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The pulmonary circulation in congenital heart disease. II. Pulmonary hypertension
Insights
Congenital heart disease in children causes pulmonary hypertension, leading to rapid, underestimated structural changes in pulmonary arteries. These changes stem from postnatal responses, not fetal persistence, impacting lung development.
Area of Science:
- Pediatric Cardiology
- Pulmonary Hypertension
- Congenital Heart Disease
Background:
- Abnormal hemodynamics in congenital heart disease affect developing pulmonary circulation in young children.
- Pulmonary hypertension in newborns leads to rapid structural changes, with underestimated speed of muscularity increase.
- Previously, the rapid postnatal development of pulmonary artery muscularity in response to hypertension was underestimated.
Purpose of the Study:
- To investigate the structural changes in the pulmonary circulation of infants and young children with congenital heart disease and pulmonary hypertension.
- To determine if pulmonary hypertension interferes with the growth and development of the pulmonary circulation.
- To explore the potential for quantitating peripheral pulmonary circulation development in lung biopsies.
Main Methods:
- Analysis of lung biopsies from infants and young children with congenital heart disease.
- Assessment of pulmonary artery structure, including wall thickness, muscularity, and arterial multiplication.
- Correlation of structural findings with hemodynamic conditions like pulmonary hypertension and elevated pulmonary vascular resistance.
Main Results:
- Thick-walled small arteries in infants with congenital heart disease and pulmonary hypertension result from rapid postnatal responses, not fetal persistence.
- In older patients (3 months-4 years) with ventricular septal defect, pulmonary hypertension hinders pulmonary circulation development, causing reduced size and multiplication of intra-acinar arteries.
- Elevated pulmonary vascular resistance is linked to impaired intra-acinar pulmonary circulation development, not obliterative vascular disease.
Conclusions:
- The rapid postnatal development of pulmonary artery muscularity in response to hypertension is significant and previously underestimated.
- Pulmonary hypertension adversely affects pulmonary circulation growth and development in children with congenital heart disease.
- Quantifying peripheral pulmonary circulation development via lung biopsies is feasible, enabling structure-function correlation before obliterative changes occur.
Abstract:
In young children with congenital heart disease the pulmonary circulation is exposed to abnormal haemodynamic conditions before it is fully developed. In the newborn infant the persistence or development of pulmonary hypertension rapidly leads to structural change. The speed with which an increase in muscularity can develop has hitherto been underestimated. In most children dying in early infancy with congenital heart disease and pulmonary hypertension the presence of thick walled small arteries is due not to persistence of the high wall thickness of foetal life, but to a rapid postnatal response of the pulmonary circulation to pulmonary hypertension. In older patients with a ventricular septal defect, aged between 3 months and 4 years, the presence of pulmonary hypertension has been shown to interfere with the growth and development of the pulmonary circulation, judging this by reduction in size and multiplication of intra-acinar arteries and an increase in muscularity of both pre and intra-acinar arteries and veins. In these patients elevation of pulmonary vascular resistance was associated with failure of the intra-acinar pulmonary circulation to develop normally and not with obliterative pulmonary vascular disease. Recent studies indicate that growth and development of the peripheral pulmonary circulation can be quantitated in lung biopsies taken from infants and young children with congenital heart disease. It should therefore be possibe to correlate structure and function at a critical period of lung development, before the changes of obliterative pulmonary vascular disease are established.