title: Variations in duration and composition of the excitable gap around the tricuspid annulus during typical atrial flutter.
abstract: BACKGROUND
  Differences in the duration of the excitable gap along the reentry circuit during typical atrial flutter are poorly known.
  
  
  OBJECTIVE
  To prospectively evaluate and compare the duration and composition of the excitable gap during typical counterclockwise atrial flutter in different parts of the circuit all around the tricuspid annulus.
  
  
  METHODS
  The excitable gap was determined by introducing a premature stimulus at various sites around the tricuspid annulus during typical counterclockwise atrial flutter in 34 patients. Excitable gap was calculated as the difference between the longest resetting coupling interval and the effective atrial refractory period.
  
  
  RESULTS
  The duration of the excitable gap, the effective atrial refractory period and the resetting coupling interval differed significantly along the tricuspid annulus. Duration of excitable gap was significantly longer at the low lateral right atrium (79±22 ms) than at the cavotricuspid isthmus (66±23 ms; P=0.002). The effective atrial refractory period was significantly longer at the cavotricuspid isthmus (160±26 ms) than at the high lateral right atrium (149±29 ms; P=0.004). Other locations, such as coronary sinus ostium, right atrial septum and atrial roof displayed intermediate values.
  
  
  CONCLUSIONS
  The duration of the excitable gap differed significantly along the tricuspid annulus, with a larger excitable gap at the lateral right atrium and a shorter excitable gap at the cavotricuspid isthmus, because of longer refractory periods at the isthmus.
authors.affiliation: Unité de rythmologie et de stimulation cardiaque, fédération de cardiologie, university hospital Rangueil, 31059 Toulouse cedex 09, France. mauryjphil@hotmail.com
authors.forename: Philippe
authors.initials: P
authors.lastname: Maury
authors.forename: Joelle
authors.initials: J
authors.lastname: Fourcade
authors.forename: Alexandre
authors.initials: A
authors.lastname: Duparc
authors.forename: Pierre
authors.initials: P
authors.lastname: Mondoly
authors.forename: Anne
authors.initials: A
authors.lastname: Rollin
authors.forename: Nicolas
authors.initials: N
authors.lastname: Detis
authors.forename: Aurelien
authors.initials: A
authors.lastname: Hebrard
authors.forename: Marc
authors.initials: M
authors.lastname: Delay
authors.forename: Meyer
authors.initials: M
authors.lastname: Elbaz
authors.forename: Didier
authors.initials: D
authors.lastname: Carrie
authors.forename: Michel
authors.initials: M
authors.lastname: Galinier
mesh_terms: D000200:Action Potentials; D000368:Aged; D000369:Aged, 80 and over; D001282:Atrial Flutter / Q000503:physiopathology* / Q000601:surgery; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005602:France; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D012032:Refractory Period, Electrophysiological; D012086:Reoperation; D013997:Time Factors; D016896:Treatment Outcome; D014261:Tricuspid Valve / Q000503:physiopathology*