The "isolated" popliteal segment: a comparative evaluation of its vascular resistance.

During femoro-popliteal and femoro-distal bypass, measurement of vascular resistance (VR) at the site of graft outflow may be used to quantify "run off". Intra-operative measurements were made in 51 lower limbs to compare VR in different categories of outflow; the "isolated" popliteal segment (IPS group, n = 11), the popliteal artery in continuity with patent vessels to the pedal arch (PIC group, n = 26) and the single calf vessel (SCV group, n = 14). VR was measured both before and after intra-arterial papaverine. The values in the 37 popliteal arteries were correlated with two different methods of arteriographic scoring. Vascular resistance in the IPS group (median 1149 mPRU, P = 0.003) but not significantly different from VR in the SCV group (median 1014 mPRU, range 743-1541 mPRU). VR in the SCV group was significantly greater than that in the PIC group (P = 0.006). After papaverine administration, the same relationships were observed between the IPS, PIC and SCV groups. Both before and after papaverine, VR in the popliteal artery correlated significantly with both arteriographic scores. In terms of VR, the isolated popliteal segment provides an outflow comparable to that of a single calf artery but less favourable than a popliteal artery wtih patent run off.