Direct flow valve

Central lymphatic diseases such as intractable chylothorax can be fatal. Lymphatic venous anastomosis at the venous angle level is expected to give a direct therapeutic effect because it opens the obstructed outlet of the main lymphatic vessels. However, the original methods resulted in some important issues, such as the potential for venous reflux. In the present case, we modified the original anastomosis method by interposing a vein graft with venous valves to increase the distance and prevent venous reflux...

BACKGROUND: The rotational direction (RD) of helical blood flow can be classified as either a clockwise (RD+ ) or counter-clockwise (RD- ) flow. We hypothesized that this simple classification might not be sufficient for analysis in vivo and a simultaneous existence of RD+/- may occur. We utilized volumetric velocity-sensitive cardiovascular magnetic resonance imaging (4D flow MRI) to analyze rotational blood flow in the thoracic aorta. METHODS: Forty volunteers (22 females; mean age, 41±16 years) and seventeen patients with bicuspid aortic valves (BAVs) (9 females; mean age, 42±14 years) were prospectively included...

BACKGROUND: In patients at urgent need for cardiac surgery coexisting with increased-stroke-risk carotid stenosis, any staged intervention increases the risk of complications from the primarily unaddressed pathology. In this challenging cohort, we assessed safety and feasibility of endovascular carotid revascularization under open-chest extracorporeal circulation (ECC) combined with cardiac surgery (hybrid-room true simultaneous treatment). METHODS: Per-protocol (PP), after general anesthesia induction, chest-opening and ECC stand-by installation, carotid stenting (CAS) was performed (femoral/radial or direct carotid access) with ad-hoc/on-hand switch to ECC cardiac surgery...

"Aortic stenosis" (AS) refers to a cardiac condition in which the aortic valve narrows, creating an obstruction that hinders the flow of blood from the left ventricle to the aorta. This contraction of the arteries influences normal blood circulation, leading to elevated pressure within the left ventricle and potentially culminating in heart failure. The management of AS typically involves two primary treatments, i.e. "surgical aortic valve replacement" (SAVR) and "transcatheter aortic valve replacement" (TAVR)...

Aortic valve stenosis (AS) is increasing in prevalence due to the aging population, and severe AS is associated with significant morbidity and mortality. Echocardiography remains the mainstay for the initial detection and diagnosis of AS, as well as for grading of severity. However, there are important subgroups of patients, for example, patients with low-flow low-gradient or paradoxical low-gradient AS, where quantification of severity of AS is challenging by echocardiography and underestimation of severity may delay appropriate management and impart a worse prognosis...

Current guidelines of aortic stenosis (AS) management focus on valve parameters, LV systolic dysfunction, and symptoms; however, emerging data suggest that there may be benefit of aortic valve replacement before it becomes severe by present criteria. Myocardial assessment using novel multimodality imaging techniques exhibits subclinical myocardial injury and remodeling at various stages before guideline-directed interventions, which predicts adverse outcomes. This raises the question of whether implementing serial myocardial assessment should become part of the standard appraisal, thereby identifying high-risk patients aiming to minimize adverse outcomes...

UNLABELLED: We present the results of a combined approach for transapical aortic valve replacement and minimally invasive coronary artery bypass grafting (taTAVI-MIDCAB) in patients with combined aortic stenosis and coronary artery disease. BACKGROUND: For patients presenting with aortic stenosis and coronary artery disease, a simultaneous procedure addressing both diseases is recommended to reduce operative risk. In high-risk patients with hostile femoral or coronary axis, taTAVI-MIDCAB can be an alternative minimally invasive approach, offering the benefits of left interior mammary artery to left anterior descending coronary artery (LIMA-LAD) grafting...

Simultaneous ventilation of two patients may lead to hypoventilation in one patient and hyperinflation in the other patient. In a simulation of ventilation in two patients using artificial lungs, we voluntarily directed gas flow to one patient by using three-dimensional-printed Y-adapters and stenosis adapters during volume- and pressure-controlled ventilation in the first set up. We continuously modified the model using a special one-way valve on the flow-limited side and measured it in pressure-controlled ventilation with the flow sensor of the ventilator adjusted on both sides in a second and third setup...

Herein, we provide evidence that human regulation of aqueous outflow is by a pump-conduit system similar to that of the lymphatics. Direct observation documents pulsatile aqueous flow into Schlemm's canal and from the canal into collector channels, intrascleral channels, aqueous veins, and episcleral veins. Pulsatile flow in vessels requires a driving force, a chamber with mobile walls and valves. We demonstrate that the trabecular meshwork acts as a deformable, mobile wall of a chamber: Schlemm's canal. A tight linkage between the driving force of intraocular pressure and meshwork deformation causes tissue responses in milliseconds...

Heart failure is a global health concern with significant implications for healthcare systems. Left ventricular assist devices (LVADs) provide mechanical support for patients with severe heart failure. However, the placement of the LVAD outflow graft within the aorta has substantial implications for hemodynamics and can lead to aortic insufficiency during long-term support. This study employs computational fluid dynamics (CFD) simulations to investigate the impact of different LVAD outflow graft locations on aortic hemodynamics...

Biological parameters extracted from electrical signals from various body parts have been used for many years to analyze the human body and its behavior. In addition, electrical signals from cancer cell lines, normal cells, and viruses, among others, have been widely used for the detection of various diseases. Single-cell parameters such as cell and cytoplasmic conductivity, relaxation frequency, and membrane capacitance are important. There are many techniques available to characterize biomaterials, such as nanotechnology, microstrip cavity resonance measurement, etc...

There is a contradiction between the calculation accuracy and cost when computing the pressure and flow rate. A throttling characteristics prediction methodology for directional spool valve was proposed to balance the contradiction. The throttling characteristics were represented by the flow-number, defined as the product of the flow coefficient and the orifice area, to reveal simultaneously the mapping relationships of the two versus the spool geometry, stroke and flow rate. The pressure and flow rate characteristics at different strokes were obtained through the computational fluid dynamic (CFD) simulations that were validated through bench testing...

INTRODUCTION: Transcatheter aortic valve intervention (TAVR) has emerged as a promising alternative to surgical aortic valve replacement for patients with severe aortic stenosis. However, leaflet thrombosis has raised concerns about the long-term durability and outcomes of TAVR. This study aims to provide an overview of the mechanisms, prevention strategies, and treatment options for leaflet thrombosis in TAVR. CLINICAL EVIDENCE: Leaflet thrombosis refers to the formation of blood clots on bioprosthetic valve leaflets, leading to impaired leaflet mobility, early valve degeneration and dysfunction, and potential clinical implications...

Lab-on-a-disc (LoaD) technology has emerged as a transformative approach for point-of-care diagnostics and high-throughput testing. The promise of integrating multiple laboratory functions onto a single integrated platform has significant implications for healthcare, especially in resource-limited settings. However, one of the primary challenges faced in the design and manufacture of LoaD devices is the integration of effective valving mechanisms. These valves are essential for fluid control and routing, but their intricacy often leads to complexities in design and increased vulnerability to failure...

BACKGROUND AND OBJECTIVES: Coronary obstruction is a complication that may affect patients receiving Transcatheter Aortic Valve Replacement (TAVR), with catastrophic consequences and long-term negative effects. To enable healthy coronary perfusion, it is fundamental to appropriately position the device with respect to the coronary ostia. Nonetheless, most TAVR delivery systems do not control commissural alignment to do so. Moreover, no in silico study has directly assessed the effect of commissural alignment on coronary perfusion...

Respiratory dysfunction often decreases arterial oxygen content. Four common oxygen delivery techniques-flow-by, nasal prongs, a tight-vented mask, and a tight mask connected to a Venturi valve-were evaluated for their effectiveness in increasing the oxygen reserve index (ORi), a dimensionless index of oxygen content that provides additional information compared to traditional pulse oximetry (SpO2 ) during hyperoxia (PaO2 100-200 mmHg), and that ranges from 0 to 1. Thirty-two dogs sedated with dexmedetomidine and an opioid were evenly divided into four groups based on the technique for oxygen administration...

Blood flow in large veins is dependent on arterial-atrial pressure gradients and pumping mechanisms in concert with valve recruitment. Classic descriptions of muscle and respiratory pumps describe venous transmural pressure changes that cause flow. Not often considered is the transmission of pulsatile energy from arteries to veins directly adjacent to each other. Recently, an ex vivo study demonstrated a novel arterial pump effect in veno-arterial bundles when valves were active in managing venous flow. We sought to show in vivo evidence of this arterial pump mechanism in 16 healthy, young adults...

Maternal hyperoxygenation (MH) has been studied as a diagnostic tool to evaluate pulmonary vasculature and as a treatment option to improve the growth of fetal left heart in fetuses with left-sided cardiac defects. Chronic maternal hyperoxygenation (CMH) therapy leads to an improvement in fetal pulmonary blood flow resulting in an enhanced venous return to the left heart with increased gestational age. With this manipulation it is anticipated to augment blood flow directed remodeling of the left heart structures and to improve left heart growth spanning from the mitral valve to the aortic isthmus...

This note describes the development and testing of a novel, programmable reversing flow 1D (R1D) experimental column apparatus designed to investigate reaction, sorption, and transport of solutes in aquifers within dynamic reversing flow zones where waters with different chemistries mix. The motivation for constructing this apparatus was to understand the roles of mixing and reaction on arsenic discharging through a tidally fluctuating riverbank. The apparatus can simulate complex transient flux schedules similar to natural flow regimes The apparatus uses an Arduino microcontroller to control flux magnitude through two peristaltic pumps...

BACKGROUND: Lymphatic valves play a critical role in ensuring unidirectional lymph transport. Loss of lymphatic valves or dysfunctional valves are associated with several diseases including lymphedema, lymphatic malformations, obesity, and ileitis. Lymphatic valves first develop during embryogenesis in response to mechanotransduction signaling pathways triggered by oscillatory lymph flow. In blood vessels, eNOS (endothelial NO synthase; gene name: Nos3 ) is a well-characterized shear stress signaling effector, but its role in lymphatic valve development remains unexplored...