Sinus bradycardia occurs on an ECG when there is a normal upright P wave in lead II ― sinus P wave ― preceding every QRS complex with a ventricular rate of less than 60 beats per minute.

The morphology of the P wave will not be similar to the sinus P wave ... electrolyte disturbances — is found. The strip below shows a junctional rhythm with retrograde P waves seen just before ...