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Choi RS, DiNardo JA, Brown ML. Superior Cavopulmonary Connection: Its Physiology, Limitations, and Anesthetic Implications. Semin Cardiothorac Vasc Anesth 2020; 24:337-348. [PMID: 32646291 DOI: 10.1177/1089253220939361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The superior cavopulmonary connection (SCPC) or "bidirectional Glenn" is an integral, intermediate stage in palliation of single ventricle patients to the Fontan procedure. The procedure, normally performed at 3 to 6 months of life, increases effective pulmonary blood flow and reduces the ventricular volume load in patients with single ventricle (parallel circulation) physiology. While the SCPC, with or without additional sources of pulmonary blood flow, cannot be considered a long-term palliation strategy, there are a subset of patients who require SCPC palliation for a longer interval than the typical patient. In this article, we will review the physiology of SCPC, the consequences of prolonged SCPC palliation, and modes of failure. We will also discuss strategies to augment pulmonary blood flow in the presence of an SCPC. The anesthetic considerations in SCPC patients will also be discussed, as these patients may present for noncardiac surgery from infancy to adulthood.
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Affiliation(s)
- Ray S Choi
- Children's Hospital Colorado, Denver, CO, USA.,Boston Children's Hospital, Boston, MA, USA
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2
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Gallagher MB, Aycock KI, Craven BA, Manning KB. Steady Flow in a Patient-Averaged Inferior Vena Cava-Part I: Particle Image Velocimetry Measurements at Rest and Exercise Conditions. Cardiovasc Eng Technol 2018; 9:641-653. [PMID: 30411228 PMCID: PMC10508872 DOI: 10.1007/s13239-018-00390-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 10/19/2018] [Indexed: 12/23/2022]
Abstract
PURPOSE Although many previous computational fluid dynamics (CFD) studies have investigated the hemodynamics in the inferior vena cava (IVC), few studies have compared computational predictions to experimental data, and only qualitative comparisons have been made. Herein, we provide particle image velocimetry (PIV) measurements of flow in a patient-averaged IVC geometry under idealized conditions typical of those used in the preclinical evaluation of IVC filters. METHODS Measurements are acquired under rest and exercise flow rate conditions in an optically transparent model fabricated using 3D printing. To ensure that boundary conditions are well-defined and to make follow-on CFD validation studies more convenient, fully-developed flow is provided at the inlets (i.e., the iliac veins) by extending them with straight rigid tubing longer than the estimated entrance lengths. Velocity measurements are then obtained at the downstream end of the tubing to confirm Poiseuille inflow boundary conditions. RESULTS Measurements in the infrarenal IVC reveal that flow profiles are blunter in the sagittal plane (minor axis) than in the coronal plane (major axis). Peak in-plane velocity magnitudes are 4.9 cm/s and 27 cm/s under the rest and exercise conditions, respectively. Flow profiles are less parabolic and exhibit more inflection points at the higher flow rate. Bimodal velocity peaks are also observed in the sagittal plane at the elevated flow condition. CONCLUSIONS The IVC geometry, boundary conditions, and infrarenal velocity measurements are provided for download on a free and publicly accessible repository at https://doi.org/10.6084/m9.figshare.7198703 . These data will facilitate future CFD validation studies of idealized, in vitro IVC hemodynamics and of similar laminar flows in vascular geometries.
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Affiliation(s)
- Maureen B Gallagher
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, USA
| | - Kenneth I Aycock
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Brent A Craven
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Keefe B Manning
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, USA.
- Department of Surgery, Penn State Hershey Medical Center, Hershey, PA, USA.
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Ni MW, Prather RO, Rodriguez G, Quinn R, Divo E, Fogel M, Kassab AJ, DeCampli WM. Computational Investigation of a Self-Powered Fontan Circulation. Cardiovasc Eng Technol 2018; 9:202-216. [PMID: 29464511 DOI: 10.1007/s13239-018-0342-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 02/12/2018] [Indexed: 11/25/2022]
Abstract
Children born with anatomic or functional "single ventricle" must progress through two or more major operations to sustain life. This management sequence culminates in the total cavopulmonary connection, or "Fontan" operation. A consequence of the "Fontan circulation", however, is elevated central venous pressure and inadequate ventricular preload, which contribute to continued morbidity. We propose a solution to these problems by increasing pulmonary blood flow using an "injection jet" (IJS) in which the source of blood flow and energy is the ventricle itself. The IJS has the unique property of lowering venous pressure while enhancing pulmonary blood flow and ventricular preload. We report preliminary results of an analysis of this circulation using a tightly-coupled, multi-scale computational fluid dynamics model. Our calculations show that, constraining the excess volume load to the ventricle at 50% (pulmonary to systemic flow ratio of 1.5), an optimally configured IJS can lower venous pressure by 3 mmHg while increasing systemic oxygen delivery. Even this small decrease in venous pressure may have substantial clinical impact on the Fontan patient. These findings support the potential for a straightforward surgical modification to decrease venous pressure, and perhaps improve clinical outcome in selected patients.
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Affiliation(s)
- Marcus W Ni
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816, USA.
| | - Ray O Prather
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816, USA
| | - Giovanna Rodriguez
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816, USA
| | - Rachel Quinn
- College of Medicine, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, USA
| | - Eduardo Divo
- Department of Mechanical Engineering, Embry-Riddle Aeronautical University, 600 S Clyde Morris Blvd, Daytona Beach, FL, USA
| | - Mark Fogel
- The Perelman School of Medicine at The University of Pennsylvania, Philadelphia, PA, USA.,Division of Cardiology/Department of Pediatrics and the Department of Radiology, The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, USA
| | - Alain J Kassab
- Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816, USA
| | - William M DeCampli
- College of Medicine, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, USA.,Arnold Palmer Hospital for Children, 92 W Miller St, Orlando, FL, USA
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Jarvis K, Schnell S, Barker AJ, Garcia J, Lorenz R, Rose M, Chowdhary V, Carr J, Robinson JD, Rigsby CK, Markl M. Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI. Pediatr Radiol 2016; 46:1507-19. [PMID: 27350377 PMCID: PMC5039076 DOI: 10.1007/s00247-016-3654-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/04/2016] [Accepted: 06/02/2016] [Indexed: 11/26/2022]
Abstract
BACKGROUND Asymmetrical caval to pulmonary blood flow is suspected to cause complications in patients with Fontan circulation. The aim of this study was to test the feasibility of 4-D flow MRI for characterizing the relationship between 3-D blood flow distribution and vascular geometry. OBJECTIVE We hypothesized that both flow distribution and geometry can be calculated with low interobserver variability and will detect a direct relationship between flow distribution and Fontan geometry. MATERIALS AND METHODS Four-dimensional flow MRI was acquired in 10 Fontan patients (age: 16 ± 4 years [mean ± standard deviation], range: 9-21 years). The Fontan connection was isolated by 3-D segmentation to evaluate flow distribution from the inferior vena cava (IVC) and superior vena cava (SVC) to the left and right pulmonary arteries (LPA, RPA) and to characterize geometry (cross-sectional area, caval offset, vessel angle). RESULTS Flow distribution results indicated SVC flow tended toward the RPA while IVC flow was more evenly distributed (SVC to RPA: 78% ± 28 [9-100], IVC to LPA: 54% ± 28 [4-98]). There was a significant relationship between pulmonary artery cross-sectional area and flow distribution (IVC to RPA: R(2)=0.50, P=0.02; SVC to LPA: R(2)=0.81, P=0.0004). Good agreement was found between observers and for flow distribution when compared to net flow values. CONCLUSION Four-dimensional flow MRI was able to detect relationships between flow distribution and vessel geometry. Future studies are warranted to investigate the potential of patient specific hemodynamic analysis to improve diagnostic capability.
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Affiliation(s)
- Kelly Jarvis
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA.
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, USA.
| | - Susanne Schnell
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
| | - Alex J Barker
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
| | - Julio Garcia
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
| | - Ramona Lorenz
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
| | - Michael Rose
- Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Varun Chowdhary
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
| | - James Carr
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
| | - Joshua D Robinson
- Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Division of Cardiology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Cynthia K Rigsby
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
- Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Michael Markl
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave., Suite 1600, Chicago, IL, 60611, USA
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, USA
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Computational modeling of Fontan physiology: at the crossroads of pediatric cardiology and biomedical engineering. Int J Cardiovasc Imaging 2014; 30:1073-84. [DOI: 10.1007/s10554-014-0442-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/29/2014] [Indexed: 02/05/2023]
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Use of computational fluid dynamics to estimate hemodynamic effects of respiration on hypoplastic left heart syndrome surgery: total cavopulmonary connection treatments. ScientificWorldJournal 2013; 2013:131597. [PMID: 24385870 PMCID: PMC3872434 DOI: 10.1155/2013/131597] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 11/06/2013] [Indexed: 11/27/2022] Open
Abstract
Total cavopulmonary connection (TCPC), a typical kind of Fontan procedure, is commonly used in the treatment of a functional single ventricle. The palliative cardiothoracic procedure is performed by connecting the superior vena cava and the inferior vena cava to the pulmonary arteries. Due to the difficulty of direct study in vivo, in this paper, computational fluid dynamics (CFD) was introduced to estimate the outcomes of patient-specific TCPC configuration. We mainly focused on the influence of blood pulsation and respiration. Fast Fourier transforms method was employed to separate the measured flow conditions into the rate of breath and heart beat. Blood flow performance around the TCPC connection was investigated by analyzing the results of time-varying energy losses, blood flow distribution rate, local pressure, and wall shear stress distributions. It was found that the value of energy loss including the influence of respiration was 1.5 times higher than the value of energy loss disregarding respiratory influences. The results indicated that the hemodynamic outcomes of TCPC treatment are obviously influenced by respiration. The influence of respiration plays an important role in estimating the results of TCPC treatment and thus should be included as one of the important conditions of computational haemodynamic analysis.
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Ding J, Liu Y, Wang F. Influence of bypass angles on extracardiac Fontan connections: a numerical study. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:351-362. [PMID: 23345174 DOI: 10.1002/cnm.2508] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Revised: 05/02/2012] [Accepted: 06/07/2012] [Indexed: 06/01/2023]
Abstract
The extracardiac Fontan connection (EFC) is an effective treatment for congenital single ventricle heart defects. Numerous studies have sought to optimize the EFC design. However, the optimal design of EFC remains uncertain. This study aims to examine the influence of bypass angles between the inferior vena cava (IVC) and right pulmonary artery (RPA), and the angles between the IVC and superior vena cava (SVC), on hemodynamics. Furthermore, this study demonstrates a methodology for cardiovascular surgical planning. First, a three-dimensional anatomical geometry was reconstructed from the medical images of a patient with single ventricle heart defects. Second, based on haptic deformations, six computational models were virtually generated. Third, numerical simulations were conducted using computational fluid dynamics through the finite volume method. Finally, hemodynamic parameters were obtained and evaluated. The hemodynamic parameters, including the flow patterns, streamlines, and swirling flow, were obtained. Meanwhile, the energy loss and flow distributions of vena cava blood were calculated. First, the hepatic artery blood distribution to two lungs and the flow ratio of the left pulmonary artery to RPA are sensitive to the angle between the IVC and RPA and not to that between the IVC and SVC. Second, energy dissipation is mainly sensitive to the angle between the IVC and SVC and not to that between the IVC and RPA. Third, an appropriate increase in the angle between the IVC and RPA or that between the IVC and SVC may lead to optimal options. This study is useful for surgeons in evaluating optimal Fontan options.
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Affiliation(s)
- Jinli Ding
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, P. R., China
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Chopski SG, Downs E, Haggerty CM, Yoganathan AP, Throckmorton AL. Laser Flow Measurements in an Idealized Total Cavopulmonary Connection With Mechanical Circulatory Assistance. Artif Organs 2011; 35:1052-64. [DOI: 10.1111/j.1525-1594.2011.01345.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Sankaran S, Marsden AL. A stochastic collocation method for uncertainty quantification and propagation in cardiovascular simulations. J Biomech Eng 2011; 133:031001. [PMID: 21303177 DOI: 10.1115/1.4003259] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Simulations of blood flow in both healthy and diseased vascular models can be used to compute a range of hemodynamic parameters including velocities, time varying wall shear stress, pressure drops, and energy losses. The confidence in the data output from cardiovascular simulations depends directly on our level of certainty in simulation input parameters. In this work, we develop a general set of tools to evaluate the sensitivity of output parameters to input uncertainties in cardiovascular simulations. Uncertainties can arise from boundary conditions, geometrical parameters, or clinical data. These uncertainties result in a range of possible outputs which are quantified using probability density functions (PDFs). The objective is to systemically model the input uncertainties and quantify the confidence in the output of hemodynamic simulations. Input uncertainties are quantified and mapped to the stochastic space using the stochastic collocation technique. We develop an adaptive collocation algorithm for Gauss-Lobatto-Chebyshev grid points that significantly reduces computational cost. This analysis is performed on two idealized problems--an abdominal aortic aneurysm and a carotid artery bifurcation, and one patient specific problem--a Fontan procedure for congenital heart defects. In each case, relevant hemodynamic features are extracted and their uncertainty is quantified. Uncertainty quantification of the hemodynamic simulations is done using (a) stochastic space representations, (b) PDFs, and (c) the confidence intervals for a specified level of confidence in each problem.
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10
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Vignon-Clementel IE, Marsden AL, Feinstein JA. A primer on computational simulation in congenital heart disease for the clinician. PROGRESS IN PEDIATRIC CARDIOLOGY 2010. [DOI: 10.1016/j.ppedcard.2010.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Marsden AL, Bernstein AJ, Reddy VM, Shadden SC, Spilker RL, Chan FP, Taylor CA, Feinstein JA. Evaluation of a novel Y-shaped extracardiac Fontan baffle using computational fluid dynamics. J Thorac Cardiovasc Surg 2009; 137:394-403.e2. [PMID: 19185159 DOI: 10.1016/j.jtcvs.2008.06.043] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 04/01/2008] [Accepted: 06/15/2008] [Indexed: 11/18/2022]
Abstract
OBJECTIVES The objective of this work is to evaluate the hemodynamic performance of a new Y-graft modification of the extracardiac conduit Fontan operation. The performance of the Y-graft design is compared to two designs used in current practice: a t-junction connection of the venae cavae and an offset between the inferior and superior venae cavae. METHODS The proposed design replaces the current tube grafts used to connect the inferior vena cava to the pulmonary arteries with a Y-shaped graft. Y-graft hemodynamics were evaluated at rest and during exercise with a patient-specific model from magnetic resonance imaging data together with computational fluid dynamics. Four clinically motivated performance measures were examined: Fontan pressures, energy efficiency, inferior vena cava flow distribution, and wall shear stress. Two variants of the Y-graft were evaluated: an "off-the-shelf" graft with 9-mm branches and an "area-preserving" graft with 12-mm branches. RESULTS Energy efficiency of the 12-mm Y-graft was higher than all other models at rest and during exercise, and the reduction in efficiency from rest to exercise was improved by 38%. Both Y-graft designs reduced superior vena cava pressures during exercise by as much as 5 mm Hg. The Y-graft more equally distributed the inferior vena cava flow to both lungs, whereas the offset design skewed 70% of the flow to the left lung. The 12-mm graft resulted in slightly larger regions of low wall shear stress than other models; however, minimum shear stress values were similar. CONCLUSIONS The area-preserving 12-mm Y-graft is a promising modification of the Fontan procedure that should be clinically evaluated. Further work is needed to correlate our performance metrics with clinical outcomes, including exercise intolerance, incidence of protein-losing enteropathy, and thrombus formation.
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Affiliation(s)
- Alison L Marsden
- Mechanical and Aerospace Engineering Department, University of California, San Diego, Calif, USA
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12
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Pekkan K, Whited B, Kanter K, Sharma S, de Zelicourt D, Sundareswaran K, Frakes D, Rossignac J, Yoganathan AP. Patient-specific surgical planning and hemodynamic computational fluid dynamics optimization through free-form haptic anatomy editing tool (SURGEM). Med Biol Eng Comput 2008; 46:1139-52. [DOI: 10.1007/s11517-008-0377-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Accepted: 07/13/2008] [Indexed: 11/30/2022]
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13
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Kitajima HD, Sundareswaran KS, Teisseyre TZ, Astary GW, Parks WJ, Skrinjar O, Oshinski JN, Yoganathan AP. Comparison of Particle Image Velocimetry and Phase Contrast MRI in a Patient-Specific Extracardiac Total Cavopulmonary Connection. J Biomech Eng 2008; 130:041004. [DOI: 10.1115/1.2900725] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Particle image velocimetry (PIV) and phase contrast magnetic resonance imaging (PC-MRI) have not been compared in complex biofluid environments. Such analysis is particularly useful to investigate flow structures in the correction of single ventricle congenital heart defects, where fluid dynamic efficiency is essential. A stereolithographic replica of an extracardiac total cavopulmonary connection (TCPC) is studied using PIV and PC-MRI in a steady flow loop. Volumetric two-component PIV is compared to volumetric three-component PC-MRI at various flow conditions. Similar flow structures are observed in both PIV and PC-MRI, where smooth flow dominates the extracardiac TCPC, and superior vena cava flow is preferential to the right pulmonary artery, while inferior vena cava flow is preferential to the left pulmonary artery. Where three-component velocity is available in PC-MRI studies, some helical flow in the extracardiac TCPC is observed. Vessel cross sections provide an effective means of validation for both experiments, and velocity magnitudes are of the same order. The results highlight similarities to validate flow in a complex patient-specific extracardiac TCPC. Additional information obtained by velocity in three components further describes the complexity of the flow in anatomic structures.
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Affiliation(s)
- Hiroumi D. Kitajima
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, U. A. Whitaker Building, 313 Ferst Drive, Atlanta, GA 30332-0535
| | - Kartik S. Sundareswaran
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, U. A. Whitaker Building, 313 Ferst Drive, Atlanta, GA 30332-0535
| | - Thomas Z. Teisseyre
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, U. A. Whitaker Building, 313 Ferst Drive, Atlanta, GA 30332-0535
| | - Garrett W. Astary
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, U. A. Whitaker Building, 313 Ferst Drive, Atlanta, GA 30332-0535
| | - W. James Parks
- Children’s Healthcare of Atlanta, Emory University School of Medicine, 1440 Clifton Road North East, Atlanta, GA 30322
| | - Oskar Skrinjar
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0535
| | - John N. Oshinski
- Emory University School of Medicine, 1440 Clifton Road North East, Atlanta, GA 30322
| | - Ajit P. Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, U. A. Whitaker Building, 313 Ferst Drive, Atlanta, GA 30332-0535; Emory University School of Medicine, 1440 Clifton Road North East, Atlanta, GA 30322
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Modeling the Fontan circulation: where we are and where we need to go. Pediatr Cardiol 2008; 29:3-12. [PMID: 17917765 DOI: 10.1007/s00246-007-9104-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2007] [Revised: 06/30/2007] [Accepted: 07/03/2007] [Indexed: 10/22/2022]
Abstract
The Fontan procedure and its subsequent modifications over the past 30 years can be described as a class of surgical procedures for patients born with complex congenital heart disease exhibiting a single-ventricle physiology. The long-term outcome for children currently undergoing a Fontan procedure remains worrisome because of multiple late morbidities observed. Despite significant modeling efforts spanning three decades, improvements to the Fontan procedure have occurred without comprehensive validation from these modeling studies. Careful examination shows that modeling studies to date offer only a "glimpse through a keyhole" into understanding and modeling a representative range of the variations in anatomy and physiology that exist in Fontan patients. Suggestions for future investigations are provided.
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Bove EL, de Leval MR, Migliavacca F, Balossino R, Dubini G. Toward optimal hemodynamics: computer modeling of the Fontan circuit. Pediatr Cardiol 2007; 28:477-81. [PMID: 17763891 DOI: 10.1007/s00246-007-9009-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The construction of efficient designs with minimal energy losses is especially important for cavopulmonary connections. The science of computational fluid dynamics has been increasingly used to study the hemodynamic performance of surgical operations. Three-dimensional computer models can be accurately constructed of typical cavopulmonary connections used in clinical practice based on anatomic data derived from magnetic resonance scans, angiocardiograms, and echocardiograms. Using these methods, the hydraulic performance of the hemi-Fontan, bidirectional Glenn, and a variety of types of completion Fontan operations can be evaluated and compared. This methodology has resulted in improved understanding and design of these surgical operations.
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Affiliation(s)
- E L Bove
- Department of Surgery, Section of Cardiac Surgery, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA.
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16
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Marsden AL, Vignon-Clementel IE, Chan FP, Feinstein JA, Taylor CA. Effects of Exercise and Respiration on Hemodynamic Efficiency in CFD Simulations of the Total Cavopulmonary Connection. Ann Biomed Eng 2006; 35:250-63. [PMID: 17171509 DOI: 10.1007/s10439-006-9224-3] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Accepted: 10/23/2006] [Indexed: 10/23/2022]
Abstract
Congenital heart defects with a single functional ventricle, such as hypoplastic left heart syndrome and tricuspid atresia, require a staged surgical approach to separate the systemic and pulmonary circulations. Ultimately, the venous or pulmonary side of the heart is bypassed by directly connecting the vena cava to the pulmonary arteries with a modified t-shaped junction. The Fontan procedure (total cavopulmonary connection, TCPC) completes this process of separation. To date, computational fluid dynamics (CFD) simulations in this low pressure, passive flow, intrathoracic system have neglected the presumed important effects of respiration on physiology and higher "stress" states such as with exercise have never been considered. We hypothesize that incorporating effects of respiration and exercise would provide more realistic estimates of TCPC performance. Time-dependent, 3D blood flow simulations are performed by a custom finite element solver for two patient-specific Fontan models with a novel respiration model, developed to generate physiologic time-varying flow conditions. Blood flow features, pressure, and energy efficiency are analyzed at rest and with increasing flow rates to simulate exercise conditions. The simulations produce realistic pressure and flow data, comparable to that measured by catheterization and echocardiography, and demonstrate substantial increases in energy dissipation (i.e. decreased performance) with exercise and respiration due to increasing intensity of small scale vortices in the flow. As would be expected, these changes are highly dependent on patient-specific anatomy and Fontan geometry. We propose that respiration and exercise should be incorporated into TCPC CFD simulations to provide increasingly realistic evaluations of TCPC performance.
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Affiliation(s)
- Alison L Marsden
- Pediatrics Department, Stanford University, Clark Center E350, Stanford, CA 94305, USA.
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Venkatachari AK, Halliburton SS, Setser RM, White RD, Chatzimavroudis GP. Noninvasive quantification of fluid mechanical energy losses in the total cavopulmonary connection with magnetic resonance phase velocity mapping. Magn Reson Imaging 2006; 25:101-9. [PMID: 17222721 DOI: 10.1016/j.mri.2006.09.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Accepted: 09/09/2006] [Indexed: 11/29/2022]
Abstract
A major determinant of the success of surgical vascular modifications, such as the total cavopulmonary connection (TCPC), is the energetic efficiency that is assessed by calculating the mechanical energy loss of blood flow through the new connection. Currently, however, to determine the energy loss, invasive pressure measurements are necessary. Therefore, this study evaluated the feasibility of the viscous dissipation (VD) method, which has the potential to provide the energy loss without the need for invasive pressure measurements. Two experimental phantoms, a U-shaped tube and a glass TCPC, were scanned in a magnetic resonance (MR) imaging scanner and the images were used to construct computational models of both geometries. MR phase velocity mapping (PVM) acquisitions of all three spatial components of the fluid velocity were made in both phantoms and the VD was calculated. VD results from MR PVM experiments were compared with VD results from computational fluid dynamics (CFD) simulations on the image-based computational models. The results showed an overall agreement between MR PVM and CFD. There was a similar ascending tendency in the VD values as the image spatial resolution increased. The most accurate computations of the energy loss were achieved for a CFD grid density that was too high for MR to achieve under current MR system capabilities (in-plane pixel size of less than 0.4 mm). Nevertheless, the agreement between the MR PVM and the CFD VD results under the same resolution settings suggests that the VD method implemented with a clinical imaging modality such as MR has good potential to quantify the energy loss in vascular geometries such as the TCPC.
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Affiliation(s)
- Anand K Venkatachari
- Laboratory of Biofluid Mechanics and Cardiovascular Imaging, Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH 44115-2425, USA
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18
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Orlando W, Shandas R, DeGroff C. Efficiency differences in computational simulations of the total cavo-pulmonary circulation with and without compliant vessel walls. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2006; 81:220-7. [PMID: 16455152 DOI: 10.1016/j.cmpb.2005.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 11/15/2005] [Accepted: 11/23/2005] [Indexed: 05/06/2023]
Abstract
The Fontan operation is a palliative surgical procedure performed on children born with congenital defects of the heart that have yielded only a single functioning ventricle. The total cavo-pulmonary connection (TCPC) is the most popular variant of the Fontan procedure. The objective of the study was to quantify and compare the efficiency of numerical models of the TCPC with rigid versus elastic vessel wall models. The pressure drop and power loss through both type TCPC models was measured. Significant differences in efficiencies exist between rigid versus elastic numerical models. We have shown incorporating elasticity into numerical models of the total cavo-pulmonary connection is important when determining circuit efficiencies.
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Affiliation(s)
- Wendell Orlando
- Northwest Research Associates, Inc., Colorado Research Associates Division, 3380 Mitchell Lane, Boulder, CO 80301, USA
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Frakes D, Smith M, de Zélicourt D, Pekkan K, Yoganathan A. Three-dimensional velocity field reconstruction. J Biomech Eng 2005; 126:727-35. [PMID: 15796331 DOI: 10.1115/1.1824117] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The problem of inter-slice magnetic resonance (MR) image reconstruction is encountered often in medical imaging applications, in such scenarios, there is a need to approximate information not captured in contiguously acquired MR images due to hardware sampling limitations. In the context of velocity field reconstruction, these data are required for visualization and computational analyses of flow fields to be effective. To provide more complete velocity information, a method has been developed for the reconstruction of flow fields based on adaptive control grid interpolation (ACGI). In this study, data for reconstruction were acquired via MRJ from in vitro models of surgically corrected pediatric cardiac vasculatures. Reconstructed velocity fields showed strong qualitative agreement with those obtained via other acquisition techniques. Quantitatively reconstruction was shown to produce data of comparable quality to accepted velocity data acquisition methods. Results indicate that ACGI-based velocity field reconstruction is capable of producing information suitable for a variety of applications demanding three-dimensional in vivo velocity data.
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Affiliation(s)
- David Frakes
- Georgia Institute of Technology, Atlanta, GA 30332, USA
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20
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Migliavacca F, Dubini G. Computational modeling of vascular anastomoses. Biomech Model Mechanobiol 2005; 3:235-50. [PMID: 15772842 DOI: 10.1007/s10237-005-0070-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Accepted: 12/28/2004] [Indexed: 10/25/2022]
Abstract
Recent development of computational technology allows a level of knowledge of biomechanical factors in the healthy or pathological cardiovascular system that was unthinkable a few years ago. In particular, computational fluid dynamics (CFD) and computational structural (CS) analyses have been used to evaluate specific quantities, such as fluid and wall stresses and strains, which are very difficult to measure in vivo. Indeed, CFD and CS offer much more variability and resolution than in vitro and in vivo methods, yet computations must be validated by careful comparison with experimental and clinical data. The enormous parallel development of clinical imaging such as magnetic resonance or computed tomography opens a new way toward a detailed patient-specific description of the actual hemodynamics and structural behavior of living tissues. Coupling of CFD/CS and clinical images is becoming a standard evaluation that is expected to become part of the clinical practice in the diagnosis and in the surgical planning in advanced medical centers. This review focuses on computational studies of fluid and structural dynamics of a number of vascular anastomoses: the coronary bypass graft anastomoses, the arterial peripheral anastomoses, the arterio-venous graft anastomoses and the vascular anastomoses performed in the correction of congenital heart diseases.
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Affiliation(s)
- Francesco Migliavacca
- Bioengineering and Structural Engineering Department, Laboratory of Biological Structure Mechanics, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy.
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21
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Roman KS, Kellenberger CJ, Farooq S, MacGowan CK, Gilday DL, Yoo SJ. Comparative imaging of differential pulmonary blood flow in patients with congenital heart disease: magnetic resonance imaging versus lung perfusion scintigraphy. Pediatr Radiol 2005; 35:295-301. [PMID: 15490145 DOI: 10.1007/s00247-004-1344-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2004] [Revised: 08/12/2004] [Accepted: 08/20/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND Lung perfusion scintigraphy is considered the gold standard to assess differential pulmonary blood flow while magnetic resonance (MR) has been shown to be an accurate alternative in some studies. OBJECTIVE The purpose of the study was to assess the accuracy of phase contrast magnetic resonance (PC-MR) in measuring pulmonary blood flow ratio compared with lung perfusion scintigraphy in patients with complex pulmonary artery anatomy or pulmonary hypertension and to document reasons for discrepant results. MATERIALS AND METHODS We identified 25 cases of congenital heart disease between January 2000 and 2003, in whom both techniques of assessing pulmonary blood flow were performed within a 6-month period without an interim surgical or transcatheter intervention. The study group included cases with branch pulmonary artery stenosis, intracardiac shunts, single ventricle circulation, pulmonary venous anomalies and conotruncal defects. The mean age at study was 5.7 years (range 0.33-12) with a mean weight of 20.3 kg (range 6.5-53.6). The two methods were compared using a Bland-Altman analysis, and the Pearson correlation coefficient was calculated using the lung scan as the gold standard. Discrepant results were examined by reviewing the source images to elucidate reasons for error by MR. RESULTS Bland-Altman analysis comparing right pulmonary artery (RPA) blood flow percentage, as measured by each modality, showed a mean difference of 1.43+/-9.8 (95% limits of agreement: -17.8, 20.6) with a correlation coefficient of r=0.84, P<0.0001. In six (24%) cases a large difference (>10%) was found with a mean difference between techniques of 17.9%. The reasons for discrepant results included MR artifacts, dephasing owing to turbulent flow, site of data acquisition and lobar lung collapse. CONCLUSION When using PC-MR to assess pulmonary blood flow ratio, important technical errors occur in a significant proportion of patients who have abnormal pulmonary artery anatomy or pulmonary hypertension. If these technical errors are avoided, PC-MR is able to supply both anatomic and quantitative functional information in this patient population.
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Affiliation(s)
- Kevin S Roman
- Department of Cardiology, Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
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22
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DeGroff C, Birnbaum B, Shandas R, Orlando W, Hertzberg J. Computational simulations of the total cavo-pulmonary connection: insights in optimizing numerical solutions. Med Eng Phys 2005; 27:135-46. [PMID: 15642509 DOI: 10.1016/j.medengphy.2004.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Revised: 09/23/2004] [Accepted: 09/30/2004] [Indexed: 11/25/2022]
Abstract
The Fontan procedure is a palliative surgical technique that is used to treat patients with congenital heart defects that include complex lesions such as those with a hypoplastic ventricle. In vitro, in vivo, and computational models of a set of modifications to the Fontan procedure, called the total cavopulmonary connection (TCPC), have been developed. Using these modeling methods, attempts have been made at finding the most energy efficient TCPC circuit. Computational modeling has distinct advantages to other modeling methods. However, discrepancies have been found in validation studies of TCPC computational models. There is little in the literature available to help explain and correct for such discrepancies. Differences in computational results can occur when choosing between steady flow versus transient flow numerical solvers. In this study transient flow solver results were shown to be more consistent with results from previous TCPC in vitro experiments. Using a transient flow solver we found complex fluctuating flow patterns can exist with steady inflow boundary conditions in computational models of the TCPC. To date such findings have not been reported in the literature. Furthermore, our computational modeling results suggest fluctuating flow patterns as well as the magnitudes of these secondary flow structures diminish if the TCPC offset between vena cavae is increased or if flanged connections are added. An association was found between these modifications and improvements in TCPC circuit flow efficiencies. In summary, development of accurate computational simulations in the validation process is critical to efforts in finding the most efficient TCPC circuits, efforts aimed at potentially improving the long term outcome for Fontan patients.
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Affiliation(s)
- Curt DeGroff
- Cardiovascular Flow Research Laboratory, The Children's Hospital, Denver/University of Colorado Health Sciences Center, Denver, 1056 E. 19th Avenue, B-100 Denver, CO 80218, USA.
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Pekkan K, de Zélicourt D, Ge L, Sotiropoulos F, Frakes D, Fogel MA, Yoganathan AP. Physics-Driven CFD Modeling of Complex Anatomical Cardiovascular Flows?A TCPC Case Study. Ann Biomed Eng 2005; 33:284-300. [PMID: 15868719 DOI: 10.1007/s10439-005-1731-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent developments in medical image acquisition combined with the latest advancements in numerical methods for solving the Navier-Stokes equations have created unprecedented opportunities for developing simple and reliable computational fluid dynamics (CFD) tools for meeting patient-specific surgical planning objectives. However, for CFD to reach its full potential and gain the trust and confidence of medical practitioners, physics-driven numerical modeling is required. This study reports on the experience gained from an ongoing integrated CFD modeling effort aimed at developing an advanced numerical simulation tool capable of accurately predicting flow characteristics in an anatomically correct total cavopulmonary connection (TCPC). An anatomical intra-atrial TCPC model is reconstructed from a stack of magnetic resonance (MR) images acquired in vivo. An exact replica of the computational geometry was built using transparent rapid prototyping. Following the same approach as in earlier studies on idealized models, flow structures, pressure drops, and energy losses were assessed both numerically and experimentally, then compared. Numerical studies were performed with both a first-order accurate commercial software and a recently developed, second-order accurate, in-house flow solver. The commercial CFD model could, with reasonable accuracy, capture global flow quantities of interest such as control volume power losses and pressure drops and time-averaged flow patterns. However, for steady inflow conditions, both flow visualization experiments and particle image velocimetry (PIV) measurements revealed unsteady, complex, and highly 3D flow structures, which could not be captured by this numerical model with the available computational resources and additional modeling efforts that are described. Preliminary time-accurate computations with the in-house flow solver were shown to capture for the first time these complex flow features and yielded solutions in good agreement with the experimental observations. Flow fields obtained were similar for the studied total cardiac output range (1-3 1/min); however hydrodynamic power loss increased dramatically with increasing cardiac output, suggesting significant energy demand at exercise conditions. The simulation of cardiovascular flows poses a formidable challenge to even the most advanced CFD tools currently available. A successful prediction requires a two-pronged, physics-based approach, which integrates high-resolution CFD tools and high-resolution laboratory measurements.
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Affiliation(s)
- Kerem Pekkan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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24
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Liu Y, Pekkan K, Jones SC, Yoganathan AP. The Effects of Different Mesh Generation Methods on Computational Fluid Dynamic Analysis and Power Loss Assessment in Total Cavopulmonary Connection. J Biomech Eng 2004; 126:594-603. [PMID: 15648812 DOI: 10.1115/1.1800553] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The flow field and energetic efficiency of total cavopulmonary connection (TCPC) models have been studied by both in vitro experiment and computational fluid dynamics (CFD). All the previous CFD studies have employed the structured mesh generation method to create the TCPC simulation model. In this study, a realistic TCPC model with complete anatomical features was numerically simulated using both structured and unstructured mesh generation methods. The flow fields and energy losses were compared in these two meshes. Two different energy loss calculation methods, the control volume and viscous dissipation methods, were investigated. The energy losses were also compared to the in vitro experimental results. The results demonstrated that: (1) the flow fields in the structured model were qualitatively similar to the unstructured model; (2) more vortices were present in the structured model than in the unstructured model; (3) both models had the least energy loss when flow was equally distributed to the left and right pulmonary arteries, while high losses occurred for extreme pulmonary arterial flow splits; (4) the energy loss results calculated using the same method were significantly different for different meshes; and (5) the energy loss results calculated using different methods were significantly different for the same mesh.
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Affiliation(s)
- Yutong Liu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
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Migliavacca F, Dubini G, Bove EL, de Leval MR. Computational fluid dynamics simulations in realistic 3-D geometries of the total cavopulmonary anastomosis: the influence of the inferior caval anastomosis. J Biomech Eng 2004; 125:805-13. [PMID: 14986405 DOI: 10.1115/1.1632523] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fluid dynamics of Total Cavo-Pulmonary Connection (TCPC) were studied in 3-D models based on real dimensions obtained by Magnetic Resonance (MR) images. Models differ in terms of shape (intra- or extra-cardiac conduit) and cross section (with or without patch enlargement) of the inferior caval (IVC) anastomosis connection. Realistic pulsatile flows were submitted to both the venae cavae, while porous portions were added at the end of the pulmonary arteries to reproduce the pulmonary afterload. The dissipated power and the flow distribution into the lungs were calculated at different values of pulmonary arteriolar resistances (PAR). The most important results are: i) power dissipation in different TCPC designs is influenced by the actual cross sectional area of the IVC anastomosis and ii) the inclusion of a patch minimizes the dissipated power (range 4-13 mW vs. 14-56 mW). Results also show that the perfusion of the right lung is between 15% and 30% of the whole IVC blood flow when the PAR are evenly distributed between the right and the left lung.
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Affiliation(s)
- Francesco Migliavacca
- Laboratory of Biological Structure Mechanics, Dept. of Bioengineering and Dept. of Structural Engineering, Politecnico di Milano, Milano, Italy.
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26
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Hsia TY, Migliavacca F, Pittaccio S, Radaelli A, Dubini G, Pennati G, de Leval M. Computational fluid dynamic study of flow optimization in realistic models of the total cavopulmonary connections. J Surg Res 2004; 116:305-13. [PMID: 15013370 DOI: 10.1016/j.jss.2003.08.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2003] [Indexed: 12/01/2022]
Abstract
OBJECTIVES AND BACKGROUND In the Fontan circulation, pulmonary and systemic vascular resistances are in series. The influence of various inferior vena cava to pulmonary artery connections in this unique circulatory arrangement was evaluated using computation fluid dynamics methods. METHODS Realistic three-dimensional models of total cavopulmonary connections were created from angiographic measurements to include the hepatic vein, superior vena cava, and branches of the pulmonary arteries. Steady-state finite volume analyses were performed using identical in vivo boundary conditions. Computational solutions calculated the percent hydraulic power dissipation and left-to-right pulmonary arterial flow distribution. RESULTS Simulations of the lateral tunnel, intra-atrial tube, extracardiac conduit with left and right pulmonary artery anastomosis demonstrated extracardiac conduit with left pulmonary artery anastomosis having the lowest energy loss. Varying the extracardiac conduit from 10 to 30 mm resulted in the least energy dissipation at 20 mm. Serial dilation of the lateral tunnel pathway showed a small incremental worsening of energy loss. CONCLUSIONS Maximizing energy conservation in a low-energy flow domain, such as the Fontan circulation, can be significant to its fluid dynamic performance. Although computational modeling cannot predict postoperative failure or functional outcome, this study confirms the importance of local geometry of the surgically created pathway in the total cavopulmonary connection.
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Affiliation(s)
- Tain-Yen Hsia
- Bioengineering and Structural Engineering Department, Politecnico di Milano, Milan, Italy.
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27
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Bove EL, de Leval MR, Migliavacca F, Guadagni G, Dubini G. Computational fluid dynamics in the evaluation of hemodynamic performance of cavopulmonary connections after the Norwood procedure for hypoplastic left heart syndrome. J Thorac Cardiovasc Surg 2003; 126:1040-7. [PMID: 14566244 DOI: 10.1016/s0022-5223(03)00698-6] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Computational fluid dynamics have been used to study the hemodynamic performance of surgical operations, resulting in improved design. Efficient designs with minimal energy losses are especially important for cavopulmonary connections. The purpose of this study was to compare hydraulic performance between the hemi-Fontan and bidirectional Glenn procedures, as well as the various types of completion Fontan operations. METHODS Three-dimensional models were constructed of typical hemi-Fontan and bidirectional Glenn operations according to anatomic data derived from magnetic resonance scans, angiocardiograms, and echocardiograms. Boundary conditions were imposed, and fluid dynamics were calculated from a mathematic code. Power losses, flow distribution to each lung, and pressures were measured at three predetermined levels of pulmonary arteriolar resistance. Models of the lateral tunnel, total cavopulmonary connection, and extracardiac conduit completion Fontan operations were constructed, and power losses, total flow distribution, vena caval and pulmonary arterial pressures, and flow distribution of inferior vena caval return were calculated. RESULTS The hemi-Fontan and bidirectional Glenn procedures performed nearly identically, with similar power losses and nearly equal flow distributions to each lung at all levels of pulmonary arteriolar resistance. However, the lateral tunnel Fontan procedure as performed after the hemi-Fontan operation had lower power losses (6.9 mW, pulmonary arteriolar resistance 3 units) than the total cavopulmonary connection (40.5 mW) or the extracardiac conduit (42.9 mW), although the inclusion of an enlargement patch toward the right in the total cavopulmonary connection was effective in reducing the difference (10.0 mW). Inferior vena caval flow to the right lung was 52% for the lateral tunnel, compared with 19%, 30%, 19%, and 15% for the total cavopulmonary connection, total cavopulmonary connection with right-sided enlargement patch, extracardiac conduit, and extracardiac conduit with a bevel to the left lung, respectively. CONCLUSIONS According to these methods, the hemi-Fontan and bidirectional Glenn procedures performed equally well, but important differences in energy losses and flow distribution were found after the completion Fontan procedures. The superior hydraulic performance of the lateral tunnel Fontan operation after the hemi-Fontan procedure relative to any other method may be due to closer to optimal caval offset achieved in the surgical reconstruction.
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Affiliation(s)
- Edward L Bove
- Section of Cardiac Surgery, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, Mich, USA
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28
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Healy TM, Lucas C, Yoganathan AP. Noninvasive fluid dynamic power loss assessments for total cavopulmonary connections using the viscous dissipation function: a feasibility study. J Biomech Eng 2001; 123:317-24. [PMID: 11563756 DOI: 10.1115/1.1384875] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The total cavopulmonary connection (TCPC) has shown great promise as an effective palliation for single-ventricle congenital heart defects. However, because the procedure results in complete bypass of the right-heart, fluid dynamic power losses may play a vital role in postoperative patient success. Past research has focused on determining power losses using control volume methods. Such methods are not directly applicable clinically without highly invasive pressure measurements. This work proposes the use of the viscous dissipation function as a tool for velocity gradient based estimation of fluid dynamic power loss. To validate this technique, numerical simulations were conducted in a model of the TCPC incorporating a 13.34 mm (one caval diameter) caval offset and a steady cardiac output of 2 L x min(-1). Inlet flow through the superior vena cava was 40 percent of the cardiac output, while outflow through the right pulmonary artery (RPA) was varied between 30 and 70 percent, simulating different blood flow distributions to the lungs. Power losses were determined using control volume and dissipation function techniques applied to the numerical data. Differences between losses computed using these techniques ranged between 3.2 and 9.9 percent over the range of RPA outflows studied. These losses were also compared with experimental measurements front a previous study. Computed power losses slightly exceeded experimental results due to different inlet flow conditions. Although additional experimental study is necessary to establish the clinical applicability of the dissipation function, it is believed that this method, in conjunction with velocity gradient information derived from imaging modalities such as magnetic resonance imaging, can provide a noninvasive means of assessing power losses within the TCPC in vivo.
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Affiliation(s)
- T M Healy
- Georgia Tech/Emory University, Department of Biomedical Engineering, Atlanta 30332, USA
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