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University of Macau / Faculty of Science and Technology / Department of Electrical and Computer Engineering

University of Macau / Faculty of Science and Technology / Department of Electrical and Computer Engineering

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Though several clinical monitoring ways exist and have been applied to detect cardiac atril fibrillation (A-Fib) and other arrhythmia, these medical interventions and the ensuing clinical treatments are after the fact and costly. Current portable healthcare monitoring systems come in the form of Ambulatory Event Monitors. They are small, battery-operated electrocardiograph devices used to record the heart's rhythm and activity. However, they are not energy-aware ; they are not personalized ; they require long battery life, and ultimately fall short on delivering real-time continuous detection of arrhythmia and specifically progressive development of cardiac A-Fib. The focus of this dissertation is the design of a class of adaptive and efficient energy-aware real-time detection models for monitoring, early real-time detection and reporting of progressive development of cardiac A-Fib.... The design promises to have a greater positive public health impact from predicting A-Fib and providing a viable approach to meeting the energy needs of current and future real-time monitoring, detecting and reporting required in wearable computing healthcare applications that are constrained by scarce energy resources. / by Redjem Bouhenguel. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

A cohort of 87 SLE female patients underwent non-invasive assessments (e.g., vascular ultrasound, pulse wave analysis with applanation tonometry and echocardiography with TDI). In addition, disease activity, organ damage and SLE-related lab markers were also evaluated. Forty female healthy subjects were included as normal control. / In summary, pulse wave analysis and tissue Doppler imaging are sensitive and accurate to detect premature atherosclerosis and subclinical myocardial dysfunction. The current study demonstrated a close correlation of inflammatory burden (disease activity and organ damage) to premature atherosclerosis and subclinical myocardial dysfunction, which may implicate the importance of routinely monitoring and early treatment to attenuate cardiovascular involvement. / Systemic lupus erythematosus (SLE), an autoimmune-inflammatory disease, results in multi-organ damage of the body. Compared to Caucasian, Chinese in Hong Kong have high prevalence of SLE. Cardiovascular diseases are common manifestations of SLE, which have emerged to be one of main causes of mortality. Detection of premature atherosclerosis, arterial stiffening and subclinical myocardial impairment early in the course of the disease is important as there may be a role of early therapeutic intervention in these patients that might translate into better clinical outcomes. In this regard, newer non-invasive methods, such as, pulse wave analysis and tissue Doppler imaging (TDI), have gained clinical popularity due to their accurate, reliable and reproducible measurements for the early detection of subclinical cardiovascular complications. / The main findings were as follows: (1) Increased arterial stiffness and premature atherosclerosis were demonstrated in SLE patients with mild disease and a low prevalence of end-organ damage and SLE itself was an independent risk factor of early atherosclerosis; (2) The abnormal vascular parameters correlated with disease activity; (3) SLE patients without overt cardiovascular involvement still have abnormal diastolic function with or without elevated LV filling pressure identified by a ratio of mitral Doppler inflow velocity to lateral annulus velocity (lateral E/E'>10) on pulse-wave and tissue Doppler echocardiography; (4) Both pulmonary artery hypertension and organ-damage were the independent predictors of elevated LV filling pressure alter adjustment of traditional risk factors, with the former adding incremental predictive value to the latter; (5) There was evidence of subclinical LV systolic dysfunction in patients with SLE even when LV ejection fraction appeared to be normal; (6) The independent determinants of subclinical LV systolic dysfunction included long disease duration of >10 years, active disease, reduced total arterial compliance as well as abnormal mid-wall fractional shortening, and the assessment of these factors provided incremental predictive value. / This thesis applied the above non-invasive methods to SLE subjects with the following aims: (1) To ascertain whether there is evidence of preclinical atherosclerosis (as indicated by carotid intima-media thickness), and/or increased arterial stiffeness (as reflected by direct and indirect surrogate parameters, including pulse wave velocity, augmentation index and ankle-brachial index) in SLE; (2) To investigate the relationships of these noninvasive vascular parameters to inflammatory disease burden in terms of SLE disease activity and organ damage; (3) To assess whether there is evidence of subclinical myocardial diastolic dysfunction; (4) To determine the associations between various clinical and echocardiographic parameters, including presence of pulmonary arterial hypertension, SLE-related clinical data, and elevated LV filling pressure; (5) To detect whether there is evidence of subclinical myocardial systolic dysfunction by tissue Doppler echocardiography; (6) To determine various clinical and echocardiographic parameters in predicting subclinical LV longitudinal-axis systolic function. / Shang, Qing. / Advisers: Yu Cheuk-man; Tam Lai-Shan; Yip Wai-Kwok. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3421. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 166-201). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Cardiovascular disease (CVD) affects millions of people and is a leading cause of death worldwide. CVD consists of a broad set of conditions including structural heart disease, coronary artery disease and stroke. Risk for each of these conditions accumulates over long periods of time depending on several risk factors. In order to reduce morbidity and mortality due to CVD, preventative treatments administered prior to first CVD event are critical. According to clinical guidelines, such treatments should be guided by an individual’s total risk within a window of time. A related objective is secondary prevention, or early detection, wherein the aim is to identify and mitigate the impact of a disease that has already taken effect. With the widespread adoption of electronic health records (EHRs), there is tremendous opportunity to build better methods for risk assessment and early detection. However, existing methods which use EHRs are limited in several ways: (1) they do not leverage the full longitudinal history of patients, (2) they use a limited feature set or specific data modalities, and (3) they are rarely validated in broader populations and across different institutions. In this dissertation, I address each of these limitations. In Aim 1, I explore the challenge of handling longitudinal, irregularly sampled clinical data, proposing discriminative and generative approaches to model this data. In Aim 2, I develop a multimodal approach for the early detection of structural heart disease. Finally, in Aim 3, I study how different feature inclusion choices affect the transportability of deep risk assessment models of coronary artery disease across institutions. Collectively, this dissertation contributes important insights towards building better approaches for risk assessment and early detection of CVD using EHR data and systematically assessing their transportability across institutions and populations.

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Atherosclerosis is a major contributor to cardiovascular disease and accounts for an estimated one third of deaths overall. In order to address the hemodynamic components of disease pathogenesis, researchers have focused on mechanotransduction of flow-dependent shear stress in the vascular endothelium as a source of novel pathological mechanisms. Understanding how unidirectional, laminar blood flow protects vessels from atherogenesis, while disturbed, oscillatory blood flow promotes it, stands to provide enormous insight into disease pathogenesis and may provide powerful, specific new therapies for cardiovascular disease intervention. The overall objective of this dissertation was to determine which microRNAs (miRNAs) and mRNAs are regulated by different flow conditions in vascular endothelial cells in vitro and in mouse carotid artery endothelium in vivo, and to identify which miRNAs mediate flow-dependent vascular inflammation. The overall hypothesis of this project was that oscillatory shear (OS) and laminar shear (LS) stress differentially alter the expression of mechanosensitive miRNAs each capable of regulating complex networks of gene expression, which in turn leads to inflammation in endothelial cells. This hypothesis was tested using both in vitro and in vivo approaches, high throughput microarray analyses, and functional validation of specific targets by PCR. The findings from the partial carotid ligation model show that acute exposure to disturbed flow results in accelerated endothelial dysfunction and atherosclerosis in vivo. High-throughput microarrays reveal distinct expression profiles of both miRNAs and mRNAs in mouse endothelium exposed to disturbed flow suggesting the regulatory mechanisms by which miRNAs regulate mRNAs resulting in EC inflammation, the earliest stage of atherosclerosis. This in vivo study provides new insight into the mechanisms of flow induced atherosclerosis. In particular, the upregulation of miR-663 due to OS in HUVEC causes monocyte adhesion, but not endothelial apoptosis, in an ICAM-1 dependent manner. miR-663 regulates a group of genes including transcriptional factors and inflammatory genes which may also mediate OS-induced EC inflammation. Collectively, revealing the profiles of miRNAs and mRNAs regulated by hemodynamic flow provides a better understanding in vascular diseases and provide potential target for developing effective preventative therapeutic approaches in cardiovascular diseases.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / This thesis is concerned with the testing of an “auscultation jacket” as a means of recording heart sounds and electrocardiography (ECG) data from patients. A classification system based on Neural Networks, that is able to discriminate between normal and abnormal heart sounds and murmurs, has also been developed . The classification system uses the recorded data as training and testing data. This classification system is proposed to serve as an aid to physicians in diagnosing patients with cardiac abnormalities. Seventeen normal participants and 14 participants that suffer from valve-related heart disease have been recorded with the jacket. The “auscultation jacket” shows great promise as a wearable health monitoring aid for application in rural areas and in the telemedicine industry. The Neural Network classification system is able to differentiate between normal and abnormal heart sounds with a sensitivity of 85.7% and a specificity of 94.1%.