Fluid–structure interaction modelling of a positive-displacement Total Artificial Heart

Joe Bornoff, Azad Najar, Libera Fresiello, Thomas Finocchiaro, Ina Laura Perkins, H S Gill, Andrew Cookson, Katharine Fraser

Research output: Contribution to journalArticlepeer-review

3 Citations (SciVal)

Abstract

For those suffering from end-stage biventricular heart failure, and where a heart transplantation is not a viable option, a Total Artificial Heart (TAH) can be used as a bridge to transplant device. The Realheart TAH is a four-chamber artificial heart that uses a positive-displacement pumping technique mimicking the native heart to produce pulsatile flow governed by a pair of bileaflet mechanical heart valves. The aim of this work was to create a method for simulating haemodynamics in positive-displacement blood pumps, using computational fluid dynamics with fluid-structure interaction to eliminate the need for pre-existing in vitro valve motion data, and then use it to investigate the performance of the Realheart TAH across a range of operating conditions. The device was simulated in Ansys Fluent for five cycles at pumping rates of 60, 80, 100 and 120 bpm and at stroke lengths of 19, 21, 23 and 25 mm. The moving components of the device were discretised using an overset meshing approach, a novel blended weak-strong coupling algorithm was used between fluid and structural solvers, and a custom variable time stepping scheme was used to maximise computational efficiency and accuracy. A two-element Windkessel model approximated a physiological pressure response at the outlet. The transient outflow volume flow rate and pressure results were compared against in vitro experiments using a hybrid cardiovascular simulator and showed good agreement, with maximum root mean square errors of 15% and 5% for the flow rates and pressures respectively. Ventricular washout was simulated and showed an increase as cardiac output increased, with a maximum value of 89% after four cycles at 120 bpm 25 mm. Shear stress distribution over time was also measured, showing that no more than [Formula: see text]% of the total volume exceeded 150 Pa at a cardiac output of 7 L/min. This study showed this model to be both accurate and robust across a wide range of operating points, and will enable fast and effective future studies to be undertaken on current and future generations of the Realheart TAH.

Original languageEnglish
Pages (from-to)5734-5748
Number of pages1
JournalScientific Reports
Volume13
Issue number1
DOIs
Publication statusPublished - 14 Apr 2023

Bibliographical note

J.B. PhD funded 50/50 from Scandinavian Real Heart AB and EPSRC (Reference: 2426107). The authors gratefully acknowledge the University of Bath’s Research Computing Group (http://doi.org/10.15125/b6cd-s854) for their support in this work.

Data availability
The datasets generated and/or analysed during the current study are not publicly available due commercial sensitivity but are available from the corresponding author on reasonable request

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