Mechanical failure of prosthetic human implants: A 10-year experience with aortic stent graft devices

Objective: The first endovascular stent graft was implanted to treat an abdominal aortic aneurysm more than a decade ago. This technique has evolved dramatically with the growing understanding of metallurgic and fabric sciences and improved device designs. However the potential for stent graft material failure remains. This investigation describes the incidence of material failure, potential modes of device fatigue, and the clinical significance of these failures. Methods. Six hundred eighty-six endovascular stent grafts were used to treat patients with aortic aneurysms. Device fatigue in the form of stent, suture fracture, or graft wear was identified with an analysis of follow-up radiographs and explanted stent grafts. A review of patient clinical histories, spiral computed tomographic scan studies, scanning electron microscopy, and energy dispersion spectroscopy of explanted devices was conducted to evaluate the modes and consequences of failure. Results. Sixty patients were identified with device fatigue, 49 of whom had abdominal endovascular repairs and I I of whom had thoracic repairs. Of the 60 patients with stent graft fatigue, 43 patients had metallic stent fractures, 14 had suture disruptions, and three had graft holes. These material failures occurred within seven distinct stent graft designs. The average time to the recognition of failure was 19 months, with a mean follow-up period of 8 months since the event was identified. Eleven patients died, and one was lost to follow-up 2 years after identification of a stent fracture. The remaining patients are presently being followed eoyj physical examination, plain film radiograph, and computed tomographic scans for clinical sequelae of device fatigue. Conclusion: Endovascular stent graft fatigue has been recognized in numerous devices after aortic implantation. Fatigue may take the form of stent, graft, or suture failure, with certain modes unique to specific stent graft devices. The clinical significance of stent graft material failure remains uncertain.