title: Impairment in cardiac autonomic regulation preceding arterial hypertension in humans: insights from spectral analysis of beat-by-beat cardiovascular variability.
abstract: BACKGROUND
  Subjects in the upper-normal range of arterial pressure have an excess cardiovascular risk, which suggests that other factors, such as impaired autonomic regulation, might be implicated. This study was designed to assess whether noninvasive markers of cardiac and vascular autonomic regulation might already be altered in subjects with high-normal arterial pressure levels.
  
  
  RESULTS
  We performed an observational study on a population comprising 300 subjects of both sexes with arterial pressure ranging from 90/60 to 210/120 mm Hg, who were divided into 3 groups (each n=100) with average systolic pressures of 103, 133, and 163 mm Hg. Autonomic regulation was inferred from spectral analysis of RR interval and systolic arterial pressure variability, considering rest and stand-induced changes, to account for sympathetic excitatory components. Significant alterations in markers of sinoatrial regulation (increased low-frequency normalized units, reduced high-frequency normalized units, and alpha-index) were already apparent in subjects in the second tertile, ie, those with arterial pressure within normal limits. Markers of vascular regulation instead showed significant alterations in the third (hypertensive) tertile. In response to standing, changes in markers of sinoatrial modulations were gradually reduced, whereas those of vascular regulation were increased. A tight link between progression of arterial pressure and the continuum of changes in autonomic markers as shown by simple correlation analysis appeared strongly affected by age and was spread across many spectral analysis-derived variables. Hypertensive autonomic dysregulation was particularly apparent in the youngest group.
  
  
  CONCLUSIONS
  RR-variability parameters might prove useful to assess, with longitudinal studies, the mechanistic role of autonomic impairment in the increased risk of prehypertensive conditions.
authors.affiliation: Centro di Ricerca sulla Terapia Neurovegetativa, University of Milano, Milano, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Lucini
authors.forename: Giuseppe Sandro
authors.initials: GS
authors.lastname: Mela
authors.forename: Alberto
authors.initials: A
authors.lastname: Malliani
authors.forename: Massimo
authors.initials: M
authors.lastname: Pagani
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D017704:Baroreflex; D015415:Biomarkers / Q000032:analysis; D001794:Blood Pressure; D018450:Disease Progression; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000294:innervation* / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011187:Posture; D012016:Reference Values; D012306:Risk
chemical_list: D015415:Biomarkers