An electrocardiogram (EKG or ECG) is a test
that checks for problems with the electrical activity of your heart. An EKG
heart's electrical activity into line tracings on
paper. The spikes and dips in the line tracings are called waves. See a picture
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. See a picture of the
heart and its electrical system .
Why It Is Done
electrocardiogram (EKG or ECG) is done to:
- Check the heart's electrical activity.
- Find the cause of unexplained chest pain, which could be caused
by a heart attack, inflammation of the sac surrounding the heart (pericarditis), or
- Find the cause of symptoms of
heart disease, such as shortness of breath, dizziness, fainting, or rapid,
irregular heartbeats (palpitations).
- 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
- Check how well mechanical devices that are implanted in the
heart, such as
pacemakers, are working to control a normal
- 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
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 mean. 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
family medicine doctor,
You may receive an EKG as part
of a physical examination at your health professional's office or during a
series of tests at a hospital or clinic. EKG equipment is often portable, so
the test can be done almost anywhere. If you are in the hospital, your heart
may be continuously monitored by an EKG system; this process is called
During an EKG:
- You will lie on a bed or table. Areas on your
arms, legs, and chest where small metal discs (electrodes) will be placed are
cleaned and may be shaved to provide a clean, smooth surface to attach the
electrode discs. A special EKG paste or small pads soaked in alcohol may be
placed between the electrodes and your skin to improve conduction of the
electrical impulses, but in many cases disposable electrodes are used that do
not require paste or alcohol.
- Several electrodes are
attached to the skin on each arm and leg and on your chest. These are hooked to a
machine that traces your heart activity onto a paper. If an older machine is
used, the electrodes may be moved at different times during the test to measure
your heart's electrical activity from different locations on your chest. After
the procedure, the electrode paste is wiped off.
- You will be asked
to lie very still and breathe normally during the test. Sometimes you may be
asked to hold your breath. You should not talk during the test.