Atypical atrioventricular nodal reentry tachycardia with eccentric retrograde left-sided activation of coronary sinus.

BACKGROUND Recent anatomical and electrophysiological studies have demonstrated that in the human atrioventricular node there are two main extensions, the rightward and leftward posterior nodal extension (LPNE). The occurrence of eccentric retrograde atrial activation has been demonstrated in several previous reports to be from 6 to 8% in patients with AVNRT. OBJECTIVES The study was performed to confirm that standard right atrium ablation is effective and successful for atrioventricular node reentry tachycardia (AVNRT) with eccentric retrograde left-sided activation, masquerading as a tachycardia which looks like a tachycardia, using the left accessory pathway. METHODS AND RESULTS During a 7 years period (from 2002 to 2008), 865 consecutive patients underwent electrophysiological study. In the group with atrioventricular node reentry tachycardia (AVNRT) there were 178 patients. In the group with typical fast-slow AVNRT (162 pts) there was concentric retrograde activation of both the atria. The 16 patients had atypical AVNRT (10 pts with slow-slow AVNRT and 6 pts with LPNE). The ablation was performed, in all patients in the Koch's triangle on the slow pathway of the atrioventricular node. The successful rate of ablation was 99.4% (177/178 pts). The incidence of AVNRT with eccentric retrograde activation was 3.4%. In the follow-up period (16±12 months), there was no recurrence of AVNRT in the group with LPNE. CONCLUSIONS This study demonstrated the different electrophysiologic characteristics between the AVNRT patients with eccentric and concentric retrograde atrial activation. Standard ablation, but a little bit higher in the Koch's triangle, closer to the fast pathway, in the right atrium is effective and successful for AVNRT with retrograde left eccentric conduction in the coronary sinus.