Experimental In Situ Laser Fenestration Creates Immediate Substantial Textile Damages

Introduction - Commercially available fenestrated and branched endografts (FBE) using reinforced nitinol ring fenestrations represent the endovascular treatment of choice for thoraco-abdominal aortic aneurysm (TAAA). In situ laser fenestration (INLF) emerges as an innovative and immediately available alternative, which could be less deleterious than mechanical in situ fenestration. However, biomechanical features of INLF are poorly known. Therefore, the aim of this study was to experimentally evaluate the textile damages secondary to INLF. Methods - In a first step, an in vitro bench study consisted in a microscopic textile analysis of textile damages following INLF with various standard endografts. We compared INLF to mechanical fenestration using an 18G needle in two clinical scenarios (with or without tension applied to the fabric, corresponding to a 90mmHg blood pressure). The subsequent hole was dilated using a non-compliant balloon followed by a cutting balloon and stabilized by a balloon-expandable covered stent. Tear and burst strength tests were performed to determine the loss of textile mechanical strength. Leak tests at the stent-fenestration junctions were implemented using a water column. In a second step, an in vivo study evaluating the feasibility and the damages secondary to INLF was performed at the level of the thoraco-abdominal aorta in sheep. Results - In total, 24 stent-graft textile samples (8 Cook, 8 Medtronic and 8 Vascutek) were analyzed in vitro. Primary fenestrated holes morphology differed between mechanical and INLF with all types of textiles, in both clinical scenarios. Following mechanical fenestration, the hole created, resulted in spacing fabric filaments whereas one circular with cauterized edges were observed after INLF. Tear and burst strength tests results, highlighted a 26±4% textile mechanical strength loss after in situ fenestration. A non-significant decrease of 7% of mechanical resistance was observed following INLF compared to mechanical fenestration (p=0.21). For each in situ fenestration technique, a substantial leak rate persisted at the stent-fenestration junction, even after ballooning. This was found both in in vitro and in vivo analyses. Regarding the in vivo study, 14 INLF were performed in 10 sheep using the Vascutek Anaconda, the Cook Zenith Alpha, the Medtronic Endurant II and the Gore Excluder stent-graft textiles in 4, 3, 2 and 1 cases respectively. Technical success of INLF was 80% but all INLF had a