Difference Between Double Outlet Right Ventricle and Double Inlet Left Ventricle

Both double outlet right ventricle (DORV) and double inlet left ventricle (DILV) are congenital heart defects that create the phenomenon of a single ventricle. This means that the heart, which normally has two distinct pumping chambers (i.e., right and left ventricles) has only one functional chamber.

DORV and DILV belong to a family of other single ventricle defects, such as hypoplastic left heart syndrome and tricuspid atresia. Moreover, conditions such as pulmonary atresia and particular forms of atrioventricular canal defects may also create the conditions found in a single ventricular heart.

Normally, the right ventricle, which is the lower right chamber of the heart, receives oxygen-poor blood from the right atrium returning from the rest of the body. The right ventricle pumps the blood it receives under low pressure via the pulmonary artery into the lungs. The left ventricle is the corresponding lower left chamber of the heart that receives oxygen-rich blood from the left atrium returning from the lungs. This blood is then pumped by the left ventricle under high pressure to the rest of the body via the aorta.

In DORV, the great arteries (i.e., pulmonary artery and the aorta) both exit from the right ventricle and patients typically have an accompanying ventricular septal defect (VSD). In contrast, patients with DILV have the positions of the great arteries reversed and both of the atria empty into an unusually large left ventricle. Moreover, the right ventricle in DILV is frequently found to be small and there may be both VSDs as well as atrial septal defects (ASDs) present.

DORV and DILV Clinical Presentation

DORV and DILV have a fairly similar clinical picture to what is seen in other congenital heart diseases that tend to develop within the first few weeks of life. Infants may appear bluish (i.e. cyanosis) due to the low levels of blood oxygen saturation. These infants may also show signs of being easily fatigued with difficulties in breathing and gaining weight as well as poor feeding and a general failure in their ability to thrive. Unusual heart sounds referred to as murmurs may be heard on auscultation of the patients.

A key determinant to the spectrum of symptoms that a patient will experience is the degree of pulmonary stenosis that is present. This complication determines how soon a patient will present with symptoms. Patients with severe narrowing of the pulmonary vessel will experience cyanosis due to an insufficient amount of blood being pumped into the lungs. On the other hand, congestive heart failure is seen in patients who have an excessive amount of blood under high pressure being pumped into the lungs.

Management of DORV and DILV

In both cases, surgery is the only option. In DORV, pulmonary artery banding may be done to limit the amount of blood being pumped to the lungs if it is excessive. In cases where blood flow to the lungs is inefficient, a Modified Blalock-Taussig Shunt can be surgically inserted. This shunt creates a passage for blood between the aorta and the pulmonary artery. Infants with a VSD may require open-heart surgery to close the defect. Patients who have more complicated defects may require a Fontan operation, where there the circulatory system and heart is reconfigured to allow for the heart to function with one ventricle. Similar surgical approaches are used in DILV.