Since the introduction of endovascular prostheses by Parodi in the 80’s, Nitinol wires and stents became very popular. This shape memory alloy is used in all commercially available devices but the Zenith (Cook) and the Life-Path (Edwards). Nitnol did not prove to be sufficiently resistant to corrosion in most devices. We hereby report observations on control specimens, animal explants and human explants harvested at reoperation or necropsy.

Control specimens: wires from Vanguard (Boston Scientific), Anaconda (Vascutek Terumo), Talent (Medtronic AVE) and stents from AneuRx (Medtronic AVE).

Animal explants: two series of dogs fitted with the Vanguard (Boston Scientific) whose Nitinol wire was exposed to blood flow and the Anaconda (Vascutek Terumo) whose Nitinol wire is sewn on the external side of the textile tube.

Human explants: devices whose Nitinol is not in contact with the blood flow i.e. Hemobahn and Excluder (WLGore) and AneuRx and Talent (Medtronic AVE); several Vanguard devices (Boston Scientific) with Nitinol wire exposed to the blood flow.

Observations showed processing of Nitinol wires to give specific shapes impacts resistance to pitting. In addition, laser cutting of stents proved to be deleterious with the formation of fissures. These phenomena are amplified in vivo. Despite similar chemical composition in all the wires, observations of pitting after implantation differ dramatically from one specimen to another. The exposure of wires to the blood flow is important.

Nitinol must be considered a material of choice to support endovascular devices; therefore, we must develop new processes to fully prevent corrosion, particularly pitting.