Table 1.

Overview of different approaches to measure pulse wave velocity focusing on their principles, advantages, and possible disadvantages.

Approach	Principle	Advantage	Disadvantages	Reference
Tonometry (direct)	Time-delay between two pressure sensors placed on the skin along an arterial vessel	Accurate and direct detection of PWV	Prone to artifacts; sensors must be placed correctly; affected by any movements	[22, 23, 24, 25, 26, 27]
Tonometry (indirect)	Time-delay between two light-sensors (photoplethysmography) on the skin along an arterial vessel	Accurate and indirect detection of PWV; less prone to artifacts	Indirect measurement of volume changes; sensors must be placed correctly; affected by stray light	[28, 29, 30]
Doppler ultrasound	Doppler effect	Real-time observation; depiction of specific arterial segment	Highly dependent on observer’s skills, transducer placement, and angle of wave entrance	[31, 32, 33, 34, 35, 36]
Oscillometer analysis	Fluctuations in pressure in the cuff during blood pressure measurement	Easy to perform; quick measurement	Potentially inaccurate, prone to movement artifacts	[37, 38, 39, 40, 41]
MRI	High-resolution images of the arterial walls	Observer independent; high reproducibility	Low accessibility; high costs	[42, 43, 44, 45, 46, 47, 48, 49]
PAT/PTT	PWV estimation using surrogate parameters	Easy to detect; possible use in wearable devices for long-term studies	Need for transfer functions, indirect and potentially inaccurate PWV measurements	[50, 51, 52, 53]

PWV, pulse wave velocity; MRI, magnetic resonance imaging; PAT, pulse arrival time; PTT, pulse transit time.