Congenitally "Inverted" Pulmonary Valve in Tetralogy of Fallot: When Nature Falters.

A cyanotic neonate with tetralogy of Fallot was found to have a congenitally inverted pulmonary valve. Diagnosis was made via echocardiography and cardiac catheterization. The valve opened retrograde into the right ventricle, which allowed severe regurgitation and prevented anterograde flow. This report is the first description of this anomaly in medical literature. (Level of Difficulty: Intermediate.).