We present a novel framework for the fluid dynamics analysis of healthy subjects and patients affected by ascending thoracic aorta aneurysm (aTAA). Our aim is to obtain indications about the effect of a bulge on the hemodynamic environment at different enlargements. Three-dimensional (3D) surface models defined from healthy subjects and patients with aTAA, selected for surgical repair, were generated. A representative shape model for both healthy and pathological groups has been identified. A morphing technique based on radial basis functions (RBF) was applied to mold the shape relative to healthy patient into the representative shape of aTAA dataset to enable the parametric simulation of the aTAA formation. Computational fluid dynamics (CFD) simulations were performed by means of a finite volume solver using the mean boundary conditions obtained from three-dimensional (PC-MRI) acquisition. Blood flow helicity and flow descriptors were assessed for all the investigated models. The feasibility of the proposed integrated approach pertaining the coupling between an RBF morphing technique and CFD simulation for aTAA was demonstrated. Significant hemodynamic changes appear at the 60% of the bulge progression. An impingement of the flow toward the bulge was observed by analyzing the normalized flow eccentricity (NFE) index.

The importance of experimental setups able to reproduce cardiac functions was well established in the field of clinical innovations. The mock circulatory loops acquired rising relevance, and the possibility to have a complete reproduction of different and specific fluid dynamic conditions within the setup is pivotal. A system with enough versatility to reproduce the physiologic range of both flows and pressures is required. This study describes the design of a versatile setup composed by a custom pulsatile left ventricular pump system and a 3D-printed mock circulatory loop for the in vitro analysis of a patient-specific case of an aortic complex. The performances of the pump were validated first with a set of test flow profiles. It was demonstrated that the system was able to cover a wide range of aortic and mitral flows. Second, the pump system was inserted within the full mock circulatory loop. A patient-specific case was reproduced, both in terms of flow and pressure profiles. A successful validation of the flow and pressure waveforms was obtained by using patient-specific in vivo data from magnetic resonance analysis.

Goal: This work presents the development of a Hybrid Mock Circulatory Loop (HMCL) to simulate hemodynamics at patient-specific level in terms of both 3D geometry and inlet/outlet boundary conditions. Methods: Clinical data have been processed to define the morphological and functional patient-specific settings. A piston pump is used to impose a parametric flow rate profile at the inlet of the hemodynamic circuit. In order to guarantee the physiological pressure and flow conditions, a specific hybrid chamber system including a real-time control has been designed and implemented. The developed system was validated firstly in a single outlet branch model and, secondly, on a 3D printed patient-specific multi-branch phantom. Finally, for the 3D phantom, the outlet flow profiles were compared with the corresponding in-vivo flow data. Results: Results showed that the root mean squared error between the prescribed setpoint and the measured pressures was always below 3 mmHg (about 2.5%) for all cases. The obtained flow profiles for the patient-specific model were in agreement with the related functional in-vivo data. Significance: The capability to reproduce physiological hemodynamics condition, with high-fidelity, plays a significant role in the cardiovascular research. The developed platform can be used to assess the performances of cardiovascular devices, to validate numerical simulations, and to test imaging systems.

Atrial Fibrillation (AF) is a common disease that significantly increases the risk of strokes. Oral anticoagulants represent the standard preventive treatment, but they involve severe drawbacks, including intracerebral bleedings. Since in patients affected by nonvalvular AF, the Left Atrial Appendage (LAA) is the primary source of thromboembolism, percutaneous closure of the LAA is a viable option for people unsuitable for long-term anticoagulant therapy. However, the complexities related to the implant procedure, occlusion devices and the anatomical variability hinder the pre-operative planning, resulting in unexpected outcomes. In this context, in-silico models may represent a powerful support tool providing clinicians with more detailed information. Nevertheless, few works focusing on numerical modeling of LAA occlusion devices have been presented so far, and a detailed process to assess the model credibility, verifying that different sources of uncertainty did not affect the prediction, is missing. This work aims to illustrate a process that allows to build and validate the numerical model of a commercial occlusion device starting from only one sample available and without data provided by the manufacturer. To better identify potential uncertainties, the validation followed a step-by-step process that led from individual device behavior assessment to interaction with deformable conduit evaluation.

The venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a widely adopted procedure to provide oxygenated blood support in patients who underwent cardiac shock. The current work presents a study to define a correlation between VA-ECMO support level and both systemic pressure and arterial perfusion. In this work, a numerical approach is defined on a patient-specific aortic geometry to validate this trend on a more complete case and also to investigate the behavior of the mixing zone. In particular, morphological data from computed tomography imaging of a patient-specific whole aorta, including supra aortic vessels, coronaries, and renal arteries, were adopted for the study. A computational fluid dynamic approach was set for the analysis. A total of three cardiogenic shock cases (mild, medium, and severe) were simulated. For each shock configuration, different levels of ECMO support were simulated (0–6 l/min flow range). The aortic fluid dynamics were evaluated in terms of systemic afterload, watershed zone position, and perfusion of arteries. A linear trend of the perfusion as a function of ECMO level support was investigated and successfully validated. The minimum level of ECMO support to grant the perfusion of all arteries, causing the minimum possible afterload increase, was individuated and fitted with a linear model against different levels of cardiogenic shock. The results presented demonstrated to be a first step to have a preliminary tool to establish the minimum level of ECMO support for overall perfusion as a function of cardiogenic shock percentage.