A medical filler delivery assembly includes a micro catheter 24 for delivering filler material such as filamentary material 20 into an aneurysm 14 in a vessel. The assembly also includes a positioning mechanism which includes a support element 70 made of knitted wires, as well as an expansion mechanism 80, 100 for expanding the support element 70 within the vessel. The support element 70 is able to trap the micro catheter 24 in position such that its distal end 25 is disposed within the aneurysm sac 14. The knitted wire configuration of the support element provides sufficient holding force to the distal end 25 of the micro catheter 24 and also has an open structure which permits continuation of fluid flow through the blood vessel. The entire assembly can be removed from the vessel after the delivery of filamentary material 20, thereby not retaining within the vessel any foreign object such as a stent.
