The Impact of Laser Energy Levels on In Situ Fenestrations of Aortic Stent Grafts: An On-Bench Study

(1) Background: Laser in situ fenestration (L-ISF) is an endovascular technique used to preserve target vessel patency in urgent or emergency endovascular aortic repair when fenestrated/branched solutions are unavailable or unsuitable, or as a bailout technique for fenestration or branch misalignment. This on-bench study compared different laser energy levels in five commercially available endografts to assess fabric damage and evaluate fenestration quality, dimensions, and recoil. (2) Methods: A total of 102 fenestrations were created using a 2.0 mm excimer laser catheter at low (45 mJ/mm²) or high (60 mJ/mm²) energy levels and dilated with a 6 mm plain balloon in five polyester endografts (Zenith Alpha, RelayPro, Endurant IIs, Valiant Captivia, Hercules). High-magnification microscopy assessed morphology and fabric damage after puncture, after dilation, and after 24 h. Quantitative measurements included diameters, area, and recoil under standardized study conditions. (3) Results: Valiant exhibited clearer puncture margins and no bulging; Hercules showed frequent tearing and more bulging and warp-aligned recoil at high energy. In Endurant IIs, low-energy L-ISF produced larger diameters and area but also greater recoil. RelayPro revealed stronger surface recoil with high energy. (4) Conclusion: Both low- and high-energy L-ISF were feasible across all tested grafts. A low-energy approach may be preferable for Endurant IIs, potentially reducing the risk of bridging stent graft stenosis.