P wave
Atrial systole-atria contraction
PR Interval
Delay of the electrical impulse at the AV node
QRS complex
Ventricular systole. Spread of electrical impulse passing to base of ventricles, through the walls. Ventricles contract immediately afterwards.
T wave
Relaxation of the ventricles, the beginning of ventricular diastole
Bradycardia
A slow heart rhythm
Ectopic heartbeat
An extra beat or an early beat of the ventricles
Fibrillation
An uncoordinated contraction of the atria and ventricles
Tachycardia
A rapid heart rhythm