An electrocardiogram (EKG or ECG) is a test that checks for problems with the electrical activity of your heart. An EKG shows the heart's electrical activity as line tracings on paper. The spikes and dips in the tracings are called waves.
The heart is a muscular pump made up of four chambers. The two upper chambers are called atria. The two lower chambers are called ventricles. A natural electrical system causes the heart muscle to contract. This pumps blood through the heart to the lungs and the rest of the body.
Why It Is Done
An EKG is done to:
- Check the heart's electrical activity.
- Find the cause of unexplained chest pain or pressure. This could be caused by a heart attack, inflammation of the sac surrounding the heart (pericarditis), or angina.
- Find the cause of symptoms of heart disease. Symptoms include shortness of breath, dizziness, fainting, and heartbeats that are rapid and irregular (palpitations).
- Find out if the walls of the heart chambers are too thick.
- Check how well medicines are working and see if they are causing side effects that affect the heart.
- Check how well mechanical devices that are implanted in the heart, such as pacemakers, are working. These devices help to control the heartbeat.
- Check the health of the heart when other diseases or conditions are present. These include high blood pressure, high cholesterol, cigarette smoking, diabetes, and a family history of early heart disease.
How To Prepare
- Understand exactly what test is planned, along with the risks, benefits, and other options.
- Tell your doctor ALL the medicines, vitamins, supplements, and herbal remedies you take. Some may increase the risk of problems during your test. Your doctor will tell you if you should stop taking any of them before the test and how soon to do it.
How It Is Done
- You may have to remove certain jewelry.
- You will take your top off and be given a gown to wear.
- You will lie on a bed or table. Parts of your arms, legs, and chest will be cleaned and may be shaved.
- Small pads or patches (electrodes) will be placed, like stickers, on your skin on each arm and leg and on your chest. The electrodes are hooked to a machine that traces your heart activity onto a paper.
- During the test, lie very still and breathe normally. Do not talk during the test.
How long the test takes
The test usually takes 5 to 10 minutes.
How It Feels
The electrodes may feel cool when they are put on your chest. If you have a lot of hair on your chest, a small area may need to be shaved to put the electrodes on. When the electrodes are taken off, they may pull your skin a little.
An EKG is a completely safe test. No electricity passes through your body from the machine, and there is no danger of getting an electrical shock.
The doctor will look at the pattern of spikes and dips on your EKG to check the electrical activity in different parts of your heart. The spikes and dips are grouped into different sections that show how your heart is working.
The heart beats in a regular rhythm, usually between 60 and 100 beats per minute.
The tracing looks normal.
The heart beats too slowly (such as less than 60 beats per minute).
The heart beats too fast (such as more than 100 beats per minute).
The heart rhythm is not regular.
The tracing does not look normal.
Sometimes your EKG may look normal even when you have heart disease. For this reason, the EKG should always be looked at along with your symptoms, past health, and a physical exam.
Current as of: January 10, 2022
Author: Healthwise Staff
Rakesh K. Pai MD, FACC - Cardiology, Electrophysiology
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
George Philippides MD - Cardiology