- Duplex Ultrasound: Ankle-brachial index less than or equal to 0.9 (or abnormal ankle PVR waveform at ankle if arteries are incompressible*) with occlusion or focal doubling of peak systolic velocity in the aorta, common iliac artery, or external iliac artery, accompanied by a biphasic or monophasic Doppler wave form at the common femoral artery (loss of early diastolic flow reversal or loss of forward flow during diastole), OR