title: Ablation of atrioventricular nodal reentrant tachycardia using remote magnetic guidance (stereotaxis) requires lower temperature and power settings because of improved local contact.
abstract: OBJECTIVE
  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.
authors.affiliation: Unidad de Arritmias, Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid, España. jmoreno@secardiologia.es
authors.forename: Javier
authors.initials: J
authors.lastname: Moreno
authors.forename: Tamara
authors.initials: T
authors.lastname: Archondo
authors.forename: Ricardo
authors.initials: R
authors.lastname: Barrios
authors.forename: Nicasio
authors.initials: N
authors.lastname: Pérez-Castellano
authors.forename: Rosa
authors.initials: R
authors.lastname: Porro
authors.forename: Jorge
authors.initials: J
authors.lastname: García Quintanilla
authors.forename: Victoria
authors.initials: V
authors.lastname: Cañadas Godoy
authors.forename: Raquel
authors.initials: R
authors.lastname: Cervigón
authors.forename: Liliana
authors.initials: L
authors.lastname: Lobo
authors.forename: Yanela
authors.initials: Y
authors.lastname: Fayad
authors.forename: Carlos
authors.initials: C
authors.lastname: Macaya
authors.forename: Julián
authors.initials: J
authors.lastname: Pérez-Villacastín
mesh_terms: D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery*