Left atrial ligation alters intracardiac flow patterns and the biomechanical landscape in the chick embryo

Area of Science:

• Developmental Biology
• Cardiovascular Physiology
• Biomedical Engineering

Background:

• Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect leading to single ventricle physiology and high mortality.
• Intracardiac blood flow patterns during cardiac morphogenesis are implicated as a significant etiological factor in HLHS.
• The left atrial ligation (LAL) model in chick embryos provides a platform to study early hemodynamic changes in HLHS development.

Purpose of the Study:

• To test the hypothesis that LAL immediately alters intracardiac flow streams and the biomechanical environment.
• To investigate if these alterations precede the morphologic and structural defects observed in HLHS.

Main Methods:

• Utilized fluorescent dye injections in chick embryos to visualize and analyze intracardiac flow patterns following LAL.
• Quantified changes in the position of major venous flow streams.
• Developed an in silico computational model to simulate LAL and assess wall shear stress (WSS) distribution.

Main Results:

• Intracardiac flow patterns from the cardinal and vitelline veins were immediately altered post-LAL.
• A significant ventral shift in the flow streams of the right common cardinal and right vitelline veins was observed.
• In silico modeling revealed reduced WSS at the left atrioventricular canal and the left side of the common ventricle.

Conclusions:

• Immediate changes in intracardiac flow patterns post-LAL support the critical role of hemodynamics in HLHS progression.
• Reduced WSS at specific cardiac regions, identified by modeling, correlate with commonly affected areas in HLHS.
• These hemodynamic and biomechanical alterations likely contribute to abnormal growth and remodeling of left heart structures in HLHS.