The Prediction of Atherosclerosis Index Based on Photoplethysmograph

Table 1

PPG signal extraction features and formulas.

Number	Feature	Define	Formula
1	CT	Crest time	CT = t2
2	CTR	Crest time ratio	CTR = t2/T
3	K	Slope	Kslope = t1
4	PPT	Pulse wave transit time	PPT = t5
5	SI	Stiffness index
6	RI	Reflection index
7	EF	Ejection fraction
8	T	T is the pulsation period	See T in Figure 3
9	HR	Heart rate
10	K value	A PPG feature value	Shown (1)