Study of the nonlinear behavior of large bridge supports under earthquake solicitations

For very large bridges it is important to efficiently manage displacements and deformation during earthquakes and under the passage of vehicles to avoid damage and collapse of the structure. Classic solutions consist in implementing spring type shock absorbers, which convert the kinetic energy into heat energy, helping in dissipating it. A very effective and rather simple solution which is often adopted for large bridges and other sensitive structures is to implement pendular bearings, characterized by a curved geometry: they have the dual role of vertical support and of horizontal elastic support, the stiffness of which is proportional to the vertical reaction divided by the radius of curvature (called “pendulum effect of the support”). Between the moving parts of the support device, the sliding surfaces may have some roughness: in this case, the frictional force must be defeated before any displacement can take place. Whenever a force which would cause the structure to undergo a horizontal movement is applied: • the deck is horizontally stationary if the horizontal force is smaller than the frictional force; • the deck moves if the horizontal force is greater than the frictional force; • if there is movement, the deck will undergo both horizontal and vertical displacement. The behaviour is therefore, by definition, nonlinear. During the study of the Third Bosphorus Bridge in Turkey all phenomena were considered for the passage of a train; for the earthquake, on the other hand, only the pendulum effect was taken into account, while friction has been neglected. The present Master Thesis consists of studying and modelling the entire behavior, with both pendulum effect and friction, under earthquake solicitations, analyzing a real case, specifically the Third Bosphorus Bridge, and evaluating the dynamic response in time

Correlation of Left Ventricular Myocardial Work Indices with Invasive Measurement of Stroke Work in Patients with Advanced Heart Failure

ObjectivesThis study aimed to explore the correlation between left ventricular (LV) myocardial work (MW) indices and invasively-derived LV stroke work index (SWI) in a cohort of patients with advanced heart failure (AHF) considered for heart transplantation. BackgroundLeft ventricular MW has emerged as a promising tool for diagnostic and prognostic purposes in heart failure (HF) but its relationship with hemodynamic data derived from right heart catheterization (RHC) has not been assessed in patients with advanced heart failure yet. Materials and methodsConsecutive patients with AHF considered for heart transplantation from 2016 to 2021 performing RHC and echocardiography as part of the workup were included. Conventional LV functional parameters and LV MW indices, including LV global work index (GWI), LV global constructive work (GCW), LV global wasted work (GWW), LV global work efficiency (GWE), and other were calculated and compared with invasively-measured LV SWI. ResultsThe population included 44 patients. Median time between RHC and echocardiography was 0 days (IQR: 0-24). Median age was 60 years (IQR: 54-63). For the most part, etiology of HF was non-ischemic (61.4%) and all patients were either on class NYHA II (61.4%) or III (27.3%). Median left ventricular ejection fraction was 25% (IQR: 22.3-32.3), median NT-proBNP 1,377 pg/ml (IQR: 646-2570). LV global longitudinal strain (GLS) significantly correlated with LV SWI (r = -0.337; p = 0.031), whereas, LV ejection fraction (EF) did not (r = 0.308; p = 0.050). With regard to LV MW indices, some of them demonstrated correlation with LV SWI, particularly LV GWI (r = 0.425; p = 0.006), LV GCW (r = 0.506; p = 0.001), LV global positive work (LV GPW; r = 0.464; p = 0.003) and LV global systolic constructive work (GSCW; r = 0.471; p = 0.002). ConclusionAmong LV MW indices, LV GCW correlated better with invasively-derived SWI, potentially representing a powerful tool for a more comprehensive evaluation of myocardial function

Severe Impairment of Left Ventricular Regional Strain in STEMI Patients Is Associated with Post-Infarct Remodeling

Measures of global left ventricular (LV) systolic function have limitations for the prediction of post-infarct LV remodeling (LVR). Therefore, we tested the association between a new measure of regional LV systolic function-the percentage of severely altered strain (%SAS)- and LVR after acute ST-elevation myocardial infarction (STEMI). As a secondary objective, we also evaluated the association between %SAS and clinical events during follow-up

Right Atrial Pressure Is Associated with Outcomes in Patients with Heart Failure and Indeterminate Left Ventricular Filling Pressure

In a significant proportion of patients with left-sided heart failure (HF), left ventricular filling pressure (LVFP) may not be estimated using echocardiography, so filling pressure status may remain indeterminate. In these patients, mean right atrial pressure (mRAP) has been suggested as a surrogate of LVFP. The aim of this study was to determine whether high mRAP has prognostic value in patients with HF with indeterminate pressure (IP) and whether mRAP-based reclassification of patients with IP has an impact on outcomes

[Role of cardiac imaging in the diagnosis of infective endocarditis]

Infective endocarditis is an increasingly common disease in the hospital setting. Although the 2015 guidelines of the European Society of Cardiology deal extensively with many aspects of infective endocarditis, there are still unsolved problems related to diagnosis, in particular to the appropriate use of cardiac imaging methods, that require further study. The aim of this review is to analyze the advantages and limitations of the echocardiographic, radiological and nuclear imaging methods in order to identify diagnostic pathways applicable in clinical practice

Paradoxical low-flow phenotype in hospitalized heart failure with preserved ejection fraction

Low flow (LF) in heart failure with preserved ejection fraction (HFpEF) is a paradox but is associated with worse prognosis. Determinants of LF in HFpEF have not been clarified but their assessment could corroborate recognition and definition of such a paradoxical condition

[Non-ischemic ventricular dysfunction in COVID-19 patients: characteristics and implications for cardiac imaging on the basis of current evidence]

Coronavirus 2019 disease (COVID-19), caused by SARS-CoV-2, can lead to cardiac impairment with various types of clinical manifestations, including heart failure and cardiogenic shock. A possible expression of cardiac impairment is non-ischemic ventricular dysfunction, which can be related to different pathological conditions, such as myocarditis, stress and cytokine-related ventricular dysfunction. The diagnosis of these pathological conditions can be challenging during COVID-19; furthermore, their prevalence and prognostic significance have not been elucidated yet. The purpose of this review is to take stock of the various aspects of non-ischemic ventricular dysfunction that may occur during COVID-19 and of the diagnostic implications related to the use of cardiac imaging techniques

Incidence and mortality of infective endocarditis in the last decade: a single center study

Background Infective endocarditis (IE) is a significant disease characterized by high mortality and complications. The aim of this study was to evaluate the incidence/100 000 inhabitants and the in-hospital mortality/100 000 inhabitants of IE during the last 10 years in the province of Ravenna. Methods and results We reviewed the public hospitals discharge database from January 2010 to December 2020 using the international classification of disease codification (ICD-9) for IE. We used the Italian national statistical institute (ISTAT) archive to estimate the number of Ravenna inhabitants/year. In 10 years, we identified a total of 407 patients with diagnosis of IE. The incidence of IE increased significantly from 6.29 cases/ 100 000 inhabitants in 2010 to 19.58 cases/100 000 inhabitants in 2020 (P < 0.001). Also, the in-hospital mortality from IE increased over the same number of years, from 1.8 deaths/100 000 inhabitants in 2010 to 4.4 deaths/ 100 000 inhabitants in 2020 (P < 0.001). The mortality rate (%) of IE over the years did not increase (P = 0.565). Also, over the years there was no difference in the site of infection (P = 0.372), irrespective of the valve localization or type, native valve (P = 0.347) or prosthetic valve (P = 0.145). On logistic regression analysis, age was the only predictor of in-hospital mortality (odds ratio 1.045, 95% confidence interval: 1.015; 1.075, P = 0.003) Conclusions Ravenna-based data on IE showed increased disease incidence but unchanged mortality rate over 10 years of follow-up. Age remains the sole predictor of population-based mortality, irrespective of the nature of the valve, native or substitute, and the organism detected on microbiology. © 2022 Italian Federation of Cardiology - I.F.C. All rights reserved