TEMPERATURE MONITORING DURING RADIOFREQUENCY CATHETER ABLATION PROCEDURES USING CLOSED-LOOP CONTROL

Background The purpose of this study was to evaluate electrode tempera tures obtained using a radiofrequency ablation system that incorporate s closed loop feedback control to achieve preset target electrode temp eratures and to determine if closed loop temperature control results i n a lower incidence of developing a coagulum. Methods and Results Two hundred seventy patients underwent catheter ablation of atrioventricul ar nodal reentrant tachycardia, an accessory pathway, and/or the atrio ventricular junction using an ablation system incorporating closed loo p feedback control. Forty-five patients underwent catheter ablation in the power control mode in which power output was fixed, and 225 patie nts underwent catheter ablation in the temperature control mode. A coa gulum occurred during 0.8% of radiofrequency applications in the tempe rature control mode versus 2.2% in the power control mode (P<.01). Ele ctrode temperatures were within 10 degrees C of the targeted temperatu re during 35% of applications in the temperature control mode. Ability to achieve the targeted electrode temperature was related to the targ et, with radiofrequency energy applications at the atrioventricular ju nction resulting in the highest temperatures (70+/-12 degrees C) and t hose for ablation of the atrioventricular node the lowest (59+/-11 deg rees C, P<.001), using a maximum of 50 W of power for both. Electrode temperatures were higher during ablation of left free wall and postero septal pathways than during ablation of right free wall and septal pat hways. The mean and minimum temperatures associated with success were 64+/-12 degrees C and 44 degrees C, respectively. Overall, the electro de temperatures at successful and unsuccessful ablation sites did not differ (P>.05). Conclusions Temperature monitoring with closed loop co ntrol of power output facilitates radiofrequency catheter ablation pro cedures by minimizing the probability of developing a coagulum while e nsuring maximum lesion formation.