How Ischemia Affects Different Parts of the Body

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Ischemia is a condition in which there is insufficient blood flow to one of the body’s organs, most often caused by an atherosclerotic plaque in the artery supplying that organ. An organ subjected to ischemia is referred to as being ischemic.

Because an ischemic organ is not receiving all the oxygen and nutrients it needs, ischemia usually causes the affected organ to malfunction, and often, to produce symptoms.

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

Common examples of ischemia include the following:

Cardiac Ischemia

Cardiac ischemia 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 spasm, cardiac syndrome X, or congenital anomalies of the coronary arteries.

“Typical” angina is the symptom of chest (or upper body) discomfort caused by cardiac ischemia precipitated by exercise or stress. The symptoms usually abate with rest or relaxation.

“Atypical” angina, or unstable angina, usually occurs without any relation to exercise or stress and is often a feature of acute coronary syndrome - a medical emergency.

Brain Ischemia

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

Intestinal ischemia (also called mesenteric ischemia) occurs with disease 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 an insufficient blood supply. Intestinal ischemia most often causes abdominal pain (referred to as intestinal angina) following a meal, especially a fatty meal.

Intestinal angina is a dull and crampy pain near the pit of the stomach, though it can radiate to the back. Intestinal angina usually persists for about two hours, but then 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 of the limbs can occur 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, though bypass surgery is also commonly required.

Sources

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Rooke TW, Hirsch AT, Misra S, et al. Management of patients with peripheral artery disease (compilation of 2005 and 2011 ACCF/AHA Guideline Recommendations): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2013; 61:1555.

Easton JD, Saver JL, Albers GW, et al. Definition and evaluation of transient ischemic attack: a scientific statement for healthcare professionals from the American Heart Association/American Stroke Association Stroke Council; Council on Cardiovascular Surgery and Anesthesia; Council on Cardiovascular Radiology and Intervention; Council on Cardiovascular Nursing; and the Interdisciplinary Council on Peripheral Vascular Disease. The American Academy of Neurology affirms the value of this statement as an educational tool for neurologists. Stroke 2009; 40:2276.

Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation 2012; 126:e354.

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