title: Effects of disopyramide on the atrial fibrillation threshold in the human atrium.
abstract: The effects of disopyramide on the atrial fibrillation threshold (AFT) in the human atrium were investigated. To evaluate atrial vulnerability, the following electrophysiologic parameters were measured before and after the administration of disopyramide (2 mg/kg) in 12 patients with paroxysmal atrial fibrillation: The right atrial effective refractory period (ERP) and percentage maximum atrial fragmentation (%MAF) were measured by atrial premature stimulation based on a cycle length of 500 ms. The inter-atrial conduction time (ACT) was measured by burst pacing (120/min) for 30 s. AFT was measured by applying a high-frequency (50 Hz) stimulation for 1 s given at the right atrial appendage. AFT was defined as the lowest intensity of electrical current that could induce atrial fibrillation lasting for more than 30 s. Disopyramide significantly reduced %MAF, and prolonged ERP and ACT. AFT was measured in all patients and the mean AFT was 3.1 +/- 1.7 mA. After the administration of disopyramide, AFT significantly increased to 6.1 +/- 3.6 mA. There was a positive correlation between ERP and AFT, and a negative correlation between %MAF and AFT. No correlation was detected between ACT and AFT. In conclusion, disopyramide increased AFT in the human atrium.
authors: Second Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors: K
authors: K
authors: Ishibashi
authors: D
authors: D
authors: Inoue
authors: R
authors: R
authors: Sakai
authors: M
authors: M
authors: Inoue
authors: T
authors: T
authors: Shirayama
authors: J
authors: J
authors: Asayama
authors: M
authors: M
authors: Nakagawa
mesh_terms: D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000503:physiopathology*; D016275:Atrial Function / Q000187:drug effects*; D004206:Disopyramide / Q000494:pharmacology* / Q000627:therapeutic use; D004594:Electrophysiology; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D012044:Regression Analysis
chemical_list: D000889:Anti-Arrhythmia Agents; D004206:Disopyramide