Electrocardiography is a testing method commonly used to determine if the heart has been damaged.
An electrocardiogram is a graphic record of the heart's electrical impulses. Holter monitoring Holter monitoring is also called ambulatory electrocardiography. A Holter monitor is a machine about the size of a camera. The monitor makes a tape recording of your heart beating for a 24-hour period. The Holter monitor recording shows how your heart works during activity and rest.