Second Degree AV Block

Report:

Sinus rhythm

One cycle episode of second degree AV block

Comment:

The patient kept no diary, but it is safe to presume she was asleep at 4 am. What is one to make of her blocked P waves (there was another, below)? Probably nothing, given that no other cardiac abnormalities came to light. Healthy young subjects may get episodes of AV block, especially during sleep75.

This is an example of apparent type 2 block, discussed in the footnote of Case 109.

If she had frequent VEBs or junctional extrasystoles, a pseudoblock from non-conducted main-stem extrasystole could have been a possibility. The strip below shows two extrasystoles, both junctional (the second one with phasic aberrant conduction) following the blocked P wave. But they are in the wrong place: the first is an escape beat caused by the block rather than causing it and the second one may be just a result of the preceding pause, illustrating the rule of bigeminy.

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