Total anomalous pulmonary venous connection

The pulmonary veins usually connect to the left atrium. However, in total anomalous pulmonary venous connection (TAPVC), there is no direct connection between any pulmonary vein and the left atrium. The pulmonary veins that normally bring oxygen-rich blood back from the lung are not connected to the left atrium. Instead, they drain through abnormal connections to the right atrium.

In the right atrium, the oxygen-rich blood from the pulmonary veins mixes with the oxygen-poor venous blood from the body. Some of this mixture then passes through an atrial septal defect or a PFO into the left atrium. The result is that the blood flowing to the body is poorly oxygenated. The rest of the poorly oxygenated mixture flows through the right ventricle into the pulmonary artery and on to the lungs.

Both congestive heart failure and pulmonary artery hypertension may develop. Signs of these may appear soon after birth and vary in severity. They include a lethargic appearance, pallor or cyanosis, poor feeding and weight loss. TAPVC is usually repaired in early infancy or when the abnormality is diagnosed. Surgical repair involves reconnecting the pulmonary veins to the left atrium and closing the atrial septal defect or PFO.

Diagram 2.15 Total anomalous pulmonary venous connection (showing pulmonary veins connected to the left innominate vein) 1 - superior vena cava 2 - atrial septal defect 3 - left innominate vein 4 - pulmonary veins Oxygenated blood returning from the lungs is routed back into the superior vena cava, rather than the left atrium. The presence of an atrial septal defect is necessary to allow partially oxygenated blood to reach the left side of the heart.