As society becomes more health conscious and as the search continues for a more balanced lifestyle, this focus has recognized that there are direct links between the health and balance of the autonomic nervous system (ANS) and cardiovascular mortality. Sudden cardiac deaths have risen and alarmingly in even the most healthy of individuals. Questions have arisen as to whether there is any link between the propensity for lethal arrhythmias and increased sympathetic or reduced vagal activities. As answers are sought, efforts have been made to develop measures or markers of autonomic activity and the balance or imbalance therein. One of these markers is heart rate variability (HRV). This marker measures the variations in heart rate and is calculated by analyzing the beat-to-beat intervals from ECG or arterial pressure tracings. A heart beat occurs when a set of special cells continuously distribute electrical pulsations throughout the heart muscle in specialized pathways. The muscle’s contractions are coordinated between both ventricles and atriums. The development of various diseases is examined, treatment plans are derived and evaluations made to determine potential outcomes and aid in a treatment protocol. ANS, the portion of the nervous system that manages all the body’s physiological functions, plays a vital part in the body’s survival, providing constant control over the heart’s activity.

ANS Function In Relation to Health and Disease

The ANS controls virtually every system in the human body. It is necessary for the ANS to be in proper balance in order to achieve good health, thereby allowing individuals to adapt to changes in their environment. Any type of ANS dysfunction reduces an individual’s longevity, compromises their quality of life and often precedes disease. Many "normal" people live with issues or have lifestyles that adversely affect ANS balance. Stress has a debilitating effect on almost every bodily system and has a significant impact on ANS balance, an impact that in most instances is asymptomatic. Lifestyles that include prolonged and continuous stress can create ANS imbalance and leaves the individual vulnerable to illness and disease that can be directly attributable to such imbalance. By constantly monitoring and evaluating ANS function and balance, it is possible to minimize ANS risk factors, delay the onset of ANS neuropathy including heart disease and diabetics and minimize the changes of contracting diseases such as hypertension, orthostasis and vascular disease. If ANS dysfunction is caught early, more aggressive therapy treatments can be implemented sooner. HRV, one of the noninvasive techniques for evaluating ANS status, is an important indicator of an individual’s ability to effectively react to life’s stress and everyday pressures.

Heart Rate Variability Norms - Importance of Having Specific Sets

In order to understand ANS and to perform properly HRV assessments, monitoring of both the sympathetic and parasympathetic systems must be performed. Due to the fact that individual patient’s physiological differences result in differences in response to disease and differences in response to therapy, a baseline must be established by which to compare the HRV assessment results. Without such baseline norms, judgments could be made that would put the individual at risk for incorrect diagnoses, too aggressive of therapy or inaccurate conclusions. HRV control groups should be established and evaluated against specific individuals, thereby enabling a more aggressive treatment plan to be designed that will complement the specific needs of a patient.

Heart Rate Variability - Automated Measurement

Because HRV represents one of the most promising markers for ANS evaluation and the relative ease in measurement, it has gained in popularity over the past two decades. Many commercial devices now provide an automated measurement of HRV, and health professionals and clinicians have a simple tool for both research and clinical studies.