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This paper presents a computer-aided design (CAD) module able to analyze different manufacturing configurations of tubes used in mechanical assemblies, such as exhaust system manifolds. It can be included in the knowledge-based expert system category and has been implemented into a CAD platform as a dedicated module able to take into account manufacturing requirements related to tube bending, hydroforming, and cutting. The expert's knowledge, in terms of set of rules and criteria, has been implemented by means of the automation tools of CATIAV5R10 according to the so-called methodological formal approach. The resulting module is able to join different tubes starting from their geometrical models, obtaining a set of manufacturing alternatives. Each of them is verified with respect to collisions with a bending machine and also in terms of hydroforming process feasibility. Only those solutions that satisfy these checks are accepted as feasible and ranked according to three evaluation criteria related to manufacturing cost and easiness. The system is completely automatic and able to analyze more than 100 different configurations in Keywords: design to manufacturing, knowledge based expert system, tube bending, tube hydroforming, CAE

Abstract Background B-type natriuretic peptide (BNP) is increased in post-cardiac surgery patients, however the mechanisms underlying BNP release are still unclear. In the current study, we aimed to assess the relationship between postoperative BNP levels and left ventricular filling pressures in post-cardiac surgery patients. Methods We prospectively enrolled 134 consecutive patients referred to our Center 8 ± 5 days after cardiac surgery. BNP was sampled at hospital admission and related to the following echocardiographic parameters: left ventricular (LV) diastolic volume (DV), LV systolic volume (SV), LV ejection fraction (EF), LV mass, relative wall thickness (RWT), indexed left atrial volume (iLAV), mitral inflow E/A ratio, mitral E wave deceleration time (DT), ratio of the transmitral E wave to the Doppler tissue early mitral annulus velocity (E/E'). Results A total of 124 patients had both BNP and echocardiographic data. The BNP values were significantly elevated (mean 353 ± 356 pg/ml), with normal value in only 17 patients (13.7%). Mean LVEF was 59 ± 10% (LVEF ≥50% in 108 pts). There was no relationship between BNP and LVEF (p = 0.11), LVDV (p = 0.88), LVSV (p = 0.50), E/A (p = 0.77), DT (p = 0.33) or RWT (p = 0.50). In contrast, BNP was directly related to E/E' (p < 0.001), LV mass (p = 0.006) and iLAV (p = 0.026). At multivariable regression analysis, age and E/E' were the only independent predictors of BNP levels. Conclusion In post-cardiac surgery patients with overall preserved LV systolic function, the significant increase in BNP levels is related to E/E', an echocardiographic parameter of elevated LV filling pressures which indicates left atrial pressure as a major determinant in BNP release in this clinical setting.

Mitral valve prolapse (MVP) is still a clinical challenging problem. In this report, we review the main characteristics of this entity. Epidemiology of MVP, which relies on the diagnostic criteria adopted, and the incidence of complications, both arrhythmic and structural, are influenced by the characteristics of the population studied, which may lead to bias in data interpretation. Even the definition of MVP may differ according to the cardiologist's or cardiac surgeon's point of view. Usually, cardiologists define MVP as the protrusion of all or part of the mitral leaflets into the left atrium, independent of maintenance of coaptation. Therefore, using this definition, mitral regurgitation is considered as a complication rather than a diagnostic criterion. Arrhythmias, either supraventricular or ventricular, are other possible complications, mostly not life-threatening and associated with myxomatous degeneration of the valve. Diagnosis of MVP is based on echocardiography, which provides detailed anatomic and functional evaluation of the affected valve. Leaflet thickness and motion as well as presence and severity of mitral regurgitation can be assessed, with important diagnostic and prognostic implications. Echocardiographic evaluation of the mitral valve requires a systematic approach in order to define the leaflet/scallop involved and the mechanisms of mitral regurgitation. To this aim, three-dimensional reconstruction may add further insights into objective rendering of mitral valve pathology. Finally, surgical timing in mitral regurgitation due to MVP is an evolving issue and the likelihood of surgical repair is a crucial factor in the optimal timing of surgical intervention, especially in asymptomatic patients with severe mitral regurgitation.

The implementation of a digital echocardiography laboratory exists today using the DICOM (Digital Imaging Communication in Medicine) standard to acquire, store and transfer echocardiographic digital images. The components of a laboratory include: 1) digital echocardiography machines with DICOM output, 2) a switched high-speed local area network, 3) a DICOM server with abundant local storage, and 4) a software to manage image and measurement information. The aim of this article was to describe the critical components of a digital echocardiography laboratory, discuss strategies for implementation, and describe some of the pitfalls that we encountered in our own implementation of the digital third level echocardiography laboratory.