ECG

An ECG is used to measure the electrical activity of the heart treated as a vector quantity. It measures the rate and regularity of heartbeats, the position of the various chambers, the existence of any damage to the heart and the effects of drugs and devices used to regulate the heart.

The potential created by the heart wall contraction spreads electrical currents from the heart throughout the body. The spreading electrical currents create different potentials at different points on the body. Leads are placed on the body in several pre-determined locations to provide information about heart conditions. The cardiac signal, typically 5 mV peak to peak, is an AC signal with a bandwidth of 0.05 Hz to 100 Hz (Section 4). The ECG signal is characterized by six peaks and valleys labeled with successive letters of the alphabet P, Q, R, S, T, and U.