Electrocardiogram (ECG)

An electrocardiogram (ECG) is a test that shows and records the electrical activity of the heart during a period of time. It checks how fast your heart is beating (your heart rate), if the heart is beating normally (the rhythm) and how well the heart muscle is working.

An electrocardiogram may also be called an EKG.

Why an ECG is done

An ECG may be done to:

  • check for heart problems and heart disease
  • measure any heart damage
  • check the health of your heart before surgery or other treatments
  • monitor the effects of cancer treatments on your heart
  • provide a baseline to compare with future ECGs

How an ECG is done

An ECG is done in a hospital, medical clinic or doctor’s office. It usually takes 5to10 minutes.

You will be asked to remove your clothes from the top half of your body and then lie on an exam table.

Special sensors called electrodes are placed like stickers on the skin of your chest, arms and legs. In some cases, the hair on those areas needs to be shaved or clipped so that the electrodes can stick properly. The electrodes are attached to wires that connect to an ECG machine.

The ECG machine takes the information and makes a graph with wavy lines called an electrocardiograph. After the test is done, the electrodes are removed.

Side effects

An ECG is a painless test and doesn’t usually cause any side effects. Some people may develop a slight rash or irritation where the electrodes were attached to the skin. This usually goes away on its own.

An ECG does not pass electricity to the body so you don’t need to worry about getting electric shocks.

Getting your results

Your doctor will review your ECG results from the electrocardiograph. This can include:

  • comparing how fast your heart is beating to a normal range
  • checking for an irregular heartbeat
  • looking for abnormalities in the heart muscle or the flow of blood to and from the heart

Your doctor may recommend more tests, procedures, follow-up care or treatment.

Special considerations for children

Preparing children before a test or procedure can help lower their anxiety, increase their cooperation and develop their coping skills. This includes explaining to children what will happen during the test, such as what they will see, feel and hear. It is important to let children know that an ECG does not hurt and they won’t get any electric shocks.

Preparing a child for an ECG depends on the age and experience of the child. Find out more about helping your child cope with tests and treatments.

Expert review and references

Medical disclaimer

The information that the Canadian Cancer Society provides does not replace your relationship with your doctor. The information is for your general use, so be sure to talk to a qualified healthcare professional before making medical decisions or if you have questions about your health.

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