Abstract
OBJECTIVE: The physical impact of the application of Heli-FX EndoAnchors (EA; Medtronic, Minneapolis, USA) on endograft (EG) material is unclear. This study aimed to examine the possible EG membrane alterations after EA implantation. METHODS: Heli-FX EndoAnchors were applied in vitro into four aortic endocuffs: AFX2 (Endologix Inc., Irvine, USA); Endurant II (Medtronic, Minneapolis, USA); Gore Excluder (W.L. Gore and Assoc., Flagstaff, USA); and Zenith Renu (Cook Aortic Interventions, Bloomington, USA). Two of these, Endurant II and Renu, are made of polyethylene terephthalate (PET), while Excluder and AFX2 are made of expanded polytetrafluoroethylene (ePTFE). The penetration angle was measured for each EA. The EAs were then carefully removed, and perforations examined with digital and fluorescent microscopy. The area and perimeter of the holes were digitally calculated, and material alterations were analysed. RESULTS: Of the 13 EAs applied, 12 remained in place. The mean penetration angle was 79°. The ePTFE perforations had oval openings, while PET perforations were round. After EA removal, comparisons between ePTFE and PET material perforations suggested a larger hole area (p = 0.011) and perimeter (p = 0.003) in the former. The ePTFE perforations in the AFX2 were the largest compared with the holes in other endocuffs (p = 0.050). The perforation channel of the ePTFE membrane of the Excluder cuff retained its form after EA removal. Local dissection like layer damage extended further. The perforations in both the Endurant II and the Renu endocuffs shared similar characteristics, with multiple fibres of PET elongated, distorted, or ruptured. CONCLUSION: During EA placement, the EG membrane undergoes local alteration and or destruction. Expanded PTFE, particularly AFX2 endocuffs (for which EA use is not recommended), are characterised by a more extensive degree of material alteration compared with PET. Additional studies are required to chronologically supplement these findings in fatigue tests.