Figure 1.

Darling classification of total anomalous pulmonary venous connection (TAPVC). Type I: supracardiac type. Four pulmonary veins connect to a vertical vein which subsequently drains into the left brachiocephalic vein and superior vena cava (curved arrow). Type II: intracardiac type. The pulmonary veins empty into the coronary sinus or directly into the right atrium. Type III: infracardiac type. The pulmonary veins connect to a vertical vein passes through diaphragm. The pulmonary flow ultimately drains to the systemic venous system, such as portal vein or inferior vena cava (curved arrow). Type IV: mixed type. ASD, atrial septum defect; LV, left antrum; IVC, inferior vena cava; PV, pulmonary vein; RA, right antrum; SVC, superior vena cava.