Pulmonary vascular disease in children with truncus arteriosus.

Pulmonary vascular structure was analyzed using quantitative morphometric techniques in lung biopsy (n = 17) and/or postmortem specimens (n = 18) from 23 patients aged 18 days to 13 years, with truncus arteriosus (TA) type I or II. All 14 patients younger than age 1 year, showed abnormal extension of muscle and an increase in pulmonary arterial medial thickness (p less than 0.01 in 18 of 24 biopsy and autopsy specimens), whereas 6 showed intimal proliferation. Structural abnormalities were usually potentially reversible, even in 5 infants with a pulmonary arteriolar resistance of greater than or equal to 8 units X m2. Abnormalities were more severe in 9 patients aged 3.5 to 13 years, 6 with medial atrophy and 4 with pulmonary arteriolar resistance of greater than 8 units X m2 that also showed intimal fibrosis, with or without plexiform lesions or hyalinized arteries. Findings indicate that biopsy specimens are helpful in assessing the severity of pulmonary vascular disease, and are representative of the entire pulmonary vascular bed (avoiding the lingula); however, interpretation can be difficult if a biopsy specimen is taken of only the peripheral intraacinar arteries, distal to the most damaged vessels. An intracardiac repair is recommended by 6 months, at which time severe pulmonary arterial medial hypertrophy and intimal proliferation can be expected to prejudice the repair.