High Quality Content by WIKIPEDIA articles! Electrocardiography (ECG or EKG from German: Elektrokardiogramm) is a transthoracic (across the thorax or chest) interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body. The recording produced by this noninvasive procedure is termed as electrocardiogram (also ECG or EKG). An ECG test records the electrical activity of the heart.