An example system can include a tubular braid, a catheter, and an embolic coil. The tubular braid can have an open end, a pinched end, and a predetermined shape. In the predetermined shape, the tubular braid can have two inversions and a middle segment extending between the two inversions that forms a sack. The tubular braid can be implanted in an implanted shape based on the predetermined shape. A distal end of the catheter can be inserted into the sack when the tubular braid is implanted. The embolic coil can be delivered through the catheter into the sack. The opening to the sack can correspond to a constricted columnar segment of the middle segment when the braid is in the predetermined shape.