Effect of respiratory rate on the relationships between RR interval and systolic blood pressure fluctuations: A frequency-dependent phenomenon

Maria Vittoria Pitzalis, Filippo Mastropasqua, Francesco Massari, Andrea Passantino, Roberto Colombo, Antonella Mannarini, Cinzia Forleo, Paolo Rizzon

Research output: Contribution to journalArticlepeer-review


Objective: The aims of this study were to determine the relationships between oscillations in systolic blood pressure and heart period at different breathing frequencies and to investigate the role of sympathetic contribution to this relationship. Methods: Fourteen healthy volunteers underwent three randomized periods of controlled breathing at 6, 10 and 16 breaths/min. ECG (RR), respiratory signal (RESP) and systolic blood pressure (SBP) were continuously recorded. The component of RR and SBP oscillations related to respiration (RR(Resp) and SBP(Resp)) was defined by means of uni- and bivariate spectral analysis. The squared coherence (K2) and phase between RR and RESP, and RR and SBP (RR-SBP) were also assessed. When the K2 of RR-SBP in the respiratory band was > 0.5, we considered the phase and calculated the closed-loop gain between the two signals. Seven subjects were also studied after chronic metoprolol treatment. Results: Although the mean values of RR and SBP did not differ between the three periods of breathing, the higher the respiratory rate, the smaller the RR(Resp) and SBP(Resp). The phase was always negative (SBP(Resp) changes preceded RR(Resp) changes), thus suggesting a baroreflex link. The higher the respiratory rate, the lower the gain and phase. Pharmacological β-adrenoceptor blockade increased the gain and shifted the phase, but the relationships found at baseline between the respiratory rate and both the gain and phase remained unchanged. Conclusions: The effect of breath rate on the relationship between heart rate and systolic pressure variabilities is a frequency-dependent phenomenon that is also independent of the sympathetic drive.

Original languageEnglish
Pages (from-to)332-339
Number of pages8
JournalCardiovascular Research
Issue number2
Publication statusPublished - May 1998


  • Baroreflex gain
  • Bode plot
  • Cardiorespiratory index
  • Heart rate variability
  • Metoprolol
  • Respiratory sinus arrhythmia
  • Systolic blood pressure variability

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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