Over-the-Scope-Clips Can Be Fired Safely Over a Guidewire: Proof of Concept in an Ex-Vivo Porcine Model.

Background and Objectives: To assist in achieving optimal position when deploying over-the-scope (OTS)-clips, the concept of cannulating the defect with a guidewire, backloading the endoscope onto the wire, and firing the OTS-clip over the wire with subsequent wire removal has been demonstrated. The safety of this technique has not been evaluated. Methods: An ex-vivo porcine foregut model was utilized. Biopsy punches were used to create 3-mm diameter full-thickness gastrointestinal tract defects through which a guidewire was threaded. An endoscope was backloaded over the wire and OTS-clips (OVESCO, Tuebingen, Germany) were fired over the mucosal defect and wire. The wire was removed through the endoscope and the removal difficulty was graded using a Likert scale. This process was repeated for each unique combination of nine OTS-clip types, two wire types, four wire angles, and three tissue types. Statistical analysis included t test and ANOVA. Results: Two hundred sixteen OTS-clip firings with wire removal attempts were performed with the following Likert score breakdown: 1 - No difficulty (80.6%), 2 - mild difficulty (16.2%), 3 - moderate difficulty (2.3%), 4 - extreme difficulty (0.9%), and 5 - unable to remove (0%). Statistically significant differences were noted in removal difficulty between OTS-clip sizes (p < 0.05). No differences were identified between clip teeth types, wire types, tissue types, and wire angles (p > 0.05). Conclusion: In this ex-vivo model, the guidewire was successfully removed through the endoscope in all cases. This technique can be employed to facilitate OTS-clip closure of gastrointestinal tract defects, but further study is indicated before wide clinical implementation.