APA Dictionary of Psychology

n. a wavelike tracing, either printed or displayed on a monitor, that represents the electrical impulses of the conduction system of the heart muscle as it passes through a typical cycle of contraction and relaxation. The electrical currents are detected by electrodes attached to specific sites on the patient’s chest, legs, and arms and recorded by an instrument, the electrocardiograph. In the procedure, which is called electrocardiography, the wave patterns of the electrocardiogram reveal the condition of the heart chambers and valves to provide an indication of possible cardiac problems.