Nickel as Electrocatalyst for CO(2) Reduction: Effect of Temperature, Potential, Partial Pressure, and Electrolyte Composition

Electrochemical CO2 reduction on Ni has recently been shown to have the unique ability to produce longer hydrocarbon chains in small but measurable amounts. However, the effects of the many parameters of this reaction remain to be studied in more detail. Here, we have investigated the effect of temperature, bulk CO2 concentration, potential, the reactant, cations, and anions on the formation of hydrocarbons via a chain growth mechanism on Ni. We show that temperature increases the activity but also the formation of coke, which deactivates the catalyst. The selectivity and thus the chain growth probability is mainly affected by the potential and the electrolyte composition. Remarkably, CO reduction shows lower activity but a higher chain growth probability than CO2 reduction. We conclude that hydrogenation is likely to be the rate-determining step and hypothesize that this could happen either by *CO hydrogenation or by termination of the hydrocarbon chain. These insights open the way to further development and optimization of Ni for electrochemical CO2 reduction.

How Temperature Affects the Selectivity of the Electrochemical CO2 Reduction on Copper

Copper is a unique catalyst for the electrochemical CO₂ reduction reaction (CO2RR) as it can produce multi-carbon products, such as ethylene and propanol. As practical electrolyzers will likely operate at elevated temperatures, the effect of reaction temperature on the product distribution and activity of CO2RR on copper is important to elucidate. In this study, we have performed electrolysis experiments at different reaction temperatures and potentials. We show that there are two distinct temperature regimes. From 18 up to ∼48 °C, C2+ products are produced with higher Faradaic efficiency, while methane and formic acid selectivity decreases and hydrogen selectivity stays approximately constant. From 48 to 70 °C, it was found that HER dominates and the activity of CO2RR decreases. Moreover, the CO2RR products produced in this higher temperature range are mainly the C1 products, namely, CO and HCOOH. We argue that CO surface coverage, local pH, and kinetics play an important role in the lower-temperature regime, while the second regime appears most likely to be related to structural changes in the copper surface.

Once in a blue moon: Primaquine-induced methemoglobinemia - A case report

Methemoglobinemia is a rare blood disorder that should be suspected in patients with cyanosis and low oxygen saturation of around 85%, especially when both do not improve despite supplemental oxygen. We describe the case of a 67-year-old lung transplant patient who was treated with primaquine and clindamycin because of a positive Pneumocystis jirovecii polymerase chain reaction on bronchoalveolar lavage fluid. Soon thereafter the patient developed increasing shortness of breath, central cyanosis and hypoxia, with an oxygen saturation of 86% on pulse oximetry despite supplemental oxygen. Arterial blood gas analysis showed a peculiar dark brown color and a significantly increased methemoglobin percentage. A diagnosis of methemoglobinemia due to primaquine was made. As treatment option, we preferred ascorbic acid over methylene blue because of concerns of possibly eliciting a serotonin syndrome. Our patient recovered rapidly after initiation of appropriate treatment. A high index of suspicion is crucial since this condition is potentially fatal.

Myocardial stiffness assessed by natural shear wave elastography is related to pressure-volume loop derived parameters

Background

Several cardiovascular disorders are accompanied by a stiffening of the myocardium and may result in diastolic heart failure. The non-invasive assessment of myocardial stiffness could therefore improve the understanding of the pathophysiology and guide treatment. Shear wave elastography (SWE) is a recent technique with tremendous potential for evaluating myocardial stiffness in a non-invasive way. Using high frame rate echocardiography, the propagation speed of shear waves is evaluated, which is directly related to the stiffness of the myocardium. These waves are induced by for instance mitral valve closure (MVC) and propagate throughout the cardiac muscle. However, validation of SWE against an invasive gold standard method is lacking.

Purpose

The aim of this study was to compare echocardiographic shear wave elastography against invasive pressure-volume loops, a gold standard reference method for assessing chamber stiffness.

Methods

In 15 pigs (31.2±4.1 kg) stiffness of the myocardium was acutely changed by inducing ischemia/reperfusion (I/R) injury. For this, the proximal LAD was balloon occluded for 90 minutes with subsequent reperfusion for 40 minutes. Conventional and high frame rate echocardiographic images were acquired simultaneously with pressure-volume loops during baseline conditions and after the induction of the I/R injury. Preload was reduced in order to acquire a set of pressure-volume loops to derive the end-diastolic pressure volume relation (EDPVR). From the EDPVR, the stiffness coefficient β and the operating chamber stiffness dP/dV were obtained. High frame rate echocardiographic datasets of the parasternal long axis view were acquired with an experimental ultrasound scanner (HD-PULSE) at an average frame rate of 1304±115 Hz. Tissue acceleration maps were obtained by drawing an M-mode line along the interventricular septum in order to visualize shear waves after MVC (at end-diastole). The propagation speed was assessed by semi-automatically measuring the slope (Figure A).

Results

I/R injury led to an elevated chamber stiffness constant β (0.09±0.03 1/ml vs. 0.05±0.01 1/ml; p<0.001) and operating chamber stiffness dP/dV (1.09±0.38 mmHg/ml vs. 0.50±0.18 mmHg/ml; p<0.01). Likewise, shear wave speed after MVC increased after the induction of the I/R injury in comparison to baseline (6.1±1.2 m/s vs. 3.2±0.8 m/s; p<0.001). Shear wave speed had a moderate positive correlation with β (r=0.63; p<0.001) (Figure B) and a strong positive correlation with dP/dV (r=0.81; p<0.001) (Figure C).

Conclusion

End-diastolic shear wave speed is strongly related to chamber stiffness, assessed invasively by pressure-volume loops. These results indicate that shear wave propagation speed could be used as a novel non-invasive measurement of the mechanical properties of the ventricle.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): FWO - Research Foundation Flanders

Thoracoscopic ablation for symptomatic atrial fibrillation improves quality of life

Background

Rhythm control has become an essential part of adequate management in atrial fibrillation (AF) to reduce symptoms and ultimately to improve health related quality of life (HRQoL). Totally thoracoscopic ablation has been established over the last years as an effective and safe rhythm control strategy, especially for persistent AF, but quality of life data are lacking.

Purpose

To assess the impact of totally thoracoscopic ablation on HRQoL in patients with symptomatic AF.

Methods

Consecutive patients with symptomatic AF undergoing totally thoracoscopic ablation at a referral centre in the Netherlands (July 2016 – October 2019) were included. The primary outcome was quality of life. Short Form 36 and Atrial Fibrillation Effect on Quality-of-Life (AFEQT) health surveys were collected at baseline, 1, 3, 6 and 12 months. Clinical improvement was measured as the relative increase of the QoL-score at 1 year compared to the baseline score (in %). Multilevel regression modelling was used, coupled with fractional polynomials for adjustment of age differences and nonlinear time trends, to investigate the one-year clinical trajectories of sex differences in QoL subscales. Secondary outcomes included rhythm success (freedom from any recurrence of atrial tachyarrhythmia>30 sec), mortality and stroke.

Results

191 patients were included (63.9±8.6 years, 68% male, 22.5% paroxysmal AF, 69.6% persistent AF and 7.9% long-term persistent AF, 66.5% having at least one previous failed catheter ablation, with median Cha2ds2 Vasc score of 2 [IQR 1–3]). AFEQT sum scores (52.6 points at baseline) substantially improved after three months (49.8%; p<0.001) and remained stable up to 1-year (54.2%; p<0.001) despite adverse events. Patients with recurrent AF also showed significant improvement at 3 months which remained stable up to 1-year, but patients who remained in sinus rhythm had significantly more increase (61.3% vs 26.9%, p<.001). The SF36 physical and mental summary composite scores significantly improved after 3 months (12.3% and 11.9% respectively; p<.001) and remained stable up to 1-year (16.9% and 16.4% respectively; P<.001). Although female patients had significantly lower AFEQT and physical subscales at baseline, similar improvement in scores were observed over time compared to men, adjusted for age and sex interactions (P<.001). One-year stroke rate was 1.6 per 100 patient-years with an oral anticoagulation rate of 63%. One-year survival was 99.5%.

Conclusions

This study reveals significant improvement of HRQoL three months after thoracoscopic ablation that persisted up to 1-year, also when adjusted for sex and age differences. Despite AF recurrence or adverse events AF related QoL still improved. Trials are necessary to confirm these data.

Funding Acknowledgement

Type of funding sources: None.

Monocyte-driven atypical cytokine storm and aberrant neutrophil activation as key mediators of COVID-19 disease severity

Epidemiological and clinical reports indicate that SARS-CoV-2 virulence hinges upon the triggering of an aberrant host immune response, more so than on direct virus-induced cellular damage. To elucidate the immunopathology underlying COVID-19 severity, we perform cytokine and multiplex immune profiling in COVID-19 patients. We show that hypercytokinemia in COVID-19 differs from the interferon-gamma-driven cytokine storm in macrophage activation syndrome, and is more pronounced in critical versus mild-moderate COVID-19. Systems modelling of cytokine levels paired with deep-immune profiling shows that classical monocytes drive this hyper-inflammatory phenotype and that a reduction in T-lymphocytes correlates with disease severity, with CD8+ cells being disproportionately affected. Antigen presenting machinery expression is also reduced in critical disease. Furthermore, we report that neutrophils contribute to disease severity and local tissue damage by amplification of hypercytokinemia and the formation of neutrophil extracellular traps. Together our findings suggest a myeloid-driven immunopathology, in which hyperactivated neutrophils and an ineffective adaptive immune system act as mediators of COVID-19 disease severity.

Does cardiac arrhythmia surgery improve a patient"s quality of life? a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Although one-year success of arrhythmia surgery for atrial fibrillation (AF) has long been defined as freedom from supraventricular tachyarrhythmia, patient-reported quality of life (QOL) has become increasingly important.

Purpose

We aimed to analyze current evidence of QOL following both concomitant and stand-alone arrhythmia surgery for AF.

Methods

Studies reporting on QOL of patients undergoing arrhythmia surgery for AF, stand-alone or concomitant, who provided essential data for the analysis, were included in this systematic review. A meta-analysis was performed on inter-study heterogeneity of changes in QOL in 9 of 12 included studies who used the Short-Form (SF) 36 tool. The metric standardized mean difference (SMD) was used to compare one year outcomes with baseline scores per variable of the SF-36 QOL questionnaire (total patients n = 545). Finally, meta-regression based on rhythm outcome after one year and add-on arrhythmia surgery as covariate were performed.

Results

QOL scores improved one year after surgical ablation for AF, evaluated by several questionnaires. In standalone arrhythmia procedures, meta-regression showed a significant improvement between the QOL and the procedural effectiveness after one year (Physical Functioning p = 0.015, Role Physical p = 0.006, General Health p = 0.002, Social Functioning p = 0.043. Forest plot Physical Functioning: SMD = 1.105; heterogeneity: I²=90.6%, p < 0.001). While this association was also suggested in concomitant procedures, only the variable Physical Role demonstrated a significant improvement when comparing QOL of cardiac surgery with and without add-on surgical AF ablation (p = 0.037).

Conclusion

Arrhythmia surgery for AF improves QOL. Both in standalone and concomitant procedures, the improvement in QOL seems to be related to the procedural effectiveness to maintain sinus rhythm after 12 months. Abstract Figure. SF-36 variable Physical Functioning

Real life experience with mTOR-inhibitors after lung transplantation

Mammalian target of rapamycin inhibitors (mTORi) are increasingly used after lung transplantation as part of a calcineurin inhibitor sparing regimen, aiming to preserve renal function. The aim of our study was to determine whether immunosuppressive therapy using mTORi in lung transplant recipients (LTR) is feasible in practice, or limited by intolerance and adverse events. Data were retrospectively assessed for all LTR transplanted between July 1991 and January 2020. Patients ever receiving mTORi (monotherapy or in combination with calcineurin inhibitor) as treatment of physicians' choice were included. 149/1184 (13%) of the LTR ever received mTORi. Main reasons to start were renal insufficiency (67%) and malignancy (21%). In 52% of the patients, mTORi was stopped due to side effects or drug toxicity after a median time of 159 days. Apart from death, main reasons for discontinuation were infection (19%) and edema (14%). Early discontinuation (<90 days) was mainly due to edema or gastrointestinal intolerance. As mTORi was stopped due to adverse events or drug intolerance in 52% of LTR, cautious consideration of advantages and disadvantages when starting mTORi is recommended.