Endoscopic knot tying: In vitro assessment in a porcine stomach model

Aim: To determine if surgical knotting performed via endoscopy is an effective closure method for natural orifice translumenal endoscopic surgery.

Methods: The proposed method was tested on an in vitro pig stomach model using standard endoscopy suite materials. A single use laparoscopy trocar (Versaport Plus manufactured by Tyco Healthcare) was fixed onto a plastic rectangular box in a horizontal position. A fresh pig stomach was tightly attached via its esophageal end to the trocar opening on the inner side of the box. The stomach cavity was closed at the duodenal end with Kocher forceps. A standard upper gastrointestinal endoscope fitted at its tip with a transparent plastic cap was introduced into the stomach through the outer trocar opening, so that the passage of the surgical trocar would mimic the passage of an esophagus. The stomach was subsequently inflated, followed by irrigation and washing. A neutral electrode of an electrocautery unit was placed inside the plastic box, underneath the pig stomach. The stomach's outer surface was kept moist using normal saline in order to maintain the natural elasticity and to ensure good contact with the electrode.

Results: The submucosal space on the anterior face of the stomach was accessed using the technique of endoscopic submucosal dissection. First, a site on the anterior face of the stomach was chosen, near the angle. Then, saline was injected into the submucosa with a standard endoscopic needle, so as to create a 20 mm diameter elevation. A linear 15 mm vertical incision was created at its center using a Dual Knife (KD650U manufactured by Olympus). This incision was used to access the submucosal space, and about 10 mm was dissected on both sides of the incision. The endoscope was then pushed through to the outside of the stomach after dilating a small puncture made by the Dual Knife in the muscularis propria, which simulated the peritoneoscopy procedure. Then, a 0.025" guidewire (Jagwire/450 cm manufactured by Boston Scientific) was inserted into the puncture, followed by a dilating balloon (Quantum TT manufactured by Cook Medical) that was used to enlarge the aperture orifice. After withdrawing the scope back into the stomach, the procedure continued with guidewires being passed from the submucosal space into the gastric lumen through small orifices on the left and right sides of the mucosal opening. These orifices were made with the Dual Knife, and the guidewires were inserted via a guiding catheter (HGC-6 manufactured by Cook Medical). As the guidewires were pulled outside of the stomach, they were replaced with a single surgical suture that had been initially attached to their tip and was now untied. Finally, one loop of this surgical suture was formed on the exterior. One loop end was fixed while the opposite suture end was pulled by biopsy forceps through the endoscope channel as the scope was inserted into the stomach. The loop was advanced until it approached and fixed the two mucosal incision margins. Three alternating loops were made in this manner to create a genuine tight surgical knot.

Conclusion: Endoscopic knotting of the gastric wall is feasible, but an in vitro survival study is necessary to validate clinical significance.