MEASUREMENT OF HEART-RATE-VARIABILITY

Heart rate variability (HRV) is a measure of autonomic nervous system balance/imbalance. Measurement and analysis of HRV can be classified i nto time domain analysis and frequency domain analysis. Time domain an alysis is a general measure of autonomic nervous system balance and is based on altered versions of the measurement of the standard deviatio n of heart period, defined in terms of the sinus R-R intervals over ti me. There are six commonly used time domain measurements: SDANN, 24-hr SD, SD, RMSSD, RR50, and % RR50. Frequency domain analysis uses eithe r autoregressive or fast Fourier transform techniques to delineate par asympathetic (high-frequency components) from sympathetic (low-frequen cy components) of autonomic control. This study explores the clinical applications of HRV with respect to respiratory sinus arrhythmia, exer cise, mortality, sudden cardiac arrest, myocardial infarction, and con gestive heart failure.