**5.1 What HRV is**

150 Modern Telemetry

SRV-2W is prepared for analysis of heart rate variability (HRV). I describe detail of the HRV in the next session. Breafly, this software detects R waves and calculated the R-R interval tachogram as the raw HRV in sequence order as shown in Fig. 7. Lorentz plots are also able

From this tachogram, the average and instantaneous power spectra are obtained by the fast Fourier transform as shown in raight and left of Fig. 8, respectively. The software calculates

Fig. 8. Examples of average power spectrum (left) and 75 instantaneous power spectra

For further analysis of ECGs such as RR-QT relationship, software for Bootstrap method can apply after analyzing all of the waves. This software is useful to detect QT prolongation induced by drugs. Moreover, software for signal average electrocardiogram is developed to

Fig. 7. Tachogram of the R-R interval (left) and example of Lorentz plots.

many index of values of HRV as shown in Fig. 8.

**4.4 SRV-2W** 

to display.

(right) in mouse.

**4.5 Other applications** 

detect ventricular late potential.

Heart rate being regulated by autonomic nervous system and endocrine system, is known to be affected with changes in postures, with exercise, with changes in psychological states. But heart rate is also known to fluctuate around the mean heart rate even in a stable condition. For example, when we inhale heart rate rises and when we exhale heart rate drops. This fluctuation of heart rate is known as respiratory sinus arrhythmia, and it occurs because burst rate at the sino atrial node changes according to respiration cycle. This kind of rhythmic fluctuation of the heart rate under stable condition, brought about by naturally occurring physiological perturbations such as respiration, blood pressure, and thermoregulation, is recognized as HRV. Considering that the principle systems involved in regulating the heart rate are mainly the sympathetic and parasympathetic nervous system, it has been suggested that the analysis of HRV could lead to noninvasive assessment of the tonic autonomic regulation of the heart rate.
