The electrocardiogram (ECG or EKG) is a test used to evaluate the rhythm and electrical activity of the heart. A stress test is an ECG that is recorded while you exercise.
An ECG is used to diagnose
heart attacks
and rhythm abnormalities. It can also provide clues about other heart and lung conditions and medical conditions not primarily related to heart.
Heart problems can cause a variety of symptoms. Other conditions that can alter the body’s balance of electrolytes (especially potassium and magnesium) can also cause symptoms and changes in the ECG. An ECG is also used to detect problems that are not primarily related to the heart, such as overdoses of certain drugs. Symptoms that may prompt an ECG include the following:
An ECG is also typically obtained from people who:
Are about to have surgery with general anesthesia for purposes of detecting heart conditions that could worsen under the stresses of certain procedures and put a patient at risk for complications.
Are in occupations that stress the heart, or where public safety is a concern
Are over age 40, as a routine baseline
Already have heart disease, particularly to periodically monitor your status and to check your reaction to new medication
Risk Factors for Complications During the Procedure
The actual process of obtaining an ECG carries no risk of complications. In addition, the test is painless. When an ECG is obtained while you exercise, the only risk is related to the exercise, not the performance of the ECG. During exercise, the ECG serves to monitor your heart function and capture warning signals of heart trouble. In certain cases, an ECG may be normal even though heart disease is present.
What to Expect
Prior to Procedure
You will have a physical exam and be asked about your medical history.
If you have a very hairy chest, several patches of chest hair may need to be shaved.
For an exercise ECG (stress test):
Allow two hours between your last meal and the stress test.
Wear comfortable clothing and walking shoes.
During Procedure
You’ll be asked to lie quietly on your back, with your shirt off. Six small adhesive pads or suction cups with attached wires will be placed across your chest. Others will be placed on your arms and legs. The wires will connect to the ECG machine.
If you’re having a stress test, your ECG will be recorded while you exercise, usually on a treadmill or bicycle. For treadmills, the speed and slope will be gradually increased as you walk. The test will continue until you have reached a certain heart rate, certain ECG changes occur, or you are too tired to continue, are short of breath, or have chest pain.
Anesthesia
None
Description of the Procedure
When your heart beats, it generates electrical signals. The ECG detects these signals from the surface of your skin and records them on a piece of graph paper. You will not feel anything during the procedure.
After Procedure
Depending on your condition and your doctor’s assessment, you may be required to have additional tests. If you have a heart condition or abnormal ECG, keep a recent copy of your ECG in your wallet, purse, or car.
How Long Will It Take?
A resting ECG takes approximately 3-4 minutes. An exercise ECG will take longer since it includes several minutes to up to a half hour of exercise (depending on what you can tolerate), as well as some monitoring after exercise.
Will It Hurt?
No
Possible Complications
There are no complications for a resting ECG. Complications of an exercise ECG would be related to exercise and your heart’s response to the exercise.
Average Hospital Stay
Hospitalization is usually not required, unless symptoms are potentially serious and additional tests, treatment, or surgery are needed.
Postprocedure Care
You may resume activities as recommended by your doctor.
Outcome
Your doctor will interpret the ECG. Based on the results and additional information about your health, he or she may make recommendations for treatment during a follow-up appointment.
Call Your Doctor If Any of the Following Occurs
Worsening of your heart-related symptoms
RESOURCES:
American Heart Association http://www.americanheart.org
American Medical Association http://www.ama-assn.org
CANADIAN RESOURCES:
Heart and Stroke Foundation of Canada http://ww2.heartandstroke.ca/Page.asp?PageID=24
University of Ottawa Heart Institute http://www.ottawaheart.ca/UOHI/Welcome.do
References:
Diagnostic tests: electrocardiogram. The Harvard Medical School Family Health Guide website. Available at: http://www.health.harvard.edu. Accessed on January 8, 2003.
Electrocardiogram. Emedicine website. Available at: http://www.emedicine.com. Accessed on January 8, 2003.
Electrocardiogram. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/electrocardiogram/HB00014.
Accessed on November 15, 2006.
Electrocardiogram. University of Michigan website. Available at: http://www.med.umich.edu/1libr/aha/aha_elecgram_car.htm. Accessed on Novemeber 15, 2006.
Electrocardiogram. University of Michigan website. Available at:
http://www.med.umich.edu/1libr/tests/teste13.htm.
Accessed on January 8, 2003.
Harrison’s Principles of Internal Medicine. 16 ed. McGraw-Hill Professional; 2004.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
