Ventricular Escape

 Twitter case from @ecgandrhythmRoe

 Seems to be some manner of escape rhythm, punctuated by Sinus capture.

 Hypothesis:

 The long horizontal lines demarcate zones of Atrium (A), AV node (AV), and Ventricles (V). 

The blue dots suggest a primary ventricular escape with successful retrograde conduction through the AV node, and into the Atrium. 

Suddenly, there is Sinus capture (green dot) with antegrade conduction into the ventricles. This Sinus impulse attempts to control the pace (orange dots), but is impeded because of restoration of the ventricular escape.