Coronary Perfusion After Valve-in-Valve Transcatheter Aortic Valve Implantation in Small Aortic Root: In Vitro Experimental Assessment.

Coronary flow obstruction following transcatheter aortic valve-in-valve implantation (VIV-TAVI) is associated with a high mortality risk. The aim of this work was to quantify the coronary perfusion after VIV-TAVI in a high-risk aortic root anatomy. 3D printed models of small aortic root were used to simulate the implantation of a TAVI prosthesis (Portico 23) into surgical prostheses (Trifecta 19 and 21).

Impedance-Based Rapid Diagnostic Tool for Single Malaria Parasite Detection.

This paper presents a custom, low-cost electronic system specifically designed for rapid and quantitative detection of the malaria parasite in a blood sample. The system exploits the paramagnetic properties of malaria-infected red blood cells (iRBCs) for their magnetophoretic capture on the surface of a silicon chip. A lattice of nickel magnetic micro-concentrators embedded in a silicon substrate concentrates the iRBCs above coplanar gold microelectrodes separated by 3 μm for their detection through an impedance measurement.

Morphometric Characterization of an Ex Vivo Porcine Model of Functional Tricuspid Regurgitation.

Emerging treatments for tricuspid valve (TV) regurgitation require realistic TV pathological models for preclinical testing. The aim of this work was to investigate structural features of fresh and defrosted porcine right-heart samples as models of mild and severe functional tricuspid regurgitation (FTR) condition in ex-vivo pulsatile flow platform. Ten fresh hearts were tested ex-vivo under steady and pulsatile flow in typical right-heart loading conditions.

Development and Validation of a Novel Skills Training Model for PCNL, an ESUT project.

Background And Aim: The aim of this study is to validate a totally non biologic training model that combines the use of ultrasound and X ray to train Urologists and Residents in Urology in PerCutaneous NephroLithotripsy (PCNL).

Methods: The training pathway was divided into three modules: Module 1, related to the acquisition of basic UltraSound (US) skill on the kidney; Module 2, consisting of correct Nephrostomy placement; and Module 3, in which a complete PCNL was performed on the model. Trainees practiced on the model first on Module 1, than in 2 and in 3.

Hybrid fibroin/polyurethane small-diameter vascular grafts: from fabrication topreliminary assessment.

To address the need of alternatives to autologous vessels for small-calibre vascular applications (e.g. cardiac surgery), a bio-hybrid semi-degradable material composed of silk fibroin (SF) and polyurethane (Silkothane®) was herein used to fabricate very small-calibre grafts (Ø= 1.

On-chip magnetophoretic capture in a model of malaria-infected red blood cells.

The search for new rapid diagnostic tests for malaria is a priority for developing an efficient strategy to fight this endemic disease, which affects more than 3 billion people worldwide. In this study, we characterize systematically an easy-to-operate lab-on-chip, designed for the magnetophoretic capture of malaria-infected red blood cells (RBCs). The method relies on the positive magnetic susceptibility of infected RBCs with respect to blood plasma.

Commissural repositioning in bicuspid aortic valve repair: an in vitro acute model to explore and explain different results.

Objectives: Commissural orientation <160° is a recognized risk factor for bicuspid aortic valve repair failure. Based on this observation, repairing this subtype of aortic valve by reorienting the 2 commissures at 180° has recently been proposed.

Methods: Nine porcine hearts with aortic annulus diameters of 25 mm were selected.

A Lab-On-chip Tool for Rapid, Quantitative, and Stage-selective Diagnosis of Malaria.

Malaria remains the most important mosquito-borne infectious disease worldwide, with 229 million new cases and 409.000 deaths in 2019. The infection is caused by a protozoan parasite which attacks red blood cells by feeding on hemoglobin and transforming it into hemozoin.

Ex Vivo Model of Functional Mitral Regurgitation Using Deer Hearts.

Transcatheter therapies are emerging for functional mitral regurgitation (FMR) treatment, however there is lack of pathological models for their preclinical assessment. We investigated the applicability of deer hearts for this purpose.8 whole deer hearts were housed in a pulsatile flow bench.

On-Chip Selective Capture and Detection of Magnetic Fingerprints of Malaria.

The development of innovative diagnostic tests is fundamental in the route towards malaria eradication. Here, we discuss the sorting capabilities of an innovative test for malaria which allows the quantitative and rapid detection of all malaria species. The physical concept of the test exploits the paramagnetic property of infected erythrocytes and hemozoin crystals, the magnetic fingerprints of malaria common to all species, which allows them to undergo a selective magnetophoretic separation driven by a magnetic field gradient in competition with gravity.

Fluid dynamics characterization and thrombogenicity assessment of a levitating centrifugal pump with different impeller designs.

Technical guidelines nowadays recommend and regulate the use Computational Fluid Dynamics (CFD) to assess the performance of medical devices. CFD coupled to blood damage models has emerged as a powerful tool to evaluate the hemocompatibility of blood recirculating devices. The present study is aimed at evaluating the hydrodynamic performance and the thrombogenic potential of two prototypes of magnetically levitating centrifugal pumps.

Coronary artery mechanics induces human saphenous vein remodelling recruitment of adventitial myofibroblast-like cells mediated by Thrombospondin-1.

: Despite the preferred application of arterial conduits, the greater saphenous vein (SV) remains indispensable for coronary bypass grafting (CABG), especially in multi-vessel coronary artery disease (CAD). The objective of the present work was to address the role of mechanical forces in the activation of maladaptive vein bypass remodeling, a process determining progressive occlusion and recurrence of ischemic heart disease. : We employed a custom bioreactor to mimic the coronary shear and wall mechanics in human SV vascular conduits and reproduce experimentally the biomechanical conditions of coronary grafting and analyzed vein remodeling process by histology, histochemistry and immunofluorescence.

Positive impact of dynamic seeding of mesenchymal stem cells on bone-like biodegradable scaffolds with increased content of calcium phosphate nanoparticles.

One of the main aims of bone tissue engineering, regenerative medicine and cell therapy is development of an optimal artificial environment (scaffold) that can trigger a favorable response within the host tissue, it is well colonized by resident cells of organism and ideally, it can be in vitro pre-colonized by cells of interest to intensify the process of tissue regeneration. The aim of this study was to develop an effective tool for regenerative medicine, which combines the optimal bone-like scaffold and colonization technique suitable for cell application. Accordingly, this study includes material (physical, chemical and structural) and in vitro biological evaluation of scaffolds prior to in vivo study.

Fluid-Structure Interaction and In Vitro Analysis of a Real Bileaflet Mitral Prosthetic Valve to Gain Insight Into Doppler-Silent Thrombosis.

Prosthetic valve thrombosis (PVT) is a serious complication affecting prosthetic heart valves. The transvalvular mean pressure gradient (MPG) derived by Doppler echocardiography is a crucial index to diagnose PVT but may result in false negatives mainly in case of bileaflet mechanical valves (BMVs) in mitral position. This may happen because MPG estimation relies on simplifying assumptions on the transvalvular fluid dynamics or because Doppler examination is manual and operator dependent.

Prothrombotic activity of cytokine-activated endothelial cells and shear-activated platelets in the setting of ventricular assist device support.

Background: We systematically analyzed the synergistic effect of: (i) cytokine-mediated inflammatory activation of endothelial cells (ECs) with and (ii) shear-mediated platelet activation (SMPA) as a potential contributory mechanism to intraventricular thrombus formation in the setting of left ventricular assist device (LVAD) support.

Methods: Intact and shear-activated human platelets were exposed to non-activated and cytokine-activated ECs. To modulate the level of LVAD-related shear activation, platelets were exposed to shear stress patterns of varying magnitude (30, 50, and 70 dynes/cm, 10 minutes) via a hemodynamic shearing device.

Versican is differentially regulated in the adventitial and medial layers of human vein grafts.

Changes in extracellular matrix proteins may contribute significantly to the adaptation of vein grafts to the arterial circulation. We examined the production and distribution of versican and hyaluronan in intact human vein rings cultured ex vivo, veins perfused ex vivo, and cultured venous adventitial and smooth muscle cells. Immunohistochemistry revealed higher levels of versican in the intima/media compared to the adventitia, and no differences in hyaluronan.

Microfluidic flow-based platforms for induction and analysis of dynamic shear-mediated platelet activation-Initial validation versus the standardized hemodynamic shearing device.

A microfluidic flow-based platform (μFP), able to stimulate platelets via exposure of shear stress patterns pertinent to cardiovascular devices and prostheses, was compared to the Hemodynamic Shearing Device (HSD)-a state-of-the-art bench-top system for exposure of platelets to defined levels and patterns of shear. Platelets were exposed to time-varying shear stress patterns in the two systems; in detail, platelets were recirculated in the μFP or stimulated in the HSD to replicate comparable exposure time. Shear-mediated platelet activation was evaluated via (i) the platelet activity state assay, allowing the measurement of platelet-mediated thrombin generation and associated prothrombotic tendencies, (ii) scanning electron microscopy to evaluate morphological changes of sheared platelets, and (iii) flow cytometry for the determination of platelet phosphatidylserine exposure as a marker of shear activation.

Assembly of Tissue-Engineered Blood Vessels with Spatially Controlled Heterogeneities.

Tissue-engineered human blood vessels may enable in vitro disease modeling and drug screening to accelerate advances in vascular medicine. Existing methods for tissue-engineered blood vessel (TEBV) fabrication create homogenous tubes not conducive to modeling the focal pathologies characteristic of certain vascular diseases. We developed a system for generating self-assembled human smooth muscle cell (SMC) ring units, which were fused together into TEBVs.

Routine clinical anti-platelet agents have limited efficacy in modulating hypershear-mediated platelet activation associated with mechanical circulatory support.

Introduction: Continuous flow ventricular assist devices (cfVADs) continue to be limited by thrombotic complications associated with disruptive flow patterns and supraphysiologic shear stresses. Patients are prescribed complex antiplatelet therapies, which do not fully prevent recurrent thromboembolic events. This is partially due to limited data on antiplatelet efficacy under cfVAD-associated shear conditions.

Dry versus hydrated collagen scaffolds: are dry states representative of hydrated states?

Collagen composite scaffolds have been used for a number of studies in tissue engineering. The hydration of such highly porous and hydrophilic structures may influence mechanical behaviour and porosity due to swelling. The differences in physical properties following hydration would represent a significant limiting factor for the seeding, growth and differentiation of cells in vitro and the overall applicability of such hydrophilic materials in vivo.

Experimental quantification of the fluid dynamics in blood-processing devices through 4D-flow imaging: A pilot study on a real oxygenator/heat-exchanger module.

The performance of blood-processing devices largely depends on the associated fluid dynamics, which hence represents a key aspect in their design and optimization. To this aim, two approaches are currently adopted: computational fluid-dynamics, which yields highly resolved three-dimensional data but relies on simplifying assumptions, and in vitro experiments, which typically involve the direct video-acquisition of the flow field and provide 2D data only. We propose a novel method that exploits space- and time-resolved magnetic resonance imaging (4D-flow) to quantify the complex 3D flow field in blood-processing devices and to overcome these limitations.

Modeling of Internal Filtration in Theranova Hemodialyzers.

High retention onset (HRO) is the designation for a new class of hemodialysis membranes. A unique characteristic of this class is the highly selective and controlled porosity resulting in sieving properties that provide a clinically desirable balance between middle/large molecular weight solute removal and albumin loss. Another defining feature of this membrane class is the relatively small fiber diameter, which produces high convective volumes in the form of internal filtration.

Microfludic platforms for the evaluation of anti-platelet agent efficacy under hyper-shear conditions associated with ventricular assist devices.

Thrombus formation is a major adverse event affecting patients implanted with ventricular assist devices (VADs). Despite anti-thrombotic drug administration, thrombotic events remain frequent within the first year post-implantation. Platelet activation (PA) is an essential process underling thrombotic adverse events in VAD systems.