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.

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.

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.

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.

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.

Hydrodynamic and Geometric Behavior of Two Pericardial Prostheses Implanted in Small Aortic Roots.

Hydrodynamic performance of stented bioprostheses is far below that of the native valve. One of the reasons is that the internal diameter of the prosthesis is usually smaller than that of the native valve. However, other valve characteristics are also important in generating the pressure drop.

Human cardiac fibroblasts adaptive responses to controlled combined mechanical strain and oxygen changes in vitro.

Upon cardiac pathological conditions such as ischemia, microenvironmental changes instruct a series of cellular responses that trigger cardiac fibroblasts-mediated tissue adaptation and inflammation. A comprehensive model of how early environmental changes may induce cardiac fibroblasts (CF) pathological responses is far from being elucidated, partly due to the lack of approaches involving complex and simultaneous environmental stimulation. Here, we provide a first analysis of human primary CF behavior by means of a multi-stimulus microdevice for combined application of cyclic mechanical strain and controlled oxygen tension.

A Dual-Mode Bioreactor System for Tissue Engineered Vascular Models.

In the past decades, vascular tissue engineering has made great strides towards bringing engineered vascular tissues to the clinics and, in parallel, obtaining in-lab tools for basic research. Herein, we propose the design of a novel dual-mode bioreactor, useful for the fabrication (construct mode) and in vitro stimulation (culture mode) of collagen-based tubular constructs. Collagen-based gels laden with smooth muscle cells (SMCs) were molded directly within the bioreactor culture chamber.

Design of a simple coronary impedance simulator for the in vitro study of the complex coronary hemodynamics.

Several novel approaches were recently developed to treat aortic root pathologies. The alteration induced by some of these approaches to the biomechanics of the aortic root could possibly affect the coronary perfusion, compromising the procedural outcome. In this scenario, the need to replicate in vitro the coronary flow pattern in physiological and pathological conditions is becoming crucial for the functional assessment of novel devices and techniques.

Full Mimicking of Coronary Hemodynamics for Ex-Vivo Stimulation of Human Saphenous Veins.

After coronary artery bypass grafting, structural modifications of the saphenous vein wall lead to lumen narrowing in response to the altered hemodynamic conditions. Here we present the design of a novel ex vivo culture system conceived for mimicking central coronary artery hemodynamics, and we report the results of biomechanical stimulation experiments using human saphenous vein samples. The novel pulsatile system used an aortic-like pressure for forcing a time-dependent coronary-like resistance to obtain the corresponding coronary-like flow rate.

Comparison of the Performance of a Sutureless Bioprosthesis With Two Pericardial Stented Valves on Small Annuli: An In Vitro Study.

Background: Aortic valve replacement has evolved recently with the development of the sutureless bioprosthesis. One such valve is the Perceval bioprosthesis, which is built by mounting leaflets of bovine pericardium to a thin stent; this approach has the potential to provide an excellent fluid dynamic performance. We undertook an in vitro study to compare the hydrodynamic performance of the sutureless bioprosthesis with two standard pericardial stented bioprostheses (Crown and Magna).

Opening-closing pattern of four pericardial prostheses: results from an in vitro study of leaflet kinematics.

Pericardial and porcine stented aortic valves have different leaflet kinematics. To study the biomechanics of a prosthesis thoroughly, the in vitro setting is the most appropriate. The aim of our study was to find out whether the prosthesis design in which the pericardial sheet is outside the stent post might influence the opening and closing patterns of the leaflets.

Microfluidic approaches for the assessment of blood cell trauma: a focus on thrombotic risk in mechanical circulatory support devices.

Introduction: Mechanical circulatory support devices (MCSDs) are emerging as a valuable therapeutic option for the management of end-stage heart failure. However, although recipients are routinely administered with anti-thrombotic (AT) drugs, thrombosis persists as a severe post-implant complication. Conventional clinical assays and coagulation markers demonstrate partial ability in preventing the onset of thrombosis.

A Comprehensive Fluid Dynamic and Geometric Study for an "In-Vitro" Comparison of Four Surgically Implanted Pericardial Stented Valves.

Background And Aim Of The Study: Many variables may affect the fluid dynamic of an implanted bioprosthesis. In-vitro studies have provided accurate data such that, when different prostheses are implanted in the same true aortic root, it should be possible to make a fair comparison. The study aim was to evaluate the fluid dynamic and geometric characteristics of the four most widely used stented pericardial bioprostheses.

On-chip assessment of human primary cardiac fibroblasts proliferative responses to uniaxial cyclic mechanical strain.

Cardiac cell function is substantially influenced by the nature and intensity of the mechanical loads the cells experience. Cardiac fibroblasts (CFs) are primarily involved in myocardial tissue remodeling: at the onset of specific pathological conditions, CFs activate, proliferate, differentiate, and critically alter the amount of myocardial extra-cellular matrix with important consequences for myocardial functioning. While cyclic mechanical strain has been shown to increase matrix synthesis of CFs in vitro, the role of mechanical cues in CFs proliferation is unclear.