Mitral Saddle Shape Preservation Improves Valvuloplasty

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DESCRIPTION (provided by applicant): During the past thirty years Carpentier has pioneered and standardized surgical techniques that allow reliable repair of mitral valves with all types of leaflet, chordal and annular deformities. Use of these techniques has produced good results at centers all over the world. Although the durability of these repairs has been acceptable there is a 10 to 16% long-term failure rate. Reported modes of failure implicate mechanical stress as an etiologic factor. Imaging techniques in humans and animals have shown the mitral annulus to have a pronounced saddle shape; this shape is conserved across mammalian species. State-of-the-art mathematical modeling indicates that this saddle shape imparts curvature to the leaflets, minimizing leaflet stress and resulting strain. Most established mitral valve repair techniques include placement of a flat annuloplasty ring. While a flat ring improves early valve competence by reducing annular area and improving leaflet coaptation, annular flattening may reduce leaflet curvature and produce unnecessary stress and strain on leaflet tissue, chordae tendenae and repair suture lines, limiting repair durability. We hypothesize that saddle-shape annuloplasty will diminish leaflet stress when compared with standard flat annuloplasty, Three-dimensional echocardiography will be used to assess the effect of annuloplasty ring shape on normal leaflet curvature in an ovine model. In addition, sonomicrometry array localization, a technique for cardiac imaging and strain measurement, will be used to assess the effect of annuloplasty ring shape on mitral valve leaflet strain throughout the cardiac cycle. Data from these two techniques will allow a quantitative assessment of the mechanism linking annular shape, leaflet curvature, and leaflet strain. An understanding of this relationship will allow a more rational design of annuloplasty rings, improving the longevity of currently established valve repair techniques.