ECG Intervals and Waves-KH
Frank G. Yanowitz, M.D., copyright 1997
The P wave represents atrial activation; the PR interval is the time from onset
of atrial activation to onset of ventricular activation. The QRS complex
represents ventricular activation; the QRS duration is the duration of
ventricular activation. The ST-T wave represents ventricular repolarization. The
QT interval is the duration of ventricular activation and recovery. The U wave
probably represents "afterdepolarizations" in the ventricles.