Femoral artery‐vein shunt steals collateral flow and promotes collateral arteriogenesis

Abstract

To study high flow‐stimulated collateral artery enlargement, a side to side femoral artery‐vein anastomosis was established in Yucatan pigs (~40 kg, n=7, limited to cage activity). The femoral artery was occluded proximally to the a‐v shunt by an Ameroid occluder placed between the a‐v shunt and a proximal transonic flow probe. Femoral artery blood flows (BF) were monitored daily to evaluate the magnitude and time‐course of BF change. Before femoral artery occlusion, BF through the proximal flow probe increased from ~400 to 700 ml/min, while BF through the distal flow probe (distal to the shunt) were ~100 to 200 ml/min. Following femoral artery occlusion (~ 2 wks post surgery), proximal BF reduced to only ~50 ml/min, while distal BF (i.e., arising from collateral dependent BF delivered distal to the shunt) gradually increased from ~200 to 400 ml/min by 4 wks post‐surgery. Thus, a significant­ly greater collateral‐depen­dent BF was shunted back to the central circulation over time. This placed increasing flow demands on the collateral circuit. Angiograms showed extensive collateral vessel development in the upper thigh area in the leg with the a‐v shunt, primarily arising from the profunda artery. We attribute this collateral vessel enlarge­ment to the apparent high shear stress induced in these vessels that would occur to support flow through the low‐resistance shunt created by the by‐pass. Thus, we conclude that an exceptional enlargement of the collateral circuit can be induced over a rather brief period of time, if the stimulus for collateral development is sufficient.Supported by NIH grant P01HL 52490‐12