Nodal (A-V junctional) rhythm C13, R8  

In junctional rhythm, the heart's atrioventricular node takes over as the heart’s pacemaker (typically at rates of 40-60 BPM) The atria will still contract before the ventricles through a backwards or retrograde conduction (conduction comes from the AV node into and through the atria). On the ECG, junctional rhythm usually presents with a missing or inverted P-wave. Retrograde P-waves refers to the depolarization from the AV node back towards the SA node.

Rhythm Strip
Nodal (A-V junctional) rhythm Rhythm Strip

Junctional/Nodal Rhythm interrupted by SVEB and VEB then return to Sinus Rhythm

12 Lead EKG
Nodal (A-V junctional) rhythm 12 Lead EKG