(1) Background: This study aimed to analyse the hydrodynamic performance of two generations of self-expanding transcatheter heart valves (THV) as a valve-in-valve (ViV) in different surgical aortic valve (SAV) models under standardised conditions. The nitinol-based Evolut R valve is frequently used in ViV procedures. It is unclear whether its successor, the Evolut PRO, is superior in ViV procedures, particularly considering the previously implanted SAV model. (2) Methods: EvolutTM R 26 mm and EvolutTM PRO 26 mm prostheses were implanted in nine 21 mm labelled size SAV models (Hancock® II, Mosaic® UltraTM, EpicTM Supra, TrifectaTM GT, Perimount®, Perimount® Magna Ease, AvalusTM, IntuityTM, Freestyle®) to analyse their hydrodynamic performance under defined circulatory conditions in a pulse duplicator. (3) Results: Both THVs presented with the lowest effective orifice area (EOA) and highest mean pressure gradient (MPG) inside Hancock® II, whereas THVs in Intuity showed the highest EOA and lowest MPG. Evolut R and Evolut PRO showed significant hydrodynamic differences depending on the SAV. Both THVs performed similarly in porcine valves. Although the Evolut R performed better than Evolut PRO in stented bovine SAVs, the Evolut PRO was superior inside the Intuity. Further, the SAV model design markedly influenced the TAV\'s geometric orifice area and pin-wheeling index. (4) Conclusions: These findings show that the Evolut R and Evolut PRO perform differently depending on the previously implanted SAV model. THV selection for treatment of a specific SAV model should consider these results.

Cardiovascular pressure sensors require dedicated, reliable, and customisable performance testing equipment. Devices available on the market, such as pulsatile pumps and pulse multipliers, offer limited adaptability to the needs of pressure sensor testing or are highly complex tools designed for other purposes. Therefore, there is a strong need to provide an adaptable and versatile device for characterisation during prototype development, prior to animal model testing. Early development requires detailed characterisation of a sensor performance in a realistic environmental scenario. To address this need, we adapted an off-the-shelf pressure chamber with a custom Arduino-based controller to achieve a rapid change in pressure that simulates the pulsatile profile of human blood pressure. The system is a highly customisable tool, and we have experimentally shown that it works successfully in a wide range of pressures from 30 mmHg to 400 mmHg with a resolution of 2 mmHg. By adjusting the chamber volume using a water balloon, we achieved a cycle rate of up to 120 beats per minute. The device can be operated directly from the Arduino IDE or with a customised graphical user interface developed by our research group. The proposed system is intended to assist other researchers in the development of industrial and biomedical pressure sensors.

Three-dimensional printing is increasingly used in the health care industry. Making patient-specific anatomic task trainers has been one of the more commonly described uses of this technique specifically, allowing surgeons to perform complex procedures on patient-specific models in a nonoperative setting. With regard to transesophageal echocardiography (TEE) training, commercially available simulators have been increasingly used. Even though these simulators are haptic in nature and anatomically near realistic, they lack patient specificity and the training of the dynamic workflow and imaging protocol used in the operative setting. Herein a customized pulsatile left-sided heart model that uses patient-specific 3-dimensional printed valves under physiological intracardiac pressures as a TEE task trainer is described. With this model, dynamic patient-specific valvular anatomy can be visualized with actual TEE machines by trainees to familiarize themselves with the surgery equipment and the imaging protocol.

BACKGROUND: Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections.
RESULTS: An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics.
CONCLUSIONS: We have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the simultaneous measurement of all different quantities of interest for haemodynamic performance and the analysis of their mutual interactions.

The potential of polymeric heart valves (PHV) prostheses is to combine the hemodynamic performances of biological valves with the durability of mechanical valves. The aim of this work is to design and develop a new tri-leaflet prosthetic heart valve (HV) made from styrenic block copolymers. A computational finite element model was implemented to optimize the thickness of the leaflets, to improve PHV mechanical and hydrodynamic performances. Based on the model outcomes, 8 prototypes of the designed valve were produced and tested in vitro under continuous and pulsatile flow conditions, as prescribed by ISO 5840 Standard. A specially designed pulse duplicator allowed testing the PHVs at different flow rates and frequency conditions. All the PHVs met the requirements specified in ISO 5840 Standard in terms of both regurgitation and effective orifice area (EOA), demonstrating their potential as HV prostheses.

OBJECTIVE: To evaluate the feasibility of obtaining hemodynamic metrics of echocardiographically derived 3-dimensional printed mitral valve models deployed in a pulse-duplicator chamber.
METHODS: Exploratory study.
METHODS: Tertiary-care university hospital.
METHODS: Percutaneous MitraClip procedure patient.
METHODS: Three-dimensional R-wave gated, full-volume transesophageal echocardiography images were obtained after deployment of the MitraClip device. A high-quality diastolic frame of the mitral valve was segmented using Mimics Innovation Suite and merged with a flange. The data were exported as a stereolithography (.stl) file, and a rigid 3-dimensional model was printed using a MakerBot Replicator 2 printer. A flexible silicone cast then was created and deployed in the pulse-duplicator chamber filled with a blood-mimicking fluid.
RESULTS: The authors were able to obtain continuous-wave Doppler tracings of the valve inflow with a transesophageal echocardiography transducer. They also were able to generate diastolic ventricular and atrial pressure tracings. Pressure half-time and mitral valve area were computed from these measurements.
CONCLUSIONS: This pulse duplicator shows promising applications in hemodynamic testing of patient-specific anatomy. Future modifications to the system may allow for visualization and data collection of gradients across the aortic valve.

Pediatric patients account for a small portion of the heart valve replacements performed, but a pediatric pulmonary valve replacement with growth potential remains an unmet clinical need. Herein we report the first tubular heart valve made from two decellularized, engineered tissue tubes attached with absorbable sutures, which can meet this need, in principle. Engineered tissue tubes were fabricated by allowing ovine dermal fibroblasts to replace a sacrificial fibrin gel with an aligned, cell-produced collagenous matrix, which was subsequently decellularized. Previously, these engineered tubes became extensively recellularized following implantation into the sheep femoral artery. Thus, a tubular valve made from these tubes may be amenable to recellularization and, ideally, somatic growth. The suture line pattern generated three equi-spaced leaflets in the inner tube, which collapsed inward when exposed to back pressure, per tubular valve design. Valve testing was performed in a pulse duplicator system equipped with a secondary flow loop to allow for root distention. All tissue-engineered valves exhibited full leaflet opening and closing, minimal regurgitation (<5%), and low systolic pressure gradients (<2.5 mmHg) under pulmonary conditions. Valve performance was maintained under various trans-root pressure gradients and no tissue damage was evident after 2 million cycles of fatigue testing.

BACKGROUND: The majority of bioprosthetic venous valves do not have a sinus pocket and, in practice, they are often placed in non-sinus segments of the veins. The aim of this study is to investigate the effect of the sinus pocket on the flow dynamics in a prosthetic valve.
METHODS: A bench top in vitro experiment was set up at physiological flow conditions to simulate the flow inside a venous system. Bicuspid bioprosthetic valves with different leaflet lengths (5 and 10 mm) were tested in tubes with and without a sinus pocket and the flows around the valve were visualized by particle image velocimetry (PIV). Velocity data measurements were made and the vorticity was calculated in the with- and without-sinus set-ups.
RESULTS: PIV measurements showed that vortex structure was maintained by the sinus. For the 10-mm leaflet length design with sinus, the jet width at the exit of the valve was 59% of that without sinus. For the 5-mm design with sinus, the jet width was 73% of the valve without sinus. Flow from the sinus region was entrained into the main jet observed near the exit of the sinus and altered the flow at the near wall region.
CONCLUSIONS: The sinus pocket alters the flow around the valve and functions as flow regulator to smooth the flow pattern around the valve. The vortical structure inside the sinus is maintained at the valve leaflet tip during the valve cycle. For the prosthetic valve designated to be placed without a sinus, a shorter leaflet length is preferable and performs more closely to the valve with sinus.