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Electrocardiogram

  1. What is an electrocardiogram?
  2. Reasons for needing an electrocardiogram
  3. Types of ECG
  4. How is an electrocardiogram carried out?
  5. ECG results
  6. Risks

What is an electrocardiogram?

An electrocardiogram, also known as an ECG or EKG, is a simple, painless procedure used to test and record the heart’s rhythm and electrical activity. During the procedure, small electrodes are attached to the skin, through which the heart’s electrical pulses can be monitored.

An electrocardiogram can be ordered by a heart specialist, also called a cardiologist, or a normal doctor to check for a variety of heart conditions, including heart attacks and arrhythmia, an irregular heartbeat. The procedure may be carried out at a doctor’s office or hospital and comes with no serious risks.[1]

Reasons for needing an electrocardiogram

An electrocardiogram is typically used in conjunction with other tests in order to diagnose or monitor various heart conditions.

People experiencing chest pain (angina), heart palpitations, shortness of breath or other symptoms may be given an electrocardiogram in order to investigate the underlying causes of the problems.

The procedure is able to detect conditions including:[2]

  • Atrial fibrillation: A condition that often causes irregular heartbeats
  • Tachycardia: When the heart beats faster than normal, especially while resting
  • Heart attacks (myocardial infarction): When the tissue of the heart muscle starts to die due to a sudden, significant reduction in the supply of oxygen-rich blood, most often caused by coronary heart disease.[3][4] Read more about heart attacks
  • Coronary heart disease: When the flow of blood to the heart is blocked by a buildup of plaque, a waxy material made up of fats, cholesterol, calcium and other substances, inside the blood vessels.[2][5] Read more about coronary heart disease
  • Cardiomyopathy: A thickening or enlargement of the walls of the heart

An electrocardiogram may also be used to monitor the progress of a certain condition or to see how medication is affecting the heart.

A normal reading from an electrocardiogram does not completely rule out heart problems, as conditions that come and go may not be detected by the test.[6] To overcome this problem, a portable ECG machine, called a Holter monitor, may be used. This device is worn continuously over 24 or 48 hours in order to monitor the heart as a person goes about their daily life.[7]

Types of electrocardiogram

There are three main types of electrocardiogram, of which one is selected depending on what kind of condition is being diagnosed or monitored.[2]

  • Rest ECG: The most common type, carried out while the testee is lying down in a horizontal position
  • Exercise or stress ECG: Carried out while the testee is using a treadmill or exercise bike
  • Ambulatory ECG: A portable machine is used, allowing the test to be performed from home

How is an electrocardiogram carried out?

An electrocardiogram will usually be carried out in a hospital or doctor’s office. First, the testee will be asked to change into a hospital gown or to remove the clothes on their torso. Next, they will be asked to lie down on their back on a hospital bed.

Electrodes, usually 10 or 12, will be fixed to the torso and sometimes to the limbs. The electrodes are relatively small, sticky and attached to the electrocardiogram machine through wires. To secure the electrodes, hair on certain parts of the body may be shaved.

During the test – which will usually only takes a few minutes – the testee will be asked to breathe normally and avoid excessive movement or talking, as this may distort the results. The electrodes will monitor the electrical pulses of the heart, which are then recorded and printed as waves on a piece of paper.[8]

The procedure will be slightly different in the case of an exercise or ambulatory ECG.

Electrocardiogram results

The results from an electrocardiogram will generally be displayed electronically or printed on paper. After they have been compiled, the results will typically be analyzed by a doctor or specialist before being shared. This may happen on the same day, or a person may be required to return to the hospital or doctor’s office at a later date.

Results from a healthy patient will usually show a consistent rhythm from the heart and a heart rate of between 60 and 100 beats per minute.[9]

Risks associated with an electrocardiogram

An electrocardiogram is a very safe and painless procedure which is considered routine by healthcare providers. There is a slight risk of pain when the electrodes are removed and of a mild rash in the areas where they were applied.[2]


  1. National Heart, Lung, and Blood Institute. “Electrocardiogram.” December 9, 2016. Accessed August 24, 2017.

  2. NHS Choices. “Electrocardiogram (ECG).” July 21, 2015. Accessed August 24, 2017.

  3. Heart Foundation. “What is coronary heart disease?” Accessed February 23, 2018.

  4. National Heart, Lung and Blood Institute. “Heart Attack.” Accessed February 23, 2018.

  5. American Heart Association. “Atherosclerosis.” November 16, 2017. Accessed February 24, 2018.

  6. Patient. “Electrocardiogram.” July 14, 2017. Accessed August 24, 2017.

  7. American Heart Association. “Holter Monitor.” June 5, 2017. Accessed August 24, 2017.

  8. Mayo Clinic. “Electrocardiogram (ECG) - What you can expect.” February 2, 2017. Accessed August 24, 2017.

  9. MedlinePlus. “Electrocardiogram.” May 5, 2016. Accessed August 24, 2017.