Engineering Secure Adaptable Web Services Compositions

Service-oriented architecture defines a paradigm for building applications by assembling autonomous components such as web services to create web service compositions. Web services are executed in complex contexts where unforeseen events may compromise the security of the web services composition. If such compositions perform critical functions, prompt action may be required as new security threats may arise at runtime. Manual interventions may not be ideal or feasible. To automatically decide on valid security changes to make at runtime, the composition needs to make use of current security context information. Such security changes are referred to as dynamic adaptation. This research proposes a framework to develop web services compositions that can dynamically adapt to maintain the same level of security when unforeseen security events occur at runtime. The framework is supported by mechanisms that map revised security requirements arising at runtime to a new security configuration plan that is used to adapt the web services composition

Predictors and long-term impact of de novo aortic regurgitation in continuous flow left ventricular assist devices using vena contracta

The aim of this study was to identify the optimal echocardiographic measurement of aortic regurgitation (AR) in continuous flow left ventricular assist devices (LVAD) and determine risk factors and clinical implications of de novo AR. Echocardiographic images from consecutive patients who underwent LVAD implantation from February 2007 to March 2017 were reviewed. Severity of de novo AR was determined by vena contracta (VC). Preimplant clinical characteristics, LVAD settings at discharge, and outcomes including heart failure hospitalizations, all-cause mortality, and ventricular arrhythmias of patients with greater than or equal to moderate de novo AR were compared with those with mild or no AR. Among 219 patients, greater than or equal to moderate de novo AR occurred in 65 (29.7%). Left ventricular assist devices support duration was longer with greater than or equal to moderate AR than no or mild AR. In multivariable analysis, preimplant trivial AR and persistent aortic valve (AV) closure were independently associated with de novo AR. By time-varying covariate analysis, survival and freedom from cardiovascular events in greater than or equal to moderate AR were significantly worse (hazard ratio [HR] = 3.947, p \u3c 0.001 and HR = 4.666, p \u3c 0.001). In conclusion, de novo greater than or equal to moderate AR measured by VC increases risk of adverse events. Longer LVAD support duration, preimplant trivial AR, and a closed AV are associated with occurrence of greater than or equal to moderate de novo AR

Post Procedural Peak Left Atrial Contraction Strain Predicts Recurrence of Arrhythmia after Catheter Ablation of Atrial Fibrillation

Abstract Background Left atrial (LA) function can be impaired by the atrial fibrillation (AF) ablation and might be associated with the risk of recurrence. We sought to determine whether the post-procedural changes in LA function impact the risk of recurrence following AF ablation. Methods We retrospectively reviewed patients who underwent AF ablation between 2009 and 2011 and underwent transthoracic echocardiography before ablation, 1-day and 3-month after ablation. Peak left atrial contraction strain (PACS) and left atrial emptying fraction (LAEF) were evaluated during sinus rhythm and compared across the three time points. The primary endpoint was atrial tachyarrhythmia recurrence after ablation. Results A total of 144 patients were enrolled (mean age 61 ± 11 years, 77% male, 46% persistent AF). PACS and LAEF initially decreased 1-day following ablation but partially recovered within 3 months in PAF patients, with a similar trend in the PerAF patients. After median 24 months follow-up, 68 (47%) patients had recurrence. Patients with recurrence had higher PACS1-day than that in non-recurrence subjects (-10.9 ± 5.0% vs. -13.4 ± 4.7%, p = 0.003). PACS1-day -12% distinguished recurrence cases with a sensitivity of 67.7% and specificity of 60.5%. The Kaplan–Meier curves showed significant difference in 5-year cumulative probability of recurrence between those with PACS ≥ -12% and PACS < -12% (log rank p < 0.0001). Multivariate regression showed that PACS1-day was an independent risk factor of arrhythmia recurrence. Conclusions Left atrial function deteriorates immediately following AF ablation and partially recovers in 3 months but remains abnormal in the majority of patients. PACS1-day post procedure predicts arrhythmia recurrence at long-term follow-up

Impact of atrial fibrillation on outcomes of aortic valve implantation

New or preexisting atrial fibrillation (AF) is frequent in patients undergoing aortic valve replacement. We evaluated whether the presence of AF during transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR) impacts the length of stay, healthcare adjusted costs, and inpatient mortality. The median length of stay in the patients with AF increased by 33.3% as compared with those without AF undergoing TAVI and SAVR (5 [3 to 8] days vs 3 [2 to 6] days, p \u3c0.0001 and 8 [6 to 12] days vs 6 [5 to 10] days, p \u3c0.0001, respectively). AF increased the median value of adjusted healthcare associated costs of both TAVI ($46,754 [36,613 to 59,442] vs$49,960 [38,932 to 64,201], p \u3c0.0001) and SAVR ($40,948 [31,762 to 55,854] vs$45,683 [35,154 to 63,026], p \u3c0.0001). The presence of AF did not independently increase the in-hospital mortality. In conclusion, in patients undergoing SAVR or TAVI, AF significantly increased the length of stay and adjusted healthcare adjusted costs but did not independently increase the in-hospital mortality