1,720,971 research outputs found
New insights into regional systolic and diastolic left ventricular function with tissue Doppler echocardiography: From qualitative analysis to a quantitative approach
No full textTissue Doppler echocardiography is a variation of conventional Doppler now imaging. This modality allows quantification of the Doppler shift within the range of myocardial tissue motion The velocity at a variety of myocardial sites can be determined and distinguished very rapidly by using Doppler techniques. The velocity of moving tissue can be studied with pulsed wave tissue Doppler sampling, which displays the velocity of a selected myocardial region against time, with high temporal resolution. In addition, the velocities can be calculated with time-velocity maps and displayed as color-encoded velocity maps in either an M-mode or 2-dimensional format. This review will focus on the technical aspects and the different methods of tissue Doppler echocardiography for the analysis of regional systolic and diastolic left ventricular function. Whereas pulsed wave tissue Doppler echocardiography allows measurements of velocities of a selected myocardial region, color tissue Doppler gives the best overview of cardiac dynamics because the entire scanned color data are displayed simultaneously. However,there is an increasing need for objective evaluation of tissue Doppler information Digital images and postprocessing of the data allow for quantitative off-line analysis, and the different approaches and parameters proposed from different centers are discussed
How-to: Focus Cardiac Ultrasound in acute settings
No full textFocus cardiac ultrasound (FoCUS) provides vital information at at the bedside which has the potential of improving outcomes in the acute settings. FoCUS could help the clinicians in their daily clinical decision-making while applied within the clinical context as an extension of bedside clinical examination. FoCUS practitioners should be aware of their own limitations with the importance of the timely referral for comprehensive Echocardiography whenever required
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
Evaluation of ventriculo-arterial coupling in ST elevation myocardial infarction with left ventricular dysfunction treated with levosimendan
No full textBackground: Acute heart failure (AHF) after ST-segment elevation myocardial infarction (STEMI) is usually treated with inotropic support or vasoactive medications. In this study, we aimed at investigating the role of levosimendan on cardiovascular determinants of contractility and afterload in patients with AHF following STEMI treated with percutaneous coronary intervention (PCI). Methods: Forty-eight consecutive STEMI patients were retrospectively enrolled. Non-invasive assessment of left ventricular elastance (Ees) and arterial elastance (Ea) and their relationship, ventriculo-arterial coupling (VAC) was performed before and after levosimendan infusion. Results: After infusion of levosimendan a significant increase in SV was detected in all patients (from 48 ± 17 to 60 ± 21 ml, p < 0.001). VAC slightly decreased from 1.74 ± 0.8 to 1.66 ± 0.7 (p = NS) as a result of a profound reduction in arterial elastance (Ea 2.34 ± 1.09 to 1.74 ± 0.5 mm Hg/ml, p < 0.001) and in ventricular elastance (Ees 1.57 ± 0.12 to 1.24 ± 0.09 mm Hg/ml, p = 0.021). Ejection fraction (EF) (from 0.29 ± 0.1 to 0.32 ± 0.1, p < 0.01) and WMSI, (from 2.16 ± 0.47 to 2.05 ± 0.54, p < 0.05) also, significantly improved. Finally, baseline VAC was able to predict the use of norepinephrine (NE) and early and one-year mortality of patients treated. Conclusion: In STEMI patients with AHF the use of levosimendan significantly increases stroke volume after 24-hour treatment through Ea reduction. Baseline VAC seemed to predict early and late mortality and early and prolonged use of NE, however, this needs to be tested in larger series of patients and multivariate adjustments for other prognostic predictors
Ventriculo-arterial coupling in the intensive cardiac care unit: a non-invasive prognostic parameter
No full textAims: The aim of this study was to investigate the relationship between ventriculo-arterial coupling (VAC) and in-hospital outcomes and to assess the prognostic value of VAC in critically ill patients. Methods and results: A total of 329 consecutive patients (mean age 66,7 ± 15.5 years, 66.9% male) admitted to the intensive cardiac care unit of the Sandro Pertini Hospital, Rome (Italy) between January 2019 and December 2019, were included in the study. All patients underwent blood pressure measurement and non-invasive, echocardiography-derived estimates of left ventricular end-systolic elastance (Ees), arterial elastance (Ea) and VAC in a single-beat determination using the iElastance© application. In-hospital events related to acute heart failure and hypoperfusion were recorded and need for invasive ventilation, intra-aortic balloon pump, renal replacement therapy and death were considered as composite. Overall, 39 patients (11,8%) experienced in-hospital complications (group C), and 290 (88,2%) did not (group NoC). Ea and VAC were found to be significantly higher in group C than in group NoC, and a trend toward decreased Ees was observed in group C. VAC was a strong and independent predictor of in-hospital clinical outcome both at univariable and multivariable analysis adjusted for comorbidities [OR (95% CI): 1.868 (1.141-3.059); P = 0.013] and hemodynamic parameters [OR (95% CI): 1674 (1018-2755); P = 0.042]. Conclusion: VAC might be an additional non-invasive prognosticator of outcome in critically ill patients
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
