Embedded System Based on an ARM Microcontroller to Analyze Heart Rate Variability in Real Time Using Wavelets

Table 1

Parameters of the analysis HRV.

Domain	Description	Symbol	Units	Biological mean
Time	Mean between IBI interval		ms
	Mean heart rate		BPM
	Standard deviation of NN intervals	SDNN	ms	Estimate of overall HRV
	Measure the mean of standard deviation of intervals RR in windows of 5 minutes	iSDNN	ms
	Measure the standard deviation of the mean of the intervals RR in windows of 5 minutes	SDANN	ms
	Root mean squared of successive differences	RMSSD	ms	Short term component
	Percentage of intervals that differs more than 50 ms	pNN50	%
	Standard deviation of the heart rate		BPM
	Maximum time between IBI interval		ms
	Minimum time between IBI interval		ms
Frequency	Low frequency power	LF		Sympathetic nervous System activity
	High frequency power	HF		parasympathetic nervous System activity
	Ratio between low and high frequency	LF/HF		Sympathovagal balance
	Low frequency normalized	LFn	n.u
	High frequency normalized	HFn	n.u
Non linear	Poincare	SD1, SD2	ms	Term variability
Geometric (time domain)	Triangular index	RRTrin		Estimate of overall HRV
	Triangular Interpolation index	TINN

BPM(beats per minute), ms (milliseconds), (milliseconds squared), n.u. (normalized units), %(percent).