Graphic record of the heart's integrated electrical currents responsible for conducting a heartbeat and causing the cardiac muscle fibers to contract together to form the portions of a heartbeat- an ECG and EKG are both the same thing- the later shows deference to the Dutch Physicist Einthoven who created the technology and named the leads in his 1895 paper. Noticing a recurring pattern of movement, Einthoven named the prominent waves alphabetically, P, Q, R, S, and T: the P-Wave, representing the impulse across the atria to the A/V Node; the QRS representing the impulse as it travels across the ventricles; the T-Wave, representing the repolarization of the ventricles