Fig. 1
An example of an approximated model of conceptual PPG waveform and vessel wall movements. a An example of approximated model of a normotensive waveform (SBP 115 mmHg, subject no. 9, b pre-hypertensive waveform (SBP 137 mmHg, subject no. 11). A, B, C, D, A′, B′, C′ and D′ are classified by vessel wall movement, and Pi, Pm and Po mean input, measurement spot and output pressure respectively. c Early-systole (period A), d late-systole (period B), (e) early-diastole (period C), f late-diastole and start of reflected wave (period D), g early-reflection and Po > Pi in normotensive case (period A′ and B′), h late-reflection (period C′ and D′), multiple reflected waves are arrived in order, period C′ and D′ are represented alternately