Role of catheter location on local impedance measurements and clinical outcome with the new direct sense technology in cardiac ablation procedures

Figures

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  Fig. 1. A. Three-dimensional electroanatomical activation map of left atrial flutter, depicting the ablation catheter at the anterior wall. Red inlay: After identifying a suitable ablation location at the isthmus of the macro re-entrant tachycardia with tactilely good tissue contact according to a high start impedance (120 Ohm, grey bar) we observed an excellent local impedance drop of 20 Ohm (2nd yellow-highlighted bar) during RF delivery. Stimulation via the proximal CS-catheter was performed for extensive sinus bradycardia after arrhythmia termination. The ventricular response to the 4th atrial stimulus is blanked due to the ongoing electrocardiogram renewing in real time during the procedure. The white and yellow lines depict the real-time LI and the averaged LI over time (red box), respectively, with variation for cardiac and respiratory cycles. B. An alternating current of a fixed magnitude is sent through the tip electrode and the proximal ring. The resulting electrical field potential is measured between the distal ring and each individual mini electrode. The local impedance can be calculated based on the measured voltage and the injected current. C. The equipotential surfaces…

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  Fig. 2. Blood pool values for local impedance in the four cardiac chambers, suggesting no significant difference in the intergroup comparison (p = 0.91). LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

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  Fig. 3. A. Comparison of baseline local and global baseline impedance, demonstrating significant difference in all four cardiac chambers. B. Local impedance (LI) measures after established tissue contact before RF delivery within the four cardiac chambers with pairwise comparison, with the lowest LI values in the LV and RA. C. Comparison of the local and global impedance drop, suggesting a significant difference in the four assessed chambers, with the highest proportional difference in the RV. Abbreviations as in Fig. 2.

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  Fig. 4. Moderate positive correlation of local impedance and corresponding impedance drop (R2 = 0.26), with the best correlation in the RV, with a R2 of 0.31 (p < 0.01). B. Fig. 4B showing the correlation of global impedance and corresponding impedance drop suggesting no relation between the two measures.

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  Fig. 5. Mid-term outcome in the AF cohort (first PVI, no re-dos) comparing procedures performed with the direct sense system (DS) compared to a historic control (CTL group). No significant difference with respect to clinical outcome could be observed between the two groups. AF, atrial fibrillation; PVI, pulmonary vein isolation;.