Endoscopic Implantation of PMMA At the Submucosa of the Esophagogastric Junction in Mini-Pigs: Durability, Accuracy and Antireflux Barrier Augmentation

Abstract

Background: deep endoscopic implantation of biocompatible polymer in the distal oesophagus has been used as treatment for gastro-oesophageal reflux disease but esophageal perforations with deaths have been reported. Furthermore, implant loss has been described in both animal and human studies. Aims: to assess implant durability, accuracy and antireflux barrier augmentation six months after endoscopic implantation of polymethylmethacrylate (PMMA) at the submucosa of the oesophagogastric junction (EGJ). Methods: eight Macau-Piau mini-pigs underwent gastric yield volume (GYV) and gastric yield pressure (GYP) measurements before and six months after endoscopic implantation of PMMA aiming the submucosa of the EGJ. After sacrifice, PMMA localization and tissue reaction were searched. Results: Four PMMA implants were performed in each animal in a single procedure and no complications were observed. After six months, at least three submucosal nodules of PMMA were identified in all animals and no extramural deposits were found at necropsy. Microscopic analysis of the EGJ localized PMMA in the following layers (median percentage and interquartile range): submucosa 54% (43-85.5%), muscularis propria 9.5% (8.5-38.5%), mucosa 8% (0-23.5%) and subserosa 0% (0-14.5%). Innate chronic inflammation and fibrous tissue deposit were uniformly seen surrounding PMMA microspheres. Augmentation of the antireflux barrier was achieved by a significant increase in GYV (1404 vs. 905 ml; p = 0.02) and GYP (8.1 vs. 6.5 mm Hg; p = 0.057). Conclusions: Endoscopic implantation of PMMA at the EGJ was durable in all animals, had high accuracy aiming the submucosal layer and augmented the antireflux barrier after six months.