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What is an electrocardiogram (ECG)?
An electrocardiogram (ECG) is a simple and painless procedure that measures the electrical activity of the heart. Every time the heart beats, an electrical signal circulates through it. An electrocardiogram shows if your heart is beating at a rhythm and with a normal force. It also shows the size and position of the heart chambers. An abnormal electrocardiogram can be a sign of damage or heart disease.

Alternative names: EKG

For what do you use it?
The electrocardiogram is used to find and monitor various heart diseases, for example:

Irregular heartbeat (arrhythmia)
Artery obstruction
Heart damage
Heart failure
Heart attack: Electrocardiograms are used in ambulances, emergency rooms and hospitals to diagnose a heart attack
Sometimes an electrocardiogram is included in a routine examination of middle-aged or older adults because the risk of heart disease increases with age.

Why can I need an electrocardiogram?
You may need an electrocardiogram if you have symptoms of heart disease, such as:

Chest pain
Fast heartbeat
Arrhythmia (you may feel that your heart has skipped a beat or is fluttering)
Difficulty breathing
You may also need this test if:

Have had a heart attack or other heart problem
Have a family history of heart disease
You have surgery scheduled. Your healthcare provider may want to check your heart before the procedure.
It has a pacemaker. The electrocardiogram can show if the device is working
You are taking medicine for heart disease. The electrocardiogram can show if your medication is effective or if you need changes in your treatment
What happens during an electrocardiogram?
The electrocardiogram can be done in a doctor’s office, an outpatient clinic or a hospital. During the procedure:

You lie on a stretcher
The health professional places several electrodes (small sensors that adhere to the skin) on the arms, legs and chest. Before doing this, you may have to shave or trim excess hair
The electrodes are connected with wires to a computer that records the electrical activity of the heart
The activity is displayed on the computer monitor and printed on paper.
The procedure only lasts about three minutes.
Should I do something to prepare for the test?
An electrocardiogram does not require any special preparations.

Does this test have any risk?
The risks of an electrocardiogram are minimal. You may feel a slight discomfort or irritation on the skin after the electrodes are removed. There is no risk of electric shock. The electrocardiogram does not send any electricity to the body. Just register the electricity.

What do the results mean?
Your healthcare provider will check your electrocardiogram to see if the rhythm and heart rate are constant. If your results are not normal, you may have:

A too fast or slow heartbeat
Insufficient blood supply to the heart
A dilation in a wall of the heart. This is known as aneurysm.
Thickening of the heart walls
Heart attack (results may indicate if you had a heart attack before or if you are having one during the electrocardiogram)
If you have questions about your results, check with your doctor or healthcare professional.

The word electrocardiogram has two abbreviations ECG or EKG. Both are correct and commonly used. EKG is based on the German spelling, «elektrokardiogramm». ECG should not be confused with EEG, a test that measures brain waves.

Show References
Related Health Issues
Heart attack
Heart disease
Heart failure
Pacemaker and implantable defibrillator
Related Laboratory Tests
How to understand the result of your laboratory tests
Stress tests
The medical information provided is for informational purposes only and not to be used as a substitute for medical advice, diagnosis or professional treatment. Please contact your health care provider if you have questions about medical conditions or for the interpretation of test results.