161 research outputs found
Advances in the on-site and remote-controlled analysis of dissolved (noble) gases in water bodies
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Glass-ceramic with preferred orientation of Li2Si205 crystals produced by extrusion below crystallization temperature and subsequent heat treatment
Glass-ceramics with oriented crystals have been produced from a lithium disilicate glass system by extruding the nucleated glass below the crystallization temperature, and subsequent heat treatment to achieve high-crystalline glass-ceramics. The extruded glass was found to possess a small amount of ahgned, elongated lithium disilicate crystallites and anisotropic stresses. The resulting glassceramic shows a high orientation of the needle-shaped Li₂Si₂O₅ crystals with their c-axis parallel to the extrusion direction. The degree of crystallographic orientation was found to be decreased for samples with an additional heat treatment slightly above Tg, placed between the extrusion process and the crystallization. The crystal alignment of specimens extruded below crystallization temperature is significantly higher than the alignment o f extruded glass-ceramic
Comparison of 2D and 3D calculation of left ventricular torsion as circumferential-longitudinal shear angle using cardiovascular magnetic resonance tagging
<p>Abstract</p> <p>Purpose</p> <p>To compare left ventricular (LV) torsion represented as the circumferential-longitudinal (CL) shear angle between 2D and 3D quantification, using cardiovascular magnetic resonance (CMR).</p> <p>Methods</p> <p>CMR tagging was performed in six healthy volunteers. From this, LV torsion was calculated using a 2D and a 3D method. The cross-correlation between both methods was evaluated and comparisons were made using Bland-Altman analysis.</p> <p>Results</p> <p>The cross-correlation between the curves was <it>r</it><sup>2 </sup>= 0.97 ± 0.02. No significant time-delay was observed between the curves. Bland-Altman analysis revealed a significant positive linear relationship between the difference and the average value of both analysis methods, with the 2D results showing larger values than the 3D. The difference between both methods can be explained by the definition of the 2D method.</p> <p>Conclusion</p> <p>LV torsion represented as CL shear quantified by the 2D and 3D analysis methods are strongly related. Therefore, it is suggested to use the faster 2D method for torsion calculation.</p
Myocardial Structural Alteration and Systolic Dysfunction in Preclinical Hypertrophic Cardiomyopathy Mutation Carriers
BACKGROUND: To evaluate the presence of myocardial structural alterations and subtle myocardial dysfunction during familial screening in asymptomatic mutation carriers without hypertrophic cardiomyopathy (HCM) phenotype. METHODS AND FINDINGS: Sixteen HCM families with pathogenic mutation were studied and 46 patients with phenotype expression (Mut+/Phen+) and 47 patients without phenotype expression (Mut+/Phen-) were observed. Twenty-five control subjects, matched with the Mut+/Phen- group, were recruited for comparison. Echocardiography was performed to evaluate conventional parameters, myocardial structural alteration by calibrated integrated backscatter (cIBS) and global and segmental longitudinal strain by speckle tracking analysis. All 3 groups had similar left ventricular dimensions and ejection fraction. Basal anteroseptal cIBS was the highest in Mut+/Phen+ patients (-14.0+/-4.6 dB, p-19.0 dB basal anteroseptal cIBS or >-18.0% basal anteroseptal longitudinal strain had a sensitivity of 98% and a specificity of 72% in differentiating Mut+/Phen- group from controls. CONCLUSION: The use of cIBS and segmental longitudinal strain can differentiate HCM Mut+/Phen- patients from controls with important clinical implications for the family screening and follow-up of these patients.published_or_final_versio
Cardiac resynchronization therapy; the importance of evaluating cardiac metabolism
Cardiac Dysfunction and Arrhythmia
Review of journal of cardiovascular magnetic resonance 2010
There were 75 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2010, which is a 34% increase in the number of articles since 2009. The quality of the submissions continues to increase, and the editors were delighted with the recent announcement of the JCMR Impact Factor of 4.33 which showed a 90% increase since last year. Our acceptance rate is approximately 30%, but has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. Last year for the first time, the Editors summarized the papers for the readership into broad areas of interest or theme, which we felt would be useful to practitioners of cardiovascular magnetic resonance (CMR) so that you could review areas of interest from the previous year in a single article in relation to each other and other recent JCMR articles [1]. This experiment proved very popular with a very high rate of downloading, and therefore we intend to continue this review annually. The papers are presented in themes and comparison is drawn with previously published JCMR papers to identify the continuity of thought and publication in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication
Evidence of scar tissue: contra-indication to cardiac resynchronization therapy?
Ventricular Dysfunction & Heart Failur
Determinants of myocardial energetics and efficiency in symptomatic hypertrophic cardiomyopathy
Next to hypertrophy, hypertrophic cardiomyopathy (HCM) is characterized by alterations in myocardial energetics. A small number of studies have shown that myocardial external efficiency (MEE), defined by external work (EW) in relation to myocardial oxidative metabolism (MVO2), is reduced. The present study was conducted to identify determinants of MEE in patients with HCM by use of dynamic positron emission tomography (PET) and cardiovascular magnetic resonance imaging (CMR). Twenty patients with HCM (12 men, mean age: 55.2 +/- 13.9 years) and 11 healthy controls (7 men, mean age: 48.1 +/- 10 years) were studied with [C-11]acetate PET to assess MVO2. CMR was performed to determine left ventricular (LV) volumes and mass (LVM). Univariate and multivariate analyses were employed to determine independent predictors of myocardial efficiency. Between study groups, MVO2 (controls: 0.12 +/- 0.04 ml center dot min(-1)center dot g(-1), HCM: 0.13 +/- 0.05 ml center dot min(-1)center dot g(-1), p = 0.64) and EW (controls: 9,139 +/- 2,484 mmHg center dot ml, HCM: 9,368 +/- 2,907 mmHg center dot ml, p = 0.83) were comparable, whereas LVM was significantly higher (controls: 99 +/- 21 g, HCM: 200 +/- 76 g, p < 0.001) and MEE was decreased in HCM patients (controls: 35 +/- 8%, HCM: 21 +/- 10%, p < 0.001). MEE was related to stroke volume (SV), LV outflow tract gradient, NH2-terminal pro-brain natriuretic peptide (NT-proBNP) and serum free fatty acid levels (all p < 0.05). Multivariate analysis revealed that SV ( = 0.74, p < 0.001) and LVM ( = -0.43, p = 0.013) were independently related to MEE. HCM is characterized by unaltered MVO2, impaired EW generation per gram of myocardial tissue and subsequent deteriorated myocardial efficiency. Mechanical external efficiency could independently be predicted by SV and LVM
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