Characteristics of the Arrhythmogenic Substrate and the
Potential FCB Region
ATs in 7 of 8 originating patients were associated with the presence of
one or more scars. The electrical activity in scar areas always showed
DPs, FPs or ESAs. Some scars
formed a spontaneous conduction block line or perhaps slow conduction.
In these serial cases, we found that some spontaneous lines were not
constantly blocked, and some were exhibited only in one AT, which
suggests that the conduction characteristics in this region were changed
depending on the different mechanisms of ATs (Figs. 1-3). Five of these
8 patients exhibited these
potential FCBs, and all of these
FCB areas seemed to be near the scar areas. The presentation of the FCB
region was not related to the CL of ATs or the mechanism of ATs. The
potential of these regions could also be converted between DPs, FPs and
normal potential (but showed low amplitude in some cases) due to the
different ATs. Three of the others did not show potential FCBs, two were
focal mechanisms, and the other one was a double-loop localized reentry,
which was performed using a protected channel between an anterior line
of DP and an anterior ESA (Fig. 4). ATs maintained by the FCB region are
common in localized reentrant ATs. The FCB region was related to damage
to the previous ablation line in one patient. The voltage maps of 2
patients were performed during sinus rhythm after ablation, and the
potential of the FCB area presented no obvious difference from the
adjacent normal area.