116 research outputs found
Diagnosis and management of left valvular heart disease with advanced echocardiography and cardiac computed tomography
This thesis explored the diagnosis, management and prognosis of the most common valvular heart diseases: aortic stenosis (AS) and mitral regurgitation (MR) and enlightened their challenging types: the discordant low-gradient severe AS and the secondary MR in non-ischemic cardiomyopathy. This thesis provides new insights into the use of fusion aortic valve area index, by incorporating the measurement of left ventricular outflow tract area on cardiac computed tomography in the continuity equation, for the diagnosis of low-gradient AS. For the treatment of low-gradient AS, TAVR is shown to result in reverse LV remodeling and functional recovery. In comparison to other minimal invasive surgical methods it results in less prosthesis-patient-mismatch although paravalvular aortic regurgitation is a caveat. Regarding the diagnostic assessment of secondary MR due to LV dysfunction this thesis concluded that LV GLS reflects the real LV dysfunction while LVEF overestimates LV function without accounting for the forward LV flow. Mitral valve repair offers LV reverse remodeling and increase in forward flow when used for the treatment of this challenging condition. Regarding the prognostication of low-gradient AS and secondary MR this thesis advocates for the evaluation of the valvular calcium on cardiac computed tomography and the evaluation of LV GLS and forward flow that are associated with survival.LUMC / Geneeskund
Il Nordest prima del Nordest
L'articolo introduce un volume monografico dedicato a casi di conflitto sociale (scioperi, occupazioni, vertenze sindacali, ma anche trasformazioni più lente) nel Veneto degli anni settanta, illustrando l'evoluzione del dibattito sul "decentramento produttivo" e sui distretti industriali e come questa prospettiva teorica abbia finito per negare il ruolo determinante svolto dai conflitti sociali (non sempre di classe e non sempre di fabbrica) nel consentire una evoluzione socialmente sostenibile di un modello produttivo inizialmente caratterizzato dal semplice abbassamento dei costi consentito dalla minore regolamentazione ambientale e sociale della piccola impresa e dell'artigianato
A laser-plasma accelerator driven by two-color relativistic femtosecond laser pulses
A typical laser-plasma accelerator (LPA) is driven by a single, ultrarelativistic laser pulse from terawatt- or petawatt-class lasers. Recently, there has been some theoretical work on the use of copropagating two-color laser pulses (CTLP) for LPA research. Here, we demonstrate the first LPA driven by CTLP where we observed substantial electron energy enhancements. Those results have been further confirmed in a practical application, where the electrons are used in a bremsstrahlung-based positron generation configuration, which led to a considerable boost in the positron energy as well. Numerical simulations suggest that the trailing second harmonic relativistic laser pulse is capable of sustaining the acceleration structure for much longer distances after the preceding fundamental pulse is depleted in the plasma. Therefore, our work confirms the merits of driving LPAs by two-color pulses and paves the way toward a downsizing of LPAs, making their potential applications in science and technology extremely attractive and affordable
A laser-plasma accelerator driven by two-color relativistic femtosecond laser pulses
A typical laser-plasma accelerator (LPA) is driven by a single, ultrarelativistic laser pulse from terawatt- or petawatt-class lasers. Recently, there has been some theoretical work on the use of copropagating two-color laser pulses (CTLP) for LPA research. Here, we demonstrate the first LPA driven by CTLP where we observed substantial electron energy enhancements. Those results have been further confirmed in a practical application, where the electrons are used in a bremsstrahlung-based positron generation configuration, which led to a considerable boost in the positron energy as well. Numerical simulations suggest that the trailing second harmonic relativistic laser pulse is capable of sustaining the acceleration structure for much longer distances after the preceding fundamental pulse is depleted in the plasma. Therefore, our work confirms the merits of driving LPAs by two-color pulses and paves the way toward a downsizing of LPAs, making their potential applications in science and technology extremely attractive and affordable
Outcome of cardiac surgery in patients with low preoperative ejection fraction
Background: In patients undergoing cardiac surgery, a reduced preoperative left ventricular ejection fraction (LVEF) is common and is associated with a worse outcome. Available outcome data for these patients address specific surgical procedures, mainly coronary artery bypass graft (CABG). Aim of our study was to investigate perioperative outcome of surgery on patients with low pre-operative LVEF undergoing a broad range of cardiac surgical procedures. Methods: Data from patients with pre-operative LVEF ≤40 % undergoing cardiac surgery at a university hospital were reviewed and analyzed. A subgroup analysis on patients with pre-operative LVEF ≤30 % was also performed. Results: A total of 7313 patients underwent cardiac surgery during the study period. Out of these, 781 patients (11 %) had a pre-operative LVEF ≤40 % and were included in the analysis. Mean pre-operative LVEF was 33.9 ± 6.1 % and in 290 patients (37 %) LVEF was ≤30 %. The most frequently performed operation was CABG (31 % of procedures), followed by mitral valve surgery (22 %) and aortic valve surgery (19 %). Overall perioperative mortality was 5.6 %. Mitral valve surgery was more frequent among patients who did not survive, while survivors underwent more frequently CABG. Post-operative myocardial infarction occurred in 19 (2.4 %) of patients, low cardiac output syndrome in 271 (35 %). Acute kidney injury occurred in 195 (25 %) of patients. Duration of mechanical ventilation was 18 (12-48) hours. Incidence of complications was higher in patients with LVEF ≤30 %. Stepwise multivariate analysis identified chronic obstructive pulmonary disease, pre-operative insertion of intra-aortic balloon pump, and pre-operative need for inotropes as independent predictors of mortality among patients with LVEF ≤40 %. Conclusions: We confirmed that patients with low pre-operative LVEF undergoing cardiac surgery are at higher risk of post-operative complications. Cardiac surgery can be performed with acceptable mortality rates; however, mitral valve surgery, was found to be associated with higher mortality rates in this population. Accurate selection of patients, risk/benefit evaluation, and planning of surgical and anesthesiological management are mandatory to improve outcome
Left ventricular systolic function assessment in secondary mitral regurgitation: left ventricular ejection fraction vs. speckle tracking global longitudinal strain
Cardiolog
Design and modelling of a novel damage-free steel column base
Column bases are fundamental components of a steel frame. However their design has not yet received appropriate attention. Conventional steel column bases cannot be easily repaired if damaged and exhibit difficult-to-predict and simulate stiffness, strength and hysteretic behaviour. This paper proposes a novel demountable and fully repairable column base for resilient steel buildings. The new column base isolates damage in easy-to-replace structural elements with the goal of minimizing repair time and disruption of the building service in the aftermath of a strong earthquake. Moreover, it can be easily constructed and deconstructed to enable sustainable steel frame designs. It provides significant flexibility in the design, with rotational stiffness and moment resistance that can be independently tuned. It has self-centering capability for reducing residual drifts. The paper presents design rules, an analytical hysteretic model and a 3D finite element model for the new column base
Three-dimensional transoesophageal echocardiographic visualization of malignant anomalous left main coronary origin and course causing sudden cardiac death
Cardiolog
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