Autonomic Nervous System Testing (ANS)
The autonomic nervous system (ANS) regulates physiologic processes, such as blood pressure, heart rate, body temperature, digestion, metabolism, fluid and electrolyte balance, sweating, urination, defecation, sexual response, and other processes. Regulation occurs without conscious control, i.e., autonomously. The ANS has two major divisions: the sympathetic and parasympathetic systems. Many organs are controlled primarily by either the sympathetic or parasympathetic system, although they may receive input from both; occasionally, functions are reciprocal (e.g., sympathetic input increases heart rate; parasympathetic decreases it).
The sympathetic nervous system is catabolic and activates fight-or-flight responses. Thus, sympathetic output increases heart rate and contractility, bronchodilation, hepatic glycogenolysis and glucose release, BMR (basal metabolism rate), and muscular strength; it also causes sweaty palms. Less immediately-life-preserving functions (e.g., digestion, renal filtration) are decreased.
The parasympathetic nervous system is anabolic; it conserves and restores. Gastrointestinal secretions and motility (including evacuation) are stimulated, heart rate is slowed, and blood pressure decreases.
Disorders of the ANS can affect any system of the body; they can originate in the peripheral or central nervous system and may be primary or secondary to other disorders. Symptoms suggesting autonomic dysfunction include orthostatic hypotension, heat intolerance, nausea, constipation, urinary retention or incontinence, nocturia, impotence, and dry mucous membranes. If a patient has symptoms suggesting autonomic dysfunction, cardiovagal, adrenergic, and sudomotor tests are usually done to help determine severity and distribution of the dysfunction.
Cardiovagal innervation testing evaluates heart rate response to deep breathing and to the Valsalva maneuver, via electrocardiogram rhythm strip. If the ANS is intact, heart rate varies with these maneuvers; the ratio of longest to shortest R-R interval (Valsalva ratio) should be 1.4 or greater.
Vasomotor adrenergic innervation testing evaluates response of beat-to-beat blood pressure to the head-up tilt and Valsalva maneuver. The head-up tilt shifts blood to dependent parts, causing reflex responses. The Valsalva maneuver increases intrathoracic pressure and reduces venous return, causing blood pressure changes and reflex vasoconstriction. In both tests, the pattern of responses is an index of adrenergic function.
Autonomic nervous system (ANS) testing, including parasympathetic function (cardiovagal innervation), sympathetic adrenergic function (vasomotor adrenergic innervation).
DanTest is diagnostic tool to evaluate symptoms of vasomotor instability for any of the following:
- Diagnose the presence of autonomic neuropathy in a patient with signs or symptoms suggesting a progressive autonomic neuropathy, including: Diabetic neuropathy, Amyloid neuropathy, Sjogren’s syndrome, Idiopathic neuropathy, Pure autonomic failure, Multiple system dystrophy.
- Evaluate the severity and distribution of a diagnosed progressive autonomic neuropathy;
- Differentiate the diagnosis between certain complicated variants of syncope from other causes of loss of consciousness;
- Evaluate inadequate response to beta blockade in vasodepressor syncope;
- Evaluate distressing symptoms in the patient with a clinical picture suspicious for distal small fiber neuropathy in order to diagnose the condition;
- Differentiate the cause of postural tachycardia syndrome;
- Evaluate change in type, distribution or severity of autonomic deficits in patients with autonomic failure;
- Evaluate the response to treatment in patients with autonomic failure who demonstrate a change in clinical exam;
- Diagnose axonal neuropathy or suspected autonomic neuropathy in the symptomatic patient;
- Evaluate and diagnose sympathetically maintained pain, as in reflex sympathetic dystrophy or causalgia; or
- Evaluate and treat patients with recurrent unexplained syncope to demonstrate autonomic failure.
Heart Rate Variability (HRV) is a physiological function whereby the time interval between heart beats varies. These variations in heart rate reflect the quality of cardiovascular autonomic function. Autonomic function or function of the autonomic/visceral nervous system regulates involuntary action (eg. respiration, digestion) of the intestines, heart, smooth muscle, and glands. This function is divided into two physiologically and anatomically distinct, mutually antagonistic subsystems: the sympathetic nervous system and the parasympathetic nervous system.
DanTest systems provide HRV testing which enable physicians to monitor the activity of both the sympathetic and parasympathetic branches of the autonomic nervous system (ANS) in order to accurately assess the state of a patient's autonomic function.
DanTest provides a two-pronged approach to patient evaluation. Firstly, DanTest is able to detect specific types of autonomic dysfunction which can consequently be linked to a multitude of clinical diagnoses. Secondly, DanTest can be utilized for thorough, comprehensive assessments and physiological monitoring which provide physicians with a detailed and thorough patient appraisal which can often be overlooked in standard evaluations.
The wide range of clinical applications for DanTest makes it principally different from all other classes of diagnostic devices. DanTest allows the physician to thoroughly investigate modalities:
The significance of the DanTest method in the development of HRV assessment:
- Assessment of resting autonomic balance
- Assessment of reaction of the ANS on orthostatic intervention
- Assessment of autonomic reaction during Valsalva maneuver and deep breathing
- Sympathetic and Parasympathetic autonomic balance correction
In the past, autonomic function could only be approximately assessed by the following three parameters: Autonomic Balance (Vegetative Homeostasis), Sympathetic Prevalence, Parasympathetic Prevalence. The criteria used for evaluating these parameters were clinical and laboratory findings therefore assessment of the autonomic function was labor intensive and not always feasible.
The introduction of HRV analysis revolutionized ANS assessment and opened new doors for its theoretical application. Making practical use of this important scientific discovery, however, required deriving a quantitative relationship between SNS and PSNS from the spectral function.
HRV analysis is based upon measuring variability in heart rate; specifically, variability in intervals between R waves - "RR intervals". These RR intervals are then analyzed by spectral (as in DanTest) or some other form of mathematical analysis. Such mathematical analysis generates multiple parameters; time domain and frequency domain. The problem of SNS-PSNS quantification is in reducing all possible variations of these multiple parameters to a quantitative relationship between the SNS and PSNS. For many years, this issue has been the central obstacle in HRV analysis.
DanTest is the first and only system to solve the problem of SNS-PSNS quantification. This technological breakthrough is achieved by using proprietary algorithms and a pioneering approach. The algorithms used by DanTest have been developed and tested exhaustively for over 30 years. Studies of efficacy and accuracy have involved over 50,000 patients to ensure success.
The result of this in depth research is objective and reliable evaluations of ANS state during rest, during Orthostatic (seated-to-standing) testing and during the Valsalva maneuver combined with deep breathing. DanTest analyses are far-reaching and highly sophisticated. Consequently, DanTest is the only method that enables precise recognition and classification of up to 100 ANS states while providing corresponding descriptions of each.
Until the development of the DanTest method, there was no practical means of assessing ANS independently outside of a research laboratory. DanTest brought laboratory analyses into the physician's office and became the first and only system to provide a quantitative interpretation of HRV spectral function as well as a qualitative analysis of the resulting parameters.
The goal and achievement of the DanTest research team is in providing physicians worldwide with a reliable office device capable of multiple clinical applications including the assessment of risk in cardiovascular diseases, objective assessment of benefit for cardiac and orthopedic intervention, and the quantification of drug effect on the autonomic function.
Heart Rate Variability (HRV) is a measure of the variation in beat-to-beat intervals in heart rate. Heart rate variability analysis is a powerful tool in assessment of the autonomic function. It is accurate and reliable, yet simple to measure (i.e. noninvasive) and quick to process.
HRV analysis measures neuro-cardiac function which reflects heart-brain interactions and autonomic nervous system dynamics. The autonomic nervous system is involved in the function of virtually every organ system and clinical manifestations of autonomic dysfunction are involved in just about every disease. As a result, HRV analysis is used as a screening and monitoring tool in many disease processes.
Higher variations in the heart rate lead to greater heart rate variability which indicates good health and well-balanced autonomic function (sympathetic and parasympathetic nervous systems). In contrast, steadier heart rate leads to lower heart rate variability which indicates an imbalance in the autonomic function and implies the presence of physiological malfunction.
DanTest delivers laboratory analyses to the physician's office, enabling professionals to assess patient health conveniently and reliably. Applications include:
- Verifying the effectiveness of treatment and intervention
- Monitoring overall patient health
- Screening the general population
- Identifying various health issues such as heart palpitations, pain management, sleep apnea, anxiety, stress, psychological disorders, asthma, and neurological conditions
- Examining for CAN (Cardiac Autonomic Neuropathy) and DAN (Diabetes Autonomic Neuropathy)
- Measuring the Sympathetic Nervous System's predominance in cases such as Metabolic Syndrome, Hypertension or Heart Failure
- Screening for unfavorable in the absence of clinically apparent health situations
Reduction in HRV leads to adverse prognostic implications in cardiovascular, neurological and other metabolic conditions such as diabetes and obesity.
Short term HRV analysis can identify patients at high risk for premature death within cardiac risk stratification.
HRV test procedures provide supplemental monitoring and optimized detection of early signs of adverse effects of any medications.
In general population studies, a deterioration of HRV patterns can be a useful indicator of endangered health situation related to adverse events.
Physical and pharmaceutical interventions to increase HRV lead to better individual prognosis.
Significant Clinical Applications
DanTest assessments provide supplemental monitoring and optimized detection of cardiovascular, neurological and metabolic conditions associated with a multitude of adverse health events. The DanTest product range provide physicians and health professionals with convenient, cost-effective solutions for clinical testing and optimized patient assessment. Applications include the following:
- Beta-Blocker Responsiveness
- Cardiovascular Autonomic Neuropathy (CAN)
- Diabetic Autonomic Neuropathy (DAN)
- Cardiac Arrhythmias
- Congestive Heart Failure
- Sleep Apnea
- Sudden Death
- Peripheral Vascular Diseases
- Ortostatic Hypotension
- Circulation Problems
- Pain Management
- Neurological Conditions
- Chronic Regional Pain Syndrome
- Parkinson's Disease
- Psychological Conditions
- Other Hidden Diseases
Autonomic Balance Studies -Heart Rate Variability Assessment has acquired exceptional popularity over the last few years. Nowadays, the main stream medical associations around the world accept ANS-HRV studies as one of the best predictors of specific and non-specific health risk. Scientific and Clinical studies have established its usefulness in almost all branches of medicine.
How It Helps Your Patients:
- Evaluation of current health situation - symptoms, medications and therapy reactions;
- Assessment of possible adequacy of the recovery process;
- Initiation of Physician’s focus to treat the onset of chronic situations or severity of the diseases;
- Evaluation of the prognosis and treatment outcomes;
- Identification of abnormalities in cardiovascular, cerebrovascular system and overall health assessment;
- Blood circulatory status – age of blood vessels based on arterial elasticity, peripheral circulatory status, organic/functional abnormality of the blood vessels;
- Prediction and progression of arteriosclerosis in cases such as Obesity, Hypertension, Hyperlipidemia and Diabetes;
- Useful as a health barometer;
How It Helps You:
- Monitoring current health of the individual patient closely;
- Verifying the efficacy of current treatment protocol and intervention;
- Examining patients for CAN and DAN – Cardiac Autonomic Neuropathy and Diabetes Autonomic Neuropathy;
- Measuring the Metabolic Syndrome, Hypertension, Heart Failure;
- Predicting burn-out syndrome, anxiety, depression, psychological conditions;
- Exploring Asthma, COPD, Palpitations, Pain management, Sleep apnea PLUS;
- Optimization of treatment for each individual patient;
- Immediate reports – qualitative, quantitative and graphic analysis and results of ANS balance, cardiovascular, stress, fitness and overall health assessment for comparison with patient case history and necessary procedural actions;
- Efficient patient-centered multiple symptoms treatment management;