The primary barrier to gastroesophageal reflux is provided by the lower esophageal sphincter (LES). This sphincter is unique in that it is a physiologic entity rather than an anatomic structure. The LES is located just above the esophagogastric junction and is identified as an area of high pressure on esophageal manometry. Additionally, an acute angulation between the esophagus and the gastric cardia, termed the angle of His , likely provides a barrier to reflux.

Several factors contribute to the high-pressure zone of the LES. The normal anatomic location of the LES is within the abdominal cavity. The positive pressure within the abdomen and the negative pressure within the thorax are transmitted to the LES. The crura of the diaphragm may partially compress the LES, and finally, the esophageal musculature supplies tone to the distal esophagus. Normally the distal esophageal musculature is contracted. Upon swallowing, the musculature relaxes to allow passage of liquid and solid into the stomach and then returns to its normal tonic state. Patients with GERD typically have a relatively flaccid LES with inopportune transient relaxations.

Most patients with GERD have a hiatal hernia. The most common hiatal hernia in GERD patients is a sliding hiatal hernia, in which the gastroesophageal junction migrates into the thorax while the fundus remains in the abdomen. The phrenoesophageal ligament, a continuation of the endoabdominal fascia, stretches to accommodate the cardia of the stomach as it migrates into the chest, thus becoming the hernia sac ( Fig. 34-1 ). The LES is exposed to negative thoracic pressure and the angle of His is disrupted. Hence the function of the LES is compromised, and reflux of gastric contents into the distal esophagus occurs.

The goal of any antireflux procedure is to re-create a barrier to reflux of gastric and duodenal contents into the lower esophagus. Some of the principles of laparoscopic antireflux surgery include reduction of the hiatal hernia and its hernia sac, extensive mediastinal dissection of the esophagus to create adequate intra-abdominal length, and mobilization of the fundus with creation of a short, floppy fundoplication. Because there is no dissection or mobilization during endoscopic antireflux procedures, the indications for endoluminal procedures for GERD are limited.

In general, only patients who have a small hiatal hernia (<3 cm) and an adequate resting LES pressure (>5 mm Hg) should be considered for endoscopic antireflux procedures. There should be no evidence of Barrett metaplasia, and the patient should be able to tolerate moderate sedation. Finally, the patient should be made aware of the limited available data supporting endoscopic treatment of GERD.

Some might argue that the best candidates for endoscopic antireflux procedures are those who need it least—those with small hiatal hernias whose symptoms respond well to antacid medication. At present the indications are limited and will likely remain so until additional evidence is accumulated supporting widespread application of endoluminal therapies.