A Biomechanical and Biochemical Synergy Study of Heart Valve Tissue

The function of heart valves is to allow blood to flow through the heart smoothly and to prevent retrograde flow of blood. Previous studies have shown that the mechanical properties of heart valve tissues, microstructures of extracellular matrix, and collagen concentrations are the keys to the healthy heart valves and, therefore, are crucial to the development of viable tissue-engineered heart valve replacements. Therefore, this study investigates the relationship between these factors in native porcine aortic and pulmonary valves and provides insights to the healthy heart valves. Heart valve leaflets are prepared for biaxial stretching to obtain mechanical properties. The average collagen concentrations of heart valve leaflets are determined via an assay kit. The results indicate that aortic valves are stiffer than pulmonary valves macroscopically and stiffness varies more in the circumferential direction for the aortic valve than it does for the pulmonary valve. Microscopically, it is due to collagen fibers in aortic valves are more in alignment than ones in pulmonary valves, which are more randomly in direction. Collagen assay results show that collagen concentrations are higher in the edges of pulmonary valves than in aortic valves. The results also suggest the duration of extraction may have significant affects on the concentration results. This work provides quantified stress and strain environment within heart valve tissues to help further studies on how to treat heart valve disease and create more viable heart valve replacements.