RELATION BETWEEN IMPEDANCE AND ELECTRODE TEMPERATURE DURING RADIOFREQUENCY CATHETER ABLATION OF ACCESSORY PATHWAYS AND ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

Objectives Impedance monitoring has been proposed as a method to asses s the adequacy of tissue heating during catheter ablation procedures. The purpose of this study was to evaluate the relation among initial i mpedance, Fall in impedance, and electrode temperature during catheter ablation procedures. Methods and Results Data from 248 applications o f radiofrequency energy in 45 consecutive patients (26 with accessory pathways and 19 with atrioventricular nodal reentrant tachycardia) ref erred for catheter ablation were analyzed. The initial impedance was h igher during ablation of accessory pathways than during atrioventricul ar nodal reentrant tachycardia (116 +/- 66 versus 106 +/- 80 Omega, P < .001). In both groups, a significant correlation was observed betwee n the initial impedance and temperature (R = 0.98, P < .001). After ac counting for differences between patients and ablation targets, an eve n closer correlation was observed (accessory pathways: R = 0.95, P < . 0001; atrioventricular nodal reentrant tachycardia: R = 0.94, P < .000 1). Conclusion These data suggest that monitoring of the initial imped ance and the fall in impedance during ablation procedures may provide clinically valuable information to assess the efficacy of tissue heati ng and lesion formation.