Breaking the Circuit: A Case of Macro-re-entrant Biatrial Tachycardia

Abstract

We present a case of a 71-year-old woman with symptomatic paroxysmal atrial fibrillation and atypical atrial flutter (AFL), ultimately diagnosed with a rare type 3 macro-re-entrant biatrial tachycardia (BiAT). Despite initial pulmonary vein isolation and anterior line ablation for atypical AFL, she experienced recurrent AFL requiring a complex redo ablation. Successful termination of the tachycardia was achieved by extending ablation to the septal regions of both atria. This case highlights the complexity of managing BiAT.

Keywords: Atrial fibrillation; atypical atrial flutter; catheter ablation; macro–re-entrant biatrial tachycardia.

Figure 1:

Atrial fibrillation with coarse waves.

Figure 2:

Anterior view of the left atrial voltage map after pulmonary vein isolation and anterior mitral annulus line. The first ablation procedure used a bipolar voltage map (0.05–0.5 mV) generated with a PentaRay^® mapping catheter (Biosense Webster). Complete pulmonary vein isolation was confirmed. An anterior line was created to target atypical atrial flutter, which was associated with scar in the anterior wall of the left atrium.

Figure 3:

Atypical atrial flutter after first ablation; atrioventricular 2:1 conduction, 115 bpm.

Figure 4:

Bipolar voltage and activation mapping of both atria during atrial tachycardia in the (A) anterior view and (B) posterior view. The left panels show activation maps encompassing the entire tachycardia cycle length (280 ms) across both atria. The right panels show bipolar voltage maps with settings of 0.05–0.5 mV, demonstrating normal and low-voltage areas.

Figure 5:

A: Septal left atrial entrainment by OCTARAY™ mapping catheter electrode E3–4 showed post-pacing interval (280 ms) – tachycardia cycle length (280 ms) = 0 ms (sweep speed, 150 mm/s). B: Septal right atrial entrainment by ablation catheter showed a post-pacing interval−tachycardia cycle length of 0 ms (sweep speed, 100 mm/s).

Figure 6:

Activation map during tachycardia (cycle length, 280 ms) of both atria. The activation map demonstrates complete tachycardia cycle mapping in both atria, with the earliest activation near the anterior right upper pulmonary vein, likely due to prior anterior mitral isthmus line ablation. Entrainment mapping confirmed out-of-circuit sites (gray dots) and circuit sites (white dots). The circuit involved the septa of both atria (green arrows). Successful ablation was achieved at the right posterior septal right atrium (star marker).

Figure 7:

Tachycardia termination during catheter ablation on the septal right atrium (sweep speed, 150 mm/s).