The impact of ECG synchronization during acquisition of left­atrium computed tomography model on radiation dose and arrhythmia recurrence rate after catheter ablation of atrial fibrillation - a prospective, randomized study.

BACKGROUND: The impact of ECG gating during computed tomography (CT) acquisition of left atrium (LA) model on radiation dose, image quality and ablation event-free survival rate after catheter ablation (CA) of atrial fibrillation (AF) is not well defined. METHODS: Sixty-two patients with paroxysmal atrial fibrillation were randomized for two types of LA CT (with vs without ECG gating) before CA. Pulmonary veins isolation was performed in all patients. Patients were followed for 12 months after CA. RESULTS: There was no difference between the groups in CA length (131.61±32.57 vs 119.84±33.18 min; p=0.108), CA fluoroscopy time (4.48±2.19 vs 3.89±1.83 min; p=0.251), CA fluoroscopy dose (3.99±2.79 vs 3.91 vs2.91 Gy*cm2; p=0.735), visual data quality (1.77±0.88 vs 2.0±0.63; p=0.102) and registration error (2.42±0.72 vs 2.43±0.46 mm; p=0.612). We found a significant difference in CT Dose index (89.55±5.99 vs 19.19±4.33 mGy; p<0.0001) and Dose Length product (1438.87±147.75 vs 328.21±73.83 mGy*cm; p<0.0001). Twelve months after CA, 25 of 31 patients in the gated group and 24 of 31 patients in the non-gated group were free of AF (80.65 vs 77.42 %; p=0.838). CONCLUSION: ECG gating of computed tomography of LA before AF ablation burdens patients with a four times higher radiation dose while improving neither the quality of CT model or fusion of CT with the electroanatomic map. As a result, it has no significant impact on arrhythmia recurrence rate after ablation (Tab. 3, Fig. 3, Ref. 25).

Red or white wine consumption effect on atherosclerosis in healthy individuals (In Vino Veritas study).

AIMS: Consumption of wine has a protective effect on cardiovascular diseases. Data from prospective, long-term, head-to-head comparisons of effects of different drinks on markers of atherosclerosis have been insufficient. METHODS AND RESULTS: In Vino Veritas (IVV) study is long-term, prospective, multi-centre, randomized trial comparing effects of red and white wine on atherosclerosis. 157 healthy subjects were randomized to white or red wine consumption for one year. We did not find increase in HDL-cholesterol in the whole group (1.66±0.58 vs 1.62±0.49, p=0.180) or difference between both groups (1.60±0.53 vs 1.64±0.46, p=0.634). At 12 months there was reduction of LDL-cholesterol in both groups, but with no difference between the groups (3.37±0.75 vs 3.60±1.10, p=0.134); there was no difference between the groups in total cholesterol, CRP, fasting blood glucose and liver function tests. Both groups had comparable differences from baseline in levels of parameters of oxidative stress. CONCLUSION: We did not find any clinically relevant differences in the lipid profile, CRP, fasting blood glucose and other markers of atherosclerosis, between long-term consumption of red and white wine. Moreover, we were unable to confirm the hypothesis that wine drinking is associated with an elevation of HDL (Tab. 7, Fig. 1, Ref. 30).

Growth of transition metals on cerium tungstate model catalyst layers.

Two model catalytic metal/oxide systems were investigated by photoelectron spectroscopy and scanning tunneling microscopy. The mixed-oxide support was a cerium tungstate epitaxial thin layer grown in situ on the W(1 1 0) single crystal. Active particles consisted of palladium and platinum 3D islands deposited on the tungstate surface at 300 K. Both metals were found to interact weakly with the oxide support and the original chemical state of both support and metals was mostly preserved. Electronic and morphological changes are discussed during the metal growth and after post-annealing at temperatures up to 700 K. Partial transition-metal coalescence and self-cleaning from the CO and carbon impurities were observed.

Depth profiling of ultra-thin alumina layers grown on Co(0001).

Epitaxial thin oxide layers were grown by simultaneous aluminum deposition and oxidation on a Co(0001) single crystal, and the metal-oxide interface between the substrate and the grown layer was studied using photoelectron spectroscopy. The oxide layers were composed of two kinds of chemically different layers. Angle-resolved measurements were used to determine the compositions of oxide sub-layers and to reveal their respective thicknesses. The topmost oxide layers were up to 0.23 nm thick, determined by analysis of O 1s and Co 2p(3/2) photoelectron spectra. The results of the analysis show that the interface layer is composed of a mixture of oxygen and cobalt atoms and its thickness is approximately 0.6 nm. The analysis of Co 2p(3/2), Al 2p(3/2) and O 1s core level binding energies confirmed the presence of CoO in the interface layer and Al(2)O(3) in the topmost oxide layer.

Investigation of the Ti/MgCl2 interface on a Si(111) 7 × 7 substrate.

Photoelectron spectroscopy with synchrotron radiation, low energy electron diffraction, and ion-scattering spectroscopy were used in order to study the Ti/MgCl(2) interface grown on an atomically clean Si(111) 7 × 7 substrate. A series of high resolution spectra after deposition of a thick MgCl(2) layer, step by step deposition of Ti and gradual annealing, indicated a very reactive interface even at room temperature. Strong interaction between the incoming Ti atoms and the MgCl(2) layer, leads to the formation of Ti(2+) and Ti(4+) oxidation states. The interfacial interaction continues even at multilayer Ti coverage mainly by the partial disruption of Mg-Cl bonds and the formation of Ti-Cl sites, rendering this interface a very promising UHV-compatible model of a pre-catalyst for olefin polymerization. After the final annealing, the MgCl(2) multilayers desorb while Ti remains on the surface forming a silicide layer on which Cl and Mg atoms are attached.

Sn/Pt(110) bimetallic surfaces: formation and oxygen adsorption.

Submonolayer coverage of Sn on a Pt(110) surface was studied by photoemission and low-energy electron diffraction. Deposition of less than 0.6 ML at 300 K gives rise to a c(2 × 2) surface reconstruction with weak diffraction spots at the very beginning of growth, and no other LEED patterns were found at this temperature. A new (4 × 1) Sn/Pt(110) surface structure was observed after flashing to 570 K a coverage of 0.64 ML. The total Sn coverage decreased to 0.58 ML after flashing as some of the atoms diffused into deeper layers. Different Sn phases were identified on the (4 × 1) Sn/Pt(110) surface: two types of surface Sn atoms in different adsorption sites, a subsurface Sn-Pt intermetallic layer and Sn-Pt surface islands. To investigate chemical reactivity, 0.25 ML Sn/Pt(110) and 0.58 ML (4 × 1) Sn/Pt(110) surfaces were exposed to 1000 L of O(2) at 300 K. Analyses of the photoemission data provide evidence for the formation of tin oxide. The interaction with oxygen of the two surfaces is similar, independent of surface structure and the composition of the subsurface layers. The Sn concentration in the interface intermetallic layer is the main factor which influences the oxygen adsorption.

Interaction of tungsten with CeO2(111) layers as a function of temperature: a photoelectron spectroscopy study.

The interaction of tungsten with CeO(2)(111) layers grown on Cu(111) was studied in the temperature range between 300 and 870 K by photoelectron spectroscopy of the core levels and resonant valence band spectroscopy. The interaction was found to be very strong even at 300 K, leading to the formation of cerium tungstate Ce(6)WO(12) in which the metal atoms were in Ce(3+) and W(6+) chemical states. The growth was limited by the diffusion of W atoms into the ceria layer, so subsequent tungsten deposition led to formation of W suboxides with consecutively lower chemical oxidation states, i.e. W(4+), W(2+) and metallic W(0) with an almost negligible contribution of W(5+). Step-wise annealing of the layer showed that due to stimulated diffusion of tungsten into ceria at higher temperature, Ce(6)WO(12) was formed more easily. Larger W overlayer thicknesses needed higher annealing temperature to promote diffusion. The thickest sample studied, 1.4 nm W/CeO(2), was transformed by annealing to 870 K to the Ce(6)WO(12)/W system with a tungsten monoxide (WO) interface, whereas the rest of the tungsten was converted to the W(6 + ) oxidation state.

The interfacial properties of MgCl(2) thin films grown on Ti(0001).

Photoelectron spectroscopy with synchrotron radiation (SRPES), temperature programmed desorption (TPD), low energy electron diffraction (LEED), and ion-scattering spectroscopy (ISS) were used in order to study the MgCl(2)/Ti(0001) interface. A clear hexagonal LEED pattern confirmed the presence of a quite large grain of Ti(0001) on the substrate while no new superstructure was formed after deposition of MgCl(2) either at room or at elevated temperatures. A series of high resolution spectra after step by step MgCl(2) deposition and gradual annealing indicated strong interaction between MgCl(2) and the substrate while ISS measurements showed that there is no migration of Ti atoms into the deposit layers. Additional quantities of deposited MgCl(2) grew stoichimetrically on top of the chemically active interface. Annealing at approximately 350 degrees C caused clustering of the MgCl(2) multilayer and TPD results showed that they desorbed stoichimetrically at temperatures between 360 and 380 degrees C. The interfacial TiCl(x)Mg(y) species dissociated by the disruption of the Cl-Mg bonds at temperatures higher than 400 degrees C and metallic Mg evaporated. The Cl atoms remained attached on the Ti surface but they did not form any ordered structure even after annealing at 730 degrees C. The present results indicate the occurrence of charge transfer at the Ti/MgCl(2) interface through the Cl ligands and provide valuable information for catalyst design.

Excitons at the B K edge of boron nitride nanotubes probed by x-ray absorption spectroscopy.

We have performed a near-edge x-ray absorption fine-structure (NEXAFS) investigation of multi-walled boron nitride nanotubes (BNNTs). We show that the one-dimensionality of BNNTs is clearly evident in the B K edge spectrum, while the N K edge spectrum is similar to that of layered hexagonal BN (h-BN). We observe a sharp feature at the σ* onset of the B K edge, which we ascribe to a core exciton state. We also report a comparison with spectra taken after an ammonia plasma treatment, showing that the B K edge becomes indistinguishable from that of h-BN, due to the breaking of the tubular order and the formation of small h-BN clusters.

A resonant photoemission applied to cerium oxide based nanocrystals.

Cerium 4f level occupation determines the properties of cerium oxide based catalysts in a significant way. The Ce 4f level of nanosized cerium oxide particles was investigated with the use of resonant photoelectron spectroscopy in the Ce 4d-4f photoabsorption region. A strong interaction of ceria with different additives, e.g. Pd and Sn, led to a partial Ce4+-->Ce3+ transition that was observed as a significant resonance enhancement of 4f photoemission intensity. Increases of the CO oxidation catalytic activity were observed simultaneously. The ratio of resonance enhancement of Ce photoemission intensity DCe(3+)/DCe(4+) was used to monitor Ce(3+) and Ce(4+) state occupation. The relative parameter DCe(3+)/DCe(4+) was found to be particularly useful in the case of photoemission studies of nanopowder ceria catalysts.

Interaction of Au with CeO2(111): A photoemission study.

We have studied the adsorption of low dimensional gold on ceria, produced by evaporation onto the surface. The interaction of gold with CeO(2)(111) layers was investigated with x-ray photoemission spectroscopy, ultraviolet photoemission spectroscopy, and resonant photoelectron spectroscopy (RPES). Gold was deposited in steps onto a 1.5 nm thick CeO(2)(111) layer epitaxially grown on a Cu(111) substrate. The RPES showed a partial Ce(4+)-->Ce(3+) reduction, observed as a resonant enhancement of the 4f level of the Ce(3+) species. This can be explained by possible creation of a new Au(+) ionic state. The observed effects are stronger for Au deposition at room temperature than at 250 degrees C. The obtained results are in agreement with already published density functional theory calculations reporting weakening of bond between the oxygen and the Ce atoms in ceria caused by the presence of gold.

Palladium interaction with CeO(2), Sn-Ce-O and Ga-Ce-O layers.

Using photoemission, we have studied the interaction of palladium with thin layers of stoichiometric ceria (Ce(4+) character) and two mixed oxides, Ga-Ce-O and Sn-Ce-O, where cerium in the Ce(3+) oxidation state is present. Palladium was found to partially reduce the CeO(2) layer by introducing oxygen vacancies most probably in the vicinity of the growing Pd particles. In mixed oxide systems palladium very strongly interacts with both added metals-gallium and tin-leading to a breaking of metal-ceria bonds and the establishment of Pd-Ga(Sn) intermetallic compounds. As a consequence the ceria reoxidizes back to a Ce(4+) oxidation state.

Low pressure oxidation of ordered Sn/Pd(110) surface alloys.

The reaction of oxygen at low pressure with the Sn/Pd(110) system has been examined by photoelectron spectroscopy using synchrotron radiation. The c(2 × 2) and (3 × 1) reconstructions of the Sn/Pd(110) surface at 0.5 and 0.7 monolayers (ML) Sn coverage and a 1.75 ML Sn overlayer on the Pd(110) surface after flashing to 470 K were studied. The Sn 4d core level is strongly affected by O(2) adsorption while the Pd 3d core level shows very little change other than a decrease in intensity. Starting with a 10 L dose of oxygen, prominent changes in the spectra were observed for all Sn/Pd(110) surface alloys. Analysis of the Sn 4d core levels indicates that oxidation proceeds with the formation of well-defined states of Sn, which were identified as a Pd-Sn-O interface layer, SnO and SnO(2) oxides. The valence band spectra confirm this assignment. The Sn(2+) and Sn(4+) component signals originate from the topmost surface layer, i.e. tin atoms in more highly oxidized states constitute the topmost surface layer on top of the Pd-Sn-O interface. The presence of a sub-surface PdSn intermetallic alloy facilitates the tin oxide formation; the Sn-O phase formation is accompanied by Pd-Sn bond dissociation.

[The importance of determining the viability of the myocardium prior to revascularisation in patients with ischaemic cardiomyopathy and left ventricular systolic dysfunction]. / Význam stanovení viability myokardu pred revaskularizací u pacientu s ischemickou kardiomyopatií a systolickou dysfunkcí levé komory srdecní.

Chronic heart failure is a worldwide clinical syndrome with substantial socio-economical impact. The aim of this overview is the summary of contemporary knowledge in epidemiology, elementary pathophysiological implications and some possibilities of treatment of ischemic cardiomyopathy, which represents the most frequent cause of heart failure in developed countries. Emphasis is on the right indication for myocardial revascularization as a causal option of therapy of ischemic cardiomyopathy, timing and risk of revascularization and especially on importance of assessment of viability of myocardium using presently available imaging methods.

Electronic structure of cluster assembled nanostructured TiO(2) by resonant photoemission at the Ti L(2,3) edge.

The electronic structure of cluster assembled nanostructured TiO(2) thin films has been investigated by resonant photoemission experiments with photon energies across the Ti L(2,3) edge. The samples were produced by supersonic cluster beam deposition with a pulsed microplasma cluster source. The valence band shows resonance enhancements in the binding energy region between 4 and 8 eV, populated by O 2p and hybridized Ti 3d states, and in the region about 1 eV below the Fermi level associated with defects related Ti 3d states. The data show that in as-deposited films Ti atoms are mainly fully (sixfolds) coordinated to oxygen atoms in octahedral symmetry and only a small fraction is in a broken symmetry environment. Since resonant photoemission is closely linked to the local electronic and structural configurations around the Ti atom, it is possible to correlate the resonant photoemission intensity and lineshape with the presence of defects of the films and with the degree of hybridization between the titanium and oxygen atoms.

[Malignant arrhythmia in a patient with variant (Prinzmetal's) angina pectoris]. / Maligní arytmie u pacienta s variantní (Prinzmetalovou) anginou pectoris.

Malignant arrhythmia is a frequent complication of myocardial ischemia due to the occurrence of coronary artery spasm. The paper describes a patient with variant angina pectoris with an ICD implant who was repeatedly resuscitated for circulatory arrest in malignant arrhythmia. During myocardial ischemia the ECG showed elevations in the ST segments in the region of the ventral cardiac wall, with the formation of permanent polymorphous chamber tachycardia. External defibrillation was necessary due to recurrent tachyarrhythmias. A spasm developed when the RIA (radio immuno assay) was introduced during coronarography. The spasm started in the periphery of the artery and extended as far as the area of bifurcation with RD, with transitory closure of the artery and the development of chamber tachycardia. The patient fully recovered after the addition of Ca-blocker, nitrate depot and the withdrawal of the beta-blocker.