ATYPICAL ATRIOVENTRICULAR NODE RECIPROCATING TACHYCARDIA MASQUERADINGAS TACHYCARDIA USING A LEFT-SIDED ACCESSORY PATHWAY

Objectives. The study was performed to document that atrioventricular node reciprocating tachycardia (AVNRT) can be associated with eccentri c retrograde left sided activation, masquerading as tachycardia using a left accessory pathway. Background. The eccentric retrograde left-si ded activation during tachycardia is thought to be diagnostic of the p resence of a left free wall accessory pathway, However, it is not know n whether AVNRT can occur with eccentric retrograde left sided activat ion. Methods. We studied 356 patients with AVNRT who underwent cathete r ablation, Retrograde atrial activation during tachycardia and ventri cular pacing were determined by intracardiac recordings, including the use of a decapolar coronary sinus catheter. Results. The retrograde a trial activation was eccentric in 20 patients (6%), Eight of these pat ients had the earliest retrograde atrial activation recorded in the la teral coronary sinus leads, and 12 had the earliest retrograde atrial activation recorded in the posterior coronary sinus leads, with the mo st proximal coronary sinus electrode pair straddling the coronary sinu s orifice, These tachycardias were either the fast slow or the slow-sl ow form of AVNRT, The slow fast form of AVNRT was also inducible in 17 of the 20 patients, Successful ablation of the slow pathway in the ri ght atrial septum near the coronary sinus ostium prevented the inducti on and clinical recurrence of reciprocating tachycardia in all patient s. Conclusions. Atypical AVNRT with eccentric retrograde left sided ac tivation was demonstrated in 6% of all patients with AVNRT masqueradin g as tachycardia using a left sided accessory pathway, Ablation of the slow pathway at the posterior aspects of the right atrial septum resu lted in a cure in these patients. (C) 1997 by the American College of Cardiology.