Concealed junctional extrasystoles---a cause of pseudo AV block

Here's a case report and brief review.


Barney Marriott used to cite these red flags for the condition:


Abrupt, unexplaind (non-physiologic) lengthening in the PR interval.


Apparent “Mobitz II” AV block but with a normal conducted QRS (but intrahisian AV block can cause this too).


Manifest junctional extrasystoles seen elsewhere.


Electrophysiology at the bedside. Fascinating stuff.