On the transfer function characterization of blood flow. A simulation study

An analysis is made of the transfer function (TF) of heart-common-femoral blood flow, in order to test the plausibility of simple mathematical models proposed in the literature for clinical use as well as the physical significance of their parameters. The results show that: (1) it is necessary to limit greatly the frequency range considered (generally no more than 10 Hz) in order to have acceptable fits with simple models (characterized by no more than four zeros or poles); (2) the aortic-flow-common-femoral-flow TF is described well by at least three poles; (3) the aortic-pressure-common-femoral-flow TF is described well by at least one zero and four poles; and (4) finding a precise physical meaning of zeros and poles, as done for example in the Laplace transform method, is rather complicated.<>