Long-term resistance to fracture and/or corrosion of the nitinol wires of the talent stent-graft: observations from a series of explanted devices.

The biodurability of the Nitinol wires used in stent-grafts retrieved from reoperations and autopsy was analyzed to assess the possible causes of fracture and/or corrosion of the stents. The Nitinol wires of six explanted devices presented a corrosion-free surface after in vivo service. The drawing lines in the control wires were still present, but neither burrs nor flakes were observed. Pits and crevices were rare, but some shallow ones were present. Some abrasions of the surfaces of the Nitinol wires were also observed. The chemical composition of the explanted devices showed the presence of organic contamination that covered the thick layer of titanium oxide before reaching the Nitinol itself. The durability of the Nitinol employed in the manufacture of the Talent stent-grafts was confirmed; the results of this study show the Nitinol to be resistant to corrosion. We have also concluded that the fractures of the Nitinol wires in two devices were unique adverse incidents caused by compression and bending related to the sharp angle of the Nitinol wires.

Fatigue and/or failure phenomena observed in the fabric of stent-grafts explanted after adverse events.

In this study, we aimed to investigate changes to the fabric of Talent stent-grafts following implantation of aortic endografts and to determine the possible causes of fatigue and/or failure of the grafts. Six devices were explanted at reoperation (N=5) and autopsy (N=1). Selected segments were assessed nondestructively by gross observation and destructively by analyzing textile characteristics and chemical properties. All of the devices showed a 4/4 twill woven fabric of monofilament polyester. These devices, explanted at reoperation and autopsy, presented different levels of fatigue and/or failure. Numerous holes were found in the fabric of two devices. The minor damage caused by the passage of the sutures through the weave to fasten the Nitinol wires did not progress significantly over time. The sutures remained relatively intact, except for some distortions. The main failure mode was the abrasion of the yarns at the apices of adjacent Nitinol stents. In two devices, this abrasion resulted in fraying of the yarns and holes in the fabric tubes. This short series of explanted devices provides evidence of damage to polyester fabric used in aortic endografts and raises questions regarding their resistance to abrasion and the risk of endoleak associated with monofilament fabric yarn.

The Triplex BioValsalva Prostheses To Reconstruct the Aortic Valve and the Aortic Root.

The Bentall procedure introduced in 1968 represents an undisputed cure to treat multiple pathologies involving the aortic valve and the ascending thoracic aorta. Over the years, multiple modifications have been introduced as well as a standardized approach to the operation with the goal to prevent long-term adverse events. The BioValsalva prosthesis provides a novel manner to more efficiently reconstruct the aortic valve together with the anatomy of the aortic root with the implantation of a valved conduit. This prosthesis comprises three sections: the collar supporting the valve; the skirt mimicking the Valsalva, which is suitable for the anastomoses with the coronary arteries; and the main body of the graft, which is designed to replace the ascending aorta. The BioValsalva prosthesis allows the Bentall operation to be used in patients whose aortic valve cannot be spared.

The ROVT Elan Valved Biplex Conduits for the Reconstruction of the Right Ventricular Outflow Tract.

The reconstruction of the right ventricular outflow tract (RVOT) system represents a considerable challenge for both manufacturers and surgeons because the patients requiring this type of devices have a very diverse set of anatomical challenges that can lead to complications and subsequent early device failures. We conducted an indepth investigation of a porcine-valve conduit explanted from a patient following an adverse event. A control device was analyzed as a reference. The rapid aging of the porcine valve in the right side of the heart together with major thrombus formation raises several questions. The difficulties encountered with materials used and also the design features of the conduits are once again highlighted. This group of patients continues to increase in number due to success in the surgical outcomes in early childhood. Therefore, there is a greater demand for an appropriate device. However, much work is still needed to achieve this goal, and the best approach to achieving success remains unanswered.