Autonomic Nervous System Monitoring of Patients with Excess Parasympathetic Responses to Sympathetic Challenges—Clinical Observations

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.