Heart Attack

(Myocardial Infarction)

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Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention | Organizations

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Definition

A heart attack occurs when blood flow to the heart muscle is interrupted. This deprives the heart muscle of oxygen, causing tissue damage or tissue death.

Causes

A heart attack may be caused by:

• Thickening of the walls of the arteries feeding the heart muscle (coronary arteries)
• Accumulation of fatty plaques in the coronary arteries
• Narrowing of the coronary arteries
• Development of a blood clot in the coronary arteries

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

• Sex: Male
• Increased age
• Obesity
• Smoking
• High blood pressure
• Sedentary lifestyle
• High blood cholesterol (specifically, high LDL cholesterol, and low HDL cholesterol)
• High blood triglycerides
• Diabetes
• Stress
• Family members with heart disease

Symptoms

Symptoms include:

• Squeezing, heavy chest pain, especially with:
  • Exercise or exertion
  • Emotional stress
  • Cold weather
  • A large meal
• Pain in the left shoulder, left arm, or jaw
• Shortness of breath
• Sweating, clammy skin
• Nausea
• Weakness
• Loss of consciousness

Unusual symptoms of heart attack (may occur more frequently in women):

• Stomach pain
• Back pain
• Confusion
• Fainting

Diagnosis

If you think you are having a heart attack, call 911 immediately. You need emergency medical care.

Tests may include:

Blood Tests – to look for certain substances found in the blood within hours or days after a heart attack. Blood tests will be repeated every 6-8 hours to track the progressive elevation of certain enzymes that indicate heart muscle damage.

Urine Tests – to look for certain substances found in the urine within hours or days after a heart attack

Electrocardiogram (EKG) – records the heart's activity by measuring electrical currents through the heart muscle. Certain abnormalities in the EKG occur when there is significant blockage of the coronary arteries and/or damage to the heart muscle. The EKG will be repeated to track the progression of these changes.

Echocardiogram – uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart

Stress Test – records the heart's electrical activity under increased physical demand

Thallium Stress Test – thallium is used to scan the myocardium, the middle layer of the heart

Nuclear Scanning – radioactive material is injected into a vein and observed as it is absorbed by the heart muscle

Electron-beam CT scan – a type of x-ray that uses a computer to make pictures of the heart and surrounding structures

Coronary Angiography – x-rays taken after a dye is injected into the arteries; to look for abnormalities in the arteries

Treatment

Treatment may include:

• Oxygen
• Pain-killing medications (such as morphine)
• Nitrate medications
• Atropine
• Beta-blocking and/or ACE inhibitor medications
• Anti-anxiety medications
• Clot-busting agents: within the first six hours after a heart attack, you may be given medications to break up blood clots in the coronary arteries. These include:
  • Tissue plasminogen activator (tPA)
  • Streptokinase
  • APSAC

Surgery

Surgeries for people with severe blockages in their coronary arteries may include:

• Coronary bypass graft
• Atherectomy
• Balloon angioplasty with or without stenting

Physical or Rehabilitative Therapy

During recovery from a heart attack, you may need physical or rehabilitative therapy to help you regain your strength.

Psychotherapy or Antidepressant Medication

Some people have depression after suffering a heart attack. If you do, psychotherapy and/or antidepressant medications may help relieve depression.

Prevention

Preventing or treating coronary artery disease may help prevent a heart attack.

• Maintain a healthy weight.
• Begin a safe exercise program with the advice of your doctor.
• If you smoke, quit.
• Eat a healthful diet, one that is low in saturated fat and rich in whole grains, fruits, and vegetables.
• Appropriately treat high blood pressure and/or diabetes.
• Ask your doctor about taking a small, daily dose of aspirin. It has been shown to decrease the risk of heart attack.
• Ask your doctor about taking cholesterol-lowering medications.
• Ask your doctor about taking nitrate medications if you have angina due to coronary artery disease.
• Ask your doctor about taking medication to improve heart function, such as:
  • Beta-blockers
  • Ace-inhibitors
  • Calcium-channel blockers
  • Digitalis-type drugs

Organizations

American Heart Association
http://www.americanheart.org

American Medical Association
http://www.medem.com

SOURCES:

Conn's Current Therapy 2001, 53rd ed. W. B. Saunders Company, 2001.

American Heart Association

American Medical Association

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Last reviewed June 2001 by Medical Review Board