Health Library

Electrocardiogram

Definition

An ECG can show the electrical activity of your heart. It will appear as a pattern on a graph. It can help to show abnormal movements or working of the heart.

ECG Waves
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Reasons for Test

An ECG 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 lead to your doctor ordering an ECG include:

  • Chest discomfort or pain
  • Shortness of breath
  • Rapid heart beat
  • Weakness
  • Nausea
  • History of fainting

An ECG may also be done 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 problems linked to this test.

What to Expect

Prior to Test

You may:

  • Be asked about your health history.
  • Your chest may be shaved.

Description of Test

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

After Test

You can return to your normal activity after the test.

How Long Will It Take?

3-4 minutes

Will It Hurt?

No

Results

Your doctor will review the ECG. The results may lead to:

  • Diagnosis
  • More tests to confirm a diagnosis
  • Treatment plan

Call Your Doctor

Call your doctor if you have heart-related symptoms. This includes chest pain or trouble breathing.

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

Resources

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

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

Canadian Resources

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

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

References

Electrocardiogram (EKG or ECG). American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Electrocardiogram-ECG-or-EKG%5FUCM%5F309050%5FArticle.jsp. Updated September 11, 2015. Accessed March 5, 2018.

Noninvasive tests and procedures. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Non-Invasive-Tests-and-Procedures%5FUCM%5F303930%5FArticle.jsp. Updated September 16, 2016. Accessed March 5, 2018.

What is an electrocardiogram? National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/ekg/. Accessed March 5, 2018.