Mechanical Properties of Tube-Shaped Poly (Vinyl Alcohol) Hydrogel Blood Vessel Biomodel

Biomodels, which mimic the shape and motion of blood vessels, have been developed for clinical training in endovascular intervention and for the technical development of interventional devices such as stents. The present authors have developed a biomodel made of poly (vinyl alcohol) hydrogel (PVA-H), which has good transparency, low surface friction, and dynamic viscoelasticity similar to that of arteries. However, evaluation of its behavior as an arterial biomodel has not been carried out. In order to develop a PVA-H biomodel which can accurately mimic the motion of blood vessels, it is necessary to measure and match its mechanical properties in a tube shape mimicking blood vessels. In this study, tube-shaped PVA-H biomodels were prepared, and their mechanical properties were evaluated as to pulse wave velocity (PWV), compliance, and transfer function. PWV was calculated with Young’s modulus and dimensions of the biomodels. A tube-shaped PVA-H model and a model made of commercial silicone were set in a pulsatile flow path apparatus filled pure water (23°C). Sinusoidal pulsatile waves of various frequencies generated by a screw pump were released into flow path. The flow rate, the inner pressure, and the diameter of the biomodels were measured. The compliance of a biomodel was calculated with changing pressures and diameters. The transfer function was obtained as the ratio of the amplitude of the pressure in front of a biomodel and that behind it. The two kinds of biomodels studied showed PWV similar to that of real arteries: PVA-H shows lower PWV which younger arteries tend to show, while silicone shows higher PWV, similar to the case of aged arteries. In compliance, PVA-H shows a value similar to that of arteries in the lower pressure range, whereas silicone shows a value similar to that of arteries at higher pressure. A difference of transfer function in relation to the pulsatile frequencies was observed. This phenomenon is similar to that of real blood vessels and explainable in terms of the theory of the forced vibration in single-degree-of-freedom systems with attenuation. The transfer function is affected by mechanical properties of the wall, and the difference between biomodels is due to the viscoelasticity of the biomodels. With PVA-H, these parameters can be gradually changed by adjusting factors such as concentration. These findings indicate that PVA-H would be useful for the development of biomodels.