Nonlinear Pulse Wave Reflection at an Arterial Stenosis

Abstract

A simple model is presented to analyze the effect of stenoses of different severities in a long elastic tube or artery on the pressure and flow-rate wave forms incident upon them. Wave propagation in the undisturbed tube is taken to be linear; nonlinearity arises from the quadratic dependence of stenosis pressure drop on flow rate. Before the model can be applied in practice, important physiological questions must be answered; e.g.: (a) Can the incident wave form and mean proximal pressure be regarded as given input? (b) Is the mean flow rate given, or does the peripheral resistance remain constant? Results are given on the assumption that the answer to (a) is yes. The principal conclusion is that the input impedance spectrum of a stenosed artery depends strongly on the incident waveform, as well as on the severity of the stenosis and on the distance from it at which measurements are made. There is good qualitative agreement with the results of experiments and of other models.