Identify the characteristics of a graft at risk.

The presence of a drop in the ankle/arm pressure index of more than 0.15, the presence of a stenosis of more than 70% or a low mean velocity in the graft are potent indicators that the graft is at risk.
A low mean velocity in the graft without an associated stenosis is not associated with graft dysfunction.
False or true aneurysms at the origin or insertion due to anastomosis dehiscence or arteriovenous fistula can also be seen in relation to bypass grafts.