Immunohistological and serological studies in endomyocardial fibrosis

Endomyocardial fibrosis with ischaemic stroke

A Caucasian man in his mid-50s presented to the emergency department with sudden onset right-sided weakness and dysarthria. CT angiogram demonstrated a small volume of left middle cerebral artery territory infarction after which the patient underwent successful thrombolysis. Initial ECG showed diffuse T wave inversion. He was admitted to an acute stroke ward where 72 hours of telemetry demonstrated normal sinus rhythm without arrhythmia. Transthoracic echocardiogram showed a reduced ejection fraction of 47% in the absence of any regional wall motion abnormality. An echogenic mass was noted in the apical inferior septal wall. Cardiac MRI demonstrated circumferential mid to apical endocardial thickening with characteristic appearances consistent with endomyocardial fibrosis (EMF). Furthermore, a visible hypointensity in the apex confirmed left ventricular thrombus adherent to the area of EMF. The patient was started on anticoagulation and heart failure therapy. He has recovered from the ischaemic stroke and is currently under outpatient surveillance.

Endomyocardiofibrosis: A Systematic Review

Endomyocardiofibrosis was described first time in Uganda as an infrequent restrictive cardiomyopathy with a poor prognosis, characterized by fibrosis of the ventricular subendocardium and severe restrictive physiology leading to difficult therapeutic management and frequently associated with hypereosinophilic syndrome. Its higher prevalence in the tropics and its relationship in some cases with hypereosinophilic endocarditis has led to the search for genetic, infectious, autoimmune and nutritional causes, but its etiology remains unclear. It is a rare cardiomyopathy, difficult to diagnose and with a nonexistent effective treatment. Imaging methods such as echocardiography and cardiac magnetic resonance are essential for the initial diagnosis, although endomyocardial biopsy establishes the definitive diagnosis. Immunosuppressive treatment is only useful in the early stages of the disease and usually ineffective if installed late when signs of heart failure are present. Surgical treatment is generally palliative.

Endomyocardial Fibrosis: an Update After 70 Years

PURPOSE OF REVIEW

This review aims at highlighting the need to better understand the pathogenesis and natural history of endomyocardial fibrosis when set against its changing endemicity and disease burden, improvements in diagnosis, and new options for clinical management.

RECENT FINDINGS

Progress in imaging diagnostic techniques and availability of new targets for drug and surgical treatment of heart failure are contributing to earlier diagnosis and may lead to improvement in patient survival. Endomyocardial fibrosis was first described in Uganda by Davies more than 70 years ago (1948). Despite its poor prognosis, the etiology of this neglected tropical restrictive cardiomyopathy still remains enigmatic nowadays. Our review reflects on the journey of scientific discovery and construction of the current guiding concepts on this mysterious and fascinating condition, bringing to light the contemporary knowledge acquired over these years. Here we describe novel tools for diagnosis, give an overview of the improvement in clinical management, and finally, suggest research themes that can help improve patient outcomes focusing (whenever possible) on novel players coming into action.

Tropical Endomyocardial Fibrosis: Natural History, Challenges, and Perspectives

Tropical endomyocardial fibrosis (EMF) is a neglected disease of poverty that afflicts rural populations in tropical low-income countries, with some certain high-prevalence areas. Tropical EMF is characterized by the deposition of fibrous tissue in the endomyocardium, leading to restrictive physiology. Since the first descriptions in Uganda in 1948, high-frequency areas for EMF have included Africa, Asia, and South America. Although there is no clear consensus on a unified hypothesis, it seems likely that dietary, environmental, and infectious factors may combine in a susceptible individual to give rise to an inflammatory process leading to endomyocardial damage and scar formation. The natural history of EMF includes an active phase with recurrent flare-ups of inflammation evolving to a chronic phase leading to restrictive heart failure. In the chronic phase, biventricular involvement is the most common presentation, followed by isolated right-sided heart disease. Marked ascites out of proportion to peripheral edema usually develops as a typical feature of EMF. EMF carries a very poor prognosis. In addition to medical management of heart failure, early open heart surgery (endocardectomy and valve repair/replacement) appears to improve outcomes to some extent; however, surgery is technically challenging and not available in most endemic areas. Increased awareness among health workers and policy makers is the need of the hour for the unhindered development of efficient preventive and therapeutic strategies.

Endomyocardial fibrosis: A form of endemic restrictive cardiomyopathy

Endomyocardial fibrosis is a form of endemic restrictive cardiomyopathy that affects mainly children and adolescents, and is geographically restricted to some poor areas of Africa, Latin America and Asia. It is a condition with high morbidity and mortality, for which no effective therapy is available. Although several hypotheses have been proposed as triggers or causal factors for the disease, none are able to explain the occurrence of the disease worldwide. In endemic areas of Africa endomyocardial fibrosis is as common a cause of heart failure as rheumatic heart disease, accounting for up to 20% of cases of heart failure and imposes a considerable burden to the communities and the health systems. However, due to lack of resources for research in these areas, the exact epidemiology, etiology and pathogenesis remain unknown, and the natural history is incompletely understood. We here review the main aspects of epidemiology, natural history, clinical picture and management of endomyocardial fibrosis, proposing new ways to increase research into this challenging and neglected cardiovascular disease.

The myocardium of fetuses with endocardial fibroelastosis contains fewer B and T lymphocytes than normal control myocardium

The observation that endocardial fibroelastosis (EFE) can result from an immune response to maternal autoantibody deposition in the fetal myocardium raises the possibility that the fetal immune system may contribute to the pathogenesis of idiopathic EFE and dilated cardiomyopathy (DCM). This study sought to characterize myocardial immune cell presence in fetuses and neonates with idiopathic EFE + DCM, in those with EFE + structural heart disease, and in normal control subjects. Paraffin tissue sections from fetuses identified from the pathology database were stained for B cell, T cell, macrophage, and general hematopoietic cell surface markers. Of the 14 fetuses included in the study, 5 had EFE + DCM, 4 had EFE + structural heart disease, and 5 were normal control fetuses. The EFE + DCM group had fewer B cells than the control group (0.15 vs. 0.44 cells/mm(2); p = 0.005). The EFE + heart disease group had both fewer B cells (0.18 vs. 0.44 cells/mm(2); p = 0.08) and T cells (0.29 vs. 0.80 cells/mm(2); p = 0.04) than the control group. The CD4/CD8 ratio was similar in the EFE + DCM and EFE + heart disease groups (1.0 vs. 0.9; p = 0.17) but higher in the EFE + DCM group than in the control group (0.9 vs. 0.3; p = 0.03). The myocardium of fetuses with EFE contains fewer B and T lymphocytes than normal control fetuses.

Presence of circulating anti-myosin antibodies in endomyocardial fibrosis

Background

Endomyocardial Fibrosis (EMF) is a tropical restrictive cardiomyopathy of unknown etiology with high prevalence in Sub-Saharan Africa, for which it is unclear whether the primary target of injury is the endocardial endothelium, the subendocardial fibroblast, the coronary microcirculation or the myocyte. In an attempt to explore the possibility of endocardial lesions being a result of an immune response against the myocyte we assessed the presence and frequency of circulating anti-myocardial antibodies in EMF patients.

Methodology/Principal Findings

EMF classification, assessment of severity and staging was based on echocardiography. We used sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) of myocardial proteins followed by western blotting to screen serum samples for antiheart antibodies G and M classes. The degree of serum reactivity was correlated with the severity and activity of EMF. We studied 56 EMF patients and 10 healthy controls. IgG reactivity against myocardial proteins was stronger and more frequent in patients with EMF when compared to controls (30/56; 53.6% vs. 1/10; 10%, respectively). IgM reactivity was weak in both groups, although higher in EMF patients (11/56; 19.6%) when compared to controls (n = 0). EMF patients showed greater frequency and reactivity of IgG antibodies against myocardial proteins of molecular weights 35 kD, 42 kD and 70 kD (p values <0.01, <0.01 and <0.05 respectively).

Conclusions

The presence of antibodies against myocardial proteins was demonstrated in a subset of EMF patients. These immune markers seem to be related with activity and might provide an adjunct tool for diagnosis and classification of EMF, therefore improving its management by identifying patients who may benefit from immunosuppressive therapy. Further research is needed to clarify the role of autoimmunity in the pathogenesis of EMF.

Endomyocardial Fibrosis is a tropical disease in which the heart cannot open properly to receive blood due to a scar that covers its inner layer. It affects mainly children and adolescents, and has a poor prognosis because the cause and mechanisms of scarring are unknown. The conventional treatment is frustrating and does not alter the natural history of the disease. Despite affecting several million people worldwide there has been little investigation on the mechanisms of the disease or drug development to improve its prognosis. In this study we investigate the presence of antibodies against the myocardial cells of African patients with severe and advanced EMF aiming at uncovering new pathways for the disease. Our results reveal that EMF patients have anti-myocardial antibodies in their blood. The reaction of these antibodies with the heart may be one of the mechanisms involved in the genesis of the fibrotic lesions. This knowledge may help in diagnosing the condition and provide alternatives for its management, using drugs that reduce the impact of the circulating antibodies in the cardiac tissue. The significance of these results needs confirmation on studies involving larger number of subjects due to frequent finding of antiheart antibodies in African populations with heart failure of any cause.

Immunoglobulins and complement in chronic myocardial disease. A myocardial biopsy study

Autoimmune mechanisms have been suggested to be of significance in chronic myocardial diseases. However, the frequency and importance of these factors are unknown. In the present study, endomyocardial biopsy specimens from 21 patients with chronic myocardial disease have been examined by direct immunofluorescence for the presence of immunoglobulins and complement factor C3. Positive staining for immunoglobulin and/or complement was observed in 7 cases. None of the specimens stained for albumin or amyloid. The immunoglobulin deposits were located on the surface of the myofibre and in all but one case, complement was found in the same location. The presence of the complement together with immunoglobulin, and also the lack of albumin, may suggest an immune reaction and not just a passive deposition secondary to heart muscle damage. The localization along the fibres further suggests that the deposits represent an autoimmune reaction to antigens on the fibres and not a trapping of circulating antigen-antibody complexes. It is not known whether the deposits are primary or secondary events, but they may be of importance in initiating or maintaining derangement in heart function.

Endomyocardial fibrosis: still a mystery after 60 years

The pathologist Jack N. P. Davies identified endomyocardial fibrosis in Uganda in 1947. Since that time, reports of this restrictive cardiomyopathy have come from other parts of tropical Africa, South Asia, and South America. In Kampala, the disease accounts for 20% of heart disease patients referred for echocardiography. We conducted a systematic review of research on the epidemiology and etiology of endomyocardial fibrosis. We relied primarily on articles in the MEDLINE database with either “endomyocardial fibrosis” or “endomyocardial sclerosis” in the title. The volume of publications on endomyocardial fibrosis has declined since the 1980s. Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution.

Epidemiology, etiology, detection, and treatment of autoantibody-associated congenital heart block in neonatal lupus

Neonatal lupus syndrome is a model of passively acquired autoimmunity in which the pregnant woman's serum contains specific antibodies to 52 or 60 kd SSA/Ro and/or 48 kd SSB/La, which cross the placenta and are associated with the development of congenital heart block in the fetus and/or a transient rash or various liver and blood cell abnormalities in the newborn. To date, congenital heart block is a permanent condition that entails significant morbidity and mortality, with nearly all affected infants requiring pacemakers and with an 80% cumulative probability of survival at 3 years of age. An intensive search is on for the specific etiopathophysiology and for new clinical tools to approach and treat this disease.

Endocardial fibroelastosis associated with maternal anti-Ro and anti-La antibodies in the absence of atrioventricular block

OBJECTIVES

This study was designed to document the association of endocardial fibroelastosis (EFE) and maternal autoantibodies.

BACKGROUND

Neonatal lupus erythematosus is associated with the transplacental passage of maternal anti-Ro and anti-La antibodies, leading to complete atrioventricular block (CAVB). In some cases, CAVB is associated with EFE. Isolated EFE may be independently related to maternal anti-Ro and anti-La antibodies.

METHODS

We identified three cases (one fetus and two infants, all female) of isolated EFE in infants born to autoantibody-positive mothers in the absence of CAVB. Demographics, echocardiograms, and pathology were reviewed. Immunohistochemical analyses for immunoglobulin (Ig)G, IgM, IgA, T-cell, B-cell, and terminal deoxynucleoleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) (test for cell apoptosis) staining were performed on multiple sections of the heart in each case and compared with negative controls.

RESULTS

Two cases died and one received a cardiac transplant. All three cases had histologically confirmed EFE. All cases demonstrated significant diffuse IgG infiltration. To a lesser extent, myocardial tissue was also positive for IgM, CD43, and Granzyme B. None of the specimens were TUNEL positive.

CONCLUSIONS

These are the first reported cases of isolated EFE associated with maternal anti-Ro and anti-La antibodies in the absence of CAVB. The diffuse deposition of IgG and the presence of a T-cell infiltrate throughout the myocardium suggest that the transplacental passage of maternal autoantibodies induces an immune reaction within the myocardium, leading to isolated EFE. Autoantibody-mediated EFE may be an etiologic factor in cases of fetal and neonatal "idiopathic" dilated cardiomyopathy.

Maternal anti-Ro and anti-La antibody-associated endocardial fibroelastosis

BACKGROUND

Maternal anti-Ro and anti-La antibodies are associated with congenital heart block (CHB). Although endocardial fibroelastosis (EFE) has been described in isolated cases of autoantibody-mediated CHB, the natural history and pathogenesis of this disease are poorly understood.

METHODS AND RESULTS

We retrospectively reviewed the clinical history, echocardiography, and pathology of fetuses and children with EFE associated with CHB born to mothers positive for anti-Ro or anti-La antibodies at 5 centers. Thirteen patients were identified, 6 with a prenatal and 7 with a postnatal diagnosis. Six mothers were positive for anti-Ro and anti-La antibodies, and 7 were positive for anti-Ro antibodies only. Only 1 mother had autoimmune disease. Severe ventricular dysfunction was seen in all fetal and postnatal cases. Four fetal and 3 postnatal cases had EFE at initial presentation. However, 2 fetal and 4 postnatal cases developed EFE 6 to 12 weeks and 7 months to 5 years from CHB diagnosis, respectively, even despite ventricular pacing in 6 postnatal cases. Eleven (85%) either died (n=9) or underwent cardiac transplantation (n=2) secondary to the EFE. Pathologic assessment of the explanted heart, available in 10 cases, revealed moderate to severe EFE in 7 and mild EFE in 3 cases, predominantly involving the left ventricle. Immunohistochemistry in 4 cases (including 3 fetuses) demonstrated deposition of IgG in 4 and IgM in 3 and T-cell infiltrates in 3 cases, suggesting an immune response by the affected fetus or child.

CONCLUSIONS

EFE occurs in the presence of autoantibody-mediated CHB despite adequate ventricular pacing. Autoantibody-associated EFE has a very high mortality rate, whether developing in fetal or postnatal life.

Helminth associated hypereosinophilia and tropical endomyocardial fibrosis (EMF) in Nigeria

There should be a recognisable trend between the incidence of hypereosinophilia and the duration of tropical endomyocardial fibrosis (EMF), if the hypothesis, that EMF is the burnt out phase of eosinophil associated heart disease, is correct. We tested this hypothesis in a prospective study of 89 consecutive EMF cases over an 18 year period at two Nigerian locations (Ife in South West and Calabar in South East). We carefully dated the duration of EMF symptoms at first presentation and screened for hypereosinophilia (eosinophilia > or = 1500/mm3), and their causes. When no cause was identified for hypereosinophilia we gave a therapeutic trial with diethylcarbamazine to the patients. An eosinophil count > or = 1000/mm3 was recorded in 80% of 24 cases seen within 6 months; 55% of 46 cases seen 0-24 months; 54% of 18 cases seen 25-48 months and 21% of 25 cases seen more than 49 months of onset of symptoms: while the respective distribution of eosinophil count > or = 1500/mm3 for similar periods were 66, 44, 27 and 21%. This reflects a highly significant (P < 0.001) inverse relationship between hypereosinophilia and the duration of EMF and strengthens the concept that EMF (without eosinophilia) represents the late stage of eosinophilic heart disease. The localisation of endemic EMF to the low-lying tropical rain forest Zone and its predominant occurrence among rural dwellers and farmers suggest a vector borne etiologic agent. Microfilaria was the most likely cause of hypereosinophilia in the cases presented.

Renal lesions in the obliterative cardiomyopathies: endomyocardial fibrosis and Loffler's endocarditis

Electron and, or light microscopic examination of paraffin embedded renal tissue obtained from necropsies on eleven patients with obliterative cardiomyopathy showed a variety of abnormalities. Glomerular lesions present in patients with endomyocardial fibrosis included capillary wall thickening, basement membrane duplication, mesangial expansion and interposition, intraluminal fibrin and dense subendothelial deposits. These changes, some of which have been reported earlier in patients with Loffler's endocarditis, probably result from deposition and organisation of immune complexes.

Endomyocardial fibrosis in Africa

Endomyocardial fibrosis (EMF) is a disease of the rain-forest belt in Africa. There is general agreement as to its pathology in the acute phase, but this is difficult to diagnose clinically. The aetiology is still unknown although there are reports which suggest that eosinophilic endomyocardial disease may be the cause. Further studies are needed to define EMF in its acute stage and find out how chronic EMF evolves. A longitudinal study on young people with eosinophilia and a comparative study of two villages, one in an endemic zone and the other in a zone where EMF is uncommon, will also be helpful in identifying its cause. The most promising form of treatment at present is surgical.

Mixed cryoglobulinemia: clinical aspects and long-term follow-up of 40 patients

The clinical course of 40 patients with significant quantities of mixed cryoglobulins, but without lymphoproliferative, collagen-vascular or chronic infectious diseases, is presented. These cases comprise 51.3 percent of all mixed and 31.7 percent of all types of cryoglobulins evaluated by us over the period 1960--1978. A characteristic clinical syndrome, consisting of recurrent palpable purpura (100 percent), polyarthralgias (72.5 percent) and renal disease (55 percent), was seen. Biopsy specimens of skin lesions showed cutaneous vasculitis, and half had immune reactants in vessel walls. Seventy percent of patients had evidence of hepatic dysfunction, often subclinical, and more than 60 percent of those tested had serologic evidence of prior infection with hepatitis B virus. Hepatic lesions ranged from minimal triaditis to chronic active hepatitis and/or cirrhosis. All 22 patients in whom clinical renal disease developed had significant proteinuria; 63.6 percent had diastolic hypertension, 77.3 percent edema, 45.5 percent renal failure and 22.7 percent were nephrotic. Glomerular disease associated with deposition of immunoglobulin G, immunoglobulin M and complement, often with coexistent renal arteritis, was confirmed pathologically in 15 cases. All cryoglobulins had rheumatoid factor activity and consisted of IgM and polyclonal IgG; five also contained IgA. Thirteen had a monoclonal IgM kappa component. Serum protein electrophoresis was unremarkable or showed diffuse hyperglobulinemia. Striking depression of early complement components was noted but did not correlate well with the cryoprotein concentration, renal involvement or clinical course. Follow-up for periods up to 21 years from onset of symptoms revealed that renal involvement has a deleterious effect on prognosis. Postmorten examinations of nine patients demonstrated widespread vasculitis in addition to renal involvement. Preterminal infection was found in eight.

Pancarditis with valvulitis in endomyocardial fibrosis (=emf) and in human African trypanosomiasis (= hat). A comparative histological study of four Ugandan cases

The study compares the histotopographical lesions of two cases of endomyocardial fibrosis with those of two hearts in sleeping sickness, all of them from Uganda. There was considerable overlapping of the fibrosed zones in endomyocardial fibrosis and the corresponding sites occupied by the chronic inflammatory process in trypanosomiasis. There was a tendency towards fibrosis in the hearts of trypanosomiasis while, in endomyocardial fibrosis, there were mild focal chronic cellular infiltrations. This overlapping and to some extent similarities would suggest that the two conditions may only differ in evolution in time and intensity and that they may be the result of the same inflammatory process. Stipulating a cardiac tropism for African trypanosomes, it is suggested that some African cases of endomyocardial fibrosis may be merely burnt-out lesions of trypanosomal pancarditis. Previous descriptions of carditis in human African and American trypanosomiasis are briefly reviewed, and the present findings are discussed in view of a possible trypanosomal aetiology in some African cardiomyopathies.

Primary restrictive cardiomyopathy. Non-tropical endomyocardial fibrosis and hypereosinophilic heart disease

Eleven patients with a restrictive cardiomyopathy are described. Seven of these had biventricular disease and in them the haemodynamic abnormality resembled that in constrictive pericarditis but the condition was distinguishable because of unequal involvement of the two ventricles, murmurs of atrioventricular valve regurgitation, or characteristic ventricular deformity on angiography. Two of these patients had eosinophilia with the clinical features of Löffer's endocarditis. In 4 patients the disease was apparently confined to the left ventricle; they were investigated on account of atypical chest pain, third heart sound, or abnormal electrocardiogram. Simultaneous measurements of left ventricular pressure and volume throughout diastole were made in 3 patients and showed rapid but abruptly curtailed left ventricular filling. Transvenous endomyocardial biopsy in 2 patients showed fibrous tissue with collagen and irregular elastic fibrils. Surgical biopsy in 3 patients excluded pericardial constriction but was diagnostically unhelpful because of failure to obtain endocardium. Necropsy in one patient showed that the heart had features indistinguishable from tropical endomyocardial fibrosis. It is suggested that the spectrum of ventricular abnormalities in these patients results from endomyocardial fibrosis of varying severity and probably of differing cause. This study has shown that "tropical" endomyocardial fibrosis may occur outside the tropics and suggests that eosinophilia may play a leading role or associated part in the genesis of some cases.

Endomyocardial fibrosis and eosinophilia

Absolute eosinophil counts were assessed in 15 African patients with proven endomyocardial fibrosis. Though the mean eosinophil count in patients with endomyocardial fibrosis was higher compared with the normals reported from Kampala (1-13 vs 0.72X10(9)/1), the absolute range was comparable. A high percentage of patients with endomyocardial fibrosis had malarial parasites, high malarial antibody titres, hookworms, or strongyloides, but the correlation of eosinophilia to various parasitic infections was poor. Both eosinophilia and parasitic infections are common in the tropics and they effect patients with endomyocardial fibrosis no more than the population at large. Other aetiological factors, genetic, environmental, and immunological, are felt to be important in the causation of endomyocardial fibrosis in Uganda and evidence for this is reviewed. Though there is a similarity in pathological features, African endomyocardial fibrosis is a distinct entity from Löffler's endocarditis and cardiac lesions seen in eosinophilic leukaemia or reactive eosinophilia. There is no hard evidence to suggest that African endomyocardial fibrosis is a variant of Löffler's endocarditis caused by parasitic infections via eosinophilia.

Chagasic cardiopathy. Antibodies reacting with plasma membrane of striated muscle and endothelial cells

An antibody reacting with endocardium, vascular structures and interstitium of striated muscle (EVI antibody), by the indirect immunofluorescence technique, was recently described in Chagas' disease. In the present report the identification of tissue structures responsible for the EVI reaction was studied by means of ultrastructural immunochemical methods. Positive reactions were observed in the plasma membrane of the heart and skeletal muscle fibers and endothelial cells of blood vessels.

Absorption of positive sera with T. cruzi abolished both patterns observed by electron microscopic methods. These results are in agreement with observations performed with the indirect immunofluorescence technique.

Tropical splenomegaly syndrome in a Rwandan kindred in Uganda

Twenty members of an immigrant Rwandan kindred were all found to have tropical splenomegaly syndrome compared with 29 out of 50 matched neighbour controls. Splenomegaly among the controls tended to cluster within families. IgM levels were significantly raised in the kindred compared with the control subjects without splenomegaly but were similar to those of neighbours with splenic enlargement. We advance a hypothesis that tropical splenomegaly syndrome results from the production of circulating immune complexes in individuals genetically predisposed to produce an IgM antibody response.

Familial cases of endomyocardial fibrosis in Uganda

This report describes nine cases of endomyocardial fibrosis occurring in four families. All patients came from Rwanda or South-western Uganda, and five had tropical splenomegaly syndrome as well. It seems likely that genetic as well as environmental factors are operative in the aetiology of endomyocardial fibrosis.

Immunoglobulin binding in cardiomyopathic hearts

Bound gamma globulin was demonstrated by the direct immunofluorescent technique in heart tissue from three patients with severe congestive cardiomyopathy. In two of these patients complement (β 1 C) was also bound to the heart muscle. Heart tissue from one of six patients who died of myocardial infarction showed a trace of bound gamma globulin, but no bound complement. During life, the heart in advanced cardiomyopathy may preferentially fix heart-reactive immunoglobulins to specific sarcolemmal and subsarcolemmal antigens, and antiheart antibody may not be detectable in the serum.

Studies on platelet 5-hydroxytryptamine in East Africans

1. A study was done on the platelet 5-hydroxytryptamine (5HT) from Africans in areas where endomyocardial fibrosis is common.

2. There were only small differences between the mean platelet or blood5HT in Europeans and plantain-eating Africans; the distribution of the results showed a wider scatter in the African community, including values outside the upper limits of normal but not within the range reported for carcinoid.

3. Patients in hospital had lower platelet5HT contents regardless of cardiac condition or disease than healthy Africans on similar diets, suggesting no specific abnormality related to platelet5HT levels and endomyocardial fibrosis.

4. A small number of radioactive studies suggested that only 1–4 % of oral5HT may reach the platelets; a significant increase in platelet5HT did occur after a plantain meal; the in-crease after a meal but not after oral5HT may be explained by release of endogenous5HT from the small intestine under the influence of the high bulk of the diet. Attention is drawn to the high incidence of adult intussusception and volvulus associated with such diets.

Intracardiac electrocardiogram in endomyocardial fibrosis

Images

Clinical features of endomyocardial fibrosis of the right ventricle

Images