The primary objective of antenatal assessment and monitoring is to ensure wellbeing of the fetus and the mother. There are different methods of assessment during pregnancy and in labour. Doppler ultrasound is one of the tests widely used in clinical practice in the evaluation of pregnancies that are at a greater risk of developing maternal or fetal complications due to uteroplacental insufficiency. Doppler ultrasound enables evaluation of sequential changes in circulatory haemodynamics in the fetus by evaluation of the fetus for signs of brain sparing and severity of redistribution of circulation. Recognition of abnormal Doppler flow patterns helps the clinician to optimise the appropriate timing of delivery. Identification of the ‘high risk’ fetus, before any changes of fetal compromise become evident, still remains one of the major dilemmas in contemporary clinical practice. This thesis seeks to explore the role of Doppler monitoring fetal intrauterine central shunts as a method of identifying the ‘high-risk’ fetus before any other established parameters, such as, fetal biometry, fetal weight or flow waveforms in umbilical artery become abnormal. This thesis also evaluates the role of serial Doppler monitoring of fetal central shunts in those fetuses where IUGR has been established. This is based on the premise that the intrauterine shunts are present in fetal circulation to work closely with the placenta to ensure appropriate nutrition and oxygenation of the fetus, bypassing the lungs. Four prospective longitudinal studies were designed to evaluate the role of fetal intrauterine shunts in adaptive response mechanisms in cardiovascular stress. Two models were taken into consideration: an ‘acute cardiovascular stress’ model and a ‘chronic cardiovascular stress’ model. To study the ‘response to acute cardiovascular stress’ in high-risk fetuses, a cohort of mothers undergoing fetal intrauterine transfusion for fetal anaemia were selected. These fetuses were scanned immediately before and after transfusion, and Doppler flows through all the intrauterine shunts were documented and compared with fetoplacental and cerebral circulation. To study the ‘response to chronic cardiovascular stress’, a prospective longitudinal observational study was designed and the sequence of changes in Doppler ultrasound of the fetal central shunts studied and compared with the Doppler flow waveforms of normal pregnancies with a group of pregnancies complicated by uteroplacental insufficiency. Normograms were designed for all the Doppler parameters and flows from adverse pregnancy outcomes were compared to the normogram. The pregnancy outcomes in the longitudinal study were correlated with placental pathology. Our study showed that although changes were demonstrated in the flow patterns within central shunts, these changes were not statistically significant in the ‘acute cardiovascular stress model’, suggesting that there may be other haemodynamic alterations in acute cardiovascular stress. However, in the ‘chronic cardiovascular stress model’, the results suggest that the intrauterine cardiac shunts may play an important role in redistribution of fetal flows in early stages of growth restriction, suggesting that Doppler ultrasound monitoring of foramen ovale can be potentially used as a screening tool to identify high-risk fetuses as early as 16 weeks. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1349883 / Thesis (Ph.D.) - University of Adelaide, School of Paediatrics and Reproductive Health, 2009

The goal of this study was to derive a clinical prediction rule for transient ischemic attack (TIA) and non-disabling stroke to predict a treatment change based on echocardiogram. Methods: We conducted a cohort sub-study for TIA and non-disabling stroke patients collected over five years from 8 Emergency Departments. We compiled a list of 27 potential predictors to look for treatment change based on echocardiogram findings. We used a univariate, logistic regression and recursive partitioning analysis to develop the final prediction model. Results: The frequency of treatment change was seen in 87 (3.1%) of 2804 cases. The final model contains six predictors: age less than 50 years old, coronary artery disease history, history of heart failure, any language deficit, posterior circulation infarct and middle cerebral artery infarct on neuroimaging. Conclusions: We have developed a highly sensitive clinic prediction rule to guide in the use of echocardiogram in TIA and non-disabling stroke.

No description available.

Heart disease is one of the primary causes of morbidity and mortality for the adult population over the age of 65. Furthermore, ailments such as hypertension can affect as many as 50% of the adult population over the age of 45. If left untreated, these ailments eventually precipitate the onset of diastolic dysfunction and heart failure. Diastolic dysfunction is the alteration or impairment of performance in either the left or right ventricle of the heart. Although there has been a marked increase in study of this disease, there is still an apparent difficulty to diagnose patients. Flow visualization techniques have been commonly employed to study the development of these diseases as they relate to the filling process of the ventricles. One method, Echo Particle Image Velocimetry (Echo-PIV) is a relatively new method for cardiac flow chamber visualization, with the potential to provide physicians with a cost-effective and safe method for obtaining high temporal resolution recordings for extending knowledge on the filling processes in cardiac chamber flow. This work presents a new approach to extending the capabilities of Echo-PIV for more accurate measurement of cardiac flows for patients with poor quality recordings. Currently, much of the literature notes that temporal resolution and poor acoustic windows results in exclusion from study. These recordings are more representative of the contrast-enhancement studies used by physicians to better identify chamber walls. When applying standard PIV cross-correlation techniques, measurements tend to fail due to image noise and artifacts. By implementing a Moving Ensemble (MWE) with Product of Correlation (PoC) processing scheme, measurement accuracy, reliability, and robustness can be obtained for measurement in left ventricular filling assessment. / Master of Science

La dégénérescence valvulaire mitrale (MVD) est la cardiopathie la plus fréquente chez le chien de petit format. Certaines variables écho-Doppler et sanguines sont incontournables dans son évaluation mais nécessitent d'être interprétées selon un intervalle de référence (IR) spécifique. L'objectif de ce travail a été de déterminer des IR pour 31 variables d'utilité clinique en cardiologie vétérinaire dans une population importante de chiens sains de petit format et selon les recommandations du Clinical and Laboratory Standard Institute. Les trois études réalisées permettent de conclure que l'élaboration d'IR spécifiques dans une sous-population canine est pertinente pour certaines variables. De plus, l'effet de certains facteurs comme le poids, l'âge et le sexe doivent être pris en compte si un intérêt clinique est identifié. / Degenerative mitral valve disease is the most common heart disease in small size dogs. Several echocardiographic, Doppler and blood variables are crucial in the assessment of the disease but need to be interpreted in the light of a specific reference interval (RI). The aim of this work was to determine RI for 31 variables of clinical interest in veterinary cardiology within a large population of healthy small size dogs by using the Clinical and Laboratory Standard Institute recommendations. The three studies performed here allowed to conclude that determination of specific RI in this canine sub-population is relevant. Moreover, the effect of covariates such as body-weight, age and gender should be taken into account only if a clinical interest is identified.

Syftet med studien var att jämföra hur väl transthorakal (TTE) och transesofageal ekokardiografi (TEE) kompletterar varandra vid diagnosticering av Staphylococcus Aureus (S. aureus) -endokardit (SAE). S. aureus är en av de ledande bakterierna inom vårdrelaterade infektioner. SAE blir vanligare, något forskare relaterar till att fler invasiva ingrepp görs. TTE är förstahandsalternativet för att besvara alternativt dementera frågeställningen och följs ofta av en TEE som bidrar till förbättrad bildkvalité och möjlighet att visualisera mindre strukturer. På Skaraborgs sjukhus i Skövde (SkaS) anses TEE-undersökningarna många gånger genomförs i onödan då få endokarditer hittas. Studien var jämförande med en kvantitativ ansats. Materialet har samlats in på kliniskt fysiologiskt laboratorium i Skövde. Det resulterade i elva deltagare. Båda könen inkluderades, patienter under 18 år exkluderades. Resultatet visade att fyra endokarditer diagnostiserades. Streptococcus Sanguinus var den bakterie som orsakade flest endokarditer medan S. aureus inte orsakade någon endokardit. Fem av elva patienter hade någon form av riskfaktor för endokardit. Fem av elva patienter blododlades positivt för S. aureus. Hygienen vid undersökningstillfällena, framförallt TEE är viktig då 80 % av vårdpersonalen kan vara bärare av S. aureus. TTE- och TEE-undersökningen kompletterar varandra. Kombinationen av undersökningarna gör resultatet tillförlitligt. TEE är därför av värde vid endokarditfrågeställning. / The purpose was to compare how transthoracic (TTE) and transesophageal echocardiography (TEE) complement each other in the diagnosis of Staphylococcus Aureus (S. aureus)-Endocarditis (SAE). S. aureus is one of the leading bacteria in health-related infections. SAE becomes more common, which researchers associate with more invasive interventions. TTE is a first step to confirm or rule out endocarditis and often followed by TEE-examination. At Skaraborg Hospital in Skövde (SkaS), the TEE-survey is considered unnecessary many times when not finding enough endocarditis. The study was a comparative study with quantitative approach, where the material was collected at clinical physiological laboratory at SkaS, Skövde, which resulted in eleven participants. Both sexes were included, patients below 18 years were excluded. Results showed that four endocarditis was diagnosed. Streptococcus Sanguinus was the bacterium that caused most endocarditis while S. aureus did not cause endocarditis. Five of eleven patients had some form of risk factor for endocarditis. Five of eleven patients were positive for S. aureus. Hygiene at the examinations, especially TEE is important because 80 % of healthcare professionals could be carriers of S. aureus. The TTE and TEE survey complement each other. Carrying out the surveys together is what makes the diagnosis safe.

Les maladies cardiovasculaires sont parmi les principales causes de mortalité à l’échelle mondiale. Un certain nombre de maladies cardiaques peuvent être identifiées et localisées par l’analyse du mouvement et de la déformation cardiaques à partir de l’imagerie médicale. Cependant, l’utilisation de ces techniques en routine clinique est freinée par le manque d’outils de quantification efficaces et fiables. Dans cette thèse, nous introduisons un algorithme de quantification appliqué aux images IRM marquées. Nous présentons ensuite un pipeline de simulation qui génère des séquences cardiaques synthétiques (US et IRM). Les principales contributions sont décrites ci-dessous. Tout d’abord, nous avons proposé une nouvelle extension 3D de la méthode de la phase harmonique. Le suivi de flux optique en utilisant la phase a été combiné avec un modèle de régularisation anatomique afin d’estimer les mouvements cardiaques à partir des images IRM marquées. En particulier, des efforts ont été faits pour assurer une estimation précise de la déformation radiale en imposant l’incompressibilité du myocarde. L’algorithme (dénommé HarpAR) a ensuite été évalué sur des volontaires sains et des patients ayant différents niveaux d’ischémie. HarpAR a obtenu la précision de suivi comparable à quatre autres algorithmes de l’état de l’art. Sur les données cliniques, la dispersion des déformations est corrélée avec le degré de fibroses. De plus, les segments ischémiques sont distingués des segments sains en analysant les courbes de déformation. Deuxièmement, nous avons proposé un nouveau pipeline de simulation pour générer des séquences synthétiques US et IRM pour le même patient virtuel. Les séquences réelles, un modèle électromécanique (E/M) et les simulateurs physiques sont combinés dans un cadre unifié pour générer des images synthétiques. Au total, nous avons simulé 18 patients virtuels, chacun avec des séquences synthétiques IRM cine, IRM marquée et US 3D. Les images synthétiques ont été évaluées qualitativement et quantitativement. Elles ont des textures d’images réalistes qui sont similaires aux acquisitions réelles. De plus, nous avons également évalué les propriétés mécaniques des simulations. Les valeurs de la fraction d’éjection et de la déformation locale sont cohérentes avec les valeurs de référence publiées dans la littérature. Enfin, nous avons montré une étude préliminaire de benchmarking en utilisant les images synthétiques. L'algorithme générique gHarpAR a été comparé avec un autre algorithme générique SparseDemons en termes de précision sur le mouvement et la déformation. Les résultats montrent que SparseDemons surclasse gHarpAR en IRM cine et US. En IRM marquée, les deux méthodes ont obtenu des précisions similaires sur le mouvement et deux composants de déformations (circonférentielle et longitudinale). Toutefois, gHarpAR estime la déformation radiale de manière plus précise, grâce à la contrainte d’incompressibilité du myocarde. / Cardiovascular disease is one of the major causes of death worldwide. A number of heart diseases can be diagnosed through the analysis of cardiac images after quantifying shape and function. However, the application of these deformation quantification algorithms in clinical routine is somewhat held back by the lack of a solid validation. In this thesis, we mainly introduce a fast 3D tagged MR quantification algorithm, as well as a novel pipeline for generating synthetic cardiac US and MR image sequences for validation purposes. The main contributions are described below. First, we proposed a novel 3D extension of the well-known harmonic phase tracking method. The point-wise phase-based optical flow tracking was combined with an anatomical regularization model in order to estimate anatomically coherent myocardial motions. In particular, special efforts were made to ensure a reasonable radial strain estimation by enforcing myocardial incompressibility through the divergence theorem. The proposed HarpAR algorithm was evaluated on both healthy volunteers and patients having different levels of ischemia. On volunteer data, the tracking accuracy was found to be as accurate as the best candidates of a recent benchmark. On patient data, strain dispersion was shown to correlate with the extent of transmural fibrosis. Besides, the ischemic segments were distinguished from healthy ones from the strain curves. Second, we proposed a simulation pipeline for generating realistic synthetic cardiac US, cine and tagged MR sequences from the same virtual subject. Template sequences, a state-of-the-art electro-mechanical (E/M) model and physical simulators were combined in a unified framework for generating image data. In total, we simulated 18 virtual patients (3 healthy, 3 dyssynchrony and 12 ischemia), each with synthetic sequences of 3D cine MR, US and tagged MR. The synthetic images were assessed both qualitatively and quantitatively. They showed realistic image textures similar to real acquisitions. Besides, both the ejection fraction and regional strain values are in agreement with reference values published in the literature. Finally, we showed a preliminary benchmarking study using the synthetic database. We performed a comparison between gHarpAR and another tracking algorithm SparseDemons using the virtual patients. The results showed that SparseDemons outperformed gHarpAR in processing cine MR and US images. Regarding tagged MR, both methods obtained similar accuracies on motion and two strain components (circumferential and longitudinal). However, gHarpAR quantified radial strains more accurately, thanks to the myocardial incompressibility constraint. We conclude that motion quantification solutions can be improved by designing them according to the image characteristics of the modality and that a solid evaluation framework can be a key asset in comparing different algorithmic options.

Les interactions entre coeur défaillant et organes périphériques sont centrales pour la compréhension de la variabilité de la présentation clinique, de la progression et du pronostic du syndrome insuffisance cardiaque. La congestion veineuse est considérée comme un des éléments les plus importants qui sous-tendent les interactions cardio-rénales et cardio-intestinales, faisant du retour à l’euvolémie un objectif majeur de la prise en charge du patient décompensé. De fait, la caractérisation non invasive du statut volémique permettrait d’optimiser la prise en charge en facilitant l’adaptation du traitement déplétif au cas par cas. L’objectif de ce travail est d’explorer l’effet délétère de la congestion veineuse chez le patient insuffisant cardiaque, en particulier en termes de dysfonction des organes cibles, et de répertorier l’intérêt de l’échographie multi-site pour la caractérisation du statut volémique dans cette population. / Venous congestion has been shown to play a major role in worsening renal function in acute decompensated heart failure, and recent data have challenged the assumption that end-organ dysfunction was driven by other hemodynamic alterations in patients with heart failure. Decongestion is thus considered as a major therapeutic goal in the management of patients with acute heart failure. As such, real-time assessment of patient’s fluid status may allow for a better management of patients with heart failure, enabling for a personalized management. The aim of this work is to explore the deleterious effect of venous congestion in patient with heart failure, particularly in terms of end-organ dysfunction. We also aimed to characterize the role of extra cardiac ultrasound for the assessment of the volume status in patients with heart failure.