Cardiomyopathies and myocardial disorders in Africa: present status and the way forward.

A review of heart diseases in Africa shows that the cardiomyopathies continue to be important causes of morbidity and mortality in the population. Hypertension remains the commonest cause of myocardial disease, followed by the cardiomyopathies. Ischaemic heart disease continues to be rare. Of the cardiomyopathies, dilated cardiomyopathy (DCM) is still the commonest. A large proportion of patients diagnosed with DCM in Africa have been shown to be cases of hypertensive heart failure, with varying degrees of myocardial dysfunction. Hypertrophic cardiomyopathy, which in the past was thought to be rare among Africans, has been shown to have the same prevalence as in other parts of the world. Moreover it is now known to be a genetic disorder. Endomyocardial fibrosis has become rare in communities where it used to be common. Its aetiology continues to be elusive. Arrhythmogenic right ventricular cardiomyopathy has been reported among Africans but there are no reports of left ventricular non-compaction or the ion channelopathies from Africa. Lenegre disease and the long-QT syndromes are well-known entities in clinical practice in Africa although long-QT in Africa is associated with potassium deficiency arising from prolonged treatment with diuretics. Left ventricular non-ischaemic aneurysms still occur but are rare. In view of these, a new classification of myocardial disorders was proposed for Africa.

Target-organ damage and cardiovascular complications in hypertensive Nigerian Yoruba adults: a cross-sectional study.

BACKGROUND: Hypertension is a major challenge to public health as it is frequently associated with sudden death due to the silent nature of the condition. By the time of diagnosis, some patients would have developed target-organ damage (TOD) and associated clinical conditions (ACC) due to low levels of detection, treatment and control. TOD and ACC are easy to evaluate in a primary healthcare (PHC) setting and offer valuable information for stratifying cardiovascular risks in the patient. The aim of this study was to evaluate the prevalence and correlates of TOD and established cardiovascular disease (CVD) in hypertensive Nigerian adults. METHODS: A cross-sectional study was conducted on 2 000 healthy Yoruba adults between 18 and 64 years who lived in a rural community in south-western Nigeria. Participants diagnosed to have hypertension were examined for TOD and ACC by the presence of electrocardiographically determined left ventricular hypertrophy (LVH), microalbuminuria or proteinuria, retinopathy, or history of myocardial infarction and stroke. RESULTS: A total of 415 hypertensive participants were examined and of these, 179 (43.1%) had evidence of TOD and 45 (10.8%) had established CVD. TOD was associated with significantly higher systolic (SBP) and diastolic blood pressure (DBP). The prevalence of LVH was 27.9%, atrial fibrillation 16.4%, microalbuminuria 12.3%, proteinuria 15.2%, hypertensive retinopathy 2.2%, stroke 6.3%, congestive heart failure (CHF) 4.6%, ischaemic heart disease 1.7%, and peripheral vascular disease 3.6%. Compared with those with normal blood pressure (BP), the multivariate adjusted odds ratios (95% confidence interval) of developing TOD was 3.61 (0.59-8.73) for those with newly diagnosed hypertension; 4.76 (1.30-13.06) for those with BP ≥ 180/110 mmHg; and 1.85 (0.74-8.59) for those with diabetes mellitus. CONCLUSIONS: This study provides new data on TOD and its correlates in a nationally representative sample of hypertensive adults in Nigeria. In this low-resource setting, attempts should be made to detect hypertensive patients early within the community and manage them appropriately before irreversible organ damage and complications set in. The methods used in this study are simple and adaptable at the primary healthcare level for planning prevention and intervention programmes.

Early diastolic functional abnormalities in normotensive offspring of Nigerian hypertensives.

BACKGROUND: Some studies have suggested that diastolic dysfunction precedes the clinical manifestation of hypertension. Whether changes in cardiac structure and function predate the clinical manifestation of hypertension later in life is now being investigated. The aim of this study was to assess the differences in cardiac structure and function between the offspring of hypertensive and normotensive parents. METHODS: Eighty normotensive offspring of hypertensive parents (OHyp) (41 females and 39 males) and 62 normotensive offspring of normotensive parents (ONorm) (31 males and 31 females) were recruited for echocardiography. RESULTS: The mean age was 25.0 (5.31) and 24.3 (3.60) years in the OHyp and ONorm participants, respectively (p = 0.369). Other baseline parameters were comparable between the two groups. Septal wall thickness in systole was higher in the OHyp than the ONorm subjects [1.3 (0.35) vs 1.1 (0.25), p = 0.0173]. Indexed left ventricular mass [28.1 (7.33) vs 27.5 (7.23), p = 0.631] and relative wall thickness [(0.3 (0.10) vs 0.3 (0.90), p = 0.280] were similar in the two groups. The offspring of hypertensives had lower deceleration time [149.9 (38.89) vs 169.0 (50.08) ms, p = 0.012], prolonged duration of pulmonary A reverse flow [113.5 (70.69) vs 81.7 (38.31) ms, p = 0.024], increased myocardial isovolumic relaxation time [173.4 (47.98) vs 156.1 (46.74) ms, p = 0.033] and a lower myocardial Em [0.2 (0.05) vs 0.3 (1.38), p = 0.037] and myocardial Em/Am ratio [1.6 (0.01) vs 2.1 (0.01), p = 0.019] than the offspring of normotensives. CONCLUSION: This study showed that offspring of OHyp subjects had early diastolic functional abnormalities when compared with offspring of ONorm participants. Longitudinal studies are needed to determine the implications of this finding in this African population.

Prevalence of asymptomatic left ventricular systolic dysfunction in hypertensive Nigerians: echocardiographic study of 832 subjects.

BACKGROUND: We sought to determine the prevalence of echocardiographically determined left ventricular systolic dysfunction in asymptomatic hypertensive subjects seen in Abeokuta, Nigeria. METHODS: Echocardiography was performed in 832 consecutive hypertensive subjects referred for cardiac evaluation over a three-year period. RESULTS: Data were obtained in 832 subjects (50.1% women) aged 56.0 ± 12.7 years (men 56.9 ± 13.3 years, women 55.0 ± 12.0 years, range 15-88). The prevalence of left ventricular systolic dysfunction (LVSD) was 18.1% in the study population (mild LVSD = 9.6%, moderate LVSD = 3.7% and severe LVSD = 4.8%). In a multivariate analysis, male gender, body mass index and LV mass were the predictors of LVSD. CONCLUSION: Significant numbers of hypertensive subjects in this study had varying degrees of left ventricular systolic dysfunction. Early introduction of disease-modifying drugs in these patients, such as angiotensin converting enzyme inhibitors or angiotensin receptor blockers may retard or prevent the progression to overt heart failure.

A prevalence of cardiometabolic risk factors among a rural Yoruba south-western Nigerian population: a population-based survey.

BACKGROUND: It has been hypothesised that rural sub-Saharan Africa is at an early stage of epidemiological transition from communicable to non-communicable diseases (NCD). Limited information exists about the prevalence of cardiometabolic risk factors and the burden of cardiovascular disease (CVD) in the adult Nigerian population, especially in the rural setting. OBJECTIVES: The aim of this study was to assess and describe the prevalence of several cardiometabolic risk factors in the sub-Saharan adult population of a rural Yoruba community, living in south-western Nigeria. METHODS: The study was a descriptive, cross-sectional, random-sample survey. Participants were visited at home by trained nurses and community health extension workers (CHEW) who administered a questionnaire, took the relevant history, carried out clinical examinations and measurements and took samples for laboratory tests. They were supervised by primary healthcare physicians serving the community. The variables recorded comprised clinical history, CVD risk factors including blood pressure (BP), body mass index (BMI), waist circumference, blood sugar and serum lipid levels, cigarette use, and dietary habits. The participants included 2 000 healthy adults aged 18 to 64 years who had been living in the area for more than three years. RESULTS: The average age was 42.1 +/- 21.6, with 43.7% (873) being males and 56.3% (1127) females; 20.8% were hypertensive with BP > or = 140/90 mmHg, 42.3% of the men and 36.8% of the women had BP > or = 130/85 mmHg; 2.5% had diabetes, 1.9% had hypertriglycerideaemia, 43.1% had low HDL-C, 3.9% had general obesity, 14.7% had abdominal obesity, 3.2% were physically inactive, and 1.7% smoked cigarettes. Overall, 12.9% of the subjects were found to have at least one CVD risk factor. Using the Adult Treatment Panel (ATP) III criteria, 2.1% of men and 2.7% of women in the study population had at least three of the criteria, the commonest being HDL-C < 40 mg/dl in men or < 50 mg/dl in women, followed by BP >or = 130/85 mmHg, then waist circumference > 88 cm in women or > 102 cm in men, followed by blood glucose > or = 110 mg/dl. CONCLUSION: The results obtained from this study strongly suggest a high prevalence of cardiometabolic risk factors in this rural population and that the epidemiological transition is not restricted to the urban population. This serves as a wake-up call for action in the planning of health services for the management of CVD and other chronic NCDs.

Pattern of heart failure in Abuja, Nigeria: an echocardiographic study.

AIM: Despite heart failure having been identified in subjects in sub-Saharan Africa over the last 60 years, there is still a dearth of data, especially echocardiographic data on heart failure. We therefore set out to analyse the clinical and echocardiographic features of all consecutive subjects presenting with heart failure in a tertiary institution in Nigeria. METHODS: Three hundred and forty subjects with heart failure, according to the guidelines of the European Society of Cardiology, were studied. Each patient had two-dimensional guided transthoracic echocardiography. RESULTS: The mean age of the patients was 50.60 +/- 15.29 years, and 50.9% of the study population were males while 49.1% were females. The commonest cause of heart failure identified was hypertension in 61.5% of the patients; 75.5% had systolic heart failure, whereas 23.5% had heart failure with preserved ejection fraction. CONCLUSIONS: Untreated hypertension has been identified as the leading cause of heart failure in Abuja, Nigeria, which is similar to that in many other parts of sub-Saharan Africa. Coronary artery disease is a rare cause of heart failure in this population group.

Audit of Echocardiographic Services at the University College Hospital Ibadan.

BACKGROUND: Echocardiography is useful in the diagnosis of cardiovascular diseases and it influences management. It is becoming widely available in our Teaching Hospitals though expensive. It is therefore important to know the value of echocardiography in patients' diagnosis. METHODS: One thousand five hundred and forty four patients referred for transthoracic echocardiography over 19-month period (March 2003 to September 2004) were studied. M mode, two dimensional and Doppler studies were out using ALOKA SSD 1700. RESULTS: One thousand five hundred and forty four patients (778 males and 766 females) had echocardiography. Mean age was 51.4 +/- 15.5. Minimal age was 15 years while maximum was 100 years. The commonest indication for echocardiography include Hypertension 727 (47.1%), Pre-Chemotherapy assessment 127 (8.2%), Heart failure 117 (7.6%) and Routine Medical Check Up 99 (6.4%). The highest source of referral came from Cardiology unit 746 (48.3%). Staff Clinic 128 (8.3%), Surgery 127 (8.2%) and Nephrology 88 (5.7%). Six hundred and eighty seven (44.6%) were diagnosed as Hypertensive Heart Disease, 674 (36.5%) were Normal Study and 54 (3.5%) had Valvular Heart Disease. CONCLUSION: The study showed the different indications for echocardiography, source of referral and diagnosis. There is an emerging need for echocardiography in our patients so as to improve their management.

Electrocardiographic left ventricular hypertrophy with strain pattern: prevalence, mechanisms and prognostic implications.

BACKGROUND: Electrocardiographic left ventricular hypertrophy with strain pattern has been documented as a marker for left ventricular hypertrophy. Its presence on the ECG of hypertensive patients is associated with a poor prognosis. This review was undertaken to report the prevalence, mechanism and prognostic implications of this ECG abnormality. MATERIALS AND METHODS: We conducted a comprehensive search of electronic databases to identify studies relating to the title of this review. The search criteria were related to the title. Two of the reviewers independently screened the searches. RESULTS: Results were described qualitatively. The data were not pooled because there were no randomised studies on the topic. The prevalence of ECG strain pattern ranged from 2.1 to 36%. The highest prevalence was reported before the era of good antihypertensive therapy. The sensitivity as a measure of left ventricular hypertrophy ranged from 3.8 to 50%, while the specificity was in the range of 89.8 to 100%. Strain pattern was associated with adverse cardiovascular risk factors as well as increased all-cause and CV morbidity and mortality. ST-segment depression and T-wave inversion on the ECG was recognised as the strongest marker of morbidity and mortality when ECG-LVH criteria were utilised for risk stratification in hypertensive subjects. CONCLUSION: Electrocardiographic strain pattern identifies cardiac patients at higher risk of cardiovascular-related as well as all-cause morbidity and mortality.

Electrocardiographic Left Ventricular Hypertrophy with Strain Pattern : Prevalence; Mechanisms and Prognostic Implications : Review Article

Background: Electrocardiographic left ventricular hypertrophy with strain pattern has been documented as a marker for left ventricular hypertrophy. Its presence on the ECG of hypertensive patients is associated with a poor prognosis. This review was undertaken to report the prevalence; mechanism and prognostic implications of this ECG abnormality. Materials and methods: We conducted a comprehensive search of electronic databases to identify studies relating to the title of this review. The search criteria were related to the title. Two of the reviewers independently screened the searches. Results: Results were described qualitatively. The data were not pooled because there were no randomised studies on the topic. The prevalence of ECG strain pattern ranged from 2.1 to 36. The highest prevalence was reported before the era of good antihypertensive therapy. The sensitivity as a measure of left ventricular hypertrophy ranged from 3.8 to 50; while the specificity was in the range of 89.8 to 100. Strain pattern was associated with adverse cardiovascular risk factors as well as increased all-cause and CV morbidity and mortality. ST-segment depression and T-wave inversion on the ECG was recognised as the strongest marker of morbidity and mortality when ECG-LVH criteria were utilised for risk stratification in hypertensive subjects. Conclusion: Electrocardiographic strain pattern identifies cardiac patients at higher risk of cardiovascular-related as well as all-cause morbidity and mortality

Comparison of Araoye's criteria with standard electrocardiographic criteria for diagnosis of left ventricular hypertrophy in Nigerian hypertensives.

BACKGROUND: Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular morbidity and mortality. Various electrocardiographic (ECG) criteria for LHV give poorer performance in black subjects when compared with white subjects. Araoye proposed a code system for improved ECG diagnosis of LVH in blacks. The Araoye's criteria are yet to be validated in black subjects. STUDY DESIGN: Electrocardiograms and echocardiograms were obtained from 100 hypertensive subjects and 60 controls. ECG LVH was determined by the Araoye's code criteria, Sokolow-Lyon; Cornell voltage; and Romhilt-Estes point score. Echocardiographic LVH was defined by LV mass indexed for height at 97.5 percentile of the controls (126 g.m(-1) and 130 g.m(-1) in females and males respectively). RESULTS: The prevalence of echocardiographic LVH indexed for height was 34% and 1.67% in the hypertensive and controls respectively while the prevalence of electrocardiographic LVH among the hypertensives were 18% by Romhilt Estes score, 48% by Sokolow-Lyon's criteria, 22% by Cornell's criteria and 51% by Araoye's criteria. The sensitivity and specificity respectively of the various electrocardiographic criteria were 65.7% and 76.8% for Sokolow-Lyon, 25.7% and 88.8% for Cornell's criteria 25.7% and 92.8% for Romhilt-Estes score and 71.4% and 74.4% for Araoye's criteria. Araoye's criteria did not differ significantly from Sokolow-Lyon criteria in identifying LVH but differed significantly from Cornell and Romhilt-Estes criteria. The number of positive codes in Araoye's criteria was significantly associated with the blood pressures, LV dimensions, and LV mass. CONCLUSION: The Araoye's code system for electrocardiographic diagnosis of LVH offer no comparative advantage over Sokolow-Lyon's criteria. However, the number of positive codes in Araoye's criteria identifies those individuals with more severe LVH.

Association between electrocardiographic left ventricular hypertrophy with strain pattern and left ventricular structure and function.

BACKGROUND AND PURPOSE: Electrocardiographic left ventricular hypertrophy (LVH) with strain pattern has been documented as a marker for LVH. Its presence on the ECG of hypertensive patients is associated with poor prognosis. The study was carried out to assess the association of the electrocardiographic strain with left ventricular mass (LVM) and function in hypertensive Nigerians. MATERIAL AND METHODS: ECG as well as echocardiograms were performed in 64 hypertensive patients with ECG-LVH and strain pattern, 65 patients with ECG-LVH by Sokolow-Lyon (SL) voltage criteria and 62 normal controls. RESULTS: The study showed that electrocardiographic left ventricular (LV) strain pattern is associated with dilated left atrium, larger LV internal dimensions and greater absolute and indexed LVM in hypertensive Nigerians compared with ECG-LVH by SL voltage criteria alone or normal controls. CONCLUSION: The findings of this study support the fact that the ECG strain pattern is associated with increased LVM and an increased risk of developing abnormal LV geometry.

Comparison of Araoye's criteria with standard electrocardiographic criteria for diagnosis of left ventricular hypertrophy in Nigerian hypertensives

Background: Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular morbidity and mortality. Various electrocardiographic (ECG) criteria for LHV give poorer performance in black subjects when compared with white subjects. Araoye proposed a code system for improved ECG diagnosis of LVH in blacks. The Araoye's criteria are yet to be validated in black subjects.Study design: Electrocardiograms and echocardiograms were obtained from 100 hypertensive subjects and 60 controls. ECG LVH was determined by the Araoye's code criteria; Sokolow-Lyon; Cornell voltage; and Romhilt-Estes point score. Echocardiographic LVH was defined by LV mass indexed for height at 97.5 percentile of the controls (126g.m-1 and 130g.m-1 in females and males respectively). Results: The prevalence of echocardiographic LVH indexed for height was 34and 1.67in the hypertensive and controls respectively while the prevalence of electrocardiographic LVH among the hypertensives were 18by Romhilt Estes score; 48by Sokolow-Lyon's criteria; 22by Cornell's criteria and 51by Araoye's criteria. The sensitivity and specificity respectively of the various electrocardiographic criteria were 65.7and 76.8for Sokolow-Lyon; 25.7and 88.8for Cornell's criteria 25.7and 92.8for Romhilt-Estes score and 71.4and 74.4for Araoye's criteria. Araoye's criteria did not differ significantly from Sokolow-Lyon criteria in identifying LVH but differed significantly from Cornell and Romhilt-Estes criteria. The number of positive codes in Araoye's criteria was significantly associated with the blood pressures; LV dimensions; and LV mass. Conclusion: The Araoye's code system for electrocardiographic diagnosis of LVH offer no comparative advantage over Sokolow-Lyon's criteria. However; the number of positive codes in Araoye's criteria identifies those individuals with more severe LVH

Prevalence of mitral valve prolapse in healthy adult Nigerians as diagnosed by echocardiography.

Fifty (male = 24; female = 26; age 49.33 +/- 12.16) presumably healthy adult Nigerians were prospectively examined for the presence of mitral valve prolapse (MVP). We performed clinical, electrocardiographic (ECG), M-mode echocardiographic (M-mode echo) and two-dimensional echocardiographic (2-D echo) examinations on these subjects. 2-D echos were obtained from parasternal and apical acoustic windows. Parasternal long axis view obtained when the transducer was perpendicular to the chest wall with both mitral valve leaflets and left atrium recorded was considered optimal for studying mitral valve systolic motion. MVP was defined as late or holosystolic bowing of mitral valve leaflet at least 2 mm or 3 mm, respectively, below the C-D line at M-mode echo; or, marked systolic extension of one or both mitral valve leaflets cephalad to the plane of mitral annulus into the left atrium. No subject had classical features of Marfan's Syndrome. Of the four subjects with cardiac symptoms, only one had diagnostic MVP. Three subjects had mid-to late systolic click following valsalva manouver. Seven subjects had apical late systolic murmur none of which was louder than grade II/VI. Four of them had combined anterior and posterior leaflet prolapse and one had posterior leaflet prolapse compatible with diagnostic MVP, thus resulting in 10% prevalence rate of MVP in the study population. Two other subjects with late systolic murmur had no echocardiographic evidence of MVP. Three subjects with non-diagnostic mild-to moderate prolapse of the anterior leaflet alone on 2-D echo had no clinical murmur even though two of them complained of palpitations. Seven otherwise normal subjects had holosystolic bowing of mitral valve leaflets on M-mode echo but not on 2-D echo and were thus classified into non-diagnostic MVP group. No subject with MVP had serious arrhythmias on resting ECG. These results indicate that the prevalence of MVP in presumably healthy adult Nigerians was 10%. The use of M-mode echo resulted in over-diagnosis, whereas 2-D echo was more accurate in identifying true anatomical and structural abnormalities of the mitral valve.

Congestive heart failure and ventricular arrhythmias in relation to serum magnesium.

Congestive Heart Failure (CHF) is associated with biochemical evidence of electrolyte imbalance including magnesium deficit, which may increase myocardial electrical instability, risk of malignant arrhythmias and sudden death. The aim of this study was to determine serum magnesium concentration in 45 patients (Group I; 24 male, 21 female; the average age 49.7 years) with CHF, New York Heart Association (NYHA) Class II, III who were treated with lisinopril [Angiotensin-Converting Enzyme Inhibitor (ACEI)], frusemide (diuretic) and digoxin. All patients were subjected to resting 12-lead electrocardiography (ECG) and ventricular arrhythmias were analysed in relation to serum magnesium concentration at baseline and at end of the fourth week of treatment. Control group (Group II; 24 male, 21 female; the average age 49.3 years) were matched with Group I. Serum magnesium was determined by Atomic Absorption Spectrophotometer (AAS). Statistical analysis was with Student's t-test. It was observed that 6 (13.3%) CHF patients had ventricular arrhythmias at the commencement of the study. This number increased to 17 (37.8%) by the end of the fourth week of treatment. At four weeks, there was significant difference in serum magnesium between CHF patients without arrhythmias (0.69 +/- 0.11 mmol x L(-1)) and those with arrhythmias (0.50 +/- 0.01 mmol x L(-1)), P < 0.0001. Results obtained suggest that CHF patients having hypomagnesemia had higher prevalence of ventricular arrhythmias. It should be stressed, however, that 24 hour ECG monitoring and classification of ventricular arrhythmias according to Lown may give a more accurate picture. Nevertheless, routine serum magnesium assays, as part of the electrolyte profile of CHF patients would assist in early prevention and detection of magnesium depletion. This would go a long way to reduce the susceptibility to lethal arrhythmias and sudden death.

Serum and urinary magnesium during treatment of patients with chronic congestive heart failure.

Electrolyte disturbances are common in patients with Congestive Heart Failure (CHF) especially during long-term treatments. Unlike potassium, little is known of how magnesium is affected in these patients. This study was carried out to determine the serum and urinary concentration of magnesium in patients with CHF who were treated with lisinopril [Angiotensin-Converting Enzyme Inhibitor (ACEI)], frusemide (diuretic) and digoxin, at baseline, 2 weeks and 4 weeks. 45 patients (Group I; 24 male, 21 female; average age 49.7 years) with CHF, New York Heart Association (NYHA) Class II, III were matched with 45 healthy controls (Group II; 24 male, 21 female, average age 49.3 years). Serum and urinary magnesium were assayed by atomic absorption spectrophotometer. Statistical analysis was made by Student's t-test. At baseline, serum magnesium concentration in CHF patients was not significantly lower than in controls, p > 0.1. However, a higher loss of magnesium in urine was found in CHF patients compared with control subjects at baseline, p < 0.01. Serum magnesium concentration decreased significantly during treatment except in CHF patients on lisinopril, p < 0.05. The lowest excretion of magnesium was also found in this group of patients. Our study shows that lisinopril is magnesium-sparing in patients with CHF.

Erythrocyte membrane ouabain-sensitive Na+, K(+)-ATPase of hypertensive Nigerians.

An assessment of the ATPase functions of erythrocyte membrane of newly identified subjects having essential hypertension shows that Na+,K(+)-ATPase activity is higher in normal membranes than in membranes of individuals with essential hypertension. A study of the dependence of the enzyme on ATP in the presence of non-limiting concentrations of Na+ (120 mM) and Mg2+ (3 mM) shows that the pump in the membranes of hypertensive individuals, like that of normal humans, is easily saturable by ATP (greater than or equal to 2 microM). Analysis of the results of kinetic studies on the enzyme, in the presence of 5 mM K+, using the Hanes plot, reveals that, although the affinity (Km) of the pump for ATP is unaffected in essential hypertension, its maximum velocity (Vmax) is lower than in normal membranes. Even though the reason for a reduced sodium pump function in essential hypertension is not yet clear, it may not be unconnected with the presence of an endogenous inhibitor or with genetic or diet-induced membrane defects, as previously proposed by other workers in this area of research.

Inhibition of erythrocyte membrane Ca(2+)-pumping ATPase of hypertensive humans by nifedipine, a calcium entry blocker.

Nifedipine, a 1,4-dihydropyridine antihypertensive drug, inhibited the basal activity of erythrocyte Ca2+,Mg(2+)-ATPase of hypertensive individuals in a concentration-dependent manner. About 50% inhibition was obtained at nifedipine concentrations greater than or equal to 300 microM. The extent of inhibition of the ATPase action was increased in the presence of calmodulin. Maximal inhibition at 400 microM was 76%. Furthermore, the activity of the partially trypsinized enzyme was inhibited by about 50% by 300 microM nifedipine. Similar results were obtained with membranes from normotensive individuals. These findings suggest that nifedipine could prevent Ca(2+)-pumping by the erythrocyte Ca2+,Mg(2+)-ATPase.

Electrocardiographic hypertrophic patterns in hypertensive Nigerians.

We studied hypertrophic patterns in the electrocardiograms of 60 Nigerian hypertensives. Thirty were in heart failure and 30 without failure (matched for age and sex). Combined left ventricular and left atrial hypertrophy was the commonest finding occurring in 58.3%, followed by left ventricular hypertrophy alone in 30%. 76.7% and 40% had combined left ventricular and left atrial hypertrophy in the heart failure and the non-heart failure groups, respectively (P less than 0.02). Though these changes increased with increased blood pressure, the latter is similarly severe in both groups. 100% of patients in Class IV failure had combined left ventricular and left atrial hypertrophy. The 3 patients who had additional right atrial hypertrophy were in Class IV failure, 2 of whom died during follow-up. These changes are much more marked at presentation than reprots in caucasians and even in previous reports in Africans. The changes reflect the long-standing nature and severity of the hypertensive process, and point to the fact that the majority of hypertensives in this environment present rather late.

Distribution of antibodies against Coxsackie B viruses, arboviruses and Toxoplasma gondii among patients with endomyocardial fibrosis (EMF) compared with normal subjects from EMF endemic and non-endemic zones of Nigeria.

The sera of eight endomyocardial fibrosis (EMF) subjects, 11 siblings of one of them and 16 normal children matched with the EMF patients for age, sex and socio-economic status from Ogunmakin and Shao/Oloru communities (eight each), situated in EMF-endemic and non-endemic areas of Nigeria respectively, were examined for the presence of antibodies against Coxsackie viruses B1-6, 16 arboviruses and Toxoplasma gondii. Sera from 36 other randomly selected normal children from Ogunmakin and 26 other randomly selected children from Shao/Oloru were also tested for the presence of antibodies against Toxoplasma gondii and the 16 arboviruses. None of the eight EMF subjects nor the 11 siblings of one of them had antibodies against any of the Coxsackie viruses B1-6 in their sera. Two of the 16 matched control subjects, one from each community, had positive antibodies, at equivocal titres against Coxsackie B1 (Ogunmakin) and B4 (Shao/Oloru). There was no significant difference in the distribution of antibody titres to the arboviruses between the EMF patients and matched controls. Normal children from the Shao/Oloru community had higher percentage antibody reactions and higher titres to the arboviruses compared with the children from Ogunmakin. All the eight EMF patients had high antibody titres against Toxoplasma gondii. Seven (87.5%) of the matched controls from Ogunmakin were sero-positive for Toxoplasma gondii compared with three (37.5%) of the matched controls from Shao/Oloru. Of the 36 normal children from Ogunmakin, 32 (88.9%) were sero-positive compared with 11 (42.3%) of the 26 normal children from Shao/Oloru. Four (36.4%) of the 11 siblings of one of the EMF patients had weak sero-positivity. It is therefore concluded that further studies are needed to clarify the role, if any, of Toxoplasma gondii in EMF.