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.
Available from: Claudia Stöllberger
- "Left ventricular hypertrabeculation/noncompaction (LVHT) is a cardiac abnormality of unknown etiology, which is most frequently diagnosed by echocardiography, but can be also visualized by cardiac computed tomography, magnetic resonance imaging or ventriculography . If systematically screened, LVHT is frequently associated with neuromuscular disorders (NMD) . "
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ABSTRACT: Aim of this study was to assess pathomorphologic findings (PATHO) in patients with echocardiographically (ECHO) diagnosed left ventricular hypertrabeculation/noncompaction.
ECHO-criteria for LVHT were: >3 trabeculations, moving synchronously with the compacted myocardium, and forming the noncompacted part of a two-layered myocardium. At autopsy, the hearts were investigated according to the pathologists' preferences.
Twelve patients (2 females, age 27-81years) were included. Seven suffered from neuromuscular disorders, 5 patients were not investigated neurologically. The specimens were acquired after explantation during heart transplantation (n=1), death due to heart failure (n=6), sudden death (n=2), pneumonia (n=2) and stroke (n=1). Eight hearts were investigated without fixation and 4 after formaldehyde fixation. The hearts were opened along the long-axis, in 3 hearts additional short-axis cuts were carried out. At PATHO the trabecular meshwork was better visible in the formaldehyde-fixed hearts than in the fresh hearts. Differentiation from papillary muscles was easier on the long-axis cuts, whereas the two-layered structure was better visible on short-axis cuts. The trabecular pattern was similar in patients with neuromuscular disorders and those who did not undergo neurologic investigation. Subendocardial fibrosis was found in each case. Due to the complex three-dimensional geometry, it was impossible to count the number of trabeculations.
Formaldehyde-fixation should be performed when comparing ECHO with PATHO findings in LVHT. Long-axis as well as short-axis cuts should be carried out in order to assess the course of trabeculations and the extent of the two-layered structure. Subendocardial fibrosis in LVHT deserves further research.
Available from: Yosr Bouhlal
- "At 5 weeks of development in humans, trabeculae are present, and at 5–8 weeks of development, the process of trabecular remodeling and compaction occurs, as the coronary arterial circulation develops . Compaction starts at the base of the heart and continues towards the apex, which may explain why noncompaction most prominently involves the midventricle to apex of the heart [Paterick et al., 2012]. "
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ABSTRACT: 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. © 2013 Wiley Periodicals, Inc.
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