Hiatal Hernia 

A hiatal hernia occurs when a portion of the stomach prolapses through the diaphragmatic esophageal hiatus. Although the existence of hiatal hernia has been described in earlier medical literature, it has come under scrutiny only in the last century or so because of its association with gastroesophageal reflux disease (GERD) and its complications. There is also an association between obesity and the presence of hiatal hernia. By far, most hiatal hernias are asymptomatic and are discovered incidentally. On rare occasion, a life-threatening complication, such as gastric volvulus or strangulation, may present acutely.

The esophagus passes through the diaphragmatic hiatus in the crural part of the diaphragm to reach the stomach. The diaphragmatic hiatus itself is approximately 2 cm in length and chiefly consists of musculotendinous slips of the right and left diaphragmatic crura arising from either side of the spine and passing around the esophagus before inserting into the central tendon of the diaphragm. The size of the hiatus is not fixed, but narrows whenever intra-abdominal pressure rises, such as when lifting weights or coughing.^[1]

The lower esophageal sphincter (LES) is an area of smooth muscle approximately 2.5-4.5 cm in length. The upper part of the sphincter normally lies within the diaphragmatic hiatus, while the lower section normally is intra-abdominal. At this level, the visceral peritoneum and the phrenoesophageal ligament cover the esophagus. The phrenoesophageal ligament is a fibrous layer of connective tissue arising from the crura, and it maintains the LES within the abdominal cavity. The A-ring is an indentation sometimes seen on barium studies, and it marks the upper part of the LES. Just below this is a slightly dilated part of the esophagus, forming the vestibule. A second ring, the B-ring, may be seen just distal to the vestibule, and it approximates the Z-line or squamocolumnar junction. The presence of a B-ring confirms the diagnosis of a hiatal hernia. Occasionally, the B-ring also is called the Schatzki ring.

Any sudden increase in intra-abdominal pressure also acts on the portion of the LES below the diaphragm to increase the sphincter pressure. An acute angle, the angle of His, is formed between the cardia of the stomach and the distal esophagus and functions as a flap at the gastroesophageal junction and helps prevent reflux of gastric contents into the esophagus (see the image below).

The gastroesophageal junction acts as a barrier to prevent reflux of contents from the stomach into the esophagus by a combination of mechanisms forming the antireflux barrier. The components of this barrier include the diaphragmatic crura, the LES baseline pressure and intra-abdominal segment, and the angle of His. The presence of a hiatal hernia compromises this reflux barrier not only in terms of reduced LES pressure but also reduced esophageal acid clearance. Patients with hiatal hernias also have longer transient LES relaxation episodes particularly at night time. These factors increase the esophageal mucosa acid contact time predisposing to esophagitis and related complications.

Frequency

United States

Hiatal hernias are more common in Western countries. The frequency of hiatus hernia increases with age, from 10% in patients younger than 40 years to 70% in patients older than 70 years.

International

Burkitt et al suggest that the Western, fiber-depleted diet leads to a state of chronic constipation and straining during bowel movement, which could explain the higher incidence of this condition in Western countries.^[2]

Mortality/Morbidity

Paraesophageal hernias generally tend to enlarge with time, and sometimes the entire stomach is found within the chest. The risk of these hernias becoming incarcerated, leading to strangulation or perforation, is approximately 5%. This complication is potentially lethal, and surgical intervention is necessary. Because of the high mortality associated with this condition, elective repair often is advised wherever a paraesophageal hernia is found.^{[3, 4]}

Sihvo et al examined the mortality associated with adult paraesophageal hernia in a Finnish retrospective, population-based study.^[3] Five hundred sixty-three patients received surgical intervention and 67 received conservative treatment for paraesophageal hernia. Death occurred in 32 patients, of whom 29 had concomitant diseases.

Of the 563 patients in the surgical group, the overall mortality was 2.7% (15 patients), of whom 3 died following elective repair.^[3] Of the 67 patients in the conservative treatment group, 16.4% (11 patients) died; 13% (4 patients) of the deaths might have been avoided with elective surgical intervention. Of the 32 patients who died, over half had type III (16 patients; 50%) or type IV (9 patients; 28.1%) had hiatal hernias; 4 patients (12.5%) had had type II hiatal hernias, with the remaining 3 deceased having an unknown type. The causes of death were primarily from incarceration (24 patients; 75%), followed by surgical complications (6 patients; 18.8%) and bleeding ulcer (2 patients; 6.2%).^[3]

Sihvo et al recommended of the paraesophageal hernia, at least in symptomatic patients, except for those at high surgical risk.^[3]

In a Swiss study, Larusson et al investigated the predictive factors for postoperative morbidity and mortality in patients undergoing laparoscopic hernia repair.^[4] Of 354 laparoscopic paraesophageal hernia repairs, age at 70 years or older was significantly associated with postoperative morbidity (24.4%) and mortality (2.4%) relative to those younger than 70 years (10.1% postoperative morbidity, P = 0.001; 0% mortality, P = 0.045). Similar age findings were noted with gastropexy but not with fundoplication.^[4] In addition, high-risk patients had significantly higher morbidity but not mortality.

Larusson et al concluded that age, American Society of Anesthesiologists (ASA) score, and type of operation are significant predictive factors in patients undergoing laparoscopic paraesophageal hernia repair.^[4] The investigators advised caution in balancing surgical indications with each patient's comorbidities, age, symptoms, and potentially life-threatening complications. ^[4]

Sex

Hiatal hernias are more common in women than in men. This might relate to the intra-abdominal forces exerted in pregnancy.

Age

Muscle weakening and loss of elasticity as people age is thought to predispose to hiatus hernia, based on the increasing prevalence in older people. With decreasing tissue elasticity, the gastric cardia may not return to its normal position below the diaphragmatic hiatus following a normal swallow. Loss of muscle tone around the diaphragmatic opening also may make it more patulous.