[HYPOPLASTIC LEFT HEART SYNDROME: MORPHOGENESIS OF PATOMORPHOLOGICAL TYPES OF THE LEFT VENTRICLE]

Area of Science:

• Developmental Biology
• Cardiovascular Pathology
• Embryology

Background:

• Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect.
• The morphogenesis of the left ventricle in HLHS is complex and not fully understood.
• Variations in left ventricular morphology are observed in HLHS patients.

Purpose of the Study:

• To investigate the morphogenesis of the left ventricle in hypoplastic left heart syndrome (HLHS).
• To identify and classify distinct morphological types of the hypoplastic left ventricle.
• To correlate specific developmental events with observed left ventricular morphologies in HLHS.

Main Methods:

• Analysis of pathomorphological types of the left ventricle in HLHS.
• Morphometric data analysis.
• Correlation of embryogenesis stages with myocardial and septal development.

Main Results:

• Five types of hypoplastic left ventricles were identified based on wall structure, cavity shape, and endocardial fibroelastosis.
• Leftward interventricular septum displacement (4-5 weeks gestation) is linked to atresia and a slit-like, hypoplastic LV wall.
• Conotruncus septum displacement results in a slit-like cavity and hypertrophied LV wall.
• Endocardial fibroelastosis patterns correlate with the timing of its appearance during myocardial embryogenesis (lacunar, lacunar-cylindrical, or cylindrical LV cavity shapes).

Conclusions:

• Left ventricular morphogenesis in HLHS is influenced by the timing and nature of septal displacement and the onset of endocardial fibroelastosis.
• Specific embryogenic events, such as interventricular septum positioning and myocardial compaction, dictate the resulting left ventricular morphology in HLHS.
• The identified pathomorphological types provide insights into the developmental pathways leading to HLHS variations.