Computational and experimental modeling of a univentricular circulation with systemic-topulmonary shunt and aortic coarctation.

Circulation in a univentricular physiology, palliated with a systemic-to-pulmonary shunt, is highly dependent on the hemodynamic behavior of the shunt and presence of an aortic coarctation (AC). Both local (shunt and AC) and peripheral (pulmonary and systemic, arranged in parallel) impedances need to be properly described to evaluate this unique circulation. One approach is based on in-vitro experiments, testing a threedimensional (3D) phantom in a mock circulatory system. Similarly, this may be achieved in-silico, coupling a 3D model to a lumped parameter network (LPN), requiring substantial computational cost. In this study the results obtained by applying the two methodologies are compared, enabling a mutual validation when matching each other, and using their differences to better understand single-ventricle hemodynamics. A patient-specific aortic arch model with AC and proximal shunt anastomosis was inserted into a mock loop with several resistive and compliant elements representing the downstream circulation. Pressures and flows were measured during pulsatile flow. A computational analogue was developed, coupling a 3D model to a LPN, and a pulsatile simulation with the same boundary conditions as in-vitro was performed. Comparison of the experimentally measured hemodynamic variables with those calculated in-silico suggested that typical in-vitro resistive components should be modeled as non-linear terms, although they do not reproduce the linear behavior of peripheral vascular resistances in-vivo. Moreover, pipe connections are likely to give a non-negligible contribution to the resistances downstream the 3D phantom. Computational modeling of complex hemodynamics is an important tool that can improve the understanding of invitro experiments. At the same time, validating the computational model against experimental data can result in a more flexible tool for further investigating complex hemodynamics