What are the variations for ventricular depolarization in Wolff-Parkinson-White (WPW) syndrome?

Updated: Jan 08, 2017
  • Author: Christopher R Ellis, MD, FACC, FHRS; Chief Editor: Mikhael F El-Chami, MD  more...
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Answer

The extent to which the wavefront over each route contributes to ventricular depolarization varies, as follows:

  • If delay in AV nodal conduction occurs from either rapid atrial pacing or a premature atrial complex, a greater proportion of the ventricle activates via the bypass tract, and the QRS becomes more preexcited
  • On the other hand, if the bypass tract is far from the sinus node (as in the presence of a left lateral pathway) or if AV nodal conduction is rapid, a larger proportion of the ventricle activates via the normal pathway, and preexcitation will be subtle
  • The normal fusion beat during sinus rhythm has a short or negative His-ventricle (HV) interval; pacing the atrium rapidly at premature intervals accentuates the abnormal ventricular depolarization and further shortens the HV interval
  • Localization of the potential site of pathway for RF ablation may be facilitated by analysis of the delta wave axis as initially described in the classic article by Arruda et al [28]

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