Dissection properties and mechanical strength of tissue components in human carotid bifurcations |
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Authors: | Tong Jianhua Sommer Gerhard Regitnig Peter Holzapfel Gerhard A |
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Institution: | (1) Institute of Biomechanics, Center of Biomedical Engineering, Graz University of Technology, Kronesgasse 5-I, 8010 Graz, Austria;(2) Institute of Pathology, Medical University Graz, Graz, Austria;(3) Department of Solid Mechanics, Royal Institute of Technology (KTH), Stockholm, Sweden; |
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Abstract: | Carotid artery dissections can be triggered by several factors. The underlying biomechanical phenomena and properties are
unclear. This study investigates the dissection properties of 62 human carotid bifurcations using two experimental methods:
direct tension and peeling tests. Direct tension tests study the mechanical strength of the tissue components in radial direction,
while peeling tests quantify the fracture energy required to propagate a dissection in a tissue. Results show that the interface
between the healthy adventitia and media has the highest radial failure stress (132 ± 20 kPa, mean ± SD, n = 25), whereas the lowest value occurs between the diseased intima and media (104 ± 24 kPa, n = 18). The radial tissue strength at the bifurcation is the highest compared with locations that are away from the central
region of the bifurcation. Force/width values required to separate the individual layers and to dissect the media in the circumferential
direction are always lower than related values in the axial direction, suggesting anisotropic dissection properties. Dissection
energies per reference area generated during the peeling tests are also lower for strips in the circumferential direction
than for axial strips, and they vary significantly with the location, as shown for the media. Histological investigations
demonstrate that interfacial ruptures mainly occur in the media in both types of tests and are 2-5 elastic lamellae away from
the external and internal elastic laminae. A remarkably “rougher” dissection surface is generated during axial peeling tests
when compared with tests performed in the circumferential direction. |
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