Mechanical properties of basal and marginal mitral valve chordae tendineae

The authors determined the stress/strain characteristics of basal and marginal mitral valve chordae tendineae. The chordae exhibit a nonlinear stress/strain behavior typical of biologic materials, with a discrete transition in the tensile elastic modulus. The post-transition moduli for both basal and marginal chordae are greater than the pretransition values by a factor of approximately 10. In addition, the stress carried by the marginal chordae is higher than that supported by the basal ones at all recorded strains, indicating the marginal chordae are stiffer than the basal chordae. The authors determined the number and distribution of chordal insertions, and found a marginal to basal insertion ratio of almost 2 to 1. The implication is that it may be possible surgically to remove basal chordae without seriously compromising mitral valve function.