Mechanics of the mitral valve: in vitro studies

Improved knowledge of mitral valve (MV) mechanics is essential to understanding normal MV function and design; however, there is limited information about the mechanical properties of the MV during physiologic loading. These studies utilized different techniques to characterize the mechanical properties of the MV. Histological techniques were used to examine collagen, elastin, and cellular distribution on the chordae. Vessels were observed in both the longitudinal and circumferential directions. The presence of vessels characterize the chordae as complex living components that must work with the PM and MV leaflets to prevent MV prolapse and regurgitation. Force and strain distribution on the chordae and anterior leaflet were measured in a pathological papillary muscle (PM) positions. Tension distribution results showed that the intermediate chords on their respective leaflets. The slack PM position led to a delay in complete valve closure and more rapid leaflet loading in late systole. The chordae showed physiological strains, reaching maximum strain during valve closure. The in vitro studies demonstrated that chordal force distribution and valve function depend on the mechanical environment of the valve and the geometric relationships between its components.