Antireflux mechanism in Nissen fundoplication--an experimental study.

The antireflux mechanism of the Nissen fundoplication was investigated in 15 mongrel dogs by esophageal manometry. Nissen fundoplication increased the lower esophageal resting pressure for 2 weeks after operation; however, by 4 weeks it had decreased to a level which did not differ significantly from the preoperative value. Thus, lower esophageal sphincter (LES) length, unlike LES pressure, was maintained for a long period. These results suggest that restoration of competence at the gastroesophageal junction after Nissen fundoplication depends on an adequate length of LES as well as increased LES pressure. The gastrin-stimulated LES pressure 1, 2 and 4 weeks after operation was significantly higher than the preoperative stimulation pressure. Therefore, it seems that the antireflux mechanism is associated not only with the mechanical aspect of the wrapping but also with creation of a new muscular sphincter substitute that reacts sufficiently to gastrin stimulation.