1,720,971 research outputs found
Morphological modification of the aortic annulus in tricuspid and bicuspid valves after aortic valve reimplantation: an electrocardiography-gated computed tomography study
Full text linkAortic valve-sparing operations have been shown to produce fewer valve-related complications than valve replacement. The aortic root is a morphological and functional unit in which the annulus plays an important role on dynamism, shape and geometry of the valve with different results in bicuspid aortic valves (BAVs) or tricuspid aortic valves (TAVs). The aim is to evaluate the differences in the size and shape of the aortic annulus between native BAVs and TAVs using ECG-gated computed tomography (CT) after a reimplantation procedure
Optimized use of the "skirt" of the Valsalva graft for the completion Bentall
No full textWe report the case of a patient with an aortic root aneurysm who had previously undergone aortic valve replacement with a large mechanical prosthesis which proved to be normally functioning at the time of reoperation. We describe a new technique of replacing the aortic root while retaining the existing aortic valve similar to the "completion Bentall" procedure using a 32 mm Valsalva graft by suturing the skirted portion of the graft to the sewing ring of the mechanical valve. The ability of the skirt to increase its diameter was the key of this approach
Twenty-year experience of aortic valve reimplantation using the Valsalva graft
No full textObjective: Over the past 20 years valve-sparing aortic root replacement has aroused increasing interest because of a progressive attitude towards the preservation of natural tissue. Aortic reimplantation is the most used technique to spare the valve, allowing simultaneously aortic root replacement and aortic annular stabilization. The reimplantation into a graft with sinuses guarantees an optimal anatomic and functional reconstruction with established good results at 15 years. The aim of this study is to report the world longest follow-up (up to 20-years) of aortic valve reimplantation using the Valsalva graft. Methods: From February 2000 to December 2021, 265 consecutive patients with aortic root aneurysm received aortic valve reimplantation using the Valsalva graft. From 2018 leaflet plication with the routine use of caliper was performed. For each patient we performed both intraoperative and post-procedural transoesophageal echocardiography. All patients were followed with clinical assessment and echocardiography. The mean duration of follow-up was 85 ± 63 months. Results: The study cohort had a median age of 55 ± 18 and 87.2% were male. The aortic root aneurysm was associated to bicuspid aortic valve in 18.9% of patients and to Marfan syndrome in 10.6% of cases. 55.9% had an aortic regurgitation ≥ 2+. Overall survival at 15 was 87.6 ± 3.4. Freedom from cardiac death was stable at 99.6 ± 0.4 at 5, 10 and 15 years. Freedom from recurrent AR ≥ 3+ and freedom from reoperation remained stable at 10 and 15 years at 92.2 ± 2.1 and 95.9 ± 1.6, respectively. There was a minimal incidence of infective endocarditis (0.8%), thromboembolism (2.2%) and haemorrhage (2.0%). Six out of seven patients requiring reoperation had surgery in the first period of our experience (last in 2004). Early sub-optimal results had a negative effect on residual aortic regurgitation. Moreover, we hypothesized that the routine use of caliper may have contributed to a further improvement of the outcome, even if these data need to be confirmed by a longer follow-up. Conclusions: The first long term follow-up after aortic valve reimplantation using the Valsalva graft demonstrated excellent results. These long-term results gradually improved with learning curve, remaining stable during the second decade of observation. The systematic use of caliper may have contributed to a further improvement of the outcome
A new method for artificial chordae length “tuning” in mitral valve repair: Preliminary experience
No full textObjectives
Implanting expanded polytetrafluoroethylene neochordae is an established technique in treating complex mitral regurgitation. Difficulty in obtaining reliable preoperative and intraoperative measurements of an ideal neochordae length, as well as the unfeasibility of adjusting lengths once set in place with traditional techniques, led us to develop a system that allows rapid change of length after the evaluation of valve continence with hydrostatic tests.
Methods
The system consists of two components: a papillary component with arrest knots at constant intervals and a leaflet component with a reversible noose-lace to fix the loop to 1 of the knots on the papillary component. After implantation and coupling of the two components at a presumable optimal length, a prosthetic ring is sutured in place. Hydrostatic testing is then performed. Optimal chordae length can be obtained by releasing the noose-lace and sliding it over another fixing-knot. The adjustment can be performed as often as required without placing stress on the anatomic structures.
Results
Twenty patients underwent repair with this technique. No deaths or major adverse events occurred. All patients underwent echocardiography, both at discharge and 6 months after the operation. A total of 14 patients had no residual insufficiency, 5 patients had mild or trivial postoperative insufficiency without progression of regurgitation at the sixth month, and only 1 patient had mild insufficiency at discharge progressing to moderate insufficiency at the sixth month.
Conclusion
This new technique facilitates an otherwise complicated procedure. Short-term results are satisfactory, but further follow-up is require
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
- …
