Lung hypoplasia in congenital pulmonary valve stenosis

The pulmonary function of ten adult patients with congenital pulmonary valvular stenosis was investigated. The patients clearly showed smaller lungs than healthy control subjects of equivalent age and height; lung elastic recoil pressure was normal at any given percentage of measured total lung capacity, indicating that postnatal parenchymal damage is not the cause of the small lungs. The lung diffusing capacity for carbon monoxide was reduced, reflecting the anatomical alterations of the pulmonary vascular bed. Finally, the maximal flow-static recoil curves showed a fixed (not dynamic) reduction of airway dimensions: the critical transmural pressure in the collapsible flow-limiting segment (Ptm') was normal, but the conductance of the S segment was lowered. These abnormalities most likely reflect inadequate development of the lung and suggest that pulmonary blood pressure may be an important determinant of lung growth in the postnatal period.