Real-Time Phase Mapping
In the same areas where the DF mapping was performed, mapping during AF
was simultaneously performed using an online real-time phase mapping
system (ExTRa MappingTM, Nihon Kohden Co., Tokyo, Japan) as described
previously.16 This mapping system was based on 41
bipolar intraatrial electrograms (including 9 virtual electrograms)
recorded by a deflectable 20-pole spiral-shaped catheter with a diameter
of 2.5 cm. The contact was confirmed by the recorded electrograms,
fluoroscopy, and 3D geometry. The distance between a mapping point and
the geometry surface created by the EnSite NavX was set at 5 mm. The
data sampling was adopted as good contact in areas where sufficient
electrograms could be recorded from the vast majority of the electrodes.
Based on the 5-s wave dynamics during AF, each phase map was
automatically created by ExTRa Mapping. Non-passively activated areas,
in which rotational activations were frequently observed, were
automatically detected by ExTRa Mapping. The value of the
“non-passively activated ratio” (%NP), which is the ratio of the form
of rotors and multiple wavelets assumed to contain AF drivers to the
recording time, was automatically calculated from the 5-s real-time
phase map created by ExTRa Mapping.16 Of the 5-s map,
the activation sequences during 720 ms (60 ms×12 consecutive time
windows) of representative episodes were depicted as images.