Mechanical Properties of Chordae Tendineae of the Mitral Heart Valve: Young'S Modulus, Structural Stiffness, and Effects of Aging

Young's modulus and structural stiffness were determined for chordae tendineae of the mitral valve from young (18-26 weeks) and old (over 2 years) porcine hearts. For chordae from the posterior leaflet of the valve, the Young's modulus values were significantly higher (p <0.05) for the thinner marginal chordae (59 +/- 31MPa young; 88 +/- 21 MPa old) than for the thicker basal chordae (31 +/- 4 MPa young; 28 +/- 9 MPa old). Marginal chordae (both anterior and posterior) had significantly higher (p <0.05) value for their Young's modulus in old (88 +/- 21 MPa anterior and posterior) than in young (62 +/- 17 MPa anterior, 59 +/- 18 MPa posterior) pig hearts. There was no significant difference in structural stiffness between marginal and basal (anterior and posterior leaflets) or between strut chordae (that are associated with anterior the leaflet only) and marginal and basal chordae. However, the value of structural stiffness of chordae was significantly higher (p <0.05) for old (2.2 +/- 0.2 kN/m) than for young (2.0 +/- 0.4 kN/m) chordae. These results show that aging affects the properties of chordae and that all chordae need to be included in finite element models of valve function.