Left Ventricular Trabeculations Decrease the Wall Shear Stress and Increase the Intra-Ventricular Pressure Drop in...

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Computational Fluid Dynamics

Background:

• Left ventricular (LV) geometry significantly influences intraventricular blood flow dynamics.
• Trabeculae and papillary muscles (PMs) are complex endocardial structures whose hemodynamic impact is not fully understood.
• Accurate modeling of these structures is crucial for understanding cardiac function and disease.

Purpose of the Study:

• To characterize the hemodynamics of detailed left ventricular (LV) geometries.
• To examine the impact of trabeculae and papillary muscles (PMs) on blood flow using high-performance computing (HPC).
• To propose a method for incorporating the effects of trabeculations into smoothed LV models.

Main Methods:

• Reconstruction of five pairs of detailed and smoothed LV endocardium models from high-resolution MRI of ex-vivo human hearts.
• Computational fluid dynamics (CFD) simulations with rigid walls and constant/transient flow inputs.
• Quantification of pressure drop, wall shear stress (WSS), and analysis of coherent structures using the Q-criterion.

Main Results:

• Trabeculae and PMs increase intra-ventricular pressure drop and reduce WSS.
• Endocardial structures disrupt the dominant vortex in smoothed models, creating secondary vortices.
• A porous layer (1.2·10⁻² m thickness, 20 kg/m² porosity) on smoothed models approximates detailed model hemodynamics.

Conclusions:

• Trabeculae and PMs significantly alter LV hemodynamics, affecting pressure gradients and flow patterns.
• The proposed porous layer method offers a computationally efficient way to represent trabeculation effects in simplified LV models.
• This approach can improve the accuracy of simulations for understanding cardiac blood flow in health and disease.