Positive skin reactivity to mumps virus antigen in endocardial fibroelastosis

Paediatric dilated cardiomyopathy with and without endocardial fibroelastosis - a pathological analysis of 89 explants

Heart failure due to dilated cardiomyopathy is a major indication for paediatric cardiac transplantation. Endocardial fibroelastosis is a recognised pathological finding of unknown prognostic significance in paediatric dilated cardiomyopathy. To evaluate the nature of the association between left ventricular endocardial fibroelastosis and paediatric dilated cardiomyopathy, we reviewed surgical pathology reports of dilated cardiomyopathy explants (1986-2016) in order to characterise the pathological findings and to compare and contrast their frequency among four age groups: less than 1 year; 1-5 years; 6-10 years; and greater than 11 years. The 89 explants (47 males and 42 females) were all characterised by increased weight and left ventricular chamber dilatation without increased wall thickness. Ninety-five per cent of the specimens in the two youngest subsets had left ventricular endocardial fibroelastosis. Compared to the oldest age group, recipients aged 1-5 years had a 6-fold increase and those younger than 1 year a 19-fold increase in the odds of observing left ventricular endocardial fibroelastosis. Explants with and without endocardial fibroelastosis were otherwise phenotypically similar. In paediatric dilated cardiomyopathy endocardial fibroelastosis is a very common pathological finding, especially in infants and young children. We propose that the descriptive, clinico-pathological designation "Dilated Cardiomyopathy with Endocardial Fibroelastosis" should be adopted to facilitate future investigation into the potential prognostic/therapeutic significance of left ventricular endocardial fibroelastosis.

Analysis of formalin-fixed and frozen myocardial autopsy samples for viral genome in childhood myocarditis and dilated cardiomyopathy with endocardial fibroelastosis using polymerase chain reaction (PCR)

Viral infection of the myocardium is implicated in the pathogenesis of myocarditis and dilated cardiomyopathy (DCM). Enteroviruses have been considered the most common viral etiologic agents, based on peripheral culture and serologic methods. Recently, polymerase chain reaction (PCR) has been shown to be useful in the detection of viral genomes from various infected organs and body fluids. In this study, myocardial samples from autopsy specimens (formalin fixed and fresh frozen) were examined for enteroviral and DNA viral (adenovirus, herpes simplex virus [HSV], and cytomegalovirus (CMV]) genome by PCR. The specimens studied were from 58 patients with myocarditis, 28 patients with DCM and endocardial fibroelastosis [EFE], and 22 controls. Viral genome was detectable in 34 of the 58 (59%) autopsy-proven myocarditis samples (18 adenovirus, 12 enterovirus, 2 CMV, 2 HSV) and 6 of the 28 samples from patients with DCM and EFE (6 adenovirus). We conclude that PCR is effective in the rapid amplification of virus from frozen and formalin-fixed myocardial samples and that adenovirus is an important etiologic agent in viral myocarditis as well as DCM with EFE.

Changing concepts of endocardial fibroelastosis

Endocardial fibroelastosis is not a disease but a reaction of the endocardium. I review the history of the term with emphasis on the gradual understanding of the many causes of this reaction. I include a comprehensive list of diseases or other cardiac stresses that authors have reported in association, and I try to explain the mechanism of the reaction. Although endocardial fibroelastosis is rare today, I issue a warning of a possible epidemic recrudescence of some of the associated diseases. My hope is for nosologic purity, therefore that outworn but surviving concepts will be firmly rejected.

Inflammatory cardiomyopathy: there is a specific matrix destruction in the course of the disease

Cardiomyopathies are responsible for a high proportion of cases of congestive heart failure and sudden death, as well as for the need for transplantation. Understanding of the causes of these disorders has been sought in earnest over the past decade. We hypothesized that DCM is a disease of the cytoskeleton/sarcolemma, which affects the sarcomere. Evaluation of the sarcolemma in DCM and other forms of systolic heart failure demonstrates membrane disruption; and, secondarily, the extracellular matrix architecture is also affected. Disruption of the links from the sarcolemma to ECM at the dystrophin C-terminus and those to the sarcomere and nucleus via N-terminal dystrophin interactions could lead to a "domino effect" disruption of systolic function and development of arrhythmias. We also have suggested that dystrophin mutations play a role in idiopathic DCM in males. The T-cap/MLP/alpha-actinin/titin complex appears to stabilize Z-disc function via mechanical stretch sensing. Loss of elasticity results in the primary defect in the endogenous cardiac muscle stretch sensor machinery. The over-stretching of individual myocytes leads to activation of cell death pathways, at a time when stretch-regulated survival cues are diminished due to defective stretch sensing, leading to progression of heart failure. Genetic DCM and the acquired disorder viral myocarditis have the same clinical features including heart failure, arrhythmias, and conduction block, and also similar mechanisms of disease based on the proteins targeted. In dilated cardiomyopathy, the process of progressive ventricular dilation and changes of the shape of the ventricle to a more spherical shape, associated with changes in ventricular function and/or hypertrophy, occurs without known initiating disturbance. In those cases in which resolution of cardiac dysfunction does not occur, chronic DCM results. It has been unclear what the underlying etiology of this long-term sequela could be, but viral persistence and autoimmunity have been widely speculated.

Viral infection of the myocardium in endocardial fibroelastosis. Molecular evidence for the role of mumps virus as an etiologic agent

BACKGROUND

Endocardial fibroelastosis, previously a common disease of children, often resulted in congestive heart failure and death. Virus-induced myocarditis was the suspected first step in the pathogenesis of the disease, with enteroviruses and mumps virus considered potential causes. Direct evidence for their involvement was limited, however, and during the past two decades, a significant decline in the incidence of endocardial fibroelastosis occurred. Recently, we demonstrated polymerase chain reaction to be a rapid and sensitive method for identification of the viral genome in the myocardium of patients with myocarditis and dilated cardiomyopathy. The purpose of this study was to analyze myocardial samples of patients with endocardial fibroelastosis for the viral genome.

METHODS AND RESULTS

Myocardial samples from 29 patients with autopsy-proven endocardial fibroelastosis were analyzed for viral genome (enterovirus, adenovirus, mumps, cytomegalovirus, parvovirus, influenza, herpes simplex virus) by use of polymerase chain reaction or reverse transcriptase-polymerase chain reaction. In 90% of samples, the viral genome was amplified; > 70% of the samples were positive for mumps viral RNA, while 28% amplified adenovirus. In contrast, only 1 of 65 control samples amplified a virus (enterovirus). Two regions of mumps virus were amplified: the nucleocapsid gene and the polymerase-associated protein gene. Interestingly, only 3 of the 21 samples that were positive for mumps RNA were positive with both sets of primers, indicating that the persistence of mumps virus in the myocardium may be related to the selection of defective virus mutants.

CONCLUSIONS

These data suggest an etiologic role for viral infection in endocardial fibroelastosis, supporting the hypothesis that endocardial fibroelastosis is a sequela of a viral myocarditis, in particular of that due to mumps virus.

ENDOCARDIAL FIBROELASTOSIS. A CLINICAL AND ANATOMIC STUDY OF 47 PATIENTS WITH EMPHASIS ON ITS RELATIONSHIP TO MITRAL INSUFFICIENCY

A clinical and pathologic study of 47 cases with endocardial fibroelastosis is presented. These cases have been classified according to the associated cardiac anomaly and the anatomic condition of the left ventricle. In so doing, a better understanding is had of the role the cardiac anomaly associated with endocardial fibroelastosis plays in the production of cardiac signs and symptoms.

In each of the specimens available for review, a change of the mitral valve was present that rendered it insufficient. Those cases grouped as primary endocardial fibro-elastosis had this as the only abnormality present, other than the endocardial fibroelastosis. Many of the clinical and laboratory findings in this group could be explained on the basis of mitral insufficiency, and one cannot necessarily assign the cardiac signs and symptoms to the endocardial process itself. In those cases with associated cardiac anomalies the hemodynamic consequences appear to be a summation of the combined effects of the mitral insufficiency, endocardial fibroelastosis, and the associated cardiac anomaly.

In this review, we were unable to distinguish, by either gross or microscopic methods, between primary and secondary endocardial fibroelastosis. Since use of these terms suggests etiologic relations, it is preferable to classify cases of endocardial fibroelastosis on the basis of the structural abnormalities present.

New syndrome of hydrocephalus, endocardial fibroelastosis, and cataracts (HEC syndrome)

We report on two unrelated male infants with similar findings of communicating hydrocephalus, endocardial fibroelastosis (EFE) and congenital cataracts, who died at 4 months of age. Both mothers reported an upper respiratory infection during the first trimester of pregnancy which was further complicated by polyhydramnios in the third trimester. The infants were diagnosed with bilateral congenital nuclear cataracts at birth. Serologic tests for toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus, syphilis, and galactosemia screens were negative. Chromosome analyses were normal. Both children developed communicating hydrocephalus between one and three months after birth. Patient 1 died suddenly at 4 months following an upper respiratory infection. Patient 2 developed congestive heart failure and also died at 4 months. At autopsy, both infants had enlarged hearts with endocardial fibroelastosis. No identifiable organism could be isolated. We discuss the association of birth defects in widely separated organ systems in these patients and suggest that this may represent a genetic syndrome; however, a viral etiology cannot entirely be excluded. We believe this is a distinct disorder and propose the acronym HEC for hydrocephalus, EFE and cataracts.

Viral infections during pregnancy: a guide for the emergency physician

Emergency physicians are frequently called on to treat or advise pregnant patients. When faced with a pregnant patient who has clinical evidence of or exposure to a viral illness, the emergency physician must be aware of the potential maternal and fetal risks posed by various viral agents. This review provides current, accurate information and guidance for the pregnant patient.

Endocardial fibroelastosis: myocardial and vascular alterations associated with viral-like nuclear particles

Although clinical, immunologic, and experimental evidence exists implicating in utero viral infection of the myocardium in the development of primary endocardial fibroelastosis, the infectious etiology of this condition remains somewhat controversial. To date, specific features of viral myocarditis and morphological demonstration of viral particles have not been described in EFE. The present case is the first in which extensive light microscopic and ultrastructural analysis of the myocardium revealed abnormalities consistent with a primary viral myocarditis associated with typical EFE. These alterations consisted of chronic myocardial inflammation, extensive interstitial fibrosis, severe degenerative changes in myocardial cells, and a marked proliferation of endothelial cells in large nad small intramyocardial vessels leading to vascular occlusions. In support of the infectious etiology of this disease, similar features were noted in skeletal muscle. Most interestingly, viral-like particles were observed in many myocardial and endothelial nuclei. Although we are not absolutely certain of the viral nature of these particles, their appearance suggests viral assoicated material. We propose that the presence of these particles in this case in association with the other morphological alterations in support for the viral etiology of EFE. The prominent vascular occlusion observed in the myocardium may be an important clue to the pathogenesis of fibroelastosis as either a primary or secondary disease.

Abnormalities of immunglobulins in infants with congenital heart disease

Twenty-eight infants had their serum immunoglobulins estimated (by radial immunodiffusion) in early infancy. The IgG level was abnormal in twelve infants. Elevated levels of IgA were found in ten and IgM in fourteen. These variations, mostly obvious in the first ten days of life, were detected in the absence of clinical or immunological evidence of congenital rubella infection.

The clinical course of primary myocardial disease in infants and children

A total of 161 infants and children, ranging in age from 1 day to 17 years at initial encounter (mean, 3.7 years), was seen over a 30 year period with primary myocardial disease (idiopathic myocarditis, nonobstructive cardiomyopathy, endocardial fibroelastosis, and an anatomically unknown category). These patients were observed from 1 hour to 23 years after initial encounter and cardiac disease has resolved in 27 per cent, resulted in death in 35 per cent, and continues in 38 per cent. The majority were first referred to us with congestive heart failure; all exhibited ST-T changes and cardiomegaly, 67 of 150 had left ventricular hypertrophy, 23 of 151 arrhythmias, and 55 of 153 pulmonary vascular congestion. Initial ventricular depolarization abnormalities were very frequent. Significant clinical predictors of fatal outcome included pulmonary vascular congestion, "northwest" axis deviation, and a cardiac index less than three L./min./M.2. Death occurred during the first year after initial encounter in 44 of 57 who died, and in all 13 with proved myocarditis. Primary myocardial disease is a serious disease of infancy and childhood, resulting in death or residual cardiac disease in three fourths of those affected.

Intrauterine virus infections and congenital heart disease

The etiologic basis for the vast majority of cases of congenital heart disease remains largely undefined. Viruses have been considered to be likely candidates since the recognition of the association between intrauterine rubella and congenital heart disease. Although the pathogenesis of cardiovascular defects is poorly understood, information gained from the study of congenital rubella syndrome suggests that mechanisms such as focal endothelial cell damage, resulting in obliteration of vascular supply, decreased growth rate, and shortened survival time of certain cells, and disturbed DNA replication in cells whose chromosomes were damaged secondary to the effects of virus replication may be operative in the production of defects in the developing fetus. In addition to rubella there is suggestive, but not conclusive, evidence that Coxsackie B3 and B4 virus infections during pregnancy can result in the birth of infants with a variety of types of congenital heart lesions and that intrauterine mumps virus infection may be etiologically related to the postnatal development of endocardial fibroelastosis (EFE). Although there are a number of other viruses that are potential etiologic agents of congenital heart disease, the current status of information is inadequate to allow even suggestive associations to be made. The most profitable areas for future investigation appear to be: (1) the epidemiology of congenital heart disease, (2) prospective studies of the association of maternal viral infection with abnormal offspring, (3) the in-depth virologic investigation of the infant with a cardiac defect, and (4) the development of experimental animal models of congenital heart disease. Successful control of virus-induced congenital heart disease will depend on the results of these investigations and the development of vaccines against the identified causative viruses and/or safe and effective antiviral chemotherapy for the woman in early gestation who is infected with a known teratogenic agent.

Mumps of the heart. Clinical and pathologic features

The clinical and pathologic findings of a patient who died from diffuse myocardial disease 8 months after an attack of mumps is presented. His illness was complicated by myocarditis, meningoencephalitis, pancreatitis, and orchitis. A study of past reports discloses that electrocardiographic evidence of myocardial involvement in mumps is common, that clinical evidence of myocardial involvement is unusual, and that death from myocardial involvement is extremely rare.

Anomalous Origin of the Left Coronary Artery from the Pulmonary Trunk with Special Reference to the Occurrence of Mitral Insufficiency

Nine cases of anomalous origin of the left coronary artery from the pulmonary trunk, involving patients ranging in age from 2 months to 7 years, have been reviewed. In six patients, mitral insufficiency was a prominent feature and, in three of these patients, mitral insufficiency presented the major problem, clinically.

Of the five patients who died, necropsy was done in four. In each, healed infarction of the posterior papillary muscles of the left ventricle was demonstrated and, in two, the anterior papillary muscles were also involved.

The clinical picture was that of an acyanotic patient with nonspecific respiratory complaints and retardation of growth. In five patients, there were symptoms (although a presenting complaint in only one) which are considered classic for this anomaly. These symptoms included episodes of pallor, dyspnea, and perspiration. Eight patients experienced cardiac failure in infancy and response to digitalis was effective in each.

In this study, endocardial fibroelastosis, without associated cardiac malformations other than mitral insufficiency, presented difficulty in the differential diagnosis. The vectorcardiogram in the horizontal plane was most helpful in the diagnosis of anomalous origin of the left coronary from the pulmonary trunk. The QRS sÊ loop in the horizontal plane in this anomaly was oriented posteriorly to the left and its direction was clockwise, in contrast to the counterclockwise direction of the loop in endocardial fibroelastosis.

Selective ascending aortography or selective right coronary arteriography established the diagnosis in seven cases.

The Diagnosis of Primary Endocardial Fibroelastosis

A comparison has been made of the clinical features of a group of autopsy-proved cases of endocardial fibroelastosis and a clinically diagnosed group with similar findings. It has been possible to make a diagnosis of endocardial fibroelastosis before death in all cases showing a characteristic clinical and electrocardiographic pattern. The characteristic features are (a) appearance of congestive heart failure; (b) absence of organic heart murmurs; (c) onset of signs or symptoms in the first 8 months of life (85 per cent) and rarely after 1½ years; (d) a period of observation under therapy during which is ruled out the conditions that simulate endocardial fibroelastosis, such as an anomalous coronary artery arising from the pulmonary artery, glycogen-storage disease, coronary artery necrosis, or myocarditis; (e) an abnormal increase in voltage of R in V 6 , S in V 1 , or both together; (f) a flat or inverted T wave in V 6 (85 per cent have a T wave 1 mm. or deeper); (g) a Q wave in V 6 (present in 60 per cent).

All the cases proved at autopsy that fulfilled these criteria during life were correctly diagnosed before death. Approximately 85 per cent of the total group were thus recognized. Fifteen per cent were not identified because electrocardiographic tracings showed an atypical right loading pattern. An occasional case with right loading may be suspected by history of a previous sibling with endocardial fibroelastosis.

Since the differential diagnosis between endocardial fibroelastosis and acute myocarditis has been considered difficult in the past, a group of infants and children with myocarditis were reviewed. The majority were proved at autopsy. Such children were also correctly diagnosed during life in most instances. The patients who were diagnosed clinically as having endocardial fibroelastosis and who survived had electrocardiographic patterns that were similar to those in the autopsy-proved group and unlike those in the myocarditis group. The chief differences were in voltages of R and S waves in precordial leads V 6 or V 1 , T waves in V 6 , and Q waves in V 6 .

Cases of endocardial fibroelastosis associated with mitral or aortic valvular disease usually had a similar age of onset or a little earlier. The electrocardiographic pattern was similar. The presence of an aortic or mitral systolic murmur made it difficult to be certain about the underlying pathology. The left loading pattern, however, with increased voltage in the pertinent precordial leads accompanied by a flat or inverted T wave in V 6 in a baby with a large heart or with congestive heart failure, provides suggestive evidence of endocardial fibroelastosis.

The contracted type of endocardial fibroelastosis reported by Edwards is a relatively rare finding. When it does occur, it may or may not be associated with a right loading pattern in the electrocardiogram. The right loading pattern in endocardial fibroelastosis is more likely to be due to heart failure with pulmonary congestion and overloading of the right ventricle, which in an infant may then overshadow the left. This pattern may revert to the more characteristic one of left loading after digitalization has been completed.

The mumps antigen skin test is proving to be a useful diagnostic tool, since it is found to be positive in primary endocardial fibroelastosis in the first 2 years of life. In our experience this occurs without a positive serum antibody reaction to mumps virus. Normal children, or those with congenital heart disease in the same age group, rarely have a positive skin reaction unless they have a recent history of mumps. Further work is needed to clarify this relationship, but on the evidence to date its diagnostic value in primary endocardial fibroelastosis shows considerable promise.