22,200 research outputs found

    Comparative early outcomes of tricuspid Valve repair versus replacement for secondary tricuspid regurgitation

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    Background Comparative outcome data on tricuspid valve repair (TVr) versus tricuspid valve replacement (TVR) for severe secondary tricuspid regurgitation (TR) are limited. Methods We used a national inpatient sample to assess in-hospital morbidity and mortality, length of stay and cost in patients with severe secondary TR undergoing isolated TVr versus TVR. Results A total of 1364 patients (national estimate=6757) underwent isolated tricuspid valve surgery during the study period, of whom 569 (41.7%) had TVr and 795 (58.3%) had TVR. There was no difference in the prevalence of major morbidities between the two groups, except for liver disease and hepatic cirrhosis, which were more common in the TVR group. Before propensity matching, in-hospital mortality was similar between patients who underwent isolated TVr and TVR (8.1% vs 10.8%, p=0.093), but the incidence of postoperative morbidities differed: TVR was associated with higher rates of permanent pacemaker implantation and blood transfusion, while TVr was associated with more acute kidney injury. After rigorous propensity score matching, TVR was associated with significantly higher rates of in- hospital death (12% vs 6.9%, p=0.009) and permanent pacemaker implantation (33.7% vs 11.2%, p\u3c0.001). Postoperative morbidities and length of stay, however, were not different between the two groups. Nonetheless, cost of hospitalisation was 16% higher in the TVr group. Conclusions In patients undergoing isolated surgery for secondary TR, TVR is associated with higher in-hospital mortality and need for permanent pacemaker compared with TVr. Further studies are needed to understand the impact of the type of surgery on the short-term and long- term mortality in this complex undertreated populatio

    Hepatitis C viral evolution in genotype 1 treatment-naïve and treatment-experienced patients receiving telaprevir-based therapy in clinical trials

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    Background: In patients with genotype 1 chronic hepatitis C infection, telaprevir (TVR) in combination with peginterferon and ribavirin (PR) significantly increased sustained virologic response (SVR) rates compared with PR alone. However, genotypic changes could be observed in TVR-treated patients who did not achieve an SVR. Methods: Population sequence analysis of the NS3•4A region was performed in patients who did not achieve SVR with TVR-based treatment. Results: Resistant variants were observed after treatment with a telaprevir-based regimen in 12% of treatment-naïve patients (ADVANCE; T12PR arm), 6% of prior relapsers, 24% of prior partial responders, and 51% of prior null responder patients (REALIZE, T12PR48 arms). NS3 protease variants V36M, R155K, and V36M+R155K emerged frequently in patients with genotype 1a and V36A, T54A, and A156S/T in patients with genotype 1b. Lower-level resistance to telaprevir was conferred by V36A/M, T54A/S, R155K/T, and A156S variants; and higher-level resistance to telaprevir was conferred by A156T and V36M+R155K variants. Virologic failure during telaprevir treatment was more common in patients with genotype 1a and in prior PR nonresponder patients and was associated with higher-level telaprevir-resistant variants. Relapse was usually associated with wild-type or lower-level resistant variants. After treatment, viral populations were wild-type with a median time of 10 months for genotype 1a and 3 weeks for genotype 1b patients. Conclusions: A consistent, subtype-dependent resistance profile was observed in patients who did not achieve an SVR with telaprevir-based treatment. The primary role of TVR is to inhibit wild-type virus and variants with lower-levels of resistance to telaprevir. The complementary role of PR is to clear any remaining telaprevir-resistant variants, especially higher-level telaprevir-resistant variants. Resistant variants are detectable in most patients who fail to achieve SVR, but their levels decline over time after treatment


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    Background: Benefits of drug-eluting stents (DES) in percutaneous coronary intervention (PCI) are greatest in those at the highest risk of target vessel revascularization (TVR). While DES reduce restenosis, they cost more than bare metal stents (BMS), and necessitate prolonged dual antiplatelet therapy (DAPT) that increases costs, bleeding risk, and risk of complications if DAPT is prematurely discontinued. Our objectives were to assess if DES are preferentially used in those with higher predicted TVR risk, and to estimate whether lower use of DES (50% less DES use among patients with low predicted TVR risk) would be more cost-effective as compared with the existing pattern of DES use. Methods: We analyzed ~1.5 million PCI procedures in the NCDR CathPCI registry from Apr 2003 - Sept 2010. We estimated 1-year TVR risk assuming PCI with BMS using a previously validated prediction model. The main outcome measures were the rate of DES use and projected annual US societal costs at one year after PCI. We assessed the association between TVR risk with BMS DES use, and performed cost-effectiveness analysis of a lower use of DES (50% less DES use among patients with low predicted TVR risk) vs. existing DES use. Results: There was marked variation in physicians' use of DES (range = 2-100%). DES use was relatively high across all categories of predicted TVR risk (73.9% in patients with TVR risk 20%), with a modest correlation between predicted TVR risk and DES use (RR 1.005/1% increase in predicted TVR risk [95% CI = 1.005, 1.006]). Reducing DES use by 50% among the lowest risk patients was projected to lower US healthcare costs by $205 million/year while increasing the overall TVR event rate by 0.5% (95% CI= 0.49%, 0.51%) in absolute terms. Conclusions: DES use in the U.S. varies widely among physicians, with only modest correlation to patients' risk of restenosis. Less DES use among patients with low risk of restenosis has the potential for significant cost savings for the US healthcare system, while minimally increasing restenosis events

    Assist Is Just as Important as the Goal: Image Resurfacing to Aid Model's Robust Prediction

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    Adversarial patches threaten visual AI models in the real world. The number of patches in a patch attack is variable and determines the attack's potency in a specific environment. Most existing defenses assume a single patch in the scene, and the multiple patch scenarios are shown to overcome them. This paper presents a model-agnostic defense against patch attacks based on total variation for image resurfacing (TVR). The TVR is an image-cleansing method that processes images to remove probable adversarial regions. TVR can be utilized solely or augmented with a defended model, providing multi-level security for robust prediction. TVR nullifies the influence of patches in a single image scan with no prior assumption on the number of patches in the scene. We validate TVR on the ImageNet-Patch benchmark dataset and with real-world physical objects, demonstrating its ability to mitigate patch attack

    Experimental assessment of periodic piezoelectric composite arrays incorporating an anisotropic passive phase

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    This paper discusses the experimental assessment of a number of piezoelectric composite array structures incorporating a novel passive phase exhibiting anisotropic elastic properties. The passive polymer phase has been designed to limit inter-element crosstalk by attenuating lateral propagation across the array aperture. A selection of water coupled linear array coupons, operating with a nominal 400 kHz fundamental thickness mode frequency, has been prepared comprising the novel anisotropic passive phase. As a control, comparisons are made to similarly configured devices employing isotropic filler materials. Scanning laser vibrometry and measurements of electrical impedance characteristic on the array substrate demonstrate that the fundamental thickness mode of the devices configured with anisotropic polymer fillers is not contaminated by parasitic modes of vibration. The reasons for this are explained by considering the dispersion characteristics of the substrate. Water coupled hydrophone measurements of array element directivity; transmit voltage response and subsequently efficiency calculations illustrate that the observed reduction in mechanical cross talk has not been achieved at the expense of element sensitivity. Finally, comparisons between the experimental data and the PZFlex derived array responses are made, with good corroboration demonstrate

    A theoretical analysis of a piezoelectric ultrasound device with an active matching layer

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    This paper investigates the use of magnetically active materials in the matching layer of a piezoelectric transducer. This then allows the performance of the device to be dynamically altered by applying an external field. The effect that this new matching layer has on the performance of a typical device is theoretically investigated here. It transpires that the additional flexibility of an active matching layer can be used to maintain the efficiency of the device as the external load is varied

    Intertwining and supercuspidal types for p-adic classical groups

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    Let F be a non-archimedean local field of residual characteristic different from 2, and let G be a unitary, symplectic or orthogonal group, considered as the fixed point subgroup in = GL(N,F) of an involution s. We generalize the notion of a simple character for , which was introduced by Bushnell and Kutzko [Annals of Mathematics Studies 129 (Princeton University Press, 1993)], to define semisimple characters. Given a semisimple character ? for fixed by s, we transfer it to a character ?- for G and calculate its intertwining. If the torus associated to ?- is maximal compact, we obtain supercuspidal representations of G, which are new if the torus is split only over a wildly ramified extension