Thumbnail image of: Nodes Responsible for Cardiac Rhythm: Illustration

Electrocardiogram (ECG or EKG)

What is an electrocardiogram (ECG or EKG)?

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

An electrical signal in your heart starts each heartbeat, causing the heart muscle to squeeze (contract). Normally, this signal starts in the upper right chamber of the heart (the right atrium) at a place called the sinus node. The signal then follows normal pathways to the upper left atrium and to the lower chambers of the heart (the ventricles). These electrical signals can be detected through wires placed on the skin. The ECG records these electrical signals.

When is it used?

Your healthcare provider can diagnose heart problems and other conditions by looking at the pattern made by the electric signal. An ECG, often done along with other tests, can show:

  • How fast the heart is beating
  • Abnormal heartbeats and heart rhythms
  • The strength of the electrical signals and how long they take to go through the heart muscle
  • Thickening of the heart muscle caused by high blood pressure or other diseases
  • Signs of heart attack or heart failure
  • Heart problems you were born with, such as abnormal heart valves or holes in the heart
  • Parts of the heart that are not getting enough blood
  • High levels of potassium or other chemicals that affect your heartbeat

How do I prepare for this test?

  • You may need to avoid taking certain medicines before the test because they might affect the test result. Make sure your healthcare provider knows about any medicines, herbs, or supplements that you are taking. Ask your provider before stopping any of your regular medicines.
  • Follow any instructions your healthcare provider gives you.
  • Ask any questions you have before the procedure. You should understand what your healthcare provider is going to do. You have the right to make decisions about your healthcare and to give permission for any tests or procedures.

What happens during the test?

An ECG is a painless test that takes less than 5 minutes. It can be done in your healthcare provider’s office, clinic, or hospital. Small sticky pads are put on your chest, arms, and legs. Long wires will be attached to the pads and connected to a recording machine.. You need to lie still and not talk while the test is being done.

What happens after the test?

After the test, you can go home and go back to your normal activities. Any skin irritation from the pads will go away quickly after they are removed.

Ask your healthcare provider:

  • How and when you will hear your test results
  • What symptoms or problems you should watch for and what to do if you have them

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.

What are the risks of this test?

There is no risk from this test.

Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2015-02-03
Last reviewed: 2015-01-20
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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