Echocardiographic and pathoanatomical characteristics of isolated left ventricular non-compaction: a step towards classification as a distinct cardiomyopathy

Familial biventricular myocardial noncompaction associated with Ebstein's malformation

BACKGROUND

Noncompaction of the ventricular myocardium is a rare congenital cardiomyopathy characterized by numerous excessively prominent trabeculations and deep intertrabecular recesses. Noncompaction of the ventricular myocardium is most often an isolated cardiac malformation presenting as a sporadic disease. Associated cardiac anomalies are present in some patients. We report a family with three adult males from consecutive generations having a biventricular form of noncompaction of the myocardium. Two of the patients have an associated Ebstein's malformation of the tricuspid valve.

METHODS

Clinical evaluation and follow-up, electrocardiography, echocardiography, heart catheterization, coronary angiography, contrast cineventriculography, and magnetic resonance imaging.

RESULTS AND CONCLUSIONS

The association of noncompaction of the ventricular myocardium and Ebstein's malformation has not been reported so far. We believe that both defects were caused by a developmental arrest of the right ventricular myocardium. Echocardiography is the diagnostic modality of choice in patients and in the male relatives, irrespective of their clinical status. Thromboembolic events, cardiac rhythm disorders and heart failure mandate treatment. Anticoagulation treatment and implantation of cardioverter-defibrillator pacemaker have to be strongly considered in these patients.

Isolated Left Ventricular Noncompaction of the Myocardium as a Cause of Embolic Superior Mesenteric Artery Occlusion

Isolated noncompaction of the left ventricular (LV) myocardium is a rare congenital disorder resulting from an arrest of the compaction process of the myocardial trabeculae during normal embryogenesis. It is characterized by the presence of prominent LV myocardial trabeculations and deep intertrabecular recesses that are in continuity with the LV cavity. The most common clinical presentation includes progressive LV dysfunction, life-threatening tachyarrhythmias, and the risk for severe cardioembolic events. We describe a case where isolated noncompaction of the LV myocardium was diagnosed after an embolic occlusion of the superior mesenteric artery in a 40-year-old Caucasian woman.

Isolated Ventricular Non-Compaction in Adults With Idiopathic Cardiomyopathy: Cardiac Magnetic Resonance and Pathologic Characterization of the Anomaly

Non-compaction of the ventricular myocardium is an anomaly of myocardial morphogenesis that leads to persistence of the embryonic myocardium with an excessively prominent trabecular meshwork and deep intertrabecular recesses. This report describes 3 cases of isolated left ventricular non-compaction in adults leading to terminal heart failure. We describe their distinctive myocardial histopathology and prospective diagnosis by cardiac magnetic resonance imaging (CMR). Heart transplantation was the only treatment option for all 3 of these severely ill patients. Isolated ventricular non-compaction should be considered in patients with severe idiopathic cardiomyopathy whose symptoms appear in early adulthood, and consideration given for early transplantation. Non-invasive imaging with CMR can confirm the diagnosis.

Usefulness of contrast echocardiography for diagnosis of left ventricular noncompaction

Many imaging modalities have been evaluated for the diagnosis of left ventricular noncompaction (LVNC). Echocardiography with color Doppler flow imaging is currently the diagnostic modality of choice. In this study, the usefulness of contrast echocardiography to diagnose LVNC was examined, and the diagnostic criteria were evaluated.

End-stage Cardiac Failure Caused by Isolated Ventricular Non-compaction: Cardiac Transplantation in a 5-Year-Old Boy

Isolated ventricular non-compaction (IVNC) is a rare congenital cardiomyopathy characterized by arrest in endomyocardial morphogenesis. Presenting features in children include systolic and diastolic ventricular dysfunction, cardiac arrhythmias, and thromboembolism. End-stage cardiac failure necessitating cardiac transplantation is described in adults. We report the unique case of a 5-year-old boy with IVNC and end-stage heart failure who underwent cardiac transplantation. Diagnostic echocardiographic features, gross cardiac morphology, and histopathologic findings are illustrated.

Noncompaction of the left ventricular myocardium diagnosed in pregnant woman and neonate

Noncompaction of the left ventricular myocardium (NCLV) is an uncommon congenital cardiomyopathy with poor prognosis. We describe a case of NCLV that developed in a pregnant woman and her neonate. A nulliparous woman was referred at 24 weeks' gestation due to dyspnea and fetal hydrops. Maternal echocardiography demonstrated NCLV with characteristic findings of prominent and excessive ventricular trabeculations and deep intertrabecular recesses in the left ventricle. An M-mode echocardiography suggested depressed left ventricular systolic function. A fetal echocardiography at 24 weeks' gestation demonstrated cardiomegaly, but morphologic findings were not definitive for NCLV. An emergency cesarean section was performed due to maternal heart failure. A neonatal echocardiography diagnosed NCLV with depressed left ventricular systolic function. The neonate died of cardiac failure on the second day of life. Autopsy confirmed the echocardiographic findings. Since patients with NCLV may develop heart failure, multidisciplinary management is mandatory. In addition, awareness of familial occurrence of NCLV should be kept in mind for early diagnosis in the fetus and neonate.

Heart rate variability in adult patients with isolated left ventricular noncompaction

BACKGROUND

Isolated left venticular noncompaction (IVNC) is a rare congenital heart disease charactrized by a pattern of an excessively prominent trabecular meshwork with deep intertrabecular recesses. Heart rate variability (HRV) has been reported to be impaired in various heart diseases, though little is known regarding HRV in adult patients with IVNC.

METHODS

We measured spectral components of HRV using fast Fourier transformation of 24-h Holter recordings in 10 adult patients with IVNC, 40 patients with myocardial infarction (MI), 40 patients with hypertrophic cardiomyopathy (HCM) and 40 healthy controls.

RESULTS

The low frequency component and the high frequency component of HRV were lower in IVNC patients tahn those in controls (265 +/- 213 ms(2) vs. 469 +/- 195 ms(2), p < 0.01; 80 +/- 51 ms(2) vs. 185 +/- 126 ms(2), p < 0.01). Furthermore, 3 IVNC patients with a previous history of heart failure exhibited more decreased HRV (low frequency, 75 +/- 56 ms(2); high frequency, 39 +/- 18 ms(2)). Contrary, the ratio of low frequency to high frequency component was higher in patients with IVNC than controls (3.5+/-0.5 vs. 3.2 +/- 0.3, p < 0.05). The degree of impaired HRV was severest in MI patients, intermediate in IVNC patients and mildest in HCM patients compared with controls.

CONCLUSIONS

HRV is impaired in adult patients with IVCN, especially in patients with a previous history of heart failure, suggesting vagal withdrawal or sympathetic enhancement. HRV in IVNC adults is less impaired than in MI patients, and more impaired than in HCM patients of our cohort.

Left heart lesions in patients with Ebstein anomaly

OBJECTIVE

To identify the incidence of left heart abnormalities in patients with Ebstein anomaly, recognizing that left-sided lesions in this patient group have been overlooked.

PATIENTS AND METHODS

According to the echocardiography database at the Mayo Clinic in Rochester, Minn, 106 consecutive patients with Ebstein anomaly underwent echocardiography between July 1, 2001, and February 28, 2003. Clinical data as well as electrocardiographic and echocardiographic reports and images were reviewed.

RESULTS

Ebstein anomaly was severe in 76 patients (72%). Previous tricuspid valve surgery was reported in 46 patients (43%), and previous closure of an atrial septal defect or patent foramen ovale was reported in 34 patients (32%). Left ventricular (LV) myocardial changes resembling noncompaction occurred in 19 patients (17.9%), LV systolic dysfunction in 7 patients (7%), LV diastolic dysfunction in 34 (36%) of 95 patients, and LV dilatation in 4 patients (4%). Additional left-sided cardiac lesions included mitral valve prolapse in 16 patients (15%), bicuspid aortic valve in 8 (8%), mitral valve dysplasia in 4 (4%), and ventricular septal defect in 8 (8%). Wolff-Parkinson-White syndrome occurred in 22 patients (21%). The QRS axis tended to be different in LV noncompaction with a mean +/- SD axis of 12 degrees +/- 74 degrees vs 36 degrees +/- 66 degrees overall (P=.08). Otherwise, there were no differences in clinical or surgical data between the groups with normal and abnormal LV myocardium.

CONCLUSIONS

In patients with Ebstein anomaly, left heart abnormalities involving the myocardium or valves were observed in 39% of patients. Ebstein anomaly should not be regarded as a disease confined to the right side of the heart.

Determinants of outcome in isolated ventricular noncompaction in childhood

Isolated ventricular noncompaction is now recognized as an important cause of pediatric cardiomyopathy; however, predictors of outcome have yet to be detailed. Echocardiographic features at presentation, including increased noncompacted to compacted segment ratio and enlarged left ventricular dimension, were found to be associated with poor outcomes (heart transplantation, transplant listing, or death).

[Noncompacted cardiomyopathy of the left ventricule]

In response to a recent review on the role of MRI in the evaluation of cardiomyopathies, we wished, through a clinical example, to focus the attention on noncompacted cardiomyopathy of the left ventricule, an under-diagnosed entity at the border of pediatric and adult imaging, because of its congenital nature but of late presentation.

Natural history and familial characteristics of isolated left ventricular non-compaction

AIMS

Non-compaction of the left ventricle (LVNC) is a disorder of endomyocardial morphogenesis that results in multiple trabeculations in the left ventricular myocardium. The current literature suggests that LVNC in adults is rare and associated with a poor prognosis. Given that the disorder is present at birth and that several studies have reported asymptomatic familial disease in some patients, we hypothesized that there is a long pre-clinical phase of the disease. The aim of this study was to define the prognosis and familial incidence of LVNC.

METHODS AND RESULTS

This study cohort comprised 45 patients (mean age at diagnosis 37 years) consecutively identified at a referral centre for cardiomyopathy over a 10-year period. Twenty-eight patients (62%) had dyspnoea at presentation; 41 (91%) an abnormal ECG; and 30 (66%) left ventricular dilatation and impaired systolic function. Nine patients (20%) had non-sustained ventricular tachycardia on 24 h Holter monitoring. Mean survival from death or transplantation was 97% at 46 months. There were three thromboembolic events in two patients (4%). On systematic family screening, 8 of 32 (25%) asymptomatic relatives had a range of echocardiographic abnormalities, including LVNC, LVNC with impaired systolic function, and left ventricular enlargement without LVNC.

CONCLUSION

This study demonstrates that LVNC is associated with a better prognosis than previously reported. In patients with familial disease, relatives may have features consistent with dilated cardiomyopathy rather than LVNC.

Clinical features of isolated left ventricular noncompaction in children

BACKGROUND

Ventricular noncompaction is a rare unclassified cardiomyopathy due to intrauterin arrest of compaction of the loose interwoven meshwork with limited data regarding diagnosis and outcome in children.

METHODS

In this study we describe clinical features of isolated left ventricular noncompaction (IVNC) in children and compare our findings with those previously reported. A diagnosis of ventricular noncompaction was made according to the characteristic echocardiographic appearance of two-layered myocardial wall consisting of a thin compacted epicardial and a thick noncompacted endocardial layer with numerous, prominent trabeculations and deep intertrabecular recesses communicating with left ventricular cavity.

RESULTS

Nine children, eight male and one female, with ages ranging from 10 days to 12 years and follow-up as long as 5 years were included into the study. The primary diagnosis of IVNC had been missed in four of the patients. Clinical manifestations were heart failure in five patients, cardiac murmur in two, dizziness in one, and palpitation in one patient. All patients, except two asymptomatic ones, had electrocardiographic abnormalities. Four patients required hospital admission for decompansated heart failure. Two patients died during follow-up while waiting for heart transplantation. Familial occurrence, ventricular tachycardia and thromboembolic events were not observed in any of the patients.

CONCLUSIONS

Although IVNC is present at birth, it may become clinically overt at any time from infancy through adolescence. Physicians and echocardiographers should be familiar with the diagnostic pattern of ventricular noncompaction in order to prevent any delay in diagnosis. Since associated morbidity and mortality rates are high, these patients require regular follow-up.

Self and non-self discrimination is needed for the existence rather than deletion of autoimmunity: the role of regulatory T cells in protective autoimmunity

Autoimmune T cells have been viewed for decades as an outcome of immune system malfunction, and specifically as a failure to distinguish between components of self and non-self. The need for discrimination between self and non-self as a way to avoid autoimmunity has been repeatedly debated over the years. Recent studies suggest that autoimmunity, at least in the nervous system, is the body's defense mechanism against deviations from the normal. The ability to harness neuroprotective autoimmunity upon need is evidently allowed by naturally occurring CD4+CD25+ regulatory T cells, which are themselves controlled by brain-derived compounds. These findings challenge widely accepted concepts of the need for discrimination between self and non-self, as they suggest that while such discrimination is indeed required, it is needed not as a way to avoid an anti-self response but to ensure its proper regulation. Whereas a response to non-self can be self-limited by a decreased presence of the relevant antigen, the response to self needs a mechanism for strict control, such as that provided by the naturally occurring regulatory T cells.

Comparison of echocardiographic features of noncompaction of the left ventricle in adults versus idiopathic dilated cardiomyopathy in adults

Noncompaction of left ventricular myocardium (NCLV), or "spongy myocardium," in adults represents an arrest in endomyocardial morphogenesis and occurs as an isolated cardiomyopathy. Because NCLV can be readily mistaken for idiopathic dilated cardiomyopathy, echocardiographic features other than the structural features of the myocardial wall need to be carefully defined for distinguishing the 2 conditions. This study was therefore designed to characterize the echocardiographic features that could be useful for differentiating NCLV from idiopathic dilated cardiomyopathy.

The variable clinical presentation of, and outcome for, noncompaction of the ventricular myocardium in infants and children, an under-diagnosed cardiomyopathy

Noncompaction of the ventricular myocardium is increasingly recognized as an important cause of cardiomyopathy. Its echocardiographic definition, however, is not yet clearly refined, and differentiation from other conditions with hypertrabeculation can be difficult. We report a prospective short-term follow-up of 15 children with noncompaction, excluding those with associated complex congenital cardiac disease. The clinical presentation and outcome were variable, with 2 patients being asymptomatic. For 5 patients, presentation was with cardiac failure due to depressed myocardial function. The function deteriorated in two, remained the same in two, and improved in the other patient. Cardiac failure due to mitral regurgitation was the mode of presentation in 2 patients with preserved myocardial function, one of whom needed replacement of the mitral valve. In 6 patients (40%), symptoms of cardiac failure were due to noncomplex congenital cardiac disease. All of them had ventricular septal defects. In addition, two had cleft mitral valves, and one had a large persistently patent arterial duct. The diagnosis of noncompaction was initially missed on more than one echocardiographic study in one-third of our patients. We conclude that noncompaction is under-diagnosed, and is not as rare as is thought. In children, it is often associated with other cardiac lesions that can cause cardiac failure in the presence of preserved myocardial function.

Familial dilated cardiomyopathy and isolated left ventricular noncompaction associated with lamin A/C gene mutations

LMNA mutations have been associated with familial or sporadic dilated cardiomyopathy (DC), with or without conduction system disease. We studied the LMNA gene in 67 consecutive patients with DC (18 had familial DC, 17 had possible familial DC, and 32 sporadic DC). From genomic DNA, coding regions of the LMNA gene were amplified by polymerase chain reaction, studied by single-strand conformation polymorphism, and cycle sequenced. Mutations were confirmed by restriction fragment length polymorphism. Two disease-causing mutations were found in families A and B. In family A, a novel R349L mutation was present in the mother and her identical twin daughters. They required cardiac transplantation at 36, 18, and 20 years of age. In family B, the R190W mutation was present in 2 cousins with DC and without conduction system disease (1 had cardiac transplantation at 45 years of age and 1 died suddenly at 46 years of age) and in 2 of their sons. The mothers of the 2 affected patients died due to cardiac causes in their 40s (1 died suddenly). One of the carriers fulfilled diagnostic criteria for isolated left ventricular noncompaction. Our data associated the R349L and R190W mutations in LMNA with severe forms of familial DC. LMNA mutations should be considered in the genetic screening of patients with familial DC without conduction system disease. Isolated left ventricular noncompaction may be part of the phenotypic spectrum of the laminopathies.

Novel Gene Locus for Autosomal Dominant Left Ventricular Noncompaction Maps to Chromosome 11p15

BACKGROUND

Left ventricular noncompaction (LVNC) is a congenital unclassified cardiomyopathy with numerous prominent trabeculations and deep intertrabecular recesses in a hypertrophied and hypokinetic myocardium. It has been reported to occur in isolation or in association with congenital heart disease. Mutations in the X-linked G4.5 gene are responsible for cases of isolated LVNC in male infants, but G4.5 mutations were not found in patients with clinical onset of disease in adulthood. In addition, several families with LVNC and an autosomal dominant pattern of inheritance suggest genetic heterogeneity.

METHODS AND RESULTS

We performed a genome-wide linkage analysis in a family with autosomal dominant LVNC and show that a locus containing the LVNC disease gene maps to chromosome 11p15. A peak 2-point logarithm of odds score of 5.06 was obtained with marker D11S902 at theta=0. Haplotype analysis defined a critical interval of 6.4 centimorgan between D11S1794 and D11S928 corresponding to a physical distance of 6.8 megabases. No disease-causing mutation was identified in 2 prime positional candidate genes, muscle LIM protein (MLP) and SOX6.

CONCLUSIONS

We have mapped a locus for autosomal dominant LVNC to a 6.8-megabase region on human chromosome 11p15. Identification of the disease gene will allow genetic screening and provide fundamental insight into the understanding of myocardial morphogenesis.

Isolated left ventricular noncompaction is rarely caused by mutations in G4.5, alpha-dystrobrevin and FK Binding Protein-12

Isolated left ventricular noncompaction (LVNC) is a form of cardiomyopathy that most commonly presents in infancy with a hypertrophic and dilated left ventricle characterized by deep trabeculations and intertrabecular recesses. Our goal was to determine the frequency of mutations in G4.5, alpha-dystrobrevin, and FK Binding protein-12 in isolated LVNC patients. No mutations were identified in 47 of the 48 patients studied, while a splice site acceptor site mutation of intron 10 of G4.5 was identified in one patient, resulting in the deletion of exon 10 from the mRNA.

Noncompacted myocardium in ebstein's anomaly: initial description in three patients

Exercise intolerance in Ebstein's anomaly is usually attributed to desaturation secondary to right-to-left shunting as a result of a small or distorted left ventricle (LV), significant tricuspid valve regurgitation, right ventricular dysfunction, or a combination of these. We observed one boy (age 15 years) and two women (ages 20 and 29 years) with severe Ebstein's anomaly and strikingly abnormal LV myocardium resembling the features described for LV noncompaction. LV size and systolic function were normal in the two women; the boy had a dilated LV with severely diminished ejection fraction. The LV myocardium was found to be unusually coarse and hypertrabeculated, with small intertrabecular recesses and an irregular endocardial surface. The findings in these 3 patients represent the whole spectrum of mild to severe LV noncompaction. Diastolic dysfunction was present in 2 of the 3 patients. Exercise tolerance was diminished in all. There was no mitral or aortic valve disease. The 15-year-old boy underwent heart transplantation 6 months later for biventricular failure. Thus, Ebstein's anomaly does not seem to be a pathology confined to the right ventricle, but may rarely lead to LV noncompacted myocardium. This LV pathology may be an additional explanation for exercise intolerance or signs of left heart failure in patients with Ebstein's anomaly.

Nkx2-5 pathways and congenital heart disease; loss of ventricular myocyte lineage specification leads to progressive cardiomyopathy and complete heart block

Human mutations in Nkx2-5 lead to progressive cardiomyopathy and conduction defects via unknown mechanisms. To define these pathways, we generated mice with a ventricular-restricted knockout of Nkx2-5, which display no structural defects but have progressive complete heart block, and massive trabecular muscle overgrowth found in some patients with Nkx2-5 mutations. At birth, mutant mice display a hypoplastic atrioventricular (AV) node and then develop selective dropout of these conduction cells. Transcriptional profiling uncovered the aberrant expression of a unique panel of atrial and conduction system-restricted target genes, as well as the ectopic, high level BMP-10 expression in the adult ventricular myocardium. Further, BMP-10 is shown to be necessary and sufficient for a major component of the ventricular muscle defects. Accordingly, loss of ventricular muscle cell lineage specification into trabecular and conduction system myocytes is a new mechanistic pathway for progressive cardiomyopathy and conduction defects in congenital heart disease.

Isolated Noncompaction of the Left Ventricular Myocardium in an Elderly Patient

Noncompaction of the ventricular myocardium (NVM) is a rare disorder of endomyocardial morphogenesis characterized by numerous, prominent trabeculations and deep intertrabecular recesses. It is commonly associated with congenital heart disease, but the isolated form (INVM) is not associated with other structural heart diseases. Clinical reports of INVM have been limited to a few case reports and small series of pediatric patients. INVM is considered to be a form of congenital abnormal endomyocardial morphogenesis caused by abnormal cessation of the embryonic development of the ventricular myocardium; most reported cases have been pediatric patients, and autopsy cases of elderly patients have been quite rare. In the present case, an elderly female had INVM associated with severely disturbed left ventricular (LV) function and an enlarged left ventricle similar to dilated cardiomyopathy. The echocardiogram showed prominent trabeculations and deep intertrabecular recesses of the LV walls, especially in the posterior and apical areas. LV contrast echocardiography revealed markedly protruberant trabeculations, which were also observed with computed tomography. Five years later, the patient died of refractory heart failure and ventricular fibrillation. The autopsy revealed numerous excessively prominent trabeculations in the LV myocardium, with deep intertrabecular recesses containing thrombi.

Noncompaction of the ventricular myocardium associated with mitral regurgitation and preserved ventricular systolic function

Noncompaction of the ventricular myocardium is an embryonic cardiomyopathy that is increasingly being recognized. Mitral regurgitation, when present, is usually a result of the associated left ventricular systolic dysfunction. We report 4 patients with noncompaction of the ventricular myocardium in whom ventricular systolic function was preserved. Mitral regurgitation was associated with changes in the mitral valve leaflets and an abnormal coaptation pattern. This association of noncompaction of the ventricular myocardium with mitral regurgitation has not, to our knowledge, been reported.

Adult Case of Isolated Ventricular Noncompaction Discovered by Complete Atrioventricular Block

A 25-year-old male was admitted to hospital with a 3-day history of worsening faintness. The electrocardiogram showed complete atrioventricular block. Echocardiography showed generalized hypokinesis and prominent trabeculations ranged from the apex to the mid-ventricular lateral wall of the left ventricle as well. Furthermore, trabeculations in the left ventricle were seen in his sister and brother. Thus, isolated ventricular noncompaction (IVNC) was diagnosed and a permanent pacemaker was implanted. Common clinical symptoms of IVNC are heart failure, ventricular arrhythmias, and embolic events. This is the first reported adult case of IVNC disclosed by the presence of complete atrioventricular block.

Nucleotide-binding domains of human cystic fibrosis transmembrane conductance regulator: detailed sequence analysis and three-dimensional modeling of the heterodimer

The cystic fibrosis transmembrane conductance regulator (CFTR) protein is encoded by the gene that is defective in cystic fibrosis, the most common lethal inherited disease among the Caucasian population. CFTR belongs to the ABC transporter superfamily, whose members form macromolecular architectures composed of two membrane-spanning domains and two nucleotide-binding domains (NBDs). The experimental structures of NBDs from several ABC transporters have recently been solved, opening new avenues for understanding the structure/function relationships and the consequences of some disease-causing mutations of CFTR. Based on a detailed sequence/structure analysis, we propose here a three-dimensional model of the human CFTR NBD heterodimer. This model, which is in agreement with recent experimental data, highlights the specific features of the CFTR asymmetric active sites located at the interface between the two NBDs. Moreover, additional CFTR-specific features can be identified at the subunit interface, which may play critical roles in active site interdependence and are uncommon in other NBD dimers.

Left ventricular hypertrabeculation/noncompaction

In normal human hearts the left ventricle (LV) has up to 3 prominent trabeculations and is, thus, less trabeculated than the right ventricle. Rarely, more than 3 prominent trabeculations can be found at autopsy and by various imaging techniques in the LV. For this abnormality, different synonyms are used such as spongy myocardium, LV noncompaction, and LV hypertrabeculation (LVHT). In this review it is stated that: (1) LVHT has a higher prevalence than previously thought and the prevalence of LVHT seems to increase with the improvement of cardiac imaging; (2) because LVHT is most frequently diagnosed primarily by echocardiography, echocardiographers should be aware and trained to recognize this abnormality; (3) LVHT is frequently associated with other cardiac and extracardiac, particularly neuromuscular, disorders; (4) there are indications that the cause of LVHT is usually a genetic one and quite heterogeneous; and (5) controversies exist about diagnostic criteria, nomenclature, prognosis, origin, pathogenesis, and the necessity to classify LVHT as a distinct entity and cardiomyopathy by the World Health Organization.

Intractable ventricular tachycardia and bridging to heart transplantation with a non-pulsatile flow assist device in a patient with isolated left-ventricular non-compaction

Intractable ventricular tachycardia was investigated in a 51-year-old man with isolated left ventricular non-compaction during implantation of an automated internal cardioverter-defibrillator. Favorable bridging to cardiac transplantation was achieved with the DeBakey left ventricular assist device (LVAD).

Clinical characterization of left ventricular noncompaction in children: a relatively common form of cardiomyopathy

BACKGROUND

Left ventricular noncompaction (LVNC) is a reportedly uncommon genetic disorder of endocardial morphogenesis with a reportedly high mortality rate. The purpose of this study was to identify the clinical characteristics of children with LVNC.

METHODS AND RESULTS

We retrospectively reviewed 36 children with LVNC evaluated at Texas Children's Hospital (TCH) from January 1997 to December 2002. Five children had associated cardiac lesions. There were 16 girls and 20 boys. The median age at presentation was 90 days (range, 1 day to 17 years). The median duration of follow-up was 3.2 years (range, 0.5 to 12 years). Twenty-seven patients (75%) had ECG abnormalities, most commonly biventricular hypertrophy (10 patients, 28%). Both ventricles were involved in 8 patients (22%) and only the left ventricle in 28 patients (78%). Left ventricular systolic function was depressed in 30 patients (83%), with a median ejection fraction of 30% (range, 15% to 66%) at diagnosis. Nine patients presenting in the first year of life with depressed left ventricular contractility had a transient recovery of function; however, ejection fraction deteriorated later in life, at a median interval of 6.3years (range, 3 to 12 years). Two patients had an "undulating" phenotype from dilated to hypertrophic cardiomyopathy. Two patients (6%) were identified with an underlying G4.5 gene mutation. Five patients (14%) died during the study.

CONCLUSIONS

LVNC does not have an invariably fatal course when diagnosed in the neonatal period. A significant number of patients have transient recovery of function followed by later deterioration, which may account for many patients presenting as adults, some manifesting an "undulating" phenotype.

Developmental anatomy of the heart: a tale of mice and man

Because of the increasing availability of tools for genetic manipulation, the mouse has become the most popular animal model for studying normal and abnormal cardiac development. However, despite the enormous advances in mouse genetics, which have led to the production of numerous mutants with cardiac abnormalities resembling those seen in human congenital heart disease, relatively little comparative work has been published to demonstrate the similarities and differences in the developmental cardiac anatomy in both species. In this review we discuss some aspects of the comparative anatomy, with emphasis on the atrial anatomy, the valvuloseptal complex, and ventricular myocardial development. From the data presented it can be concluded that, apart from the obvious differences in size, the mouse and human heart are anatomically remarkably similar throughout development. The partitioning of the cardiac chambers (septation) follows the same sequence of events, while also the maturation of the cardiac valves and myocardium is quite similar in both species. The major anatomical differences are seen in the venous pole of the heart. We conclude that, taking note of the few anatomical “variations,” the use of the mouse as a model system for the human heart is warranted. Thus the analysis of mouse mutants with impaired septation will provide valuable information on cellular mechanisms involved in valvuloseptal morphogenesis (a process often disrupted in congenital heart disease), while the study of embryonic lethal mouse mutants that present with lack of compaction of ventricular trabeculae will ultimately provide clues on the etiology of this abnormality in humans.

Isolated noncompaction of the left ventricular myocardium in the adult is an autosomal dominant disorder in the majority of patients

Isolated noncompaction of the ventricular myocardium (INVM, MIM 300183 and 604169) is a congenital unclassified cardiomyopathy with numerous prominent trabeculations and deep intertrabecular recesses in a hypertrophied and hypokinetic myocardium. Mutations in the G4.5 gene result in a wide spectrum of severe infantile X-linked cardiomyopathic phenotypes including Barth syndrome with dilated cardiomyopathy and INVM. Molecular genetic analysis of INVM has only been performed in pediatric patients. Although adult INVM patients show similar cardiac abnormalities, the influence of genetic factors, especially of mutations in G4.5, is unknown. We analyzed 25 adult INVM patients for the presence of mutations in the G4.5 gene and performed a pedigree analysis of probands. Mutations were not found in the coding sequence or splice sites of G4.5. Systematic analysis of relatives from seven of nine probands showed multiple affected members consistent with an autosomal dominant pattern of inheritance in the majority of cases. We conclude that INVM in the adult is an autosomal dominant disorder rarely caused by mutations in G4.5 and therefore genetically distinct from infantile X-linked cases.

Isolated non-compaction of the ventricular myocardium: prenatal diagnosis and natural history

Isolated non-compaction of the ventricular myocardium (NCVM) is a rare cardiomyopathy characterized by the persistence of numerous marked ventricular trabeculations and deep intertrabecular recesses with direct vascular supply by the ventricular cavities. We report two cases diagnosed by fetal echocardiography at 27 and 30 weeks' gestation, respectively. Postnatal echocardiography verified the presence of the NCVM seen prenatally. Diagnosis was confirmed at postmortem following neonatal demise in the first case. Surgical intervention for exomphalos and extrahepatic biliary atresia was required in the second case, but there is no clinical abnormality of the cardiovascular system a year after delivery. The uncertainty of prognosis and the familial recurrence described elsewhere indicate the difficulty of counseling and the value of prenatal diagnosis, which is feasible using currently available ultrasonographic equipment.

Expression ofPeg1 (Mest) in the developing mouse heart: Involvement in trabeculation

Peg1 (Mest) is an imprinted gene of unknown function widely expressed in the mouse embryo, predominantly in cells of the mesodermal lineage. We have revealed a restricted expression pattern within the developing heart. Initial uniform expression throughout the linear heart tube subsequently becomes restricted, primarily to the developing myocardial trabeculae of both the atria and ventricles, where it persists into late development. Expression in the atrial appendage myocardium precedes the emergence of trabeculae (pectinate muscles), and occurs earlier and to a greater extent on the right than on the left, reflecting the spatial and temporal pattern of trabeculation. Analysis of myocardial morphology in mice lacking the Peg1 gene, which are viable and appear grossly normal, reveals a subtle alteration in the pattern of trabeculation: an increase in thickness and reduction in density of the compact myocardium, similar to that seen in the human cardiomyopathy ventricular noncompaction.

Isolated ventricular noncompaction is associated with coronary microcirculatory dysfunction

OBJECTIVES

We sought to analyze whether a microcirculatory dysfunction might be associated with isolated ventricular noncompaction (IVNC).

BACKGROUND

In IVNC, which is a cardiomyopathy thus far "unclassified" by the World Health Organization, heart failure and sudden cardiac death are common findings, but the pathophysiologic mechanisms are unknown.

METHODS

In 12 patients with IVNC and 14 control subjects, quantitative evaluation of regional myocardial perfusion (myocardial blood flow [MBF]) and coronary flow reserve (CFR, hyperemic/baseline MBF) was performed using positron emission tomography and (13)N-ammonia. The left ventricular myocardium was divided into nine segments, and the two-dimensional echocardiogram in each patient with IVNC was compared with CFR in each segment. Noncompaction was defined as a two-layered structure with excessive trabeculation.

RESULTS

The CFR in control subjects averaged 4.2+/-0.9, providing a cut-off value > or =2.5, but it was 2.1+/-0.8 in patients with IVNC. A perfusion scan defect was found in 14 of 24 segments with noncompaction, although no defect was found in 76 of 84 normal segments (overall agreement 83%, p < 0.0001 by the chi-square test). In 16 of 21 segments with noncompaction, a decreased CFR was found; but a decreased CFR was also found in 36 of 60 segments without noncompaction (p = NS). In 45 of the 57 segments with wall motion abnormalities, CFR was decreased, but it was preserved in 17 of the 24 segments with normal wall motion (agreement 77%, p < 0.0001).

CONCLUSIONS

In patients with IVNC, a decreased CFR is not confined to noncompacted segments, but extends to most segments with wall motion abnormalities. Thus, coronary microcirculatory dysfunction is associated with IVNC.