The impact of calcification patterns in transcatheter aortic valve performance: a fluid-structure interaction analysis.

Transcatheter aortic valve replacement (TAVR) strongly depends on the calcification patterns, which may lead to a malapposition of the stented valve and complication onsets in terms of structure kinematics and paravalvular leakage (PVL). From one anatomical-resembling model of the aortic root, six configurations with different calcific deposits were built. TAVR fluid-structure interaction simulations predicted different outcomes for the different calcifications patterns in terms of the final valve configuration in the implantation site and the PVL estimations. In particular models with deposits along the cups coaptation resulted in mild PVL, while those with deposits along the attachment line in moderate PVL.

Distributed and Lumped Parameter Models for the Characterization of High Throughput Bioreactors.

Next generation bioreactors are being developed to generate multiple human cell-based tissue analogs within the same fluidic system, to better recapitulate the complexity and interconnection of human physiology [1, 2]. The effective development of these devices requires a solid understanding of their interconnected fluidics, to predict the transport of nutrients and waste through the constructs and improve the design accordingly. In this work, we focus on a specific model of bioreactor, with multiple input/outputs, aimed at generating osteochondral constructs, i.e., a biphasic construct in which one side is cartilaginous in nature, while the other is osseous. We next develop a general computational approach to model the microfluidics of a multi-chamber, interconnected system that may be applied to human-on-chip devices. This objective requires overcoming several challenges at the level of computational modeling. The main one consists of addressing the multi-physics nature of the problem that combines free flow in channels with hindered flow in porous media. Fluid dynamics is also coupled with advection-diffusion-reaction equations that model the transport of biomolecules throughout the system and their interaction with living tissues and C constructs. Ultimately, we aim at providing a predictive approach useful for the general organ-on-chip community. To this end, we have developed a lumped parameter approach that allows us to analyze the behavior of multi-unit bioreactor systems with modest computational effort, provided that the behavior of a single unit can be fully characterized.