PMC9833369_01
(a) 12-lead electrocardiogram of atrial tachycardia (AT). It shows an irregular R-R interval, where heart rate varied from 140 to 150 bpm. The polarities of P wave from each lead are flat or unclear. (b) An electrogram showing AT with a cycle length of 262 ms. In both mapping catheters with 10 electrodes, the activation sequence shows slight proximal-to-distal conduction. (c) Cine angiography shows the ablation catheter, the mapping catheters, including the Advisor  HD grid mapping catheter, and thermometer. Two mapping catheters with 10 electrodes were placed in the coronary sinus and around the tricuspid annulus. LAO, left anterior oblique. (d) The bipolar voltage map during the AT. The low-voltage and scarred areas are defined as 0.05-1.0 mV and <0.05 mV, respectively. The scarred area is observed in the pulmonary veins and left atrial (LA) posterior area, and the low-voltage areas are identified in the LA bottom, and mitral isthmus areas. Pulmonary veins and LA posterior wall are completely isolated. AP, anteroposterior; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; PA, posteroanterior; RIPV, right inferior pulmonary vein; and RSPV, right superior pulmonary vein. (e) The activation map apparently indicates centrifugal pattern from LA infero-septal area (yellow arrows). The LA posterior area appears to act as obstructions in the tachycardia as well as the mitral isthmus line. The actual propagation of the tachycardia is considered to detour the epicardium of LA posterior area (yellow dotted arrow).
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At the end of the procedure, atrial tachycardia (AT) was induced by atrial burst pacing (pacing cycle length of 200 ms; Figure 1a,b). The two mapping catheters placed in the coronary sinus and around the tricuspid annulus indicated the proximal-to-distal sequence and the tachycardia cycle length of 262 ms (Figure 1b,c). The voltage map revealed scarred area in the LAPW (Figure 1d), while the activation map indicated a focal pattern wave front centrifugally propagated from the LA inferior or septal area to both atria (Figure 1e and Video S1).
(a) Post-pacing interval measured at the roof and bottom (blue points) at 265 and 268 ms, which closely matched tachycardia cycle length (262 ms). The tags represent ablation sites. The red, pink, and white tags show the lesion size index above 5.5, 4.0-5.5, and below 4.0, respectively. The yellow tags represent extra ablation for roof-dependent atrial flutter. AP, anteroposterior; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; PA, posteroanterior; RIPV, right inferior pulmonary vein; and RSPV, right superior pulmonary vein. (b) The second extra radiofrequency ablation (yellow tag) terminated roof-dependent atrial flutter. RF, radiofrequency.
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Post-pacing interval (PPI) was almost matched to the AT cycle length at the LA roof, bottom line that was near to the septal area (Figure 2a). Additional radiofrequency applications were delivered at the bottom line (Figure 2a, yellow tags). AT was terminated during the second application and became noninducible after final ablations (Figure 2b).