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European Society of Biomechanics - Italian Chapterwas organised in Massa, Italy on 6 and 7th October2022 in which the abstract titled "Polymers in Drug Coated Balloon Angioplasty and its Coating Morphology"was accpeted for poster presentation. The abstract gives a description of the mechanical tests performed on the drug coated angioplasty balloons and the respective results.&nbsp

European Society of Biomaterials was organised in Bordeaux, France from 4 to 8th of August 2022 in which the abstract titled "Mechanical and surface characterization of Drug Coated Balloons"was accpeted for poster presentation under the sessionMechanical & physico-chemical characterization. The abstract gives a description of the mechanical tests performed on the drug coated angioplasty balloons and the respective results.&nbsp

Clinical observation of condensation at the gas flow exit of blood oxygenators is a recurrent event during cardiopulmonary bypass. These devices consist of a bundle of hollow fibers made of a microporous membrane that allows the exchange of O2 and CO2. The fibers carry a gas mixture inside (intraluminal flow), while blood flows externally around them (extraluminal flow). Although different studies described this effect in the past, the specific role of the different sections of the device requires further analysis, and the total condensation rate remains unquantified. In this study, a closer look is taken at the transition of gas between the oxygenation bundle and the external room air. A method is proposed to estimate the total condensate output, combining computational fluid dynamics (CFD) of thermal distribution and a simplified 1D model of water vapor saturation of gas. The influence of a number of different parameters is analyzed, regarding material properties, environmental conditions, and clinical use. Results show that condensation rate could vary in a 30‐fold range within reasonably small variations of the different variables considered.

International audience; Inverse problems in cardiovascular modelling have become increasingly important to assess each patient individually. These problems entail estimation of patient-specific model parameters from uncertain measurements acquired in the clinic. In recent years, the method of data-assimilation, especially the unscented Kalman filter, has gained popularity to address computational efficiency and uncertainty consideration in such problems. This work highlights and presents solutions to several challenges of this method pertinent to models of cardiovascular haemodynamics. These include methods to a) avoid ill-conditioning of covariance matrix; b) handle a variety of measurement types; c) include a variety of prior knowledge in the method; and d) incorporate measurements acquired at different heart-rates, a common situation in the clinic where patient-state differs between various clinical acquisitions. Results are presented for two patient-specific cases of congenital heart disease. To illustrate and validate data-assimilation with measurements at different heart-rates, results are presented on synthetic data-set and on a patient-specific case with heart valve regurgitation. It is shown that the new method significantly improves the agreement between model predictions and measurements. The developed methods can be readily applied to other pathophysiologies and extended to dynamical systems which exhibit different responses under different sets of known parameters or different sets of inputs (such as forcing/excitation frequencies).

Computational fluid dynamics (CFD) can have a complementary predictive role alongside the exquisite visualization capabilities of 4D cardiovascular magnetic resonance (CMR) imaging. In order to exploit these capabilities (e.g. for decision-making) it is necessary to validate computational models against real world data. In this study we sought to acquire 4D CMR flow data in a controllable, experimental setup and use these data to validate a corresponding computational model. We applied this paradigm to a case of congenital heart disease, namely transposition of the great arteries (TGA) repaired with arterial switch operation (ASO). For this purpose, a mock circulatory loop compatible with the CMR environment was constructed and two detailed aortic 3D models (i.e. one TGA case and one normal aortic anatomy) were tested under realistic hemodynamic conditions, acquired 4D CMR flow. The same 3D domains were used for multi-scale CFD simulations, whereby the remainder of the mock circulatory system was appropriately summarized with a lumped parameter network (LPN). Boundary conditions of the simulations mirrored those measured in vitro. Results showed a very good quantitative agreement between experimental and computational models in terms of pressure (overall maximum % error = 4.4% aortic pressure in the control anatomy) and flow distribution data (overall maximum % error = 3.6% at the subclavian artery outlet of the TGA model). Very good qualitative agreement could also be appreciated in terms of streamlines, throughout the cardiac cycle. Additionally, velocity vectors in the ascending aorta revealed less symmetrical flow in the TGA model, which also exhibited higher wall shear stress in the anterior ascending aorta.

According to a number of clinical studies, coronary aspiration catheters are useful tools to remove a thrombus (blood clot) blocking a coronary artery. However, these thrombectomy devices may fail to remove the blood clot entirely. Few studies have been devoted to a systematic analysis of factors affecting clot aspiration. The geometric characteristics of the aspiration catheter, the physical properties of the thrombus, and the applied vacuum pressure are crucial parameters. In this study, the aspiration of a blood clot blocking a coronary bifurcation is computationally simulated. The clot is modeled as a highly viscous fluid, and a two-phase (blood and clot) problem is solved. The effects of geometric variations in the tip of the coronary catheter, including lateral hole size and location, are investigated considering different aspiration pressures and clot viscosities. A Bird-Carreau model is adopted for blood viscosity, while a power law model is used to describe the clot rheology. Computational results for blood clot aspiration show that the presence of holes in the lateral part of the tip of the catheter can be beneficial depending on clot viscosity, hole features, and applied aspiration pressure. In general, the holes are beneficial when the clot viscosity is low, while aspiration catheters without any extra lateral holes exhibit better performance for higher clot viscosity. However, when higher aspiration pressures are applied, the catheters tend to behave relatively similarly in removing clots with various viscosities, reducing the role of the clot viscosity.

International audience; To assess the efficacy of stenting procedure in the treatment of cerebral aneurysms, a tool predicting accurately and with fast execution time the stent released configuration could be very useful. The aim of this work is to propose a first validation of the Fast Virtual Stenting method by comparing its results with the ones achieved with Finite Element Analysis. A series of parametric models has been set varying the geometries of the stent, the vessel and the aneurysmal neck, and the differences between the two methods have been evaluated comparing the released configurations in corresponding models. Results show a quite fine match between the two methodologies, accompanied by a significant reduction in the computational costs gained with FVS. In this way, this method seems to be a promising tool to help clinicians choosing the best treatment option.

The umbilical cord is a conduit between the developing foetus and the placenta. In physiological conditions it contains two arteries and one vein immersed in a mucoid tissue called Wharton׳s jelly. Although the extreme importance of such a structure is fully recognized, the umbilical cord and its components have been scarcely studied. A deep investigation on the biomechanics of the umbilical cord could help to understand if the pregnancy outcome is influenced by umbilical cord mechanical properties, however, detailed biomechanical data are still lacking. In the present study, the mechanical properties during compression of the human Wharton׳s jelly have been evaluated using a poroelastic approach. Multi-ramp stress-relaxation tests in both confined and unconfined configurations were performed on Wharton׳s jelly samples extracted from foetal and placental sides of twenty human umbilical cords. The Young modulus and Aggregate modulus were calculated at three strain levels and the hydraulic permeability was found by fitting the confined stress-relaxation data to the analytical solution and minimizing the stress least square differences. The Wharton׳s jelly exhibits a highly non linear and viscoelastic behaviour showing a dependence on the applied strain values and a ~90% and ~85% relaxation in unconfined and confined configuration, respectively. Moreover, equilibrium Young and Aggregate moduli resulted significantly higher and the permeability significantly lower at the foetal than the placental site, showing a dependence of the three material parameters on the location (foetal or placental) and, consequently, a non-homogeneity in the Wharton׳s jelly mechanical properties.