Some determinants of papaverine-induced femoral artery pressure gradients

Abstract

The accuracy and reliability of papaverine-induced central arterial to common femoral artery pressure gradients, frequently used to estimate the hemodynamic significance of aortoiliac stenosis, depend on a reproducible, between patient increase in resting common femoral artery blood flow because of the linear relationship between pressure gradient and flow. Blood flow variability and the effect of proximal and distal occlusive disease on femoral artery pressure gradient and flow were determined by three methods: intraoperative electromagnetic blood flow measurements, hemodynamic model analysis, and flow calculations using intraoperative segmental resistance measurements. The ratios of papaverine-induced hyperemic to resting common femoral artery blood flow were 2.80 ± 0.781 (mean ± 1 SD, n = 19) for occluded and 3.07 ± 0.819 ( n = 13, P > 0.5) for open superficial femoral arteries, respectively, when the papaverine-induced central arterial to common femoral artery mean pressure gradient was <10 mm Hg. The flow ratios were 2.70 ± 1.093 ( n = 16) and 2.93 ± 1.027 ( n = 10, P > 0.5) for superficial femoral occlusion and patency, respectively, when the central to femoral mean pressure gradient was ⩾ 10 mm Hg. Hemodynamic model analysis predicts that superficial femoral artery occlusion reduces the hyperemic to resting common femoral artery flow ratio from 2 to 1.8 and from 3 to 2.5. The mean values of segmental resistance measured intraoperatively in 17 additional limbs with and in 17 without superficial femoral occlusion predict a reduction in flow ratios from 2 to 1.75 and from 3 to 2.44 when the superficial femoral is occluded. Model analysis also predicts a mild effect of iliac stenosis on the flow ratios. These results indicate that the increase in common femoral artery blood flow with papaverine is variable (large SD) between patients but only mildly reduced by superficial femoral occlusion and proximal stenosis. Caution in interpretation of the hemodynamic significance of aortoiliac stenosis from mean common femoral artery pressure gradients in the 10 mm Hg range without blood flow measurement is suggested.