A Concealed Typical AVNRT : U Wave Contribution in Simulating Long RP Supraventricular Tachycardia

ABSTRACT

Accurate identification of P waves on electrocardiogram (ECG) is essential in supraventricular tachycardias because U waves may resemble retrograde P waves, producing a pseudo–long RP interval and hiding typical atrioventricular nodal reentrant tachycardia (AVNRT). A 40‐year‐old woman presented with regular narrow‐complex tachycardia with a positive deflection immediately following the T wave, creating the impression of a long RP tachycardia. The electrophysiological study revealed a short VA interval with an H‐A‐V activation sequence, characteristic of typical slow‐fast AVNRT. This case emphasizes the diagnostic challenge posed by U waves at higher heart rates, which can obscure the true arrhythmia mechanism.