Devices for occluding an aperture in tissue or a vessel comprise a first flexible wire and a second flexible wire. Each of the first and second wires is comprised of a shape memory material. Each of the first and second wires is shaped into first and second geometric forms such that the first geometric form of the first wire and the first geometric form of the second wire form a first plate in a first plane, and the second geometric form of the first wire and the second geometric form of the second wire form a second plate in a second plane that is parallel to and remote from the first plane. The first and second plates are separated by a waist formed from two portions of the first wire and two portions of the second wire. Methods for occluding an aperture in tissue or a vessel using such devices are also provided.