Endocardial Fibroelastosis is Secondary to Hemodynamic Alterations in the Chick Embryonic Model of Hypoplastic Left Heart Syndrome.

BACKGROUND: Endocardial fibroelastosis (EFE) is a diffuse thickening of the ventricular endocardium, causing myocardial dysfunction and presenting as unexplained heart failure in infants and children. One of the postulated causes is persistent and increased wall tension in the ventricles. RESULTS: To examine whether reduced ventricular pressure in a chick model of hypoplastic left heart syndrome (HLHS) induced by left atrial ligation (LAL) at embryonic day (ED) 4 is associated with EFE at later stages, myocardial fibrosis was evaluated by histology and immunoconfocal microscopy and mass spectrometry (MS) at ED12. Immunohistochemistry with collagen I antibody clearly showed a significant thickening of the layer of subendocardial fibrous tissue in LAL hearts, and MS proved this significant increase of collagen I. To provide further insight into pathogenesis of this increased fibroproduction, hypoxyprobe staining revealed an increased extent of hypoxic regions, normally limited to the interventricular septum, in the ventricular myocardium of LAL hearts at ED8. CONCLUSIONS: Abnormal hemodynamic loading during heart development leads to myocardial hypoxia, stimulating collagen production in the subendocardium. Therefore, EFE in this chick embryonic model of HLHS appears to be a secondary effect of abnormal hemodynamics. Developmental Dynamics 247:509-520, 2018. © 2017 Wiley Periodicals, Inc.

The myocardial and coronary histopathology and pathogenesis of hypoplastic left heart syndrome.

Hypoplastic left heart syndrome has the greatest mortality rate among all CHDs and without palliation is uniformly fatal. Despite noble efforts, the aetiology of this syndrome is unknown and a cure remains elusive. The genetic and anatomic heterogeneity of hypoplastic left heart syndrome supports a rethinking of old hypotheses and warrants further investigation into the histological and vascular variations recognised with this syndrome. In an effort to elucidate the pathogenesis of hypoplastic left heart syndrome, this review will focus on its unique myocardial and coronary pathology as well as evaluate the association of hypoplastic left heart syndrome with the endocardial fibroelastosis reaction.

Cardiac mass in Behçet's disease.

Cardiac mass is a rare manifestation of Behçet's disease (BD). Intracardiac thrombosis, endomyocardiofibrosis, endocardial fibroelastosis, inflammatory mass and cystic change have been reported as different entities of cardiac mass in BD. Here we presented 6 cases of this rare manifestation of BD. The clinical and pathological features were reviewed.

Unusual aortic valve anomaly in the fetus: a case report.

Aortic valve anomalies in fetal life usually concern aortic valve stenosis, in severe forms associated to left ventricular impairment - endocardial fibroelastosis and mitral valve insufficiency. Isolated aortic regurgitation in utero is infrequent and is usually considered to be due to a rare anomaly: aorto-left ventricular tunnel. We describe an unusual case of fetal aortic valve anomaly with severe dysplasia, with a marked regurgitant flow through the aortic valve, passing in a retrograde way from the duct, associated with a marked left ventricular endocardial fibroelastosis and dysfunction, resulting in the fatal outcome of the case.

[Advance in research on endocardial fiborelastosis].

Endocardial fiborelastosis (EFE) is a common infantile myocardiosis. The pathogenesis of EFE may be associated with viral infection, genetic factors, immune factors and endocardial dysplasia. The fundamental pathological changes of EFE include hyperplasia of endocardium elastic fibers and collagen fibers. Acute EFE is a frequent type. Clinical manifestations of EFE are non-specific and children with EFE mainly present with congestive heart failure. Echocardiography is very helpful to the diagnosis of EFE. It is necessary to differentiate EFE from pneumonia complicated by acute congestive heart failure, viral myocarditis and anomalous origin of the left coronary artery. Treatment is meant to control symptoms of congestive heart failure. Patients who respond well to digitalis and have good medication compliance have a favorable prognosis.

Refractory dilated cardiomyopathy associated with metastatic neuroblastoma.

A 2-year-old African American male presented with heart failure and an abdominal mass. Computerized tomography (CT) scan revealed a 7 cm adrenal lesion, confirmed as poorly differentiated neuroblastoma (NB). CT and meta-iodobenzoguanidine (MIBG) scans identified multiple metastases, but cardiac MIBG imaging was absent. Cardiac ejection fraction (EF) was 8% with 7% shortening fraction. The patient underwent six cycles of chemotherapy and investigational immunotherapy. Cardiac function improved to 26% EF. However, the tumor proved unresponsive to treatment. The patient died from stage IV congestive heart failure (CHF) and progressive NB. Autopsy confirmed dilated cardiomyopathy with endocardial fibroelastosis.

Flow disturbances and the development of endocardial fibroelastosis.

OBJECTIVES: Endothelial-to-mesenchymal transition (EndMT) has been identified as the underlying mechanism of endocardial fibroelastosis (EFE) formation. The purpose of this study was to determine whether hemodynamic alterations due to valvar defects promote EndMT and whether age-specific structural changes affect ventricular diastolic compliance despite extensive surgical resection of EFE tissue. MATERIAL AND METHODS: We analyzed EFE tissue from 24 patients with hypoplastic left heart syndrome (HLHS) who underwent left ventricular (LV) rehabilitation surgery at Boston Children's Hospital between December 2011 and March 2018. Six patients with flow disturbances across the aortic valve and/or mitral valve but no HLHS diagnosis and macroscopic appearance of "EFE-like tissue" in the LV were included for comparison. All samples were examined for amount of collagen/elastin production and degradation, and presence of active EndMT by histologic analysis. RESULTS: EFE tissue from patients with and without HLHS consisted predominantly of elastin and collagen fibers. There was no alteration in degradation activity for collagen or elastin as shown by in situ zymography. Active EndMT was found in all patients with and without HLHS with flow disturbances ("EFE-like"). In patients with HLHS, EFE infiltrated into the underlying myocardium with increasing age. CONCLUSIONS: Patients with and without HLHS with flow disturbances due to stenotic or incompetent valves develop EndMT-derived fibrotic tissue covering the LV. When EFE recurs, it is directly associated with flow disturbances and switches to an infiltrative growth pattern with increasing age, leading to increased diastolic stiffness of the LV.

Dilated cardiomyopathy with endocardial fibroelastosis in a juvenile Pallas cat.

Dilated cardiomyopathy (DCM) is a myocardial disease characterized by ventricular chamber dilation associated with systolic myocardial dysfunction in the absence of other cardiac lesions. DCM occasionally develops in conjunction with proliferation of fibroelastic fibers in the endocardium, producing endocardial fibroelastosis (EFE). Although early reports describe EFE as a primary disease, evidence now suggests that EFE may develop as a response to myocardial dysfunction. Echocardiographic evaluation of a 4-wk-old Pallas cat ( Otocolobus manul) with respiratory distress revealed enlargement of both atria, enlarged end-systolic left ventricular dimension, and left ventricular dilation. DCM was diagnosed, and the cat was euthanized, given the poor prognosis. Postmortem examination revealed pericardial effusion and biventricular and biatrial enlargement. The interventricular septum and free walls of ventricles were thin. Histologically, the endocardium of the left and right ventricles was diffusely thickened; Verhoeff-Van Gieson staining of the left ventricular endocardium revealed a moderate amount of endocardial accumulation of elastin and collagen. These fibers were more prominent in papillary muscles and around coronary blood vessels. Based on these findings, we diagnosed DCM with EFE. Cardiac diseases are rarely diagnosed in wild felids.

Primary endocardial fibroelastosis with dilated cardiomyopathy: report of one case.

We report a case of dilated cardiomyopathy presented in a premature infant of 27 weeks' gestational age. A prenatal sonography revealed left ventricular enlargement. The infant presented with respiratory distress and heart failure soon after birth. Echocardiograms performed after birth showed dilated cardiomyopathy, and endocardial fibroelastosis was suspected. Heart failure progressed despite administration of inotropic agents. The infant died after fifteen days from circulatory failure. Postmortem examination confirmed the diagnosis of endocardial fibroelastosis.

Left heart growth, function, and reintervention after balloon aortic valvuloplasty for neonatal aortic stenosis.

BACKGROUND: Transcatheter balloon aortic valvuloplasty (BAVP) has become the first-line treatment for critical aortic stenosis (AS) in neonates. However, little is known about the growth and function of left heart structures or about patterns of reintervention on the left heart after neonatal BAVP. METHODS AND RESULTS: Between 1985 and 2002, 113 patients underwent neonatal BAVP at < or =60 days of age. There were 16 early deaths (14%), with a significant decrease from 1985 to 1993 (22%) to 1994 to 2002 (4%), and 6 patients had successful early conversion to a univentricular circulation. In the short term, the mean relative gradient reduction was 54+/-26%, and significant aortic regurgitation (AR) developed in 15% of patients. The 91 early survivors with a biventricular circulation were followed up for 6.3+/-5.3 years, during which time there was a steady increase in the frequency of significant AR. Freedom from moderate or severe AR was 65% at 5 years. In almost all patients with a baseline aortic annulus z score less than -1, the annulus diameter increased to within the normal range within 1 to 2 years. Similarly, left ventricular (LV) end-diastolic dimension z scores, which ranged from -5 to 7.5 before BAVP, normalized within 1 to 2 years in nearly all patients with a predilation z score less than -1. Among early survivors with a biventricular circulation, reintervention-free survival on the LV outflow tract was 65% at 1 year and 48% at 5 years, with younger age, higher pre- and post-BAVP gradients, and a larger balloon-annulus diameter ratio associated with decreased reintervention-free survival (P<0.01). Seventeen surgical interventions were performed on the aortic valve in 15 patients, including replacement in 7. Survival free from aortic valve replacement was 84% at 5 years. CONCLUSIONS: BAVP for AS during the first 60 days of life results in short-term relief of AS in the majority of patients. Among early survivors, initially small left heart structures may be associated with worse subacute outcomes but typically normalize within 1 year. Reintervention for residual/recurrent AS or iatrogenic AR is relatively common, particularly during the first year after BAVP, but aortic valve replacement during early childhood is seldom necessary.

Usefulness of magnetic resonance imaging of left ventricular endocardial fibroelastosis in infants after fetal intervention for aortic valve stenosis.

This report describes the use of myocardial delayed-enhancement magnetic resonance imaging to delineate the extent of endocardial fibroelastosis (EFE) in 4 infants after fetal balloon aortic valvuloplasty. The preoperative mapping of EFE followed by extensive resection led to biventricular physiology in 2 patients.

A mouse model of endocardial fibroelastosis.

BACKGROUND: Endocardial fibroelastosis (EFE) is a pathologic condition of abnormal deposition of collagen and elastin within the endocardium of the heart. It is seen in conjunction with a variety of diseases including hypoplastic left heart syndrome and viral endocarditis. While an experimental model using heterotopic heart transplant in rats has been described, we sought to fully describe a mouse model that can be used to further elucidate the potential mechanisms of and treatments for EFE. MATERIALS AND METHODS: The hearts of 2-day-old C57BL/6 mice were transplanted into the abdomen of 7-week-old C57BL/6 mice. At 2 weeks, the hearts were harvested and histologic analysis was performed using hematoxylin and eosin, Masson's trichrome, Russell-Movat's pentachrome, Picrosirius red, Hart's, Verhoeff-Van Gieson, and Weigert's Resorcin-Fuchsin stains. Additionally, one heart was analyzed using transmission electron microscopy (TEM). RESULTS: Specimens demonstrated abnormal accumulation of both collagen and elastin within the endocardium with occasional expansion into the myocardium. Heterogeneity in extracellular matrix deposition was noted in the histologic specimens. In addition, TEM demonstrated the presence of excess collagen within the endocardium. CONCLUSIONS: The heterotopic transplantation of an immature heart into a mouse results in changes consistent with EFE. This model is appropriate to investigate the etiology and treatment of EFE.

Familial nonobstructive cardiomyopathy with endocardial fibroelastosis beyond infancy.

A 10-year-old boy with congestive heart failure died in five months in spite of comprehensive medical treatment. Autopsy showed patchy areas of endocardial fibroelastosis of the left ventricle. The sister of this patient had followed a similar course at 13 years of age with death within six months of the onset of congestive failure. Her postmortem examination also showed endocardial fibroelastosis. The clinical presentation of familial endocardial fibroelastosis in the preteen and teenage years is a rare event. Probably the endocardial fibroelastosis was secondary to a familial nonobstructive cardiomyopathy.

Sequelae of atriotomy and ventriculotomy on the endocardium, conduction system and coronary arteries.

The endocardium was analyzed in all four chambers of 99 hearts with various types of congenital heart defects in which surgical repair was performed more than 6 weeks before death. The findings were compared with those of normal hearts in similar age groups. In some cases the endocardium was microscopically examined. This study revealed that in many cases all four chambers had fibroelastosis of the endocardium (diffuse regardless of the type of surgery done previously). These data suggest that diffuse fibroelastosis can occur as a result of surgical intervention and may be related to blocked lymphatic drainage. Sudden death in some patients long after surgery for congenital heart disease and the failure of the chambers to regress to normal size in some cases after total surgical repair may be related to fibroelastosis of the chambers. The sinoatrial node may be injured in atriotomy and in the performance of the Mustard procedure. Ventriculotomy may injure the right bundle branch. Ventriculotomy may also injure the coronary supply to the right ventricle or rarely the anterior descending coronary artery.

Endocardial fibroelastosis and myocardial calcification secondary to an anomalous right coronary artery arising from the pulmonary trunk.

The case of an infant with endocardial fibroelastosis and a coexistent anomalous right coronary artery that originated from the pulmonary trunk is presented. The causal relation between the two conditions is discussed.

Restrictive cardiomyopathy in pseudoxanthoma elasticum.

A unique case of severe and diffuse endocardial fibroelastosis covering the entire left ventricle and associated with pseudoxanthoma elasticum is presented. The clinical picture was that of an apparently primary restrictive cardiomyopathy. Specific histologic lesions could be recognized in the endocardium.

Endocardial fibroelastosis in infants with hydrops fetalis.

Endocardial fibroelastosis, defined as an endocardium in excess of 30 microns thick, was found in 10 out of 34 cases of hydrops fetalis in a review of 1589 perinatal necropsies carried out between 1976 and 1989. The infants comprised 16 cases of rhesus haemolytic disease, of whom three had endocardial fibroelastosis, and 18 cases of non-rhesus hydrops, of whom seven had endocardial fibroelastosis. Intrauterine congestive heart failure was thought to have been the probable cause of hydrops in eight of the 10 infants with endocardial fibroelastosis. None of an age matched control group without endocardial fibroelastosis had evidence of congestive cardiac failure. These observations support the hypothesis that endocardial fibroelastosis is an endocardial response to chronic prenatal myocardial stress.

Fetal echocardiographic signs of congenital endocardial fibroelastosis.

Endocardial fibroelastosis is characterized by a porcelain-like thickening of the endocardium, resulting in a marked increase in echodensity of the endocardium, as well as ventricular dilatation and aortic atresia. With improvement in prenatal ultrasound, this condition can be suspected in utero on the basis of ventricular enlargement, poor ventricular contractility, and marked echodensity of the endocardial surface. We present two cases in which such conditions were found on prenatal M-mode echocardiography and two-dimensional directed pulsed Doppler. Ventriculomegaly and hypocontractility of the ventricle are, however, nonspecific for such conditions; the diagnosis can be made accurately only by pathology. When such findings appear on ultrasound, all efforts should be made to deliver the patient in a perinatal center for optimal neonatal surgery to improve the survival of the newborn.