What they look like

How the sensor works

An electrocardiogram (ECG or EKG) is a recording of the electrical activity of the heart over time produced by an electrocardiograph, usually in a noninvasive recording via skin electrodes. In the US, the abbreviation "EKG", (abbreviated from the German Elektrokardiogramm) is often preferred over "ECG", while "ECG" is used universally in the UK and many other countries. It is preferred as "EKG" in the US and most of the former USSR countries because doctor’s handwriting of "ECG" can often be confused as "EEG" when transcribing orders or with echocardiography which is also abbreviated "ECG".

Electrical impulses in the heart originate in the sinoatrial node and travel through the heart muscle where they impart electrical initiation of systole or contraction of the heart. The electrical waves can be measured at selectively placed electrodes (electrical contacts) on the skin. Electrodes on different sides of the heart measure the activity of different parts of the heart muscle. An EKG displays the voltage between pairs of these electrodes.

Where it can be used

• Resting EKG
• EKG after exercise
• EKG and different body positions
• EKG after using mild stimulants such as coffee or coca-cola