Sliding and Paraesophageal Hernia
An acquired hiatal hernia is defined by the proximal movement of a portion of the stomach into the chest through the diaphragmatic hiatus. Within that general definition there are two subsets: a sliding hernia and a paraesophageal hernia. A sliding hiatal hernia occurs as a result of a direct proximal movement of the stomach through the hiatus with the gastroesophageal junction. It is thought to form as a result of laxity of the phrenoesophageal ligament that normally closes the diaphragmatic space around the gastroesophageal junction and anchors the junction in place. It is the most common type of hiatal hernia and is most associated with gastroesophageal reflux. The reason for this is multifactorial and includes (1) loss of the crural diaphragm contribution to lower esophageal sphincter tone, (2) stasis of refluxed content within the hernial sac, and (3) disruption of the acute angle of His, which has a valvelike function in preventing reflux. With larger crural defects and, hence, diameters of the hernia, these defects are more pronounced and the degree of reflux is greater. As a result, larger hiatal hernias tend to be more associated with complications of gastroesophageal reflux, such as erosive esophagitis, esophageal strictures, and Barrett esophagus. It is also more difficult to control the reflux through lifestyle and pharmacologic interventions; surgical correction such as fundoplication is needed in some patients.
In contrast, in a paraesophageal hernia, the gastroesophageal junction remains fixed in place without proximal migration of the proximal portion of the stomach. Although the herniation is through the phrenoesophageal membrane and hiatal opening, the junction stays in place through its attachment to the periaortic fascia and median arcuate ligament. The herniation may begin with the gastric fundus but in time progresses to include a large portion of the stomach, if not the entire stomach. When a large portion is involved, the stomach may flip up through the hiatus by two configurations. The first is in a mesenteroaxial direction, that is, on a dividing line between the proximal and distal stomach. When the entire stomach herniates through the diaphragm into an upsidedown position at both the proximal and distal margins of the stomach, this is termed an organoaxial hernia. A paraesophageal hernia is not deleterious necessarily because of gastroesophageal reflux but because of the threat of incarceration and strangulation of the stomach in the diaphragmatic hiatus due to vascular compromise of the angulated gastric vasculature. Patients may present at first with symptoms of postprandial chest or epigastric pain from partial obstruction and early satiety due to reduction of the size of the gastric pouch. Presentation with incarceration can be catastrophic excruciating chest pain and shock associated with frank gastric infarction and death if not addressed immediately. Surgical correction securing the stomach below the diaphragm and closing of the hiatus is needed for symptomatic patients or a young patient with a large hernia.
With large diaphragmatic defects, organs adjacent to the stomach such as the colon and spleen may also herniate into the chest. Finally, although these types of hiatal hernias are strictly defined, a combination of both a sliding and a paraesophageal hernia is common. These patients may present with both reflux symptoms and symptoms of pouch obstruction. As a result, surgical correction for these patients (if not for most patients with a large hernia of any type) requires both reduction of the hernia and fundoplication.