(Bio)Artificial Organs

The functional properties of electroceramic thin films can be degraded by subtractive patterning techniques used for MEMS applications. This work explores an alternative deposition technique, where lead zirconate titanate (PZT) liquid precursors are printed onto substrates in a desired geometry from stamp wells (rather than stamp protrusions). Printing from wells significantly increased sidewall angles (from ~1 to greater than 35 degrees) relative to printing solutions from stamp protrusions. Arrays of PZT features were printed, characterized, and compared to continuous PZT thin films of similar thickness. 300 nm thick printed PZT features exhibit a permittivity of 730 and a loss tangent of 0.022. The features showed remanent polarizations of 26 µC/cm 2 , and coercive fields of 95 kV/cm. The piezoelectric response of the features produced an e 31,f of-5.2 C/m 2. This technique was also used to print directly atop prepatterned substrates. Optimization of printing parameters yielded patterned films with 90° sidewalls. Lateral feature sizes ranged from hundreds of microns down to 1µm. In addition, several device designs were pre-patterned onto SOI wafers (Si/SiO 2 /Si with thicknesses of 0.35/1/500 µm). The top patterned silicon was released from the underlying material, and PZT was directly printed and crystallized on the free-standing structures in order to provide actuation and sensing capabilities to the device.

The convex bileaflet valve replaces the flat biflap inflow valve designed by Long Sheng Yu and the tricusp semilunair outflow valve. One reason is easier manufacturing. Convex bileaflet valves are developed for the 11, 20, 40, 70 and 140cc ventricles. Testing included curves (Cardiac Output versus Venous Pressure, Cardiac Output versus Heart rate), flow visualization studies, paint and bloodbag studies. The curves and flow visualization were done by connecting ventricles to one of our standard mock circulations. Paint and bloodbag studies were done by connecting the hearts to a bloodbag, but the bag was filled with water for the paint studies. The curves show high cardiac output, even with pumping at high heart rates (150 BPM+). The flow visualization shows a good stream through the sinus Valsalvae. No stagnating flow is visible. The bloodbag studies which provoke thrombosis show it on the edges of the heart valves, and little in the groove between the valve and the sinus Valsalvae. Heparninzation prevents the thrombosis. Results of our tests were good. The convex bileaflet valve seems to have good future.

Renal failure results in poisoning because metabolic by-products are not promptly removed from the body. The main remedy for this condition is hemo-dialysis, where blood bypasses the kidneys and is filtered in a-dialyzer‖, stationary machine. This research proposes and verifies novel techniques that allow an implantable device to replace a dialysis machine. This device would perform two important kidney functions: filtering solids and retaining desired electrolytes and small proteins. Three independent approaches are proposed and experimentally verified. The first approach is design optimization of the glomerular membrane as an implantable filter to separate blood cells from whole blood. We studied the parameters that minimized pressure drop per unit area in micro-channels (straight and diverging) with circular cross-sections.

Improving the inflow characteristics of the right ventricular function and pulmonary circulatory hemodynamics was essential for more precise evaluation of newly designed heart valves. To examine a pulmonary hemodynamics, the authors have been developing a pulmonary mechanical mock circulatory system. In this study, the pneumatically driven right atrium model was newly developed for clarifying the effect of atrial contraction on the dynamic behavior of pulmonary prosthetic valves. We focused on the hemodynamic behavior of the outflow mechanical heart valve of the right ventricle that could be affected by the right atrial dynamic motion. A medical-grade bileaflet valve was employed and installed into the outflow portion of the right ventricle model and examined its changes in hemodynamic behavior caused by the active right atrial contraction. With the active atrial contraction, hemodynamic waveforms of either the right ventricle or atrium were obtained using the modified pulmonary mock circulatory system. The characteristics with atrial contraction were well simulated as the natural hemodynamics. The right ventricular output increased by around 5% and the peak regurgitant flow at the moment of valve closing significantly decreased by the presence of the atrial contraction. Our mechanical circulatory system could simulate the end-diastolic right ventricular inflow characteristics. We found that the atrial contraction under the low pressure condition such as pulmonary circulation promoted earlier valve closing and prolonged closing duration of prosthetic valve. The simulation of right atrial contraction was important in the quantitative examination of right heart prosthetic valves for congenital heart malformation.

Beat-to-beat stability of implonted pacemakers, A method of measuring and analyzing beat-to-beat interval stability of implanted pacemaiters has been devised, and a number of normal and failing pacers have been studied in this way. It WQS seen that normal pacer rates were remarkably stable, but that abnormalities in beat-to-beat interval were found in 67.4% of all failing pacers. The ohnormalities consisted primarily of excessive interval (rate) scatter, linear and cyclic fluctuation, and transients following appiication of a magnet. It is expected that in problem cases a beat-to-beat analysis will be of help in differentiating normal from abnormal pacer function, and will provide confirmation signs of pacer failure: it may also uncover unusual and heretofore unpredictable failure modes.

Beat-to-beat stability of implonted pacemakers, A method of measuring and analyzing beat-to-beat interval stability of implanted pacemaiters has been devised, and a number of normal and failing pacers have been studied in this way. It WQS seen that normal pacer rates were remarkably stable, but that abnormalities in beat-to-beat interval were found in 67.4% of all failing pacers. The ohnormalities consisted primarily of excessive interval (rate) scatter, linear and cyclic fluctuation, and transients following appiication of a magnet. It is expected that in problem cases a beat-to-beat analysis will be of help in differentiating normal from abnormal pacer function, and will provide confirmation signs of pacer failure: it may also uncover unusual and heretofore unpredictable failure modes.

Renal Solutions Allient Sorbent Hemodialysis System utilizes a two-chambered pneumatic pump (Pulsar Blood Pump, Renal Solutions, Inc., Warrendale, PA, USA) to avoid limitations associated with peristaltic pumping systems. Single-needle access is enabled by counter-pulsing the two pump chambers, thereby obviating compliance chambers or blood reservoirs. Each chamber propels 20 cc per pulse of 3 s (dual access) or 6 s (single access) duration, corresponding to a peak Reynolds number of approximately 8000 (based on inlet velocity and chamber diameter). A multimodal series of flow visualization studies (tracer particle, dye washout, and dye erosion) was conducted on a sequence of pump designs with varying port locations and diaphragms to improve the geometry with respect to risk of thrombogenesis. Experiments were conducted in a

White hybrid light‐emitting diodes (WHLEDs) are considered as a solid approach toward environmentally sustainable lighting sources that meet the “Green Photonics” requirements. Here, WHLEDs with protein‐based down‐converting coatings, i.e., Bio‐WHLEDs, are demonstrated and exhibit worthy white color quality, luminous efficiency, and stability values. The coatings feature a multilayered cascade‐like architecture with thicknesses of 1–3 mm. This limits the efficiency due to the low optical transmittance. Thus, submillimeter coatings, where the location of the proteins is well‐defined, are highly desired. It is in this context where the thrust of this work sets in. Here, a straightforward way to design microstructured single‐layer coatings, in which the proteins are placed at our command by using 3D printing, is presented. Based on comprehensive spectroscopic and rheological investigations, the optimization of the matrix and the plotting to prepare different micropatterns, i.e., lines,...

Green Photonics" requirements, i.e., first-rate device performance, ecofriendly device fabrication, and recycling, as well as the use of nontoxic, low-cost, and abundant materials. [25-29] In general, the WHLED concept consists of a commercially available UV-or blue-LED, in which the encapsulating package is modified with an organic down-converting material that provides emission features in the low-energy region (Figure 1). Thus, this emerging hybrid technology combines the advantages of both inorganic and organic solid-state lighting devices, i.e., the excellent brightness and efficiency of high-energy emitting inorganic LEDs and the low-cost production and ease of color tunability of organic compounds. As such, this approach might circumvent important roadblocks, such as harsh and expensive fabrication conditions, the use of rare-Earth materials, as well as the need for multilayered architectures utilizing rigorous encapsulation systems due to the air-unstable nature of the electrodes and the charge injection layers. [30-34] The requirements of suitable down-converting materials for WHLEDs are (i) a good overlap between the LED excitation and the absorption peak of the luminescent compound, (ii) a high photoluminescence quantum yield and a broad emission band covering the entire visible spectrum, and (iii) a long-term

Glass slides (Corning, USA) were cleaned in piranha acid (7:3 v/v solution of H 2 SO 4 and H 2 O 2) for 30 min to increase their hydrophilicity and then rinsed thoroughly with Milli-Q water. Caution: piranha acid is a strong oxidizer and a strong acid. It should be handled with extreme care, as it reacts violently with most organic materials. Afterwards, they were mounted on ProPlate ® 4-well microarray system (Grace Bio-Labs, USA). Matrigel ™ (BD Biosciences) was thawed and diluted from 1/10 v/v to 1/40 v/v in DMEM (Gibco 11960, Spain), and gelatin from porcine skin (Sigma G2500, Spain) was dissolved in Milli-Q water at 56ºC from 0.05% to 0.5% w/v. The solutions were poured into predefined wells on the glass slides and, after the gelation process for 2 h at 37ºC, the excess of solution was removed. Matrigel ™ substrates were rinsed with 1X PBS and then with Milli-Q water. Subsequently, for the freeze-drying procedure, glass slides were immersed in liquid nitrogen and freeze-dried for 24 hours at-50ºC and 0.06 mbar of pressure (Christ Alpha 1-4 SC, SciQuip, UK). After freeze-drying, hydrogels were characterized by ultra-high resolution scanning electron microscopy (Nova™ NanoSEM 230, FEI Company, The Netherlands) working in low vacuum mode, at 0.5 mbar of water vapor pressure.

Bileaflet heart valves are currently the most commonly implanted type of mechanical prosthetic valve, because of their low transvalvular pressure drop, centralised flow and durability. However, in common with all mechanical heart valves, implanted bileaflet valves show an inherent tendency for blood clot formation at the valve site. Fluid dynamical phenomena associated with blood clotting are elevated blood shear stresses and regions of persistent blood recirculation, particularly when both occur together. Using three-dimensional CFD modelling, combined with enlarged scale experimental modelling, we investigated the blood flow through the ATS bileaflet valve during forward flow, with particular attention to the leaflet pivot regions. Recirculating regions were found both within and downstream of the valve housing ring. Qualitative assessment of the entire cardiac cycle suggested that recirculating blood within the housing ring will be washed away whilst the valve is closed, but as with all bileaflet valve designs recirculating blood downstream of the valve may have a residence time much longer than one cardiac cycle.

An overview is presented of the many ways in which batteries and battery materials are used in medicine and in biomedical studies. These include the use of batteries as power sources for motorised wheelchairs, surgical tools, cardiac pacemakers and defibrillators, dynamic prostheses, sensors and monitors for physiological parameters, neurostimulators, devices for pain relief, and iontophoretic, electroporative and related devices for drug administration. The various types of battery and fuel cell used for this wide range of applications will be considered, together with the potential harmful side effects, including accidental ingestion of batteries and the explosive nature of some of the early cardiac pacemaker battery systems.

A Stepper Motor Driven Reciprocating Pump (SDRP) can replace roller pumps and rotary pumps for cardio pulmonary bypass, hemodialysis and regional perfusion. The blood pumping ventricles are basically the same as ventricles used for air driven artificial hearts and ventricular assist devices. The electric stepper motor uses a flexible linkage belt to produce a reciprocating movement, which pushes a hard sphere into the diaphragm of the blood ventricles. The SDRP generates pulsatile flow and has a small priming volume. The preset power level of the motor driver limits the maximum potential outflow pressure, so the driver acts as a safety device. A double pump can be made by connecting two fluid pumping chambers to opposing sides of the motor base. Each pump generates pulsatile flow. Pressure and flow studies with water were undertaken. Preliminary blood studies showed low hemolysis, even when circulating a small amount of blood up to 16 hours.

Recent advances in the orthopedic prostheses design have significantly improved the quality of life for individuals with orthopedic disabilities. However, there are still critical challenges that need to be addressed to further enhance the functionality of orthopedic prostheses improving biocompatibility to promote better integration with natural tissues, enhancing durability to withstand the demands of daily use, and improving sensory feedback for better control of movement are the most pressing issues. To address these challenges, promising emerging solutions such as smart prosthetics, 3D printing, regenerative medicine, and artificial intelligence have been developed. These innovative technologies hold the potential to significantly enhance the functionality of orthopedic prostheses. Realizing the full potential of these next-generation orthopedic prostheses requires addressing several critical factors. These include interdisciplinary collaboration between experts in orthopedics, materials science, biology, and engineering, increased investment in research and development, standardization of components to ensure quality and reliability, and improved access to prosthetics. A comprehensive review of these challenges and considerations for future orthopedic prosthesis design is s provided in this paper addressing the further advances to the field. By addressing these issues, we can continue to improve the lives of individuals with orthopedic disabilities and further enhance the field of orthopedic prosthetics.

Since 1990, development of the Helmholtz-Institute at Aachen ventricular assist device (HIA-VAD) was mainly based on animal tests performed at the University of Groningen. Although various in vitro tests had been performed previously, animal testing resulted in significant improvements of the HIA-VAD with regard to hemodynamics and pump handling. The most important design improvement was a new trileaflet polyurethane valve, which was designed as a blood-pump valve with an emphasis on opening behavior and flow resistance. Excellent hydrodynamic performance and sufficient durability of this new valve were confirmed by various in vitro tests. Further design and manufacturing improvements resulted in a completely transparent pump, which can be easily deaired and optically controlled. Final pump design was evaluated during subsequent animal tests, and the results are very promising in view of an efficient cardiac support system.

In a properly contracting cardiac muscle, many different subcellular structures are organized into an intricate architecture. While it has been observed that this organization is altered in pathological conditions, the relationship between length-scales and architecture has not been properly explored. In this work, we utilize a variety of architecture metrics to quantify organization and consistency of single structures over multiple scales, from subcellular to tissue scale as well as correlation of organization of multiple structures. Specifically, as the best way to characterize cardiac tissues, we chose the orientational and co-orientational order parameters (COOPs). Similarly, neonatal rat ventricular myocytes were selected for their consistent architectural behavior. The engineered cells and tissues were stained for four architectural structures: actin, tubulin, sarcomeric z-lines, and nuclei. We applied the orientational metrics to cardiac cells of various shapes, isotropic ca...

The heart is a complex organ whose structure and function are intricately linked at multiple length scales. Although several advancements have been achieved in the field of cardiac tissue engineering, current in vitro cardiac tissues do not fully replicate the structure or function necessary for effective cardiac therapy and cardiotoxicity studies. This is partially due to a deficiency in current understandings of cardiac tissue organization's potential downstream effects, such as changes in gene expression levels. We developed a novel (to our knowledge) in vitro tool that can be used to decouple and quantify the contribution of organization and associated downstream effects to tissue function. To do so, cardiac tissue monolayers were designed into a parquet pattern to be organized anisotropically on a local scale, within a parquet tile, and with any desired organization on a global scale. We hypothesized that if the downstream effects were muted, the relationship between develo...

We thank the Ministry of Science and Technology of the Korean Government for supporting this work through the Creative Research Initiatives Program. Scheme 1. The procedures for patterning covalently bound monolayers of ZSM-5 crystals (I and II) and continuous ZSM-5 films (III).

The wearable artificial kidney (WAK) is a device that is supposed to operate like a real kidney, which permits prolonged, frequent, and continuous dialysis treatments for patients with end-stage renal disease (ESRD). Its functioning is mainly related to its pumping system, as well as to its dialysate-generating and alarm/shutoff ones. A pump is defined as a device that moves fluids by mechanical action. In such a context, blood pumps pull blood from the access side of the dialysis catheter and return the blood at the same rate of flow. The main aim of this paper is to review the current literature on blood pumps, describing the way they have been functioning thus far and how they are being engineered, giving details about the most important parameters that define their quality, thus allowing the production of a radar comparative graph, and listing ideal pumps' features.

Chronic renal failure and hemodialysis affect many ECG parameters which can affect cardiac repolarization. To investigate the change in ventricular repolarization before and after kidney transplantation in children. A total of 45 children with end-stage renal disease, 45 children at least 6 months after successful renal transplantation, and 45 normal age-matched subjects were enrolled into this study. A 12-lead ECG was recorded in the 3 groups. QT dispersion, QTc dispersion, and T peak to T end (TPE) dispersion were measured. In the patients before and after renal transplantation and the normal children, respectively, the mean±SD QT dispersion was 0.083±0.033, 0.056±0.029, and 0.033±0.016 (p<0.01); the mean±SD QTc dispersion was 0.104±0.038, 0.066±0.033, and 0.039±0.020 (p<0.01); the mean±SD TPE interval dispersion was 0.060±0.021, 0.045±0.021, and 0.034±0.019 (p<0.01). There was a significant correlation between left intra-ventricular diastolic diameter and QT dispersion, ...

Perhaps most dramatic of all, research efforts are now being directed towards the development of an artificial heart to replace a diseased heart.. .. This challenge-as exciting as any across the entire range of science-is enormously complex.. .. The goal is feasible; the problems are not insuperable."' Artificial hearts inside the chests of animals, replacing the natural heart, have been developed at the Cleveland Clinic since 1957. 2 Currently, an artificial heart has been made that fits inside the pericardial sac of a calf. Thus, it does not encroach upon the space normally occupied by the lungs. Calves were selected because the size of the heart required is the same as in the adult human, and also because the problems with thrombosis are perhaps less difficult than in dogs. It would be of great importance if more investigators would enter the field. Basic surgical experiments can be done and much useful experience can be obtained with the use of equipment developed earlier in our laboratory and now made available to other investigators through the National Heart Institute.** It is not implied that this equipment is perfect, or ready for clinical use. This paper, however, will show that it can be used in calves. We hope that other investigators will help to improve it. Total replacement of the natural hearts of calves was accomplished with two different artificial hearts and three different driving systems. The following three combinations were used. 1. Composite heart, handmade, driven by the servomechanism developed for us by the National Aeronautics and Space Administration (NASA), Lewis Research Center. 3 2. Composite heart, handmade, driven by an air-valve mechanism developed at the Cleveland Clinic and made by the Detroit Coil Corporation.ft *Fellow in the Department of Artificial Organs. \Research associate, Department of Artificial Organs. %Formerly consultant electronic engineer, Department of Artificial Organs. §.Special Fellow, Department of Artificial Organs. **The National Heart Institute has given contracts to industry so that Silastic hearts to be used inside the chest, and driving mechanisms to drive these hearts, could be produced. This is the first time that such an attempt has been made to get more investigators interested in these problems. Dr. Frank W. Hastings of the

Email: drkjs68@yahoo.com, drkjs68@gmail.com Jaishankar Krishnamoorthy, Ranjeet Palkar, Rashmi Maharajan, Latchumanadhas Kalidoss, Rajan Sethuratnam and Mullasari Ajit bioprosthetic tricupsid valve (BTV) using a 25mm Carpentier Edward Perimount valve. Also, the epicardial lead threshold was found to be greater than 5 Volts with end of life of pacemaker. Hence it was decided to implant an endocardial lead across the BTV. This lead was screwed onto the mid septum to ensure stability (Figure1a, b) and was connected to a pulse generator (Medtronic Sigma VVIR mode). The lead threshold and resistance were 0.7 Volts and 464 Ohms respectively. Post procedure echocardiography revealed normally functioning BTV with no regurgitation. Following this there was a dramatic improvement in heart function over the next few days. She was discharged after one more week of medical stabilisation with optimal pharmacotherapy. She has been asymptomatic during follow up at 1 and 3 months with no features of ...

A 37-year-old woman was admitted having suffered progressive swelling in her face, feet and abdomen for 3 months. On examination, she displayed features of right heart failure and was instituted on optimal pharmacotherapy with Diuretics, Digoxin, ACE inhibitors and Beta blockers. However, she continued to remain in a fluid overloaded state.

Email: drkjs68@yahoo.com, drkjs68@gmail.com Jaishankar Krishnamoorthy, Ranjeet Palkar, Rashmi Maharajan, Latchumanadhas Kalidoss, Rajan Sethuratnam and Mullasari Ajit bioprosthetic tricupsid valve (BTV) using a 25mm Carpentier Edward Perimount valve. Also, the epicardial lead threshold was found to be greater than 5 Volts with end of life of pacemaker. Hence it was decided to implant an endocardial lead across the BTV. This lead was screwed onto the mid septum to ensure stability (Figure1a, b) and was connected to a pulse generator (Medtronic Sigma VVIR mode). The lead threshold and resistance were 0.7 Volts and 464 Ohms respectively. Post procedure echocardiography revealed normally functioning BTV with no regurgitation. Following this there was a dramatic improvement in heart function over the next few days. She was discharged after one more week of medical stabilisation with optimal pharmacotherapy. She has been asymptomatic during follow up at 1 and 3 months with no features of ...

A 37-year-old woman was admitted having suffered progressive swelling in her face, feet and abdomen for 3 months. On examination, she displayed features of right heart failure and was instituted on optimal pharmacotherapy with Diuretics, Digoxin, ACE inhibitors and Beta blockers. However, she continued to remain in a fluid overloaded state.

Pioneering research suggests various modes of cellular therapeutics and biomaterial strategies for myocardial tissue engineering. Despite several advantages, such as safety and improved function, the dynamic myocardial microenvironment prevents peripherally or locally administered therapeutic cells from homing and integrating of biomaterial constructs with the infarcted heart. The myocardial microenvironment is highly sensitive due to the nanoscale cues that it exerts to control bioactivities, such as cell migration, proliferation, differentiation, and angiogenesis. Nanoscale control of cardiac function has not been extensively analyzed in the fi eld of myocardial tissue engineering. Inspired by microscopic analysis of the ventricular organization in native tissue, a scalable in-vitro model of nanoscale poly(L-lactic acid)-co-poly(ε-caprolactone)/collagen biocomposite scaffold is fabricated, with nanofi bers in the order of 594 ± 56 nm to mimic the native myocardial environment for freshly isolated cardiomyocytes from rabbit heart, and the specifi cally underlying extracellular matrix architecture: this is done to address the specifi city of the underlying matrix in overcoming challenges faced by cellular therapeutics. Guided by nanoscale mechanical cues provided by the underlying random nanofi brous scaffold, the tissue constructs display anisotropic rearrangement of cells, characteristic of the native cardiac tissue. Surprisingly, cell morphology, growth, and expression of an interactive healthy cardiac cell population are exquisitely sensitive to differences in the composition of nanoscale scaffolds. It is shown that suitable cell-material interactions on the nanoscale can stipulate organization on the tissue level and yield novel insights into cell therapeutic science, while providing materials for tissue regeneration.

Pacemakers are extensively used in treating patients with cardiac arrhythmia. These devices are compact and operate by sending electrical impulses to the heart muscles, making them contract and pump blood. People with irregular heartbeats can lead a normal lifestyle after they have pacemakers implanted. Several important aspects of the heart, heart anatomy, cardiac cycle and information about pacemakers are presented.

Pacemaker lead extraction is the treatment of choice in infectious complications regarding implantation procedure. The purpose of this study was to estimate the safety of the extraction in relation to the morphological changes of the pacing electrode. Research was carried out on materials consisting of 60 human hearts from 45 to 95 years of age (average 63 +/- 15 yrs), with VVI or DDD pacing (pacing duration 84 +/- 26 months) fixed in a formalin solution. Classical macroscopic anatomical methods were applied. In 44 hearts (73.3%) from the investigated group the posterior tricuspid leaflet was thickened only, and in 24 of these hearts the process regarded not only posterior leaflet but also the septal one and especially commissure between them. In 52 hearts (86.6%) inflammatory reaction spread also to the neighbouring part of the electrode. The length of the neointima-inflammatory tissue ranged from 4 to 8 mm (average 5 +/- 2 mm). On the tip of the electrode in the right ventricle ca...

Flow visualization is typically applied in blood pump development to both confirm the design expectations and identify regions that may be predisposed to blood element deposition and trauma. Rotary pumps, in particular, place high demands on the technique chosen to visualize the flow given the limited visual accessibility of the flow path and the high impeller speeds. Fluorescent image-tracking velocimetry currently is used at the University of Pittsburgh Medical Center to visualize flow accurately inside of these pumps both qualitatively and quantitatively. Flow patterns under steady conditions within an intraventricular axial flow, left ventricular assist pump (prototype No. 7, SUN Medical Technology Research Corporation, Nagano, Japan) were investigated using this technique. The flow fields at the impeller-stator interface and at the pump outlet were given specific attention. This allowed the assessment of the fluid dynamics throughout the hydrodynamic design limits of the pump.

Abstract: This study shows a method than can be used to determine the best angular position of heart valves installed at the inlet and the outlet of a blood chamber during the diastolic phase with use of Computational Fluid Dynamics (CFD). Steady state simulations of the blood flow through the blood chamber of Pediatric Ventricular Assist Device (PVAD) have been performed with ANSYS CFX 14.0. Main assumptions in the present paper have included: motionless discs, rigid walls, non-Newtonian model of blood. The obtained results show that areas of blood stagnation in the blood chamber are smallest for one particular angular position of the inlet valve and are not significantly dependent on the angular position of the outlet valve.

Bileaflet heart valves are currently the most commonly implanted type of mechanical prosthetic valve, because of their low transvalvular pressure drop, centralised flow and durability. However, in common with all mechanical heart valves, implanted bileaflet valves show an inherent tendency for blood clot formation at the valve site. Fluid dynamical phenomena associated with blood clotting are elevated blood shear stresses and regions of persistent blood recirculation, particularly when both occur together. Using three-dimensional CFD modelling, combined with enlarged scale experimental modelling, we investigated the blood flow through the ATS bileaflet valve during forward flow, with particular attention to the leaflet pivot regions. Recirculating regions were found both within and downstream of the valve housing ring. Qualitative assessment of the entire cardiac cycle suggested that recirculating blood within the housing ring will be washed away whilst the valve is closed, but as w...

The use of cardiopulmonary bypass (CPB) is extending out of the cardiac surgery operating room into new venues. The long-term goal of this project is the development of a completely disposable temporary-use CPB system that could be economically distributed to all of the units where it might be needed. Centrifugal blood pumps have demonstrated successful and widespread use. However, they are not as widely available as might be desired because they require a large and expensive console. An inexpensive, small, lightweight, disposable unit, in contrast, could be widely distributed for ernergency care of patients and would be logistically practical for patient transportation between the presenting institution and a major cardiac care facility equipped for definitive treatment. An air motor might be an approach to such a device. The current research project underway at the University of Akron in conjunction with the Cleveland Clinic Foundation has focused on the following key feasibility issues: air consumption, air motor noise, and sealing the rotating shaft. Prototypes have been constructed from commercially available vane and turbine motors. Early studies have demonstrated favorable results with regard to air consumption and shaft sealing and directions for handling air motor noise.

We report on a 51-year old heart transplant recipient in whom a pacing lead fragment of his old implantable cardioverter-defibrillator (ICD) had been detected in the left ventricle following successful heart transplantation. The patient was transplanted after 5 weeks on high urgent status. A postoperative routine chest X-ray and a subsequent cardiac three-dimensional (3D) computed tomography scan showed a metallic foreign body bending during systole below the posterior mitral valve leaflet within the left ventricle of the heart transplant. Transarterial extraction therapy was planned and the femoral artery was cannulated in the usual fashion. An 8F snare catheter was directed into the left ventricle under fluoroscopic guidance. Successful extraction revealed a 3-cm, uncoated ICD fragment (diameter = 0.025 in.). Following extraction of the fragment echocardiography showed mild mitral regurgitation but no further adverse events occurred. The patient was discharged 2 days later. Transa...

Traction force microscopy (TFM) is the main method used in mechanobiology to measure cell forces. Commonly this is being used for cells adhering to flat soft substrates that deform under cell traction (2D-TFM). TFM relies on the use of linear elastic materials, such as polydimethylsiloxane (PDMS) or polyacrylamide (PA). For 2D-TFM on PA, the difficulty in achieving high throughput results mainly from the large variability of cell shapes and tractions, calling for standardization. We present a protocol to rapidly and efficiently fabricate micropatterned PA hydrogels for 2D-TFM studies. The micropatterns are first created by maskless photolithography using near-UV light where extracellular matrix proteins bind only to the micropatterned regions, while the rest of the surface remains non-adhesive for cells. The micropatterning of extracellular matrix proteins is due to the presence of active aldehyde groups, resulting in adhesive regions of different shapes to accommodate either single cells or groups of cells. For TFM measurements, we use PA hydrogels of different elasticity by varying the amounts of acrylamide and bis-acrylamide and tracking the displacement of embedded fluorescent beads to reconstruct cell traction fields with regularized Fourier Transform Traction Cytometry (FTTC). To further achieve precise recording of cell forces, we describe the use of a controlled dose of patterned light to release cell tractions in defined regions for single cells or groups of cells. We call this method local UV illumination traction force microscopy (LUVI-TFM). With enzymatic treatment, all cells are detached from the sample simultaneously, whereas with LUVI-TFM traction forces of cells in different regions of the sample can be recorded in sequence. We demonstrate the applicability of this protocol (i) to study cell traction forces as a function of controlled adhesion to the

The formation of thrombi on the streamlined surface of the bileaflet mechanical heart valves is one of the main disadvantages of such valves. Thrombi block the valve leaflets and disrupt the cardiovascular system. Diagnosis of thrombosis of the bileaflet mechanical heart valves is relevant and requires the creation of effective diagnostic tools. Hydroacoustic registration of the heart noise is one of the methods for diagnosing the operation of a mechanical heart valve. The purpose of the research is to determine the statistical characteristics of the vortex and jet flow through the open and semi-closed bileaflet mechanical heart valve, to identify hydroacoustic differences and diagnostic signs to determine the operating conditions of the valve. Experimental studies were conducted in laboratory conditions on a model of the left atrium and left ventricle of the heart between which there was the bileaflet mechanical heart valve. Hydrodynamic noise was recorded by miniature pressure sen...

Microphysiological systems and organs-on-chips promise to accelerate biomedical and pharmaceutical research by providing accurate in vitro replicas of human tissue. Aside from addressing the physiological accuracy of the model tissues, there is a pressing need for improving the throughput of these platforms. To do so, scalable data acquisition strategies must be introduced. To this end, we here present an instrumented 24-well plate platform for higher-throughput studies of engineered human stem cell-derived cardiac muscle tissues that recapitulate the laminar structure of the native ventricle. In each well of the platform, an embedded flexible strain gauge provides continuous and non-invasive readout of the contractile stress and beat rate of an engineered cardiac tissue. The sensors are based on micro-cracked titanium-gold thin films, which ensure that the sensors are highly compliant and robust. We demonstrate the value of the platform for toxicology and drug-testing purposes by p...

Cardiac tissue development and pathology have been shown to depend sensitively on microenvironmental mechanical factors, such as extracellular matrix stiffness, in both in vivo and in vitro systems. We present a novel quantitative approach to assess cardiac structure and function by extending the classical traction force microscopy technique to tissue-level preparations. Using this system, we investigated the relationship between contractile proficiency and metabolism in neonate rat ventricular myocytes (NRVM) cultured on gels with stiffness mimicking soft immature (1 kPa), normal healthy (13 kPa), and stiff diseased (90 kPa) cardiac microenvironments. We found that tissues engineered on the softest gels generated the least amount of stress and had the smallest work output. Conversely, cardiomyocytes in tissues engineered on healthy-and disease-mimicking gels generated significantly higher stresses, with the maximal contractile work measured in NRVM engineered on gels of normal stiffness. Interestingly, although tissues on soft gels exhibited poor stress generation and work production, their basal metabolic respiration rate was significantly more elevated than in other groups, suggesting a highly ineffective coupling between energy production and contractile work output. Our novel platform can thus be utilized to quantitatively assess the mechanotransduction pathways that initiate tissue-level structural and functional remodeling in response to substrate stiffness.

Humans are blessed with a wide variety of fruits and vegetables by the nature. Fruits and vegetables are significant sources of several vitamins and minerals that play vital role for the maintenance of good health. The manuscript provides a useful overview of the beneficial effects of fruits and vegetables, and their vitamins content that support the immune system. It discusses fat and water-soluble vitamins in fruits and vegetables with outstanding care and their role in maintaining the body's balance, preventing disease such as malnutrition and in adjunctive therapy. Among the fruits and vegetables that can be considered as functional foods because of their useful physiological effect, the most important content evaluation of the grapes, apples, bananas, carrots, beetroots, onions, and lemons is the main goal of the manuscript. These fruits and vegetables were selected for their useful components and their role in international gastronomy, among others. We hope to contribute to both the knowledge of readers and the protection of their health.

The formation of thrombi on the streamlined surface of the bileaflet mechanical heart valves is one of the main disadvantages of such valves. Thrombi block the valve leaflets and disrupt the cardiovascular system. Diagnosis of thrombosis of the bileaflet mechanical heart valves is relevant and requires the creation of effective diagnostic tools. Hydroacoustic registration of the heart noise is one of the methods for diagnosing the operation of a mechanical heart valve. The purpose of the research is to determine the statistical characteristics of the vortex and jet flow through the open and semi-closed bileaflet mechanical heart valve, to identify hydroacoustic differences and diagnostic signs to determine the operating conditions of the valve. Experimental studies were conducted in laboratory conditions on a model of the left atrium and left ventricle of the heart between which there was the bileaflet mechanical heart valve. Hydrodynamic noise was recorded by miniature pressure sen...