Michigan State University MSU Engineering Mechanical Engineering

Characterization of Heterogeneous Mechanical Properties of Aorta

Jungsil Kim

Summary of Research

The aorta is the main artery and plays an important role in the blood circulatory system. Diseases of the aorta such as aortic aneurysm and aortic dissection cause a high mortality rate and, hence, the study of the mechanical properties of the aorta has been an active research area. In many previous studies, the aorta has been considered as a straight cylindrical tube undergoing uniform circumferential deformation and therefore uniform strain/stress distribution in the circumferential direction. However, recent biomedical imaging studies show that the aorta has circumferentially nonuniform deformation during the cardiac cycle and the aortic wall distends asymmetrically. Furthermore, it has been shown that the anterior wall displacement is larger than the posterior wall displacement. These in vivo studies have raised yet another question whether the nonuniform deformation is due to the inhomogeneous properties of the aortic wall or due to the surrounding tissues. The purpose of this study is to develop an ex vivo experiment and the strain analysis for characterizing the local strain of the aorta by using 3D reconstructed particle tracking algorithm and to investigate regional variations of the local strain in the porcine aorta during the inflation test.

Specimen Preparation

Thoracic Aortas from about 6 month old pigs weighing approximately 90 kg
(stored in a refrigerator at 5°C until used)
  1. Remove loose connective tissue and adipose tissues of the aorta.
  2. Ligate all branches with thread.
  3. Fix both ends of the specimen to cannulas.
  4. Attach 550 µm diameter spheres on the surface of the specimen.
  5. Mount the specimen on the test chamber

Image Processing

Selected publications:

J. Kim, S. Baek, Circumferential variations of mechanical behavior of the porcine thoracic aorta during the inflation test, Journal of Biomechanics, vol. 44, 1941-1947, 2011

J. Kim, J.-W. Hong, S. Baek, Longitudinal differences in the mechanical properties of the thoracic aorta depend on circumferential regions, submitted

J. Kim, B.K. Peruski, S.C. Hunley, S.T. Kwon, S. Baek, Influence of surrounding tissues on biomechanics of aortic wall, submitted

J. Kim, J.-W. Hong, S. Baek, Regionally varying, anisotropic constitutive relations of mechanical behavior of porcine thoracic aortic walls, in preparation

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