Pulse Related Changes in Electrical Impedance of Blood Vessels: Physical, Experimental and Modelling Aspects

Abstract

Abstract The paper presents the results of studies directed toward the determination of physical mechanisms and causal factors responsible for variations in the electrical impedance of the cardiovascular system. Experiments were carried out using the original hydrodynamic apparatus modelling different hemodynamic conditions, i.e., a pulsatile flow in a blood vessel of variable diameter, ramified pulmonary blood flows and the function of a cardiac valve. Computer-assisted signal processing techniques provided measurements of the active and capacitive components of the electrical conductivity with an error not exceeding 0.1%. Impedance values were analyzed for different vessel size and geometry, flow rate, temperature, concentration of ionic and dielectric components in some model biological fluids at different frequencies of the probing alternating current. It has been found that bioimpedance oscillations can be mainly attributed to the local modulations of the diameter of blood vessels such as the function of cardiac valves.