URL of this page: https://medlineplus.gov/lab-tests/electrocardiogram/


What is an electrocardiogram (EKG) test?

An electrocardiogram (EKG) test is a simple, painless procedure that measures electrical signals in your heart. Each time your heart beats, an electrical signal travels through the heart. An EKG can show if your heart is beating at a normal rate and strength. It also helps show the size and position of your heart's chambers. An abnormal EKG can be a sign of heart disease or damage.

Other names: ECG test

What is it used for?

An EKG test is used to find and/or monitor various heart disorders. These include:

  • Irregular heartbeat (known as arrhythmia)
  • Blocked arteries
  • Heart damage
  • Heart failure
  • Heart attack. EKGs are often used in the ambulance, emergency room, or other hospital room to diagnose a suspected heart attack.

An EKG test is sometimes included in a routine exam for middle-aged and older adults, as they have a higher risk of heart disease than younger people.

Why do I need an EKG test?

You may need an EKG test if you have symptoms of a heart disorder. These include:

You may also need this test if you:

  • Have had a heart attack or other heart problems in the past
  • Have a family history of heart disease
  • Are scheduled for surgery. Your health care provider may want to check your heart health before the procedure.
  • Have a pacemaker. The EKG can show how well the device is working.
  • Are taking medicine for heart disease. The EKG can show if your medicine is effective, or if you need to make changes in your treatment.

What happens during an EKG test?

An EKG test may be done in a provider's office, outpatient clinic, or a hospital. During the procedure:

  • You will lie on an exam table.
  • A health care provider will place several electrodes (small sensors that stick to the skin) on your arms, legs, and chest. The provider may need to shave or trim excess hair before placing the electrodes.
  • The electrodes are attached by wires to a computer that records your heart's electrical activity.
  • The activity will be displayed on the computer's monitor and/or printed out on paper.
  • The procedure only takes about three minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for an EKG test.

Are there any risks to the test?

There is very little risk to having an EKG. You may feel a little discomfort or skin irritation after the electrodes are removed. There is no risk of electric shock. The EKG doesn't send any electricity to your body. It only records electricity.

What do the results mean?

Your health care provider will check your EKG results for a consistent heartbeat and rhythm. If your results were not normal, it may mean you have one of the following disorders:

  • Arrhythmia
  • A heartbeat that is too fast or too slow
  • Inadequate blood supply to the heart
  • A bulge in the heart's walls. This bulge is known as an aneurysm.
  • Thickening of the heart's walls
  • A heart attack (Results can show if you've had a heart attack in the past or if you are having an attack during the EKG.)

If you have questions about your results, talk to your health care provider.


An electrocardiogram may be called an EKG or an ECG. Both are correct and commonly used. EKG is based on the German spelling, elektrokardiogramm. EKG may be preferred over ECG to avoid confusion with an EEG, a test that measures brain waves.


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The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.