In utero progressive pulmonary stenosis successfully treated with transcatheter intervention after delivery.

It is unclear whether pulmonary stenosis with intact ventricular septum is a secondary cardiac malformation. We report an infant with pulmonary stenosis (diagnosed by fetal echocardiography) with progressive obstruction in late gestation who presented with increasing transvalvular pressure gradients (15 mm Hg at 22 weeks' gestation to 47 mm Hg at 35 weeks). The tricuspid/mitral valve annulus ratio decreased from 1.25 at 24 weeks' gestation to 0.96 at 33 weeks. At 38 weeks' gestation, a male infant weighing 3,524 g, with Apgar scores of 9 and 9 at 1 and 5 minutes, respectively, was delivered by cesarean section. Critical pulmonary stenosis was confirmed by postnatal catheterization. These findings support the postulation that pulmonary stenosis is a progressive disorder. After percutaneous balloon dilatation, the transvalvular pressure gradient decreased and the right ventricular cavity increased gradually. The transvalvular pressure gradient had decreased to 15 mm Hg and the tricuspid/mitral valve annulus ratio was 0.93 at the age of 2 years.