Significant material property differences between the porcine ascending aorta and aortic sinuses

Area of Science:

• Biomechanical Engineering
• Cardiovascular Research
• Materials Science

Background:

• Valve-sparing aortic root replacement is used for sinus of Valsalva aneurysms.
• Previous finite-element models assumed uniform material properties for the aorta, neglecting differences between the ascending aorta and sinuses.
• This study aimed to compare the material properties of porcine ascending aorta and aortic sinuses.

Purpose of the Study:

• To compare the material properties of the ascending aorta and aortic sinuses.
• To inform more accurate finite-element models for aortic root repair.

Main Methods:

• Equibiaxial mechanical stretch testing was performed on porcine ascending aorta and aortic sinus specimens.
• Specimens were oriented longitudinally and circumferentially.
• Stress-strain data were fitted to Fung and Hookean models, and stiffness was compared at 0.35 Green strain.

Main Results:

• The ascending aorta exhibited a linear stress-strain response, while aortic sinuses showed a non-linear response.
• Both regions were stiffer circumferentially than longitudinally.
• The ascending aorta was significantly more compliant (less stiff) than the aortic sinuses in both directions.

Conclusions:

• Aortic sinuses are significantly stiffer than the ascending aorta, with both regions displaying anisotropy.
• Finite-element models of the aortic root require incorporation of these distinct material properties.
• Accurate material property differentiation is crucial for improving valve-sparing aortic root replacement techniques.