Myocardial infarction; MI; heart attack
A disorder in which damage to an area of heart muscle occurs because of an inadequate supply of oxygen to that area.
Common causes, incidence, and risk factors
Causes include clot formation or spasm in one of the arteries that supply the heart muscle (a coronary artery). These and other similar conditions block the supply of oxygen to an area of the heart, leading to damage or death of the cells in that area. Most often, this occurs in a coronary artery that has been narrowed from changes related to atherosclerosis. The damaged tissue results in a permanent loss of contraction of this portion of the heart muscle.
Risk factors for MI include smoking, hypertension, diabetes mellitus, high fat diet, high blood cholesterol (LDL) levels, obesity, male gender, age over 65, and heredity. A personal or family history of coronary artery disease, cerebrovascular disease, peripheral vascular disease, angina (particularly unstable angina), or kidney failure requiring hemodialysis indicates increased risk for MI. Occasionally, sudden overwhelming stress can trigger an MI, but this is rare. In older persons, straining to have a bowel movement can be a risk factor.
Chest pain is the cardinal symptom of MI, but in many cases the pain may be subtle or even completely absent, especially in the elderly and diabetics. Other symptoms such as weakness, shortness of breath, nausea, or vomiting may predominate.
Acute MI occurs in approximately 2 out of 1,000 people per year. It is a major cause of sudden death in adult.
Control cardiac risk factors whenever possible. Control blood pressure and total cholesterol levels, reduce or avoid smoking, modify diet (increase high density lipoproteins & decrease low density lipoproteins) if necessary, control diabetes, lose weight if obese. Follow an exercise program to improve cardiovascular fitness. (Consult the health care provider first.)
After an MI, followup care is important to reduce the risk of developing a new MI. Often, a cardiac rehabilitation program is recommended to aid in gradual return to a "normal" lifestyle. Follow the exercise, diet, and/or medication regimen prescribed by your doctor.
Pain that may be described as:
Shortness of breath
Additional symptoms that may be associated with this disease:
Examination often reveals a rapid pulse. Blood pressure may be normal, high, or low. Listening to the chest with a stethoscope (auscultation) may show crackles in the lungs, heart murmur, or other abnormal sounds.
Indications of MI and extent of heart damage may show on the following tests:
Byproducts of heart damage and factors indicating high risk for MI may show on the following tests:
This disease may also alter the results of the following tests:
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