[Structural features of cardiomyocytes in the atrialized right ventricle in patients with Ebstein anomaly]

Area of Science:

• Cardiovascular Pathology
• Cardiac Ultrastructure
• Developmental Cardiology

Context:

• Ebstein anomaly is a congenital heart defect affecting the tricuspid valve.
• Understanding cardiomyocyte (CMC) morphology in the atrialized right ventricle (ARV) is crucial for characterizing the anomaly.
• Previous studies have not fully elucidated the ultrastructural differences in CMCs across different cardiac chambers in Ebstein anomaly.

Purpose:

• To compare the size and ultrastructure of cardiomyocytes in the ARV, right ventricle (RV), and right atrium (RA) of patients with Ebstein anomaly.
• To determine if ARV cardiomyocytes exhibit ventricular or atrial characteristics.
• To investigate age-related changes in CMC morphology within the context of Ebstein anomaly.

Summary:

• Cardiomyocyte size did not significantly differ between ARV, RV, and RA in patients under 10 years.
• In patients over 10 years, ARV and RV cardiomyocyte diameters were similar, but larger than RA cardiomyocytes.
• Ultrastructural analysis revealed T-system channels and intercalated disks more frequently in ARV and RV CMCs compared to RA.
• Abnormal myofibrils and nuclear displacement were observed in CMCs, with variations between ARV, RV, and RA.

Impact:

• The findings suggest that cardiomyocytes in the atrialized right ventricle retain ventricular-specific features.
• This preserves ventricular specificity, offering insights into the developmental and cellular basis of Ebstein anomaly.
• The study provides a detailed ultrastructural characterization of cardiomyocytes in affected regions, aiding in future research and potential therapeutic strategies.