Multicomponent Azide-Alkyne Cycloaddition Catalyzed by Impregnated Bimetallic Nickel and Copper on Magnetite

A new bimetallic catalyst derived from nickel and copper has been used successfully for the first time in the multicomponent reaction of terminal alkynes, sodium azide, and benzyl bromide derivatives. The presence of both metallic species on the surface of magnetite seems to have a positive and synergetic effect. The catalyst loading is the lowest ever published for a catalyst of copper anchored on any type of iron support. The catalyst could be easily removed from the reaction media just by magnetic decantation and it could be reused up to ten times without any negative effect on the initial results.

Copper-Impregnated Magnetite as a Heterogeneous Catalyst for the Homocoupling of Terminal Alkynes

Copper-impregnated magnetite is a versatile heterogeneous catalytic system for the synthesis of 1,3-diynes by the homocoupling of terminal alkynes. This catalyst does not require the use of pressurized oxygen as the oxidant and it does not need a solvent or harsh conditions to give the expected products. Moreover, the catalyst can be removed from the reaction medium simply by using a magnet. The reaction occurs at the lowest copper loading reported for any heterogeneous catalyst.

Catheter-related bloodstream infection: burden of disease in a tertiary hospital

Background: Surveillance programmes have become the most effective tool for controlling catheter-related bloodstream infections (CRBSI). However, few studies have investigated programmes covering all hospital settings. Aim: To describe the results of a control and prevention programme for CRBSI based on compliance with recommendations for insertion and maintenance, using annual burden of disease in a tertiary level hospital. Methods: A CRBSI control and prevention programme involving all hospital settings was implemented. The programme consisted of CRBSI surveillance, direct observation of insertion and maintenance of catheters to determine performance, and education for healthcare workers. Findings: In total, 2043 short-term catheters were inserted in 1546 patients for 18,570 catheter-days, and 279 long-term catheters were inserted in 243 patients for 40,440 catheter-days. The annual incidence density was 5.98 (first semester 6.40, second semester 5.64) CRBSI per 1000 catheter-days for short-term catheters, and 0.57 (first semester 0.66, second semester 0.43) CRBSI per 1000 catheter-days for long-term catheters. One hundred and forty insertion procedures were observed, with an average insertion time of 13 (standard deviation 7) min. Compliance with recommendations was as follows: hand hygiene, 86.8%; use of alcoholic chlorhexidine solution for skin disinfection, 35.5%; use of mask, 93.4%; use of gloves, 98.7%; use of gown, 75.0%; use of sterile cloth, 93.8%; use of cap, 92.2%; bandage application, 62.7%; and use of aseptic technique, 89.5%. Forty-five maintenance procedures were observed, and compliance rates were as follows: hand hygiene, 42.1%; use of gloves, 78.1%; and port disinfection with alcoholic chlorhexidine solution, 32.5%. Conclusion: The CRBSI control and prevention programme implemented at the study hospital has decreased the rate of CRBSI, provided important information about the total burden of disease, and revealed possible ways to improve interventions in the future.

Ductile Metal Oxides Impregnated on Magnetite: New Catalysts in Organic Synthesis

Ramón's group has designed a simple, robust and inexpensive methodology for the impregnation of different transition metal oxides on the surface of magnetite and their use in catalysis.

Activated Carbons Impregnated with Na2S and H2SO4: Texture, Surface Chemistry and Application to Mercury Removal from Aqueous Solutions

The effects of treatment of an activated carbon with Sulphur precursors on its textural properties and on the ability of the complex synthesized for mercury removal in aqueous solutions are studied. To this end, a commercial activated carbon has been modified by treatments with aqueous solutions of Na2S and H2SO4 at two temperatures (25 and 140 °C) to introduce sulphur species on its surface. The prepared adsorbents have been characterized by N2 (-196 °C) and CO2 (0 °C) adsorption, thermogravimetric analysis, temperature-programmed decomposition and X-ray photoelectron spectroscopy, and their adsorption capacities to remove Hg(II) ions in aqueous solutions have been determined. It has been shown that the impregnation treatments slightly modified the textural properties of the samples, with a small increase in the textural parameters (BET surface area and mesopore volumes). By contrast, surface oxygen content was increased when impregnation was carried out with Na2S, but it decreased when H2SO4 was used. However, the main effect of the impregnation treatments was the formation of surface sulphur complexes of thiol type, which was only achieved when the impregnation treatments were carried out at low temperature (25 °C). The presence of surface sulphur enhances the adsorption behaviour of these samples in the removal of Hg(II) cations in aqueous solutions at pH 2. In fact, complete Hg(II) removal is only obtained with the sulphur-containing activated carbons.

Cobalt-Impregnated Magnetite as General Heterogeneous Catalyst for the Hydroacylation Reaction of Azodicarboxylates

Catalysts consisting of cobalt and nickel impregnated on magnetite have been prepared, characterized and used for the hydroacylation reaction of different azodicarboxylate compounds with aldehydes, using nearly stoichiometric amounts of both reagents in only 3 h. Furthermore, this reaction has been conducted with the smallest amount of catalyst. The cobalt catalyst is stable enough to be removed by magnetic decantation and recycled ten-fold without any detrimental effect on the results.

Osmium impregnated on magnetite as a heterogeneous catalyst for the syn-dihydroxylation of alkenes

A new catalyst derived from osmium has been prepared, fully characterized and tested in the dihydroxylation of alkenes. The catalyst was prepared by wet impregnation methodology of OsCl3·3H2O on a commercial micro-magnetite surface. The catalyst allowed the reaction with one of the lowest osmium loadings for a heterogeneous catalyst and was selective for the monodihydroxylation of 1,5-dienes. Moreover, the catalyst was easily removed from the reaction medium by the simple use of a magnet. The selectivity of catalyst is very high with conversions up to 99%. Preliminary kinetics studies showed a first-order reaction rate with respect to the catalyst.

Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles

Palladium impregnated on magnetite is an efficient, cheap and easy to prepare catalyst for the direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated products, at the C2- or C3-position (depending of the heterocycle used). The methodology can be extended to prepare chromenes through an intramolecular direct arylation reaction. Some evidence is provided for two catalyst deactivation pathways, which prevents efficient recycling.

Cross-dehydrogenative coupling reaction using copper oxide impregnated on magnetite in deep eutectic solvents

The synthesis of different tetrahydroisoquinolines using choline chloride : ethylene glycol as a deep eutectic solvent (DES) and copper(II) oxide impregnated on magnetite as a catalyst has been accomplished successfully. The copper catalyst amount is the lowest loading ever reported. The presence of DES showed to be essential since the reaction in the absence of this medium did not proceed. A direct proportional relationship was found between the conductivity of DES medium and the yield obtained. The DES and the catalyst could be reused up to ten times without any detrimental effect on the yield of the reaction, with the aerobic conditions making the protocol highly sustainable, where the only waste is water.

Palladium(II) oxide impregnated on magnetite as a catalyst for the synthesis of 4-arylcoumarins via a Heck-arylation/cyclization process

Heck-arylation/cyclization was achieved using heterogeneous palladium(II) oxide impregnated on magnetite catalyst (2.5 mol%) with a lower catalyst loading than that reported for similar processes. Ethanol was used as a non-toxic and bio-renewable solvent. Good yields were afforded using a broad range of substrates (40–98%). The catalyst could be partially recycled, and analyses confirmed the almost total reduction of palladium(II) oxide to palladium(0) as well as the iodine poissoning effect, which is the main barrier to complete recyclability.

Rivaroxabananddabigatraninpatientsundergoing catheter ablation of atrial fibrillation

Aims: The recent availability of the novel oral anticoagulants (NOACs) may have led to a change in the anticoagulation regimens of patients referred to catheter ablation of atrial fibrillation (AF). Preliminary data exist concerning dabigatran, but information regarding the safety and efficacy of rivaroxaban in this setting is currently scarce. Methods: and results Of the 556 consecutive eligible patients (age 61.0 ± 9.6; 74.6% men; 61.2% paroxysmal AF) undergoing AF catheter ablation in our centre (October 2012 to September 2013) and enroled in a systematic standardized 30-day follow-up period: 192 patients were under vitamin K antagonists (VKAs), 188 under rivaroxaban, and 176 under dabigatran. Peri-procedural mortality and significant systemic or pulmonary thromboembolism (efficacy outcome), as well as bleeding events (safety outcome) during the 30 days following the ablation were evaluated according to anticoagulation regimen. During a 12-month time interval, the use of the NOACs in this population rose from <10 to 70%. Overall, the rate of events was low with no significant differences regarding: thrombo-embolic events in 1.3% (VKA 2.1%; rivaroxaban 1.1%; dabigatran 0.6%; P = 0.410); major bleeding in 2.3% (VKA 4.2%; rivaroxaban 1.6%; dabigatran 1.1%; P = 0.112), and minor bleeding 1.4% (VKA 2.1%; rivaroxaban 1.6%; dabigatran 0.6%; P = 0.464). No fatal events were observed. Conclusion: The use of the NOAC in patients undergoing catheter ablation of AF has rapidly evolved (seven-fold) over 1 year. These preliminary data suggest that rivaroxaban and dabigatran in the setting of catheter ablation of AF are efficient and safe, compared with the traditional VKA.

Propofol sedation administered by cardiologists for patients undergoing catheter ablation for ventricular tachycardia

AIMS Propofol sedation has been shown to be safe for atrial fibrillation ablation and internal cardioverter-defibrillator implantation but its use for catheter ablation (CA) of ventricular tachycardia (VT) has yet to be evaluated. Here, we tested the hypothesis that VT ablation can be performed using propofol sedation administered by trained nurses under a cardiologist's supervision. METHODS AND RESULTS Data of 205 procedures (157 patients, 1.3 procedures/patient) undergoing CA for sustained VT under propofol sedation were analysed. The primary endpoint was change of sedation and/or discontinuation of propofol sedation due to side effects and/or haemodynamic instability. Propofol cessation was necessary in 24 of 205 procedures. These procedures (Group A; n = 24, 11.7%) were compared with those with continued propofol sedation (Group B; n = 181, 88.3%). Propofol sedation was discontinued due to hypotension (n = 22; 10.7%), insufficient oxygenation (n = 1, 0.5%), or hypersalivation (n = 1, 0.5%). Procedures in Group A were significantly longer (210 [180-260] vs. 180 [125-220] min, P = 0.005), had a lower per hour propofol rate (3.0 ± 1.2 vs. 3.8 ± 1.2 mg/kg of body weight/h, P = 0.004), and higher cumulative dose of fentanyl administered (0.15 [0.13-0.25] vs. 0.1 [0.05-0.13] mg, P < 0.001), compared with patients in Group B. Five (2.4%) adverse events occurred. CONCLUSION Sedation using propofol can be safely performed for VT ablation under the supervision of cardiologists. Close haemodynamic monitoring is required, especially in elderly patients and during lengthy procedures, which carrying a higher risk for systolic blood pressure decline.

Epicardial phrenic nerve displacement during catheter ablation of atrial and ventricular arrhythmias: procedural experience and outcomes.

BACKGROUND Arrhythmia origin in close proximity to the phrenic nerve (PN) can hinder successful catheter ablation. We describe our approach with epicardial PN displacement in such instances. METHODS AND RESULTS PN displacement via percutaneous pericardial access was attempted in 13 patients (age 49±16 years, 9 females) with either atrial tachycardia (6 patients) or atrial fibrillation triggered from a superior vena cava focus (1 patient) adjacent to the right PN or epicardial ventricular tachycardia origin adjacent to the left PN (6 patients). An epicardially placed steerable sheath/4 mm-catheter combination (5 patients) or a vascular or an esophageal balloon (8 patients) was ultimately successful. Balloon placement was often difficult requiring manipulation via a steerable sheath. In 2 ventricular tachycardia cases, absence of PN capture was achieved only once the balloon was directly over the ablation catheter. In 3 atrial tachycardia patients, PN displacement was not possible with a balloon; however, a steerable sheath/catheter combination was ultimately successful. PN displacement allowed acute abolishment of all targeted arrhythmias. No PN injury occurred acutely or in follow up. Two patients developed acute complications (pleuro-pericardial fistula 1 and pericardial bleeding 1). Survival free of target arrhythmia was achieved in all atrial tachycardia patients; however, a nontargeted ventricular tachycardia recurred in 1 patient at a median of 13 months' follow up. CONCLUSIONS Arrhythmias originating in close proximity to the PN can be targeted successfully with PN displacement with an epicardially placed steerable sheath/catheter combination, or balloon, but this strategy can be difficult to implement. Better tools for phrenic nerve protection are desirable.

Role of alternative interventional procedures when endo- and epicardial catheter ablation attempts for ventricular arrhythmias fail.

BACKGROUND Ventricular tachycardia (VT) refractory to antiarrhythmic drugs and standard percutaneous catheter ablation techniques portends a poor prognosis. We characterized the reasons for ablation failure and describe alternative interventional procedures in this high-risk group. METHODS AND RESULTS Sixty-seven patients with VT refractory to 4±2 antiarrhythmic drugs and 2±1 previous endocardial/epicardial catheter ablation attempts underwent transcoronary ethanol ablation, surgical epicardial window (Epi-window), or surgical cryoablation (OR-Cryo; age, 62±11 years; VT storm in 52%). Failure of endo/epicardial ablation attempts was because of VT of intramural origin (35 patients), nonendocardial origin with prohibitive epicardial access because of pericardial adhesions (16), and anatomic barriers to ablation (8). In 8 patients, VT was of nonendocardial origin with a coexisting condition also requiring cardiac surgery. Transcoronary ethanol ablation alone was attempted in 37 patients, OR-Cryo alone in 21 patients, and a combination of transcoronary ethanol ablation and OR-Cryo (5 patients), or transcoronary ethanol ablation and Epi-window (4 patients), in the remainder. Overall, alternative interventional procedures abolished ≥1 inducible VT and terminated storm in 69% and 74% of patients, respectively, although 25% of patients had at least 1 complication. By 6 months post procedures, there was a significant reduction in defibrillator shocks (from a median of 8 per month to 1; P<0.001) and antiarrhythmic drug requirement although 55% of patients had at least 1 VT recurrence, and mortality was 17%. CONCLUSIONS A collaborative strategy of alternative interventional procedures offers the possibility of achieving arrhythmia control in high-risk patients with VT that is otherwise uncontrollable with antiarrhythmic drugs and standard percutaneous catheter ablation techniques.