Abstract: A closure device for sealing an atrial septal defect is provided. The closure device includes a distal closure portion and a proximal closure portion. The distal closure portion includes a distal membrane covering a plurality of distal fingers that extend in a distal plane. The proximal closure portion includes a proximal membrane covering a plurality of proximal fingers that extend in a proximal plane. The closure device also includes a waist section extending axially between the plurality of distal fingers and the plurality of proximal fingers. The distal closure portion is configured to sealingly engage one of the left or right side of a septal wall, the proximal closure portion is configured to sealingly engage the other of the left or right side of the septal wall, and the waist section is configured to be positioned and centered in an atrial septal defect between the left and the right septal wall.