Prospective Assessment of the Biomechanical Properties of the Wall of an Aneurysmal-altered Abdominal Aorta According to the Results of in Vivo Ultrasound and an Associated Study of Strength Characteristics in Vitro

Patients with identified aneurysms of the abdominal aorta, who are planned for surgical treatment, undergo an ultrasound examination of the abdominal aorta to assess the elastic properties of the aortic wall using ultrasound speckle tracking. Intraoperatively, the accessible wall of the abdominal aortic aneurysm with a size of at least 10 cm2 is taken. and a section of the thrombotic cup of the aorta with a volume of up to 5 cm3. Pathologically altered tissues extracted for research are subject to removal during a standard operation for prosthetics of the infrarenal aorta and have no clinical significance for the patient.

In in vitro studies, the strength properties of the aneurysm wall are measured under uniaxial tension on a tensile testing machine, which makes it possible to evaluate the elastic properties of the test sample and obtain such parameters as Young's modulus (slope of the strain-stress diagram in a linear section at small deformations), as well as limiting strain values and loading.

The evaluation of the linearity boundaries of the surface under study, as well as the yield strength of the vascular wall and thrombotic masses, is evaluated under shear stresses using a rheometer. The tests will be carried out using special ground plane-to-plane instruments. To correlate the mechanical properties with the structural composition of the aneurysm tissue, spectral analysis of the tested tissues using the laser-induced fluorescence method and histological examination by staining the obtained sections for elastic fibers, fibrous tissues and calcification will be used.