1. Nine patients with primary pulmonary vascular obstruction observed at the Children's Hospital Medical Center between 1953 and 1963 are presented.
2. The clinical profile is quite uniform and corresponds well with the 26 pediatric patients reported in the literature. Symptoms begin predominately under 3 years of age and consist principally of consequences of low cardiac output, including fatigue, dyspnea on exertion, and syncope. Signs are those of pulmonary artery hypertension leading to right-sided congestive failure. Death, often instantaneous, occurs usually within 1 year after onset of symptoms.
3. Findings at cardiac catheterization consist of pulmonary artery hypertension (exceeding systemic pressures), low cardiac output, pulmonary vascular obstruction, and a normal pulmonary capillary mean pressure. There are no left to right shunts present; a small right to left shunt at the atrial level (patent foramen ovale at autopsy was seen once.
4. Etiologic clues were not discovered. Detailed family histories are compatible with the possibility of a recessive trait. Familial incidence is reported.
5. No effective therapy is available.