PMC4842360_01
(a) The left panel shows a 12-lead electrocardiogram (ECG) in sinus rhythm (SR) and the right panel shows that of atrial tachycardia (AT). (b) Intracardiac ECG during AT. T indicates the Halo catheter. Numbers 9-10 are the distal electrodes located at the lateral tricuspid annulus (TA). Numbers 19-20 are located at the anteroseptal TA. His 1-2 is the distal electrode of His. CS indicates the electrode catheter in the coronary sinus (CS). CS 1-2 is the distal electrode and CS 7-8 is located at the CS ostium. The dotted line indicates the earliest activity of AT recorded at CS 7-8.
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PP intervals. P wave morphology was bimodal, positive, and wide in leads I, II, III, and aVF and positive/negative in lead V1 (Figure 1(a)). The sinus rhythm ECG showed a different P wave morphology; lead I was flat, leads II, III, and aVF were positive, and lead V1 was positive/negative (Figure 1(a)). The earliest local activity was recorded at the CS ostium at this time (Figure 1(b)).
(a) The left atrial (LA) voltage map using a 3D electroanatomical mapping system. The grey area located at the anterior roof of the LA indicates the scar. The black circle indicates the site of entrainment pacing. The dotted line shows the linear ablation line between the LA scar and the ostium of the right upper pulmonary vein. (b) The LA activation map during AT. The arrowhead indicates local activity recorded around the scar. (c) Intracardiac ECG of the AT termination site recoded at the LA roof. ABL 1-2 indicates the distal electrode of the ablation catheter.
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Around the scar, there were low-voltage areas with fragmentation at the roof and right anterior wall of the LA (Figure 2(a)). This result indicated that the AT circulated around the scar in a counterclockwise fashion (Figure 2(b)). Entrainment pacing was performed at the LA roof (black circle in Figure 2(a)), where a fragmented potential was recorded (Figure 2(c)).
(a) Entrainment pacing at the LA roof with a stimulation interval of 290 ms slow conduction area as shown in Figure 2(a). The postpacing interval was the same as the AT cycle length. (b) The AT termination during the linear ablation.
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The postpacing interval was in accordance with the AT CL (Figure 3(a)). AT was finally terminated (Figure 3(b)). After completion of the ablation line, the AT could not be induced.