A Case of Roof‐Dependent Atrial Flutter With an Endocardial Narrow Channel Successfully Visualized by the Peak Frequency Analysis

Figures

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  FIGURE 1. (A) Catheter positions for the in situ recording of AT in fluoroscopic images. (B) Three‐dimensional voltage map of the LA acquired using the EnSite X system during the AT. A bipolar electrogram amplitude of < 0.5 mV was defined as low voltage, and sites with low voltage < 0.1 mV were designated as scarred areas. (C) A three‐dimensional activation map of the LA acquired using the EnSite X system during AT showing that it propagates from the upper to the lower part of the LA posterior wall. (D) Intracardiac electrogram recorded during AT with a cycle length (CL) of 256 ms. (E) Intracardiac electrogram recorded during pacing with a pacing CL of 245 ms at the distal tip of the ablation catheter (ABL), positioned in the LA posterior wall (indicated by the green tag in Figure 1B) during AT, entrained the tachycardia with concealed fusion and a post‐pacing interval of 262 ms (AT‐TCL + 6 ms). AT: Atrial tachycardia; LA: Left atrium; RA: Right atrium; CS: Coronary sinus; TA: Tricuspid annulus; LAO: Left anterior oblique; LSPV: Left superior pulmonary vein; LIPV: Left inferior pulmonary vein; RSPV: Right superior pulmonary vein; RIPV: Right inferior pulmonary vein; LAA: Left atrial…

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  FIGURE 2. (A) Three‐dimensional emphasis map combining voltage and peak frequency mapping (cut‐off: 200 Hz) during AT. (B) Emphasis map showing a narrow channel (indicated by the red dotted arrow) with high‐frequency sites in the LA posterior wall on the AT circuit, which was considered a breakthrough portion from the far‐field (subendocardial or epicardial) to the near‐field endocardial side. (C) AT was terminated by delivering radiofrequency energy at two points (red tag and termination yellow tag) covering this narrow channel by slowing the AT cycle length from 256 ms to 273 ms, and then to 284 ms. PF = peak frequency; RF = radiofrequency. Other abbreviations are as in Figure 1.

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  FIGURE 3. The PF value at the termination point (265 Hz, as shown in B) was higher than that at other local electrograms (as shown in A and C) in the LA posterior wall. The AT circuit considered from the PF value at the LA posterior wall was that propagation from LA roof to a narrow channel by the subendocardial or epicardial conduction (orange dotted line), the endocardial propagation between the high frequency area (white solid line), and again, the subendocardial or epicardial propagation to the LA bottom (orange dotted line) (shown by left panel). EGM = electrogram. Other abbreviations are as in Figures 1 and 2.