title: Excitable gap composition in the presence of antiarrhythmic drugs in common human atrial flutter.
abstract: OBJECTIVE
  Recurrence of atrial flutter (AFl) on antiarrhythmic drugs is frequently observed. To determine the reasons for drug inefficacy, the electrophysiological parameters of AFl were studied in eight patients without drug, six patients on sotalol (Sot), eight patients on amiodarone (Amio) and four patients on propafenone (PPF) who presented to the electrophysiology laboratory for conversion of AFl by rapid atrial pacing.
  
  
  METHODS
  A quadripolar electrode catheter was positioned in the right atrium in the pathway of the AFl circuit. The duration and composition of the excitable gap (EG) were determined by premature stimuli during AFl.
  
  
  RESULTS
  The EG in AFl recurring on Sot (80 +/- 25 ms), Amio (78 +/- 13 ms) and PPF (83 +/- 26 ms) was not significantly different from that without drug (88 +/- 14 ms). Furthermore, a fully excitable portion of the EG was present whether with or without drug.
  
  
  CONCLUSIONS
  AFl recurrence on Amio, PPF or Sot is associated with the continued presence of an EG and fully excitable portion. These findings explain the persistent viability of the AFl circuit despite drug therapy in these patients.
authors.affiliation: The Research Center of Sacré-Coeur Hospital, Montréal, Québec.
authors.forename: Elise
authors.initials: E
authors.lastname: Jalil
authors.forename: Boualem
authors.initials: B
authors.lastname: Mensour
authors.forename: Alain
authors.initials: A
authors.lastname: Vinet
authors.forename: Teresa
authors.initials: T
authors.lastname: Kus
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000638:Amiodarone / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001282:Atrial Flutter / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011405:Propafenone / Q000627:therapeutic use; D012107:Research Design; D013015:Sotalol / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D011405:Propafenone; D013015:Sotalol; D000638:Amiodarone