Surgical treatment of duplication of the mitral valve.

Two cases of duplication of the mitral valve were found at operation. One was associated with isolated mitral regurgitation (Case 1) and the other with the intermediate type of atrioventricular canal (Case 2). In Case 1, the fibrous band between the major orifice and accessory orifice was cut, and the anterior mitral valve was extended by glutaraldehyde-treated homopericardium after the cleft had been repaired. On the other hand, a small accessory orifice encountered in Case 2 was closed by direct sutures and the same method of mitral valve extension was employed for mitral valve reconstruction as in Case 1. Surgical correction of duplication of the mitral valve is mandatory depending on the associated cardiac malformation, the type and size of the defect, and the surgeon's experience.