Temperature-controlled radiofrequency catheter ablation of manifest accessory pathways

Objectives The primary objectives of this study were to assess the feasibility of temperature-controlled radiofrequency catheter ablation of left and right sided manifest accessory pathways in patients with Wolff-Parkinson-White syndrome and to gain more insights into biophysical aspects of temperature-controlled catheter ablation in humans. Background The electrode-tissue interface temperature and other biophysical parameters are among important variables determining the efficacy and safety of radiofrequency ablation of accessory pathways. Experimental studies have shown that radiofrequency-induced tissue necrosis can be accurately predicted by monitoring of catheter tip temperature. Methods 38 consecutive patients (14 f, 24 m; aged 42 ± 12 years) with anterograde conducting accessory pathways (left sided: n=22; right sided: n=l6) underwent temperature-controlled radiofrequency ablation (HAT 200S, Dr Osypka, Germany). The electrode temperature was monitored via a thermistor embedded into a 4 mm catheter tip. Power output was adjusted automatically during energy delivery in a closed loop system (preselected temp.: 70·1 ± 5·8°C). Results Accessory pathway conduction was successfully abolished in all patients after the delivery of 2·3 ± 2·1 radiofrequency pulses (range: 1–9, median: 2). Interruption of the accessory pathway as evidenced by loss of preexcita tion occurred after 5·9 ± 5·4 s. At the time of the interruption of the accessory pathway the catheter tip temperature measured 54·2 ± 11· 2 ° C in patients with left and 44·9 ± 5·0° C in patients with right sided accessory pathways, respectively ( P