Electrocardiogram (ECG)

A test that records the electrical impulses of your heart rhythm.

An electrocardiogram (ECG) records the electrical signals of your heart. It’s a common, non-invasive and painless test used to quickly detect heart problems and monitor the heart’s status in many situations.

During an ECG, sensors (electrodes) are attached to your chest and sometimes to your limbs to detect:

  • Irregularities in your heart rhythm (arrhythmias)
  • If blocked or narrowed arteries in your heart (coronary artery disease) are causing chest pain or a heart attack
  • Structural problems with your heart’s chambers
  • A previous heart attack
  • How well certain ongoing heart disease treatments, such as a pacemaker, are working

You may need a heart rhythm test if you experience any of the following signs and symptoms:

  • Heart palpitations
  • Rapid pulse
  • Chest pain
  • Shortness of breath
  • Dizziness, lightheadedness or confusion
  • Weakness, fatigue or a decline in ability to exercise


No special preparations are necessary for a standard electrocardiogram. Tell your healthcare professional about any medications and supplements you’re taking because some can affect the results of your test.


You may be asked to change into a hospital gown. Then you’ll lie on an examining table or bed. Electrodes will be attached to chest and sometimes to your limbs. The electrodes are sticky patches applied to help record the electrical activity of your heart. Each one has a wire attached to a monitor. If you have hair on the parts of your body where the electrodes will be placed, the technician may shave the hair so that the patches stick.

You can breathe normally during the electrocardiogram. Make sure you’re comfortable and ready to lie still. Moving, talking or shivering may distort the test results. A standard ECG takes a few minutes.

As you lie on the examination table or bed, the electrodes will record the impulses that make your heart beat. The impulses are recorded by a computer and displayed as waves on a monitor or printed on paper.


You can resume your normal activities after your electrocardiogram. Your healthcare professional will look at the waves recorded during your test to see if the impulses are traveling normally. He or she will be able to tell you the results of your ECG the same day it’s performed or at your next appointment.

If your electrocardiogram is normal, you may not need any other tests. If the results show an abnormality with your heart, you may need another ECG or other diagnostic tests, such as an echocardiogram. Treatment depends on what’s causing your signs and symptoms.

Source: Mayoclinic.org