Cardiovascular magnetic resonance characterization of peri-infarct zone remodeling following myocardial infarction

<p>Abstract</p> <p>Background</p> <p>Clinical studies implementing late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) studies suggest that the peri-infarct zone (PIZ) contains a mixture of viable and non-viable myocytes, and is associated with greater susceptibility to ventricular tachycardia induction and adverse cardiac outcomes. However, CMR data assessing the temporal formation and functional remodeling characteristics of this complex region are limited. We intended to characterize early temporal changes in scar morphology and regional function in the PIZ.</p> <p>Methods and results</p> <p>CMR studies were performed at six time points up to 90 days after induction of myocardial infarction (MI) in eight minipigs with reperfused, anterior-septal infarcts. Custom signal density threshold algorithms, based on the remote myocardium, were applied to define the infarct core and PIZ region for each time point. After the initial post-MI edema subsided, the PIZ decreased by 54% from day 10 to day 90 (<it>p </it>= 0.04). The size of infarct scar expanded by 14% and thinned by 56% from day 3 to 12 weeks (<it>p </it>= 0.004 and <it>p </it>< 0.001, respectively). LVEDV increased from 34.7. ± 2.2 ml to 47.8 ± 3.0 ml (day3 and week12, respectively; p < 0.001). At 30 days post-MI, regional circumferential strain was increased between the infarct scar and the PIZ (-2.1 ± 0.6 and -6.8 ± 0.9, respectively;* <it>p </it>< 0.05).</p> <p>Conclusions</p> <p>The PIZ is dynamic and decreases in mass following reperfused MI. Tensile forces in the PIZ undergo changes following MI. Remodeling characteristics of the PIZ may provide mechanistic insights into the development of life-threatening arrhythmias and sudden cardiac death post-MI.</p

The Gaia-ESO Survey: Pre-Main Sequence Stars in the Young Open Cluster NGC 3293

The young open cluster NGC3293 is included in the observing program of the Gaia-ESO survey (GES). The radial velocity values provided have been used to assign cluster membership probabilities by means of a single-variable parametric analysis. These membership probabilities are compared to the results of the photometric membership assignment of NGC3293, based on UBV RI photometry. The agreement of the photometric and kinematic member samples amounts to 65%, and could increase to 70% as suggested by the analysis of the differences between both samples. A number of photometric PMS candidate members of spectral type F are found, which are confirmed by the results from VPHAS photometry and SED fitting for the stars in common with VPHAS and GES data sets. Excesses at mid- and near-infrared wavelengths, and signs of Hα emission, are investigated for them. Marginal presence of Hα emission or infilling is detected for the candidate members. Several of them exhibit moderate signs of U excess and weak excesses at mid-IR wavelengths. We suggest that these features originate from accretion disks in their last stages of evolution

Feasibility and initial experience of assessment of mechanical dyssynchrony using cardiovascular magnetic resonance and semi-automatic border detection

<p>Abstract</p> <p>Background</p> <p>The systolic dyssynchrony index (SDI) has been introduced as a measure of mechanical dyssynchrony using three-dimensional echocardiography to select patients who may benefit from cardiac resynchronization therapy (CRT). However, three-dimensional echocardiography may be inadequate in a number of patients with suboptimal acoustic window and no single echocardiographic measure of dyssynchrony has proven to be of value in selecting patients for CRT. Thus, the aim of this study was to determine the value of cardiovascular magnetic resonance (CMR) for the assessment of the SDI in patients with reduced LV function as well as in healthy controls using semi-automatic border tracking.</p> <p>Methods</p> <p>We investigated a total of 45 patients including 35 patients (65 ± 8 years) with reduced LV function (EF 30 ± 11%) and a wide QRS complex as well as 10 control subjects (42 ± 21 years, EF 70 ± 11%). For cine imaging a standard SSFP imaging sequence was used with a temporal resolution of 40 frames per RR-interval. Quantitative analysis was performed off-line using a software prototype for semi-automatic border detection. Global volumes, ejection fraction and the SDI were calculated in each subject. SDI was compared with standard echocardiographic parameters of dyssynchrony.</p> <p>Results</p> <p>The mean SDI differed significantly between patients (14 ± 5%) and controls (5 ± 2%, p < 0.001). An exponential correlation between the EF and the SDI was observed (r = -0.84; p < 0.001). In addition, a significant association between the SDI and the standard deviation of time to peak systolic motion of 12 LV segments (Ts-SD) determined by echocardiography was observed (r = 0.66, p = 0.002).</p> <p>Conclusion</p> <p>The results of this preliminary study suggest that CMR with semi-automatic border detection may be useful for the assessment of mechanical dyssynchrony in patients with reduced LV function.</p> <p>No trial registration due to recruitment period between October 2004 and November 2006</p

The Gaia-ESO Survey: the selection function of the Milky Way field stars

The Gaia-ESO Survey was designed to target all major Galactic components (i.e. bulge, thin and thick discs, halo and clusters), with the goal of constraining the chemical and dynamical evolution of the Milky Way. This paper presents the methodology and considerations that drive the selection of the targeted, allocated and successfully observed Milky Way field stars. The detailed understanding of the survey construction, specifically the influence of target selection criteria on observed Milky Way field stars is required in order to analyse and interpret the survey data correctly. We present the target selection process for the Milky Way field stars observed with Very Large Telescope/Fibre Large Array Multi Element Spectrograph and provide the weights that characterize the survey target selection. The weights can be used to account for the selection effects in the Gaia-ESO Survey data for scientific studies. We provide a couple of simple examples to highlight the necessity of including such information in studies of the stellar populations in the Milky Way

Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines

Aims. We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II] and He I of nebular emission in the central part of the Carina Nebula. Methods. We investigate the properties of the two already known kinematic components (approaching and receding, respectively), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km/s) gas emission. Results. We show that gas giving rise to Hα and He I emission is dynamically well correlated, but not identical, to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arises from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the starWR25. Such “shells" are non-spherical, and show distortions probably caused by collisions with other shells or colder, higher-density gas. Part of them is also obscured by foreground dust lanes, while only very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum

The Gaia-ESO Survey: Pre-main-sequence stars in the young open cluster NGC 3293

© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.The young open cluster NGC3293 is included in the observing program of the Gaia-ESO survey (GES). The radial velocity values provided have been used to assign cluster membership probabilities by means of a single-variable parametric analysis. These membership probabilities are compared to the results of the photometric membership assignment of NGC3293, based on UBVRI photometry. The agreement of the photometric and kinematic member samples amounts to 65 per cent, and could increase to 70 per cent as suggested by the analysis of the differences between both samples. A number of photometric PMS candidate members of spectral type F are found, which are confirmed by the results from VPHAS photometry and SED fitting for the stars in common with VPHAS and GES data sets. Excesses at mid- and near-infrared wavelengths, and signs of Hα emission, are investigated for them. Marginal presence of Hα emission or infilling is detected for the candidate members. Several of them exhibit moderate signs of U excess and weak excesses at mid-IR wavelengths. We suggest that these features originate from accretion discs in their last stages of evolution

Circumferential myocardial strain in cardiomyopathy with and without left bundle branch block

<p>Abstract</p> <p>Background</p> <p>Cardiac resynchronization therapy (CRT) has been shown to decrease mortality in 60-70% of advanced heart failure patients with left bundle branch block (LBBB) and QRS duration > 120 ms. There have been intense efforts to find reproducible non-invasive parameters to predict CRT response. We hypothesized that different left ventricular contraction patterns may exist in LBBB patients with depressed systolic function and applied tagged cardiovascular magnetic resonance (CMR) to assess circumferential strain in this population.</p> <p>Methods</p> <p>We determined myocardial circumferential strain at the basal, mid, and apical ventricular level in 35 subjects (10 with ischemic cardiomyopathy, 15 with non-ischemic cardiomyopathy, and 10 healthy controls). Patterns of circumferential strain were analyzed. Time to peak systolic circumferential strain in each of the 6 segments in all three ventricular slices and the standard deviation of time to peak strain in the basal and mid ventricular slices were determined.</p> <p>Results</p> <p>Dyskinesis of the anterior septum and the inferior septum in at least two ventricular levels was seen in 50% (5 out of 10) of LBBB patients while 30% had isolated dyskinesis of the anteroseptum, and 20% had no dyskinesis in any segments, similar to all of the non-LBBB patients and healthy controls. Peak circumferential strain shortening was significantly reduced in all cardiomyopathy patients at the mid-ventricular level (LBBB 9 ± 6%, non-LBBB 10 ± 4% vs. healthy 19 ± 4%; both p < 0.0001 compared to healthy), but was similar among the LBBB and non-LBBB groups (p = 0.20). The LBBB group had significantly greater dyssynchrony compared to the non-LBBB group and healthy controls assessed by opposing wall delays and 12-segment standard deviation (LBBB 164 ± 30 ms vs. non-LBBB 70 ± 17 ms (p < 0.0001), non-LBBB vs. healthy 65 ± 17 ms (p = 0.47)).</p> <p>Conclusions</p> <p>Septal dyskinesis exists in some patients with LBBB. Myocardial circumferential strain analysis enables detailed characterization of contraction patterns, strengths, and timing in cardiomyopathy patients with and without LBBB.</p

The Gaia-ESO Survey: Spectroscopic-asteroseismic analysis of K2 stars in Gaia-ESO

The extensive stellar spectroscopic datasets that are available for studies in Galactic Archeaology thanks to, for example, the Gaia-ESO Survey, now benefit from having a significant number of targets that overlap with asteroseismology projects such as Kepler, K2 and CoRoT. Combining the measurements from spectroscopy and asteroseismology allows us to attain greater accuracy with regard to the stellar parameters needed to characterise the stellar populations of the Milky Way. The aim of this Gaia-ESO Survey special project is to produce a catalogue of self-consistent stellar parameters by combining measurements from high-resolution spectroscopy and precision asteroseismology. We carried out an iterative analysis of 90 K2@Gaia-ESO red giants. The spectroscopic values of Teff were used as input in the seismic analysis to obtain log(g) values. The seismic estimates of log(g) were then used to re-determine the spectroscopic values of Teff and [Fe/H]. Only one iteration was required to obtain parameters that are in good agreement for both methods and thus, to obtain the final stellar parameters. A detailed analysis of outliers was carried out to ensure a robust determination of the parameters. The results were then combined with Gaia DR2 data to compare the seismic log(g) with a parallax-based log(g) and to investigate instances of variations in the velocity and possible binaries within the dataset. This analysis produced a high-quality catalogue of stellar parameters for 90 red giant stars observed by both K2 and Gaia-ESO that were determined through iterations between spectroscopy and asteroseismology. We compared the seismic gravities with those based on Gaia parallaxes to find an offset which is similar to other studies that have used asteroseismology. Our catalogue also includes spectroscopic chemical abundances and radial velocities, as well as indicators for possible binary detections