Lesions producing congenital mitral valvar stenosis are complex and often multiple, From 1970 to 1994, 58 patients under 12 years of age (mean 5 ± 3.2 y) underwent surgical treatment for such malformations in our department. In order to provide a clear understanding of the pathology, we used a classification based on anatomy and function. Echocardiography was a major tool of the preoperative investigations. The lesions were classified as follows:

Normal papillary muscles: commissural fusion in 19, excess leaflet tissue in 2, valvar ring in 12, and annular hypolasia in 2.

Abnormal papillary muscles: paachute arrangement in 10 and hammock mitral valve in 13.

Associated malformations were found in 63%, the most common being multiple stenosis in the left heart. Conservative treatment was possible in 54 patients (95%) using the techniques developed by Carpentier. Hospital mortality was 22%, with 95% confident limits between 13 and 36% (13/58). Of the 13 patients with a hammock valve, 6 died in hospital. The overall mean period of follow up was 7.8 + 5 years. No thromboembolic events occured after conservative surgery. Late death occured in 3%. The actuarial survival at 5 years was 64 + 15%. Reoperation was needed for residual mitral valvar stenosis in three patients or insufficiency in one.

In spite of effective techniques to relieve mitral obstruction, 12% of our patients need early or delayed replacement of the valve. The hospital mortality remains high due to the complexity of the lesions, associated with the associated malformations. Echocardiography proved to be extremly helpful for the functional analysis. In order to improve operative results, simple and early valvar repair, even if considered palliative, seems to be appropriate.