Which findings on EPS suggest 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...
  • Print

Features of preexcitation

If a Kent bundle (AV)-type accessory bypass tract conducts in an antegrade fashion, two parallel paths can potentially carry the impulse. The first is the natural one, which comes with inherent physiologic delay over the AV node (decremental conduction). The second is the bypass tract (Kent bundle), which allows the impulse to pass directly without delay from the atrium to the ventricle (nondecremental conduction).

This dual-path mechanism produces a unique QRS complex that is a form of fusion beat. The delta wave results from ventricular activation by the impulse traveling over the AP. The degree of delta (preexcitation) is directly related to the distance of the bypass tract to the sinus node and the speed of conduction over the AV node and His Purkinje system.

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!