How are supracardiac versus infracardiac TAPVR differentiated on imaging?

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Multiple Choice

How are supracardiac versus infracardiac TAPVR differentiated on imaging?

The key idea is where the pulmonary venous confluence drains in relation to the diaphragm. In the supracardiac form, the four pulmonary veins join to a common channel that travels upward and drains into systemic veins above the heart—most often the superior vena cava or innominate veins. On imaging you can trace a vertical vein coursing above the diaphragm into the SVC/innominate region, with the left atrium not receiving direct pulmonary venous return. In the infracardiac form, the drainage is below the diaphragm. The pulmonary venous confluence sends a channel that descends to join the portal venous system, hepatic veins, or the IVC below the diaphragm. Imaging shows this inferior course toward the portal/hepatic venous system rather than to the SVC, and these connections can be more prone to obstruction. So, the distinction rests on the drainage location relative to the diaphragm: above for supracardiac and below for infracardiac. Draining directly into the left atrium or into the coronary sinus is not the characteristic pattern of TAPVR, and saying neither drains to systemic veins contradicts the fundamental abnormal drainage path of TAPVR.

The key idea is where the pulmonary venous confluence drains in relation to the diaphragm. In the supracardiac form, the four pulmonary veins join to a common channel that travels upward and drains into systemic veins above the heart—most often the superior vena cava or innominate veins. On imaging you can trace a vertical vein coursing above the diaphragm into the SVC/innominate region, with the left atrium not receiving direct pulmonary venous return.

In the infracardiac form, the drainage is below the diaphragm. The pulmonary venous confluence sends a channel that descends to join the portal venous system, hepatic veins, or the IVC below the diaphragm. Imaging shows this inferior course toward the portal/hepatic venous system rather than to the SVC, and these connections can be more prone to obstruction.

So, the distinction rests on the drainage location relative to the diaphragm: above for supracardiac and below for infracardiac. Draining directly into the left atrium or into the coronary sinus is not the characteristic pattern of TAPVR, and saying neither drains to systemic veins contradicts the fundamental abnormal drainage path of TAPVR.

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