Delta wave
Also calleddelta wave · pre-excitation slur · WPW slurring · slurred QRS upstroke
Definition
A slurring of the initial part of the QRS complex caused by ventricular pre-excitation, when an accessory pathway that bypasses the AV node conducts the atrial impulse to the ventricles. It interrupts the end of the P wave or arises right after it. On the surface ECG it comes with a short PR interval (under 120 ms in adults) and, with full pre-excitation, a QRS longer than 120 ms and secondary ST and T-wave changes: the Wolff-Parkinson-White pattern.
Clinical noteThe ECG findings alone are the WPW pattern; together with symptomatic episodes of paroxysmal supraventricular tachycardia they make up WPW syndrome.
Sources
- Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances. Circulation. 2009;119(10):e235-e240. doi.org/10.1161/CIRCULATIONAHA.108.191095
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.