Myocardial vagal stimulation impairs lower esophageal sphincter function.

Abstract

Coronary artery disease and gastroesophageal reflux disease frequently coexist, but a direct pathophysiologic link has not been established. This study examines the effect of myocardial vagal receptor stimulation on lower esophageal sphincter (LES) tone in eight adult mongrel dogs, each acting as its own control. Pharmacologic stimulation was carried out by the application of 1 cm gauze patches soaked in nicotine (200 micrograms/ml) to the epicardium. Epicardial vagal receptors were stimulated mechanically by digital friction. Pharmacologic stimulation produced a rapid fall in LES tone from a mean (SEM) of 12.6 (1.5) to 8.6 (0.9) sphinctometer units (p = 0.007). Mechanical stimulation also produced a rapid fall from 12.0 (1.5) sphinctometer units to 6.8 (0.7) (p = 0.007). Both were associated with a drop in mean arterial blood pressure and heart rate. Sham patches soaked in sterile water produced no effects. These data suggest a direct vagal reflex linking the myocardium and the LES that may explain the high incidence of gastroesophageal reflux in patients with heart disease.