Catheter Ablation -> SVT/AVNRT/WPW/AT: -> Mapping & Imaging D-PO05 - Poster Session V (ID 39) Poster

D-PO05-159 - Physiology Of Slow Pathway Conduction During Sinus Rhythm: Evidence From High Density Mapping Within The Triangle Of Koch (ID 1284)

 S.J. Bailin: Nothing relevant to disclose.


Background: We have previously described a methodology for visualization of the slow pathway using voltage gradient mapping. By adjusting voltage limit values, the slow pathway could be identified by the presence of a low voltage bridge (Navix, SJM). Activation within this LVB occurs both superiorly via the fast pathway and inferiorly via the slow pathway. In order to further evaluate this interaction, we used an Orion high density basket (Rhythmia, BSC) to map sinus rhythm. 10 consecutive patients undergoing electrophysiology testing for AVNRT were mapped in sinus rhythm, both activation and voltage gradient were evaluated.
Objective: To define conduction activation within the triangle of Koch in patients with AVNRT
Methods: Patients undergoing evaluation for AVNRT had mapping in Sinus rhythm by a HD system (Orion, Rhythmia). Both activation and Voltage mapping was performed.
Results: Activation mapping universally identified conduction from the fast pathway moving inferiorly toward the CS and activating the His transversely. Activation then pivots superiorly along the TV toward the AV Node. This channel and pivot point is associated with the previously described slow pathway LVB. See figure.
Conclusion: Antegrade conduction in the presence of dual AV nodal physiology occurs via dual inputs into the AV Node. One occurs transversely from the fast pathway and the other, inferiorly following a pivot of activation around a line of block within the triangle of Koch. The position of this pivot point, inferior to the node and near the TV may explain the complex electrogram associated with successful anatomic/electrogram directed ablation.