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Quinaz T, Freire TF, Olmos A, Martins M, Ferreira FBN, de Moura MFSM, Zille A, Nguyễn Q, Xavier J, Dourado N. The Influence of Hydroxyapatite Crystals on the Viscoelastic Behavior of Poly(vinyl alcohol) Braid Systems. Biomimetics (Basel) 2024; 9:93. [PMID: 38392139 PMCID: PMC10886535 DOI: 10.3390/biomimetics9020093] [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] [Received: 12/28/2023] [Revised: 01/28/2024] [Accepted: 01/29/2024] [Indexed: 02/24/2024] Open
Abstract
Composites of poly(vinyl alcohol) (PVA) in the shape of braids, in combination with crystals of hydroxyapatite (HAp), were analyzed to perceive the influence of this bioceramic on both the quasi-static and viscoelastic behavior under tensile loading. Analyses involving energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) allowed us to conclude that the production of a homogeneous layer of HAp on the braiding surface and the calcium/phosphate atomic ratio were comparable to those of natural bone. The maximum degradation temperature established by thermogravimetric analysis (TGA) showed a modest decrease with the addition of HAp. By adding HAp to PVA braids, an increase in the glass transition temperature (Tg) is noticed, as demonstrated by dynamic mechanical analysis (DMA) and differential thermal analysis (DTA). The PVA/HAp composite braids' peaks were validated by Fourier transform infrared (FTIR) spectroscopy to be in good agreement with common PVA and HAp patterns. PVA/HAp braids, a solution often used in the textile industry, showed superior overall mechanical characteristics in monotonic tensile tests. Creep and relaxation testing showed that adding HAp to the eight and six-braided yarn architectures was beneficial. By exhibiting good mechanical performance and most likely increased biological qualities that accompany conventional care for bone applications in the fracture healing field, particularly multifragmentary ones, these arrangements can be applied as a fibrous fixation system.
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Affiliation(s)
- Tiago Quinaz
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
| | - Tânia F Freire
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
| | - Andrea Olmos
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
| | - Marcos Martins
- INESC TEC, R. Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Fernando B N Ferreira
- 2C2T-Centro de Ciência e Tecnologia Têxtil, Departamento de Engenharia Têxtil, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
| | - Marcelo F S M de Moura
- Departamento de Engenharia Mecânica, Faculdade de Engenharia da Universidade do Porto, 4200-464 Porto, Portugal
| | - Andrea Zille
- 2C2T-Centro de Ciência e Tecnologia Têxtil, Departamento de Engenharia Têxtil, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
| | - Quyền Nguyễn
- 2C2T-Centro de Ciência e Tecnologia Têxtil, Departamento de Engenharia Têxtil, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
| | - José Xavier
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- LASI, Intelligent Systems Associate Laboratory, 4800-058 Guimarães, Portugal
| | - Nuno Dourado
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Campus de Azurém, Universidade do Minho, 4804-533 Guimarães, Portugal
- LABBELS-Laboratório Associado, 4710-057 Braga, Portugal
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2
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Friis SJ, Hansen TS, Poulsen M, Gregersen H, Brüel A, Vinge Nygaard J. Biomechanical properties of the stomach: A comprehensive comparative analysis of human and porcine gastric tissue. J Mech Behav Biomed Mater 2023; 138:105614. [PMID: 36527978 DOI: 10.1016/j.jmbbm.2022.105614] [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: 09/05/2022] [Revised: 11/23/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
BACKGROUND Stomach-related disorders impose medical challenges and are associated with significant social and economic costs. The field of biomechanics is promising for understanding tissue behavior and for development of medical treatments and surgical interventions. In gastroenterology, animal models are often used when studies on humans are not possible. Often large animal models with similar anatomical characteristics (size and shape) are preferred. However, it is uncertain if stomachs from humans and large animals have similar mechanical properties. The aim of the present study is to characterize and compare hyper- and viscoelastic properties of porcine and human gastric tissue using tension and radial compression tests. METHODS Hyperelastic and viscoelastic properties were quantified from quasi-static ramp tests and stress relaxation tests. Tension in two directions and radial compression experiments were done on intact stomach wall samples as well as on separated mucosa and muscularis layer samples from porcine and human fundus, corpus and antrum. RESULTS AND CONCLUSIONS Similar hyper- and viscoelastic constitutive models can be used to describe porcine and human gastric tissue. In total, 19 constitutive parameters were compared and results showed significant variations between species. For example, for intact circumferential samples from antrum, the stiffness (a) and relaxation (τ1) were greater for human samples than for porcine samples (p < 0.0001). The constitutive parameters were condition-, region- and layer-dependent and no distinct pattern hereof between species was found. This indicates that different parameters must be used to describe the specific situation. The present work provides insight into porcine and human gastric radial compressive and tensile hyper- and viscoelastic properties, strengthening the inter-species relation of the biomechanical properties. Constitutive relations were established that may aid development and translation of diagnostic or therapeutic devices with computational models.
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Affiliation(s)
- Sif Julie Friis
- Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark; Alternative Delivery Technologies, Device & Delivery Solutions, Novo Nordisk A/S, Hilleroed, Denmark
| | | | - Mette Poulsen
- Alternative Delivery Technologies, Device & Delivery Solutions, Novo Nordisk A/S, Hilleroed, Denmark
| | - Hans Gregersen
- California Medical Innovations Institute, San Diego, CA, USA
| | - Annemarie Brüel
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Jens Vinge Nygaard
- Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.
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3
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Sif Julie F, Torben Strøm H, Mette P, Hans G, Jens Vinge N. Dynamic viscoelastic properties of porcine gastric tissue: Effects of loading frequency, region and direction. J Biomech 2022; 143:111302. [PMID: 36126503 DOI: 10.1016/j.jbiomech.2022.111302] [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: 06/07/2022] [Revised: 08/18/2022] [Accepted: 09/09/2022] [Indexed: 12/30/2022]
Abstract
The gastric biomechanics influences digestive function as well as a range of topics of medical and scientific interests such as interaction between the stomach and gastric devices. Hence, the mechanical properties are essential for understanding gastric tissue and function in health and disease, and for the development of diagnostic or therapeutic devices. A key characteristic to be characterized is the time dependent mechanical tissue properties. The aim of this study was to characterize viscoelastic properties of the stomach across a frequency range. Longitudinal and circumferential stomach samples from the porcine fundus, corpus and antrum were pre-stretched 10 % and sinusoidally loaded with 10 % dynamic strain. The viscoelastic properties were assessed from 0.01 - 15 Hz using dynamic mechanical analysis. The storage moduli, loss moduli and tan δ had a significant second-order polynomial trend with increasing frequency. For the loss moduli, significant differences were observed between 0.01 and 15 Hz and between 0.05 and 15 Hz (p = 0.023 to 0.041). Significant differences were not found for storage moduli. Tan δ was frequency-independent, indicating that the two moduli varied proportionally. Fundus had significantly smaller storage moduli for longitudinal samples compared to corpus (p = 0.034) and antrum (p = 0.014) but was not significantly different for circumferential samples. Analysis of direction-dependency showed significant differences between longitudinal and circumferential samples (p = 0.002 to 0.042). The presented work provides insight into tensile viscoelastic properties of gastric tissue, which is useful for developing biomaterials, devices and computational models for device development specification calibrations.
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Affiliation(s)
- Friis Sif Julie
- Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark; Alternative Delivery Technologies, Device & Delivery Solutions, Novo Nordisk A/S, Hilleroed, Denmark
| | | | - Poulsen Mette
- Alternative Delivery Technologies, Device & Delivery Solutions, Novo Nordisk A/S, Hilleroed, Denmark
| | - Gregersen Hans
- California Medical Innovations Institute, San Diego, CA, United States
| | - Nygaard Jens Vinge
- Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.
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4
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Li W, Shepherd DET, Espino DM. Investigation of the Compressive Viscoelastic Properties of Brain Tissue Under Time and Frequency Dependent Loading Conditions. Ann Biomed Eng 2021; 49:3737-3747. [PMID: 34608583 PMCID: PMC8671270 DOI: 10.1007/s10439-021-02866-0] [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: 08/16/2021] [Accepted: 09/09/2021] [Indexed: 10/25/2022]
Abstract
The mechanical characterization of brain tissue has been generally analyzed in the frequency and time domain. It is crucial to understand the mechanics of the brain under realistic, dynamic conditions and convert it to enable mathematical modelling in a time domain. In this study, the compressive viscoelastic properties of brain tissue were investigated under time and frequency domains with the same physical conditions and the theory of viscoelasticity was applied to estimate the prediction of viscoelastic response in the time domain based on frequency-dependent mechanical moduli through Finite Element models. Storage and loss modulus were obtained from white and grey matter, of bovine brains, using dynamic mechanical analysis and time domain material functions were derived based on a Prony series representation. The material models were evaluated using brain testing data from stress relaxation and hysteresis in the time dependent analysis. The Finite Element models were able to represent the trend of viscoelastic characterization of brain tissue under both testing domains. The outcomes of this study contribute to a better understanding of brain tissue mechanical behaviour and demonstrate the feasibility of deriving time-domain viscoelastic parameters from frequency-dependent compressive data for biological tissue, as validated by comparing experimental tests with computational simulations.
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Affiliation(s)
- Weiqi Li
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Duncan E T Shepherd
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
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5
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Siami M, Jahani K, Rezaee M. Identifying the parameters of viscoelastic model for a gel-type material as representative of cardiac muscle in dynamic tests. Proc Inst Mech Eng H 2021; 235:1205-1216. [PMID: 34137313 DOI: 10.1177/09544119211025868] [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] [Indexed: 11/15/2022]
Abstract
In this paper, mechanical parameters of a calf heart muscle are identified and a gel-type material as the representative of the cardiac muscle in dynamic tests is introduced. The motivation of this study is to introduce a replacement material of the heart muscle to use in experimental studies of the leadless pacemaker. A particular test setup is developed to capture the experimental data based on the stress relaxation test method where its outputs are time histories of the force and displacement. The standard linear solid model is used for mathematical modeling of the heart muscle sample and a gel-type material specimen namely α-gel. Five tests with different strain history (13.6%,17.1%,20.6%22.4%and,23.8%) are performed by regarding and disregarding the influence of the initial ramp of the loading. The mechanical parameters of the standard linear solid model were identified with precise curve fitting. Consideration of the initial ramp significantly influences the consequences and they are so close to their experimental counterparts. The identified parameters of the standard linear solid model by regarding the influence of the initial ramp for the gel-type material are within an acceptable range for the viscoelastic properties of the calf heart tissue. These results show that the gel-type material has the potential to represent the cardiac muscle in the leadless pacemaker experimental studies. Dynamic mechanical analysis is used to characterize the dynamic viscoelastic properties for the gel by utilizing the identified parameters with taking into account the initial ramp in the frequency domain. Results show that Storage modulus, Loss modulus, and Loss tangent are strongly frequency-dependent especially at low-frequency around the heartbeat frequency range (0-2 Hz).
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Affiliation(s)
- Majid Siami
- Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran
| | - Kamal Jahani
- Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran
| | - Mousa Rezaee
- Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran
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6
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The effect of injurious compression on the elastic, hyper-elastic and visco-elastic properties of porcine peripheral nerves. J Mech Behav Biomed Mater 2021; 121:104624. [PMID: 34139483 DOI: 10.1016/j.jmbbm.2021.104624] [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: 04/09/2020] [Revised: 11/06/2020] [Accepted: 05/31/2021] [Indexed: 11/20/2022]
Abstract
The aim of this study was to characterise the viscoelastic and hyper-elastic properties of the ulnar nerve before and after compression has been induced, in order to aid the understanding of how the mechanical properties of nerves are altered during nerve compression, a contributing factor to cubital tunnel syndrome. Ulnar nerves were dissected from porcine legs and tensile tested to 10% strain. The Young's modulus and Yeoh hyper-elastic model were used to evaluate the materials elastic and hyper-elastic properties respectively. Dynamic mechanical analysis (DMA) was used to evaluate the viscoelastic properties over a range of frequencies between 0.5 Hz and 38 Hz. The nerves were then compressed to 40% for 60 s and the same tests were carried out after compression. The nerves were stiffer after compression, the mean Young's modulus before was 0.181 MPa and increased to 0.601 MPa after compression. The mean shear modulus calculated from the Yeoh hyper-elastic model was also higher after compression increasing from 5 kPa to 7 kPa. After compression, these properties had significantly increased (p < 0.05). The DMA results showed that the nerves exhibit frequency dependent viscoelastic behaviour across all tested frequencies. The median values of storage modulus before compression ranged between 0.605 and 0.757 MPa across the frequencies and after compression between 1.161 MPa and 1.381 MPa. There was a larger range of median values for loss modulus, before compression, median values ranged between 0.073 MPa and 0.216 MPa and after compression from 0.165 MPa to 0.410 MPa. There was a significant increase in both storage and loss modulus after compression (p < 0.05). The mechanical properties of the nerve change following compression, however the response to decompression in vivo requires further evaluation to determine whether the observed changes persist, which may have implications for clinical recovery after surgical decompression in entrapment neuropathy.
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7
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Dry vs. wet: Properties and performance of collagen films. Part II. Cyclic and time-dependent behaviours. J Mech Behav Biomed Mater 2020; 112:104040. [DOI: 10.1016/j.jmbbm.2020.104040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/08/2020] [Accepted: 08/12/2020] [Indexed: 12/21/2022]
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8
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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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9
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Taylor S, Buchan KG, Espino DM. The role of strut chordae in mitral valve competence during annular dilation. Perfusion 2020; 36:253-260. [PMID: 32693675 PMCID: PMC8041452 DOI: 10.1177/0267659120941340] [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] [Indexed: 12/11/2022]
Abstract
Strut chordae, on their own, are not typically thought to aid mitral valve competence. The aim of this study is to assess whether strut chordae aid mitral valve competence during acute annular dilation. Twelve porcine hearts were dissected and tested using an in vitro simulator, with the mitral annulus tested in either a 'normal' or a dilated configuration. The normal configuration included a diameter of 30 mm, a posterior leaflet 'radius' of 15 mm and a commissural corner 'radius' of 7.5 mm; the dilated annular template instead used dimensions of 50 mm, 25 mm and 12.5 mm, respectively. Each mitral valve underwent ten repeat tests with a target systolic pressure of 100 mmHg. No significant difference in the pressure was detected between the dilated and regular annuli for the mitral valves tested (95 ± 3 mmHg cf. 95 ± 2 mmHg). However, the volume of regurgitation for a dilated annulus was 28 ml greater than for a valve with a normal annulus. Following severing of strut chordae, there was a significant reduction in the systolic pressure withstood before regurgitation by mitral valves with dilated annuli (60 ± 29 mmHg cf. 95 ± 2 mmHg for normal annular dimensions; p < 0.05). In conclusion, strut chordae tendineae may play a role in aiding mitral valve competence during pathophysiology.
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Affiliation(s)
- Samuel Taylor
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Keith G Buchan
- Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary, Aberdeen, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
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10
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Taylor S, Buchan KG, Espino DM. The role of strut chordae in mitral valve competence during annular dilation. Perfusion 2020. [PMID: 32693675 DOI: 10.1177/0267659120941340.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Strut chordae, on their own, are not typically thought to aid mitral valve competence. The aim of this study is to assess whether strut chordae aid mitral valve competence during acute annular dilation. Twelve porcine hearts were dissected and tested using an in vitro simulator, with the mitral annulus tested in either a 'normal' or a dilated configuration. The normal configuration included a diameter of 30 mm, a posterior leaflet 'radius' of 15 mm and a commissural corner 'radius' of 7.5 mm; the dilated annular template instead used dimensions of 50 mm, 25 mm and 12.5 mm, respectively. Each mitral valve underwent ten repeat tests with a target systolic pressure of 100 mmHg. No significant difference in the pressure was detected between the dilated and regular annuli for the mitral valves tested (95 ± 3 mmHg cf. 95 ± 2 mmHg). However, the volume of regurgitation for a dilated annulus was 28 ml greater than for a valve with a normal annulus. Following severing of strut chordae, there was a significant reduction in the systolic pressure withstood before regurgitation by mitral valves with dilated annuli (60 ± 29 mmHg cf. 95 ± 2 mmHg for normal annular dimensions; p < 0.05). In conclusion, strut chordae tendineae may play a role in aiding mitral valve competence during pathophysiology.
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Affiliation(s)
- Samuel Taylor
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Keith G Buchan
- Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary, Aberdeen, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
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11
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Oliveira D, Srinivasan J, Espino D, Buchan K, Dawson D, Shepherd D. Geometric description for the anatomy of the mitral valve: A review. J Anat 2020; 237:209-224. [PMID: 32242929 DOI: 10.1111/joa.13196] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 12/16/2022] Open
Abstract
The mitral valve is a complex anatomical structure whose physiological functioning relies on the biomechanical properties and structural integrity of its components. Their compromise can lead to mitral valve dysfunction, associated with morbidity and mortality. Therefore, a review on the morphometry of the mitral valve is crucial, more specifically on the importance of valve dimensions and shape for its function. This review initially provides a brief background on the anatomy and physiology of the mitral valve, followed by an analysis of the morphological information available. A characterisation of mathematical descriptions of several parts of the valve is performed and the impact of different dimensions and shape changes in disease is then outlined. Finally, a section regarding future directions and recommendations for the use of morphometric information in clinical analysis of the mitral valve is presented.
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Affiliation(s)
- Diana Oliveira
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | | | - Daniel Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Keith Buchan
- Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary, Aberdeen, UK
| | - Dana Dawson
- Cardiology Research Facility, University of Aberdeen and Aberdeen Royal Infirmary, Aberdeen, UK
| | - Duncan Shepherd
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
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12
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Quantifying tactile properties of liver tissue, silicone elastomers, and a 3D printed polymer for manufacturing realistic organ models. J Mech Behav Biomed Mater 2020; 104:103630. [DOI: 10.1016/j.jmbbm.2020.103630] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 01/17/2023]
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13
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Frequency dependent viscoelastic properties of porcine brain tissue. J Mech Behav Biomed Mater 2020; 102:103460. [DOI: 10.1016/j.jmbbm.2019.103460] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/24/2019] [Accepted: 09/28/2019] [Indexed: 02/06/2023]
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14
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Lee CH, Laurence DW, Ross CJ, Kramer KE, Babu AR, Johnson EL, Hsu MC, Aggarwal A, Mir A, Burkhart HM, Towner RA, Baumwart R, Wu Y. Mechanics of the Tricuspid Valve-From Clinical Diagnosis/Treatment, In-Vivo and In-Vitro Investigations, to Patient-Specific Biomechanical Modeling. Bioengineering (Basel) 2019; 6:E47. [PMID: 31121881 PMCID: PMC6630695 DOI: 10.3390/bioengineering6020047] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 12/29/2022] Open
Abstract
Proper tricuspid valve (TV) function is essential to unidirectional blood flow through the right side of the heart. Alterations to the tricuspid valvular components, such as the TV annulus, may lead to functional tricuspid regurgitation (FTR), where the valve is unable to prevent undesired backflow of blood from the right ventricle into the right atrium during systole. Various treatment options are currently available for FTR; however, research for the tricuspid heart valve, functional tricuspid regurgitation, and the relevant treatment methodologies are limited due to the pervasive expectation among cardiac surgeons and cardiologists that FTR will naturally regress after repair of left-sided heart valve lesions. Recent studies have focused on (i) understanding the function of the TV and the initiation or progression of FTR using both in-vivo and in-vitro methods, (ii) quantifying the biomechanical properties of the tricuspid valve apparatus as well as its surrounding heart tissue, and (iii) performing computational modeling of the TV to provide new insight into its biomechanical and physiological function. This review paper focuses on these advances and summarizes recent research relevant to the TV within the scope of FTR. Moreover, this review also provides future perspectives and extensions critical to enhancing the current understanding of the functioning and remodeling tricuspid valve in both the healthy and pathophysiological states.
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Affiliation(s)
- Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
- Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, OK 73019, USA.
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Colton J Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Katherine E Kramer
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Anju R Babu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha 769008, India.
| | - Emily L Johnson
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ankush Aggarwal
- Glasgow Computational Engineering Centre, School of Engineering, University of Glasgow, Scotland G12 8LT, UK.
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Rheal A Towner
- Advance Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
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15
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The Effect of Mechanical Overloading on Surface Roughness of the Coronary Arteries. Appl Bionics Biomech 2019; 2019:2784172. [PMID: 30809272 PMCID: PMC6364105 DOI: 10.1155/2019/2784172] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/29/2018] [Accepted: 01/01/2019] [Indexed: 01/03/2023] Open
Abstract
Background Surface roughness can be used to identify disease within biological tissues. Quantifying surface roughness in the coronary arteries aids in developing treatments for coronary heart disease. This study investigates the effect of extreme physiological loading on surface roughness, for example, due to a rupture of an artery. Methods The porcine left anterior descending (LAD) coronary arteries were dissected ex vivo. Mechanical overloading was applied to the arteries in the longitudinal direction to simulate extreme physiological loading. Surface roughness was calculated from three-dimensional reconstructed images. Surface roughness was measured before and after damage and after chemical processing to dehydrate tissue specimens. Results Control specimens confirmed that dehydration alone results in an increase of surface roughness in the circumferential direction only. No variation was noted between the hydrated healthy and damaged specimens, in both the longitudinal (0.91 ± 0.26 and 1.05 ± 0.25 μm) and circumferential (1.46 ± 0.38 and 1.47 ± 0.39 μm) directions. After dehydration, an increase in surface roughness was noted for damaged specimens in both the longitudinal (1.28 ± 0.33 μm) and circumferential (1.95 ± 0.56 μm) directions. Conclusions Mechanical overloading applied in the longitudinal direction did not significantly affect surface roughness. However, when combined with chemical processing, a significant increase in surface roughness was noted in both the circumferential and longitudinal directions. Mechanical overloading causes damage to the internal constituents of the arteries, which is significantly noticeable after dehydration of tissue.
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16
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Towards viscoelastic characterisation of the human ulnar nerve: An early assessment using embalmed cadavers. Med Eng Phys 2019; 64:15-22. [DOI: 10.1016/j.medengphy.2018.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 11/22/2018] [Accepted: 12/04/2018] [Indexed: 11/18/2022]
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17
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Wu B, Zhao S, Shi H, Lu R, Yan B, Ma S, Markert B. Viscoelastic properties of human periodontal ligament: Effects of the loading frequency and location. Angle Orthod 2019; 89:480-487. [PMID: 30605020 DOI: 10.2319/062818-481.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES To determine the viscoelastic properties of the human periodontal ligament (PDL) using dynamic mechanical analysis (DMA). MATERIALS AND METHODS This study was carried out on three human maxillary jaw segments containing six upper central incisors and four lateral incisors. DMA was used to investigate the mechanical response of the human PDL. Dynamic sinusoidal loading was carried out with an amplitude of 3 N and frequencies between 0.5 Hz and 10 Hz. All samples were grouped by tooth positions and longitudinal locations. RESULTS An increase of oscillation frequency resulted in marked changes in the storage and loss moduli of the PDL. The storage modulus ranged from 0.808 MPa to 7.274 MPa, and the loss modulus varied from 0.087 MPa to 0.891 MPa. The tanδ, representing the ratio between viscosity and elasticity, remained constant with frequency. The trends for storage and loss moduli were described by exponential fits. The dynamic moduli of the central incisor were higher than those of the lateral incisor. The PDL samples from the gingival third of the root showed lower storage and loss moduli than those from the middle third of the root. CONCLUSIONS Human PDL is viscoelastic through the range of frequencies tested: 0.5-10 Hz. The viscoelastic relationship changed with respect to frequency, tooth position, and root level.
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18
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Park J, Geirsson A, Bonde PN. Mathematical Blueprint of a Mitral Valve. Semin Thorac Cardiovasc Surg 2019; 31:399-411. [DOI: 10.1053/j.semtcvs.2019.01.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/02/2019] [Indexed: 01/01/2023]
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19
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Freij JM, Burton HE, Espino DM. Objective Uniaxial Identification of Transition Points in Non-Linear Materials: Sample Application to Porcine Coronary Arteries and the Dependency of Their Pre- and Post-Transitional Moduli with Position. Cardiovasc Eng Technol 2018; 10:61-68. [DOI: 10.1007/s13239-018-00395-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 11/17/2018] [Indexed: 11/24/2022]
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20
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Early relaxation time assessment for characterization of breast tissue and diagnosis of breast tumors. J Mech Behav Biomed Mater 2018; 87:325-335. [DOI: 10.1016/j.jmbbm.2018.07.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 07/10/2018] [Accepted: 07/26/2018] [Indexed: 11/23/2022]
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21
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Constable M, Burton HE, Lawless BM, Gramigna V, Buchan KG, Espino DM. Effect of glutaraldehyde based cross-linking on the viscoelasticity of mitral valve basal chordae tendineae. Biomed Eng Online 2018; 17:93. [PMID: 30001710 PMCID: PMC6044032 DOI: 10.1186/s12938-018-0524-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/05/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mitral valve failure can require repair or replacement. Replacement bioprosthetic valves are treated with glutaraldehyde prior to implantation. The aim of this study was to determine the changes in mechanical properties following glutaraldehyde fixation of mitral valve chordae. METHODS To investigate the impact of glutaraldehyde on mitral valve chordae, 24 basal chordae were dissected from four porcine hearts. Anterior and posterior basal (including strut) chordae were used. All 24 chordae were subjected to a sinusoidally varying load (mean level 2N, dynamic amplitude 2N) over a frequency range of 0.5-10 Hz before and after glutaraldehyde treatment. RESULTS The storage and loss modulus of all chordal types decreased following glutaraldehyde fixation. The storage modulus ranged from: 108 to 119 MPa before fixation and 67.3-87.4 MPa following fixation for basal chordae; 52.3-58.4 MPa before fixation and 47.9-53.5 MPa following fixation for strut chordae. Similarly, the loss modulus ranged from: 5.47 to 6.25 MPa before fixation and 3.63-4.94 MPa following fixation for basal chordae; 2.60-2.97 MPa before fixation and 2.31-2.93 MPa following fixation for strut chordae. CONCLUSION The viscoelastic properties of mitral valve chordae are affected by glutaraldehyde fixation; in particular, the reduction in storage moduli decreased with an increase in chordal diameter.
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Affiliation(s)
- M Constable
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
| | - H E Burton
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK.,PDR, International Centre for Design and Research, Cardiff Metropolitan University, Cardiff, CF5 2YB, UK
| | - B M Lawless
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
| | - V Gramigna
- University of Magna Graecia, Catanzaro, Italy.,IBFM, National Research Council, Germaneto, Catanzaro, Italy
| | - K G Buchan
- Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary, Foresterhill, Aberdeen, AB25 2ZN, UK
| | - D M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
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22
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Jewkes R, Burton HE, Espino DM. Towards Additive Manufacture of Functional, Spline-Based Morphometric Models of Healthy and Diseased Coronary Arteries: In Vitro Proof-of-Concept Using a Porcine Template. J Funct Biomater 2018; 9:E15. [PMID: 29393899 PMCID: PMC5872101 DOI: 10.3390/jfb9010015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 01/26/2018] [Accepted: 01/31/2018] [Indexed: 12/21/2022] Open
Abstract
The aim of this study is to assess the additive manufacture of morphometric models of healthy and diseased coronary arteries. Using a dissected porcine coronary artery, a model was developed with the use of computer aided engineering, with splines used to design arteries in health and disease. The model was altered to demonstrate four cases of stenosis displaying varying severity, based on published morphometric data available. Both an Objet Eden 250 printer and a Solidscape 3Z Pro printer were used in this analysis. A wax printed model was set into a flexible thermoplastic and was valuable for experimental testing with helical flow patterns observed in healthy models, dominating the distal LAD (left anterior descending) and left circumflex arteries. Recirculation zones were detected in all models, but were visibly larger in the stenosed cases. Resin models provide useful analytical tools for understanding the spatial relationships of blood vessels, and could be applied to preoperative planning techniques, but were not suitable for physical testing. In conclusion, it is feasible to develop blood vessel models enabling experimental work; further, through additive manufacture of bio-compatible materials, there is the possibility of manufacturing customized replacement arteries.
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Affiliation(s)
- Rachel Jewkes
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, UK.
| | - Hanna E Burton
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, UK.
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, UK.
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23
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Gao H, Qi N, Feng L, Ma X, Danton M, Berry C, Luo X. Modelling mitral valvular dynamics-current trend and future directions. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e2858. [PMID: 27935265 PMCID: PMC5697636 DOI: 10.1002/cnm.2858] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 09/30/2016] [Accepted: 11/26/2016] [Indexed: 05/19/2023]
Abstract
Dysfunction of mitral valve causes morbidity and premature mortality and remains a leading medical problem worldwide. Computational modelling aims to understand the biomechanics of human mitral valve and could lead to the development of new treatment, prevention and diagnosis of mitral valve diseases. Compared with the aortic valve, the mitral valve has been much less studied owing to its highly complex structure and strong interaction with the blood flow and the ventricles. However, the interest in mitral valve modelling is growing, and the sophistication level is increasing with the advanced development of computational technology and imaging tools. This review summarises the state-of-the-art modelling of the mitral valve, including static and dynamics models, models with fluid-structure interaction, and models with the left ventricle interaction. Challenges and future directions are also discussed.
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Affiliation(s)
- Hao Gao
- School of Mathematics and StatisticsUniversity of GlasgowUK
| | - Nan Qi
- School of Mathematics and StatisticsUniversity of GlasgowUK
| | - Liuyang Feng
- School of Mathematics and StatisticsUniversity of GlasgowUK
| | | | - Mark Danton
- Department of Cardiac SurgeryRoyal Hospital for ChildrenGlasgowUK
| | - Colin Berry
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowUK
| | - Xiaoyu Luo
- School of Mathematics and StatisticsUniversity of GlasgowUK
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24
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Baxter J, Buchan KG, Espino DM. Viscoelastic properties of mitral valve leaflets: An analysis of regional variation and frequency-dependency. Proc Inst Mech Eng H 2017; 231:938-944. [PMID: 28707559 DOI: 10.1177/0954411917719741] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this study was to determine the regional variation in viscoelastic properties of mitral valve leaflets over a range of physiological and patho-physiological frequencies. This included comparisons to be made between anterior and posterior leaflets, anterior leaflet clear and rough zones, and radial and circumferential leaflet orientation. Dynamic mechanical analysis was used to determine frequency-dependent viscoelastic properties. The valve leaflets were dissected from eight porcine hearts. The leaflets were loaded under a sinusoidal tensile displacement, with a mean dynamic peak to trough strain of 11%, applied to all leaflet samples at nine different frequencies, ranging from 0.5 to 10 Hz. The anterior leaflet has higher storage and loss stiffness than the posterior leaflet. The storage stiffness of circumferential tissue is greater than that of radially oriented valve tissue (2.0 ± 1.6 N/mm cf. 1.7 ± 0.9 N/mm; p < 0.05); however, the loss stiffness is greater for radial tissue (0.15 ± 0.07 cf. 0.14 ± 0.09 N/mm; p < 0.05). Likewise, the storage stiffness of the anterior leaflet clear zone is greater than that of the rough zone (2.4 ± 1.6 cf. 2.1 ± 1.2; p < 0.05), but the loss stiffness is greater for the rough zone (0.17 ± 0.09 N/mm cf. 0.14 ± 0.08 N/mm; p < 0.05). In conclusion, the viscoelastic properties of porcine mitral valve leaflets have regional variations, with dynamic stiffness being dependent on circumferential or radial orientation and on location at a clear or rough zones.
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Affiliation(s)
- Jonathan Baxter
- 1 Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Keith G Buchan
- 2 Cardiothoracic Surgery, Aberdeen Royal Infirmary, Aberdeen, UK
| | - Daniel M Espino
- 1 Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
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25
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Burton HE, Freij JM, Espino DM. Dynamic Viscoelasticity and Surface Properties of Porcine Left Anterior Descending Coronary Arteries. Cardiovasc Eng Technol 2017; 8:41-56. [PMID: 27957718 PMCID: PMC5320017 DOI: 10.1007/s13239-016-0288-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 11/30/2016] [Indexed: 12/12/2022]
Abstract
The aim of this study was, for the first time, to measure and compare quantitatively the viscoelastic properties and surface roughness of coronary arteries. Porcine left anterior descending coronary arteries were dissected ex vivo. Viscoelastic properties were measured longitudinally using dynamic mechanical analysis, for a range of frequencies from 0.5 to 10 Hz. Surface roughness was calculated following three-dimensional reconstructed of surface images obtained using an optical microscope. Storage modulus ranged from 14.47 to 25.82 MPa, and was found to be frequency-dependent, decreasing as the frequency increased. Storage was greater than the loss modulus, with the latter found to be frequency-independent with a mean value of 2.10 ± 0.33 MPa. The circumferential surface roughness was significantly greater (p < 0.05) than the longitudinal surface roughness, ranging from 0.73 to 2.83 and 0.35 to 0.92 µm, respectively. However, if surface roughness values were corrected for shrinkage during processing, circumferential and longitudinal surface roughness were not significantly different (1.04 ± 0.47, 0.89 ± 0.27 µm, respectively; p > 0.05). No correlation was found between the viscoelastic properties and surface roughness. It is feasible to quantitatively measure the viscoelastic properties of coronary arteries and the roughness of their endothelial surface.
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Affiliation(s)
- Hanna E. Burton
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT UK
| | - Jenny M. Freij
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT UK
| | - Daniel M. Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT UK
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26
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Lawless BM, Barnes SC, Espino DM, Shepherd DET. Viscoelastic properties of a spinal posterior dynamic stabilisation device. J Mech Behav Biomed Mater 2016; 59:519-526. [PMID: 27018832 DOI: 10.1016/j.jmbbm.2016.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/08/2016] [Accepted: 03/10/2016] [Indexed: 10/22/2022]
Abstract
The purpose of this study was to quantify the frequency dependent viscoelastic properties of two types of spinal posterior dynamic stabilisation devices. In air at 37°C, the viscoelastic properties of six BDyn 1 level, six BDyn 2 level posterior dynamic stabilisation devices (S14 Implants, Pessac, France) and its elastomeric components (polycarbonate urethane and silicone) were measured using Dynamic Mechanical Analysis. The viscoelastic properties were measured over the frequency range 0.01-30Hz. The BDyn devices and its components were viscoelastic throughout the frequency range tested. The mean storage stiffness and mean loss stiffness of the BDyn 1 level device, BDyn 2 level device, silicone component and polycarbonate urethane component all presented a logarithmic relationship with respect to frequency. The storage stiffness of the BDyn 1 level device ranged from 95.56N/mm to 119.29N/mm, while the BDyn 2 level storage stiffness ranged from 39.41N/mm to 42.82N/mm. BDyn 1 level device and BDyn 2 level device loss stiffness ranged from 10.72N/mm to 23.42N/mm and 4.26N/mm to 9.57N/mm, respectively. No resonant frequencies were recorded for the devices or its components. The elastic property of BDyn 1 level device is influenced by the PCU and silicone components, in the physiological frequency range. The viscoelastic properties calculated in this study may be compared to spinal devices and spinal structures.
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Affiliation(s)
- Bernard M Lawless
- Department of Mechanical Engineering, School of Engineering, University of Birmingham, United Kingdom
| | - Spencer C Barnes
- Department of Mechanical Engineering, School of Engineering, University of Birmingham, United Kingdom
| | - Daniel M Espino
- Department of Mechanical Engineering, School of Engineering, University of Birmingham, United Kingdom
| | - Duncan E T Shepherd
- Department of Mechanical Engineering, School of Engineering, University of Birmingham, United Kingdom.
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27
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Barnes SC, Lawless BM, Shepherd DET, Espino DM, Bicknell GR, Bryan RT. Viscoelastic properties of human bladder tumours. J Mech Behav Biomed Mater 2016; 61:250-257. [PMID: 27082128 DOI: 10.1016/j.jmbbm.2016.03.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/10/2016] [Accepted: 03/16/2016] [Indexed: 12/21/2022]
Abstract
The urinary bladder is an organ which facilitates the storage and release of urine. The bladder can develop tumours and bladder cancer is a common malignancy throughout the world. There is a consensus that there are differences in the mechanical properties of normal and malignant tissues. However, the viscoelastic properties of human bladder tumours at the macro-scale have not been previously studied. This study investigated the viscoelastic properties of ten bladder tumours, which were tested using dynamic mechanical analysis at frequencies up to 30Hz. The storage modulus ranged between 0.052MPa and 0.085MPa while the loss modulus ranged between 0.019MPa and 0.043MPa. Both storage and loss moduli showed frequency dependent behaviour and the storage modulus was higher than the loss modulus for every frequency tested. Viscoelastic properties may be useful for the development of surgical trainers, surgical devices, computational models and diagnostic equipment.
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Affiliation(s)
- S C Barnes
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - B M Lawless
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - D E T Shepherd
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom.
| | - D M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - G R Bicknell
- Institute of Cancer & Genomic Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - R T Bryan
- Institute of Cancer & Genomic Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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28
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Sadeghi H, Espino DM, Shepherd DET. Variation in viscoelastic properties of bovine articular cartilage below, up to and above healthy gait-relevant loading frequencies. Proc Inst Mech Eng H 2016; 229:115-23. [PMID: 25767149 PMCID: PMC4456430 DOI: 10.1177/0954411915570372] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The aim of this study was to determine the variation in viscoelastic properties of femoral head bovine articular cartilage, on-bone, over five orders of magnitude of loading frequency. These frequencies ranged from below, up to and above healthy gait-relevant frequencies, using<1, 1–5 and 10 Hz, respectively. Dynamic mechanical analysis was used to measure storage and loss stiffness. A maximum compressive force of 36 N was applied through a chamfered-end, 5.2-mm-diameter, indenter. This induced a maximum nominal stress of 1.7 MPa. The ratio of storage to loss stiffness increased from near parity (2.5) at low frequencies to 11.4 at 10 Hz. This was the result of a significant logarithmic increase (p < 0.05) in storage stiffness with frequency, from 367 N/mm (0.001 Hz) up to 1460 N/mm (10 Hz). In contrast, the loss stiffness remained approximately constant. In conclusion, viscoelastic properties of articular cartilage measured at frequencies below those of gait activities are poor predictors of its relevant dynamic mechanical behaviour.
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Affiliation(s)
- Hamid Sadeghi
- School of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Daniel M Espino
- School of Mechanical Engineering, University of Birmingham, Birmingham, UK
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29
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Lodder J, Verkerke GJ, Delemarre BJ, Dodou D. Morphological and mechanical properties of the posterior leaflet chordae tendineae in the mitral valve. Proc Inst Mech Eng H 2015; 230:77-84. [PMID: 26645804 DOI: 10.1177/0954411915621093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 09/21/2015] [Indexed: 11/16/2022]
Abstract
A number of studies have investigated the morphological and mechanical properties of the chordae tendineae of the mitral valve, providing comparisons between basal, marginal, and strut chordae and between chordae at the anterior and posterior leaflets. This study contributes to the literature by comparing the failure load of the chordae tendineae attached to the three posterior leaflet scallops, the anterolateral scallop (P1), middle scallop (P2), and posteromedial scallop (P3) of the mitral valve. In all, 140 chordae isolated from 23 porcine hearts were tested. First, the cross-sectional diameters of all branches in each chorda were measured using a microscope. Next, after positioning the chorda in a tensile testing machine, a preload of 0.2 N was applied, and the chordal length was measured. Cyclic loading between 0 and 0.3 N, 10 times with a speed of 1.5 mm/s, was conducted, after which the machine travelled at 1.5 mm/s until the chorda broke. We found that P2 chordae were thicker than P1 and P3 chordae and longer than P1 chordae. P2 chordae failed at significantly higher loads than P1 and P3 chordae. For all three types of chordae, almost half of the failures occurred at the chordal branch that was closest to the leaflet.
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Affiliation(s)
- Joost Lodder
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands Department of Rehabilitation Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Gijsbertus J Verkerke
- Department of Rehabilitation Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands Department of Biomechanical Engineering, Faculty of Engineering Technology, University of Twente, Enschede, The Netherlands
| | - Ben Jm Delemarre
- Department of Cardiology, Haga Hospital, The Hague, The Netherlands
| | - Dimitra Dodou
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
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30
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Wong WLE, Joyce TJ, Goh KL. Resolving the viscoelasticity and anisotropy dependence of the mechanical properties of skin from a porcine model. Biomech Model Mechanobiol 2015; 15:433-46. [PMID: 26156308 DOI: 10.1007/s10237-015-0700-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 06/29/2015] [Indexed: 11/29/2022]
Abstract
The mechanical response of skin to external loads is influenced by anisotropy and viscoelasticity of the tissue, but the underlying mechanisms remain unclear. Here, we report a study of the main effects of tissue orientation (TO, which is linked to anisotropy) and strain rate (SR, a measure of viscoelasticity), as well as the interaction effects between the two factors, on the tensile properties of skin from a porcine model. Tensile testing to rupture of porcine skin tissue was conducted to evaluate the sensitivity of the tissue modulus of elasticity (E) and fracture-related properties, namely maximum stress (σU) and strain (εU) at σU, to varying SR and TO. Specimens were excised from the abdominal skin in two orientations, namely parallel (P) and right angle (R) to the torso midline. Each TO was investigated at three SR levels, namely 0.007-0.015 s(-1) (low), 0.040 s(-1) (mid) and 0.065 s(-1) (high). Two-factor analysis of variance revealed that the respective parameters responded differently to varying SR and TO. Significant changes in the σU were observed with different TOs but not with SR. The εU decreased significantly with increasing SR, but no significant variation was observed for different TOs. Significant changes in E were observed with different TOs; E increased significantly with increasing SR. More importantly, the respective mechanical parameters were not significantly influenced by interactions between SR and TO. These findings suggest that the trends associated with the changes in the skin mechanical properties may be attributed partly to differences in the anisotropy and viscoelasticity but not through any interaction between viscoelasticity and anisotropy.
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Affiliation(s)
- W L E Wong
- NUInternational Singapore Pte Ltd, Singapore, 569830, Singapore.,School of Mechanical and Systems Engineering, Newcastle University, Newcastle Upon Tyne, NE1 7RU, England, UK
| | - T J Joyce
- School of Mechanical and Systems Engineering, Newcastle University, Newcastle Upon Tyne, NE1 7RU, England, UK
| | - K L Goh
- NUInternational Singapore Pte Ltd, Singapore, 569830, Singapore. .,School of Mechanical and Systems Engineering, Newcastle University, Newcastle Upon Tyne, NE1 7RU, England, UK.
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31
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Frequency dependent viscoelastic properties of porcine bladder. J Mech Behav Biomed Mater 2015; 42:168-76. [DOI: 10.1016/j.jmbbm.2014.11.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/10/2014] [Accepted: 11/18/2014] [Indexed: 12/30/2022]
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32
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Viscoelastic properties of bovine knee joint articular cartilage: dependency on thickness and loading frequency. BMC Musculoskelet Disord 2014; 15:205. [PMID: 24929249 PMCID: PMC4068975 DOI: 10.1186/1471-2474-15-205] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 06/10/2014] [Indexed: 11/17/2022] Open
Abstract
Background The knee is an incongruent joint predisposed to developing osteoarthritis, with certain regions being more at risk of cartilage degeneration even in non-osteoarthrosed joints. At present it is unknown if knee regions prone to cartilage degeneration have similar storage and/or loss stiffness, and frequency-dependent trends, to other knee joint cartilage. The aim of this study was to determine the range of frequency-dependent, viscoelastic stiffness of articular cartilage across the bovine knee joint. Such changes were determined at frequencies associated with normal and rapid heel-strike rise times. Methods Cartilage on bone, obtained from bovine knee joints, was tested using dynamic mechanical analysis (DMA). DMA was performed at a range of frequencies between 1 and 88 Hz (i.e. relevant to normal and rapid heel-strike rise times). Viscoelastic stiffness of cartilage from the tibial plateau, femoral condyles and patellar groove were compared. Results For all samples the storage stiffness increased, but the loss stiffness remained constant, with frequency. They were also dependent on cartilage thickness. Both the loss stiffness and the storage stiffness decreased with cartilage thickness. Femoral condyles had the thinnest cartilage but had the highest storage and loss stiffness. Tibial plateau cartilage not covered by the meniscus had the thickest cartilage and lowest storage and loss stiffness. Conclusion Differences in regional thickness of knee joint cartilage correspond to altered frequency-dependent, viscoelastic stiffness.
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