Abstract
To investigate microscopic dynamics of aortic rupture, we developed a device which enables to observe the dynamics with a microscope equipped with an equibiaxial tensile test system. A metal cylinder 6 and 8 mm in inner and outer diameter, respectively, was placed above the center of a thin-sliced specimen held with a circular metal frame 10 mm in inner diameter. The frame was vertically elevated until specimen rupture while measuring force loaded on the frame and taking images of the specimen. Stress and strain were measured from the force and the displacement of the markers on the surface of the specimen, respectively. Silicone rubber was stretched until rupture as an example of homogeneous isotropic material. Images of the specimen during the test were clearly observed through the cylinder. Elastic modulus of the silicone was obtained to be 1.9 MPa, which was comparable to a typical value of the material. The coefficient of variation of strains was 3%. We then applied this test system to specimens obtained from the porcine thoracic aortas. Stress at strain of 0.5 and tensile strength were comparable to those reported previously. The coefficient of variation of strain in the aortic specimen was 7%, and was significantly larger than that of silicone rubber, indicating that the aortic specimens are inhomogeneous. The developed device could provide reliable mechanical properties and was useful for observing specimen under microscope in an equibiaxial state.
