Endoscopic "no hole" full-thickness biopsy of the stomach to detect myenteric ganglia.

BACKGROUND: The etiology of several common gastric motility diseases remains largely unknown. Gastric wall biopsy specimens that include the muscularis propria to evaluate the enteric nervous system, interstitial cells of Cajal, and related cells are essential to promote our understanding of the pathophysiologic mechanisms. On the basis of our previous work, a double EMR technique provided sufficient tissue to identify myenteric ganglia. A serious limitation to the technique was the resultant gastric wall perforation after tissue resection. The optimal procedure would seal the gastric wall defect before tissue resection, eliminating the risk of peritonitis. OBJECTIVES: The aims of this study were to (1) determine the technical feasibility and reproducibility of a full-thickness gastric biopsy by use of a novel double EMR technique without creating a perforation ("no hole") and to (2) determine safety of the procedure. DESIGN AND INTERVENTIONS: Preclinical study of 6 pigs. Each animal underwent a "no hole" double EMR survival procedure. To prevent perforation, detachable endoloops and prototype T-tag tissue anchors were placed before resection. At 2 weeks repeat endoscopy was performed followed by necropsy. MAIN OUTCOME MEASUREMENTS: Hematoxylin-eosin staining was used to determine which muscle layers were included in the resected specimen, and an antibody to neuronal nitric oxide synthase was used to visualize myenteric ganglia in the sample. Technical feasibility, reproducibility, and safety of the procedure were evaluated. RESULTS: Full-thickness gastric biopsy specimens were obtained from all animals without overt perforation. There were no procedural complications. Histologic examination showed muscularis propria with all layers of muscle present, and immunochemical studies demonstrated myenteric ganglia in all tissue samples. Four animals had an uneventful clinical course, and repeat endoscopy at week 2 showed ulceration with stellate fibrosis. Necropsy showed mild localized adhesions. Two animals were killed at days 3 and 6, respectively, because of suspected peritonitis. At necropsy, delayed perforations at the resection sites were noted with displaced endoloops and tissue anchors. CONCLUSION: This study explored the concept of obtaining deep muscle wall biopsy specimens with use of a unique approach of resection without perforation. The novel "no hole" double EMR technique was technically feasible and reproducible with sufficient tissue obtained to identify myenteric ganglia. However, there was a high delayed perforation rate associated with displaced endoloops and tissue anchors. On the basis of this early experience, improved safety data may be anticipated with future studies using improved tissue closure devices.

Chemically assisted endoscopic mechanical submucosal dissection by using mesna.

BACKGROUND: A class of thiol compounds, mesna (sodium-2-mercaptoethanesulfonate), has been used to facilitate tissue dissection in surgical fields. OBJECTIVES: To evaluate the technical feasibility and efficacy of chemically assisted endoscopic mechanical submucosal dissection (CAEMSD) by using mesna. DESIGN: An in vivo controlled blind trial by using porcine models. SETTINGS: Nonsurvival study in an animal laboratory. INTERVENTIONS: Six pigs were studied. Mucosal targets of about 2 cm (estimated) for treatment were created with a circle of cauterized spots along the greater curvature of the gastric body and the antrum. A mesna solution or the control hydroxypropyl methylcellulose solution was submucosally injected. The target mucosa was mechanically isolated with balloon dissection and removed by circumferential incision with a hook-knife inserted into the submucosal space. Necropsy and mucosal specimens from both groups were examined by histology. RESULTS: En bloc resection of the target was achieved in all 8 attempts of the mesna group and in 7 of 8 attempts of the control group. Use of mesna significantly reduced tissue resistance to the initial balloon-catheter insertion into the submucosa and the technical difficulty of subsequent submucosal balloon dissection by using a subjective grading system (P < .05). There was no difference in histology between both groups. CONCLUSIONS: CAEMSD is a unique methodology to facilitate mucosal resection.

Pilot study of transesophageal endoscopic epicardial coagulation by submucosal endoscopy with the mucosal flap safety valve technique (with videos).

BACKGROUND: We previously demonstrated that the thoracic cavity could be safely accessed by submucosal endoscopy with the mucosal flap safety valve (SEMF) technique. OBJECTIVES: To evaluate the technical feasibility of transesophageal access to the heart and epicardial ablation. DESIGN: One-week survival study with 5 porcine models. SETTINGS: Animal laboratory with general anesthesia. INTERVENTIONS: High-pressure carbon dioxide injection and balloon dissection created a large submucosal working space for insertion of a cap-fitted endoscope. A myotomy was performed inside the submucosal space. The thoracic cavity was endoscopically accessed through the myotomy site. A pericardial window was created with a needle-knife. A spot coagulation of the epicardium was performed with a heat probe and a hook-knife. The myotomy site was sealed with the overlying mucosal flap, and the mucosal entry site was closed with clips. MAIN OUTCOME MEASUREMENTS: An endoscopy and a necropsy were performed to study the esophagus, mediastinum, pericardial space, and cautery locations on the epicardium one week after the procedure. RESULTS: Epicardial coagulation was successfully performed within 30 minutes in 4 of the 5 pigs. Follow-up endoscopy demonstrated completely sealed myotomy sites by the overlying mucosal flap. There was no gross contamination or signs of contamination in the thoracic cavity. The pericardial space was normal in appearance. The epicardial coagulation sites were healing, without exudative ulceration. CONCLUSIONS: The SEMF technique allowed endoscopic access to the upper mediastinum, the pericardium, and the epicardium via the esophagus, along with a minimal intervention on the epicardium.

Evaluation of endoscopic approaches for deep gastric-muscle-wall biopsies: what works?

BACKGROUND: A major barrier to furthering our understanding of the pathophysiology of neuromuscular GI diseases, including functional GI disorders, is the inability to obtain deep gastric-wall biopsy specimens that include both layers of the muscularis propria, which allows evaluation of specific cell types, including myenteric ganglia. OBJECTIVES: The aims of this preclinical study were to (1) evaluate different endoscopic approaches for obtaining deep gastric-muscle-wall biopsy specimens and (2) determine if myenteric ganglia were present in the tissue samples. DESIGN AND INTERVENTIONS: This was a preclinical acute study by using a pig model. Multiple samples were obtained from 4 pigs. The endoscopic techniques evaluated were (1) EUS-guided tru-cut biopsy of the gastric wall, (2) jumbo biopsy of the post-EMR site, (3) jumbo biopsy of the gastrotomy margin, (4) serosal-side biopsy through a gastrotomy, and (5) double-EMR resection. MAIN OUTCOME MEASUREMENTS: Resected tissue was submitted for histology to determine which wall layers were included in the resected specimen. Hematoxylin and eosin staining was used to determine which muscle layers were biopsied, and an antibody to protein gene product 9.5 was used to determine if myenteric ganglia were present in the sample. RESULTS: Seventy-two tissue samples were obtained: EUS-guided tru-cut biopsy (n=16), jumbo biopsy of the post-EMR site (n=16), jumbo biopsy of the gastrotomy (n=16), serosal-side biopsy (n=16), and double-EMR resection (n=8). Only the double-EMR resection tissues showed the presence of longitudinal muscle, indicating the presence of both muscle layers and the myenteric plexus. Immunofluorescence studies demonstrated the presence of myenteric ganglia only in the double-EMR tissues and in none of the other gastric samples. No adjacent organs were included in the resection. CONCLUSIONS: The double-EMR technique was the only studied technique that resulted in a deep gastric-wall sample and provided sufficient tissue to evaluate both muscle layers and the intermuscular layer that contain myenteric ganglia. Further studies are needed to verify the efficacy and to assess the safety of this approach.

Endoscopic full-thickness closure of large gastric perforations by use of tissue anchors.

BACKGROUND: A flexible needle-catheter tissue-anchoring device was developed to accomplish full-thickness tissue apposition of the GI wall. The aim of this study was to identify the performance of this device for repair of large iatrogenic gastric perforations in a porcine model. OBJECTIVES: Six pigs. DESIGN: Short-term survival animal study. SETTINGS: Pigs were studied while they were under general anesthesia. Device performance in differing gastric locations and wall thicknesses was assessed by 2 perforations more than 2 cm in size created for each pig along the greater curvature and the anterior wall. INTERVENTIONS: Each perforation was closed by parallel placement of tissue anchor sets sequentially along the length of the perforation. MAIN OUTCOME MEASUREMENTS: One week follow-up endoscopy and necropsy were performed. RESULTS: Twelve perforations were closed with the 48 tissue anchor sets. All animals survived for 1 week without clinical complications. Follow-up endoscopy and necropsy revealed that all tissue anchors remained with firmly held sutures and sealed perforations. CONCLUSIONS: Full-thickness closure with a new tissue-anchoring device simply and successfully repaired large iatrogenic gastric perforations.

Submucosal endoscopy with mucosal flap safety valve.

BACKGROUND: There is no reliable endoscopic method to selectively resect deeper layers of the gut wall or to access the peritoneal cavity and prevent peritoneal soiling. OBJECTIVES: To determine the technical feasibility and safety of submucosal endoscopy with mucosal flap (SEMF) in accessing the peritoneal cavity through a large full-thickness gastric-muscle-wall resection. DESIGN: Ex vivo feasibility exploration and survival animal study. SETTINGS: Ex vivo samples were obtained from fresh harvested organs. In vivo procedures were conducted with the pigs under standard general anesthesia. INTERVENTIONS: High-pressure carbon dioxide (CO(2)) injection and balloon dissection created a large submucosal working space for insertion of a cap-fitted endoscope. By using the EMR cap, a full-thickness resection of the muscularis propria was performed. This full-thickness defect was sealed with the overlying mucosal flap and the use of hemoclips or tissue anchors. RESULTS: By using the SEMF technique in the ex vivo experiment, the gastric wall was successfully traversed in each stomach after submucosal dissection and full-thickness resection of the musclaris. Similarly, by using the SEMF technique in the in vivo procedures, the peritoneal cavity was successfully accessed and the defect was completely sealed by using the mucosal flap. All animals survived 1 week after the procedure. Ulceration was noted in 3 pigs, and a small bowel injury was noted in 1 pig. Leak testing was negative in all stomachs. CONCLUSIONS: By using the SEMF technique, submucosal space endoscopy and deep-layer gastric-wall resection were successfully performed. Furthermore, the mucosa overlying the dissected submucosal space served as a safe flap valve, preventing peritoneal leakage.

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.

Transgastric cholecystectomy: transgastric accessibility to the gallbladder improved with the SEMF method and a novel multibending therapeutic endoscope.

BACKGROUND: Transgastric cholecystectomy is thought to technically and anatomically challenge a single entry flexible endoscopic approach. OBJECTIVES: To examine the feasibility of a transgastric-only cholecystectomy, endoscope performance in an upper-abdominal operation, and the usefulness of an offset gastrotomy. STUDY DESIGN: Animal survival study. SETTING: Animal research laboratory. PATIENTS: Six domestic pigs. MAIN OUTCOME MEASUREMENTS: Transgastric access to the gallbladder and technical feasibility of unassisted transgastric cholecystectomy. INTERVENTIONS: A cephalad submucosal tunnel was created in the anterior gastric wall with a high-pressure CO2 injection. An EMR-cap myotomy was performed distally within the submucosal space and created an offset gastrotomy. An endoscope was inserted into the peritoneal cavity through the myotomy. Access to the gallbladder was compared by using a multibending therapeutic endoscope (R-scope), with a standard double-channel endoscope. A cholecystectomy was performed by using both types of endoscopes. The myotomy site was sealed with the overlying mucosal flap. The mucosal entry point was closed with clips or tissue anchors. RESULTS: A standard double-channel endoscope could access the gallbladder in 2 of 4 attempts. A multibending endoscope accessed the gallbladder in all 4 attempts, including 2 pigs in which the standard scope failed to access the gallbladder. In 4 pigs, a cholecystectomy was completed. Two pigs died during surgery, with air embolization observed in 1. Two pigs survived a planned 1-week survival period. CONCLUSIONS: Transgastric cholecystectomy is technically feasible. Transgastric access to the gallbladder may be improved by using submucosal endoscopy with an offset exit gastrotomy by means of the mucosal flap safety-valve technique and a multibending gastroscope.

Pilot study of the porcine uterine horn as an in vivo appendicitis model for development of endoscopic transgastric appendectomy.

BACKGROUND: Iatrogenic inflammation of the porcine uterine horn may serve as an in vivo appendicitis model for the development of endoscopic transgastric appendectomy. OBJECTIVE: Five female pigs. STUDY DESIGN: Animal study. SETTINGS: General anesthesia. MAIN OUTCOME MEASUREMENTS: Anatomical appearance and technical feasibility. INTERVENTIONS: Three pigs were used to identify an injectable material that would inflame the uterine horn, and 2 pigs were used for a pilot appendectomy. Three types of materials were individually injected into the bilateral uterine horns, and the ideal material to inflame the uterine horn was injected into the right uterine horn for the last 2 pigs. After 24 hours, the injected uterine horns of the first 3 pigs were assessed and a pilot appendectomy was performed in the last 2 pigs. RESULTS: Ethanolamine oleate (EO) injected uterine horns demonstrated similarities to the inflamed human appendix. Simulations of the appendectomy were successfully performed by using the EO model. LIMITATIONS: Suboptimal existing tools. CONCLUSIONS: This preliminary study demonstrated the technical feasibility to create a model for acute appendicitis by using the porcine uterine horn and transgastric appendectomy.