Morphology of the Human Mitral Valve II. The Valve Leaflets

Fifty normal mitral valves from adults were studied. Commissures, identified by commissural chordae tendineae and the tips of papillary muscles, partition the mitral valvular tissue into anterior and posterior leaflets. This definition incorporates into the posterior leaflet the structures formerly regarded as accessory leaflets. The posterior leaflet is further divided into scallops by clefts in its tissue. Cleft chordae provide a guide to these interscallop indentations or clefts. Partitioned this way, the posterior leaflet was tri-scalloped in 46 hearts. In 42, a large middle scallop was present with two smaller scallops on either side. Rough and clear zones can be defined on the anterior leaflet and rough, clear, and basal zones on the posterior leaflet. Additional Indexing Words: Commissure Prolapsed mitral valve Chordae tendineae Mitral regurgitation ALTHOUGH the anatomy of the human mitral valve has been studied closely, the description of the valve varies from textbook to textbookl-8 and from paper to paper.9-'5 For example, there is controversy as to the definition of commissural areas9 ' 11 and argu-ment as to the number of leaflets.1- ' In view of this lack of agreement, we have reinvesti-gated the anatomy of 50 human mitral valve leaflets. Methods The mitral valves of 50 hearts obtained at autopsy were studied. The hearts were selected from patients who had no clinical indication of mitral valve disease and at autopsy the valve looked normal. There were 26 males and 2