Background: Cardiovascular health disparities across subpopulations and geographies have been well-documented in urban areas. Evidence suggests that racial minorities and low-socioeconomic groups have high risks of developing cardiovascular diseases (CVD). Residents of the Appalachia also exhibit high rates of CVD, but little is known about the relationships between cardiovascular risk factors, spatial disadvantage, and cardiovascular health outcomes in this region. Thus, this study aimed to examine the independent association between neighborhood factors and subclinical atherosclerosis in an asymptomatic population from central Appalachia. Methods: Community-dwelling asymptomatic individuals (n=210) were screened for Coronary Artery Calcium (CAC), a subclinical marker for coronary atherosclerosis, from January 2010 to January 2014. Based on the standard Agatston Scale, participants were grouped into 4 CAC scores: zero (CAC = 0), mild (CAC = 1-99), moderate (CAC = 100-399) and severe (CAC ≥ 400) to determine the severity of coronary artery disease (CAD). Demographic information (e.g., age, gender, race, and marital status), cardiovascular risk factors (e.g., hypertension, hypercholesterolemia, obesity, smoking, and family history of CAD), and neighborhood level characteristics (racial and socioeconomic characteristics of the population) were used in ordinal logistic regression analyses performed in Stata 14.1. Results: Of the 210 participants, over three-fourths (79%) had a CAC score greater than 1. While 67% of the participants were hypertensive, 80% had hypercholesterolemia, 75% were overweight or obese, 52% had a history of smoking, and 55% had a family history of CAD. There were significant differences in the socioeconomic environment of these residents. Specifically, zip-code median household income was higher for individuals with zero CAC score. Additionally, the zip-code household poverty percentage was higher for those with CAC scores ≥ 1. Although all the neighborhood factors increased the odds of having higher CAC score, none of them were statistically significant. Conclusion: The positive, albeit statistically non-significant, association of adverse neighborhood factors with higher CAC scores suggests the need for larger studies for further understanding of this association. Finally, achieving the Healthy People 2020 goal of reducing or eliminating disparities requires risk factor screening and control in high prevalent areas such as central Appalachia, and understanding the neighborhood level dynamics for CVD.

Background: Atherosclerosis is an important cause of stroke. Ultrasound offers the convenience of real-time and detailed assessment of carotid plaque features as well as arterial wall thickening and composition. Evaluation of these features is important for determining patients’ risk of suffering vascular events and also contributes to selecting the best treatment strategy. Methods: Using ultrasound data analysis we have determined plaque features in the bifurcation and internal carotid artery (ICA), including: surface plaque irregularities, calcification, echogenicity (grey scale median-GSM) and other textural plaque features (Juxtaluminal black area, entropy, coarseness). In addition, intima media thickens (IMT) and its grey scale median (IM-GSM) was measured in common carotid artery (CCA). Using Cone Beam CT (CBCT) we have quantified calcification volume of the carotid plaques extracted after carotid endarterectomy procedure. For the meta-analysis we have used comprehensive meta-analysis software version 3. Study I: We have included 39 patients and we compared carotid plaque features of the contralateral arteries with those located ipsilateral to symptomatic side and arteries of asymptomatic patients. Study II: The accuracy of US to detect atherosclerosis calcification was assessed against CBCT in 88 patients. Study III: Based on the previous vascular events in coronary, carotid and lower extremity arterial system, 87 patients were divided into three groups: asymptomatic, symptoms in one vascular system and symptoms in more that one vascular system. IMT, IM-GSM and plaque features were compared between groups. Study IV: We have meta-analyzed ten cohort prospective studies evaluating carotid plaque echogenicity for cerebrovascular symptoms prediction. Results: Study I. Plaques of the contralateral to symptomatic arteries had similar features to those in symptomatic and more vulnerable than asymptomatic arteries. Study II. Carotid ultrasound was accurate in detecting calcification volumes of ≥8mm3 with very high sensitivity but it was less accurate in detecting lower calcification volumes (<8mm3). Carotid calcification was not different between symptomatic and asymptomatic patients. Study III. Echogenicity of the intima-media complex (IM-GSM), but not its thickness (IMT), was significantly decreased with increasing number of arterial systems affected by atherosclerosis. IM-GSM was lower in patients with prior myocardial infarction and stroke. Study IV. Carotid plaque echogenicity evaluated by US could predict future cerebrovascular events in patients with asymptomatic, relative risk RR 2.72 (95% CI, 1.86 to 3.96), and recurrent symptoms in symptomatic patients, RR 2.97 (95% CI, 1.85-4.78). Conclusion: Plaques located in the contralateral to symptomatic arteries have similar features as symptomatic side and more vulnerable than asymptomatic arteries. Carotid ultrasound could accurately detect larger but not smaller carotid plaque calcification volumes (<8 mm3). Low IM- GSM could identify patients with multi-system atherosclerosis disease, suggesting a better marker for determining systemic atherosclerosis disease burden compared to conventional IMT. Finally, carotid plaque echogenicity predicts future cerebrovascular events in patients with symptomatic and asymptomatic carotid stenosis.

Motivation: Ischemic heart disease is the eighth leading cause of death in an African population. Silent ischemia can be defined as an ischemic episode without associated pain. The clinical significance of silent ischemia is growing and can now be considered as a risk factor in the development of coronary disease. Hypertension and associated risk factors, hypercholesterolemia and diabetes are associated with silent ischemia. Other factors such as higher pulse pressure, double product, heart rate and higher carotid intima-media thickness are also associated with silent ischemia. Urbanisation is rising in South-Africa. This new lifestyle is associated with several risk factors including: poor diets, lower physical activity levels, hypertension and increased smoking and alcohol abuse. The prevalence of stroke is high among Africans, which can be due to a higher prevalence of hypertension, diabetes and obesity. Purpose: The purpose of this study was to determine the associations between silent ischemia and cardiovascular function in African men. The focus fell on hypertension and associated risk factors, higher total cholesterol levels, and increased pulse pressure, heart rate and sub-clinical atherosclerosis. vi Methodology: This study constituted a population study in the North-West province carried out on urbanized African male teachers aged between 20-60 years. The SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) sub-study consisted of a total of 80 African male volunteers. The Cardiotens apparatus was placed on each participant on the first morning. This apparatus took ambulatory blood pressure measurements as well as Electrocardiogram measurements. Hereafter, participants continued with their normal work day until 1700. After an overnight stay at the Metabolic unit of the North-West University Potchefstroom campus, the apparatus was removed at 0600. During statistical analyses, the African males were divided into groups of participants with silent ischemia (SI) and those without silent ischemia (nSI), as determined by the ambulatory electrocardiogram. Statistical analyses were performed by means of the Statistica version 10 software program. Results: In comparison with the nSI men, the SI showed the following: above normal high sensitivity C-reactive protein and glucose, higher ambulatory blood pressure, heart rate, pulse pressure, resting ST-segment depression and carotid intima-media thickness. Multiple regression analyses indicated that ambulatory silent ischemia is associated with sub-clinical atherosclerosis, possibly increasing their stroke risk. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2012.

Motivation: Ischemic heart disease is the eighth leading cause of death in an African population. Silent ischemia can be defined as an ischemic episode without associated pain. The clinical significance of silent ischemia is growing and can now be considered as a risk factor in the development of coronary disease. Hypertension and associated risk factors, hypercholesterolemia and diabetes are associated with silent ischemia. Other factors such as higher pulse pressure, double product, heart rate and higher carotid intima-media thickness are also associated with silent ischemia. Urbanisation is rising in South-Africa. This new lifestyle is associated with several risk factors including: poor diets, lower physical activity levels, hypertension and increased smoking and alcohol abuse. The prevalence of stroke is high among Africans, which can be due to a higher prevalence of hypertension, diabetes and obesity. Purpose: The purpose of this study was to determine the associations between silent ischemia and cardiovascular function in African men. The focus fell on hypertension and associated risk factors, higher total cholesterol levels, and increased pulse pressure, heart rate and sub-clinical atherosclerosis. vi Methodology: This study constituted a population study in the North-West province carried out on urbanized African male teachers aged between 20-60 years. The SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) sub-study consisted of a total of 80 African male volunteers. The Cardiotens apparatus was placed on each participant on the first morning. This apparatus took ambulatory blood pressure measurements as well as Electrocardiogram measurements. Hereafter, participants continued with their normal work day until 1700. After an overnight stay at the Metabolic unit of the North-West University Potchefstroom campus, the apparatus was removed at 0600. During statistical analyses, the African males were divided into groups of participants with silent ischemia (SI) and those without silent ischemia (nSI), as determined by the ambulatory electrocardiogram. Statistical analyses were performed by means of the Statistica version 10 software program. Results: In comparison with the nSI men, the SI showed the following: above normal high sensitivity C-reactive protein and glucose, higher ambulatory blood pressure, heart rate, pulse pressure, resting ST-segment depression and carotid intima-media thickness. Multiple regression analyses indicated that ambulatory silent ischemia is associated with sub-clinical atherosclerosis, possibly increasing their stroke risk. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2012.

With the high mortality rate of cardiovascular disease, it is important to study the early signs. The early detection of cardiovascular disease can lead to saved lives. Currently the most prevalent detection methods are the Framingham Risk Score and the carotid intima media thickness, both of which are insufficient. The necessary tool for early detection requires a uniform quantification system. The stimulus leading to endothelial dysfunction, the most significant predictor of a major adverse cardiovascular event (MACE)—and subsequently subclinical atherosclerosis—is reduced shear stress. Increased surface relative roughness affects the flow profile transition from laminar to turbulent resulting in reduced shear rate. The relationship between the shear stress and the relative roughness was studied using a computer model for fluid flow. A model of the brachial artery was generated to study its hemodynamics. Roughness values for both laminar and turbulent flow were calculated to use with the governing equations programmed in COMSOL Multiphysics. With all other factors remaining constant in the model, the roughness values were changed. From the model profile plots, line graphs, and numeral data are generated. This data provides information about how the shear stress and the shear rate change with respect to the relative roughness value. The models with different wall boundary conditions—slip versus Navier slip—were unable to be directly compared due to the differences in value magnitude. When the flow profile transitions from laminar to turbulent, there is a corresponding drop in both the shear stress and the shear rate values. Additional testing is required to determine a critical relative roughness value for this change in cumulative shear.

Cardiovascular disease is the leading cause of death globally and is responsible for taking 17.9 million lives per year. Despite the use of clinical treatments and detection methods, there remains a large population of individuals that suffer from CVD whose symptoms are left undetected and untreated prior to a life-threatening cardiac event. This highlights a need for an early detection method that can prevent the manifestation and worsening of the disease as well as address limitations of current early detection methods. An area of interest for early detection of CVD is subclinical atherosclerosis, which is the long, early, asymptomatic stage of plaque formation. Subclinical atherosclerosis has been namely associated with endothelial dysfunction and is the result of the pathological state of the endothelium due to its impact on vascular homeostasis, thrombosis, and vascular tone. Endothelial dysfunction is a result of several factors contributing to and promoting inflammation and results in changes in biological pathways that can alter the surface of the endothelium. This surface modification or added roughness changes the flow profile from laminar to turbulent flow due to the decreased shear stress on the vascular wall. Current detection methods such as carotid intima media thickness (CIMT) and flow-mediated dilation (FMD) targeted at identifying the early stages of atherosclerosis present limitations such as identifying late-stage effects of plaque formation and subjective readings highlight the need for a different approach to early detection. This experimental study aims to present a possible method of detecting the morphological changes of the endothelium due to inflammation through acoustic analysis of flow. Three silicone artery phantom groups were created with different degrees of inner diameter surface roughness to explore the relationship between relative roughness and sound associated with fluid flow. The results of this study are power spectral density graphs (PSD) which show frequency peaks associated with each of the phantoms at a theoretical laminar and turbulent Reynolds number. The PSD graphs show that there is a difference in frequency response between a smooth and rough artery phantom at the same flow rate providing preliminary support that sound analysis of fluid flow could provide information regarding early-stage cardiovascular disease.

A study was performed on a recently developed prototype of the Yong-Geddes surrogate arm design to collect compliance data of the various system components and determine the accuracy of measurements made through the bench top model. The study was performed to perceive the effectiveness of the model as a tool for validating non-invasive blood pressure detection monitors. Three stages of testing were performed to gather pressure and volume data from an artificial artery component, a sphygmomanometer, and the surrogate arm system to produce compliance estimations. Mathematical equations from supported arterial hemodynamics studies and clinical trials were applied to the pressure and volume data. Dr. Drzewiecki’s equation for arterial compliance was capable of predicting the region of the highest compliance of the artificial artery and produced an overall value of 38.81% for the data. A second degree inverse polynomial was developed and modeled the sphygmomanometer compliance measurements with a of 99.09%. Significant error was observed throughout all stages of the compliance testing, which was attributed to factors such as excessive noise due to faulty data collection equipment and irreparable leaks in the fluid flow system.

INTRODUCTION: The risk factors for cardiovascular disease (CVD) are associated with coronary atherosclerosis and having multiple risk factors potentiates atherosclerosis. This study examined the prevalence of multiple biological and lifestyle/behavioral risk factors and their association with coronary artery calcium (CAC), a marker for subclinical coronary atherosclerosis. METHODS: This is a cross-sectional study of 1607 community-dwelling asymptomatic individuals from central Appalachia who participated in CAC screening between January 2011 and December 2012. Data on demographics (sex and age) and 7 traditional risk factors for coronary artery disease (CAD) were collected and categorized into 5 groups (0-1, 2, 3, 4, and ≥5). Prevalence of these risk factors and CAC scores (0, 1-99, 100-399, ≥400) were assessed, and the impact of the number of risk factors on CAC scores were delineated using multiple logistic regression. RESULTS: Over 98% of participants had ≥1 risk factor. While obesity, diabetes, hypertension, and family history of CAD significantly increased the odds of having CAC, CAC scores significantly increased with number of risk factors. After adjusting for demographic factors, having 3, 4, and ≥5 risk factors was significantly associated with increased odds of having higher CAC scores when compared to zero CAC score by more than one and half times [OR=1.65, CI (1.20-2.25)], two times [OR=2.32, CI (1.67-3.23)] and three times [OR=3.45, CI (2.42-4.92)], respectively. CONCLUSION: The high prevalence of multiple risk factors in the study population suggests the need for aggressive multiple risk factors interventions for primary prevention of CAD, which could address CVD health disparities.

Aim: To examine the association of cardiovascular disease risk factors with and their cumulative effect on coronary artery calcium in hard-to-reach asymptomatic patients with diabetes. Methods: : A total of 2563 community-dwelling asymptomatic subjects from Central Appalachia participated in coronary artery calcium screening at a heart centre. Binary variable was used to indicate that coronary artery calcium was either present or absent. Independent variables consisted of demographic and modifiable risk factors and medical conditions. Descriptive statistics and multinomial logistic regression analyses were conducted. Results: : In total, 55.8% and 13.7% of study participants had subclinical atherosclerosis (coronary artery calcium ⩾1) and diabetes, respectively. The presence of coronary artery calcium was higher in subjects with diabetes (68.5%) than those without (53.8%). Compared to subjects without diabetes with coronary artery calcium = 0, obesity, hypertension, hypercholesterolaemia and smoking increased the odds of the presence of coronary artery calcium (coronary artery calcium score ⩾1) regardless of diabetes status; however, with larger odds ratios in subjects with diabetes. Compared to subjects without diabetes with coronary artery calcium score = 0, having 3, 4 and ⩾5 risk factors increased the odds of presence of coronary artery calcium in subjects with diabetes by 14.06 (confidence interval = 3.26–62.69), 32.30 (confidence interval = 7.41–140.82) and 47.12 (confidence interval = 10.35–214.66) times, respectively. Conclusion: : There is a need for awareness about subclinical atherosclerosis in patients with diabetes and more research about coronary artery calcium in subpopulations of patients.

Background: Annually, over 150,000 cardiovascular events occur among individuals ,65 years old in the United States, including asymptomatic ones. Coronary artery calcium (CAC), a subclinical marker of coronary artery disease (CAD), enhances risk stratification among asymptomatic individuals. This study assessed the prevalence of CAC in a rural population and determined relationships between traditional risk factors for CAD and CAC scores. Methods: During January 2011 to December 2012, asymptomatic individuals from central Appalachia were screened for CAC in the largest tertiary cardiovascular institute. Based on Agatston scale, participants were grouped into 4 CAC scores: zero (CAC 5 0), mild (CAC 5 1-99), moderate (CAC 5 100-399) and severe (CAC $ 400). Multinomial logistic regression was used to examine associations between potential risk factors of CAD and CAC score. Results: Of 1,674 participants, 55.4% had positive CAC score (CAC . 0). Increasing age and being male were positively associated with higher CAC scores. Although there was significant association between mild CAC and hypertension and family history of CAD, moderate CAC was positively associated with smoking status. Except hypercholesterolemia and sedentary lifestyle, severe CAC was significantly associated with major health conditions (obesity, diabetes and hypertension), lifestyle (smoking) and family history of CAD. Conclusions: More than half of participants in the CAC screening had subclinical CAD (CAC score . 0). The association between CAC score and CAD risk factors suggests that education about subclinical atherosclerosis among asymptomatic individuals in this region with high cardiovascular disease prevalence is needed because CAC improves CAD risk stratification, and the knowledge of CAC enhances medication adherence and motivates individuals towards beneficial behavioral/lifestyle modification.