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
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).
In 49+ years as a practicing cardiologist, Dr Harry Mond has published 260+ published manuscripts & books. A co-founder of our parent company CardioScan, he remains our Medical Director and oversees 500K+ heart studies each year.
See Dr Mond’s full profile here