Autonomic Nervous System Monitoring of Patients with Excess Parasympathetic Responses to Sympathetic Challenges—Clinical Observations
Autonomic Nervous System Monitoring of Patients with Excess Parasympathetic Responses to Sympathetic Challenges—Clinical Observations
US Neurology, 2010;5(2):62-6
Abstract
A common assumption regarding the autonomic nervous system is that one branch either opposes the other or does not respond during physiological challenges. Recently, this assumption has been challenged based on clinical observations of unprovoked parasympathetic (P) excess (PE) during sympathetic (S) stimulation, an abnormal response. Over a three-year period, serial autonomic profiling of 1,340 patients was performed using the P and S method, which yields independent measures of P and S activity obtained from time–frequency analyses of respiratory activity and heart rate variability (ANX 3.0, ANSAR Medical Technologies, Inc., Philadelphia, PA). Within this cohort, patients with PE reported symptoms of sleep difficulties, poor peripheral circulation, general malaise, depression, frequent headache or migraines, gastrointestinal upset, and dizziness when standing. However, they demonstrated normal heart rate and blood pressure and no other apparent causes for their symptoms. The results of this study highlight the clinical effects of PE and indicate that, depending on patient history, carvedilol may be effective for patients with cardiovascular disease (CVD) and low-dose anticholinergics for patients without CVD. In cases where end-organ effects are not yet presented, patients may be weaned from therapy once PE is resolved.
Keywords
Autonomic nervous system (ANS), parasympathetic, parasympathetic excess/challenge, sympathetic, sympathetic excess/challenge, postural change, valsalva, beta-adrenergic antagonist, beta-blocker, cardiovascular disease, hypertensive, autonomic imbalance
Disclosure: Samanwoy Ghosh-Dastidar, PhD, is an employee of ANSAR. Joe Colombo, PhD, is an employee and co-owner of ANSAR. The other authors have no conflicts of interest to declare.
Received: December 3, 2009 Accepted: January 21, 2010
Correspondence: Joe Colombo, PhD, 240 S Eighth Street, Philadelphia, PA 19107. E: joe@ans-hrv.com
Non-invasive autonomic nervous system (ANS) assessment is often based on physiological challenges, such as the Valsalva maneuver and head-up postural change for the sympathetic nervous system (SNS) and deep breathing for the parasympathetic nervous system (PSNS). A common assumption about the ANS is that the predominant response is from stimulation of one ANS branch, and the opposing branch decreases its response or does not respond to the challenge. Partially responsible for this assumption is an incomplete understanding of the ANS.
In the past, measures of autonomic function have been based solely on heart rate variability (HRV), which yields mixed assessment of parasympathetic (P) and sympathetic (S) activity.1 Therefore, these measures cannot provide complete information about the health of the ANS. Separate tests for S activity and P activity based on these measures also yield incomplete information because neither test accounts for the independent actions of the two ANS branches. The dynamic nature of the ANS and the continuous PSNS and SNS interactions dictate the requirement for simultaneous, independent measures of P and S activity. Only with such measures can the patient’s autonomic activities, including responses to disease and common medications, be understood.
The failure of measures based solely on HRV2–4 can be attributed to a fundamental mathematical conundrum. Basic algebra dictates that a system (e.g. ANS) with two independent components requires two independent measures to be fully characterized. HRV alone is onesuch independent measure with multiple dependent measures. A solution to this conundrum was introduced in the 1996 Circulation Special Report, standardizing measures based solely on HRV.1 The solution was validated by the Massachusetts Institute of Technology (MIT) and Harvard.5–8 It has recently been implemented for clinical use.9,10 The solution involves the introduction of a second measure of autonomic function—respiratory activity (RA). Analyzing RA concurrently with HRV offers two independent measures of the ANS and thus satisfies the fundamental algebraic requirement establishing independent, simultaneous measures of P and S activity. Analysis of RA concurrent with HRV is named the ‘P and S method’ in this article.
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Autonomic nervous system (ANS), parasympathetic, parasympathetic excess/challenge, sympathetic, sympathetic excess/challenge, postural change, valsalva, beta-adrenergic antagonist, beta-blocker, cardiovascular disease, hypertensive, autonomic imbalance, cranial nerves peripheral nervous system, spinal cord central nervous system, somatic Autonomic nervous system, vagus nerve Autonomic nervous system, acetycholine Autonomic nervous system,
