1. The graphic recording of the potentials of the heart detected on the surface of the body by electrocardiography.
2. A record of the electric currents produced in the body by the heart-beats of a patient. The electrocardiogram gives important information concerning the spread of excitation to the different parts of the heart, and is of value in diagnosing cases of abnormal cardiac rhythm and myocardial damage which refers to the muscular tissue of the heart.

An electronic instrument which obtains information by recording the differences in the voltages of two electrodes at different sites or parts of the surfaces of a body.

The usual electrocardiogram which plots voltage versus time, as distinguished from the vectorcardiogram, which plots voltage versus phase.

1. An electrocardiogram taken with the exploring electrode placed on the chest over the heart or upon a single limb, the indifferent ("zero" potential) electrode being the central terminal.
2. An electrocardiogram that shows the potential detected by a single electrode.

In practice, this is obtained by using an exploring electrode and a second electrode; such as, a central terminal that is assumed to have zero potential.