Influence of knee flexion on femorodistal bypass hemodynamics.

The influence of knee flexion on the hemodynamics of ten Below Knee (B.K.) femoro-popliteal by-passes (mean follow-up 45 mos. min. 2-max. 134) has been studied by means of Doppler Pressure Index (P.I.) and Pulse Volume Recorder (P.V.R.). In all patients operative indication was limb salvage and the graft material was autologous saphenous vein (ASV) in 5 cases, PTFE in 3 and Dacron in 2. Calf and ankle P.I. and P.V.R. wave amplitude modifications have been evaluated bilaterally just after the beginning of knee flexion (80 degrees) and at 10 and 15 minute intervals. The knee flexion influenced detrimentally (p less than 0.025) the P.I. (calf: -10.9% at the beginning, -17.8% at 10 min. and -20.5% at 15 min.; ankle: -7.4% at the beginning, -13.6% at 10 min. and -16.5% at 15 min.). P.I. was minimally affected by knee flexion in non-grafted limbs (-3%). No consistent P.V.R. modifications were observed.