Dissertation submitted to the Faculty of Health Sciences of the University of the Witwatersrand, Johannesburg in fulfilment of the requirement for the degree of Master of Science in Medicine. Johannesburg 23 April 2015 / Knowledge of the anatomical variation in the carotid arterial system is important in understanding the pathogenesis and surgical treatment of atheroma. Thus, this study investigated the anatomical variation of the carotid arterial system and the frequency of atheroma within a South African population. The carotid arterial systems were exposed bilaterally in 77 adult cadavers using standard dissection. The level of the carotid bifurcation, position and curving of the carotid arteries and frequency of common trunks and atheroma were recorded. In addition, the lengths and diameters of the carotid arteries and branches as well as the bifurcation angle were measured. Data was analyzed using descriptive and inferential statistics. The carotid bifurcation most commonly occurred at the C3-C4 intervertebral disc. White males had longer common carotid arteries than white females. The lengths of the internal and external carotid arteries were longer in white males compared to black males. There was a higher frequency of curving of the carotid arteries in white females compared to white males. The thyro-lingual trunk was the most common trunk within the sample. The internal carotid artery was postero-lateral to the external carotid artery within most individuals. In addition, atheroma was observed at the carotid bifurcation in all individuals. The level of the carotid bifurcation, positioning, length and diameter of the carotid arteries in the South African population are similar to descriptions in anatomical texts. The differences found within the study may be attributable to the age of the sample as well as the embryological development of the carotid arteries within the South African population. These variations may influence blood flow within the carotid arteries. Thus, knowledge of these variations may aid in understanding the aetiology and the surgical treatment of atheroma.

Thesis (Ph. D.)--University of Washington, 1996. / Includes bibliographical references (leaves [97]-104).

No description available.

Diss. (sammanfattning) Örebro : Örebro universitet, 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 132-143).

Abstract Different metabolic and environmental factors affect the blood pressure level, constituting a cluster, especially in hypertensives, that leads to an increased risk of cardiovascular diseases. The present research was designed to determine the prevalence and the predictors of the metabolic syndrome and the role of insulin and blood pressure in carotid atherosclerosis in 600 treated male and female hypertensives aged 40-59 years and 600 age- and sex-matched controls. The prevalence of the metabolic syndrome in different population-based cohorts varied, depending on the definition, from 0.8% to 35.3%, being lowest in control men and women and highest in hypertensive men. 73.8% of a random, middle-aged, urban population showed at least one cardiovascular risk factor, and 91.3% of all hypertensive subjects showed at least one cardiovascular risk factor in addition to hypertension itself. The independent predictors of the metabolic syndrome were waist circumference, uric acid, total cholesterol and gamma-glutamyl transpeptidase. Hypertension had a significant effect on carotid intima-media thickness and the prevalence of plaques in men, but its effect in women was not significant. A long duration of hypertension resulted in greater intima-media thickness and a higher prevalence of plaques, particularly in men. There were significant associations between gamma-glutamyl transpeptidase and the components of the metabolic syndrome after adjustment for alcohol consumption and also in teetotallers. There were inconsistent associations between the different insulin measures and the intima-media thickness as a measure of carotid atherosclerosis. The exclusion of diabetic subjects did not change the results. In conclusion, a cluster of metabolic abnormalities related to hypertension is frequent among both controls and treated hypertensive subjects. Hypertensive subjects have higher prevalences of carbohydrate and lipoprotein aberrations and structural and functional cardiovascular complications than age- and sex-matched controls.

published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

Carotid artery wall stiffness has been widely considered as an index of vascular health, and has been associated with occurrence of cardiovascular events, such as stroke. In addition, the blood flow patterns in the carotid artery can yield crucial information on atherosclerosis progression and cerebrovascular impairment. Pulse wave imaging (PWI) is a non-invasive ultrasound imaging technique that tracks the propagation of the arterial pulse wave, providing thus regional arterial wall stiffness mapping. Moreover, towards enabling accurate visualization of blood flow patterns, ultrasound-based vector flow imaging (VFI) modalities have been developed. Building upon PWI and VFI techniques, the overall goal of this dissertation is to develop ultrasound-based methodologies that can provide simultaneous imaging of the carotid artery wall mechanics and blood flow dynamics at high temporal and spatial resolutions. The developed techniques are validated through vessel phantom experiments and simulations. Furthermore, their potential to diagnose pre-clinical stages of carotid artery disease and provide additional insights in risk for stroke assessment, is demonstrated in an atherosclerotic swine study and human subjects in vivo. More specifically: A method is presented that analyzes the pattern of arterial wall motion derived by PWI, in order to detect spatial mechanical inhomogeneity across an imaged artery, and provide piecewise arterial wall stiffness estimates. The proposed technique is validated in a phantom consisting of a soft and a stiff segment, while its feasibility is demonstrated to identify inhomogeneous wall properties in atherosclerotic human carotid arteries, as well as provide atherosclerotic plaque mechanical characterization in vivo. Subsequently, PWI is integrated with VFI techniques in the same ultrasound acquisition sequence, in order to enable simultaneous and co-localized imaging of arterial wall stiffness and blood vector flow velocity. The performance of the technique is investigated through experiments and FSI simulations. Moreover, its feasibility was shown to investigate associations between carotid artery Pulse Wave Velocity and blood flow patterns, in vivo. Based on the previously developed PWI and VFI modalities, a novel ultrasound-based technique is developed that combines high frame rate vector flow imaging with a data clustering approach, in order to enable direct and robust wall shear stress measurements. The performance of the proposed method is evaluated through vessel phantom experiments and simulations, while its feasibility is shown to detect pre-clinical stages of carotid artery disease in a swine model in vivo. In addition, a pilot clinical study is presented involving application of the developed modality in normal and atherosclerotic human carotid arteries in-vivo. Moving forward, the developed imaging modalities are used to implement novel clinical biomarkers based on carotid artery arterial wall mechanics and blood flow dynamics, that can potentially assist in risk for stroke assessment. The patterns of those biomarkers are investigated in the common carotid arteries of subjects with low degree of stenosis and medical history of stroke, against subjects without history of stroke. The same biomarkers are also analyzed with respect to stroke symptomatology in atherosclerotic patients with moderate to high degree of stenosis. Moreover, the developed techniques are used to identify vulnerable plaque components in subjects with fully developed plaques, as compared with CTA scans. Finally, a deep learning-based approach for motion tracking of the arterial wall throughout the cardiac cycle is proposed. A neural network is trained to learn the motion patterns of the carotid artery and potentially improve the quality of PWI. The performance of the technique is assessed in vessel phantom experiments and its feasibility is demonstrated in healthy human carotid arteries in-vivo.

Brain stroke is considered as one of the three diseases that threaten human health all over the world. Hypertension and cerebral arteriosclerosis are thought to be the most dangerous risk factors of brain stroke, and they frequently occur together, leading to ischemia of brain tissue. Unfortunately, it is not clear whether the pathological changes resulting from hypertension are related to those resulting from cerebral arteriosclerosis. There have been no ideal animal models mimicking the pathological changes in such a combined condition. In this thesis, an animal model of hypertension combined with cerebral arteriosclerosis in rats was established by occlusion of both the left and right common carotid arteries in spontaneous hypertension rats. Pien Tze Huang (PTH), a reputed traditional Chinese medicinal complex, contains Radix notoginseng, snake bile, calculus bovis, and musk and some other components that are known to protect vessels and cells from injuries. Since different tissue injuries share many common cellular mechanisms, the protection by PTH to in nerves and the circulation systems may also be benefical to cerebrovascular conditions as well. In present experiments, PTH was used to treat hypertension rats that also developed chronic brain ischemia as a result of the bilateral carotid occlusion, and its protective role for neurons and blood vessels was investiaged. / From the data above, more severe damage could be caused by hypertension combined with chronic ischemia. The model of SHR with bilaterally occluded common carotid artery can be used to study pathological changes resulted from hypertension combined with chronic ischemia. PTH was able to protect neurons in stroke. / In the initial part of the work, patients from clinics in two cities in South and North China were compared and analysed; they had been suffering from brain ischemic stroke. About two thirds of the stroke patients were found to have hypertension before the onset of stroke. Their prognosis was significantly worse than those stroke patients without hypertension. In the hypertensive rats with occluded arteries, mean of functional magnetic resonance imaging (fMRI) examination showed that brain blood flow was very weak or even transiently became undetectable at the beginning of the acute stage of brain ischemia, but was restored one hour after the occlusion surgery. In addition, pathological changes in brains of hypertensive rats with induced brain ischemia (carotid occlusion) were examined by Nissl staining, TUNEL staining, cell death ELISA and anti-oxidation enzymes. At day 15 after ischemia, a large number of pyramid cells in the hippocampus of SHR were lost and a great deal of apoptotic cells were found in the CA1 of the hippocampus, while activities of some enzyme including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were increased. At day 30 and 60, some degenerative changes appeared to have subsided and the cells appeared morphologically normal. The activities of the above enzymes were also decreased at day 60. In WKY control rats with normal blood pressure, neurons in the CA1 were found less damaged after the bilateral carotid occlusion. It was found that apoptotic and dead cells were significantly reduced in rats with hypertension combined with chronic brain ischemia if they had been pre-treated with PTH. Moreover, brain stroke damage was less severe in this pretreated rats. / Zhang, Lihong. / "March 2010." / Adviser: WH Kwong. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 116-134). / 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 Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy