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.