A two-layered mechanical model of the rat esophagus. Experiment and theory

BioMedical Engineering OnLine

Yanhua Fan¹  Hans Gregersen²  Ghassan S Kassab³ 

[1] Institute of Experimental Clinical Research, Skejby Hospital, Aarhus, Denmark

[2] Haukeland University Hospital, Bergen, Norway

[3] Department of Biomedical Engineering, UC Irvine, Irvine, California

关键词: Zero-stress state;    Opening angle;    Muscle layer;    Mucosa-submucosa layer;    Biomechanics;   

Others  :  798851
DOI  :  10.1186/1475-925X-3-40

 received in 2004-07-15, accepted in 2004-11-01,  发布年份 2004

【 摘 要 】

Background

The function of esophagus is to move food by peristaltic motion which is the result of the interaction of the tissue forces in the esophageal wall and the hydrodynamic forces in the food bolus. The structure of the esophagus is layered. In this paper, the esophagus is treated as a two-layered structure consisting of an inner collagen-rich submucosa layer and an outer muscle layer. We developed a model and experimental setup for determination of elastic moduli in the two layers in circumferential direction and related the measured elastic modulus of the intact esophagus to the elastic modulus computed from the elastic moduli of the two layers.

Methods

Inflation experiments were done at in vivo length and pressure-diameters relations were recorded for the rat esophagus. Furthermore, the zero-stress state was taken into consideration.

Results

The radius and the strain increased as function of pressure in the intact as well as in the individual layers of the esophagus. At pressures higher than 1.5 cmH₂O the muscle layer had a larger radius and strain than the mucosa-submucosa layer. The strain for the intact esophagus and for the muscle layer was negative at low pressures indicating the presence of residual strains in the tissue. The stress-strain curve for the submucosa-mucosa layer was shifted to the left of the curves for the muscle layer and for the intact esophagus at strains higher than 0.3. The tangent modulus was highest in the submucosa-mucosa layer, indicating that the submucosa-mucosa has the highest stiffness. A good agreement was found between the measured elastic modulus of the intact esophagus and the elastic modulus computed from the elastic moduli of the two separated layers.

【 授权许可】

   
2004 Fan et al; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

【 参考文献 】

• [1]Gregersen H, Lee TC, Chien S, Skalak R, Fung YC: Strain distribution in the layered wall of the esophagus. J Biomech Eng 1999, 121:442-448.
• [2]Gregersen H: Residual strain in the gastrointestinal tract: a new concept. Neurogastroenterol Motil 2000, 12:411-414.
• [3]Lu X, Gregersen H: Regional distribution of axial strain and circumferential residual strain in the layered rabbit oesophagus. J Biomech 2001, 34:225-233.
• [4]Gregersen H, Kassab GS: Biomechanics of the gastrointestinal tract. Neurogastroenterol Motil 1996, 8:277-297.
• [5]Matsumoto T, Hayashi K: Stress and strain distribution in hypertensive and normotensive rat aorta considering residual strain. J Biomech Eng 1996, 118:62-73.
• [6]Peterson SJ, Okamoto RJ: Effect of residual stress and Heterogeneity on circumferential stress in the arterial wall. J Biomech Eng 2000, 122:454-456.
• [7]Fung YC: Biomechanics: Motion, Flow, Stress and Growth. New York: Springer Verlag; 1990.
• [8]Flügge W: Stresses in shells Berlin. Springer Verlag; 1960.
• [9]Arndorfer RC, Stef JJ, Dodds WJ, Linehan JH, Hogan WT: Improved infusion system for intraluminal esophageal manometry. Gastroenterology 1977, 73:23-27.
• [10]Christensen J: The esophagus. In In Physiology of the Gastrointestinal Tract. Volume 1. 2nd edition. Edited by Johnson LR, Christensen J, Jackson MJ, Jacobson ED, Walsh JH. New York: Raven Press; 1987::595-612.
• [11]Humphries TJ, Castell DO: Pressure profile of esophageal peristalsis in normal humans as measured by direct intraesophageal transducers. Am J Dig Dis 1977, 22:641-646.
• [12]Li M, Brasseur JG, Kern MK, Dodds WJ: Viscosity measurements of barium sulfate mixtures for use in motility studies of the pharynx and esophagus. Dysphagia 1992, 7:17-30.
• [13]Ravinder KM, Ren J, McCallum RW, Shaffer HA, Sluss J: Modulation of feline oesophageal contractions by bolus volume and outflow obstruction. Am J Physiol 1990, 258:G208-G215.
• [14]Ren J, Massey BT, Dodds WJ, Kern MK, Brasseur JG, Shaker R, Harrington SS, Hogan WJ, Arndorfer RC: Determinants of the bolus pressure during esophageal peristaltic bolus transport. Am J Physiol 1993, 264:G407-G413.
• [15]Christensen J, Freeman BW, Miller JK: Some physiological characteristics of the esophagogastric junction in the opossum. Gastroenterology 1973, 64:1119-1125.
• [16]Lu X, Yang J, Zhao J, Gregersen H, Kassab GS: Shear modulus of coronary arteries Contribution of media and adventitia. Am J Physiol Heart Circ Physiol 2003, 285:H1966-H1975.
• [17]Berry J, Rachev A, Moore JE jr, Meister JJ: Analysis of the effect of a non-circular two-layer stress-free state on arterial wall stress. Proceedings of IEEE, EMBS, Paris 1992, 65-66.
• [18]Demiray H, Vito RP: A layered cylindrical shell model for an aorta. Int J Eng Sci 1991, 29:47-54.
• [19]Maltzahn WWV, Besdo D, Wiemer W: Elastic properties of arteries. A nonlinear two-layer cylindrical model. J Biomech 1981, 14:389-397.
• [20]Maltzahn WWV, Warringar RG, Keitzer WF: Experimental measurement of soft elastic properties of media and adventitia of bovine carotid arteries. J Biomech 1984, 17:839-848.
• [21]Rachev A: Theoretical study of the effect of stress-dependent remodeling on arterial geometry under hypertensive conditions. J Biomech 1997, 30:819-827.
• [22]Greenwald SE, Moore JEJ, Rachev A, Meister JJ: Experimental investigation of the distribution of residual strains in the artery wall. J Biomech Eng 1997, 119:438-444.
• [23]Taber LA, Humphrey JD: Stress-modulated growth, residual stress and vascular heterogeneity. J Biomech Eng 2001, 123:528-535.
• [24]Fung YC: Elasticity of soft tissues in simple elongation. Am J Physiol 1967, 213:1532-1544.
• [25]Xie JP, Zhou JB, Fung YC: Bending of blood vessel wall: stress-strain laws of the intima-media and adventitial layers. J Biomech Eng 1995, 117:136-145.
• [26]Yu QL, Zhou JB, Fung YC: Neutral axis location in bending and Young's modulus of different layers of arterial wall. Am J Physiol 1993, 269:H52-H60.
• [27]Villadsen GE, Storkholm J, Zachariae H, Hendel L, Bendtsen F, Gregersen H: Oesophageal pressure-cross-sectional area distributions and secondary peristalsis in relation to subclassification of systemic sclerosis. Neurogastroenterol Motil 2001, 13:199-210.
• [28]Villadsen GE, Storkholm JH, Hendel L, Vilstrup H, Gregersen H: Impedance planimetric characterization of esophagus in systemic sclerosis patients with severe involvement of esophagus. Dig Dis Sci 1997, 42:2317-26.