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Arrhythmias
 
 

Wolff-Parkinson-White Syndrome

 
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Overview

  • Wolff-Parkinson-White (WPW) syndrome is a congenital cardiac pre-excitation syndrome that occurs due to the presence of an accessory conduction pathway.

Pathogenesis

  • Normal cardiac impulses are conducted from the atria to the ventricle via the AV node. In WPW, an accessory pathway (the Bundle of Kent) is present which bypasses the normal conduction pathway. This produces a classic preexcitation pattern on ECG, and places the patient at risk of arrhythmias.
    • Types of Pre-Excitation

    • Manifest preexcitation - anterograde conduction through the accessory pathway, with retrograde conduction back up the AV node
    • Concealed preexcitation - anterograde conduction through the AV node, with retrograde conduction back up the accessory pathway
  • Manifest preexcitation produces the classic ECG findings listed below, while concealed preexcitation may produce no ECG changes at rest.

Diagnosis

    • ECG Findings in WPW

    • Resting ECG

    • Short PR interval <120ms
    • Delta wave - slow rise of the initial portion of the QRS complex
    • Prolonged QRS duration >120ms
    • ST / T wave changes
    • Associated Arrhythmias

    • AV re-entrant tachycardia - a regular tachycardia with P waves during or after the QRS complex (orthodromic) or broad complex tachycardia (antidromic)
    • Atrial fibrillation - an irregular broad complex tachycardia
    • Atrial flutter - a regular broad complex tachycardia
    • Diagnosis
       
  • The presence of an accessory pathway is part of the differential diagnosis for wide complex tachycardia, as an accessory pathway coupled with a tachycardia of supraventricular origin can produce a wide complex rhythm ressembling ventricular tachycardia.
 
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