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Emu ME, Hatami-Marbini H. Planar biaxial testing of CXL strengthening effects. Exp Eye Res 2024; 246:110005. [PMID: 39032624 DOI: 10.1016/j.exer.2024.110005] [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: 04/17/2024] [Revised: 06/07/2024] [Accepted: 07/12/2024] [Indexed: 07/23/2024]
Abstract
The stiffening effect of corneal crosslinking (CXL) treatment, a therapeutic approach for managing the progression of keratoconus, has been primarily investigated using uniaxial tensile experiments. However, this testing technique has several drawbacks and is unable to measure the mechanical response of cornea under a multiaxial loading state. In this work, we used biaxial mechanical testing method to characterize biomechanical properties of porcine cornea before and after CXL treatment. We also investigated the influence of preconditioning on measured properties and used TEM images to determine microstructural characteristics of the extracellular matrix. The conventional method of CXL treatment was used for crosslinking the porcine cornea. The biaxial experiments were done by an ElectroForce TestBench system at a stretch ratio of 1:1 and a displacement rate of 2 mm/min with and without preconditioning. The experimental measurements showed no significant difference in the mechanical properties of porcine cornea along the nasal temporal (NT) and superior inferior (SI) direction. Furthermore, the CXL therapy significantly enhanced the mechanical properties along both directions without creating anisotropic response. The samples tested with preconditioning showed significantly stiffer response than those tested without preconditioning. The TEM images showed that the CXL therapy did not increase the diameter of collagen fibers but significantly decreased their interfibrillar spacing, consistent with the mechanical property improvement of CXL treated samples.
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Affiliation(s)
- Md Esharuzzaman Emu
- Mechanical and Industrial Engineering Department, University of Illinois Chicago, Chicago, IL, USA
| | - Hamed Hatami-Marbini
- Mechanical and Industrial Engineering Department, University of Illinois Chicago, Chicago, IL, USA.
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2
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Faza NN, Harb SC, Wang DD, van den Dorpel MMP, Van Mieghem N, Little SH. Physical and Computational Modeling for Transcatheter Structural Heart Interventions. JACC Cardiovasc Imaging 2024; 17:428-440. [PMID: 38569793 DOI: 10.1016/j.jcmg.2024.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 04/05/2024]
Abstract
Structural heart disease interventions rely heavily on preprocedural planning and simulation to improve procedural outcomes and predict and prevent potential procedural complications. Modeling technologies, namely 3-dimensional (3D) printing and computational modeling, are nowadays increasingly used to predict the interaction between cardiac anatomy and implantable devices. Such models play a role in patient education, operator training, procedural simulation, and appropriate device selection. However, current modeling is often limited by the replication of a single static configuration within a dynamic cardiac cycle. Recognizing that health systems may face technical and economic limitations to the creation of "in-house" 3D-printed models, structural heart teams are pivoting to the use of computational software for modeling purposes.
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Affiliation(s)
- Nadeen N Faza
- Houston Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA
| | | | | | | | | | - Stephen H Little
- Houston Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA.
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3
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Kara R, Vergara C. Assessing turbulent effects in ascending aorta in presence of bicuspid aortic valve. Comput Methods Biomech Biomed Engin 2023:1-13. [PMID: 37950490 DOI: 10.1080/10255842.2023.2279938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023]
Abstract
Aortic valves with bicuspids have two rather than three leaflets, which is a congenital heart condition. About 0.5-2% of people have a bicuspid aortic valve. Blood flow through the aorta is commonly believed to be laminar, although aortic valve disorders can cause turbulent transitions. Understanding the impact of turbulence is crucial for foreseeing how the disease will progress. The study's objective was use large eddy simulation to provide a thorough analysis of the turbulence in bicuspid aortic valve dysfunction. Using a large eddy simulation, the blood flow patterns of the bicuspid and tricuspid aortic valves were compared, and significant discrepancies were found. The velocity field in flow in bicuspid configurations was asymmetrically distributed toward the ascending aorta. In tricuspid aortic valve (TAV) the flow, on the other hand, was symmetrical within the same aortic segment. Moreover, we looked into standard deviation, Q-criterion, viscosity ratio and wall shear stresses for each cases to understand transition to turbulence. Our findings indicate that in the bicuspid aortic valve (BAV) case, the fluid-dynamic abnormalities increase. The global turbulent kinetic energy and time-averaged wall shear stress for the TAV and BAV scenarios were also examined. We discovered that the global turbulent kinetic energy was higher in the BAV case compared to TAV, in addition to the increased wall shear stress induced by the BAV in the ascending aorta.
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Affiliation(s)
- Rukiye Kara
- Department of Mathematics, Mimar Sinan Fine Arts University, Istanbul, Turkey
| | - Christian Vergara
- LABS - Dipartimento di Chimica, Materiali e Ingegneria Chimica" Giulio Natta" - Politecnico di Milano, Milan, Italy
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4
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Simonian NT, Liu H, Vakamudi S, Pirwitz MJ, Pouch AM, Gorman JH, Gorman RC, Sacks MS. Patient-Specific Quantitative In-Vivo Assessment of Human Mitral Valve Leaflet Strain Before and After MitraClip Repair. Cardiovasc Eng Technol 2023; 14:677-693. [PMID: 37670097 DOI: 10.1007/s13239-023-00680-4] [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: 07/20/2022] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
PURPOSE Mitral regurgitation (MR) is a highly prevalent and deadly cardiac disease characterized by improper mitral valve (MV) leaflet coaptation. Among the plethora of available treatment strategies, the MitraClip is an especially safe option, but optimizing its long-term efficacy remains an urgent challenge. METHODS We applied our noninvasive image-based strain computation pipeline [1] to intraoperative transesophageal echocardiography datasets taken from ten patients undergoing MitraClip repair, spanning a range of MR etiologies and MitraClip configurations. We then analyzed MV leaflet strains before and after MitraClip implementation to develop a better understanding of (1) the pre-operative state of human regurgitant MV, and (2) the MitraClip's impact on the MV leaflet deformations. RESULTS The MV pre-operative strain fields were highly variable, underscoring both the heterogeneity of the MR in the patient population and the need for patient-specific treatment approaches. Similarly, there were no consistent overall post-operative strain patterns, although the average A2 segment radial strain difference between pre- and post-operative states was consistently positive. In contrast, the post-operative strain fields were better correlated to their respective pre-operative strain fields than to the inter-patient post-operative strain fields. This quantitative result implies that the patient specific pre-operative state of the MV guides its post-operative deformation, which suggests that the post-operative state can be predicted using pre-operative data-derived modelling alone. CONCLUSIONS The pre-operative MV leaflet strain patterns varied considerably across the range of MR disease states and after MitraClip repair. Despite large inter-patient heterogeneity, the post-operative deformation appears principally dictated by the pre-operative deformation state. This novel finding suggests that though the variation in MR functional state and MitraClip-induced deformation were substantial, the post-operative state can be predicted from the pre-operative data alone. This study suggests that, with use of larger patient cohort and corresponding long-term outcomes, quantitative predictive factors of MitraClip durability can be identified.
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Affiliation(s)
- Natalie T Simonian
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin , 201 East 24th St., Stop C0200, Austin, TX, 78712-1229, USA
| | - Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin , 201 East 24th St., Stop C0200, Austin, TX, 78712-1229, USA
| | - Sneha Vakamudi
- Ascension Texas Cardiovascular & Division of Cardiology, Department of Internal Medicine, Dell Medical School, University of Texas, Austin, TX, USA
| | - Mark J Pirwitz
- Ascension Texas Cardiovascular & Division of Cardiology, Department of Internal Medicine, Dell Medical School, University of Texas, Austin, TX, USA
| | - Alison M Pouch
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin , 201 East 24th St., Stop C0200, Austin, TX, 78712-1229, USA.
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5
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Feng X, Liu Y, Kamensky D, McComb DW, Breuer CK, Sacks MS. Functional mechanical behavior of the murine pulmonary heart valve. Sci Rep 2023; 13:12852. [PMID: 37553466 PMCID: PMC10409802 DOI: 10.1038/s41598-023-40158-w] [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] [Accepted: 08/05/2023] [Indexed: 08/10/2023] Open
Abstract
Genetically modified mouse models provide a versatile and efficient platform to extend our understanding of the underlying disease processes and evaluate potential treatments for congenital heart valve diseases. However, applications have been limited to the gene and molecular levels due to the small size of murine heart valves, which prohibits the use of standard mechanical evaluation and in vivo imaging methods. We have developed an integrated imaging/computational mechanics approach to evaluate, for the first time, the functional mechanical behavior of the murine pulmonary heart valve (mPV). We utilized extant mPV high resolution µCT images of 1-year-old healthy C57BL/6J mice, with mPVs loaded to 0, 10, 20 or 30 mmHg then chemically fixed to preserve their shape. Individual mPV leaflets and annular boundaries were segmented and key geometric quantities of interest defined and quantified. The resulting observed inter-valve variations were small and consistent at each TVP level. This allowed us to develop a high fidelity NURBS-based geometric model. From the resultant individual mPV geometries, we developed a mPV shape-evolving geometric model (SEGM) that accurately represented mPV shape changes as a continuous function of transvalvular pressure. The SEGM was then integrated into an isogeometric finite element based inverse model that estimated the individual leaflet and regional mPV mechanical behaviors. We demonstrated that the mPV leaflet mechanical behaviors were highly anisotropic and nonlinear, with substantial leaflet and regional variations. We also observed the presence of strong axial mechanical coupling, suggesting the important role of the underlying collagen fiber architecture in the mPV. When compared to larger mammalian species, the mPV exhibited substantially different mechanical behaviors. Thus, while qualitatively similar, the mPV exhibited important functional differences that will need to accounted for in murine heart valve studies. The results of this novel study will allow detailed murine tissue and organ level investigations of semi-lunar heart valve diseases.
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Affiliation(s)
- Xinzeng Feng
- Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Yifei Liu
- Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, OH, 43210, USA
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - David Kamensky
- Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA, 92093, USA
| | - David W McComb
- Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, OH, 43210, USA
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Christopher K Breuer
- Center for Regenerative Medicine, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA
- Department of Pediatric Surgery, Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Michael S Sacks
- Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA.
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
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6
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West TM, Howsmon DP, Massidda MW, Vo HN, Janobas AA, Baker AB, Sacks MS. The effects of strain history on aortic valve interstitial cell activation in a 3D hydrogel environment. APL Bioeng 2023; 7:026101. [PMID: 37035541 PMCID: PMC10076067 DOI: 10.1063/5.0138030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/13/2023] [Indexed: 04/05/2023] Open
Abstract
Aortic valves (AVs) undergo unique stretch histories that include high rates and magnitudes. While major differences in deformation patterns have been observed between normal and congenitally defective bicuspid aortic valves (BAVs), the relation to underlying mechanisms of rapid disease onset in BAV patients remains unknown. To evaluate how the variations in stretch history affect AV interstitial cell (AVIC) activation, high-throughput methods were developed to impart varied cyclical biaxial stretch histories into 3D poly(ethylene) glycol hydrogels seeded with AVICs for 48 h. Specifically, a physiologically mimicking stretch history was compared to two stretch histories with varied peak stretch and stretch rate. Post-conditioned AVICs were imaged for nuclear shape, alpha smooth muscle actin (αSMA) and vimentin (VMN) polymerization, and small mothers against decapentaplegic homologs 2 and 3 (SMAD 2/3) nuclear activity. The results indicated that bulk gel deformations were accurately transduced to the AVICs. Lower peak stretches lead to increased αSMA polymerization. In contrast, VMN polymerization was a function of stretch rate, with SMAD 2/3 nuclear localization and nuclear shape also trending toward stretch rate dependency. Lower than physiological levels of stretch rate led to higher SMAD 2/3 activity, higher VMN polymerization around the nucleus, and lower nuclear elongation. αSMA polymerization did not correlate with VMN polymerization, SMAD 2/3 activity, nor nuclear shape. These results suggest that a negative feedback loop may form between SMAD 2/3, VMN, and nuclear shape to maintain AVIC homeostatic nuclear deformations, which is dependent on stretch rate. These novel results suggest that AVIC mechanobiological responses are sensitive to stretch history and provide insight into the mechanisms of AV disease.
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Affiliation(s)
- Toni M. West
- James T. Willerson Center for Cardiovascular Modelling and Simulation, Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, Austin, Texas 78711, USA
| | - Daniel P. Howsmon
- James T. Willerson Center for Cardiovascular Modelling and Simulation, Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, Austin, Texas 78711, USA
| | - Miles W. Massidda
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78711, USA
| | | | | | - Aaron B. Baker
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78711, USA
| | - Michael S. Sacks
- James T. Willerson Center for Cardiovascular Modelling and Simulation, Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, Austin, Texas 78711, USA
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7
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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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8
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Tarraf SA, Kramer B, Vianna E, Gillespie C, Germano E, Emerton KB, Amini R, Colbrunn R, Hargrave J, Roselli EE, Bellini C. Lengthwise regional mechanics of the human aneurysmal ascending thoracic aorta. Acta Biomater 2023; 162:266-277. [PMID: 36944405 PMCID: PMC10148908 DOI: 10.1016/j.actbio.2023.03.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/16/2023] [Accepted: 03/15/2023] [Indexed: 03/23/2023]
Abstract
The prognosis of patients undergoing emergency endovascular repair of ascending thoracic aortic aneurysm (ATAA) depends on defect location, with root disease bearing worse outcomes than proximal or distal aortopathy. We speculate that a spatial gradient in aneurysmal tissue mechanics through the length of the ascending thoracic aorta may fuel noted survival discrepancies. To this end, we performed planar biaxial testing on 153 root, proximal, and distal segments of ATAA samples collected from 80 patients receiving elective open surgical repair. Following data averaging via surface fitting-based interpolation of strain-controlled protocols, we combined in-vitro and in-vivo measurements of loads and geometry to resolve inflation-extension kinematics and evaluate mechanical metrics of stress, stiffness, and energy at consistent deformation levels. Representative (averaged) experimental data and simulated in-vivo conditions revealed significantly larger biaxial stiffness at the root compared to either proximal or distal tissues, which persisted as the entire aorta stiffened during aging. Advancing age further reduced biaxial stretch and energy storage, a measure of aortic function, across all ATAA segments. Importantly, age emerged as a stronger predictor of tissue mechanics in ATAA disease than either bicuspid aortic valve or connective tissue disorders. Besides strengthening the general understanding of aneurysmal disease, our findings provide specifications to customize the design of stent-grafts for the treatment of ATAA disease. Optimization of deployment and interaction of novel endovascular devices with the local native environment is expected to carry significant potential for improving clinical outcomes. STATEMENT OF SIGNIFICANCE: Elucidating the lengthwise regional mechanics of ascending thoracic aortic aneurysms (ATAAs) is critical for the design of endovascular devices tailored to the ascending aorta. Stent-grafts provide a less invasive alternative to support the long-term survival of ATAA patients ineligible for open surgical repair. In this study, we developed a numerical framework that combines semi-inverse constitutive and forward modeling with in-vitro and in-vivo data to extract mechanical descriptors of ATAA tissue behavior at physiologically meaningful deformation. Moving distally from the aortic root to the first ascending aortic branch, we observed a progressive decline in biaxial stiffness. Furthermore, we showed that aging leads to reduced aortic function and is a stronger predictor of mechanics than either valve morphology or underlying syndromic disorder.
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Affiliation(s)
- Samar A Tarraf
- Department of Bioengineering, Northeastern University, 360 Huntington Ave., Boston, MA, 02125 USA
| | - Benjamin Kramer
- Aortic Center, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Emily Vianna
- Aortic Center, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Callan Gillespie
- Department of Biomedical Engineering, BioRobotics and Mechanical Testing Core, Cleveland Clinic, Cleveland, OH, USA
| | - Emídio Germano
- Aortic Center, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Kelly B Emerton
- Aortic Center, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Rouzbeh Amini
- Department of Bioengineering, Northeastern University, 360 Huntington Ave., Boston, MA, 02125 USA; Department of Mechanical and Industrial Engineering, Northeastern University, 360 Huntington Ave., Boston, MA, 02125 USA
| | - Robb Colbrunn
- Department of Biomedical Engineering, BioRobotics and Mechanical Testing Core, Cleveland Clinic, Cleveland, OH, USA
| | - Jennifer Hargrave
- Department of Cardiothoracic Anesthesiology, Cleveland Clinic, Cleveland, OH, USA
| | - Eric E Roselli
- Aortic Center, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, BioRobotics and Mechanical Testing Core, Cleveland Clinic, Cleveland, OH, USA
| | - Chiara Bellini
- Department of Bioengineering, Northeastern University, 360 Huntington Ave., Boston, MA, 02125 USA.
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9
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Gupta V, Gupta S, Chanda A. Development of an ultra-low-cost planar biaxial tester for soft tissue characterization. Biomed Phys Eng Express 2023; 9. [PMID: 36745909 DOI: 10.1088/2057-1976/acb940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/06/2023] [Indexed: 02/08/2023]
Abstract
Nowadays, the research in the arena of biomedical engineering or specifically soft tissue characterization is rapidly increasing. Due to the complex properties of soft tissues such as, anisotropy and viscoelasticity, it is difficult to predict the deformation behaviour. Hence, soft tissue characterization is essential to analyze these metrics. Soft tissue characterization, specifically, can be done by implementing a planar biaxial tester. Currently, available biaxial testers are mostly developed with respect to other mechanical components such as metals, and not for the soft tissues. Also, these devices are very costly, which makes it difficult for the low and middle income countries to perform this characterization. To solve this problem, in this work, an extremely low-cost biaxial tester was designed and developed. The design of the biaxial tester was simple and modular to allow device modifications according to the applications. The device has a force capability of less than 0.4 kN and a variable speed of 18 mm min-1to 300 mm min-1. The biaxial tester was validated using a standard test material with mechanical testing machine and was further tested on several wound geometries including circular, square, diamond shaped, L-Plasty, and elliptical. The developed fully automated device exhibited high accuracy with real-time monitoring. Furthermore, test results on the wounds showed the device's capability to differentiate amongst the considered wound geometries. This device can be helpful to medical students and doctors in understanding the mechanical behaviour of soft tissues during injury induced damage, disease, wounds healing and also for plethora of applications such as expansion testing of skin grafts.
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Affiliation(s)
- Vivek Gupta
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Shubham Gupta
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India.,Department of Biomedical Engineering, All India Institute of Medical Sciences (AIIMS), Delhi, India
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10
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Albert BJ, Butcher JT. Future prospects in the tissue engineering of heart valves: a focus on the role of stem cells. Expert Opin Biol Ther 2023; 23:553-564. [PMID: 37171790 PMCID: PMC10461076 DOI: 10.1080/14712598.2023.2214313] [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: 02/02/2023] [Accepted: 05/11/2023] [Indexed: 05/13/2023]
Abstract
INTRODUCTION Heart valve disease is a growing burden on the healthcare system. Current solutions are insufficient for young patients and do not offer relief from reintervention. Tissue engineered heart valves (TEHVs) offer a solution that grows and responds to the native environment in a similar way to a healthy valve. Stem cells hold potential to populate these valves as a malleable source that can adapt to environmental cues. AREAS COVERED This review covers current methods of recapitulating features of native heart valves with tissue engineering through use of stem cell populations with in situ and in vitro methods. EXPERT OPINION In the field of TEHVs, we see a variety of approaches in cell source, biomaterial, and maturation methods. Choosing appropriate cell populations may be very patient specific; consistency and predictability will be key to long-term success. In situ methods are closer to translation but struggle with consistent cellularization. In vitro culture requires specialized methods but may recapitulate native valve cell populations with higher fidelity. Understanding how cell populations react to valve conditions and immune response is vital for success. Detrimental valve pathologies have proven to be difficult to avoid in early translation attempts.
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Affiliation(s)
- Benjamin J Albert
- Cornell University, Meinig School of Biomedical Engineering, Ithaca, NY, USA
| | - Jonathan T Butcher
- Cornell University, Meinig School of Biomedical Engineering, Ithaca, NY, USA
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11
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Vernon MJ, Lu J, Padman B, Lamb C, Kent R, Mela P, Doyle B, Ihdayhid AR, Jansen S, Dilley RJ, De-Juan-Pardo EM. Engineering Heart Valve Interfaces Using Melt Electrowriting: Biomimetic Design Strategies from Multi-Modal Imaging. Adv Healthc Mater 2022; 11:e2201028. [PMID: 36300603 DOI: 10.1002/adhm.202201028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/12/2022] [Indexed: 01/28/2023]
Abstract
Interfaces within biological tissues not only connect different regions but also contribute to the overall functionality of the tissue. This is especially true in the case of the aortic heart valve. Here, melt electrowriting (MEW) is used to engineer complex, user-defined, interfaces for heart valve scaffolds. First, a multi-modal imaging investigation into the interfacial regions of the valve reveals differences in collagen orientation, density, and recruitment in previously unexplored regions including the commissure and inter-leaflet triangle. Overlapping, suturing, and continuous printing methods for interfacing MEW scaffolds are then investigated for their morphological, tensile, and flexural properties, demonstrating the superior performance of continuous interfaces. G-codes for MEW scaffolds with complex interfaces are designed and generated using a novel software and graphical user interface. Finally, a singular MEW scaffold for the interfacial region of the aortic heart valve is presented incorporating continuous interfaces, gradient porosities, variable layer numbers across regions, and tailored fiber orientations inspired by the collagen distribution and orientation from the multi-modal imaging study. The scaffold exhibits similar yield strain, hysteresis, and relaxation behavior to porcine heart valves. This work demonstrates the ability of a bioinspired approach for MEW scaffold design to address the functional complexity of biological tissues.
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Affiliation(s)
- Michael J Vernon
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Jason Lu
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Benjamin Padman
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, 6009, Australia
| | - Christopher Lamb
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Ross Kent
- Regenerative Medicine Program, CIMA, Universidad de Navarra, Pamplona, Navarra, 31008, Spain
| | - Petra Mela
- Medical Materials and Implants, Department of Mechanical Engineering, Munich Institute of Biomedical Engineering and TUM School of Engineering and Design, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany
| | - Barry Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia.,Australian Research Council Centre for Personalised Therapeutics Technologies, Australian Research Council, Parkville, ACT, 2609, Australia.,British Heart Foundation Centre of Cardiovascular Science, The University of Edinburgh, Edinburgh, EH1-3AT, UK
| | - Abdul Rahman Ihdayhid
- Department of Cardiology, Fiona Stanley Hospital, Perth, WA, 6150, Australia.,Curtin Medical School, Curtin University, Perth, WA, 6102, Australia
| | - Shirley Jansen
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,Curtin Medical School, Curtin University, Perth, WA, 6102, Australia.,Department of Vascular and Endovascular Surgery, Sir Charles Gairdner Hospital, Perth, WA, 6009, Australia.,Heart and Vascular Research Institute, Harry Perkins Institute of Medical Research, Perth, WA, 6009, Australia
| | - Rodney J Dilley
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Elena M De-Juan-Pardo
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
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12
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Wang B, Sierad LN, Mercuri JJ, Simionescu A, Simionescu DT, Williams LN, Vela R, Bajona P, Peltz M, Ramaswamy S, Hong Y, Liao J. Structural and biomechanical characterizations of acellular porcine mitral valve scaffolds: anterior leaflets, posterior leaflets, and chordae tendineae. ENGINEERED REGENERATION 2022; 3:374-386. [PMID: 38362305 PMCID: PMC10869114 DOI: 10.1016/j.engreg.2022.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mitral valve (MV) tissue engineering is still in its early stage, and one major challenge in MV tissue engineering is to identify appropriate scaffold materials. With the potential of acellular MV scaffolds being demonstrated recently, it is important to have a full understanding of the biomechanics of the native MV components and their acellular scaffolds. In this study, we have successfully characterized the structural and mechanical properties of porcine MV components, including anterior leaflet (AL), posterior leaflet (PL), strut chordae, and basal chordae, before and after decellularization. Quantitative DNA assay showed more than 90% reduction in DNA content, and Griffonia simplicifolia (GS) lectin immunohistochemistry confirmed the complete lack of porcine α-Gal antigen in the acellular MV components. In the acellular AL and PL, the atrialis, spongiosa, and fibrosa trilayered structure, along with its ECM constitutes, i.e., collagen fibers, elastin fibers, and portion of GAGs, were preserved. Nevertheless, the ECM of both AL and PL experienced a certain degree of disruption, exhibiting a less dense, porous ECM morphology. The overall anatomical morphology of the strut and basal chordae were also maintained after decellularization, with longitudinal morphology experiencing minimum disruption, but the cross-sectional morphology exhibiting evenly-distributed porous structure. In the acellular AL and PL, the nonlinear anisotropic biaxial mechanical behavior was overall preserved; however, uniaxial tensile tests showed that the removal of cellular content and the disruption of structural ECM did result in small decreases in maximum tensile modulus, tissue extensibility, failure stress, and failure strain for both MV leaflets and chordae.
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Affiliation(s)
- Bo Wang
- Joint Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, WI 53226, United States
| | - Leslie N. Sierad
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Jeremy J. Mercuri
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Agneta Simionescu
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Dan T. Simionescu
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Lakiesha N. Williams
- Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, United States
| | - Ryan Vela
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Pietro Bajona
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
- Allegheny Health Network-Drexel University College of Medicine, Pittsburgh, PA 15212, United States
| | - Matthias Peltz
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Sharan Ramaswamy
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, United States
| | - Yi Hong
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76010, United States
| | - Jun Liao
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76010, United States
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13
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Salim MT, Villa-Roel N, Vogel B, Jo H, Yoganathan AP. HIF1A inhibitor PX-478 reduces pathological stretch-induced calcification and collagen turnover in aortic valve. Front Cardiovasc Med 2022; 9:1002067. [PMID: 36419483 PMCID: PMC9676244 DOI: 10.3389/fcvm.2022.1002067] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 10/20/2022] [Indexed: 09/19/2023] Open
Abstract
HIF1A is significantly upregulated in calcified human aortic valves (AVs). Furthermore, HIF1A inhibitor PX-478 was shown to inhibit AV calcification under static and disturbed flow conditions. Since elevated stretch is one of the major mechanical stimuli for AV calcification, we investigated the effect of PX-478 on AV calcification and collagen turnover under a pathophysiological cyclic stretch (15%) condition. Porcine aortic valve (PAV) leaflets were cyclically (1 Hz) stretched at 15% for 24 days in osteogenic medium with or without PX-478. In addition, PAV leaflets were cyclically stretched at a physiological (10%) and 15% for 3 days in regular medium to assess its effect of on HIF1A mRNA expression. It was found that 100 μM (high concentration) PX-478 could significantly inhibit PAV calcification under 15% stretch, whereas 50 μM (moderate concentration) PX-478 showed a modest inhibitory effect on PAV calcification. Nonetheless, 50 μM PX-478 significantly reduced PAV collagen turnover under 15% stretch. Surprisingly, it was observed that cyclic stretch (15% vs. 10%) did not have any significant effect on HIF1A mRNA expression in PAV leaflets. These results suggest that HIF1A inhibitor PX-478 may impart its anti-calcific and anti-matrix remodeling effect in a stretch-independent manner.
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Affiliation(s)
- Md Tausif Salim
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Nicolas Villa-Roel
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | - Booth Vogel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, United States
| | - Hanjoong Jo
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | - Ajit P. Yoganathan
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, United States
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
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14
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Kaiser AD, Shad R, Schiavone N, Hiesinger W, Marsden AL. Controlled Comparison of Simulated Hemodynamics Across Tricuspid and Bicuspid Aortic Valves. Ann Biomed Eng 2022; 50:1053-1072. [PMID: 35748961 PMCID: PMC10775905 DOI: 10.1007/s10439-022-02983-4] [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: 10/13/2021] [Accepted: 05/16/2022] [Indexed: 11/01/2022]
Abstract
Bicuspid aortic valve is the most common congenital heart defect, affecting 1-2% of the global population. Patients with bicuspid valves frequently develop dilation and aneurysms of the ascending aorta. Both hemodynamic and genetic factors are believed to contribute to dilation, yet the precise mechanism underlying this progression remains under debate. Controlled comparisons of hemodynamics in patients with different forms of bicuspid valve disease are challenging because of confounding factors, and simulations offer the opportunity for direct and systematic comparisons. Using fluid-structure interaction simulations, we simulate flows through multiple aortic valve models in a patient-specific geometry. The aortic geometry is based on a healthy patient with no known aortic or valvular disease, which allows us to isolate the hemodynamic consequences of changes to the valve alone. Four fully-passive, elastic model valves are studied: a tricuspid valve and bicuspid valves with fusion of the left- and right-, right- and non-, and non- and left-coronary cusps. The resulting tricuspid flow is relatively uniform, with little secondary or reverse flow, and little to no pressure gradient across the valve. The bicuspid cases show localized jets of forward flow, excess streamwise momentum, elevated secondary and reverse flow, and clinically significant levels of stenosis. Localized high flow rates correspond to locations of dilation observed in patients, with the location related to which valve cusps are fused. Thus, the simulations support the hypothesis that chronic exposure to high local flow contributes to localized dilation and aneurysm formation.
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Affiliation(s)
- Alexander D Kaiser
- Institute for Computational & Mathematical Engineering, Stanford University, Stanford, CA, USA
- Department of Pediatrics (Cardiology), Stanford University, Stanford, CA, USA
- Stanford Cardiovascular Institute, Stanford, CA, USA
| | - Rohan Shad
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Nicole Schiavone
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - William Hiesinger
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Alison L Marsden
- Institute for Computational & Mathematical Engineering, Stanford University, Stanford, CA, USA.
- Department of Pediatrics (Cardiology), Stanford University, Stanford, CA, USA.
- Stanford Cardiovascular Institute, Stanford, CA, USA.
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
- Department of Bioengineering, Stanford University, Stanford, CA, USA.
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15
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Benchtop characterization of the tricuspid valve leaflet pre-strains. Acta Biomater 2022; 152:321-334. [PMID: 36041649 DOI: 10.1016/j.actbio.2022.08.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 08/01/2022] [Accepted: 08/22/2022] [Indexed: 11/21/2022]
Abstract
The pre-strains of biological soft tissues are important when relating their in vitro and in vivo mechanical behaviors. In this study, we present the first-of-its-kind experimental characterization of the tricuspid valve leaflet pre-strains. We use 3D photogrammetry and the reproducing kernel method to calculate the pre-strains within the central 10×10 mm region of the tricuspid valve leaflets from n=8 porcine hearts. In agreement with previous pre-strain studies for heart valve leaflets, our results show that all the three tricuspid valve leaflets shrink after explant from the ex vivo heart. These calculated strains are leaflet-specific and the septal leaflet experiences the most compressive changes. Furthermore, the strains observed after dissection of the central 10×10 mm region of the leaflet are smaller than when the valve is explanted, suggesting that our computed pre-strains are mainly due to the release of in situ annulus and chordae connections. The leaflets are then mounted on a biaxial testing device and preconditioned using force-controlled equibiaxial loading. We show that the employed preconditioning protocol does not 100% restore the leaflet pre-strains as removed during tissue dissection, and future studies are warranted to explore alternative preconditioning methods. Finally, we compare the calculated biomechanically oriented metrics considering five stress-free reference configurations. Interestingly, the radial tissue stretches and material anisotropies are significantly smaller compared to the post-preconditioning configuration. Extensions of this work can further explore the role of this unique leaflet-specific leaflet pre-strains on in vivo valve behavior via high-fidelity in-silico models.
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16
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Fitzpatrick DJ, Pham K, Ross CJ, Hudson LT, Laurence DW, Yu Y, Lee CH. Ex vivo experimental characterizations for understanding the interrelationship between tissue mechanics and collagen microstructure of porcine mitral valve leaflets. J Mech Behav Biomed Mater 2022; 134:105401. [DOI: 10.1016/j.jmbbm.2022.105401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/18/2022] [Accepted: 07/24/2022] [Indexed: 12/13/2022]
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17
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Pearce D, Nemcek M, Witzenburg C. Combining Unique Planar Biaxial Testing with Full-Field Thickness and Displacement Measurement for Spatial Characterization of Soft Tissues. Curr Protoc 2022; 2:e493. [PMID: 35849021 DOI: 10.1002/cpz1.493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Soft tissues rely on the incredible complexity of their microstructure for proper function. Local variations in material properties arise as tissues develop and adapt, often in response to changes in loading. A barrier to investigating the heterogeneous nature of soft tissues is the difficulty of developing experimental protocols and analysis tools that can accurately capture spatial variations in mechanical behavior. In this article, we detail protocols enabling mechanical characterizations of anisotropic, heterogeneous soft tissues or tissue analogs. We present a series of mechanical tests designed to maximize inhomogeneous strain fields and in-plane shear forces. A customized, 3D-printable gripping system reduces tissue handling and enhances shear. High-resolution imaging and laser micrometry capture full-field displacement and thickness, respectively. As the equipment necessary to conduct these protocols is commercially available, the experimental methods presented offer an accessible route toward addressing heterogeneity. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Unique biaxial testing of soft tissues and tissue analogs Basic Protocol 2: Full-field thickness measurement of soft tissues and tissue analogs Support Protocol 1: Creating and speckling cruciform-shaped samples for mechanical testing Support Protocol 2: Creating custom gripping system to minimize sample handling.
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Affiliation(s)
- Daniel Pearce
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Mark Nemcek
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Colleen Witzenburg
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin
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18
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Image Registration-Based Method for Reconstructing Transcatheter Heart Valve Geometry from Patient-Specific CT Scans. Ann Biomed Eng 2022; 50:805-815. [DOI: 10.1007/s10439-022-02962-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/30/2022] [Indexed: 01/18/2023]
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19
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Zhu C, Seo JH, Mittal R. Computational Modeling of Aortic Stenosis With a Reduced Degree-of-Freedom Fluid-Structure Interaction Valve Model. J Biomech Eng 2022; 144:1120773. [PMID: 34590694 DOI: 10.1115/1.4052576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Indexed: 11/08/2022]
Abstract
In this study, a novel reduced degree-of-freedom (rDOF) aortic valve model is employed to investigate the fluid-structure interaction (FSI) and hemodynamics associated with aortic stenosis. The dynamics of the valve leaflets are determined by an ordinary differential equation with two parameters and this rDOF model is shown to reproduce key features of more complex valve models. The hemodynamics associated with aortic stenosis is studied for three cases: a healthy case and two stenosed cases. The focus of the study is to correlate the hemodynamic features with the source generation mechanism of systolic murmurs associated with aortic stenosis. In the healthy case, extremely weak flow fluctuations are observed. However, in the stenosed cases, simulations show significant turbulent fluctuations in the ascending aorta, which are responsible for the generation of strong wall pressure fluctuations after the aortic root mostly during the deceleration phase of the systole. The intensity of the murmur generation increases with the severity of the stenosis, and the source locations for the two diseased cases studied here lie around 1.0 inlet duct diameters (Do) downstream of the ascending aorta.
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Affiliation(s)
- Chi Zhu
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Jung-Hee Seo
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Rajat Mittal
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218
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20
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Hermans LHL, Van Kelle MAJ, Oomen PJA, Lopata R.GP, Loerakker S, Bouten CVC. Scaffold Geometry-Imposed Anisotropic Mechanical Loading Guides the Evolution of the Mechanical State of Engineered Cardiovascular Tissues in vitro. Front Bioeng Biotechnol 2022; 10:796452. [PMID: 35252127 PMCID: PMC8888825 DOI: 10.3389/fbioe.2022.796452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
Cardiovascular tissue engineering is a promising approach to develop grafts that, in contrast to current replacement grafts, have the capacity to grow and remodel like native tissues. This approach largely depends on cell-driven tissue growth and remodeling, which are highly complex processes that are difficult to control inside the scaffolds used for tissue engineering. For several tissue engineering approaches, adverse tissue growth and remodeling outcomes were reported, such as aneurysm formation in vascular grafts, and leaflet retraction in heart valve grafts. It is increasingly recognized that the outcome of tissue growth and remodeling, either physiological or pathological, depends at least partly on the establishment of a homeostatic mechanical state, where one or more mechanical quantities in a tissue are maintained in equilibrium. To design long-term functioning tissue engineering strategies, understanding how scaffold parameters such as geometry affect the mechanical state of a construct, and how this state guides tissue growth and remodeling, is therefore crucial. Here, we studied how anisotropic versus isotropic mechanical loading—as imposed by initial scaffold geometry—influences tissue growth, remodeling, and the evolution of the mechanical state and geometry of tissue-engineered cardiovascular constructs in vitro. Using a custom-built bioreactor platform and nondestructive mechanical testing, we monitored the mechanical and geometric changes of elliptical and circular, vascular cell-seeded, polycaprolactone-bisurea scaffolds during 14 days of dynamic loading. The elliptical and circular scaffold geometries were designed using finite element analysis, to induce anisotropic and isotropic dynamic loading, respectively, with similar maximum stretch when cultured in the bioreactor platform. We found that the initial scaffold geometry-induced (an)isotropic loading of the engineered constructs differentially dictated the evolution of their mechanical state and geometry over time, as well as their final structural organization. These findings demonstrate that controlling the initial mechanical state of tissue-engineered constructs via scaffold geometry can be used to influence tissue growth and remodeling and determine tissue outcomes.
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Affiliation(s)
- L. H. L. Hermans
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
| | - M. A. J. Van Kelle
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
| | - P. J. A. Oomen
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
| | - R .G. P. Lopata
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | - S. Loerakker
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
- *Correspondence: S. Loerakker,
| | - C. V. C. Bouten
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
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21
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Middendorf JM, Ita ME, Winkelstein BA, H Barocas V. Local tissue heterogeneity may modulate neuronal responses via altered axon strain fields: insights about innervated joint capsules from a computational model. Biomech Model Mechanobiol 2021; 20:2269-2285. [PMID: 34514531 PMCID: PMC9289994 DOI: 10.1007/s10237-021-01506-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 08/12/2021] [Indexed: 02/08/2023]
Abstract
In innervated collagenous tissues, tissue scale loading may contribute to joint pain by transmitting force through collagen fibers to the embedded mechanosensitive axons. However, the highly heterogeneous collagen structures of native tissues make understanding this relationship challenging. Recently, collagen gels with embedded axons were stretched and the resulting axon signals were measured, but these experiments were unable to measure the local axon strain fields. Computational discrete fiber network models can directly determine axon strain fields due to tissue scale loading. Therefore, this study used a discrete fiber network model to identify how heterogeneous collagen networks (networks with multiple collagen fiber densities) change axon strain due to tissue scale loading. In this model, a composite cylinder (axon) was embedded in a Delaunay network (collagen). Homogeneous networks with a single collagen volume fraction and two types of heterogeneous networks with either a sparse center or dense center were created. Measurements of fiber forces show higher magnitude forces in sparse regions of heterogeneous networks and uniform force distributions in homogeneous networks. The average axon strain in the sparse center networks decreases when compared to homogeneous networks with similar collagen volume fractions. In dense center networks, the average axon strain increases compared to homogeneous networks. The top 1% of axon strains are unaffected by network heterogeneity. Based on these results, the interaction of tissue scale loading, collagen network heterogeneity, and axon strains in native musculoskeletal tissues should be considered when investigating the source of joint pain.
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Affiliation(s)
- Jill M Middendorf
- Department of Biomedical Engineering, College of Science and Engineering, University of Minnesota, Nils Hasselmo Hall, 312 Church St SE, Minneapolis, MN, USA
| | - Meagan E Ita
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Beth A Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Victor H Barocas
- Department of Biomedical Engineering, College of Science and Engineering, University of Minnesota, Nils Hasselmo Hall, 312 Church St SE, Minneapolis, MN, USA.
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22
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Kaiser AD, Shad R, Hiesinger W, Marsden AL. A design-based model of the aortic valve for fluid-structure interaction. Biomech Model Mechanobiol 2021; 20:2413-2435. [PMID: 34549354 PMCID: PMC10752438 DOI: 10.1007/s10237-021-01516-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 08/22/2021] [Indexed: 11/27/2022]
Abstract
This paper presents a new method for modeling the mechanics of the aortic valve and simulates its interaction with blood. As much as possible, the model construction is based on first principles, but such that the model is consistent with experimental observations. We require that tension in the leaflets must support a pressure, then derive a system of partial differential equations governing its mechanical equilibrium. The solution to these differential equations is referred to as the predicted loaded configuration; it includes the loaded leaflet geometry, fiber orientations and tensions needed to support the prescribed load. From this configuration, we derive a reference configuration and constitutive law. In fluid-structure interaction simulations with the immersed boundary method, the model seals reliably under physiological pressures and opens freely over multiple cardiac cycles. Further, model closure is robust to extreme hypo- and hypertensive pressures. Then, exploiting the unique features of this model construction, we conduct experiments on reference configurations, constitutive laws and gross morphology. These experiments suggest the following conclusions: (1) The loaded geometry, tensions and tangent moduli primarily determine model function. (2) Alterations to the reference configuration have little effect if the predicted loaded configuration is identical. (3) The leaflets must have sufficiently nonlinear material response to function over a variety of pressures. (4) Valve performance is highly sensitive to free edge length and leaflet height. These conclusions suggest appropriate gross morphology and material properties for the design of prosthetic aortic valves. In future studies, our aortic valve modeling framework can be used with patient-specific models of vascular or cardiac flow.
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Affiliation(s)
- Alexander D Kaiser
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.
- Department of Pediatrics (Cardiology), Stanford University, Stanford, CA, USA.
- Stanford Cardiovascular Institute, Stanford, CA, USA.
| | - Rohan Shad
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - William Hiesinger
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Alison L Marsden
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
- Department of Pediatrics (Cardiology), Stanford University, Stanford, CA, USA
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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23
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Hudson LT, Laurence DW, Lau HM, Mullins BT, Doan DD, Lee CH. Linking collagen fiber architecture to tissue-level biaxial mechanical behaviors of porcine semilunar heart valve cusps. J Mech Behav Biomed Mater 2021; 125:104907. [PMID: 34736023 DOI: 10.1016/j.jmbbm.2021.104907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 01/13/2023]
Abstract
The semilunar heart valves regulate the blood flow from the ventricles to the major arteries through the opening and closing of the scallop shaped cusps. These cusps are composed of collagen fibers that act as the primary loading-bearing component. The load-dependent collagen fiber architecture has been previously examined in the existing literature; however, these studies relied on chemical clearing and tissue modifications to observe the underlying changes in response to mechanical loads. In the present study, we address this gap in knowledge by quantifying the collagen fiber orientations and alignments of the aortic and pulmonary cusps through a multi-scale, non-destructive experimental approach. This opto-mechanical approach, which combines polarized spatial frequency domain imaging and biaxial mechanical testing, provides a greater field of view (10-25mm) and faster imaging time (45-50s) than other traditional collagen imaging techniques. The birefringent response of the collagen fibers was fit with a von Mises distribution, while the biaxial mechanical testing data was implemented into a modified full structural model for further analysis. Our results showed that the semilunar heart valve cusps are more extensible in the tissue's radial direction than the circumferential direction under all the varied biaxial testing protocols, together with greater material anisotropy among the pulmonary valve cusps compared to the aortic valve cusps. The collagen fibers were shown to reorient towards the direction of the greatest applied loading and incrementally realign with the increased applied stress. The collagen fiber architecture within the aortic valve cusps were found to be more homogeneous than the pulmonary valve counterparts, reflecting the differences in the physiological environments experienced by these two semilunar heart valves. Further, the von Mises distribution fitting highlighted the presence and contribution of two distinct fiber families for each of the two semilunar heart valves. The results from this work would provide valuable insight into connecting tissue-level mechanics to the underlying collagen fiber architecture-an essential information for the future development of high-fidelity aortic/pulmonary valve computational models.
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Affiliation(s)
- Luke T Hudson
- Biomechanics and Biomaterials Design Laboratory, The University of Oklahoma, Norman, OK, 73019, USA
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory, The University of Oklahoma, Norman, OK, 73019, USA
| | - Hunter M Lau
- Biomechanics and Biomaterials Design Laboratory, The University of Oklahoma, Norman, OK, 73019, USA
| | - Brennan T Mullins
- Biomechanics and Biomaterials Design Laboratory, The University of Oklahoma, Norman, OK, 73019, USA
| | - Deenna D Doan
- Biomechanics and Biomaterials Design Laboratory, The University of Oklahoma, Norman, OK, 73019, USA
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, The University of Oklahoma, Norman, OK, 73019, USA; Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, USA.
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24
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Johnson EL, Laurence DW, Xu F, Crisp CE, Mir A, Burkhart HM, Lee CH, Hsu MC. Parameterization, geometric modeling, and isogeometric analysis of tricuspid valves. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2021; 384:113960. [PMID: 34262232 PMCID: PMC8274564 DOI: 10.1016/j.cma.2021.113960] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Approximately 1.6 million patients in the United States are affected by tricuspid valve regurgitation, which occurs when the tricuspid valve does not close properly to prevent backward blood flow into the right atrium. Despite its critical role in proper cardiac function, the tricuspid valve has received limited research attention compared to the mitral and aortic valves on the left side of the heart. As a result, proper valvular function and the pathologies that may cause dysfunction remain poorly understood. To promote further investigations of the biomechanical behavior and response of the tricuspid valve, this work establishes a parameter-based approach that provides a template for tricuspid valve modeling and simulation. The proposed tricuspid valve parameterization presents a comprehensive description of the leaflets and the complex chordae tendineae for capturing the typical three-cusp structural deformation observed from medical data. This simulation framework develops a practical procedure for modeling tricuspid valves and offers a robust, flexible approach to analyze the performance and effectiveness of various valve configurations using isogeometric analysis. The proposed methods also establish a baseline to examine the tricuspid valve's structural deformation, perform future investigations of native valve configurations under healthy and disease conditions, and optimize prosthetic valve designs.
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Affiliation(s)
- Emily L. Johnson
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
| | - Devin W. Laurence
- School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Fei Xu
- Ansys Inc., 807 Las Cimas Parkway, Austin, Texas 78746, USA
| | - Caroline E. Crisp
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Harold M. Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Chung-Hao Lee
- School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, Oklahoma 73019, USA
- Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
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25
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Hou Q, Liu G, Liu N, Zhang H, Qu Z, Zhang H, Li H, Pan Y, Qiao A. Effect of Valve Height on the Opening and Closing Performance of the Aortic Valve Under Aortic Root Dilatation. Front Physiol 2021; 12:697502. [PMID: 34526908 PMCID: PMC8435789 DOI: 10.3389/fphys.2021.697502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/04/2021] [Indexed: 12/13/2022] Open
Abstract
Patients with aortic valve disease can suffer from valve insufficiency after valve repair surgery due to aortic root dilatation. The paper investigates the effect of valve height (Hv) on the aortic valve opening and closing in order to select the appropriate range of Hv for smoother blood flow through the aortic valve and valve closure completely in the case of continuous aortic root dilatation. A total of 20 parameterized three-dimensional models of the aortic root were constructed following clinical surgical guidance. Aortic annulus diameter (DAA) was separately set to 26, 27, 28, 29, and 30 mm to simulate aortic root dilatation. HV value was separately set to 13.5, 14, 14.5, and 15 mm to simulate aortic valve alterations in surgery. Time-varying pressure loads were applied to the valve, vessel wall of the ascending aorta, and left ventricle. Then, finite element analysis software was employed to simulate the movement and mechanics of the aortic root. The feasible design range of the valve size was evaluated using maximum stress, geometric orifice area (GOA), and leaflet contact force. The results show that the valve was incompletely closed when HV was 13.5 mm and DAA was 29 or 30 mm. The GOA of the valve was small when HV was 15 mm and DAA was 26 or 27 mm. The corresponding values of the other models were within the normal range. Compared with the model with an HV of 14 mm, the model with an HV of 14.5 mm could effectively reduce maximum stress and had relatively larger GOA and less change in contact force. As a result, valve height affects the performance of aortic valve opening and closing. Smaller HV is adapted to smaller DAA and vice versa. When HV is 14.5 mm, the valve is well adapted to the dilatation of the aortic root to enhance repair durability. Therefore, more attention should be paid to HV in surgical planning.
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Affiliation(s)
- Qianwen Hou
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Guimei Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Ning Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Honghui Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Zhuoran Qu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Hanbing Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Hui Li
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Youlian Pan
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Aike Qiao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
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26
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Campion G, Hershberger K, Whelan A, Conroy J, Lally C, Murphy BP. A Biomechanical and Microstructural Analysis of Bovine and Porcine Pericardium for Use in Bioprosthetic Heart Valves. STRUCTURAL HEART 2021. [DOI: 10.1080/24748706.2021.1938317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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27
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Ma N, Cheung DY, Butcher JT. Incorporating nanocrystalline cellulose into a multifunctional hydrogel for heart valve tissue engineering applications. J Biomed Mater Res A 2021; 110:76-91. [PMID: 34254733 DOI: 10.1002/jbm.a.37267] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/04/2021] [Accepted: 06/29/2021] [Indexed: 01/21/2023]
Abstract
Functional tissue engineered heart valves (TEHV) have been an elusive goal for nearly 30 years. Among the persistent challenges are the requirements for engineered valve leaflets that possess nonlinear elastic tissue biomechanical properties, support quiescent fibroblast phenotype, and resist osteogenic differentiation. Nanocellulose is an attractive tunable biological material that has not been employed to this application. In this study, we fabricated a series of photocrosslinkable composite hydrogels mNCC-MeGel (mNG) by conjugating TEMPO-modified nanocrystalline cellulose (mNCC) onto the backbone of methacrylated gelatin (MeGel). Their structures were characterized by FTIR, 1 HNMR and uniaxial compression testing. Human adipose-derived mesenchymal stem cells (HADMSC) were encapsulated within the material and evaluated for valve interstitial cell phenotypes over 14 days culture in both normal and osteogenic media. Compared to the MeGel control group, the HADMSC encapsulated within mNG showed decreased alpha smooth muscle actin (αSMA) expression and increased vimentin and aggrecan expression, suggesting the material supports a quiescent fibroblastic phenotype. Under osteogenic media conditions, HADMSC within mNG hydrogels showed lower expression of osteogenic genes, including Runx2 and osteocalcin, indicating resistance toward calcification. As a proof of principle, the mNG hydrogel, combined with a viscosity enhancing agent, was used to 3D bioprint a tall, self-standing tubular structure that sustained cell viability. Together, these results identify mNG as an attractive biomaterial for TEHV applications.
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Affiliation(s)
- Nianfang Ma
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA.,Institute of Bioengineering, Guangdong Academy of Sciences, Guangdong Provincial Engineering Technology Research Center of Biomaterials, Guangzhou, China
| | - Daniel Y Cheung
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Jonathan T Butcher
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
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28
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Shao Z, Tao T, Xu H, Chen C, Lee I, Chung S, Dong Z, Li W, Ma L, Bai H, Chen Q. Recent progress in biomaterials for heart valve replacement: Structure, function, and biomimetic design. VIEW 2021. [DOI: 10.1002/viw.20200142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Ziyu Shao
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine & Clinical Research Center for Oral Diseases of Zhejiang Province Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University Hangzhou 310006 China
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University Hangzhou China
| | - Tingting Tao
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Hongfei Xu
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Cen Chen
- College of Life Sciences and Medicine Zhejiang Sci‐Tech University Hangzhou China
| | - In‐Seop Lee
- College of Life Sciences and Medicine Zhejiang Sci‐Tech University Hangzhou China
- Institute of Natural Sciences Yonsei University Seoul Republic of Korea
| | - Sungmin Chung
- Biomaterials R&D Center GENOSS Co., Ltd. Suwon‐si Republic of Korea
| | - Zhihui Dong
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University Hangzhou China
| | - Weidong Li
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Liang Ma
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Hao Bai
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine & Clinical Research Center for Oral Diseases of Zhejiang Province Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University Hangzhou 310006 China
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University Hangzhou China
| | - Qianming Chen
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine & Clinical Research Center for Oral Diseases of Zhejiang Province Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University Hangzhou 310006 China
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29
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Yu H, Del Nido PJ, Geva T, Yang C, Wu Z, Rathod RH, Huang X, Billiar KL, Tang D. A Novel Pulmonary Valve Replacement Surgery Strategy Using Contracting Band for Patients With Repaired Tetralogy of Fallot: An MRI-Based Multipatient Modeling Study. Front Bioeng Biotechnol 2021; 9:638934. [PMID: 34095094 PMCID: PMC8170134 DOI: 10.3389/fbioe.2021.638934] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/08/2021] [Indexed: 11/21/2022] Open
Abstract
Patients with repaired Tetralogy of Fallot (ToF), a congenital heart defect which includes a ventricular septal defect and severe right ventricular outflow obstruction, account for the majority of cases with late-onset right ventricle (RV) failure. Current surgery procedures, including pulmonary valve replacement (PVR) with right ventricle remodeling, yield mixed results. PVR with active band insertion was hypothesized to be of clinical usage on improving RV function measured by ejection fraction (EF). In lieu of risky open-heart surgeries and experiments on animal and human, computational biomechanical models were adapted to study the impact of PVR with five band insertion options. Cardiac magnetic resonance (CMR) images were acquired from seven TOF patients before PVR surgery for model construction. For each patient, five different surgery plans combined with passive and active contraction band with contraction ratio of 20, 15, and 10% were studied. Those five plans include three single-band plans with different band locations; one plan with two bands, and one plan with three bands. Including the seven no-band models, 147 computational bi-ventricle models were constructed to simulate RV cardiac functions and identify optimal band plans. Patient variations with different band plans were investigated. Surgery plan with three active contraction bands and band active contraction ratio of 20% had the best performance on improving RV function. The mean ± SD RV ejection fraction value from the seven patients was 42.90 ± 5.68%, presenting a 4.19% absolute improvement or a 10.82% relative improvement, when compared with the baseline models (38.71 ± 5.73%, p = 0.016). The EF improvements from the seven patients varied from 2.87 to 6.01%. Surgical procedures using active contraction bands have great potential to improve RV function measured by ejection fraction for patients with repaired ToF. It is possible to have higher right ventricle ejection fraction improvement with more bands and higher band active contraction ratio. Our findings with computational models need to be further validated by animal experiments before clinical trial could become possible.
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Affiliation(s)
- Han Yu
- School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Pedro J Del Nido
- Department of Cardiac Surgery, Boston Children's Hospital, Boston, MA, United States.,Department of Surgery, Harvard Medical School, Boston, MA, United States
| | - Tal Geva
- Department of Cardiology, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Chun Yang
- Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Zheyang Wu
- Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Rahul H Rathod
- Department of Cardiology, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Xueying Huang
- School of Mathematical Sciences, Xiamen University, Xiamen, China
| | - Kristen L Billiar
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Dalin Tang
- School of Biological Science and Medical Engineering, Southeast University, Nanjing, China.,Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States
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30
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Nemchyna O, Knierim J, Dandel M, Solowjowa N, Schoenrath F, Unbehaun A, Kempfert J, Stein J, Knosalla C, Falk V, Soltani S. Feasibility of two-dimensional speckle-tracking echocardiography of aortic valve in patients with calcific aortic valve disease. J Biomech 2021; 122:110474. [PMID: 33940512 DOI: 10.1016/j.jbiomech.2021.110474] [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: 12/03/2020] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 11/28/2022]
Abstract
Calcific aortic valve (AV) disease is associated with increased stiffness and reduced motion of AV leaflets, has a progressive course, and can develop into aortic stenosis (AS). Our aim was to evaluate whether two-dimensional speckle-tracking echocardiography (STE) may be used for the assessment of AV stiffness. We applied STE to AV leaflets in patients with various degrees of degenerative changes of AV and measured strain as an absolute value of the radial deformation of AV leaflets. Deformation of AV expressed as averaged AV strain was greatest in patients with a normal AV (23.4 ± 6.4%), compared to those with aortic sclerosis (12.9 ± 3.2%), moderate-to-severe AS (11.9 ± 4%), and severe AS (10.9 ± 3.5%) (p < 0.01). A non-linear relationship and moderate correlation of AV strain with transvalvular hemodynamic parameters was observed. In patients with mild-to-moderate AS, the strain of AV leaflets also correlated negatively with AV calcification (r = -0.59, p = 0.008). Good inter-observer agreement was obtained for averaged AV strain with a coefficient of variation of 0.15 and an interclass correlation coefficient of 0.94 (p < 0.0001). In this study we demonstrated that deformation of AV leaflets as assessed by STE might be a potential method for a non-invasive evaluation of AV biomechanical properties and of the progression of calcific aortic disease. Further development of the two-dimensional speckle tracking technique specifically for valve structures is needed to enable a better quantification of leaflet deformation.
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Affiliation(s)
- Olena Nemchyna
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany.
| | - Jan Knierim
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany
| | | | - Natalia Solowjowa
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany
| | - Felix Schoenrath
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany
| | - Axel Unbehaun
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany
| | - Jörg Kempfert
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany; Department of Cardiothoracic Surgery, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julia Stein
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany
| | - Christoph Knosalla
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany
| | - Volkmar Falk
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany; Department of Cardiothoracic Surgery, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; ETH Zurich, Department of Health Sciences and Technology, Translational Cardiovascular Technology, LFW C 13.2, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Sajjad Soltani
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, Germany
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31
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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}
\usepackage{amsmath}
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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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32
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Laurence DW, Homburg H, Yan F, Tang Q, Fung KM, Bohnstedt BN, Holzapfel GA, Lee CH. A pilot study on biaxial mechanical, collagen microstructural, and morphological characterizations of a resected human intracranial aneurysm tissue. Sci Rep 2021; 11:3525. [PMID: 33568740 PMCID: PMC7876029 DOI: 10.1038/s41598-021-82991-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 01/25/2021] [Indexed: 02/08/2023] Open
Abstract
Intracranial aneurysms (ICAs) are focal dilatations that imply a weakening of the brain artery. Incidental rupture of an ICA is increasingly responsible for significant mortality and morbidity in the American’s aging population. Previous studies have quantified the pressure-volume characteristics, uniaxial mechanical properties, and morphological features of human aneurysms. In this pilot study, for the first time, we comprehensively quantified the mechanical, collagen fiber microstructural, and morphological properties of one resected human posterior inferior cerebellar artery aneurysm. The tissue from the dome of a right posterior inferior cerebral aneurysm was first mechanically characterized using biaxial tension and stress relaxation tests. Then, the load-dependent collagen fiber architecture of the aneurysm tissue was quantified using an in-house polarized spatial frequency domain imaging system. Finally, optical coherence tomography and histological procedures were used to quantify the tissue’s microstructural morphology. Mechanically, the tissue was shown to exhibit hysteresis, a nonlinear stress-strain response, and material anisotropy. Moreover, the unloaded collagen fiber architecture of the tissue was predominantly aligned with the testing Y-direction and rotated towards the X-direction under increasing equibiaxial loading. Furthermore, our histological analysis showed a considerable damage to the morphological integrity of the tissue, including lack of elastin, intimal thickening, and calcium deposition. This new unified characterization framework can be extended to better understand the mechanics-microstructure interrelationship of aneurysm tissues at different time points of the formation or growth. Such specimen-specific information is anticipated to provide valuable insight that may improve our current understanding of aneurysm growth and rupture potential.
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Affiliation(s)
- Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, 865 Asp Ave., Felgar Hall 219C, Norman, 73019, USA
| | - Hannah Homburg
- Department of Neurosurgery, The University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA
| | - Feng Yan
- Biophotonic Imaging Laboratory, Stephenson School of Biomedical Engineering, The University of Oklahoma, Norman, 73019, USA
| | - Qinggong Tang
- Biophotonic Imaging Laboratory, Stephenson School of Biomedical Engineering, The University of Oklahoma, Norman, 73019, USA
| | - Kar-Ming Fung
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA.,Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA
| | - Bradley N Bohnstedt
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, 8010, Graz, Austria.,Department of Structural Engineering, Norwegian University of Science and Technology, 7491, Trondheim, Norway
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, 865 Asp Ave., Felgar Hall 219C, Norman, 73019, USA. .,Institute for Biomedical Engineering, Science and Technology, The University of Oklahoma, Norman, OK, 73019, USA.
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33
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Kawakami Y, Nonaka K, Fukase N, Amore AD, Murata Y, Quinn P, Luketich S, Takayama K, Patel KG, Matsumoto T, Cummins JH, Kurosaka M, Kuroda R, Wagner WR, Fu FH, Huard J. A Cell-free Biodegradable Synthetic Artificial Ligament for the Reconstruction of Anterior Cruciate Ligament in a Rat Model. Acta Biomater 2021; 121:275-287. [PMID: 33129986 DOI: 10.1016/j.actbio.2020.10.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 12/16/2022]
Abstract
Traditional Anterior Cruciate Ligament (ACL) reconstruction is commonly performed using an allograft or autograft and possesses limitations such as donor site morbidity, decreased range of motion, and potential infection. However, a biodegradable synthetic graft could greatly assist in the prevention of such restrictions after ACL reconstruction. In this study, artificial grafts were generated using "wet" and "dry" electrospinning processes with a biodegradable elastomer, poly (ester urethane) urea (PEUU), and were evaluated in vitro and in vivo in a rat model. Four groups were established: (1) Wet PEUU artificial ligament, (2) Dry PEUU artificial ligament, (3) Dry polycaprolactone artificial ligament (PCL), and (4) autologous flexor digitorum longus tendon graft. Eight weeks after surgery, the in vivo tensile strength of wet PEUU ligaments had significantly increased compared to the other synthetic ligaments. These results aligned with increased infiltration of host cells and decreased inflammation within the wet PEUU grafts. In contrast, very little cellular infiltration was observed in PCL and dry PEUU grafts. Micro-computed tomography analysis performed at 4 and 8 weeks postoperatively revealed significantly smaller bone tunnels in the tendon autograft and wet PEUU groups. The Wet PEUU grafts served as an adequate functioning material and allowed for the creation of tissues that closely resembled the ACL.
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Affiliation(s)
- Yohei Kawakami
- Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA 15213; Stem Cell Research Center, University of Pittsburgh, Pittsburgh, PA 15219; Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Kazuhiro Nonaka
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Naomasa Fukase
- Steadman Philippon Research Institute, Vail CO 81657; Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Antonio D' Amore
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Yoichi Murata
- Steadman Philippon Research Institute, Vail CO 81657
| | - Patrick Quinn
- Steadman Philippon Research Institute, Vail CO 81657
| | - Samuel Luketich
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Koji Takayama
- Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA 15213; Stem Cell Research Center, University of Pittsburgh, Pittsburgh, PA 15219; Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Kunj G Patel
- Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA 15213; Stem Cell Research Center, University of Pittsburgh, Pittsburgh, PA 15219
| | - Tomoyuki Matsumoto
- Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | | | - Masahiro Kurosaka
- Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - Ryosuke Kuroda
- Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan
| | - William R Wagner
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Freddie H Fu
- Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Johnny Huard
- Steadman Philippon Research Institute, Vail CO 81657.
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Roseen MA, Lee R, Post AD, Wancura M, Connell JP, Cosgriff-Hernandez E, Grande-Allen KJ. Poly(ethylene glycol)-Based Coatings for Bioprosthetic Valve Tissues: Toward Restoration of Physiological Behavior. ACS APPLIED BIO MATERIALS 2020; 3:8352-8360. [PMID: 35019607 DOI: 10.1021/acsabm.0c00550] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bioprosthetic valves (BPVs) have a limited lifespan in the body necessitating repeated surgeries to replace the failed implant. Early failure of these implants has been linked to various surface properties of the valve. Surface properties of BPVs are significantly different from physiological valves because of the fixation process used when processing the xenograft tissue. To improve the longevity of BPVs, efforts need to be taken to improve the surface properties and shield the implant from the bodily interactions that degrade it. Toward this goal, we evaluated the use of hydrogel coatings to attach to the BPV tissue and impart surface properties that are close to physiological. Hydrogels are well characterized for their biocompatibility and highly tunable surface characteristics. Using a previously published coating method, we deposited hydrogel coatings of poly(ethylene glycol)diacrylate (PEGDA) and poly(ethylene glycol)diacrylamide (PEGDAA) atop BPV samples. Coated samples were evaluated against the physiological tissue and uncoated glutaraldehyde-fixed tissue for deposition of hydrogel, surface adherence, mechanical properties, and fixation properties. Results showed both PEGDA- and PEGDAA-deposited coatings were nearly continuous across the valve leaflet surface. Further, the PEGDA- and PEGDAA-coated samples showed restoration of physiological levels of protein adhesion and mechanical stiffness. Interestingly, the coating process rather than the coating itself altered the material behavior yet did not alter the cross-linking from fixation. These results show that the PEG-based coatings for BPVs can successfully alter surface properties of BPVs and help promote physiological characteristics without interfering with the necessary fixation.
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Affiliation(s)
- Madeleine A Roseen
- Department of Bioengineering, Rice University, Houston 77005, Texas, United States
| | - Romi Lee
- Department of Bioengineering, Rice University, Houston 77005, Texas, United States
| | - Allison D Post
- Department of Biomedical Engineering, University of Texas at Austin, Austin 78712, Texas, United States
| | - Megan Wancura
- Department of Chemistry, University of Texas at Austin, Austin 78712, Texas, United States
| | - Jennifer P Connell
- Department of Bioengineering, Rice University, Houston 77005, Texas, United States
| | | | - K Jane Grande-Allen
- Department of Bioengineering, Rice University, Houston 77005, Texas, United States
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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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36
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Constable M, Northeast R, Lawless BM, Burton HE, Gramigna V, Goh KL, Buchan KG, Espino DM. Mechanical testing of glutaraldehyde cross-linked mitral valves. Part two: Elastic and viscoelastic properties of chordae tendineae. Proc Inst Mech Eng H 2020; 235:291-299. [PMID: 33243079 DOI: 10.1177/0954411920975938] [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] [Indexed: 11/15/2022]
Abstract
The aim of this study was to assess whether the mechanical properties of mitral valve chordae tendineae are sensitive to being cross-linked under load. A total 64 chordae were extracted from eight porcine hearts. Two chordae (posterior basal) from each heart were subjected to uniaxial ramp testing and six chordae (two strut, two anterior basal and two posterior basal) were subjected to dynamic mechanical analysis over frequencies between 0.5 and 10 Hz. Chordae were either cross-linked in tension or cross-linked in the absence of loading. Chordae cross-linked under load transitioned from high to low extension at a lower strain than cross-linked unloaded chordae (0.07 cf. 0.22), with greater pre-transitional (30.8 MPa cf. 5.78 MPa) and post-transitional (139 MPa cf. 74.1 MPa) moduli. The mean storage modulus of anterior strut chordae ranged from 48 to 54 MPa for cross-linked unloaded chordae, as compared to 53-61 MPa cross-linked loaded chordae. The mean loss modulus of anterior strut chordae ranged from 2.3 to 2.9 MPa for cross-linked unloaded chordae, as compared to 3.8-4.8 MPa cross-linked loaded chordae. The elastic and viscoelastic properties of chordae following glutaraldehyde cross-linking are dependent on the inclusion/exclusion of loading during the cross-linking process; with loading increasing the magnitude of the material properties measured.
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Affiliation(s)
- Matthew Constable
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Rhiannon Northeast
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Bernard M Lawless
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK.,Filament PD, Level 4 - Skypark 3, Skypark, Glasgow, UK
| | - Hanna E Burton
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Vera Gramigna
- University of Magna Graecia, Catanzaro, Italy.,IBFM, National Research Council, Germaneto, Catanzaro, Italy
| | - Kheng Lim Goh
- Department of Mechanical Engineering, University of Newcastle, Singapore
| | - Keith G Buchan
- Department of Cardio-thoracic Surgery, Aberdeen Royal Infirmary, Forresterhill, Aberdeen, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
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Northeast R, Constable M, Burton HE, Lawless BM, Gramigna V, Lim Goh K, Buchan KG, Espino DM. Mechanical testing of glutaraldehyde cross-linked mitral valves. Part one: In vitro mechanical behaviour. Proc Inst Mech Eng H 2020; 235:281-290. [PMID: 33231114 DOI: 10.1177/0954411920975894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The aim of this study was to perform an initial assessment, in vitro, of the feasibility of using a glutaraldehyde cross-linked porcine mitral valve to retain acute functionality, focusing on assessing mitral regurgitation. Six porcine hearts were tested using an in vitro simulator. Testing was repeated following cross-linking of mitral valves; where cross-linking was achieved by placing them in a glutaraldehyde solution. The simulator enabled systolic pressure on the ventricular side of the valve to be mimicked. Following testing, mitral valve leaflets underwent Scanning Electron Microscopy of the ventricular surface of both the anterior and posterior leaflets (1 cm2 samples). The peak pressure withstood by cross-linked valves was significantly lower than for untreated valves (108 mmHg cf. 128 mmHg for untreated valves; p < 0.05). The peak pressure was typically reached 0.5 s later than for the untreated valve. While both cross-linked and untreated valves exhibited endothelium denudation, the unfixed valve had less endothelial loss. Glutaraldehyde cross-linking of porcine mitral valves may be of potential value in assessing improved bioprosthetic mitral valve replacements. However, a more immobile valve exhibiting endothelial denudation (i.e. sclerosis) was a possible concerns identified following in vitro acute assessment.
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Affiliation(s)
- Rhiannon Northeast
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Matthew Constable
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Hanna E Burton
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Bernard M Lawless
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK.,Filament PD, Level 4 - Skypark 3, Skypark, Glasgow, UK
| | - Vera Gramigna
- University of Magna Graecia, Catanzaro, Italy.,IBFM, National Research Council, Germaneto, Catanzaro, Italy
| | - Kheng Lim Goh
- Department of Mechanical Engineering, University of Newcastle, Singapore
| | - Keith G Buchan
- Department of Cardio-thoracic Surgery, Aberdeen Royal Infirmary, Forresterhill, Aberdeen, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
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38
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A versatile biaxial testing platform for soft tissues. J Mech Behav Biomed Mater 2020; 114:104144. [PMID: 33153924 DOI: 10.1016/j.jmbbm.2020.104144] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 09/02/2020] [Accepted: 10/14/2020] [Indexed: 11/20/2022]
Abstract
Uniaxial testing remains the most common modality of mechanical analysis for biological and other soft materials; however, biaxial testing enables a more comprehensive understanding of these materials' mechanical behavior. In recent years, a number of commercially available biaxial testing systems designed for biological materials have been produced; however, there are common limitations that are often associated with using these systems. For example, the range of allowable sample geometries are relatively constrained, the clamping systems are relatively limited with respect to allowable configurations, the load and displacement ranges are relatively small, and the software and control elements offer relatively limited options. Due to these constraints, there are significant benefits associated with designing custom biaxial testing systems that meet the technical requirements for testing a broad range of materials. Herein we present a design for a biaxial testing system with capabilities that extend beyond those associated with typical commercially available systems. Our design is capable of performing uniaxial tests, traditional biaxial tests, and double lap shear (simple shear) tests, in either a displacement or load control mode. Testing protocols have been developed and proof-of-concept experiments have been performed on commercially available silicone membranes and rat abdominal skin samples.
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39
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Wang DD, Qian Z, Vukicevic M, Engelhardt S, Kheradvar A, Zhang C, Little SH, Verjans J, Comaniciu D, O'Neill WW, Vannan MA. 3D Printing, Computational Modeling, and Artificial Intelligence for Structural Heart Disease. JACC Cardiovasc Imaging 2020; 14:41-60. [PMID: 32861647 DOI: 10.1016/j.jcmg.2019.12.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 11/27/2019] [Accepted: 12/02/2019] [Indexed: 01/19/2023]
Abstract
Structural heart disease (SHD) is a new field within cardiovascular medicine. Traditional imaging modalities fall short in supporting the needs of SHD interventions, as they have been constructed around the concept of disease diagnosis. SHD interventions disrupt traditional concepts of imaging in requiring imaging to plan, simulate, and predict intraprocedural outcomes. In transcatheter SHD interventions, the absence of a gold-standard open cavity surgical field deprives physicians of the opportunity for tactile feedback and visual confirmation of cardiac anatomy. Hence, dependency on imaging in periprocedural guidance has led to evolution of a new generation of procedural skillsets, concept of a visual field, and technologies in the periprocedural planning period to accelerate preclinical device development, physician, and patient education. Adaptation of 3-dimensional (3D) printing in clinical care and procedural planning has demonstrated a reduction in early-operator learning curve for transcatheter interventions. Integration of computation modeling to 3D printing has accelerated research and development understanding of fluid mechanics within device testing. Application of 3D printing, computational modeling, and ultimately incorporation of artificial intelligence is changing the landscape of physician training and delivery of patient-centric care. Transcatheter structural heart interventions are requiring in-depth periprocedural understanding of cardiac pathophysiology and device interactions not afforded by traditional imaging metrics.
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Affiliation(s)
- Dee Dee Wang
- Center for Structural Heart Disease, Division of Cardiology, Henry Ford Health System, Detroit, Michigan, USA.
| | - Zhen Qian
- Hippocrates Research Lab, Tencent America, Palo Alto, California, USA
| | - Marija Vukicevic
- Department of Cardiology, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas, USA
| | - Sandy Engelhardt
- Artificial Intelligence in Cardiovascular Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Arash Kheradvar
- Department of Biomedical Engineering, Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, California, USA
| | - Chuck Zhang
- H. Milton Stewart School of Industrial & Systems Engineering and Georgia Tech Manufacturing Institute, Georgia Institute of Technology, Atlanta Georgia, USA
| | - Stephen H Little
- Department of Cardiology, Methodist DeBakey Heart Center, Houston Methodist Hospital, Houston, Texas, USA
| | - Johan Verjans
- Australian Institute for Machine Learning, University of Adelaide, Adelaide South Australia, Australia
| | - Dorin Comaniciu
- Siemens Healthineers, Medical Imaging Technologies, Princeton, New Jersey, USA
| | - William W O'Neill
- Center for Structural Heart Disease, Division of Cardiology, Henry Ford Health System, Detroit, Michigan, USA
| | - Mani A Vannan
- Hippocrates Research Lab, Tencent America, Palo Alto, California, USA
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40
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Kuznetsov S, Pankow M, Peters K, Huang HYS. A structural-based computational model of tendon-bone insertion tissues. Math Biosci 2020; 327:108411. [PMID: 32623027 DOI: 10.1016/j.mbs.2020.108411] [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: 10/31/2019] [Revised: 06/28/2020] [Accepted: 06/28/2020] [Indexed: 10/23/2022]
Abstract
Tendon-to-bone insertion provides a gradual transition from soft tendon to hard bone tissue, functioning to alleviate stress concentrations at the junction of these tissues. Such macroscopic mechanical properties are achieved due to the internal structure in which collagen fibers and mineralization levels are key ingredients. We develop a structural-based model of tendon-to-bone insertion incorporating such details as fiber preferred orientation, fiber directional dispersion, mineralization level, and their inhomogeneous spatial distribution. A python script is developed to alter the tapered tendon-bone transition zone and to provide spatial grading of material properties, which may be rather complex as experiments suggest. A simple linear interpolation between tendon and bone material properties is first used to describe the graded property within the insertion region. Stress distributions are obtained and compared for spatially graded and various piece-wise materials properties. It is observed that spatial grading results in more smooth stress distributions and significantly reduces maximum stresses. The geometry of the tissue model is optimized by minimizing the peak stress to mimic in-vivo tissue remodeling. The in-silico elastic models constructed in this work are verified and modified by comparing to our in-situ biaxial mechanical testing results, thereby serving as translational tools for accurately predicting the material behavior of the tendon-to-bone insertions. This model will be useful for understanding how tendon-to-bone insertion develops during tissue remodeling, as well as for developing orthopedic implants.
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Affiliation(s)
| | - Mark Pankow
- North Carolina State University, United States of America
| | - Kara Peters
- North Carolina State University, United States of America
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41
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Witte M, Jaspers S, Wenck H, Rübhausen M, Fischer F. General method for classification of fiber families in fiber-reinforced materials: application to in-vivo human skin images. Sci Rep 2020; 10:10888. [PMID: 32616723 PMCID: PMC7331592 DOI: 10.1038/s41598-020-67632-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 06/04/2020] [Indexed: 11/17/2022] Open
Abstract
Fiber structures play a major role for the function of fiber-reinforced materials such as biological tissue. An objective classification of the fiber orientations into fiber families is crucial to understand its mechanical properties. We introduce the Fiber Image Network Evaluation Algorithm (FINE algorithm) to classify and quantify the number of fiber families in scientific images. Each fiber family is characterized by an amplitude, a mean orientation, and a dispersion. A new alignment index giving the averaged fraction of aligned fibers is defined. The FINE algorithm is validated by realistic grayscale Monte-Carlo fiber images. We apply the algorithm to an in-vivo depth scan of second harmonic generation images of dermal collagen in human skin. The derived alignment index exhibits a crossover at a critical depth where two fiber families with a perpendicular orientation around the main tension line arise. This strongly suggests the presence of a transition from the papillary to the reticular dermis. Hence, the FINE algorithm provides a valuable tool for a reliable classification and a meaningful interpretation of in-vivo collagen fiber networks and general fiber reinforced materials.
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Affiliation(s)
- Maximilian Witte
- Center for Free-Electron Laser Science (CFEL), University of Hamburg, 22607, Hamburg, Germany
- Beiersdorf AG, 20245, Hamburg, Germany
| | | | | | - Michael Rübhausen
- Center for Free-Electron Laser Science (CFEL), University of Hamburg, 22607, Hamburg, Germany
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42
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Qin T, Caballero A, Mao W, Barrett B, Kamioka N, Lerakis S, Sun W. The role of stress concentration in calcified bicuspid aortic valve. J R Soc Interface 2020; 17:20190893. [PMID: 32517630 DOI: 10.1098/rsif.2019.0893] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Calcific aortic valve disease (CAVD) is the most common valvular heart disease in the aging population, and is now believed to be a slow, progressive, yet actively regulated process. The disease progression can be divided into two phases: initiation phase associated with lipid deposition and inflammation response, and the later propagation phase with active calcification growth. It has been hypothesized that elevated mechanical stress plays a major role in both phases of disease progression. In order to identify a direct link between leaflet stress and calcification development, we performed patient-specific finite-element (FE) analyses of six bicuspid aortic valves (BAV), where the leaflets, raphe and calcifications were all considered. The results showed that during the initiation phase, calcium buildup is likely to occur along the leaflet-root attachment curve (ATC), and the commissures, which are subject to the most drastic changes in stress during the cardiac cycle. During the propagation phase, the presence of calcification would lead to local stress concentration along its boundary, hence further calcification growth. Three patterns of calcification formation were identified on BAV leaflets: 'radial', which extended radially from ATC into the leaflet belly region; 'commissure to commissure', which extended circumferentially along the coaptation; and 'raphe', which located in the vicinity of the raphe. Furthermore, we found a strong correlation between regions with a high risk of calcium buildup and regions with elevated mechanical stress. The high-risk regions predicted at diastole on the non-calcified leaflet from FE models agreed reasonably well with the in vivo calcification locations, which indicates that patient-specific FE modelling could help us to evaluate the potential risk of calcification formation in the early stage of CAVD.
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Affiliation(s)
- Tongran Qin
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Andrés Caballero
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Wenbin Mao
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Brian Barrett
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | | | - Stamatios Lerakis
- School of Medicine, Emory University, Atlanta, GA, USA.,Division of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Wei Sun
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
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43
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Lee JH, Rygg AD, Kolahdouz EM, Rossi S, Retta SM, Duraiswamy N, Scotten LN, Craven BA, Griffith BE. Fluid-Structure Interaction Models of Bioprosthetic Heart Valve Dynamics in an Experimental Pulse Duplicator. Ann Biomed Eng 2020; 48:1475-1490. [PMID: 32034607 PMCID: PMC7154025 DOI: 10.1007/s10439-020-02466-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 12/18/2019] [Indexed: 12/15/2022]
Abstract
Computer modeling and simulation is a powerful tool for assessing the performance of medical devices such as bioprosthetic heart valves (BHVs) that promises to accelerate device design and regulation. This study describes work to develop dynamic computer models of BHVs in the aortic test section of an experimental pulse-duplicator platform that is used in academia, industry, and regulatory agencies to assess BHV performance. These computational models are based on a hyperelastic finite element extension of the immersed boundary method for fluid-structure interaction (FSI). We focus on porcine tissue and bovine pericardial BHVs, which are commonly used in surgical valve replacement. We compare our numerical simulations to experimental data from two similar pulse duplicators, including a commercial ViVitro system and a custom platform related to the ViVitro pulse duplicator. Excellent agreement is demonstrated between the computational and experimental results for bulk flow rates, pressures, valve open areas, and the timing of valve opening and closure in conditions commonly used to assess BHV performance. In addition, reasonable agreement is demonstrated for quantitative measures of leaflet kinematics under these same conditions. This work represents a step towards the experimental validation of this FSI modeling platform for evaluating BHVs.
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Affiliation(s)
- Jae H Lee
- Department of Mathematics, University of North Carolina, Chapel Hill, NC, USA
| | - Alex D Rygg
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Ebrahim M Kolahdouz
- Department of Mathematics, University of North Carolina, Chapel Hill, NC, USA
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Simone Rossi
- Department of Mathematics, University of North Carolina, Chapel Hill, NC, USA
| | - Stephen M Retta
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Nandini Duraiswamy
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | | | - Brent A Craven
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Boyce E Griffith
- Departments of Mathematics, Applied Physical Sciences, and Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA.
- Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina, Chapel Hill, NC, USA.
- Computational Medicine Program, University of North Carolina, Chapel Hill, NC, USA.
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC, USA.
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44
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Yu H, Del Nido PJ, Geva T, Yang C, Wu Z, Rathod RH, Huang X, Billiar KL, Tang D. Multi-Band Surgery for Repaired Tetralogy of Fallot Patients With Reduced Right Ventricle Ejection Fraction: A Pilot Study. Front Physiol 2020; 11:198. [PMID: 32265727 PMCID: PMC7103653 DOI: 10.3389/fphys.2020.00198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 02/20/2020] [Indexed: 12/24/2022] Open
Abstract
Introduction Right ventricle (RV) failure is one of the most common symptoms among patients with repaired tetralogy of Fallot (TOF). The current surgery treatment approach including pulmonary valve replacement (PVR) showed mixed post-surgery outcomes. A novel PVR surgical strategy using active contracting bands is proposed to improve the post-PVR outcome. In lieu of testing the risky surgical procedures on real patients, computational simulations (virtual surgery) using biomechanical ventricle models based on patient-specific cardiac magnetic resonance (CMR) data were performed to test the feasibility of the PVR procedures with active contracting bands. Different band combination and insertion options were tested to identify optimal surgery designs. Method Cardiac magnetic resonance data were obtained from one TOF patient (male, age 23) whose informed consent was obtained. A total of 21 finite element models were constructed and solved following our established procedures to investigate the outcomes of the band insertion surgery. The non-linear anisotropic Mooney–Rivlin model was used as the material model. Five different band insertion plans were simulated (three single band models with different band locations, one model with two bands, and one model with three bands). Three band contraction ratios (10, 15, and 20%) and passive bands (0% contraction ratio) were tested. RV ejection fraction was used as the measure for cardiac function. Results The RV ejection fraction from the three-band model with 20% contraction increased to 41.58% from the baseline of 37.38%, a 4.20% absolute improvement. The RV ejection fractions from the other four band models with 20% contraction rate were 39.70, 39.45, and 40.70% (two-band) and 39.17%, respectively. The mean RV stress and strain values from all of the 21 models showed only modest differences (5–11%). Conclusion This pilot study demonstrated that the three-band model with 20% band contraction ratio led to 4.20% absolute improvement in the RV ejection fraction, which is considered as clinically significant. The passive elastic bands led to the reduction of the RV ejection fractions. The modeling results and surgical strategy need to be further developed and validated by a multi-patient study and animal experiments before clinical trial could become possible. Tissue regeneration techniques are needed to produce materials for the contracting bands.
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Affiliation(s)
- Han Yu
- School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Pedro J Del Nido
- Department of Cardiac Surgery, Boston Children's Hospital, Boston, MA, United States.,Department of Surgery, Harvard Medical School, Boston, MA, United States
| | - Tal Geva
- Department of Cardiology, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Chun Yang
- Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Zheyang Wu
- Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Rahul H Rathod
- Department of Cardiology, Boston Children's Hospital, Boston, MA, United States
| | - Xueying Huang
- School of Mathematical Sciences, Xiamen University, Xiamen, China
| | - Kristen L Billiar
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Dalin Tang
- School of Biological Science and Medical Engineering, Southeast University, Nanjing, China.,Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States
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45
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Blair MJ, Jones JD, Woessner AE, Quinn KP. Skin Structure-Function Relationships and the Wound Healing Response to Intrinsic Aging. Adv Wound Care (New Rochelle) 2020; 9:127-143. [PMID: 31993254 DOI: 10.1089/wound.2019.1021] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 08/09/2019] [Indexed: 02/06/2023] Open
Abstract
Significance: Chronic wounds, such as diabetic foot ulcers, venous stasis ulcers, and pressure ulcers affect millions of Americans each year, and disproportionately afflict our increasingly older population. Older individuals are predisposed to wound infection, repeated trauma, and the development of chronic wounds. However, a complete understanding of how the attributes of aging skin affect the wound healing process has remained elusive. Recent Advances: A variety of studies have demonstrated that the dermal matrix becomes thinner, increasingly crosslinked, and fragmented with advanced age. These structural changes, as well as an increase in cell senescence, result in altered collagen fiber remodeling and increased stiffness. Studies combining mechanical testing with advanced imaging techniques are providing new insights into the relationships between these age-related changes. Emerging research into the mechanobiology of aging and the wound healing process indicate that the altered mechanical environment of aged skin may have a significant effect on age-related delays in healing. Critical Issues: The interpretation and synthesis of clinical studies is confounded by the effects of common comorbidities that also contribute to the development of chronic wounds. A lack of quantitative biomarkers of wound healing and age-related changes makes understanding structure-function relationships during the wound healing process challenging. Future Directions: Additional work is needed to establish quantitative and mechanistic relationships among age-related changes in the skin microstructure, mechanical function, and the cellular responses to wound healing.
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Affiliation(s)
- Michael J. Blair
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Jake D. Jones
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Alan E. Woessner
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Kyle P. Quinn
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
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Heitkemper M, Hatoum H, Azimian A, Yeats B, Dollery J, Whitson B, Rushing G, Crestanello J, Lilly SM, Dasi LP. Modeling risk of coronary obstruction during transcatheter aortic valve replacement. J Thorac Cardiovasc Surg 2020; 159:829-838.e3. [PMID: 31230808 PMCID: PMC6859205 DOI: 10.1016/j.jtcvs.2019.04.091] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/06/2019] [Accepted: 04/16/2019] [Indexed: 01/06/2023]
Abstract
OBJECTIVE In this study we aimed to evaluate risk of coronary obstruction during transcatheter aortic valve replacement and develop improved criteria based on computational modeling. METHODS Patient specific 3-dimensional models were constructed and validated for 28 patients out of 600 patients who were flagged as high risk for coronary obstruction (defined as meeting coronary ostium height < 14 mm and/or sinus of Valsalva diameter [SOVd] < 30 mm). The models consisted finite element analysis to predict the post- transcatheter aortic valve replacement native cusp apposition relative to the coronary ostium and were validated in vitro. The distance from cusp to coronary ostium (DLC) was derived from the 3-dimensional models and indexed with the coronary artery diameter to yield a fractional obstruction measure (DLC/d). RESULTS Twenty-two out of 28 high-risk patients successfully underwent transcatheter aortic valve replacement without coronary obstruction and 6 did not. DLC/d between the 2 groups was significantly different (P < .00078), whereas neither coronary ostium height nor SOVd were significantly different (P > .32). A cutoff of DLC/d < 0.7 was predictive with 100% sensitivity and 95.7% specificity. The optimal sensitivity and specificity of coronary ostium height and SOVd in this high-risk group was only 60% and 40%, respectively, for cutoff coronary ostium height of 10 mm and SOVd of 30.5 mm. CONCLUSIONS Three-dimensional modeling has the potential to enable more patients to be safely treated with transcatheter aortic valve replacement who have a low-lying coronary ostium or small SOVd. DLC/d is more predictive of obstruction than coronary ostium height and SOVd.
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Affiliation(s)
- Megan Heitkemper
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Amirsepehr Azimian
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Breandan Yeats
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | | | - Bryan Whitson
- Department of Surgery The Ohio State University, Columbus, Ohio
| | - Greg Rushing
- Department of Surgery The Ohio State University, Columbus, Ohio
| | - Juan Crestanello
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio; Department of Surgery The Ohio State University, Columbus, Ohio
| | - Scott M Lilly
- Division of Cardiology, The Ohio State University, Columbus, Ohio
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio; Department of Surgery The Ohio State University, Columbus, Ohio.
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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: 22] [Impact Index Per Article: 4.4] [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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Noble C, Maxson EL, Lerman A, Young MD. Mechanical and finite element evaluation of a bioprinted scaffold following recellularization in a rat subcutaneous model. J Mech Behav Biomed Mater 2019; 102:103519. [PMID: 31879268 DOI: 10.1016/j.jmbbm.2019.103519] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 10/01/2019] [Accepted: 11/01/2019] [Indexed: 12/23/2022]
Abstract
Tissue engineered heart valves (TEHV) provide several advantages over currently available aortic heart valve replacements. Bioprinting provides a patient-specific means of developing a TEHV scaffold from imaging data, and the capability to embed the patient's own cells within the scaffold. In this work we investigated the remodeling capacity of a collagen-based bio-ink by implanting bioprinted disks in a rat subcutaneous model for 2, 4 and 12 weeks and evaluating the mechanical response using biaxial testing and subsequent finite element (FE) modeling. Samples explanted after 2 and 4 weeks showed inferior mechanical properties compared to native tissues while 12 week explants showed a mechanical response of similar magnitude but did not demonstrate the anisotropy present in native tissues. In the FE analysis, the model utilizing mechanical properties from samples explanted after 12 weeks showed the closest mechanical behavior to the native tissues. However, in diastole native tissues showed higher stress in the leaflet belly and lower strain at the commissures compared to 12 week explants, likely due to the anisotropy present in the native tissues. Thus, either further remodeling is required in situ in the aortic valve position or by in vitro preconditioning in an environment such as a bioreactor. Regardless, these results demonstrate the utility of FE analysis to optimize bioprinting process parameters for the most favorable in vivo mechanical performance.
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Affiliation(s)
- Christopher Noble
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Eva L Maxson
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Amir Lerman
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Melissa D Young
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
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Xue Y, Ravishankar P, Zeballos MA, Sant V, Balachandran K, Sant S. Valve leaflet‐inspired elastomeric scaffolds with tunable and anisotropic mechanical properties. POLYM ADVAN TECHNOL 2019. [DOI: 10.1002/pat.4750] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Yingfei Xue
- Department of Pharmaceutical SciencesUniversity of Pittsburgh Pittsburgh PA USA
| | | | | | - Vinayak Sant
- Department of Pharmaceutical SciencesUniversity of Pittsburgh Pittsburgh PA USA
| | - Kartik Balachandran
- Department of Biomedical EngineeringUniversity of Arkansas Fayetteville AR USA
| | - Shilpa Sant
- Department of Pharmaceutical SciencesUniversity of Pittsburgh Pittsburgh PA USA
- Department of BioengineeringUniversity of Pittsburgh Pittsburgh PA USA
- McGowan Institute for Regenerative MedicineUniversity of Pittsburgh Pittsburgh PA USA
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50
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Khoiy KA, Pant AD, Amini R. Quantification of Material Constants for a Phenomenological Constitutive Model of Porcine Tricuspid Valve Leaflets for Simulation Applications. J Biomech Eng 2019; 140:2681002. [PMID: 29801174 DOI: 10.1115/1.4040126] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Indexed: 11/08/2022]
Abstract
The tricuspid valve is a one-way valve on the pulmonary side of the heart, which prevents backflow of blood during ventricular contractions. Development of computational models of the tricuspid valve is important both in understanding the normal valvular function and in the development/improvement of surgical procedures and medical devices. A key step in the development of such models is quantification of the mechanical properties of the tricuspid valve leaflets. In this study, after examining previously measured five-loading-protocol biaxial stress-strain response of porcine tricuspid valves, a phenomenological constitutive framework was chosen to represent this response. The material constants were quantified for all three leaflets, which were shown to be highly anisotropic with average anisotropy indices of less than 0.5 (an anisotropy index value of 1 indicates a perfectly isotropic response, whereas a smaller value of the anisotropy index indicates an anisotropic response). To obtain mean values of material constants, stress-strain responses of the leaflet samples were averaged and then fitted to the constitutive model (average R2 over 0.9). Since the sample thicknesses were not hugely different, averaging the data using the same tension levels and stress levels produced similar average material constants for each leaflet.
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Affiliation(s)
- Keyvan Amini Khoiy
- Department of Biomedical Engineering, The University of Akron Olson Research Center, Room 322/3 260 South Forge Street, Akron, OH 44325 e-mail:
| | - Anup D Pant
- Department of Biomedical Engineering, The University of Akron Olson Research Center, Room 322/3 260 South Forge Street, Akron, OH 44325 e-mail:
| | - Rouzbeh Amini
- Mem. ASME Department of Biomedical Engineering, The University of Akron Olson Research Center, , Akron, OH 44325 e-mail:
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