title: The role of local voltage potentials in outflow tract ectopy.
abstract: OBJECTIVE
  Discrete, fragmented, local voltage potentials (LVPs) have been observed in electrograms recorded at the ablation site in patients undergoing radiofrequency ablation for arrhythmias originating in both the right and left ventricular outflow tract; however, the incidence and the significance of the LVP with respect to arrhythmogenesis is uncertain.
  
  
  RESULTS
  We studied 25 patients with outflow tract arrhythmias referred for radiofrequency catheter ablation and recorded high-amplified intracardiac electrograms close to the site of origin of the arrhythmia. Ten patients undergoing ablation for supraventricular arrhythmias served as controls. During sinus rhythm, LVPs were recorded in 24 of the 25 patients, 10-85 ms (41 +/- 19 ms) after the onset of the QRS complex, duration 33 +/- 11 ms, voltage 2.0 +/- 1.5 mV. The same potential was recorded 10-52 ms (mean 37 +/- 11 ms) prior to the V potential in the ventricular premature beats. In 10 patients, ventricular parasystole was suggested by varying coupling intervals >100 ms, and fusion beats allowing for the estimation of the least common denominator of R-R intervals. In 23 of the 25 patients, the 12-lead electrocardiogram (ECG) and intracardiac contact mapping located the arrhythmias to an area of 3-4 cm(2) in the septal region of the right ventricular outflow tract; in two patients, the site of origin was in the left coronary cusp. Radiofrequency ablation carried out in 24 of the 25 patients was successful in 21 patients, and after successful ablation, the LVP could still be recorded in all these 21 patients. The LVP was not present in 10 controls.
  
  
  CONCLUSIONS
  Local potentials are recorded close to the site of origin of ventricular ectopy in >90% of patients with idiopathic outflow tract ectopy and imply successful ablation. The potentials may reflect an area of depressed conductivity known to be a prerequisite for experimental ventricular ectopy including parasystole.
authors.affiliation: Cardiology Department, Gentofte University Hospital, Niels Andersensvej 65, Copenhagen 2900, Denmark. pebt@geh.regionh.dk
authors.forename: Poul Erik
authors.initials: PE
authors.lastname: Bloch Thomsen
authors.forename: Arne
authors.initials: A
authors.lastname: Johannessen
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
authors.forename: Thomas Fritz
authors.initials: TF
authors.lastname: Hansen
authors.forename: Jørgen Kim
authors.initials: JK
authors.lastname: Kanters
authors.forename: Jens
authors.initials: J
authors.lastname: Haarbo
authors.forename: Jim
authors.initials: J
authors.lastname: Hansen
authors.forename: Liselotte Klint
authors.initials: LK
authors.lastname: Christiansen
authors.forename: Peter
authors.initials: P
authors.lastname: Sogaard
authors.forename: Knud
authors.initials: K
authors.lastname: Saermark
authors.forename: Charles
authors.initials: C
authors.lastname: Antzelevitch
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017574:Parasystole / Q000175:diagnosis / Q000503:physiopathology; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D018879:Ventricular Premature Complexes / Q000175:diagnosis / Q000503:physiopathology