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Assoc Prof Harry Mond
December 17, 2024
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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.
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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.
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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?).
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October 14, 2026
Retrograde conduction is defined as conduction from an ectopic site to the atrium via the AV node or accessory pathway and referred to as VA conduction. II results in a P wave configuration which differs from an anterograde P wave, and in most ECG leads is inverted. The site from where the impulse originates can be the AV node, Bundle of His, distal conducting system or the body of the ventricles including ventricular pacing. On the ECG, the QRS complex usually precedes the inverted retrograde P wave but on occasion may follow it.
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