gastrointestinal disorders
Gastroesophageal Reflux Disease (GERD)
Etiology of GERD
The presence of reflux implies lower esophageal sphincter (LES) incompetence, which may result from a generalized loss of intrinsic sphincter tone or from recurrent inappropriate transient relaxations (ie, unrelated to swallowing). Transient LES relaxations are triggered by gastric distention or subthreshold pharyngeal stimulation. Factors that contribute to the competence of the gastroesophageal junction include the angle of the cardioesophageal junction, the action of the diaphragm, and gravity (ie, an upright position) and the patient's age. Factors that may contribute to reflux include weight gain, fatty foods, caffeinated or carbonated beverages, alcohol, tobacco smoking, and drugs. Drugs that lower LES pressure include anticholinergics, antihistamines, tricyclic antidepressants, calcium channel blockers,progesterone, and nitrates. GERD may lead to esophagitis, esophageal ulcer, esophageal stricture, Barrett esophagus (replacement of normal squamous epithelium of the distal esophagus with metaplastic columnar epithelium during the healing phase of acute esophagitis), and Adenocarcinoma of the esophagus . Factors that contribute to the development of esophagitis include the caustic nature of the refluxate, the inability to clear the refluxate from the esophagus, the volume of gastric contents, and local mucosal protective functions. Some patients, particularly infants, may aspirate the reflux material; however, the cause of pulmonary aspiration is rarely GERD. This image shows grade B esophagitis. Image provided by Kristle Lynch, MD. Gastroesophageal reflux may cause esophagitis to manifest as distal esophageal erosions and ulcerations (arrows). Scarring may eventually lead to stricture. Image provided by Kristle Lynch, MD. This image shows esophageal stricture caused by longstanding reflux disease and also shows superficial ulcerations. Image provided by David M. Martin, MD. In this image of Barrett esophagus, red-appearing bands of metaplastic epithelium can be seen extending proximally. Image provided by Kristle Lynch, MD. 