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.