Pure autonomic failure: Complex abnormalities in the neural mechanisms regulating the cardiovascular system

Raffaello Furlan, Simona Piazza, Maurizio Bevilacqua, Maurizio Turiel, Guido Norbiato, Federico Lombardi, Alberto Malliani

Research output: Contribution to journalArticlepeer-review


The aim of this study was to evaluate the sympatho-vagal interaction modulating cardiovascular function and the possible impairment of baroreceptor sensitivity in patients affected by Pure Autonomic Failure (PAF). We studied 4 patients affected by PAF and 7 controls at rest and during different levels (45°, 60°, 90°) of head-up tilt. On a different day all subjects underwent i.v. administration of phenylephrine at dosages adequate to enhance systolic blood pressure by about 20 mmHg both at rest and during 45° head-up tilt. Finally, 1.5 mg atropine was infused intravenously only in the patients. Spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided markers of sympathetic (low-frequency oscillations, about 0.1 Hz, LFRR) and vagal (high-frequency oscillations, about 0.25 Hz, HFRR) modulations of heart period and of sympathetic vasomotor activity (low-frequency oscillations of SAP variability, LFSAP). Baroreceptor mechanisms were quantified by means of the index α (calculated from the square root of the ratio between the powers of HF components of RR interval and SAP variabilities) and of the phenylephrine RR-SAP slope. Patients affected by PAF were characterized by a drastic decrease in total power of RR variability and by the absence of LFRR and LFSAP components. Moreover, HFRR, although largely predominant in its relative value, was also markedly reduced in its absolute value. Finally, the baroreceptive mechanisms appeared to be heavily impaired. In conclusion, PAF patients seem to be characterized by a complex alteration of neural mechanisms, which in addition to the signs of a sympathetic denervation include an impairment, at least functional, of the vagal modulation of heart rate.

Original languageEnglish
Pages (from-to)223-235
Number of pages13
JournalJournal of the Autonomic Nervous System
Issue number3
Publication statusPublished - Mar 2 1995


  • Baroreceptor sensitivity
  • Power spectrum analysis
  • Primary autonomic failure

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Neuroscience(all)


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