Advanced 2o AV Block

Report:

Top:

Sinus rhythm 94/min

Bottom:

Sinus rhythm 94 – 102/min

Advanced second degree AV block

Comment:

The block is called advanced (high-grade) if less than 50% of P waves are conducted.

It would be easier to understand a vagally mediated AV block if the sinus rate slowed at the same time. It is not known whether this block was Wenckebach or Möbitz 2 in type, since its onset had not been recorded. Even the apparent Möbitz 2 block70 occurring in the setting of vagally induced slowing of the sinus rate is a relatively benign phenomenon, rarely requiring pacing71. To my knowledge, neither hyperprolactinæmia nor bromocryptine used to control it are causes of AV block.

This case is similar to Case 131: an essentially healthy young woman with episodes of unexplained high-grade AV block and seemingly unrelated intracranial pathology.

In the absence of systemic or pharmacological causes, one has to think of local ones, like the mesothelioma of the AV node. The intermittent nature of the block is not, necessarily, against it at presentation. It is, however, vanishingly rare.

The association of demonstrated AV block with syncope makes permanent pacing mandatory. Her interval ECGs (Fig 109b) were completely normal.