Total anomalous pulmonary venous connection (TAPVC); infradiaphragmatic type

Total anomalous pulmonary venous connection (TAPVC) is a very rare congenital heart disease (CHD), reported in 1-2.6% of all congenital heart disease (1–3). The onset can be abrupt with cardiopulmonary insufficiency or mild, and it has no specific clinical picture. An important step in diagnosis of this entity is to differentiate it from pulmonary disease in a newborn or from persistent fetal circulation with pulmonary hypertension, and, of course, from other CHD. There are three sites of anomalous drainage: supracardiac (50% of the cases), cardiac and infracardiac (25% each). Infracardiac TAPVR is also called infradiaphragmatic. Defects of mixed type are also possible. Evaluation of cardiac structures is very important because in 30% of the cases some associated anomalies may occur.

In many cases of TAPVC, the four pulmonary veins (PV) join together behind the left atrium, where they form a collector. This collector can drain into the right atrium directly, by way of the innominate vein into the superior vena cava (SVC), into the coronary sinus (CS), or through the diaphragm to the venous structures of the abdomen. In the infradiaphragmatic type, the four veins form a descending vertical collector that crosses the diaphragm in front of the esophagus, running parallel to the inferior vena cava (IVC), and drains into the hepatic-portal system (hepatic veins, portal vein or ductus venosus).

The infradiaphragmatic type is associated frequently with pulmonary hypertension due to pulmonary venous obstruction. The presence of an atrial septal defect or patent foramen ovale is extremely important to maintain systemic flow. Pulmonary venous obstruction may occur in any of the forms but is almost always present in the infradiaphragmatic type. Not long ago, administration of prostaglandin E1 in TAPVC was regarded with great reluctance, sometimes even forbidden. Now, there are specific indications. In obstructive forms, the vasodilator effects of prostaglandin E1 may be the benefit or the detriment of the patient. Vasodilating action of prostaglandin E1 includes ducti arteriosus and venosus and systemic or pulmonary vascular muscles.