The purpose of this report is to describe the pathophysiology and clinical symptoms of atrial septal defects with emphasis on right ventricular failure and the risk of paradoxical embolism in the setting of a patent foramen ovale. The diagnosis of both the atrial septal defects and the patent foramen ovale, usually is made by echocardiography. Percutaneous transcatheter occlusion of an atrial septal defect and a patent foramen ovale has gained interest for some years as a treatment alternative to surgical closure. Preliminary results of different devices have been encouraging and the method appears to be a viable alternative to surgical closure.