Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ ECG Findings ++ Normal P waves Shortened PR interval Prolonged QRS interval Delta waves (slurring of the initial upstroke of R wave) ++ Pearls ++ Accessory tracts from the atria to the ventricles lead to depolarization of ventricles without using the AV node as the primary connecting route. Tachycardia associated with WPW may be mistaken for VT. Suspect WPW if the QRS complex is wide and tachycardia is extreme (ventricular rate > 240). Do not treat irregular atrial tachycardias (atrial fibrillation) in the setting of WPW with AV nodal blocking agents (calcium channel blockers, β-blockers, digoxin). This may lead to unopposed ventricular stimulation through the accessory tract and may worsen the tachycardia. Procainamide and cardioversion are accepted methods for conversion of a tachycardia associated with WPW. Depolarization via the accessory pathway may produce “pseudo-Q waves.” ++ FIGURE 23.44A Wolff-Parkinson-White Syndrome. (ECG contributor: James V. Ritchie, MD.) Graphic Jump LocationView Full Size|Favorite Figure|Download Slide (.ppt) ++ FIGURE 23.44B The PR interval is shortened (double arrow) and a delta wave (upsloping initial QRS segment) is seen (arrow, shaded area). Graphic Jump LocationView Full Size|Favorite Figure|Download Slide (.ppt) GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessEmergency Medicine 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessEmergency Medicine Full Site: One-Year Individual Subscription $595 USD Buy Now View All Subscription Options