Extracardiac Interatrial Tunnel and Atrial Septal Defect Closed With a Single Atrial Septal Occluder in an Adolescent Girl.

In contrast to the atrial septal defect (ASD) as a congenital interatrial shunt, the extracardiac interatrial tunnel is extremely rare. We report the first percutaneous closure of this entity during closure of a secundum ASD after careful investigation of ischemic risk in a 15-year-old girl. The extracardiac interatrial tunnel could entail interatrial shunt, and, if misidentified as an ASD, could result in lethal procedural complications during surgical or catheter interventions. In our case, the tunnel was also morphologically similar to the cardiac arterial/venous system. Therefore, careful investigation of its potential relationship with coronary circulation was required before its closure.