Atrioventricular Nodal Reentrant Tachycardia Ablation Using Mini-Electrode Recordings

Figures

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  Figure 1. Catheter used for mapping and radiofrequency ablation (IntellaTip Micro Fidelity Open Irrigated MiFi OI, Boston Scientific, Boston, MA, USA). The three insulated mini-electrodes are radially arranged directly on the radiofrequency-delivering 4.5 mm irrigated distal tip. Bipolar recordings are performed between electrodes 1–2, 2–3 and 3–1.

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  Figure 2. Tracings in 5 patients. (1A–3A) Sharp potential as described by Jackman and colleagues can be easily identified before ablation on the mini-electrodes bipolar channels, and on distal ablation bipole in 1 patient (2A) (red arrows); (1B–3B) post-ablation double potentials can be visualized (orange arrows). (4) Discrete low dV/dt potential as described by Haissaguerre and colleagues before ablation (4A), and post-ablation double potentials (4B) (orange arrows). (5) Haissaguerre slow pathway potential before ablation in sinus rhythm (5A) and during atrial pacing (5B), and post-ablation double potentials (5C) (orange arrows). V1: precordial surface lead V1; d and p, ablation catheter distal (1–2) and proximal (3–4) bipolar recordings, respectively; 1–2, 2–3, and 3–4, bipolar channels between corresponding mini-electrodes.

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  Figure 3. Tracings in patient #11 following successful ablation of the slow pathway. Double potentials can be easily identified on the mini-electrodes bipolar channels (ME 2–3 and 3–1), not on the distal ablation conventional bipolar tracing (ABL D). From left to right, with an atrial extra-stimulus coupling interval of 500, 480, 460 and 440 ms, the delay between sharp and slow potential (orange arrows) progressively increases from 114 to 180 ms, until it is hidden into the ventricular farfield potential.

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  Figure 4. Tracings in patient #7 before and during radiofrequency application. (A) Just before ablation, in sinus rhythm, consistent stable double potentials are visualized (separation delay 58 ms) on the mini-electrodes bipolar channels (MIFI 1 2, 2 3, and 3 1) in the slow pathway area; (B,C) after 1 s (B) and 6 s (C) of radiofrequency application (30 W), an incremental double potential interval can be monitored on the insulated mini-electrodes recordings (74 and 94 ms), while the conventional distal ablation channel is completely oversaturated with noise (ABL D).

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  Figure 5. Schematic view of Koch triangle, prior (A) and following (B) ablation of the slow pathway proposing an explanation of double potentials visualization. During ablation, gradual split of the so-called slow pathway potential (A), leading to a double potential can be observed on the ablation line (B). The first potential (1) might represent the anterograde activation through the proximal portion of the slow pathway, below the ablation line, while the second potential may represent the late retrograde activation of the distal part of the slow pathway, above the line. FP: fast atrioventricular nodal pathway; SP: slow atrioventricular nodal pathway; CS: coronary sinus ostium; TT: tendon of Todaro; TA: tricuspid annulus; AVN: atrioventricular node; HB: His bundle.