Transesophageal mediastinoscopy by submucosal endoscopy with mucosal flap safety valve technique

Background: Indications for NOTES (natural orifice transluminal endoscopic surgery) studied so far are limited to intra-abdominal surgery. Objectives: To determine the technical feasibility and the safety of transesophageal mediastinocosopy by using the submucosal endoscopy with mucosal flap safety valve (SEMF) technique. Design: Two-week survival study with 4 porcine models. Interventions: High-pressure carbon dioxide injection and balloon dissection created a large submucosal working space for insertion of a cap-fitted endoscope. The muscularis propria was resected inside the submucosal space, and the mediastinoscopy was performed by using the endoscope inserted via the myotomy site. The muscular defect was sealed with the overlying mucosal flap, and the mucosal entry site was closed with clips. Main Outcome Measurements: Repeated endoscopy and necropsy were performed 2 weeks after the procedure. Results: With the SEMF technique, the posterior mediastinum was successfully accessed in all animals. Three pigs survived 2 weeks without clinical complications, and the defects were completely sealed by the mucosal flap. One pig with proximal esophageal mediastinal entry managed under voluntary respiration was euthanized because of pleural injury. Conclusions: The SEMF technique provided safe entry into the mediastinum, with a protective submucosal tunnel that prevented mediastinal soiling. Mid to distal esophageal access is safer than the higher level access. Mechanical ventilation might allow safer respiratory support.