An electrocardiogram (ECG) measures the heart's electrical activity to help evaluate its function and identify any problems that might exist. The ECG can help determine the rate and regularity of heartbeats, the size and position of the heart's chambers, and whether there is any damage present.
There is nothing painful about getting an ECG. The patient is asked to lie down, and a series of small metal tabs (called electrodes) are fixed to the skin with sticky papers. These electrodes are placed in a standard pattern on the shoulders, the chest, the wrists, and the ankles. After the electrodes are in place, the person is asked to hold still and, perhaps, to hold his or her breath briefly while the heartbeats are recorded for a short period. The patient also might be asked to get up and exercise for a while.
The information is interpreted by a machine and drawn as a graph. The graph consists of multiple waves, which reflect the activity of the heart. The height, length, and frequency of the waves are read in the following way:
A person's heartbeat should be consistent and even. ECGs look for abnormally slow and fast heart rates, abnormal rhythm patterns, conduction blocks (short-circuits of the heart's electrical impulses that cause rhythm inconsistencies between the upper and lower chambers) — and four types of heart damage:
Computerized ECGs can be combined with other tests to provide a multimedia account of the heart. These additional tests include echocardiograms (which are basically "ultrasound" tests that bounce sound off the heart and use the echoes to produce an image) and thallium scans (which are kind of like X-rays and use a radioactive tracer, injected into the bloodstream, to help draw a picture of the heart).
In the past, the ECG was recorded on a machine that drew on long strips of paper, with records from each electrode presented in a standard sequence. Now the ECG tracings are stored as computer files that can be called up and printed.
Results of the ECG are available immediately. In fact, the ECG machine's computer even provides an instant interpretation of the findings as it makes the report. However, the doctor also might ask an expert, usually a cardiologist, to help analyze and interpret the ECG.
Reference ranges for heart rate and the relative lengths and sizes of the various components of the heartbeat figures vary, and diagnostic differences may be subtle, requiring an expert eye to detect them.
Reviewed by: Steven Dowshen, MD
Date reviewed: October 2013
|National Heart, Lung, and Blood Institute (NHLBI) The NHLBI provides the public with educational resources relating to the treatment of heart, blood vessel, lung, and blood diseases as well as sleep disorders.|
|American Heart Association This group is dedicated to providing education and information on fighting heart disease and stroke. Contact the American Heart Association at: American Heart Association|
7272 Greenville Ave.
Dallas, TX 75231
|A Directory of Medical Tests Sometimes, doctors need to order tests to evaluate a child's health or to understand what's causing an illness. Here are some common ones.|
|Ventricular Septal Defect Ventricular septal defect, or VSD, is a heart condition that a few teens can have. Find out what it is, how it happens, and what doctors do to correct it.|
|Heart and Circulatory System The heart and circulatory system (also called the cardiovascular system) make up the network that delivers blood to the body's tissues.|
|If Your Child Has a Heart Defect Congenital heart defects are relatively common, affecting almost 1 in every 100 newborns in the United States.|
|Heart Murmurs and Your Child A heart murmur diagnosis is extremely common. Most murmurs are not a cause for concern and do not affect a child's health.|
|Heart Murmurs Everyone's heart makes sounds, but some people have hearts that make more noise than others. Usually, however, these heart murmurs don't mean anything is wrong. Find out more about these mysterious murmurs.|
|EKG (Video) This video shows what it's like to have an electrocardiogram (EKG for short).|
|Getting an EKG (Video) Getting an EKG doesn't hurt and it gives doctors important info about how your heart is beating. Watch what happens in this video for kids.|
|Your Heart & Circulatory System Your heart is a hard-working muscle. Find out more in this article for kids.|
|Arrhythmias Arrhythmias are abnormal heart rhythms usually caused by an electrical "short circuit" in the heart. Many don't require treatment; however, some need to be evaluated and treated by a doctor.|
|Congenital Heart Defects Congenital heart defects involve abnormal or incomplete development of the heart. Learn about the different types of congenital heart defects.|
What to expect when coming to Akron Children's
For healthcare providers and nurses
Residency & Fellowships, Medical Students, Nursing and Allied Health
For prospective employees and career-seekers
Our online community that provides inspirational stories and helpful information.