Abstract
Introduction
The Realheart®, a total artificial heart developed by Scandinavian Real Heart, mimics the mechanics of the native heart by translation of an atrioventricular (AV) plane. Past numerical models of the Realheart® were not flow-driven but relied on prescribed motion of AV and semilunar (SL) valves. The objective was to develop a new modelling strategy, combining computational fluid dynamics and fluid-structure interactions that generalised the pumping mechanics of the Realheart®, using only the essential and most challenging modelling aspects.
Methods
A fluid cylinder containing two bileaflet mechanical heart valves, representing the AV (upstream) and SL (downstream) valves (fig 1a) was modelling in Fluent (Ansys Inc). A restriction (fig 1b) represented the resistance of the downstream vasculature. The Navier-Stokes equations were solved assuming Newtonian rheology. Overset meshing allowed for a refined leaflet boundary (fig 1c). The 6DOF solver computed the leaflets' rotation, whilst the AV overset mesh zone underwent vertical sinusoidal translation, achieving rotation and translation of the AV valve.
The SL valve opened at 0.15 s as fluid was pushed through the domain by the AV valve, and closed at 0.43 s, due to backflow (fig 2). Fluttering occurred upon SL valve opening, due to high pressures caused by downward AV motion. When the SL valve fully opened, fluid followed the leaflet motion, moving from the cylinder wall towards the centre, forming a faster flowing central region (figure 1 d).
Conclusions
A modelling strategy has been successfully developed that defines AV plane translation and AV/SL valve rotation. Further work will replace the constriction with a Windkessel model to capture physiological conditions and improve modelling flexibility. Additional studies will be used to understand the interplay between stroke parameters, and efficiency and valve leakage.
The Realheart®, a total artificial heart developed by Scandinavian Real Heart, mimics the mechanics of the native heart by translation of an atrioventricular (AV) plane. Past numerical models of the Realheart® were not flow-driven but relied on prescribed motion of AV and semilunar (SL) valves. The objective was to develop a new modelling strategy, combining computational fluid dynamics and fluid-structure interactions that generalised the pumping mechanics of the Realheart®, using only the essential and most challenging modelling aspects.
Methods
A fluid cylinder containing two bileaflet mechanical heart valves, representing the AV (upstream) and SL (downstream) valves (fig 1a) was modelling in Fluent (Ansys Inc). A restriction (fig 1b) represented the resistance of the downstream vasculature. The Navier-Stokes equations were solved assuming Newtonian rheology. Overset meshing allowed for a refined leaflet boundary (fig 1c). The 6DOF solver computed the leaflets' rotation, whilst the AV overset mesh zone underwent vertical sinusoidal translation, achieving rotation and translation of the AV valve.
The SL valve opened at 0.15 s as fluid was pushed through the domain by the AV valve, and closed at 0.43 s, due to backflow (fig 2). Fluttering occurred upon SL valve opening, due to high pressures caused by downward AV motion. When the SL valve fully opened, fluid followed the leaflet motion, moving from the cylinder wall towards the centre, forming a faster flowing central region (figure 1 d).
Conclusions
A modelling strategy has been successfully developed that defines AV plane translation and AV/SL valve rotation. Further work will replace the constriction with a Windkessel model to capture physiological conditions and improve modelling flexibility. Additional studies will be used to understand the interplay between stroke parameters, and efficiency and valve leakage.
Original language | English |
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Publication status | Published - 10 Jun 2021 |
Event | ASAIO 66th Annual Conference, 2021 - DC Hilton Hotel, Washington, DC, USA United States Duration: 10 Jun 2021 → 13 Jun 2021 |
Conference
Conference | ASAIO 66th Annual Conference, 2021 |
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Country/Territory | USA United States |
City | Washington, DC |
Period | 10/06/21 → 13/06/21 |