Transposition of the great arteries, pulmonary atresia, and multiple ventricular septal defects associated with multiple cardiac rhabdomyomas in a case of tuberous sclerosis

Mitral Ebstein's Anomaly Modified with a Scarred Rhabdomyoma in Tuberous Sclerosis: An Extremely Rare Cause of Mitral Insufficiency

We present an extremely rare case of mitral Ebstein's anomaly that resulted in severe mitral regurgitation (MR). A 41-year-old woman with a history of tuberous sclerosis underwent surgery. Preoperatively, it was assumed that MR had occurred due to leaflet tethering related to left ventricular posterior wall motion asynergy due to a scarred rhabdomyoma. However, surgical inspection revealed a dysplastic posterior leaflet adhering to the ventricular wall, which was completely covered by the endocardium. Both congenital mitral Ebstein's anomaly and acquired wall motion abnormality due to a scarred rhabdomyoma may have contributed to the development of severe MR in this case.

Rhabdomyoma association with atrioventricular septal defect in an infant: a rare coincidence

Cardiac rhabdomyoma is the most common primary heart tumor in childhood. This tumor, which is frequently associated with tuberous sclerosis complex, mostly disappears in childhood with spontaneous regression. Surgical resection is required in case of outflow obstruction and arrhythmia and when protruding to disrupt the filling of the heart cavities. There are very few case series in the literature about rhabdomyoma, whose relationship with other congenital heart defects has not been clearly verified. In this study, we report our approach to the tumor during the corrective surgery of the infant, who was diagnosed with an atrioventricular septal defect and patent ductus arteriosus, and rhabdomyoma accompanying these malformations. We treated this asymptomatic rhabdomyoma with everolimus in line with the current literature, without excision.

Parachute mitral valve: Morphology and surgical management

Background

This review aims to discuss morphology and surgical management of parachute mitral valve.

Methods

A total of 62 articles in the English language with 330 parachute mitral valve patients were retrieved from the PubMed, HighWire Press, and Cochrane Library databases using specific MeSH terms and keywords between January 2000 and December 2018. In these articles, morphology of parachute mitral valve and surgical treatment options were investigated.

Results

A non-syndromic parachute mitral valve was present in 287 patients (87.0%) and a syndromic parachute mitral valve was present in 43 patients (13.0%). A higher number of patients with a non-syndromic parachute mitral valve presented with congestive heart failure compared to syndromic ones. The patients with a non-syndromic parachute mitral valve often had mitral regurgitation, while syndromic parachute mitral valve patients often had mitral stenosis.

Conclusion

Parachute mitral valves are usually not an isolated lesion and are often characterized by a constellation of pathological changes of the mitral valve leaflets, annulus, commissures, subvalvular apparatus, and supravalvular mitral ring. Therefore, the majority of the patients need one or more surgical operations. The incidence of adverse events such as reintervention, postoperative complete heart block, and mortality is high in these patients.

Some Isolated Cardiac Malformations Can Be Related to Laterality Defects

Human beings are characterized by a left–right asymmetric arrangement of their internal organs, and the heart is the first organ to break symmetry in the developing embryo. Aberrations in normal left–right axis determination during embryogenesis lead to a wide spectrum of abnormal internal laterality phenotypes, including situs inversus and heterotaxy. In more than 90% of instances, the latter condition is accompanied by complex and severe cardiovascular malformations. Atrioventricular canal defect and transposition of the great arteries—which are particularly frequent in the setting of heterotaxy—are commonly found in situs solitus with or without genetic syndromes. Here, we review current data on morphogenesis of the heart in human beings and animal models, familial recurrence, and upstream genetic pathways of left–right determination in order to highlight how some isolated congenital heart diseases, very common in heterotaxy, even in the setting of situs solitus, may actually be considered in the pathogenetic field of laterality defects.

Transposition of the great arteries - a phenotype associated with 16p11.2 duplications?

Genetic analyses of patients with transposition of the great arteries have identified rare copy number variations, suggesting that they may be significant to the aetiology of the disease. This paper reports the identification of a 16p11.2 microduplication, a variation that has yet to be reported in association with transposition of the great arteries. The 16p11.2 microduplication is associated with autism spectrum disorder and developmental delay, but with highly variable phenotypic effects. Autism and attention deficit disorders are observed more frequently in children with congenital heart disease than in the general population. Neonatal surgery is proposed as a risk factor, but as yet unidentified genetic abnormalities should also be taken into account. Thus, congenital heart abnormalities may constitute a part of the phenotypic spectrum associated with duplications at 16p11.2. We suggest chromosomal microarray be considered part of the diagnostic work-up in patients with transposition of the great arteries.

Targeted deletion of Tsc1 causes fatal cardiomyocyte hyperplasia independently of afterload

Despite high expression levels, the role of Tsc1 in cardiovascular tissue is ill defined. We launched this study to examine the role of Tsc1 in cardiac physiology and pathology. Mice in which Tsc1 was deleted in cardiac tissue and vascular smooth muscle (Tsc1c/cSM22cre(+/-)), developed progressive cardiomegaly and hypertension and died early. Hearts of Tsc1c/cSM22cre(+/-) mice displayed a progressive increase in cardiomyocyte number, and to a lesser extent, size between the ages of 1 and 6 weeks. In addition, compared to control hearts, proliferation markers (phospho-histone 3 and PCNA) were elevated in Tsc1c/cSM22cre(+/-) cardiomyocytes at 0-4 weeks, suggesting that cardiomyocyte proliferation was the predominant mechanism underlying cardiomegaly in Tsc1c/cSM22cre(+/-) mice. To examine the contribution of Tsc1 deletion in peripheral vascular smooth muscle to the cardiac phenotype, Tsc1c/cSM22cre(+/-) mice were treated with the antihypertensive, hydralazine. Prevention of hypertension had no effect on survival, cardiac size, or cardiomyocyte number in these mice. We furthermore generated mice in which Tsc1 was deleted only in vascular smooth muscle but not in cardiac tissue (Tsc1c/cSMAcre-ER(T2+/-)). The Tsc1c/cSMAcre-ER(T2+/-) mice also developed hypertension. However, their survival was normal and no cardiac abnormalities were observed. Our results suggest that loss of Tsc1 in the heart causes cardiomegaly, which is driven by increased cardiomyocyte proliferation that also appears to confer relative resistance to afterload reduction. These findings support a critical role for the Tsc1 gene as gatekeeper in the protection against uncontrolled cardiac growth.

Transposition of great arteries: new insights into the pathogenesis

Transposition of great arteries (TGA) is one of the most common and severe congenital heart diseases (CHD). It is also one of the most mysterious CHD because it has no precedent in phylogenetic and ontogenetic development, it does not represent an alternative physiological model of blood circulation and its etiology and morphogenesis are still largely unknown. However, recent epidemiologic, experimental, and genetic data suggest new insights into the pathogenesis. TGA is very rarely associated with the most frequent genetic syndromes, such as Turner, Noonan, Williams or Marfan syndromes, and in Down syndrome, it is virtually absent. The only genetic syndrome with a strong relation with TGA is Heterotaxy. In lateralization defects TGA is frequently associated with asplenia syndrome. Moreover, TGA is rather frequent in cases of isolated dextrocardia with situs solitus, showing link with defect of visceral situs. Nowadays, the most reliable method to induce TGA consists in treating pregnant mice with retinoic acid or with retinoic acid inhibitors. Following such treatment not only cases of TGA with d-ventricular loop have been registered, but also some cases of congenitally corrected transposition of great arteries (CCTGA). In another experiment, the embryos of mice treated with retinoic acid in day 6.5 presented Heterotaxy, suggesting a relationship among these morphologically different CHD. In humans, some families, beside TGA cases, present first-degree relatives with CCTGA. This data suggest that monogenic inheritance with a variable phenotypic expression could explain the familial aggregation of TGA and CCTGA. In some of these families we previously found multiple mutations in laterality genes including Nodal and ZIC3, confirming a pathogenetic relation between TGA and Heterotaxy. These overall data suggest to include TGA in the pathogenetic group of laterality defects instead of conotruncal abnormalities due to ectomesenchymal tissue migration.

Prenatal echocardiographic differential diagnosis of fetal cardiac tumors

OBJECTIVES

To present data on echocardiographic findings of fetal cardiac tumors and discuss their differential diagnoses.

METHODS

We retrospectively reviewed 14 cases of fetal echogenic cardiac mass diagnosed between 1990 and 2003; 12 were confirmed to be cardiac tumors and two were false-positive diagnoses. The echocardiographic characteristics examined included number, size, location and associated complications.

RESULTS

Eight fetuses had a single tumor and four fetuses had multiple tumors. The left ventricle was most often affected. Parents of eight fetuses opted for termination of pregnancy, one fetus died in utero and three affected fetuses survived. Histopathological examination revealed cardiac rhabdomyoma in six fetuses, fibroma in two, teratoma in two, lipoma in one and hemangioma in one. The pitfalls associated with prenatal echocardiographic diagnosis of cardiac tumors include: they may be too small to be visualized, intracardiac echogenic foci may mimic tumors, and echogenicity resulting from extracardiac structures or neoplasms near the heart may falsely appear as tumors.

CONCLUSION

Fetal cardiac tumors can be detected by echocardiography. However, differential diagnosis is important as this will affect prognosis and subsequent management.