title: Assessment of the relationship between non-dipping phenomenon and heart rate turbulence.
abstract: BACKGROUND
  The aim of this cross-sectional study was to evaluate cardiac autonomic function by heart rate turbulence (HRT) indices in normotensive and hypertensive individuals with either non-dipper or dipper type circadian rhythm of blood pressure (BP).
  
  
  METHODS
  A total of 122 patients were allocated into four groups: normotensive/dipper, n = 33; normotensive/non-dipper, n = 31; hypertensive/dipper, n = 29; and hypertensive/non-dipper, n = 29. HRT indices (turbulence slope [TS] and turbulence onset [TO]) were calculated from 24-h ambulatory electrocardiographic recordings.
  
  
  RESULTS
  TS values were higher (TS = 10.0 ± 3.4 vs 8.0 ± 1.5, p = 0.004) and TO values were lower (TO = -2.9 [-3.6, -2.2] vs -2.0 [-2.3, -1.9], p = 0.037) in the dipper subgroup of normotensive cases than in the non-dipper subgroup of normotensive cases. Similarly, TS values were higher (TS = 8.4 ± 3.5 vs 6.2 ± 2.9, p = 0.012) and TO values were lower (TO = -2.1 [-3.4, -2.0] vs -1.6 [-1.9, -0.2], p = 0.003) in the dipper subgroup of hypertensive cases than in the non-dipper subgroup of hypertensive cases. Spearman's correlation analyses revealed a high positive correlation between percentage of dipping and TS (r = 0.600, p = 0.001) and a higher negative correlation between percentage of dipping and TO (r = -0.653, p = 0.001).
  
  
  CONCLUSIONS
  Blunting of the nocturnal fall in BP is associated with impaired HRT indices in both normotensive and hypertensive groups.
authors.affiliation: Department of Cardiology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
authors.forename: Levent
authors.initials: L
authors.lastname: Sahiner
authors.forename: Sercan
authors.initials: S
authors.lastname: Okutucu
authors.forename: Ugur Nadir
authors.initials: UN
authors.lastname: Karakulak
authors.forename: Kudret
authors.initials: K
authors.lastname: Aytemir
authors.forename: Sefik Gorkem
authors.initials: SG
authors.lastname: Fatihoglu
authors.forename: Ergun Baris
authors.initials: EB
authors.lastname: Kaya
authors.forename: Giray
authors.initials: G
authors.lastname: Kabakci
authors.forename: Lale
authors.initials: L
authors.lastname: Tokgozoglu
authors.forename: Hilmi
authors.initials: H
authors.lastname: Ozkutlu
authors.forename: Ali
authors.initials: A
authors.lastname: Oto
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D013997:Time Factors