1,720,961 research outputs found
Unveiling the limitations of non-metabolic thresholds in assessing maximal effort: The role of cardiopulmonary exercise testing
No full textIntroduction: Maximal effort, defined by a respiratory exchange ratio (RER) ≥ 1.10, is crucial for accurate interpretation of cardiopulmonary exercise testing (CPET). Standard tests rely on non-metabolic thresholds, such as peak predicted heart rate (ppHR) ≥ 85 %, double product (DP) ≥ 20,000 bpm*mmHg and peak metabolic equivalent of task (MET) ≥ 5.0. This study aimed to assess the effectiveness of non-metabolic thresholds in detecting maximal effort, compared with the RER ≥ 1.10 criterion. Methods: We retrospectively analyzed stable patients who underwent CPET from 2022 to 2023, regardless of test indication, history of heart failure (HF), or medication use. All patients also performed transthoracic echocardiography. Results: Among 239 middle-aged patients (53 ± 14 years, 67 % male), 86 % achieved a RER ≥ 1.10, and 65 % had a diagnosis of HF. Non-metabolic thresholds correctly identified maximal efforts (RER ≥ 1.10) in 75 % of the cases (AUC < 0.600). Misclassified cases were more likely to have a history of atrial fibrillation (AF), paced rhythm, HF, and beta-blockers or RAAS inhibitors use. These patients exhibited lower VO2 peak and higher VE/VCO2 slope. Multivariable analysis identified HF history (OR 4.8, CI 95 % 1.6–15.6, p: 0.005), low resting DP (≤ 7500 mmHg*bpm), and ramp protocol as independent predictors of discordant tests. Conclusion: Non-metabolic thresholds misclassified up to 25 % of tests with RER ≥ 1.10 as non-maximal, potentially leading to inaccurate interpretation. In patients with HF, poor expected functional capacity and low DP, direct referral to CPET-equipped facilities may provide more accurate assessment than relying on non-metabolic thresholds
Double versus single source left-sided coronary revascularization using bilateral internal thoracic artery graft alone
No full textLeft-sided coronary revascularization with bilateral internal thoracic artery (BITA) graft is performed usually either with an in situ (double source) or Y-graft configuration (single source). Two hundred fifty-three (mean age, 67.1 ± 9.5 years) patients underwent isolated left-sided coronary revascularization with BITA graft alone at the present authors' institution (2000-2015). Skeletonized BITA grafts were used either in an in situ (n = 199) or Y-graft configuration (n = 54). Forty pairs were identified with the propensity score-matching. Outcomes of the two groups were compared both in unmatched and matched series. Cardiopulmonary exercise testing was performed in five pairs of selected, asymptomatic matched patients having patent BITA grafts at coronary computed tomography angiography. BITA in situ patients had lower risk profiles than BITA Y-graft patients (median EuroSCORE II, 1.9 vs. 2.9%, p = 0.051). In-hospital mortality (5.6 vs. 0, p = 0.0093) and the rates of postoperative complications except deep sternal wound infection were higher in BITA Y-graft patients. However, these differences were not confirmed in matched groups. During the follow-up period (mean, 5.9 ± 4.3 years), between BITA in situ and BITA Y-graft matched patients, there were no differences in non-parametric estimates of freedom from cardiac death (p = 0.6), major adverse cardiac and cerebrovascular events (MACCEs, p = 0.65), and repeat coronary revascularization (p = 0.44). Adjusted risk estimates of MACCEs according to BITA configuration confirmed no superiority of the one configuration over the other (p ≥ 0.44). No significant differences were found at the cardiopulmonary exercise testing. Results of left-sided coronary revascularization with BITA graft alone are independent from BITA configuration, even after stress testing
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
Left ventricular thrombectomy in myocarditis: the epicardial scan & video-assisted transaortic approach
No full textIn a 23-year-old man having myocarditis in the context of eosinophilic granulomatosis with polyangiitis, a mobile left ventricular apical thrombus was found with transthoracic echocardiography. Its surgical removal was established because there were no signs of resizing after effective intravascular anticoagulation therapy. Surgery was carried out via a median sternotomy with cardiopulmonary bypass. The site of endocardial implantation of the thrombus was identified with epicardial ultrasonography scan. The trans-aortic approach was adopted to avoid complications such as ventricular dysfunction and arrhythmias secondary to ventricular incision. Real-time imaging of the complete removal was obtained with optical instruments
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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