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Assoc Prof Harry Mond
February 23, 2026
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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).
July 16, 2026
I came upon these ECG tracings of ventricular tachycardia from a Holter study in a 79-year old asymptomatic female. What do you think?
July 9, 2026
No tricks. Just a selection of tracings from a Holter study.Look at each one carefully, use calipers, arrows and highlight and write down your conclusions.
July 2, 2026
I came across these two tracings from the same patient during Holter reporting. Do you agree with the reported diagnoses?
