A rare pulmonary-to-systemic venous connection associated with the partially anomalous pulmonary venous connection.

Background: We report an extremely rare case of pulmonary-to-systemic venous connection associated with the partially anomalous pulmonary venous connection. Our case highlights that computed tomography angiography has a significant diagnostic and differential value for this rare anomaly.
Methods and Results: A 32-year-old male presented with chest discomfort for 2 weeks. The electrocardiogram and laboratory were unremarkable abnormalities. Transthoracic echocardiography suggested an enlargement of the right atrium and right ventricle. Cardiac computed tomography angiography images showed partial anomalous drainage of the right superior pulmonary vein into the superior caval vein, and a large pulmonary-to-systemic venous connection from the right middle pulmonary vein into the superior vena cava resulting in left atrial to systemic venous shunt. The patient underwent a successful thoracoscopic correction of partially anomalous pulmonary venous connection. Post-procedural course was uneventful, and he was discharged after 7 days.
Discussion: Pulmonary-to-systemic venous connection may also be called a levoatriocardinal vein. The embryological origin of this venous connection is an abnormal persistency of the splanchnic plexus connecting the pulmonary venous plexus and the cardinal system. The diagnosis of these rare types of the pulmonary to systemic communications has important clinical implications. We report an extremely rare case with pulmonary-to-systemic venous connection from the right middle pulmonary vein into the superior caval vein, although the connection might have been considered a levoatriocardinal vein, there is no separate formation of the right middle pulmonary vein at the time of existence of the splanchnic plexus, so it is inappropriate to explain the collateral channel encountered in our patient on the basis of an embryological remnant, a more appropriate term for these anomalies would be a "pulmonary-to-systemic collateral vein". Because the venous collateral pathway may be a source of the persistent left-to-right shunt and cause clinical manifestations of chronic right heart volume overload later in life. Therefore, we have performed successful thoracoscopic correction of partial anomalous pulmonary venous drainage. The Post-procedural course was uneventful.
Conclusion: The pulmonary-to-systemic venous connection associated with the partially anomalous pulmonary venous connection is a rare congenital malformation. Computed tomography angiography as a noninvasive imaging method plays an important diagnostic and differential value for this entity.
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