Which factors increase preexcitation 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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A negative HV interval during sinus rhythm in the presence of WPW syndrome means that the His deflection occurs after the beginning of the QRS deflection. The more preexcitation, the later the His deflection (ie, more toward the end of the QRS).

This occurs whenever the AP conducts more rapidly than the AV node and the depolarizing wavefront from the AP thus reaches the ventricle before that from the AV node. The earlier that the depolarization from the AP reaches the ventricle with respect to the depolarization from the AV node, the more preexcitation occurs (ie, the wider the QRS and the shorter the RP interval).

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