1,720,998 research outputs found
Unusual case of severe aortic regurgitation in a child with bicuspid aortic valve
Full text linkAortic regurgitation (AR) is common after aortic balloon valvuloplasty in children and it has been associated with large balloon/annulus ratio, abnormal valve morphology and aortic valve prolapse. We present a rare case of severe AR after aortic balloon valvuloplasty due to aortic strands rupture, causing prolapse of the co-joined cusp. These findings were identified by 3D echocardiography, highlighting the importance of this imaging technique even in pediatric patients
Maternal cardiovascular adaptation to pregnancy in obese pregnant women
No full textIntroduction Obesity is known to be associated with cardiovascular compromise and a major risk factor for the development of hypertensive disorders in pregnancy. However, little is known about the effect of obesity on maternal cardiac function. The aim of this study was to investigate the effect of obesity on the maternal cardiovascular system.Material and methods This was a prospective, observational, longitudinal study. Pregnant women with booking body mass index (BMI) >= 30 kg/m(2 )were compared with pregnant women with normal booking BMI 20-24.9 kg/m(2). Participants were seen at three time points during pregnancy; 12-14, 20-24 and 30-32 weeks. At all visits, maternal blood pressure (BP) was measured, and cardiac geometry and function were assessed using two-dimensional trans-thoracic echocardiography. Multilevel linear mixed-effects models were used for all the comparisons.Results Fifty-nine pregnant women with obesity were compared with 14 pregnant women with normal BMI. In women with obesity, the maternal BP, heart rate and cardiac output were higher and peripheral vascular resistance was lower (p < 0.01 for all comparisons) compared with normal BMI women. Women with obesity had altered cardiac geometry with higher left ventricular end diastolic diameter, intraventricular septal thickness, posterior wall diameter, relative wall thickness and left ventricular mass (p < 0.001 for all comparisons). There was also evidence of impaired diastolic indices in the obese group with a lower E/A ratio, tissue Doppler imaging E' lateral and medial and higher left atrial volume (p < 0.01 for all comparisons). Finally, women with obesity had reduced longitudinal function, as assessed by mitral plane annular systolic excursion, between the second and third trimester of pregnancy, indicating possible early cardiac dysfunction in this group.Conclusions Obesity is associated with maternal hyperdynamic circulation, altered cardiac geometry and suboptimal diastolic function, compared with normal BMI pregnant women, and these factors may contribute to the increased risk of complications in obese pregnant women
A Rodent Model of The Ross Operation: Syngeneic Pulmonary Artery Graft Implantation in A Systemic Position
No full textThe Ross operation for aortic valve disease has regained new interest due to its outstanding long-term results. Nonetheless, when employed as freestanding root replacement, the possible dilation of the pulmonary autograft and subsequent aortic regurgitation is described. Several animal models have been proposed. However, these are usually limited to ex-vivo models or in-vivo experiments with relatively expensive large animal models. In this study, we sought to establish a rodent model of pulmonary artery graft (PAG) implantation in a systemic position. A total of 39 adult Lewis rats were included. Immediately after euthanasia, the pulmonary root was harvested from a donor animal (n=17). Syngeneic recipient (n=17) and shamoperated (n=5) rats were sedated and ventilated. In the recipient group, the PAG was implanted with an end-to-end anastomosis in infra-renal abdominal aortic position. Sham-operated rats underwent only transection and re-anastomosis of the aorta. Animals were followed with serial ultrasound studies for two months and post-mortem histological analysis. The median PAG diameter in the native position was 3.20 mm (IQR=3.18-3.23). At follow-up, the median diameter of the PAG was 4.03 mm (IQR=3.74-4.13) at 1 week, 4.07 mm (IQR=3.80-4.28) at 1 month, and 4.27 mm (IQR=3.90-4.35) at 2 months (p<0.01). Peak systolic velocity was 220.07 mm/s (IQR=210.43-246.41) at 1 week, 430.88 mm/s (IQR=375.28-495.56) at 1 month, and 373.68 mm/s (IQR=305.78-429.81) at 2 months (p=0.02) and did not differ from the sham-operated group at the end of the experiment (p=0.5). Histological analysis did not show any sign of endothelial thrombosis. This study showed that rodent models may allow for the evaluation of the long-term adaptation of the pulmonary root to a high-pressure system. A systemically placed syngeneic PAG implantation represents a simple and feasible platform for the development and evaluation of novel surgical techniques and drug therapies to further improve the outcomes of the Ross operation
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
The Sub-Pulmonary Left Ventricle in Patients with Systemic Right Ventricle, the Paradoxical Neglected Chamber: A Cardiac Magnetic Resonance Feature Tracking Study.
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