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

Clinical examples of fatigue in Talent endovascular system. A, After persistent type I endoleak, 70-year-old man had endovascular graft explanted and conventional repair completed. Explanted graft showed signs of graft wear with frayed fabric yarns and creation of defined hole (arrow). B, Proximal longitudinal bar fracture in Talent endovascular graft (arrow). C, Distal aortic longitudinal bar fracture (arrow). D, Ipsilateral limb longitudinal bar fracture in Talent endovascular graft. E, Midbody z stent fracture (arrow). F, Proximal transrenal stent fracture in Talent endovascular graft. Note fracture has occurred adjacent to site of nitinol wire crimp, which contains two ends of z-configured stent.

Clinical examples of fatigue in Boston Scientific Vanguard endovascular graft. Sixty-nine-year-old man had tube graft inserted for repair of abdominal aortic aneurysm. A, Proximal row separation was defined on this graft along with distal endoleak caused by retraction of prosthesis. B, Graft was explanted, and conventional repair was done at 36 months. Arrow points to site of proximal row separation. C, High-powered magnification of graft depicted in Fig 9, B, shows fabric fatigue and wear holes on prosthesis surface. D, Seventy-nine-year-old man had endovascular tube graft placed for repair of abdominal aortic aneurysm. On surveillance abdominal radiographs, suture fractures in body of graft are detected (arrow). This patient remains in surveillance program.

Attachment system of EVT endovascular grafting system. Note fracture of hook shank at site of its laser weld on z-configured attachment system (arrow).

Palmaz balloon expandable proximal stent attachment device of handmade Parodi-Palmaz system. Note fracture of proximal diamond row (arrow).

Abdominal radiograph of patient who underwent AneuRx endografting of abdominal aortic aneurysm. Arrow denotes site of fracture in one of nitinol rings on stent strut.

High-resolution explant radiograph of Gore TAG stent graft that was used to repair thoracic aortic aneurysm. This patient was seen 32 months after endovascular repair of thoracic aneurysm with new endoleak. Endoprosthesis was explanted, and conventional reconstruction was successfully accomplished. Explanted examination of stent graft with plain film radiograph shows z-configured wire fractures (arrowheads) and longitudinal bar fracture (arrow).

SEM of explanted endovascular grafts for abdominal aortic aneurysm. A, Vanguard endovascular graft has platinum wire wound around proximal and distal portions of attachment system to improve radiograph visualization (40×). B, Despite suspected increased potential for metal fatigue and corrosion at interface of these two metals, no such fatigue was found in nitinol in this 36-month-old implant (200×). C, SEM of Talent stent explanted 15 months after insertion. Site depicts crimped region of two ends of metal bar. No significant wear or pitting was detected on surface of nitinol stent at this presumably high risk area for fatigue (40×). D, High-powered (4K) magnification of surface of Talent nitinol spring after explantation. Rough-appearing, uniform oxide layer is discerned.

EDS of explanted Talent graft. A, Marked decrease in nickel peak is discerned in area containing defect in relatively uniform oxide layer. B, In subjacent region to that irregular area described in A, normal titanium to nickel distribution is identified.

Free surface of a fractured nitinol wire from Gore TAG supporting stent explanted 32 months after thoracic aortic aneurysm repair. Note cleavage planes and irregular surface at step-off point of this fatigue fracture (200×).