6,963 publications from this institution
An energy formulation employing total potential energy principles is presented to derive a governing equation for strength predictions of struts made from materials following the Ramberg–Osgood constitutive law such as stainless steel, cold-formed steel, and aluminium alloys. The formula is generic and applicable to arbitrary cross-sections and all strut slendernesses for which flexural buckling is critical. Extensive comparisons against experimental data on square and rectangular hollow section struts as well as finite element simulations demonstrate the accuracy of the developed formula, while the effect of varying material parameters is examined through comprehensive parametric studies. Owing to its simplicity and its derivation based on mechanical principles, arbitrary configurations of material parameters and cross-sections can be analysed, making the formula suitable for use in design practice, representing effectively a non-iterative alternative to the widely accepted design load employing the tangent modulus. With the aid of the formula, new column buckling design provisions are developed, which show excellent agreement with experimental data and meet the reliability requirements specified within the structural Eurocodes.
Mitral regurgitation (MR) is a common disease in developed countries, affecting an estimated 9.3% of the population aged ≥75 years. Although surgical valve repair or replacement is currently the “gold standard” treatment for severe symptomatic MR, almost one-half of the patients are denied surgery. These are usually older patients with moderate left ventricular dysfunction and several non-cardiac co-morbidities. The aim of transcatheter mitral valve repair is to provide a treatment that is at least as effective as conventional valve surgery, and is associated with less morbidity and mortality. Currently an important number of devices are under evaluation, and can be categorized according to the treatment strategy.... (excerpt)
No abstract is provided for this article.
Background Data on optimal antiplatelet treatment regimens in patients who undergo multivessel percutaneous coronary intervention (PCI) are sparse. Objectives This post hoc study investigated the impact of an experimental strategy (1-month dual antiplatelet therapy [DAPT] followed by 23-month ticagrelor monotherapy) versus a reference regimen (12-month DAPT followed by 12-month aspirin monotherapy) according to multivessel PCI. Methods The GLOBAL LEADERS trial is a prospective, multicenter, open-label, randomized controlled trial, allocating all-comer patients in a 1:1 ratio to either the experimental strategy or the reference regimen. The primary endpoint was the composite of all-cause death or new Q-wave myocardial infarction at 2 years. The secondary safety endpoint was Bleeding Academic Research Consortium type 3 or 5 bleeding. Results Among the overall study population (n=15,845), 3,576 patients (22.4%) having multivessel PCI experienced a significantly higher risk of ischemic and bleeding events at 2 years, compared to those having single-vessel PCI. There was an interaction between the experimental strategy and multivessel PCI on the primary endpoint (hazard ratio: 0.62; 95% confidence interval: 0.44 to 0.88; pinteraction = 0.031). This difference was largely driven by a lower risk of all-cause mortality. In contrast, the risk of Bleeding Academic Research Consortium type 3 or 5 bleeding was statistically similar between the 2 regimens (hazard ratio: 0.92; 95% confidence interval: 0.61 to 1.39; pinteraction = 0.754). Conclusions Long-term ticagrelor monotherapy following 1-month DAPT can favorably balance ischemic and bleeding risks in patients with multivessel PCI. These findings should be interpreted as hypothesis-generating and need to be replicated in future dedicated randomized trials. (GLOBAL LEADERS: A Clinical Study Comparing Two Forms of Anti-platelet Therapy After Stent Implantation; NCT01813435).
1. Intracoronary Brachytherapy: A New Treatment for the Prevention of Restenosis 2. Therapeutic Angiogenesis for Coronary Artery Disease 3. Spot Stenting 4. Ostial and Bifurcation Disease 5. Left Main Disease 6. Small Vessel Stenting 7. Direct Stenting 8. Treatment of Chronic Total Coronary Occlusions 9. In-stent Restenosis 10. Restenosis, a Pragmatic Approach 11. Percutaneous Intervention in Acute Coronary Syndromes 12. Pediatrics Coronary Artery Abnormalities and Interventions 13. Post-angioplasty Dissection 14. Alternative Imaging 15. Calcified and Fibrotic Lesions 16. Ablative Techniques 17. Direct Myocardial Revascularization: Surgical and Catheter-based Approaches 18. Stent Retrieval 19. Adjunctive Therapies in Percutaneous Coronary Interventions 20. Local Drug Delivery using Drug-eluting Stents 21. The Significance of Biochemical Markers for Myocardial Damage in Interventional Procedures
No abstract is provided for this article.
No abstract is provided for this article.
Enhanced parasympathetic mechanisms may contribute to airway hyperresponsiveness. The present study examined whether the in vivo increase in airway responsiveness seen 18–24 h after either a single or chronic aerosolized allergen challenge protocol in actively sensitized Brown-Norway rats was due to altered parasympathetic mechanisms. The roles of central and reflex vagal mechanisms were studied by performing bilateral cervical vagotomy before measurement of airway responsiveness. Bilateral vagotomy failed to reduce the increase in airway responsiveness after either a single or chronic allergen challenge. The roles of increased neural release of acetylcholine (ACh) and increased end organ responsiveness were studied in vitro. The isometric responses of tracheal and bronchial strips to both electrical field stimulation and exogenously applied ACh from rats exposed both to single and chronic allergen challenges were compared with those from saline-exposed rats. The responses to electrical field stimulation and to exogenous ACh were not significantly enhanced 18–24 h after either protocol. We conclude that the airway hyperresponsiveness observed in this allergic rat model is not mediated through an enhancement of parasympathetic mechanisms.
Objectives We assessed the impact of vessel size on outcomes of stenting with biolimus-eluting degradable polymer stent (BES) and sirolimus-eluting permanent polymer stent (SES) within a randomized multicenter trial (LEADERS). Background Stenting of small vessels might be associated with higher rates of adverse events. Methods “All-comer” patients (n = 1,707) were randomized to BES and SES. Post-hoc–stratified analysis of angiographic and clinical outcomes at 9 months and 1 year, respectively, was performed for vessels with reference diameter ≤2.75 mm versus >2.75 mm. Results Of 1,707 patients, 429 patients in the BES group with 576 lesions and 434 patients in the SES group with 557 lesions had only small vessels treated (50.6% of the patient cohort). In patients with small vessels there was no significant difference in overall major adverse cardiac events (MACE) rate (12.1% vs. 11.8%; p = 0.89) or target lesion revascularization (TLR) rate (9.6% vs. 7.4%; p = 0.26) between BES and SES. The MACE and TLR rates in the small-vessel patient population were higher than in the large-vessel population. The TLR rate was 9.6% versus 2.6%, and MACE rate was 12.1% versus 7.1% for small versus large vessels in the BES arm (TLR: hazard ratio [HR] = 3.724, p = 0.0013; MACE: HR = 1.720, p = 0.0412). In the SES arm, TLR was 7.4% versus 5.1%, and MACE was 11.8% versus 10.3% in small versus large vessels (TLR: HR = 1.435, p = 0.2594; MACE: HR = 1.149, p = 0.5546). Conclusions Prevalence of small vessel disease is high in an “all-comer” population with higher TLR and MACE rates. The BES and SES seem equivalent in treatment outcomes of small vessels in this “all-comer” patient population.
