Noninvasive evaluation of the aorto-iliac segment.

Eighty-five patients (169 limbs) were studied in the Noninvasive Vascular Laboratory at the Lahey Clinic as part of a preoperative evaluation for arterial insufficiency. Segmental Doppler systolic pressures and peak velocity waveform analysis using a directional Doppler were performed on all patients. Normal velocity waveforms demonstrated forward flow during systole, reverse flow during the first half of diastole and a return to forward flow again during the latter part of diastole (triphasic flow). Significantly abnormal waveforms did not demonstrate reverse flow during the first half of diastole (monophasic flow). A significantly abnormal angiogram showed a greater than 50% stenosis in the aorto-iliac segment. A comparison of Doppler velocity waveforms with arteriograms showed a 96% correlation. Most errors in our study were technical; related to the assumption that the inguinal skin crease marked the location of the inguinal ligament and the origin of the common femoral artery. In these instances, the superficial femoral artery not the common femoral artery was sampled. Common sources of false positive studies were severe outflow obstruction or recent surgery to the common femoral artery, both showing a loss of laminar flow and a monophasic waveform. Patients who demonstrate reverse flow in the common femoral artery by directional Doppler examination had adequate inflow to support a femoral-popliteal or femoral-femoral by pass graft. Patients with monophasic flow had either inadequate aorto-iliac segments, recent surgery to the common femoral artery or severe outflow obstruction. Supportive data will be presented in detail.