1,720,956 research outputs found
Mitral annulus calcification: determinants of repair feasibility, early and late surgical outcome
No full textObjective: The aim of this study was to determine the factors influencing the feasibility of valve repair and the surgical outcome in patients with mitral annulus calcification. Methods: In 124 patients with mitral annulus calcification undergoing surgery, two entities were distinguished: Barlow disease (myxomatous leaflets, n = 60) and fibroelastic deficiency (FED) (normal leaflets, n = 64). The calcification score was lower (1.9 vs 2.8); the annulus was more dilated (ring 35 vs 32 mm) and ruptured chordae were more frequent (77% vs 37%) in Barlow than in FED (p < 0.001). The clinical profile was different: age (60 +/- 14 vs 73 +/- 8 years, p < 0.001), systemic hypertension (22% vs 70%, p < 0.001), chronic renal insufficiency (5% vs 22%, p < 0.01), cancer (7% vs 25%, p < 0.01). Multifocal atherosclerosis was less frequent in Barlow than in FED: carotid disease (17% vs 54%, p < 0.001), aortic atheroma (21 % vs 51 %, p < 0.001) and coronary disease (22% vs 56%, p < 0.01). Echocardiography showed two different patterns in Barlow and FED: aortic valve stenosis (1.7% vs 31%), left atrial diameter (54 vs 49 mm), left ventricular end-diastolic diameter (62 vs 54 mm), interventricular septal thickness (11 vs 13 mm), and systolic pulmonary pressure (40 vs 56 mmHg), respectively (p < 0.001). Bacterial endocarditis was observed in 24 cases (19%). Results: The surgical technique was a valve repair in 68% and a replacement in 32%. The repair rate depended upon the extent of annulus calcifications (p < 0.001) and the type of degenerative disease (95% vs 44% in Barlow and FED p < 0.001). In-hospital mortality was 14% (Barlow: 5% vs FED: 23%, p < 0.01). The mean follow-up was 50 t 41 months. Overall 5-year year survival was 76% (Barlow: 90% vs FED: 64%, p < 0.001) and survival free from cardiac event was 69% at 5 years (Barlow: 87% vs FED: 52%, p < 0.001). Five-year survival was higher following repair than replacement (84% vs 64% p < 0.001). Chronic renal insufficiency and bacterial endocarditis were two predictors of early and late death (p < 0.01). Conclusions: The aetiopathogeny of the degenerative mitral disease responsible for annulus calcifications corresponded to distinct anatomical, clinical and echographic patterns. It was a main determinant of repair feasibility, early and late surgical outcom
Surgery for infective endocarditis on mitral annulus calcification
No full textBackground and aim of the study: The study aim was to assess the characteristics of bacterial endocarditis complicating mitral annulus calcification, and to evaluate the surgical results.
Methods: Twenty-four patients (mean age 64 years) underwent surgery for mitral insufficiency secondary to mitral endocarditis with annulus calcification (acute, n = 18; healed, n = 6). Surgery was performed as an emergency in seven cases for septic (n = 3) or cardiogenic (n = 4) shock. An aortic prosthesis had previously been placed in three cases. Comorbidities noted included chronic renal insufficiency/dialysis (n = 8), cancer (n = 6), coronary disease (n = 6), and obstructive cardiomyopathy (n = 1). Nine patients suffered an embolic complication, such as stroke (n = 7, of which three had coma), splenic (n = 3), or lower limb (n = 1). The microorganism present was identified as Staphylococcus aureus (n = 9), Streptococcus/Enterococcus sp. (n = 12), or others (n = 3). The left atrial diameter was 48 mm, the ejection fraction 63%, and the septal thickness 13 mm.
Results: The mean severity score of annulus calcifications (range: 1 to 5) was 1.9. The anatomical lesions included: vegetations (n = 16, of which eight were >10 mm), leaflet perforation (n = 9), chordae rupture (n = 9), aortic abscess (n = 2) and mitral annular abscess (n = 9), and one fistulation into the pericardium. The valve was repaired in 15 cases, and replaced in nine (seven bioprostheses, two mechanical). Associated procedures included aortic valve replacement (n = 7) and coronary artery bypass (n = 3). The in-hospital mortality was 29% (n = 7); all patients who died were operated on during the acute phase. All patients who presented with septic shock or coma died. After a mean follow up of 46 months, six patients had died (overall survival was 46% at 33 months), and 11 were in NYHA class I/II. One recurrence of endocarditis was treated medically.
Conclusion: Bacterial endocarditis complicating mitral annulus calcification has a poor prognosis due to the frequent comorbidity and severity of the infectious complications. Patients in septic shock or coma do not appear to be suitable candidates for surgery. Valve repair was possible in two-thirds of the present patients; otherwise, a bioprosthetic replacement was the option of choice
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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