Conduction Gap of Left Atrial Anterior Wall Linear Ablation Undetected by Left Atrial Appendage Pacing but Revealed by Left Lateral Ridge Pacing

Figures

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  FIGURE 1. (A, B) Pre‐ablation computed tomography images. (C, D) High‐resolution left atrial voltage map during right atrial appendage pacing. AP, anterior–posterior; CS, coronary sinus; LAA, left atrial appendage; LAO, left anterior oblique; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; MA, mitral annulus.

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  FIGURE 2. (A) An AT induced by burst pacing from the proximal CS, showing a distal‐to‐proximal CS activation sequence. (B, C) High‐resolution left atrial activation map during the AT showing an apparent focal activation pattern with a breakthrough from the inferior edge of the LLR and subsequent ascent through the isthmus between the transseptal incision line and the LAA resection line. The estimated conduction velocity along the 3D shell from the superior edge of the LLR to the breakthrough site at the inferior edge of the LLR was 43.44 mm/118 ms = 0.37 m/s. (D) Ablation points of the LAAW line, including the AT termination site near the LLR. AT, atrial tachycardia; LAAW line, left atrial anterior wall linear lesion; LLR, left lateral ridge; MB, Marshall bundle; SVC, superior vena cava; d, distal; p, proximal. Other abbreviations are as in Figure 1.

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  FIGURE 3. (A) Validation map of the LAAW line during pacing from the residual LAA stump showing apparent conduction block across the LAAW line. (B) Validation map during pacing from the LLR showing a conduction gap with breakthrough near the superior edge of the LLR. The estimated conduction velocity along the 3D shell from the pacing site to the breakthrough site was 23.3 mm/49 ms = 0.48 m/s. Abbreviations are as in Figures 1 and 2.

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  FIGURE 4. Possible mechanism of the gap conduction observed during LLR pacing. (A) During pacing from the LAA, clockwise endocardial conduction around the mitral annulus reaches the left atrial anterior wall earlier than the delayed counterclockwise wavefront. (B) During pacing from the LLR, direct capture of the MB unmasks residual counterclockwise epicardial conduction across the LAAW line. RSPV, right superior pulmonary vein. Other abbreviations are as in Figures 1, 2, 3.