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

Area of Science:

• Biomedical Engineering
• Cardiovascular Engineering

Background:

• End-stage biventricular heart failure necessitates advanced interventions when transplantation is not feasible.
• Total Artificial Hearts (TAH) serve as critical bridge-to-transplant devices.
• The Realheart TAH employs a positive-displacement pumping technique with mechanical valves to mimic native heart function.

Purpose of the Study:

• To develop a computational fluid dynamics (CFD) simulation method for positive-displacement blood pumps.
• To investigate the hemodynamic performance of the Realheart TAH across various operating conditions.
• To validate the CFD model against in vitro experimental data.

Main Methods:

• Utilized CFD with fluid-structure interaction (FSI) in Ansys Fluent to simulate the Realheart TAH.
• Employed overset meshing for moving components and a novel blended weak-strong coupling algorithm for FSI.
• Implemented a custom variable time stepping scheme and a Windkessel model for physiological pressure response.
• Validated simulation results against a hybrid cardiovascular simulator.

Main Results:

• The CFD model demonstrated good agreement with in vitro flow rate and pressure data (max RMSE of 15% and 5%, respectively).
• Simulated ventricular washout increased with cardiac output, reaching 89% at 120 bpm and 25 mm stroke length.
• Shear stress analysis indicated minimal areas exceeding 150 Pa at 7 L/min cardiac output.

Conclusions:

• The developed CFD model is accurate and robust for simulating TAH hemodynamics.
• This simulation approach eliminates the need for pre-existing in vitro valve motion data.
• The model facilitates efficient future investigations of current and next-generation Realheart TAH devices.