Effect of Endostaple Configuration and Oversizing on Endograft Displacement Force: An In Vitro Evaluation of the Aortoseal Endostapling System

Proximal endograft fixation remains a key determinant of long-term durability of endovascular aortic repair (EVAR). The Aortoseal Endostapling system consists of a nitinol frame with 6 welded endostaples at the proximal end, intended to enhance fixation and seal of an endograft by mimicking the hand-sewn anastomosis of open aortic repair. This study evaluates the effect of different distributions of activated endostaples on endograft displacement force (EDF), while considering various endograft oversizing options.

An in vitro silicone tube model was used to assess EDF at 2 mm endograft displacement and pull-out force across 11 activated staple configurations of the Aortoseal Endostapling system with 10%, 20%, and 30% endograft oversizing. Interobserver agreement was assessed using the intraclass correlation coefficient (ICC), based on a 2-way mixed-effects model for absolute agreement.

Intraclass correlation coefficient for interobserver agreement was 0.987. Endograft displacement force ranged from 8.8 N ± 0.15 N to 39.6 N ± 2.96 N across all configurations and oversizing conditions. Incorporation of the Aortoseal frame alone, without staple activation, substantially increased EDF compared with no Aortoseal frame at 10% and 20% oversizing. Furthermore, EDF was mostly influenced by the number of activated staples and the maximum unstapled circumferential angle (MUCA). The 6-activated-staple configuration consistently yielded the highest EDF. The effect of oversizing on EDF was inconsistent across configurations at 10% and 20%, whereas 30% oversizing was associated with lower EDF in most configurations. Pull-out force exceeded EDF in all tested configurations except the 1-activated-staple configuration.

In this in vitro study, Aortoseal frame incorporation alone substantially increased EDF relative to the graft-only configuration at 10% and 20% oversizing. Ten percent endograft oversizing yielded EDF values comparable with 20% oversizing across most configurations. Circumferential staple distribution was the primary determinant of EDF in the Aortoseal Endostapling system, with EDF decreasing with increasing MUCA and increasing with staple number across all endograft oversizing conditions, consistent with circumferential load sharing as a potential underlying mechanism. These findings may serve as a mechanistic reference framework for preoperative planning in anatomically challenging cases and warrant further experimental and clinical evaluation.Clinical ImpactThe Aortoseal Endostapling system (Endoron Medical Holdings Ltd., Dublin, Ireland) represents a novel approach to proximal endograft fixation, enabling simultaneous circumferential single-stage activation of 6 nitinol endostaples via balloon activation, providing a uniform and reproducible fixation pattern intended to mimic the longitudinal and radial anchoring of a surgical anastomosis. To support clinical implementation, this study systematically evaluated endograft displacement force across a range of activated staple configurations, including suboptimal deployment scenarios. The findings provide physicians with a mechanistic reference framework for preoperative planning, supporting procedural decision-making in anatomically challenging cases.