3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Clinical appropriateness of referrals to the echocardiography clinic at the Chris Hani Baragwanath academic hospital(2017) Dube, FaraiBackground South Africa is grappling with a quadruple burden of disease, and cardiovascular diseases with other non-communicable diseases are on the increase. Echocardiography is an expensive but vital basic screening and diagnostic tool for cardiac patients. Appropriate use criteria (AUC) have been developed for echocardiography to assist with avoiding unnecessary echocardiograms. Aim and Objectives of the study The aim of the study was to determine the clinical appropriateness of referrals to the echocardiography clinic at Chris Hani Baragwanath Academic Hospital using AUC. The specific objectives were: 1. Describe the socio-demographic profile of patients referred for echocardiography 2. Determine the clinical appropriateness of echocardiography referrals 3. Describe the clinical profile of patients referred for echocardiography 4. Determine whether socio-demographic and clinical profile influence the appropriateness of echocardiography referral Methods During July 2015, a cross-sectional study was conducted among all new patients referred to the echocardiography clinic at the Chris Hani Baragwanath Academic Hospital (CHBAH). Following informed consent, patient demographic information was collected. Clinical and echocardiography reports were obtained for all new patients and analyzed, using the 2011 AUC criteria for echocardiography. The data were analysed using Minitab version 16. Results The majority of the study participants (n=270) were black African (88.3%); they had a mean age of 53 years (SD ±16.6) and 63.1% were female. The study found that 93.3% of new patients were appropriately referred, 3.7% (n=10) were inappropriately referred and 3.0% (n=8) had uncertain indications for echocardiography. Hypertension 45.5% (n=123/270) was the most common clinical diagnosis on echocardiogram request, with the post-echocardiogram evaluation confirming that 41.6% (111/267) of all the patients had hypertensive heart disease. An HIV positive status was documented in only 10.6% (n=29) of the patients. Conclusion The AUC is a useful tool and yielded similar results at the CHBAH. There is a high burden of hypertensive heart disease in this population, which requires specific prevention strategies.Item Myocardial deformation in African hypertensive patients with heart failure : an analysis using speckle tracking echocardiography(2014-09-08) Maharaj, NirvarthiHypertension and heart failure are intimately related with the incidence of heart failure among hypertensive subjects between 1% and 2% per year. Structural and functional myocardial abnormalities identified in hypertensive patients contribute to the progression of myocardial dysfunction. Systolic abnormalities in hypertension begin to develop in the early stages of the disease despite normal left ventricular (LV) ejection fraction (EF) and contribute to the progressive deterioration of LV systolic performance. However, these systolic abnormalities are initially not detectable by conventional echocardiographic methods. Speckle tracking echocardiography (STE) is a sensitive quantitative technique for assessing LV function. LV twist is an important contributing factor to the systolic function of the LV in health and disease and may be a better index of systolic function than ejection fraction (EF) in hypertensive patients (HTP). The remodelling process of the left ventricle in hypertension entails a complex interplay between myocyte hypertrophy and dysfunction, with qualitative changes in the extracellular matrix contributing to progressive dysfunction. Adverse LV remodeling in HTP is associated with an imbalance in collagen degradation and may contribute to the remodelling phenotype and systolic dysfunction in hypertension. Increased matrix metalloproteinase-1 (MMP1) levels contribute to development of LV dilatation and failure with higher levels of MMP1 in the myocardium of hypertensive patients with low EF than those with normal EF. Hypertension can cause systolic dysfunction as a consequence of adverse remodelling and LV hypertrophy, but given the multitude of factors involved in LV decompensation mediated by mechanical, neurohormonal and cytokine routes, the exact mechanisms that contribute to the adverse remodelling and EF deterioration are not fully elucidated. LV twist may be a contributing factor to systolic dysfunction independent of other factors, thus, a focus on abnormalities in the cardiac mechanics of twist in the left ventricle may be helpful in understanding the pathogenesis behind the transition from compensated to decompensated heart failure. Furthermore, the changes in the extracellular matrix may account for the varying morphology, EF and LV twist in HTP. The purpose of this thesis was to 1) determine LV twist in healthy adults of different age groups (n=127), 2) evaluate LV twist changes in African HTP with low (EF<50%) and preserved EF (EF ≥ 50%) (n=82) and 3) examine the relationship between LV twist and biomarkers of collagen degradation in HTP with preserved and low EF. Parasternal short-axis images of three consecutive end-expiratory cardiac cycles at LV basal and apical levels were obtained. Apical rotation (AR) and basal rotation (BR) during ejection and instantaneous LV peak systolic twist (net twist, defined as maximal value of instantaneous AR minus BR) were measured. 127 normal subjects were divided into four age groups: 20-29 (n=34); 30-39 (n=33); 40-49 (n=29); and 50-65 (n=31) years. LV twist and markers of collagen turnover (serum concentrations of matrix metalloproteinase -1 (MMP1), tissue inhibitor of MMP1 (TIMP1) and ratio of MMP1:TIMP1) were measured in 82 hypertensive patients, 41 with EF < 50% (HTLEF) and 41 with EF ≥ 50% (HTNEF). Rigid body rotation (RBR) was defined as AR and BR occurring in the same direction. Serum biomarkers were log transformed before analysis. LV twist increased with age in normal subjects. Multivariate linear regression analysis showed age as the main predictor of net LV twist (R2=0.82, P<0.0001) in normal subjects. Net LV twist was lower in HTLEF compared with HTNEF (3.34 + 1.10 vs. 11.70 + 0.67, p < 0.0001). Of 41 HTLEF patients, 28 (68%) had normal twist pattern while 13 (32%) exhibited RBR. The subgroup with RBR showed greater LV dysfunction (EF: 27.9±5.8% vs. 35±7.5%; p=0.005) and more spherical LV geometry (p=0.0009) compared with those who had normal pattern of twist. Log TIMP1, Log MMP1 and Log MMP1:TIMP1 ratio levels were higher in HTLEF compared with HTNEF (12.32 ± 0.25 vs. 11.81 ± 0.13, p<0.0001; 9.08 ± 0.32 vs. 8.00 ± 0.18, p<0.0001; -3.25 ± 0.30 vs. -3.81 ± 0.18, p<0.0001; respectively). There was an inverse correlation between Log MMP1:TIMP1 and net LV twist after adjusting for EF (r = -0.41, p <0.0001). This study established normative data and patterns for myocardial deformation (strain and LV twist) in a normal black-African adult population across different age groups and can be used as a baseline for future studies. Age was the major determinant of increased LV twist in a normal black population. LV twist may be a compensatory mechanism to preserve EF and maintain normal systolic function with advancing age and in hypertension. LV twist varies with the degree of remodeling and systolic function in hypertension. RBR represents a novel assessment of more severe LV remodeling and LV systolic dysfunction in hypertensive patients. Alterations in collagen turnover not only accompanies more adverse remodelling but also contributes to LV twist differences observed between HTLEF and HTNEF patients. The inverse relation between LV twist and loss of myocardial collagen scaffolding suggests that integrity of the extracellular matrix may play an important role in preservation of LV twist. These findings highlight the value of LV twist as a sensitive global parameter of LV systolic myocardial performance. Longitudinal studies assessing LV twist may provide significant value in clinical practice as an early marker for risk stratification in hypertensive patients who may benefit from aggressive medical therapy to prevent LV remodelling and heart failure.Item An analysis of myocardial deformation with speckle tracking echocardiography in black patients on haemodialysis(2014-02-10) Yip, AnthonyCardiac disease is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD). Accurate evaluation of cardiac function is therefore important but difficult with commonly used imaging modalities such as echocardiography being subject to variable load changes in haemodialysis.Item Risk factors for atherosclerosis in black South African patients on Haemodialysis(2006-11-08T08:53:51Z) Amira, Christiana OluwatoyinABSTRACT INTRODUCTION The risk of cardiovascular disease in patients with end stage renal disease (ESRD) is far greater than in the general population. Amongst patients with ESRD, the prevalence of coronary artery disease (CAD) and congestive heart failure is approximately 40% compared with 5-12% in the general population. The excess risk is caused by multiple traditional and non-traditional risk factors for ischaemic heart disease present in these patients. There is little information on CAD and its risk factors in black haemodialysis patients as most of these studies were carried out in the white population. This study is therefore aimed at determining the risk factors for atherosclerosis in Black and non-black (White and Indian) South African patients on haemodialysis. METHODS Fifty-eight black patients and twenty-six non-black patients on haemodialysis were recruited. Sixty-three age and sex matched controls (staff, students and kidney donors) were also recruited. Fasting venous blood samples were drawn for measurement of Creactive protein, homocysteine, Lp (a), serum lipids and adiponectin. Carotid intima-media thickness and plaque occurrence was measured by B-mode ultrasonography. Echocardiography was used to determine LVH. vi RESULTS Haemodialysis (HD) patients had significantly lower total cholesterol, LDL cholesterol and triglycerides compared with controls (p<0.001; p= 0.042). Hs-CRP, adiponectin and homocysteine levels were significantly higher in patients compared with controls (p< 0.001). The prevalence of plaques was significantly higher among HD patients (32%) compared with controls (7%) X2 = 60.72 p< 0.001. LVMI was significantly higher among HD patients (194.25± 7.69gm/m2) compared with controls (93.21 ± 3.27 gm/m2) p < 0.001. No significant difference between patients (Black or Asian/White) and controls with respect to CIMT was found. CVD risk factors in black haemodialysis patients and black controls showed a similar pattern to the whole study population combined. Risk factors associated with CIMT on regression analysis were total cholesterol, LDL-cholesterol, age, Hs-CRP, family history of CKD. Risk factors associated with plaque occurrence on logistic regression analysis were age, systolic blood pressure, male gender, smoking, calcium phosphate product and serum phosphate. CONCLUSION HD patients have a high prevalence of traditional and non-traditional risk factors for atherosclerosis and this is independent of race. Traditional risk factors like lipids were much lower in ESRD patients. HD patients showed a high prevalence of atherosclerosis as measured by increased carotid intima-media thickness and plaque occurrence in carotid arteries. Hs-CRP correlated significantly with a surrogate marker of atherosclerosis (CIMT).