Pacemaker-Ventricular 2:1 Block

Report:

Sinus rhythm 94/min 1

Atrial-sensing ventricular pacemaker rhythm 4

AV block (unspecified) 1

2:1 pacemaker-ventricular block 4

Comment:

T wave’s more trouble than it’s worth. One cannot be sure whether we are dealing with sinus rhythm 94/min or sinus rhythm 47/min with atrial bigeminy: the contour of the blocked atrial waves is largely hidden in T waves. True, they appear to have slightly shorter cycles – a fact recognised by the pacemaker, atrial-sensing, spikes. This is of little value in the face of a likely ventriculophasic sinus arrhythmia associated with 2:1 conduction.

The bigeminal SVEBs (or sinus P waves sped up by the aforesaid ventriculophasic effect) are obviously blocked – no native QRS complexes are present. They are in fact “blocked” again, through the failure of the pacing spikes to activate the ventricle. They are, so to speak, doubly blocked! That’s why we can be sure that (some) native AV block is present as well. Some, because one cannot rule out some conduction at a different rate.

A normally functioning pacemaker was present two months previously (below).