Gastroesophageal reflux after combined lower esophageal sphincter and diaphragmatic crural sling inactivation in the rat

This study tests the hypothesis that either selective or combined destructi on of the lower esophageal sphincter and the diaphragmatic crural sling sho uld induce reflux in the rat. Pull-through perfusion manometry was performe d before and after lower esophageal myectomy, crural myotomy, or both. pH m onitoring was used to detect reflux. Unmanipulated rats served as controls. Paired t tests were used for comparison of pre- and postoperative pressure values and contingency tables with Fisher's tests for examining the associ ation between the interventions and the appearance of reflux. Esophageal my ectomy decreased only sphincteric pressure from 25.9 +/- 15.5 to 9 +/- 6 mm Hg (P < 0.01), whereas crural myotomy decreased only sling pressure from 2 6.2 +/- 13.3 to 7.3 +/- 3.9 mm Hg (P < 0.01). Simultaneous performance of b oth procedures decreased sphincteric and crural pressures from 20.4 +/- 7.5 to 7.6 +/- 4.3 mm Hg (P < 0.01) and from 45.9 +/- 20.6 to 18.2 +/- 7.4 mm Hg (P < 0.01), respectively. None of the control, myectomy, or myotomy anim als showed reflux upon pH-metry but 5/8 rats in which both procedures were performed had prolonged acid exposure. No esophagitis was seen. In conclusi on, normal rats do not have reflux. Selective destruction of either the sph incter or the crural sling does not induce reflux, despite causing flatteni ng of their respective manometric profiles. Conversely, combined inactivati on of both components is significantly associated with reflux.