No description available.

Thesis (Ph.D.)--University of Western Australia, 2006.

Bibliography: leaves 306-353. / xiii, 353 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Utilizing a paired transcoronary sampling technique, serial determination of myocardial drug content was determined following intravenous bolus injection in patients undergoing diagnostic cardiac catheterization for the investigation of chest pain. There was significant modulation of haemodynamic effects of all three drugs according to changes in systolic interval. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, Queen Elizabeth Hospital, Cardiology Unit

published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Medical Sciences

No description available.

[Truncated abstract] This thesis concerns itself primarily with the impact of exercise training on cardiac and vascular adaptations in humans. It contains longitudinal studies of individuals at either end of the physical activity spectrum; young elite athletes and obese children and adolescents. The study of these diverse groups was intentional, as a particular interest was to investigate the possible inter-relationships between morphological adaptations in the heart, evident in both obese and athletic populations, and the possible consequences of such adaptations for cardiac function. Whilst there exists a long tradition of echocardiographic assessment of cardiac dimensions and mass in both athletic and clinical populations, investigation of the impact of each of these “conditions” on cardiac diastolic function is novel, and has been facilitated by recent advances in the technical approach to diastolic function assessment in humans. Studies presented in the following chapters utilise advanced echocardiography imaging combined with pulse wave and tissue Doppler approaches to investigate the effects of exercise training regimen on wall thickness and ventricular mass, as well as diastolic function indices. State-of-the-art vascular imaging approaches have also been used in these populations to determine whether changes in vascular wall thickness, diameter or function occur with training in the elite athletes or obese youth.

Thesis (Ph.D.)--Biomedical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Oshinski, John N.; Committee Member: Fyfe, Derek A.; Committee Member: León, Angel R.; Committee Member: Skrinjar, Oskar; Committee Member: Taylor, W. Robert.

Thesis (M. Tech.) -- Central University of Technology, Free State, 2010 / This main aim of this study was to assess patients in a general cardiology practice in order to determine the systolic and diastolic profiles of these patients. The aim was also to determine what effect life style and risk factors may have on the echocardiographic variables measured during such an examination. The specific aim of this study was the importance of not only examining the systolic function but the necessity to also examine the diastolic profile of patients. Life-style plays an important role, with the main culprit being obesity. Obesity was the single most important factor that affected the diastolic profile of patients seen in this study. With obesity a combination of other risk factors related to obesity was observed. Most abnormalities found due to these risk factors were associated with diastolic changes in the left ventricle. Echocardiography is routinely used in daily practice, but the diagnostic value of this tool can be enhanced if proper analyses of the systolic as well as the diastolic profiles are determined. Many cardiologists only measure the systolic function of the heart as an indication of the well- being of the left ventricle, although in this study it was proven that systolic function did not alter with ageing or with changes in the risk profile. Hundred-and-twelve patients, divided into three age groups, were evaluated in this study. Both systolic and diastolic variables were measured and analysed for abnormalities. None of these patients had systolic function abnormalities, although they had detectable anatomic changes due to ageing, obesity and hypertension. Several abnormalities were found on the diastolic profile of these patients. Muscle thickness increased due to obesity and hypertension and even with ageing, but with no significant abnormalities in the systolic function of the heart. There was a slight increase in the circumferential shortening of the left ventricle and that both the septal and longitudinal functions decreased with ageing. It is noteworthy that even where the systolic function remained normal in ageing subjects, their diastolic profiles changed significantly. Assessment of left ventricular function required a meticulous and systematic approach. In this study forty- one percent of patients visiting this general practice had abnormalities of their diastolic function although their systolic function was normal. It was found that with ageing, especially in the older age group, important abnormalities occur in their diastolic profile. The most common changes were that the E- peak velocity decreased and that the Apeak velocity of the trans-mitral flow increased. It seemed that passive filling decreased with ageing but that active filling increased simultaneously, causing the cardiac output to remain constant in older subjects. This is important to know because diseases affecting the atrium may have a profound effect on the cardiac output of older patients, even if they have normal systolic function, (due to the decreased passive filling they need their active filling or atrial contraction to support a normal cardiac output). An important marker will be to look at the ratio of the E/A- velocities in older patients to determine the ratio of active against passive filling. Other than that, a relatively new tool in echocardiography called tissue Doppler was used to determine what happened to the muscle with ageing. Here it was demonstrated that the different layers of the left ventricle acted differently with ageing. Results showed that the longitudinal fibres weakened with ageing although the circumferential fibres remained unchanged or even strengthened with ageing. It was apparent in this study that the traditional use of only systolic function may not be adequate when evaluating relative asymptomatic patients presenting at a general cardiology practice. It is important to also evaluate the diastolic profiles of these patients in order to scientifically quantify their heart health, even in asymptomatic patients. It is important to routinely evaluate the diastolic profile of patients so that early detection of these diastolic variables can be detected and timely consideration for its treatment can be given by their cardiologist. It is also important to take note of the significance of the obesity problem and the effect it has on the heart’s health. In conclusion, this study emphasizes the importance of the echocardiographic evaluation of diastolic cardiac function in addition to routine systolic evaluation in asymptomatic patients. This will enable the clinician to detect abnormalities early and tailor therapy accordingly. Lifestyle related risk factors, especially obesity, also have significant effects on diastolic cardiac function.

Synchronous contraction and relaxation of the myocardium is required to optimize cardiac function. Regional timing of contraction and relaxation is dyssynchronous in many patients with heart failure. Cardiac resynchronization therapy (CRT) is a highly successful treatment for dyssynchronous heart failure. Patients are currently selected for CRT using surface electrocardiogram QRS duration as a measure of dyssynchrony. However, up to 30% of patients selected for CRT show no improvement. This poor response rate may in part be explained by the poor correlation between mechanical dyssynchrony and QRS duration. Thus, better methods to quantify mechanical dyssynchrony in the heart may improve the poor CRT response rate. The overall goal of this project was to develop better methods to diagnose dyssynchrony in the left ventricle (LV). We developed two new methods with different approaches. The first method improved upon existing tissue-Doppler based echocardiographic diagnosis of dyssynchrony by utilizing a cross-correlation (XC) function to quantify dyssynchrony during post-processing as opposed to the quantitatively simplistic time-to-peak analysis that is currently utilized. The second method utilized standard cine cardiac magnetic resonance (CMR) images to quantify the dyssynchrony in the flow of blood within the LV, which may represent a more direct, physiologically relevant measure of dyssynchrony. Specific aim 1 demonstrated that the new XC delay parameters can be quantified accurately with a stationary region of interest and therefore require significantly less post-processing time to calculate compared to the time-to-peak dyssynchrony parameters. Specific aim 2 showed that XC delays are superior to existing time-to-peak dyssynchrony parameters at discriminating patients with LV dyssynchrony from those with normal function. The time-to-peak parameters showed dyssynchrony in approximately half of the normal, healthy volunteers while the XC delay parameters had nearly perfect diagnostic accuracy. The results of specific aim 3 showed that XC delays could diagnose acute, pacing-induced dyssynchrony in young, healthy children with 79% accuracy while the time-to-peak parameters showed accuracies of 71%, 57% and 57%. Specific aim 4 showed that CMR-based quantification of LV internal flow can be used to discriminate patients with dyssynchronous heart failure from normal controls with 95% accuracy.