title: Ablation of difficult right-sided accessory pathways aided by mapping of tricuspid annular activation using a Halo catheter : Halo-mapping of right sided accessory pathways.
abstract: OBJECTIVE
  To demonstrate that the use of a 20-pole catheter (Halotrade mark) positioned around the tricuspid valve annulus (TVA) is helpful in rapidly localising right free wall accessory pathways (AP), enhancing catheter stability during ablation, and leading to increased success in ablating these challenging pathways.
  
  
  METHODS
  Seven consecutive patients who underwent Halo-mapping of right-sided AP were studied. All but one had previously failed ablation. With a Halo catheter deployed at TVA, the accessory pathway location was rapidly identified using the sites of earliest atrial (A) activation during ventricular (V) pacing or orthodromic tachycardia, or earliest V-activation during sinus rhythm or A-pacing were identified. The stability of the ablation catheter was guided fluoroscopically (with reference to the stationary Halo), and electrically (contact artefact between the ablation catheter and Halo poles).
  
  
  RESULTS
  AP locations were identified by the Halo (anterior in one patient, antero-lateral in one, lateral in two, and postero-lateral in three) where similar local VA/AV intervals were recorded at both the ablation catheter and Halo bipoles recording the shortest VA/AV intervals (four of seven patients), contact artefact between the ablation catheter and those Halo bipoles was seen (six of seven patients), or both (three of seven patients). All APs were ablated successfully after a mean RF duration of 5+/-2 min, and 25+/-17 min post Halo deployment without clinical recurrence at 12+/-4 months follow-up.
  
  
  CONCLUSIONS
  A Halo positioned at the TVA can ease the localisation of right-sided AP, facilitate catheter stability during ablation, and guides successful ablation.
authors.affiliation: Waller Cardiology Department, St. Mary's Hospital and Imperial College, Praed Street, Paddington, London W2 1NY, UK. tom.wong@imperial.ac.uk
authors.forename: Tom
authors.initials: T
authors.lastname: Wong
authors.forename: Wajid
authors.initials: W
authors.lastname: Hussain
authors.forename: Vias
authors.initials: V
authors.lastname: Markides
authors.forename: Diana A
authors.initials: DA
authors.lastname: Gorog
authors.forename: Ian
authors.initials: I
authors.lastname: Wright
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Peters
authors.forename: D Wyn
authors.initials: DW
authors.lastname: Davies
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000601:surgery*; D017115:Catheter Ablation / Q000295:instrumentation*; D002404:Catheterization; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000002:abnormalities* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014261:Tricuspid Valve