Myocardial dysgenesis with persistent sinusoids in a neonate with Noonan's phenotype.

Structural cardiac anomalies indicative of primary myocardial maldevelopment are reported in a newborn girl with congenital heart block. The cardiac findings included disordered trabeculation of both ventricles with persistent intramyocardial sinusoids, hypoplastic papillary muscles, and dysplastic atrioventricular valves with partial downward displacement of the septal leaflet of the tricuspid valve. Dilatation of the ascending aorta and craniofacial dysmorphism including webbed neck, hypertelorism, and low-set ears raise the possibility of Noonan syndrome.