The ECG Rhythms content is currently under development and is being updated by medical professionals.
Wolff-Parkinson-White (WPW) syndrome is a congenital heart condition characterized by the presence of an extra electrical pathway between the atria and the ventricles, known as an accessory pathway or the bundle of Kent.190 This extra pathway allows electrical impulses to bypass the AV node and directly excite the ventricles, leading to pre-excitation.190
Analogy: “An extra shortcut in the orchestra allowing some instruments to play slightly ahead of the main conductor’s signal.”
The ECG in WPW syndrome typically shows a constellation of characteristic findings.192 The PR interval is short, measuring less than 0.12 seconds (or < 3 small squares), because the impulse bypasses the normal AV nodal delay.190 The QRS complex is widened, with a duration greater than 0.12 seconds (or > 3 small squares), and exhibits a slurred upstroke, which is referred to as a delta wave.190 This delta wave represents the early activation of the ventricles via the accessory pathway. Secondary ST-T wave changes may also be observed due to the altered sequence of ventricular depolarization.190
Individuals with WPW syndrome may experience episodes of rapid heartbeats, known as palpitations, which can be described as a fluttering or pounding sensation.190 Other symptoms can include dizziness, lightheadedness, and syncope (fainting).190 Some individuals may also experience shortness of breath or anxiety during these episodes.190 WPW syndrome carries a risk of supraventricular tachycardia (SVT) due to the potential for re-entrant circuits involving the accessory pathway.190 Additionally, patients with WPW syndrome who develop atrial fibrillation are at risk of a rapid ventricular response, which can sometimes degenerate into ventricular fibrillation.190 It’s important to note that some individuals with the WPW pattern on their ECG may remain asymptomatic throughout their lives.190
“Like a shortcut allowing some musicians to jump ahead, the accessory pathway causes early activation of the ventricles.”