Introduction and objectives: The Stereotaxis(R) remote magnetic navigation system provides a new approach to ablation that could increase catheter stability. The aim was to determine whether improved tissue contact necessitates a change in traditional radiofrequency ablation parameters.
Methods: The study compared ablation of atrioventricular nodal reentrant tachycardia (AVNRT) using remote navigation (4-mm catheter) in 19 patients with conventional ablation in 18 patients (4-mm catheter, temperature 60-65 degrees C, power 50 W). The radiofrequency energy needed to ensure that no more than a single nodal echo beat could be induced was measured.
Results: Charring was observed with traditional parameters on the first applications of the remotely navigated catheter. Hence, the energy was subsequently reduced (to 50 degrees C and 40 W). There was no difference in the number of applications between remote navigation and conventional groups (median: 6 vs. 8.5; interquartile range [IQR]: 11 vs. 9). Applications lasting <or=5 s were usually due to catheter dislodgment. Only four patients in the remote group had applications <or=5 s compared with 11 in the conventional group (P=.041). Ablation using remote navigation was equally effective and required lower temperatures and powers (mean+/-SD temperature: 46+/-2 degrees C vs. 50+/-4 degrees C, P< .001; median [IQR] power: 29 [14] W vs. 50 [7] W, P< .001), with no difference in total energy delivered. With remote navigation, the range of impedance values between applications was less (mean+/-SD: 10.4+/-7.6 Omega vs. 19.3+/-15.4 Omega; P=.035) and the temperature variation tended to be less, suggesting greater stability between applications. There were no complications.
Conclusions: In this initial series, remote magnetic navigation was safe and effective in AVNRT ablation. Improved tissue contact reduced catheter dislodgment and necessitated a reduction in radiofrequency energy to avoid charring.