title: Endothelial Function and Cardiovascular Autonomic Activity in Neurally Mediated Syncope.
abstract: OBJECTIVE
  The aim of this study was to investigate endothelial function and cardiovascular autonomic activity in patients with neurally mediated syncope (NMS).
  
  
  METHODS
  Patients with a typical history of NMS were divided according to the result of a head-up tilt (HUT) test. There were 25 patients each in the HUT-positive (HUT+), HUT-negative (HUT-) and control groups. Flow-mediated dilation (FMD) and 24-hour ambulatory electrocardiography (AECG) were performed before the HUT tests.
  
  
  RESULTS
  The HUT+ group had a significantly higher FMD than that of the HUT- group and the control group (8.8 ± 3.3 vs. 6.4 ± 2.9%, p = 0.006, and 8.8 ± 3.3 vs. 5.7 ± 2.2%, p = 0.001, respectively). On a 24-hour AECG, the parasympathetic indexes of time domain, such as rMSSD and the pNN50, were significantly higher in the HUT+ group than in the HUT- group (39.0 ± 9.6 vs. 31.6 ± 9.6 ms, p = 0.016, and 16.5 ± 8.1 vs. 10.2 ± 7.2%, p = 0.002, respectively) and the control group (39.0 ± 9.6 vs. 28.9 ± 9.6%, p = 0.001 and 16.5 ± 8.1 vs. 8.7 ± 6.7%, p = 0.001, respectively). High-frequency spectra (parasympathetic activity) of the frequency domain showed similar results.
  
  
  CONCLUSIONS
  Not only parasympathetic activity, but also endothelial function may affect the results of HUT tests in patients with NMS.
authors.affiliation: Cardiovascular Division, Department of Internal Medicine, Hallym University Medical Center, Anyang, Republic of Korea.
authors.forename: Kyoung-Ha
authors.initials: KH
authors.lastname: Park
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Han
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Kim
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Jo
authors.forename: Sung-Ai
authors.initials: SA
authors.lastname: Kim
authors.forename: Woo Jung
authors.initials: WJ
authors.lastname: Park
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D010275:Parasympathetic Nervous System / Q000503:physiopathology*; D056910:Republic of Korea; D019462:Syncope, Vasovagal / Q000503:physiopathology*; D018667:Tilt-Table Test; D013997:Time Factors; D055815:Young Adult