The vascular steal phenomenon: an experimental model.

A model for the vascular steal phenomenon was designed and evaluated in 10 mongrel dogs in which the aortic bifurcation was used to represent a parent artery with two distal vascular beds. Right lower extremity flow was increased with a femoral arteriovenous fistula, and progressively greater stenoses were applied to the distal abdominal aorta. Significant decreases in left lower extremity flow (a steal) occurred only when the stenosis of the aorta exceeded 60%. There was a direct relationship between the pressure drop across the aortic stenosis and the degree of steal from the left lower extremity. The stenosis required for a steal phenomenon to occur is analogous to a critical arterial stenosis for a given velocity of flow and the specific cross-sectional area of the distal arterial bed.