Which of the following is listed as an AVNRT ablation endpoint?

• A. Ablation of slow pathway
• B. No AH jump
• C. 1 echo beat
• D. Non-inducibility

Answer: (C)

In AVNRT ablation, the aim is to modify the slow pathway within the AV node so that the reentrant circuit cannot be sustained, while keeping enough conduction to avoid AV block. A practical intra-procedural endpoint used to gauge adequate modification is the appearance of a single echo beat after programmed stimulation. This means the slow pathway conduction has been sufficiently weakened: you may still provoke a retrograde response once (an echo beat), but the circuit can no longer support repetitive or sustained reentry. It signals that enough modification has been achieved to prevent AVNRT, with a lower risk of inducing complete AV block.

Ablation of the slow pathway describes the procedure itself, not the immediate endpoint. No AH jump reflects a loss of dual AV nodal physiology but is not as specific a procedural endpoint by itself. Non-inducibility is a strong overall endpoint, but some protocols look for the more discrete finding of a single echo beat as a measurable intra-procedural sign of adequate slow-pathway modification.