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Mulet, Parada Miguel. "Intensity independent feature extraction and tracking in echocardiographic sequences." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343557.
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Otsuki, Denise Aya. "Hemodiluição normovolêmica aguda: estudo experimental comparativo utilizando amido hidroxietílico a 6% ou solução de Ringer lactato." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-03022005-113414/.
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Hemodiluição normovolêmica aguda é um procedimento utilizado para diminuir a necessidade de transfusões sangüíneas em diversas cirurgias de grande porte. Poucos trabalhos avaliam as alterações hemodinâmicas e perfusão tecidual através de estudo ecocardiográfico e tonometria gástrica. Foram utilizados 23 porcos (peso 46.6 ± 6.0 kg) anestesiados com quetamina, fentanil e propofol e instrumentados para monitorização hemodinâmica convencional. Os animais foram randomizados em três grupos 30 minutos após estabilização da anestesia: Grupo I (Controle), Grupo II (amido hidroxietílico) e Grupo III (Ringer lactato). Os animais do grupo II e III foram submetidos ao protocolo de hemodiluição com hematócrito alvo de 15%. A retirada de sangue foi realizada em 30 minutos e a expansão plasmática feita simultaneamente com amido hidroxietílico ou Ringer lactato nas proporções de 1:1 ou 1:3 em relação ao sangue retirado. Os parâmetros hemodinâmicos e de oxigenação, pH gástrico, ecocardiografia transesofágica (fração de ejeção através do método Simpson) foram coletados antes da hemodiluição (T0), no fim do procedimento de hemodiluição (T1) e após uma e duas horas (T2, T3). Os dados foram submetidos a análise de variância para medidas repetidas, seguida pelo teste Tukey e teste T student. Resultados: Em relação aos parâmetros do grupo controle, não houve diferença significante durante todo o procedimento. No grupo II e grupo III, houve aumento no índice cardíaco após hemodiluição (T0=5,80±1,46; T1=10,64±1,69 L.min-1.m2 e T0=5,53±1,18, T1=7,91±1,40 L.min-1.m2 respectivamente), e diminuição do índice de resistência vascular sistêmica (T0=1753±336, T1=822±140 dina.s.cm-5.m-2 e T0=1673±566, T1=1026±190 dina.s.cm-5.m-2 respectivamente), ambos estatisticamente significante. A fração de ejeção apresentou aumento significativo após a hemodiluição no grupo II. O pH gástrico diminuiu significativamente no grupo III. O lactato arterial aumentou de forma significante no grupo III após a hemodiluição. A microscopia eletrônica do ventrículo esquerdo mostraram discreta destruição de miofilamentos no grupo II. Houve destruição importante nas miofibrilas no grupo III. Conclusão: Estes resultados sugerem que na hemodiluição moderada a grave, o amido hidroxietílico consegue preservar melhor a estabilidade hemodinâmica do que a solução de Ringer lactato.Normovolemic acute hemodilution is a procedure utilized to decrease the needs of blood transfusion during a variety of surgical procedures. Nevertheless, there are few works that evaluate its pulmonary effects as well as hemodynamic changes by means of echocardiography and tonometric evaluation. Methods: 23 anesthetized pigs (weight 46.6 ± 6.0 kg) were instrumented for standard hemodynamic monitoring. In order to prevent possible effects of inhaled anesthetics on pulmonary mechanics, intravenous anesthesia was chosen and consisted of ketamine, fentanyl and propofol administered throughout the study. Thirty minutes after anesthesia stabilization animals were randomized in three groups: Group I (Control), Group II (hydroxyethyl starch) and Group III (Lactated Ringers). Animals of group II and III were submitted to acute normovolemic hemodilution to reach a pre-established hematocrit around 15%. Blood withdrawal was accomplished in thirty minutes and plasma expansion was performed simultaneously with hydroxyethyl starch or Lactated Ringers administered in a proportion of 1:1 or 3:1 in relation to the amount of bloods withdrawn. Hemodynamic, gastric pH, transesophageal echography (ejection fraction, by Simpon method) and oxygen transport were measured before blood withdrawal (T0), at the end of hemodilution (T1), one and two hours after the end of hemodilution (T2, T3). Data were submitted to analysis of Variance for repeated measures followed by the Tukey test and also to a student T test. Results: In regard to all parameters of Group I (Control), there were no significant difference during the whole procedure. In Group II and Group III, there was an increase in cardiac index after hemodilution (T0=5.80±1.46; T1=10.64±1.69 L.min-1.m2 and T0=5.53±1.18, T1=7.91±1.40 L.min-1.m2), and a decrease in systemic vascular resistance index (T0=1753±336, T1=822±140 dyne.s.cm-5.m-2 and T0=1673±566, T1=1026±190 dyne.s.cm-5.m-2), both statistically significant. Ejection Fraction increased significantly after hemodilution in group II. Gastric pH decreased significantly in Group III, and arterial lactate increased significantly after hemodilution in group III. Electron microscopy of left ventricular bipsies showed a slight destruction in filament and preserved myofibrillar ultrastructure in group II. There was important destruction in myofibrillar ultrastructure in group III. Conclusion: These results suggest that in severe hemodilution, hydroxyethyl starch preserves hemonodynamic stability better than Lactate Ringers.
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Huez, Sandrine. "Contribution à l'étude de la circulation pulmonaire et de la fonction ventriculaire droite dans l'hypertension pulmonaire: apports de l'échocardiographie et de l'imagerie par Doppler tissulaire." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210379.
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Campos, Paulo César Gobert Damasceno [UNIFESP]. "Regurgitação valvar funcional em insuficiência cardíaca congestiva descompensada: monitoração não-invasiva por bioimpedância cardíaca e ecocardiografia e resposta à terapêutica." Universidade Federal de São Paulo (UNIFESP), 2009. http://repositorio.unifesp.br/handle/11600/10021.
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Publico-11760b.pdf: 1959621 bytes, checksum: 2665d88fb8fec237d73fdc84aa78a26a (MD5)Introdução: A insuficiência cardíaca congestiva (ICC) descompensada pode ser definida como a evidência de sinais e sintomas de insuficiência cardíaca (IC) ao repouso e representa estado de ativação neuro-hormonal intensa, secundária ao déficit de perfusão renal. Regurgitações valvares funcional mitral e tricúspide são causas reversíveis de diminuição de fluxo sanguíneo sistêmico eficaz. O impacto de tais regurgitações sobre o débito cardíaco, sobre o conteúdo de fluido torácico, sobre as dimensões de câmaras cardíacas e sobre a função do aparato valvular pode ser monitorado de forma não-invasiva, antes e após a otimização do tratamento clínico. Objetivo: Avaliar o papel das regurgitações valvares funcional mitral e tricúspide como causas reversíveis de redução do débito cardíaco em ICC descompensada, e que acompanham a disfunção ventricular sistólica em miocardiopatias isquêmica e não-isquêmica. Métodos: catorze pacientes do sexo masculino (66 ± 8 anos de idade), fração de ejeção (24 ± 5%) secundária às miocardiopatias isquêmica (71%) e não-isquêmica (29%), apresentaram ICC descompensada com evidência clínica de regurgitações valvares mitral e tricúspide, foram avaliados por Bioimpedância cardíaca e ecocardiografia antes e uma semana após otimização de tratamento clínico. Resultados: o tratamento farmacológico de ICC descompensada foi acompanhado de redução de peso corpóreo de 82,9 a 76 kg (P<0,01), elevação no índice cardíaco (de 2,1 para 2,6 L/min/m2; P<0,01), redução na pressão sistólica da artéria pulmonar (de 58 para 35 mm Hg; P<0,001), conteúdo de fluido torácico (de 39 para 32 kOhm; P<0,001) e resistência vascular sistêmica (de 1633 para 1209 dinas/seg/cm5; P<0.001). A melhora dessas regurgitações incluiu redução nas dimensões das câmaras atriais esquerda e direita (de 27 para 24 cm2 e de 26 para 23 cm2, respectivamente; (P<0,001), diminuição das regurgitações mitral e tricúspide detectadas pelo Doppler colorido (P < 0,01), do volume regurgitante mitral (de 105 para 65 ml; P<0,001), e do tamanho efetivo do orifício regurgitante mitral (de 0,8 para 0,6 cm2; P<0,01). Conclusões: Na ICC descompensada, as regurgitações funcionais mitral e tricúspide contribuem para redução do débito cardíaco, aumento do conteúdo fluido torácico e da resistência vascular sistêmica, simultaneamente ao aumento de câmaras atriais e do orifício valvar, os quais podem ser melhorados com tratamento clínico. A bioimpedância cardíaca e a ecocardiografia fornecem avaliação seriada não-invasiva de parâmetros hemodinâmicos e função valvar nestes pacientes.
Objective: We hypothesized that functional mitral and tricuspid valvular incompetence (MR and TR, respectively) are reversible causes of reduced cardiac output in decompensated heart failure (DF) that accompanies systolic dysfunction in ischemic or nonischemic cardiomyopathy. Background: DF, defined as signs and symptoms of heart failure at rest, is rooted in a salt-avid state transduced by neurohormonal activation secondary to impaired renal perfusion. Functional MR and TR are reversible causes of reduced systemic blood flow. Their impact on cardiac output, thoracic fluid content, cardiac chamber dimensions, and valvular apparatus function can be monitored noninvasively, before and after optimized medical management. Methods: Fourteen male subjects (66 ± 8 years old) with reduced ejection fraction (24 ± 5%) secondary to ischemic (71%) or nonischemic (29%) cardiomyopathy, who developed DF with clinical evidence of mitral (MR) and tricuspid (TR) valvular incompetence, were each assessed by bioimpedance and echocardiography before and 1 week after optimized medical management restored compensated failure. Results: Pharmacologic elimination of DF was accompanied by a reduction in body weight (p<0.01). Hemodynamic improvements included a rise in cardiac index (2.1 to 2.6 L/min/m2; p<0.01) and a reduction in predicted pulmonary artery systolic pressure (58 to 35 mm Hg; p<0.001), thoracic fluid content (39 to 32 kOhm; p<0.001), and systemic vascular resistance (1633 to 1209 dynes/sec/cm5; p<0.001). Improvements in functional MR and TR included reductions in left and right atrial areas (27 to 24 cm and 26 to 23 cm2, respectively; p<0.001), color-flow grading of MR and TR severity (p<0.01), mitral regurgitant volume (105 to 65 mL; p<0.001), and effective MR orifice size (0.8 to 0.6 cm2; p<0.01). Conclusions: In DF, functional MR and TR contribute to reduced cardiac output, increased thoracic fluid content, and systemic vascular resistance, together with enlarged atria and valvular orifice size, which can be improved by medical management. Bioimpedance and echocardiography provide for serial noninvasive assessments of hemodynamic status and valvular function in such cases.
TEDE
BV UNIFESP: Teses e dissertações
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Fayssoil, Abdallah. "Phénotypage cardiaque des dystrophies musculaires à l'aide des ultrasons." Thesis, Versailles-St Quentin en Yvelines, 2014. http://www.theses.fr/2014VERS0062/document.
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Les myopathies d’origine génétique sont des pathologies musculaires en rapport avec des anomalies génétiques. Les myopathies sont à l’origine d’un handicap physique majeur et affectent souvent la fonction respiratoire et parfois le cœur. Nous nous sommes intéressés à la caractérisation myocardique de 4 types de myopathies d’origine génétique à l’aide de l’échocardiographie Doppler : myopathie de Duchenne, sarcoglycanopathies, MELAS syndrome et maladie de Pompe.Nous avons analysé la fonction cardiaque dans 2 modèles murins de dystrophies musculaires: la souris mdx et la souris sgca null. En clinique, nous avons analysé la fonction cardiaque des sujets atteints de myopathie de Duchenne, de sarcoglycanopathies, de MELAS syndrome et de maladie de Pompe en échocardiographie Doppler.Dans les modèles animaux, nous avons retrouvé des anomalies myocardiques chez la souris mdx et chez la souris sgca null. Chez l’homme, l’atteinte myocardique est sévère chez les sujets atteints de myopathie de Duchenne et certains patients présentent un asynchronisme ventriculaire soulevant les indications éventuelles de resynchronisation myocardique. Les sujets atteints de gamma sarcoglycanopathies présentent de façon significative des anomalies de contraction du ventricule gauche comparativement aux sujets atteints d’alpha-sarcoglycanopathies. La fonction ventriculaire droite et gauche est préservée chez les sujets atteints de maladie de Pompe. Les sujets atteints de MELAS présentent des hypertrophies du ventricule gauche. L’analyse génétique retrouve une corrélation significative entre le taux d’hétéroplamie et la survenue d’événements cliniquesMuscular dystrophies are genetic neuromuscular disorders that affect skeletal muscle. We sought to assess heat involvement in four genetic muscular disorders : Duchenne muscular dystrophy, sarcoglycanopathies, MELAS and adulte Pompe disease. In animal models, we sought to assess, using Echocardiography Doppler, mdx mice and sgca null mice. Myocardiac abnormalities were found in mdx mice and sgca null mice. Clinical studies found severe cardiac impairment in Duchenne muscular dystrophies and ventricular asynchrony was found in patients with severe heart failure. Patients with gamma sarcoglycanopathy have significant alteration of left ventricular function in comparison with patients with alpha sarcoglycanopathy. Left and right ventricular function were preserved in patients with Pompe disease. Left ventricular hypertrophy was found in patients with MELAS. Genetic analysis disclosed significant correlation between heteroplasmy and significant clinical events
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Karagiannis, Stefanos E. "Clinical stress echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10524.
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Voormolen, Marco Marien. "Three dimensional harmonic echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10598.
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Krenning, Boudewijn Juriaan. "Quantitative Three-dimensional Echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10695.
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Williams, Quentin. "Contrast echocardiography perfusion imaging." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427650.
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Yao, Cheng. "3D echocardiography image compounding." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/3d-echocardiography-image-compounding(5e1b0ddd-6d47-4305-8de4-aa2260489131).html.
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Echocardiography (echo) is a widely available method to obtain images of the heart, however, echo can suffer due to the presence of artefacts, high noise and a restricted field-of-view. One method to overcome these limitations is to use multiple images, using the "best" parts from each image to produce a higher quality "compounded" image. This thesis describes a new method to allow multiple 3D echo images to be compounded into a single better quality volume. I have proposed a definition for an "ideal" compounded image and have used this to guide the design of my compounding method, in particular designing a method to reduce the effect of image artefacts and to make use of larger numbers of images. My compounding method has been validated using phantom, volunteer and clinical images. The overall motivations for improving echo image quality are twofold: Firstly to provide clinicians with higher quality images which I hope will improve the accuracy of clinical decision making. Secondly to provide higher quality images for subsequent post-processing algorithms. A number of methods have been proposed to compound sets of ultra-sound images, all of which have reported improvements in image quality. However, previous 3D compounding methods have typically been applied to a relatively small number of images (most of them only use two images, and only one uses six images). I have investigated the effect of compounding with larger numbers of images. Results showed continued improvement in image quality up to ten images (the maximum number we deemed feasible to acquire in a clinical setting and it is approximately double of images used previously). Artefacts occur regularly within echo images, particularly shadowing artefacts (due to the highly reflecting interfaces caused by the ribs and lungs when imaging the heart). However, previous 3D compounding methods haven’t directly claimed and demonstrated the effect of artefacts. Therefore, I have proposed a 3D compounding algorithm which specifically aims to reduce the effect of echo artefacts (shadowing) as well as improving the signal-to-noise ratio, contrast, and extending the field-of-view. My method to reduce the effect of artefacts is to weight image information from different views based on a local feature coherence/consistency. I hypothesize that the presence of an artefact in an image varies greatly depending on view direction, therefore much lower consistency values will be calculated for artefact regions enabling them to be detected, and their influence on the compounded image to be greatly reduced. The accuracy of the image registration is important and errors will likely affect the final compounded images quality. In addition to registration ac-curacy my system needs to work robustly and have a large enough capture range to enable automatic registration from a suitable starting position.
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Chykeyuk, Kiryl. "Analysis of 3D echocardiography." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:823cd243-5d48-4ecc-90e7-f56d49145be8.
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Heart disease is the major cause of death in the developed world. Due to its fast, portable, low-cost and harmless way of imaging the heart, echocardiography has become the most frequent tool for diagnosis of cardiac function in clinical routine. However, visual assessment of heart function from echocardiography is challenging, highly operatordependant and is subject to intra- and inter observer errors. Therefore, development of automated methods for echocardiography analysis is important towards accurate assessment of cardiac function. In this thesis we develop new ways to model echocardiography data using Bayesian machine learning methods and concern three problems: (i) wall motion analysis in 2D stress echocardiography, (ii) segmentation of the myocardium in 3D echocardiography, and (iii) standard views extraction from 3D echocardiography. Firstly, we propose and compare four discriminative methods for feature extraction and wall motion classification of 2D stress echocardiography (images of the heart taken at rest and after exercise or pharmalogical stress). The four methods are based on (i) Support Vector Machines, (ii) Relevance Vector Machines, (iii) Lasso algorithm and Regularised Least Squares, (iv) Elastic Net regularisation and Regularised Least Squares. Although all the methods are shown to have superior performance to the state-of-the-art, one conclusion is that good segmentation of the myocardium in echocardiography is key for accurate assessment of cardiac wall motion. We investigate the application of one of the most promising current machine learning techniques, called Decision Random Forests, to segment the myocardium from 3D echocardiograms. We demonstrate that more reliable and ultrasound specific descriptors are needed in order to achieve the best results. Specifically, we introduce two sets of new features to improve the segmentation results: (i) LoCo and GloCo features with a local and a global shape constraint on coupled endoand epicardial boundaries, and (ii) FA features, which use the Feature Asymmetry measure to highlight step-like edges in echocardiographic images. We also reinforce the traditional features such as Haar and Rectangular features by aligning 3D echocardiograms. For that we develop a new registration technique, which is based on aligning centre lines of the left ventricles. We show that with alignment performance is boosted by approximately 15%. Finally, a novel approach to detect planes in 3D images using regression voting is proposed. To the best of our knowledge we are the first to use a one-step regression approach for the task of plane detection in 3D images. We investigate the application to standard views extraction from 3D echocardiography to facilitate efficient clinical inspection of cardiac abnormalities and diseases. We further develop a new method, called the Class- Specific Regression Forest, where class label information is incorporating into the training phase to reinforce the learning from semantically relevant to the problem classes. During testing the votes from irrelevant classes are excluded from voting to maximise the confidence of output predictors. We demonstrate that the Class-Specific Regression Random Forest outperforms the classic Regression Random Forest and produces results comparable to the manual annotations.
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Dindoyal, I. "Foetal echocardiographic segmentation." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/20169/.
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Congenital heart disease affects just under one percentage of all live births [1]. Those defects that manifest themselves as changes to the cardiac chamber volumes are the motivation for the research presented in this thesis. Blood volume measurements in vivo require delineation of the cardiac chambers and manual tracing of foetal cardiac chambers is very time consuming and operator dependent. This thesis presents a multi region based level set snake deformable model applied in both 2D and 3D which can automatically adapt to some extent towards ultrasound noise such as attenuation, speckle and partial occlusion artefacts. The algorithm presented is named Mumford Shah Sarti Collision Detection (MSSCD). The level set methods presented in this thesis have an optional shape prior term for constraining the segmentation by a template registered to the image in the presence of shadowing and heavy noise. When applied to real data in the absence of the template the MSSCD algorithm is initialised from seed primitives placed at the centre of each cardiac chamber. The voxel statistics inside the chamber is determined before evolution. The MSSCD stops at open boundaries between two chambers as the two approaching level set fronts meet. This has significance when determining volumes for all cardiac compartments since cardiac indices assume that each chamber is treated in isolation. Comparison of the segmentation results from the implemented snakes including a previous level set method in the foetal cardiac literature show that in both 2D and 3D on both real and synthetic data, the MSSCD formulation is better suited to these types of data. All the algorithms tested in this thesis are within 2mm error to manually traced segmentation of the foetal cardiac datasets. This corresponds to less than 10% of the length of a foetal heart. In addition to comparison with manual tracings all the amorphous deformable model segmentations in this thesis are validated using a physical phantom. The volume estimation of the phantom by the MSSCD segmentation is to within 13% of the physically determined volume.
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Hergum, Torbjørn. "3D Ultrasound for Quantitative Echocardiography." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for sirkulasjon og bildediagnostikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5937.
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Medical ultrasound imaging is widely used to diagnose cardiacdiseases. The recent availability of real time 3D ultrasound posesseveral interesting challenges and opportunities, and the work of thisthesis is devoted to both challenges and opportunities. One of the key benefits of ultrasound imaging is that its images arereal time. This has been challenged with the recent introduction of 3Dimages, where the number of ultrasound beams is squared compared totraditional 2D images. One common way to alleviate this is byreceiving several closely spaced ultrasound beams from each pulsetransmission, which increases acquisition speed but affects the imagequality. Specifically, B-mode images are irregularly sampled and losespatial shift invariance while a bias in the Doppler velocityestimates causes a discontinuity in the velocity estimates in colorflow images. We have found that these artifacts can be reducedsignificantly by interpolation of the beamformed data from overlappingbeams, with the limitation of requiring at least twice the number ofbeamformers. We have also found that valvular regurgitation is one of thecardiac diseases that can benefit greatly from quantification ofseverity using 3D ultrasound. We have devised a modality that useshigh pulse repetition frequency 3D Doppler to isolate thebackscattered signal power from the vena contracta of a regurgitantjet. This measure is calibrated with a narrow reference beam insidethe jet to estimate the cross-sectional area of the vena contracta. Wehave validated this method with computer simulations, with an in vitrostudy and finally in vivo with 27 patients who had mitralregurgitation. We found that the cross-sectional area and regurgitantvolume of the vena contracta could be quantified without bias as long as the orifice was sufficiently large for a calibration beam tofit inside it. The severity of smaller regurgitations will beoverestimated, but this does not pose a clinical problem, as thesepatients can easily be identified by standard 2D Doppler examination and donot typically need further quantification. Finally, we have developed a new, fast 3D ultrasound simulation methodthat can incorporate anisotropic scattering from cardiac muscle cells. This approach is three orders of magnitudefaster than the most commonly used simulation methods, making it wellsuited for the simulation of dynamic 3D images for development and testingof quantitative diagnostic methods such as 3D speckle tracking andvolumetric measurements.
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Deng, Jing. "Dynamic three-dimensional fetal echocardiography." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412515.
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Pell, Alastair Charles Hamish. "Novel applications of transoesophageal echocardiography." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/20733.
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Transoesophageal echocardiography has become a widely used diagnostic imaging technique by virtue of its ability to yield high quality images of the heart and great vessels. This thesis is based on work performed between January 1991 and July 1992 during which novel applications of transoesophageal echocardiography were investigated in the intraoperative and critical care settings. The mechanism by which closed chest cardiopulmonary resuscitation (CPR) generates forward blood flow has long been debated. Use of transoesophageal echocardiography allowed the physiology of CPR to be elucidated in 18 human subjects with cardiac arrest. These observations supported the cardiac pump theory of CPR and suggested that transoesophageal echocardiography might be utilised to monitor the efficacy of CPR. A preliminary investigation of CPR performed with the active compression-decompression device is described. The pathophysiology of the fat embolism syndrome (FES) is poorly understood. Transoesophageal echocardiography detected intraoperative fat embolism in 24 patients with traumatic injuries, three of whom subsequently developed clinical evidence of FES. Paradoxical embolism through a patent foramen ovale occurred in one subject with fulminating fat embolism. These results support the mechanical theory of the aetiology of fat emboli, and suggest that transoesophageal echocardiography might be used to identify patients at greatest risk of FES. The role of transoesophageal echocardiography in monitoring regional and global myocardial function was explored in a study of the cardioprotective properties of acadesine in patients undergoing coronary artery bypass surgery. No differences were observed between the acadesine and control groups in the incidence of new regional wall motion abnormalities or in changes in the areas ejection fraction. The strengths and limitations of transoesophageal echocardiography are discussed.
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Telford, Lisa Helen. "Standard echocardiography versus handheld echocardiography for the detection of subclinical rheumatic heart disease: A systematic review." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29528.
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Rheumatic heart disease (RHD) is a permanent heart valve condition resulting from an abnormal immune reaction to group A streptococcal (GAS) infection typically occurring in childhood. If left untreated, disease progression can result in irreversible heart valve damage, cardiac failure, stroke and premature death. Significantly, RHD is a preventable and treatable chronic condition which mostly effects disadvantaged populations across the world. Moreover, the continued persistence of RHD contributes to considerable amounts of preventable morbidity and mortality, predominantly among adolescents and young adults. The accurate detection of subclinical RHD in children and adolescents, however, remains hampered by the cost of diagnostic machinery and scarcity of trained personnel. Alternative RHD screening tests, which are both accurate and affordable, are therefore needed in many endemic areas. Recently, handheld echocardiography has become widely available with a variety of clinical uses. If shown to be sufficiently accurate, use of these handheld devices could potentially expand access to echocardiographic screening in RHD endemic areas. The research undertaken for this MPH dissertation compares the accuracy of handheld echocardiography for the detection of rheumatic heart disease to the reference standard using systematic review methods. The dissertation is structured into three parts.
PART A is a research protocol which describes the background and process of the proposed review. This section details the quantitative methods to be used in the systematic review and meta-analysis of studies which assess the diagnostic accuracy of handheld echocardiography for rheumatic heart disease detection in children and adolescents. The proposed systematic review methods are based on those of the Cochrane Collaboration.
PART B is an extended literature review which expands on some of the topics raised in the background section of the protocol. A more in depth insight into the context surrounding the proposed research is offered and its importance highlighted. By reviewing the current body of evidence, this literature review aimed to both describe and contextualise the global burden of rheumatic heart disease whilst providing a rationale for further research into better screening modalities. Similarly, it also sought to describe the importance of understanding rheumatic heart disease epidemiology so that future research and screening programmes may be targeted accordingly.
PART C is a full systematic review of diagnostic test accuracy studies presented as a journal ‘ready’ manuscript in a format suitable for submission to PLoS ONE. The background to the systematic review is briefly summarised after which the results are then presented and discussed. The main findings, from seven included studies, provide some evidence for the potential of handheld echocardiography to increase access to echocardiographic screening for rheumatic heart disease. Lastly and in conclusion, implications arising from the findings of the review are posited and suggestions for future research offered.
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Manser, Sarina. "Wall motion classification of stress echocardiography." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526081.
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黃康素 and Hong-soo Wong. "First trimester fetal echocardiographic normogram." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31970813.
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Patteson, Mark William. "Echocardiographic studies in the horse." Thesis, University of Bristol, 1993. http://hdl.handle.net/1983/ce3af332-cf49-4a90-a0e2-38e6dda12062.
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Storaa, Camilla. "Reproducibility and interpretation in tissue Doppler echocardiography." Doctoral thesis, KTH, Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3818.
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As cardiovascular disease is the single most common cause ofdeath in the western world, and since there is a closeconnection between cardiovascular disease and left ventricular(LV) function, good methods for the assessment of LV functionis highly needed. A widely used tool for the diagnosis of LVdisease is echocardiography, a technique which today faces twodi_culties; the low reproducibility and the subjectiveinterpretation. The present dissertation aims to quantifyreproducibility, to study the factors that influencereproducibility and to provide tools for simplifying theinterpretation of tissue velocities measured by Dopplerultrasound.
The reproducibility has been studied by letting twoindependent observers measure tissue Doppler velocities toinvestigate how well their measurements agree. To improvereproducibility an algorithm for the automatic detection ofpre-defined echocardiographic localizations is presented. Oneof the most difficult skills for the sonographer to master,thus leading to reduced reproducibility, is the transducermanipulation. The effect of poor transducer manipulation hasbeen modeled, and we show that even a poorly placed transducermay yield images which are easily mistaken for good, however,when scanning in two orthogonal planes the transducermisplacement is easily detected.
Interpretation of the echocardiograms is influenced byseveral parameters. As the tissue velocities are measured byutilizing the Doppler effect, only the velocity componentdirected towards the transducer can be measured, thus thealignment of the heart within the view of the transduceraffects the tissue velocity measurements. The effect of thishas been investigated, and it is demonstrated that since themyocardium primarily has longitudinal motion and thus thevelocity vectors are mainly longitudinal, imaging in the apicalview will give little error in the velocity measurements.
Filtering of the tissue velocity signals have becomecommercially available with the hope that it will improvereproducibility and simplify interpretation. One set of lowpass filters has been tested, and it is seen that there is arisk of overdoing the filtering and cause an underestimation oftissue velocity parameters. A similar effect to low passfiltering is seen when using too low sample rate when recordingthe tissue velocities.
Finally a new imaging modality, tissue motion imaging, ispresented, where myocardial displacement, velocity, strain andacceleration may be interpreted from one single image, insteadof the situation today where several measurements must beperformed to get an overview of all these parameters.
The thesis concludes that reproducibility can be improved bycurve smoothing and that interpretation can be simplified usingadvanced methods of parametric imaging.
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Mishra, Mamata. "Clinical and physiological aspects of stress echocardiography." Thesis, Queen Mary, University of London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267303.
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Hang, Xiyi. "Compression and segmentation of three-dimensional echocardiography." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1089835123.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xvii, 151 p.; also includes graphics (some col.). Includes bibliographical references (p. 145-151). Available online via OhioLINK's ETD Center
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Joos, Philippe. "Imagerie ultrasonore ultra-rapide dédiée à la quantification 3D du mouvement cardiaque." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1312/document.
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Cette thèse porte sur le développement et l’évaluation de techniques d’imagerie en échocardiographie. L’objectif est de proposer des méthodes d’imagerie ultrasonore ultrarapide pour estimer le mouvement cardiaque 2-D et 3-D.Première modalité d’imagerie du cœur, l’échocardiographie conventionnelle permet la mesure des déformations myocardiques à 80 images/s. Cette cadence d’imagerie est insuffisante pour quantifier les mouvements de la totalité du myocarde lors de tests d’efforts, utiles en évaluation clinique, au cours desquels le rythme cardiaque est augmenté. De plus, la résolution temporelle actuelle en échocardiographie 3-D limite ses applications, pourtant essentielles pour une caractérisation complète du cœur.Les contributions présentées ici sont 1) le développement et l’évaluation, pour l’application cardiaque, d’une méthode originale d’estimation de mouvement 2-D par imagerie ultrarapide et marquage des images, 2) l’étude de faisabilité de la mesure globale des déformations cardiaques avec une méthode innovante d’imagerie ultrasonore ultrarapide 2-D et 3) la généralisation de cette approche en 3-D pour l’imagerie des volumes cardiaques à haute résolution temporelle. Cette technique est basée sur l’émission d’ondes divergentes, et l’intégration d’une compensation de mouvement dans le processus de formation des volumes cardiaques.La méthode proposée permet l’estimation des mouvements cardiaques 2-D et l’échocardiographie ultrarapide 3-D. L’évaluation de notre approche pour la quantification des déformations myocardiques locales 2-D et 3-D pourrait permettre de proposer des pistes innovantes pour poursuivre nos études et améliorer le diagnostic en routine cliniqueThis PhD work focuses on the development and the evaluation of imaging techniques in echocardiography. Our objective is to propose ultrafast ultrasound imaging methods for 2-D and 3-D cardiac motion estimations.Echocardiography is one of the most widespread modality for cardiovascular imaging. Conventional clinical scanners allow measurement of myocardial velocities and deformations at 80 images / s. In some situations, it can be recommended to increase the heart rate during a stress echocardiographic examination. Motion estimation of the whole myocardium at such heart rates is challenging with the conventional imaging systems. In addition, the low temporal resolution of the current conventional 3-D echocardiography limits quantitative applications, which would be needed for a complete characterization of the heart.The three contributions presented here are 1) the development and evaluation of an original method for 2-D cardiac motion estimation, with ultrafast imaging and image tagging, 2) the feasibility study of the global myocardial deformation measurement using an innovative 2-D ultrafast ultrasound imaging method and 3) the generalization of this approach in three dimensions for high frame-rate 3-D echocardiography. This method is based on the transmission of divergent waves and the integration of motion compensation, during the imaging process, to produce high-quality volumetric images of the heart.The proposed method allows 2-D cardiac motion estimation and 3-D echocardiography at high frame-rate. The evaluation of our approach for local 2-D and 3-D myocardial deformation measurements should permit to conduct further study in order to improve medical diagnosis
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Rajpoot, Kashif. "Multi-view 3D Echocardiographic image analysis." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510207.
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Soliman, Osama Ibrahim Ibrahim. "Advanced quantitative echocardiography: guiding therapy for heart failure." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10652.
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Rhodes, Caroline Lee. "Motion artifact detection in transthoracic 3-D echocardiography." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16719.
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Geenty, Paul. "Echocardiography in Infiltrative Cardiomyopathy: Amyloidosis and Fabry Disease." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/29152.
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The infiltrative cardiomyopathies are a heterogeneous group of disorders classically characterised by increased wall thickness and progressive diastolic dysfunction. While considered relatively rare, they are likely underdiagnosed, and are increasingly recognized as a significant cause of heart failure with preserved ejection fraction, particularly in the case of amyloidosis. Despite varying markedly in their natural histories and treatments available, they are often difficult to distinguish using conventional echocardiographic techniques. For this reason, novel imaging techniques, and multi-modality imaging are playing an increasing role in the diagnosis, prognostication and monitoring of infiltrative cardiomyopathies.
This thesis aims to investigate the role of both conventional and novel echocardiographic techniques in the diagnosis and management of amyloidosis and Fabry disease, two of the more common forms of infiltrative cardiomyopathy.
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Lim, Pascal. "Etude de la mécanique ventriculaire en échographie : modélisation de l'asynchronisme mécanique." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00660675.
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Introduction : La resynchronisation cardiaque (CRT) améliore les patients insuffisants cardiaques, symptomatiques malgré un traitement médical optimal et présentant un élargissement du QRS>120ms. Cependant, un tiers des patients ne répondent pas à cette thérapie. L'objet de cette thèse est d'identifier les mécanismes déterminant la réponse à la CRT. Méthode: Dans un premier temps, nous avons apprécié la précision des méthodes de quantification de la contraction myocardique utilisées pour caractériser l'asynchronisme. Ensuite, nous avons évalué les facteurs liés à l'asynchronisme et à la réponse à la CRT (fibrose, nécrose myocardique, réserve contractile). De plus, nous avons développé et validé un nouvel indice permettant d'évaluer les conséquences " énergétiques " de l'asynchronisme sur la contraction myocardique. Résultats: Nous avons démontré que le strain longitudinal en speckle tracking était supérieur au Doppler tissulaire pour évaluer la déformation et l'asynchronisme myocardique et qu'il était mieux corrélé au pronostic des patients insuffisants cardiaques. Ensuite nous avons mis en évidence que le retard de contraction mécanique n'était pas lié simplement à un bloc de conduction électrique mais qu'il était observé pour l'ensemble des segments myocardiques nécrosés. De plus ces zones de fibrose et de nécrose évaluées en échographie de stress influencent la réponse à la CRT. Ces résultats suggèrent l'importance de considérer le retard de contraction et la contractilité résiduelle pour prédire la réponse à la CRT. A partir de cette hypothèse, nous avons validé un indice unique associant l'asynchronisme et la contractilité résiduelle pour évaluer la perte d'énergie contractile liée au retard de contraction. Conclusion : Les travaux réalisés ont permis de développer des outils pour mieux apprécier les conséquences de l'asynchronisme myocardique.
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Nemes, Attila. "Advances in the evaluation of cardiovascular function by echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10416.
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Kydd, Anna Christine. "Utility of echocardiography in guiding cardiac resynchronisation therapy (CRT)." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709470.
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Roberts, Elved Bryn. "Assessment of coronary artery stenosis using myocardial contrast echocardiography." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1445931/.
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The theoretical advantage of perfusion data over wall motion data for diagnosing coronary artery stenosis relates to the temporal sequence of these phenomena in the ischaemic cascade. Myocardial perfusion evaluation could thus provide earlier information than wall motion assessment, with important clinical consequences. This thesis examines myocardial perfusion assessment using ultrasound and micro-bubble contrast in stable coronary artery stenosis. The first set of experiments were undertaken to establish both a means of infusing Optison (GE Healthcare, UK), and of displaying static frame contrast signal using Power Contrast Imaging (Acuson Sequoia, Siemens Medical Solutions, Mountain View, CA, USA.). Three Optison concentrations, five infusion rates, and five trigger intervals were evaluated. This revealed an appropriate concentration and infusion rate for Optison and identified an ideal trigger interval of one in four cardiac cycles. The second part of this study evaluated Power Contrast Imaging with Optison infusion in stable single or double vessel coronary artery stenosis. Perfusion assessment during Adenosine vasodilator stress was compared with standard wall motion assessment during Dobutamine stress, coronary angiography being the diagnostic standard. Among twenty-eight subjects and eighty-four coronary territories, Power Contrast Imaging had low sensitivity but equivalent specificity compared to wall motion assessment. The third component of this research evaluated micro-bubble preserving real time Coherent Contrast Imaging (Acuson Sequoia , Siemens Medical Solutions) alongside Optison infusion in stable single or double vessel coronary stenosis. Thirty-eight subjects and one hundred and fourteen coronary arteries were evaluated. Each subject underwent Dobutamine stress, during which standard wall motion, contrast wall motion, and contrast perfusion imaging were all assessed, the diagnostic standard being coronary angiography. This demonstrated that contrast wall motion evaluation is accurate and that combined contrast wall motion and perfusion imaging is at least equivalent to standard wall motion imaging alone for detecting underlying coronary stenosis.
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Bedeker, Wiaan Francois. "Impact of basic transthoracic echocardiography at district hospital level." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16935.
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Includes bibliographical referencesThe use and demand of echocardiography has increased worldwide. In developed countries, this has not been translated into improved access outside tertiary centres. Previous studies have favoured the appropriate use of echocardiography over its clinical impact, limiting generalisability to resource constrained settings. Objectives: To assess the impact of an echocardiographic service at district hospital level in Cape Town, South Africa. Methods: A prospective, cross-sectional study was performed. A total of 210consecutive patients, referred to the echocardiography clinic over a five-month period, were recruited. Transthoracic echocardiography was evaluated by its indication, new information provided, correlation with referring doctor's diagnosis and subsequent management plan. Impact included the escalation and de-escalation in treatment, as well as usefulness without a change in management. Results: The results show that 84% of the patients' management was impacted by echocardiography. Valvular lesions were the main indication. The most frequent contribution was information provided towards the diagnosis of heart failure and assessment post-myocardial infarction. Fifty-six per cent of the echocardiograms confirming the referring doctor's diagnosis still had a significant impact. The rational prescription of medication had the major impetus, followed by de-escalation of therapy and screening patients for referral to tertiary facilities. Conclusion: Echocardiography has a positive impact on patient management outside tertiary settings, where the definition of impact appears to be different. The value of a normal study, screening prior to upstream referral and usefulness irrespective of change has been established. This should alert policy makers towards the risk of restricted access and promote training.
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Dedobbeleer, Chantal. "Echocardiographie de déformation et fonction ventriculaire gauche." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209331.
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La dysfonction ventriculaire gauche reste sous-diagnostiquée en pratique clinique actuelle car les paramètres conventionnels d’échographie ne sont pas suffisamment sensibles pour détecter des modifications fines de la fonction cardiaque. L’introduction récente de l’échocardiographie de suivi des marqueurs acoustiques (speckle tracking echocardiography) a permis par ses capacités descriptives de la mécanique cardiaque, de revisiter la contraction cardiaque et, de ce fait, de proposer une nouvelle approche échographique de l’évaluation de la fonction ventriculaire gauche.A travers trois études, nous avons montré que l’analyse des indices de déformation permet d’objectiver des modifications de fonction ventriculaire gauche indétectables en échocardiographie conventionnelle dans des situations complexes à fraction d’éjection conservée, en dépit de l’augmentation modérée de la fréquence cardiaque qui leur est associée. Les situations que nous avons étudiées sont les suivantes :l’adaptation physiologique à l’hypoxie au niveau de la mer et en altitude, et les situations pathologiques que sont le syndrome de mal d’altitude chronique, et la cardiomyopathie associée à l’ataxie de Friedreich.
L’intégration de nos résultats et des informations disponibles dans la littérature permet de suggérer que l’utilisation de toutes les ressources offertes par l’échocardiographie de suivi des marqueurs acoustiques permet d’améliorer l’évaluation de la fonction cardiaque au-delà de la fraction d’éjection, en offrant une meilleure identification de situations pathologiques mais également une meilleure compréhension de situations physiologiques et pathologiques.
L’utilisation généralisée des indices de déformation pour l’évaluation de la fonction ventriculaire gauche en pratique clinique connaît néanmoins d’importantes limitations que nous abordons dans la discussion de ce travail. Au terme d’investigations complémentaires et de standardisation de la technique, l’incorporation d’un algorithme d’évaluation échographique de la fonction cardiaque à FEVG conservée combinant les paramètres échographiques conventionnels et les indices de déformation pourra être évalué de façon prospective pour sa translation en pratique clinique, avec pour finalité la proposition d’une définition mieux adaptée de l’insuffisance cardiaque à FEVG conservée.
Doctorat en Sciences médicales
info:eu-repo/semantics/nonPublished
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Dobson, Rebecca. "Carcinoid heart disease : biochemical and echocardiographic assessment." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3003352/.
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Introduction: Carcinoid heart disease is a para-neoplastic complication of neuroendocrine tumours, occurring in patients with carcinoid syndrome. Due perhaps to its rarity, there is conflicting evidence in the literature with regard to the optimum method of diagnosis and assessment of the condition. The aim of this thesis is to quantify the variation in clinical practice with regard to carcinoid heart disease and to identify the optimum biochemical and echocardiographic methods for the screening, diagnosis and assessment of progression of the condition. Methods: Patients were prospectively recruited from specialist neuroendocrine clinics in the North of England and underwent evaluation of their symptoms, disease burden, biochemical markers, and transthoracic echocardiography. Results: Wide variation in the screening and clinical management of carcinoid heart disease was identified. A total of 239 patients were recruited to the study and the prevalence of carcinoid heart disease was 21%. From a panel of biomarkers, N-terminal pro brain natriuretic peptide (NTproBNP) and plasma 5-hydroxyindoleacetic acid (5HIAA) were the most sensitive and specific biomarkers for the presence of carcinoid heart disease. All previously described echocardiographic scoring systems discriminated highly between those with/without carcinoid heart disease, with no single score performing significantly better than another. The complexity of the scoring systems varied considerably, with the simplest scoring system better suited for screening and the more complex systems most useful for pre-surgical assessment. A disease progression rate of 9% was demonstrated, with a further 22% of patients dying during the study. Plasma 5HIAA was the greatest predictor of disease progression and death. Conclusion: There is considerable heterogeneity across the UK and Ireland in multiple aspects of screening and management of carcinoid heart disease. NTproBNP and plasma 5HIAA should be used to screen for the disease with transthoracic echocardiography reserved for those with elevated biomarkers. A simple echocardiographic scoring system should be used to screen for the disease, with the more complex scoring systems reserved for those patients with established disease. Biomarkers can also be used to predict risk of disease progression and death.
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Damerjian, Vera. "La caractérisation du speckle sur des images échocardiographiques afin de définir des indices diagnostiques de l'amylose cardiaque et personnaliser un modèle numérique du coeur." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1035.
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L’Hypertrophie Ventriculaire Gauche (HVG) est actuellement mise en évidence par échographie. Cet examen fournit des informations anatomo-fonctionnelles mais ne permet pas de déterminer l’étiologie des HVG, ce qui engendre de graves erreurs de diagnostic et de prise en charge thérapeutique. Les HVG sont classiquement séparées en 2 catégories :1. pathologies hypertrophiques induites par la modification structurelle et fonctionnelle des cardiomyocites qui tend à compenser des insuffisances cardiaques liées par exemple à des problèmes d’hypertension artérielle, de rétrécissement aortique ou de CardioMyopathies Hypertrophiques sarcomériques ;2. pathologies infiltratives correspondant au dépôt de protéines dans la matriceextracellulaire principalement dues à différentes formes d’amyloses cardiaquesNotre hypothèse est que les différents mécanismes physiopathologiques (hypertrophique ou infiltratif) pourraient se traduire dans l’image par des propriétés spécifiques du speckle échographique. Nous avons donc développé un travail d’analyse de la texture de ces images afin de discriminer les différentes HVG.Dans cette étude, la base de données de 4795 images est divisée en une base d’apprentissage de 3770 images et une base de test de 1025 images. L’analyse de texture des images est faite par les ondelettes de Gabor avec 8 orientations, 7 tailles et 5 niveaux de décomposition. Ensuite, les caractéristiques statistiques de premier et deuxième ordre sont extraites des images. Le nombre des caractéristiques est réduit pour la base d’apprentissage en appliquant l’Analyse en Composantes Principales (ACP) suivie par l’analyse discriminante linéaire (ADL) pour une séparation supervisée des classes. Les caractéristiques extraites pour la base de test sont projetées sur les vecteurs propres sélectionnés au cours de l’apprentissage. L’ADL est appliquée à ce niveau pour la classification des données du test et la qualité de cette classification est évaluée. Les résultats obtenus sont bons (qualité totale de classification de 95,51%) et sont suivis d’une étape de cross-validation afin de vérifier la robustesse de notre méthode. A cette étape, les bases de données de l’apprentissage et du test sont mélangées et 50 combinaisons différentes sont évaluées. La même méthode décrite précédemment est appliquée. La cross-validation montre une variation de la qualité de classification (entre 30% et 99.96%) probablement due à l’hétérogénéité des caractéristiques texturelles pour les patients d’une même classe que l’on peut expliquer par des degrés différents d’avancement dans la pathologie.Ces travaux montrent qu’une analyse de texture des images échocardiographiques peut permettre de déterminer des bio-marqueurs aptes à discriminer différentes cardiopathies qui s’expriment par une HVG. Ce résultat peut avoir des retombées très importantes dans la détection précoce des amyloses cardiaques, maladies engendrant un fort taux de mortalité souvent dû à un retard de diagnostic et prise en charge des patients par un centre expertLeft-Ventricular Hypertrophy (LVH) is currently detected through echocardiography. The latter imaging modality provides anatomical and functional information. However, it does not allow the determination of the HVG etiology. This can, in turn, lead to dangerous errors in the diagnosis and treatment planning of the disease. LVH pathologies are separated into two categories:- Hypertrophic pathology caused by the structural and functional modification of cardiomyocytes that lead to cardiac failure related, for example, to arterial hypertension problems, aortic narrowing or sarcomeric hypertrophic cardiomyopathies.- Infiltrative pathologies corresponding to protein deposits on the extracellular matrix, mainly due to different forms of cardiac amyloidosisOur hypothesis is that different physiopathological mechanisms (hypertrophic or infiltrative) can be translated in the image through properties specific to echographic speckle. We have therefore developed the work of texture analysis of such images in order to discriminate the different types of LVH.In this study, the database of 4795 images is divided into a learning database of 3770 images and another testing database of 1025 images. The textural analysis of these images is done using Gabor wavelets with 8 orientations, 7 sizes and 5 decomposition levels. Next, the statistical characteristics of first and second orders are extracted from the filtered images. The number of characteristics is reduced for the learning database by applying Principal Component Analysis (PCA) followed by Linear Discriminant Analysis (LDA) for a supervised separation of the classes. The extracted characteristics for the test database are projected on the eigenvectors selected in the learning step. LDA is applied at this level for the test data classification, and the quality of this classification is evaluated. The obtained results are good (total classification quality of 95.51%). A step of cross-validation follows in order to verify the robustness of our method. At this stage, the learning and testing databases are mixed, and 50 different combinations are evaluated. The same method described previously is then applied. The cross-validation shows a variation in the classification quality (between 30% and 99.96%) probably due to the heterogeneity of the texture characteristics for the patients of the same class explained by different disease advancement stages.This work shows that the textural analysis of echocardiographic images can permit the determination of bio-markers suitable to discriminate different LVH cardiopathies. Our results can have a very important impact on the early detection of cardiac amyloidosis, a pathology causing a considerable rate of mortality often due to a belated diagnosis and support by the centers of expertise
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Palmgren, Ingrid. "Transesophageal Echocardiography in Patients Undergoing Elective Coronary Artery Bypass Surgery." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5238-8/.
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Zabair, Adeala Tuffail. "Segmentation of stress echocardiography sequences using a patient-specific prior." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534181.
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Amini, Richard, Lori Stolz, Parisa Javedani, Kevin Gaskin, Nicola Baker, Vivienne Ng, and Srikar Adhikari. "Point-of-care echocardiography in simulation-based education and assessment." DOVE MEDICAL PRESS LTD, 2016. http://hdl.handle.net/10150/614981.
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Background: Emergency medicine milestones released by the Accreditation Council for Graduate Medical Education require residents to demonstrate competency in bedside ultrasound (US). The acquisition of these skills necessitates a combination of exposure to clinical pathology, hands-on US training, and feedback. Objectives: We describe a novel simulation-based educational and assessment tool designed to evaluate emergency medicine residents' competency in point-of-care echocardiography for evaluation of a hypotensive patient with chest pain using bedside US. Methods: This was a cross-sectional study conducted at an academic medical center. A simulation-based module was developed to teach and assess the use of point-of-care echocardiography in the evaluation of the hypotensive patient. The focus of this module was sonographic imaging of cardiac pathology, and this focus was incorporated in all components of the session: asynchronous learning, didactic lecture, case-based learning, and hands-on stations. Results: A total of 52 residents with varying US experience participated in this study. Questions focused on knowledge assessment demonstrated improvement across the postgraduate year (PGY) of training. Objective standardized clinical examination evaluation demonstrated improvement between PGY I and PGY III; however, it was noted that there was a small dip in hands-on scanning skills during the PGY II. Clinical diagnosis and management skills also demonstrated incremental improvement across the PGY of training. Conclusion: The 1-day, simulation-based US workshop was an effective educational and assessment tool at our institution.
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Amini, Richard, Lori A. Stolz, Parisa P. Javedani, Kevin Gaskin, Nicola Baker, Vivienne Ng, and Srikar Adhikari. "Point-of-care echocardiography in simulation-based education and assessment." Dove Press, 2016. http://hdl.handle.net/10150/617183.
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UA Open Access Publishing FundBackground: Emergency medicine milestones released by the Accreditation Council for Graduate Medical Education require residents to demonstrate competency in bedside ultrasound (US). The acquisition of these skills necessitates a combination of exposure to clinical pathology, hands-on US training, and feedback. Objectives: We describe a novel simulation-based educational and assessment tool designed to evaluate emergency medicine residents’ competency in point-of-care echocardiography for evaluation of a hypotensive patient with chest pain using bedside US. Methods: This was a cross-sectional study conducted at an academic medical center. A simulation-based module was developed to teach and assess the use of point-of-care echocardiography in the evaluation of the hypotensive patient. The focus of this module was sonographic imaging of cardiac pathology, and this focus was incorporated in all components of the session: asynchronous learning, didactic lecture, case-based learning, and hands-on stations. Results: A total of 52 residents with varying US experience participated in this study. Questions focused on knowledge assessment demonstrated improvement across the postgraduate year (PGY) of training. Objective standardized clinical examination evaluation demonstrated improvement between PGY I and PGY III; however, it was noted that there was a small dip in hands-on scanning skills during the PGY II. Clinical diagnosis and management skills also demonstrated incremental improvement across the PGY of training. Conclusion: The 1-day, simulation-based US workshop was an effective educational and assessment tool at our institution.
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Pudiak, Kh I. "Cardiovascular complications according to echocardiography among asymptomatic HIV-infected patients." Thesis, БДМУ, 2020. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18224.
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Radin, Umar Radin Zaid. "Ergonomic Interventional Design of an Articulated Arm for Echocardiography Application." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1293678856.
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Li, Xiang-Ning. "Quantitative assessment of mitral regurgitation with three-dimensional doppler echocardiography /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8039.
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Finel, Victor. "3D ultrafast echocardiography : toward a quantitative imaging of the myocardium." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC134/document.
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L’objectif de cette thèse de doctorat était de développer l’échographie ultrarapide 3D du cœur, plus particulièrement dans le but de caractériser le muscle cardiaque. A cet effet, un échographe ultrarapide assemblé dans notre laboratoire a été utilisé. Dans la première partie de cette thèse, un mode d’imagerie temps-réel a été développé pour faciliter l’imagerie in-vivo en utilisant ce scanner, ainsi que des outils de visualisation 3D et 4D. Par la suite, l’imagerie 3D du tenseur de rétrodiffusion a été développée pour analyser l’orientation des fibres musculaires du cœur de manière non-invasive au cours du cycle cardiaque. Des résultats obtenus sur un volontaire avant et après la contraction cardiaque ont été obtenus. De plus, les effets indésirables du mouvement axial ont été étudiés, et une méthode d’estimation de la vitesse axiale et de correction des aberrations induites a été proposée et appliquée sur l’homme. Cette technique pourrait devenir un outil intéressant de diagnostic et quantification de la désorganisation des fibres musculaires dans le cadre de cardiomyopathies hypertrophiques. De plus, l’échographie ultrarapide 3D a été utilisée pour visualiser la propagation dans les parois du cœur d’ondes de cisaillement générées naturellement au cours du cycle cardiaque, et un algorithme pour déterminer leurs vitesses a été développé. Cette technique a été validée grâce à des simulations numériques puis appliquée sur deux volontaires sains, pendant les phases de contraction et relaxation du myocarde. Etant donné que la vitesse des ondes de cisaillement est directement reliée à la rigidité du cœur, cette méthode pourrait permettre d’estimer la capacité du cœur à de contracter et à se relâcher, qui sont des paramètres important pour son fonctionnement. Enfin, l’activation de la contraction cardiaque de cœurs de rats isolés a été imagée à haute cadence et en 3D dans le but d’analyser la synchronisation de la contraction. Les délais d’activation mécanique ont pu correctement être quantifiés lors du rythme naturel du cœur, de stimulations électriques extérieures ainsi qu’en hypothermie. Ensuite, la faisabilité de la technique en 2D sur des cœurs humains de manière non-invasive a été étudiée et appliquée sur des fœtus et des adultes. Cette technique d’imagerie pourrait aider la caractérisation d’arythmies et améliorer leur traitement. En conclusion, nous avons introduit dans ces travaux de thèse trois nouvelles modalités d’imagerie ultrarapide 3D permettant de quantifier des propriétés structurelles et fonctionnelles du myocarde qui jusqu’ici ne pouvaient pas être imagée en échocardiographie. L’imagerie 3D ultrarapide est une modalité très prometteuse, non ionisante, transportable et qui pourrait améliorer fortement dans le futur le diagnostic et la prise en charge des patientsThe objectives of this PhD thesis were to develop 3D ultrafast ultrasound imaging of the human heart toward the characterization of cardiac tissues. In order to do so, a customized, programmable, ultrafast scanner built in our group was used. In the first part of this thesis, a real-time imaging sequence was developed to facilitate in-vivo imaging using this scanner, as well as dedicated 3D and 4D visualization tools. Then, we developed 3D Backscatter Tensor Imaging (BTI), a technique to visualize the muscular fibres orientation within the heart wall non-invasively during the cardiac cycle. Applications on a healthy volunteer before and after cardiac contraction was shown. Moreover, the undesired effects of axial motion on BTI were studied, and a methodology to estimate motion velocity and reduce the undesired affects was introduced and applied on a healthy volunteer. This technique may become an interesting tool for the diagnosis and quantification of fibres disarrays in hypertrophic cardiomyopathies. Moreover, 3D ultrafast ultrasound was used to image the propagation of naturally generated shear waves in the heart walls, and an algorithm to determine their speed was developed. The technique was validated in silico and the in vivo feasibility was shown on two healthy volunteers, during cardiac contraction and relaxation. As the velocity of shear waves is directly related to the rigidity of the heart, this technique could be a way to assess the ability of the ventricle to contract and relax, which is an important parameter for cardiac function evaluation. Finally, the transient myocardial contraction was imaged in 3D on isolated rat hearts at high framerate in order to analyse the contraction sequence. Mechanical activation delays were successfully quantified during natural rhythm, pacing and hypothermia. Then, the feasibility of the technique in 2D on human hearts non-invasively was investigated. Applications on foetuses and adults hearts were shown. This imaging technique may help the characterization of cardiac arrhythmias and thus improve their treatment. In conclusion, we have introduced in this work three novel 3D ultrafast imaging modalities for the quantification of structural and functional myocardial properties. 3D ultrafast imaging may become an important non-ionizing, transportable diagnostic tool that may improve the patient care at the bed side
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Belous, Gregg R. "Novel Machine Learning Techniques for Left Ventricular Analysis in Echocardiography." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/400568.
Full textAbstract:
Transthoracic (TTX) echocardiography (echo) is vital for the diagnosis and treatment of heart disease. It is also essential for the determination of appropriate therapeutic procedures and monitoring disease progression and response. An important requisite of TTX echo is the quantitative assessment of left ventricular (LV) size and function from its manually traced endocardial border. However, the diagnostic accuracy of this routine task is often adversely affected by artifact and signal dropout, producing substantial observer variability and uncertainty in clinical diagnosis. With the advent of machine learning, computer aided detection (CAD) systems have addressed organ segmentation through robust landmark localization techniques and a reliance on anatomical shape prior models to guide the segmentation process. Shape priors models are most effective when shape variations can be captured by a parametric distribution, and suffcient training data is available. However, in the absence of these conditions, results are invariably much poorer. In addition, the problem of insuffcient training data not only presents challenges to shape prior models, but also classification algorithms, as well.
Stress echo (SE) is a widely used functional test for the detection of obstructive coronary artery disease. The interpretive process involves the careful comparison of pre- and post-exercise echo sequences across a number of echocardiographic views. This is a time consuming and highly subjective task. While CAD systems have been shown to be feasible for automated reporting in other areas of medical imaging, they have not been applied to the task of identifying abnormal stress echocardiograms. An automated approach would not only be a useful adjunct to physicians reporting SE, but also aid in physician training of SE reporting.
Motivated by these challenges, this thesis presents four novel machine learning techniques for LV analysis in echo. Firstly, two anatomical shape prior models are proposed: online relational manifold learning (ORML) and dual subspace segment projection learning (DSSPL). ORML is formulated to address the challenge of modelling complex shape subspaces. ORML serves to learn a mapping function between a low dimension image manifold and shape manifold. However, different to existing subspace learning approaches, ORML leverages the input image to target more contextually relevant regions between both manifold structures, leading to robust LV shape inference for volume prediction, and the formulation of a shape prior model through a more principled shape selection strategy. ORML demonstrates improved segmentation performance over current benchmark methods, and shows an excellent level of agreement with an expert.
DSSPL addresses the challenges of modelling complex shape variations under the scenario of high dimension low sample size (HDLSS) training data. It serves to compose shapes from an ensemble of shape segments where each segment is formed using two subspaces: global shape subspace and segment-specific subspace, each necessary for extracting global shape patterns and local patterns, respectively. This ensures general shape plausibility in regions of signal drop-out or missing boundary information, and also more localized flexibility. The reconstructive properties of DSSPL reduces information loss and leverages the subspaces to provide contiguous shapes without any post-processing. Comprehensive experimental analysis is performed on three databases from different medical imaging systems across X-Ray, MRI, and echo. DSSPL outperforms all compared benchmarks in terms of its shape generalization ability and segmentation performance.
The third method proposed is dual subspace discriminative projection learning (DSDPL), which addresses the challenge of image classification, also under the HDLSS training data scenario. Unlike traditional projection learning frameworks that assume discriminative features share a common subspace, DSDPL instead serves to decompose original high dimensional data, via learned projection matrices, into class-shared and class-specific subspaces. The learned projection matrices are jointly constrained with l2;1 sparse norm and LDA terms while the reconstructive properties reduce information loss. Regression-based terms are also included to facilitate a more robust classification approach, using extracted class-specific features for better classification. Results show improved classification accuracy with DSDPL over current benchmark subspace learning methods and deep learning models.
The fourth method proposed is deep stage-coupled attentive feature extraction (DSCAFE) for identifying abnormal stress echocardiograms. DSCAFE is a deep neural network model that consists of stage-coupled attentive feature extraction (SCAFE) blocks for extracting the most salient information from connected echo sequences. SCAFE blocks are composed of 3D residual network streams and dual-attention gated mechanisms, which provide more targeted focus across each echo sequence by also taking into account the observed features from the corresponding view at the opposing exercise stage. A recurrent neural network feature aggregation strategy is then employed to model the extracted low dimension spatio-temporal features for more accurate classification. When compared against an expert reviewer, DSCAFE achieved a concordance of 86.5% from a clinical SE dataset. This research draws on machine learning knowledge across a diverse range of domains. While results show definitive improvements over current benchmark methods for LV analysis, the proposed methods are also adaptable to a wide range of computer vision tasks.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Orde, Sam. "Use of advanced echocardiography imaging techniques in the critically ill." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21623.
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Background: Critical care echocardiography has become standard of care in the ICU. New technologies have been developed and have shown potential clinical utility to elucidate myocardial dysfunction not seen with conventional imaging. We sought to determine the feasibility and potential clinical benefit of these techniques in common situations seen in the ICU. Hypothesis: Advanced echo techniques would be feasible in the majority of critically ill patients and have prognostic significance, clinical utility and diagnose cardiac abnormalities, potentially in a more sensitive manner than conventional techniques. Results: (a) Speckle tracking echocardiography (STE) Left ventricle and RV analysis with STE was feasibly in ~80% of patients. More dysfunction was found using STE vs conventional analysis. RV dysfunction assessed by STE held significant prognostic relevance in those with septic shock and highlighted subtle dysfunction induced by mechanical ventilation, both in animal and human studies. (b) 3D transthoracic echocardiography (3D TTE) Despite finding 3D TTE feasible in mechanically ventilated ICU patients (LV 72% and RV 55%), it lacked necessary low variability and high precision vs standard measures. (c) Myocardial contrast perfusion echocardiography (MCPE) Assessing acute coronary artery occlusion in the ICU patient is challenging. Troponin elevation, acute ECG changes, regional wall motion analysis on echo and overall clinical acumen often lack diagnostic capabilities. MCPE was found to be feasible in the critically ill and had better association predicting acute coronary artery occlusion vs clinical acumen alone. Conclusions: STE, 3D TTE and MCPE are feasible in the majority of ICU patients. STE may show dysfunction not recognised by conventional imaging. 3D TTE for volumetric analysis is likely not suitable for clinical use at this stage. MCPE may help guide interventions in acute coronary artery occlusion.
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MONTILLA-LEON, GUILLERMO. "Analyse spatio-temporelle de sequences d'images en echocardiographie." Rennes 1, 1994. http://www.theses.fr/1996REN10100.
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Ce travail porte sur l'analyse des images cardiaques obtenues par ultrasons. Dans cette etude, nous abordons les trois aspects suivant: reconnaissance de formes, mobilite, et caracterisation. La reconnaissance des parois cardiaques est realisee avec des modeles parametriques qui s'adaptent a l'anatomie des cavites cardiaques. Un modele ellipsoidal a 4 parametres est suffisant pour reconnaitre l'epicarde sur la vue parsternale axe court et un modele de type spline a 10 parametres suffit pour l'endocarde sur la vue apicale de 4 chambres. Un algorithme genetique fait evoluer un ensemble de solutions initiales choisies de facon aleatoire jusqu'a obtenir une population hautement specialisee a partir de laquelle une solution optimale est selectionnee. La robustesse de la methode est demontree dans des conditions d'images typiques d'echocardiographie: des images peu contrastees, noyees dans le bruit et ou les parois sont partiellement tronquees. L'etude de la mobilite est basee sur les methodes de champs de vitesse et la mise en correspondance. A partir de ces methodes, on extrait le mouvement des parois au cours du cycle cardiaque, ainsi on obtient la distribution spatiale du deplacement des parois cardiaques. On accede a la visualisation, impossible dans le mode m, en utilisant une interpolation temporelle basee sur les champs de vitesse. L'etude de la mobilite basee sur la technique de mise en correspondance 1d est utilisee pour obtenir la forme temporelle du mouvement des parois. La caracterisation des tissus est l'aspect le plus difficile et de plus grande importance. L'objectif du travail en caracterisation est centre sur la recherche des parametres de texture qui varient au rythme du cycle cardiaque malgre le bruit present dans l'image et celui implique par la methode. On obtient ainsi des parametres deduits des bi-differences et de l'analyse dans le plan frequentiel basee sur les filtres de gabor
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Wesselowski, Sonya Rae. "Echocardiographic Investigation of Canine Myxomatous Mitral Valvular Disease." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49538.
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Objectives: To further characterize the echocardiographic anatomy of the canine mitral valve in healthy dogs and those affected by myxomatous mitral valve disease (MMVD), and to compare the level of agreement between two methods of assessment of left atrial size in identification of left atrial enlargement in dogs with MMVD.
Animals: Sixty dogs with MMVD and 22 normal dogs were prospectively studied with 2-dimensional echocardiography.
Methods: The length (AMVL), width (AMVW) and area (AMVA) of the anterior mitral valve leaflet and the diameter of the mitral valve annulus in systole (MVAs) and diastole (MVAd) were measured. Left atrial size was evaluated with the left atrial to aortic root ratio (LA:Ao) and by measuring left atrial volume indexed to body weight (LA Vol/BW). All patients were staged using published ACVIM guidelines and separated into groups B1 and B2/C.
Results: Measurements of AMVL, AMVW, AMVA, MVAs and MVAd were all significantly greater in the B2/C group than in the control group. AMVW was significantly greater in group B1 than control. Twelve dogs had left atrial enlargement identified with LA Vol/BW that were considered normal using LA:Ao. Diagnostic disagreement between these two measurements was significant (P = 0.00012). The majority of dogs with diagnostic disagreement had concurrent echocardiographic evidence of more advanced mitral regurgitation.
Conclusions: Relative to normal dogs, AMVL, AMVW, AMVA, MVAs and MVAd are greater in patients with advanced MMVD. LA Vol/BW may be superior to LA:Ao for identification of mild left atrial enlargement.Master of Science
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Iqbal, Hena. "Diastolic echocardiographic parameters in patients with atrial fibrillation." Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-26051.
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Vid flertalet hjärtsjukdomar kan det förekomma störningar i den diastoliska funktionen, detta tillstånd benämns diastolisk dysfunktion. Detta innebär att fyllnadstrycken i vänsterkammare ökar på grund av nedsatt eftergivlighet i kammaren. Bedömning av diastolisk funktion, hos patienter som utvecklat förmaksflimmer, är en utmaning inom ekokardiografi. Detta beror på att förmaksflimmer innebär utebliven förmakskontraktion, oregelbunden längd av hjärtcykeln och förmaksdilatation, vilket försvårar bedömningen. Syftet med studien var att med ekokardiografi studera diastoliska parametrar hos patienter med förmaksflimmer för att studera om dessa kan användas vid bedömning av den diastoliska vänsterkammarfunktionen hos denna patientgrupp. I studien inkluderades 37 deltagare med förmaksflimmer som var remitterade för en ekokardiografisk undersökning med olika frågeställningar. Pulsad doppler teknik och vävnads doppler teknik användes för att registrera följande diastoliska parametrar: förmaksvolym, mitralisinflöde (E-vågshastigheten) och myokardiets diastoliska hastigheter (e´). Utöver dessa uppskattades även ejektionsfraktion, hjärtfrekvens, hypertrofi och trycket i lilla kretsloppet, som togs med vid bedömningen. Mann-Whitneys test visade att det förelåg ett starkt statistiskt samband mellan fyllnadstrycket (E/e´) och E-vågen, e ´samt förmaksvolym (p = <0,05). Signifikant resultat erhölls även för sambandet mellan PA-tryck och fyllnadstryck (p = 0,014) genom ett chitvå-test. Vidare gav multipel linjär regression utslag på E-vågen och e´. Analysen visade att det förelåg en hög förklaringsgrad för E-vågen (p = <0,001) och e´ (p = 0,008). Sammanfattningsvis visade resultaten att ekokardiografi kan användas för diagnostik av förmaksflimmerpatienter avseende fyllnadstryck där förmaksvolym, E-vågshastigheten och e´ anses vara bästa parametrarna.In the majority of heart diseases disturbances in the diastolic function may occur, this condition is called diastolic dysfunction. This means that the left ventricular filling pressure increases due to reduced compliance in the chamber. The assessment of diastolic function in patients who have developed atrial fibrillation (AF), is a challenge in echocardiography. This is a result of AF which involves absence of atrial contraction, irregular length of the cardiac cycle and left atrium dilatation that complicates the assessment. The aim of this study was to observe the diastolic echocardiographic parameters in patients with AF to examine if these can be used in the assessment of diastolic left ventricular function in this population. The study included 37 participants with AF who were remitted for an echocardiographic examination due to various concerns. Pulsed Doppler technique and tissue Doppler technique was used to record the following diastolic parameters: atrial volume, mitral inflow velocity (E) and the myocardial diastolic velocity (e'). Ejection fraction, heart-rate, hypertrophy and pulmonary artery pressure were also estimated and included in the assessment. Mann-Whitneys test showed that there was a strong statistical correlation between the filling pressure (E/e') and E, e' and atrial volume (p = <0.05). Significant results were also obtained for the relation between pulmonary artery pressure and the filling pressure (p = 0.014) by a chi-square test. A multiple linear regression showed association between E and e'. The analysis showed that there was a significant value of coefficient of determination for E (p = <0.001) and e' (p = 0.008). In conclusion, the results showed that echocardiography can be used for diagnosis of AF patients regarding filling pressures, where atrial volume, E velocity and e' are considered to be the best parameters.
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Eckerle, Bryan. "Prevalence of Echocardiographic Abnormalities in Acute Ischemic Stroke." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1459528281.
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Luckie, Matthew. "Echocardiographic parameters of dyssynchrony in cardiac resynchronisation therapy." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/echocardiographic-parameters-of-dyssynchrony-in-cardiac-resynchronisation-therapy(8e708f33-f6d1-4941-8de6-45cf14cb54eb).html.
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Background: Cardiac resynchronisation therapy (CRT) is a pacemaker-based therapy for patients with heart failure and dyssynchrony manifest as prolonged QRS duration. Approximately 30% fail to respond either symptomatically or echocardiographically. The role of several echocardiographic parameters to select patients and improve response rate has been studied. The utility of these parameters remains unclear. In particular recent advances in echocardiography with speckle tracking technology may provide more accurate assessment of dyssynchrony. This study aims to explore the role of echocardiography in prediction of CRT response and investigate mechanisms involved in response.Methods:Patients undergoing CRT according to national guidance were recruited. Baseline assessment included clinical examination, quality of life questionnaire, six minute walk test, electrocardiogram and detailed echocardiography. Follow-up assessment was performed six months after CRT. Response was defined as ≥15% reduction in left ventricular end-systolic volume. Baseline parameters of echocardiographic dyssynchrony were compared between responders and non-responders. Individual baseline and follow-up echocardiograms also were examined to assess mechanism of response.Results:51 patients were recruited and 40 patients completed six months follow-up. Echocardiographic response rate was 67.5%. Baseline parameters of dyssynchrony were not significantly different between responders and non-responders, and receiver operating characteristic (ROC) curve analysis suggested echocardiographic parameters have no role in prediction of response beyond QRS duration. Study of individual echocardiograms demonstrated several mechanisms of CRT response the relative importance of which vary between patients.Conclusion:Single echocardiographic dyssynchrony parameters appear to have no role in the prediction of CRT response. However, several mechanisms of response to CRT are identified, each of which may be identified echocardiographically, and echocardiography therefore continues to have an important role in pre-assessment of patients undergoing CRT.