SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Valve

150

Transcatheter interventions with balloon-expandable valves have been shown to be efficacious for the treatment of mitral annuloplasty failure but are limited by the fact that there is no opportunity for post-implantation adjustment. The aim of this study was to assess the safety and efficacy of the fully repositionable and retrievable Direct Flow Medical (DFM) valve for the treatment of mitral annuloplasty failure.

Concepts: Valve, Artificial heart valve, Left ventricle, Mitral valve repair, Aortic valve

56

Limited information is available regarding genetic contributions to valvular calcification, which is an important precursor of clinical valve disease.

Concepts: Check valve, Valve

31

The creation of a living heart valve is a much-wanted alternative for current valve prostheses that suffer from limited durability and thromboembolic complications. Current strategies to create such valves, however, require the use of cells for in vitro culture, or decellularized human- or animal-derived donor tissue for in situ engineering. Here, we propose and demonstrate proof-of-concept of in situ heart valve tissue engineering using a synthetic approach, in which a cell-free, slow degrading elastomeric valvular implant is populated by endogenous cells to form new valvular tissue inside the heart. We designed a fibrous valvular scaffold, fabricated from a novel supramolecular elastomer, that enables endogenous cells to enter and produce matrix. Orthotopic implantations as pulmonary valve in sheep demonstrated sustained functionality up to 12 months, while the implant was gradually replaced by a layered collagen and elastic matrix in pace with cell-driven polymer resorption. Our results offer new perspectives for endogenous heart valve replacement starting from a readily-available synthetic graft that is compatible with surgical and transcatheter implantation procedures.

Concepts: Valvular heart disease, Surgery, Ball valve, Polymer, Check valve, Implantation, Valve, Valves

28

Reoperation for failing stentless aortic valve replacement is a technically demanding procedure that has traditionally been tackled in one of two ways: either root replacement or the more conservative option of implanting a stented valve within the valve. We sought to determine the relative operative risks, follow-up status and medium to long-term survival of these two methods.

Concepts: Valve Corporation, Valve, Derivative, Left ventricle, Aortic insufficiency, Aortic valve replacement, Aortic valve

28

Object Overdrainage of CSF remains an unsolved problem in shunt therapy. The aim of the present study was to evaluate treatment options on overdrainage-related events enabled by the new generation of adjustable gravity-assisted valves. Methods The authors retrospectively studied the clinical course of 250 consecutive adult patients with various etiologies of hydrocephalus after shunt insertion for different signs and symptoms of overdrainage. Primary and secondary overdrainage were differentiated. The authors correlated the incidence of overdrainage with etiology of hydrocephalus, opening valve pressure, and patient parameters such as weight and size. Depending on the severity of overdrainage, they elevated the opening pressure, and follow-up was performed until overdrainage was resolved. Results The authors found 39 cases (15.6%) involving overdrainage-related problems-23 primary and 16 secondary overdrainage. The median follow-up period in these 39 patients was 2.1 years. There was no correlation between the incidence of overdrainage and any of the following factors: sex, age, size, or weight of the patients. There was also no statistical significance among the different etiologies of hydrocephalus, with the exception of congenital hydrocephalus. All of the “complications” could be resolved by readjusting the opening pressure of the valve in one or multiple steps, avoiding further operations. Conclusions Modern adjustable and gravity-assisted valves enable surgeons to set the opening pressure relatively low to avoid underdrainage without significantly raising the incidence of overdrainage and to treat overdrainage-related clinical and radiological complications without surgical intervention.

Concepts: Valve, Etiology, Medicine, Shunt, Surgery, Cerebrospinal fluid, Hydrocephalus

27

What happens to tap water when you are away from home? Day-to-day water stagnation in building plumbing can potentially result in water quality deterioration (e.g., lead release or pathogen proliferation), which is a major public health concern. However, little is known about the microbial ecosystem processes in plumbing systems, hindering the development of biological monitoring strategies. Here, we track tap water microbiome assembly in situ, showing that bacterial community composition changes rapidly from the city supply following ~6-day stagnation, along with an increase in cell count from 103cells/mL to upwards of 7.8 × 105cells/mL. Remarkably, bacterial community assembly was highly reproducible in this built environment system (median Spearman correlation between temporal replicates = 0.78). Using an island biogeography model, we show that neutral processes arising from the microbial communities in the city water supply (i.e., migration and demographic stochasticity) explained the island community composition in proximal pipes (Goodness-of-fit = 0.48), yet declined as water approached the faucet (Goodness-of-fit = 0.21). We developed a size-effect model to simulate this process, which indicated that pipe diameter drove these changes by mediating the kinetics of hypochlorite decay and cell detachment, affecting selection, migration, and demographic stochasticity. Our study challenges current water quality monitoring practice worldwide which ignore biological growth in plumbing, and suggests the island biogeography model as a useful framework to evaluate building water system quality.

Concepts: Tap water, Water supply, Valve, Bacteria, Water quality, Water supply network, Drinking water, Water

27

To test the ability of a model-based segmentation of the aortic root for consistent assessment of aortic valve structures in patients considered for transcatheter aortic valve implantation (TAVI) who underwent 256-slice cardiac computed tomography (CT).

Concepts: Aortic valve, Valve, Left ventricle, Radiography, Radiology, Aorta, Computed tomography angiography, Medical imaging

19

Endobronchial valves (EBV) have been successfully used in patients with severe heterogeneous emphysema to improve lung physiology. Limited available data suggests that EBVs are also effective in homogeneous emphysema.

Concepts: Valve Corporation, Valve, Lung

18

To evaluate whether differences in tap water and other beverage intake explain differences in inadequate hydration among US adults by race/ethnicity and income.

Concepts: Valve, Sociology

8

To reduce the possibility of secondary deterioration of spinal injuries, it is desirable to maintain the spinal immobilisation that is applied in the prehospital setting throughout computed tomography (CT) scanning. A previous study found that metallic components within the inflation valve of the vacuum mattresses caused CT artefacts. The aim of our study was to investigate the effect of vacuum mattresses with plastic valves on CT artefacts, the radiation dose, and noise compared to a trauma transfer board and the spine boards currently used in our trauma system.

Concepts: Aluminium, Valve Corporation, Board, Valve, The Spine, Emergency medicine, Ionizing radiation, Physical trauma