Heart attack

A heart attack—also called myocardial infarction or MI—occurs when an area of heart muscle is completely deprived of blood, and the heart muscle cells die.

A heart attack may result when plaque inside the heart arteries breaks open or ruptures, forming a clot that significantly blocks blood flow through the artery.

A plaque is made up of cholesterol, white blood cells, calcium, and other components, and it is surrounded by a fibrous cap. This fibrous cap may tear or rupture if blood suddenly flows faster, or the artery suddenly narrows. A tear or rupture signals the body to repair the injured artery lining, much as it might heal a cut on the skin, by forming a blood clot to seal the area. A blood clot that forms in an artery can completely block blood flow to the heart muscle and cause a heart attack.

The pain of a heart attack often occurs with other symptoms, including:

  • Chest discomfort or pain that may be crushing or squeezing or may feel like a heavy weight on the chest.
  • Chest discomfort or pain that occurs with:
    • Sweating.
    • Shortness of breath.
    • Nausea or vomiting.
    • Pain that spreads from the chest to the neck, the jaw, or one or both shoulders or arms.
    • Dizziness or lightheadedness.
    • A fast or irregular heartbeat.
    • Loss of consciousness.

The pain of a heart attack usually will not go away with rest.

It is important to recognize the early stages of a heart attack and to seek emergency care. Medical treatment is needed to prevent death. Sometimes medicines can be given to reduce the damage to the heart muscle caused by a heart attack.

Last Updated: May 5, 2009

Author: Robin Parks, MS

Medical Review: Caroline S. Rhoads, MD - Internal Medicine & John A. McPherson, MD, FACC, FSCAI - Cardiology

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