What is Acute Myocardial Infarction?

J.M. Willhite

An acute myocardial infarction is the disruption of proper blood flow to the heart muscle that results in damage to or the death of the muscle. Usually caused by a blockage within the coronary arteries that supply blood to the heart, myocardial infarction is considered a medical emergency. Treatment for this potentially life-threatening condition is dependent on its severity and cause and usually involves the administration of drugs to thin the blood and, in some cases, surgery to remove the arterial blockage.

Blood clots are a common cause of an acute myocardial infarction.
Blood clots are a common cause of an acute myocardial infarction.

Commonly known as a heart attack, an acute myocardial infarction is generally caused by the formation of a blood clot within a coronary artery that supplies the heart with oxygenated blood. Coronary blockages impair proper blood flow and, ultimately, deprive the heart muscle of oxygen. The deprivation forced upon the heart results in cell and tissue damage and, with time, can lead to the death of the heart muscle.

The buildup of plaque in coronary arteries may result in an acute myocardial infarction, and can require angioplasty surgery.
The buildup of plaque in coronary arteries may result in an acute myocardial infarction, and can require angioplasty surgery.

The buildup of plaque within the coronary arteries, also known as atherosclerosis, may also result in an acute myocardial infarction. The accumulation of plaque, composed of cholesterol and other fatty substances, narrows the arterial passages restricting proper blood flow. Over time, plaque accumulation may shift and crack, creating cavities in which blood may accumulate and form a clot, known as a thrombus.

Chest pain is the most common symptom associated with an acute myocardial infarction. Individuals may develop pain that is confined to a single part of the body or may experience widespread pain that radiates from the chest area to affect the torso, limbs, and back. Manifesting as mild to severe in intensity, chest pain associated with a heart attack may mimic the discomfort associated with indigestion or present as a constricting or heavy feeling that affects the entire chest area. Other symptoms associated with a heart attack include nausea, profuse sweating, and shortness of breath.

As a medical emergency, an acute myocardial infarction requires immediate medical attention. Once the individual is stabilized, a physical examination may be conducted and the attending physician may listen to the individual’s heart and lungs to determine the presence of any abnormalities. Additional testing is commonly ordered to evaluate the condition and functionality of the heart muscle following the attack.

A coronary angiography and computerized tomography (CT) scan may be performed to assess blood flow and the physical condition of the heart muscle. An electrocardiogram (ECG) may be employed every few hours to analyze the electrical conductivity of the heart. Additional imaging tests may also be ordered to further evaluate the heart muscle and may include an echocardiogram and magnetic resonance imaging (MRI). Blood tests are usually recommended to evaluate the extent of damage to the heart muscle and to check for any markers that may be indicative of risk for future heart problems.

Treatment for an acute myocardial infarction generally requires the individual to be hospitalized. Supplemental oxygen may be administered to stabilize blood oxygen levels and alleviate stress placed on the heart. There are many surgical procedures that may be utilized depending on the severity of the heart attack and its cause.

Emergency angioplasty surgery, known as percutaneous coronary intervention (PCI), may be performed within 90 minutes of the individual being brought to the emergency room. Used to open narrowed coronary arteries, PCI involves the placement of a stent in the blocked artery to re-establish proper blood flow to the heart muscle. Made of synthetic or metal mesh-like material, the stent remains in place to prevent the artery from closing. Some stents are equipped with medication that works as an anticoagulant to further reduce the chance for clot formation within the artery.

In some cases, medications alone may be administered to dissolve the blood clot that triggered the heart attack. Known as thrombolytic therapy, these medications are administered intravenously shortly after hospitalization. Additional blood thinning medication may be given orally to prevent further thrombus formation.

Coronary artery bypass surgery (CABG), also known as open heart surgery, may also be performed in the presence of severe coronary artery disease. During surgery, an artery or vein is taken from elsewhere within the individual’s body and repositioned to bypass the arterial blockage. The procedure may also be used if the individual possesses a significant narrowing of his or her main coronary artery that supplies most of the oxygenated blood necessary for proper heart function.

Complications associated with an acute myocardial infarction include shock, rupturing of the heart muscle, and blood clot formation within the lungs, or pulmonary embolism. Individuals who have suffered a heart attack may also develop congestive heart failure or pericarditis, which is an inflammation of the sac that encloses the heart. To reduce one’s risk for heart attack, individuals should exercise regularly, consume a balanced, healthy diet, and refrain from harmful habits, such as smoking.

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