The design of the normal aortic valve

Area of Science:

• Cardiovascular Biology
• Biomedical Engineering
• Medical Device Design

Background:

• The in vivo design parameters of the natural aortic valve remain largely unknown.
• This knowledge gap has led to varied designs in bioprosthetic aortic valves.

Purpose of the Study:

• To investigate the dynamic in vivo design parameters of the natural aortic valve during the cardiac cycle.
• To understand how aortic pressure and ventricular geometry influence aortic valve geometry.

Main Methods:

• Utilized radiopaque markers placed within the aortic valve to track leaflet movement in vivo.
• Analyzed marker trajectories to determine changes in valve geometry and design parameters throughout the cardiac cycle.

Main Results:

• Aortic valve design parameters continuously change with aortic pressure and ventricular geometry.
• During diastole, leaflet tilt and angle changes occur; during systole, the valve geometry shifts from conical to cylindrical.
• Specific mid-diastole parameters identified: Rb/Rc = 1.2, H/Rc = 1.4, leaflet free-edge angle (phi) = 34°, and bottom surface angle (alpha) = 20°.

Conclusions:

• The natural aortic valve exhibits dynamic geometric changes crucial for function.
• Understanding these in vivo parameters is essential for optimizing bioprosthetic valve design.
• Deviations from natural design parameters may compromise valve efficiency and longevity.