Atypical atrioventricular nodal reentrant tachycardia

Shown are three simultaneous ECG leads (I, II, and III) during an uncommon or atypical form of an atrioventricular nodal reentrant tachycardia (AVNRT) in which antegrade conduction to the ventricle is via the fast pathway and retrograde atrial activation is by the slow pathway. As a result of delayed atrial activation, there is a long RP and short PR interval and a negative P wave in the inferior leads II and III.