Current diameter-based guidelines are ineffective in identifying aortic aneurysms at risk to dissect. Aortic length has recently been proposed to better predict risk of dissection;​ however, the data evaluating length as a metric to predict dissection is limited and how it adds to long-standing diameter thresholds is unclear. In this thesis, ascending aortic geometry (i.e., diameter and length) and its association with normal, aneurysmal, and dissected aortic states were examined. Furthermore, mechanical properties of aortic tissue (i.e., energy loss, modulus of elasticity, and delamination strength) were also examined to determine the association between aortic geometry and mechanical risk of aortic failure. After adjusting for covariates associated with aortic length, patients who had dissection exhibited disproportionately longer aortas than normal or aneurysmal states. However, aortic length did not correlate with mechanical properties of aortic tissue associated with mechanical failure. Additional research is needed before length-based thresholds can be considered.