Antireflux surgery for symptomatic gastroesophageal reflux: mechanism of action.

To determine the effects of Nissen fundoplication upon the symptoms of reflux and the diagnostic tests employed to evaluate reflux and to examine the relationship between gastroesophageal reflux and lower esophageal sphincter pressure before and after fundoplication, 10 patients with symptomatic reflux were studied before and after operation. Clinical evaluation, barium esophagography, endoscopy with mucosal biopsy, esophageal manometry, acid-perfusion and acid-reflux testing, and gastroesophageal scintiscaning were performed on each patient before and after surgery. Following fundoplication, marked symptomatic, radiographic, endoscopic, and histologic improvement was observed. Serial acid-reflux tests at increasing gastroesophageal pressure gradients returned to normal after surgery. Lower-esophageal-sphincter (LES) pressure increased from 8.2 +/- 1.3 to 12.0 +/- 1.5 mm Hg (P less than 0.01). In addition, surgery resulted in a significant decrease in the gastroesophageal reflux index from 17.4 +/- 2.4 to 2.7 +/- 1.1% (P less than 0.001). Surprisingly, the pre- and postoperative resting LES pressures did not correlate significantly with corresponding gastroesophageal reflux indices for individual patients. We conclude that increased LES pressure alone does not explain adequately the functional and clinical improvement which follows fundoplication.