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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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Neelakantan S, Mendiola EA, Zambrano B, Vang A, Myers KJ, Zhang P, Choudhary G, Avazmohammadi R. Dissecting contributions of pulmonary arterial remodeling to right ventricular afterload in pulmonary hypertension. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.18.608471. [PMID: 39229168 PMCID: PMC11370336 DOI: 10.1101/2024.08.18.608471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Pulmonary hypertension (PH) is defined as an elevation in the right ventricle (RV) afterload, characterized by increased hemodynamic pressure in the main pulmonary artery (PA). Elevations in RV afterload increase RV wall stress, resulting in RV remodeling and potentially RV failure. From a biomechanical standpoint, the primary drivers for RV afterload elevations include increases in pulmonary vascular resistance (PVR) in the distal vasculature and decreases in vessel compliance in the proximal PA. However, the individual contributions of the various vascular remodeling events toward the progression of PA pressure elevations and altered vascular hemodynamics remain elusive. In this study, we used a subject-specific one-dimensional (1D) fluid-structure interaction (FSI) model to investigate the alteration of pulmonary hemodynamics in PH and to quantify the contributions of vascular stiffening and increased resistance towards increased main pulmonary artery (MPA) pressure. We used a combination of subject-specific hemodynamic measurements, ex-vivo mechanical testing of arterial tissue specimens, and ex-vivo X-ray micro-tomography imaging to develop the 1D-FSI model and dissect the contribution of PA remodeling events towards alterations in the MPA pressure waveform. Both the amplitude and pulsatility of the MPA pressure waveform were analyzed. Our results indicated that increased distal resistance has the greatest effect on the increase in maximum MPA pressure, while increased stiffness caused significant elevations in the characteristic impedance. The method presented in this study will serve as an essential step toward understanding the complex interplay between PA remodeling events that leads to the most severe adverse effect on RV dysfunction.
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Affiliation(s)
- Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Emilio A. Mendiola
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Byron Zambrano
- J. Mike Walker ‘66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
| | - Alexander Vang
- Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Kyle J. Myers
- Hagler Institute of Advanced Study, Texas A&M University, College Station, TX, USA
| | - Peng Zhang
- Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Gaurav Choudhary
- Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- J. Mike Walker ‘66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA
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LeBar K, Liu W, Chicco AJ, Wang Z. Role of Microtubule Network in the Passive Anisotropic Viscoelasticity of Healthy Right Ventricle. J Biomech Eng 2024; 146:071003. [PMID: 38329431 DOI: 10.1115/1.4064685] [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: 10/19/2023] [Accepted: 01/31/2024] [Indexed: 02/09/2024]
Abstract
Cardiomyocytes are viscoelastic and key determinants of right ventricle (RV) mechanics. Intracellularly, microtubules are found to impact the viscoelasticity of isolated cardiomyocytes or trabeculae; whether they contribute to the tissue-level viscoelasticity is unknown. Our goal was to reveal the role of the microtubule network in the passive anisotropic viscoelasticity of the healthy RV. Equibiaxial stress relaxation tests were conducted in healthy RV free wall (RVFW) under early (6%) and end (15%) diastolic strain levels, and at sub- and physiological stretch rates. The viscoelasticity was assessed at baseline and after the removal of microtubule network. Furthermore, a quasi-linear viscoelastic (QLV) model was applied to delineate the contribution of microtubules to the relaxation behavior of RVFW. After removing the microtubule network, RVFW elasticity and viscosity were reduced at the early diastolic strain level and in both directions. The reduction in elasticity was stronger in the longitudinal direction, whereas the degree of changes in viscosity were equivalent between directions. There was insignificant change in RVFW viscoelasticity at late diastolic strain level. Finally, the modeling showed that the tissue's relaxation strength was reduced by the removal of the microtubule network, but the change was present only at a later time scale. These new findings suggest a critical role of cytoskeleton filaments in RVFW passive mechanics in physiological conditions.
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Affiliation(s)
- Kristen LeBar
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523
| | - Wenqiang Liu
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523; Stanford Cardiovascular Institute, Stanford University, Stanford, CA 80523
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
| | - Zhijie Wang
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523; School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523
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Neelakantan S, Vang A, Mehdi RR, Phelan H, Nicely P, Imran T, Zhang P, Choudhary G, Avazmohammadi R. Right ventricular stiffening and anisotropy alterations in pulmonary hypertension: Mechanisms and relations to function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.24.592212. [PMID: 38854032 PMCID: PMC11160581 DOI: 10.1101/2024.05.24.592212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Aims Pulmonary hypertension (PH) results in an increase in RV afterload, leading to RV dysfunction and failure. The mechanisms underlying maladaptive RV remodeling are poorly understood. In this study, we investigated the multiscale and mechanistic nature of RV free wall (RVFW) biomechanical remodeling and its correlations with RV function adaptations. Methods and Results Mild and severe models of PH, consisting of hypoxia (Hx) model in Sprague-Dawley (SD) rats (n=6 each, Control and PH) and Sugen-hypoxia (SuHx) model in Fischer (CDF) rats (n=6 each, Control and PH), were used. Organ-level function and tissue-level stiffness and microstructure were quantified through in-vivo and ex-vivo measures, respectively. Multiscale analysis was used to determine the association between fiber-level remodeling, tissue-level stiffening, and organ-level dysfunction. Animal models with different PH severity provided a wide range of RVFW stiffening and anisotropy alterations in PH. Decreased RV-pulmonary artery (PA) coupling correlated strongly with stiffening but showed a weaker association with the loss of RVFW anisotropy. Machine learning classification identified the range of adaptive and maladaptive RVFW stiffening. Multiscale modeling revealed that increased collagen fiber tautness was a key remodeling mechanism that differentiated severe from mild stiffening. Myofiber orientation analysis indicated a shift away from the predominantly circumferential fibers observed in healthy RVFW specimens, leading to a significant loss of tissue anisotropy. Conclusion Multiscale biomechanical analysis indicated that although hypertrophy and fibrosis occur in both mild and severe PH, certain fiber-level remodeling events, including increased tautness in the newly deposited collagen fibers and significant reorientations of myofibers, contributed to excessive biomechanical maladaptation of the RVFW leading to severe RV-PA uncoupling. Collagen fiber remodeling and the loss of tissue anisotropy can provide an improved understanding of the transition from adaptive to maladaptive remodeling. Translational perspective Right ventricular (RV) failure is a leading cause of mortality in patients with pulmonary hypertension (PH). RV diastolic and systolic impairments are evident in PH patients. Stiffening of the RV wall tissue and changes in the wall anisotropy are expected to be major contributors to both impairments. Global assessments of the RV function remain inadequate in identifying patients with maladaptive RV wall remodeling primarily due to their confounded and weak representation of RV fiber and tissue remodeling events. This study provides novel insights into the underlying mechanisms of RV biomechanical remodeling and identifies the adaptive-to-maladaptive transition across the RV biomechanics-function spectrum. Our analysis dissecting the contribution of different RV wall remodeling events to RV dysfunction determines the most adverse fiber-level remodeling to RV dysfunction as new therapeutic targets to curtail RV maladaptation and, in turn, RV failure in PH.
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Odeigah OO, Kwan ED, Garcia KM, Finsberg H, Valdez-Jasso D, Sundnes J. A computational study of right ventricular mechanics in a rat model of pulmonary arterial hypertension. Front Physiol 2024; 15:1360389. [PMID: 38529483 PMCID: PMC10961401 DOI: 10.3389/fphys.2024.1360389] [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: 12/22/2023] [Accepted: 02/23/2024] [Indexed: 03/27/2024] Open
Abstract
Pulmonary arterial hypertension (PAH) presents a significant challenge to right ventricular (RV) function due to progressive pressure overload, necessitating adaptive remodeling in the form of increased wall thickness, enhanced myocardial contractility and stiffness to maintain cardiac performance. However, the impact of these remodeling mechanisms on RV mechanics in not clearly understood. In addition, there is a lack of quantitative understanding of how each mechanism individually influences RV mechanics. Utilizing experimental data from a rat model of PAH at three distinct time points, we developed biventricular finite element models to investigate how RV stress and strain evolved with PAH progression. The finite element models were fitted to hemodynamic and morphological data to represent different disease stages and used to analyze the impact of RV remodeling as well as the altered RV pressure. Furthermore, we performed a number of theoretical simulation studies with different combinations of morphological and physiological remodeling, to assess and quantify their individual impact on overall RV load and function. Our findings revealed a substantial 4-fold increase in RV stiffness and a transient 2-fold rise in contractility, which returned to baseline by week 12. These changes in RV material properties in addition to the 2-fold increase in wall thickness significantly mitigated the increase in wall stress and strain caused by the progressive increase in RV afterload. Despite the PAH-induced cases showing increased wall stress and strain at end-diastole and end-systole compared to the control, our simulations suggest that without the observed remodeling mechanisms, the increase in stress and strain would have been much more pronounced. Our model analysis also indicated that while changes in the RV's material properties-particularly increased RV stiffness - have a notable effect on its mechanics, the primary compensatory factor limiting the stress and strain increase in the early stages of PAH was the significant increase in wall thickness. These findings underscore the importance of RV remodeling in managing the mechanical burden on the right ventricle due to pressure overload.
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Affiliation(s)
| | - Ethan D. Kwan
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Kristen M. Garcia
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | | | - Daniela Valdez-Jasso
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
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Roth K, Liu W, LeBar K, Ahern M, Wang Z. Establishment of a Biaxial Testing System for Characterization of Right Ventricle Viscoelasticity Under Physiological Loadings. Cardiovasc Eng Technol 2024:10.1007/s13239-024-00722-5. [PMID: 38468114 DOI: 10.1007/s13239-024-00722-5] [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: 03/10/2022] [Accepted: 02/19/2024] [Indexed: 03/13/2024]
Abstract
PURPOSE Prior studies have indicated an impact of cardiac muscle viscoelasticity on systolic and diastolic functions. However, the studies of ventricular free wall viscoelasticity, particularly for that of right ventricles (RV), are limited. Moreover, investigations on ventricular passive viscoelasticity have been restricted to large animals and there is a lack of data on rodent species. To fill this knowledge gap, this study aims to develop a biaxial tester that induces high-speed physiological deformations to characterize the passive viscoelasticity of rat RVs. METHODS The biaxial testing system was fabricated so that planar deformation of rat ventricle tissues at physiological strain rates was possible. The testing system was validated using isotropic polydimethylsiloxane (PDMS) sheets. Next, viscoelastic measurements were performed in healthy rat RV free walls by equibiaxial cyclic sinusoidal loadings and stress relaxation. RESULTS The biaxial tester's consistency, accuracy, and stability was confirmed from the PDMS samples measurements. Moreover, significant viscoelastic alterations of the RV were found between sub-physiological (0.1 Hz) and physiological frequencies (1-8 Hz). From hysteresis loop analysis, we found as the frequency increased, the elasticity and viscosity were increased in both directions. Interestingly, the ratio of storage energy to dissipated energy (Wd/Ws) remained constant at 0.1-5 Hz. We did not observe marked differences in healthy RV viscoelasticity between longitudinal and circumferential directions. CONCLUSION This work provides a new experimental tool to quantify the passive, biaxial viscoelasticity of ventricle free walls in both small and large animals. The dynamic mechanical tests showed frequency-dependent elastic and viscous behaviors of healthy rat RVs. But the ratio of dissipated energy to stored energy was maintained between frequencies. These findings offer novel baseline information on the passive viscoelasticity of healthy RVs in adult rats.
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Affiliation(s)
- Kellan Roth
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Wenqiang Liu
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Kristen LeBar
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Matt Ahern
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Zhijie Wang
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA.
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA.
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Guan D, Tian L, Li W, Gao H. Using LDDMM and a kinematic cardiac growth model to quantify growth and remodelling in rat hearts under PAH. Comput Biol Med 2024; 171:108218. [PMID: 38428098 DOI: 10.1016/j.compbiomed.2024.108218] [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: 11/12/2023] [Revised: 01/20/2024] [Accepted: 02/25/2024] [Indexed: 03/03/2024]
Abstract
Pulmonary arterial hypertension (PAH) is a rapidly progressive and fatal disease, with right ventricular failure being the primary cause of death in patients with PAH. This study aims to determine the mechanical stimuli that may initiate heart growth and remodelling (G&R). To achieve this, two bi-ventricular models were constructed: one for a control rat heart and another for a rat heart with PAH. The growth of the diseased heart was estimated by warping it to the control heart using an improved large deformation diffeomorphic metric mapping (LDDMM) framework. Correlation analysis was then performed between mechanical cues (stress and strain) and growth tensors, which revealed that principal strains may serve as a triggering stimulus for myocardial growth and remodelling under PAH. The growth tensors, estimated from in vivo images, could explain 84.3% of the observed geometrical changes in the diseased heart with PAH by using a kinematic cardiac growth model. Our approach has the potential to quantify G&R using sparse in vivo images and to provide insights into the underlying mechanism of triggering right heart failure from a biomechanical perspective.
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Affiliation(s)
- Debao Guan
- School of Control Science and Engineering, Shandong University, China; School of Mathematics and Statistics, University of Glasgow, UK
| | - Lian Tian
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, UK
| | - Wei Li
- School of Control Science and Engineering, Shandong University, China
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, UK.
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Mendiola EA, Neelakantan S, Xiang Q, Xia S, Zhang J, Serpooshan V, Vanderslice P, Avazmohammadi R. An image-driven micromechanical approach to characterize multiscale remodeling in infarcted myocardium. Acta Biomater 2024; 173:109-122. [PMID: 37925122 PMCID: PMC10924194 DOI: 10.1016/j.actbio.2023.10.027] [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: 05/11/2023] [Revised: 10/19/2023] [Accepted: 10/24/2023] [Indexed: 11/06/2023]
Abstract
Myocardial infarction (MI) is accompanied by the formation of a fibrotic scar in the left ventricle (LV) and initiates significant alterations in the architecture and constituents of the LV free wall (LVFW). Previous studies have shown that LV adaptation is highly individual, indicating that the identification of remodeling mechanisms post-MI demands a fully subject-specific approach that can integrate a host of structural alterations at the fiber-level to changes in bulk biomechanical adaptation at the tissue-level. We present an image-driven micromechanical approach to characterize remodeling, assimilating new biaxial mechanical data, histological studies, and digital image correlation data within an in-silico framework to elucidate the fiber-level remodeling mechanisms that drive tissue-level adaptation for each subject. We found that a progressively diffused collagen fiber structure combined with similarly disorganized myofiber architecture in the healthy region leads to the loss of LVFW anisotropy post-MI, offering an important tissue-level hallmark for LV maladaptation. In contrast, our results suggest that reductions in collagen undulation are an adaptive mechanism competing against LVFW thinning. Additionally, we show that the inclusion of subject-specific geometry when modeling myocardial tissue is essential for accurate prediction of tissue kinematics. Our approach serves as an essential step toward identifying fiber-level remodeling indices that govern the transition of MI to systolic heart failure. These indices complement the traditional, organ-level measures of LV anatomy and function that often fall short of early prognostication of heart failure in MI. In addition, our approach offers an integrated methodology to advance the design of personalized interventions, such as hydrogel injection, to reinforce and suppress native adaptive and maladaptive mechanisms, respectively, to prevent the transition of MI to heart failure. STATEMENT OF SIGNIFICANCE: Biomechanical and architectural adaptation of the LVFW remains a central, yet overlooked, remodeling process post-MI. Our study indicates the biomechanical adaptation of the LVFW post-MI is highly individual and driven by altered fiber network architecture and collective changes in collagen fiber content, undulation, and stiffness. Our findings demonstrate the possibility of using cardiac strains to infer such fiber-level remodeling events through in-silico modeling, paving the way for in-vivo characterization of multiscale biomechanical indices in humans. Such indices will complement the traditional, organ-level measures of LV anatomy and function that often fall short of early prognostication of heart failure in MI.
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Affiliation(s)
- Emilio A Mendiola
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Qian Xiang
- Department of Molecular Cardiology, Texas Heart Institute, Houston, Texas, USA
| | - Shuda Xia
- Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Vahid Serpooshan
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine and Georgia Institute of Technology, Atlanta, GA, United States; Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States; Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Peter Vanderslice
- Department of Molecular Cardiology, Texas Heart Institute, Houston, Texas, USA.
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA; J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA; Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA.
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Kundu P, Schäfer M, Le L, Thomas T, Jone PN, Hunter KS. Three-Dimensional, Right Ventricular Surface Strain Computation From Three-Dimensional Echocardiographic Images From Patients With Pediatric Pulmonary Hypertension. J Biomech Eng 2023; 145:111011. [PMID: 37542708 DOI: 10.1115/1.4063121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 07/17/2023] [Indexed: 08/07/2023]
Abstract
Right Ventricular (RV) dysfunction is routinely assessed with echocardiographic-derived global longitudinal strain (GLS). GLS is measured from a two-dimensional echo image and is increasingly accepted as a means for assessing RV function. However, any two-dimensional (2D) analysis cannot visualize the asymmetrical deformation of the RV nor visualize strain over the entire RV surface. We believe three-dimensional surface (3DS) strain, obtained from 3D echo will better evaluate myocardial mechanics. Components of 3DS strain (longitudinal, LS; circumferential, CS; longitudinal-circumferential shear, ɣCL; principal strains PSMax and PSMin; max shear, ɣMax; and principal angle θMax) were computed from RV surface meshes obtained with 3D echo from 50 children with associated pulmonary arterial hypertension (PAH), 43 children with idiopathic PAH, and 50 healthy children by computing strains from a discretized displacement field. All 3DS freewall (FW) normal strain (LS, CS, PSMax, and PSMin) showed significant decline at end-systole in PH groups (p < 0.0001 for all), as did FW-ɣMax (p = 0.0012). FW-θMax also changed in disease (p < 0.0001). Limits of agreement analysis suggest that 3DS LS, PSMax, and PSMin are related to GLS. 3DS strains showed significant heterogeneity over the 3D surface of the RV. Components of 3DS strain agree with existing clinical strain measures, well classify normal -versus- PAH subjects, and suggest that strains change direction on the myocardial surface due to disease. This last finding is similar to that of myocardial fiber realignment in disease, but further work is needed to establish true associations.
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Affiliation(s)
- Priyamvada Kundu
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, 12705 E. Montview Ave., Suite 100, Aurora, CO 80045-7109
| | - Michal Schäfer
- Heart Institute, Children's Hospital Colorado, University of Colorado Anschutz Medical Campus, 13123 E 16th Ave, Aurora, CO 80045
| | - Lisa Le
- Heart Institute, Children's Hospital Colorado, University of Colorado Anschutz Medical Campus, 13123 E 16th Ave, Aurora, CO 80045
| | - Thomas Thomas
- Heart Institute, Children's Hospital Colorado, University of Colorado Anschutz Medical Campus, 13123 E 16th Ave, Aurora, CO 80045
| | - Pei-Ni Jone
- Ann & Robert H. Lurie Children's Hospital of Chicago, 225 East Chicago Avenue, Chicago, IL 60611-2605
| | - Kendall S Hunter
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, 12705 E. Montview Ave., Suite 100, Aurora, CO 80045-7109
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Kakaletsis S, Malinowski M, Snider JC, Mathur M, Sugerman GP, Luci JJ, Kostelnik CJ, Jazwiec T, Bersi MR, Timek TA, Rausch MK. Untangling the mechanisms of pulmonary arterial hypertension-induced right ventricular stiffening in a large animal model. Acta Biomater 2023; 171:155-165. [PMID: 37797706 PMCID: PMC11048731 DOI: 10.1016/j.actbio.2023.09.043] [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: 05/04/2023] [Revised: 09/20/2023] [Accepted: 09/26/2023] [Indexed: 10/07/2023]
Abstract
Pulmonary hypertension (PHT) is a devastating disease with low survival rates. In PHT, chronic pressure overload leads to right ventricle (RV) stiffening; thus, impeding diastolic filling. Multiple mechanisms may contribute to RV stiffening, including wall thickening, microstructural disorganization, and myocardial stiffening. The relative importance of each mechanism is unclear. Our objective is to use a large animal model to untangle these mechanisms. Thus, we induced pulmonary arterial hypertension (PAH) in sheep via pulmonary artery banding. After eight weeks, the hearts underwent anatomic and diffusion tensor MRI to characterize wall thickening and microstructural disorganization. Additionally, myocardial samples underwent histological and gene expression analyses to quantify compositional changes and mechanical testing to quantify myocardial stiffening. Finally, we used finite element modeling to disentangle the relative importance of each stiffening mechanism. We found that the RVs of PAH animals thickened most at the base and the free wall and that PAH induced excessive collagen synthesis, increased cardiomyocyte cross-sectional area, and led to microstructural disorganization, consistent with increased expression of fibrotic genes. We also found that the myocardium itself stiffened significantly. Importantly, myocardial stiffening correlated significantly with collagen synthesis. Finally, our computational models predicted that myocardial stiffness contributes to RV stiffening significantly more than other mechanisms. Thus, myocardial stiffening may be the most important predictor for PAH progression. Given the correlation between myocardial stiffness and collagen synthesis, collagen-sensitive imaging modalities may be useful for estimating myocardial stiffness and predicting PAH outcomes. STATEMENT OF SIGNIFICANCE: Ventricular stiffening is a significant contributor to pulmonary hypertension-induced right heart failure. However, the mechanisms that lead to ventricular stiffening are not fully understood. The novelty of our work lies in answering this question through the use of a large animal model in combination with spatially- and directionally sensitive experimental techniques. We find that myocardial stiffness is the primary mechanism that leads to ventricular stiffening. Clinically, this knowledge may be used to improve diagnostic, prognostic, and therapeutic strategies for patients with pulmonary hypertension.
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Affiliation(s)
- Sotirios Kakaletsis
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX, USA
| | - Marcin Malinowski
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA; Department of Cardiac Surgery, Medical University of Silesia, Katowice, Poland
| | - J Caleb Snider
- Department of Mechanical Engineering & Materials Science, Washington University at St. Louis, St. Louis, MO, USA
| | - Mrudang Mathur
- Department of Mechanical Engineering, The University of Texas at Austin, TX, USA
| | - Gabriella P Sugerman
- Department of Biomedical Engineering, The University of Texas at Austin, TX, USA
| | - Jeffrey J Luci
- Center for Advanced Human Brain Imaging Research, Rutgers University, Piscataway, NJ, USA; Scully Neuroimaging Center, Princeton University, Princeton, NJ, USA
| | - Colton J Kostelnik
- Department of Mechanical Engineering, The University of Texas at Austin, TX, USA; Department of Biomedical Engineering, The University of Texas at Austin, TX, USA
| | - Tomasz Jazwiec
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA; Department of Cardiac, Vascular and Endovascular Surgery and Transplantology, Medical University of Silesia in Katowice, Silesian Centre for Heart Diseases, Zabrze, Poland
| | - Matthew R Bersi
- Department of Mechanical Engineering & Materials Science, Washington University at St. Louis, St. Louis, MO, USA
| | - Tomasz A Timek
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, USA
| | - Manuel K Rausch
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX, USA; Department of Mechanical Engineering, The University of Texas at Austin, TX, USA; Department of Biomedical Engineering, The University of Texas at Austin, TX, USA.
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11
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Kheyfets VO, Kumar S, Heerdt PM, Ichimura K, Brown RD, Lucero M, Essafri I, Williams S, Stenmark KR, Spiekerkoetter E. Characterizing the Spatiotemporal Transcriptomic Response of the Right Ventricle to Acute Pressure Overload. Int J Mol Sci 2023; 24:9746. [PMID: 37298696 PMCID: PMC10253685 DOI: 10.3390/ijms24119746] [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: 03/24/2023] [Revised: 05/22/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
This study analyzed microarray data of right ventricular (RV) tissue from rats exposed to pulmonary embolism to understand the initial dynamic transcriptional response to mechanical stress and compare it with experimental pulmonary hypertension (PH) models. The dataset included samples harvested from 55 rats at 11 different time points or RV locations. We performed principal component analysis (PCA) to explore clusters based on spatiotemporal gene expression. Relevant pathways were identified from fast gene set enrichment analysis using PCA coefficients. The RV transcriptomic signature was measured over several time points, ranging from hours to weeks after an acute increase in mechanical stress, and was found to be highly dependent on the severity of the initial insult. Pathways enriched in the RV outflow tracts of rats at 6 weeks after severe PE share many commonalities with experimental PH models, but the transcriptomic signature at the RV apex resembles control tissue. The severity of the initial pressure overload determines the trajectory of the transcriptomic response independent of the final afterload, but this depends on the location where the tissue is biopsied. Chronic RV pressure overload due to PH appears to progress toward similar transcriptomic endpoints.
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Affiliation(s)
- Vitaly O. Kheyfets
- Paediatric Critical Care Medicine, Developmental Lung Biology and CVP Research Laboratories, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Sushil Kumar
- Paediatric Critical Care Medicine, Developmental Lung Biology and CVP Research Laboratories, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Paul M. Heerdt
- Department of Anaesthesiology, Applied Hemodynamic, Yale School of Medicine, New Haven, CT 06510, USA
| | - Kenzo Ichimura
- Vera Moulton Wall Center for Pulmonary Vascular Disease, Stanford University, Stanford, CA 94305, USA
- Division of Pulmonary, Allergy and Critical Care Medicine, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - R. Dale Brown
- Paediatric Critical Care Medicine, Developmental Lung Biology and CVP Research Laboratories, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Melissa Lucero
- Paediatric Critical Care Medicine, Developmental Lung Biology and CVP Research Laboratories, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Ilham Essafri
- Paediatric Critical Care Medicine, Developmental Lung Biology and CVP Research Laboratories, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Sarah Williams
- Queensland Facility for Advanced Bioinformatics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kurt R. Stenmark
- Paediatric Critical Care Medicine, Developmental Lung Biology and CVP Research Laboratories, School of Medicine, University of Colorado, Aurora, CO 80045, USA
| | - Edda Spiekerkoetter
- Vera Moulton Wall Center for Pulmonary Vascular Disease, Stanford University, Stanford, CA 94305, USA
- Division of Pulmonary, Allergy and Critical Care Medicine, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA
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12
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Li DS, Mendiola EA, Avazmohammadi R, Sachse FB, Sacks MS. A multi-scale computational model for the passive mechanical behavior of right ventricular myocardium. J Mech Behav Biomed Mater 2023; 142:105788. [PMID: 37060716 PMCID: PMC10357348 DOI: 10.1016/j.jmbbm.2023.105788] [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: 07/23/2022] [Revised: 01/13/2023] [Accepted: 03/16/2023] [Indexed: 03/31/2023]
Abstract
We have previously demonstrated the importance of myofiber-collagen mechanical interactions in modeling the passive mechanical behavior of right ventricle free wall (RVFW) myocardium. To gain deeper insights into these coupling mechanisms, we developed a high-fidelity, micro-anatomically realistic 3D finite element model of right ventricle free wall (RVFW) myocardium by combining high-resolution imaging and supercomputer-based simulations. We first developed a representative tissue element (RTE) model at the sub-tissue scale by specializing the hyperelastic anisotropic structurally-based constitutive relations for myofibers and ECM collagen, and equi-biaxial and non-equibiaxial loading conditions were simulated using the open-source software FEniCS to compute the effective stress-strain response of the RTE. To estimate the model parameters of the RTE model, we first fitted a 'top-down' biaxial stress-strain behavior with our previous structurally based (tissue-scale) model, informed by the measured myofiber and collagen fiber composition and orientation distributions. Next, we employed a multi-scale approach to determine the tissue-level (5 x 5 x 0.7 mm specimen size) RVFW biaxial behavior via 'bottom-up' homogenization of the fitted RTE model, recapitulating the histologically measured myofiber and collagen orientation to the biaxial mechanical data. Our homogenization approach successfully reproduced the tissue-level mechanical behavior of our previous studies in all biaxial deformation modes, suggesting that the 3D micro-anatomical arrangement of myofibers and ECM collagen is indeed a primary mechanism driving myofiber-collagen interactions.
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Affiliation(s)
- David S Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Emilio A Mendiola
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Reza Avazmohammadi
- Computational Cardiovascular Bioengineering Lab, Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Frank B Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
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13
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Usman M, Mendiola EA, Mukherjee T, Mehdi RR, Ohayon J, Alluri PG, Sadayappan S, Choudhary G, Avazmohammadi R. On the possibility of estimating myocardial fiber architecture from cardiac strains. FUNCTIONAL IMAGING AND MODELING OF THE HEART : ... INTERNATIONAL WORKSHOP, FIMH ..., PROCEEDINGS. FIMH 2023; 13958:74-83. [PMID: 37671365 PMCID: PMC10478796 DOI: 10.1007/978-3-031-35302-4_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
The myocardium is composed of a complex network of contractile myofibers that are organized in such a way as to produce efficient contraction and relaxation of the heart. The myofiber architecture in the myocardium is a key determinant of cardiac motion and the global or organ-level function of the heart. Reports of architectural remodeling in cardiac diseases, such as pulmonary hypertension and myocardial infarction, potentially contributing to cardiac dysfunction call for the inclusion of an architectural marker for an improved assessment of cardiac function. However, the in-vivo quantification of three-dimensional myo-architecture has proven challenging. In this work, we examine the sensitivity of cardiac strains to varying myofiber orientation using a multiscale finite-element model of the LV. Additionally, we present an inverse modeling approach to predict the myocardium fiber structure from cardiac strains. Our results indicate a strong correlation between fiber orientation and LV kinematics, corroborating that the fiber structure is a principal determinant of LV contractile behavior. Our inverse model was capable of accurately predicting the myocardial fiber range and regional fiber angles from strain measures. A concrete understanding of the link between LV myofiber structure and motion, and the development of non-invasive and feasible means of characterizing the myocardium architecture is expected to lead to advanced LV functional metrics and improved prognostic assessment of structural heart disease.
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Affiliation(s)
- Muhammad Usman
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Emilio A Mendiola
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Tanmay Mukherjee
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Rana Raza Mehdi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Jacques Ohayon
- Savoie Mont-Blanc University, Polytech Annecy-Chambéry, Le Bourget du Lac, France
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX 77030, USA
| | - Prasanna G Alluri
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sakthivel Sadayappan
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Gaurav Choudhary
- Department of Medicine, Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX 77030, USA
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
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14
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Liu W, LeBar K, Roth K, Pang J, Ayers J, Chicco AJ, Puttlitz CM, Wang Z. Alterations of biaxial viscoelastic properties of the right ventricle in pulmonary hypertension development in rest and acute stress conditions. Front Bioeng Biotechnol 2023; 11:1182703. [PMID: 37324443 PMCID: PMC10266205 DOI: 10.3389/fbioe.2023.1182703] [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: 03/09/2023] [Accepted: 05/17/2023] [Indexed: 06/17/2023] Open
Abstract
Introduction: The right ventricle (RV) mechanical property is an important determinant of its function. However, compared to its elasticity, RV viscoelasticity is much less studied, and it remains unclear how pulmonary hypertension (PH) alters RV viscoelasticity. Our goal was to characterize the changes in RV free wall (RVFW) anisotropic viscoelastic properties with PH development and at varied heart rates. Methods: PH was induced in rats by monocrotaline treatment, and the RV function was quantified by echocardiography. After euthanasia, equibiaxial stress relaxation tests were performed on RVFWs from healthy and PH rats at various strain-rates and strain levels, which recapitulate physiological deformations at varied heart rates (at rest and under acute stress) and diastole phases (at early and late filling), respectively. Results and Discussion: We observed that PH increased RVFW viscoelasticity in both longitudinal (outflow tract) and circumferential directions. The tissue anisotropy was pronounced for the diseased RVs, not healthy RVs. We also examined the relative change of viscosity to elasticity by the damping capacity (ratio of dissipated energy to total energy), and we found that PH decreased RVFW damping capacity in both directions. The RV viscoelasticity was also differently altered from resting to acute stress conditions between the groups-the damping capacity was decreased only in the circumferential direction for healthy RVs, but it was reduced in both directions for diseased RVs. Lastly, we found some correlations between the damping capacity and RV function indices and there was no correlation between elasticity or viscosity and RV function. Thus, the RV damping capacity may be a better indicator of RV function than elasticity or viscosity alone. These novel findings on RV dynamic mechanical properties offer deeper insights into the role of RV biomechanics in the adaptation of RV to chronic pressure overload and acute stress.
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Affiliation(s)
- Wenqiang Liu
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, United States
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Kristen LeBar
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Kellan Roth
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Jassia Pang
- Laboratory Animal Resources, Colorado State University, Fort Collins, CO, United States
| | - Jessica Ayers
- Laboratory Animal Resources, Colorado State University, Fort Collins, CO, United States
| | - Adam J. Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
| | - Christian M. Puttlitz
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Zhijie Wang
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
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15
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Baghersad S, Sathish Kumar A, Kipper MJ, Popat K, Wang Z. Recent Advances in Tissue-Engineered Cardiac Scaffolds-The Progress and Gap in Mimicking Native Myocardium Mechanical Behaviors. J Funct Biomater 2023; 14:jfb14050269. [PMID: 37233379 DOI: 10.3390/jfb14050269] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/04/2023] [Accepted: 05/06/2023] [Indexed: 05/27/2023] Open
Abstract
Heart failure is the leading cause of death in the US and worldwide. Despite modern therapy, challenges remain to rescue the damaged organ that contains cells with a very low proliferation rate after birth. Developments in tissue engineering and regeneration offer new tools to investigate the pathology of cardiac diseases and develop therapeutic strategies for heart failure patients. Tissue -engineered cardiac scaffolds should be designed to provide structural, biochemical, mechanical, and/or electrical properties similar to native myocardium tissues. This review primarily focuses on the mechanical behaviors of cardiac scaffolds and their significance in cardiac research. Specifically, we summarize the recent development of synthetic (including hydrogel) scaffolds that have achieved various types of mechanical behavior-nonlinear elasticity, anisotropy, and viscoelasticity-all of which are characteristic of the myocardium and heart valves. For each type of mechanical behavior, we review the current fabrication methods to enable the biomimetic mechanical behavior, the advantages and limitations of the existing scaffolds, and how the mechanical environment affects biological responses and/or treatment outcomes for cardiac diseases. Lastly, we discuss the remaining challenges in this field and suggestions for future directions to improve our understanding of mechanical control over cardiac function and inspire better regenerative therapies for myocardial restoration.
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Affiliation(s)
- Somayeh Baghersad
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Abinaya Sathish Kumar
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Matt J Kipper
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA
- School of Materials Science and Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Ketul Popat
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
- School of Materials Science and Engineering, Colorado State University, Fort Collins, CO 80523, USA
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Zhijie Wang
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA
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16
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Kakaletsis S, Malinowski M, Mathur M, Sugerman GP, Lucy JJ, Snider C, Jazwiec T, Bersi M, Timek TA, Rausch MK. Untangling the mechanisms of pulmonary hypertension-induced right ventricular stiffening in a large animal model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.03.535491. [PMID: 37066294 PMCID: PMC10104078 DOI: 10.1101/2023.04.03.535491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Background Pulmonary arterial hypertension (PHT) is a devastating disease with low survival rates. In PHT, chronic pressure overload leads to right ventricle (RV) remodeling and stiffening; thus, impeding diastolic filling and ventricular function. Multiple mechanisms contribute to RV stiffening, including wall thickening, microstructural disorganization, and myocardial stiffening. The relative importance of each mechanism is unclear. Our objective is to use a large animal model as well as imaging, experimental, and computational approaches to untangle these mechanisms. Methods We induced PHT in eight sheep via pulmonary artery banding. After eight weeks, the hearts underwent anatomic and diffusion tensor MRI to characterize wall thickening and microstructural disorganization. Additionally, myocardial samples underwent histological and gene expression analyses to quantify compositional changes and mechanical testing to quantify myocardial stiffening. All findings were compared to 12 control animals. Finally, we used computational modeling to disentangle the relative importance of each stiffening mechanism. Results First, we found that the RVs of PHT animals thickened most at the base and the free wall. Additionally, we found that PHT induced excessive collagen synthesis and microstructural disorganization, consistent with increased expression of fibrotic genes. We also found that the myocardium itself stiffened significantly. Importantly, myocardial stiffening correlated significantly with excess collagen synthesis. Finally, our model of normalized RV pressure-volume relationships predicted that myocardial stiffness contributes to RV stiffening significantly more than other mechanisms. Conclusions In summary, we found that PHT induces wall thickening, microstructural disorganization, and myocardial stiffening. These remodeling mechanisms were both spatially and directionally dependent. Using modeling, we show that myocardial stiffness is the primary contributor to RV stiffening. Thus, myocardial stiffening may be an important predictor for PHT progression. Given the significant correlation between myocardial stiffness and collagen synthesis, collagen-sensitive imaging modalities may be useful for non-invasively estimating myocardial stiffness and predicting PHT outcomes.
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Affiliation(s)
- Sotirios Kakaletsis
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX
| | - Marcin Malinowski
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI
- Department of Cardiac Surgery, Medical University of Silesia, Katowice, Poland
| | - Mrudang Mathur
- Department of Mechanical Engineering, The University of Texas at Austin, TX
| | | | - Jeff J. Lucy
- Center for Advanced Brain Imaging Research, Rutgers University, New Brunswick, NJ
| | - Caleb Snider
- Department of Mechanical Engineering & Materials Science, Washington University at St. Louis, St. Louis, MO
| | - Tomasz Jazwiec
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI
- Department of Cardiac, Vascular and Endovascular Surgery and Transplantology, Medical University of Silesia in Katowice, Silesian Centre for Heart Diseases, Zabrze, Poland
| | - Matthew Bersi
- Department of Mechanical Engineering & Materials Science, Washington University at St. Louis, St. Louis, MO
| | - Tomasz A. Timek
- Division of Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI
| | - Manuel K. Rausch
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX
- Department of Biomedical Engineering, The University of Texas at Austin, TX
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17
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Mendiola EA, da Silva Gonçalves Bos D, Leichter DM, Vang A, Zhang P, Leary OP, Gilbert RJ, Avazmohammadi R, Choudhary G. Right Ventricular Architectural Remodeling and Functional Adaptation in Pulmonary Hypertension. Circ Heart Fail 2023; 16:e009768. [PMID: 36748476 PMCID: PMC9974595 DOI: 10.1161/circheartfailure.122.009768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/06/2022] [Indexed: 02/08/2023]
Abstract
BACKGROUND Global indices of right ventricle (RV) function provide limited insights into mechanisms underlying RV remodeling in pulmonary hypertension (PH). While RV myocardial architectural remodeling has been observed in PH, its effect on RV adaptation is poorly understood. METHODS Hemodynamic assessments were performed in 2 rodent models of PH. RV free wall myoarchitecture was quantified using generalized Q-space imaging and tractography analyses. Computational models were developed to predict RV wall strains. Data from animal studies were analyzed to determine the correlations between hemodynamic measurements, RV strains, and structural measures. RESULTS In contrast to the PH rats with severe RV maladaptation, PH rats with mild RV maladaptation showed a decrease in helical range of fiber orientation in the RV free wall (139º versus 97º; P=0.029), preserved global circumferential strain, and exhibited less reduction in right ventricular-pulmonary arterial coupling (0.029 versus 0.017 mm/mm Hg; P=0.037). Helical range correlated positively with coupling (P=0.036) and stroke volume index (P<0.01). Coupling correlated with global circumferential strain (P<0.01) and global radial strain (P<0.01) but not global longitudinal strain. CONCLUSIONS Data analysis suggests that adaptive RV architectural remodeling could improve RV function in PH. Our findings suggest the need to assess RV architecture within routine screenings of PH patients to improve our understanding of its prognostic and therapeutic significance in PH.
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Affiliation(s)
- Emilio A. Mendiola
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Denielli da Silva Gonçalves Bos
- Pulmonary Division–Heart Institute, University of São Paulo Medical School, São Paulo, Brazil
- Vascular Research Laboratory, Providence VA Medical Center, Providence, Rhode Island, USA
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | | | - Alexander Vang
- Vascular Research Laboratory, Providence VA Medical Center, Providence, Rhode Island, USA
- Ocean State Research Institute, Providence, Rhode Island, USA
| | - Peng Zhang
- Vascular Research Laboratory, Providence VA Medical Center, Providence, Rhode Island, USA
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, USA
- Ocean State Research Institute, Providence, Rhode Island, USA
| | - Owen P. Leary
- Ocean State Research Institute, Providence, Rhode Island, USA
| | | | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, 77030, USA
- J. Mike Walker ‘66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Gaurav Choudhary
- Vascular Research Laboratory, Providence VA Medical Center, Providence, Rhode Island, USA
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, USA
- Ocean State Research Institute, Providence, Rhode Island, USA
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18
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Odeigah OO, Valdez-Jasso D, Wall ST, Sundnes J. Computational models of ventricular mechanics and adaptation in response to right-ventricular pressure overload. Front Physiol 2022; 13:948936. [PMID: 36091369 PMCID: PMC9449365 DOI: 10.3389/fphys.2022.948936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/03/2022] [Indexed: 12/13/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is associated with substantial remodeling of the right ventricle (RV), which may at first be compensatory but at a later stage becomes detrimental to RV function and patient survival. Unlike the left ventricle (LV), the RV remains understudied, and with its thin-walled crescent shape, it is often modeled simply as an appendage of the LV. Furthermore, PAH diagnosis is challenging because it often leaves the LV and systemic circulation largely unaffected. Several treatment strategies such as atrial septostomy, right ventricular assist devices (RVADs) or RV resynchronization therapy have been shown to improve RV function and the quality of life in patients with PAH. However, evidence of their long-term efficacy is limited and lung transplantation is still the most effective and curative treatment option. As such, the clinical need for improved diagnosis and treatment of PAH drives a strong need for increased understanding of drivers and mechanisms of RV growth and remodeling (G&R), and more generally for targeted research into RV mechanics pathology. Computational models stand out as a valuable supplement to experimental research, offering detailed analysis of the drivers and consequences of G&R, as well as a virtual test bench for exploring and refining hypotheses of growth mechanisms. In this review we summarize the current efforts towards understanding RV G&R processes using computational approaches such as reduced-order models, three dimensional (3D) finite element (FE) models, and G&R models. In addition to an overview of the relevant literature of RV computational models, we discuss how the models have contributed to increased scientific understanding and to potential clinical treatment of PAH patients.
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Affiliation(s)
| | - Daniela Valdez-Jasso
- Department of Bioengineering, University of California, San Diego, San Diego, CA, United States
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19
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Mendiola EA, Sacks MS, Avazmohammadi R. Mechanical Interaction of the Pericardium and Cardiac Function in the Normal and Hypertensive Rat Heart. Front Physiol 2022; 13:878861. [PMID: 35586708 PMCID: PMC9108501 DOI: 10.3389/fphys.2022.878861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/12/2022] [Indexed: 12/03/2022] Open
Abstract
The pericardium is a thin connective tissue membrane that surrounds the heart and is an integral regulatory component of cardiopulmonary performance. Pathological growth and remodeling of the right ventricle (RV) stemming from structural heart diseases are thought to include a significant role of the pericardium, but its exact role remains unclear. The objective of this study was to investigate potential biomechanical adaptations of the pericardium in response to pulmonary hypertension and their effects on heart behavior. Integrated computational-experimental modeling of the heart offers a robust platform to achieve this objective. We built upon our recently developed high-fidelity finite-element models of healthy and hypertensive rodent hearts via addition of the pericardial sac. In-silico experiments were performed to investigate changes in pericardium reserve elasticity and their effects on cardiac function in hypertensive hearts. Our results suggest that contractile forces would need to increase in the RV and decrease in the left ventricle (LV) in the hypertensive heart to compensate for reductions in pericardium reserve elasticity. The discrepancies between chamber responses to pericardium addition result, in part, from differences in the impact of pericardium on the RV and LV preload. We further demonstrated the capability of our platform to predict the effect of pericardiectomy on heart function. Consistent with previous results, the effect of pericardiectomy on the chamber pressure-volume loop was the largest in the hypertensive RV. These insights are expected to motivate further computational investigations of the effect of pericardiectomy on cardiac function which remains an important factor in surgical planning of constrictive pericarditis and coronary artery bypass grafting.
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Affiliation(s)
- Emilio A. Mendiola
- Computational Cardiovascular Bioengineering Laboratory, Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
| | - Michael S. Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, United States
| | - Reza Avazmohammadi
- Computational Cardiovascular Bioengineering Laboratory, Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
- J. Mike Walker ’66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, United States
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, United States
- *Correspondence: Reza Avazmohammadi,
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20
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Zhang W, Li DS, Bui-Thanh T, Sacks MS. Simulation of the 3D Hyperelastic Behavior of Ventricular Myocardium using a Finite-Element Based Neural-Network Approach. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2022; 394:114871. [PMID: 35422534 PMCID: PMC9004630 DOI: 10.1016/j.cma.2022.114871] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
High-fidelity cardiac models using attribute-rich finite element based models have been developed to a very mature stage. However, such finite-element based approaches remain time consuming, which have limited their clinical use. There remains a need for alternative methods for novel cardiac simulation methods of capable of high fidelity simulations in clinically relevant time frames. Surrogate models are one approach, which traditionally use a data-driven approach for training, requiring the generation of a sufficiently large number of simulation results as the training dataset. Alternatively, a physics-informed neural network can be trained by minimizing the PDE residuals or energy potentials. However, this approach does not provide for a general method to easily using existing finite element models. To address these challenges, we developed a hybrid approach that seamlessly bridged a neural network surrogate model with a differentiable finite element domain representation (NNFE). Given its importance in cardiac simulations, we applied this approach to simulations of the hyperelastic mechanical behavior of ventricular myocardium from recent 3D kinematic constitutive model (J Mech Behav Biomed Mater, 2020 doi: 10.1016/j.jmbbm.2019.103508). We utilized cuboidal domain and conducted numerical studies of individual myocardium specimens discretized by a finite element mesh and assigned with experimentally obtained myofiber architectures. Both parameterized Dirichlet and Neumann boundary conditions were studied. We developed a second-order Newton optimization method, instead of using stochastic gradient descent method, to train the neural network efficiently. The resulting trained neural network surrogate model demonstrated excellent agreement with the corresponding 'ground truth' finite element solutions over the entire physiological deformation range. More importantly, the NNFE approach provided a significantly decreased computational time for a range of finite element mesh sizes for online predictions. For example, as the finite element mesh sized increased from 2744 to 175615 elements the NNFE computational time increased from 0.1108 s to 0.1393 s, while the 'ground truth' FE model increased from 4.541 s to 719.9 s. These results suggests that NNFE run times can be significantly reduced compared with the traditional large-deformation based finite element solution methods. The trade off is to train the NNFE off-line within a range of anticipated physiological responses. However, training time would only have to be performed once before any number of application uses. Moreover, since the NNFE is an analytical function its computational performance will be amplified when the corresponding problem becomes more complex.
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Affiliation(s)
- Wenbo Zhang
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
| | - David S Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
- Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
| | - Tan Bui-Thanh
- Department of Aerospace Engineering and Engineering Mechanics, and Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
- Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
- Department of Aerospace Engineering and Engineering Mechanics, and Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
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21
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Liu W, Nguyen-Truong M, LeBar K, Labus KM, Gray E, Ahern M, Neelakantan S, Avazmohammadi R, McGilvray KC, Puttlitz CM, Wang Z. Multiscale Contrasts Between the Right and Left Ventricle Biomechanics in Healthy Adult Sheep and Translational Implications. Front Bioeng Biotechnol 2022; 10:857638. [PMID: 35528212 PMCID: PMC9068898 DOI: 10.3389/fbioe.2022.857638] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/28/2022] [Indexed: 12/19/2022] Open
Abstract
Cardiac biomechanics play a significant role in the progression of structural heart diseases (SHDs). SHDs alter baseline myocardial biomechanics leading to single or bi-ventricular dysfunction. But therapies for left ventricle (LV) failure patients do not always work well for right ventricle (RV) failure patients. This is partly because the basic knowledge of baseline contrasts between the RV and LV biomechanics remains elusive with limited discrepant findings. The aim of the study was to investigate the multiscale contrasts between LV and RV biomechanics in large animal species. We hypothesize that the adult healthy LV and RV have distinct passive anisotropic biomechanical properties. Ex vivo biaxial tests were performed in fresh sheep hearts. Histology and immunohistochemistry were performed to measure tissue collagen. The experimental data were then fitted to a Fung type model and a structurally informed model, separately. We found that the LV was stiffer in the longitudinal (outflow tract) than circumferential direction, whereas the RV showed the opposite anisotropic behavior. The anisotropic parameter K from the Fung type model accurately captured contrasting anisotropic behaviors in the LV and RV. When comparing the elasticity in the same direction, the LV was stiffer than the RV longitudinally and the RV was stiffer than the LV circumferentially, suggesting different filling patterns of these ventricles during diastole. Results from the structurally informed model suggest potentially stiffer collagen fibers in the LV than RV, demanding further investigation. Finally, type III collagen content was correlated with the low-strain elastic moduli in both ventricles. In summary, our findings provide fundamental biomechanical differences between the chambers. These results provide valuable insights for guiding cardiac tissue engineering and regenerative studies to implement chamber-specific matrix mechanics, which is particularly critical for identifying biomechanical mechanisms of diseases or mechanical regulation of therapeutic responses. In addition, our results serve as a benchmark for image-based inverse modeling technologies to non-invasively estimate myocardial properties in the RV and LV.
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Affiliation(s)
- Wenqiang Liu
- Cardiovascular Biomechanics Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Michael Nguyen-Truong
- Cardiovascular Biomechanics Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Kristen LeBar
- Cardiovascular Biomechanics Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Kevin M. Labus
- Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Elisabeth Gray
- Cardiovascular Biomechanics Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Matt Ahern
- Cardiovascular Biomechanics Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Sunder Neelakantan
- Computation Cardiovascular Bioengineering Lab, Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
| | - Reza Avazmohammadi
- Computation Cardiovascular Bioengineering Lab, Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
- Computation Cardiovascular Bioengineering Lab, J. Mike Walker ’66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, United States
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, United States
| | - Kirk C. McGilvray
- Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
- Orthopaedic Bioengineering Research Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Christian M. Puttlitz
- Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
- Orthopaedic Bioengineering Research Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Zhijie Wang
- Cardiovascular Biomechanics Laboratory, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
- Cardiovascular Biomechanics Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
- *Correspondence: Zhijie Wang,
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22
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Sharifi Kia D, Shen Y, Bachman TN, Goncharova EA, Kim K, Simon MA. The Effects of Healthy Aging on Right Ventricular Structure and Biomechanical Properties: A Pilot Study. Front Med (Lausanne) 2022; 8:751338. [PMID: 35083230 PMCID: PMC8784691 DOI: 10.3389/fmed.2021.751338] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 12/01/2021] [Indexed: 11/13/2022] Open
Abstract
Healthy aging has been associated with alterations in pulmonary vascular and right ventricular (RV) hemodynamics, potentially leading to RV remodeling. Despite the current evidence suggesting an association between aging and alterations in RV function and higher prevalence of pulmonary hypertension in the elderly, limited data exist on age-related differences in RV structure and biomechanics. In this work, we report our preliminary findings on the effects of healthy aging on RV structure, function, and biomechanical properties. Hemodynamic measurements, biaxial mechanical testing, constitutive modeling, and quantitative transmural histological analysis were employed to study two groups of male Sprague-Dawley rats: control (11 weeks) and aging (80 weeks). Aging was associated with increases in RV peak pressures (+17%, p = 0.017), RV contractility (+52%, p = 0.004), and RV wall thickness (+38%, p = 0.001). Longitudinal realignment of RV collagen (16.4°, p = 0.013) and myofibers (14.6°, p = 0.017) were observed with aging, accompanied by transmural cardiomyocyte loss and fibrosis. Aging led to increased RV myofiber stiffness (+141%, p = 0.003), in addition to a bimodal alteration in the biaxial biomechanical properties of the RV free wall, resulting in increased tissue-level stiffness in the low-strain region, while progressing into decreased stiffness at higher strains. Our results demonstrate that healthy aging may modulate RV remodeling via increased peak pressures, cardiomyocyte loss, fibrosis, fiber reorientation, and altered mechanical properties in male Sprague-Dawley rats. Similarities were observed between aging-induced remodeling patterns and those of RV remodeling in pressure overload. These findings may help our understanding of age-related changes in the cardiovascular fitness and response to disease.
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Affiliation(s)
- Danial Sharifi Kia
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Yuanjun Shen
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States
- Davis School of Medicine Lung Center, University of California, Davis, Davis, CA, United States
| | - Timothy N. Bachman
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States
| | - Elena A. Goncharova
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States
- Davis School of Medicine Lung Center, University of California, Davis, Davis, CA, United States
- Division of Pulmonary, Allergy and Critical Care Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kang Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States
- Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, United States
- Division of Cardiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, United States
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, United States
- Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, PA, United States
| | - Marc A. Simon
- Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
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23
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Sharifi Kia D, Kim K, Simon MA. Current Understanding of the Right Ventricle Structure and Function in Pulmonary Arterial Hypertension. Front Physiol 2021; 12:641310. [PMID: 34122125 PMCID: PMC8194310 DOI: 10.3389/fphys.2021.641310] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/30/2021] [Indexed: 12/20/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a disease resulting in increased right ventricular (RV) afterload and RV remodeling. PAH results in altered RV structure and function at different scales from organ-level hemodynamics to tissue-level biomechanical properties, fiber-level architecture, and cardiomyocyte-level contractility. Biomechanical analysis of RV pathophysiology has drawn significant attention over the past years and recent work has found a close link between RV biomechanics and physiological function. Building upon previously developed techniques, biomechanical studies have employed multi-scale analysis frameworks to investigate the underlying mechanisms of RV remodeling in PAH and effects of potential therapeutic interventions on these mechanisms. In this review, we discuss the current understanding of RV structure and function in PAH, highlighting the findings from recent studies on the biomechanics of RV remodeling at organ, tissue, fiber, and cellular levels. Recent progress in understanding the underlying mechanisms of RV remodeling in PAH, and effects of potential therapeutics, will be highlighted from a biomechanical perspective. The clinical relevance of RV biomechanics in PAH will be discussed, followed by addressing the current knowledge gaps and providing suggested directions for future research.
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Affiliation(s)
- Danial Sharifi Kia
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kang Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States.,Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, United States.,Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh - University of Pittsburgh Medical Center, Pittsburgh, PA, United States.,McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, PA, United States
| | - Marc A Simon
- Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
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24
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Kakaletsis S, Meador WD, Mathur M, Sugerman GP, Jazwiec T, Malinowski M, Lejeune E, Timek TA, Rausch MK. Right ventricular myocardial mechanics: Multi-modal deformation, microstructure, modeling, and comparison to the left ventricle. Acta Biomater 2021; 123:154-166. [PMID: 33338654 PMCID: PMC7946450 DOI: 10.1016/j.actbio.2020.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 01/03/2023]
Abstract
The right ventricular myocardium, much like the rest of the right side of the heart, has been consistently understudied. Presently, little is known about its mechanics, its microstructure, and its constitutive behavior. In this work, we set out to provide the first data on the mechanics of the mature right ventricular myocardium in both simple shear and uniaxial loading and to compare these data to the mechanics of the left ventricular myocardium. To this end, we tested ovine tissue samples of the right and left ventricle under a comprehensive mechanical testing protocol that consisted of six simple shear modes and three tension/compression modes. After mechanical testing, we conducted a histology-based microstructural analysis on each right ventricular sample that yielded high resolution fiber distribution maps across the entire samples. Equipped with this detailed mechanical and histological data, we employed an inverse finite element framework to determine the optimal form and parameters for microstructure-based constitutive models. The results of our study show that right ventricular myocardium is less stiff then the left ventricular myocardium in the fiber direction, but similarly exhibits non-linear, anisotropic, and tension/compression asymmetric behavior with direction-dependent Poynting effect. In addition, we found that right ventricular myocardial fibers change angles transmurally and are dispersed within the sheet plane and normal to it. Through our inverse finite element analysis, we found that the Holzapfel model successfully fits these data, even when selectively informed by rudimentary microstructural information. And, we found that the inclusion of higher-fidelity microstructural data improved the Holzapfel model's predictive ability. Looking forward, this investigation is a critical step towards understanding the fundamental mechanical behavior of right ventricular myocardium and lays the groundwork for future whole-organ mechanical simulations.
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Affiliation(s)
- Sotirios Kakaletsis
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX 78712, USA
| | - William D Meador
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mrudang Mathur
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Gabriella P Sugerman
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Tomasz Jazwiec
- Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA; Department of Cardiac, Vascular, and Endovascular Surgery and Transplantology, Medical University of Silesia School of Medicine in Katowice, Silesian Centre for Heart Diseases, Zabrze, Poland
| | - Marcin Malinowski
- Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA; Department of Cardiac Surgery, Medical University of Silesia School of Medicine in Katowice, Katowice, Poland
| | - Emma Lejeune
- Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA
| | - Tomasz A Timek
- Cardiothoracic Surgery, Spectrum Health, Grand Rapids, MI, 49503, USA
| | - Manuel K Rausch
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX 78712, USA; Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA; Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA.
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25
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Sharifi Kia D, Fortunato R, Maiti S, Simon MA, Kim K. An exploratory assessment of stretch-induced transmural myocardial fiber kinematics in right ventricular pressure overload. Sci Rep 2021; 11:3587. [PMID: 33574400 PMCID: PMC7878470 DOI: 10.1038/s41598-021-83154-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 01/22/2021] [Indexed: 01/30/2023] Open
Abstract
Right ventricular (RV) remodeling and longitudinal fiber reorientation in the setting of pulmonary hypertension (PH) affects ventricular structure and function, eventually leading to RV failure. Characterizing the kinematics of myocardial fibers helps better understanding the underlying mechanisms of fiber realignment in PH. In the current work, high-frequency ultrasound imaging and structurally-informed finite element (FE) models were employed for an exploratory evaluation of the stretch-induced kinematics of RV fibers. Image-based experimental evaluation of fiber kinematics in porcine myocardium revealed the capability of affine assumptions to effectively approximate myofiber realignment in the RV free wall. The developed imaging framework provides a noninvasive modality to quantify transmural RV myofiber kinematics in large animal models. FE modeling results demonstrated that chronic pressure overload, but not solely an acute rise in pressures, results in kinematic shift of RV fibers towards the longitudinal direction. Additionally, FE simulations suggest a potential protective role for concentric hypertrophy (increased wall thickness) against fiber reorientation, while eccentric hypertrophy (RV dilation) resulted in longitudinal fiber realignment. Our study improves the current understanding of the role of different remodeling events involved in transmural myofiber reorientation in PH. Future experimentations are warranted to test the model-generated hypotheses.
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Affiliation(s)
- Danial Sharifi Kia
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA
| | - Ronald Fortunato
- grid.21925.3d0000 0004 1936 9000Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA USA
| | - Spandan Maiti
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA USA
| | - Marc A. Simon
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, 623A Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15213 USA ,grid.412689.00000 0001 0650 7433Heart and Vascular Institute, University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.412689.00000 0001 0650 7433Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA USA
| | - Kang Kim
- grid.21925.3d0000 0004 1936 9000Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, 623A Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15213 USA ,grid.412689.00000 0001 0650 7433Heart and Vascular Institute, University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.412689.00000 0001 0650 7433Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh and University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA USA ,grid.21925.3d0000 0004 1936 9000Center for Ultrasound Molecular Imaging and Therapeutics, University of Pittsburgh, Pittsburgh, PA USA
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26
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Redaelli A, Votta E. Cardiovascular patient-specific modeling: Where are we now and what does the future look like? APL Bioeng 2020; 4:040401. [PMID: 33195957 DOI: 10.1063/5.0031452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022] Open
Affiliation(s)
- Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
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27
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Sharifi Kia D, Benza E, Bachman TN, Tushak C, Kim K, Simon MA. Angiotensin Receptor-Neprilysin Inhibition Attenuates Right Ventricular Remodeling in Pulmonary Hypertension. J Am Heart Assoc 2020; 9:e015708. [PMID: 32552157 PMCID: PMC7670537 DOI: 10.1161/jaha.119.015708] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Background Pulmonary hypertension (PH) results in increased right ventricular (RV) afterload and ventricular remodeling. Sacubitril/valsartan (sac/val) is a dual acting drug, composed of the neprilysin inhibitor sacubitril and the angiotensin receptor blocker valsartan, that has shown promising outcomes in reducing the risk of death and hospitalization for chronic systolic left ventricular heart failure. In this study, we aimed to examine if angiotensin receptor‐neprilysin inhibition using sac/val attenuates RV remodeling in PH. Methods and Results RV pressure overload was induced in Sprague–Dawley rats via banding the main pulmonary artery. Three different cohorts of controls, placebo‐treated PH, and sac/val‐treated PH were studied in a 21‐day treatment window. Terminal invasive hemodynamic measurements, quantitative histological analysis, biaxial mechanical testing, and constitutive modeling were employed to conduct a multiscale analysis on the effects of sac/val on RV remodeling in PH. Sac/val treatment decreased RV maximum pressures (29% improvement, P=0.002), improved RV contractile (30%, P=0.012) and relaxation (29%, P=0.043) functions, reduced RV afterload (35% improvement, P=0.016), and prevented RV‐pulmonary artery uncoupling. Furthermore, sac/val attenuated RV hypertrophy (16% improvement, P=0.006) and prevented transmural reorientation of RV collagen and myofibers (P=0.011). The combined natriuresis and vasodilation resulting from sac/val led to improved RV biomechanical properties and prevented increased myofiber stiffness in PH (61% improvement, P=0.032). Conclusions Sac/val may prevent maladaptive RV remodeling in a pressure overload model via amelioration of RV pressure rise, hypertrophy, collagen, and myofiber reorientation as well as tissue stiffening both at the tissue and myofiber level.
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Affiliation(s)
| | - Evan Benza
- Heart and Vascular InstituteUniversity of Pittsburgh Medical Center (UPMC)Pittsburgh PA
| | - Timothy N Bachman
- Department of BioengineeringUniversity of PittsburghPA.,Pittsburgh Heart, Lung, Blood and Vascular Medicine InstituteUniversity of Pittsburgh and University of Pittsburgh Medical Center (UPMC)Pittsburgh PA
| | - Claire Tushak
- Department of BioengineeringUniversity of PittsburghPA
| | - Kang Kim
- Department of BioengineeringUniversity of PittsburghPA.,Heart and Vascular InstituteUniversity of Pittsburgh Medical Center (UPMC)Pittsburgh PA.,Pittsburgh Heart, Lung, Blood and Vascular Medicine InstituteUniversity of Pittsburgh and University of Pittsburgh Medical Center (UPMC)Pittsburgh PA.,Division of CardiologySchool of MedicineUniversity of PittsburghPA.,McGowan Institute for Regenerative MedicineUniversity of PittsburghPA.,Department of Mechanical Engineering and Materials ScienceUniversity of PittsburghPA.,Center for Ultrasound Molecular Imaging and TherapeuticsUniversity of PittsburghPA
| | - Marc A Simon
- Department of BioengineeringUniversity of PittsburghPA.,Heart and Vascular InstituteUniversity of Pittsburgh Medical Center (UPMC)Pittsburgh PA.,Pittsburgh Heart, Lung, Blood and Vascular Medicine InstituteUniversity of Pittsburgh and University of Pittsburgh Medical Center (UPMC)Pittsburgh PA.,Division of CardiologySchool of MedicineUniversity of PittsburghPA.,McGowan Institute for Regenerative MedicineUniversity of PittsburghPA
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28
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Abstract
Right-sided heart failure (RHF) occurs from impaired contractility of the right ventricle caused by pressure, volume overload, or intrinsic myocardial contractile dysfunction. The development of subclinical right ventricle (RV) dysfunction or overt RHF is a negative prognostic indicator. Recent attention has focused on RV-specific inflammatory growth factors and mediators of myocardial fibrosis to elucidate the mechanisms leading to RHF and potentially guide the development of novel therapeutics. This article focuses on the distinct changes in RV structure, mechanics, and function, as well as molecular and inflammatory mediators involved in the pathophysiology of acute and chronic RHF.
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Affiliation(s)
| | - Kalyan R Chitturi
- Houston Methodist DeBakey Heart & Vascular Center, 6550 Fannin Street, Houston, TX 77030, USA
| | - Ashrith Guha
- Houston Methodist DeBakey Heart & Vascular Center, 6550 Fannin Street, Houston, TX 77030, USA.
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29
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Redaelli A, Cooper-White J. Bioengineering of the heart. APL Bioeng 2020; 4:010402. [DOI: 10.1063/1.5144525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/19/2020] [Indexed: 11/15/2022] Open
Affiliation(s)
- Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano 20133, Italy
| | - Justin Cooper-White
- Tissue Engineering and Microfluidics Laboratory (TE&M), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, St. Lucia, QLD 406, Australia
- The UQ Centre in Stem Cell Ageing and Regenerative Engineering (StemCARE), Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, QLD 4067,
Australia
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Manufacturing, Melbourne, Clayton, VIC 3168,
Australia
- School of Chemical Engineering, The University of Queensland, Brisbane, St. Lucia, QLD 4067,
Australia
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30
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Li DS, Avazmohammadi R, Merchant SS, Kawamura T, Hsu EW, Gorman JH, Gorman RC, Sacks MS. Insights into the passive mechanical behavior of left ventricular myocardium using a robust constitutive model based on full 3D kinematics. J Mech Behav Biomed Mater 2020; 103:103508. [PMID: 32090941 PMCID: PMC7045908 DOI: 10.1016/j.jmbbm.2019.103508] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 09/30/2019] [Accepted: 10/23/2019] [Indexed: 02/06/2023]
Abstract
Myocardium possesses a hierarchical structure that results in complex three-dimensional (3D) mechanical behavior, forming a critical component of ventricular function in health and disease. A wide range of constitutive model forms have been proposed for myocardium since the first planar biaxial studies were performed by Demer and Yin (J. Physiol. 339 (1), 1983). While there have been extensive studies since, none have been based on full 3D kinematic data, nor have they utilized optimal experimental design to estimate constitutive parameters, which may limit their predictive capability. Herein we have applied our novel 3D numerical-experimental methodology (Avazmohammadi et al., Biomechanics Model. Mechanobiol. 2018) to explore the applicability of an orthotropic constitutive model for passive ventricular myocardium (Holzapfel and Ogden, Philos. Trans. R. Soc. Lond.: Math. Phys. Eng. Sci. 367, 2009) by integrating 3D optimal loading paths, spatially varying material structure, and inverse modeling techniques. Our findings indicated that the initial model form was not successful in reproducing all optimal loading paths, due to previously unreported coupling behaviors via shearing of myofibers and extracellular collagen fibers in the myocardium. This observation necessitated extension of the constitutive model by adding two additional terms based on the I8(C) pseudo-invariant in the fiber-normal and sheet-normal directions. The modified model accurately reproduced all optimal loading paths and exhibited improved predictive capabilities. These unique results suggest that more complete constitutive models are required to fully capture the full 3D biomechanical response of left ventricular myocardium. The present approach is thus crucial for improved understanding and performance in cardiac modeling in healthy, diseased, and treatment scenarios.
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Affiliation(s)
- David S Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Reza Avazmohammadi
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Samer S Merchant
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, 84112, USA
| | - Tomonori Kawamura
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Edward W Hsu
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, 84112, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
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31
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Mikhael M, Makar C, Wissa A, Le T, Eghbali M, Umar S. Oxidative Stress and Its Implications in the Right Ventricular Remodeling Secondary to Pulmonary Hypertension. Front Physiol 2019; 10:1233. [PMID: 31607955 PMCID: PMC6769067 DOI: 10.3389/fphys.2019.01233] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/09/2019] [Indexed: 02/06/2023] Open
Abstract
Pulmonary hypertension (PH) is a pulmonary vascular disease characterized by increased pulmonary artery pressures. Long standing pulmonary arterial pressure overload leads to right ventricular (RV) hypertrophy, RV failure, and death. RV failure is a major determinant of survival in PH. Oxidative stress has been associated with the development of RV failure secondary to PH. Here we summarize the structural and functional changes in the RV in response to sustained pulmonary arterial pressure overload. Furthermore, we review the pre-clinical and clinical studies highlighting the association of oxidative stress with pulmonary vasculature and RV remodeling in chronic PH. Targeting oxidative stress promises to be an effective therapeutic strategy for the treatment of RV failure.
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Affiliation(s)
- Matthew Mikhael
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Christian Makar
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Amir Wissa
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Trixie Le
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Mansoureh Eghbali
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Soban Umar
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
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Vélez-Rendón D, Pursell ER, Shieh J, Valdez-Jasso D. Relative Contributions of Matrix and Myocytes to Biaxial Mechanics of the Right Ventricle in Pulmonary Arterial Hypertension. J Biomech Eng 2019; 141:091011. [PMID: 31299076 DOI: 10.1115/1.4044225] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Indexed: 01/15/2023]
Abstract
Pulmonary arterial hypertension (PAH) commonly leads to right ventricular (RV) hypertrophy and fibrosis that affect the mechanical properties of the RV myocardium (MYO). To investigate the effects of PAH on the mechanics of the RV MYO and extracellular matrix (ECM), we compared RV wall samples, isolated from rats in which PAH was induced using the SuHx protocol, with samples from control animals before and after the tissues were decellularized. Planar biaxial mechanical testing, a technique first adapted to living soft biological tissues by Fung, was performed on intact and decellularized samples. Fung's anisotropic exponential strain energy function fitted the full range of biaxial test results with high fidelity in control and PAH samples both before and after they were decellularized. Mean RV myocardial apex-to-outflow tract and circumferential stresses during equibiaxial strain were significantly greater in PAH than control samples. Mean RV ECM circumferential but not apex-to-outflow tract stresses during equibiaxial strain were significantly greater in the PAH than control group. The ratio of ECM to myocardial stresses at matched strains did not change significantly between groups. Circumferential stresses were significantly higher than apex-to-outflow tract stresses for all groups. These findings confirm the predictions of a mathematical model based on changes in RV hemodynamics and morphology in rat PAH, and may provide a foundation for a new constitutive analysis of the contributions of ECM remodeling to changes in RV filling properties during PAH.
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Affiliation(s)
- Daniela Vélez-Rendón
- Department of Bioengineering,University of Illinois at Chicago,Chicago, IL 60607
| | - Erica R Pursell
- Bioengineering Department,University of California San Diego,La Jolla, CA 92122
| | - Justin Shieh
- Bioengineering Department,University of California San Diego,La Jolla, CA 92122
| | - Daniela Valdez-Jasso
- Bioengineering Department,University of California, San Diego,La Jolla, CA 92122e-mail:
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Guan D, Ahmad F, Theobald P, Soe S, Luo X, Gao H. On the AIC-based model reduction for the general Holzapfel-Ogden myocardial constitutive law. Biomech Model Mechanobiol 2019; 18:1213-1232. [PMID: 30945052 PMCID: PMC6647490 DOI: 10.1007/s10237-019-01140-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/19/2019] [Indexed: 12/11/2022]
Abstract
Constitutive laws that describe the mechanical responses of cardiac tissue under loading hold the key to accurately model the biomechanical behaviour of the heart. There have been ample choices of phenomenological constitutive laws derived from experiments, some of which are quite sophisticated and include effects of microscopic fibre structures of the myocardium. A typical example is the strain-invariant-based Holzapfel-Ogden 2009 model that is excellently fitted to simple shear tests. It has been widely used and regarded as the state-of-the-art constitutive law for myocardium. However, there has been no analysis to show if it has both adequate descriptive and predictive capabilities for other tissue tests of myocardium. Indeed, such an analysis is important for any constitutive laws for clinically useful computational simulations. In this work, we perform such an analysis using combinations of tissue tests, uniaxial tension, biaxial tension and simple shear from three different sets of myocardial tissue studies. Starting from the general 14-parameter myocardial constitutive law developed by Holzapfel and Ogden, denoted as the general HO model, we show that this model has good descriptive and predictive capabilities for all the experimental tests. However, to reliably determine all 14 parameters of the model from experiments remains a great challenge. Our aim is to reduce the constitutive law using Akaike information criterion, to maintain its mechanical integrity whilst achieving minimal computational cost. A competent constitutive law should have descriptive and predictive capabilities for different tissue tests. By competent, we mean the model has least terms but is still able to describe and predict experimental data. We also investigate the optimal combinations of tissue tests for a given constitutive model. For example, our results show that using one of the reduced HO models, one may need just one shear response (along normal-fibre direction) and one biaxial stretch (ratio of 1 mean fibre : 1 cross-fibre) to satisfactorily describe Sommer et al. human myocardial mechanical properties. Our study suggests that single-state tests (i.e. simple shear or stretching only) are insufficient to determine the myocardium responses. We also found it is important to consider transmural fibre rotations within each myocardial sample of tests during the fitting process. This is done by excluding un-stretched fibres using an "effective fibre ratio", which depends on the sample size, shape, local myofibre architecture and loading conditions. We conclude that a competent myocardium material model can be obtained from the general HO model using AIC analysis and a suitable combination of tissue tests.
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Affiliation(s)
- Debao Guan
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Faizan Ahmad
- School of Engineering, Cardiff University, Cardiff, UK
| | | | - Shwe Soe
- School of Engineering, Cardiff University, Cardiff, UK
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
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Avazmohammadi R, Mendiola E, Li D, Vanderslice P, Dixon R, Sacks M. Interactions between structural remodeling and volumetric growth in right ventricle in response to pulmonary arterial hypertension. J Biomech Eng 2019; 141:2737741. [PMID: 31260516 DOI: 10.1115/1.4044174] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Indexed: 01/22/2023]
Abstract
Pulmonary arterial hypertension (PAH) exerts substantial pressure overload on the right ventricle (RV). The associated RV free wall (RVFW) adaptation could consist of myocardial hypertrophy, augmented intrinsic contractility, collagen fibrosis, and structural remodeling in an attempt to cope with pressure overload. If RVFW adaptation cannot maintain the RV stroke volume, RV dilation will prevail as an exit mechanism which usually decompensates the RV function leading to RV failure. Our knowledge of the factors determining the transition from the upper limit of RVFW adaptation to RV decompensation and the role of fiber remodeling events in this transition remains very limited. Computational heart models that connect the growth and remodeling (G\&R) events at the fiber and tissue levels with alterations in the organ-level function are essential to predict the temporal order and the compensatory level of the underlying mechanisms. In this work, building upon our recent rodent heart models (RHM) of PAH, we integrated mathematical models that describe time-evolution volumetric growth of the RV and structural remodeling of the RVFW. Results suggest that augmentation of the intrinsic contractility of myofibers accompanied by an increase in passive stiffness of RVFW is among the first remodeling events through which the RV strives to maintain the cardiac output. Interestingly, we found that the observed reorientation of the myofibers towards the longitudinal (apex-to-base) direction was a maladaptive mechanism that impaired the contractile pattern of RVFW and advanced along with RV dilation at later stages of PAH development.
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Affiliation(s)
- Reza Avazmohammadi
- James T. Willerson Center for Cardiovascular Modeling and Simulation Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering
| | - Emilio Mendiola
- James T. Willerson Center for Cardiovascular Modeling and Simulation Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering
| | - David Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering
| | - Peter Vanderslice
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA; The University of Texas at Austin, Austin, TX, USA
| | - Richard Dixon
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA; The University of Texas at Austin, Austin, TX, USA
| | - Michael Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering
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Avazmohammadi R, Soares JS, Li DS, Raut SS, Gorman RC, Sacks MS. A Contemporary Look at Biomechanical Models of Myocardium. Annu Rev Biomed Eng 2019; 21:417-442. [PMID: 31167105 PMCID: PMC6626320 DOI: 10.1146/annurev-bioeng-062117-121129] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Understanding and predicting the mechanical behavior of myocardium under healthy and pathophysiological conditions are vital to developing novel cardiac therapies and promoting personalized interventions. Within the past 30 years, various constitutive models have been proposed for the passive mechanical behavior of myocardium. These models cover a broad range of mathematical forms, microstructural observations, and specific test conditions to which they are fitted. We present a critical review of these models, covering both phenomenological and structural approaches, and their relations to the underlying structure and function of myocardium. We further explore the experimental and numerical techniques used to identify the model parameters. Next, we provide a brief overview of continuum-level electromechanical models of myocardium, with a focus on the methods used to integrate the active and passive components of myocardial behavior. We conclude by pointing to future directions in the areas of optimal form as well as new approaches for constitutive modeling of myocardium.
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Affiliation(s)
- Reza Avazmohammadi
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, and Department of Biomedical Engineering, University of Texas, Austin, Texas 78712, USA;
| | - João S Soares
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, and Department of Biomedical Engineering, University of Texas, Austin, Texas 78712, USA;
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, USA
| | - David S Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, and Department of Biomedical Engineering, University of Texas, Austin, Texas 78712, USA;
| | - Samarth S Raut
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, and Department of Biomedical Engineering, University of Texas, Austin, Texas 78712, USA;
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, and Department of Biomedical Engineering, University of Texas, Austin, Texas 78712, USA;
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Shavik SM, Zhong L, Zhao X, Lee LC. In-silico assessment of the effects of right ventricular assist device on pulmonary arterial hypertension using an image based biventricular modeling framework. MECHANICS RESEARCH COMMUNICATIONS 2019; 97:101-111. [PMID: 31983787 PMCID: PMC6980470 DOI: 10.1016/j.mechrescom.2019.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Pulmonary arterial hypertension (PAH) is a heart disease that is characterized by an abnormally high pressure in the pulmonary artery (PA). While right ventricular assist device (RVAD) has been considered recently as a treatment option for the end-stage PAH patients, its effects on biventricular mechanics are, however, largely unknown. To address this issue, we developed an image-based modeling framework consisting of a biventricular finite element (FE) model that is coupled to a lumped model describing the pulmonary and systemic circulations in a closed-loop system. The biventricular geometry was reconstructed from the magnetic resonance images of two PAH patients showing different degree of RV remodeling and a normal subject. The framework was calibrated to match patient-specific measurements of the left ventricular (LV) and RV volume and pressure waveforms. An RVAD model was incorporated into the calibrated framework and simulations were performed with different pump speeds. Results showed that RVAD unloads the RV, improves cardiac output and increases septum curvature, which are more pronounced in the PAH patient with severe RV remodeling. These improvements, however, are also accompanied by an adverse increase in the PA pressure. These results suggest that the RVAD implantation may need to be optimized depending on disease progression.
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Affiliation(s)
- Sheikh Mohammad Shavik
- Department of mechanical engineering, Michigan State University, East Lansing, Michigan, USA
| | - Liang Zhong
- National Heart Research Institute Singapore, National Heart Center Singapore, Singapore
- Duke-NUS Medical School, National University of Singapore
| | - Xiaodan Zhao
- National Heart Research Institute Singapore, National Heart Center Singapore, Singapore
| | - Lik Chuan Lee
- Department of mechanical engineering, Michigan State University, East Lansing, Michigan, USA
- Corresponding author: , Tel.: +1-517-432-4563; fax: +1-517-355-8339
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Avazmohammadi R, Mendiola EA, Soares JS, Li DS, Chen Z, Merchant S, Hsu EW, Vanderslice P, Dixon RAF, Sacks MS. A Computational Cardiac Model for the Adaptation to Pulmonary Arterial Hypertension in the Rat. Ann Biomed Eng 2018; 47:138-153. [PMID: 30264263 DOI: 10.1007/s10439-018-02130-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 09/11/2018] [Indexed: 01/01/2023]
Abstract
Pulmonary arterial hypertension (PAH) imposes pressure overload on the right ventricle (RV), leading to RV enlargement via the growth of cardiac myocytes and remodeling of the collagen fiber architecture. The effects of these alterations on the functional behavior of the right ventricular free wall (RVFW) and organ-level cardiac function remain largely unexplored. Computational heart models in the rat (RHMs) of the normal and hypertensive states can be quite valuable in simulating the effects of PAH on cardiac function to gain insights into the pathophysiology of underlying myocardium remodeling. We thus developed high-fidelity biventricular finite element RHMs for the normal and post-PAH hypertensive states using extensive experimental data collected from rat hearts. We then applied the RHM to investigate the transmural nature of RVFW remodeling and its connection to wall stress elevation under PAH. We found a strong correlation between the longitudinally-dominated fiber-level adaptation of the RVFW and the transmural alterations of relevant wall stress components. We further conducted several numerical experiments to gain new insights on how the RV responds both normally and in the post-PAH state. We found that the effect of pressure overload alone on the increased contractility of the RV is comparable to the effects of changes in the RV geometry and stiffness. Furthermore, our RHMs provided fresh perspectives on long-standing questions of the functional role of the interventricular septum in RV function. Specifically, we demonstrated that an inaccurate identification of the mechanical adaptation of the septum can lead to a significant underestimation of RVFW contractility in the post-PAH state. These findings show how integrated experimental-computational models can facilitate a more comprehensive understanding of the cardiac remodeling events during PAH.
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Affiliation(s)
- Reza Avazmohammadi
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Emilio A Mendiola
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - João S Soares
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - David S Li
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Zhiqiang Chen
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA
| | - Samer Merchant
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Edward W Hsu
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Peter Vanderslice
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA
| | - Richard A F Dixon
- Department of Molecular Cardiology, Texas Heart Institute, Houston, TX, USA
| | - Michael S Sacks
- Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA.
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