Using duplex scanning as an alternative to conventional arteriography in differentiating embolic from thrombotic arterial occlusion in acute limb ischemia

Background: Management of acute limb ischemia is largely based on the etiology of arterial occlusion (embolic vs. thrombotic). Patients with embolic occlusion on atherosclerosed artery usually have the same clinical history and predisposing factors of atherosclerosis. It is usually difficult to differentiate between them using contrast-enhanced magnetic resonance angiography or catheter-based angiography. Purpose: To determine the ability of duplex scanning in differentiating acute embolic occlusion on atherosclerosed artery from thrombotic occlusion. Methods:We prospectively recruited 77 patients (65.3±5.7 years; 65%males) with 87 nontraumatic acute limb ischemia in native arteries. All patients underwent surgical revascularization. Preoperative duplex scan detected arterial occlusion in the following arteries: iliac (6), femoral (34), popliteal (34), infrapopliteal (2), subclavian (4), axillary (1), brachial (4), and forearm arteries (2). We measured the arterial diameters at the site of occlusion (doccl) and at the corresponding contralateral healthy side (dcontra). The difference (Δ) between the two diameters was calculated as (doccl−dcontra). According to surgical findings, limbs were classified into embolic on atherosclerosed artery (E group=limbs) and thrombotic (T group=limbs) groups. Results: Both groups were comparable regarding age, diabetes, hypertension, smoking, atrial fibrillation, and time of presentation. Δ in the E group was 0.85±0.82 mm vs. −0.13±1.02 mm in the T group (Pb.001). A value of ≥0.5 mm forΔ had 82% sensitivity and 79% specificity for the diagnosis of embolic occlusion on atherosclerosed artery (CI 0.72–0.90, Pb.001), whereas a value of ≤−0.5 mm for Δ had 82% sensitivity and 79% specificity for thrombotic occlusion (CI 0.72–0.90, Pb.001). Conclusion: Duplex scanning can accurately and easily differentiate acute embolic occlusion on atherosclerosed artery from thrombotic occlusion, where≥0.5 mm dilatation or diminution in the occluded artery diameter is a useful duplex sign for diagnosing embolic occlusion on atherosclerosed artery or thrombotic occlusion, respectively.