Normally, the aorta (i.e., the main artery transporting blood from our heart to the rest of our body) originates from the left ventricle, while the pulmonary artery, which carries blood from the heart to the lungs, originates from the right ventricle. These two vessels are commonly referred to as the ‘great arteries’ and in the rare congenital disorder known as double outlet right ventricle (DORV) both of these arteries exit from the right ventricle.
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Infants born with the condition usually tend to have a defect in the ventricular septum, which is the muscular wall in the heart separating the right and left ventricles. While pathological, the ventricular septal defect (VSD) is actually needed in DORV, because it enables, in some instances, the passage of oxygen-rich blood from the left ventricle to the aorta and the rest of the body. However, the level of oxygen is reduced and it is not sufficient for physiological needs, because it mixes with oxygen-poor blood in the right ventricle.
In addition to VSD, accompanying defects that may be seen in children with DORV include pulmonary valve stenosis and transposition of the great arteries. These are a blockage or narrowing of the pulmonary artery and reversal of the normal origin of the great arteries, respectively.
In the late 1950s, the term DORV was first coined by Witham. However, the condition was well known before this time, dating back to 1875. DORV is one abnormality in a spectrum of anomalies pertaining to cardiac structure and function. These anomalies range from tetralogy of Fallot (i.e., a congenital defect classically involving four anatomical cardiac abnormalities) to complete transposition of the great arteries (i.e., the pulmonary artery and the aorta switch places).
The clinical presentation of DORV varies. On one end of the spectrum, the infant may present with profound cyanosis, while on the other end may have fulminant congestive heart failure.
Types of DORV
Based on the location of the VSD, four common types of DORV may occur. When the VSD presents just below the aorta, the condition is referred to as a DORV with subaortic VSD (DORV-SA-VSD). DORV-SA-VSD allows blood to flow from the left ventricle, through the defect in the septum to the aorta, while blood from the right ventricle will flow mostly into the pulmonary artery.
A VSD that is located just below the pulmonary artery is referred to as a DORV with a subpulmonary VSD (DORV-SP-VSD). DORV-SP-VSD is also known as Taussig-Big anomaly. In this type of DORV, oxygen-rich blood from the left ventricle flows through the VSD and mainly into the pulmonary artery, while oxygen-poor blood from the right ventricle flows mostly into the aorta.
The other two types of DORVs are DORV with a doubly committed VSD (DORV-DC-VSD) and DORV with a non-committed VSD (DORV-NC-VSD). In DORV-DC-VSD, there are two VSDs. One VSD presents below the aorta and the other below the pulmonary artery. The VSD is not located near the pulmonary artery of the aorta in DORV-NC-VSD.