INTRODUCTION:
Atrioventricular nodal re-entrant tachycardia (AVNRT) is the most common cause of
supraventricular tachycardia (SVT)1-6. Slow pathway ablation is the first line treatment for recurrent symptomatic AVNRT with high long term success2, 3, 5, 7-15, however heart block requiring pacemaker implant can occur in up to 1%16-18
AVNRT is the archetypal re-entrant tachycardia utilizing functionally distinct but anatomically variable inputs within a transitional zone of junctional tissue within the triangle of Koch termed the slow and fast pathways5, 19-23. Initial ablation strategies targeted the fast pathway with an unacceptable incidence of AV block24. In recent times the slow pathway has been established as the target for ablation with junctional rhythm generally required to achieve acute success7. Although there is general consensus regarding the need for junctional rhythm during RF, retrospective studies reporting the characteristics of junctional rhythm during RF required for successful slow pathway modification have been inconclusive 25-27.
The purpose of the present study was to prospectively evaluate the effect of each and every radiofrequency (RF) application in the region of the slow pathway to determine if junctional rhythm can predict procedural and long-term success.