title: Modulation of cardiac autonomic nervous activity early after cardioversion of atrial fibrillation by biphasic waveform.
abstract: BACKGROUND
  Imbalance of cardiac autonomic nervous modulation might prominently contribute to early relapses of atrial fibrillation (AF) after cardioversion (CV). The biphasic (Bi) waveform is more effective than the monophasic (Mo) waveform in CV of AF. Whether these waveforms have different effects on autonomic modulation early after CV is unknown.
  
  
  METHODS
  We investigated 171 consecutive patients after successful electrical CV (mean age 65.4 years, 82% male, 80% structural heart disease). Bi waveform was used in 89, Mo waveform in 82. Heart rate variability (HRV) was analyzed from 24-hour Holter recordings, started directly after CV.
  
  
  RESULTS
  Mean delivered total energy was significantly lower in the Bi group (Bi 223 +/- 163 W, Mo 355 +/- 211 W, P < 0.001). Mean RR interval decreased within 5 hours after CV and increased again within the remaining hours, without significant differences between Bi and Mo groups. Time courses of time domain parameters of HRV revealed Bi profiles with the lowest levels 6 hours after CV in both groups. However, the hourly values of HRV were significantly higher in the Bi subgroup.
  
  
  CONCLUSIONS
  Our study indicates that waveform and total delivered energy significantly influence autonomic modulation of the sinus node in the early phase after CV of AF. In contrast to Bi CV, Mo CV is characterized by a significant decrease of cardiac vagal modulation, which may have an arrhythmic effect by increasing the degree of early electrical stunning after CV of AF.
authors.affiliation: Medizinische Klinik II, Universität zu Lübeck, Lübeck, Germany.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Ortak
authors.forename: Franziska
authors.initials: F
authors.lastname: Kurtz
authors.forename: Ann-Sophie
authors.initials: AS
authors.lastname: Krenzien
authors.forename: Nina
authors.initials: N
authors.lastname: Janca
authors.forename: Iris
authors.initials: I
authors.lastname: Wilke
authors.forename: Melanie
authors.initials: M
authors.lastname: Barantke
authors.forename: Frank
authors.initials: F
authors.lastname: Eberhardt
authors.forename: Uwe K H
authors.initials: UK
authors.lastname: Wiegand
authors.forename: Heribert
authors.initials: H
authors.lastname: Schunkert
authors.forename: Hendrik
authors.initials: H
authors.lastname: Bonnemeier
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D004554:Electric Countershock; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012849:Sinoatrial Node / Q000294:innervation / Q000503:physiopathology; D014630:Vagus Nerve / Q000503:physiopathology