The importance of HRV is that it is controlled by the autonomic nervous system and therefore is a window into its function. The autonomic nervous system — composed of the sympathetic nervous system and the parasympathetic nervous system automatically influences the visceral organs, smooth muscle such as the blood vessels and glands and obviously the heart.
The second component of HRV besides the time domain is the spectral analysis. The ECG is broken down into very specific frequency band widths that correspond to specific functions. Low frequency, for example has to do with sympathetic nervous system and high frequency has to do with parasympathetic nervous system function.
According to Dr. Michael Kessler, HRV is a reflection of the autonomic nervous system which controls 90% of the body's functions...advanced HRV can reflect our evolutionary biology and where we are today, in terms of our ability to adapt to multiple stressors. This specialized HRV gives us a quantitative view of our adaptive capabilities and predicts how all of our regulatory systems are working inside or outside a specific zone.
This computerized system allows the practitioner to quickly monitor the rhythmic patterns of the heart rate by extracting data from an electro-cardio signal. The HRV is used to follow indices of the autonomic nervous system, neuro-hormonal system, psycho-emotional state, brain electrical activity, meridian and chakras in relation to the endocrine system.
A scan takes only 5 minutes (300 heartbeats) using ECG wrist leads to measure the HRV.