Investigation of unsteady flow in a model of a ventricular assist device by numerical modelling and comparison with experiment

König, Carola S.; Clark, C.; Mokhtarzadeh‐Dehghan, M.R.

doi:10.1016/s1350-4533(98)00084-8

Cited by 23 publications

(18 citation statements)

References 14 publications

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“…A direct comparison of the current results with the Brunel VAD results should be treated with caution, because of the differences in flow forcing between the two cases (piston-driven vs. diaphragm-driven flows). Although a sinusoidal pressure function was applied at the entrance of the water chamber, the diaphragm displacement deviated slightly from the sinusoidal waveform, due to pressure wave distortion as it moves through the water chamber (18).This deviation shows up when comparing the maximum cross-sectional averaged Reynolds numbers at the end of the inlet/ outlet tubes in the blood chamber, which was 3300 for the Brunel University VAD (2) and 4085 in the present simulations. This difference, along with differences in pressure magnitude, can account for the differences in velocity magnitudes shown in Fig.…”

Section: Blood Flow With Interacting Walls 875mentioning

confidence: 81%

“…The VAD used in this work is an idealized diaphragm‐type device, consisting of two hemispherical chambers, each with a diameter of 140 mm, separated by an elastic circular diaphragm. This geometry is based on a simpler VAD model studied at Brunel University (1–3), in which blood was driven into and out of a single hemispherical chamber by a hemispherical piston with prescribed motion. To be consistent with the Brunel VAD, the present model length scale is roughly two times that of a typical VAD, such as the Berlin VAD, which has a length scale of 80 mm (5).…”

Section: Methodsmentioning

confidence: 99%

“…The solid is meshed using nine-node mixed interpolation of tensorial component (MITC) shell elements on an unstructured grid. Blood is assumed to be an incompressible Newtonian fluid with a density of 1105 kg/m 3 and a viscosity of 4.66 ¥ 10 -3 kg/m·s, both chosen to match the values used in the Brunel VAD studies (2). The flow in the VAD is assumed to be laminar.…”

Section: Blood Flow With Interacting Walls 871mentioning

confidence: 99%

“…Pulsatile VADs generally consist of a flexible blood chamber or a rigid blood chamber with a flexible diaphragm. Previous simulations of such devices have generally disregarded FSI effects (1–3). Zhang and Hisada (4) performed FSI simulations of blood flow in a cylindrical VAD with a circular diaphragm in the middle and a single inlet/outlet tube on each end.…”

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confidence: 99%

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Numerical Simulations of Blood Flow in Artificial and Natural Hearts With Fluid–Structure Interaction

et al. 2008

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This article describes two ongoing numerical studies of fluid-structure interaction in the cardiovascular system: an idealized pulsatile ventricular assist device (VAD), consisting of two fluid chambers separated by a flexible diaphragm; and blood flow and heart wall motion during passive filling of a canine heart. Simulations have been performed for the VAD and compared with the results of a previous study and to our own preliminary experimental results. Detailed measurements of the flow field in the VAD model and additional simulations are in progress. Preliminary simulations using both an idealized model of the natural heart as well as a realistic model have identified the limitations of the current numerical methods in dealing with large three-dimensional deformations. Ongoing research aims at extending the range of simulations to include large deformations and to incorporate an anisotropic material model for the heart wall to account for the muscle fibers.

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Section: Blood Flow With Interacting Walls 875mentioning

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Section: Blood Flow With Interacting Walls 871mentioning

confidence: 99%

mentioning

confidence: 99%

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Numerical Simulations of Blood Flow in Artificial and Natural Hearts With Fluid–Structure Interaction

et al. 2008

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“…The same order of mesh points was used to describe flow across MHV in several other works. 22,27,29,38 According to Ge et al 18 meshes with resolution of more than 10 6 grid nodes are required to simulate accurately the complex flow across MHV. Moreover, other studies 15,33,40,42 show that the specific leaflets orientation and design, their opening and closing behavior and the hinge mechanism might have a major effect on their hemodynamic and thrmboembolic characteristics.…”

Section: Discussionmentioning

confidence: 99%

The Hemodynamics of the Berlin Pulsatile VAD and the Role of its MHV Configuration

2006

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The 3D flow in a model of the Berlin ventricular assist device (VAD) chamber with monoleaflet valves placed in S-shape conduits was simulated numerically. The blood flow dynamics were described in terms of flow patterns, velocity, pressure, and shear stress. The hemodynamic properties and the VAD's potential risk for thrombosis were evaluated in terms of mixing and washout properties, and global estimations of platelet level of activation (LOA). In order to evaluate the role of valves on the flow in the chamber, the flow in a model with bileaflet valves in straight conduits was simulated and compared with the original case. The results showed that in both models a large rotating flow was developed in the chamber during filling. This vortex filled the entire chamber and moved constantly up to the peak ejection phase, resulting in relatively low shear stress (up to 0.4 Pa) and no lasting stagnation regions. Significant shear stresses were found near the valves with higher values near the outlet valve in both models. The configuration of valves and conduits had a large effect on VAD washout and mixing properties, with advantage to the bileaflet model. However, since the bileaflet valves exhibited higher shear stresses, higher LOA were found for the bileaflet model.

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Left Ventricular Assist Devices and Gastrointestinal Bleeding: A Narrative Review of Case Reports and Case Series

Islam

Çevik

Madonna

et al. 2013

Clinical Cardiology

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Patients with LVADs have frequent GI bleeds, especially from arteriovenous malformations, which can occur throughout the GI tract. Most diagnostic and therapeutic interventions can be used safely in these patients. The pathogenesis of the GI bleeding in these patients may involve the use of anticoagulant medications, the formation of arteriovenous malformations, loss of von Willebrand factor activity, and mucosal ischemia.

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Investigation of unsteady flow in a model of a ventricular assist device by numerical modelling and comparison with experiment

Cited by 23 publications

References 14 publications

Numerical Simulations of Blood Flow in Artificial and Natural Hearts With Fluid–Structure Interaction

Numerical Simulations of Blood Flow in Artificial and Natural Hearts With Fluid–Structure Interaction

The Hemodynamics of the Berlin Pulsatile VAD and the Role of its MHV Configuration

Left Ventricular Assist Devices and Gastrointestinal Bleeding: A Narrative Review of Case Reports and Case Series

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