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