Test Overview
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 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
An
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
angina.
- 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
heart.
- Check how well mechanical devices that are implanted in the
heart, such as
pacemakers, 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 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
internist,
family medicine doctor,
electrophysiologist,
cardiologist,
anesthesiologist, or
surgeon.
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
telemetry.
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.
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.
Risks
There is no chance of problems while having an
electrocardiogram (EKG or ECG). An EKG is a completely safe test. In most
cases, there is no reason why you should not be able to get an EKG.
The electrodes are used to transfer an image of the electrical activity
of your heart to tracing on paper. No electricity passes through your body from
the machine, and there is no danger of getting an electrical shock.
Results
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.
The test
usually takes 5 to 10 minutes to complete.
Your doctor will look
at the pattern of spikes and dips on your electrocardiogram 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. See a
picture that explains the
EKG components and intervals.
Electrocardiogram (EKG or ECG) results
| Normal: |
The heart beats in a regular rhythm, usually
between 60 and 100 beats per minute.
|
|
The tracing looks normal.
|
| Abnormal: |
The heart beats too slow (less than 60 beats
per minute).
The heart beats too fast (more than 100 beats per
minute).
The heart rhythm is not regular.
|
|
The tracing does not look
normal.
|
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Not having the electrodes securely attached to
your skin.
- Moving or talking during the
test.
- Exercising before the test.
- Being anxious or
breathing very deeply or rapidly.
What To Think About
- Sometimes your EKG may look normal even when
you have heart disease. For this reason, the EKG should always be interpreted
along with your symptoms, past health, physical examination, and, if necessary,
other test results.
- An electrocardiogram cannot predict whether you
will have a
heart attack.
- At first, an EKG done
during a heart attack may look normal or unchanged from a previous EKG. So the
EKG may be repeated over several hours and days (called serial EKGs) to look
for changes.
- There are several other types of electrocardiograms,
including telemetry, ambulatory monitoring (using a Holter monitor or event
monitor), and exercise EKG testing. For more information, see the topics
Ambulatory Electrocardiogram and
Exercise Electrocardiogram.
- Sometimes EKG
abnormalities can be seen only during exercise or while symptoms are present.
To check for these changes in the heartbeat, an ambulatory EKG or stress EKG
may be done.
- An ambulatory EKG is a type of portable,
continuous EKG monitor. For more information, see the topic
Ambulatory Electrocardiogram.
- A stress EKG
is a type of EKG done during exercise. A resting EKG is always done before an
exercise EKG test, and results of the resting EKG are compared to the results
of the exercise EKG. A resting EKG may also show a heart problem that would
make an exercise EKG unsafe. For more information, see the topic
Exercise Electrocardiogram.
- Some doctors think that people older than age 35
need a baseline EKG before problems develop. This baseline EKG may be compared
to later EKGs to see if changes have occurred. But a baseline EKG is expensive
and may not be covered by insurance. Baseline EKGs may be most useful in people
who have other conditions or diseases that increase their chances of having
heart disease.
- Sometimes doctors automatically schedule routine tests because they think that's what patients expect. But experts say routine heart tests can be a waste of time and money. For more information, see Heart Tests: When Do You Need Them?
Other Places To Get Help
Organizations
|
American Heart Association (AHA)
|
| 7272 Greenville Avenue |
| Dallas, TX 75231 |
| Phone: |
1-800-AHA-USA1 (1-800-242-8721) |
| Web Address: |
www.heart.org |
| |
|
Visit the American Heart Association (AHA) website for information on
physical activity, diet, and various heart-related conditions. You can search for information on heart disease and stroke, share information with friends and family, and use tools to help you make heart-healthy goals and plans. Contact the AHA to find your
nearest local or state AHA group. The AHA provides brochures and information
about support groups and community programs, including Mended Hearts, a
nationwide organization whose members visit people with heart problems and
provide information and support.
|
|
|
Heart Rhythm Society
|
| 1400 K Street NW |
| Suite 500 |
| Washington, DC 20005 |
| Phone: |
(202) 464-3400 |
| Fax: |
(202) 464-3401 |
| Web Address: |
www.hrsonline.org |
| |
|
The Heart Rhythm Society provides information for
patients and the public about heart rhythm problems. The website includes a
section that focuses on patient information. This information includes causes,
prevention, tests, treatment, and patient stories about heart rhythm problems.
You can use the Find a Specialist section of the website to search for a heart
rhythm specialist practicing in your area.
|
|
|
National Heart, Lung, and Blood Institute
(NHLBI)
|
| P.O. Box 30105 |
| Bethesda, MD 20824-0105 |
| Phone: |
(301) 592-8573 |
| Fax: |
(240) 629-3246 |
| TDD: |
(240) 629-3255 |
| Email: |
nhlbiinfo@nhlbi.nih.gov |
| Web Address: |
www.nhlbi.nih.gov |
| |
|
The U.S. National Heart, Lung, and Blood Institute
(NHLBI) information center offers information and publications about preventing
and treating:
- Diseases affecting the heart and circulation, such as heart
attacks, high cholesterol, high blood pressure, peripheral artery disease, and
heart problems present at birth (congenital heart diseases).
- Diseases that affect the lungs, such as asthma, chronic
obstructive pulmonary disease (COPD), emphysema, sleep apnea, and
pneumonia.
- Diseases that affect the blood, such as anemia,
hemochromatosis, hemophilia, thalassemia, and von Willebrand disease.
|
|
References
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
- U.S. Preventive Services Task Force (2004). Screening for coronary heart disease: Recommendation statement. Annals of Internal Medicine, 140(7): 569–572. Also available online: http://www.ahrq.gov/clinic/3rduspstf/chd/chdrs.htm.
Credits
|
By
|
Healthwise Staff |
|
Primary Medical Reviewer
|
E. Gregory Thompson, MD - Internal Medicine |
|
Specialist Medical Reviewer
|
Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology |
|
Last Revised
|
March 18, 2010 |