Left ventricular noncompaction

Monoamniotic monochorionic twins discordant for noncompaction cardiomyopathy

Occasionally "identical twins" are phenotypically different, raising the question of zygosity and the issue of genetic versus environmental influences during development. We recently noted monochorionic-monoamniotic twins, one of which had an isolated cardiac abnormality, noncompaction cardiomyopathy, a condition characterized by cardiac ventricular hypertrabeculation. We examined the prenatal course and subsequent pathologic correlation since ventricular morphogenesis may depend on early muscular contraction and blood flow. The monochorionic-monoamniotic female twin pair was initially identified since one fetus presented with increased nuchal translucency. Complete heart block was later identified in the fetus with nuchal translucency who did not survive after delivery. In contrast, the unaffected twin had normal cardiac studies both prenatally and postnatally. Pathologic analysis of the affected twin demonstrated noncompaction of the left ventricle with dysplasia of the aortic and pulmonary valves. Dissection of the cardiac conduction system disclosed atrioventricular bundle fibrosis. Maternal lupus studies, amniocentesis with karyotype, and studies for 22q11.2 were normal. To test for zygosity, we performed multiple STR marker analysis and found that all markers were shared even using nonblood tissues from the affected twin. These studies demonstrate that monozygotic twins that are monochorionic monoamniotic can be discordant for cardiac noncompaction. The results suggest further investigation into the potential roles of pathologic fibrosis, contractility, and blood flow in cardiac ventricle development.

Ethnic differences in ventricular hypertrabeculation on cardiac MRI in elite football players

PURPOSE

Left ventricular (LV) trabeculation may be more pronounced in ethnic African than in Caucasian (European) athletes, leading to possible incorrect diagnosis of left ventricular non-compaction cardiomyopathy (LVNC). This study investigates ethnic differences in LV hypertrabeculation amongst elite athletes with cardiac magnetic resonance (CMR) and electrocardiography (ECG).

METHODS

38 elite male football (soccer) players (mean age 23.0, range 19-34 years, 28/38 European, 10/38 African) underwent CMR and ECG. Hypertrabeculation was assessed using the ratio of non-compacted to compacted myocardium (NC/C ratio) on long-axis and short-axis segments. ECGs were systematically rated.

RESULTS

No significant differences were seen in ventricular volumes, wall mass or E/A ratio, whereas biventricular ejection fraction (EF) was significantly lower in African athletes (European/African athletes LVEF 55/50 %, p = 0.02; RVEF 51/48 %, p = 0.05). Average NC/C ratio was greater in African athletes but only significantly at mid-ventricular level (European/African athletes: apical 0.91/1.00, p = 0.65; mid-ventricular 0.89/1.45, p < 0.05; basal 0.40/0.46, p = 0.67). ECG readings demonstrated no significant group differences, and no correlation between ECG anomalies and hypertrabeculation.

CONCLUSIONS

A greater degree of LV hypertrabeculation is seen in healthy African athletes, combined with biventricular EF reduction at rest. Recognition of this phenomenon is necessary to avoid misdiagnosis of LVNC.

Mutations in the NOTCH pathway regulator MIB1 cause left ventricular noncompaction cardiomyopathy

Left ventricular noncompaction (LVNC) causes prominent ventricular trabeculations and reduces cardiac systolic function. The clinical presentation of LVNC ranges from asymptomatic to heart failure. We show that germline mutations in human MIB1 (mindbomb homolog 1), which encodes an E3 ubiquitin ligase that promotes endocytosis of the NOTCH ligands DELTA and JAGGED, cause LVNC in autosomal-dominant pedigrees, with affected individuals showing reduced NOTCH1 activity and reduced expression of target genes. Functional studies in cells and zebrafish embryos and in silico modeling indicate that MIB1 functions as a dimer, which is disrupted by the human mutations. Targeted inactivation of Mib1 in mouse myocardium causes LVNC, a phenotype mimicked by inactivation of myocardial Jagged1 or endocardial Notch1. Myocardial Mib1 mutants show reduced ventricular Notch1 activity, expansion of compact myocardium to proliferative, immature trabeculae and abnormal expression of cardiac development and disease genes. These results implicate NOTCH signaling in LVNC and indicate that MIB1 mutations arrest chamber myocardium development, preventing trabecular maturation and compaction.

An adult patient with left ventricular noncompaction detected on radionuclide myocardial perfusion imaging

Left ventricular noncompaction (LVNC) is a rare congenital disease. We herein present less common single photon emission computed tomography (SPECT) images of myocardial perfusion in an adult patient with LVNC. The images revealed segmental and seriously decreased myocardial perfusion with moderate enlargement of the left ventricle. Quantitative electrocardiogram-gated SPECT showed a moderately decreased left ventricular ejection fraction with impaired contractions. The SPECT findings were very similar to those of ischemic cardiomyopathy (ICM). Cardiac magnetic resonance (CMR) and echocardiography confirmed the diagnosis of LVNC. Physicians should be aware of this uncommon cardiomyopathy and conduct comprehensive analyses in order to make a better differential diagnosis.

A case of left ventricular noncompaction accompanying fasciculo-ventricular accessory pathway and atrial flutter

Left ventricular hypertrabeculation/noncompaction (LVHT) is an uncommon type of genetic cardiomyopathy characterized by trabeculations and recesses within the ventricular myocardium. LVHT is associated with diastolic or systolic dysfunction, thromboembolic complications, and arrhythmias, including atrial fibrillation, ventricular arrhythmias, atrioventricular block and Wolff-Parkinson-White syndrome. Herein, we describe a patient who presented with heart failure and wide-complex tachycardia. Echocardiography showed LVHT accompanied with severe mitral regurgitation. The electrophysiologic study revealed a fasciculo-ventricular accessory pathway and atrial flutter (AFL). The AFL was successfully treated with catheter ablation.

Anaesthetic management of a patient with Cushing's syndrome and non-compaction cardiomyopathy for adrenal tumour resection

We describe the anaesthetic management of adrenalectomy in a patient with Cushing's syndrome due to adrenal mass with coexisting non-compaction cardiomyopathy. The problems due to hypersecretion of cortisol in Cushing's syndrome were compounded by the association of a rare form of genetic cardiomyopathy with very few guidelines regarding the perioperative management. The knowledge about the pathophysiological changes, clinical presentation and complications in non-compaction cardiomyopathy is essential for planning the anaesthetic care, and the aim of this presentation is to highlight the issues crucial for management of such challenging patients.

Noncompaction cardiomyopathy in children with congenital heart disease: evaluation using cardiovascular magnetic resonance imaging

Noncompaction of the left ventricle, a genetic cardiomyopathy with a reported incidence of 0.05% to 0.24%, can lead to sudden cardiac death, particularly among children, if left undetected. Because the diagnosis of isolated noncompaction cardiomyopathy (NCM) can be overlooked, its association with other congenital heart diseases (CHDs) makes the diagnosis of NCM even more difficult. This study aimed to assess the impact of NCM on the cardiovascular physiology of children with coexisting CHDs evaluated by cardiovascular magnetic resonance imaging. A case-control study was performed with 12 children (6 patients with combined NCM and CHD and 6 control subjects with isolated CHD). The mean left ventricular end-diastolic and end-systolic volume indices were significantly higher in the CHD patients presenting with NCM than in the CHD patients with no NCM (P = 0.028). However, no differences were observed for right ventricular end-diastolic and end-systolic volume indices, biventricular ejection fractions, stroke volumes and indices, left ventricular wall thickness, left ventricular fractional shortening, cardiac output, or cardiac index. This study suggests that NCM in children with CHDs increases left ventricular volumes, and larger studies are required to demonstrate other changes (e.g., ejection fraction, stroke volume) that were close to being significant.

Left ventricular noncompaction: a 25-year odyssey

Left ventricular noncompaction (LVNC) is a cardiomyopathy associated with sporadic or familial disease, the latter having an autosomal dominant mode of transmission. The clinical features associated with LVNC vary from asymptomatic to symptomatic patients, with the potential for heart failure, supraventricular and ventricular arrhythmias, thromboembolic events, and sudden cardiac death. Echocardiography is the diagnostic modality of choice, revealing the pathognomonic features of a thick, bilayered myocardium; prominent ventricular trabeculations; and deep intertrabecular recesses. Widespread use and advances in the technology of echocardiography and cardiac magnetic resonance imaging are increasing awareness of LVNC, and cardiac magnetic resonance imaging is improving the ability to stage the severity of the disease and potential for adverse clinical consequences. Study of LVNC through research in embryology, imaging, and genetics has allowed enormous strides in the understanding of this heterogeneous disease over the past 25 years.

Frequency of stroke and embolism in left ventricular hypertrabeculation/noncompaction

Left ventricular hypertrabeculation/noncompaction (LVHT/NC) is associated with stroke or embolism (S/E). The aim of this retrospective study was to assess the rate, risk factors, and cause of S/E in patients with LVHT/NC. The medical records of patients with LVHT/NC were retrospectively screened for S/E. For stroke classification, the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria were applied, and for peripheral embolism, angiographic findings were used. Baseline clinical, echocardiographic, and electrocardiographic data were compared between patients with and without S/E. In 22 of 144 patients (15%), stroke (n = 21) or peripheral embolism (n = 1) had occurred. The cause of S/E was cardioembolic (n = 14), atherosclerotic (n = 5), or undetermined (n = 3). S/E occurred before (n = 14) and after (n = 8) the diagnosis of LVHT/NC. Only mean age (60 vs 53 years, p <0.05) and the prevalence of hypertension (32% vs 59%, p <0.05) were higher in patients with S/E than in those without S/E. Among patients with cardioembolic S/E, 13 of 14 had either atrial fibrillation (AF) or systolic dysfunction, and AF as well as systolic dysfunction were found in 4 of 14 patients. In conclusion, S/E in patients with LVHT/NC is not always cardioembolic but may also have an atherosclerotic cause. In the absence of AF or left ventricular systolic dysfunction, cardioembolic S/E is rare in patients with LVHT/NC. These findings suggest that patients with LVHT/NC with systolic dysfunction or AF should receive oral anticoagulation as primary prophylaxis against S/E.

Implantable loop-recorders in myopathic and non-myopathic patients with left ventricular hypertrabeculation/noncompaction

BACKGROUND

Left ventricular noncompaction is associated with arrhythmias. The indication for implantation of devices for primary prophylaxis of sudden cardiac death in noncompaction is controversial, especially for patients without severe systolic dysfunction. The use of implantable loop-recorders to detect arrhythmias has not been reported so far.

METHODS

A retrospective analysis of indications and results of implantation of loop-recorders in patients with left ventricular noncompaction.

RESULTS

Loop-recorders were implanted in 3 patients with noncompaction and moderately or preserved left ventricular systolic function. The recorders revealed pauses N3 s, leading to pacemaker implantation in one patient, and tachycardia leading to radiofrequency ablation in another patient. In the third patient, no arrhythmias have so far been detected.

CONCLUSION

From our limited experience we consider monitoring by a loop-recorder as a useful tool to detect arrhythmias in noncompaction-patients.

Extracellular matrix and heart development

The extracellular matrix (ECM) of the developing heart contains numerous molecules that form a dynamic environment that plays an active and crucial role in the regulation of cellular events. ECM molecules found in the heart include hyaluronan, fibronectin, fibrillin, proteoglycans, and collagens. Tight regulation of the spatiotemporal expression, and the proteolytic processing of ECM components by proteases including members of the ADAMTS family, is essential for normal cardiac development. Perturbation of the expression of genes involved in matrix composition and remodeling can interfere with a myriad of events involved in the formation of the four-chambered heart and result in prenatal lethality or cardiac malformations as seen in humans with congenital heart disease. In this review, we summarize what is known about the specific importance of some of the components of the ECM in relation to the cardiovascular development.