Dynamic Changes of the Mitral Valve Annulus

The appreciation of mitral valve prolapse (MVP) has evolved from clinical recognition1 to surgical classification to guide repair,2 echocardiographic analysis, and specificity3,4 with 3-dimensional (3D) depiction5 and most recently genetic and molecular studies.6,7 Two manifestations of degenerative mitral valve disease (DMVD), the main cause of MVP, have been recognized: diffuse myxomatous degeneration (DMD) with involvement of multiple scallops of both leaflets and fibroelastic deficiency (FED), with generally thin leaflets except for myxoid degeneration of one or a few scallops of a single leaflet, generally the posterior.8 From both mechanistic and surgical perspectives, it remains unresolved whether these are 2 distinct phenotypes or a spectrum, and whether the localized thickening in FED is primary or secondary to the adjacent turbulent blood flow emerging from a scallop with deficient chordal restraint.See Article by Clavel et al Clavel et al,9 in this issue of Circulation: Cardiovascular Imaging , have now contributed information from dynamic quantitative 3D echocardiography relevant to this question in patients undergoing reconstructive surgery that allows visual classification. Despite comparable mitral regurgitation (MR) severity consistent with surgical selection, in addition to previously described static anatomic characteristics, namely enlarged annulus and excess valvular tissue,5 cyclic annular dynamics are blunted in DMD and systolic leaflet area changes are reduced in FED. These findings raise the possibility of primary alterations of the mitral annulus and biomechanical differences in the leaflet tissue,10,11 with excess distensible tissue in DMD versus relatively deficient and less extensible tissue in FED. These variations could reveal differences in mechanism and require differences in surgical approach.DMVD can affect any of the mitral apparatus components: the leaflets, chordae tendineae, papillary muscles, and annulus. Whether …