Aneurysm rupture is a life-threatening event, yet its underlying mechanisms remain largely unclear. This study investigated the fracture properties of the thoracic aneurysmatic aorta (TAA) using the symmetry-constraint Compact Tension (symconCT) test and compared results to native and enzymatic-treated porcine aortas’ tests. With age, the aortic stiffness increased, and tissues ruptured at lower fracture energy \(D\) . Patients with bicuspid aortic valves were more sensitive to age, had stronger aortas and required more \(D\) than tricuspid valves individuals (peak load: axial loading 4.42 \(\pm\) 1.56 N vs 2.51 \(\pm\) 1.60 N; circumferential loading 5.76 \(\pm\) 2.43 N vs 4.82 \(\pm\) 1.49 N. Fracture energy: axial loading 1.92 \(\pm\) 0.60 kJ m-2 vs 0.74 \(\pm\) 0.50 kJ m-2; circumferential loading 2.12 \(\pm\) 2.39 kJ m-2 vs 1.47 \(\pm\) 0.91 kJ m-2). Collagen content partly explained the variability in \(D\) , especially in bicuspid cases. Besides the primary crack, TAAs and enzymatic-treated porcine aortas displayed diffuse and shear-dominated dissection and tearing. As human tissue tests resembled enzymatic-treated porcine aortas, microstructural degeneration, including elastin loss and collagen degeneration, seems to be the main cause of TAA wall weakening. Additionally, a tortuous crack developing during the symconCT test reflected intact fracture toughening mechanisms and might characterize a healthier aorta.
