Abstract
An automatic scanning pacemaker (ASPM) was implanted to a patient with re-entrant tachycardia of WPW syndrome. Later paroxysmal atrial fibrillation (Af) had developed and the ASPM could not distinguish Af from re-entrant tachycardia and made ineffective stimuli to the right ventricle without any order, which had possibility of developement to ventricular fibrillation. Therefore it is better to say that ASPM is contra-indication for WPW syndrome which has potential to be accompanied with Af.
