Mitral valve repair: critical analysis of the anatomy discussed

Abstract

In this brief review, we discuss the anatomy of the mitral valve pertinent to surgical repair. First, we emphasise the need for diagnosticians to describe the valve in the context of the position of the heart within the body, following the standard rules of anatomy, and using attitudinally appropriate descriptions. It has become customary to describe cardiac structures as if the heart is positioned on its apex. This cannot be good in the current era, when the tomographic techniques increasingly used for diagnosis demonstrate the heart as seen in the body. We then discuss the overall valvar structure in terms of a complex made up of the annulus, the leaflets, their tendinous cords, and the supporting papillary muscles. After providing accounts of the salient structure of each part of the complex, we discuss potentially divisive issues, such as the number of leaflets, and the categorisation of the tendinous cords. We explain how most of the disagreements stem not from differences in observation, but rather from differences in definitions. We suggest that these can largely be dissipated if the valve is analysed in its closed, rather than its open, position. When seen in the closed position, it becomes obvious that the key feature is the solitary zone of apposition between the major components of the skirt of leaflet tissue, this being the major functional part of the valvar complex. Finally, we discuss the relationships of the valvar complex to the other cardiac structures, concentrating on the other cardiac valves, the conduction tissues, and the coronary arteries and veins.