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Age is an important determinant of heart rate variability (HRV) in healthy individuals. The incidence of arrhythmia is high in patients with mitral valve prolapse (MVP). However, the correlation of HRV in patients with MVP in different age groups is not well established. We presumed that increasing age would be prospectively associated with declining HRV measurement in MVP. Sixty patients with MVP and 120 control individuals were included and underwent 24 h HRV analysis. No significant difference was found in all parameters calculated in the time domain or in the frequency domain between the two groups. However, as patients' age increased, a significant time domain (SDNN, RMSSD, NN50, and pNN50) decline was found in the MVP group, but not in the control group. This suggests that patients with MVP may have autonomic nervous system involvement that increases the risk of arrhythmia and heart disease with increasing age. [ABSTRACT FROM AUTHOR]

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.

Objective: One of the major causes of death in end-stage renal disease (ESRD) patients under maintenance hemodialysis (HD) is ventricular arrhythmias (VA). Heart rate variability (HRV) has been claimed to be related to disturbance of autonomic nervous system and therefore a predictor for VA occurrence. The purpose of this study is to evaluate the relationship between the HRV parameters and electrolytes before and after hemodialysis in ESRD patients., Methods: There were 23 ESRD patients recruited for the study. Electrolytes for the analysis are Ca+2, P+3, Na+, K+, Cl-. Single lead electrocardiographic signal was recorded for five minutes and the HRV parameters (time-domain) were then derived by a Taiwanese CheckMyHeart machine. Time-domain parameters used were SDNN, RMSSD, NN50. SAS version 8.2 was used for the statistical analysis and paired student t test was adapted to evaluate the statistical significance of their changes. Pearson's partial correlation coefficients were also derived from the same software., Results: All electrolytes except chloride changes before and after hemodialysis were shown to be statistically significant analyzed by paired Student's test. Body weight changes significantly reduced from 57.57+/-6.78 kg to 55.26+/-9.92 kg (p<0.001) after the hemodialysis. Time-domain HRV parameters were shown to increase significantly after hemodialysis. There was no correlation between electrolytes changes and time - domain and frequency-domain HRV parameters after hemodialysis., Conclusions: 1. All electrolyte changes before and after HD were statistically significant. 2. HRV parameters (SDNN, NN50 and rMSSD) significantly increased after HD. 3. QTc and QT intervals decreased after HD. 4. Partial correlation analysis revealed that there was no statistically significant correlation between electrolytes changes and the HRV parameters.