title: Effects of isoproterenol and amiodarone on the double potential interval after ablation of the cavotricuspid isthmus.
abstract: BACKGROUND
  A corridor of double potentials along the ablation line has been recognized to be an indicator of complete cavotricuspid isthmus block. Isoproterenol is used to confirm cavotricuspid isthmus block, but the effects of isoproterenol on the double potential interval (DPI), either in the absence or presence of amiodarone, are unknown.
  
  
  RESULTS
  Thirty-two patients with isthmus-dependent atrial flutter underwent successful ablation of the cavotricuspid isthmus. The procedure was performed in the drug-free state in 23 patients, and 2 to 7 days after discontinuation of chronic amiodarone therapy in 9 patients. Electrograms recorded along the ablation line before and during isoproterenol infusion were analyzed after isthmus block was achieved. Double potentials were recorded along the entire ablation line upon achievement of complete isthmus block in all patients. The DPI in 9 patients treated with amiodarone was longer than in the other patients (147 +/- 32 msec vs 119 +/- 19 msec, P < 0.001). The DPI increased as the pacing cycle length shortened in patients treated with amiodarone, but not in the other patients. At all pacing cycle lengths, isoproterenol shortened the DPI to a greater extent in the patients treated with amiodarone than in the other patients.
  
  
  CONCLUSIONS
  Amiodarone results in rate-dependent prolongation of the DPI during coronary sinus pacing after ablation of the cavotricuspid isthmus. Isoproterenol shortens the DPI despite the presence of complete isthmus block, and this effect is accentuated in the presence of amiodarone.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, MI 48109, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tada
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozaydin
authors.forename: Aman
authors.initials: A
authors.lastname: Chugh
authors.forename: Christoph
authors.initials: C
authors.lastname: Scharf
authors.forename: Hakan
authors.initials: H
authors.lastname: Oral
authors.forename: Frank
authors.initials: F
authors.lastname: Pelosi
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Knight
authors.forename: S Adam
authors.initials: SA
authors.lastname: Strickberger
authors.forename: Fred
authors.initials: F
authors.lastname: Morady
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000368:Aged; D000638:Amiodarone / Q000494:pharmacology*; D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D004357:Drug Synergism; D004594:Electrophysiology; D005260:Female; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000187:drug effects; D014261:Tricuspid Valve / Q000601:surgery*; D014684:Venae Cavae / Q000601:surgery*
chemical_list: D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D007545:Isoproterenol; D000638:Amiodarone