A novel gel provides durable submucosal cushion for endoscopic mucosal resection and endoscopic submucosal dissection.

BACKGROUND: Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have transformed the ability to endoscopically remove superficial lesions throughout the gastrointestinal tract. The purpose of this study was to determine the properties and safety of a novel gel designed for the purpose of submucosal injection for EMR and ESD. METHODS: Upper endoscopy was performed in six Yorkshire pigs with 5-8 submucosal injections of varying amounts of Cook Medical (Bloomington, IN) gel were delivered in the stomach of each animal. A submucosal bleb of 1-2 ml normal saline was created followed by subsequent injection of 1-5 ml of the gel. Four animals were immediately euthanized and necropsy was performed after gel delivery and in two pigs; repeat endoscopy was performed after 4 weeks followed by necropsy. RESULTS: Thirty-nine submucosal injections were performed in six pigs. Every injection resulted in adequate mucosal lifting with a shoulder and defined margin and no cases of gel extravasation. Twenty-seven injections were performed in four pigs followed by immediate necropsy. The submucosal cushion was still present at the time of organ extraction without evidence of perforation, bleeding or tissue damage. Unroofing of the mucosal layer demonstrated a clean submucosal tissue dissection without bleeding or tissue damage. Twelve submucosal injections were performed in two pigs, and repeat endoscopy at 4 weeks demonstrated persistent submucosal cushion without evidence of mucosal ischemia or ulceration. Necropsy demonstrated no evidence of perforation, bleeding, or gel extravasation. Unroofing the mucosa confirmed a clean submucosal dissection. The injectate did not result in mesenteric fibroinflammatory reaction, tissue damage, or adhesion formation after 4 weeks. CONCLUSIONS: The gel appears to be a safe injectate that provides a submucosal cushion with a duration that is longer than other available injectates for EMR and ESD. The clean submucosal dissection may decrease the length of these procedures while minimizing complications.

Stent placement provides safe esophageal closure in thoracic NOTES(TM) procedures.

BACKGROUND: Safe esophageal closure remains a challenge in transesophageal Natural Orifice Transluminal Endoscopic Surgery (NOTES). Previously described methods, such as suturing devices, clips, or submucosal tunneling, all have weaknesses. In this survival animal series, we demonstrate safe esophageal closure with a prototype retrievable, antimigration stent. METHODS: Nine Yorkshire swine underwent thoracic NOTES procedures. A double-channel gastroscope equipped with a mucosectomy device was used to create an esophageal mucosal defect. A 5-cm submucosal tunnel was created and the muscular esophageal wall was incised with a needle-knife. Mediastinoscopy and thoracoscopy were performed in all swine; lymphadenectomy was performed in seven swine. A prototype small intestinal submucosal (SurgiSIS(®)) covered stent was deployed over the mucosectomy site and tunnel. Three versions of the prototype stent were developed. Prenecropsy endoscopy confirmed stent location and permitted stent retrieval. Explanted esophagi were sent to pathology. RESULTS: Esophageal stenting was successful in all animals. Stent placement took 15.8 ± 4.8 minuted and no stent migration occurred. Prenecropsy endoscopy revealed proximal ingrowth of esophageal mucosa and erosion with Stent A. Mucosal inflammation and erosion was observed proximally with Stent B. No esophageal erosion or pressure damage from proximal radial forces was seen with Stent C. On necropsy, swine 5 had a 0.5-cm periesophageal abscess. Histology revealed a localized inflammatory lesion at the esophageal exit site in swine 1, 3, and 9. The mucosectomy site was partially healed in three swine and poorly healed in six. All swine thrived clinically, except for a brief period of mild lethargy in swine 9 who improved with short-term antibiotic therapy. The submucosal tunnels were completely healed and no esophageal bleeding or stricture formation was observed. All swine survived 13.8 ± 0.4 days and gained weight in the postoperative period. CONCLUSIONS: Esophageal stenting provides safe closure for NOTES thoracic procedures but may impede healing of the mucosectomy site.

Loop-anchor purse-string closure of gastrotomy in NOTES(R) procedures: survival studies in a porcine model.

INTRODUCTION: Transgastric NOTES(®) procedures remain without a simple method to close the gastrotomy. In four survival swine studies, we have tested a novel gastric closure device: the loop-anchor purse-string (LAPS) closure system. METHODS: In four anesthetized pigs, an endoscopic gastrotomy was performed. Four loop anchors were arrayed in a 2-cm square pattern around the gastrotomy. The endoscope was passed into the abdominal cavity, and the gastrotomy was cinched closed. RESULTS: Procedure times ranged from 50-180 minutes. Three pigs survived 14 days. One animal was sacrificed early due to signs of sepsis. Another animal developed fevers and was treated with antibiotics. At necropsy, there were no abscesses, including in the septic animal. Histologic examination revealed evidence of healing in all animals. DISCUSSION: The LAPS system holds promise with early success in an animal model. Future human studies are needed to determine viability as a human visceral closure device.

Infection during natural orifice transluminal endoscopic surgery: a randomized, controlled study in a live porcine model.

BACKGROUND: Currently reported natural orifice transluminal endoscopic surgery (NOTES) procedures in animals have been done in heterogeneous milieus ranging from nonsterile to sterile procedures, with mixed results, including no infection in those performed in nonsterile settings. OBJECTIVE: To establish the potential frequency of infection during NOTES, comparing sterile to nonsterile approaches. SETTING: Survival experiments on sixteen 50-kg pigs. DESIGN AND INTERVENTIONS: From pilot data (100% infection frequency after nonsterile procedures), sample size (8 animals in each group) was calculated by using a power of 95% and an alpha risk of 0.05. The animals were randomly assigned to two groups: In the transgastric peritoneoscopy study group, liver and ovarian biopsies were performed with sterile overtubes, endoscopes, and accessories and the use of preoperative intravenous antibiotics and antiseptic gastric lavage. In the nonsterile (control) group, the same procedures were performed with nonsterile endoscopes and accessories without the use of gastric lavage and preoperative antibiotics. Complete transmural closure of the transgastric access site was made in all animals. After a 1-week survival time, all animals were killed for necropsy, which included Gram staining and peritoneal cultures. MAIN OUTCOME MEASUREMENTS: Intraperitoneal infection on necropsy. RESULTS: All necropsies revealed intraperitoneal infection (abscesses, fibrinopurulent exudates, and adhesions) in the control group (frequency of infection 100%). Peritoneal bacterial culture grew various aerobic and anaerobic organisms. No gross or bacteriological evidence of infection was seen in the sterile group (frequency of infection 0%, P value = <.0002). LIMITATIONS: Animal experiments. CONCLUSION: Nonsterile conditions invariably lead to intraperitoneal infection. Aseptic techniques during NOTES can prevent intra-abdominal infection. Future studies will determine which infection prevention steps are mandatory and which can be omitted during NOTES procedures.

Loop-anchor purse-string versus endoscopic clips for gastric closure: a natural orifice transluminal endoscopic surgery comparison study using burst pressures.

BACKGROUND: The success of natural orifice surgery depends on a reliable, secure closure of the opening in the gut. Few tests of the integrity of these closures have been published. OBJECTIVE: To determine whether a gastrotomy can be closed safely and effectively from within the stomach by using looped T-anchors-a novel, endoscopically placed device. DESIGN: Head-to-head comparison trial of 2 closure methods in 9 explanted porcine stomachs. SETTING: Animal laboratory. INTERVENTION: Paired gastrotomies were made in porcine explants. One was closed by using endoscopic clips, and the other was closed by using modified T-anchors in a purse-string fashion. MAIN OUTCOME MEASUREMENTS: Gastric transmural pressure gradients at bursting of these closures were measured while the explanted stomachs were inflated with a high-pressure insufflator. RESULTS: The mean burst pressure of the looped T-anchors was 27.3 mm Hg, whereas that of the clip closures was 14 mm Hg. By using 10 mm Hg as a threshold for a "secure" closure, 7 of 9 clip closures failed to meet the threshold value, whereas all 9 of the T-anchor closures met or exceeded the threshold value (P = .0023, 2-tailed Fisher exact test). LIMITATION: Nonsurvival study. CONCLUSION: Looped T-anchors provide a secure gastric closure for natural orifice surgery and are superior to endoscopic clips for this purpose.

A new alternative for a transjugular intrahepatic portosystemic shunt: EUS-guided creation of an intrahepatic portosystemic shunt (with video).

BACKGROUND: Transjugular intrahepatic portosystemic shunt (TIPSS) is an effective treatment for portal hypertension and its associated complications. EUS-guided creation of an intrahepatic portosystemic shunt (IPSS) may become a useful alternative to conventional TIPSS. OBJECTIVE: To assess the feasibility of EUS-guided IPSS creation in a live porcine model. SETTING: Acute and survival experiments in 50-kg pigs. DESIGN AND INTERVENTIONS: Under linear-array EUS guidance, the hepatic vein (HV) and then the portal vein (PV) were punctured with a 19-gauge FNA needle. A 0.035-inch guidewire was advanced through the needle into the PV lumen. The needle was exchanged over the wire, a metal stent was deployed under EUS and fluoroscopic guidance, and the distal end of the stent was positioned inside the PV and the proximal end within the HV. Eight animals were euthanized after the procedure, and 2 animals were kept alive for 2 weeks. MAIN OUTCOME MEASUREMENTS: Successful EUS-guided IPSS creation. RESULTS: Portosystemic shunt placement was successful in all animals. Intrahepatic vascular puncture and stent deployment were technically easy. Portosystemic flow through the shunt was documented by portal venogram and EUS Doppler. Necropsy performed after acute and survival experiments revealed no evidence of bleeding or damage to any intraperitoneal organs. There were no complications during the follow-up period in the 2 animals that were kept alive. LIMITATION: Experiments were performed in healthy animals with normal PV pressure. CONCLUSION: EUS-guided IPSS creation is technically feasible and may become an alternative to the currently used method of TIPSS placement.

Air and fluid leak tests after NOTES procedures: a pilot study in a live porcine model (with videos).

BACKGROUND: Transluminal access site closure remains a major challenge in natural orifice transluminal endoscopic surgery (NOTES). OBJECTIVE: Our purpose was to develop in vivo leak tests for evaluation of the integrity of transgastric access closure. SETTINGS: Survival experiments on 12 50-kg pigs. DESIGN AND INTERVENTIONS: After a standardized transgastric approach to the peritoneal cavity and peritoneoscopy, the gastric wall incision was closed with T-bars (Wilson-Cook Medical, Winston-Salem, NC) deployed on both sides of the incision and then cinched together. Gastrotomy closure was assessed with air and fluid leak tests. The animals were observed for 1 week and then underwent endoscopic evaluation and necropsy. MAIN OUTCOME MEASUREMENTS: (1) Leak-proof closure of the gastric wall incision. (2) Gastric incision healing 1 week after the procedure. RESULTS: The mean intraperitoneal pressure increased 10.7 +/- 3.7 mm Hg during gastric insufflation when the air leak test was performed before closure compared with 0.9 +/- 0.8 mm Hg after transmural closure of the transgastric access site with T-bars (P < .001). Fluid leak tests demonstrated no leakage of liquid contrast from the stomach into the peritoneal cavity after closure. Necropsy in 1 week confirmed completeness of the gastric closure in all animals with full-thickness healing and no spillage of the gastric contents into the peritoneal cavity. LIMITATIONS: Leak tests were only evaluated on an animal model. CONCLUSIONS: Fluid and air leak tests are simple techniques to evaluate in vivo the adequacy of the transluminal access site closure after NOTES procedures. Leak-proof gastric closure resulted in adequate tissue approximation and full-thickness healing of the gastric wall incision.