Right atrial flutter (AFL) is a common form of macro reentrant arrhythmia. In absence of previous cardiac surgery, the reentry circuit is usually
bounded anteriorly by the tricuspid
annulus (TA) and posteriorly by the ostia of vena cava and Eustachian ridge. In this case, AFL is consensually called “typical” AFL and is highly dependent of the cavotricuspid isthmus (CTI). The CTI is a critical channel which represents the predominant area of
slow conduction of
the circuit. Therefore, this narrow isthmus has become the universally
accepted target
for ablation
of typical AFL.
If ablation is carried
out during AFL the first
“intuitive” procedure endpoint is arrhythmia termination. Although this latter
was initially thought to be an acceptable endpoint for ablation procedure, bidirectional CTI
conduction block validated 30 minutes after end of ablation, is actually
considered as the gold standard
endpoint for elimination of typical AFL recurrence. Indeed, Schumacher et al. found a 9% recurrence rate after bidirectional CTI block achievement, 54% recurrence rate after unidirectional CTI
block and 100% recurrence rate when persistent slow conduction across
CTI was noted after
RF application on the CTI.
Credits: Michaël Peyrol, MD; Pascal Sbragia, MD