We present the case of a patient who underwent a percutaneous secundum atrial septal defect (ASD II) closure with an undersized septal occluder device. One week and one month later she experienced two transient ischemic attacks. Three-dimensional transesophageal echocardiography (TEE) revealed a residual patent foramen ovale (PFO) with a positive Valsalva bubble test. She underwent a second procedure under the 3D TEE guidance and the PFO was successfully closed percutaneously using a PFO occluder device that was attached to the ASD device. Accurate ASD and PFO morphology assessment and appropriate device selection are the key factors in the success of percutaneous closure. 3D TEE is an innovative diagnostic technique, providing a complete description of the cardiac defect and improving spatial orientation. Real-time 3D TEE is the appropriate guidance for successful and accurate positioning of the device.