Characterization of tibial velocities by duplex ultrasound in severe peripheral arterial disease and controls

Background: The relationship between tibiopopliteal velocities and peripheral arterial disease (PAD) severity is not well understood. We sought to characterize tibiopopliteal velocities in severe PAD and non-PAD control patients. Methods: Patients with an arterial duplex ultrasound (DUS) examination with PAD evaluated during a 5-year period were retrospectively compared with non-PAD controls. Control DUS examinations were collected sequentially during a 6-month period, retrospectively. PAD patients included those with lifestyle-limiting intermittent claudication warranting revascularization and patients with critical limb ischemia, defined as ischemic rest pain, gangrene, or a nonhealing ischemic ulcer. For each, tibial and popliteal artery peak systolic velocity (PSV) was measured at the proximal, mid, and distal segment of each artery, and a mean PSV for each artery was calculated. Mean PSV, ankle-brachial indices, peak ankle velocity (PAV), average ankle velocity (AAV), mean tibial velocity (MTV), and ankle-profunda index (API) were compared between the two groups using independent t-tests. PAV is the maximum PSV of the distal peroneal, posterior tibial (PT), or anterior tibial (AT) artery; AAV is the average PSV of the distal peroneal, PT, and AT arteries; MTV is calculated by first averaging the proximal, mid, and distal PSV for each tibial artery and then averaging the three means together; API is the AAV divided by proximal PSV of the profunda. Results: DUS was available in 103 patients with PAD (68 patients with critical limb ischemia and 35 patients with intermittent claudication) and 68 controls. Mean ankle-brachial index in the PAD group was 0.64 +/- 0.25 compared with 1.08 +/- 0.09 in controls (P = .006). Mean PSVs were significantly lower in PAD patients than in controls at the popliteal (64.6 +/- 42.2 vs 76.2 +/- 29.6; P = .037), peroneal (34.3 +/- 26.4 vs 53.8 +/- 23.3; P < .001), AT (43.7 +/- 31.4 vs 65.4 +/- 25.0; P < .001), and PT (43.4 +/- 42.3 vs 74.1 +/- 30.6; P < .001) and higher at the profunda (131.5 +/- 88.0 vs 96.2 +/- 44.8; P = .001). Tibial parameters including PAV (52.6 +/- 45.0 vs 86.9 +/- 35.7; P < .001), AAV (37.4 +/- 26.4 vs 64.5 +/- 21.7; P < .001), MTV (41.7 +/- 30.4 vs 65.4 +/- 21.7; P < .001), and API (0.43 +/- 0.45 vs 0.75 +/- 0.30; P < .001) were significantly lower in the PAD group than in controls. Nonoverlapping 95% confidence interval reference ranges were established for severe PAD and non-PAD controls. Conclusions: This study aims to characterize lower extremity arterial PSVs and ankle parameters in severe PAD and non-PAD controls. These early criteria establish reference ranges to guide vascular laboratory interpretation and clinical decision-making.