Recurrent Supraventricular Tachycardia with a Different Retrograde Atrial Activation Sequence: What is the Mechanism?

UNLABELLED: A young man underwent 2 catheter ablation procedures because of frequent episodes of paroxysmal supraventricular tachycardia (SVT). A left accessory pathway was ablated in the first procedure. The patient underwent the second ablation procedure due to a recurrent SVT demonstrated by 12-lead electrocardiogram two weeks after the first procedure. During the second procedure, a SVT with a different retrograde atrial activation sequence was present. Programmed stimulation at the right ventricular apex showed multiple retrograde atrial activation sequences. Thereafter, careful analysis of the intracardiac electrograms helped us to successfully ablate the SVT. KEY WORDS: Ablation; Electrophysiology; Supraventricular tachycardia.