AV Dissociation With Interference

Report:

Sinus tachycardia 115/min

Second degree AV block, probably Möbitz 1 (Wenckebach) type

Wenckebach pauses with two blocked P waves?

Junctional escape beats and rhythm?

Comment:

This is a surprisingly difficult strip to interpret completely. While it is possible that all the ventricular beats are conducted sinus impulses, it is more likely that at least some cycles are terminated by junctional beats. The simplest hypothesis is that there are some sinus captures; the rest are dissociated junctional beats. Simplicity is all it has to offer.

This may be an example of Wenckebach periods with two, instead of one, dropped P waves. Another impediment to measurements is the possible operation R-P – P-R interval reciprocity

A period of 3:1 conduction is shown below (Fig 65a), in the second strip. This indicates the possibility of a two-level block, more often seen in atrial tachycardias or flutter.

Sometimes yards of paper are perused in the hope that a unifying, simple explanation will be obtained from a representative segment. Sometimes, as here, the explanation is yet to come.

Fig 65a. Perhaps the simplest description would be sinus tachycardia with variable 2o AV block! Not scholarly, but descriptive enough.

Fig 66. 77 year old man with recurrent pre-syncope over the past fortnight.