Experimental assessment of proximal stent-graft (InterVascular™) fixation in human cadaveric infrarenal aortas

Objectives: this paper investigates the radial deformation load of an aortic endoluminal prosthesis and determines the longitudinal load required to cause migration in a human cadaveric aorta of the endoprosthesis. Design and methods: the endovascular prosthesis under investigation was a 24 mm diameter, nitinol, self-expanding aortoaortic device (InterVascular; Clearwater, Florida, U.S.A.). Initially, a motorised digital force gauge developed an incremental load which was applied to the ends of five stent-grafts, to a maximum of 10 mm (42%) compression. Secondly, using a simple bench model, each end of four stent-grafts were deployed into 20 cadaveric experimental aneurysm necks and a longitudinal load applied to effect distraction. Results: increasing load produced increasing percentage deformation of the stent-grafts. The mean longitudinal distraction load for an aneurysm neck of 20 mm was 409 g (200-480 g), for 25 mm was 277 g (130-410 g) and for 10 mm was 218 g (130-340 g). The aneurysm diameter and aortic calcification had p values of 0.002 and 0.047 respectively, while the p value for aneurysm neck length was less than 0.00001. Conclusions: these results suggest that there is a theoretical advantage of oversizing an aortic prosthesis and that sufficient anchorage is achieved in an aortic neck of 10 mm to prevent migration when fully deployed.