Annals of Biomedical Engineering

, Volume 27, Issue 4, pp 469–479 | Cite as

In Vivo Three-Dimensional Surface Geometry of Abdominal Aortic Aneurysms

  • Michael S. Sacks
  • David A. Vorp
  • M. L. Raghavan
  • Michael P. Federle
  • Marshall W. Webster
Article

Abstract

Abdominal aortic aneurysm (AAA) is a local, progressive dilation of the distal aorta that risks rupture until treated. Using the law of Laplace, in vivo assessment of AAA surface geometry could identify regions of high wall tensions as well as provide critical dimensional and shape data for customized endoluminal stent grafts. In this study, six patients with AAA underwent spiral computed tomography imaging and the inner wall of each AAA was identified, digitized, and reconstructed. A biquadric surface patch technique was used to compute the local principal curvatures, which required no assumptions regarding axisymmetry or other shape characteristics of the AAA surface. The spatial distribution of AAA principal curvatures demonstrated substantial axial asymmetry, and included adjacent elliptical and hyperbolic regions. To determine how much the curvature spatial distributions were dependent on tortuosity versus bulging, the effects of AAA tortuosity were removed from the three-dimensional (3D) reconstructions by aligning the centroids of each digitized contour to the z axis. The spatial distribution of principal curvatures of the modified 3D reconstructions were found to be largely axisymmetric, suggesting that much of the surface geometric asymmetry is due to AAA bending. On average, AAA surface area increased by 56% and abdominal aortic length increased by 27% over those for the normal aorta. Our results indicate that AAA surface geometry is highly complex and cannot be simulated by simple axisymmetric models, and suggests an equally complex wall stress distribution. © 1999 Biomedical Engineering Society.

PAC99: 8719Rr, 8759Fm, 8757Gg

Abdominal aortic aneurysm Curvature Tortuosity Three-dimensional reconstruction 

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REFERENCES

  1. 1.
    Ahn, S., D. Eton, and K. Hodgson. Current concepts in endovascular surgery. In: Medical Intelligence Unit. Austin: R. G. Landes, 1994, p. 128.Google Scholar
  2. 2.
    Darling, R., C. Messina, D. Brewster, and L. Ottinger. Autopsy study of unoperated abdominal aortic aneurysms. J. Vasc. Surg. 56:161–164, 1977.Google Scholar
  3. 3.
    Dobrin, P. Pathophysiology and pathogenesis of aortic aneurysms. Surg. Clin. North Am. 69:687–703, 1989.Google Scholar
  4. 4.
    Elger, D. F., D. M. Blackketter, R. S. Budwig, and K. H. Johansen. The influence of shape on the stresses in model abdominal aortic aneurysms. J. Biomech. Eng. 118:326–332, 1996.Google Scholar
  5. 5.
    Flugge, W. Tensor Analysis and Continuum Mechanics. New York: Springer-Verlag, 1972, p. 207.Google Scholar
  6. 6.
    Hollier, L., L. Taylor, and J. Ochsner. Recommended indication for operative treatment of abdominal aortic aneurysms. J. Vasc. Surg. 15:1046–1056, 1992.Google Scholar
  7. 7.
    Inzoli, F., F. Boschetti, M. Zappa, T. Longo, and R. Fumero. Biomechanical factors in abdominal aortic aneurysm rupture. Eur. J. Vasc. Surg. 7:667–674, 1993.Google Scholar
  8. 8.
    Mower, W., L. Baraff, and J. Sneyd. Stress distributions in vascular aneurysms: Factors affecting risk of aneurysm rupture. J. Surg. Res. 55:155–161, 1993.Google Scholar
  9. 9.
    Parodi, J., F. Criado, H. Barone, C. Schonholz, and L. Queral. Endoluminal aortic aneurysm repair using a balloonexpandable stent-graft device: A progress report. Ann. Vas. Surg. 8:523–529, 1994.Google Scholar
  10. 10.
    Sacks, M. S., C. J. Chuong, G. H. Templeton, and R. Peshock. In vivo 3D reconstruction and geometric characterization of the right ventricular free wall. Ann. Biomed. Eng. 21:263–275, 1993.Google Scholar
  11. 11.
    Smith, D., M. Sacks, P. Pattany, and R. Schroeder. Fatigue induced changes in bioprosthestic heart valve 3D geometry and the relation to tissue damage. J. Heart Valve Dis. 8:25–33, 1999.Google Scholar
  12. 12.
    Smith, D., M. Sacks, M. Raghavan, M. Federle, M. Webster, and D. Vorp. A biquintic hermite finite element for surface geometric analysis of abdominal aortic aneurysms. In: Third World Congress on Biomechanics, Hokaiddo, Japan, 1998.Google Scholar
  13. 13.
    Smith, D. B., M. S. Sacks, P. M. Pattany, and R. Schroeder. High-resolution magnetic resonance imaging to characterize the geometry of fatigued porcine bioprosthetic heart valves. J. Heart Valve Dis. 6:424–432, 1997.Google Scholar
  14. 14.
    Stringfellow, M., P. Lawrence, and R. Stringfellow. The influence of aorta-aneurysm geometry upon stress in the aneurysm wall. J. Surg. Res. 42:425–433, 1987.Google Scholar
  15. 15.
    Struik, D. J. Lectures on Classical Differential Geometry, 2nd ed. New York: Dover, 1961, p. 232.Google Scholar
  16. 16.
    Vorp, D., M. Raghavan, and M. Webster. Mechanical wall stress in abdominal aortic aneurysm: Influence of diameter and asymmetry. J. Vasc. Surg. 27:632–639, 1998.Google Scholar
  17. 17.
    Wolf, Y. G., and E. F. Bernstein. A current perspective on the natural history of abdominal aortic aneurysms. Cardiovasc. Surg. 2:16–22, 1994.Google Scholar

Copyright information

© Biomedical Engineering Society 1999

Authors and Affiliations

  • Michael S. Sacks
    • 1
  • David A. Vorp
    • 1
    • 2
    • 3
  • M. L. Raghavan
    • 1
  • Michael P. Federle
    • 4
  • Marshall W. Webster
    • 2
  1. 1.Department of BioengineeringUniversity of PittsburghPittsburgh
  2. 2.Department of SurgeryUniversity of PittsburghPittsburgh
  3. 3.Department of Mechanical EngineeringUniversity of PittsburghPittsburgh
  4. 4.Department of RadiologyUniversity of PittsburghPittsburgh

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