Complete AV block is seen as evidenced by the AV dissociation. A junctional escape rhythm sets the ventricular rate at 45 bpm. The PP intervals vary because of ventriculophasic sinus arrhythmia; this is defined when the PP interval that includes a QRS is shorter than a PP interval that excludes a QRS. The QRS generates a strong enough pulse to activate the carotid sinus mechanism, which slows the subsequent PP interval.
AV: atrioventricular.
With permission of Dr. Frank Yanowitz, University of Utah, from the Alan E. Lindsay ECG Learning Center in Cyberspace.
