Influence of Stretch Ratio on the Measurement of Arterial Stiffness Using Indentation¹

Indentation testing is efficient means for inspecting the inherent heterogeneity of arterial tissue under multiaxial loadings [1,2]. However, the majority of existing tests has been conducted on excised tissue under a relaxed condition, i.e., stretch ratio of 1. Studies on the effect of stretching on local material properties of arterial tissue are scarce. It has been demonstrated through an inflation testing method that the Young's modulus of arterial tissue increased significantly with a larger stretch ratio [3]. We hypothesized here that stretching also led to increased local stiffness of the artery. In this work, a stretching apparatus was designed to accommodate indentation tests under various stretch ratio conditions. Modulus of elasticity was calculated for both rubber and porcine carotid artery specimens.