Hemodynamic impacts of hematocrit level by two-way coupled FSI in the left coronary bifurcation

Area of Science:

• Cardiovascular hemodynamics
• Biomedical fluid dynamics
• Computational biology

Background:

• Cardiovascular diseases are influenced by multiple factors, necessitating research into blood vessel flow dynamics.
• Blood circulation, particularly red blood cell (RBC) behavior, is strongly affected by oscillations.
• Understanding these effects is crucial for diagnosing and treating vascular conditions.

Purpose of the Study:

• To investigate the effects of oscillation on hemodynamic parameters within an elastic coronary artery bifurcation.
• To analyze blood flow using the Casson model with varying hematocrits in both elastic and rigid walls.
• To evaluate the role of the oscillatory shear index (OSI) in assessing arterial stenosis.

Main Methods:

• A 3D model of non-Newtonian, pulsatile blood flow in a left coronary artery bifurcation was simulated.
• The Casson model was applied with different hematocrit levels and analyzed for elastic and rigid walls.
• A two-way fluid-structure interaction (FSI) coupling method using an arbitrary Lagrangian-Eulerian approach was employed.

Main Results:

• Significant velocity differences were observed in the bifurcation at 30% hematocrit and 6.59E-04 Pa yield stress.
• Increased shear rates led to backflow and vortex flow in the LCx branch.
• Plaque generation was likely at the LM branch's end for 10% and 20% hematocrits; normal WSS was seen at 60% hematocrit.
• Shear stress was highest at the LM branch end in rigid vs. elastic models.
• OSI values peaked at the bifurcation and then rapidly decreased.

Conclusions:

• Hemodynamic parameters, including velocity and shear stress, are significantly altered by oscillation and hematocrit levels in coronary artery bifurcations.
• The study highlights the potential for plaque formation under specific hematocrit conditions and the importance of considering wall elasticity.
• OSI serves as a valuable indicator of flow dynamics, particularly at arterial bifurcations, complementing traditional WSS measurements.