NOONAN SYNDROME - STRUCTURAL ABNORMALITIES OF THE MITRAL-VALVE CAUSING SUBAORTIC OBSTRUCTION

Among 41 consecutive children with classic Noonan syndrome, 27 patient s (66%) presented cardiac anomalies, Eight patients (19.5%) had a cong enital anomaly of the mitral valve consisting of 5 with partial atriov entricular canal defect and 3 with anomalous insertion of the mitral v alve on the ventricular septum. Five patients (12%) presented with a s ignificant left ventricular outflow tract obstruction caused by the an terior leaflet of the mitral valve: two cases with atrioventricular ca nal and three cases with isolated anomalous insertion of the mitral va lve. Echocardiography is the best tool for the diagnosis. Cardiac defe cts of patients with Noonan syndrome may be explained on the basis of anomalies of the extracellular matrix involving cardiac valves includi ng the mitral valve.