Collagen content in normal, pressure, and pressure-volume overloaded developing human hearts

Area of Science:

• Cardiovascular Research
• Pediatric Cardiology
• Cardiac Pathology

Background:

• Myocardial collagen increases with pressure overload in adults, but this is poorly understood in infants.
• Congenital heart defects in infants can cause pressure or volume overload, affecting heart tissue composition.

Purpose of the Study:

• To compare myocardial collagen volume fraction in infants with normal hearts, isolated right ventricular pressure overload (tetralogy of Fallot), and combined volume/pressure overload (aortic valve atresia).
• To determine the distribution of collagen within the neonatal myocardium in these conditions.

Main Methods:

• Analysis of right ventricular biopsy specimens from cadaver hearts of normal infants, infants with tetralogy of Fallot (ToF), and infants with aortic valve atresia (AVA) at different ages.
• Masson's trichrome staining and point counting method to quantify the myocardial volume fraction of collagen.

Main Results:

• Myocardial collagen volume fraction was significantly higher in older infants with aortic valve atresia (AVA-I) (8.0%) compared to normal infants (3.3%), ToF infants (3.2%), and newborns with AVA (AVA-NB) (3.5%).
• A trend towards increased collagen was observed in the subendocardium, particularly in AVA-I patients.

Conclusions:

• Infants with severe aortic valve atresia (AVA-I) exhibit increased myocardial collagen compared to normal, ToF, and AVA-NB groups.
• The subendocardium shows the greatest increase in collagen in affected infants, suggesting a specific regional response to cardiac overload.