Numerical simulation of mechanical mitral heart valve closure

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Cardiovascular Mechanics

Background:

• Mechanical heart valves are crucial implants, but their closing dynamics can induce significant fluid stresses.
• Understanding these stresses is vital for predicting valve performance and potential blood damage.
• Previous studies suggest increased blood damage during the closing phase of mechanical heart valves.

Purpose of the Study:

• To computationally simulate the closing dynamics of a mechanical heart valve in the mitral position.
• To delineate the fluid-induced stresses, specifically pressure and shear stress, during valve closure.
• To compare stress fields between normal valve closure and a simulated gravity-induced closure.

Main Methods:

• Utilized computational fluid dynamics (CFD) to model mitral heart valve closure.
• Performed three distinct numerical simulations: steady flow, gravity closure, and normal closure.
• Calculated pressure and wall shear stress fields in the clearance and inflow regions.

Main Results:

• Normal closure generated significant negative pressure transients and high wall shear stresses (approx. 4000 Pa).
• Gravity closure resulted in lower wall shear stresses (approx. 725 Pa) and lacked negative pressure transients.
• The simulated normal closure aligns with previous findings of increased blood damage during this phase.

Conclusions:

• The normal closure mechanism of mechanical mitral valves induces substantial negative pressure transients and elevated wall shear stresses.
• These findings support the hypothesis that normal closure dynamics contribute to blood damage.
• CFD simulations provide valuable insights into the biomechanical forces acting on mechanical heart valves.