Electrocardiogram (EKG or ECG)

What is it?

An electrocardiogram (ECG or EKG) is a routine test that is used to look at the electrical activity of the heartbeat and check for any problems. Small metal disks called electrodes are placed on the skin. The electrodes are used to pick up the electrical impulses of the heart. The impulses are recorded onto line tracings on a paper, giving doctors a record of your heart's electrical activity.

How does it work?

For your heart to beat, an electrical impulse is sent from the sinoatrial (SA) node, which is located in the heart. The SA node helps the heart keep a steady pace. An electrocardiogram can trace the path of electrical energy that is sent from the SA node and through the heart, letting a doctor know if there is a problem that might cause the heart to beat irregularly.

Reasons for an Electrocardiogram

An electrocardiogram can tell a doctor a lot about the heart and how it is working. It provides information about heart rhythm, the size and function of the chambers of the heart, and the heart muscle. A healthy person's electrocardiogram has a certain pattern. When there are changes in that pattern, a doctor can tell that there is a problem with your heart. An EKG is done to detect:

  • Heart’s electrical activity
  • Check the health of the heart
  • Possible causes of unexplained chest pain (angina)
  • Cause of symptoms of a heart attack
  • If the walls of the heart chambers are too thick (hypertrophied)
  • How well medicines are working and if they have an effect on the heart
  • How well pacemakers are working to control a normal heartbeat

What to expect

During the test, the patient will lie on an examination table or bed. A technician will clean, and possibly shave, the areas on the body where the small metal discs (electrodes) will be placed, usually the chest, arms, and legs. The electrodes have wires called leads, which hook up to the electrocardiogram machine.

Once the electrodes are in place, the patient will be asked to lie down. The technician will enter some information into the electrocardiogram machine and then ask the patient to lie still and breathe normally for about a minute while the machine takes its readings. The test is completely safe and painless and no special preparation is needed before having an electrocardiogram.

St. Luke's Heart & Vascular