Electrochemical potentials during radiofrequency energy delivery: a new method to control catheter ablation of arrhythmias

Aims Thermal injury of subendocardial tissue leads to a release of electrol ytes and free radicals from the intracellular site creating a change in ele ctrochemical potential (eP) between the distal and the proximal catheter ti p electrodes. The aim of the study was to verify the detection of ablation- induced release of electrolytes and free radicals and to assess the suitabi lity of control-line energy delivery at ablation by measuring eP. Methods and Results In vitro tests under constant flow conditions were perf ormed in a 101 bath of physiological saline solution or bovine blood. Endom yocardial preparations of fresh bovine hearts were used. Closed-loop temper ature-controlled, irrigated and closed-loop eP-controlled ablations were pe rformed. In vivo animal investigations were performed in six anaesthetized and ventilated Digs. The existence of the eP was established in the tank mo del and was confirmed in animal investigations. High correlations were foun d between eP and catheter tip temperature (r=087) and between maximum eP an d induced lesion size (r=0(.)85). Also a high correlation (r=0(.)85, P <0(. )001) was found between eP and lesion volume. Conclusions Control of energy delivery during RF ablation by the measuremen t of eP is feasible. In comparison with temperature controlled RF ablation, ablation guided by eP-measurement revealed a superior correlation with ind uced lesion size. Especially during cooled radiofrequency catheter ablation eP is the only parameter for control of energy delivery. (C) 2001 The Euro pean Society of Cardiology.