Mitral valvuloplasty: when the art of repair meets the biological science.

The majority of approaches currently described and practiced in mitral repair surgery result in the vertical immobilization of the posterior leaflet, with the anterior leaflet striving to produce an adequate coaptation. Despite the satisfactory hemodynamic outcome and disappearance of mitral regurgitation, this non-physiological situation results in a redistribution of forces within the mitral apparatus with an increased stress on the leaflets. Biological evidences are pointing at the ability of the valvular interstitial cells to actively respond to biomechanical changes, switching their phenotype and producing different patterns of extracellular matrix proteins. This biological event translates to changes in the anatomical and mechanical properties of the leaflets, leading to an increased stiffening and a susceptibility to develop calcification. These concepts find a clinical reflex in reports on the long-term thickening and calcification of the leaflets after mitral repair, and in the leaflets remodeling phenomena described in chronically dilated ventricles. The importance of respecting the physiological movement and dynamics of the leaflets when performing a valvuloplasty is underlined, and a potential pharmacological modulation of the aforementioned biological processes to ameliorate long-term results of the repair is hypothesized.