How Doctors Diagnose Arrhythmia

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 .

• 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, history, 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. Therefore, 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 medical tests 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 medical test 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 medical test 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.