Effects of collagen microstructure on the mechanics of the left ventricle.
The microstructure of the collagen sheath or weave surrounding a myocyte and the collagen struts interconnecting neighboring myocytes is incorporated into a fluid-fiber-collagen continuum description of the myocardium. The sheaths contribute to anisotropic elasticity, whereas the struts contribute to an isotropic component. Elastic moduli of the composite myocyte-sheath complex and the strut matrix are estimated from existing passive biaxial loading data from sheets of canine myocardium. The contribution of the sheath to the elasticity of the myocyte-sheath complex is critically dependent on the helical pitch angle. Calculations for a cylindrical model of the left ventricle using both a fluid-fiber and fluid-fiber-collagen stress tensor show that the collagen strut matrix tends to limit muscle fiber lengthening; increase myocardial tissue pressure during systole, with endocardial tissue pressure exceeding left ventricular pressure; decrease tissue pressure during diastole, and thus facilitate myocardial blood flow; and aid filling during ventricular relaxation by providing a suction effect that relies on a release of stored elastic energy from the previous contraction. Calculations show that this energy is stored mostly in the collagen struts.
Ohayon
J
J
Division of Research Services, National Institutes of Health, Bethesda, Maryland 20892.
Chadwick
R S
RS
D000818:Animals; D003094:Collagen / Q000502:physiology / Q000648:ultrastructure*; D004548:Elasticity; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles / Q000033:anatomy & histology; D008433:Mathematics; D008953:Models, Anatomic; D008962:Models, Theoretical; D013314:Stress, Mechanical; D016276:Ventricular Function
D003094:Collagen