Dissection and 3D reconstruction of healthy and aneurysmal human ascending thoracic aorta

Ascending thoracic aortic aneurysm (ATAA) is among the most devastating forms of cardiovascular disease, causing a significant mortality despite current medical and surgical treatments [1]. This form of disease is a predisposing factor for spontaneous aortic dissection which in general results in the initiation of an intimal flap and its propagation due to blood flow. Since aortic dissection fails by separation of the elastic layers [2], the delamination strength of ATAA tissues was investigated by designing and performing mechanical tests that simulate the in-vivo tearing condition of the aortic wall. Specifically, the delamination tests were carried out on nonaneurysmal and aneurysmal human ascending thoracic tissues with bicuspid (BAV) and tricuspid (TAV) aortic valves. The influence of the anisotropy on these properties was investigated by testing oriented specimen strips which morphology was studied with SEM. Thus imaging techniques and 3D reconstruction software were used to obtain the 3D shape of ATAAs for estimating the wall stress distribution in future investigations. On the basis of a methodology developed in our laboratory [3], the geometry of ATAAs was reconstructed for patients routinely undergoing imaging analysis prior to surgical repair. Surfaces corresponding to the aortic wall were created with segmentation and smoothing techniques to yield virtual aneurysms ready for finite element analyses. Preliminary results suggest that ATAAs have lower delamination strength than the nonaneurysmal tissues indicating a risk of aortic dissection and that the 3D geometry of ATAAs can be successfully reconstructed from the MRI and CT imaging analyses