The Physiologic Basis for the Extra-Anatomic Bypass

Abstract

The effect of different factors on the hemodynamics of extra-anatomic by pass was studied in 12 adult mongrel dogs in an attempt to find a physiologic basis for such bypass operations. It was observed that increased demand of flow following the extra-anatomic bypass graft is met by increasing inflow in the do nor artery proximal to the anastomosis. In the absence of any restriction of in flow, no steal was observed even when the graft flow was increased to 10 times the normal by a fistula on the recipient side. Hypotension per se also failed to produce vascular steal. The graft flow was not affected by changes in the outflow of the donor artery. However, the most significant finding was that once the inflow into the donor artery was restricted down to a critical point, it led to vascular steal. The blood flow measurements 4 weeks after bypass showed an increased flow in all the vessels.