Graft Durability and Fatigue after In Situ Fenestration of Endovascular Stent Grafts Using Radiofrequency Puncture and Balloon Dilatation

ObjectivesIn situ fenestration of endovascular stent grafts is a technique that is becoming more common, as it has the advantages of decreased cost, increased availability, and more anatomic configuration than other methods of branch revascularization. However, a significant concern is the short- and long-term durability of the stent graft fabric during and after fenestration.MethodsThis study utilizes the textiles analysis techniques of macro- and microscopic imaging, tear strength testing, burst strength testing, and accelerated cyclic fatigue testing on the fabrics of the Cook Zenith, Medtronic Talent, and Medtronic Endurant stent grafts (three polyester grafts), as well as two different expanded polytetrafluoroethylene (ePTFE) membranes. Specimens were punctured using radiofrequency, and serially dilated with angioplasty balloons (3, 5, and 7 mm). For each type of fabric, three groups were analyzed: control, radiofrequency (RF) puncture only, and balloon dilated.ResultsA total of 110 specimens were analyzed, with 80 of them having been fenestrated. The Zenith fabric had the greatest strength after fenestration, but was limited by the inability to fully dilate the fenestration with the conventional balloons, which only achieved 26-29% of their nominal balloon diameter. While the Talent and Endurant grafts could be dilated with balloons, the orifices were markedly elliptical not circular. After accelerated fatigue testing, there was an increase in the size of fenestrations of the Talent fabric. There was no increase in fenestration size for the Endurant fabric, Zenith fabric, or the ePTFE fabrics, after fatigue testing.ConclusionsWhile the Zenith fabric was the strongest both before and after fenestration, it requires further study with cutting balloons to achieve full-sized fenestrations. All fenestrations remained stable during fatigue testing except for the Talent fabric. This study serves as the baseline for future studies that will include stent grafts, branch stents, and cutting balloons.