Wave Travel and Pulse Wave Velocity

Abstract

Waves generated by the heart travel down the aorta and major conduit arteries. These waves are pressure waves, flow or velocity waves or diameter waves. The ratio of the distance Δx, and the time it takes for the foot of the wave to travel over this distance, Δt, gives the wave speed or pulse wave velocity, PWV=Δx/Δt. The same wave speed applies to pressure, flow and diameter waves, and by using the foot of the waves reflections play a minor role. The wave speed depends on vessel size and the elastic properties of the arterial wall. In the aorta of a healthy subject the wave speed is typically 4–5 m/s. In stiff aortas, having a low compliance the wave speed may be two times higher, implying a four-fold decrease in compliance. The wave speed in peripheral arteries is higher than in central arteries since the wall thickness is higher and the diameters are smaller.