Endoscopic augmentation of the cardia with a biocompatible injectable polymer (Enteryx) in a porcine model

Background: Endoscopic approaches to restore the gastroesophageal barrier in patients with gastroesophageal reflux disease (GERD) are presently undergoing clinical trial. The aim of the study was to demonstrate the feasibility, durability, safety, and antireflux efficacy following augmentation of the cardia with a biocompatible injectable polymer (Enteryx). Methods: Augmentation was performed in 12 Yucatan mini-pigs. The cardia was injected circumferentially with 1-1.5 ml of Enteryx at three or four sites. Four groups of three animals each were killed at 2, 6, 12, and 24 weeks following augmentation. Gastrointestinal endoscopy and esophageal manometry were performed preoperatively and postoperatively. Competency was determined as the intragastric pressure (yield pressure) and volume (yield volume) needed during gastric distension with air and water to result in equalization of gastric and esophageal pressure. Comparisons were made with a group of noninjected animals (n = 6). Results: All animals had a normal eating pattern: none showed any, evidence of vomiting or regurgitation. The median injection volume was 4 ml (range. 1-8). At autopsy, implants were found in 83% of the animals. Intramuscular placement of the implant was durable, whereas sloughing occurred if the implant was placed submucosally. The mechanical properties of sphincter length and pressure were unaffected by the injection. The median yield pressure of the animals that survived for >6 weeks (21.4 mmHg) was significantly greater (p = 0.049) than the animals that survived for <6 weeks (4.5 mmHg) and greater (p = 0.054) than the control animals (9.1 mmHg), suggesting that the healing process was associated with reduced distensibility of the cardia. Conclusions: Augmentation of the cardia with an injectable polymer (Enteryx) is simple, safe, and durable. Early studies suggest that alteration in the distensibility and geometry of the gastroesophageal junction may provide antireflux protection.