NISSEN FUNDOPLICATION PREVENTS SHORTENING OF THE SPHINCTER DURING GASTRIC DISTENSION

Objective: To determine the dynamic effects of a Nissen fundoplication on a volume-stressed lower esophageal sphincter(LES). Design: Before and after experimental study in 10 baboons. Setting: University animal research unit. Interventions: Continuous manometric evaluation of the esophagus cardia, and stomach during distention of the stomach with w ater. Slow motorized pull-through of the LES after each successive int ragastric increment of SO mt of water. Tests were performed again afte r a;Nissen fundoplication. Main Outcome Measures: Lower esophageal sph incter length and frequency of common cavity episodes after each volum e increment. The pressure and intragastric volume at the yield point a re defined as the point of permanent loss of the gastroesophageal pres sure gradient. Results: Gastric distention of the stomach with water r esulted in a progressive decrease in LES length and competency. The me dian+/-interquartile range LES length decreased by 1.5+/-0.3 mm for ev ery 1-mm Hg increase in gastric pressure-before fundoplication and by 0.2+/-0.1 mm after fundoplication (P<.02). With gastric distention the re was an indirect correlation between the degree of LES length and th e frequency of reflux episodes (r=-O.70). This correlation was abolish ed by a Nissen fundoplication (r=-0.31). The median+/-interquartile ra nge frequency of common cavity episodes (2.19+/-2.05 episodes per minu te) before fundoplication decreased significantly (P<.001) to 0+/-0.59 episodes per minute after fundoplication. The median+/-interquartile range yield pressure (13+/-9 mm Hg) and yield volume (825+/-855 mL) we re significantly (P<.01) improved after Nissen fundoplication to 39+/- 36 mm Hg and 1250+/-750 mL, respectively.Conclusion: By preventing sph incter shortening, a Nissen fundoplication improves competency of the LES to progressive degrees of gastric distention.