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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.

Author Jeannette Curtis
Author Caroline Rea, RN, BS, MS
Editor Kathleen M. Ariss, MS
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Tracy Landauer
Associate Editor Pat Truman
Primary Medical Reviewer Patrice Burgess, MD
- Family Medicine
Primary Medical Reviewer Adam Husney, MD
- Family Medicine
Primary Medical Reviewer Kathleen Romito, MD
- Family Medicine
Last Updated May 25, 2007

WebMD Medical Reference from Healthwise

Last Updated: May 25, 2007
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.