Atrial septal defects (ASD) of hemodynamic significance are usually treated surgically in early childhood. However, many cases will not be detected until the patient has become an adult. As there is a risk of development of pulmonary hypertension and tachyarrythmia in hemodynamically significant defects, closure is necessary. Although surgery is considered a safe procedure with very low perioperative mortality, there is a risk of complications and prolonged hospitalization, and postoperative convalescence is two months. Today we are able to offer patients with ASD of the secundum type an alternative treatment using catheter technique. The devices used are self expanding and easy to deploy, with a high success rate and low complication rate. Post-procedural convalescence is two days.