Expect the unexpected: Ablation of an atypically located atrial tachycardia

Figures

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  Figure 1. A: Three-dimensional reconstruction of the right atrium. Yellow dots indicate the sinus node exit during sinus rhythm, white dots the course of phrenic nerve, blue dots the bundle of His, and green dots the earliest activation recorded on the lasso catheter during tachycardia. B: Cardiac tracing. Early activation with remote signals detected on the circular catheter (red arrow) in the superior vena cava ostium. On the ablation catheter positioned in the right atrial appendage pouch, local signals with a comparable timing to the far-field signals can be appreciated. C: Three-dimensional reconstruction of the right atrium after the pouch of right atrial appendage is identified. Red dots indicate sites of ablation. Ablation inside the pouch terminated the atrial tachycardia. D: Angiography in right anterior oblique view reveals the right atrial appendage pouch (white arrow). The lasso catheter is positioned in the superior vena cava. CS = coronary sinus; His = bundle of His; HRA = high right atrium; LAS = decapolar circular catheter; MAP = ablation catheter; RAA = right atrial appendage; RVa = right ventricular apex; SN = sinus node.

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  Figure 2. Cardiac tracing (upper panel) showing termination of atrial tachycardia (AT) during ablation with conversion to sinus rhythm and matching visual explanation (lower panel) of the difference in activation sequence of the last AT complex (A) and the first sinus rhythm complex (B). As appreciated, during AT the far-field signals on the circular catheter (dashed square) are the earliest detected signals, indicating that the origin of AT is in the right atrial appendage (RAA) pouch. During sinus rhythm, the RAA pouch is activated later, as shown in panel B. Upper panel: HRA = high right atrium; LAS = decapolar circular catheter; MAP = ablation catheter; RVa = right ventricular apex. Lower panel. Lasso = decapolar circular catheter in the superior vena cava; RAA = diagnostic catheter in the right atrial appendage; RVa = diagnostic catheter placed in the right ventricle.