title: Effects of isoproterenol and propranolol on the inducibility and frequency of ventricular fibrillation in patients with Brugada syndrome.
abstract: BACKGROUND
  Isoproterenol (ISP), a beta-adrenergic agonist, suppresses arrhythmic storm in patients with sporadic Brugada syndrome (BS). However, the influence of ISP and the beta-adrenergic antagonist propranolol (PRO) on the inducibility and frequency of ventricular fibrillation (VF) in BS patients remains unclear.
  
  
  RESULTS
  Twenty-seven BS patients with induced VF>10s in a control state were enrolled. Electrophysiological stimulation (EPS) testing was performed during ISP and after PRO in selected patients. The inducibility and frequency of VF were compared. Dominant frequency (DF) was obtained by Fast Fourier transform from 4-s data (phase) and sequentially every 2s up to phase 5. ISP prevented induction of VF in 20 of 25 patients (80%). During ISP, 5 patients experienced induction of VF. ISP significantly influenced DF transition compared with the control state. DF gradually increased but was unchanged after the middle phase. PRO had no effect on incidence of induced VF in 5 patients; increased PRO induced VF in 5 (83.3%) of 6 patients who tested negative during ISP. After PRO, 10 patients experienced induction of VF. Thus, PRO significantly influenced DF transition. DF after PRO was higher than that in the corresponding phase in the control state.
  
  
  CONCLUSIONS
  ISP suppressed induction of VF and the increase of DF with time. PRO aggravated VF and accelerated DF.
authors.affiliation: Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Omiya
authors.forename: Akihiko
authors.initials: A
authors.lastname: Shimizu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ueyama
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshiga
authors.forename: Masahiro
authors.initials: M
authors.lastname: Doi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hiratsuka
authors.forename: Masakazu
authors.initials: M
authors.lastname: Fukuda
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Masunori
authors.initials: M
authors.lastname: Matsuzaki
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology* / Q000627:therapeutic use; D000319:Adrenergic beta-Antagonists / Q000009:adverse effects / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D053840:Brugada Syndrome / Q000150:complications*; D004562:Electrocardiography; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000009:adverse effects / Q000494:pharmacology*; D014693:Ventricular Fibrillation / Q000209:etiology*
chemical_list: D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D007545:Isoproterenol