title: Non-invasive evaluation of ventricular refractoriness and its dispersion during ventricular fibrillation in patients with implantable cardioverter defibrillator.
abstract: BACKGROUND
  Local ventricular refractoriness and its dispersion during ventricular fibrillation (VF) have not been well evaluated, due to methodological difficulties.
  
  
  METHODS
  In this study, a non-invasive method was used in evaluation of local ventricular refractoriness and its dispersion during induced VF in 11 patients with VF and/or polymorphic ventricular tachycardia (VT) who have implanted an implantable cardioverter defibrillator (ICD). Bipolar electrograms were simultaneously recorded from the lower oesophagus behind the posterior left ventricle (LV) via an oesophageal electrode and from the right ventricular (RV) apex via telemetry from the implanted ICD. VF intervals were used as an estimate of the ventricular effective refractory period (VERP). In 6 patients, VERP was also measured during sinus rhythm at the RV apex and outflow tract (RVOT) using conventional extra stimulus technique.
  
  
  RESULTS
  Electrograms recorded from the RV apex and the lower esophagus behind the posterior LV manifested distinct differences of the local ventricular activities. The estimated VERPs during induced VF in the RV apex were significantly shorter than that measured during sinus rhythm using extra stimulus technique. The maximal dispersion of the estimated VERPs during induced VF between the RV apex and posterior LV was that of 10 percentile VF interval (40 +/- 27 ms), that is markedly greater than the previously reported dispersion of ventricular repolarization without malignant ventricular arrhythmias (30-36 ms).
  
  
  CONCLUSIONS
  This study verified the feasibility of recording local ventricular activities via oesophageal electrode and via telemetry from an implanted ICD and the usefulness of VF intervals obtained using this non-invasive technique in evaluation of the dispersion of refractoriness in patients with ICD implantation.
authors.affiliation: Department of Cardiology, University Hospital, Lund University, Lund, Sweden. Jijian.Luo@kard.lu.se
authors.forename: Jijian
authors.initials: J
authors.lastname: Luo
authors.forename: Carl Magnus
authors.initials: CM
authors.lastname: Pripp
authors.forename: Eva
authors.initials: E
authors.lastname: Hertervig
authors.forename: Ole
authors.initials: O
authors.lastname: Kongstad
authors.forename: Erik
authors.initials: E
authors.lastname: Ljungström
authors.forename: S Bertil
authors.initials: SB
authors.lastname: Olsson
authors.forename: Shiwen
authors.initials: S
authors.lastname: Yuan
mesh_terms: D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D013686:Telemetry / Q000379:methods*; D014693:Ventricular Fibrillation / Q000503:physiopathology*; D016276:Ventricular Function / Q000502:physiology