[Intermittent pre-excitation after adenosine administration]. / Preexcitación intermitente tras administración de adenosina.

We describe a case of 2:1 intermittent preexcitation after adenosine administration in a patient with an accessory pathway that did not show preexcitation on the basal ECG. We review the mechanisms involved that explain this event and the possible utility of adenosine to show accessory pathways that do not show preexcitation on the ECG.