Double Outlet Right Ventricle
A rare cono-truncal anomaly in which both the aorta and pulmonary artery originate, either entirely or predominantly, from the morphologic right ventricle.
Double outlet right ventricle (DORV) accounts for about 2-3% of all congenital heart defects, with a birth prevalence rate of 1/ 10,000.
The clinical picture varies widely, depending on the combination of the abnormalities present. Symptoms are generally observed during the first days or weeks of life. Cyanosis is the most frequent sign. Tachypnea or breathlessness, poor feeding and slow weight gain are also common. Tachycardia and/or heart murmur may also be observed. DORV is always associated with a ventricular septal defect (VSD) that allows blood to drain from the left ventricle. DORV is classified into sub-types, based on the relationship of the VSD (subaortic, doubly committed, subpulmonary or non-committed) with the great arteries. Other cardiac anomalies frequently associated with DORV include pulmonary stenosis, various degrees of left and right ventricular hypoplasia, atrioventricular (AV) septal defects, and straddling AV valves. Extracardiac anomalies, such as heterotaxy (polysplenia, asplenia, situs ambiguous) intestinal malrotation and ciliary dysfunction could be associated. It is important to figure out that DORV is not a congenital heart disease per se but a mode of ventriculo-arterial connection. Therefore there are several clinical types of DORV, depending on the presence of a pulmonary stenosis and of associated lesions. The functional classification has identified 5 types of DORV: DORV-VSD type, DORV-Fallot, DORV-Taussig Bing, DORV-non committed VSD, DORV-AVSD-heterotaxy. Each type has a specific clinical presentation and surgical treatment.
DORV results from a failure in the fetal development of the cono-truncus, which is the primary outlet of the heart during embryonic development. The cono-truncal anomalies result in neural crest and second heart field dysfunction. Cardiac progenitor cells are controlled by various genes, such as GDF1 (19p13.11) and CFC1 (2q21.2), which when mutated can result in DORV. DORV is associated with chromosomal anomalies such as 22q11.2 deletion syndrome, trisomy 13, trisomy 18 and CHARGE syndrome and others.
Diagnosis is based on 3D echocardiography showing both great arteries arising from the right ventricle. In complex forms, cardiac catheterization-angiography, magnetic resonance imaging (MRI) and /or computed tomography (CT) scan are required. Recently, 3D printed models have been very useful to plane the surgery.
Differential diagnosis includes transposition of the great arteries, tetralogy of Fallot, ventricular septal defect, and double outlet left ventricle.
DORV can be diagnosed by fetal echocardiography with a good degree of accuracy when the two vessels arise entirely from the right ventricle.
DORV is a sporadic disease. Consanguinity seems to be a risk factor. Genetic counseling is not possible.
Management and treatment
In the presence of two viable ventricles, biventricular repair is the optimal treatment for DORV and it is quite safely achieved in the simple forms (DORV-VSD type, DORV-Fallot type and DORV-TGA type). In the complex forms (DORV with non-committed VSD, DORV-atrioventricular septal defect-pulmonary stenosis-heterotaxy), univentricular repair (Fontan operation) is often preferred by a number of teams, while biventricular repair is performed in selected cases in advanced pediatric heart surgery centers.
Without treatment, prognosis is poor due to severe cyanosis, congestive heart failure or pulmonary hypertension. With biventricular repair, patients have, on average, a normal life expectancy, with possible risk or re-operation. All patients that have received surgery for a DORV require life-long surveillance by a cardiologist. Univentricular palliation requires a very close follow up.