title: Prolonged fractionation of paced right atrial electrograms in patients with atrial flutter and fibrillation.
abstract: OBJECTIVE
  This study investigated the extent of fractionation of paced right atrial electrograms in patients with and without paroxysmal atrial flutter (AFL) or atrial fibrillation (AF).
  
  
  BACKGROUND
  Slow conduction through nonuniform anisotropic atrial muscles, represented by fractionated electrograms, may favor the generation of atrial tachyarrhythmias.
  
  
  METHODS
  This study included 10 control patients (Group 1), 8 patients with documented paroxysmal AFL (Group 2) and 10 patients with documented paroxysmal AF (Group 3). Five electrode catheters were placed in the different sites of the right atrium and one catheter was positioned at the coronary sinus ostium. Atrial pacing from one site was done by a constant drive train with an extrastimulus inserted every fourth beat while recording at the other five sites was performed. The delay of each fractionated potential in the high-pass filtered atrial electrogram in response to extrastimulation was determined and used to construct conduction curves of delay versus the S1S2 interval.
  
  
  RESULTS
  The mean increase in electrogram duration between a coupling interval of 350 ms and 10 ms above atrial refractoriness was significantly greater in Groups 2 and 3 compared with that in Group 1 (8.5 +/- 2.5 vs. 11.0 +/- 2.7 vs. 5.9 +/- 2.3 ms, respectively, p < 0.001). The mean S1S2 interval at which delay increased suddenly was also longer in Groups 2 and 3 compared with Group 1 (326 +/- 9 vs. 343 +/- 12 vs. 307 +/- 17 ms, respectively, p < 0.001).
  
  
  CONCLUSIONS
  Increased delays in the individual potential of the fractionated atrial electrograms may be related to the development of AFL and AF.
authors.affiliation: Department of Medicine, National Yang-Ming University School of Medicine, Taipei Veterans General Hospital, Taiwan. cttai@vghtpe.gov.tw
authors.forename: C T
authors.initials: CT
authors.lastname: Tai
authors.forename: S A
authors.initials: SA
authors.lastname: Chen
authors.forename: J W
authors.initials: JW
authors.lastname: Tzeng
authors.forename: B I
authors.initials: BI
authors.lastname: Kuo
authors.forename: Y A
authors.initials: YA
authors.lastname: Ding
authors.forename: M S
authors.initials: MS
authors.lastname: Chang
authors.forename: L Y
authors.initials: LY
authors.lastname: Shyu
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology*; D001282:Atrial Flutter / Q000175:diagnosis / Q000209:etiology*; D002304:Cardiac Pacing, Artificial / Q000379:methods; D016022:Case-Control Studies; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors