An electrocardiogram (ECG or EKG) is a test that records the electrical activity of your heart.

Your heart has an electrical system that makes sure it contracts (squeezes) in an orderly way.

Certain heart conditions, such as arrhythmias, are caused by problems with the heart’s electrical conduction system. An ECG is often the first tool used to detect such problems.

An ECG is used to measure:

  • Any damage to the heart
  • How fast your heart is beating and whether it is beating normally
  • The effects of drugs or devices used to control the heart (such as a pacemaker)
  • The size and position of your heart chamber

An ECG may be ordered if:

  • You have chest pain or palpitations
  • You are scheduled for surgery
  • You have had heart problems in the past
  • You have a strong history of heart disease in the family

What to Expect for Your ECG

You will be asked to lie down. Your health care provider will attach small patches called electrodes to several areas including your arms, legs and chest. The patches are then connected by wires to a machine that turns the heart’s electrical signals into results that can be printed on paper.

You will need to remain still during the procedure. The provider may ask you to hold your breath for a few seconds as the test is being done.

Sometimes this test is done while you are exercising or under light stress to look for changes in the heart. This type of ECG is often called a stress test.

An ECG is painless. No electricity is sent through your body. The electrodes may feel cold when first applied.