title: Daily Dysfunction of Autonomic Regulation Based on Ambulatory Blood Pressure Monitoring in Patients with Neurally Mediated Reflex Syncope.
abstract: BACKGROUND
  The onset of neurally mediated reflex syncope (NMRS) is associated with dysfunction of the autonomic regulatory system. Yet relatively little is known about the daily conditions of the autonomic regulation system in patients with NMRS. This study elucidated characteristics of daily autonomic function using ambulatory blood pressure monitoring (ABPM) and evaluated the utility of ABPM for NMRS diagnosis.
  
  
  METHODS
  Patients with syncope underwent the head-up tilt test (HUT) (80°, 30 minutes). If no syncope occurred, the HUT was repeated with drug loading. ABPM was performed on a different day.
  
  
  RESULTS
  The enrolled subjects were 152 consecutive patients with syncope and 12 controls. Sixty-four patients with other diseases related to autonomic dysfunction were excluded. HUT with/without drug loading was positive in 40 patients (Group P) and negative in 48 patients (Group N). The average systolic blood pressure (SBP) in daytime was lower in Groups P and N than in the control group (Group C) (P < 0.05). The average diastolic blood pressure in daytime was also lower in Group P than in Group C (P < 0.05). The average standard deviation-SBP at nighttime was higher in Groups P and N than in Group C (P < 0.05). In heart rate variability analysis, Group P had higher high frequency normalized unit in daytime than Groups C and N (P < 0.05, P < 0.1). Low frequency/high frequency was lower in Group P than in Group N in both daytime and nighttime (P < 0.1, P < 0.05).
  
  
  CONCLUSIONS
  This study suggests that patients with NMRS present with daily vagal hyperactivity and sympathetic dysfunction. ABPM may support the diagnosis of NMRS.
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Onishi
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Yoshino
authors.initials: Y
authors.lastname: Minoura
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Chiba
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Onuki
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Adachi
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Asano
authors.affiliation: Division of Cardiology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Youichi
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D018660:Blood Pressure Monitoring, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012018:Reflex; D013575:Syncope / Q000209:etiology / Q000503:physiopathology*; D018667:Tilt-Table Test
keywords: ambulatory blood pressure monitoring; autonomic dysfunction; hemodynamics; syncope