Role of electrograms recorded from mini electrodes in catheter ablation of atrioventricular nodal reentrant tachycardia: a retrospective study

Figures

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  Fig. 1. Ablation catheter used for mapping and ablation. A The IntellaTip MiFi open-irrigated ablation catheter (Boston Scientific, Boston, MA, USA) has three mini electrodes (MEs) at the tip of the catheter, which are 1.3 mm distant from the tip of the catheter. This 7.5-Fr ablation catheter has a 4.5-mm-sized tip electrode and three ring electrodes. B The MEs (marked with arrowheads), surrounded by an insulating ring, are positioned radially with the same inter-electrode distance. A schematic image demonstrating the location of the MEs (displayed with three gray-colored small rounds) of the ablation catheter distal tip is inserted in the right upper corner

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  Fig. 2. Representative cases with and without atrial electrograms in mini electrodes. Mini electrode (mini 12, 23, and 31) electrograms (EGMs) of four patients immediately before the first radiofrequency ablation. In the first three patients (A–C), atrial EGMs on the mini electrodes (MEs) were observed, whereas none was detected in the fourth patient (D). An inducible junctional rhythm was observed in the first three patients, but not in the fourth patient. In the first two patients (A, B), the atrial EGM of MEs demonstrated a double component, which was an initial low-frequency, low-amplitude component, followed by a high-frequency, high-amplitude component. The pattern of the double component is only evident in MEs and is not definite in bipolar electrodes (BEs), as demonstrated in panel (B). In the next patient (C), a high-frequency component followed by a low-frequency pattern was observed in the MEs and BEs. Panel D presents the case with good BE EGMs but without definite atrial EGM in the MEs. Only small (<0.05 mV) and delayed noise-like EGMs were visible in the ME, demonstrating a discrepancy between BE and ME. The gain settings of the MEs were the same, and the sweep speed was…

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  Fig. 3. Dot plots with box plot overlays presenting voltage of mini-electrode bipolar electrogram. The amplitudes of mini-electrode (ME) electrogram (EGM) before the first radiofrequency application were compared. The mean amplitude values are 0.19 ± 0.11 mV and 0.11 ± 0.06 mV in the case with and without inducible junctional rhythm, respectively. The amplitude of the ME EGM was significantly different between the groups (P = 0.035). Each dot represents a single patient’s voltage in the EGM. Solid line = median