Numerical Washout Study of a Pulsatile Total Artificial Heart

Sonntag, Simon J.; Kaufmann, Tim; Büsen, Martin; Laumen, Marco; Graf, F.; Linde, Torsten; Steinseifer, Ulrich

doi:10.5301/ijao.5000306

Cited by 25 publications

(31 citation statements)

References 42 publications

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“…Volume of fluid (VOF) modelling, as developed by Sonntag et al [22], was used to determine LV washout. The VOF model is generally used for interface tracking of immiscible fluids.…”

Section: Methodsmentioning

confidence: 99%

Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs

et al. 2016

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BackgroundImplantation of a rotary blood pump (RBP) can cause non-physiological flow fields in the left ventricle (LV) which may trigger thrombosis. Different inflow cannula geometry can affect LV flow fields. The aim of this study was to determine the effect of inflow cannula geometry on intraventricular flow under full LV support in a patient specific model.MethodsComputed tomography angiography imaging of the LV was performed on a RBP candidate to develop a patient-specific model. Five inflow cannulae were evaluated, which were modelled on those used clinically or under development. The inflow cannulae are described as a crown like tip, thin walled tubular tip, large filleted tip, trumpet like tip and an inferiorly flared cannula. Placement of the inflow cannula was at the LV apex with the central axis intersecting the centre of the mitral valve. Full support was simulated by prescribing 5 l/min across the mitral valve. Thrombus risk was evaluated by identifying regions of stagnation. Rate of LV washout was assessed using a volume of fluid model. Relative haemolysis index and blood residence time was calculated using an Eulerian approach.ResultsThe inferiorly flared inflow cannula had the lowest thrombus risk due to low stagnation volumes. All cannulae had similar rates of LV washout and blood residence time. The crown like tip and thin walled tubular tip resulted in relatively higher blood damage indices within the LV.ConclusionChanges in intraventricular flow due to variances in cannula geometry resulted in different stagnation volumes. Cannula geometry does not appreciably affect LV washout rates and blood residence time. The patient specific, full support computational fluid dynamic model provided a repeatable platform to investigate the effects of inflow cannula geometry on intraventricular flow.

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“…Volume of fluid (VOF) modelling, as developed by Sonntag et al [22], was used to determine LV washout. The VOF model is generally used for interface tracking of immiscible fluids.…”

Section: Methodsmentioning

confidence: 99%

Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs

et al. 2016

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“…In the literature, to the best of the authors' knowledge, biological valves have not been considered when simulating an artificial ventricle. There are, however, a few CFD studies with mechanical valves (18)(19)(20)(21)(22)(23), whose leaflets move as rigid bodies under a prescribed roto-translational displacement in the CFD simulations.…”

Section: Discussionmentioning

confidence: 99%

“…Others studies considered the disk valve motion but only in a 2D model . The FSI studies, like the one described by Avrahami et al , adopted an arbitrary Lagrangian–Eulerian (ALE) kinematic approach, with a moving fluid grid according to the structure displacement; it reproduced accurately the hemodynamics near the structures, to estimate for example the blood damage indexes like wall shear stress and particle residence time . It is also known that the ALE formulation guarantees very accurate results near the interface between the solid structures and the fluid with respect to the fixed grid approaches, for example, the immersed boundary method, which is an alternative relatively less computationally expensive than the FSI approach.…”

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confidence: 99%

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Numerical Approach to Study the Behavior of an Artificial Ventricle: Fluid–Structure Interaction Followed By Fluid Dynamics With Moving Boundaries

Luraghi

Castilla

et al. 2018

Artificial Organs

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Heart failure is a progressive and often fatal pathology among the main causes of death in the world. An implantable total artificial heart (TAH) is an alternative to heart transplantation. Blood damage quantification is imperative to assess the behavior of an artificial ventricle and is strictly related to the hemodynamics, which can be investigated through numerical simulations. The aim of this study is to develop a computational model that can accurately reproduce the hemodynamics inside the left pumping chamber of an existing TAH (Carmat‐TAH) together with the displacement of the leaflets of the biological aortic and mitral valves and the displacement of the pericardium‐made membrane. The proposed modeling workflow combines fluid–structure interaction (FSI) simulations based on a fixed grid method with computational fluid dynamics (CFD). In particular, the kinematics of the valves is accounted for by means of a dynamic mesh technique in the CFD. The comparison between FSI‐ and CFD‐calculated velocity fields confirmed that the presence of the valves in the CFD model is essential for realistically mimicking blood dynamics, with a percentage difference of 2% during systole phase and 13% during the diastole. The percentage of blood volume in the CFD simulation with a shear stress above the threshold of 50 Pa is less than 0.001%. In conclusion, the application of this workflow to the Carmat‐TAH provided consistent results with previous clinical studies demonstrating its utility in calculating local hemodynamic quantities in the presence of complex moving boundaries.

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“… 8 – 13 As far as the device operation is concerned, the phenomena of coagulation, activation of platelets, haemolysis and cavitation, which may occur in the device, are the most important. 14 – 18 Due to a very complex flow structure in VADs, engineering skills and intuition are not sufficient to design a VAD reducing risk of thrombosis and haemolysis caused by the device itself. Therefore, numerical flow simulations, supported by experimental verification, are of great importance in the prediction of the flow structure.…”

Section: Introductionmentioning

confidence: 99%

Methods for determination of stagnation in pneumatic ventricular assist devices

et al. 2018

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Background:A pneumatic paediatric ventricular assist device developed at the Foundation of Cardiac Surgery Development, Zabrze, equipped with valves based on J. Moll’s design, with later modifications introduced at the Institute of Turbomachinery, Lodz University of Technology, was tested numerically and experimentally. The main aim of those investigations was to detect stagnation zones within the ventricular assist device and indicate advantages and limitations of both approaches.Methods:In the numerical transient test, a motion of the diaphragm and discs was simulated. Two different methods were used to illustrate stagnation zones in the ventricular assist device. The flow pattern inside the chamber was represented by velocity contours and vectors to validate the results using images obtained in the laser particle image velocimetry experiment.Results:The experimental light-based method implied problems with proper illumination of regions in the wall vicinity. High-resolution flow data and other important parameters as stagnation regions or flow patterns in regions not accessible for light in the particle image velocimetry method are derived in the numerical solution. However, computations of a single case are much more time-consuming if compared to a single experiment conducted on a well-calibrated stand.Conclusion:The resulting main vortexes in the central part of the pump chamber and the velocity magnitudes are correlated in both methods, which are complementary and when used together offer better insight into the flow structure inside the ventricular assist device and enable a deeper analysis of the results.

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Numerical Washout Study of a Pulsatile Total Artificial Heart

Cited by 25 publications

References 42 publications

Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs

Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs

Numerical Approach to Study the Behavior of an Artificial Ventricle: Fluid–Structure Interaction Followed By Fluid Dynamics With Moving Boundaries

Methods for determination of stagnation in pneumatic ventricular assist devices

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