Spectral Analysis of Heart Rate Variability

Frequency domain analysis of heart rate variability (HRV) is used to identify and measure the principal rhythmical _uctuations that characterise, even during resting conditions, the RR interval time series and contain physiological information [1]. Clinical interest for this non-invasive methodology originates from the fact that spectral analysis of HRV has been proven to provide important and accurate information on sympathetic and vagal modulation of sinus node in normal subjects and in patients with a variety of organic heart diseases [1–5] as well as on arrhythmic and total cardiac mortality after myocardial infarction [1,6–8]. Spectral analysis of HRV can be performed on RR interval time series derived from short-term ECG recording (3–5 minutes) under controlled conditions as well as from 24-hour Holter monitoring. Simultaneous analysis of other signals, such as respiratory activity and arterial blood pressure, can also be implemented to obtain a more complete evaluation of beat-to-beat variability of the cardiovascular system and of its autonomic control [1,4].