title: Assessment of pulse rate variability by the method of pulse frequency demodulation.
abstract: BACKGROUND
  Due to its easy applicability, pulse wave has been proposed as a surrogate of electrocardiogram (ECG) for the analysis of heart rate variability (HRV). However, its smoother waveform precludes accurate measurement of pulse-to-pulse interval by fiducial-point algorithms. Here we report a pulse frequency demodulation (PFDM) technique as a method for extracting instantaneous pulse rate function directly from pulse wave signal and its usefulness for assessing pulse rate variability (PRV).
  
  
  METHODS
  Simulated pulse wave signals with known pulse interval functions and actual pulse wave signals obtained from 30 subjects with a trans-dermal pulse wave device were analyzed by PFDM. The results were compared with heart rate and HRV assessed from simultaneously recorded ECG.
  
  
  RESULTS
  Analysis of simulated data revealed that the PFDM faithfully demodulates source interval function with preserving the frequency characteristics of the function, even when the intervals fluctuate rapidly over a wide range and when the signals include fluctuations in pulse height and baseline. Analysis of actual data revealed that individual means of low and high frequency components of PRV showed good agreement with those of HRV (intraclass correlation coefficient, 0.997 and 0.981, respectively).
  
  
  CONCLUSIONS
  The PFDM of pulse wave signal provides a reliable assessment of PRV. Given the popularity of pulse wave equipments, PFDM may open new ways to the studies of long-term assessment of cardiovascular variability and dynamics.
authors.affiliation: Core Laboratory, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan. hayano@med.nagoya-cu.ac.jp
authors.forename: Junichiro
authors.initials: J
authors.lastname: Hayano
authors.forename: Allan Kardec
authors.initials: AK
authors.lastname: Barros
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kamiya
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Ohte
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Yasuma
mesh_terms: D000328:Adult; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000503:physiopathology*; D001794:Blood Pressure; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D015716:Electrocardiography, Ambulatory / Q000379:methods; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000379:methods*; D011673:Pulsatile Flow; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted