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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.

EKG Waves
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Reasons for Test

An EKG is used to:

  • Diagnose heart attacks and rhythm problems
  • Offer clues about other heart conditions and conditions not directly related to the heart
  • Detect conditions that change 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 EKG include:

  • Chest discomfort or pain
  • Shortness of breath
  • Palpitations
  • Anxiety
  • Weakness
  • Nausea
  • History of fainting

An EKG may also be obtained if you:

  • Are about to have surgery with general anesthesia
  • Are in occupations that stress the heart or where public safety is a concern
  • Are an older adult or have diabetes
  • Already have heart disease
  • 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
  • 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 EKG 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 EKG. Based on the results and your other health information, you may need more tests or a treatment plan.

Call Your Doctor

Call your doctor if you have heart-related symptoms, such as chest pain or trouble breathing.

If you think you have an emergency, call for emergency medical services right away.

Revision Information

  • American Heart Association

  • Heart Rhythm Society

  • Canadian Cardiovascular Society

  • Heart and Stroke Foundation of Canada

  • Electrocardiogram (EKG or ECG). American Heart Association website. Available at: Updated November 26, 2012. Accessed March 11, 2015.

  • Noninvasive tests and procedures. American Heart Association website. Available at: Updated April 15, 2013. Accessed March 11, 2015.

  • What is an electrocardiogram? National Heart, Lung, and Blood Institute website. Available at: Updated October 1, 2010. Accessed March 11, 2015.

The health information in this Health Library is provided by a third party. TriStar Health does not in any way create the content of this information. It is provided solely for informational purposes. It does not constitute medical advice and is not intended to be a substitute for proper medical care provided by a physician. Always consult with your doctor for appropriate examinations, treatment, testing, and care recommendations. Do not rely on information on this site as a tool for self-diagnosis. If you have a medical emergency, call 911.