Dynamics of homemade aortic endografts: in vivo study in humans with computed tomography scanner modeling.

Background: Several cases of aortic endograft rupture have been described. In most cases, they stem from component wear and perforation of the graft, leading to leakage. Friction of the stents on the graft can cause abrasion and perforate the textile. This friction results from movements inside the endograft implanted in the aorta exposed to blood flow, arterial pressure, and the movements of the aorta itself.

Methods: To study in vivo the movements of homemade stent grafts (HMSGs) designed and constructed by the surgeons at La Pitié Salpêtrière Hospital (Paris), the displacements of the metallic skeleton of the HMSG after implantation were measured using a dynamic CT scanner connected to the patient's ECG. The geometric structure of the HMSG was modeled using MATLAB software to specify the different displacements in the HMSG: angular displacements (A) (in degrees) at the sutures between two eyelets, radial displacements (R) (in millimeters for absolute values and percentile diameter for relative values) describing HMSG pulsation, and longitudinal displacements (L) (in millimeters) reflecting compression movements. These movements differ from the global movements of the aorta in the Windkessel wave: they are movements between the different levels of eyelets in the metallic structure.

Results: The results obtained were A = 4.5 + or - 1.5 degrees , R = 0.6 + or - 0.4 mm, R% = 4.2 + or - 2.4, and L = 0.4 + or - 0.2 mm. These values are the maximum displacements measured. They are located close to the junctions between the HMSG necks and body. These transition areas between the neck anchored in the aorta and the body, which not fixed in the aneurysm pouch, seem to be the areas of the maximum displacements, mainly angular and radial. On the other parts of the HMSG, displacements were less pronounced, approaching the CT scan's detection limit (0.1 to 0.2 mm).

Conclusion: We made videos while modeling the amplitude of the displacements in the HMSG with a color code. This sequence could be a very good way to monitor the progression of HMSG displacements.