title: Cardiac autonomic dysfunction in patients with normal tension glaucoma: 24-h heart rate and blood pressure variability analysis.
abstract: OBJECTIVE
  To define parameters of autonomic nervous system activity in patients with normal tension glaucoma (NTG).
  
  
  METHODS
  Ambulatory 24-h ECG (Lifecard CF) and 24-h blood pressure (BP) monitoring (SpaceLab 90207-30) were carried out in 54 patients with NTG (44 women, mean age 59.7) and 43 matched control subjects (34 women, mean age 57.0). Heart rate variability time and frequency domain parameters (low frequency (LF), high frequency (HF) and LF/HF ratio), BP variability (BPV), diurnal and nocturnal BP variables were compared between study groups.
  
  
  RESULTS
  Patients with NTG demonstrated higher LF, LF/HF and lower HF values than control subjects for the 24-h, daytime and night-time periods. The mean 24-h, daytime and night-time LF/HF ratios were statistically higher in patients with glaucoma as compared to control subjects ((3.2±1.5 vs 2.2±0.8, p=0.0009), (3.5±1.7 vs 2.7±1.0, p=0.0173) and (2.6±1.7 vs 1.4±0.6, p=0.0001), respectively). There were no statistical differences in the mean BP during the whole day, daytime and night-time, and in BPV (10.4±1.9 vs 10.5±2.1, p=0.790) between study groups. No difference was also found in the percentage decrease in night-time mean BP (12.3% vs 13.6%, p=0.720). 'Dippers', 'non-dippers' and 'overdippers' with NTG showed significantly higher LF/HF ratio as compared to the same subgroups of control subjects.
  
  
  CONCLUSIONS
  The sympathovagal balance of autonomic nervous system in patients with NTG shifted towards sympathetic activity however with no change of 24-h pattern of BPV as compared to controls.
authors.affiliation: Department of Ophthalmology, Military Institute of Medicine, 128 Szaserów Str. 04-141 Warsaw 44, Poland. joanna.wierzbowska@gmail.com
authors.forename: Joanna
authors.initials: J
authors.lastname: Wierzbowska
authors.forename: Robert
authors.initials: R
authors.lastname: Wierzbowski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Stankiewicz
authors.forename: Brent
authors.initials: B
authors.lastname: Siesky
authors.forename: Alon
authors.initials: A
authors.lastname: Harris
mesh_terms: D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D057066:Low Tension Glaucoma / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology