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Han Y, Chen T, Addetia K. Tricuspid Valve Prolapse: A Forgotten Mechanism of Primary Tricuspid Regurgitation? J Am Coll Cardiol 2023; 81:S0735-1097(22)07643-4. [PMID: 36813688 DOI: 10.1016/j.jacc.2022.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/12/2022] [Indexed: 02/22/2023]
Affiliation(s)
- Yuchi Han
- Cardiovascular Division, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA. https://twitter.com/tiffchenMD
| | - Tiffany Chen
- Cardiovascular Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Karima Addetia
- Cardiovascular Division, University of Chicago Heart & Vascular Center, Chicago, Illinois, USA
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2
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Anssari-Benam A, Horgan CO. New results in the theory of plane strain flexure of incompressible isotropic hyperelastic materials. Proc Math Phys Eng Sci 2022. [DOI: 10.1098/rspa.2021.0773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
New results on the classical problem of bending by end moments for incompressible isotropic hyperelastic materials within the framework of nonlinear elasticity are investigated and presented in this paper. The particular results of concern here include (i) the adaptation of Rivlin's standard analysis to the case where
one end
of the beam is
fixed
and the other end is subjected to a bending moment; and (ii) results on the finite bending of (infinitesimally)
thin
isotropic hyperelastic plates which are valid for
large deformations
, extending the classical results from the linear elasticity theory which are restricted to small deformations. An interesting feature observed in this context is that a flexed thin plate develops an oscillatory surface along the circular arc near the free end, due to local (small)
deviations
of the radius of curvature. A potential application to the bending of a biological soft tissue, namely the aortic valve leaflet, is briefly described by way of an example. Finally, some new results are obtained for finite bending of hyperelastic materials that exhibit limiting chain extensibility at the molecular level and involve constraints on the deformation. The amount of bending that such materials can sustain is limited by the constraint. On using a limiting chain extensibility model, closed-form solutions for the Cauchy stress components, the bending moment and the normal out-of-plane force required to sustain the bending deformation are derived.
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Affiliation(s)
- Afshin Anssari-Benam
- Cardiovascular Engineering Research Lab (CERL), School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Road, Portsmouth PO1 3DJ, UK
| | - Cornelius O. Horgan
- School of Engineering and Applied Science, University of Virginia, Charlottesville, VA 22904, USA
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Büttner P, Feistner L, Lurz P, Thiele H, Hutcheson JD, Schlotter F. Dissecting Calcific Aortic Valve Disease-The Role, Etiology, and Drivers of Valvular Fibrosis. Front Cardiovasc Med 2021; 8:660797. [PMID: 34041283 PMCID: PMC8143377 DOI: 10.3389/fcvm.2021.660797] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/08/2021] [Indexed: 12/15/2022] Open
Abstract
Calcific aortic valve disease (CAVD) is a highly prevalent and progressive disorder that ultimately causes gradual narrowing of the left ventricular outflow orifice with ensuing devastating hemodynamic effects on the heart. Calcific mineral accumulation is the hallmark pathology defining this process; however, fibrotic extracellular matrix (ECM) remodeling that leads to extensive deposition of fibrous connective tissue and distortion of the valvular microarchitecture similarly has major biomechanical and functional consequences for heart valve function. Significant advances have been made to unravel the complex mechanisms that govern these active, cell-mediated processes, yet the interplay between fibrosis and calcification and the individual contribution to progressive extracellular matrix stiffening require further clarification. Specifically, we discuss (1) the valvular biomechanics and layered ECM composition, (2) patterns in the cellular contribution, temporal onset, and risk factors for valvular fibrosis, (3) imaging valvular fibrosis, (4) biomechanical implications of valvular fibrosis, and (5) molecular mechanisms promoting fibrotic tissue remodeling and the possibility of reverse remodeling. This review explores our current understanding of the cellular and molecular drivers of fibrogenesis and the pathophysiological role of fibrosis in CAVD.
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Affiliation(s)
- Petra Büttner
- Department of Internal Medicine/Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
| | - Lukas Feistner
- Department of Internal Medicine/Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
| | - Philipp Lurz
- Department of Internal Medicine/Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
| | - Holger Thiele
- Department of Internal Medicine/Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
| | - Joshua D. Hutcheson
- Department of Biomedical Engineering, Florida International University, Miami, FL, United States
- Biomolecular Sciences Institute, Florida International University, Miami, FL, United States
| | - Florian Schlotter
- Department of Internal Medicine/Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
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Subject-specific multiscale modeling of aortic valve biomechanics. Biomech Model Mechanobiol 2021; 20:1031-1046. [PMID: 33792805 PMCID: PMC8154826 DOI: 10.1007/s10237-021-01429-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 01/28/2021] [Indexed: 11/13/2022]
Abstract
A Finite Element workflow for the multiscale analysis of the aortic valve biomechanics was developed and applied to three physiological anatomies with the aim of describing the aortic valve interstitial cells biomechanical milieu in physiological conditions, capturing the effect of subject-specific and leaflet-specific anatomical features from the organ down to the cell scale. A mixed approach was used to transfer organ-scale information down to the cell-scale. Displacement data from the organ model were used to impose kinematic boundary conditions to the tissue model, while stress data from the latter were used to impose loading boundary conditions to the cell level. Peak of radial leaflet strains was correlated with leaflet extent variability at the organ scale, while circumferential leaflet strains varied over a narrow range of values regardless of leaflet extent. The dependency of leaflet biomechanics on the leaflet-specific anatomy observed at the organ length-scale is reflected, and to some extent emphasized, into the results obtained at the lower length-scales. At the tissue length-scale, the peak diastolic circumferential and radial stresses computed in the fibrosa correlated with the leaflet surface area. At the cell length-scale, the difference between the strains in two main directions, and between the respective relationships with the specific leaflet anatomy, was even more evident; cell strains in the radial direction varied over a relatively wide range (\documentclass[12pt]{minimal}
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\begin{document}$$0.36-0.87$$\end{document}0.36-0.87) with a strong correlation with the organ length-scale radial strain (\documentclass[12pt]{minimal}
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\begin{document}$$R^{2}= 0.95$$\end{document}R2=0.95); conversely, circumferential cell strains spanned a very narrow range (\documentclass[12pt]{minimal}
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\begin{document}$$0.75-0.88$$\end{document}0.75-0.88) showing no correlation with the circumferential strain at the organ level (\documentclass[12pt]{minimal}
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\begin{document}$$R^{2}= 0.02$$\end{document}R2=0.02). Within the proposed simulation framework, being able to account for the actual anatomical features of the aortic valve leaflets allowed to gain insight into their effect on the structural mechanics of the leaflets at all length-scales, down to the cell scale.
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5
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Biology and Biomechanics of the Heart Valve Extracellular Matrix. J Cardiovasc Dev Dis 2020; 7:jcdd7040057. [PMID: 33339213 PMCID: PMC7765611 DOI: 10.3390/jcdd7040057] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/02/2020] [Accepted: 12/13/2020] [Indexed: 02/06/2023] Open
Abstract
Heart valves are dynamic structures that, in the average human, open and close over 100,000 times per day, and 3 × 109 times per lifetime to maintain unidirectional blood flow. Efficient, coordinated movement of the valve structures during the cardiac cycle is mediated by the intricate and sophisticated network of extracellular matrix (ECM) components that provide the necessary biomechanical properties to meet these mechanical demands. Organized in layers that accommodate passive functional movements of the valve leaflets, heart valve ECM is synthesized during embryonic development, and remodeled and maintained by resident cells throughout life. The failure of ECM organization compromises biomechanical function, and may lead to obstruction or leaking, which if left untreated can lead to heart failure. At present, effective treatment for heart valve dysfunction is limited and frequently ends with surgical repair or replacement, which comes with insuperable complications for many high-risk patients including aged and pediatric populations. Therefore, there is a critical need to fully appreciate the pathobiology of biomechanical valve failure in order to develop better, alternative therapies. To date, the majority of studies have focused on delineating valve disease mechanisms at the cellular level, namely the interstitial and endothelial lineages. However, less focus has been on the ECM, shown previously in other systems, to be a promising mechanism-inspired therapeutic target. Here, we highlight and review the biology and biomechanical contributions of key components of the heart valve ECM. Furthermore, we discuss how human diseases, including connective tissue disorders lead to aberrations in the abundance, organization and quality of these matrix proteins, resulting in instability of the valve infrastructure and gross functional impairment.
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Burkert J, Kochová P, Tonar Z, Cimrman R, Blassová T, Jashari R, Fiala R, Špatenka J. The time has come to extend the expiration limit of cryopreserved allograft heart valves. Cell Tissue Bank 2020; 22:161-184. [PMID: 32583302 DOI: 10.1007/s10561-020-09843-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/13/2020] [Indexed: 12/12/2022]
Abstract
Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surgical point of view, the morphology and mechanical properties of aortic and pulmonary roots represent basic features limiting the EL of C-AHV. The aim of this work was to review methods of AHV tissue structural analysis and mechanical testing from the perspective of suitability for EL validation studies. Microscopic structure analysis of great arterial wall and semilunar leaflets tissue should clearly demonstrate cells as well as the extracellular matrix components by highly reproducible and specific histological staining procedures. Quantitative morphometry using stereological grids has proved to be effective, as the exact statistics was feasible. From mechanical testing methods, tensile test was the most suitable. Young's moduli of elasticity, ultimate stress and strain were shown to represent most important AHV tissue mechanical characteristics, suitable for exact statistical analysis. C-AHV are prepared by many different protocols, so as each TE has to work out own EL for C-AHV.
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Affiliation(s)
- Jan Burkert
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
| | - Petra Kochová
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic. .,NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic.
| | - Zbyněk Tonar
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic.,Department of Histology and Embryology, Biomedical Centre, Faculty of Medicine in Pilsen, Charles University in Prague, Karlovarská 48, 301 66, Pilsen, Czech Republic
| | - Robert Cimrman
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic
| | - Tereza Blassová
- Department of Histology and Embryology, Biomedical Centre, Faculty of Medicine in Pilsen, Charles University in Prague, Karlovarská 48, 301 66, Pilsen, Czech Republic
| | - Ramadan Jashari
- European Homograft Bank, Saint-Jean Clinic, Rue du Meridien 100, 1210, Brussels, Belgium
| | - Radovan Fiala
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
| | - Jaroslav Špatenka
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
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7
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Lee CH, Laurence DW, Ross CJ, Kramer KE, Babu AR, Johnson EL, Hsu MC, Aggarwal A, Mir A, Burkhart HM, Towner RA, Baumwart R, Wu Y. Mechanics of the Tricuspid Valve-From Clinical Diagnosis/Treatment, In-Vivo and In-Vitro Investigations, to Patient-Specific Biomechanical Modeling. Bioengineering (Basel) 2019; 6:E47. [PMID: 31121881 PMCID: PMC6630695 DOI: 10.3390/bioengineering6020047] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 12/29/2022] Open
Abstract
Proper tricuspid valve (TV) function is essential to unidirectional blood flow through the right side of the heart. Alterations to the tricuspid valvular components, such as the TV annulus, may lead to functional tricuspid regurgitation (FTR), where the valve is unable to prevent undesired backflow of blood from the right ventricle into the right atrium during systole. Various treatment options are currently available for FTR; however, research for the tricuspid heart valve, functional tricuspid regurgitation, and the relevant treatment methodologies are limited due to the pervasive expectation among cardiac surgeons and cardiologists that FTR will naturally regress after repair of left-sided heart valve lesions. Recent studies have focused on (i) understanding the function of the TV and the initiation or progression of FTR using both in-vivo and in-vitro methods, (ii) quantifying the biomechanical properties of the tricuspid valve apparatus as well as its surrounding heart tissue, and (iii) performing computational modeling of the TV to provide new insight into its biomechanical and physiological function. This review paper focuses on these advances and summarizes recent research relevant to the TV within the scope of FTR. Moreover, this review also provides future perspectives and extensions critical to enhancing the current understanding of the functioning and remodeling tricuspid valve in both the healthy and pathophysiological states.
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Affiliation(s)
- Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
- Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, OK 73019, USA.
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Colton J Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Katherine E Kramer
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Anju R Babu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha 769008, India.
| | - Emily L Johnson
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ankush Aggarwal
- Glasgow Computational Engineering Centre, School of Engineering, University of Glasgow, Scotland G12 8LT, UK.
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Rheal A Towner
- Advance Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
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8
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Comparative mechanical, morphological, and microstructural characterization of porcine mitral and tricuspid leaflets and chordae tendineae. Acta Biomater 2019; 85:241-252. [PMID: 30579963 DOI: 10.1016/j.actbio.2018.12.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 11/30/2018] [Accepted: 12/19/2018] [Indexed: 11/23/2022]
Abstract
BACKGROUND Healthy function of tricuspid valve (TV) structures is essential to avoid tricuspid regurgitation (TR) and may significantly improve disease prognosis. Mitral valve (MV) structures have been extensively studied, but little is known about the TV and right-sided heart diseases. Therefore, clinical decisions and finite element (FE) simulations often rely heavily on MV data for TV applications, despite fundamentally different mechanical and physiological environments. METHOD/RESULTS To bridge this gap, we performed a rigorous mechanical, morphological, and microstructural characterization of the MV and TV leaflets and chordae in a porcine model. Planar biaxial testing, uniaxial testing, second harmonic generation imaging and Verhoeff Van Gieson staining were performed. Morphological parameters, tissue moduli, extensibility, and anisotropy were quantified and compared. No major differences in leaflet mechanics or structure were found between TV and MV; chordal mechanics, morphology, and structure were found to compensate for anatomical and physiological loading differences between the valves. No differences in chordal mechanics were observed by insertion point within a leaflet; the septal tricuspid leaflet (STL) and posterior mitral leaflet (PML) did not have distinguishable strut chords, and the STL had the shortest chords. Within a valve, chords from septally-located leaflets were more extensible. MV chords were stiffer. CONCLUSIONS This study presents the first rigorous comparative mechanical and structural dataset of MV and TV structures. Valve type and anatomical location may be stronger predictors of chordal mechanics. Chords from septally-located leaflets differ from each other and from their intravalvular counterparts; they merit special consideration in surgical and computational applications. STATEMENT OF SIGNIFICANCE A better understanding of the tricuspid valve (TV) and its associated structures is important for making advancements towards the repair of tricuspid regurgitation. Mitral valve structures have been extensively studied, but little is known about the TV and right-sided heart diseases. Clinical decisions and computational simulations often rely heavily on MV data for TV applications, despite fundamentally different environments. We therefore performed a rigorous mechanical, morphological, and microstructural characterization of atrioventricular leaflets and chordae tendineae in a porcine model. Finding that valve type and anatomical location may be strong predictors of chordal mechanics, chords from septally-located leaflets differ from each other and from their intravalvular counterparts; they merit special consideration in surgical and computational applications.
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Quantification and comparison of the mechanical properties of four human cardiac valves. Acta Biomater 2017; 54:345-355. [PMID: 28336153 DOI: 10.1016/j.actbio.2017.03.026] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 02/21/2017] [Accepted: 03/16/2017] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Although having the same ability to permit unidirectional flow within the heart, the four main valves-the mitral valve (MV), aortic (AV), tricuspid (TV) and pulmonary (PV) valves-experience different loading conditions; thus, they exhibit different structural integrity from one another. Most research on heart valve mechanics have been conducted mainly on MV and AV or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same aged patient population whose death was unrelated to cardiovascular disease. METHODS A total of 114 valve leaflet samples were excised from 12 human cadavers whose death was unrelated to cardiovascular disease (70.1±3.7years old). Tissue mechanical and structural properties were characterized by planar biaxial mechanical testing and histological methods. The experimental data were then fitted with a Fung-type constitutive model. RESULTS The four valves differed substantially in thickness, degree of anisotropy, and stiffness. The leaflets of the left heart (the AV leaflets and the anterior mitral leaflets, AML) were significantly stiffer and less compliant than their counterparts in the right heart. TV leaflets were the most extensible and isotropic, while AML and AV leaflets were the least extensible and the most anisotropic. Age plays a significant role in the reduction of leaflet stiffness and extensibility with nearly straightened collagen fibers observed in the leaflet samples from elderly groups (65years and older). CONCLUSIONS Results from 114 human leaflet samples not only provided a baseline quantification of the mechanical properties of aged human cardiac valves, but also offered a better understanding of the age-dependent differences among the four valves. It is hoped that the experimental data collected and the associated constitutive models in this study can facilitate future studies of valve diseases, treatments and the development of interventional devices. STATEMENT OF SIGNIFICANCE Most research on heart valve mechanics have been conducted mainly on mitral and aortic valves or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same relatively healthy elderly patient population. In this study, the mechanical and microstructural properties of 114 leaflets of aortic, mitral, pulmonary and tricuspid valves from 12 human cadaver hearts were mechanically tested, analyzed and compared. Our results not only provided a baseline quantification of the mechanical properties of aged human valves, but a age range between patients (51-87years) also offers a better understanding of the age-dependent differences among the four valves. It is hoped that the obtained experimental data and associated constitutive parameters can facilitate studies of valve diseases, treatments and the development of interventional devices.
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10
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Sierad LN, Shaw EL, Bina A, Brazile B, Rierson N, Patnaik SS, Kennamer A, Odum R, Cotoi O, Terezia P, Branzaniuc K, Smallwood H, Deac R, Egyed I, Pavai Z, Szanto A, Harceaga L, Suciu H, Raicea V, Olah P, Simionescu A, Liao J, Movileanu I, Harpa M, Simionescu DT. Functional Heart Valve Scaffolds Obtained by Complete Decellularization of Porcine Aortic Roots in a Novel Differential Pressure Gradient Perfusion System. Tissue Eng Part C Methods 2016; 21:1284-96. [PMID: 26467108 DOI: 10.1089/ten.tec.2015.0170] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There is a great need for living valve replacements for patients of all ages. Such constructs could be built by tissue engineering, with perspective of the unique structure and biology of the aortic root. The aortic valve root is composed of several different tissues, and careful structural and functional consideration has to be given to each segment and component. Previous work has shown that immersion techniques are inadequate for whole-root decellularization, with the aortic wall segment being particularly resistant to decellularization. The aim of this study was to develop a differential pressure gradient perfusion system capable of being rigorous enough to decellularize the aortic root wall while gentle enough to preserve the integrity of the cusps. Fresh porcine aortic roots have been subjected to various regimens of perfusion decellularization using detergents and enzymes and results compared to immersion decellularized roots. Success criteria for evaluation of each root segment (cusp, muscle, sinus, wall) for decellularization completeness, tissue integrity, and valve functionality were defined using complementary methods of cell analysis (histology with nuclear and matrix stains and DNA analysis), biomechanics (biaxial and bending tests), and physiologic heart valve bioreactor testing (with advanced image analysis of open-close cycles and geometric orifice area measurement). Fully acellular porcine roots treated with the optimized method exhibited preserved macroscopic structures and microscopic matrix components, which translated into conserved anisotropic mechanical properties, including bending and excellent valve functionality when tested in aortic flow and pressure conditions. This study highlighted the importance of (1) adapting decellularization methods to specific target tissues, (2) combining several methods of cell analysis compared to relying solely on histology, (3) developing relevant valve-specific mechanical tests, and (4) in vitro testing of valve functionality.
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Affiliation(s)
- Leslie Neil Sierad
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Eliza Laine Shaw
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Alexander Bina
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Bryn Brazile
- 2 Tissue Bioengineering Laboratory, Department of Agricultural and Biological Engineering, Mississippi State University , Starkville, Mississippi
| | - Nicholas Rierson
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Sourav S Patnaik
- 2 Tissue Bioengineering Laboratory, Department of Agricultural and Biological Engineering, Mississippi State University , Starkville, Mississippi
| | - Allison Kennamer
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Rebekah Odum
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Ovidiu Cotoi
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Preda Terezia
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Klara Branzaniuc
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Harrison Smallwood
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Radu Deac
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Imre Egyed
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Zoltan Pavai
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Annamaria Szanto
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Lucian Harceaga
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Horatiu Suciu
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Victor Raicea
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Peter Olah
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Agneta Simionescu
- 4 Cardiovascular Tissue Engineering and Regenerative Medicine Laboratory, Department of Bioengineering, Clemson University , Clemson, South Carolina
| | - Jun Liao
- 2 Tissue Bioengineering Laboratory, Department of Agricultural and Biological Engineering, Mississippi State University , Starkville, Mississippi
| | - Ionela Movileanu
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Marius Harpa
- 3 Tissue Engineering and Regenerative Medicine Laboratory, Department of Anatomy, University of Medicine and Pharmacy , Targu Mures, Romania
| | - Dan Teodor Simionescu
- 1 Biocompatibility and Tissue Regeneration Laboratories, Department of Bioengineering, Clemson University , Clemson, South Carolina
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