Theory

There is well known that decreasing of Parasympathetic activity directly correspond with the damage of Parasympathetic receptors after any pathology. As result the goal of Autonomic Function testing is to recognize the stage of pathological developments by assessments of level of Parasympathetic activity. 
Assessment of Sympathetic Nervous system activity clinically makes sense to see the stress level and acute of some problems for instance; acute of infarct of the myocardium, acute of intoxication and others. Decrease of Sympathetic activity in most of the cases related with degenerative joint diseases for elderly people and beta-blockers overdozage. But clinical issues of different Sympathetic activities level can exist only in case of pathological decreasing of Parasympathetic function. In case of positive Parasympathetic activity different Sympathetic level make sense only as a normal physiology issues.
Another aspect of Autonomic Function testing based on Heart Rate Variability analysis is Risk Stratification of Sudden Cardiac Arrest. It's the most efective if combained with appropriate clinical and/or ECG evidence like T-wave alternance, but some times even without it.

Quantitative Assessment of ANS based on heart rate variability analysis has been the subject of intensive research for the past four decades. Currently multiple facets of its theoretical and practical value encourage numerous cutting-edge investigational studies in both basic and clinical research. However, for many years this method has remained the privilege of research laboratories and was not accessible to medical practitioners, and only recently was recognized for its effectiveness in clinical use by the FDA, AAMI, ANSI, a number of health organizations and insurance companies. 

Intellewave technology is unique in its ability to automatically differentiate between Sympathetic and Parasympathetic influences on R-R intervals variability regulation mechanisms by using proprietary patented method based on Artificial Intelligence theory. Such of method did not require any other sorce of information than R-R intervals variability.  

Hence, we included here an overview of theoretical and practical aspects of ANS assessment based on HRV, provided by courtesy of Alexander Riftine,PhD, a distinguished investigator recognized worldwide for his contribution in heart rate variability research.

This theoretical overview covers results of Dr. Riftine’s multiple investigational projects, uses statistical data accumulated over the period of 25 years, and incorporates findings of other published research studies in Heart Rate Variability analysis and ANS assessment. To illustrate typical cases of ANS reaction to controlled exercises, the author selected results from patients tested with Intellewave system, as this system is currently on the U.S. medical market.