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. 1999 Jun;44(6):782–788. doi: 10.1136/gut.44.6.782

An ambulant porcine model of acid reflux used to evaluate endoscopic gastroplasty

S Kadirkamanathan 1, E Yazaki 1, D Evans 1, C Hepworth 1, F Gong 1, C Swain 1
PMCID: PMC1727549  PMID: 10323878

Abstract

BACKGROUND—There is a lack of suitable models for testing of therapeutic procedures for gastro-oesophageal reflux disease. Endoscopic sewing methods might allow the development of a new less invasive surgical approach to treatment of gastrointestinal disorders.
AIMS—To develop an animal model of gastro-oesophageal reflux for testing the efficacy of a new antireflux procedure, endoscopic gastroplasty, performed at flexible endoscopy without laparotomy or laparoscopy.
METHODS—At endoscopy a pH sensitive radiotelemetry capsule was sewn to the oesophageal wall, 5 cm above the lower oesophageal sphincter, in six large white pigs. Ambulant pH recordings (48-96 hours; total 447 hours) were obtained. The median distal oesophageal pH was 6.8 (range 6.4-7.3); pH was less than 4 for 9.3% of the time. After one week, endoscopic gastroplasty was performed by placing sutures below the gastro-oesophageal junction, forming a neo-oesophagus of 1-2 cm in length. Postoperative manometry and pH recordings (24-96 hours; total 344 hours) were carried out.
RESULTS—Following gastroplasty, the median sphincter pressure increased significantly from 3 to 6 mm Hg and in length from 3 to 3.75 cm. The median time pH was less than 4 decreased significantly from 9.3% to 0.2%.
CONCLUSIONS—These are the first long term measurements of oesophageal pH in ambulant pigs. The finding of spontaneous reflux suggested a model for studying treatments of reflux. Endoscopic gastroplasty increased sphincter pressure and length and decreased acid reflux.


Keywords: gastro-oesophageal reflux; endoscopic gastroplasty; manometry

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Figure 1  .

Figure 1  

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Endoscopic gastroplasty. Diagram indicates transverse and longitudinal section through the oesophagus and stomach to indicate the placement of stitches and site of implantation of radiotelemetry capsule. Two stitches are placed immediately below the cardio-oesophageal junction; the tissue is pulled together and tied with four half hitches. A separate pair of stitches is placed 1 cm below the first. There are several possible mechanisms by which endoscopic gastroplasty might improve reflux: it creates a neo-oesophagus out of gastric tissue, thus increasing the exposure of the lower oesophageal sphincter (LOS) to positive intra-abdominal pressure; it may increase lower oesophageal sphincter pressure by placing a tuck in the muscle layer at the lower end of the sphincter; it may make the angle of this more acute; by decreasing the potential for relaxation of the gastric sling fibres distension induced lower oesophageal sphincter relaxation may be reduced.

Figure 2  .

Figure 2  

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Preoperative and postoperative distal oesophageal acid exposure. Endoscopic gastroplasty significantly decreased acid reflux (p<0.05). The top trace shows preoperative 48 hour pH profile and the bottom trace shows postoperative 48 hour pH profile of the distal oesophagus.

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