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Electrocardiogram

An electrocardiogram (EKG or ECG) is a test that checks for problems with the electrical activity of your heart. An EKG translates the heart's electrical activity into line tracings on paper. The spikes and dips in the line tracings are called waves. See an illustration of the EKG components and intervals.
The heart is a muscular pump made up of four chambers. The two upper chambers are called atria, and the two lower chambers are called ventricles. A natural electrical system causes the heart muscle to contract and pump blood through the heart to the lungs and the rest of the body.

Why It Is Done

An electrocardiogram (EKG or ECG) is done to:
Find the cause of unexplained chest pain, such as a heart attack, inflammation of the sac surrounding the heart (pericarditis), or reduced blood flow to the heart muscle (ischemia).
Find the cause of symptoms of heart disease, such as unexplained chest pain, shortness of breath, dizziness, fainting, or rapid, irregular heartbeats (palpitations).
Check the heart's electrical activity.
Find out if the walls of the heart chambers are too thick (hypertrophied).
Check how well medicines are working and whether they are causing side effects that affect the heart.
Check how well mechanical devices, such as pacemakers or defibrillators implanted in the heart, are working to control a normal heartbeat.
Check the health of the heart when other diseases or conditions are present, such as high blood pressure, high cholesterol, cigarette smoking, diabetes, or a family history of early heart disease.
How To Prepare

Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take. If you take heart medicines, your doctor will tell you how to take your medicines before you have this test.
Remove all jewelry from your neck, arms, and wrists. Men are usually bare-chested during the test. Women may often wear a bra, T-shirt, or gown. If you are wearing stockings, you should take them off. You will be given a cloth or paper covering to use during the test.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will indicate. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

An electrocardiogram (EKG or ECG) is usually done by a health professional, and the resulting EKG is interpreted by a doctor, such as an internist, family medicine doctor, electrophysiologist, cardiologist, anesthesiologist, or surgeon.