Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 Jun;36(6):921-32.
doi: 10.1007/s10439-008-9490-3. Epub 2008 Apr 9.

The effects of anisotropy on the stress analyses of patient-specific abdominal aortic aneurysms

Jonathan P Vande Geest  1 , David E Schmidt, Michael S Sacks, David A Vorp
Affiliations

The effects of anisotropy on the stress analyses of patient-specific abdominal aortic aneurysms

Jonathan P Vande Geest et al. Ann Biomed Eng. 2008 Jun.

Abstract

The local dilation of the infrarenal abdominal aorta, termed an abdominal aortic aneurysm (AAA), is often times asymptomatic and may eventually result in rupture-an event associated with a significant mortality rate. The estimation of in-vivo stresses within AAAs has been proposed as a useful tool to predict the likelihood of rupture. For the current work, a previously-derived anisotropic relation for the AAA wall was implemented into patient-specific finite element simulations of AAA. There were 35 AAAs simulated in the current work which were broken up into three groups: elective repairs (n = 21), non-ruptured repairs (n = 5), and ruptured repairs (n = 9). Peak stresses and strains were compared using the anisotropic and isotropic constitutive relations. There were significant increases in peak stress when using the anisotropic relationship (p < 0.001), even in the absence of the ILT (p = 0.014). Ruptured AAAs resulted in elevated peak stresses as compared to non-ruptured AAAs when using both the isotropic and anisotropic simulations, however these comparisons did not reach significance (p(ani) = 0.55, p(iso) = 0.73). While neither the isotropic or anisotropic simulations were able to significantly discriminate ruptured vs. non-ruptured AAAs, the lower p-value when using the anisotropic model suggests including it into patient-specific AAAs may help better identify AAAs at high risk.

PubMed Disclaimer

Figures

FIGURE 1
FIGURE 1
(a) 3D spline defining centerpoint of each longitudnal slice of elements. (b) Definition of local material coordinates.
FIGURE 2
FIGURE 2
Circumferential (a) and longitudinal (b) Cauchy stress vs. stretch ratio for the PT ISO and PT ANI simulations and the corresponding biaxial experimental data.
FIGURE 3
FIGURE 3
(a) The strain values at t = 60 kPa and (b) TM for 14 biaxial simulations. AVE ISOTROPIC simulations utilize the uniaxially-derived isotropic model previously reported by Raghavan et al.
FIGURE 4
FIGURE 4
(Top) Percent change in peak maximum principal stress when using the anisotropic constitutive model for the AAA wall. Differences were investigated both with and without ILT present. (Bottom) Percent change in maximum principal strains when using the anisotropic model.
FIGURE 5
FIGURE 5
Maximum principal stress distributions for AAA17. ANI = anisotropic AAA wall; ISO = isotropic AAA wall; ANINOILT = anisotropic wall no ILT; ISONOILT = isotropic wall with no ILT.
FIGURE 6
FIGURE 6
Maximum principal stress distributions for N5 and R7.
FIGURE 7
FIGURE 7
Comparison of anisotropic and isotropic simulations for ruptured and non-ruptured groups.
See this image and copyright information in PMC

References

    1. Chuong CJ, Fung YC. On residual stresses in arteries. J Biomech Eng. 1986;108(2):189–192. [erratum appears in J. Biomech. Eng. 1990 Aug;112(3):249] - PubMed
    1. Crawford CM, Hurtgen-Grace K, et al. Abdominal aortic aneurysm: an illustrated narrative review. J Manipulative Physiol Ther. 2003;26(3):184–195. - PubMed
    1. Delfino A, Stergiopulos N, et al. Residual strain effects on the stress field in a thick wall finite element model of the human carotid bifurcation. J Biomech. 1997;30(8):777–786. - PubMed
    1. Di Martino ES, Guadagni G, et al. Fluid-structure interaction within realistic three-dimensional models of the aneurysmatic aorta as a guidance to assess the risk of rupture of the aneurysm. Med Eng Phys. 2001;23(9):647–655. - PubMed
    1. Di Martino E, Vorp D. Effect of variation in intraluminal thrombus constitutive properties on abdominal aortic aneurysm wall stress. Ann Biomed Eng. 2003;31(7):804–809. - PubMed

Publication types