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.