Surgery for Acquired Cardiovascular Disease (ACD)
Mechanical properties of myxomatous mitral valves,☆☆

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Abstract

Objective: We sought to characterize the mechanical properties of normal and myxomatous mitral valve tissues. Methods: We tested 113 mitral valve sections from patients undergoing mitral valve repair or replacement for myxomatous mitral valve prolapse and sections from 33 normal valves obtained at autopsy. Results: Myxomatous mitral valve leaflets were more extensible than normal leaflets when tested parallel to the free edge (41.2% ± 18.5% vs 17.3% ± 6.7% circumferential strain [mean ± SD]; P ||.001), as well as perpendicular to the free edge (43.2% ± 19.4% vs 17.3% ± 6.7% radial strain; P ||.001). Myxoid leaflets were less stiff circumferentially (4.0 ± 1.6 vs 6.1 ± 1.4 kN/m; P ||.001) and radially (4.5 ± 1.1 vs 6.1 ± 1.4 kN/m; P ||.001) than normal leaflets. Leaflet strength, however, was similar in both groups. Conclusions: Myxomatous mitral valve leaflets are physically and mechanically different from normal mitral valve leaflets. They are more extensible and less stiff. Compared with chordae examined previously, however, they are affected much less. Myxomatous mitral valve disease may therefore affect the collagen in the chordae more severely than that in the leaflets.

J Thorac Cardiovasc Surg 2001;122:955-62

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This work was supported in part by research grants from the northeast Ohio and national branches of The American Heart Association and by The Mareb Foundation, Inc, Basking Ridge, NJ.

☆☆

Address for reprints: Ivan Vesely, PhD, Department of Biomedical Engineering/ND20, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195 (E-mail: [email protected] ).