Competition between collateral vessels in femoro-popliteal by-pass grafting.

In patients with severe ischaemia and maximum collateral development there is no significant competition between the patent superficial femoral artery and common femoral to popliteal by-pass vein graft provided that there is a block in the main line arterial channel between the superficial femoral artery and the popliteal anastomosis of the vein graft.