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).