Double Outlet Right Ventricle With Transposition

Updated: Apr 29, 2014
  • Author: M Silvana Horenstein, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Overview

Background

Double outlet right ventricle (DORV), as depicted in the image below, is a type of ventriculoarterial connection in which both the aorta (AO) and pulmonary artery (PA) arise entirely or predominantly from the right ventricle (RV). The only outlet from the left ventricle (LV) is a ventricular septal defect (VSD).

Double outlet right ventricle (DORV) with transpos Double outlet right ventricle (DORV) with transposition of the great arteries accounts for 26% of cases of DORV. The aorta (AO) is anterior and to the right of the pulmonary artery (PA), and both arteries arise from the right ventricle (RV). The only outflow from the left ventricle (LV) is a ventricular septal defect (VSD), which diverts blood toward the RV. Pulmonary veins drain into the left atrium (LA) after blood has been oxygenated in the lungs (L). Systemic venous return is to the right atrium (RA).

DORV is usually associated with concordant atrioventricular (AV) connections (ie, the right atrium drains into the RV and the left atrium drains into the LV). Fibrous discontinuity is present between the mitral and semilunar valves, which is referred to as subpulmonic and subaortic conus.

DORV is virtually always associated with a VSD and, occasionally, with an atrial septal defect. Patients with DORV may also present with varying degrees of left ventricular hypoplasia and mitral valve anomalies such as stenosis or atresia. Straddling of the AV valves across the VSD may be present. The aortic valve may be stenosed, and the aortic arch may show coarctation or even interruption. Anomalies of the coronary arteries (CAs), such as those that occur in patients with dextro-transposition of the great arteries may be present. These include the left circumflex arising from the right main, a single right CA, a single left CA, and inverted origin of the CA.

The AV node and His-Purkinje fibers may be displaced in DORV because of the anatomic characteristics of these hearts.

In DORV, the great arteries may take different relationships as follows:

  • In 64% of cases of DORV, the great arteries lie side by side with the AO to the right of the PA and both semilunar valves lying in the same transverse and coronal plane (physiologically similar to tetralogy of Fallot [TOF]).
  • In 26% of cases of DORV, the AO is anterior and to the right of the PA, physiologically resembling transposition of the great arteries (ie, dextro-transposition of the great arteries), with a VSD.
  • In 7% of cases of DORV, the AO is anterior and to the left of the PA (left-transposition of the great arteries).
  • Only 3% of cases of DORV have a normal great artery relationship with the AO arising posterior and to the right of the PA.
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Pathophysiology

The pathophysiology of DORV varies, irrespective of the great arterial relationship (ie, side-by-side, dextro-transposition of the great arteries, left-transposition of the great arteries, normally related). Clinical manifestations may range from that of a large VSD to that of transposition of the great arteries and may mostly depend on the position of the VSD in relation to the great vessels (whether it is subpulmonary or subaortic) and the presence or absence of pulmonary valve stenosis (PS). Both of these factors contribute substantially to the hemodynamics of this congenital heart defect.

In cases of a subaortic VSD, which occurs in 60-70% of patients, the VSD is closer to the aortic valve, thus oxygenated blood from the LV is directed to the AO and desaturated blood from the right atrium (RA) is directed primarily to the PA (see the image below).

Double outlet right ventricle (DORV) with transpos Double outlet right ventricle (DORV) with transposition of the great arteries accounts for 26% of cases of DORV. The aorta (AO) is anterior and to the right of the pulmonary artery (PA), and both arteries arise from the right ventricle (RV). The only outflow from the left ventricle (LV) is a ventricular septal defect (VSD), which diverts blood toward the RV. Pulmonary veins drain into the left atrium (LA) after blood has been oxygenated in the lungs (L). Systemic venous return is to the right atrium (RA).

PS occurs commonly and directs some desaturated blood into the AO. Because of the large VSD, the RV and the LV as well as the AO handle equal systolic pressures. When PS is present, this poses a restriction to flow to the pulmonary circuit, and thus, systolic pressure in the pulmonary arteries is lower. This physiology resembles that of TOF with cyanosis and no congestive heart failure (CHF).

In cases of a subaortic VSD with no PS, systolic pressure in both great vessels as well as in both ventricles is equal; thus, blood follows the path of least resistance (ie, usually towards the lungs) and the clinical picture is that of a large VSD. The degree of blood oxygenation in the systemic as well as the pulmonary circuits is determined by degree of mixing in the systemic (ie, right) ventricle, which, in turn, depends on the degree of resistance upstream of the pulmonary valve.

All patients with elevated pulmonary blood flow (PBF) at systemic or near systemic pressures are at increased risk of developing early pulmonary obstructive vascular disease regardless of their arterial oxygen saturation (ie, presence or absence of cyanosis).

With a subpulmonary VSD (Taussig-Bing anomaly), which occurs in 10% of patients, oxygenated blood from the LV is directed to the PA and desaturated blood from the RA is directed to the AO. This physiology resembles transposition of the great arteries with a VSD; thus, the patient presents with cyanosis and CHF.

In cases of a doubly committed VSD, the left ventricular outflow is not committed preferentially to either semilunar valve. In the presence of PS, the physiology resembles that of TOF, and in the absence of PS, it is that of a large VSD.

In remote VSD, the VSD is far from both semilunar valves. It is most commonly an AV canal-type VSD. Again, the physiology is that of TOF in cases involving PS and is that of a large VSD when flow through the pulmonary valve is not restricted (ie, absence of PS).

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Epidemiology

Frequency

United States

Congenital heart disease (CHD) occurs in less than 1% of all newborns, and DORV is present in 0.5-1.5% of all patients with CHD. The estimated frequency of DORV is 1 case per 10,000 live births. A recent study showed a higher prevalence of DORV, tetralogy of Fallot, and truncus arteriosus, in addition to endocardial cushion defects and single ventricle, in certain regions of the country. [1]

Mortality/Morbidity

Mortality and morbidity depend not only on the overall clinical condition of the patient but also on the type and severity of associated anomalies.

Irrespective of the great vessel relationship, the mortality rate is less than 5% for simple subaortic VSD and is somewhat higher for a doubly committed VSD.

In cases of subpulmonary VSD (Taussig-Bing anomaly), morbidity and mortality depend on whether the patient has already developed pulmonary vascular obstructive disease and also on the type of surgery that is required. [2] In cases of DORV with dextro-transposition of the great arteries, creation of an intraventricular tunnel between the VSD and the AO carries a mortality risk of 10-15%. In subpulmonary VSD with PS (ie, TOF-type physiology), an intraventricular tunnel between the VSD and the AO in addition to relief of PS by a patch graft also carries a mortality risk of 10-15%. In cases of remote VSD, the preferred surgical repair is creation of an interventricular tunnel between the VSD and the AO. However, it carries a mortality rate as high as 30-40%.

When the above surgical procedures cannot be performed (ie, hypoplastic LV, inadequate anatomy for an intracardiac conduit between the LV and the AO, hypoplastic AO, hypoplastic mitral valve), a Fontan-type operation is the choice; the mortality rate has decreased to approximately 5%.

Sex

No sex predilection is reported.

Age

Newborns usually present with this entity; however, in some circumstances (eg, subaortic VSD with mild-to-moderate PS), the diagnosis may not be made until later in infancy.

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