Biatrial Macroreentrant Tachycardia Involving Persistent Left Superior Vena Cava and Bachmann's Bundle

Figures

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  Visual Summary. Biatrial Macroreentrant Tachycardia Involving the PLSVC and BB (A) High-resolution activation mapping demonstrates a macroreentrant biatrial tachycardia incorporating 2 epicardial pathways: the PLSVC and BB. Entrainment pacing at the PLSVC, the RA septum, and the BB insertion site showed PPI–TCL differences of <30 milliseconds, supporting their critical participation in the reentrant circuit. (B) Detailed LA roof view showing the BB insertion at the anterior roof of the LA adjacent to a blocked anterior mitral line. BB = Bachmann's bundle; LA = left atrial; PLSVC = persistent left superior vena cava; PPI-TCL = postpacing interval–tachycardia cycle length; RA = right atrial.

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  Figure 1. Surface ECG Demonstrating Atrial Tachycardia Twelve-lead electrocardiogram (ECG) shows organized atrial activity with a 3:1 atrioventricular conduction.

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  Figure 2. Activation and Entrainment Mapping in the Left Atrium (A) Activation mapping indicated a blocked anterior mitral line, incomplete block across the mitral isthmus line, and the tachycardia cycle length could not be fully accounted for in the left atrium. The postpacing intervals were almost equal to the tachycardia cycle length at CS 1 and CS 2 (B), and CS 5 and CS 6 (C).

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  Figure 3. Prolongation of the Atrial Tachycardia by Ablation Along the Mitral Isthmus Line (A) Ablation at the pulmonary vein side of the mitral isthmus line did not alter the tachycardia cycle length, (B) whereas ablation at the annular side of the mitral isthmus line prolonged the tachycardia cycle length from 252 to 275 milliseconds.

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  Figure 4. Termination of the Atrial Tachycardia by Ablation Within the PLSVC Radiofrequency ablation targeting the connection of the left atrium and persistent left superior vena cava (PLSVC) resulted in immediate termination of the atrial tachycardia. Sinus arrest occurred, and temporary pacing was immediately initiated for cardiac protection.

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  Figure 5. Confirmation of Mitral Isthmus Block by LAA Pacing Pacing from the left atrial appendage (LAA) produced a proximal-to-distal activation sequence in the coronary sinus, indicating conduction block across the mitral isthmus line.