Background: Differences in the mechanical properties of aortic tissues and replacement materials can have unwanted hemodynamic effects leading to graft failure. The aim of this experimental study was to compare the mechanical properties of different graft-patch materials used in aortic arch reconstruction with those of healthy and dilated human ascending aortas (AAs).
Methods: Four square samples were taken from 30 healthy (n = 120) and 14 dilated (n = 56) AA rings and from 34 human pericardial sections (fresh [n = 68] and Carpentiers solution fixed [n = 68]). In addition, square samples from commercial bovine pericardium (n = 14) were also compared with woven Dacron grafts (n = 24) and tested biaxially. Stress-strain curves (0% to 30%) were generated using a biaxial tensile tester to quantify the anisotropic properties and stiffness of the materials at 37 degrees C.
Results: We found significant differences in stiffness and anisotropy among all material types. Fresh and fixed human pericardia, bovine pericardium, and Dacron were 9.5, 7.1, 16.4, and 18.4 times stiffer than dilated AAs, which was 1.3 times stiffer than healthy AAs under physiologic stretch. Only dilated and healthy AAs showed an increase in anisotropic properties with increasing strain.
Conclusions: The significant differences in the mechanical properties among all materials we found are intended to increase the awareness of these differences in materials used in aortic reconstruction surgery. This finding suggests that improvements are needed in prosthetic material design to better mimic native tissue.