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Modelling the rate-dependency of the mechanical behaviour of the aortic heart valve: An experimentally guided theoretical framework. J Mech Behav Biomed Mater 2022; 134:105341. [DOI: 10.1016/j.jmbbm.2022.105341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/30/2022] [Accepted: 06/26/2022] [Indexed: 11/19/2022]
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Noble C, Morse D, Lerman A, Young M. Evaluation of Pericardial Tissues from Assorted Species as a Tissue-Engineered Heart Valve Material. Med Biol Eng Comput 2022; 60:393-406. [PMID: 34984601 DOI: 10.1007/s11517-021-02498-5] [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: 09/13/2021] [Accepted: 12/17/2021] [Indexed: 11/25/2022]
Abstract
Decellularized pericardial tissue is a strong candidate for a TEHV material as ECM is present to guide cellular infiltration and fixed porcine and bovine pericardial tissue have existing use in bioprosthetic heart valves. In this work, we compare the mechanical and microstructural properties of decellularized-sterilized (DS) porcine, bovine, and bison pericardial tissues with respect to use as a TEHV. H&E staining was used to verify removal of cellular content post-decellularization and to evaluate collagen fiber structure. Additionally, uniaxial and biaxial tension testing were used to compare mechanical performance and, for the latter, acquire constitutive model parameters for subsequent finite element (FE) modeling. H&E staining revealed complete removal of cellular content and good collagen fiber structure. Tensile testing showed comparable mechanical strength between the three DS pericardial tissues and considerably stronger mechanical properties compared to native tissues. Bovine and bison DS pericardial tissues showed the strongest mechanical performance in the FE models with bison demonstrating the overall best mechanical characteristics. The increased thickness of bovine and bison tissues coupled with the strong mechanical behavior and ECM structure indicates that these materials will be resistant to damage until sufficient cellular infiltration has occurred such that damaged tissue can be repaired.
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Affiliation(s)
- Christopher Noble
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - David Morse
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Amir Lerman
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Melissa Young
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
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Noble C, Kamykowski M, Lerman A, Young M. Rate-Dependent and Relaxation Properties of Porcine Aortic Heart Valve Biomaterials. IEEE OPEN JOURNAL OF ENGINEERING IN MEDICINE AND BIOLOGY 2020; 1:197-202. [PMID: 33748767 PMCID: PMC7971416 DOI: 10.1109/ojemb.2020.3002450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Objective: This work evaluates the rate-dependent and relaxation properties of native porcine heart valves, glutaraldehyde fixed porcine pericardium, and decellularized sterilized porcine pericardium. Methods: Biaxial tension testing was performed at strain-rates of 0.001 s−1, 0.01 s−1, 0.1 s−1, and 1 s−1. Finally, relaxation testing for 300 s was performed on all heart valve biomaterials. Results: No notable rate-dependent response was observed for any of the three biomaterials with few significant differences between any strain-rates. For relaxation testing, native tissues showed the most pronounced drop in stress and glutaraldehyde the lowest drop in stress although no tissues showed anisotropy in the relaxation. Conclusions: Increasing the strain-rate of the three biomaterials considered does not increase the stress within the tissue. This indicates that there will not be increased fatigue from accelerated wear testing compared to loading at physiological strain-rates as the increase strain-rates would likely not significantly alter the tissue stress.
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Affiliation(s)
- Christopher Noble
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55905 USA
| | - Michael Kamykowski
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55905 USA
| | - Amir Lerman
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55905 USA
| | - Melissa Young
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55905 USA
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Anssari-Benam A, Tseng YT, Holzapfel GA, Bucchi A. Rate-dependent mechanical behaviour of semilunar valves under biaxial deformation: From quasi-static to physiological loading rates. J Mech Behav Biomed Mater 2020; 104:103645. [PMID: 32174403 DOI: 10.1016/j.jmbbm.2020.103645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 11/29/2022]
Abstract
In this study we investigate the rate-dependency of the mechanical behaviour of semilunar heart valves under biaxial deformation, from quasi-static to physiological loading rates. This work extends and complements our previous undertaking, where the rate-dependency in the mechanical behaviour of semilunar valve specimens was documented in sub-physiological rate domains (Acta Biomater. 2019; https://doi.org/10.1016/j.actbio.2019.02.008). For the first time we demonstrate herein that the stress-stretch curves obtained from specimens under physiological rates too are markedly different to those at sufficiently lower rates and at quasi-static conditions. The results importantly underline that the mechanical behaviour of semilunar heart valves is rate dependent, and the physiological mechanical behaviour of the valves may not be correctly obtained via material characterisation tests at arbitrary low deformation rates. Presented results in this work provide an inclusive dataset for material characterisation and modelling of semilunar heart valves across a 10,000 fold deformation rate, both under equi-biaxial and 1:3 ratio deformation rates. The important application of these results is to inform the development of appropriate mechanical testing protocols, as well as devising new models, for suitable determination of the rate-dependent constitutive mechanical behaviour of the semilunar valves.
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Affiliation(s)
- Afshin Anssari-Benam
- Cardiovascular Engineering Research Laboratory (CERL), School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Road, Portsmouth, PO1 3DJ, United Kingdom.
| | - Yuan-Tsan Tseng
- National Heart and Lung Institute, Heart Science Centre, Imperial College London, Middlesex, United Kingdom
| | - Gerhard A Holzapfel
- Graz University of Technology, Institute of Biomechanics, Graz, Austria; Norwegian University of Science and Technology (NTNU), Department of Structural Engineering, Trondheim, Norway
| | - Andrea Bucchi
- Cardiovascular Engineering Research Laboratory (CERL), School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Road, Portsmouth, PO1 3DJ, United Kingdom
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Li RL, Russ J, Paschalides C, Ferrari G, Waisman H, Kysar JW, Kalfa D. Mechanical considerations for polymeric heart valve development: Biomechanics, materials, design and manufacturing. Biomaterials 2019; 225:119493. [PMID: 31569017 PMCID: PMC6948849 DOI: 10.1016/j.biomaterials.2019.119493] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/21/2019] [Accepted: 09/11/2019] [Indexed: 01/12/2023]
Abstract
The native human heart valve leaflet contains a layered microstructure comprising a hierarchical arrangement of collagen, elastin, proteoglycans and various cell types. Here, we review the various experimental methods that have been employed to probe this intricate microstructure and which attempt to elucidate the mechanisms that govern the leaflet's mechanical properties. These methods include uniaxial, biaxial, and flexural tests, coupled with microstructural characterization techniques such as small angle X-ray scattering (SAXS), small angle light scattering (SALS), and polarized light microscopy. These experiments have revealed complex elastic and viscoelastic mechanisms that are highly directional and dependent upon loading conditions and biochemistry. Of all engineering materials, polymers and polymer-based composites are best able to mimic the tissue-level mechanical behavior of the native leaflet. This similarity to native tissue permits the fabrication of polymeric valves with physiological flow patterns, reducing the risk of thrombosis compared to mechanical valves and in some cases surpassing the in vivo durability of bioprosthetic valves. Earlier work on polymeric valves simply assumed the mechanical properties of the polymer material to be linear elastic, while more recent studies have considered the full hyperelastic stress-strain response. These material models have been incorporated into computational models for the optimization of valve geometry, with the goal of minimizing internal stresses and improving durability. The latter portion of this review recounts these developments in polymeric heart valves, with a focus on mechanical testing of polymers, valve geometry, and manufacturing methods.
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Affiliation(s)
- Richard L Li
- Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA; Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children's Hospital, Columbia University Medical Center, New York, NY, USA
| | - Jonathan Russ
- Department of Civil Engineering and Engineering Mechanics, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA
| | - Costas Paschalides
- Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA
| | - Giovanni Ferrari
- Department of Surgery and Biomedical Engineering, Columbia University Medical Center, New York, NY, USA
| | - Haim Waisman
- Department of Civil Engineering and Engineering Mechanics, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA
| | - Jeffrey W Kysar
- Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA; Department of Otolaryngology - Head and Neck Surgery, Columbia University Medical Center, New York, NY, USA.
| | - David Kalfa
- Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children's Hospital, Columbia University Medical Center, New York, NY, USA.
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Kramer KE, Ross CJ, Laurence DW, Babu AR, Wu Y, Towner RA, Mir A, Burkhart HM, Holzapfel GA, Lee CH. An investigation of layer-specific tissue biomechanics of porcine atrioventricular valve anterior leaflets. Acta Biomater 2019; 96:368-384. [PMID: 31260822 PMCID: PMC6717680 DOI: 10.1016/j.actbio.2019.06.049] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 06/24/2019] [Accepted: 06/26/2019] [Indexed: 12/29/2022]
Abstract
Atrioventricular heart valves (AHVs) are composed of structurally complex and morphologically heterogeneous leaflets. The coaptation of these leaflets during the cardiac cycle facilitates unidirectional blood flow. Valve regurgitation is treated preferably by surgical repair if possible or replacement based on the disease state of the valve tissue. A comprehensive understanding of valvular morphology and mechanical properties is crucial to refining computational models, serving as a patient-specific diagnostic and surgical tool for preoperative planning. Previous studies have modeled the stress distribution throughout the leaflet's thickness, but validations with layer-specific biaxial mechanical experiments are missing. In this study, we sought to fill this gap in literature by investigating the impact of microstructure constituents on mechanical behavior throughout the thickness of the AHVs' anterior leaflets. Porcine mitral valve anterior leaflets (MVAL) and tricuspid valve anterior leaflets (TVAL) were micro-dissected into three layers (atrialis/spongiosa, fibrosa, and ventricular) and two layers (atrialis/spongiosa and fibrosa/ventricularis), respectively, based on their relative distributions of extracellular matrix components as quantified by histological analyses: collagen, elastin, and glycosaminoglycans. Our results suggest that (i) for both valves, the atrialis/spongiosa layer is the most extensible and anisotropic layer, possibly due to its relatively low collagen content as compared to other layers, (ii) the intact TVAL response is stiffer than the atrialis/spongiosa layer but more compliant than the fibrosa/ventricularis layer, and (iii) the MVAL fibrosa and ventricularis layers behave nearly isotropic. These novel findings emphasize the biomechanical variances throughout the AHV leaflets, and our results could better inform future AHV computational model developments. STATEMENT OF SIGNIFICANCE: This study, which is the first of its kind for atrioventricular heart valve (AHV) leaflet tissue layers, rendered a mechanical characterization of the biaxial mechanical properties and distributions of extracellular matrix components (collagen, elastin, and glycosaminoglycans) of the mitral and tricuspid valve anterior leaflet layers. The novel findings from the present study emphasize the biomechanical variances throughout the thickness of AHV leaflets, and our results indicate that the previously-adopted homogenous leaflet in the AHV biomechanical modeling may be an oversimplification of the complex leaflet anatomy. Such improvement in the understanding of valvular morphology and tissue mechanics is crucial to future refinement of AHV computational models, serving as a patient-specific diagnostic and surgical tool, at the preoperative stage, for treating valvular heart diseases.
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Affiliation(s)
- Katherine E Kramer
- 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
| | - Devin W Laurence
- 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
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Rheal A Towner
- Advanced Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria; Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - 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, The University of Oklahoma, Norman, OK 73019, USA.
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Anssari-Benam A, Screen HR, Bucchi A. Insights into the micromechanics of stress-relaxation and creep behaviours in the aortic valve. J Mech Behav Biomed Mater 2019; 93:230-245. [DOI: 10.1016/j.jmbbm.2019.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 10/30/2018] [Accepted: 02/11/2019] [Indexed: 12/20/2022]
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Anssari-Benam A, Tseng YT, Holzapfel GA, Bucchi A. Rate-dependency of the mechanical behaviour of semilunar heart valves under biaxial deformation. Acta Biomater 2019; 88:120-130. [DOI: 10.1016/j.actbio.2019.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/25/2019] [Accepted: 02/08/2019] [Indexed: 12/23/2022]
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Noble C, Choe J, Uthamaraj S, Deherrera M, Lerman A, Young M. In Silico Performance of a Recellularized Tissue Engineered Transcatheter Aortic Valve. J Biomech Eng 2019; 141:61004-6100412. [PMID: 30874717 DOI: 10.1115/1.4043209] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Indexed: 01/04/2023]
Abstract
Commercially available heart valves have many limitations, such as a lack of re-modeling, risk of calcification and thromboembolic problems. Many state-of-the-art tissue engineered heart valves rely on recellularization. Current in vitro testing is insufficient in characterizing a soon to be living valve. It is imperative to understand the performance of an in situ valve, but due to the complex in vivo environment this is difficult to accomplish. Finite element analysis has become a standard tool for modeling mechanical behavior of heart valves; yet, research to date has mostly focused on commercial valves. The purpose of this study has been to develop finite element models of a decellularized and recellularized tissue engineered heart valve. Mechanical properties from porcine aortic valves were utilized to develop finite element models, which were run through a full physiological cardiac cycle. Maximum principal stresses and strains from the leaflets and commissures were analyzed. The results of this study demonstrate that the explanted tissues had reduced mechanical strength compared to the implants but were similar to the native tissues. For the finite element models the explanted recellularized leaflets showed lower stress but increased compliance in the leaflet belly compared to native tissues and higher compliance than implant tissues. Histology demonstrated recellularization and remodeling although remodeled collagen had no clear directionality. In conclusion, we observed successful recellularization and remodeling of the tissue, however, the mechanical response indicates the further remodeling is required following implantation in the aortic/pulmonary position.
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Affiliation(s)
- Christopher Noble
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Joshua Choe
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | | | - Milton Deherrera
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Amir Lerman
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Melissa Young
- Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, USA 55905, phone: +1 (507)-266-5120
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