infarction, blockage of blood circulation to a localized area or organ of the body resulting in tissue death. Infarctions commonly occur in the spleen, kidney, lungs, brain, and heart. The acute emergency known as myocardial infarction or heart attack is usually caused by a blockage in one of the coronary arteries that supply blood to the heart muscle. The blockage typically occurs when a blood clot (see thrombosis) lodges in an area already narrowed by arteriosclerosis; other causes are vasospasms in the arterial walls or viral infection of the heart. Symptoms include a crushing pain in the chest radiated to either arm (more commonly the left arm), the jaw, and the neck. The pain may be experienced, particularly in women, as pain in the shoulder or stomach, instead of the chest, and in some cases there are no symptoms at all. The seriousness of the infarction is dependent upon the amount of heart muscle affected, how long the area is deprived of blood, and whether it affects the natural pacemaker of the heart, setting off arrhythmias such as ventricular fibrillation. Death of heart muscle tissue and heart failure may result (see congestive heart failure); damage to other vital organs, including the brain, may occur if the heart is unable to pump necessary oxygen and blood to them. Confirmation of myocardial infarction is made by electrocardiography and measurement of elevations of white blood cells and certain enzymes. Treatment of acute myocardial infarction may include first aid in the form of cardiopulmonary resuscitation (CPR), an emergency balloon angioplasty, or the administration of beta-blockers and thrombolytic drugs (clot-dissolving drugs), such as tissue plasminogen activator. The healing of an infarction occurs through replacement of the dead tissue by scar tissue.

See also coronary artery disease.

or myocardial infarction

Death of a section of heart muscle when its blood supply is cut off, usually by a blood clot in a coronary artery narrowed by atherosclerosis. Hypertension, diabetes mellitus, high cholesterol, cigarette smoking, and coronary heart disease increase the risk. Symptoms include severe chest pain, often radiating to the left arm, and shortness of breath. Up to 20percnt of victims die before reaching the hospital. Diagnosis is done by electrocardiography and by analysis for enzymes in the blood. Treatment aims to limit the area of tissue death (infarct) and prevent and treat complications. Thrombolytic (clot-dissolving) drugs may be administered. Beta-blockers alleviate pain and slow the heart rate. Angioplasty or coronary bypass restores blood flow to heart muscle. Follow-up may include drugs, exercise programs, and counseling on diet and lifestyle changes.

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In medicine, an infarction is the process resulting in a macroscopic area of necrotic tissue in some organ caused by loss of adequate blood supply. Supplying arteries may be blocked from within by some obstruction (e.g. a blood clot or fatty cholesterol deposit), or may be mechanically compressed or ruptured by trauma.

Infarction is commonly associated with atherosclerosis, where an atherosclerotic plaque ruptures, a thrombus forms on the surface occluding the blood flow and occasionally forming an embolus that occludes other blood vessels downstream. Infarction can also involve mechanical blockage of the blood supply, such as when part of the gut herniates or twists.

Classification

Infarctions are divided into two types according the amount of hemorrhaging present:

• White infarctions (anemic infarcts) affect solid organs such as the heart, spleen, and kidneys. The occlusion is most often composed of platelets, and the organ becomes white, or pale.
• Red infarctions (hemorrhagic infarcts), generally affecting the lungs. The occlusion consists more of red blood cells and fibrin strands.

Diseases

Diseases commonly associated with infarctions include:

• Myocardial infarction (heart attack)
• Pulmonary embolism ("lung attack")
• Cerebrovascular accident (stroke – 80% are due to infarction)
• Peripheral artery occlusive disease (the most severe form of which is gangrene)
• Antiphospholipid syndrome
• Sepsis
• Giant-cell arteritis (GCA)
• Hernia
• Volvulus