Heart rate non linear dynamics in patients with persistent vegetative state: A preliminary report

Marco Sarà, Fabio Sebastiano, Simona Sacco, Francesca Pistoia, Paolo Onorati, Giorgio Albertini, Antonio Carolei

Research output: Contribution to journalArticlepeer-review


Primary objective: This study evaluated the hypothesis that neural networks derangement in patients with a vegetative state (VS) may cause an alteration of heart rate (HR) non-linear pattern. Methods and procedures: Fifteen consecutive patients with a persistent VS and 15 matched healthy control subjects were included in the study. A 6-hour continuous electrocardiographic recording was used for the time series analysis measuring the occurrence time of the intervals between consecutive normal sinus heart beats (RR' intervals). Parameters evaluating linear and non-linear HR variability were studied. Approximate Entropy (ApEn), a non-linear parameter that quantifies the unpredictability of fluctuations in an instantaneous HR time series, was calculated from the average values of time series with fixed input variables. Main outcomes and results: All linear parameters, with the only exception being the percentage of RR' intervals that were by at least 50 ms different from the previous interval (0.56, SD = 1.31 vs 10.35, SD = 12.58; p = 0.005) were similar in patients and in healthy control subjects. Mean ApEn values (0.68, SD = 0.24 vs 1.10, SD = 0.16; p = 0.0001) were lower in patients than in healthy control subjects. Conclusions: The findings support the hypothesis that derangement of neural networks may cause a reduction of non-linear behaviour in HR such as ApEn.

Original languageEnglish
Pages (from-to)33-37
Number of pages5
JournalBrain Injury
Issue number1
Publication statusPublished - Jan 2008


  • Approximate entropy
  • Heart rate dynamics
  • Minimally conscious state
  • Vegetative state

ASJC Scopus subject areas

  • Clinical Neurology


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