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Yao T, Pajaziti E, Quail M, Schievano S, Steeden J, Muthurangu V. Image2Flow: A proof-of-concept hybrid image and graph convolutional neural network for rapid patient-specific pulmonary artery segmentation and CFD flow field calculation from 3D cardiac MRI data. PLoS Comput Biol 2024; 20:e1012231. [PMID: 38900817 PMCID: PMC11218942 DOI: 10.1371/journal.pcbi.1012231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 07/02/2024] [Accepted: 06/06/2024] [Indexed: 06/22/2024] Open
Abstract
Computational fluid dynamics (CFD) can be used for non-invasive evaluation of hemodynamics. However, its routine use is limited by labor-intensive manual segmentation, CFD mesh creation, and time-consuming simulation. This study aims to train a deep learning model to both generate patient-specific volume-meshes of the pulmonary artery from 3D cardiac MRI data and directly estimate CFD flow fields. This proof-of-concept study used 135 3D cardiac MRIs from both a public and private dataset. The pulmonary arteries in the MRIs were manually segmented and converted into volume-meshes. CFD simulations were performed on ground truth meshes and interpolated onto point-point correspondent meshes to create the ground truth dataset. The dataset was split 110/10/15 for training, validation, and testing. Image2Flow, a hybrid image and graph convolutional neural network, was trained to transform a pulmonary artery template to patient-specific anatomy and CFD values, taking a specific inlet velocity as an additional input. Image2Flow was evaluated in terms of segmentation, and the accuracy of predicted CFD was assessed using node-wise comparisons. In addition, the ability of Image2Flow to respond to increasing inlet velocities was also evaluated. Image2Flow achieved excellent segmentation accuracy with a median Dice score of 0.91 (IQR: 0.86-0.92). The median node-wise normalized absolute error for pressure and velocity magnitude was 11.75% (IQR: 9.60-15.30%) and 9.90% (IQR: 8.47-11.90), respectively. Image2Flow also showed an expected response to increased inlet velocities with increasing pressure and velocity values. This proof-of-concept study has shown that it is possible to simultaneously perform patient-specific volume-mesh based segmentation and pressure and flow field estimation using Image2Flow. Image2Flow completes segmentation and CFD in ~330ms, which is ~5000 times faster than manual methods, making it more feasible in a clinical environment.
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Affiliation(s)
- Tina Yao
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Endrit Pajaziti
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Michael Quail
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Silvia Schievano
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Jennifer Steeden
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Vivek Muthurangu
- Institute of Cardiovascular Science, University College London, London, United Kingdom
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2
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Degenhardt K, Schmidt S, Aigner CS, Kratzer FJ, Seiter DP, Mueller M, Kolbitsch C, Nagel AM, Wieben O, Schaeffter T, Schulz-Menger J, Schmitter S. Toward accurate and fast velocity quantification with 3D ultrashort TE phase-contrast imaging. Magn Reson Med 2024; 91:1994-2009. [PMID: 38174601 DOI: 10.1002/mrm.29978] [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: 08/11/2023] [Revised: 11/28/2023] [Accepted: 11/28/2023] [Indexed: 01/05/2024]
Abstract
PURPOSE Traditional phase-contrast MRI is affected by displacement artifacts caused by non-synchronized spatial- and velocity-encoding time points. The resulting inaccurate velocity maps can affect the accuracy of derived hemodynamic parameters. This study proposes and characterizes a 3D radial phase-contrast UTE (PC-UTE) sequence to reduce displacement artifacts. Furthermore, it investigates the displacement of a standard Cartesian flow sequence by utilizing a displacement-free synchronized-single-point-imaging MR sequence (SYNC-SPI) that requires clinically prohibitively long acquisition times. METHODS 3D flow data was acquired at 3T at three different constant flow rates and varying spatial resolutions in a stenotic aorta phantom using the proposed PC-UTE, a Cartesian flow sequence, and a SYNC-SPI sequence as reference. Expected displacement artifacts were calculated from gradient timing waveforms and compared to displacement values measured in the in vitro flow experiments. RESULTS The PC-UTE sequence reduces displacement and intravoxel dephasing, leading to decreased geometric distortions and signal cancellations in magnitude images, and more spatially accurate velocity quantification compared to the Cartesian flow acquisitions; errors increase with velocity and higher spatial resolution. CONCLUSION PC-UTE MRI can measure velocity vector fields with greater accuracy than Cartesian acquisitions (although pulsatile fields were not studied) and shorter scan times than SYNC-SPI. As such, this approach is superior to traditional Cartesian 3D and 4D flow MRI when spatial misrepresentations cannot be tolerated, for example, when computational fluid dynamics simulations are compared to or combined with in vitro or in vivo measurements, or regional parameters such as wall shear stress are of interest.
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Affiliation(s)
- Katja Degenhardt
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Simon Schmidt
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christoph S Aigner
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
| | - Fabian J Kratzer
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Daniel P Seiter
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
| | - Max Mueller
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Kolbitsch
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
| | - Armin M Nagel
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
- Department of Radiology, University of Wisconsin Madison, Madison, Wisconsin, USA
| | - Tobias Schaeffter
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
- School of Imaging Science and Biomedical Engineering, King's College London, London, United Kingdom
- Department of Medical Engineering, Technical University of Berlin, Berlin, Germany
| | - Jeanette Schulz-Menger
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Working Group on Cardiovascular Magnetic Resonance, Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- Department of Cardiology and Nephrology, HELIOS Hospital Berlin-Buch, Berlin, Germany
| | - Sebastian Schmitter
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
- Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Ali AM, Ghobashy AA, Sultan AA, Elkhodary KI, El-Morsi M. A 3D scaling law for supravalvular aortic stenosis suited for stethoscopic auscultations. Heliyon 2024; 10:e26190. [PMID: 38390109 PMCID: PMC10881376 DOI: 10.1016/j.heliyon.2024.e26190] [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: 05/10/2023] [Revised: 11/24/2023] [Accepted: 02/08/2024] [Indexed: 02/24/2024] Open
Abstract
In this study a frequency scaling law for 3D anatomically representative supravalvular aortic stenosis (SVAS) cases is proposed. The law is uncovered for stethoscopy's preferred auscultation range (70-120 Hz). LES simulations are performed on the CFD solver Fluent, leveraging Simulia's Living Heart Human Model (LHHM), modified to feature hourglass stenoses that range between 30 to 80 percent (mild to severe) in addition to the descending aorta. For physiological hemodynamic boundary conditions the Windkessel model is implemented via a UDF subroutine. The flow-generated acoustic signal is then extracted using the FW-H model and analyzed using FFT. A preferred receiver location that matches clinical practice is confirmed (right intercostal space) and a correlation between the degree of stenosis and a corresponding acoustic frequency is obtained. Five clinical auscultation signals are tested against the scaling law, with the findings interpreted in relation to the NHS classification of stenosis and to the assessments of experienced cardiologists. The scaling law is thus shown to succeed as a potential quantitative decision-support tool for clinicians, enabling them to reliably interpret stethoscopic auscultations for all degrees of stenosis, which is especially useful for moderate degrees of SVAS. Computational investigation of more complex stenotic cases would enhance the clinical relevance of this proposed scaling law, and will be explored in future research.
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Affiliation(s)
- Ahmed M Ali
- Department of Mechanical Engineering, The American University in Cairo, 11835 New Cairo, Egypt
| | - Aly A Ghobashy
- Department of Mechanical Engineering, The American University in Cairo, 11835 New Cairo, Egypt
| | - Abdelrahman A Sultan
- Department of Mechanical Engineering, The American University in Cairo, 11835 New Cairo, Egypt
| | - Khalil I Elkhodary
- Department of Mechanical Engineering, The American University in Cairo, 11835 New Cairo, Egypt
| | - Mohamed El-Morsi
- Department of Mechanical Engineering, The American University in Cairo, 11835 New Cairo, Egypt
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Feiger B, Jensen CW, Bryner BS, Segars WP, Randles A. Modeling the effect of patient size on cerebral perfusion during veno-arterial extracorporeal membrane oxygenation. Perfusion 2023:2676591231187962. [PMID: 37395266 PMCID: PMC10786318 DOI: 10.1177/02676591231187962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
INTRODUCTION A well-known complication of veno-arterial extracorporeal membrane oxygenation (VA ECMO) is differential hypoxia, in which poorly-oxygenated blood ejected from the left ventricle mixes with and displaces well-oxygenated blood from the circuit, thereby causing cerebral hypoxia and ischemia. We sought to characterize the impact of patient size and anatomy on cerebral perfusion under a range of different VA ECMO flow conditions. METHODS We use one-dimensional (1D) flow simulations to investigate mixing zone location and cerebral perfusion across 10 different levels of VA ECMO support in eight semi-idealized patient geometries, for a total of 80 scenarios. Measured outcomes included mixing zone location and cerebral blood flow (CBF). RESULTS Depending on patient anatomy, we found that a VA ECMO support ranging between 67-97% of a patient's ideal cardiac output was needed to perfuse the brain. In some cases, VA ECMO flows exceeding 90% of the patient's ideal cardiac output are needed for adequate cerebral perfusion. CONCLUSIONS Individual patient anatomy markedly affects mixing zone location and cerebral perfusion in VA ECMO. Future fluid simulations of VA ECMO physiology should incorporate varied patient sizes and geometries in order to best provide insights toward reducing neurologic injury and improved outcomes in this patient population.
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Affiliation(s)
- Bradley Feiger
- Department of Bioengineering, School of Medicine, Duke University, Durham, NC, USA
| | - Christopher W Jensen
- Department of Bioengineering, School of Medicine, Duke University, Durham, NC, USA
- Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University, Durham, NC, USA
| | - Benjamin S Bryner
- Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University, Durham, NC, USA
| | - William P Segars
- Department of Radiology, School of Medicine, Duke Medicine, Chicago, IL, USA
| | - Amanda Randles
- Department of Bioengineering, School of Medicine, Duke University, Durham, NC, USA
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Cha MJ, An DG, Kang M, Kim HM, Kim SW, Cho I, Hong J, Choi H, Cho JH, Shin SY, Song S. Correct Closure of the Left Atrial Appendage Reduces Stagnant Blood Flow and the Risk of Thrombus Formation: A Proof-of-Concept Experimental Study Using 4D Flow Magnetic Resonance Imaging. Korean J Radiol 2023; 24:647-659. [PMID: 37404107 DOI: 10.3348/kjr.2023.0173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 04/06/2023] [Accepted: 04/17/2023] [Indexed: 07/06/2023] Open
Abstract
OBJECTIVE The study was conducted to investigate the effect of correct occlusion of the left atrial appendage (LAA) on intracardiac blood flow and thrombus formation in patients with atrial fibrillation (AF) using four-dimensional (4D) flow magnetic resonance imaging (MRI) and three-dimensional (3D)-printed phantoms. MATERIALS AND METHODS Three life-sized 3D-printed left atrium (LA) phantoms, including a pre-occlusion (i.e., before the occlusion procedure) model and correctly and incorrectly occluded post-procedural models, were constructed based on cardiac computed tomography images from an 86-year-old male with long-standing persistent AF. A custom-made closed-loop flow circuit was set up, and pulsatile simulated pulmonary venous flow was delivered by a pump. 4D flow MRI was performed using a 3T scanner, and the images were analyzed using MATLAB-based software (R2020b; Mathworks). Flow metrics associated with blood stasis and thrombogenicity, such as the volume of stasis defined by the velocity threshold (|V̅| < 3 cm/s), surface-and-time-averaged wall shear stress (WSS), and endothelial cell activation potential (ECAP), were analyzed and compared among the three LA phantom models. RESULTS Different spatial distributions, orientations, and magnitudes of LA flow were directly visualized within the three LA phantoms using 4D flow MRI. The time-averaged volume and its ratio to the corresponding entire volume of LA flow stasis were consistently reduced in the correctly occluded model (70.82 mL and 39.0%, respectively), followed by the incorrectly occluded (73.17 mL and 39.0%, respectively) and pre-occlusion (79.11 mL and 39.7%, respectively) models. The surface-and-time-averaged WSS and ECAP were also lowest in the correctly occluded model (0.048 Pa and 4.004 Pa-1 , respectively), followed by the incorrectly occluded (0.059 Pa and 4.792 Pa-1 , respectively) and pre-occlusion (0.072 Pa and 5.861 Pa-1 , respectively) models. CONCLUSION These findings suggest that a correctly occluded LAA leads to the greatest reduction in LA flow stasis and thrombogenicity, presenting a tentative procedural goal to maximize clinical benefits in patients with AF.
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Affiliation(s)
- Min Jae Cha
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Don-Gwan An
- Department of Mechanical Convergence Engineering, Hanyang University, Seoul, Korea
- Center for Precision Medicine Platform Based-on Smart Hemo-Dynamic Index, Seoul, Korea
| | - Minsoo Kang
- Department of Mechanical Convergence Engineering, Hanyang University, Seoul, Korea
- Center for Precision Medicine Platform Based-on Smart Hemo-Dynamic Index, Seoul, Korea
| | - Hyue Mee Kim
- Division of Cardiology, Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Sang-Wook Kim
- Division of Cardiology, Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Iksung Cho
- Division of Cardiology, Department of Internal Medicine, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Korea
| | - Joonhwa Hong
- Department of Thoracic and Cardiovascular Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Hyewon Choi
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Jee-Hyun Cho
- Bio-Chemical Analysis Team, Korea Basic Science Institute, Cheongju, Korea
| | - Seung Yong Shin
- Center for Precision Medicine Platform Based-on Smart Hemo-Dynamic Index, Seoul, Korea
- Division of Cardiology, Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
| | - Simon Song
- Department of Mechanical Convergence Engineering, Hanyang University, Seoul, Korea
- Center for Precision Medicine Platform Based-on Smart Hemo-Dynamic Index, Seoul, Korea
- Institute of Nano Science and Technology, Hanyang University, Seoul, Korea.
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Validation of the Reduced Unified Continuum Formulation Against In Vitro 4D-Flow MRI. Ann Biomed Eng 2023; 51:377-393. [PMID: 35963921 DOI: 10.1007/s10439-022-03038-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 07/25/2022] [Indexed: 01/25/2023]
Abstract
We previously introduced and verified the reduced unified continuum formulation for vascular fluid-structure interaction (FSI) against Womersley's deformable wall theory. Our present work seeks to investigate its performance in a patient-specific aortic setting in which assumptions of idealized geometries and velocity profiles are invalid. Specifically, we leveraged 2D magnetic resonance imaging (MRI) and 4D-flow MRI to extract high-resolution anatomical and hemodynamic information from an in vitro flow circuit embedding a compliant 3D-printed aortic phantom. To accurately reflect experimental conditions, we numerically implemented viscoelastic external tissue support, vascular tissue prestressing, and skew boundary conditions enabling in-plane vascular motion at each inlet and outlet. Validation of our formulation is achieved through close quantitative agreement in pressures, lumen area changes, pulse wave velocity, and early systolic velocities, as well as qualitative agreement in late systolic flow structures. Our validated suite of FSI techniques offers a computationally efficient approach for numerical simulation of vascular hemodynamics. This study is among the first to validate a cardiovascular FSI formulation against an in vitro flow circuit involving a compliant vascular phantom of complex patient-specific anatomy.
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Capelli C, Bertolini M, Schievano S. 3D-printed and computational models: a combined approach for patient-specific studies. 3D Print Med 2023. [DOI: 10.1016/b978-0-323-89831-7.00011-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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8
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Cherry M, Khatir Z, Khan A, Bissell M. The impact of 4D-Flow MRI spatial resolution on patient-specific CFD simulations of the thoracic aorta. Sci Rep 2022; 12:15128. [PMID: 36068322 PMCID: PMC9448751 DOI: 10.1038/s41598-022-19347-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/29/2022] [Indexed: 11/29/2022] Open
Abstract
Magnetic Resonance Imaging (MRI) is considered the gold standard of medical imaging technologies as it allows for accurate imaging of blood vessels. 4-Dimensional Flow Magnetic Resonance Imaging (4D-Flow MRI) is built on conventional MRI, and provides flow data in the three vector directions and a time resolved magnitude data set. As such it can be used to retrospectively calculate haemodynamic parameters of interest, such as Wall Shear Stress (WSS). However, multiple studies have indicated that a significant limitation of the imaging technique is the spatiotemporal resolution that is currently available. Recent advances have proposed and successfully integrated 4D-Flow MRI imaging techniques with Computational Fluid Dynamics (CFD) to produce patient-specific simulations that have the potential to aid in treatments,surgical decision making, and risk stratification. However, the consequences of using insufficient 4D-Flow MRI spatial resolutions on any patient-specific CFD simulations is currently unclear, despite being a recognised limitation. The research presented in this study aims to quantify the inaccuracies in patient-specific 4D-Flow MRI based CFD simulations that can be attributed to insufficient spatial resolutions when acquiring 4D-Flow MRI data. For this research, a patient has undergone four 4D-Flow MRI scans acquired at various isotropic spatial resolutions and patient-specific CFD simulations have subsequently been run using geometry and velocity data produced from each scan. It was found that compared to CFD simulations based on a \documentclass[12pt]{minimal}
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\begin{document}$$1.5\,{\text {mm}} \times 1.5\,{\text {mm}} \times 1.5\,{\text {mm}}$$\end{document}1.5mm×1.5mm×1.5mm, using a spatial resolution of \documentclass[12pt]{minimal}
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\begin{document}$$4\,{\text {mm}} \times 4\,{\text {mm}} \times 4\,{\text {mm}}$$\end{document}4mm×4mm×4mm substantially underestimated the maximum velocity magnitude at peak systole by \documentclass[12pt]{minimal}
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\begin{document}$$110.55\%$$\end{document}110.55%. The impacts of 4D-Flow MRI spatial resolution on WSS calculated from CFD simulations have been investigated and it has been shown that WSS is underestimated in CFD simulations that are based on a coarse 4D-Flow MRI spatial resolution. The authors have concluded that a minimum 4D-Flow MRI spatial resolution of \documentclass[12pt]{minimal}
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\begin{document}$$1.5\,{\text {mm}} \times 1.5\,{\text {mm}} \times 1.5\,{\text {mm}}$$\end{document}1.5mm×1.5mm×1.5mm must be used when acquiring 4D-Flow MRI data to perform patient-specific CFD simulations. A coarser spatial resolution will produce substantial differences within the flow field and geometry.
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Affiliation(s)
- Molly Cherry
- CDT in Fluid Dynamics, School of Computing, University of Leeds, Leeds, LS2 9JT, UK.
| | - Zinedine Khatir
- School of Engineering and the Built Environment, Birmingham City University, Birmingham, B4 7XG, UK.,School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Amirul Khan
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
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Contento J, Mass P, Cleveland V, Aslan S, Matsushita H, Hayashi H, Nguyen V, Kawaji K, Loke YH, Nelson K, Johnson J, Krieger A, Olivieri L, Hibino N. Location matters: Offset in tissue-engineered vascular graft implantation location affects wall shear stress in porcine models. JTCVS OPEN 2022; 12:355-363. [PMID: 36590712 PMCID: PMC9801286 DOI: 10.1016/j.xjon.2022.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/28/2022] [Accepted: 08/08/2022] [Indexed: 01/04/2023]
Abstract
Objective Although surgical simulation using computational fluid dynamics has advanced, little is known about the accuracy of cardiac surgical procedures after patient-specific design. We evaluated the effects of discrepancies in location for patient-specific simulation and actual implantation on hemodynamic performance of patient-specific tissue-engineered vascular grafts (TEVGs) in porcine models. Methods Magnetic resonance angiography and 4-dimensional (4D) flow data were acquired in porcine models (n = 11) to create individualized TEVGs. Graft shapes were optimized and manufactured by electrospinning bioresorbable material onto a metal mandrel. TEVGs were implanted 1 or 3 months postimaging, and postoperative magnetic resonance angiography and 4D flow data were obtained and segmented. Displacement between intended and observed TEVG position was determined through center of mass analysis. Hemodynamic data were obtained from 4D flow analysis. Displacement and hemodynamic data were compared using linear regression. Results Patient-specific TEVGs were displaced between 1 and 8 mm during implantation compared with their surgically simulated, intended locations. Greater offset between intended and observed position correlated with greater wall shear stress (WSS) in postoperative vasculature (P < .01). Grafts that were implanted closer to their intended locations showed decreased WSS. Conclusions Patient-specific TEVGs are designed for precise locations to help optimize hemodynamic performance. However, if TEVGs were implanted far from their intended location, worse WSS was observed. This underscores the importance of not only patient-specific design but also precision-guided implantation to optimize hemodynamics in cardiac surgery and increase reproducibility of surgical simulation.
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Key Words
- 4D, four-dimensional
- AR, augmented reality
- CFD, computational fluid dynamics
- CHD, congenital heart disease
- LPA, left pulmonary artery
- MPA, main pulmonary artery
- MRA, magnetic resonance angiography
- MRI, magnetic resonance imaging
- PA, pulmonary artery
- RPA, right pulmonary artery
- SCA, subclavian artery
- STL, stereolithography
- TEVG, tissue-engineered vascular graft
- WSS, wall shear stress
- center of gravity
- computational fluid dynamics
- displacement
- hemodynamics
- surgical planning
- tissue-engineered vascular grafts
- wall shear stress
- αSMA, α-smooth muscle actin
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Affiliation(s)
| | - Paige Mass
- Department of Cardiology, Children's National Hospital, Washington, DC
| | - Vincent Cleveland
- Department of Cardiology, Children's National Hospital, Washington, DC
| | - Seda Aslan
- Laboratory for Computational Sensing and Robotics, Johns Hopkins University, Baltimore, Md
| | - Hiroshi Matsushita
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Hidenori Hayashi
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill
| | - Vivian Nguyen
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, Ill
| | - Keigo Kawaji
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, Ill
| | - Yue-Hin Loke
- Department of Cardiology, Children's National Hospital, Washington, DC
| | | | | | - Axel Krieger
- Laboratory for Computational Sensing and Robotics, Johns Hopkins University, Baltimore, Md
| | - Laura Olivieri
- Department of Cardiology, Children's National Hospital, Washington, DC
| | - Narutoshi Hibino
- Division of Cardiac Surgery, Department of Surgery, University of Chicago, Chicago, Ill,Department of Cardiovascular Surgery, Advocate Children's Hospital, Oak Lawn, Ill,Address for reprints: Narutoshi Hibino, MD, PhD, Section of Cardiac Surgery, Department of Surgery, The University of Chicago, Advocate Children's Hospital, 5841 S Maryland Ave, Room E500B, MC5040, Chicago, IL 60637.
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10
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Conijn M, Wintermans L, Metselaar R, Ruisch J, Bax E, van Egmond C, Nieuwenstein B, Warmerdam E, Krings G. A 3D printed pulmonary mock loop for hemodynamic studies in congenital heart disease. Biomed Phys Eng Express 2022; 8. [PMID: 35970091 DOI: 10.1088/2057-1976/ac8993] [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: 02/14/2022] [Accepted: 08/15/2022] [Indexed: 11/11/2022]
Abstract
Background With the increasing survival of the congenital heart disease population, there is a growing need for in-depth understanding of blood circulation in these patients. Mock loops provide the opportunity for comprehensive hemodynamic studies without burden and risks for patients. This study aimed to evaluate the ability of the presented mock loop to mimic the hemodynamics of the pulmonary circulation with and without stenosis and the MR compatibility of the system. Methods A pulsatile pump with two chambers, separated by a flexible membrane, was designed and 3D printed. A cough assist device applied an alternating positive and negative pressure on the membrane. One adult, and three pediatric pulmonary bifurcations were 3D printed and incorporated in the setup. Two pediatric models had a 50% stenosis of the left branch. Bilateral compliance chambers allowed for individual compliance tuning. A reservoir determined the diastolic pressure. Two carbon heart valves guaranteed unidirectional flow. The positive pressure on the cough assist device was tuned until an adequate stroke volume was reached with a frequency of 60 bpm. Flow and pressure measurements were performed on the main pulmonary artery and the two branches. The MR compatibility of the setup was evaluated. Results A stroke volume with a cardiac index of 2L/min/m2 was achieved in all models. Physiological pressure curves were generated in both normal and stenotic models. The mock loop was MR compatible. Conclusion This MR compatible mock loop, closely resembles the pulmonary circulation thereby providing a controllable environment for hemodynamic studies.
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Affiliation(s)
- Maartje Conijn
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, 3584 EA, NETHERLANDS
| | - Lieke Wintermans
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3584 EA , NETHERLANDS
| | - Rutger Metselaar
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Janna Ruisch
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Eva Bax
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Carmen van Egmond
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA , NETHERLANDS
| | - Ben Nieuwenstein
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Evangeline Warmerdam
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Gregor Krings
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
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11
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Sadeghi R, Tomka B, Khodaei S, Daeian M, Gandhi K, Garcia J, Keshavarz-Motamed Z. Impact of extra-anatomical bypass on coarctation fluid dynamics using patient-specific lumped parameter and Lattice Boltzmann modeling. Sci Rep 2022; 12:9718. [PMID: 35690596 PMCID: PMC9188592 DOI: 10.1038/s41598-022-12894-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 04/11/2022] [Indexed: 01/28/2023] Open
Abstract
Accurate hemodynamic analysis is not only crucial for successful diagnosis of coarctation of the aorta (COA), but intervention decisions also rely on the hemodynamics assessment in both pre and post intervention states to minimize patient risks. Despite ongoing advances in surgical techniques for COA treatments, the impacts of extra-anatomic bypass grafting, a surgical technique to treat COA, on the aorta are not always benign. Our objective was to investigate the impact of bypass grafting on aortic hemodynamics. We investigated the impact of bypass grafting on aortic hemodynamics using a patient-specific computational-mechanics framework in three patients with COA who underwent bypass grafting. Our results describe that bypass grafting improved some hemodynamic metrics while worsened the others: (1) Doppler pressure gradient improved (decreased) in all patients; (2) Bypass graft did not reduce the flow rate substantially through the COA; (3) Systemic arterial compliance increased in patients #1 and 3 and didn't change (improve) in patient 3; (4) Hypertension got worse in all patients; (5) The flow velocity magnitude improved (reduced) in patient 2 and 3 but did not improve significantly in patient 1; (6) There were elevated velocity magnitude, persistence of vortical flow structure, elevated turbulence characteristics, and elevated wall shear stress at the bypass graft junctions in all patients. We concluded that bypass graft may lead to pseudoaneurysm formation and potential aortic rupture as well as intimal hyperplasia due to the persistent abnormal and irregular aortic hemodynamics in some patients. Moreover, post-intervention, exposures of endothelial cells to high shear stress may lead to arterial remodeling, aneurysm, and rupture.
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Affiliation(s)
- Reza Sadeghi
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Benjamin Tomka
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Seyedvahid Khodaei
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - MohammadAli Daeian
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Krishna Gandhi
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Julio Garcia
- grid.489011.50000 0004 0407 3514Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute of Alberta, Calgary, AB Canada ,grid.22072.350000 0004 1936 7697Department of Radiology, University of Calgary, Calgary, AB Canada ,grid.22072.350000 0004 1936 7697Department of Cardiac Sciences, University of Calgary, Calgary, AB Canada ,grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, AB Canada
| | - Zahra Keshavarz-Motamed
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON ,grid.25073.330000 0004 1936 8227School of Biomedical Engineering, McMaster University, Hamilton, ON Canada ,grid.25073.330000 0004 1936 8227School of Computational Science and Engineering, McMaster University, Hamilton, ON Canada
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12
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Hou Q, Tao K, Du T, Wei H, Zhang H, Chen S, Pan Y, Qiao A. A computational analysis of potential aortic dilation induced by the hemodynamic effects of bicuspid aortic valve phenotypes. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 220:106811. [PMID: 35447428 DOI: 10.1016/j.cmpb.2022.106811] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 03/01/2022] [Accepted: 04/10/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND OBJECTIVES The bicuspid aortic valve (BAV) is a major risk factor for the progression of aortic dilation (AD) because of the induced abnormal blood flow environment in aorta. The differences in the development of AD induced by BAV phenotypes remains unclear. Therefore, the objective of this study was to assess the potential locations of AD induced by different phenotypes of BAV. The different effects of opening orifice area and leaflet orientation on ascending aortic hemodynamics in Type-1 BAV was investigated by means of numerical simulation. METHODS Finite element dynamic analysis was performed on tricuspid aortic valve (TAV) and BAV models to simulate the motion of the leaflets and obtain the geometrical characteristics of AV at peak systole as a reference, which were used for aortic models. Then, four sets of aortic fluid models were designed according to the leaflet fusion types [TAV; BAV (left-right-coronary cusp fusion, LR; right-non-coronary cusp fusion, RN; left-non-coronary cusp fusion, LN)], and the computational fluid dynamics method was applied to compare the hemodynamic differences within the aorta at peak systole. RESULTS The maximum opening area of BAV was significantly reduced, resulting in alterations in aortic hemodynamics compared with TAV. The velocity streamlines were essentially parallel to the aortic wall in TAV. The average pressure and wall shear stress in aorta tend to be stable. In contrary, the eccentricity of BAV orifice jet resulted in high-velocity flow directed toward the ascending aorta (AA) wall and aortic arch for LR and LN; RN features an asymmetrical velocity distribution toward the outer bend of the middle AA, and eccentric flow tends to impact the distal AA. As the flow angle is associated with distinct flow impingement locations, different degrees of WSS and pressure concentration occur along the aortic wall from the AA to the aortic arch in three BAV types. CONCLUSIONS The BAV morphotype affects the aortic hemodynamics, and the abnormal blood flow associated with BAV may play a role in AD. The different BAV phenotypes determine the direction of blood flow jet and change the expression of dilation. LR is likely to cause dilation of the tubular AA; RN results in dilation of the middle AA to proximal aortic arch; and LN causes an increased incidence of the tubular AA and the proximal aortic arch.
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Affiliation(s)
- Qianwen Hou
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Keyi Tao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Tianming Du
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
| | - Hongge Wei
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Honghui Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Shiliang Chen
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Youlian Pan
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Aike Qiao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
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13
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Liu X, Aslan S, Kim B, Warburton L, Jackson D, Muhuri A, Subramanian A, Mass P, Cleveland V, Loke YH, Hibino N, Olivieri L, Krieger A. Computational Fontan Analysis: Preserving Accuracy While Expediting Workflow. World J Pediatr Congenit Heart Surg 2022; 13:293-301. [PMID: 35446218 DOI: 10.1177/21501351211073619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Background: Postoperative outcomes of the Fontan operation have been linked to geometry of the cavopulmonary pathway, including graft shape after implantation. Computational fluid dynamics (CFD) simulations are used to explore different surgical options. The objective of this study is to perform a systematic in vitro validation for investigating the accuracy and efficiency of CFD simulation to predict Fontan hemodynamics. Methods: CFD simulations were performed to measure indexed power loss (iPL) and hepatic flow distribution (HFD) in 10 patient-specific Fontan models, with varying mesh and numerical solvers. The results were compared with a novel in vitro flow loop setup with 3D printed Fontan models. A high-resolution differential pressure sensor was used to measure the pressure drop for validating iPL predictions. Microparticles with particle filtering system were used to measure HFD. The computational time was measured for a representative Fontan model with different mesh sizes and numerical solvers. Results: When compared to in vitro setup, variations in CFD mesh sizes had significant effect on HFD (P = .0002) but no significant impact on iPL (P = .069). Numerical solvers had no significant impact in both iPL (P = .50) and HFD (P = .55). A transient solver with 0.5 mm mesh size requires computational time 100 times more than a steady solver with 2.5 mm mesh size to generate similar results. Conclusions: The predictive value of CFD for Fontan planning can be validated against an in vitro flow loop. The prediction accuracy can be affected by the mesh size, model shape complexity, and flow competition.
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Affiliation(s)
- Xiaolong Liu
- Department of Mechanical Engineering, 1466Johns Hopkins University, Baltimore, MD, USA.,Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Seda Aslan
- Department of Mechanical Engineering, 1466Johns Hopkins University, Baltimore, MD, USA.,Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Byeol Kim
- Department of Mechanical Engineering, 1466Johns Hopkins University, Baltimore, MD, USA.,Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Linnea Warburton
- Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Derrick Jackson
- Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Abir Muhuri
- Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Akshay Subramanian
- Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
| | - Paige Mass
- Sheikh Zayed Institute for Pediatric Surgical Innovation, 8404Children's National Medical Center, Washington, DC, USA
| | - Vincent Cleveland
- Sheikh Zayed Institute for Pediatric Surgical Innovation, 8404Children's National Medical Center, Washington, DC, USA
| | - Yue-Hin Loke
- 8404Division of Cardiology, Children's National Medical Center, Washington, DC, USA
| | - Narutoshi Hibino
- 2462Department of Cardiac Surgery, University of Chicago/21880Advocate Children's Hospital, Chicago, IL, USA
| | - Laura Olivieri
- Sheikh Zayed Institute for Pediatric Surgical Innovation, 8404Children's National Medical Center, Washington, DC, USA.,8404Division of Cardiology, Children's National Medical Center, Washington, DC, USA
| | - Axel Krieger
- Department of Mechanical Engineering, 1466Johns Hopkins University, Baltimore, MD, USA.,Department of Mechanical Engineering, 1068University of Maryland, College Park, MD, USA
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14
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Kim B, Nguyen P, Loke YH, Cleveland V, Liu X, Mass P, Hibino N, Olivieri L, Krieger A. CorFix: Virtual Reality Cardiac Surgical Planning Software for Designing Patient-Specific Vascular Grafts: Development and Pilot Usability Study (Preprint). JMIR Cardio 2021; 6:e35488. [PMID: 35713940 PMCID: PMC9250062 DOI: 10.2196/35488] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 05/05/2022] [Accepted: 05/17/2022] [Indexed: 11/17/2022] Open
Abstract
Background Patients with single ventricle heart defects receive 3 stages of operations culminating in the Fontan procedure. During the Fontan procedure, a vascular graft is sutured between the inferior vena cava and pulmonary artery to divert deoxygenated blood flow to the lungs via passive flow. Customizing the graft configuration can maximize the long-term benefits. However, planning patient-specific procedures has several challenges, including the ability for physicians to customize grafts and evaluate their hemodynamic performance. Objective The aim of this study was to develop a virtual reality (VR) Fontan graft modeling and evaluation software for physicians. A user study was performed to achieve 2 additional goals: (1) to evaluate the software when used by medical doctors and engineers, and (2) to explore the impact of viewing hemodynamic simulation results in numerical and graphical formats. Methods A total of 5 medical professionals including 4 physicians (1 fourth-year resident, 1 third-year cardiac fellow, 1 pediatric intensivist, and 1 pediatric cardiac surgeon) and 1 biomedical engineer voluntarily participated in the study. The study was pre-scripted to minimize the variability of the interactions between the experimenter and the participants. All participants were trained to use the VR gear and our software, CorFix. Each participant designed 1 bifurcated and 1 tube-shaped Fontan graft for a single patient. A hemodynamic performance evaluation was then completed, allowing the participants to further modify their tube-shaped design. The design time and hemodynamic performance for each graft design were recorded. At the end of the study, all participants were provided surveys to evaluate the usability and learnability of the software and rate the intensity of VR sickness. Results The average times for creating 1 bifurcated and 1 tube-shaped graft after a single 10-minute training session were 13.40 and 5.49 minutes, respectively, with 3 out 5 bifurcated and 1 out of 5 tube-shaped graft designs being in the benchmark range of hepatic flow distribution. Reviewing hemodynamic performance results and modifying the tube-shaped design took an average time of 2.92 minutes. Participants who modified their tube-shaped graft designs were able to improve the nonphysiologic wall shear stress (WSS) percentage by 7.02%. All tube-shaped graft designs improved the WSS percentage compared to the native surgical case of the patient. None of the designs met the benchmark indexed power loss. Conclusions VR graft design software can quickly be taught to physicians with no engineering background or VR experience. Improving the CorFix system could improve performance of the users in customizing and optimizing grafts for patients. With graphical visualization, physicians were able to improve WSS percentage of a tube-shaped graft, lowering the chance of thrombosis. Bifurcated graft designs showed potential strength in better flow split to the lungs, reducing the risk for pulmonary arteriovenous malformations.
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Affiliation(s)
- Byeol Kim
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Phong Nguyen
- Department of Computer Science, University of Maryland, College Park, MD, United States
| | - Yue-Hin Loke
- Division of Cardiology, Children's National Hospital, Washington, DC, United States
| | - Vincent Cleveland
- Division of Cardiology, Children's National Hospital, Washington, DC, United States
| | - Xiaolong Liu
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Paige Mass
- Division of Cardiology, Children's National Hospital, Washington, DC, United States
| | - Narutoshi Hibino
- Department of Surgery, University of Chicago, Chicago, IL, United States
| | - Laura Olivieri
- Division of Cardiology, Children's National Hospital, Washington, DC, United States
| | - Axel Krieger
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
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15
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Mandell JG, Loke YH, Mass PN, Cleveland V, Delaney M, Opfermann J, Aslan S, Krieger A, Hibino N, Olivieri LJ. Altered hemodynamics by 4D flow cardiovascular magnetic resonance predict exercise intolerance in repaired coarctation of the aorta: an in vitro study. J Cardiovasc Magn Reson 2021; 23:99. [PMID: 34482836 PMCID: PMC8420072 DOI: 10.1186/s12968-021-00796-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/14/2021] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Coarctation of the aorta (CoA) is associated with decreased exercise capacity despite successful repair. Altered flow patterns have been identified due to abnormal aortic arch geometry. Our previous work demonstrated aorta size mismatch to be associated with exercise intolerance in this population. In this study, we studied aortic flow patterns during simulations of exercise in repaired CoA using 4D flow cardiovascular magnetic resonance (CMR) using aortic replicas connected to an in vitro flow pump and correlated findings with exercise stress test results to identify biomarkers of exercise intolerance. METHODS Patients with CoA repair were retrospectively analyzed after CMR and exercise stress test. Each aorta was manually segmented and 3D printed. Pressure gradient measurements from ascending aorta (AAo) to descending aorta (DAo) and 4D flow CMR were performed during simulations of rest and exercise using a mock circulatory flow loop. Changes in wall shear stress (WSS) and secondary flow formation (vorticity and helicity) from rest to exercise were quantified, as well as estimated DAo Reynolds number. Parameters were correlated with percent predicted peak oxygen consumption (VO2max) and aorta size mismatch (DAAo/DDAo). RESULTS Fifteen patients were identified (VO2max 47 to 126% predicted). Pressure gradient did not correlate with VO2max at rest or exercise. VO2max correlated positively with the change in peak vorticity (R = 0.55, p = 0.03), peak helicity (R = 0.54, p = 0.04), peak WSS in the AAo (R = 0.68, p = 0.005) and negatively with peak WSS in the DAo (R = - 0.57, p = 0.03) from rest to exercise. DAAo/DDAo correlated strongly with change in vorticity (R = - 0.38, p = 0.01), helicity (R = - 0.66, p = 0.007), and WSS in the AAo (R = - 0.73, p = 0.002) and DAo (R = 0.58, p = 0.02). Estimated DAo Reynolds number negatively correlated with VO2max for exercise (R = - 0.59, p = 0.02), but not rest (R = - 0.28, p = 0.31). Visualization of streamline patterns demonstrated more secondary flow formation in aortic arches with better exercise capacity, larger DAo, and lower Reynolds number. CONCLUSIONS There are important associations between secondary flow characteristics and exercise capacity in repaired CoA that are not captured by traditional pressure gradient, likely due to increased turbulence and inefficient flow. These 4D flow CMR parameters are a target of investigation to identify optimal aortic arch geometry and improve long term clinical outcomes after CoA repair.
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Affiliation(s)
- Jason G Mandell
- Division of Cardiology, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA.
| | - Yue-Hin Loke
- Division of Cardiology, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
| | - Paige N Mass
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
| | - Vincent Cleveland
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
| | - Marc Delaney
- Division of Cardiology, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
| | - Justin Opfermann
- Department of Mechanical Engineering, Johns Hopkins University, Latrobe Hall 223, 3400 North Charles St, Baltimore, MD, 21218, USA
| | - Seda Aslan
- Department of Mechanical Engineering, Johns Hopkins University, Latrobe Hall 223, 3400 North Charles St, Baltimore, MD, 21218, USA
| | - Axel Krieger
- Department of Mechanical Engineering, Johns Hopkins University, Latrobe Hall 223, 3400 North Charles St, Baltimore, MD, 21218, USA
| | - Narutoshi Hibino
- Section of Cardiac Surgery, Department of Surgery, University of Chicago, 5841 S Maryland Avenue, Chicago, IL, 60637, USA
- Section of Cardiac Surgery, Department of Surgery, Advocate Children's Hospital, 4440 West 95th Street, Oak Lawn, IL, 60453, USA
| | - Laura J Olivieri
- Division of Cardiology, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
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16
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Mandell JG, Loke YH, Mass PN, Opfermann J, Cleveland V, Aslan S, Hibino N, Krieger A, Olivieri LJ. Aorta size mismatch predicts decreased exercise capacity in patients with successfully repaired coarctation of the aorta. J Thorac Cardiovasc Surg 2021; 162:183-192.e2. [PMID: 33131888 DOI: 10.1016/j.jtcvs.2020.09.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 09/09/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Coarctation of the aorta (CoA) is associated with decreased exercise capacity despite successful repair with no residual stenosis; however, the hemodynamic mechanism remains unknown. This study aims to correlate aortic arch geometry with exercise capacity in patients with successfully repaired CoA and explain hemodynamic changes using 3-dimensional-printed aorta models in a mock circulatory flow loop. METHODS A retrospective chart review identified patients with CoA repair who had cardiac magnetic resonance imaging and an exercise stress test. Measurements included aorta diameters, arch height to diameter ratio, left ventricular function, and percent descending aorta (%DAo) flow. Each aorta was printed 3-dimensionally for the flow loop. Flow and pressure were measured at the ascending aorta (AAo) and DAo during simulated rest and exercise. Measurements were correlated with percent predicted peak oxygen consumption (VO2 max). RESULTS Fifteen patients (mean age 26.8 ± 8.6 years) had a VO2 max between 47% and 126% predicted (mean 92 ± 20%) with normal left ventricular function. DAo diameter and %DAo flow positively correlated with VO2 (P = .007 and P = .04, respectively). AAo to DAo diameter ratio (DAAo/DDAo) negatively correlated with VO2 (P < .001). From flow loop simulations, the ratio of %DAo flow in exercise to rest negatively correlated with VO2 (P = .02) and positively correlated with DAAo/DDAo (P < .01). CONCLUSIONS This study suggests aorta size mismatch (DAAo/DDAo) is a novel, clinically important measurement predicting exercise capacity in patients with successful CoA repair, likely due to increased resistance and altered flow distribution. Aorta size mismatch and %DAo flow are targets for further clinical evaluation in repaired CoA.
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Affiliation(s)
- Jason G Mandell
- Division of Cardiology, Children's National Hospital, Washington, DC.
| | - Yue-Hin Loke
- Division of Cardiology, Children's National Hospital, Washington, DC
| | - Paige N Mass
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC
| | - Justin Opfermann
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC
| | - Vincent Cleveland
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC
| | - Seda Aslan
- Department of Mechanical Engineering, University of Maryland, College Park, Md
| | - Narutoshi Hibino
- Section of Cardiac Surgery, Department of Surgery, University of Chicago/Advocate Children's Hospital Chicago, Ill
| | - Axel Krieger
- Department of Mechanical Engineering, University of Maryland, College Park, Md
| | - Laura J Olivieri
- Division of Cardiology, Children's National Hospital, Washington, DC; Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC
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17
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Sotelo J, Valverde I, Martins D, Bonnet D, Boddaert N, Pushparajan K, Uribe S, Raimondi F. Impact of aortic arch curvature in flow haemodynamics in patients with transposition of the great arteries after arterial switch operation. Eur Heart J Cardiovasc Imaging 2021; 23:402-411. [PMID: 33517430 DOI: 10.1093/ehjci/jeaa416] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/20/2020] [Indexed: 11/13/2022] Open
Abstract
AIMS In this study, we will describe a comprehensive haemodynamic analysis and its relationship to the dilation of the aorta in transposition of the great artery (TGA) patients post-arterial switch operation (ASO) and controls using 4D-flow magnetic resonance imaging (MRI) data. METHODS AND RESULTS Using 4D-flow MRI data of 14 TGA young patients and 8 age-matched normal controls obtained with 1.5 T GE-MR scanner, we evaluate 3D maps of 15 different haemodynamics parameters in six regions; three of them in the aortic root and three of them in the ascending aorta (anterior-left, -right, and posterior for both cases) to find its relationship with the aortic arch curvature and root dilation. Differences between controls and patients were evaluated using Mann-Whitney U test, and the relationship with the curvature was accessed by unpaired t-test. For statistical significance, we consider a P-value of 0.05. The aortic arch curvature was significantly different between patients 46.238 ± 5.581 m-1 and controls 41.066 ± 5.323 m-1. Haemodynamic parameters as wall shear stress circumferential (WSS-C), and eccentricity (ECC), were significantly different between TGA patients and controls in both the root and ascending aorta regions. The distribution of forces along the ascending aorta is highly inhomogeneous in TGA patients. We found that the backward velocity (B-VEL), WSS-C, velocity angle (VEL-A), regurgitation fraction (RF), and ECC are highly correlated with the aortic arch curvature and root dilatation. CONCLUSION We have identified six potential biomarkers (B-VEL, WSS-C, VEL-A, RF, and ECC), which may be helpful for follow-up evaluation and early prediction of aortic root dilatation in this patient population.
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Affiliation(s)
- Julio Sotelo
- School of Biomedical Engineering, Universidad de Valparaíso, General Cruz 222, 236-2905 Valparaíso, Chile.,Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4869, Macul, Santiago 832-0000, Chile.,Department of Electrical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, Santiago 832-0000, Chile.,Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile
| | - Israel Valverde
- School of Biomedical Engineering & Imaging Sciences, King's College London, Lambeth Wing St, Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.,Paediatric Cardiology, Evelina London Children's Hospital, St. Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.,Pediatric Cardiology Unit, Institute of Biomedicine of Seville (IBIS), CIBER-CV, Hospital Virgen de Rocio/CSIC/University of Seville, Av. Manuel Siurot, S/n, 41013 Seville, Spain
| | - Duarte Martins
- Unité médico-chirurgicale de cardiologie congénitale et pédiatrique, centre de référence des maladies cardiaques congénitales complexes-M3C, Hôpital universitaire Necker-Enfants Malades, 149 Rue de Sèvres, 75015 Paris, France.,Pediatric Cardiology Department, Hospital de Santa Cruz, Centro Hospitalar Lisboa Ocidental. Av. Prof. Dr. Reinaldo dos Santos, 2790-134 Carnaxide, Lisbon, Portugal
| | - Damien Bonnet
- Unité médico-chirurgicale de cardiologie congénitale et pédiatrique, centre de référence des maladies cardiaques congénitales complexes-M3C, Hôpital universitaire Necker-Enfants Malades, 149 Rue de Sèvres, 75015 Paris, France
| | - Nathalie Boddaert
- Pediatric Radiology Unit, Hôpital universitaire Necker-Enfants Malades, 149 Rue de Sèvres, 75015, Paris, France
| | - Kuberan Pushparajan
- School of Biomedical Engineering & Imaging Sciences, King's College London, Lambeth Wing St, Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.,Paediatric Cardiology, Evelina London Children's Hospital, St. Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Sergio Uribe
- Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4869, Macul, Santiago 832-0000, Chile.,Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile.,Department of Radiology, School of Medicine, Pontificia Universidad Católica de Chile, Avda. Libertador Bernando O'Higgins 340, 833-1150 Santiago, Chile
| | - Francesca Raimondi
- Paediatric Cardiology, Evelina London Children's Hospital, St. Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.,Unité médico-chirurgicale de cardiologie congénitale et pédiatrique, centre de référence des maladies cardiaques congénitales complexes-M3C, Hôpital universitaire Necker-Enfants Malades, 149 Rue de Sèvres, 75015 Paris, France.,Pediatric Radiology Unit, Hôpital universitaire Necker-Enfants Malades, 149 Rue de Sèvres, 75015, Paris, France
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18
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Hemodynamics alteration in patient-specific dilated ascending thoracic aortas with tricuspid and bicuspid aortic valves. J Biomech 2020; 110:109954. [DOI: 10.1016/j.jbiomech.2020.109954] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 01/03/2023]
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19
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McGurk KA, Owen B, Watson WD, Nethononda RM, Cordell HJ, Farrall M, Rider OJ, Watkins H, Revell A, Keavney BD. Heritability of haemodynamics in the ascending aorta. Sci Rep 2020; 10:14356. [PMID: 32873833 PMCID: PMC7463029 DOI: 10.1038/s41598-020-71354-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/25/2020] [Indexed: 01/27/2023] Open
Abstract
Blood flow in the vasculature can be characterised by dimensionless numbers commonly used to define the level of instabilities in the flow, for example the Reynolds number, Re. Haemodynamics play a key role in cardiovascular disease (CVD) progression. Genetic studies have identified mechanosensitive genes with causal roles in CVD. Given that CVD is highly heritable and abnormal blood flow may increase risk, we investigated the heritability of fluid metrics in the ascending aorta calculated using patient-specific data from cardiac magnetic resonance (CMR) imaging. 341 participants from 108 British Caucasian families were phenotyped by CMR and genotyped for 557,124 SNPs. Flow metrics were derived from the CMR images to provide some local information about blood flow in the ascending aorta, based on maximum values at systole at a single location, denoted max, and a 'peak mean' value averaged over the area of the cross section, denoted pm. Heritability was estimated using pedigree-based (QTDT) and SNP-based (GCTA-GREML) methods. Estimates of Reynolds number based on spatially averaged local flow during systole showed substantial heritability ([Formula: see text], [Formula: see text]), while the estimated heritability for Reynolds number calculated using the absolute local maximum velocity was not statistically significant (12-13%; [Formula: see text]). Heritability estimates of the geometric quantities alone; e.g. aortic diameter ([Formula: see text], [Formula: see text]), were also substantially heritable, as described previously. These findings indicate the potential for the discovery of genetic factors influencing haemodynamic traits in large-scale genotyped and phenotyped cohorts where local spatial averaging is used, rather than instantaneous values. Future Mendelian randomisation studies of aortic haemodynamic estimates, which are swift to derive in a clinical setting, will allow for the investigation of causality of abnormal blood flow in CVD.
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Affiliation(s)
- Kathryn A McGurk
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Benjamin Owen
- Department of Mechanical, Aerospace and Civil Engineering, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- School of Engineering, Multiscale Thermofluids Institute, University of Edinburgh, Edinburgh, UK
| | - William D Watson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Richard M Nethononda
- Division of Cardiology, Chris Hani Baragwanath Hospital, Soweto and the University of Witwatersrand, Johannesburg, South Africa
| | - Heather J Cordell
- Population Health Sciences Institute, Faculty of Medical Sciences, Newcastle University, International Centre for Life, Newcastle upon Tyne, UK
| | - Martin Farrall
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Oliver J Rider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Alistair Revell
- Department of Mechanical, Aerospace and Civil Engineering, Faculty of Science and Engineering, University of Manchester, Manchester, UK
| | - Bernard D Keavney
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
- Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
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20
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Jayendiran R, Condemi F, Campisi S, Viallon M, Croisille P, Avril S. Computational prediction of hemodynamical and biomechanical alterations induced by aneurysm dilatation in patient-specific ascending thoracic aortas. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3326. [PMID: 32087044 DOI: 10.1002/cnm.3326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 02/15/2020] [Indexed: 06/10/2023]
Abstract
The aim of the present work is to propose a robust computational framework combining computational fluid dynamics (CFD) and 4D flow MRI to predict the progressive changes in hemodynamics and wall rupture index (RPI) induced by aortic morphological evolutions in patients harboring ascending thoracic aortic aneurysms (ATAAs). An analytical equation has been proposed to predict the aneurysm progression based on age, sex, and body surface area. Parameters such as helicity, wall shear stress (WSS), time-averaged WSS, oscillatory shear index, relative residence time, and viscosity were evaluated for two patients at different stages of aneurysm growth, and compared with age-sex-matched healthy subjects. The study shows that evolution of hemodynamics and RPI, despite being very slow in ATAAs, is strongly affected by morphological alterations and, in turn could impact biomechanical factors and aortic mechanobiology. An aspect of the current work is that the patient-specific 4D MRI data sets were obtained with a follow-up of 1 year and the measured time-averaged velocity maps and flow eccentricity were compared with the CFD simulation for validation. The computational framework presented here is capable of capturing the blood flow patterns and the hemodynamic descriptors during the various stages of aneurysm growth. Further investigations will be conducted in order to verify these results on a larger cohort of patients and with long follow-up times to finally elucidate the link between deranged hemodynamics, AA geometry, and wall mechanical properties in ATAAs.
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Affiliation(s)
- Raja Jayendiran
- Mines Saint-Etienne, Université de Lyon, INSERM, U1059, SAINBIOSE, Saint-Etienne F-42023, France
| | | | - Salvatore Campisi
- Department of Cardiovascular Surgery, University Hospital of Saint-Etienne, Saint-Etienne, France
| | - Magalie Viallon
- UJM-Saint-Etienne, INSA, CNRS UMR 5520, INSERM U1206, CREATIS, Université de Lyon, Saint-Etienne, France
- Department of Radiology, University Hospital of Saint-Etienne, Saint-Etienne, France
| | - Pierre Croisille
- UJM-Saint-Etienne, INSA, CNRS UMR 5520, INSERM U1206, CREATIS, Université de Lyon, Saint-Etienne, France
- Department of Radiology, University Hospital of Saint-Etienne, Saint-Etienne, France
| | - Stéphane Avril
- Mines Saint-Etienne, Université de Lyon, INSERM, U1059, SAINBIOSE, Saint-Etienne F-42023, France
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21
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Palen RL, Deurvorst QS, Kroft LJ, Boogaard PJ, Hazekamp MG, Blom NA, Lamb HJ, Westenberg JJ, Roest AA. Altered Ascending Aorta Hemodynamics in Patients After Arterial Switch Operation for Transposition of the Great Arteries. J Magn Reson Imaging 2019; 51:1105-1116. [DOI: 10.1002/jmri.26934] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 11/10/2022] Open
Affiliation(s)
- Roel L.F. Palen
- Division of Pediatric Cardiology, Department of PediatricsLeiden University Medical Center Leiden The Netherlands
| | - Quirine S. Deurvorst
- Division of Pediatric Cardiology, Department of PediatricsLeiden University Medical Center Leiden The Netherlands
| | - Lucia J.M. Kroft
- Department of RadiologyLeiden University Medical Center Leiden The Netherlands
| | - Pieter J. Boogaard
- Department of RadiologyLeiden University Medical Center Leiden The Netherlands
| | - Mark G. Hazekamp
- Department of Cardiothoracic SurgeryLeiden University Medical Center Leiden The Netherlands
| | - Nico A. Blom
- Division of Pediatric Cardiology, Department of PediatricsLeiden University Medical Center Leiden The Netherlands
| | - Hildo J. Lamb
- Department of RadiologyLeiden University Medical Center Leiden The Netherlands
| | - Jos J.M. Westenberg
- Department of RadiologyLeiden University Medical Center Leiden The Netherlands
| | - Arno A.W. Roest
- Division of Pediatric Cardiology, Department of PediatricsLeiden University Medical Center Leiden The Netherlands
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22
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Evaluation of 4D flow MRI-based non-invasive pressure assessment in aortic coarctations. J Biomech 2019; 94:13-21. [PMID: 31326119 DOI: 10.1016/j.jbiomech.2019.07.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 06/12/2019] [Accepted: 07/04/2019] [Indexed: 12/20/2022]
Abstract
Severity of aortic coarctation (CoA) is currently assessed by estimating trans-coarctation pressure drops through cardiac catheterization or echocardiography. In principle, more detailed information could be obtained non-invasively based on space- and time-resolved magnetic resonance imaging (4D flow) data. Yet the limitations of this imaging technique require testing the accuracy of 4D flow-derived hemodynamic quantities against other methodologies. With the objective of assessing the feasibility and accuracy of this non-invasive method to support the clinical diagnosis of CoA, we developed an algorithm (4DF-FEPPE) to obtain relative pressure distributions from 4D flow data by solving the Poisson pressure equation. 4DF-FEPPE was tested against results from a patient-specific fluid-structure interaction (FSI) simulation, whose patient-specific boundary conditions were prescribed based on 4D flow data. Since numerical simulations provide noise-free pressure fields on fine spatial and temporal scales, our analysis allowed to assess the uncertainties related to 4D flow noise and limited resolution. 4DF-FEPPE and FSI results were compared on a series of cross-sections along the aorta. Bland-Altman analysis revealed very good agreement between the two methodologies in terms of instantaneous data at peak systole, end-diastole and time-averaged values: biases (means of differences) were +0.4 mmHg, -1.1 mmHg and +0.6 mmHg, respectively. Limits of agreement (2 SD) were ±0.978 mmHg, ±1.06 mmHg and ±1.97 mmHg, respectively. Peak-to-peak and maximum trans-coarctation pressure drops obtained with 4DF-FEPPE differed from FSI results by 0.75 mmHg and -1.34 mmHg respectively. The present study considers important validation aspects of non-invasive pressure difference estimation based on 4D flow MRI, showing the potential of this technology to be more broadly applied to the clinical practice.
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23
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Biglino G, Milano EG, Capelli C, Wray J, Shearn AI, Caputo M, Bucciarelli-Ducci C, Taylor AM, Schievano S. Three-dimensional printing in congenital heart disease: Considerations on training and clinical implementation from a teaching session. Int J Artif Organs 2019; 42:595-599. [PMID: 31104546 DOI: 10.1177/0391398819849074] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In light of growing interest for three-dimensional printing technology in the cardiovascular community, this study focused on exploring the possibilities of providing training for cardiovascular three-dimensional printing in the context of a relevant international congress and providing considerations on the delivery of such courses. As a second objective, the study sought to capture preferences in relation to three-dimensional printing uses and set-ups from those attending the training session. A survey was administered to n = 30 professionals involved or interested in three-dimensional printing cardiovascular models following a specialised teaching session. Survey results suggest the potential for split training sessions, with a broader introduction for those with no prior experience in three-dimensional printing followed by a more in-depth and hands-on session. All participants agreed on the potential of the technology in all its applications, particularly for aiding decision-making around complex surgical or interventional cases. When exploring setting up an in-house three-dimensional printing service, the majority of participants reported that their centre was already equipped with an in-house facility or expressed a desire that such a facility should be available, with a minority preferring consigning models to an external third party for printing.
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Affiliation(s)
- Giovanni Biglino
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Elena G Milano
- Institute of Cardiovascular Science, University College London, London, UK.,Department of Surgery, Dentistry, Paediatrics and Obstetrics/Gynaecology, University of Verona, Verona, Italy
| | - Claudio Capelli
- Institute of Cardiovascular Science, University College London, London, UK.,Cardiorespiratory Division, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Jo Wray
- Cardiorespiratory Division, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Andrew Iu Shearn
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol, UK
| | - Massimo Caputo
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol, UK.,University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Chiara Bucciarelli-Ducci
- Bristol Heart Institute, Bristol Medical School, University of Bristol, Bristol, UK.,University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Andrew M Taylor
- Institute of Cardiovascular Science, University College London, London, UK.,Cardiorespiratory Division, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Silvia Schievano
- Institute of Cardiovascular Science, University College London, London, UK.,Cardiorespiratory Division, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
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24
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Puiseux T, Sewonu A, Meyrignac O, Rousseau H, Nicoud F, Mendez S, Moreno R. Reconciling PC-MRI and CFD: An in-vitro study. NMR IN BIOMEDICINE 2019; 32:e4063. [PMID: 30747461 DOI: 10.1002/nbm.4063] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 11/16/2018] [Accepted: 12/18/2018] [Indexed: 05/25/2023]
Abstract
Several well-resolved 4D Flow MRI acquisitions of an idealized rigid flow phantom featuring an aneurysm, a curved channel as well as a bifurcation were performed under pulsatile regime. The resulting hemodynamics were processed to remove MRI artifacts. Subsequently, they were compared with CFD predictions computed on the same flow domain, using an in-house high-order low dissipative flow solver. Results show that reaching a good agreement is not straightforward but requires proper treatments of both techniques. Several sources of discrepancies are highlighted and their impact on the final correlation evaluated. While a very poor correlation (r2 = 0.63) is found in the entire domain between raw MRI and CFD data, correlation as high as r2 = 0.97 is found when artifacts are removed by post-processing the MR data and down sampling the CFD results to match the MRI spatial and temporal resolutions. This work demonstrates that, in a well-controlled environment, both PC-MRI and CFD might bring reliable and correlated flow quantities when a proper methodology to reduce the errors is followed.
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Affiliation(s)
- Thomas Puiseux
- IMAG, Univ Montpellier, CNRS, Montpellier, France
- ALARA Expertise, Strasbourg, France
| | - Anou Sewonu
- ALARA Expertise, Strasbourg, France
- I2MC, INSERM U1048, Toulouse, France
| | - Olivier Meyrignac
- I2MC, INSERM U1048, Toulouse, France
- Department of Radiology, CHU de Toulouse, Toulouse, France
| | - Hervé Rousseau
- I2MC, INSERM U1048, Toulouse, France
- Department of Radiology, CHU de Toulouse, Toulouse, France
| | | | - Simon Mendez
- IMAG, Univ Montpellier, CNRS, Montpellier, France
| | - Ramiro Moreno
- ALARA Expertise, Strasbourg, France
- I2MC, INSERM U1048, Toulouse, France
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25
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Milano EG, Capelli C, Wray J, Biffi B, Layton S, Lee M, Caputo M, Taylor AM, Schievano S, Biglino G. Current and future applications of 3D printing in congenital cardiology and cardiac surgery. Br J Radiol 2018; 92:20180389. [PMID: 30325646 DOI: 10.1259/bjr.20180389] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Three-dimensional (3D) printing technology in congenital cardiology and cardiac surgery has experienced a rapid development over the last decade. In presence of complex cardiac and extra-cardiac anatomies, the creation of a physical, patient-specific model is attractive to most clinicians. However, at the present time, there is still a lack of strong scientific evidence of the benefit of 3D models in clinical practice and only qualitative evaluation of the models has been used to investigate their clinical use. 3D models can be printed in rigid or flexible materials, and the original size can be augmented depending on the application the models are needed for. The most common applications of 3D models at present include procedural planning of complex surgical or interventional cases, in vitro simulation for research purposes, training and communication with patients and families. The aim of this pictorial review is to describe the basic principles of this technology and present its current and future applications.
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Affiliation(s)
- Elena Giulia Milano
- 1 Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children , London , UK.,2 Department of Medicine, Section of Cardiology, University of Verona , Verona , Italy
| | - Claudio Capelli
- 1 Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children , London , UK
| | - Jo Wray
- 3 Cardiorespiratory Division, Great Ormond Street Hospital for Children, NHS Foundation Trust , London , UK
| | - Benedetta Biffi
- 1 Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children , London , UK
| | - Sofie Layton
- 3 Cardiorespiratory Division, Great Ormond Street Hospital for Children, NHS Foundation Trust , London , UK
| | - Matthew Lee
- 4 Bristol Heart Institute, Bristol Medical School, University of Bristol , Bristol , UK
| | - Massimo Caputo
- 4 Bristol Heart Institute, Bristol Medical School, University of Bristol , Bristol , UK
| | - Andrew M Taylor
- 1 Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children , London , UK
| | - Silvia Schievano
- 1 Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children , London , UK
| | - Giovanni Biglino
- 4 Bristol Heart Institute, Bristol Medical School, University of Bristol , Bristol , UK.,5 National Heart and Lung Institute, Imperial College London , London , United Kingdom
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26
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Stevens MC, Callaghan FM, Forrest P, Bannon PG, Grieve SM. A computational framework for adjusting flow during peripheral extracorporeal membrane oxygenation to reduce differential hypoxia. J Biomech 2018; 79:39-44. [PMID: 30104052 DOI: 10.1016/j.jbiomech.2018.07.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 06/29/2018] [Accepted: 07/24/2018] [Indexed: 01/27/2023]
Abstract
Peripheral veno-arterial extra corporeal membrane oxygenation (VA-ECMO) is an established technique for short-to-medium support of patients with severe cardiac failure. However, in patients with concomitant respiratory failure, the residual native circulation will provide deoxygenated blood to the upper body, and may cause differential hypoxemia of the heart and brain. In this paper, we present a general computational framework for the identification of differential hypoxemia risk in VA-ECMO patients. A range of different VA-ECMO patient scenarios for a patient-specific geometry and vascular resistance were simulated using transient computational fluid dynamics simulations, representing a clinically relevant range of values of stroke volume and ECMO flow. For this patient, regardless of ECMO flow rate, left ventricular stroke volumes greater than 28 mL resulted in all aortic arch branch vessels being perfused by poorly-oxygenated systemic blood sourced from the lungs. The brachiocephalic artery perfusion was almost entirely derived from blood from the left ventricle in all scenarios except for those with stroke volumes less than 5 mL. Our model therefore predicted a strong risk of differential hypoxemia in nearly all situations with some residual cardiac function for this combination of patient geometry and vascular resistance. This simulation highlights the potential value of modelling for optimising ECMO design and procedures, and for the practical utility for personalised approaches in the clinical use of ECMO.
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Affiliation(s)
- Michael Charles Stevens
- Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre, University of Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia; Sydney Medical School, University of Sydney, Camperdown, Australia
| | - Fraser M Callaghan
- Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre, University of Sydney, Australia; Sydney Medical School, University of Sydney, Camperdown, Australia
| | - Paul Forrest
- Sydney Medical School, University of Sydney, Camperdown, Australia; Department of Cardiothoracic Surgery, Royal Prince Alfred Hospital, Camperdown, Australia; Department of Anaesthetics, Royal Prince Alfred Hospital, Sydney, Australia
| | - Paul G Bannon
- Sydney Medical School, University of Sydney, Camperdown, Australia; Institute of Academic Surgery, Royal Prince Alfred Hospital, Sydney, Australia; The Baird Institute, Sydney, Australia
| | - Stuart M Grieve
- Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre, University of Sydney, Australia; Sydney Medical School, University of Sydney, Camperdown, Australia; Department of Radiology, Royal Prince Alfred Hospital, Camperdown, Australia.
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27
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Collier GJ, Kim M, Chung Y, Wild JM. 3D phase contrast MRI in models of human airways: Validation of computational fluid dynamics simulations of steady inspiratory flow. J Magn Reson Imaging 2018; 48:1400-1409. [DOI: 10.1002/jmri.26039] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 03/20/2018] [Indexed: 12/19/2022] Open
Affiliation(s)
- Guilhem J. Collier
- POLARIS, Unit of Academic Radiology, Department of Infection; Immunity and Cardiovascular Disease, University of Sheffield; Sheffield UK
| | - Minsuok Kim
- School of Engineering and Centre for Scientific Computing; University of Warwick; Coventry UK
| | - Yongmann Chung
- School of Engineering and Centre for Scientific Computing; University of Warwick; Coventry UK
| | - Jim M. Wild
- POLARIS, Unit of Academic Radiology, Department of Infection; Immunity and Cardiovascular Disease, University of Sheffield; Sheffield UK
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28
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Model-Based Therapy Planning Allows Prediction of Haemodynamic Outcome after Aortic Valve Replacement. Sci Rep 2017; 7:9897. [PMID: 28851875 PMCID: PMC5575088 DOI: 10.1038/s41598-017-03693-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/26/2017] [Indexed: 11/13/2022] Open
Abstract
Optimizing treatment planning is essential for advances in patient care and outcomes. Precisely tailored therapy for each patient remains a yearned-for goal. Cardiovascular modelling has the potential to simulate and predict the functional response before the actual intervention is performed. The objective of this study was to proof the validity of model-based prediction of haemodynamic outcome after aortic valve replacement. In a prospective study design virtual (model-based) treatment of the valve and the surrounding vasculature were performed alongside the actual surgical procedure (control group). The resulting predictions of anatomic and haemodynamic outcome based on information from magnetic resonance imaging before the procedure were compared to post-operative imaging assessment of the surgical control group in ten patients. Predicted vs. post-operative peak velocities across the valve were comparable (2.97 ± 1.12 vs. 2.68 ± 0.67 m/s; p = 0.362). In wall shear stress (17.3 ± 12.3 Pa vs. 16.7 ± 16.84 Pa; p = 0.803) and secondary flow degree (0.44 ± 0.32 vs. 0.49 ± 0.23; p = 0.277) significant linear correlations (p < 0.001) were found between predicted and post-operative outcomes. Between groups blood flow patterns showed good agreement (helicity p = 0.852, vorticity p = 0.185, eccentricity p = 0.333). Model-based therapy planning is able to accurately predict post-operative haemodynamics after aortic valve replacement. These validated virtual treatment procedures open up promising opportunities for individually targeted interventions.
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29
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Knoops PGM, Biglino G, Hughes AD, Parker KH, Xu L, Schievano S, Torii R. A Mock Circulatory System Incorporating a Compliant 3D-Printed Anatomical Model to Investigate Pulmonary Hemodynamics. Artif Organs 2017; 41:637-646. [PMID: 27925228 PMCID: PMC5384635 DOI: 10.1111/aor.12809] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/22/2016] [Accepted: 06/27/2016] [Indexed: 11/29/2022]
Abstract
A realistic mock circulatory system (MCS) could be a valuable in vitro testbed to study human circulatory hemodynamics. The objective of this study was to design a MCS replicating the pulmonary arterial circulation, incorporating an anatomically representative arterial model suitable for testing clinically relevant scenarios. A second objective of the study was to ensure the system's compatibility with magnetic resonance imaging (MRI) for additional measurements. A latex pulmonary arterial model with two generations of bifurcations was manufactured starting from a 3D-printed mold reconstructed from patient data. The model was incorporated into a MCS for in vitro hydrodynamic measurements. The setup was tested under physiological pulsatile flow conditions and results were evaluated using wave intensity analysis (WIA) to investigate waves traveling in the arterial system. Increased pulmonary vascular resistance (IPVR) was simulated as an example of one pathological scenario. Flow split between right and left pulmonary artery was found to be realistic (54 and 46%, respectively). No substantial difference in pressure waveform was observed throughout the various generations of bifurcations. Based on WIA, three main waves were identified in the main pulmonary artery (MPA), that is, forward compression wave, backward compression wave, and forward expansion wave. For IPVR, a rise in mean pressure was recorded in the MPA, within the clinical range of pulmonary arterial hypertension. The feasibility of using the MCS in the MRI scanner was demonstrated with the MCS running 2 h consecutively while acquiring preliminary MRI data. This study shows the development and verification of a pulmonary MCS, including an anatomically correct, compliant latex phantom. The setup can be useful to explore a wide range of hemodynamic questions, including the development of patient- and pathology-specific models, considering the ease and low cost of producing rapid prototyping molds, and the versatility of the setup for invasive and noninvasive (i.e., MRI) measurements.
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Affiliation(s)
- Paul G M Knoops
- UCL Institute of Child Health, London, United Kingdom
- Great Ormond Street Hospital for Children, NHS Trust, London, United Kingdom
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Giovanni Biglino
- Great Ormond Street Hospital for Children, NHS Trust, London, United Kingdom
- Bristol Heart Institute, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Alun D Hughes
- UCL Institute of Cardiovascular Science, London, United Kingdom
| | - Kim H Parker
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Linzhang Xu
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Silvia Schievano
- UCL Institute of Child Health, London, United Kingdom
- UCL Institute of Cardiovascular Science, London, United Kingdom
| | - Ryo Torii
- Department of Mechanical Engineering, University College London, London, United Kingdom
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30
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Aorta Ascending Aneurysm Analysis Using CFD Models towards Possible Anomalies. FLUIDS 2017. [DOI: 10.3390/fluids2020031] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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31
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Stevens MC, Callaghan FM, Forrest P, Bannon PG, Grieve SM. Flow mixing during peripheral veno-arterial extra corporeal membrane oxygenation - A simulation study. J Biomech 2017; 55:64-70. [PMID: 28262284 DOI: 10.1016/j.jbiomech.2017.02.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/17/2017] [Accepted: 02/11/2017] [Indexed: 11/15/2022]
Abstract
Peripheral veno-arterial extra-corporeal membrane oxygenation (ECMO) is an artificial circulation that supports patients with severe cardiac and respiratory failure. Differential hypoxia during ECMO support has been reported, and it has been suggested that it is due to the mixing of well-perfused retrograde ECMO flow and poorly-perfused antegrade left ventricle (LV) flow in the aorta. This study aims to quantify the relationship between ECMO support level and location of the mixing zone (MZ) of the ECMO and LV flows. Steady-state and transient computational fluid dynamics (CFD) simulations were performed using a patient-specific geometrical model of the aorta. A range of ECMO support levels (from 5% to 95% of total cardiac output) were evaluated. For ECMO support levels above 70%, the MZ was located in the aortic arch, resulting in perfusion of the arch branches with poorly perfused LV flow. The MZ location was stable over the cardiac cycle for high ECMO flows (>70%), but moved 5cm between systole and diastole for ECMO support level of 60%. This CFD approach has potential to improve individual patient care and ECMO design.
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Affiliation(s)
- M C Stevens
- Sydney Medical School, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales Sydney, Australia; Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre, University of Sydney, Camperdown, Australia.
| | - F M Callaghan
- Sydney Medical School, University of Sydney, Sydney, Australia; Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre, University of Sydney, Camperdown, Australia
| | - P Forrest
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Anaesthetics, Royal Prince Alfred Hospital, Sydney, Australia
| | - P G Bannon
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Anaesthetics, Royal Prince Alfred Hospital, Sydney, Australia; Institute of Academic Surgery, Royal Prince Alfred Hospital, Sydney, Australia; The Baird Institute, Sydney, Australia
| | - S M Grieve
- Sydney Medical School, University of Sydney, Sydney, Australia; Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre, University of Sydney, Camperdown, Australia; Department of Radiology, Royal Prince Alfred Hospital, Sydney, Australia
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32
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33
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Biglino G, Capelli C, Bruse J, Bosi GM, Taylor AM, Schievano S. Computational modelling for congenital heart disease: how far are we from clinical translation? Heart 2016; 103:98-103. [PMID: 27798056 PMCID: PMC5284484 DOI: 10.1136/heartjnl-2016-310423] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/26/2016] [Accepted: 09/29/2016] [Indexed: 12/17/2022] Open
Abstract
Computational models of congenital heart disease (CHD) have become increasingly sophisticated over the last 20 years. They can provide an insight into complex flow phenomena, allow for testing devices into patient-specific anatomies (pre-CHD or post-CHD repair) and generate predictive data. This has been applied to different CHD scenarios, including patients with single ventricle, tetralogy of Fallot, aortic coarctation and transposition of the great arteries. Patient-specific simulations have been shown to be informative for preprocedural planning in complex cases, allowing for virtual stent deployment. Novel techniques such as statistical shape modelling can further aid in the morphological assessment of CHD, risk stratification of patients and possible identification of new ‘shape biomarkers’. Cardiovascular statistical shape models can provide valuable insights into phenomena such as ventricular growth in tetralogy of Fallot, or morphological aortic arch differences in repaired coarctation. In a constant move towards more realistic simulations, models can also account for multiscale phenomena (eg, thrombus formation) and importantly include measures of uncertainty (ie, CIs around simulation results). While their potential to aid understanding of CHD, surgical/procedural decision-making and personalisation of treatments is undeniable, important elements are still lacking prior to clinical translation of computational models in the field of CHD, that is, large validation studies, cost-effectiveness evaluation and establishing possible improvements in patient outcomes.
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Affiliation(s)
- Giovanni Biglino
- Bristol Heart Institute, School of Clinical Sciences, University of Bristol, Bristol, UK.,Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Claudio Capelli
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Jan Bruse
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Giorgia M Bosi
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Andrew M Taylor
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Silvia Schievano
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
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