title: Power spectral components of heart rate variability in different types of cardiac remodelling in hypertensive patients.
abstract: BACKGROUND
  The aim of the study was to evaluate whether there are any significant differences in cardiac autonomic regulation in distinct types of hypertensive cardiac remodelling.
  
  
  METHODS
  We examined 86 patients with mild to moderate essential hypertension (EH). The parameters of left ventricle (LV) were measured by echocardiography: the diastolic mass normalized for body surface area (LVMI) and relative wall thickness (RWT). All patients were divided into three groups: normal LV geometry (23), concentric left ventricular hypertrophy (LVH) (29) and eccentric LVH (34). The control group included 30 age and sex-matched healthy volunteers. For calculation of heart rate variability (HRV) 512 RR intervals in supine rest and passive tilt were measured. Power spectral analysis with fast Furrier transform was used to obtain the total power, low frequency (LF) power (from 0.003 to 0.14 Hz), high frequency (HF) power (from 0.15 to 0.40 Hz) and sympathovagal index (SVI) as LF:HF ratio.
  
  
  RESULTS
  The parameters of HRV did not differ significantly among the groups studied. In the group with normal LV geometry there was observed a good response to tilt test resulting in an increase of SVI in three times (from 2.4 +/- 0.3 to 7.2 +/- 0.4), while in patients with both types of LVH there were no significant changes in SVI or even an inverse reaction to passive tilt. In the group with normal geometry patients with higher meanings of RWT had higher LF power (r = 0.52, p < 0.01), while in patients with LVH the increasement of LVMI and RWT was associated with reduction of HRV (rr = -0.43, -0.36, p < 0.05, respectively).
  
  
  CONCLUSIONS
  Heart rate variability is significantly reduced in essential hypertension and is also closely connected with cardiac structure and function. Patients with normal LV geometry are characterized by a preserved response to tilt test. LVH produce significant disturbances of autonomic regulation possibly due to lower sensitivity of cardiac adrenoreceptors independently of the LVH pattern.
authors.affiliation: Department of Faculty Therapy, St. Petersburg Pavlov State Medical University, 6/8 Lev Tolstoy st., St. Petersburg 197089, Russia. pynnonenpeterburg@mail.admiral.ru
authors.forename: A O
authors.initials: AO
authors.lastname: Konrady
authors.forename: O G
authors.initials: OG
authors.lastname: Rudomanov
authors.forename: O I
authors.initials: OI
authors.lastname: Yacovleva
authors.forename: E V
authors.initials: EV
authors.lastname: Shlyakhto
mesh_terms: D000328:Adult; D001794:Blood Pressure; D003971:Diastole; D004452:Echocardiography; D005260:Female; D018475:Head-Down Tilt; D006321:Heart / Q000502:physiology / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012146:Rest; D016683:Supine Position; D016277:Ventricular Function, Left / Q000502:physiology*