How Ischemia Affects Different Parts of the Body

Ischemia is a condition in which there is insufficient blood flow to a part of the body. It is often caused by plaque building up and thickening or hardening the artery supplying that area or organ. The body part subjected to ischemia is referred to as being ischemic.

Common examples of ischemia include:

• Cardiac ischemia (affecting the heart)
• Brain ischemia
• Intestinal ischemia
• Limb ischemia (affecting an arm or leg)

This article explains ischemia, including what it does, what causes ischemia in different parts of the body, how it is diagnosed, and what treatments are available.

What Is Ischemia?

Ischemia happens because the blood supply to a part of the body is cut off—for example, by a blood clot or another type of blockage, restriction, or malformation.

When a part of the body is ischemic, it is not receiving all the oxygen and nutrients it needs. Ischemia usually causes an affected organ to malfunction, and it often produces symptoms.

If the ischemia becomes severe enough or persists long enough, the cells of the affected area may begin to die. The death of all or part of an ischemic organ is called an infarction.

Ischemia Causes

The cause of ischemia can be related to the specific part of the body that's affected, but there are also some general risk factors that apply more broadly, such as:

• Having a condition that makes your blood more likely to clot
• Having poor circulation or blood pressure problems (too high or too low)
• Lifestyle factors like smoking, using certain drugs, taking certain medications, not having a nutritious diet, having obesity, and being sedentary
• Having certain medical conditions like heart disease, diabetes, and stroke
  

Cardiac Ischemia

Ischemia can affect the heart. When this happens, it's called cardiac ischemia. Also called myocardial ischemia, ischemia of the heart is most often caused by atherosclerotic plaques in the coronary arteries, the arteries which supply the heart muscle. However, cardiac ischemia may also result from other conditions such as coronary artery spasms, cardiac syndrome X (also called coronary microvascular disease), or congenital anomalies of the coronary arteries.

Stable angina is the symptom of chest (or upper body) discomfort caused by cardiac ischemia precipitated by exercise or stress. It's called "stable" because the triggers and course are generally predictable. The symptoms usually abate with rest or relaxation.

Unstable angina, on the other hand, occurs without any relation to exercise or stress. It comes as a surprise and usually doesn't get better with rest. Unstable angina is often a feature of acute coronary syndrome—a medical emergency.

Brain Ischemia

When ischemia affects the brain, it can lead to serious consequences. Brain tissue is metabolically very active, and in order to function properly, the brain receives 20% of the blood pumped by the heart. Furthermore, unlike many other organs, the brain has no energy stores of its own and is completely dependent on continuous blood flow to do its work. Consequently, brain tissue rapidly becomes ischemic if blood flow is interrupted, and unless the blood flow is rapidly restored brain death quickly ensues. The death of brain tissue is called a stroke.

Sometimes the blood flow to a portion of the brain is interrupted long enough to produce symptoms of brain ischemia, but not long enough to produce an actual stroke. This condition is called a transient ischemic attack (TIA). A TIA can duplicate any of the many varieties of stroke symptoms except that the symptoms resolve within a few hours. TIAs are important not only because they are alarming in themselves, but also because they are often followed by a full stroke. Thus, TIAs always require immediate medical attention.

Intestinal Ischemia

Ischemia in the gastrointestinal tract is called intestinal ischemia or mesenteric ischemia. This type of ischemia occurs in the blood vessels supplying the intestinal organs.

Chronic intestinal ischemia, which is usually produced by atherosclerosis of the intestinal arteries, typically causes recurrent symptoms after a meal, when the intestines are trying to perform their digestive work in the face of insufficient blood supply. Intestinal ischemia most often causes abdominal pain (referred to as intestinal angina) following a meal, especially a fatty meal.

Symptoms of intestinal angina include pain in the upper abdomen, though it can radiate to the back. Intestinal angina usually persists for about two to three hours, but then consistently returns after another meal.

Acute intestinal ischemia may occur when an embolism (blood clot) lodges in the intestinal arteries. These blood clots most commonly originate in the heart, as a result of atrial fibrillation. If the embolism is severe enough, intestinal infarction (death of a portion of the intestine) can result. Intestinal infarction is a medical emergency.

Limb Ischemia

Ischemia that involves your arms or legs is called limb ischemia. This type of ischemia is common in people with peripheral artery disease (PAD), a form of atherosclerosis that affects the arteries supplying the arms or legs (most typically, the legs).

The most common syndrome seen with limb ischemia is intermittent claudication, a type of cramping pain, usually affecting one leg, that occurs reproducibly after a fixed amount of walking. PAD is often treated with angioplasty and stenting, although bypass surgery is also commonly required.

Summary

Ischemia is a condition that happens when the blood supply to a part of the body is cut off. Ischemia can happen to your heart, limbs, gastrointestinal tract, and even your legs. Your risk for ischemia might be higher if you have certain health conditions or lifestyle factors, but you can't always prevent ischemia from happening.