Porcine aortic wall flexibility. Fresh vs Denacol fixed vs glutaraldehyde fixed

Area of Science:

• Biomaterials Science
• Cardiovascular Engineering
• Tissue Engineering

Background:

• Stentless bioprosthetic heart valves are theorized to offer superior hemodynamics and durability compared to stented valves.
• Glutaraldehyde is a common cross-linking agent for porcine bioprostheses, but concerns exist regarding calcification.
• Polyepoxy compounds, like Denacol, are explored as alternatives to mitigate bioprosthetic calcification.

Purpose of the Study:

• To evaluate the impact of different fixation methods on the flexibility of porcine aortic walls.
• To compare the mechanical properties of fresh, glutaraldehyde-fixed, and Denacol-fixed porcine aortic tissue.

Main Methods:

• Porcine aortic root ring specimens were prepared from three groups: fresh, low-pressure glutaraldehyde fixed, and low-pressure Denacol fixed.
• Tensile testing was performed by pulling ring specimens between two rods to record load-deformation relationships.
• Young's modulus was calculated from the load-deformation data to quantify tissue stiffness at low strains.

Main Results:

• Young's moduli were 0.113 ± 0.036 MPa (fresh), 0.494 ± 0.113 MPa (Denacol fixed), and 1.320 ± 0.292 MPa (glutaraldehyde fixed).
• Denacol-fixed aortic walls exhibited significantly greater flexibility (lower Young's modulus) than glutaraldehyde-fixed walls.
• Denacol fixation preserved residual strains, unlike glutaraldehyde fixation, which altered them.

Conclusions:

• Denacol fixation results in a more flexible porcine aortic wall compared to glutaraldehyde fixation.
• The Denacol fixation method better retains the natural mechanical properties, including residual strains, of the porcine aortic tissue.
• These findings suggest Denacol may be a favorable cross-linking agent for developing more durable and functional stentless bioprosthetic heart valves.