P wave?
Atrial depolarisation.
QRS complex?
Ventricular depolarisation.
T wave?
Ventricular repolarisation.
PQ segment?
AV nodal delay.
QT segment?
Ventricular systole.
TQ interval?
Ventricular diastole.
What’s A?

P wave.
What’s B?

QRS complex.
What’s C?

T wave.
What’s D?

P-Q.
What’s E?

R-R.
What’s F?

T-Q segment.
What’s G?

Q-T segment.