Pacing stress echocardiography

BACKGROUND: High-rate pacing is a valid stress test to be used in conjunction with echocardiography; it is independent of physical exercise and does not require drug administration. There are two main applications of pacing stress in the echo lab: the noninvasive detection of coronary artery disease through induction of a regional transient dysfunction; and the assessment of contractile reserve through peak systolic pressure/ end-systolic volume relationship at increasing heart rates to assess global left ventricular contractility. METHODS: The pathophysiologic rationale of pacing stress for noninvasive detection of coronary artery disease is obvious, with the stress determined by a controlled increase in heart rate, which is a major determinant of myocardial oxygen demand, and thereby tachycardia may exceed a fixed coronary flow reserve in the presence of hemodynamically significant coronary artery disease. The use of pacing stress echo to assess left ventricular contractile reserve is less established, but promising. Positive inotropic interventions are mirrored by smaller end-systolic volumes and higher end-systolic pressures. An increased heart rate progressively increases the force of ventricular contraction (Bowditch treppe or staircase phenomenon). To build the force-frequency relationship, the force is determined at different heart rate steps as the ratio of the systolic pressure (cuff sphygmomanometer)/end-systolic volume index (biplane Simpson rule). The heart rate is determined from ECG. CONCLUSION: Two-dimensional echocardiography during pacing is a useful tool in the detection of coronary artery disease. Because of its safety and ease of repeatability noninvasive pacing stress echo can be the first-line stress test in patients with permanent pacemaker. The force-frequency can be defined as up- sloping (normal) when the peak stress pacing systolic pressure/end-systolic volume index is higher than baseline and intermediate stress values, biphasic with an initial up- sloping followed by a later down-sloping trend, or flat or negative when peak stress pacing systolic pressure/end-systolic volume index is equal or lower than baseline stress values. This approach is certainly highly feasible and allows a conceptually immaculate definition of contractility with prognostic usefulness, but its therapeutic implications remains to be established. Bowditch treppe, assessed with pacing stress, can be used to assess the optimal stimulation frequency and to optimise the patient's chronotropic response in programming rate-adaptive pacemakers

iPSC-technology to model human cardiac diseases

the discovery that somatic cells can be reprogrammed to pluripotency as induced pluripotent stem cells(iPSC) has generated much interest since it presents an opportunity to generate patient- and disease- specific cell lines from which normal and diseased human cardiomyocytes (CMs

OPTIMISATION'S TECHNIQUES OF HULL SHAPES USING CFD RANSE SIMULATIONS WITH LOW NUMBER OF CELLS

2013/2014Negli ultimi anni le tecniche di idrodinamica numerica CFD hanno permesso di effettuare simulazioni al computer riguardanti l’ interazione tra solidi e fluidi. L’utilizzo dei software CFD permette una simulazione assolutamente realistica dei fenomeni idrodinamici, permettendo al progettista/programmatore di analizzare in tempi relativamente brevi molteplici soluzioni, onde sceglierne la migliore e di conseguenza molteplici macro o micro modifiche sulla carena prescelta, per valutarne l’impatto in termini di resistenza al moto, assetto, tenuta al mare, comfort. Negli ultimi anni si è visto un crescente utilizzo di algoritmi matematici di ottimizzazione multiobiettivo associati a modellatori 3d parametrici e successivamente a solutori CFD BEM a potenziale. Tali applicazioni tipicamente consentono di trovare le forme ottimali che, nel rispetto dei vincoli imposti, generino la minima resistenza d’onda ad una o più determinate velocità. Associare un processo di ottimizzazione ad un solutore viscoso RANS consente invece, conoscendo una moltitudine di parametri fisici in più, di ottimizzare seguendo più obiettivi ed in particolar modo la capacità di poter valutare l’effetto dell’attrito consente di poter ottimizzare le forme al fine di ridurre la resistenza totale all’avanzamento. Fino a ieri però un processo di ottimizzazione associato a simulazioni CFD RANS, se pur teoricamente possibile, era di fatto raramente utilizzato in quanto sconveniente a causa dell’enorme mole di calcoli da eseguire per valutare la bontà di centinaia di soluzioni diverse, rendendo troppo lungo ed oneroso il processo. Minimizzando il numero di celle computazionali riducendo così i tempi ei costi di simulazioni in ogni caso risultati adeguati, si dimostra come il modo simulazioni RANS viscosi saranno molto più utili rispetto a potenziali metodi BEM . Scopo infatti di questo lavoro è stato quello di associare un processo di ottimizzazione di carena basato sulla riduzione della RESISTENZA TOTALE ALL’AVANZAMENTO valutata attraverso l’utilizzo di simulazioni CFD RANSE eseguite con un dominio di calcolo a basso numero di celle. Tale dominio di calcolo deriva dall’accurato sviluppo di una procedura standardizzata che permette di eseguire simulazioni RANSE con una griglia standard che garantisce la bontà del risultato anche se “COARSE”. La presente trattazione oltre a fornire una panoramica sullo stato dell’arte in letteratura, presenta lo sviluppo di una metodologia atta ad eseguire simulazioni a basso numero di celle in maniera standardizzata, sviluppando tre tipi di meshatura standard, suddividendo le carene da studiare in tre differenti famiglie raggruppate per similitudine di geometrie e velocità di funzionamento e pertanto accomunate da una similare formazione ondosa : Round Bilge Displacement Hull, Round Bilge and Hard Chine Semiplaning Hull (Single and Multi-Hull), Hard Chine Planing Hull. Si è successivamente passati alla determinazione dei metodi di ottimizzazione investigando le potenzialità ed i limiti dei diversi metodi noti per eseguire ottimizzazioni multi-obiettivo, compreso il metodo „Sherpa“ basato su un robusto algoritmo combinato e progressivo finalizzato al raggiungimento della soluzione ottima riducendo automaticamente il numero di casi da simulare. Il processo di ottimizzazione in oggetto è stato applicato ad una innovativa carena semi-planante a spigolo dotata di bulbo prodiero a lama: si è partiti da una carena di base che soddisfaceva tutti i requisiti di progetto e, nel rispetto dei vincoli imposti, parametrizzata la carena ed impostati i set-up di calcolo, al termine dell’ottimizzazione si è ottenuta la geometria ottimale della stessa al fine della riduzione della resistenza totale a due differenti velocità (crociera e massima). Al termine delle attività si è proceduto con l’esecuzione di test in vasca navale su modello in scala per validare i risultati ottenuti per via numerica. La possibilità di ottenere simulazioni viscose con domini “standardizzati” a basso numero di celle permette l’analisi comparativa di molteplici soluzioni progettuali contenendo tempi e costi e con la certezza che i risultati siano realistici ed affidabili. L’innovativa standardizzazione studiata permette inoltre una riduzione del tempo di preparazione del set-up permettendo all’operatore di lanciare una simulazione su una nuova carena in pochi minuti, senza dover effettuare laboriose meshature ad-hoc e controlli di grid-independence dei risultati. L’utilizzo di queste griglie standard permette inoltre, come spiegato, di utilizzare le simulazioni CFD RANSE anche per eseguire ottimizzazioni multi-obiettivo riguardanti, per esempio, la riduzione della resistenza totale all’avanzamento. Senza griglie di questo tipo, raffinate ottimizzazioni basate su solutori viscosi sarebbero spesso antieconomiche. Difatti i risultati cui il presente lavoro è pervenuto riguardano un sensibile abbattimento dei tempi di calcolo necessari all’esecuzione di un’ottimizzazione morfologica di carena basata sulla minimizzazione della resistenza a due differenti velocità: in meno di 700 ore di calcolo con un tradizionale server a 12 core, ovvero in circa 80 ore utilizzando un centro di calcolo a 100 core, si riescono ad ottenere risultati importanti validi per fare delle valutazioni in senso assoluto sulla potenza necessaria all’imbarcazione per raggiungere le velocità prestabilite. Una procedura di questo tipo permette da una parte la possibilità di lavorare sulla resistenza totale o su altre quantità fisiche espresse dal solutore RANSE, dall’altra per la sua velocità e la sua semplicità d’utilizzo, consente l’avvicinamento alla CFD anche a progettisti di piccole imbarcazioni che fino ad oggi per problematiche di tempo e di budget non potevano approcciare ad una tecnologia così raffinata per progettare le loro carene. Difatti in un prossimo futuro l’utilizzo diffuso di tecniche di ottimizzazione o anche semplicemente di comparazione ed analisi di carene destinate ad imbarcazioni grandi e piccole, potrà contribuire in maniera significativa al risparmio di Potenza motrice installata a bordo (es. Grazie alla riduzione della resistenza totale), consentendo da una parte risparmi economici di carburante e dall’altra, soprattutto, una riduzione delle emissioni nocive in atmosfera.In recent years, the techniques of numerical hydrodynamic CFD allowed to perform computer simulations on the interaction between fluids and solids. The use of CFD software allows an absolutely realistic simulation of hydrodynamic phenomena, enabling the designer to analyze several solutions relatively quickly, in order to choose the best hull and therefore various macro or micro changes on the hull chosen, in order to evaluate its impact in terms of resistance, trim angle, seakeeping, comfort. In recent years we have seen an increasing use of mathematical algorithms for multi-objective optimisation related to 3D parametric modelers and then to potential CFD BEM solvers. Typically these applications allow you to find the optimal shape that, while respecting the constraints imposed, generate the minimum wave resistance to one or more certain speeds. The association of optimisation processes to a viscous RANSE solver enables to optimize following more targets, knowing a multitude of physical parameters in addition. In particular, the ability to assess the effect of friction on the hull’s shape, in order to reduce the total resistance. Until yesterday, however, an optimisation process associated with CFD RANSE simulations was in fact rarely used in the industrial sector, because it was considered quite inappropriate though theoretically possible. It was due to the large amount of calculations to be performed to evaluate the goodness of hundreds of different solutions, making the process too long and expensive. The present work demonstrates how viscous RANSE simulations methods can be easily used through number of computational cells minimization and the consequent reduction of time and costs of simulations. Indeed, the aim of this work has been to associate an hull optimisation process based on the reduction of total resistance, evaluated through the use of CFD RANSE simulations performed through computational domain with low number of cells. This calculation domain derives from the accurate development of a standardized procedure which allows to make RANSE simulations with a standard grid ensuring the accuracy of the result even if "COARSE". The present research, as well as providing an overview of the state of the art in literature, shows the development of an innovative methodology able to perform simulations with low number of cells in a standardized way, developing three types of standard meshing, dividing the hulls to be studied in three different families grouped by similarity of geometry and operation speed and having therefore in common a similar wave pattern: Round Bilge Displacement Hull, Round Bilge and Hard Chine Semiplaning Hull (Single and Multi-Hull), Hard Chine Planing Hull. The work subsequently involved the determination of the methods of optimisation investigating potentiality and limits of several already known methods to perform multi-objective optimisation, including the "Sherpa" one, based on a robust combined progressive algorithm aiming to achieve the optimal solution, automatically reducing the number of cases to be simulated. The optimization process has been applied to an innovative semi-planing hard-chine hull with blade bulbous bow: the process started from a basic hull matching all the project requirements and, respecting the imposed constraints, the hull has been parameterized and the calculation set-up has been established. At the end of the optimisation , the best hull geometry has been obtained in order to achieve the reduction of the total resistance at two different speeds (cruise and maximum). At the end of these activities, a towing tank tests on a scale model was carried out in order to validate the results numerically obtained. The chance to get viscous simulations with "standardized" domains with low number of cells allows comparative analysis of multiple design solutions by reducing time and cost, with the certainty that the results are realistic and reliable ones. The innovative process of standardization also makes a reduction in the time of preparation of the set-up allowing the operator to run a simulation on a new hull in a few minutes without having to make laborious ad-hoc meshing activities and grid-independence controls of results. The use of these standard grids also allows, as already said, the use of CFD RANSE simulations also to perform multi-objective optimizations relating to, for example, the reduction of the total resistance. Without such kind of grids, fine optimization based on viscous solvers would be often uneconomical. In fact, these work’s results concern a significant reduction in computation time necessary for the execution of a morphological hull optimization based on the resistance minimization at two different speeds. In less than 700 hours of calculation with a traditional 12 core server, or in about 80 hours using a to 100 cores computer-center, it is possible to achieve important results available to give some absolute assessments on the necessary power to the hull to reach the target speeds. A procedure like this, on one side, allows the opportunity to work on the total resistance or other physical quantities expressed by the RANSE solver, on the other side - thanks to its speed and its simplicity of use - enables the approach to the CFD also for small boats’ designers who, due to lack of time and budget, could not approach to a so refined hulls designing technology, up to now. In the near future the widespread use of optimization techniques, or even just comparative and analysis ones on hulls for large and small boats, will be able to significantly contribute to save engine power installed on board (i.e. by reducing the total resistance), allowing both economic fuel savings and, above all, a strong toxic emissions reduction in the atmosphere.XXVII Ciclo198

Carcinoid Heart Disease: A Rare Cause of Right Ventricular Dysfunction Evaluation by Transthoracic 2D, Doppler and 3-D Echocardiography

Carcinoid heart disease is a rare cause of heart failure with or without right valvular heart impairments. In this study, we showed a case of carcinoid tumour with hepatic metastases inducing carcinoid heart disease. Neuroendocrine heart involvement happens for severe tricuspid valve insufficiency and plaques on right ventricular (RV) walls produced by a release of serotonin (5-HT). A patient affected by primitive ileal tumour with 5-HT-secernent hepatic metastases inducing tricuspid insufficiency is showed. Transthoracic 2-D echocardiography showed tricuspid valve regurgitation and both right atrium, RV-walls plaques and RV dilation. Continue-wave Doppler showed a characteristic "dagger shaped" spectrum of tricuspid systolic flow. RV function was evaluated with 3-D transthoracic echocardiography. In particular, RV volumes, RV ejection fraction and stroke volume were defined by this technique. 2, 3-D echocardiography and Doppler method are useful techniques to show heart valves' derangements and RV function to non-invasively detect RV impairments in carcinoid heart disease

Small-scale convection in a plume-fed low-viscosity layer beneath a moving plate

Two-dimensional simulations using a thermomechanical model based on a finite-difference method on a staggered grid and a marker in cell method are performed to study the plume-lithosphere interaction beneath moving plates. The plate and the convective mantle are modelled as a homogeneous peridotite with a Newtonian temperature- and pressure-dependent viscosity. A constant velocity, ranging from 5 to 12.5 cm yr−1, is imposed at the top of the plate. Plumes are generated by imposing a thermal anomaly of 150 to 350 K on a 50 km wide domain at the base of the model (700 km depth); the plate atop this thermal anomaly is 40 Myr old. We analyse (1) the kinematics of the plume as it impacts the moving plate, (2) the dynamics of time-dependent small-scale convection (SSC) instabilities developing in the low-viscosity layer formed by spreading of hot plume material at the base of the lithosphere and (3) the resulting thermal rejuvenation of the lithosphere. The spreading of the plume material at the base of the lithosphere, characterized by the ratio between the maximum down- and upstream horizontal (dimensionless) velocities in the plume-fed sublithospheric layer, Peup/Pedown depends on the ratio between the maximum plume upwelling velocity and the plate velocity, Peplume/Peplate. For fast plate velocities and sluggish plumes (low Peplume/Peplate), plate motion drags most plume material and downstream flow is dominant. As Peplume/Peplate increases, an increasing part of the plume material flows upstream. SSC systematically develops in the plume-fed sublithospheric layer, downstream from the plume. Onset time of SSC decreases with the Rayleigh number. For vigorous plumes, it does not depend on plate velocity. For more sluggish plumes, however, variations in the plume spreading behaviour at the base of the lithosphere result in a decrease in the onset time of SSCs with increasing plate velocity. In any case, SSC results in uplift of the isotherm 1573 K by up to 20 km relative to its initial equilibrium depth at the impact poin

Demographic, Behavioral and Perceptual Comparisons of the U.S. Visitor Experience with Group Package Tours and Free Independent Travel to China

U.S. visitor demand for the China travel experience is anticipated to rise significantly through 2105, causing the Chinese government to employ 100 million service providers over the next six years and raising concern about service delivery and perceptions of the on-site China experience. In an effort to better understand these issues concerning U.S. visitors, this study investigated two specific types of U.S. travelers to China: Group Package Tour (GPT) visitors and Free Independent Travel (FIT) visitors. Results indicated that GPT visitors were more likely to be older and have higher household income than FIT visitors. Four trip-related characteristics of GPT and FIT visitors were found to be significantly different, with GPT visitors showing higher levels of satisfaction with the overall China on-site travel experience

Stress induced cardiomyopathy presenting as acute coronary syndrome: Tako-Tsubo in Mercogliano, Southern Italy

<p>Abstract</p> <p>Background</p> <p>Tako-tsubo syndrome (TTS) in its typical (apical) and atypical (non-apical) forms is being increasingly recognized in the West owing to early systematic coronary angiography in acute coronary syndromes (ACS).</p> <p>Aim of the study</p> <p>To assess the incidence, the clinical characteristics and the outcome of TTS in a single high volume cath lab in Southern Italy over the last 6 years.</p> <p>Methods</p> <p>Among 1674 consecutive patients (pts) referred to our coronary care units in the last 6 years (2001–2006) for ACS we selected 6 (0.5%) pts (6 women; age 57 ± 6 years) who fulfilled the following 4 criteria: 1) transient left ventricular wall motion abnormalities resulting in ballooning at contrast ventricolographic or echocardiographic evaluation; 2) normal coronary artery on coronary angiography performed 5 ± 9 hours from hospitalization; 3) new electrocardiographic ischemic-like abnormalities (either ST-segment elevation or T-wave inversion) and 4) emotional or physical trigger event.</p> <p>Results</p> <p>At admission all pts had presumptive diagnosis of ACS and ECG revealed ST elevation in 3 (50%) and T wave inversion with QT elongation in 3 (50%). In the acute phase cardiogenic shock occurred in 2 (33%) and heart failure in 1(16%). Presenting symptoms were chest pain in 6 (100%), dyspnoea in 2 (33%) and lipotimia in 1 (16%). At echocardiographic-ventricolographic assessment, the mechanical dysfunction (ballooning) was apical in all 6 pts ("classic" TTS). In all patients wall motion abnormalities completely reversed within 4.5 ± 1.5 days. The region of initial recovery was the anterior and lateral wall in 4 cases and the lateral wall in 2 cases. Ejection fraction was 35 ± 8% in the acute phase and increased progressively at discharge (55 ± 6%) and at 41 ± 20 months follow-up (60 ± 4%, p < 0.001 vs. baseline). All patients remained asymptomatic with minimal (aspirin, beta blockers, antihypertensive and antidislipidemic therapy) treatment.</p> <p>Conclusion</p> <p>Classic TTS is a frequent serendipitous diagnosis after coronary angiography showed "surprisingly" normal findings in a clinical setting mimicking an ACS. Despite its long-term good prognosis life threatening complications in the acute phase can occur.</p

Le dimensioni psicologiche nel monitoraggio del paziente diabetico in terapia con microinfusore: stato attuale e prospettive.

SUMMARY Psychological aspects in the evaluation of the diabetic patient treated with infusion pump-therapy: current state and perspectives This article aim is to offer a close examination of up-to-date theoretical contributions referring to the following subject: psychological aspects in CSII therapy. This close examination was made considering two different researches: the first by regarding the evaluation of the post implant period, and the second concerning the study of drop out causes. It was possible to find out problems and psychosocial changes caused by the implant, but also to specify critical points, useful to build necessary protocols, to support diabetological valuations and to suggest psychoeducational interventions

"Black Ink" Sonographic Pattern as a Predictor for Invasive Papillary Thyroid Micro Carcinoma: A Case Report

Background: This study investigated the utility of the Sonographic pattern "Black Ink" with BRAF mutation testing of thyroid fine-needle aspiration cytology specimens for the risk papillary thyroid microcarcinoma (PTMC). Case Presentation: We describe a case of a 41-year-old Caucasian woman affected by a ultrasonography "Black Ink" papillary thyroid microcarcinoma (PTMC) of the left lobe of the thyroid gland with very tiny size (Ø 0.4 cm). The characteristics, with the Diagnostic Imaging using Ultrasonography (US), Superb Micro-Vascular Imaging (SMI), fine-needle-aspiration cytology (FNAC) and mutation analysis are here discussed. There are more rare subtypes of thyroid cancer as papillary microcarcinoma "Black Ink" that even if small, are invasive and there is why the need to early diagnosis to avoid their aggressive behavior is needed. Nowadays, focusing on the size, the cut-off for non-occult tiny tumors has dropped to 0.3 cm. This value is of great relevance. Conclusion: Ultrasonography, FNAC and BRAF molecular study have proven to be the most sensitive diagnostic combination for the early detection of thyroid cancer. Despite the size of this micro-lesion, the Black Ink ultrasonographic pattern associated with malignant cytology at FNAC represents an important biological risk factor and could still be a predictor of the PTMC and risk for neck lymph node metastases

Quality of life and treatment satisfaction in adults with Type 1 diabetes: A comparison between continuous subcutaneous insulin infusion and multiple daily injections

Aims: The aim of this case-control study was to compare quality of life (QoL) and treatment satisfaction in adults with Type 1 diabetes (T1DM) treated with either continuous subcutaneous insulin infusion (CSII) or multiple daily injections (MDI). Methods: Consecutive patients aged between 18 and 55 years, and attending diabetes clinics for a routine visit, completed the Diabetes-Specific Quality-of-Life Scale (DSQOLS), the Diabetes Treatment Satisfaction Questionnaire (DTSQ) and the SF-36 Health Survey (SF-36). Case (CSII) and control subjects (MDI) were recruited in a 1 : 2 ratio. Results: Overall, 1341 individuals were enrolled by 62 diabetes clinics; 481 were cases and 860 control subjects. Cases had a longer diabetes duration and were more likely to have eye and renal complications. Age, school education, occupation and HbA1c were similar. Of control subjects, 90% followed glargine-based MDI regimens and 10% used NPH-based MDI regimens. On multivariate analysis, after adjusting for socioeconomic and clinical characteristics, scores in the following areas of the DSQOLS were higher in cases than control subjects: diet restrictions (β = 5.96; P &lt; 0.0001), daily hassles (β = 3.57; P = 0.01) and fears about hypoglycaemia (β = 3.88; P = 0.006). Treatment with CSII was also associated with a markedly higher DTSQ score (β = 4.13; P &lt; 0.0001) compared with MDI. Results were similar when CSII was compared separately with glargine- or NPH-based MDI regimens. Conclusions: This large, non-randomized, case-control study suggests quality of life gains deriving from greater lifestyle flexibility, less fear of hypoglycaemia, and higher treatment satisfaction, when CSII is compared with either glargine-based or NPH-based MDI regimens. © 2008 The Authors