ECG

An electrocardiography (ECG) is the electro-physiological measurement of the heart muscle signal. An ECG is suitable for measuring the heart rate and the regularity of heartbeats (heart rate variability or HRV). A typical ECG tracing of the cardiac cycle (heartbeat) consists of a P wave, a QRS complex and a T wave. The R-peak indicates the contraction phase (of the ventricles). The distance between the R-peaks (the interbeat interval (IBI)) defines the heart rate (HR). ECG can be measured by placing the electrodes on the left and the right wrist or by a vertical chest placement.

During each heartbeat, the heart contracts and pumps blood through the arteries and blood vessels. During each contraction tiny bits of electrical charge are produced, which can be recorded with electrodes placed at the surface of the skin. The resulting ECG (ElectroCardioGram) is a non-invasive method for measuring heart rate.

The electrical waveform of the ECG shows the multiple steps during each heartbeat. At rest, each heart muscle cell has a negative charge. Decreasing this negative charge towards zero is called depolarization, which activates the mechanisms in the cell that cause it to contract.

A typical ECG tracing of the cardiac cycle (heartbeat) consists of a P wave, a QRS complex and a T wave. The R-peak indicates the contraction phase of the ventricles of the heart. The distance between the R-peaks (the interbeat interval (IBI)) defines the heart rate (HR).