1,721,304 research outputs found
Late gadolinium enhancement as a potential marker of increased perioperative risk in aortic valve replacement
No full textOBJECTIVES: Risk assessment of patients with aortic stenosis (AS) undergoing aortic valve replacement (AVR) is challenging. We set out to determine the impact of myocardial late gadolinium enhancement (LGE), as detected by cardiovascular magnetic resonance (CMR), on postoperative outcomes following AVR.METHODS: A prospective observational study was conducted on patients undergoing CMR using the LGE technique within 1 year of subsequent AVR. Patients were categorized into absent, mid-wall or infarct patterns of LGE by independent observers blinded to all clinical data, and data were collected with regard to 30-day mortality, major adverse cardiac and cerebrovascular events (MACCE) and postoperative complications.RESULTS: A total of 63 patients were studied. Twenty-five patients had no LGE; 20 had mid-wall LGE and 18 had an infarct pattern. The incidence of MACCE, cerebrovascular accident (CVA) and heart block were significantly higher in the mid-wall group compared with the other two groups (MACCE: 25 vs. 0 vs. 5%, P = 0.014; CVA: 20 vs. 0 vs. 0%, P = 0.013; heart block: 30 vs. 4 vs. 12%, P = 0.050). Patients with no LGE had no 30-day MACCE events and no deaths up to 2 years of follow-up.CONCLUSIONS: The myocardial LGE holds promise as a means of predicting risk prior to AVR for AS
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
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
EACVI survey on standardization of cardiac chambers quantification by transthoracic echocardiography
Full text linkAIMS
To evaluate standard reporting of cardiac chambers size and function by transthoracic echocardiography (TTE), the EACVI Scientific Initiatives Committee performed a survey across European centres. In particular, the routine use of three-dimensional echocardiography (3DE) and speckle tracking-derived myocardial deformation imaging (STE) was explored.
METHODS AND RESULTS
A total of 96 European Echocardiography Laboratories from 22 different countries responded to the survey, which consisted of 20 questions. For most of the standard parameters of cardiac chamber size and function, answers from the centres were homogeneous and demonstrated good adherence to current recommendations. In particular, all centres assessed left ventricular (LV) and left atrial (LA) size combining diameter measurements with volumes obtained using the bi-plane Simpson's method. More variability was observed in the measurements of the right heart chambers and thoracic aorta. Interestingly, >90% of centres had access to 3DE and STE; however, the large majority of centres reserved the use of these techniques for selected cases, particularly for the measure of 3D LV volumes and ejection fraction and global longitudinal strain in patients being considered for cardiac device implantation, surgical intervention (valvular heart disease) or screened for cardiotoxicity. Only 10% of centres used 3DE for right ventricular and LA volumes. Also, <30% of the centres used LA strain imaging.
CONCLUSION
In Europe, a good adherence to current recommendations was observed for most of the standard parameters of cardiac chambers quantification by TTE. Advanced echocardiography modalities, such as 3DE and STE, are widely available but used only in selected cases
EACVI survey on the management of patients with patent foramen ovale and cryptogenic stroke
No full textAims The European Association of Cardiovascular Imaging (EACVI) Scientific Initiatives Committee performed a global survey to evaluate the current practice for the assessment and management of patients with suspected patent foramen ovate (PFO) and cryptogenic stroke.Methods and results In total, 79 imaging centres from 34 countries across the world responded to the survey, which comprised 17 questions. Most non-invasive investigations for PFO were widely available in the responding centres, with the exception of transcranial colour Doppler which was only available in 70% of sites, and most commonly performed by neurologists. Standard transthoracic echocardiography, with or without bubbles, was considered the first-level test for suspected PFO in the majority of the centres, whereas transoesophageal echocardiography was an excellent second-level modality. Most centres would rule out atrial fibrillation (AF) as a source of embolism in all patients with cryptogenic stroke (63%), with the remainder reserving investigation for patients with multiple AF risk factors (33%). Cardiac magnetic resonance was the preferred tool for identifying other unusual aetiologies, like cardiac masses or thrombi. After PFO closure, there was variation in the use of antiplatelet therapy: a quarter recommended treatment for life, while only 12% recommended 5 years as stipulated in the guidelines (12%). Antibiotic prophylaxis prior to dental or endoscopic procedures was not recommended in 41% of centres, contrary to what the guidelines recommended.Conclusion Our survey revealed a variable adherence to the current recommendations for the diagnosis and management of patients with cryptogenic stroke and PFO. Efforts should focus on optimizing and standardizing diagnostic tests and treatment of this condition
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
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