Partial anomalous pulmonary venous return (PAPVR) is a rare entity that is frequently associated with atrial septal defects (ASD), so that when PAPVR is diagnosed, a cardiological study should be performed to rule out ASD (and vice versa).

In this case, the incidental finding of pacemaker malposition led to the realization of a CT scan, where both the atrial defect and the abnormal drainage were evidenced.

Likewise, this patient had signs of pulmonary hyper afflux due to the left-right shunt.

Sinus venosus ASD is a very rare entity (less than 10% of all ASD, according to some series) consisting of a septation defect of the pulmonary veins, vena cava and /or posterior wall of the right atrium. There are two types: upper venous sinus and inferior venous sinus.

The upper sinus venosus ASD is associated with superior anomalous drainage, and the inferior sinus venosus ASD is associated with inferior anomalous drainage.

So, to take home:

• look always at the pacemaker and where electrodes are located
• whenever you see an abnormal pulmonary drainage, look at the heart
• whenever you see an ASD, look for anomalous drains!