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Abbott RE, Nishimwe A, Wiputra H, Breighner RE, Ellingson AM. OrthoFusion: A Super-Resolution Algorithm to Fuse Orthogonal CT Volumes. Res Sq 2024:rs.3.rs-4117386. [PMID: 38645068 PMCID: PMC11030529 DOI: 10.21203/rs.3.rs-4117386/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
OrthoFusion, an intuitive super-resolution algorithm, is presented in this study to enhance the spatial resolution of clinical CT volumes. The efficacy of OrthoFusion is evaluated, relative to high-resolution CT volumes (ground truth), by assessing image volume and derived bone morphological similarity, as well as its performance in specific applications in 2D-3D registration tasks. Results demonstrate that OrthoFusion significantly reduced segmentation time, while improving structural similarity of bone images and relative accuracy of derived bone model geometries. Moreover, it proved beneficial in the context of biplane videoradiography, enhancing the similarity of digitally reconstructed radiographs to radiographic images and improving the accuracy of relative bony kinematics. OrthoFusion's simplicity, ease of implementation, and generalizability make it a valuable tool for researchers and clinicians seeking high spatial resolution from existing clinical CT data. This study opens new avenues for retrospectively utilizing clinical images for research and advanced clinical purposes, while reducing the need for additional scans, mitigating associated costs and radiation exposure.
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Wiputra H, Matsumoto S, Wagenseil JE, Braverman AC, Voeller RK, Barocas VH. Statistical shape representation of the thoracic aorta: accounting for major branches of the aortic arch. Comput Methods Biomech Biomed Engin 2023; 26:1557-1571. [PMID: 36165506 PMCID: PMC10040462 DOI: 10.1080/10255842.2022.2128672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 08/24/2022] [Accepted: 09/11/2022] [Indexed: 11/03/2022]
Abstract
Statistical shape modeling (SSM) is an emerging tool for risk assessment of thoracic aortic aneurysm. However, the head branches of the aortic arch are often excluded in SSM. We introduced an SSM strategy based on principal component analysis that accounts for aortic branches and applied it to a set of patient scans. Computational fluid dynamics were performed on the reconstructed geometries to identify the extent to which branch model accuracy affects the calculated wall shear stress (WSS) and pressure. Surface-averaged and location-specific values of pressure did not change significantly, but local WSS error was high near branches when inaccurately modeled.
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Affiliation(s)
- Hadi Wiputra
- Department of Biomedical Engineering, University of Minnesota
| | - Shion Matsumoto
- Department of Biomedical Engineering, University of Michigan
| | | | - Alan C. Braverman
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine
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Wong HS, Wiputra H, Tulzer A, Tulzer G, Yap CH. Fluid Mechanics of Fetal Left Ventricle During Aortic Stenosis with Evolving Hypoplastic Left Heart Syndrome. Ann Biomed Eng 2022; 50:1158-1172. [PMID: 35731342 PMCID: PMC9363377 DOI: 10.1007/s10439-022-02990-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 06/05/2022] [Indexed: 11/28/2022]
Abstract
In cases of fetal aortic stenosis and evolving Hypoplastic Left Heart Syndrome (feHLHS), aortic stenosis is associated with specific abnormalities such as retrograde or bidirectional systolic transverse arch flow. Many cases progressed to hypoplastic left heart syndrome (HLHS) malformation at birth, but fetal aortic valvuloplasty can prevent the progression in many cases. Since both disease and intervention involve drastic changes to the biomechanical environment, in-vivo biomechanics likely play a role in inducing and preventing disease progression. However, the fluid mechanics of feHLHS is not well-characterized. Here, we conduct patient-specific echocardiography-based flow simulations of normal and feHLHS left ventricles (LV), to understand the essential fluid dynamics distinction between the two cohorts. We found high variability across feHLHS cases, but also the following unifying features. Firstly, feHLHS diastole mitral inflow was in the form of a narrowed and fast jet that impinged onto the apical region, rather than a wide and gentle inflow in normal LVs. This was likely due to a malformed mitral valve with impaired opening dynamics. This altered inflow caused elevated vorticity dynamics and wall shear stresses (WSS) and reduced oscillatory shear index at the apical zone rather than mid-ventricle. Secondly, feHLHS LV also featured elevated systolic and diastolic energy losses, intraventricular pressure gradients, and vortex formation numbers, suggesting energy inefficiency of flow and additional burden on the LV. Thirdly, feHLHS LV had poor blood turnover, suggesting a hypoxic environment, which could be associated with endocardial fibroelastosis that is often observed in these patients.
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Affiliation(s)
- Hong Shen Wong
- Department of Bioengineering, Imperial College London, London, UK
| | - Hadi Wiputra
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Andreas Tulzer
- Department of Pediatric Cardiology, Children's Heart Center Linz, Kepler University Hospital, Linz, Austria
| | - Gerald Tulzer
- Department of Pediatric Cardiology, Children's Heart Center Linz, Kepler University Hospital, Linz, Austria
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, London, UK.
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Chan WX, Zheng Y, Wiputra H, Leo HL, Yap CH. Full cardiac cycle asynchronous temporal compounding of 3D echocardiography images. Med Image Anal 2021; 74:102229. [PMID: 34571337 DOI: 10.1016/j.media.2021.102229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/10/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
It is important to improve echocardiography image quality, because the accuracy of echocardiographic assessment and diagnosis relies on image quality. Previous work on 2D temporal image compounding for image frames with matching cardiac phases (synchronous), and for temporally neighbouring image frames (asynchronous) over small ranges of time frames showed good improvement to image quality. Here, we extend this by performing asynchronous temporal compounding to echocardiographic images in 3D, involving all frames within a cardiac cycle, via a robust 3D cardiac motion estimation algorithm to describe the large image deformations. After compounding, the images can be reanimated via the motion model. Various methods of fusing image frames together are tested, including mean, max, and wavelet methods, and outlier rejection algorithms. The compounding algorithm is applied on 3D human adult, porcine adolescent, and human fetal echocardiography images. Results show significant improvements to contrast-to-noise ratio (CNR) and boundary clarity, and significantly decreased variability in manual quantification of cardiac chamber volumes after compounding. Interestingly, compounding can extend the field of view of the echo images, by reconstructing cardiac structures that momentarily exceeded the field of view, using the motion estimation algorithm to calculate their locations outside the field of view during these time periods. Although all compounding methods provide general improvements, the mean method led to blurred boundaries, while the max methods led to high variability of CNR. Outlier rejection algorithms were found to be useful in addressing these weaknesses.
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Affiliation(s)
- Wei Xuan Chan
- Department of Biomedical Engineering, National University of Singapore, Singapore.
| | - Yu Zheng
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore.
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, London, UK.
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Foo YY, Motakis E, Tiang Z, Shen S, Lai JKH, Chan WX, Wiputra H, Chen N, Chen CK, Winkler C, Foo RSY, Yap CH. Effects of extended pharmacological disruption of zebrafish embryonic heart biomechanical environment on cardiac function, morphology, and gene expression. Dev Dyn 2021; 250:1759-1777. [PMID: 34056790 DOI: 10.1002/dvdy.378] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 04/24/2021] [Accepted: 05/13/2021] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Biomechanical stimuli are known to be important to cardiac development, but the mechanisms are not fully understood. Here, we pharmacologically disrupted the biomechanical environment of wild-type zebrafish embryonic hearts for an extended duration and investigated the consequent effects on cardiac function, morphological development, and gene expression. RESULTS Myocardial contractility was significantly diminished or abolished in zebrafish embryonic hearts treated for 72 hours from 2 dpf with 2,3-butanedione monoxime (BDM). Image-based flow simulations showed that flow wall shear stresses were abolished or significantly reduced with high oscillatory shear indices. At 5 dpf, after removal of BDM, treated embryonic hearts were maldeveloped, having disrupted cardiac looping, smaller ventricles, and poor cardiac function (lower ejected flow, bulboventricular regurgitation, lower contractility, and slower heart rate). RNA sequencing of cardiomyocytes of treated hearts revealed 922 significantly up-regulated genes and 1,698 significantly down-regulated genes. RNA analysis and subsequent qPCR and histology validation suggested that biomechanical disruption led to an up-regulation of inflammatory and apoptotic genes and down-regulation of ECM remodeling and ECM-receptor interaction genes. Biomechanics disruption also prevented the formation of ventricular trabeculation along with notch1 and erbb4a down-regulation. CONCLUSIONS Extended disruption of biomechanical stimuli caused maldevelopment, and potential genes responsible for this are identified.
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Affiliation(s)
- Yoke Yin Foo
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Efthymios Motakis
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Zenia Tiang
- Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore, Singapore
| | - Shuhao Shen
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Jason Kuan Han Lai
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Wei Xuan Chan
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Nanguang Chen
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Ching Kit Chen
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Division of Cardiology, Department of Paediatrics, Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore, Singapore
| | - Christoph Winkler
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Roger Sik Yin Foo
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore, Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.,Department of Bioengineering, Imperial College London, London, UK
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Wiputra H, Lim M, Yap CH. A transition point for the blood flow wall shear stress environment in the human fetal left ventricle during early gestation. J Biomech 2021; 120:110353. [PMID: 33730564 DOI: 10.1016/j.jbiomech.2021.110353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 02/03/2021] [Accepted: 02/22/2021] [Indexed: 11/24/2022]
Abstract
Development of the fetal heart is a fascinating process that involves a tremendous amount of growth. Here, we performed image-based flow simulations of 3 human fetal left ventricles (LV), and investigated the hypothetical scenario where the sizes of the hearts are scaled down, leading to reduced Reynolds number, to emulate earlier fetal stages. The shape and motion of the LV were retained over the scaling to isolate and understand the effects of length scaling on its fluid dynamics. We observed an interesting cut-off point in Reynolds number (Re), across which the dependency of LV wall shear stress (WSS) on Re changed. This was in line with classical fluid mechanic theory where skin friction coefficient exhibited first a decreasing trend and then a plateauing trend with increasing Re. Below this cut-off point, viscous effects dominated, stifling the formation of LV diastolic vorticity structures, and WSS was roughly independent of Reynolds number. However, above this cut-off, inertial effects dominated to cause diastolic vortex ring formation and detachment, and to cause WSS to scale linearly with Reynolds number. Results suggested that this transition point is found at approximately 11 weeks of gestation. Since WSS is thought to be a biomechanical stimuli for growth, this may have implications on normal fetal heart growth and malformation diseases like Hypoplastic Left Heart Syndrome.
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Affiliation(s)
- Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Morgan Lim
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, UK.
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Ong CW, Ren M, Wiputra H, Mojumder J, Chan WX, Tulzer A, Tulzer G, Buist ML, Mattar CNZ, Lee LC, Yap CH. Biomechanics of Human Fetal Hearts with Critical Aortic Stenosis. Ann Biomed Eng 2020; 49:1364-1379. [PMID: 33175989 PMCID: PMC8058006 DOI: 10.1007/s10439-020-02683-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022]
Abstract
Critical aortic stenosis (AS) of the fetal heart causes a drastic change in the cardiac biomechanical environment. Consequently, a substantial proportion of such cases will lead to a single-ventricular birth outcome. However, the biomechanics of the disease is not well understood. To address this, we performed Finite Element (FE) modelling of the healthy fetal left ventricle (LV) based on patient-specific 4D ultrasound imaging, and simulated various disease features observed in clinical fetal AS to understand their biomechanical impact. These features included aortic stenosis, mitral regurgitation (MR) and LV hypertrophy, reduced contractility, and increased myocardial stiffness. AS was found to elevate LV pressures and myocardial stresses, and depending on severity, can drastically decrease stroke volume and myocardial strains. These effects are moderated by MR. AS alone did not lead to MR velocities above 3 m/s unless LV hypertrophy was included, suggesting that hypertrophy may be involved in clinical cases with high MR velocities. LV hypertrophy substantially elevated LV pressure, valve flow velocities and stroke volume, while reducing LV contractility resulted in diminished LV pressure, stroke volume and wall strains. Typical extent of hypertrophy during fetal AS in the clinic, however, led to excessive LV pressure and valve velocity in the FE model, suggesting that reduced contractility is typically associated with hypertrophy. Increased LV passive stiffness, which might represent fibroelastosis, was found to have minimal impact on LV pressures, stroke volume, and wall strain. This suggested that fibroelastosis could be a by-product of the disease progression and does not significantly impede cardiac function. Our study demonstrates that FE modelling is a valuable tool for elucidating the biomechanics of congenital heart disease and can calculate parameters which are difficult to measure, such as intraventricular pressure and myocardial stresses.
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Affiliation(s)
- Chi Wei Ong
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Meifeng Ren
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Joy Mojumder
- Department of Mechanical Engineering, Michigan State University, East Lansing, United States
| | - Wei Xuan Chan
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Andreas Tulzer
- Department of Pediatric Cardiology, Children's Heart Center Linz, Kepler University Hospital, Linz, Austria
| | - Gerald Tulzer
- Department of Pediatric Cardiology, Children's Heart Center Linz, Kepler University Hospital, Linz, Austria
| | - Martin Lindsay Buist
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - Lik Chuan Lee
- Department of Mechanical Engineering, Michigan State University, East Lansing, United States
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, London, UK.
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Wiputra H, Chan WX, Foo YY, Ho S, Yap CH. Cardiac motion estimation from medical images: a regularisation framework applied on pairwise image registration displacement fields. Sci Rep 2020; 10:18510. [PMID: 33116206 PMCID: PMC7595231 DOI: 10.1038/s41598-020-75525-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 10/06/2020] [Indexed: 11/09/2022] Open
Abstract
Accurate cardiac motion estimation from medical images such as ultrasound is important for clinical evaluation. We present a novel regularisation layer for cardiac motion estimation that will be applied after image registration and demonstrate its effectiveness. The regularisation utilises a spatio-temporal model of motion, b-splines of Fourier, to fit to displacement fields from pairwise image registration. In the process, it enforces spatial and temporal smoothness and consistency, cyclic nature of cardiac motion, and better adherence to the stroke volume of the heart. Flexibility is further given for inclusion of any set of registration displacement fields. The approach gave high accuracy. When applied to human adult Ultrasound data from a Cardiac Motion Analysis Challenge (CMAC), the proposed method is found to have 10% lower tracking error over CMAC participants. Satisfactory cardiac motion estimation is also demonstrated on other data sets, including human fetal echocardiography, chick embryonic heart ultrasound images, and zebrafish embryonic microscope images, with the average Dice coefficient between estimation motion and manual segmentation at 0.82-0.87. The approach of performing regularisation as an add-on layer after the completion of image registration is thus a viable option for cardiac motion estimation that can still have good accuracy. Since motion estimation algorithms are complex, dividing up regularisation and registration can simplify the process and provide flexibility. Further, owing to a large variety of existing registration algorithms, such an approach that is usable on any algorithm may be useful.
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Affiliation(s)
- Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Wei Xuan Chan
- Department of Biomedical Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Yoke Yin Foo
- Department of Biomedical Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Sheldon Ho
- Department of Biomedical Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK.
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Zebhi B, Wiputra H, Howley L, Cuneo B, Park D, Hoffman H, Gilbert L, Yap CH, Bark D. Right ventricle in hypoplastic left heart syndrome exhibits altered hemodynamics in the human fetus. J Biomech 2020; 112:110035. [PMID: 32971490 DOI: 10.1016/j.jbiomech.2020.110035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 08/18/2020] [Accepted: 08/31/2020] [Indexed: 11/17/2022]
Abstract
Hypoplastic left heart syndrome (HLHS) represents approximately 9% of all congenital heart defects and is one of the most complex, with the left side of the heart being generally underdeveloped. Numerous studies demonstrate that intracardiac fluid flow patterns in the embryonic and fetal circulation can impact cardiac structural formation and remodeling. This highlights the importance of quantifying the altered hemodynamic environment in congenital heart defects, like HLHS, relative to a normal heart as it relates to cardiac development. Therefore, to study human cardiovascular fetal flow, computational fluid dynamic simulations were performed using 4D patient-specific ultrasound scans in normal and HLHS hearts. In these simulations, we find that the HLHS right ventricle exhibits a greater cardiac output than normal; yet, hemodynamics are relatively similar between normal and HLHS right ventricles. Overall, this study provides detailed quantitative flow patterns for HLHS, which has the potential to guide future prevention and therapeutic interventions, while more immediately providing additional functional detail to cardiologists to aid in decision making.
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Affiliation(s)
- Banafsheh Zebhi
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Lisa Howley
- The Children's Heart Clinic at the Children's Hospitals and Clinics of Minnesota, Minneapolis, MN, USA
| | - Bettina Cuneo
- The Colorado Fetal Care Center, Children's Hospital Colorado and the University of Colorado, Aurora, CO, USA
| | - Dawn Park
- The Colorado Fetal Care Center, Children's Hospital Colorado and the University of Colorado, Aurora, CO, USA
| | - Hilary Hoffman
- The Colorado Fetal Care Center, Children's Hospital Colorado and the University of Colorado, Aurora, CO, USA
| | - Lisa Gilbert
- The Colorado Fetal Care Center, Children's Hospital Colorado and the University of Colorado, Aurora, CO, USA
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, UK
| | - David Bark
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA; School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA; Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Pediatrics, Washington University in Saint Louis, Saint Louis, MO, USA.
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10
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Vasudevan V, Wiputra H, Yap CH. Torsional motion of the left ventricle does not affect ventricular fluid dynamics of both foetal and adult hearts. J Biomech 2019; 96:109357. [PMID: 31635847 DOI: 10.1016/j.jbiomech.2019.109357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 08/05/2019] [Accepted: 09/18/2019] [Indexed: 11/17/2022]
Abstract
Left ventricular torsion is caused by shortening and relaxation of the helical fibres in the myocardium, and is thought to be an optimal configuration for minimizing myocardial tissue strains. Characteristics of torsional motion has also been proposed to be markers for cardiac dysfunction. However, its effects on fluid and energy dynamics in the left ventricle have not been comprehensively investigated. To investigate this, we performed image-based flow simulations on five healthy adult porcine and two healthy human foetal left ventricles (representing two different length scales) at different degrees of torsional motions. In the adult porcine ventricles, cardiac features such as papillary muscles and mitral valves, and cardiac conditions such as myocardial infarctions, were also included to investigate the effect of twist. The results showed that, for all conditions investigated, ventricular torsional motion caused minimal changes to flow patterns, and consistently accounted for less than 2% of the energy losses, wall shear stresses, and ejection momentum energy. In contrast, physiological characteristics such as chamber size, stroke volume and heart rate had a much greater influence on flow patterns and energy dynamics. The results thus suggested that it might not be necessary to model the torsional motion to study the flow and energy dynamics in left ventricles.
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Affiliation(s)
- Vivek Vasudevan
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore.
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Wiputra H, Chen CK, Talbi E, Lim GL, Soomar SM, Biswas A, Mattar CNZ, Bark D, Leo HL, Yap CH. Human fetal hearts with tetralogy of Fallot have altered fluid dynamics and forces. Am J Physiol Heart Circ Physiol 2018; 315:H1649-H1659. [PMID: 30216114 DOI: 10.1152/ajpheart.00235.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Studies have suggested the effect of blood flow forces in pathogenesis and progression of some congenital heart malformations. It is therefore of interest to study the fluid mechanic environment of the malformed prenatal heart, such as the tetralogy of Fallot (TOF), especially when little is known about fetal TOF. In this study, we performed patient-specific ultrasound-based flow simulations of three TOF and seven normal human fetal hearts. TOF right ventricles (RVs) had smaller end-diastolic volumes (EDVs) but similar stroke volumes (SVs), whereas TOF left ventricles (LVs) had similar EDVs but slightly increased SVs compared with normal ventricles. Simulations showed that TOF ventricles had elevated systolic intraventricular pressure gradient (IVPG) and required additional energy for ejection but IVPG elevations were considered to be mild relative to arterial pressure. TOF RVs and LVs had similar pressures because of equalization via ventricular septal defect (VSD). Furthermore, relative to normal, TOF RVs had increased diastolic wall shear stresses (WSS) but TOF LVs were not. This was caused by high tricuspid inflow that exceeded RV SV, leading to right-to-left shunting and chaotic flow with enhanced vorticity interaction with the wall to elevate WSS. Two of the three TOF RVs but none of the LVs had increased thickness. As pressure elevations were mild, we hypothesized that pressure and WSS elevation could play a role in the RV thickening, among other causative factors. Finally, the endocardium surrounding the VSD consistently experienced high WSS because of RV-to-LV flow shunt and high flow rate through the over-riding aorta. NEW & NOTEWORTHY Blood flow forces are thought to cause congenital heart malformations and influence disease progression. We performed novel investigations of intracardiac fluid mechanics of tetralogy of Fallot (TOF) human fetal hearts and found essential differences from normal hearts. The TOF right ventricle (RV) and left ventricle had similar and elevated pressure but only the TOF RV had elevated wall shear stress because of elevated tricuspid inflow, and this may contribute to the observed RV thickening. TOF hearts also expended more energy for ejection.
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Affiliation(s)
- Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore , Singapore
| | - Ching Kit Chen
- Division of Cardiology, Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System , Singapore
| | - Elias Talbi
- Department of Biomedical Engineering, National University of Singapore , Singapore
| | - Guat Ling Lim
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System , Singapore
| | - Sanah Merchant Soomar
- Division of Cardiology, Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System , Singapore
| | - Arijit Biswas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System , Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System , Singapore
| | - David Bark
- Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore , Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore , Singapore
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Wiputra H, Lim GL, Chua KC, Nivetha R, Soomar SM, Biwas A, Mattar CNZ, Leo HL, Yap CH. Peristaltic-Like Motion of the Human Fetal Right Ventricle and its Effects on Fluid Dynamics and Energy Dynamics. Ann Biomed Eng 2017; 45:2335-2347. [DOI: 10.1007/s10439-017-1886-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/11/2017] [Indexed: 10/19/2022]
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13
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Wiputra H, Lai CQ, Lim GL, Heng JJW, Guo L, Soomar SM, Leo HL, Biwas A, Mattar CNZ, Yap CH. Fluid mechanics of human fetal right ventricles from image-based computational fluid dynamics using 4D clinical ultrasound scans. Am J Physiol Heart Circ Physiol 2016; 311:H1498-H1508. [DOI: 10.1152/ajpheart.00400.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/08/2016] [Indexed: 11/22/2022]
Abstract
There are 0.6–1.9% of US children who were born with congenital heart malformations. Clinical and animal studies suggest that abnormal blood flow forces might play a role in causing these malformation, highlighting the importance of understanding the fetal cardiovascular fluid mechanics. We performed computational fluid dynamics simulations of the right ventricles, based on four-dimensional ultrasound scans of three 20-wk-old normal human fetuses, to characterize their flow and energy dynamics. Peak intraventricular pressure gradients were found to be 0.2–0.9 mmHg during systole, and 0.1–0.2 mmHg during diastole. Diastolic wall shear stresses were found to be around 1 Pa, which could elevate to 2–4 Pa during systole in the outflow tract. Fetal right ventricles have complex flow patterns featuring two interacting diastolic vortex rings, formed during diastolic E wave and A wave. These rings persisted through the end of systole and elevated wall shear stresses in their proximity. They were observed to conserve ∼25.0% of peak diastolic kinetic energy to be carried over into the subsequent systole. However, this carried-over kinetic energy did not significantly alter the work done by the heart for ejection. Thus, while diastolic vortexes played a significant role in determining spatial patterns and magnitudes of diastolic wall shear stresses, they did not have significant influence on systolic ejection. Our results can serve as a baseline for future comparison with diseased hearts.
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Affiliation(s)
- Hadi Wiputra
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Chang Quan Lai
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Guat Ling Lim
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Joel Jia Wei Heng
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Lan Guo
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sanah Merchant Soomar
- Division of Pediatric Cardiology, Koo Teck Phuat, National University Children's Medical Institute, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore; and
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Arijit Biwas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore
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