A myocardial infarction is also known as a heart attack, occurs when blood flow decreases or stops to a part of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw. Often it occurs in the center or left side of the chest and lasts for more than a few minutes. The discomfort may occasionally feel like heartburn. Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat or feeling tired. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest.[
Most MIs occur due to coronary artery disease. Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet and excessive alcohol intake. The complete blockage of a coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mechanism of an MI. MIs are less commonly caused by coronary artery spasms, which may be due to cocaine, significant emotional stress and extreme cold, among others. A number of tests are useful to help with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography. An ECG, which is a recording of the heart's electrical activity, may confirm an ST elevation MI (STEMI), if ST elevation is present. Commonly used blood tests include troponin and less often creatine kinase MB.
- Chest pain, upper extremity pain, mandibular, or epigastric discomfort that occurs during exertion or at rest and is usually not affected by positional changes or active movement of the region. Chest pain (usually retrosternal), sometimes described as the sensation of pressure or heaviness.
- Pain radiating to the left shoulder, neck, or arms and it may be intermittent or persistent.
- Dyspnea or fatigue.
- Pain lasting more than 20 minutes
- Additional symptoms, such as sweating, nausea, abdominal pain, dyspnea, and syncope, may also be present.
- Atypical with subtle findings such as palpitations
Myocardial Infarction Causes
The causes of myocardial infarction, or a heart attack, all involve some kind of blockage of one or more of the coronary arteries.
- Atherosclerosis is also known as coronary artery disease, this condition is the most common cause of heart attacks and occurs when the buildup of fat, cholesterol, and other substances forms plaque on the walls of the coronary arteries. If one of these plaques ruptures, a blood clot will form on top of the ruptured plaque like a scab. A blood clot that is large enough can completely block the flow of blood through an artery, triggering a heart attack.
- Coronary artery spasm is a rare cause of blockage, spasms of the coronary arteries can cause them to become temporarily constricted
Journal of Stroke Research & Therapy.