Intracranial calcifications simulating Aicardi-Goutières syndrome in PARS2-related mitochondrial disease

PARS2 encodes an aminoacyl-tRNA synthetase that catalyzes the ligation of proline to mitochondrial prolyl-tRNA molecules. Diseases associated with PARS2 primarily affect the central nervous system, causing early infantile developmental epileptic encephalopathies (EIDEE; DEE75; MIM #618437) with infantile-onset neurodegeneration. Dilated cardiomyopathy has also been reported in the affected individuals. About 10 individuals to date have been described with pathogenic biallelic variants in PARS2. While many of the reported individuals succumbed to the disease in the first two decades of life, autopsy findings have not yet been reported. Here, we describe neuropathological findings in a deceased male with evidence of intracranial calcifications in the basal ganglia, thalamus, cerebellum, and white matter, similar to Aicardi-Goutières syndrome. This report describes detailed autopsy findings in a child with PARS2-related mitochondrial disease and provides plausible evidence that intracranial calcifications may be a previously unrecognized feature of this disorder.

Atypical infiltrates on endomyocardial biopsy are associated with adverse outcomes in pediatric heart transplantation

BACKGROUND

The significance of atypical infiltrates (eosinophils or plasma cells) on endomyocardial biopsy (EMB) after pediatric heart transplant (HTx) is not known. We hypothesized that atypical infiltrates are associated with worse post-HTx outcomes.

METHODS

We performed a retrospective cohort study of consecutive patients <21 years old who underwent primary HTx between 2013 and 2017. Multiorgan transplants were excluded. The presence of atypical infiltrates and burden of atypical infiltrates (rare vs predominant) on EMB were recorded. Primary outcome was a composite of cardiac allograft vasculopathy, graft failure (relisting or retransplant), or death. Presence of atypical infiltrates was evaluated: (1) overall using Cox regression with time-dependent covariates and (2) if present by 1 year post-HTx using Kaplan-Meier analysis.

RESULTS

Atypical infiltrates were present in 24 out of 95 patients (25%) and were associated with a higher likelihood of reaching the composite outcome (hazard ratio (HR) 6.22, 95% confidence interval (CI) 2.60-14.89, p < 0.0001). This persisted when controlling for rejection in multivariable analysis. There was also a greater risk of the composite outcome if ≥2 nonconsecutive EMBs had atypical infiltrates (HR 11.80, 95%CI 3.17-43.84, p = 0.0002) or if atypical infiltrates were the predominant feature on EMB (HR 30.58, 95%CI 9.34-100.06, p < 0.0001). Patients with atypical infiltrates by 1-year post-HTx had a 5-year freedom from the composite outcome of 48%, compared to 90% if no atypical infiltrates had been present by this timepoint (log rank p = 0.002).

CONCLUSIONS

The presence of atypical infiltrates on EMB is associated with significantly worse outcomes in children following HTx. These patients require closer follow-up to assess for developing graft dysfunction.

The Many Faces of Arrhythmogenic Cardiomyopathy: An Overview

Arrhythmogenic cardiomyopathy (AC) is a disease that involves electromechanical uncoupling of cardiomyocytes. This leads to characteristic histologic changes that ultimately lead to the arrhythmogenic clinical features of the disease. Initially thought to affect the right ventricle predominantly, more recent data show that it can affect both the ventricles or the left ventricle alone. Throughout the recent era, diagnostic modalities and criteria for AC have continued to evolve and our understanding of its clinical features in different age groups as well as the genotype to the phenotype correlations have improved. In this review, we set out to detail the epidemiology, etiologies, presentations, evaluation, and management of AC across the age continuum.

In Utero Presentation of Left Ventricular Aneurysm

Congenital left ventricular aneurysm, pseudoaneurysm, and diverticulum are rare entities. These diagnoses can be made pre- and/or postnatally. Although these entities overlap clinically and morphologically, important distinctions can allow for accurate diagnoses. Appropriate diagnosis can be imperative for risk stratification and guidance of prenatal and postnatal management. The case described in the present report highlights a challenging case of a fetal left ventricular aneurysm, management during the prenatal and postnatal periods, and important differentiating features from a ventricular diverticulum and pseudoaneurysm.

Arrhythmogenic cardiomyopathy is under-recognized in end-stage pediatric heart failure: A 36-year single-center experience

BACKGROUND

Although ventricular failure is a late finding in adults with AC, we hypothesize that this is a presenting symptom in pediatric heart failure patients who undergo HT and that their ventricular arrhythmia burden could differentiate AC from other cardiomyopathies.

METHODS

We performed a single-center retrospective cohort study reviewing 457 consecutive pediatric (≤18 years) HT recipients at our institution. Explanted hearts were examined to establish the primary diagnosis, based on pathologic findings. Demographic and clinical variables were compared between AC versus non-HCM cardiomyopathy cases.

RESULTS

Forty-five percent (n = 205/457) had non-HCM cardiomyopathies as the underlying primary diagnosis. Ten cases (10/205 = 4.9%) were diagnosed with AC. All 10 had biventricular disease. In 8/10 patients (80%), AC diagnosis was unrecognized pre-HT. Compared with non-AC cardiomyopathies, the AC group was older at diagnosis (9.3 years vs. 4.3 years, p = .012) and transplant (11.1 years vs. 6.5 years, p = .010), had more ventricular arrhythmias (80.0% vs 32.8%, p = .003), and required more anti-arrhythmic use (80.0% vs 32.3%, p = .001). Genetic testing yielded causative pathogenic variants in all tested individuals (n = 5/5, 100%).

CONCLUSION

AC is often an unrecognized cardiomyopathy pretransplant in children who undergo HT. Pediatric non-HCM phenotypes with heart failure who have a significant ventricular arrhythmia burden should be investigated for AC.

Forme Fruste Cor Triatriatum Dexter by Transesophageal Echocardiography and Its Impact on Percutaneous Heart Procedures: A Case Series

•

Cor triatriatum dexter (CTD) can complicate percutaneous atrial septal interventions.

•

Clinically silent (forme fruste) CTD is detectable by new echocardiography techniques.

•

Using these techniques could improve patient selection and guide interventions.

A 14-year-old in heart failure with multiple cardiomyopathy variants illustrates a role for signal-to-noise analysis in gene test re-interpretation

Variants of unknown significance in cardiomyopathic disease should be analyzed systematically based on the prevalence of the variant in the population compared to prevalence of disease, evidence that other variants in the gene are pathologic, consistency of prediction software on pathogenicity, and the current clinical consensus.

Acute humoral rejection in an infant without risk factors after heart transplantation

Graft rejection is the most common factor that limits graft survival after transplantation. During infancy, the humoral immune system is partially suppressed and humoral rejection of a cardiac allograft has not been reported in the absence of risk factors such as prior transplantation, blood transfusions, ventricular assist devices, and elevation of panel reactive antibodies. We present a case of an infant with dilated cardiomyopathy who developed multiple episodes of acute humoral rejection after heart transplantation in the absence of risk factors.

Narrowing the FOXF1 distant enhancer region on 16q24.1 critical for ACDMPV

Background

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a rare lethal lung developmental disorder caused by heterozygous point mutations or genomic deletions involving FOXF1 or its 60-kb tissue-specific enhancer region mapping 270 kb upstream of FOXF1 and involving fetal lung-expressed long non-coding RNA genes and CpG-enriched sites. Recently, we have proposed that the FOXF1 locus at 16q24.1 may be a subject of genomic imprinting.

Findings

Using custom-designed aCGH and Sanger sequencing, we have identified a novel de novo 104 kb genomic deletion upstream of FOXF1 in a patient with histopathologically verified full phenotype of ACDMPV. This deletion allowed us to further narrow the FOXF1 enhancer region and identify its critical 15-kb core interval, essential for lung development. This interval harbors binding sites for lung-expressed transcription factors, including GATA3, ESR1, and YY1, and is flanked by the lncRNA genes and CpG islands. Bisulfite sequencing of one of these CpG islands on the non-deleted allele showed that it is predominantly methylated on the maternal chromosome 16.

Conclusions

Substantial narrowing and bisulfite sequencing of the FOXF1 enhancer region on 16q24.1 provided new insights into its regulatory function and genomic imprinting.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-016-0278-2) contains supplementary material, which is available to authorized users.

Pre-cannulation lung biopsy shortens ECMO course

We describe the clinical course of an infant with respiratory failure who underwent lung biopsy prior to cannulation for undergoing extracorporeal membrane oxygenation (ECMO). Pathology revealed alveolar capillary dysplasia, and ECMO was discontinued. Rapid diagnosis allowed for closure and saved resources. We recommend considering early biopsy in infants with atypical pulmonary hypertension.

Green tea extract: A potential cause of acute liver failure

The use of herbal products has increased significantly in recent years. Because these products are not subject to regulation by the Food and Drug Administration and are often used without supervision by a healthcare provider, the indication for and consumption of these supplements is quite variable. Moreover, their use is generally regarded as safe and natural by the lay-public. Unfortunately, there has been an increase in the number of reported adverse events occurring with the use of herbal products. We present a case of acute impending liver failure in an adolescent male using a weight-loss product containing green tea extract. Our case adds to the growing concern surrounding the ingestion of green tea extract and serves to heighten healthcare provider awareness of a potential green tea extract hepatotoxicity. Despite the generally touted benefits of green tea as a whole, clinical concern regarding its use is emerging and has been linked to its concentration in multiple herbal supplements. Interestingly, the suspected harmful compounds are those previously proposed to be advantageous for weight-loss, cancer remedy, and anti-inflammatory purposes. Yet, we emphasize the need to be aware of not just green tea extract, but the importance of monitoring patient use of all dietary supplements and herbal products.

The Pathological Spectrum of Left-Ventricular Hypoplasia

Left-ventricular (LV) hypoplasia encompasses a range of LV sizes, varying from a mildly underdeveloped, but functionally adequate, chamber to the miniscule, barely perceptible LV cavity seen in hypoplastic left-heart syndrome. Associated malformations include obstructive lesions of LV inflow, outflow, and the aortic arch, often in combination. Repair of complex combinations and/or severe LV hypoplasia usually results in a single-ventricle anatomy with the right ventricle serving as the systemic ventricle. New therapeutic interventions, including fetal procedures, are expanding the spectrum of lesions and LV sizes that may be amenable to a biventricular repair. These surgical considerations place renewed emphasis on understanding the anatomical features associated with LV hypoplasia. This review details pathological features of the full spectrum of LV hypoplasia, particularly those with borderline severe hypoplasia. Primary defining lesions are described as well as additional lesions that may affect clinical symptoms, surgical repair, and long-term outcome.

Molecular basis for clinical heterogeneity in inherited cardiomyopathies due to myopalladin mutations

Abnormalities in Z-disc proteins cause hypertrophic (HCM), dilated (DCM) and/or restrictive cardiomyopathy (RCM), but disease-causing mechanisms are not fully understood. Myopalladin (MYPN) is a Z-disc protein expressed in striated muscle and functions as a structural, signaling and gene expression regulating molecule in response to muscle stress. MYPN was genetically screened in 900 patients with HCM, DCM and RCM, and disease-causing mechanisms were investigated using comparative immunohistochemical analysis of the patient myocardium and neonatal rat cardiomyocytes expressing mutant MYPN. Cardiac-restricted transgenic (Tg) mice were generated and protein-protein interactions were evaluated. Two nonsense and 13 missense MYPN variants were identified in subjects with DCM, HCM and RCM with the average cardiomyopathy prevalence of 1.66%. Functional studies were performed on two variants (Q529X and Y20C) associated with variable clinical phenotypes. Humans carrying the Y20C-MYPN variant developed HCM or DCM, whereas Q529X-MYPN was found in familial RCM. Disturbed myofibrillogenesis with disruption of α-actinin2, desmin and cardiac ankyrin repeat protein (CARP) was evident in rat cardiomyocytes expressing MYPN(Q529X). Cardiac-restricted MYPN(Y20C) Tg mice developed HCM and disrupted intercalated discs, with disturbed expression of desmin, desmoplakin, connexin43 and vinculin being evident. Failed nuclear translocation and reduced binding of Y20C-MYPN to CARP were demonstrated using in vitro and in vivo systems. MYPN mutations cause various forms of cardiomyopathy via different protein-protein interactions. Q529X-MYPN causes RCM via disturbed myofibrillogenesis, whereas Y20C-MYPN perturbs MYPN nuclear shuttling and leads to abnormal assembly of terminal Z-disc within the cardiac transitional junction and intercalated disc.

Thrombotic microangiopathic hemolytic anemia with reduction of ADAMTS13 activity: initial manifestation of childhood-onset systemic lupus erythematosus

Severe manifestations of systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), and thrombotic thrombocytopenic purpura (TTP) are characterized by multiorgan thrombotic microangiopathy. We describe reduction of ADAMTS13 activity and the development of systemic autoimmunity in all 8 children initially diagnosed with acquired noncongenital TTP during an 8.5-year period. Median age at diagnosis was 12.0 years (range, 2.6-17.3 years). ADAMTS13 activity was absent (<5%) in 6 patients; 3 patients had a detected inhibitor. SLE was diagnosed concurrently in 3 patients, and 4 patients were diagnosed within 5 years. Six of the children diagnosed with SLE had absent ADAMTS13 activity at diagnosis. In 6 patients with SLE, immune-mediated nephritis developed by 46 months. All surviving patients with SLE developed antiphospholipid antibodies, including some with a lupus anticoagulant. Patients with SLE did not have TTP recurrences once daily immunosuppressive regimens were started. An evaluation for SLE/APS is warranted in children and adolescents with reduced ADAMTS13 activity and thrombotic microangiopathy.

Insight into pathologic abnormalities in congenital semilunar valve disease based on advances in understanding normal valve microstructure and extracellular matrix

Congenitally diseased valves are relatively frequent causes of significant morbidity and mortality. Pathology descriptions of such valves have primarily focused on gross structural features including the number of leaflets or commissures (bicuspid/bicommissural valve) and alterations in the contour, thickness, and consistency of the leaflets (dysplastic valve). Functional correlates of these pathologic alterations are valvar stenosis, insufficiency, or both. Further characterization of the microstructural abnormalities seen in these malformed valves may not only provide insight into the correlation of distinct pathologies with their respective pathogenesis and clinical sequelae but also prove pivotal in uncovering new avenues for therapeutic interventions and prevention regimens. This review summarizes microstructural findings in congenital semilunar valve disease (CSVD) and discusses their relevance in light of recent advances in knowledge of normal valve microstructure, biology, and function. Specifically, the biological and mechanical roles of various matrix components and their interactions are discussed in the context of CSVD. Indeed, recent research in normal valves adds significant insight into CSVD and raises many hypotheses that will need to be addressed by future studies.

Nebulette mutations are associated with dilated cardiomyopathy and endocardial fibroelastosis

OBJECTIVES

Four variants (K60N, Q128R, G202R, and A592E) in the nebulette gene were identified in patients with dilated cardiomyopathy (DCM) and endocardial fibroelastosis. We sought to determine if these mutations are cardiomyopathy causing.

BACKGROUND

Nebulette aligns thin filaments and connects them with the myocardial Z-disk, playing a role in mechanosensation.

METHODS

We generated transgenic mice with cardiac-restricted overexpression of human wild-type or mutant nebulette. Chimera and transgenic mice were examined at 4, 6, and 12 months of age by echocardiography and cardiac magnetic resonance imaging. The hearts from embryos and adult mice were assessed by histopathologic, immunohistochemical, ultrastructural, and protein analyses. Rat H9C2 cardiomyoblasts with transient expression of nebulette underwent cyclic mechanical strain.

RESULTS

We identified lethal cardiac structural abnormalities in mutant embryonic hearts (K60N and Q128R). Founders of the mutant mouse lines developed DCM with severe heart failure. An irregular localization pattern for nebulette and impaired desmin expression were noted in the proband and chimeric Q128R mice. Mutant G202R and A592E mice exhibited left ventricular dilation and impaired function with specific changes in I-band and Z-disk proteins by 6 months of age. The mutations modulated distribution of nebulette in the sarcomere and Z-disk during stretch of H9C2 cells.

CONCLUSIONS

Nebulette is a new susceptibility gene for endocardial fibroelastosis and DCM. Different mutations in nebulette trigger specific mechanisms, converging to a common pathological cascade leading to endocardial fibroelastosis and DCM.

Extracellular matrix remodeling and cell phenotypic changes in dysplastic and hemodynamically altered semilunar human cardiac valves

INTRODUCTION

Congenital cardiac valve disease is common, affecting ∼1% of the population, with substantial morbidity and mortality, but suboptimal treatment options. Characterization of the specific matrix and valve cell phenotypic abnormalities in these valves could lend insight into disease pathogenesis and potentially pave the way for novel therapies.

METHODS

Thirty-five human aortic and pulmonic valves were categorized based on gross and microscopic assessment into control valves (n=21); dysplastic valves, all except one also displaying hemodynamic changes (HEMO/DYSP, n=6); and hemodynamically altered valves (HEMO, n=8). Immunohistochemistry was performed on valve sections and flow cytometry on valvular interstitial cells.

RESULTS

While both hemodynamically altered aortic and pulmonic valves demonstrated increased collagen turnover and cell activation, prolyl 4-hydroxylase and hyaluronan increased in hemodynamically altered aortic valves but decreased in hemodynamically altered pulmonic valves relative to control valves (P<.001). HEMO/DYSP aortic valves demonstrated decreased collagen and elastic fiber synthesis and turnover compared to both hemodynamically altered aortic valves and control aortic valves (each P<.006). Valvular interstitial cells from both hemodynamically altered and HEMO/DYSP pulmonic valves showed altered cell phenotype compared to control valves (each P<.032), especially increased non-muscle myosin. Furthermore, valvular interstitial cells from hemodynamically altered pulmonic valves and HEMO/DYSP aortic and pulmonic valves each demonstrated greater size and complexity compared to control valves (each P<.05).

CONCLUSIONS

Dysplastic semilunar valves displayed alterations in collagen and elastic fiber turnover that were distinct from valves similarly exposed to altered hemodynamics as well as to control valves. These results demonstrate that dysplastic valves are not simply valves with gross changes or loss of leaflet layers, but contain complex matrix and cell phenotype changes that, with future study, could potentially be targets for novel nonsurgical treatments.

Viral epidemiologic shift in inflammatory heart disease: the increasing involvement of parvovirus B19 in the myocardium of pediatric cardiac transplant patients

BACKGROUND

Detection of viral genome in rejecting cardiac transplant patients has been reported, with coxsackievirus and adenovirus causing premature graft failure. Recently, parvovirus B19 (PVB19) genome in myocardial samples has been increasingly reported, but its role in cardiac pathology and effect on transplant graft survival are unknown. The objectives of this study were to determine if changes in the viruses identified in the myocardium represent an epidemiologic shift in viral myocardial disease and whether PVB19 adversely affects transplant graft survival.

METHODS

From September 2002 to December 2005, nested polymerase chain reaction was used to evaluate endomyocardial biopsy specimens for 99 children (aged 3 weeks-18 years) with heart transplants for the presence of viral genome. Cellular rejection was assessed by histology of specimens. Transplant coronary artery disease (TCAD) was diagnosed by coronary angiography or histopathology.

RESULTS

Specimens from 700 biopsies were evaluated from 99 patients; 121 specimens had viral genome, with 100 (82.6%) positive for PVB19, 24 for Epstein-Barr virus (EBV; 7 positive for PVB19 and EBV), 3 for CMV, and 1 for adenovirus. Presence of PVB19 genome did not correlate with rejection score, nor did a higher viral copy number. Early development of advanced TCAD (p < 0.001) occurred in 20 children with persistent PVB19 infection (> 6 months).

CONCLUSIONS

PVB19 is currently the predominant virus detected in heart transplant surveillance biopsy specimens, possibly representing an epidemiologic shift. Cellular rejection does not correlate with the presence or quantity of PVB19 genome in the myocardium, but children with chronic PVB19 infection have increased risk for earlier TCAD, supporting the hypothesis that PVB19 negatively affects graft survival.

Congenital aneurysm of the muscular interventricular septum

Congenital aneurysms of the muscular interventricular septum are rare. We report the diagnosis of such an aneurysm by fetal echocardiography at 19 weeks' gestation and the subsequent follow-up through early neonatal life, with the ultimate progression to a dilated cardiomyopathy requiring cardiac transplantation. This case highlights the early diagnosis of this rare finding and the unusual clinical course to include the confounding features of endocardial fibroelastosis, left ventricular noncompaction, and a lymphocytic infiltrate demonstrated on pathologic examination. Most infants with congenital septal aneurysms are asymptomatic, but this case demonstrates the need for careful serial assessment and clinical follow-up because of the unclear origin and natural history of this entity.

Elevation of RNA-binding protein CUGBP1 is an early event in an inducible heart-specific mouse model of myotonic dystrophy

Myotonic dystrophy type 1 (DM1) is caused by a CTG trinucleotide expansion in the 3' untranslated region (3' UTR) of DM protein kinase (DMPK). The key feature of DM1 pathogenesis is nuclear accumulation of RNA, which causes aberrant alternative splicing of specific pre-mRNAs by altering the functions of CUG-binding proteins (CUGBPs). Cardiac involvement occurs in more than 80% of individuals with DM1 and is responsible for up to 30% of disease-related deaths. We have generated an inducible and heart-specific DM1 mouse model expressing expanded CUG RNA in the context of DMPK 3' UTR that recapitulated pathological and molecular features of DM1 including dilated cardiomyopathy, arrhythmias, systolic and diastolic dysfunction, and mis-regulated alternative splicing. Combined in situ hybridization and immunofluorescent staining for CUGBP1 and CUGBP2, the 2 CUGBP1 and ETR-3 like factor (CELF) proteins expressed in heart, demonstrated elevated protein levels specifically in nuclei containing foci of CUG repeat RNA. A time-course study demonstrated that colocalization of MBNL1 with RNA foci and increased CUGBP1 occurred within hours of induced expression of CUG repeat RNA and coincided with reversion to embryonic splicing patterns. These results indicate that CUGBP1 upregulation is an early and primary response to expression of CUG repeat RNA.

Desmosomal dysfunction due to mutations in desmoplakin causes arrhythmogenic right ventricular dysplasia/cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is characterized by progressive degeneration of the right ventricular myocardium, ventricular arrhythmias, fibrous-fatty replacement, and increased risk of sudden death. Mutations in 6 genes, including 4 encoding desmosomal proteins (Junctional plakoglobin (JUP), Desmoplakin (DSP), Plakophilin 2, and Desmoglein 2), have been identified in patients with ARVD/C. Mutation analysis of 66 probands identified 4 variants in DSP; V30M, Q90R, W233X, and R2834H. To establish a cause and effect relationship between those DSP missense mutations and ARVD/C, we performed in vitro and in vivo analyses of the mutated proteins. Unlike wild-type (WT) DSP, the N-terminal mutants (V30M and Q90R) failed to localize to the cell membrane in desomosome-forming cell line and failed to bind to and coimmunoprecipitate JUP. Multiple attempts to generate N-terminal DSP (V30M and Q90R) cardiac-specific transgenes have failed: analysis of embryos revealed evidence of profound ventricular dilation, which likely resulted in embryonic lethality. We were able to develop transgenic (Tg) mice with cardiac-restricted overexpression of the C-terminal mutant (R2834H) or WT DSP. Whereas mice overexpressing WT DSP had no detectable histologic, morphological, or functional cardiac changes, the R2834H-Tg mice had increased cardiomyocyte apoptosis, cardiac fibrosis, and lipid accumulation, along with ventricular enlargement and cardiac dysfunction in both ventricles. These mice also displayed interruption of DSP-desmin interaction at intercalated discs (IDs) and marked ultra-structural changes of IDs. These data suggest DSP expression in cardiomyocytes is crucial for maintaining cardiac tissue integrity, and DSP abnormalities result in ARVD/C by cardiomyocyte death, changes in lipid metabolism, and defects in cardiac development.

Mice with the R176Q cardiac ryanodine receptor mutation exhibit catecholamine-induced ventricular tachycardia and cardiomyopathy

Mutations in the cardiac ryanodine receptor 2 (RyR2) have been associated with catecholaminergic polymorphic ventricular tachycardia and a form of arrhythmogenic right ventricular dysplasia. To study the relationship between RyR2 function and these phenotypes, we developed knockin mice with the human disease-associated RyR2 mutation R176Q. Histologic analysis of hearts from RyR2(R176Q/+) mice revealed no evidence of fibrofatty infiltration or structural abnormalities characteristic of arrhythmogenic right ventricular dysplasia, but right ventricular end-diastolic volume was decreased in RyR2(R176Q/+) mice compared with controls, indicating subtle functional impairment due to the presence of a single mutant allele. Ventricular tachycardia (VT) was observed after caffeine and epinephrine injection in RyR2(R176Q/+), but not in WT, mice. Intracardiac electrophysiology studies with programmed stimulation also elicited VT in RyR2(R176Q/+) mice. Isoproterenol administration during programmed stimulation increased both the number and duration of VT episodes in RyR2(R176Q/+) mice, but not in controls. Isolated cardiomyocytes from RyR2(R176Q/+) mice exhibited a higher incidence of spontaneous Ca(2+) oscillations in the absence and presence of isoproterenol compared with controls. Our results suggest that the R176Q mutation in RyR2 predisposes the heart to catecholamine-induced oscillatory calcium-release events that trigger a calcium-dependent ventricular arrhythmia.

Functional and clinical characterization of a mutation in KCNJ2 associated with Andersen-Tawil syndrome

BACKGROUND

Andersen-Tawil syndrome (ATS) is a rare inherited disorder, characterised by periodic paralysis, cardiac dysarrhythmias, and dysmorphic features, and is caused by mutations in the gene KCNJ2, which encodes the inward rectifier potassium channel, Kir2.1. This study sought to analyse KCNJ2 in patients with familial ATS and to determine the functional characteristics of the mutated gene.

METHODS AND RESULTS

We screened a family with inherited ATS for the mutation in KCNJ2, using direct DNA sequencing. A missense mutation (T75R) of Kir2.1, located in the highly conserved cytoplasmic N-terminal domain, was identified in three affected members of this family. Using the Xenopus oocyte expression system and whole cell voltage clamp analyses, we found that the T75R mutant was non-functional and possessed a strong dominant negative effect when co-expressed with the same amount of wild type Kir2.1. Transgenic (Tg) mice expressing the mutated form of Kir2.1 in the heart had prolonged QTc intervals compared with mice expressing the wild type protein. Ventricular tachyarrhythmias were observed in 5 of 14 T75R-Tg mice compared with 1 of 7 Wt-Tg and none of 6 non-transgenic littermates. In three of five T75R-Tg mice with ventricular tachycardia, their ECG disclosed bidirectional tachycardia as in our proband.

CONCLUSIONS

The in vitro studies revealed that the T75R mutant of Kir2.1 had a strong dominant negative effect in the Xenopus oocyte expression system. It still preserved the ability to co-assemble and traffic to the cell membrane in mammalian cells. For in vivo studies, the T75R-Tg mice had bidirectional ventricular tachycardia after induction and longer QT intervals.

Severe supravalvar aortic stenosis in familial homozygous hypercholesterolemia

Familial homozygous hypercholesterolemia is a rare disease with diverse clinical presentations. Patients often present with cutaneous xanthomas, particularly in the Achilles' tendon. They may have significant cardiovascular involvement, including premature atherosclerotic coronary artery disease and valvar and supravalvar aortic stenosis. Standard therapy includes diet modulation, pharmacotherapy, and lipid apheresis. Rarely, patients require surgical intervention for coronary artery bypass grafting and/or relief of the aortic stenosis. We present the case of a patient with severe progressive supravalvar aortic stenosis that ultimately required surgical resection despite aggressive medical therapy.

Danon disease as an underrecognized cause of hypertrophic cardiomyopathy in children

BACKGROUND

Some patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy also present with skeletal myopathy and Wolff-Parkinson-White (WPW) syndrome; mutations in the gene encoding the lysosome-associated protein-2 (LAMP-2) have been identified in these patients, suggesting that some of these patients have Danon disease. In this study we investigated the frequency of LAMP2 mutations in an unselected pediatric HCM population.

METHODS AND RESULTS

LAMP2 was amplified from genomic DNA isolated from peripheral lymphocytes of 50 patients diagnosed with HCM and analyzed by direct DNA sequencing. In 2 of the 50 probands (4%), nonsense mutations were identified. In 1 family the proband initially presented with HCM as a teenager, which progressed to dilated cardiomyopathy (DCM) and heart failure. Skeletal myopathy and WPW were also noted. The teenage sister of the proband is a carrier of the same LAMP2 mutation and has HCM without skeletal myopathy or WPW. The other proband presented with HCM, WPW, and skeletal myopathy as a teenager, whereas his carrier mother developed DCM during her 40s. Skeletal and cardiac muscle sections revealed the absence of LAMP-2 on immunohistochemical staining.

CONCLUSIONS

LAMP2 mutations may account for a significant proportion of cases of HCM in children, especially when skeletal myopathy and/or WPW is present, suggesting that Danon disease is an underrecognized entity in the pediatric cardiology community.

Cardiac tissue-specific repression of CELF activity disrupts alternative splicing and causes cardiomyopathy

Members of the CELF family of RNA binding proteins have been implicated in alternative splicing regulation in developing heart. Transgenic mice that express a nuclear dominant-negative CELF protein specifically in the heart (MHC-CELFDelta) develop cardiac hypertrophy and dilated cardiomyopathy with defects in alternative splicing beginning as early as 3 weeks after birth. MHC-CELFDelta mice exhibit extensive cardiac fibrosis, severe cardiac dysfunction, and premature death. Interestingly, the penetrance of the phenotype is greater in females than in males despite similar levels of dominant-negative expression, suggesting that there is sex-specific modulation of splicing activity. The cardiac defects in MHC-CELFdelta mice are directly attributable to reduced levels of CELF activity, as crossing these mice with mice overexpressing CUG-BP1, a wild-type CELF protein, rescues defects in alternative splicing, the severity and incidence of cardiac hypertrophy, and survival. We conclude that CELF protein activity is required for normal alternative splicing in the heart in vivo and that normal CELF-mediated alternative splicing regulation is in turn required for normal cardiac function.

Pulmonary venous stenosis as an associated manifestation of left-sided obstructive lesions in an infant with partial atrioventricular canal defect

Patients with partial atrioventricular canal defect (PAVC) who present with congestive heart failure within the first year of life are usually found to have associated left-sided obstructive lesions. We present a case of a child with PAVC who subsequently developed progressive pulmonary venous stenosis as a manifestation of her disease.

Bilateral endogenous endophthalmitis secondary to endocarditis with negative transesophageal echocardiogram

PURPOSE

To present a case of bilateral endogenous endophthalmitis as the primary manifestation of an aortic root abscess and endocarditis, both of which were undetected by transesophageal echocardiogram.

DESIGN

Observational case report.

METHODS

A 13-year-old male presented with bilateral endogenous endophthalmitis and previously undiagnosed ventricular septal defect, subaortic stenosis, and a mitral valve cleft.

RESULTS

Cardiac evaluation, systemic evaluation, and transesophageal echocardiogram were negative for endocarditis, but endocarditis and aortic root abscess were discovered at time of cardiac surgery. The patient responded to systemic treatment for endocarditis and surgical management of his cardiac defect.

CONCLUSION

A cardiac source for endogenous endophthalmitis should be considered in the presence of clinical diagnosis of bacteremia, despite a negative transesophageal echocardiogram and systemic evaluation.

A 5-week-old HIV-1–exposed girl with failure to thrive and diffuse nodular pulmonary infiltrates

A 5-week-old female infant with vertical HIV-1 exposure, progressive cough, and failure to thrive was given a diagnosis of bilateral diffuse nodular lung lesions. The child was without fever, leukocytosis, anemia, peripheral adenopathy, or hepatosplenomegaly, and the results of repeated blood tests for HIV-1 DNA were negative. A needle biopsy of the lungs revealed granulomatous inflammation and giant cells, with fungal organisms suggestive of Aspergillus species. A nitroblue tetrazolium dye test performed on the patient's blood specimen demonstrated absence of dye reduction, suggesting a diagnosis of chronic granulomatous disease. Further analysis revealed that the child had a deficiency of the p47(phox) component of the nicotinamide adenine dinucleotide phosphate oxidase system. Thus this child with vertical HIV-1 exposure and diffuse pulmonary nodules actually had an autosomal recessive form of chronic granulomatous disease. This case study clearly demonstrates that children with suspected HIV-1 infection might also need evaluation for primary immunodeficiency and that the clinical immunology laboratory is a powerful adjunct in coming to a correct diagnosis.

Detection of viruses in myocardial tissues by polymerase chain reaction. evidence of adenovirus as a common cause of myocarditis in children and adults

OBJECTIVES

The purpose of this study was to analyze cardiac tissue and blood for viral genomes using polymerase chain reaction (PCR) to define the common viral etiologies of myocarditis by age group.

BACKGROUND

Enteroviruses are considered the most common cause of myocarditis at all ages. Diagnosis relies on viral cultures, serology, and cardiac histology, which lack sensitivity, as well as PCR. However, in many cases enteroviruses are not detected.

METHODS

Cardiac samples were obtained for PCR analysis from patients with myocarditis (n = 624) and dilated cardiomyopathy (DCM) (n = 149). Patients were analyzed by age group, including neonates (n = 116), infants (n = 191), toddlers (n = 87), children (n = 110), adolescents (n = 92), and adults (n = 177). After nucleic acids had been extracted from an endomyocardial biopsy, an explant, or autopsy samples, PCR and reverse transcription PCR were performed to detect the genomic sequences of enterovirus, adenovirus, cytomegalovirus (CMV), herpes simplex virus (HSV), Epstein-Barr virus (EBV), parvovirus, respiratory syncytial virus (RSV), and influenza A virus.

RESULTS

Viral genome was amplified (adenovirus = 142, enterovirus = 85, CMV = 18, parvovirus = 6, influenza A = 5, HSV = 5, EBV = 3, RSV = 1) from 239 (38%) of the 624 samples from myocarditis patients, including 26 patient samples in which dual infection was found. Virus was detected in 30 (20%) of 149 DCM patient samples; only adenovirus (n = 18) and enterovirus (n = 12) were detected.

CONCLUSIONS

Polymerase chain reaction identified adenovirus as the most common virus in the myocardium of children and adults with myocarditis and DCM. Although enteroviruses are also found in these patients, they appear to be a less common cause of myocarditis than adenovirus.

Long-term follow-up of arrhythmias in pediatric orthotopic heart transplant recipients: incidence and correlation with rejection

BACKGROUND

Arrhythmias in adult orthotopic heart transplant (OHT) recipients are common and have been used as predictors of rejection. Because of the paucity of information in pediatric OHT recipients, the purpose of this study was to determine the incidence and correlation of arrhythmias with rejection or with coronary artery disease (CAD) in children.

METHODS

We retrospectively reviewed the records, electrocardiograms (ECGs), and 24-hour ambulatory ECGs of patients who underwent OHT from January 1984 to December 1999. We excluded arrhythmias occurring in the first 2 weeks after OHT.

RESULTS

Sixty-nine patients underwent OHT, received triple-immunosuppression therapy, were discharged home, and have been followed for a mean of 4.7 years (0.3-13 years). Each patient had an average of 10 ECGs and three 24-hour ECGs. Twenty-six patients had 33 arrhythmias: sinus bradycardia (n = 9), atrial tachycardia (n = 9), ventricular tachycardia (n = 3), and Wenckebach periodicity (n = 6). Sinus bradycardia was treated with theophylline in 8 patients, and 2 required pacemakers. Atrial tachycardias (atrial flutter in 4 patients and atrial ectopic tachycardia in 5) were treated with digoxin, propranolol, or procainamide. Ventricular tachycardia was treated with mexiletine, lidocaine, and amiodarone. There were 65 episodes of rejection, 20 of which were moderate/severe (> or =3B). Only Wenckebach was associated with the presence of either rejection or CAD (p < 0.05).

CONCLUSIONS

We noted clinically significant arrhythmias in 38% of the pediatric OHT recipients. Sinus bradycardia, atrial tachyarrhythmias, and ventricular tachycardia occurred with the same frequency. Only new-onset Wenckebach periodicity was noted in the presence of either CAD or rejection. No arrhythmia was of negative predictive value for rejection or CAD. From this data, we suggest that new-onset Wenckebach prompt evaluation for rejection or CAD.

Postmortem cardiomegaly and echocardiographic measurements of left ventricular size and function in children infected with the human immunodeficiency virus. The Prospective P2C2 HIV Multicenter Study

BACKGROUND

Cardiomegaly, seen postmortem in over 50% of HIV-infected children, may occur in the absence of clinical or histopathologic cardiac disease. Premortem echocardiography has also demonstrated clinical and subclinical cardiac disease, including increased left ventricular mass (LVM) and functional abnormalities. No studies have compared these echocardiographic measures of heart size and function with postmortem findings in this population. We sought to determine the postmortem prevalence, clinicopathologic relationships and importance of cardiomegaly in HIV-infected children.

METHODS

We reviewed clinical and postmortem cardiac findings in 30 HIV-infected children who were part of the Prospective P(2)C(2) HIV Study. Postmortem heart weight was compared with clinical measures of heart size and function, with cardiac pathology and with clinical measures reflecting chronic effects of HIV disease.

RESULTS

Postmortem cardiomegaly (heart weight z score >/=2) was identified in 53% of the children. Children with cardiomegaly had increased LVM, increased heart rate, more frequent clinical chronic heart disease and a higher prevalence of postmortem pericardial effusions compared to children without cardiomegaly (P</=.05). The association with LV end-diastolic dimension (LVEDD) did not reach statistical significance (P=.08). No association was found with LV posterior wall thickness (LVPWT), CD4(+) T-cell counts, HIV-1 viral load, hemoglobin, encephalopathy, myocardial histology or myocardial organisms.

CONCLUSIONS

Postmortem cardiomegaly was associated with echocardiographic measures of increased LVM. The pathogenesis appears not to be related to chronic anemia, HIV viral load, the degree of immune suppression or encephalopathy. Autonomic dysregulation, reflected by chronically increased heart rate, may be of pathoetiologic significance.

Aneurysmal dilatation of the ductus arteriosus in a neonate

Fetal ultrasound provides the capacity for early detection of a variety of congenital heart diseases. We report a case of aneurysmal dilatation of a patent ductus arteriosus detected in utero and subsequently confirmed by transthoracic echocardiography in the neonatal period. Prompt recognition of the ductus aneurysm with resultant surgical ligation may have averted potentially serious complications from this condition.

Usefulness of routine surveillance biopsies in children more than one year after orthotopic heart transplantation

This retrospective study examines the usefulness of routine biopsies following the first year after transplant. This study found that routine biopsies detect few episodes of rejection in the first year after transplant and were less useful than nonroutine biopsies.

Subclavian steal syndrome in anomalous connection of the left subclavian artery to the pulmonary artery in d-transposition of the great arteries

Several reports have documented the occurrence of an isolated left subclavian artery in association with both tetralogy of Fallot and double-outlet right ventricle. In certain cases a congenital subclavian or pulmonary artery steal syndrome exists in which the left subclavian artery is connected to the main pulmonary artery via a ductus arteriosus. We describe a subclavian steal syndrome secondary to anomalous origin of the left subclavian artery from the pulmonary artery in d-transposition of the great arteries in a patient with Spondylocostal dysostosis (SCD). Cardiac anomalies are rare in SCD and this constellation of findings have not previously been described.

Sudden death and cardiovascular collapse in children with restrictive cardiomyopathy

BACKGROUND

Restrictive cardiomyopathy (RCM) is rare in children, and the prognosis is poor. In the present study, we evaluated all pediatric patients with RCM who were at our institution during a 31-year period to determine the clinical outcome and cause of death. Those who sustained sudden, unanticipated cardiac arrests were evaluated for risk factors that are predictive of sudden death.

METHODS AND RESULTS

Eighteen consecutive patients were reviewed. Presentation, clinical course, laboratory data, and histopathological evidence of ischemia were compared between patients with and without sudden death events. The results demonstrated that patients who were at risk for sudden death were girls with chest pain, syncope, or both at presentation and without congestive heart failure. Although not statistically significant for sudden death, Holter monitor evidence of ischemia predicted death within months. Histopathological evidence of acute or chronic ischemia was found in the majority of patients, with acute ischemia more common among those who sustained sudden death events.

CONCLUSIONS

All children with RCM are at risk for ischemia-related complications and death, and some are at risk of sudden death. In the present study, patients at risk of sudden death appeared well and had no evidence of ongoing heart failure but often had signs or symptoms of ischemia characterized by chest pain, syncope, or both. ECGs and Holter monitors may be useful screening tools. The use of beta-blockade, the placement of an implantable cardioverter-defibrillator, and preferential status 1A or B listing for cardiac transplantation are proposed for pediatric patients with RCM and evidence of ongoing ischemia.

Premature closure of the foramen ovale associated with aortic stenosis, left ventricular dilation with thrombus, and early mortality

Premature foramen ovale (FO) closure has been postulated as a cause of hypoplastic left heart syndrome. We suggest that premature FO closure is also associated with left ventricular (LV) dilation and LV thrombus formation, and that FO closure in patients with aortic stenosis and LV dilation is a secondary event that occurs later in gestation than that seen with the hypoplastic left heart.

The detection of viral genomes by polymerase chain reaction in the myocardium of pediatric patients with advanced HIV disease

OBJECTIVES

The aim of this study was to investigate the frequency of viral nucleic acid detection in the myocardium of human immunodeficiency virus (HIV)-infected children to determine whether an association exists with the development of heart disease.

BACKGROUND

As improved medical interventions increase the life expectancy of HIV-infected patients, increased incidences of myocarditis and dilated cardiomyopathy (DCM) are becoming more apparent, even in patients without clinical symptoms.

METHODS

Myocardial samples were obtained from the postmortem hearts of 32 HIV-infected children and from 32 age-matched controls consisting of patients with structural congenital heart disease and no myocardial inflammation and no cardiac or systemic viral infection. The hearts were examined histologically and analyzed for the presence of viral sequences by polymerase chain reaction (PCR) or reverse transcription-PCR.

RESULTS

Myocarditis was detected histologically in 11 of the 32 HIV-infected patients, and borderline myocarditis was diagnosed in another 13 cases. Infiltrates were confined to the epicardium in two additional hearts. Virus sequences were detected by PCR in 11 of these 26 cases (42.3%); adenovirus in 6, CMV in 3 and both adenovirus and CMV in 2. Two cases without infiltrates were also positive for adenovirus: one had congestive heart failure (CHF) and the other adenoviral pneumonia. No other viruses were detected by PCR, including HIV proviral DNA. All control samples were negative for all viruses tested.

CONCLUSIONS

These data suggest that the presence of viral nucleic acid in the myocardium is common in HIV-infected children, and may relate to the development of myocarditis, DCM or CHF and may contribute to the rapid progression of HIV disease.

Rett syndrome: analysis of deaths in the British survey

The mortality rate in Rett syndrome is 1.2% per annum, 48% of deaths occurring in debilitated people, 13% from natural causes, 13% with prior severe seizures and 26% sudden and unexpected. Respiratory dysrhythmias were usually present. Neuropathology confirmed reductions in cortical dendrites and in one case immaturity of cardiac conducting tissues.

Association of parvovirus B19 genome in children with myocarditis and cardiac allograft rejection: diagnosis using the polymerase chain reaction

BACKGROUND

Inflammatory diseases of the heart, including myocarditis and cardiac transplant rejection, are important causes of morbidity and mortality in children. Although viral infection may be suspected in either of these clinical conditions, the definitive etiology is often difficult to ascertain. Furthermore, the histology is identical for both disorders. Coxsackievirus has long been considered the most common cause of viral myocarditis; however, we previously demonstrated by polymerase chain reaction (PCR) analysis that many different, and sometimes unexpected, viruses may be responsible for myocarditis and cardiac rejection. In this study, we describe the association of parvovirus genome identified through PCR analysis of cardiac tissue in the clinical setting of myocarditis and cardiac allograft rejection.

METHODS AND RESULTS

Myocardial tissue from endomyocardial biopsy, explant, or autopsy was analyzed for parvovirus B19 using primers designed to amplify a 699-base pair PCR product from the VP1 gene region. Samples tested included those obtained from patients with suspected myocarditis (n=360) or transplant rejection (n=200) or control subjects (n=250). Parvoviral genome was identified through PCR in 9 patients (3 myocarditis; 6 transplant) and no control patients. Of the 3 patients with myocarditis, 1 presented with cardiac arrest leading to death, 1 developed dilated cardiomyopathy, and the other gradually improved. Four of the 6 transplant patients had evidence of significant rejection on the basis of endomyocardial biopsy histology. All transplant patients survived the infection.

CONCLUSIONS

Parvovirus is associated with myocarditis in a small percentage of children and may be a potential contributor to cardiac transplant rejection. PCR may provide a rapid and sensitive method of diagnosis.

Update on pediatric heart transplantation. Long-term complications

Despite evolution to "higher-order" immunosuppressive agents that better control cell-mediated allograft rejection and, therefore, short- and intermediate-term survival, allograft vasculopathy and PTLD remain factors that limit extended graft survival. While improved basic science "bench" techniques have enabled investigation of their pathogenesis at the subcellular and molecular levels, each scientific advance leads the way to the next horizon of complex questions. Only through a more complete understanding of the etiology and pathophysiology of these processes will we be able to design strategies to combat these complications.

Survival after aberrant right subclavian artery-esophageal fistula: case report and literature review

Development of a fistula between an aberrant right subclavian artery and the esophagus is a rare cause of heretofore fatal hematemesis. We report the first known survivor of this devastating complication of the most common aortic arch anomaly. Intraoperative esophagogastroduodenoscopy, intraesophageal balloon tamponade, and arteriography were the keys to successful management. This lesion should be suspected in the setting of bright red, "arterial" hematemesis. Prolonged nasogastric and/or endotracheal intubation should be avoided in patients with a known aberrant right subclavian artery or other aortic arch anomaly.

Fatal myocardial infarction in an 8-year-old girl with systemic lupus erythematosus, Raynaud's phenomenon, and secondary antiphospholipid antibody syndrome

An 8-year-old black girl with a 5 month history of systemic lupus erythematosus (SLE) and secondary antiphospholipid syndrome (APS) developed Raynaud's phenomenon, marked hemolytic anemia, and a fatal myocardial infarction (MI). Pathologic evaluation of the heart demonstrated a transmural acute MI associated with a recent thrombus of the circumflex coronary artery, thrombosis of small intramural arteries, and a coronary arteriopathy resembling fibromuscular dysplasia. Inflammatory or atherosclerotic changes of the coronary arteries were distinctly absent. This case represents the youngest reported patient with SLE, MI, and pathologic confirmation of nonatheromatous coronary artery disease. The observed coronary pathological findings may have accentuated the thrombogenic potential of the APS, resulting in coronary thrombosis. Cardiac lesions in SLE and APS are reviewed, and pathogenetic considerations for the coronary vasculopathy are discussed.