A comparative study on the mechanical properties of the umbilical vein and umbilical artery under uniaxial loading

Purpose: Coronary Artery Disease (CAD) is the main cause of mortalities worldwide. The Saphenous Vein (SV) and Umbilical Vein (UV) are the most common veins using for treatment as a Coronary Artery Bypass Graft (CABG). The mechanical properties of UV owing to its long-term patency for CABG are deemed important. However, there is a lack of knowledge on the mechanical properties of UV. In this study, the linear (Young's modulus and maximum stress) and nonlinear (hyperelastic material coefficients) mechanical properties of 8 human umbilical vein and umbilical artery (UA) are investigated using a series of uniaxial tensile tests. The nonlinear mechanical behavior of UV/UA is computationally investigated using hyperelastic strain energy density functions, including Mooney-Rivlin and Ogden. A hyperelastic constitutive model is selected to best fit the axial behavior of the UV/UA. Results: The results reveal that the Young's modulus and maximum stress of UA are 342% and 19% more than that of UV, respectively. The Mooney-Rivlin material model is selected to represent the nonlinear behavior of the UV and UA which can be used in future biomechanical simulations of the umbilical vein and umbilical artery. Conclusions: The higher mechanical properties of umbilical artery compared to umbilical vein might have related to the amount of elastin and collagen content on the UA wall. The results of this study could be utilized to understand the extension and rupture mechanism of UV and UA, and has implications for interventions and surgeries, including balloon-angioplasty, bypass, and stenting.