title: Spectral analysis of fetal heart rate variability in fetuses with supraventricular extrasystoles.
abstract: OBJECTIVE
  Fetal heart rate (FHR) variability is an important indicator of fetal well-being. In fetal tachyarrhythmias, however, visual analysis of FHR variability is limited. We therefore applied power spectral analysis of FHR to evaluate the fetal state.
  
  
  METHODS
  Fetal R-R intervals were detected by means of an external ECG in 3 fetuses with supraventricular extrasystoles after cardiac malformations had been excluded by fetal echocardiography. Using an autoregressive model, power spectral densities were calculated from 20 consecutive 256-beat segments for the following frequency bands: <0.03 Hz (very low frequency), 0.03-0.069 Hz (low frequency; LF), 0.07-0.129 Hz (mid-frequency) and 0.13-1.0 Hz (high frequency; HF).
  
  
  RESULTS
  The FHR variability in fetal supraventricular extrasystoles mainly resulted from the HF component (63.91 +/- 6.97%). The sympatho-vagal balance (LF/HF) was decreased in the tracings with extrasystoles (0.13).
  
  
  CONCLUSIONS
  The analysis of FHR variability in fetal supraventricular extrasystoles revealed an imbalance between sympathetic and parasympathetic regulation.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Basel, Basel, Switzerland.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Troeger
authors.forename: Andreas F
authors.initials: AF
authors.lastname: Schaub
authors.forename: Paolo
authors.initials: P
authors.lastname: Bernasconi
authors.forename: Irene
authors.initials: I
authors.lastname: Hösli
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Holzgreve
mesh_terms: D000328:Adult; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000503:physiopathology*; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D018709:Statistics, Nonparametric; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000503:physiopathology; D018879:Ventricular Premature Complexes / Q000175:diagnosis / Q000503:physiopathology*