Effect of multilevel sequential stenosis on lower extremity arterial duplex scanning

Background The sensitivity of lower extremity arterial duplex scanning in detecting a >50% stenosis may be decreased in extremities with multilevel sequential stenosis. Patients and methods The results of lower extremity arterial duplex scanning of the common femoral, upper and lower superficial femoral, above- and below-knee popliteal arteries, and tibioperoneal trunk in 80 extremities of 44 patients were compared to those of arteriography. Thirty-one arterial segments in 27 extremities had a >50% stenosis. The stenoses were categorized as first order (first or only stenotic segment in the extremity, n = 23) and second order (stenosis occurring distal to a >50% stenosis, n = 4, or occlusion, n = 4). Results The sensitivity, specificity, and positive predictive values of duplex scan detection of a >50% arterial stenosis or occlusion were 86%, 96%, and 67% for the common femoral artery; 95%, 98%, and 95% for the upper superficial femoral artery; 97%, 90%, and 88% for the lower superficial femoral artery; 84%, 90%, and 87% for the above-knee popliteal artery; 47%, 98%, and 90% for the belowknee popliteal artery; and 25%, 100%, and 100% for the tibioperoneal trunk. Duplex scanning detected 18 (78%) of the 23 first-order stenoses compared to only 1 (13%) of the 8 second-order stenoses in limbs with multilevel sequential disease (P<0.01). The peak systolic velocity at the stenotic site was significantly higher for first-order (mean ± SD 168 ± 54 cm/s) compared to second-order (38 ± 13 cm/s) stenoses (P<0.00002). Conclusions Duplex scanning was highly sensitive in detecting lower extremity first-order stenoses. Low peak systolic velocities at secondorder stenoses of limbs with multilevel sequential disease significantly decreased the sensitivity of duplex scanning.