Differentiation of functional and structural pulmonary atresia: Role of aortography

Among certain critically ill neonates with severe tricuspid regurgitation, including those with Ebstein's anomaly of the tricuspid valve, tricuspid valve dysplasia, transient tricuspid regurgitation of the newborn, Uhl's anomaly and hypoplasia of the right ventricle, selective right ventriculography may not distinguish between patients with associated functional and those with structural pulmonary atresia. In patients with a normal pulmonary valve and infundibulum, functional obstruction (nonvisualization of the pulmonary artery on right ventricular angiography when the pulmonary valve is anatomically patent and nonobstructive) results from a combination of massive tricuspid insufficiency and increased perinatal pulmonary vascular resistance. This differentiation between functional and structural pulmonary atresia is essential because of the therapeutic implications.In 33 neonates studied at cardiac catheterization from January 1974 through October 1977 standard hemodynamic measurements and right ventriculograms could not distinguish between functional and structural pulmonary atresia. Retrograde aortography, in the presence of a patent ductus arteriosus, provided excellent visualization of the pulmonary root and valve in these cases and, without exception, pulmonary regurgitation across the valve was observed in the patients with functional pulmonary atresia. Usually, the amount of regurgitated contrast material was dense and both the right ventricle and the right atrium were opacified. In addition, among the patients with functional pulmonary atresia, the pulmonary root and valve appeared wider and more patulous than in the patients with structural pulmonary atresia and normal or mildly increased right ventricular pressure was appreciated.