KENKO TECHNOLOGY

Heart-Rate Variability (HRV)

HRV is a useful index for assessing human emotions due it’s connection and reflection by the ANS, thus make the HRV, using the analysis measures, a strong and valid objective tool for measuring human emotion.

Heart-Rate Variability (HRV) is the variation in time between consecutive heartbeats and is emerging as an objective measure of regulated emotional responding.

HRV evaluates the balancing act between the sympathetic nervous system (SNS, “fight or flight response”) and the parasympathetic nervous system (PNS, rest and digest).HRV measurements are also used to estimate other stress markers such as: respiration cycles, oxygen levels, physical activity, stress and recovery phases.

HRV analysis commonly categorized into the following domains:

Time-domain analysis

A frequency-based technique which parses from the ECG signal the quantity of HRV occurring at different frequencies (in hertz), and calculated as cycles per second.Spectral analysis has been done in short‐term laboratory studies, often standard 5‐minute ECG segments.

Three widely used components can be found in HRV power spectrum:LF (0.04-0.15 Hz): a low-frequency component that is mediated by both the SNS and PNSHF (0.15-0.4Hz): a high-frequency component mediated by the PNSLF/HF: LF to HF ratio that is used as an index of autonomic balance.

Figure 2 shows the power spectrum, a distribution of variance in heart rate at different frequencies.

Spectral-domain analysis:

Figure 1 shows a P wave, a QRS complex, and a T wave in the ECG. The P waverepresents atrial depolarization, the QRS represents ventricular depolarization,and the T wave reflects the rapid repolarization of the ventricle.

The R-R interval is the time interval between two R peaks (in ms) and is used to calculate heart rate.

In time domain analysis, the intervals between adjacent normal R waves (NN intervals) are measured over the period of recording. A variety of statistical variables can be calculated from the intervals directly and others can be derived from the differences between intervals.

SDNN: Standard deviation of NN intervals
SDANN: Standard deviation of the average NN interval computed across all 5-min recording segments
rMSSD: Square root of the mean of the squares of successive NN interval differences
NN50: The number of NN intervals differing by >50 ms from the preceding interval
pNN50: The percentage of intervals >50 ms different from preceding interval

SDNN during a 24‐hour period, is the most commonly used time domain measure of HRV

Figure 1. Idealized electrocardiograph segment representing two heartbeats. Waveforms are labeled with letters and correspond with specific electrophysiological events during a heartbeat. The interbeat interval is defined by the temporal distance between R-spikes, the waveforms corresponding to depolarization of the heart’s ventricles.

Figure 1. Idealized electrocardiograph segment representing two heartbeats. Waveforms are labeled with letters and correspond with specific electrophysiological events during a heartbeat. The interbeat interval is defined by the temporal distance between R-spikes, the waveforms corresponding to depolarization of the heart’s ventricles.

Figure 2. An example of a heart rate variability power spectrum obtained using the fastFourier transform on a 5-min recording obtained from a resting subject in supine position.

Figure 2. An example of a heart rate variability power spectrum obtained using the fastFourier transform on a 5-min recording obtained from a resting subject in supine position.

References

HRV

HRV Analysis

Heart-Rate Variability (HRV)

Science   >

GSR

Data Analysis