Regulation of RF-delivery under the temperature-control setting
As described above, regulation of RF-delivery under the temperature-control setting may impact both lesion characteristics and steam-pop events. We demonstrate in this study that this regulation was more frequently observed with the FlexAbilityTM SE catheter than the TactiCathTM SE catheter (60 [22%] vs. 4 [4%], p<0.001). Firstly, this may be due to the location of the thermocouple in determining the sensitivity to thermal change in the tissue during RF delivery. The location of the thermocouple is only 0.3 mm proximal to the tip in the FlexAbilityTM SE catheter, compared to 2.64mm in the TactiCathTM SE catheter. Our results compliment a previous study showing that the tip temperature of the FlexAbilityTM SE catheter provides better safety feedback compared to the ThermocoolTM and ThermoCool SFTM catheters, where the thermocouple is located 2.0mm and 6.6 mm from the distal end of the tip (16).
Termination of RF-delivery in the FlexAbilityTM SE catheter was more frequently observed with perpendicular catheter placement. This may be due to the localized temperature measurement capability of the catheter due to the distal placement and proximity to tissue of the thermocouple. When the catheter is placed parallel to the tissue, the kerfs direct irrigation flow towards the tissue surface thus enabling effective cooling of the tissue (16). However, when the catheter is placed perpendicularly, the irrigation flow spreads from proximal to distal, which may lead to relatively insufficient cooling (Figure 4, see supplemental VIDEO).