title: Radiofrequency current delivery by way of a bipolar tricuspid annulus-mitral annulus electrode configuration for ablation of posteroseptal accessory pathways.
abstract: OBJECTIVE
  This report describes a novel technique for ablation of "difficult" posteroseptal pathways.
  
  
  BACKGROUND
  Although radiofrequency ablation of accessory atrioventricular (AV) pathways is successful in > or = 90% of cases, particular difficulty may be encountered with some bypass tracts in the posteroseptal region.
  
  
  METHODS
  In eight patients with posteroseptal accessory pathways (two concealed), radiofrequency catheter ablation using conventional unipolar current applications from favorable sites along the tricuspid or mitral annulus, or both, was unsuccessful. Subsequently, a bipolar technique was adopted, with current application between the distal electrodes of two catheters positioned against the septal region at sites of early activation along both mitral and tricuspid annuli.
  
  
  RESULTS
  The bipolar configuration proved effective in all cases. The number of bipolar lesions required for success was one (five patients), five (two patients) and nine (one patient). In five patients, bipolar current application abolished pathway conduction using positions at which delivery of unipolar lesions had been ineffective or caused transient block. The AV or ventriculoatrial interval at successful sites varied from 20 to 65 ms, and the time from delta wave onset to local ventricular activation was zero or negative. There were no complications attributable to the bipolar technique. During follow-up of 8 to 36 weeks, pathway conduction has not recurred in any patient.
  
  
  CONCLUSIONS
  Bipolar radiofrequency current delivery across the septal region using a tricuspid annulus-mitral annulus electrode configuration may abolish accessory pathway conduction when conventional unipolar applications have proved ineffective. The technique may reduce procedure duration, radiation exposure and overall failure rate in these problematic cases.
authors.affiliation: Department of Cardiological Sciences, Saint George's Hospital Medical School, London, England, United Kingdom.
authors.forename: Y
authors.initials: Y
authors.lastname: Bashir
authors.forename: S C
authors.initials: SC
authors.lastname: Heald
authors.forename: S
authors.initials: S
authors.lastname: O'Nunain
authors.forename: D
authors.initials: D
authors.lastname: Katritsis
authors.forename: A J
authors.initials: AJ
authors.lastname: Camm
authors.forename: D E
authors.initials: DE
authors.lastname: Ward
mesh_terms: D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation / Q000601:surgery; D001282:Atrial Flutter / Q000601:surgery; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods; D004562:Electrocardiography; D004566:Electrodes; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery*; D016896:Treatment Outcome; D014261:Tricuspid Valve / Q000601:surgery; D014927:Wolff-Parkinson-White Syndrome / Q000503:physiopathology / Q000601:surgery