Myocardial ischemia – Symptoms and causes
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.
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 tissue is metabolically very active, and in order to function properly, the brain receives 20 percent 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 (also called mesenteric ischemia) occurs with the 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.
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, although bypass surgery is also commonly required.