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Updated: Aug 13, 2026
A Pipeline to Characterize Structural Heart Defects in the Fetal Mouse
Published on: December 16, 2022
Ultrastructural findings in lung biopsy material from children with congenital heart defects
Insights
Congenital heart defects in children cause abnormal pulmonary artery muscle growth and cellular changes. These findings in pulmonary arteries offer new insights into pediatric cardiovascular disease.
Area of Science:
- Cardiovascular Pathology
- Pediatric Cardiology
- Pulmonary Hypertension Research
Background:
- Congenital heart defects (CHDs) can lead to pulmonary hypertension, affecting pulmonary artery structure.
- Previous research has primarily focused on rat models for understanding these changes.
Purpose of the Study:
- To investigate the ultrastructural changes in pulmonary arteries of children with CHDs.
- To identify novel cellular components and alterations in the non-muscular regions of human pulmonary arteries.
Main Methods:
- Analysis of lung biopsy material from 6 children with congenital heart defects.
- Ultrastructural examination using electron microscopy.
- Comparison of findings with known changes in hypoxia-induced pulmonary hypertension models.
Main Results:
- All children exhibited right ventricular hypertrophy and most had increased pulmonary artery pressure.
- Presence of smooth muscle in smaller, more peripheral arteries than expected was observed in all cases.
- Pericytes and intermediate cells, previously identified as precursor smooth-muscle cells, were found in non-muscular arterial wall regions, alongside newly formed arterial muscle.
- Increased medial thickness in muscular arteries was associated with smooth muscle hypertrophy and increased extracellular connective tissue.
- Nerve axons and varicosities were ultrastructurally identified in the adventitia of small intra-acinar muscular arteries in 2 cases.
Conclusions:
- Children with CHDs show significant, previously undocumented ultrastructural changes in pulmonary arteries, including ectopic smooth muscle and novel cell types in non-muscular regions.
- These findings in pediatric pulmonary arteries resemble those seen in experimental pulmonary hypertension, suggesting shared pathomechanisms.
- The identification of nerve axons in the adventitia of small pulmonary arteries represents a novel ultrastructural observation in the human lung.
Abstract:
The ultrastructural features of pulmonary arteries are described in lung biopsy material from 6 children with congenital heart defects. Right ventricular hypertrophy was found in all 6 children and increased pulmonary artery pressure in all but one. The presence of muscle in smaller and more peripheral arteries than expected for the age of the child was detected in all cases. Ultrastructural examination of the peripheral arteries revealed, for the first time, in the nonmuscular regions of human arterial walls, pericytes and intermediate cells (previously shown to be precursor smooth-muscle cells); in addition, new arterial muscle was found in the normally nonmuscular region. In the 4 cases where medial thickness of the normally muscular arteries was increased, the smooth-muscle cells were hypertrophied and the extracellular connective tissue increased. In all cases, junctions between endothelial cells and smooth-muscle cells, intermediate cells, or pericytes were found. These changes are similar to those described in the rat with hypoxia-induced pulmonary hypertension. In addition, in 2 of the 6 cases, bundles of nerve axons in Schwann cell sheaths were found in adventitial layer of small, intraacinar muscular arteries (not previously demonstrated ultrastructurally at this site in the human lung); varicosities with agranular and granular vesicles, probably adrenergic, were also identified.
