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Wenckebach without a pause!

By Assoc Prof Harry Mond
December 19, 2019

This week we had a Holter monitor recording reported as complete heart block. For obvious reasons this can be a serious diagnosis, but the reporting cardiologist felt it was Wenckebach sequences and requested a review.

Wenckebach sequences almost always have a generous pause at the termination of a sequence.

A blocked P wave

In the above example, the blocked P wave extends the R to R interval from about 1000 ms to 1900 ms.
Sometimes this interval is shorter when the preceding PR interval becomes very long and the blocked P wave occurs immediately following the previous T wave.

Can the pause disappear?

In the following tracing, there is no pause because the blocked P wave is concealed within the QRS of the previous beat. which has a very long PR interval (or is it a junctional escape beat?).

  • The P waves are regular and may be concealed
  • There is a 3:2 Wenckeback sequence or a 3:1 sequence with a junctional escape
  • The timings almost obliterates the pause
  • The difference R-R intervals excludes complete heart block

Can you see the confusion with complete heart block?
This is surely a “rebel without a pause”.

Assoc Prof Harry Mond

About Assoc Prof Harry Mond

In 49+ years as a practicing cardiologist, Dr Harry Mond has published 260+ published manuscripts & books. A co-founder of CardioScan, he remains Medical Director and oversees 500K+ heart studies each year.

Download his full profile here.

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