• Electrocardiogram

    (ECG; EKG)


    An electrocardiogram (ECG or EKG) measures the electrical activity of your heart. The heart generates an electrical signal, which flows out from your heart through your body. Small electrical sensors, called electrodes, are put on your skin to sense the electricity that began in your heart. The electrical activity is then turned into a graph. This can give doctors an idea of whether your heart is beating normally.
    ECG/EKG Waves
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    Copyright © Nucleus Medical Media, Inc.

    Reasons for Test

    An ECG is used to:
    • Diagnose heart attacks and rhythm problems
    • Offer clues about other heart conditions and conditions not primarily related to the heart
    • Detect conditions that alter the body’s balance of electrolytes (such as potassium and magnesium)
    • Detect other problems, such as overdoses of certain drugs
    Symptoms that may prompt an ECG include:
    • Chest discomfort or pain
    • Shortness of breath
    • Palpitations (fast heartbeats)
    • Anxiety
    • Weakness
    • Nausea or the feeling that you have to vomit
    • Abdominal pain
    • History of fainting
    • Taking certain drugs
    An ECG may also be obtained if you:
    • Are about to have surgery with general anesthesia—to detect heart conditions that could worsen during surgery and put you at risk
    • Are in occupations that stress the heart or where public safety is a concern
    • Are an older adult or have diabetes—to obtain a record to compare with future ECGs
    • Already have heart disease—to check occasionally for any changes
    • Have had a heart-related procedure, such as getting a pacemaker

    Possible Complications

    There are no major complications associated with this test.

    What to Expect

    Prior to Test

    You may:
    • Have a physical exam and be asked about your medical history
    • Have your chest shaved if needed

    Description of Test

    You will be asked to lie quietly on your back with your shirt off. Six small, sticky pads with attached wires will be placed across your chest. Others will be placed on your arms and legs. The wires will connect to the ECG machine. You will not feel anything during the test.

    After Test

    You may resume activities as recommended by your doctor.

    How Long Will It Take?

    3-4 minutes

    Will It Hurt?



    Your doctor will interpret the ECG. Based on the results and your other health information, you may need more tests or a treatment plan.

    Call Your Doctor

    After the test, call your doctor if you have heart-related symptoms, like chest pain or trouble breathing.


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

    American Medical Association http://www.ama-assn.org

    Heart Rhythm Society http://www.hrsonline.org


    Canadian Cardiovascular Society http://www.ccs.ca

    Heart and Stroke Foundation of Canada http://ww2.heartandstroke.ca


    Diagnostic tests: electrocardiogram. The Harvard Medical School Family Health Guide website. Available at: http://www.health.harvard.edu. Accessed June 11, 2008.

    Electrocardiogram. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/electrocardiogram/HB00014. Updated June 2006. Accessed June 11, 2008.

    Electrocardiogram. University of Michigan website. Available at: http://www.med.umich.edu/1libr/aha/aha%5Felecgram%5Fcar.htm. Updated April 2006. Accessed November 15, 2006.

    Electrocardiogram (EKG or ECG). American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=3005172. Updated March 2008. Accessed July 21, 2009.

    Exercise electrocardiogram (stress test). Heart and Stroke Foundation website. Available at: http://www.health.harvard.edu. Updated September 2006. Accessed June 4, 2008.

    Kasper DL, Braunwald, E, Fauci AS, Hauser SL, Longo DL, Jameson JL. Harrison’s Principles of Internal Medicine. 16 ed. New York, NY: McGraw-Hill Professional; 2004.

    Revision Information

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