The role of the surrounding tissue in the propagation of waves through the arterial system.

A theoretical analysis of the flow in arteries is presented, taking into consideration the role played by the surrounding tissues in determining the speed of propagatoion and the damping of the blood pressure pulse. This study was undertaken (a) to exhibit a method of computing the flow properties with a more nearly accurate model, (b) to see if the displacement on the skin would be related to the arterial wall displacement, and hence to pressure, velocity and flow rate of blood in the artery, and if it is likely to be measurable. It was found that the pressure of the 'viscous' part in the surrounding tissue increases the pulse velocity and the damping of the wave over the values found by other models which considered only thick-walled elastic tubes with no surrounding tissue. This study also shows that measurements on the skin can provide information about changes in arterial circulation due to diseases such as: edema, arteriosclerosis and others where the Young's modulus for either the arterial wall or the surrounding tissues is altered.