Transcatheter Therapy for Mitral Valve Stenosis.

Mitral valve stenosis remains highly prevalent among the US population although with dramatically shifting demographics. The significance of rheumatic mitral disease in developing nations persists, despite improvements in preventative measures and early detection, and its presence in developed countries is still evident as observed through international migration. In addition, the substantial growth in the aging population with a heightened occurrence of concurrent cardiovascular risk factors is leading to an increased prevalence of chronic calcific degeneration and degeneration of previously repaired or replaced valves. This article aims to review various transcatheter therapies in the treatment of mitral valve stenosis.

Dataset of process-structure-property feature relationships for AlSi10Mg material fabricated using laser powder bed fusion additive manufacturing.

This dataset reports microstructure and mechanical property features of AlSi10Mg manufactured using laser powder bed fusion over a wide range of processing conditions. Samples were fabricated with different combinations of laser power, scan speed, and hatch spacing to probe dense regimes as well as porous samples resulting from keyholing and lack of fusion. Pore and grain/sub-grain features for each processing set were quantified. Sample porosity was measured using Archimedes density measurements and X-ray computed tomography (XCT). XCT was also used to characterize the surface roughness of samples along with pore size and morphology. Electron backscatter diffraction (EBSD) was used to characterize the grain size and morphology while scanning electron microscope (SEM) imaging and was used to measure solidification cell size. Uniaxial tension tests were performed to ascertain yield and ultimate tensile strengths, elongation, and elastic modulus, and microhardness was measured using Vickers indentation.

Mitral Valve Transcatheter Edge-to-Edge Repair Volumes and Trends.

Background: Despite an association between operator volumes and procedural success, there remains an incomplete understanding of the contemporary utilization and procedural volumes for mitral valve transcatheter edge-to-edge repair (MTEER). We aimed to identify annual operator procedural volumes, temporal trends, and geographic variability for MTEER among Medicare patients in the United States (US). Methods: We queried the National Medicare Provider Utilization and Payment Database for a CPT code (33418) specific for MitraClip device from 2015 through 2019. We analyzed annual operator procedural volumes and incidence and identified longitudinal and geographic trends in MTEER utilization. Results: From 2015 through 2019, a total of 27,034 MTEER procedures were performed among Medicare patients in the US. The nationwide incidence increased from 6.2 per 100,000 patients in 2015 to 23.8 per 100,000 patients in 2019, a 283% increase over the study period (Ptrend < 0.001). The incidence of MTEER by state varied by nearly 900% (range 5.5 to 54.9 per 100,000 person-years). In 2019, the mean annual MTEER operator annual volume was 9.1 MTEER procedures and had grown from 6.2 per year in 2015. Conclusions: In this nationwide study of Medicare beneficiaries in the United States, we identified a significant and sustained increase in the utilization of MTEER devices and operators and growth in annual procedural volumes from 2015 through 2019 with considerable variability in utilization by state. Further studies are needed to understand the clinical impact of variability in utilization and the optimal procedural volumes to ensure high efficacy outcomes and maintain critical access to MTEER therapies.

Catalog of triply periodic minimal surfaces, equation-based lattice structures, and their homogenized property data.

The use of lattice structure in the Design for Additive Manufacturing (DfAM) engineering practice offers the ability to tailor the properties (and therefore the response) of an engineered component independent of the material and overall geometry. The selection of a lattice topology is critical in maximizing the value of the lattice structure and its unique properties for the intended application. To support this, we have compiled a catalog of lattice structures from the literature that includes all Triply Periodic Minimal Surfaces (TPMS) for which a low-order Fourier series fit is known (so that they can be modeled and manufactured). We also include equations that do not directly correspond to known TPMS but do produce a triply periodic structure without sharp corners that would give rise to stress concentrations. This catalog includes images, elastic mechanical property data, and CAD models useful for the visualization, selection, and implementation of these lattice structures for any engineered structure.

Clinical Predictors of Mortality and Heart Failure Hospitalization in Patients With Severe Tricuspid Regurgitation.

Background: There is an incomplete understanding of the predictors of morbidity and mortality in patients with severe tricuspid regurgitation (TR). This study sought to identify key risk factors for all-cause mortality and heart failure (HF) hospitalization among patients with severe TR. Methods: Patients with severe TR were identified from 2 centers, Oregon Health & Science University and Abrazo Health, from January 01, 2016 to December 31, 2018. Patients with any concomitant severe valvular diseases or prior valvular intervention were excluded. Multivariable regression was utilized to identify demographic, clinical, and echocardiographic variables independently associated with all-cause mortality or HF hospitalization. Results: 435 patients with severe TR were followed for a median of 2.8 years. The mean age of the population was 66.9 ± 18.5 years and 58% were female. All-cause mortality was identified in 20.5% of the population. Of the cohort, 35.4% of patients were hospitalized for HF. Isolated tricuspid valve intervention was performed in 2.5% of patients. Independent predictors of all-cause mortality included history of solid tumor (odds ratio [OR] 6.6, 95% confidence interval [CI] 2.1-19.1, p = 0.001), history of peripheral artery disease (OR 3.5, 95% CI 1.2-9.4, p = 0.013), and elevated international normalized ratio in the absence of anticoagulation (OR 1.9, 95% CI 1.2-3.2, p = 0.008). Predictors of HF hospitalization included history of diabetes mellitus (OR 2.2, 95% CI 1.1-4.0, p = 0.014) and history of reduced left ventricular ejection fraction (OR 5.7, 95% CI 2.9-11.7, p < 0.0001). Conclusions: Severe untreated TR is associated with high mortality and frequent HF hospitalizations. Understanding predictors of these outcomes is important to identify patients who may benefit from early tricuspid valve intervention to help improve outcomes in this patient population.

Teaching Designing for Additive Manufacturing: Formulating Educational Interventions That Encourage Design Creativity.

As additive manufacturing (AM) processes become more ubiquitous in engineering, design, and manufacturing, the need for a workforce skilled in designing for additive manufacturing (DfAM) has grown. Despite this need for an AM-skilled workforce, little research has systematically investigated the formulation of educational interventions for training engineers in DfAM. In this article, we synthesize findings from our experiments with 596 engineering design students to inform the development of educational interventions-comprising content presentations and design tasks-that encourage student learning and creativity. Specifically, we investigated the effects of four variations of DfAM educational interventions by manipulating the following: (1) the content of DfAM information presented, (2) the order of presenting the DfAM content, (3) the definition of the AM design task, and (4) the competitive structure of the AM design task. The effects of these variations were experimentally tested by comparing changes in students' DfAM self-efficacy and the creativity of students' design outcomes. Validated measures were also developed as part of our studies to help mature the nascent field of DfAM education. Based on the findings of our experiments, we discuss how task-based educational interventions can be formulated to (1) increase students' DfAM self-efficacy, (2) encourage students to generate ideas of high AM technical goodness, and (3) encourage students to generate more creative ideas when using AM. The novel synthesis of our findings in this article will help educators formulate effective DfAM educational interventions and tasks to foster a workforce skilled in DfAM.

Is Additive Manufacturing an Environmentally and Economically Preferred Alternative for Mass Production?

The manufacturing sector accounts for a large percentage of global energy use and greenhouse gas emissions, and there is growing interest in the potential of additive manufacturing (AM) to reduce the sector's environmental impacts. Across multiple industries, AM has been used to reduce material use in final parts by 35-80%, and recent publications have predicted that AM will enable the fabrication of customized products locally and on-demand, reducing shipping and material waste. In many contexts, however, AM is not a viable alternative to traditional manufacturing methods due to its high production costs. And in high-volume mass production, AM can lead to increased energy use and material waste, worsening environmental impacts compared to traditional production methods. Whether AM is an environmentally and economically preferred alternative to traditional manufacturing depends on several hidden aspects of AM that are not readily apparent when comparing final products, including energy-intensive and expensive material feedstocks, excessive material waste during production, high machine costs, and slow rates of production. We systematically review comparative studies of the environmental impacts and costs of AM in contrast with traditional manufacturing methods and identify the conditions under which AM is the environmentally and economically preferred alternative. We find that AM has lower production costs and environmental impacts when production volumes are relatively low (below ∼1,000 per year for environmental impacts and below 42-87,000 per year for costs, depending on the AM process and part geometry) or the parts are small and would have high material waste if traditionally manufactured. In cases when the geometric freedom of AM enables performance improvements that reduce environmental impacts and costs during a product's use phase, these can counteract the higher production impacts of AM, making it the preferred alternative at larger production volumes. AM's ability to be environmentally and economically beneficial for mass manufacturing in a wider variety of contexts is dependent on reducing the cost and energy intensity of material feedstock production, eliminating the need for support structures, raising production speeds, and reducing per unit machine costs. These challenges are not primarily caused by economies of scale, and therefore, they are not likely to be addressed by the increasing expansion of the AM sector. Instead, they will require fundamental advances in material science, AM production technologies, and computer-aided design software.

Dataset of process-structure-property feature relationship for laser powder bed fusion additive manufactured Ti-6Al-4V material.

The processing, structure, and property features for Ti-6Al-4V additively manufactured using laser powder bed fusion (L-PBF) over a range of processing parameter combinations are reported. In terms of processing, laser power and laser scanning speed were varied over a wide range, to investigate dense processing space as well as regimes likely to result in keyhole, lack of fusion, and beading up defects, which can occur during L-PBF. Archimedes measurements were used to measure porosity, while X-ray computed tomography (XCT) was used to quantify pore sizes, pore morphologies, and overall porosity, and finally, optical microscopy was used to quantify prior-ß grain characteristics. Average pore size and shape, porosity, prior- ß grain size and aspect ratio, and surface roughness for each processing parameter set are reported. Uniaxial tension tests and microhardness measurements were performed, with elastic modulus, yield strength, ultimate tensile strength, elongation to necking, elongation to fracture, and Vickers microhardness reported.

Incidence and outcomes of cardiogenic shock among women with spontaneous coronary artery dissection.

BACKGROUND: There is a paucity of data on cardiogenic shock (CS) incidence and outcomes among patients with spontaneous coronary artery dissection (SCAD). METHODS: Women admitted to the hospital for acute myocardial infarction (AMI) with and without SCAD were identified from the United States National Readmission Database from October 1, 2015 to December 31, 2018. We calculated the incidence of CS among women with AMI with and without SCAD and odds for developing CS after adjusting for baseline characteristics. In addition, we report the utilization of percutaneous coronary intervention, mechanical circulatory support, severe disability surrogates, and 30-day readmission rates. RESULTS: A total of 664,292 patients admitted for AMI were eligible for analysis, including 6643 patients with SCAD and 657,649 without SCAD. Patients with SCAD were younger (57 years [interquartile range, IQR 48-68] vs. 71 years [IQR 60-81], p < 0.01) and had fewer comorbidities yet had a higher incidence of CS as compared to patients without SCAD (9% vs. 5%, p < 0.01) and remained at elevated risk after adjusting for baseline comorbidities (adjusted odds ratio 1.5 [95% confidence interval, CI 1.2-1.7]). Among patients who developed CS, those with SCAD had lower in-hospital mortality than non-SCAD (31% vs. 39%, p < 0.01), and were more likely to receive mechanical circulatory support. CONCLUSIONS: In a nationally representative sample of women admitted for AMI, we found that patients with SCAD had a higher risk of developing CS and required more frequent use of mechanical circulatory support but were more likely to survive to discharge than women suffering AMI from causes other than SCAD.

Comparison Between Dichloroacetate and Phenylbutyrate Treatment for Pyruvate Dehydrogenase Deficiency.

Pyruvate dehydrogenase (PDH) deficiency is caused by a number of pathogenic variants and the most common are found in the PDHA1 gene. The PDHA1 gene encodes one of the subunits of the PDH enzyme found in a carbohydrate metabolism pathway involved in energy production. Pathogenic variants of PDHA1 gene usually impact the α-subunit of PDH causing energy reduction. It potentially leads to increased mortality in sufferers. Potential treatments for this disease include dichloroacetate and phenylbutyrate, previously used for other diseases such as cancer and maple syrup urine disease. However, not much is known about their efficacy in treating PDH deficiency. Effective treatment for PDH deficiency is crucial as carbohydrate is needed in a healthy diet and rice is the staple food for a large portion of the Asian population. This review analysed the efficacy of dichloroacetate and phenylbutyrate as potential treatments for PDH deficiency caused by PDHA1 pathogenic variants. Based on the findings of this review, dichloroacetate will have an effect on most PDHA1 pathogenic variant and can act as a temporary treatment to reduce the lactic acidosis, a common symptom of PDH deficiency. Phenylbutyrate can only be used on patients with certain pathogenic variants (p.P221L, p.R234G, p.G249R, p.R349C, p.R349H) on the PDH protein. It is hoped that the review would provide an insight into these treatments and improve the quality of lives for patients with PDH deficiency.

Temporal and geographical trends in women operators of electrophysiology procedures in the United States.

BACKGROUND: Cardiac electrophysiology (EP) has few women physicians. OBJECTIVE: The purpose of this study was to determine temporal and geographical trends in the proportion of women EP operators in the United States. METHODS: We extracted data from the Medicare Provider Utilization and Payment Database from 2013 to 2019 using procedure codes for atrial fibrillation (AF) ablation, supraventricular tachycardia/atrial flutter (SVT/AFL) ablation, and cardiac device implantation. The Medicare Provider Utilization and Payment Database excludes operators who perform ≤10 procedures annually for a given individual procedure code. The proportion of women operators was compared across the 7-year period. RESULTS: On average annually between 2013 and 2019, 5% (n = 187) of the 3524 EP operators were women. Procedure-specific analyses demonstrated a similarly low proportion of women EP operators across each procedure type. Despite a 137% increase in the total number of AF ablationists over the 7-year period, the proportion of women remained unchanged (P = .3966). The number of SVT/AFL ablationists and device operators remained constant over time as did the proportion of women operators (P = .9709 and .3583, respectively). In 2019, 10 states (20%) had no women EP operators who performed >10 of any given EP procedure annually, 20 states (39%) had no women who performed >10 of either AF or SVT/AFL ablation procedures annually, and 10 states (20%) had no women device operators who performed >10 of any given type of device implantation annually. CONCLUSION: Women EP operators remain underrepresented, and the proportion of women is stagnant even in areas of major clinical growth such as AF ablation. One-fifth of states had no women operators who performed >10 of any given EP procedure annually.

TAVR operator volumes, trends, and geographic variations amongst Medicare beneficiaries in the United States.

OBJECTIVES: To evaluate transcatheter aortic valve replacement (TAVR) operator procedural volumes, and describe temporal and geographic trends. BACKGROUND: TAVR is the standard of care for most patients with severe symptomatic aortic stenosis. Despite an association between operator procedural volume and outcomes, nationwide TAVR operator volumes have been incompletely described. METHODS: We queried the National Medicare Provider Utilization and Payment Database for transfemoral TAVRs from 2014 to 2018. Annual operator volume, state and regional volumes, and longitudinal trends were extracted and analyzed using descriptive statistics. RESULTS: In 2018, the mean annual operator volume was 23.6 TAVRs. The highest 1% of operators by volume performed 7.6% of total TAVR procedures in the United States, while 35.7% of operators performed 10 or fewer TAVRs per year. From 2014 to 2018, there was a 53.9% annualized increase in TAVRs, and the mean annual volume per operator grew from 12.5 to 23.6. There was more than five-fold variability in the density of operators (range 0.35-1.79 operators per 100,000 population) and mean operator volume by state (range 14.2-52.4 TAVRs per operator). CONCLUSIONS: In this nationally representative study of operators performing transfemoral TAVRs among Medicare patients, we found the mean annual volume of TAVR in 2018 to be 23.6 and has increased since 2014. There was considerable variability in operator density and procedural volumes, with a significant proportion of operators performing 10 or fewer TAVRs per year. Ambiguity remains in regard to the optimal balance of procedural requirements to sustain high efficacy outcomes and ensure critical access to TAVR therapies.

Forensic soil provenancing in an urban/suburban setting: A simultaneous multivariate approach.

Soil is a ubiquitous material at the Earth's surface with potential to be a useful evidence class in forensic and intelligence applications. Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier Transform InfraRed spectroscopy (FTIR) and geochemical data from X-Ray Fluorescence (XRF; for total major oxides) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS; for both total and aqua regia-soluble trace elements) are obtained from the survey's 268 topsoil samples (0-5 cm depth; 1 sample per km2 ). The simultaneous provenancing approach is underpinned by (i) the calculation of Spearman's correlation coefficients (rS ) between an evidentiary sample and all the samples in the database for all variables generated by each analytical method; and (ii) the preparation of an interpolated raster grid of rS for each evidentiary sample and method resulting in a series of provenance rasters ("heat maps"). The simultaneous provenancing method is tested on the North Canberra soil survey with three "blind" samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR (mineralogy) and XRF (geochemistry) analytical methods offer the most precise and accurate provenance predictions. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.

Clinical Predictors of Mortality in Patients with Moderate to Severe Mitral Regurgitation.

BACKGROUND: Mitral regurgitation is the most common form of valvular heart disease worldwide, however, there is an incomplete understanding of predictors of mortality in this population. This study sought to identify risk factors of mortality in a real-world population with mitral regurgitation. METHODS: All patients with moderate or severe mitral regurgitation were identified at a single center from January 1, 2016 to August 31, 2017. Multivariate regression was performed to evaluate variables independently associated with all-cause mortality. RESULTS: A total of 490 patients with moderate (76.3%) or severe (23.7%) mitral regurgitation due to primary (20.8%) or secondary (79.2%) etiology were identified. The mean age was 66.7 years; 50% were male. At a median follow-up of 3.1 years, the incidence of all-cause mortality was 30.1%, heart failure hospitalization 23.1%, and mitral valve intervention 11.6%. Of 117 variables, multivariate analysis demonstrated 5 that were independently predictive of mortality: baseline creatinine (hazard ratio [HR] 1.2; 95% CI, 1.0-1.3; P = .02), right atrial pressure by echocardiogram (HR 1.3; 95% CI, 1.07-1.55; P = .008), hemoglobin (HR 0.65; 95% CI, 0.52-0.83; P = .001), hospitalization for heart failure (HR 1.6; 95% CI, 1.1-2.4; P = .015), and mitral valve intervention (HR 0.40; 95% CI, 0.16-0.83; P = .049). CONCLUSION: In this retrospective, pragmatic analysis of patients with moderate or severe mitral regurgitation, admission for heart failure exacerbation, elevated right atrial pressure, renal dysfunction, anemia, and lack of mitral valve intervention were independently associated with increased risk of all-cause mortality. Whether these risk factors may better identify select patients who may benefit from more intensive monitoring or earlier intervention should be considered in future studies.

Six-Sigma Quality Management of Additive Manufacturing.

Quality is a key determinant in deploying new processes, products, or services and influences the adoption of emerging manufacturing technologies. The advent of additive manufacturing (AM) as a manufacturing process has the potential to revolutionize a host of enterprise-related functions from production to the supply chain. The unprecedented level of design flexibility and expanded functionality offered by AM, coupled with greatly reduced lead times, can potentially pave the way for mass customization. However, widespread application of AM is currently hampered by technical challenges in process repeatability and quality management. The breakthrough effect of six sigma (6S) has been demonstrated in traditional manufacturing industries (e.g., semiconductor and automotive industries) in the context of quality planning, control, and improvement through the intensive use of data, statistics, and optimization. 6S entails a data-driven DMAIC methodology of five steps-define, measure, analyze, improve, and control. Notwithstanding the sustained successes of the 6S knowledge body in a variety of established industries ranging from manufacturing, healthcare, logistics, and beyond, there is a dearth of concentrated application of 6S quality management approaches in the context of AM. In this article, we propose to design, develop, and implement the new DMAIC methodology for the 6S quality management of AM. First, we define the specific quality challenges arising from AM layerwise fabrication and mass customization (even one-of-a-kind production). Second, we present a review of AM metrology and sensing techniques, from materials through design, process, and environment, to postbuild inspection. Third, we contextualize a framework for realizing the full potential of data from AM systems and emphasize the need for analytical methods and tools. We propose and delineate the utility of new data-driven analytical methods, including deep learning, machine learning, and network science, to characterize and model the interrelationships between engineering design, machine setting, process variability, and final build quality. Fourth, we present the methodologies of ontology analytics, design of experiments (DOE), and simulation analysis for AM system improvements. In closing, new process control approaches are discussed to optimize the action plans, once an anomaly is detected, with specific consideration of lead time and energy consumption. We posit that this work will catalyze more in-depth investigations and multidisciplinary research efforts to accelerate the application of 6S quality management in AM.