Smooth muscle remodeling of the gastroesophageal junction after endoluminal gastroplication

Background Endoluminal gastroplication has been shown to reduce symptoms of gastroesophageal reflux disease and to induce focal hypertrophy of the gastroesophageal junction (GEJ) muscularis propria. Despite suture loss, some patients have persistent symptomatic resolution. Objective This study was designed to examine the durability of smooth muscle hypertrophy after suture removal. Design Seven pigs underwent upper endoscopy with endoscopic ultrasonography (EGD/EUS) at baseline to evaluate GEJ muscularis propria layer. Endoluminal gastroplication was performed at week 1 with placement of 2 sutures at the GEJ. Repeat EGD/EUS was performed at week 3 and week 5. Three of the 7 pigs were killed for histologic analysis. The remaining 4 pigs had sutures removed and survived for 9, 11, and 13 weeks; serial weekly EGD/EUS was performed until the animal was killed. Results The GEJ muscularis propria thickness by EUS was 1.1 ± 0.1 mm at baseline, 4.7 ± 1.9 mm at week 3, and 4.4 ± 1.1 mm at week 5. The muscularis propria thickness by histologic examination in the 3 animals with sutures intact were 6.2 ± 0.3 mm near the suture site and 4.7 ± 0.5 mm at the opposing wall to the suture site. For the 4 animals with sutures removed, the measurements were 6.9 ± 0.2 mm (suture site) and 4.7 ± 0.5 mm (opposing wall), respectively. Conclusions The GEJ smooth muscle cell hypertrophy induced by endoluminal gastroplication persisted after removal of mucosal sutures. These changes may be responsible for persistent symptomatic response despite suture loss in patients.