A MULTISCALE MODELLING APPROACH FOR DETAILED ANALYSIS OF FLOW THROUGH THE REALHEART VALVES

Maria Carnarius, Nimesh Singh, Nathaniel Kelly, Azad Najar, Pieper Ina Laura, Katharine Fraser

Research output: Contribution to journalMeeting abstractpeer-review

Abstract

Objectives: Prosthetic valves are integral to many displacement blood pumps used as Ventricular Assist Devices or Total Artificial Hearts (TAHs), such as Realheart TAH. Due to relatively fast flows, in the presence of abrupt corners, prosthetic valves have potential to exert high fluid shear stress on blood, and so cause haemolysis. Cavitation and regurgitation are potential issues which, if they occur, would exacerbate the blood damage. This project aimed to create numerical models of the Realheart valves which can be used to investigate the impact of design changes and operating conditions, on shear stress, washout and cavitation.

Methods: Two CFD models were created: (1) the left side of the Realheart including atrial chamber, mitral valve, ventricle chamber and aortic valve; and (2) a single valve within a tube. Both models used an immersed solid approach for the motion of the valve and valve leaflets. (1) Autodesk CFD was used with motion of the valve leaflets prescribed according to experimental data. Pressure boundary conditions at inlet (15 mm Hg) and outlet (70 mmHg) created an adverse pressure gradient to simulate vascular resistance. (2) Ansys CFX was used with flow driven motion of the valve leaflets, and flow rate from the linear displacement of the mitral valve in (1). A range of adverse pressure gradients were investigated.

Results: (1) The model has been created and is currently being used to assess differences in the flow field arising from differences in the orientation and location of the valves. Initial simulation results at 80BPM show that the orientation of the mitral valve can vary the peak fluid velocity by approximately 30% and the peak shear stress by over 25%.

Discussion: The two models have been used to investigate the prosthetic valves within the Realheart. Initial CFD results indicate the valve orientation can significantly influence the fluid dynamics. The models are currently being developed to incorporate washout, cavitation and haemolysis.
Original languageEnglish
JournalThe International Journal of Artificial Organs
Volume43
Issue number8
DOIs
Publication statusPublished - 18 Aug 2020

Cite this