Patent Foramen Ovale (a communication between right and left atria), remnant of the fetal circulation, is present in 25% of the general population. In presence of thrombosis in the venous system, thrombus can pass through this little hole in the atrial septum  and reach  the systemic circulation provoking ischemic stroke. With a catheter inserted in the femoral vein we position an umbrella-like device in the left atrium and with a second umbrella in the right atrium we close the hole. More than 500 procedures of closure pfo in patients with cryptogenic (unknown origin) stroke were done in our hospital with no mortality and complication rate of 0,8% We use different kind of device (Amplatzer, Figulla, Primère, Gore) depending on the anatomy of the interatrial septum (presence of aneurism, cribriform septum, lipomatosis of septum primum etc). Due to our policy of adapting the device to specific anatomy ,the rate of residual shunts in our hospital is 2% (in most of the series it varies between 10 and 25%).
Atrial septal defect  is a big hole in the interatrial septum which is closed in similar way as PFO.