Myocardial changes in immature infants requiring prolonged ventilation

Area of Science:

• Neonatal Cardiology
• Pediatric Pathology
• Respiratory Medicine

Background:

• Premature infants requiring prolonged mechanical ventilation and high oxygen concentrations are at risk for cardiopulmonary complications.
• Bronchopulmonary dysplasia is a known complication, but associated cardiac pathology is less understood.
• Cardiac hypertrophy and myocardial lesions have been observed in infants with severe bronchopulmonary dysplasia.

Purpose of the Study:

• To investigate the nature and potential causes of cardiac lesions in infants with prolonged ventilation and high oxygen exposure.
• To compare findings in ventilated infants with a control group of stillbirths and neonatal deaths.
• To elucidate the relationship between respiratory support, hypoxia, and cardiac pathology in immature infants.

Main Methods:

• Necropsy examination of 14 infants with prolonged ventilation (≥14 days) and high oxygen concentrations.
• Histopathological analysis of cardiac tissue, including assessment of heart weight, valves, septum, and intramural vessels.
• Comparison with cardiac findings in 100 control infants (50 stillbirths, 50 neonatal deaths) of comparable gestational age.

Main Results:

• 11 out of 14 infants exhibited cardiac hypertrophy (heart weight >2 SD above mean), primarily in immature neonates with severe bronchopulmonary dysplasia.
• Cardiac hypertrophy involved ventricles and septum, showing necrosis and fibroelastotic scarring, with intimal thickening in intramural vessels.
• Intravascular and endocardial platelet thrombi were found in the youngest infants with hypertrophy; myocardial necrosis was present in 19/100 control infants.

Conclusions:

• Prolonged high-concentration oxygen ventilation in immature infants is associated with significant cardiac hypertrophy and myocardial damage.
• These cardiac lesions appear to be a consequence of ongoing hypoxia and coronary circulation compromise.
• Myocardial damage represents a serious potential complication, impacting therapeutic strategies for immature, asphyxiated infants.