P wave—atrial depolarization.
PR interval—time from start of atrial
depolarization to start of ventricular
depolarization (normally 120-200 msec).
QRS complex—ventricular depolarization
(normally < 100 msec).
QT interval—ventricular depolarization,
mechanical contraction of the ventricles,
ventricular repolarization.
T wave—ventricular repolarization. T-wave
inversion may indicate ischemia or recent MI.
J point—junction between end of QRS complex
and start of ST segment.
ST segment—isoelectric, ventricles depolarized.
U wave—prominent in hypokalemia (think
hyp“U”kalemia), bradycardia.
