Electrocardiography (ECG or EKG)
Electrocardiography (ECG or EKG from the 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 electrocardiogram (ECG) is a test that records the electrical activity of the heart.
ECG is used to measure the rate and regularity of heartbeats as well as the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart (such as a pacemaker).
The etymology of the word is derived from the Greek electro, because it is related to electrical activity, kardio, Greek for heart, and graph, a Greek root meaning "to write". In English speaking countries, medical professionals often use "EKG" (the abbreviation for the German word Elektrokardiogramm) in order to avoid audible confusion with "EEG," in emergency situations where background noise is high.
Most EKGs are performed for diagnostic or research purposes on human hearts, but may also be performed on animals, usually for research.