Lean Child of Fat Parents

Report:

Sinus rhythm 60/min 1

First degree AV block 1

Right bundle branch block 1

AV sequential pacemaker rhythm 60/min 1

No atrial capture 1

Ventricular pacemaker rhythm 60/min 1

Superior electrode displacement 1

Fusion beats 3

Comment:

The temporary pacemaker was inserted due to intermittent failure of the sequential (in fact, DDD) pacemaker. It is interesting that the two pacemakers have the same rate as the underlying sinus rhythm. This provides grounds for ventricular fusion beats, the first of which is the normal-looking complex (but in reality no more normal than an android). As Schamroth put it, two wrongs can make a right! The fat LBBB-like paced beat and the plump RBBB sinus beat fused to create a lean QRS complex. The next beat is also fusion, but with much less sinus contribution; the last beat is pure pacemaker complex, the preceding P wave being too close to hope for any conduction.

The temporary pacemaker has its tip displaced upward, toward the RV outflow tract. This is a wobbly position in a most irritable part of the ventricle but is often accepted with surprising impunity. I have seen many more Swan-Ganz catheters than pacemakers cause serious arrhythmia in this region.