Contribution of the His angle to the gastroesophageal antireflux mechanism

Abstract

The high pressure zone (HPZ) is a result of a series of combative forces that converge in the gastroesophageal junction and contribute to generate the pressure barrier. Recognized factors in this function are the positive intra-abdominal pressure transmitted to the lower esophagus, thoracic suction, the diaphragmatic hiatus, the intrinsic lower esophageal sphincter, and the effect of gastric fundus acting on the distal esophagus through the His angle. The exclusive and quantitative role of the His angle is evaluated with the help of two experimental models (in vivo and in vitro) in the dog. By manometric procedures the gastric pressure at which the sphincter opens (OP) is studied under overloaded conditions, both in the living animal and in a gastroesophageal specimen, varying the His angle from 90° to 0°. In the “in vivo” model the pressure of the barrier with a His angle of 90° was 7.33 ± 3.4 mm Hg and the OP of 8.66 +- 4.1 mm Hg, while with the His angle at 0° the pressure of this barrier was 10.66 +- 2.9 mm Hg and the OP 16 +- 6.9 mm Hg (p < 0.05). In the “in vitro” model the His angle at 0° multiplied the OP two or three times. We conclude that the His angle at 0° allows transmission of the fundic pressure extrinsically to the sphincter, giving way to a higher OP, and increasing the degree of competence.