Lung pathology in infants with severe pulmonary hypertension and cardiac disease.

Lung biopsy specimens were taken from 39 infants younger than 12 months of age with congenital heart disease and severe pulmonary hypertension (Pp/Ps greater than or equal to 0.75) accompanied by respiratory distress. The pathological change in lung specimens and clinical courses were compared. These 39 infants underwent surgical treatment of patent ductus arteriosus (PDA), seven patients; ventricular septal defect (VSD), 13 patients; and complex heart anomaly, 19 patients. The common pathological findings of the lung specimens taken from these infants were lymphoid cellular infiltration and thickening of the alveolar septum, which we have called "septitis" in the present study. In most cases pulmonary vascular obstructive change was within Grade 2 of the Health-Edwards criteria. Septitis was classified into three categories: mild, moderate, and severe. Only three of the 19 infants with severe septitis survived postoperatively, whereas 10 of the 12 infants with moderate septitis and all eight with mild septitis could be successfully weaned. The cause of septitis remains unidentified. We have found the patient's age and pulmonary hypertension to be closely related to the grade of septitis in this study. Septitis plays a much more important role than pulmonary vascular obstructive change in the prognosis of pulmonary hypertensive heart disease in early infancy.