| Abstract: | Background: A‐63 year‐old man complaining of palpitations underwent a 24‐hour ambulatory ECG monitoring that revealed the presence of recurrent episodes of nonsustained supraventricular tachycardia. Analysis of the tracings suggests an atrial origin of the arrhythmia. Tachycardias, quite regular at the beginning, suddenly showed a P‐P cycle alternans, namely, P‐P intervals alternately short and long. The evidence of two separate cycle ranges can be explained by the presence of a longitudinal dissociation within a discrete zone of the atrial circuit. |
