Left atrial dual-loop reentry with endocardial and epicardial conduction pathway

Figures

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  Figure 1. A: The electrograms during atrial tachycardia showing 2:1 atrioventricular conduction. The mapping catheters placed in the coronary sinus (CS) and at the tricuspid annulus (TA) exhibit a proximal-to-distal sequence (indicated by black arrows) with a cycle length of 232 milliseconds. B: The bipolar voltage map obtained during atrial tachycardia, combined with computed tomography (CT) scan data, shows low-voltage and scarred areas in the left atrial anterior wall, the isolated pulmonary veins, and the isolated posterior wall. Low-voltage and scarred areas are defined as 0.05−0.5 mV and <0.05 mV, respectively. C: The activation map clearly indicates mitral annular flutter (shown by a solid yellow arrow), but also shows a wavefront spreading centrifugally from the inferior area of the left atrium (shown by dotted yellow arrows). White areas are simultaneously observed in the inferior and anteroseptal regions. The map is not combined with CT scan data because it includes the geometry of the CS and the vein of Marshall (VOM), which are not part of the CT imaging. D: The electrograms of the VOM exhibit a reverse dogleg sequence (indicated by solid and dotted arrows), and the…

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  Figure 2. A: Entrainment pacing from the distal vein of Marshall (VOM) shows a postpacing interval of 233 milliseconds, corresponding to the tachycardia cycle length. The pacing also exhibits orthodromic capture (indicated by black arrows) in the coronary sinus (CS) and the left atrial inferior region, which is the earliest activation site (recorded by the Advisor HD Grid Mapping Catheter; Abbott, Chicago, IL). In addition, the sequences observed in both the CS and the earliest activation site are nearly identical during both pacing and tachycardia. B: The location of the mapping catheters during entrainment pacing. C: Proposed circuits of the dual-loop reentry. Mitral annular flutter follows an endocardial pathway (indicated by the solid yellow arrow), and the other reentry partially follows an epicardium pathway (indicated by the dotted yellow arrow), including the coronary sinus and the distal VOM, and breaks through to the endocardium from the left atrial inferior region. Wavefronts traveling up and down the VOM converge and conflict at this location. D: The 3-dimensional (3D) maps represent activation vectors and color at the earliest activation site, as recorded and monitored by the…

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  Figure 3. A: The electrograms of the coronary sinus (CS) and vein of Marshall (VOM) after ethanol ablation, showing a proximal-to-distal sequence (indicated by black arrows). Far-field potentials are recorded in the VOM. B: The activation map clearly indicates a simple mitral annular flutter (shown by yellow arrows). C: Termination of mitral annular flutter and restoration of sinus rhythm after a 1-second interval. The electrograms recorded by CS 3–4, VOM 1–2, and VOM 3–4, which are located on the mitral isthmus line, are significantly reduced during radiofrequency ablation. D: The 3-dimensional map shows ablation points for mitral annular flutter. Red tags represent ablation durations of more than 20 seconds and the yellow tag indicates a successful point in terminating the mitral annular flutter. AP = anteroposterior; LAA = left atrial appendage; LPV = left pulmonary vein; PA = posteroanterior; RPV = right pulmonary vein.