B-PO05-131 TYPICAL BRIDGE FOR ATYPICAL AVNRT

Abstract

Lower ablation success rates have been associated with atypical AVNRT. Evidence for ablation strategies for atypical AVNRT remain limited due to low prevalence. Anatomical ablation and identification of slow pathway through retrograde conduction have been reported. Voltage gradient mapping guided ablation has been evaluated in typical, “slow-fast” AVNRT. We describe two cases of atypical AVNRT that were successfully treated with targeting low voltage bridge for catheter ablation. N/A A 19yo man with symptomatic SVT presented for EPS and ablation. During EPS, tachycardia was initiated with atrial extrastimuli, and atypical AVNRT was diagnosed using standard pacing maneuvers (Figure, Panel A). A voltage map was created during sinus rhythm and low voltage bridge was identified (Figure, Panel B). Additionally, earliest atrial activation was mapped during tachycardia and localized to low voltage bridge (Figure, Panel C). RFA lesions were delivered over the low voltage bridge with associated junctional beats. He was non-inducible and is arrhythmia-free in follow up. Another case of atypical AVNRT in a 42yo male was approached similarly. Low voltage bridge was identified with voltage mapping during sinus rhythm and subsequently earliest atrial activation in tachycardia was identified. This case also demonstrated overlap in the localization of earliest atrial activation during tachycardia and low voltage bridge. To our knowledge, these are the first reported cases of atypical AVNRT successfully ablated by identifying a low voltage bridge, which correlated to site of earliest atrial activation, as a target for ablation.