title: Electrophysiological characteristics of complex fractionated electrograms and high frequency activity in atrial fibrillation.
abstract: BACKGROUND
  It is unclear whether atrial substrate with complex fractionated electrograms (CFAEs) is related to arrhythmogenesis. This study aimed to investigate the electrophysiology in CFAE and high dominant frequency (DF) areas.
  
  
  RESULTS
  Atrial fibrillation (AF) was induced by rapid atrial pacing in heart failure (HF) rabbits (4 weeks after coronary artery ligation). Real-time substrate mapping, multielectrode array, and monophasic action potential recordings were used to study areas of CFAE and DF. Conventional microelectrode and western blot were used to record the action potentials (APs) and protein expression in isolated tissue preparations. CFAE site with high DF had the most depolarized resting membrane potential, highest incidence of early and delayed afterdepolarizations, and steepest maxima slope of 90% of AP duration (APD90) restitution curve (RC) compared to CFAE site with low DF or non-CFAE sites. CFAE site with high DF exhibited the slowest conduction velocity and shortest wavelength than the other areas. Upregulation of the Na(+)-Ca(2+) exchanger (NCX), apamin-sensitive small-conductance Ca(2+)-activated K(+) channel type 2 (SK2) and sarcoplasmic reticulum Ca(2+)-ATPase, and downregulation of the Kir2.1 were found at CFAE site with high DF compared to that observed in the 3 other areas. Inhibition of the NCX and SK channels prolonged the APD90, flattened the maximum slope of RC, and suppressed AF.
  
  
  CONCLUSIONS
  CFAE site with high DF had an arrhythmogenic property differing significantly from the other areas of LA in an HF rabbit model, which may contribute to the genesis of AF.
authors: Institute of Clinical Medicine and Department of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan; Division of Cardiology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors: Shih-Lin
authors: SL
authors: Chang
authors: Yao-Chang
authors: YC
authors: Chen
authors: Chiao-Po
authors: CP
authors: Hsu
authors: Yu-Hsun
authors: YH
authors: Kao
authors: Yung-Kuo
authors: YK
authors: Lin
authors: Yenn-Jiang
authors: YJ
authors: Lin
authors: Tsu-Juey
authors: TJ
authors: Wu
authors: Shih-Ann
authors: SA
authors: Chen
authors: Yi-Jen
authors: YJ
authors: Chen
mesh_terms: D000200:Action Potentials; D000818:Animals; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology*; D004195:Disease Models, Animal; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D011817:Rabbits
keywords: Atrial fibrillation; Complex fractionated electrograms; Dominant frequency; Heart failure