Biomechanical Properties of the Aortic Root Are Distinct from Those of the Ascending Aorta in Both Normal and Aneurysmal States

This study performed a comprehensive biomechanical comparison of human aortic root and ascending aortic tissue in both normal and aneurysmal states to determine whether these anatomically distinct regions exhibit different mechanical behaviors. Using ex vivo human tissue, the authors quantified stiffness, energy dissipation, and resistance to interlamellar separation. The aortic root exhibited greater viscoelastic energy loss and higher delamination strength than the ascending aorta in the normal state. In aneurysmal tissue, delamination strength was significantly reduced in both regions, but only the ascending aorta showed concurrent increases in stiffness and energy loss. Aging and hypertension were strongly associated with reduced aortic root strength, whereas aortic diameter was not. These findings demonstrate that aortic root biomechanics are distinct from those of the ascending aorta and suggest that region-specific mechanical parameters may be required for improved aneurysm risk assessment.