Key Points

• An electrocardiogram (EKG) is a test that detects and records the electrical activity of the heart.
• EKGs are used to evaluate signs and symptoms that could indicate heart problems.
• Many heart problems change the electrical “signature” of the heart in distinct ways. EKG recordings of this electrical signature can help reveal these heart problems.
• During an EKG, electrical signals in the heart are detected by electrodes placed on the skin. A machine records them on graph paper or displays them on a screen.
• An EKG is painless and harmless, and usually takes about 10 minutes to complete.
• Special EKG tests are done to detect certain kinds of heart symptoms, such as those that are present for only a few minutes out of the day, or that happen only while a person is exercising.