Rupture properties of aneurysmal aortic roots

Aortic root aneurysms have a high potential to rupture even in young patients with small aneurysm diameters. Our objective was to study the mechanical properties of aneurysmal sinus wall. Tissues were removed from six patients with non-ruptured aneurysms. The left, right, and non-coronary sinuses were obtained and cut in dogbone-shaped strips, which were submitted to simple elongation until failure. As mechanical indices, failure stress, failure strain, and peak elastic modulus were calculated. In the majority of tests, the inner layers of sinus wall ruptured first, indicating heterogeneity across wall thickness. Regional differences were detected among the three sinuses, but these were not statistically significant. No directional differences were detected in the left and right, whereas in the non-coronary sinus failure stress and peak elastic modulus were higher in the circumferential direction. The present observations should be considered with wall stress predictions by finite element analyses, offering insight to the mechanism of sinus wall failure, as well as for the development of improved prosthetic materials for aortic root replacement.