A porcine model of gastroesophageal reflux.

The exact mechanism by which the lower esophageal sphincter (LES) prevents gastroesophageal reflux disease (GERD) remains controversial. The two main reasons for this controversy are the lack of a good animal model and the only recent technologic advances in this field. To date, no animal models exist that use 24-hour pH studies, manometry, and endoscopy in evaluating GERD. The purpose of this study is to create a good model of GERD that uses this technology and to delineate the true nature of the LES more clearly. Recently, three-dimensional vector volume studies were performed and through detailed, cadaveric, anatomic studies, the vector volume profiles were correlated to distinct groups of muscle fibers at the gastroesophageal junction in humans. In this study, an anatomic analysis of the porcine gastroesophageal junction revealed an arrangement of muscle fibers similar to that in humans. A myectomy of the porcine oblique fibers was performed in nine piglets weighing 10 to 12 kg. The authors were able to demonstrate manometric attenuation of the porcine LES, gastroesophageal reflux by ambulatory 24-hour pH monitoring (P < 0.0025), and the creation of GERD by documenting esophagitis grossly and histologically. In conclusion, this model of GERD works and lends further support to the notion that the LES may be a discrete anatomic entity.