Comparison of HRV analysis methods during Orthostatic Challenge: HRV with respiration or without?

Abstract

Heart Rate Variability (HRV) analysis has become an important tool in assessing human Autonomic Nervous System (ANS) activity in recent years. Orthostatic challenge is one of the most common tests to detect ANS dysfunction. In this study we looked at the changes in ANS activity of normal subjects to orthostatic challenge and compared the results of 3 different HRV analysis methods: Time-Domain Methods, HRV spectral analysis without respiratory analysis (RA) and with RA. Although all three methods have indicated an increase in sympathetic activity and a decrease in parasympathetic activity from baseline to stand, the only significant increase in sympathetic activity was observed in HRV with RA method. Additional information from RA enables isolating the sympathetic and parasympathetic branches in HRV signals and therefore reflects ANS changes more accurately. On the other hand, sympathetic and parasympathetic power may not be separated properly if respiration-dependent fluctuations in HRV are ignored. It is expected that the differences between methods would be very clear with low respiratory rates. However, we focused on studies with normal respiratory rates and have also found significant differences among the methods.

Open‐label pilot study: Non‐invasive vagal nerve stimulation improves symptoms and gastric emptying in patients with idiopathic gastroparesis

“…AFT was conducted using the ANX 3.0 (ANSAR Medical Technologies Inc). The ANX is a non‐invasive, digital, real‐time, heart rate variability and respiratory variability‐based monitor of the autonomic nervous system (ANS) . Three leads are used to capture EKG & respiratory signals.…”

“…The ANX is a non-invasive, digital, real-time, heart rate variability and respiratory variability-based monitor of the autonomic nervous system (ANS). 16 Three leads are used to capture EKG & respiratory signals. The ANX measures the ANS by detection and recording variations in the R-R, or beat-to-beat, interval and respiratory activity.…”

Low-frequency power of heart rate variability is not a measure of cardiac sympathetic tone but may be a measure of modulation of cardiac autonomic outflows by baroreflexes

“…Considering that LF power is influenced by respiration-related changes in cardiovagal outflow, it has been suggested that accounting for respiratory influences on LF power improves the accuracy of power spectral analysis of HRV in assessment of cardiac sympathetic tone (Aysin et al , 2007; Colombo et al , 2008). The ANSAR ANX 3.0 system (ANSAR Medical Technologies Inc., Philadelphia, PA) is the only commercially available device that makes this adjustment.…”

(r)Alpha Lipoic Acid Is a Safe, Effective Pharmacologic Therapy of Chronic Orthostatic Hypotension Associated with Low Sympathetic Tone

“…Using the ANX-3.0 Autonomic Monitor (ANSAR Medical Technologies, Inc., Philadelphia, PA), sympathetic-(S) and parasympathetic (P)-activity were computed simultaneously and independently based on concurrent, continuous, time frequency analysis of respiratory activity, and heart rate variability. [22][23][24][25][26][27] P activity measured as the respiratory frequency area (RFa) is defined as the spectral power within a 0.10 Hzwide window centered on the fundamental respiratory frequency in the heart rate variability spectrum. Fundamental respiratory frequency is identified as the peak spectral mode from time-frequency analysis of respiratory activity.…”