LI measurements
An electric field was created by altering the current (5.0 micro-A at 14.5 KHz) between each tip of the three miniature electrodes and the proximal ring of the ablation catheter (Figure 2). Voltage was measured between the miniature electrodes and the distal ring. Impedance was calculated by dividing the voltage by the stimulatory current. Among three impedance measurements from the three miniature electrodes, the highest impedance was used as the LI. LI measurements were defined as follows: pre-RFA LI, LI just before the start of RFA; post-RFA LI, LI just after the end of RFA; LI drop, post-RFA LI – pre-RFA LI.
During the procedure, the operator was blinded to LI information. Dedicated medical engineers recorded the pre- and post-RFA LI and GI at each ablation point.