6,963 publications from this institution
<strong>Objectives:</strong> The aim of the present analysis is to compare the quantitative angiographic aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) among three balloon-expandable valves. <strong>Background:</strong> Quantitative videodensitometric aortography is an objective, accurate, and reproducible tool for adjudication of AR following TAVI. <strong>Methods:</strong> This is a retrospective corelab analysis, independent from industry, of aortograms from patients treated with TAVI using the balloon-expandable Myval transcatheter heart valve (THV) (Meril Life Sciences Pvt. Ltd., India), Sapien 3, and XT THVs (Edwards Lifesciences, Irvine, CA, USA). The study comprised of 108 analyzable aortograms from consecutive patients in a multicenter European registry who underwent Myval THV implantation. The results of quantitative assessment of AR in the Sapien 3 THV (n = 397) and Sapien XT THV (n = 239) were retrieved from a published pooled database. <strong>Results:</strong> The Myval THV had the lowest proportion of patients with moderate or severe angiographic quantitative AR (2.8%) compared to the Sapien 3 THV (8.3%; p = 0.049) and Sapien XT THV (10.9%; p = 0.012). Furthermore, the Myval THV had the lowest mean angiographic quantitative AR (6.3 ± 6.3%), followed by Sapien 3 THV (7.6 ± 7.1%) and Sapien XT THV (8.8 ± 7.5%), and it was significantly lower than that of the Sapien XT THV (p = 0.006), but not significantly different from Sapien 3 THV (p = 0.246). <strong>Conclusion:</strong> The Myval THV, in comparison with other BEV's analyzed in our database, showed a lower occurrence of moderate or severe AR after TAVI. These results should be confirmed in prospective cohorts of randomized patients with head-to-head THV comparisons.
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No abstract is provided for this article.
Of 1041 patients with consecutive aortocoronary bypass operations, 53 (5.1%) underwent reoperation during a mean follow-up time of three and a half years. The operative mortality of first operations was 1.2%, and of reoperations 3.8%. The anatomical reason for reoperation was failure of the bypass graft in 41 (77%) patients, which in 18 was accompanied by progression of disease. Progression alone was seen in seven (13%). When symptoms occurred within six months after the first operation, failure of the bypass graft(s) was nearly always found--in 32 out of 36 instances. Progression in non-bypassed arteries was seen only when symptoms occurred later. Late results in angina pectoris were less favourable in the group undergoing reoperation: 31 (65%) of the 48 operated on twice and 406 (46%) of the 877 patients operated on once still had angina at late follow-up. The same fraction in both groups was improved by operation: 88% versus 89%.
Under significant seismic loading conditions, the response of concentrically braced frames largely depends on the behaviour of the diagonal braces, which represent the key energy dissipating zones. Although the hysteretic response of steel braces under cyclic axial loading has been examined in previous studies, there is a need for further assessments that focus on quantifying failure. This paper describes the development of detailed finite-element models of hollow sections subjected to cyclic axial loading. The effects of initial imperfections and cyclic hardening are taken into consideration and the models are validated against data from 19 tests. A method to predict the fracture life of bracing members under cyclic loading is also described. Using the numerical models, parametric studies are undertaken to assess the influence of global and local slendernesses on the performance of the braces – both are found to affect the occurrence and severity of local buckling under cyclic loading, which causes high localised strains at the corner areas of sections, leading to fatigue fracture. A predictive equation addressing the coexisting influence of global slenderness and local slenderness on displacement ductility is presented. The observations in the current study are compared with conclusions from other experimental programmes, and the discrepancy between the findings is discussed.
Elliptical hollow sections have been recently added to the family of hot-finished tubular sections, featuring square, rectangular and circular hollow sections. Their usage has attracted considerable interest from industry, and significant recent research towards the development of comprehensive structural design rules has been carried out. Investigations have been performed at both cross-section and member levels and in a range of structural configurations. On the basis of full-scale tests, non-linear numerical simulations and experience gained from studies on other tubular sections, design rules for elliptical hollow sections have been developed. This paper describes the background to and validation of these rules, which include, at cross-section level, a set of slenderness parameters and classification limits for compression and bending, shear resistance formualtions and an interaction curve for combined shear and bending. At member level, column buckling curves have been proposed in harmony with those for structural steel circular hollow sections.