1,721,132 research outputs found
Prognostic role of pulmonary arterial capacitance in advanced heart failure.
No full textBackground—Right ventricular (RV) dysfunction frequently occurs and independently prognosticates in left-sided heart failure. It is not clear which RV afterload measure has the greatest impact on RV function and prognosis. We examined the determinants, prognostic role, and response to treatment of pulmonary arterial capacitance (PAC, ratio of stroke volume over pulmonary pulse pressure), in relation to pulmonary vascular resistance (PVR) in heart failure.
Methods and Results—We reviewed 724 consecutive patients with heart failure who underwent right heart catheterization between 2000 and 2005. Changes in PAC were explored in an independent cohort of 75 subjects treated for acute decompensated heart failure. PAC showed a strong inverse relation with PVR (r=−0.64) and wedge pressure (r=−0.73), and provides stronger prediction of significant RV failure than PVR (area under the curve ROC 0.74 versus 0.67, respectively, P=0.003). During a mean follow-up of 3.2±2.2 years, both lower PAC (P<0.0001) and higher PVR (P<0.0001) portend more adverse clinical events (all-cause mortality and cardiac transplantation). In multivariate analysis, PAC (but not PVR) remains an independent predictor (Hazard ratio=0.92 [95% CI: 0.84–1.0, P=0.037]). Treatment of heart failure resulted in a decrease in PVR (270±165 to 211±88 dynes·s–1·cm–5, P=0.002), a larger increase in PAC (1.65±0.64 to 2.61±1.42 mL/mm Hg, P<0.0001), leading to an increase in pulmonary arterial time constant (PVR×PAC) (0.29±0.12 to 0.37±0.15 second, P<0.0001).
Conclusions—PAC bundles the effects of PVR and left-sided filling pressures on RV afterload, explaining its strong relation with RV dysfunction, poor long-term prognosis, and response to therapy.M.D. is supported by a research grant from the Belgian American Educational Foundation (BAEF). W. H. W. T is supported by National Institutes of Health grants R01HL103931, P20HL113452 and the Cleveland Clinic Clinical Research Unit of the Case Western Reserve University Clinical and Translational Science Awards (UL1TR 000439-06)
Prognostic role of pulmonary arterial capacitance in advanced heart failure.
No full textBackground—Right ventricular (RV) dysfunction frequently occurs and independently prognosticates in left-sided heart failure. It is not clear which RV afterload measure has the greatest impact on RV function and prognosis. We examined the determinants, prognostic role, and response to treatment of pulmonary arterial capacitance (PAC, ratio of stroke volume over pulmonary pulse pressure), in relation to pulmonary vascular resistance (PVR) in heart failure.
Methods and Results—We reviewed 724 consecutive patients with heart failure who underwent right heart catheterization between 2000 and 2005. Changes in PAC were explored in an independent cohort of 75 subjects treated for acute decompensated heart failure. PAC showed a strong inverse relation with PVR (r=−0.64) and wedge pressure (r=−0.73), and provides stronger prediction of significant RV failure than PVR (area under the curve ROC 0.74 versus 0.67, respectively, P=0.003). During a mean follow-up of 3.2±2.2 years, both lower PAC (P<0.0001) and higher PVR (P<0.0001) portend more adverse clinical events (all-cause mortality and cardiac transplantation). In multivariate analysis, PAC (but not PVR) remains an independent predictor (Hazard ratio=0.92 [95% CI: 0.84–1.0, P=0.037]). Treatment of heart failure resulted in a decrease in PVR (270±165 to 211±88 dynes·s–1·cm–5, P=0.002), a larger increase in PAC (1.65±0.64 to 2.61±1.42 mL/mm Hg, P<0.0001), leading to an increase in pulmonary arterial time constant (PVR×PAC) (0.29±0.12 to 0.37±0.15 second, P<0.0001).
Conclusions—PAC bundles the effects of PVR and left-sided filling pressures on RV afterload, explaining its strong relation with RV dysfunction, poor long-term prognosis, and response to therapy.M.D. is supported by a research grant from the Belgian American Educational Foundation (BAEF). W. H. W. T is supported by National Institutes of Health grants R01HL103931, P20HL113452 and the Cleveland Clinic Clinical Research Unit of the Case Western Reserve University Clinical and Translational Science Awards (UL1TR 000439-06)
Determinants of dynamic changes in serum creatinine in acute decompensated heart failure: the importance of blood pressure reduction during treatment
No full textAims: ‘Worsening renal function’ (WRF) and ‘improvement in renal function’ (IRF) monitored by changes in serum creatinine are frequently encountered during treatment of acute decompensated heart failure (ADHF). We sought to establish the important haemodynamic determinants of alterations in serum creatinine.
Methods and results: We reviewed data from 443 patients treated for ADHF with haemodynamic guidance in a single centre. WRF and IRF were defined as a 25% increase or decrease in estimated glomerular filtration rate (eGFR) from time of admission to pulmonary artery catheter removal, respectively. Of the 443 patients, 46 (10%) experienced WRF and 127 (29%) had IRF. Baseline eGFR was lower in patients with IRF when compared with stable patients or those with WRF (45 ± 25 vs. 63 ± 30 vs. 68 ± 27 mL/min/m2, respectively, P < 0.0001). In contrast, the relative decrease in mean blood pressure (BP) was more pronounced in patients with WRF when compared with stable patients or those with IRF (15 ± 15 vs. 9 ± 17 vs. 4 ± 15%, respectively, P = 0.003). With larger decreases in mean BP, there was greater likelihood of experiencing WRF (P = 0.04) but less likelihood of experiencing IRF (P = 0.01). In contrast, the degree of changes in right atrial pressure or cardiac index did not affect the propensity for developing WRF or IRF. There was no difference in adverse clinical outcomes (death, heart transplantation, LV assist device implantation, or readmission) between the three groups (P = 0.56).
Conclusion: Blood pressure decrease, rather than alterations in cardiac output or central venous pressure, were associated with changes in serum creatinine during treatment of ADHF.M.D. is supported by a research grant from the Belgian American Educational Foundation (BAEF).
W.H.W.T. reports having received research grant support from Abbott Laboratories, and has served as a consultant for Medtronic Inc. and St Jude Medical. All other authors have no conflicts to declare
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
Percutaneous Mitral Valve Annuloplasty in Patients With Secondary Mitral Regurgitation and Severe Left Ventricular Enlargement
No full textVariations 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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