Atrial Fusion Beats

Report:

Sinus rhythm

Junctional ? atrial rhythm

Shifting (atrial) pacemaker

Atrial fusion beats

AV dissociation

Probable third degree AV block

Pacemaker rhythm 63/min

Comment:

Again, this is a "trick" question, designed to make one look (in vain) for ventricular fusion beats. The fusion is confined to the atria, at the transition between the two atrial pacemakers. As Schamroth said: The obvious is obvious. Look elsewhere10.

The complete heart block is only a presumption here - it is possible that some AV conduction would occur if the ventricular pacemaker were slower or the atrial rate faster.

If you have any suggestions for or feedback on this report, please let us know.