PO-01-005 GANGLIONATED PLEXI MEDIATED BRADYCARDIA RESPONSES: A PRE-CLINICAL STUDY OF DIFFERENCES BETWEEN PULSED FIELD AND RADIOFREQUENCY ABLATION IN THE LEFT ATRIUM

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During left atrial catheter ablation procedures, the peri-atrial neural network of ganglionated plexi (GP) can be affected by the ablative energy. Bradycardic responses (BR) from GP stimulation have been reported during both radiofrequency (RF) and pulsed field (PF) ablation procedures. To assess differences in BR between RF and PF during canine left atrial ablation. Healthy canines (n=14) underwent transeptal access under general anesthesia. A multielectrode spherical array catheter (Globe PF System; Kardium Inc., Canada) capable of both cardiac mapping and ablation with either RF or PF was deployed in the left atrium. For each application, electroanatomic maps with ostial tags, contact maps based on blood flow detection, and animated voltage maps were created to help verify isolation. Either temperature-controlled RF ablation (63°C for 3 minutes) or PF ablation (1.7-1.8 kV) was used to circumferentially isolate two PVs/animal and create a linear and focal lesion along the posterior wall and roof of the left atrium. GP stimulation as evidenced by BR was recorded if either sinus bradycardia or AV block was noted during and/or immediately after the pulse train (Figure). A total of 11 and 3 animals underwent PF and RF ablation, respectively. All ablations were successfully delivered to all locations without adverse events. Of the animals treated with RF, none (0 of 3) displayed any evidence of GP stimulation at any locations. All animals treated with PF showed evidence of GP stimulation: all animals (11 of 11,100%) exhibited BR during ablation at the inferior common vein, with 6 of 10 (60%) animals demonstrating BR at the roof and posterior wall (Table). BR of less severity was noted during subsequent pulse trains but remained most frequent at the inferior common vein. Ganglionated plexi-mediated bradycardic responses occur with PF ablation, with evidence of some degree of stunning when repeated pulse trains are delivered. This pre-clinical model with ablation at this location will serve as a good model to further our understanding of this phenomenon. The lack of any bradycardic responses with RF either represents a lack of stimulation (perhaps because of the inability of the RF energy to reach the epicardial GPs, unlike the volumetric nature of the pulsed electrical fields) or, complete ablation without stimulation. Further work is needed to explore these differences.