title: Posture and Gender Differentially Affect Heart Rate Variability of Symptomatic Mitral Valve Prolapse and Normal Adults.
abstract: BACKGROUND
  Heart rate variability (HRV) has been shown to be a useful measure of autonomic activity in healthy and mitral valve prolapsed (MVP) subjects. However, the effects of posture and gender on HRV in symptomatic MVP and normal adults had not been elucidated in Taiwan.
  
  
  METHODS
  A total of 118 MVP patients (7 males, 39 ± 7 years old; and 111 females, 42 ± 13 years old) and 148 healthy control (54 males, 28 ± 4 years old; and 94 females, 26 ± 6 years old) were investigated. The diagnosis of MVP was confirmed by cross-sectional echocardiography. A locally developed Taiwanese machine was used to record the HRV parameters for MVP and control groups in three stationary positions. Thereafter, the HRV time-domain parameters, and the frequency-domain parameters derived from fast Fourier transform or autoregressive methods were analyzed.
  
  
  RESULTS
  The MVP group showed a decrease in time domain parameters and obtunded postural effects on frequency domain parameters moreso than the control group. Though the parasympathetic tone was dominant in female (higher RMSSD, nHF and lower nLF vs. male), the sympathetic outflow was higher in MVP female (lower SDNN, NN50 and higher nLF vs. normal female). While the parasympathetic activity was lower in male, sympathetic outflow was dominant in MVP male (lower nHF and higher nLF vs. normal male).
  
  
  CONCLUSIONS
  Both MVP female and male subjects had elevated levels of sympathetic outflow. The obtunded postural effects on frequency domain measures testified to the autonomic dysregulation of MVP subjects.
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsinchu; ; Division of Cardiology;
authors.forename: Chien-Jung
authors.initials: CJ
authors.lastname: Chang
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsinchu;
authors.forename: Ya-Chu
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsinchu; ; Department of Cardiac Surgery, Tungs' Taichung Metroharbor Hospital, Taichung;
authors.forename: Chih-Hsien
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Jen-Chi General Hospital;
authors.forename: Ing-Fang
authors.initials: IF
authors.lastname: Yang
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsinchu; ; Graduate Institute of Medical Informatics, Department of Internal Medicine, Taipei Medical University and Hospital, Taipei, Taiwan.
authors.forename: Ten-Fang
authors.initials: TF
authors.lastname: Yang
keywords: Arrhythmia; Autonomic nerve system; Heart rate variability; Mitral valve prolapse