Anomalous Pulmonary Venous Return

Overview

In total anomalous pulmonary venous return, one or more abnormal connections between the pulmonary veins and the heart causes oxygen-rich blood coming from the lungs to mix with poorly oxygenated blood (blue in color) before being pumped into the body. One result is that the child’s skin color may have a bluish cast (cyanosis).

In the normal heart, well-oxygenated blood returns to the heart from the lungs through four pulmonary veins (two from each lung). The pulmonary veins connect directly into the heart’s left upper chamber (left atrium).

In anomalous pulmonary venous return, the pulmonary veins may connect to other veins, rather than directly to the back of the left upper chamber of the heart (left atrium). These can connect above the level of the heart into other veins (supracardiac), to parts of the heart other than normal (cardiac), or to veins below the level of the diaphragm beneath the lungs (infracardiac), or there may be a combination of these abnormalities (mixed). The most common is a supracardiac connection in which all of the pulmonary veins meet and drain into the major vein that returns blood from the upper body to the heart (superior vena cava). In other cases, the pulmonary veins may meet to form a single vein that drains into the blood circulation of the liver or into the blood vessel that drains blood from the heart muscle (coronary sinus).

When all or most of the pulmonary veins drain in an abnormal fashion, red oxygen-rich blood returning from the lungs mixes with bluish poorly oxygenated blood in the heart’s right upper chamber (right atrium), which results in bluish-colored blood. This blood will flow to the right ventricle, increasing the amount of blood flow to the lungs and could ultimately lead to lung congestion and heart failure.

Symptoms

Bluish discoloration of the skin may be a symptom of this condition. If or when lung congestion and heart failure result, the child may feed poorly and grow inadequately. Severe obstruction of these blood vessels may result in life-threatening deficiency of oxygen (cyanosis) very soon after birth. This is because the heart is unable to get oxygenated blood out of the lungs to the body, requiring emergency surgery or invasive catheterization procedures.

Progression and possible complications

If a baby is born with obstruction in the pathway that lets blood out of the lungs back to the heart, severe cyanosis may develop that’s not responsive to additional oxygen. The cyanosis may be extremely severe, resulting in a life-threatening situation that requires emergency surgical or catheter-based intervention (a minimally invasive procedure performed using thin tubes). If there’s no obstruction of blood in the pathway back to the heart, the effects of the blood flow is like that of a very large hole between the upper chambers of the heart. Lung congestion and heart failure can begin to occur within a few weeks to months after birth. Surgical repair will be necessary in infancy to route the blood directly back to the heart.