Abdominal Angina (Intestinal Pain)

What is abdominal angina?

Abdominal angina is a type of abdominal pain that starts after eating (postprandial pain) as the blood flow to the bowels are insufficient to for the increased demands. The bowels are essentially starved of oxygen eventually leading to damage and even tissue death over time. It is an uncommon condition and more commonly seen in females after the age of 60 years. Although the condition is fairly well understood and can be effectively treated with surgery, the chance of death is very high without prompt medical attention.

Abdominal angina reasons

After eating, the gut becomes highly active to move and digest food and absorb nutrients. This requires an increase in blood flow. The three main arteries that carry blood to the gut includes the :

celiac artery
superior mesenteric artery
inferior mesenteric artery

If these arteries are narrowed in any way then the blood flow to the gut is insufficient for its activities after eating food. Atherosclerosis, a process where the artery becomes narrow and hardened, impedes the greater blood flow. This causes injury to the gut tissue known as bowel ischemia although the damage is usually reversible. Should a blood clot suddenly block this already narrowed artery then the tissue of the affected part of the gut can become severely damaged and even die – infarct.

Normally the blood supply is not severely compromised if just one of these arteries are affected. The other two arteries can compensate or any smaller blood vessels (collateral supply) can ensure adequate blood flow to prevent major tissue damage. However, when two or more of the arteries are very narrow or blocked then the tissue of the gut is damaged and may die. The superior mesenteric artery is one of the more significant sites of a problem as it supplies a wide area of the gut and even a collateral supply cannot compensate when it is blocked.

Abdominal angina vs chest angina

The term angina is often associated with the heart – cardiac pain that is brought about with activity. It typically presents as central chest pain that radiates to the neck, jaw, arm or even upper abdomen.This concept is similar to what happens with the bowels in abdominal angina. However, cardiac (heart) angina and abdominal angina are two different entities despite the problems with the blood vessels of the respective organs being largely affected in the same way.

In chest angina, the blood supply to the heart wall is insufficient to compensate with its demands. When the heart has to beat faster, like during periods of exercise, then the narrowed artery cannot deliver sufficient blood to the heart muscle. This leads to cardiac ischemia – tissue damage with reduced blood flow. It is essentially the same process with the bowels. Increased activity of the gut after eating food brings about the pain as the blood supply to the gut is inadequate for its needs. Despite the differences in organs, it is interesting to note that eating a heavy meal could be a trigger for cardiac angina just as strenuous exercise could be a trigger for abdominal angina.

Abdominal angina causes

Abdominal angina is caused by narrowing and then blockage of the artery or arteries of the gut. It is not uncommon for the patient to have similar problems elsewhere in the body – heart (cardiac angina) or legs (peripheral artery disease).

Narrowed arteries

Although the process of atherosclerosis is well understood, it is unclear why some people are more affected than others. Genetic factors may play a role. Cigarette smoking is by far the most significant risk factor with about 3 out of 4 people suffering abdominal angina being smokers. However, there is the associated component of high blood pressure and elevated blood cholesterol levels in smokers who are at the greatest risk. The inner lining of the artery is damaged, fatty plaques form inside the artery wall and the artery becomes hard and narrow. Blood flow is restricted but usually not blocked entirely.

Blood clot blockage

It is usually a blood clot that blocks the narrowed artery. These clots may form at the site and is then known as a thrombus. Alternatively it may form elsewhere in the body, breaks off and travels through the bloodstream to block the narrowed artery. In this case it is known as an embolus. Although a blood clot is the most common type of embolus, sometimes fat globules, cancer cells and even pieces of plastic can cause the blockage if it is in the bloodstream. Most of the blood clots that cause the blockage of the bowel arteries are from the heart and aorta. Therefore a person with conditions such as an arrhythmias (irregular heart rhythm) is at greater risk as a clot if more likely to form in this instance.

Abdominal angina symptoms

Abdominal pain is the hallmark of abdominal angina. However, abdominal pain is a non-specific symptom meaning that it can be due to a host of different conditions and does not clearly indicate the underlying cause. Certain characteristics of the pain in abdominal angina may provide a better indication of the condition.

Location of pain

The pain in abdominal angina is typically described as being located within the upper middle abdominal area (epigastric region) or in the center of the abdomen. However, it is not always so well localized and some patients may describe a generalized abdominal pain and not be able to isolate it to a specific region.

Duration of pain

The pain tends to start about 10 to 15 minutes after eating as bowel activity increases. It may then persist for several hours thereafter although the pain worsens, reaches a plateau and begins to subside in that time. Sometimes the pain is intermittent and not constant but this is largely dependent on the degree of the blockage and the collateral blood supply.

Pain and meal size

In the early stages, the pain is triggered only by large meals. Small meals are fairly well tolerated and this is one of the reasons a person starts to eat less. As the condition worsens, even small meals can trigger intense pain. At this point a person develops a fear of food and will skip meals and eat the bare minimum.

Other symptoms

Nausea
Vomiting
Bloating
Constipation or diarrhea
Weight loss

Abdominal angina diagnosis

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The symptoms, particularly the location, duration and nature of the pain after eating, along with the patient’s medical history may raise the suspicion of abdominal angina but not confirm it. Blood tests are of little use except if the pancreas is also affected. The degree of the obstruction needs to be visualized with certain imaging techniques.

Biplane aortography is the preferred investigative method. Here a radiocontrast dye is delivered into the aorta and x-rays are taken. Since the dye will not allow x-rays to pass through, the arteries can be seen. Any narrowing or obstruction is then made obvious.
Duplex ultrasonography is another option for diagnosing the condition by the use of ultrasound waves.
Magnetic resonance imaging (MRI) is also a useful tool where a combination of magnetic and radio waves are used to visualize the internal structures of the body.

Abdominal angina treatment

There is no medication to treat abdominal angina. Drugs to widen the vessels and break down clots are of limited use. Surgery is necessary. The surgical procedures in the treatment of abdominal angina are not significantly different from that for coronary artery disease (CAD) and a myocardial infarction (heart attack). There are basically three options :

Widening the narrowed artery.
Cutting the artery and removing the obstruction.
Bypassing the narrowed artery.

These procedures can be done endoscopically or trhough open surgery.

Angioplasty and Stent

A catheter is inserted into the aorta.
A guide wire is then directed to the narrowed artery of the gut.
A balloon in the dilator portion is then inflated to widen the artery.
A stent may then be inserted if the narrowing is still significant after balloon dilation.

Arteriotomy and Embolectomy

This is an open surgery where the artery wall is cut (arteriotomy) and the site of the blockage identified. The embolus blocking the artery is then removed (embolectomy). The plaques in the artery are also removed to undo the narrowing of the artery. Depending on the type of incision that is made in the artery wall, a patch may be used to close the site.

Bypass

This is also an open surgery where a new conduit for blood flow is established around the obstruction. A vein from the patient (graft) is used as the new conduit.

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