title: Reasons for prolonged or failed attempts at radiofrequency catheter ablation of accessory pathways.
abstract: OBJECTIVE
  The purpose of this study was to categorize the reasons for a prolonged or failed procedure in a series of patients undergoing catheter ablation of an accessory pathway.
  
  
  BACKGROUND
  Radiofrequency ablation of accessory pathways at times requires a lengthy procedure or a second ablation session, or both, and not prior studies have systematically investigated the reasons for this.
  
  
  METHODS
  In a consecutive series of 619 patients undergoing catheter ablation of an accessory pathway, the mean ablation time +/- SD was 68 +/- 64 min. The subjects of this study were 14 patients who had an ablation time >2 SD greater than the mean (>196 min) and 51 patients who required a second ablation session for a successful outcome. The accessory pathway in the 65 patients in this study was located in the right free wall in 19 patients (29%), septum in 14 (22%) and left free wall in 32 (49%).
  
  
  RESULTS
  The primary reasons for a lengthy or failed ablation attempt were 1) inability to position the ablation catheter at the effective target site (16 patients, 25%); 2) instability of the ablation catheter or inadequate tissue contact at the target site, or both (15 patients, 23%); 3) mapping error due to an oblique course of the accessory pathway (7 patients, 11%); 4) failure to recognize a posteroseptal accessory pathway as being left-sided instead of right-sided (4 patients, 6%); 5) other errors in accessory pathway localization (6 patients, 9%); 6) epicardial location of the accessory pathway (5 patients, 8%); 7) recurrent atrial fibrillation (2 patients, 3%); 8) occurrence of a complication (2 patients, 3%); 9) unusual right-sided accessory pathway that inserted in the anterior right ventricle, 2 cm away from the lateral tricuspid annulus (1 patient, 1.5%); and 10) unexplained factors (7 patients, 11%). The most common effective strategies employed to achieve a successful outcome in these patients were 1) substitution of a more experienced operator; 2) use of ablation catheters of varying configurations; 3) switching from a retrograde aortic to a trans-septal approach; 4) switching from an inferior to a superior vena caval approach; 5) use of a 60-cm guiding sheath; 6) detailed mapping of the atrial or ventricular insertion of the accessory pathway; and 7) searching within the coronary sinus for a presumed accessory pathway potential.
  
  
  CONCLUSIONS
  A lengthy or failed attempt at catheter ablation of an accessory pathway may be due to a variety of reasons, the most common of which are problems related to some aspect of catheter manipulation and errors in accessory pathway localization. Knowledge of the most common reasons for a lengthy or ineffective procedure may facilitate successful outcome of accessory pathway ablation.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0022, USA.
authors.forename: F
authors.initials: F
authors.lastname: Morady
authors.forename: A
authors.initials: A
authors.lastname: Strickberger
authors.forename: K C
authors.initials: KC
authors.lastname: Man
authors.forename: E
authors.initials: E
authors.lastname: Daoud
authors.forename: M
authors.initials: M
authors.lastname: Niebauer
authors.forename: R
authors.initials: R
authors.lastname: Goyal
authors.forename: M
authors.initials: M
authors.lastname: Harvey
authors.forename: F
authors.initials: F
authors.lastname: Bogun
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000601:surgery*; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D015986:Confounding Factors, Epidemiologic; D004868:Equipment Failure; D005260:Female; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D013997:Time Factors; D017211:Treatment Failure