Characterization of the highly nonlinear and anisotropic vascular tissues from experimental inflation data: a validation study towards the use of clinical data for in-vivo modeling and analysis

摘要

In this study, we investigate whether an inverse modeling approach can be used to characterize vascular tissue behavior from experimental data of blood vessels subjected at various levels of internal pressure and axial stretch that mimics clinical data. In-vivo condition of blood vessel with either constant or variable axial response is considered. To compensate for the limitation of this data that does not provide axial force information, a new concept to constrain the ratio of axial to circumferential elastic moduli to a typical range is proposed. Vessel wall constitutive behavior was modeled with a transversely isotropic hyperelastic equation that accounts for dispersed collagen fibers, and both single-layer and bi-layer models were implemented for examination. The possibility of obtaining the fiber orientation in this approach was also evaluated. The characterized behavior was validated with an independent pipette-aspiration biaxial data on the same samples. It was found that homogenous assumption is an over-simplification. The constrained bi-layer model was in excellent agreement with both types of experimental data. Fiber angle is needed to be pre-defined to avoid covariance problem. Finally, our approach is relatively invariant to any particular axial response. Therefore, we believe that inverse modeling approach is suitable for in-vivo characterization.