Double outlet right ventricle. Study of 27 cases

Double outlet right ventricle

This review article addresses the history, morphology, anatomy, medical management, and different surgical options for patients with double outlet right ventricle.

[Congenital heart defects of the septa, endocardial cushions and the conotruncus]

During embryological development the heart develops from a simple tube into a complex fully developed heart with four chambers. Hence all congenital heart defects develop before the ninth week of gestation. Currently a steadily increasing number of genetic mutations have been found to be responsible for congenital heart defects. Nevertheless, up to now it has been impossible to diagnose a heart defect just on the basis of molecular pathology. Despite the current excellent prenatal and postnatal ultrasound diagnostics, the post-mortem examination is still the gold standard for the diagnosis of complex heart malformations. However, this requires knowledge of the pathomorphology of the heart malformation in question. Therefore, characteristic and distinguishing features of septal defects including atrioventricular septal defects are presented, especially as the latter are part of complex heart defects, such as conotruncal heart malformations.

Impact of prenatal diagnosis and anatomical subtype on outcome in double outlet right ventricle

BACKGROUND

We sought to investigate the influence of prenatal diagnosis and risk factors for adverse outcomes in double outlet right ventricle (DORV) not associated with heterotaxy.

METHODS

Patients with a pre or postnatal diagnosis of DORV from 2000 to 2007 were identified and classified into 3 subgroups: subaortic ventricular septal defect (VSD) and normal great artery (GA) arrangement (=VSD type), tetralogy of Fallot type, and transposition of the GA type (=TGA type). Patients with heterotaxy, atrioventricular septal defect, valve atresia, and ventricular hypoplasia were excluded. Complex postnatal care was defined as prematurity, need for prostaglandins, surgical repair <2 months, or univentricular palliation. Risk factors for complex postnatal care and demise were sought in multivariable logistic regression models. One hundred fort-five patients were included (93 prenatal, 52 postnatal).

RESULTS

There were 24 pregnancy terminations and 7 in utero deaths. Fetal demise was associated with abnormal karyotype (odds ratio [OR] 1.9, P = .01), any tricuspid valve regurgitation (OR 10.6, P = .01), and hydrops (OR 23.8, P = .02). Of 114 liveborn patients, 23 were tetralogy-type, 67 VSD-type, and 24 TGA-type patients. Postnatal survival of liveborn patients at 1 year was similar in pre- versus postnatally diagnosed patients (84% vs 85%). Abnormal GA relationship (OR 2.9, P = .02), subpulmonary VSD (OR 6.0, P = .001), unobstructed pulmonary blood flow at birth (OR 2.8, P = .05), and aortic coarctation (OR 9.0, P = .007) were associated with suboptimal postsurgical outcomes.

CONCLUSION

Double outlet right ventricle, even without heterotaxy, is associated with complex postnatal care and high risk of early demise. Morphologic subtype, irrespective of pre- or postnatal diagnosis, is a major determinant of outcome.

Role of Endothelin-1/Endothelin-A receptor-mediated signaling pathway in the aortic arch patterning in mice

The intercellular signaling mediated by endothelins and their G protein-coupled receptors has recently been shown to be essential for the normal embryonic development of subsets of neural crest cell derivatives. Endothelin-1 (ET-1) is proteolytically generated from its inactive precursor by endothelin-converting enzyme-1 (ECE-1) and acts on the endothelin-A (ETA) receptor. Genetic disruption of this ET-1/ECE-1/ETA pathway results in defects in branchial arch- derived craniofacial tissues, as well as defects in cardiac outflow and great vessel structures, which are derived from cephalic (cardiac) neural crest. In this study, in situ hybridization of ETA-/- and ECE-1(-)/- embryos with a cardiac neural crest marker, cellular retinoic acid-binding protein-1, shows that the migration of neural crest cells from the neural tube to cardiac outflow tract is not affected in these embryos. Immunostaining of an endothelial marker, platelet endothelial cell adhesion molecule CD-31, shows that the initial formation of the branchial arch arteries is not disturbed in ETA-/- or ECE-1(-)/- embryos. To visualize the subsequent patterning of arch vessels in detail, we generated ETA-/- or ECE-1(-)/- embryos that expressed an SM22alpha-lacZ marker transgene in arterial smooth muscle cells. Wholemount X-gal staining of these mutant embryos reveals that the abnormal regression and persistence of specific arch arteries results in disturbance of asymmetrical remodeling of the arch arteries. These defects include abnormal regression of arch arteries 4 and 6, enlargement of arch artery 3, and abnormal persistence of the bilateral ductus caroticus and right dorsal aorta. These abnormalities eventually lead to various types of great vessel malformations highly similar to those seen in neural crest-ablated chick embryos and human congenital cardiac defects. This study demonstrates that ET-1/ETA-mediated signaling plays an essential role in a complex process of aortic arch patterning by affecting the postmigratory cardiac neural crest cell development.

Morphogenetic considerations on congenital malformations of the outflow tract. Part 2: Complete transposition of the great arteries and double outlet right ventricle

On the basis of our recent embryologic work concerning the separation process of the outflow tract, our study of the morphology of specimens from the Leiden Collection of malformed hearts, and in conjunction with our review of the literature, we have reconsidered the morphogenesis of complete transposition and double outlet right ventricle. In complete transposition, a mirror-image arrangement of the columns of the aorto-pulmonary septum could explain the discordant ventriculo-arterial connexion and might thus play a role in its development. Dedicating a cardinal role to the aorto-pulmonary septum in the morphogenesis of complete transposition does not, however, seem justified. Double outlet right ventricle is not an embryologic entity. From the stance of the embryologist, we prefer to consider double outlet right ventricle in terms of a feature that may occur in specimens related to hearts with either a concordant ventriculo-arterial connexion (such as tetralogy of Fallot, or the so-called Eisenmenger ventricular septal defect), or a discordant ventriculo-arterial connexion (complete transposition).

Anomalous mitral 'cleft' with abnormal ventriculo-arterial connection: anatomical findings and surgical implications

Seven specimens with a 'cleft' mitral valve associated with anomalous chordal fixation and abnormal ventriculo-arterial connection are presented. Four were associated with a discordant ventriculo-arterial connection, two with double-outlet right ventricle, and one with double-outlet left ventricle. In six the chordae from the cleft were attached to the anterior border of a small ventricular septal defect. In the seventh the chordae were attached to an accessory papillary muscle in the left ventricular outflow tract. These clefts differ from those of atrioventricular defects. The cleft is more anterior, there are no septal defects of the atrioventricular canal type, and no deficiency of the basal ventricular septum. Mitral regurgitation or left ventricular outlet obstruction are possible consequences of the anomaly.

Double outlet right ventricle with subvalvular aortic stenosis

A case of double outlet right ventricle had progressive muscular subvalvular aortic stenosis unrelated to the ventricular septal defect. Ventricular systolic pressures were identical and higher than aortic, and the gradient was within the right ventricle. Selective angiocardiography showed a hypertrophied subaortic conus obstructing the right ventricular outlet. Serial haemodynamic and angiographic studies revealed progression of the subaortic stenosis which may have been related to an earlier pulmonary artery banding operation. Distal conal hypertrophy is postulated as the cause of the obstruction.

Double outlet right ventricle: clinical and anatomical spectrum

Thirty-two patients with double outlet right ventricle (DORV) were studied between 1960 and 1976. Associated congenital defects frequently compounded the difficulty of clinical diagnosis. Cardiac catheterisation was performed in 27 patients, and the ventriculograms were studied with particular regard to the relative positions of the great vessels to each other and to the ventricular septal defect. These relationships determine which corrective operation is possible. Correction has been performed in 12 patients with a perioperative mortality of 25%. Although mitral-aortic discontinuity was demonstrated in all cases, consideration of the anatomical spectrum included in the term DORV suggests that discontinuity is not an essential feature. In common with other clinical data and in contrast with necropsy studies, none of our patients was found to show the normal relationship of the great vessels to each other, in which the aorta lies posterior and to the right of the pulmonary artery. The reason for this difference between the clinical and necropsy findings is not apparent. A similar disparity was shown with regard to pulmonary stenosis, which was demonstrated at catheterisation in 68% of the 27 patients (mean gradient 68 +/- 3 mmHg), in contrast with incidences of 18% and 25% in recent necropsy series. Patients in the necropsy studies were frequently neonates or infants, in whom death may have been the result of intractable cardiac failure secondary to excessive pulmonary blood flow. In older patients without pulmonary stenosis and with pulmonary hypertension, frequent observation is imperative so that surgical treatment can be instituted before the development of irreversible pulmonary vascular disease.

Two-dimensional sector scanner echocardiography in cyanotic congenital heart disease

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