Variations of the area and shape of the left atrioventricular valve and its cusps and leaflets.

Measurement of the areas of the cusps and leaflets of the left atrioventricular valve (LAV) and a study of their shape were performed in 91 normal human hearts, to assess the range of variation and determine the most frequent morphologic pattern. The average areas were as follows: LAV, 904.9 mm2; anterior cusp, 447 mm2; posterior cusp, 457 mm2; anterolateral leaflet, 118.6 mm2; intermediate leaflet, 212.7 mm2; and posteromedial leaflet, 126 mm2. The commonest shape of the leaflets of the posterior cusp, proved to be rectangular.