1,720,985 research outputs found
Right ventricular strain as a novel approach to analyze right ventricular performance in patients with heart failure
No full textSpeckle tracking echocardiography (STE) has recently applied as imaging technique to accurately evaluate right ventricular (RV) function. STE provides a non-Doppler, angle-independent and objective quantification of RV myocardial deformation. Data regarding feasibility, accuracy and clinical applications of RV strain are rapidly gathering, especially in the setting of heart failure patients. This review describes the fundamental concepts of RV-STE and discusses its emerging clinical applications, focusing on the useful of this technique in the clinical management of patients with advanced heart failure
Physiologic determinants of left ventricular systolic torsion assessed by speckle tracking echocardiography in healthy subjects
No full textBACKGROUND: The associations of left ventricular (LV) systolic torsion with clinical and echocardiographic variables in physiological conditions have not been fully investigated. We explored the independent determinants of LV systolic torsion in a population of normal subjects.
METHODS: In 119 healthy subjects, peak twist angle (LVtw) and torsion (LVtor) during ejection, and the QRS-LVtw interval (time-to-peak LVtw) were measured by speckle tracking. LV twisting rate and rotational deformation delay were also determined.
RESULTS: Stepwise multiple regression showed that LVtw was independently associated with indexed end-systolic volume (β=-0.200, P < 0.0001), peak early diastolic mitral annulus velocity (β=-0.186, P = 0.0001), heart rate (β= 0.178, P = 0.0003), and male gender (β=-0.174, P = 0.0004). Similar results were found for LVtor. Age was the only parameter, which has demonstrated an independent correlation with time-to-peak LVtw (β= 0.329, P < 0.0001). Despite significance of these associations, the proportions of variability explained by regression models were relatively low (range 11-26%), and no accurate predictive models were identifiable for LV twisting rate and rotational deformation delay.
CONCLUSION: In normal individuals, indexed end-systolic LV volume, LV relaxation, heart rate, gender, and age correlate independently with LV torsion mechanics. However, conventional echocardiographic and clinical variables are not able to predict LV torsion mechanics
Acute effects of an energy drink on myocardial function assessed by conventional echo-Doppler analysis and by speckle tracking echocardiography on young healthy subjects
Full text linkPurpose. Previous studies have underlined the effects of the energy drinks containing caffeine end taurine on the cardiovascular system. The aim of this study was to determine acute changes on echocardiographic parameters assessed by conventional echo-Doppler analysis and by speckle tracking echocardiography after the consumption of an energy drink in a young healthy population. Methods. measurement of blood pressure, electrocardiographic, and echocardiographic examination were performed on 35 healthy subjects (mean age 25 ± 2 years, 16 men), at baseline and one hour after the consumption of a body surface area indexed amount of an energy drink (168 mL/m(2)) containing caffeine (0.03%) and taurine (0.4%). Results. The analysis of left ventricular function showed a significant increase of mean relative values of MAPSE (+11%; P < 0.001), global longitudinal strain (+10%, P = 0.004), and left ventricular twisting (+22%, P < 0.0001) in respect to baseline. Also, right ventricular function parameters appeared significantly increased after energy drink consumption, as TAPSE (+15%, P < 0.0001), global, and free wall right ventricular longitudinal strain (+8%, P = 0.001; +5%, P = 0.1, resp.). Conclusion. In conclusion, the consumption of the ED in our population showed a significant increase of right and left ventricular myocardial function, suggesting a possible positive inotropic effect related to the substances contained therein
Effect of the direct renin inhibitor aliskiren in association with valsartan versus highly-dosed valsartan on cardiac function in patients with hypertension and left ventricular hypertrophy.
No full textRight ventricular strain is a stronger predictor of prognosis than left ventricular analysis in patients referred for heart transplantation
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Left Ventricular Deformation and Myocardial Fibrosis in Patients With Advanced Heart Failure Requiring Transplantation
No full textPurpose: To evaluate potential relationships between different components of left ventricular (LV) function and histopathological evidence for myocardial fibrosis in patients undergoing heart transplantation. Methods: The study population included patients with advanced heart failure, referred for an echocardiographic examination before heart transplantation. Traditional LV function measurements and global longitudinal strain (GLS) by speckle tracking echocardiography, averaging all LV segments in 4-, 2-, and 3-chamber views were obtained in all subjects. LV tissue samples were obtained from all patients who underwent heart transplantation. Myocardial fibrosis was assessed using Masson's staining. Results: Of 106 patients referred for cardiac transplantation, 47 underwent cardiac transplantation and were enrolled in the study. LV myocardial fibrosis and its grade strongly correlated with GLS (r = 0.75, P = .0001), modestly with global circumferential strain and LV torsion (r = 0.61, P = .001 and r = 0.52, P = .01, respectively) and weakly with mitral S' wave (r = -0.41; P = .01) and mitral annular plane systolic excursion (r = -0.35; P = .05) but did not correlate with LV ejection fraction (r = -0.12; P = NS). GLS had the strongest accuracy for detecting LV fibrosis (area under the curve, 0.92). None of the echo parameters correlated with patient's exercise capacity. Conclusion: Global longitudinal strain is the most accurate LV global function measure that correlates with the extent of myocardial fibrosis in patients with advanced systolic HF requiring heart transplantation. © 2016 Elsevier Inc
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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