- A-Z Publications
- Cardiovascular Journal of South Africa
- Previous Issues
- Volume 13, Issue 4, 2002
Cardiovascular Journal of South Africa - Volume 13, Issue 4, 2002
Volume 13, Issue 4, 2002
Author A.J. BrinkSource: Cardiovascular Journal of South Africa 13 (2002)More Less
Extracted from text ... The guest editor for this issue of the Cardiovascular Journal of South Africa is Professor Stephen Hough, Head of the Endocrine Unit and Chairman of the Department of Medicine at the Faculty of Health Sciences, University of Stellenbosch and Tygerberg Hospital. He has extensive local and international recognition for research that is mostly related to osteoporosis. He is Founder/President of the Osteoporosis Foundation of South Africa and also Scientific Editor of JEMDSA, the Journal of the Society of Endocrinology, Metabolism and Diabetes of South Africa. In this issue of the Cardiovascular Journal, Prof. Hough has brought together scientific contributions from ..
Author S. HoughSource: Cardiovascular Journal of South Africa 13, pp 151 –154 (2002)More Less
Extracted from text ... Coronary heart disease (CHD) is the leading cause of death in elderly women. During the past 50 years several lines of evidence converged to suggest that this could be attributed largely to the decrease in oestrogen levels that attends the postmenopausal state, and that correction of this deficiency might prevent heart disease. Postmenopausal oestrogen is the second most commonly prescribed prescription drug in the United States, and in South Africa, the current hormone replacement therapy (HRT) market has a turnover of R232 million and a growth in excess of 30%. Should HRT therefore be recommended for all postmenopausal women, and ..
Author Y.K. SeedatSource: Cardiovascular Journal of South Africa 13, pp 156 –157 (2002)More Less
Extracted from text ... Our knowledge of the importance of endocrine hypertension was recognised by a landmark study in the U.S. This was the Framingham study. 1 Today there is irrefutable evidence of the importance of metabolic diseases as risk factors in coronary heart disease and strokes. In 1949, cardiovascular disease accounted for half of the deaths recorded in the U.S. The observed decline in infant mortality was having little effect on the life expectancy over the age of 45, in whom degenerative diseases were taking a heavy toll. In order to clarify the situation where some doubted that half of all mortality could ..
Author W. NelsonSource: Cardiovascular Journal of South Africa 13, pp 157 –163 (2002)More Less
Extracted from text ... The answer is provided on page 163. By Prof William Nelson MD, Clinical Professor of Medicine at the University of Colorado School of Medicine and Director of Cardiology Education, St Joseph Hospital, Denver. The reviewer noted the following on the ECG of the 82-yearold man: How many observations? What does 'bidirectional bigemini' suggest? The ECG The sinus stimuli are conducted with R.B.B.B. and are coupled to VPCs ventricular bigemini. The frontal plane preblocked axis is () 60 degrees and there are large intitial R waves in V2-3. The combination is consistent with an inferoposterior M.I. of uncertain age. Note that the ..
Author J.A. MoolmanSource: Cardiovascular Journal of South Africa 13, pp 159 –163 (2002)More Less
Thyroid hormone has important cardiovascular effects, and abnormalities of its production cause cardiovascular morbidity. The role of both excessive and insufficient thyroid hormone production in the pathogenesis of clinical cardiac diseases can be deduced from thyroid hormone-induced molecular changes. Thyroid hormone regulates the expression of myocardial genes regulating the handling of calcium, which affects both systolic and diastolic myocardial function. Thyroid hormone also has indirect and direct effects on peripheral vascular smooth muscle tone, and alters the coupling of the left ventricle and arterial system. Excessive production of thyroid hormone results in an increased cardiac output as well as increased cardiac work efficiency, but reduced cardiac reserve.
Amiodarone therapy for cardiac rhythm can cause both hyper- and hypothyroidism. Amiodarone-induced thyrotoxicosis (AIT) can be due to either excessive thyroid hormone production (type I AIT) or thyroid hormone release due to an inflammatory condition (type II AIT). Classification of AIT is helpful in guiding therapy. Amiodarone causes changes in the thyroid function tests of euthyroid patients on therapy - it inhibits the conversion of T4 to T3, which results in decreased T3 and slightly increased T4 serum levels in euthyroid patients. Baseline thyroid functions should therefore be determined before starting amiodarone therapy, and at 6- monthly intervals thereafter.
Author Brian L. RaynerSource: Cardiovascular Journal of South Africa 13, pp 166 –170 (2002)More Less
Primary aldosteronism (PA) is the commonest form of secondary hypertension in South Africa with an approximate prevalence of 7.5% in the primary-care setting. Hypokalaemia is a poor screening test with 70% of proven cases having normal serum potassium levels. The aldosterone / renin ratio is a robust screening test with a high sensitivity and specificity, but in South Africa this should be combined with an absolute aldosterone level because of the high incidence of low-renin hypertension in Blacks. The limitations of the ratio, especially with regard to concomitant drug therapy will be discussed in detail. The fludrocortisone suppression test remains the investigation of choice for confirming the diagnosis, but requires four days of hospitalisation. CT scanning will miss 50% of adenomas and incorrectly lateralise the adenoma in occasional cases, and bilateral adrenal venous sampling is the gold standard for indirectly confirming an adenoma by demonstrating lateralisation of aldosterone secretion, but its use is limited by lack of technical expertise in South Africa. Low-dose spironolactone is the medical therapy of choice for PA.
Author Lionel H. OpieSource: Cardiovascular Journal of South Africa 13, pp 171 –178 (2002)More Less
The syndrome of heart failure is still imperfectly understood. It is defined as effort intolerance caused by heart disease, often with a neuroendocrine response that leads to fluid retention and promotes an adverse vicious circle. The cause of this response is generally thought to be a low blood pressure, leading to adrenergic and reninangiotensin activation. The result is increased peripheral vasoconstriction, which maintains the blood pressure while punishing the already failing myocardium by demanding more work against the increased afterload. The evolution of heart failure is traced out from an initial pressure or volume overload that initiates a series of growth signals to cause myocardial growth. Why the apparently well-compensated LV should degenerate into failure is not clear, but impaired coronary flow reserve and excess angiotensin II activity with fibrosis and apoptosis all probably play a role. The collagen matrix normally limits cardiac chamber expansion so that matrix remodeling under the influence of matrix metalloproteinases is required for the LV to enlarge in volume. Regarding the neuroendocrine response, excess adrenergic activity promotes failure by myocardial membrane damage and calcium overload, and by increasing the myocardial oxygen demand and the afterload. Beta2- adrenergic stimulation may (unexpectedly) be antiapoptotic and cardioprotective. Activation of the reninangiotensin system (RAS) is clearly very harmful, as shown by numerous studies in which inhibiting agents have reduced human mortality. Specific adverse consequences of RAS activation include (1) excessive peripheral vasoconstriction; (2) aldosterone-mediated sodium retention and myocardial fibrosis; (3) increased endothelial damage; and (4) excessive angiotensin II effects at intracellular sites. Other neuroendocrine changes are increased levels of endothelin and of cytokines such as tumour necrosis factor-alpha. Ergoreflexes from the ailing skeletal muscle may further promote adrenergic and RAS activation. Conversely, increased release of natriuretic peptides from the left heart is cardioprotective by limiting fluid retention and promoting vasodilation. Current therapies of heart failure are largely based on inhibition of the neuroendocrine response.
Source: Cardiovascular Journal of South Africa 13, pp 179 –180 (2002)More Less
The developing world is experiencing a rise in the prevalence of obesity, diabetes and cardiovascular disease to such an extent that it is often described as an epidemic. The most common explanation advanced for this phenomenon is the so-called epidemiological transition, with the biological basis of the thrifty genotype. The thrifty genotype theory suggests that genes derived from times of deprivation may result in adaptations that have adverse effects in times of plenty. However, a divergent theory is the so-called foetal origins of chronic disease which ascribes the epidemic, in part, to an adverse intrauterine environment. There is compelling evidence, based on large numbers of epidemiological studies conducted in both developing and developed countries, that small size at birth in full-term pregnancies is linked with the subsequent development of the major features of the metabolic syndrome, namely glucose intolerance, increased blood pressure, dyslipidaemia and increased mortality from cardiovascular disease.
Source: Cardiovascular Journal of South Africa 13, pp 181 –186 (2002)More Less
The metabolic syndrome is a highly prevalent clinicalentity, which is often overlooked and may have far-reaching health implications for the patient. Up to 80% of patients with the metabolic syndrome die as a result of cardiovascular complications. Insulin resistance is the central component of this complex syndrome and should be appropriately addressed to ensure the best possible outcome for our patients.
Recent advances in the pathogenesis and management of this syndrome is discussed in this article.
Author B. Ascott-EvansSource: Cardiovascular Journal of South Africa 13, pp 187 –188 (2002)More Less
In westernised societies the metabolic syndrome (MS) is common and primarily a lifestyle disease with significant morbidity and premature mortality. The main endpoints are related to cardiovascular disease (CVD), especially affecting the heart.
Although insulin resistance (and hyperinsulinaemia) is an early marker of MS and future adverse cardiovascular outcomes, it is not known if on its own this is sufficient. The issue is further clouded in prospective studies by the development in study subjects of some, or all of the components of MS, each of which is an independent risk factor for CVD!
Therefore, in spite of a number of appropriate long-term observational studies, we are unable to tease out the exact contribution of the individual components of MS, which together are unequivocally responsible for this present-day epidemic of CVD.
Author A.F. DoubellSource: Cardiovascular Journal of South Africa 13, pp 189 –193 (2002)More Less
Coronary artery disease is common in diabetic patients and remains the major cause of death in these patients. However myocardial ischaemia resulting from coronary lesions does not always give rise to symptoms. The managing physician must therefore consider the benefit of screening for silent myocardial ischaemia in diabetic patients. Screening all diabetic patients is not recommended. The challenge to the physician is to select the patient subgroups likely to benefit from screening. Patients with more than one cardiac risk factor (dyslipidaemia, hypertension, smoking, family history, microalbuminuria) in addition to diabetes, as well as patients with established macrovascular disease, e.g. peripheral vascular disease, will benefit most from screening. A standard treadmill stress ECG is the recommended screening test.
A number of additional tests have been proposed to select high-risk patients for screening. Of these, testing for microalbuminuria and elevated CRP levels are most likely to influence decision-making.
Once silent ischaemia has been detected in a diabetic patient, the mainstay of treatment remains the aggressive control of risk factors, improvement of glycaemic control and aspirin therapy. The use of beta-blockers and ACE inhibitors often need consideration. The attending physician must then consider referring the patient to a cardiologist for angiography and possible intervention. This decision is based on the presence of poor prognostic signs during the stress ECG and the number of risk factors present. Microalbuminuria and elevated CRP levels are helpful in assisting with the risk stratification process.
The link between microalbuminuria, endothelial dysfunction and cardiovascular disease in diabetes : review articleAuthor D.P. NaidooSource: Cardiovascular Journal of South Africa 13, pp 194 –199 (2002)More Less
Microalbuminuria (MA), i.e. slightly elevated albumin excretion in the urine, is now considered to be an atherosclerotic risk factor. MA predicts future cardiovascular disease in diabetic patients, in elderly patients, as well as in the general population. It has been implicated as an independent risk factor for cardiovascular disease and premature cardiovascular mortality for patients with type 1 and type 2 diabetes mellitus, as well as for patients with essential hypertension.
Although microalbuminuria is associated with a certain degree of sub-clinical atherosclerotic damage, it is not known how early in the atherosclerotic process microalbuminuria appears. Epidemiological studies have shown an association between MA and insulin resistance, obesity, salt sensitivity and dyslipidaemia in patients with essential hypertension and diabetes. Patients with microalbuminuria are also characterised by an increased prevalence of left ventricular hypertrophy and retinal microvascular lesions. Microalbuminuria is associated with an excess of other cardiovascular risk factors. The mechanisms linking microalbuminuria and risk for cardiovascular disease are not fully understood, but in subjects at risk it may be related to increased transvascular leakiness of albumin in systemic as well as renal vessels. A recent concept is that albuminuria is a marker of extensive endothelial dysfunction or generalised vasculopathy, which may lead to heightened atherogenic states. One possible explanation is that endothelial dysfunction might promote increased penetration of atherogenic lipoprotein particles in the arterial wall, but glycaemic status, insulin resistance, procoagulant state and adhesion molecules have all been implicated in the pathogenesis.
Current evidence suggests that tight blood pressure control may reduce the risk of microalbuminuria in diabetic patients with hypertension and that inhibitors of the renin-angiotensin system (RAS) can prevent or delay the progression of microalbuminuria to overt nephropathy in normotensive persons. ACE inhibitors are currently recognised as first-line antihypertensive therapy in diabetic patients with proteinuria, and these agents afford unique benefits in modifying the progression and severity of cardiovascular disease (CVD) as well as of diabetic nephropathy.
Whether albuminuria is a risk factor or just a marker for CV disease, it identifies the high-risk diabetic patient who should be targeted for early, aggressive intervention against proven risk factors. If persistent microalbuminuria is confirmed, strict blood pressure control with added RAS inhibition should be pursued in an attempt to stabilise or even reduce microalbuminuria, preserve kidney function and possibly improve cardiovascular risk.
Author Frans. J. MaritzSource: Cardiovascular Journal of South Africa 13, pp 200 –203 (2002)More Less
The statins are among the most widely used pharmaceutical drugs and have been shown to be extremely effective in the treatment of dyslipidaemia. The statins are effective in the primary and secondary prevention of coronary artery disease, in peripheral and cerebral vascular disease and in a wide variety of patient groups. In addition they have a beneficial effect on the vascular wall and atherosclerotic process, which is not related to their cholesterol-lowering effect. Despite their potency they are relatively well tolerated, with adverse effects mostly as a result of muscle and liver involvement. Some of the issues relating to efficacy and detrimental effects are discussed briefly.
Author K.R.L. HuddleSource: Cardiovascular Journal of South Africa 13, pp 205 –209 (2002)More Less
Endocrine causes of hypertension are relatively rare, buttheir detection offers a real chance for cure. This is particularly true of phaeochromocytoma, a catecholamine- producing tumour derived from chromaffin tissue, which, if left undetected, is invariably fatal. The lethal nature of this tumour is dependent on two major characteristics: firstly, its ability to secrete catecholamines in excess, resulting in potentially catastrophic consequences; and, secondly, its malignant potential. Approximately 5-10% of these tumours are malignant, which, if metastasised, are generally refractory to treatment. Clearly, however, because only one in 1 000 hypertensives is likely to harbour a phaeochromocytoma, it is not a cost-effective option to screen all hypertensives for this cause. Rather, a selective approach is preferred in which a high index of suspicion for the clinical characteristics of this tumour is used to guide the physician. The following two case reports derived from our records at Chris Hani Baragwanath Hospital will illustrate many issues related to diagnosis and management of this fascinating tumour.
Source: Cardiovascular Journal of South Africa 13, pp 211 –213 (2002)More Less
Extracted from text ... New drug therapies may, for the first time, offer patients and their physicians an opportunity to halt the seemingly inevitable progression of diabetes by targeting the correct underlying defects, according to Dr Leif Groop of Lund University, Sweden. Treatment of diabetes should start as early as possible, at 6 mmol/l fasting plasma glucose (FPG) or before. By the time the traditional levels of diabetes diagnosis are reached (7 mmol/l FPG), about 50% of patients already show signs of cardiovascular complications. Dr Groop presented a comprehensive review of the treatment and mistreatment of type 2 diabetes, concluding with a personal view ..
Source: Cardiovascular Journal of South Africa 13, pp 214 –215 (2002)More Less
Extracted from text ... Glimepiride well tolerated in daily practice The efficacy and tolerability of glimepiride (Amaryl) has recently been highlighted in an extensive study of more than 20 000 patients with type 2 diabetes attending 4 000 primary care practices in Germany. Glimepiride is classed as a sulphonylurea for the oral therapy of type 2 diabetes mellitus. Its main action is the release of insulin from pancreatic ? cells. Glimepiride specifically binds to a membrane protein close to the potassium channel of the ? cell membrane and reduces the opening probability of this channel. The resulting depolarisation opens voltagedependent calcium channels and ..
Source: Cardiovascular Journal of South Africa 13, pp 215 –216 (2002)More Less
Extracted from text ... Reducing dementia and cognitive decline in stroke patients Blood pressurelowering therapy based on the longacting ACE inhibitor perindopril reduces by onethird the risk of dementia and by nearly a half, the risk of severe cognitive decline following recurrent stroke, according to new data from the landmark PROGRESS (Perindopril pROtection aGainst REcurrent Stroke Study) presented at the International Society of Hypertension (ISH) meeting. These findings supplement the main results of the PROGRESS study that demonstrated overall reductions of onequarter to onethird in the risk of recurrent strokes and heart attacks among hypertensive and nonhypertensive stroke patients given perindopril based antihypertensive ..
Source: Cardiovascular Journal of South Africa 13, pp 216 –217 (2002)More Less
Extracted from text ... EC approves irbesartan for the treatment of diabetic renal disease. BristolMyers Squibb Company (NYSE: BMY) and SanofiSynthelabo (Paris Bourse: Sicovam code 12057) have announced that the European Commission has approved irbesartan (Aprove?/Karve?) in the European Union for a new indication: the treatment of renal disease in people with hypertension and type 2 diabetes mellitus (as part of a antihypertensive drug regimen). Irbesartan is the first blood pressurelowering drug approved across the European Union for treatment of both early and latestage diabetic renal disease in hypertensive type 2 diabetic patients. Irbesartan, an angiotensin II receptor antagonist (AIIRA), is already indicated for ..
Source: Cardiovascular Journal of South Africa 13, pp 218 –219 (2002)More Less
Extracted from text ... Early lytic treatment of massive pulmonary embolism. Administering the clotdissolving drug alteplase (Actilyse (r) Boehringer Ingelheim) early in the course of massive pulmonary embolism prevents worsening of the disease, a new clinical trial has shown. Patients who benefited from the treatment had signs of rightheart strain at presentation (their hearts were labouring to function despite the presence of emboli or clots obstructing the pulmonary arteries), but appeared haemodynamically stable (that is, they had normal blood pressure). Previously, it was believed that thrombolytic therapy should be reserved for sicker patients those whose rightheart strain had progressed to cardiogenic shock or other ..
Source: Cardiovascular Journal of South Africa 13 (2002)More Less
Extracted from text ... Cardiovascular risk reduction with pioglitazone Type 2 diabetes is associated with a characteristic pattern of lipid abnormalities. Features of the dyslipidaemia include elevated triglycerides and reduced levels of highdensity lipoprotein (HDL). Plasma levels of lowdensity lipoprotein (LDL) do not differ from those of nondiabetic people, but there is a qualitative change in that there is an increase in triglyceriderich small, dense LDL particles. Coupled with hyperglycaemia, these lipid abnormalities are associated with an increased risk of cardiovascular complications. The thiazolidinediones (TZDs) are a relatively new class of oral hypoglycaemic agents, which provide effective longterm glycaemic control in patients with type 2 ..