Total Anomalous Pulmonary Venous Return, Obstructed

Key Features

Essentials of Diagnosis

• Abnormal pulmonary venous connection leading to cyanosis

• Occurs with or without a murmur and may have accentuated P₂

• Right atrial enlargement and right ventricular hypertrophy (RVH)

General Considerations

• Accounts for 2% of all congenital heart lesions

• Instead of the pulmonary veins draining into the left atrium, the veins empty into a confluence that usually is located behind the left atrium

• However, the confluence is not connected to the left atrium and instead the pulmonary venous blood drains into the systemic venous system

• Therefore, there is complete mixing of the systemic and pulmonary venous blood at the level of the right atrium

• The presentation of a patient with total anomalous pulmonary venous return (TAPVR) depends on the route of drainage into the systemic circulation and whether or not this drainage route is obstructed

• The malformation is classified as either intra-, supra-, or infracardiac

  • Intracardiac TAPVR occurs when the pulmonary venous confluence drains directly into the heart, usually via the coronary sinus into the right atrium (rarely direct drainage into the right atrium)

  • Supracardiac (or supradiaphragmatic) return is defined as a confluence that drains into the right superior vena cava, innominate vein, or persistent left superior vena cava

  • In infracardiac (or infradiaphragmatic) return, the confluence drains below the diaphragm usually into the portal venous system, which empties into the inferior vena cava

    • Infracardiac pulmonary venous return is very frequently obstructed

    • This lesion is a potential surgical emergency

    • Supracardiac veins may also be obstructed, though less commonly

• Rarely, the pulmonary venous confluence drains to more than one location, called mixed TAPVR

• Because the entire venous drainage from the body returns to the right atrium, a right-to-left shunt must be present at the atrial level, either as an atrial septal defect (ASD) or a patent foramen ovale (PFO)

• Occasionally, the atrial septum is restrictive and balloon septostomy is needed at birth to allow filling of the left heart

Clinical Findings

• Severe cyanosis and respiratory distress usually present in infants shortly after birth

• Cardiac examination discloses a striking right ventricular impulse

• S2 is markedly accentuated and single

• Although there is often no murmur, sometimes, a systolic murmur is heard over the pulmonary area with radiation over the lung fields

• Diastolic murmurs are uncommon

• Pulmonary venous return is usually obstructed at the level of the ascending or descending vein that connects the confluence to the systemic veins to which it is draining

• Obstruction can be caused from extravascular structures (such as the diaphragm), or by inherent stenosis within the ascending or descending vein

Diagnosis

Imaging

• Radiography

  • Heart is usually small and pulmonary venous congestion severe with associated air bronchograms

  • In less severe cases, the heart size may be normal or slightly enlarged with mild pulmonary venous congestion

• Echocardiography...