QRS complex

(medicine) The electrocardiographic deflection representing ventricular depolarization; the initial downward deflection is termed a Q wave; the initial upward deflection, an R wave; and the downward deflection following the R wave, an S wave. Also known as ventricular depolarization complex.

The largest component of an electrocardiograph. It corresponds to ventricular depolarization and, at rest, normally lasts less than 0.1 s.

The principal deflection in the electrocardiogram, representing ventricular depolarization.