12-lead electrocardiogram (ECG) showing antidromic atrioventricular reentrant tachycardia (AVRT) in a patient with an accessory AV pathway

The 12-lead ECG of a patient with Wolff-Parkinson-White shows a regular tachycardia. The QRS complexes are widened and are identical to the QRS complexes seen in sinus rhythm; the antegrade conduction to the ventricle is via the accessory pathway and retrograde conduction is via the normal His-atrioventricular node pathway. This is, therefore, an antidromic atrioventricular reentrant tachycardia (AVRT).

The 12-lead ECG shows the typical features of Wolff-Parkinson-White; the PR interval is short (*) and the QRS duration prolonged as a result of a delta wave (arrow), indicating ventricular preexcitation.