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

Abstract

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. 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. 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. 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.