Biaxial quantification of passive porcine myocardium elastic properties by region

Ṋemavhola, Fulufhelo

doi:10.5267/j.esm.2017.6.003

Cited by 21 publications

(24 citation statements)

References 15 publications

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“…Biaxial mechanical testing remains the gold standard for evaluation of passive tissue-level RVFW biomechanical properties and has been employed in ex-vivo studies in small and large animal models (Valdez-Jasso et al, 2012;Hill et al, 2014;Javani et al, 2016;Nemavhola, 2017), as well as excised tissues from human donors (Sommer et al, 2015). While ex-vivo biaxial testing has been previously employed for characterization of active biomechanical properties of LV myocardium (Lin and Yin, 1998), biaxial studies on the RV have been mostly focused on the passive components of RVFW biomechanics.…”

Section: Effects Of Pah On Biaxial Mechanical Properties Of the Rvfwmentioning

confidence: 99%

“…While SHG microscopy provides high fidelity information on the microarchitecture of ventricular fibers, this technique has an imaging depth of <1.2 mm (Sommer et al, 2015). This limits SHG's potential to study the full-thickness transmural fiber orientations of intact RV myocardium from large animal models and human donors, which are generally >2 mm thick (Javani et al, 2016;Nemavhola, 2017). RV fibers demonstrate counterclockwise rotations throughout the RVFW (Hill et al, 2014), with collagen fibers running nearly parallel to myofibers (Sharifi Kia et al, 2020).…”

Section: Pah-induced Transmural Rv Fiber Reorientationmentioning

confidence: 99%

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Current Understanding of the Right Ventricle Structure and Function in Pulmonary Arterial Hypertension

2021

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Pulmonary arterial hypertension (PAH) is a disease resulting in increased right ventricular (RV) afterload and RV remodeling. PAH results in altered RV structure and function at different scales from organ-level hemodynamics to tissue-level biomechanical properties, fiber-level architecture, and cardiomyocyte-level contractility. Biomechanical analysis of RV pathophysiology has drawn significant attention over the past years and recent work has found a close link between RV biomechanics and physiological function. Building upon previously developed techniques, biomechanical studies have employed multi-scale analysis frameworks to investigate the underlying mechanisms of RV remodeling in PAH and effects of potential therapeutic interventions on these mechanisms. In this review, we discuss the current understanding of RV structure and function in PAH, highlighting the findings from recent studies on the biomechanics of RV remodeling at organ, tissue, fiber, and cellular levels. Recent progress in understanding the underlying mechanisms of RV remodeling in PAH, and effects of potential therapeutics, will be highlighted from a biomechanical perspective. The clinical relevance of RV biomechanics in PAH will be discussed, followed by addressing the current knowledge gaps and providing suggested directions for future research.

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Section: Effects Of Pah On Biaxial Mechanical Properties Of the Rvfwmentioning

confidence: 99%

Section: Pah-induced Transmural Rv Fiber Reorientationmentioning

confidence: 99%

Current Understanding of the Right Ventricle Structure and Function in Pulmonary Arterial Hypertension

2021

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“…Testing remains the most common modality of mechanical analysis for biological [1][2][3][4][5][6] and other soft materials [7]; however, biaxial testing enables a more comprehensive understanding of these materials' mechanical behaviour, which is also necessitated by the fact that heart muscle is spatially heterogenous. The physiological functioning of myocardial muscles involves a complex force pattern in which biaxial tensile and compressive forces during diastole and systole phases are combined with forces in the third dimension [8,9].…”

Section: Introductionmentioning

confidence: 99%

“…Besides, other studies [12] further recommended that for cardiac tissue constitutive modelling, more uniaxial or biaxial tensile tests, identification of viscoelastic properties in various time scales, use of pressure-volume curves be carried out, and that there is need for correlating the passive biomechanical cardiac tissue properties with microstructural observations. Previous studies have been conducted to understand the tissue mechanics of healthy myocardia [13] to assist in the advancement of heart-specific computational models [1, 3,[14][15][16][17][18][19] and development of new materials for use in diagnosing and treatment of coronary illnesses. This study is aimed at investigating cross-direction and cross-wall variations in infarcted rat myocardium.…”

Section: Introductionmentioning

confidence: 99%

Determination of Cross-directional and Cross-Wall Variations of Passive Biaxial Mechanical Properties of Rat Myocardium

Ngwangwa¹,

Ṋemavhola²,

Pandelani³

et al. 2021

Preprint

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Heart myocardia are critical to the facilitation of heart pumping and blood circulating around the body. The biaxial mechanical testing of the Left Ventricle (RV) is utilised to build the computa-tional model of the whole heart with little importance given to the unique mechanical properties of Right Ventricle (RV) and Mid-wall (MDW). Most of those studies focussed on the LV of the heart, and then apply the obtained characteristics with a few modifications to the right side of the heart. However, that view has been contested over time with the realisation that the right side of the heart possesses its own unique mechanical properties that are widely distinct from that of the left side of the heart. This paper is aimed at reporting and evaluating the passive mechanical property dif-ferences in the three main walls of the rat heart based on biaxial tensile test data. Fifteen mature Wistar rats weighing 225 ± 25 g were euthanised by inhalation of 5 % halothane. The hearts were excised after which all the top chambers comprising the two atria, pulmonary and vena cava trunks, aorta and valves are all dissected out. Then 5 x 5 mm sections from the middle of each wall were carefully dissected with a surgical knife to avoid over-prestraining the specimens. The specimens were subjected tensile test. The elastic moduli, peak stresses in the toe region and stresses at 40 % strain, anisotropy indices as well as the stored strain energy in the toe and linear region up to 40 % strain are used for statistical significance tests. The following are the main findings of this study: (1) LV and MDW tissues have relatively shorter toe regions of 10 - 15 % strain as compared to RV tissue whose toe region extends up to twice as much as that (2) LV tissues have higher strain energy storage in the linear region despite being lower in stiffness than the RV (3) the MDW has the highest strain energy storage along both directions which might be directly related to its high level of anisotropy. These findings, though for a specific animal species at similar age and around the same body mass, emphasize the importance of application of wall specific material parameters to obtain accurate ventricular hyperelastic models. The findings further enhance our understanding of the desired mechanical behaviour of the different ventricle walls.

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“…Mechanical properties of soft tissues are vital in the devevelopment of accurate and reliable computational models [1][2][3][4]. Tendons are normally understood to have strong tissues that are connected together that transfers muscle forces to the bones [5,6].…”

Section: Introductionmentioning

confidence: 99%

The Application of Standard Nonlinear Solid Material Models in Modelling the Tensile Behaviour of the Supraspinatus Tendon

Ngwangwa¹,

Pandelani²,

Ṋemavhola³

2021

Preprint

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Tendons transmit forces from muscles to bones through joints. Typically, tendons and muscles work together to innovate a particular type of motion. Therefore, in order for the tendons to find attachment to the bones, they are naturally adapted as much thinner strands than the muscles that they serve. Thus, they are often subjected to much higher stresses than the muscles that they actually serve in any given action. As a result, tendons are susceptible to injuries that may lead to a permanent dysfunction in joint mobility due to the fact that the scar tissue that forms after healing does not often have the same mechanical properties of the original tissue. It is, therefore, very important to understand the mechanical response of tendons. This paper examines the performances of two viscoelastic standard nonlinear models in modelling the elastic and plastic behaviour of the tendon in the light of a well-known hyperelastic Yeoh model. The use of the Yeoh model is more for validating the performances of the viscoelastic models within the elastic region rather than for comparison purposes. Yeoh model’s selection was based on its superior performance in modelling the elastic phase of soft tissue as reported in previous studies combined with its simplicity. The results show that the two standard nonlinear solid models perform extremely well both in fitting accuracies and in correlating stress results. The most promising result is the fact that the two standard nonlinear models can model tendon behaviour in the nonlinear plastic region. It is also noted that the two standard nonlinear models are physically insightful since their optimisation parameters can be easily interpreted in terms of tendon elasticity and viscoelastic parameters.

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Biaxial quantification of passive porcine myocardium elastic properties by region

Cited by 21 publications

References 15 publications

Current Understanding of the Right Ventricle Structure and Function in Pulmonary Arterial Hypertension

Current Understanding of the Right Ventricle Structure and Function in Pulmonary Arterial Hypertension

Determination of Cross-directional and Cross-Wall Variations of Passive Biaxial Mechanical Properties of Rat Myocardium

The Application of Standard Nonlinear Solid Material Models in Modelling the Tensile Behaviour of the Supraspinatus Tendon

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