Utility of Duplex Scanning for Peripheral Arterial Disease in 2006
Flow velocities are well known in normal peripheral arteries. Normal velocities are presented in the
Table. Associated waveforms are triphasic.
Artery Peak Systolic Velocity (cm/s)
External Iliac 119.3 ± 21.7
Common Femoral 114.1 ± 24.9
Superior Femoral 90.8 ± 13.6
Popliteal 68.8 ± 13.5
Abnormal velocities and waveforms describing arterial stenosis have also been described: 1%-19% stenosis: normal waveforms and velocities with minor spectral broadening on the down slope of the sys-tolic portion of the waveform. 20%-49% stenosis: marked spectral broadening is combined with at least a 30% increase in peak systolic velocity but the end-systolic reverse flow component of the waveform is preserved. 50%-99% stenosis: extensive spectral broadening is combined with at least a 100% increase In peak systolic velocity and the reverse flow component is lost. Occluded: no flow is detected in an adequately visualized arterial segment. A peak systolic velocity > 200 cm/s in a lower extremity artery is indicative of a = 50% angiographic stenosis. These observations have been extended to tibial arteries. Tibial artery flow velocities have been quantitated in normals and in patients with occlusive disease involving either the aortoiliac segments, femoropopliteal arteries or both supra and infrainguinal arteries. The data indicate (1) proximal occlusive disease reduces peak velocities in tibial arteries, (2) there are no significant differences in peak systolic velocities of the three crural vessels, and (3) there is little drop in peak systolic velocity going from proximal to distal in a continuously patent tibial artery.
In arteries proximal to the tibials, sensitivities, specificities, PPVs, and NPVs for color flow duplex scanning in comparison to angiography in detecting a > 50% stenosis or occlusion generally exceed 85%. There are no substantial differences in the accuracy of duplex scanning in limbs with differing patterns of atherosclerosis In arterial segments that are either occluded or contain a > 50% stenosis duplex scanning can distinguish angiographic stenosis from occlusion in 98% of cases. Compared to angiographic controls, duplex scanning predicts interruption of contin-uous patency of the anterior and posterior tibial arteries with sensitivities and specificities exceeding 90%.
Based on such data many centers are now utilizing lower extremity arterial duplex scanning routinely in the care of patients with lower extremity arterial disease. The accuracy of the technique is clearly gaining acceptance. Recent studies report excellent results using duplex scanning of ilio-femoral-popliteal arteries to localize stenoses in the selection of patients for transluminal angioplasty without antecedent angi-ography and in the selection of patients for lower extremity arterial bypass, including selection of distal anastomotic sites. The technique is accurate in determining if a patient is suitable for a percutaneous intervention and can aid in helping a patient decide if he or she wishes intervention for intermittent claudication. Peripheral duplex scanning is also the preferred method for follow-up of lower extremity vein grafts and angioplasty sites in the lower extremity arteries. The ease of access and accuracy of arterial duplex scanning make it the preferred imaging modality for many patients with peripheral arterial disease.