Ablation catheter and local impedance measurements
An open-irrigated MiFi ablation catheter with a 4.5 mm distal tip and an open-irrigated STABLEPOINT ablation catheter with a 4.0 mm distal tip were used for the experiment. The MiFi has 3 microelectrodes incorporated within the distal tip electrode, and there are 3 equally spaced 0.8 mm diameter microelectrodes located 2 mm from the tip of the catheter. First, LI was measured between each microelectrode and the 4th ring electrode of the ablation catheter by a driven nonstimulatory alternating current (5.0 𝜇A, 14.5 kHz) between the distal tip electrode and the 4th ring electrode to create a local potential field. After that, only the maximum LI was selected for the actual LI. Since the CF cannot be measured in the MiFi catheter, it was measured using the pressure-current transducer (load cell), as described in the next section. On the other hand, the STABLEPOINT does not have microelectrodes, and the LI was measured between the whole distal tip (4 mm length) and 2ndring electrodes by being driven by a nonstimulatory alternating current (5.0 𝜇A, 14.5 kHz) between the distal tip electrode and the 4th ring electrode to create a local potential field.