of the amplatzer trade mark septal occluder produced by aga medical corp the device 140 is collapsed by pulling the exterior faces of the flanges 14 away from one another which causes the device 140 to lengthen and simultaneously reduce in diameter when the separating force is removed the flanges 14 return to the expanded configuration more particularly as shown in fig2 a and 21 b the device 140 is initially collapsed within a catheter 142 of about 5 mm in diameter which is able to pass through an opening in the septum as shown in fig2 a to 22 c the device 140 is then partially deployed from the catheter 142 by movement of wire 144 and thus head 146 relative to the catheter 142 this results in part of the device 140 expanding to form the first flange 14 as shown in fig2 a and 23 b fall deployment of the device 140 by further relative movement of the wire 144 and the head 146 relative to the catheter 142 results in the remainder of the device 140 expanding to form the second flange 14 the device 140 is initially attached to the head 146 by three pins 148 which are remotely released after the device has been deployed from the catheter 142 in other similar embodiments not shown the catheter 142 has a diameter of 4 6 mm and the device 140 is initially attached to the head 146 by one or two releasable pins 148 fig2 shows a twelfth embodiment of a device 150 for treating heart failure in this embodiment a tube 152 of about 8 mm internal diameter provides an external fluid communication path between the heart 39 s left and right atriums 154 and 156.