Posterior mitral leaflet: new anatomical insight and review of nomenclature (mitral valve anatomy)

Objectives Previous studies described single components of the mitral valve, but somewhat lacked the spatial analysis of their relationship. Moreover, further information is necessary regarding reconstructive surgery. The current work aimed at in-depth analysis of the anatomy of the posterior mitral leaflet (PML) and its changes due to degenerative disease, completing the already existing anatomical information about PML and proposing a reorganization of the actual terminology. Methods Nine normal PMLs harvested from cadavers have been compared with 12 pathological specimens from partial resection of PML in the course of valve repair in adult patients. Dimensions of smooth and rough surfaces of the PML have been measured and compared and their dimensional relationships have been assessed; the chance of finding chordae tendineae inserting into the smooth, periannular portion of PML as well as their type have been checked. MEDLINE has been searched for the most relevant publications about PML anatomy. Results Observation of normal specimens has confirmed the presence of three types of chordae tendineae: marginal, intermediate and basal, but between the last two, there is some of alternative nature. In degenerative mitral valve disease, the rough part is only 13% greater than the smooth one. In collagen degeneration, both parts contribute in more or less equal proportion to the dimensional increase of the middle scallop, so that the ratio between rough and smooth surface is maintained as in normal specimens. Conclusion This study reorganizes the previously proposed terminology of PML chordae tendineae. The research identifies the complemental and alternative presence of 'strut' and 'basal' chordae of PML, and it specifies the dimensions of the different anatomical components of the leaflet, in particular of the intermediate scallop. The observations give an accurate anatomical reference for the space of mitral reconstruction with minimal functional impact. J Cardiovasc Med 11:820-826 (C) 2010 Italian Federation of Cardiology.