High‐Resolution Mapping and Ablation of Atrial Tachycardias Involving the Lateral Left Atrium

Figures

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  Figure 1. A representative case of peri‐mitral AT (A) and focal AT originating from the posterolateral MI (B). A, An activation map revealed a clockwise peri‐mitral AT with an endocardial conduction gap located below LIPV (asterisk) in the prior MI linear lesion. The AT was terminated by a single radiofrequency application in the gap. A voltage map showed a low‐voltage area in the previous MI linear lesion. B, An activation map revealed a focal AT originating from the posterolateral MI (white star) behind the previously created complete MI block line. Left atrial activation time accounted for only 30% of the TCL. The AT was terminated by focal ablation at the earliest local activation site (white star). The white arrows show the propagation of the activation. AT indicates atrial tachycardia; Bi, bipolar; CS, coronary sinus; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; LAA, left atrial appendage; MI, mitral isthmus; PPI, post pacing interval; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein; TCL, tachycardia cycle length; and Uni, unipolar.

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  Figure 2. Two representative cases (A and B) of small reentrant AT in the posterolateral MI. Activation maps revealed a small reentrant circuit in a counter‐clockwise fashion in the posterolateral MI. A macroreentrant AT was ruled out by entrainment pacing. An area with slow conduction and low‐amplitude fractionated signals was identified below the LIPV (asterisks). ATs were terminated by a single application at the site. Both patients had a history of previous MI area ablation and low‐voltage areas were identified on the voltage maps. AT indicates atrial tachycardia; Bi, bipolar; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; LAA, left atrial appendage; MA, mitral annulus; MI, mitral isthmus; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein; TCL, tachycardia cycle length; and Uni, unipolar.

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  Figure 3. A representative case of left atrial ridge–related AT (A) and micro‐reentry in the left atrial ridge (B). A, An activation map revealed left atrial ridge–related AT with upward activation in the ridge. The patient had a history of MI linear ablation. The critical isthmus was identified at the ridge‐LA junction (exit from the ridge) (asterisk), and a single application terminated the AT. Subsequently, ridge‐LA conduction block was confirmed. B, An activation map revealed micro‐reentry (localized reentry) within the left atrial ridge, and activation of a small area (asterisk) accounted for the entire TCL. The patient had no history of ablation. A single application terminated the AT. Bi indicates bipolar; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; MA, mitral annulus; PPI, post pacing interval; RSPV, right superior pulmonary vein; TCL, tachycardia cycle length; and Uni, unipolar.

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  Figure 4. A representative case of MB‐related AT. A, An activation map revealed MB‐related AT with downward activation in the VOM. Slow conduction (asterisk) was identified at the LA‐MB junction (entrance of MB), and a single application at the site terminated the AT. B, Following venography, a 1.8‐Fr hexapolar catheter was inserted into the VOM to validate the MB‐related AT (left panel). Pacing from the LAA (ablation catheter) showed proximal‐to‐distal VOM activation (right panel), suggesting LA‐MB conduction block. C, Differential pacing from the proximal and distal VOM electrodes showed longer LAA delay during distal VOM pacing, suggesting MB‐LA conduction block (lower panel). An activation map during pacing from the VOM showed MB‐LA conduction block, indicating bidirectional MB‐LA conduction block at the junction (upper panel). AP, antero‐posterior; Bi, bipolar; CS, coronary sinus; d, distal; LAA, left atrial appendage; LAO, left anterior oblique; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; p, proximal; PPI, post pacing interval; RSPV, right superior pulmonary vein; TCL, tachycardia cycle length; Uni, unipolar; and VOM, vein of Marshall.

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  Figure 5. A representative case of MB‐related AT with the critical isthmus in the left atrial ridge (A) and a left atrial ridge–related AT where the critical isthmus was not in the left atrial ridge (B). A, An activation map revealed dual‐loop MB‐related AT with downward activation in the MB. The common isthmus (asterisk) was identified at the LA‐MB junction (entrance of MB), and ablation at the site terminated the AT (left panels). Following venography, a 1.8‐Fr hexapolar catheter was inserted into the VOM to validate the MB‐related AT (right panels). Yellow and red arrowheads indicate the VOM and great cardiac vein, respectively. B, An activation map revealed left atrial ridge–related AT; however, the critical isthmus was identified at the roof of the left atrium, inside a scar. A single application at the isthmus terminated the AT. AT indicates atrial tachycardia; Bi, bipolar; CS, coronary sinus; GCV, great cardiac vein; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; MB, Marshall bundle; PPI, post pacing interval; RAO, right anterior oblique view; RSPV, right superior pulmonary vein; and VOM, vein of Marshall.

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  Figure 6. A representative case of PLSVC‐related AT. A, An activation map revealed PLSVC‐related AT with downward activation in the PLSVC (left panel). Activation of PLSVC alone showed a focal pattern (asterisk) from the LA‐PLSVC junction (right panel). Focal ablation at the site from the PLSVC side terminated the AT. B, Venography showed the PLSVC on fluoroscopy. The activation pattern inside the PLSVC during LAA pacing abruptly changed from distal‐to‐proximal to proximal‐to‐distal with additional ablation at the LA‐PLSVC junction, suggesting LA‐PLSVC conduction block at the junction. C, Subsequently, PLSVC pacing showed PLSVC‐LA conduction block, indicating bidirectional conduction block at the LA‐PLSVC junction. AP, antero‐posterior; AT, atrial tachycardia; d, distal; LA, left atrium; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; MA, mitral annulus; p, proximal; PLSVC, persistent left superior vena cava; and PPI, post pacing interval.