Symbolic transformations of heart rate variability preserve information about cardiac autonomic control

Dirk Cysarz, Peter Van Leeuwen, Friedrich Edelhäuser, Nicola Montano, Virend K. Somers, Alberto Porta

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Traditional measures of heart rate variability (HRV) in the time or frequency domain (e.g. standard deviation of normal-to-normal intervals, SDNN, or the high frequency component of spectral analysis, HF) may be used to track vagal and sympathetic modulation directed to the sinus node. In this study, we assess the ability of symbolic analysis to monitor cardiac autonomic regulation during two autonomic challenges (phenylephrine and nitroprusside; low and high dose of atropine). To assess the effect of the coarse graining procedure, symbolic series obtained from four different transformations over the original series and the series of successive differences of the original values. The analysis focused on patterns of length 3 and exploited a redundancy reduction strategy to group patterns into a small number of families. It turns out that each symbolic series created by the four transformations still contained sufficient dynamical features to quantify differences of cardiovascular changes during the pharmacological challenges. The symbolic series created by transformations of the beat-to-beat interview, i.e RR interval series, showed that patterns without variations (0V) appear more often during a high dose of atropine compared to rest or to a low dose of atropine. Furthermore, patterns with two unlike variations (2UV) appear more often during a low dose of atropine and less often during a high dose of atropine. Differences of nitroprusside and phenylephrine could also be assessed by patterns with these variations. In conclusion, the changes of cardiovascular regulation during pharmacological challenges can be assessed by the analysis of symbolic dynamics derived from the RR interval series independently of the specific symbolic transformation.

Original languageEnglish (US)
Pages (from-to)643-657
Number of pages15
JournalPhysiological Measurement
Issue number4
StatePublished - Apr 1 2015


  • atropine
  • autonomic nervous system
  • heart rate variability
  • nitroprusside
  • pharmacological challenge
  • phenylephrine
  • symbolic dynamics

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Biomedical Engineering
  • Physiology (medical)


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