Abstract
Introduction. The objective of the work is to evaluate the effect of blood rheological model on the results of mathematical modeling of direct steady-state flow through mechanical prostheses of heart valves.
Material and methods. Solid Works environment with Cosmos FloWorks application was selected for simulation of blood flow. 3D-solid-state models of left ventricular outflow tract and 3D models of mechanical prostheses of heart valves were created: “ATS”, “Carbomedics”, “Medtronic Advantage”, “Medtronic Hall”, “On-X”, “St. Jude Medical”, “Sorin Bicarbon” and “MedEng-2”. The valves were sized to a uniform calculated orifice diameter of 15 mm. Three rheological models of working fluid were adopted in simulation: water, simulation of Newtonian blood flow and non-Newtonian blood flow model of K. Perktold. The problems regarding direction of blood flow through valve housing ring (valve housing without leaflets) with orifice diameter of 15 mm and through mechanical valve prostheses with orifice diameter of 15 mm as well. In both cases the values of blood pressure changes Δp (mm Hg) and effective orifice area (EOA, mm2) were determined.
Results. The results of the assessment of effective orifice area for the prosthetic valve housing ring and valve prostheses peculiarly were acquired using СFD computer modeling of steady-state blood flow based on Newtonian and non-Newtonian blood rheological models. The obtained curves “EOA – Δp” clearly show the relationship between the calculated value of effective orifice area and rheological model and blood flow rate set up in stimulation. The estimated error of EOA measurement has been reported.
Conclusion. The effect of blood rheological model on the results of flow simulation at the flow rate of 5, 10, 15 and 25 l/min in different types of mechanical heart valve prostheses has been evaluated. It was established that it is possible to apply a simple Newtonian model for the blood at high values of flow rate whereas non-Newtonian model should be applied at low values.
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