Electrogram analysis
By using fast Fourier transform
analysis, Pachon et al (63) definedcompact andfibrillar atrial potentials during sinus rhythm. Because
fibrillar potentials demonstrated fragmented and heterogeneous
conduction properties, authors speculated that fibrillar potentials may
be originated from incursions of neural and vascular structures and be
used to detect autonomic innervation
sites. Lellouche et al (64)
analyzed electrogram characteristics based on VRs during radiofrequency
application and demonstrated that the best single predictor of VR during
radiofrequency application was the presence of at least 4 electrogram
deflections at the ablation site. In our initial work, epicardiac
ganglia sites were detected through a combination of fast Fourier
transform analysis of electrograms, and HFS (65). In accordance with
Lellouche’s observations, all the electrograms on the radiofrequency
ablation sites demonstrated a fragmented pattern. Because the better
resolution afforded by usage of higher high-pass filters allowed better
appreciation of electrogram fragmentation (63), in our subsequent work,
we used band-pass filter settings of 200-500Hz instead of conventional
band-pass filter settings of 30-500Hz during sinus rhythm and targeted
all fragmented electrograms in regions which are anatomically consistent
with autonomic innervation sites (46) (Table 1). Indeed, this simpler
electroanatomical mapping-guided strategy demonstrated an identical
success rate in preventing prodromal symptoms and syncope recurrence as
compared to the previous combined approach. Figure 5 demonstratesthe
anatomical distribution of GPs according to our definition method (49).