1,721,014 research outputs found
Isolated coronary artery aneurysms presenting with ST-elevation myocardial infarction – a case of when less is more
No full textIschemic preconditioning—an unfulfilled promise
No full textMyocardial reperfusion injury has been identified as a key determinant of myocardial infarct size in patients undergoing percutaneous or surgical interventions. Although the molecular mechanisms underpinning reperfusion injury have been elucidated, attempts at translating this understanding into clinical benefit for patients undergoing cardiac interventions have produced mixed results. Ischemic conditioning has been applied before, during, or after an ischemic insult to the myocardium and has taken the form of local induction of ischemia or ischemia of distant tissues. Clinical studies have confirmed the safety of differing conditioning techniques, but the benefit of such techniques in reducing hard clinical event rates has produced mixed results. The aim of this article is to review the role of ischemic conditioning in patients undergoing percutaneous and surgical coronary revascularization
The assessment of ischaemic burden:validation of a functional jeopardy score against cardiovascular magnetic resonance perfusion imaging
No full textAims: This study assesses the relationship between classical anatomical jeopardy scores, functional jeopardy scores (combined anatomical and haemodynamic data), and the extent of ischaemia identified on cardiovascular magnetic resonance (CMR) perfusion imaging. Methods and results: In 42 patients with stable angina and suspected coronary artery disease (CAD), CMR perfusion imaging was performed. Fractional Flow Reserve (FFR) was measured in vessels with ≥50 % stenosis. The APPROACH and BCIS jeopardy scores were calculated based on QCA results with both a 70 % (APP70 and BCIS70) and a 50 % stenosis (APP50, and BCIS50) used as the threshold for significance, as well as after integration of FFR and compared with the extent of ischaemia identified on CMR. The correlation between the extent of ischaemia measured by CMR and the anatomical jeopardy scores was moderate (APPROACH: r = 0.58; BCIS: r = 0.48, p = 0.001). Integrating physiological information improved this significantly to r = 0.82, p = 0.0001 for APPROACH and r = 0.82, p = 0.0001 for BCIS scores (z-statistic = −2.04, p = 0.04; z-statistic = −2.63, p = 0.009). In relation to CMR, the APPROACH and BCIS scores overestimated the volume of ischaemic myocardium by 29.2 and 25.2 %, respectively, which was reduced to 12.8 and 12 % after integrating functional data. Conclusions: Anatomical and functional jeopardy scores overestimate ischaemic burden when compared to CMR. Integrating physiological information from FFR to generate a functional score improves ischaemic burden estimation.</p
Physiology-guided management of serial coronary artery disease a review
No full textImportance: Ischemia-guided revascularization is the cornerstone of contemporary management of coronary artery disease and has evolved from noninvasive functional evaluation to real-time assessment with invasive physiological indices during diagnostic catheterization. However, serial/diffuse disease is common, and revascularization decisions often need to be made about individual lesions within the same vessel. It is unclear whether current physiological techniques, such as fractional flow reserve, can be reliably used to discern the individual contribution of lesions within a serially diseased vessel with erroneous measurements, potentially leading to suboptimal revascularization decisions. This review addresses the application of physiological techniques to serial coronary disease, highlighting challenges and potential solutions.Observations: Physiological indices, such as fractional flow reserve, are well validated and correlated with clinical outcomes; however, the challenging physiology of serial stenoses makes it difficult to apply conventional techniques to identify the physiological significance of individual lesions. The 2 methods are most accurate in assessing serial disease are the manual pullback, with treatment of the greatest pressure gradient, or adopting the use of a large disease-free side branch to isolate the significance of the proximal lesion in the context of serial disease involving the left main coronary artery. In addition, resting indices, such as instantaneous wave-free ratio, have theoretical benefits that may make them more reliable in serial disease, with further data awaited.Conclusions and Relevance: Serial coronary artery disease is common, and physiological assessment is prone to errors. The future, whether it be in improving the interpretation of fractional flow reserve, using resting indices such as instantaneous wave-free ratio, or examining novel flow-based resistance indices, will hopefully improve our management of this common yet unresolved clinical conundrum. In the meantime, revascularisation decisions in this challenging scenario should focus on clinical presentation and physiologic evaluation using a pressure-wire pullback maneuver and left main disease-free side branch where appropriate.</p
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
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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