Implantation of a novel insertable cardiac monitor: preliminary multicenter experience in Europe

BACKGROUND

The LUX-Dx™ is a novel insertable cardiac monitor (ICM) introduced into the European market since October 2022.

PURPOSE

The aim of this investigation was to provide a comprehensive description of the ICM implantation experience in Europe during its initial year of commercial use.

METHODS

The system comprises an incision tool and a single-piece insertion tool pre-loaded with the small ICM. The implantation procedure involves incision, creation of a device pocket, insertion of the ICM, verification of sensing, and incision closure. Patients receive a mobile device with a preloaded App, connecting to their ICM and transmitting data to the management system. Data collected at European centers were analyzed at the time of implantation and before patient discharge.

RESULTS

A total of 368 implantation procedures were conducted across 23 centers. Syncope (235, 64%) and cryptogenic stroke (34, 9%) were the most frequent indications for ICM. Most procedures (338, 92%) were performed in electrophysiology laboratories. All ICMs were successfully implanted in the left parasternal region, oriented at 45° in 323 (88%) patients. Repositioning was necessary after sensing verification in 9 (2%) patients. No procedural complications were reported, with a median time from skin incision to suture of 4 min (25th-75th percentiles 2-7). At implantation, the mean R-wave amplitude was 0.39 ± 0.30 mV and the P-wave visibility was 91 ± 20%. Sensing parameters remained stable until pre-discharge and were not influenced by patient characteristics or indications. Procedural times were fast, exhibited consistency across patient groups, and improved after an initial experience with the system. Operator Operator feedback on the system was positive. Patients reported very good ease of use of the App and low levels of discomfort after implantation.

CONCLUSIONS

LUX-Dx™ implantation appears efficient and straightforward, with favorable post-implantation sensing values and associated with positive feedback from operators and patients.

Monitoring Cr toxicity and remediation processes - combining a whole-cell bioreporter and Cr isotope techniques

Bioremediation is a sustainable and cost-effective means of contaminant detoxification. Although Cr(VI) is toxic at high concentrations, various microbes can utilise it as an electron accepter in the bioremediation process, and reduce it to the less toxic form Cr(III). During remediation, it is important to monitor the level of toxicity and effectiveness of Cr(VI) reduction in order to optimize the conditions. This study employed a whole-cell bioreporter Acinetobacter baylyi ADPWH-recA to access the degree of toxicity of different species of Cr over a range of initial concentrations. It also investigated whether Cr isotope fractionation factors were impacted by different levels of Cr toxicity (related to its concentration) and Cr(VI) reduction rates by Cr resistant bacteria Pseudomonas fluorescens LB 300. The results show that, of both Cr₂O₇^2- and CrO₄^2-, the whole-cell bioreporter was efficient in indicating the level of genotoxicity of Cr(VI) at low concentrations and cytotoxicity at high concentrations via variations of bioluminescence. High concentrations (> 100 mg/L) of Cr(III) could also strongly induce the luminescence in the bioreporter, indicating DNA damage at such abundance. Pseudomonas fluorescens LB 300 was found to be effective in reducing Cr(VI) even when the concentration was high (40 mg/L); however, complete Cr(VI) reduction was only observed at low concentrations (< 5 mg/L), since the toxicity of high concentrations of Cr(VI) impacted the effectiveness of reduction by the bacteria. During reduction, the C53r/C52r ratio of remaining Cr(VI) increased from its initial value, and the calculated fractionation factor by bacterial Cr(VI) reduction (ε) was -3.1±0.3‰. The fractionation factor was independent of the initial Cr(VI) concentration. Therefore, a single Cr isotope fractionation factor can be effectively applied in indicating the extent of bioremediation processing of Cr(VI) over a wide range of concentrations. This significantly simplified monitoring of Cr(VI) depletion in bioremediation, since variations of ε normally indicate a change in the reduction mechanism and therefore would complicate the elucidation of processes driving the remediation.

Using stable isotope fractionation factors to identify Cr(VI) reduction pathways: Metal-mineral-microbe interactions

Microbes interact with metals and minerals in the environment altering their physical and chemical states, whilst in turn metals and minerals impact on microbial growth, activity and survival. The interactions between bacteria and dissolved chromium in the presence of iron minerals, and their impact on Cr isotope variations, were investigated. Cr(VI) reduction experiments were conducted with two bacteria, Pseudomonas fluorescens LB 300 and Shewanella oneidensis MR-1, in the presence of two iron oxide minerals, goethite and hematite. Both minerals were found to inhibit the rates of Cr(VI) reduction by Pseudomonas, but accelerated those of Shewanella. The Cr isotopic fractionation factors generated by Shewanella were independent of the presence of the minerals (ε = -2.3‰). For Pseudomonas, the ε value was the same in both the presence and absence of goethite (-3.3‰); although, it was much higher (ε = -4.3‰) in the presence of hematite. The presence of aqueous Fe(III) in solution had no detectable impact on either bacterial Cr reduction rates nor isotopic fractionation factors. The presence of aqueous Fe(II) induced rapid abiotic reduction of Cr(VI). The different effects that the presence of Fe minerals had on the Cr fractionation factors and reduction rates of the different bacterial species may be attributed to the way each bacteria attached to the minerals and their different reduction pathways. SEM images confirmed that Pseudomonas cells were much more tightly packed on the mineral surfaces than were Shewanella. The images also confirmed that Shewanella oneidensis MR-1 produced nanowires. The results suggest that the dominant Cr(VI) reduction pathway for Pseudomonas fluorescens LB 300 may have been through membrane-bound enzymes, whilst for Shewanella oneidensis MR-1 it was probably via extracellular electron transfer. Since different minerals impact differentially on bacterial Cr(VI) reduction and isotope fractionation, variations of mineralogies and the associated changes of bacterial communities should be taken into consideration when using Cr isotopes to quantify Cr redox behaviour in the environment.

Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES

Continental shelves and shelf seas play a central role in the global carbon cycle. However, their importance with respect to trace element and isotope (TEI) inputs to ocean basins is less well understood. Here, we present major findings on shelf TEI biogeochemistry from the GEOTRACES programme as well as a proof of concept for a new method to estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment micronutrient fluxes and basin-scale estimates of submarine groundwater discharge. The proposed shelf flux tracer is 228-radium (T1/2 = 5.75 yr), which is continuously supplied to the shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf 228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from the western North Atlantic margin. The results from this new approach agree well with previous estimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmospheric deposition by factors of approximately 3-23. Lastly, recommendations are made for additional GEOTRACES process studies and coastal margin-focused section cruises that will help refine the model and provide better insight on the mechanisms driving shelf-derived TEI fluxes to the ocean.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

Comparative study of chemical and physical methods for distinguishing between passive and metabolically active mechanisms of water contaminant removal by biofilms

In this study, physical and chemical approaches were employed to distinguish between passive and active mechanisms in biofilms removing contaminants in waste waters and their relative merits were assessed. Respiration, post-exposure recovery and scanning electron microscopic analysis demonstrated that both ultraviolet (UV) treatment (300 mJ/cm(2)) and sodium azide (10 mM) completely inhibited metabolic activity at 5 and 24 h exposure, respectively, whilst not damaging the integrity of the biofilms. Amongst the commonly used chemical inhibitors, only sodium azide showed complete inhibition after 24 h incubation with only about 10% (±4%) of biofilm carbon released into the bulk solution, compared to 33-41% (±8%) when exposed to 5 mM and 10 mM 2,4-dinitrophenol (DNP) and 69-80% (±5%) when exposed to 2% and 5% w/v formalin, respectively. Biofilm inhibition with UV and sodium azide was found to be equally effective at inhibiting biofilms for treatment of triethanolamine (TEA) and benzotriazole (BTA): the results confirming that the dominant removal mechanism was biodegradation. However, the rates of glucose removal by sodium azide-inhibited biofilms were similar to controls, suggesting that chemical inhibitors were not effective for distinguishing the removal mechanisms of simple sugars. Statistically similar amounts of metal were removed by biofilms treated with UV and sodium azide in zinc, copper and cadmium single-systems: the results indicated that the removal mechanism is predominantly a passive biosorption process.

Advanced Residuals Analysis for Determining the Number of PARAFAC Components in Dissolved Organic Matter

Parallel factor analysis (PARAFAC) has facilitated an explosion in research connecting the fluorescence properties of dissolved organic matter (DOM) to its functions and biogeochemical cycling in natural and engineered systems. However, the validation of robust PARAFAC models using split-half analysis requires an oft unrealistically large number (hundreds to thousands) of excitation-emission matrices (EEMs), and models with too few components may not adequately describe differences between DOM. This study used self-organizing maps (SOM) and comparing changes in residuals with the effects of adding components to estimate the number of PARAFAC components in DOM from two data sets: MS (110 EEMs from nine leaf leachates and headwaters) and LR (64 EEMs from the Lena River). Clustering by SOM demonstrated that peaks clearly persisted in model residuals after validation by split-half analysis. Plotting the changes to residuals was an effective method for visualizing the removal of fluorophore-like fluorescence caused by increasing the number of PARAFAC components. Extracting additional PARAFAC components via residuals analysis increased the proportion of correctly identified size-fractionated leaf leachates from 56.0 ± 0.8 to 75.2 ± 0.9%, and from 51.7 ± 1.4 to 92.9 ± 0.0% for whole leachates. Model overfitting was assessed by considering the correlations between components, and their distributions amongst samples. Advanced residuals analysis improved the ability of PARAFAC to resolve the variation in DOM fluorescence, and presents an enhanced validation approach for assessing the number of components that can be used to supplement the potentially misleading results of split-half analysis.

The environmental genomics of metazoan thermal adaptation

Continued and accelerating change in the thermal environment places an ever-greater priority on understanding how organisms are going to respond. The paradigm of ‘move, adapt or die', regarding ways in which organisms can respond to environmental stressors, stimulates intense efforts to predict the future of biodiversity. Assuming that extinction is an unpalatable outcome, researchers have focussed attention on how organisms can shift in their distribution to stay in the same thermal conditions or can stay in the same place by adapting to a changing thermal environment. How likely these respective outcomes might be depends on the answer to a fundamental evolutionary question, namely what genetic changes underpin adaptation to the thermal environment. The increasing access to and decreasing costs of next-generation sequencing (NGS) technologies, which can be applied to both model and non-model systems, provide a much-needed tool for understanding thermal adaptation. Here we consider broadly what is already known from non-NGS studies about thermal adaptation, then discuss the benefits and challenges of different NGS methodologies to add to this knowledge base. We then review published NGS genomics and transcriptomics studies of thermal adaptation to heat stress in metazoans and compare these results with previous non-NGS patterns. We conclude by summarising emerging patterns of genetic response and discussing future directions using these increasingly common techniques.

Partitioning experiments in the laser-heated diamond anvil cell: volatile content in the Earth's core

The present state of the Earth evolved from energetic events that were determined early in the history of the Solar System. A key process in reconciling this state and the observable mantle composition with models of the original formation relies on understanding the planetary processing that has taken place over the past 4.5Ga. Planetary size plays a key role and ultimately determines the pressure and temperature conditions at which the materials of the early solar nebular segregated. We summarize recent developments with the laser-heated diamond anvil cell that have made possible extension of the conventional pressure limit for partitioning experiments as well as the study of volatile trace elements. In particular, we discuss liquid-liquid, metal-silicate (M-Sil) partitioning results for several elements in a synthetic chondritic mixture, spanning a wide range of atomic number-helium to iodine. We examine the role of the core as a possible host of both siderophile and trace elements and the implications that early segregation processes at deep magma ocean conditions have for current mantle signatures, both compositional and isotopic. The results provide some of the first experimental evidence that the core is the obvious replacement for the long-sought, deep mantle reservoir. If so, they also indicate the need to understand the detailed nature and scale of core-mantle exchange processes, from atomic to macroscopic, throughout the age of the Earth to the present day.

Numerical models, geochemistry and the zero-paradox noble-gas mantle

Numerical models of whole-mantle convection demonstrate that degassing of the mantle is an inefficient process, resulting in ca. 50% of the (40)Ar being degassed from the mantle system. In this sense the numerical simulations are consistent with the (40)Ar mass balance between the atmosphere and mantle reservoir. These models, however, are unable to preserve the large-scale heterogeneity predicted by models invoking geochemical layering of the mantle system. We show that the three most important noble-gas constraints on the geochemically layered mantle are entirely dependent on the (3)He concentration of the convecting mantle derived from the (3)He flux into the oceans and the average ocean-crust generation rate. A factor of 3.5 increase in the convecting-mantle noble-gas concentration removes all requirements for: a (3)He flux into the upper mantle from a deeper high (3)He source; a boundary in the mantle capable of separating heat from helium; and a substantial deep-mantle reservoir to contain a hidden (40)Ar rich reservoir. We call this model concentration for the convecting mantle the 'zero-paradox' concentration. The time-integrated flux of (3)He into the oceans is a robust observation, but only representative of the ocean-floor activity over the last 1000 years. In contrast, ocean-floor generation occurs over tens of millions of years. We argue that combining these two observations to obtain the (3)He concentration of the mantle beneath mid-ocean ridges is unsound. Other indicators of mantle (3)He concentration suggest that the real value may be at least a factor of two higher. As the zero-paradox concentration is approached, the noble-gas requirement for mantle layering is removed. We further consider the role that recycled material plays in ocean-island-basalt generation and show that a source with high (3)He and (3)He/(4)He must exist within the mantle. Nevertheless, only a small amount of this material is required to generate both the observed ocean-island (3)He/(4)He ratios and the concentrations inferred from basalt samples for this mantle source.

Hypothyroidism in patients with thalassemia syndromes

Sixty transfusion-dependent thalassemic patients were studied by simultaneous measurement of circulating thyroid hormones, basal thyroid-stimulating hormone (TSH) and TSH response to thyrotropin-releasing hormone with the aim of evaluating the frequency of hypothyroidism in such patients, and the relationship between hypothyroidism and compliance with treatment and iron overload. Thyroid failure was present in 31 of the 60 patients. A correlation was found between impairment of thyroid functions, duration of chronic hypoxia and the activities of various transaminases. The results of this study emphasize the importance of early evaluation of thyroid function in thalassemic patients and suggest that anemia and hypoxia may potentiate the toxicity of iron deposition in endocrine glands.

Interferences in the spectrophotometric S-diphenylcarbazide determination of environmental hexavalent chromium in a chromium and zinc plating plant

A study on the determination of environmental hexavalent chromium [Cr(VI)] was carried out in a chromium and zinc plating plant. The atmospheric particulate was collected both on glass wool filters and with an electrostatic sampler; Cr(VI) was determined by the S-diphenylcarbazide method. The filtered and electrostatically collected Cr(VI) was extracted with both 1.4% sulfuric acid and 7% sodium carbonate. Strong interference was observed when extraction was carried out with the acid medium. Alkaline extraction permits 95 +/- 6 (+/- SD)% recovery of the total chromium and has been shown to be suitable in releasing Cr(VI). The analyses of the alkaline samples were carried out with the standard addition method to compensate for a depressive interference of 26 +/- 8 (+/- SD)%. The absorbance decrease of the Cr-S-diphenylcarbazide complex is a time function, and it should be measured within a few minutes of the reagent addition.