Directional, Regional, and Layer Variations of Mechanical Properties of Esophageal Tissue and its Interpretation Using a Structure-Based Constitutive Model

Yang, Wenyu; Fung, T. C.; Chian, Kerm Sin; Chong, C. K.

doi:10.1115/1.2187033

Cited by 56 publications

(51 citation statements)

References 23 publications

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“…Based on the same framework, a similar constitutive model was used to describe the mechanical properties of oesophageal tissue by Yang et al (2006). As with the model in Zulliger et al (2004a), they used an engagement stretch associated with the un-crimping of collagen fibres.…”

Section: (B) Modelling Other Soft Tissuesmentioning

confidence: 99%

Constitutive modelling of arteries

2010

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This review article is concerned with the mathematical modelling of the mechanical properties of the soft biological tissues that constitute the walls of arteries. Many important aspects of the mechanical behaviour of arterial tissue can be treated on the basis of elasticity theory, and the focus of the article is therefore on the constitutive modelling of the anisotropic and highly nonlinear elastic properties of the artery wall. The discussion focuses primarily on developments over the last decade based on the theory of deformation invariants, in particular invariants that in part capture structural aspects of the tissue, specifically the orientation of collagen fibres, the dispersion in the orientation, and the associated anisotropy of the material properties. The main features of the relevant theory are summarized briefly and particular forms of the elastic strain-energy function are discussed and then applied to an artery considered as a thickwalled circular cylindrical tube in order to illustrate its extension-inflation behaviour. The wide range of applications of the constitutive modelling framework to artery walls in both health and disease and to the other fibrous soft tissues is discussed in detail. Since the main modelling effort in the literature has been on the passive response of arteries, this is also the concern of the major part of this article. A section is nevertheless devoted to reviewing the limited literature within the continuum mechanics framework on the active response of artery walls, i.e. the mechanical behaviour associated with the activation of smooth muscle, a very important but also very challenging topic that requires substantial further development. A final section provides a brief summary of the current state of arterial wall mechanical modelling and points to key areas that need further modelling effort in order to improve understanding of the biomechanics and mechanobiology of arteries and other soft tissues, from the molecular, to the cellular, tissue and organ levels.

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Section: (B) Modelling Other Soft Tissuesmentioning

confidence: 99%

Constitutive modelling of arteries

2010

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“…In our previous study [9] , it was proved that the porcine esophagus has similarities with the human being's esophagus in terms of both axial length (25-30 cm for the pig 3-4 mo old vs 25 cm for an adult) and tensile strengths (circumferential and axial strengths are 1.2 and 3.7 MPa for the muscle and 1.6 and 8.7 MPa for the mucosasubmucosa [9] vs 1.4 and 2.2 MPa for the entire wall). Since detailed geometrical and mechanical parameters for the human's esophagus were not available for our simulation, those for the porcine esophagus were taken as the representative so that the effects of the variations in mechanical properties on the efficiency of food transport could be examined.…”

Section: Finite Element Modelmentioning

confidence: 89%

“…A structure-based constitutive model, which has been successfully applied for the esophageal tissue [9] , was adopted in the simulation. With this model, the esophageal wall was modeled as an isotropic matrix of elastin reinforced with collagen fibers.…”

Section: Fmentioning

confidence: 99%

Finite element simulation of food transport through the esophageal body

Yang

Fung²,

Chian³

et al. 2007

WJG

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The transit of food the bolus through the esophageal body depends on the properties of the bolus as well as the positions of the thorax when the swallow occurs. If the food is fluid-like and a person stands upright, it only takes 2-3 s for the food to approach the lower esophageal sphincter (LES). In this case, the bolus moves mainly under the influence of gravity. When either or both the content of bolus and the position of the thorax reduce the effects of gravity, the peristaltic mechanism plays the most important role for the bolus transport. The muscle contraction is first inhibited to allow the bolus to distend and fill the esophageal lumen. This inhibition is followed by the active muscle contractions near the bolus tail to maintain the lumen closure and propel the bolus towards the stomach. The contraction wave travels at a speed of 1-4 cm/s and duration of 5-10 s is required for the bolus to reach the LES, when the muscle at LES stats to relax and LES opens. The LES remains open for 5-10 s during which the food content is emptied from the esophagus to the stomach. Thus, food transport is an interactive process between the esophageal tissue, food bolus and muscle activity.It is well known that the stress distribution within the esophageal wall is important to understand the mechanics-function relationship of the esophagus. The stress distribution under the physiological state has been widely investigated in the literature [1,2] . However, the effect of food bolus on tissue structure has usually been represented by a luminal pressure imposed on the internal surface of the esophageal tube while the bolus and the interaction between the tissue and bolus have been ignored. On the other hand, in the study conducted by Li et al [3] , a mathematical model was established to simulate the fluid (food bolus) flow within the esophageal lumen. By applying the lubrication theory [4] , the intraluminal AbstractThe peristaltic transport of swallowed material in the esophagus is a neuro-muscular function involving the nerve control, bolus-structure interaction, and structuremechanics relationship of the tissue. In this study, a finite element model (FEM) was developed to simulate food transport through the esophagus. The FEM consists of three components, i.e., tissue, food bolus and peristaltic wave, as well as the interactions between them. The transport process was simulated as three stages, i.e., the filling of fluid, contraction of circular muscle and traveling of peristaltic wave. It was found that the maximal passive intraluminal pressure due to bolus expansion was in the range of 0.8-10 kPa and it increased with bolus volume and fluid viscosity. It was found that the highest normal and shear stresses were at the inner surface of muscle layer. In addition, the peak pressure required for the fluid flow was predicted to be 1-15 kPa at the bolus tail. The diseases of systemic sclerosis or osteogenesis imperfecta, with the remodeled microstructures and mechanical properties, might induce the malfunction of esophageal ...

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“…Average MSEs from the curve fits were compared to the macroscopic incompressible Mooney-Rivlin (MR) and neo-Hookean (NH) models (Eqs. (14) and (15) applied to the ECM) in Fig. 8.…”

Section: Estimation Of Geometric Variables and Fibril Properties Frommentioning

confidence: 99%

“…Early efforts to model the collagen fibril component of the ECM directly integrated parameters such as fibril undulation during tension, initial orientation distribution and volume fraction of fibrils into traditional continuum models [12][13][14][15]. A direct implementation of microstructural features in fibrous networks was developed by Wang et al for battery substrate applications [16].…”

Section: Introductionmentioning

confidence: 99%