Dynamic indentation and microstructural analysis of artery under pre-strain in different directions

Abstract

Strain from mechanical overload is a critical factor in vascular wall rupture associated with vascular diseases. Therefore, investigating the mechanical properties of blood vessels under strain is essential. Previous studies have predominantly focused on strain-free tests, and lacking microstructural analysis under load conditions. In this study, a self-made indentation device was used to combine with a pre-strain apparatus. Dynamic indentation tests were conducted on porcine arteries under pre-strain. Hematoxylin & Eosin staining and Masson staining were employed to observe microstructural changes in the arteries under strain. The results indicate that under pre-strain, the shear modulus of the arteries is positively correlated with the strain ratio. Radial strain increase the arterial relaxation ratio, while axial strain decrease it. Pre-strain enhance the arterial storage and loss modulus, which peaks at resonance frequencies of approximately 0.04 Hz and 1 Hz. Under pre-strain, elastic fibers experience a decrease in axial diameter and a reduction in spacing. The distribution of collagen is abnormal under radial strain. In the design of artery stents, a rationally designed stent structure should be considered so that the localized strain of the vessel wall is more decomposed into the axial direction.