PO-03-037 FEASIBILITY OF UNIPOLAR SIGNAL GUIDED ABLATION IN CREATING CONTIGUOUS LINES OF CONDUCTION BLOCK: A PROOF-OF-CONCEPT STUDY

Abstract

Contemporary ablation is guided by non-physiological surrogates such as Ablation indexTM (ABi). Dynamic changes in local atrial unipolar electrogram (Uni-EGM) with loss of the negative S component or “R-pattern” change during radiofrequency ablation (RFA) predicts a transmural lesion. To investigate the feasibility of generating contiguous, transmural lesions that result in conduction block, using ablation guided by Uni-EGM modification. This method was compared with ablation guided by standard ABi parameters. In a beating heart Yorkshire swine model, linear transcaval RFA was performed using an irrigated ablation catheter (Thermocool® SmartTouch Surround-Flow, Biosense Webster, Irwindale, CA) with power of 30W. RF delivery was turned off 3 seconds after a stable R-pattern change was seen on the unipolar EGM (Uni t+3). Inter-lesion spacing was directed by a 2nd operator, blinded to the electroanatomical map, and guided solely by Uni EGM morphology characteristic of viable myocardium as well as current of injury marking the contiguous location with ablated tissue (Figure 1A). Uni EGM signals were processed by the PureEP System (BioSig Technologies). Bidirectional block was demonstrated with standard EP maneuvers and histopathology. Uni EGM guided transcaval lines were compared to a historical cohort of ABi=400 guided transcaval lines. In 5 swine, transcaval ablation lines, guided by Uni EGM were performed. Bidirectional block was demonstrated in 4 of 5 lines (80%) and supported by postmortem histopathology (Figure 1B). Compared with transcaval lines with RFA guided by ABi, there was no difference in initial impedance, impendence drop, or mean length of the ablation line (Table). The Uni-t+3 lines were narrower (5.3±1.5mm vs 11.7±4.8mm, <0.001) and comprised of more closely spaced lesions (2.65±1.3mm vs. 3.4±0.5mm, p=0.001). RFA delivery time per lesion, guided by Uni-EGM modification, was substantially shorter (13.7±5.2sec vs. 21.9±5sec, p<0.001). While total RF delivery time did not differ between the groups [695sec (615-697) vs. 639sec (619-693), p=1). Monitoring changes in the local Uni EGM during ablation offers a real-time physiologic endpoint for titration of RF energy delivery. This study demonstrates that it is feasible to create a transmural line with bidirectional block using ablation that is guided by unipolar signals.Tabled 1Unipolar guided ablation lines Vs ABi linesParameterUt+3 LinesN=5Abi lines (control)N=4PImpedance (ohm)139±7.8131±8.50.3Impedance drop (ohm)14±6.816.1±5.10.1Ablation index333 (296-390)400<0.001Ablation time per lesion (sec)13.7±5.221.9±5<0.001Total RF time (sec)695 (615-697)639 (619-693)1Lesions per line49 (40-50)27 (26-31)0.01Inter-lesion distance (mm)2.65±1.33.4±0.50.001Line length (mm)70 (67-70)67 (66-75)0.62Line width (mm)5.3±1.5411.7±4.8<0.001Transmural80%100% Open table in a new tab