An Application of Chaos Theory for Estimation of Simultaneous   Variability of RR-intervals in Heart and Systolic Blood Pressure in Humans
  We introduce a new method to estimate BaroReflex Sensitivity (BRS) . The methodology, based on the CZF formulation, recently published (see Conte et al 2008), enables to evaluate simultaneous variability of RR and SBP and to estimate the coupling strength. The technique is applied to subjects (female and men with age ranging from 21 to 28 years old) and it is compared with the results that may be obtained by using the standard Fourier spectral analysis technique. The comparison is also performed by using the technique of Lomb-Scargle periodogram, based on Fourier analysis. 
Elio Conte, Antonio Federici, Joseph P. Zbilut