title: Diurnal characteristics of heart rate variability in patients with sarcoidosis.
abstract: BACKGROUND
  The aim of this study was to evaluate autonomic nervous system function by measuring heart rate variability (HRV) in patients with sarcoidosis without known cardiac manifestations.
  
  
  METHODS
  The study comprised 61 participants, including 31 patients with sarcoidosis without known cardiac manifestations and 30 healthy volunteers. All participants underwent echocardiographic examination, 12-channel electrocardiography (ECG), and 24-h Holter monitoring. HRV parameters were determined and compared between the groups.
  
  
  RESULTS
  There were no differences between groups with regard to age, body mass index, systolic and diastolic blood pressure, or heart rate at the time of admission. In the time domain analyses, the 24-h, daytime, and night-time standard deviations of all normal-to-normal R‑R interval (SDNN) values were significantly lower in patients with sarcoidosis than those in the controls. The frequency domain analyses showed that 24-h and daytime low-frequency (LF) values, 24-h, daytime, and night-time high-frequency (HF) values were significantly lower in the patient group compared with the control group, whereas the night-time LF/HF ratio was significantly higher.
  
  
  CONCLUSIONS
  Although Holter ECG is not a diagnostic tool for cardiac sarcoidosis, the HRV parameters, especially the night-time LF/HF values, may demonstrate increased sympathetic activation in patients with sarcoidosis.
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey. dr.ziyaeddin@outlook.com.
authors.forename: Z
authors.identifier: http://orcid.org/0000-0001-5034-298X
authors.initials: Z
authors.lastname: Aktop
authors.affiliation: Faculty of Medicine, Department of Pulmonary Medicine, Bülent Ecevit University, Zonguldak, Turkey.
authors.forename: H
authors.initials: H
authors.lastname: Tanrıverdi
authors.affiliation: Faculty of Medicine, Department of Pulmonary Medicine, Bülent Ecevit University, Zonguldak, Turkey.
authors.forename: F
authors.initials: F
authors.lastname: Uygur
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: İşleyen
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey.
authors.forename: B
authors.initials: B
authors.lastname: Kalaycı
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey.
authors.forename: Y C
authors.initials: YC
authors.lastname: Gursoy
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey.
authors.forename: T
authors.initials: T
authors.lastname: Karabağ
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Aydın
authors.affiliation: Faculty of Medicine, Department of Cardiology, Bülent Ecevit University, 67600, Kozlu/Zonguldak, Turkey.
authors.forename: I
authors.initials: I
authors.lastname: Akpınar
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology; D009202:Cardiomyopathies / Q000175:diagnosis / Q000503:physiopathology; D002940:Circadian Rhythm / Q000502:physiology*; D004452:Echocardiography; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012507:Sarcoidosis / Q000175:diagnosis / Q000503:physiopathology; D017565:Sarcoidosis, Pulmonary / Q000175:diagnosis / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology
keywords: Autonomic dysfunction; Diurnal rhythm; Heart rate variability; Holter monitoring; Sarcoidosis