title: Heart rate variability in patients being treated for dengue viral infection: new insights from mathematical correction of heart rate.
abstract: BACKGROUND
  Severe dengue hemorrhagic fever (DHF) is a viral infection that acts to increase permeability of capillaries, resulting in internal hemorrhage. Linear frequency domain Fourier spectral analysis represents the most published noninvasive tool for diagnosing and assessing health status via calculated heart rate variability (HRV). As such, HRV may be useful in assessing clinical status in DHF patients, but is prone to erroneous results and conclusions due to the influence of the average HR during the time period of HRV assessment (defined as the "prevailing" HR). We tested the hypothesis that alterations in HRV calculated with linear frequency analysis would be minimal when mathematically corrected for prevailing HR following dengue viral infection.
  
  
  METHODS
  Male (N = 16) and female (N = 11) patients between the ages of 6 months and 15 years of age (10 ± 6 SD years) were tracked through the progression of the dengue viral infection with treatment following the abatement of a fever (defervescence). Electrocardiographic recordings were collected and analyzed for HRV.
  
  
  RESULTS
  High frequency (HF), low frequency (LF), and LF/HF ratio were unaffected by correction for prevailing HR.
  
  
  CONCLUSIONS
  HRV corrected for changes in HR did not alter the interpretation of our data. Therefore, we conclude that cardiac parasympathetic activity (based on HF frequency) is responsible for the majority of the HR reduction following defervescence in patients with dengue viral infection.
authors.affiliation: U.S. Army Institute of Surgical Research Fort Sam Houston, TX, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Carter
authors.affiliation: U.S. Army Institute of Surgical Research Fort Sam Houston, TX, USA.
authors.forename: Carmen
authors.initials: C
authors.lastname: Hinojosa-Laborde
authors.affiliation: U.S. Army Institute of Surgical Research Fort Sam Houston, TX, USA.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Convertino
keywords: autonomic balance; dengue hemorrhagic fever; heart rate variability; high power frequency; parasympathetic nervous system