Use of a software to map ganglionated plexus sites
Despite promising results with the visual electrogram-guided GP ablation strategy, there are concerns regarding reproducibility of this technique, especially amongst relatively inexperienced operators. In this regard auto-algorithm software identifying fractionated areas may aid in developing more careful mapping to localize GPs. The Ensite PrecisionTM (Abbott) system includes the fractionation mapping software that provides an algorithm to detected fragmented areas. Although there is some similarity with the CFAE (complex fractionated atrial electrogram) settings, the cycle length of atrial fibrillation is not taken into account in this new software. Fractionation mapping software was first used to detect critical ablation sites during sinus rhythm in a patient with vagal atrial fibrillation by our group (30). Mapping parameters were standardized at internal and external projections of 7 mm, interpolation of 7 mm, low-voltage identification of 0.1 mV. The Inquiry™ AFocusII™ (Abbott) catheter with 4-mm electrode spacing collected fractionated signals over 5 s. A baseline noise threshold of 0.05 mV was applied to exclude background system noise. Fractionation map was created using possible combinations of width (5 msec), refractory time (30 mses), and roving sensitivity (0.1 mV). Based on these parameters, the algorithm assigned each electrogram a fractionation score. The map color scale was set to color areas at or above the defined fractionation threshold as white (suggestive of fractionated electrogram) and below as purple (suggestive of nonfractionated electrogram). Acute atrial fibrillation termination was achieved during ablation in the fractionated areas (white) around the superior right atrial GP site. We have also reported this technique during sinus rhythm (31). The map color scale was set to color areas at or above the fractionation threshold of 2 as white. White areas were accepted as potential GP sites and were compared areas which were visually detected by our fragmented electrogram-guided method. Distribution of white areas demonstrated a close similarity with ablation points that were detected using visual fragmented EGM-based strategy (Figure 4). In our cases, ablation catheters (FlexAbility®, Abbott) were used for mapping. Other groups have demonstrated similar procedural results with Virtual/remote real-time proctoring during the case by high-density mapping catheters (32, 33). However, the technique is still not validated in larger patient groups and multicenter studies are needed to confirm this benefit.