The response involves the viscoelastic properties of the microvessel wall, which undergo variations in case of some cardiovascular diseases, e.g. in arteriosclerosis, and are strongly nonlinear as functions of the phase of the vessel i.e. being dilated, constricted or relaxed (Wiederheilm, C.A. (1964), Viscoelastic properties of relaxed and constricted arteriolar walls. 3rd European Conference on