Mechanical Comparison between Fenestrated Endograft and Physician-Made Fenestrations.

INTRODUCTION: A fenestrated endograft (FE) is the first-line endovascular option for juxta and pararenal abdominal aortic aneurysms. A physician-modified stent-graft (PMSG) and laser in situ fenestration (LISF) have emerged to circumvent manufacturing delays, anatomic standards, and the procedure's cost raised by FE. The objective was to compare different fenestrations from a mechanical point of view.

METHODS: In total, five Zenith Cook fenestrations (Cook Medical, Bloomington, IN, USA) and five Anaconda fenestrations (Terumo Company, Inchinnan, Scotland, UK) were included in this study. Laser ISF and PMSG were created on a Cook TX2 polyethylene terephthalate (PET) cover material (Cook Medical, Bloomington, IN, USA). In total, five LISFs and fifty-five PMSG were created. All fenestrations included reached an 8 mm diameter. Radial extension tests were then performed to identify differences in the mechanical behavior between the fenestration designs. The branch pull-out force was measured to test the stability of assembling with a calibrated 8 mm branch. Fatigue tests were performed on the devices to assess the long-term outcomes of the endograft with an oversized 9 mm branch.

RESULTS: The results revealed that at over 2 mm of oversizing, the highest average radial strength was 33.4 ± 6.9 N for the Zenith Cook fenestration. The radial strength was higher with the custom-made fenestrations, including both Zenith Cook and Anaconda fenestrations (9.5 ± 4.7 N and 4.49 ± 0.28 N). The comparison between LISF and double loop PMSG highlighted a higher strength value compared with LISF (3.96 N ± 1.86 vs. 2.7 N ± 0.82; p = 0.018). The diameter of the fenestrations varied between 8 and 9 mm. As the pin caliber inserted in the fenestration was 9 mm, one could consider that all fenestrations underwent an "elastic recoil" after cycling. The largest elastic recoil was observed in the non-reinforced/OC fenestrations (40%). A 10% elastic recoil was observed with LISF.

CONCLUSION: In terms of mechanical behavior, the custom-made fenestration produced the highest results in terms of radial and branch pull-out strength. Both PMSG and LISF could be improved with the standardization of the fenestration creation protocol.