Which finding is a hallmark finding of Wolff-Parkinson-White syndrome on the ECG?

Which finding is a hallmark finding of Wolff-Parkinson-White syndrome on the ECG?

• A. Short PR interval
• B. ST segment elevation
• C. Delta wave
• D. Tall P waves

Answer: (C)

The key idea is pre-excitation of the ventricles through an accessory conduction pathway. In WPW, the impulse bypasses the AV node and reaches the ventricles early, which shows up on the ECG as a delta wave—the slurred upstroke at the beginning of the QRS complex. This delta wave is the most characteristic clue because it directly reflects the abnormal ventricle activation via the accessory pathway. A short PR interval often accompanies it, since conduction to the ventricle starts sooner, and can broaden the QRS as well, but the delta wave is the defining feature. ST segment elevation and tall P waves are not typical hallmarks of WPW and point to different conditions.

The key idea is pre-excitation of the ventricles through an accessory conduction pathway. In WPW, the impulse bypasses the AV node and reaches the ventricles early, which shows up on the ECG as a delta wave—the slurred upstroke at the beginning of the QRS complex. This delta wave is the most characteristic clue because it directly reflects the abnormal ventricle activation via the accessory pathway. A short PR interval often accompanies it, since conduction to the ventricle starts sooner, and can broaden the QRS as well, but the delta wave is the defining feature. ST segment elevation and tall P waves are not typical hallmarks of WPW and point to different conditions.