The levoatriocardinal vein is a very rare but clinically important intrathoracic venous anomaly that connects the systemic (cardinal) and pulmonary venous channels. We report 4 adults with pulmonary-systemic venous communications that can explain the morphology of the extracardiac interatrial shunting through the persistent levoatriocardinal vein. We discuss the imaging features of the 2 types of such communications: direct connection of the levoatriocardinal vein (1) with the left atrium and (2) with the left superior pulmonary vein in the absence of obstructive left heart disease. Accurate characterization of these diagnostically challenging cases is important because in addition to hemodynamic imbalance they are at risk of paradoxical embolism. Computed tomography and magnetic resonance imaging are noninvasive imaging techniques that should play increasingly important roles in the evaluation of these anomalies.