title: Heart rate variability following neonatal heart surgery for complex congenital heart disease.
abstract: BACKGROUND
  Altered cardiac autonomic control may play a role in the morbidity and mortality suffered by neonates who undergo surgery for complex congenital heart disease (CHD). The purpose of this study was to evaluate cardiac autonomic activity, as measured by spectral indices of heart rate variability (HRV), prior to and early after infant surgery for CHD and attempt to correlate HRV indices with clinical outcome. In addition, we assessed the hypothesis that single-ventricle physiology and surgical interruption of the great arteries negatively affects HRV.
  
  
  METHODS
  Sixty neonates prospectively wore 24-hour Holter monitors at three time points: before and early after CHD surgery, and at 3- to 6-month follow-up. Standard spectral indices of HRV were measured.
  
  
  RESULTS
  In the early postoperative time point, patients with single-ventricle physiology had lower low-frequency power (LF) compared to patients with two ventricles (P=0.040). Surgical interruption of the great arteries did not affect HRV in this cohort. For the entire cohort, LF (P=0.004) and high-frequency power (HF) (P<0.001) increased over the three time points, while LF/HF (P=0.119) did not significantly change. In the multivariable linear regression model, significant predictors of longer postoperative hospital stay included longer total support time (P=or<0.001), longer duration of inotrope support (P=0.012), elevated mean heart rate at postoperative time point (P=0.002), and lower LF/HF ratio at the postoperative time point (P=0.014).
  
  
  CONCLUSIONS
  Patients with single-ventricle physiology have a significant physiologic reduction in LF in the early postoperative period compared to patients with two ventricles. Diminished cardiac autonomic control is associated with longer hospitalization following neonatal cardiac surgery.
authors.affiliation: Division of Cardiology, University of Pennsylvania School of Medicine, and The Cardiac Center at The Children's Hospital of Philadelphia, Pennsylvania 19104, USA. kaltman@email.chop.edu
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Kaltman
authors.forename: Brian D
authors.initials: BD
authors.lastname: Hanna
authors.forename: Paul R
authors.initials: PR
authors.lastname: Gallagher
authors.forename: J William
authors.initials: JW
authors.lastname: Gaynor
authors.forename: Rodolfo I
authors.initials: RI
authors.lastname: Godinez
authors.forename: Ronn E
authors.initials: RE
authors.lastname: Tanel
authors.forename: Maully J
authors.initials: MJ
authors.lastname: Shah
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Vetter
authors.forename: Larry A
authors.initials: LA
authors.lastname: Rhodes
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery*; D015331:Cohort Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006330:Heart Defects, Congenital / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D016896:Treatment Outcome