Between 1980 and 1993, 20 patients less than 1 year of age underwent operations for congenital mitral valve disease. Ten patients had congenital mitral incompetence and 10 had congenital mitral stenosis. Mean age was 6.6 +/- 3.4 months and mean weight was 5.6 +/- 1.5 kg. Atrioventricular canal defects, univentricular heart, class III/IV hypoplastic left heart syndrome, discordant atrioventricular and ventriculoarterial connections, and acquired mitral valve disease were excluded. Indications for operation were intractable heart failure or severe pulmonary hypertension, or both. Associated lesions, present in 90% of the patients, had been corrected by a previous operation in seven. In congenital mitral incompetence there was normal leaflet motion (n = 3), leaflet prolapse (n = 2), and restricted leaflet motion (n = 5). In congenital mitral stenosis anatomic abnormalities were parachute mitral valve (n = 4), typical mitral stenosis (n = 3), hammock mitral valve (n = 2), and supramitral ring (n = 1). Mitral valve repair was initially performed in 19 patients and valve replacement in one with hammock valve. Concurrent repair of associated lesions was performed in 12 patients. The operative mortality rate was zero. There were six early reoperations in five patients for mitral valve replacement (n = 4), a second repair (n = 1), and prosthetic valve thrombectomy (n = 1). One late death occurred 9 months after valve replacement. Late reoperations for mitral valve replacement (n = 2), aortic valve replacement (n = 1), mitral valve repair (n = 2), subaortic stenosis resection (n = 1), and second mitral valve replacement (n = 1) were performed in five patients. Actuarial freedom from reoperation is 58.0% +/- 11.3% (70% confidence limits 46.9% to 68.9%) at 7 years. After a mean follow-up of 67.6 +/- 42.8 months, 94% of living patients are in New York Heart Association class I. Doppler echocardiographic studies among the 13 patients with a native mitral valve show mitral incompetence of greater than moderate degree in one patient and no significant residual mitral stenosis. Overall, six patients have mitral prosthetic valves with a mean transprosthetic gradient of 6.2 +/- 3.7 mm Hg. These results show that surgical treatment for congenital mitral valve disease in the first year of life can be performed with low mortality. Valve repair is a realistic goal in about 70% of patients and possibly more with increased experience. Reoperation rate is still high and is related to complexity of mitral lesions and associated anomalies, but late functional results are encouraging.

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17 thymomas were studied by indirect immunofluorescence for the presence of thymic hormones and antigens of the major histocompatibility complex (MHC). The thymoma epithelial cells (specifically identified by their keratin content) contained thymic hormones (thymulin and thymosin al), a finding corroborated by the observation of elevated thymulin serum levels. In contrast with normal or hyperplastic thymuses, thymoma epithelial cells did not express HLA-DR and HLA-DC antigens as assessed by immunofluorescence as well as immunoblot analyses. Conversely, MHC class I antigens (HLA-ABC) were normally expressed. Thus, we conclude that thymoma epithelial cells are endocrinologically active but are defective for the expression of some MHC products (class II molecules) known to play an essential role in intrathymic T cell differentiation.