Ultrasound echography capabilities in defining rheological properties of circulating blood

Objective: the research is aimed at studying the capabilities of ultrasound echography in defining rheological properties of circulating blood in different parts of vasculature in vivo in real hemodynamic situation. Ultrasound examinations of blood flow in different parts of arterial vasculature were performed on 586 male and female patients aged 20 to 85, with different cardiovascular pathologies. The examinations were made by linear probe, radiation frequency 3-9 MHz, with color “energy” and spectral doppler coding of blood flow and spectral impulse doppler sonography. The study showed new opportunities for ultrasound echography in defining a number of parameters characterizing rheological properties of blood such as thickness of shear layer of blood flow, crosssectional area of shear layer of blood flow, crosssectional area of axial blood flow, blood kinematic viscosity (ν), Womersley number (α), Reynolds number (Re), shearing stress: τ = V ν index of shift of the flow (ε). The study showed capabilities of visual examination and accurate measurement of thickness of shear layer of blood flow in any part of vasculature which open a prospect to use ultrasound echography as a new method of objective analysis of blood rheological properties in real hemodynamic situation (in vivo). Thickness of shear layer of blood flow can be considered a universal (visual and quantitative) criterion that characterizes local and regional hemorheologic properties. The number of parameters calculated on the basis of blood flow shear-layer thickness forms ultrasonic hemorheologic pattern which is an objective “complex dynamical” criterion in diagnosing of regional and local pathology of hemostasis system of circulating blood. The capability to differentiate shear (viscous) and axial (inertial) layers in blood flow structure allows to analyze hemodynamic effectiveness of the flow in any part of vasculature.