Noninvasive Pulse Measurements for Cardiovascular Health Monitoring and Diagnoses

Arterial pulses reflect the physiological and pathological conditions of the human body, especially cardiovascular conditions. Traditional Chinese Medicine (TCM) has used the pulse measurement at the radial artery for illness diagnoses over thousands of years although their technique by touch feelings for the pulses is too subjective. This chapter presents contemporary and more objective methods for pulse measurements and analyses. It first summarizes current noninvasive pulse measurement methods, including tonometry, photoplethysmography (PPG), ultrasound Doppler flowmetry and a variety of flexible pressure sensors. Then analyses for the collected pulse waveforms are described for extracting the characteristic parameters and how they are correlated to the cardiovascular conditions. The enhanced classification methods by AI/ML are also presented for efficiently analyzing the pulse waveform datasets obtained from healthy subjects and those with cardiovascular and other chronic diseases such as type 2 diabetes. Finally, mathematical models ranging from the lumped parameter model (0-dimensional, 0-D) to more complex 1-D and 3-D models are introduced to relate the pulse variables (e.g., pressure, velocity, displacement) to the arterial wall mechanical properties, blood density and viscosity, geometrical and structural distributions of artery trees in the cardiovascular system as well as cardiac outputs.