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Imtiaz N, Poskus MD, Stoddard WA, Gaborski TR, Day SW. Empirical and Computational Evaluation of Hemolysis in a Microfluidic Extracorporeal Membrane Oxygenator Prototype. MICROMACHINES 2024; 15:790. [PMID: 38930760 PMCID: PMC11205701 DOI: 10.3390/mi15060790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 06/07/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024]
Abstract
Microfluidic devices promise to overcome the limitations of conventional hemodialysis and oxygenation technologies by incorporating novel membranes with ultra-high permeability into portable devices with low blood volume. However, the characteristically small dimensions of these devices contribute to both non-physiologic shear that could damage blood components and laminar flow that inhibits transport. While many studies have been performed to empirically and computationally study hemolysis in medical devices, such as valves and blood pumps, little is known about blood damage in microfluidic devices. In this study, four variants of a representative microfluidic membrane-based oxygenator and two controls (positive and negative) are introduced, and computational models are used to predict hemolysis. The simulations were performed in ANSYS Fluent for nine shear stress-based parameter sets for the power law hemolysis model. We found that three of the nine tested parameters overpredict (5 to 10×) hemolysis compared to empirical experiments. However, three parameter sets demonstrated higher predictive accuracy for hemolysis values in devices characterized by low shear conditions, while another three parameter sets exhibited better performance for devices operating under higher shear conditions. Empirical testing of the devices in a recirculating loop revealed levels of hemolysis significantly lower (<2 ppm) than the hemolysis ranges observed in conventional oxygenators (>10 ppm). Evaluating the model's ability to predict hemolysis across diverse shearing conditions, both through empirical experiments and computational validation, will provide valuable insights for future micro ECMO device development by directly relating geometric and shear stress with hemolysis levels. We propose that, with an informed selection of hemolysis parameters based on the shear ranges of the test device, computational modeling can complement empirical testing in the development of novel high-flow blood-contacting microfluidic devices, allowing for a more efficient iterative design process. Furthermore, the low device-induced hemolysis measured in our study at physiologically relevant flow rates is promising for the future development of microfluidic oxygenators and dialyzers.
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Affiliation(s)
- Nayeem Imtiaz
- Rochester Institute of Technology, Kate Gleason College of Engineering, Rochester, NY 14623, USA; (N.I.); (W.A.S.); (T.R.G.)
| | - Matthew D. Poskus
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA;
| | - William A. Stoddard
- Rochester Institute of Technology, Kate Gleason College of Engineering, Rochester, NY 14623, USA; (N.I.); (W.A.S.); (T.R.G.)
| | - Thomas R. Gaborski
- Rochester Institute of Technology, Kate Gleason College of Engineering, Rochester, NY 14623, USA; (N.I.); (W.A.S.); (T.R.G.)
| | - Steven W. Day
- Rochester Institute of Technology, Kate Gleason College of Engineering, Rochester, NY 14623, USA; (N.I.); (W.A.S.); (T.R.G.)
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Kreinin Y, Talmon Y, Levi M, Khoury M, Or I, Raad M, Bolotin G, Sznitman J, Korin N. A Fibrin-Thrombin Based In Vitro Perfusion System to Study Flow-Related Prosthetic Heart Valves Thrombosis. Ann Biomed Eng 2024; 52:1665-1677. [PMID: 38459196 PMCID: PMC11082030 DOI: 10.1007/s10439-024-03480-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 02/20/2024] [Indexed: 03/10/2024]
Abstract
Prosthetic heart valve (PHV) replacement has increased the survival rate and quality of life for heart valve-diseased patients. However, PHV thrombosis remains a critical problem associated with these procedures. To better understand the PHV flow-related thrombosis problem, appropriate experimental models need to be developed. In this study, we present an in vitro fibrin clot model that mimics clot accumulation in PHVs under relevant hydrodynamic conditions while allowing real-time imaging. We created 3D-printed mechanical aortic valve models that were inserted into a transparent glass aorta model and connected to a system that simulates human aortic flow pulse and pressures. Thrombin was gradually injected into a circulating fibrinogen solution to induce fibrin clot formation, and clot accumulation was quantified via image analysis. The results of valves positioned in a normal versus a tilted configuration showed that clot accumulation correlated with the local flow features and was mainly present in areas of low shear and high residence time, where recirculating flows are dominant, as supported by computational fluid dynamic simulations. Overall, our work suggests that the developed method may provide data on flow-related clot accumulation in PHVs and may contribute to exploring new approaches and valve designs to reduce valve thrombosis.
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Affiliation(s)
- Yevgeniy Kreinin
- Department of Biomedical Engineering, Technion-IIT, 3200003, Haifa, Israel
| | - Yahel Talmon
- Department of Biomedical Engineering, Technion-IIT, 3200003, Haifa, Israel
| | - Moran Levi
- Department of Biomedical Engineering, Technion-IIT, 3200003, Haifa, Israel
| | - Maria Khoury
- Department of Biomedical Engineering, Technion-IIT, 3200003, Haifa, Israel
| | - Itay Or
- Department of Cardiac Surgery, Rambam Health Care Campus, 3109601, Haifa, Israel
| | - Mahli Raad
- Department of Cardiac Surgery, Rambam Health Care Campus, 3109601, Haifa, Israel
| | - Gil Bolotin
- Department of Cardiac Surgery, Rambam Health Care Campus, 3109601, Haifa, Israel
- The Ruth Bruce Rappaport Faculty of Medicine, Technion-IIT, 3525433, Haifa, Israel
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion-IIT, 3200003, Haifa, Israel
| | - Netanel Korin
- Department of Biomedical Engineering, Technion-IIT, 3200003, Haifa, Israel.
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Hanekop G, Kollmeier JM, Frahm J, Iwanowski I, Khabbazzadeh S, Kutschka I, Tirilomis T, Ulrich C, Friedrich MG. Turbulence in surgical suction heads as detected by MRI. THE JOURNAL OF EXTRA-CORPOREAL TECHNOLOGY 2023; 55:70-81. [PMID: 37378439 DOI: 10.1051/ject/2023015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 04/06/2023] [Indexed: 06/29/2023]
Abstract
BACKGROUND Blood loss is common during surgical procedures, especially in open cardiac surgery. Allogenic blood transfusion is associated with increased morbidity and mortality. Blood conservation programs in cardiac surgery recommend re-transfusion of shed blood directly or after processing, as this decreases transfusion rates of allogenic blood. But aspiration of blood from the wound area is often associated with increased hemolysis, due to flow induced forces, mainly through development of turbulence. METHODS We evaluated magnetic resonance imaging (MRI) as a qualitative tool for detection of turbulence. MRI is sensitive to flow; this study uses velocity-compensated T1-weighted 3D MRI for turbulence detection in four geometrically different cardiotomy suction heads under comparable flow conditions (0-1250 mL/min). RESULTS Our standard control suction head Model A showed pronounced signs of turbulence at all flow rates measured, while turbulence was only detectable in our modified Models 1-3 at higher flow rates (Models 1 and 3) or not at all (Model 2). CONCLUSIONS The comparison of flow performance of surgical suction heads with different geometries via acceleration-sensitized 3D MRI revealed significant differences in turbulence development between our standard control Model A and the modified alternatives (Models 1-3). As flow conditions during measurement have been comparable, the specific geometry of the respective suction heads must have been the main factor responsible. The underlying mechanisms and causative factors can only be speculated about, but as other investigations have shown, hemolytic activity is positively associated with degree of turbulence. The turbulence data measured in this study correlate with data from other investigations about hemolysis induced by surgical suction heads. The experimental MRI technique used showed added value for further elucidating the underlying physical phenomena causing blood damage due to non-physiological flow.
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Affiliation(s)
- Gunnar Hanekop
- Department of Anesthesiology, Intensive Care, Emergency Medicine, Pain Therapy, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
| | - Jost M Kollmeier
- Max-Planck-Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Goettingen, Germany
| | - Jens Frahm
- Max-Planck-Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Goettingen, Germany
| | - Ireneusz Iwanowski
- Department of Heart-Thoracic- and Vascular-Surgery, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
| | - Sepideh Khabbazzadeh
- Department of Anesthesiology, Intensive Care, Emergency Medicine, Pain Therapy, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
| | - Ingo Kutschka
- Department of Heart-Thoracic- and Vascular-Surgery, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
| | - Theodor Tirilomis
- Department of Heart-Thoracic- and Vascular-Surgery, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
| | - Christian Ulrich
- Department of Heart-Thoracic- and Vascular-Surgery, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
| | - Martin G Friedrich
- Department of Heart-Thoracic- and Vascular-Surgery, University Medicine, Georg-August-University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
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Torner B, Frank D, Grundmann S, Wurm FH. Flow simulation-based particle swarm optimization for developing improved hemolysis models. Biomech Model Mechanobiol 2022; 22:401-416. [PMID: 36441414 PMCID: PMC10097800 DOI: 10.1007/s10237-022-01653-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/23/2022] [Indexed: 11/29/2022]
Abstract
AbstractThe improvement and development of blood-contacting devices, such as mechanical circulatory support systems, is a life saving endeavor. These devices must be designed in such a way that they ensure the highest hemocompatibility. Therefore, in-silico trials (flow simulations) offer a quick and cost-effective way to analyze and optimize the hemocompatibility and performance of medical devices. In that regard, the prediction of blood trauma, such as hemolysis, is the key element to ensure the hemocompatibility of a device. But, despite decades of research related to numerical hemolysis models, their accuracy and reliability leaves much to be desired. This study proposes a novel optimization path, which is capable of improving existing models and aid in the development of future hemolysis models. First, flow simulations of three, turbulent blood flow test cases (capillary tube, FDA nozzle, FDA pump) were performed and hemolysis was numerically predicted by the widely-applied stress-based hemolysis models. Afterward, a multiple-objective particles swarm optimization (MOPSO) was performed to tie the physiological stresses of the simulated flow field to the measured hemolysis using an equivalent of over one million numerically determined hemolysis predictions. The results show that our optimization is capable of improving upon existing hemolysis models. However, it also unveils some deficiencies and limits of hemolysis prediction with stress-based models, which will need to be addressed in order to improve its reliability.
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Escher A, Hubmann EJ, Karner B, Messner B, Laufer G, Kertzscher U, Zimpfer D, Granegger M. Linking Hydraulic Properties to Hemolytic Performance of Rotodynamic Blood Pumps. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Andreas Escher
- Department of Cardiac Surgery Medical University of Vienna Vienna 1090 Austria
| | | | - Barbara Karner
- Department of Cardiac Surgery Medical University of Vienna Vienna 1090 Austria
| | - Barbara Messner
- Cardiac Surgery Research Laboratory Medical University of Vienna Vienna 1090 Austria
| | - Günther Laufer
- Department of Cardiac Surgery Medical University of Vienna Vienna 1090 Austria
| | - Ulrich Kertzscher
- Biofluid Mechanics Laboratory Charité‐Universitätsmedizin Berlin 10117 Berlin Germany
| | - Daniel Zimpfer
- Department of Cardiac Surgery Medical University of Vienna Vienna 1090 Austria
| | - Marcus Granegger
- Department of Cardiac Surgery Medical University of Vienna Vienna 1090 Austria
- Biofluid Mechanics Laboratory Charité‐Universitätsmedizin Berlin 10117 Berlin Germany
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Krisher JA, Malinauskas RA, Day SW. The Effect of Blood Viscosity on Shear-Induced Hemolysis using a Magnetically Levitated Shearing Device. Artif Organs 2022; 46:1027-1039. [PMID: 35030287 DOI: 10.1111/aor.14172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 11/17/2021] [Accepted: 12/30/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Blood contacting medical devices, including rotary blood pumps, can cause shear-induced blood damage that may lead to adverse effects in patients. Due in part to an inadequate understanding of how cell-scale fluid mechanics impact red blood cell membrane deformation and damage, there is currently not a uniformly accepted engineering model for predicting blood damage caused by complex flow fields within ventricular assist devices (VADs). METHODS We empirically investigated hemolysis in a magnetically levitated axial Couette flow device typical of a rotary VAD. The device is able to accurately control the shear rate and exposure time experienced by blood and to minimize the effects of other uncharacterized stresses. Using this device, we explored the effects of both hematocrit and plasma viscosity on shear-induced hemolysis to characterize blood damage based on the viscosity-independent shear rate, rather than on shear stress. RESULTS Over a shear rate range of 20,000-80,000 1/s, the Index of Hemolysis (IH) was found to be dependent upon and well-predicted by shear rate alone. IH was independent of hematocrit, bulk viscosity, or the suspension media viscosity, and less correlated to shear stress (MSE=0.46-0.75) than to shear rate (MSE=0.06-0.09). CONCLUSION This study recommends that future investigations of shear-induced blood damage report findings with respect to the viscosity-neutral term of shear rate, in addition to the bulk whole blood viscosity measured at an appropriate shear rate relevant to the flow conditions of the device.
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Affiliation(s)
- James A Krisher
- Kate Gleason College of Engineering, Rochester Institute of Technology
| | | | - Steven W Day
- Kate Gleason College of Engineering, Rochester Institute of Technology
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Konnigk L, Torner B, Bruschewski M, Grundmann S, Wurm FH. Equivalent Scalar Stress Formulation Taking into Account Non-Resolved Turbulent Scales. Cardiovasc Eng Technol 2021; 12:251-272. [PMID: 33675019 PMCID: PMC8169507 DOI: 10.1007/s13239-021-00526-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 02/09/2021] [Indexed: 01/01/2023]
Abstract
PURPOSE Cardiovascular engineering includes flows with fluid-dynamical stresses as a parameter of interest. Mechanical stresses are high-risk factors for blood damage and can be assessed by computational fluid dynamics. By now, it is not described how to calculate an adequate scalar stress out of turbulent flow regimes when the whole share of turbulence is not resolved by the simulation method and how this impacts the stress calculation. METHODS We conducted direct numerical simulations (DNS) of test cases (a turbulent channel flow and the FDA nozzle) in order to access all scales of flow movement. After validation of both DNS with literature und experimental data using magnetic resonance imaging, the mechanical stress is calculated as a baseline. Afterwards, same flows are calculated using state-of-the-art turbulence models. The stresses are computed for every result using our definition of an equivalent scalar stress, which includes the influence from respective turbulence model, by using the parameter dissipation. Afterwards, the results are compared with the baseline data. RESULTS The results show a good agreement regarding the computed stress. Even when no turbulence is resolved by the simulation method, the results agree well with DNS data. When the influence of non-resolved motion is neglected in the stress calculation, it is underpredicted in all cases. CONCLUSION With the used scalar stress formulation, it is possible to include information about the turbulence of the flow into the mechanical stress calculation even when the used simulation method does not resolve any turbulence.
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Affiliation(s)
- Lucas Konnigk
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Germany.
| | - Benjamin Torner
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Germany
| | - Martin Bruschewski
- Institute of Fluid Mechanics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Germany
| | - Sven Grundmann
- Institute of Fluid Mechanics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Germany
| | - Frank-Hendrik Wurm
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Germany
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Torner B, Konnigk L, Abroug N, Wurm H. Turbulence and turbulent flow structures in a ventricular assist device-A numerical study using the large-eddy simulation. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3431. [PMID: 33336869 DOI: 10.1002/cnm.3431] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 12/14/2020] [Accepted: 12/14/2020] [Indexed: 06/12/2023]
Abstract
Numerical flow simulations that analyze the turbulent flow characteristics within a turbopump are important for optimizing the efficiency of such machines. In the case of ventricular assist devices (VADs), turbulent flow characteristics must be also examined in order to improve hemocompatibility. Turbulence increases the shear stresses in the VAD flow, which can lead to an increased damage to the transported blood components. Therefore, an understanding of the turbulent flow patterns and their significance for the numerical blood damage prediction is particularly important for flow optimizations in VADs in order to identify and thus minimize flow regions where blood could be damaged due to high turbulent stresses. Nevertheless, the turbulence occurring in VADs and the local turbulent structures that lead to increased turbulent stresses have not yet been analyzed in detail in these machines. Therefore, this study aims to investigate the turbulence in an axial VAD in a comprehensive and double tracked way. First, the flow in an axial VAD was computed using the large-eddy simulation method, and it was verified that the majority of the turbulence was directly resolved by the simulation. Then, the turbulent flow state of the VAD was quantified globally. For this purpose, a self-designed evaluation method, the power loss analysis, was used. Subsequently, local flow regions and flow structures were identified where significant turbulent stresses prevail. It will be shown that the identified regions are universal and will also occur in other axial blood pumps as well, for example, in the HeartMate II.
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Affiliation(s)
- Benjamin Torner
- Faculty of Mechanical Engineering and Marine Technology, Institute of Turbomachinery, University of Rostock, Rostock, Germany
| | - Lucas Konnigk
- Faculty of Mechanical Engineering and Marine Technology, Institute of Turbomachinery, University of Rostock, Rostock, Germany
| | - Nada Abroug
- Faculty of Mechanical Engineering and Marine Technology, Institute of Turbomachinery, University of Rostock, Rostock, Germany
| | - Hendrik Wurm
- Faculty of Mechanical Engineering and Marine Technology, Institute of Turbomachinery, University of Rostock, Rostock, Germany
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Torner B, Konnigk L, Wurm FH. Influence of turbulent shear stresses on the numerical blood damage prediction in a ventricular assist device. Int J Artif Organs 2019; 42:735-747. [PMID: 31328604 DOI: 10.1177/0391398819861395] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The blood damage prediction in rotary blood pumps is an important procedure to evaluate the hemocompatibility of such systems. Blood damage is caused by shear stresses to the blood cells and their exposure times. The total impact of an equivalent shear stress can only be taken into account when turbulent stresses are included in the blood damage prediction. The aim of this article was to analyze the influence of the turbulent stresses on the damage prediction in a rotary blood pump's flow. Therefore, the flow in a research blood pump was computed using large eddy simulations. A highly turbulence-resolving setup was used in order to directly resolve most of the computed stresses. The simulations were performed at the design point and an operation point with lower flow rate. Blood damage was predicted using three damage models (volumetric analysis of exceeded stress thresholds, hemolysis transport equation, and hemolysis approximation via volume integral) and two shear stress definitions (with and without turbulent stresses). For both simulations, turbulent stresses are the dominant stresses away from the walls. Here, they act in a range between 9 and 50 Pa. Nonetheless, the mean stresses in the proximity of the walls reach levels, which are one order of magnitude higher. Due to this, the turbulent stresses have a small impact on the results of the hemolysis prediction. Yet, turbulent stresses should be included in the damage prediction, since they belong to the total equivalent stress definition and could impact the damage on proteins or platelets.
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Affiliation(s)
- Benjamin Torner
- Institute of Turbomachinery, University of Rostock, Rostock, Germany
| | - Lucas Konnigk
- Institute of Turbomachinery, University of Rostock, Rostock, Germany
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Simmonds M, Thamsen B, Kertzscher U. Blood damage in ventricular assist devices. Int J Artif Organs 2019; 42:111-112. [PMID: 30862276 DOI: 10.1177/0391398819834736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Michael Simmonds
- 1 Biorheology Research Laboratory, Menzies Health Institute Queensland, Australia
| | - Bente Thamsen
- 2 Pediatric Heart Center, University Children's Hospital Zurich, Switzerland
| | - Ulrich Kertzscher
- 3 Biofluid Mechanics Laboratory, Charité - Universitaetsmedizin Berlin, Germany
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