Normally the emboli originating from the venous thrombus goes to the lung leading to pulmonary embolization. However, in patients with atrial septal defects, a emboli can enter the arterial system through the defect. This may lead to rare complications like stroke and migraine. However, these defects are more common in patent foramen ovale compared to atrial septal defect.

Venous thrombi (clots in the veins) are quite common. Embolization (dislodgement of thrombi) normally go to the lung and cause pulmonary emboli. In an individual with ASD, these emboli can potentially cross through the septum and enter the arterial circulation ^[1][2]. This can cause any phenomenon that is attributed to acute loss of blood to a portion of the body, including cerebrovascular accident (stroke), infarction of the spleen (splenic infarct) or intestines, or even a distal extremity (i.e. finger or toe).

This is known as a paradoxical embolus because the clot material paradoxically enters the arterial system instead of going to the lungs.

Template:WikiDoc Sources Cardiology