Assoc Prof Harry Mond
December 2, 2024
A Holter monitor report from an overseas customer was recently returned with a note pointing out that we had missed the diagnosis of intermittent pre-excitation - the Wolff-Parkinson-White Syndrome.
On inspection of the tracings, sure enough there were frequent complexes that had a short PR interval and a delta wave (highlighted).Did we actually miss this diagnosis?On careful inspection, each of these complexes occurs when the rhythm transitions from a narrow sinus rhythm with a normal P wave and PR interval to a broad QRS rhythm with no P wave. This is an idioventricular rhythm, rate 60-70 bpm and the complexes with a short PR interval and delta wave are fusion beats.Remember fusion causes confusion. This can be called pseudo-WPW.With Wolff-Parkinson-White syndrome, pre-excitation can be intermittent
And alternating!
Sometimes the delta wave is unusual.
What other situations can cause pseudo-WPW?
Late ventricular ectopics (VE) and fusion (F1, F2), all highlighted.
This is an example of isorhythmic AV dissociation with the alternating junctional escape beats fused with the sinus P waves resulting in a pseudo-WPW appearance (highlighted).
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May 14, 2025
Fusion is another lesson in timing! Fusion beats are an amalgam of two competing rhythms. Both are responsible for partial depolarization of the respective chambers and depending on the contribution of each, result in progeny with similarities to one or both parents.
May 14, 2025
The ventricular ectopic compensatory pause is a lesson in timing!
