Abstract

As stress becomes very important, there were many attempts to evaluate stress. Among many methods, there is a way to measure stress by observing physiologic response, such as using activity of pituitary-adrenal axis and autonomic nervous system. Task force of the European Society of Cardiology and The North American Society of pacing and Electrophysiology made standard methods of measurement, interpretation, and clinical use of HRV. The measurement of HRV is divided to Time domain methods and frequency domain methods. Time domain methods use heart rate, SDNN, RMSSD, and frequency domain methods use total power, VLF (very low frequency), LF (low frequency), HF (high frequency). The SDNN is the standard deviation of all the normal R-R intervals in the entire 24-hour ECG recording. Along with stability of cardiovascular system, it is used as strong index of ability of autonomic nervous system. RMSSD is the root mean square of successive differences between the normal heart beat It is used as estimating the high frequency beat-to-beat variations in HRV which provides an estimate of the parasympathetic regulation of the heart. HF reflects parasympathetic or vagal activity, and LF can reflect both sympathetic and parasympathetic activity. However in most cases LF reflects more of sympathetic activity. Total power provides information of activity of autonomic nervous system along with sympathetic nervous system. The high number of LF/HF ratio means that sympathetic nervous system increased or parasympathetic nervous system decreased. This ratio can be used to calculate the balance of autonomic nervous system. As the measurement of HRV is not invasive and quantitative, it will be used widely in study and practice of stress. (Korean J Str Res 2005;13:59∼63)

• Keywords: Stress, Measurement of stress, Heart rate variadility, Autonomic nervous system