Möbitz 2 AV Block

Report:

Sinus rhythm

Advanced second degree AV block, Möbitz 2

Ventricular pacemaker

Intermittent failure to xsense

Intraventricular conduction defect, unspecified

Comment:

The pacemaker was stopped after the first beat in the upper strip, turned on in the lower strip: this cannot be deduced from the strips and should not be reported. In clinical reporting, however, any relevant known information can and should be used.

The IVCD was a RBBB, seen in the 12-lead ECG below (Fig 123a) both in the junctional escapes and in the conducted sinus beats. The three escape beats appear to have a fixed relationship to the preceding P wave, raising the possibility of alternative diagnosis of dual pathway conduction. This is much less likely than the relationship being fixed by the (unrecorded) conducted sinus beat from which the original junctional escape cycle was set.

Möbitz 2 block is, almost always, intraventricular in location; hence its almost invariable association with a bundle branch block. It’s also much less common, clinically, than its

Wenckebach counterpart. Accordingly, it’s over-represented in this collection.