Cardiac Rhythm Series: Wolff-Parkinson-White (WPW) Syndrome

Wolff-Parkinson-White (WPW) Syndrome is a condition where an accessory (extra) electrical pathway exists between the atrium and the ventricles that bypasses the AV node1, 2. The additional conduction pathway, known as the Bundle of Kent, is faster than the normal SA-AV-HIS-Purkinje pathway1. The impulses can travel around the heart very quickly causing the heart to beat unusually fast.

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The hallmark sign of WPW is an upswing coming off the base of the P-wave going diagonally to the top of the R-wave– this is known as a delta wave1. Below you can see an example of the abnormal waveform caused by WPW:

Photo retrieved from

WPW is a genetic defect occurring in approximately 2/1000 people with 60-70% of all cases being men1. About 70% of cases have no evidence of cardiac disease, and this condition often goes unnoticed unless an individual presents to the ED with an arrhythmic event1. Symptoms may include chest pain, dizziness, lightheadedness, shortness of breath, and fainting.

The only effective treatment for WPW is ablation of the accessory pathway1. Medications that block the AV node (beta-blockers, calcium channel blockers) should be avoided otherwise a terminal tachycardia that is nearly impossible to treat may develop1.

  1. University of Maryland Medical Center Office of Clinical Practice and Professional Development. (2014). Introduction to cardiac rhythm interpretation (6th ed.).
  2. Bojar, R. M. (2016). Manual of perioperative care in adult cardiac surgery (5th ed.). West Sussex, UK: Wiley-Blackwell

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