Heart valves demonstrate a characteristic stress-strain curve with a low slope portion, in which collagen fibers uncrimp, and a high slope region, in which the uncrimped collagen fibers bear load. The acuteness of the transition between these two regions depends upon collagen fiber alignment. We assessed the radius of transition curvature (RoTC) as an indicator of differences in collagen fiber alignment of porcine aortic and mitral valves (AV, MV, n=46 hearts) with age (6 weeks, 6 months, 6 years) in both the radial and circumferential directions. The RoTC of radial strips was 3-5 times greater than that of circumferential strips. Radially, RoTC was greater in the AV than in MV. Circumferentially, RoTC was lowest in the center of the MV anterior leaflet (MVAC), followed by AV, and then the free edge of the MV anterior leaflet. RoTC decreased with age, particularly in AV radial strips, likely due to age-related increases in collagen alignment and crosslinking. These findings are consistent with circumferentially oriented collagen fibers within valves, especially the high collagen fiber alignment in the MVAC. In conclusion, RoTC is an easily calculated parameter that may be useful in characterizing the orientation of fibers and the matrix composition of biological materials.
|Title of host publication||Proceedings of the 2009 SEM Annual Conference and Exposition on Experimental and Applied Mechanics, 1-4 June 2009, Albuquerque, New Mexico, USA|
|Place of Publication||Bethel, U.S.A.|
|Publisher||Society for Experimental Mechanics|
|Publication status||Published - 2009|