Quantifying Regional and Age-Dependent Microstructural Changes in Porcine Ventricles from Neonatal to Adulthood Using...

Area of Science:

• Cardiovascular Research
• Biomedical Engineering
• Computational Biology

Background:

• The heart's microstructure changes significantly after birth and with aging due to physiological demands.
• Understanding these age-dependent and region-specific changes is crucial for developing accurate computational models of cardiac function.
• Existing models often lack detailed microstructural data, limiting their bio-fidelity.

Purpose of the Study:

• To investigate the three-dimensional microstructure of porcine ventricles across different age groups, from neonatal to adult.
• To quantify age- and region-specific changes in cardiomyocyte and collagen fibril organization.
• To provide essential data for the development of advanced constitutive models for cardiac simulations.

Main Methods:

• Utilized diffusion-tensor magnetic resonance imaging (DT-MRI) for fiber tractography and fractional anisotropy (FA) analysis.
• Employed two-photon excited fluorescence and second-harmonic generation microscopy to visualize and quantify cardiomyocyte and collagen fibril structures.
• Analyzed microstructure at four distinct time points from neonatal to adult porcine hearts.

Main Results:

• Left ventricles showed higher FA than right ventricles.
• Adult hearts exhibited lower FA compared to younger hearts.
• Anterior ventricles (both left and right) displayed greater cardiomyocyte and collagen fibril rotation and dispersion than posterior regions.
• Adult hearts had increased cardiomyocyte and collagen fibril rotation and dispersion compared to young hearts.
• Right ventricles showed greater cardiomyocyte rotation in young hearts, while adult left ventricles showed greater rotation.

Conclusions:

• Significant age- and region-dependent variations exist in porcine ventricular microstructure.
• The study provides critical quantitative data on cardiomyocyte and collagen organization across the lifespan.
• These findings are vital for enhancing the accuracy and bio-fidelity of computational models used in cardiovascular research and engineering.