.27(4), pp.632-639
1998
DOI: 10.1016/S0741-5214(98)70227-7
PMID: 9576075
url
https://doi.org/10.1016/S0741-5214(98)70227-7View
Published (Version of record) Open Access

Abstract

Purpose: Risk for rupture of an abdominal aortic aneurysm is widely believed to be related to its maximum diameter. From a biomechanical standpoint, however, risk is probably more precisely related to mechanical wall stress. Many abdominal aortic aneurysms are asymmetric (for example because of anterior bulging with posterior expansion limited by the vertebral column). The purpose of this work was to investigate the effect of maximum diameter and asymmetric bulge on wall stress. Methods: Three-dimensional computer models of abdominal aortic aneurysms were generated. In one protocol, maximum diameter was held constant while bulge shape factor was varied. The shape factor took into account the asymmetric shape of the bulge. In a second protocol, the shape of the aneurysmal wall was held constant while maximum diameter was varied. Wall stress was computed in each instance with a commercial software package and assumption of physiologic intraluminal pressure. Results: Both maximum diameter and the shape factor were found to have substantial influence on the distribution of wall stress within the aneurysm. In some instances the maximum stress occurred at the midsection, and in others it occurred elsewhere. The magnitude of peak stress acting on the aneurysm increased nonlinearly with increasing maximum diameter or increasing asymmetry. Conclusions: Our computer models showed that the stress within the wall of an abdominal aortic aneurysm and possibly the potential for rupture are as dependent on aneurysm shape as they are on maximum diameter. This information may be important in determining severity of individual abdominal aortic aneurysms and in improving understanding of the natural history of the disease. (J Vasc Surg 1998;27:632-9.)

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