Printer Friendly Version Email A Friend Add This Increase Text Size Decrease Text Size




An electrocardiogram (ECG) is a test that records the electrical activity of the heart.

See also:

Alternative Names


How the test is performed

You will be asked to lie down. The health care provider will clean several areas on your arms, legs, and chest, and then attach small patches called electrodes to the areas. It may be necessary to shave or clip some hair so the patches stick to the skin. The number of patches used may vary.

The patches are connected by wires to a machine that turns the heart's electrical signals into wavy lines, which are often printed on paper. The test results are reviewed by the doctor.

You usually need to remain still during the procedure. The health care provider may also ask you to hold your breath for a few seconds as the test is being done. Any movement, including muscle tremors such as shivering, can alter the results. So it is important to be relaxed and relatively warm during an ECG recording.

Sometimes this test is done while you are exercising or under minimal stress to monitor changes in the heart. This type of ECG is often called a stress test.

Electrocardiogram (ECG) - interactive tool
How to prepare for the test

Make sure your health care provider knows about all the medications you are taking, as some can interfere with test results.

Exercising or drinking cold water immediately before an ECG may cause false results.

How the test will feel

An ECG is painless. No electricity is sent through the body. The electrodes may feel cold when first applied. In rare cases, some people may develop a rash or irritation where the patches were placed.

Why the test is performed

An ECG is used to measure:

  • Any damage to the heart
  • How fast your heart is beating and whether it is beating normally
  • The effects of drugs or devices used to control the heart (such as a pacemaker)
  • The size and position of your heart chambers

An ECG is a very useful tool for determining whether a person has heart disease. Your doctor may order this test if you have chest pain or palpitations.

Normal Values
  • Heart rate: 60 to 100 beats per minute
  • Heart rhythm: consistent and even
What abnormal results mean

Abnormal ECG results may be a sign of

Additional conditions under which the test may be performed include the following:

What the risks are

There are no risks. No electricity is sent through the body, so there is no risk of shock.

Special considerations

The accuracy of the ECG depends on the condition being tested. A heart problem may not always show up on the ECG. Some heart conditions never produce any specific ECG changes.

If you have had a heart attack or have heart disease, you may need more than one ECG. Your doctor will tell you when you need the next one.

There is no reason for healthy people to have yearly ECG testing unless they have a family or personal history of specific heart diseases or other medical conditions that affect the heart.


Ganz L, Curtiss E. Electrocardiography. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 52.

ECG Atrioventricular block, ECG tracing High blood pressure tests Electrocardiogram (ECG)
Read More
Exercise stress test
Holter monitor (24h)
Heart disease
Chest pain
Heart palpitations
Dilated cardiomyopathy
Pulse - bounding
Ectopic heartbeat
Stable angina
Heart attack
Anorexia nervosa
Aortic dissection
Aortic insufficiency
Aortic stenosis
Atrial fibrillation/flutter
Atrial septal defect
Cardiac tamponade
Coarctation of the aorta
Delirium tremens
Coronary artery spasm
Digitalis toxicity
Drug-induced lupus erythematosus
Hypokalemic periodic paralysis
Guillain-Barre syndrome
Heart failure
Hypertensive heart disease
Hypertrophic cardiomyopathy
Infectious endocarditis
Sleeping difficulty
Ischemic cardiomyopathy
Lyme disease - early disseminated
Mitral regurgitation - acute
Mitral regurgitation - chronic
Mitral stenosis
Mitral valve prolapse
Multifocal atrial tachycardia
Obstructive sleep apnea
Paroxysmal supraventricular tachycardia (PSVT)
Patent ductus arteriosus
Pericarditis - bacterial
Pericarditis - constrictive
Pericarditis - after heart attack
Peripartum cardiomyopathy
Primary amyloidosis
Hyperaldosteronism - primary and secondary
Primary hyperparathyroidism
Pulmonary hypertension
Pulmonary embolus
Pulmonary valve stenosis
Restrictive cardiomyopathy
Sick sinus syndrome
Systemic lupus erythematosus
Tetralogy of Fallot
Thyrotoxic periodic paralysis
Transient ischemic attack
Transposition of the great vessels
Tricuspid regurgitation
Type 2 diabetes
Unstable angina
Ventricular septal defect
Ventricular tachycardia
Wolff-Parkinson-White syndrome
Related Taxonomy
- Test

Review Date: 5/23/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission ( URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2009 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Home Page
Why Choose Us
Website Terms of Use

Visitor & Patient Info
Patient Portal
We Speak Your Language
Patient Privacy
Contact Us

Find a Physician
Medical Services
Maimonides In the News
Directions & Parking

Medical Education
Career Opportunities
Nurses & Physicians
Staff Intranet Access
Maimonides Medical Center    |    4802 Tenth Avenue    |    Brooklyn, NY 11219    |    718.283.6000    |