Causes Of Acid Reflux

Acid Reflux and Hernia

The anatomical features of the gastroesophageal junction play a very important role in the development of GERD.

hiatal hernia graphic
Graphic of how a hiatal hernia fomrs

When the gastroesophageal junction is not functioning correctly, clearance of acid from the esophagus is less efficient; this happens in men and women who have hiatal hernia.

So what we can therefore reasonably assume is that the presence of a hiatal hernia may promote the development of acid reflux and GERD (gastroesophageal reflux disease). Research on the subject.

Of course not everyone with a hiatal hernia actually develops symptoms of acid reflux, so a better understanding of the connection between these is long overdue and will be very helpful in treatment.

For some time, the presence of a hiatal hernia was regarded as an essential element of the development and diagnosis of GERD, and the two terms became almost synonymous.

acid reflux diagram
representation of acid reflux

More recently, however, anatomical studies have given way to functional studies of the lower esophageal sphincter (LES), focusing on the efficiency and pressure that it exerts rather than its anatomy.

In other words, instead of thinking that the anatomical abnormality of a hiatal hernia causes GERD, the medical profession now see the low pressure exerted by the lower esophageal sphincter as one of the primary factors behind GERD.

But the link is not simple. For one thing, the resting pressure of the LES is only one component of the functioning of this valve.

We know that the lower esophageal sphincter often shows transient relaxation that is not associated with swallowing. These transient episodes of relaxation are now also regarded as a major reason behind symptoms of GERD.

In short, current understanding is that both the presence of a hiatal hernia and functional abnormality of the lower esophageal sphincter can be independent factors in the development of acid reflux.

So what then, is the current view of the role of the hiatal hernia in the development of GERD? The answer seems to be that when the gastroesophageal junction malfunctions, it’s because there is an imbalance between factors which promote acid reflux and those which defend against it.

Clearly, the gastroesophageal junction is the first line of defense against acid reflux, and any failure of function or anatomy can contribute to this reflux.

The gastroesophageal junction is not simple and nature; it is composed of part of the lower esophageal sphincter and part of the diaphragm, and both the correct function and the correct anatomy of all these components are necessary for its correct operation.

For example, the angle of His, which is the angle between the stomach and esophagus, needs to be sufficiently acute, as does the tension and elasticity in the phrenoesophageal ligament.

The LES is composed of the lowest 3 or 4 cm of the esophagus, which is contracted when at rest.

Normally the pressure exerted by the resting loweroesophageal sphincter is slightly higher than the pressure inside the stomach, although the muscle tone varies considerably from moment to moment.

The muscle tone is affected significantly by many different factors such as hormones, food, drugs and so forth.

When reflux is occurring regularly, what is known is that the gastroesophageal junction is not functioning for one of three reasons:

  • transient relaxation,
  •  its resting tone is too low, or
  • there is an anatomical problem such as a hiatal hernia.

Any of these can cause acid reflux, although transient LES relaxations tend to give rise to less severe GERD than does a hiatal hernia.

A hiatal hernia is a condition where part of the stomach and the gastroesophageal junction is displaced upwards into the thoracic cavity.

The hiatus in the diaphragm through which the esophagus normally passes is sufficiently large to allow a small portion of the stomach and gastroesophageal junction to rise upwards, or herniate, during swallowing. They are, or should be, brought back into their normal position by the elastic recoil of the phrenoesophageal ligament, which is attached at one end to the esophagus, and at the other to the esophageal hiatus in the diaphragm.

Should this ligament become loose or inelastic, because of increased abdominal pressure, surgery, a genetic predisposition, or simply the wear and tear of aging, the ligament no longer returns that portion of the stomach and gastroesophageal junction which moves through the hernia to its correct place.

It would seem therefore that a hiatal hernia can cause acid reflux.

However, some studies have suggested that rather than a hiatal hernia causing GERD, the opposite relationship applies: that reflux is itself sufficiently damaging to the esophagus to enable it to cause esophageal shortening, thereby pulling the gastroesophageal junction upwards through the hiatus in the diaphragm.

Diagnosis, Clinical Significance & Treatment Of Hiatal Hernia

Diagnosis of hiatal hernia is made by one or more of several investigative methods. These include barium X-rays, endoscopy, and pressure measurements.

Barium X-ray swallows, or contrast studies, demonstrate that a structure known as the phrenic ampulla is seen above the diaphragm when an individual swallows.

This has been a traditional method of diagnosing hiatal hernia, but has recently been found to be both inconsistent and inaccurate, and has now been replaced to a large extent by endoscopy.

Even here there is a degree of controversy about which portion of the esophagus should be used as a marker to define hiatal hernia.

The squamocolumnar junction (SCJ) is the circumferential tissue around the esophagus which is bordered by the squamous epithelium of the esophagus and the orange colored columnar epithelium of the stomach.

Since this area usually corresponds to the gastroesophageal junction, it’s been used as a marker of hiatal hernia.

However, in the case of Barrett’s esophagus, the SCJ is not in the normal place, so other methods of identifying the gastroesophageal junction must be found.

This uncertainty is reflected in the fact that when different doctors conduct an investigation, there can be considerable differences between their diagnoses as to the severity of an individual’s hiatal hernia.

Having said all of that, an experienced doctor will generally be able to recognize a hiatal hernia, particularly when using manometry, since accurate manometric assessments can clearly distinguish between sliding and paraesophageal hiatal hernias.

So we know that hiatal hernia is closely related to reflux symptoms, reflux esophagitis, and Barrett’s esophagus.

We also know that those people with a hiatal hernia are more likely to develop GERD than those without. Indeed, over half of men and women with reflux esophagitis have a hiatal hernia.

(Although, as mentioned previously, a significant number of people without acid reflux also have a hiatal hernia.)

But the presence of a hiatal hernia itself is not necessarily an indication that treatment is necessary. Indeed, some believe that treatment should be given only to those with symptoms of acid reflux – which seems a perfectly reasonable viewpoint!

For those without symptoms of acid reflux, who happen to have a diagnosis of hiatal hernia made for some other reason, lifestyle modifications and medication may be offered.

Surgery for hiatal hernia is not generally necessary, but may be offered to those individuals who do not wish to take drugs for prolonged periods of time or who do not respond to medical therapy.

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