The layer-specific biomechanical properties of dissecting ascending aortic aneurysm (Stanford type A of dissection)

The aims of this paper was the analysis of the mechanical properties of dissected wall of the ascending aortic aneurysm (n = 12). Methods: All aortas were collected from men (mean age: 48 ± 12 years, mean diameter of the aneurysm: 49 mm ± 4 mm). The mechanical properties were determined based on directional tensile test. The biomechanical assay was complemented by conducting histological analysis (hematoxylin and eosin, Mallory’s trichrome, Azan stain). Results: The highest values (median) of failure Cauchy stress, failure force, Young’s modulus and stiffness coefficient were obtained for the adventitia (max = 1.40 MPa, Fmax = 4.05 N, E = 26.11 MPa, k = 1.06 N/mm). Conclusions: The results indicate that the mechanical function of the adventitia in healthy tissue and dissected ascending aorta aneurysm is the same, i.e., it protects the vessel against destruction. The failure Cauchy stresses found in the media and intima are comparable and amounted to 0.23 and 0.21 MPa, respectively. The results indicate that dissection affects the mechanical properties of ascending aorta wall layers. The mechanical loads are probably transferred within the dissected aneurysmal wall not only through the media, but also through the intima.