Localized atrial fibrillation within the inferior sinus venosa treated by isolation: Could it be a new target of ablation for persistent atrial fibrillation?

Figure 1. Twelve-lead electrocardiogram and computed tomography image before atrial fibrillation ablation. A: A 12-lead electrocardiogram of sinus rhythm and atrial premature contraction in a patient with recurrent atrial fibrillation after the first session of catheter ablation. atrial premature contraction exhibited negative P waves in the inferior leads, isoelectric P waves in lead I, and positive P waves in lead V1. B: Axial view of the cardiac computed tomography before ablation.

Figure 2. Three-dimensional mapping and intracardiac electrogram expressing that localized atrial fibrillation (AF) was observed only within the inferior sinus venosa (SV). A: Complex fractionated electrogram mean diagnostic landmark mapping (EnSite system) of RA showing that localized AF was observed only within the inferior SV. Complex fractionated electrogram mean was the average time interval between consecutive deflections over 5 seconds. A mean cycle length of < 500 ms was considered to represent AF, as the sinus rate was 60 beats per minute. Localized AF was observed only within the inferior SV, whereas other areas of the RA showed sinus rhythm. Green tag, first ablation point (fossa ovalis); yellow tag, second ablation point (upper side of the inferior SV); red tag, AF termination point. B: Intracardiac electrogram. The ablation of the upper part of the inferior SV (Figure 1A, red tag) converted AF to sinus rhythm. C: Intracardiac electrogram. Localized AF was maintained only within the inferior SV, whereas the other areas of the atrium showed sinus rhythm. ABL = ablation;; CS = coronary sinus; IVC = inferior vena cava; LA = left atrium; RA = right atrium; SVC = superior vena cava.

Figure 3. Low-voltage area and arrhythmogenicity of the inferior sinus venosa (SV). A: High-density voltage mapping of the right atrium (RA) during sinus rhythm. The low-voltage area in the RA during sinus rhythm was defined as a bipolar voltage of <0.5 mV. B: Intracardiac electrogram. Automatic electrical activity (red circle) inside the isolated inferior SV was observed. C: Intracardiac electrogram. Rapid atrial pacing (50 ms/30 mA) at the isolated inferior SV induced localized AF. The colored tags have the same settings as in Figure 1. ABL = ablation; CS = coronary sinus; IVC = inferior vena cava; LA = left atrium; RA = right atrium; SVC = superior vena cava.