Static and Dynamic Compliance of Thick-Walled Vessel Models: Mathematical Modeling and Experimental Validation Using...

Thick-walled vascular models, including block models, are increasingly used for in vitro investigations of fluid dynamics and endovascular device testing, particularly fatigue testing at high frequencies, as valuable alternatives to thin-walled models due to their simpler fabrication. Physiologically compliant models provide more realistic insights into hemodynamics and implant deformation; however, no compact and experimentally validated closed-form equation exists to predict the volumetric compliance of thick-walled vessel models.

A closed-form mathematical equation was derived to estimate the volumetric compliance of thick-walled cylindrical vessel models. The equation was experimentally validated through static compliance tests on cylindrical vascular models of varying wall thicknesses fabricated from two silicone elastomers and polyvinyl alcohol hydrogel (PVA-H) with four PVA concentrations (10, 12, 14, and 16 wt/vol.%). Dynamic compliance tests were performed at 1, 5, 10, and 30 Hz to assess the viscoelastic behavior of the materials. Finally, an applicability study was performed by fabricating block-form anatomical aneurysm models targeting physiological volumetric compliance based on the predicted equation.

Predicted and measured values showed strong agreement (R² > 0.95). PVA-H-10 exhibited volumetric compliance within the physiological range (0.4-1.1%/mmHg). Volumetric compliance decreased by over 50% at 30 Hz, confirming viscoelastic behavior with a maximum loss to storage volumetric compliance ratio of 0.14. Measured aneurysm model compliance matched predictions with an error below 7%.

This study provided a validated mathematical and experimental framework for fabricating thick-walled vascular models with physiologically relevant volumetric compliance and viscoelasticity for fluid dynamics and endovascular device testing.