1,720,976 research outputs found
Preventive left main and right coronary artery stenting to avoid coronary ostia occlusion in high-risk stentless valve-in-valve transcatheter aortic valve implantation
No full textTranscatheter aortic valve implantation is becoming an attractive and promising alternative to redo surgery for aortic bioprosthetic valves degeneration, especially in high-risk patients. However, valve-in-valve transcatheter aortic valve implantation itself carries some procedural risks and potential challenges that interventionists must be aware of. An accurate preprocedural planning is fundamental for the prevention of potentially fatal complications. This case describes a novel strategy of simultaneous right and left coronary artery stenting preventing bilateral coronary obstruction in a patient with a stentless surgical aortic valve and extremely low origin of the 2 coronary arteries
The relationship between serum potassium levels and cardiac arrhythmias in left ventricular assist device (LVAD) recipients: a comprehensive analysis and prognostic evaluation
No full textBackgroundThis study aimed to comprehensively analyze the relationship between serum potassium (K+) levels and the risk of de novo cardiac arrhythmias in left ventricular assist device (LVAD) recipients.MethodsWe performed a retrospective study using the INTERMACS registry. Data was collected on adult patients with available K+ measurements taken 1-month post-LVAD implantation. K+ levels were the main exposure of interest and were analyzed as a continuous and categorical variable (quartiles of baseline K+ distribution). The main outcome of interest was the occurrence of de novo arrhythmia events, either sustained (ventricular [VA] or supraventricular arrhythmia [SVA]) or not sustained (atrial fibrillation/flutter [AF]). All-cause mortality was evaluated as the secondary outcome. Multivariable adjusted time-dependent Cox regression models and natural splines were used to describe the relationship between the exposure and outcomes of interest.Results10,570 patients met our inclusion criteria. A significant and consistent relationship was observed between the lowest quartile of longitudinal K+ and the risk of arrhythmic events (HR 1.28, 95% CI 1.08, 1.53, p = 0.005) as well as in the highest K+ quartile (HR 1.24, 95% CI 1.02, 1.49, p = 0.027).A similar relationship was confirmed in the stratified analysis of arrhythmia types for SVAs and AF. The data were reflected in a U shaped relationship. Similarly, the highest and lowest quartiles of longitudinal K+ were independently associated with a significant increase in the HR of death, which was reflected by a U shaped relationship.Results10,570 patients met our inclusion criteria. A significant and consistent relationship was observed between the lowest quartile of longitudinal K+ and the risk of arrhythmic events (HR 1.28, 95% CI 1.08, 1.53, p = 0.005) as well as in the highest K+ quartile (HR 1.24, 95% CI 1.02, 1.49, p = 0.027).A similar relationship was confirmed in the stratified analysis of arrhythmia types for SVAs and AF. The data were reflected in a U shaped relationship. Similarly, the highest and lowest quartiles of longitudinal K+ were independently associated with a significant increase in the HR of death, which was reflected by a U shaped relationship.ConclusionsOur study reveals a significant U shaped relationship between low and high K + levels and cardiac arrhythmias in LVAD patients, particularly SVAs and AF. Both high and low K + levels negatively impacted patient survival
Age- and sex-tailored serum phosphate thresholds do not improve cardiovascular risk estimation in CKD.
No full textBACKGROUND: Disordered metabolism of phosphorus is one of the hallmarks of chronic kidney disease (CKD), resulting in increased cardiovascular morbidity and mortality. Age and sex may affect the metabolism of phosphorus and subsequently its serum level. We evaluated if age- and sex-specific cutoffs for hyperphosphatemia may define cardiovascular risk better than the current guideline cutoffs.
METHODS: We used data from 16,834 subjects participating in the 1999-2006 National Health and Nutrition Examination Survey (NHANES); the prevalence of self-reported cardiovascular disease (CVD) and mortality rates were analyzed in CKD patients for both the classic definitions (CH; i.e., NKF-KDOQI and K-DIGO) and a tailored definition (TH) of hyperphosphatemia by means of regression models adjusted for age, sex, race/ethnicity, smoking status and body mass index. The cutoffs for TH were represented by the 95th percentile of an age- and sex-matched non-CKD population.
RESULTS: Serum phosphorus levels showed an inverse correlation with age (r = -0.12; p<0.001); females showed higher levels than males (3.78 ± 0.54 mg/dL vs. 3.62 ± 0.58 mg/dL; p<0.001). Even if the association between the TH definition and CVD was marginally better compared with the CH definition (odds ratio [OR] = 1.49, 95% confidence interval [95% CI], 1.04-2.13; p=0.030 vs. OR=1.55, 95% CI, 0.98-2.44; p = 0.059), the TH model was not superior in predicting CVD or mortality.
CONCLUSIONS: Our data suggest that a tailored, age- and sex-specific definition of hyperphosphatemia is not superior to conventional definitions in predicting cardiovascular events in patients with CKD
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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