title: [Analysis of local electrograms and characteristics of the ablation procedure in left-sided accessory pathways that required five or more pulses of radiofrequency].
abstract: OBJECTIVE
  Radiofrequency ablation of left sided accessory pathways requires multiple pulses in some patients due to different factors such as inadequate mapping, inappropriate tissue electrode contact and particular anatomic factors. However these characteristics have not been specifically analyzed.
  
  
  METHODS
  We have studied a prospective ablative series of 65 consecutive patients with left-sided pathways submitted to radiofrequency ablation by a simplified technique. In every application point, we analyzed the electrogram features, application point, impedance, potency and temperature.
  
  
  RESULTS
  52 patients (80%) required less than 5 radiofrequency pulses (group A) and 13 (20%) required > or = than 5 pulses (group B). The presence of a suggestive potential accessory pathway in local electrogram was similar in both groups and there were no differences in the local A-V or V-A intervals. However, in patients with pre-excitation the Delta-V interval was shorter in group A than in group B (8 ms vs 15 ms; p < 0.001). Furthermore, the impedance observed from the ablation point in group A was lower (108 +/- 12 vs 121 +/- 22 ohms; p < 0.001), and the maximum watts required to reach the predetermined temperature was higher in group A (42 +/- 16 vs 31 +/- 18 watts; p < 0.001). Final success of the procedure was 100%.
  
  
  CONCLUSIONS
  Patients requiring more than 5 radiofrequency pulses had electrograms and tissue contact equal or better than those requiring less than 5 pulses. This suggests that difficulties encountered in some procedures can be due to anatomical factors rather than inaccurate mapping or insufficient tissue contact.
authors.affiliation: Unidad de Arritmias, Hospital Clínic, Universidad de Barcelona. jllmont@medicina.ub.es
authors.forename: L
authors.initials: L
authors.lastname: Mont
authors.forename: M
authors.initials: M
authors.lastname: Valentino
authors.forename: M
authors.initials: M
authors.lastname: Vacca
authors.forename: L
authors.initials: L
authors.lastname: Aguinaga
authors.forename: M
authors.initials: M
authors.lastname: Matas
authors.forename: B
authors.initials: B
authors.lastname: Herreros
authors.forename: J
authors.initials: J
authors.lastname: Brugada
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014927:Wolff-Parkinson-White Syndrome / Q000601:surgery*
vernacular_title: Análisis de los electrogramas locales y de las características de la ablación en vías accesorias izquierdas que requirieron cinco o más applicaciones de radiofrecuencia.