The diaphragm has three hiatuses that allow important structures to pass from thorax to abdomen (or vice versa). From most superior to most inferior, these hiatuses are the caval foramen (T8), the esophageal hiatus (T10), and the aortic hiatus (T12). Of these three, the esophageal hiatus is most prone to allowing abdominal contents to herniate into the thorax. This is thought to be due to the pulling effect that swallowing has on the stomach, via the contracting esophagus. A hiatal hernia is a protrusion of stomach through the esophageal hiatus into the thorax.
There are two main types of hiatal hernia:
- Sliding hiatal hernia - The gastroesophageal junction moves up through the esophageal hiatus along with some of the stomach. Although in some patients with this condition the gastroesophageal junction can reside permanently in the thorax, most patients only have a temporary herniation when they swallow. In these patients, the esophageal hiatus has been weakened or the esophagus itself has become shortened, and so contraction of the esophagus upon swallowing pulls the gastroesophageal junction and a piece of stomach temporarily through the esophageal hiatus. After swallowing, the gastroesophageal junction and stomach return to their normal position in the abdomen. This type of hiatal hernia accounts for approximately 95% of hiatal hernias, and is less serious than the para-esophageal hiatal hernia.
- Para-esophageal hiatal hernia - In contrast to a sliding hiatal hernia, the para-esophageal hernia involves a gastroesophageal junction that stays where it belongs in the abdomen, but has a part of the stomach, usually the fundus, that passes through the hiatus into the thorax. These hernias remain in the chest at all times and are not returned to a normal position by swallowing. Para-esophageal hiatal hernias are typically more problematic due to the pressure they put on the esophagus and the constriction placed on the herniated piece of stomach by the diaphragm.
A is the normal anatomy. B is a pre-stage that is prone to herniation. C is a sliding hiatal hernia. D is a para-esophageal hiatal hernia.
Signs and Symptoms
In most cases a hiatal hernia causes no symptoms, and patients can happily live their lives never knowing they have one. Larger hernias and para-esophageal hernias are generally more symptomatic and more prone to developing serious complications. Some professionals call the hiatal hernia the "great mimic" because its symptoms resemble so many other conditions. For example, dull chest pains (from acid reflux), shortness of breath (from diaphragmatic or, in severe cases, lung obstruction), and heart palpitations (from vagus nerve irritation) can all be seen in a patient with a hiatal hernia. Typical symptoms are those generally associated with GERD (gastroesophageal reflux disease), as well as frequent vomiting if the hernia is severe. Para-esophageal hernias carry the added risk of ulcers and even necrosis of the herniated portion of stomach.
Hiatal Hernia on CT Scan
The movie file below is a CT scan of cadaver 33475. Look at time= 50, L10, this is the esophagus just beneath the trachea. Continue to scan down while following the esophagus (the black lumen is not visible throughout the esophagus. If you need help remaining oriented to the esophagus, look at time= 53, K11, this is the esophagus just posterior and slightly to the left of the tracheal bifurcation). What would be seen normally as you move down a CT scan is the esophagus remaining medial and anterior to the descending aorta, with the fundus of the stomach coming into view before you see the esophagus branching to the left into the stomach. In cadaver 33475, as we follow the esophagus down we see it emptying into a large structure in the thorax. This is presumably a large sliding hiatal hernia because we see the gastroesophageal hiatus well above the diaphragm. As we scan further down, the large herniated portion of stomach can be seen shifting over medially to squeeze through the esophageal hiatus, and then emptying again into the unherniated portion of the stomach (time= 60, L13).
Because sliding hiatal hernias are often uncomplicated and cause only those symptoms found in GERD, treatment for these patients is non-surgical and the same as that for uncomplicated GERD. Surgery is indicated for sliding hiatal hernias that are unresponsive to medical therapy and large para-esophageal hiatal hernias.
The surgical procedure used to treat hiatal hernias (as well as severe GERD) is called the Nissen fundoplication. To plicate something is to fold it, and so a fundoplication is to fold the gastric fundus (Nissen is the surgeon who developed the procedure). Essentially, fundoplication involves taking the gastric fundus and wrapping it around the lower esophagus, securing it there with a stitch. This serves to reinforce the lower esophageal sphincter and bolster its function in preventing acid reflux (when the stomach contracts after a meal, it will contract around the lower esophagus helping to close it, rather than pushing stomach acid back up into it). The esophageal hiatus is then narrowed with a stitch to prevent recurrent herniation.
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