Biomechanical characterization of the native porcine aortic root.

A thorough understanding of the well-functioning, native aortic root is pivotal in an era, where valve sparing surgical techniques are developed and used with increasing frequency. The objective of this study was to characterize the local structural stiffness of the native aortic root, to create a baseline for understanding how different surgical interventions affect the dynamics of the aortic root. In this acute porcine study (N = 10), two dedicated force transducers were implanted to quantify the forces acting on both the annular plane and on the sinotubular junction (STJ). To assess the changes in geometry, eleven sonomicrometry crystals were implanted within the aortic root. The combination of force and length measurements yields the radial structural stiffness for each segment of the aortic root. The least compliant segment at the annular plane was the right-left interleaflet triangle with a stiffness modulus of 1.1 N mm-1 (SD0.4). At the sinotubular junction the same segment (right-left) was most compliant, compared with the two other segments, however not statistically significant different. The elastic energy storage was derived from the aortic root pressure volume relationship; the mean elastic energy storage was 826 µJ (SD529). In conclusion, the aortic root has been characterized in terms of both segmental forces, segmental change in length and elastic energy storage. This study is the first to assess the radial structural stiffness of different segments of the aortic root. The presented data is reference for further studies regarding the impact of surgical interventions on the aortic root.