Endothelial nitric oxide synthase levels and their response to exercise in patients with slow coronary flow

Slow coronary flow (SCF), described for the first time by Tambe and his colleagues in 1972, is an angiographic diagnosis characterised by a low rate of flow of contrast agent in the epicardial coronary arteries, together with typical angina pectoris and normal coronary arteries.1 Even though micro- and macrovascular disease findings have been identified, such as myofibrillar hypertrophy, myofibrillar degeneration, hyperplastic fibromuscular thickening, luminal narrowing, endothelial degeneration, endothelial dysfunction and diffuse atherosclerosis, which may lead to reduced coronary flow reserve, uncertainties still exist in the aetiopathogenesis.2,3Coronary blood flow and oxygen transport to the myocardium are increased by autoregulatory mechanisms for the increased metabolic needs associated with effort. The amount of oxygen extracted from the blood also increases, which leads to a decrease in the concentration of oxygen in the blood. Mitochondrial metabolism is altered by coronary endothelium-derived nitric oxide (NO) in an attempt to reduce the growing energy requirements.4,5Vascular endothelium exhibits a number of haemostatic functions in normal blood vessels. NO is a key molecule for normal autoregulatory mechanisms, such as modulating the vasodilator response to tachycardia and exercise,6 and it has also been found to be essential for flow-mediated dilatation of large human arteries in vivo.7 Endothelial nitric oxide synthase (eNOS) is an enzyme involved in the synthesis of NO.8 Decreased plasma eNOS level is an important indicator of endothelial dysfunction.9To our knowledge, there has been no study evaluating plasma eNOS levels and their response to exercise in SCF patients. Therefore we aimed to investigate the plasma levels of eNOS before and after exercise in patients with SCF.     

Vitamin E and antioxidant activity; its role in slow coronary flow

The ability of antioxidant defense to scavenge reactive oxygen species (ROS) is important to protect tissues from oxidative damage. Cells and biological fluids have an array of protective antioxidant mechanisms, enzymatic (superoxide dismutase, catalase, glutathione peroxidase) and non-enzymatic, referred to as chain-breaking antioxidants (tocopherols, ubiquinol, carotenoids and flavonoids as lipid phase, and ascorbate, urate, glutathione and other thiols as aqueous phase), both for preventing the production of free radicals and for repairing oxidative damage.1-4A free radical contains an unpaired electron in an atomic orbital. In this state, no molecular species is stable for long. A free radical will attract other molecules and either give or receive an electron to make itself thermodynamically stable.5 The most important free radicals in many disease states are oxygen derivatives such as hydrogen peroxide, superoxide and particularly, hydroxyl radical, which is the most harmful for tissues.1Transition metals contain one or more unpaired electrons and are therefore also radicals when in the elemental state. However, their key property from the point of view of free radical biology is their variable valency, which allows them to undergo reactions involving the transfer of a single electron. The most important transition metals in human disease are iron and copper.6 These elements play a key role in the production of hydroxyl radicals in vivo.7Hydrogen peroxide and superoxide can be detoxified enzymatically in the mammalian system by catalase and superoxide dismutase, respectively. However there is no enzymatic system that converts or detoxifies hydroxyl radicals. A hydroxyl radical can be detoxified by non-enzymatic systems. One of these is the tocopherols (α, β, γ and δ), which have a chromanol ring and a phenyl tail, and differ in the number and position of the methyl groups on the ring. The most important lipid-phase antioxidant is probably vitamin E.8-10The coronary slow-flow phenomenon was first described in 1972 by Tambe et al.11 The phenomenon is an angiographic finding characterised by delayed distal vessel opacification in the absence of significant epicardial coronary disease. However, since that time, only a limited number of studies have focused on the aetiology of this unique angiographic phenomenon.Histopathological studies have revealed the loss of luminary diameter, and capillary and endothelial damage in these patients.12 Although the pathophysiological mechanisms of slow coronary flow phenomenon remain uncertain, there are several hypotheses that have been suggested, including endothelial activation and inflammation.13 However, the phenomenon is not well studied and deserves further investigation.In the present study, we investigated plasma vitamin E levels and antioxidant activity in patients with slow coronary flow (SCF) and compared them with those with normal coronary flow (NCF).     

Simultaneous coronary artery bypass grafting and carotid endarterectomy can be performed with low mortality rates

There is controversy over the best approach for patients with concomitant carotid and coronary artery disease.1 Therapeutic strategies include isolated coronary artery bypass grafting (CABG), staged carotid endarterectomy (CEA) and CABG, reversed staged CEA and CABG, and simultaneous procedures under single anaesthesia.2Although reported experiences over three decades are available, combining CEA with CABG remains to be elucidated.3 Furthermore, risk of cerebrovascular accident (CVA), which is one of the major predictors of prognosis of CABG, has been reported to increase up to 14% in patients with severe carotid artery stenosis (> 80%).4-9Peri-operative neurological events such as stroke after CABG are the major neurological complications, which increase with age.10 The incidence of peri-operative stroke has been well documented at approximately 2% of all cardiac surgeries.11 Despite reduced overall complication rates over the years after CABG, the incidence of stroke remains relatively unchanged.10The aetiology of peri-operative stroke is multi-factorial including hypotension or hypoperfusion-induced reduced brain flow, atherosclerosis due to micro- or macro-embolisation, and intra- or extra-cranial vascular diseases.5 In addition, carotid artery disease is a critical factor; however, it is considered unlikely to be the only culprit for peri-operative strokes.12Although no consensus on the optimal management of patients with concomitant carotid and coronary artery disease has been reached,13 simultaneous CEA and CABG surgery is often associated with low rates of mortality and morbidity.14-17 In this study, we report our experience with simultaneous CEA and CABG surgery in our clinic in the light of data in the literature.     

Ambulatory blood pressure profiles in a subset of HIV-positive patients pre and post antiretroviral therapy

South Africa has 5.6 million people living with HIV/AIDS and has the largest antiretroviral therapy (ART) programme globally, with more than two million people accessing ART.1 Although ART has significantly decreased the mortality rate from HIV infection, these individuals are now living longer and are at risk of developing metabolic (dyslipidaemia, lipodystrophy, dysglycaemia), cardiovascular and renal complications from ART and chronic exposure to HIV infection.2-7Chronic HIV and ART are associated with increased risk of developing hypertension.8 In studies of HIV-positive patients in high-income countries, hypertension prevalence ranges from 13 to 34%.9,10 However, data from low- and middle-income countries remain sparse.Nocturnal blood pressure (BP) is superior to daytime or office BP as a predictor of cardiovascular disease.11 Non-dipping is defined as an abnormal diurnal rhythm manifested by a blunted nocturnal decline in systolic BP (SBP).11 It is associated with more severe hypertensive target-organ damage (left ventricular hypertrophy, microalbuminuria and cerebrovascular disease) and is also a predictor of increased cardiovascular risk, both in hypertensive and normotensive populations.11Studies from high-income countries have shown an increased prevalence of non-dipping with HIV infection.9,12 However, the participants in these studies were largely white, middle-aged males. Since the majority of subjects with HIV infection in sub-Saharan Africa are young black females, it is not known whether the same relationship between dipping status and HIV infection would be found. In addition, there are data showing that black HIV-negative individuals have less nocturnal dipping compared to their white counterparts.5,13,14Therefore, the aims of this study were to document the prevalence of chronic kidney disease (CKD) and hypertension at baseline (ART naïve) in a healthy HIV-positive cohort, and to assess changes in these parameters after six months on ART. The characteristics of ambulatory blood pressure (ABP) in a subset of patients were to be recorded and compared to a control group of HIV-negative patients.     

The incidence of coronary anomalies on routine coronary computed tomography scans

The incidence of coronary anomalies (CCAs) in a typical angiographic study was 1.3%.1 Studies have been conducted on CCAs using conventional invasive coronary angiography in highly selected groups of patients but these studies may not reflect the true incidence of CCAs.Although the majority of CCAs are benign and incidentally detected during conventional angiography, certain CCAs may cause syncope, heart failure or sudden death, especially among young athletes.2,3 The US National Registry of Sudden Death in Athletes at the Minneapolis Heart Institute Registry found that CCAs were the second most common cause of sudden cardiac death (out of 17% of the population who died of cardiac-related causes).4Although conventional invasive coronary angiography is considered the gold standard for the diagnosis of CCAs, transthoracic two-dimensional echocardiography, transoesophageal echocardiography, magnetic resonance imaging and multi-slice computed tomography (MSCT) can all identify for diagnosis, CCAs in certain groups of patients.5-10 Transthoracic twodimensional echocardiography may depict the origin of the coronary arteries, especially the left main artery, but successful detection of coronary anomalies depends on the age and size of the patient.5,6Transoesophageal echocardiography has an increased success rate of identifying coronary anomalies in comparison with two-dimensional echocardiography. Nevertheless, the position of the transducer, cardiac motion, and the curvilinear course of the vessel all affect visualisation of coronary anomalies. Moreover, transoesophageal echocardiography is a semi-invasive method and is time consuming.6,7Magnetic resonance (MR) imaging provides an accurate assessment of the course of anomalous coronary arteries.8,9 However, this technique cannot be performed in patients with pacemakers, certain types of arrhythmias or defibrillating devices, and it may be difficult to perform in claustrophobic patients. Furthermore, the spatial resolution of MR imaging is substantially inferior to that of the newest generation of CT scanners.10Myocardial bridging (MB) is defined as the compression of a coronary artery during systole while it is normal in diastole. MB has been linked to serious cardiac events.11 The incidence of myocardial bridging in the population varies substantially according to invasive coronary angiography (13%) and autopsy (15–85%).12,13 The reported incidence of MB has increased up to 44% when using 64-MSCT.14 Because of its ability to cause serious cardiac events, diagnosing MB is clinically important.MSCT is a minimally invasive method that provides excellent temporal and spatial resolution of the coronary arteries. There have been a limited number of studies evaluating CCAs and MB with 64-MSCT. The aim of this study was to assess the incidence of CCAs and MB using 64-MSCT in a relatively large population.     

Sickle cell trait is not associated with chronic kidney disease in adult Congolese patients: a clinic-based,cross-sectional study

Chronic kidney disease (CKD) and end-stage renal disease (ESRD) are associated with significant cardiovascular (CV) and renal morbidity and mortality rates, with substantial economic burden.1,2 Therefore, early identification of CKD patients at high risk of progression is urgently needed for early and targeted treatment to improve patient care.1-3 Diabetes and hypertension are the primary risk factors for CKD and ESRD but do not fully account for CKD and ESRD risk.1-3 Marked variability in the incidence of CKD suggests that factors other than diabetes and hypertension contribute to its aetiology.4Family studies have suggested a genetic component to the aetiology of CKD and ESRD.5 In African Americans, high-risk common variants in the Apol1/MYH9 locus may explain up to 70% of the differences in ESRD rates between European and African Americans.5 While this finding has great implications for ESRD, the identification of additional risk factors for CKD, including genetic loci in association with estimated glomerular filtration rate (eGFR), may help to advance our understanding of the underpinnings of CKD in African Americans.5 In this era of identifying genetic risk factors for kidney disease, it may be appropriate to revisit one of the most common genetic disorders: sickle cell haemoglobinopathies.5In this regard, sickle cell trait (SCT), present in approximately 7–9% of African Americans, has been reported to be a potential candidate gene.6 However, conflicting reports exist as to whether SCT is a risk factor for the progression of nephropathy.6,7 Haemoglobin S (HbS) was selected for in Africa because of the protection it affords from malarial infection, a scenario similar to the protection from trypanosomal infection provided by heterozygosity for APOL1 nephropathy risk variants.6Whereas APOL1 contributes to risk for nephropathy in an autosomal recessive inheritance pattern, HbS reportedly had a dominant effect on risk, with SCT being associated with ESRD.6 In line with this finding, a few small studies on African Americans reported HbS as an independent risk factor for CKD and ESRD.8 However, other studies using a large sample of African Americans stated that SCT was not independently associated with susceptibility to ESRD in African Americans,6 highlighting the need for further studies in other populations such as those of sub-Saharan Africa where SCT is prevalent.Although SCT is very prevalent in black Africans,9 few studies have been conducted to assess the association between SCT and CKD.10 In Democratic Republic of Congo (DRC), the prevalence of CKD and SCT has been reported to be 12% and 17–24%, respectively.11-13 No study has evaluated the frequency of SCT among CKD patients to assess its association with reduced kidney function. Therefore, the aim of this clinic-based, cross-sectional study was to assess the potential association between SCT and CKD among adult Congolese patients.     

Impact of prehypertension on left ventricular mass and QT dispersion in adult black Nigerians

The heterogeneity of individuals with blood pressure (BP) < 140/90 mmHg in terms of cardiovascular (CV) risk was reported as early as 1939 by Robinson and Brucer.1 BP in the range of 120–139/80–89 mmHg (labelled then as prehypertension) was observed to be associated with high risk of progression to hypertension (HT) and cardiovascular disease (CVD) later in life when compared with BP < 120/80 mm Hg.1The term prehypertension was adopted in May 2003 by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High blood Pressure (JNC-7) to describe BP range of 120–139/80–89 mmHg.2 The resuscitation of this terminology/concept in JNC-7 was a sequel to the documentation of a higher morbidity in individuals with prehypertension in landmark publications.3-5 Prehypertension (PHT) was defined in JNC-7 not only to emphasise the excess risk associated with BP in this range, but also to focus increased clinical and public health attention on prevention.2,6,7Prevalence rates of PHT among adults in the United States, Ghana and northern Nigeria have been reported to be 31, 40 and 58.7%, respectively.7-9 In most studies, including the ones above, PHT was more prevalent than hypertension.7-9 Though PHT is associated with increased risk of major CV events independently of other CV risk factors,10 most individuals (90%) with PHT have at least one cardiovascular risk factor such as dyslipidaemia, abdominal obesity, hyperinsulinaemia, impaired fasting glucose levels, insulin resistance, a prothrombotic state, tobacco use, endothelial dysfunction, and impaired vascular distensibility.6,7,9,10QT interval dispersion (QTd) (the difference between the longest and the shortest QT intervals on a surface ECG), when excessive, is associated with increased risk of cardiovascular morbidity and mortality in population studies, and many clinical conditions, including hypertension.11,12 This has been related to ventricular electrical instability, providing the necessary substrate for lethal ventricular arrhythmias.12,13 Greater QTd and left ventricular mass have been demonstrated in hypertensive individuals compared with normal individuals.11,13,14Considering the well-established, linear relationship between BP and the risk of cardiovascular events, the CV risk associated with PHT is intermediate between normotension and hypertension.2,03 Hence, electrocardiographic and echocardiographic indices of target-organ damage in PHT may also be intermediate between normotension and hypertension. The aims of this study were: (1) to compare the QTd and indices of left ventricular hypertrophy in adult black normal and prehypertensive subjects, and (2) to evaluate the relationship of QTd with electrocardiographic and echocardiographic indices in these subjects.     

Effect of hypothermia in patients undergoing simultaneous carotid endarterectomy and coronary artery bypass graft surgery

The co-existence of coronary, carotid, peripheral and renal atherosclerotic diseases is not infrequent and it was reported that 24% of patients with coronary artery disease have at least one additional atherosclerotic lesion.1 In previous studies, 4.6 to 8.0% of patients with coronary artery disease (CAD) had severe coronary artery stenosis (CAS), the extent of the atherosclerotic involvement being significantly correlated with the carotid and coronary arteries.2,3 Simultaneous surgical management of concomitant coronary and carotid artery disease has been the focus of interest in the past two decades since success rates of coronary artery bypass grafting (CABG) has substantially increased while a preventive approach for adverse neurological outcomes has gained popularity.4 Carotid stenosis and previous history of cerebrovascular disease were reported to be among the most prominent risk factors for peri-operative stroke and neurocognitive decline in patients undergoing CABG.5The optimal decision for the timing of carotid endarterectomy (CEA) is controversial in patients submitted for CABG since data focusing on establishing the best strategy of practice are limited.6 There have been numerous cross-sectional studies reporting favourable outcomes for both simultaneous and staged CEA and CABG procedures,7-9 and some authors have suggested that the decision to perform the two procedures simultaneously should be made based on strict patient selection criteria.10 Nevertheless, delaying the CEA was found to be an independent predictor of early stroke and death in one recent randomised trial.11 This uncertainty led to an increasing trend towards individualisation of the treatment in patients with concomitant disease.Some earlier studies implied the potential role of hypothermia as a preventative measure against adverse postoperative outcomes in patients undergoing single-stage on-pump CABG and CEA.12,13 However, these studies fell short of their goal of determining whether hypothermia provides protection, because none of them involved a control group of patients undergoing CEA under normothermic conditions. In this study we sought to determine whether hypothermia provided any benefit in patients undergoing simultaneous CABG and CEA using one of two different surgical strategies.     

Short-term outcomes after hospital discharge in patients admitted with heart failure in Abeokuta,Nigeria: Data from the Abeokuta Heart Failure Registry

Heart failure (HF) has emerged as a global epidemic in at-risk populations, including those living in high-income countries and, as recently described, in low- to middle-income regions of the world, such as sub-Saharan Africa.11-4 While there are well-established HF registries to capture both the characteristics and health outcomes among those hospitalised with AHF in Europe,5,6 North America,7,8 and the Asia–Pacific region,3,9,10 there are few reports from sub-Saharan Africa.11 This includes Nigeria (the most populous country in the region), where HF has emerged as a potentially large public health problem.1Although there have been many therapeutic gains in the management of chronic HF,12 leading to improved overall survival rates,13 there has been very little parallel success (pending further evaluation of the recently reported RELAX trial14 with regard to AHF). This is particularly important when one considers the high proportion of patients who still require hospitalisation for acute HF, and associated high levels of in-patient case fatality and poor short- to medium-term health outcomes.Given the paucity of data describing health outcomes in unselected patients hospitalised with AHF in Nigeria (and indeed the wider sub-Saharan Africa), we examined short- (30 days) to medium-term outcomes (180 days) in consecutive subjects with AHF recruited into the Abeokuta HF registry over a period of six months. Standardised data collected via the registry were used to both describe the baseline characteristics of the cohort and identify correlates of mortality during the six-month follow up.     

Evaluation of left atrial mechanical function and atrial conduction abnormalities in Maras powder (smokeless tobacco) users and smokers

Tobacco use can be classified into smoking and smokeless tobacco. Smokeless tobacco is chewed or is absorbed by the nasal and oral mucosae. A type of smokeless tobacco called Maras powder (MP) is used mostly in the south-eastern region of Turkey, and in many cases users become addicted. It is obtained from a tobacco plant species known as Nicotiana rustica Linn. Nicotine concentrations in the tobacco used to produce MP are eight to 10 times higher than those in tobacco used to produce cigarettes.1 MP and its negative effects on the cardiovascular system have been well studied. MP is consumed in such a way that increase in oxidative stress is inevitable and as a result it accelerates the atherosclerotic process.2,3Cigarette smoke includes nicotine and toxic substances such as carbon monoxide and polycyclic aromatic hydrocarbons.4 Inhalation of these substances predisposes to several different atherosclerotic syndromes,5,6 and is also associated with the occurrence of cardiac arrhythmia.7,8The pathophysiological mechanism of cigarette smoking-induced cardiac arrhythmia is complicated, and the pro-fibrotic effect of nicotine on myocardial tissue with its consequent increased susceptibility to catecholamines, may play a role. Moreover, other components of cigarette smoking, such as carbon monoxide, as well as oxidative stress, are likely to cause the generation of arrhythmias. It is also known that cigarette smoking leads to cardiac autonomic dysfunction,9 and it has been implicated in prolonged QT intervals in healthy individuals.10 However, the nicotine concentration in the blood is more likely to cause the pro-arrhythmic effect of cigarette smoking.7,11 The risk of atrial and ventricular arrhythmia rises due to increased nicotine levels.9-12The prolongation of intra- and inter-atrial electromechanical intervals and the inhomogeneous propagation of sinus impulses are well-known electrophysiological characteristics of atria that are prone to fibrillation.13 Left atrial (LA) volume and LA mechanical function have recently been identified as a potential indicator of cardiac disease and arrhythmias.14,15 Prolongation of atrial electromechanical interval and impaired LA mechanical function are associated with adverse clinical events, including atrial fibrillation, stroke, diastolic dysfunction and left ventricular failure.16,17LA mechanical function and atrial conduction abnormalities have not been investigated in MP users and smokers. Therefore, our study was planned to evaluate whether MP damages intra- and inter-atrial conduction intervals and LA mechanical function as much as cigarette smoking.     

Prevalence of the metabolic syndrome and determination of optimal cut-off values of waist circumference in university employees from Angola

The metabolic syndrome is characterised by the presence of multiple metabolic risk factors for cardiovascular (CV) disease1 and type 2 diabetes mellitus.2 In clinical practice, the metabolic syndrome is diagnosed by combinations of three or more of the following five risk factors: central obesity, elevated blood pressure, glucose intolerance, hypertriglyceridaemia and low high-density lipoprotein cholesterol (HDL-C).3-6Worldwide the prevalence of the metabolic syndrome is increasing and becoming a pandemic, and this increase has been mainly attributed to sedentary lifestyle and obesity.7 However, levels of prevalence may vary greatly according to cut-off points of diagnostic criteria and the ethnic group studied.8In sub-Saharan Africa, the majority of countries are experiencing a rapid demographic and epidemiological transition.9,10 Available information from studies in African populations reported a prevalence of the metabolic syndrome ranging from 0% to as high as about 50% or more, depending on the population setting.11 These data however, are limited to some countries,12-21 since there are no available data for the majority of African countries.Angola is a country in sub-Saharan Africa, which in the last few years has undergone significant political changes, accompanied by a rapid economic growth and increased urbanisation. These changes may imply an increasing prevalence of factors contributing to the metabolic syndrome, such as obesity, insufficient physical activity, dyslipidaemia, high blood pressure and glucose intolerance. However, the prevalence of the metabolic syndrome and which factors contribution more to its occurrence in the Angolan population remain unknown.Despite the efforts of several organisations to regulate the algorithm for a definition of the metabolic syndrome,3-5 there is inconsistency on cut-off levels of waist circumference (WC) for defining the metabolic syndrome in several populations. The International Diabetes Federation (IDF)5 recommended the use of ethnic or country-specific cut-off values of WC for the majority of populations, a recommendation reinforced in the Joint Interim Statement (JIS),7 which tried to define different criteria for a definition of the metabolic syndrome.These cut-off values were defined using different methods. For example, Western countries derived their cut-off values of WC from a correlation with body mass index (BMI),4,22 whereas Asian groups tried to define WC cut-off values yielded by receiver operating characteristics (ROC) curve analyses.23 Due to a lack of specific data from African populations, cut-off points of WC derived from the European population have been recommended,5,7 although emerging data suggest that African-specific cut-off values would be different from the European cut-off points currently recommended by the IDF.18,24,25 Therefore, definition of a more reliable cut-off point for WC is needed to build a consistent tool for diagnosis of the metabolic syndrome in sub-Saharan African populations.The aim of this study was to determine the prevalence of the metabolic syndrome in a sample of Africans from Angola, using either the third report of the National Cholesterol Education Program Adult Treatment Panel (ATP III)4 or the JIS7 criteria. Additionally, this study tried to identify threshold WC levels that best predict other components of the metabolic syndrome.     

Analysis of clinical outcomes of intra-aortic balloon pump during coronary artery bypass surgery

An intra-aortic balloon pump (IABP) increases coronary blood flow and reduces left ventricular afterload.1-3 It helps to increase the necessary amount of time for heart recovery in low cardiac output syndrome following a cardiopulmonary bypass (CPB) or ischaemic events. In earlier reports, researchers had suggested that postoperative heart failure was the single indication for IABP support.1,2 However, these indications have widened, and the use of IABP support has recently become more common.Frequently reported complications of IABP include bleeding, aorto-iliac injury and thrombocytopenia.4,5 In-hospital mortality and early mortality of patients requiring IABP support is high, ranging from 26 to 50%, due to the cardiac problems that initially led to the need for this support.6,7The elderly population is continuously increasing across the globe. Parallel with this increase, the number of older patients being referred for coronary artery bypass grafting (CABG) has also increased.8 Although several studies have shown a significant increase in surgical mortality of elderly patients,9 there have been no studies regarding clinical outcomes of IABP in elderly patients.In the present study, we aimed to analyse and compare older with younger patients, regarding clinical features, postoperative complications, intensive care unit and hospital stays, and morbidity and mortality rates in patients who had undergone CABG surgery and required IABP support.     

Prevalence and risk factors for hypertension and association with ethnicity in Nigeria: results from a national survey

Hypertension is increasingly being recognised as an important public health problem in sub-Saharan Africa, with 26.9% of men and 28.4% of women in 2000 being estimated to have hypertension.1 Although lower than the prevalence in high-income countries (37.4% in men and 37.2% in women), in terms of numbers of people affected, the burden of hypertension in low- and middle-income countries is greater due to the large population.1Hypertension has been recognised as a strong independent risk factor for heart disease and stroke and a predictor of premature death and disability from cardiovascular complications.2 It has been reported that 13.5% of deaths and 6% of disability-adjusted life years (DALYs) were attributed to hypertension globally, and for low- and middle income people, these figures were 12.9 and 5.6%, respectively over the period 1990 to 2001.3 Although infectious diseases remain the leading cause of mortality and morbidity in sub-Saharan Africa, the prevalence of cardiovascular disease and hypertension is rising rapidly.4It has been emphasised that urbanisation is a key reason for the increasing rates of hypertension, as evidenced by the higher prevalence of hypertension in urban areas.4-6 Urban lifestyles, characterised by sedentary living, increased salt intake, obesity and stress contribute to these differences.5 With the urban population in sub-Saharan Africa projected to increase, a greater risk of hypertension is anticipated.Studies on the association between ethnicity and hypertension in high-income countries have documented a higher prevalence of hypertension in black ethnic groups compared to white ethnic groups.7-9 Reasons for this association are complex, unclear and much debated, reflecting genetic and biochemical mechanisms, and environmental and socio-economic factors.10,11 There is limited evidence regarding differences in the prevalence of hypertension between ethnic groups within the broader classification of black ethnicity.6,12,13Studies in Nigeria and sub-Saharan Africa have mainly involved specific geographical areas or have focused on sub-groups of the population.5,14 Surveys from Nigeria report prevalence estimates ranging from 20.2 to 36.6%, but all have involved participants with different age ranges.15-18 To plan services for hypertension in Nigeria, it is essential to have accurate prevalence estimates for the whole population and to identify populations at risk.Nigeria, which is the most populous country in sub-Saharan Africa, is home to over 250 different ethnic groups. Nigeria is experiencing rapid urbanisation of the population, which is likely to increase the population at risk for hypertension.19 The present study is one of the largest population-based surveys in the region and is able to provide a nationally representative estimate of hypertension for Nigeria.     

In vitro effects of sodium nitroprusside and leptin on norepinephrine-induced vasoconstriction in human internal mammary artery

Coronary heart disease (CHD) and stroke are the largest contributors to global mortality in low-, middle- and high-income countries as a result of current lifestyles. They will continue to cause decreased quality of life and contribute to the causes of morbidity and mortality throughout the world.1,2CHD, also known as coronary artery disease, is the narrowing of coronary arteries, hampering blood and oxygen supply to the heart when plaque builds up in the arteries. The heart is an aerobic organ and disruption of its normal oxygen supply causes irreversible changes in heart tissue. If the disruption of oxygen supply is severe, this becomes life threatening.3Although CHD cannot be cured, there are several treatment options to relieve the symptoms and reduce the progression and risk of complications (heart attack), and thereby prolong the expected lifespan. Treatment options include lifestyle changes and medication, but depending on the severity of the disease, more aggressive treatment methods including interventional procedures (angioplasty and stenting) or coronary artery bypass surgery are warranted.4Revascularisation by coronary artery bypass graft (CABG) surgery is a process of restoring the blood flow around existing blockages to the heart using autologous bypass grafts (or artificial grafts). The immediate success of this procedure is related to surgical technique and the anatomical characteristics of the grafted coronary artery.5 After grafting, the vascular smooth muscle cells of the new vessels are the primary regulators of vascular tone. Therefore characterisation of the contractile and relaxatory profiles of the commonly used graft vessels in response to major coronary vasodiladator and vasoconstrictor agents has been carried out in in vitro pharmacological investigations.The effects of noradrenaline, dopamine,6 adenosine and nitric oxide7,8 are well established, but other endogenous agents9 that increase in concentration in the circulation during cardiovascular disease are poorly studied. Leptin is a hormone secreted mostly from adipocytes, which is also produced in small amounts from other human tissues such as the heart, stomach, placenta and mammary epithelium.10-14 In addition to its essential roles in feeding behaviour and energy balance,11,12 leptin also plays an important role in many different peripheral processes, including haematopoietic, nociception, reproduction, immunity, wound healing, bone remodelling and cognitive functions.13The internal mammary artery (IMA) is the most commonly used vessel in coronary artery grafting to bypass stenosed coronary arteries. Morever its patency rate is longer lasting than the saphenous vein (SV). The IMA has a dynamic vascular bed therefore several vasoactive substances may cause contractile or dilatory responses in the IMA.Protein kinase C (PKC) is a family of serine/threonine protein kinases. It plays a critical role in the pathogenesis of many heart diseases.15-17Although it has been documented that leptin has a vasodilatatory effect,18,19 the cellular mechanism of this effect is not well documented. The aim of this study was to investigate the possible involvement of PKC-mediated mechanism(s) in the vasorelaxatory effects of sodium nitroprusside (SNP) and leptin on norepinephrine pre-contracted excised human IMA.     

Comparison of one- and two-stage basilic vein transposition for arterio-venous fistula formation in haemodialysis patients: preliminary results

In recent years, the number of patients requiring haemodialysis (HD) has been rapidly increasing globally, including Turkey. Arterio-venous fistula (AVF) is the most frequently used method in patients with end-stage renal failure (ESRF) for HD.1The Kidney Disease Outcome Quality Initiative (KDOQI) recommends autologous radio-cephalic or brachio-cephalic AVF as a primary method of choice in HD patients, and basilic vein transposition (BVT) as a secondary option.2,3 In 1976, Dagher et al.4 first described the technique of BVT for HD. In later years, several techniques were used.5-11 This study aimed to compare the patency and complication rates of AVF formed by one-stage and two-stage BVT.     

Prevalence of hypertension in the Gambia and Sierra Leone,western Africa: a cross-sectional study

Hypertension (HTN) is a chronic, slowly progressive disease affecting about one billion people globally and leading to about 7.1 million deaths annually. People of African origin may be particularly susceptible to hypertension.1-3 Defined as a sustained systolic blood pressure (SBP) above 140 mmHg, a diastolic blood pressure (DBP) above 90 mmHg or both, the aetiology of HTN can be classified as primary or secondary. While there is no known cause for primary (essential) HTN, which accounts for 90–95% of cases, the remaining 5–10% of cases is defined as secondary HTN and is caused by other disease conditions, which may affect the renal, circulatory, endocrine or other organ systems.Many factors are associated with, and may contribute to the development and persistence of primary HTN, including obesity, stress, smoking,4 low potassium intake, high sodium (salt) and alcohol intake,5,6 familial and genetic influences,7,8 and low birth weight.9 On the other hand, hyperthyroidism, hypothyroidism and other conditions causing hormonal changes may be associated with primary pulmonary HTN.10,11 Regardless of the cause, the consequences of HTN include renal failure, heart failure, myocardial infarction, pulmonary oedema and stroke.12Given these undesirable outcomes, treatment and prevention have assumed increasing emphasis in the management of HTN. Modification of risk factors can be achieved by reducing body weight and decreasing sugar intake, along with lowering alcohol consumption,13,14 as well as reducing salt intake and increasing potassium intake.15,16 Secondary HTN is managed by treating the underlying cause. Drugs available for the treatment of HTN, whether primary or secondary, include calcium-channel blockers (CCB), angiotensin converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), diuretics, α-blockers and β-blockers.Race and ethnicity may influence pathogenesis, prevalence and treatment of HTN,17 perhaps through genetic influences. As a consequence, HTN remains one of the most common CVDs in Africa and one of the most frequent causes of death in the sub-Saharan African region.18,19 In 2000, the rate of HTN in sub-Saharan Africa was reported to be 26.9% in males and 28.3% in females.20 Low socio-economic status (SES) may additionally play an important role in the high prevalence of HTN in western and sub-Saharan Africa.A cross-sectional survey in Tanzania revealed that treatment rates for HTN were very low, especially among people with low SES.21 Low SES led to inadequate education levels as a factor correlating with a higher blood pressure (BP) in adults and resulted in a low treatment rate for HTN due to monetary issues.22Stress, in addition, was another factor related to HTN prevalence, especially in Africa.23 It has been shown that psychosocial stress affects the L-arginine/nitric oxide (NO) system, with a higher susceptibility in black Africans, which in turn contributes to a higher risk of CVD in those individuals.24Therefore, a multiplicity of factors may be associated with and contributing to a high prevalence of HTN among Africans. The current study was undertaken to determine and quantitate the prevalence of HTN in two countries in western sub-Saharan Africa, namely, the Gambia and Sierra Leone.     

Epidemiological African day for evaluation of patients at risk of venous thrombosis in acute hospital care settings

Acute venous thromboembolism (VTE) is a complication in patients hospitalised for a wide variety of acute medical and surgical conditions.1,2 In developed countries, VTE is the most common preventable cause of death among hospitalised patients. Over the last 30 years, extensive research has demonstrated a high risk of VTE in patients who undergo major surgery or experience severe trauma. Patients hospitalised for acute medical illness have approximately the same level of VTE risk as patients who undergo major general surgery.3-5The benefits of VTE prophylaxis are similar for both medical and moderate-risk surgical patients.6,7 VTE prophylaxis is substantially underused. There is great variation in the use of prophylaxis between countries. Even when prophylaxis is used, it may be used sub-optimally.8-10 Although some surveys and studies suggest that physicians have begun to recognise VTE as a serious health problem and use prophylaxis for at least some high-risk patients, a number of recent studies demonstrate that VTE prophylaxis remains underutilised.11-20     

The protective effect of topical rifamycin treatment against sternal wound infection in diabetic patients undergoing on-pump coronary artery bypass graft surgery

Sternal wound infection (SWI) is a rare complication occurring after coronary artery bypass graft (CABG) surgery. Sternal wound infection occurs in one to 3% of patients and has a mortality rate of up to 40%. It is also associated with prolonged hospital stay and increased healthcare costs.1-4According to the American College of Cardiology/American Heart Association (ACC/AHA) 2004 guideline update for CABG surgery, the risk of mediastinitis is evaluated before CABG surgery using factors, such as age of patient, the presence of obesity, diabetes or chronic obstructive pulmonary disease (COPD), the need for dialysis, an ejection fraction (EF) < 40%, and being scheduled for emergency surgery.5In studies by Khanlari et al. and Kloos et al., patients with SWI were divided into two subgroups: superficial sternal wound infection (SSWI) and deep sternal wound infection (DSWI).6,7 While SSWI involves only subcutaneous tissue, DSWI is associated with sternal osteomyelitis and sometimes with infected retrosternal space (termed mediastinitis). These researchers reported that DSWI occurred in 0.25 to 2.3% of patients.6,7Rifamycin SV is a relatively effective agent for the treatment of gram-positive bacteria, Mycobacterium tuberculosis and certain gram-negative bacteria. Rifampicin, derived from rifamycin SV, is readily absorbed after oral administration and possesses higher antimicrobial activity against Staphylococcus aureus S epidermidis, Streptococcus viridans, and Mycobacterium tuberculosis, even in very low doses. In only one study in the literature has the use of antibiotics containing rifampicin been suggested to improve outcomes in staphylococcal deep-wound infections.6In the present study, we aimed to investigate the protective effects of topical rifamycin SV treatment on SWI after on-pump CABG surgery in diabetic patients.     

Hypertensive retinopathy and its association with cardiovascular,renal and cerebrovascular morbidity in Congolese patients

Hypertension is a major public health problem worldwide and on the African continent.1,2 The disease, once considered to be rare outside Europe and North America, is now a leading cause of disability and mortality in developing countries. Its prevalence is projected to reach 30% worldwide by 2025.2Poor control of hypertension increases the likelihood of complications affecting the cardiovascular and cerebrovascular systems, kidney and retina, often labelled under the term target-organ damage (TOD).1 The development of subclinical TOD, such as left ventricular hypertrophy (LVH), increased intima–media thickness of the large vessels, microalbuminuria following glomerular dysfunction, cognitive decline and hypertensive retinopathy precedes the occurrence of major complications, which include stroke, congestive heart failure and myocardial infarction, renal failure and retinal vascular occlusions.3-5 In the Democratic Republic of Congo (DRC), the prevalence of systemic hypertension has been reported to be over 25%,6,7 whereas hypertension and associated complications account for over 20% of deaths among adults.8Studies have demonstrated that TOD increases cardiovascular risks over that already associated with elevated blood pressure alone. For example, it has been shown that once LVH has developed following long-standing systemic hypertension, it behaves as an independent risk factor and a predictor of both further cardiac complications,9 and other incident vascular events such as ischemic stroke and myocardial infarction.10 Similarly, the presence of cerebrovascular and renal damage may raise cardiovascular risk over that conferred by hypertension itself.11,12In addition, hypertensive retinopathy has long been known as a predictor of systemic morbidity and mortality. Both epidemiological and clinical studies have provided evidence that markers of hypertensive retinopathy are associated with raised blood pressure, systemic vascular diseases, and subclinical cerebrovascular and cardiovascular disease, and predict incident clinical stroke, congestive heart failure and mortality due to cardiovascular complications.13 This association of hypertensive retinopathy with other TOD has also been shown to be independent of blood pressure and other risk factors, which supports the recommendation that retinal vascular changes should be assessed in individuals with systemic hypertension for better extra-ocular TOD risk stratification.13While the number of reports on hypertensive TOD has been on the rise on the African continent, the relationship between hypertensive retinopathy and other TOD has largely remained unexplored. The aim of this study was to examine the association of hypertensive retinopathy with LVH, chronic kidney disease (CKD) and stroke in Congolese patients.