Validity of Commonly Used Heart Rate Variability Markers of Autonomic Nervous System Function

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Research
• Biomedical Signal Analysis

Background:

• Concerns exist regarding the validity of several heart rate variability (HRV) measures.
• Despite these reservations, numerous studies continue to utilize these HRV metrics.

Purpose of the Study:

• To compare sympathetic HRV markers (LF, VLF) with electrodermal activity (EDA) during cognitive and orthostatic stress.
• To assess if LF reflects vagal-mediated baroreflex modulation.
• To evaluate parasympathetic HRV markers (RMSSD, HF) for quantifying vagal reactivity.

Main Methods:

• Comparison of HRV markers (LF, VLF, RMSSD, HF) with electrodermal activity (EDA).
• Assessment of autonomic nervous system reactivity under cognitive and orthostatic stress.
• Analysis of HRV under varying breathing conditions.

Main Results:

• No correlation was found between purported sympathetic HRV markers and electrodermal reactivity.
• LF reactivity correlated with RMSSD and HF reactivity during baroreflex modulation.
• RMSSD and HF indicated parasympathetic reactivity during normal breathing; RMSSD was superior when breathing changed.

Conclusions:

• LF and VLF do not represent cardiac sympathetic modulation; LF may indicate vagal baroreflex effects.
• HRV linear analysis is limited to assessing vagal influences on heart rate.
• HF should not be used as a vagal activity index during tasks requiring verbal responses due to potential respiratory distortion.