Anatomical variations of the mitral leaflets: Unified and accessory scallops

To investigate the morphological variants of the leaflets and scallops of the mitral valve in fresh hearts of healthy individuals and to determine their morphometric values.

The hearts of 100 autopsy cases were analysed. The weight and dimensions of the heart and mitral valve circumference were measured. The morphology of the mitral leaflets and scallops and their hinge distances and heights were recorded.

In 64 cases, classical leaflet morphology (aortic leaflet, mural leaflet consisting of 3 scallops, superolateral and inferoseptal commissures) was observed. In 24 cases accessory scallops and in 12 cases unified scallops were identified. The mean hinge distance and height of accessory scallops were 8.69±2.5 mm, and 9.79±2.5 mm respectively, and these values were 45.73±9.8 mm, and 11.95±2.3 mm in unified scallops, respectively. Accessory and unified scallops can be found in any region of mural leaflet, but the vast majority (96 %) are associated with it and more than half (60 %) are located at the commissural ends. In 1 case aortic leaflet consisted of two scallops and mural leaflet had 3 scallops in 63 %, 4 scallops in 22 %, 2 scallops in 8 %, 1 scallop in 4 % and 5 scallops in 3 %.

Significant morphological variations between mitral leaflets and scallops have been reported. These variations may affect the placement of the suture or device in mitral valve repair. It was also concluded that these variations cannot be predicted by age, gender or cardiac morphometry.