Wave Travel and Velocity
The heart generates pressure and flow waves. Because of the elasticity of the aorta and the major conduit arteries, the pressure and flow waves are not transmitted instantaneously to the periphery, but they propagate through the arterial tree with a certain speed, which we call wave speed or pulse wave velocity (c). In analogy to waves created by stone dropped in a lake, the waves seen on the surface travel with a speed that is measured by the time it takes for the disturbance (wave) to cover a certain distance. The distance traveled by the wave over the time delay gives the wave speed, as schematically shown in the Figure in the box. Also, in analogy with the stone dropped in the lake, the wave transmission takes place even in the absence of blood flow and is not related to the velocity of the blood. When a stone is dropped in a river, the waves superimpose on the water flow, and the wave fronts traveling downstream go faster than the wave fronts that move upstream. In other words, the velocity of the blood adds to the wave speed. However, since blood flow velocity is much smaller (cm/s) than wave velocity (m/s) this effect is usually neglected.
KeywordsPhase Velocity Pulse Wave Velocity Wave Speed Flow Wave High Pulse Pressure
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