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Pulmonary vascular damage and the development of cor pulmonale following hyaline membrane disease
1Department of Paediatric Cardiology, Institute of Child Health, London, England.
Insights
Infants with chronic lung disease after hyaline membrane disease (HMD) show reduced alveoli and thickened pulmonary arteries, regardless of cor pulmonale (CP). Vascular changes persist even after recovery from HMD.
Area of Science:
- Pediatric Pathology
- Pulmonary Medicine
- Neonatology
Background:
- Hyaline membrane disease (HMD) is a common neonatal respiratory disorder.
- Chronic lung disease (CLD) can develop in infants following HMD.
- Pulmonary vascular remodeling is a known complication of neonatal lung injury.
Purpose of the Study:
- To investigate pulmonary vascular morphology in infants and young children with CLD following HMD.
- To determine the relationship between pulmonary vascular changes and the presence or absence of cor pulmonale (CP).
- To assess if vascular abnormalities correlate with the severity of lung disease or recovery status.
Main Methods:
- Light microscopic morphometric techniques were employed.
- Lungs from 17 infants and young children (2 weeks to 3.5 years) with CLD post-HMD were studied.
- Patients were categorized into three groups based on illness course and presence of CP.
Main Results:
- All groups exhibited reduced alveolar counts and increased bronchial smooth muscle in small airways.
- Pulmonary arterial medial thickness was significantly increased in all three groups (P < 0.001).
- Vascular changes ranged from persistence of fetal state to marked secondary muscularity, with extension into smaller arteries in some groups.
Conclusions:
- Infants recovering from HMD can have significant pulmonary vascular abnormalities even without cor pulmonale.
- The presence of cor pulmonale does not necessarily indicate advanced obliterative pulmonary vascular disease.
- Pulmonary vascular morphology does not consistently correlate with the presence or absence of cor pulmonale in this cohort.
Abstract:
Light microscopic morphometric techniques have been used to study the lungs in 17 infants and young children aged 2 weeks to 3.5 years who were born prematurely, developed hyaline membrane disease (HMD), and died with chronic lung disease. They were divided into three groups. In group 1 the babies died without recovering from their initial illness at age 2-13 weeks. In group 2 they died, aged 4-15 months, having recovered from the neonatal illness. Neither group showed clinical or pathological evidence of cor pulmonale (CP). In group 3 children died aged 6 months to 3.5 years with CP. None of the 17 patients had classical fibrotic bronchopulmonary dysplasia (BPD) but all had a reduced alveolar number and an increase in bronchial smooth muscle in small airways. All three groups showed an increase in pulmonary arterial medial thickness (P less than 0.001). In group 1 the appearance of the arteries suggested persistance of the fetal state. In group 2 and 3 the vessels had a more mature structure; in group 3 a marked secondary increase in muscularity was found, approaching the thickness seen in fetal life. In groups 2 and 3 muscle extended into smaller arteries than normal. Vein wall thickness was increased. The alveolar to arterial ratio was normal, the alveolar number was reduced, therefore the total number of arteries was reduced in all three groups. Thus, babies who recover from HMD may have significant vascular abnormalities in the absence of CP; conversely, CP if present, does not mean advanced obliterative pulmonary vascular disease. Thus, pulmonary vascular morphology does not correlate with the presence or absence of CP.