Electrocardiography
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.
Read more about Electrocardiography.