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Liu H, Sacks MS, Simonian NT, Gorman JH, Gorman RC. Simulated Effects of Acute Left Ventricular Myocardial Infarction on Mitral Regurgitation in an Ovine Model. J Biomech Eng 2024; 146:101009. [PMID: 38652602 PMCID: PMC11225881 DOI: 10.1115/1.4065376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 04/12/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Ischemic mitral regurgitation (IMR) occurs from incomplete coaptation of the mitral valve (MV) after myocardial infarction (MI), typically worsened by continued remodeling of the left ventricular (LV). The importance of LV remodeling is clear as IMR is induced by the post-MI dual mechanisms of mitral annular dilation and leaflet tethering from papillary muscle (PM) distension via the MV chordae tendineae (MVCT). However, the detailed etiology of IMR remains poorly understood, in large part due to the complex interactions of the MV and the post-MI LV remodeling processes. Given the patient-specific anatomical complexities of the IMR disease processes, simulation-based approaches represent an ideal approach to improve our understanding of this deadly disease. However, development of patient-specific models of left ventricle-mitral valve (LV-MV) interactions in IMR are complicated by the substantial variability and complexity of the MR etiology itself, making it difficult to extract underlying mechanisms from clinical data alone. To address these shortcomings, we developed a detailed ovine LV-MV finite element (FE) model based on extant comprehensive ovine experimental data. First, an extant ovine LV FE model (Sci. Rep. 2021 Jun 29;11(1):13466) was extended to incorporate the MV using a high fidelity ovine in vivo derived MV leaflet geometry. As it is not currently possible to image the MVCT in vivo, a functionally equivalent MVCT network was developed to create the final LV-MV model. Interestingly, in pilot studies, the MV leaflet strains did not agree well with known in vivo MV leaflet strain fields. We then incorporated previously reported MV leaflet prestrains (J. Biomech. Eng. 2023 Nov 1;145(11):111002) in the simulations. The resulting LV-MV model produced excellent agreement with the known in vivo ovine MV leaflet strains and deformed shapes in the normal state. We then simulated the effects of regional acute infarctions of varying sizes and anatomical locations by shutting down the local myocardial contractility. The remaining healthy (noninfarcted) myocardium mechanical behaviors were maintained, but allowed to adjust their active contractile patterns to maintain the prescribed pressure-volume loop behaviors in the acute post-MI state. For all cases studied, the LV-MV simulation demonstrated excellent agreement with known LV and MV in vivo strains and MV regurgitation orifice areas. Infarct location was shown to play a critical role in resultant MV leaflet strain fields. Specifically, extensional deformations of the posterior leaflets occurred in the posterobasal and laterobasal infarcts, while compressive deformations of the anterior leaflet were observed in the anterobasal infarct. Moreover, the simulated posterobasal infarct induced the largest MV regurgitation orifice area, consistent with experimental observations. The present study is the first detailed LV-MV simulation that reveals the important role of MV leaflet prestrain and functionally equivalent MVCT for accurate predictions of LV-MV interactions. Importantly, the current study further underscored simulation-based methods in understanding MV function as an integral part of the LV.
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Affiliation(s)
- Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, The Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Michael S. Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, The Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Natalie T. Simonian
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, The Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Joseph H. Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, PA 19146-2701
| | - Robert C. Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, PA 19146-2701
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Zuo H, Feng W, Tang X, Li Z, Fan Y. The study of loading mode with in-vitro fatigue testing for mitral annuloplasty ring. J Biomech 2024; 166:112047. [PMID: 38484653 DOI: 10.1016/j.jbiomech.2024.112047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/23/2024] [Accepted: 03/07/2024] [Indexed: 04/13/2024]
Abstract
To maintain the physiological dynamics of the mitral annulus, mitral annuloplasty rings (MAR) must be flexible. Enhanced flexibility implies decreased resistance to fatigue and potential for fatigue fracture. This study established new methods to test the flexible fatigue life of MAR in-vitro using numerical analysis; the purpose is that the fatigue test could reflect the real stress distribution in-vivo. Based on the conventional test methods (C1, D1), this paper presents a novel test method (C2, D2). Four testing methods for open-end annuloplasty rings (C1, C2) and closed-end annuloplasty rings (D1, D2) were modelled and their stress distribution calculated by finite element analysis. The mean absolute error (Χ) and the Pearson correlation coefficient (Φ) were used to quantify the difference in stress distribution between the loading modes in-vivo and in-vitro. For closed-end annuloplasty rings, the novel test method (D2) is not obvious better than conventional test methods(D1) in duplicating the stress distribution (ΦD1 = 0.88 vs ΦD2 = 0.92). However, the maximum values of stress in the novel test method are closer to the maximum value of stress under in-vivo loading (ΧD1 = 5.2Mpa vs ΧD2 = 4.4Mpa). For open-end annuloplasty rings, the novel test method(C2) is obviously superior to the conventional test method(C1) in duplicating both the stress distribution and the stress peak values of the in-vivo loading (ΦC1 = 0.22 vs ΦC2 = 0.98; ΧC1 = 59.1Mpa vs ΧC2 = 11.0Mpa). The in-vitro loading methods described in this article more closely approximated in-vivo conditions compared to traditional methods. They are simpler to operate, more efficient and can help manufacturers expedite new product development, assist regulatory agencies with product quality oversight.
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Affiliation(s)
- Hui Zuo
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China
| | - Wentao Feng
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China.
| | - Xiaolan Tang
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China
| | - Zhou Li
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China
| | - Yubo Fan
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China.
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Fumagalli I, Pagani S, Vergara C, Dede’ L, Adebo DA, Del Greco M, Frontera A, Luciani GB, Pontone G, Scrofani R, Quarteroni A. The role of computational methods in cardiovascular medicine: a narrative review. Transl Pediatr 2024; 13:146-163. [PMID: 38323181 PMCID: PMC10839285 DOI: 10.21037/tp-23-184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 12/13/2023] [Indexed: 02/08/2024] Open
Abstract
Background and Objective Computational models of the cardiovascular system allow for a detailed and quantitative investigation of both physiological and pathological conditions, thanks to their ability to combine clinical-possibly patient-specific-data with physical knowledge of the processes underlying the heart function. These models have been increasingly employed in clinical practice to understand pathological mechanisms and their progression, design medical devices, support clinicians in improving therapies. Hinging upon a long-year experience in cardiovascular modeling, we have recently constructed a computational multi-physics and multi-scale integrated model of the heart for the investigation of its physiological function, the analysis of pathological conditions, and to support clinicians in both diagnosis and treatment planning. This narrative review aims to systematically discuss the role that such model had in addressing specific clinical questions, and how further impact of computational models on clinical practice are envisaged. Methods We developed computational models of the physical processes encompassed by the heart function (electrophysiology, electrical activation, force generation, mechanics, blood flow dynamics, valve dynamics, myocardial perfusion) and of their inherently strong coupling. To solve the equations of such models, we devised advanced numerical methods, implemented in a flexible and highly efficient software library. We also developed computational procedures for clinical data post-processing-like the reconstruction of the heart geometry and motion from diagnostic images-and for their integration into computational models. Key Content and Findings Our integrated computational model of the heart function provides non-invasive measures of indicators characterizing the heart function and dysfunctions, and sheds light on its underlying processes and their coupling. Moreover, thanks to the close collaboration with several clinical partners, we addressed specific clinical questions on pathological conditions, such as arrhythmias, ventricular dyssynchrony, hypertrophic cardiomyopathy, degeneration of prosthetic valves, and the way coronavirus disease 2019 (COVID-19) infection may affect the cardiac function. In multiple cases, we were also able to provide quantitative indications for treatment. Conclusions Computational models provide a quantitative and detailed tool to support clinicians in patient care, which can enhance the assessment of cardiac diseases, the prediction of the development of pathological conditions, and the planning of treatments and follow-up tests.
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Affiliation(s)
- Ivan Fumagalli
- MOX Laboratory, Department of Mathematics, Politecnico di Milano, Milan, Italy
| | - Stefano Pagani
- MOX Laboratory, Department of Mathematics, Politecnico di Milano, Milan, Italy
| | - Christian Vergara
- Laboratory of Biological Structures Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Luca Dede’
- MOX Laboratory, Department of Mathematics, Politecnico di Milano, Milan, Italy
| | - Dilachew A. Adebo
- Children’s Heart Institute, Hermann Children’s Hospital, University of Texas Health Science Center, McGovern Medical School, Houston, TX, USA
| | - Maurizio Del Greco
- Department of Cardiology, S. Maria del Carmine Hospital, Rovereto, Italy
| | - Antonio Frontera
- Electrophysiology Department, De Gasperis Cardio Center, ASST Great Metropolitan Hospital Niguarda, Milan, Italy
| | | | - Gianluca Pontone
- Department of Perioperative Cardiology and Cardiovascular Imaging, Centro Cardiologico Monzino IRCSS, Milan, Italy
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy
| | - Roberto Scrofani
- Cardiovascular Department, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Alfio Quarteroni
- MOX Laboratory, Department of Mathematics, Politecnico di Milano, Milan, Italy
- Institute of Mathematics, École Polytechnique Fédérale de Lausanne, Switzerland
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Didagelos M, Friderikos O, Ziakas A, David C, Sagris D, Pagiantza A, Karvounis H. Mitral valve geometrical echocardiographic analysis and 3D computational modeling of a normal mitral valve. Future Cardiol 2023; 19:453-467. [PMID: 37815033 DOI: 10.2217/fca-2021-0157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023] Open
Abstract
Aim: This research aims to develop a consistent computational model of a normal mitral valve (MV) and describe mitral regurgitation (MR) geometry based on Carpentier's classification. Materials & methods: MV geometry was assessed by 2D transthoracic echocardiogram in 100 individuals. A 3D parametric geometric model of the MV was developed. A computational model of a normal MV was performed. Results: The simulation of the valve function was successfully accomplished and its kinematics was analyzed. Differences in geometry were revealed between normal and type III MR. Conclusion: 3D computational models of the normal MV can be constructed relying on standard measurements performed by 2D echocardiography. Certain geometrical differences exist among the normal and the most severe type of MR.
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Affiliation(s)
- Matthaios Didagelos
- 1st Cardiology Department, AHEPA University General Hospital, Aristotle University of Thessaloniki, 54636, Greece
| | - Orestis Friderikos
- Mechanical Engineering Department, International Hellenic University, Serres, 62124, Greece
| | - Antonios Ziakas
- 1st Cardiology Department, AHEPA University General Hospital, Aristotle University of Thessaloniki, 54636, Greece
| | - Constantine David
- Mechanical Engineering Department, International Hellenic University, Serres, 62124, Greece
| | - Dimitrios Sagris
- Mechanical Engineering Department, International Hellenic University, Serres, 62124, Greece
| | - Areti Pagiantza
- 1st Cardiology Department, AHEPA University General Hospital, Aristotle University of Thessaloniki, 54636, Greece
| | - Haralambos Karvounis
- 1st Cardiology Department, AHEPA University General Hospital, Aristotle University of Thessaloniki, 54636, Greece
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Computational analysis of ventricular mechanics in hypertrophic cardiomyopathy patients. Sci Rep 2023; 13:958. [PMID: 36653468 PMCID: PMC9849405 DOI: 10.1038/s41598-023-28037-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 01/11/2023] [Indexed: 01/19/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a genetic heart disease that is associated with many pathological features, such as a reduction in global longitudinal strain (GLS), myofiber disarray and hypertrophy. The effects of these features on left ventricle (LV) function are, however, not clear in two phenotypes of HCM, namely, obstructive and non-obstructive. To address this issue, we developed patient-specific computational models of the LV using clinical measurements from 2 female HCM patients and a control subject. Left ventricular mechanics was described using an active stress formulation and myofiber disarray was described using a structural tensor in the constitutive models. Unloaded LV configuration for each subject was first determined from their respective end-diastole LV geometries segmented from the cardiac magnetic resonance images, and an empirical single-beat estimation of the end-diastolic pressure volume relationship. The LV was then connected to a closed-loop circulatory model and calibrated using the clinically measured LV pressure and volume waveforms, peak GLS and blood pressure. Without consideration of myofiber disarray, peak myofiber tension was found to be lowest in the obstructive HCM subject (60 kPa), followed by the non-obstructive subject (242 kPa) and the control subject (375 kPa). With increasing myofiber disarray, we found that peak tension has to increase in the HCM models to match the clinical measurements. In the obstructive HCM patient, however, peak tension was still depressed (cf. normal subject) at the largest degree of myofiber disarray found in the clinic. The computational modeling workflow proposed here can be used in future studies with more HCM patient data.
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Capelli C, Bertolini M, Schievano S. 3D-printed and computational models: a combined approach for patient-specific studies. 3D Print Med 2023. [DOI: 10.1016/b978-0-323-89831-7.00011-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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Galili L, Weissmann J, White Zeira A, Marom G. Numerical modeling for efficiency and endurance assessment of an indirect mitral annuloplasty device. J Mech Behav Biomed Mater 2022; 136:105516. [PMID: 36215769 DOI: 10.1016/j.jmbbm.2022.105516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/02/2022] [Accepted: 10/03/2022] [Indexed: 11/06/2022]
Abstract
In recent years, several transcatheter systems have been introduced for treatment of common mitral regurgitation (MR). Such a system that is based on indirect mitral annuloplasty (IMA) is currently indicated for functional MR. Very few clinical studies have been performed to assess the efficiency and durability of such devices, despite their high risk of fracture resulting from ongoing exposure to large cyclic deformations. In this study, numerical models of moderate primary MR were created to test the implantation procedure of a customized IMA device and its sealing efficiency. The ability of the implanted device to reduce systolic leakage was evaluated and affirmed with a model of a more generic device. The long-term durability of the device was tested using a range of Nickel Titanium material properties. Our results demonstrated a considerable reduction in leakage for both the simplified generic device and the more detailed customized device models. The device met different fatigue criteria, confirming its resiliency and safety even after 10 years, even under the harsher conditions of primary MR. This is the first study to assess the performance and fatigue risk of IMA devices for the treatment of more complicated MR conditions. These findings may pave the way for further research to ultimately consider the device in selective cases of PMR.
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Affiliation(s)
- Lee Galili
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Jonathan Weissmann
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Adi White Zeira
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Gil Marom
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel.
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8
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Pasta S, Catalano C, Cannata S, Guccione JM, Gandolfo C. Numerical simulation of transcatheter mitral valve replacement: The dynamic implication of LVOT obstruction in the valve-in-ring case. J Biomech 2022; 144:111337. [DOI: 10.1016/j.jbiomech.2022.111337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 09/21/2022] [Accepted: 09/27/2022] [Indexed: 11/26/2022]
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A Computationally Efficient Approach to Simulate Heart Rate Effects Using a Whole Human Heart Model. Bioengineering (Basel) 2022; 9:bioengineering9080334. [PMID: 35892747 PMCID: PMC9331290 DOI: 10.3390/bioengineering9080334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/12/2022] [Accepted: 07/20/2022] [Indexed: 11/17/2022] Open
Abstract
Computational modeling of the whole human heart has become a valuable tool to evaluate medical devices such as leadless pacemakers, annuloplasty rings and left ventricular assist devices, since it is often difficult to replicate the complex dynamic interactions between the device and human heart in bench-top and animal tests. The Dassault Systèmes Living Heart Human Model (LHHM) is a finite-element model of whole-human-heart electromechanics that has input parameters that were previously calibrated to generate physiological responses in a healthy heart beating at 60 beat/min (resting state). This study demonstrates that, by adjusting only six physiologically meaningful parameters, the LHHM can be recalibrated to generate physiological responses in a healthy heart beating at heart rates ranging from 90−160 beat/min. These parameters are as follows: the sinoatrial node firing period decreases from 0.67 s at 90 bpm to 0.38 s at 160 bpm, atrioventricular delay decreases from 0.122 s at 90 bpm to 0.057 s at 160 bpm, preload increases 3-fold from 90 bpm to 160 bpm, body resistance at 160 bpm is 80% of that at 90 bpm, arterial stiffness at 160 bpm is 3.9 times that at 90 bpm, and a parameter relating myofiber twitch force duration and sarcomere length decreases from 238 ms/mm at 90 bpm to 175 ms/mm at 160 bpm. In addition, this study demonstrates the feasibility of using the LHHM to conduct clinical investigations in AV delay optimization and hemodynamic differences between pacing and exercise. AV delays in the ranges of 40 ms to 250 ms were simulated and stroke volume and systolic blood pressure showed clear peaks at 120 ms for 90 bpm. For a heart during exercise, the increase in cardiac output continues to 160 bpm. However, for a heart during pacing, those physiological parameter adjustments are removed that are related to changes in body oxygen requirements (preload, arterial stiffness and body resistance). Consequently, cardiac output increases initially with heart rate; as the heart rate goes up (>100 bpm), the increasing rate of cardiac output slows down and approaches a plateau.
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Guan D, Wang Y, Xu L, Cai L, Luo X, Gao H. Effects of dispersed fibres in myocardial mechanics, Part II: active response. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2022; 19:4101-4119. [PMID: 35341289 DOI: 10.3934/mbe.2022189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This work accompanies the first part of our study "effects of dispersed fibres in myocardial mechanics: Part I passive response" with a focus on myocardial active contraction. Existing studies have suggested that myofibre architecture plays an important role in myocardial active contraction. Following the first part of our study, we firstly study how the general fibre architecture affects ventricular pump function by varying the mean myofibre rotation angles, and then the impact of fibre dispersion along the myofibre direction on myocardial contraction in a left ventricle model. Dispersed active stress is described by a generalised structure tensor method for its computational efficiency. Our results show that both the myofibre rotation angle and its dispersion can significantly affect cardiac pump function by redistributing active tension circumferentially and longitudinally. For example, larger myofibre rotation angle and higher active tension along the sheet-normal direction can lead to much reduced end-systolic volume and higher longitudinal shortening, and thus a larger ejection fraction. In summary, these two studies together have demonstrated that it is necessary and essential to include realistic fibre structures (both fibre rotation angle and fibre dispersion) in personalised cardiac modelling for accurate myocardial dynamics prediction.
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Affiliation(s)
- Debao Guan
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Yingjie Wang
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Lijian Xu
- Centre for Perceptual and Interactive Intelligence, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Cai
- School of Mathematics and Statistics, Northwestern Polytechnical University, Xi'an, China
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, UK
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Martonová D, Holz D, Seufert J, Duong MT, Alkassar M, Leyendecker S. Comparison of stress and stress–strain approaches for the active contraction in a rat cardiac cycle model. J Biomech 2022; 134:110980. [DOI: 10.1016/j.jbiomech.2022.110980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/17/2022]
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Galili L, White Zeira A, Marom G. Numerical biomechanics modelling of indirect mitral annuloplasty treatments for functional mitral regurgitation. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211464. [PMID: 35242347 PMCID: PMC8753151 DOI: 10.1098/rsos.211464] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 12/14/2021] [Indexed: 05/03/2023]
Abstract
Mitral valve regurgitation (MR) is a common valvular heart disease where an improper closure leads to leakage from the left ventricle into the left atrium. There is a need for less-invasive treatments such as percutaneous repairs for a large inoperable patient population. The aim of this study is to compare several indirect mitral annuloplasty (IMA) percutaneous repair techniques by finite-element analyses. Two types of generic IMA devices were considered, based on coronary sinus vein shortening (IMA-CS) to reduce the annulus perimeter and based on shortening of the anterior-posterior diameter (IMA-AP). The disease, its treatments, and the heart function post-repair were modelled by modifying the living heart human model (Dassault Systèmes). A functional MR pathology that represents ischaemic MR was generated and the IMA treatments were simulated in it, followed by heart function simulations with the devices and leakage quantification from blood flow simulations. All treatments were able to reduce leakage, the IMA-AP device achieved better sealing, and there was a correlation between the IMA-CS device length and the reduction in leakage. The results of this study can help in bringing IMA-AP to market, expanding the use of IMA devices, and optimizing future designs of such devices.
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Affiliation(s)
- Lee Galili
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Adi White Zeira
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Gil Marom
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
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Patient-Specific Analysis of Ascending Thoracic Aortic Aneurysm with the Living Heart Human Model. Bioengineering (Basel) 2021; 8:bioengineering8110175. [PMID: 34821741 PMCID: PMC8615119 DOI: 10.3390/bioengineering8110175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/26/2021] [Accepted: 11/03/2021] [Indexed: 01/11/2023] Open
Abstract
In ascending thoracic aortic aneurysms (ATAAs), aneurysm kinematics are driven by ventricular traction occurring every heartbeat, increasing the stress level of dilated aortic wall. Aortic elongation due to heart motion and aortic length are emerging as potential indicators of adverse events in ATAAs; however, simulation of ATAA that takes into account the cardiac mechanics is technically challenging. The objective of this study was to adapt the realistic Living Heart Human Model (LHHM) to the anatomy and physiology of a patient with ATAA to assess the role of cardiac motion on aortic wall stress distribution. Patient-specific segmentation and material parameter estimation were done using preoperative computed tomography angiography (CTA) and ex vivo biaxial testing of the harvested tissue collected during surgery. The lumped-parameter model of systemic circulation implemented in the LHHM was refined using clinical and echocardiographic data. The results showed that the longitudinal stress was highest in the major curvature of the aneurysm, with specific aortic quadrants having stress levels change from tensile to compressive in a transmural direction. This study revealed the key role of heart motion that stretches the aortic root and increases ATAA wall tension. The ATAA LHHM is a realistic cardiovascular platform where patient-specific information can be easily integrated to assess the aneurysm biomechanics and potentially support the clinical management of patients with ATAAs.
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Kreuzer SM, Briant PL, Ochoa JA. Establishing the Biofidelity of a Multiphysics Finite Element Model of the Human Heart. Cardiovasc Eng Technol 2021; 12:387-397. [PMID: 33851325 DOI: 10.1007/s13239-021-00538-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 04/05/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE Accelerating development of new therapeutic cardiac devices remains a clinical and technical priority. High-performance computing and the emergence of functional and complex in silico models of human anatomy can be an engine to accelerate the commercialization of innovative, safe, and effective devices. METHODS An existing three-dimensional, nonlinear model of a human heart with flow boundary conditions was evaluated. Its muscular tissues were exercised using electrophysiological boundary conditions, creating a dynamic, electro-mechanical simulation of the kinetics of the human heart. Anatomic metrics were selected to characterize the functional biofidelity of the model based on their significance to the design of cardiac devices. The model output was queried through the cardiac cycle and compared to in vivo literature values. RESULTS For the kinematics of mitral and aortic valves and curvature of coronary vessels, the model's performance was at or above the 95th percentile range of the in vivo data from large patient cohorts. One exception was the kinematics of the tricuspid valve. The model's mechanical use environment would subject devices to generally conservative use conditions. CONCLUSIONS This conservative simulated use environment for heart-based medical devices, and its judicious application in the evaluation of medical devices is justified, but careful interpretation of the results is encouraged.
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Affiliation(s)
- Steven M Kreuzer
- Mechanical Engineering Practice, Exponent, Inc., 1075 Worcester St, Natick, MA, 01760, USA
| | - Paul L Briant
- Mechanical Engineering Practice, Exponent, Inc., 149 Commonwealth Drive, Menlo Park, CA, 94025, USA
| | - Jorge A Ochoa
- Biomedical Engineering and Sciences Practice, Exponent, Inc., 1250 S Capital of Texas Hwy, Bldg. 3, Ste. 400, Austin, TX, 78746, USA.
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Vardhan M, Randles A. Application of physics-based flow models in cardiovascular medicine: Current practices and challenges. BIOPHYSICS REVIEWS 2021; 2:011302. [PMID: 38505399 PMCID: PMC10903374 DOI: 10.1063/5.0040315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/18/2021] [Indexed: 03/21/2024]
Abstract
Personalized physics-based flow models are becoming increasingly important in cardiovascular medicine. They are a powerful complement to traditional methods of clinical decision-making and offer a wealth of physiological information beyond conventional anatomic viewing using medical imaging data. These models have been used to identify key hemodynamic biomarkers, such as pressure gradient and wall shear stress, which are associated with determining the functional severity of cardiovascular diseases. Importantly, simulation-driven diagnostics can help researchers understand the complex interplay between geometric and fluid dynamic parameters, which can ultimately improve patient outcomes and treatment planning. The possibility to compute and predict diagnostic variables and hemodynamics biomarkers can therefore play a pivotal role in reducing adverse treatment outcomes and accelerate development of novel strategies for cardiovascular disease management.
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Affiliation(s)
- M. Vardhan
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - A. Randles
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
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16
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Precision medicine in human heart modeling : Perspectives, challenges, and opportunities. Biomech Model Mechanobiol 2021; 20:803-831. [PMID: 33580313 PMCID: PMC8154814 DOI: 10.1007/s10237-021-01421-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/07/2021] [Indexed: 01/05/2023]
Abstract
Precision medicine is a new frontier in healthcare that uses scientific methods to customize medical treatment to the individual genes, anatomy, physiology, and lifestyle of each person. In cardiovascular health, precision medicine has emerged as a promising paradigm to enable cost-effective solutions that improve quality of life and reduce mortality rates. However, the exact role in precision medicine for human heart modeling has not yet been fully explored. Here, we discuss the challenges and opportunities for personalized human heart simulations, from diagnosis to device design, treatment planning, and prognosis. With a view toward personalization, we map out the history of anatomic, physical, and constitutive human heart models throughout the past three decades. We illustrate recent human heart modeling in electrophysiology, cardiac mechanics, and fluid dynamics and highlight clinically relevant applications of these models for drug development, pacing lead failure, heart failure, ventricular assist devices, edge-to-edge repair, and annuloplasty. With a view toward translational medicine, we provide a clinical perspective on virtual imaging trials and a regulatory perspective on medical device innovation. We show that precision medicine in human heart modeling does not necessarily require a fully personalized, high-resolution whole heart model with an entire personalized medical history. Instead, we advocate for creating personalized models out of population-based libraries with geometric, biological, physical, and clinical information by morphing between clinical data and medical histories from cohorts of patients using machine learning. We anticipate that this perspective will shape the path toward introducing human heart simulations into precision medicine with the ultimate goals to facilitate clinical decision making, guide treatment planning, and accelerate device design.
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17
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Dabiri Y, Van der Velden A, Sack KL, Choy JS, Guccione JM, Kassab GS. Application of feed forward and recurrent neural networks in simulation of left ventricular mechanics. Sci Rep 2020; 10:22298. [PMID: 33339836 PMCID: PMC7749109 DOI: 10.1038/s41598-020-79191-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 11/19/2020] [Indexed: 11/25/2022] Open
Abstract
An understanding of left ventricle (LV) mechanics is fundamental for designing better preventive, diagnostic, and treatment strategies for improved heart function. Because of the costs of clinical and experimental studies to treat and understand heart function, respectively, in-silico models play an important role. Finite element (FE) models, which have been used to create in-silico LV models for different cardiac health and disease conditions, as well as cardiac device design, are time-consuming and require powerful computational resources, which limits their use when real-time results are needed. As an alternative, we sought to use deep learning (DL) for LV in-silico modeling. We used 80 four-chamber heart FE models for feed forward, as well as recurrent neural network (RNN) with long short-term memory (LSTM) models for LV pressure and volume. We used 120 LV-only FE models for training LV stress predictions. The active material properties of the myocardium and time were features for the LV pressure and volume training, and passive material properties and element centroid coordinates were features of the LV stress prediction models. For six test FE models, the DL error for LV volume was 1.599 ± 1.227 ml, and the error for pressure was 1.257 ± 0.488 mmHg; for 20 LV FE test examples, the mean absolute errors were, respectively, 0.179 ± 0.050 for myofiber, 0.049 ± 0.017 for cross-fiber, and 0.039 ± 0.011 kPa for shear stress. After training, the DL runtime was in the order of seconds whereas equivalent FE runtime was in the order of several hours (pressure and volume) or 20 min (stress). We conclude that using DL, LV in-silico simulations can be provided for applications requiring real-time results.
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Affiliation(s)
- Yaghoub Dabiri
- 3DT Holdings LLC, San Diego, CA, USA
- California Medical Innovations Institute, 11107 Roselle, San Diego, CA, 92121, USA
| | | | - Kevin L Sack
- Department of Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Jenny S Choy
- California Medical Innovations Institute, 11107 Roselle, San Diego, CA, 92121, USA
| | - Julius M Guccione
- Department of Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Ghassan S Kassab
- California Medical Innovations Institute, 11107 Roselle, San Diego, CA, 92121, USA.
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18
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Mathur M, Malinowski M, Timek TA, Rausch MK. Tricuspid Annuloplasty Rings: A Quantitative Comparison of Size, Nonplanar Shape, and Stiffness. Ann Thorac Surg 2020; 110:1605-1614. [PMID: 32251659 PMCID: PMC11040511 DOI: 10.1016/j.athoracsur.2020.02.064] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/05/2020] [Accepted: 02/26/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Functional tricuspid regurgitation due to annular and ventricular dilatation is increasingly recognized as a significant source of morbidity and mortality. To repair the annulus, surgeons implant one of many annuloplasty devices that differ in size, 3-dimensional (3D) shape, and stiffness. However, there have been no quantitative comparisons between various available devices. METHODS Three-dimensional scanning, micro-computed tomography imaging, analytical methods, and mechanical tests were used to compare 3 Edwards Lifesciences (Irvine, CA) and 3 Medtronic (Minneapolis, MN) annuloplasty devices of all available sizes. We measured in-plane metrics of maximum diameter, perimeter, area, height, as well as elevation and curvature profiles. Furthermore, we computed bending stiffness as well as the maximum and minimum axes of the bending stiffness. RESULTS Most annular prostheses differed little in their in-plane geometries but varied significantly in height. In-plane properties deviated significantly from measurements of healthy human tricuspid annuli. Height of the Edwards' MC3 and Medtronic's Contour 3D resembled healthy human tricuspid valve annuli, whereas the Edwards' Physio and Classic, and Medtronic's TriAd, did not. Additionally, the elevation profiles of the MC3 and Contour 3D and curvature profiles between all devices were consistent and matched those of healthy human annuli. The tested devices also differed in their bending stiffness, both in terms of absolute values and their maximum and minimum axes. CONCLUSIONS Contoured devices, such as Edwards' MC3 and Medtronic's Contour 3D, most accurately resembled the healthy human tricuspid annulus but differed significantly in bending stiffness. To what extent prosthesis properties and shape affect tricuspid valve function remains to be determined.
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Affiliation(s)
- Mrudang Mathur
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas
| | - Marcin Malinowski
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, Michigan; Department of Cardiac Surgery, Medical University of Silesia School of Medicine in Katowice, Katowice, Poland
| | - Tomasz A Timek
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, Michigan
| | - Manuel K Rausch
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas; Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX; Oden Institute for Computational Engineering and Science, The University of Texas at Austin, Austin, Texas.
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19
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Structural Responses of Integrated Parametric Aortic Valve in an Electro-Mechanical Full Heart Model. Ann Biomed Eng 2020; 49:441-454. [PMID: 32705423 DOI: 10.1007/s10439-020-02575-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 07/15/2020] [Indexed: 10/23/2022]
Abstract
The aortic valve (AV) is located between the left ventricle and the aorta and responsible for maintaining an outward unidirectional flow. Many AV hemodynamic and structural aspects of have been extensively studied, however, more sophisticated models are needed to better understand the AV biomechanical behavior. This study deals with integrating a new parametric AV structural model with the electro-mechanical Living Heart Human Model® (LHHM). The LHHM is a finite element model simulating human heart capable of realistic electro-mechanical simulations. Different geometric metrics of AV have been examined. New integrated structural AV model within the LHHM better predict local stresses during the cardiac cycle due to the realistic boundary condition derived from the LHHM. It was found that ellipticity index (EI), calculated as the ratio between the maximal (Max) and minimal (Min) aortic annulus (AA) diameters, well correlates with measured clinical data obtained from patients undergoing computed tomography (CT) while the annular perimeter (Perim) matches the same trend. This increases the confidence in the predicted kinematic behavior, leaflets coaptation, and the overall stresses. From the clinical aspect, the new proposed coupled and integrated AV modeling can serve as a platform for design and implementation of pre-transcatheter aortic valve replacement (TAVR) procedures.
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20
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Balmus M, Massing A, Hoffman J, Razavi R, Nordsletten DA. A partition of unity approach to fluid mechanics and fluid-structure interaction. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2020; 362:112842. [PMID: 34093912 PMCID: PMC7610902 DOI: 10.1016/j.cma.2020.112842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
For problems involving large deformations of thin structures, simulating fluid-structure interaction (FSI) remains a computationally expensive endeavour which continues to drive interest in the development of novel approaches. Overlapping domain techniques have been introduced as a way to combine the fluid-solid mesh conformity, seen in moving-mesh methods, without the need for mesh smoothing or re-meshing, which is a core characteristic of fixed mesh approaches. In this work, we introduce a novel overlapping domain method based on a partition of unity approach. Unified function spaces are defined as a weighted sum of fields given on two overlapping meshes. The method is shown to achieve optimal convergence rates and to be stable for steady-state Stokes, Navier-Stokes, and ALE Navier-Stokes problems. Finally, we present results for FSI in the case of 2D flow past an elastic beam simulation. These initial results point to the potential applicability of the method to a wide range of FSI applications, enabling boundary layer refinement and large deformations without the need for re-meshing or user-defined stabilization.
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Affiliation(s)
- Maximilian Balmus
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, King’s College London, King’s Health Partners, London SE1 7EH, United Kingdom
| | - André Massing
- Department of Mathematics and Mathematical Statistics, Umeå University, SE-90187 Umeå, Sweden
- Department of Mathematical Sciences, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Johan Hoffman
- Division of Computational Science and Technology, KTH Royal Institute of Technology, Sweden
| | - Reza Razavi
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, King’s College London, King’s Health Partners, London SE1 7EH, United Kingdom
| | - David A. Nordsletten
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, King’s College London, King’s Health Partners, London SE1 7EH, United Kingdom
- Department of Biomedical Engineering and Cardiac Surgery, University of Michigan, MI, USA
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21
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Guan D, Yao J, Luo X, Gao H. Effect of myofibre architecture on ventricular pump function by using a neonatal porcine heart model: from DT-MRI to rule-based methods. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191655. [PMID: 32431869 PMCID: PMC7211874 DOI: 10.1098/rsos.191655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/26/2020] [Indexed: 05/17/2023]
Abstract
Myofibre architecture is one of the essential components when constructing personalized cardiac models. In this study, we develop a neonatal porcine bi-ventricle model with three different myofibre architectures for the left ventricle (LV). The most realistic one is derived from ex vivo diffusion tensor magnetic resonance imaging, and other two simplifications are based on rule-based methods (RBM): one is regionally dependent by dividing the LV into 17 segments, each with different myofibre angles, and the other is more simplified by assigning a set of myofibre angles across the whole ventricle. Results from different myofibre architectures are compared in terms of cardiac pump function. We show that the model with the most realistic myofibre architecture can produce larger cardiac output, higher ejection fraction and larger apical twist compared with those of the rule-based models under the same pre/after-loads. Our results also reveal that when the cross-fibre contraction is included, the active stress seems to play a dual role: its sheet-normal component enhances the ventricular contraction while its sheet component does the opposite. We further show that by including non-symmetric fibre dispersion using a general structural tensor, even the most simplified rule-based myofibre model can achieve similar pump function as the most realistic one, and cross-fibre contraction components can be determined from this non-symmetric dispersion approach. Thus, our study highlights the importance of including myofibre dispersion in cardiac modelling if RBM are used, especially in personalized models.
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Affiliation(s)
- Debao Guan
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
| | - Jiang Yao
- Dassault Systemes, Johnston, RI, USA
| | - Xiaoyu Luo
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
| | - Hao Gao
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
- Author for correspondence: Hao Gao e-mail:
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22
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Shalaby N, Zemzemi N, Elkhodary K. Simulating the effect of sodium channel blockage on cardiac electromechanics. Proc Inst Mech Eng H 2019; 234:16-27. [PMID: 31625448 DOI: 10.1177/0954411919882514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is growing interest to better understand drug-induced cardiovascular complications and to predict undesirable side effects at as early a stage in the drug development process as possible. The purpose of this paper is to investigate computationally the influence of sodium ion channel blockage on cardiac electromechanics. To do so, we implement a myofiber orientation dependent passive stress model (Holzapfel-Ogden) in the multiphysics solver Chaste to simulate an imaged physiological model of the human ventricles. A dosage of a sodium channel blocker was then applied and its inhibitory effects on the electrical propagation across ventricles were modeled. We employ the Kerckhoffs active stress model to generate electrically excited contractile behavior of myofibers. Our predictions indicate that a delay in the electrical activation of ventricular tissue caused by the sodium channel blockage translates to a delay in the mechanical biomarkers that were investigated. Moreover, sodium channel blockage was found to increase left ventricular twist. A multiphysics computational framework from the cell level to the organ level was thus used to predict the effect of sodium channel blocking drugs on cardiac electromechanics.
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Affiliation(s)
- Noha Shalaby
- Mechanical Engineering Department, The American University in Cairo, New Cairo, Egypt
| | - Nejib Zemzemi
- INRIA Bordeaux Sud-Ouest, Carmen Group, Talence, France.,IHU-LIRYC, Pessac, France
| | - Khalil Elkhodary
- Mechanical Engineering Department, The American University in Cairo, New Cairo, Egypt
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23
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Du'o'ng MT, Holz D, Alkassar M, Dittrich S, Leyendecker S. Interaction of the Mechano-Electrical Feedback With Passive Mechanical Models on a 3D Rat Left Ventricle: A Computational Study. Front Physiol 2019; 10:1041. [PMID: 31607936 PMCID: PMC6769123 DOI: 10.3389/fphys.2019.01041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 07/30/2019] [Indexed: 01/28/2023] Open
Abstract
In this paper, we are investigating the interaction between different passive material models and the mechano-electrical feedback (MEF) in cardiac modeling. Various types of passive mechanical laws (nearly incompressible/compressible, polynomial/exponential-type, transversally isotropic/orthotropic material models) are integrated in a fully coupled electromechanical model in order to study their specific influence on the overall MEF behavior. Our computational model is based on a three-dimensional (3D) geometry of a healthy rat left ventricle reconstructed from magnetic resonance imaging (MRI). The electromechanically coupled problem is solved using a fully implicit finite element-based approach. The effects of different passive material models on the MEF are studied with the help of numerical examples. It turns out that there is a significant difference between the behavior of the MEF for compressible and incompressible material models. Numerical results for the incompressible models exhibit that a change in the electrophysiology can be observed such that the transmembrane potential (TP) is unable to reach the resting state in the repolarization phase, and this leads to non-zero relaxation deformations. The most significant and strongest effects of the MEF on the rat cardiac muscle response are observed for the exponential passive material law.
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Affiliation(s)
- Minh Tuấn Du'o'ng
- Chair of Applied Dynamics, University of Erlangen-Nuremberg, Erlangen, Germany
- School of Mechanical Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - David Holz
- Chair of Applied Dynamics, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Muhannad Alkassar
- Pediatric Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Sven Dittrich
- Pediatric Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Sigrid Leyendecker
- Chair of Applied Dynamics, University of Erlangen-Nuremberg, Erlangen, Germany
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24
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Dabiri Y, Van der Velden A, Sack KL, Choy JS, Kassab GS, Guccione JM. Prediction of Left Ventricular Mechanics Using Machine Learning. FRONTIERS IN PHYSICS 2019; 7:117. [PMID: 31903394 PMCID: PMC6941671 DOI: 10.3389/fphy.2019.00117] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The goal of this paper was to provide a real-time left ventricular (LV) mechanics simulator using machine learning (ML). Finite element (FE) simulations were conducted for the LV with different material properties to obtain a training set. A hyperelastic fiber-reinforced material model was used to describe the passive behavior of the myocardium during diastole. The active behavior of the heart resulting from myofiber contractions was added to the passive tissue during systole. The active and passive properties govern the LV constitutive equation. These mechanical properties were altered using optimal Latin hypercube design of experiments to obtain training FE models with varied active properties (volume and pressure predictions) and varied passive properties (stress predictions). For prediction of LV pressures, we used eXtreme Gradient Boosting (XGboost) and Cubist, and XGBoost was used for predictions of LV pressures, volumes as well as LV stresses. The LV pressure and volume results obtained from ML were similar to FE computations. The ML results could capture the shape of LV pressure as well as LV pressure-volume loops. The results predicted by Cubist were smoother than those from XGBoost. The mean absolute errors were as follows: XGBoost volume: 1.734 ± 0.584 ml, XGBoost pressure: 1.544 ± 0.298 mmHg, Cubist volume: 1.495 ± 0.260 ml, Cubist pressure: 1.623 ± 0.191 mmHg, myofiber stress: 0.334 ± 0.228 kPa, cross myofiber stress: 0.075 ± 0.024 kPa, and shear stress: 0.050 ± 0.032 kPa. The simulation results show ML can predict LV mechanics much faster than the FE method. The ML model can be used as a tool to predict LV behavior. Training of our ML model based on a large group of subjects can improve its predictability for real world applications.
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Affiliation(s)
- Yaghoub Dabiri
- California Medical Innovations Institute, San Diego, CA, United States
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | | | - Kevin L. Sack
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - Jenny S. Choy
- California Medical Innovations Institute, San Diego, CA, United States
| | - Ghassan S. Kassab
- California Medical Innovations Institute, San Diego, CA, United States
| | - Julius M. Guccione
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
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25
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Dabiri Y, Sack K, Rebelo N, Wang P, Wang Y, Choy J, Kassab GS, Guccione J. Method for Calibration of Left Ventricle Material Properties using 3D Echocardiography Endocardial Strains. J Biomech Eng 2019; 141:2738327. [PMID: 31294752 DOI: 10.1115/1.4044215] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Indexed: 12/14/2022]
Abstract
We sought to calibrate mechanical properties of left ventricle (LV) based on 3D speckle tracking echocardiographic imaging data recorded from 16 segments defined by American Heart Association (AHA). The in vivo data were used to create finite element (FE) LV and biventricular (BV) models. The orientation of the fibers in the LV model was rule-based, but diffusion tensor magnetic resonance imaging (DT-MRI) data were used for the fiber directions in the BV model. A nonlinear fiber-reinforced constitutive equation was used to describe the passive behavior of the myocardium, whereas the active tension was described by a model based on tissue contraction (Tmax). Isight was used for optimization, which used Abaqus as the forward solver (Simulia, Providence, USA). The calibration of passive properties based on the end diastolic pressure volume relation (ED PVR) curve resulted in relatively good agreement (mean error = -0.04 ml). The difference between experimental and computational strains decreased after segmental strain metrics, rather than global metrics, were used for calibration: for the LV model, the mean difference reduced from 0.129 to 0.046 (circumferential) and from 0.076 to 0.059 (longitudinal); for the BV model, the mean difference nearly did not change in the circumferential direction (0.061) but reduced in the longitudinal direction from 0.076 to 0.055. The calibration of mechanical properties for myocardium can be improved using segmental strain metrics. The importance of realistic fiber orientation and geometry for modeling of the LV was shown.
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Affiliation(s)
- Yaghoub Dabiri
- Department of Surgery, University of California San Francisco, San Francisco, California, USA; University of California San Francisco, San Francisco, California; California Medical Innovations Institute, San Diego, California, USA; Full Mailing Address: 11107 Roselle Street Suite 211, San Diego, CA 92121
| | - Kevin Sack
- Department of Surgery, University of California San Francisco, San Francisco, California, USA; Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa; Full Mailing Address: Rm 7.26 Anatomy Building, University of Cape Town Medical Campus, Anzio Rd, Cape Town, 7925, South Africa
| | - Nuno Rebelo
- Member of ASME Nuno Rebelo Associates LLC, Fremont, California, USA; Full Mailing Address: 46709 Rancho Higuera Rd, Fremont, CA 94539, USA
| | - Peter Wang
- Dassault Systemes Simulia Corp, 1301 Atwood Avenue, Suite 101W, Johnston, RI 02919, USA; Full Mailing Address: 3979 Freedom Circle, Suite 750, Santa Clara, CA 95054
| | - Yunjie Wang
- Thornton Tomasetti, Cupertino, California, USA; Full Mailing Address: 19200 Stevens Creek Blvd, Suite 100, Cupertino, CA 95014
| | - Jenny Choy
- California Medical Innovations Institute, San Diego, California, USA; Full Mailing Address: 11107 Roselle Street Suite 201, San Diego, CA 92121
| | - Ghassan S Kassab
- California Medical Innovations Institute, San Diego, California, USA; Full Mailing Address: 11107 Roselle Street Suite 211, San Diego, CA 92121
| | - Julius Guccione
- Department of Surgery, University of California San Francisco, San Francisco, California, USA; Full Mailing Address: 4150 Clement St , San Francisco, CA 94121
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26
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Vashistha R, Kumar P, Dangi AK, Sharma N, Chhabra D, Shukla P. Quest for cardiovascular interventions: precise modeling and 3D printing of heart valves. J Biol Eng 2019; 13:12. [PMID: 30774709 PMCID: PMC6366048 DOI: 10.1186/s13036-018-0132-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
Digitalization of health care practices is substantially manifesting itself as an effective tool to diagnose and rectify complex cardiovascular abnormalities. For cardiovascular abnormalities, precise non-invasive imaging interventions are being used to develop patient specific diagnosis and surgical planning. Concurrently, pre surgical 3D simulation and computational modeling are aiding in the effective surgery and understanding of valve biomechanics, respectively. Consequently, 3D printing of patient specific valves that can mimic the original one will become an effective outbreak for valvular problems. Printing of these patient-specific tissues or organ components is becoming a viable option owing to the advances in biomaterials and additive manufacturing techniques. These additive manufacturing techniques are receiving a full-fledged support from burgeoning field of computational fluid dynamics, digital image processing, artificial intelligence, and continuum mechanics during their optimization and implementation. Further, studies at cellular and molecular biomechanics have enriched our understanding of biomechanical factors resulting in valvular heart diseases. Hence, the knowledge generated can guide us during the design and synthesis of biomaterials to develop superior extra cellular matrix, mimicking materials that can be used as a bioink for 3D printing of organs and tissues. With this notion, we have reviewed current opportunities and challenges in the diagnosis and treatment of heart valve abnormalities through patient-specific valve design via tissue engineering and 3D bioprinting. These valves can replace diseased valves by preserving homogeneity and individuality of the patients.
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Affiliation(s)
- Rajat Vashistha
- Optimization and Mechatronics Laboratory, Department of Mechanical Engineering, University Institute of Engineering and Technology, Maharshi Dayanand University, Rohtak, Haryana India
| | - Prasoon Kumar
- Department of Medical Devices, National Institute of Pharmaceutical Education and Research Ahmadabad, Gandhinagar, Gujarat 382355 India
| | | | - Naveen Sharma
- Department of Cardiology, Shalby Hospitals, Jabalpur, India
| | - Deepak Chhabra
- Optimization and Mechatronics Laboratory, Department of Mechanical Engineering, University Institute of Engineering and Technology, Maharshi Dayanand University, Rohtak, Haryana India
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana 124001 India
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27
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Peirlinck M, Sack KL, De Backer P, Morais P, Segers P, Franz T, De Beule M. Kinematic boundary conditions substantially impact in silico ventricular function. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3151. [PMID: 30188608 DOI: 10.1002/cnm.3151] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/28/2018] [Accepted: 09/01/2018] [Indexed: 06/08/2023]
Abstract
Computational cardiac mechanical models, individualized to the patient, have the potential to elucidate the fundamentals of cardiac (patho-)physiology, enable non-invasive quantification of clinically significant metrics (eg, stiffness, active contraction, work), and anticipate the potential efficacy of therapeutic cardiovascular intervention. In a clinical setting, however, the available imaging resolution is often limited, which limits cardiac models to focus on the ventricles, without including the atria, valves, and proximal arteries and veins. In such models, the absence of surrounding structures needs to be accounted for by imposing realistic kinematic boundary conditions, which, for prognostic purposes, are preferably generic and thus non-image derived. Unfortunately, the literature on cardiac models shows no consistent approach to kinematically constrain the myocardium. The impact of different approaches (eg, fully constrained base, constrained epi-ring) on the predictive capacity of cardiac mechanical models has not been thoroughly studied. For that reason, this study first gives an overview of current approaches to kinematically constrain (bi) ventricular models. Next, we developed a patient-specific in silico biventricular model that compares well with literature and in vivo recorded strains. Alternative constraints were introduced to assess the influence of commonly used mechanical boundary conditions on both the predicted global functional behavior of the in-silico heart (cavity volumes, stroke volume, ejection fraction) and local strain distributions. Meaningful differences in global functioning were found between different kinematic anchoring strategies, which brought forward the importance of selecting appropriate boundary conditions for biventricular models that, in the near future, may inform clinical intervention. However, whilst statistically significant differences were also found in local strain distributions, these differences were minor and mostly confined to the region close to the applied boundary conditions.
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Affiliation(s)
- Mathias Peirlinck
- Biofluid, Tissue and Solid Mechanics for Medical Applications Lab (IBiTech, bioMMeda), Ghent University, Ghent, Belgium
| | - Kevin L Sack
- Department of Surgery, University of California at San Francisco, San Francisco, CA, USA
- Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, Observatory, South Africa
| | | | - Pedro Morais
- Lab on Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KULeuven-University of Leuven, Leuven, Belgium
| | - Patrick Segers
- Biofluid, Tissue and Solid Mechanics for Medical Applications Lab (IBiTech, bioMMeda), Ghent University, Ghent, Belgium
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, Observatory, South Africa
- Bioengineering Science Research Group, Engineering Sciences, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - Matthieu De Beule
- Biofluid, Tissue and Solid Mechanics for Medical Applications Lab (IBiTech, bioMMeda), Ghent University, Ghent, Belgium
- FEops nv, Ghent, Belgium
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Dabiri Y, Sack KL, Shaul S, Sengupta PP, Guccione JM. Relationship of Transmural Variations in Myofiber Contractility to Left Ventricular Ejection Fraction: Implications for Modeling Heart Failure Phenotype With Preserved Ejection Fraction. Front Physiol 2018; 9:1003. [PMID: 30197595 PMCID: PMC6117406 DOI: 10.3389/fphys.2018.01003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 07/09/2018] [Indexed: 12/13/2022] Open
Abstract
The pathophysiological mechanisms underlying preserved left ventricular (LV) ejection fraction (EF) in patients with heart failure and preserved ejection fraction (HFpEF) remain incompletely understood. We hypothesized that transmural variations in myofiber contractility with existence of subendocardial dysfunction and compensatory increased subepicardial contractility may underlie preservation of LVEF in patients with HFpEF. We quantified alterations in myocardial function in a mathematical model of the human LV that is based on the finite element method. The fiber-reinforced material formulation of the myocardium included passive and active properties. The passive material properties were determined such that the diastolic pressure-volume behavior of the LV was similar to that shown in published clinical studies of pressure-volume curves. To examine changes in active properties, we considered six scenarios: (1) normal properties throughout the LV wall; (2) decreased myocardial contractility in the subendocardium; (3) increased myocardial contractility in the subepicardium; (4) myocardial contractility decreased equally in all layers, (5) myocardial contractility decreased in the midmyocardium and subepicardium, (6) myocardial contractility decreased in the subepicardium. Our results indicate that decreased subendocardial contractility reduced LVEF from 53.2 to 40.5%. Increased contractility in the subepicardium recovered LVEF from 40.5 to 53.2%. Decreased contractility transmurally reduced LVEF and could not be recovered if subepicardial and midmyocardial contractility remained depressed. The computational results simulating the effects of transmural alterations in the ventricular tissue replicate the phenotypic patterns of LV dysfunction observed in clinical practice. In particular, data for LVEF, strain and displacement are consistent with previous clinical observations in patients with HFpEF, and substantiate the hypothesis that increased subepicardial contractility may compensate for subendocardial dysfunction and play a vital role in maintaining LVEF.
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Affiliation(s)
- Yaghoub Dabiri
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Kevin L Sack
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Semion Shaul
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Partho P Sengupta
- Section of Cardiology, West Virginia University Heart and Vascular Institute, West Virginia University, Morgantown, WV, United States
| | - Julius M Guccione
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
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29
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Rausch MK, Malinowski M, Meador WD, Wilton P, Khaghani A, Timek TA. The Effect of Acute Pulmonary Hypertension on Tricuspid Annular Height, Strain, and Curvature in Sheep. Cardiovasc Eng Technol 2018; 9:365-376. [DOI: 10.1007/s13239-018-0367-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/24/2018] [Indexed: 12/16/2022]
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30
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Sack KL, Aliotta E, Ennis DB, Choy JS, Kassab GS, Guccione JM, Franz T. Construction and Validation of Subject-Specific Biventricular Finite-Element Models of Healthy and Failing Swine Hearts From High-Resolution DT-MRI. Front Physiol 2018; 9:539. [PMID: 29896107 PMCID: PMC5986944 DOI: 10.3389/fphys.2018.00539] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 04/26/2018] [Indexed: 12/15/2022] Open
Abstract
Predictive computational modeling has revolutionized classical engineering disciplines and is in the process of transforming cardiovascular research. This is particularly relevant for investigating emergent therapies for heart failure, which remains a leading cause of death globally. The creation of subject-specific biventricular computational cardiac models has been a long-term endeavor within the biomedical engineering community. Using high resolution (0.3 × 0.3 × 0.8 mm) ex vivo data, we constructed a precise fully subject-specific biventricular finite-element model of healthy and failing swine hearts. Each model includes fully subject-specific geometries, myofiber architecture and, in the case of the failing heart, fibrotic tissue distribution. Passive and active material properties are prescribed using hyperelastic strain energy functions that define a nearly incompressible, orthotropic material capable of contractile function. These materials were calibrated using a sophisticated multistep approach to match orthotropic tri-axial shear data as well as subject-specific hemodynamic ventricular targets for pressure and volume to ensure realistic cardiac function. Each mechanically beating heart is coupled with a lumped-parameter representation of the circulatory system, allowing for a closed-loop definition of cardiovascular flow. The circulatory model incorporates unidirectional fluid exchanges driven by pressure gradients of the model, which in turn are driven by the mechanically beating heart. This creates a computationally meaningful representation of the dynamic beating of the heart coupled with the circulatory system. Each model was calibrated using subject-specific experimental data and compared with independent in vivo strain data obtained from echocardiography. Our methods produced highly detailed representations of swine hearts that function mechanically in a remarkably similar manner to the in vivo subject-specific strains on a global and regional comparison. The degree of subject-specificity included in the models represents a milestone for modeling efforts that captures realism of the whole heart. This study establishes a foundation for future computational studies that can apply these validated methods to advance cardiac mechanics research.
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Affiliation(s)
- Kevin L. Sack
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Eric Aliotta
- Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | - Daniel B. Ennis
- Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jenny S. Choy
- California Medical Innovations Institute, Inc., San Diego, CA, United States
| | - Ghassan S. Kassab
- California Medical Innovations Institute, Inc., San Diego, CA, United States
| | - Julius M. Guccione
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa
- Bioengineering Science Research Group, Engineering Sciences, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
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Sack KL, Dabiri Y, Franz T, Solomon SD, Burkhoff D, Guccione JM. Investigating the Role of Interventricular Interdependence in Development of Right Heart Dysfunction During LVAD Support: A Patient-Specific Methods-Based Approach. Front Physiol 2018; 9:520. [PMID: 29867563 PMCID: PMC5962934 DOI: 10.3389/fphys.2018.00520] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/23/2018] [Indexed: 02/01/2023] Open
Abstract
Predictive computation models offer the potential to uncover the mechanisms of treatments whose actions cannot be easily determined by experimental or imaging techniques. This is particularly relevant for investigating left ventricular mechanical assistance, a therapy for end-stage heart failure, which is increasingly used as more than just a bridge-to-transplant therapy. The high incidence of right ventricular failure following left ventricular assistance reflects an undesired consequence of treatment, which has been hypothesized to be related to the mechanical interdependence between the two ventricles. To investigate the implication of this interdependence specifically in the setting of left ventricular assistance device (LVAD) support, we introduce a patient-specific finite-element model of dilated chronic heart failure. The model geometry and material parameters were calibrated using patient-specific clinical data, producing a mechanical surrogate of the failing in vivo heart that models its dynamic strain and stress throughout the cardiac cycle. The model of the heart was coupled to lumped-parameter circulatory systems to simulate realistic ventricular loading conditions. Finally, the impact of ventricular assistance was investigated by incorporating a pump with pressure-flow characteristics of an LVAD (HeartMate II™ operating between 8 and 12 k RPM) in parallel to the left ventricle. This allowed us to investigate the mechanical impact of acute left ventricular assistance at multiple operating-speeds on right ventricular mechanics and septal wall motion. Our findings show that left ventricular assistance reduces myofiber stress in the left ventricle and, to a lesser extent, right ventricle free wall, while increasing leftward septal-shift with increased operating-speeds. These effects were achieved with secondary, potentially negative effects on the interventricular septum which showed that support from LVADs, introduces unnatural bending of the septum and with it, increased localized stress regions. Left ventricular assistance unloads the left ventricle significantly and shifts the right ventricular pressure-volume-loop toward larger volumes and higher pressures; a consequence of left-to-right ventricular interactions and a leftward septal shift. The methods and results described in the present study are a meaningful advancement of computational efforts to investigate heart-failure therapies in silico and illustrate the potential of computational models to aid understanding of complex mechanical and hemodynamic effects of new therapies.
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Affiliation(s)
- Kevin L Sack
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa.,Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Yaghoub Dabiri
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa.,Bioengineering Science Research Group, Engineering Sciences, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - Scott D Solomon
- Department of Medicine, Brigham and Women's Hospital, Boston, MA, United States
| | - Daniel Burkhoff
- Cardiovascular Research Foundation, New York, NY, United States
| | - Julius M Guccione
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States
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32
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Sack KL, Davies NH, Guccione JM, Franz T. Personalised computational cardiology: Patient-specific modelling in cardiac mechanics and biomaterial injection therapies for myocardial infarction. Heart Fail Rev 2018; 21:815-826. [PMID: 26833320 PMCID: PMC4969231 DOI: 10.1007/s10741-016-9528-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Predictive computational modelling in biomedical research offers the potential to integrate diverse data, uncover biological mechanisms that are not easily accessible through experimental methods and expose gaps in knowledge requiring further research. Recent developments in computing and diagnostic technologies have initiated the advancement of computational models in terms of complexity and specificity. Consequently, computational modelling can increasingly be utilised as enabling and complementing modality in the clinic—with medical decisions and interventions being personalised. Myocardial infarction and heart failure are amongst the leading causes of death globally despite optimal modern treatment. The development of novel MI therapies is challenging and may be greatly facilitated through predictive modelling. Here, we review the advances in patient-specific modelling of cardiac mechanics, distinguishing specificity in cardiac geometry, myofibre architecture and mechanical tissue properties. Thereafter, the focus narrows to the mechanics of the infarcted heart and treatment of myocardial infarction with particular attention on intramyocardial biomaterial delivery.
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Affiliation(s)
- Kevin L Sack
- Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Private Bag X3, 7935, Observatory, South Africa
| | - Neil H Davies
- Cardiovascular Research Unit, MRC IUCHRU, Chris Barnard Division of Cardiothoracic Surgery, University of Cape Town, Observatory, South Africa
| | - Julius M Guccione
- Department of Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Private Bag X3, 7935, Observatory, South Africa.
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33
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Xi C, Latnie C, Zhao X, Tan JL, Wall ST, Genet M, Zhong L, Lee LC. Patient-Specific Computational Analysis of Ventricular Mechanics in Pulmonary Arterial Hypertension. J Biomech Eng 2017; 138:2551745. [PMID: 27589906 DOI: 10.1115/1.4034559] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Indexed: 11/08/2022]
Abstract
Patient-specific biventricular computational models associated with a normal subject and a pulmonary arterial hypertension (PAH) patient were developed to investigate the disease effects on ventricular mechanics. These models were developed using geometry reconstructed from magnetic resonance (MR) images, and constitutive descriptors of passive and active mechanics in cardiac tissues. Model parameter values associated with ventricular mechanical properties and myofiber architecture were obtained by fitting the models with measured pressure-volume loops and circumferential strain calculated from MR images using a hyperelastic warping method. Results show that the peak right ventricle (RV) pressure was substantially higher in the PAH patient (65 mmHg versus 20 mmHg), who also has a significantly reduced ejection fraction (EF) in both ventricles (left ventricle (LV): 39% versus 66% and RV: 18% versus 64%). Peak systolic circumferential strain was comparatively lower in both the left ventricle (LV) and RV free wall (RVFW) of the PAH patient (LV: -6.8% versus -13.2% and RVFW: -2.1% versus -9.4%). Passive stiffness, contractility, and myofiber stress in the PAH patient were all found to be substantially increased in both ventricles, whereas septum wall in the PAH patient possessed a smaller curvature than that in the LV free wall. Simulations using the PAH model revealed an approximately linear relationship between the septum curvature and the transseptal pressure gradient at both early-diastole and end-systole. These findings suggest that PAH can induce LV remodeling, and septum curvature measurements may be useful in quantifying transseptal pressure gradient in PAH patients.
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Affiliation(s)
- Ce Xi
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824-1226
| | - Candace Latnie
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824-1226
| | - Xiaodan Zhao
- National Heart Center Singapore, Singapore, Singapore 169609
| | - Ju Le Tan
- National Heart Center Singapore, Singapore, Singapore 169609
| | | | - Martin Genet
- LMS, École Polytechnique, CNRS, Université Paris-Saclay; Inria, Université Paris-Saclay, Palaiseau 91128, France
| | - Liang Zhong
- National Heart Center Singapore, Singapore, Singapore 169609;Duke-NUS Medical School, Singapore, Singapore 169857
| | - Lik Chuan Lee
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824-1226 e-mail:
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34
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Engineering Analysis of Tricuspid Annular Dynamics in the Beating Ovine Heart. Ann Biomed Eng 2017; 46:443-451. [PMID: 29139013 DOI: 10.1007/s10439-017-1961-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/10/2017] [Indexed: 12/11/2022]
Abstract
Functional tricuspid regurgitation is a significant source of morbidity and mortality in the US. Furthermore, treatment of functional tricuspid regurgitation is suboptimal with significant recurrence rates, which may, at least in part, be due to our limited knowledge of the relationship between valvular shape and function. Here we study the dynamics of the healthy in vivo ovine tricuspid annulus to improve our understanding of normal annular deformations throughout the cardiac cycle. To this end, we determine both clinical as well as engineering metrics of in vivo annular dynamics based on sonomicrometry crystals surgically attached to the annulus. We confirm that the tricuspid annulus undergoes large dynamic changes in area, perimeter, height, and eccentricity throughout the cardiac cycle. This deformation may be described as asymmetric in-plane motion of the annulus with minor out-of-plane motion. In addition, we employ strain and curvature to provide mechanistic insight into the origin of this deformation. Specifically, we find that strain and curvature vary considerable across the annulus with highly localized minima and maxima resulting in aforementioned configurational changes throughout the cardiac cycle. It is our hope that these data provide valuable information for clinicians and engineers alike and ultimately help us improve treatment of functional tricuspid regurgitation.
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35
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Gao H, Qi N, Feng L, Ma X, Danton M, Berry C, Luo X. Modelling mitral valvular dynamics-current trend and future directions. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e2858. [PMID: 27935265 PMCID: PMC5697636 DOI: 10.1002/cnm.2858] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 09/30/2016] [Accepted: 11/26/2016] [Indexed: 05/19/2023]
Abstract
Dysfunction of mitral valve causes morbidity and premature mortality and remains a leading medical problem worldwide. Computational modelling aims to understand the biomechanics of human mitral valve and could lead to the development of new treatment, prevention and diagnosis of mitral valve diseases. Compared with the aortic valve, the mitral valve has been much less studied owing to its highly complex structure and strong interaction with the blood flow and the ventricles. However, the interest in mitral valve modelling is growing, and the sophistication level is increasing with the advanced development of computational technology and imaging tools. This review summarises the state-of-the-art modelling of the mitral valve, including static and dynamics models, models with fluid-structure interaction, and models with the left ventricle interaction. Challenges and future directions are also discussed.
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Affiliation(s)
- Hao Gao
- School of Mathematics and StatisticsUniversity of GlasgowUK
| | - Nan Qi
- School of Mathematics and StatisticsUniversity of GlasgowUK
| | - Liuyang Feng
- School of Mathematics and StatisticsUniversity of GlasgowUK
| | | | - Mark Danton
- Department of Cardiac SurgeryRoyal Hospital for ChildrenGlasgowUK
| | - Colin Berry
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowUK
| | - Xiaoyu Luo
- School of Mathematics and StatisticsUniversity of GlasgowUK
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36
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Pappalardo O, Sturla F, Onorati F, Puppini G, Selmi M, Luciani G, Faggian G, Redaelli A, Votta E. Mass-spring models for the simulation of mitral valve function: Looking for a trade-off between reliability and time-efficiency. Med Eng Phys 2017; 47:93-104. [DOI: 10.1016/j.medengphy.2017.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 06/23/2017] [Accepted: 07/03/2017] [Indexed: 11/27/2022]
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37
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Gao H, Feng L, Qi N, Berry C, Griffith BE, Luo X. A coupled mitral valve-left ventricle model with fluid-structure interaction. Med Eng Phys 2017; 47:128-136. [PMID: 28751011 PMCID: PMC6779302 DOI: 10.1016/j.medengphy.2017.06.042] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 06/13/2017] [Accepted: 06/24/2017] [Indexed: 12/16/2022]
Abstract
Understanding the interaction between the valves and walls of the heart is important in assessing and subsequently treating heart dysfunction. This study presents an integrated model of the mitral valve (MV) coupled to the left ventricle (LV), with the geometry derived from in vivo clinical magnetic resonance images. Numerical simulations using this coupled MV-LV model are developed using an immersed boundary/finite element method. The model incorporates detailed valvular features, left ventricular contraction, nonlinear soft tissue mechanics, and fluid-mediated interactions between the MV and LV wall. We use the model to simulate cardiac function from diastole to systole. Numerically predicted LV pump function agrees well with in vivo data of the imaged healthy volunteer, including the peak aortic flow rate, the systolic ejection duration, and the LV ejection fraction. In vivo MV dynamics are qualitatively captured. We further demonstrate that the diastolic filling pressure increases significantly with impaired myocardial active relaxation to maintain a normal cardiac output. This is consistent with clinical observations. The coupled model has the potential to advance our fundamental knowledge of mechanisms underlying MV-LV interaction, and help in risk stratification and optimisation of therapies for heart diseases.
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Affiliation(s)
- Hao Gao
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK.
| | - Liuyang Feng
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Nan Qi
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Colin Berry
- Institute of Cardiovascular and Medical Science, University of Glasgow, Glasgow, UK
| | - Boyce E Griffith
- Departments of Mathematics and Biomedical Engineering and McAllister Heart Institute, University of North Carolina, Chapel Hill, NC, USA
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
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38
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Rausch MK, Genet M, Humphrey JD. An augmented iterative method for identifying a stress-free reference configuration in image-based biomechanical modeling. J Biomech 2017; 58:227-231. [PMID: 28549603 DOI: 10.1016/j.jbiomech.2017.04.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 02/22/2017] [Accepted: 04/24/2017] [Indexed: 10/19/2022]
Abstract
Continued advances in computational power and methods have enabled image-based biomechanical modeling to become an important tool in basic science, diagnostic and therapeutic medicine, and medical device design. One of the many challenges of this approach, however, is identification of a stress-free reference configuration based on in vivo images of loaded and often prestrained or residually stressed soft tissues and organs. Fortunately, iterative methods have been proposed to solve this inverse problem, among them Sellier's method. This method is particularly appealing because it is easy to implement, convergences reasonably fast, and can be coupled to nearly any finite element package. By means of several practical examples, however, we demonstrate that in its original formulation Sellier's method is not optimally fast and may not converge for problems with large deformations. Fortunately, we can also show that a simple, inexpensive augmentation of Sellier's method based on Aitken's delta-squared process can not only ensure convergence but also significantly accelerate the method.
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Affiliation(s)
- Manuel K Rausch
- Department of Biomedical Engineering, Yale University, United States; Department of Aerospace Engineering & Engineering Mechanics, University of Texas at Austin, United States.
| | - Martin Genet
- LMS, École Polytechnique, CNRS, Université Paris-Saclay, France; Inria, Université Paris-Saclay, France
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, United States
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39
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Land S, Park-Holohan SJ, Smith NP, Dos Remedios CG, Kentish JC, Niederer SA. A model of cardiac contraction based on novel measurements of tension development in human cardiomyocytes. J Mol Cell Cardiol 2017; 106:68-83. [PMID: 28392437 DOI: 10.1016/j.yjmcc.2017.03.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/12/2017] [Accepted: 03/31/2017] [Indexed: 11/18/2022]
Abstract
Experimental data from human cardiac myocytes at body temperature is crucial for a quantitative understanding of clinically relevant cardiac function and development of whole-organ computational models. However, such experimental data is currently very limited. Specifically, important measurements to characterize changes in tension development in human cardiomyocytes that occur with perturbations in cell length are not available. To address this deficiency, in this study we present an experimental data set collected from skinned human cardiac myocytes, including the passive and viscoelastic properties of isolated myocytes, the steady-state force calcium relationship at different sarcomere lengths, and changes in tension following a rapid increase or decrease in length, and after constant velocity shortening. This data set is, to our knowledge, the first characterization of length and velocity-dependence of tension generation in human skinned cardiac myocytes at body temperature. We use this data to develop a computational model of contraction and passive viscoelasticity in human myocytes. Our model includes troponin C kinetics, tropomyosin kinetics, a three-state crossbridge model that accounts for the distortion of crossbridges, and the cellular viscoelastic response. Each component is parametrized using our experimental data collected in human cardiomyocytes at body temperature. Furthermore we are able to confirm that properties of length-dependent activation at 37°C are similar to other species, with a shift in calcium sensitivity and increase in maximum tension. We revise our model of tension generation in the skinned isolated myocyte to replicate reported tension traces generated in intact muscle during isometric tension, to provide a model of human tension generation for multi-scale simulations. This process requires changes to calcium sensitivity, cooperativity, and crossbridge transition rates. We apply this model within multi-scale simulations of biventricular cardiac function and further refine the parametrization within the whole organ context, based on obtaining a healthy ejection fraction. This process reveals that crossbridge cycling rates differ between skinned myocytes and intact myocytes.
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Affiliation(s)
- Sander Land
- Department of Biomedical Engineering, King's College London, UK.
| | - So-Jin Park-Holohan
- Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, UK
| | - Nicolas P Smith
- Department of Engineering Science, University of Auckland, New Zealand
| | | | - Jonathan C Kentish
- Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, UK
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40
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Rausch MK, Zöllner AM, Genet M, Baillargeon B, Bothe W, Kuhl E. A virtual sizing tool for mitral valve annuloplasty. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:10.1002/cnm.2788. [PMID: 27028496 PMCID: PMC5289896 DOI: 10.1002/cnm.2788] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/16/2016] [Accepted: 03/19/2016] [Indexed: 05/08/2023]
Abstract
Functional mitral regurgitation, a backward leakage of the mitral valve, is a result of left ventricular growth and mitral annular dilatation. Its gold standard treatment is mitral annuloplasty, the surgical reduction in mitral annular area through the implantation of annuloplasty rings. Recurrent regurgitation rates may, however, be as high as 30% and more. While the degree of annular downsizing has been linked to improved long-term outcomes, too aggressive downsizing increases the risk of ring dehiscences and significantly impairs repair durability. Here, we prototype a virtual sizing tool to quantify changes in annular dimensions, surgically induced tissue strains, mitral annular stretches, and suture forces in response to mitral annuloplasty. We create a computational model of dilated cardiomyopathy onto which we virtually implant annuloplasty rings of different sizes. Our simulations confirm the common intuition that smaller rings are more invasive to the surrounding tissue, induce higher strains, and require larger suture forces than larger rings: The total suture force was 2.2 N for a 24-mm ring, 1.9 N for a 28-mm ring, and 0.8 N for a 32-mm ring. Our model predicts the highest risk of dehiscence in the septal and postero-lateral annulus where suture forces are maximal. These regions co-localize with regional peaks in myocardial strain and annular stretch. Our study illustrates the potential of realistic predictive simulations in cardiac surgery to identify areas at risk for dehiscence, guide the selection of ring size and shape, rationalize the design of smart annuloplasty rings and, ultimately, improve long-term outcomes after surgical mitral annuloplasty. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Manuel K. Rausch
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
| | - Alexander M. Zöllner
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Martin Genet
- Laboratoire de Mécanique des Solides CNRS-UMR 7649, Ecole Polytechnique, 91128 Palaiseau, France
| | | | - Wolfgang Bothe
- University Heart Center Freiburg, 79106 Freiburg, Germany
| | - E. Kuhl
- Departments of Mechanical Engineering, Bioengineering and Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA
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Biglino G, Capelli C, Bruse J, Bosi GM, Taylor AM, Schievano S. Computational modelling for congenital heart disease: how far are we from clinical translation? Heart 2016; 103:98-103. [PMID: 27798056 PMCID: PMC5284484 DOI: 10.1136/heartjnl-2016-310423] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/26/2016] [Accepted: 09/29/2016] [Indexed: 12/17/2022] Open
Abstract
Computational models of congenital heart disease (CHD) have become increasingly sophisticated over the last 20 years. They can provide an insight into complex flow phenomena, allow for testing devices into patient-specific anatomies (pre-CHD or post-CHD repair) and generate predictive data. This has been applied to different CHD scenarios, including patients with single ventricle, tetralogy of Fallot, aortic coarctation and transposition of the great arteries. Patient-specific simulations have been shown to be informative for preprocedural planning in complex cases, allowing for virtual stent deployment. Novel techniques such as statistical shape modelling can further aid in the morphological assessment of CHD, risk stratification of patients and possible identification of new ‘shape biomarkers’. Cardiovascular statistical shape models can provide valuable insights into phenomena such as ventricular growth in tetralogy of Fallot, or morphological aortic arch differences in repaired coarctation. In a constant move towards more realistic simulations, models can also account for multiscale phenomena (eg, thrombus formation) and importantly include measures of uncertainty (ie, CIs around simulation results). While their potential to aid understanding of CHD, surgical/procedural decision-making and personalisation of treatments is undeniable, important elements are still lacking prior to clinical translation of computational models in the field of CHD, that is, large validation studies, cost-effectiveness evaluation and establishing possible improvements in patient outcomes.
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Affiliation(s)
- Giovanni Biglino
- Bristol Heart Institute, School of Clinical Sciences, University of Bristol, Bristol, UK.,Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Claudio Capelli
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Jan Bruse
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Giorgia M Bosi
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Andrew M Taylor
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Silvia Schievano
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
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Partial LVAD restores ventricular outputs and normalizes LV but not RV stress distributions in the acutely failing heart in silico. Int J Artif Organs 2016; 39:421-430. [PMID: 27646633 PMCID: PMC5067236 DOI: 10.5301/ijao.5000520] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2016] [Indexed: 12/15/2022]
Abstract
PURPOSE Heart failure is a worldwide epidemic that is unlikely to change as the population ages and life expectancy increases. We sought to detail significant recent improvements to the Dassault Systèmes Living Heart Model (LHM) and use the LHM to compute left ventricular (LV) and right ventricular (RV) myofiber stress distributions under the following 4 conditions: (1) normal cardiac function; (2) acute left heart failure (ALHF); (3) ALHF treated using an LV assist device (LVAD) flow rate of 2 L/min; and (4) ALHF treated using an LVAD flow rate of 4.5 L/min. METHODS AND RESULTS Incorporating improved systolic myocardial material properties in the LHM resulted in its ability to simulate the Frank-Starling law of the heart. We decreased myocardial contractility in the LV myocardium so that LV ejection fraction decreased from 56% to 28%. This caused mean LV end diastolic (ED) stress to increase to 508% of normal, mean LV end systolic (ES) stress to increase to 113% of normal, mean RV ED stress to decrease to 94% of normal and RV ES to increase to 570% of normal. When ALHF in the model was treated with an LVAD flow rate of 4.5 L/min, most stress results normalized. Mean LV ED stress became 85% of normal, mean LV ES stress became 109% of normal and mean RV ED stress became 95% of normal. However, mean RV ES stress improved less dramatically (to 342% of normal values). CONCLUSIONS These simulations strongly suggest that an LVAD is effective in normalizing LV stresses but not RV stresses that become elevated as a result of ALHF.
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